Hydraulic valve having pressure compensated demand flow

Claim 2

Directional valve apparatus for controlling the flow of hydraulic fluid under pressure to and from a plurality of loads, comprising: (a) a valve body defining a primary inlet for hydraulic fluid and a primary return outlet; (b) a plurality of control valves for controlling the flow of hydraulic fluid to and from a load, each of said control valves comprising (i) an inlet; (ii) an outlet; (iii) a pair of load ports; (iv) hydraulic fluid circuit means commonly communicating with said load ports; (v) directional valve means variably movable between demand and nondemand positions for selectively delivering variable quantities of hydraulic fluid from the hydraulic fluid circuit means to one of the load ports, and for directing hydraulic fluid from the other port to return; (vi) and flow control valve means comprising pressure responsive means communicating with the associated inlet, outlet and hydraulic fluid circuit means for proportioning hydraulic fluid from the inlet between the hydraulic fluid circuit means and outlet as a function of hydraulic fluid pressure at the associated inlet; hydraulic fluid pressure at said return outlet; hydraulic fluid pressure at the associated load port to which hydraulic fluid is delivered; (vii) said flow control valve means further comprising biasing means for normally urging the flow control means to a position delivering all hydraulic fluid to the hydraulic fluid circuit means; (c) said plurality of control valves being sequentially connected inlet to outlet with the inlet of the first in sequence in communication with said primary inlet, and the outlet of the last in sequence in communication with said primary return outlet; (d) and bypass means including inlet valve means disposed between the primary inlet and primary return outlet for shunting flow directly to return if no directional valve means is in a demand position, and for directing the flow of hydraulic fluid to the inlet of the first control valve in sequence if any directional valve means is in a demand position.

Claim 3

The apparatus defined by claim 1, which further comprises control circuit means operable in conjunction with the respective directional valve means for: (a) communicating return hydraulic fluid pressure to the pressure responsive means of any flow control valve means for which the associated directional valve means is in a nondemand position; or (b) communicating load port pressure to the associated pressure responsive means of any flow control valve means for which the directional valve means is in a demand position; (c) and wherein each flow control valve means is operable to compare hydraulic fluid pressure at the associated inlet with hydraulic fluid pressure at the return outlet or hydraulic fluid pressure at the associated load port, and proportioning hydraulic fluid from the associated inlet between the associated hydraulic fluid circuit means and associated outlet as a function of such comparison.

Claim 4

The apparatus defined by claim 2, wherein the flow of hydraulic fluid proportioned by the flow control valve means to the associated outlet increases as the comparison in favor of inlet pressure increases.

Claim 5

The apparatus defined by claim 2, wherein each of said directional valve means comprises: (a) a spool valve slidably disposed in a cylindrical bore; (b) the associated load ports and hydraulic fluid circuit means being in communication with said bore; (c) the spool valve comprising circumferential grooves and lands for interconnecting the load ports and hydraulic fluid circuit means.

Claim 6

The apparatus defined by claim 4, wherein each spool valve further comprises a plurality of metering grooves formed in one of said lands to permit metered flow between the hydraulic fluid circuit means and the selected load port.

Claim 7

The apparatus defined by claim 4, wherein the control circuit means comprises: (a) a generally axially extending passage formed in the spool valve; (b) and generally radially extending passages communicating with the axial passage and disposed for simultaneous communication with the associated load port to which hydraulic fluid is delivered and the pressure responsive means of the associated flow control valve means.

Claim 8

The apparatus defined by claim 6, and further comprising pressure relief means disposed in said spool valve in communication with said axially extending passage and in communication with said primary return outlet for relieving pressure at the associated load port to which hydraulic fluid is delivered when said pressure reaches a predetermined level.

Claim 9

The apparatus defined by claim 1, wherein each flow control valve means comprises: (a) a spool valve slidably disposed in a cylindrical bore to define closed chambers at each end thereof; (b) the associated inlet, outlet and hydraulic fluid circuit means being in communication with said bore; (c) the spool valve including circumferential grooves and lands for interconnecting the inlet, outlet and hydraulic fluid circuit means; (d) said biasing means comprising a spring disposed in one of said closed chambers; (e) an orifice passage in the spool valve extending between one of said grooves and the other closed chamber to communicate inlet pressure thereto; (f) said control circuit means being in communication with said one closed chamber.

Claim 10

The apparatus defined by claim 8, wherein each spool valve further comprises a plurality of metering grooves formed in one of said lands to permit metered flow between the inlet, outlet and hydraulic fluid circuit means.

Claim 11

The apparatus defined by claim 1, and further comprising normally closed check valve means having an upstream side and downstream side disposed between the primary inlet and the inlet of the first control valve for permitting the flow of hydraulic fluid thereto only if the upstream/downstream pressure differential reaches a predetermined minimum.

Claim 12

The apparatus defined by claim 10, wherein the check valve means comprises a spring biased poppet valve.

Claim 13

The apparatus defined by claim 1, wherein the inlet valve means comprises: (a) normally closed check valve means having an upstream side and downstream side for permitting the flow of hydraulic fluid from the primary inlet to the primary return only if the upstream/downstream pressure differential reaches a predetermined minimum; (b) an orifice passage extending between the upstream and downstream sides of the check valve means; (c) and the bypass means further comprises pilot circuit means extending between the downstream side of the check valve means and said primary return outlet, and operable in conjunction with the respective directional valve means for establishing communication between said downstream side and primary return when all of said directional valve means are in a nondemand position, and for blocking communication therebetween when any of said directional valve means is in a demand position.

Claim 14

The apparatus defined by claim 12, wherein the normally closed check valve means comprises a spring biased poppet valve, and the orifice passage passes through the body of the poppet valve.

Claim 15

The apparatus defined by claim 1, wherein the valve body comprises a plurality of interconnectable and interchangable valve body sections, said primary inlet and primary return outlet in each of said control valves being respectively disposed in separate valve body sections.

Claim 16

Directional valve apparatus for controlling the flow of hydraulic fluid under pressure to and from a plurality of loads, comprising: (a) a valve body defining a primary inlet for hydraulic fluid and a primary return outlet; (b) a plurality of control valves for controlling the flow of hydraulic fluid to and from a load, each of said control valves comprising (i) an inlet; (ii) an outlet; (iii) a pair of load ports; (iv) hydraulic fluid circuit means commonly communicating with said load ports; (v) directional valve means variably movable between demand and nondemand positions for selectively delivering variable quantities of hydraulic fluid from the hydraulic fluid circuit means to one of the load ports, and for directing hydraulic fluid from the other port to return; (iv) and flow control valve means comprising pressure responsive means communicating with the associated inlet, outlet and hydraulic fluid circuit means for proportioning hydraulic fluid from the inlet between the hydraulic fluid circuit means and outlet as a function of hydraulic fluid pressure at the associated inlet; hydraulic fluid pressure at said return outlet; hydraulic fluid pressure at the associated load port to which hydraulic fluid is delivered; (vii) the flow control valve means being movable from a first normal position in which all hydraulic fluid is delivered to the hydraulic circuit means to a second position in which all hydraulic fluid is delivered to the outlet, and including metering means to progressively meter an increasing quantity of hydraulic fluid from the hydraulic circuit means to the outlet as the flow control valve means moves from the first to the second position; (c) said plurality of control valves being sequentially connected inlet to outlet with the inlet of the first in sequence in communication with said primary inlet, and the outlet of the last in sequence in communication with said primary return outlet.

Claim 17

Directional valve apparatus for controlling the flow of hydraulic fluid under pressure to and from a plurality of loads, comprising: (a) a valve body defining a primary inlet for hydraulic fluid and a primary return outlet; (b) a plurality of control valves for controlling the flow of hydraulic fluid to and from a load, each of said control valves comprising (i) an inlet; (ii) an outlet; (iii) a pair of load ports; (iv) hydraulic fluid circuit means commonly communicating with said load ports; (v) directional valve means variably movable between demand and nondemand positions for selectively delivering variable quantities of hydraulic fluid from the hydraulic fluid circuit means to one of the load ports, and for directing hydraulic fluid from the other port to return; (iv) and flow control valve means comprising pressure responsive means communicating with the associated inlet, outlet and hydraulic fluid circuit means for proportioning hydraulic fluid from the inlet between the hydraulic fluid circuit means and outlet as a function of hydraulic fluid pressure at the associated inlet; hydraulic fluid pressure at said return outlet; hydraulic fluid pressure at the associated load port to which hydraulic fluid is delivered; (vii) the flow control valve means being movable from a first normal position in which all hydraulic fluid is delivered to the hydraulic circuit means to a second position in which all hydraulic fluid is delivered to the outlet, and including metering means to progressively meter an increasing quantity of hydraulic fluid from the hydraulic circuit means to the outlet as the flow control valve means moves from the first to the second position; (c) said plurality of control valves being sequentially connected inlet to outlet with the inlet of the first in sequence in communication with said primary inlet, and the outlet of the last in sequence in communication with said primary return outlet.

Claim 18

The apparatus defined by claim 15, wherein each flow control valve means comprises: (a) a spool valve slidably disposed in a cylindrical bore to define closed chambers at each end thereof, said spool valve being movable between said first and second positions; (b) the associated inlet, outlet and hydraulic fluid circuit means being in communication with said bore; (c) the spool valve including circumferential grooves and lands for interconnecting the inlet, outlet and hydraulic fluid circuit means; (d) a biasing spring disposed in one of said closed chambers to normally urge the spool valve to said first position; and (e) an orifice passage in the spool valve extending between one of said grooves and the other closed chamber to communicate inlet pressure thereto; (f) said control circuit means being in communication with said one closed chamber.

Claim 19

The apparatus defined by claim 16, wherein the metering means comprises a plurality of metering grooves formed in one of the lands of said spool valve.

Claim 20

The apparatus defined by claim 15, which further comprises bypass means including inlet valve means disposed between the primary inlet and primary return outlet for shunting flow directly to return if no directional valve means is in a demand position, and for directing the flow of hydraulic fluid to the inlet of the first control valve in sequence if any directional valve means is in a demand position.

Claim 21

Directional valve apparatus for controlling the flow of hydraulic fluid under pressure to and from a plurality of loads, comprising: (a) a valve body defining a primary inlet for hydraulic fluid and a primary return outlet; (b) a plurality of control valves for controlling the flow of hydraulic fluid to and from a load, each of said control valves comprising (i) an inlet; (ii) an outlet; (iii) a pair of load ports; (iv) hydraulic fluid circuit means commonly communicating with said load ports; (v) a spool valve slidably disposed in a cylindrical bore formed within the control valve, the associated load ports and hydraulic fluid circuit means being in communication with said bore, the spool valve comprising circumferential grooves and lands and variably movable between demand and nondemand positions for selectively delivering variable quantities of hydraulic fluid from the hydraulic fluid circuit means to one of the load ports, and for directing hydraulic fluid from the other port to return; (vi) flow control valve means comprising pressure responsive means communicating with the associated inlet, outlet and hydraulic fluid circuit means; (vii) and control circuit means comprising first and second separate axial passage means formed in the spool valve, each constructed and disposed for establishing communication between one of said load ports and the associated flow control means when hydraulic fluid is being delivered to said one load port, the control circuit means being constructed and arranged for communicating return hydraulic fluid pressure to the pressure responsive means of any flow control valve means for which the associated spool valve is in a nondemand position; or communicating load port pressure to the associated pressure responsive means of any flow control valve means for which the spool valve is in a demand position; (viii) each flow control valve means being operable to compare hydraulic fluid pressure at the associated inlet with hydraulic fluid pressure at the return outlet or hydraulic fluid pressure at the associated load port, and proportioning hydraulic fluid from the associated inlet between the associated hydraulic fluid circuit means and associated outlet as a function of such comparison; (c) said plurality of control valves being sequentially connected inlet to outlet with the inlet of the first in sequence in communication with said primary inlet, and the outlet of the last in sequence in communication with said primary return outlet.

Claim 22

Directional valve apparatus for controlling the flow of hydraulic fluid under pressure to and from a plurality of loads, comprising: (a) a valve body defining a primary inlet for hydraulic fluid and a primary return outlet; (b) a plurality of control valves for controlling the flow of hydraulic fluid to and from a load, each of said control valves comprising (i) an inlet; (ii) an outlet; (iii) a pair of load ports; (iv) hydraulic fluid circuit means commonly communicating with said load ports; (v) a spool valve slidably disposed in a cylindrical bore formed within the control valve, the associated load ports and hydraulic fluid circuit means being in communication with said bore, the spool valve comprising circumferential grooves and lands and variably movable between demand and nondemand positions for selectively delivering variable quantities of hydraulic fluid from the hydraulic fluid circuit means to one of the load ports, and for directing hydraulic fluid from the other port to return; (vi) flow control valve means comprising pressure responsive means communicating with the associated inlet, outlet and hydraulic fluid circuit means; (vii) and control circuit means comprising first and second separate axial passage means formed in the spool valve, each constructed and disposed for establishing communication between one of said load ports and the associated flow control means when hydraulic fluid is being delivered to said one load port, the control circuit means being constructed and arranged for communicating return hydraulic fluid pressure to the pressure responsive means of any flow control valve means for which the associated spool valve is in a nondemand position; or communicating load port pressure to the associated pressure responsive means of any flow control valve means for which the spool valve is in a demand position; (viii) each flow control valve means being operable to compare hydraulic fluid pressure at the associated inlet with hydraulic fluid pressure at the return outlet or hydraulic fluid pressure at the associated load port, and proportioning hydraulic fluid from the associated inlet between the associated hydraulic fluid circuit means and associated outlet as a function of such comparison; (c) said plurality of control valves being sequentially connected inlet to outlet with the inlet of the first in sequence in communication with said primary inlet, and the outlet of the last in sequence in communication with said primary return outlet.

Claim 23

The apparatus defined by claim 19, wherein each spool valve further comprises a plurality of metering grooves formed in one of said lands to permit metered flow between the hydraulic fluid circuit means and the selected load port.