JPH0782058B2 - Sensor system abnormality detection device - Google Patents

Description

The present invention relates to a sensor system for detecting an abnormality between a sensor such as a temperature sensor and a pressure sensor and a sensor signal transmission system such as a connector for transmitting the output of the sensor and a signal line. An abnormality detection device.

[Conventional technology]

Sensors that detect physical or chemical quantities as electrical signals are used in various systems. For example,
In an automobile internal combustion engine control system, a potentiometer is used for the air flow meter that measures the intake air amount, a temperature sensor is used for detecting the cooling water temperature, and the internal combustion engine controller uses the detection voltage of these sensors and other various sensors. Is taken in through a connector, a harness, etc., and optimal internal combustion engine control is executed based on the value.

In a system in which some control is performed based on the output of such a sensor, an abnormality in the sensor system including the connector etc. immediately causes an abnormality in the system. It is desirable to detect and take measures.

Therefore, conventionally, such a system is also provided with a sensor system abnormality detection device that detects whether or not an abnormality has occurred in the sensor system.

Conventionally, this type of sensor system abnormality detection device generally detects a sensor abnormality by comparing a sensor output voltage with a preset abnormality determination voltage. For example, in the case of the temperature sensor that detects the cooling water temperature, the upper limit of the cooling water temperature naturally has a limit, and therefore, for example, when the temperature sensor shows a value above the limit, it is assumed that an abnormality occurs in the temperature sensor. is there.

[Problems to be solved by the invention]

However, the above-described conventional device can effectively detect when a fixed failure occurs due to complete destruction of the element itself that constitutes the sensor, the connector, or the like, but there is rattling of the connector portion, poor assembly of the harness, and failure of the power supply. Due to momentary interruptions, poor contact inside the elements that make up the sensor, etc., frequent intermittent failures, that is, fixed failures, do not occur, but intermittent failures that have a large impact on control cannot be detected sufficiently. there were.

The present invention solves such a conventional drawback, and an object thereof is to provide a sensor system abnormality detection device capable of sufficiently detecting an intermittent failure that does not lead to a fixed failure but has a great influence on control. Especially.

[Means for solving problems]

In order to achieve the above object, the present invention provides a sensor system including a sensor 1 and a sensor signal transmission system 3 for inputting an output voltage of the sensor 1 to a processing device 2 as shown in FIG. In a sensor system abnormality detection device for detecting an abnormality, a sensor change voltage detection means 4 for detecting a change voltage ΔV of a sensor voltage SV guided to a processing device 2 by a sensor signal transmission system 3 per predetermined time, and a sensor change voltage The sensor change voltage allowance storage means 5 for storing the allowance value Vl, the comparing means 6 for comparing the sensor change voltage ΔV detected by the sensor change voltage detecting means 4 with the sensor change voltage allowance value Vl, and the comparing means 6. An abnormal number counting means 7 for counting the number of times the sensor change voltage ΔV exceeds the sensor change voltage allowable value Vl;
The abnormal number allowable value storage means 8 for storing the allowable number Nl of abnormal times and the sensor system when the abnormal number N counted by the abnormal number counting means 7 within a preset time exceeds the abnormal number allowable value Nl The determination means 9 for determining abnormality is provided.

[Action]

A change in the sensor voltage SV that cannot occur in normal operation due to loosening of the connector forming the sensor signal transmission system 3, harness, power interruption, contact failure inside the element forming the sensor 1, and the like. Indicates the sensor change voltage ΔV
Exceeds the sensor change voltage permissible value Vl, which is discriminated by the comparing means 6 and the count value of the abnormal frequency counting means 7 is counted up. When the above-described abnormal change of the sensor voltage SV frequently occurs within a predetermined time, the abnormal number N counted by the abnormal number counting means 7 within the preset time exceeds the abnormal number allowable value Nl, The determining means 9 determines that an abnormality has occurred in the sensor system. On the other hand, when the sensor voltage SV temporarily shows an abnormal change due to the influence of noise or the like, the abnormal number N does not exceed the abnormal number allowable value Nl, so that it is not judged as abnormal. Therefore, it is possible to detect an intermittent failure with a high frequency, that is, an intermittent failure that does not lead to a fixed failure but has a great influence on control.

〔Example〕

 Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram of an embodiment of the present invention, showing an example in which the present invention is applied to a control device mounted on an automobile, for example, an internal combustion engine control device.

In the figure, reference numeral 20 denotes a processor, a microprocessor 21, interfaces 22 and 23, and a ROM 24 for storing a sensor change voltage allowable value, an abnormal frequency allowable value, an abnormal determination level, various programs, etc. corresponding to each sensor. And RAM25 used for work area, etc., and standby used to store the error code when an error in the sensor system is detected.
Including RAM26. 30a to 30n are sensors, which are composed of a temperature sensor, a pressure sensor, an O ₂ sensor, and the like. This sensor 3
The output voltages of 0a to 30n are applied to the A / D converter 32 via sensor signal transmission systems 31a to 31n including lead wires, connectors, etc., where they are converted to digital sensor output voltages SVa to SVn and are interpolated. Microprocessor through face 22
Add to 21. The microprocessor 21 performs a known process based on the sensor output voltages SVa to SVn, and controls a fuel injection valve and the like (not shown) via the interface 23. Further, as will be described later, when an abnormality is detected in the sensor system and the abnormality is detected, for example, information on which sensor system has an abnormality is stored in the standby RAM 26 as an abnormality code, and an alarm device is issued via the interface 23. Drive 34.

In FIG. 2, reference numeral 40 denotes an automobile battery, the output voltage of which is directly applied to the constant voltage circuit 41 and is also applied to the constant voltage circuit 43 via the ignition switch 42, so that the output voltage V _SB of the constant voltage circuit 41 is _increased. The standby RAM 26 operates. That is, the standby RAM 26 is configured as a non-volatile memory that retains stored contents regardless of whether the ignition switch 42 is on or off. Also, a constant voltage circuit
The output voltage V _{CC of} 43 is supplied to other parts of the processing device 20, the sensors 30a to 30n, the A / D converter 32, and the like.

FIGS. 3 and 4 are flowcharts showing an example of the sensor system abnormality detection processing performed by the microprocessor 21, and FIG. 3 shows the processing performed each time the output of the A / D converter 32 is read.
FIG. 4 shows the processing of the failure diagnosis routine. still,
In FIGS. 3 and 4, the suffix “i” is the sensor 30.
The correspondence with i (i = a to n) is shown. Further, FIG. 5 is an explanatory diagram of an abnormality determination process of a sensor system related to one sensor, for example, the sensor 30a of FIG. 2, and FIG.
The time change of the sensor voltage SVa obtained by converting the output voltage of a into a digital amount by the A / D converter 32 and the abnormal determination voltage levels V _L and V _H that have been adopted in the past are also shown in FIG. b) shows the time variation of the sensor voltage SVa per unit time (sensor change voltage) ΔVa and the state of the sensor change voltage allowable value Vla. In the same figure (c), the sensor output voltage SVa is the sensor change voltage allowable value. The time change of the count value of the counter corresponding to the sensor 30a that is incremented each time the value Vla is exceeded and the state of the allowable number of abnormal times Nla are shown. FIG. 7D is provided in the standby RAM 26 corresponding to the sensor 30a. 7 shows a state of the failed display bit that has been set.

The operation of this embodiment will be described below with reference to the drawings.

At the sensor voltage acquisition timing, the microprocessor 21 corresponds to the sensor that should be acquired this time, and the A / D converter 32
, And the process shown in FIG. 3 is started.
For convenience of explanation, it is assumed that the sensor 30a is selected at this time.

The microprocessor 21 first compares the voltage SVa of the sensor 30a, which has been converted into a digital amount by the A / D converter 32, with the abnormality determination voltage levels V _H , V _L shown in FIG. Check (S1). Then, if the sensor output voltage SVa exceeds the level V _H or is smaller than the level V _L, it is assumed that an abnormality has occurred in the sensor 30a, and instead of the detected sensor output voltage SVa, the standard value stored in advance in the ROM 24 or the like is used. Perform fail-safe processing such as adoption (S2). At this time, the fail indication bit corresponding to the sensor 30a in the standby RAM 26 is set to "1" by a process not shown, and the alarm device 34 is driven.

On the other hand, when it is determined to be normal by the abnormality determination using the abnormality determination voltage levels V _H and V _L , the absolute value of the difference between the sensor output voltage SVa this time and the output voltage SVa of the previous sensor 30a (sensor change voltage) ΔVa Is calculated (S3), and this sensor change voltage ΔVa is compared with the sensor change voltage allowable value Vla shown in FIG. 5 (b) (S4). If the sensor change voltage ΔVa is larger than the sensor change voltage allowable value Vla, the sensor 30a corresponding to, for example, RA
The Na in the counter area set in M25 is incremented (S5), and the sensor change voltage ΔVa becomes the sensor change voltage allowable value.
If it is not larger than Vla, such processing is not performed.

The processing relating to the output voltage of the sensor 30a as shown in FIG. 3 is performed every time the output voltage of the sensor 30a is taken in, and such an operation is similarly performed for the other sensors 30b to 30n.

When the sensor output voltage SVa of the sensor 30a changes as shown in FIG. 5 (a), the sensor change voltage ΔVa is
As shown in FIG. 5 (b), the value Na in the counter area corresponding to the sensor 30a is incremented as shown in FIG. 5 (c) every time the sensor change voltage ΔVa exceeds the sensor change voltage allowable value Vla. Become.

Now, when the abnormality check timing set at a cycle of, for example, 1 minute (S10), the microprocessor 21 pays attention to the first sensor, for example, the sensor 30a (S11), and the value Na of the counter area corresponding to the sensor 30a is changed. It is determined whether or not it is larger than the allowable number of abnormal times Nla corresponding to the sensor 30a set in the ROM 24 (S12). If it is larger, fail-safe processing is performed as if frequent intermittent failures have occurred in the sensor system of the sensor 30a. After that (S13), the above counter area corresponding to the sensor 30a is cleared (S14), and if the value Na in the counter area is not larger than the allowable number of abnormal times Nla, it is assumed that no abnormality has occurred within this cycle. The contents of the counter area corresponding to the sensor 30a are cleared without performing the above fail-safe processing (S14). Note that step S13
As the fail-safe processing of, for example, the standard value set in the ROM 24 or the like is adopted instead of the output voltage of the sensor 30a, or the content of the fail display bit corresponding to the sensor 30a in the standby RAM 26 is set to "1", Alternatively, the operation of driving the alarm device 34 is performed. The example of FIG. 5C shows an example in which no abnormality is detected at the abnormality check timings T1 and T3, and an abnormality is detected at the abnormality check timing T2.

When the microprocessor 21 finishes the abnormality detection process for one sensor system, it determines whether or not all the sensors to be checked are finished (S15), and if it is finished, it proceeds to the other main process and is finished. If not, the focus is shifted to the next sensor system, the process returns to step S12 (S16), and the abnormality of the remaining sensor system is detected in the same manner as described above.

〔The invention's effect〕

As described above, according to the present invention, the number of times the change amount of the sensor voltage applied from the sensor via the sensor signal transmission system including the connector and the signal line exceeds the predetermined sensor change voltage allowable value. It is assumed that an abnormality has occurred in the sensor system when the number of times per predetermined time exceeds the preset abnormality count allowable value, even if the sensor voltage does not reach the abnormality determination level. Moreover, there is an effect that it is possible to detect an intermittent failure that greatly affects the control so that the voltage changes abnormally. Further, when the sensor voltage temporarily shows an abnormal change due to the influence of noise or the like, it is not judged as abnormal, so that erroneous detection due to noise or the like is eliminated.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of the configuration of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, and FIG. 3 is an example of processing of the microprocessor 21 performed every time when the output of the A / D converter 32 is read. A flow chart, FIG. 4 is a flow chart of a processing example of a failure diagnosis routine performed by the microprocessor 21, and FIG. 5 is an operation explanatory view of abnormality determination processing of a sensor system related to one sensor, for example, the sensor 30a in FIG. In the figure, 1 ... Sensor, 2 ... Processing device, 3 ... Sensor signal transmission system, 4 ... Sensor change voltage detection means, 5 ...
... sensor change voltage allowable value storage means, 6 ... comparison means, 7
…… Abnormal number counting means, 8 …… Abnormal number allowable value storage means, 9 …… Determination means, 20 …… Processing device, 21 …… Microprocessor, 22,23 …… Interface, 24 …… ROM, 25
…… RAM, 26 …… Standby RAM, 30a-30n …… Sensor,
31a, 31n ... Sensor signal transmission system, 32 ... A / D converter, 34 ...
… Alarm device, 40 …… Car battery, 41,43 …… Constant voltage circuit, 42 …… Ignition switch.

Claims (1)

[Claims] 1. A sensor system abnormality detecting device for detecting an abnormality of a sensor system comprising a sensor and a sensor signal transmission system for inputting an output voltage of the sensor to the processing device, wherein the processing device is provided in the sensor signal transmission system. Sensor variation voltage detection means for detecting a variation voltage of the sensor voltage introduced per unit time, a sensor variation voltage allowable value storage means for storing a tolerance value of the sensor variation voltage, and a sensor variation voltage detection means for detecting the variation voltage. Comparing means for comparing the sensor change voltage with the sensor change voltage allowable value, and abnormality number counting means for counting the number of times the sensor change voltage exceeds the sensor change voltage allowable value in the comparing means, Abnormal number permissible value storage means for storing the permissible value, and the abnormal frequency counted by the abnormal frequency counting means within a preset time is the abnormal frequency permissible number. Sensor system abnormality detecting device, wherein the sensor system is provided with a determination unit that an abnormality when exceeded.