Piston assembly having reduced extend force and reduced displacement volume

Patent metadata

Field	Value
Publication number	US-11111936-B2
Application number	US-202016998643-A
Country	US
Kind code	B2
Filing date	Aug 20, 2020
Priority date	Aug 20, 2019
Publication date	Sep 7, 2021
Grant date	Sep 7, 2021

Abstract

A piston assembly including a shaft having a piston arrangement. The piston arrangement has a retract-area on one side and a extend-area on the opposite side. The retract-area is larger than the extend-area so that when fluid exerts a force on the retract-area the piston arrangement generates and applies a retract force to the shaft. Upon release of the fluid pressure to the retract-area and application of the fluid pressure to the extend-area the piston arrangement generates and applies an extend force to the shaft. The retract force is greater than or equal to the extend force.

First claim

What is claimed is:

1. A piston assembly comprising:
a shaft;
a piston arrangement positioned on the shaft;
the piston arrangement having a retract-area configured for retracting the shaft and an extend-area configured for extending the shaft;
the retract-area being greater than the extend-area so that upon application of a fluid pressure to the retract-area the piston arrangement generates and applies a retract force to the shaft and upon release of the fluid pressure to the retract-area and application of the fluid pressure to the extend-area the piston arrangement generates and applies an extend force to the shaft, the fluid pressure having a predetermined magnitude; and
wherein the retract force is greater than the extend force;
the piston arrangement comprises a piston head secured to the shaft, the piston head having at least one aperture extending therethrough;
the piston arrangement comprises a retract head moveably mounted on the shaft;
the piston arrangement being configured to cause extension of the shaft from a retracted position to an extended position and to cause retraction of the shaft from the extended position to the retracted position; and
a variable volume reservoir formed between the piston head and the retract head.

2. The piston assembly of claim 1 , wherein the at least one aperture comprises a plurality of holes extending through the piston head.

3. The piston assembly of claim 1 , wherein the at least one aperture comprises a flow path for flow of actuation fluid between opposing sides of the piston head.

4. The piston assembly of claim 1 , wherein the at least one aperture has a cross sectional area of a predetermined magnitude, wherein the extend-area being calculated by subtracting the cross sectional areas of the at least one aperture from an overall axially projected area of the piston head.

5. The piston assembly of claim 1 , wherein the retract head comprises an annular disc having an inside surface defining a bore extending axially through the annular disc.

6. The piston assembly of claim 5 , wherein the inside surface comprises at least one first groove with a first seal disposed therein, the first seal slidingly and sealing engaging the shaft.

7. The piston assembly of claim 1 , wherein the retract head is a barrier to flow of actuation fluid across the retract head.

8. The piston assembly of claim 1 , wherein the retract head comprises a first circumferential surface having a second groove formed therein and a second seal disposed in the second groove; and
the piston head comprising a second circumferential surface having a third groove formed therein and a third seal being disposed in the third groove;
wherein the second seal and the third seal are configured to slidingly and sealingly engage an interior surface of a housing configured to retain the piston assembly.

9. The piston assembly of claim 1 , wherein the variable volume reservoir is at least one of:
(a) at least one increasing and decreasing, during at least a portion of the extension of the shaft to conserve actuation fluid ported to and from the piston assembly; and
(b) at least one of increasing and decreasing, during at least a portion of the retraction of the shaft, to conserve actuation fluid ported to and from the piston assembly.

10. The piston assembly of claim 1 , wherein the variable volume reservoir is at least one of:
(a) constant during at least a portion of the extension of the shaft to conserve actuation fluid ported to and from the piston assembly; and
(b) constant during at least a portion of the retraction of the shaft, to conserve actuation fluid ported to and from the piston assembly.

11. A piston assembly comprising:
a shaft;
a piston arrangement positioned on the shaft, the piston arrangement being configured to cause extension of the shaft from a retracted position to an extended position and to cause retraction of the shaft from the extended position to the retracted position; and
the piston arrangement comprising a variable volume reservoir, the variable volume reservoir being at least one of:
(a) at least one of increasing and decreasing, during at least a portion of the extension of the shaft, to conserve actuation fluid ported to and from the piston assembly;
(b) at least one of increasing and decreasing, during at least a portion of the retraction of the shaft, to conserve actuation fluid ported to and from the piston assembly;
(c) constant during at least a portion of the extension of the shaft to conserve actuation fluid ported to and from the piston assembly; and
(d) constant during at least a portion of the retraction of the shaft, to conserve actuation fluid ported to and from the piston assembly;
the piston arrangement has a retract-area configured for retracting the shaft and an extend-area configured for extending the shaft;
the retract-area being greater than the extend-area so that upon application of a fluid pressure to the retract-area the piston arrangement generates and applies a retract force to the shaft and upon release of the fluid pressure to the retract-area and application of the fluid pressure to the extend-area the piston arrangement generates and applies an extend force to the shaft; and
wherein the retract force is greater than the extend force.

12. The piston assembly of claim 11 , wherein:
the piston arrangement comprises a piston head secured to the shaft, the piston head having at least one aperture extending therethrough;
the piston arrangement comprises a retract head moveably mounted on the shaft;
the piston arrangement being configured to cause extension of the shaft from a retracted position to an extended position and to cause retraction of the shaft from the extended position to the retracted position.

13. The piston assembly of claim 12 , wherein the at least one aperture comprises a plurality of holes extending through the piston head.

14. The piston assembly of claim 12 , wherein the at least one aperture comprises a flow path for flow of actuation fluid between opposing sides of the piston head.

15. The piston assembly of claim 11 , wherein the piston arrangement comprises a piston head secured to the shaft, the piston head having at least one aperture extending therethrough; and
the at least one aperture has a cross sectional area of a predetermined magnitude wherein the extend-area being calculated by subtracting the cross sectional areas of the at least one aperture from an overall axially projected area of the piston head.

16. The piston assembly of claim 12 , wherein the retract head comprises an annular disc having an inside surface defining a bore extending through the annular disc.

17. The piston assembly of claim 16 , wherein the inside surface comprises at least one first groove with a first seal disposed therein, the first seal slidingly and sealing engaging the shaft.

18. The piston assembly of claim 12 , wherein the retract head is a barrier to flow of actuation fluid across the retract head.

19. The piston assembly of claim 12 , wherein the retract head comprises a first circumferential surface having a second groove formed therein and a second seal disposed in the second groove; and
the piston head comprising a second circumferential surface having a third groove formed therein and a third seal being disposed in the third groove;
wherein the second seal and the third seal are configured to slidingly and sealingly engage an interior surface of a housing configured to retain the piston assembly.

20

Assignees

• Roller Bearing Co America Inc

Inventors

• Alger Mark
• Brown Brandon
• Ulliman Jeremy

Classifications

• F16J1/04

  Resilient guiding parts, e.g. skirts, particularly for trunk pistons · CPC title

• F15B15/221

  for accelerating the stroke, e.g. by area increase · CPC title

• F16J1/008

  with sealing lips · CPC title

• F16J10/02 Primary

  Cylinders designed to receive moving pistons or plungers · CPC title

• F15B15/17 Primary

  of differential-piston type · CPC title