US 5,162,995 AGranted

Hydraulic active suspension system for a vehicle performing vehicle height feedback control

AssigneesToyota Jidosha Kabushiki Kaisha, Aisin Seiki Kabushiki Kaisha

InventorsHiroyuki Ikemoto, Shuuichi Buma, Toshio Aburaya, Takashi Yonekawa, Toshio Onuma, Tsukasa Watanabe, Toshiaki Hamada

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Abstract

In a hydraulic active suspension system, a plurality of actuators having working fluid chambers are provided corresponding to the vehicle wheels. Each actuator is adapted to increase and decrease vehicle height in response to the pressure within its working chamber, which is controlled by a pressure control device. Vehicle speed and vehicle heights at the locations corresponding to the vehicle wheels are detected by corresponding sensors. A control device is further provided for controlling the pressure control device so that the pressures within the working fluid chambers are driven to substantially the desired pressures, the desired pressures determined by, at least, the sum of the first control parameters corresponding to the differences between the actual vehicle heights detected and the associated desired vehicle heights and the second control parameters corresponding to the changing amounts of the vehicle height differences. The second control parameters are so set that the higher the vehicle speed is, the higher the second quantities are in magnitude, enhancing the controllability and stability of the vehicle under higher vehicle speed conditions and ensuring a greater comfortability level of the vehicle under lower vehicle speed conditions.

Claims9

Dependent claims

A hydraulic active suspension system for a vehicle having a vehicle body and a plurality of vehicle wheels comprising:

a plurality of actuators each having a working fluid chamber and being provided between said vehicle body and an associated one of said plurality of vehicle wheels, each actuator adapted to increase and decrease vehicle height in response to a pressure within its working fluid chamber;
pressure control means for controlling the pressures within said working fluid chambers;
vehicle speed detecting means for detecting a vehicle speed and generating a vehicle speed signal indicative of the vehicle speed;
and
second control means for controlling said pressure control means so that an actual pressure within each said working fluid chamber is biased to a desired pressure within each said working fluid chamber, wherein each said desired pressure is determined by at least a weighted sum of at least one first control parameter corresponding to at least one vehicle attitude difference between at least one actual vehicle attitude detected by a vehicle height detecting means and at least one associated desired vehicle attitude and at least one second control parameter corresponding to the rate of change of said at least one vehicle attitude difference;
wherein said at least one second control parameter is directly proportional to the vehicle speed detected by said vehicle speed detecting means.

3 more elements

Dependencies are inferred from the claim text.