JP2004270777A - Lip type seal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lip type seal that can be used in a refrigerator using carbon dioxide or the like as a cooling medium and has a seal lip section with high wear resistance suitable for sealing the high-pressure gas. <P>SOLUTION: The lip type seal is formed by filling a rubber-made seal lip section with carbon fiber. The seal includes at least 15 wt% or more of carbon fiber filled in the seal lip section oriented to the angle 70-90° with respect to the rotational direction of a shaft, especially a compressor shaft. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a lip seal. More specifically, the present invention relates to a lip-type seal in which a rubber seal lip portion is filled with carbon fiber.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a compressor has been used to compress a refrigerant such as CFCs charged in a refrigeration circuit of an air conditioner, and a lip-type high-pressure seal has been used as a shaft seal of the compressor. In recent years, the destruction of the ozone layer of fluorocarbon gas as a refrigerant and environmental destruction due to global warming have become a problem, and the use of hydrocarbons, ammonia, carbon dioxide, and the like as refrigerants instead of fluorocarbon gas has been studied.
[0003]
Among them, carbon dioxide is liquefied relatively easily and has very low toxicity, and is considered to be a preferable refrigerant in terms of safety and prevention of pollution. However, a problem that must be overcome in putting a refrigerant machine using carbon dioxide as a refrigerant into practice is that the shaft seal of the compressor is exposed to high pressures that are inexperienced in the field of fluid seals.
[0004]
In a refrigerant circuit using, for example, Freon R-134a as the refrigerant, the pressure of the refrigerant stays in a range of about 0.4 to 1.4 MPa, whereas in a refrigerant circuit using carbon dioxide, the refrigerant enters the compressor. Carbon dioxide is assumed to be in a very high pressure range as a refrigerant gas of about 4 to 12 MPa. In addition, the temperature of the use environment, the number of rotations of the shaft, and the like also become higher in temperature and speed as compared with the related art.
[0005]
Thus, it is expected that the shaft seal of the compressor will slide under extremely severe conditions of high pressure, high temperature and high speed. In addition, when carbon dioxide is used as the refrigerant, the effect of the lubricating oil disappears as the rotation speed increases, the solid state between the lip and the shaft becomes almost solid, and the sliding heat increases due to high pressure, high temperature and high speed sliding. And increased wear. Therefore, the rubber material as the seal lip material is excessively worn by sliding under severe conditions, and the sealing function is greatly reduced.
[0006]
In order to solve such a problem, a hydrogenated nitrile rubber composition containing carbon black and other fillers in a total amount of about 120 parts by weight or more per 100 parts by weight of a hydrogenated nitrile rubber (hydrogenated NBR) is disclosed in the present application. It has been proposed by humans (Japanese Patent Application Laid-Open No. 2002-80639), and when carbon fiber is used as another filler, a rubber material excellent in wear resistance and low sliding heat generation is obtained. When this rubber material is used as a seal lip material for compressor-shaft sealing, good sealing performance is exhibited, but further improvement in wear resistance is required for maintaining sealing performance for a long period of time.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a lip seal having a highly wear-resistant seal lip portion that can be used in a refrigerator using carbon dioxide or the like as a refrigerant and is suitable for sealing high-pressure gas. It is in.
[0008]
[Means for Solving the Problems]
An object of the present invention is to provide a lip-type seal in which a rubber seal lip is filled with carbon fiber, wherein at least 15% by weight or more of the carbon fiber filled in the seal lip is rotated by a shaft, particularly a compressor shaft. This is achieved by a lip-type seal characterized in that it is contained in a state oriented at an angle of 70 to 90 ° to the direction.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
For example, a lip-type high-pressure seal includes an annular metal casing and an annular lip seal fixed to the casing, and the lip seal can be vulcanized and formed from various rubbers. Hydrogenated nitrile rubber compositions as described, i.e., carbon black (about 30-100 parts by weight) and other fillers (e.g., graphite about 100 parts by weight per 100 parts by weight of hydrogenated nitrile rubber). 10 to 60 parts by weight and about 5 to 60 parts by weight of carbon fiber).
[0010]
The vulcanized seal lip is filled with carbon fiber together with graphite, and at least 15% by weight, preferably 25% or more of the carbon fiber filled in the seal lip is filled with a compressor shaft or the like. Included in a state of being oriented at an angle of 70 to 90 ° with respect to the rotation direction of the shaft (the sliding surface is photographed with an SEM or a digital microscope and the orientation angle is measured using image analysis software). . However, the oriented carbon fiber is horizontal to the sliding surface (substantially 0 ° in the lip thickness Z-axis direction, that is, two-dimensionally substantially horizontal to the sliding surface). Is preferred.
[0011]
As described above, the seal lip material in which the carbon fibers are oriented at an angle perpendicular to or close to the rotation direction of the compressor shaft is compared with the seal lip material parallel or randomly oriented in the rotation direction of the compressor. Since the amount of wear is small by about 20 to 30%, even under severe sliding conditions such as high pressure, high temperature and high speed, it is possible to exhibit good sealing performance over a long period without excessive wear.
[0012]
The carbon fiber is a general pitch-based or PAN-based carbon fiber having a fiber diameter of about 1 to 20 μm, preferably about 5 to 15 μm, and a fiber length of about 0.01 to 1 mm, preferably Those having a thickness of about 0.03 to 0.5 mm are used.
[0013]
Controlling the orientation of the carbon fiber in such a state is performed by the following method. The rubber material is discharged from the roll in a sheet shape, and the carbon fibers are oriented in the sheet discharging direction. Next, the rubber material is cut out and set in a mold in accordance with the orientation direction of the carbon fiber on the sample sliding surface, and a sample is produced by compression molding.
[0014]
More specifically, this is performed according to the method shown in FIG. In this method, first, a rubber material 11 having a thickness of, for example, 2 mm is taken out from a roll in a sheet shape, and at this time, the carbon fibers 12, 12 ',. Next, the portion 13 having a width of 1.5 mm is cut in a direction perpendicular to the extending direction, and is wound into a spiral shape 14 having a height of 2 mm (b). This is placed on a frusto-conical mold 15 (c) and compression-molded to obtain a lip-type seal 18 having a frusto-conical seal lip 17 having a perforated portion 16 formed therein. (D) so as to be in sliding contact with the shaft 20 on the sliding surface 19 of FIG. As schematically shown in FIG. 1, the carbon fibers are largely oriented in a direction perpendicular to the rotation direction of the shaft.
[0015]
The lip seal obtained in this manner is used by being attached to a shaft, particularly a compressor shaft having a large problem of wear. In this case, the rubber seal lip is annular and used by being fixed to the annular casing. FIG. 7 (Example; a direction perpendicular to the sliding direction) and FIG. 8 (Comparative example; a direction parallel to the sliding direction) show this embodiment. Is a resin ring, 25 is a metal annular casing, 27 is a rubber seal lip, and 28 is a lip seal.
[0016]
【The invention's effect】
The lip-type seal according to the present invention can further reduce the amount of wear by positively controlling the orientation state of the carbon fiber filled in the seal lip portion, so that the relatively rotating shaft, particularly the compressor, When applied to a lip-type seal for providing a fluid seal between the shaft and the housing, the seal lip has a high wear resistance even when used under extremely high fluid pressure, as a fluid seal between the shaft and the housing Properties can be imparted. For this reason, it is also effectively used as a lip-type seal for gasoline engine specifications that slides under high pressure, high temperature and high speed conditions. This lip seal has a rubber seal lip portion formed in an annular shape, and is generally used by being fixed to an annular metal casing.
[0017]
【Example】
Next, the present invention will be described with reference to examples.
[0018]
Example 100 parts by weight of hydrogenated NBR (Zetpol 2000 from Zeon Corporation) SRF carbon black 90%
Pitch-based carbon fiber (Osaka Gas Chemical Products; 45〃
(Fiber diameter 10 μm, fiber length 0.06 mm)
Graphite (Nidec Carbon Products) 15〃
Anti-aging agent (Uniroyal product # 445) 2 〃
Organic peroxide (Nippon Oil & Fat Products Park Mill D) 6〃
Co-crosslinking agent (JSR product B3000) 5〃
Each of the above components was kneaded with a 10-inch roll, and the kneaded product was compression-molded at 180 ° C. according to the method shown in FIG. 5 to vulcanize and form a seal lip having a seal lip portion.
[0019]
FIG. 1 is a schematic diagram showing the orientation distribution of carbon fibers in the shaft rotation direction of the sliding surface of the seal lip portion, and an orientation distribution histogram showing the frequency of the angle (measured by the above method) with respect to the rotation direction. The angle 0 with respect to the rotation direction is 0 °, and for example, 0 ° <θ ≦ 10 ° is shown as an angle of 0 to 10 °. As can be seen from this result, the amount of carbon fiber oriented at an angle of 70 to 90 ° with respect to the rotation direction of the compressor shaft is 53%, and the carbon fiber is perpendicular to the rotation direction of the compressor shaft. Tend to be oriented.
[0020]
Comparative Example 1
In the example, as shown in FIG. 2, a seal lip in which the amount of carbon fiber oriented at an angle of 70 to 90 ° with respect to the rotation direction of the compressor shaft is 8% was vulcanized. In this case, there is a tendency that the carbon fibers are oriented parallel to the rotation direction of the compressor shaft.
[0021]
Comparative Example 2
In the example, as shown in FIG. 3, a seal lip in which the amount of carbon fiber oriented at an angle of 70 to 90 ° with respect to the rotation direction of the compressor shaft is 13% was vulcanized. In this case, there is a tendency that the carbon fibers are randomly oriented in the rotation direction of the compressor shaft. This corresponds to the orientation state at the seal lip described in the prior art.
[0022]
Controlling the orientation of the carbon fibers in the state as in Comparative Examples 1 and 2 is performed according to the method shown in FIG. In this method, first, a rubber material 11 having a thickness of 2 mm is taken out from a roll in the form of a sheet. At this time, the carbon fibers 12, 12 ',. a). Next, a part 13 'having a width of 1.5 mm is cut in a direction parallel to the parting direction, and the part 13' is wound in a spiral shape 14 '(b), placed on a mold 15 (c), and compression-formed to form a perforated part. A step (d) of forming a lip-type seal 18 ′ having a seal lip portion 17 ′ with a bore 16 and mounting the lip type seal 18 ′ in sliding contact with the shaft 20 on a sliding surface 19 ′ of the seal lip portion 17 ′ is as follows. This is performed in the same manner as in FIG. The carbon fibers are largely oriented in a direction parallel to the rotation direction of the shaft, as schematically shown in FIGS.
[0023]
With respect to the seal lips of the above Examples and Comparative Examples, a rotation test was performed for 1 hour under the conditions of a peripheral speed of 1 m / sec and a surface pressure of 5.5 MPa, and the amount of abrasion relative to the amount of vertically oriented carbon fibers was determined. The measurement was performed, and the results are shown in the graph of FIG.
[0024]
From this result, by orienting the carbon fiber in the direction perpendicular to the rotation direction of the compressor shaft, compared to those having a seal lip portion oriented in a parallel direction or a seal lip portion randomly oriented, It can be seen that the wear amount is reduced by 20 to 30%. In other words, even under extremely severe sliding conditions of high load such as high pressure, high temperature and high speed, the seal performance life is improved so that good seal performance is exhibited for a long period of time without excessive wear.
[Brief description of the drawings]
FIG. 1 is a histogram and a schematic diagram of an orientation distribution of carbon fibers in a lip seal portion of an example.
FIG. 2 is a histogram and a schematic diagram of an orientation distribution of carbon fibers in a lip seal portion of Comparative Example 1.
FIG. 3 is a histogram and a schematic diagram of an orientation distribution of carbon fibers in a lip seal portion of Comparative Example 2.
FIG. 4 is a graph showing the relationship between the amount of carbon fiber oriented in the vertical direction and the amount of wear in the rotation test on the seal lips of the example and comparative examples 1 and 2.
FIG. 5 is a manufacturing process diagram of a lip-type seal having a seal lip portion in which carbon fibers are largely oriented in a direction perpendicular to a rotation direction of a shaft in Examples.
FIG. 6 is a manufacturing process diagram of a lip-type seal having a seal lip portion in which carbon fibers are largely oriented in a direction parallel to a rotation direction of a shaft in each comparative example.
FIG. 7 is a center line sectional view showing a state where the annular rubber seal lip of the embodiment is attached to an annular metal casing.
FIG. 8 is a center line sectional view showing a state in which an annular rubber seal lip portion of a comparative example is attached to an annular metal casing.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Seal lip rubber 2,12,22 Carbon fiber 17,17 ', 27 Rubber seal lip 18,18', 28 Lip type seal 19,19 'Sliding surface 20 Shaft 25 Ring metal casing

Claims (6)

In a lip-type seal in which a rubber seal lip portion is filled with carbon fiber, at least 15% by weight or more of the carbon fiber filled in the seal lip portion is at an angle of 70 to 90 ° with respect to the rotation direction of the shaft. A lip-type seal which is contained in an oriented state. 2. The lip seal according to claim 1, wherein the carbon fiber is two-dimensionally and substantially horizontally oriented with respect to the sliding surface such that the carbon fiber is substantially at 0 [deg.] To the lip thickness Z-axis direction. 2. The lip seal according to claim 1, wherein the rubber seal lip filled with the carbon fiber is obtained by vulcanizing a hydrogenated nitrile rubber composition. Composition in which the hydrogenated nitrile rubber composition contains 30 to 100 parts by weight of carbon black, 10 to 60 parts by weight of graphite, and 5 to 60 parts by weight of carbon fiber in a total amount of 120 parts by weight or more per 100 parts by weight of the hydrogenated nitrile rubber. The lip-type seal according to claim 3, which is a material. 3. The lip seal according to claim 1, wherein the shaft is a compressor shaft. The lip seal according to claim 1 or 5, wherein the rubber seal lip is annular and used by being fixed to an annular metal casing.

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