Hydraulic system and work machine

Patent metadata

Field	Value
Publication number	US-9902384-B2
Application number	US-201615194574-A
Country	US
Kind code	B2
Filing date	Jun 28, 2016
Priority date	Mar 31, 2014
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

A hydraulic system includes a motor. A brake is to be actuated by an operation fluid to brake the motor when a hydraulic pressure is relieved and to release the braking when the hydraulic pressure is applied. A switch valve is to be switched to a first position and to a second position, the first position being provided for relieving the hydraulic pressure from the brake, the second position being provided for applying the hydraulic pressure to the brake. A first fluid tube is to connect the switch valve and the brake. A second fluid tube is connected to the first fluid tube at a connecting portion and communicated with a tank A first throttle is disposed on the second fluid tube. A second throttle is disposed on the first fluid tube and on an upstream side between the connecting portion and the switch valve.

First claim

What is claimed is:

1. A hydraulic system comprising:
a motor;
a brake to be actuated by an operation fluid to brake the motor when a hydraulic pressure is relieved and to release the braking when the hydraulic pressure is applied;
a switch valve to be switched to a first position and to a second position, the first position being provided for relieving the hydraulic pressure from the brake, the second position being provided for applying the hydraulic pressure to the brake;
a first fluid tube to connect the switch valve and the brake;
a second fluid tube connected to the first fluid tube at a connecting portion and communicated with a tank;
a first throttle disposed on the second fluid tube; and
a second throttle disposed on the first fluid tube and on an upstream side between the connecting portion and the switch valve.

2. The hydraulic system according to claim 1 , wherein
the second throttle is disposed near the connecting portion.

3. The hydraulic system according to claim 2 , wherein
a throttle aperture of the second throttle is larger than a throttle aperture of the first throttle.

4. The hydraulic system according to claim 2 , wherein
a throttle aperture of the second throttle is equal to a throttle aperture of the first throttle.

5. The hydraulic system according to claim 1 , wherein
a throttle aperture of the second throttle is larger than a throttle aperture of the first throttle.

6. The hydraulic system according to claim 1 , wherein
a throttle aperture of the second throttle is equal to a throttle aperture of the first throttle.

7. A work machine comprising:
a motor;
a drive device to be driven by the motor;
a brake to be actuated by an operation fluid to brake the motor when a hydraulic pressure is relieved and to release the braking when the hydraulic pressure is applied;
a switch valve to be switched to a first position and to a second position, the first position being provided for relieving the hydraulic pressure from the brake, the second position being provided for applying the hydraulic pressure to the brake;
a first fluid tube to connect the switch valve and the brake;
a second fluid tube connected to the first fluid tube at a connecting portion and communicated with a tank;
a first throttle disposed on the second fluid tube; and
a second throttle disposed on the first fluid tube and on an upstream side between the connecting portion and the switch valve.

8. The work machine according to claim 7 , wherein
the second throttle is disposed near the connecting portion.

9. The work machine according to claim 8 , wherein
a throttle aperture of the second throttle is larger than a throttle aperture of the first throttle.

10. The work machine according to claim 8 , wherein
a throttle aperture of the second throttle is equal to a throttle aperture of the first throttle.

11. The work machine according to claim 7 , wherein
a throttle aperture of the second throttle is larger than a throttle aperture of the first throttle.

12. The work machine according to claim 7 , wherein
a throttle aperture of the second throttle is equal to a throttle aperture of the first throttle.

13. The work machine according to claim 7 , comprising
a machine body, wherein
the drive device is disposed on the machine body.

14. The work machine according to claim 13 , comprising:
an engine;
a hydraulic pump to be driven by the engine; and
a hydrostatic continuously variable transmission to drive the drive device, the hydrostatic continuously variable transmission including the motor and a hydraulic pump.

15. A hydraulic system comprising:
a motor;
a brake to be actuated by an operation fluid to brake the motor when a hydraulic pressure is relieved and to release the braking when the hydraulic pressure is applied;
a switch valve to switch between a first flowing path through which the hydraulic pressure is relieved from the brake and a second flowing path through which the hydraulic pressure is applied to the brake;
a first fluid tube to connect the switch valve and the brake;
a second fluid tube connected to the first fluid tube at a connecting portion and communicated with a tank;
a first throttle disposed on the second fluid tube; and
a second throttle disposed on the first fluid tube and on an upstream side between the connecting portion and the switch valve.

16. The hydraulic system according to claim 15 , wherein
the second throttle is disposed near the connecting portion.

17. The hydraulic system according to claim 16 , wherein
a throttle aperture of the second throttle is larger than a throttle aperture of the first throttle.

18. The hydraulic system according to claim 16 , wherein
a throttle aperture of the second throttle is equal to a throttle aperture of the first throttle.

19. The hydraulic system according to claim 15 , wherein
a throttle aperture of the second throttle is larger than a throttle aperture of the first throttle.

20. The hydraulic system according to claim 15 , wherein
a throttle aperture of the second throttle is equal to a throttle aperture of the first throttle.

Assignees

• Kubota Kk

Inventors

• Fukuda Yuji
• Arii Kazuyoshi

Classifications

• F16H61/40

  hydrostatic · CPC title

• E02F9/2267

  Valves or distributors (position of valves arrangements on upper-structures E02F9/0875) · CPC title

• F16D1/00

  Couplings for rigidly connecting two coaxial shafts or other movable machine elements (attachment of wheels to axles for railway carriages B60B; for attachment of cranks to their shafts F16C3/10) · CPC title

• B60T1/12

  acting otherwise than by retarding wheels, e.g. jet action · CPC title

• E02F9/2296

  Systems with a variable displacement pump · CPC title