HYDRAULIC SYSTEM WITH RETURN PRESSURE CONTROL

• US 20130298542A1
• Filed: 03/21/2011
• Published: 11/14/2013
• Est. Priority Date: 12/17/2010
• Status: Abandoned Application

• Current Assignee: Parker-Hannifin Corporation
• Original Assignee: Parker-Hannifin Corporation
• Inventors: Lowman, Roger, Franzoni, Germano, Harsia, Jarmo A.
• Application Number:
  US13/994,927
• Publication Number:
  US 20130298542A1
• Time in Patent Office: Days
• US Class Current: 60/327
• CPC Class Codes: F15B 11/00 Servomotor systems without provision for follow-up action; Circuits thereforF15B3/00 takes precedence
• CPC Class Codes: F15B 15/18 Combined units comprising both motor and pump
• CPC Class Codes: F15B 2211/3127 Floating position connecting the working ports and the return line
• CPC Class Codes: F15B 2211/3144 the positions being continuously variable, e.g. as realised by proportional valves
• CPC Class Codes: F15B 2211/50518 using pressure relief valves
• CPC Class Codes: F15B 2211/50545 using braking valves to maintain a back pressure
• CPC Class Codes: F15B 2211/5156 being connected to a return line and a directional control valve
• CPC Class Codes: F15B 2211/6306 representing a pressure
• CPC Class Codes: F15B 2211/632 representing a flow rate
• CPC Class Codes: F15B 2211/6336 representing a state of the output member, e.g. position, speed or acceleration
• CPC Class Codes: F15B 2211/6346 representing a state of input means, e.g. joystick position
• CPC Class Codes: Y10T 137/7837 Direct response valves [i.e., check valve type]
• CPC Class Codes: Y10T 137/86027 Electric

Abstract

A hydraulic system (10) includes an electronically-controlled counter-pressure valve (60) that enables backpressure in a return line (36) of the system to be varied by a control unit (64). The system allows active control of the pressure in the return line to produce different return pressures for different situations. A higher return line pressure may be set to improve make-up or recirculating flow through an anti-cavitation valve (50). This may improve controllability of functions that benefit from backpressure, such as lowering loads (12). The control unit that controls the counter-pressure valve may take into account any of a wide variety of possible inputs when setting the counter-pressure valve.

Claims

1. A hydraulic system comprising:

a control valve for selectively controlling flow to and from a hydraulic load, wherein the control valve has a supply port that receives pressurized fluid, and wherein the control valve has a return port that directs fluid away from the control valve;

an electrically-controlled counter-pressure valve that maintains backpressure at the return port; and

a control unit that is operably coupled to the electrically-controlled counter-pressure valve to selectively set the backpressure at the return port.

2. The hydraulic system of claim 1, wherein the return port is coupled, via a regeneration line, to a feed port of the control valve connects the control valve to the hydraulic load.

3. The hydraulic system of claim 2, wherein the regeneration line has an anti-cavitation check valve that allows flow only from the return port to the feed port.

4. The hydraulic system of any of claims 1 to 3,

further comprising:

a pump that supplies fluid to the supply port; and

a prime mover operatively coupled to the pump, to power the pump;

wherein the control unit is operably coupled to at least one of the pump or the prime mover; and

wherein the control unit selectively sets backpressure at the return port at least in part on information concerning the pump or the prime mover.

5. The hydraulic system of any of claims 1 to 4, wherein the control unit sets the backpressure at the return port based on one or more of a primer mover speed, a pump flow, a functional command to the hydraulic load, functional load condition regarding the hydraulic load, a functional position of the hydraulic load, a flow rate to the hydraulic load, a flow rate from the hydraulic load, a flow rate in a return line coupled to the return port, and a return line pressure in the return line.

6. The hydraulic system of any of claims 1 to 5, further comprising the hydraulic load.

7. The hydraulic system of claim 6, wherein the hydraulic load is an actuator.

8. The hydraulic system of claim 6 or claim 7,

further comprising:

an additional hydraulic load; and

an additional control valve for selectively controlling flow to and from the additional hydraulic load;

wherein the control unit selectively sets the backpressure in a return line coupled to the return port, at least in part on inputs received from both of the hydraulic loads or from both of the control valves.

9. The hydraulic system of any of claims 1 to 8,

further comprising one or more sensors operably coupled to the control unit;

wherein the control unit selectively sets the backpressure at the return port at least in part on information received from the one or more sensors.

10. The hydraulic system of claim 9, wherein the one or more sensors includes a sensor that provides an indication of position of the control valve.

11. The hydraulic system of claim 9, wherein the one or more sensors includes a sensor that provides an indication of position of the hydraulic load.

12. The hydraulic system of claim 9, wherein the one or more sensors includes a flow sensor.

13. The hydraulic system of claim 9, wherein the one or more sensors includes a pressure sensor.

14. The hydraulic system of any of claims 1 to 13, further comprising an accumulator coupled to a return line that is coupled to the return port.

15. The hydraulic system of claim 14, further comprising an accumulator control valve that controls flow between the accumulator and the return line.

16. The hydraulic system of claim 14 or claim 15, wherein the control unit selectively sets the backpressure in the return line at least in part on a pressure in the accumulator.

17. A method of operating a hydraulic system, the method comprising:

actively controlling backpressure in a return line of the hydraulic system, wherein the actively controlling includes;

receiving one or more inputs at an electronic control unit of the system; and

the electronic control unit setting the pressure setting of a counter-pressure valve of the system that is in the return line, as a function of the one or more inputs.

18. The method of claim 17, wherein one or more inputs includes one or more of a primer mover speed, a pump flow, a functional command to a hydraulic load of the system, a functional load condition regarding the hydraulic load, a functional position of the hydraulic load, a flow rate to the hydraulic load, a flow rate from the hydraulic load, a flow rate in a return line of the system, and a return line pressure in the return line.

19. The method of claim 17, wherein the actively controlling the backpressure includes raising the backpressure to recirculate hydraulic fluid from the return line to a flow line of the hydraulic system, wherein the flow line is between a control valve of the hydraulic system and a load of the hydraulic system.

20. The method of claim 19, wherein the raising the backpressure includes recirculating the hydraulic fluid through an anti-cavitation check valve in a regeneration line that connects the return line to the flow line.