| 摘要 |
A controller for fluid pressure operated devices such as power steering systems. The controller is of the type having a primary, rotatable valve member and a follow-up valve member, the valve members defining a neutral position. The follow-up valve member is coupled to the primary valve member for limited movement relative to the neutral position. The controller further comprises a fluid meter including a metering member for measuring the volume of fluid passing therethrough, the metering member being coupled to the follow-up valve member. The controller has an inlet port and first and second control fluid ports which may be connected to the opposite ends of the power steering cylinder. The primary and follow-up valve members cooperate with the housing to define a first plurality of fluid passages providing fluid communication between the inlet port and the first control fluid port through the fluid meter when the valve members are relatively displaced in one direction from the neutral position and providing fluid communicating between the inlet port and the second control fluid port through the meter when the valve members are relatively displaced in the other direction from the neutral position. The first and second pluralities of fluid passages provide substantially the same length of fluid flow path between the inlet port and the corresponding control fluid ports in either direction of displacement of the valve member from the neutral position to provide uniform response in either direction. Preferably, the first and second pluralities of fluid passages are arranged in substantially a mirror image of each other with respect to an imaginary plane perpendicular to the axes of rotation of the valve members, to minimize steering wheel precession. In addition, the valve members maintain axial separation of the fluid flowing to a control fluid port and the fluid returning from a control fluid port to minimize internal leakage.
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