JP2003201907A - Device and method for diagnosing sensor failure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To diagnose output shortages between sensors as well as sensor failure due to power output fluctuations and ground potential fluctuations. <P>SOLUTION: The sensor failure is detected based on sensor outputs from a first TPS61 and a second TPS62. A sensor's abnormality diagnostic part 13 controls a switching part 12, and output characteristics of the first TPS61 and the second TPS62 are set at a first output characteristics mode of which the inclinations vary respectively to diagnose the sensor abnormality due to the power output fluctuations and the ground potential fluctuations based on a gap of measurement values obtained from the respective sensor outputs in this mode. The output characteristics of the first TPS61 and the second TPS62 are set at a second output characteristic mode in which the output values at the respective identical measurement points do not conform to in a measurement range to diagnose the sensor failure due to the output shortage based on the gap of the respective sensor outputs in this mode. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for detecting a sensor abnormality by using output values from a plurality of sensors which measure the same object.

[0002]

2. Description of the Related Art As a technique for detecting an abnormality in a sensor by using output values from a plurality of sensors which measure the same object, there is a sensor abnormality diagnosing device described in Japanese Patent Laid-Open No. 10-9036. In this technique, two throttle position sensors (hereinafter, TPS) for detecting the throttle opening are provided, and one of them is provided with an offset resistance for offsetting the maximum value side of the output characteristic in the negative direction and a minimum value side of the output characteristic. An offset resistor for offsetting in the positive direction is provided. As a result, as shown in FIG. 3, the output characteristics (throttle opening-output voltage characteristics) of each of the two TPSs are set so that their inclinations are different from each other (in this figure, the 2T
Offset resistance is provided on PS). In addition, TPS
In terms of an equivalent circuit, an output terminal is provided on a resistor whose one end is grounded and the other end is connected to a power source, and the output value from this output terminal is a variable that changes according to the change in throttle opening. Expressed as resistance.

By setting the output characteristics of each of the two TPSs so that their slopes are different from each other, the two TPSs are
When the output values of the two TPS change in the same direction by the same value ΔV due to the change of the output value of the power supply that supplies power to the PS or the change of the ground potential of the two TPS. As shown in FIG. 3, the influence is expressed as a difference (deviation) Δσ of the throttle opening which is a measured value. Therefore, by obtaining the difference Δσ between the throttle opening degrees obtained from the output values of the two TPS, it is possible to detect the sensor abnormality due to the output value variation of the power supply and the ground potential variation.

[0004]

By the way, the above-mentioned conventional technique is intended to detect a sensor abnormality due to an output value variation of a power supply or a ground potential variation, and to detect an output short circuit between a plurality of sensors. No consideration whatsoever.

In the above conventional technique, when the same type (product) is used as a plurality of sensors and the output characteristics of the plurality of sensors are set to have different inclinations by using an offset resistance, as shown in FIG. In addition, a point C where the output characteristics of the plurality of sensors intersect is generated. When this intersection point C is present, when the output values of the plurality of sensors are the same, it is determined whether it is due to the intersection point C or due to an output short circuit between the plurality of sensors. I can't.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sensor abnormality diagnosing device for detecting a sensor abnormality by using output values from a plurality of sensors which measure the same object. In addition to diagnosing a sensor abnormality due to output value fluctuations of a power supply that supplies power to the plurality of sensors and ground potential fluctuations of the plurality of sensors, an output short circuit between the plurality of sensors can be diagnosed. is there.

[0007]

In order to solve the above-mentioned problems, the sensor abnormality diagnosing device of the present invention uses the first output having different inclinations for the output characteristics of a plurality of sensors which measure the same object. It has a switching means for switching to either the characteristic mode or the second output characteristic mode in which the output values at the same measurement points do not match in the measurement range.
Further, in the first output characteristic mode, a first abnormality for detecting a sensor abnormality is determined by determining whether a difference between measured values obtained from the output values of the plurality of sensors is within a predetermined value. Second abnormality detection processing for detecting a sensor abnormality by determining whether a difference between output values of the plurality of sensors is equal to or more than a predetermined value in the detection processing mode and the second output characteristic mode And modes.

According to the present invention, the first abnormality detection processing mode causes fluctuations in the output value of the power supply for supplying power to the plurality of sensors or fluctuations in the ground potential of the plurality of sensors, as in the prior art. A sensor abnormality can be diagnosed. A second abnormality detection processing mode for checking the output values of the plurality of sensors in the second output characteristic mode in which the output values of the plurality of sensors do not match at the same measurement point in the measurement range. This makes it possible to diagnose an output short circuit between the plurality of sensors.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below, taking as an example the case where the sensor abnormality diagnosis device of the present invention is applied to an internal combustion engine control system. FIG. 1 is a schematic connection diagram of an internal combustion engine control system to which an embodiment of the present invention is applied.

In this internal combustion engine control system, the torque request from the accelerator pedal 21 is converted into an electric signal by the accelerator position sensor 20 (hereinafter referred to as APS), and this is input to the internal combustion engine control device 10. The internal combustion engine control device 10 specifies the accelerator position from the electric signal from the APS 20, and based on this, calculates and obtains the target throttle opening degree for supplying the optimum air amount to the internal combustion engine.

Further, the opening of the throttle valve 50 is set to TPS6.
It is converted into an electric signal by 0, and this is input to the internal combustion engine control device 10. The internal combustion engine control device 10 uses the TPS60.
The actual throttle opening degree is specified from the electric signal from, and a current is supplied to the throttle motor 40 so that the actual throttle opening degree becomes the target throttle opening degree, and the opening degree of the throttle valve 50 is controlled.

Further, in this internal combustion engine control system,
The information of the air flow sensor 30 for measuring the intake air amount and the information of the crank angle sensor 90 are used as the internal combustion engine control device 10.
To enter. The internal combustion engine control device 10 calculates and obtains the optimum ignition timing and the mixture ratio of fuel and air based on these input information. Then, the ignition device 80 and the fuel injection device 70 are controlled based on the calculation result.

In the internal combustion engine control system of the present embodiment having the above-mentioned structure, two systems of APS 20 and TPS 60 are provided. Then, the internal combustion engine control device 10 is provided with a sensor abnormality diagnosis function of these two sensors provided in two systems. Figure 2 shows TP with two systems
S60 and TPS6 provided in the internal combustion engine controller 10
It is a figure for demonstrating the sensor abnormality diagnostic part of 0, and its peripheral circuit.

As described above, the TPS 60 is the first TP.
It is composed of two systems, S61 and second TPS62. As shown, the first TPS 61 and the second TPS 62
Is equivalent to an output terminal (Vo) on a resistor whose one end is grounded and the other end is connected to a power supply (reference voltage 26).
ut) is provided, and the resistance value (output voltage) at the output terminal is represented by a variable resistance that changes according to a change in the throttle opening.

Further, the internal combustion engine controller 10 has a first T
Reference voltage 11 for supplying power to PS 61 and second TPS 62, switching unit 12, and sensor abnormality diagnosis unit 13
And.

In accordance with an instruction from the sensor abnormality diagnosing unit 13, the switching unit 12 sets the output characteristics (output voltage-throttle opening characteristic) of the first TPS 61 and the second TPS 62 to the first output characteristic mode and the second output characteristic mode. Switch to one of. Here, the first output characteristic mode is as shown in FIG.
As shown in, the output characteristics of the first TPS 61 and the second TPS 62 are modes set so that the respective inclinations are different. On the other hand, the second output characteristic mode is, as shown in FIG. 4, that the output characteristics of the first TPS 61 and the second TPS 62 are such that the output values at the same measurement points do not match in the measurement range, that is, the intersection point C. It is a mode that is set not to occur.

As shown in FIG. 2, the switching unit 1 of this embodiment.
Reference numeral 2 denotes a first offset resistor 123 inserted between a ground side terminal of the second TPS 62 and the ground, a power source side terminal of the first TPS 61 and the reference voltage 11, and a second TPS.
Second offset resistors 121a and 121b respectively inserted between the power supply side terminal of 62 and the reference voltage 11;
Short circuit between both terminals of offset resistors 121a and 121b
And transistors 122a and 122b each functioning as a switch for controlling release. Then, the sensor abnormality diagnosis unit 13 turns on / off the transistors 122a and 122b, and the second offset resistors 121a and 121b.
By controlling the short circuit / release of b, it is possible to switch to either the first output characteristic mode or the second output characteristic mode.

Specifically, by turning on the transistor 122a and turning off the transistor 122b,
The first output characteristic mode shown in FIG. 3 is realized. In addition, the transistor 122a is turned off and the transistor 1
By turning on 22b, the second output characteristic mode shown in FIG. 4 is realized. In the present embodiment, the same product as the first TPS 61 and the second TPS 62,
That is, it is premised that those having the same output characteristics are used under the same conditions. Then, it is premised that the first offset resistor 123 and the second offset resistor 121a have the same resistance value.

In the above-mentioned structure, the sensor abnormality diagnosis section 13 controls the switching section 12 to set the first output characteristic mode. Then, based on the first output characteristic mode, the throttle opening is obtained from the output voltage of each of the first TPS 61 and the second TPS 62, and it is diagnosed whether the difference (deviation) is less than or equal to a predetermined value. If it is not equal to or less than the predetermined value, it is detected that a sensor abnormality has occurred due to a variation in the output value of the power supply or a variation in the ground potential (first abnormality detection processing mode).

The sensor abnormality diagnosing section 13 includes a switching section 1
2 is set to the second output characteristic mode. Then, it is diagnosed whether the difference between the output voltages of the first TPS 61 and the second TPS 62 is greater than or equal to a predetermined value. If it is not greater than or equal to the predetermined value, it is detected that a sensor abnormality has occurred due to an output short circuit between the first TPS 61 and the second TPS 62 (second abnormality detection processing mode).

FIGS. 5 and 6 are views for explaining the sensor abnormality diagnosis flow in the sensor abnormality diagnosis unit 13 shown in FIG. 2. FIG. 5 shows the first abnormality detection processing mode, and
FIG. 6 shows an operation flow in the second abnormality detection processing mode.

First, in the first abnormality detection processing mode, the sensor abnormality diagnosis section 13 controls the switching section 12 to
The first output characteristic mode shown in FIG. 3 is set (S40).
1). Then, the first TPS 61 and the second TPS 62
Of the sensor output (output voltage) of the first TPS 61 according to the output characteristics of the first TPS 61 in the first output characteristic mode at the same time.
The throttle opening (referred to as the first throttle opening) is calculated from the sensor output of the TPS 61, and the second TPS 62 is operated according to the output characteristics of the second TPS 62 in the first output characteristics mode.
The throttle opening (referred to as the second throttle opening) is obtained from the sensor output of 62 (S402).

Next, the sensor abnormality diagnosing unit 13 obtains a difference (deviation) between the first throttle opening and the second throttle opening (S403), which is less than or equal to a predetermined first abnormality determination threshold value. Is checked (S404).

Here, the first abnormality determination threshold is the first
Considering the accuracy of the TPS61 and the second TPS62, the first
It is preferable to set the difference between the throttle opening and the second throttle opening to a value not less than the value that is not recognized as a variation due to an error.

In step S404, when the difference between the first throttle opening and the second throttle opening is less than or equal to the first abnormality determination threshold value, the sensor abnormality diagnosing unit 13 causes the output value fluctuation of the power source and the ground contact. It is determined that the sensor abnormality due to the potential fluctuation has not occurred, and the second abnormality detection processing mode (S
408).

On the other hand, in S404, if the difference between the first throttle opening and the second throttle opening is not less than or equal to the first abnormality determination threshold value, the sensor abnormality diagnosis unit 13 is erroneously determined due to the influence of noise or the like. In order to prevent this, it is determined whether or not the state where the difference between the first throttle opening and the second throttle opening is not less than or equal to the first abnormality determination threshold value continues for a predetermined time or more (S405).

For example, when the determination in S404 that the difference between the first throttle opening and the second throttle opening is not less than or equal to the first abnormality determination threshold value is repeated N times in succession, It is determined that it has continued for a predetermined time or longer.

If the state in which the difference between the first throttle opening and the second throttle opening is not less than or equal to the first abnormality determination threshold value does not continue for a predetermined time or longer, the second abnormality detection processing mode is set. If the process proceeds to (S408) and continues for a predetermined time or more, it is determined that the sensor abnormality due to the output value variation of the power supply or the ground potential variation has not occurred (S4).
06), necessary processing such as shift to fail-sale mode is executed (S407), and then shifts to the second abnormality detection processing mode (S408).

Next, in the second abnormality detection processing mode, if the sensor abnormality diagnosis section 13 has not shifted to the fail-sale mode (S4081), the sensor abnormality diagnosis section 13 controls the switching section 12 to display the second abnormality shown in FIG. To the output characteristic mode (S4082). Then, the first TPS 61 and the second
The sensor output of the TPS 62 (the sensor output of the first TPS 61 is the first sensor voltage and the sensor output of the second TPS 62 is the second sensor voltage.
At the same time, the sensor voltage is called (S4083).

Next, the sensor abnormality diagnosis section 13 obtains a difference (deviation) between the first sensor voltage and the second sensor voltage (S4).
084), and it is checked whether this is greater than or equal to a predetermined second abnormality determination threshold value (S4085).

Here, the second abnormality determination threshold value is larger than a voltage error caused by, for example, a variation in accuracy of the first TPS 61 and the second TPS 62, and the first offset resistance in the second output characteristic mode. It may be set to a value equal to or lower than the voltage value applied to 123.

If the difference between the first sensor voltage and the second sensor voltage is greater than or equal to the second abnormality determination threshold value in S4085, the sensor abnormality diagnosis section 13 determines that the first TPS has occurred.
It is determined that the sensor abnormality due to the output short circuit between 61 and the second TPS 62 has not occurred, and the process shifts to the first abnormality detection processing mode (S401).

On the other hand, in S4085, when the difference between the first sensor voltage and the second sensor voltage is not greater than or equal to the second abnormality determination threshold value, the sensor abnormality diagnosis unit 13 is erroneously determined due to the influence of noise or the like. In order to prevent the above, it is determined whether or not the state where the difference between the first sensor voltage and the second sensor voltage is not greater than or equal to the second abnormality determination threshold value continues for a predetermined time or more (S4086).

For example, if the determination in S4085 that the difference between the first sensor voltage and the second sensor voltage is not greater than or equal to the second abnormality determination threshold value is repeated N times in succession, a predetermined time It is determined that the above continues.

When the difference between the first sensor voltage and the second sensor voltage is not greater than or equal to the second abnormality determination threshold value,
If it has not continued for a predetermined period of time or longer, it returns to the first abnormality detection processing mode (S401), and if it has continued for a predetermined period of time or more, it is judged that no sensor abnormality has occurred due to an output short circuit (S4087). , Execute necessary processing such as transition to fail-sale mode (S408
8) and then returns to the first abnormality detection processing mode (S
401).

The embodiment of the present invention has been described above.

According to the present embodiment, the output value fluctuation of the reference voltage 11 for supplying electric power to the first TPS 61 and the second TPS 62 and the first TPS in the first abnormality detection processing mode.
It is possible to detect the sensor abnormality due to the ground potential fluctuation of 61 and the second TPS 62. Further, in the second output characteristic mode in which the sensor voltages of the first TPS 61 and the second TPS 62 at the same measurement point do not match in the measurement range, the second abnormality detection processing mode for checking the sensor voltage value of the first TPS 61 and the second TPS 62 causes First TPS61
It is also possible to detect an output short circuit between the second TPSs 62.

Further, according to the present embodiment, by turning on / off the transistors 122a and 122b to control the short circuit / open of the second offset resistors 121a and 121b, the structure is relatively simple and inexpensive, It is possible to switch between the first output characteristic mode and the second output characteristic mode. In addition, the second offset resistor 121
The first output characteristic mode and the second output characteristic mode are switched by controlling the short-circuiting / opening of a and 121b, and thereby the first TPS 61 and the second TPS 62.
There is an advantage that the same product can be used as.

In the above description, the configuration and operation for diagnosing the sensor abnormality of the TPS 60 (T provided in two systems).
PS60 and TPS provided in the internal combustion engine controller 10
Although the sensor abnormality diagnosing unit of 60 and its peripheral circuits have been described, the above description is for the configuration and operation for diagnosing the sensor abnormality of the APS 20 (AP having two systems).
S20 and APS2 provided in the internal combustion engine controller 10
0 sensor abnormality diagnosis unit and its peripheral circuit) can be provided in the same manner.

The present invention is not limited to the above embodiment, but various modifications can be made within the scope of the gist thereof.

For example, the first output characteristic mode and the second output characteristic mode
The configuration of the switching unit 12 for switching the output characteristic mode of is not limited to that shown in FIG. How to arrange the offset resistor and which offset resistor is to be short-circuited / opened are freely determined within the range in which the first output characteristic mode and the second output characteristic mode can be switched. You can

Further, for example, when the sensor abnormality diagnosis unit 13 has a high sensor voltage resolution and a wide input range, an output characteristic mode having the characteristics of both the first output characteristic mode and the second output characteristic mode, That is, by using the third output characteristic mode in which the inclinations of the output characteristics of the plurality of sensors are different and the output values of the plurality of sensors at the same measurement point do not match in the measurement range, the switching unit 12 can be omitted. In this case, in the third output characteristic mode, by executing the first abnormality detection processing mode and the second abnormality detection processing mode, respectively, a sensor abnormality due to a power supply voltage fluctuation or a ground potential fluctuation, and a plurality of sensors are detected. It is possible to detect both a sensor abnormality due to an output short circuit between them.

Further, the present invention is widely applied not only to sensor abnormality diagnosis in an internal combustion engine control system, but also to various sensor abnormality diagnosis for detecting sensor abnormality based on output values from a plurality of sensors which measure the same object. it can.

[0044]

As described above, according to the present invention,
In a sensor abnormality diagnosis device that detects a sensor abnormality using output values from a plurality of sensors that measure the same object, fluctuations in output values of a power supply that supplies power to the plurality of sensors and ground potential of the plurality of sensors. In addition to diagnosing a sensor abnormality due to fluctuation, it is possible to diagnose an output short circuit between the plurality of sensors.

[Brief description of drawings]

FIG. 1 is a schematic connection diagram of an internal combustion engine control system to which an embodiment of the present invention is applied.

FIG. 2 is a diagram showing an internal combustion engine control system shown in FIG.
FIG. 3 is a diagram for explaining a TPS 60 provided in a system, a sensor abnormality diagnosis unit of the TPS 60 provided in the internal combustion engine control device, and a peripheral circuit thereof.

FIG. 3 is a diagram for explaining a first output characteristic mode.

FIG. 4 is a diagram for explaining a second output characteristic mode.

FIG. 5 is a flowchart for explaining a first sensor abnormality detection processing mode.

FIG. 6 is a flowchart for explaining a second sensor abnormality detection processing mode.

[Explanation of symbols]

10 ... Internal combustion engine control device, 11 ... Reference voltage, 12 ... Switching part, 13 ... Sensor abnormality diagnosis part, 20 ... APS, 21 ... Accelerator pedal, 30 ... Airflow sensor, 40 ... Throttle motor, 50 ... Throttle valve, 60 ... TPS, 61
... 1st TPS, 62 ... 2nd TPS, 70 ... Fuel injection device, 80 ... Ignition device, 90 ... Crank angle sensor, 121
a, 121b ... Second offset resistance, 122a, 122
b ... transistor, 123 ... first offset resistor

Continued front page    F term (reference) 3G084 BA00 BA05 DA27 DA30 EA03                       EA04 EA09 EA11 EB22 EC03                       FA07 FA10 FA34                 3G301 HA01 JB01 LA03 NB02 NB04                       PA01Z PA11Z PE01Z

Claims (6)

[Claims] 1. A sensor abnormality diagnosing device for diagnosing a sensor abnormality based on output values from a plurality of sensors measuring the same object, the output characteristics of the plurality of sensors having different inclinations. A first output characteristic mode and a switching means for switching to one of the second output characteristic modes in which the output values at the same measurement points do not match in the measurement range, and an abnormality detection means, The abnormality detecting unit detects a sensor abnormality by determining whether or not a difference between measured values obtained from output values of the plurality of sensors is within a predetermined value in the first output characteristic mode. In the first abnormality detection processing mode and the second output characteristic mode,
A second method for detecting a sensor abnormality by determining whether a difference between output values of the plurality of sensors is equal to or more than a predetermined value.
And an abnormality detection processing mode. 2. The sensor abnormality diagnosis device according to claim 1, wherein the sensor has a resistor having one end grounded and the other end connected to a power source,
An output terminal is provided, and as the variable resistance whose output value from the output terminal changes according to the change of the measurement object,
Expressed as an equivalent circuit, the abnormality detection means, in the first abnormality detection processing mode, when the difference between the measured values obtained from the output values of the plurality of sensors is not within a predetermined value, the output value of the power supply. It is determined that there is a fluctuation or a fluctuation in the ground potential, and in the second abnormality detection processing mode, when the difference between the output values of the plurality of sensors is not equal to or more than a predetermined value, the outputs of the plurality of sensors are short-circuited. A sensor abnormality diagnosing device characterized by being judged as a thing. 3. The sensor abnormality diagnosing device according to claim 1, wherein the switching unit sets a minimum value side of output characteristics of the sensor, which is provided in at least one of the plurality of sensors. A first offset means for offsetting in the positive direction, and a second offset provided in at least one of the plurality of sensors for offsetting the maximum value side of the output characteristics of the sensor in the negative direction A sensor abnormality diagnosing device comprising: a means and a switch means for turning on / off the offset by the first offset means and / or the second offset means. 4. The sensor abnormality diagnosis device according to claim 3, wherein the offset means is a resistance element, and the switch means is a transistor connected so as to short-circuit / release both ends of the resistance element. A sensor abnormality diagnosing device characterized by being present. 5. The sensor abnormality diagnosing device according to claim 1, wherein the sensor outputs an output value according to a throttle opening degree or an accelerator opening degree of an automobile. Characteristic sensor abnormality diagnostic device. 6. A sensor abnormality diagnosing method for detecting abnormality of the sensor based on output values from a plurality of sensors which measure the same object. Are set to different first output characteristic modes, and in the first output characteristic mode, it is determined whether the difference between the measured values obtained from the output values of the plurality of sensors is within a predetermined value or not. ,
A first abnormality detection step of detecting a sensor abnormality, and setting the output characteristics of the plurality of sensors to a second output characteristic mode in which the output values at the same measurement points in the measurement range do not match, A second abnormality detection step of detecting a sensor abnormality by determining whether or not a difference between output values of the plurality of sensors is equal to or more than a predetermined value in the second output characteristic mode. A method for diagnosing a sensor abnormality.