Method and system for improving stability of hydraulic systems with load sense

A hydraulic circuit comprising:

• a flow control element, a pressure compensator connected via a pair of load sense lines to an inlet line and an outlet line, respectively, of a flow control element to provide a constant pressure drop across the flow control element, and a load sense line control valve installed in a load sense line to provide controllable resistance in a flow passage in opposite flow directions, the load sense line control valve having a spring loaded check valve to act in one flow direction and a non-loaded check valve to act in the opposite flow direction, the resistance in each flow direction being substantially different.

A load sense line control valve comprising:

• a restrictive orifice followed by a spring-loaded check valve in a first flow direction and at least one restrictive orifice and a check valve in a second flow direction, the second flow direction opposing the first flow direction, wherein a first restrictive orifice is located in a moveable washer positioned in a counterbore of a body element followed by a seat of a spring-loaded check valve, the seat having at least one additional restrictive orifice providing a flow passage in parallel to the spring-loaded check valve and a surface contacting the movable washer in one of its positions to overlap the additional orifice.

A pressure compensator valve comprising:

• a cage with two rows of lateral holes, an adaptor threaded on one side to a cage, and a plurality of seals engaged with the adaptor and the cage to form a cartridge that can be installed into a cavity formed in a body to create three separated cavities connected to respective inlet, outlet and load sense ports, a spool slidingly disposed within an axial bore of the cage and maintained in an initial position by a pre-loaded spring, an insert sub-assembly installed into the cage on a side opposite to adaptor, the insert sub-assembly including a load sense line control valve comprising a restrictive orifice followed by a spring loaded check valve in a first flow direction and at least one other restrictive orifice and a check valve in a second flow direction, the second flow direction opposing the first flow direction.

A hydraulic system having a load sense mechanism comprising:

• a hydraulic line connecting a load line to a control device for controlling pressure or flow in at least a part of the hydraulic system via a load sense line control device installed into a load sense line to provide controllable resistance to a flow passage in opposite flow directions, the load sense line control device including:
• a restrictive orifice followed by a spring-loaded check valve in a first flow direction and at least one restrictive orifice and a check valve in a second flow direction, the second flow direction opposing the first flow direction, wherein a first restrictive orifice is located in a moveable washer positioned in a counterbore of a body element followed by a seat of the spring-loaded check valve, the seat having at least one additional restrictive orifice providing a flow passage in parallel to the spring-loaded check valve and a surface contacting the movable washer in one of its positions to overlap the additional orifice.

A hydraulic circuit comprising a flow control element a pressure compensator connected with a pair of load sense lines to an inlet line and an outlet line, respectively, of a flow control element to provide a constant pressure drop across the flow control element, and a load sense line control valve installed in a load sense line to provide controllable resistance in a flow passage in opposite flow directions, the load sense line control valve having a moveable washer with a restrictive orifice and a spring-loaded check valve with a seat in a first flow direction, the spring-loaded check valve being downstream of the restrictive orifice relative to the first flow direction, and at least one restrictive orifice and a check valve in a second flow direction, the second flow direction opposing the first flow direction, wherein the moveable washer is disposed in a counterbore of a body element followed by the seat of the spring-loaded check valve, the seat having at least one additional restrictive orifice providing a flow passage in parallel to the spring-loaded check valve and a surface contacting the movable washer in one of its position to overlap the additional orifice.

A hydraulic circuit comprising a flow control element and a pressure compensator connected via a pair of load sense lines to an inlet line and an outlet line, respectively, of a flow control element the pressure compensator including a cage with two rows of lateral holes, an adaptor threaded on one side to the cage, and a plurality of seals engaged with the adaptor and the cage to form a cartridge that can be installed into a cavity formed in a body to create three separated cavities connected to respective inlet, outlet and load sense ports, a spool slidingly disposed within an axial bore of the cage, the spool maintained in an initial position by a pre-loaded spring, an insert sub-assembly installed into the cage on a side opposite to the adaptor, the insert subassembly including a load sense line control valve having a restrictive orifice followed by a spring-loaded check valve in a first flow direction and at least one restrictive orifice and a check valve in a second flow direction, the second flow direction opposing the first flow direction.