FLOW RATE CONTROLLER

PURPOSE:To prevent flow-down and improve the steering assisting force by installing a drain orifice whose opening area is varied according to the displacement of a main spool between a drain passage and the fixed orifice of the captioned device for power steering apparatus for car. CONSTITUTION:The first pressure chamber 36 communicates with a discharge passage 30 through a fixed orifice 31 and a hole 25. A spring 39 is installed in contraction state in the secondary pressure chamber 37, and urges a spool 35 always in the right direction. A drain orifice 42 increases the opening area of a drain passage 29, accompanied with the leftward movement of the spool 35, and an introducing passage 27a and the drain passage 29 communicate with the opening area corresponding to the displacement of the spool 35 through the first pressure chamber 36.