Regulated pressure supply for a variable-displacement reversible hydraulic motor
View Patent ↗A pressure-control device ( 20 ) includes a controllable variable-displacement reversible hydraulic motor ( 21 ) having a pressure port ( 22 ) and a return port ( 23 ); a source of pressurized fluid (P s ); a fluid return (R); and a pressure regulating valve ( 24 ) operatively interposed between the source, return and pressure port. The pressure regulating valve is operatively arranged to maintain a predetermined pressure at the pressure port regardless of the direction of flow through the pressure port.
1. A pressure-control device, comprising:
a controllable variable-displacement hydraulic motor having a pressure port and a return port;
a source of pressurized fluid;
a fluid return; and
a pressure regulating valve operatively interposed between said source, return and pressure port, said valve being operatively arranged to maintain a predetermined pressure at said pressure port regardless of the direction of flow through said pressure port.
2. The pressure-control device as set forth in claim 1 wherein said motor includes a variable-angle swashplate.
3. The pressure-control device as set forth in claim 1 wherein said valve is a three-way valve.
4. The pressure-control device as set forth in claim 3 wherein said valve has a valve spool.
5. The pressure-control device as set forth in claim 4 wherein said valve has a first spool end chamber communicating with said pressure port.
6. The pressure-control device as set forth in claim 5 wherein said valve has a second spool end chamber, and means associated with said second spool end chamber for biasing said valve spool to move in a direction to increase the pressure at said pressure port.
7. The pressure-control device as set forth in claim 6 wherein said biasing means includes a spring in said second spool end chamber.
8. The pressure-control device as set forth in claim 6 wherein said biasing means is the pressure of fluid in said second spool end chamber.
9. The pressure-control device as set forth in claim 8 and further comprising a 3-way pilot valve operatively arranged between said source, return and second spool end chamber.
10. The pressure-control device as set forth in claim 9 wherein the pressure at said second spool end chamber is selectively one of said source and return pressures.
11. The pressure-control device as set forth in claim 9 wherein said pressure regulating valve has a piston means associated with said first spool end chamber for biasing said valve spool to move in a direction to decrease the pressure at said pressure port, said piston means being loaded by said source pressure.
12. The pressure-control device as set forth in claim 8 wherein the pressure in said second spool end chamber is said predetermined pressure.
13. The pressure-control device as set forth in claim 1 wherein when the fluid flow is out of said pressure port, such flow is directed to said motor return port.