Meterless hydraulic system having multi-actuator circuit

• US 9,051,714 B2
• Filed: 09/30/2011
• Issued: 06/09/2015
• Est. Priority Date: 09/30/2011
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Opdenbosch, Patrick
• Primary Examiner(s): LESLIE, MICHAEL S
• Application Number:
  US13/250,067
• Publication Number:
  US 20130081704A1
• Time in Patent Office: 1,348 Days
• Field of Search: 604/13, 604/14, 604/20, 604/45, 604/59, 604/73, 604/75, 604/76, 604/84
• US Class Current: 1/1
• CPC Class Codes: E02F 9/2217 with energy recovery arrangements, e.g. using accumulators, flywheels
• CPC Class Codes: E02F 9/2235 including an electronic controller
• CPC Class Codes: E02F 9/2285 Pilot-operated systems
• CPC Class Codes: E02F 9/2289 Closed circuit
• CPC Class Codes: E02F 9/2296 Systems with a variable displacement pump
• CPC Class Codes: F15B 11/036 by means of servomotors having a plurality of working chambers
• CPC Class Codes: F15B 11/0423 by controlling pump output or bypass, other than to maintain constant speed
• CPC Class Codes: F15B 15/221 for accelerating the stroke, e.g. by area increase
• CPC Class Codes: F15B 2211/20546 variable capacity
• CPC Class Codes: F15B 2211/20561 reversible
• CPC Class Codes: F15B 2211/20569 capable of working as pump and motor
• CPC Class Codes: F15B 2211/212 the pressure sources being accumulators
• CPC Class Codes: F15B 2211/27 Directional control by means of the pressure source
• CPC Class Codes: F15B 2211/30515 Load holding valves
• CPC Class Codes: F15B 2211/30565 having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve
• CPC Class Codes: F15B 2211/30595 with additional valves between the groups of valves for multiple output members
• CPC Class Codes: F15B 2211/31529 having a single pressure source and a single output member
• CPC Class Codes: F15B 2211/31541 having a single pressure source and multiple output members
• CPC Class Codes: F15B 2211/40592 with multiple valves in parallel flow paths,
• CPC Class Codes: F15B 2211/41563 being connected to a pressure source and a return line
• CPC Class Codes: F15B 2211/50527 : using cross-pressure relief valves
• CPC Class Codes: F15B 2211/613 : Feeding circuits
• CPC Class Codes: F15B 2211/625 : Accumulators
• CPC Class Codes: F15B 2211/6346 : representing a state of input means, e.g. joystick position
• CPC Class Codes: F15B 2211/6654 : Flow rate control
• CPC Class Codes: F15B 2211/7055 : having more than two chambers
• CPC Class Codes: F15B 2211/7128 : the chambers being connected in parallel
• CPC Class Codes: F15B 2211/7135 : Combinations of output members of different types, e.g. single-acting cylinders with rotary motors
• CPC Class Codes: F15B 2211/7142 : the output members being arranged in multiple groups
• CPC Class Codes: F15B 2211/761 : Control of a negative load, i.e. of a load generating hydraulic energy
• CPC Class Codes: F15B 2211/763 : Control of torque of the output member by means of a variable capacity motor, i.e. by a secondary control on the motor
• CPC Class Codes: F15B 2211/785 : Compensation of the difference in flow rate in closed fluid circuits using differential actuators
• CPC Class Codes: F15B 2211/88 : Control measures for saving energy
• CPC Class Codes: F15B 7/006 : Rotary pump input
• CPC Class Codes: Y10T 137/0396 : Involving pressure control
• CPC Class Codes: Y10T 137/85954 : Closed circulating system

Abstract

A hydraulic system is disclosed. The hydraulic system may have a pump, a first actuator, and a meterless circuit connecting the first actuator to the pump. The hydraulic system may also have a second actuator connected to the meterless circuit in parallel with the first actuator. The second actuator may be a variable-area linear actuator.

Claims

1. A hydraulic system, comprising:

a pump;

a first actuator, wherein the first actuator is a fixed-area linear actuator;

a meterless circuit connecting the first actuator to the pump;

a second actuator connected to the meterless circuit in parallel with the first actuator, the second actuator being a variable-area linear actuator;

a rotary actuator connected to the meterless circuit in parallel with the first and second actuators; and

at least a first switching valve associated with the rotary actuator and configured to switch a flow direction of fluid passing through the rotary actuator.

2. The hydraulic system of claim 1, wherein the pump is an over-center, variable-displacement pump.

3. The hydraulic system of claim 1, further including at least a second switching valve associated with the second actuator and configured to switch a flow direction of fluid passing into the second actuator.

4. The hydraulic system of claim 3, further including at least a third switching valve associated with the first actuator and configured to switch a flow direction of fluid passing into the first actuator.

5. The hydraulic system of claim 3, further including a combiner valve disposed between the pump and the second actuator, the combiner valve configured to selectively communicate the pump with the second actuator.

6. The hydraulic system of claim 1, further including at least one isolation valve configured to selectively isolate a suction side of the pump from the meterless circuit.

7. The hydraulic system of claim 6, further including a charge circuit in selective fluid communication with the meterless circuit.

8. The hydraulic system of claim 7, further including:

at least one relief valve disposed between the meterless circuit and the charge circuit; and

at least one makeup valve disposed between the charge circuit and the meterless circuit.

9. The hydraulic system of claim 1, further including:

an accumulator; and

an accumulator valve configured to selectively communicate the accumulator with the meterless circuit.

10. The hydraulic system of claim 1, wherein the meterless circuit is a closed-loop circuit.

11. A hydraulic system, comprising:

an over-center, variable-displacement pump;

a fixed-area linear actuator;

a meterless circuit connecting the fixed-area linear actuator to the pump, wherein operation of the fixed-area linear actuator is controlled via regulation of the pump;

a variable-area linear actuator connected to the meterless circuit in parallel with the fixed-area linear actuator;

a rotary actuator connected to the meterless circuit in parallel with the first and second actuators; and

at least a first switching valve associated with the rotary actuator and configured to switch a flow direction of fluid passing through the rotary actuator.

12. The hydraulic system of claim 11, further including a variable displacement rotary actuator connected to the meterless circuit in parallel with the fixed- and variable area actuators.

13. A method of operating a hydraulic system, comprising:

pressurizing fluid with a pump;

directing fluid pressurized by the pump to a first linear actuator and returning fluid from the first linear actuator to the pump via a meterless circuit;

adjusting operation of the pump to adjust operation of the first linear actuator;

directing fluid pressurized by the pump to a second linear actuator and returning fluid from the second linear actuator to the pump via the meterless circuit;

adjusting a pressure area of the second linear actuator to adjust operation of the second actuator;

at least partially isolating a suction side of the pump from the meterless circuit;

selectively storing fluid discharged from the first or second linear actuators while the suction side of the pump is at least partially isolated from the meterless circuit; and

providing makeup fluid to the meterless circuit during the selective storing of fluid.

14. The method of claim 13, further including adjusting a displacement position of the pump to switch a movement direction of the first linear actuator.

15. The method of claim 13, further including directing fluid pressurized by the pump to a rotary actuator and returning fluid from the rotary actuator to the pump via the meterless circuit.