Patent ID: 6520278
Filing Date: 2003-02-18
Classification: B62D

Abstract:
A hydraulic power steering apparatus comprising:a hydraulic pump, a reservoir tank, an oil passage selector valve, which selects between a right and or a left hydraulic flow path a power cylinder having right and left oil chambers, and a damper valve composed of a spool valve having a single spool valve body, a control oil chamber, a back pressure chamber with a bias spring, and right and left oil passages; said reservoir tank hydraulically interconnected between said oil passage selector valve, said spool valve back pressure chamber and an inlet of said hydraulic pump; said hydraulic pump having an outlet hydraulically interconnected with said damper valve control oil chamber and said oil passage selector valve; said damper valve right and left oil passages hydraulically interconnected between said oil passage selector valve right and left hydraulic flow paths and said power cylinder right and left oil chambers by left and right connecting oil passages; said spool valve operates upon said connecting right and left oil passages, opening or closing said connecting right and left oil passages at the same time; whereby when a discharge oil pressure of said hydraulic pump decreases, a pressure in said control oil chamber decreases allowing said bias spring to move said spool valve to a position restricting said connecting right and left oil passages.