JP6617523B2 - Sealing device and method of manufacturing sealing device - Google Patents

Description

  The present invention relates to a sealing device such as an oil seal and a method for manufacturing the sealing device.

Many oil seals are used in automobile applications, including oil seals for transmissions and differential gears.
Oil seals for these applications are required to have a low torque in response to demands for low fuel consumption as well as oil sealability.
As a technique for reducing the torque of the oil seal, a technique of forming irregularities on the sliding surface of the oil seal (seal lip) has been proposed.

  For example, Patent Document 1 describes that a small unevenness is formed on a part or all of a sliding surface of a seal lip by transferring a mold to reduce torque.

JP 2008-8455 A

As proposed in Patent Document 1, it is possible to reduce the torque by providing irregularities on the sliding surface of the seal lip.
On the other hand, when unevenness is provided on the sliding surface of the seal lip by transferring a mold, the convex portion usually has a sharp mountain shape. The slidable contact surface of the seal lip having the convex portion having such a shape is likely to be worn when slidably contacting the mating member, and as a result, the unevenness (convex portion) of the slidable contact surface may disappear. . Therefore, a seal lip (oil seal) having a sliding contact surface formed by transferring a mold has a problem that a low torque cannot be maintained over a long period of time.
On the other hand, it is conceivable to make the convex portion high in order to maintain a low torque over a long period of time. There is a problem that it cannot be done.
Thus, the reduction in torque and the excellent oil sealability are in a trade-off relationship, and it has been difficult to achieve both.

  The present invention has been made in view of the above-described problems, and a sealing device capable of reducing the torque of the seal lip while ensuring excellent oil sealing performance, and the manufacture of such a sealing device. Aims to provide a method.

  The sealing device of the present invention has an annular seal lip having a sliding contact surface that slidably contacts a sealing surface of a mating member, and seals fluid by contact between the sealing surface and the sliding contact surface The apparatus is characterized in that the seal lip contains a detachable powder, and the detachable powder is unevenly distributed on the sliding surface side of the seal lip.

  In such a sealing device, since the seal lip contains detachable powder in the vicinity of the slidable contact surface, when the slidable contact surface of the seal lip slides with the seal surface of the mating member, the seal lip is worn. Along with this, the detachable powder gradually falls off the seal lip. When the detachable powder falls off, the slidable contact surface becomes a concave portion in the portion where the detachable powder was present, and the other portion becomes a smooth surface. In the sealing device, since the concave portion is formed by dropping off the detachable powder, the sliding contact area is reduced, and the oil can be held in the formed concave portion, so that the torque of the seal lip is reduced. Is achieved. Moreover, since the part other than the recessed part of the said sliding contact surface is a smooth surface, the outstanding oil-sealing property is also ensured.

In the sealing device, the seal lip is made of a rubber composition containing a rubber component and a detachable powder, and the detachable powder is at least one of silicone powder, polyethylene powder, and fluororesin powder. It is preferable.
When the detachable powder is at least one of silicone powder, ethylene resin powder, and fluororesin powder, these detachable powders have poor adhesion to rubber, so that the seal lip slides on the mating member. It can be easily removed when moved, and the recess can be reliably formed by the sliding surface of the seal lip.

In the sealing device, it is preferable that an average particle diameter of the detachable powder is smaller than a sliding contact width on the sliding contact surface of the seal lip.
Thereby, when a recessed part is formed in the sliding contact surface of the said seal lip, it can avoid that oil leaks and can ensure the sealing property of oil more reliably.

  In the sealing device, the average particle diameter of the removable powder is preferably 5 to 40 μm. By using the detachable powder having an average particle diameter in this range, it is possible to provide a recess suitable for achieving both low torque and oil sealability on the sliding surface of the seal lip.

The manufacturing method of the sealing device of the present invention has an annular seal lip provided with a sliding contact surface slidably contacting a sealing surface of a mating member, and fluid is supplied by contact between the sealing surface and the sliding contact surface. A method of manufacturing a sealing device for sealing,
At least the following steps (1) and (2) are performed.
(1) The process of apply | coating the mold release agent solution containing a detachable powder to the area | region which forms the said sliding contact surface of a metal mold | die inner surface.
(2) A step of casting the raw material composition into the mold and vulcanization molding.
Such a sealing device manufacturing method is suitable for manufacturing the sealing device of the present invention having a seal lip in which the detachable powder is unevenly distributed on the sliding contact surface side because the steps (1) and (2) are performed. ing.

According to the sealing device of the present invention, it is possible to reduce the torque of the seal lip while ensuring excellent oil sealability. In addition, by reducing the torque of the seal lip, in the sealing device, heat generation of the seal lip during sliding can be suppressed, and sag due to thermal aging of the seal lip can be suppressed.
According to the manufacturing method of the sealing device of the present invention, the sealing device of the present invention can be preferably manufactured.

It is a section perspective view of the oil seal concerning a 1st embodiment of the present invention. It is a principal part expanded sectional view of FIG. It is a schematic diagram which shows typically the sliding contact surface of the oil seal shown in FIG. 1, and its vicinity. It is a principal part expanded sectional view of the oil seal concerning 2nd Embodiment of this invention. (A), (b) is a schematic diagram for demonstrating the manufacturing method of the sealing device concerning embodiment of this invention. In the oil seal produced by the Example and the comparative example, it is a laser microscope observation image of the air inclined surface of a seal lip, (a) is an observation image of Example 1, (b) is an observation image of Comparative Example 1. is there. It is a graph which shows the relationship between the contact reaction force and the torque in the oil seal produced by the Example and the comparative example.

Hereinafter, a sealing device according to an embodiment of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 is a cross-sectional view of an oil seal according to a first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a main part of FIG. FIG. 3 is a schematic view schematically showing the sliding contact surface of the oil seal shown in FIG. 1 and the vicinity thereof.
The oil seal 10 is formed in an annular shape, and an outer peripheral portion thereof is fixed to, for example, a transmission housing 35 and the like. Seal. The oil seal 10 is formed by vulcanizing and bonding a metal core member 11 and an elastic member 12. The metal core member 11 has an L-shaped cross section by a portion 14 parallel to the axial direction and a vertical portion 15. It is formed by bending. The elastic member 12 is bonded so as to cover the outer peripheral surface of the parallel portion 14 and the one axial side surface of the vertical portion 15 of the metal core member 11, and includes a seal lip 18 and a dust lip 19 on the radially inner side. A tightening spring 13 for assisting a tightening force is provided on the outer peripheral surface of the seal lip 18.

The dust lip 19 extends toward the rotary shaft 36 and prevents dust from passing between the dust strip 19 and the rotary shaft 36. Further, the dust lip 19 extends obliquely in a direction away from the seal lip 18.
The seal lip 18 is disposed on the inner peripheral side of the parallel portion 14 of the core member 11 and has a concave groove 18a for fitting the tightening spring 13 on the outer peripheral surface thereof, and the inner peripheral surface is radially inward. It has a tapered shape toward. Therefore, on the inner peripheral surface of the seal lip 18, two inclined surfaces 20 and 23 are formed on both sides in the axial direction with the tapered tip edge (boundary edge) 24 as a boundary, and are inclined in opposite directions.

  One inclined surface 20 arranged away from the dust lip 19 is an oil side (fluid side) inclined surface arranged on the oil holding side, and the other inclined surface 23 arranged on the dust lip 19 side is the atmospheric air. It is a side (air side) inclined surface. In the seal lip 18, a part of the atmosphere-side inclined surface 23 is a portion mainly constituting a sliding contact surface that is in sliding contact with the outer peripheral surface (seal surface) 36 a of the rotating shaft 36. The seal lip 18 is curved radially outward by contacting the outer peripheral surface 36a of the rotary shaft 36, and contacts the outer peripheral surface 36a in a wide range of the sliding contact surface (atmosphere side inclined surface) 23. The seal lip 18 is shown in an uncurved state.

The seal lip 18 contains a detachable powder 30 and is made of a composition containing an elastic material and a detachable powder. Here, as shown schematically in FIG. 2, the detachable powder 30 is unevenly distributed on the atmosphere-side inclined surface 23 side (sliding contact surface side) in the seal lip 18.
In the oil seal 10 having such a seal lip 18, when the seal lip 18 is in sliding contact with the rotary shaft 36, the detachable powder 30 is dropped from the sliding contact surface as the sliding contact surface is worn. As a result, a recess is formed on the sliding contact surface.

  Further, since the concave portion is formed on the sliding contact surface of the seal lip 18 by the removal of the detachable powder 30, as shown in FIG. 3, the sliding contact surface 33 has a smooth surface 32 and a substantially hemispherical concave portion 31. It will be composed of. In such a slidable contact surface 33, oil can be held by the substantially hemispherical concave portion 31, and this point can also contribute to lowering the torque of the oil seal.

  As the elastic material, for example, synthetic rubber such as nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), acrylic rubber (ACM), fluoro rubber (FKM), natural rubber, elastic resin, or the like is used. it can.

  As the detachable powder, a powder having poor adhesion to the main component (rubber component) constituting the seal lip can be used. For the synthetic rubber and natural rubber, for example, silicone powder, polyethylene powder, fluororesin powder and the like can be preferably used.

Other examples of the detachable powder include powders made of polyolefins other than polyethylene such as polypropylene powder, other resin powders such as acrylic resin powder, inorganic powders, metal powders, etc., which are main components (rubber) Some components can be used.
The detachable powder may be a resin whose surface is coated with a silicone resin, a fluorine resin, or the like.
As for the said detachable powder, only 1 type may be used and 2 or more types may be used together.

Specific examples of the silicone powder include Tospearl series (for example, Tospearl 2000B, Tospearl 1100, Tospearl 1110, etc.) manufactured by Momentive. Since this silicone powder has a methyl group on its surface and has poor adhesion to synthetic rubber or the like, it can be easily removed from the sliding surface of the seal lip. Moreover, since this silicone powder has a narrow particle size distribution, it is suitable for forming concave portions having a uniform shape.
As said fluororesin powder, the powder etc. which consist of PTFE are mentioned, for example. Since the powder made of PTFE has a perfluoroalkyl group on its surface, it has poor adhesion to synthetic rubber and the like, and can easily fall off from the sliding surface of the seal lip.

The average particle diameter of the detachable powder is preferably smaller than the sliding contact width W (see FIG. 3) on the sliding contact surface 33 of the seal lip. Here, the sliding contact width W refers to the length in the axial direction at the sliding contact portion of the seal lip with the mating member.
When the average particle diameter of the detachable powder is equal to or larger than the sliding contact width, a recess may be formed across the sliding contact surface in the width direction due to dropping of the detachable powder. Oil sealability may be reduced.
In the present invention, the average particle diameter of the detachable powder may be measured by a particle size analyzer of the pore electrical resistance method using the Coulter principle.

The average particle diameter of the detachable powder 30 is preferably 5 to 40 μm from the viewpoint of achieving both low torque and oil sealing properties.
If the average particle diameter is less than 5 μm, it may not be possible to sufficiently reduce the torque. On the other hand, if the average particle diameter exceeds 40 μm, the recesses formed by dropping off the detachable powder are large. As a result, oil leaks along the recess, and the sealing performance of the oil may deteriorate.

Further, the detachable powder 30 is preferable as the particle size distribution is narrow and the particle diameter is uniform.
In this case, the recess formed by the detachment of the detachable powder becomes a recess having a uniform shape.

[Other Embodiments]
FIG. 4 is an enlarged cross-sectional view of a main part of an oil seal according to the second embodiment of the present invention.
In the second embodiment, as schematically shown in FIG. 4, the detachable powder 30 may be unevenly distributed on both sides of the atmosphere-side inclined surface 23 and the oil-side inclined surface 20 in the seal lip 18.
When the seal lip 18 is in sliding contact with a mating member such as a rotating shaft, part of the oil-side inclined surface 20 may also be in sliding contact with the mating member. In this case, since the detachable powder 30 is also unevenly distributed on the oil side inclined surface 20 side, it is possible to achieve lower torque more reliably.

In the oil seal according to the embodiment of the present invention, the detachable powder is unevenly distributed on the sliding contact surface side of the seal lip. Here, being unevenly distributed on the slidable contact surface side means being unevenly distributed on the mating member side of the seal lip, and the detachable powder may be present only on the slidable contact surface and its vicinity. Alternatively, it may be present on the entire mating member side of the seal lip.
Further, the oil seal according to the embodiment of the present invention may contain a detachable powder in a portion other than the sliding contact surface side of the seal lip.

The sealing device according to the embodiment of the present invention can be manufactured, for example, by the method for manufacturing the sealing device according to the embodiment of the present invention.
Hereinafter, the manufacturing method of the sealing device according to the embodiment of the present invention will be described in the order of steps.
5A and 5B are schematic views for explaining a method for manufacturing a sealing device according to an embodiment of the present invention.

(1) A release agent solution 53 containing a detachable powder is applied to the inner surface of the mold 50 by a spray 54 or the like.
At this time, the release agent solution may be applied only to the inner surface 51A of the female mold 51 (first method: see FIG. 5A), or the inner surface 52A of the male mold 52 and the inner surface 51A of the female mold 51. It may be applied to both of them (second method).
In the case of the first method, in the molded seal lip, as shown in FIG. 2, the detachable powder is unevenly distributed on the atmosphere-side inclined surface 23 of the seal lip 18.
On the other hand, in the case of the second method, in the molded seal lip, as shown in FIG. 4, the detachable powder is unevenly distributed on both sides of the air-side inclined surface 23 and the oil-side inclined surface 20 of the seal lip 18. ing.

As the release agent solution, for example, a conventionally known silicone release agent or fluorine release agent in which the releasing powder is dispersed can be used.
In the release agent solution, the concentration of the detachable powder is not particularly limited, and may be, for example, 2 to 50 g / l.
Moreover, what is necessary is just to apply | coat the said mold release agent solution, for example so that the application quantity per unit area of a mold inner surface may become 400-20000 g / m < ² >.

(2) Next, the raw material composition is cast into the mold 50 and vulcanized and molded under predetermined conditions.
As the raw material composition, for example, an unvulcanized rubber and a vulcanizing agent, and a composition containing various additives such as a vulcanization accelerator, if necessary, may be used. In advance, each compounding component is weighed and mixed.

  Further, in this step, when the raw material composition is vulcanized, the cored bar member 11 may be provided in advance in the mold, and the cored bar member 11 and the elastic member 12 may be vulcanized and bonded. Thereby, a manufacturing man-hour can be reduced.

(3) Thereafter, the molded product is taken out from the mold, and if necessary, the clamping spring 13 is fitted to obtain an oil seal.
By passing through such a process, the oil seal 10 in which the detachable powder 30 is unevenly distributed on the sliding surface side of the seal lip 18 can be manufactured.
In addition, according to the manufacturing method according to the present embodiment, since the periphery of the detachable powder is contained in the seal lip in a state of being covered with the release agent, the detachable powder has a seal lip. It is excellent in detachability when it comes into sliding contact with the mating member.

EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, embodiment of this invention is not limited to a following example.
Here, an oil seal (Example 1) in which the detachable powder is unevenly distributed on the sliding surface side of the seal lip as shown in FIGS. 1 and 2 and an oil seal in which the seal lip does not contain the detachable powder (comparison) Example 1) was fabricated and the low torque effect was verified.

(Example 1)
A rubber component (NBR) and a vulcanizing agent (sulfur) prepared separately were applied to the inner surface of the mold (51A in FIG. 5) after applying a release agent solution in which a releasing powder was dispersed. The raw material composition contained therein was cast, and a cored bar member was further installed to form a vulcanization to produce an oil seal.
Here, as the release agent solution, a solution in which silicone powder (Mostivive, Tospearl 1100) was dispersed in a fluorine-based release agent (concentration: 30 g / l) was used.
Moreover, the coating amount per unit area of the mold inner surface of the release agent solution was 2500 g / m ² .

(Comparative Example 1)
An oil seal was produced in the same manner as in Example 1 except that a fluorine-based mold release agent containing no detachable powder was used as the mold release agent solution.

About the oil seal produced in each of an example and a comparative example, the sliding contact surface (atmosphere side inclined surface) of a seal lip was observed with the laser microscope.
As a result, as shown in FIG. 6 (a), in the oil seal of Example 1, the detachable powder is sufficiently distributed on the sliding contact surface, whereas as shown in FIG. 6 (b). In the oil seal of Comparative Example 1, the sliding contact surface was smooth.
Further, the surface roughness Rz (conforming to JIS B 0601: 2001) of each sliding contact surface was 15 μm in Example 1 and 3 μm in Comparative Example 1.

Next, for the oil seals of Example 1 and Comparative Example 1, the relationship between the contact reaction force (N / mm) and the torque (mN · m) was measured with a seal torque tester (manufactured in-house). The results are shown in FIG.
As a result, the oil seal in Example 1 was found to have a torque reduction effect of about 24% compared to the oil seal in Comparative Example 1.

10: oil seal, 11: cored bar member, 12: elastic member, 13: clamping spring,
18: Seal lip, 19: Dustrip, 20: Oil side inclined surface, 23: Atmospheric side inclined surface,
30: detachable powder, 31: recess, 32: smooth surface, 35: housing, 36: rotating shaft,
50: mold, 51: female mold, 52: male mold, 53: release agent solution

Claims (1)

A manufacturing method of a sealing device having an annular seal lip having a sliding contact surface slidably contacting a sealing surface of a mating member and sealing a fluid by contact between the sealing surface and the sliding contact surface. ,
The manufacturing method of the sealing device characterized by passing through the process of following (1) and (2) at least.
(1) The process of apply | coating the mold release agent solution containing a detachable powder to the area | region which forms the said sliding contact surface of a metal mold | die inner surface.
(2) A step of casting the raw material composition into the mold and vulcanization molding.