METHODS AND APPARATUS FOR CONTROLLING PRESSURE AND SUBSTANTIALLY FLOW MATCHED ELECTRO-HYDRAULIC POWER STEERING SYSTEMS

摘要

Methods and apparatus for controlling pressure and substantially flow matched electro-hydraulic power steering systems are disclosed. In particular, the methods include provision of selected values of metering fluid flow to a metering valve (20) adapted for varying pressure values of the metering flow. In a preferred embodiment of the invention, the metering flow is derived from a flow of pressurized fluid which is concomitantly applied to a load valve (64) for driving a load at a pressure substantially equal in value to that attained by the metering flow. In an alternate preferred embodiment of the invention, an independently provided flow of power fluid is controlled equal in pressure value to that attained by the metering flow and utilized by a load valve for driving a load at a pressure substantially equal in value to that attained by the metering flow.