초록 ▼

A hydraulic system is disclosed for use with a machine. The hydraulic system may have a pump configured to pressurize fluid, a first actuator configured to receive pressurized fluid from the pump, and an accumulator configured to receive fluid from the first actuator. The hydraulic system may also h

A hydraulic system is disclosed for use with a machine. The hydraulic system may have a pump configured to pressurize fluid, a first actuator configured to receive pressurized fluid from the pump, and an accumulator configured to receive fluid from the first actuator. The hydraulic system may also have a second actuator configured to receive pressurized fluid from the pump and the accumulator, and a pilot circuit configured to receive pressurized fluid from the pump and the accumulator. The hydraulic system may further have at least one valve movable to provide priority of fluid flow from the accumulator to the pilot circuit over the second actuator when a pressure of the accumulator is less than a low-pressure threshold.

대표청구항 ▼

1. A hydraulic system, comprising: a pump configured to pressurize fluid;a first actuator configured to receive pressurized fluid from the pump;an accumulator configured to receive fluid from the first actuator;a second actuator configured to receive pressurized fluid from the pump and the accumulat

1. A hydraulic system, comprising: a pump configured to pressurize fluid;a first actuator configured to receive pressurized fluid from the pump;an accumulator configured to receive fluid from the first actuator;a second actuator configured to receive pressurized fluid from the pump and the accumulator;a pilot circuit configured to receive pressurized fluid from the pump and the accumulator;at least one valve movable to provide priority of fluid flow from the accumulator to the pilot circuit over the second actuator when a pressure of the accumulator is less than a low-pressure threshold; anda pressure control valve configured to selectively allow pressurized fluid from the accumulator into the pilot circuit only when a pressure of the pressurized fluid in the accumulator is greater than a pressure of fluid being discharged by the pump. 2. The hydraulic system of claim 1, wherein the at least one valve is configured to selectively block fluid flow from the accumulator to the second actuator. 3. The hydraulic system of claim 2, further including: a pressure sensor configured to generate a signal indicative of a pressure of fluid in the accumulator; anda controller in communication with the pressure sensor and the at least one valve, the controller being configured to command movement of the at least one valve to a flow-blocking position based on the signal. 4. The hydraulic system of claim 1, wherein: the first actuator is a boom cylinder; andthe second actuator is a fan motor. 5. The hydraulic system of claim 4, further including: a boom control valve movable to regulate fluid flow from the pump to the boom cylinder;an operator input device movable to indicate a desired movement of the boom cylinder; anda pilot valve connected to the operator input device and configured to selectively direct pilot fluid from the pilot circuit to move the boom control valve. 6. The hydraulic system of claim 5, further including a pressure control valve configured to direct pilot fluid from the pilot circuit to the boom control valve. 7. The hydraulic system of claim 6, further including a shuttle valve disposed between the boom control valve and the pilot and pressure control valves, the shuttle valve configured to pass only a higher-pressure flow from one of the pilot and pressure control valves to the boom control valve. 8. The hydraulic system of claim 6, further including: a low-pressure reservoir configured to receive fluid from the boom cylinder and the fan motor; anda controller in communication with the pressure control valve, the controller being configured to command movement of the pressure control valve that causes the boom control valve to vary a restriction placed on fluid being discharged from the boom cylinder to the low-pressure reservoir, wherein the restriction is proportional to a pressure of fluid being received by the accumulator. 9. The hydraulic system of claim 6, further including a fan control valve disposed between the pump and the fan motor. 10. The hydraulic system of claim 9, further including a directional control valve disposed downstream of the at least one valve and the fan control valve. 11. The hydraulic system of claim 1, further including an accumulator control valve disposed between the first actuator and the accumulator. 12. The hydraulic system of claim 1, wherein: the at least one valve is a first valve; andthe hydraulic system further includes: a third actuator configured to receive pressurized fluid from the accumulator and from the pump. 13. The hydraulic system of claim 1, wherein: the accumulator is a first accumulator; andthe hydraulic system further includes a second accumulator configured to receive fluid from the first actuator in parallel with the first accumulator. 14. A machine, comprising: a frame;a boom pivotally connected to the frame;a boom cylinder configured to move the boom;an engine supported by the frame;a fan configured to cool the engine;a fan motor configured to drive the fan;a pump driven by the engine to pressurize fluid directed to the boom cylinder and to the fan motor;a boom control valve disposed between the pump and the boom cylinder, the boom control valve movable to affect fluid flow from the pump into the boom cylinder;an operator input device movable to indicate a desire to raise or lower the boom;a pilot valve connected to the operator input device and movable to affect a flow of pilot fluid to the boom control valve;a pressure control valve movable to affect a flow of pilot fluid to the boom control valve;a shuttle valve disposed between the boom control valve and the pilot and pressure control valves;an accumulator configured to receive fluid discharged from the boom cylinder, and to discharge fluid to the fan motor and to the pilot and pressure control valves; anda priority valve configured to selectively block fluid flow from the accumulator to the fan motor when a pressure of the accumulator is less than a low-pressure threshold. 15. The machine of claim 14, further comprising: a pilot circuit configured to receive pressurized fluid from the pump and the accumulator;a pressure control valve configured to selectively allow pressurized fluid from the accumulator into the pilot circuit only when a pressure of the pressurized fluid in the accumulator is greater than a pressure of fluid being discharged by the pump. 16. The machine of claim 14, further comprising: a pilot circuit configured to receive pressurized fluid from the pump and the accumulator;a pressure control valve configured to direct pilot fluid from the pilot circuit to the boom control valve; anda low-pressure reservoir configured to receive fluid from the boom cylinder and the fan motor. 17. The machine of claim 16, further comprising: a controller in communication with the pressure control valve, the controller being configured to command movement of the pressure control valve that causes the boom control valve to vary a restriction placed on fluid being discharged from the boom cylinder to the low-pressure reservoir,wherein the restriction is proportional to a pressure of fluid being received by the accumulator. 18. A method of recovering energy, the method comprising: pressurizing fluid at a first location;directing pressurized fluid from the first location through a control valve to a first actuator and to a second actuator, the first actuator being a boom cylinder;accumulating fluid discharged from the first actuator;directing the accumulated fluid to the second actuator and to a pilot circuit associated with the first actuator;selectively inhibiting the accumulated fluid from flowing to the second actuator based on a pressure of the accumulated fluid; andselectively restricting fluid discharge from the boom cylinder to a low-pressure reservoir to increase a pressure of the accumulated fluid, selectively restricting the fluid discharge including selectively overriding a pilot signal directed to a control valve associated with the boom cylinder. 19. The method of claim 18, further including sensing the pressure of the accumulated fluid, wherein selectively inhibiting includes selectively inhibiting accumulated fluid from flowing to the second actuator when a pressure of the accumulated fluid falls below a low-pressure threshold. 20. The method of claim 18, wherein: the second actuator is a fan motor; andaccumulating fluid includes accumulating fluid from a head end of the boom cylinder during a retraction operation.