JPH08145188A - Oil seal - Google Patents

Abstract

PURPOSE: To facilitate the work to secure an oil seal used for sealing high pressure oil to the mate member in a lip side while maintaining pressure tightness due to a back up spring. CONSTITUTION: An oil seal has a lip 8, which is secured between two members 20 and 30, which relatively moves, press-fitted and fixed in the member 20 out of the two members 20 and 30, and contacts facing the member 30 out of the members 20 and 30, the oil, seal is provided with a regular fitting section 12 for securing a back up ring 40 for preventing the lip 8 from deforming to the lip 8 and a second fitting section 16 to which the back up ring 40 is fitted at a position before more than the regular fitting section 12 in the securing direction and nearer the other member 30 to which the lip 8 contacts than the regular fitting section 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil seal provided with a backup ring for sealing high pressure liquid, for example, and more particularly to a structure of a portion to which the backup ring is fitted.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a conventional oil seal of a peripheral seal type. Since the oil seal 102 is an outer peripheral seal, the oil seal 102 is press-fitted into the shaft 120, and its rear end face is brought into contact with the stepped portion 122 of the shaft 120 so as not to be displaced rearward by hydraulic pressure. The lip 108 is inclined forward toward the inner circumference of the hole 132 of the hole 130, and is in contact with the inner circumference of the housing hole 132 with a tight margin. Here, the front side means the sealed fluid side to be sealed, and the rear side means the atmosphere side. Further, 110 is a metal reinforcing ring press-molded into a tubular shape with an outward flange, and is an oil seal 1
No. 02 is inserted from the fixed portion 106 to the rear end face during vulcanization molding of the oil seal 102.

[0003]

However, in the above-described conventional oil seal 102, the housing 130 is mounted from the front (from the direction of arrow A in FIG. 3) after first being press-fitted into the shaft 120. Since the oil seal 102 is used as a seal for high pressure, the lip 1
The high pressure acting on the front surface of 08 may cause the lip 108 to protrude and be damaged, and improvement of pressure resistance is desired.

Generally, in order to improve the pressure resistance of the lip 108, the method of increasing the volume of the lip 108 is inexpensive as shown by the broken line 109, but on the other hand, the rigidity of the lip 108 increases due to the increase of the volume, so that the housing 1
When the 30 is attached, the insertion resistance of the lip 108 increases, which makes it impossible to attach the lip 108, or there is a concern that the lip 108 may be reversed to the atmosphere side.

On the other hand, in order to reduce the insertion resistance increased due to the volume increase of the lip 108, the lip 10
Although there is also a method of reducing the tightening margin of No. 8, there is a disadvantage that the followability of the lip 108 with respect to shake during rotation is deteriorated.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and its purpose is to:
It is an object of the present invention to provide an oil seal that can be easily mounted on a lip side mating member while maintaining the pressure resistance of the backup ring for the high pressure oil seal.

[0007]

In order to achieve the above object, according to the present invention, it is mounted between two members which move relative to each other, and is press-fitted and fixed on one of the two members.
In an oil seal having a lip that contacts the other member of the two members from the fixed portion, a regular fitting portion for mounting a backup ring on the lip to prevent deformation of the lip, and the regular fitting portion. The second backup ring is fitted at a position in front of the fitting portion in the mounting direction, at a position in front of the root of the lip in the mounting direction, and on the side of the other member with which the lip contacts the regular fitting portion. It is characterized in that a fitting portion is provided.

It is preferable that a protrusion is provided on the peripheral surface of the backup ring on which the backup ring is fitted, and the second fitting portion is shaped so as to engage with the protrusion of the backup ring.

[0009]

In the oil seal having the above structure, when the oil seal having the backup ring is mounted between the two members, the backup ring is expanded or contracted so that the lip comes into contact with the regular fitting portion. When fitted into the second mating portion located on the side, the backup ring tries to return to its original diameter due to its own elastic force, thus exerting a force on the lip. Since the position of the second fitting portion is located in front of the base of the lip in the mounting direction, the force that tries to reduce (expand) or expand (when shrink) the backup ring is a bending moment, and the tip of the lip is also lip. The tip is moved away from the contacting member, that is, the lip interference is reduced. As a result, the mounting resistance of the oil seal (lip insertion resistance) is reduced, and mounting becomes easy.

On the other hand, since the backup ring is on the member side where the lip contacts in the front in the mounting direction, for example, in the case of an outer peripheral seal, when the oil seal is inserted, the backup ring comes into contact with the end surface of the housing and is further inserted, so Is disengaged from the second fitting portion and is fitted to the regular fitting portion on the lip side behind the second fitting portion in the mounting direction. As a result, the pressure resistance of the oil seal by the backup ring is maintained.

Then, the second fitting portion is provided with a protrusion on the circumferential surface on the side where the backup ring is fitted, and the second fitting portion is shaped to engage with the projection of the backup ring. Since the backup ring that is fitted to is only the protrusion, when the oil seal is attached, the backup ring will easily come off the second fitting part and be fitted to the regular fitting part. , The mounting work becomes easier.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. An example in which an oil seal according to an embodiment of the present invention is applied to a peripheral seal type oil seal will be described with reference to FIGS. 1 and 2.

Since the oil seal 2 is an outer peripheral seal, it is press-fitted into the shaft 20 and the rear end face 4 is fixed to the shaft 20 so that the oil seal 2 does not shift to the atmosphere side (hereinafter referred to as rear), that is, rearward.
The fixed portion 6 on the shaft 20 side is applied to the stepped portion 22 of the
To the inner circumference of the hole 32 of the housing 30 from the lip 8
Is inclined toward the sealed fluid side (hereinafter referred to as the front), that is, extends forward, and is in contact with the inner periphery of the housing hole 32 with a tight margin. Further, 10 is a metal-made reinforcing ring press-molded in a tubular shape with an outward flange, and the oil seal 2 is provided at a position from the fixed portion 6 of the oil seal 2 to the rear end face 4.
It was inserted during vulcanization molding.

A fitting groove 12 into which the backup ring 40 is fitted is provided behind the lip 8 in the oil seal 2, and the fitting groove 12 serves as a regular fitting portion when it functions as an oil seal. .

The backup ring 40 is a ring having a substantially rectangular cross section, but a ring-shaped protrusion 42 having a low semicircular cross section on the front side of the inner peripheral surface 41 (the front side in the mounting direction described later). Is provided. The regular fitting groove 12 of the oil seal 2 has a shape that can be fitted to the inner peripheral surface 41 of the backup ring 40 including the protrusion 42. The front surface of the backup ring 40 contacts the front wall 14 (the surface behind the lip 8) generated by the fitting groove 12, and the rear end surface of the backup ring 40 is the same as the rear end surface 4 of the oil seal 2 and the shaft 20. It contacts the stepped portion 22 of. The backup ring 40 is molded of resin to have pressure resistance, and is further cut (see FIG. 2 to facilitate expansion and contraction of the diameter of the backup ring 40).
V cut shown in (a) and (b), or FIG.
The U-cut shown in (d) and (e) is inserted.

Further, the oil seal 2 is located in front of the regular fitting groove 12 and further in front of the root of the lip 8 (forward in the mounting direction described later) and in the housing hole more than the regular fitting groove 12. A second fitting groove 16 having a diameter larger than that of the regular fitting groove 12 is provided on the 32 side, and the second fitting groove 16 is a ring-shaped protrusion of the inner peripheral surface 41 of the backup ring 40. It is adapted to fit with 42.

Then, as shown in FIG. 1B, the backup ring 40 is expanded and the backup ring 4 is expanded.
When the zero protrusion 42 is fitted into the second fitting groove 16 of the oil seal 2, the backup ring 40 tries to return to its original diameter by its own elastic force, and therefore exerts a force on the lip 8. Since the position of the second fitting groove 16 is located in front of the base of the lip 8 in the mounting direction, the force for reducing the backup ring 40 becomes a bending moment, and the lip 8
Also, the tip of is moved inward from the dotted line to the solid line, that is, the tightening margin of the lip 8 is reduced from a to b.

When assembling the oil seal 2, the oil seal 2 is first attached to the shaft 20 with the backup ring 40 fitted in the second fitting groove 16 of the oil seal 2 via the projection 42. After press fitting, as shown in FIG. 1B, the housing 30 is mounted from the front (from the arrow A direction in the figure). In this case, the tightening margin of the lip 8 is reduced as described above, and the mounting resistance to the housing 30 is small, so that the mounting is easy. Then, as the mounting of the housing 30 progresses, the end chamfered portion 34 of the housing hole 32 hits the front end of the backup ring 40 and tries to push it out. The ring-shaped protrusion 4 of the backup ring 40
Since 2 has a low height and a semicircular cross section, the fitting / engagement of the backup ring 40 and the second fitting groove 16 of the oil seal 2 is easily disengaged, and the backup ring 40 is shown in FIG.
(B) The position indicated by the solid line is changed to the original position indicated by the dotted line, that is, the fitting groove 12 is fitted. As a result, the following functions are maintained.

The function of the backup ring 40 fitted in the regular fitting groove 12 is on the rear side of the lip 8.
By supporting the lip 8 that receives a high pressure from the front hydraulic pressure and is largely deformed rearward together with the stepped portion 22 of the shaft 20 on the rear side of the backup ring 40 from the rear side, the pressure resistance of the lip 8 is increased. is there.

In this embodiment, the lip 8 has the housing hole 3
Although the so-called outer peripheral seal type oil seal contacting the inner peripheral surface of 2 has been described, the present invention is also applicable to a so-called inner peripheral seal type oil seal in which the lip 8 contacts the outer peripheral surface of the shaft 20.

In this case, the backup ring is also on the inner peripheral side, and the second fitting groove is on the axial side of the regular fitting groove, that is, at a position having a smaller diameter than the regular fitting groove.

When the backup ring is contracted and fitted into the second fitting portion, the backup ring tries to return to its original diameter due to its own elastic force, and thus exerts a force on the lip. At this time, the force to expand the backup ring becomes a bending moment, and the tip of the lip is also moved outward, that is, the tightening margin with the shaft of the lip is reduced, and the mounting work is facilitated.

Further, in this embodiment, the projection 42 is provided on the inner peripheral surface 41 of the backup ring 40, and the second fitting groove 16 is provided.
The shape of the backup ring has been described as an example along the shape of the protrusion 42. However, although the backup ring may be less likely to come off the second fitting portion, the backup ring does not have the protrusion 42. Is also good.

Further, in this embodiment, the backup ring 40 is described as being molded of resin. This is because it is desirable in order to have the pressure resistance of the backup ring, but other materials may be used as long as this condition is satisfied.

Further, although the case where the reinforcing ring 10 is provided has been described as an example, the reinforcing ring 10 may not be provided depending on the material of the oil seal or the usage condition.

Further, if only the original function of the backup ring is considered, no cut may be made, but in the case of the present invention, expansion / contraction of the diameter of the backup ring for fitting to the second fitting portion is facilitated. In order to
V as shown in (a) and (b) and FIGS. 2 (c), (d),
It is preferable to insert a U-shaped cut 43 or the like as shown in (e).

Further, in order to exert the function of the backup ring, it is necessary to support the backup ring from the rear side, which has been described with the stepped portion 22 of the shaft 20 in the above-mentioned embodiment, but other embodiments. Alternatively, as shown in FIG. 2 (f), a ring stopper type in which the backup ring 40 is supported from behind by the reinforcing ring 50 may be used.

[0028]

As described above, according to the present invention,
When the oil seal equipped with the backup ring was mounted between the two members, the backup ring was expanded or contracted to fit the second fitting portion located on the member side where the lip contacts the regular fitting portion. In this case, the backup ring tries to return to its original diameter due to its own elastic force,
Power will be applied to the lip. Since the position of the second fitting portion is in the mounting direction forward of the base of the lip,
The force that tries to reduce (expand) or expand (when contracting) the backup ring is a bending moment that moves the lip tip away from the member with which it contacts, that is, the lip tightening margin is reduced. Become. As a result, the mounting resistance (lip insertion resistance) of the oil seal is reduced, and the mounting can be facilitated.

On the other hand, since the backup ring is on the member side with which the lip contacts in the front in the mounting direction,
For example, in the case of an outer peripheral seal, when the oil seal is inserted, the backup ring comes off the second fitting portion by hitting the end surface of the housing and further inserting, and the backup ring is behind the second fitting portion in the mounting direction and on the lip side. It will be attached to the regular fitting part. Thereby, the pressure resistance of the oil seal by the backup ring can be maintained.

Then, a protrusion is provided on the peripheral surface on the side where the backup ring is fitted, and the second fitting portion is shaped so as to engage with the projection of the backup ring. Since the backup ring that is fitted to is only the protrusion, when the oil seal is attached, the backup ring will easily come off the second fitting part and be fitted to the regular fitting part. , The mounting work becomes easier.

[Brief description of drawings]

FIG. 1 (a) is a cross-sectional view of an oil seal according to an embodiment of the present invention after being mounted between two members, and FIG. 1 (b) is a cross-sectional view during mounting.

2 (a) to 2 (e) show cuts of a backup ring used in an oil seal according to an embodiment of the present invention. FIG. 11A is a front view of a V-cut main portion, and FIG. 9B is a bottom view of the main portion of FIG. Further, FIG. 7C is a front view of a main part of the U-shaped cut, and FIGS. 7D and 7E are bottom views of the main part showing the cutting mode of FIG. FIG. 6 (f) is an oil seal according to another embodiment of the present invention, which is a cross-sectional view of the main part of a ring-stop type backup ring.

FIG. 3 is a cross-sectional view of a conventional oil seal.

[Explanation of symbols]

 2 Oil seal 4 Rear end face 6 Fixing part 8 Lips 10, 50 Reinforcing ring 12 Regular fitting groove (regular fitting part) 14 Wall 16 Second fitting groove (second fitting part) 20 Shaft 22 steps Attached part 30 Housing 32 Housing hole 34 Chamfering part 40 Backup ring 41 Inner peripheral surface 42 Projection part 43 Cut

Claims (2)

[Claims] 1. Oil having a lip that is mounted between two members that move relative to each other, is press-fitted and fixed on one member side of the two members, and is in contact with the other member of the two members from the fixing portion. In the seal, a regular fitting portion for mounting a backup ring on the lip to prevent deformation of the lip, and a position in front of the regular fitting portion in the mounting direction and in a position in front of the root of the lip in the mounting direction. An oil seal characterized in that a second fitting portion, into which the backup ring is fitted, is provided on the side of the other member that is in contact with the lip with respect to the regular fitting portion. 2. The backup ring is provided with a projection on the peripheral surface on the side where the backup ring is fitted, and the second fitting portion is shaped to engage with the projection of the backup ring. Oil seal as described.