Load responsive fluid control valve

Claim 2

A valve assembly comprising a housing having an inlet chamber connected to a fluid motor, and an exhaust chamber connected to exhaust means, control orifice means interposed between said inlet chamber and said fluid motor, first valve means having fluid throttling means between said inlet chamber and said exhaust chamber controllable by a pilot valve means and operable to throttle fluid flow from said inlet chamber to said exhaust chamber to maintain a constant pressure differential at a preselected constant level across said pilot valve means and to maintain a constant pressure differential across said control orifice means, and second valve means having means operable through said first valve means to vary the level of said constant pressure differential across said control orifice means while said pressure differential across said pilot valve means remains constant at said constant predetermined level.

Claim 3

A valve assembly as set forth in claim 1 wherein said control orifice means has variable area orifice means.

Claim 4

A valve assembly as set forth in claim 1 wherein said second valve means has means to vary the level of said constant pressure differential across said control orifice means above the level of said pressure differential across said pilot valve means maintained constant at said constant predetermined level.

Claim 5

A valve assembly as set forth in claim 1 wherein said second valve means includes constant pressure reducing means, orifice means upstream of said constant pressure reducing means, and flow orifice means down stream of said constant pressure reducing means.

Claim 6

A valve assembly as set forth in claim 1 wherein said second valve means includes fluid throttling means and orifice means down stream of said fluid throttling means communicable with said exhaust means.

Claim 7

A valve assembly as set forth in claim 1 wherein said second valve means has means to vary the level of said constant pressure differential across said control orifice means below the level of said pressure differential across said pilot valve means maintained constant at said constant predetermined level.

Claim 8

A valve assembly as set forth in claim 1 wherein said second valve means has means responsive to an external control signal.

Claim 9

A valve assembly as set forth in claim 7 wherein said means responsive to an external control signal includes mechanical actuating means.

Claim 10

A valve assembly as set forth in claim 7 wherein said means responsive to an external control signal includes fluid pressure actuating means.

Claim 11

A valve assembly as set forth in claim 7 wherein said means responsive to an external control signal includes electro-hydraulic actuating means.

Claim 12

A valve assembly as set forth in claim 7 wherein said means responsive to an external control signal includes electro-mechanical actuating means.

Claim 13

A valve assembly comprising a housing having an inlet chamber connected to a fluid motor, and an exhaust chamber connected to exhaust means, control orifice means interposed between said fluid motor and said inlet chamber, first and second control chambers in said housing, first valve means having fluid throttling means between said inlet chamber and said exhaust chamber responsive to pressure in said first control chamber, and pilot valve means operable to control pressure in said first control chamber having means responsive to pressure in said second control chamber and to pressure in said fluid motor, said first valve means operable to throttle fluid flow from said inlet chamber to said exhaust chamber to maintain a constant pressure differential at a preselected constant level between said fluid motor and said second control chamber and across said pilot valve means and to maintain a constant pressure differential across said control orifice means, pressure signal transmitting means operable to transmit control pressure signal from down stream of said control orifice means to said second control chamber, and modifying means of said control pressure signal operable through said first valve means to vary the level of said constant pressure differential controlled across said control orifice means while said pressure differential across said pilot valve means remains constant at said constant predetermined level.

Claim 14

A valve assembly comprising a housing having an inlet chamber connected to a fluid motor, and an exhaust chamber connected to exhaust means, control orifice means interposed between said fluid motor and said inlet chamber, first and second control chambers in said housing, first valve means having fluid throttling means between said inlet chamber and said exhaust chamber responsive to pressure in said first control chamber, and pilot valve means operable to control pressure in said first control chamber having means responsive to pressure in said second control chamber and to pressure in said fluid motor, said first valve means operable to throttle fluid flow from said inlet chamber to said exhaust chamber to maintain a constant pressure differential at a preselected constant level between said fluid motor and said second control chamber and across said pilot valve means and to maintain a constant pressure differential across said control orifice means, pressure signal transmitting means operable to transmit control pressure signal from down stream of said control orifice means to said second control chamber, and modifying means of said control pressure signal operable through said first valve means to vary the level of said constant pressure differential controlled across said control orifice means while said pressure differential across said pilot valve means remains constant at said constant predetermined level.

Claim 15

A valve assembly as set forth in claim 12 wherein said modifying means of said control pressure signal has means to vary the level of said constant pressure differential across said control orifice means below the level of said pressure differential between said fluid motor and said second control chamber maintained constant at said constant predetermined level.

Claim 16

A valve assembly as set forth in claim 12 wherein said modifying means of said control pressure signal includes constant pressure reducing means, orifice means upstream of said constant pressure reducing means, and flow orifice means down stream of said constant pressure reducing means.

Claim 17

A valve assembly as set forth in claim 12 wherein said modifying means of said control pressure signal includes fluid throttling means and orifice means down stream of said fluid throttling means communicable with said exhaust means.

Claim 18

A valve assembly as set forth in claim 12 wherein said modifying means of said control pressure signal has means responsive to an external control signal.

Claim 19

A valve assembly comprising a housing having an inlet chamber connected to a fluid motor, and an exhaust chamber connected to exhaust means, control orifice means interposed between said fluid motor and said inlet chamber, first, second and third control chambers in said housing, first valve means having fluid throttling means between said inlet chamber and said exhaust chamber responsive to pressure in said first control chamber and pilot valve means operable to control pressure in said first control chamber having means responsive to pressure in said second control chamber and to pressure in said third control chamber, said first valve means operable to throttle fluid flow from said inlet chamber to said exhaust chamber to maintain a constant pressure differential at a preselected constant level between said third control chamber and said second control chamber and across said pilot valve means and to maintain a constant pressure differential across said control orifice means, passage means interconnecting said second control chamber and said inlet chamber, pressure signal transmitting means operable to transmit control pressure signal from said fluid motor to said third control chamber, and modifying means of said control pressure signal operable through said first valve means to vary the level of said constant pressure differential controlled across said control orifice means while said pressure differential across said pilot valve means remains constant at said constant predetermined level.

Claim 20

A valve assembly comprising a housing having an inlet chamber connected to a fluid motor, and an exhaust chamber connected to exhaust means, control orifice means interposed between said fluid motor and said inlet chamber, first, second and third control chambers in said housing, first valve means having fluid throttling means between said inlet chamber and said exhaust chamber responsive to pressure in said first control chamber and pilot valve means operable to control pressure in said first control chamber having means responsive to pressure in said second control chamber and to pressure in said third control chamber, said first valve means operable to throttle fluid flow from said inlet chamber to said exhaust chamber to maintain a constant pressure differential at a preselected constant level between said third control chamber and said second control chamber and across said pilot valve means and to maintain a constant pressure differential across said control orifice means, passage means interconnecting said second control chamber and said inlet chamber, pressure signal transmitting means operable to transmit control pressure signal from said fluid motor to said third control chamber, and modifying means of said control pressure signal operable through said first valve means to vary the level of said constant pressure differential controlled across said control orifice means while said pressure differential across said pilot valve means remains constant at said constant predetermined level.

Claim 21

A valve assembly as set forth in claim 17 wherein said modifying means of said control pressure signal has means to vary the level of said constant pressure differential across said control orifice means above the level of said pressure differential between said third and said second control chambers maintained constant at said constant predetermined level.

Claim 22

A valve assembly as set forth in claim 17 wherein said modifying means of said control pressure signal includes constant pressure reducing means, orifice means upstream of said constant pressure reducing means, and flow orifice means down stream of said constant pressure reducing means.

Claim 23

A valve assembly as set forth in claim 17 wherein said modifying means of said control pressure signal includes fluid throttling means and orifice means down stream of said fluid throttling means communicable with said exhaust means.

Claim 24

A valve assembly as set forth in claim 17 wherein said modifying means of said control pressure signal has means responsive to an external control signal.

Claim 25

A valve assembly comprising a housing having a fluid inlet chamber connected to a pump, at least one load chamber, a fluid exhaust chamber, and exhaust means, first valve means for selectively interconnecting said load chamber with said inlet chamber and said exhaust chamber, variable orifice means between said load chamber and said exhaust chamber operable by said first valve means, load pressure sensing means selectively communicable with said load chamber by said first valve means, first and second control chambers in said housing, second valve means having fluid throttling means between said exhaust chamber and said exhaust means responsive to pressure in said first control chamber and pilot valve means operable to control pressure in said first control chamber having means responsive to pressure in said second control chamber and means responsive to pressure in said load pressure sensing means, said first valve means operable to throttle fluid flow from said exhaust chamber to said exhaust means to maintain a constant pressure differential at a preselected constant level between said load chamber and said second control chamber and across said pilot valve means and to maintain a constant pressure differential across said variable orifice means, pressure signal transmitting means operable to transmit control pressure signal from said exhaust chamber to said second control chamber, and modifying means of said control pressure signal operable through said second valve means to vary the level of said constant pressure differential controlled across said variable orifice means, while said pressure differential between said load chamber and said second control chamber and across said pilot valve means remains constant at said constant predetermined level.

Claim 26

A valve assembly comprising a housing having a fluid inlet chamber connected to a pump, at least one load chamber, a fluid exhaust chamber, and exhaust means, first valve means for selectively interconnecting said load chamber with said inlet chamber and said exhaust chamber, variable orifice means between said load chamber and said exhaust chamber operable by said first valve means, load pressure sensing means selectively communicable with said load chamber by said first valve means, first and second control chambers in said housing, second valve means having fluid throttling means between said exhaust chamber and said exhaust means responsive to pressure in said first control chamber and pilot valve means operable to control pressure in said first control chamber having means responsive to pressure in said second control chamber and means responsive to pressure in said load pressure sensing means, said first valve means operable to throttle fluid flow from said exhaust chamber to said exhaust means to maintain a constant pressure differential at a preselected constant level between said load chamber and said second control chamber and across said pilot valve means and to maintain a constant pressure differential across said variable orifice means, pressure signal transmitting means operable to transmit control pressure signal from said exhaust chamber to said second control chamber, and modifying means of said control pressure signal operable through said second valve means to vary the level of said constant pressure differential controlled across said variable orifice means, while said pressure differential between said load chamber and said second control chamber and across said pilot valve means remains constant at said constant predetermined level.

Claim 27

A valve assembly as set forth in claim 22 wherein said first valve means has a neutral position in which it blocks said load pressure sensing means, said first valve means when displaced from said neutral position first connecting said load pressure sensing means with said load chamber before connecting said load chamber with said exhaust chamber.

Claim 28

A valve assembly comprising a housing having a load chamber connected to a fluid motor, an exhaust chamber connected to exhaust means, and load pressure sensing port means, first valve means for selectively interconnecting said load chamber with said exhaust chamber and said load sensing port means, said first valve means having a variable orifice means between said load chamber and said exhaust chamber, second valve means communicable with said load pressure sensing port means having fluid throttling means between said exhaust chamber and said exhaust means controllable by a pilot valve means and operable to throttle fluid flow from said exhaust chamber to said exhaust means to maintain a constant pressure differential at a preselected constant level across said pilot valve means and to maintain a constant pressure differential across said variable orifice means, and third valve means having means operable through said second valve means to vary the level of said constant pressure differential across said variable orifice means while said pressure differential across said pilot valve means remains constant at said constant predetermined level.

Claim 29

A valve assembly comprising a housing having a load chamber connected to a fluid motor, an exhaust chamber connected to exhaust means, and load pressure sensing port means, first valve means for selectively interconnecting said load chamber with said exhaust chamber and said load sensing port means, said first valve means having a variable orifice means between said load chamber and said exhaust chamber, second valve means communicable with said load pressure sensing port means having fluid throttling means between said exhaust chamber and said exhaust means controllable by a pilot valve means and operable to throttle fluid flow from said exhaust chamber to said exhaust means to maintain a constant pressure differential at a preselected constant level across said pilot valve means and to maintain a constant pressure differential across said variable orifice means, and third valve means having means operable through said second valve means to vary the level of said constant pressure differential across said variable orifice means while said pressure differential across said pilot valve means remains constant at said constant predetermined level.

Claim 30

A valve assembly as set forth in claim 24 wherein said third valve means has means responsive to an external control signal.

Claim 31

A valve assembly as set forth in claim 25 wherein said means responsive to an external control signal includes mechanical actuating means.

Claim 32

A valve assembly as set forth in claim 25 wherein said means responsive to an external control signal includes fluid pressure actuating means.

Claim 33

A valve assembly as set forth in claim 25 wherein said means responsive to an external control signal includes electro-hydraulic actuating means.

Claim 34

A valve assembly as set forth in claim 25 wherein said means responsive to an external control signal includes electro-mechanical actuating means.

Claim 35

A load responsive valve assembly comprising a housing having an inlet chamber connected to a fluid motor, and an exhaust chamber connected to exhaust means, control orifice means interposed between said inlet chamber and said fluid motor, first valve means having fluid throttling means between said inlet chamber and said exhaust chamber controllable by a pilot valve means and operable to throttle fluid flow from said inlet chamber to said exhaust chamber to maintain a constant pressure differential at a preselected constant level across said pilot valve means and to maintain a constant pressure differential across said control orifice means.

Claim 36

A load responsive valve assembly comprising a housing having an inlet chamber connected to a fluid motor, and an exhaust chamber connected to exhaust means, control orifice means interposed between said inlet chamber and said fluid motor, first valve means having fluid throttling means between said inlet chamber and said exhaust chamber controllable by a pilot valve means and operable to throttle fluid flow from said inlet chamber to said exhaust chamber to maintain a constant pressure differential at a preselected constant level across said pilot valve means and to maintain a constant pressure differential across said control orifice means.

Claim 37

A load responsive valve assembly as set forth in claim 30 wherein said pilot valve means has means responsive to pressure in said fluid motor.

Claim 38

A load responsive valve assembly as set forth in claim 30 wherein said control orifice means has variable area orifice means.

Claim 39

A load responsive valve assembly comprising a housing having an inlet chamber connected to a fluid motor, and an exhaust chamber connected to exhaust means, control orifice means interposed between said inlet chamber and said fluid motor, first and second control chambers in said housing, first valve means having fluid throttling means between said inlet chamber and said exhaust chamber provided with means responsive to pressure in said first control chamber, and pilot valve means operable to control pressure in said first control chamber having means responsive to pressure in said second control chamber and to pressure in said fluid motor, said first valve means operable to throttle fluid flow from said inlet chamber to said exhaust chamber to maintain a constant pressure differential at a preselected constant level between said fluid motor and said second control chamber and across said pilot valve means and to maintain a constant pressure differential across said control orifice means.

Claim 40

A load responsive valve assembly comprising a housing having an inlet chamber connected to a fluid motor, and an exhaust chamber connected to exhaust means, control orifice means interposed between said inlet chamber and said fluid motor, first and second control chambers in said housing, first valve means having fluid throttling means between said inlet chamber and said exhaust chamber provided with means responsive to pressure in said first control chamber, and pilot valve means operable to control pressure in said first control chamber having means responsive to pressure in said second control chamber and to pressure in said fluid motor, said first valve means operable to throttle fluid flow from said inlet chamber to said exhaust chamber to maintain a constant pressure differential at a preselected constant level between said fluid motor and said second control chamber and across said pilot valve means and to maintain a constant pressure differential across said control orifice means.

Claim 41

A load responsive valve assembly as set forth in claim 33 wherein said second control chamber is connected with pressure conducting means with down stream of said control orifice means.

Claim 42

A load responsive valve assembly as set forth in claim 33 wherein said fluid throttling means has spring biasing means opposing the force developed by said means responsive to pressure in said first control chamber.

Claim 43

A load responsive valve assembly comprising a housing having an inlet chamber connected to a fluid motor, and an exhaust chamber connected to exhaust means, control orifice means interposed between said fluid motor and said inlet chamber, first, second and third control chambers in said housing, first valve means having fluid throttling means between said inlet chamber and said exhaust chamber provided with means responsive to pressure in said first control chamber, and pilot valve means operable to control pressure in said first control chamber having means responsive to pressure in said second control chamber and said third control chamber, said first valve means operable to throttle fluid flow from said inlet chamber to said exhaust chamber to maintain a constant pressure differential at a preselected constant level between said third and said second control chambers and across said pilot valve means and to maintain a constant pressure differential across said control orifice means.

Claim 44

A load responsive valve assembly comprising a housing having an inlet chamber connected to a fluid motor, and an exhaust chamber connected to exhaust means, control orifice means interposed between said fluid motor and said inlet chamber, first, second and third control chambers in said housing, first valve means having fluid throttling means between said inlet chamber and said exhaust chamber provided with means responsive to pressure in said first control chamber, and pilot valve means operable to control pressure in said first control chamber having means responsive to pressure in said second control chamber and said third control chamber, said first valve means operable to throttle fluid flow from said inlet chamber to said exhaust chamber to maintain a constant pressure differential at a preselected constant level between said third and said second control chambers and across said pilot valve means and to maintain a constant pressure differential across said control orifice means.

Claim 45

A load responsive valve assembly as set forth in claim 36 wherein said second control chamber is connected by first pressure conducting means with upstream of said control orifice means.

Claim 46

A load responsive valve assembly as set forth in claim 36 wherein said third control chamber is connected by second pressure conducting means with down stream of said control orifice means.

Claim 47

A load responsive valve assembly as set forth in claim 36 wherein said fluid throttling means has spring biasing means opposing the force developed by said means responsive to pressure in said first control chamber.

Claim 48

A load responsive valve assembly comprising a housing having a fluid inlet chamber, at least one load chamber, and an exhaust chamber, first valve means for selectively interconnecting said load chamber with said inlet chamber and said exhaust chamber, variable orifice means between said load chamber and said exhaust chamber operable by said first valve means, load pressure sensing means selectively communicable with said load chamber by said first valve means, and fluid throttling means interposed between said exhaust chamber and exhaust means, control signal transmitting means having means to transmit a first pressure signal from said exhaust chamber and means to transmit a second pressure signal from said load pressure sensing means, control means of said fluid throttling means having pilot valve means communicable with said first and said second pressure signals and operable through said fluid throttling means to throttle fluid flow from said exhaust chamber to said exhaust means to maintain a relatively constant pressure differential at a constant predetermined level across said pilot valve means and to maintain a constant pressure differential across said variable orifice means.

Claim 49

A load responsive valve assembly comprising a housing having a fluid inlet chamber, at least one load chamber, and an exhaust chamber, first valve means for selectively interconnecting said load chamber with said inlet chamber and said exhaust chamber, variable orifice means between said load chamber and said exhaust chamber operable by said first valve means, load pressure sensing means selectively communicable with said load chamber by said first valve means, and fluid throttling means interposed between said exhaust chamber and exhaust means, control signal transmitting means having means to transmit a first pressure signal from said exhaust chamber and means to transmit a second pressure signal from said load pressure sensing means, control means of said fluid throttling means having pilot valve means communicable with said first and said second pressure signals and operable through said fluid throttling means to throttle fluid flow from said exhaust chamber to said exhaust means to maintain a relatively constant pressure differential at a constant predetermined level across said pilot valve means and to maintain a constant pressure differential across said variable orifice means.

Claim 50

A load responsive valve assembly as set forth in claim 40 wherein said first valve means has a neutral position and isolating means operable to isolate in said neutral position said load pressure sensing means from said load chamber.

Claim 51

A load responsive valve assembly comprising a housing having a fluid inlet chamber connected to a pump, a load chamber connected to a fluid motor, an exhaust chamber, and load pressure sensing port means, first valve means for selectively interconnecting said load chamber with said inlet chamber, exhaust means and said load pressure sensing port means, said first valve means having a variable orifice means between said load chamber and said exhaust chamber, second valve means communicable with said load pressure sensing port means having fluid throttling means between said exhaust chamber and said exhaust means controllable by a pilot valve means and operable to throttle fluid flow from said fluid motor to said exhaust means to maintain a constant pressure differential at a preselected constant level across said pilot valve means and to maintain a constant pressure differential across said variable orifice means.

Claim 52

A load responsive valve assembly comprising a housing having a fluid inlet chamber connected to a pump, a load chamber connected to a fluid motor, an exhaust chamber, and load pressure sensing port means, first valve means for selectively interconnecting said load chamber with said inlet chamber, exhaust means and said load pressure sensing port means, said first valve means having a variable orifice means between said load chamber and said exhaust chamber, second valve means communicable with said load pressure sensing port means having fluid throttling means between said exhaust chamber and said exhaust means controllable by a pilot valve means and operable to throttle fluid flow from said fluid motor to said exhaust means to maintain a constant pressure differential at a preselected constant level across said pilot valve means and to maintain a constant pressure differential across said variable orifice means.

Claim 53

A load responsive valve assembly as set forth in claim 42 wherein said pilot valve means has first means responsive to pressure upstream of said variable orifice means and second means responsive to pressure down stream of said variable orifice means.