Nippondenso Co., Ltd.

Denso Corporation

Shinnosuke Hayashi

Hiroshi Shibata

Mitsuru Ban

Isao Osuka

Keiji Sugai

Satoru Sasaki

In an ECU for controlling an engine, a microcomputer executes a program in a mask ROM after releasing the reset, determines a signal of a specific input terminal, and switches in accordance with the foregoing determination result the self operation mode into either one of the normal mode to execute a control program in a flash ROM and the rewrite mode to update and write a data from an external unit into the ROM. A monitor circuit monitors a watchdog pulse from the microcomputer, outputs a reset pulse to the microcomputer when determining an abnormality, and alters the level of the foregoing signal to the microcomputer into the level of the normal mode into the level of the rewrite mode.

Electronic control unit and method having program rewriting function

An engine control program is not overwritten when an engine of a vehicle is in operation even if a memory writer sends an engine write request to an engine controller. When an operator stops the engine and the memory writer again requests to overwrite the engine control program, the engine controller receives a write control program from the memory writer and executes the same. After that, the engine controller starts a new engine control program after its CPU is reset. Therefore, since the engine is at a stop during the overwriting of the engine control program, there will be no unexpected operations in the mechanism of the vehicle even though the control program and data are changed.

Program/data overwriting control after machine stop

At diesel engine startup, a fuel injection control system for the diesel engine injects a pre-jet of fuel into a combustion chamber in synchronism with a signal indicative of an angular position of the crankshaft of the diesel engine. After the pre-jet of fuel has been injected, the fuel injection control system injects a main jet of fuel which is larger in quantity than the injected pre-jet of fuel. Even when the engine rotational speed is low and subjected to variations as at engine startup, the pre-jet of fuel is reliably injected into the combustion chamber at a desired time. The pre-jet of fuel which is injected and ignited prior to the main jet develops an easily ignitable, activated condition in the combustion chamber. The subsequently injected main jet of fuel can thus be easily ignited by the activated condition in the combustion chamber. The diesel engine can be started quickly and smoothly without fail.

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Nukata-gun, Japan

Shinnosuke Hayashi