Energy regeneration system for working machinery

• US 20060090462A1
• Filed: 12/12/2005
• Published: 05/04/2006
• Est. Priority Date: 11/14/2003
• Status: Abandoned Application

• Current Assignee: Caterpillar Sarl (Caterpillar Incorporated)
• Original Assignee: Caterpillar Sarl (Caterpillar Incorporated)
• Inventors: Yoshino, Kazunori
• Application Number:
  US11/299,402
• Publication Number:
  US 20060090462A1
• Time in Patent Office: Days
• US Class Current: 60/468
• CPC Class Codes: E02F 9/2207 for reducing or compensating oscillations
• CPC Class Codes: E02F 9/2217 with energy recovery arrangements, e.g. using accumulators, flywheels
• CPC Class Codes: E02F 9/2296 Systems with a variable displacement pump
• CPC Class Codes: F15B 11/006 Hydraulic "Wheatstone bridge" circuits, i.e. with four nodes, P-A-T-B, and on-off or proportional valves in each link
• CPC Class Codes: F15B 21/14 Energy-recuperation means
• CPC Class Codes: F15B 2211/20515 Electric motor
• CPC Class Codes: F15B 2211/20546 variable capacity
• CPC Class Codes: F15B 2211/26 Power control functions
• CPC Class Codes: F15B 2211/30575 in a Wheatstone Bridge arrangement (also half bridges)
• CPC Class Codes: F15B 2211/31576 having a single pressure source and a single output member
• CPC Class Codes: F15B 2211/327 electrically or electronically
• CPC Class Codes: F15B 2211/45 Control of bleed-off flow, e.g. control of bypass flow to the return line
• CPC Class Codes: F15B 2211/63 Electronic controllers
• CPC Class Codes: F15B 2211/6346 representing a state of input means, e.g. joystick position
• CPC Class Codes: F15B 2211/6651 Control of the prime mover, e.g. control of the output torque or rotational speed
• CPC Class Codes: F15B 2211/7053 Double-acting output members
• CPC Class Codes: F15B 2211/88 Control measures for saving energy

Abstract

A method and apparatus to improve regeneration efficiency when regenerating the energy of discharge fluid from a fluid pressure actuator as electrical energy. In a flow rate control line 15, which finctions as a discharge flow path for oil discharged from a head side oil chamber 1c of a hydraulic cylinder 1, is provided a displacement variable regenerating hydraulic motor 20, where controlling the displacement of the regenerating hydraulic motor 20 allows the flow rate of discharge oil from the hydraulic cylinder head side oil chamber 1c to be controlled. A generator 21, which generates electric power due to the rotation of the regenerating hydraulic motor 20, is further provided.

Claims

1. An energy regeneration system for working machinery comprising:

a fluid pressure actuator adapted to operate by supplying or discharging fluid;

a displacement variable regenerating fluid pressure motor disposed in a discharge flow path for fluid discharged from the fluid pressure actuator such that controlling the displacement of the regenerating fluid pressure motor allows the flow rate of discharge fluid from the fluid pressure actuator to be controlled; and

an energy regeneration device for regenerating the energy of discharge fluid as electrical energy at least in part by rotating the regenerating fluid pressure motor.

2. The energy regeneration system for working machinery according to claim 1, wherein the displacement of the regenerating fluid pressure motor is controlled so that the flow rate of discharge fluid from the fluid pressure actuator varies from zero to a predetermined maximum value.

3. The energy regeneration system for working machinery according to claim 2, wherein the flow rate of supply fluid to the fluid pressure actuator is controlled by a supplying flow rate control valve.

4. The energy regeneration system for working machinery according to claim 3, wherein the fluid pressure actuator is a single-rod fluid pressure cylinder, and the regenerating fluid pressure motor is provided in a discharge flow path for fluid discharged from a head side chamber of the fluid pressure cylinder.

5. The energy regeneration system for working machinery according to claim 4, further comprising a controller for receiving an input signal from a fluid pressure actuator operation tool and for outputting a control command to a displacement control means for the regenerating fluid pressure motor based on the input signal.

6. The energy regeneration system for working machinery according to claim 5, further comprising:

a pump adapted to supply pressurized fluid to the fluid pressure actuator; and

a motor operably coupled with the pump;

wherein electrical energy obtained by the energy regeneration device is used as a power supply source for the motor.

7. The energy regeneration system for working machinery according to claim 6, wherein the motor is used as an auxiliary power source for the pump.

8. The energy regeneration system for working machinery according to claim 7, wherein the energy regeneration device comprises:

a power generating means which generates electric power via the rotational driving of the regenerating fluid pressure motor;

a power storage means for storing electric power generated by the power generating means; and

an inverter for converting electric power stored in the power storage means into AC power.

9. A work machine comprising:

an engine;

a hydraulic system including a hydraulic pump, a hydraulic actuator coupled with said hydraulic pump and having first and second supply/discharge ports, and a discharge flow line from said hydraulic actuator;

a variable displacement hydraulic motor fluidly disposed between said first and second supply/discharge ports and exposed to a fluid pressure of said discharge flow line, said variable displacement hydraulic motor being configured to control a flow rate of discharge fluid from said hydraulic actuator; and

an energy regeneration device operably coupled with said variable displacement hydraulic motor and configured to supply power for operating at least one of said engine and said hydraulic pump.

10. The work machine of claim 9 further comprising an electric motor operably coupled with said energy regeneration device and with the at least one of said engine and said hydraulic pump.

11. The work machine of claim 10 wherein said hydraulic pump is operably coupled with said engine.

12. The work machine of claim 11 wherein said electric motor is operably coupled with said hydraulic pump.

13. The work machine of claim 10 wherein:

said hydraulic actuator comprises a linear hydraulic actuator having a rod supply/discharge port and a head supply/discharge port; and

said hydraulic system comprises a low pressure drain and first and second discharge flow lines connecting said rod supply/discharge port and said head supply/discharge port with said low pressure drain, respectively, said variable displacement hydraulic motor being exposed to a fluid pressure of said second discharge flow line between said head supply/discharge port and said low pressure drain.

14. The work machine of claim 13 further comprising a meter out valve disposed at least partially within said first discharge line, and an electronic controller in control communication with said variable displacement hydraulic motor and said meter out valve, said electronic controller being configured to output a displacement control command to a displacement control means of said variable displacement hydraulic motor responsively to the position of an operator input device.

15. The work machine of claim 14 wherein said electronic controller is configured to output a displacement zero command to said displacement control means of said variable displacement hydraulic motor responsively to an actuator extension command from said operator input device.

16. The work machine of claim 15 wherein said electronic controller is configured to output a nonzero displacement command to said displacement control means of said variable displacement hydraulic motor responsively to an actuator compression command from said operator input device corresponding with a position of an operator input device.

17. A method of operating a power system of a work machine comprising the steps of:

powering a hydraulic pump at least in part via an internal combustion engine of the work machine;

supplying hydraulic fluid to at least one hydraulic actuator of the work machine via the hydraulic pump;

powering an electrical generator of the work machine at least in part via a step of discharging hydraulic fluid through a hydraulic motor disposed at least partially within a fluid discharge line of the at least one hydraulic actuator; and

powering the hydraulic pump at least in part via electrical power from the electrical generator.

18. The method of claim 17 wherein the step of powering the hydraulic pump at least in part via electrical power comprises a step of assisting the engine in powering the hydraulic pump via an electric motor coupled with the electrical generator.

19. The method of claim 18 further comprising the step of storing energy generated by the electrical generator in a power storage system, wherein the step of powering the hydraulic pump at least in part via electrical power comprises powering the hydraulic pump via said power storage system.

20. The method of claim 19 wherein the hydraulic motor is a variable displacement hydraulic motor and the at least one hydraulic actuator comprises a linear hydraulic actuator, the method further comprising the step of, during powering of the electrical generator, transferring a selected volume of fluid between a head side chamber and a rod side chamber of the hydraulic actuator at least in part via a step of controlling a displacement of the hydraulic motor and a step of controlling a position of a meter out valve of the hydraulic actuator.