JPH08312391A - Accelerator opening sensor trouble diagnosing method - Google Patents

Abstract

PURPOSE: To make it able to perform an accurate diagnosis of trouble in an accelerator opening sensor by diagnosing that there is trouble with this accelerator opening sensor at a time when an idle switch is turned on, and this sensor outputs a value out of the range being allowable as its output in time of idling and further a speed sensor's output indicates a zero speed. CONSTITUTION: At the time of diagnosing trouble with an accelerator opening sensor by a controller, first of all, a fact of whether output of this accelerator opening sensor is large than an extent of accelerator opening maximum allowable output or not is checked, and when it is YES, at this stage, this sensor 8 is so diagnosed that it is out of order. On the other hand, when it is NO, whether a signal out of an idle switch 9 is ON or not is checked, and when it is YES, likewise a fact of whether the output of the sensor 8 is a value out of the range being allowable as the output in time of idling or not is checked. When a judgment hereat is YES, a speed detection signal is inputted from a speed sensor 10, and at this time if a car speed is zero, it is so judged that the accelerator opening sensor 8 is out of order, so a warning light 8L is lighted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an accelerator opening sensor failure diagnosis method for diagnosing whether or not an accelerator opening sensor for detecting the degree of depression of an accelerator pedal has failed.

[0002]

2. Description of the Related Art Generally, when the accelerator pedal is depressed, the amount of fuel to be supplied to the engine is increased. However, in a vehicle employing an electronically controlled fuel injection device, the amount of fuel injection depends on the engine rotation at that time. Based on the number and the degree of depression of the accelerator pedal, it is determined from an injection amount control map set in the controller. There are an idle switch and an accelerator opening sensor as sensors for detecting the depression state of the accelerator pedal.

The idle switch is a switch for detecting only whether or not the accelerator pedal is depressed, and is an ON switch when the accelerator pedal is not depressed and an OFF switch when the accelerator pedal is depressed. The accelerator opening sensor is a sensor for detecting the accelerator opening, which indicates how much the accelerator pedal is depressed.

FIG. 3 is a diagram showing the output characteristic of the accelerator opening sensor. The horizontal axis represents the accelerator opening, which is 100% when the accelerator pedal is fully depressed. The vertical axis represents the output from the accelerator opening sensor. The accelerator opening (%) can be known from this output. The center curve B is the reference output characteristic curve, curve A is the idle learning upper limit curve, and curve C is the idle learning lower limit curve.

The relationship between the accelerator opening and the accelerator opening sensor output should normally be the reference output characteristic curve (2), but there may be some deviation from that. That is, the output of the accelerator opening sensor when the idle switch is ON (when the accelerator opening is 0%) may deviate in a direction larger or smaller than the original value A.

However, if the deviation from A is within a certain range, the controller determines the value of the deviation as 0 degree of accelerator opening.
It learns that it is the accelerator opening sensor output at%, and interprets other outputs in consideration of the deviation. The idle learning upper limit curve a and the lower limit curve c indicate the upper limit and the lower limit of the range in which the accelerator opening can be normally detected by such learning. Therefore, for example, the allowable range of the accelerator opening sensor output when the accelerator opening is 0% is the range of B to C.

As described above, the output of the accelerator opening sensor is used to determine the injection amount of fuel in the electronically controlled fuel injection device, and whether the output is reliable or not is determined. It becomes a very important issue. Therefore, it is performed to diagnose whether or not the accelerator opening sensor is normal. For example, in the output characteristic diagram as shown in FIG. 3, when the value of the idle learning upper limit curve b when the accelerator opening is 100%, in other words, the maximum allowable output is M, the output from the accelerator opening sensor is larger than M. If there is, it is diagnosed that the accelerator opening sensor is out of order. This is because if it is larger than M, it is not possible to accurately detect what the accelerator opening degree is.

As a related conventional document, for example, there is JP-A-4-231652. This is to diagnose the failure of the idle switch in consideration of the output of the accelerator opening sensor. When the signal from the idle switch indicates the idle state, the output of the accelerator opening sensor is a value larger than the value of C in FIG. 3 shown in the present application (a value that should not be output if normal). If so, it is determined that the idle switch has failed.

[0009]

However, in the above-mentioned prior art, when the idle switch is ON (when the accelerator pedal is not depressed), the output of the accelerator opening sensor is M or less in FIG. Out of range (B to C
When the value is (out of), there is a problem that the failure cannot be detected.

Further, the technique disclosed in Japanese Patent Laid-Open No. 4-231652 has the following problems. That is, when the idle switch is ON and a value less than M but outside B to C is output, the accelerator opening sensor is normal, but the idle switch is faulty. The idle switch is normal, but the accelerator is open. The degree sensor may be either defective. However, in the technique disclosed in Japanese Patent Laid-Open No. 4-231652, the idle switch is erroneously diagnosed as a failure even in the case of. An object of the present invention is to solve the above problems.

[0011]

In order to solve the above problems, in the accelerator opening sensor failure diagnosis method of the present invention, an idle switch that is turned off when the accelerator pedal is depressed and turned on when the accelerator pedal is not depressed is on, The output changes according to the amount of pedal depression, and when the accelerator opening sensor outputs a value outside the allowable range for idle output and the output of the vehicle speed sensor indicates zero vehicle speed, the accelerator opening sensor malfunction is diagnosed. It was decided to.

[0012]

[Operation] By referring to the output from the vehicle speed sensor as the sensor output used for the accelerator opening sensor failure diagnosis, it is possible to more accurately diagnose the failure of the accelerator opening sensor. That is, when the idle switch is ON and the output of the accelerator opening sensor is a value outside the allowable range (outside of B to C) as the output during idling,
Conventionally, it has not been possible to determine whether the accelerator opening sensor has failed or the idle switch has failed. However, in the present invention, the output of the vehicle speed sensor is referred to, and if the vehicle speed is zero, the vehicle is in the idle state, so the idle switch that is ON can be determined to be normal, and the accelerator opening sensor has a failure. Can be judged.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 is a diagram showing an electronically controlled fuel injection device to which the method of the present invention is applied. In FIG. 2, 1 is an injection pump, 2 is an engine speed sensor, 3 is a fuel pipe, 4 is an electric governor, 5 is a timing control valve, 6 is a fuel pipe, 7 is a controller, and 7 is a controller.
-1 is a timer, 7-2 is an accelerator opening sensor abnormality flag, 7-3 is an idle switch abnormality flag, 8 is an accelerator opening sensor, 8L and 9L are warning lights, 9 is an idle switch, 10 is a vehicle speed sensor, 12 Is an intake pipe, 13 is an injection nozzle, 14 is a diesel engine, 15 is an exhaust gas recirculation pipe,
Reference numeral 16 is an exhaust pipe, and 17 is a turbocharger.

The accelerator opening sensor abnormality flag 7-2 is
It is a flag that is turned on (flag value “1”) when the accelerator opening sensor 8 is diagnosed as abnormal, and is turned off (flag value “0”) otherwise, and is set in the controller 7. The idle switch abnormality flag 7-3 is similarly set in the controller 7, and is turned on when the idle switch is diagnosed as abnormal, and is turned off otherwise.
Is a flag.

As will be described later, the timer 7-1 may have an abnormal value only transiently or instantaneously when the output value of the accelerator opening sensor is an abnormal value. It is provided for diagnosing after a time for the value to settle down without immediately diagnosing a failure. This may be provided outside the controller 7. The warning light 8L is lit when the accelerator opening sensor 8 is diagnosed as a failure, and the warning light 9L is lit when the idle switch 9 is diagnosed as a failure.

In this example, the diesel engine 14 is provided with the turbocharger 17, but, of course, the engine may not be provided. The intake air to the engine 14 is supercharged by the turbocharger 17. Fuel is supplied from the fuel pipe 3 to the injection pump 1, is sent to the injection nozzle 13 through the fuel pipe 6, and is injected into the diesel engine 14. The injection amount is controlled by the electric governor 4, and the injection timing is controlled by the timing control valve 5.

The control signals to the electric governor 4 and the timing control valve 5 are generated by the controller 7 based on the detection signals from various sensors and the like and the control map preset in the controller 7. The detection signal includes the engine speed detected by the engine speed sensor 2, the accelerator opening detected by the accelerator opening sensor 8, and the like. In the present invention, the detection signals from the accelerator opening sensor 8, the idle switch 9 and the vehicle speed sensor 10 are read into the controller 7 and processed by the procedure shown in the flow chart of FIG. 1 to determine whether the accelerator opening sensor is out of order. To diagnose.

FIG. 1 is a flow chart for explaining the accelerator opening sensor failure diagnosis method of the present invention. Hereinafter, description will be made step by step. Step 1 ... Read the output of the accelerator opening sensor 8. Step 2 ... That is the maximum allowable output of the accelerator opening (see FIG.
M) of the above. If it is larger than M, the accelerator opening sensor 8 may be diagnosed as a failure at this stage, so the routine proceeds to step 17 to turn on the accelerator opening sensor abnormality flag 7-2.

Step 3 ... If it is smaller than M, it is checked whether the signal from the idle switch 9 is ON. Step 4 ... If the signal from the idle switch 9 is OFF, it means that the accelerator pedal is being depressed, so the idle switch 9 is judged to be normal. Therefore, the idle switch abnormality flag 7-
3 is OFF (no abnormality). Step 5 ... If the signal from the idle switch 9 is ON (signal indicating that the accelerator pedal is not depressed ... Signal during idling), the output of the accelerator opening sensor 8 is allowed as a value to be taken during idling. Range (B in FIG. 3)
Check whether the value is outside of C).

Step 6 ... If the value is within the above range, the accelerator opening sensor 8 is judged to be normal because it is a normal value, and the accelerator opening sensor abnormality flag 7-2 is turned off.
(No abnormality) Step 7 ... If the output of the accelerator opening sensor 8 is outside the allowable range (outside of B to C), a vehicle speed detection signal is input from the vehicle speed sensor 10. Step 8: Check whether the vehicle speed detection signal indicates a vehicle speed of 0 or not. In the present invention, the detection signal from the vehicle speed sensor 10 is changed to the signal (ON, OFF) from the idle switch 9.
Is used for confirmation of trustworthiness.

Step 9: If the vehicle speed is not 0, it means that the vehicle is running. At this time, it is checked whether the timer 7-1 is operating. This flow chart is periodically flown with an extremely short time period, so the timer may have started counting at the time of the previous flow. Step 10 ... If not in operation, start timing.

Step 11: It is checked whether or not the time measured by the timer 7-1 has exceeded a predetermined time T seconds. If not, go back to step 1. This is because the output of the accelerator opening sensor 8 becomes an abnormal value or the vehicle speed detection signal is 0 when the vehicle speed is 0 only transiently or instantaneously for some reason.
May be indicated, but it is a measure to prevent diagnosis at such a value. Wait for the output to settle before making a decision about the output value.

Step 12 ... This step is reached at a value outside the range (B to C in FIG. 3) permitted as the value taken by the accelerator opening sensor output during idling, and the vehicle speed is reached. This is a case where the idle switch 9 is ON (= a signal value indicating that the accelerator pedal is not depressed) even though it is not 0 (that is, while traveling). In this case, it is determined that the idle switch 9 is out of order, and the idle switch abnormality flag 7-3 is turned on (abnormal). Step 13 ... The warning light 9L for notifying the abnormality of the idle switch 9 is turned on.

Step 14 ... If the vehicle speed is 0, it means that the vehicle is stopped, but at this time as well, for the same reason as in Step 9, it is checked whether the timer 7-1 is operating. Step 15 ... If not in operation, start timing. Step 16 ... Checks whether the time measured by the timer 7-1 has passed a predetermined time T seconds. If not, go back to step 1. This is for avoiding the judgment based on the transient and instantaneous values as in step 11.

Step 17 ... If the vehicle speed is 0 in Step 11, it means that the vehicle is stopped. In this case, the accelerator opening sensor abnormality flag 7-2 is turned on (abnormal).
And This is because the accelerator opening sensor 8 outputs a value outside the normal range even though it is stopped. Step 18 ... The warning lamp 8L for notifying the abnormality of the accelerator opening sensor 8 is turned on.

[0026]

As described above, according to the accelerator position sensor failure diagnosis method of the present invention, the output of the vehicle speed sensor is also referred to so that the idle switch is ON and the output of the accelerator position sensor is idle. Even if the output value is outside the allowable range (outside B to C), it is possible to accurately diagnose whether the idle switch or the accelerator opening sensor is out of order. I can do it.

[Brief description of drawings]

1 is a flow chart illustrating the method of the present invention.

FIG. 2 is a diagram showing an electronically controlled fuel injection device to which the method of the present invention is applied.

FIG. 3 is a diagram showing output characteristics of an accelerator opening sensor.

[Explanation of symbols]

1 ... Injection pump, 2 ... Engine speed sensor, 3 ... Fuel pipe, 4 ... Electric governor, 5 ... Timing control valve, 6 ... Fuel pipe, 7 ... Controller, 7-1 ... Timer, 7-2 ... Accelerator opening degree Sensor abnormality flag, 7-3 ... Idle switch abnormality flag, 8 ... Accelerator opening sensor, 8L, 9L ... Warning light, 9 ... Idle switch, 10 ... Vehicle speed sensor, 12 ... Intake pipe, 13 ... Injection nozzle, 14 ... Diesel Engine, 15 ... Exhaust gas recirculation pipe, 16 ... Exhaust pipe, 17 ... Turbocharger

Claims (1)

[Claims] 1. O when the accelerator pedal is depressed
When the idle switch is turned on when FF is not depressed, the output changes according to the accelerator pedal depression amount. The accelerator opening sensor outputs a value outside the allowable range for the idle output, and the output of the vehicle speed sensor. A method for diagnosing an accelerator opening sensor failure, wherein the accelerator opening sensor failure is diagnosed when the vehicle speed is zero.