JPH0539744A - Failure detecting device and method for fuel injection device - Google Patents

Abstract

PURPOSE:To provide the failure detecting device for a fuel injection device, which can detect failures regardless of operating conditions and also can identify any cylinder having a failed injector. CONSTITUTION:There are provided a plural number of cylinders driving an internal combustion engine 1 and injectors 5a through 5d injecting fuel F to inlet air passages 2a through 2d for the respective cylinders. There are also provided a fuel transfer means 7 supplying pressurized fuel F to the injectors 5a through 5d and a fuel pressure detecting means 10 detecting the pressure P of fuel F. Furthermore, there are provided a fuel injection quantity operating means 20 operating the quantity of fuel injection by each injector 5a through 5d based on the operating conditions of the internal combustion engine 1, and a failure judging means 20 judging the failure of each injector 5a through 5d based on the ripple value of fuel pressure when fuel is injected. When the ripple value of fuel pressure is smaller than a specified one, it is judged that each injector 5a through 5d of the cylinders intended for detection, has failed. By this constitution, failures for any operation can be detected regardless of the temperature of exhaust gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a failure detecting device and method for a fuel injection device, which can determine a failure of an injector irrespective of an operating condition.

[0002]

2. Description of the Related Art Generally, in an internal combustion engine driven by a plurality of cylinders, an injector of a fuel injection device is opened to inject fuel and inject fuel at a predetermined timing of each cylinder to perform ignition control. .. Normally, the fuel injection amount is controlled by changing the opening time of the injector according to the operating state (load etc.). Further, the rich state or lean state of the air-fuel ratio is determined according to the oxygen concentration in the exhaust gas, and the fuel injection amount by the injector is feedback-controlled so that the air-fuel ratio becomes optimum.

However, if carbon or the like adheres to the nozzle portion of the injector to cause clogging or foreign matter enters the seal portion inside the injector to cause a fuel leak or the like, the injector, that is, the fuel injection device will malfunction, resulting in exhaust gas. Emissions in gas deteriorate and fuel ratio also deteriorates. Therefore, there is a demand for a failure detection device for detecting a failure of a fuel injection device including an injector and warning the driver.

Conventionally, as a device and method for detecting a failure of a fuel injection device of this type, as disclosed in, for example, Japanese Patent Laid-Open No. 63-314344, the output value of an oxygen sensor is set during a set period shorter than a normal period. There is one that determines the failure of the injector when it is turned over. However, the operating characteristics of oxygen sensors are temperature-dependent, for example, when the exhaust gas temperature is 300 ° C.
It will not be activated unless the operating conditions shown above are reached. Further, since it takes time from the operation of the injector to the detection of the exhaust gas temperature, the cylinder to which the failed injector belongs cannot be specified.

[0005]

Since the conventional fuel injection device failure detection device and method use the output of the oxygen sensor as described above, the specific operation in which the exhaust gas exceeds the activation temperature of the oxygen sensor. There is a problem that failure detection is not possible except in the state and there is a time lag in the detection of exhaust gas temperature, so that the failure injector cannot be specified.

The present invention has been made to solve the above problems, and is capable of detecting a failure irrespective of the operating state and capable of specifying the cylinder to which the failed injector belongs. And to obtain a method.

[0007]

A failure detection device for a fuel injection device according to the present invention includes a plurality of cylinders for driving an internal combustion engine, an injector for injecting fuel into an intake passage for each cylinder, and an injector pressurized. Fuel supply means for supplying fuel, fuel pressure detection means for detecting fuel pressure, fuel injection amount calculation means for calculating the fuel injection amount by the injector based on the operating state of the internal combustion engine, and fuel during fuel injection And a failure determination means for determining a failure of the injector based on the ripple value of pressure.

Further, in the method of detecting a failure of a fuel injection device according to the present invention, a step of detecting the maximum value and the minimum value of the fuel pressure for each reference position corresponding to a predetermined crank angle of each cylinder, and the maximum value and the minimum value. And a reference maximum value and a reference minimum value according to the operating state of the internal combustion engine, respectively, and when the maximum value is less than the reference maximum value and the minimum value is less than the reference minimum value And determining that the injector to which it belongs is out of order.

[0009]

According to the present invention, the fuel pressure fluctuation (ripple) at the time of fuel injection is detected, and if the ripple value is smaller than the set value, it is determined that the injector of the cylinder to be detected has a failure, regardless of the exhaust gas temperature. Detects failures in all operating conditions.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a failure detection device for a fuel injection device according to an embodiment of the present invention, where 1 is a plurality (for example,
# 1 to # 4) internal combustion engine driven by cylinders (not shown), 2 is an intake manifold provided on the intake side of the internal combustion engine 1, and 2a to 2d are inside the intake manifold 2 corresponding to each cylinder. The intake passage 3 provided is a throttle for adjusting the amount of air supplied to the intake manifold 2 in accordance with the load of the internal combustion engine 1, and 4 is the intake manifold 2.
Air flow sensor for detecting air intake A to the
An injector 5d is individually arranged in the intake passages 2a to 2d for each cylinder and injects fuel.

Reference numeral 6 is a fuel tank for storing the fuel F, 7 is a fuel transportation means or fuel pump for pressurizing the fuel F in the fuel tank 6 and supplying it to the injectors 5a to 5d, and 8 is a parallel arrangement of the injectors 5a to 5d. A delivery pipe that supports and supplies pressurized fuel, 9 is a pressure regulator that returns excess pressurized fuel to the fuel tank 6 to adjust the fuel pressure P in the delivery pipe 8, and 10 is fuel in the delivery pipe 8. A fuel pressure detecting means for detecting the pressure P, that is, a pressure sensor, 11 is an exhaust manifold that collectively discharges exhaust gas from the internal combustion engine 1, and 12 is a cylinder corresponding to a crank angle and indicating a rotational speed of the internal combustion engine 1. Identification signal SC and reference position signal ST
Is a rotation sensor that generates

Reference numeral 20 denotes the internal combustion engine 1 based on the air intake amount A, the fuel pressure P, the cylinder identification signal SC, the reference position signal ST and the like.
Is an ECU (electronic control unit) that controls ignition of the
Fuel injection amount calculation means for calculating the fuel injection amount by each of the injectors 5a to 5d based on the operating state of the internal combustion engine 1 obtained from the air intake amount A and the rotational speed, and based on the ripple value of the fuel pressure P at the time of fuel injection. Injectors 5a to 5d including failure determining means for determining a failure of the injectors 5a to 5d.
Control signal C is generated.

FIG. 2 is a block diagram showing a configuration example of the ECU 20, 21 is an input interface for taking in the cylinder identification signal SC and the reference position signal ST from the rotation sensor 12, and 22 is air intake from the air flow sensor 4. An input interface for taking in the quantity A and the fuel pressure P from the pressure sensor 10, and 23 is a battery when the key switch 24 is closed.
A power supply circuit fed from 25, 26 is an output interface for outputting the control signal C from the output terminal 27, 30 is a microcomputer (microcomputer) connected to the input interfaces 21, 22, the power supply circuit 23 and the output interface 26. is there.

The microcomputer 30 includes a CPU 31 for performing various calculations and determinations, a RAM 32 and a ROM 33 belonging to the CPU 31.
, A counter 34 for counting the number of occurrences of the cylinder identification signal SC and the reference position signal ST, a timer 35 for detecting the passage of a predetermined time, a fuel pressure P and air intake inputted via the input interface 22. An AD converter 36 for converting the quantity A into a digital signal, an output port 37 for outputting a control signal C and the like via the output interface 26, and a CPU 31.
And a bus 38 connecting the elements 32 to 37.

FIG. 3 shows a cylinder identification signal SC and a reference position signal S.
FIG. 5 is a waveform diagram showing T, injection timings of injectors 5a to 5d, and fuel pressure P, respectively, and a reference position signal ST is
The rising is set to correspond to B75 ° (the crank angle position 75 ° before the top dead center TDC), and the falling is set to correspond to B5 ° (corresponding to the ignition timing). Further, the pulse width of the cylinder identification signal SC is determined by the specific cylinder (for example, # 1 cylinder).
The reference positions B75 ° and B5 ° are included.

Further, the opening of the injectors 5a to 5d corresponding to the # 1, # 3, # 4 and # 2 cylinders, that is, the fuel injection, is performed immediately after the reference position B75 ° and before the reference position B5 °. Be seen. Further, the fluctuation (ripple) of the fuel pressure P occurs immediately after the fuel injection, and at the reference position B75 °, the fuel pressure P
The maximum value P _MAX and the minimum value P _MIN of

Next, with reference to the waveform diagram of FIG. 3 and the flow charts of FIGS. 4 to 7, the operation of the embodiment of the failure detecting device for the fuel injection device according to the present invention shown in FIGS. 1 and 2 will be described. To do. First, when the key switch 24 is closed, the microcomputer 30 in the ECU 20 operates to operate the internal combustion engine 1 based on the air intake amount A corresponding to the opening of the throttle 3, the cylinder identification signal SC, and the reference position signal ST. In addition, the control target cylinder and the like are determined. As a result, the microcomputer 30 generates the control signal C in accordance with the operating state, injects fuel into each of the cylinders # 1 to # 4 at the timing immediately after the reference position B75 °, and the reference position B5 ° around. Ignition control is performed at the timing.

At this time, the delivery pipe 8 is supplied with high-pressure fuel F from the fuel tank 6 via the fuel pump 7, and the fuel pressure P in the delivery pipe 8 is adjusted to a predetermined pressure by the pressure regulator 9. Since it is maintained, the fuel injection amount is determined by the opening time of the injectors 5a to 5d based on the control signal C. Therefore, the microcomputer 30 in the ECU 20
Is calculated based on the charging efficiency K _F (∝A / R) of the fuel F obtained from the rotational speed R of the internal combustion engine 1 and the air intake amount A, and the fuel injection amount is calculated so that the air-fuel ratio becomes the optimum value. Injector
A control signal C that determines the opening time of 5a to 5d is generated.

Further, the ECU 20 follows the main routine of FIG. 4 and initializes the internal combustion engine at the same time it is turned on.
Is performed (step S1), and it is constantly determined whether or not the error flags of all the cylinders corresponding to the injectors 5a to 5d are reset (step S2). If the error flag is reset, all of the injectors 5a to 5d are normal, but if the error flag is set, it is determined to be abnormal.
(Step S3), an alarm is generated by turning on an abnormal lamp (Step S4). As a result, the driver can replace or repair the injector of the cylinder for which the abnormality is determined.

Below, the failure detection operation of the injectors 5a-5d
(Error flag setting operation) will be specifically described. First, the microcomputer 30 takes in the fuel pressure P from the pressure sensor 10 at regular intervals based on the timer 35, and according to the timer interrupt routine of FIG. 5, the maximum value P _MAX and the minimum value P
Always update _MIN .

That is, it is judged whether or not the detected fuel pressure P is larger than the current maximum value P _MAX (step S11),
If P> P _MAX , the fuel pressure P is set to the maximum value P _MAX (step S12). If P ≦ P _MAX , it is determined whether or not the fuel pressure P is smaller than the present minimum value P _MAX (step S13). If P <P _MIN , the fuel pressure P is set to the minimum value P _MIN . Yes (step S14). As a result, the maximum value P _MAX and the minimum value P _MIN are clipped in real time.

On the other hand, the microcomputer 30 in the ECU 20 causes the reference position signal ST to rise (B75 °) and fall (B5 °).
6) and 7), the interrupt routines of FIG. 6 and FIG. 7 are repeatedly executed.

That is, the interrupt routine of the reference position B 75 °
In FIG. 6, first, the fuel injection cylinder is identified based on the cylinder identification signal SC and the reference position signal ST (step S21). Further, the maximum value P _MAX and the minimum value P _MIN are initialized to 0 and a predetermined value which is large to some extent (step S2).
2). As a result, the maximum value P _MAX and the minimum value P _MIN are shown in FIG.
As described above, the fuel pressure P periodically detected is sequentially updated.

Next, the fuel injection amount is calculated according to the operating state (step S23), and the control signal C is further generated to inject the fuel by opening the injectors 5a to 5d so as to match the calculated value. Yes (step S24).

In the interrupt routine for the reference position B5 ° (FIG. 7), first, the engine speed R is calculated based on the cylinder identification signal SC and the reference position signal ST (step S31). Then, it is determined whether fuel injection is in progress (step S
32), if fuel injection is not in progress, the maximum value P _{MAX of the} detected fuel pressure (obtained by the timer interrupt routine of FIG. 5)
Is larger than the reference maximum value XP _MAX (step S33).

In step S33, P _MAX > XP _MAX
If it is judged that the minimum value P of the detected fuel pressure
_It is determined whether _{MIN is} smaller than the reference minimum value P _MIN (step S34). If it is determined that P _MIN <XP _MIN , the reference count value XDCNT is set in the abnormality determination counter DCNT of the fuel injection cylinder (step S35).

Reference maximum value XP _MAX and reference minimum value XP _MIN
Is drawn from, for example, a data map according to the operating state based on the air intake amount A, the engine speed R, and the like.
Also, a counter DCN for providing redundancy in abnormality determination
T is installed for each cylinder, and the reference count value XDCNT set in this counter is set to an arbitrary value as necessary.

On the other hand, if it is determined in step S32 that the fuel is being injected, the fuel pressure P is fluctuating, so steps S33 to S35 are skipped to return to prevent erroneous error detection. Similarly, if it is determined in step S33 that P _MAX ≤ XP _MAX , it means that the maximum fuel pressure P _MAX is small enough so that it does not exceed the reference maximum value XP _MAX , and therefore a false error is detected. In order to prevent, skip steps S33 to S35 and return.

If it is determined in step S34 that P _MIN ≧ XP _MIN , the value of the fuel injection cylinder abnormality determination counter DCNT is decremented by one (step S36).
It is determined whether the abnormality determination counter DCNT has reached 0 (step S37). If it is determined that DCNT = 0, the error flag of the cylinder that is the target of fuel injection at this time is set to 1 (step S38).

Further, in step S37, the counter DCNT becomes 0.
If it is determined that the value has not reached, the process immediately returns and the steps of FIG. 7 are repeated. As a result, the error flag is set only when P _MIN ≧ XP _MIN is continuously determined by the reference count value XDCNT, and erroneous detection of abnormality is prevented.

For example, when an abnormality such as clogging or fuel leakage occurs in any of the injectors 5a to 5d, the fuel injection amount decreases in the case of clogging, and in the case of fuel leakage, the injector is opened. Since the relative fuel injection amount at the time becomes small, the fluctuation amount of the fuel pressure P, that is, the ripple becomes small. Therefore, in step S34 in FIG. 7, P _MIN ≧ XP _MIN
Abnormality is determined, and the reference count value XDC is further calculated for each fuel injection.
If the judgment is continuously made only NT times, the error flag becomes 1, and it is judged as abnormal in step S2 in FIG.

As described above, by determining the abnormality of the injectors 5a to 5d based on the magnitude of the ripple of the fuel pressure P, the failure can be detected regardless of the exhaust gas temperature, that is, the operating state, and the cylinder to which the failed injector belongs. Can be specified.

[0033]

As described above, according to the present invention, a plurality of cylinders for driving an internal combustion engine, an injector for injecting fuel into an intake passage for each cylinder, and a fuel transportation for supplying pressurized fuel to the injector. Means, fuel pressure detection means for detecting the pressure of fuel, fuel injection amount calculation means for calculating the fuel injection amount by the injector based on the operating state of the internal combustion engine, and based on the ripple value of the fuel pressure at the time of fuel injection A failure determination means for determining a failure of the injector is provided, and if the ripple value of the fuel pressure is smaller than the set value, it is determined that the injector of the cylinder to be detected has a failure.
Since failure detection is performed in all operating conditions regardless of exhaust gas temperature, a failure detection device for a fuel injection device that can detect failures regardless of operating conditions and that can identify the cylinder to which the injector belongs is obtained. It is effective.

Further, according to the present invention, the step of detecting the maximum value and the minimum value of the fuel pressure for each reference position corresponding to the predetermined crank angle of each cylinder, and the maximum value and the minimum value are set to the operating state of the internal combustion engine. A step of comparing with a corresponding reference maximum value and a reference minimum value respectively, and when the maximum value is less than the reference maximum value and the minimum value is less than the reference minimum value, the injector belonging to the cylinder for which the fuel pressure is detected is determined to be in failure. Including the step, if the ripple value is smaller than the set value, it is determined that the injector of the cylinder to be detected is in failure, so that failure detection is performed in all operating conditions regardless of the exhaust gas temperature. There is an effect that a failure detection method of a fuel injection device that can detect a failure independently and can specify a cylinder to which a failure injector belongs is obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a failure detection device for a fuel injection device according to the present invention.

FIG. 2 is a block diagram showing a configuration of an ECU in FIG.

FIG. 3 is a waveform diagram for explaining the operation of the apparatus of FIG.

FIG. 4 is a flowchart showing a main routine of the operation of the ECU in FIG.

5 is a flowchart showing an operation of updating the maximum value and the minimum value of the fuel pressure by the ECU in FIG.

FIG. 6 is a flowchart showing initialization and fuel injection operations by the ECU in FIG.

FIG. 7 is a flowchart showing an embodiment of a method for detecting a failure of a fuel injection device according to the present invention.

[Explanation of symbols]

1 Internal combustion engine 2a to 2d Intake passage 5a to 5d Injector 7 Fuel pump (fuel transportation means) 10 Pressure sensor (fuel pressure detection means) 20 ECU 30 Microcomputer B75 °, B5 ° Reference position F Fuel P Fuel pressure P _MAX maximum value P _MIN Minimum value S11 to S14 Steps to detect maximum value and minimum value S33, S34 Steps to compare maximum value and minimum value with reference maximum value and reference minimum value S38 Step to judge injector as failure

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[Procedure amendment]

[Submission date] June 22, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 2

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

However, if carbon or the like adheres to the nozzle portion of the injector to cause clogging or foreign matter enters the seal portion inside the injector to cause a fuel leak or the like, the injector, that is, the fuel injection device will malfunction, resulting in exhaust gas. Emissions in gas deteriorate and fuel efficiency also deteriorates. Therefore, there is a demand for a failure detection device for detecting a failure of a fuel injection device including an injector and warning the driver.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

Further, in the method of detecting a failure of a fuel injection device according to the present invention, a step of detecting the maximum value and the minimum value of the fuel pressure for each reference position corresponding to a predetermined crank angle of each cylinder, and the maximum value and the minimum value. The step of comparing the reference maximum value and the reference minimum value according to the operating state of the internal combustion engine, respectively, and when the maximum value is greater than the reference maximum value and the minimum value is greater than or equal to the reference minimum value, And determining that the injector to which it belongs is out of order.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

That is, it is judged whether or not the detected fuel pressure P is larger than the current maximum value P _MAX (step S11),
If P> P _MAX , the fuel pressure P is set to the maximum value P _MAX (step S12). If P ≦ P _MAX , it is determined whether or not the fuel pressure P is smaller than the present minimum value P _MIN (step S13), and if P <P _MIN , the fuel pressure P is set to the minimum value P _MIN . Yes (step S14). As a result, the maximum value P _MAX and the minimum value P _MIN are clipped in real time.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

[Correction content]

[0029] Further, P is _{if MIN} ≧ XP are determined to be _MIN, the value of the abnormality determination counter DCNT the fuel injection cylinder to decrement only one at step S34 (step S36),
It is determined whether the abnormality determination counter DCNT has reached 0 (step S37). If it is determined that DCNT = 0, the error flag of the cylinder that is the target of fuel injection at this time is set to 1 (step S38).

[Procedure Amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction content]

Further, according to the present invention, the step of detecting the maximum value and the minimum value of the fuel pressure for each reference position corresponding to the predetermined crank angle of each cylinder, and the maximum value and the minimum value are set to the operating state of the internal combustion engine. The step of comparing with the corresponding reference maximum value and reference minimum value respectively, and the maximum value is larger than the reference maximum value.
Ku and comprises minimum value and determining a failure of the injector belonging to the detection target cylinder fuel pressure when it is the reference minimum value or more, it is determined that the failure of the detection target cylinder injector when the ripple value is smaller than the set value By doing so, failure detection is performed in all operating conditions regardless of exhaust gas temperature, so failure detection can be performed regardless of operating status and failure detection of the fuel injection device that can identify the cylinder to which the injector belongs. There is an effect that the method can be obtained.

Claims (2)

[Claims] 1. A plurality of cylinders for driving an internal combustion engine, an injector for injecting fuel into an intake passage for each of the cylinders, a fuel transportation means for supplying pressurized fuel to the injector, and a pressure for the fuel. Fuel pressure detection means for detecting, fuel injection amount calculation means for calculating the fuel injection amount by the injector based on the operating state of the internal combustion engine, and failure of the injector based on a ripple value of the fuel pressure at the time of fuel injection A failure detection device for a fuel injection device, comprising: failure determination means for determining. 2. A step of detecting a maximum value and a minimum value of the fuel pressure for each reference position corresponding to a predetermined crank angle of each cylinder, and the maximum value and the minimum value being a reference maximum corresponding to an operating state of the internal combustion engine. A value and a reference minimum value respectively, and when the maximum value is equal to or less than the reference maximum value and the minimum value is equal to or less than the reference minimum value, the injector belonging to the fuel pressure detection target cylinder is determined to be defective. And a method of detecting a failure of a fuel injection device, the method including: