JPS6235917A - On-vehicle electronic controller - Google Patents

Abstract

PURPOSE:To prevent the malfunction of function which copes with abnormality to be generated based on erroneous diagnosis by not diagnosing a sensor circuit system and an actuator circuit system when a supply voltage is lower. CONSTITUTION:When the trouble diagnostic processing is started, old data is cleared, and initial values are set to prescribed registers. Before practical trouble diagnosis, an output A of a supply voltage discriminating circuit 40 inputted to a port P5 is checked to judge whether the supply voltage is normal or not. A voltage reduction detection signal is generated in the output A if the supply voltage is lower than the reference value which secures the normal operation of the sensor circuit system and the actuator circuit system, and the voltage reduction detection signal is generated in an output B if the supply voltage is lower than the second reference value lower than said reference value. The voltage reduction detection signal from the output B of the supply voltage discriminating circuit 40 acts upon a reset circuit 24 to reset a microcomputer 20, thus stopping the program executing operation.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electronic control device that controls various functional parts of a vehicle, particularly an automobile, and particularly to an electronic control device for detecting an abnormality in a sensor circuit system or an actuator circuit system. Concerning improvements in fault diagnosis technology.

[Conventional technology]

Fig. 3 shows a schematic configuration of a conventional vehicle electronic control unit (for example, Nissan Technical Report 1982 Edition 18°62-63).
(see page).

In FIG. 3, 10 is a battery that is a power source for vehicle electrical components, 12 is an ignition switch, 14 is a starter switch, 16 is a starter relay, 18 is a starter, and 20 is a microcomputer (hereinafter referred to as microcomputer) that is the center of the electronic control unit. 22 is a power supply circuit that provides a stabilized power supply voltage to the microcomputer 20.

The microcomputer 20 reads a detection signal from a sensor 26 that detects the state of the vehicle and environmental conditions, and uses the detection signal to drive an actuator 30 that controls a specific function of the vehicle via an output circuit 28. - To explain the constant speed driving control function as an example, the sensor 26 is a vehicle speed sensor, the actuator 30 is a throttle actuator, the microcomputer 20 reads the vehicle speed data detected by the vehicle speed sensor 26, and the vehicle speed matches the specified vehicle speed. The throttle actuator 30 is driven so as to open and close the throttle valve as appropriate to control the vehicle speed. Various other functions are electronically controlled, and the microcomputer 20 reads detection signals from various hinges 26, uses them to drive various actuators, and controls various functions of the vehicle. This is normal.

In addition, the microcomputer 20 has a fault diagnosis function that is the object of the present invention (it executes a fault diagnosis routine in parallel with the main routine), and in addition to this fault diagnosis function, it also has a seven-factor safety circuit 34. It is provided. The failsafe circuit 34 includes a program abnormality detection circuit 36 that monitors runaway of the microcomputer 20, and an input/output abnormality detection circuit 38.
Contains. The detection signal of the sensor 26 is input to the input/output abnormality detection circuit 38, and the actuator 3
A signal representing the driving state of the actuator 30 is inputted through a current detection resistor 41 connected in series with the actuator 30.

The reset circuit 24 is a circuit that generates a reset signal for the microcomputer 2o, and resets the microcomputer 2o when the stabilized output of the power supply voltage 22 is below the reference ffi, and also resets the microcomputer 2o when an abnormality detection signal is issued from the failsafe circuit 34. Also reset the microcontroller 2°.

Reference numeral 32 denotes a warning lamp, and when any abnormality is detected by the failure diagnosis process of the microcomputer 2o, the warning lamp 32 is driven to turn on depending on the content of the abnormality.

FIG. 4 is a flowchart showing the procedure of the above-mentioned failure diagnosis process by the microcomputer 20. When the fault diagnosis process is started, first, the registers and memory used for this process are cleared (401), and initial values necessary for the process are set in predetermined registers (402). Next, the detection signal of the sensor 26 is read from the boat P2 (403), and it is determined whether the read value is within the normal range (404).
).

If the sensor circuit system is normal, next, a signal is sent from P/P to the output circuit 28 to drive the actuator The square load state detection signal is read from the boat P3 (406), and it is determined whether the signal is within normal knots (407). If the actuator circuit system is also normal, the failure diagnosis process ends.

Whether the sensor circuit system is determined to be abnormal in step 404,
If it is determined in step 407 that the actuator circuit system is abnormal, the process proceeds to step 408 to memorize the abnormal location, and in the next step 409, the warning lamp 32 is driven to display the abnormal state and 7. Drive the circuit.

[Problems that the invention attempts to solve]

-F In the conventional electronic control device described above, for example, when the starter switch 14 is turned on immediately after the ignition switch 12 is turned on to operate the starter 18, a large current flows through the starter 18, so that the power supply voltage of the battery 10 decreases. The voltage may suddenly drop below the reference voltage that guarantees normal operation of the sensor circuit system and actuator circuit system. Even in this state, the power supply circuit 22
is provided, the stabilized power supply voltage supplied to the microcomputer 20 does not drop much, and the reset circuit 2
4 may not be reset.

When the microcomputer 20 executes the failure diagnosis process under the above circumstances, even if the sensor circuit system and actuator circuit system are normal, the power supply voltage of these circuit systems may fall below the reference value that guarantees normal operation. Step 4
04 or step 407, and steps 4'08 and 409 are executed to turn on the warning lamp 32.
An abnormality response action such as lighting up is performed. In other words, malfunctions may occur due to misdiagnosis.This invention was developed in view of the above-mentioned problems with the conventional technology. An object of the present invention is to provide a vehicle electronic control device that can accurately diagnose whether a circuit system or an actuator circuit system is normal or abnormal.

[Means for solving problems]

Therefore, the present invention includes a power supply voltage discrimination means for detecting whether the power supply voltage applied to the sensor circuit system and the actuator circuit system is less than or equal to a reference value that guarantees normal operation of these circuit systems. , a failure that operates only during a period when the power supply voltage is detected to be equal to or higher than a reference value by this discrimination means, and checks the operation of the sensor circuit system J3 and the actuator circuit system to detect whether it is normal or abnormal. Diagnostic means were installed.

(Effect) The battery voltage decreases by not operating the starter,
If the power supply voltage is determined to be below the reference value by the above power supply voltage discrimination means,
During this period, the failure diagnosis means does not substantially operate, and therefore the sensor circuit system and the actuator circuit system are not erroneously diagnosed as abnormal.

〔Example〕

FIG. 1 shows the hardware configuration of a vehicle electronic control device to which the present invention is applied, and FIG. 2 is a flowchart of a failure diagnosis routine executed by the microcomputer 20 in FIG.

In the illustrated hardware configuration, the difference between the configuration of the present invention shown in FIG. 1 and the conventional configuration shown in FIG. 3 is that the one shown in FIG.
is input to the port P5 of the microcomputer 20, and another output signal B is input to the reset circuit 24. Other hardware components are the same as in FIG. 3, and corresponding parts are designated by the same reference numerals as in FIG. 3, and their explanation will be omitted.

The power supply voltage discrimination circuit 40 is a circuit that discriminates the level of the voltage of the battery 10, and when the power supply voltage falls below a reference value that guarantees normal operation of the sensor circuit system and the actuator circuit system described in 5L, the output A is output. A voltage drop detection signal is generated at the output B, and when the power supply voltage becomes lower than a second reference value that is lower than the reference value, a voltage drop detection signal is generated at the output B.

When the power supply voltage becomes lower than the second reference value, the power supply circuit 22
The stabilized power source supplied to the microcomputer 20 from the current level also decreases rapidly (the second reference value is selected accordingly). The voltage drop detection signal from the output B of the power supply voltage discrimination circuit 40 acts on the reset circuit 24, and the micro combi coater 20
Reset () to stop program execution.

The voltage drop detection signal from the output of the power supply voltage discrimination circuit 40 acts on the failure diagnosis process (FIG. 2) executed by the microcomputer 20 as follows.

As shown in FIG. 2, when the fault diagnosis process is started, old data in predetermined registers is cleared (201) and initial values are set in the predetermined registers in the same way as explained in FIG. (202).

Next, before performing a substantial failure diagnosis, the output A of the power supply voltage discrimination circuit 40 input to the boat P5 is checked to determine whether or not the power supply voltage is normal (203).

If the power supply voltage is normal, the process proceeds to step 204 and subsequent steps to perform a substantial failure diagnosis, but if the power supply voltage has decreased abnormally, the process returns from step 203 to step 202 and steps 202 and 203 are repeated. In other words, the process proceeds to step 204 and subsequent steps only when the power supply voltage is normal.

Steps 204 to 208 are steps 203 to 2 in FIG.
07, the detection signal of the sensor 26 is read to determine whether it is normal or abnormal, and the actuator 30 is driven to read the load status signal to determine whether it is normal or not.

If it is determined that the sensor circuit system or the actuator circuit system is abnormal, the process proceeds to step 209 where the abnormal location is memorized, and in the next step 210, countermeasures such as displaying the abnormal state with the warning lamp 32 are performed.

Furthermore, even while the actual diagnostic operations in steps 204 to 208 are being executed, if a voltage drop detection signal is generated from the output A of the power supply voltage discrimination circuit 40, the signal acts as an interrupt signal to the microcomputer 20. ), the execution step of the microcomputer 20 is forcibly returned to step 202. In other words, the failure diagnosis operation is stopped and steps 202 and 203 are repeated until the power supply voltage is restored. After the power supply voltage is restored, the failure diagnosis from step 204 onwards is executed again.

〔Effect of the invention〕

As explained in detail above, in the vehicle electronic control device according to the present invention, when the power supply voltage has decreased to the point where the sensor circuit system and the actuator circuit system cannot operate normally, these circuit systems Since no fault diagnosis is performed, there will be no misdiagnosis due to a drop in electric mN pressure and no malfunction of the abnormality handling function based on the misdiagnosis, and the reliability of this kind of fault diagnosis function will be improved compared to the conventional one.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the hardware configuration of a vehicle electronic control device according to an embodiment of the present invention, FIG. 2 is a flowchart of a failure diagnosis routine executed by the microcomputer 20 in FIG. 1, and FIG. J block diagram showing the hardware configuration of a conventional electronic control device, No. 4
The figure is a flowchart of a fault diagnosis routine executed by the microcomputer 20 in FIG. 10... Battery 20... Microcomputer 22... Power supply circuit 26... Sensor 28.
...Output circuit 30...Actuator 32...
・Warning lamp 42...Power supply voltage discrimination circuit

Claims (1)

[Claims] (1) In a vehicle electronic control device that drives an actuator that controls a specific function of the vehicle using a detection signal from a sensor that detects the state of the vehicle or environmental conditions, the signal that is applied to the sensor circuit system and the actuator circuit system is power supply voltage discrimination means for detecting whether or not the power supply voltage is equal to or higher than a reference value that guarantees normal operation of these circuit systems; What is claimed is: 1. A vehicle electronic control device comprising: a failure diagnosis means that operates only during a period of time and checks the operation of the sensor circuit system and the actuator circuit system to detect whether the sensor circuit system and the actuator circuit system are normal or abnormal.