WORK MACHINE AND HYDRAULIC SYSTEM FOR WORK MACHINE

• US 20170159265A1
• Filed: 12/06/2016
• Published: 06/08/2017
• Est. Priority Date: 12/07/2015
• Status: Active Grant

• Current Assignee: Kubota Corporation
• Original Assignee: Kubota Corporation
• Inventors: FUKUDA, Yuji, TOMITA, Jun, KONISHI, Yuya
• Granted Patent: US 10,316,489 B2
• Time in Patent Office: Days
• CPC Class Codes: E02F 3/3414 the arms being pivoted at the rear of the vehicle chassis, e.g. skid steer loader
• CPC Class Codes: E02F 3/422 Drive systems for bucket-arms, front-end loaders, dumpers or the like
• CPC Class Codes: E02F 3/432 for keeping the bucket in a predetermined position or attitude
• CPC Class Codes: E02F 9/2203 Arrangements for controlling the attitude of actuators, e.g. speed, floating function
• CPC Class Codes: E02F 9/2217 with energy recovery arrangements, e.g. using accumulators, flywheels
• CPC Class Codes: E02F 9/2267 Valves or distributors position of valves arrangements on upper-structures E02F9/0875
• CPC Class Codes: E02F 9/2282 Systems using center bypass type changeover valves
• CPC Class Codes: F15B 1/021 used for damping
• 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 2211/3059 having multiple valves for multiple output members
• CPC Class Codes: F15B 2211/30595 with additional valves between the groups of valves for multiple output members
• CPC Class Codes: F15B 2211/625 Accumulators
• CPC Class Codes: F15B 2211/6658 Control using different modes, e.g. four-quadrant-operation, working mode and transportation mode
• CPC Class Codes: F15B 2211/71 Multiple output members, e.g. multiple hydraulic motors or cylinders

Abstract

A hydraulic system for a work machine includes a first control valve to control a first hydraulic actuator, a second control valve to control a second hydraulic actuator, a first fluid tube connecting the first hydraulic actuator to the first control valve, and a second fluid tube connecting the second hydraulic actuator to the second control valve. A level control valve apparatus is connected to the first fluid tube and the second fluid tube. The level control valve apparatus is configured to control a leveling operation for the second hydraulic actuator. An accumulator apparatus is connected to the first hydraulic actuator. The accumulator apparatus communicates with the first fluid tube between the level control valve apparatus and the first control valve. Circuitry is configured to control the level control valve apparatus to stop the leveling operation when the accumulator apparatus is in operation.

Claims

1. A hydraulic system for a work machine, comprising:

a first hydraulic actuator;

a second hydraulic actuator other than the first hydraulic actuator;

a first control valve to control the first hydraulic actuator;

a second control valve to control the second hydraulic actuator;

a first fluid tube connecting the first hydraulic actuator to the first control valve;

a second fluid tube connecting the second hydraulic actuator to the second control valve;

a level control valve apparatus connected to the first fluid tube and the second fluid tube, the level control valve apparatus being configured to control a leveling operation for the second hydraulic actuator;

an accumulator apparatus connected to the first hydraulic actuator, the accumulator apparatus communicating with the first fluid tube between the level control valve apparatus and the first control valve; and

circuitry configured to control the level control valve apparatus to stop the leveling operation when the accumulator apparatus is in operation.

2. The hydraulic system for the work machine, according to claim 1, wherein

the level control valve apparatus includes

an operation device configured to switch an operational state between a first state to stop the leveling operation and a second state to activate the leveling operation, and

the controller switches the operation device to the first state to stop the leveling operation when the accumulator apparatus is in operation.

3. The hydraulic system for the wok machine, according to claim 2, wherein

the first hydraulic actuator is a boom cylinder,

the second hydraulic actuator is a bucket cylinder, and

the controller switches the operation device to the second state to activate the leveling operation when the boom cylinder is stretched.

9. The hydraulic system for the work machine according to claim 1, wherein

the level control valve apparatus includes

a switch valve configured to be switched to

a first position such that, in the first fluid tube, an operation fluid returns from the first hydraulic actuator to the first control valve and flows from the first control valve to the first hydraulic actuator,

a second position such that the flow of the operation fluid returning in the first fluid tube from the first hydraulic actuator to the first control valve is blocked.

13. The hydraulic system for the work machine, according to claim 9, wherein

the level control valve apparatus includes

a flow tube connecting the first fluid tube to the second fluid tube, the operation fluid being supplied to the second hydraulic actuator through the flow tube when the switch valve is at the second position, the operation fluid returning from the first hydraulic actuator to the first control valve.

17. The hydraulic system for the work machine, according to claim 1, wherein

the first fluid tube includes:

a first supply tube connected to a bottom side of a first hydraulic cylinder constituting the first hydraulic actuator; and

a second supply tube connected to a rod side of the first hydraulic cylinder, and

the second fluid tube includes;

a third supply tube connected to a rod side of a second hydraulic cylinder constituting the second hydraulic actuator; and

a fourth supply tube connected to a bottom side of the second hydraulic cylinder.

4. A hydraulic system for a work machine, comprising:

a first hydraulic actuator;

a second hydraulic actuator other than the first hydraulic actuator;

a first control valve to control the first hydraulic actuator;

a second control valve to control the second hydraulic actuator;

a first fluid tube connecting the first hydraulic actuator to the first control valve;

a second fluid tube connecting the second hydraulic actuator to the second control valve;

a level control valve apparatus connected to the first fluid tube and the second fluid tube, the level control valve apparatus being configured to control a leveling operation for the second hydraulic actuator;

an accumulator apparatus connected to the first hydraulic actuator; and

a third fluid tube having a first tube end connected to the first hydraulic actuator and a second tube end which is opposite to the first tube end and which is connected to the first fluid tube between the level control valve apparatus and the first control valve.

5. The hydraulic system for the work machine, according to claim 4, comprising

a discharge fluid tube connected to the accumulator apparatus, the discharge fluid tube being configured to discharge an operation fluid supplied from the accumulator apparatus, wherein

the accumulator apparatus includes:

an accumulator; and

a ride control valve configured to connect the third fluid tube, the first hydraulic actuator, the accumulator, and the discharge fluid tube to each other, and

the ride control valve is configured to be switched to

a stopping position to block the connection between the first hydraulic actuator and the accumulator and to block the connection between the third hydraulic tube and the discharge fluid tube and

an activating position to connect the first hydraulic actuator to the accumulator and to connect the third hydraulic tube and the discharge fluid tube.

10. The hydraulic system for the work machine, according to claim 4, wherein

the level control valve apparatus includes

a switch valve configured to be switched to

a first position such that, in the first fluid tube, an operation fluid returns from the first hydraulic actuator to the first control valve and flows from the first control valve to the first hydraulic actuator, and

a second position such that the flow of the operation fluid returning in the first fluid tube from the first hydraulic actuator to the first control valve is blocked.

14. The hydraulic system for the work machine, according to claim 10, wherein

the level control valve apparatus includes

a flow tube connecting the first fluid tube to the second fluid tube, the operation fluid being supplied to the second hydraulic actuator through the flow tube when the switch valve is at the second position, the operation fluid returning from the first hydraulic actuator to the first control valve.

18. The hydraulic system for the work machine, according to claim 4, wherein

the first fluid tube includes:

a first supply tube connected to a bottom side of a first hydraulic cylinder constituting the first hydraulic actuator; and

a second supply tube connected to a rod side of the first hydraulic cylinder, and

the second fluid tube includes;

a third supply tube connected to a rod side of a second hydraulic cylinder constituting the second hydraulic actuator; and

a fourth supply tube connected to a bottom side of the second hydraulic cylinder.

6. A hydraulic system for a work machine, comprising:

a first hydraulic actuator;

a second hydraulic actuator other than the first hydraulic actuator;

a first control valve to control the first hydraulic actuator;

a second control valve to control the second hydraulic actuator;

a first fluid tube connecting the first hydraulic actuator to the first control valve;

a second fluid tube connecting the second hydraulic actuator to the second control valve;

a level control valve apparatus connected to the first fluid tube and the second fluid tube, the level control valve apparatus being configured to control a leveling operation for the second hydraulic actuator;

an accumulator apparatus connected to the first hydraulic actuator and configured to provide an anti-vibration operation to suppress fluctuation of a pressure of the first hydraulic actuator, the accumulator apparatus being configured to switch an operational state between a stopping state to stop the anti-vibration operation, a first operational state to activate both of the leveling operation and the anti-vibration operation, and a second operational state to activate the anti-vibration operation.

11. The hydraulic system for the work machine, according to claim 6, wherein

the level control valve apparatus includes

a switch valve configured to be switched to

a first position such that, in the first fluid tube, an operation fluid returns from the first hydraulic actuator to the first control valve and flows from the first control valve to the first hydraulic actuator, and

a second position such that the flow of the operation fluid returning in the first fluid tube from the first hydraulic actuator to the first control valve is blocked.

15. The hydraulic system for the work machine, according to claim 11, wherein

the level control valve apparatus includes

a flow tube connecting the first fluid tube to the second fluid tube, the operation fluid being supplied to the second hydraulic actuator through the flow tube when the switch valve is at the second position, the operation fluid returning from the first hydraulic actuator to the first control valve.

19. The hydraulic system for the work machine, according to claim 6, wherein

the first fluid tube includes:

a first supply tube connected to a bottom side of a first hydraulic cylinder constituting the first hydraulic actuator; and

a second supply tube connected to a rod side of the first hydraulic cylinder, and

the second fluid tube includes;

a third supply tube connected to a rod side of a second hydraulic cylinder constituting the second hydraulic actuator; and

a fourth supply tube connected to a bottom side of the second hydraulic cylinder.

7. A hydraulic system for a work machine, comprising:

a first hydraulic actuator having;

a first fluid chamber; and

a second fluid chamber;

a second hydraulic actuator other than the first hydraulic actuator;

a first control valve to control the first hydraulic actuator;

a second control valve to control the second hydraulic actuator;

a first fluid tube connecting the first hydraulic actuator to the first control valve;

a second fluid tube connecting the second hydraulic actuator to the second control valve;

a level control valve apparatus connected to the first fluid tube and the second fluid tube, the level control valve apparatus being configured to control a leveling operation for the second hydraulic actuator;

an accumulator apparatus connected to the first hydraulic actuator and configured to provide an anti-vibration operation to suppress fluctuation of a pressure of the first hydraulic actuator; and

a discharge fluid tube connected to the accumulator apparatus, the discharge fluid tube being configured to discharge an operation fluid supplied from the accumulator apparatus, wherein

the accumulator apparatus includes;

an accumulator; and

a ride control valve configured to be switched to;

a stopping position to block a connection between the accumulator and the first fluid chamber of the first hydraulic actuator and to block a connection between the discharge fluid tube and the second fluid chamber of the first hydraulic actuator;

a first activating position to connect the first fluid chamber to the accumulator and to block the connection between the second fluid chamber and the discharge fluid tube, and thus to activate both of the leveling operation and the anti-vibration operation; and

a second activating position to connect the first fluid chamber to the accumulator and to connect the second fluid chamber to the discharge fluid tube, and thus to activate the anti-vibration operation.

12. The hydraulic system for the work machine, according to claim 7, wherein

the level control valve apparatus includes

a switch valve configured to be switched to

a first position such that, in the first fluid tube, an operation fluid returns from the first hydraulic actuator to the first control valve and flows from the first control valve to the first hydraulic actuator, and

a second position such that the flow of the operation fluid returning in the first fluid tube from the first hydraulic actuator to the first control valve is blocked.

16. The hydraulic system for the work machine, according to claim 12, wherein

the level control valve apparatus includes

a flow tube connecting the first fluid tube to the second fluid tube, the operation fluid being supplied to the second hydraulic actuator through the flow tube when the switch valve is at the second position, the operation fluid returning from the first hydraulic actuator to the first control valve.

20. The hydraulic system for the work machine, according to claim 7, wherein

the first fluid tube includes:

a first supply tube connected to a bottom side of a first hydraulic cylinder constituting the first hydraulic actuator; and

a second supply tube connected to a rod side of the first hydraulic cylinder, and

the second fluid tube includes;

a third supply tube connected to a rod side of a second hydraulic cylinder constituting the second hydraulic actuator; and

a fourth supply tube connected to a bottom side of the second hydraulic cylinder.

8. A hydraulic system for a work machine, comprising:

a first hydraulic actuator;

a second hydraulic actuator other than the first hydraulic actuator; and

an accumulator apparatus connected to the first hydraulic actuator and configured to provide an anti-vibration operation to suppress fluctuation of a pressure of the first hydraulic actuator, the accumulator apparatus being configured to be switched to;

a stopping state to stop the anti-vibration operation;

a first activating state to activate both of the second hydraulic actuator and the anti-vibration operation; and

a second activating state to activate the anti-vibration operation.