JPH109036A - Device for diagnosing abnormality of sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct easily the standard point of a sensor, and improve the reliability of the diagnosis of abnormality of plural sensors detecting the same detecting object. SOLUTION: An accelerator sensor 27 is a two track type sensor which consists of a first and a second accelerator sensor 1 and 2. The first accelerator sensor 1 is connected between the power source Vc terminal of an ECU 25, and a grand GND terminal, the power source side of the second accelerator sensor 2 is connected to the power source Vc terminal of the ECU 25, through a resistance element 53 for offset, while the grand side of the second accelerator sensor 2 is connected to the grand GND terminal of the ECU 25 through a resistance element 54 for offset. Consequently, the offsets are provided to both the minimum value side and the maximum side of the output property of the second accelerator sensor 2, and by regulating the offset amounts (the resistance values of the resistance elements 53 and 54), the output value of the second accelerator sensor 2 in the fully closed condition can be set for a standard point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor abnormality diagnosis apparatus for diagnosing abnormality of a sensor based on outputs of a plurality of sensors for detecting the same object to be detected.

[0002]

2. Description of the Related Art For example, when a throttle opening of an internal combustion engine is detected by a sensor, two sensors (potentiometers) are provided as shown in Japanese Patent Application Laid-Open No. 63-71552, and the slope of the output characteristic of the sensor is determined. Along with making it different
In some cases, the rate of change in the output of two sensors is compared with a predetermined abnormality determination threshold value to diagnose a sensor abnormality. Also, in the sensor abnormality determination method disclosed in Japanese Patent Application Laid-Open No. 60-4838, the same detection target (intake pressure) is detected by using two sensors set to output characteristics having different inclinations, and the output of each sensor is detected. Each of them is compared with a predetermined value to diagnose a sensor abnormality.

In addition, in Japanese Patent Application Laid-Open No. 4-214949, the output characteristics of two sensors that detect the same detection target are set to mutually opposite characteristics (that is, the characteristics in which the increase and decrease of the output changes of the two sensors are reversed). Then, compare the output of each sensor with the permissible value to check the abnormality of each sensor,
Further, the difference between the outputs of the two sensors is compared with a predetermined abnormality determination threshold value to check for an abnormality in the entire sensor system.

[0004]

However, in the above, when two sensors are connected to a common ground for the purpose of simplifying the sensor circuit, even if floating (resistance is applied) occurs on the ground. Since the outputs of the two sensors change in the same manner, it is difficult to detect an abnormality. Moreover, the reference point correction of the sensor (for example, in the case of the throttle opening sensor, the correction of setting the output voltage when the throttle is fully closed to the reference voltage) is performed only for one of the sensors, and the reference point correction is performed for the other sensor. It was difficult to do. For this reason, the other sensor is used while including the error of the reference point, which causes a reduction in detection accuracy.

On the other hand, in the above, since the output characteristics of the two sensors are set to be opposite to each other, if the ground floats, the difference between the outputs of the two sensors changes, and it is possible to detect an abnormality. It is possible. However, even in this case, similarly to the above, only one of the sensors can correct the reference point, and the other sensor has to be used while including the error of the reference point.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and accordingly has as its object to detect a ground potential abnormality and to provide a reference point for a plurality of sensors for detecting the same object to be detected. An object of the present invention is to provide a sensor abnormality diagnosis apparatus that can perform all corrections and improve detection accuracy.

[0007]

In order to achieve the above object, a sensor abnormality diagnosis apparatus according to claim 1 of the present invention connects a plurality of sensors for detecting the same detection target to a common ground, An offset is provided on the minimum value side of the output characteristic of at least one sensor and on the maximum value side of the output characteristic of at least one sensor. This makes it possible to detect an abnormality in the ground potential by making the slopes of the output characteristics of the plurality of sensors different. Further, by adjusting the offset provided on the minimum value side and the maximum value side of the output characteristic of the sensor, the reference point of the sensor can be corrected, and the error of the reference point can be eliminated, thereby improving the detection accuracy. Can be.

In this case, for example, an offset may be provided on the minimum value side of the output characteristic of one sensor and an offset may be provided on the maximum value side of the output characteristic of the other sensor. It is preferable to provide offsets on both the minimum value side and the maximum value side of the output characteristics of the sensor. In this way, by adjusting the offsets on both the minimum value side and the maximum value side of the output characteristic of the same sensor, it is possible to adjust without changing the slope of the output characteristic of the sensor. Accordingly, it is possible to avoid a deviation of the sensor detection value due to a change in the inclination of the output characteristic of the sensor, and it is possible to maintain a good detection accuracy.

Further, in order to provide the offset, a resistive element is connected between at least one sensor and a ground, and a resistive element is connected between at least one sensor and a power supply. What should I do? With this configuration, an offset can be provided very easily using a very inexpensive resistance element, and the adjustment of the offset amount is extremely easy by replacing the resistance element with a resistance element having a different resistance value.

Also in this case, by connecting a resistance element to both the ground side and the power supply side of the same sensor, the offset can be offset to both the minimum value side and the maximum value side of the output characteristic of the same sensor. Is preferably provided. This allows
As in the third aspect, the adjustment can be performed without changing the inclination of the output characteristic of the sensor.

On the other hand, the output characteristics of the plurality of sensors are set so as to be opposite to each other.
An offset may be provided on at least one of the minimum value side and the maximum value side of the output characteristic of at least one sensor. In this case, by setting the output characteristics of the plurality of sensors to be opposite to each other, if the floating of the ground potential occurs, the abnormality can be detected. Therefore, the offset may be provided on at least one of the minimum value side and the maximum value side of the output characteristic of at least one sensor, and by adjusting this offset, the reference point of the sensor can be corrected.

In this case as well, in order to provide the offset, the offset may be connected to at least one of the ground side and the power supply side of at least one sensor.
With this configuration, the offset can be provided very easily using a very inexpensive resistance element.

[0013] The sensor abnormality diagnosis apparatus of the present invention includes:
The present invention is applicable to various systems that require fail-safe and reliability of a system using a sensor.
As described above, if the present invention is applied to a throttle control system having an accelerator opening sensor for detecting an accelerator opening or a throttle opening sensor for detecting a throttle opening, the reliability of the throttle control system can be improved.

It is preferable that an abnormality determination threshold value used for abnormality diagnosis of the sensor is set according to a minimum value of outputs of the plurality of sensors. By doing so, the accuracy of abnormality diagnosis can be improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment (1) of the present invention will be described below with reference to FIGS. First, a schematic configuration of the entire control system of the internal combustion engine 11 will be described with reference to FIG. An air cleaner 13 is mounted on an upstream side of an intake pipe 12 of the internal combustion engine 11, an air flow meter 14 for measuring an intake air amount Ga is provided on a downstream side thereof, and a throttle valve 15 is further provided on a downstream side thereof. A DC motor 17 is connected to the rotation shaft of the throttle valve 15,
The throttle valve 15 is driven by the driving force of the DC motor 17.
(Throttle opening) is controlled, and the throttle opening is detected by the throttle sensor 18.

An intake manifold 1 for introducing the intake air passing through the throttle valve 15 to each cylinder of the internal combustion engine 11
An injector 20 is attached to the cylinder 9, and a spark plug 21 is attached to a cylinder head of each cylinder of the internal combustion engine 11.
Is attached. Crankshaft 22 of internal combustion engine 11
A crank angle sensor 24 is mounted so as to face the outer periphery of the signal rotor 23 fitted to the engine. A pulse-shaped engine speed signal Ne output from the crank angle sensor 24 is supplied to an electronic control unit (hereinafter abbreviated as “ECU”). The engine speed is detected by the pulse interval of the engine speed signal Ne.

On the other hand, the depression amount of the accelerator pedal 26 (accelerator opening Ap) is detected by a two-track type accelerator sensor 27 described later, and a voltage signal corresponding to the accelerator opening Ap is sent to the A / D converter 28 by the ECU 25. Ingested through. Each voltage signal of the intake air amount Ga detected by the air flow meter 14 and the throttle opening TA detected by the throttle sensor 18 is also taken into the ECU 25 via the A / D converter 28.

The ECU 25 includes a CPU 29, a ROM 3
The microcomputer 29 mainly includes a microcomputer including a RAM 31 and the like. The CPU 29 executes various programs for controlling the internal combustion engine stored in the ROM 30 to control the ignition timing of the ignition plug 21 and to control the injector drive circuit. The fuel injection amount is controlled by controlling an injection pulse applied to the injector 20 through the fuel injection valve 45. Furthermore,
The ECU 25 includes a DC motor relay drive circuit 46 and a D / A conversion circuit 47. The D / A conversion circuit 47 is a circuit for performing D / A conversion of the throttle opening command value TTP calculated by the CPU 29 and outputting the converted value to the DC motor drive circuit 48.

Further, the DC motor drive circuit 48 includes a PID
It comprises a control circuit 49, a PWM (pulse width modulation) circuit 50 and a driver 51. Here, the PID control circuit 49 performs proportional control to reduce the deviation between the throttle opening command value TTP converted by the D / A conversion circuit 47 and the throttle opening TA detected by the throttle sensor 18. This is a circuit that executes processes (P), integration (I), and differentiation (D) to calculate the drive amount (control amount) of the DC motor 17. The drive amount signal output from the PID control circuit 49 is converted into a duty signal by the PWM circuit 50 and applied to the DC motor 17 via the driver 51.

On the other hand, the DC motor relay drive circuit 46
The DC motor relay 52 is turned ON / OF based on an ON (ON) / OFF (OFF) command output from the CPU 29.
F. When the DC motor relay 52 is turned on, the throttle valve 15 can be controlled by the DC motor 17 and the DC motor relay 52 is turned on.
Is turned off, the throttle valve 15 can be operated in a semi-mechanical manner corresponding to the accelerator operation, such as evacuation running.

Next, the configuration of the electronic throttle system will be described with reference to FIG. The accelerator pedal 26 is connected to an accelerator lever 34 via a wire 33. The accelerator lever 34 is urged downward (in the accelerator closing direction) by accelerator return springs 35 and 36. When the accelerator pedal 26 is not operated (accelerator OFF), the accelerator lever 34 is kept in contact with the accelerator fully closed stopper 37 by the accelerator return springs 35 and 36. During the operation of the engine, the position of the accelerator lever 34 is detected by the accelerator sensor 27 as the accelerator operation amount Ap.

On the other hand, a valve lever 38 is connected to a rotation shaft of the throttle valve 15, and the valve lever 38 is urged upward (in the opening direction of the throttle valve 15) by a retreating spring 39. When the DC motor relay 52 is turned off and the DC motor 17 is turned off, the retreat traveling spring 39 holds the valve lever 38 in contact with the intermediate lever 40. The intermediate lever 40 is urged downward by a valve return spring 41 (in a direction in which the throttle valve 15 is closed).

The tensile force of the valve return spring 41 is set to be larger than the tensile force of the retreat running spring 39. Therefore, the DC motor relay 52 is turned off.
In this state, the tensile force of the valve return spring 41 overcomes the tensile force of the evacuation travel spring 39, and the intermediate lever 40 is kept in contact with the intermediate stopper 42, thereby opening the throttle valve 15 Is regulated by the intermediate stopper 42 (approximately 3 deg)
Is held.

On the other hand, when the DC motor relay 52 is ON, the DC
By rotating the motor 17 forward or reverse, the throttle valve 15
Of the throttle valve 15 at that time (throttle opening) TA is detected by the throttle sensor 18. At this time, when opening the throttle opening TA, the DC motor 17 is rotated forward, and the valve lever 38 pushes up the intermediate lever 40 against the pulling force of the valve return spring 41 while the throttle valve 15
Drive in the direction to open the opening. Conversely, when closing the throttle opening TA, the DC motor 17 is rotated in the reverse direction to drive the throttle valve 15 in the closing direction while lowering the valve lever 38 so that the throttle valve 15 is closed.
When the valve lever 38 is closed to the fully closed stopper position (throttle opening = 0 deg), the valve lever 38 abuts on the throttle fully closed stopper 43, and further rotation is prevented.

Next, referring to FIG.
And the configuration of its peripheral circuits will be described. The accelerator sensor 27 is a two-track sensor composed of a first and a second accelerator sensor.
Is constituted by, for example, a contact potentiometer or a non-contact potentiometer using a Hall element (however, a contact potentiometer is shown in the circuit example of FIG. 3). The output of each accelerator sensor is EC
A through a low-pass filter 55 provided in U25
It is input to the / D converter 27 and read by the CPU 29.

Here, the first accelerator sensor is EC
The power supply Vc terminal of the ECU 25 is connected between the power supply Vc terminal of the U25 and the ground GND terminal.
+ 5V DC voltage is applied. On the other hand, the power supply Vc side of the second accelerator sensor is connected to the power supply Vc terminal of the ECU 25 through the offset resistance element 53, and the ground GND side of the second accelerator sensor is connected to the offset resistance element 54. Ground G of ECU 25
Connected to ND terminal. Therefore, the first and second accelerator sensors are connected to the power supply Vc terminal and the ground GND.
Both terminals are common.

In this case, by connecting the offset resistance element 53 to the power supply Vc side of the second accelerator sensor, as shown in FIG. The maximum value side of the output characteristic of the accelerator sensor is offset, and the resistance element 54 is connected to the ground GND side of the second accelerator sensor, thereby offsetting the minimum value side of the output characteristic of the second accelerator sensor. Each offset amount is determined by each resistance element 53,
As the resistance value of the resistor 54 increases, the resistance value increases. Therefore,
The correction of the reference point of the second accelerator sensor, which will be described later, may be performed by replacing each of the resistance elements 53 and 54 with one having a different resistance value.

The processing related to control of the accelerator sensor is performed by an accelerator sensor control routine shown in FIG.
The ECU 25 repeatedly executes the process every predetermined time or every predetermined crank angle. When the processing of this routine is started, first, in step 101, for example, RAM
A mirror check of an initial value of 31 and initialization of a flag and the like are executed.

Thereafter, in step 102, the first and second
A / D converter 27 outputs the output of the accelerator sensor
In step 103, the fully closed position of each accelerator sensor is learned. The learning of the fully closed position is based on the output value (minimum value) of each accelerator sensor when the accelerator pedal 26 is not depressed at all, that is, when the accelerator lever 34 is in contact with the accelerator fully closed stopper 37. ) Is read, the output value is learned as the fully closed position, and the learned value is used as the ECU.
25 in a backup RAM (not shown).

Then, in the next step 104, a process of calculating the accelerator opening from the output value (A / D converted value) of each accelerator sensor is performed. Specifically, the actual opening voltage value is obtained by subtracting the fully closed position learning value from the output value of each accelerator sensor, and using the accelerator sensor output voltage-accelerator opening conversion table of FIG. An accelerator opening is calculated for each actual opening voltage value.

Thereafter, at step 105, as shown in FIG. 7, the accelerator opening calculated from the output value of the first accelerator sensor is compared with the accelerator opening calculated from the output value of the second accelerator sensor. Then, the smaller one is finally selected as the accelerator opening. Thereafter, step 106
Then, a process of diagnosing the presence / absence of an abnormality of the accelerator sensor is executed.

This abnormality diagnosis process is executed as follows by an accelerator sensor abnormality diagnosis routine shown in FIG. First, in steps 201 and 202, it is determined whether learning of the fully closed position of the first and second accelerator sensors has been completed, and if the learning of the fully closed position has not been completed in any one of the processes, the subsequent processing is performed. This routine is terminated without performing. On the other hand, if the learning of the fully closed position of both the first and second accelerator sensors has been completed, step 203
Then, it is determined whether or not abnormality diagnosis is prohibited (for example, whether or not the battery voltage is low). Even if abnormality diagnosis is prohibited, this routine is terminated without performing the subsequent processing.

Therefore, only when the learning of the fully closed positions of the two accelerator sensors has been completed and the abnormality diagnosis is not prohibited, the process proceeds to step 204 and thereafter, and the abnormality diagnosis is executed as follows. First, in step 204, a deviation between the accelerator opening calculated from the output value of the first accelerator sensor and the accelerator opening calculated from the output value of the second accelerator sensor is calculated. In step 205, the value is compared with the abnormality determination threshold value. Here, the abnormality determination threshold is set by a function or a map using the accelerator opening as a parameter as shown in FIG. Further, as the accelerator opening for obtaining the abnormality determination threshold, the smaller one of the two accelerator openings calculated from the output values of both accelerator sensors is selected. This is because the accelerator opening finally selected in step 105 of FIG. 5 is smaller, and the abnormality diagnosis threshold is set accordingly, thereby improving the abnormality diagnosis accuracy.

The abnormality determination threshold value may be calculated using a function map using the engine torque as a parameter instead of a function map using the accelerator opening as a parameter. In this case, the engine torque can be calculated using a function map using the engine speed and the engine load as parameters.

If it is determined in step 205 that the opening deviation between the two accelerator sensors is equal to or greater than the abnormality determination threshold value, the flow advances to step 206 to determine whether this state has continued for a predetermined time. If the predetermined time has not elapsed, this routine is terminated without determining that the sensor is abnormal. Therefore, only when the state in which the opening deviation is equal to or larger than the abnormality determination threshold value continues for a predetermined time has elapsed, the process proceeds from step 206 to step 207, where it is finally determined that the sensor is abnormal. After executing the fail-safe operation such as running, at step 209, a warning lamp (not shown) is turned on to notify the driver of the sensor abnormality.

On the other hand, if it is determined in step 205 that the opening degree deviation is lower than the abnormality determination threshold value, the process proceeds to step 210, in which it is determined whether this state has continued for a predetermined time. If the predetermined time has elapsed, both accelerator sensors are determined to be normal (step 211),
If the predetermined time has not elapsed, the routine ends without determining that the sensor is normal at that stage.

In this routine, both accelerator sensors,
The opening degree deviation (difference in output value) is compared with the abnormality determination threshold value to diagnose the abnormality.
May be compared with a predetermined value to diagnose the abnormality.

Next, the effect of providing offsets on both the minimum value side and the maximum value side of the output characteristics of the accelerator sensor will be described.

FIG. 9 shows a conventional example (1) in which an offset is provided only on the minimum value side of the accelerator sensor. In this output characteristic, if a floating (resistance occurs) occurs on the common ground GND of the two accelerator sensors, the slope of the output characteristic of both accelerator sensors changes as shown by the dotted line in FIG. If the output change amounts V1 and V2 of both accelerator sensors at this time are converted into accelerator openings, both of them have the same accelerator opening A. Accordingly, the difference between the accelerator opening detected by the first accelerator sensor and the accelerator opening detected by the second accelerator sensor (this opening difference is compared with the abnormality determination threshold in step 205 in FIG. 6). Diagnosis of abnormalities) is ground GN
Even if a floating occurs in D, it does not change, and it is impossible to detect the floating of the ground GND as a sensor abnormality.

On the other hand, FIG. 10 shows a conventional example (2) in which an offset is provided only on the maximum value side of the accelerator sensor. In this output characteristic, when the common power supply voltage Vc of the two accelerator sensors rises, as shown by the dotted line in FIG. 10, the slope of the output characteristic of both accelerator sensors changes with the minimum output value as a base point. If the output change amounts V1 and V2 of both the accelerator sensors at this time are converted into the accelerator opening, both of them have the same accelerator opening B.
Therefore, the opening deviation between the two accelerator sensors does not change even if the power supply voltage Vc changes, and an abnormal change in the power supply voltage Vc cannot be detected as a sensor abnormality.

On the other hand, in the above-described embodiment (1), both the minimum value side and the maximum value side of the output characteristic of the accelerator sensor are offset, so that FIG.
As shown in (a), when the output change amounts V1 and V2 of the two accelerator sensors when floating occurs in the common ground GND of the two accelerator sensors are converted into accelerator openings, the two accelerator openings C are obtained. , D have different values. Therefore, the opening deviation between the two accelerator sensors changes when a floating occurs in the ground potential GND, whereby the floating of the ground potential GND can be detected as a sensor abnormality.

As shown in FIG. 11 (b), the output change amounts V1 and V2 of the two accelerator sensors when the common power supply voltage Vc increases.
Is converted into the accelerator opening, both accelerator openings C,
D has a different value. Therefore, the opening deviation between the two accelerator sensors changes when the power supply voltage Vc changes, whereby an abnormal change in the power supply voltage Vc can be detected as a sensor abnormality.

As described above, in the embodiment (1), both the minimum value side and the maximum value side of the output characteristic of the second accelerator sensor are offset. Accordingly, the output value of the first accelerator sensor when fully closed is set as a reference point in the fully closed position learning process, while the offset value of the output characteristic of the second accelerator sensor on the minimum value side and the maximum value side is offset. By adjusting the amount (the resistance value of the resistance elements 54 and 53),
The output value of the second accelerator sensor when fully closed can be set as the reference point. As a result, the error in the output value of the second accelerator sensor can be made significantly smaller than in the past, the guard of the fully closed position learning value can be made smaller, and a decrease in controllability due to erroneous learning can be minimized. .

Moreover, in the embodiment (1), the offsets (the resistance values of the resistance elements 54 and 53) provided on both the minimum value side and the maximum value side of the output characteristic of the second accelerator sensor.
Can be adjusted without changing the slope of the output characteristic of the accelerator sensor. As a result, it is possible to avoid a deviation of the sensor detection value due to a change in the inclination of the output characteristic of the accelerator sensor, and it is possible to maintain a good detection accuracy.

However, the present invention is not limited to this configuration.
As in the embodiment (2) shown in FIG. 12 and the embodiment (3) shown in FIG. 13, one offset (resistance element 53, 54) may be provided for each of the two accelerator sensors. In other words, the offset (resistance element 53) is shifted to the maximum value side (power supply Vc side) of the output characteristic of one accelerator sensor.
And an offset (resistance element 54) may be provided on the minimum value side (ground GND side) of the output characteristic of the other accelerator sensor. Alternatively, a total of four resistance elements may be provided on both the power supply Vc side and the ground GND side of both the accelerator sensors. In any of these cases, the intended object of the present invention can be achieved.

Further, according to the present invention, as in the embodiment (4) shown in FIGS. 14 and 15, for example, the connection between the power supply Vc side and the ground GND side of the second accelerator sensor is reversed.
The output characteristics of the first and second accelerator sensors may be opposite to each other (that is, the characteristics of output changes of the two accelerator sensors may be reversed).
In this case, the offset (the resistance elements 53 and 5) is set on both the minimum value side and the maximum value side of the output characteristic of the second accelerator sensor.
4) is provided.

In this configuration, when a floating occurs in the common ground GND of the two accelerator sensors, as shown by a dotted line in FIG.
Of the output characteristic changes. When the output change amounts V1 and V2 of both accelerator sensors at this time are converted into accelerator openings, the accelerator openings C and D (where C>
D) change in opposite directions. Therefore, the opening deviation between the two accelerator sensors changes when a floating occurs in the ground GND, whereby the floating of the ground GND can be detected as a sensor abnormality.

As shown in FIG. 15 (b), the output change amounts V1 and V2 of the two accelerator sensors when the common power supply voltage Vc of the two accelerator sensors rises.
Is converted into an accelerator opening, the accelerator openings C and D (where C> D) change in directions opposite to each other. Therefore, the opening deviation between the two accelerator sensors is determined by the power supply voltage V
When c changes, it changes, whereby an abnormal change in the power supply voltage Vc can be detected as a sensor abnormality.

When the output characteristics of the two accelerator sensors are set to be opposite to each other, the accelerator opening of the accelerator sensor changes in the opposite direction when the ground GND floats or the power supply voltage fluctuates as described above. Offset (resistance elements 53, 5)
Even without 4), when the ground GND floats or when the power supply voltage fluctuates, the opening deviation between the two accelerator sensors changes, and it can be detected as a sensor abnormality. However, if there is no offset in the output characteristics of the accelerator sensor, the output value of the accelerator sensor when fully closed cannot be corrected to the reference point.

In this respect, as in the above embodiment (4), the output characteristic of the accelerator sensor is offset (the resistance element 5
If (3, 54) is provided, the output value when the accelerator sensor is fully closed can be corrected to the reference point by adjusting the offset amount. Moreover, if this offset is provided on both the minimum value side and the maximum value side of the output characteristic of the accelerator sensor, the offset amount can be adjusted without changing the slope of the output characteristic of the accelerator sensor.

However, if the output characteristics of both accelerator sensors are opposite, only one offset may be used, and even in this case, the intended object of the present invention can be achieved. Further, when offsets are provided on both the minimum value side and the maximum value side of the output characteristic, one offset may be provided for each accelerator sensor, as in the examples of FIGS.

In each of the embodiments described above, the present invention is applied to abnormality diagnosis of an accelerator sensor. For example, the present invention is applied to abnormality diagnosis of a vehicle-mounted sensor such as a throttle sensor and an intake pipe pressure sensor. The present invention is not limited to sensors mounted on a vehicle, and may be applied to abnormality diagnosis of various sensors used in various systems requiring reliability.

In addition, the present invention can be implemented with various modifications without departing from the gist of the present invention, for example, the present invention can be applied to a system for detecting the same object to be detected by three or more sensors.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an entire system showing an embodiment (1) of the present invention.

FIG. 2 is a schematic configuration diagram of an electronic throttle system.

FIG. 3 is a circuit diagram showing a configuration of an accelerator sensor and a configuration of peripheral circuits thereof;

FIG. 4 is a diagram showing output characteristics of an accelerator sensor.

FIG. 5 is a flowchart showing a flow of processing of an accelerator sensor control routine.

FIG. 6 is a flowchart illustrating a flow of processing of an accelerator sensor abnormality diagnosis routine;

FIG. 7 is a diagram conceptually showing a procedure for calculating an accelerator opening from output values of two accelerator sensors.

FIG. 8 is a diagram showing a relationship between an abnormality determination threshold value and an accelerator opening.

FIG. 9 is a diagram showing a conventional sensor output characteristic (1).

FIG. 10 is a diagram showing a conventional sensor output characteristic (2).

FIG. 11 shows a sensor output characteristic of the embodiment (1),
(A) is a diagram for explaining a change in characteristics when GND floats, (b)
Is a diagram explaining the characteristic change when the power supply voltage rises

FIG. 12 is a circuit diagram showing a connection example of an offset resistance element according to the embodiment (2).

FIG. 13 is a circuit diagram showing a connection example of an offset resistance element in the embodiment (3).

FIG. 14 is a circuit diagram showing a connection example between two accelerator sensors and an offset resistance element in the embodiment (4).

FIG. 15 shows a sensor output characteristic of the embodiment (4),
(A) is a diagram for explaining a change in characteristics when GND floats, (b)
Is a diagram explaining the characteristic change when the power supply voltage rises

[Explanation of symbols]

11 internal combustion engine, 12 intake pipe, 15 throttle valve, 17 DC motor, 18 throttle sensor, 25
... Electronic control unit (ECU), 26 ... Accelerator pedal, 27 ... Accelerator sensor, 34 ... Accelerator lever, 3
5, 36 ... accelerator return spring, 37 ... accelerator fully closed lever, 38 ... valve lever, 39 ... retreat running spring, 40 ... intermediate lever, 41 ... valve return spring, 42 ... intermediate stopper, 43 ... throttle fully closed stopper, 53, 54 ... resistance element, ... accelerator sensor (sensor).

Claims (8)

[Claims] 1. An abnormality diagnosis apparatus for a sensor applied to a system for detecting the same detection target by a plurality of sensors and diagnosing an abnormality of the sensors based on outputs of the plurality of sensors, wherein the plurality of sensors are shared. Connected to the ground of
An abnormality diagnosis device for a sensor, wherein an offset is provided on a minimum value side of an output characteristic of at least one sensor and a maximum value side of an output characteristic of at least one sensor. 2. The sensor abnormality diagnostic device according to claim 1, wherein offsets are provided on both the minimum value side and the maximum value side of the output characteristic of the same sensor. 3. The offset is provided by connecting a resistive element between at least one sensor and the ground, and connecting a resistive element between at least one sensor and a power supply. The sensor abnormality diagnostic device according to claim 1, wherein: 4. The sensor abnormality diagnostic device according to claim 2, wherein the offset is provided by connecting a resistance element to both the ground side and the power supply side of the same sensor. 5. A sensor abnormality diagnosis apparatus applied to a system for detecting the same detection target with a plurality of sensors, and diagnosing an abnormality of the sensors based on outputs of the plurality of sensors. An abnormality diagnosis device for a sensor, wherein the characteristics are set to be opposite to each other, and an offset is provided on at least one of the minimum value side and the maximum value side of the output characteristic of at least one sensor. 6. The sensor abnormality diagnosis according to claim 5, wherein the offset is provided by connecting a resistance element to at least one of a ground side and a power supply side of at least one sensor. apparatus. 7. The sensor according to claim 1, wherein the plurality of sensors are an accelerator opening sensor that detects an accelerator opening or a throttle opening sensor that detects a throttle opening. Abnormal diagnostic device for sensors. 8. The system according to claim 1, wherein an abnormality determination threshold value used for abnormality diagnosis of said sensor is set according to a minimum value of outputs of said plurality of sensors. An abnormality diagnosis device for the sensor described in the above.