Caterpillar Inc.

Other

Srikrishnan T Tolappa

Thomas J Hajek

Michael Anthony A'Hearn

Daniel T Mather

Tony L Marcott

Michael D Hudson

Lawrence F Schexnayder

Edward William Mate

James Alvin Aardema

Larry W Lorimor

Patrick Quinn

David J Carlson

James D Linderode

Andy Hatcher

A fluid system is provided wherein two different fluid circuits are connected in parallel with a single source of pressurized fluid and the two fluid circuits can function together even when one of the loads is lighter than the other. This is accomplished by having the lightly loaded circuit having a directional control that when operated in one of its operative positions the flow from the rod end of the cylinder is directed through the directional control valve and combined with the supply flow being directed to the head end of the cylinder. With the other heavier loaded circuit also being actuated, the pressure of the fluid from the rod end of the fluid cylinder is equalized with the pressure of the heavier loaded circuit. Consequently, the speed of the heavier loaded circuit does not stall or slow down relative to the lightly loaded circuit. In the case of a machine having a bucket used for backdragging, the circuit needs a diverter system that provides protection from the cylinder rod of the fluid cylinderfrom buckling during backdragging while maintaining the ability for pressure equalization when not performing a backdragging operation.

Hydraulic circuit having pressure equalization during regeneration

A fluid control system is disclosed that includes a reservoir, a pump in fluid communication with the reservoir, a first double-acting actuator having a first head end chamber and a first rod end chamber, a second double-acting actuator having a second head end chamber and a second rod end chamber. The first and second double-acting actuators are selectively fluidly connected via a conduit. A first independent metering valve is configured to selectively provide fluid flow to the first and second double-acting actuators, and a second independent metering valve is configured to selectively provide fluid flow to the first and second double-acting actuators. The fluid control system also includes a proportional valve attached to the conduit between the first double-acting actuator and the second double-acting actuator. The proportional valve is capable of operating the fluid control system in either an independent function mode or a regenerative function mode.

Independent and regenerative mode fluid control system

A fluid control system is disclosed that includes a first double-acting actuator and a second double-acting actuator. A first independent metering valve has a first control port connected to the first double-acting actuator, a second control port connected to the second double-acting actuator, first and second independently operable valves disposed between the inlet port and the first and second control ports, and a first check control mechanism having a main check valve between the inlet port and the first and second independently operable valves. The first check control mechanism controls the main check valve to allow the first and second actuators to operate in either an independent function mode or a regenerative function mode. A second independent metering valve has a first control port connected to the first double-acting actuator, a second control port connected to the second double-acting actuator, first and second independently operable valves disposed between the inlet port and the first and second control ports, and a main check valve disposed between the inlet port and the first and second independently operable valves.

A hydraulic ride control system is disclosed and adapted to control the ride of a machine having a load. The ride control includes an accumulator arrangement that is selectively connected with the actuator that is carrying the load to provide a cushion ride during traveling and to enable the pressure in the accumulator arrangement to be maintained substantially the same as the pressure in the actuator when raising the load and to permit the pressure in the accumulator arrangement to be lowered to that of the pressure in the actuator in the event the load is lessened. The ride control system also provides an arrangement that permits the accumulator arrangement to be bled down whenever the machine becomes disabled or when the machine is shut off.

Hydraulic ride control system

A ride control system adapted for use in a fluid system of a machine to cushion the ride of the machine, the machine having a frame with an actuator arrangement disposed between the frame and a load to raise the load relative to the frame, the actuator arrangement having a raise port and being operative in a raise mode to raise the load to a desired height in response to pressurized fluid being directed to the raise port from a source of the pressurized fluid, the ride control system including an accumulator arrangement and a valve arrangement connected between the accumulator arrangement, the actuator arrangement, and the source of pressurized fluid, and operative to selectively connect the accumulator arrangement to the raise port of the actuator arrangement when in the raise mode while maintaining the load at the desired height.

Ride control

A control system is provided with a float condition to permit a double acting hydraulic cylinder to freely extend or retract in response to external forces acting on the hydraulic cylinder. The system includes a pair of pilot operated poppet valves disposed between the opposite sides of the hydraulic cylinder and a directional control valve. The pilot condition is obtained by opening a pair of pilot operated control valves to vent the control chambers of the poppet valves to a tank through a pair of float check valves. The float check valves are operative to prevent higher pressure fluid from being transmitted from the tank to the control chambers of the poppet valves when a negative pressure occurs in the side of the hydraulic cylinder that is connected to the control chamber.

Control system providing a float condition for a hydraulic cylinder

A fluid control system provides a float capability for a double-acting actuator. The system includes pilot operated check valves disposed between the double-acting actuator and first and second ports of a pilot operated directional control valve. The directional control valve and the check valves are cooperatively operable under first and second pilot signal conditions to extend and retract the double-acting actuator. The system includes a valve arrangement connected to the check valves and the directional control valve for producing the first and second pilot signal conditions thereon, including also directing the first pilot signal condition to the second pilot signal condition when the first pilot signal condition reaches a predetermined signal strength, to initiate a float capability.

Fluid control system with float capability

A fluid control circuit providing a float capability for a double-acting actuator having first and second actuating chambers is provided. The fluid circuit includes signal controlled load check valves disposed between the actuating chambers and a directional control valve. The directional control valve is movable from a centered, neutral position towards first and second operative positions and a float position. The directional control valve and the load check valves are cooperatively operable in one operable position to allow fluid flow from the first actuating chamber to the exhaust port, and fluid flow from the pump port to the second actuating chamber. In the float position of the directional control valve, both of the signal controlled load check valves are opened to allow open fluid flow between the first and second actuating chambers thus allowing the tool attached to the actuator to float.

Fluid control system having float control

A fluid control system including a control valve providing a simple, easy to use regeneration capability in association with a pump, a tank, and a double acting actuator having a first actuating chamber and a second actuating chamber. The control valve has a first actuating chamber port connected to the first actuating chamber, a second actuating chamber port connected to the second actuating chamber, a tank port connected to the tank, a first pump port and a second pump port. The control valve includes a connecting passage connecting the first pump port and the second pump port to the pump, and is operable in a first position to allow fluid flow from the pump through the first pump port and the first actuating chamber port to the first actuating chamber and fluid flow from the second actuating chamber through the second actuating chamber port and the tank port to the tank. For regeneration, the control valve member is movable from the first position to a second position to allow the fluid flow from the second actuating chamber port to be diverted to the second pump port such that the fluid flow can pass through the connecting passage to the first pump port and through the first actuating chamber port to the first actuating chamber of the actuator.

Fluid control system with regeneration

A control for a poppet valve providing improved load drift control is disclosed. The control includes a valve member operably moveable between a closed position and a range of open positions for allowing flow from an associated poppet control chamber, and a sealing element disposed between a first cavity portion in communication with the control chamber and a second cavity portion for preventing leakage around the valve member therebetween. The sealing element is supported by structure which maintains the sealing element in close alignment with a bore in which the valve member is supported, the sealing element in several embodiments being integrally formed with the bore and in other embodiments being self aligning with the bore.

Poppet valve control with sealing element providing improved load drift

A valve interface provides a zero leak function for an area control valve. The valve interface is established by sealing contact between a concave valve face and a convex valve seat having mismatched radii. The concave valve face is formed on a valve element slidably disposed in a bore of a housing and the convex valve seat is formed in the housing and intersects with the bore.

Valve interface having mismatched radii

A low cost, electromagnetic efficient integrated electrohydraulic actuator includes a sleeve disposed within a housing and an annular electric coil formed as an integral part of the sleeve so that the coil is deeply integrated in the housing. An armature slidably disposed within an axial bore of the sleeve has the fluid metering functions integrally formed thereon so that the armature functions as a valve spool for controlling communication between an inlet port and an outlet port and between the outlet port and a tank port. The armature is thus the only movable part of the actuator.

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Aurora, IL, United States of America

Srikrishnan T Tolappa