Variable constant force hydraulic components and systems

摘要

An embodiment of the present invention is a valve for selectively establishing communication of a fluid between first and second fluid bodies having first and second pressures, respectively. A valve element is carried within a valve body for linear reciprocal movement along a valve axis between a first position wherein an operative portion at the front of the valve element blocks communication between the first and the second fluid bodies and a second position wherein the first and second fluid bodies are in communication. The movement is responsive to a rearward force exerted by the fluid on the valve element due to the first pressure. The rearward force is less than the product of the first pressure and a cross-sectional area of the first fluid swept by the valve element. An actuator is located at or behind the valve element for applying and modulating forward force to the valve element for controlling the response of the valve element to the first pressure when the valve is located between the first and second positions.