Denso Corporation

Nippondenso Co., Ltd.

Hideyuki Ohashi

Hiroshi Shibata

Sanae Hirata

Kazuhiro Nishigaki

Nobuhiro Takano

Kuraji Kato

An electronic control system has an engine control computer and a throttle control computer. The engine control computer has a monitor program separate from an engine control program. The monitor program is for checking the operation of the throttle control computer and executed by the engine control computer as a timer interrupt routine. A watch dog timer is connected to the engine control computer to detect malfunction of the monitor program in response to a watch dog pulse produced during the execution of the monitor program. The watch dog timer disables an electronic throttle control by the throttle control computer upon detection of the malfunction of the monitor program. At the same time, the engine control mode is changed from a normal engine control to an engine power reduction control thereby to ensure a limp-home operation of the engine.

Electronic control system and method having monitor program

When transistors are switching-controlled by a microcomputer, on the basis of the absolute value of a value obtained by subtracting an actual opening angle value from an instruction value generated from the microcomputer for the opening angle of a throttle valve serving as a driven apparatus which is driven by a d.c. motor, a current flowing through each of resistors detected by comparators, and voltages at both ends of a resistor detected via each of the buffers, the microcomputer determines an abnormality in the d.c. motor and the throttle valve and an abnormality in the transistors or the power supply path while distinguishing those from each other.

Apparatus for detecting abnormality in direct current motor driving

A throttle control CPU drives an electric motor throttle valve control based on an accelerator position. When detecting an abnormality in the throttle opening control system, a main CPU stops driving the electric motor and controls fuel injection amount and/or ignition timing to curb engine output torque increases otherwise caused by a valve opening movement (performed until a cooperative member connected to the throttle valve contacts a restricting member mechanically connected to the accelerator pedal). Thereafter, opening of the throttle valve is regulated according to the accelerator pedal position while the restricting member and the cooperative member remain in contact. The control apparatus smoothly shifts the throttle opening regulation to the fail-safe mode when an abnormality occurs by actively controlling engine speed changes during mode transition.

Growing community of inventors

Toyota, Japan

Hideyuki Ohashi