# US 2016/0258564 A1 · Rotary joint

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- Number: US 2016/0258564 A1
- Document ID: US20160258564A1
- Status: Published application
- Kind: A1
- Application number: 15/031,261
- Filed: 2014-10-15
- Published: 2016-09-08
- Earliest claimed: 2013-10-28
- Assignees: Nippon Pillar Packing Co., Ltd.
- Applicants: Nippon Pillar Packing Co., Ltd.
- Inventors: Takato FUKUMOTO; Yoshinori KIKUYAMA
- Web page: https://patentgrep.com/patent/US20160258564A1

## CPC

- F16L 39/06: of the multiline swivel type, e.g. comprising a plurality of axially mounted modules
- F16J 15/34: with slip-ring pressed against a more or less radial face on one member
- F16J 15/3484: {Tandem seals}
- F16L: PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16J: PISTONS {(specially adapted for dampers F16F9/32)}; CYLINDERS; SEALINGS

## Abstract

A mechanical seal which defines an annular space formed between a case body and a shaft body is included. The mechanical seal includes: a first sealing ring 11 having a first seal surface; a second sealing ring having a second seal surface which slidably contacts with the first seal surface; and a plurality of coil springs provided along the first sealing ring 11 in a circumferential direction and configured to apply axial forces to the first sealing ring 11 to press the first seal surface against the second seal surface. The plurality of coil springs are divided into a plurality of groups, and first regions K1 in each of which occurring distortion is increased by the axial forces of the coil springs that belong to the group and second regions K2 in each of which distortion is smaller than that in each first region K1 are present alternately along the circumferential direction in the first sealing ring 11.

## Claims

### Claim 1

A rotary joint comprising:
a tubular case body having a first flow passage formed therein so as to be opened at an inner peripheral side thereof;
a shaft body provided within the case body so as to be rotatable relative to the case body and having a second flow passage formed therein so as to be opened at an outer peripheral side thereof; and
a mechanical seal provided in an annular space formed between the case body and the shaft body, the mechanical seal defining the annular space to form a flow passage connecting the first flow passage to the second flow passage, wherein
the mechanical seal includes: a first sealing ring attached to the case body and having an annular first seal surface at one side in an axial direction; a second sealing ring attached to the shaft body and having an annular second seal surface which slidably contacts with the first seal surface; and a plurality of elastic members provided along the first sealing ring in a circumferential direction and configured to apply axial forces to the first sealing ring to press the first seal surface against the second seal surface, and
the plurality of elastic members are divided into a plurality of groups each composed of a predetermined number of the elastic members aligned continuously in the circumferential direction, and first regions in each of which occurring distortion is increased by the axial forces of the elastic members that belong to the group and second regions in each of which distortion is smaller than that in each first region are present alternately along the circumferential direction in the first sealing ring.

### Claim 2 (depends on 1)

The rotary joint according to claim 1, wherein an absence section in which the elastic members are not present is interposed between the groups adjacent to each other in the circumferential direction, whereby the first regions and the second regions are present alternately along the circumferential direction in the first sealing ring.

### Claim 3 (depends on 2)

The rotary joint according to claim 2, wherein a circumferential pitch of the elastic members that belong to each of the groups is set so as to be smaller than a circumferential pitch of the elastic members in a case where the plurality of elastic members are assumed to be arranged at equal intervals along the circumferential direction.

### Claim 4 (depends on 1)

The rotary joint according to claim 1, wherein
the plurality of elastic members are arranged at equal intervals along the circumferential direction, and
the groups in each of which a total axial force by the predetermined number of the elastic members is great and the groups in each of which a total axial force by the predetermined number of the elastic members is small are arranged alternately along the circumferential direction, whereby the first regions and the second regions are present alternately along the circumferential direction in the first sealing ring.

### Claim 5 (depends on 1)

The rotary joint according to claim 1, wherein the number of the elastic members included in each of the groups is the same.

### Claim 6 (depends on 1)

The rotary joint according to claim 1, wherein the plurality of elastic members are divided into two to four groups.