Hydraulic cylinder with drift stop

Patent metadata

Field	Value
Publication number	US-9551364-B2
Application number	US-201314047049-A
Country	US
Kind code	B2
Filing date	Oct 7, 2013
Priority date	Oct 15, 2012
Publication date	Jan 24, 2017
Grant date	Jan 24, 2017

Abstract

A hydraulic fluid power cylinder assembly 10 includes a cylinder chamber 14 , a piston 15 , a piston rod 19 and an end cap 21 . End cap 21 includes a drift stop chamber 24 and a drift stop blocking surface 25 . Chamber 24 is in open fluid pressure communication with chamber 14 under all conditions. Piston 15 includes a piston body portion 16 and a drift stop body portion 29 . Drift stop body portion 29 includes a drift stop blocking member 31 and a positioning surface 34 for preventing the blocking member 31 from contacting the walls of cavity 24 and cylinder chamber 14 when disengaged from blocking surface 25 . In one position drift stop body portion 29 is received within drift stop cavity 24 , and blocking member 31 engages blocking surface 25 to prevent unintended movement of piston 15.

First claim

The invention claimed is:

1. A fluid power cylinder assembly comprising a cylinder body and a piston,
the cylinder body having a generally cylindrical interior surface defining a longitudinally extending cylinder chamber,
the piston having a generally cylindrical longitudinally extending piston body portion with a generally cylindrical exterior surface slidably disposed within the cylinder interior surface,
a drift stop body portion fixed to the piston body portion and spaced laterally inwardly from the interior surface of the cylinder body,
a longitudinally extending drift stop cavity defined by a longitudinally extending drift stop cavity wall, the drift stop cavity having an open end opening into the cylinder chamber, the drift stop cavity being in open fluid pressure communication with the cylinder chamber under all conditions,
the drift stop body portion extending longitudinally into the drift stop cavity when the piston body portion and the drift stop body portion are each in one position, the drift stop body portion being longitudinally spaced from the drift stop cavity when the piston body portion and the drift stop body portion are each in another position,
a drift stop blocking surface carried by the drift stop cavity wall, a laterally movable drift stop blocking member carried by the drift stop body portion,
the drift stop blocking member having one position engaging the drift stop blocking surface to limit longitudinal movement of the piston when the piston body portion and the drift stop body portion are each in their one position, and the drift stop blocking member having another position spaced from the drift stop blocking surface when the piston body portion and the drift stop body portion are each in their other position,
wherein the drift stop body portion extends longitudinally from the piston body portion, a combined lateral cross sectional area of the drift stop body portion within the drift stop cavity and piston body portion within the cylinder chamber is substantially equal to a lateral cross sectional area of the cylinder chamber, and the combined lateral cross sectional area is exposed to fluid pressure of the drift stop cavity and cylinder chamber under all conditions, and
wherein the force of fluid pressure acting on the combined lateral cross sectional area provides the sole means for disengaging the drift stop blocking member from the drift stop blocking surface.

2. A fluid power cylinder assembly as set forth in claim 1 , wherein the drift stop blocking member is laterally aligned with and laterally spaced from the drift stop cavity wall when the drift stop body is received in the drift stop cavity.

3. A fluid power cylinder assembly as set forth in claim 1 , wherein the drift stop blocking member is pressure balanced under all conditions.

4. A fluid power cylinder assembly as set forth in claim 1 , including a laterally extending drift stop blocking member passage in the drift stop body portion, and the drift stop blocking member is slidably disposed in the passage.

5. A fluid power cylinder assembly as set forth in claim 1 , including an end cap fixed against movement relative to the cylinder body, and the drift stop cavity is disposed in the end cap.

6. A fluid power cylinder assembly as set forth in claim 1 , including a drift stop blocking member positioning surface, the drift stop blocking member engages the positioning surface to retain the drift stop blocking member away from the drift stop cavity wall and away from the cylinder interior surface when the drift stop blocking member and the drift stop surface are disengaged from one another.

7. A fluid power cylinder assembly as set forth in claim 6 , including a drift stop blocking member spring carried by the drift stop body member, the drift stop spring biases the drift stop blocking member laterally outwardly against the positioning surface when the drift stop blocking member is disengaged from the drift stop blocking surface.

8. A fluid power cylinder assembly as set forth in claim 1 , including a laterally extending drift stop blocking member passage extending laterally from side to side through the drift stop body portion, the drift stop blocking member is slidably disposed in the passage, a drift stop blocking member spring is disposed in the passage, a drift stop blocking member positioning surface is disposed in the passage near one open end region of the passage, the positioning surface is a reduced diameter region of the passage, the drift stop blocking member engages the positioning surface to limit the lateral movement of the drift stop blocking member in a direction toward the drift stop cavity wall when the drift stop blocking member is spaced from the drift stop blocking surface, a drift stop blocking member spring stop is disposed in the passage near another open end region of the passage, and the spring is disposed intermediate the spring stop and the drift stop blocking member.

9. A fluid power cylinder assembly as set forth in claim 8 , wherein the drift stop blocking surface includes an annular ridge extending laterally inwardly from the drift stop cavity wall and at least one substantially conical surface.

10. A fluid power cylinder assembly as set forth in claim 1 , wherein the drift stop blocking member is generally spherical.

11. A fluid power cylinder assembly as set forth in claim 1 , wherein the drift stop body portion extends longitudinally from the piston body portion, and the piston body portion and the drift stop body portion are of integral single piece construction.

12. A fluid power cylinder assembly as set forth in claim 1 , wherein the piston body portion and the drift stop body portion are concentrically disposed along a longitudinal axis.

13. A hydraulic fluid power cylinder assembly comprising a cylinder body, a piston, a piston rod and an end cap, all disposed along a longitudinal axis,
the cylinder body having a generally cylindrical interior surface defining a longitudinally extending cylinder bore,
the piston having a generally cylindrical longitudinally extending piston body portion with a generally cylindrical exterior surface slidably disposed within the cylinder bore, a drift stop body portion extending longitudinally from the piston body portion and being spaced laterally inwardly from the Interior surface of the cylinder body,
the end cap having a longitudinally extending drift stop cavity defined by a longitudinally extending drift stop cavity wall, the drift stop cavity wall having an open end opening into the cylinder bore, a drift stop ridge extending laterally inwardly from the drift stop cavity wall and terminating at a drift stop ridge crest,
the drift stop body portion extending longitudinally into the drift stop cavity when the piston body portion and the drift stop body portion are in a first and in a second position, the drift stop body portion being longitudinally spaced from the drift stop cavity when the piston body portion and the drift stop body portion are in a third position,
the drift stop body portion including a laterally extending passage, a drift stop blocking member slidably disposed in the passage for lateral movement relative to the drift stop cavity wall and relative to the drift stop ridge crest and relative to the cylinder interior surface, a drift stop blocking member spring disposed in the drift stop passage and biasing the drift stop blocking member laterally outwardly, a drift stop blocking member positioning surface in the drift stop passage,
the drift stop blocking member having a first position biased by the drift stop spring against and engaging the positioning surface when the drift st

Assignees

• Parker Hannifin Corp

Inventors

• Maurer Garrett
• Alaman Romell

Classifications

• F15B15/02 Primary

  Mechanical layout characterised by the means for converting the movement of the fluid-actuated element into movement of the finally-operated member · CPC title

• F15B15/261 Primary

  using positive interengagement, e.g. balls and grooves, for locking in the end positions · CPC title