Pressure compensating fluid control valve

Claim 2

A control valve of the type having a body with a valve spool shiftable from a neutral position at which fluid from a fluid inlet passage network flows through the valve to an operating position at which fluid is directed from the fluid inlet passage network to a pressure passage, said pressure passage in the operative position of said valve spool being connected to one of a pair of cylinder passages, the other of said pair of cylinder passages being connected to a tank passage, the valve being characterized by a flow restricting orifice controlled by said valve spool for restricting fluid flow through the valve, valve means for controlling the flow rate between said inlet passage network and said pressure passage, pressure compensating means operatively associated with each end of said valve spool, means for selectively actuating said pressure compensating means for maintaining the flow rate through said valve means to the pressure passage, said compensating means being in fluid communication with said inlet fluid passage network and said pressure passage whereby said valve spool responds to variations in the pressure differential across said valve means to maintain a fixed flow rate through said valve means.

Claim 3

The valve according to claim 1 wherein each of said compensating means comprises a compensating assembly at each end of said valve spool, each assembly having a bore, a ball in said bore, and a spring yieldingly urging each of said balls into engagement with the ends of said valve spool, first passage means providing fluid communication between said inlet passage and said bore on one side of said ball, restricted passage means for providing fluid communication across said bore to both sides of said ball, means for venting the bore to tank on the downstream side of said ball and means for selectively opening one of said venting means whereby fluid under inlet pressure acting on said one side of said ball will tend to move said ball against the bias of said spring allowing said valve spool to move in response to the bias of said spring in the other of said compensating assemblies.

Claim 4

The valve according to claim 2 including second passage means in said valve spool connecting said compensating assemblies to said pressure passage in the neutral position of said valve spool, one of said second passage means being blocked on movement of said valve spool toward an operating position whereby said one of said assemblies is at inlet pressure and the other of said assemblies is substantially at the pressure of the fluid in said pressure passage.

Claim 5

The valve according to claim 3 including means in each of said first passage means for restricting flow whereby said other of said assemblies is maintained substantially at the pressure of said pressure passage.

Claim 6

The valve according to claim 3 including means in each of said second passage means for preventing cylinder pressures higher then inlet pressures from being communicated to either of said compensating assemblies.

Claim 7

The valve according to claim 1 wherein said valve means includes a popPet valve member positioned to control flow between said inlet passage network and said pressure passage, means for biasing said member to a closed position with respect to said inlet passage and means for presetting the operating position of said member.

Claim 8

The valve according to claim 6 wherein said member includes a first cross-sectional area exposed to inlet pressure and a second cross-sectional area exposed to intermediate pressure, said second cross-sectional area being greater than said first cross-sectional area, third passage means through said member providing communication between fluid at inlet pressure and fluid at intermediate pressure, said third passage including a restricted orifice, fourth passage means providing fluid communication between fluid at intermediate pressure and fluid at the pressure of the pressure passage, and means for restricting flow through said fourth passage means.

Claim 9

The valve according to claim 7 wherein said restricting means comprises a valve element operatively positioned for movement into engagement with said valve member to block said fourth passage means and means for selectively moving said valve element a predetermined distance to vary the position of the valve member, whereby the position of said poppet member is stabilized when the force of the fluid at inlet pressure acting on the first area plus the force of the fluid at the pressure of the pressure passage acting on the third surface area equals the force of the fluid at intermediate pressure acting on the second cross-sectional area plus the force of the biasing means.

Claim 10

A pressure compensating flow control valve comprising, a valve body having a bore, a pair of fluid flow recesses in said bore, a fluid inlet passage connected to one of said recesses and a tank passage connected to the other of said recesses, a pair of cylinder passages connected to said bore, a pair of tank passages connected to said bore, a fluid pressure passage connected to said fluid inlet passage and to said bore, a valve spool slidably positioned in said bore for movement in opposite directions from a neutral position wherein the fluid flow recesses are in communication and said cylinder passages and tank passages are closed to an operative position connecting one of said cylinder passages to said pressure passage and the other of said cylinder passages to one of said tank passages, the flow of fluid between said fluid flow recesses being constrained on movement of said valve spool toward the operative position whereby fluid is directed from the fluid inlet passage to flow through said fluid pressure passage, and fluid pressure compensating means at each end of said valve spool to control the position of the valve spool with respect to said fluid flow recesses, each of said compensating means being selectively in fluid communication with said inlet passage and said pressure passage, whereby the flow rate of fluid is maintained at a fixed rate by compensating for any change in the pressure differential between inlet and outlet pressure.

Claim 11

A pressure compensating flow control valve comprising, a valve body having a bore, a pair of fluid flow recesses in said bore, a fluid inlet passage connected to one of said recesses and a tank passage connected to the other of said recesses, a pair of cylinder passages connected to said bore, a pair of tank passages connected to said bore, a fluid pressure passage connected to said fluid inlet passage and to said bore, a valve spool slidably positioned in said bore for movement in opposite directions from a neutral position wherein the fluid flow recesses are in communication and said cylinder passages and tank passages are closed to an operative position connecting one of said cylinder passages to said pressure passage and the other of said cylinder passages to one of said tank passages, the flow of fluid between said fluid flow recesses being constrained on movement of said valve spool toward the operative position whereby fluid is directed from the fluid inlet passage to flow through said fluid pressure passage, and fluid pressure compensating means at each end of said valve spool to control the position of the valve spool with respect to said fluid flow recesses, each of said compensating means being selectively in fluid communication with said inlet passage and said pressure passage, whereby the flow rate of fluid is maintained at a fixed rate by compensating for any change in the pressure differential between inlet and outlet pressure.

Claim 12

The valve according to claim 9 including valve means between said fluid inlet passage and said pressure passage for controlling the flow rate of said fluid from said inlet passage to said pressure passage.

Claim 13

The valve according to claim 9 wherein each of said pressure compensating means includes a housing at each end of said valve body having a cylindrical bore axially aligned with the bore in said body, piston means positioned in said bores, means in said bores for biasing said piston means into engagement with the ends of said valve spool, first passage means connecting each of said bores upstream from said piston means to said inlet passage, and valve means for selectively venting said bores downstream from said piston means whereby said valve spool will move from said neutral position when the force of the inlet fluid pressure acting on said piston means exceeds the bias force of the corrEsponding spring.

Claim 14

The valve according to claim 9 wherein said pressure compensating means includes means for biasing said valve spool to the neutral position and means for applying inlet fluid pressure to one of said biasing means whereby the other of said biasing means will move said spool to the operative position.

Claim 15

The valve according to claim 9 including valve means for selectively varying the flow rate between the inlet passage and the pressure passage.

Claim 16

The valve according to claim 13 wherein said flow rate controlling means includes a poppet valve and means for selectively establishing a predetermined flow rate through said poppet valve.

Claim 17

The valve according to claim 10 wherein said flow rate controlling means includes a poppet valve and a low force proportional solenoid for automatically setting the position of the poppet valve.

Claim 18

The valve according to claim 15 wherein said poppet valve includes a first cross-sectional area surface exposed to inlet fluid pressure, a second cross-sectional area surface exposed to fluid pressure in an intermediate space between said solenoid and said valve, and a third cross-sectional area surface exposed to fluid in said pressure passage, and means for biasing said valve to a closed position with respect to said fluid inlet passage whereby said valve opens when the force of said fluid at inlet pressure acting on said first cross-sectional area is sufficient to overcome the force of said biasing means.

Claim 19

The valve according to claim 16 wherein said poppet valve includes a first restricted flow passage providing fluid communication between said inlet passage and said intermediate space, and a second passage providing fluid communication between said intermediate space and said pressure passage, said solenoid including a pilot valve element positioned to control the flow of fluid through said second passage whereby the flow rate between said inlet fluid passage and said pressure passage is controlled by the flow rate between the intermediate space and said second passage.

Claim 20

The valve according to claim 17 wherein said solenoid includes an armature for supporting said valve element, means for biasing said armature to a closed position with respect to said valve, and means for controlling th force required to move the armature.

Claim 21

A pressure compensated flow control valve comprising a valve body, a bore through said valve body, a fluid inlet passage connected to said bore, a pair of cylinder passages in said body connected to said bore, a proportional force flow control assembly connected to control the fluid flow rate between the fluid inlet passage and said cylinder passage, said assembly including a poppet valve member positioned to provide a flow control orifice between said inlet passage and said cylinder passages, and a low force proportional solenoid operatively connected to control the linear motion of said valve member to establish the size of the control orifice, an exhaust passage connected to said bore, a valve spool slidably positioned in said bore for movement from a neutral position wherein said cylinder passages are closed to an operative position wherein one of said cylinder passages is connected to said fluid inlet passage and the other of said cylinder passages is connected to said exhaust passage, means for biasing said valve spool to a neutral position, and passage means for applying the fluid pressure differential between the pressure of the fluid in the inlet passage and the cylinder passage to said biasing means whereby said valve spool will assume a stable position in the bore in said body when the pressure differential force equals the bias force.

Claim 22

A pressure compensated flow control valve comprising a valve body, a bore through said valve body, a fluid inlet passage connected to said bore, a pair of cylinder passages in said body connected to said bore, a proportional force flow control assembly connected to control the fluid flow rate between the fluid inlet passage and said cylinder passage, said assembly including a poppet valve member positioned to provide a flow control orifice between said inlet passage and said cylinder passages, and a low force proportional solenoid operatively connected to control the linear motion of said valve member to establish the size of the control orifice, an exhaust passage connected to said bore, a valve spool slidably positioned in said bore for movement from a neutral position wherein said cylinder passages are closed to an operative position wherein one of said cylinder passages is connected to said fluid inlet passage and the other of said cylinder passages is connected to said exhaust passage, means for biasing said valve spool to a neutral position, and passage means for applying the fluid pressure differential between the pressure of the fluid in the inlet passage and the cylinder passage to said biasing means whereby said valve spool will assume a stable position in the bore in said body when the pressure differential force equals the bias force.

Claim 23

The control valve according to claim 19 wherein said valve body includes a second bore, a plunger assembly in said second bore, said assembly including a pilot piston to control the flow rate between the inlet passage and the cylinder passage, and a control piston positioned for movement betWeen a neutral position wherein said valve spool is pressure balanced to an operative position wherein said fluid pressure differential applying means is in fluid communication with said inlet passage and said cylinder passage.

Claim 24

A pressure compensated flow control valve comprising: a valve body, a bore through said valve body, a fluid inlet passage connected to said bore, a pressure passage connected to said fluid inlet passage and to said bore on each side of said inlet passage, a pair of cylinder passages in said body connected to said bore at points spaced axially from said pressure passage, a pair of exhaust passages connected to said body at points axially spaced outwardly from said cylinder passages, a valve spool slidably positioned in said bore for movement from a neutral position wherein said fluid from said inlet passage flows through said bore and said cylinder passages are closed to an operative position wherein fluid flow from said inlet passage is restricted to flow through said pressure passage, one of said cylinder passages being connected to said pressure passage and the other of said cylinder passages being connected to said exhaust passages, means for controlling the flow rate of fluid from said inlet passage to said pressure passage, and pressure compensating means for biasing said valve spool to a neutral position, said compensating means being in fluid communication with said inlet passage and said pressure passage wherein the fluid pressure differential between said inlet passage and said pressure passage will determine the position of the valve spool.

Claim 25

A pressure compensated flow control valve comprising: a valve body, a bore through said valve body, a fluid inlet passage connected to said bore, a pressure passage connected to said fluid inlet passage and to said bore on each side of said inlet passage, a pair of cylinder passages in said body connected to said bore at points spaced axially from said pressure passage, a pair of exhaust passages connected to said body at points axially spaced outwardly from said cylinder passages, a valve spool slidably positioned in said bore for movement from a neutral position wherein said fluid from said inlet passage flows through said bore and said cylinder passages are closed to an operative position wherein fluid flow from said inlet passage is restricted to flow through said pressure passage, one of said cylinder passages being connected to said pressure passage and the other of said cylinder passages being connected to said exhaust passages, means for controlling the flow rate of fluid from said inlet passage to said pressure passage, and pressure compensating means for biasing said valve spool to a neutral position, said compensating means being in fluid communication with said inlet passage and said pressure passage wherein the fluid pressure differential between said inlet passage and said pressure passage will determine the position of the valve spool.

Claim 26

The valve according to claim 21 wherein said controlling means includes a poppet valve member positioned to control flow between said inlet passage and said pressure passage, a spring for biasing said member toward the closed position, and means for selectively adjusting the force of said spring.

Claim 27

The valve according to claim 21 wherein said controlling means includes a pilot piston having a pair of valve seats positioned for movement to operative positions with said pressure passage, and a pair of control pistons positioned to control said pressure compensating means.

Claim 28

The valve according to claim 21 wherein said controlling means includes, a poppet valve member, and a low force proportional solenoid assembly for controlling the position of the poppet valve element.

Claim 29

The valve according to claim 24 wherein said solenoid assembly is hydraulically pressure balanced.