Title of Invention

BALL- AND - SOCKET JOINT

Abstract

The invention relates to a ball-and-socket joint. It relates in particular to the special formation of the bearing shell of a ball-and-socket joint of this kind. In order to guarantee high stability of the bearing shell and therefore of the joint on the one hand and in order to reduce the transmitted structure-borne sound from the viewpoint of comfort on the other, it is proposed that the bearing shell be formed with at least two layers and the inner layer be made of metal and the outer layer of a plastics material, for example polyoxymethylene.

Full Text

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 : BALL-AND-SOCKET JOINT 2. APPLICANT(S) a) Name b) Nationality c) Address ZF FRIEDRICHSHAFEN AG GERMAN Company 88038 FRIEDRICHSHAFEN 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 a ball-and-socket joint. It relates in particular to the special formation of the ball socket or bearing shell of a ball-and-socket joint of this kind for reducing sound transmission. Ball-and-socket joints transmit and receive forces from a plurality of directions. They are used in the region of the steering assembly or the track rod, for example, in vehicle construction. Generic ball-and-socket joints consist of a ball pin, that is a pin with a ball formed at an axial end, a bearing shell holding the ball, and a housing holding the bearing shell and parts of the ball pin. The ball of the ball pin slides within the preloaded, permanently lubricated bearing shell, which is protected by the housing against moisture and soiling as well as against the escape of the lubricant. In the above-mentioned application in a motor vehicle the inner faces of the bearing shell holding the ball are in particular subjected to high loads. The bearing shells are therefore as a rule made of metal. However in modern vehicle construction the requirements to be met in terms of comfort are also constantly increasing and in some cases cannot be adequately fulfilled by ball-and-socket joints with a metallic bearing shell. In this respect one disadvantage lies in the fact that structure-borne sound is transmitted from the chassis to the passenger compartment or delivered into the environment to an undesirable degree through ball-and-socket joints with a metal shell. Ball-and-socket joints with a plastics shell have distinct advantages with regard to the transmission of the structure-borne sound. Joints of this kind can in many cases also meet the requirements regarding load carrying capacity when using modern plastics materials. However their disadvantage lies in the fact that their emergency running properties are clearly limited. This means that in the case of a defect or failure of the housing seal of a corresponding ball-and-socket joint, in consequence of which dirt penetrates into the joint or the lubricant escapes from the actual bearing point, i.e. from the interspace of the faces, sliding against one another, of the ball of the ball-and-socket joint and of the bearing shell, the ball and-socket joint will undergo total failure within a short time. A ball-and-socket joint with a non-metallic bearing shell in which the bearing shell is formed with two layers has become known from DE 103 29 804 Al. According to the solution which is represented in the publication, the two layers forming the shell have different modules of elasticity, with the outer layer, remote from the ball, consisting of an elastically resilient material and the inner layer, near the ball, consisting of a material with a wear-resistant surface. However, with the exception of the indication that the bearing shell consists of a non-metallic material, no more specific details regarding the materials of the two layers forming the bearing shell are given. It is therefore assumed, from the manufacturing viewpoint, that both layers consist of a plastics material, although the plastics materials have different E-modules and surface strengths, as layers of this kind of a different plastics material can be produced in a two-stage injection moulding process and joined together in a favourable manner. The requirement for a reduction of the transmitted structure-borne sound is obviously met here. It is also undoubtedly possible for many purposes to fulfil the requirements regarding the wear resistance when using a corresponding plastics material for the inner layer. However this solution also entails the problem of insufficient emergency running properties. For, unlike metal, plastics materials and comparable materials tend to allow any dirt, as is to be noted, for example, when leakages of ball-and-socket joints occur in the region of the running faces, to bury into the material surface, so to speak. In any case, in this respect metals have emergency running properties which can hardly be achieved by plastics materials. The object of the invention is therefore to provide a ball-and-socket joint which on the one hand meets the increasing requirements in terms of comfort, in particular in terms of a reduction of the structure-borne sound transmission, and on the other, in addition to a high load carrying capacity with regard to the forces introduced into the joint, has good emergency running properties. The object is achieved by a ball-and-socket joint having the features of the main claim. Advantageous formations or developments are given in the subclaims. The ball-and-socket joint which is proposed to achieve the object essentially consists, in a manner known per se, of a joint housing which is open on one side, a joint pin with a joint ball formed at one end, and a spherical bearing shell which is likewise open on one side. The joint ball of the joint pin is held by the joint housing, and the bearing shell, which is permanently lubricated at its inner face, is disposed between the joint ball and the joint housing, whereby a slide face for the joint ball is formed. In the region of the transition between the joint ball and the shank, projecting out of the joint housing, of the joint pin the joint housing is closed by a locking ring and sealed by sealing bellows in order to prevent dirt from penetrating and the lubricant from escaping. The bearing shell is formed with at least two layers, and, according to the invention, the inner layer of the bearing shell consists of metal and its outer layer of a plastics material. This formation results in high wear resistance of the ball-and-socket joint, which, moreover, has good emergency running properties on account of the metallic inner face of its bearing shell. On the other hand, a distinct reduction of the structure-borne sound transmission when compared with ball-and-socket joints with a purely metallic bearing shell is achieved through the outer plastics layer of the bearing shell. If the bearing shell of the ball-and-socket joint according to the invention is formed with two layers, as preferred, the outer, damping plastics layer, which serves to isolate sound, is preferably moulded onto its metallic inner layer. However it is also conceivable for the inner metallic layer and the outer layer consisting of plastics material to be joined together by an adhesive joint. According to a particularly advantageous development of the invention, the bearing shell is formed in two parts. In this respect the two parts, in each case having two or multiple layers, of the bearing shell are joined together via a web acting as a hinge. This type of formation simplifies the assembly of the ball-and-socket joint, i.e. the process of fitting its components together. The joint ball can in this case easily be inserted in the bearing shell, even given a thick metallic cover between the joint housing and the joint ball, as is desirable and implemented in this embodiment. For this purpose this is folded back, as it were, and closed following the insertion of the joint ball. The increased metallic cover results in a higher pull-out strength for the joint pin, so that a higher tensile load of the joints is possible. The bearing shell, open on one side, is preferably divided into two axially symmetrical halves. According to a practice-adapted embodiment, these are formed by two deep-drawn, metallic half-shells which are covered by a plastics layer at their outer circumference and joined together by a web. Here the edges of the half-shells lying against one another inside the joint housing form a circular opening at the open side of the bearing shell, while the axis of symmetry dividing the bearing shell extends perpendicularly through the diameter of this circular opening. In a development of the ball-and-socket joint according to the invention which is likewise of advantage a collar-type web is disposed parallel to the opening edge of the bearing shell, this extending all round its circumference. The bearing shell disposed in the joint housing is fixed in the joint housing and secured against twisting by this collar-type web. The inner metallic layer of the bearing shell preferably has at its surface, which faces the joint ball, at least one groove which forms a reservoir for a lubricant. In order to further increase the wear resistance, the surface of the inner metallic layer of the bearing shell facing the joint ball is chrome-plated or additionally hardened. A QP treatment, i.e. nitriding the metallic inner face of the bearing shell, also advantageously leads to an improvement of the wear resistance. Polyoxymethylene (POM) or polyamide (PA) or polyether ether ketone (PPEK), for example, are possible plastics materials for the outer layer of the bearing shell of the ball-and-socket joint formed in the manner according to the invention. The invention shall be illustrated again in detail in the following on the basis of an embodiment. In the accompanying drawings: Fig. 1 shows a ball-and-socket joint configured according to the invention in an axial semi-section Fig. 2 is an isometric representation of the bearing shell of the ball-and-socket joint according to Fig. 1. Figure 1 shows a possible embodiment of a ball-and-socket joint configured in a manner according to the invention in a semi-section. The ball-and-socket joint consists essentially of the joint pin 4, 5, the bearing shell 1,1', the joint housing 6 and sealing bellows 7. The joint ball 4 of the joint pin 4, 5 is held by the joint housing 6, which is open on one side. The permanently lubricated and spherically shaped bearing shell 1,1' which is likewise open on one side, is disposed between the joint housing 6 and the joint ball 4, the inner face of which shell forms the slide face for the joint ball of the joint pin. The bearing shell 1,1' is constructed with two layers. According to the invention, here the inner layer 2 consists of metal, while the outer layer 3 consists of a plastics material. High stability of the ball-and-socket joint is guaranteed by the metallic inner layer 2 of the bearing shell 1, 1'. As compared with ball-and-socket joints whose bearing shell consists solely of non-metallic materials, i.e. as a rule plastics material, the ball-and-socket joint configured in a manner according to the invention additionally has improved emergency running properties due to the metallic inner face of its bearing shell 1, 1'. Possible leakages of the sealing bellows, in consequence of which dirt penetrates into the joint or the lubricant escapes from its bearing point, do not thereby cause rapid destruction of the ball-and-socket joint, unlike the case of ball-and-socket joints with a plastics bearing shell. The risk of particles of dirt burying into the running face of the bearing shell 1, V is reduced when compared with bearing shells of plastics material. In the embodiment which is shown in Fig. 1 the bearing shell 1, 1' is formed in two parts. It consists of two axially symmetrical halves, which are joined together by a joining web 8 acting as a hinge. The assembly of the ball-and-socket joint is as a result simplified. Moreover, a collar-type web 11 is formed in the lower region of the bearing shell 1, 1, this extending all round its circumference and being compressed between the locking ring 13 and the joint housing 6. The bearing shell 1,1' is fixed in the joint housing 6 when assembly takes place and therefore secured against undesirable twisting when the ball-and-socket joint is used as specified by the collar-type web 11 disposed parallel to the opening edge 9, 9' of the bearing shell. The surface of the inner metallic layer 2 of the bearing shell 1,1' is hardened or QP-treated, i.e. nitrided, for example, in order to further increase its wear resistance. Its outer layer 3 consists, for example, of POM (polyoxymethylene). Due to the elasticity of this material, the vibrations, in particular the structure-borne sound, transmitted from the joint pin 4, 5 via the bearing shell 1, 1' to the joint housing 6 are advantageously damped. On account of the formation according to the invention of the bearing shell 1, 1', the ball-and-socket joint therefore excellently combines the fulfilment of the requirements in terms of its load carrying capacity with the realisation of the requirements existing with regard to comfort. The outer layer 3, consisting of plastics material, of the bearing shell 1, 1' is preferably moulded onto the inner metallic layer 2. However first tests have shown that it could also be possible to glue the outer layer 3 to the inner layer. Fig. 2 shows the bearing shell 1, 1 formed in a manner according to the invention in a two-part formation, again in an isometric representation. As can be seen, both half-shells are formed with two layers and joined together via the web 8, which acts as a hinge. Also to be seen in the representation is the collar-type web 11, already discussed, which extends all round the circumference of the bearing shell. It is also evident that a groove 12 is worked into the metallic inner face of the bearing shell 1, 1'. A grease reserve for the permanent lubrication of the joint is formed through this groove 12. List of reference numbers 1,1' bearing shell 2, 2' inner (metallic) layer 3, 3' outer layer (of plastics material) 4, 5 joint pin 4 joint ball 5 shank of joint pin 6 joint housing 7 sealing bellows 8 web, joining web 9, 9' edge, opening edge 10 opening 11 collar-type web 12 groove, lubricant reservoir 13 locking ring Translator's notes: 1. The word "starken" in the third paragraph on page 4 has been translated as "thick". However this word has several meanings, including "strong", "solid", etc. 2. The word "Bundsteg" occurring in the description and the Claims (ref. no. 11) could not be traced and has therefore been translated literally as "collar-type web". WE CLAIM: 1. Ball-and-socket joint, consisting of a joint housing (6) which is open on one side, a joint pin (4, 5), the joint ball (4) of which, formed at one of its ends, is held by the joint housing (6), a substantially spherical bearing shell (1, 1') which is disposed between the joint housing (6) and the joint ball (4), is likewise open on one side and has a permanently lubricated inner wall as well as a locking ring (13) and sealing bellows (7) which close and seal the open side of the joint housing (6), in the region of the transition between the joint ball (4) and the shank (5), projecting out of the joint housing, of the joint pin (4, 5), wherein the bearing shell (1, 1') is formed with at least two layers, characterised in that the inner layer (2, 2') of the bearing shell (1,1') consists of metal and its outer layer (3, 3') of a plastics material. 2. Ball-and-socket joint according to Claim 1, characterised in that the bearing shell (1, 1') is formed with two layers, wherein the inner metallic layer (2, 2') and the outer layer (3, 3'), consisting of plastics material, are joined together by an adhesive joint. 3. Ball-and-socket joint according to Claim 1 or 2, characterised in that the bearing shell (1, 1') is formed in two parts, wherein thee two parts, in each case having two or multiple layers, of the bearing shell (1, 1') are joined together via a web (8) acting as a hinge. 4. Ball-and-socket joint according to Claim 3, characterised in that the bearing shell (1, 1'), open on one side, is divided into two axially symmetrical halves which are formed by two deep-drawn, metallic half-shells which are covered by a plastics layer at their outer circumference and joined together by a web (8), wherein the edges (9, 9') of the half-shells lying against one another inside the joint housing (6) enclose a circular opening (10) at the open side of the bearing shell (1,1') and the axis of symmetry (y) dividing the bearing shell (1, 1') extends perpendicularly through the diameter of this circular opening (10). 5. Ball-and-socket joint according to any one of Claims 1 to 4, characterised in that a collar-type web (11) is disposed parallel to the opening edge (9, 9') of the bearing shell (1, V), this extending all round its circumference, through which web a fixation and an anti-twist mechanism is formed for the bearing shell (1,1') disposed in the joint housing (6), wherein the collar-type web (11) is compressed between the locking ring (13) and the joint housing (6). 6. Ball-and-socket joint according to any one of Claims 1 to 5, characterised in that the inner metallic layer (2, 2') of the bearing shell (1,1') has at its surface, which faces the joint ball, at least one groove (12) which forms a reservoir for a lubricant. 7. Ball-and-socket joint according to any one of Claims 1 to 6, characterised in that the surface of the inner metallic layer (2, 2') of the bearing shell (1, 1') facing the joint ball (4) is chrome-plated in order to increase its wear resistance. 8. Ball-and-socket joint according to any one of Claims 1 to 6, characterised in that the surface of the inner metallic layer (2, 2') of the bearing shell (1, 1') facing the joint ball (4) is hardened in order to increase its wear resistance. 9. Ball-and-socket joint according to any one of Claims 1 to 6, characterised in that the surface of the inner metallic layer (2, 2') of the bearing shell (1, 1') facing the joint ball (4) is nitrided in order to increase its 10. Ball-and-socket joint according to any one of Claims 1 to 9, characterised in that the outer layer (3, 3') of the bearing shell (1, 1') consists of polyoxymethylene. 11. Ball-and-socket joint according to any one of Claims 1 to 9, characterised in that the outer layer (3, 3') of the bearing shell (1,1') consists of polyamide. 12. Ball-and-socket joint according to any one of Claims 1 to 9, characterised in that the outer layer (3, 3') of the bearing shell (1,1') consists of polyether ether ketone. Dated this 10th day of December 2007. ABSTRACT The invention relates to a ball-and-socket joint. It relates in particular to the special formation of the bearing shell of a ball-and-socket joint of this kind. In order to guarantee high stability of the bearing shell and therefore of the joint on the one hand and in order to reduce the transmitted structure-borne sound from the viewpoint of comfort on the other, it is proposed that the bearing shell be formed with at least two layers and the inner layer be made of metal and the outer layer of a plastics material, for example polyoxymethylene.

Documents:

2099-MUMNP-2007-ABSTRACT(16-10-2012).pdf

2099-MUMNP-2007-ABSTRACT(25-11-2011).pdf

2099-mumnp-2007-abstract.doc

2099-mumnp-2007-abstract.pdf

2099-MUMNP-2007-CANCELLED PAGE(25-11-2011).pdf

2099-MUMNP-2007-CLAIMS(AMENDED)-(16-10-2012).pdf

2099-MUMNP-2007-CLAIMS(AMENDED)-(25-11-2011).pdf

2099-MUMNP-2007-CLAIMS(MARKED COPY)-(16-10-2012).pdf

2099-mumnp-2007-claims.doc

2099-mumnp-2007-claims.pdf

2099-MUMNP-2007-CORRESPONDENCE(10-9-2012).pdf

2099-MUMNP-2007-CORRESPONDENCE(25-11-2011).pdf

2099-mumnp-2007-correspondence(26-2-2008).pdf

2099-MUMNP-2007-CORRESPONDENCE(4-5-2012).pdf

2099-MUMNP-2007-CORRESPONDENCE(5-7-2012).pdf

2099-mumnp-2007-correspondence-others.pdf

2099-mumnp-2007-correspondence-received.pdf

2099-mumnp-2007-description (complete).pdf

2099-MUMNP-2007-DRAWING(25-11-2011).pdf

2099-mumnp-2007-drawings.pdf

2099-MUMNP-2007-ENGLISH TRANSLATION(16-10-2012).pdf

2099-mumnp-2007-form 1(14-2-2008).pdf

2099-MUMNP-2007-FORM 26(16-10-2012).pdf

2099-mumnp-2007-form 26(26-2-2008).pdf

2099-MUMNP-2007-FORM 3(25-11-2011).pdf

2099-MUMNP-2007-FORM 5(25-11-2011).pdf

2099-mumnp-2007-form-1.pdf

2099-mumnp-2007-form-18.pdf

2099-mumnp-2007-form-2.doc

2099-mumnp-2007-form-2.pdf

2099-mumnp-2007-form-3.pdf

2099-mumnp-2007-form-5.pdf

2099-mumnp-2007-form-pct-ib-301.pdf

2099-mumnp-2007-form-pct-ib-304.pdf

2099-MUMNP-2007-FORM-PCT-ISA-237(16-10-2012).pdf

2099-MUMNP-2007-OTHER DOCUMENT(16-10-2012).pdf

2099-mumnp-2007-pct-search report.pdf

2099-MUMNP-2007-PETITION UNDER RULE-137(25-11-2011).pdf

2099-MUMNP-2007-REPLY TO EXAMINATION REPORT(25-11-2011).pdf

2099-MUMNP-2007-REPLY TO HEARING(16-10-2012).pdf

2099-MUMNP-2007-SPECIFICATION(AMENDED)-(16-10-2012).pdf

2099-MUMNP-2007-US DOCUMENT(25-11-2011).pdf

2099-mumnp-2007-wo international publication report(26-2-2008).pdf

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