阅读说明：本技术 失火检测装置 (Fire detection device ) 是由 岸信之 友田明彦 山下明彦 新村竜太 于 2021-03-10 设计创作，主要内容包括：本发明提供一种失火检测装置。着眼于如下情况：没有基于离子的击穿辅助的期间中的承受压力与要求击穿电压之间的关系、即承受压力在失火时与燃烧时相比变低因此要求击穿电压变低,根据点火线圈的电压或电流来判定在没有击穿辅助的期间实施追加点火时的击穿的有无,对失火进行检测。在失火检测装置(100)中,通常点火正时计算部(101)计算通常点火正时。通常点火信号产生部(102)在通常点火正时产生通常点火信号(P1)。追加点火正时计算部(103)将刚进行通常点火之后的膨胀行程的规定正时计算为追加点火正时。追加点火信号产生部(104)在追加点火正时产生追加点火信号(P2)。击穿判定部(105)基于电压检测电路(40)的输出,对点火线圈(10)是否因追加点火而产生了击穿进行判定。(The invention provides a misfire detection apparatus. The following is noted: the relationship between the withstand pressure and the required breakdown voltage in the period in which the breakdown assistance by the ions is not provided, that is, the withstand pressure is lower in the case of misfire than in the case of combustion, so that the required breakdown voltage is lower. In a misfire detection device (100), a normal ignition timing calculation unit (101) calculates a normal ignition timing. A normal ignition signal generation unit (102) generates a normal ignition signal (P1) at a normal ignition timing. An additional ignition timing calculation unit (103) calculates a predetermined timing of an expansion stroke immediately after normal ignition as an additional ignition timing. An additional ignition signal generation unit (104) generates an additional ignition signal (P2) at an additional ignition timing. A breakdown determination unit (105) determines whether or not breakdown has occurred in the ignition coil (10) due to additional ignition, based on the output of the voltage detection circuit (40).)

1. A misfire detection device (100) for an internal combustion engine that normally ignites an ignition plug (50) in the vicinity of a compression top dead center of the internal combustion engine to burn a mixture gas, the misfire detection device comprising:

means (103, 104) for additionally igniting the spark plug (50) in an expansion stroke after normal ignition; and

means (105) for determining whether or not the spark plug has broken down due to additional ignition,

if it can be determined that the spark plug has broken down, the normal ignition is determined as misfire.

2. Misfire detection apparatus as recited in claim 1,

the spark plug (50) is connected to a secondary coil of an ignition coil (10) in which a primary coil and the secondary coil are magnetically coupled, and generates an induced voltage in the secondary coil by cutting off the current supply to the primary coil,

the means (105) for determining whether or not the breakdown has occurred determines whether or not the breakdown has occurred in the spark plug, based on a voltage generated in the primary coil during a predetermined determination period after additional ignition.

3. Misfire detection apparatus as recited in claim 2,

the predetermined determination period is a time period from a timing at which the voltage of the additional post-ignition primary coil after the normal-ignition normal combustion is substantially zero to a timing at which the voltage of the additional post-ignition primary coil after the normal-ignition misfire is substantially zero.

4. Misfire detection apparatus as recited in claim 1,

the spark plug (50) is connected to a secondary coil of an ignition coil (10) in which a primary coil and the secondary coil are magnetically coupled, and generates an induced voltage in the secondary coil by cutting off the current supply to the primary coil,

the means (105) for determining whether or not the breakdown has occurred determines whether or not the breakdown has occurred in the spark plug, based on a current flowing in the primary coil during a predetermined determination period after additional ignition.

5. Misfire detection apparatus as recited in claim 1,

the spark plug (50) is connected to a secondary coil of an ignition coil (10) in which a primary coil and the secondary coil are magnetically coupled, and generates an induced voltage in the secondary coil by cutting off the current supply to the primary coil,

the means (105) for determining whether or not the breakdown has occurred determines whether or not the breakdown has occurred in the spark plug, based on a voltage generated in the secondary side coil during a predetermined determination period after additional ignition.

6. Misfire detection apparatus as recited in claim 1,

the spark plug (50) is connected to a secondary coil of an ignition coil (10) in which a primary coil and the secondary coil are magnetically coupled, and generates an induced voltage in the secondary coil by cutting off the current supply to the primary coil,

the means (105) for determining whether or not the breakdown has occurred determines whether or not the spark plug has broken down, based on a current flowing in the secondary coil during a predetermined determination period after additional ignition.

Technical Field

The present invention relates to a misfire detection apparatus that detects a misfire of an engine, and more particularly, to a misfire detection apparatus that performs additional ignition in an expansion stroke immediately after normal ignition and detects a misfire based on whether or not a spark plug has punctured due to the additional ignition.

Background

In recent years, in view of improvement in repairability and environmental protection, adoption of a misfire detection technique has been studied also in motorcycle. In a four-wheel vehicle, the following techniques are known: in order to capture the variation in combustion torque due to misfire as a variation in crank angular velocity, the crank angular velocity is measured based on the generation time interval of the crank pulses (crank inter-pulse time), and the speed variation is used as a misfire parameter to detect the misfire of the engine.

However, since the crank angular velocity includes not only the tooth gap error of the crankshaft pulse rotor but also the disturbance due to the inertia torque, the pumping torque, the load friction, the auxiliary equipment, and the drive system, it is necessary to eliminate these error factors in order to perform accurate misfire determination.

In order to solve such a problem, patent document 1 discloses a misfire detection method using an ion current. In patent document 1, the presence or absence of misfire is detected by applying a voltage to the spark plug again in the middle of the expansion stroke immediately after the timing of main spark discharge for igniting the mixture gas in the cylinder and determining whether or not discharge has occurred in the cylinder at that time.

Patent document 1 is based on the following principle: since conductive ions are generated after normal combustion, ions are present in the vicinity of the electrode of the spark plug and cause re-ignition at a timing at which the required voltage required for breakdown is reduced, so that breakdown (discharge) occurs.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2003-222066

Problems to be solved by the invention

The misfire detection in patent document 1 is based on the fact that ions are generated after normal combustion, and therefore, the required voltage required for breakdown is reduced, but the ions deal with a weak current, and therefore, there is a problem in terms of noise toughness.

Disclosure of Invention

The present invention is directed to solving the above-described problems, and provides a misfire detection apparatus that focuses on the following situations: the relationship between the withstand pressure (japanese pressure) and the required breakdown voltage in the period in which the breakdown assistance by the ion is not provided, that is, the withstand pressure is relatively lower in the case of the misfire than in the case of the combustion, and therefore the required breakdown voltage is lower.

Means for solving the problems

In order to achieve the above object, the present invention is characterized in that the misfire detection apparatus 100 for an internal combustion engine that normally ignites the ignition plug 50 near the compression top dead center of the internal combustion engine to burn the air-fuel mixture has the following configuration.

(1) A first aspect of the present invention is a printer including: members 103 and 104 for additionally igniting the spark plug in an expansion stroke after normal ignition; and a means 105 for judging whether or not the spark plug has broken down due to additional ignition, and if it can be judged that the spark plug has broken down, judging the normal ignition as a misfire.

(2) A second feature of the present invention is that the means 105 for determining whether or not the breakdown has occurred determines whether or not the spark plug 50 has a breakdown on the basis of a voltage generated in the primary coil during a predetermined determination period after additional ignition by connecting the spark plug to the secondary coil of the ignition coil 10 in which the primary coil and the secondary coil are magnetically coupled and generating an induced voltage in the secondary coil by cutting off the current supply to the primary coil.

(3) In the third aspect of the present invention, the predetermined determination period is a time interval from a timing at which the voltage of the additional post-ignition primary coil after the normal-ignition normal combustion is substantially zero to a timing at which the voltage of the additional post-ignition primary coil after the normal-ignition misfire is substantially zero.

(4) A fourth feature of the present invention is that the spark plug 50 is connected to a secondary coil of the ignition coil 10 in which the primary coil and the secondary coil are magnetically coupled, and the means 105 for determining whether or not the breakdown occurs determines whether or not the spark plug has the breakdown based on a current flowing through the primary coil during a predetermined determination period after additional ignition by cutting off the current to the primary coil to generate an induced voltage in the secondary coil.

(5) In a fifth aspect of the present invention, the means 105 for determining whether or not the spark plug 50 is broken, which is connected to a secondary coil of the ignition coil 10 in which the primary coil and the secondary coil are magnetically coupled, and which generates an induced voltage in the secondary coil by cutting off the current supply to the primary coil, determines whether or not the spark plug is broken, based on a voltage generated in the secondary coil during a predetermined determination period after additional ignition.

(6) A sixth feature of the present invention is that the spark plug 50 is connected to a secondary coil of the ignition coil 10 in which the primary coil and the secondary coil are magnetically coupled, and the means 105 for determining whether or not the breakdown has occurred determines whether or not the spark plug has broken down, based on a current flowing through the secondary coil during a predetermined determination period after additional ignition, by cutting off the current to the primary coil to generate an induced voltage in the secondary coil.

Effects of the invention

According to the present invention, the following effects can be achieved.

(1) The present invention is provided with: means 103 and 104 for additionally igniting the spark plug in an expansion stroke after normal ignition; and a means 105 for judging whether or not the spark plug has broken down due to additional ignition, wherein if it can be judged that the spark plug has broken down, normal ignition is judged as misfire, so that it is possible to judge using the difference in breakdown required voltage based on the received pressure, and the toughness of misfire detection is improved.

(2) In the present invention, the means 105 for determining whether or not the breakdown has occurred determines whether or not the spark plug has broken down on the basis of the voltage generated in the primary coil during a predetermined determination period after additional ignition by the means for determining whether or not the breakdown has occurred by cutting off the current supply to the primary coil, the spark plug 50 being connected to the secondary coil of the ignition coil 10 in which the primary coil and the secondary coil are magnetically coupled, and the voltage of the primary side lower than the voltage of the secondary side can be used to detect misfire. Therefore, the mechanism for detecting the voltage can be simplified, reduced in weight, and inexpensive.

(3) In the present invention, the predetermined determination period is set to a time interval from a timing at which the voltage of the additional post-ignition primary coil after the normal ignition normal combustion is substantially zero to a timing at which the voltage of the additional post-ignition primary coil after the normal ignition misfire is substantially zero, so that the misfire can be detected at a timing at which the voltage difference between the normal combustion time and the misfire time appears remarkably and stably, and the toughness of the misfire detection can be improved.

(4) In the present invention, the means 105 for determining whether or not the breakdown has occurred determines whether or not the spark plug 50 has broken down, based on a current flowing in the primary coil during a predetermined determination period after additional ignition, by connecting the spark plug to the secondary coil of the ignition coil 10 in which the primary coil and the secondary coil are magnetically coupled, and by cutting off the current to the primary coil to generate an induced voltage in the secondary coil. Here, since the voltage generated in the primary coil and the current flowing in the primary coil show a high correlation, if the current flowing in the primary coil can be measured easily and accurately, the toughness of the misfire detection can be improved.

(5) In the present invention, the means 105 for determining whether or not the breakdown has occurred determines whether or not the spark plug 50 has broken down on the basis of the voltage generated in the secondary coil during a predetermined determination period after additional ignition by connecting the spark plug to the secondary coil of the ignition coil 10 in which the primary coil and the secondary coil are magnetically coupled and generating an induced voltage in the secondary coil by cutting off the current supply to the primary coil. Here, since the voltage generated in the primary coil and the voltage generated in the secondary coil show a high correlation, if the voltage of the secondary coil can be measured easily and accurately, the toughness of the misfire detection can be improved.

(6) In the present invention, the means 105 for determining whether or not the breakdown has occurred determines whether or not the spark plug 50 has broken down, based on a current flowing in the secondary coil during a predetermined determination period after additional ignition, by connecting the spark plug to the secondary coil of the ignition coil 10 in which the primary coil and the secondary coil are magnetically coupled, and by cutting off the current to the primary coil to generate an induced voltage in the secondary coil. Here, since the voltage generated in the primary coil and the current flowing in the secondary coil show a high correlation, if the current flowing in the secondary coil can be measured easily and accurately, the toughness of the misfire detection can be improved.

Drawings

Fig. 1 is a diagram showing a configuration of a main part of an engine ignition system including a misfire detection apparatus according to an embodiment of the present invention.

Fig. 2 is a diagram schematically showing changes in the pressure received in the cylinder in the case of normal ignition and normal combustion and in the case of misfire.

Fig. 3 is a diagram schematically showing changes in the primary-side voltage of the ignition coil in the case of normal ignition and normal combustion and in the case of misfire.

Fig. 4 is a flowchart showing the operation of an embodiment of the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present invention, in addition to the normal ignition in the vicinity of the compression Top Dead Center (TDC) which is fixedly determined or stably determined based on the engine speed or the like, the second ignition (additional ignition) is additionally performed in the expansion stroke after the normal ignition, and it is determined whether or not the misfire occurred in the immediately preceding normal ignition based on whether or not the breakdown occurred between the electrodes of the ignition plug due to the additional ignition.

Fig. 2 is a diagram schematically showing changes in the received pressure in the case of normal ignition and in the case of misfire, and when the air-fuel mixture in the cylinder is normally combusted by normal ignition near TDC, the received pressure in the cylinder rises and a correspondingly high received pressure is maintained also in the expansion stroke after TDC.

In contrast, in the case of the normal ignition misfire, the receiving pressure does not rise as much as in the case of combustion, and the receiving pressure in the expansion stroke after the TDC is shifted to fall at an earlier timing than in the case of normal combustion. Therefore, for example, when the pressure received in the middle of the expansion stroke is compared, the normal combustion time becomes relatively higher than the misfire time.

In the case of a normal ignition misfire, the withstand pressure becomes lower than that in the case of normal combustion, and therefore the breakdown request voltage is relatively lowered. Therefore, by appropriately setting the second applied voltage lower than the first applied voltage for normal ignition, it is possible to generate breakdown between the electrodes of the ignition plug only at the time of misfire.

On the other hand, the inventors of the present invention compared the voltage change of the primary side coil of the ignition coil between the case where the breakdown occurs due to the additional ignition and the case where the breakdown does not occur, and as a result, as shown in fig. 3, confirmed that a significant difference is stably generated in a predetermined time period of the expansion stroke immediately after the normal ignition, in particular, depending on the presence or absence of the breakdown.

Specifically, it was confirmed that a significant and stable difference was generated between the timing when breakdown did not occur in the spark plug (in fig. 3, approximately 120 μ Sec after additional ignition) and the timing when breakdown occurred (approximately 160 μ Sec after additional ignition) in the voltage of the primary side coil of the ignition coil at the time of additional ignition. The reason why such a time period occurs is considered as follows.

That is, when breakdown does not occur due to additional ignition, magnetic energy accumulated on the secondary side of the ignition coil is attenuated by the resistance of the circuit, and electric charge movement (resonance) due to the electrostatic capacitance of the coil and the secondary circuit is caused. This resonance phenomenon generates a magnetic flux change, and induces a voltage in the primary coil. If a diode is provided in the primary-side coil, it is possible to suppress the current induced in the secondary-side coil from becoming positive in the diode, that is, the potential of the primary side from becoming negative to a large extent. At this timing, the potential of the primary coil is substantially zero.

When a breakdown occurs due to additional ignition, the magnetic energy accumulated in the secondary coil is released on the spark plug side. The primary coil voltage is induced by magnetic flux generated by the potential change of the secondary coil. The voltage of the primary side coil changes slowly until the discharge on the spark plug side ends, and becomes substantially zero.

Therefore, in the present embodiment, the applied voltage (second applied voltage) at the time of additional ignition is set to an appropriate value lower than the applied voltage (first applied voltage) at the time of normal ignition, which is a voltage as follows: although breakdown does not occur if the mixture is normally combusted by the normal ignition, breakdown occurs if the normal ignition is misfired, whether the normal ignition has misfired is detected by observing a change in voltage on the primary side of the ignition coil at the timing of additional ignition.

Fig. 1 is a diagram showing a configuration of a main part of an engine ignition system 1 including a misfire detection apparatus 100 according to an embodiment of the present invention.

The ignition unit 20 is connected in series to the primary side of the ignition coil 10, and the battery 30 is connected in parallel to the series connection. The voltage detection circuit 40 is connected in parallel to the ignition unit 20. The primary-side voltage V detected by the voltage detection circuit 40 is output to the misfire detection apparatus 100. A spark plug 50 is connected to the secondary side of the ignition coil 10.

In the ignition unit 20, one end of the primary coil is connected to a collector terminal of a transistor Tr serving as a current cut-off switch with an emitter grounded, and a zener diode D1 is connected in parallel between the emitter and the base. An ignition signal P (P1, P2) is input from the misfire detection apparatus 100 to the base terminal of the transistor Tr.

The crank pulse sensor 80 is connected to the misfire detection apparatus 100. The crank pulse sensor 80 detects the rotational position of the crank pulse rotor 70 that rotates in synchronization with the crankshaft 60 of the engine, and outputs a crank pulse signal near the compression top dead center of the engine.

In the misfire detection apparatus 100, the normal ignition timing calculation section 101 calculates the normal ignition timing based on the output signal of the crank pulse sensor 80 and the engine parameters such as the engine speed and the throttle opening degree. The normal ignition signal generating section 102 generates a normal ignition signal P1 at the normal ignition timing.

The additional ignition timing calculation unit 103 calculates a predetermined timing of the expansion stroke immediately after the normal ignition as an additional ignition timing. In the present embodiment, as shown in fig. 2, the crank angle range from TDC to 90 ± 10deg is set as the additional ignition timing. The additional ignition signal generating unit 104 generates an additional ignition signal P2 at the additional ignition timing. Therefore, the misfire detection device 100 outputs the normal ignition signal P1 and the additional ignition signal P2 at the respective timings.

The breakdown determination unit 105 determines whether or not the ignition coil 10 has broken down due to the application of the additional second voltage for ignition, based on the output of the voltage detection circuit 40. Here, as shown in fig. 3, the primary-side voltage V after the additional ignition timing tends to be as follows: during normal combustion, the voltage decreases so as to decrease rightward, while during misfire, the change in the secondary-side current due to breakdown decreases later than during normal combustion, and a significant difference is observed between the time of normal combustion and the time of misfire until the primary-side voltage V becomes substantially zero.

Therefore, in the present embodiment, as a time period from a timing at which the primary-side voltage V (V1) at the time of normal combustion after the additional ignition timing is substantially zero (about 120 μ Sec after TDC) to a timing at which the primary-side voltage V (V2) at the time of misfire is substantially zero (about 160 μ Sec after TDC), for example, 140 ± 20 μ Sec after the additional ignition is set as the determination period.

The time period from the timing at which the primary-side voltage V1 at the time of normal combustion after the addition of the ignition timing is substantially zero to the timing at which the primary-side voltage V2 at the time of misfire is substantially zero depends on the engine specification and the operating state of the engine. Therefore, the determination period is not limited to 140 ± 20 μ Sec described above, and is preferably set as appropriate according to the ignition circuit characteristics, the engine specification, the operating state of the engine, and the like.

The breakdown determination unit 105 compares the primary-side voltage V of the ignition coil 10 detected during the determination period with a predetermined determination threshold Vref, and determines that breakdown has occurred due to additional ignition if V is greater than or equal to Vref. The misfire detection apparatus 100 detects that the immediately preceding normal ignition has misfired based on the fact that the breakdown determination section 105 determines that the breakdown has occurred.

Such a misfire detection apparatus 100 can be configured by installing an application (program) that realizes each function described later in a general-purpose computer or ECU including a CPU, a memory, an interface, a bus connecting these components, and the like. Alternatively, a part of the application may be configured as a dedicated machine or a single-purpose machine that is realized by hardware or programmed.

Fig. 4 is a flowchart showing the operation of the present embodiment, and the additional ignition timing is set to 90deg as the crank angle index, the timing for detecting the primary side voltage of the ignition coil 10 is set to 140 μ Sec from the additional ignition timing, and then the time for conducting current to the primary side of the ignition coil 10 to prepare for additional ignition is set to 175 μ Sec.

In step S1, a normal ignition timing is calculated based on the crank pulse signal and the engine parameter. Then, the timing from the normal ignition timing to the energization time for energization ignition to the primary coil of the ignition coil 10 is calculated as the energization start timing for normal ignition.

When the energization start timing for the normal ignition is reached in step S2, the routine proceeds to step S3, and energization for ignition to the primary coil is started. In step S4, it is determined whether or not the determined normal ignition timing is reached. When the normal ignition timing is reached, the routine proceeds to step S5, and normal ignition is performed.

In step S6, the standby time wt until the additional ignition timing (90 deg after TDC) is calculated based on the current crank angle and the engine speed. In step S7, it is determined whether or not wt.ltoreq.175 μ Sec. If not, the weight is less than 175 μ Sec, the process returns to step S6 and stands by.

If it is determined in step S7 that wt is not greater than 175 μ Sec, the routine proceeds to step S8, where energization for additional ignition to the primary coil of the ignition coil 10 is started. In step S9, it is determined whether the ignition timing is the additional ignition timing based on the crank angle. When the crank angle is calculated to be 90deg by the additional ignition timing calculation unit 103, it is determined that the ignition timing is additional ignition timing, and the routine proceeds to step S10.

In step S10, the additional ignition signal generating unit 104 outputs an additional ignition signal P2 to attempt additional ignition. At this time, since 175 μ Sec has elapsed as the energization time to the primary coil, a predetermined voltage (second applied voltage) lower than that at the time of normal ignition is applied to the ignition plug 50 by additional ignition.

In step S11, an elapsed time timer t is started. In step S12, it is determined whether or not it is the voltage detection timing based on the timer t. If not, the process returns to step S12.

Thereafter, when the timer t reaches 140 μ Sec, it is determined as the voltage detection timing and the process proceeds to step S13. In step S13, the primary-side voltage V of the ignition coil 10 is detected. In step S14, breakdown determination unit 105 compares primary-side voltage V with breakdown determination threshold value Vref, and determines that misfire occurred during normal ignition due to breakdown occurring if V ≧ Vref, and determines that normal ignition is burning normally due to no breakdown occurring if V < Vref.

According to the present embodiment, since misfire detection is performed based on the primary side voltage of the ignition coil at the time of additional ignition in the expansion stroke immediately after normal ignition, which significantly changes depending on whether or not misfire occurs in normal ignition, the misfire detection using the difference in breakdown required voltage based on the receiving pressure can be performed, and the toughness of the misfire detection improves.

Further, according to the present embodiment, it is determined whether or not the spark plug has broken down based on the voltage generated in the primary side coil by the additional ignition, and therefore, the misfire can be detected based on the voltage of the primary side having a lower voltage than the secondary side. Therefore, the mechanism for detecting the voltage can be simplified, reduced in weight, and inexpensive.

Further, according to the present embodiment, since the determination period is set to a time interval from a timing at which the voltage of the additional post-ignition primary side coil after the normal ignition normal combustion is substantially zero to a timing at which the voltage of the additional post-ignition primary side coil after the normal ignition misfire is substantially zero, the misfire can be detected at a timing at which the voltage difference between the normal combustion and the misfire appears remarkably and stably, and the toughness of the misfire detection can be improved.

In the above-described embodiment, the determination of the presence or absence of misfire based on the primary-side voltage V of the ignition coil 10 has been described, but the present invention is not limited to this, and since a high correlation is observed between the primary-side voltage V and the primary-side current, the voltage of the secondary side, and the current, the presence or absence of misfire may be determined based on the primary-side current, the voltage of the secondary side, and the current.

If the misfire can be detected based on the current of the primary side coil of the ignition coil 10, the misfire can be accurately detected even when it is difficult to monitor the primary side coil voltage, for example, when the igniter is disposed outside the ECU.

Further, if the misfire can be detected based on the voltage/current of the secondary side coil of the ignition coil 10, even when it is physically difficult to access the primary side coil, the misfire can be accurately detected based on the voltage/current of the secondary side coil.

Description of the reference numerals

1 engine ignition system, 10 ignition coil, 20 ignition unit, 30 storage battery, 40 voltage detection circuit, 50 spark plug, 60 crankshaft, 70 crankshaft pulse rotor, 80 crankshaft pulse sensor, 100 misfire detection device, 101 normal ignition timing calculation section, 102 normal ignition signal generation section, 103 additional ignition timing calculation section, 104 additional ignition signal generation section, 105 breakdown determination section