阅读说明：本技术 具有轴密封环的轴密封件 (Shaft seal with shaft seal ring ) 是由 扬·施佩希特 塞巴斯蒂安·托伊舍 蒂莫·贝佐克 马蒂亚斯·施皮茨 于尔根·格伦特 于 2019-09-02 设计创作，主要内容包括：一种用于靠着机动车的壳体(13)来密封轴(11)的轴密封件(10),包括具有用于靠着壳体(13)来密封轴(11)的密封唇的轴密封环(16),其特征在于,迷宫式密封件在轴密封环(16)的油侧设置在轴密封环(16)的上游。(A shaft seal (10) for sealing a shaft (11) against a housing (13) of a motor vehicle, comprising a shaft sealing ring (16) with a sealing lip for sealing the shaft (11) against the housing (13), characterized in that a labyrinth seal is arranged upstream of the shaft sealing ring (16) on the oil side of the shaft sealing ring (16).)

1. A shaft seal (10) for sealing a shaft (11) against a housing (13) of a motor vehicle, comprising a shaft sealing ring (16) with a sealing lip for sealing the shaft (11) against the housing (13), characterized in that a labyrinth seal is arranged upstream of the shaft sealing ring (16) on the oil side of the shaft sealing ring (16).

2. The shaft seal (10) of claim 1, wherein the labyrinth seal comprises two axially interlocked support bodies.

3. The shaft seal (10) of claim 2, wherein one or both of the supports are partially angled.

4. The shaft seal (10) of claim 2 or 3, wherein one of the supports is fixed relative to a shaft and one of the supports is fixed relative to a housing, such that when the shaft rotates, the two supports rotate relative to each other.

5. The shaft seal (10) of any one of the preceding claims, characterized in that the labyrinth seal comprises a radially extending reinforcement (14, 23) on its oil side.

6. The shaft seal (10) according to any one of the preceding claims, characterized in that the labyrinth seal comprises a contact seal having a sealing lip (17) and a mating surface (28) sealingly interacting with the sealing lip (17).

7. The shaft seal (10) of claim 6 wherein the contact seal is fixed relative to the shaft and the mating surface (28) is fixed relative to the housing.

8. The shaft seal (10) of claim 6 or 7, characterized in that the contact seal is designed and arranged to lift from the mating surface (28) when the shaft is rotated during proper operation.

9. The shaft seal (10) of claim 8, wherein the contact seal has a weakened portion (32) that, due to its size and arrangement, facilitates lifting of the contact seal.

10. The shaft seal (10) of any one of claims 6 to 9, wherein the contact seal is made of an elastomeric material.

11. The shaft seal (10) according to one of the preceding claims, characterized in that the shaft sealing ring (16) consists of a PTFE-containing material at least in the region of its sealing lip.

Technical Field

The invention relates to a shaft seal with a shaft sealing ring having the features of the preamble of claim 1.

Background

In view of stricter emissions regulations, there is a continuing need for shaft seal rings with lower friction for sealing crankshafts. At the same time, it is necessary to ensure sufficient stability of the shaft sealing ring against underpressure and overpressure occurring during operation of the engine, for example in modern gasoline engines, in which considerable underpressure may occur in the crankcase. In the past, friction optimized radial shaft seal rings were used to seal the crankshaft, with pressure stabilization achieved by proper geometry of the seal lip. However, the friction reduction that can be achieved with radial shaft seal rings is limited.

DE 102011114349 a1 discloses a face seal for sealing a crankshaft. Face seals typically have very low friction, but are made up of a relatively large number of individual components, take up a large amount of installation space, and are relatively expensive.

An axial shaft seal ring is known from fig. 5 in DE 10334896 a 1. In this shaft sealing ring, a reliable seal is achieved by three contact-type sealing elements, namely a contact-type dust seal, a contact-type auxiliary seal and a sealing ring, but at the expense of increased friction.

The axial shaft seal ring according to EP 2749796 a1 also comprises a dust lip which is sealingly located on the bearing ring over the axial length, which dust lip, although providing sufficient dust protection, again leads to increased friction. Furthermore, the sealing element has only a low stability with respect to underpressure, since when underpressure is present on the engine side, the sealing lip is moved away from the bearing ring due to weakening in the vicinity of its connection with the reinforcing part, and the sealing function of the sealing lip is then completely lost.

EP 3032148B 1 discloses an axial shaft sealing ring with a sealing lip which interacts sealingly with a radial counter element, wherein a channel is provided on the sealing lip or on the counter element, in which channel pressure is built up when the shaft rotates. Due to this pressure build-up, the contact force of the lip with the mating element drops with the rotation of the shaft until gas friction replaces liquid friction, causing a sudden significant drop in friction.

Disclosure of Invention

The object of the invention is to provide an improved shaft seal with a shaft sealing ring which achieves a reliable sealing of the crankshaft, as low friction as possible and sufficient pressure stability under all operating conditions.

The invention achieves the object by means of the features of the independent claims. Further preferred developments can be found in the dependent claims, the figures and the related description.

According to the main concept of the present invention, a shaft seal with a labyrinth seal is proposed, which is arranged upstream of the shaft sealing ring on the oil side of the shaft sealing ring.

By the proposed solution, the oil from the oil side is kept away from the shaft sealing ring by the labyrinth seal, which is improved as a whole. The shaft sealing ring is thereby exposed to a significantly smaller amount of oil or oil mist, so that the shaft sealing ring operates with a smaller amount of oil mist and thus closer to the preferred dry friction condition. Furthermore, the pressure on the components of the shaft seal can thereby be reduced, which is advantageous with regard to the frictional forces generated. The pressure in the shaft seal required to achieve a certain degree of sealing action can thus be reduced, in particular in comparison with radially sealed shaft seals. Because the labyrinth seal is substantially untouched, the labyrinth seal does not increase friction; only the sealing action of the entire shaft seal is increased and the shaft seal ring is better protected.

A particularly effective labyrinth seal can thus be achieved with respect to the degree of sealing action by means of a labyrinth seal comprising two axially interlocking support bodies. By means of the two supports, highly complex labyrinth geometries can be achieved which cannot be achieved from a manufacturing point of view by means of only one component. Furthermore, the labyrinth seal can be assembled particularly easily by combining two support bodies. Furthermore, by using a support body with a suitable dimensional stability it can be ensured that the labyrinth geometry between the support bodies is maintained even under the operating forces that are acting.

Thus, by one or both supports being angled in sections, a particularly complex labyrinth geometry can be achieved. By the angled shape, a labyrinth seal with mutually angularly oriented labyrinth passages can be realized, so that the oil mist is diverted by one or more diverts and thereby additionally slowed down in the labyrinth seal.

One of the supports is preferably arranged fixed relative to the shaft and one of the supports is arranged fixed relative to the housing, so that the two supports rotate relative to each other upon rotation of the shaft. Due to the proposed improvement, at least two of the opposing walls of the labyrinth passage are rotated relative to each other, whereby the oil mist located in the labyrinth passage is intentionally swirled and the through-flow resistance of the labyrinth seal and the resulting sealing action can be further increased.

It is further proposed to provide a labyrinth seal comprising a radially extending reinforcement on its oil side. The reinforcement makes it possible for the labyrinth seal to be reinforced or dimensionally stabilized in its particular shape with the labyrinth passage, wherein the labyrinth passage is supported by the arrangement of the reinforcement on the oil side, in particular on the inlet side. Furthermore, by means of a suitable shape and arrangement of the reinforcement, already a large proportion of the oil or oil mist can be kept away from the labyrinth seal and thus from the shaft sealing ring, so that the reinforcement further contributes to the sealing action of the shaft seal.

Furthermore, the labyrinth seal may preferably comprise a contact seal having a sealing lip and a mating surface which interacts sealingly with the sealing lip, so that the flow of oil through the labyrinth seal can be further reduced partially or even completely prevented.

It is further proposed that the contact seal is arranged to be fixed relative to the shaft and the mating surface is fixed relative to the housing. The mating surface is thus considered to be static, i.e. stationary, while the contact seal moves relative to the mating surface.

It is further proposed that the contact seal is designed and arranged to lift from the mating surface when the shaft rotates during proper operation. Accordingly, when the shaft is not rotating, the contact seal abuts against the mating surface, thereby completely sealing the flow of oil and thus completely sealing the oil side from the atmosphere side. This is advantageous for pressure tests which are carried out without the shaft rotating, for example in a transmission or an internal combustion engine of a motor vehicle. Furthermore, when the shaft rotates during proper operation, the contact seal is intentionally lifted and thus undergoes a movement that can be used, for example, to return oil mist back toward the oil side, whereby the sealing action can be further improved. Furthermore, the frictional forces acting in the shaft seal during operation and the wear of the shaft seal due to the removal of the contact can be further reduced.

It is further proposed that the contact seal has a weakened portion that, due to size and arrangement, facilitates lifting of the contact seal. The contact seal can thus be produced from a single, homogeneous material, the movement of which is intentionally driven automatically by the forces that occur upon rotation of the shaft and act on the contact seal. The moment at which the part of the seal to be moved is contacted and moved is controlled by the size of the thickness of the wall of the weakening or the size of a specific recess in the weakening and the arrangement of the weakening.

The contact seal can preferably be formed from an elastic material, which is advantageous due to the elastic properties of the elastic material in terms of the sealing action to be achieved and in terms of the mobility of the contact seal.

It is further proposed that the shaft sealing ring is made of a PTFE-containing material at least in the region of the sealing lip of the shaft sealing ring. The PTFE-containing material has particularly good dry friction properties, which can be utilized particularly effectively by the solution according to the invention, i.e. the upstream arrangement of the labyrinth seal and the resulting advantage of keeping away oil mist. Shaft sealing rings with PTFE parts and which are particularly suitable for dry friction are in practice protected against the ingress of oil particles by labyrinth seals and therefore operate in dry operation, so that such shaft seals in combination with labyrinth seals are particularly advantageous.

Drawings

The invention will now be explained on the basis of preferred embodiments with reference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a shaft seal according to a first embodiment of the present invention; and

FIG. 2 is a cross-sectional view of a shaft seal with a closed contact seal according to a second embodiment of the present invention; and

FIG. 3 is a cross-sectional view of a shaft seal with an open contact seal according to a second embodiment of the present invention; and

FIG. 4 is an oblique view of a shaft seal with a contact seal and a first reinforcement; and

fig. 5 shows a view of the shaft seal according to the invention from the oil side.

Detailed Description

The shaft seal 10 serves to seal a shaft 11, in particular a crankshaft, the shaft 11 extending from a sealed oil chamber 27 through an opening 12 in a housing 13 of an internal combustion engine, an electric motor or a transmission of a motor vehicle to an atmosphere-side exterior 25. The housing 13 is formed of, for example, several parts, and has an oil-side holding member 30 and an atmosphere-side holding member 31. The shaft seal 10 is supported radially outside the opening 12 of the housing 13 and radially inside the shaft 11, thereby sealing the annular space between the housing 13 and the shaft 11.

The shaft seal 10 comprises an annular first reinforcement 14 fixed relative to the casing, an annular oil-side second reinforcement 23 fixed relative to the casing, and an annular support 26 fixed relative to the shaft, to which annular support a centrifugal seal 29 is fixed, for example by vulcanization. Furthermore, the shaft seal 10 comprises an annular shaft sealing ring 16 in the form of a PTFE disc, which is clamped between the first reinforcement 14 and a clamping ring 15 supported on an atmosphere-side clamping element 31 for fixation relative to the housing. The first reinforcement members 14, the second reinforcement members 23, and the clamp ring 15 are clamped between a shoulder of the oil-side clamp member 30 and a shoulder of the atmosphere-side clamp member 31, respectively, and are therefore considered to be stationary with respect to the housing 13.

The shaft seal ring 16 has an opening through which the shaft 11 extends. Furthermore, the shaft sealing ring 16 is made of a PTEE-containing elastomer and therefore has the advantageous dry friction characteristics typical of said materials. The first and second reinforcement members 14, 23 form, together with the support body 26 and the contact seal in the form of a centrifugal seal 29, a labyrinth seal which is arranged upstream of the shaft sealing ring 16 with respect to the oil chamber 27. Therefore, in order to flow out of the oil chamber 27 and flow to the atmosphere side outer portion 25, the oil first has to pass through the labyrinth seal before reaching the shaft seal ring 16. Therefore, the shaft seal ring 16 prevents the outflow of oil by the labyrinth seal; in other words, the amount of oil reaching the shaft sealing ring 16 from the oil chamber 27 can be significantly reduced with the labyrinth seal due to the increased through-flow resistance in the labyrinth seal.

On the shaft side, the support body 26 is held together with the spacer washer 18, the reinforcing plate 20 and the spacer ring 21 between a shoulder of the shaft 11 and the chuck 19 fixed on the end face of the shaft 11 and thus rotates together with the shaft 11.

The support body 26 comprises a radially extending main body in the form of an annular disc, a radially outer annular flange projecting axially from the main body and a radially inner annular flange projecting axially from the main body, which together form a U-shaped ring in cross-section. The radially inner annular flange of the support body 26 is fixed to the shaft 11 and serves to fix the support body 26.

The first reinforcement 14, which is fixed relative to the casing, further comprises a radially extending body in the shape of an annular disc, a radially outer annular flange projecting axially from the body, and a radially inner annular flange projecting axially from the body, which together form a U-shaped ring in cross-section. The radially outer annular flange is used to secure the first reinforcement 14 in the housing 13 or to the inside of the oil side clamping element 30.

The support body 26 and the first adding element 14 both have an angular shape due to the annular flange provided thereon and are arranged to be interlocked by the annular flange and to form a through-flow passage with a plurality of turns and increased resistance to the passage of oil mist. Furthermore, when the shaft 11 rotates, the support body 26 rotates together with the shaft 11, so that the wall of the support body 26 also rotates relative to the wall of the addition element 14 fixed to the housing and, in addition, swirls the oil mist present in the through-flow passage of the labyrinth, thereby further increasing the through-flow resistance.

The centrifugal seal 29 is provided on the support body 26 in the form of an elastomer which is vulcanized on the side of the body of the support body 26 from which the annular flanges project, in particular between the annular flanges, i.e. in the U-shape of the support body 26. The centrifugal seal 29 has a weakened portion 32 having a reduced thickness at the connection with the support body 26 and shaped so as to be oriented axially and radially inwards towards the radially inner annular flange of the support body 26 when unloaded. Thus, as can be seen in fig. 1, in the assembled state the support body 26 sealingly abuts with the sealing lip of the centrifugal seal 29 against the radially outer mating surface 28 of the radially inner annular flange of the first reinforcement 14. If the sealing lips are formed in the circumferential direction, the through-flow passage in the labyrinth seal and thus the connection between the oil chamber 27 and the atmosphere-side exterior 25 is completely closed when the shaft 11 is stationary. If the shaft 11 rotates at its operating rotational speed, the support body 26 and the centrifugal seal 29 arranged thereon also rotate at this operating rotational speed. The thickness of the weakened portion 32 is set such that the portion of the centrifugal seal 29 on which the sealing lip is arranged is lifted at the sealing lip from the mating surface 28 under the action of the radial force caused by the rotation of the shaft 11, whereby the friction is reduced and the flow channel in the labyrinth seal is released at least in the range of a small clearance between the sealing lip and the mating surface 28. Although there is a disadvantage that oil mist may flow through the labyrinth at the raised position of the centrifugal seal 29, this disadvantage can be accepted by intentionally achieving the advantage of reducing friction. Due to the multiple turns of the oil mist flow in the labyrinth seal and due to the very small clearance between the sealing lip of the centrifugal seal and the mating surface 28, the flow rate of the oil mist flow through the labyrinth seal from the oil chamber 27 is also very small at the location where the centrifugal seal 29 rises from the mating surface 28; such a flow rate is acceptable in view of the advantages obtained. Furthermore, by means of the radially outward movement of the centrifugal seal 29, the oil mist flow can be conveyed back towards the oil chamber 27 by means of the pressure gradient which is generated, so that the above-mentioned disadvantages can even be compensated.

In addition to the size and arrangement of the weakenings 32 and the shape and arrangement of the centrifugal seal 29, additional design parameters of the centrifugal seal 29 include the mass of the part of the centrifugal seal 29 on which the sealing lips are arranged, the material of the centrifugal seal 29 and its deformation properties, and the rotational speed of the shaft 11.

Furthermore, in order to configure the sealing properties of the labyrinth seal and the centrifugal seal 29 arranged therein, it is also possible to utilize the geometry of the through-flow channel both statically and dynamically (i.e. when the centrifugal seal 29 is moved).

In this respect, the first and second reinforcing elements 14, 23 and the support body 26, which can be considered as dimensionally stable support bodies in particular, are particularly advantageous, since these reinforcing elements and support bodies allow the geometry of the through-flow passage in the labyrinth seal to be maintained. Furthermore, the dynamic centrifugal seal 29 is particularly important because it forms a contact seal with the mating surface 28 on the first reinforcing element 14 when the shaft 11 is stopped; ideally, the centrifugal seal completely separates the oil chamber 27 and the atmosphere-side outer portion 25 in the case of a circumferential sealing lip. In this context, it is advantageous if the mating surface 28 is provided on the dimensionally stable first reinforcing element 14, i.e. on a dimensionally stable support body which is fixed to the housing and which, by virtue of its shape stability, is able to form a dimensionally precise sealing surface even under force. Furthermore, it is advantageous to use a dimensionally stable support body to form a dimensionally accurate labyrinth seal, in particular when using the proposed dynamic centrifugal seal 29, because it is thereby possible to perform the required movements in the dimensionally accurate labyrinth even when the shaft 11 is rotating. In particular, it can thus be ensured that the centrifugal seal 29 is intentionally lifted and loses contact with the mating surface 28 without uncontrolled abutment against the other wall of the labyrinth, by which the friction would be caused to increase again disadvantageously. However, if desired, the centrifugal seal 29 may also be designed alternatively so as to bear against a further mating surface above a certain rotational speed and deliberately reseal the through-flow passage in the labyrinth.

Fig. 2 and 3 show a shaft seal 10 according to a second embodiment of the invention. In particular, in fig. 2 the centrifugal seal 29 is closed, in fig. 3 the centrifugal seal 29 is open. The second embodiment of the shaft seal 10 features a smaller number of individual components, thereby reducing the cost of manufacture and assembly.

In this case, the support body 26 is connected to the shaft 11 by a single reinforcing plate 20. Furthermore, the second reinforcement members 23 are formed as rings, the inner diameter of which extends to the shoulder of the support body 26. A shaft seal ring 16 is secured to the first reinforcement member 14. For fixing the ring, a clamping ring 15 (not shown) may be provided in a manner similar to the first embodiment. The radially inner edge of the shaft seal ring 16 protrudes into a groove of the increasing plate 20 rotationally fixed to the shaft 11 and thereby seals the gap between the increasing plate 20 of the shaft seal 10 and the reinforcement 14 of the shaft seal 10.

The centrifugal seal 29 operates the same as in the first embodiment, and in FIG. 2, the sealing surface of the centrifugal seal sealingly bears against the mating surface 28 of the first reinforcement 14 when the shaft 11 is not rotating. In the position in fig. 3, the shaft 11 is rotating at its operating rotational speed and the sealing surface of the centrifugal seal 29 is pivoted radially outwards, i.e. opened.

In principle in both embodiments the centrifugal seal 29 is designed such that when the shaft 11 is not rotating, the sealing surface of the centrifugal seal abuts against the mating surface 28 and blocks the oil mist from flowing past the labyrinth seal. The centrifugal seal 29 is designed such that when pressure is applied to the oil chamber 27, the sealing surface of the centrifugal seal is pressed against the mating surface 28 and the sealing force is increased. Therefore, when pressure is applied to the oil chamber 27, the sealing action of the shaft seal 10 increases, and in any case, the shaft seal 10 does not open even if the pressure in the oil chamber 27 is increased.

As can be seen in fig. 3, if the shaft 11 rotates at its operating rotational speed, the sealing surface of the centrifugal seal 29 lifts from the mating surface 28. The operating speed is defined by the operating range of the device in which the shaft 11 rotates. Depending on the type of device, this operating range can be a very wide range or a very precisely defined rotational speed range. In summary, it is important that the sealing lip of the centrifugal seal 29 sealingly abuts against the mating surface 28 when the shaft 11 is stopped, while it rises at the operating rotational speed and thereby reduces friction.

Fig. 4 shows the shaft seal 10 of fig. 2 and 3 with the first reinforcement members 14 cut out, as seen from the centrifugal seal 29, i.e. from the atmosphere side 25. In this case, the centrifugal seal 29 is formed by a plurality of individual segments which are separated from one another by the spacers 33, have better mobility through the spacers 33 and can also be lifted individually from the mating surface 28. Furthermore, although a small amount of oil mist can pass through the gap 33, the oil amount is still reduced, because the gap 33 in the centrifugal seal 29 also forms a passage for a labyrinth seal and increases the through-flow resistance of the oil mist compared to solutions known in the prior art.

Fig. 5 shows the shaft seal 10 in fig. 2 and 3, viewed from the side of the oil chamber 27, i.e. from the support body 26. A plurality of uniformly arranged passage openings 34 are provided in the second reinforcement 23 fixed relative to the shell; oil mist from the labyrinth seal can be returned to the oil chamber 27 via the passage opening.