阅读说明：本技术 内燃机的异常判定装置 (Abnormality determination device for internal combustion engine ) 是由 关口畅 木本隆史 藤井正博 于 2020-01-17 设计创作，主要内容包括：提供内燃机的异常判定装置。利用通气管道将增压器的上游侧的进气通路与曲轴箱相连接的内燃机的异常判定装置具备：进气流量传感器,检测进气通路的进气流量；压力传感器,检测通气管道的压力；和异常判定单元,判定通气管道的异常。异常判定单元将与进气流量相应的压力跟与进气流量相应的阈值相比较,累计压力为阈值以上的次数,在其累计值在规定时间内为规定值以上时判定为通气管道异常,因此能在短时间内高精度地判定通气管道的异常。异常判定单元计算出与进气流量相应的权重系数,利用权重系数对压力为阈值以上的次数赋予权重,因此能增大进气流量增加而判定精度提高的内燃机11的高负荷时的累计值,能在更短时间内得到更高精度的判定结果。(Provided is an abnormality determination device for an internal combustion engine. An abnormality determination device for an internal combustion engine, which connects an intake passage on the upstream side of a supercharger with a crankcase by means of a breather pipe, is provided with: an intake flow sensor that detects an intake flow rate of the intake passage; a pressure sensor that detects a pressure of the ventilation duct; and an abnormality determination unit that determines an abnormality of the ventilation duct. The abnormality determination means compares the pressure corresponding to the intake air flow rate with a threshold corresponding to the intake air flow rate, counts the number of times that the integrated pressure is equal to or greater than the threshold, and determines that the ventilation duct is abnormal when the integrated value is equal to or greater than a predetermined value within a predetermined time. The abnormality determination means calculates a weight coefficient corresponding to the intake air flow rate, and weights the number of times the pressure is equal to or greater than the threshold value using the weight coefficient, so that the integrated value at the time of high load of the internal combustion engine 11 in which the determination accuracy is improved by increasing the intake air flow rate can be increased, and a more accurate determination result can be obtained in a shorter time.)

1. An abnormality determination device of an internal combustion engine that connects a crankcase (19) and an intake passage (12) located on an upstream side of a supercharger (17) to each other with a breather passage (20), characterized in that,

the abnormality determination device for an internal combustion engine includes:

an intake flow rate sensor (16) that detects an intake flow rate of the intake passage (12);

a pressure sensor (29) that detects the pressure of the ventilation conduit (20); and

an abnormality determination unit (30) that determines an abnormality of the air duct (20),

the abnormality determination unit (30) compares the pressure of the ventilation duct (20) with a threshold value that is correlated with the value of the intake air flow rate detected when the pressure is detected, and the abnormality determination unit (30) integrates the number of times the pressure is equal to or greater than the threshold value to obtain an integrated value, and determines that an abnormality has occurred in the ventilation duct (20) when the integrated value is equal to or greater than a predetermined value within a predetermined time.

2. The abnormality determination device for an internal combustion engine according to claim 1,

the abnormality determination unit (30) calculates a weight coefficient (K) corresponding to the intake air flow rate, and weights the number of times the pressure is equal to or greater than the threshold value using the weight coefficient (K).

Technical Field

The present invention relates to an abnormality determination device for an internal combustion engine in which an intake passage on the upstream side of a supercharger is connected to a crankcase by a breather pipe.

Background

In such an abnormality determination device for an internal combustion engine, an abnormality determination device for an internal combustion engine is known from patent document 1 below, which calculates an integrated value of a predicted pressure of a breathing duct in a predetermined time period when the breathing duct is normal at a high load of the internal combustion engine when an intake air flow rate of an intake passage is equal to or greater than a predetermined flow rate and an integrated value of an actual pressure of the breathing duct detected by a pressure sensor in the predetermined time period, and determines that a connection portion of the breathing duct is detached when a ratio of the integrated value of the actual pressure to the integrated value of the predicted pressure is equal to or less than a threshold value.

Disclosure of Invention

Problems to be solved by the invention

However, according to the above-described conventional abnormality determination device for an internal combustion engine, since it is necessary to integrate the actual pressure and the predicted pressure of the breather pipe over a long period of time, it takes time to determine an abnormality, and if the correspondence relationship between the actual pressure and the predicted pressure varies due to a deviation in the output of the pressure sensor, the accuracy of the abnormality determination may be degraded.

The present invention has been made in view of the above circumstances, and an object thereof is to accurately determine an abnormality in a breather pipe of an internal combustion engine in a short time.

Means for solving the problems

In order to achieve the above object, according to the invention of claim 1, there is provided an abnormality determination device for an internal combustion engine in which a crankcase and an intake passage located upstream of a supercharger are connected to each other by a breather passage, the abnormality determination device comprising: an intake flow sensor that detects an intake flow rate of the intake passage; a pressure sensor that detects a pressure of the vent conduit; and an abnormality determination unit that determines an abnormality of the ventilation duct, the abnormality determination unit comparing a pressure of the ventilation duct with a threshold value that is correlated with a value of the intake air flow rate detected when the pressure is detected, the abnormality determination unit accumulating a number of times that the pressure is equal to or more than the threshold value to obtain an accumulated value, and determining that the ventilation duct has an abnormality when the accumulated value is equal to or more than a predetermined value within a predetermined time.

Further, in the invention according to claim 2, in the configuration of claim 1, the abnormality determination unit calculates a weight coefficient according to the intake air flow rate, and weights the number of times the pressure is equal to or greater than the threshold value using the weight coefficient.

The air flow meter 16 of the embodiment corresponds to the intake air flow sensor of the present invention.

Effects of the invention

According to the configuration of claim 1, the abnormality determination device for an internal combustion engine in which a crankcase and an intake passage located upstream of a supercharger are connected to each other by a breather passage includes: an intake flow rate sensor that detects an intake flow rate of the intake passage; a pressure sensor that detects a pressure of the ventilation duct; and an abnormality determination unit that determines an abnormality of the ventilation duct. The abnormality determination unit compares the pressure of the ventilation conduit with a threshold value that is related to the value of the intake air flow rate detected when the pressure is detected, and integrates the number of times the pressure is equal to or greater than the threshold value to obtain an integrated value, and determines that an abnormality has occurred in the ventilation conduit when the integrated value is equal to or greater than a predetermined value within a predetermined time.

Further, according to the configuration of claim 2, since the abnormality determination means calculates the weight coefficient corresponding to the intake air flow rate and weights the number of times the pressure becomes equal to or greater than the threshold value using the weight coefficient, it is possible to increase the integrated value of the internal combustion engine at a high load time, which is increased in the intake air flow rate and improved in the determination accuracy, obtain a more accurate determination result in a shorter time, and improve the determination accuracy without being affected by the deviation of the output of the pressure sensor.

Drawings

Fig. 1 is a diagram showing a configuration of an internal combustion engine provided with an abnormality determination device for a ventilation duct.

Fig. 2 is a block diagram of an abnormality determination device for a ventilation duct.

Fig. 3 is a graph showing a relationship among an intake air flow rate of an intake passage, a pressure of a ventilation pipe, and a weight coefficient.

Fig. 4 is an explanatory diagram illustrating the principle of abnormality determination of the ventilation duct.

Fig. 5 is a flowchart illustrating the operation of the ventilation duct abnormality determination device.

Description of the reference symbols

12: air intake passage

16: air flowmeter (Inlet flow sensor)

17: pressure booster

19: crankcase

20: air duct

29: pressure sensor

30: abnormality determination unit

K: weight coefficient

Detailed Description

Next, an embodiment of the present invention will be described with reference to fig. 1 to 5.

As shown in fig. 1, in an intake passage 12 of a four-stroke cycle internal combustion engine 11 mounted in a vehicle and having four cylinders connected in series, there are arranged in this order: an air cleaner 15 that removes dust from intake air from an intake port 13 at an upstream end in a flow direction of the intake air toward an intake manifold 14 at a downstream end in the flow direction of the intake air; an air flow meter 16 that measures an intake air flow rate; a supercharger 17 configured from a turbocharger or a supercharger that pressurizes intake air; and a throttle valve 18 that narrows the intake passage 12 to adjust the intake air flow rate. A position in the intake passage 12 sandwiched between the airflow meter 16 and the supercharger 17 is connected to a crankcase 19 of the internal combustion engine 11 through a breather pipe 20. Further, the intake manifold 14 and a crankcase 19 of the internal combustion engine 11 are connected by a Positive Crankcase Ventilation (PCV) pipe 21, and an intermediate portion of the PCV pipe 21 is opened/closed by a PCV valve 22.

Blow-by gas, which is formed by causing a portion of the fuel component contained in the intake air to flow from the combustion chamber of the internal combustion engine 11 into the crankcase 19 through the clearance between the piston and the cylinder, is returned to the intake passage 12 through the breather pipe 20, or is returned to the intake passage 12 through the PCV pipe 21, thereby preventing the fuel component contained in the blow-by gas from being discharged to the atmosphere.

That is, when the PCV valve 22 is opened during natural intake when the supercharger 17 is not operating, atmospheric pressure acts on the intake passage 12 on the upstream side of the throttle valve 18, whereas intake negative pressure of the internal combustion engine 11 acts on the intake passage 12 on the downstream side of the throttle valve 18, and therefore, intake air in the intake passage 12 on the upstream side of the throttle valve 18 flows into the crankcase 19 through the breather pipe 20, and from there, returns to the intake manifold 14 through the PCV pipe 21 together with blow-by gas, and is finally supplied to the combustion chamber of the internal combustion engine 11 together with the intake air.

Further, at the time of supercharging when the supercharger 17 is operated, the boost pressure acts on the intake passage 12 on the downstream side of the supercharger 17, but the boost pressure is prevented from moving to the crankcase 19 through the PCV pipe 21 by closing the PCV valve 22. Also, blow-by gas of the crankcase 19 is drawn out to the intake passage 12 by the negative pressure generated on the upstream side of the supercharger 17 in operation, and is supplied from there through the intake passage 12 into the combustion chamber of the internal combustion engine 11 together with intake air.

Further, when the first connection portion 23 of the breather pipe 20 connected to the intake passage 12 drops or the second connection portion 24 of the breather pipe 20 connected to the crankcase 19 drops during supercharging of the internal combustion engine 11, the blow-by gas flowing in the breather pipe 20 from the crankcase 19 toward the intake passage 12 may be released to the atmosphere, and therefore, it is necessary to detect an abnormality of the breather pipe 20 and issue an alarm. Therefore, the ventilation duct 20 is provided with a pressure sensor 29 that detects the pressure thereof.

As shown in fig. 2, an air flow meter 16, a pressure sensor 29, and an alarm unit 32 are connected to an abnormality determination unit 30 constituted by an electronic control unit that determines an abnormality of the air duct 20. The alarm unit 32 is constituted by, for example, a liquid crystal panel provided in the instrument panel.

Next, the procedure of the abnormality determination of the ventilation duct 20 by the abnormality determination unit 30 will be described with reference to the flowchart of fig. 5.

First, in step S1, the intake air flow rate of the intake passage 12 is detected by the airflow meter 16, and the pressure of the breather pipe 20 is detected by the pressure sensor 29. When the intake air flow rate is equal to or higher than the predetermined value and the internal combustion engine 11 is in the predetermined high load operation state in the next step S2, a map search is performed for the threshold value of the pressure according to the intake air flow rate in step S3.

The threshold value of the pressure is set as follows. In fig. 3 and 4, in a normal state where no leakage occurs in the breather pipe 20, when the pressure of the breather pipe 20 is detected for various intake air flow rates of the intake passage 12, the data thereof is concentrated in the range of the region a due to a detection error of the pressure sensor 29, and the like. The region a is shaped to be inclined downward to the right because, when the air duct 20 is normal, when the intake air flow rate increases, the pressure of the air duct 20 decreases due to the increase in intake negative pressure with the increase in intake air flow rate.

In addition, at the time of abnormality in which leakage occurs in the breather pipe 20, when the pressure of the breather pipe 20 is detected for various intake air flow rates of the intake passage 12, the data thereof is concentrated in the range of the region B due to a detection error of the pressure sensor 29 and the like. The region B is horizontal in shape because the pressure of the ventilation duct 20 communicating with the atmosphere hardly decreases even if the intake negative pressure increases due to an increase in the intake air flow rate when the ventilation duct 20 is abnormal.

The line L1 of the mapped threshold is set to pass through the middle between the line L2 of the lower limit of the region B and the line L3 of the upper limit of the region a. Therefore, when the pressure detected by the pressure sensor 29 is below the line L1 of the threshold value, it is estimated that the air duct 20 is temporarily normal, and when the pressure detected by the pressure sensor 29 is above the line L1 of the threshold value, it is estimated that the air duct 20 is temporarily abnormal.

Returning to the flowchart of fig. 5, when the pressure of the air duct 20 detected by the pressure sensor 29 is equal to or higher than the threshold value in step S4 and it is estimated that the air duct 20 is once abnormal, the weighting coefficient K is mapped and retrieved according to the intake air flow rate in step S5.

The mapping of the weight coefficient K is set as follows. As shown in fig. 3 and 4, the weight coefficient K is set in a high load region of the internal combustion engine 11 in which a line L1 of the threshold value of the pressure is set, and its value is set as follows: the distance α between the line L1 corresponding to the threshold value and the line L2 at the lower limit of the region B increases from 1. That is, the weight coefficient K increases from 1 in accordance with an increase in the intake air flow rate.

Returning to the flowchart of fig. 5, when the weight coefficient K is retrieved in the step S5, the weight coefficient K is accumulated in the weight addition determination counter in a step S6. The value added to the weight addition determination counter in this calculation cycle is 1 when the weight coefficient K is 1 because the intake air flow rate is small, but the value added to the weight addition determination counter in this calculation cycle is a value greater than 1 when the weight coefficient K is greater than 1 because the intake air flow rate is large.

Therefore, when the intake air flow rate is large and it is estimated that the ventilation duct 20 is temporarily abnormal, the integrated value of the weight addition determination counter is rapidly increased as compared with when the intake air flow rate is small. This is because the determination accuracy is improved as the pressure change corresponding to the change in the intake flow rate increases at a high load when the intake flow rate is large, and therefore the weighting coefficient K is set to be large and added to the weighting addition determination counter at a high load when the intake flow rate is large.

In the next step S7, 1 is added to the detection counter that is added in each operation cycle. If the pressure of the ventilation line 20 detected by the pressure sensor 29 in step S4 is less than the threshold value and it is estimated that the ventilation line 20 is temporarily normal, the steps S5 and S6 are skipped and the process proceeds to step S7.

If it is detected in the next step S8 that the number of calculation cycles necessary for highly accurate determination is equal to or greater than the predetermined value and the integrated value of the weight addition determination counter is smaller than the predetermined value in step S9, it is finally determined in step S10 that the air duct 20 is normal. On the other hand, if the integrated value of the weight addition determination counter is equal to or greater than the predetermined value in step S9, it is finally determined that the ventilation duct 20 is abnormal in step S11, and the alarm unit 32 is activated to issue an alarm to the occupant in step S12.

As described above, according to the present embodiment, the ventilation line 20 is finally determined to be abnormal if the proportion of the time estimated to be abnormal for the ventilation line 20 is equal to or greater than the predetermined value in the predetermined time detected by the detection counter, and the ventilation line 20 is finally determined to be normal if the proportion of the time estimated to be normal for the ventilation line 20 is equal to or greater than the predetermined value, so that the abnormality determination for the ventilation line 20 can be completed with high accuracy in a short time of 2 seconds to 10 seconds without being affected by the deviation of the output of the pressure sensor 29.

Further, since the weight coefficient K is set large and added to the weight addition determination counter at the time of a high load in which the determination accuracy is improved due to a large intake air flow rate, the abnormality determination can be completed with high accuracy in a shorter time.

The embodiments of the present invention have been described above, but various design changes can be made in the present invention without departing from the scope of the invention.

For example, the number of cylinders of the internal combustion engine 11 is not limited to four cylinders in the embodiment.

In the embodiment, the breather duct 20 is connected to the crankcase 19, but the operational effects of the invention according to the present application can be achieved even when the internal space of the crankcase 19 and the internal space of the cylinder head are communicated with each other and the breather duct 20 is connected to the cylinder head. Therefore, it is also included in the technical scope of the invention of the present application to connect the breather pipe 20 to other spaces communicating with the crankcase 19.