Fluid pressure cylinder

Patent metadata

Field	Value
Publication number	US-9784291-B2
Application number	US-201113578381-A
Country	US
Kind code	B2
Filing date	Feb 1, 2011
Priority date	Feb 15, 2010
Publication date	Oct 10, 2017
Grant date	Oct 10, 2017

Abstract

A piston of a fluid pressure cylinder comprises a sealing ring interposed in a sealing ring accommodation groove, a piston ring that is interposed in a piston ring accommodation groove of the piston and comprises a fractured portion, and a backup ring that is attached to an outer peripheral surface of the piston and contacts the sealing ring and the piston ring. A groove for holding the backup ring is not required, and therefore a diameter of the piston can be reduced relative to the sealing ring. As a result, attachment of the sealing ring to the piston is simplified.

First claim

The embodiments of this invention in which an exclusive property or privilege is claimed are defined as follows:

1. A fluid pressure cylinder, comprising:
a cylinder tube having a central axis and an inner peripheral surface that is cylindrical about the central axis;
a piston that is accommodated in the cylinder tube, is slidable against the inner peripheral surface of the cylinder tube, and defines a first side chamber and an opposite, second side chamber within the cylinder tube;
a sealing ring held in a sealing ring accommodation groove formed in a circumferential direction in an outer peripheral surface of the piston, the sealing ring configured to cut off the first side chamber from the opposite, second side chamber;
a first piston ring that is held in a first piston ring accommodation groove formed in the circumferential direction in the outer peripheral surface of the piston, and includes a fractured portion which enables a diameter of the first piston ring to increase and reduce;
a second piston ring that is held in a second piston ring accommodation groove formed in the circumferential direction in the outer peripheral surface of the piston, and includes a fractured portion which enables a diameter of the second piston ring to increase and reduce, wherein the first piston ring accommodation groove is located between the second piston ring accommodation groove and the sealing ring accommodation groove;
a backup ring that is attached, without being accommodated in a groove, to the outer peripheral surface of the piston between the sealing ring and the first piston ring, wherein the backup ring has a first backup ring end and a second backup ring end opposite to each other in a central axis direction, the first backup ring end is kept in constant contact with the sealing ring and, simultaneously, the second backup ring end is kept in constant contact with the first piston ring to enable the first piston ring to support a load exerted, via the backup ring, on the sealing ring in the central axis direction; and
a bearing ring that is attached, without being accommodated in a groove, to the outer peripheral surface of the piston between the first piston ring and the second piston ring, the bearing ring configured to support the piston slidably relative to the cylinder tube, wherein the bearing ring has a first bearing ring end and a second bearing ring end opposite to each other in the central axis direction, the first bearing ring end is kept in constant contact with the first piston ring and, simultaneously, the second bearing ring end is kept in constant contact with the second piston ring.

2. The fluid pressure cylinder as defined in claim 1 , wherein
the backup ring, the bearing ring, the second piston ring and the first piston ring are disposed on the piston on a first side of the sealing ring relative to the central axis direction, and
the fluid pressure cylinder further comprises, on a second side of the sealing ring which is opposite to the first side in the central axis direction:
a further first piston ring that is held in a further first piston ring accommodation groove formed in the circumferential direction in the outer peripheral surface of the piston, and includes a fractured portion which enables a diameter of the further first piston ring to increase and reduce;
a further second piston ring that is held in a further second piston ring accommodation groove formed in the circumferential direction in the outer peripheral surface of the piston, and includes a fractured portion which enables a diameter of the further second piston ring to increase and reduce, wherein the further first piston ring accommodation groove is located between the further second piston ring accommodation groove and the sealing ring accommodation groove;
a further backup ring that is attached, without being accommodated in a groove, to the outer peripheral surface of the piston between the sealing ring and the further first piston ring, wherein the further backup ring has a first further backup ring end and a second further backup ring end opposite to each other in the central axis direction, the first further backup ring end is kept in constant contact with the sealing ring and, simultaneously, the second further backup ring end is kept in constant contact with the further first piston ring; and
a further bearing ring that is attached, without being accommodated in a groove, to the outer peripheral surface of the piston between the further first piston ring and the further second piston ring, wherein the further bearing ring has a first further bearing ring end and a second further bearing ring end opposite to each other the central axis direction, the first further bearing ring end is kept in constant contact with the further first piston ring and, simultaneously, the second further bearing ring end is kept in constant contact with the further second piston ring.

3. The fluid pressure cylinder as defined in claim 2 , wherein
the piston has first and second axial ends opposite to each other in the center axis direction, the first axial end is on the first side of the sealing ring, and the second axial end is on the second side of the sealing ring,
each of the sealing ring accommodation groove, the first piston ring accommodation groove, the second piston ring accommodation groove, the further first piston ring accommodation groove, and the further second piston ring accommodation groove is formed in the outer peripheral surface of the piston between the first and second axial ends, and not at the first and second axial ends,
the outer peripheral surface of the piston has no groove between the second piston ring accommodation groove and the first axial end, and
the outer peripheral surface of the piston has no groove between the further second piston ring accommodation groove and the second axial end.

4. The fluid pressure cylinder as defined in claim 3 , wherein
the sealing ring comprises an elastically deformable material,
each of the first piston ring, the second piston ring, the further first piston ring, and the further second piston ring comprises a metal material, and
each of the bearing ring and the further bearing ring comprises synthetic resin.

5. The fluid pressure cylinder as defined in claim 1 , wherein the sealing ring comprises an elastically deformable material.

6. The fluid pressure cylinder as defined in claim 5 , wherein the first piston ring and the second piston ring comprise a metal material.

7. The fluid pressure cylinder as defined in claim 6 , wherein the bearing ring comprises synthetic resin.

8. The fluid pressure cylinder as defined in claim 1 , wherein
the piston has axial ends relative to the center axis direction, and
each of the sealing ring accommodation groove, the first piston ring accommodation groove, and the second piston ring accommodation groove is formed in the outer peripheral surface of the piston other than the axial ends.

9. The fluid pressure cylinder as defined in claim 1 , wherein
the fractured portion of the first piston ring is constituted by end portions of the first piston ring and the fractured portion of the second piston ring is constituted by end portions of the second piston ring, and
the end portions of the first piston ring and the end portions of the second piston ring respectively have L-shaped cutouts.

10. The fluid pressure cylinder as defined in claim 1 , wherein
the backup ring, the bearing ring, the second piston ring and the first piston ring are disposed on the piston on a first side of the sealing ring relative to the central axis direction,
the fluid pressure cylinder further comprises, on a second side of the sealing ring which is

Assignees

• Funato Hiroshi
• Kyb Corp

Inventors

• Funato Hiroshi

Classifications

• F15B15/1452 Primary

  Piston sealings · CPC title

• F16J15/18

  with stuffing-boxes for elastic or plastic packings · CPC title

• F15B15/14

  of the straight-cylinder type · CPC title

• F16J9/12 Primary

  Details · CPC title