Patent ID: 7975474
Filing Date: 2011-07-12
Classification: F15B,F16H

Abstract:
1. A hydraulic system comprising: a pump for feeding hydraulic fluid from a pump inlet side to a pump outlet side; a pressure accumulator disposed at the pump outlet side; a hydraulic control valve disposed between the pump outlet side and the pressure accumulator, wherein the hydraulic control valve includes at least two valve operating positions; wherein the pump outlet side is connected to the pump inlet side through the control valve in a first valve operating position: wherein the pump outlet side is connected to the pressure accumulator in a second valve operating position and is disconnected from the pressure accumulator in the first valve operating position; wherein the control valve includes a moveable member that determines the valve operating position, which movable member includes two feedback pressure surfaces facing in opposite directions and having respective different hydraulically effective surface areas; wherein a first feedback pressure surface having a smaller hydraulically effective surface area than a larger hydraulically effective surface area of the second feedback pressure surface is acted upon by a biasing force that is a function of the position of the movable member; an orifice plate disposed between the pump outlet and the second feedback pressure surface of the control valve, wherein the orifice plate is positioned between the control valve and the pressure accumulator; wherein the feedback pressure surface having the smaller hydraulically effective surface area is operatively connected to the pressure existing on an upstream side of the orifice plate and the pressure feedback surface having the larger hydraulically effective surface area is operatively connected to the pressure accumulator and is acted upon by the pressure on a downstream side of the orifice plate; and wherein the upstream side of the orifice plate that is connected to the control valve is connected to a tank through a check valve.