JP2002202000A - Misfire detecting device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the presence or absence of the occurrence of misfire with high accuracy even when a combustion condition is changed on the basis of an operating condition of a tumble generator valve. SOLUTION: A TGV operation detecting means 32 detects an operating condition of the tumble generator valve(TGV) producing tumble current in a combustion chamber on the basis of an output signal of a TGV sensor 15a. A misfire determination correction value calculating means 33 selects a misfire determination correction value map prepared for every TGV operating condition on the basis of the TGV operating condition, refers the selected misfire determination correction value map while applying a cooling water temperature as a parameter, and sets the misfire determination correction value Kmf. A misfire determination threshold value setting means 34 sets a base misfire determination threshold value on the basis of an engine speed Ne and the engine load Lo, corrects the base misfire determination threshold value on the basis of the misfire determination correction value Kmf, and sets the misfire determination threshold value LSL. Then the variation of rotation ω determined by a variation of engine rotation operating means 31 is compared with the misfire determination threshold value LSL by a misfire determining means 35, and the misfire is determined in a case of ω>LSL. As the misfire determination threshold value LSL is corrected in accordance with the operating condition of the TGV, the accuracy in detecting the misfire is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a misfire of an engine for variably setting a misfire determination threshold value which is a reference value for detecting the presence or absence of a misfire in accordance with the operation state of an intake control valve for variably setting a combustion state. It relates to a detection device.

[0002]

2. Description of the Related Art Conventionally, this type of misfire detection device utilizes a phenomenon in which an engine speed decreases due to a decrease in torque due to the occurrence of a misfire, and the amount of fluctuation between the previous engine speed and the current engine speed. Is detected, and when the engine rotation fluctuation amount is larger than a misfire determination threshold value, a technique of judging misfire is generally adopted in many cases.

However, when an attempt is made to detect a misfire based on the amount of fluctuations in engine rotation, in a region susceptible to disturbance, no misfire is detected despite the fact that a misfire actually occurs, or conversely, In some cases, a misfire is erroneously determined even though no misfire has actually occurred.

[0004] For example, when the engine operating state is a low load operation or at a high rotation speed, the engine rotation fluctuation is liable to occur due to the influence of disturbance, and the engine rotation fluctuation amount becomes large even though no misfire has occurred. In addition, even when a misfire has actually occurred, the engine rotation fluctuation amount may be small.

[0005] Therefore, for example, Japanese Patent Application Laid-Open No. Hei 5-231231
In the publication, when the engine rotation fluctuation amount at the time of misfire detection is larger than the misfire determination threshold value, a forced misfire is performed immediately thereafter, and the engine rotation fluctuation amount at the time of the forced misfire is larger than the engine rotation fluctuation amount at the time of misfire determination. In such a case, a technique is disclosed in which the misfire determination at the time of the misfire determination is prohibited, and the misfire determination threshold value is updated with the fluctuation amount at the time of the forced misfire.

[0006]

However, in the above-mentioned prior art, the misfire determination threshold is updated with the fluctuation amount at the time of the forced misfire in order to enhance the detection accuracy of the misfire. There is a problem that exhaust emissions deteriorate due to the misfire caused.

By the way, a tumble flow, which is an axial swirl flow, and a swirl flow in the circumferential direction of the shaft are provided in the combustion chamber in order to improve the stability of combustion, the promotion of combustion speed, the improvement of fuel efficiency, etc. at the time of low / medium load operation. There is known a technique in which an intake control valve for generating a swirl flow such as a swirl flow is provided in an intake system.

[0008] Such an engine having an intake control valve is widely used in engines and the like. However, the operation of the intake control valve causes a sudden sudden change in the amount of intake air. appear.

At this time, as in the above-mentioned prior art, if an attempt is made to detect a misfire by generating a forced misfire, the combustion state greatly fluctuates due to the forced misfire, leading to deterioration in ride comfort and exhaust emission. There is a problem.

[0010] When the intake control valve is closed and when it is opened,
The amount of intake air flowing into the combustion chamber and its flow are different,
Since the combustion state in the combustion chamber changes, the output torque characteristics change. Therefore, if an attempt is made to detect the occurrence of misfire based on the amount of engine rotation fluctuation, the rotation fluctuation during normal combustion may be erroneously determined to be misfire depending on the operation state of the intake control valve. When the misfire determination threshold is set in consideration of the above, the misfire determination threshold is set to a large value, and there is a problem that the misfire detection accuracy is reduced.

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a highly reliable engine misfire that can accurately detect the presence or absence of a misfire without being affected by the operation state of the intake control valve. It is an object to provide a detection device.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, a first aspect of the present invention is to provide an engine having an intake control valve for generating a vortex in a combustion chamber in an intake system. Fluctuation amount calculation means, misfire determination means for comparing the engine rotation fluctuation amount calculated by the engine rotation fluctuation amount calculation means with a misfire determination threshold value to determine engine misfire, and setting the misfire determination threshold value to the intake control valve. And a misfire determination correction value calculating means for calculating a misfire determination correction value to be corrected in accordance with an operation state.

In such a configuration, when the misfire determination of the engine is performed by comparing the engine rotation fluctuation amount with the misfire determination threshold value, the misfire determination threshold value is corrected according to the operation state of the intake control valve provided in the intake system. By doing so, the accuracy of misfire detection is improved.

In this case, preferably, 1) the misfire determination correction value calculated by the misfire determination correction value calculation means has different characteristics at the fully open position, the fully closed position, and the middle open position of the intake control valve. It is characterized by being variably set based on characteristics.

2) The misfire judgment correction value calculated by the misfire judgment correction value calculation means is set based on a factor that the engine speed is likely to fluctuate greatly due to disturbance.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration diagram of the engine. Reference numeral 1 in FIG. 1 denotes an engine body, and a spark plug 2 faces a combustion chamber 1 a of the engine body 1.
The cylinder head 3 is provided with an intake port 4 and an exhaust port 5 that communicate with the combustion chamber 1a.

An intake passage 6 communicates with the intake port 4 via an intake manifold 7, and an air cleaner 8 is disposed upstream of the intake passage 6. Further, a throttle valve 9 is provided in the middle of the intake passage 6. On the other hand, a catalyst 11 is interposed in the exhaust passage 10 communicating with the exhaust port 5.

The intake manifold 7 is provided with a partition wall 12 for vertically separating the inside of the intake manifold 7, and the partition wall 12 partitions the inside of the intake manifold 7 into a sub-passage 13 having a small passage area and a main passage 14 having a large passage area. I have.

At the upstream end of the main passage 14, a tumble generation valve (TGV) 15 as an intake control valve capable of opening and closing the main passage 14 is provided.
An injector 16 is disposed upstream of the sub-passage 13 with the injection port directed toward the intake port 4.

Further, a water temperature sensor 17 for detecting a cooling water temperature, which is representative of the engine temperature, is provided in the engine body 1,
An intake air amount sensor 18 for detecting an intake air amount is provided immediately downstream of the air cleaner 8 in the intake passage 6, and a throttle valve 9 is provided.
Throttle opening sensor 19 for detecting the throttle opening
The TGV 15 is provided with a TGV sensor 15a for detecting the operation state of the TGV 15, and the exhaust passage 1
An O2 sensor 20 is disposed upstream of the zero catalyst 11.

The TGV sensor 15a is composed of, for example, a double switch.
N, and the other switch is set to be turned ON when the TGV is fully opened. Therefore, when both switches are OFF,
It can be detected that the TGV 15 is in a transition state in which the state is switched (hereinafter, this state is referred to as “medium opening”). The TGV sensor 15a may be a normal opening sensor that detects the valve opening.

Reference numeral 30 denotes an electronic control unit (ECU).
A water temperature sensor 1 is provided on the input side of the electronic control unit 30.
7. Intake air amount sensor 18, throttle opening sensor 1
9, an O2 sensor 20, an engine speed sensor 21 for detecting the engine speed, and other sensors and switches for detecting the engine operating state are connected. On the output side, an injector driving actuator (for driving the injector 16) Various drive actuators such as a TGV drive actuator 15b for driving the TGV 15;
And an ignition drive circuit 2 a for outputting an ignition drive signal to the ignition plug 2.

The electronic control unit 30 executes fuel injection control, ignition timing control, TGV control, and the like based on signals from sensors and switches for detecting the engine operating state, and detects the occurrence of misfire.

In the TGV control, when the engine operation state is low,
During the medium load operation, the TGV drive actuator 15
Outputs a close signal for b. Then, the TGV 15 performs a valve closing operation to close the main passage 14. As a result, the intake air passes through the auxiliary passage 13 at an increased flow velocity, and generates a tumble flow in the combustion chamber 1a. In the combustion chamber 1a, the gas flow is strengthened by the tumble flow, and the combustion speed is promoted.

On the other hand, when the engine operating state is high load operation, an open signal is output to the TGV drive actuator 15b. Then, the TGV 15 is opened, and the intake air passes through both the main passage 14 and the sub-passage 13 and the combustion chamber 1
Flows to a. When the TGV 15 opens, the TGV 15
And the generation of the tumble flow is suppressed, the amount of intake air flowing into the combustion chamber 1a increases, and the engine output improves.

As described above, the main passage 1 is controlled by the TGV 15.
When the valve 4 is opened and closed, the passage area of the intake manifold 7 changes, and the air flow rate and the inflow path into the combustion chamber 1a change. As a result, the state of the intake air flowing into the combustion chamber 1a changes, and the combustion mode changes.

Further, as shown in FIG.
Are functions for detecting the occurrence of a misfire, such as an engine rotation fluctuation amount calculating means 31, a TGV operation detecting means 32, a misfire determination correction value calculating means 33, a misfire determination threshold value calculating means 34,
A misfire determination means 35 is provided.

The engine speed variation calculating means 31 calculates the engine speed Ne detected by the engine speed sensor 21.
Is read for each ignition, and the engine speed N at the time of the previous ignition is read.
From the difference between e and the engine speed Ne at the time of the current ignition, the rotation fluctuation amount ω is calculated to be a positive number.

The TGV operation detecting means 32 detects the operation state (full open, middle open, fully closed) of the TGV 15 based on the output signal from the TGV sensor 15a.

The misfire determination correction value calculation means 33 selects a map to be referred to based on the TGV operation state detected by the TGV operation detection means 32, and causes the engine speed such as the cooling water temperature to fluctuate greatly under the influence of disturbance. Misfire determination correction value K for correcting a base misfire determination threshold value BSL described later based on
Set mf.

The misfire determination threshold value calculation means 34 sets a base misfire determination threshold value BSL with reference to a base misfire determination threshold value map based on the engine load Lo detected by the engine load detection means 37 and the engine speed Ne. Then, the base misfire determination threshold value BSL is corrected by the misfire determination correction value Kmf, and the misfire determination threshold value LS corresponding to the TGV operation state is obtained.
Set L. The engine load detecting means 37 employs a representative intake air amount sensor 18 or throttle opening degree sensor 19, and the intake air amount Q detected by the intake air amount sensor 18 and the throttle opening degree sensor 19 detect the engine load. The throttle opening θth obtained may be used as the engine load Lo.

Then, the misfire judging means 35 compares the rotation fluctuation amount ω with the misfire judgment threshold LSL. If ω> LSL, it is judged as “misfire”, and if ω ≦ LSL, it is judged as “normal”. And output the result.

When it is determined that a misfire has occurred, for example, the number of misfires is counted for each cylinder. When a predetermined value is reached, a warning lamp is turned on and the misfire cylinder is displayed.

Next, according to the flowchart shown in FIG.
The misfire detection routine processed by the electronic control unit 30 will be specifically described.

This routine is started for each ignition. First, in step S1, the engine speed Ne detected by the engine speed sensor 21 is read, and in step S2, the engine load Lo detected by the engine load detecting means 37 is read. Put in. In this embodiment, an intake air amount sensor 18 or a throttle opening sensor 19 is employed as a representative of the engine load detecting means 37, and the intake air amount Q detected by these sensors 18 and 19, or the throttle opening degree is used. θth is used as the engine load Lo.

Then, the process proceeds to a step S3, wherein the previously detected engine speed Ne and the currently detected engine speed N
The difference from e is calculated, and the rotation fluctuation amount ω is calculated to be a positive number.

Thereafter, the process proceeds to step S4, and based on the engine speed Ne and the engine load Lo, a base misfire determination threshold value BSL is set by referring to a base misfire determination threshold value map with interpolation calculation. As shown in FIG. 4, the base misfire determination threshold map stores a larger base determination value BSL as the engine speed Ne is lower and the engine load Lo is higher. That is, in the normal operation after the completion of the warm-up, the engine speed fluctuation ω during misfire increases as the engine speed Ne decreases and the engine load Lo increases, so that the engine speed fluctuation ω during normal combustion is disturbed. A large base determination value BSL is set with a margin so that erroneous misfire determination can be prevented even if it is affected by the misfire. Further, as the engine speed Ne is higher and the engine load Lo is lower, the engine rotation fluctuation amount ω at the time of misfire becomes smaller and the difference from the engine rotation fluctuation amount ω at the time of normal combustion becomes smaller, so that erroneous determination can be prevented. It is necessary to set a small base determination value BSL.

Next, the process proceeds to step S5, where the output signal of the TGV sensor 15a is read, and the operating state of the TGV 15 is detected. For example, the TGV sensor 15a is configured by a double switch. One switch (this is temporarily referred to as a first switch) is turned on when the TGV is fully closed, and the other switch (this is temporarily referred to as a second switch) is turned on. ON when TGV is fully open
If both switches are set to ON
By reading the / OFF signal, it is possible to detect that the operation state of the TGV 15 is any of Table 1.

[0039]

[Table 1]

Then, the process proceeds to step S6,
In S6, based on the output signal of the TGV sensor 15, T
The operation state of the GV 15 is determined, and a misfire determination correction value map corresponding to the operation state of the TGV 15 is selected.

That is, when the TGV 15 is fully open, the process proceeds from step S6 to step S8, where the misfire determination correction value map when the TGV is fully opened is selected, and the misfire determination correction value map is detected by the coolant temperature Tw detected by the coolant temperature sensor 17. Then, the misfire determination correction value Kmf is calculated with reference to interpolation calculation.

If the TGV 15 is fully closed, step S
Then, the process proceeds from step 7 to step S9, in which a misfire determination correction value map when the TGV is fully closed is selected.
Compute mf. Also, when the TGV 15 is in the middle open state, that is, in the transition state of switching from the fully closed state or the fully open state,
Proceeding to step S10, the TGV intermediate misfire determination correction value map is selected, and the misfire determination correction value Kmf is calculated based on the cooling water temperature Tw with reference to interpolation calculation.

FIG. 5 shows a misfire determination correction value map when the TGV is fully opened, FIG. 6 shows a misfire determination correction value map when the TGV is fully closed, and FIG. As shown in the figure, each map stores a misfire determination correction value Kmf that is larger as the coolant temperature Tw is lower.

The TGV 15 basically controls either the fully closed operation or the fully open operation. However, by providing a misfire determination correction value map when the TGV is opened during the TGV 15 operation, that is, when the TGV 15 is switched, that is, when the combustion state is changed. Even when misfire is determined in a region where the output torque characteristic changes due to change, misfire detection can be performed with high accuracy.

Incidentally, the misfire determination correction value Kmf stored in the TGV fully closed misfire determination correction value map of FIG. 6 or the TGV middle open misfire determination correction value map of FIG. 7 is almost equal to the rise of the cooling water temperature Tw. The misfire determination correction value Kmf stored in the TGV fully-open misfire determination correction value map of FIG.
It is set to a large value until w rises to some extent.

The reason is that when the TGV 15 is fully closed or medium open, a swirl flow is generated in the combustion chamber 1a and the gas flow is strengthened, so that combustion is ensured even if the cooling water temperature Tw is somewhat low. be able to. Therefore, the engine rotation fluctuation amount ω is reduced almost in proportion to the rise of the cooling water temperature Tw.

On the other hand, when the TGV 15 is fully opened, the combustion chamber 1a
Since the generation of the tumble flow generated in the chamber acts in a direction that is rather suppressed, and the atomization of the fuel cannot be promoted, the engine rotation fluctuation amount ω even in the normal combustion until the cooling water temperature Tw rises to some extent. Tends to be large. Therefore, as shown in FIG. 5, the misfire determination correction value Kmf is different from the cooling water temperature Tw.
Is set to the change characteristic of the convex state with respect to the rise of

Next, the process proceeds to step S11, in which the base misfire determination threshold value BSL set in step S4 is corrected (multiplied) by the misfire determination correction value Kmf to calculate a misfire determination threshold value LSL.

Then, the process proceeds to step S12, where the rotation fluctuation amount ω is compared with the misfire determination threshold LSL. If ω> LSL, the process proceeds to step S13, where misfire is determined, and the routine exits. On the other hand, if ω ≦ LSL, step S14
Then, it is determined as normal, and the routine is exited.

When it is determined that a misfire has occurred, in another routine, for example, the number of misfires is counted for each cylinder, and when any of the misfires reaches a predetermined value, a warning light provided on the instrument panel is activated. Turn on the light and display the misfiring cylinder.

As described above, according to the present embodiment, the base misfire determination threshold value BSL set based on the engine speed Ne and the engine load Lo is corrected according to the operating state of the TGV 15. The presence or absence of a misfire can be detected with high accuracy.

That is, the amount and flow of the intake air flowing into the combustion chamber 1a changes according to the operating state of the TGV 15, and the fluctuation characteristics of the output torque change. Therefore, by correcting the base misfire determination threshold value BSL according to the operation state of the TGV 15, the misfire detection accuracy can be improved.

Further, in the present embodiment, the misfire determination correction value Kmf set for each operating state of the TGV 15 can be varied based on factors such as the cooling water temperature Tw, which are likely to cause the engine speed to fluctuate greatly under the influence of disturbance. Because I set it,
An appropriate misfire determination correction value Kmf can be set.

As a result, an appropriate misfire determination threshold value LSL according to the combustion characteristics of the engine is set, and no misfire is detected in spite of the fact that misfire has actually occurred, or conversely, misfire has actually occurred. The misfire is not erroneously determined even though no misfire has occurred, and the misfire detection accuracy is greatly improved.

The parameter for setting the misfire determination correction value Kmf stored in each misfire determination correction value map is a parameter that can detect a factor that easily changes the engine speed under the influence of disturbance. , Not only the cooling water temperature Tw,
Engine speed Ne, intake air amount Q, throttle opening θ
th, the engine load Lo, the intake air temperature, or the like.

In this case, each misfire determination correction value map includes
Misfire determination correction value K having characteristics corresponding to these parameters
mf is stored. For example, as shown in FIG. 8, the misfire determination correction value Kmf is changed from the engine speed Ne to the engine load Lo.
May be set by using a map having parameters as parameters. In this case, as the engine speed Ne is lower and the engine load Lo is higher, the engine rotation fluctuation amount ω is likely to be larger due to the influence of disturbance. Therefore, a large misfire determination correction value Kmf is stored.

[0057]

As described above, according to the present invention,
In detecting the occurrence of a misfire by comparing the engine rotation fluctuation amount with the misfire determination threshold, the misfire determination threshold is corrected according to the operation state of the intake control valve. It is possible to set a misfire determination threshold value corresponding to a change in the combustion state caused by the misfire. Therefore, the presence / absence of misfire can be determined with high accuracy, and high reliability can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an engine.

FIG. 2 is a block diagram showing a misfire determination function of the electronic control unit.

FIG. 3 is a flowchart showing a misfire detection routine.

FIG. 4 is an explanatory diagram of a base misfire determination threshold map.

FIG. 5 is an explanatory diagram of a misfire determination correction value map when the TGV is fully opened.

FIG. 6 is an explanatory diagram of a misfire determination correction value map when the TGV is fully closed.

FIG. 7 is an explanatory diagram of a TGV middle-open misfire determination correction value map.

FIG. 8 is an explanatory diagram of a TGV middle-open misfire determination correction value map according to another embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine main body 1a Combustion chamber 15 Tumble generation valve (intake control valve) 31 Engine rotation fluctuation amount calculation means 33 Misfire determination correction value calculation means 35 Misfire determination means BSL Base misfire determination threshold value (misfire determination threshold value) Kmf Misfire determination correction value Tw Cooling water temperature ω Engine rotation fluctuation

Continued on the front page F-term (reference) 2G087 AA13 BB14 CC01 DD15 EE14 FF23 FF40 3G084 BA11 BA17 BA21 CA03 CA04 DA27 EA11 EB11 EB22 FA00 FA07 FA10 FA20 FA24 FA29 FA33 FA34 3G092 AA10 BA09 BB01 BB06 EC06 EC06 HC06 EC06 HC06 EC06 HD05Z HE01Z HE02Z HE08Z

Claims (3)

[Claims] 1. An engine provided with an intake control valve for generating a vortex in a combustion chamber in an intake system, an engine rotation fluctuation calculating means for calculating an engine rotation fluctuation, and an engine calculated by the engine rotation fluctuation calculating means. Misfire determination means for comparing the amount of rotation fluctuation with a misfire determination threshold to determine misfire of the engine; and misfire determination correction for calculating a misfire determination correction value for correcting the misfire determination threshold according to the operation state of the intake control valve. An engine misfire detection device comprising a value calculation unit. 2. The misfire determination correction value calculated by the misfire determination correction value calculation means includes a fully open position, a fully closed position,
The misfire detection device for an engine according to claim 1, wherein the misfire detection device has different characteristics at the middle position and the middle open position, and is variably set based on each characteristic. 3. The misfire determination correction value calculated by the misfire determination correction value calculation means is set based on a factor that causes the engine speed to fluctuate greatly under the influence of disturbance. Engine misfire detection device.