FORM 2
THE PATENT ACT 1970 (39 of 1970)
The Patents Rules, 2003 COMPLETE SPECIFICATION [See Section 10, and rule 13
1. TITLE OF INVENTION
SEALING-OR EXPANSION BELLOWS

2. APPLICANT(S)
a) Name
b) Nationality
c) Address
AND
a) Name
b) Nationality
c) Address

ZF FRIEDRICHSHAFEN AG GERMAN Company 88038 FRIEDRICHSHAFEN, GERMANY
CARL FREUDENBERG KG GERMAN Company 69465 WEINHEIM, GERMANY

3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed : -


The invention relates to sealing- or expansion bellows according to the preamble of claim 1.
Generic sealing bellows are disclosed for example in DE 1 575 684 A. The specification describes sealing bellows for a ball joint of a motor vehicle, which are used to seal two components that are movable relative to one another. Here, the components that are movable relative to one another are a ball pin and a housing, the ball pin being mounted pivotably and rotatably in the housing of the ball joint. The sealing bellows used to seal the components that are movable relative to one another have two mutually spaced-apart edge regions, in which in each case a clamping element is embedded. According to the disclosure of the specification, the embedding of the clamping element may be effected completely or only partially. A first one of the edge regions provided on the sealing bellows lies sealingly against the ball pin, while the opposite, second edge region of the sealing bellows is connected to the housing of the ball joint. Situated between the edge regions of the sealing bellows is a jacket.
With such a solution there may be a restriction of the freedom of motion of the ball pin. The design of the lateral surface and of the fold formed in this region defines the amount of the deflection angle, through which the ball pin is pivotable relative to the housing. If this fold is designed too small, this may lead at the limit values of deflection of the ball pin to a lifting of one of the edge regions of the sealing bellows off the component to be sealed. This would however mean a reduction or termination of the sealing function and is therefore to be avoided. Otherwise, the available angle of deflection of the ball pin is limited. Furthermore, depending on the size of the fold of the jacket such a construction takes up a relatively large amount of installation space.
In order to be able to realize larger angles of deflection, it is known for bellows in the region of their jacket to be equipped in the direction of their axial extent with a plurality of successive folds. With such " multi-fold" bellows it is possible to realize
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larger angles of deflection and hence, on the whole, greater freedoms of motion of the components that are movable relative to one another. WO 2005/121573 A2 discloses a ball joint, in which the sealing bellows in the region of their jacket and in the direction of their axial extent have a plurality of folds. In this construction also, the jacket forms a connection between two edge regions that are formed on the sealing- or expansion bellows. In this known solution the edge regions are however fixed on the respective component in each case by means of a clamping ring that has to be mounted from outside onto the edge region. These clamping rings, which mostly possess very simple elastic properties, have the drawback that their mounting is very laborious. Furthermore, as they often have sharp-edged ends there is a risk of damage to the sealing bellows. Clamping ring fastenings, such as are described in WO 2005/121573 A2, may be used also for the previously described sealing bellows but, in this case too, have the described drawbacks.
The underlying object of the invention is to provide sealing- or expansion bellows, which guarantee a maximum freedom of motion of two components that are movable relative to one another and which are moreover of a simple construction and economical to manufacture. A further object is to indicate a use of such sealing-or expansion bellows.
The invention achieves this object by means of the features of the independent claims. Further developments are indicated in the attached sub-claims.
Sealing- or expansion bellows for sealing two components, which are movable relative to one another, having two mutually spaced-apart edge regions, which are connected by a jacket and in which in each case a clamping element is embedded, are according to the invention developed in such a way that the jacket has a plurality of inside diameters, which differ in their amount, and the inside diameter of one of the edge regions of the sealing- or expansion bellows is greater than the greatest of the inside diameters of the jacket of the sealing- or expansion bellows.
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With the solution according to the invention sealing- or expansion bellows are provided, which enable a high degree of mobility of the components that are movable relative to one another, for the sealing of which the sealing- or expansion bellows are used. By virtue of the clamping elements embedded in the edge regions the previously necessary, very laborious mounting operation for fastening the clamping rings on the edge regions is eliminated. It is moreover also possible thereby to avoid the risk of damage to the sealing- or expansion bellows.
In the case of sealing- or expansion bellows having clamping elements embedded in the edge regions, it was previously necessary to design the geometric configuration in such a way as to enable easy removal from the vulcanizing or injection mould needed for manufacture. To this end, sealing- or expansion bellows have up till now had a circular-cylindrical or conical contour. It is only when these sealing- or expansion bellows are mounted that the fold or outward bulge needed for the freedom of motion of the components that are movable relative to one another is formed as a result of a corresponding compression of the jacket. This procedure however has the drawback that it is impossible to control the formation of the fold. Depending on the given material constellation and wall thickness of the jacket, the outward bulge of the sealing- or expansion bellows develops at any point of their jacket.
This is where the invention comes in, in that the inside diameter of one of the edge regions of the sealing- or expansion bellows is greater than the greatest of the existing inside diameters of the jacket of the sealing- or expansion bellows. This therefore also allows sealing- or expansion bellows that may be manufactured in the form of multi-fold bellows to be removed without difficulty from the vulcanizing or injection mould, and the mandrel disposed in the sealing- or expansion bellows may be removed without leading to damage of the component. The design of the internal shape of the sealing- or expansion bellows according to the invention therefore allows an easy and straightforward removal from the vulcanizing or injection mould. Consequently, by virtue of the features according to the invention the ability
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to manufacture sealing- or expansion bellows is also simplified and improved to a crucial extent.
According to a development of the invention it is moreover advantageous if the jacket of the sealing- or expansion bellows has at least one inside diameter that is smaller than the inside diameters of the jacket that - viewed in axial extent of the sealing- or expansion bellows - are adjacent thereto. The at least one inward bulge between two folds that is thereby formed in the region of the jacket of the sealing- or expansion bellows advantageously allows a considerable freedom of motion of the components that are movable relative to one another and are sealed by means of the sealing- or expansion bellows. As the sealing- or expansion bellows designed in accordance with the invention offer only an extremely low resistance to the components that are movable relative to one another, these components are easily movable.
In order to facilitate the mounting of the sealing- or expansion bellows according to the presently proposed solution on the components that are movable relative to one another, it is advantageous if the clamping elements exhibit an elasticity. For this reason, it is proposed that the clamping elements are spring lock washers. These spring lock washers, which have elastic properties and are embedded in the edge regions of the sealing- or expansion bellows, may be drawn over the relevant components equipped with the sealing- or expansion bellows and position themselves easily and sealingly against the respective surface.
The material stress that is transmitted also to the sealing- or expansion bellows by the movement of the components that are movable relative to one another may lead in the course of the life of such a component to the displacement of at least one of the edge regions of the sealing- or expansion bellows along one of the components. Such a displacement however poses the risk of damage and hence leakages. To avoid this, according to a development of the invention at least part of at least one of the clamping elements projects at the radially inner side of the edge region of the
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sealing- or expansion bellows from said edge region. By means of the projecting part of the clamping element a fixing of the edge region of the sealing- or expansion bellows on the component may be improved. It is thereby possible to prevent an unwanted movement of the sealing- or expansion bellows.
It may moreover be crucially advantageous if at least one of the clamping elements embedded in the edge regions of the sealing- or expansion bellows is of a claw-like design and after mounting of the sealing- or expansion bellows is brought non-positively and/or positively into engagement with the surface of the corresponding component. By virtue of the claw-like design of the relevant clamping element, this clamping element may dig for example into the surface of the corresponding component. This process that occurs once during the mounting of the sealing- or expansion bellows guarantees a secure fixing of the edge region or edge regions of the sealing- or expansion bellows on the corresponding components that are movable relative to one another. It is of course also possible for both edge regions of the sealing- or expansion bellows to have such clamping elements of a claw-like design. The decision for or against such a solution depends upon the material parameters of the corresponding components. Preferably such a claw-like design of the clamping elements will be usable when the corresponding components are manufactured from a softer material than the clamping elements. However, this is not an absolute requirement for the realization of this development. It is equally possible to provide in the corresponding components a groove-shaped recess, into which the component parts of the clamping elements or of the clamping element that are of a claw-like design engage. Thus, a plurality of solutions for securing the edge regions of the sealing- or expansion bellows against an unwanted movement in axial direction lie within this inventive concept.
According to a development of the invention, it is further proposed that the greatest inside diameter of one of the edge regions of the sealing- or expansion bellows corresponds to the inside diameter of one of the clamping elements. Thus, both the relevant edge region and the clamping element embedded in the edge region have
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the same inside diameter. Here, by the inside diameter of the clamping element is meant the portion of this clamping element that lies radially furthest in.
As already mentioned in the introduction, a drawback of the previously known sealing- or expansion bellows, which have clamping elements embedded at both ends in their edge regions, is that the formation of the fold and/or outward bulge of the jacket occurs only as a result of the mounting of the sealing- or expansion bellows and during this process there is no defined formation of the fold. For this reason, it is proposed that the jacket of the sealing- or expansion bellows has - in relation to its axial extent - alternating portions having increased and reduced cross sections. In this case, the essential advantage is that the portions having increased cross sections exhibit a greater stability than the portions having reduced cross sections. Given sealing- or expansion bellows equipped in this way, it is consequently possible to predetermine exactly at which points of the jacket an outward or inward bulge will be formed. These outward or inward bulges namely arise in the regions that have a reduced cross section. Thus, the sealing- or expansion bellows according to the presently proposed solution have a uniform external contour also in the mounted state. This is particularly advantageous because it allows the layout of adjacent components to be effected very precisely and a considerable amount of installation space to be saved.
A continuation of the previously described measures on sealing- or expansion bellows results in the jacket of the sealing- or expansion bellows having a plurality of folds, the flanks of which have in each case an increased cross section.
The sealing- or expansion bellows according to the invention may be used advantageously for a ball joint in particular for installation in a motor vehicle.
There now follows a detailed description of a preferred form of implementation of the invention with reference to the accompanying drawings. The illustrated embodiment does not constitute a restriction to the represented variant but serves
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merely to explain a principle of the invention. In this description, identical components or components of an identical type are denoted by the same reference characters. In order to be able to pictorialize the mode of operation according to the invention, the figures show only extremely simplified schematic representations, from which components that are not central to the invention have been omitted. However, this does not mean that such components are not present in the solution according to the invention. The drawings show:
Figure 1: an axial section through sealing- or expansion bellows according to the invention,
Figure 2: a single-part drawing of a clamping element embedded in one of the edge regions of the sealing- or expansion bellows,
Figure 3; a different clamping element embedded in one of the edge regions of the sealing- or expansion bellows,
Figure 4: a section through an assembly group having sealing- or expansion
bellows according to the invention and
Figure 5: two stages of the manufacture of sealing- or expansion bellows according to the present invention.
Figure 1 shows sealing- or expansion bellows that are represented in axial cross section and denoted as a whole by 8. These have two mutually spaced-apart edge regions 4 and 5. Between the edge regions 4 and 5 the rotationally symmetrical sealing- or expansion bellows 8 have a jacket 3. The sealing- or expansion bellows 8 viewed in their axial extent are characterized by a plurality of successive diameters of differing amounts. The essential point here is that the inside diameter dl of the edge region 5 is greater than the greatest of the remaining diameters 62, d3 and/or

d4 of the jacket 3. The contour of the jacket 3, viewed in cross section, forms an undulating shape, which in terms of the sealing- or expansion bellows 8 means that the bellows in their axial extent have a plurality of successive folds 9 and 10. In this case, portions having an increased cross section alternate in each case with portions having a reduced cross section. The portions having an increased cross section form in each case flanks 11,12,13 and 14. Situated therebetween are the regions having a smaller material cross section. As a result of this, in the case of the represented sealing- or expansion bellows, after their removal from the vulcanizing or injection moulding tool the characteristic folds of the lateral surface 3 are formed without any special action being required for this purpose. A clamping element 6 is vulcanised into the edge region 4 of the sealing- or expansion bellows 8. The vulcanizing process may be used to manufacture such sealing- or expansion bellows since they are manufactured as a whole from an elastic material. This material may in particular be vulcanized rubber that may be produced for example from unvulcanized natural rubber. At the end opposite the edge region 4 an edge region 5 is formed on the sealing- or expansion bellows 8. This edge region 5 accommodates a clamping element 7 that is likewise embedded during the vulcanizing process, i.e. during the manufacture of the sealing- or expansion bellows 8, directly in this edge region 5. The inside diameter dl of this clamping element 7 in this case corresponds to the inside diameter of the edge region 5 and is the greatest inside diameter provided in the region of the lateral surface 3 of the sealing- or expansion bellows 8. By virtue of this special geometric configuration, the mandrel 19 present in the manufacturing tool of the sealing- or expansion bellows 8 may be removed without difficulty without leading to any damage of the sealing- or expansion bellows. The edge region 4 of the represented sealing- or expansion bellows 8 has the characteristic feature that at the inner lateral surface thereof a labyrinth seal is formed. This undulating labyrinth seal improves the seating on the component to be sealed.
Figure 2 shows by way of example as a single-part drawing a perspective view of the clamping element 6 that is embedded in the edge region 4 of the sealing- or
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expansion bellows 8. In the mounted state of the sealing- or expansion bellows 8 the limb of this, in cross section, L-shaped clamping element 6 that extends approximately parallel to the axial extent of the sealing- or expansion bellows 8 follows an approximately parallel course relative to the component sealed by means of the edge region 4.
A further constructional variant of a clamping element for embedding in one of the edge regions of the sealing- or expansion bellows is shown likewise as a single-part drawing and in a perspective view in Figure 3. The characteristic feature of this clamping element 7, which is preferably embedded in the edge region 5 of the sealing- or expansion bellows 8, is that it has numerous recesses 16 distributed over its circumference at the radially inner side of the sealing- or expansion bellows 8. Formed between the recesses 16 are teeth 15. These teeth 15 ensure a secure fixing of the edge region 5 on the corresponding component. Thus, the edge region 5 of the sealing- or expansion bellows 8 is secured in this way against axial drifting. As is evident from the representation of Figure 3 and likewise from the sectional representation of Figure 1, the teeth 15 have an angular alignment relative to the axial longitudinal direction of the sealing- or expansion bellows 8. By virtue of this setting angle the fixing of the edge region 5 on the component to be sealed is crucially improved because an increase of the elasticity of the clamping element 7 is achievable thereby.
Figure 4 shows a section through an assembly group that has sealing- or expansion bellows 8 according to the invention. The illustrated assembly group comprises a first component 1 and a second component 2. The first component 1 is a ball pin of a ball joint, the joint ball of which is mounted rotatably and pivotably inside a housing. The component 2 is this housing and only a suggestion thereof may be seen in Figure 4. Disposed between the pin portion of the ball pin 1 and a seating surface formed for this on the housing 2 are the sealing- or expansion bellows 8. They rest at one end by their edge region 4 and the clamping element 6 embedded therein against the ball pin 1. The opposite edge region 5 with the clamping element
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7 embedded therein rests against the housing 2. In this case, the clamping element 7 is supported resiliency by one of its flanks against the seating surface of the housing 2. Extending between the edge regions 4 and 5 is the jacket 3 of the sealing- or expansion bellows 8. This has a plurality of successive flanks 11, 12, 13 and 14, which jointly form two - viewed in axial extent of the sealing- or expansion bellows - successive folds 9 and 10. The assembly group shown in Figure 4 is represented in a non-deflected state of the ball pin. In this state, the folds are disposed closely adjacent to one another. The labyrinth seal of the edge region 4 of the sealing- or expansion bellows 8 in the presently illustrated embodiment is formed on two sides of the edge region 4 and supported, as already mentioned, on the one hand against the ball pin 1 and on the other hand against a fastening component 20 of the motor vehicle.
In Figure 5 with the aid of a simplified stage plan the manufacture of sealing- or expansion bellows according to the present invention is pictorialized. Thus, the diagram part "a" of Figure 5 shows a closed vulcanizing or injection mould. This comprises a first mould half 17 and a second mould half 18. The parting of the mould extends along the axial longitudinal centre line of the sealing- or expansion bellows 8. A mandrel 19 is inserted in the cavity formed inside the mould halves 17 and 18, thereby leaving between the mandrel 19 and the inner surfaces of the mould halves 17 and 18 a cavity corresponding to the sealing- or expansion bellows 8. Liquefied elastomer, preferably rubber, is injected into this cavity. In order to embed the clamping elements 6 and 7 in the edge regions 4 and 5 of the sealing- or expansion bellows 8 during this vulcanizing process, they are inserted into the vulcanizing or injection mould at appropriate positions before the start of the vulcanizing process. Thus, during the vulcanizing process the sealing- or expansion bellows 8 are already given a shape that corresponds to their final configuration. For removing the finished and cooled sealing- or expansion bellows 8 from the mould, the mould halves 17 and 18 are moved apart from one another at right angles to the axial longitudinal centre line of the sealing- or expansion bellows 8. This processing state is shown in a schematically simplified manner in the diagram part "b" of
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Figure .5. In addition to the separation of the mould halves 17 and 18 from one another, the mandrel 19 is also removed from the interior of the sealing- or expansion bellows 8. The removal of the mandrel 19 is effected in the direction of the arrow A in Figure 5b. This direction corresponds to the direction of the axial longitudinal centre line of the sealing- or expansion bellows 8. The removal of the mandrel 19 is also possible without further difficulty as the inside diameter dl of the edge region 5 and of the clamping element 7 embedded therein is greater than the other diameters d2 to d4 of the jacket 3 of the sealing- or expansion bellows 8.
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List of reference characters

1. first component
2. second component
3. jacket
4. edge region
5. edge region
6. clamping element
7. clamping element
8. sealing- or expansion bellows
9. fold
10. fold
11. flank
12. flank
13. flank
14. flank
15. teeth
16. recesses
17. first mould half
18. second mould half
19. mandrel
20. fastening component of the motor vehicle
dl-d4 inside diameters
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CLAIM:
1. Sealing- or expansion bellows for sealing two components (1, 2) that are movable relative to one another, having two mutually spaced-apart edge regions (4, 5), which are connected by a jacket (3) and into which in each case a clamping element (6, 7) is embedded, characterized in that the jacket (3) has a plurality of inside diameters (d2, d3, d4), which differ in their amounts, and the inside diameter (dl) of one of the edge regions (4, 5) of the sealing- or expansion bellows (8) is greater than the greatest of the inside diameters (d2, d3, d4) of the jacket (3) of the sealing- or expansion bellows (8).
2. Sealing- or expansion bellows according to claim 1, characterized in that the jacket (3) has at least one inside diameter (d3) that is smaller than the inside diameters (d2, d4) of the jacket (3) that - viewed in axial extent of the sealing-or expansion bellows (8) - are adjacent thereto.
3. Sealing- or expansion bellows according to claim 1 or 2, characterized in that the clamping elements (6,7) are spring lock washers.
4. Sealing- or expansion bellows according to one of the previously described claims, characterized in that at least part of at least one of the clamping elements (6, 7) projects at the radially inner side of the edge region (4, 5) of the sealing- or expansion bellows (8) from said edge region (4, 5).
5. Sealing- or expansion bellows according to one of the previously described claims, characterized in that at least one of the clamping elements (6, 7) embedded in the edge regions (4, 5) of the sealing- or expansion bellows (8) is of a claw-like design and after mounting of the sealing- or expansion bellows (8) is brought non-positively and/or positively into engagement with the surface of the corresponding component (1,2).
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6. Sealing- or expansion bellows according to one of the previously described claims, characterized in that the greatest inside diameter (dl) corresponds to the inside diameter of one of the clamping elements (6,7).
7. Sealing- or expansion bellows according to one of the previously described claims, characterized in that the jacket (3) of the sealing- or expansion bellows (8) has in relation to its axial extent alternating portions having increased and reduced cross sections.
8. Sealing- or expansion bellows according to claim 7, characterized in that the jacket (3) of the sealing- or expansion bellows (8) has a plurality of folds (9, 10), the flanks (11, 12, 13, 14) of which have in each case an increased cross section.
9. Ball joint, equipped with sealing- or expansion bellows according to one of the previously described claims.
HIRAL CHANDRAKANT JOSHI
AGENT FOR ZF FRIEDRICHSHAFEN AG and CARL FREUDENBERG KG