JPH0783101A - Trouble detecting device of internal combustion engine - Google Patents

Abstract

PURPOSE:To optimize a combustion condition by accurately detecting any trouble of a swirl control valve (SCV), and switching an ignition timing at the time of the trouble. CONSTITUTION:An operational condition of an engine is found out from the signal of a crank angle sensor 28, etc., and a combustion term from the time of ignition, during normal operation determined by an operation condition, to the time when a cylinder inside pressure reaches a peak value is detected, and a real combustion term is detected from a signal of a cylinder inside pressure sensor 22. It is judged whether opening/closing trouble is generated at a SCV 23 or not by comparing the combustion term at the normal time with the real combustion term, and the combustion condition is made optimum by switching an ignition timing map at the time of trouble, and making a crank angle at the time when the cylinder inside pressure reaches the peak value as MBT (maximum combustion term).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine failure detecting device for detecting a failure of a swirl control valve of an internal combustion engine.

[0002]

2. Description of the Related Art In an internal combustion engine that performs lean combustion, a swirl control valve is provided in each branch portion of an intake manifold, and the swirl is strengthened by closing the swirl control valve in a predetermined operating condition. Combustion and combustion near the stoichiometric air-fuel ratio are optimized.

Therefore, if the swirl control valve is defectively opened or closed, problems such as ignition delay occur during lean combustion. Therefore, the open sensor for detecting the open state and the closed state of the swirl control, respectively. , The closing sensor is installed in the link mechanism of the swirl control valve, and the valve opening failure and valve closing failure of the swirl control valve are mechanically detected based on the detection signals of these sensors, and the target air-fuel ratio and ignition timing are adjusted. Such an arrangement is known, for example, from Japanese Patent Application Laid-Open No. 62-223440.

[0004]

However, in the case where the above-mentioned sensors for detecting the open state and the closed state of the swirl control valve are provided, each sensor is opened by contacting the link mechanism of the swirl control valve. The reliability is low because the valve state and the valve closed state are detected. That is, in the limit switches often used for these sensors, there is a possibility that they may not work reliably due to fusion of contacts, poor contact, sticking of the plunger, and the like, and these sensors and swirl control valves may not work together. The swirl control valve failure detection accuracy is low.

Further, since two sensors are separately provided in the link mechanism for detecting the swirl control valve failure, the number of parts and the number of assembling steps increase, and the mechanical structure becomes complicated.

[0006]

Therefore, the present invention detects a combustion state parameter representing the combustion state based on the detection signal of the in-cylinder pressure detection means, and determines the combustion state under normal condition obtained from the combustion state parameter and the operating state. By comparing it with the parameter, the swirl control valve is judged to be defective and the operating condition of the internal combustion engine is optimized. That is, as shown in FIG. 1, an in-cylinder pressure detecting means 1 for detecting the in-cylinder pressure of an internal combustion engine, and a combustion state for detecting a combustion state parameter indicating a combustion state based on a detection signal of the in-cylinder pressure detecting means 1. Detecting means 2, operating state detecting means 3 for detecting the operating state of the internal combustion engine, and operating state detecting means 3
Normal combustion state setting means 4 for setting the normal combustion state parameter based on the detection signal of 1, the combustion state parameter detected by the combustion state detecting means 2 and the normal combustion state parameter set by the normal combustion state setting means 4. A failure determination means 5 for determining whether or not the swirl control valve of the internal combustion engine has failed, and a predetermined failure control when the failure determination means 5 determines that the swirl control valve has failed. The operation state switching means 6 for switching to.

[0007]

For example, if the swirl control valve is out of order during lean combustion of the engine, the combustion is delayed because the swirl is weak, and the combustion state parameter in this case differs from the normal combustion state parameter. Also,
If a malfunction occurs with the swirl control valve closed while operating near the stoichiometric air / fuel ratio, the swirl is so strong that combustion accelerates, and there is a difference between the combustion state parameter and the normal combustion state parameter in this case. Occurs.

Therefore, in the failure determination means 5, the actual combustion state parameter detected by the combustion state detection means 2 based on the detection signal of the in-cylinder pressure detection means 1 and the normal combustion state setting means 4 in the operating state detection means 3. By comparing with the normal combustion state parameter set based on the detection signal, it is determined whether the swirl control valve is out of order. If the swirl control valve is out of order, the operating state switching means 6 Switches the internal combustion engine to a control for a predetermined failure.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS.

First, FIG. 2 is a structural explanatory view of a failure detecting device for an internal combustion engine according to an embodiment of the present invention. In the figure, a piston 12 is slidably provided in a cylinder 11 of the internal combustion engine. A combustion chamber 13 is formed in the upper part of the cylinder 11 by 12. Intake passage 14 in combustion chamber 13
Are connected via an intake valve 15, and an exhaust passage 16 is connected via an exhaust valve 17.
In the middle of 4, an air flow meter 1 for detecting the amount of intake air
8 and throttle valve 1 for variably adjusting the intake air amount
9, a swirl control valve 23, which will be described later, for generating a swirl, a fuel injection valve (not shown), and the like are provided. Further, the exhaust passage 16 is provided with an oxygen sensor that detects the residual oxygen concentration in the exhaust gas, a catalytic converter (not shown) that removes combustion products such as HC, and the like.

The cylinder head 11A of the cylinder 11 is provided with an ignition plug 20 with its front end facing the inside of the combustion chamber 13, and the ignition plug 20 is connected to an ignition device 21 composed of an ignition coil or the like. This spark plug 20
An in-cylinder pressure sensor 22 serving as an in-cylinder pressure detecting means, which is formed as a washer by sandwiching an annular piezoelectric body with electrodes, is attached to the mounting portion. The cylinder pressure sensor 22 is the combustion chamber 1
When the pressure inside the cylinder 3 (cylinder pressure) is received, the mechanical displacement due to this pressure is converted into an electric signal and output to the control unit 30 described later.

A swirl control valve 23 (hereinafter referred to as "SCV23") is rotatably provided at each branch portion of the intake manifold on the downstream side of the intake passage 14, and the SCV23 is swirl controlled via a link mechanism 24. It is connected to the actuator 25.
Then, the solenoid valve 26 for swirl control opens and closes, and the negative pressure introduced into the swirl control actuator 25 is supplied and cut off, whereby the SCV 23 rotates and opens and closes, and the swirl in the combustion chamber 13 Is variably controlled. Here, when the SCV 23 is closed, the swirl is strengthened, and when the SCV 23 is opened, the swirl is weakened.

Reference numeral 27 is a throttle sensor for detecting opening / closing of the throttle valve 19, 28 is a crank angle sensor for detecting a crank angle, and 29 is a water temperature sensor for detecting a cooling water temperature of the engine. Each of these sensors is an air conditioner (not shown). It is connected to the control unit 30 together with switches and the like.

The control unit 30 that electrically centrally manages the internal combustion engine includes a calculation unit including a CPU, a ROM,
9 to 14 is configured as a microcomputer system including a storage unit including a RAM and the like.
The map shown in is stored in advance. Further, an air flow meter 18, an in-cylinder pressure sensor 22, a crank angle sensor 28, etc. are connected to the input side of the control unit 30,
On its output side, an ignition device 21 and a fuel injection valve (not shown)
Etc. are connected.

Next, the relationship between the failure of the SCV 23 and the combustion period and the response to the SCV 23 failure will be described with reference to FIGS. 3 and 4.

First, FIG. 3 shows the SCV during lean combustion.
23 is a waveform diagram showing the relationship between the failure of No. 23 and the combustion period, etc., and during normal operation when the SCV 23 is normally closed and the swirl is strengthened, the cylinder pressure reaches a peak value from the crank angle at ignition. The combustion period BT1 required to reach the crank angle θ _Pmax at this time is obtained as shown in FIG. The combustion period BT1 is substantially uniquely determined according to the engine speed N and the basic injection amount T _P, and its characteristic is given to the control unit 30 in advance as a map.

Here, if the SCV 23 has an open failure and the SCV 23 does not close despite the lean combustion state, the swirl does not occur and the combustion speed becomes slow, as shown in FIG. 3 (b). As shown, the actual combustion period BT2
Becomes longer than the normal combustion period BT1. Therefore,
The open fault can be estimated from the comparison between the two. Then, when such an open failure is detected in the lean combustion region, the ignition timing is corrected to the advance side in this embodiment to avoid the deterioration of drivability. That is, as shown in FIG. 3C, the crank angle θ _Pmax when the in-cylinder pressure reaches the peak value
By advancing the ignition timing in the normal state that is initially set so as to match that in the normal state, the optimum operation can be performed under the open failure of the SCV 23.

On the other hand, FIG. 4 is a waveform diagram showing the relationship between the failure of the SCV 23 and the combustion period, etc. during operation near the stoichiometric air-fuel ratio, and during normal operation with the SCV 23 open, during lean combustion. Similarly, the combustion period BT3 required from the crank angle at the time of ignition to the crank angle θ _Pmax when the in-cylinder pressure reaches the peak value is almost uniquely determined from the rotation speed N and the basic injection amount T _P. It is determined as shown in FIG. 4A, and its characteristics are given in advance as a map. Then, when the SCV 23 has a closing failure and the SCV 23 does not open despite the operation in the vicinity of the stoichiometric air-fuel ratio, the swirl does not stop and the combustion speed becomes higher than that in the normal state. As shown in (b), the actual combustion period BT4 is shorter than the normal combustion period BT3.
Therefore, also in this case, the existence of the closed fault can be estimated by comparing the two. When such a closing failure is detected in the stoichiometric air-fuel ratio range, the ignition timing is retarded in this embodiment to prevent the deterioration of the operating condition. That is, as shown in FIG. 4 (c), if the ignition timing is retarded so that the crank angle θ _Pmax when the in-cylinder pressure reaches the peak value matches that under normal conditions, under the closing failure of the SCV 23, The operation can be optimized.

Next, the operation of the structure of this embodiment will be described in detail with reference to FIGS. First, FIGS. 5 and 6 show the main program. In step 1, the engine speed N and the basic injection amount T _P are detected from the signal from the crank angle sensor 28 or the like in order to detect the operating state of the internal combustion engine.
Is read, and in step 2, the rotation speed N and the basic injection amount T _P
Based on and, it is determined whether the internal combustion engine should be operated in a lean burn state (lean burn) or in the vicinity of the theoretical air-fuel ratio. If "YES" is determined in this step 2, it means that the engine should be operated in a lean burn state, so the routine moves to step 3 and the normal combustion period BT1 during lean burn is read from the map shown in FIG.

Then, in step 4, it is judged whether or not the open failure flag is "0", and in step 4, "YE
If it is determined to be "S", if the open failure flag is not set, that is, in the open failure determination routine described later, SCV23
Is a normal case in which it is not determined that the open failure has occurred, the routine proceeds to step 5, and ignition is performed according to the current rotational speed N and the basic injection amount T _P from the normal ignition timing map at the time of lean combustion shown in FIG. The timing SP1 is read out, and in step 6, the internal combustion engine is operated at this normal ignition timing SP1. On the other hand, when it is determined to be "NO" in Step 4, it means that the SCV 23 is open and is in a failure state. Therefore, the process proceeds to Step 7, and the ignition for failure at the time of lean combustion shown in FIG. From the timing map, the ignition timing SP2 that is set to the advance side so that the crank angle θ _Pmax indicating the in-cylinder pressure of the peak value becomes MBT is read out, and step 8
Then, by performing the ignition based on the ignition timing SP2, the combustion corresponding to the failure of the SCV 23 is realized.

Next, at step 9, in-cylinder pressure sensor 22
In step 10, the actual combustion period BT2 required from the ignition to the peak value of the in-cylinder pressure is calculated based on the signals of the in-cylinder pressure sensor 22 and the crank angle sensor 28. Then, it is determined whether or not the actual combustion period BT2 is longer than the combustion period BT1 in the normal operation read in step 3 by a predetermined ratio or more. Note that “α” in step 10 is a predetermined value of α> 1.

If "YES" is determined in this step 10, it is estimated that the SCV 23 has an open failure,
In the open failure determination routine in step 11, it is finally determined whether or not the SCV 23 is in failure, while in step 10, “N
When it is determined to be “O”, the actual combustion period BT2 and the previously determined normal combustion period BT1 are substantially equal to each other,
Since no failure has occurred, the process moves to step 12 to set the open failure flag to "0" and returns.

Next, an open failure determination routine for determining an open failure of the SCV 23 will be described with reference to FIG. First, in step 31, the actual combustion period BT2 obtained from the signal of the in-cylinder pressure sensor 22 is stored in BKUP, and in step 32, the fixed flag is set to "1" in order to keep the ignition timing and the fuel injection amount at the current values. set.

Then, in step 33, an open signal is output to the swirl control actuator 25 in order to open the SCV 23, in step 34, the signal from the cylinder pressure sensor 22 is read, and in step 35,
It is determined whether or not the latest combustion period BT detected by the signal of the in-cylinder pressure sensor 22 after the output of the open signal is shorter than the combustion period BKUP (= BT2) detected before the output of the open signal by a predetermined ratio or more. . Note that “γ” shown in step 35 is a predetermined value of 0 <γ <1.

If the SCV 23 does not have an open failure, that is, if the combustion period is delayed due to another cause although the SCV 23 is normally closed, the output is made in step 33. SCV2 by open signal
As a result of opening valve 3 and reducing the swirl, the combustion period BT becomes longer. On the other hand, when the SCV 23 has an open failure, the operation of the SCV 23 does not change even when the open signal is output, so that the combustion period BT does not significantly change. Therefore, when it is determined "YES" in step 35,
When there is no substantial change in the combustion period before and after the output of the open signal to the SCV 23, that is, when it can be determined that the SCV 23 has an open failure, the process proceeds to step 36 and the open failure flag is set to "1". On the other hand, when it is determined to be “NO” in the step 35, it means that the SCV 23 itself has no failure, so that the open failure flag is set to “0” in the step 37.

Then, in step 38, a close signal is output in order to restore the SCV 23 to the original state, and in step 39, the fixed flag is set to "0" in order to release the fixed ignition timing and fuel injection amount. And finish.

The above is the processing at the time of lean combustion, and next, when the determination at step 2 shown in FIG. 5 is "NO", that is, the processing when the engine should be operated near the stoichiometric air-fuel ratio. This will be described with reference to FIG.

First, at step 13, the normal combustion period BT3 in the vicinity of the stoichiometric air-fuel ratio is read from the map shown in FIG. 10, and at step 14, it is judged whether or not the close failure flag is "0". If "YES" is determined in this step 14, the SCV23
Since it has not been finally determined that the closing failure has occurred in step S15, the process proceeds to step 15 and the ignition timing corresponding to the current rotational speed N and the basic injection amount T _P is determined from the ignition timing map during normal operation shown in FIG. SP3 is read out, and in step 16, the engine is ignited based on the normal ignition timing SP3. On the other hand, if it is determined to be "NO" in step 14, it means that the SCV 23 has a closing failure, so the process proceeds to step 17, and from the closing failure ignition timing map in the state near the stoichiometric air-fuel ratio shown in FIG. Crank angle θ _Pmax is MBT
The ignition timing SP4 set to the retard angle side is read out, and in step 18, the ignition timing SP4 is controlled.

Then, in step 19, the in-cylinder pressure is read from the signal of the in-cylinder pressure sensor 22, and in step 20, the actual combustion period BT4 is calculated based on the signal of the in-cylinder pressure sensor 22 and the signal of the crank angle sensor 28. Then, it is determined whether or not the actual combustion period BT4 is shorter than the combustion period BT3 during normal operation by a predetermined ratio or more. Note that “β” shown in step 20 is a predetermined value of 0 <β <1.
If "YES" is determined in this step 20, SC
Since it can be estimated that V23 has a closed failure, the final determination is made in the closed failure determination routine as to whether or not the SCV23 is a failure, and when "NO" is determined, the actual combustion period B
Since T4 and the previously determined normal combustion period BT3 are substantially equal to each other and no failure has occurred, the process proceeds to step 22 and the closed failure flag is set to "0".
To return.

Next, a closing failure judgment routine for finally judging the closing failure of the SCV 23 will be described with reference to FIG. First, in step 41, the actual combustion period BT4 obtained from the signal of the in-cylinder pressure sensor 22 is stored in BKUP, and in step 42, the fixed flag is set to "1" in order to keep the ignition timing and the fuel injection amount at the current values. Set.

Then, in step 43, a close signal is output to close the SCV 23, and in step 44,
The signal from the in-cylinder pressure sensor 22 is read, and in step 45, the latest combustion period BT detected by the signal of the in-cylinder pressure sensor 22 after this closing signal is output is the combustion period BKUP (= BT4 detected before the closing signal is output. ) Or less than a predetermined ratio. Note that “δ” in step 45 is a predetermined value of 0 <δ <1.

Here, if the SCV 23 does not have a closing failure, that is, if the combustion period is shortened due to other causes although the SCV 23 is normally opened, the output is made in step 43. SCV2 due to closed signal
Since 3 is closed and the swirl is strengthened, the combustion period BT is further shortened. On the other hand, when the SCV 23 has a closing failure, the operation of the SCV 23 does not change even when the closing signal is output, and therefore the combustion period BT does not greatly change. Therefore, when it is determined "YES" in step 45,
Since there is no substantial change in the combustion period before and after the output of the closing signal to the SCV 23, that is, when the closing failure has occurred in the SCV 23, the routine proceeds to step 46, and the closing failure flag is set to "1". On the other hand, if it is determined to be "NO" in step 45, it means that the SCV 23 itself has not failed, and therefore, the open failure flag is set to "0" in step 47.

Then, in step 48, an open signal is output to restore the SCV 23 to the original state, and in step 49, the fixed flag is set to "0" to release the fixed ignition timing and fuel injection amount. And finish.

As described above, according to this embodiment, the actual combustion period BT2 (BT
4) is detected, and the combustion period BT1 in the normal state is determined almost uniquely from the operating state of the engine of the rotational speed N and the basic injection amount T _P.
By comparing with (BT3), it is determined whether or not there is a possibility of failure in the SCV 23, and if there is a possibility of failure, an open signal and a closed signal are output to the SCV 23, and a signal before and after this output signal is output. Since the SCV23 failure is finally judged from the fluctuation of the combustion period and the ignition timing is adjusted so that the crank angle θ _Pmax when the in-cylinder pressure reaches the peak value is set to MBT, only the operation of the SCV23 is performed. It is possible to reliably detect the failure of the SCV 23 without providing a special sensor that detects, and to greatly improve the reliability of the internal combustion engine without complicating the mechanical structure. Further, the in-cylinder pressure sensor 2 using a piezoelectric body that outputs an electric signal according to stress
Since the failure detection is performed by using the signal of No. 2, there is no mechanical moving part, and there is no room for mechanical failure such as contact failure of contacts, welding, disengagement of the opening / closing detection sensor and SCV, and the like. Failure detection accuracy is greatly improved.

It should be noted that in the first embodiment, it is described that the failure of the SCV 23 is estimated by comparing the combustion periods, and then the failure of the SCV 23 is finally determined by the open failure determination routine and the closed failure determination routine. Without being limited to this, the SCV 23 may be detected to have a failure only by comparing the combustion periods.

Further, in the above embodiment, the combustion period BT is exemplified as the combustion parameter indicating the combustion state, but instead of this, for example, the indicated mean effective pressure or the like may be used.

Further, in the above embodiment, when the SCV 23 fails, the ignition timing is switched to the ignition timing map set to the advance side and the ignition timing map set to the retard side,
Although the combustion state is optimized under the failure of the SCV 23, the present invention is not limited to this. For example, the fuel injection amount correction value maps corresponding to the open failure and the closed failure of the SCV 23 are provided, and the failure of the SCV 23 occurs. The combustion state may be improved by sometimes changing the map to correct the fuel injection amount, or both the ignition timing and the fuel injection amount may be corrected.

[0038]

As described in detail above, according to the failure detecting device for an internal combustion engine according to the present invention, the actual combustion state parameter detected by the combustion state detecting means by using the signal of the in-cylinder pressure detecting means, and the operation The failure determination means determines the failure of the swirl control valve by comparing the normal combustion status parameter detected by the normal combustion status setting means based on the signal of the status detection means, and the operation status switching means controls the failure. Can be switched to. As a result, it is possible to reliably detect a failure of the swirl control valve without providing a special sensor for detecting the operation of the swirl control valve, prevent mechanical failure from occurring, and improve reliability. be able to.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing a configuration of a failure detection device according to the present invention.

FIG. 2 is an explanatory diagram of a configuration of a failure detection device according to an embodiment of the present invention.

FIG. 3 is a waveform chart showing the relationship between SCV failure and combustion period during lean combustion.

FIG. 4 is a waveform diagram showing the relationship between SCV failure and combustion period during combustion near the stoichiometric air-fuel ratio.

FIG. 5 is a flowchart showing control of ignition timing and the like during lean combustion.

FIG. 6 is a flow chart showing control of ignition timing and the like near the stoichiometric air-fuel ratio.

FIG. 7 is a flowchart showing an open failure determination routine.

FIG. 8 is a flowchart showing a closed failure determination routine.

FIG. 9 is an explanatory diagram of a map in which a combustion period during normal operation in a lean burn state is stored.

FIG. 10 is an explanatory diagram of a map in which a combustion period during normal operation in a combustion state near the stoichiometric air-fuel ratio is stored.

FIG. 11 is an explanatory diagram of a map in which ignition timings in normal operation in a lean burn state are stored.

FIG. 12 is an explanatory diagram of a map in which the ignition timing at the time of open failure in the lean burn state is stored.

FIG. 13 is an explanatory diagram of a map in which ignition timings in normal operation in a combustion state near the stoichiometric air-fuel ratio are stored.

FIG. 14 is an explanatory diagram of a map in which the ignition timing at the time of a closing failure in a combustion state near the stoichiometric air-fuel ratio is stored.

[Explanation of symbols]

 1 ... In-cylinder pressure detecting means 2 ... Combustion state detecting means 3 ... Operating state detecting means 4 ... Normal combustion state setting means 5 ... Failure determining means 6 ... Operating state switching means 11 ... Cylinder 22 ... In-cylinder pressure sensor 23 ... Swirl control valve (SCV) 28 ... Crank angle sensor 30 ... Control unit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location F02D 45/00 368 T

Claims (1)

[Claims] 1. An in-cylinder pressure detecting means for detecting an in-cylinder pressure of an internal combustion engine; a combustion state detecting means for detecting a combustion state parameter indicating a combustion state based on a detection signal of the in-cylinder pressure detecting means; An operating state detecting means for detecting an operating state of the engine, a normal combustion state setting means for setting a normal combustion state parameter based on a detection signal of the operating state detecting means, and a combustion state parameter detected by the combustion state detecting means. A failure determination means for determining whether or not the swirl control valve of the internal combustion engine has failed by comparing the normal combustion state parameter set by the normal combustion state setting means with the normal combustion state parameter; and the failure determination means for swirl control. An internal combustion engine failure detection system comprising: an operating state switching means for switching to a predetermined failure control when it is determined that a valve has failed. Output device.