Title of Invention

BALL JOINT FOR AN AXLE SYSTEM OF A MOTOR VEHICLE

Abstract

The invention relates to a ball-and-socket joint, for example for an axle system of a motor vehicle. The ball-and-socket joint has a substantially ring- or pot-shaped joint housing (2), wherein the ball (7) of a ball pin (1) is held in the interior space of the joint housing (2) such that it can slide. The ball-and-socket joint is characterised according to the invention in that the joint housing (2) consists of a housing half (4) on the ball pin side and of a housing half (5) on the housing cover side. In this respect the two housing halves (4, 5) have a respective axial stop (9) which extends substantially all round. The housing halves (4, 5) can be brought to lie against one another in an exactly defined manner in the axial direction on account of the axial stop (9).

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 88 038 FRIEDRICHSHAFEN GERMANY 3. PREAMBLE TO THE DESCRIPTION The following specification particularly describes the invention and the manner in which it is to be performed : - Description The invention relates to a ball-and-socket joint, for example for an axle system or a wheel suspension of a motor vehicle, according to the preamble of Claim 1. Ball-and-socket joints of the type initially mentioned are used, for example, although by no means exclusively, on the chassis or in the region of the wheel suspension or steering assembly of motor vehicles - e.g. as a supporting joint or as a guide joint. Generic ball-and-socket joints according to the prior art usually have a one-part housing and a bearing shell disposed therein, in most cases of a polymer material. In order to fix the bearing shell in the housing, an axially end-face region of the housing is in most cases shaped such that the bearing shell and the ball are compressed or enclosed in the joint housing under a certain preload. Other known designs of generic ball-and-socket joints likewise have a one-part joint housing with a two-part bearing shell being disposed in the joint housing, this likewise usually consisting of plastics material. In this case the joint housing is closed and/ or the bearing shell fixed in the housing in a manner similar to that of the known ball-and-socket joints with a one-part bearing shell. However the manufacture of known ball-and-socket joints of this kind entails the problem that, when closing the housing, which generally takes place as described by shaping a sub-region of the joint housing, the position of the ball socket in the joint housing and, in particular, the preloading relationships between the bearing shell and the joint ball cannot be optimally controlled or reproduced. In the case of the known ball-and-socket joints the level of the preloading forces in the ball-and-socket joint - and the functionally important characteristic value, which is connected therewith, of the tilting moment required to move the joint ball in the ball socket - therefore depend essentially on the care taken in the shaping process. The result in the case of the ball-and-socket joints which are known from the prior art is therefore a correspondingly wide variation in the tilting moment values. However tolerances of this kind of the tilting moment values are increasingly no longer accepted, in particular where exacting applications are concerned. Against this background, the object of the present invention is to provide a ball-and-socket joint with which the above-mentioned disadvantages of the prior art can be overcome. The ball-and-socket joint should in particular have the smallest possible tolerances, in a way which can be reliably controlled in manufacturing terms, in particular with regard to the tilting moment. This object is achieved by a ball-and-socket joint having the features of Claim 1. Preferred embodiments constitute the subject matter of the subclaims. The ball-and-socket joint according to the invention in the first place comprises, in a manner known per se, a joint housing with an interior space which in most cases is substantially pot-shaped or cylindrical, with the joint ball of the ball-and-socket joint being held in the interior space of the joint housing such that it can slide. According to the invention, however, the ball-and-socket joint is characterised in that the joint housing - related to the longitudinal axis of the ball pin in its neutral position - consists of a housing half on the ball pin side and of a housing half on the housing cover side. In this respect the two housing halves can be brought to lie against one another in an exactly defined manner in the axial direction of the joint housing by means of a respective stop extending substantially all round in the shape of a ring. In this connection the term "housing halves" is simply intended to mean in the general sense that the joint housing is constructed in two parts in the claimed characteristic manner, the "housing halves" by no means having to be of the same size or shape. In other words, this means that, when assembling the ball-and-socket joint according to the invention, the two housing halves are always relatively positioned absolutely exactly in the axial direction of the joint housing on account of the dimensionally corresponding stops in each case disposed at the two housing halves. However, unlike the prior art, this also ensures that the internal volume of the joint housing will always be exactly the same, which in turn leads to exactly reproducible preloading relationships between the joint housing and the joint ball or between a bearing shell disposed in the joint housing and the joint ball. The housing halves preferably also have a respective radial stop which likewise extends substantially all round. The two dimensionally corresponding radial stops ensure that the housing halves also lie against one another in an exactly defined and centred manner in the radial direction. In this respect, in order to put the invention into effect, it is in the first place of no importance whether the ball-and-socket joint especially also has a bearing shell, from which material and in which style the bearing shell, if applicable, is constructed, or whether a bearing shell which may be provided is configured in one or two parts. However, according to one particularly preferred embodiment, at least one housing half, preferably both housing halves, at the same time in each case directly forms(s) a part of the bearing shell for the joint ball. In other words, this means that one half or both halves of the joint housing - without an especially interposed bearing shell - at the same time represent(s) the bearing surface for the joint ball on its/their inside. In the first place this obviates the necessity of additionally having to provide a separate bearing shell, which already enables expenditure and corresponding costs to be saved. Moreover, further reduced tolerances of the dimensions and, in particular, of the preloading forces and tilting moments, connected therewith, of the ball-and-socket joint can in this way be achieved. Since there is therefore no longer a requirement between the joint ball and the joint housing for an additional bearing shell, which, according to the prior art - also on account of the necessity indicated here of tolerance compensation - in most cases consists of a polymer material with a low load carrying capacity, it is also possible to substantially increase the permissible surface pressure between the metallic pairing of the joint ball and the joint housing. Either an extension of the service life, an increase in the load carrying capacity with the same dimensions, or a reduction of the dimensions and of the weight of the ball-and-socket joint can be derived from this. All this is advantageously to the benefit of an improvement of the cost-benefit ratio of the ball-and-socket joint. The problems frequently occurring in the prior art concerning the correct fixation of the bearing shell in the ball-and-socket joint while at the same time adhering to the designated preloading forces between the bearing shell and the joint ball are also completely eliminated by a ball-and-socket joint in which the housing halves at the same time directly represent the bearing shell. In this respect the housing half forming the bearing shell or the housing halves forming the two bearing shells preferably has/have a surface hardening in the region of its/their contact faces with the joint ball. On account of the surface hardening, which is preferably in the form of an inductive hardening, the permissible surface pressures between the joint housing and the joint ball can be substantially increased even further. The ball-and-socket joint can therefore be further reduced in size with the same load carrying capacity, or the nominal load of the ball-and-socket joint can be increased while the dimensions remain unchanged. In addition, further reduced coefficients of friction, a further reduced variation in the tilting moment of the ball-and-socket joint and a substantial extension of the service of the ball-and-socket joint can in this way be achieved. According to a further, particularly preferred embodiment of the invention, the joint housing interior space has a recess which extends all round in the shape of a ring. A ring element of elastic polymer material is disposed in the all-round recess, the ring element preferably being under a defined preload. This embodiment is advantageous in so far as a particularly exact definition of the desired preload and of the desired friction or tilting moment of the ball-and-socket joint can in this way be achieved. It is equally possible in this way to set exactly specifiable values for the shock or vibration absorption in a ball-and-socket joint, and the ring element can additionally be used as wear compensation for the abrasion of the bearing surfaces of the joint ball or joint housing which is to be expected. The invention is in the first place put into effect irrespective of the constructional manner of connecting the two housing halves, as long as the housing halves are reliably held together under the loads which are to be expected during operation of the ball-and-socket joint. However, according to one preferred embodiment of the invention, the two housing halves have a corresponding pair consisting of an internal thread and an external thread. The two housing halves can in this way be assembled easily, accurately and reliably by means of a screwed connection once the joint ball is disposed in the interior space formed by the two housing halves. In this respect flat faces are preferably disposed on both housing halves, via which faces the torque required for the screwed connection can be transmitted to the housing halves. According to one alternative embodiment of the invention, one of the housing halves has an undercut which extends substantially all round. When the ball-and-socket joint is assembled, the other housing half has a projection which likewise extends substantially all round. The projection of the second housing half then engages positively behind the undercut of the first housing half when the ball-and-socket joint is finally assembled such that the two all-round stops of the housing halves are pressed firmly onto one another. The all-round projection can in this case be produced by means of compression, end rolling or rolling the end face of a housing half. The connection between the two housing halves can in this way be established particularly quickly and therefore inexpensively, while mutual exact positioning of the housing halves is at the same time still guaranteed owing to the stops according to the invention of the two housing halves. According to a further, likewise particularly preferred embodiment, the ball joint is an axial joint. In this case the housing half on the cover side - i.e. the housing half of the joint housing which is remote from the pin opening - is preferably formed integrally with a connecting element. Here the connecting element can in particular, although by no means exclusively, be an integrally formed-on nut thread or an integrally formed-on threaded bolt. The ball-and-socket joint is in this way implemented as an axial joint with a particularly low number of components, which in turn is to the benefit of inexpensive production and assembly as well as reliable operation of the ball-and-socket joint. The invention is illustrated in detail in the following on the basis of drawings which simply represent embodiments and in which: Fig. 1 shows an embodiment of a ball-and-socket joint according to the invention in a schematic, part-sectional representation; Fig. 2 shows a further embodiment of a ball-and-socket joint according to the invention in a representation corresponding to Fig. 1; Fig. 3 shows a third embodiment of a ball-and-socket joint according to the invention in a representation corresponding to Figs. 1 and 2; and Fig. 4 shows a fourth embodiment of a ball-and-socket joint according to the invention in a representation corresponding to Figs. 1 to 3. Fig. 1 shows a first embodiment of a ball-and-socket joint according to the present invention in a schematic, part-sectional representation in longitudinal section. It is in the first place evident that the ball-and-socket joint according to Fig. 1 is an axial joint which has a ball pin 1 and a joint housing 2 and also sealing bellows 3. However here the joint housing 2 is formed in two parts and comprises the two housing halves 4 and 5. The two housing halves 4 and 5 are screwed together by means of a thread 6 and in this way form not just the actual joint housing, but also at the same time the actual bearing surface for the joint ball 7. Exact and reproducible relative positioning of the two housing halves 4 and 5 is guaranteed by a radial stop at 8 and an axial stop or axial centring by means of a fit at 9. The ball-and-socket joint also comprises an elastic ring element 10 which in the embodiment under consideration is made of an elastomer material and is disposed in an all-round ring groove of the housing half 5 under a defined preload. Owing to the ring element 10, the desired preloading of the ball-and-socket joint and the designated friction or tilting moment upon the ball joint moving can be established particularly exactly in terms of construction and with maximum reproducibility. The designated values for shock and vibration absorption of the ball-and-socket joint can also be exactly specified or set in this way, and the ring element can also be used to compensate for the wear on account of the abrasion, which occurs with time, of the bearing surfaces of the joint ball and the joint housing. It is also evident from Fig. 1 that the housing half 5 which is on the right related to the drawing has an integrally formed-on threaded bolt 11 through which the represented axial joint can be reliably connected to adjacent components. Finally, it can be seen that both housing halves 4 and 5 are provided with flat faces 12, 13 which serve to easily and reliably introduce the torque which is required to screw the two housing halves 4 and 5 together when the ball-and-socket joint is assembled. The ball-and-socket joint according to Fig. 2 essentially only differs from the embodiment according to Fig. 1 through the position of the radial stop 8 and the ring groove or ring element 10. Unlike Fig. 1, the radial stop 8 of the ball-and-socket joint according to Fig. 2 is disposed in the axial end region of the housing half 4. The ring groove for receiving the elastic ring element 10, which in the ball-and-socket joint according to Fig. 1 is formed by a recess in the housing half 5, is only produced in the ball-and-socket joint according to Fig. 2 through the interaction of the two housing halves 4 and 5. A further embodiment of a ball-and-socket joint according to the invention, again in the form of an axial joint, is represented in Fig. 3. The essential difference between the embodiments according to Figs. 1 and 2 and the embodiment according to Fig. 3 lies in the fact that in the case of the ball-and-socket joint according to Fig. 3 the two housing halves 4 and 5 are not connected by means of a screwed connection, but rather by plastic deformation of the housing half 4 on the pin side. The deformation, which can be produced, for example, by means of compression or end rolling, takes place in the end-face region of the housing half 4 on the pin side which is marked by the reference number 14. This shaping produces in the region of the end face of the housing half 4 a projection which extends all round in the shape of a ring and which engages positively behind the undercut, likewise extending all round, of the housing half 5 at the reference number 14 such that the two housing halves 4 and 5 are permanently connected together. Both the axial stops 9 and the radial stops or fits 8 of the two housing halves 4 and 5 are in the process pressed firmly onto one another, so that an exactly defined relative position of the two housing halves 4 and 5 is guaranteed. Finally, Fig. 4 shows a fourth embodiment of a ball-and-socket joint according to the invention which is likewise formed as an axial joint. The axial joint according to Fig. 4 corresponds in its essential features to the axial joint according to Fig. 3, although differs from this in that the housing half 4 on the pin side does not embrace the housing half 5 on the cover side at the reference number 14, as in the case of the axial joint according to Fig. 3, but rather the housing half 4 on the pin side is conversely embraced here by the housing half 5 on the cover side. In the case of the axial joint according to Fig. 4 the compression 14 accordingly does not take place by shaping the housing half 4 on the pin side, but rather by shaping the housing half 5 on the cover side, with the latter again directly bearing the threaded bolt 11 for a reliable connection to adjacent components. The ball-and-socket joint according to Fig. 4 can be of a particularly compact and robust construction, with the additional result of constructional simplifications and therefore potential cost savings in particular with regard to the configuration of the fastening groove on the housing side for the sealing bellows 3. As a result, it is therefore clearly shown that the invention provides a ball-and-socket joint which can be controlled particularly easily in manufacturing terms and therefore at the same time inexpensively produced with a consistently high quality. The ball-and-socket joint according to the invention is in addition characterised by a significant potential for increasing the specific load carrying capacity or optionally for reducing the dimensions. The increasing quality requirements of the market can therefore be met by the ball-and-socket joint according to the invention without this entailing any appreciable cost increases in production. The invention therefore contributes in an important way to the qualitative improvement of ball-and-socket joints and demonstrates its potential in particular in the application of ball-and-socket joints in the field of exacting axle and steering systems as well as wheel suspensions on the motor vehicle. List of reference numbers 1 ball pin 2 joint housing 3 sealing bellows 4, 5 housing half 6 thread 7 joint ball 8 radial stop, fit 9 axial stop 10 elastic ring element 11 threaded bolt 12,13 flat faces 14 compression, all-round projection WE CLAIM: 1. Ball-and-socket joint, for example for an axle system of a motor vehicle, the ball-and-socket joint comprising a joint housing (2) which is substantially ring- or pot-shaped and in the interior space of which the ball (7) of a ball pin (1) is held such that it can slide, characterised in that the joint housing (2) consists of a housing half (4) on the ball pin side and of a housing half (5) on the housing cover side, wherein the two housing halves (4, 5) have a respective axial stop (9) which extends substantially all round and through which the two housing halves (4, 5) can be brought to lie against one another in an exactly defined manner in the axial direction of the joint housing. 2. Ball-and-socket joint according to Claim 1, characterised in that the housing halves (4, 5) have a respective radial stop (8) which extends substantially all round and through which the housing halves (4, 5) can be brought to lie against one another in an exactly centred manner in the radial direction. 3. Ball-and-socket joint according to Claim 1 or 2, characterised in that at least one of the housing halves (4, 5) forms a part of the bearing shell for the joint ball (7). 4. Ball-and-socket joint according to Claim 3, characterised in that the housing half (4, 5) forming the bearing shell has a surface hardening in the region of the contact faces with the joint ball (7). 5. Ball-and-socket joint according to any one of Claims 1 to 4, characterised in that the joint housing interior space has a recess which extends all round in the shape of a ring and in which a ring element (10) of elastic polymer material is disposed. 6. Ball-and-socket joint according to Claim 5, characterised in that the ring element (10) is under a defined preload. 7. Ball-and-socket joint according to any one of Claims 1 to 6, characterised in that the housing halves (4, 5) have a corresponding pair consisting of an internal thread (6) and an external thread (6). 8. Ball-and-socket joint according to any one of Claims 1 to 7, characterised in that the housing halves have flat faces (12,13). 9. Ball-and-socket joint according to any one of Claims 1 to 6, characterised in that one of the housing halves (4, 5) has an undercut which extends substantially all round, wherein a dimensionally corresponding projection (14), which extends substantially all round, of the other housing half engages positively behind the undercut. 10. Ball-and-socket joint according to any one of Claims 1 to 9, characterised in that the ball-and-socket joint is an axial joint. 11. Ball-and-socket joint according to Claim 10, characterised in that the housing half (5) on the cover side is formed integrally with a connecting element (11). ABSTRACT The invention relates to a ball-and-socket joint, for example for an axle system of a motor vehicle. The ball-and-socket joint has a substantially ring- or pot-shaped joint housing (2), wherein the ball (7) of a ball pin (1) is held in the interior space of the joint housing (2) such that it can slide. The ball-and-socket joint is characterised according to the invention in that the joint housing (2) consists of a housing half (4) on the ball pin side and of a housing half (5) on the housing cover side. In this respect the two housing halves (4, 5) have a respective axial stop (9) which extends substantially all round. The housing halves (4, 5) can be brought to lie against one another in an exactly defined manner in the axial direction on account of the axial stop (9). The ball-and-socket joint according to the invention can be well controlled with regard to reproducibility of tolerances in manufacture and at the same time produced inexpensively. The invention additionally enables the specific load carrying of the ball-and-socket joint to be increased and/or the dimensions of the ball-and-socket joint to be reduced. To, The Controller of Patents, The Patent Office, Mumbai

Documents:

1986-MUMNP-2007-ABSTRACT(27-2-2012).pdf

1986-MUMNP-2007-ABSTRACT(GRANTED)-(27-3-2012).pdf

1986-mumnp-2007-abstract.doc

1986-mumnp-2007-abstract.pdf

1986-MUMNP-2007-CANCELLED PAGES(19-4-2011).pdf

1986-MUMNP-2007-CANCELLED PAGES(27-2-2012).pdf

1986-MUMNP-2007-CLAIMS(AMENDED)-(19-4-2011).pdf

1986-MUMNP-2007-CLAIMS(AMENDED)-(27-2-2012).pdf

1986-MUMNP-2007-CLAIMS(GRANTED)-(27-3-2012).pdf

1986-MUMNP-2007-CLAIMS(MARKED COPY)-(27-2-2012).pdf

1986-mumnp-2007-claims.doc

1986-mumnp-2007-claims.pdf

1986-MUMNP-2007-CORRESPONDENCE(16-12-2011).pdf

1986-mumnp-2007-correspondence(17-3-2008).pdf

1986-MUMNP-2007-CORRESPONDENCE(22-2-2012).pdf

1986-MUMNP-2007-CORRESPONDENCE(IPO)-(27-3-2012).pdf

1986-mumnp-2007-correspondence-others.pdf

1986-mumnp-2007-correspondence-received.pdf

1986-mumnp-2007-description (complete).pdf

1986-MUMNP-2007-DESCRIPTION(GRANTED)-(27-3-2012).pdf

1986-MUMNP-2007-DRAWING(GRANTED)-(27-3-2012).pdf

1986-mumnp-2007-drawings.pdf

1986-MUMNP-2007-EP DOCUMENT(27-2-2012).pdf

1986-mumnp-2007-form 1(22-2-2008).pdf

1986-MUMNP-2007-FORM 1(27-2-2012).pdf

1986-MUMNP-2007-FORM 2(GRANTED)-(27-3-2012).pdf

1986-MUMNP-2007-FORM 2(TITLE PAGE)-(27-2-2012).pdf

1986-MUMNP-2007-FORM 2(TITLE PAGE)-(GRANTED)-(27-3-2012).pdf

1986-mumnp-2007-form 26(17-3-2008).pdf

1986-MUMNP-2007-FORM 26(22-2-2012).pdf

1986-MUMNP-2007-FORM 26(27-2-2012).pdf

1986-MUMNP-2007-FORM 3(19-4-2011).pdf

1986-mumnp-2007-form-1.pdf

1986-mumnp-2007-form-18.pdf

1986-mumnp-2007-form-2.doc

1986-mumnp-2007-form-2.pdf

1986-mumnp-2007-form-3.pdf

1986-mumnp-2007-form-5.pdf

1986-mumnp-2007-form-pct-ib-301.pdf

1986-mumnp-2007-form-pct-ib-304.pdf

1986-MUMNP-2007-OTHER DOCUMENT(19-4-2011).pdf

1986-MUMNP-2007-PETITION UNDER RULE 137(19-4-2011).pdf

1986-MUMNP-2007-REPLY TO EXAMINATION REPORT(19-4-2011).pdf

1986-MUMNP-2007-REPLY TO EXAMINATION REPORT(27-2-2012).pdf

1986-MUMNP-2007-US DOCUMENT(27-2-2012).pdf

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