Mechanical seal

Details Mechanical seal Mechanical seal

2001-11-20

2004-02-10

Knight, Anthony (Department: 3676)

Seal for a joint or juncture

Seal between relatively movable parts

Relatively rotatable radially extending sealing face member

C277S393000, C277S548000

Reexamination Certificate

active

06688601

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a mechanical seal to be used as a shaft sealing means for a rotating machine such as a pump or the like.
DESCRIPTION OF THE RELATED ART
FIG. 4
shows a related art mechanical seal to be used as a shaft sealing means for large pumps. In
FIG. 4
, reference numeral
10
designates a housing of a shaft sealing part in a pump. A rotating shaft
20
is arranged in an inner circumference of the housing
10
so as to extend into a rotating machine. Numeral
30
designates a mechanical seal for sealing between the housing
10
and the rotating shaft
20
. The mechanical seal
30
comprises a seal cover
31
, sealing elements
32
, a shaft sleeve
33
, and sealing elements
34
. The seal cover
31
is attached to the outside end of the housing
10
. The sealing elements
32
at a stationary side are attached to the seal cover
31
. The shaft sleeve
33
is externally fitted to the rotating shaft
20
. The sealing elements
34
at a rotating side are attached to the shaft sleeve
33
.
The seal cover
31
is arranged at the outside end of the housing
10
, and is fixed by a bolt-nut
312
.
The sealing elements
32
comprise a bellows
321
and a seal ring
322
. The bellows
321
is arranged in an inner circumferential part of the seal cover
31
so as to extend into the machine. The seal ring
322
is sealed and fitted to a retainer
321
b
of its tip. The bellows
321
comprises, inside the seal cover
31
, an adapter
321
a
, the retainer
321
b
, and a bellows core
321
c
. The adapter
321
a
is attached together with a baffle sleeve
325
via a gasket
324
by a bolt
323
. The retainer
321
b
is arranged to the inside of the machine. The bellows core
321
c
is welded between the adapter
321
a
and the retainer
321
b.
On the other hand, the shaft sleeve
33
is fixed to the rotating shaft
20
by a setscrew
332
. The setscrew
332
is screwed in a radial direction from a sleeve collar
331
. The sleeve collar
331
is arranged in an outer circumference of an enlarged diameter part
33
a
. The enlarged diameter part
33
a
is formed on its end part to the outside of the machine. A packing
333
is interposed between the enlarged part
33
a
of the shaft sleeve
33
and the rotating shaft
20
. This packing
333
is appropriately pressed by a packing gland
335
. The packing gland
335
is given tightening force by a bolt
334
. The bolt
334
is screwed into the sleeve collar
331
.
A setscrew
332
is screwed in a radial direction from the sleeve collar
331
. The setscrew
332
penetrates the enlarged part
33
a
of the shaft sleeve
33
and the packing gland
335
. The setscrew
332
is fitted by a pressure to the outer circumferential surface of the rotating shaft
20
.
Further, the sealing elements
34
comprise a holder
342
and a mating ring
344
. The holder
342
is externally fitted to the inside end
33
b
of the shaft sleeve
33
via the packing
341
. The mating ring
344
is held by the holder
342
via a packing
343
. The mating ring
344
is adapted drivingly to engage in a circumferential direction with a pin
342
a
of the holder
342
at a cutout part
344
a
. The mating ring
344
is also sealed and contacted with the seal ring
322
of the sealing elements
32
by each opposite end face.
At a rear surface of the holder
342
, a collar
346
is attached via a bolt
345
. A pin
346
a
is provided in the circumferential part. The pin
346
a
adapts drivingly to engage in a radial direction with a cutout part
33
c
. The cutout part
33
c
is formed on the inside end
33
b
of the shaft sleeve
33
. Further, between an inner circumferential part of the collar
346
and an inner circumferential part of the holder
342
, two-divided press ring
348
is grasped together with the packing
341
and a spacer
347
pressing therewith. The inner circumferential part of the press ring
348
is fitted to a ring-like groove. The ring-like groove is formed on the outer circumferential surface of the inside end
33
b
of the shaft sleeve
33
. Thereby axial movement of the sealing elements
34
is limited relative to the shaft sleeve
33
.
That is, in the mechanical seal
30
, the end face of the seal ring
322
of the sealing elements
32
slidably contacts with the end face of the mating ring
344
of the sealing elements
34
by enforcement in an axial direction of the bellows
321
. Here the end face of the seal ring
322
is held in a non-rotating state with the seal cover that is attached to the housing
10
. The end surface of the mating ring
344
is rotated integrally with the rotating shaft
20
. Thereby it prevents a sealed fluid in the machine from flowing out from between the housing
10
and the rotating shaft
20
to the outside of the machine. At the sealing elements
34
, rotating force of the rotating shaft
20
is transmitted to the mating ring
344
via the shaft sleeve
33
, the collar
346
, the holder
342
, and the pin
342
a
. Here the shaft sleeve
33
is fixed to the rotating shaft
20
by the setscrew
332
. The collar
346
is adapted drivingly to engage with an inside cutout end
33
c
via a bin
346
a
. The holder
342
is connected by the bolt
345
. The pin
342
a
is provided on the holder
342
.
However, according to the above-described mechanical seal
30
, the mating ring
344
of the rotating side is constituted to fit to the ring-like recessed part of the holder
342
. Therefore, the size in the radial direction of the sealing elements
34
becomes in large. Accordingly, the large inner diameter of the housing
10
in the pump is necessary, which causes the large size of the whole machine. Further, the packing
343
is necessary for sealing between the mating ring
344
and the holder
342
. Therefore, this packing
343
needs high costs because of the large diameter.
Moreover, concerning the sealing elements
34
, the pin
342
a
and the cutout
344
a
are necessary for the holder
342
and the mating ring
344
as a rotation transmitting means. The collar
346
, the bolt
345
, the spacer
347
, and the pressing ring
348
or the like are necessary for the holder
342
as a fixing means in the axial direction. The pin
346
a
and the cutout part
33
c
are necessary for the collar
346
and the shaft sleeve
33
as a rotation transmitting means. Thus, these elements had complement forms and structures. Therefore, attachment work is so complicated that it takes long time, since the sealing elements
34
have the large number of elements.
Moreover, the sealing elements
34
need the large number of elements. If a few errors of the size or in attachment work were accumulated, the slide and contact position of the mating ring
344
largely slips off relative to the seal ring
322
, even if the attachment position of the shaft sleeve
33
is exact relative to the rotating shaft
20
. This leads possibly to generate large errors for the slide surface pressure.
SUMMERY OF THE INVENTION
The main object of the invention is to decrease the number of elements or parts to be used.
Another object of this invention is to provide a mechanical seal that can achieve its miniaturization and easy and rapid attachment work.
A mechanical seal according to one mode of this invention comprises a fixed ring connected in a sealed state to the housing and having a forcing means that is forced in an axial direction; a rotating ring having a slide part and an engaging part, wherein the slide part faces and slidably contacts with the fixed ring, and wherein the engaging part is formed for adapting drivingly to engage in a concave-convex manner; and a shaft sleeve fitted one end part in the sealed state to the rotating ring, holding the rotating ring in the axial direction, having a stop part adapted drivingly to engage with the engaging part without relative rotation, and fitted and stopped to the rotating shaft in the sealed state.


REFERENCES:
patent: 2247505 (1941-07-01), Kohler
patent: 2650841 (1953-09-01), Meyer
patent: 3117793 (1964-01-01), Hauser et al.
patent: 3410566 (1968-11-01), Wiese
patent: 3746

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