DE10050983B4 - Axial shaft seal in a housing bore with a firmly connected to the shaft circumferential inner part - Google Patents

Abstract

Axial shaft seal in a housing bore with a circumferential inner part which is firmly connected to the shaft and which has an outwardly facing annular disc made of PTFE, which bears sealingly on a mating ring on the outer part, characterized in that the inner part (4) consists of a stiffening ring (7) Metal is on the side of the shaft (3) facing and facing away from an elastomer support (8) and is sealingly attached to the shaft (3), and that a counter ring (14) with a radial inside (13) as a flat contact surface for the annular disc (10) is provided, to which the conical annular disc (10) is aligned, the inner edge (1) of which is embedded in the elastomeric layer (8) by vulcanization and the outer edge (12) on the inside (13) of the counter ring (14), and at higher speeds a centrifugal force-related reduction in the contact pressure on the outer edge (12) of the annular disc (10) occurs on the inside (13) of the counter ring (14).

Description

Both shaft seals and axial shaft seals are used to seal shaft bushings. The seals are intended to prevent oil from escaping to the outside or dirt particles from entering the interior of the housing from the outside. Here, seals are used in which the seal is fixed in the housing bore and the sealing lip sealingly surrounds the rotating shaft. Also used are cassette seals, which can be executed both as a radial and axial seal and in which an inner part or an outer part is provided, which serves as a counter surface for the sealing lips.

State of the art

By the EP 0 525 288 B1 For example, a cassette seal has become known in which an inner part fastened on a shaft cooperates with an outer part inserted in the housing bore as an axial shaft seal. However, this embodiment has the disadvantage that the sealing lip is stationary and thus has a high friction.

Another cassette seal is from the EP 0 036 281 B1 refer to. There, the seal is achieved via a sealing ring, which is arranged floating between two axially opposite mating surfaces. The sealing ring has a few radially outwardly diverging, opposite sealing lips, which rest resiliently on the likewise radially diverging mating surfaces of mounted on the shaft or on the housing housing rings. The free-floating arrangement of acting in both axial directions sealing ring can lead to uncontrolled vibrations in runout of the shaft.

Furthermore, by the U.S. Patent 4,513,976 an axial shaft seal has become known, in which a radially aligned annular disc made of PTFE is attached to an inner part fixed to the shaft, which, when mounted in an inclined position, rests against an opposing ring with a conical mating surface secured to the housing. In this case, the annular disk comes to rest against the counter surface directed towards the surroundings. This design has the consequence that increases with increasing speed of the contact pressure of the annular disc on the mating surface, which entails a higher wear.

Presentation of the invention

The invention has for its object to provide an axial shaft seal, which has a low friction and thus a lower oil decomposition, which is inexpensive to manufacture, in particular by a lower requirement for the shaft surface and thus insensitivity to runout of the shaft and against center offset of Has shaft to bore, which gives no wear on the shaft and in which both directions of rotation are possible. The solution of the problem is solved with the features of claim 1. The dependent claims 2 to 13 show advantageous embodiments of the invention.

In the axial shaft seal according to the invention, a firmly connected to the shaft, circumferential inner part is used, which has an outwardly facing annular disc of a polymeric material which bears sealingly against a mating ring present on the outer part. As a polymeric material is understood here primarily PTFE (polytetrafluoroethylene) or a PTFE compound. Also possible are polymers having a similar action, for example sprayable copolymers, such as, for example, FEP (perfluoroethylene propylene) or PFA (perfluoroalcohol copolymer). The counter ring is preferably made of metal.

The inner part is formed from a stiffening ring, in particular made of metal with an at least on the shaft side facing the elastomer pad and is sealingly fixedly mounted on the shaft. The elastomer support is formed from a thermoplastic or thermosetting plastic. The ring disk itself attached to the inner part is held by the elastomer support attached to the reinforcing ring. The elastomer support is designed accordingly, so that it can absorb the inner edge of the annular disc, preferably by vulcanization. The protruding from the support part of the annular disc is conically aligned with the mating ring and is at least with its outer edge region of the mating ring. In this adjacent edge region, which can be referred to as the sealing surface of the annular disc, preferably one or more Rückfördernuten for oil are mounted.

In the present invention, the annular disc acts on the one hand as a slinger and on the other hand in conjunction with the mating ring as an axial sealing disc. There is a centrifugal centrifugal centrifugation of the medium to be sealed from the sealing point and by the Ölrückfördernuten on the annular disc entering the contact zone of the centrifugal disc and flat surface oil is fed back into the oil chamber. At higher speeds, an air cushion forms between the sealing disc and the plane surface, so that there is a practically wear-free operating state.

In a simple embodiment, the counter ring can be formed by the inner surface of a housing cover edge. The housing cover is provided with a protruding edge on which abuts the sealing surface of the annular disc.

Preferably, however, the Axialwellendichtung is provided with a sealingly inserted into the housing bore outer part, which consists of a stiffening ring, preferably made of metal, which is provided at least on its radially outer surface with an elastomer support and has a radially inwardly angled disk part, which the forms planar bearing surface for the annular disc.

For the determination of the annular disc and the mating ring to each other, the outer elastomer support of the stiffening ring of the inner part of the mating ring fitting positioning nubs for a defined mounting bias can have.

It is also possible that the counter ring consists of a support ring which is held with its outer edge in the elastomer support of the inserted into the housing bore stiffening ring of the outer part. In this case, the inner part and the outer part of the seal may consist of approximately comparable parts, the inner part holding the annular disk and the outer part holding the counter ring. By this mounting of the counter ring, the axial contact pressure of the annular disc can also be controlled during axial movements.

It is also possible to perform the seal as a cartridge seal, as desired for many applications. In this case, the stiffening ring of the outer part may have a radially inwardly bent edge, come into contact with the spacer knobs, which are present on the radially outwardly drawn edge of the stiffening ring of the inner part. In this way, the outer and inner parts are held in a predetermined position to each other.

Also possible here is an embodiment in which the outer part is provided on its radially inner side with an annular disc which presses against the mating ring spring ring, which is held by at least one wedge ring with a voltage applied to the spring ring wedge surface. The spring ring used can for example be a helical tension spring. For mounting purposes, it is advantageous if the spring ring and the or the wedge rings are held by a separate retaining ring, wherein the retaining ring can be pressed into the outer part.

The spring ring can also be designed as a wave spring. This wave spring is then held by a clamping ring and between the wave spring and the annular disc, a pressure ring is inserted for uniform force distribution.

Another possibility of fixing the annular disc on the inner part is that the annular disc is held by a bellows-shaped elastomeric approach from the inner part.

Finally, the invention provides for providing the housing with a measuring sensor via which, for example, shaft speed and angle of rotation can be measured. In this case, a multi-pole ring opposite the measuring sensor is attached to the elastomer of the inner part.

The particular advantages of the invention can be seen in the fact that a centrifugally assisted reduction of contact pressure occurs at high speeds and an additional sealing effect occurs by centrifugal centrifugation of the medium to be sealed.

Brief description of the drawing

On the basis of several embodiments, the invention will be explained in more detail below.

It shows:

1 the basic structure of the axial shaft seal with housing cover and sensor,

2 an axial shaft seal with inner and outer part,

3 an axial shaft seal with spring-mounted counter-ring,

4 an axial shaft seal in cassette form with spacer knobs between inner and outer part,

5 an axial shaft seal in cassette form with means for pressing the annular disc,

6 an axial shaft seal in cassette design with clamping ring and wave spring,

7 an axial shaft seal with spring-mounted connection of the annular disc and

8th an axial shaft seal in cassette design with a voltage applied to the annular disc compression spring.

Embodiment of the invention

In the 1 is an axial shaft seal 1 shown in a housing bore 2 is inserted and the one with the shaft 3 firmly connected inner part 4 Has. The housing 5 is through the housing cover 6 completed. The inner part 4 consists of the stiffening ring 7 that of an elastomeric pad 8th is enclosed. The wave 3 facing side of the stiffening ring 7 is like that with the elastomer pad 8th provided that the inner part 4 sealing and tight on the shaft 3 can be attached. In the upper part of the elastomer pad seen in the drawing 8th , which in this case the stiffening ring 7 completely surrounds, is the annular disc 10 held. The ring disk 10 is made of a polymeric material and of conical shape. The inner edge 11 the annular disc 10 is in the elastomeric elastomeric pad 8th embedded. The outer edge 12 the annular disc 10 lies on the inside 13 of the housing cover 6 sealingly. The inside 13 of the housing cover 6 represents in this embodiment, the counter ring 14 for the annular disc 10 This is the case cover 6 with a protruding housing cover edge 15 Mistake. In the housing cover 6 is preferably a sensor 16 inserted with the multipolar wreath 17 on the inner part 4 interacts. In this way, desired data regarding speed or the like can be read. The ring disk 10 can on their sealing surface 18 be provided with one or more known Ölrückfördernuten.

The 2 shows an embodiment in which the inner part 4 in principle has the same structure as the inner part 4 from the 1 , It sits tightly on the shaft 3 on. This is the stiffening ring 7 on its side facing the shaft with the elastomer support 8th Mistake. In the outer elastomer pad 8th the stiffening ring 7 is the ring disk 10 embedded. In the housing bore 2 of the housing 5 is in this case an outdoor part 20 inserted, which consists of the stiffening ring 21 with an elastomer pad attached to its outside 22 and a radially inwardly angled disk part 24 consists. The elastomer pad 22 is on the radially outer surface 23 of the stiffening ring 21 appropriate. The ring disk 10 has the same structure as in 1 portrayed. It lies on the radially inwardly angled disk part 24 of the stiffening ring 21 at. At the housing 5 is the sensor 16 attached, which with a Multipolradkranz 25 that in the elastomeric panel 8th is housed, cooperates. The stiffening ring 7 of the inner part 4 is angled at its outer end, leaving the inner part 4 when mounting on the end face of the shaft 3 comes to rest and is positioned in this way.

At the elastomer pad 8th of the inner part 4 are positioning knobs 30 attached to the disc part 24 come to the plant and the assembly of the inner and outer part 4 . 20 give a defined mounting bias.

The 3 shows an embodiment in which the inner part 4 in its basic structure the inner part 4 after 2 corresponds; the outer part 20 However, it is designed so that it is the mating ring 14 forming support ring 38 keeps resilient. The outer part 20 from a stiffening ring 35 with an elastomeric coating 36 is firmly in the housing bore 2 inserted. The elastomer pad 36 has a radially inward edge 37 in which the support ring 38 with its outer edge 39 is stored. The ring disk 10 lies sealingly against the support ring 38 on, the slightly yielding in the elastomer pad 36 is held. The sensor 16 acts as in 2 described with the multipole wheel 25 in the elastomeric layer 8th of the inner part 4 together.

In the 4 is the axial shaft seal 1 executed as a cassette seal. This is the stiffening ring 40 of the outer part 20 with the radially inwardly bent edge 41 provided on the spacer studs 42 come to the plant. The stiffening ring 7 of the inner part 4 is with a radially outwardly drawn edge 43 provided on which the spacer studs 42 are attached. All other parts of this figure correspond to the embodiment of the 2 ,

Another possibility of forming the axial shaft seal 1 in cassette form is the 5 refer to. The inner part 4 and the outer part 20 are comparable to the 2 , The same goes for the sensor 16 and the multipole wheel 25 , In addition, in this embodiment, in the outer part 20 a retaining ring 50 inserted, which is a spring washer 51 and two wedge rings 52 and 53 absorbs and in this way the annular disc 10 to the mating ring 24 presses. The wedge rings 52 and 53 are with the wedge surfaces 54 and 55 Mistake. As a spring washer 51 a helical tension spring is used.

The 6 shows a cassette seal, wherein the spring ring 51 a wave spring is. This is in the same way as in the 5 , the ring disk 10 to the mating ring 24 pressed. The wave spring 51 is from a clamping ring 50 held. Between the wave spring 51 and the washer 10 is a pressure ring 56 inserted. The cassette seal in the present case of two interlocking U-shaped stiffening rings 7 . 21 made of elastomeric pads 8th . 22 are coated. The ring disk 10 is in the elastomer pad 8th kept and distance knobs 42 are on the circumference of the outer part 20 the cassette seal attached. The sensor 16 is used in this case in the oil room.

The example of 7 shows a simplified embodiment for the axial shaft seal 1 in which the annular disc 10 from a bellows-shaped elastomeric approach 60 on the inner part 4 is held. The bellows-like approach 60 serves to compensate for the axial movement between the housing 5 and the wave 3 ,

The 8th shows an embodiment in which the annular disc 10 by a compression spring 61 to the mating ring 24 is pressed. The compression spring 61 clings to the ring disk 10 at. Like the ring disk 10 is she in the elastomer 8th held. It can be designed as a tongue spring. All other parts of the 8th correspond to those of 6 ,

The particular advantage of the invention is that a centrifugally assisted reduction of the contact pressure on the counter surface, with simultaneous increasing centrifuging takes place as a sealing aid, as a function of the rotational speed of the shaft.

Claims (13)

Axial shaft seal in a housing bore with a shaft fixedly connected to the circumferential inner part, which has an outwardly facing annular disc made of PTFE, which bears sealingly against a mating ring present on the outer part, characterized in that the inner part ( 4 ) of a stiffening ring ( 7 ) consists of metal on its the shaft ( 3 ) facing and facing away from an elastomeric pad ( 8th ) and sealed on the shaft ( 3 ), and that a mating ring ( 14 ) with radial inside ( 13 ) as a flat bearing surface for the annular disc ( 10 ) is provided, to which the conical annular disc ( 10 ), the same with its inner edge ( 1 ) in the elastomer support ( 8th ) is embedded by vulcanization and with its outer edge ( 12 ) on the inside ( 13 ) of the counter ring ( 14 ) is applied, and with higher speeds, a centrifugal force-reducing the contact pressure of the outer edge ( 12 ) of the annular disc ( 10 ) on the inside ( 13 ) of the counter ring ( 14 ) entry. Axial shaft seal according to claim 1, characterized in that the counter ring ( 14 ) through the inside ( 13 ) of a housing cover edge ( 15 ) is formed. Axial shaft seal according to claim 1, characterized in that the axial shaft seal ( 1 ) with a sealing firmly into the housing bore ( 2 ) inserted outer part ( 20 ), which consists of a stiffening ring ( 21 ), preferably made of metal, which at least on its radially outer surface with an elastomeric pad ( 22 ) and a radially inwardly angled disk part ( 24 ), which has the mating ring ( 14 ). Axial shaft seal according to claim 3, characterized in that the outer elastomer support ( 8th ) of the stiffening ring ( 7 ) of the inner part ( 4 ) on the mating ring ( 24 ) adjacent positioning pimples ( 30 ) has a defined mounting bias. Axial shaft seal according to one of claims 1 to 4, characterized in that the counter-ring ( 14 ) from a support ring ( 38 ), with its outer edge ( 39 ) in the elastomer support ( 36 ) of the housing bore ( 2 ) inserted stiffening ring ( 35 ) of the outer part ( 20 ) is held. Axial shaft seal according to one of claims 1 to 3 and 5, characterized in that the seal ( 1 ) is designed as a cassette seal. Axial shaft seal according to claim 6, characterized in that the stiffening ring ( 40 ) of the outer part ( 20 ) a radially inwardly bent edge ( 41 ), on the spacer knobs ( 42 ) come to rest on the radially outwardly drawn edge ( 43 ) of the stiffening ring ( 7 ) of the inner part ( 4 ) are mounted. Axial shaft seal according to one of claims 6 or 7, characterized in that the outer part ( 20 ) on its radially inner side with a ring disk ( 10 ) to the counter ring ( 24 ) pressing spring ring ( 51 ) provided by at least one wedge ring ( 52 . 53 ) with a spring ring ( 51 ) adjacent wedge surface ( 54 . 55 ) is held. Axial shaft seal according to claim 8, characterized in that the spring ring ( 51 ) is a helical tension spring. Axial shaft seal according to one of claims 8 or 9, characterized in that the spring ring ( 51 ) and the wedge rings ( 52 . 53 ) of a retaining ring ( 50 ) are held. Axial shaft seal according to one of claims 1 to 10, characterized in that the annular disc ( 10 ) by a pressure spring ( 61 ) to the counter ring ( 14 . 24 ) is pressed. Axial shaft seal according to one of claims 1 to 11, characterized in that on the housing ( 5 ) a measuring sensor ( 16 ) and that in the elastomer ( 8th ) of the inner part ( 4 ) the measuring sensor ( 16 ) opposite to a multipole wreath ( 25 ) is available. Axial shaft seal according to one of claims 1 to 12, characterized in that the annular disc ( 10 ) on its sealing surface ( 18 ) is provided with one or more Ölrückfördernuten.

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