Hydraulic cylinder

Patent metadata

Field	Value
Publication number	US-10480546-B2
Application number	US-201515509651-A
Country	US
Kind code	B2
Filing date	Aug 24, 2015
Priority date	Sep 12, 2014
Publication date	Nov 19, 2019
Grant date	Nov 19, 2019

Abstract

A piston rod and a rod cover which constitute this hydraulic cylinder are configured from aluminum or an aluminum alloy. An alumite coating film is formed on at least a part of the inner wall surface of the rod cover that constitutes a rod insertion hole, and a diamond-like carbon coating film is formed on the outer wall surface of the piston rod, said diamond-like carbon coating film being in sliding contact with the alumite coating film.

First claim

The invention claimed is:

1. A fluid pressure cylinder comprising:
a cylinder main body in which a cylinder hole is formed;
a piston disposed in the cylinder hole and which is displaced along an axial direction under an action of a working fluid;
a piston rod connected to the piston; and
a rod cover in which a rod insertion hole is formed through which the piston rod is inserted;
wherein the piston rod and the rod cover are constituted from aluminum or an aluminum alloy;
an alumite film or a diamond-like carbon film is formed on at least a portion of an inner wall surface of the rod cover constituting the rod insertion hole;
in the case that the alumite film is formed on the inner wall surface of the rod cover, a diamond-like carbon film that slides in contact with the alumite film is formed on an outer wall surface of the piston rod, whereas in the case that the diamond-like carbon film is formed on the inner wall surface of the rod cover, an alumite film that slides in contact with the diamond-like carbon film is formed on the outer wall surface of the piston rod;
an annular groove provided in the inner wall surface of the rod cover;
a rod packing provided in a portion of the annular groove; and
a lubricant provided in another portion of the annular groove, said another portion of the groove not having the rod packing, whereby said another portion of the groove comprises a lubricant accommodating groove wherein a length of the lubricant accommodating groove in the axial direction is between ⅕ and ⅘ of a length of the alumite film that slides in contact with the diamond-like carbon film,
wherein said another portion of the annular groove is located at a side of the rod packing which is opposite the piston along the axial direction.

2. The fluid pressure cylinder according to claim 1 , wherein:
the alumite film is formed on the inner wall surface of the rod cover; and
the diamond-like carbon film that slides in contact with the alumite film is formed on an outer wall surface of the piston rod.

Assignees

• Smc Corp

Inventors

• Okuhira Hiroyuki
• Imai Kenji
• YANASE Tatsunori

Classifications

• F15B2215/305

  characterised by the use of special materials · CPC title

• F15B15/1461 Primary

  Piston rod sealings · CPC title

• F16J7/00

  Piston-rods · CPC title

• C25D11/04

  of aluminium or alloys based thereon · CPC title

• F15B15/1433 Primary

  End caps (F15B15/1438 takes precedence) · CPC title