Hydrodynamic sealing element for a radial shaft seal
A hydrodynamic sealing element for a radial shaft seal includes a radial flange leg encircling a rotation axis and an oblique flange leg encircling the rotation axis and joined to the radial flange leg. The oblique flange leg extends both radially inward and axially away from the radial flange leg to form an oblique angle relative to the radial flange leg. The oblique flange leg has an air-side surface and an end face that meet at a lip. The oblique flange forms a plurality of hydrodynamic indentations that extend into the oblique flange leg from the air-side surface. The sealing element may be formed from leather, in which case the indentations may be created by debossing the leather. The sealing element may be inserted into a seal case to create a radial shaft seal.
1. A hydrodynamic sealing element for a radial shaft seal, comprising:
a radial flange leg encircling a rotation axis; and
an oblique flange leg encircling the rotation axis and joined to the radial flange leg, the oblique flange leg extending both radially inward and axially away from the radial flange leg to form an oblique angle relative to the radial flange leg, the oblique flange leg having an air-side surface and an end face that meet at a lip;
wherein the oblique flange leg forms a plurality of hydrodynamic indentations that extend into the oblique flange leg from the air-side surface;
wherein the edges of each hydrodynamic indentation that intersect the air-side surface form a triangle having an apex and a base, and the apex is closer to the lip than the base.
2. The hydrodynamic sealing element of claim 1 , comprising leather.
3. The hydrodynamic sealing element of claim 1 , the plurality of hydrodynamic indentations being formed by debossing.
4. The hydrodynamic sealing element of claim 1 , the plurality of hydrodynamic indentations being distributed uniformly about the rotation axis.
5. The hydrodynamic sealing element of claim 1 , a number of the plurality of hydrodynamic indentations being between five and twelve.
6. The hydrodynamic sealing element of claim 1 , all of the plurality of hydrodynamic indentations having the same shape.
7. The hydrodynamic sealing element of claim 1 , wherein:
each of the plurality of hydrodynamic indentations is shaped as a tetrahedron.
8. The hydrodynamic sealing element of claim 7 , wherein:
the triangle is an isosceles triangle.
9. The hydrodynamic sealing element of claim 7 , the apex having an apex angle greater than ninety degrees.
10. The hydrodynamic sealing element of claim 7 , a shortest distance between the apex and the lip being less than 0.02 inches.
11. The hydrodynamic sealing element of claim 1 , wherein:
each of the plurality of hydrodynamic indentations is shaped as a tetrahedral shell; and
edges of the tetrahedral shell that intersect the air-side surface form a triangular annulus.
12. The hydrodynamic sealing element of claim 1 , wherein:
respective pairs of hydrodynamic indentations are shaped as a double tetrahedron; and
edges of the double tetrahedron that intersect the air-side surface form a double triangle.
13. The hydrodynamic sealing element of claim 12 , wherein:
the double triangle comprises a first triangle having a first apex and a first base;
the double triangle comprises a second triangle having a second apex and a second base;
the first triangle and the second triangle have the same area;
the first base and the second base are co-linear and share a base vertex;
the first base is closer to the lip than the first apex; and
the second base is closer to the lip than the second apex.
14. The hydrodynamic sealing element of claim 1 , the end face forming a sinusoidal pattern around a circumference of the flange seal such that an axial position of the lip varies sinusoidally about the rotation axis.
15. The hydrodynamic sealing element of claim 1 , the radial flange leg forming a relief groove where the radial flange leg meets the oblique flange leg.
16. The hydrodynamic sealing element of claim 1 , the oblique flange leg and the radial flange leg having a similar thickness.
17. A radial shaft seal, comprising:
the hydrodynamic sealing element of claim 1 ; and
a seal case encircling the rotation axis, the seal case comprising an inner frame, an outer frame, and a spacer between the inner frame and the outer frame, the spacer pushing the radial flange leg of the flange seal against the outer frame.
18. The radial shaft seal of claim 17 , further comprising a sleeve with a radially outward-facing sleeve surface, the lip of the flange seal contacting the radially outward-facing surface to form a sealing region.
19. The radial shaft seal of claim 18 , further comprising a garter spring encircling the oblique flange leg, the garter spring being axially positioned to radially compress the lip against the radially outward-facing sleeve surface.