Abstract Disclosed is an electromagnetic hydraulic servo valve which receives input signals to control a pilot stage which in turn positions a power valve responsively thereto. The positioning of the power valve controls the flow of fluid under pressure from a source thereof to an actuator which in turn positions the load connected thereto. An intermediate stage of amplification may be inserted between the pilot stage and the power valve if such is desired. A pressure regulator is inserted between the source of fluid under pressure and the input to the pilot stage and/or the intermediate stage of the servo valve. The pressure regulator is responsive only to the load and in accordance therewith has the differential pressure appearing across the actuator applied to the pressure regulator. In response to a static or dynamic load condition a pressure drop directly proportional to the amount of the pressure difference appearing across the actuator is caused to occur in the fluid applied to the input stages (the pilot or intermediate stage). By regulating the pressure applied to the input stage, the velocity of movement of the power valve, and subsequently the acceleration of the actuator ram are controlled. The fluid pressure to the power valve is not subjected to the pressure regulation by the pressure regulator, hence the static performance of the system is maintained.
In an electrohydraulic load positioning system comprising: actuator means, including first and second pressure chambers, for positioning a load; power valve means operatively connected to supply fluid pressure to said pressure chambers of said actuator means; input stage means response to input signals for providing pressure signals to said power valve means; means for connecting a source of fluid under pressure to said input stage means; and a pressure regulator in said connecting means and comprising: a housing defining a cavity having input and output port means; first conduit means for connecting a source of fluid under pressure to said input port means; second conduit means for connecting said output port means to said input stage means; pressure responsive means mounted in said cavity and when in neutral position permitting unimpeded fluid flow from said input to said output port means and movable from said neutral position to impede flow of fluid through said output port means and thereby reduce the pressure applied to said input stage means, said pressure responsive means is a spool valve, said spool valve at least partially blocking said output port means, when moved from said neutral position, to reduce said pressure while maintaining said input port means unimpeded; and third conduit means connecting said first and second chambers of said actuator means to said pressure responsive means, the movement of said pressure responsive means being effected solely by fluid pressure transmitted thereto by said third conduit means, a fluid discharge orifice in said input stage means, said pressure responsive means being the only impediment in the fluid flow path between said source and said discharge orifice in said input stage means.
Claim 2
Dependent Claim
277 words
In an electrohydraulic load positioning system comprising: actuator means, including first and second pressure chambers, for positioning a load; power valve means operatively connected to supply fluid pressure to said pressure chambers of said actuator means; input stage means response to input signals for providing pressure signals to said power valve means; means for connecting a source of fluid under pressure to said input stage means; and a pressure regulator in said connecting means and comprising: a housing defining a cavity having input and output port means; first conduit means for connecting a source of fluid under pressure to said input port means; second conduit means for connecting said output port means to said input stage means; pressure responsive means mounted in said cavity and when in neutral position permitting unimpeded fluid flow from said input to said output port means and movable from said neutral position to impede flow of fluid through said output port means and thereby reduce the pressure applied to said input stage means, said pressure responsive means is a spool valve, said spool valve at least partially blocking said output port means, when moved from said neutral position, to reduce said pressure while maintaining said input port means unimpeded; and third conduit means connecting said first and second chambers of said actuator means to said pressure responsive means, the movement of said pressure responsive means being effected solely by fluid pressure transmitted thereto by said third conduit means, a fluid discharge orifice in said input stage means, said pressure responsive means being the only impediment in the fluid flow path between said source and said discharge orifice in said input stage means.
Claim 3
Dependent Claim
62 words
A load positioning system as defined in claim 1 wherein said output port means includes two openings of equal area defined by said housing and said spool valve includes two lands, one of said lands operating to impede fluid flow through one of said openings and the other of said lands operating to impede fluid flow through the other of said openings.