Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – With indicator or control of power plant
Reexamination Certificate
1999-03-04
2001-05-08
Dolinar, Andrew M. (Department: 3747)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
With indicator or control of power plant
C701S114000, C123S396000, C700S004000, C700S081000
Reexamination Certificate
active
06230094
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application relates to and incorporates herein by reference Japanese Patent Application No. 10-101127 filed on Apr. 13, 1998.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic control system which is capable of detecting a computer malfunction by monitoring operations of a plurality of computers with respect to each other.
2. Related Art
Electronically-controlled throttle devices, which drive throttle valves by electric motors, are used recently in automotive vehicles. JP-A-6-83659 discloses a method of detecting malfunction of microcomputer (computer) for such electronically-controlled throttle devices. According to this malfunction detection method, a plurality of computers communicate and compare each other's various calculation data and A/D conversion data, which are produced in each computer in the same calculation and A/D conversion processing, so that the computer malfunction may be detected based on the comparison of data.
It is, however, impossible to determine which one of the computers are in failure when two computers is used in the system. Therefore, both computers will have to be disabled for a fail-safe operation upon detection of the malfunction.
For instance, recent electronic control systems for engines use a computer for a throttle control as well as a computer for an engine control (spark ignition and fuel injection control). In those systems, even if only the computer for the throttle control fails, both computers have to be disabled to control the spark ignition and fuel injection. As a result, a limp-home operation is not sufficiently ensured.
To overcome the above disadvantage, an additional computer for monitoring other computers may be used, or a watch dog timer (WDT) may be added to the engine control computer. The additional computer will add cost. Further, the engine control computer will not be able to detect the malfunction of a monitor program of the throttle control computer by only the watch dog timer of the engine control computer in the event that only the monitor program of the throttle control computer fails.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an electronic control system, which is capable of obviating the above problem.
It is a further object of the present invention to provide an electronic control system, which is capable of attaining a limp-home operation of an engine control computer even when a throttle control computer has a malfunction.
According to the present invention, a first computer is designed for controlling a first object such as a throttle driving motor, and a second computer is designed for controlling a second object such as a fuel injection or ignition timing of an engine. The second computer has a monitor program for monitoring operation of the first computer. The second computer executes the monitor program as a timer interrupt routine, which interrupts another routine such as an engine control program. The second computer produces a watch dog pulse during the execution of the monitor program. A watching unit is connected to the second computer to detect a malfunction of the monitor program from the watch dog pulse. The watching unit disables the throttle driving motor control and at the same time applies a malfunction signal to the first computer, which in turn transmits it to the second computer. The second computer changes its engine control mode from normal control to a power reduction control, thereby ensuring a limp-home operation of the engine without throttle control by the first computer.
REFERENCES:
patent: 4532594 (1985-07-01), Hosaka et al.
patent: 4558416 (1985-12-01), Pauwels et al.
patent: 5880568 (1999-03-01), Bederna et al.
patent: 5-81222 (1993-04-01), None
patent: 6-83659 (1994-03-01), None
patent: 6-274468 (1994-09-01), None
Kato Kuraji
Ohashi Hideyuki
Shibata Hiroshi
Denso Corporation
Dolinar Andrew M.
Nixon & Vanderhye P.C.
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