JPH086623B2 - Engine failure detection device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an engine failure detection device for an automobile or the like, and more particularly to an engine failure detection device for determining and detecting an abnormal location of an electronically controlled engine.

(Prior Art) In recent years, demands for automobile engines have become more sophisticated, and there is a tendency to achieve high levels of conflicting issues such as reduction of exhaust gas, high output, and low fuel consumption. Air-fuel ratio feedback control is performed to meet these requirements. Also, with the sophistication of electronic engine control, ensuring safety is an important issue. For example, all sensors and injectors installed in the engine intake / exhaust system are exposed to harsh environments of high temperature and high pressure. The failure detection function for the parts below helps ensure safety during operation.

A conventional engine failure detection device of this type is disclosed in, for example, JP-A-58-20539. In this device, for the disconnection or short circuit failure of the signal line of the air flow sensor and the injector arranged in the intake passage of the engine, the signal state is detected by the control unit to which the signal line of the air flow sensor and the injector are connected, A warning is given to the driver and maintenance personnel about the failure of the air flow sensor and injector.

(Problems to be Solved by the Invention) However, in such a conventional engine failure detection device, a disconnection and a short circuit failure of a signal line of an air flow sensor or an injector are detected only by respective signal states. Because of the configuration, it is possible to promptly detect an abnormal point and issue an alarm for control failure and deterioration of drivability due to aging deterioration of the air flow sensor and injector other than disconnection and short circuit failure. There wasn't. In addition, it is difficult for not only the driver but also the maintenance person to determine the abnormal portion with respect to such an abnormality. Therefore, improvements are desired in these points.

(Object of the Invention) Therefore, the present invention detects the oxygen concentration in the exhaust gas to determine the air-fuel ratio state, and by determining the detection output of the intake system sensor from this determination result, the injector, the air flow sensor, or the throttle valve opening. Accurately detect and detect abnormality in the sensor
The purpose is to improve engine safety.

(Means for Solving the Problems) In order to achieve the above object, the engine failure detection device according to the present invention has an intake air amount detection means a for detecting the intake air amount of the engine as shown in the basic conceptual diagram of FIG. A rotational speed detecting means b for detecting the engine speed, an opening degree detecting means c for detecting the opening degree of the throttle valve, an air-fuel ratio detecting means d for detecting the oxygen concentration in the exhaust gas, and an air-fuel ratio detecting means. Discriminating means e for calculating an air-fuel ratio correction coefficient for correcting the air-fuel ratio to a target air-fuel ratio based on the output of d, and judging whether the air-fuel ratio correction coefficient is within a first predetermined range, and a throttle valve. Reference value setting means f for setting the reference air amount based on the opening degree and the engine speed.
A difference value calculating means g for calculating an intake difference value by comparing the output of the intake amount detecting means a with the reference intake amount; and the intake difference value when the air-fuel ratio correction coefficient is within a first predetermined range. Second
If the intake difference value is within the second predetermined range when the air-fuel ratio correction coefficient is out of the first predetermined range, the fuel is judged to be abnormal if the opening degree detection means c is not within the predetermined range. Determination means h for performing at least one of a second determination for determining that the supply system actuator is abnormal, and a third determination for determining that the intake air amount detecting means a is abnormal if the supply system actuator is not within the second predetermined range. , Are provided.

(Operation) In the present invention, the first predetermined range for determining whether the air-fuel ratio correction coefficient is normal or abnormal and the second predetermined range for determining the intake difference value based on the first predetermined range are set, and When the air-fuel ratio correction coefficient is within the first predetermined range, the intake difference value is the second
If it is not within the predetermined range, the first determination is that the throttle valve opening sensor is abnormal, and if the intake-air difference value is within the second predetermined range when the air-fuel ratio correction coefficient is out of the first predetermined range, the injector. By performing at least one of the second determination of determining that the airflow sensor is abnormal and the second determination of determining that the airflow sensor is abnormal if the second determination range is not satisfied,
Abnormalities due to deterioration over time of the throttle valve opening sensor, the injector or the air flow sensor are accurately determined and detected.

Therefore, the safety of the engine during operation is improved and the burden of maintenance work on the driver and the maintenance person after an abnormality occurs is reduced.

(Example) Hereinafter, it demonstrates based on the drawing of this invention.

 Second and third embodiments are diagrams showing a first embodiment of the present invention.

First, the configuration will be described. In FIG. 2, reference numeral 1 denotes an engine, intake air is supplied to a cylinder from an air cleaner 2 through an intake passage 3 as indicated by an arrow in the drawing, and fuel is injected by an injector (fuel supply system actuator) 4 based on an injection signal Si. Is jetted. The cylinder is equipped with a spark plug 5, and a high voltage pulse Hp from the ignition coil 7 is supplied to the spark plug 5 via a distributor 6.
Is supplied. The ignition coil 7 generates a high-pressure pulse Hp based on the ignition signal Sp and supplies the high-pressure pulse Hp to the spark plug 5, and the mixture in the cylinder is ignited and exploded due to the discharge to the high-pressure pulse Hp, and becomes exhaust gas from the exhaust passage 8. It is discharged through the catalytic converter 9 and the muffler 10 sequentially.

Intake air amount Qa is an air flow sensor (intake air amount detection means)
11 and is controlled by interlocking throttle valves 12a and 12b in the separation passages 3a and 3b of the intake passage 3. The opening Cv of the throttle valve 12a is detected by a throttle valve opening sensor (opening detection means) 13, and the air flow rate bypassing the throttle valves 12a and 12b is AAC valve 1
It is adjusted by 4, which controls the idle speed. The AAC valve 14 is driven based on the auxiliary air amount control signal S _A. A variable intake control valve 15 is provided on the cylinder side separation wall of the separation passages 3a and 3b. The variable intake control valve 15 is adjusted by a variable intake control solenoid valve 16, a vacuum tank 17 and a one-way valve 18. The intake amount in the high speed range is controlled. The variable intake control solenoid valve 16 is driven based on the variable intake control signal S _R. In addition, 19 is a turbocharger, which aims to increase the intake efficiency and increase the output of the engine 1. Swing valve control 20 adjusts the elapsed pressure of turbocharger 19.

The temperature Tw of the cooling water flowing through the water jacket of the engine 1 is detected by the water temperature sensor 21. The oxygen concentration in the exhaust gas is detected by an oxygen sensor (air-fuel ratio detecting means) 22, and the oxygen sensor 22 outputs its detection signal Vs. Reference numeral 23 is a knock sensor, and 24 is an exhaust temperature sensor. The exhaust temperature sensor 24 is connected to the switching module 25,
The switching module 25 turns on the exhaust temperature warning lamp 26 based on the detection output of the exhaust temperature sensor 24. Further, a crank angle sensor (rotation speed detecting means) 27 is built in the distributor 6, and the crank angle sensor 27 detects the rotation speed of the engine 1 and outputs a rotation signal N _θ . The neutral position Nc of the transmission 28 is detected by the neutral switch 29, and the vehicle speed Ss is detected by the vehicle speed sensor 30. In addition, 31 is a canister and 32 is a fuel pump.

The signals from the sensors 11, 13, 21, 22, 23, 29, 30 and key switches (not shown) and the battery are input to the control unit 35, and the control unit 35
Calculates the air-fuel ratio, the engine speed, etc. based on these sensor information, and drives the injector 4, the ignition coil 7, the AAC valve 14, the variable intake control solenoid valve 16 and the fuel pump 32 according to the result. The signals Si, Sp, S _A , S _R and S _F are output to optimally control the operating state of the engine 1. Further, the control unit 35 detects the failure of the engine 1 based on the angle signals Qa, Cv, Vs and N _θ from the air flow sensor 11, the throttle valve opening sensor 13, the oxygen sensor 22 and the crank angle sensor 27. That is, the control unit 35 has functions as a discriminating means, a reference value setting means, a difference value calculating means and a discriminating means, and is constituted by a microcomputer or the like. Reference numerals 36 and 37 are monitor check lamps, which give an alarm to a driver and a maintenance person based on a failure detection signal of the control unit 35.

 Next, the operation will be described.

FIG. 3 is a flow chart showing a program for detecting a failure of the engine. This program is based on the change in the air-fuel ratio during operation and the injector 4 and the air flow sensor.
It detects 11 abnormalities. First, at P ₁ , the engine speed N is calculated based on the rotation signal N _θ of the crank angle sensor 27, and at P ₂ , the intake air amount Qa is read. Then, read the throttle valve opening degree Cv at P _3, and calculates an air-fuel ratio correction coefficient α for correcting the air-fuel ratio based on the output Vs of the oxygen sensor 22 in the P _4. The target air-fuel ratio is successively feedback-corrected based on the air-fuel ratio correction coefficient α, and the air-fuel ratio of the engine 1 is controlled to the target air-fuel ratio. And have the following, P _5, alpha at P ₆ it is determined whether or not a predetermined normal, the range of the abnormality judgment (first predetermined range) in (Arufamin～arufamax). When αmin ≤ α ≤ αmax, it is determined that the air-fuel ratio correction coefficient α is normal, and this routine is terminated. On the other hand, when α <αmin or α> αmax, the air-fuel ratio correction coefficient α is abnormal. proceed to P ₇ to determine that there is. The upper limit value αmax and the lower limit value αmin for discriminating the air-fuel ratio correction coefficient α are stored in advance in the ROM or the like in the control unit 35, and the discrimination range is set on the assumption that the air-fuel ratio control is normal. To be done. Therefore, if the air-fuel ratio correction coefficient α is out of the determination range, it means that the injector or the air flow sensor is abnormal because the fuel amount or the intake air amount is abnormal. It should be noted that this discrimination range is set in advance by experiments or the like. At P ₇ , the reference intake air amount Qa when α is normal from the rotational speed N and throttle valve opening Cv
s is calculated, and at P ₈ , an intake difference value ΔQa between the reference intake air amount Qas and the intake air amount Qa is calculated by the following equation.

ΔQa = Qa−Qas ... Then, at P ₉ and P _10, it is determined whether ΔQa is within the range (second predetermined range) of the intake air amounts Qmin and Qmax corresponding to the αmin and αmax, respectively. From the result of this determination, it is determined whether the injector 4 and the air flow sensor 11 are abnormal. That is, when Qmin <ΔQa <Qmax, it is determined that the intake air amount Qa is normal, while when ΔQa <Qmin or ΔQa> Qmax, it is determined that the intake air amount Qa is abnormal.

Therefore, when Qmin <.DELTA.Qa <of Qmax, the intake air amount Qa is normal, since the air-fuel ratio correction coefficient α is abnormal cause of this case depends insufficient and rich fuel quantity, the abnormality of the injector 4 at P ₁₁ Give an alarm. On the other hand, when Δa <Qmin or ΔQa> Qmax, the intake air amount Qa is insufficient and excessive, so an abnormal alarm of the air flow sensor 11 is issued at P ₁₂ . This alarm is continuously issued until the abnormal part is repaired, and after the repair, the alarm is canceled. This program is repeatedly executed during operation. The intake air amounts Qmin and Qmax are also stored in advance in the ROM in the control unit 35, like αmin and αmax.

As described above, in the first embodiment, the failure location of the engine 1 when the air-fuel ratio correction coefficient α during operation deviates from the predetermined determination range is accurately determined with almost no time delay and an alarm is issued. In addition to ensuring the safety of the engine 1 during operation, it also reduces the burden of maintenance work on the driver and maintenance personnel after an abnormality occurs.

In addition, in these series of programs, the injector 4 and the air flow sensor 11 are based on a plurality of sensor information.
Since the failure detection is performed, unlike the prior art, in addition to the failure such as the disconnection or the short circuit of the injector 4 and the air flow sensor 11, the abnormality due to the deterioration over time can be surely detected. This improves the reliability of the control system.

FIG. 4 is a flow chart of a program showing a second embodiment of the present invention. In this embodiment, an abnormality of the throttle valve opening sensor 13 when the air-fuel ratio correction coefficient α is normal is detected. In this program, steps that perform the same processing as the program of FIG. 3 in the first embodiment are given the same numbers and their explanations are omitted, and different steps are given step numbers surrounded by a circle and their contents Will be explained. The Te P _21, P ₂₂ to determine whether the air-fuel ratio correction coefficient alpha is within a predetermined determination range (αmin~αmax), the process proceeds to P ₇ when .alpha.min <alpha of <.alpha.max, one, alpha> .alpha.max If α <αmin, the current routine is terminated. When the air-fuel ratio correction coefficient α is normal P _9,
At P ₁₀ , it is determined whether the intake difference value ΔQa between the reference intake air amount Qas and the intake air amount Qa is within the intake air amount Qmin and Qmax ranges corresponding to the αmin and αmax, respectively, as in the first embodiment. An abnormality of the throttle valve opening sensor 13 is determined from this determination result. That is, ΔQa> Qmax or ΔQa <Qmin
When, the fuel amount in the mixture and the intake air amount Qa are normal,
From the relationship of ΔQa = Qa−Qas in the above equation, the reference intake air amount Qas
Turns out to be abnormal. This is the reference intake air amount Qas
This is because the detection signal Cv of the throttle valve opening sensor 13, which is a calculation element of, is abnormal, and it can be determined that the throttle valve opening sensor 13 is abnormal. Then, issues an abnormality alarm throttle valve opening sensor 13 at P _23. This alarm is continuously issued until the throttle valve opening sensor 13 is repaired, and the alarm is canceled after the repair.

On the other hand, when Qmin <ΔQa <Qmax, it is determined that both the reference intake air amount Qas and the intake air amount Qa are normal, and this routine is ended. This program is repeatedly executed during operation. As described above, in the present embodiment, unlike the first embodiment, it is possible to detect an abnormality in the throttle valve opening sensor 13 when the air-fuel ratio correction coefficient α is normal, and further improve the safety during operation. .

If the first and second embodiments are used together, at least three of the injector, the air flow sensor, and the throttle valve opening sensor will be used.
The failure and abnormality of one component can be accurately detected and detected, which further improves the safety during operation.

(Effect) According to the present invention, the oxygen concentration in the exhaust gas is detected, the air-fuel ratio state is determined, and whether the detection output of the intake system sensor corresponds to the air-fuel ratio state based on the determination result. Since it is determined whether or not the abnormality of the injector, the air flow sensor, or the throttle valve opening sensor can be accurately determined and detected, the safety of the engine during operation can be improved. In addition, the burden of maintenance work on the driver and mechanic after the occurrence of an abnormality is reduced.

[Brief description of drawings]

FIG. 1 is a basic conceptual diagram of the present invention, FIGS. 2 and 3 are diagrams showing a first embodiment of an engine failure detection device according to the present invention, FIG. 2 is an overall configuration diagram thereof, and FIG. FIG. 4 is a flow chart showing a program for detecting abnormality of the injector and the air flow sensor, and FIG. 4 is a flow chart showing program for detecting abnormality of the throttle valve opening sensor according to the second embodiment of the present invention. 1 ... Engine, 4 ... Injector (fuel supply actuator), 11 ... Air flow sensor (intake amount detection means), 13 ... Throttle valve opening sensor (opening detection means), 22 ... Oxygen sensor (air-fuel ratio) 27 ... Crank angle sensor (rotation speed detecting means), 35 ... Control unit (discriminating means, reference value setting means, difference value computing means, determining means).

Claims (1)

[Claims] Claims: 1. A) intake air amount detecting means for detecting the intake air amount of the engine; b) rotational speed detecting means for detecting the rotational speed of the engine; and c) opening degree detecting means for detecting the opening of the throttle valve. And d) air-fuel ratio detecting means for detecting the oxygen concentration in the exhaust gas, and e) calculating an air-fuel ratio correction coefficient for correcting the air-fuel ratio to the target air-fuel ratio on the basis of the output of the air-fuel ratio detecting means, and correcting the air-fuel ratio. Determination means for determining whether or not the coefficient is within a first predetermined range; f) reference value setting means for setting a reference air amount based on the throttle valve opening and engine speed; g) intake air amount Difference value calculating means for calculating an intake difference value by comparing the output of the detecting means with the reference intake air amount; and h) when the air-fuel ratio correction coefficient is within a first predetermined range, the intake difference value is a second predetermined value. If it is not within the range, the first determination that the opening detection means is abnormal and the air-fuel ratio correction coefficient are When the intake difference value is out of the predetermined range of 1, the second determination is made that the fuel supply system actuator is abnormal if the intake difference value is in the second predetermined range, and the intake amount detecting means is abnormal if it is not in the second predetermined range. A failure determination device for an engine, comprising: a third determination to determine that the determination is made, and a determination unit that performs at least one determination.