Seal for a joint or juncture – Seal between relatively movable parts – Circumferential contact seal for other than piston
Reexamination Certificate
2001-03-09
2003-04-08
Knight, Anthony (Department: 3676)
Seal for a joint or juncture
Seal between relatively movable parts
Circumferential contact seal for other than piston
C277S346000, C277S353000, C277S562000
Reexamination Certificate
active
06543786
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to installation structure of a lip type seal which seals a circumferential surface of a rotary shaft of various sorts of equipment.
PRIOR ART
In the prior art, as an installation structure of a lip type seal, ones as shown in FIG.
15
and
FIG. 16
are known. In these figures, reference numeral
101
designates a shaft hole housing of a equipment such as a compressor of a refrigerator in an air conditioner, numeral
102
designates a rotary shaft inserted in an inner circumference of the shaft hole housing
101
, and numeral
200
designates a lip type seal which is installed to a seal installation part
101
a
formed on the inner circumferential surface of the shaft hole housing
101
and seals the shaft circumference of the rotary shaft
102
.
The lip type seal
200
shown in
FIG. 15
is provided on an inner circumference of an annular casing
201
made of metal with a main seal lip
202
made of rubber material, a resin seal lip
203
made of a low friction resin material and arranged at the rear side of the main seal lip
202
, and a rear surface support ring
204
made of metal and arranged further at the rear side of the resin seal lip
203
. The casing
201
is tightly fitted to the seal installation part
101
a
of the shaft hole housing
101
through an O-ring
205
made of rubber material. The inner circumferential part of the seal lips
202
,
203
curved and extending to the side of a sealed space S
1
within the machine is closely contacted with the outer circumferential surface of the rotary shaft
102
.
Also in the lip type seal
200
shown in
FIG. 16
, an outer circumferential part of a main seal lip
202
is joined integrally with a casing
201
. The casing
201
is tightly fitted to an inner circumferential surface of a seal installation part
101
a
of a shaft hole housing
101
through a close contact seal part
206
formed in continuation with the outer circumferential part of the main seal lip
202
made of rubber material. Other parts are constituted substantially in a similar manner to FIG.
15
.
In recent years, a refrigerant circulated in a refrigeration cycle of an air conditioner has been changed to freon R134a not including chrorine which destroys an ozone layer in the stratosphere. In the freon R134a, a warming coefficient of absorbing a long wave (infrared) radiation from the ground surface and bringing the greenhouse effect is large. That is, the freon R134a is a greenhouse effect gas which may bring the earth warming even if quite little amount leaks in the air. Therefore, as a refrigerant as above described, changing is being studied from R134a to CO
2
(carbon dioxide) in which a warming coefficient is relatively small.
The lip type seal in the conventional structure as above described, is excellent in the gas resisting transmission property for the freon gas and exhibits a good seal performance. In CO
2
, however, since the transmission property for rubber material is high, when such lip type seal is used in a shaft seal device of a compressor of a refrigerator where CO
2
is a refrigerant, refrigerant CO
2
of high pressure compressed within the machine easily transmits the O-ring
205
or the close contact seal part
206
made of rubber material and leaks to the outside A of the machine.
SUMMARY OF THE INVENTION
An object of the present invention is to provide installation structure of a lip type seal which can exhibit a seal performance excellent for CO
2
.
According to one mode of the present invention, the equipment has a rotary shaft and a housing, and a lip type seal is installed between the housing and the rotary shaft. The installation structure of the lip type seal has a casing having an annular outer circumferential part, a seal lip which is held to the inside of or held integrally with the annular outer circumferential part of the casing and seals the circumferential surface of the rotary shaft, a main gasket provided between the outside of the annular outer circumferential part of the casing and the inner circumferential surface of the housing so as to prevent the leakage of CO
2
, and a sub-gasket provided at the downstream of CO
2
which leaks from the main gasket so as to prevent CO
2
from leaking to the side of the outer atmosphere. It is preferable that the sub-gasket is made of a material having a CO
2
permeability coefficient smaller than that of rubber material. The sub-gasket is arranged between the annular outer circumferential part of the casing and the inner circumferential surface of the housing.
According to another mode of the present invention, the sub-gasket is small in thickness in the, direction orthogonal to the gas transmission direction in comparison with the main gasket.
It is preferable that the sub-gasket is arranged between a rear plate extending from the annular outer circumferential part of the casing toward the rotary shaft and an opposite inner surface of the housing being opposite to the rear plate. A great portion of the rear plate extends substantially in the orthogonal direction to the axial center of the rotary shaft.
The sub-gasket is a ring such as an O-ring, a square ring or a hollow metal ring.
According to the further other mode of the present invention, the sub-gasket is a rubber sheet. For example, the sub-gasket is a rubber sheet arranged in a belt-shaped groove formed in the opposite inner surface of the housing. Otherwise, the sub-gasket is a rubber sheet provided at a rear surface of the rear plate.
The main gasket is formed in continuation with the seal lip. Otherwise, the main gasket is provided separately from the seal lip.
The main gasket is an O-ring or a close contact seal part.
In the further still other mode of the present invention, the sub-gasket is a ring made of a material (for example, resin) having a CO
2
transmission coefficient (CO
2
leakage coefficient) smaller than that of rubber material of an O-ring being the main gasket.
Also, the sub-gasket may be that having a small CO
2
transmission amount by making the thickness small in the direction orthogonal to the gas transmission direction in comparison with the main gasket (for example, that in a sheet shape).
A structure according to still another mode of the present invention is an installation structure of a lip type seal, where an outer circumferential part of a seal lip is held to or provided integrally with an annular case, and the case is tightly fitted to an inner circumferential surface of a housing of an equipment through a main gasket provided in continuation with or separately from the seal lip, and an inner circumferential part of the seal lip is closely contacted with the outer circumferential surface of a rotary shaft which is inserted in the inner circumference of the housing, characterized in that a sub-gasket made of a material having a CO
2
transmission coefficient smaller than that of rubber material is interposed between the case or the rear plate provided on the case and the opposite surface of the housing.
A structure according to still another mode of the present invention is an installation structure of a lip type seal, where an outer circumferential part of a seal lip is held to or provided integrally with an annular case, and the case is tightly fitted to an inner circumferential surface of a housing of an equipment through a main gasket provided in continuation with or separately from the seal lip, and an inner circumferential part of the seal lip is closely contacted with the outer circumferential surface of a rotary shaft which is inserted in the inner circumference of the housing, characterized in that a sub-gasket having the small thickness in the direction orthogonal to the gas transmission direction in comparison with the main gasket is interposed between the case or a rear plate provided in the case and the opposite surface of the housing.
A typical example of the equipment to which the present invention is applied, is a compressor of a refrigerator. The present invention can be applied also to other equipment.
In addition
Hayakawa Naoki
Matsumoto Takanobu
Osumi Shiro
Takayuki Imai
Takeshi Yamada
Eagle Industry Co. Ltd.
Jacobson & Holman PLLC
Knight Anthony
Peavey E
LandOfFree
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