Pressure-compensated flow control

Claim 2

A pressure-compensated flow control arrangement for controlling the operation of a fluid motor comprising: a spool valve having a bore, and an inlet passage, a motor passage and a return passage intersecting said bore, and a valve spool movable in said bore to control the fluid connections between said inlet passage and said motor passage and between said motor passage and said return passage, said valve spool having a neutral position blocking said motor passage from both said inlet passage and said return passage, said valve spool being movable from said neutral position to a position connecting said inlet passage to said motor passage and blocking said motor passage from said return passage; a pressure-compensating valve for regulating the inlet flow through said spool valve, said pressure-compensating valve having an inlet port for connection to the source of pressure fluid for the spool valve, a bypass port for bypassing pressure fluid away from said inlet passage of the spool valve, a reference pressure chamber, a pressure-compensating piston disposed between said inlet and bypass ports to control the fluid flow therebetween, said piston having oppositely facing surfaces which are exposed respectively to the fluid pressure at said inlet port and the fluid pressure at said reference pressure chamber, and spring means biasing said piston to a position blocking said bypass port from said inlet port; and connecting passage means including a shuttle valve for connecting said spool valve to said reference pressure chamber of the pressure-compensating valve; said valve spool in its neutral position connecting said return passage to said reference pressure chamber through said connecting passage means; and said valve spool, when displaced from said neutral position to a position connecting said inlet passage to said motor passage, also connecting said motor passage to said reference pressure chamber through said connecting passage means.

Claim 3

A flow control arrangement according to claim 1 wherein said connecting passage means includes an internal longitudinal passage in the valve spool, and transverse port means in the valve spool connecting said internal passage to said bore and registering with said return passage when the valve spool is in its neutral position, said transverse port means registering with said motor passage when the valve spool is displaced to a position connecting said inlet passage to said motor passage and blocking said motor passage from said return passage.

Claim 4

A flow control arrangement according to claim 1, wherein said connecting passage means includes a reference passage intersecting said spool valve bore between said motor passage and said return passage, said valve spool in its neutral position providing fluid communication between said reference passage and said return passage, said valve spool when displaced to said position connecting said inlet passage to said motor passage also providing fluid communication between said motor passage and said reference passage, and said connecting passage means also includes a passage extending from said spool valve reference passage to said reference pressure chamber of the pressure-compensating valve.

Claim 5

A flow control arrangement according to CLAIM 1, wherein said pressure-compensating valve has a controlled flow outlet port connected to said inlet passage of the spool valve, and sad spring means biases said piston to a position blocking said inlet port and said bypass port and said controlled flow outlet port from one another.

Claim 6

A flow control arrangement according to claim 4 wherein said inlet port is disposed between said bypass port and said controlled flow outlet port, and said piston has a pair of axially spaced lands which respectively block said bypass port and said controlled flow outlet passage from said inlet port in said last-mentioned position of the piston.

Claim 7

A pressure-compensated directional flow control arrangement for controlling the operation of a reversible fluid motor comprising: a spool valve having a bore, inlet passage means, a pair of motor passages for connection to the opposite sides of the fluid motor, and return passages intersecting said bore, and a valve spool movable in said bore to control the fluid connections between said inlet passage means and said motor passages and between said motor passages and said return passages, said valve spool having a neutral position blocking both said motor passages from said inlet passage means and from said return passages, said valve spool being movable from said neutral position to a position establishing an inlet flow passage between said inlet passage means and a selected motor passage and establishing a return flow passage between the other motor passage and the corresponding return passage; a pressure-compensating valve for regulating the inlet flow through said spool valve, said pressure-compensating valve having an inlet port for connection to the source of pressure fluid for the spool valve, a bypass port for bypassing pressure fluid away from said inlet passage means of the spool valve, a reference pressure chamber, a piston slidably disposed between said inlet and bypass ports to control the fluid flow therebetween, said piston having oppositely facing surfaces which are exposed respectively to the fluid pressure at said inlet port and the fluid pressure at said reference pressure chamber, and spring means biasing said valve means to a position blocking said bypass port from said inlet port; and a shuttle valve connected between the spool valve and said reference pressure chamber of the pressure-compensating valve and operable, when the valve spool is positioned to establish said inlet and return passages, to connect the motor passage which is in said inlet flow passage to said reference pressure chamber; said valve spool in said neutral position thereof blocking both motor passages from said shuttle valve and connecting the return passages to said reference pressure chamber of the pressure-compensating valve through said shuttle valve.

Claim 8

A pressure-compensated directional flow control arrangement for controlling the operation of a reversible fluid motor comprising: a spool valve having a bore, inlet passage means, a pair of motor passages for connection to the opposite sides of the fluid motor, and return passages intersecting said bore, and a valve spool movable in said bore to control the fluid connections between said inlet passage means and said motor passages and between said motor passages and said return passages, said valve spool having a neutral position blocking both said motor passages from said inlet passage means and from said return passages, said valve spool being movable from said neutral position to a position establishing an inlet flow passage between said inlet passage means and a selected motor passage and establishing a return flow passage between the other motor passage and the corresponding return passage; a pressure-compensating valve for regulating the inlet flow through said spool valve, said pressure-compensating valve having an inlet port for connection to the source of pressure fluid for the spool valve, a bypass port for bypassing pressure fluid away from said inlet passage means of the spool valve, a reference pressure chamber, a piston slidably disposed between said inlet and bypass ports to control the fluid flow therebetween, said piston having oppositely facing surfaces which are exposed respectively to the fluid pressure at said inlet port and the fluid pressure at said reference pressure chamber, and spring means biasing said valve means to a position blocking said bypass port from said inlet port; and a shuttle valve connected between the spool valve and said reference pressure chamber of the pressure-compensating valve and operable, when the valve spool is positioned to establish said inlet and return passages, to connect the motor passage which is in said inlet flow passage to said reference pressure chamber; said valve spool in said neutral position thereof blocking both motor passages from said shuttle valve and connecting the return passages to said reference pressure chamber of the pressure-compensating valve through said shuttle valve.

Claim 9

A flow control arrangement according to claim 6, wherein said shuttle valvE is in the valve spool.

Claim 10

A flow control arrangement according to claim 6, wherein: said valve spool has a pair of longitudinal internal passages therein, and transverse port means connecting said internal passages to the spool valve bore and registrable selectively with said motor passages and return passages in different positions of the valve spool; and said shuttle valve comprises a pair of oppositely facing valve seats connected to the respective internal passages of the valve spool, and a movable valve member reciprocably disposed between said valve seats for sealing engagement with either valve seat while spaced from the other valve seat, and an outlet passage disposed between said valve seats for fluid communication with the valve seat from which the valve member is spaced, said outlet passage being connected to said reference pressure chamber of the pressure-compensating valve.

Claim 11

A flow control arrangement according to claim 8, wherein said transverse port means connect both internal spool passages to said return passages when the valve spool is in said neutral position. 10 A flow control arrangement according to claim 6, wherein: said spool valve has a pair of reference passages intersecting its bore between the motor passages and the respective return passages; said shuttle valve is connected between both said reference passages and the reference pressure chamber of the pressure-compensating valve; said valve spool in its neutral position connects said reference passages to the respective return passages and blocks said reference passages from the respective motor passages; and said valve spool, when positioned to establish said inlet and return flow passages through the spool valve, connects both said reference passages to the respective motor passages.

Claim 12

A pressure-compensated flow control arrangement for controlling the operation of a fluid motor comprising: a flow control valve having inlet and motor ports and a low-pressure return passage, and selectively operable valve means in said control valve controlling the fluid communication between said ports and passages, said valve means having a neutral position blocking said motor port from both said inlet port and said return passage, said valve means being shiftable from said neutral position to a flow-conducting position connecting said inlet port to said motor port and providing a flow restriction between them which varies with the position of said valve means; a pressure-compensating valve connected ahead of the inlet port of said control valve to control the inlet flow thereto; said pressure-compensating valve having one side thereof connected to said motor port and being operable to regulate the inlet flow to the control valve in accordance with the pressure differential across said flow restriction when said valve means in the control valve is in a flow-conducting position; said pressure-compensating valve having one side thereof connected to said return passage when said valve means in the flow control valve is in said neutral position; and a shuttle valve interposed said one side of said pressure-compensating valve and said flow control valve.

Claim 13

A pressure-compensated flow control arrangement for controlling the operation of a fluid motor comprising: a flow control valve having inlet and motor ports and a low-pressure return passage, and selectively operable valve means in said control valve controlling the fluid communication between said ports and passages, said valve means having a neutral position blocking said motor port from both said inlet port and said return passage, said valve means being shiftable from said neutral position to a flow-conducting position connecting said inlet port to said motor port and providing a flow restriction between them which varies with the position of said valve means; a pressure-compensating valve connected ahead of the inlet port of said control valve to control the inlet flow thereto; said pressure-compensating valve having one side thereof connected to said motor port and being operable to regulate the inlet flow to the control valve in accordance with the pressure differential across said flow restriction when said valve means in the control valve is in a flow-conducting position; said pressure-compensating valve having one side thereof connected to said return passage when said valve means in the flow control valve is in said neutral position; and a shuttle valve interposed said one side of said pressure-compensating valve and said flow control valve.

Claim 14

A pressure-compensated directional flow control arrangement for controlling the operation of a reversible fluid motor comprising: a spool valve having a bore, inlet passage means, a pair of motor passages and a pair of return passages intersecting said bore, and a valve spool movable in said bore to control the fluid connections between said inlet passage means and said motor passages and between said motor passages and said return passages; said valve spool having a pair of longitudinal internal passages spaced apart axially of the spool therein and transverse port means connecting said internal passages to the spool valve bore, and a shuttle valve in the spool operatively connected between said internal passages and exposed to the fluid pressure in each, said shuttle valve compRising a pair of oppositely facing valve seats connected individually to the respective internal passages of the spool, a movable valve member reciprocably disposed between said valve seats for sealing engagement with either valve seat while spaced from the other valve seat, and an outlet passage disposed between said valve seats for fluid communication with the valve seat from which the valve member is spaced, said transverse port means connecting both internal passages of the valve spool to said return passages when the valve spool is in a neutral position blocking said inlet passage means from said motor passages, said valve spool means being shiftable longitudinally to connect said inlet passage means to a selected one of said motor passages and to connect the other of said motor passages to a return passage and to connect the motor passages to the respective internal passages in the valve spool through said transverse port means therein; a pressure-compensating valve for regulating the inlet flow through said spool valve, said pressure-compensating valve having an inlet port for connection to the source of pressure fluid for the spool valve, a bypass port for bypassing pressure fluid away from said inlet passage means of the spool valve, a reference pressure chamber, a piston slidably disposed between said inlet and bypass port to control the fluid flow therebetween, said piston having oppositely facing surfaces which are exposed respectively to the fluid pressure at said inlet port and the fluid pressure at said reference pressure chamber, spring means biasing said valve means to a position blocking said bypass port from said inlet port, and passage means connecting said reference pressure chamber to said shuttle valve in the spool to apply to said reference pressure chamber the fluid pressure in the longitudinal internal passage which is in communication with the valve seat which is spaced from said valve member.

Claim 15

A pressure-compensated directional flow control arrangement for controlling the operation of a reversible fluid motor comprising: a spool valve having a bore, inlet passage means, a pair of motor passages and a pair of return passages intersecting said bore, and a valve spool movable in said bore to control the fluid connections between said inlet passage means and said motor passages and between said motor passages and said return passages; said valve spool having a pair of longitudinal internal passages spaced apart axially of the spool therein and transverse port means connecting said internal passages to the spool valve bore, and a shuttle valve in the spool operatively connected between said internal passages and exposed to the fluid pressure in each, said shuttle valve compRising a pair of oppositely facing valve seats connected individually to the respective internal passages of the spool, a movable valve member reciprocably disposed between said valve seats for sealing engagement with either valve seat while spaced from the other valve seat, and an outlet passage disposed between said valve seats for fluid communication with the valve seat from which the valve member is spaced, said transverse port means connecting both internal passages of the valve spool to said return passages when the valve spool is in a neutral position blocking said inlet passage means from said motor passages, said valve spool means being shiftable longitudinally to connect said inlet passage means to a selected one of said motor passages and to connect the other of said motor passages to a return passage and to connect the motor passages to the respective internal passages in the valve spool through said transverse port means therein; a pressure-compensating valve for regulating the inlet flow through said spool valve, said pressure-compensating valve having an inlet port for connection to the source of pressure fluid for the spool valve, a bypass port for bypassing pressure fluid away from said inlet passage means of the spool valve, a reference pressure chamber, a piston slidably disposed between said inlet and bypass port to control the fluid flow therebetween, said piston having oppositely facing surfaces which are exposed respectively to the fluid pressure at said inlet port and the fluid pressure at said reference pressure chamber, spring means biasing said valve means to a position blocking said bypass port from said inlet port, and passage means connecting said reference pressure chamber to said shuttle valve in the spool to apply to said reference pressure chamber the fluid pressure in the longitudinal internal passage which is in communication with the valve seat which is spaced from said valve member.