Frictionless shaft seal
A sealing element for sealing a shaft comprises a stiffening part, a first elastomer part connected to the stiffening part and adapted to adjoin the housing part and provide a static seal relative, and a second elastomer part of an elastomer material different from the elastomer material forming the first elastomer part. The second elastomer part is connected to the stiffening part and comprises a sealing section adapted to adjoin the shaft to seal a space. The sealing section comprises a return structure for returning a leaking fluid to a space to be sealed. The sealing section also comprises a region at one axial end portion of the sealing section which is peripherally closed in itself and extends along an inner surface of a circular cylinder portion of the sealing section that is adapted to adjoin and seal the shaft as the shaft is not turning.
1. A sealing element in combination with a housing part and a shaft which is rotatable at a passage opening of the housing part, the sealing element being positioned between the housing part and the shaft to seal the shaft, the sealing element comprising:
a stiffening part,
a first elastomer part contacting the housing part and providing a static seal relative to the housing part;
the first elastomer part being made of a first elastomer material and being connected to the stiffening part;
a second elastomer part of a second elastomer material which is different from the first elastomer material;
the second elastomer part being connected to the stiffening part;
the second elastomer part comprising a sealing section contacting the shaft to provide a static seal relative to the shaft to seal a space to be sealed from an outside, the sealing section possessing an inside surface facing the shaft, the second elastomer part including a flared section which flares radially outwardly away from the shaft;
at least three grooves provided on the inside surface of a circular cylinder portion of the sealing section to permit fluid return toward the space to be sealed;
the at least three grooves being circumferentially spaced apart on the inside surface of the circular cylinder portion of the sealing section;
each of the at least three grooves having a first end located closer to the flared section and an opposite end farther from the flared section, the first end of each of the at least three grooves terminating at a region at one axial end portion of the circular cylinder portion of the sealing section which is peripherally closed in itself such that the first end of each of the three grooves terminates at a portion of the circular cylinder portion of the sealing section in contact with the shaft;
wherein the second elastomer part comprises a fluoroelastomer,
wherein the second elastomer part comprises a secondary sealing lip arranged in contacting relationship the shaft and made of a material which provides a breathing activity or filter effect while adjoining the shaft, and
wherein at least two of the grooves are arc-shaped and cross each other without connecting the space to be sealed with the outside.
2. The sealing element as claimed in claim 1 , wherein the first and second elastomer parts do not directly adjoin one another.
3. The sealing element as claimed in claim 1 , wherein at least one of the elastomer parts is vulcanized onto the stiffening element.
4. The sealing element as claimed in claim 1 , wherein the secondary sealing lip is integrally formed in one-piece as a part of the second elastomer part.
5. The sealing element as claimed in claim 4 , wherein the secondary sealing lip is made from a nonwoven material.
6. The sealing element as claimed in claim 1 , wherein the stiffening part adjoins the housing part.
7. The sealing element as claimed in claim 1 , wherein the one region at the one axial end portion of the circular cylinder portion of the sealing section which is peripherally closed in itself is configured as a circular ring.
8. The sealing element as claimed in claim 1 , wherein the sealing element is configured such that the flared section narrows radially inwardly as it approaches the space to be sealed.
9. The sealing element as claimed in claim 1 , wherein at least one of the grooves possesses a shape of a sickle which narrows in width towards one end of the groove.
10. The sealing element as claimed in claim 1 , wherein one of the grooves is made extending in a segment of the sealing section and has a peripheral angle of less than or equal to 120°.
11. The sealing element as claimed in claim 1 , wherein at least one of the grooves possessing a width that increases to an axial side to which fluid return is permitted.
12. The sealing element as claimed in claim 1 , wherein at least one of the grooves terminates as a ramp into the region which is peripherally closed in itself.
13. The sealing element as claimed in claim 1 , wherein the grooves exist between crosspieces that contact the shaft, the crosspieces are located in the sealing region in a circular cylinder.
14. The sealing element as claimed in claim 1 , wherein the sealing section which adjoins the shaft is a hollow cylinder.
15. The sealing element as claimed in claim 1 , wherein the sealing element is a radial shaft gasket.
16. The sealing element as claimed in claim 1 wherein the radial thickness of the one region of the sealing section which is peripherally closed in itself is 0.4 mm to 0.55 mm.
17. The sealing element as claimed in claim 16 wherein at least one of the grooves possesses a shape of a sickle which narrows in width towards one end of the groove.
18. The sealing element as claimed in claim 1 , wherein the first elastomer material is one of AEM (ethylene-acrylic elastomer), ACM ((poly)acrylate/acrylic elastomer), EVM (ethylene vinyl acetate copolymer) or silicone.