System for recovering energy in hydraulic circuit

• US 6,789,387 B2
• Filed: 10/01/2002
• Issued: 09/14/2004
• Est. Priority Date: 10/01/2002
• Status: Expired due to Fees

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Brinkman, Jason L.
• Primary Examiner(s): Lazo, Thomas E.
• Application Number:
  US10/260,272
• Publication Number:
  US 20040060430A1
• Time in Patent Office: 714 Days
• Field of Search: 604/13, 604/14, 604/35, 604/45, 604/59
• US Class Current: 60/414
• CPC Class Codes: E02F 9/2217 with energy recovery arrangements, e.g. using accumulators, flywheels
• CPC Class Codes: E02F 9/2228 including an electronic controller
• CPC Class Codes: E02F 9/2285 Pilot-operated systems
• CPC Class Codes: E02F 9/2296 Systems with a variable displacement pump
• CPC Class Codes: F15B 1/024 used as a supplementary power source, e.g. to store energy in idle periods to balance pump load
• CPC Class Codes: F15B 21/082 with different modes
• CPC Class Codes: F15B 21/14 Energy-recuperation means

Abstract

A method is provided for recovering energy in a hydraulic circuit. The hydraulic circuit includes a pump having a swashplate and being in fluid communication with a hydraulic actuator via a valve. The method includes sensing an overrunning load condition in the hydraulic circuit, actuating the valve to provide fluid from the hydraulic actuator to the pump under the overrunning load condition, and producing a torque output from the fluid provided to the pump. Also, a method is provided for recovering energy in a hydraulic circuit including a pump and a motor in fluid communication with a hydraulic actuator via a valve. The method includes sensing an overrunning load condition in the hydraulic circuit, actuating the valve to provide fluid from the hydraulic actuator to the motor under the overrunning load condition, and producing a torque output from the fluid provided to the motor.

Claims

1. A method for recovering energy in a hydraulic circuit including a pump having a swashplate and being in fluid communication with a hydraulic actuator via a valve, the method comprising:

sensing an overrunning load condition in the hydraulic circuit;

actuating the valve to provide fluid from the hydraulic actuator to the pump under the overrunning load condition;

producing a torque output from the fluid provided to the pump; and

supplying fluid to the hydraulic circuit when the overrunning load condition ends and fluid pressure in the hydraulic circuit reaches a fluid supply pressure.

2. The method of claim 1, further including accumulating the fluid from the hydraulic circuit in a chamber prior to supplying the fluid to the hydraulic circuit.

3. The method of claim 1, wherein the overrunning load condition sensing step includes monitoring a pressure of the hydraulic actuator and an operating command of the hydraulic actuator.

4. The method of claim 1, wherein the hydraulic actuator is operated as a pressure intensifier when the overrunning load condition is sensed.

5. The method of claim 1, wherein the torque producing step includes tilting the swashplate of the pump to an over-center position so that the pump functions as a motor.

6. The method of claim 5, wherein the swashplate of the pump is tilted to the over-center position when the overrunning load condition is sensed.

7. The method of claim 5, further including tilting the swashplate of the pump from the over-center position to a non-over-center position when the overrunning load condition ends so that the pump functions as a pump.

8. The method of claim 1, wherein the pump is coupled to a power source, and further including transferring the produced torque output to the power source.

9. The method of claim 8, further including controlling the power source to optimize efficiency of the power source.

10. A method for recovering energy in a hydraulic circuit including a pump and a motor in fluid communication with a hydraulic actuator via a valve, the method comprising:

sensing an overrunning load condition in the hydraulic circuit;

actuating the valve to provide fluid from the hydraulic actuator to the motor under the overrunning load condition; and

producing a torque output from the fluid provided to the motor.

11. The method of claim 10, wherein the overrunning load condition sensing step includes monitoring pressure and an operating command of the hydraulic actuator.

12. The method of claim 10, wherein the hydraulic actuator is operated as a pressure intensifier when the overrunning load condition is sensed.

13. The method of claim 12, wherein the torque is provided from the motor to the power source via a one-way clutch.

14. The method of claim 10, further including providing the produced torque to a power source.

15. The method of claim 14, wherein the one-way clutch engages and disengages a motor output shaft and a power source output shaft.

16. The method of claim 15, wherein the one-way clutch engages the motor and the power source when the motor output shaft drives the power source output shaft.

17. The method of claim 15, wherein the one-way clutch disengages the motor and the power source when the motor output shaft rotates slower than the power source output shaft.

18. The method of claim 15, further including transferring the produced torque output to the power source when the motor is engaged with the power source.

19. The method of claim 18, further including controlling the power source to optimize efficiency of the power source.

20. A system for recovering energy in a hydraulic circuit, comprising:

a pump having a swashplate tiltable to direct flow between a valve and a reservoir;

a hydraulic actuator in fluid communication with the pump via the valve and a conduit, the valve being configured to provide fluid from the hydraulic actuator to the pump under an overrunning load condition;

a sensor assembly in communication with the hydraulic circuit;

a control unit electrically coupled to the valve and the sensor and assembly; and

a fluid supply valve in fluid communication with the pump, the fluid supply valve being configured to open to supply fluid to the conduit when the overrunning load condition ends and fluid pressure in the conduit reaches to a fluid supply pressure.

21. The system of claim 20, wherein the fluid supply valve is a check valve in fluid communication with the conduit and the reservoir.

22. The system of claim 20, further including an accumulator and wherein the fluid supply valve is a second valve in fluid communication with the conduit and the accumulator.

23. The system of claim 22, wherein the second valve includes first and second valve positions, the first valve position being configured to supply the fluid from the conduit to the accumulator, the second valve position being configured to supply the fluid in the accumulator to the conduit.

24. The system of claim 20, wherein the swashplate of the pump is tilted to an over-center position so that the pump functions as a motor.

25. The system of claim 24, wherein the swashplate of the pump is tilted to the over-center position under the overrunning load condition.

26. The system of claim 24, wherein the swashplate of the pump is tilted from the over-center position to a non-over-center position when the overrunning load condition ends so that the pump functions as a pump.

27. The system of claim 20, wherein the hydraulic actuator is a hydraulic cylinder.

28. The system of claim 20, herein the valve is an independent metering valve assembly.

29. The system of claim 20, wherein the valve includes first and second valve positions, the first valve position being configured to supply the fluid from the pump to the hydraulic actuator, the second valve position being configured to supply the fluid from the hydraulic actuator to the pump.

30. The system of claim 20, wherein the sensor assembly includes a plurality of pressure sensors that monitor pressure of the hydraulic actuator.

31. The system of claim 30, wherein the control unit monitors an operating command of the hydraulic actuator and senses the overrunning load condition based on the operating command and the monitored pressure of the hydraulic actuator.

32. The system of claim 20, wherein the pump is coupled to a power source, the pump providing a torque output to the power source under the overrunning load condition.

33. A system for recovering energy in a hydraulic circuit, comprising:

a pump;

a hydraulic actuator in fluid communication with the pump via a valve and a conduit;

a motor in fluid communication with the hydraulic actuator via the valve, the valve being configured to provide fluid from the hydraulic actuator to the motor under an overrunning load condition;

a sensor assembly in communication with the hydraulic circuit; and

a control unit electrically coupled to the valve and the sensor assembly.

34. The system of claim 33, wherein the hydraulic actuator is a hydraulic cylinder.

35. The system of claim 33, wherein the valve is an independent metering valve assembly.

36. The system of claim 33, wherein the valve includes first and second valve positions, the first valve position being configured to supply the fluid from the pump to the hydraulic actuator, the second valve position being configured to supply the fluid from the hydraulic actuator to the motor.

37. The system of claim 33, wherein the sensor assembly includes a plurality of pressure sensors that monitor pressure of the hydraulic actuator.

38. The system of claim 33, wherein the control unit monitors an operating command of the hydraulic actuator and senses the overrunning load condition based on the operating command and the monitored pressure of the hydraulic actuator.

39. The system of claim 33, wherein the motor is configured to be coupled to a power source.

40. The system of claim 39, further including a one-way clutch, the motor being configured to be coupled to the power source via the one-way clutch.

41. The system of claim 40, wherein the one-way clutch includes a first rotatable clutch element coupled to the power source and a second rotatable clutch element coupled to the motor.

42. The system of claim 41, wherein the first and second rotatable clutch elements engage when the second rotatable clutch element drives the first rotatable clutch element.

43. The system of claim 41, wherein the first and second rotatable clutch elements disengage when the second rotatable clutch element rotates slower than the first rotatable clutch element.