JPS5884268A - Self-venting seal assembly - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Ru.

More particularly, the present invention relates to seals for venting pressurized gas from a lubricant housing to the environment, particularly for use in bearing assemblies.

Bearing assemblies, particularly vehicle wheel bearing assemblies, commonly include garter spring type seals to retain lubricant within a lubricant housing. A problem with such bearing assemblies is that pressure fluid or gas forms within the lubricant housing, resulting in significant pressures and temperatures within the lubricant housing.

The present invention aims to solve this problem.

In accordance with the present invention, a rotating shaft extends from a lubricant housing in which a pressurized gas is formed, and a seal is arranged to retain the lubricant within the lubricant housing while venting the pressurized gas therefrom to the surroundings. a flexible wall connecting the generally annular body portion to a sealing lip having a lubricant side, a peripheral side, and a top portion in sealing contact with the rotating shaft; a biasing resilient means and a circumferential series of venting protrusions extending radially inwardly toward the axis of rotation proximate the top of the sealing lip on its periphery, each protrusion extending radially inwardly toward the axis of rotation; The differential pressure between the surroundings and the gas pressure in the lubricant housing, created before and after a deflecting wall in operation, causes the flexible wall to rotate around the axis of rotation. and rotate the sealing lip in the axial and radial direction of the rotating shaft against the bias of the elastic means to move the pad of the vent protrusion radially inward to engage the rotating shaft and sealing. The top of the lip is pushed away from the axis of rotation to allow the pressure gas to escape along the axis of rotation between the venting projections to the surroundings, said elastic means displacing the top of the sealing lip after venting of the pressure gas to the surroundings. A self-venting seal assembly is provided which is characterized in that the pad is returned to sealed contact with the rotating shaft and the pad is removed from the rotating shaft.

In a particular arrangement of the invention, a garter spring type seal for a bearing assembly is arranged to vent pressurized fluid and gas from the lubricant housing to the environment across the seal to relieve excess pressure. The seal includes a sealing lip that is held in contact with the rotating shaft by a garter spring to seal the lubricant housing from its surroundings. The seal further includes a flexible wall connecting the sealing lip to the fixed body of the seal.

A series of circumferentially spaced vent projections are provided on the circumferential side of the sealing lip. These projections extend toward the axis and terminate in pads located at very shallow angles to the axis. When the pressure of the gas generated within the lubricant housing reaches a predetermined limit, the differential pressure across the flexible wall causes the sealing lip to rotate radially outwardly in the axial direction of the shaft. This movement of the sealing lip engages the vent lug pad with the shaft and forces the sealing lip away from the shaft against the force of the garter spring. The pressurized gas then escapes along the axis between the protrusions to the periphery. When the pressure inside the lubricant reservoir falls below a predetermined limit, the garter spring returns the sealing lip to sealing engagement with the shaft.

EMBODIMENT OF THE INVENTION Hereinafter, the present invention will be explained by Example 1 with reference to the accompanying drawings.

In the embodiment of the self-venting seal assembly according to the present invention shown in Figures 1-3, the garter spring type seal, generally designated 10, has a metal mounting case 12f?
! The case is shown schematically and is typically a press fit within the bore of a lubricant housing 14 as conventionally found in bearing assemblies.

The case 12 is molded into a plastic annular seal body 16. The seal further includes a sealing lip 1
B, which lip is in contact with an inner wall 20 located in the lubricant reservoir, a flexible wall 22 connecting the sealing lip 18 to the body portion 16, and a rotatable shaft 26, shown schematically, to contain the lubricant. a ribbed annular sealing top 24 for retaining the lubricant within the lubricant reservoir 14. A garter spring 28 surrounds the sealing lip 18 and maintains the top 24 of the sealing lip 18 in sealing contact with the shaft 26.

The pressure gas formed within the lubricant reservoir 14 typically
No escape is possible through the sealing top 24. To vent this gas, the seal 10 according to the invention includes a series of circumferentially spaced venting projections 30;
These protrusions are integrally molded around the sealing lip 18. The protrusions 30 are generally chordal or arcuate in shape (and thus sector-shaped) and each include an arcuately curved wall 32 and a circumferentially linear wall 34 facing the circumferential side of the seal. Wall 32 is tangential to sealing top 24, as best seen in FIG.

The walls 32 , 34 define a circumferentially arcuate pad 36 located at a shallow angle of about 2 to 4 degrees with respect to the axis 26 . Normally, only the sealing top 24 and the portion of the wall 32 tangential thereto are engaged with the rotating shaft 26, and the pad 36 is not engaged with the shaft 26.

The operation of this vent protrusion 30 will be explained below with reference to FIG. The pressure of the gas built up in the lubricant reservoir 14 creates a pressure differential across the flexible wall 220, thereby pushing this wall 22 radially toward the axis 26,
The sealing lip 18 is rotated axially and radially outwardly of the shaft 26 against the force of the garter spring 28. This seats the pad 36 on the shaft 26 and forces or moves the sealing top 24 of the lip 18 radially outwardly on the shaft, directing the pressurized gas between the projections 300 along the shaft 26 to the surroundings (i.e., the atmosphere). to release the lubricant from the reservoir. After the pressure gas has sufficiently escaped and the pressure difference across the flexible wall 22 is reduced, the garter spring 28 is attached to the flexible wall 2.
20 elastically returns the sealing top 24 to its normal position in sealing engagement with the shaft 26 and the ventilation projection 30 to its normal position as shown.

In the illustrated embodiment, there are six protrusions 30.

The number of protrusions may be increased or decreased if the protrusions are capable of displacing or moving the r-seal top 24 radially outwardly of the shaft against the force of the garter spring. The pressure at which the pressurized gas vents is applied to the wall 22 relative to the body portion 16.
, the size of the sealing lip 18 , the force of the spring 28 , and the angle between the pad 36 of the vent projection 30 and the axis of rotation 26 . The greater the spring force and the stiffer the wall 22, the greater the angle of the pad 36 with respect to the axis 26, resulting in a higher vent pressure.

Figures 4-6 are a second embodiment of a self-venting seal assembly according to the present invention. In this embodiment, the garter spring type seal 10 includes a sealing lip 18 of the same configuration as in the previous embodiment and similarly seals lubricant within the lubricant reservoir 14. The only difference is the form of the six vent projections shown at 38.

In this embodiment, the protrusion has a substantially rectangular shape, unlike the arcuate shape of the previous embodiment.

Details regarding the shape of protrusion 38 and its operation can be understood by referring to Figure 5.6. Each protrusion 38 extends between an inner linear wall 40 facing the lubricant reservoir 14 and an outer linear wall 42 facing the periphery, and extends between these walls.
6 and a pad 44 forming a shallow angle of 2 to 4 degrees.

The operation of this seal 10 is similar to that of the first embodiment. In response to the pressure differential between the gas formed in lubricant reservoir 14 and the surroundings, sealing lip 18 moves radially inwardly toward shaft 26 as flexible wall 22 moves radially inwardly toward shaft 26 .
0 radially, axially outwardly bulges or rotates. This seats the pad 44 of the venting projection 38 on the shaft 26 and forces or moves the sealing top 24 of the lip 1.8 radially outwardly of the shaft against the force of the spring 28 to direct the pressurized gas onto the shaft. 38 along axis 26 from lubricant reservoir 14 to the surroundings.

Once the gas escapes, the force of spring 2B, together with the elasticity of deflectable wall 22, returns sealing top 24 to its normal position in sealing engagement with shaft 26, and venting projection 38 to its normal position as shown.

The self-venting seal assembly according to the present invention that has been described provides a self-venting seal for a bearing assembly that vents pressurized gas and fluids built up in a lubricant reservoir to the environment. This vented seal includes venting projections on the circumferential side of the sealing lip that are forced into contact with the shaft under the differential pressure between the gas in the lubricant reservoir and the surroundings. is used to selectively push the sealing lip away from the shaft, allowing gas to escape to the surroundings. In this self-venting seal, after the gas has escaped to the environment, the sealing lip returns to sealing contact with the shaft without excessive loss of lubricant.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of one embodiment of a self-venting seal assembly according to the present invention. FIG. 2 is a fragmentary enlarged cross-sectional view showing the seal of this assembly in the pressurized position. FIG. 3 is a view similar to FIG. 2 showing the seal in the vented position. FIG. 4 is a longitudinal cross-sectional view of another embodiment of a self-venting seal assembly according to the present invention. FIG. 5 is a fragmentary, enlarged cross-sectional view of the embodiment of FIG. 4 showing the seal in an unpressurized position. FIG. 6 is a view similar to FIG. 5 showing the seal in the vented position. [Explanation of symbols of main parts] 10...Seal, 12...Mounting case, 14
...Lubricant reservoir, 16...Main body, 18...
Sealing lip, 22...Flexible wall, 24...
-Top of sealing lip, 26... Rotating shaft, 28... Garter spring, 30.38... Bent projection, 36.44... Pad 40.42... Linear wall.

Claims (1)

[Claims] 1. A rotating shaft extends from a lubricant housing in which a pressurized gas is formed, and a seal is arranged to retain the lubricant within the lubricant housing while venting the pressurized gas therefrom to the surroundings. In a self-venting seal assembly, the seal (e.g. 10) includes a generally annular body portion (e.g. 16).
a flexible wall (e.g. 2) connected to a sealing lip (e.g. 18) with a lubricant side, a peripheral side and a top (e.g. 24) in sealing contact with said rotating shaft (e.g. 26).
2); a resilient means (e.g. 28) for biasing the sealing lip toward the axis of rotation; a circumferential series of vent projections (e.g. 30)
, each protrusion having a pad (e.g. 36) positioned at a shallow angle relative to the axis of rotation, and in actuation forming a periphery and a pad (e.g. 14) on the front and rear of the flexible wall. ) forces the flexible wall towards the axis of rotation and causes the sealing lip to rotate in the axial and radial direction of the axis of rotation against the bias of the elastic means. to move the pads of the venting lugs radially inward into engagement with the axis of rotation and displacing the top of the sealing lip away from the axis of rotation between the venting lugs along the axis of rotation. allowing the pressurized gas to escape to the surroundings, the resilient means returning the top of the sealing lip to sealing contact with the rotating shaft and disengaging the pad from the rotating shaft after venting the pressurized gas to the surroundings; A self-venting seal assembly featuring: 2. A self-venting seal assembly according to claim 1, in which differential pressure pushing said flexible wall (e.g. 22) toward said axis of rotation causes said sealing lip (e.g. 18) to A self-venting seal assembly characterized by axial rotation radially outwardly of the shaft. 3. A self-venting seal assembly according to claim 1 or 2, wherein each of the venting protrusions (e.g. 30) is fan-shaped, and the curved wall of each protrusion (
32) is tangential to the top (eg 24) of the sealing lip (eg 11). 4. A self-venting seal assembly according to claim 1 or 2, wherein each of the venting projections (e.g. 38) is rectangular and the top of the sealing lip (35 e.g. 24) a first circumferential linear wall (e.g. 40) and a second circumferential linear wall (e.g. 42) adjacent to each other, and a respective pad (e.g. 44) extending between the first and second walls. A self-venting seal assembly characterized by an extension.