JP3258417B2 - Engine fuel pump failure detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel pump failure detecting device for an engine in which the discharge amount of a fuel pump is voltage-controlled to a required minimum according to the operating state of the engine.

[0002]

2. Description of the Related Art Heretofore, the discharge rate from a fuel pump disposed in a fuel tank has been substantially constant, and excess fuel has been returned to the fuel tank by a pressure regulator.
In this case, when the return amount from the pressure regulator increases, the fuel vapor also increases. The fuel vapor is once adsorbed by the canister and then supplied to the intake system of the engine. At that time, it had been released into the atmosphere, and there was a problem of air pollution.

In order to solve such a problem, conventionally, as disclosed in Japanese Patent Application Laid-Open No. 4-63962, for example, the discharge amount of a fuel pump is set to a required minimum according to the operating state of an engine. A fuel pump voltage control device for an internal combustion engine has been already invented in which voltage control is performed to eliminate air pollution due to purge discharge, improve durability of the fuel pump, and reduce battery power consumption.

However, this conventional apparatus has a problem that when an abnormality occurs in the combustion state of the engine, it cannot be reliably determined whether the engine control system is abnormal or the fuel pump has failed.

[0005]

According to the first aspect of the present invention, the voltage applied to the fuel pump is changed when the combustion state of the engine is abnormal, and based on the parameter measurement result corresponding to the change direction of the fuel discharge amount. An object of the present invention is to provide a fuel pump failure detection device for an engine that can reliably determine whether an abnormality has occurred in an engine control system or a failure in a fuel pump by performing failure detection of the fuel pump.

According to a second aspect of the present invention, in addition to the object of the first aspect, when the integrated value of the air-fuel ratio feedback correction amount is a lean signal, the discharge amount of the fuel pump is increased. When the integrated value of the air-fuel ratio feedback correction amount is a rich signal, the failure detection is performed without further deteriorating the combustion state of the engine by prohibiting the failure detection due to the decrease in the discharge amount of the fuel pump. It is an object of the present invention to provide an apparatus for detecting a failure of a fuel pump of an engine.

According to a third aspect of the present invention, in addition to the object of the first or second aspect of the present invention, a failure is detected by detecting a change in the angular velocity of a crankshaft by a crank angle sensor to detect a failure. It is an object of the present invention to provide an engine fuel pump failure detection device capable of performing failure detection by effectively utilizing an existing device without requiring a special device separately.

According to a fourth aspect of the present invention, in addition to the object of the first or second aspect of the present invention, clogging of an injector or the like is performed by detecting a return flow rate of fuel with a flow rate sensor to detect a failure. It is an object of the present invention to provide a fuel pump failure detection device for an engine which can accurately detect a failure of a fuel pump without being affected by the fuel pump.

[0009]

According to a first aspect of the present invention, there is provided an operating state detecting means for detecting an operating state of an engine, and a request for a discharge amount of a fuel pump based on an output of the operating state detecting means. An engine fuel pump failure detection device comprising: a voltage control unit that performs voltage control to a minimum; an abnormality detection unit that detects an abnormality in a combustion state of the engine; A discharge amount changing means for changing an applied voltage to the fuel pump to change a discharge amount of the fuel pump; and a failure detecting means for detecting a failure of the fuel pump based on a parameter measurement result corresponding to the change direction. It is a fuel pump failure detection device for an engine.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the feedback correction amount for making the air-fuel ratio the target air-fuel ratio based on the output of the air-fuel ratio sensor is integrated. Determining means for determining whether the value is a lean signal or a rich signal; and increasing the discharge amount of the fuel pump by the discharge amount changing means at the time of the lean signal determination by the determining means to detect a failure. A fuel pump failure detection device for an engine including a prohibition unit for prohibiting a failure detection due to a decrease in the discharge amount of the fuel pump at the time of signal determination.

According to a third aspect of the present invention, in addition to the configuration of the first or second aspect, the failure detecting means detects a change in the angular speed of the crankshaft with a crank angle sensor, and detects the change in the angular speed. When the value is within the specified value,
It is a fuel pump failure detection device for an engine that determines a failure of a fuel pump.

According to a fourth aspect of the present invention, in addition to the configuration of the first or second aspect of the invention, the failure detecting means is provided between the fuel pump discharge side and the fuel tank by a flow rate sensor. A fuel pump failure detection device for an engine that detects a change rate of a return flow rate from an installed pressure regulating valve and determines a failure of the fuel pump when the change rate of the return flow rate is within a predetermined value. .

[0013]

According to the first aspect of the present invention, as shown in the claim correspondence diagram of FIG. 7, the voltage control means P1 outputs the output of the operation state detection means P3 for detecting the operation state of the engine P2. , The discharge amount of the fuel pump P4 is controlled to the required minimum voltage. However, when the abnormality detection unit P5 detects an abnormality in the combustion state of the engine P2, the discharge amount changing unit P6 is controlled via the voltage control unit P1. Fuel pump P
By changing the applied voltage to the fuel pump P4
The amount of fuel discharged from the fuel cell.

Then, the failure detecting means P7 executes the above-described failure detection of the fuel pump P4 based on the parameter measurement result corresponding to the above-mentioned change direction. That is, when the combustion state of the engine becomes abnormal due to the engine control system or the fuel pump system, the variable of the fuel pump system is changed by the discharge amount changing means P6, and failure detection is executed based on the parameter measurement result in the change direction. Therefore, when the combustion state of the engine returns to normal due to the change in the above variables, it is a failure of the fuel pump system, and when the combustion state of the engine remains abnormal due to the change in the above variables, the engine control system Therefore, it is possible to reliably determine whether the engine control system is abnormal or the fuel pump system is abnormal.

According to the invention described in claim 2 of the present invention,
In addition to the effect of the first aspect of the present invention, when the integrated value of the feedback correction amount is a lean signal, the discharge amount changing means increases the discharge amount of the fuel pump, thereby eliminating one of the causes of the abnormality. In this state, the failure detection means performs the failure detection based on the parameter measurement result, so that the failure detection can be performed while satisfying the above-described request for increasing the fuel by the lean signal. Therefore, there is an effect that failure detection can be performed without further deteriorating the combustion state of the engine due to hesitation or misfire due to a lean air-fuel ratio.

In addition, when the integrated value of the feedback correction amount is a rich signal, the above-described prohibiting means prohibits the failure detection due to the decrease in the discharge amount of the fuel pump, so that the air-fuel ratio becomes over-lean due to the decrease in the discharge amount from the fuel pump. Can be prevented.

According to the third aspect of the present invention,
In addition to the effect of the first or second aspect of the present invention, the crank angle sensor is configured to detect a change in angular speed of the crankshaft to detect a failure, so that a special device for detecting a failure of the fuel pump is separately required. In addition, there is an effect that a failure can be detected by effectively using an existing device (crank angle sensor).

According to the invention described in claim 4 of the present invention,
In addition to the effects of the first and second aspects of the present invention, the fuel pump system is configured to detect the failure by detecting the return flow rate of the fuel by the flow rate sensor, so that the fuel pump system can be accurately controlled without being affected by clogging of the injector. There is an effect that a failure can be detected.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. The drawing shows an engine fuel pump failure detection measure. In FIG. 1, an air cleaner 1 for purifying intake air is shown.
An airflow sensor 3 is connected to the rear of the element 2 and the intake air amount Q is detected by the airflow sensor 3.

A throttle body 4 is connected to the rear of the above-mentioned airflow sensor 3, and a throttle valve 6 for controlling the amount of intake air is provided in a throttle chamber 5 in the throttle body 4. And this throttle valve 6
A surge tank 7 as an expansion chamber having a predetermined capacity is connected to the downstream intake passage, an intake manifold 9 communicating with an intake port 8 is connected downstream of the surge tank 7, and an injector 10 is connected to the intake manifold 9. Is arranged.

On the other hand, the above-mentioned intake port 8 and exhaust port 13 which are appropriately communicated with the combustion chamber 12 of the engine 11 have:
Intake valve 14 that is opened and closed by a valve operating mechanism (not shown)
And an exhaust valve 15 respectively, and a spark plug (not shown) having a spark gap facing the combustion chamber 12 is mounted on the cylinder head.

An O ₂ sensor 17 as an air-fuel ratio sensor is provided in an exhaust passage 16 communicating with the above-described exhaust port 13, and a catalytic converter 18 for rendering harmful gas harmless behind the exhaust passage 16 is a so-called catalyst. A wrist is connected, and an O ₂ sensor 20 as an air-fuel ratio sensor is also attached to the exhaust passage 19 downstream of the catalytic converter 18.

A bypass passage 21 for bypassing the throttle valve 6 is provided. An ISC valve 22 as an ISC (idle speed control) mechanism is interposed in the bypass passage 21, while a downstream side of the element 2 of the air cleaner 1 is provided. , An intake air temperature sensor 23, a throttle sensor 24 on the throttle body 4, and a water temperature sensor 25 on the water jacket.

On the other hand, the evaporative fuel supply device 26 is configured as follows. That is, the fuel tank 27 and the inlet side of the canister 28 are connected by a first purge line 29, and a solenoid valve 30 that is opened only when the engine is running is interposed in the first purge line 29, and the outlet of the canister 28 is connected. The inlet side of the purge valve 31 is connected to the inlet side of the purge valve 31 by a second purge line 32, and the outlet side of the purge valve 31 is connected to the surge tank 7 of the intake system by a third purge line 33. The fuel is adsorbed by the canister 28 and the evaporated fuel is introduced into the intake system via the purge valve 31.

The fuel supply system 34 for supplying the fuel in the fuel tank 27 to the injector 10 is constructed as shown in FIG. That is, suction line 3
5 is immersed in the above-described fuel tank 27 and provided with a variable discharge fuel pump 36.
The filter 38 is connected to the discharge line 37 of No. 6 and the downstream line 39 of the filter 38 is connected to the above-described injector 10, while the return line 40 from the injector 10 is provided with a pressure regulator 41 and a flow sensor 42. I have.

The fuel pump 36 is driven by a motor 43, and the motor 43 is connected to a battery 44 with a variable resistor 45 so as to obtain a rotation speed corresponding to the applied voltage.
Connected through.

FIG. 3 shows a control circuit of the engine fuel pump failure detecting device. The CPU 50 controls the engine speed Ne from the distributor 46, the intake air amount Q from the air flow sensor 3, and the engine water temperature t from the water temperature sensor 25.
ROM 51 based on various necessary signal inputs such as w, angular velocity ω and angular velocity change Δω from crank angle sensor 47, air-fuel ratio A / F from O ₂ sensor 17 and change rate L of return flow rate from flow rate sensor 42. The voltage control circuit 48, the injector 10,
The drive of the failure determination lamp 52 and the misfire determination lamp 53 is controlled, and the RAM 54 stores data, maps, and the like corresponding to the acceleration hesitation threshold α and the misfire determination threshold β shown in FIG.

Here, the above-described crank angle sensor 47 detects the angular velocity ω and the angular velocity change Δω of the crankshaft. The above-described voltage control circuit 48 is connected to the variable resistor 4 shown in FIG.
5 corresponding to the operating state of the engine 11
3 by controlling the applied voltage to the motor 43
Of the fuel pump 3
The voltage of the ejection amount of No. 6 is controlled to the required minimum.

Further, the CPU 50 is provided with the engine 11
Operating state detecting means (refer to the first and second steps 61 and 62 in the flow chart shown in FIG. 4) for detecting the operating state of the engine and the required discharge amount of the fuel pump 36 based on the output of the operating state detecting means. Voltage control means (refer to the third step 63 in the flowchart shown in FIG. 4) and abnormality detection means for detecting the presence or absence of an abnormality in the combustion state of the engine 11 (see the fifth step 65 in the flowchart shown in FIG. 4). ) And the air-fuel ratio based on the output of the O ₂ sensor 17 is set to a target air-fuel ratio, for example, the stoichiometric air-fuel ratio A / F =
Determining means for determining whether the integrated value CFBZ of the feedback correction amount CFB for achieving 14.7 is a lean signal requiring a fuel increase or a rich signal requiring a fuel decrease (see the seventh step 67 in the flowchart shown in FIG. 4); When the abnormality is detected by the abnormality detecting means, the fuel pump 36
By changing the applied voltage to the fuel pump 36
A discharge amount changing means (see the ninth step 69 in the flow chart shown in FIG. 4) for changing the discharge amount of the ink jet head and a parameter corresponding to the above-mentioned change direction (in this embodiment, the angular velocity change Δ
ω), the failure detection means for performing failure detection of the fuel pump 36 based on the measurement result (see the twelfth step 72 in the flowchart shown in FIG. 4), and the discharge of the fuel pump 36 when the rich signal is determined by the above-described determination means. The prohibition means for prohibiting the failure detection due to the decrease in the amount (refer to the fourteenth step 74 in the flowchart shown in FIG. 4) and also the discharge amount changing means described above (refer to the ninth step 69).
Is configured to apply a maximum voltage to the fuel pump 36 at the time of the lean signal determination by the above-described determination means, increase the discharge amount to the fuel pump 36, and perform failure detection.

Further, in this embodiment, the above-described failure detecting means (see the twelfth step 72) includes the crank angle sensor 47.
The change in the angular velocity of the crankshaft Δω is detected, and when the change in the angular velocity is within a predetermined value, for example, the acceleration hesitation threshold α, the failure of the fuel pump 36 is determined.

The operation of the fuel pump detecting device for an engine constructed as described above will be described below in detail with reference to the flowchart of FIG. In a first step 61, the CPU 50 reads various signals necessary for determining the operating state of the engine 11, such as the engine speed Ne from the distributor 46, the intake air amount Q from the air flow sensor 3, and the engine water temperature tw from the water temperature sensor 25. Execute

In the second step 62, the CPU 50 calculates the load CE based on the equation CE = Q / Ne. Next, in a third step 63, the CPU 50 reads applied voltage data corresponding to the current engine operating state from a map (not shown) in the RAM 54 corresponding to the load CE and the engine speed Ne, and then reads the voltage. The voltage applied to the motor 43 is determined via the control circuit 48, and the fuel pump 36 is driven via the motor 43 to control the discharge amount of the fuel pump 36 to a required minimum corresponding to the current engine operating state. I do.

Next, in a fourth step 64, the CPU 50 reads the angular velocity change Δω from the crank angle sensor 47. Next, in a fifth step 65, the CPU 50 determines the current angular velocity change Δω.
And acceleration hesitation threshold α, and Δω <α
Is normal, the process returns to the first step 61, while Δ
When ω> α, the process proceeds to the next sixth step 66.

In the sixth step 66, the CPU 50 reads the integrated value CFBZ of the feedback correction amount. Next, in a seventh step 67, the CPU 50 determines that the integrated value CFBZ of the feedback correction amount and the air-fuel ratio are equal to the stoichiometric air-fuel ratio A.
/F=14.7 (λ = 1) and 0% which does not require correction, and determines whether the integrated value CFBZ is a lean signal or a rich signal. )
On the other hand, the process proceeds to the next eighth step 68, while the process proceeds to another thirteenth step 73 when the rich signal is determined (when the determination is NO).

In the above-described eighth step 68, the CPU 50 executes fuel increase correction in response to the lean signal. This fuel increase is a correction based on the final injection pulse width for the injector 10.

Next, in a ninth step 69, the CPU 50 prohibits the voltage control of the fuel pump 36 corresponding to the engine operating state, applies the maximum voltage to the motor 43,
The discharge amount of the fuel pump 36 is increased. That is,
At this point, it is unclear whether the abnormality of the engine 11 is caused by a failure of the fuel pump system or an abnormality of the engine control system, so that one factor of the occurrence of the abnormality is eliminated.

Next, at a tenth step 70, the CPU 50 reads the angular velocity change Δω from the crank angle sensor 47 again. Next, in an eleventh step 71, the CPU 50 compares the current angular velocity change Δω with the acceleration hesitation threshold α, and proceeds to the fifteenth step 75 when Δω> α continues to be abnormal, while proceeds to the fifteenth step 75 when Δω <α is normal. The process proceeds to the twelfth step 72.

In the twelfth step 72, the CPU 50 determines that the fuel pump system has a failure, and turns on the failure determination lamp 52. That is, when an abnormality occurs in the engine 11 and it is not clear whether the abnormality is due to a failure in the fuel pump system or an abnormality in the engine control system, the control of the fuel pump system is first prohibited, and
After removing one of the factors, the engine 11 has returned to normal, so it is determined that the fuel pump system has failed.

On the other hand, in the above-mentioned thirteenth step 73, the CP
U50 executes fuel reduction correction in response to the rich signal. Note that this fuel reduction is a correction based on the final injection pulse width for the injector 10, and is not a reduction in the discharge amount on the fuel pump 36 side.

Next, in a fourteenth step 74, the CPU 50 inhibits failure detection due to a decrease in the discharge amount of the fuel pump 36. Therefore, the fuel pump 36 is under voltage control via the motor 43.

Next, in a fifteenth step 75, the CPU 50 reads the angular velocity change Δω from the crank angle sensor 47 again. Next, in a sixteenth step 76, the CPU 50 compares the current angular velocity change Δω with the misfire determination threshold β, and determines that Δω>
When the determination of β is YES, the process proceeds to the next seventeenth step 77, while when the determination of Δω <β is NO, the process proceeds to another eighteenth step 78.

In the above-described seventeenth step 77, the CPU 50
Determines that the engine control system is misfired, and turns on the misfire determination lamp 53.
The CPU 50 determines that the operation is normal.

In short, when the abnormality detecting means (see the fifth step 65) detects an abnormality in the combustion state of the engine 11, the above-mentioned discharge amount changing means (see the ninth step 69) changes the voltage applied to the fuel pump 36. (In this embodiment, the fuel discharge amount from the fuel pump 36 is changed).

Then, the failure detecting means (the twelfth step 7)
2) executes the above-described failure detection of the fuel pump 36 based on the measurement result of the parameter (angular velocity change Δω in this embodiment) corresponding to the above-mentioned change direction.

That is, when the combustion state of the engine 11 becomes abnormal due to the engine control system or the fuel pump system, the variable of the fuel pump system, that is, the fuel discharge amount is changed by the discharge amount changing means (refer to ninth step 69). Since the failure detection is performed based on the measurement result of the parameter (angular velocity change) with respect to the change direction, if the combustion state of the engine returns to normal due to the change of the above-described variable (fuel discharge amount), the failure of the fuel pump system If the combustion state of the engine remains abnormal due to the change of the above-mentioned variable (fuel discharge amount), it is an abnormality of the engine control system. Thus, there is an effect that it is possible to reliably determine whether or not a failure has occurred.

In addition, when the determining means (see the seventh step 67) determines that the integrated value CFBZ of the feedback correction amount is a lean signal, the above-mentioned discharge amount changing means (see the ninth step 69) operates the fuel pump. By increasing the discharge amount of 36, one of the causes of the abnormality is removed,
In this state, the above-described failure detecting means (the twelfth step 7
2) performs the failure detection based on the measurement result of the parameter (angular velocity change Δω), so that the failure detection can be performed while satisfying the above-described request for the fuel increase by the lean signal. Therefore, there is an effect that failure detection can be performed without further deteriorating the combustion state of the engine 11 due to hesitation or misfire due to lean air-fuel ratio.

The above-described determination means (seventh step 67)
When the integrated value CFBZ of the feedback correction amount is determined to be a rich signal, the prohibiting means (see the fourteenth step 74) prohibits the failure detection due to the decrease in the discharge amount of the fuel pump 36. There is an effect that it is possible to prevent the air-fuel ratio from becoming overlean by reducing the discharge amount from the air-fuel ratio.

Further, when the failure is detected by detecting the angular velocity change Δω of the crankshaft by the crank angle sensor 47 as in the above-described embodiment, a special device for detecting the failure of the fuel pump 36 is not required. There is an effect that the failure detection can be performed by effectively using the existing device (crank angle sensor 47).

FIG. 6 is a flowchart showing another embodiment of the apparatus for detecting a failure of the fuel pump of an engine. In this embodiment, the circuit devices shown in FIGS. 1, 2 and 3 are used. In the case of this embodiment, the above-described CPU 50 is the engine 1
1 and a request for the discharge amount of the fuel pump 36 based on the output of the operating state detecting means (see first and second steps 81 and 82 in the flowchart shown in FIG. 6). Voltage control means for controlling the voltage to a minimum (see the third step 83 in the flowchart shown in FIG. 6) and abnormality detection means for detecting the presence or absence of an abnormality in the combustion state of the engine 11 (the fifth step 85 in the flowchart shown in FIG. 6) ) And an air-fuel ratio based on the output of the O ₂ sensor 17 is set to a target air-fuel ratio, for example, a stoichiometric air-fuel ratio A / F =
Determining means for determining whether the integrated value CFBZ of the feedback correction amount CFB for achieving 14.7 is a lean signal requiring a fuel increase or a rich signal requiring a fuel decrease (see a seventh step 87 in the flowchart shown in FIG. 6); When the abnormality is detected by the abnormality detecting means, the fuel pump 36
By changing the applied voltage to the fuel pump 36
The discharge amount changing means for changing the discharge amount (see the ninth step 89 in the flowchart shown in FIG. 6) and the fuel based on the measurement result of the parameter (the return flow rate change rate L in this embodiment) corresponding to the above change direction. Failure detection means for performing failure detection of the pump 36 (see the twelfth step 92 in the flowchart shown in FIG. 6), and prohibition of failure detection due to a decrease in the discharge amount of the fuel pump 36 when a rich signal is determined by the determination means described above. The above-mentioned discharge amount changing means (see ninth step 89) also serves as the means (see the fourteenth step 94 in the flowchart shown in FIG. 6). A minimum voltage is applied to the fuel pump 36 to increase the discharge rate to detect a failure. There.

In this embodiment, the above-described failure detecting means (see the twelfth step 92) is interposed between the discharge side of the fuel pump 36 and the fuel tank 27 by the flow rate sensor 42 (see FIGS. 2 and 3). The change rate L of the return flow rate from the pressure regulator 41 is detected, and when the change rate L of the return flow rate is within a predetermined value L0, the failure of the fuel pump 36 is determined.

The operation of the fuel pump detecting device for an engine constructed as described above will be described in detail below with reference to the flowchart of FIG. In a first step 81, the CPU 50 reads various signals necessary for determining the operating state of the engine 11, such as the engine speed Ne from the distributor 46, the intake air amount Q from the airflow sensor 3, and the engine water temperature tw from the water temperature sensor 25. Execute

In the second step 82, the CPU 50 calculates the load CE based on the equation CE = Q / Ne. Next, in a third step 83, the CPU 50 reads applied voltage data corresponding to the current engine operating state from a map (not shown) in the RAM 54 corresponding to the load CE and the engine speed Ne, and then reads the voltage. The voltage applied to the motor 43 is determined via the control circuit 48, and the fuel pump 36 is driven via the motor 43 to control the discharge amount of the fuel pump 36 to a required minimum corresponding to the current engine operating state. I do.

Next, in a fourth step 84, the CPU 50 reads the angular velocity change Δω from the crank angle sensor 47. Next, in a fifth step 85, the CPU 50 determines the current angular velocity change Δω.
Is compared with the acceleration hesitation threshold α (see FIG. 5). When Δω <α is normal, the process returns to the first step 81. On the other hand, when Δω> α is abnormal, the next sixth step 86 is performed.
Move to

In the sixth step 86, the CPU 50 reads the integrated value CFBZ of the feedback correction amount. Next, in a seventh step 87, the CPU 50 determines whether the integrated value CFBZ of the feedback correction amount and the air-fuel ratio are equal to the stoichiometric air-fuel ratio A.
/F=14.7 (λ = 1) and 0% which does not require correction, and determines whether the integrated value CFBZ is a lean signal or a rich signal. )
On the other hand, the process proceeds to the next eighth step 88, while the process proceeds to another thirteenth step 93 when the rich signal is determined (when the determination is NO).

In the above-described eighth step 88, the CPU 50 executes the fuel increase correction in response to the lean signal. This fuel increase is a correction based on the final injection pulse width for the injector 10.

Next, at a ninth step 89, the CPU 50 inhibits the voltage control of the fuel pump 36 corresponding to the engine operating state, and applies the maximum voltage to the motor 43,
The discharge amount of the fuel pump 36 is increased. That is,
At this point, it is unclear whether the abnormality of the engine 11 is caused by a failure of the fuel pump system or an abnormality of the engine control system, so that one factor of the occurrence of the abnormality is eliminated.

Next, in a tenth step 90, the CPU 50 reads the return flow rate change rate L from the flow rate sensor 42.
Next, at an eleventh step 91, the CPU 50 compares the return flow rate change rate L with a predetermined value L0, and when the return flow rate change rate normally increases in response to the fuel pump discharge amount increase control where L> L0, the fifteenth step. On the other hand, if the return flow rate change rate does not increase contrary to the fuel pump discharge rate increase control in which L <L0, the process proceeds to step 95.
Move to two steps 72. This twelfth step 92
Then, the CPU 50 determines that the fuel pump system has a failure, and turns on the failure determination lamp 52.

On the other hand, in the above thirteenth step 93, the CP
U50 executes fuel reduction correction in response to the rich signal. Note that this fuel reduction is a correction based on the final injection pulse width for the injector 10, and is not a reduction in the discharge amount on the fuel pump 36 side.

Next, in a fourteenth step 94, the CPU 50 inhibits failure detection due to a decrease in the discharge amount of the fuel pump 36. Therefore, the fuel pump 36 is under voltage control via the motor 43.

Next, at a fifteenth step 95, the CPU 50 reads the angular velocity change Δω from the crank angle sensor 47 again. Next, in a sixteenth step 96, the CPU 50 compares the current angular velocity change Δω with the misfire determination threshold β, and determines that Δω>
When the determination of β is YES, the process proceeds to the next seventeenth step 97, while when the determination of Δω <β is NO, the process proceeds to another eighteenth step 98.

At the above-described seventeenth step 97, the CPU 50
Determines that the engine control system is misfired, and turns on the misfire determination lamp 53.
Then, the CPU 50 determines that the operation is normal.

As described above, since the failure is detected by detecting the return flow rate of the fuel by the flow rate sensor 42, the failure of the fuel pump system is accurately detected without being affected by the clogging of the injector 10. There is an effect that can be. The other effects are almost the same as in the previous embodiment.

In the correspondence between the configuration of the present invention and the above-described embodiment, the operating state detecting means of the present invention is the first embodiment of the present invention.
And the second steps 61, 62, 81, and 82. Similarly, the voltage control means performs the third step 63,
83, the abnormality detecting means performs fifth steps 65, 8
5, the determination means corresponds to the seventh steps 67 and 87, the discharge amount changing means corresponds to the ninth steps 69 and 89, the failure detection means corresponds to the twelfth steps 72 and 92, The prohibiting means corresponds to the fourteenth steps 74 and 94, the pressure regulating valve corresponds to the pressure regulator 41, the fuel pump corresponds to the fuel pump 36, and the air-fuel ratio sensor corresponds to the O ₂ sensor 17. However, the present invention is not limited to only the configuration of the above-described embodiment.

[Brief description of the drawings]

FIG. 1 is a system diagram of an engine including a fuel pump failure detection device according to the present invention.

FIG. 2 is a system diagram showing a fuel pump system.

FIG. 3 is a control circuit block diagram of the fuel pump failure detection device.

FIG. 4 is a flowchart illustrating a failure detection process.

FIG. 5 is an explanatory diagram of an acceleration hesitation threshold value and a misfire determination threshold value.

FIG. 6 is a flowchart showing another embodiment of the failure detection processing.

FIG. 7 is a diagram corresponding to claims.

[Explanation of symbols]

Reference Signs List 17 O ₂ sensor 27 Fuel tank 36 Fuel pump 41 Pressure regulator 42 Flow rate sensor 47 Crank angle sensor 61, 62, 81, 82 Operating state detecting means 63, 83 Voltage control means 65, 85 Abnormality Detecting means 67, 87 determining means 69, 89 discharge amount changing means 72, 92 fault detecting means 74, 94 prohibiting means

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-305349 (JP, A) JP-A-3-260365 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02M 37/08 F02D 41/14 310 F02D 41/22 330 F02D 45/00 362

Claims (4)

(57) [Claims] 1. An engine comprising: an operating state detecting means for detecting an operating state of an engine; and a voltage controlling means for controlling a discharge amount of a fuel pump to a required minimum voltage based on an output of the operating state detecting means. A fuel pump failure detection device, comprising: abnormality detection means for detecting an abnormality in the combustion state of an engine; and, when an abnormality is detected by the abnormality detection means, changing a voltage applied to the fuel pump to change a discharge amount of the fuel pump. A fuel pump failure detection device for an engine, comprising: a discharge amount changing means for causing the fuel pump to detect a failure of the fuel pump based on a parameter measurement result corresponding to the change direction. A determining means for determining whether an integrated value of a feedback correction amount for setting an air-fuel ratio to a target air-fuel ratio is a lean signal or a rich signal based on an output of the air-fuel ratio sensor; At the same time, the discharge amount changing means increases the discharge amount of the fuel pump to detect a failure, and at the time of rich signal determination by the determination means, includes a prohibition means for inhibiting failure detection due to a decrease in the discharge amount of the fuel pump at the time of rich signal determination. The fuel pump failure detection device for an engine according to claim 1. 3. The engine according to claim 1, wherein said failure detecting means detects a change in the angular speed of the crankshaft by a crank angle sensor, and determines a failure in the fuel pump when the change in the angular speed is within a predetermined value. Fuel pump failure detection device. 4. The failure detecting means detects a rate of change of a return flow rate from a pressure regulating valve interposed between a fuel pump discharge side and a fuel tank by a flow rate sensor, and determines a rate of change of the return flow rate to a predetermined value. The engine fuel pump failure detecting device according to claim 1 or 2, wherein the failure of the fuel pump is determined when the value is within the value.