JPH0932618A - Fuel injection control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine shifting of a detecting position within an ordinary control range to ensure designated engine performance and also improve the operability by smooth control switching, by controlling fuel injection quantity according to a detection value of one of first and second rack position sensors that is determined to be normal. SOLUTION: A fuel injection control device comprises a fuel injection quantity control means 8 for controlling an actuator and feedback controlling fuel injection quantity according to a detection value of first or second rack position sensors 3, 4. Further, the device comprises an abnormality determining means 6 for determining whether the first and second rack position sensors 3, 4 are abnormal or not according to the detection values of the first or second rack position sensors and the output of an operating condition detecting means. Further, the device comprises a position detection value switching means 7 for controlling fuel injection quantity in the fuel injection quantity control means 8 according to the detection value of one of the first and second rack position sensors 3, 4 that is determined to be normal. Thus, only the software is changed and the cost will not be increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for a diesel engine.

[0002]

2. Description of the Related Art A fuel injection control device of this kind is shown in FIG. This is a control rack (not shown) slidably provided in the injection pump body 1.
Is driven by an actuator (not shown) of the governor 2 to adjust the fuel injection amount.

The actuator is controlled by a drive signal from the control unit 5 so that the fuel injection amount is optimum according to the engine operating condition.

Further, the control unit 5 inputs two detection signals of the main rack sensor 3 and the subrack sensor 4 for detecting the position of the control rack to the CPU, and usually feeds back with the detection signal of the main rack sensor 3. Have control.

When the main rack sensor 3 fails, the subrack sensor 4 is switched, and when both the main and sub sensors fail, the target engine speed is switched to open loop control.

After the main rack sensor 3 and the subrack sensor 4 are judged to be faulty, the engine is temporarily stopped,
When the occupant operates the key OFF->ON-> START, the control is shifted to the next control.

[0007]

However, in the electronic governor system in which the rack position detection is duplicated as described above, since only the failure due to the disconnection or short circuit of the sensor is diagnosed, the pseudo contact of the connector terminal or the harness etc. If the detection position shifts within the normal control range due to the above, there is a problem that the engine performance is deteriorated because the control is performed with the shift.

Further, if it is determined that the sensor has failed, the engine is once stopped during the transition to the next control, which causes a problem of poor drivability.

Incidentally, Japanese Patent Laid-Open No. 4-214940 discloses that
The signal values generated from a plurality of sensors are compared with each other to check whether the function of the sensor is normal or not according to whether it is within a predetermined tolerance range, and based on that, malfunction of at least one of the sensors Techniques for detecting the are disclosed.

According to this publication, the failure due to the disconnection or short circuit of the sensor cannot be diagnosed, and the deviation of the detection position within the normal control range is recognized and the control of the normal sensor is not continued. The above-mentioned problems are included.

Therefore, an object of the present invention is to provide a fuel injection control device capable of determining a deviation of a detected position within a normal control range to secure a predetermined engine performance and improving drivability by smooth control switching. To do.

[0012]

A fuel injection control device according to the present invention is slidably provided on a pump body and engaged with a pump element in the pump body to rotationally displace the pump element. A control rack capable of adjusting the amount of fuel injection, an actuator for driving the control rack, first and second rack position sensors for detecting the position of the control rack, and an operating state detecting means for detecting an operating state of the engine. And a fuel injection amount for controlling the actuator so that the fuel injection amount is set according to the output of the operating state detection means and performing feedback control based on the detection value of at least one of the first and second rack position sensors. Of the control means, the detection values of the first and second rack position sensors, and the operating state detection means. Abnormality determining means for determining whether or not the first and second rack position sensors are abnormal based on the force, and one of the first and second rack position sensors determined to be normal by the output of the abnormality determining means. Position detection value switching means for controlling the fuel injection amount in the fuel injection amount control means based on the detection value.

The operating state detecting means includes at least an accelerator position sensor for detecting the amount of depression of an accelerator pedal of an occupant, and the abnormality determining means calculates a deviation between detection values of the first and second rack position sensors. A first abnormality determination unit that determines whether the deviation exceeds a predetermined amount and a virtual operation state based on the output of the accelerator position sensor when the first abnormality determination unit determines that the deviation exceeds the predetermined amount The first and second driving conditions are compared with the actual driving condition based on the output of the driving condition detecting means other than the accelerator position sensor.
It is preferable to include the second abnormality determination unit that determines whether or not the rack position sensor is normal, because the deviation of the detection position within the normal control range can be easily determined.

The operating state detecting means includes a rotation speed sensor and a load sensor for detecting an engine rotation speed and an engine load of the engine, respectively, and the second abnormality determining section is detected by the rotation speed sensor and the load sensor. When the abnormality of the first and second rack position sensors is determined based on the engine speed and the engine load, the determination in a certain wide operating range can be reliably performed, which is preferable.

The second abnormality determining section compares the virtual engine speed and virtual engine load that change based on the output of the accelerator position sensor with the actual engine speed and the actual engine load detected by the operating condition detecting means. When it is determined whether the first and second rack position sensors are normal, it is possible to easily and surely make a determination in a certain wide operating range, which is preferable.

The abnormality determining means controls the actuator so that the fuel injection amount is set to no injection for a set period when at least the first rack position sensor is determined not to be normal by the second abnormality determining section, and the setting is performed. It is preferable to include a third abnormality determination unit that determines whether or not there is an abnormality in the first and second rack position sensors within the period, because the determination can be reliably performed in all operating ranges.

The position detection value switching means is configured to inject fuel into the fuel injection amount control means on the basis of the detection value of the first and second rack position sensors which is determined not to be abnormal by the third abnormality determining portion. Control is performed, and when it is determined that both the first and second rack position sensors are abnormal, switching to open loop control by the target engine speed that does not use the position detection value of the control rack It is suitable in terms of safety and safety.

The position detection value switching means determines the fuel injection amount of the fuel injection amount control means when at least the first rack position sensor is determined not to be normal by the second abnormality determination part of the abnormality determination means. It is preferable in terms of drivability to switch the position detection value of the control rack used for control to the detection value of the second rack position sensor.

The position detection value switching means changes the position detection value of the control rack used for controlling the fuel injection amount in the fuel injection amount control means from the detection value of the first rack position sensor to that of the second rack position sensor. When switching to use the detection value, the control rack is controlled from the engine speed and the no-load rack position at the time of switching to a rack position corresponding to the no-load accelerator opening, and the control rack corresponds to the actual accelerator position. It is preferable to gradually increase or decrease to the actual rack position with an appropriate gradient because the switching shock can be eliminated.

A failure determination means for determining whether or not the detection values of the first and second rack position sensors exceed the normal control range based on the detection values detected by the first and second rack position sensors, The position detection value switching means controls the fuel injection amount in the fuel injection amount control means on the basis of the detection value of one of the first and second rack position sensors which is determined not to be defective by the failure determination means. Further, when it is determined that both the first and second rack position sensors are out of order, switching to open loop control based on the target engine speed that does not use the position detection value of the control rack will improve drivability and safety. It is suitable in terms of aspect.

According to the above construction, the deviation of the detection position of the control rack can be judged and the abnormality judgment can be backed up without stopping the engine, thereby improving the engine performance and drivability.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a fuel injection control device according to the present invention will be described in detail below with reference to the accompanying drawings.
1 is a schematic configuration diagram of the first embodiment, FIG. 2 is a flow chart showing the control operation of the control unit, FIG. 3 is a flow chart of the control switching, and FIG. 4 is a graph showing a transition of the accelerator opening after the control switching. is there.

As shown in FIG. 1, the actuator (not shown) of the governor 2 for driving the control rack (not shown) in the injection pump body 1 is brought into the engine operating state by the drive signal from the control unit 5A. The fuel injection amount is controlled according to the optimum fuel injection amount.

The control unit 5A inputs two detection signals of the main rack sensor 3 and the subrack sensor 4 for detecting the position of the control rack, and normally performs feedback control with the detection signal of the main rack sensor 3. .

Further, in this embodiment, the control unit 5A includes a rotational speed sensor, a load sensor, an accelerator position sensor, etc. for detecting the detection values of the main rack sensor 3 and the subrack sensor 4 and the engine operating state. Abnormality determination means 6 for determining whether or not the main rack sensor 3 and the subrack sensor 4 are abnormal based on the output.
And the position detection value switching means 7 for outputting only the detection value of the main rack sensor 3 or the subrack sensor 4 which is determined to be normal by the output of the abnormality determination means 6, and the position detection value switching means 7 Fuel injection amount control means 8 for controlling the fuel injection amount on the basis of the detected value from the engine and the output of the rotation speed sensor, the load sensor, the accelerator position sensor, etc. for detecting the engine operating state.

Next, the control operation of the control unit 5A will be described in detail with reference to the flowchart of FIG. Note that P1 to P11 in FIG. 2 are operation steps.

First, in step P1, it is determined whether or not the detected value (rack position signal) of the main rack sensor 3 is outside the normal control range (so-called failure), and if the determination is negative, step P2.
On the other hand, it is determined whether the detection value of the subrack sensor 4 is outside the normal control range or not. If the determination is possible, it is similarly determined in step P3 whether the detection value of the subrack sensor 4 is outside the normal control range.

If the determination is negative in step P3, the control switching by the subrack sensor 4 is performed in step P4, while if the determination is acceptable, the open loop control based on the target engine speed is performed in step P5.

If the determination is negative in step P2, it is determined in step P6 whether the deviation between the detection values of the main rack sensor 3 and the subrack sensor 4 exceeds a predetermined amount (for example, 1 mm). If yes, the control by the main rack sensor 3 is continued in step P7.

If the determination is negative in step P6, the control by the main rack sensor 3 is continued in step P7. If the determination is acceptable, it is determined in step P8 whether the detected values of both sensors are normal or not. Determines by detecting changes in engine speed and engine load.

For example, when it is detected that the engine speed and the engine load increase or decrease at the same time even though the accelerator opening has not changed, it can be determined that the operation is not normal. That is, there is the relationship shown in FIG. 4 between the engine speed and the engine load when the accelerator opening is constant, and therefore, it can be determined that the engine speed is not normal if it is off the line in FIG. .

If the determination is possible in step P8 (the main rack sensor 3 or both the main rack sensor 3 and the subrack sensor 4 are normal), the control by the main rack sensor 3 is continued in step P7, while the determination is made. No (main rack sensor 3 is abnormal or cannot be determined), the actuator of the governor 2 is temporarily pulled down (fuel cut) in step P9.

Next, in step P10, it is determined whether or not the detected value of the main rack sensor 3 is outside the allowable range (so-called abnormality). If the determination is negative, the control by the main rack sensor 3 is continued in step P7. If the determination is possible, it is determined in step P11 whether the detection value of the subrack sensor 4 is outside the allowable range.

If the determination is negative in step P11, the control switching by the subrack sensor 4 is performed in step P4, while if the determination is acceptable, open loop control based on the target engine speed is performed in step P5.

As described above, in the present embodiment, each control switching is performed without stopping the engine, but at the time of this switching, in order to eliminate a shock or the like and realize a smooth switching, as shown in FIGS. 3 and 4. In addition to controlling the control rack from the engine speed at the time of switching and the no-load rack position to the rack position corresponding to the no-load accelerator opening,
The control rack is gradually increased or decreased with an appropriate gradient to the actual rack position corresponding to the actual accelerator opening.

FIG. 5 is a flow chart showing the control operation of the second embodiment of the control unit.

This is step P8 in the previous embodiment.
Determines whether the detection values of the main rack sensor 3 and the subrack sensor 4 are normal by detecting changes in the engine speed and engine load. If the determination is possible, the main rack sensor 3 controls in step P7. On the other hand, if the determination is negative, the control of the subrack sensor 4 is immediately switched in step P4 without pulling down the actuator of the governor 2 as in the previous embodiment.

According to this embodiment, the same effect as the previous embodiment can be obtained in most of the driving range.

[0039]

As described above, according to the present invention, the following effects can be obtained. (1) A predetermined engine performance can be secured because the deviation of the detection position of the rack position sensor can be determined and backed up. (2) The engine is not stopped while the vehicle is running, and smooth control switching is possible, which prevents deterioration of drivability. (3) Since only the software is changed, there is almost no cost increase and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of a fuel injection control device according to the present invention.

FIG. 2 is a flowchart showing the control operation of the control unit.

FIG. 3 is likewise a flowchart of control switching.

FIG. 4 is a graph showing a transition of an accelerator opening degree after control switching.

FIG. 5 is a flowchart showing the control operation of the second embodiment of the control unit.

FIG. 6 is a schematic configuration diagram of a conventional fuel injection control device.

[Explanation of symbols]

 1 injection pump main body 2 governor 3 main rack sensor 4 subrack sensor 5A control unit 6 abnormality determination means 7 position detection value switching means 8 fuel injection amount control means

Claims (9)

[Claims] 1. A control rack which is slidably provided on a pump main body and which is engaged with a pump element in the pump main body to adjust the fuel injection amount by rotationally displacing the pump element, and the control rack. Actuator to drive, first to detect the position of the control rack respectively
And a second rack position sensor, an operating state detecting means for detecting an operating state of the engine, and controlling the actuator so that the fuel injection amount is set according to the output of the operating state detecting means. Fuel injection amount control means for performing feedback control based on the detection value of at least one of the two rack position sensors, the first and second fuel injection amount control means based on the detection values of the first and second rack position sensors, and the output of the operating state detection means. Two
An abnormality determining means for determining whether or not the rack position sensor is abnormal, and an output of the abnormality determining means, based on a detection value of one of the first and second rack position sensors determined to be normal, a fuel injection amount control means And a position detection value switching means for controlling the fuel injection amount in the fuel injection control device. 2. The operating state detecting means includes at least an accelerator position sensor that detects the amount of depression of an accelerator pedal of an occupant, and the abnormality determining means includes a detection value of each of the first and second rack position sensors. A first abnormality determination unit that determines a deviation and determines whether the deviation exceeds a predetermined amount, and an output of the accelerator position sensor when the first abnormality determination unit determines that the deviation exceeds a predetermined amount Second abnormality determination for determining whether or not the first and second rack position sensors are normal by comparing a virtual operating state based on the above with an actual operating state based on an output of the operating state detecting means other than the accelerator position sensor. The fuel injection control device according to claim 1, further comprising: 3. The operating condition detecting means includes a rotation speed sensor and a load sensor for respectively detecting an engine rotation speed and an engine load of the engine, and the second abnormality determining section includes the rotation speed sensor, and The fuel injection control device according to claim 2, wherein an abnormality of the first and second rack position sensors is determined based on an engine speed and an engine load detected by the load sensor. 4. The virtual engine rotation and virtual engine load that change based on the output of the accelerator position sensor, and the actual engine speed and actual engine load detected by the operating state detection means, by the second abnormality determination unit. 4. The fuel injection control device according to claim 2, wherein the fuel injection control device determines whether or not the first and second rack position sensors are normal. 5. The abnormality determining means controls the actuator so that the fuel injection amount is set to no injection for a set period when at least the first rack position sensor is determined not to be normal by the second abnormality determining section. The fuel injection control device according to claim 2, further comprising: a third abnormality determination unit that determines whether or not there is an abnormality in the first and second rack position sensors within the set period. 6. The position detection value switching means in the fuel injection amount control means is based on a detection value of one of the first and second rack position sensors which is determined not to be abnormal in the third abnormality determination section. Controlling the fuel injection amount, and switching to open loop control by the target engine speed that does not use the position detection value of the control rack when it is determined that both the first and second rack position sensors are abnormal. The fuel injection control device according to claim 5. 7. The fuel injection in the fuel injection amount control means, wherein the position detection value switching means determines that at least the first rack position sensor is not normal in the second abnormality determination part of the abnormality determination means. The fuel injection control device according to claim 2, wherein the position detection value of the control rack used for controlling the amount is switched to the detection value of the second rack position sensor. 8. The position detection value switching means changes the position detection value of the control rack used for controlling the fuel injection amount in the fuel injection amount control means from the detection value of the first rack position sensor to the second rack. When switching to use the detected value of the position sensor, the control rack is controlled from the engine speed and the no-load rack position at the time of switching to the rack position corresponding to the no-load accelerator opening, and the control rack is moved to the actual accelerator position. The fuel injection control device according to any one of claims 6 to 7, characterized in that the fuel injection control device gradually increases or decreases to an actual rack position corresponding to the position with an appropriate gradient. 9. A failure determination means for determining whether or not the detection values of the first and second rack position sensors exceed the normal control range based on the detection values detected by the first and second rack position sensors. The position detection value switching means includes the fuel injection amount in the fuel injection amount control means based on the detection value of the one of the first and second rack position sensors which is determined not to be broken by the failure judgment means. Control is performed, and when it is determined that both the first and second rack position sensors are out of order, the control is switched to the open loop control based on the target engine speed that does not use the position detection value of the control rack. The fuel injection control device according to any one of claims 1 to 8.