Pressure and flow compensated hydraulic system

Patent metadata

Field	Value
Publication number	US-9671009-B2
Application number	US-201414520420-A
Country	US
Kind code	B2
Filing date	Oct 22, 2014
Priority date	Oct 22, 2014
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

Abstract

A vehicle hydraulic system includes a transmission lube circuit, a variable displacement main pump having an inlet, and a variable displacement charge pump having an outlet and a pressure responsive displacement control unit. The system also includes a charge line communicating the charge pump outlet with the main pump inlet, a sensing line communicating the charge line with the displacement control unit, and a lube line communicating the charge pump outlet with the lube circuit. The lube line includes a fluid restriction. A hydraulic oil filter and a filter bypass valve are connected in parallel between the outlet of the charge pump and the charge line.

First claim

What is claimed is:

1. A vehicle hydraulic system comprising:
a transmission lube circuit;
a main pump;
a variable displacement charge pump for supplying charge fluid to the main pump, the charge pump having an outlet and having a pressure responsive displacement control unit;
a charge line communicating the variable displacement charge pump outlet with an inlet of the main pump;
a sensing line connecting and communicating the charge line with the pressure responsive displacement control unit;
a lube line connecting and communicating the charge pump outlet with the lube circuit; and
a fluid restriction in the lube line, wherein the fluid restriction limits the amount of fluid into the transmission lube circuit and maintains a pressure at the inlet of the main pump.

2. The vehicle hydraulic system of claim 1 , wherein:
the main pump is a variable displacement pump.

3. The vehicle hydraulic system of claim 1 , further comprising:
a transmission pump having an inlet connected to the charge line and having an outlet connected to a transmission control circuit.

4. The vehicle hydraulic system of claim 3 , wherein:
the transmission pump is a fixed displacement pump.

5. The vehicle hydraulic system of claim 1 , further comprising:
a hydraulic oil filter connected between the outlet of the variable displacement charge pump and the charge line; and
a filter bypass valve connected between the outlet of the charge pump and the charge line.

6. The vehicle hydraulic system of claim 1 , further comprising:
a brake valve reservoir supply line connected between the charge line and a brake valve; and
a further fluid restriction in the brake line.

7. The vehicle hydraulic system of claim 1 , wherein the vehicle hydraulic system is without a dedicated fixed displacement transmission lube pump.

8. The vehicle hydraulic system of claim 1 , wherein the variable displacement charge pump supplies lube fluid to the transmission lube circuit.

9. The vehicle hydraulic system of claim 1 , wherein the fluid restriction maintains a required minimum pressure at the inlet of the main pump.

10. A vehicle hydraulic system comprising:
a transmission lube circuit;
a variable displacement main pump having an inlet;
a variable displacement charge pump for supplying charge fluid to the main pump inlet, the variable displacement charge pump having an outlet and having a pressure responsive displacement control unit;
a charge line communicating the variable displacement charge pump outlet with the main pump inlet;
a sensing line connecting and communicating the charge line with the pressure responsive displacement control unit;
a lube line connecting and communicating the charge pump outlet with the lube circuit;
a fluid restriction in the lube line, wherein the fluid restriction limits fluid flow to the transmission lube circuit and maintains a pressure at the inlet of the main pump;
a hydraulic oil filter connected between the outlet of the variable displacement charge pump and the charge line; and
a filter bypass valve connected between the outlet of the variable displacement charge pump and the charge line.

11. The vehicle hydraulic system of claim 10 , further comprising:
a fixed displacement transmission pump having an inlet connected to the charge line and having an outlet connected to a transmission control circuit.

12. The vehicle hydraulic system of claim 10 , wherein the vehicle hydraulic system is without a dedicated fixed displacement transmission lube pump.

13. The vehicle hydraulic system of claim 10 , wherein the variable displacement charge pump supplies lube fluid to the transmission lube circuit.

14. The vehicle hydraulic system of claim 10 , wherein the fluid restriction maintains a required minimum pressure at the inlet of the main pump.

Assignees

• Deere & Co

Inventors

• Nystrom Dwayne A
• Knight Jesse R
• Holland Michael A

Classifications

• F16H2061/0037

  characterised by controlled fluid supply to lubrication circuits of the gearing · CPC title

• F16H57/0404

  Lubricant filters · CPC title

• F16H57/0435 Primary

  Pressure control for supplying lubricant; Circuits or valves therefor · CPC title

• F16H61/0031

  using auxiliary pumps, e.g. pump driven by a different power source than the engine · CPC title

• F16H57/0436

  Pumps · CPC title