Hydraulic control valve

Patent metadata

Field	Value
Publication number	US-10641297-B2
Application number	US-201816104423-A
Country	US
Kind code	B2
Filing date	Aug 17, 2018
Priority date	Aug 17, 2018
Publication date	May 5, 2020
Grant date	May 5, 2020

Abstract

A new means of achieving a valve float position in a closed centered hydraulic control valve. The valve has a main spool position whereby pressure compensator load sense control pressure is drained to tank through the main spool. Secondly, a pin acts on the pressure compensator to prevent the main pump flow from reaching the main section spool. Finally, the new spool position adds a connection from the consumer to tank, enabling a float position.

First claim

What is claimed is:

1. A pressure compensated hydraulic control valve comprising:
a pair of consumer workports for attachment to a hydraulic implement;
a pump port for attachment to a variable displacement pump;
a tank port for attachment to a hydraulic fluid tank;
a main valve spool including passages to selectively connect a pressure compensated pump flow channel from the pump port, a tank channel to the tank port, a variable displacement pump load sense channel, and the pair of consumer workports, wherein the main valve spool includes:
a neutral spool position in which the pressure compensated pump flow channel is blocked and the variable displacement pump load sense channel is connected to the tank channel,
a first power position connecting the pressure compensated pump flow channel to a first one of the pair of consumer workports, connecting the first one of the pair of consumer workports to the variable displacement pump load sense channel, and connecting a second one of the pair of consumer workports to the tank channel,
a second power position connecting the pressure compensated pump flow channel to the second one of the pair of consumer workports, connecting the second one of the pair of consumer workports to the variable displacement pump load sense channel, and connecting the first one of the pair of consumer workports to the tank channel, and
a fourth spool position connecting both of the pressure compensated pump flow channel and the tank channel to both of the pair of consumer workports, the fourth spool position further connecting the variable displacement pump load sense channel to the tank channel;

a pressure compensator spool including passages to control output to a valve spool inlet of the main valve spool from the pump port that supplies flow from the variable displacement pump, wherein a connection from the load sense channel and a connection from the pump port act together to maintain a pressure drop from the pump port to the load sense channel; and
a spool pin positioned to act on and urge the pressure compensator spool toward a position in which the pressure compensator spool blocks communication between the pump port and the valve spool inlet of the main valve spool, the spool pin being exposed to a first hydraulic fluid passage that acts on the spool pin separate from the connection to the pressure compensator spool from the pump port that acts together with the connection from the load sense channel to maintain the pressure drop from the pump port to the load sense channel.

2. The pressure compensated hydraulic control valve of claim 1 ,
wherein the connection from the pump port, which acts along with the connection from load sense channel on the pressure compensator spool, is internal to the pressure compensator spool.

3. The pressure compensated hydraulic control valve of claim 1 , wherein the first hydraulic fluid passage that acts on the spool pin is in communication with a second hydraulic fluid passage extending to an end of the main valve spool.

4. The pressure compensated hydraulic control valve of claim 3 , wherein the fourth spool position is defined at the end of the main valve spool.

5. The pressure compensated hydraulic control valve of claim 1 , wherein in the fourth spool position, the connection of both of the pressure compensated pump flow channel and the tank channel to both of the pair of consumer workports is within the main valve spool.

6. The pressure compensated hydraulic control valve of claim 5 , wherein in the fourth spool position, the connection between the variable displacement pump load sense channel and the tank channel is within the main valve spool.

7. The pressure compensated hydraulic control valve of claim 1 , wherein the main valve spool is biased to the neutral position.

8. A method for operating a work machine with a pressure compensated hydraulic control valve, the method comprising:
supplying hydraulic fluid from a variable displacement pump through a pump port, a pressure compensator, and a pressure compensated pump flow channel to a valve spool inlet of a main valve spool;
moving the main valve spool from a neutral position to a first power position to connect the pressure compensated pump flow channel to a first one of a pair of consumer workports, to connect the first one of the pair of consumer workports to a variable displacement pump load sense channel, and to connect a second one of the pair of consumer workports to a tank channel;
moving the main valve spool from the neutral position to a second power position to connect the pressure compensated pump flow channel to the second one of the pair of consumer workports, to connect the second one of the pair of consumer workports to the variable displacement pump load sense channel, and to connect the first one of the pair of consumer workports to the tank channel;
moving the main valve spool from the second power position to a float position to connect both of the pressure compensated pump flow channel and the tank channel to both of the pair of consumer workports, and to connect the variable displacement pump load sense channel to the tank channel; and
simultaneous with moving the main valve spool to the float position, moving a pressure compensator spool to a pump isolation position that blocks the valve spool inlet of the main valve spool from the pump port that supplies flow from the variable displacement pump.

9. The method of claim 8 , wherein the spool of the pressure compensator is moved to the pump isolation position by a spool pin.

10. The method of claim 9 , wherein the spool pin is acted upon by hydraulic fluid in a first passage that is in communication with a second passage extending to an end of the main valve spool that defines the float position of the main valve spool.

11. The method of claim 8 , wherein both of the pressure compensated pump flow channel and the tank channel are connected to both of the pair of consumer workports within the main valve spool float position.

12. The method of claim 8 , wherein the variable displacement pump load sense channel and the tank channel are connected within the main valve spool float position.

13. The method of claim 8 , wherein moving the main valve spool from the neutral position includes overcoming a bias force on the main valve spool.

Assignees

• Bosch Gmbh Robert

Inventors

• Webel Roger A
• Bialosky Evan D
• Graham Scott C
• Karsten Frank C
• Lacey Daniel S
• Sailer Jr Richard F

Classifications

• F15B13/0417 Primary

  Load sensing elements; Internal fluid connections therefor; Anti-saturation or pressure-compensation valves · CPC title

• F15B13/0402

  for linearly sliding valves, e.g. spool valves · CPC title

• F15B13/026

  Pressure compensating valves · CPC title

• F15B2211/5756

  for opening a valve · CPC title

• F15B2211/30535

  the pressure compensating valve is arranged between pressure source and directional control valve · CPC title