# US 11,079,017 B2 · Hydraulic cylinder

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- Number: US 11,079,017 B2
- Document ID: US11079017B2
- Status: Granted
- Kind: B2
- Application number: 16/611,743
- Filed: 2018-02-26
- Published: 2020-04-09
- Granted: 2021-08-03
- Earliest claimed: 2017-05-08
- Assignees: SMC Corporation
- Applicants: Smc Corporation
- Inventors: Tsukasa Odaka
- Web page: https://patentgrep.com/patent/US11079017B2

## CPC

- F16J 1/008: {with sealing lips}
- F16J 9/12: Details
- F15B 15/14: of the straight-cylinder type
- F15B 15/28: Means for indicating the position, e.g. end of stroke
- F16J 7/00: Piston-rods
- F16J: PISTONS {(specially adapted for dampers F16F9/32)}; CYLINDERS; SEALINGS
- F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR

## Abstract

A hydraulic cylinder (10) comprises a cylinder tube (12) having a circular slide hole (13), a piston unit (18), and a piston rod (20). The piston unit (18) has a circular piston body (40), packing (42) that is installed on the outer circumferential portion of the piston body (40), a movable member (44) that is mounted to the outer circumferential portion of the piston body (40) so as to be able to rotate relative to the piston body (40), and a magnet (46) that is held by a magnet holding unit (58) of the movable member (44). Relative rotation of the movable member (44) with respect to the cylinder tube (12) is regulated.

## Claims

### Claim 1

A fluid pressure cylinder comprising:
a cylinder tube including a slide hole with a circular shape inside the cylinder tube;
a piston unit disposed to be reciprocable along the slide hole; and
a piston rod protruding from the piston unit in an axial direction;
wherein the piston unit includes:
a piston body with a circular shape protruding radially outward from the piston rod;
a packing attached to an outer circumferential part of the piston body and brought into slidable contact with an inner circumferential surface of the cylinder tube;
a movable member including a magnet holding portion and mounted at the outer circumferential part of the piston body to be rotatable relative to the piston body; and
a magnet held by the magnet holding portion and disposed in the piston body at a discrete location which is less than an entirety of a circumferential extent of the piston body, wherein:
the piston rod is rotatable relative to the cylinder tube; and
rotation of the movable member relative to the cylinder tube is restricted,
a magnet arrangement groove with an annular shape is formed in the outer circumferential part of the piston body; and
the magnet holding portion is fitted in the magnet arrangement groove.

### Claim 2

A fluid pressure cylinder comprising:
a cylinder tube including a slide hole with a circular shape inside the cylinder tube;
a piston unit disposed to be reciprocable along the slide hole; and
a piston rod protruding from the piston unit its an axial direction;
wherein the piston unit includes:
a piston body with a circular shape protruding radially outward from the piston rod;
a packing attached to an outer circumferential part of the piston body and brought into slidable contact with an inner circumferential surface of the cylinder tube;
a movable member including a magnet holding portion and mounted at the outer circumferential part of the piston body to be rotatable relative to the piston body; and
a magnet held by the magnet holding portion and disposed in the piston body at a discrete location which is less than an entirety of a circumferential extent of the piston body, wherein:
the piston rod is rotatable relative to the cylinder tube; and
rotation of the movable member relative to the cylinder tube is restricted,
a detent groove is provided in the inner circumferential surface of the cylinder tube in an axial direction of the cylinder tube; and
the movable member is provided with a detent protrusion fitted in the detent groove.

### Claim 3 (depends on 2)

The fluid pressure cylinder according to claim 2, wherein:
the movable member includes a circumferential portion extending in the circumferential direction along the outer circumferential part of the piston body;
the magnet holding portion protrudes from the circumferential portion in the axial direction; and
the detent protrusion is provided across an outer surface of the circumferential portion and an outer surface of the magnet holding portion.

### Claim 4 (depends on 2)

The fluid pressure cylinder according to claim 2, wherein a projection inserted in the decent groove to be in slidable contact with an inner surface of the detent groove is disposed on an outer circumferential part of the packing.

### Claim 5 (depends on 3)

The fluid pressure cylinder according to claim 3, wherein:
the magnet holding portion has a magnet receiving groove in which the magnet is fitted; and
the magnet receiving groove passes through the magnet holding portion in the axial direction and is open radially inward.