JPH02185651A - Device for diagnosing failure of vehicle - Google Patents

Abstract

PURPOSE:To carry out rapid and sure diagnosis by judging to be the abnormality of an air system when the rate of change of engine speed at the time of controlling a throttle valve from total closing to full opening is below a reference value with the engine speed being above a reference value, while judging to be the abnormality of an air-fuel ratio system when the engine speed is below the reference value. CONSTITUTION:An engine speed signal operating/processing means 31 and a throttle valve detecting means 32 are included in a signal detecting means 3. Also, reference values for judging each failure system based on the engine speed and the rate of change thereof at the time of varying a throttle valve from a closed condition to an open condition are stored on a reference value memory means 6. When the detected engine speed is below the reference value, judgment is formed to be the nonconformity of an MR system. On the other hand, when the detected engine speed is above the reference value, judgment is formed to be the nonconformity of an air system. Thereby, the system in failure can be surely diagnosed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vehicle failure diagnosis device suitable for diagnosing a failure system of a vehicle.

(Prior Art) In recent years, as electronic control systems for automobiles have become more sophisticated and complex, the systems are becoming more and more black boxes, and malfunction phenomena themselves are also becoming more complex. Therefore, unless you are familiar with the system specifications 2 functions, it is difficult to make a quick and reliable diagnosis.

On the other hand, current automobile failure diagnosis largely relies on the knowledge and experience of service personnel at repair shops, but the system specifications of automobile electronic control systems are gradually updated to improve performance and add new functions. It has been changing.

In response to the speed of changes in specifications, service personnel are now required to make great efforts to understand these electronic control systems.

Therefore, a diagnostic system using AI (artificial intelligence) has been introduced as a device that provides highly specialized knowledge to service personnel (Automotive Technology, Lol, 40. No. 2
(see 1986).

Further, an example of this type of device previously proposed by the present applicant is shown in FIG. 4 (see Japanese Patent Application No. 111428/1982).

Now, to explain its basic configuration based on the same figure, the input means 1 uses a keyboard or the like, the type of car 9 to be diagnosed, the engine type 1, the details of the rare inspection (for example, one-year statutory inspection, engine failure diagnosis, etc.). ) and the name of the owner of the car.

The input means 2 is kept by the service person and is used to send information from the service person to the device and to display information from the device. Although the display on the input means 2 is auxiliary to the display means 7, which will be described later, if it is provided, it is also possible to omit the display means 7 and perform all display functions on the input means 2.

Further, the signal detection processing means 3 includes sensors that detect the functions of each part, each part, and each system of the car, and a signal processing circuit that performs processing such as shaping and amplification so that the signals of the sensors can be inputted to the computer 4. Alternatively, it may include a signal processing circuit that processes sensor signal information and actuator drive signal information used by the engine control unit so that they can be input to the computer 4.

The computer 4 has at least Ilo and ROM.

It is configured with RAM and CPU and controls this device.

It performs calculation 1 judgment and controls peripheral input/output devices. Note that various types of Ilo, ROM, RAM, and CPU are used depending on the scale and processing performance, such as those that are all mounted on one chip, and those that are individually separated.

The diagnostic procedure storage means 5 stores the contents and instruction procedures to be given to a service person in order to diagnose, for example, the function of the ignition system or the function of the fuel system of the engine, and how to judge the actual human-powered signals. The procedure is also memorized. Then, the CPU of the computer 4 issues a command to control the peripheral devices according to this procedure.

The reference value storage means 6 stores reference values such as normal, failure, and caution for each car model and engine type, and the CPU of the computer 4 follows the procedure of the diagnostic procedure storage means 5.
Diagnosis is performed by comparing the value measured by the signal detection processing means 3 with the reference value.

The display means 7 is generally a CRT or the like, and this device projects the content to be displayed to the service person. For example, monitor the contents input by the input means 1.

Contents of instructions to service personnel, monitoring of measured values, display of diagnostic results, etc. are performed. In addition, as mentioned above, when the displayable range of the human power means 2 is wide, it is sometimes omitted.

The recording means 8 is capable of hard copying, such as a printer, and prints out the measurement value 1 diagnosis result and vehicle information as necessary.

(Problems to be Solved by the Invention) However, in the conventional devices as described above, for example, in the diagnosis system using AI described in the former "Automotive Technology", the dialogue format is based on an interview. For,
There has been a problem in that it is not possible to accurately diagnose the location of the failure unless accurate responses to questions are given.

In other words, for example, in response to engine failure symptoms such as ``unstable idle'' and ``poor drivability,'' the air system (
Is there a problem with the AAC valve, air regulator, etc.?
If the MR system (mixing ratio of air and fuel) cannot accurately respond to the problem, there is a problem in that it is impossible to diagnose individual failure points in subsequent processing.

In cases like this, service personnel have traditionally relied on their experience and intuition cultivated over many years, but if incorrect information is input into the AI system, incorrect diagnosis results may be output, or the exact location of the failure may be incorrectly determined. There was a problem in that it took a lot of time to diagnose the problem.

In addition, in the latter case described in Japanese Patent Application No. 57-111428, items that can be reliably determined in the failure diagnosis process are displayed on that line, and items that cannot be determined are displayed using input information obtained or possible judgments. However, there is a problem in that it is not possible to determine whether the problem is with the air system or the MR system in the above example. Ta.

(Object of the Invention) In view of the above problems, this invention aims to solve the problem of air system failure or MR.
To provide a vehicle failure diagnosis device that can reliably determine whether there is a problem with the system (air-fuel ratio) and can smoothly proceed with subsequent diagnosis.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides an engine rotation speed calculation means for calculating the engine rotation speed based on an engine rotation signal, and a throttle valve that changes the throttle valve from fully closed to fully open. a rate of change calculating means for calculating a rate of change in the engine speed for each predetermined time based on the calculated engine speed when controlling the engine speed; a reference value storage means storing respective rotational speeds; and when the rate of change in the engine speed per predetermined time when the throttle valve is controlled from fully closed to fully open is equal to or less than the reference rate of change; a first determining means that determines that there is an abnormality in the air system when the engine rotation speed is equal to or higher than the reference rotation speed; and a second determining means that determines that there is an abnormality in the air-fuel ratio system when the engine rotation speed is lower than the reference rotation speed. It is characterized by being

(Explanation of Examples) Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

In addition, this example examines malfunction symptoms such as "unstable idling" and "poor drivability" in a vehicle with an engine failure. , air regulator, etc.) or the MR system (mixture ratio of air and fuel).

Fig. 1 shows the basic configuration of this embodiment, but since it is almost the same configuration as Fig. 4 showing the conventional example, the same components are given the same reference numerals and their explanations are omitted. do.

In the case of this embodiment, the difference from the conventional example is that the signal detection processing means 3 includes an engine rotation signal calculation processing means for calculating the engine rotation speed and its rate of change by detecting the engine rotation signal. 31, and throttle valve detection means 3 for detecting the open/closed state of the throttle valve.
2 is included.

In this example, the reference value storage means 6 also stores reference values for fault system discrimination based on the engine speed and its rate of change when changing the throttle valve from the closed state to the open state. As will be described later, when the engine speed and its rate of change are calculated, the system is configured to diagnose a failure system while referring to the stored reference value.

On the other hand, FIG. 2 shows the change in engine speed when the throttle valve is changed from a fully closed state to a fully open state in a case where there is a problem in the air system and a case where there is a problem in the MR system.

As shown in FIG. 6(a), when there is a problem with the air system, the throttle valve changes from a fully closed state to a fully open state.

The engine speed rises smoothly from time to time t2 as shown by arrow A.

On the other hand, if the MR system is defective, as shown in Figure (b),
The engine speed is up to 5, same as when there is a problem with the air system.
50 Orpm < 0, which corresponds to a fully open throttle state, but the rise of the engine speed between t3 and t4, when the throttle valve changes from fully open to fully open, is not smooth as shown by arrow B.

That is, there is a difference in the displacement of the engine speed when the throttle valve is changed from fully open to fully open when the air system is malfunctioning and when the MR system is malfunctioning.

Therefore, the reference value NR of the engine speed and the base heavy chain NR□ (for example, a value near zero) of the rate of change in the engine speed are set in advance for determining the fault system when the throttle valve is changed from the fully open state to the fully open state. The stored reference values NR and NR1 are stored in the reference value storage means 6, and while referring to the stored reference values NR and NR1, it is determined whether the air system is at fault or the MR system is at fault based on the detected engine speed change rate and engine speed. This embodiment attempts to determine the following.

In addition, in this example, AAC
This includes valves, air regulators, etc., and assumes that malfunctions in the MR system include, for example, deterioration of the characteristics of the air flow meter, clogging of the injector, and poor fuel control of the pressure regulator.

Hereinafter, the processing procedure for the above-described determination executed within the computer 4 will be explained based on the flowchart of FIG.

That is, when predetermined initial information is input to the input means 1 and the program is started, it is first checked from the detection result of the throttle valve detection means 32 whether or not the throttle valve is fully open (chip 100).

Here, if the throttle valve is not in the fully closed state (NO in step 100), instruct the service engineer to output the message "Please put the throttle valve in the fully closed state" on the CR7 screen of the display means 7 (step 110). do.

As a result, the service person sets the throttle valve to the fully open state by operating the keys on the input means 2 or the like.

Thereafter, when the fully closed state of the throttle valve is confirmed by the detection result of the throttle valve detection means 32 (step 100
(YES), then the display means 7 displays the message ``Please open the throttle valve fully'' and instructs the service engineer (step 120).

Then, when the fully open state of the throttle valve is confirmed by the detection result of the throttle valve detection means 32 (step 130
(Yes), the engine speed and its rate of change when the throttle valve changes from fully open to fully open are calculated, and based on the calculation results, it is determined whether the problem is with the air system or the MR system. will be done.

That is, in the next step 140, first, the rate of change Ni'' of the engine speed is calculated. That is, if the engine speed manually applied every ti is RPMi, the rate of change (differential value) Nt' of the engine speed is It is determined by the following formula.

Ni=RPMi-RPM, -, /1i-t, -1 This value is then compared with the reference value NR stored in the reference value storage means 6 in advance.

Here, the detected engine speed change rate Nt' is N
If it is greater than RI (NO in step 140), it is determined that the engine is rotating smoothly.

On the other hand, if Ni'' is less than or equal to NRI (Y in step 140)
ES), the engine rotation speed at that time is detected, and in the subsequent step 150, it is determined from this rotation speed whether the problem is caused by the air system or not.
It is possible to check whether the problem is caused by the R system.

Here, to determine whether the problem is with the air system or the MR system,
It is checked whether the engine rotational speed Ni is equal to or greater than a predetermined reference value N8 when Ni' is equal to or less than NR1. In addition, the standard value N
It is assumed that R is determined based on a value near the engine speed of the performance limit in consideration of the rev limit as the maximum engine speed, or a value near the engine speed when performing a fuel cut.

If the detected engine speed Ni is smaller than the reference value NR (YES in step 150), it is determined that there is a malfunction in the MR system.

On the other hand, if the detected engine speed Ni is equal to or higher than the reference value N8 (NO in step 150), it is determined that there is a problem in the air system. In other words, if there is a failure in the engine and the phenomenon is assumed to be in the air system or MR system, if the rate of change in engine speed is below the reference value NRI and the engine speed is above the reference value N8, then Since it seems that the rotation speed increases smoothly, it is considered to be a problem with the air system. Also, the rate of change in engine speed is the standard value N8□
If the rotational speed in the following cases is smaller than the reference value NR, it is considered that the rotational speed does not increase smoothly, and this is considered to be a malfunction in the MR system.

As described above, this embodiment device includes an engine rotation signal calculation processing means 31 that detects an engine rotation signal and calculates the engine rotation speed and its rate of change, and a throttle valve detection means 32 that detects the open/closed state of the throttle valve. and
The reference value storage means 6 is configured to store in advance a reference value for determining a failure system based on the engine speed and its rate of change when the throttle valve changes from a fully closed state to a fully open state.

For this reason, the engine speed and its rate of change when the throttle valve changes from fully closed to fully open are calculated, and it is determined whether the engine speed is equal to or higher than the reference value NR when the rate of change is less than or equal to the reference value NR1. By making this distinction, it is possible to reliably detect whether the problem is with the air system or the MR system.

In addition, as described above, it is possible to determine whether the problem is in the air system or the MR system without relying on the experience or the five senses of the service personnel, so in subsequent diagnosis, only the parts caused by each system need to be examined. This will allow subsequent diagnosis to proceed smoothly.

(Effects of the Invention) The vehicle failure diagnosis device according to the present invention is provided when the rate of change in the engine speed per predetermined time when the throttle valve is controlled from fully open to fully open is equal to or less than the reference rate of change,
If the engine speed at that time is higher than the reference speed, it is determined that there is an air system abnormality, and if it is lower than the reference speed, it is determined that the air-fuel ratio system is abnormal. , it is possible to reliably determine whether there is a problem with the air system, and the failure system can be reliably diagnosed.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the basic configuration of the present invention, Fig. 2 is an engine speed characteristic diagram corresponding to the throttle valve opening when the air system is malfunctioning and when the MR system is malfunctioning. A flowchart showing the processing procedure of the embodiment, and FIG. 4 is a block diagram showing the basic configuration of the device in the conventional example. 1.2...Input means 3...Signal detection processing means 4...Computer 5...Diagnostic procedure storage means 6...Reference value storage means 7...Display means 8...Storage means 31 ...Engine rotation signal calculation processing means 32...Throttle valve detection means Fig. 1 Patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Scope of Claims] 1. Engine rotation speed calculation means for calculating the engine rotation speed based on an engine rotation signal, and a predetermined time based on the calculated rotation speed when the throttle valve is controlled from fully closed to fully open. a rate of change calculating means for calculating a rate of change in the engine speed for each time; a reference value storage means for storing a value near zero as a reference rate of change; and a maximum engine speed as a reference speed; When the rate of change in the engine speed per predetermined time period when controlling the valve from fully closed to fully open is less than or equal to the reference rate of change, and when the engine speed at that time is greater than or equal to the reference speed, the air system A vehicle failure diagnosis device comprising: a first determining means for determining an abnormality in the rotation speed; and a second determining means for determining an abnormality in the air-fuel ratio system when the rotation speed is smaller than the reference rotation speed.