JPH0238832B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is suitable for use in harsh environments where performance such as heat resistance, pressure resistance, chemical resistance, abrasion resistance, low friction, and ability to follow shaft runout is required. The present invention relates to a shaft sealing device equipped with a lip seal that is put to practical use under various circumstances, and is used, for example, to seal the rotating shaft of an open compressor.

[Conventional technology]

Conventional shaft seals that slide in contact with the rotating shaft to prevent fluid leakage have used synthetic rubber lip seals molded in molds, but rubber materials are generally heat-resistant and pressure-resistant. Due to poor performance such as heat resistance, chemical resistance, and abrasion resistance, it is used in atmospheres with refrigerant and refrigerant, such as automobile air conditioning compressors, which have a maximum temperature of 150℃ and a maximum pressure of 15Kg/ ^cm2. For this reason, mechanical seals are usually used. The mechanical seal usually has a rotating contact ring that is tightly fitted to a rotating shaft and a fixed contact ring that is tightly fitted to a fixed part, which are in contact with each other at their end faces, and the rotating contact ring is slid onto the fixed contact ring by a spring. This is a device that seals fluid by pressurizing the surfaces, and therefore the sliding surfaces are required to have a high degree of smoothness and are expensive.

Therefore, in recent years, shaft sealing devices with internal lip seals made of tetrafluoroethylene resin, which has excellent heat resistance, pressure resistance, chemical resistance, wear resistance, and friction resistance, have been used in various fields. In order to further improve its performance, various improvements have been made to the shape of the lip, the structure of its holding part, the combination of additives, etc. More specifically, there are those that minimize power and wear by increasing and decreasing the closing area of the lip in response to fluctuations in fluid pressure, or those that are devised so that the binding force of a garter spring changes (in practice). Kosho 43-
(No. 8828, Utility Model Publication No. 43-15626), and because tetrafluoroethylene resin is a material with poor elasticity and high rigidity compared to rubber such as synthetic rubber, its disadvantages can be overcome with soft elastic materials such as rubber. Complement by using together,
The soft elastic material is configured to reasonably respond to the rotational vibration of the rotating shaft and the movement of the lip portion that follows the eccentric movement.
(Japanese Utility Model Publication No. 17465, Japanese Utility Model Publication No. 1746-2578), or one in which the elasticity is increased by laminating thin-walled tetrafluoroethylene resin members and the ability to follow shaft runout is improved (Utility Model Publication No. 46-1701) Shaft seal devices equipped with various lip seals have been provided. Also,
Efforts have also been made to add metal powders such as copper-based alloys or iron-based alloys to tetrafluoroethylene resins as additives to improve the performance required for sealing materials or to add new materials.

[Problem that the invention seeks to solve]

In a shaft seal device that contacts the rotating shaft of a compressor or the like with its sliding surface to seal fluid, the lip seal cannot withstand and is exposed to oil liquid or gas, and when used continuously at high speed, the lip seal sliding part Due to frictional heat, the temperature becomes higher than the ambient temperature. For example, the atmospheric conditions for an automobile air conditioning compressor are such that the maximum temperature is
The temperature reaches 150℃, and the pressure of the sealed objects, in this case the refrigerant Freon gas and refrigeration oil, is
Depending on the operating conditions, the pressure is quite high, ranging from 0.3 to 15 Kg/cm ² , and the range of variation is large. For this reason, it is likely to use tetrafluoroethylene resin, which has excellent properties as a lip seal base material, but tetrafluoroethylene resin has poor elasticity and low rigidity compared to rubber such as rigid rubber. Many lip seals have been provided that are made of high-quality materials, and their drawbacks are compensated by the use of soft elastic materials such as rigid rubber, but all of them have complex structures, and also tend to soften and change shape at high temperatures, resulting in poor durability. The drawback is that it has poor sealing performance.

The purpose of the present invention is to provide a shaft sealing device equipped with a durable lip seal that maintains sufficient sealing performance even at high temperatures and high pressures and can be used even under harsh conditions such as in automobile air conditioning compressors. It has been done.

[Means for solving problems]

In order to solve the above-mentioned problem, the present invention provides a lip seal base material made by adding 3 to 10% by weight of graphite powder and 3 to 15% by weight of carbon fiber to tetrafluoroethylene resin, and a flange portion 12 is provided around the periphery. It has a flat disc-shaped sealing member 1 having a circular hole 1' in the center thereof, a cylindrical wall 21, and an annular wall 22 extending radially inward from one side edge of the cylindrical wall 21. Ring wall 22
The cylindrical part 2 is pressed to hold the mounting O-ring 31 in the O-ring groove 33 of the fixed part from the inner edge of the cylindrical part 2 outward in the axial direction.
3 and a holding ring 20 extending radially inward from the other side edge of the cylindrical wall 21, and the flange portion 12 brought into close contact with the inner surface of the ring wall 22. Abutting radial clamping portion 29
is press-fitted between the flange portion 12 and the clamping ring 24, and a press ring wall 27 and a press cylinder wall 28 are recessed on the outer periphery in order to press and hold the O-ring 30 against the flange portion 12 and the inner surface of the cylinder wall 21. The push ring 2
6, press-fit the core mold 6 into the circular hole 1' of the flat disc-shaped seal member 1 attached to the holding ring 20, and push the inner edge of the circular hole 1' to one side in the axial direction. A shaft sealing device was constructed in which the lip portion 13 was molded to form the lip seal 11.

[Effect]

In the shaft sealing device of the present invention having the above-mentioned contents, the lip seal base material is made of tetrafluoroethylene resin containing 3 to 10% by weight of graphite powder and 3 to 15% by weight of carbon fiber. In addition to the heat resistance, pressure resistance, chemical resistance, abrasion resistance, and friction resistance inherent in resin, it has the strength and durability required for mechanical parts, and is made from this seal base material. A lip portion 1 formed by pushing the inner edge of the circular hole 1' of the flat disc-shaped sealing member 1 to one side in the axial direction.
3, the lip seal 11 with the lip part 13 is heated due to the frictional heat generated when the lip part 13 is used in sliding contact with the rotating shaft and the contact with the sealed fluid.
The temperature of the lip 13 increases, thereby increasing the temperature of the lip 13.
By actively utilizing the restoring force that causes the rotor to return to its original flat disk shape, the rotating shaft is tightened, thereby suppressing the deterioration of sealing performance.

Further, the flange portion 12 of the flat disc-shaped seal member 1
is held firmly between the ring wall 22 of the holding ring 20 and the holding part 29 of the push ring 26, and
An O-ring 30 is pressed and held in an annular recess formed by the pressing ring wall 27 and the pressing cylindrical wall 28 of the pressing ring 26.
It is elastically compressed and held tightly.

Then, in a state where it is attached to a fixed part such as a compressor container, the seal line from the rotating shaft passes through the lip seal 11 and the O-ring 30 to the cylindrical wall 21 of the holding ring 20, and from the cylindrical part 23 of the holding ring 20. A seal line is formed that passes through the mounting O-ring 31 and reaches the side wall of the O-ring groove 33 of the fixing part.

〔Example〕

Next, the present invention will be further explained in detail based on embodiments shown in the accompanying drawings.

In the present invention, 3 to 10% by weight of graphite powder and 3 to 15% of carbon fiber are added to tetrafluoroethylene resin.
Using a sealing base material with improved mechanical strength and durability obtained by adding % by weight, a perforated flat disc-shaped sealing member is made from the sealing base material, and the inner edge of the flat disc-shaped sealing member is A lip is formed by protruding outward in a cylindrical shape under pressure or heating conditions, and due to the frictional heat caused by the lip sliding on the rotating shaft and the ambient temperature, the original flat circle is Utilizing the property of restoring to a plate shape, the lip part is added to the rotating shaft, allowing high temperatures,
The lip seal 11 is designed to maintain its sealing properties even under pressure, and the lip seal 11 is hermetically mounted within a retaining ring 20 having a specific structure.

Below, a method for manufacturing a lip seal in which graphite powder and carbon fiber are appropriately blended and added will be described in detail.

(a) A hollow cylindrical isodensity sealing base material made by adding graphite powder and carbon fiber to tetrafluoroethylene resin is prepared by a known method. In this case, the preferred blending ratio of additives is graphite powder: 5-10% by weight, carbon fiber: 5-10% by weight, and the total amount added is around 15% by weight, which is suitable for the shaft sealing device of an open compressor. It is the perfect sealing base material. The sealing base material is made of fine powdered tetrafluoroethylene resin and graphite fine particles (average particle size 15 μm).
After mixing and molding carbon fiber (average fiber diameter 12.5 μm, average fiber length 0.13 mm),
It is made by firing at a temperature of 380℃, cut to a suitable thickness for a lip seal member, for example, around 0.8 mm, so that the cut surface is smooth, and a circular hole 1' is made in the center as shown in Figure 1. A flat disk-shaped sealing member 1 having a flange portion 12 around the periphery is formed.

(b) Flange portion 12 of the flat disk-shaped seal member 1
is attached to the aforementioned holding ring body 20, and it is attached to the second holding ring body 20.
As shown in the figure, it is attached to the pedestal part 3 of the molding die 2 using a holding jig 4. A molding part 7 having an appropriate curvature is provided on the inner edge of the molding die 2, and comes into contact with the peripheral edge of the circular hole 1' of the flat disc-shaped sealing member 1.

(c) In order to form a lip portion 13 by protruding the inner edge of the circular hole 1' of the flat disk-shaped sealing member 1, the core mold 6 having a tapered end as shown in FIG. 4 from the same direction as the circular hole 1' at the center of the flat disc-shaped sealing member 1 while maintaining a concentric arrangement and pushing out the inner edge. In this case, the diameter m of the tip of the core mold 6 is the same as or slightly smaller than the diameter l of the circular hole 1' of the flat disc-shaped sealing member 1, and the inclined portion 8 of the tip is a lip. The shape and surface condition are such that the portion 13 is not damaged. By inserting the core mold 6 into the center as shown in FIG.
The molding part 7 is formed by the molding part 7 of the molding die 2.
It is formed in the shape of.

(c)' The core mold 6 is appropriately heated to a temperature ranging from room temperature to about 300° C., lower than the temperature at which the sealing base material was fired, and the lip portion 13 is formed in the same manner as in step (c).

(d) When molding is performed through the step (c)', the core mold 6 inserted into the lip portion 13 is air-cooled or water-cooled.

(e) The lip seal 11 with the lip portion 13 formed thereon is taken out from the molding die 2 while attached to the holding ring 20.

To summarize the above methods of forming the lip part 13, in the case of room temperature forming, (a) - (b) - (c) - (e), in the case of heat forming, (a) - (b) - (c)' -(d)-(e) Two manufacturing methods are possible.

Next, the structure of the shaft sealing device such as the holding ring 20 to which the flat disc-shaped sealing member 1 is attached will be described.

As shown in FIG. 4, the flat disc-shaped sealing member 1 is inserted through the O-ring 30 into the holding ring 20 which is tightly fitted with the mounting O-ring 31 on the inner wall of the stepped ring of the compressor container 32. The lip portion 13 is provided in close contact with pressure by a press ring 26 and is molded so that the lip portion 13 that slides and seals against the rotating shaft S of the compressor is on the high pressure side. Then, from the rotating shaft S to the lip seal 11, O
A seal line passing through the ring 30 to the holding ring 20 and a seal line from the holding ring 20 passing through the mounting O-ring 31 to the compressor vessel 32 are formed to seal the fluid.

More specifically, the flat circle is placed in a space surrounded by the cylindrical wall 21 of the holding ring body 20 having an L-shaped cross section and an annular wall 22 extending radially inward from one side edge of the cylindrical wall 21. Flange portion 12 of plate-shaped seal member 1
The pressing ring 26 is provided with a pressing ring wall 27 and a pressing cylinder wall 28 so as to be able to press the ring wall 22 and the O-ring 30 in the direction of the ring wall 22 and the cylinder wall 21. 12 via the O-ring 30, the push ring 26 is pressed and sealed by the axial pressure of the clamping ring 24 formed by crimping the other end of the cylinder wall 21. Further, the clamping portion 29 of the press ring 26 extending radially inward from the press cylinder wall 28 presses and fixes the flange portion 12 to the ring wall 22 at the same time as the above-mentioned sealing. Then, as described above, the peripheral edge of the circular hole 1' of the flat disc-shaped seal member 1 is shaped so as to protrude to one side in the axial direction, so that the flat disc-shaped seal member 1 can be used as a lip seal 11. It is.

Further, the compressor container 32 of the holding ring 20
For sealing mounting from the high pressure side to the compressor container 32, the mounting O-ring 31 is placed in the O-ring groove 33 provided on the inner wall surface of the fixing part of the compressor container 32, and the holding ring body 20 is sealed.
The cylindrical portion 23 is provided by extending the end of the ring wall 22 in the axial direction opposite to the side where the lip seal 11 is tightly fixed, and presses the mounting O-ring 31 in the radial direction. Cylinder wall 21 of ring body 20
A container cylindrical wall 34 and a container annular wall 35 are provided in association with each other on the inner wall surface of the compressor container 32 corresponding to the annular wall 22, and the container cylindrical wall 34 fits into the cylindrical wall 21 of the holding ring 20. The container ring wall 35 is arranged concentrically to prevent the container ring wall 35 from moving in the axial direction due to the pressure of the fluid enclosed in the holding ring 20.

Further, from the side of the clamping ring 24 to the cylinder wall 21,
That is, a cut of an appropriate length is made in the axial direction from the high pressure side, and a part of the cylindrical wall 21 is caulked radially outward to protrude. The cylindrical wall 36 is compressed to ensure installation, and when sealing fluid before use, the retaining ring body 20 is prevented from coming off from the fixed part of the compressor container 32 even if the container sealing part is evacuated. is doing.

〔Effect of the invention〕

According to the shaft sealing device of the present invention constructed as described above, graphite powder and carbon fiber are suitably blended and added to the tetrafluoroethylene resin to form a lip seal. Without sacrificing its excellent qualities,
It can provide mechanical strength and durability that can withstand use even under harsh conditions of high temperature and high pressure such as in an open compressor.

In addition, with the flat disc-shaped seal member attached to the holding ring, the lip part was formed by expanding the peripheral edge of the circular hole with a core mold and protruding to one side in the axial direction, so that it could be attached to the rotating shaft. When the lip is actually operated, the lip has the characteristic of restoring to its original flat disk shape due to the frictional heat on the sliding surfaces and the rise in temperature of the lip due to the ambient fluid, and the restoring force is actively used. By using this method, the rotating shaft can be actively restrained, and the shaft runout can be easily followed even at high temperatures and pressures.
Sealing performance can be improved.

Further, when the lip seal is attached to the holding ring, the flange portion is held between the ring wall of the holding ring and the clamping part of the push ring, so that it can be mechanically and firmly held. O is pressed and held in a fitting recess formed by a pressing ring wall and a pressing cylindrical wall.
It can be elastically compressed by the ring to keep it sealed, and the fixing and sealing functions can be separated and function independently, improving reliability.

Further, since the lip portion 13 is formed while the flat disc-shaped seal member 1 is attached to the holding ring 20, the center of the lip portion 13 can be accurately aligned.

[Brief explanation of drawings]

Fig. 1 is a perspective view of the flat disc-shaped sealing member, Fig. 2 is an abbreviated vertical sectional view showing the state in which the holding ring with the flat disc-shaped sealing member attached is fixed to the molding die, and Fig. 3 is the core. FIG. 4 is a partially omitted vertical cross-sectional view showing the shaft sealing device of the present invention. 1: Flat disc-shaped sealing member, 2: Molding mold, 3:
Pedestal part, 4: Holding jig, 5: Cylindrical holding part, 6:
Core mold, 7: Molded part, 8: Inclined part, 11: Lip seal, 12: Flange part, 13: Lip part, 2
0: Holding ring body, 21: Cylindrical wall, 22: Ring wall, 23:
Cylindrical part, 24: Clamping ring, 25: Cut and raised piece, 26:
Press ring, 27: Press ring wall, 28: Press cylinder wall, 29:
Clamping part, 30: O-ring, 31: O-ring for mounting, 32: Compressor container, 33: O-ring groove, 3
4: Container cylindrical wall, 35: Container ring wall, 36: Stepped cylindrical wall.

Claims (1)

[Claims] 1. Graphite powder added to tetrafluoroethylene resin.
-10% by weight and 3-15% by weight of carbon fiber is added to the lip seal base material to form a flange portion 12 around the periphery and a circular hole 1' in the center.A flat disc-shaped seal member 1, and a cylindrical wall. 21 and an annular wall 22 extending radially inward from one side edge of the cylindrical wall 21, and a mounting O-ring 31 is inserted axially outward from the inner edge of the annular wall 22 into the O-ring groove of the fixing part. A holding ring body 2 is formed by extending a cylindrical portion 23 to press and hold the cylinder wall 21, and a clamping ring 24 extending radially inward from the other side edge of the cylinder wall 21.
0, and a radial clamping part 29 that abuts the flange part 12 that is brought into close contact with the inner surface of the ring wall 22, and is press-fitted between the flange part 12 and the clamping ring 24, and an O-ring 30 is attached to the outer peripheral part. a pressing ring 26 formed by recessing a pressing ring wall 27 and a pressing cylindrical wall 28 to compress and hold the flange portion 12 and the inner surface of the cylindrical wall 21; The lip seal 11 is constructed by press-fitting the core mold 6 into the circular hole 1' of the shaped seal member 1, and pushing the inner edge of the circular hole 1' outward to one side in the axial direction to form the lip part 13. Shaft sealing device.