阅读说明：本技术 缸压传感器的故障诊断装置 (Fault diagnosis device for cylinder pressure sensor ) 是由 藤原颂示 桥本英俊 奥村拓仁 中川滋 鸟居和 木下真幸 津村雄一郎 田中大介 每熊泰 于 2019-07-22 设计创作，主要内容包括：本发明的目的在于,提高缸压传感器故障诊断的正确度。本发明中的缸压传感器的故障诊断装置(100)具备缸压传感器(SW6)和诊断部(111)。诊断部(111)具有：读取部(1113),读取相对于压缩上止点而言滞后特定曲轴转角的最高点后时间点处的缸压传感器的信号和相对于压缩上止点而言提前特定曲轴转角的最高点前时间点处的缸压传感器的信号；故障判定部(1112),当最高点后时间点处的缸压传感器的信号值和最高点前时间点处的缸压传感器的信号值的差额的大小超过预先设定的阈值时,判定为缸压传感器故障。(The purpose of the present invention is to improve the accuracy of cylinder pressure sensor failure diagnosis. A failure diagnosis device (100) for a cylinder pressure sensor is provided with a cylinder pressure sensor (SW 6) and a diagnosis unit (111). The diagnosis unit (111) has: a reading unit (1113) that reads a signal of the cylinder pressure sensor at a time point after the peak of the specific crank angle with respect to the compression top dead center and a signal of the cylinder pressure sensor at a time point before the peak of the specific crank angle with respect to the compression top dead center; and a failure determination unit (1112) that determines that the cylinder pressure sensor has failed when the magnitude of the difference between the signal value of the cylinder pressure sensor at the time point after the maximum point and the signal value of the cylinder pressure sensor at the time point before the maximum point exceeds a preset threshold value.)

1. A failure diagnosis device of a cylinder pressure sensor, comprising:

a cylinder pressure sensor that is provided in a combustion chamber facing an engine mounted on an automobile and outputs a signal corresponding to a pressure in the combustion chamber;

a diagnosis unit that receives a signal input from the cylinder pressure sensor and diagnoses a failure of the cylinder pressure sensor based on the signal from the cylinder pressure sensor;

wherein the diagnosis section includes:

a reading unit that reads a signal of the cylinder pressure sensor at a 1 st time point that lags behind a specific crank angle with respect to a compression top dead center and a signal of the cylinder pressure sensor at a 2 nd time point that advances the specific crank angle with respect to the compression top dead center;

and a determination unit configured to determine that the cylinder pressure sensor is defective when a magnitude of a difference between the signal value of the cylinder pressure sensor at the 1 st time point and the signal value of the cylinder pressure sensor at the 2 nd time point exceeds a preset threshold value.

2. The cylinder pressure sensor malfunction diagnosis device according to claim 1, characterized in that:

the diagnostic unit makes the threshold smaller than the threshold when the engine speed is low when the engine speed is high.

3. The cylinder pressure sensor malfunction diagnosis device according to claim 1, characterized in that:

the diagnostic unit makes the threshold larger than the threshold when the amount of air filled in the combustion chamber is large than the amount of air in the combustion chamber is small.

4. The cylinder pressure sensor malfunction diagnosis device according to claim 2, characterized in that:

the diagnostic unit makes the threshold larger than the threshold when the amount of air filled in the combustion chamber is large than the amount of air in the combustion chamber is small.

5. The cylinder pressure sensor malfunction diagnosis device according to claim 1, characterized in that:

the determination unit repeatedly performs the comparison between the difference and the threshold;

the determination unit determines that the cylinder pressure sensor is defective when the determination unit determines that the magnitude of the difference exceeds the threshold value is performed a plurality of times in succession.

6. The cylinder pressure sensor malfunction diagnosis device according to claim 2, characterized in that:

the determination unit repeatedly performs the comparison between the difference and the threshold;

the determination unit determines that the cylinder pressure sensor is defective when the determination unit determines that the magnitude of the difference exceeds the threshold value is performed a plurality of times in succession.

7. The cylinder pressure sensor malfunction diagnosis device according to claim 3, characterized in that:

the determination unit repeatedly performs the comparison between the difference and the threshold;

the determination unit determines that the cylinder pressure sensor is defective when the determination unit determines that the magnitude of the difference exceeds the threshold value is performed a plurality of times in succession.

8. The cylinder pressure sensor malfunction diagnosis device according to any one of claims 1 to 7, characterized in that:

the diagnostic unit includes a notification unit that notifies when the determination unit determines that the cylinder pressure sensor has failed.

9. The cylinder pressure sensor malfunction diagnosis device according to any 1 of claims 1 to 7, comprising:

an engine control unit that receives a signal input from a sensing unit including at least the cylinder pressure sensor, and operates the engine based on the signal from the sensing unit;

wherein the engine control portion stops the supply of fuel to the engine when the vehicle running interruption fuel condition is satisfied;

the diagnosing portion performs the failure diagnosis of the cylinder pressure sensor when the engine control portion has stopped supplying fuel to the engine.

10. The cylinder pressure sensor malfunction diagnosis device according to claim 1, comprising:

an ignition unit disposed facing the combustion chamber and configured to ignite the air-fuel mixture in the combustion chamber upon receiving an ignition signal from the engine control unit;

with respect to the air-fuel mixture in the combustion chamber, after a part of the air-fuel mixture starts combustion accompanied by flame propagation by forced ignition in the ignition portion, the remaining unburned air-fuel mixture is combusted by self-ignition;

in order to cause the unburned gas-fuel mixture to spontaneously ignite at a target time point, the engine control portion outputs the ignition signal to the ignition portion before the target time point;

the engine control unit also estimates a point in time at which the unburned gas mixture self-ignites based on a signal of the cylinder pressure sensor.

11. The cylinder pressure sensor malfunction diagnosis device according to claim 8, comprising:

an ignition unit disposed facing the combustion chamber and configured to ignite the air-fuel mixture in the combustion chamber upon receiving an ignition signal from the engine control unit;

with respect to the air-fuel mixture in the combustion chamber, after a part of the air-fuel mixture starts combustion accompanied by flame propagation by forced ignition in the ignition portion, the remaining unburned air-fuel mixture is combusted by self-ignition;

in order to cause the unburned gas-fuel mixture to spontaneously ignite at a target time point, the engine control portion outputs the ignition signal to the ignition portion before the target time point;

the engine control unit also estimates a point in time at which the unburned gas mixture self-ignites based on a signal of the cylinder pressure sensor.

Technical Field

The technology disclosed herein relates to a failure diagnosis device for a cylinder pressure sensor.

Background

Patent document 1 describes an abnormality detection device for a cylinder pressure sensor that detects the pressure in an engine combustion chamber. A cylinder pressure sensor of the device has a deformation portion which deforms in response to a cylinder pressure and a strain gauge which is attached to the deformation portion. If the elastic modulus of the deformation portion is increased by a change in the material composition due to the influence of heat or the like, the elastic deformation is difficult, and the gain of the output value of the cylinder pressure sensor is reduced. Then, the device detects the gain of the output value of the cylinder pressure sensor, and diagnoses that the cylinder pressure sensor is abnormal when the gain is low.

In addition, this apparatus diagnoses an abnormality of the engine when the gain of the output value of the cylinder pressure sensor is low and the output waveform has a deviation in time, and diagnoses no abnormality of the cylinder pressure sensor when the gain of the output value of the cylinder pressure sensor is low and the output waveform has no deviation in time, in order to prevent an erroneous diagnosis.

Disclosure of Invention

Technical problem to be solved by the invention

The invention provides a new idea for the gain of the output value of the cylinder pressure sensor after being studied. Specifically, it has been newly found that when the cylinder pressure sensor is damaged by heat or the like and fails, the symmetry of the signal value of the cylinder pressure sensor is broken, and the detailed mechanism is not clear. At this time, the difference between the signal value of the cylinder pressure sensor at the time point advanced by a certain crank angle with respect to the compression top dead center and the signal value of the cylinder pressure sensor at the time point delayed by the same crank angle with respect to the compression top dead center becomes large.

The present inventors have found that the technique described in patent document 1 considers the gain of the output value of the cylinder pressure sensor, but does not consider the symmetry of the output value at all, and therefore there is room for improvement in the accuracy of the abnormality diagnosis.

The technology disclosed herein can improve the accuracy of cylinder pressure sensor failure diagnosis.

Means for solving the problems

The technology disclosed herein relates to a failure diagnosis device for a cylinder pressure sensor. The failure diagnosis device is provided with: a cylinder pressure sensor that is provided in a combustion chamber of an engine mounted on an automobile and outputs a signal corresponding to a pressure in the combustion chamber; and a diagnosis unit which receives a signal input from the cylinder pressure sensor and diagnoses a failure of the cylinder pressure sensor based on the signal from the cylinder pressure sensor.

Then, the diagnosis unit includes: a reading unit that reads a signal of the cylinder pressure sensor at a 1 st time point that lags behind a specific crank angle with respect to a compression top dead center and a signal of the cylinder pressure sensor at a 2 nd time point that advances the specific crank angle with respect to the compression top dead center; and a determination unit configured to determine that the cylinder pressure sensor is defective when a magnitude of a difference between the signal value of the cylinder pressure sensor at the 1 st time point and the signal value of the cylinder pressure sensor at the 2 nd time point exceeds a preset threshold value.

In this case, the diagnostic unit compares the magnitude of the difference between the signal value of the cylinder pressure sensor at the 1 st time point and the signal value of the cylinder pressure sensor at the 2 nd time point with a preset threshold value. When the magnitude of the difference exceeds a threshold value, the determination unit determines that the cylinder pressure sensor is malfunctioning. This makes it possible to more accurately diagnose a failure of the cylinder pressure sensor.

In addition, it can be designed that: the diagnostic unit makes the threshold smaller than a threshold when the engine speed is low when the engine speed is high.

The difference between the signal value of the cylinder pressure sensor at the 1 st time point and the signal value of the cylinder pressure sensor at the 2 nd time point becomes large under the influence of the cooling loss. Although this influence is not related to the failure of the cylinder pressure sensor, it may become an error factor in diagnosing the failure. Therefore, in order to improve the accuracy of the failure diagnosis of the cylinder pressure sensor, it is effective to set the threshold value to be larger than the increased value due to the cooling loss.

On the other hand, when the engine speed is high, the cooling loss per unit time is small, and therefore the difference is small. Therefore, at this time, it is advantageous to improve the accuracy of the failure diagnosis of the cylinder pressure sensor by setting the threshold value smaller than when the rotation number is low.

In addition, it can be designed that: the diagnostic unit makes the threshold larger than a threshold for a small amount of air in the combustion chamber when the amount of air filled in the combustion chamber is large.

When the amount of air filled in the combustion chamber is large, leakage from the joint of the piston ring during compression of the combustion chamber becomes large, and therefore the pressure in the combustion chamber after compression top dead center becomes low. Thus, the difference between the signal value of the cylinder pressure sensor at the 1 st time point and the signal value of the cylinder pressure sensor at the 2 nd time point may become large. Although this influence is not related to the failure of the cylinder pressure sensor, it may become an error factor in diagnosing the failure. Therefore, in order to improve the accuracy of the failure diagnosis of the cylinder pressure sensor, it is effective to set the threshold value to be larger than or equal to the larger value due to the leakage loss.

With the above configuration, the diagnostic unit increases the threshold value when the amount of air filled in the combustion chamber is large as compared to when the amount of air is small. This is advantageous in more accurately diagnosing the failure of the cylinder pressure sensor.

In addition, it can be designed that: the determination unit repeatedly performs the comparison between the difference and the threshold value, and determines that the cylinder pressure sensor is defective when the determination unit determines that the magnitude of the difference exceeds the threshold value a plurality of times in succession.

For example, if the engagement between the components constituting the cylinder pressure sensor changes during the compression stroke, the pressure in the combustion chamber may decrease after compression top dead center. Such a pressure drop is merely a temporary phenomenon, but may lead to an erroneous diagnosis of the cylinder pressure sensor.

In fact, since the pressure in the combustion chamber continuously changes when the cylinder pressure sensor fails, it is advantageous to perform a failure diagnosis of the cylinder pressure sensor more accurately by repeating the determination by the determination unit as described above.

In addition, it can be designed that: the diagnostic unit includes a notification unit that notifies when the determination unit determines that the cylinder pressure sensor has failed.

Through the technical scheme, after the cylinder pressure sensor is informed of the fault message, the cylinder pressure sensor with the fault can be replaced.

In addition, it can be designed that: the failure diagnosis device for a cylinder pressure sensor includes: an engine control unit that receives a signal input from a sensing unit including at least the cylinder pressure sensor, and operates the engine based on the signal from the sensing unit; wherein the engine control portion stops the supply of fuel to the engine when the vehicle running interruption fuel condition is satisfied; the diagnostic portion performs a failure diagnosis of the cylinder pressure sensor when the engine control portion has stopped supplying fuel to the engine.

When the engine control unit stops supplying fuel to the engine, combustion is not performed in the combustion chamber. The pressure in the combustion chamber, i.e., the signal value of the cylinder pressure sensor, increases and decreases only in accordance with the change in the volume of the combustion chamber. The determination unit can more accurately diagnose the failure of the cylinder pressure sensor based on the difference between the signal value of the cylinder pressure sensor at the 1 st time point and the signal value of the cylinder pressure sensor at the 2 nd time point.

In addition, it can be designed that: the failure diagnosis device for a cylinder pressure sensor includes: an ignition unit disposed facing the inside of the combustion chamber and configured to ignite the air-fuel mixture in the combustion chamber in response to an ignition signal from the engine control unit; with respect to the air-fuel mixture in the combustion chamber, after a part of the air-fuel mixture starts combustion accompanied by flame propagation by forced ignition in the ignition portion, the remaining unburned air-fuel mixture is combusted by self-ignition; in order to cause the unburned gas-fuel mixture to spontaneously ignite at a target time point, the engine control portion outputs the ignition signal to the ignition portion before the target time point; the engine control unit also estimates a point in time at which the unburned gas mixture self-ignites based on a signal from the cylinder pressure sensor.

The applicant proposed SPCCI (spark Controlled Compression ignition) combustion combining SI (spark ignition) combustion with CI (Compression ignition) combustion. SI combustion is combustion accompanied by flame propagation, which is initiated by forced ignition of an air-fuel mixture in a combustion chamber. CI combustion is combustion that is initiated by compression ignition of a mixture in a combustion chamber. In the SPCCI combustion, after the mixture in the combustion chamber is forcibly ignited to start flame propagation combustion, SI combustion generates heat and the pressure rises due to flame propagation, whereby the unburned mixture in the combustion chamber is CI-combusted.

CI combustion occurs when the in-cylinder temperature reaches an ignition temperature depending on the composition of the mixture. Fuel efficiency of SPCCI combustion can be maximized if the in-cylinder temperature reaches the ignition temperature near compression top dead center and CI combustion is generated.

On the other hand, if CI combustion is generated in the SPCCI combustion in the vicinity of the compression top dead center, the in-cylinder pressure may rise excessively, and combustion noise may become excessive. If the ignition timing is retarded at this time, CI combustion occurs at a timing at which the piston has moved down by a considerable amount in the power stroke, and therefore combustion noise can be suppressed. But the fuel efficiency of the engine may be reduced.

In order to improve fuel efficiency performance while suppressing combustion noise in an engine that performs SPCCI combustion, it is necessary to control SPCCI combustion so that a combustion waveform that changes with respect to the advance of the crank angle is an appropriate combustion waveform.

To control the SPCCI combustion, for example, CI combustion start timing θ CI, which is a parameter indicating characteristics of the SPCCI combustion, may be used. The CI combustion start timing θ CI is a timing at which the unburned air-fuel mixture self-ignites. When the actual θ CI is advanced compared to the target θ CI, CI combustion occurs at a time point closer to the compression top dead center, and thus combustion noise increases. To suppress combustion noise, the engine control unit needs to grasp the actual θ ci.

The engine control unit can adjust the ignition timing based on the difference between the actual θ ci and the target θ ci so that the actual θ ci can be brought close to the target θ ci. For example, when the actual θ ci is advanced from the target θ ci, the engine control unit can retard the actual θ ci by retarding the ignition timing, thereby suppressing combustion noise.

The applicant of the present application has also proposed a technique of accurately estimating θ ci based on a signal of the cylinder pressure sensor.

More accurate failure diagnosis of the cylinder pressure sensor can improve fuel efficiency performance while suppressing combustion noise in an engine that performs SPCCI combustion.

Effects of the invention

As described above, the failure diagnosis device for the cylinder pressure sensor can improve the accuracy of diagnosis.

Drawings

FIG. 1 is an exemplary diagram of an engine configuration;

FIG. 2 is a view showing a structural example of a combustor, an upper view is a plan view of the combustor, and a lower view is a sectional view taken along line II-II;

FIG. 3 is a block diagram showing an example of the structure of an engine control device;

FIG. 4 is a sectional explanatory view showing a structural example of a cylinder pressure sensor;

FIG. 5 is an exemplary graph of waveforms for SPCCI combustion;

FIG. 6 is a block diagram showing an example of a functional structure of an engine control unit;

FIG. 7 is a diagram showing an example of variation in intake valve closing timing with respect to engine load;

fig. 8 is a block diagram showing an example of a functional structure related to the failure diagnosis apparatus for the cylinder pressure sensor;

fig. 9 is an exemplary diagram of a signal waveform output when the cylinder pressure sensor is normal and a signal waveform output when there is a failure;

fig. 10 is an example diagram of threshold values involved in the diagnosis of a failure of the pressure difference and the cylinder pressure sensor at normal times;

FIG. 11 is an example plot of pressure differential versus engine load;

fig. 12 is an example graph of the pressure difference corresponding to the EGR gas amount;

FIG. 13A is an exemplary flowchart of a portion of the cylinder pressure sensor fault diagnosis procedure;

FIG. 13B is an exemplary flowchart of additional portions of the cylinder pressure sensor fault diagnosis procedure;

FIG. 14 is a graph in which the upper diagram is a relationship between the number of engine revolutions and the delay period and the lower diagram is a relationship between the number of engine revolutions and the delay time;

FIG. 15 is a graph of example times of changes in various parameters associated with fault diagnosis of a cylinder pressure sensor;

FIG. 16 is a graph of example times of changes in various parameters associated with fault diagnosis of a cylinder pressure sensor;

fig. 17 is an example flowchart of other portions of the failure diagnosing step of the cylinder pressure sensor different from fig. 13B.

Detailed description of the preferred embodiments

The following describes in detail a related embodiment of a failure diagnosis device for a cylinder pressure sensor based on the drawings. The following description is an example of a failure diagnosis device for a cylinder pressure sensor.

Fig. 1 is a diagram showing a structure example of a compression ignition engine having a failure diagnosis device of a cylinder pressure sensor. Fig. 2 is a structural example diagram of a combustion chamber of an engine. In fig. 1, the intake side is the left side of the drawing, and the exhaust side is the right side of the drawing. In fig. 2, the intake side is the right side of the paper, and the exhaust side is the left side of the paper. Fig. 3 is a block diagram showing an example of the structure of the engine control device.

The engine 1 is a 4-stroke reciprocating engine that operates by repeating an intake stroke, a compression stroke, a power stroke, and an exhaust stroke through the combustion chamber 17. The engine 1 is mounted on a four-wheeled vehicle. The engine 1 is operated, whereby the automobile runs. The fuel of the engine 1 is gasoline in this structural example. The fuel may be any liquid fuel including at least gasoline. For example, the fuel may be gasoline containing bioethanol and the like.

(Structure of Engine)

The engine 1 has a cylinder block 12 and a cylinder head 13 mounted on the cylinder block. The cylinder block 12 has a plurality of cylinders 11 formed therein. Fig. 1 and 2 show only one cylinder 11. The engine 1 is a multi-cylinder engine.

The piston 3 is inserted into each cylinder 11 and the piston 3 can slide freely. The piston 3 is connected to a crankshaft 15 via a connecting rod 14. The piston 3 defines a combustion chamber 17 together with the cylinder 11 and the cylinder head 13. In addition, sometimes "combustion chambers" are used in a broad sense. That is, the "combustion chamber" may be a space formed by the piston 3, the cylinder 11, and the cylinder head 13 regardless of the position of the piston 3. In the following description, a word "in-cylinder" having substantially the same meaning as that of the combustion chamber may be used.

The lower surface of the cylinder head 13, i.e., the top surface of the combustion chamber 17, is formed by an inclined surface 1311 and an inclined surface 1312 as shown in the bottom drawing of fig. 2. The inclined surface 1311 is inclined upward from the intake side toward an axis X2 of an injector 6 described later. The inclined surface 1312 is inclined upward from the axis X2 of the exhaust side fuel injector 6. The top surface of the combustion chamber 17 is a so-called roof ridge shape.

The upper side of the piston 3 is raised toward the top surface of the combustion chamber 17. The upper side surface of the piston 3 is formed with a recess 31. The recess 31 is recessed from the upper side surface of the piston 3. The recess 31 is in this construction example shallow disc shaped. The center of the recess 31 is offset to the exhaust side with respect to the central axis X1 of the cylinder 11.

The geometric compression ratio of the engine 1 is set to 10 or more and 30 or less. As will be described later, the engine 1 performs SPCCI combustion in which SI combustion and CI combustion are combined. SPCCI combustion utilizes heat generation and pressure rise generated by SI combustion to control CI combustion. The engine 1 is a compression ignition engine. However, in this engine 1, it is not necessary to increase the temperature of the combustion chamber 17 when the piston 3 reaches compression top dead center. The engine 1 can set the geometric compression ratio to a relatively low value. The lower geometric compression ratio is beneficial for reducing cooling loss and reducing mechanical loss. The geometric compression ratio of the engine 1 can be set to 14 to 17 in the conventional specification (low-octane fuel having a fuel octane number of about 91) and 15 to 18 in the high-octane specification (high-octane fuel having a fuel octane number of about 96).

An intake port 18 is formed in the cylinder head 13 for each cylinder 11. The intake ports 18 include two intake ports 18, a 1 st intake port and a 2 nd intake port, and are not illustrated here. The intake port 18 communicates with the combustion chamber 17. The intake port 18 is a so-called tumble port. That is, the shape of the intake port 18 causes tumble flow to be formed in the combustion chamber 17.

The intake port 18 is provided with an intake valve 21. The intake valve 21 opens and closes between the combustion chamber 17 and the intake port 18. The intake valve 21 is opened and closed at a fixed timing by a valve train. The valve timing mechanism may be a variable valve timing mechanism that varies the valve timing and/or the valve lift. In this configuration example, as shown in fig. 3, the variable Valve gear includes an intake electric motor S-VT (Sequential-Valve Timing) 23. The intake electric motor S-VT 23 continuously changes the phase of the intake camshaft within a certain range. The opening timing and the closing timing of the intake valve 21 are continuously changed. Besides, the air intake and air distribution mechanism can also comprise a hydraulic S-VT to replace the electric S-VT.

Further, the cylinder head 13 is formed with an exhaust port 19 for each cylinder 11. The exhaust ports 19 also include two exhaust ports 19, a 1 st exhaust port and a 2 nd exhaust port. The exhaust port 19 communicates with the combustion chamber 17.

The exhaust port 19 is provided with an exhaust valve 22. The exhaust valve 22 opens and closes between the combustion chamber 17 and the exhaust port 19. The exhaust valve 22 is opened and closed at a fixed timing by a valve train. The valve timing and/or valve lift of the valve mechanism may be variable. In this configuration example, as shown in fig. 3, the variable valve gear includes an exhaust motor S-VT 24. The exhaust motor S-VT 24 continuously changes the phase of the exhaust camshaft within a certain range. The opening timing and the closing timing of the exhaust valve 22 are continuously changed. In addition, the exhaust valve mechanism can also comprise an oil pressure type S-VT instead of an electric S-VT.

The intake electric motor S-VT 23 and the exhaust electric motor S-VT 24 adjust the length of the overlap period during which both the intake valve 21 and the exhaust valve 22 are opened. The long overlap period allows the residual gas in the combustion chamber 17 to be scavenged. It is also possible to introduce internal egr (exhaust Gas recirculation) Gas into the combustion chamber 17 by adjusting the length of the overlap period. The intake electric S-VT 23 and the exhaust electric S-VT 24 constitute an internal EGR system. In addition, the internal EGR system is not limited to being constituted by S-VT.

The cylinder head 13 is provided with an injector 6 for each cylinder 11. The injector 6 injects fuel directly into the combustion chamber 17. The injector 6 is an example of a fuel injection portion. The injector 6 is disposed at the intersection of the inclined surface 1311 and the inclined surface 1312. As shown in fig. 2, the axis X2 of the injector 6 is located on the exhaust side with respect to the central axis X1 of the cylinder 11. The axis X2 of the fuel injector 6 is parallel to the central axis X1. The axis X2 of the injector 6 coincides with the center of the recess 31. The injector 6 faces the recess 31. The axis X2 of the injector 6 may be aligned with the central axis X1 of the cylinder 11. In this configuration, the axis X2 of the injector 6 may be aligned with the center of the recess 31.

The injector 6 is constituted by a multi-nozzle type fuel injection valve having a plurality of nozzle holes, and a detailed illustration thereof is omitted. As shown by the two-dot chain line in fig. 2, the injector 6 injects fuel and spreads the fuel spray radially from the center of the combustion chamber 17. In this structural example, the injector 6 has 10 injection holes arranged at equal angles in the circumferential direction.

The injector 6 is connected to a fuel supply system 61. The fuel supply system 61 includes a fuel tank 63 and a fuel supply line 62 connecting the fuel tank 63 and the injector 6. The fuel tank 63 stores fuel. The fuel supply path 62 is provided with a fuel pump 65 and a common rail 64. Fuel pump 65 delivers fuel to common rail 64 by pressure. The fuel pump 65 is a plunger-type pump driven by the crankshaft 15 in this configuration example. The common rail 64 stores high-pressure fuel delivered from a fuel pump 65 by pressure. After the injectors 6 are opened, the fuel stored in the common rail 64 is injected from the injection holes of the injectors 6 into the combustion chamber 17. The fuel supply system 61 can supply high-pressure fuel of 30MPa or more to the injectors 6. The pressure of the fuel supplied to the injectors 6 may also be changed in accordance with the operating state of the engine 1. In addition, the structure of the fuel supply system 61 is not limited to the structure.

The cylinder head 13 is provided with an ignition plug 25 for each cylinder 11. The ignition plug 25 forcibly ignites the mixture in the combustion chamber 17. The ignition plug 25 is an example of an ignition portion. In this configuration example, the ignition plug 25 is disposed on the intake side with respect to the center axis X1 of the cylinder 11. The ignition plug 25 is located between the two intake ports 18. The ignition plug 25 is mounted on the cylinder head 13 and is inclined so as to be closer to the center of the combustion chamber 17 from the top down. As shown in fig. 2, the electrode of the ignition plug 25 faces into the combustion chamber 17 and is located near the top surface of the combustion chamber 17. The ignition plug 25 may be disposed on the exhaust side with respect to the central axis X1 of the cylinder 11. The ignition plug 25 may be disposed on the center axis X1 of the cylinder 11.

An intake passage 40 is connected to one side surface of the engine 1. The intake passage 40 communicates with the intake port 18 of each cylinder 11. Gas to be introduced into the combustion chamber 17 flows through the intake passage 40. An air cleaner 41 is disposed at an upstream end of the intake passage 40. The air cleaner 41 filters fresh air. A surge tank 42 is disposed near the downstream end of the intake passage 40. The intake passage 40 downstream of the surge tank 42 is an independent passage that is branched separately corresponding to each cylinder 11. The downstream end of the independent passage is connected to the intake port 18 of each cylinder 11.

A throttle valve 43 is disposed in the intake passage 40 between the air cleaner 41 and the surge tank 42. The throttle valve 43 adjusts the amount of fresh air introduced into the combustion chamber 17 by adjusting the valve opening.

A supercharger 44 is disposed downstream of the throttle valve 43 in the intake passage 40. The supercharger 44 supercharges the gas to be introduced into the combustion chamber 17. In this configuration example, the supercharger 44 is a mechanical supercharger driven by the engine 1. The mechanical supercharger 44 may be Roots (Roots), double helical rod (Lysholm), sliding vane, or centrifugal.

An electromagnetic clutch 45 is provided between the supercharger 44 and the engine 1. The electromagnetic clutch 45 is provided between the supercharger 44 and the engine 1, and transmits or blocks transmission of the driving force from the engine 1 to the supercharger 44. As described later, the ECU10 switches the electromagnetic clutch 45 between the blocking state and the connecting state, thereby switching the supercharger 44 between the on state and the off state.

An intercooler 46 is disposed in the intake passage 40 downstream of the supercharger 44. The intercooler 46 is used to cool the compressed air of the supercharger 44. The intercooler 46 may be, for example, water-cooled or oil-cooled.

The bypass passage 47 is connected to the intake passage 40. The bypass passage 47 interconnects an upstream portion of the supercharger 44 and a downstream portion of the intercooler 46 in the intake passage 40. The bypass passage 47 bypasses the supercharger 44 and the intercooler 46. A gas bypass valve 48 is disposed in the bypass passage 47. The gas bypass valve 48 adjusts the flow rate of the gas flowing through the bypass passage 47.

The ECU10 fully opens the gas bypass valve 48 when the supercharger 44 is closed (i.e., when the electromagnetic clutch 45 is off). The gas flowing in the intake passage 40 bypasses the supercharger 44 and enters the combustion chamber 17 of the engine 1. The engine 1 is operated in a non-supercharged, i.e. naturally aspirated, state.

The engine 1 is operated in a supercharged state after the supercharger 44 is opened. The ECU10 adjusts the opening degree of the gas bypass valve 48 when the supercharger 44 is open (i.e., the electromagnetic clutch 45 is connected). A part of the gas having passed through the supercharger 44 flows backward to the upstream of the supercharger 44 through the bypass passage 47. When the ECU10 adjusts the opening degree of the gas bypass valve 48, the pressure of the gas entering the combustion chamber 17 changes. That is, the boost pressure may change. Can be defined as: the pressurization time means a time when the pressure in the buffer tank 42 exceeds the atmospheric pressure, and the non-pressurization time means a time when the pressure in the buffer tank 42 is equal to or lower than the atmospheric pressure.

In this configuration example, the supercharger 44, the bypass passage 47, and the gas bypass valve 48 constitute a supercharging system 49.

The engine 1 includes a vortex flow generating portion that generates a vortex flow in the combustion chamber 17. The vortex flows as indicated by the hollow arrows in fig. 2. The swirl generating portion includes a swirl control valve 56 attached to the intake passage 40. The swirl control valve 56 is disposed in a first passage connected to one of the two intake ports 18 and a second passage connected to the other intake port 18, and is not shown in detail. The swirl control valve 56 is an opening degree adjustment valve capable of reducing the cross section of the second passage. The swirl control valve 56 is opened small, so that the flow rate of intake air into the combustion chamber 17 from one intake port 18 is relatively large and the flow rate of intake air into the combustion chamber 17 from the other intake port 18 is relatively small, and therefore the swirl in the combustion chamber 17 is increased. When the opening degree of the swirl control valve 56 is large, the flow rates of intake air from the two intake ports 18 into the combustion chamber 17 are substantially equal, and therefore the swirl in the combustion chamber 17 becomes weak. Full opening of the swirl control valve 56 produces no swirl.

An exhaust passage 50 is connected to the other side surface of the engine 1. The exhaust passage 50 communicates with the exhaust port 19 of each cylinder 11. The exhaust passage 50 is a passage through which exhaust gas discharged from the combustion chamber 17 flows. The upstream portion of the exhaust passage 50 is an independent passage that branches off for each cylinder 11, and is not shown in detail. The upstream end of the independent passage is connected to an exhaust port 19 of each cylinder 11.

The exhaust passage 50 is provided with an exhaust gas purification system including a plurality of catalytic converters. The upstream catalytic converter is disposed in the engine compartment, and is not shown. The upstream catalytic converter includes a three-way catalyst 511, gpf (gasolinparticulate filter) 512. The downstream catalytic converter is disposed outside the engine compartment. The downstream catalytic converter includes a three-way catalyst 513. In addition, the exhaust gas purification system is not limited to the illustrated structure. For example, GPF may also be omitted. In addition, the catalytic converter is not limited to a catalytic converter including a three-way catalyst. The order of arrangement of the three-way catalyst and the GPF may be changed as appropriate.

An EGR passage 52 is connected between the intake passage 40 and the exhaust passage 50. The EGR passage 52 is a passage that recirculates a part of the exhaust gas to the intake passage 40. The EGR passage 52 constitutes an external EGR system. The upstream end of the EGR passage 52 is connected between the upstream catalytic converter and the downstream catalytic converter in the exhaust passage 50. The downstream end of the EGR passage 52 is connected to the portion of the intake passage 40 upstream of the supercharger 44. The EGR gas flowing through the EGR passage 52 does not pass through the gas bypass valve 48 of the bypass passage 47, but enters the intake passage 40 upstream of the supercharger 44.

A water-cooled EGR cooler 53 is disposed in the EGR passage 52. The EGR cooler 53 cools the exhaust gas. Further, an EGR valve 54 is disposed in the EGR passage 52. The EGR valve 54 adjusts the flow rate of the exhaust gas flowing in the EGR passage 52. The amount of recirculation of the cooled exhaust gas, i.e., the external EGR gas, can be adjusted by adjusting the opening degree of the EGR valve 54.

The EGR system 55 in the engine 1 includes an external EGR system and an internal EGR system. The external EGR system can supply exhaust gas of a lower temperature than the internal EGR system to the combustion chamber 17.

The Control apparatus of the compression ignition engine includes an ecu (engine Control unit) 10 that operates the engine 1. The ECU10 is a control unit based on a known microcomputer, and as shown in fig. 3, includes: a microcomputer 101 including a Central Processing Unit (CPU) for executing a program; a memory 102 for storing programs and data, which is constituted by, for example, a ram (random access memory) and a rom (read Only memory); an I/F circuit 103 for inputting and outputting an electric signal.

As shown in fig. 1 and 3, various sensors SW1 to SW17 are connected to the ECU 10. The sensors SW1 to SW17 output signals to the ECU 10. The sensors include the following.

Air flow sensor SW 1: disposed downstream of the air cleaner 41 in the intake passage 40, and outputting a signal corresponding to the flow rate of fresh air flowing through the intake passage 40

1 st intake air temperature sensor SW 2: disposed downstream of the air cleaner 41 in the intake passage 40, and outputting a signal corresponding to the temperature of fresh air flowing through the intake passage 40

1 st pressure sensor SW 3: a signal corresponding to the pressure of the gas to be introduced into the supercharger 44 is output upstream of the supercharger 44 and downstream of the connection position of the EGR passage 52 in the intake passage 40

2 nd intake air temperature sensor SW 4: a signal corresponding to the temperature of the gas flowing out of the supercharger 44 is output and disposed downstream of the supercharger 44 in the intake passage 40 and upstream of the connection position of the bypass passage 47

Intake pressure sensor SW 5: a buffer tank 42 for outputting a signal corresponding to the gas pressure downstream of the supercharger 44

Cylinder pressure sensor SW 6: mounted to the cylinder head 13 corresponding to each cylinder 11, and outputting a signal corresponding to the pressure in each combustion chamber 17

Exhaust gas temperature sensor SW 7: is disposed in the exhaust passage 50 and outputs a signal corresponding to the temperature of the exhaust gas discharged from the combustion chamber 17

Linear oxygen (linearO)₂) Sensor SW 8: disposed upstream of the upstream catalytic converter in the exhaust passage 50, and outputting a signal corresponding to the oxygen concentration in the exhaust gas

Oxygen (lamb dao 2) sensor SW 9: a three-way catalyst 511 disposed downstream of the upstream catalytic converter and outputting a signal corresponding to the oxygen concentration in the exhaust gas

Water temperature sensor SW 10: mounted on the engine 1, outputting a signal corresponding to the temperature of the cooling water

Crank angle sensor SW 11: mounted on the engine 1 and outputting a signal corresponding to the angle of rotation of the crankshaft 15

Accelerator opening degree sensor SW 12: an accelerator pedal mechanism mounted on the vehicle and outputting a signal corresponding to an accelerator opening proportional to an amount of operation of the accelerator pedal

Intake cam position sensor SW 13: mounted on the engine 1, outputting a signal corresponding to the rotation angle of the intake camshaft

Exhaust cam position sensor SW 14: mounted on the engine 1, outputting a signal corresponding to the rotation angle of the exhaust camshaft

EGR differential pressure sensor SW 15: disposed in the EGR passage 52, and outputting signals corresponding to differential pressures upstream and downstream of the EGR valve 54

Fuel pressure sensor SW 16: a common rail 64 installed in the fuel supply system 61 and outputting a signal corresponding to the pressure of fuel supplied to the injector 6

Intake air temperature sensor No. 3 SW 17: mounted to the buffer tank 42, outputs a signal corresponding to the temperature of the gas in the buffer tank 42, in other words, the temperature of the intake air entering the combustion chamber 17.

The ECU10 determines the operation state of the engine 1 based on the signals from the sensors SW1 to SW17, and calculates the control amount of each device according to a preset control logic. The control logic is stored in memory 102. The control logic includes a target amount and/or a control amount using the mapping operation stored in the memory 102.

The ECU10 outputs electric signals corresponding to the calculated control amounts to the injector 6, the ignition plug 25, the intake motor S-VT 23, the exhaust motor S-VT 24, the fuel supply system 61, the throttle valve 43, the EGR valve 54, the electromagnetic clutch 45 of the supercharger 44, the gas bypass valve 48, and the swirl control valve 56.

For example, the ECU10 sets a target torque of the engine 1 based on the signal of the accelerator opening sensor SW12 and a map, and determines a target supercharging pressure. The ECU10 then performs feedback control for adjusting the opening degree of the gas bypass valve 48 based on the target supercharging pressure and the differential pressure between the front and rear of the supercharger 44 obtained from the signals of the 1 st pressure sensor SW3 and the intake pressure sensor SW 5. By this feedback control, the supercharging pressure reaches the target supercharging pressure.

In addition, the ECU10 sets a target EGR rate (i.e., the ratio of EGR gas with respect to the entire gas in the combustion chambers 17) according to the operating state of the engine 1 and the map. The ECU10 then determines a target EGR gas amount from the target EGR rate and the intake air amount based on the signal from the accelerator opening sensor SW12, and performs feedback control for adjusting the opening of the EGR valve 54 based on the differential pressure across the EGR valve 54 obtained from the signal from the EGR differential pressure sensor SW 15. The external EGR gas amount that enters the combustion chamber 17 is brought to the target EGR gas amount by this feedback control.

Further, the ECU10 executes air-fuel ratio feedback control when a certain control condition is satisfied. Specifically, the ECU10 adjusts the fuel injection amount of the injector 6 based on the oxygen concentration in the exhaust gas obtained from the signals of the linear oxygen sensor SW8 and the oxygen (LambdaO 2) sensor SW9 so that the air-fuel ratio of the mixture becomes a desired value.

The ECU10 controls the engine 1 in detail as described later.

The ECU10 is also connected to the notification unit 57. The notification unit 57 is constituted by, for example, a warning lamp provided in the instrument panel. As will be described later, the failure diagnosis device 100 of the cylinder pressure sensor SW6 diagnoses the failure of the cylinder pressure sensor SW6, and the notification unit 57 notifies the user.

(Structure of Cylinder pressure sensor)

Fig. 4 is a structural example of the cylinder pressure sensor SW 6. The cylinder pressure sensor SW6 includes a diaphragm 71 disposed facing the inside of the combustion chamber 17. The diaphragm 71 is made of a material having elasticity. The diaphragm 71 is disposed at the tip of the cylinder pressure sensor SW 6. The peripheral portion of the diaphragm 71 is supported by the housing. The housing includes an outer housing 72 and an inner housing 73. When the pressure in the combustion chamber 17 increases, the outer surface of the diaphragm 71 is pressed, and the central portion of the diaphragm 71, which is not supported by the outer casing 72 and the inner casing 73, is bent.

The outer housing 72 is fixed to the cylinder head 13 of the engine 1, and is not shown. The outer case 72 is cylindrical with an open front end. The diaphragm 71 is mounted to the front end surface of the outer case 72. The peripheral portion of the diaphragm 71 is fixed to the outer case 72 by welding.

The inner housing 73 is inserted into the outer housing 72. The inner housing 73 is located at the front end of the outer housing 72. The inner housing 73 is formed by assembling a plurality of parts. The inner housing 73 is also cylindrical. The peripheral portion of the diaphragm 71 is also fixed to the inner housing 73 by welding.

The force toward the front end of the cylinder pressure sensor SW6 is applied to the inner housing 73 by the urging member 74. The biasing member 74 is disposed on the base end side (i.e., the upper side in fig. 4) of the cylinder pressure sensor SW6 with respect to the inner housing 73 inside the outer housing 72.

The inner case 73 is provided with a piezoelectric device 75 inside. The piezoelectric device 75 is deformed by the diaphragm 71 being bent, and outputs a weak current according to the amount of deformation.

A base 76 is attached to the front end of the piezoelectric device 75. The center portion of the base 76 includes a projection 761 projecting toward the front end of the cylinder pressure sensor SW 6. The projection 761 is positioned in a through hole 731 provided in the front end of the inner case 73.

A center protrusion 711, which is integrated with the diaphragm 71 and protrudes toward the base end of the cylinder pressure sensor SW6, is provided at the center portion of the inner surface of the diaphragm 71. The center protrusion 711 of the diaphragm 71 and the projection 761 of the base 76 abut against each other. When the center portion of the diaphragm 71 is bent, the base 76 is pressed toward the base end of the cylinder pressure sensor SW6 by the center protrusion 711, and the piezoelectric device 75 is deformed.

The base end portion of the piezoelectric device 75 is mounted with an electrode 77. A weak current of the piezoelectric device 75 is output through the electrode 77.

The proximal end portion of the electrode 77 is supported by an electrode support portion 78. The electrode support portion 78 is also composed of a combination of a plurality of members. The electrode support portion 78 is welded to the inner case 73. The electrode support portion 78 has a conductive portion 79 disposed therein. The conductive portion 79 extends toward the base end of the cylinder pressure sensor SW 6. The base end of the conductive portion 79 is connected to the charge amplifier 710 of the cylinder pressure sensor SW 6. The charge amplifier 710 amplifies the weak current of the piezoelectric device 75 and outputs it to the ECU 10.

A compression spring 791 is disposed between the electrode 77 and the conductive portion 79. The compression spring 791 allows electrical conduction between the electrode 77 and the conductive portion 79.

An annular insulating portion 712 is provided between the integrated base 76, piezoelectric device 75, and electrode 77 and inner case 73. The insulating portion 712 is a portion colored black in fig. 4.

(concept of SPCCI Combustion)

The engine 1 is mainly designed to improve fuel efficiency and exhaust gas performance and burn in a compression self-ignition manner in a certain operating state. With respect to the self-ignition type combustion, if the temperature in the combustion chamber 17 is uneven before the start of compression, the self-ignition time point greatly changes. The engine 1 thus performs SPCCI combustion combining SI combustion and CI combustion.

SPCCI combustion is the following morphology: the ignition plug 25 forcibly ignites the air-fuel mixture in the combustion chamber 17, whereby the air-fuel mixture undergoes SI combustion by flame propagation, and the heat generation of the SI combustion causes the temperature in the combustion chamber 17 to increase, and the flame propagation causes the pressure in the combustion chamber 17 to rise, whereby the unburned air-fuel mixture realizes CI combustion in an auto-ignition manner.

The difference in temperature in the combustion chamber 17 before the start of compression can be absorbed by adjusting the calorific value of the SI combustion. The air-fuel mixture is caused to self-ignite at the target timing by adjusting the ignition timing by the ECU 10.

In SPCCI combustion, heat generated at SI combustion is smoother than that generated at CI combustion. In terms of the heat generation rate (dQ/d θ) waveform of the SPCCI combustion, as in the example of fig. 5, the inclination of the rise is smaller compared to the inclination of the rise of the CI combustion waveform. In addition, the rate of pressure change (dp/d θ) in the combustion chamber 17 is smoother in SI combustion than in CI combustion.

When the unburned air-fuel mixture self-ignites after the SI combustion starts, the inclination of the heat generation rate waveform may change from small to large at the time point of self-ignition. Sometimes the waveform of the heat generation rate may appear at the inflection point X at the CI combustion start time point.

SI combustion is performed in parallel with CI combustion after CI combustion is started. CI combustion generates more heat than SI combustion, and thus the heat generation rate is relatively large. However, since CI combustion is performed after the compression top dead center, the inclination of the heat generation rate waveform can be prevented from being excessively large. The pressure fluctuation rate (dp/d theta) at the time of CI combustion is also relatively smooth.

The pressure fluctuation rate (dp/d θ) can be used as an index indicating combustion noise. As described above, the SPCCI combustion can make the pressure fluctuation rate (dp/d θ) small, and therefore can prevent excessive combustion noise. The combustion noise of the engine 1 is controlled below an allowable level.

CI combustion ends, whereby SPCCI combustion ends. The CI combustion is shorter in combustion period than the SI combustion. The SPCCI combustion ends earlier than the SI combustion.

The 1 st heat generation rate portion QSI formed by SI combustion and the 2 nd heat generation portion QCI formed by CI combustion are sequentially continuous, forming a heat generation rate waveform of SPCCI combustion.

The SI rate is defined herein as a parameter representing the combustion characteristics of the SPCCI. The applicant defines the SI rate as: an index of the proportion of the heat generated by SI combustion among the total heat generated by SPCCI combustion. The SI rate is a ratio of heat generated by two kinds of combustion having different combustion forms. The higher the SI rate, the higher the SI combustion ratio, and the lower the SI rate, the higher the CI combustion ratio. The high proportion of SI combustion in SPCCI combustion is beneficial to inhibiting combustion noise. The high proportion of CI combustion in the SPCCI combustion is advantageous for improving the fuel efficiency of the engine 1.

The SI rate may also be defined as the ratio of the amount of heat generated by SI combustion relative to the amount of heat generated by CI combustion. Namely, the following scheme can be adopted: in waveform 801 shown in fig. 5, the crank angle at which CI combustion starts in SPCCI combustion is defined as CI combustion start time θ CI, the area of θ CI advance side SI combustion is defined as QSI, the area of retard side CI combustion including θ CI is defined as QCI, and the SI rate is defined as QSI/QCI.

(control logic of Engine)

Fig. 6 is a block diagram showing an example of the functional structure of the ECU10 that executes the control logic of the engine 1. The ECU10 operates the engine 1 in accordance with control logic stored in the memory 102. Specifically, the ECU10 determines the operating state of the engine 1 based on the signals from the sensors SW1 to SW17, and performs calculations to adjust the state quantity, the injection timing, and the ignition timing in the combustion chamber 17, so that the combustion in the combustion chamber 17 is at the SI rate corresponding to the operating state.

The ECU10 controls SPCCI combustion using two parameters, SI rate, θ ci. Specifically, the ECU10 sets a target SI rate and a target θ ci according to the operating state of the engine 1, adjusts the temperature in the combustion chamber 17, and adjusts the ignition timing so that the actual SI rate coincides with the target SI rate and the actual θ ci is equal to the target θ ci. The temperature in the combustion chamber 17 is adjusted by adjusting the temperature and/or amount of the exhaust gas entering the combustion chamber 17.

First, the ECU10 reads signals of the sensors SW1 to SW17 through the I/F circuit 103. Then, the target SI rate/target θ CI setting portion 101a in the microcomputer 101 of the ECU10 determines the operating state of the engine 1 based on the signals of the sensors SW1 to SW17, and sets the target SI rate (i.e., the target heat rate) and the target CI combustion start timing θ CI. The target SI rate is determined according to the operating state of the engine 1. The target SI rate is stored in a target SI rate storage unit 1021 of the memory 102. The target SI rate/target θ ci setting unit 101a sets a low target SI rate when the load on the engine 1 is low, and sets a high target SI rate when the load on the engine 1 is high. When the load of the engine 1 is low, the proportion of CI combustion in SPCCI combustion is increased to suppress combustion noise and improve fuel efficiency performance. When the load of the engine 1 is high, the ratio of SI combustion in SPCCI combustion is increased, and combustion noise is favorably suppressed.

As described above, θ CI means the crank angle time point at which CI combustion starts in SPCCI combustion (see fig. 5). The target θ ci is also set in accordance with the operating state of the engine 1. The target θ ci is stored in the target θ ci storage unit 1022 of the memory 102. The combustion noise is small when θ ci is on the retard side. The fuel efficiency performance of the engine 1 is improved with θ ci on the advance side. The target θ ci is set on the advance side as much as possible within a range in which combustion noise can be suppressed to an allowable level or less.

The target in-cylinder state quantity setting unit 101b sets a target in-cylinder state quantity for achieving the set target SI rate and target θ ci based on the model stored in the memory 102. Specifically, the target in-cylinder state quantity setting unit 101b sets the target temperature, the target pressure, and the target state quantity in the combustion chamber 17.

The in-cylinder state quantity control portion 101c sets the opening degree of the EGR valve 54, the opening degree of the throttle valve 43, the opening degree of the gas bypass valve 48, the opening degree of the swirl control valve 56, the phase angle of the intake electromotive force S-VT 23 (i.e., the valve timing of the intake valve 21), and the phase angle of the exhaust electromotive force S-VT 24 (i.e., the valve timing of the exhaust valve 22) required to achieve the target in-cylinder state quantity. The in-cylinder state amount control unit 101c sets the control amounts of these devices based on the map stored in the memory 102. The in-cylinder state quantity control unit 101c outputs control signals to the EGR valve 54, the throttle valve 43, the gas bypass valve 48, the Swirl Control Valve (SCV) 56, the intake motor S-VT 23, and the exhaust motor S-VT 24 based on the set control quantities. Each apparatus performs work based on the signal of the ECU10, whereby the state quantity in the combustion chamber 17 reaches the target state quantity.

The in-cylinder state quantity control unit 101c also calculates a predicted value of the state quantity in the combustion chamber 17 and an estimated value of the state quantity based on the set control quantities of the respective devices. The state quantity predicted value is a value predicted from the state quantity in the combustion chamber 17 before the intake valve 21 closes. As described later, the state quantity predicted value is used to set the injection quantity of fuel in the intake stroke. The state quantity estimated value is a value obtained by estimating the state quantity in the combustion chamber 17 after the intake valve 21 is closed. As described later, the state quantity estimated value is used to set the injection quantity and ignition timing of fuel in the compression stroke.

The 1 st injection amount setting unit 101d sets the injection amount of fuel in the intake stroke based on the state amount predicted value. When split injection is performed in the intake stroke, the injection amount of each injection is set. When fuel injection is not performed in the intake stroke, the 1 st injection amount setting unit 101d sets the fuel injection amount to 0. The 1 st injection control unit 101e outputs a control signal to the injector 6 to cause the injector 6 to inject fuel into the combustion chamber 17 at a fixed injection timing. Further, the 1 st injection control portion 101e outputs the result of fuel injection in the intake stroke.

The 2 nd injection amount setting portion 101f sets the injection amount of fuel in the compression stroke based on the state amount estimated value and the injection result of fuel in the intake stroke. When fuel injection is not performed in the compression stroke, the 2 nd injection amount setting unit 101f sets the fuel injection amount to 0. The 2 nd injection control portion 101g outputs a control signal to the injector 6, and injects fuel into the combustion chamber 17 using the injector 6 at an injection timing based on a map set in advance. Further, the 2 nd injection control portion 101g outputs the result of the fuel injection in the compression stroke.

The ignition timing setting portion 101h sets the ignition timing based on the state quantity estimated value and the result of injection of fuel in the compression stroke. The ignition control portion 101i outputs a control signal to the ignition plug 25 so that the ignition plug 25 ignites the air-fuel mixture in the combustion chamber 17 at the set ignition timing.

Here, the ignition timing setting portion 101h predicts that the temperature in the combustion chamber 17 is lower than the target temperature based on the state quantity estimated value, and advances the injection timing in the compression stroke to the injection timing based on the map so that the ignition timing can be advanced. Further, if the ignition timing setting unit 101h predicts that the temperature in the combustion chamber 17 is higher than the target temperature based on the state quantity estimated value, the injection timing in the compression stroke is retarded from the injection timing based on the map so that the ignition timing can be retarded.

That is, when the temperature in the combustion chamber 17 is low, the point of time when the unburned air-fuel mixture self-ignites after the SI combustion is started by the spark ignition (CI combustion start time θ CI) is delayed, and the SI rate deviates from the target SI rate. In this case, the unburned fuel increases and the exhaust gas performance deteriorates.

In this regard, when it is predicted that the temperature in the combustion chamber 17 is lower than the target temperature, the 1 st injection control unit 101e and/or the 2 nd injection control unit 101g advances the injection timing, and the ignition timing setting unit 101h advances the ignition timing. Since SI combustion starts early and sufficient heat is generated by SI combustion, the autoignition time point θ ci of the unburned air-fuel mixture can be prevented from being delayed when the temperature in the combustion chamber 17 is low. Therefore, θ ci approaches the target θ ci and the SI rate approaches the target SI rate.

When the temperature in the combustion chamber 17 is high, the unburned air-fuel mixture is spontaneously combusted quickly after SI combustion is started by spark ignition, and the SI rate deviates from the target SI rate. At this time, combustion noise increases.

Here, when it is predicted that the temperature in the combustion chamber 17 is higher than the target temperature, the 1 st injection control unit 101e and/or the 2 nd injection control unit 101g retard the injection timing, and the ignition timing setting unit 101h retards the ignition timing. The SI combustion starts late and the autoignition time point θ ci of the unburned mixture is prevented from advancing at a high temperature in the combustion chamber 17. Therefore, θ ci approaches the target θ ci and the SI rate approaches the target SI rate.

The ignition plug 25 ignites the air-fuel mixture, whereby SI combustion or SPCCI combustion is performed in the combustion chamber 17. The cylinder pressure sensor SW6 measures a change in pressure in the combustion chamber 17.

The measurement signal of the cylinder pressure sensor SW6 is input to the θ ci deviation calculation unit 101 k. The θ CI deviation calculation unit 101k estimates the CI combustion start timing θ CI based on the measurement signal of the cylinder pressure sensor SW6, and calculates a deviation between the estimated CI combustion start timing θ CI and the target θ CI. The θ ci deviation calculation unit 101k outputs the calculated θ ci deviation to the target in-cylinder state quantity setting unit 101 b. The target in-cylinder state quantity setting unit 101b corrects the model based on the θ ci deviation. The target in-cylinder state quantity setting unit 101b sets the target in-cylinder state quantity using the corrected model in the next and subsequent cycles.

The control logic of the engine 1 is adjusted by state quantity setting devices including the throttle valve 43, the EGR valve 54, the gas bypass valve 48, the swirl control valve 56, the intake motor S-VT 23, and the exhaust motor S-VT 24 so that the SI rate and θ ci correspond to the operating state of the engine 1.

Fig. 7 shows a change in the closing timing IVC of the intake valve 21 according to the load of the engine 1 as an example of control of the state amount setting device. In this figure, the closing timing IVC of the intake valve 21 is advanced further upward. Since the intake valve 21 closing timing IVC is advanced and the intake valve 21 opening timing IVC is also advanced, the positive overlap period during which both the intake valve 21 and the exhaust valve 22 are opened is lengthened. The amount of EGR gas introduced into the combustion chamber 17 increases.

Here, when the engine 1 is in the specific operating state, the engine is operated in a state where the a/F of the mixture is made equal to the stoichiometric air-fuel ratio or substantially equal to the stoichiometric air-fuel ratio and the G/F is made leaner than the stoichiometric air-fuel ratio. Thereby, the engine 1 ensures the purification performance of the exhaust gas using the three-way catalyst, and improves the fuel efficiency performance. The fuel supply amount is small when the engine 1 is low in load. When the engine 1 is low in load, the ECU10 sets the closing timing IVC of the intake valve 21 to the retarded side timing. The amount of air taken into the combustion chamber 17 is restricted to correspond to a smaller fuel supply amount. In addition, the amount of EGR gas introduced into the combustion chamber 17 is also limited and thus combustion stability is ensured.

The load of the engine 1 increases, the fuel supply amount increases, and therefore the combustion stability improves. The ECU10 sets the closing timing IVC of the intake valve 21 to the timing on the advance side. The amount of air taken into the combustion chamber 17 increases and the amount of EGR gas taken into the combustion chamber 17 increases.

When the load of the engine 1 becomes higher, the temperature in the combustion chamber 17 becomes higher. To prevent the temperature in the combustion chamber 17 from being excessively high, the amount of internal EGR gas is reduced, and the amount of external EGR gas is increased. The ECU10 thus sets the closing timing IVC of the intake valve 21 to the retarded side timing again.

When the load of the engine 1 is further increased, the fuel supply amount is increased. The supercharger 44 supercharges a large fuel supply amount in order to introduce an amount of air into the combustion chamber 17, the amount of air being such that the a/F of the air-fuel mixture becomes equal to or substantially equal to the stoichiometric air-fuel ratio. When the supercharger 44 supercharges, the ECU10 again sets the closing timing of the intake valve 21 to the timing on the advance side. Since the amount of air taken into the combustion chamber 17 increases and a positive overlap period is provided in which both the intake valve 21 and the exhaust valve 22 are opened, the residual gas in the combustion chamber 17 can be scavenged.

The control logic of the engine 1 roughly adjusts the SI rate by adjusting the state quantity in the combustion chamber 17 as described above. The control logic of the engine 1 adjusts the SI rate and θ ci by adjusting the fuel injection timing and the ignition timing. The adjustment of the injection and ignition timings allows, for example, the correction of the differences between the cylinders and the fine adjustment of the autoignition times. Through the two-stage SI rate adjustment, the engine 1 can correctly achieve the target SPCCI combustion corresponding to the operating state.

(Combustion noise suppression control)

The SPCCI combustion is a combustion form combining SI combustion and CI combustion, and therefore knocking by SI combustion and knocking by CI combustion are both likely to occur. The knocking by the SI combustion is referred to as SI knocking, the knocking by the CI combustion is referred to as CI knocking, the SI knocking is a phenomenon of abnormal local autoignition (local autoignition significantly different from normal CI combustion) of the unburned gas outside the region where the air-fuel mixture SI is burned in the combustion chamber 17 and thus rapid combustion, and the CI knocking is a phenomenon in which the CI combustion causes pressure variation and causes resonance of the main parts (cylinder block/head, piston, crank journal portion, etc.) of the engine 1. With respect to SI knocking, which occurs as loud noise having a frequency of about 6.3 kHz, local auto-ignition causes generation of air column vibration in the combustion chamber 17. The CI knock is affected by resonance of the main components of the engine 1, and the CI knock occurs as loud noise having a frequency of about 1 to 4kHz (more strictly, a plurality of frequencies included in the range). As described above, SI knocking and CI knocking occur as noises of different frequencies due to different causes.

The ECU10 controls the SPCCI combustion so that neither SI knocking nor CI knocking occurs. Specifically, the ECU10 calculates an SI knock index value associated with SI knock and a CI knock index value associated with CI knock by fourier-converting the detection signal of the cylinder pressure sensor SW 6. The SI knock index value is an in-cylinder pressure spectrum around 6.3 kHz that increases with the generation of SI knock, and the CI knock index value is an in-cylinder pressure spectrum around 1-4 kHz that increases with the generation of CI knock.

Then, the ECU10 determines a θ CI limit such that neither the SI knock index value nor the CI knock index value exceeds the allowable limit according to a preset map, compares the θ CI determined according to the operating state of the engine 1 with the θ CI limit, and determines the θ CI as the target θ CI if the θ CI limit is the same as or on the advance side of the θ CI, and determines the θ CI as the target θ CI if the θ CI limit is on the retard side of the θ CI. SI knocking and CI knocking are suppressed by such control.

(failure diagnosis of Cylinder pressure sensor)

The engine 1 that performs the SPCCI combustion performs ignition control and combustion noise suppression control using the detection signal of the cylinder pressure sensor SW6 as described above. The detection signal of the cylinder pressure sensor SW6 in the engine 1 is important. The operation control of the engine 1 may be affected if the cylinder pressure sensor SW6 malfunctions and causes an erroneous sensing signal to be output. The engine 1 therefore includes the failure diagnosis device 100 of the cylinder pressure sensor SW 6.

Fig. 8 is a structural example of the failure diagnosis device 100 of the cylinder pressure sensor SW 6. The failure diagnosis device 100 includes a diagnosis unit 111 and an engine control unit 112. The diagnostic unit 111 and the engine control unit 112 are functional modules that are configured in the ECU 10. The engine control unit 112 controls the operation of the engine 1. Here, the engine control unit 112 performs fuel cut control of the engine 1. Specifically, the engine control unit 112 stops the supply of fuel to the engine 1 by the injector 6 when the deceleration fuel cut-off condition is satisfied during the running of the automobile. The engine control unit 112 determines that the deceleration fuel cut condition is satisfied based on the detection signal of the accelerator opening sensor SW 12.

The engine 1 performs the fuel cut operation after the fuel supply is stopped. The ignition plug 25 does not ignite during the fuel cut operation. The intake electric motor S-VT 23 sets the valve timing of the intake valve 21 to a preset target valve timing. The target valve timing is a valve timing suitable for recovery from fuel cut. After stopping the supply of fuel to the engine 1, the engine control section 112 sets the valve timing of the intake valve 21 to the target valve timing by the intake motor S-VT 23.

The diagnosis unit 111 diagnoses a failure of the cylinder pressure sensor SW6 when a certain condition is satisfied.

Specifically, the diagnosing unit 111 diagnoses a failure of the cylinder pressure sensor SW6 while the engine 1 continues to operate stably for a certain period of time. During the steady operation of the engine 1, for example, the variations in the combustion pressure of the air-fuel mixture, the temperature of the wall surface of the combustion chamber, the specific heat ratio of the air-fuel mixture, and the like are small as compared with during the transient operation of the engine 1. When the in-cylinder environment is stable, if the failure diagnosis of the cylinder pressure sensor SW6 is performed, it is possible to suppress variation in the output of the cylinder pressure sensor SW6 that is not related to the failure.

The diagnostic unit 111 is not limited to performing the diagnosis during the steady operation of the engine 1, and diagnoses a failure of the cylinder pressure sensor SW6 during the fuel cut operation of the engine 1. The diagnosing unit 111 can thus diagnose a failure of the cylinder pressure sensor SW6 based on a pressure change in the combustion chamber 17 that is not affected by combustion of the air-fuel mixture. It is also advantageous that, during the fuel cut operation of the engine 1, the ignition plug 25 is not ignited, so that the detection signal of the cylinder pressure sensor SW6 is not affected by the noise of the ignition plug 25.

Main structure of the functional module

The diagnostic unit 111 mainly includes an operating state determination unit 1111 for determining a steady operation, a fuel cut operation, and the like, an estimation unit 1114 for estimating a cylinder pressure at a time point (+ α ° CA) after the maximum point of a specific crank angle with respect to the compression top dead center, a reading unit 1113 for reading a detection signal of the cylinder pressure sensor SW6 at the time point after the maximum point, and a failure determination unit 1112 for determining a failure of the cylinder pressure sensor SW6 by receiving signals output from the estimation unit 1114 and the reading unit 1113.

The operating state determination unit 1111 determines that the engine 1 continues to operate stably for a predetermined period. Here, the operating state determining unit 1111 determines that the engine 1 is operating stably when the operating state of the engine 1 is kept constant or substantially constant. Specifically, the operating state determining unit 1111 determines that the engine 1 is operating stably when at least one of the amount of air filled in the combustion chamber 17, the amount of EGR gas contained in the air-fuel mixture in the combustion chamber 17, and the amount of fuel supplied to the combustion chamber 17 falls within a certain range.

More specifically, the operating condition determining unit 1111 determines the amount of air filled in the combustion chamber 17, the amount of EGR gas contained in the air-fuel mixture in the combustion chamber 17, and the amount of fuel supplied to the combustion chamber 17, based on the detection signals of the sensors SW1 to SW 17. When the operating state determining unit 1111 determines that the amount of change of each of the 3 amounts is equal to or less than a predetermined value, it determines that the engine 1 is operating stably.

Then, when the engine 1 continues the steady operation until the set time (several seconds in this configuration example) elapses, the operation state determination unit 1111 determines that "the engine 1 continues the steady operation for a certain period".

When it is determined that the deceleration fuel cut condition is satisfied in the engine control unit 112, the operation state determination unit 1111 determines that "the engine 1 starts the fuel cut operation".

When the operating condition determining unit 1111 determines the steady operation to be continued or when the operating condition determining unit 1111 determines the fuel cut operation to be performed, the estimating unit 1114 estimates the cylinder pressure at the time point after the highest point based on the operating condition of the engine 1. The cylinder pressure value estimated by the estimation unit 1114 is hereinafter referred to as "predicted value after maximum point". The post-peak predicted value is a value of cylinder pressure that the cylinder pressure sensor SW6 should reach if there is no failure.

The predicted value after the highest point estimated by the estimation unit 1114 is input to the failure determination unit 1112. The most recent point in time is an example of "1 st point in time".

The reading section 1113 reads the detected signal value of the cylinder pressure sensor SW6 at the post-highest point in time (i.e., post-highest point signal value) and the detected signal value of the cylinder pressure sensor SW6 at the pre-highest point in time (- α ° CA) that is advanced by the same specific crank angle as the post-highest point in time with respect to the compression top dead center, the pre-highest point in time being an example of "time 2".

In addition, a specific crank angle is set so that the time point after the highest point is the earlier stage of the power stroke. The "early stage" herein may refer to, for example, an early stage when the power stroke is divided into early, middle and late stages. The specific crank angle may be set to, for example, about 60 ° CA. The influence of the cooling loss can be suppressed by setting the time point after the highest point to the early stage of the power stroke. Therefore, the accuracy of the fault diagnosis can be improved.

In addition, the specific crank angle may be reset in real time in accordance with the operating state of the engine 1. At this time, the specific crank angle is set not at the transition timing at which the intake valve 21 is closed by the intake electric motor S-VT 23 but after the closing of the intake valve 21 is completed. Further, the specific crank angle may be set to be before the ignition timing in each cycle. By setting in this way, the influence of the closing operation of the intake valve 21 and the influence of combustion of the air-fuel mixture can be suppressed. Therefore, the accuracy of the fault diagnosis can be improved.

That is, in order to improve the accuracy of the failure diagnosis of the cylinder pressure sensor SW6, it is preferable that the time before the highest point is set to the ignition timing, the specific crank angle is set so that the time after the highest point is set to the early stage of the power stroke, and the setting is performed after the closing timing IVC of the intake valve 21.

The signal value before the highest point read by the reading section 1113 is input to the estimating section 1114. The estimation unit 1114 estimates a predicted value after the highest point based on the input signal value before the highest point. On the other hand, the post-peak signal value read by the reading unit 1113 is input to the failure determination unit 1112.

The failure determination unit 1112 determines a failure of the cylinder pressure sensor SW6 based on a decrease in the output of the detection signal of the cylinder pressure sensor SW 6. As described later, the cause of the decrease in the output of the detection signal of the cylinder pressure sensor SW6 is an insulation abnormality of the insulating portion 712 of the cylinder pressure sensor SW 6. The failure determination unit 1112 determines that the cylinder pressure sensor SW6 has failed based on a comparison between the predicted value after the highest point estimated by the estimation unit 1114 and the signal value after the highest point read by the reading unit 1113. The comparison is made indirectly by a threshold based on the post-peak prediction value and a difference based on the post-peak signal value.

More specifically, the failure determination unit 1112 determines that the cylinder pressure sensor SW6 has failed when the magnitude of the difference between the post-peak signal value and the pre-peak signal value exceeds a threshold value set in accordance with the post-peak predicted value. Failure determination unit 1112 is an example of a "determination unit".

The diagnostic unit 111 further includes a threshold setting unit 1115. The threshold setting unit 1115 sets a threshold based on the predicted value after the highest point. Failure determining unit 1112 reads the threshold set by threshold setting unit 1115.

The failure determination unit 1112 determines that the cylinder pressure sensor SW6 has failed, and notifies it to the notification unit 57. The failure of the cylinder pressure sensor SW6 is notified to the user.

-fault determination limiting the relevant functional module

The diagnostic unit 111 includes a limiting unit 1117 for limiting the failure determination by the failure determination unit 1112, a delay determination unit 1118 for outputting a signal to the limiting unit 1117, and a valve timing determination unit 1119 as functional blocks related to failure determination limitation.

The restriction portion 1117 restricts the failure diagnosis of the cylinder pressure sensor SW6 until the valve timing of the intake valve 21 becomes the target valve timing when the engine 1 continues the steady operation or the fuel cut operation is performed. The cylinder pressure sensor SW6 outputs a signal corresponding to a pressure change due to a volume change of the combustion chamber 17 or the like. The failure determination unit 1112 performs failure determination based on the detection signal of the cylinder pressure sensor SW6 corresponding to the pressure change as described above. When the closing timing of the intake valve 21 is changed, the time point at which the gas compression in the combustion chamber 17 starts changes, and therefore the pressure in the combustion chamber 17 and the maximum pressure in the compression stroke change. Thus, even if the cylinder pressure sensor SW6 is not malfunctioning, the output of the cylinder pressure sensor SW6 is uneven, and the accuracy of the failure diagnosis of the cylinder pressure sensor SW6 is deteriorated. By restricting the failure diagnosis of the cylinder pressure sensor SW6 until the closing timing of the intake valve 21 becomes the target timing, the failure determination unit 1112 can perform the failure determination of the cylinder pressure sensor SW6 when the intake valve 21 is at the specific closing timing. This can improve the accuracy of the failure diagnosis of the cylinder pressure sensor SW 6.

The detection signal of the intake cam position sensor SW13 is input to the valve timing determination portion 1119. The valve timing determination portion 1119 outputs a signal to the restriction portion 1117 upon determining that the valve timing of the intake valve 21 has reached the target valve timing based on the detection signal of the intake cam position sensor SW 13.

Further, when the fuel cut operation is performed, the restriction unit 1117 restricts the failure determination unit 1112 to perform the failure determination of the cylinder pressure sensor SW6 until a set time elapses from the stop of the fuel supply to the engine 1. The environment in the combustion chamber 17 is unstable in a period immediately after the fuel supply to the engine 1 is stopped. For example, in a period immediately after the fuel supply to the engine 1 is stopped, sometimes the EGR gas remaining in the EGR passage 52 enters the combustion chamber 17 and thus the specific heat ratio of the gas in the combustion chamber 17 cannot be kept fixed. In addition, in a period immediately after the fuel supply to the engine 1 is stopped, the temperature variation of the wall surface in the combustion chamber 17 may be large. Therefore, even if the cylinder pressure sensor SW6 is not malfunctioning, the output of the cylinder pressure sensor SW6 is uneven, and the accuracy of the failure diagnosis of the cylinder pressure sensor SW6 is lowered.

Therefore, the limiting unit 1117 limits the failure determination of the cylinder pressure sensor SW6 by the failure determining unit 1112 until the set time elapses from the stop of the fuel supply to the engine 1. Thus, the diagnosing unit 111 can more accurately diagnose the failure of the cylinder pressure sensor SW6 during the fuel cut operation.

The diagnosis unit 111 includes a delay determination unit 1118. The delay determination unit 1118 counts the number of cycles of the engine 1. The delay determination unit 1118 is a timer for measuring the set time. The delay determination unit 1118 starts counting the number of cycles after receiving a signal indicating that the engine 1 is running with fuel cut from the running state determination unit 1111. The delay determination unit 1118 determines that the set number of cycles has elapsed since the stop of the fuel supply to the engine 1, and outputs a signal to the restriction unit 1117. In addition, the delay determination unit 1118 may measure the time elapsed from the stop of the fuel supply to the engine 1 instead of counting the number of cycles.

(concrete constitution related to failure diagnosis)

Fig. 9 shows an example of the sensing signal output when the cylinder pressure sensor SW6 is normal and the sensing signal output when the cylinder pressure sensor SW6 fails. In fig. 9, the horizontal axis represents the crank angle, and 0 represents the compression top dead center. The vertical axis in fig. 9 represents the pressure (cylinder pressure) in the combustion chamber 17, and is proportional to the detection signal of the cylinder pressure sensor SW 6.

As shown in fig. 9, the cylinder pressure sensor SW6 is normal, the cylinder pressure is maximum near the compression top dead center, and is substantially symmetrical about the crank angle corresponding to the point where the pressure is maximum. When the cylinder pressure sensor SW6 has no failure (normal state), the post-peak signal value is slightly lower than the pre-peak signal value due to the influence of cooling loss or the like.

Fig. 10 is an example of the pressure difference at the normal time. The pressure difference shown in FIG. 10 is a difference obtained by subtracting the post-peak signal value (≈ post-peak predicted value) in normal time from the pre-peak signal value.

As shown in fig. 10, when the rotation number of the engine 1 is increased, the cooling loss per unit time is reduced, and therefore the cylinder pressure after compression top dead center is substantially increased. This generally reduces the pressure difference during normal operation.

As shown in fig. 10, when the amount of air filled in the combustion chamber 17 (the amount of air in the cylinder) is large, the leakage in the compression stroke is large, and the cylinder pressure after compression top dead center is substantially reduced. This generally reduces the pressure difference during normal operation.

The tendency shown in fig. 10 is a tendency when the cylinder pressure sensor SW6 operates normally. In contrast, the inventors of the present application have made studies and have newly found a tendency of the cylinder pressure sensor SW6 to fail.

Specifically, when a failure of the cylinder pressure sensor SW6 due to the influence of heat or the like is newly found, the post-peak signal value is greatly increased or decreased compared with the pre-peak signal value. Therefore, if the cylinder pressure sensor SW6 fails, the actually detected post-peak signal value relatively greatly deviates from the post-peak predicted value that would be expected to be reached at normal times. After the present inventors have discussed, it is found that when the insulation portion 712 is abnormal, the signal value decreases after the highest point. At this time, if the symmetry of the signal value of the cylinder pressure sensor SW6 is broken, the difference between the signal value before the highest point and the predicted value after the highest point and the signal value after the highest point becomes large.

Then, as described above, the diagnosis unit 111 determines that the cylinder pressure sensor SW6 is malfunctioning based on the comparison between the predicted value after the highest point estimated in advance and the signal value after the highest point read by the reading unit 1113.

It is possible to suppress the output variation unrelated to the failure of the cylinder pressure sensor SW6 if it is during the continuous steady operation of the engine 1. Therefore, while suppressing the output variation that is not related to the failure, the diagnosis can be performed at the time point when the output significantly increases or decreases at the time of the failure. This enables more accurate diagnosis of the failure of the insulating portion 712.

As described above, the estimated value after the highest point is estimated by the estimation unit 1114. The estimating unit 1114 estimates a predicted value after the highest point based on the signal value before the highest point. The memory 102 of the ECU10 stores a map corresponding to the pressure difference shown in fig. 10. The estimation unit 1114 reads the pressure difference based on the operating state of the engine 1 based on the map, and subtracts the pressure difference from the before-highest-point signal value to estimate a predicted value after the highest point.

As is clear from the above estimation technique, the predicted value after the highest point coincides with the signal value after the highest point when the cylinder pressure sensor SW6 is operating normally. Therefore, the difference between the post-peak predicted value and the pre-peak signal value shows the tendency of the example of fig. 10.

That is, when the engine 1 speed is high, the estimated value after the highest point estimated by the estimation unit 1114 is substantially higher than when the engine 1 speed is low. Thus, the influence of the cooling loss has been considered. The influence of the cooling loss is not related to the failure of the cylinder pressure sensor SW6, but may be an error factor when estimating the cylinder pressure. To more accurately perform the fault diagnosis, an effective method is to consider the influence of the cooling loss.

When the amount of air filled in the combustion chamber 17 is large, the estimated value after the highest point estimated by the estimation unit 1114 is substantially lower than when it is small. Thus, leakage at the joint of the piston ring has been taken into account. This phenomenon is not related to the failure of the cylinder pressure sensor SW6, but may be an error factor when estimating the cylinder pressure. To make the fault diagnosis more accurate, an effective method is to consider leakage from the junction.

Further, as a tendency peculiar to the time when the air-fuel mixture is burned in the combustion chamber 17 (when the engine 1 continues the steady operation), the pressure in the combustion chamber 17 estimated by the estimating unit 1114 is larger when the load of the engine 1 is high than when it is low.

The engine 1 has a higher combustion pressure when the load is high than when the load is low. The inventors of the present application have confirmed that, at the time of high combustion pressure, the signal value of the cylinder pressure sensor SW6 appears on the low output side due to the increased engagement of the diaphragm 71 and the piezoelectric device 75. This phenomenon causes the post-peak signal value to drop significantly compared to the pre-peak signal value. These tendencies, although not related to the failure of the cylinder pressure sensor SW6, may become error factors in estimating the cylinder pressure. To more accurately perform the fault diagnosis, an effective method is to consider the influence of the engagement.

Specifically, when the load on the engine 1 is high, the estimated value after the highest point estimated by the estimation unit 1114 is lower than that when the load is low. This is advantageous in more accurately diagnosing a failure of the cylinder pressure sensor SW 6.

For example, when the air-fuel ratio is fixed, the load on the engine 1 increases as the amount of air filled in the combustion chamber 17 increases. Therefore, as shown in fig. 11, the pressure difference used for estimation of the predicted value after the highest point shows the same tendency as or a similar tendency to the in-cylinder air amount.

For example, when the EGR gas amount is large, the specific heat ratio of the air-fuel mixture and the combustion temperature are smaller than when the EGR gas amount is small. At this time, the influence of combustion on the cylinder pressure sensor SW6 is relatively small, and the normal pressure difference is considered to be small (see fig. 12). These tendencies, although not related to the failure of the cylinder pressure sensor SW6, may become error factors in estimating the cylinder pressure. Therefore, to improve the accuracy of the failure diagnosis, an effective method is to consider the EGR gas amount.

Specifically, when the amount of EGR gas contained in the air-fuel mixture is large, the estimated value after the highest point estimated by the estimation unit 1114 is higher than when the amount is low. This is advantageous in more accurately diagnosing a failure of the cylinder pressure sensor SW 6.

The diagnosis unit 111 sets a threshold value corresponding to the predicted value after the highest point. Specifically, the threshold value setting unit 1115 sets the threshold value so that the threshold value is larger than a difference (i.e., a normal pressure difference) obtained by subtracting the predicted value after the highest point from the signal value before the highest point. The threshold value is set larger when the predicted value is lower after the highest point than when it is high.

In the case of the above-described configuration, the diagnostic unit 111 reduces the threshold value when the engine speed is high, for example, as compared with when the engine speed is low. Similarly, for example, when the amount of air filled in the combustion chamber 17 is large, the diagnostic unit 111 increases the threshold value compared to when it is small. Thus, the threshold value can be set to be equal to or greater than the pressure difference due to the cooling loss, or to be equal to or greater than the increase value due to the leakage loss. This improves the accuracy of the failure diagnosis.

The failure determination unit 1112 indirectly compares the post-peak prediction value and the post-peak signal value. Specifically, the failure determination unit 1112 compares a threshold value set in accordance with the predicted value after the highest point with the difference between the signal value before the highest point and the signal value after the highest point, and determines that the cylinder pressure sensor SW6 has failed when the magnitude of the difference obtained by the comparison exceeds the threshold value. Thus, the failure diagnosis of the cylinder pressure sensor SW6 can be performed more accurately.

In addition, it can be designed that: the failure determination unit 1112 repeatedly performs comparison between the difference between the pre-peak signal value and the post-peak signal value and the threshold value, and determines that the cylinder pressure sensor SW6 has failed when the magnitude of the difference obtained by performing the comparison a plurality of times in succession exceeds the threshold value.

For example, a change in the engagement between the components constituting the cylinder pressure sensor SW6 during the compression stroke may cause a pressure drop in the combustion chamber 17 after compression top dead center. As described above, although the pressure drop is a temporary phenomenon, it may cause an erroneous diagnosis of the cylinder pressure sensor SW.

In fact, when the cylinder pressure sensor SW6 fails, the pressure in the combustion chamber 17 continues to decrease, and therefore, as described above, the determination by the failure determination unit 1112 is repeated, which is advantageous in more accurately diagnosing the failure of the cylinder pressure sensor SW 6.

(failure diagnosis step of Cylinder pressure sensor)

Fig. 13A and 13B are flowcharts of the fault diagnosis step of the cylinder pressure sensor SW6 performed by the fault diagnosis apparatus 100. In step S1 after the start, the failure diagnosis device 100 reads the detection signals of the sensors SW1 to SW 17.

In the next step S2, the operating condition determining unit 1111 determines whether or not the engine 1 continues to operate stably for a predetermined period of time, based on the detection signals of the sensors SW1 to SW 17. Specifically, the operation state determination unit 1111 determines that the engine 1 is operating stably when all of the amounts of change in the amount of air filled in the combustion chamber 17, the amount of EGR gas contained in the air-fuel mixture in the combustion chamber 17, and the amount of fuel supplied to the combustion chamber 17 are determined to be equal to or less than a certain value. For example, the amount of fuel supplied to the combustion chamber 17 can be determined by a detection signal of the accelerator opening sensor SW 12.

If it is determined in step S2 that the steady operation is continued, the process flow proceeds to step S12. If it is determined that the steady operation has not been continued, the process flow proceeds to step S3. If the determination is made as to the closing timing of the intake valve 21 (step S12), the process proceeds to the process of performing the failure diagnosis of the cylinder pressure sensor SW6 (steps S13 to S24). If the determination is made as to whether or not the fuel cut operation is executed (steps S3 to S9), the process related to the failure diagnosis restriction is performed (steps S10 to S11), and the process proceeds to the process of executing the failure diagnosis (steps S13 to S24).

Specifically, in step S12, the valve timing determination part 1119 of the diagnosis part 111 determines whether or not the closing timing of the intake valve 21 is the target timing or almost the target timing. While the determination at step S12 is no, the process flow repeats step S12. While the process flow repeats step S12, the restriction unit 1117 restricts the failure determination unit 1112 from executing failure diagnosis. If yes in step S12, the process flow proceeds to step S13.

On the other hand, in step S3, the operation state determination unit 1111 determines whether or not the deceleration fuel cut condition is satisfied. Specifically, the operating state determining unit 1111 determines whether or not the accelerator opening is 0 based on the detection signal of the accelerator opening sensor SW 12. When the deceleration fuel-off condition is satisfied when the accelerator opening degree is 0, the process flow proceeds to step S4. And when the deceleration fuel-off condition is not met, the processing flow returns.

In step S4, the operating condition determining unit 1111 determines whether or not the engine water temperature exceeds a predetermined value based on the detection signal of the water temperature sensor SW 10. And if the water temperature of the engine exceeds a certain value, fuel cutoff is executed. If the engine water temperature does not exceed a certain value, fuel cut is not performed. When the determination of step S4 is yes, the process flow moves to step S5. If no in step S4, the process flow returns.

In step S5, the operation state determination unit 1111 determines whether or not the opening degree of the EGR valve 54 is 0 or substantially 0. The EGR valve 54 is closed during fuel cut. If yes in step S5, the process flow advances to step S6, and if no in step S5, the process flow returns.

In step S6, engine control unit 112 stops fuel supply to engine 1 by injector 6 (i.e., cuts off fuel). In the next step S7, the engine control unit 112 sets the valve timing of the intake valve 21 to the target valve timing set in the fuel cut operation by the intake motor S-VT 23.

In step S8, the operation state determination unit 1111 determines whether or not the deceleration fuel cut stop condition is satisfied. For example, when the engine speed is excessively reduced, the engine control unit 112 stops fuel cut. If the accelerator opening exceeds 0, fuel cut is stopped. If yes in step S8, the process flow proceeds to step S9, and engine control unit 112 suspends deceleration and fuel cut. When no is determined in step S8, the process flow advances to step S10.

In step S10, the valve timing determination part 1119 of the diagnosis part 111 determines whether the closing timing of the intake valve 21 is the target timing or almost the target timing. While the determination at step S10 is no, the process flow repeats step S10. While the process flow repeats step S10, the restriction unit 1117 restricts the failure determination unit 1112 from executing failure diagnosis. If the step S10 determines yes, the process flow moves to step S11.

In step S11, delay determination unit 1118 of diagnosis unit 111 determines whether or not the delay period has elapsed since the start of fuel cut. Here, the upper graph 141 in fig. 14 shows the relationship between the engine revolution number and the delay period. The delay period is fixed regardless of the number of engine revolutions. After a certain number of cycles, each combustion chamber 17 can be subjected to at least one gas exchange, and the environment in each combustion chamber 17 becomes stable.

As described above, the delay determination unit 1118 may measure a time instead of counting the number of cycles of the engine 1. The lower graph 142 of fig. 14 is an example of the relationship between the number of engine revolutions and the delay time. The delay time is shorter as the number of engine revolutions is higher. Since the time required for 1 cycle is shorter as the engine revolution number is higher.

Returning to the flow of fig. 13A, when no is determined in step S11, the process flow repeats step S11. The limiting unit 1117 limits the execution of the failure diagnosis by the failure determining unit 1112. If the determination at step S10 is yes, the process flow advances to step S13.

The limiting portion 1117 limits the failure diagnosis of the cylinder pressure sensor SW6 until two conditions are satisfied, that is, until the closing timing of the intake valve 21 becomes the target timing and a delay period (or delay time) elapses from the fuel cut. In this way, the failure determination unit 1112 can perform the failure diagnosis of the cylinder pressure sensor SW6 when the combustion chamber 17 is in the same state, and therefore the accuracy of the failure diagnosis can be improved.

The processing flow of step S13 and thereafter shown in the flow of fig. 13B is common when the engine 1 continues to operate stably and when a delay period has elapsed since the fuel cut.

Specifically, in step S13, the diagnostic portion 111 sets a specific crank angle based on the closing timing of the intake valve 21 and the ignition timing of the ignition plug 25. In this configuration example, the diagnosis unit 111 sets the specific crank angle such that the post-peak time point is the early stage of the power stroke and the pre-peak time point is the pre-ignition timing.

Next, in step S14, the reading unit 1113 of the diagnostic unit 111 reads the detection signal of the cylinder pressure sensor SW 6. Specifically, the reading section 1113 sets the pre-peak time point based on the specific crank angle set at step S13, and reads the pre-peak signal value corresponding to the setting.

Next, in step S15, the estimation unit 1114 of the diagnosis unit 111 estimates, based on the before-highest-point signal value, a post-highest-point signal value (post-highest-point predicted value) that is estimated to be achieved if the cylinder pressure sensor SW6 has no failure. Next, in step S16 following step S15, the threshold setting unit 1115 of the diagnosis unit 111 sets a threshold corresponding to the predicted value after the highest point.

Then, in step S17, the reading unit 1113 of the diagnostic unit 111 reads the detection signal of the cylinder pressure sensor SW6 again. Specifically, the reading section 1113 sets the post-peak time point based on the specific crank angle set in step S13, and reads the post-peak signal value corresponding to the setting.

Then, in step S18, the failure determination unit 1112 of the diagnosis unit 111 compares the post-peak predicted value with the post-peak signal value. Specifically, the failure determination unit 1112 compares a threshold value set based on the predicted value after the highest point with a difference obtained by subtracting the signal value after the highest point from the signal value before the highest point.

In step S19, failure determination unit 1112 determines whether or not the difference between the pre-peak signal value and the post-peak signal value exceeds a threshold value based on the post-peak prediction value. When the threshold value is exceeded, the cylinder pressure sensor SW6 is considered to be malfunctioning, and the process flow advances to step S20. In step S20, the failure determination unit 1112 adds 1 to the failure determination count. If the threshold value is not exceeded, the cylinder pressure sensor SW6 is considered to be not malfunctioning, and the process flow advances to step S21. In step S21, the failure determination unit 1112 sets the failure determination count to 0.

Then, in step S22, the failure determination unit 1112 determines whether or not the failure determination count exceeds a predetermined value. For example, the predetermined value may be about 3 to 5. If no, step S22 returns the process flow. The yes judgment in step S22 the process flow advances to step S23. That is, when the failure determination unit 1112 determines that the cylinder pressure sensor SW6 is failed several times in succession, the failure determination unit 1112 diagnoses that the cylinder pressure sensor SW6 is failed in step S23. The failure of the cylinder pressure sensor SW6 is diagnosed based on several determinations, whereby erroneous diagnosis can be prevented.

Next, in step S24 of step S23, failure determination unit 1112 executes notification by notification unit 57. The user is notified that the cylinder pressure sensor SW6 is malfunctioning. Thereby replacing the failed cylinder pressure sensor SW6, or the like.

(time chart)

Fig. 15 and 16 are example timing charts of changes in the respective parameters when the failure diagnosis device 100 of the cylinder pressure sensor SW6 performs failure diagnosis of the cylinder pressure sensor SW6 in accordance with the flowcharts of fig. 13A and 13B. The horizontal axis of fig. 15 and 16 represents the passage of time.

Here, fig. 15 is a time chart when the failure diagnosis is performed while the engine 1 is continuously and stably operating, and fig. 16 is a time chart when the failure diagnosis is performed while the fuel cut operation is performed.

Failure diagnosis during continuous stable operation

First, when the driver resets the accelerator pedal opening that has been depressed while the vehicle is traveling, the accelerator opening gradually decreases, and the accelerator opening is substantially constant at time t1 (see waveform 151). Thereby, the amount of fuel supplied into the combustion chamber 17 is also substantially fixed. Thus, the amount of change in the fuel is determined to be equal to or less than a certain value.

The opening degree of the EGR valve 54 is gradually decreased together with the accelerator opening degree, and the opening degree of the EGR valve 54 is also substantially constant at time t1 (see waveform 152). Accordingly, the amount of EGR gas contained in the air-fuel mixture formed in the combustion chamber 17 is also substantially constant. Thus, it is determined that the amount of change in the EGR gas is equal to or less than a certain value.

Although not shown in fig. 15, in the time chart illustrated here, the amount of air charged in the combustion chamber 17 is also substantially constant at time t 1. Thus, it is determined that the amount of change in the air filled in the combustion chamber 17 is equal to or less than the fixed value at time t 1.

By the determination as above, the ECU10 determines that the engine 1 is operating stably. As shown by the waveform 153, the steady operation flag indicating the steady operation of the engine 1 changes from 0 to 1 at time t 1. When the steady operation flag becomes 1, the operation state determination unit 1111 calculates the elapsed time after the steady operation flag becomes 1 from 0 (see the waveform 155). The calculation may be performed by directly measuring the time or indirectly light through the number of cycles.

At this time, the closing timing of the intake valve 21 becomes the target timing corresponding to the steady operation. The time required for the closing timing of the intake valve 21 to become the target timing also changes depending on the phase difference between the closing timing before the change and the target timing.

As shown by a waveform 155, the operating state determining unit 1111 determines that the engine 1 continues the steady operation for a certain set time at time t 2. After that, the operating state determining portion 1111 determines at time t3 that the valve timing of the intake valve 21 has reached the target timing. As described above, when the two conditions of the steady operation being continued and the valve timing of the intake valve 21 becoming the target valve timing are satisfied, the execution flag of the failure diagnosis changes from 0 to 1 at time t3 as shown by the waveform 156.

Since the execution flag of the failure diagnosis becomes 1, the failure determination unit 1112 starts the failure determination of the cylinder pressure sensor SW 6. Then, at time t4, when the driver depresses the accelerator pedal, and the engine 1 shifts from the steady operation to the transient operation, the steady operation flag changes from 1 to 0. At the same time, the failure diagnosis of the cylinder pressure sensor SW6 should be suspended, and the failure diagnosis execution flag also changes from 1 to 0. The calculation of the elapsed time is also reset.

Fault diagnosis during fuel cut operation

First, when the driver resets the depressed accelerator pedal while the vehicle is traveling, the accelerator opening degree gradually decreases, and the accelerator opening degree becomes 0 at time t1 (see waveform 161). The opening degree of the EGR valve 54 gradually decreases together with the accelerator opening degree, and the opening degree of the EGR valve 54 also becomes 0 at time t1 (see waveform 162). Although not shown in fig. 16, the water temperature of the engine 1 exceeds a predetermined value, and fuel can be cut off at a reduced speed. The F/C flag changes from 0 to 1 at time t1 as shown by waveform 163. The F/C flag becomes 1 and the engine control portion 112 stops the fuel supply. Therefore, after time t1, engine 1 is operated with fuel cut.

The closing timing of the intake valve 21 becomes a preset target timing. The time required for the closing timing of the intake valve 21 to become the target timing also changes depending on the phase difference between the closing timing before the change and the target timing. When the phase difference is large, as shown by the solid line in the waveform 164, the time required for the closing timing of the intake valve 21 to become the target timing is long. When the phase difference is small, as shown by the dashed-dotted line in the waveform 164, the time required for the closing timing of the intake valve 21 to become the target timing is short.

As shown by waveform 165, delay determination portion 1118 starts counting cycles after fuel cutoff starts. The delay period may be, for example, 7-9 cycles. The delay period has elapsed in the example of fig. 16 at time t 2.

The delay period is set here between the longest time (t 3-t 1) and the shortest time (t 3' -t 1) required for the closing timing of the intake valve 21 to become the target timing. The failure diagnosis of the cylinder pressure sensor SW6 is performed during the fuel cut operation of the engine 1. The failure diagnosis of the cylinder pressure sensor SW6 cannot be performed after the engine 1 finishes the fuel cut operation. If it is desired to increase the frequency of failure diagnosis of the cylinder pressure sensor SW6, it is desirable to perform failure diagnosis promptly after fuel supply to the engine 1 is stopped. Minimizing the delay period is advantageous for increasing the diagnostic frequency. Making the elapsed time of the delay period shorter than the longest change time required for the valve timing of the intake valve 21 to become the target timing is advantageous in increasing the frequency of failure diagnosis.

Making the elapsed time of the delay period longer than the shortest change time required for the valve timing of the intake valve 21 to become the target timing stabilizes the state in the combustion chamber 17, and is therefore advantageous for improving the accuracy of the failure diagnosis. By adjusting the delay period (or delay time), the accuracy of the failure diagnosis can be improved and the frequency of the failure diagnosis can be increased.

In the example of fig. 16, two conditions that the delay period has elapsed at time t3 and the valve timing of the intake valve 21 becomes the target valve timing are satisfied. The execution flag of the failure diagnosis changes from 0 to 1 at time t3 as shown by a waveform 166, and failure determination unit 1112 performs failure determination of cylinder pressure sensor SW 6.

In addition, in the example of fig. 16, when the timing at which the valve timing of the intake valve 21 becomes the target timing is early (is the timing t 3'), the execution flag of the failure diagnosis changes from 0 to 1 at the timing t2 as indicated by the chain-dashed line in the waveform 166.

Then, at time t4, the driver depresses the accelerator pedal, thereby causing the fuel cut to be suspended after the accelerator opening is larger than 0, so that the F/C flag becomes 0. At the same time, the failure diagnosis of the cylinder pressure sensor SW6 is also stopped, and therefore the failure diagnosis execution flag also becomes 0.

Other embodiments

Variation of the diagnostic method

In the above embodiment, the diagnosis unit 111 sets the threshold value based on the predicted value after the highest point, but is not limited to this configuration. The threshold value may be directly set based on the pre-peak signal value and the operating state of the engine 1, without intervening the post-peak prediction value. In this case, the threshold value tends to be the same as the pressure difference shown in fig. 10 to 12.

Variation of the procedure

Fig. 17 is a modification of the flow of the cylinder pressure sensor failure diagnosis. Steps S20 to S26 in fig. 17 replace steps S20 to S24 in fig. 13B.

First, in step S19, when failure determination unit 1112 determines that the difference between the pre-peak signal value and the post-peak signal value exceeds the threshold value based on the post-peak predicted value, the process flow proceeds to step S20, and when it determines that the difference is equal to or less than the threshold value, the process flow proceeds to step S21.

When proceeding to step S20, the failure determination unit 1112 determines that the cylinder pressure sensor SW6 has failed, and therefore increments the failure determination count by 1 and decrements the normal determination count by 1. On the other hand, in step S21, since it is considered that there is no failure in the cylinder pressure sensor SW6, the failure determination unit 1112 decrements the failure determination count by 1 and increments the normal determination count by 1.

In next step S22, failure determination unit 1112 determines whether or not the failure determination count exceeds a predetermined value. When yes is determined in step S22, the process flow advances to step S23. That is, since the frequency with which cylinder pressure sensor SW6 is determined to be faulty is higher than the frequency with which cylinder pressure sensor SW6 is determined not to be faulty, fault determination unit 1112 diagnoses that cylinder pressure sensor SW6 is faulty, and fault determination unit 1112 reports this to notification unit 57 in subsequent step S24.

On the other hand, when no is determined in step S22, the process flow advances to step S25. In step S25, the failure determination unit 1112 determines whether or not the normality determination count exceeds a predetermined value. The yes judgment in step S25 the process flow advances to step S26. Since the frequency with which the cylinder pressure sensor SW6 is determined not to have a failure is higher than the frequency with which the cylinder pressure sensor SW6 is determined to have a failure, the failure determination unit 1112 diagnoses that the cylinder pressure sensor SW6 has no failure and sets the failure determination count to 0. In addition, failure determination unit 1112 also sets the normality determination count to 0. When the determination at step S25 is no, the process flow returns.

As described above, the failure diagnosis apparatus 100 can prevent an erroneous diagnosis by diagnosing a failure of the cylinder pressure sensor SW6 using both the normal determination count and the failure determination count.

Instead of this, the operation state determination unit 1111 may determine the amount of change per unit time of each of the amount of air filled in the combustion chamber 17, the amount of EGR gas contained in the air-fuel mixture in the combustion chamber 17, and the amount of fuel supplied to the combustion chamber 17. In this case, when all of the 3 variations are determined to be equal to or less than a certain value, it can be determined that the engine 1 is operating stably.

In addition, the technique disclosed herein is not limited to the engine 1 of the above configuration. The engine 1 may take various configurations.

Description of the numbering

1 Engine

100 failure diagnosis device

1111 operating state determination unit

1112 failure determination unit (determination unit)

1113 reading section

1114, and an estimation unit

17 combustion chamber

25 sparking plug (ignition part)

71 diaphragm

75 piezoelectric device

SW1 air flow sensor (detecting part)

SW2 the 1 st inlet temperature sensor (detecting part)

SW3 pressure sensor 1 (detecting part)

SW4 No. 2 intake air temperature sensor (detecting part)

SW5 air inlet pressure sensor (detecting part)

SW6 cylinder pressure sensor (detecting part)

SW7 exhaust gas temperature sensor (detecting part)

SW8 Linear oxygen (Linear O)₂) Sensor (detecting part)

SW9 oxygen (Lambdao 2) sensor (detecting part)

SW10 water temperature sensor (detecting part)

SW11 crank angle sensor (detecting part)

SW12 accelerator opening sensor (detecting part)

SW13 air inlet cam position sensor (detecting part)

SW14 exhaust cam position sensor (detecting part)

SW15EGR differential pressure sensor (detecting part)

SW16 combustion pressure sensor (detecting part)

SW17 No. 3 intake air temperature sensor (detecting part)