SISTEMA DE CONTROLE DE FLUXO AMPLIFICADO E VALVULA DE CONTROLE DIRECIONAL COMPENSADA POR PRESSAO

摘要

Flow amplified control systems are useful in pilot operated steering systems. The load responsive flow amplified control system includes a directional control valve movable to an operating position to direct fluid from the operating fluid circuit through a variable orifice to a steering motor and to direct control fluid from a control fluid circuit through another variable orifice to be combined with the fluid going to the steering motor. The operating fluid circuit and the control fluid circuit are provided with fluid from a common variable displacement pump. The directional control valve is moved to an operating position by the control fluid acting thereon and is pressure compensated insofar as the flow of control fluid passing through the another variable orifice such that a substantially constant predetermined pressure differential exists across the another variable orifice. The rate of fluid flow in the pilot control circuit is determined by a steering control valve and is utilized for controlling the position of the directional control valve. The displacement of the variable displacement pump is responsive to the pressure condition in the pilot control circuit such that a substantially constant predetermined pressure differential exists between the variable displacement pump and the load pressure in the steering motor. The relative size of the variable orifices determines the amplification ratio between the pilot control circuit and the power operating circuit.