Hydraulic system and valve therefor

Claim 2

A hydraulic system comprising: a plurality of pumps, each having a pressure side and an intake side; conduit means defining two distinct circulating paths including a respective circulating path for each of said pumps, eAch said conduit means including respective ducts connected to said pressure side and said intake side of each pump; two independently operable control valves including a respective control valve connecting each of said paths with a respective hydraulically operable load; a selectively shiftable auxiliary valve in at least one of said paths permitting circulation of a hydraulic medium therealong but actuatable to block such circulation, said auxiliary valve having a first position communicating between said duct connected to said pressure side and said duct connected to the intake side of the respective pump and permitting return flow of fluid from the respective path to the respective pump and a second position blocking return flow of fluid: a shunt conduit connecting said one of said paths, between said auxiliary valve and the pump associated with said one of said paths at the duct connected to the pressure side of the latter pump, with another of said paths; and an automatically operable check valve in said shunt conduit automatically opening upon shifting of said auxiliary valve into said second position for undirectional flow of the medium between said one of said paths and said other of said paths upon blockage of circulation in said one path by said auxiliary valve and upon the fluid pressure at said shunt conduit exceeding the fluid pressure at said other path whereby a load energized through the control valve of said other path may draw upon medium from both said one of said paths and said other path.

Claim 3

A hydraulic system comprising: a plurality of pumps, each having a pressure side and an intake side; conduit means defining two distinct circulating paths including a respective circulating path for each of said pumps, eAch said conduit means including respective ducts connected to said pressure side and said intake side of each pump; two independently operable control valves including a respective control valve connecting each of said paths with a respective hydraulically operable load; a selectively shiftable auxiliary valve in at least one of said paths permitting circulation of a hydraulic medium therealong but actuatable to block such circulation, said auxiliary valve having a first position communicating between said duct connected to said pressure side and said duct connected to the intake side of the respective pump and permitting return flow of fluid from the respective path to the respective pump and a second position blocking return flow of fluid: a shunt conduit connecting said one of said paths, between said auxiliary valve and the pump associated with said one of said paths at the duct connected to the pressure side of the latter pump, with another of said paths; and an automatically operable check valve in said shunt conduit automatically opening upon shifting of said auxiliary valve into said second position for undirectional flow of the medium between said one of said paths and said other of said paths upon blockage of circulation in said one path by said auxiliary valve and upon the fluid pressure at said shunt conduit exceeding the fluid pressure at said other path whereby a load energized through the control valve of said other path may draw upon medium from both said one of said paths and said other path.

Claim 4

A hydraulic system comprising: a plurality of pumps, each having a pressure side and an intake side; conduit means defining two distinct circulating paths including a respective circulating path for each of said pumps, eAch said conduit means including respective ducts connected to said pressure side and said intake side of each pump; two independently operable control valves including a respective control valve connecting each of said paths with a respective hydraulically operable load; a selectively shiftable auxiliary valve in at least one of said paths permitting circulation of a hydraulic medium therealong but actuatable to block such circulation, said auxiliary valve having a first position communicating between said duct connected to said pressure side and said duct connected to the intake side of the respective pump and permitting return flow of fluid from the respective path to the respective pump and a second position blocking return flow of fluid: a shunt conduit connecting said one of said paths, between said auxiliary valve and the pump associated with said one of said paths at the duct connected to the pressure side of the latter pump, with another of said paths; and an automatically operable check valve in said shunt conduit automatically opening upon shifting of said auxiliary valve into said second position for undirectional flow of the medium between said one of said paths and said other of said paths upon blockage of circulation in said one path by said auxiliary valve and upon the fluid pressure at said shunt conduit exceeding the fluid pressure at said other path whereby a load energized through the control valve of said other path may draw upon medium from both said one of said paths and said other path.

Claim 5

The system defined in claim 1 further comprising common actuating means for said auxiliary valve and said control valve of said other of said paths.

Claim 6

The system defined in claim 1 further comprising means interconnecting said auxiliary valve and at least one of said control valves for joint operation.

Claim 7

A hydraulic system comprising: a plurality of pumps, each having a pressure side and an intake side; conduit means defining a respective circulating path for each of said pumps, said conduit means including respective ducts connected to said pressure side and said intake side of each pump; a respective control valve connecting each of said paths with a respective hydraulically operable load; a selectively shiftable auxiliary valve in at least one of said paths permitting circulation of a hydraulic medium therealong but actuatable to block such circulation, said auxiliary valve having a first position communicating between said duct connected to said pressure side and said duct connected to the intake side of the respective pump and permitting return flow of fluid from the respective path to the respective pump and a second position blocking return flow of fluid; a shunt conduit connecting said one of said paths, between said auxiliary valve and the pump associated with said one of said paths at the duct connected to the pressure side of the latter pump, with another of said paths; an automatically operable check valve in said shunt conduit automatically opening upon shifting of said auxiliary valve into said second position for undirectional flow of the medium between said one of said paths and said other of said paths upon blockage of circulation in said one path by said auxiliary valve and upon the fluid pressure at said shunt conduit exceeding the fluid pressure at said other path whereby a load energized through the control valve of said other path may draw upon medium from both said one of said paths and said other path; and means interconnecting said auxiliary valve and at least one of said control valves for joint operation, said control valve of said other of said paths being provided with reversibly energizable hydraulic actuators and said actuating means includes transformation valve means energizable in parallel with said actuators for generating a control pressure regardless of the sense of operation of the control valve of said other paths, said auxiliary valve including a fluid-responsivE member coupled with said transformation valve means for actuation by said control pressure.

Claim 8

A hydraulic system comprising: a plurality of pumps, each having a pressure side and an intake side; conduit means defining a respective circulating path for each of said pumps, said conduit means including respective ducts connected to said pressure side and said intake side of each pump; a respective control valve connecting each of said paths with a respective hydraulically operable load; a selectively shiftable auxiliary valve in at least one of said paths permitting circulation of a hydraulic medium therealong but actuatable to block such circulation, said auxiliary valve having a first position communicating between said duct connected to said pressure side and said duct connected to the intake side of the respective pump and permitting return flow of fluid from the respective path to the respective pump and a second position blocking return flow of fluid; a shunt conduit connecting said one of said paths, between said auxiliary valve and the pump associated with said one of said paths at the duct connected to the pressure side of the latter pump, with another of said paths; an automatically operable check valve in said shunt conduit automatically opening upon shifting of said auxiliary valve into said second position for undirectional flow of the medium between said one of said paths and said other of said paths upon blockage of circulation in said one path by said auxiliary valve and upon the fluid pressure at said shunt conduit exceeding the fluid pressure at said other path whereby a load energized through the control valve of said other path may draw upon medium from both said one of said paths and said other path; and means interconnecting said auxiliary valve and at least one of said control valves for joint operation, said control valve of said other of said paths being provided with reversibly energizable hydraulic actuators and said actuating means includes transformation valve means energizable in parallel with said actuators for generating a control pressure regardless of the sense of operation of the control valve of said other paths, said auxiliary valve including a fluid-responsivE member coupled with said transformation valve means for actuation by said control pressure.

Claim 9

A hydraulic system comprising: a plurality of pumps, each having a pressure side and an intake side; conduit means defining a respective circulating path for each of said pumps, said conduit means including respective ducts connected to said pressure side and said intake side of each pump; a respective control valve connecting each of said paths with a respective hydraulically operable load; a selectively shiftable auxiliary valve in at least one of said paths permitting circulation of a hydraulic medium therealong but actuatable to block such circulation, said auxiliary valve having a first position communicating between said duct connected to said pressure side and said duct connected to the intake side of the respective pump and permitting return flow of fluid from the respective path to the respective pump a second position blocking return flow of fluid; a shunt conduit connecting said one of said paths, between said auxiliary valve and the pump associated with said one of said paths at the duct connected to the pressure side of the latter pump, with another of said paths; an automatically operable check valve in said shunt conduit automatically opening upon shifting of said auxiliary valve into said second position for unidirectional flow of the medium between said one of said paths and said other of said paths upon blockage of circulation in said one path by said auxiliary valve and upon the fluid pressure at said shunt conduit exceeding the fluid pressure at said other path whereby a load energized through the control valve of said other path may draw upon medium from both said one of said paths and said other path; and means interconnecting said auxiliary valve and at least one of said control valves for joint operation, said auxiliary valve being so constructed and arranged as to maintain communication between said shunt conduit and said one path in both blocking and nonblocking positions of said auxiliary valve.

Claim 10

A hydraulic system comprising: a plurality of pumps, each having a pressure side and an intake side; conduit means defining a respective circulating path for each of said pumps, said conduit means including respective ducts connected to said pressure side and said intake side of each pump; a respective control valve connecting each of said paths with a respective hydraulically operable load; a selectively shiftable auxiliary valve in at least one of said paths permitting circulation of a hydraulic medium therealong but actuatable to block such circulation, said auxiliary valve having a first position communicating between said duct connected to said pressure side and said duct connected to the intake side of the respective pump and permitting return flow of fluid from the respective path to the respective pump a second position blocking return flow of fluid; a shunt conduit connecting said one of said paths, between said auxiliary valve and the pump associated with said one of said paths at the duct connected to the pressure side of the latter pump, with another of said paths; an automatically operable check valve in said shunt conduit automatically opening upon shifting of said auxiliary valve into said second position for unidirectional flow of the medium between said one of said paths and said other of said paths upon blockage of circulation in said one path by said auxiliary valve and upon the fluid pressure at said shunt conduit exceeding the fluid pressure at said other path whereby a load energized through the control valve of said other path may draw upon medium from both said one of said paths and said other path; and means interconnecting said auxiliary valve and at least one of said control valves for joint operation, said auxiliary valve being so constructed and arranged as to maintain communication between said shunt conduit and said one path in both blocking and nonblocking positions of said auxiliary valve.

Claim 11

The system defined in claim 5 wherein said other path is formed with a respective auxiliary valve actuatable for the selective blocking and unblocking of flow of the medium through said other path, said paths each including a pressureless return line for carrying medium to the intake side of the respective pump, each of said auxiliary valves being disposed between the respective control valve and return line of the corresponding path, said system further comprising another shunt conduit communicating with said other path between its control valve and auxiliary valve and connected to said one path between the pump thereof and the control valve of said one path at the duct connected to the pressure side of the latter pump, said other shunt conduit including a check valve permitting unidirectional flow of medium from said other path to said one path upon the blockage of circulation in said other path by the auxiliary valve associated therewith and upon the further shunt conduit exceeding the pressure in said one path.

Claim 12

The system defined in claim 6 wherein said pumps of said one and said other paths are provided with a common reservoir and a common drive, said return lines emptying into said reservoir, each of said paths being provided with a plurality of control valves each energizing when operated a respective load and disposed along said path between the respective pump and auxiliary valve, the control valves of each path being so constructed and arranged as to block, upon operation, the flow of the medium to the respective auxiliary valve.

Claim 13

The system defined in claim 7 for an excavator in which said loads include rotary hydraulic motors and piston-and-cylinder arrangements connected with said control valves.

Claim 14

The system defined in claim 3 wherein said control valve is formed in a valve block provided with a circulating duct and a return duct branching from said circulating duct, said auxiliary valve coMprising a housing mounted on said block, a pressure responsive valve member shiftable in said piston for selectively blocking and unblocking communication between said circulating and return ducts, and means for connecting said shunt conduit to said housing.

Claim 15

A hydraulic system comprising : a plurality of pumps; conduit means defining a respective circulating path including each of said pumps; a respective control valve connecting each of said paths with a respective hydraulically operable load; an auxiliary valve in at least one of said paths permitting circulation of a hydraulic medium therealong but actuatable to block such circulation; a shunt conduit connecting said one of said paths with another of said paths between said auxiliary valve and the pump associated with said one of said path; a check valve in said shunt conduit for undirectional flow of the medium between said one of said paths and said other of said paths upon blockage of circulation in said one of path by said auxiliary valve and upon the fluid pressure at said shunt conduit exceeding the fluid pressure at said other path whereby a load energized through the control valve of said other path may draw upon medium from both said one of said paths and said other path; common actuating means for said auxiliary valve and said control valve of said other of said paths; said control valve of said other of said paths being provided with reversibly energizable hydraulic actuators and said actuating means including transformation valve means energizable in parallel with said actuators for generating a control pressure regardless of the sense of operation of the control valve of said other path, said auxiliary valve including a fluid-responsive member coupled with said transformation valve for actuation by said control pressure.

Claim 16

A hydraulic system comprising : a plurality of pumps; conduit means defining a respective circulating path including each of said pumps; a respective control valve connecting each of said paths with a respective hydraulically operable load; an auxiliary valve in at least one of said paths permitting circulation of a hydraulic medium therealong but actuatable to block such circulation; a shunt conduit connecting said one of said paths with another of said paths between said auxiliary valve and the pump associated with said one of said path; a check valve in said shunt conduit for undirectional flow of the medium between said one of said paths and said other of said paths upon blockage of circulation in said one of path by said auxiliary valve and upon the fluid pressure at said shunt conduit exceeding the fluid pressure at said other path whereby a load energized through the control valve of said other path may draw upon medium from both said one of said paths and said other path; common actuating means for said auxiliary valve and said control valve of said other of said paths; said control valve of said other of said paths being provided with reversibly energizable hydraulic actuators and said actuating means including transformation valve means energizable in parallel with said actuators for generating a control pressure regardless of the sense of operation of the control valve of said other path, said auxiliary valve including a fluid-responsive member coupled with said transformation valve for actuation by said control pressure.

Claim 17

the system defined in claim 10 wherein said auxiliary valve is so constructed and arranged as to block communication between said one path and said shunt conduit when circulation along said one path is permitted.

Claim 18

The system defined in claim 10 wherein said auxiliary valve is so constructed and arranged as to maintain communication between said shunt conduit and said one path in both blocking and nonblocking positions of said auxiliary valve.

Claim 19

the system defined in claim 12 wherein said other path is formed with a respective auxiliary valve actuatable for the selective blocking and unblocking of flow of the medium through said other path, said paths each including a pressureless return line for carrying medium to the respective pump, each of said auxiliary valves being disposed between the respective control valve and return line along the corresponding paths, said shunt conduit communicating with said one path between its control valve and auxiliary valve, said system further comprising another shunt conduit communicating with said other path between its control valve and auxiliary valve and connected to said one path between the pump thereof and the control valve of said one path, said other shunt conduit including a check valve permitting unidirectional flow of medium from said other path to said one path upon the blockage of circulation of said other path by the auxiliary valve associated therewith and upon the further shunt conduit exceeding the pressure in said one path.

Claim 20

The system defined in claim 13 wherein said pumps of said one and said other paths are provided with a common reservoir and a common drive, said return lines emptying into said reservoir, each of said paths being provided with a plurality of control valves each energizing a respective load and disposed along said path between the respective pump and auxiliary valve, the control valves of each path being so constructed and arranged as to block, upon operation, the flow of the medium to the respective auxiliary valve.

Claim 21

The system defined in claim 14 for an excavator in which said loads include rotary hydraulic motors and piston-and-cylinder arrangementS connected with said control valves.

Claim 22

The system defined in claim 10 wherein said control valve is formed in a valve block provided with a circulating duct and a return duct branching from said circulating duct, said auxiliary valve comprising a housing mounted on said block, a pressure responsive valve member shiftable in said piston for selectively blocking and unblocking communication between said circulating and return ducts, and means, for connecting said shunt conduit to said housing.

Claim 23

A hydraulic system comprising: a plurality of pumps each having an intake side and a pressure side; conduit means defining a respective circulating path including each of said pumps; a respective control valve connecting each of said paths with a respective hydraulically operable load; an auxiliary valve in at least one of said paths permitting circulation of a hydraulic medium therealong but actuatable to block such circulation; a shunt conduit connecting said one of said paths with another of said paths, said shunt conduit communicating with said one of said paths between said auxiliary valve and the pressure side of the pump associated with said one of said paths; a check valve in said shunt conduit for unidirectional flow of the medium between said one of said paths and said other of said paths upon blockage of circulation in said one path by said auxiliary valve and upon the fluid pressure at said shunt conduit exceeding the fluid pressure at said other path whereby a load energized through the control valve of said other path may draw upon medium from both said one of said paths and said other path, said auxiliary valve being so constructed and arranged as to maintain communication between said shunt conduit and said one path in both the blocking and nonblocking positions of said auxiliary valve, said other path being formed with a respective auxiliary valve actuatable for the selective blocking and unblocking of flow of the medium through said other path, said paths each including a pressureless return line for carrying medium to the respective pump, each of said auxiliary valves being disposed between the respective control valve and return line along the corresponding paths; another shunt conduit communicating with said other path between its control valve and auxiliary valve and connected to said one path between the pressure side of the pump thereof and the control valve of said one path, said other shunt conduit including a check valve permitting unidirectional flow of medium from said other path to said one path upon the blockage of circulation of said other path by the auxiliary valve associated therewith and upon the further shunt conduit exceeding the pressure in said one path, said pumps of said one and said other paths being provided with a common reservoir and a common drive, said return lines emptying into said reservoir, each of said paths being provided with a plurality of control valves each energizing a respective load and disposed along said path between the respective pump and auxiliary valve, the control valves of each path being so constructed and arranged as to block, upon operation, the flow of the medium to the respective auxiliary valve, at least one of said control valves being provided with a pair of hydraulic actuators for reversible operation of said one of said control valves and the load associated therewith; and a transformation valve connected to said actuators for producing a control pressure regardless of the direction of operation of said one of said control valves and the load associated therewith and conduit means for applying said control pressure to the auxiliary valve of a path other than that of said one of said control valves.

Claim 24

A hydraulic system comprising: a plurality of pumps each having an intake side and a pressure side; conduit means defining a respective circulating path including each of said pumps; a respective control valve connecting each of said paths with a respective hydraulically operable load; an auxiliary valve in at least one of said paths permitting circulation of a hydraulic medium therealong but actuatable to block such circulation; a shunt conduit connecting said one of said paths with another of said paths, said shunt conduit communicating with said one of said paths between said auxiliary valve and the pressure side of the pump associated with said one of said paths; a check valve in said shunt conduit for unidirectional flow of the medium between said one of said paths and said other of said paths upon blockage of circulation in said one path by said auxiliary valve and upon the fluid pressure at said shunt conduit exceeding the fluid pressure at said other path whereby a load energized through the control valve of said other path may draw upon medium from both said one of said paths and said other path, said auxiliary valve being so constructed and arranged as to maintain communication between said shunt conduit and said one path in both the blocking and nonblocking positions of said auxiliary valve, said other path being formed with a respective auxiliary valve actuatable for the selective blocking and unblocking of flow of the medium through said other path, said paths each including a pressureless return line for carrying medium to the respective pump, each of said auxiliary valves being disposed between the respective control valve and return line along the corresponding paths; another shunt conduit communicating with said other path between its control valve and auxiliary valve and connected to said one path between the pressure side of the pump thereof and the control valve of said one path, said other shunt conduit including a check valve permitting unidirectional flow of medium from said other path to said one path upon the blockage of circulation of said other path by the auxiliary valve associated therewith and upon the further shunt conduit exceeding the pressure in said one path, said pumps of said one and said other paths being provided with a common reservoir and a common drive, said return lines emptying into said reservoir, each of said paths being provided with a plurality of control valves each energizing a respective load and disposed along said path between the respective pump and auxiliary valve, the control valves of each path being so constructed and arranged as to block, upon operation, the flow of the medium to the respective auxiliary valve, at least one of said control valves being provided with a pair of hydraulic actuators for reversible operation of said one of said control valves and the load associated therewith; and a transformation valve connected to said actuators for producing a control pressure regardless of the direction of operation of said one of said control valves and the load associated therewith and conduit means for applying said control pressure to the auxiliary valve of a path other than that of said one of said control valves.

Claim 25

The system defined in claim 17 wherein said control valve is formed in a valve block provided with a circulating duct and a return duct branching from said circulating duct, said auxiliary valve comprising a housing mounted on said block, a pressure respoNsive valve member shiftable in said piston for selectively blocking and unblocking communication between said circulating and return ducts, and means for connecting said shunt conduit to said housing.