초록 ▼

The hydraulic power steering system comprises a rotary valve unit actuated according to a twisting angle provided in a torsion bar connected between an input shaft and a pinion, and a conversion mechanism which can change the condition of the rotary valve unit for a given twisting angle of the torsi

The hydraulic power steering system comprises a rotary valve unit actuated according to a twisting angle provided in a torsion bar connected between an input shaft and a pinion, and a conversion mechanism which can change the condition of the rotary valve unit for a given twisting angle of the torsion bar. A variable ratio lever mechanism may be used for this purpose. Thus, a torsion bar having a suitable rigidity can be used without causing any insufficiency in the assisting torque because the responsiveness of the steering system can be freely varied by changing the setting of the conversion mechanism. For instance, it is possible to provide a sufficient assist torque at low speed and a controlled responsiveness at high speed.

대표청구항 ▼

A hydraulic power steering system, comprising: a housing; an input shaft rotatably supported by said housing and adapted to be connected to a steering wheel for receiving a steering input; a pinion rotatably supported by said housing and meshing with a steering rack for actuating steerable road whee

A hydraulic power steering system, comprising: a housing; an input shaft rotatably supported by said housing and adapted to be connected to a steering wheel for receiving a steering input; a pinion rotatably supported by said housing and meshing with a steering rack for actuating steerable road wheels; a torsion bar connected between said input shaft and said pinion in a torque transmitting relationship; a power cylinder for actuating said steering rack; a rotary valve unit adapted to be actuated according to a relative angular displacement between said input shaft and said pinion, said rotary valve unit comprising an annular outer valve element fixedly secured to said pinion coaxially with said torsion bar, and an annular inner valve element adjustably and coaxially received in said outer valve element, the relative angular displacement between said inner and outer valve elements determining the allocation of hydraulic pressure from an oil pump to two pressure chambers of said power cylinder; said input shaft, said inner valve element, and said outer valve element being angularly displaceable relative to each other for a given twisting angle of the torsion bar; a conversion mechanism engaged to said input shaft, said inner valve element and said outer valve element for determining relative angular displacements thereof for said given twisting angle of said torsion bar; and varying means for varying said relative angular displacements of said input shaft, said inner valve element and said outer valve element for said given twisting angle of said torsion bar.