Hydraulic control circuit for operating a split actuator mechanical mechanism

• US 6,715,402 B2
• Filed: 02/26/2002
• Issued: 04/06/2004
• Est. Priority Date: 02/26/2002
• Status: Expired due to Fees

• Current Assignee: Husco International Incorporated
• Original Assignee: Husco International Incorporated
• Inventors: Pfaff, Joseph L., Stephenson, Dwight B.
• Primary Examiner(s): Lopez, F. Daniel
• Application Number:
  US10/082,862
• Publication Number:
  US 20030159577A1
• Time in Patent Office: 770 Days
• Field of Search: 604/03, 604/06, 915/21, 915/23, 915/26, 915/29, 915/31, 915/33, 914/54, 914/64
• US Class Current: 91/526
• CPC Class Codes: F15B 11/006 Hydraulic "Wheatstone bridge" circuits, i.e. with four nodes, P-A-T-B, and on-off or proportional valves in each link
• CPC Class Codes: F15B 11/042 by means in the feed line , i.e. "meter in"F15B11/046, F15B11/05 take precedence
• CPC Class Codes: F15B 11/044 by means in the return line , i.e. "meter out"F15B11/046, F15B11/05 take precedence
• CPC Class Codes: F15B 11/22 Synchronisation of the movement of two or more servomotors
• CPC Class Codes: F15B 21/08 Servomotor systems incorporating electrically operated control means F15B21/02, F15B21/065 take precedence
• CPC Class Codes: F15B 2211/20546 variable capacity
• CPC Class Codes: F15B 2211/30575 in a Wheatstone Bridge arrangement (also half bridges)
• CPC Class Codes: F15B 2211/3111 the pump port being closed in the centre position, e.g. so-called closed centre
• CPC Class Codes: F15B 2211/3144 the positions being continuously variable, e.g. as realised by proportional valves
• CPC Class Codes: F15B 2211/31588 having a single pressure source and multiple output members
• CPC Class Codes: F15B 2211/329 actuated by fluid pressure
• CPC Class Codes: F15B 2211/351 Flow control by regulating means in feed line, i.e. meter-in control
• CPC Class Codes: F15B 2211/353 Flow control by regulating means in return line, i.e. meter-out control
• CPC Class Codes: F15B 2211/45 Control of bleed-off flow, e.g. control of bypass flow to the return line
• CPC Class Codes: F15B 2211/6309 the pressure being a pressure source supply pressure
• CPC Class Codes: F15B 2211/6313 the pressure being a load pressure
• CPC Class Codes: F15B 2211/6355 having valve means
• CPC Class Codes: F15B 2211/6652 Control of the pressure source, e.g. control of the swash plate angle
• CPC Class Codes: F15B 2211/6654 Flow rate control
• CPC Class Codes: F15B 2211/7056 Tandem cylinders
• CPC Class Codes: F15B 2211/7128 : the chambers being connected in parallel

Abstract

A system for simultaneously operating first and second hydraulic cylinders has an inlet node for connection to a source of pressurized fluid and an outlet node for connection to a tank. A two-position, three-way primary control valve has a first port connected to the inlet node, a second port connected to the outlet node, and a common port. A first electrohydraulic proportional valve connects the common port to a first port of the first cylinder, and a second electrohydraulic proportional valve connects the common port to a first port of the second cylinder. A third electrohydraulic proportional valve connects the inlet node to a second port of the first cylinder and a second port of the second cylinder. Selectively operating the primary control valve and one of the third and fourth electrohydraulic proportional valves determines the direction in which the first and second cylinders move. Operation of the first and second electrohydraulic proportional valves meters hydraulic fluid to or from the first and second cylinders to control the rate of that movement.

Claims

1. A hydraulic system for operating first and second actuators each having first and second ports, said hydraulic system comprising:

a primary control valve having one port for connection to a source of pressurized hydraulic fluid, another port for connection to a tank for hydraulic fluid, and a common port;

a bidirectional first control valve connecting the common port of the primary control valve to the first port of the first actuator;

a bidirectional second control valve connecting the common port of the primary control valve to the first port of the second actuator;

a third control valve connecting both the second port of the first actuator and the second port of the second actuator to the source of pressurized hydraulic fluid; and

a fourth control valve connecting both the second port of the first actuator and the second port of the second actuator to the tank for hydraulic fluid.

2. The hydraulic system as recited in claim 1 wherein the primary control valve is a two-position, three-way valve.

3. The hydraulic system as recited in claim 1 wherein the primary control valve has a first position in which the one port is connected to the common port, and a second position in which the other port is connected to the common port.

4. The hydraulic system as recited in claim 1 wherein the first control valve, the second control valve, the third control valve, and the fourth control valve are proportional valves.

5. The hydraulic system as recited in claim 1 further comprising:

a first mode of operation in which the primary control valve couples the source of pressurized hydraulic fluid to the common port, the first, second and fourth control valves are open, and the third control valve is closed; and

a second mode of operation in which the primary control valve couples the tank for hydraulic fluid to the common port, the first, second and third control valves are open, and the fourth control valve is closed.

6. The hydraulic system as recited in claim 5 wherein in at least one of the first and second modes of operation, the first and second control valves are operated to meter flow of fluid.

7. The hydraulic system as recited in claim 5 wherein in the first mode of operation, the fourth control valve is operated to meter flow of fluid.

8. The hydraulic system as recited in claim 5 wherein in the second mode of operation, the third control valve is operated to meter flow of fluid there through.

9. The hydraulic system as recited in claim 1 further comprising a mode of operation in which the primary control valve couples the tank for hydraulic fluid to the common port, the first, second and fourth control valves are open, and the third control valve is closed.

10. The hydraulic system as recited in claim 1 wherein the third control valve and the fourth control valve are bidirectional valves.

11. The hydraulic system as recited in claim 10 further comprising:

a first mode of operation in which the primary control valve couples the source of pressurized hydraulic fluid to the common port, the first, second and third control valves are open, and the fourth control valve is closed;

a second mode of operation in which the primary control valve couples the tank for hydraulic fluid to the common port, the first, second and fourth control valves are open, and the third control valve is closed; and

a float mode of operation in which the primary control valve couples the tank for hydraulic fluid to the common port, the first, second and fourth control valves are open, and the third control valve is closed.

12. The hydraulic system as recited in claim 1 wherein the first control valve, the second control valve, the third control valve, and the fourth control valve are electrohydraulic proportional pilot valves.

13. The hydraulic system as recited in claim 1 further comprising a proportional return line control valve coupling the hydraulic system to the tank for hydraulic fluid.

14. The hydraulic system as recited in claim 1 further comprising an unloader valve coupling the hydraulic system to the source of pressurized hydraulic fluid.

15. The hydraulic system as recited in claim 1 wherein the primary control valve, the first control valve, the second control valve, the third control valve, and the fourth control valve are electrically operated.

16. The hydraulic system as recited in claim 15 further comprising an electronic controller operatively connected to the primary control valve, the first control valve, the second control valve, the third control valve, and the fourth control valve.

17. A hydraulic system for operating first and second actuators each having first and second ports, said hydraulic system comprising:

an inlet node for connection to a source of pressurized hydraulic fluid;

an outlet node for connection to a tank for hydraulic fluid;

a primary control valve having a common port and being connected to the inlet node and the outlet node, wherein the primary control valve has a first position in which the inlet node is connected to the common port and has a second position in which the outlet node is connected to the common port;

a bidirectional first proportional valve connected between the common port of the primary control valve and the first port of the first actuator;

a bidirectional second proportional valve connected between the common port of the primary control valve and the first port of the second actuator;

a third proportional valve connected between the inlet node and both the second port of the first actuator and the second port of the second actuator; and

a fourth proportional valve connected between the inlet node and both the second port of the first actuator and the second port of the second actuator.

18. The hydraulic system as recited in claim 17 further comprising a proportional return line control valve selectively coupling the hydraulic system to the tank for hydraulic fluid.

19. The hydraulic system as recited in claim 17 further comprising an unloader valve selectively coupling the source of pressurized hydraulic fluid to the outlet node.

20. The hydraulic system as recited in claim 17 wherein the first proportional valve, the second proportional valve, the third proportional valve, and the fourth proportional valve are electrohydraulic valves.

21. The hydraulic system as recited in claim 17 wherein the first proportional valve, the second proportional valve, the third proportional valve, and the fourth proportional valve are pilot valves.

22. The hydraulic system as recited in claim 17 wherein the third proportional valve and the fourth proportional valve are bidirectional valves.

23. A hydraulic system for operating first and second cylinders each having first and second ports, said hydraulic system comprising:

an inlet node for connection to a source of pressurized hydraulic fluid;

an outlet node for connection to a tank for hydraulic fluid;

a hydraulic line connected to both the second port of the first cylinder and the second port of the second cylinder;

a primary control valve having a common port and being connected to the inlet node and the outlet node, wherein the primary control valve has a first position in which the inlet node is connected to the common port and has a second position in which the outlet node is connected to the common port;

a bidirectional first electrohydraulic proportional valve selectively connecting the common port of the primary control valve to the first port of the first cylinder;

a bidirectional second electrohydraulic proportional valve selectively connecting the common port of the primary control valve to the first port of the second cylinder;

a bidirectional third electrohydraulic proportional valve selectively connecting the hydraulic line to the inlet node; and

a bidirectional fourth electrohydraulic proportional valve selectively connecting the hydraulic line to the outlet node.

24. The hydraulic system as recited in claim 23 further comprising a proportional return line control valve selectively coupling the outlet node to the tank for hydraulic fluid.

25. The hydraulic system as recited in claim 23 further comprising an unloader valve selectively coupling the inlet node to the outlet node.

26. The hydraulic system as recited in claim 23 wherein the first proportional valve, the second proportional valve, the third proportional valve, and the fourth proportional valve are pilot valves.