JP3435616B2 - Diagnostic device for diesel engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel engine diagnostic device.

[0002]

2. Description of the Related Art In a diesel engine electronically controlled injection pump, a microcomputer determines a target injection amount according to operating conditions, and the target injection amount and the actual injection amount detected by a control sleeve position sensor are matched. The feedback control of the fuel injection amount is performed by applying the control amount to the actuator for controlling the fuel injection amount.

In this case, there is a method of judging whether the sensor output is in a normal range or not, and determining that the sensor is out of order if the sensor output is out of the normal range for a certain period or longer. (See JP-A-61-164053).

[0004]

However, due to the difference in response characteristics between the sensor signal and the actuator, the failure of the input circuit of the sensor signal, the PID circuit, the microcomputer, etc., the sensor signal and the actuator are fed back during the feedback control of the fuel injection amount. A so-called hunting may occur in which the feedback control signal crosses the normal range with a short cycle (equivalent to 40 Hz, for example). With respect to this hunting, it cannot be determined that a failure has occurred by the above-described failure determination method.

Therefore, it is an object of the present invention to enable determination even in a failure mode in which a sensor signal or a feedback control signal hunts.

[0006]

In [SUMMARY OF first invention, as shown in FIG. 7, the engine control actuator 51, the control <br/> control target value of the actuator 51 in accordance with the operating condition of the engine the Means 53 for calculating a control amount to be applied to the actuator 51 so that the actual control value of the actuator 51 detected by the sensor 52 for detecting the position of the actuator 51 matches. Means 54 for outputting this actuator control amount to the actuator 51
A means 55 for setting a failure determination value for the sensor output of the sensor 52 to be equal to or higher than the upper limit value of the normal range or lower than the lower limit value of the normal range, and the failure determination value set to be equal to or higher than the upper limit value of the normal range. Means for determining a hunting failure when the sensor output crosses a predetermined number of times within a predetermined time or a failure determination value set below the lower limit of the normal range for a predetermined number of times within a predetermined time.

[0007] In the second invention, as shown in FIG. 8, the engine control actuator 51, the control target value of the actuator 51 according to the operating conditions of the engine A
Means 53 for calculating a control amount given to the actuator so that the actually measured control value of the actuator 51 detected by the sensor 52 for detecting the position of the actuator 51 and the actuator control amount are output to the actuator 51. Means 54, means 61 for setting the failure determination value for the actuator control amount to be equal to or higher than the upper limit value of the normal range or lower than the lower limit value of the normal range, and the failure determination value set to be equal to or higher than the upper limit value of the normal range. Means 62 for determining a hunting failure when the control amount crosses a predetermined number of times within a predetermined time or when the actuator control amount crosses a predetermined number of times within a predetermined time for a failure determination value set below the lower limit of the normal range. Provided.

According to a third aspect of the present invention, in the first or second aspect of the invention, the hunting failure determination means samples the sensor output or the actuator control amount at a predetermined cycle shorter than the hunting cycle, as shown in FIG. Means 71, a first accumulating means 72 for accumulating a predetermined value in each predetermined cycle from the time of starting, and a predetermined value in each predetermined cycle, and each time the sampling value crosses a failure determination value. Second integrating means 73 for returning to the initial value
And a means 74 for determining whether the second integrated value by the second integrating means 73 is less than the second determination value or greater than or equal to the second determination value, and the second integrated value is determined as the second integrated value from the determination result. When it is equal to or larger than the judgment value of 2, it is judged that it is a normal time, the means 75 for returning the first integration value by the first integration means 72 to the initial value, and the second integration value is the second judgment value based on the determination result.
If it is less than the first judgment value, it means that when the first integrated value is equal to or larger than the first judgment value, a hunting failure is judged.

In a fourth aspect based on any one of the first to third aspects, the actuator 51 is a control sleeve control actuator, and the sensor 52 is a control sleeve position sensor.

[0010]

[0011]

[0012]

According to a fifth aspect of the invention, in any one of the first to fourth aspects of the invention, the failure determination value is provided with hysteresis.

[0014]

In the first aspect of the invention, a value that can be taken only when a hunting failure occurs is used as a failure determination value, and when the sensor output crosses this failure determination value a predetermined number of times within a predetermined time, and in the second aspect, only when a hunting failure occurs. A hunting failure can be reliably determined by setting a value that cannot be taken as a failure determination value and determining when the actuator control amount crosses this failure determination value a predetermined number of times within a predetermined time.

The operation of the third invention is as follows. Both of the two integrated values increase by a predetermined value at predetermined short intervals from the start. In this case, if hunting does not occur in the sensor output or the actuator control amount, the first integrated value is returned to the initial value at the timing when the second integrated value reaches the second determination value, and thereafter, the second integrated value is reached. Since the value is greater than or equal to the second determination value, the first integrated value maintains the initial value. In addition,
The second integrated value continues to increase thereafter, and is kept at the maximum value after reaching the maximum value, for example.

On the other hand, if hunting suddenly occurs during the feedback control, the sampling value will cross the failure determination value, and the second integrated value is returned to the initial value at this timing, and thereafter, 2 times at every predetermined short period. Both integrated values increase by a predetermined value. In this case, since the second integrated value is returned to the initial value each time the sampling value crosses the failure determination value, the second integrated value does not exceed the second determination value. First and foremost growing
The hunting failure is determined at that timing.

As described above, according to the third aspect of the invention, the sensor output or the actuator control amount is sampled at a predetermined cycle shorter than the hunting cycle, and the first integrated value is integrated by the initial value at each predetermined short cycle from the start. On the other hand, the second integrated value is integrated by the initial value every short predetermined period, and the second integrated value is added every time the sampling value crosses the failure determination value.
Only the integrated value is returned to the initial value, and when the second integrated value is greater than or equal to the second determination value, it is determined to be normal when the second integrated value is compared with the second determination value. with return first integrated value to the initial value, the second integrated value is the second judgment value Not
When it is full, the hunting failure is determined when the first integrated value is equal to or greater than the first determination value. Therefore, it is possible to determine even in the failure mode in which the sensor output or the actuator control amount hunts.

[0018]

When there is no hysteresis in the failure judgment value, it may be erroneously judged that there is a hunting failure due to a bit error. In the fifth invention, however, since the failure judgment value has hysteresis, it is erroneous due to a bit error. The judgment can be avoided.

[0020]

1 shows the details of a fuel injection pump 1. As shown in FIG. In FIG. 1, the fuel injection pump includes a plunger 3 that compresses fuel in a pressurizing chamber 4 while rotating and reciprocating while engaging with a cam roller in an injection pump body 2 that forms a pump housing. On the outer circumference of this plunger 3,
A control sleeve 5 for adjusting the fuel injection amount is slidably fitted by opening and closing a cutoff port 3a formed in the plunger 3, and a rotary solenoid 6 for driving the control sleeve 5 is provided. As the output voltage to the rotary solenoid 6 becomes higher, the control sleeve 5 moves in the direction in which the plunger 3 enters and the fuel injection end timing is delayed and the fuel injection amount increases.

The fuel discharged from the feed pump 7 attached to the pump drive shaft lubricates the inside of the pump and accumulates pressure in the pump chamber 8 from which it is pressurized.
Is sucked into. It should be noted that the feed pump 7 and a timer piston 9 described later are shown in a state of being rotated by 90 ° for the sake of explanation.

In order to control the fuel injection timing, a timer piston 9 is provided as an injection timing control member that moves the phase of the cam roller while engaging with the cam roller that drives the plunger 3. The position of the timer piston 9 is controlled by a timing control valve 10 that controls the flow rate of fuel leaked from the high pressure chamber at one end to the low pressure chamber side, thereby advancing or retarding the fuel injection timing.

A controller 21 is provided to control the fuel injection amount, injection timing, and the like. The controller 21 includes an accelerator opening sensor 22 for detecting an accelerator opening corresponding to an engine load, a rotation speed sensor 23 for detecting a rotation speed of a fuel injection pump, and a cooling water temperature in order to detect an operating condition. Water temperature sensor 24 to detect,
A signal from the fuel temperature sensor 25 that detects the fuel temperature is input. Further, the controller 21 includes a control sleeve position sensor 26 for detecting the position of the control sleeve 5 for detecting the fuel injection amount, and the fuel injection nozzle 2.
Signals from a nozzle lift sensor 28 as an actual injection timing detecting means mounted on the No. 7 for actually measuring the injection timing, a key switch 29 for recognizing an engine start command, and the like are also input.

FIG. 2 shows details of the servo circuit in the fuel injection amount control device.

In the main microcomputer 41, the fuel injection amount characteristic (drive Q map) is searched from the engine speed and the accelerator opening to obtain the basic fuel injection amount, and various corrections are made to this to obtain the target injection amount. The microcomputer output target voltage value UASLMS is calculated by calculating the pump characteristics from the target injection amount and the engine speed. This UAS
The LMS is converted into a duty signal of 1.5 KHz and input to the F-V conversion circuit 42, where it is converted into the target rotary solenoid output voltage UAM1 and the PID circuit 43.
Entered in. The PID circuit 43 also has an input circuit 44.
The actual rotary solenoid output voltage UAIST from is input, and the target rotary solenoid output voltage UAM2 is obtained so that this UAIST matches UAM1.
This UAM2 is converted into a duty signal UAM3 of 250 Hz by the VF conversion circuit 45 and output to the rotary solenoid 6.

On the other hand, the control sleeve position sensor 2
The signal from 6 (actual rotary solenoid output voltage UAIST from the input circuit 44) is input to the sub-microcomputer 46, and the sub-microcomputer 46 determines whether or not the sensor 26 has a failure. For example, UAIST
Is within the normal range, it is determined that the sensor 26 is out of order when the state outside the normal range elapses for a predetermined time.

However, when feedback control of the fuel injection amount is performed by the configuration shown in FIG. 2, the response characteristics of the sensor signal and the actuator (rotary solenoid 6) are different, or each circuit (FV conversion circuit 42, P
A so-called hunting may occur in which the sensor signal crosses the normal range in a short cycle due to a failure of the ID circuit 43, the input circuit 44, the VF conversion circuit 45), the main microcomputer 41, or the like. With the determination method, it cannot be determined that a failure has occurred.

The hunting will be described in more detail with reference to FIG. 5. The full range of the sensor output is 0.7V to 3.5V (the full range of the input circuit 44 is 0.3V to 4.7V), but when hunting occurs. U at a cycle equivalent to 40 Hz
The peak of AIST exceeds 3.5V.

To deal with this, in the present invention, a hunting failure is determined for the actual rotary solenoid output voltage UAIST. Even if the accelerator pedal is periodically depressed, the UAIST waveform becomes periodic,
At this time, UAIST does not exceed the upper limit of the sensor output full range of 3.5 V, and the cycle at this time is 80 m because the accelerator pedal moves slowly.
It is about s and cannot be confused with the case of hunting.

Since hunting also occurs with respect to the target rotary solenoid output voltage UAM2, the hunting failure is also determined with respect to this target rotary solenoid output voltage UAM2.

The contents of this control executed by the sub-microcomputer 46 will be described with reference to the following flow chart.
Since the failure determination method is the same for both UAIST and UAM2, UAIST will be described below.

The flow chart of FIG. 3 is for determining a hunting failure in the output of the control sleeve position sensor, and is executed in a cycle much shorter than the hunting cycle (for example, 4 ms cycle).

At S1 and S4, it is checked whether the ignition key (abbreviated as IGN KEY in the figure) is switched from OFF to ON and whether it is a diagnosis permission condition.
When the ignition key is switched from OFF to ON, it is judged that the engine is starting and the routine proceeds to S2 and S3, where 0 is entered in the hunting monitor counter value (first integrated value) CSPCHK and the flag G2FLG1 is cleared. Further, even when the diagnosis permission condition is not satisfied at the time of not starting, S2, S
Go to 3.

When the ignition key is ON and the start switch is OFF, it means that the diagnosis permission condition is satisfied.
At this time, the maximum value is compared with CSPCHK in S5, and if not the maximum value, CSPCHK is incremented by 1 in S6.

In S7, the normality determination counter value (second integrated value) GM5CNT is calculated. The calculation of GM5CNT will be described with reference to the subroutine of FIG.

In S21, S22, and S23 of FIG. 4, the hunting determination voltage value is set to 3.5 V, and the hunting determination voltage value DGHCSP (= 3.5 V) is set in the variable ROL in order to add hysteresis to the hunting determination voltage value. Then, the hysteresis width HYCS
The value obtained by subtracting P (= 0.4 V) is set as the value of ROL again, and the hunting determination voltage values ROH and ROL are determined by inserting DGHCSP into the variable ROH. As a result, as shown in FIGS. 5 and 6, the position of 3.5 V is ROH and the position of 0.4 V lower than that is RO.
It becomes L.

In S24 and S25, UAIST and ROLL,
By comparison with ROH, it is divided into three cases, <1> UAIST is less than ROL, <2> UAIST is ROL or more and less than ROH, and <3> UAIST is ROH or more. Advances to S26, S27 and S28, in which the normality determination counter value GM5CNT (0 at the time of starting) is set to 0 and the flag G2FLG3 is cleared only when the flag G2FLG3 is in the set state. <3>
If so, the process proceeds to S29, S30, S31, and the flag G
Only when 2FLG3 is in the clear state, the normality determination counter value GM5CNT is set to 0, and the flag G2FLG is set.
Set 3. When <2>, the current situation is maintained.

In S32 and S33, the maximum value is compared with GM5CNT, and when GM5CNT is not the maximum value, GM5C
Increment NT by 1.

As shown in FIG. 5, how the flag G2FLG3 and the normality determination counter value GM5CNT change will be described in detail. is doing. Now one cycle of UAIST (eg from point A to D
(Up to the point), at point A, S26 in FIG.
Since S28, S32, and S33 flow, G2FLG3 is held in the clear state and GM5CNT is incremented. If point B is not reached even after 4 ms,
At S26, S28, S32, S33, G2
GM5CNT is incremented while FLG3 is held in the clear state. This state continues until just before the point B, and at the point B, S29, S30, S31, S32,
Since the flow proceeds to S33, G2FLG3 is switched to the set state, and GM5CNT is returned to 0. After that, until just before the point C, S29, S31, S32, and S33 flow to G2.
FLG3 is held in the set state, and GM5CNT increases. At point C, S26, S27, S28, S
32, S33, G2FLG3 is switched to the clear state, and GM5CNT is returned to 0. After that, until point D, S26, S28, S32, S33 flow to G2F
LG3 is kept in the clear state and GM5CNT increases.

In this way, GM5CNT becomes UAI
Since ST is returned (cleared) to 0 at the timing of crossing ROH and ROL, it becomes a value that cannot be increased when hunting occurs. On the other hand, when hunting does not occur, UAIST does not cross ROL and ROH as shown in FIG. 6, so GM5CNT
Will only increase and will never be reset to zero. That is, in FIG. 4, S24 to S26, S27 to S29,
S31 is a part for determining whether or not there is a condition for clearing GM5CNT by comparing UAIST with ROH and ROL.

After the GM5CNT is calculated in this way, returning to FIG. 3, the GM5CNT is compared with the normal counter clear determination value (second determination value, for example, 7) CSPCNT in S8. CSPCNT is a determination value for clearing the counter value CSPCHK during normal operation, and as shown in FIGS. 5 and 6, the counter value GM5CN
It is specified that T does not reach only during hunting. Therefore, the counter value GM5CNT is the judgment value CSP.
When it becomes more than CNT, it is judged to be a normal time, and S
In step 11, the counter value CSPCHK is returned to 0 to prepare for the next hunting failure determination.

On the other hand, GM5CNT is CSPCN
If it is less than T, there is a possibility of hunting failure, so the routine proceeds to S9, where the counter value CSPCHK and the hunting determination value ( first determination value, eg, 27) CSP.
Compare with CNG. If CSPCHK is greater than or equal to CSPCNG, it is determined that a hunting failure has occurred, and the flag G2FLG1 is set in S10. By setting the flag G2FLG1 in the set state, it is indicated that a hunting failure has occurred in the output of the control sleeve position sensor.

It should be noted that CSPCNG is better than CSPCNT.
The reason for making it larger than is to prevent the GM5CNT from being judged as a hunting failure before it is returned to 0 several times (that is, before experiencing hunting).

The operation of the present invention will now be described with reference to FIGS.

As long as the diagnosis permission condition is satisfied, as shown in FIG. 6, the two counter values CSPCHK and GM5.
Both CNTs increase by 1 every 4ms from the start. In this case, if hunting does not occur in UAIST, the second counter value GM5CNT becomes the second determination value C.
The first counter value CS at the timing when SPCNT is reached
PCHK is returned to 0, and thereafter, the second counter value GM
Since 5CNT becomes the second judgment value CSPCNT or more,
The first counter value CSPCHK keeps the state of 0. The second counter value GM5CNT continues to increase thereafter, and is maintained at the maximum value after reaching the maximum value.

On the other hand, if hunting suddenly occurs at point E during feedback control of the fuel injection amount as shown in FIG. 5, UAIST will cross the hunting determination voltage value ROH, and at this timing the second counter value GM5C
NT is returned to 0, and thereafter, the two counter values GM5CNT and CSPCHK are incremented by 1 every 4 ms.

In this case, the second counter value GM5CNT
Is the hunting determination voltage value ROH, ROLL
Since it is reset to 0 every time it crosses the second counter value G
While M5CNT never exceeds the second judgment value CSPCNT, the first counter value CSPCHK increases and reaches the first judgment value CSPCNG, and at that timing, the flag G2FLG1 changes from the clear state to the set state. Can be switched. That is, a hunting failure is determined and a predetermined fail-safe process is performed after CSPCNG × 4 ms from the timing at which UAIST crosses the hunting determination voltage value ROH due to the occurrence of hunting.

In this way, according to the present invention, the sensor output is sampled at a cycle of 4 ms shorter than the hunting cycle, and the first counter value CSP is collected every 4 ms cycle from the start.
While the CHK is integrated by 1, the second counter value GM5CNT is integrated by 1 every 4 ms cycle, and only the second counter value GM5CNT is set to 0 every time the sampling value crosses the hunting determination voltage values ROH and ROL. This second counter value GM5CN should be returned.
When the second counter value GM5CNT is greater than or equal to the second determination value CSPCNT by comparing T with the second determination value CSPCNT, it is determined to be a normal time and the first counter value CS
PCHK is returned to 0 and the second counter value GM5
When the CNT is less than the second determination value CSPCNT and the first counter value CSPCHK is greater than or equal to the first determination value CSPCNG, it is determined that there is a hunting failure, so determination is made even in a failure mode in which the sensor output hunts. You can

It is not essential to provide hysteresis in the hunting determination voltage value, and ROL = ROH can be set. However, in this case, a hysteresis is provided in the embodiment because it may be erroneously determined that there is a hunting failure due to a bit error.

Further, the hunting determination voltage value may be a voltage value within the normal range, not 3.5V which is the upper limit value of the full range of the sensor output. However, in the embodiment, for safety, the limit value of the normal range is set to 3.5V.

Further, in the embodiment, the feedback control of the fuel injection amount has been described, but the present invention is not limited to this, and as long as hunting occurs in the sensor output or the feedback control signal, the feedback control of the injection timing, the feedback control of the exhaust gas recirculation amount, etc. Can also be applied to.

In the embodiment, the hunting determination is performed by the sub-microcomputer, but it may be performed by the main microcomputer.

[0053]

According to the first aspect of the present invention, a value that can be taken only when a hunting failure occurs is used as a failure determination value, and when the sensor output crosses this failure determination value a predetermined number of times within a predetermined time, and in the second invention, a hunting failure occurs. A value that can be taken only occasionally is set as a failure determination value, and by determining when the actuator control amount crosses this failure determination value a predetermined number of times within a predetermined time,
A hunting failure can be reliably determined.

According to the third aspect of the invention, the sensor output or the actuator control amount is sampled at a predetermined cycle shorter than the hunting cycle, and the first integrated value is integrated with the initial value at each predetermined cycle that is short from the start, while the short value is obtained. The second integrated value is added to the initial value every predetermined period, and only the second integrated value is returned to the initial value each time the sampling value crosses the failure determination value. When the second integrated value is equal to or larger than the second determination value, the first integrated value is returned to the initial value, and the second integrated value is the second determination value. If it is less than the above, it is determined that a hunting failure has occurred when the first integrated value is equal to or greater than the first determination value. Therefore, it is possible to determine even in a failure mode in which the sensor output or the actuator control amount hunts.

[0055]

When there is no hysteresis in the failure determination value, it may be erroneously determined that there is a hunting failure due to a bit error. In the fifth invention, however, since the failure determination value has hysteresis, it is erroneous due to a bit error. The judgment can be avoided.

[Brief description of drawings]

FIG. 1 is a detailed view of a fuel injection pump.

FIG. 2 is a control block diagram of a fuel injection amount.

FIG. 3 is a flowchart for explaining determination of hunting failure of sensor output.

FIG. 4 is a flowchart for explaining calculation of a normality determination counter value GM5CNT.

FIG. 5 is a waveform diagram when a sensor output hunting failure occurs.

FIG. 6 is a waveform diagram of a normal sensor output.

FIG. 7 is a diagram corresponding to claims of the first invention.

FIG. 8 is a diagram corresponding to claims of the second invention.

FIG. 9 is a diagram corresponding to a claim of the third invention.

[Explanation of symbols]

1 injection pump 5 Control sleeve 6 Rotary solenoid (actuator) 21 Controller 26 Control sleeve position sensor

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F02D 41/22 380 F02D 45/00 364 G01M 15/00

Claims (5)

(57) [Claims] 1. An engine control actuator, a control target value of the actuator according to an operating condition of an engine, and an actually measured control value of the actuator detected by a sensor for detecting the position of the actuator are matched. Means for calculating a control amount given to the actuator, means for outputting the actuator control amount to the actuator, and a failure determination value for the sensor output of the sensor is set to an upper limit value of a normal range or a lower limit value of the normal range or less. And the sensor output has a predetermined failure determination value set below the lower limit of the normal range when the sensor output crosses the failure determination value set above the upper limit of the normal range a predetermined number of times within a predetermined time. It is specially equipped with means for judging a hunting failure when it crosses a predetermined number of times within the time. A diagnostic device for diesel engines. 2. An engine control actuator, a control target value of the actuator according to an operating condition of the engine, and an actually measured control value of the actuator detected by a sensor for detecting the position of the actuator are matched. Means for calculating a control amount given to the actuator, means for outputting the actuator control amount to the actuator, and a failure determination value for the actuator control amount is set to be equal to or higher than an upper limit of a normal range or equal to or lower than a lower limit of the normal range. And the actuator control amount is a failure determination value set below the lower limit value of the normal range when the actuator control amount crosses the failure determination value set above the upper limit value of the normal range a predetermined number of times within a predetermined time. Hunting failure is determined when a certain number of times is crossed within a predetermined time A diagnostic device for a diesel engine, which is provided with means. 3. The hunting failure determination means means for sampling the sensor output or the actuator control amount at a predetermined cycle shorter than a hunting cycle, and a first integrated value for each predetermined cycle from the start. An integrating means, a second integrating means for integrating a predetermined value in each of the predetermined cycles, and returning to an initial value each time the sampling value crosses a failure determination value; and a second integrating value by the second integrating means. Means for determining whether it is less than the determination value of 2 or greater than or equal to the second determination value; and from the determination result, when the second integrated value is greater than or equal to the second determination value, it is determined to be a normal time, Means for returning the first integrated value by the first integrating means to an initial value, and when the second integrated value is less than the second determination value from the result of the determination, the first integrated value is greater than or equal to the first determination value. hunting Diagnostic device for a diesel engine according to claim 1 or 2, characterized in that it consists of a is disabled and determining means. 4. The diesel engine diagnostic device according to any one of claims 1 to 3, wherein the actuator is a control sleeve control actuator, and the sensor is a control sleeve position sensor. 5. A diagnostic device for a diesel engine according to any one of claims 1, characterized in that a hysteresis is provided the failure determination value to 4.