CA2457167A1 - Sealing ring and seal arrangement including two such sealing rings - Google Patents
Sealing ring and seal arrangement including two such sealing rings Download PDFInfo
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- CA2457167A1 CA2457167A1 CA002457167A CA2457167A CA2457167A1 CA 2457167 A1 CA2457167 A1 CA 2457167A1 CA 002457167 A CA002457167 A CA 002457167A CA 2457167 A CA2457167 A CA 2457167A CA 2457167 A1 CA2457167 A1 CA 2457167A1
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Abstract
A sealing ring is disclosed for the sealing of a space to be sealed about a machine element to be sealed. The sealing ring includes a sealing collar made of elastomeric material; at least one sealing lip on the sealing collar for sealing the space to be sealed; a stiffening ring of tough ductile material connected with the sealing collar. The sealing collar when viewed in longitudinal section of the sealing ring, has a radially outer axial leg connected with the stiffening ring only on the side axially facing the space to be sealed and a radial leg. The sealing ring further includes supporting ring connected with the stiffening ring and associated without bonding with an outer circumferential surface of the outer axial leg and an end face of the radial leg axially facing away from the space to be sealed. The supporting ring has a radial flange which is closely spaced from a surface of the machine element to be sealed with a very small intermediate radial spacing. Further disclosed is a sealing arrangement including a first sealing having a first sealing collar of elastomeric material with at least one sealing lip for the sealing of a first space to be sealed about a machine element to be sealed and a first supporting ring of tough ductile material connected with the sealing collar and having a first radial flange and a first axial flange;
and a second sealing ring having a second sealing collar of elastomeric material with at least one sealing lip for the sealing of a second space to be sealed axially adjacent the first space to be sealed and a second supporting ring of tough ductile material connected with the sealing collar and having a second radial flange and a second axial flange; whereby the first and second sealing rings are combined into a pre-assembled unit.
and a second sealing ring having a second sealing collar of elastomeric material with at least one sealing lip for the sealing of a second space to be sealed axially adjacent the first space to be sealed and a second supporting ring of tough ductile material connected with the sealing collar and having a second radial flange and a second axial flange; whereby the first and second sealing rings are combined into a pre-assembled unit.
Description
SEALING RING AND SEAL ARRANGEMENT INCLUDING TWO SUCH
SEALING RINGS
FIELD OF THE INVENTION
The invention relates to a sealing ring including a sealing collar of elastomeric material with at least one sealing lip for the sealing of a space to be sealed, whereby the sealing collar is connected to a stiffening ring of tough, viscous material.
BACKGROUND ART
Such sealing rings are generally known and are used, for example, as radial shaft seals. The sealing collar and the stiffening ring are thereby vulcanized together, whereby the sealing collar in the region of the sealing lip is flexible in radial direction. Especially in radial shaft seals with an axially short sealing collar for the sealing of pressurized media, the comparatively small flexibility/large stiffness is not satisfactory for many applications, since, for example, out-of round movement of the machine part to be sealed and/or wear of the sealing lip during operation can only be insufficiently compensated by the sealing ring. To partially compensate for this construction defect, the known sealing rings are installed with relatively large radial overlap, which means the sealing lip is manufactured to have a significantly smaller diameter than the surface of the machine element to be sealed. Such a large radial overlap leads however to a high friction moment during operation and to an undesirable early wear of the sealing lip.
SUMMARY OF THE INVENTION
It is an object of the invention to further develop a sealing ring of the above-mentioned type such that it provides improved use properties over an extended period of use. In particular, the friction moment between the sealing collar and the machine element to be sealed is to be reduced. Eccentricity and/or out-of round running of the machine element to be sealed are to be compensated better by way of an enlarged range of movement of the sealing lip. Furthermore, the sealing ring is to be manufactured simpler and at lower cost from the standpoint of manufacturing technology and economy.
In addition, the sealing ring is to be usable for the sealing of higher pressures, far example in
SEALING RINGS
FIELD OF THE INVENTION
The invention relates to a sealing ring including a sealing collar of elastomeric material with at least one sealing lip for the sealing of a space to be sealed, whereby the sealing collar is connected to a stiffening ring of tough, viscous material.
BACKGROUND ART
Such sealing rings are generally known and are used, for example, as radial shaft seals. The sealing collar and the stiffening ring are thereby vulcanized together, whereby the sealing collar in the region of the sealing lip is flexible in radial direction. Especially in radial shaft seals with an axially short sealing collar for the sealing of pressurized media, the comparatively small flexibility/large stiffness is not satisfactory for many applications, since, for example, out-of round movement of the machine part to be sealed and/or wear of the sealing lip during operation can only be insufficiently compensated by the sealing ring. To partially compensate for this construction defect, the known sealing rings are installed with relatively large radial overlap, which means the sealing lip is manufactured to have a significantly smaller diameter than the surface of the machine element to be sealed. Such a large radial overlap leads however to a high friction moment during operation and to an undesirable early wear of the sealing lip.
SUMMARY OF THE INVENTION
It is an object of the invention to further develop a sealing ring of the above-mentioned type such that it provides improved use properties over an extended period of use. In particular, the friction moment between the sealing collar and the machine element to be sealed is to be reduced. Eccentricity and/or out-of round running of the machine element to be sealed are to be compensated better by way of an enlarged range of movement of the sealing lip. Furthermore, the sealing ring is to be manufactured simpler and at lower cost from the standpoint of manufacturing technology and economy.
In addition, the sealing ring is to be usable for the sealing of higher pressures, far example in
2 the range of up to 200 bar. The sealing collar is to be always exactly positioned relative to the components of the sealing ring, and gap extrusion and a damaging/destruction of the material of the sealing collar resulting therefrom is to be avoided.
This object is achieved in accordance with the invention in that the sealing collar, when viewed in longitudinal section of the sealing ring, has a radially outer and a radially inner axial leg, whereby the axial legs are connected by a radial leg on that side directed in axial direction away from the space to be sealed, that the outer axial leg is connected with the stiffening ring only on that side directed axially towards the space to be sealed, that the outer circumferential surface of the outer axial leg and the end face of the radial leg directed axially away from the space to be sealed are associated with a supporting ring without bonding and that the supporting ring has a radial flange which is positioned at a small radial distance closely spaced apart from the surface of the machine part to be sealed to form a radial gap. By way of this construction, the sealing lip, relative to sealing rings in which the sealing lip is positioned in the immediate vicinity of the stiffening ring and connected therewith by vulcanization, has a comparatively large range of movement, especially in radial direction, to compensate for eccentricities of the machine element to be sealed. Furthermore, by way of the unbonded connection of the outer axial leg and the radial leg with the supporting ring and the larger range of movement resulting therefrom, the friction moment between the sealing lip and the machine element to be sealed is reduced. This is an advantage which must be pointed out with respect to good use properties over a very long period of use; the abrasion wear of the sealing lip, compared to the afore-described sealing ring of the art, is significantly reduced. Because of these advantageous use properties, the sealing ring in accordance with the invention is especially well suited also for the sealing of elevated pressures. For example, if the sealing ring is used as a pump seal, pump pressures of, for example, up to 200 bar can be sealed without difficulty.
According to a preferred embodiment, the sealing collar, when viewed in longitudinal section of the sealing ring, is essentially C shaped and axially open in direction of the space to be sealed.
It is an advantage of the very small radial spacing of the radial flange of the supporting ring from the surface of the machine element to be sealed, whereby the radial width of the radial gap is 0.01 to 0.2 mm, preferably 0.03 to 0.12 rnm, that even v,Then high
This object is achieved in accordance with the invention in that the sealing collar, when viewed in longitudinal section of the sealing ring, has a radially outer and a radially inner axial leg, whereby the axial legs are connected by a radial leg on that side directed in axial direction away from the space to be sealed, that the outer axial leg is connected with the stiffening ring only on that side directed axially towards the space to be sealed, that the outer circumferential surface of the outer axial leg and the end face of the radial leg directed axially away from the space to be sealed are associated with a supporting ring without bonding and that the supporting ring has a radial flange which is positioned at a small radial distance closely spaced apart from the surface of the machine part to be sealed to form a radial gap. By way of this construction, the sealing lip, relative to sealing rings in which the sealing lip is positioned in the immediate vicinity of the stiffening ring and connected therewith by vulcanization, has a comparatively large range of movement, especially in radial direction, to compensate for eccentricities of the machine element to be sealed. Furthermore, by way of the unbonded connection of the outer axial leg and the radial leg with the supporting ring and the larger range of movement resulting therefrom, the friction moment between the sealing lip and the machine element to be sealed is reduced. This is an advantage which must be pointed out with respect to good use properties over a very long period of use; the abrasion wear of the sealing lip, compared to the afore-described sealing ring of the art, is significantly reduced. Because of these advantageous use properties, the sealing ring in accordance with the invention is especially well suited also for the sealing of elevated pressures. For example, if the sealing ring is used as a pump seal, pump pressures of, for example, up to 200 bar can be sealed without difficulty.
According to a preferred embodiment, the sealing collar, when viewed in longitudinal section of the sealing ring, is essentially C shaped and axially open in direction of the space to be sealed.
It is an advantage of the very small radial spacing of the radial flange of the supporting ring from the surface of the machine element to be sealed, whereby the radial width of the radial gap is 0.01 to 0.2 mm, preferably 0.03 to 0.12 rnm, that even v,Then high
3 pressures are sealed, the material of the sealing collar is not extruded into the radial gap to an undesirably large degree. The sealing ring therefore has consistently good use properties over a long period of use.
The supporting ring preferably consists of a polymeric material, for example POM
(polyoxymethylene) or a PTFE (polytetrafluoroethylene) compound. Especially when the radial gap has only a very small radial width, a supporting ring consisting of a self lubricating material is meaningful. Should the opposing surfaces of the sealing ring and the machine element to be sealed come into contact during the intended use of the sealing ring, such a contact does not lead to damage/destruction of the mutually contacting components; the components would then contact one another only with very low friction.
Especially with a very small radial gap between the supporl:ing ring and the shaft, the supporting ring can be constructed such that it extends in radial direction outwardly about as far as the sealing ring itself and can center itself thereby in the aggregate to be sealed. It is thereby advantageous that the position is exactly defined and centered. The gap width is constant over the whole circumference.
A further reduction of the risk of gap extrusion can be achieved by providing the radial flange on its side facing the surface of the element to be sealed with a supporting projection protruding axially in direction of the space to be sealed and at least partially extending under the sealing lip. This supporting projection supports the sealing lip even at exposure to pressures of about 200 bar.
Because of the reduced friction moment, the heat generation is necessarily relatively low, as well as the heat transfer to the medium to be sealed, which is, for example, a transmission oil or hydraulic oil. The low heat transfer to the medium to be sealed has a positive effect on the aging of the medium to be sealed and/or the decomposition or precipitation of the additives contained in the medium to be sealed.
According to an especially advantageous embodiment, it is provided that the outer circumferential surface arid the end surface are respectively spaced apart adjacent to the supporting ring and engageable therewith. Such a construction is preferred within the framework of the present invention, since a sealing ring constructed in this manner solves the object mentioned above especially well. The outer circumferential surface specifically creates the advantageous use properties, which outer circumferential surface is radially spaced apart and adjacent to an axial flange of the supporting ring, whereby the radial
The supporting ring preferably consists of a polymeric material, for example POM
(polyoxymethylene) or a PTFE (polytetrafluoroethylene) compound. Especially when the radial gap has only a very small radial width, a supporting ring consisting of a self lubricating material is meaningful. Should the opposing surfaces of the sealing ring and the machine element to be sealed come into contact during the intended use of the sealing ring, such a contact does not lead to damage/destruction of the mutually contacting components; the components would then contact one another only with very low friction.
Especially with a very small radial gap between the supporl:ing ring and the shaft, the supporting ring can be constructed such that it extends in radial direction outwardly about as far as the sealing ring itself and can center itself thereby in the aggregate to be sealed. It is thereby advantageous that the position is exactly defined and centered. The gap width is constant over the whole circumference.
A further reduction of the risk of gap extrusion can be achieved by providing the radial flange on its side facing the surface of the element to be sealed with a supporting projection protruding axially in direction of the space to be sealed and at least partially extending under the sealing lip. This supporting projection supports the sealing lip even at exposure to pressures of about 200 bar.
Because of the reduced friction moment, the heat generation is necessarily relatively low, as well as the heat transfer to the medium to be sealed, which is, for example, a transmission oil or hydraulic oil. The low heat transfer to the medium to be sealed has a positive effect on the aging of the medium to be sealed and/or the decomposition or precipitation of the additives contained in the medium to be sealed.
According to an especially advantageous embodiment, it is provided that the outer circumferential surface arid the end surface are respectively spaced apart adjacent to the supporting ring and engageable therewith. Such a construction is preferred within the framework of the present invention, since a sealing ring constructed in this manner solves the object mentioned above especially well. The outer circumferential surface specifically creates the advantageous use properties, which outer circumferential surface is radially spaced apart and adjacent to an axial flange of the supporting ring, whereby the radial
4 spacing represents the radial stroke of the sealing lip, since the friction moment and the heat generation resulting therefrom is significantly reduced by the excellent flexibility of the sealing lip in radial direction, and the sealing lip can follow especially well eccentricities and/or out-of round movements of the machine element to be sealed.
According to another embodiment, the possibility exists that the outer circumferential surface contacts the supporting ring and that only the end surface is positioned spaced apart and adjacent to the supporting ring and engageable therewith.
Although a sealing ring constructed in this way compared to conventional sealing rings has more advantageous use properties because of the un-bonded connection of the outer axial leg to the axial flange of the supporting ring, since the flexibility of the sealing lip in radial direction is still higher than when the sealing lip is positioned in the immediate vicinity of the stiffening ring and vulcanized thereto, the flexibility of the sealing lip in radial direction is however reduced compared to the first embodiment described above.
The outer circumferential surface of the sealing ring can contact the supporting ring.
The stiffening ring and the supporting ring can be respectively separately manufactured and non-positively and/or positively connected with one another.
It is thereby advantageous that the material of the stiffening ring and the material of the supporting ring can be especially well adapted to the respective parameters of the application. For example, it is possible to manufacture the stiffening ring of a metallic material, for example as a deep drawn angled ring, which can be connected simply and cost efficiently, for example by vulcanization, with the elastomeric material of the sealing collar. The supporting ring can consist of a polymeric material, for example of a POM or a PTFE compound and compressed with its axial flange into the stiffening ring.
Such a supporting ring has the advantage that even when the sealing ring is exposed to high pressures and/or large eccentricities and/or out-of round running of the machine element to be sealed, an excellent relative moveability of the sealing collar relative to the supporting ring of friction-reducing material can be maintained. At its axially extending inner surface, the stiffening ring can also be coated with an elastomer. This has the advantage that larger radial tolerances of both the stiffening ring as well as the supporting ring are acceptable and that the rings can be manufactured more cost efficiently.
Furthermore, compared to correspondingly constructed supporting rings of metallic material, supporting rings of polymeric material have a comparatively lower mass, which is advantageous for certain applications.
The construction of the stiffening ring and the supporting ring as two separate parts also allows, for example, the use of rings of complicated shapes which is not possible with a single part.
According to another embodiment, it is possible to construct the stiffening ring and the supporting ring so that they merge together into a single part and are of the same material. It is thereby advantageaus that with such a construction the installation of the sealing ring is simplified, as well as the recycling after exchange of the sealing ring, for example because of regular wear during operation.
The inner axial leg can be radially outwardly surrounded by a garter spring to increase the contact pressure of the sealing lip on the surface of the machine element to be sealed. The garter spring can also be used for compensation of the tension relaxation behavior of elastomers. The use of a garter spring is advantageous especially for the sealing of low pressures in the range of up to 3 bar or for pressure decreases from high pressure to almost ambient pressure, since the small pressure within the space to be sealed is not always sufficient to generate a sealing contact between the sealing lip and the surface of the machine element to be sealed even at high dynamic shaft eccentricity and high shaft rotation speed, and since the garter spring in the case of wear guides the sealing lip upon pressure decrease and forces it against the shaft.
The outer axial leg andlor the radial leg and/or the supporting ring preferably have a friction-reducing surface coating on their mutually opposing surfaces. The surface coating can be achieved, for example, by a PTFE-foil or by a lacquer. Upon exposure of the sealing collar to pressures which are, for example, larger than one bar, the radial leg engages the radial flange of the supporting ring on the side facing away from the space to be sealed and is supported thereby. If the pressure within the space to be sealed increases further, the outer circumferential surface of the radially outer leg, as far as previously radially spaced apart from and adjacent to the axial flange of the supporting ring, engages that axial flange. Due to the friction-reducing surface coating, the sealing collar and the supporting ring are still movable relative to one another, even when pressure changes occur within the space to be sealed, and/or when the sealing collar must compensate for eccentricities and/or out-of round running of the machine element to be sealed. When the supporting ring does not consist of a friction-reducing material, for example, a PTFE
compound or a thermoplastic, but of a metallic material, it is easier with respect to manufacturing technology to apply the friction-reducing surface coating to the supporting ring than onto the elastomeric material of the sealing collar.
The coating of the supporting ring further provides the advantage that surface roughness of the supporting ring has no influence on the adhesion of the sealing collar. For the construction of a surface coating for the sealing collar it is advantageous that, for example, a PTFE foil can be positioned already in the shaping tool for the sealing collar and vulcanized therewith during the shaping process.
The sealing lip can be formed by two mutually intersecting conical surfaces, whereby the first cone angle defined by the first conical surface facing away from the space to be sealed and the axis of the machine element to be sealed is at most 10° less than the second cone angle defined by the second conical surface directed in axial direction towards the space to be sealed and the axis. The two cone angles are essentially about the same. Such a construction is advantageous for the guarantee of a good lubrication of the sealing lip. The wear of the sealing lip during operation is tluereby reduced to a minimum.
It is further advantageous that the length of the inner axial leg is thereby kept short and that the pressing of the sealing collar onto the shaft by the pressure to be sealed can be kept small.
The supporting ring is preferably constructed as an angled ring and has a radial flange and an axial flange which respectively serve as a stop for the radial leg and the radially outer axial leg of the sealing collar.
The first conical surface can have a supporting bead on that side axially facing the radial flange of the supporting ring, whereby the ratio ~f the length of the first conical surface to the length of the second conical surface is 0.3 to 0.8. The supporting bead is sensible especially in connection with a conical surface which defines a relatively large first cone angle with the axis of the machine element to be sealed and/or in connection with pressures to be sealed which exceed 3 bar, for example. Upon exposure of the sealing collar to pressure, the supporting bead engages the side of the supporting surface facing the space to be sealed and thereby prevents the sealing lip flipping over and the second conical surface facing the space to be sealed lying flat on the surface of the machine element to be sealed, thereby significantly negatively influencing the use properties of the sealing ring. The first conical surface, which compared to the second conical surface is shorter and has the supporting bead prevents a flipping over of the sealing lip.
The supporting bead can be made in one-piece with and merging into the sealing collar and made of the same material. By way of this simple design, the sealing ring has a simple construction with few parts and is easily and economically manufactured.
According to another embodiment, the supporting bead can be formed by a separately produced backing ring which is non-positively and/or positively connected with the sealing collar. The backing ring can be made of a PTFE compound, for example. The backing ring is preferably snapped without bonding into an undercut in the first conical surface, which means positively connected therewith. However, it is otherwise also possible to non-positively connect the backing ring with the sealing collar or to bond it thereto. The backing ring prevents an extrusion of the elastomeric material of the sealing lip from the space to be sealed with comparatively higher pressure towards ambient with comparatively lower pressure. The radial height of the backing ring overlaps in radial direction the radially inward end of the radial flange of the supporting ring and is adjacent, except for a small radial spacing, the surface of the machine element to be sealed during the intended use of the sealing ring.
In the manufactured condition of the sealing ring, the sealing lip, when viewed in longitudinal half cross section of the sealing ring, can have an overlap with the surface of the machine element to be sealed which is smaller than the radial spring stroke of the outer axial leg between its outer circumferential surface and a radia.lly outwardly adjacent adjoining axial flange of the supporting ring, which radial spring stroke corresponds to the radial spacing. Such parameters are advantageous in order to always guarantee a spring stroke of the sealing lip in radial direction even in the installed condition of the sealing ring.
The supporting ring can be a component of a housing closure lid. The sealing ring is further simplified by such a construction; on the other hand, the manufacture of the housing closure lid is more difficult with a view to manufacturing technology because of its complicated shape and therefore more expensive.
The supporting ring can be provided with a protecting lip which is positioned on the side of the radial flange axially facing away from the sealing lip, which protecting lip sealingly surrounds the surface of the machine element to be sealed. Such a construction provides the advantage that the protecting lip prevents an intrusion of contaminants from the ambient through the radial gap and towards the sealing lip. The sealing ring can therefore be used without problems even where the surroundings axe highly contaminated.
The invention further relates to a seal arrangement including two of the above-described sealing rings.
Sealing arrangements are generally known. They include a sealing ring with a sealing collar of elastomeric material with at least one sealing lip for the sealing of a space to be sealed, whereby the sealing collar is connected with a supporting ring of tough ductile material, and which, for example, are used as radial shaft sealing rings. The sealing collar and the stiffening ring are thereby vulcanized to one another, whereby the sealing collar is flexible in radial direction in the region of the sealing lip.
Especially in radial shaft sealing rings with an axially short sealing collar for the sealing of pressurized media, a comparatively small flexibility/large stiffness is not satisfactory for many applications, since, for example, eccentricities of the machine element to be sealed and/or use related wear of the sealing lip can only be insufficiently compensated by the sealing ring. For the partial compensation of this constructive defect, the known sealing rings are installed with a relatively large radial overlap, which means the sealing lip when manufactured has a significantly smaller inner diameter than the surface of the machine element to be sealed.
Such a large radial overlap however leads to a high friction moment during operation and to an undesired early wear of the sealing lip.
It is another object of the invention to further develop a sealing arrangement of the above-described type so that it can be used as a double pressure shaft seal and provides improved use properties over an extended period of use. Especially, the friction moment between the sealing collar and the machine element to be sealed is to be reduced.
Eccentricities and/or out-of round running of the machine element to be sealed are to be better compensated by an enlarged range of movement of the sealing lip.
Furthermore, the sealing ring with respect to manufacturing technology and economy should be manufactured simpler and at lower cost. In addition, the sealing arrangement is to be usable for the sealing of higher pressures, for example in the range of up to 200 bar. The sealing collar should thereby be always exactly positioned relative to the other components of the sealing ring and a gap extrusion and the damage/destruction of the material of the sealing collax resulting therefrom is to be prevented.
This object is achieved in accordance with the invention with a sealing arrangement including a first sealing ring with a first sealing collar of elastomeric material, with at least one sealing lip for the sealing of a first space to be sealed, whereby the first sealing collar is connected with a first supporting ring of tough ductile material, whereby the first supporting ring has a first radial flange and a first axial flange, and a second sealing ring with a second sealing collar of elastomeric material with at least a second sealing lip for the sealing of a second space to be sealed which is axially adjacent to the first space, whereby the second sealing collar is connected with a second supporting ring of tough ductile material, whereby the second supporting ring has a second radial flange and a second axial flange and whereby the first sealing ring and the second sealing ring are combined into a pre-assembled unit.
Adjacent pressurized spaces can be reliably sealed from one another with such a construction. The double pressure shaft seal has a simple construction and is therefore manufactured easily and economically. The sealing arrangement can be used, for example, for a bilateral water pump seal, whereby for such a use in the prior art so far two respectively separately produced radial shaft sealing rings are used which are installed in opposite orientation.
The first and second sealing rings can be mirror symmetrically positioned relative to an imaginary radial plane.
The first and second supporting rings can have a common radial flange and can be made in one piece and of the same material. It is thereby advantageous that the number of components of which the sealing arrangement consists is reduced to a minimum.
It is possible, for example, to connect the two supporting rings relatively non-rotatably with one another in the region of their radial flanges, for example, by welding the radial flanges to one another.
According to another embodiment, the two supporting rings can be formed by a single, re-shaped sheet steel part, whereby a single radial flange forms the radial flange for both sealing rings.
According to a preferred embodiment, it is provided that each of the sealing collars, when viewed in longitudinal section of the sealing arrangement, is essentially C-shaped and open axially in the direction of the space to be respectively sealed, having respectively a radially outer and a radially inner axial leg, whereby the axial legs at the end facing axially away from the space to be sealed are respectively connected by a radial leg, the outer axial leg of each sealing collar being connected on the side axially facing the space to be sealed with the free end of the respective axial flange of the corresponding supporting ring and that the respective outer circumferential surface of the respectively outer axial leg and the end surface directed axially away from the space to be sealed of the respective radial leg is associated with the respective supporting ring without bonding.
By way of such a construction, each sealing lip, compared to sealing rings in which the sealing lip is positioned in the immediate vicinity of the stiffening ring and connected thereto by vulcanization, has a comparatively larger range of movement, especially in radial direction; in order to compensate for eccentricities of the machine element to be sealed and/or out-of round running. Furthermore, by way of the unbonded connection of the respectively outer axial leg and the respectively radial leg to the supporting ring and the larger range of movement resulting therefrom, the friction moment between the sealing lip and the machine element to be sealed is reduced, which is of significant advantage with respect to good use properties over a long service period; compared to the afore-described sealing ring from the prior art, the abrasive wear of the sealing lips is significantly reduced. The sealing arrangement in accordance with the invention is especially well suited to seal also higher pressures because of these advantageous use properties. For example, when the sealing arrangement is used as a pump seal, pump pressures of up to 200 bar can be sealed without problem. The very small radial spacing of the radial flanges of the supporting rings from the surface of the machine element to be sealed, whereby the radial width of the radial gaps is 0.01 to 0.2 mm, preferably 0.03 to 0.12 mm, is advantageous in that even when higher pressures are sealed, the material of the sealing collars is not extruded into the radial gaps to an undesired high degree. The sealing arrangement has consistently good use properties over a long service period.
The heat generation is necessarily comparatively small because of the reduced friction moment, as well as the heat transfer to the medium to be sealed, which is, for example, transmission oil or hydraulic oil. The little heat transferred to the medium to be sealed has a positive effect on the aging of the medium to be sealed and/or the decomposition of the additives contained in the medium to be sealed.
According to an especially advantageous embodiment, the respective outer circumferential surface and the respective end surface are spaced apart adjacent to the respective supporting ring and engageable therewith. Such a construction is preferred within the framework of the present invention, since a sealing arrangement constructed in this way solves the above object especially well. Especially the outer circumferential surface which is positioned radially spaced from but adjacent to the axial flange of the supporting ring, whereby the radial spacing forms the radial spring stroke of the sealing lip, causes the advantageous use properties, since by way of the excellent flexibility of the sealing lip in radial direction the friction moment and the heat generation resulting therefrom are significantly reduced and the sealing lip follows very well eccentricities and/or out-of round running of the machine element to be sealed.
According to another embodiment it is possible that the respective outer circumference contacts the respective supporting ring and that only the respective end surface is spaced apart from the respective supporting ring and engageable therewith.
Although a sealing ring of such construction has more advantageous use properties compared to conventional sealing rings, because of the un-bonded association of the outer axial leg with the axial flange of the supporting ring, since the flexibility of the sealing lip in radial direction is nevertheless higher than when the sealing lip is positioned in the immediate vicinity of the stiffening ring and vulcanized thereto, the flexibility of the sealing lip in radial direction is more limited compared to the first embodiment described above.
The respective outer eircumferential surface of the corresponding sealing rings can directly engage the respective supporting ring.
The supporting rings can be made of a polymeric material, fox example, of a PTFE
compound. Such supporting rings have the advantage that even upon exposure of the sealing rings to high pressure and/or large eccentricities and/or out-of round running of the machine element to be sealed, a perfect relative moveability of the sealing collars relative to the respective supporting rings of friction reducing material is maintained.
Supporting rings of polymeric material furthermore have a comparatively smaller mass in comparison to correspondingly constructed supporting rings of metallic materials, which is an advantage for some applications.
The respectively inner axial leg can be surrounded radially outwardly by a garter spring for an increase of the contact pressure of the respective sealing lip with the surface of the machine element to be sealed. Furthermore, the garter spring can be used for compensation of the tension relaxation behaviour of elastomers. Especially for the sealing of lower pressures in the range of up to 3 bar, the use of a garter spring is advantageous, since the small pressure within the space to be sealed is not always sufficient to cause a sealing pressing of the sealing lip onto the surface of the machine element to be sealed at high dynamic shaft eccentricity and high shaft rotation speeds.
The outer axial leg and/or the radial legs and/or the supporting rings can also have a friction-reducing surface coating at the respectively opposite sides. The surface coating can be made, for example, of a PTFE foil or a lacquer.
Upon exposure of the sealing collar to pressures which are, for example, larger than one bar, the radial leg engages the radial flange of the supporting ring on the side facing away from the space to be sealed and is supported thereby. If the pressure within the space to be sealed increases further, the outer circumferential surface of the radially outer leg, as far as previously radially spaced apart from and adjacent to the axial flange of the supporting ring, engages the axial flange. Due to the friction-reducing surface coating, the sealing collar and the supporting ring are still movable relative to one another, even when pressure changes occur within the space to be sealed, and/or when the sealing collar must compensate for eccentricities and/or out-of round running of the machine element to be sealed. When the supporting ring does not consist of a friction-reducing material, for example, a PTFE compound or a thermoplastic, but of a metallic material, it is easier with respect to manufacturing technology to apply the friction-reducing surface coating to the supporting ring than onto the elastomeric material of the sealing collar.
The coating of the supporting ring further provides the advantage that surface roughness of the supporting ring has no influence on the adhesion of the sealing collar. For the construction of a surface coating for the sealing collar it is advantageous that, for example, a PTFE foil can be positioned already in the shaping tool for the sealing collar and vulcanized therewith during the shaping process.
Each of the sealing lips can be formed by two mutually intersecting conical surfaces, whereby the first cone angle defined by the first conical surface facing away from the space to be sealed and the axis of the machine element to be sealed is at most 10°
less than the second cone angle defined by the second conical surface directed in axial direction towards the space to be sealed and the axis. The two cone angles are essentially about the same. Such a construction is advantageous for the guarantee of a good lubrication of the sealing lips. The wear of the sealing lips during operation is thereby reduced to a minimum. It is further advantageous that the length of the inner axial legs is thereby kept short and that the pressing of the sealing collars onto the shaft by the pressure to be sealed can be kept small.
The supporting rings are preferably constructed as an angled ring and respectively have a radial flange and an axial flange. They serve as a stop for the radially outer axial leg of the respective sealing collar.
In the manufactured condition of the respective sealing ring, the respective sealing lip, when viewed in longitudinal half cross section of the sealing ring, can have an overlap with the surface of the machine element to be sealed which is smaller than the radial spring stroke of the respective outer axial leg between its outer circumferential surface and a radially outwardly adjacent adjoining axial flange of the respective supporting ring, which radial spring stroke corresponds to the radial spacing. Such parameters are advantageous in order to always guarantee a spring stroke of the sealing lips in radial direction even in the installed condition of the sealing rings.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail by way of example only and with reference to the attached drawings, wherein Figure 1 illustrates a first preferred embodiment of a seal ring in accordance with the invention;
Figure 2 illustrates a second preferred embodiment of a seal ring in accordance with the invention;
Figure 3 illustrates a third preferred embodiment of a seal ring in accordance with the invention;
Figure 4 illustrates a fourth preferred embodiment of a seal ring in accordance with the invention;
Figure 5 illustrates a fifth preferred embodiment of a seal ring in accordance with the invention;
Figure 6 illustrates a sixth preferred embodiment of a seal ring in accordance with the invention;
Figure 7 illustrates a seventh preferred embodiment of a seal ring in accordance with the invention;
Figure 8 illustrates an eighth preferred embodiment of a seal ring in accordance with the invention;
Figure 9 illustrates a ninth preferred embodiment of a seal ring in accordance with the invention;
Figure 10 illustrates a tenth preferred embodiment of a seal ring in accordance with the invention;
Figure 11 illustrates an eleventh preferred embodiment of a seal ring in accordance with the invention;
Figure 12 illustrates a twelvth preferred embodiment of a seal ring in accordance with the invention;
Figure 13 illustrates a thirteenth preferred embodiment of a seal ring in accordance with the invention;
Figure I4 illustrates a fourteenth preferred embodiment of a seal ring in accordance with the invention;
Figure 15 illustrates a first preferred embodiment of a sealing arrangement in accordance with the invention; and Figure 16 illustrates a second preferred embodiment of a sealing arrangement in accordance with the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figures 1 to 14 respectively show exemplary embodiments of a sealing ring, whereby each of the sealing rings includes a sealing collar 1 of elastomeric material with a sealing lip 2. The sealing rings are shown in the manufactured, un-installed condition, whereby the machine element 15 to be sealed is a shaft shown in broken line illustration.
The sealing of the space to be sealed 3 results from the sealing lip 2 sealingly surrounding the surface 14 of the machine element 15 to be sealed with a radial pretension. A
comparatively higher pressure is present within the space 3 to be sealed compared to ambient 34.
The sealing collar 1 is connected with a stiffening ring 4 consisting of a tough ductile material and in the illustrated exemplary embodiments constructed respectively as a deep drawn angled ring of metallic material.
In Figures 1 to 13, the sealing collar 1, when viewed in longitudinal section of the sealing ring, is essentially C-shaped and open axially in direction to the space 3 to be sealed.
In Figure 14, the sealing collar is not C-shaped.
The sealing collar 1 includes a radially outer axial leg 5 and a radially inner axial leg 6, whereby the two axial legs 5, 6 are connected by the radial leg 7 on that side facing away from the space 3 to be sealed. It is important that the outer axial leg 5 is connected with the stiffening ring 4 only on the side axially facing the space 3 to be sealed and that the outer circurnferential surface 8 of the outer axial leg 5 and the end face 9 of the radial leg 7 axially facing away from the space 3 to be sealed, are respectively associated with the supporting ring 10 without bonding. Only with such a construction is the sealing lip 2 especially flexible in radial direction for the compensation of eccentricities and/or out-of round running of the machine element 15 to be sealed. An excellent bonded association of the sealing collar to the stiffening ring 4 is still present. Furthermore, the friction moment is reduced with such a construction. The heat generation in the region of the sealing lip 2 is thereby limited to a minimum.
The afore-described un-bonded association between the outer circumferential surface 8 of the outer axial leg 5 and the end surface 9 of the radial leg 7 axially facing away from the space 3 to be sealed with the supporting ring 10 is the same in all illustrated exemplary embodiments, whereby sealing rings are shown in Figures 1 and 3 to 13 in which the outer circumferential surface 8 and the end surface 9 are respectively adjacent to the supporting ring 10 and spaced therefrom at a spacing 11, 12.
Tlie spacing shown in Figures 1 to 16 is not to scale belt shown enlarged for better clarity.
The outer circumferential surface 8 and the end surface 9 can engage the supporting ring 10 upon a corresponding pressure within the space to be sealed 3 and/or eccentricities and/or out-of round running of the machine element 15 to be sealed. The supporting ring 10 is with its radial flange 25 positioned very closely to the surface 14 of the machine element 15 to be sealed, so that the radial gap 38 in the illustrated examples has a radial width of only 0.01 to 0.12 mm. Gap extrusion of the elastomeric material of the sealing collar into the radial gap 38 is thereby substantially avoided even when very high pressures in the range of about 200 bar are sealed.
The exemplary embodiment shown in Figure 2 is constructed differently in this respect. The outer circumferential surface 8 directly contacts the supporting ring 10 and only the end surface 9 is spaced at a spacing 12 from the supporting ring 10 and engageable therewith.
In each of the illustrated exemplary embodiments of Figures 1 to 14, the stiffening ring consists of a deep drawn metal material with an axial projection 35 and a radial projection 36, whereby the sealing collar 1 extends around the radial projection 36 and radially outwardly at least partially overlaps the axial projection 35. This provides a static sealing with respect to the installation space of the sealing ring.
The supporting ring 10 is pressed with its axial flange 32 into the axial projection 35 of the stiffening ring 4 and safely held in position thereby. Figure 1 shows a first exemplary embodiment. The supporting ring on its side 18 facing the axial leg
According to another embodiment, the possibility exists that the outer circumferential surface contacts the supporting ring and that only the end surface is positioned spaced apart and adjacent to the supporting ring and engageable therewith.
Although a sealing ring constructed in this way compared to conventional sealing rings has more advantageous use properties because of the un-bonded connection of the outer axial leg to the axial flange of the supporting ring, since the flexibility of the sealing lip in radial direction is still higher than when the sealing lip is positioned in the immediate vicinity of the stiffening ring and vulcanized thereto, the flexibility of the sealing lip in radial direction is however reduced compared to the first embodiment described above.
The outer circumferential surface of the sealing ring can contact the supporting ring.
The stiffening ring and the supporting ring can be respectively separately manufactured and non-positively and/or positively connected with one another.
It is thereby advantageous that the material of the stiffening ring and the material of the supporting ring can be especially well adapted to the respective parameters of the application. For example, it is possible to manufacture the stiffening ring of a metallic material, for example as a deep drawn angled ring, which can be connected simply and cost efficiently, for example by vulcanization, with the elastomeric material of the sealing collar. The supporting ring can consist of a polymeric material, for example of a POM or a PTFE compound and compressed with its axial flange into the stiffening ring.
Such a supporting ring has the advantage that even when the sealing ring is exposed to high pressures and/or large eccentricities and/or out-of round running of the machine element to be sealed, an excellent relative moveability of the sealing collar relative to the supporting ring of friction-reducing material can be maintained. At its axially extending inner surface, the stiffening ring can also be coated with an elastomer. This has the advantage that larger radial tolerances of both the stiffening ring as well as the supporting ring are acceptable and that the rings can be manufactured more cost efficiently.
Furthermore, compared to correspondingly constructed supporting rings of metallic material, supporting rings of polymeric material have a comparatively lower mass, which is advantageous for certain applications.
The construction of the stiffening ring and the supporting ring as two separate parts also allows, for example, the use of rings of complicated shapes which is not possible with a single part.
According to another embodiment, it is possible to construct the stiffening ring and the supporting ring so that they merge together into a single part and are of the same material. It is thereby advantageaus that with such a construction the installation of the sealing ring is simplified, as well as the recycling after exchange of the sealing ring, for example because of regular wear during operation.
The inner axial leg can be radially outwardly surrounded by a garter spring to increase the contact pressure of the sealing lip on the surface of the machine element to be sealed. The garter spring can also be used for compensation of the tension relaxation behavior of elastomers. The use of a garter spring is advantageous especially for the sealing of low pressures in the range of up to 3 bar or for pressure decreases from high pressure to almost ambient pressure, since the small pressure within the space to be sealed is not always sufficient to generate a sealing contact between the sealing lip and the surface of the machine element to be sealed even at high dynamic shaft eccentricity and high shaft rotation speed, and since the garter spring in the case of wear guides the sealing lip upon pressure decrease and forces it against the shaft.
The outer axial leg andlor the radial leg and/or the supporting ring preferably have a friction-reducing surface coating on their mutually opposing surfaces. The surface coating can be achieved, for example, by a PTFE-foil or by a lacquer. Upon exposure of the sealing collar to pressures which are, for example, larger than one bar, the radial leg engages the radial flange of the supporting ring on the side facing away from the space to be sealed and is supported thereby. If the pressure within the space to be sealed increases further, the outer circumferential surface of the radially outer leg, as far as previously radially spaced apart from and adjacent to the axial flange of the supporting ring, engages that axial flange. Due to the friction-reducing surface coating, the sealing collar and the supporting ring are still movable relative to one another, even when pressure changes occur within the space to be sealed, and/or when the sealing collar must compensate for eccentricities and/or out-of round running of the machine element to be sealed. When the supporting ring does not consist of a friction-reducing material, for example, a PTFE
compound or a thermoplastic, but of a metallic material, it is easier with respect to manufacturing technology to apply the friction-reducing surface coating to the supporting ring than onto the elastomeric material of the sealing collar.
The coating of the supporting ring further provides the advantage that surface roughness of the supporting ring has no influence on the adhesion of the sealing collar. For the construction of a surface coating for the sealing collar it is advantageous that, for example, a PTFE foil can be positioned already in the shaping tool for the sealing collar and vulcanized therewith during the shaping process.
The sealing lip can be formed by two mutually intersecting conical surfaces, whereby the first cone angle defined by the first conical surface facing away from the space to be sealed and the axis of the machine element to be sealed is at most 10° less than the second cone angle defined by the second conical surface directed in axial direction towards the space to be sealed and the axis. The two cone angles are essentially about the same. Such a construction is advantageous for the guarantee of a good lubrication of the sealing lip. The wear of the sealing lip during operation is tluereby reduced to a minimum.
It is further advantageous that the length of the inner axial leg is thereby kept short and that the pressing of the sealing collar onto the shaft by the pressure to be sealed can be kept small.
The supporting ring is preferably constructed as an angled ring and has a radial flange and an axial flange which respectively serve as a stop for the radial leg and the radially outer axial leg of the sealing collar.
The first conical surface can have a supporting bead on that side axially facing the radial flange of the supporting ring, whereby the ratio ~f the length of the first conical surface to the length of the second conical surface is 0.3 to 0.8. The supporting bead is sensible especially in connection with a conical surface which defines a relatively large first cone angle with the axis of the machine element to be sealed and/or in connection with pressures to be sealed which exceed 3 bar, for example. Upon exposure of the sealing collar to pressure, the supporting bead engages the side of the supporting surface facing the space to be sealed and thereby prevents the sealing lip flipping over and the second conical surface facing the space to be sealed lying flat on the surface of the machine element to be sealed, thereby significantly negatively influencing the use properties of the sealing ring. The first conical surface, which compared to the second conical surface is shorter and has the supporting bead prevents a flipping over of the sealing lip.
The supporting bead can be made in one-piece with and merging into the sealing collar and made of the same material. By way of this simple design, the sealing ring has a simple construction with few parts and is easily and economically manufactured.
According to another embodiment, the supporting bead can be formed by a separately produced backing ring which is non-positively and/or positively connected with the sealing collar. The backing ring can be made of a PTFE compound, for example. The backing ring is preferably snapped without bonding into an undercut in the first conical surface, which means positively connected therewith. However, it is otherwise also possible to non-positively connect the backing ring with the sealing collar or to bond it thereto. The backing ring prevents an extrusion of the elastomeric material of the sealing lip from the space to be sealed with comparatively higher pressure towards ambient with comparatively lower pressure. The radial height of the backing ring overlaps in radial direction the radially inward end of the radial flange of the supporting ring and is adjacent, except for a small radial spacing, the surface of the machine element to be sealed during the intended use of the sealing ring.
In the manufactured condition of the sealing ring, the sealing lip, when viewed in longitudinal half cross section of the sealing ring, can have an overlap with the surface of the machine element to be sealed which is smaller than the radial spring stroke of the outer axial leg between its outer circumferential surface and a radia.lly outwardly adjacent adjoining axial flange of the supporting ring, which radial spring stroke corresponds to the radial spacing. Such parameters are advantageous in order to always guarantee a spring stroke of the sealing lip in radial direction even in the installed condition of the sealing ring.
The supporting ring can be a component of a housing closure lid. The sealing ring is further simplified by such a construction; on the other hand, the manufacture of the housing closure lid is more difficult with a view to manufacturing technology because of its complicated shape and therefore more expensive.
The supporting ring can be provided with a protecting lip which is positioned on the side of the radial flange axially facing away from the sealing lip, which protecting lip sealingly surrounds the surface of the machine element to be sealed. Such a construction provides the advantage that the protecting lip prevents an intrusion of contaminants from the ambient through the radial gap and towards the sealing lip. The sealing ring can therefore be used without problems even where the surroundings axe highly contaminated.
The invention further relates to a seal arrangement including two of the above-described sealing rings.
Sealing arrangements are generally known. They include a sealing ring with a sealing collar of elastomeric material with at least one sealing lip for the sealing of a space to be sealed, whereby the sealing collar is connected with a supporting ring of tough ductile material, and which, for example, are used as radial shaft sealing rings. The sealing collar and the stiffening ring are thereby vulcanized to one another, whereby the sealing collar is flexible in radial direction in the region of the sealing lip.
Especially in radial shaft sealing rings with an axially short sealing collar for the sealing of pressurized media, a comparatively small flexibility/large stiffness is not satisfactory for many applications, since, for example, eccentricities of the machine element to be sealed and/or use related wear of the sealing lip can only be insufficiently compensated by the sealing ring. For the partial compensation of this constructive defect, the known sealing rings are installed with a relatively large radial overlap, which means the sealing lip when manufactured has a significantly smaller inner diameter than the surface of the machine element to be sealed.
Such a large radial overlap however leads to a high friction moment during operation and to an undesired early wear of the sealing lip.
It is another object of the invention to further develop a sealing arrangement of the above-described type so that it can be used as a double pressure shaft seal and provides improved use properties over an extended period of use. Especially, the friction moment between the sealing collar and the machine element to be sealed is to be reduced.
Eccentricities and/or out-of round running of the machine element to be sealed are to be better compensated by an enlarged range of movement of the sealing lip.
Furthermore, the sealing ring with respect to manufacturing technology and economy should be manufactured simpler and at lower cost. In addition, the sealing arrangement is to be usable for the sealing of higher pressures, for example in the range of up to 200 bar. The sealing collar should thereby be always exactly positioned relative to the other components of the sealing ring and a gap extrusion and the damage/destruction of the material of the sealing collax resulting therefrom is to be prevented.
This object is achieved in accordance with the invention with a sealing arrangement including a first sealing ring with a first sealing collar of elastomeric material, with at least one sealing lip for the sealing of a first space to be sealed, whereby the first sealing collar is connected with a first supporting ring of tough ductile material, whereby the first supporting ring has a first radial flange and a first axial flange, and a second sealing ring with a second sealing collar of elastomeric material with at least a second sealing lip for the sealing of a second space to be sealed which is axially adjacent to the first space, whereby the second sealing collar is connected with a second supporting ring of tough ductile material, whereby the second supporting ring has a second radial flange and a second axial flange and whereby the first sealing ring and the second sealing ring are combined into a pre-assembled unit.
Adjacent pressurized spaces can be reliably sealed from one another with such a construction. The double pressure shaft seal has a simple construction and is therefore manufactured easily and economically. The sealing arrangement can be used, for example, for a bilateral water pump seal, whereby for such a use in the prior art so far two respectively separately produced radial shaft sealing rings are used which are installed in opposite orientation.
The first and second sealing rings can be mirror symmetrically positioned relative to an imaginary radial plane.
The first and second supporting rings can have a common radial flange and can be made in one piece and of the same material. It is thereby advantageous that the number of components of which the sealing arrangement consists is reduced to a minimum.
It is possible, for example, to connect the two supporting rings relatively non-rotatably with one another in the region of their radial flanges, for example, by welding the radial flanges to one another.
According to another embodiment, the two supporting rings can be formed by a single, re-shaped sheet steel part, whereby a single radial flange forms the radial flange for both sealing rings.
According to a preferred embodiment, it is provided that each of the sealing collars, when viewed in longitudinal section of the sealing arrangement, is essentially C-shaped and open axially in the direction of the space to be respectively sealed, having respectively a radially outer and a radially inner axial leg, whereby the axial legs at the end facing axially away from the space to be sealed are respectively connected by a radial leg, the outer axial leg of each sealing collar being connected on the side axially facing the space to be sealed with the free end of the respective axial flange of the corresponding supporting ring and that the respective outer circumferential surface of the respectively outer axial leg and the end surface directed axially away from the space to be sealed of the respective radial leg is associated with the respective supporting ring without bonding.
By way of such a construction, each sealing lip, compared to sealing rings in which the sealing lip is positioned in the immediate vicinity of the stiffening ring and connected thereto by vulcanization, has a comparatively larger range of movement, especially in radial direction; in order to compensate for eccentricities of the machine element to be sealed and/or out-of round running. Furthermore, by way of the unbonded connection of the respectively outer axial leg and the respectively radial leg to the supporting ring and the larger range of movement resulting therefrom, the friction moment between the sealing lip and the machine element to be sealed is reduced, which is of significant advantage with respect to good use properties over a long service period; compared to the afore-described sealing ring from the prior art, the abrasive wear of the sealing lips is significantly reduced. The sealing arrangement in accordance with the invention is especially well suited to seal also higher pressures because of these advantageous use properties. For example, when the sealing arrangement is used as a pump seal, pump pressures of up to 200 bar can be sealed without problem. The very small radial spacing of the radial flanges of the supporting rings from the surface of the machine element to be sealed, whereby the radial width of the radial gaps is 0.01 to 0.2 mm, preferably 0.03 to 0.12 mm, is advantageous in that even when higher pressures are sealed, the material of the sealing collars is not extruded into the radial gaps to an undesired high degree. The sealing arrangement has consistently good use properties over a long service period.
The heat generation is necessarily comparatively small because of the reduced friction moment, as well as the heat transfer to the medium to be sealed, which is, for example, transmission oil or hydraulic oil. The little heat transferred to the medium to be sealed has a positive effect on the aging of the medium to be sealed and/or the decomposition of the additives contained in the medium to be sealed.
According to an especially advantageous embodiment, the respective outer circumferential surface and the respective end surface are spaced apart adjacent to the respective supporting ring and engageable therewith. Such a construction is preferred within the framework of the present invention, since a sealing arrangement constructed in this way solves the above object especially well. Especially the outer circumferential surface which is positioned radially spaced from but adjacent to the axial flange of the supporting ring, whereby the radial spacing forms the radial spring stroke of the sealing lip, causes the advantageous use properties, since by way of the excellent flexibility of the sealing lip in radial direction the friction moment and the heat generation resulting therefrom are significantly reduced and the sealing lip follows very well eccentricities and/or out-of round running of the machine element to be sealed.
According to another embodiment it is possible that the respective outer circumference contacts the respective supporting ring and that only the respective end surface is spaced apart from the respective supporting ring and engageable therewith.
Although a sealing ring of such construction has more advantageous use properties compared to conventional sealing rings, because of the un-bonded association of the outer axial leg with the axial flange of the supporting ring, since the flexibility of the sealing lip in radial direction is nevertheless higher than when the sealing lip is positioned in the immediate vicinity of the stiffening ring and vulcanized thereto, the flexibility of the sealing lip in radial direction is more limited compared to the first embodiment described above.
The respective outer eircumferential surface of the corresponding sealing rings can directly engage the respective supporting ring.
The supporting rings can be made of a polymeric material, fox example, of a PTFE
compound. Such supporting rings have the advantage that even upon exposure of the sealing rings to high pressure and/or large eccentricities and/or out-of round running of the machine element to be sealed, a perfect relative moveability of the sealing collars relative to the respective supporting rings of friction reducing material is maintained.
Supporting rings of polymeric material furthermore have a comparatively smaller mass in comparison to correspondingly constructed supporting rings of metallic materials, which is an advantage for some applications.
The respectively inner axial leg can be surrounded radially outwardly by a garter spring for an increase of the contact pressure of the respective sealing lip with the surface of the machine element to be sealed. Furthermore, the garter spring can be used for compensation of the tension relaxation behaviour of elastomers. Especially for the sealing of lower pressures in the range of up to 3 bar, the use of a garter spring is advantageous, since the small pressure within the space to be sealed is not always sufficient to cause a sealing pressing of the sealing lip onto the surface of the machine element to be sealed at high dynamic shaft eccentricity and high shaft rotation speeds.
The outer axial leg and/or the radial legs and/or the supporting rings can also have a friction-reducing surface coating at the respectively opposite sides. The surface coating can be made, for example, of a PTFE foil or a lacquer.
Upon exposure of the sealing collar to pressures which are, for example, larger than one bar, the radial leg engages the radial flange of the supporting ring on the side facing away from the space to be sealed and is supported thereby. If the pressure within the space to be sealed increases further, the outer circumferential surface of the radially outer leg, as far as previously radially spaced apart from and adjacent to the axial flange of the supporting ring, engages the axial flange. Due to the friction-reducing surface coating, the sealing collar and the supporting ring are still movable relative to one another, even when pressure changes occur within the space to be sealed, and/or when the sealing collar must compensate for eccentricities and/or out-of round running of the machine element to be sealed. When the supporting ring does not consist of a friction-reducing material, for example, a PTFE compound or a thermoplastic, but of a metallic material, it is easier with respect to manufacturing technology to apply the friction-reducing surface coating to the supporting ring than onto the elastomeric material of the sealing collar.
The coating of the supporting ring further provides the advantage that surface roughness of the supporting ring has no influence on the adhesion of the sealing collar. For the construction of a surface coating for the sealing collar it is advantageous that, for example, a PTFE foil can be positioned already in the shaping tool for the sealing collar and vulcanized therewith during the shaping process.
Each of the sealing lips can be formed by two mutually intersecting conical surfaces, whereby the first cone angle defined by the first conical surface facing away from the space to be sealed and the axis of the machine element to be sealed is at most 10°
less than the second cone angle defined by the second conical surface directed in axial direction towards the space to be sealed and the axis. The two cone angles are essentially about the same. Such a construction is advantageous for the guarantee of a good lubrication of the sealing lips. The wear of the sealing lips during operation is thereby reduced to a minimum. It is further advantageous that the length of the inner axial legs is thereby kept short and that the pressing of the sealing collars onto the shaft by the pressure to be sealed can be kept small.
The supporting rings are preferably constructed as an angled ring and respectively have a radial flange and an axial flange. They serve as a stop for the radially outer axial leg of the respective sealing collar.
In the manufactured condition of the respective sealing ring, the respective sealing lip, when viewed in longitudinal half cross section of the sealing ring, can have an overlap with the surface of the machine element to be sealed which is smaller than the radial spring stroke of the respective outer axial leg between its outer circumferential surface and a radially outwardly adjacent adjoining axial flange of the respective supporting ring, which radial spring stroke corresponds to the radial spacing. Such parameters are advantageous in order to always guarantee a spring stroke of the sealing lips in radial direction even in the installed condition of the sealing rings.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail by way of example only and with reference to the attached drawings, wherein Figure 1 illustrates a first preferred embodiment of a seal ring in accordance with the invention;
Figure 2 illustrates a second preferred embodiment of a seal ring in accordance with the invention;
Figure 3 illustrates a third preferred embodiment of a seal ring in accordance with the invention;
Figure 4 illustrates a fourth preferred embodiment of a seal ring in accordance with the invention;
Figure 5 illustrates a fifth preferred embodiment of a seal ring in accordance with the invention;
Figure 6 illustrates a sixth preferred embodiment of a seal ring in accordance with the invention;
Figure 7 illustrates a seventh preferred embodiment of a seal ring in accordance with the invention;
Figure 8 illustrates an eighth preferred embodiment of a seal ring in accordance with the invention;
Figure 9 illustrates a ninth preferred embodiment of a seal ring in accordance with the invention;
Figure 10 illustrates a tenth preferred embodiment of a seal ring in accordance with the invention;
Figure 11 illustrates an eleventh preferred embodiment of a seal ring in accordance with the invention;
Figure 12 illustrates a twelvth preferred embodiment of a seal ring in accordance with the invention;
Figure 13 illustrates a thirteenth preferred embodiment of a seal ring in accordance with the invention;
Figure I4 illustrates a fourteenth preferred embodiment of a seal ring in accordance with the invention;
Figure 15 illustrates a first preferred embodiment of a sealing arrangement in accordance with the invention; and Figure 16 illustrates a second preferred embodiment of a sealing arrangement in accordance with the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figures 1 to 14 respectively show exemplary embodiments of a sealing ring, whereby each of the sealing rings includes a sealing collar 1 of elastomeric material with a sealing lip 2. The sealing rings are shown in the manufactured, un-installed condition, whereby the machine element 15 to be sealed is a shaft shown in broken line illustration.
The sealing of the space to be sealed 3 results from the sealing lip 2 sealingly surrounding the surface 14 of the machine element 15 to be sealed with a radial pretension. A
comparatively higher pressure is present within the space 3 to be sealed compared to ambient 34.
The sealing collar 1 is connected with a stiffening ring 4 consisting of a tough ductile material and in the illustrated exemplary embodiments constructed respectively as a deep drawn angled ring of metallic material.
In Figures 1 to 13, the sealing collar 1, when viewed in longitudinal section of the sealing ring, is essentially C-shaped and open axially in direction to the space 3 to be sealed.
In Figure 14, the sealing collar is not C-shaped.
The sealing collar 1 includes a radially outer axial leg 5 and a radially inner axial leg 6, whereby the two axial legs 5, 6 are connected by the radial leg 7 on that side facing away from the space 3 to be sealed. It is important that the outer axial leg 5 is connected with the stiffening ring 4 only on the side axially facing the space 3 to be sealed and that the outer circurnferential surface 8 of the outer axial leg 5 and the end face 9 of the radial leg 7 axially facing away from the space 3 to be sealed, are respectively associated with the supporting ring 10 without bonding. Only with such a construction is the sealing lip 2 especially flexible in radial direction for the compensation of eccentricities and/or out-of round running of the machine element 15 to be sealed. An excellent bonded association of the sealing collar to the stiffening ring 4 is still present. Furthermore, the friction moment is reduced with such a construction. The heat generation in the region of the sealing lip 2 is thereby limited to a minimum.
The afore-described un-bonded association between the outer circumferential surface 8 of the outer axial leg 5 and the end surface 9 of the radial leg 7 axially facing away from the space 3 to be sealed with the supporting ring 10 is the same in all illustrated exemplary embodiments, whereby sealing rings are shown in Figures 1 and 3 to 13 in which the outer circumferential surface 8 and the end surface 9 are respectively adjacent to the supporting ring 10 and spaced therefrom at a spacing 11, 12.
Tlie spacing shown in Figures 1 to 16 is not to scale belt shown enlarged for better clarity.
The outer circumferential surface 8 and the end surface 9 can engage the supporting ring 10 upon a corresponding pressure within the space to be sealed 3 and/or eccentricities and/or out-of round running of the machine element 15 to be sealed. The supporting ring 10 is with its radial flange 25 positioned very closely to the surface 14 of the machine element 15 to be sealed, so that the radial gap 38 in the illustrated examples has a radial width of only 0.01 to 0.12 mm. Gap extrusion of the elastomeric material of the sealing collar into the radial gap 38 is thereby substantially avoided even when very high pressures in the range of about 200 bar are sealed.
The exemplary embodiment shown in Figure 2 is constructed differently in this respect. The outer circumferential surface 8 directly contacts the supporting ring 10 and only the end surface 9 is spaced at a spacing 12 from the supporting ring 10 and engageable therewith.
In each of the illustrated exemplary embodiments of Figures 1 to 14, the stiffening ring consists of a deep drawn metal material with an axial projection 35 and a radial projection 36, whereby the sealing collar 1 extends around the radial projection 36 and radially outwardly at least partially overlaps the axial projection 35. This provides a static sealing with respect to the installation space of the sealing ring.
The supporting ring 10 is pressed with its axial flange 32 into the axial projection 35 of the stiffening ring 4 and safely held in position thereby. Figure 1 shows a first exemplary embodiment. The supporting ring on its side 18 facing the axial leg
5 and the radial leg 7 of the sealing collar 1 are provided with a surface coating 19 which is formed by a PTFE foil. The surface coating 19 prevents a sticking of the elastomeric material of the sealing collar 1 upon pressure release so that the sealing lip 2 can elastically move about its joint-like connection with the radial projection 36.
In Figure l, the supporting ring 10 is connected with a protection lip 42 positioned on the side of the radial flange 25 axially facing away from the sealing lip 2 and sealingly surrounding the surface 14 of the machine element 15 to be sealed. Such a protecting lip 42, which is connected with the supporting ring in this way can also be used in the remaining exemplary embodiments illustrated here. The proj ecting lip 42 prevents the intrusion of contaminants from ambient 34 through the radial gap 38 in the direction of the sealing lip 2. The sealing ring in accordance with the invention/the sealing arrangement in accordance with the invention can therefore be used even when the ambient is highly contaminated. Even under those operating conditions, the claimed sealing ringsJsealing arrangement of the invention has continuously good use properties over a long service period.
Figure 2 shows a second exemplary embodiment of the sealing ring which is distinguished from the other exemplary embodiments in that the outer circumferential surface 8 directly engages the supporting ring. The radial leg 7 is spaced apart adjacent to the radial flange 25 on the side facing the space 3 to be sealed. Upon pressurization, the radial leg 7 is supported on the radial flange 25.
Figure 3 shows a third exemplary embodiment, wherein a supporting ring 10 of polymeric material is used: The supporting ring 10 consists of a low friction polyamide and can be manufactured by injection molding. Potentially needed, complicated geometries can be realized by using the polymeric material as the material for the supporting ring 10. The application of a separately produced, friction reducing surface coating is obviated by making the supporting ring 10 of the low friction polyamide.
Figure 4 shows a fourth exemplary embodiment of a seal ring in accordance with the invention, wherein the stiffening ring 4 and the supporting ring 10 are merged together into a single part and made of the same material. Furthermore, an additional supporting ring 37 is provided on that side facing the space to be sealed 3, for the purpose of preventing a flipping over of the sealing lip 2 under excessive pressure and upon improper installation. Improper installation in this context refers in this exemplary embodiment to insertion of the machine part 1 S to be sealed into the seal ring from the left; the correct installation should be carried out from the right as in the other embodiments.
Figure 5 shows an exemplary embodiment similar to that of Figure 3, wherein the supporting ring 10 is made of a metallic material.
Figure 6 illustrates a sixth exemplary embodiment of a seal ring in accordance with the invention. A supporting bead 26 in the shape of a backing ring 29 is provided on that side of the sealing lip 2 facing away from the space to be sealed 3, which bead prevents an extrusion of the elastomeric material of which the sealing lip 2 is made into the sealing gap upon elevated pressures in the space to be sealed. The backing ring 29 has the additional purpose to protect the seal from wear and to prevent a flipping over of the sealing lip 2, such that the second conical surface 2 i facing the space to be sealed 3 comes to rest on the surface 14 of the machine element 15 to be sealed.
Figure 7 shows a seventh exemplary embodiment of the seal ring. The radial spacing 11 between the outer circumferential surface 8 of the radially outer axial leg 5 and the axial flange 32 of the supporting ring 10, when viewed in axial direction, is constant.
Such an embodiment is advantageous in that the tools required far the manufacture of the sealing ring are easily manufactured and, thus, cost efficient.
Figure 8 illustrates an eighth exemplary embodiment of the seal ring. Contrary to the embodiment of Figure 7, the radial spacing 11 is not even along the axial extent of the radially outer axial leg S, but, as in almost all remaining embodiments, continuously decreases in axial direction when viewed from the radial leg 7 in direction of the radial projection 36. Starting at the radial projection 36, the outer cirumferential surface 8, when viewed in axial direction, gradually comes to rest against the axial flange 32 of the supporting ring 10. Localized tension is thereby avoided.
In this exemplary embodiment, the sides 16, 17 of the radially outer leg 5 and the radial leg 7 are provided with a unitary, merged friction reducing surface coating which is made of a PTFE foil.
The radial flange 25 on its side facing the surface 14 of the machine element to be sealed 15 has a supporting projection 39 which extends under the sealing lip 2 and projects axially in direction of the space to be sealed. Undesirably large shape changes of the sealing collar 1 during the intended use are prevented in that the sealing collar 1 is supported in the region of its sealing lip 2 by the supporting projection 39.
Figures 9 and 10 respectively show an exemplary embodiment which essentially corresponds to the one of Figure 6, whereby the backing rings 29 used as the supporting bead 26 are of different construction.
In Figure 9, the backing ring 29 is rectangular and prevents an extruding of the sealing lip 2 into the seal gap as well as a flipping over of the sealing lip 2 towards the ambient 34. The rectangular geometry of the backing ring 29 can be cost efficiently and reliably manufactured.
In Figure 10, the backing ring 29 is wedge shaped and also consists of a polymeric material, which provides good wear and strength properties. Even at low operating pressures, the backing ring 29 radially spaced apart surrounds the surface 14 of the machine element to be sealed 15, whereby the total friction moment is very small as well as the friction heat generated. At higher system pressures within the space to be sealed, this backing ring 29 also prevents the extrusion of the elastomeric material of the sealing collar 1 towards ambient.
Figure 11 shows an eleventh exemplary embodiment, wherein the supporting ring forms part of a housing cover 3.3.
Figure 12 shows an exemplary embodiment of a sealing ring similar to the afore-described exemplary embodiments, whereby however no garter spring 13 is used.
This variant has the advantage that the seal generates smaller friction during pressure free operation, since the initial contact force is generated only by the overlapping of the sealing lip 2 with the surface 14 of the machine element to be sealed 15. Overall, the sealing lip thereby exhibits less wear and improved efficiency.
In all illustrated exemplary embodiments, the first and second cone angles 22, appear to be of the same size. The sealing lip 2 is formed in each of the exemplary embodiments by two mutually intersecting conical surfaces 20, 21, whereby the first cone angle 22 defined by the axis 24 of the machine element to be sealed 15 and the first conical surface 20 facing away from the space to be sealed is at most 10%
smaller than the second cone angle 23 defined by the axis 24 and the second conical surface 21 facing the space to be sealed 3.
By positioning the supporting bead 26 partially as a backing ring 29, the ratio of the length 27 of the first conical surface 20 to the length 28 of the second conical surface 21 is 0.3 to 0.8 in the illustrated exemplary embodiments.
Figure 13 shows an exemplary embodiment wherein the axial projection 35 is coated on its inner side with an elastomer 37. This is advantageous in that larger radial tolerances of both the stiffening ring 4 as well as the supporting ring 10 are without negative effect, whereby the rings 4,10 can be more cost effectively manufactured. As in the embodiment of Figure 8, the radial flange 25 of the supporting ring 10 is provided on its side facing the surface 14 of the machine element to be sealed 15 with a supporting projection 39 which projects axially in direction of the space to be sealed 3 and extends under the sealing lip 2.
Figure 14 shows a further exemplary embodiment, which is distinguished from the ones described before in that the sealing collar 1 is not C-shaped.
Furthermore, the supporting ring 10 extends radially outwardly and can center itself in the aggregate to be sealed.
In the exemplary embodiments shown, the sealing lip 2 in the manufactured condition of the sealing ring as seen in longitudinal section of the sealing ring has an overlap 30 with the surface 14 of the machine element to be sealed 15, which overlap is smaller than the radial spring stroke 31 of the outer axial leg 5 corresponding to the radial spacing 11 between the outer circumferential surface 8 of the axial leg 5 and the radially outwardly adjacent axial flange 32 of the supporting ring 10. This holds true for all exemplary embodiments, except for the exemplary embodiment of Figure 2, wherein no radial spring stroke is provided. By way of the described relationship between the overlap and the radial spacing 11/the corresponding spring stroke 31, it is ensured that a radial spring stroke is maintained even when the sealing ring is mounted on the machine element to be sealed.
Figures 15 and 16 each illustrate an exemplary embodiment of a seal arrangement in accordance with the invention, whereby each of the sealing arrangements includes two sealing collars l .l, 1.2 of elastomeric material and whereby each of the sealing collars 1. l, 1.2 includes a sealing lip 2.1, 2.2. The sealing arrangements are shown in the manufactured, un-installed condition, wherein the machine element to be sealed 15 is in the form of a shaft and shown in broken lines. The sealing of the spaces to be sealed 3.1, 3.2 is achieved in that the sealing lips 2.1, 2.2 sealingly engage the machine element to be sealed 15 under radial tension. The pressure in the spaces to be sealed 3.1, 3.2 is comparatively higher than ambient pressure.
Each of the sealing collars 1.1, 1.2 is provided with a supporting ring 10.1, 10.2 of tough ductile material, which ring in the illustrated exemplary embodiments is constructed as a deep-drawn angled ring made of metallic material.
The sealing collars 1.1, 1.2, when viewed in longitudinal section of the sealing arrangement, are essentially C-shaped and open in axial direction towards the respective space to be sealed 3.1, 3.2. The first supporting ring 10.1 is provided with a first radial leg 25.1 and a first axial flange 32.1, the second supporting ring 10.2 with a second radial leg 25.2 and a second axial flange 32.2. Both sealing rings are combined to a pre-assembled unit 40.
For the sealing of axially adjacent spaces 3.1, 3.2 the two sealing rings are positioned mirror symmetrical to an imaginary radial plane 41. According to the embodiment of Figure 1, both radial flanges 25.1, 25.2 are relatively non-rotatably connected with one another, in this exemplary embodiment by spot welding. In contrast, the first and second supporting rings 10.1 and 10.2 shown in Figure 2 are formed as one unit and of the same material and therefore have a common radial flange 25.
Each of the sealing collars 1.1, 1.2 respectively has a radially outer axial leg 5.1, 5.2 and a radially inner axial leg 6.1, 6.2, whereby the axial legs 6.1, 6.2 are connected by a respective radial leg 7.1, 7.2 on their side axially facing away from the space to be sealed 3.1, 3.2. The outer axial leg 5.1, 5.2 of each sealing collar 1.1, 1.2 is only on the side axially facing the space to be sealed 3.1, 3.2 connected with the free end of the respective axial flange 32.1, 32.2 of the corresponding supporting ring 10.1, 10.2. The respective outer circumferential surface 8.1, 8.2 of the respective outer axial leg 5.1, 5.2 and the end faces 9.1, 9.2 of the respective radial flange 7.1, 7.2 axially facing away from the respective space to be sealed 3.1, 3.2 are un-bonded to the respective supporting ring 10.1, 10.2. Only with such a construction are the sealing lips 2.1, 2.2 especially flexible in radial direction in order to balance eccentricities or out-of round running of the machine element to be sealed. The supporting rings 10.1, 10,2 are closely adjacent with their radial flanges 25, 25.1, 25.2 to the surface 14 of the machine element to be sealed 15, so that the radial gap 38, 38.1, 38.2 in the illustrated examples has only a width of 0.03 to 0.08 mm. Gap extrusion of the elastomeric material of the sealing collar into the radial gaps 38, 38.1, 38.2 is thereby substantially prevented even during the sealing of very high pressures in the range of about 200 bar.
Furthermore, the friction moment is reduced with such a construction. The heat generation in the region of the two sealing lips 2.1, 2.2 is thereby reduced to a minimum.
The afore-described un-bonded association of the outer circumferential surfaces 8.1, 8.2 of the respective outer axial leg 5.1, 5.2 and of the end faces 9.1, 9.2 of the radial legs 7.1, 7.2 respectively facing away from the space to be sealed 3.1, 3.2, with the respective supporting rings 10. l, 10.2 is the same in the embodiments illustrated here. The outer circumferential surfaces 8.1, 8.2 and the end faces 9.1, 9.2 are positioned at a spacing 1 l.l, 11.2, 12.1, 12.2 to the respective supporting rings 10.1, 10.2.
Upon a corresponding elevated pressure within the spaces to be sealed 3.1, 3.2 and/or upon eccentricities and/or upon an out-of round running of the machine element to be sealed 15, the outer circumferential surfaces 8.1, 8.2 and the end faces 9.1, 9.2 can engage the respective supporting rings 10.1, 10.2.
In the illustrated exemplary embodiments, the respectively first cone angle 22.1, 22.2 and the respectively second cone angle 23. l, 23.2 appear to be of the same size. The sealing lips 2. l, 2.2 are formed in each of the exemplary embodiments respectively by two mutually intersecting conical surfaces 20.1, 21.1, 20.2, 21.2, whereby the first cone angle 22.1, 22.2 defined by the axis 24 of the machine element to be sealed 15 and the first conical surface 20.1, 20.2 facing away from the space to be sealed 3.1, 3.2 is at most 10%
smaller than the second cone angle 23.1, 23.2 defined by the axis 24 and the second conical surface 21.1, 21.2 facing the space to be sealed 3.1, 3.2.
In the exemplary embodiments shown, the sealing lips 2.1, 2.2 in the manufactured condition of the sealing ring as seen in longitudinal section of the sealing ring have an overlap 30 with the surface 14 of the machine element to be sealed 15, which overlap is smaller than the radial spring stroke 31.1, 31.2 of the respective outer axial leg 5.1, 5.2 corresponding to the radial spacing 1 l.l, 11.2 between the respective outer circumferential surface 8.1, 8.2 of the axial leg 5.1, 5.2 and the radially outwardly adjacent axial flange 32.1, 32.2 of the supporting ring 10.1, 10.2. By way of the relationship between the overlap 30.1, 30.2 and the radial spacing 11.1, 11.2/the corresponding spring stroke 31.1, 31.2, it is ensured that a radial spring stroke 31.1, 31.2 is maintained even when the sealing ring is mounted on the machine element to be sealed.
In the embodiment of Figure 15, the first supporting ring 10.1 is provided with a supporting projection 39 which protects the inner axial leg 6.1 from undesired high mechanical loads, even under very high pressure, for example in the range of 200 bar, which can be present in the space to be sealed 3.1.
A unitary construction of stiffening ring and supporting ring is shown in Figure 1 ~.
In Figure l, the supporting ring 10 is connected with a protection lip 42 positioned on the side of the radial flange 25 axially facing away from the sealing lip 2 and sealingly surrounding the surface 14 of the machine element 15 to be sealed. Such a protecting lip 42, which is connected with the supporting ring in this way can also be used in the remaining exemplary embodiments illustrated here. The proj ecting lip 42 prevents the intrusion of contaminants from ambient 34 through the radial gap 38 in the direction of the sealing lip 2. The sealing ring in accordance with the invention/the sealing arrangement in accordance with the invention can therefore be used even when the ambient is highly contaminated. Even under those operating conditions, the claimed sealing ringsJsealing arrangement of the invention has continuously good use properties over a long service period.
Figure 2 shows a second exemplary embodiment of the sealing ring which is distinguished from the other exemplary embodiments in that the outer circumferential surface 8 directly engages the supporting ring. The radial leg 7 is spaced apart adjacent to the radial flange 25 on the side facing the space 3 to be sealed. Upon pressurization, the radial leg 7 is supported on the radial flange 25.
Figure 3 shows a third exemplary embodiment, wherein a supporting ring 10 of polymeric material is used: The supporting ring 10 consists of a low friction polyamide and can be manufactured by injection molding. Potentially needed, complicated geometries can be realized by using the polymeric material as the material for the supporting ring 10. The application of a separately produced, friction reducing surface coating is obviated by making the supporting ring 10 of the low friction polyamide.
Figure 4 shows a fourth exemplary embodiment of a seal ring in accordance with the invention, wherein the stiffening ring 4 and the supporting ring 10 are merged together into a single part and made of the same material. Furthermore, an additional supporting ring 37 is provided on that side facing the space to be sealed 3, for the purpose of preventing a flipping over of the sealing lip 2 under excessive pressure and upon improper installation. Improper installation in this context refers in this exemplary embodiment to insertion of the machine part 1 S to be sealed into the seal ring from the left; the correct installation should be carried out from the right as in the other embodiments.
Figure 5 shows an exemplary embodiment similar to that of Figure 3, wherein the supporting ring 10 is made of a metallic material.
Figure 6 illustrates a sixth exemplary embodiment of a seal ring in accordance with the invention. A supporting bead 26 in the shape of a backing ring 29 is provided on that side of the sealing lip 2 facing away from the space to be sealed 3, which bead prevents an extrusion of the elastomeric material of which the sealing lip 2 is made into the sealing gap upon elevated pressures in the space to be sealed. The backing ring 29 has the additional purpose to protect the seal from wear and to prevent a flipping over of the sealing lip 2, such that the second conical surface 2 i facing the space to be sealed 3 comes to rest on the surface 14 of the machine element 15 to be sealed.
Figure 7 shows a seventh exemplary embodiment of the seal ring. The radial spacing 11 between the outer circumferential surface 8 of the radially outer axial leg 5 and the axial flange 32 of the supporting ring 10, when viewed in axial direction, is constant.
Such an embodiment is advantageous in that the tools required far the manufacture of the sealing ring are easily manufactured and, thus, cost efficient.
Figure 8 illustrates an eighth exemplary embodiment of the seal ring. Contrary to the embodiment of Figure 7, the radial spacing 11 is not even along the axial extent of the radially outer axial leg S, but, as in almost all remaining embodiments, continuously decreases in axial direction when viewed from the radial leg 7 in direction of the radial projection 36. Starting at the radial projection 36, the outer cirumferential surface 8, when viewed in axial direction, gradually comes to rest against the axial flange 32 of the supporting ring 10. Localized tension is thereby avoided.
In this exemplary embodiment, the sides 16, 17 of the radially outer leg 5 and the radial leg 7 are provided with a unitary, merged friction reducing surface coating which is made of a PTFE foil.
The radial flange 25 on its side facing the surface 14 of the machine element to be sealed 15 has a supporting projection 39 which extends under the sealing lip 2 and projects axially in direction of the space to be sealed. Undesirably large shape changes of the sealing collar 1 during the intended use are prevented in that the sealing collar 1 is supported in the region of its sealing lip 2 by the supporting projection 39.
Figures 9 and 10 respectively show an exemplary embodiment which essentially corresponds to the one of Figure 6, whereby the backing rings 29 used as the supporting bead 26 are of different construction.
In Figure 9, the backing ring 29 is rectangular and prevents an extruding of the sealing lip 2 into the seal gap as well as a flipping over of the sealing lip 2 towards the ambient 34. The rectangular geometry of the backing ring 29 can be cost efficiently and reliably manufactured.
In Figure 10, the backing ring 29 is wedge shaped and also consists of a polymeric material, which provides good wear and strength properties. Even at low operating pressures, the backing ring 29 radially spaced apart surrounds the surface 14 of the machine element to be sealed 15, whereby the total friction moment is very small as well as the friction heat generated. At higher system pressures within the space to be sealed, this backing ring 29 also prevents the extrusion of the elastomeric material of the sealing collar 1 towards ambient.
Figure 11 shows an eleventh exemplary embodiment, wherein the supporting ring forms part of a housing cover 3.3.
Figure 12 shows an exemplary embodiment of a sealing ring similar to the afore-described exemplary embodiments, whereby however no garter spring 13 is used.
This variant has the advantage that the seal generates smaller friction during pressure free operation, since the initial contact force is generated only by the overlapping of the sealing lip 2 with the surface 14 of the machine element to be sealed 15. Overall, the sealing lip thereby exhibits less wear and improved efficiency.
In all illustrated exemplary embodiments, the first and second cone angles 22, appear to be of the same size. The sealing lip 2 is formed in each of the exemplary embodiments by two mutually intersecting conical surfaces 20, 21, whereby the first cone angle 22 defined by the axis 24 of the machine element to be sealed 15 and the first conical surface 20 facing away from the space to be sealed is at most 10%
smaller than the second cone angle 23 defined by the axis 24 and the second conical surface 21 facing the space to be sealed 3.
By positioning the supporting bead 26 partially as a backing ring 29, the ratio of the length 27 of the first conical surface 20 to the length 28 of the second conical surface 21 is 0.3 to 0.8 in the illustrated exemplary embodiments.
Figure 13 shows an exemplary embodiment wherein the axial projection 35 is coated on its inner side with an elastomer 37. This is advantageous in that larger radial tolerances of both the stiffening ring 4 as well as the supporting ring 10 are without negative effect, whereby the rings 4,10 can be more cost effectively manufactured. As in the embodiment of Figure 8, the radial flange 25 of the supporting ring 10 is provided on its side facing the surface 14 of the machine element to be sealed 15 with a supporting projection 39 which projects axially in direction of the space to be sealed 3 and extends under the sealing lip 2.
Figure 14 shows a further exemplary embodiment, which is distinguished from the ones described before in that the sealing collar 1 is not C-shaped.
Furthermore, the supporting ring 10 extends radially outwardly and can center itself in the aggregate to be sealed.
In the exemplary embodiments shown, the sealing lip 2 in the manufactured condition of the sealing ring as seen in longitudinal section of the sealing ring has an overlap 30 with the surface 14 of the machine element to be sealed 15, which overlap is smaller than the radial spring stroke 31 of the outer axial leg 5 corresponding to the radial spacing 11 between the outer circumferential surface 8 of the axial leg 5 and the radially outwardly adjacent axial flange 32 of the supporting ring 10. This holds true for all exemplary embodiments, except for the exemplary embodiment of Figure 2, wherein no radial spring stroke is provided. By way of the described relationship between the overlap and the radial spacing 11/the corresponding spring stroke 31, it is ensured that a radial spring stroke is maintained even when the sealing ring is mounted on the machine element to be sealed.
Figures 15 and 16 each illustrate an exemplary embodiment of a seal arrangement in accordance with the invention, whereby each of the sealing arrangements includes two sealing collars l .l, 1.2 of elastomeric material and whereby each of the sealing collars 1. l, 1.2 includes a sealing lip 2.1, 2.2. The sealing arrangements are shown in the manufactured, un-installed condition, wherein the machine element to be sealed 15 is in the form of a shaft and shown in broken lines. The sealing of the spaces to be sealed 3.1, 3.2 is achieved in that the sealing lips 2.1, 2.2 sealingly engage the machine element to be sealed 15 under radial tension. The pressure in the spaces to be sealed 3.1, 3.2 is comparatively higher than ambient pressure.
Each of the sealing collars 1.1, 1.2 is provided with a supporting ring 10.1, 10.2 of tough ductile material, which ring in the illustrated exemplary embodiments is constructed as a deep-drawn angled ring made of metallic material.
The sealing collars 1.1, 1.2, when viewed in longitudinal section of the sealing arrangement, are essentially C-shaped and open in axial direction towards the respective space to be sealed 3.1, 3.2. The first supporting ring 10.1 is provided with a first radial leg 25.1 and a first axial flange 32.1, the second supporting ring 10.2 with a second radial leg 25.2 and a second axial flange 32.2. Both sealing rings are combined to a pre-assembled unit 40.
For the sealing of axially adjacent spaces 3.1, 3.2 the two sealing rings are positioned mirror symmetrical to an imaginary radial plane 41. According to the embodiment of Figure 1, both radial flanges 25.1, 25.2 are relatively non-rotatably connected with one another, in this exemplary embodiment by spot welding. In contrast, the first and second supporting rings 10.1 and 10.2 shown in Figure 2 are formed as one unit and of the same material and therefore have a common radial flange 25.
Each of the sealing collars 1.1, 1.2 respectively has a radially outer axial leg 5.1, 5.2 and a radially inner axial leg 6.1, 6.2, whereby the axial legs 6.1, 6.2 are connected by a respective radial leg 7.1, 7.2 on their side axially facing away from the space to be sealed 3.1, 3.2. The outer axial leg 5.1, 5.2 of each sealing collar 1.1, 1.2 is only on the side axially facing the space to be sealed 3.1, 3.2 connected with the free end of the respective axial flange 32.1, 32.2 of the corresponding supporting ring 10.1, 10.2. The respective outer circumferential surface 8.1, 8.2 of the respective outer axial leg 5.1, 5.2 and the end faces 9.1, 9.2 of the respective radial flange 7.1, 7.2 axially facing away from the respective space to be sealed 3.1, 3.2 are un-bonded to the respective supporting ring 10.1, 10.2. Only with such a construction are the sealing lips 2.1, 2.2 especially flexible in radial direction in order to balance eccentricities or out-of round running of the machine element to be sealed. The supporting rings 10.1, 10,2 are closely adjacent with their radial flanges 25, 25.1, 25.2 to the surface 14 of the machine element to be sealed 15, so that the radial gap 38, 38.1, 38.2 in the illustrated examples has only a width of 0.03 to 0.08 mm. Gap extrusion of the elastomeric material of the sealing collar into the radial gaps 38, 38.1, 38.2 is thereby substantially prevented even during the sealing of very high pressures in the range of about 200 bar.
Furthermore, the friction moment is reduced with such a construction. The heat generation in the region of the two sealing lips 2.1, 2.2 is thereby reduced to a minimum.
The afore-described un-bonded association of the outer circumferential surfaces 8.1, 8.2 of the respective outer axial leg 5.1, 5.2 and of the end faces 9.1, 9.2 of the radial legs 7.1, 7.2 respectively facing away from the space to be sealed 3.1, 3.2, with the respective supporting rings 10. l, 10.2 is the same in the embodiments illustrated here. The outer circumferential surfaces 8.1, 8.2 and the end faces 9.1, 9.2 are positioned at a spacing 1 l.l, 11.2, 12.1, 12.2 to the respective supporting rings 10.1, 10.2.
Upon a corresponding elevated pressure within the spaces to be sealed 3.1, 3.2 and/or upon eccentricities and/or upon an out-of round running of the machine element to be sealed 15, the outer circumferential surfaces 8.1, 8.2 and the end faces 9.1, 9.2 can engage the respective supporting rings 10.1, 10.2.
In the illustrated exemplary embodiments, the respectively first cone angle 22.1, 22.2 and the respectively second cone angle 23. l, 23.2 appear to be of the same size. The sealing lips 2. l, 2.2 are formed in each of the exemplary embodiments respectively by two mutually intersecting conical surfaces 20.1, 21.1, 20.2, 21.2, whereby the first cone angle 22.1, 22.2 defined by the axis 24 of the machine element to be sealed 15 and the first conical surface 20.1, 20.2 facing away from the space to be sealed 3.1, 3.2 is at most 10%
smaller than the second cone angle 23.1, 23.2 defined by the axis 24 and the second conical surface 21.1, 21.2 facing the space to be sealed 3.1, 3.2.
In the exemplary embodiments shown, the sealing lips 2.1, 2.2 in the manufactured condition of the sealing ring as seen in longitudinal section of the sealing ring have an overlap 30 with the surface 14 of the machine element to be sealed 15, which overlap is smaller than the radial spring stroke 31.1, 31.2 of the respective outer axial leg 5.1, 5.2 corresponding to the radial spacing 1 l.l, 11.2 between the respective outer circumferential surface 8.1, 8.2 of the axial leg 5.1, 5.2 and the radially outwardly adjacent axial flange 32.1, 32.2 of the supporting ring 10.1, 10.2. By way of the relationship between the overlap 30.1, 30.2 and the radial spacing 11.1, 11.2/the corresponding spring stroke 31.1, 31.2, it is ensured that a radial spring stroke 31.1, 31.2 is maintained even when the sealing ring is mounted on the machine element to be sealed.
In the embodiment of Figure 15, the first supporting ring 10.1 is provided with a supporting projection 39 which protects the inner axial leg 6.1 from undesired high mechanical loads, even under very high pressure, for example in the range of 200 bar, which can be present in the space to be sealed 3.1.
A unitary construction of stiffening ring and supporting ring is shown in Figure 1 ~.
Claims (48)
1. Sealing ring for sealing a space to be sealed about a machine element to be sealed, comprising a sealing collar made of elastomeric material;
at least one sealing lip on the sealing collar for sealing the space to be sealed;
a stiffening ring of tough ductile material connected with the sealing collar, the sealing collar when viewed in longitudinal section of the sealing ring, having a radially outer axial leg connected with the stiffening ring only on the side axially facing the space to be sealed and a radial leg;
a supporting ring connected with the stiffening ring and associated without bonding with an outer circumferential surface of the outer axial leg and an end face of the radial leg axially facing away from the space to be sealed, the supporting ring having a radial flange which is closely spaced from a surface of the machine element to be sealed with a very small intermediate radial spacing.
at least one sealing lip on the sealing collar for sealing the space to be sealed;
a stiffening ring of tough ductile material connected with the sealing collar, the sealing collar when viewed in longitudinal section of the sealing ring, having a radially outer axial leg connected with the stiffening ring only on the side axially facing the space to be sealed and a radial leg;
a supporting ring connected with the stiffening ring and associated without bonding with an outer circumferential surface of the outer axial leg and an end face of the radial leg axially facing away from the space to be sealed, the supporting ring having a radial flange which is closely spaced from a surface of the machine element to be sealed with a very small intermediate radial spacing.
2. Sealing ring for sealing a space to be sealed about a machine element to be sealed, comprising a sealing collar made of elastomeric material;
at least one sealing lip on the sealing collar for sealing the space to be sealed;
a stiffening ring of tough ductile material connected with the sealing collar, the sealing collar when viewed in longitudinal section of the sealing ring, having a radially outer axial leg and a radially inner axial leg, whereby the axial legs on their side axially facing away from the space to be sealed are connected by a radial leg, the outer axial leg is connected with the stiffening ring only on the side axially facing the space to be sealed; and a supporting ring connected with the stiffening ring and associated without bonding with an outer circumferential surface of the outer axial leg and an end face of the radial leg axially facing away from the space to be sealed, the supporting ring having a radial flange which is closely spaced from a surface of the machine element to be sealed with a very small intermediate radial spacing.
at least one sealing lip on the sealing collar for sealing the space to be sealed;
a stiffening ring of tough ductile material connected with the sealing collar, the sealing collar when viewed in longitudinal section of the sealing ring, having a radially outer axial leg and a radially inner axial leg, whereby the axial legs on their side axially facing away from the space to be sealed are connected by a radial leg, the outer axial leg is connected with the stiffening ring only on the side axially facing the space to be sealed; and a supporting ring connected with the stiffening ring and associated without bonding with an outer circumferential surface of the outer axial leg and an end face of the radial leg axially facing away from the space to be sealed, the supporting ring having a radial flange which is closely spaced from a surface of the machine element to be sealed with a very small intermediate radial spacing.
3. Sealing ring according to claim 2, wherein the sealing collar when viewed in longitudinal section of the sealing ring is essentially C-shaped and axially open towards the space to be sealed.
4. Sealing ring according to one of claims 1 to 3, wherein the radial width of the radial gap is 0.03 to 0.2mm.
5. Sealing ring according to claim 4, wherein the radial width of the radial gap is 0.03 to 0.12mm.
6. Sealing ring according to one of claims 1 to 5, wherein the supporting ring is made of a polymeric material.
7. Sealing ring according to one of claims 1 to 6, wherein the radial flange on its side facing the surface of the machine element to be sealed has a supporting projection protruding axially toward the space to be sealed and extending at least partly under the sealing lip.
8. Sealing ring according to one of claims 1 to 7, wherein the outer circumferential surface and the end face are positioned spaced apart adjacent the supporting ring for engagement therewith.
9. Sealing ring according to one of claims 1 to 8, wherein the outer circumferential surface rests against the supporting ring and only the end face is positioned spaced apart adjacent the supporting ring for engagement therewith.
10. Sealing ring according to one of claims 1 to 9, wherein the stiffening ring and the supporting ring are respectively separately produced and positively connected with one another.
11. Sealing ring according to one of claims 1 to 9, wherein the stiffening ring and the supporting ring are respectively separately produced and non-positively connected with one another.
12. Sealing ring according to one of claims 1 to 11, wherein the stiffening ring and the supporting ring are merged into one another and made of the same material.
13. Sealing ring according to one of claims 1 to 12, wherein at least one of the stiffening ring and the supporting ring is made of a metallic material.
14. Sealing ring according to one of claims 1 to 13, wherein at least one of the stiffening ring and the supporting ring is made of a polymeric material.
15. Sealing ring according to one of claims 1 to 14, wherein the inner axial leg is radially outwardly surrounded by a garter spring for increasing the contact pressure of the sealing lip with the surface of the machine element to be sealed.
16. Sealing ring according to one of claims 1 to 15, wherein at least one of the outer axial leg, the radial leg and the supporting ring are provided with a friction reducing surface coating on respectively opposing surfaces.
17. Sealing ring according to claim 16, wherein the surface coating is a PTFE
foil.
foil.
18. Sealing ring according to claim 15, wherein the surface coating is a lacquer.
19. Sealing ring according to one of claims 1 to 18, wherein the sealing lip is formed by two mutually intersecting conical surfaces, a first cone angle defined by an axis of the machine element to be sealed and a first of the conical surfaces facing away from the space to be sealed is at most 10° smaller than a second cone angle defined by the axis and a second of the conical surfaces facing the space to be sealed.
20. Sealing ring according to one of claims 1 to 19, wherein the supporting ring is formed as an angled ring having a radial flange and an axial flange.
21. Sealing ring according to claim 19, wherein the first conical surface has a supporting bead on the side axially facing the radial flange of the supporting ring, and the ratio of the length of the first conical surface to the length of the second conical surface is 0.3 to 0.8.
22. Sealing ring according to claim 21, wherein the supporting head is merged with the sealing collar and made of the same material.
23. Sealing ring according to claim 21, wherein the supporting bead is constructed as a separate backing ring which is positively connected with the sealing collar.
24. Sealing ring according to claim 21, wherein the supporting bead is constructed as a separate backing ring which is non-positively connected with the sealing collar.
25. Sealing ring according to claim 21, wherein the supporting bead is constructed as a separate backing ring which is positioned between the sealing collar and the supporting ring without bonding.
26. Sealing ring according to one of claims 23 to 25, wherein the backing ring is made of a PTFE compound.
27. Sealing ring according to one of claims 1 to 26, wherein in the manufactured condition of the sealing ring the sealing lip as seen in longitudinal section of the sealing ring has an overlap with the surface of the machine element to be sealed, which overlap is smaller than the radial spring stroke of the outer axial leg corresponding to the radial spacing between the outer circumferential surface of the axial leg and the radially outwardly adjacent axial flange of the supporting ring.
28. Sealing ring according to one of claims 1 to 27,wherein the supporting ring forms part of a housing cover.
29. Sealing ring according to one of claims 1 to 28, wherein the supporting ring is provided with a protecting lip positioned on that side of the radial flange facing away from the sealing lip and sealingly surrounding the surface of the machine element to be sealed.
30. Sealing arrangement, comprising a first sealing ring according to one of claims 1 to 29, including a first sealing collar of elastomeric material with at least one sealing lip for the sealing of a first space to be sealed about a machine element to be sealed and a first supporting ring of tough ductile material connected with the sealing collar and having a first radial flange and a first axial flange; and a second sealing ring according to one of claims 1 to 29, including a second sealing collar of elastomeric material with at least one sealing lip for the sealing of a second space to be sealed axially adjacent the first space to be sealed and a second supporting ring of tough ductile material connected with the sealing collar and having a second radial flange and a second axial flange; whereby the first and second sealing rings are combined into a pre-assembled unit.
31. Sealing arrangement according to claim 30, wherein the first and second sealing rings are positioned minor symmetrical to an imaginary plane.
32. Sealing arrangement according to claim 30 or 319 wherein the first and second supporting rings have a common radial flange and are constructed as one unit and of the same material.
33. Sealing arrangement according to claims 30 or 31, wherein the first and second radial flanges are connected relatively non-rotatably with one another.
34. Sealing arrangement according to one of claims 30 to 33, wherein each of the sealing collars when viewed in longitudinal section of the sealing arrangement is essentially C-shaped and open in axial direction towards the respective space to be sealed, each of the sealing collars respectively having a radially outer axial leg and a radially inner axial leg, whereby the respective axial legs of each collar are connected by a respective radial leg on the side axially facing away from the respective space to be sealed, the outer axial leg of each sealing collar being only on the side axially facing the space rspectively to be sealed connected with a free end of the respective axial flange of the corresponding supporting ring, the respective outer circumferential surface of the respective outer axial leg and the end face of the respective radial flange axially facing away from the respective space to be sealed being associated with but unbonded to the respective supporting ring.
35. Sealing arrangement according to one of claims 30 to 34, wherein the supporting rings respectively include a radial flange, wherein the radial flanges are positioned closely adjacent the surface of the machine element to be sealed with only a small intermediate gap.
36. Sealing arrangement according to claim 35, wherein the radial width of the intermediate gap is 0.01 to 0.2mm.
37. Sealing arrangement according to claim 35, wherein the radial width of the intermediate gap is 0.03 to 0.08mm.
38. Sealing arrangement according to one of claims 30 to 37, wherein the respective outer circumferential surface and the respective end face are positioned spaced apart adjacent the respective supporting ring for engagement therewith.
39. Sealing arrangement according to one of claims 30 to 38, wherein the respective outer circumferential surface rests against the supporting ring and only the respective end face is positioned spaced apart adjacent the respective supporting ring for engagement therewith.
40. Sealing arrangement according to one of claims 30 to 39, wherein the supporting rings are respectively made of a metallic material.
41. Sealing arrangement according to one of claims 30 to 40, wherein supporting rings are respectively made of a polymeric material.
42. Sealing arrangement according to one of claims 30 to 41, wherein the respective inner axial leg is radially outwardly surrounded by a garter spring for increasing the contact pressure of the respective sealing lip with the surface of the machine element to be sealed.
43. Sealing arrangement according to one of claims 30 to 42, wherein at least one of the respective outer axial legs, the respective radial legs and the respective supporting rings is provided with a friction reducing surface coating on respectively opposing surfaces.
44. Sealing arrangement according to claim 43, wherein the surface coating is a PTFE
foil.
foil.
45. Sealing arrangement according to claim 44, wherein the surface coating is a lacquer.
46. Sealing arrangement according to one of claims 30 to 45, wherein each of the sealing lips is formed by two mutually intersecting conical surfaces, a first cone angle defined by an axis of the machine element to be sealed and a first of the conical surfaces facing away from the respective space to be sealed is at most 10%
smaller than a second cone angle defined by the axis and a second of the conical surfaces facing the respective space to be sealed.
smaller than a second cone angle defined by the axis and a second of the conical surfaces facing the respective space to be sealed.
47. Sealing arrangement according to one of claims 30 to 46, wherein the supporting rings are respectively formed as an angled ring having a radial flange and an axial flange.
48. Sealing arrangement according to one of claims 30 to 47, wherein in the manufactured condition of the respective sealing ring the respective sealing lip as seen in longitudinal section of the respective sealing ring has an overlap with the surface of the machine element to be sealed, which overlap is smaller than the respective radial spring stroke of the respective outer axial leg corresponding to the respective radial spacing between the outer circumferential surface of the respective axial leg and the radially outwardly adjacent axial flange of the respective supporting ring.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE10305273.2-12 | 2003-02-08 | ||
| DE10305273 | 2003-02-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2457167A1 true CA2457167A1 (en) | 2004-08-08 |
Family
ID=32841622
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002457167A Abandoned CA2457167A1 (en) | 2003-02-08 | 2004-02-09 | Sealing ring and seal arrangement including two such sealing rings |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2457167A1 (en) |
-
2004
- 2004-02-09 CA CA002457167A patent/CA2457167A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |