JPS6212933Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sealing device for sealing between two concentrically assembled members. More specifically, when the two members rotate relative to each other, negative pressure is generated in the annular space between the dust lip and the main lip, and the contact surface pressure for drawing the main lip and the dust lip toward each other for sealing becomes excessive. This invention relates to an improved sealing device.

Prior art related to the present invention is shown in FIG. 1. FIG. 1 shows a half cross section of an oil seal 3, in which a base portion 5 is integrally fixed to a support portion 9 extending radially inward from an outer peripheral portion 1 fixed to the housing, and a shaft 6 is attached to the base portion 5. A dust lip 2 and a main lip 4 made of a rubber-like elastic material are formed to be bifurcated in a diagonal direction. There is an annular space 7 between the dust lip 2 and the main lip 4,
When the distal end seals of the dust lip 2 and the main lip 4 are in sealing contact with the shaft 6, the annular space 7 forms an annular cavity. In this configuration, when the shaft 6 rotates, the fluid in the annular cavity is sucked into the inner side of the main lip 4 (towards the right in the figure) due to the sealing action of the main lip 4. However, since the dust strip 2 is in sealed contact with the shaft 6, no fluid flows into the annular cavity, so that the pressure in the annular cavity becomes increasingly negative. Then, since the dust lip 2 and the main lip 4 are made of rubber, they are deformed so as to be drawn into the annular cavity under negative pressure. At this time, both lips 2 and 4 are pressed against the circumferential surface of the shaft 6, so friction increases, and this frictional portion causes heat generation and abnormal wear. Therefore, a problem arises in the sealability of the lip as a sealing device.

Also, in order to prevent negative pressure in the annular cavity, a second
As shown in the figure, there is a dust lip 12 with a hole 9, but in this configuration, the hole 9 is always open, so dust enters the annular cavity and the sealing surfaces of both lips. In particular, it has the disadvantage that it adheres to the sealing surface of the main lip 4 and prematurely wears out the sliding surface.

The present invention was developed in view of the above-mentioned problems, and its purpose is to create a negative pressure in the annular cavity between the dust lip and the main lip so that the sealing surfaces of both lips are pressed against the sliding surface. The objective is to effectively prevent the deterioration of sealing performance due to wear and tear.

Therefore, the present invention is constructed as follows. That is, it seals the gap between the hole and the shaft that are combined concentrically with each other, and includes a fixed part fixed to the circumferential surface of one of the two members, and a fixed part integrally connected to the fixed part. It has a base, a dust lip extending from the base and inclined with respect to the axis, and a main lip extending from the base and forming an annular space between the dust lip and the dust lip, the dust lip being on the end circumferential side and forming the other member. A seal part that contacts the circumferential surface, and a groove or a protrusion disposed on the circumferential surface on the side of the annular space and formed from near the seal part toward the protruding base side, and the groove part side circumferential surface or protrusion Upon contact with the circumferential surface of the other member, a passage is formed between the circumferential surface of the other member and the groove or protrusion side to communicate the annular space with the atmosphere.

The present invention, with the above-described configuration, produces the following unique effects.

That is, when the peripheral surface of the other member comes into contact with the sealing portion between the dust lip and the main lip, the annular space forms an annular cavity. Since the main lip is configured to seal the side opposite to the annular cavity in the axial direction, when the main lip and the other member rotate relative to each other, the main lip prevents fluid from leaking toward the annular cavity. In order to prevent this, the fluid in the annular cavity is sucked into the other side in the axial direction. As a result, the pressure in the annular cavity becomes negative, so that the dust strip deforms in an arched manner toward the annular cavity, and the circumferential surface of the dust strip on the annular cavity side comes into contact with the circumferential surface of the other member. At this time, a passage is formed between the side surface of the groove or the protrusion and the circumferential surface of the other member to communicate the atmosphere side with the annular cavity.
Negative pressure in the annular chamber is eliminated. Therefore, the dust lip and main lip seals provide an effective seal. Further, since the communication between the atmosphere and the annular cavity is for a short time, there is an effect of minimizing the intrusion of dust from the atmosphere side into the annular cavity.

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings. FIG. 3 shows a half cross section of the sealing device of the present invention. A layer of rubber-like elastic material is integrated with the outer periphery of the reinforcing ring 11 to form a fixed part 18, and a base part 15 that is integrally fixed to a support part 19 at one end of this fixed part 18 is inclined with respect to the shaft 16. The annular dust strip 12 is provided with a seal 20 on its inner diameter for contacting the shaft 6. Further, the annular main lip 14 extending from the base 15 to form an annular space 17 with the dust lip 12 is provided with a seal portion 21 on the inner diameter side where it contacts the shaft 16. This seal part 21
is pressed radially inward by an annular spring 22 from the outer circumferential side. A plurality of convex portions 24 extending from the vicinity of the seal portion 20 toward the base portion 15 are integrally provided on the peripheral side surface 23 of the dust strip 12 on the annular space side. Incidentally, it is preferable that the convex portion 24 be formed so as to be inclined with respect to the axial direction so that the fluid can be easily sucked in when the shaft 16 rotates.

Fixed part 1 of the oil seal configured in this way
8 into the hole in the housing, and then attach the dust strip 12.
When shaft 16 is inserted into the inner diameter of main lip 14, sealing portion 20 of dust lip 12 and sealing portion 21 of main lip 14 are in sealing contact with shaft 16, so that annular space 17 forms an annular cavity. Then, due to the shaft sealing function of the main lip 14, the fluid in the annular cavity is sucked into the other side through the seal portion 21, so that a negative pressure is created in the annular cavity. As a result, the dust 12 is deformed into an arch toward the annular cavity, and the tip side of the circumferential surface 23 on the annular cavity side comes into contact with the shaft 16. However, since a plurality of convex portions 24 are provided on the circumferential side surface 23 in contact with the shaft 16, the circumferential surface of the shaft 16, the convex portions 24, and the convex portions 24
A passage 30 as shown in FIG. 4 and FIG. At the same time, since the seal portion 20 is separated from the shaft 16, the atmosphere side and the annular cavity communicate with each other, and the negative pressure within the annular cavity is eliminated. Therefore, it is expected that the sealing performance and sliding resistance of the dust lip 12 and the main lip 14 with respect to the shaft 16 will be improved, and that wear and the like of both the seal portions 20 and 21 will be prevented. In addition, the main lip 14 acts to suck the fluid in the annular cavity towards the sealing side in order to maintain the sealing function, but since this suction action is performed gradually, the annular space forming the annular cavity By increasing the volume, wear of the seal portion 20 of the dust strip 12 due to negative pressure can also be reduced.

Figure 6 shows the dust strip 1 of another embodiment of the present invention.
2 is a sectional view of FIG. A groove portion 25 is formed on the circumferential side of the dust strip 12 on the side of the annular space in the vicinity of the seal portion 20 and is inclined with respect to the axial direction.

In this case, the pressure inside the annular cavity becomes negative and the dust strip 12 deforms into an arcuate shape toward the annular cavity, and the sealing part 2
When the 0 side circumferential surface 23 comes into contact with the shaft 16, the circumferential surface 2
3 has a plurality of grooves 25 arranged therein, so that the contact surface side is deformed into an arched shape, and the seal part 20 becomes separated from the shaft 16, and the grooves 25 communicate the atmosphere side and the annular cavity. I will let you do it. The groove portion 25 is inclined with respect to the axis, and this inclination is formed so that when the shaft 16 rotates, it is easy to suck in fluid from the atmosphere side, so that the negative pressure in the annular cavity is effectively reduced. can be resolved.
FIG. 7 shows an embodiment in which a large number of grooves 25 are provided on the peripheral side surface 23 of the dust strip 12. In this case, the cross-sectional area of the groove is made small to prevent dust from entering together with the fluid when the fluid flows into the annular cavity. Moreover, the groove portion 25 is
3, it is formed so as to be inclined with respect to the axial direction,
The structure is such that the rotation of the shaft 16 allows fluid on the atmospheric side to easily flow in through the groove 25.

As mentioned above, the embodiment in which the groove is provided on the circumferential side is
If there is a lot of dust in the atmosphere surrounding the sealing device,
Since dust tends to enter when fluid is sucked into the annular cavity, it can be expected that this intrusion can be effectively prevented. Further, the sealing performance of each seal portion is maintained, and friction, wear, etc. are effectively prevented.

[Brief explanation of the drawing]

FIG. 1 is a half cross-sectional view of a conventional oil seal.
The figures are half sectional views of a conventional dust trip, Fig. 3 is a half sectional view of the sealing device of the present invention, Fig. 4 is a half sectional view of the dust trip of Fig. 3 where the protruding portion of the dust trip comes into contact with the shaft to form a passage, Fig. 5 is a front view of the dust trip of the sealing device of the present invention where a passage is formed, Fig. 6 is a half sectional view of a sealing device showing another embodiment of the present invention, and Fig. 7 is a sectional view of one embodiment of the dust trip of the present invention. 1...Outer periphery, 2...Dust trip, 3...Oil seal, 4...Main trip, 5...Base, 6...
...shaft, 7...annular space, 8...hole, 9...support portion, 11...reinforcing ring, 12...dust strip, 1
3: sealing device, 14: main lip, 15: base, 16: shaft, 17: annular space, 18: fixing portion, 19: support portion, 20: seal portion, 21
...seal portion, 22...spring, 23...peripheral surface, 24...projection portion, 25...groove portion, 30...
aisle.

Claims (1)

[Scope of utility model registration request] A fixing portion 18 fixed to the circumferential surface of one of the hole and the shaft that are concentrically combined with each other, and the fixing portion 18
An annular space 17 is formed between a base 15 integrally connected to the base 15, a dust strip 12 made of a rubber-like elastic material extending from the base 15 and inclined with respect to the axis, and the dust strip 12 extending from the base 15. The dust lip 12 has a main lip 14 made of a rubber-like elastic material, and the dust lip 12 is located on the end peripheral side and
6 a seal portion 20 in contact with the circumferential surface, and a groove portion 25 or a convex portion disposed on the circumferential surface 23 on the side of the annular space 17 and formed from the vicinity of the seal portion 20 toward the base portion 15 side. 24, and by generating negative pressure in the annular space 17, the side circumferential surface of the groove portion 25 or the convex portion 24 is moved toward the other member 1.
A sealing device that contacts the circumferential surface of the other member 16 and forms a passage 30 that communicates with the annular space 17 and the atmosphere between the circumferential surface of the other member 16 and the side surface of the groove portion 25 or the convex portion 24.