JPH09112318A - Controller for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of such an engine's behavior as a service man is surprised immediately after forced release of diagnosis results even if the diagnosis results having failure changes to those having no failure during driving. SOLUTION: The diagnosis results of the presence/absence of failure in an engine control means 61 are stored by a storage means 63. According to the diagnosis results, a backup mode operating command is switched to a set condition if the diagnosis results have failure, and to a clear condition if the diagnosis results have no failure. When the backup mode operating command is in the clear condition, control in a normal mode is indicated, and when the backup mode operating command is in the set condition, control in a backup mode in indicated to the engine control means 61 by an indication means respectively. When the stored diagnosis results change from those having failure to those having no failure, switching of the backup mode operating command from the set condition to the clear condition is prohibited from a prohibition means 66.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a control device for a diesel engine.

[0002]

2. Description of the Related Art In automobile diesel engines, fuel injection pumps are becoming electronic. For example, in the case of a distribution type injection pump, an actuator for adjusting a control sleeve position and an actuator for adjusting a timer position are operated in accordance with a command from a microcomputer. Moving (1984)
"Diesel passenger car" published by Grand Prix Publishing Co., Ltd. p.
130-p. 141).

[0003]

By the way, various self-diagnosis is carried out while the engine is in operation, and the diagnosis result is stored. When the diagnosis result is defective, the control in the backup mode is performed in conjunction with this. Is instructed to the engine control means.

Even if the fuel leakage amount in the plunger compression stroke of the injection pump increases due to a decrease in the fuel viscosity of the fuel used, the control sleeve position sensor detects the measured fuel injection amount so that the injection amount does not become insufficient. Feedback control of the fuel injection amount is performed. In this case, the measured fuel injection amount detected by the control sleeve position sensor and the target injection amount calculated by the microcomputer were almost the same until then, but the output suddenly changed due to the disconnection of the control sleeve position sensor. When it does not come out (that is, the measured fuel injection amount becomes the minimum value), the fuel injection amount is greatly increased by the feedback control, which causes a rapid increase in rotation, and the driving feeling is bad especially in the low load range. Become.

On the other hand, in the self-diagnosis, the sensor output falls below the preset lower limit value due to the disconnection of the control sleeve position sensor. Therefore, when the state below this lower limit value continues for a certain period of time, the sensor malfunctions. Is diagnosed and the result is held in the backup RAM. Further, by controlling in the backup mode, when the self-diagnosis result is data indicating that there is a sensor failure, the feedback control of the fuel injection amount described above is prohibited, so that the driving feeling deteriorates due to a sudden increase in rotation. can avoid.

When a vehicle is brought into a service factory under such a sensor failure condition, a service person connects an external tool (for example, a consult) to operate the engine and displays the self-diagnosis result stored during the past operation. It is possible to know that there is a sensor failure by observing it, but to execute the erasure request command for self-diagnosis while operating, in order to cause the symptom at the time of failure again and to confirm by itself. The self-diagnosis result may be forcibly cleared by pressing the button.

In this case, the backup mode is switched to the normal mode in conjunction with the clearing of the self-diagnosis result, and the feedback control of the fuel injection amount is restarted, so that the self-diagnosis erasing request command is executed. Immediately, a sudden increase in rotation will occur.

Also, during normal operation, even when the control sleeve position sensor is erroneously diagnosed as having a failure and then diagnosed as having no failure, the backup mode can be switched to the normal mode. A sudden increase in rotation may occur.

[0009] Therefore, the present invention, immediately after the forced release of the diagnostic result even if the diagnostic result changes from having a failure to no failure during operation by forcibly releasing the diagnostic result in the service factory or re-diagnosing after a misdiagnosis. It is an object of the present invention to prevent engine behavior that would surprise a service person or engine behavior that would surprise a driver immediately after a second diagnosis after a misdiagnosis.

[0010]

In the first invention, FIG.
As shown in, in the normal mode, by giving a control value calculated based on the sensor detection value to the engine control actuator, and in the backup mode, a control value different from the control value in the normal mode is given to the engine control actuator. A means 61 for controlling the engine by giving it, a means 62 for diagnosing the presence or absence of a failure of the engine control means 61, and a means 6 for storing the diagnosis result.
3, a means 64 for switching the backup mode operating command to the set state when the diagnostic result is faulty and to the clear state when the diagnostic result is faulty, and the backup mode operating command in the clear state. In some cases, the control in the normal mode, and when the backup mode operation command is in the set state, means 65 for instructing the engine control means 61 to perform the control in the backup mode; And a means 66 for prohibiting switching of the backup mode operation command from the set state to the clear state in the case of the change to.

According to a second aspect of the present invention, in the first aspect, when the stored diagnostic result has a fault, the fact that the fault is present is output.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the stored diagnosis result indicates no failure and the engine control for the engine control is performed when the switching of the backup mode operation command from the set state to the clear state is prohibited. When the actuator is not in operation (when the engine is stopped, started, or the operation is stopped even during operation), the switching prohibition state is released and the backup mode operation command is switched from the set state to the clear state.

According to a fourth aspect of the present invention, in any one of the first to third aspects of the invention, the diagnostic result storage means 63 associates the diagnostic result with a diagnostic target (eg, sensor, engine control actuator, CPU). Remember.

In a fifth aspect based on the fourth aspect, the backup mode operating instruction switching means 64 switches the backup mode operating instruction corresponding to a diagnosis target.

According to a sixth aspect of the present invention, in the fifth aspect, the backup mode operation command switching prohibition means 66 comprises a memory for instructing switching prohibition corresponding to a diagnosis target.

[0016]

According to the first aspect of the present invention, even if the diagnostic result changes from having a failure to having no failure during operation by forcibly canceling the diagnostic result in the service factory or re-diagnosing after a misdiagnosis, the set state is cleared. Since switching of backup mode operation command of is prohibited and engine control in backup mode is continued, the engine behavior that makes a serviceman surprised immediately after the forced release of the diagnosis result or the operation immediately after the second diagnosis after misdiagnosis is performed. It is possible to prevent engine behavior that would surprise a person.

If the backup mode operation command cannot be switched from the set state to the clear state when the diagnosis result is released, the symptom at the time of failure is caused again during the operation after knowing that there is a failure. However, in the third aspect of the invention, after the diagnosis result is canceled (that is, the diagnosis result is no failure), once the engine is stopped or the engine is restarted, It is possible to re-create the symptom at the time of failure and confirm it.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 10 denotes an engine body of a diesel engine, 11 denotes an intake passage, 12 denotes an exhaust passage, and intake air is supercharged by a turbocharger 13. Reference numeral 14 denotes an exhaust gas recirculation passage. The amount of exhaust gas recirculated to the intake passage 11 is controlled by an exhaust gas recirculation control valve 15. At the time of exhaust gas recirculation, the throttle valve 16 interposed in the intake passage 11 is throttled.

A fuel injection valve 18 for injecting fuel is provided in the combustion chamber 17 of the engine body 1, and fuel from a fuel injection pump 19 is supplied to the fuel injection valve 18. The fuel injection pump 19 synchronizes with the engine speed and the plunger 2
0 operates, the fuel prepressurized by the feed pump 21 is increased in pressure, and the fuel is pressure-fed to the fuel injection valve 18 of each cylinder near the compression top dead center. The fuel injection amount changes depending on the position of the control sleeve 22, and a rotary solenoid (electronic governor) that operates by a signal from the control device 25.
The position of the control sleeve 22 is controlled by 23.

A control device 25 including a microcomputer receives a signal from an accelerator sensor 26 for detecting the accelerator opening and an engine speed signal, and calculates a basic fuel injection amount according to the accelerator opening and the speed. The rotary solenoid 23 is controlled based on this.

In order to correct the basic injection amount and control the exhaust gas recirculation amount, the control device 25 uses signals representing the operating state, such as the accelerator opening and the rotational speed,
A top dead center position signal (also a rotation speed signal) from a sensor (TDC sensor) 27 that detects the top dead center position of the engine, a vehicle speed signal, and a signal from a transmission switch are input. Furthermore, in order to measure the actual fuel injection amount of the fuel injection pump 19, a signal from the sensor 29 that detects the position of the control sleeve and the sensor 30 that detects the fuel temperature, and the needle lift of the fuel injection valve 18 of the engine body 1. Sensor 31, which detects the amount,
A signal from the sensor 32 that detects the engine cooling water temperature is also input. Further, an air flow meter 33 for detecting a mass flow rate of the engine intake air is attached to the intake passage 11, and this intake air signal is also input.

Since the control device 25 controls the fuel injection timing according to the operating condition, the timing control valve 3
5, the pressure applied to the timer piston 36 is changed. Further, the fuel cut valve 37 is closed when the engine is stopped in order to prevent fuel leakage. further,
The negative pressure control valve 34 that controls the driving negative pressure of the exhaust gas recirculation control valve 15 is duty-controlled, and at the same time, the opening degrees of the first solenoid valve 38 and the second solenoid valve 39 that control the driving voltage of the throttle valve 16 are controlled. With these, optimal exhaust gas recirculation is performed according to the operating state in order to reduce NOx.

The control device 25 also includes various sensors for controlling the engine and an actuator for controlling the engine (the rotary solenoid 23 and the timing control valve 35) for adjusting the fuel injection amount and the fuel injection timing while the engine is operating. Alternatively, the CPU itself is subjected to self-diagnosis, and the diagnosis result is backed up in RAM.
The backup mode operation instruction is switched to the set state when there is a failure and to the clear state when there is no failure according to the diagnosis result. Also, the engine is controlled in the normal mode when it is in the clear state. This will be described with reference to the control block diagram of FIG.

In FIG. 2, the failure diagnosis section 41 carries out self-diagnosis when the diagnosis permission condition is satisfied as follows.

Here, the diagnosis target is the accelerator opening TV.
O, control sleeve position CSP, rotation speed Ne (there are two rotation speeds here, the first rotation speed is Ne1,
The second rotation speed is Ne2), the fuel injection amount Qi, and the fuel injection timing Ti.

<1> TVO: Accelerator sensor output is 0.
Since it is in the range of 7V to 3.5V, if it is not in this range, it is determined that the accelerator sensor 26 has a failure such as a disconnection.

<2> CSP: If the sensor output of the control sleeve position sensor 29 is not within the predetermined range, it is determined that the sensor 29 has a failure such as a wire breakage.

<3> Ne1, Ne2: When the signal from the first rotation speed sensor (TDC sensor 27) or the second rotation speed sensor (pump rotation speed sensor 40, see FIG. 1) is not input during operation of the starter motor. It is determined that there is a malfunction in the rotation speed sensor.

<4> Qi: When the difference between the target injection amount (calculated value) and the measured fuel injection amount (detected by the control sleeve position sensor) is equal to or more than a predetermined value for a predetermined time or more, the rotary solenoid 23. It is determined that the CPU or the CPU has a failure.

<5> Ti: Timing when the difference between the target injection timing and the actually measured injection timing (detected by the timer piston position sensor) is equal to or more than a predetermined value during the feedback control of the injection timing for a predetermined time or more. It is determined that the control valve 35 or the CPU has a failure.

When a failure occurs in the control sleeve position sensor 29 of <2>, the rotary solenoid 23 of <4>, or the CPU, the engine speed may rapidly increase. For example, due to a decrease in the fuel viscosity of the fuel used,
The sensor 2 prevents the actual fuel injection amount from becoming insufficient.
When feedback control for matching the actually measured fuel injection amount detected by 9 and the target fuel injection amount is performed, the output of the sensor 29 suddenly stops due to the disconnection of the sensor 29 (that is, the actually measured fuel injection amount is minimum. When it became a value),
Due to the feedback control, the fuel injection amount is greatly increased, which causes a rapid increase in rotation, which deteriorates the driving feeling particularly in the low load region. Similarly, when the rotary solenoid 23 moves to the side where the fuel injection amount increases due to a failure, or when a large target injection amount is suddenly calculated due to a failure of the CPU, a rapid increase in rotation occurs.

The result of the self-diagnosis performed in this manner is stored in the diagnosis result storage unit 4 including a backup RAM for each diagnosis target.
2 is stored, and based on the stored data, even if there is a failure in the diagnosis target, it is output that there is a failure, and the driver's seat display device (for example, a lamp) is output.
43 is turned on. The contents of the backup RAM for storing the diagnosis result are as shown in FIG. 3, for example, and when the control sleeve position sensor 29 is out of order, the diagnosis result is stored as "1". In FIG. 3, "0" represents no failure, and "1" represents failure.

Regarding the display of the failure, even if only the most important one of the diagnostic objects is turned on, or the driver's seat does not have a display device, a separate service tool microcomputer is operated by a special operation of the service person. Data may be transferred to.

Since the above-mentioned diagnoses <1> to <5> are executed in a constant cycle, it may be diagnosed that there is no failure and then there is no failure. At this time,
The storage data of the diagnosis result is changed from "1" to "0".

On the other hand, the backup mode operation command switching section 44 corresponds to the data in the diagnosis result storage section 42 and is in the set state when the diagnosis result has a failure and in the clear state when the diagnosis result has no failure. The backup mode operation command of the command storage unit 45 is switched. The stored contents of the backup mode operation command are shown in FIG. 4 in correspondence with FIG. 3, and in FIG. 3, it is diagnosed that only the CSP has a failure. “1” indicating the set state of the operation command is stored. Note that the diagnosis result is "0" indicating the clear state of the backup mode operation command for the diagnosis target with no failure.

Next, the operation mode instructing section 46 corresponds to the stored data of the backup mode operation command, and when the data is "0", the control in the normal mode is carried out, and when the data is "1". The engine control unit 47 is instructed to perform control in the backup mode.

Here, the control in the normal mode is to give the control value calculated based on the sensor detection value to the engine control actuator to perform the engine control,
The control in the backup mode is to give a control value different from the control value in the normal mode to the engine control actuator to perform engine control. The specific control in the backup mode is as follows.

[1] TVO: Since the accelerator opening cannot be detected, the accelerator opening TVO is set to the initial idle value TV.
After _turning on O _IDLE , TVO is changed as follows according to an idle switch and a full switch (not shown) provided on the accelerator pedal.

A) When the idle switch is ON and the full switch is OFF TVO (current value) ← TVO (previous value) -Δ1 (1) where Δ1: a predetermined value b) When the idle switch is OFF and the full switch is ON TVO ( (Current value) ← TVO (previous value) + Δ2 (2) where Δ2: predetermined value (Δ2 <Δ1) c) When both idle switch and full switch are OFF TVO (current value) ← TVO (previous value) (3) In the case of a), if TVO (current value) <TVO _IDLE , then TVO (current value) = TVO _IDLE .

[2] CSP: Stop feedback control of the fuel injection amount and switch to open loop control.

[3] Ne1 and Ne2: When both the two rotation speed sensors are out of order, the control using the rotation speed (both feedback control and open loop control) is stopped, and the fuel injection timing and the fuel injection are performed according to the point shown in FIG. Control the amount. When only the first rotation speed sensor fails, the rotation speed detected by the second rotation speed sensor is used.

[4] Qi: Stop feedback control of the fuel injection amount and switch to open loop control.

[5] Ti: The feedback control of the fuel injection timing is stopped and the control is switched to the open loop control.

Now, when the vehicle is brought into a service factory or the like, the service person uses an external tool 48 (see FIG. 2).
You can know that there is a failure in the sensor, actuator for engine control, etc. by operating the engine and taking out the self-diagnosis result stored during the past operation. Since the service person himself / herself confirms this by issuing the self-diagnosis deletion request command while operating, conventionally, depending on the diagnosis result, when the self-diagnosis deletion request command is executed while operating, the service There was a case where a sudden rise in rotation occurred, which caused the man to be surprised.

For example, when the self-diagnosis erasure request command is executed during operation in the state where the control sleeve position sensor 29 is broken, the self-diagnosis result data shown in FIG. 3 are all "0" (that is, self-diagnosis). Clear results)
And the memory data of the backup mode operation command shown in FIG. 4 are all returned to “0”.
The feedback control of the fuel injection amount using the output of the sensor 29 is restarted in a state where the failure of the sensor 29 is not eliminated, and the serviceman is surprised as soon as the command for erasing the self-diagnosis is executed. This causes a sudden increase in rotation, which is the cause.

Similarly, during normal operation, when the sensor 29 is erroneously diagnosed as having a failure and then diagnosed as having no failure, the self-diagnosis result is changed from "1" to "0". Accordingly, the memory data of the backup mode operation command is returned to "0", and the feedback control of the fuel injection amount using the output of the sensor 29 is suddenly restarted, which may cause a rapid increase in rotation.

In order to deal with this, the present invention is provided with a backup mode operation command switching prohibition unit 49 in FIG. 2, and in this switching prohibition unit 49, the storage data of the diagnosis result is changed from "1" to "0". In this case (that is, when there is a change from a failure to a failure), the switching of the backup mode operation command from the set state to the clear state is prohibited for the diagnosis target in which a sudden rotation increase that causes the serviceman to be surprised. In this case, whether to permit or prohibit the switching of the backup mode operation command depends on the data in the memory that instructs the inhibition of the backup mode operation command switching. When the contents of this memory are shown in FIG. 6, the diagnosis target is "0" indicating that switching is prohibited only for CSP and Qi.
For other diagnosis targets, "1" indicating the permission of switching is entered.

Further, in the switching prohibition canceling section 51, the switching of the backup mode operating command from the set state to the clear state for the CSP and Qi is prohibited, and the diagnosis result indicates no failure and the start-up detection section 50. When the start time is detected by, release this switching prohibition state,
The backup mode operation command for CSP and Qi is switched from the set state to the clear state.

The operation of the present invention will now be described.

As shown in FIG. 7, the above items <1> to
As described in <5>, when the diagnostic result changes from “0” to “1” for all five diagnostic objects, the backup mode operation command of each diagnostic object is correspondingly “0”. To "1". This is the same as before.

On the other hand, when the self-diagnosis erase request command is executed (or when the sensor 29, the rotary solenoid 23, and the CPU are erroneously diagnosed as having a failure and then diagnosed as having no failure), the diagnostic result is "1". When CSP and Qi change from "0" to "0", the memory data for instructing the switching prohibition of the backup mode operation command is "0" as shown in FIG.
The backup mode operation command for P and Qi is prohibited from switching to "0" and remains "1". Therefore, even if the sensor 29 has a failure due to disconnection or the rotary solenoid 23 or the CPU has a failure. The engine behavior that would surprise the serviceman does not occur immediately after the self-diagnosis result is erased.

If the backup mode operation command cannot be switched to "0" only for CSP and Qi at the time of executing the self-diagnosis erasure request command, the sensor 29, the rotary solenoid 23, and the CPU may be damaged by using an external tool. While driving after knowing that there is a sensor 29,
It is not possible for the rotary solenoid 23 and the CPU to generate a symptom again when the CPU fails, so that the operator cannot check the condition. However, according to the present invention, if the engine is stopped and then restarted after the execution of the self-diagnosis erase request command, the backup mode operation commands for CSP and Qi are generated as shown in FIG. Since it can be switched from "1" to "0" and the symptoms of the sensor 29, the rotary solenoid 23, and the CPU can be regenerated and checked by themselves, there is no problem.

In this way, according to the present invention, even if the diagnosis result changes from the presence of a failure to the absence of a failure during operation due to forced release of the diagnosis result in the service factory or re-diagnosis after misdiagnosis, Switching of the backup mode operation command to the clear state is prohibited, and engine control in the backup mode is continued, so engine behavior that would surprise the serviceman immediately after forcibly releasing the diagnosis result or re-diagnosis after misdiagnosis Immediately after that, it is possible to prevent engine behavior that would surprise the driver.

In the embodiment, the case where the prohibition state of switching the backup mode operation command from the set state to the clear state at the engine start is released and the backup mode operation command is switched from the set state to the clear state has been described. Not limited to this, the engine control actuator may be in operation stop even when the engine is stopped or running.

[0055]

According to the first aspect of the invention, even if the diagnosis result changes from having a failure to not having a failure during operation due to forced cancellation of the diagnosis result in the service factory or re-diagnosis after misdiagnosis,
Switching of the backup mode operation command from the set state to the clear state is prohibited, and engine control in the backup mode is continued. Immediately after the second diagnosis, it is possible to prevent engine behavior that would surprise the driver.

In the third aspect of the invention, after the diagnosis result has changed from having a failure to having no failure, once the engine is stopped or the engine is restarted, the symptom at the time of failure is caused again. You can check it yourself.

[Brief description of the drawings]

FIG. 1 is a control system diagram of a diesel engine according to an embodiment.

FIG. 2 is a control block diagram of a control device 25.

FIG. 3 is a table diagram for explaining the contents of stored data of diagnosis results.

FIG. 4 is a table diagram for explaining contents of stored data of a backup mode operation command.

FIG. 5 is a table showing control contents in a backup mode when both the TDC sensor 27 and the pump rotation speed sensor 40 have a failure.

FIG. 6 is a table diagram for explaining the memory contents that instruct switching prohibition of a backup mode operation command.

FIG. 7 is a table for explaining switching of backup mode operation commands when a diagnosis result changes from no failure to a failure.

FIG. 8 is a table diagram for explaining switching of backup mode operation commands when a diagnosis result changes from having a failure to not having a failure.

FIG. 9 is a table for explaining switching of backup mode operation commands at the time of starting.

FIG. 10 is a diagram corresponding to claims of the first invention.

[Explanation of symbols]

23 Rotary Solenoid (Engine Control Actuator) 25 Control Device 29 Control Sleeve Position Sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location F02D 45/00 376 F02D 45/00 376F

Claims (6)

[Claims] 1. In a normal mode, a control value calculated based on a sensor detection value is given to an engine control actuator, and in a backup mode, a control value different from the control value in the normal mode is given to an engine control actuator. Means for controlling the engine by giving it, means for diagnosing whether or not there is a failure in this engine control means, means for storing this diagnosis result, and corresponding to this stored diagnosis result. A means to switch the backup mode operation command to the set state and to the clear state when there is no failure, and to control in the normal mode when the backup mode operation command is in the clear state, and to backup when the backup mode operation command is in the set state. Mode control is the engine control Means for instructing the means, and means for prohibiting switching of the backup mode operation command from the set state to the clear state when the stored diagnostic result changes from the presence of a failure to the absence of a failure. Diesel engine controller. 2. The diesel engine control device according to claim 1, wherein when the stored diagnostic result indicates a failure, the failure output is output. 3. The switching prohibition state when the stored diagnostic result indicates that there is no failure and the engine control actuator is not operating in the switching prohibition state of the backup mode operation command from the set state to the clear state. The control device for the diesel engine according to claim 1 or 2, wherein the backup mode operation command is switched from the set state to the clear state by canceling the state. 4. The diagnostic result storage means stores a diagnostic result in correspondence with a diagnosis target.
The diesel engine control device described in any one of the above. 5. The control device for a diesel engine according to claim 4, wherein the backup mode operation command switching means switches the backup mode operation command in accordance with a diagnosis target. 6. The control device for a diesel engine according to claim 5, wherein said backup mode operation command switching prohibition means comprises a memory for instructing switching prohibition in correspondence with a diagnosis target.