Komatsu Corporation

Masahiro Funato

Tomohiro Nakagawa

Shigeru Yamamoto

Toshikazu Okada

A vehicle control system which is capable of performing a quick decelerating operation in all vehicle speed regions and setting a direct region where power from an engine is transmitted through a mechanical transmission unit only in a hydro-mechanical transmission. The vehicle control system includes an engine and a hydro-mechanical transmission and is designed to set a tractive force-vehicle speed characteristic corresponding to the direct region where power transmission from the input shaft to the intermediate output shaft of the hydro-mechanical transmission is done by the mechanical transmission unit alone in a specified engine speed region. An engine control system controls the engine and a decelerator outputs a deceleration command according to an operating amount thereof. The engine control system controls the engine to reduce engine output torque corresponding to a specified engine speed region in response to the deceleration command.

Vehicle control system

A variable relief valve is inserted in a hydraulic piping for connecting a first pump/motor to a second pump/motor. The variable relief valve is controlled such that when shifting the transmission from forward to reverse or vice versa, a relief set pressure of the variable relief valve is reduced in response to switching of a forward/reverse shifting clutch mechanism and after completion of the switching of the forward/reverse shifting clutch mechanism, the relief set value is increased.

Control system for a hydro-mechanical transmission

A vehicle control system having an engine and a hydro-mechanical transmission, which further comprises a decelerator for changing target engine speed according to the operating amount of a decelerator pedal; a hydrostatic transmission unit controlling means for controlling a hydrostatic transmission unit so as to make the actual speed of the engine coincident with the target engine speed; and engine controlling means for controlling the engine such that if the target engine speed is changed from a first target value to a second target value lower than the first target value by the decelerator, the output torque of the engine is reduced, while keeping the ratio of the amount of change in the output torque of the engine to the amount of change in the target engine speed constant or substantially constant.

Growing community of inventors

Hirakata, Japan

Masahiro Funato