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This paper reports a development of a balanced vane pump which utilizes a cam ring and plates with the most suitable configuration to drastically reduce its flow ripple output which is converted into pressure pulsation and finally acoustic noise. This pump, developed for vehicles with power steering mechanisms through computer simulation technology, is a low-pulsation pump with a small number of vanes, which has been difficult to construct for noise problems. The theoretical basis for the technique is presented, along with an example of pump design using a vane-raising speed control.

A new variable displacement pump has been developed. This pump can variably change its discharged flow rate in accordance with the revolution changes of an automotive engine from idling engine speed to 6000rpm. It can quickly discharge oil necessary for controlling the autmotive active suspension system. This pump is of a swash plate, axial piston type which controls optimal fluid flow in time by using a pressure sensing control valve. Further, in order to improve the quietness in the vehicle system, the pulsation of the pump pressure was reduced and this pump's utility was realized for automobile use. This is a report on how the pump was introduced for commercial automobile use.

The adaptation of the active control technology to practical suspension systems of vehicles has remarkably improved the safety and ride-comfort of vehicles. This paper presents a study on the practical realization methods of an active suspension system that combines high response and low energy dissipation. The effects of active control on the stability of vehicle motion and ride-comfort were investigated by practical tests using an experimental vehicle. The integrated active suspension system consists of a motor-controlled oil pump, which is active power source, and a motor-controlled variable orifice, which is semi-active adjustable element. Multi-controller computer systems for individual controls of each suspension unit and an integrated control of the whole body behavior are also installed.

An active suspension system controls a spring constant and an attenuater in real time using a power supply. Generally, the hydraulic pressures are used for transmitting the power. Therefore, a highly reliable and inexpensive control system has been required for a commercial use. This has been achieved by developing a mechanical fluid servo valve which comprises a simple combination of a solenoid valve and a spool valve. The technical problem of the valve vibrations has been solved through the numerical analyses, the fluid flow visualization tests and the vehicle tests.