Flow control for a hydraulic system

Patent metadata

Field	Value
Publication number	US-9567986-B2
Application number	US-201414491063-A
Country	US
Kind code	B2
Filing date	Sep 19, 2014
Priority date	Sep 19, 2014
Publication date	Feb 14, 2017
Grant date	Feb 14, 2017

Abstract

A hydraulic system associated with an engine may include a hydraulic pump, a hydraulic tank, a hydraulic starter and a second pump. The hydraulic system may include a relief valve that allows hydraulic fluid to pass through the relief valve when pressure at the relief valve meets a predetermined pressure. As well, the hydraulic system may include a first solenoid valve and a second solenoid valve. The first solenoid valve may be coupled between the hydraulic pump and the second pump to thereby control fluid flow to the second pump. Additionally, the second solenoid valve may be coupled between the hydraulic pump and the hydraulic starter to thereby control fluid flow to the hydraulic starter.

First claim

I claim:

1. A hydraulic system, comprising:
a first hydraulic pump;
a hydraulic tank coupled to the first hydraulic pump;
a second pump unit coupled to the first hydraulic pump via a supply line and the hydraulic tank via a return line, wherein the second pump unit is drivably operated based on pressurized fluid discharged from the first hydraulic pump;
a hydraulic starter coupled to the first hydraulic pump via the supply line and the hydraulic tank via the return line, wherein the hydraulic starter is drivably operated based on pressurized fluid discharged from the first hydraulic pump;
a first solenoid valve on the supply line coupled between the first hydraulic pump and the second pump, wherein the first solenoid valve is selectively movable between an open position and a closed position;
a second solenoid valve on the supply line coupled between the first hydraulic pump and the hydraulic starter, wherein the second solenoid valve is selectively movable between an open position and a closed position; and
a relief valve coupled between the supply line and the return line upstream of the first and second solenoid valves, wherein the relief valve is movable to an open position when hydraulic pressure in the supply line is greater than a predetermined pressure to thereby allow hydraulic fluid to move through the relief valve to the return line to the hydraulic tank.

2. The hydraulic system of claim 1 , further comprising a flow restriction coupled between the first solenoid valve and the second pump.

3. The hydraulic system of claim 2 , further comprising a pressure compensator coupled across the flow restriction.

4. The hydraulic system of claim 1 , further comprising a hydraulic line having a first end coupled between the second solenoid valve and the hydraulic starter, a second end coupled between the first solenoid valve and the second pump, and a third end coupled to the relief valve, wherein the relief valve is spring biased to the closed position via a spring force, and the predetermined pressure equals the spring force and pressure from the hydraulic line.

5. The hydraulic system of claim 4 , further comprising a shuttle valve coupled to the hydraulic line, wherein in response to the first end of the hydraulic line having a higher pressure than the second end of the hydraulic line, the shuttle valve communicates hydraulic fluid pressure from the first end of the hydraulic line to the relief valve, and wherein in response to the second end of the hydraulic line having a higher pressure than the first end of the hydraulic line, the shuttle valve communicates hydraulic fluid pressure from the second end of the hydraulic line to the relief valve.

6. The hydraulic system of claim 1 , further comprising an engagement valve coupled between the first solenoid valve and the hydraulic starter, wherein the engagement valve is configured to increase flow of hydraulic fluid to the hydraulic starter at a predetermined rate.

7. The hydraulic system of claim 1 , further comprising a first one-way valve coupled downstream from the hydraulic starter and upstream from the hydraulic tank.

8. The hydraulic system of claim 7 , further comprising a second one-way valve coupled downstream from the second pump and upstream from the hydraulic tank.

9. The hydraulic system of claim 1 , wherein when the first solenoid valve is in the closed position, the second solenoid valve is in the open position, and wherein when the second solenoid valve is in the closed position, the first solenoid valve is in the open position.

10. A valve assembly, comprising:
a first port configured to be hydraulically coupled to a first hydraulic pump;
a second port configured to be hydraulically coupled to a hydraulic tank;
a third port and a fourth port configured each to be hydraulically coupled to corresponding ends of a hydraulic starter;
a fifth port and a sixth port configured to be hydraulically coupled to corresponding ends of a second pump;
a relief valve hydraulically coupled between the first port and the second port, wherein the relief valve is configured to open when hydraulic pressure is greater than a predetermined pressure to thereby allow hydraulic fluid to move through the relief valve to the second port, and wherein the relief valve is configured to close when the hydraulic pressure is less than the predetermined pressure to prevent hydraulic fluid from moving through the relief valve to the second port;
a first solenoid valve hydraulically coupled between the first port and the fifth port, wherein the first solenoid valve is movable between an open position and a closed position, wherein when the first solenoid valve is in the open position, hydraulic fluid is allowed to move from the first port to the fifth port, and wherein when the first solenoid valve is in the closed position, hydraulic fluid is prevented from moving from the first port to the fifth port; and
a second solenoid valve hydraulically coupled between the first port and the third port, wherein the second solenoid valve is movable between an open position and a closed position, wherein when the second solenoid valve is in the open position, hydraulic fluid is allowed to move from the first port to the third port, and wherein when the second solenoid valve is in the closed position, hydraulic fluid is prevented from moving from the first port to the third port.

11. The valve assembly of claim 10 , wherein the fourth port is hydraulically coupled to the second port, and the sixth port is hydraulically coupled to the second port, the valve assembly further comprising a flow restriction coupled between the first solenoid valve and the fifth port.

12. The valve assembly of claim 11 , further comprising a pressure compensator coupled across the flow restriction.

13. The valve assembly of claim 10 , further comprising a hydraulic line having a first end coupled between the first solenoid valve and the fifth port, a second end coupled between the second solenoid valve and the third port, and a third end coupled to the relief valve, wherein the relief valve is spring biased to the closed position via a spring force, and the predetermined pressure equals the spring force and pressure from the hydraulic line.

14. The valve assembly of claim 13 , further comprising a shuttle valve coupled to the hydraulic line, wherein the shuttle valve allows hydraulic fluid to flow from the first solenoid valve to the relief valve, or from the second solenoid valve to the relief valve.

15. The valve assembly of claim 10 , further comprising:
a first one-way valve coupled downstream from the fourth port and upstream from the third port; and
a second one-way valve coupled downstream from the sixth port and upstream from the fifth port.

16. The valve assembly of claim 10 , further comprising:
a first gauge port hydraulically coupled to the first port, wherein the first gauge port is configured to indicate pressure at the first hydraulic pump;
a second gauge port hydraulically coupled to the second port, wherein the second gauge port is configured to indicate pressure at the hydraulic tank;
a third gauge port hydraulically coupled to the third port, wherein the third gauge port is configured to indicate pressure at the hydraulic starter; and
a fourth gauge port hydraulically coupled to the fifth port, wherein the fourth gauge port is configured to indicate pressure at the second pump.

17. A method of operating a hydraulic system, comprising:
pressurizing hydraulic fluid via a first hydraulic pump that is coupled to a hydraulic tank;
moving a first s

Assignees

• Caterpillar Inc

Inventors

• Perry Toby

Classifications

• F02N15/06

  the toothed gears being moved by axial displacement · CPC title

• F04B23/04

  Combinations of two or more pumps · CPC title

• F04B49/22

  by means of valves (F04B49/03 takes precedence) · CPC title

• F04B23/06

  the pumps being all of reciprocating positive-displacement type · CPC title

• F04B49/06

  Control using electricity (regulating by means of floats actuating electric switches F04B49/04) · CPC title