DE102009055647A1 - Cassette seals for radial bearings and installation procedures - Google Patents

Abstract

In summary, the invention relates to a cassette seal for sealing a radial bearing, the cassette seal having two rings which can be moved relative to one another and both rings having a hollow cylindrical part and a radially extending part, the hollow cylindrical parts being radially opposite and the radially extending parts being axially opposite in the operating state , The aim is to increase the effectiveness of the seal and at the same time to enable easy installation of the cassette seals. This is achieved in that an outer radius of the radially extending parts of the second ring is larger than the largest inner radius of the hollow cylindrical part of the first ring and smaller than the outer radius of the hollow cylindrical part of the first ring. This makes it possible, with the same amount of material, to create a labyrinth seal that better protects the inside of the cassette seals and thus also the rolling chamber of the radial bearing from external influences such as moisture and dirt particles.

Description

Field of the invention

The invention relates to a cartridge seal for sealing a radial bearing, wherein the cartridge seal comprises two relatively movable rings and both rings have a hollow cylindrical part and a radially extending part, wherein in the operating state, the hollow cylindrical parts are radially opposite and the radially extending parts axially, wherein the hollow cylindrical portion of the first ring with respect to the axis of rotation has a larger outer radius than any other hollow cylindrical portion of the cartridge seal for placement within a bearing portion of the radial bearing.

State of the art

Background of the invention

Radial bearings consist of a first and a second bearing part, wherein via these bearing parts, a radial force is transmitted and possibly both bearing parts or arranged on these bearing rings raceways, which are provided for guiding the rolling elements of the radial bearing.

This results in the fundamental problem of the design of the seal, which is intended to seal the rolling space in which the rolling elements are located from the outside world of the radial bearing. In the case of radial bearings, which are operated outside of closed rooms, such as wheel bearings, release bearings, etc., there is generally a higher risk of contamination of the rolling room due to dirt particles. These lead to a faster wear of the bearing. For particularly large particles of dirt even to a damage of the raceways (so-called pitting).

In the past, cartridge seals were designed for such difficult operating conditions, which secured the rolling space from penetrating water and dirt particles both by their axial and radial sealing lips, but also by means of two longitudinally L-shaped rings, which together form an annular space leading to the seal the Wälzraumes by means of non-contact gap seals or by means of the already mentioned abradingly fitting, axial and radial sealing lips is provided. Both rings have a hollow cylindrical part, which is connected to the bearing parts, usually by press fit, and thus helps prevent rusting in the axial direction largely. In addition, by the opposite arrangement of the substantially L-shaped rings an advantage in handling or the packaging and stacking of the cassette seal.

Out EP 1 898 132 A1 Various cassette seals are known for wheel bearing applications, which belong to the described generic type and differ substantially by the arrangement of the elastic parts, which form a variety of types of sealing lips.

The problem with this is that sets an installation disadvantage in these compact sealing arrangements. In general, the two rings of the cassette seal are successively attached to the bearing parts by pressing. However, since you can usually do without a radial sealing lip, you run the risk of the radial sealing lip, which should usually insert on the hollow cylindrical part of the second ring to fold during the installation process in the direction of the rolling space. Thus, the radial sealing lip does not reach the intended sealing surface on the second ring, whereby the rolling bearing inevitably fails within a very short time. Unfortunately, this installation error is not visible from the outside, since the last installed second ring blocks the view of the radial sealing lip.

Alternatively, it is conceivable that to avoid the described Umklappung dispensed sealing effect of the cassette seal. This is the case when the radially extending portion of the second ring is directed to the hollow cylindrical portion of the first ring and forms with this a radial sealing gap. This does not exhaust the possibilities of sealing gap formation and is therefore also disadvantageous.

task

Summary of the invention

The object of the invention is therefore to provide a cassette seal, which has both a high sealing effect, but is also easy and safe to install.

The object is achieved by a wheel bearing unit of the type mentioned above in that an outer radius of the radially extending portion of the second ring is greater than an inner radius of the hollow cylindrical portion of the first ring and the outer radius of the radially extending portion of the second ring is smaller than that Outer radius of the hollow cylindrical part of the first ring.

According to the invention it is provided to use a cassette seal for sealing a radial bearing, wherein the cassette seal comprises two relatively movable rings. Both rings have a hollow cylindrical part and a radially extending part, wherein the radially extending part is hereinafter also referred to as a radial part. The hollow cylindrical part and the radial part are integrally connected to each other and form in longitudinal section to the axis of rotation of the radial bearing or the cassette seal substantially each an L-shape, so are substantially perpendicular to each other. Both rings are further arranged such that the hollow cylindrical parts are radially opposite and the radial parts axially.

In the operating state of the hollow cylindrical part of the first ring with respect to the axis of rotation is arranged radially further outward than the hollow cylindrical part of the second ring. Furthermore, the hollow cylindrical part of the first ring also represents the radially outermost hollow cylindrical part of the cassette seal relative to the axis of rotation. The first ring is usually referred to as a so-called sealing ring, wherein the second ring is optionally a so-called slinger. The first ring is mounted on the first bearing part, ideally with the hollow cylindrical part, and the second ring according to the second bearing part, also ideally with its hollow cylindrical part. Both bearing parts or both rings rotate relative to each other, that is, they can be used for example in wheel bearings for passenger cars but also in wheel bearings for trucks use.

The operation of the invention is due to the fact that an outer radius of the radial part of the second ring is greater than the inner radius of the hollow cylindrical part of the first ring. An outer radius of the radial part extends from the axis of rotation to the outer surface of the radial part. The inner radius of the hollow cylindrical portion extends from the axis of rotation to the inner surface of the hollow cylindrical portion having the largest radius of all inner surfaces of the hollow cylindrical portion. Therefore, one could also speak of a largest inner radius.

Furthermore, it is provided according to the invention that the outer radius of the radial part of the second ring is smaller than the outer radius of the hollow cylindrical part of the first ring. It is thus achieved that the radial part with its radial end piece covers the hollow cylindrical part of the first ring at least partially in the axial direction. This cover ensures that an axial force transmission from the second ring to the first ring during the press-fitting operation is possible. It is advantageous if the two mentioned external radii are very close to each other. This is a very small radial sealing gap between the first bearing part, which may be, for example, an outer ring or a hub of a truck, realized. Furthermore, an axial sealing gap is also formed between the end piece of the radial part of the second ring and the axial end of the hollow cylindrical part of the first ring. Advantageously, it is possible to produce a more advantageous gap seal with unchanged material costs.

The axial sealing gap is basically fixed to the relative axial positioning of the two rings to each other. For this purpose, it is proposed to use a press-in tool, which has a conical inner surface which protrudes axially at larger radii, which is elastically stressed during the press-fitting of the radial part of the second ring and a defined angle is moved away from the radial. The conicity of the press-fit tool determines the final distance of the two rings or the size of the axial sealing gap between the end portion of the ring member of the second ring and the axial surface of the hollow cylindrical portion of the first ring. In other words, the axial distance of the press-in at the inner radius of the press tool and the outer radius of the press tool is identical to the width of the axial sealing gap. The elastic stress of the radial part ensures that the radial part springs back into its original position after the press-fitting process and henceforth forms the desired axial sealing gap with the hollow-cylindrical part of the first ring. It should be noted that the conicity is not so strong that the second ring is also stressed inelastic and changes its shape of the force-free state.

Advantageously, it is impossible for a radial sealing lip, which can not be dispensed with in many applications, to be guided away from its associated sealing surface on the second ring or even to be folded over in the direction of the rolling space. This problem is effectively prevented by the simultaneous injection of the two rings. At the same time, you do not have to do without an optimal labyrinth seal.

In an advantageous embodiment, the first ring has an elastic part with a radial sealing lip. The elastic part can simultaneously also other sealing lips, for. B. form axial sealing lips or static seals to the bearing parts. In addition, in order to realize a better posture of the elastic member, the first ring may locally deviate in its radial part from the strict radial orientation.

Advantageously, the radial sealing lip bears sealingly against the hollow cylindrical part of the second ring. Thus, the second ring takes on a dual function, since this forms both a labyrinth seal, but also a stainless counter surface, or sealing surface for the radial sealing lip on the hollow cylindrical part provides. This can for example be done by the second ring (as well as possibly the first ring) is made of a stainless material.

Advantageously, the hollow cylindrical parts of the rings are provided for fastening the rings. Thus they also assume a fastening function (in addition to the sealing gap formation or the provision of a sealing surface).

Advantageously, the radial part - also called the radially extending part - of the second ring with a bearing ring or a wheel hub forms a radial gap seal. As a radial gap seal, a sealing gap is considered, which is defined by at least two radii in its extension and can extend axially as desired.

Advantageously, the radial part of the second ring forms an axial sealing gap with the hollow cylindrical part of the first ring. In this case, an axial distance of the limiting surfaces is set to each other, wherein the radial extent is not fixed and can extend as desired.

In an advantageous embodiment, a radial end piece of the radial part of the second ring is provided for axial force transmission to the hollow cylindrical part of the first ring during the press-fitting process. This is particularly advantageous when the axial surface overlap of the first and second ring is particularly large, whereby a low surface density is possible, which avoids damage to the cartridge seal during the Einpressvorgangs.

When installing an embodiment of the cartridge seal of the present invention in a radial bearing, the cartridge seals having a radial sealing lip supported by the first ring and sealingly seated on a hollow cylindrical portion of the second ring, a press tool having a conical axial outer surface is used. The conical, axial outer surface protrudes axially for larger radii than for smaller radii. The power transmission takes place from the press-in tool in the axial direction on the elastically stressed radial part of the second ring, wherein the second ring acts as an installation aid for the first ring. The hollow cylindrical portion of the second ring is pressed axially directly by the press tool, but the hollow cylindrical portion of the first ring indirectly via the radial part of the second ring. During the press-fitting process, the radially outer end piece of the radial part of the second ring is displaced exactly by the width of the axial sealing gap to be produced between the end piece and the hollow cylindrical part of the first ring. Thus, the hollow cylindrical parts and the radial part of the first ring are already in the position they should occupy in the operating state of the radial bearing, in particular wheel bearing. Only the radial part of the second ring is deflected during the press-in process by a certain angle from the starting position, which also represents the position in the operating state. As soon as the press-fit tool is moved back in the axial opposite direction, the ring part of the second ring is elastically released and moves to its operating position.

Advantageously, cartridge seals can be installed with a seal labyrinth just as advantageous. The labyrinth here forms a pre-seal, which are possibly provided with one or more gutters and annular sealing gaps with axial and / or radial directional proportion. At least one gap of the labyrinth can be temporarily closed during the Einpressvorgangs due to the elastic stress of the second ring with respect to the first ring during the installation Vorgans.

Further advantageous and embodiments of the invention can be taken from the description of the figures and / or the subclaims.

In the following the invention will be described and explained in detail with reference to the embodiments illustrated in the figures.

Show it:

1 an installed cassette seal,

2 the cassette seal off 1 before installation,

3 the cassette seal off 1 during the installation,

4 the cassette seal off 1 after installation, and

5 the cassette seal off 1 during pre-assembly.

embodiment

Description of the drawings

1 shows an installed cassette seal. The cassette seal is between a first bearing part 1 and a second bearing part 2 installed, wherein it is at the first bearing part 1 for example, an outer ring or a hub and the bearing part 2 for example can act around an inner ring or alternatively also to a wheel hub.

The radial parts of the two rings 3 . 4 are axially opposite, with an axial sealing lip between them 8th located by an elastic part 5 is formed, in turn, from the radial part of the first ring 4 will be carried. The radial part of the first ring 4 lies between the radial part of the second ring 3 and the non-illustrated rolling elements of the radial bearing, which carry their load in the radial direction to the axis of rotation R and are guided to runways in the bearing parts 1 . 2 are provided or in parts, with the bearing parts 1 . 2 are positively connected.

The rolling elements are located in the only partially imaged rolling space, which is sealed by the cassette seal in the axial direction. The sealing effect mainly results from the spring-loaded radial sealing lip 7 forth, passing through the axial sealing lip 8th is protected. The radial sealing lip 6 prevents the ingress of moisture, for example, by rusting under the hollow cylindrical part of the second ring 3 can penetrate.

Advantageously, the radially extending radial part of the second ring form 3 and the first bearing part 1 , which may be a rotating bearing part, a radial sealing gap 11 which is in an axial sealing gap 12 between the tail 13 the radial part of the second ring 3 and the hollow cylindrical part of the ring 4 passes. This creates a labyrinth seal, which advantageously prevents moisture and dirt particles to the axial sealing lip 8th or even to the radial sealing lip 7 penetrate, if the axial sealing lip 8th should no longer be sealing due to material wear.

It can be seen that the outer radius R _{a1 of} the radial part of the second ring 3 with respect to the axis of rotation within the interval between outer radius R _a2 and inner radius R _i , ie R _a2 > R _a1 > R _i

The outer radius R _a2 is the outer radius of the hollow cylindrical portion of the first ring, so the radially outermost hollow cylindrical portion of the entire cassette seal. The inner radius R _i, however, is the largest inner radius of this hollow cylindrical part. It is advantageous if the two outer radii are approximately equal: R _a2 ≈ R _a1 .

This results in a particularly small radial sealing gap 11 and for the press-fit over the radial part of the second ring 3 there is enough axial surface overlap.

2 shows the cassette seal 1 before installation.

The used press tool 9 is on the whole ring-shaped, but has a conical pressing surface oriented in the axial direction of the cassette seal 14 on, which protrudes axially larger at larger radii in the direction of the cassette to be installed and therefore in the radially outer region with the radial part of the second ring 3 Contact first before pressing. The radial part of the second ring 3 is elastically stressed and inclines slightly in the direction of the rolling space, or in the direction of the first ring. If the press-in force is increased, the press-in tool contacts 9 the radial part of the second ring 3 and this in turn the hollow cylindrical part of the first ring 4 , bringing both rings 3 . 4 at the same time in the radial gap between the first bearing part 1 and the second bearing part 2 can be pressed so that both rings 3 . 4 be attached by their hollow cylindrical parts by means of a press fit to the respective bearing part.

At the latest when both hollow cylindrical parts of the two rings in contact with the bearing parts 1 . 2 stand, is the radial part of the second ring 3 at the conical insertion length 14 Plan, so takes the same angle to the radial, as the conical press-fit 14 in longitudinal section to the rotation axis R.

In this process lie the radial sealing lip 7 and the axial sealing lip 8th on, whereby a folding of one of the two lips can be advantageously avoided because it always rests on the sealing surface during the pressing.

3 shows the cassette seal 1 during the installation. The final operating position of the cartridge seals is not yet reached, however, it can be clearly seen that the tail 13 the radial part of the second ring 3 still with both the radially outer end of the press tool 9 , as well as with the hollow cylindrical part of the first ring 4 in contact.

The press tool 9 is already on the way back in the axial opposite direction to the press-in direction. The hollow cylindrical parts are already at the intended position for operation. Only the radial part of the second ring 3 is still in the elastically stressed state. However, this will spring back in the axial direction, so that the axial sealing gap 12 can be formed and the outer surface of the radial part of the second ring 3 axially closes with the outer surfaces of the bearing parts. This prevents the spray from the outer surface a way into the radial gap 11 Can be found.

4 shows the cassette seal 1 after installation, with the radial part of the second ring 3 fully spring back and the press tool 9 can be deducted.

5 shows the cassette seal 1 during pre-assembly.

Advantageously, it is possible to press the rings of the cassette gaskets together in a preinstalled state. This preinstalled state can be achieved by removing the two rings 3 . 4 by means of a conical installation aid 10 merges so that the radial sealing lip rests securely on its associated sealing surface on the hollow cylindrical part of the second ring. This also ensures that the radial sealing effect is achieved by the radial closing effect 7 prevents falling apart of the two rings by traction during transport.

In summary, the invention relates to a cartridge seals for sealing a radial bearing, wherein the cartridge seal has two relatively movable rings and both rings have a hollow cylindrical portion and a radially extending portion, wherein in the operating state, the hollow cylindrical parts are radially opposite and the radially extending parts axially , The goal is to increase the effectiveness of the gasket while allowing easy installation of the cartridge gaskets. This is achieved in that an outer radius of the radially extending portion of the second ring is greater than the largest inner radius of the hollow cylindrical portion of the first ring and smaller than the outer radius of the hollow cylindrical portion of the first ring. This makes it possible with the same cost of materials to produce a labyrinth seal that protects the interior of the cartridge seals and thus also the rolling space of the radial bearing better against external influences, such as moisture and dirt particles.

LIST OF REFERENCE NUMBERS

1

first bearing part

2

second bearing part

3

second ring

4

first ring

5

elastic part

6

radial sealing lip

7

radial sealing lip

8th

axial sealing lip

9

press tool

10

installation Help

11

radial sealing gap

12

axial sealing gap

13

tail

14

conical press-fit surface

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1898132 A1 [0005]

Claims (10)

A cartridge seal for sealing a radial bearing, wherein the cartridge seal comprises two relatively movable rings ( 3 . 4 ) and both rings ( 3 . 4 ) have a hollow cylindrical part and a radially extending part, wherein in the operating state, the hollow cylindrical parts are radially opposite and the radially extending parts axially, wherein the hollow cylindrical part of the first ring ( 4 ) has a larger outer radius (R _a2 ) with respect to the axis of rotation than any other hollow cylindrical part of the cartridge seal for placement within a bearing part of the radial bearing, characterized in that an outer radius (R _a1 ) of the radially extending part of the second ring (R _a1 ) 3 ) is greater than an inner radius (R _i ) of the hollow cylindrical part of the first ring ( 4 ) and the outer radius (R _a ) of the radially extending part of the second ring ( 3 ) is smaller than the outer radius (R _a2 ) of the hollow cylindrical part of the first ring ( 4 ). A cartridge seal according to claim 1, wherein the first ring ( 4 ) an elastic part ( 5 ) with a radial sealing lip ( 7 ) having. Cassette gasket according to claim 2, wherein the radial sealing lip ( 7 ) on the hollow cylindrical part of the second ring ( 3 ) sealingly. Cassette gasket according to one of the preceding claims, wherein at least one of the two hollow cylindrical parts for fastening the respective ring ( 3 . 4 ) is provided. Cassette gasket according to one of the preceding claims, wherein a radial end piece ( 13 ) of the radially extending part of the second ring ( 3 ) forms a radial gap seal with a bearing ring or a wheel hub. Cassette gasket according to one of the preceding claims, wherein the radial end piece ( 13 ) of the radially extending part of the second ring ( 3 ) with the hollow cylindrical part of the first ring ( 4 ) forms an axial gap seal. Cassette gasket according to one of the preceding claims, wherein the radial end piece ( 13 ) of the radially extending part of the second ring ( 3 ) for axial force transmission to the hollow cylindrical part of the first ring ( 4 ) is provided during the press-in process. A cartridge seal according to any preceding claim, wherein the cartridge seal has a seal labyrinth and the seal labyrinth forms a pre-seal. Installation method of a cartridge seal in a radial bearing, in which a radial sealing lip ( 7 ) from a first ring ( 4 ) of the cassette seal is supported and on a hollow cylindrical part of a second ring ( 3 ) of the cartridge seal during a press-fitting operation sealingly, characterized in that a press-in tool ( 9 ) with a conical axial outer surface ( 14 ) the cassette seal by means of axial force transmission from the second ring ( 3 ) on the first ring ( 4 ). An installation method according to claim 9, wherein the radially extending part of the second ring ( 3 ) by the conical, axial outer surface ( 14 ) is stressed so elastically that the distance required for a sealing effect from the hollow cylindrical part of the first ring to the radially extending part of the second ring ( 3 ).

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