Energy recovery system

• US 7,634,911 B2
• Filed: 06/29/2007
• Issued: 12/22/2009
• Est. Priority Date: 06/29/2007
• Status: Expired due to Fees

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Brinkman, Jason L.
• Primary Examiner(s): LESLIE, MICHAEL S
• Application Number:
  US11/819,779
• Publication Number:
  US 20090000290A1
• Time in Patent Office: 907 Days
• Field of Search: 604/14, 914/37, 914/40, 914/50, 915/21, 915/33
• US Class Current: 60/414
• CPC Class Codes: E02F 9/2075 of the hybrid type for vehicles in general B60W20/00
• 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 11/024 by means of differential connection of the servomotor lines, e.g. regenerative circuits
• CPC Class Codes: F15B 21/14 Energy-recuperation means
• CPC Class Codes: F15B 2211/20523 Internal combustion engine
• CPC Class Codes: F15B 2211/20546 variable capacity
• CPC Class Codes: F15B 2211/3144 the positions being continuously variable, e.g. as realised by proportional valves
• CPC Class Codes: F15B 2211/625 Accumulators
• CPC Class Codes: F15B 2211/7053 Double-acting output members
• CPC Class Codes: F15B 2211/7128 the chambers being connected in parallel
• CPC Class Codes: F15B 2211/88 Control measures for saving energy

Abstract

An energy recovery system for a machine is disclosed. The energy recovery system may have a pump configured to provide a flow of pressurized fluid. The energy recovery system may also have a first fluid actuator with a first chamber and a second chamber and being configured to receive the pressurized fluid, a second fluid actuator with a third chamber and a fourth chamber and being configured to receive the pressurized fluid, and a first valve fluidly connected between the pump and the first and second actuators. The energy recovery system may additionally include an isolation unit with a first selectively restrictable passageway fluidly connecting the first chamber, the third chamber, and a first outlet of the first valve, and a second selectively restrictable passageway fluidly connecting the second chamber, the fourth chamber, and a second outlet of the first valve, as well as an energy recovery unit in fluid communication with the isolation unit. The isolation unit may be configured to direct a flow of pressurized fluid from the second actuator to the energy recovery unit. The energy recovery unit may be configured to convert the flow of pressurized fluid to a first mechanical power output.

Claims

1. An energy recovery system comprising:

a pump configured to provide pressurized fluid;

a first fluid actuator having a first chamber and a second chamber and being configured to receive the pressurized fluid;

a second fluid actuator having a third chamber and a fourth chamber and being configured to receive the pressurized fluid;

a first valve fluidly connected between the pump and the first and second actuators;

an isolation unit having a first selectively restrictable passageway fluidly connecting the first chamber, the third chamber, and a first outlet of the first valve, and a second selectively restrictable passageway fluidly connecting the second chamber, the fourth chamber, and a second outlet of the first valve; and

an energy recovery unit in fluid communication with the isolation unit,

wherein the isolation unit is configured to direct a flow of pressurized fluid from the second actuator to the energy recovery unit; and

the energy recovery unit is configured to convert the flow of pressurized fluid to a first mechanical power output.

2. The energy recovery system of claim 1, wherein the isolation unit is configured to direct the flow of pressurized fluid to the energy recovery unit when the first and second fluid actuators are operating in an overrunning load condition.

3. The energy recovery system of claim 1, wherein the isolation unit further includes:

a second valve located in the first selectively restrictable passageway and being configured to restrict fluid flow between the first and third chambers;

a third valve located in the second selectively restrictable passageway and being configured to restrict fluid flow between the second and fourth chambers;

a fourth valve located in a third passageway between the first and second chambers and being configured to allow unidirectional fluid flow from the second chamber to the first chamber; and

a fifth valve located in a fourth passageway between the third and fourth chambers and being configured to allow fluid flow between the third chamber and fourth chamber.

4. The energy recovery system of claim 3, wherein:

the flow of pressurized fluid is a first flow of pressurized fluid from the fourth chamber to the energy recovery unit; and

the isolation unit is further configured to;

direct pressurized fluid from the pump to the first chamber;

direct a second flow of pressurized fluid from the second chamber to the first chamber;

direct a third flow of pressurized fluid from the second chamber to the tank;

direct a fourth flow of pressurized fluid from the fourth chamber to the third chamber.

5. The energy recovery system of claim 4, wherein the first flow of pressurized fluid is about half of the fluid contained within the fourth chamber.

6. The energy recovery system of claim 1, wherein the energy recovery unit includes:

a sixth valve configured to fluidly connect the energy recovery unit to the isolation unit; and

a first motor configured to convert the flow of pressurized fluid to the first mechanical power output.

7. The energy recovery system of claim 6, wherein the energy recovery unit further includes:

an accumulator configured to store the flow of pressurized fluid from the isolation unit and to release the pressurized fluid to the first motor; and

a seventh valve configured to fluidly connect the accumulator to the energy recovery unit.

8. The energy recovery system of claim 6, wherein the energy recovery unit further includes:

a generator connected to the first motor and configured to convert the first mechanical power to an electrical power output;

an electric storage unit configured to store the electrical power from the generator; and

a second motor configured to convert the electrical power from the generator and the stored electrical power from the electric storage unit into a second mechanical power output.

9. A method of recovering energy from a hydraulic system, comprising:

pressurizing a fluid;

directing a first flow of the pressurized fluid to a first chamber of a first actuator to lower a load during an overrunning condition;

directing a second flow of the pressurized fluid from a first chamber of a second actuator connected to the load into a second chamber of the second actuator; and

generating a first mechanical power output from a third flow of the pressurized fluid from the first chamber of the second actuator, wherein the fluid in the first chamber of the first actuator and in the first chamber of the second actuator is pressurized by the load during the overrunning condition.

10. The method of claim 9, further including:

restricting a fluid exchange between the first and second actuators;

directing a fourth flow of pressurized fluid from a second chamber of the first actuator into the first chamber of the first actuator; and

directing a fifth flow of pressurized fluid from the second chamber of the first actuator to a reservoir.

11. The method of claim 10, further including;

directing the third flow of the pressurized fluid to an accumulator; and

generating the first mechanical power output from the pressurized fluid by providing the third flow of pressurized fluid to a first motor after the accumulator is full of pressurized fluid.

12. The method of claim 11, further including:

isolating the accumulator and the first motor from the first and second actuators; and

generating the first mechanical power output by providing pressurized fluid from the accumulator to the first motor.

13. The method of claim 9, wherein the third flow of the pressurized fluid is about half of the fluid contained within the first chamber of the second actuator.

14. The method of claim 9, further including:

generating an electrical output from the first mechanical power output;

storing the electrical output;

generating a second mechanical power output from the electrical output and the stored electrical output.

15. A machine, comprising:

a power source;

a tank configured to hold a supply of fluid;

a pump driven by the power source to draw fluid from the tank and pressurize the fluid;

a work tool;

a first fluid actuator having a first chamber and a second chamber and being configured to receive the pressurized fluid and move the work tool;

a second fluid actuator having a third chamber and a fourth chamber and being configured to receive the pressurized fluid and move the work tool in unison with the first fluid actuator;

a first valve fluidly connected between the pump and the first and second actuators;

an isolation unit fluidly connected between the first valve and the first and second actuators; and

an energy recovery unit in fluid communication with the isolation unit and being configured to convert a first flow of pressurized fluid to a first mechanical power output and input the first mechanical power output to the power source,

wherein the isolation unit is configured to;

selectively restrict fluid communication between the first actuator and the energy recovery unit;

selectively restrict fluid communication between the second actuator and the first valve; and

selectively direct the first flow of pressurized fluid to the energy recovery unit when the first and second fluid actuators are operating in an overrunning load condition.

16. The machine of claim 15, wherein the isolation unit includes:

a first passageway fluidly connecting the first chamber to the third chamber and to a first outlet of the first valve;

a second passageway fluidly connecting the second chamber to the fourth chamber and to a second outlet of the first valve;

a second valve configured to restrict fluid communication between the first and third chambers;

a third valve configured to restrict fluid communication between the second and fourth chambers;

a fourth valve configured to allow unidirectional fluid flow from the second chamber to the first chamber; and

a fifth valve configured to allow fluid communication between the third chamber and fourth chamber;

wherein the isolation unit is further configured to;

direct pressurized fluid from the pump to the first chamber;

direct a second flow of pressurized fluid from the second chamber to the first chamber;

direct a third flow of pressurized fluid from the second chamber to the tank;

direct a fourth flow of pressurized fluid from the fourth chamber to the third chamber; and

direct the first flow of pressurized fluid from the fourth chamber to the energy recovery unit when the first and second fluid actuators are operating in an overrunning load condition.

17. The machine of claim 16, wherein the first flow of pressurized fluid is about half of the fluid contained within the fourth chamber.

18. The machine of claim 15, wherein the energy recovery unit includes:

a sixth valve configured to fluidly connect the energy recovery unlit to the isolation unit; and

a first motor connected configured to convert the first flow of pressurized fluid to the first mechanical power output.

19. The machine of claim 18, wherein the energy recovery unit further includes:

an accumulator configured to store the pressurized fluid from the isolation unit and to release the pressurized fluid to the first motor; and

a seventh valve configured to fluidly connect the accumulator to the energy recovery unit;

wherein the first motor is further configured to transmit the first mechanical power output to the power source.

20. The machine of claim 18, wherein the energy recovery unit further includes:

a generator connected to the first motor and configured to convert the first mechanical power to an electrical power output;

an electric storage unit configured to store the electrical power from the generator; and

a second motor configured to;

convert the electrical power from the generator and the stored electrical power from the electric storage unit into a second mechanical power output; and

transmit the second mechanical power output to the power source.