Seal for a joint or juncture – Seal between relatively movable parts – Piston ring or piston ring expander or seat therefor
Reexamination Certificate
1998-02-26
2003-04-08
Knight, Anthony (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Piston ring or piston ring expander or seat therefor
C277S437000, C277S549000, C277S560000, C277S562000
Reexamination Certificate
active
06543783
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The invention relates to a sealing ring, comprising a sealing body with a dynamically stressed sealing lip made of an elastomeric material which at least partially encloses a toroidal supporting body, with the supporting body having a slope facing the sealing lip. The sealing body has a dynamically stressed sealing bulge which is adjacent to it with an axial distance on the side facing away from the space to be sealed and which is in contact with the area to be sealed under an initial elastic stress.
BACKGROUND OF THE INVENTION
One example of a sealing ring of the general type to which this invention is directed is disclosed in German Patent DE 39 37 896 A1. That sealing ring is designed as a lip seal gasket, with the sealing body and the supporting body force-locked together. The supporting body is arranged inside the sealing body and should prevent radial expansion of the sealing body past the supporting body and a resulting radial shearing of the sealing body away from the supporting body.
SUMMARY OF THE INVENTION
The object of this invention is to improve on a sealing ring of this type so that the sealing ring has improved use properties and a longer service life. To that end, the sealing ring has a sealing bulge that particularly enhances the sealing properties of the device.
This object is achieved by arranging the sealing bulge between the two radial planes in the axial direction which bound the slope of the torroidal sealing body. It is advantageous that the sealing bulge be axially supported by the sloped portion of the supporting body in the area of its contact point with the face to be sealed. The support of the sealing bulge by the slope and its elastic adaptation to the face to be sealed are almost constant during the entire useful life of the sealing ring. The design of the supporting body and its association with the sealing bulge have the effect that the elastomeric material is not exposed to any bending moments, compression and/or tensile stresses in the area of the sealing bulge which would reduce its service life. Due to the fact that the sealing bulge is covered by the slope of the supporting body in the axial direction, there is a great dissipation of stress within the elastomeric material in the area of the slope—compared to supporting bodies without a slope on the side facing the sealing lip—so that shearing away or detachment of the elastomeric material from the supporting body is reliably prevented. The dissipation of stress also affects the bonding layer between the elastomeric material and the supporting body.
According to one advantageous embodiment, the ratio of the width of the slope to the width of the supporting body is 0.2 to 0.7, preferably 0.3 to 0.5. It is advantageous here that with such a ratio, good support and guidance of the sealing bulge and an adequately great dissipation of stress within the elastomeric material in the area of the slope are achieved.
The stresses within the elastomeric material are greater when a traditional supporting body, which is largely rectangular in shape in the area of the sealing bulge, is employed, as in the prior art, than with a design having a slope as set forth here.
According to a first embodiment, the slope may be designed as a chamfer. The chamfer may have an angle &agr; of 20° to 45°, preferably 30° to 45°, with respect to the axis. Such a chamfer can be produced easily and inexpensively from the point of view of the manufacturing technology.
According to another embodiment, the slope may be designed as an arch curved in the direction of the sealing lip. The stresses are largely uniformly distributed along the arch and are at most approximately two-thirds as great in comparison with a slope designed as a chamfer.
All the edges of the supporting body enclosed by the elastomeric material are preferably rounded, with the edges each having a radius of at least 0.3 mm. It is advantageous here that stress peaks within the elastomer sealing body in the area of the edges of the supporting body are minimized. The danger of detachment of the elastomeric material from the supporting body, which is made of a tough hard material, e.g., a metallic material, is thus further reduced.
The side of the supporting body facing toward the face to be sealed may form an angle &bgr; of 5° to 20°, preferably 7° to 15° with the axis, and the first end face turned away from the sealing lip may be brought closer to the surface to be sealed than the second end face which faces the sealing lip. Such an embodiment contributes to a further reduction in stresses in the elastomeric material of the sealing ring regardless of whether the slope is designed as a chamfer or as an arch. With regard to achieving the most uniform possible distribution of stresses within the elastomeric material, it is advantageous that changes in direction in the surface of the supporting body take place as gradually as possible and with the largest possible radii.
In cross section, the sealing body has a trapezoidal enlargement between the radial planes axially in the direction of the sealing lip. Due to the trapezoidal transition of the elastomeric material of the sealing bulge in the direction of the sealing lip, the cross section of the sealing body increases steadily. The service life of the sealing ring is further improved due to the fact that there is no reduction in cross section.
The side of the sealing body facing the surface to be sealed preferably forms an angle &khgr; of 5° to 15°, and preferably 7° to 10° with respect to the axis, from the end face which is turned axially away from the sealing lip to the sealing bulge, with the surface to be sealed and the sealing body bordering a wedge-shaped gap that tapers from the end face in the direction of the sealing bulge. Such a design yields a good return flow of the medium to be sealed used to lubricate the sealing lip and the sealing bulge in the direction of the space to be sealed with a translational movement of the surface to be sealed relative to the sealing ring.
The sealing lip and the sealing bulge are each preferably bordered by two intersecting conical surfaces, with the conical surfaces facing the space to be sealed forming a larger angle with the axis than do the conical surfaces facing away from the space to be sealed. According to the effect of the angle &khgr; described above, excellent sealing of the space to be sealed is achieved with such an embodiment of the sealing lip and sealing bulge with machine parts moving with a translational movement relative to one another. Furthermore, good lubrication of the sealing lip and sealing bulge is achieved. The medium to be sealed, which serves to lubricate the sealing lip and sealing bulge, is returned to the space to be sealed with the back and forth movement of the machine parts due to the shallow angle of the conical faces that face away from the space to be sealed.
The sealing ring according to the invention is preferably designed as a lip seal for sealing two machine parts such as gear pistons that are engaged in a translational movement relative to one another. The sealing lip may be arranged in a groove that is open to the outside in a rod, depending on the respective application, and a casing which surrounds the rod radially on the outside comes in contact with its sealing lip and the sealing bulge under an initial elastic stress. According to another embodiment, it is possible for the sealing ring to be arranged in a groove which is open toward the inside radially in a casing and to surround and seal with its sealing lip and the sealing bulge a rod guided through the casing.
REFERENCES:
patent: 4298203 (1981-11-01), Holzer
patent: 4410190 (1983-10-01), Potter
patent: 4504068 (1985-03-01), Holzer
patent: 393 7896 (1991-05-01), None
Bergmann Günter
Freitag Edgar
Firma Carl Freudenberg
Kenyon & Kenyon
Peavey Enoch
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