JPH0557525U - Lip seal - Google Patents

Abstract

(57) [Summary] [Purpose] To allow the lip member 13 to use fluororubber having low heat resistance but low freon resistance. [Structure] The lip member 13 is a main body 131 made of PTFE.
And a structure in which the synthetic rubber thin film 132 adhered to the inner peripheral surface of the inner diameter portion 131a of the main body 131 has a structure in which Freon in the sealed space A does not easily penetrate into the synthetic rubber thin film 132. Fluorine rubber can be used for the synthetic rubber thin film 132.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 TECHNICAL FIELD The present invention relates to a lip-type seal, in which freon, which is a refrigerant of a refrigerator, is sealed.

[0002]

[Prior Art]

 2. Description of the Related Art Conventionally, as a shaft sealing device used in, for example, a car cooler compressor, there is a lip type seal as shown in FIG. This lip-type seal has a base portion having an outer diameter on the inner side of the sealed space A on the inner periphery of the metal case 1 which is tightly fitted and fixed to the mounting portion 6a formed in the shaft hole of the housing 6 via the O-ring 7. A rubber-made lip member 2 made of nitryl rubber (NBR) reinforced with a metal ring 3, a PTFE lip member 4 having heat resistance on the anti-seal space (atmosphere) B side, and the PTFE lip member 4 are provided. The metal backup ring 5 supported from the anti-seal space B side is held in a state where the outer diameter portions thereof are in close contact with each other, and the inner diameter portions 2a, 4a of the lip members 2, 4 become the outer peripheral surface of the shaft 8. Airtight sliding contact is made to prevent the refrigerant and refrigerating machine oil in the sealed space A from leaking to the anti-sealed space B, that is, the atmosphere.

[0003]

[Problems to be solved by the device]

In the above lip-type seal, the pressure in the sealed space A during normal operation is about 1 kg / cm ² to 4 kg / cm ² , and it is used for a compressor having relatively loose operating conditions represented by a so-called swash plate type. There were many. However, recent cooler compressors tend to increase the temperature of the sealed space A (compression chamber) due to downsizing and speeding up, and the newly developed variable displacement compressor is Since the pressure in the space A (compression chamber) increases, the amount of heat generated by the sliding of the rubber-made lip member 2 and the shaft 8 on the sealed space A side tends to increase accordingly.

However, according to the above-mentioned conventional lip-type seal, the nitrile rubber, which is the material of the rubber-made lip member 2, emphasizes oil resistance, freon resistance, and wear resistance, and therefore high temperature atmosphere conditions and high speed Under high heat generation conditions due to sliding, rubber elasticity deteriorated, and cracks and leakage due to abnormal wear were found to occur.

Therefore, in order to improve the heat resistance, it is desirable to use fluorine rubber as the material of the rubber-made lip member 2. However, fluororubber has a high permeability to Freon, which is a refrigerant in the sealed space A. Since it is high, a large amount of freon easily penetrates into the rubber, and when the ambient temperature rises while the freon penetrates, the saturated vapor pressure of freon in the rubber atmosphere increases and cracks due to foaming occur in the rubber lip member 2. In practice, fluororubber could not be used because it would occur.

The lip-type seal of the present invention has been made in view of the above points, and an object thereof is to make it possible to use fluororubber having excellent heat resistance for the lip member.

[0007]

[Means for Solving the Problems]

 In order to solve the above problems, a lip-type seal according to the present invention is a lip in which an inner peripheral portion of a metal case, which has an inner diameter portion slidably contacting an outer peripheral surface of a shaft, is bent and extends toward a sealed space, and is integrally held. In the mold seal, the lip member is composed of a PTFE main body and a synthetic rubber thin film adhered to the inner peripheral surface of the inner diameter portion of the main body.

[0008]

[Action]

 According to the above structure, the main body made of PTFE, which is in contact with the sealed space, has excellent heat resistance and has low penetrability of freon. On the other hand, the synthetic rubber thin film adhered to the inner surface of the inner diameter of the main body firmly adheres to the outer peripheral surface of the shaft due to its elasticity, and the end surface exposed from the inner diameter at the tip of the main body slightly contacts the sealed space. However, since the penetration of Freon in the sealed space is suppressed, even if fluorine rubber with high heat resistance is used as the material of the synthetic rubber thin film, it is possible to prevent the penetration of a large amount of Freon and the resulting foaming phenomenon of rubber. You can

[0009]

【Example】

 FIG. 1 shows an embodiment of a lip-type seal of the present invention used as a shaft sealing device for a compressor for a cooler. Reference numeral 11 denotes a metal outer case, and 12 denotes a caulked fixing to the inner circumference of the outer case 11. It is an inner metal case with an L-shaped cross section. Inner diameter flanges 11a and 12a of the outer case 11 and the inner case 12 are axially opposed to each other, and a lip member 13 whose inner diameter is bent and extends toward the sealed space A is sandwiched between the flanges 11a and 12a. It is worn.

The lip member 13 is composed of a PTFE main body 131 and a fluororubber thin film 132 adhered with an adhesive to the entire back surface including the inner peripheral surface of the inner diameter portion 131 a of the main body 131. Specifically, for example, the thickness of the PTFE main body 131 is about 1.0 mm, while the thickness of the fluororubber thin film 132 is 0.1 mm to 0.5 mm.

In the lip-type seal having the above-described structure, the outer case 11 is tightly fitted to the mounting portion 14 a formed in the shaft hole of the housing 14 via the O-ring 15, and is fixed by the snap ring 16 while the lip member 13 is fixed. The inner peripheral surface of the inner peripheral portion of the inner peripheral surface, that is, the inner peripheral portion 132a of the fluororubber thin film 132 is brought into airtight sliding contact with the outer peripheral surface of the shaft 17, so that the refrigerant and the refrigerating machine oil in the sealed space A are transferred to the atmosphere in the anti-sealed space B. It prevents it from leaking.

The inner diameter flange 11 a of the outer case 11 has a function of backing up the lip member 13 from the anti-sealing space B side and restricting the deformation of the lip member 13 due to the pressure of the sealing space A. The outer diameter portion 132c is in close contact with the inner diameter flange 11a to maintain airtightness between the outer case 11 and the lip member 13. Further, since the O-ring 15 that seals between the housing 14 and the outer case 11 does not generate frictional heat unlike the moving part, it does not need to have such high heat resistance, and therefore the heat resistance is not required. Nitrile rubber, which has a low but low Freon permeability, is used.

Since the PTFE main body 131 has a higher Young's modulus than the fluororubber thin film 132, the amount of diameter reduction deformation due to the pressure in the sealed space A is small, and therefore, the outer circumference of the shaft 17 of the lip member 13 at high pressure is small. The increase in sliding heat generation due to the increase in the contact width with the surface is suppressed. On the contrary, since the PTFE main body 131 has a high Young's modulus, the tightening force, that is, the tightening force with respect to the shaft 17 becomes large. Therefore, in order to reduce the sliding load due to such a tightening force, at least the PTFE body 131 is used. The inner diameter portion 131a of the main body 131 has a thin structure with a thickness of about 1.0 mm. It should be noted that this wall thickness may be appropriately set in consideration of use conditions such as the pressure in the sealed space A.

Although the PTFE main body 131 has high heat resistance and does not allow the penetration of freon, the fluorine rubber thin film 132 has a distal end surface 132b of the inner diameter portion 132a from the inner tip end of the PTFE main body 131 to the sealed space A. Since it is exposed, Freon in the sealed space A penetrates from the tip surface 132b. However, according to the configuration of the present embodiment, the thickness of the fluororubber thin film 132, that is, the exposed width t is as small as 0.1 mm to 0.2 mm, so that the permeation amount of freon can be suppressed to a very small amount. Also, due to its thin wall, even if the permeated freon vaporizes at high temperature or low pressure, the vaporized freon is released from the rubber surface, and the foaming phenomenon does not occur in the rubber atmosphere. Despite the use of fluororubber that allows Freon to easily penetrate, it is possible to prevent a large amount of Freon from penetrating and the resulting foaming phenomenon.

The present invention is not limited to the structure of the illustrated embodiment. For example, the thin film 132 made of fluorine rubber is attached only to the inner peripheral surface of the inner diameter portion 131 a of the PTFE main body 13. It is also possible to have a structure.

[0016]

[Effect of the device]

 As described above, according to the present invention, since the synthetic rubber thin film is adhered to the inner peripheral surface of the PTFE main body where freon does not penetrate, not only the penetration of freon in the sealed space is suppressed. However, since the infiltrated Freon vaporizes at high temperatures to prevent foaming in the rubber atmosphere, it is possible to use fluororubber with low heat resistance but high Freon resistance for the synthetic rubber thin film. It is possible to satisfy both the requirements of improving heat resistance and preventing the seal from breaking due to the foaming phenomenon.

[Brief description of drawings]

FIG. 1 is a half sectional view showing an embodiment of the present invention.

FIG. 2 is a half-cut sectional view showing an example of a conventional structure.

[Explanation of symbols]

 11 Outer Case (Metal Case) 12 Inner Case (Metal Case) 13 Lip Member 131 PTFE Main Body 131a, 132a Inner Diameter Part 132 Fluorine Rubber Thin Film (Synthetic Rubber Thin Film) A Sealed Space B Anti-sealed Space

Claims (1)

[Scope of utility model registration request] 1. A lip-type seal integrally holding, on an inner circumference of a metal case, a lip member whose inner diameter portion slidably contacting an outer circumferential surface of a shaft is bent and extends toward a sealed space, wherein the lip member is a main body made of PTFE. A lip-type seal, comprising: a synthetic rubber thin film adhered to an inner peripheral surface of an inner diameter portion of the main body.