Rotary joint assembly

Details Rotary joint assembly Rotary joint assembly

1999-05-21

2001-02-13

Melius, Terry Lee (Department: 3628)

Seal for a joint or juncture

Seal between relatively movable parts

Relatively rotatable radially extending sealing face member

C277S590000, C277S603000

Reexamination Certificate

active

06186509

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to a rotary joint assembly for use in a fluid pipeline.
DESCRIPTION OF THE PRIOR ART
A rotary joint assembly for fluid pipeline is mounted to, for example, a polishing apparatus which uses the CMP (Chemical Mechanical Polishing) method for polishing a silicon wafer surface. The surface polishing apparatus polishes the surface of a silicon wafer
102
in the following manner. A polishing pad
103
is brought into contact with the surface of the wafer
102
placed on a rotating table
101
, as shown in FIG.
3
. The polishing pad
103
is rotated and horizontally moved back and forth while a pump
104
delivers a jet of polishing fluid, such as of a fluid slurry, between the wafer surface and the polishing pad whereby the wafer is polished.
In the surface polishing apparatus of this type, a rotating shaft
105
of the rotating table
101
includes a fluid feed passage
106
for feeding a cleaning or temperature regulating liquid and compressed air for drying, to the wafer
102
and the rotating table
101
after completion of the polishing work, and a fluid recovery passage
107
for recovering the cleaning or temperature regurating liquid supplied to the silicon wafer
102
and the rotating table
101
. The fluid feed passage
106
is connected to a fluid feeding pump P
10
via a rotary joint assembly
108
. On the other hand, the fluid recovery passage
107
is connected to a fluid recovering pump P
20
via the rotary joint assembly
108
.
As shown in
FIG. 4
, the rotary joint assembly
108
has a construction in which a rotator
110
is rotatably retained in a hollow interior of the housing
109
. The housing
109
includes a first flow opening
109
a
communicated with the fluid feeding pump P
10
, and a second flow opening
109
b
communicated with the fluid recovering pump P
20
. Extended through the rotator
110
are a first flow passage
111
for communication between the first flow opening
109
a
in the housing
109
and the fluid feed passage
106
in the rotating shaft
105
(FIG.
3
), and a second flow passage
112
for communication between the second flow opening
109
b
in the housing
109
and the fluid recovery passage
107
in the rotating shaft
105
. An annular space to be formed between the housing
109
and the rotator
110
is hermetically defined with O-rings
113
.
Unfortunately, the above rotary joint assembly
108
suffers a lowered durability because the O-rings
113
, in sliding contact with the rotator
110
, are prone to wear. Further, the use of high-pressure fluid is not permitted because the O-ring-sealed gap falls short of ensuring the air-tightness.
As a solution to this problem, there is proposed a rotary joint assembly employing a double-mechanical seal for sealing the gap between the housing
109
and the rotator
109
. As shown in
FIG. 5
, this rotary joint assembly has a first rotary seal ring
121
axially movably mounted to a lower end portion of the rotator
110
. Opposite to the first rotary seal ring
121
, a first stationary seal ring
122
is secured to the housing
109
. A first helical spring
123
presses the first rotary seal ring
121
into intimate contact with the first stationary seal ring
122
. The rotary joint assembly further has a second rotary seal ring
124
secured to place near an upper end of the rotator
110
. Opposite to the second rotary seal ring
124
, a second stationary seal ring
125
is axially movably mounted to the housing
109
. A second helical spring
126
biases the second stationary seal ring
125
into intimate contact with the second rotary seal ring
124
.
However, the above rotary joint assembly has the construction in which the first helical spring
123
is disposed at the lower end of the first seal ring
121
, and the second helical spring
126
is interposed between the first and second stationary seal rings
122
,
125
, and hence, the housing
109
and the rotator
110
must have great axial lengths. As a result, the assembly is great in size.
OBJECT AND SUMMARY OF THE INVENTION
In view of the foregoing, an object of the present invention is to provide a rotary joint assembly which ensures the air-tightness and durability and accomplishes the downsizing of the assembly.
For achieving the above object, the rotary joint assembly according to the present invention comprises:
a hollow housing including a flow opening;
a rotator including a flow passage communicated with the flow opening and being rotatably retained in a hollow interior of the housing; and
a double-mechanical seal for hermetically defining a space to be formed between the housing and the rotator,
the double-mechanical seal including:
a pair of rotary seal rings axially movably mounted to the rotator as spaced from each other by a predetermined distance;
a pair of stationary seal rings retained by the housing as sandwiching the rotary seal rings therebetween;
a stopper ring interposed between the pair of rotary seal rings as spaced from the respective rotary seal rings, the stopper ring inhibiting relative rotation between the rotary seal rings and the rotator and including a through-hole for communication between the flow opening and the flow passage; and
a spring interposed in a space between the stopper ring and each of the rotary seal rings and biasing each of the rotary seal rings into intimate contact with the corresponding stationary seal ring.
According to the rotary joint assembly of the above construction, the stopper ring is interposed between the pair of rotary seal rings. Interposed in the space between the stopper ring and each rotary seal ring is the spring for biasing each rotary seal ring. Thus, the whole length of the double-mechanical seal is reduced. Accordingly, the housing and the rotator have reduced axial lengths, which, in turn, provide the corresponding downsizing of the assembly. In addition, the hermetically sealed structure using the mechanical seal ensures high air-tightness and durability of the assembly.
In the above rotary joint assembly, the aforesaid spring is preferably a laminated spring. The use of such a spring ensures a desired elastic-biasing force and also accomplishes the reduction of the axial length of the spring. Thus, the housing and the rotator are even further reduced in the axial lengths thereof.


REFERENCES:
patent: 5199748 (1993-04-01), Jung et al.
patent: 41 03 376 (1992-08-01), None
patent: 1-269727 (1989-10-01), None

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