JPH08312437A - Fuel injection control system abnormality diagnosis device of diesel engine - Google Patents

Abstract

PURPOSE: To detect not only the abnormal condition of a fuel injection control system, but also the abnormal condition of the switching means of a relay for fail safe and the like. CONSTITUTION: To a solenoid spill valve (SPV) 30 to regulate the fuel injection amount, a power source is fed through an SPV relay 86 of a constant closing type. The collector (output terminal) of the output transistor 87 of a driving circuit 84 to drive the SPV 30 is connected also to the input terminal of an abnormality detecting circuit 85. By connecting a pulldown resistance 95 between the input terminal of the abnormality detecting circuit 85 and a gland terminal, the output of the abnormality detecting circuit 85 is converted to the high level/ the low level according to the ON/OFF of the SPV relay 86, when the output transistor 87 is in the OFF condition. By deciding the output of the abnormality detecting circuit 85 by turning OFF the SPV relay 86 temporarily, in the engine stopping condition or in the OFF time of the output transistor 87, the OFF operation of the SPV relay 86 is checked beforehand.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a fail-safe function for determining whether or not there is an abnormality in a fuel injection control system of a diesel engine and interrupting the power supply to the fuel injection device by an opening / closing means such as a relay when there is an abnormality. The present invention relates to a fuel injection control system abnormality diagnosis device for a diesel engine.

[0002]

2. Description of the Related Art Generally, a fuel injection control system for a diesel engine drives an injection pump by the power of the engine and controls the fuel injection amount of the injection pump by an actuator such as an electromagnetic spill valve. In this system, if the actuator is constantly energized due to a failure of the actuator drive circuit, a short circuit of the harness, etc., the fuel injection amount increases and the rotation of the engine abnormally increases. For this reason, self-diagnosis is performed for the presence or absence of an abnormality in the fuel injection control system, and in the event of an abnormality, the fail-safe relay provided between the actuator and the power supply is turned off to shut off the power supply to the actuator. There is.

[0003]

However, in the above-mentioned conventional structure, when the fail-safe relay becomes uncontrollable due to contact fusion, short-circuit of the signal line or the like, even if an abnormality of the fuel injection control system is detected. , The fail-safe relay cannot be turned off, and the actuator continues to be energized.

The present invention has been made in view of the above circumstances, and therefore an object thereof is to detect not only the abnormality of the fuel injection control system but also the abnormality of the opening / closing means such as a fail-safe relay. An object of the present invention is to provide a fuel injection control system abnormality diagnosis device for a diesel engine.

[0005]

In order to achieve the above object, a fuel injection control system abnormality diagnostic device for a diesel engine according to claim 1 of the present invention is directed to a fuel injection device when the fuel injection control system for a diesel engine is abnormal. An opening / closing means for cutting off the power supply of the device, a drive circuit for driving the fuel injection device, a control means for controlling the opening / closing means and the drive circuit, and an output of the drive circuit connected to an output terminal of the drive circuit. An abnormality detection circuit that outputs a signal of a voltage level according to ON / OFF of the opening / closing means when the transistor is in an OFF state, and an output from the control means to the opening / closing means and the drive circuit and the abnormality detection circuit. The presence / absence of abnormality of the opening / closing means and the presence / absence of abnormality of the fuel injection control system are determined based on the output of

In this case, a pull-down resistor is connected between the input terminal of the abnormality detection circuit and the ground terminal, the output transistor of the drive circuit is in the OFF state, and the opening / closing means is in the OFF state. In this case, the input potential of the abnormality detection circuit may be reduced by the pull-down resistor.

Further, when the output transistor of the drive circuit is in an off state, an off signal is output from the control means to the opening / closing means to determine whether the opening / closing means is abnormal. It is preferable to activate the warning means in the event of an abnormality.

[0008]

The potential of the output terminal of the drive circuit for driving the fuel injection device changes according to the on / off state of the output transistor of the drive circuit and the on / off state of the opening / closing means. A change in the potential of the output terminal of the drive circuit is detected by the abnormality detection circuit, and when the output transistor of the drive circuit is in the OFF state (fuel injection stopped state), a signal of a voltage level according to ON / OFF of the opening / closing means is output. Output from the abnormality detection circuit. Further, in claim 1, by comprehensively judging the output from the control means to the opening / closing means and the drive circuit and the output of the above-mentioned abnormality detection circuit, the presence / absence of abnormality of the opening / closing means and the abnormality of the fuel injection control system are detected. Determine presence / absence.

Further, according to a second aspect of the present invention, when the opening / closing means is switched to the off state when the output transistor of the drive circuit is in the off state (fuel injection stopped state), the connection is made between the input terminal of the abnormality detection circuit and the ground terminal. The input pull-down resistor lowers the input potential of the abnormality detection circuit. With this, by switching the opening / closing means from ON → OFF → ON while the fuel injection is stopped, the input potential / output potential of the abnormality detection circuit is switched. It is possible to check on / off.

On the other hand, in the configuration in which the pull-down resistor is omitted (conventional configuration), even if the switching means is turned on / off when the output transistor of the drive circuit is in the off state, the input potential / output potential of the abnormality detection circuit Does not change and the on / off state of the opening / closing means cannot be confirmed.

According to another aspect of the present invention, when the output transistor of the drive circuit is in the off state, the control means outputs an off signal to the opening / closing means to temporarily turn off the opening / closing means. The off operation of the opening / closing means is confirmed by looking at the output, and if the opening / closing means does not operate normally, the warning means is activated to warn the driver.

[0012]

An embodiment of the present invention will be described below with reference to the drawings. First, the schematic configuration of the entire system will be described with reference to FIG. The injection pump 11 is a time-controlled electronically controlled distribution type injection pump, and the output of the diesel engine 12 is transmitted to the drive pulley 13 as a driving force of the injection pump 11 via a belt (not shown) or the like. At the center of the drive pulley 13, the drive shaft 1
4 is fixed, and in the middle of this drive shaft 14,
A vane-type fuel feed pump 16 (shown in a 90 ° expanded state in FIG. 6) for pressure-feeding fuel supplied from a fuel tank (not shown) to the pump chamber 15 is provided,
The fuel feed pump 16 is rotationally driven by the drive shaft 14. Further, a disk-shaped pulsar 17 is fixed to the base end side of the drive shaft 14, and the rotation of the pulsar 17 is detected by a rotation speed sensor 18.
The base end portion of the drive shaft 14 is connected to the cam disk 19 via a coupling (not shown).

A roller ring 20 is provided between the cam disk 19 and the pulsar 17, and the roller ring 2 is provided.
A plurality of cam rollers 21 facing the cam face of the cam disk 19 are provided along the circumference of 0. The cam faces of the cam disc 19 are formed by the same number as the number of cylinders of the diesel engine 12, and the cam disc 19 is urged by the pulling 22 to bring the cam face into contact with the cam roller 21. A plunger 23 for fuel pressurization is fixed to the center of the cam disk 19. The cam disk 19 and the plunger 23 rotate in association with the rotation of the drive shaft 14, and the cam face of the cam disk 19 contacts the cam roller 21. By rotating while rotating, the plunger 23 is given two movements of rotation and reciprocation.

The plunger 23 is slidably fitted in a cylinder 25 provided in the pump housing 24, and the reciprocating motion of the plunger 23 causes the fuel in the pump chamber 15 to be sucked into the cylinder 25 from the suction port 26. The stroke and the compression stroke in which the fuel sucked into the cylinder 25 is pressure-fed to the fuel injection nozzle 28 of each cylinder of the diesel engine 12 through the fuel distribution passage 27 and injected into each cylinder are alternately repeated.

A spill passage 29 for fuel overflow is formed in the pump housing 24 so that the inside of the cylinder 25 communicates with the pump chamber 15. The spill passage 29 has a spill passage 29 in the middle thereof for adjusting the fuel injection amount. An electromagnetic spill valve 30 is provided. The electromagnetic spill valve 30 is a normally open type valve, and when the solenoid coil 31 is de-energized, the valve element 32 is opened and the fuel in the cylinder 25 passes through the spill passage 29 into the pump chamber 15. Spilled into
When the solenoid coil 31 is energized, the valve body 32 is closed and the outflow of fuel from the cylinder 25 to the pump chamber 15 is blocked. With this configuration, when the electromagnetic spill valve 30 is fully opened (energization of the solenoid coil 31 is turned off) during the compression stroke of the plunger 23, the cylinder 2
The fuel in 5 is depressurized and the fuel injection from the fuel injection nozzle 28 is stopped. The control of the fuel injection amount injected from the fuel injection nozzle 28 is performed by controlling the opening of the electromagnetic spill valve 30 by controlling the power supply to the solenoid coil 31 at a timely cutoff.

On the other hand, below the pump housing 24,
A timer device 33 (90 ° in FIG. 6 for controlling fuel injection timing)
(Shown in the unfolded state). The timer device 33 controls the position of the roller ring 20 with respect to the rotation direction of the drive shaft 14 to control the timing at which the cam face of the cam disc 19 crosses over the cam roller 21 to reciprocate the cam disc 19 and the plunger 23. It controls the timing. The timer device 33 is operated by hydraulic pressure, and includes a timer housing 34 and a timer piston 3 slidably housed in the timer housing 34.
5 and a spring 3 for urging the timer piston 35
The timer piston 35 is connected to the roller ring 20 via the slide pin 37.

The fuel pressurized by the fuel feed pump 16 is introduced into the timer housing 34, and the position of the timer piston 35 is determined by the balance between the fuel pressure and the elastic force of the spring 36. This allows
The position of the roller ring 20 is determined, and the cam disc 19
The reciprocating timing of the plunger 23 is determined via the. Then, by adjusting the fuel pressure in the timer housing 34 with the timing control valve 38, the reciprocating timing of the plunger 23 is adjusted and the fuel injection timing is adjusted.

On the other hand, in the diesel engine 12, a sub combustion chamber 40 is formed above the main combustion chamber 39 of each cylinder, and in this sub combustion chamber 40, a glow plug 41 for assisting the starting is provided.
Is attached. The intake pipe 42 of the diesel engine 12 includes a compressor 44 of a turbocharger 43.
The exhaust pipe 45 is provided with a turbine 46 of the turbocharger 43 and a wastegate valve 47 for adjusting the boost pressure. A part of the exhaust gas flowing through the exhaust pipe 45 passes through the exhaust gas recirculation passage 48 and the intake pipe 42.
The exhaust gas recirculation amount is adjusted by controlling the opening degree of an exhaust gas recirculation control valve (EGR valve) 49 that is returned to the inside of the exhaust gas recirculation passage 48 by a vacuum switching valve (VSV) 50. To be done.

A throttle valve 57 which is opened / closed in association with the depression amount of the accelerator pedal 51 is provided in the middle of the above-mentioned intake pipe 42, and a bypass passage 52 is provided in parallel with the throttle valve 57. A bypass throttle valve 53 is provided at 52. The intake throttle mechanism 58 that controls the opening and closing of the bypass throttle valve 53 has two VSs.
It is composed of V54 and V55 and an actuator 56 having a two-stage diaphragm chamber driven by these. The bypass throttle valve 53 is controlled to a half open state in order to reduce vibration and noise during idle operation, is controlled to a fully open state during a normal operation, and is kept fully closed during an operation stop.

On the other hand, an electronic control unit (hereinafter referred to as "ECU") 61 for controlling the operation of the diesel engine 12 is
An intake air temperature sensor 62 for detecting the intake air temperature, a throttle opening sensor 63 for detecting the opening of the throttle valve 57, an intake pressure sensor 64 for detecting the intake pressure, a water temperature sensor 65 for detecting the engine cooling water temperature, a crank of the diesel engine 12 Based on various signals output from the crank angle sensor 66, the rotation speed sensor 18 that detects the rotation speed of the injection pump 11, and the like, a pulse signal corresponding to the rotation speed of a shaft (not shown), the electromagnetic spill valve 30, timing The control valve 38, the glow plug 41, the VSVs 50, 54, 55, etc. are controlled according to the operating state.

As shown in FIG. 5, the ECU 61 is mainly composed of a microcomputer 75, and the microcomputer 75 includes a CPU 67, a ROM 68 and a RAM 6.
9. Backup R backed up by battery 70
It is composed of an AM 71, an input port 72, an output port 73, a bus 74 connecting these parts, and the like. ECU
Reference numeral 61 includes a power supply circuit 76 fed from the battery 70 through the main relay 60 (see FIG. 4), an A / D converter 77 for A / D converting the various sensor signals described above, an ignition switch 78, and an idle switch 79. Also, an input buffer 81 for receiving the switch input from the starter switch 80, a waveform shaping circuit 82 for shaping the pulse signal output from the rotation speed sensor 18, etc., a glow plug 41.
Output circuit 83 for outputting a drive signal to an electromagnetic spill valve 3
A drive circuit 84 for driving 0 and an abnormality detection circuit 85 for detecting an abnormality described later are provided.

The microcomputer 75 controls ON / OFF of the main relay 60 (see FIG. 4) provided in the energizing path connecting the battery 70 and the power supply circuit 76, and when the ignition switch 78 is turned on, the main relay is immediately turned on / off. 60 is turned on and the ignition switch 7
Even after turning off 8, the main relay 60 is kept on for a predetermined time (for example, 2 seconds).

Next, a circuit configuration relating to abnormality diagnosis / fail safe of the fuel injection control system will be described with reference to FIG.
Power is supplied to the solenoid coil 31 of the electromagnetic spill valve 30 from a battery terminal (+ B) through a contact 86a of a normally-open SPV relay 86 (opening / closing means). Output transistor 8 of drive circuit 84 for driving electromagnetic spill valve 30
7, the emitter is grounded and the collector is the drive circuit 84.
Connected to the output terminal of the electromagnetic spill valve 3
Zero solenoid coil 31 is connected. The drive coil 86b of the SPV relay 86 has a battery terminal (+ B).
And a collector of a grounded-emitter transistor 88 provided in the output circuit 83. Further, a warning lamp 89 that is turned on when an abnormality is detected is provided on an instrument panel (not shown) in the driver's seat, and the warning lamp 89 is also provided on the battery terminal (+ B) and the grounded-emitter transistor 90 provided in the output circuit 83. Is connected between the collector and. The transistor 88 of the output circuit 83,
The base of 90 is connected to the output port of the microcomputer 75, which is a control means, via resistors 91 and 92, respectively.

On the other hand, the output transistor 8 of the drive circuit 84
The collector (output terminal) of 7 is also connected to the input terminal of the abnormality detection circuit 85. The abnormality detection circuit 85 is configured to change the output voltage by turning on / off the PNP type transistor 93 and the NPN type transistor 94 according to the input voltage. Specifically, the pull-down resistor 95 is connected between the input terminal of the abnormality detection circuit 85 and the ground terminal, whereby the resistors 96 and 97, the diode 98 and the pull-down resistor are connected between the battery terminal (+ B) and the ground terminal. The circuit configuration has resistors 95 connected in series. The PNP transistor 93 is
The emitter is connected to the battery terminal (+ B), and the base is connected between the resistors 96 and 97.

The collector of this PNP type transistor 93 is connected to the base of an NPN type transistor 94 via a resistor 99. A resistor 100 and a capacitor 101 are connected in parallel between the base of the transistor 94 and the ground terminal. This transistor 94
Has its emitter grounded and its collector anomaly detection circuit 85
Is connected to the output terminal of the DC power supply terminal, and the collector is connected to the + 5V DC power supply terminal via the pull-up resistor 102.

Abnormality detection circuit 85 configured as described above
Output level changes according to ON / OFF of the SPV relay 86 and ON / OFF of the output transistor 87 of the drive circuit 84, as shown in FIG. That is, when the output transistor 87 of the drive circuit 84 is in the off state and the SPV relay 86 is in the on state, the battery voltage (+ B) is SP.
Solenoid coil 3 of V relay 86 and electromagnetic spill valve 30
1 is applied to the input terminal of the abnormality detection circuit 85.
In this state, the base potential of the transistor 93 in the preceding stage is kept at the same potential (+ B) as the emitter potential, so that the transistor 93 is kept in the off state, and the transistor 94 in the latter stage is also kept in the off state. The output level of the abnormality detection circuit 85 is maintained at the high level (H).

When the SPV relay 86 is turned off while the output transistor 87 is in the off state, the battery voltage (+ B) is not applied to the input terminal of the abnormality detection circuit 85 from the outside and the battery is connected to the input terminal. The pull-down resistor 95 lowers the potential of the input terminal. Between this input terminal and the battery terminal (+ B), resistors 96 and 97 are connected.
And the diode 98 are connected in series, and the resistor 96 is connected between the emitter and the base of the transistor 93 at the preceding stage. Therefore, when the potential of the input terminal is lowered by the pull-down resistor 95, the potential between the emitter and the base of the transistor 93 at the preceding stage is reduced. A potential difference is generated by the resistor 96, and the transistor 93 is turned on. As a result, a voltage is applied to the base of the transistor 94 in the subsequent stage to turn on the transistor 94,
The output terminal of the abnormality detection circuit 85 becomes conductive with the GND terminal through the transistor 94, and the output level becomes low level (L).

On the other hand, the output transistor 8 of the drive circuit 84
When 7 is on, the input terminal of the abnormality detection circuit 85 is connected to the GND via the output transistor 87 of the drive circuit 84.
It is in a state of being electrically connected to the terminal. In this state, regardless of whether the SPV relay 86 is on or off, the resistor 9 is placed between the emitter and the base of the transistor 93 in the previous stage of the abnormality detection circuit 85.
6, 97, a potential difference is generated, the transistor 93 is turned on, the subsequent stage transistor 94 is turned on, and the output level of the abnormality detection circuit 85 is maintained at a low level (L).

Next, the flow of the fuel injection control system abnormality diagnosis processing executed by the microcomputer 75 will be described with reference to FIGS. 7 and 8. 7 is a routine for determining whether or not the electromagnetic spill valve (hereinafter abbreviated as "SPV") 30 is abnormal, and FIG. 8 is a routine for determining whether or not the SPV relay 86 is abnormal. Here, the presence / absence of abnormality is shown in FIG.
It is determined by whether or not the relationship shown in is satisfied.

The SPV abnormality determination routine of FIG.
This is executed while the relay 86 is on, and first, step 201
Then, it is determined whether or not the output signal from the microcomputer 75 to the drive circuit 84 is an ON signal (high level signal). If it is an ON signal, the process proceeds to step 202, and the output of the abnormality detection circuit 85 is at a low level. (SPV30 is on)
Is determined. Here, if the output of the abnormality detection circuit 85 is low level, it is confirmed from the relationship shown in FIG. 9 that the output transistor 87 of the drive circuit 84 is on (SPV30 is on), and the routine proceeds to step 205, where S
PV30 is determined to be normal. If the output signal to the drive circuit 84 is an ON signal, step 202
If the output of the abnormality detection circuit 85 is at a high level, the output transistor 87 of the drive circuit 84 is not turned on.
Since the drive circuit 84 has failed and the power supply to the SPV 30 cannot be performed, the process proceeds to step 204.
The SPV 30 is determined to be abnormal.

On the other hand, when it is determined in step 201 that the output signal to the drive circuit 84 is the off signal (low level signal), the process proceeds to step 203, and the output of the abnormality detection circuit 85 is low level (SPV30). Is ON) is determined. Here, if the output of the abnormality detection circuit 85 is high level instead of low level, the output transistor 87 of the drive circuit 84 is turned off (S) from the relationship shown in FIG.
PV30 is turned off), step 20
5, the SPV 30 is determined to be normal. If the output of the abnormality detection circuit 85 is low level in step 203 even though the output signal to the drive circuit 84 is an off signal, the output transistor 87 of the drive circuit 84 is short-circuited or the harness is short-circuited. Failure of SPV
Since energization to 30 is in a state where it cannot be stopped, the routine proceeds to step 204, where the SPV 30 is determined to be abnormal.

SP by this SPV abnormality determination routine
When an abnormality in V30 is detected, immediately SPV relay 86
Is turned off to cut off the power supply to the SPV 30, and the bypass throttle valve 53 of the intake throttle mechanism 58 is fully closed to stop the diesel engine 12 for fail-safe, and the warning lamp 89 is turned on to turn on the driver. To warn.

However, before the SPV 30 abnormality is detected, if the SPV relay 86 is out of control due to contact fusion, signal line short-circuiting, etc., even if the SPV 30 abnormality is detected, the SPV relay 86 will not be activated. Since it cannot be turned off, the power supply to the SPV 30 cannot be cut off.

Therefore, in this embodiment, the SPV shown in FIG.
The OFF operation of the SPV relay 86 is pre-checked by the relay abnormality determination routine. SPV relay 86 is SPV
Since the SPV relay 86 is normally kept in the ON state to supply power to the SPV 30, it is possible to turn OFF the SPV relay 86 in advance when power supply to the SPV 30 is unnecessary, for example, when the engine is stopped. In the SPV relay abnormality determination routine of FIG. 8, the OFF operation of the SPV relay 86 is preliminarily checked in the following manner while the engine is stopped from when the ignition switch 78 (IG) is turned on to when the engine is started. An example of the output waveform of each part at this time is shown in FIG.

Immediately after the ignition switch 78 is turned on, the processing of the SPV relay abnormality determination routine of FIG. 8 is started. First, in step 211, it is determined whether or not the engine is being stopped (that is, before the engine is started), and the engine is stopped. If not, the process proceeds to step 212 to maintain the SPV relay 86 in the ON state, and in step 213, the drive signal is output from the microcomputer 75 to the drive circuit 84 to normally control the SPV 30.

On the other hand, if the engine is stopped at step 211, the routine proceeds to step 214, at which the SPV relay 86 is turned off and the power supply to the SPV 30 is cut off.
The operation of 30 is stopped. In the next step 215, SP
In order to confirm whether or not the V relay 86 is actually turned off, it is determined whether or not the output of the abnormality detection circuit 85 is at the low level. If the output is at the low level, S is determined from the relationship shown in FIG.
Since it can be confirmed that the PV relay 86 is off, step 21
7, the SPV relay 86 is determined to be normal, and in the following step 218, the SPV relay 86 is returned to the ON state.

On the other hand, when the output of the abnormality detection circuit 85 is determined to be high level in step 215, it is confirmed from the relationship shown in FIG. 9 that the SPV relay 86 is in the ON state (disabled). , Go to step 216, S
The PV relay 86 is determined to be abnormal. In this case, the warning lamp 89 is turned on to warn the driver.

In the embodiment described above, the SPV is set between the time when the ignition switch 78 is turned on and the time when the engine is started.
Although the OFF operation of the relay 86 is checked in advance, the driver often performs the operation of turning on the ignition switch 78 to start the engine continuously. Therefore, the time from turning on of the ignition switch 78 to starting the engine is long. May be short.

Therefore, in a system in which the main relay 60 is kept in the ON state for a while (eg, for 2 seconds) after the ignition switch 78 is turned off and the power supply to the ECU 61 is continued for a while, the main switch 60 is turned off and then the main switch 60 is turned on. SPV before relay 60 turns off
The OFF operation of the relay 86 may be checked. In this case, immediately after the ignition switch 78 is turned off, the SPV relay abnormality determination routine of FIG. 8 is executed to check the OFF operation of the SPV relay 86, and the warning to the driver is stored in the backup RAM 71. At the next driving, the warning lamp 89 is turned on to warn the driver. FIG. 3 shows the output waveform of each part when the OFF operation of the SPV relay 86 is checked immediately after the ignition switch 78 is turned off.

Further, the check of the OFF operation of the SPV relay 86 is not limited to the case where it is performed while the engine is stopped. Even when the engine is operating, it is unnecessary to supply power to the SPV 30, that is, the drive circuit 84. Output transistor 87
It is also possible to check the off operation of the SPV relay 86 when is off. Here, the output transistor 87 of the drive circuit 84 is turned off during the engine operation (SPV3
0 is turned off) during the fuel cut control, for example, when traveling on a long downhill or when the engine brake is applied. Therefore, while the engine is running,
When the output transistor 87 of the drive circuit 84 is turned off by the fuel cut control, the off operation of the SPV relay 86 may be appropriately checked.

In the above embodiment, the SPV relay 86 is used as the opening / closing means for cutting off the power supply to the SPV 30 when the fuel injection control system is abnormal. However, another switching element such as a transistor may be used. good. Also,
In the above-mentioned embodiment, the warning lamp 89 is adopted as a warning means for warning the driver in the event of an abnormality. However, a warning may be displayed on a display panel such as a liquid crystal panel, or a sound or a warning sound is generated in the event of an abnormality. It may be allowed to.

In the above embodiment, the electromagnetic spill valve (S
Although the fuel injection amount is controlled by the PV 30, the present invention can be applied to a system in which the position of the spill ring is feedback-controlled by the linear solenoid to control the fuel injection amount.

[0043]

As is apparent from the above description, according to the configuration of claim 1 of the present invention, the fail-safe opening / closing means of the fail safe opening / closing means is provided when the output transistor of the drive circuit is in the off state (fuel injection stopped state). Since an abnormality detection circuit that outputs a voltage level signal according to ON / OFF is provided, in addition to detecting an abnormality in the fuel injection control system, the OFF operation of the fail-safe opening / closing means can be checked in advance. The safety can be improved.

Further, in claim 2, by connecting a pull-down resistor between the input terminal of the abnormality detection circuit and the ground terminal, the abnormality detection circuit outputs a signal of a voltage level according to ON / OFF of the opening / closing means. By doing so, it is possible to check the opening / closing means in advance with an extremely simple circuit configuration.

Further, according to the third aspect, since the off operation of the opening / closing means is checked in advance when the output transistor of the drive circuit is in the off state, the opening / closing means can be checked in advance without interrupting the fuel injection control. It can be carried out. Moreover, since the warning means is activated in the event of an abnormality, the driver can be warned in the event of an abnormality.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram of a main part showing an embodiment of the present invention.

FIG. 2 is a timing chart showing output waveforms of respective parts in a case where an OFF operation of an SPV relay is preliminarily checked between an ignition switch being turned on and an engine being started.

FIG. 3 is a timing chart showing output waveforms of respective parts when the OFF operation of the SPV relay is checked between the time when the ignition switch is turned off and the time when the main relay is turned off.

FIG. 4 is a block diagram of the entire control system.

FIG. 5 is a block diagram showing an internal configuration of an ECU.

FIG. 6 is a configuration diagram of the entire system.

FIG. 7 is a flowchart showing a processing flow of an SPV abnormality determination routine.

FIG. 8 is a flowchart showing a processing flow of an SPV relay abnormality determination routine.

FIG. 9: ON / OFF of output transistor of drive circuit, S
It is a figure which shows the relationship between ON / OFF of a PV relay and the output level of an abnormality detection circuit.

[Explanation of symbols]

11 ... Injection pump, 12 ... Diesel engine, 16 ...
Fuel feed pump, 28 ... Fuel injection nozzle, 29 ... Spill passage, 30 ... Electromagnetic spill valve (SPV), 33 ... Timer device, 38 ... Timing control valve, 41 ...
Glow plug, 52 ... Bypass passage, 53 ... Bypass throttle valve, 54, 55 ... Vacuum switching valve (VS
V), 56 ... Actuator, 57 ... Throttle valve, 58 ... Intake throttle mechanism, 60 ... Main relay, 61 ...
Electronic control unit (ECU), 70 ... Battery, 75 ... Microcomputer (control means), 78 ... Ignition switch, 80 ... Starter switch, 84 ... Drive circuit,
85 ... Abnormality detection circuit, 86 ... SPV relay (opening / closing means), 87 ... Output transistor, 89 ... Warning lamp (warning means), 95 ... Pull-down resistance.

Claims (3)

[Claims] 1. A switching means for shutting off power supply to a fuel injection device when a fuel injection control system of a diesel engine is abnormal, a drive circuit for driving the fuel injection device, and a control circuit for controlling the opening / closing means and the drive circuit. Control means and on / off of the opening / closing means connected to the output terminal of the drive circuit, when the output transistor of the drive circuit is in the off state.
An abnormality detection circuit that outputs a voltage level signal according to the off state, and whether there is an abnormality in the opening and closing means based on the output from the control means to the opening and closing means and the drive circuit and the output of the abnormality detection circuit. A fuel injection control system abnormality diagnosing device for a diesel engine, which is configured to determine whether or not there is an abnormality in the fuel injection control system. 2. The abnormality is connected when a pull-down resistor is connected between an input terminal of the abnormality detection circuit and a ground terminal and the output transistor of the drive circuit is in an off state and the opening / closing means is in an off state. The fuel injection control system abnormality diagnosis device for a diesel engine according to claim 1, wherein the input potential of the detection circuit is lowered by the pull-down resistor. 3. When an output transistor of the drive circuit is in an off state, an off signal is output from the control means to the opening / closing means to determine whether or not the opening / closing means has an abnormality, and when the abnormality occurs, the warning means is activated. Claim 1 characterized by the above.
Alternatively, the fuel injection control system abnormality diagnosis device for a diesel engine according to item 2.