Fluid circuit

Patent metadata

Field	Value
Publication number	US-11225983-B2
Application number	US-201917276918-A
Country	US
Kind code	B2
Filing date	Sep 25, 2019
Priority date	Sep 26, 2018
Publication date	Jan 18, 2022
Grant date	Jan 18, 2022

Abstract

A fluid circuit includes a pressure fluid source configured to supply pressure fluid, multiple actuators connected to the pressure fluid source, a direction switching valve configured to switch a supply destination of the pressure fluid supplied from the pressure fluid source, and a discharge amount control mechanism configured to control the output pressure of the pressure fluid source such that a pressure difference ΔP between the output pressure of the pressure fluid source and the maximum load pressure of the load pressures of the multiple actuators reaches a target value ΔPt. The fluid circuit further includes an accumulator configured to accumulate part of return fluid from the actuators.

First claim

The invention claimed is:

1. A fluid circuit including a pressure fluid source configured to supply pressure fluid, multiple actuators connected to the pressure fluid source, a direction switching valve configured to switch a supply destination of the pressure fluid supplied from the pressure fluid source, and a discharge amount control mechanism configured to control output pressure of the pressure fluid source such that a pressure difference between the output pressure of the pressure fluid source and a maximum load pressure of load pressures of the multiple actuators reaches a target value, comprising:
an accumulator configured to accumulate part of return fluid from the actuators,
wherein the accumulator is able to discharge the pressure fluid from the accumulator to a pressure-fluid-source-side flow path of the direction switching valve, and
pressure adjustment valve configured to adjust a control amount of the pressure fluid source based on a pressure of the accumulator is further provided.

2. The fluid circuit according to claim 1 , wherein
the control amount is adjusted by the pressure adjustment valve when the pressure fluid is discharged from the accumulator to the pressure-fluid-source-side flow path of the direction switching valve.

3. The fluid circuit according to claim 1 , further comprising:
a pressure sensor configured to detect the pressure of the accumulator; and
a control unit having an arithmetic circuit,
wherein the pressure adjustment valve is actuated by an electric signal output from the control unit based on the pressure detected by the pressure sensor.

4. The fluid circuit according to claim 1 , wherein
the discharge amount control mechanism includes a load sensing valve configured to adjust an opening degree of the load sensing valve based on a difference between pressure-fluid-source-side pressure and actuator-side pressure of the direction switching valve guided by a pilot pipe line, and
a pressure reduction valve as the pressure adjustment valve is provided at the pilot pipe line guiding the actuator-side pressure of the direction switching valve.

5. The fluid circuit according to claim 4 , wherein
a pressure reduction amount in the pressure reduction valve is adjusted based at least on the pressure-fluid-source-side pressure and the actuator-side pressure of the direction switching valve and the pressure of the accumulator.

6. The fluid circuit according to claim 2 , further comprising:
a pressure sensor configured to detect the pressure of the accumulator; and
a control unit having an arithmetic circuit,
wherein the pressure adjustment valve is actuated by an electric signal output from the control unit based on the pressure detected by the pressure sensor.

7. The fluid circuit according to claim 2 , wherein
the discharge amount control mechanism includes a load sensing valve configured to adjust an opening degree of the load sensing valve based on a difference between pressure-fluid-source-side pressure and actuator-side pressure of the direction switching valve guided by a pilot pipe line, and
a pressure reduction valve as the pressure adjustment valve is provided at the pilot pipe line guiding the actuator-side pressure of the direction switching valve.

8. The fluid circuit according to claim 7 , wherein
a pressure reduction amount in the pressure reduction valve is adjusted based at least on the pressure-fluid-source-side pressure and the actuator-side pressure of the direction switching valve and the pressure of the accumulator.

9. The fluid circuit according to claim 3 , wherein
the discharge amount control mechanism includes a load sensing valve configured to adjust an opening degree of the load sensing valve based on a difference between pressure-fluid-source-side pressure and actuator-side pressure of the direction switching valve guided by a pilot pipe line, and
a pressure reduction valve as the pressure adjustment valve is provided at the pilot pipe line guiding the actuator-side pressure of the direction switching valve.

10. The fluid circuit according to claim 9 , wherein
a pressure reduction amount in the pressure reduction valve is adjusted based at least on the pressure-fluid-source-side pressure and the actuator-side pressure of the direction switching valve and the pressure of the accumulator.

11. The fluid circuit according to claim 6 , wherein
the discharge amount control mechanism includes a load sensing valve configured to adjust an opening degree of the load sensing valve based on a difference between pressure-fluid-source-side pressure and actuator-side pressure of the direction switching valve guided by a pilot pipe line, and
a pressure reduction valve as the pressure adjustment valve is provided at the pilot pipe line guiding the actuator-side pressure of the direction switching valve.

12. The fluid circuit according to claim 11 , wherein
a pressure reduction amount in the pressure reduction valve is adjusted based at least on the pressure-fluid-source-side pressure and the actuator-side pressure of the direction switching valve and the pressure of the accumulator.

Assignees

• Eagle Ind Co Ltd

Inventors

• Shimada Yoshiyuki

Classifications

• F15B2211/20553

  with pilot circuit, e.g. for controlling a swash plate · CPC title

• F15B2211/20576

  with multiple pumps · CPC title

• E02F9/2232

  using one or more variable displacement pumps · CPC title

• F15B2211/6346

  representing a state of input means, e.g. joystick position · CPC title

• E02F9/2225

  using pressure-compensating valves · CPC title