JPS626855A - Fault diagnostic apparatus for vehicle - Google Patents

Abstract

PURPOSE:To enable quick and easy diagnosis work by inputting the vehicle condition information and predicting the symptom of vehicle while limiting only to the necessary fault information on the basis of said condition information. CONSTITUTION:The fault diagnosis apparatus for vehicle 21 comprises a means 9 for storing the cause/results information concerning to the fault of vehicle, means 11 for inputting the vehicle condition information and means 13 for inputting the symptom information. On the basis of the vehicle condition information to be inputted through input means 11, means 15 will limit the fault information to be stored in said means 9 only to the necessary information. While on the basis of the information inputted through the input means 13, predicting means 17 will search the fault information stored in said means 9 through said means 15 thus to predict the causes of faults and to inform the prediction results through informing means 19.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a vehicle failure diagnosis device that applies a so-called expert system.

[Description of Prior Art] In recent years, expert systems have come to be used in various fields including the medical field. Therefore, there is a desire to apply this expert system to construct a fault diagnosis device for vehicles.

However, when diagnosing vehicle failures, there are vehicle-specific circumstances, and there are difficulties in applying conventional expert systems as they are.

For example, a proposal for a vehicle fault diagnosis device to which a conventional expert system is applied as is is shown in FIGS. 4 and 5.

Figure 4 is a schematic diagram of the vehicle fault diagnosis device according to this proposal.
FIG. 5 is an example of a fault tree used in this device.

As shown in FIG. 4, the vehicle failure diagnosis device 1 includes a knowledge section 3 that stores information on causal relationships related to vehicle failures, and a knowledge section 3 that identifies the cause of the failure based on the symptoms occurring in the vehicle based on the information in the knowledge section 3. It consists of an inference section 5 that makes inferences, and an operation display section 7 that inputs symptoms into the inference section 5 and displays the inference results. The operation section 7 includes a keyboard 7a and a CRT 7b.
Equipped with etc.

The knowledge unit 3 provides cause information C(XY) indicating that cause Y is involved in symptom X as information on the causal relationship regarding the vehicle failure.
Inquiry information R(PY) for inquiring whether the phenomenon P is occurring based on the cause Y is included.

The contents of the knowledge section 3 can be expressed as a fault tree as shown in FIG. As shown in the figure, symptoms of engine stalling include "engine stalling when idling" x 1 and "engine stalling while driving JX2", and the cause of symptom XI is Yl, and symptom x
This indicates that Y2, Y3, and Y4 are possible causes of 2.

If causes Y2, Y3, and Y4 are true causes, then phenomena P2, P3 occur for these causes.

It also shows that P4 will occur respectively.

For example, if "engine stalling while driving" is set as symptom X, the inference unit 3 determines causes Y2 and Y3.

In order to infer Y4 and confirm its truth, the phenomenon P2,
We will interview P3 and P4 in sequence.

Then, inferences are made while narrowing down the parts and parts that are considered to be the cause of the set symptoms through the interview, and all the parts and parts that are thought to be the cause of the failure are reported as the inference results.

However, in the conventionally proposed vehicle fault diagnosis device as described above, it requires answers to all questions related to the vehicle condition (, Since all parts and parts are reported, the diagnostician requires a lot of effort and time to answer questions and check the cause of the notification, making the diagnostic work cumbersome.

[Object of the Invention] This invention improves the above problems, and provides a vehicle that can quickly and easily perform diagnostic work by limiting questioning and reporting of causes to only those that are necessary in consideration of the actual state of the vehicle. The purpose is to provide a fault diagnosis device for

[Summary of the Invention] In order to achieve the above object, the present invention, as shown in FIG. 1 as a claim correspondence diagram, includes a failure information storage means 9 that stores information on causal relationships regarding vehicle failures, and a failure information storage means 9 that stores information on the causal relationship regarding vehicle failures. The vehicle condition information input means 11 inputs vehicle condition information, the symptom information input means 13 inputs vehicle symptom information, and the vehicle condition information inputted from the vehicle condition information input means 11 is stored in the failure information storage means 9. failure information limiting means 15 for limiting the fault information contained in the information to only necessary information; and failure information storage means 9 via the failure information limiting means 15 based on the symptoms inputted from the symptom information inputting means 13.
an inference means 17 for searching failure information of and deducing the cause of the symptom, and a notification means 19 for notifying the inference contents of the means 17.
The vehicle fault diagnosis device 21 is constructed by having the following, and infers the cause of a set symptom in consideration of the actual condition of the vehicle.

[Description of Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 2 to 4. In this embodiment, vehicle status information is obtained from the vehicle control unit.

FIG. 2 is a block diagram of the vehicle fault diagnosis device shown together with the vehicle control section.

The control unit 23 of the vehicle includes a sensor group 25 that detects oxygen concentration, intake air factors, engine speed, water temperature, etc., and a sensor signal input unit 27 that inputs signals from the sensor group 25.
A vehicle control unit 3 receives the signal from the input section 27 and controls the engine and the like via the control signal output section 29.
1, a vehicle self-diagnosis device @35 that outputs a display signal to the LED display section 33, and a serial interface 37 connected to the vehicle self-diagnosis device 35.

The vehicle control unit 31 inputs the various sensor signals and outputs a fuel control duty signal, an ignition signal to the spark plug, an air flow rate control signal to the fuel system, and the like.

The vehicle self-diagnosis device N35 is connected to the sensor signal input section 2.
7, and determines whether there is an abnormality in the vehicle, such as "disconnection of water temperature sensor system" or "abnormal vehicle speed signal", and blinks the LED provided in the LED display section 33.

The serial interface 37 communicates the diagnostic status of the vehicle self-diagnosis device 35 to the outside, and it is possible to know the actual status of the vehicle, whether normal or abnormal, through the serial interface 37.

On the other hand, the vehicle failure diagnosis device 21a includes a serial interface 39 connected to the serial interface 37 via a plug, a knowledge section 41 that stores causal relationship failure information regarding vehicle failures, and a knowledge section 41 that stores causal relationship failure information regarding vehicle failures. , and an inference unit 43 connected to the serial interface 39.
and an operation display section 45 connected to the inference section 43.

The contents of the knowledge section 41 are the same as the contents of the knowledge section 3 shown in the conventional example. Further, the operation display section 45 is also the same as the operation display section 7 shown in the conventional example.

The reasoning section 43 has both the functions of the reasoning means 17 shown in FIG. 1 and the functions of the failure information limiting means 15. That is, the inference unit 43 limits the cause information and inquiry information held by the knowledge unit 41 to only necessary information based on the actual state of the vehicle input via the serial interface 39, and uses this limited information to quickly and They make accurate inferences.

Using the fault tree shown in FIG. 5 and using FIG. 3, the inference unit 4
The inference method used in step 3 will be explained.

Step 301 shows input processing of vehicle symptoms and vehicle conditions. Symptoms are entered through the keyboard 45a of the operation display section 45, and vehicle conditions are entered through the serial interface 39. Now, it is assumed that "Engine stalled while running JX2" is input as a symptom in the failure tree. It is also assumed that the vehicle status is "Injector normal" and "Control unit normal".

Step 303 shows failure inference processing.

Here, first, three causes are listed for the symptom of engine stalling while driving JX2, namely, the ignition system Y2, the fuel system JY3, and the intake air system JY4.

Step 305 shows a process of narrowing down the failure part based on the vehicle status information input via the interface 39. That is, here, the causes are Y2, Y3
, Y4, for which the phenomenon P is determined to be "normal" based on the input vehicle information, is not questioned and is deleted from the cause list. Therefore, in this example, where "injector normal" and "control unit, system normal" are obtained as vehicle status information, information regarding the causes of "ignition system" Y2 and "fuel system JY3" is deleted [engine stalls while driving]. Regarding the symptom JX2, only the cause ``intake air system JY4 remains.''

Step 307 indicates the end of the inference, that is, the process of determining whether the inference has reached a fault tree terminal.

Step 309 shows the interview process after the narrowing down process is performed in step 305. In the previous example, "Intake air system J
An inquiry phenomenon P4 related to Y4 is displayed on the CRT 45b such as "Is the air flow meter normal?".

The processing in steps 303 to 309 is repeated until a fault tree terminal is determined in step 311.

Step 311 indicates a failure part notification process. In the previous example, in response to the question ``Is the air flow meter normal?'', if the answer was ``abnormal,'' the cause would be determined to be ``intake air system JY4,'' and this would be displayed on the CRT.

As a result of the above, unnecessary information is wiped out, the content of the interview is significantly reduced, and inference processing becomes faster.

Note that in the above embodiment, the narrowing down process in step 305 was performed during the fault search, that is, after the cause information search, but this is for all phenomena that are determined to be "normal" before entering the inference process. Of course, the knowledge may be limited in advance.

Furthermore, in the above embodiments, the vehicle status information was input through the vehicle self-diagnosis device, but this is inferred by noting that the vehicle self-diagnosis process has already performed the primary processing and outputs only the results. This is done to reduce the load on the section 43, and it is possible to input control signals from the sensor signal input section 27 and/or the vehicle control unit 31 to process more advanced vehicle status information. be.

In addition, vehicle fault diagnosis equipment can be off-boarded (OFFBOAR).
D) It is of course possible to use it as a device.

[Effects of the Invention] As described above, the present invention is a vehicle fault diagnosis device that inputs vehicle status information and makes inferences by limiting the fault information to only necessary information, and therefore enables quick and easy diagnostic work. becomes.

[Brief explanation of the drawing]

Fig. 1 is a complaint correspondence diagram of the present invention, Fig. 2 is a block diagram of a vehicle failure diagnosis device showing an embodiment of the present invention, Fig. 3 is a processing flowchart of the inference section, and Fig. 4 is a conventional vehicle fault diagnosis device. FIG. 5, which is a block diagram of the fault diagnosis device, is an explanatory diagram of a fault tree used in conjunction with the explanation of the conventional example and the embodiment. 9...Failure information storage means 11...Vehicle status information input means 13...Symptom information input means 15...Failure information limiting means 17...Inference means 19...Notification means 21.21a...・Vehicle failure diagnosis device patent applicant
Nissan Motor Co., Ltd. 1rXJ

Claims (1)

[Claims] A failure information storage means for storing causal relationship information regarding vehicle failures, a vehicle state information input means for inputting vehicle state information, a symptom information input means for inputting vehicle symptom information, and the vehicle state information input means. failure information limiting means for limiting the failure information stored in the failure storage means to only necessary information based on input vehicle condition information; and failure information limiting means for limiting the failure information stored in the failure storage means based on the symptoms input from the symptom information input means. A vehicle fault diagnosis device comprising: inference means for searching the fault information in the fault information storage means through means to infer the cause of the symptom; and notification means for notifying the content of the inference of the means. .