AU2006249072A1

AU2006249072A1 - Ball-shaped coupling comprising a sealed contact area

Info

Publication number: AU2006249072A1
Application number: AU2006249072A
Authority: AU
Inventors: Udo Szczepanek
Original assignee: Jost Werke SE
Current assignee: Jost Werke SE
Priority date: 2005-05-18
Filing date: 2006-05-18
Publication date: 2006-11-23
Anticipated expiration: 2026-05-18
Also published as: PL1888354T3; WO2006122807A1; CN101208210B; ES2352077T3; CN101208210A; EP1888354A1; EP1888354B1; ATE484404T1; DE502006008088D1; DK1888354T3; UA90512C2; ZA200710985B; AU2006249072B2; DE102005022879A1

Abstract

Disclosed is a ball-shaped coupling (10) for coupling a tractor to a trailer. Said ball-shaped coupling (10) comprises a coupling ball (12) and a ball socket (16) that can be coupled thereto. The ball socket (16) surrounds a section of the coupling ball (12) and rests against a contact surface (24) of the coupling ball (12) by means of an opposite contact surface (22) in the coupled state so as to form a common contact area (28). According to the invention, a seal (38) which seals the contact area (28) towards the environment is provided between the coupling ball (12) and the ball socket (16).

Description

IN THE MATTER OF an Australian Application corresponding to PCT Application PCT/EP2006/004727 RWS Group Ltd, of Europa House, Marsham Way, Gerrards Cross, Buckinghamshire, England, hereby solemnly and sincerely declares that, to the best of its knowledge and belief, the following document, prepared by one of its translators competent in the art and conversant with the English and German languages, is a true and correct translation of the PCT Application filed under No. PCT/EP2006/004727. Date: 13 November 2007 C. E. SITCH Managing Director - UK Translation Division For and on behalf of RWS Group Ltd Wo 2006/122807 - 1 - PCT/EP2006/004727 BALL-SHAPED COUPLING WITH A SEALED BEARING AREA Description 5 The present invention relates to a ball-shaped coupling for coupling a towing vehicle to a trailer, which ball shaped coupling comprises a coupling ball and a ball socket which can be coupled thereto and, in the coupled state, surrounds a section of the coupling ball and 10 bears with an opposed bearing face against a bearing face of the coupling ball so as to form a common bearing area. Ball-shaped couplings of the generic type are known, 15 for example, from DE 201 16 970 Ul. This document discloses, in particular, introducing lubricant into the bearing area in which the bearing face of the coupling ball and the opposed bearing face of the ball socket are in bearing engagement with one another, in 20 order to reduce the wear on the components of the ball shaped coupling. A disadvantage with the known ball-shaped coupling is that, owing to external influences such as thrown up 25 dirt, spray water and the like given the relative mobility of the ball socket and coupling ball it is possible for soiling to undesirably penetrate the bearing area and therefore adversely affect the lubrication film which is formed there, or even destroy 30 it, which can in turn bring about increased wear on the ball-shaped coupling. The object of the present invention is therefore to specify a ball-shaped coupling which, compared to the 35 prior art, allows a higher level of operational reliability and a higher degree of durability to be expected.

-2 This object is achieved according to the invention by means of a ball-shaped coupling of the type mentioned at the beginning in which a seal, which seals off the bearing area from the surroundings, is provided between 5 the coupling ball and the ball socket. "Bearing area" refers here to that area in which the opposed bearing face of the ball socket and the bearing face of the coupling ball are in bearing engagement 10 with one another. The bearing area is therefore locally variable when there is a relative movement of the ball socket and coupling ball. Wherever it is stated in this application that the bearing area is sealed off from the surroundings this is intended to include not only 15 the case of a hermetic and complete seal but also, in accordance with the solution, also to cover the case in which the bearing area is protected against the ingress of spray water and coarse dirt. The seal within the sense of the present invention can, but does not have 20 to, also prevent lubricant from escaping from the bearing area into the surroundings or any fluid from the surroundings entering the bearing area. According to the invention it is sufficient if the seal is able to prevent dirt, spray water and the like from entering 25 the bearing area to an appreciable degree. Since the coupling ball has a surface which is convex, spherical over wide sections, and since the ball socket generally has a concave, part spherical shape at least 30 in the region of its opposed bearing face, the bearing area can be protected particularly easily and reliably against the undesired ingress of dirt if the seal extends along a circular path so that its bearing location against one of the components of the coupling 35 ball or ball socket is a part annular sealing path. If, in fact, the bearing location of the seal against one of the aforesaid components lies in a plane, in the case of the spherical or concave, part spherical -3 surface any sectional line of this surface with the plane is a circle so that a part annular bearing location of the seal against the respective component can protect a large part of the bearing area against 5 the undesired ingress of dirt. Although it is possible to provide in embodiments that the seal runs only along a part circle, for example if in a certain area of the ball-shaped coupling it is not 10 to be expected that dirt will pass from this area to the ball-shaped coupling, it is preferred to protect the bearing area as completely as possible against the undesired ingress of dirt from the surroundings through a circumferential seal with a sealing path which is 15 continuous in an annular shape. If the sealing path is a planar one, an infinitely thin plane in the mathematical sense is not meant by this. Instead, the plane in which the seal is located should 20 have a certain thickness so that the bearing location, i.e. the previously mentioned sealing path, can have a certain thickness too. Within the sense of the present application, any sealing path in which the seal bears against at least one location on the respective 25 component at any desired angular coordinate when viewed from a polar coordinate origin which is covered by the sealing path will be considered to be continuous in an annular shape. This means that the sealing path itself can be formed from a plurality of sealing path sections 30 which are not connected, and it can nevertheless be considered to be continuous in an annular shape in the sense of this application if the separate sealing path sections overlap one another in the circumferential direction or at least abut one another. 35 So that the seal does not impede the bearing engagement between the bearing face and the opposed bearing face and can nevertheless carry out its function of -4 protecting the bearing area as well as possible, it is advantageous if the diameter of the sealing path is smaller than the largest diameter of the coupling ball. 5 For a good sealing effect without any impairment of the bearing engagement of the bearing face and opposed bearing face it is advantageous, in the case of a more detailed structural embodiment if in the coupled state, a section which is parallel to the sealing path, of the 10 coupling ball is located between the seal and the bearing area and has a larger diameter than the diameter of the sealing path. In this case, specifically the sealing path can seal off from the larger diameter of the coupling ball so that, starting 15 from a reference coupled state with a train which is composed of a towing vehicle and a trailer stationary on a planar underlying surface, the contact pressure of the seal against, for example, the coupling ball is only increased, but not reduced, when there is a 20 relative movement between the coupling ball and ball socket. This ensures a minimum bearing pressure of the seal against the coupling ball. According to a less preferred embodiment of the 25 invention, it is possible to consider providing the seal on the coupling ball with a sealing location which points radially outward so that if the ball socket is placed in bearing engagement with the coupling ball, the seal which is provided on the coupling ball also 30 bears with its sealing location against a face of the ball socket and thus seals off the bearing area within the sense of the present application. However, since the ball socket and coupling ball carry out relative movements in the tractive mode, the ball socket may at 35 least in certain sections temporarily move out of bearing engagement with the seal which is provided on the coupling ball, in particular when there are - 5 relatively large pitching or rolling movements of the ball socket in relation to the coupling ball. Since the coupling ball has a significantly larger 5 spherical and thus symmetrical surface of any desired type, compared to the opposed bearing face of the ball socket, it is preferred in order to avoid a spatial and/or chronological disruption of the bearing engagement, at least in certain sections, if the seal 10 is secured to the ball socket and can be moved with it in relation to the coupling ball. Owing to the abovementioned large ball surface of the coupling ball, the seal which is provided at the ball socket with a radially inwardly pointing sealing location and which 15 bears against the surface of the coupling ball remains in fact in bearing engagement with the spherical surface of the coupling ball even when there are pitching and rolling movements of the ball socket in relation to the coupling ball. 20 When the seal is arranged in the ball socket, the sealing path is defined by the seal bearing against the surface of the coupling ball. In this context, a particularly good sealing effect can be achieved if the 25 seal bears against an area of the coupling ball in such a way that at least for a section of the sealing path, preferably for the entire sealing path, a surface normal vector, starting from the sealing path, of the coupling ball surface has a component which is directed 30 in the opposite direction from a respective lifting off direction of the ball socket from the coupling ball. "Lifting off direction" refers here to the direction in which the ball socket would be able to be lifted off 35 from the coupling ball in the respectively considered position of the ball socket in relation to the coupling ball. The lifting off direction is therefore a direction which is securely coupled to the ball socket - 6 and which can be changed in terms of location in relation to the coupling ball. In order to the provide the seal according to the 5 above-described, advantageous development of the present invention on the ball socket, it is advantageous if said seal has a sufficient degree of elasticity so that when the ball socket is fitted onto the coupling ball the seal can be slipped over the 10 largest diameter of the coupling ball so that when the ball-shaped coupling is considered in the reference coupled state defined above with a train composed of a towing vehicle and trailer stationary on a level underlying surface said seal bears, in relation to a 15 largest diameter of the coupling ball parallel to the underlying surface, against a side of the coupling ball which is closer to the underlying surface, while the bearing area which is to be protected by the seal lies on a side of the coupling ball which is more remote 20 from the underlying surface. This property can be implemented satisfactorily by the seal if it has a sealing lip which can be moved in the radial direction. For example, according to one 25 preferred development of the present invention the sealing lip can project from a sealing main body in such a way that, considered in a cross section, it can be moved in the radial direction by bending about a bending axis which is orthogonal with respect to the 30 cross-sectional plane. Attention is expressly drawn to the fact that according to one simplified development of the present invention, a simple 0-sealing ring can also be used as the seal. 35 However, compared to the preferred, radially movable sealing lip, said 0-sealing ring experiences greater deformation, and is therefore continuously stressed to a greater extent, in the coupled state.

- 7 As a rule, the ball socket comprises an essentially concave, part spherical opposed bearing face and also an insertion section which is located between the mouth 5 of the ball socket and the opposed bearing face. The arrangement of the seal on the ball socket is then preferably provided in such a way that the seal is arranged in the insertion section in order to avoid disruption to the bearing engagement between the ball 10 socket and the coupling ball. In order to accommodate the seal, a preferably circumferential groove can be formed in the insertion section in the ball socket. The groove can be 15 fabricated, for example, in the form of an indent. The seal can be inserted very easily into this groove, said seal being preferably surrounded on three sides in the inserted state so that both its radial and its axial position are well defined. 20 Since the seal is subjected to mechanical loading, measures should be taken to ensure that it can be quickly replaced when necessary. According to one embodiment, this can be done by means of the above 25 described circumferential groove. According to an alternative, or possibly additional, embodiment this can also be done by virtue of the fact that the seal comprises a seal carrier which is separated from the coupling ball and the ball socket, the seal carrier 30 being attached with fastening means to one of the components: coupling ball and ball socket. In this context, in order to achieve the abovementioned advantages of reliable sealing of the bearing area it 35 is possible to provide that the seal is attached to the mouth of the ball socket in a releasable fashion.

- 8 In a preferred structural embodiment, a secure attachment of the seal to the ball socket can be ensured, for example, by the seal carrier being formed from metal, having a seal main body which is connected 5 thereto, preferably by vulcanizing on. In order to permanently lubricate the bearing area during operation of the ball-shaped coupling it is possible to provide that the opposed bearing face has 10 at least one lubricant pocket in which the surface areas of the bearing face and opposed bearing face are arranged in the coupled state at a radial distance from one another such that lubricant can be stored between these surface areas. Such lubricant pockets are already 15 known from DE 201 16 970 Ul, to the entirety of whose disclosure reference is made here in relation to the lubricant pockets, and said disclosure is fully incorporated into the present application. 20 In order to simply supply the bearing area with lubricant, it is also possible to provide that in the coupled state the opposed bearing face can be supplied with lubricant from the outside through a lubricant line. For this purpose, the lubricant line can comprise 25 a lubrication nipple which is provided on the ball socket. The present invention will be described in more detail below with reference to the appended drawings. In said 30 drawings: figure 1 shows a cross section through a first embodiment of a ball-shaped coupling according to the invention in the coupled 35 state, and -9 figure 2 shows a cross section, corresponding to the view in figure 1, through a second embodiment of a coupling according to the invention. 5 In the appended figure 1, a ball-shaped coupling according to the invention is denoted generally by 10. The ball-shaped coupling 10 comprises a coupling ball 12 which is usually connected to a towing vehicle (not illustrated), and a ball socket 16 which is usually 10 connected to the tow bar 14 of a trailer (not illustrated). The ball socket 16 has an essentially concave recess 20 starting from a mouth 18. The recess 20 comprises an 15 insertion section 20a which is located closer to the mouth 18 and a concave, part spherical coupling section 20b which adjoins the insertion section 20a. The concave, part spherical coupling section 20b has an essentially part spherical, concave opposed bearing 20 face 22 with which the part spherical, convex surface 23 of the coupling ball enters into bearing engagement in the coupled state of the ball-shaped coupling 10. The concave, part spherical opposed bearing face 22 of 25 the ball socket 16 is embodied so as to be rotationally symmetrical with respect to a rotational axis R. In the example shown in figure 1, in the coupled state and when there is a train which is composed of a towing 30 vehicle and trailer stationary on an level underlying surface U, the rotational axis R is oriented orthogonally with respect to the underlying surface U. Furthermore, in figure 1, a great circle, parallel to 35 the underlying surface U, of the coupling ball 12 is denoted by 26. The bearing area 28, at which the opposed bearing face 22 of the ball socket 16 bears against the bearing face 24 of the coupling ball 12 in - 10 figure 1, is located, in the example shown in figure 1, on the side facing away from the underlying surface U of the coupling ball 12 with respect to the great circle 26 which is parallel to the underlying surface, 5 extends to close to the great circle 26 which is parallel to the underlying surface. The boundary of the bearing area 28 toward the underlying surface U is marked by the dashed line 29. When there is a relative movement between the ball socket 16 and coupling ball 10 12, the bearing area 28 also moves with the ball socket 16. In the coupled state shown in figure 1, the center point M of the coupling ball 12 and the center point m 15 of the spherical opposed bearing face 22 of the ball socket 16 ideally coincide so that forces that act with a translatory effect between the coupling ball 12 and the ball socket 16 can be transmitted in at least two spatial directions, but cannot transmit any torques. 20 In the opposed bearing face 22 of the ball socket 16, what are referred to as lubricant pockets 30 and 32 are formed, in which lubricant pockets 30 and 32 there is a distance between the surface of the ball socket recess 25 20 and the surface 23 of the coupling ball 12 so that a coherent cavity 34, to which the lubricant pockets 30 and 32 belong, can be supplied with lubricant from the outside through a lubricant line 36 by means of a lubricating nipple (not illustrated) which can be 30 screwed into the lubricant line 36. A seal 38 which runs around in the circumferential direction is provided in the insertion section 20a of the ball socket in the direction of the axis R of 35 symmetry at an axial distance. A sealing lip 40 which is also circumferential bears against the coupling ball 12 along an annular, continuous sealing path 42.

- 11 The diameter of the sealing path 42 is smaller than the diameter of the great circle 26. In the illustration in figure 1, the sealing path 42 in the defined reference position is parallel to the underlying surface U, as is 5 the great circle 26. The sealing lip 40 projects from the seal main body 44, which is also circumferential, in such a way that when it is considered in the cross section in figure 1, it 10 can be bent away from the axis R of symmetry, and toward said axis R of symmetry in the radial direction about a bending axis 46 which is orthogonal with respect to the plane of the drawing and the plane of the cross section in figure 1. Compared to the non 15 stressed state of the sealing lip 40, in the coupled state in figure 1 said sealing lip 40 is moved elastically outward in the radial direction by the coupling ball 12 so that the sealing lip 40 bears securely against the surface 23 of the coupling ball 12 20 by virtue of this elastic prestress. By virtue of the sealing lip 40 which is configured in this way, the ball socket 16 can very easily be fitted onto the coupling ball 12 with the seal 38 and lifted 25 off from it. The seal 38 is only slightly stressed mechanically by virtue of the deformability of the sealing lip 40, so that a high service life can be expected. 30 The lifting off direction A of the ball socket 16 is shown in figure 1. It extends away from the coupling ball 12 in the direction of the axis R of symmetry. The lifting off direction A is locationally fixed with respect to the ball socket 16, and moves with it in 35 relation to the coupling ball. The sealing path 42 bears against a point on the coupling ball in such a way that a surface normal - 12 vector N, starting from the sealing path 42, of the surface of the coupling ball 12 has a directional component NB which is opposed to the lifting off direction A. This ensures that when there is a relative 5 movement of the ball socket 16 in relation to the coupling ball 12 in the lifting off direction A, the sealing effect of the seal 38 is increased since the sealing path 42 is then moved toward the great circle 26, and owing to the increasing diameter of the sealing 10 path 42 the elastic deformation of the sealing lip 40 increases so that the latter presses with increased restoring force against the surface of the coupling ball 12. 15 Figure 2 illustrates a second embodiment of the present invention. Identical components to those in figure 1 are provided with the same reference symbols in figure 2, but increased by the number 100. In order to explain these components, reference is made expressly 20 to their description in relation to figure 1. The embodiment illustrated in figure 2 is explained only insofar as it differs from the embodiment in figure 1. While the circumferential seal 38 in figure 1 is 25 inserted into a continuous annular groove 39, which is also circumferential, in the ball socket 16, in the embodiment in figure 2 a seal 138 is screwed onto the ball socket 116 by screws 150 as fastening means. The seal 138 is fitted here onto the ball socket 116 at the 30 mouth 118 and is screwed to said ball socket 116 by means of a plurality of screws 150. The seal 138 also constitutes a circumferential, continuous ring. The seal 138 comprises a metallic ring 35 as a seal carrier 145 onto which a seal main body 144 with a sealing lip 140 which projects therefrom in the radial direction with respect to the axis R of symmetry is vulcanized. However, the seal body 144 can also be - 13 connected to the seal carrier 145 in some other way, for example by bonding and/or riveting. The seal carrier 145 is surrounded on the outside in the radial direction and centered with respect to the symmetry R 5 by a centering means, here by a circumferential projection 117. While the sealing lip 40 illustrated in figure 1 is ideally in contact with the surface 23 of the coupling 10 ball 12 along a linear sealing path 42, the sealing lip 140 of the seal 138 in figure 2 bears against the spherical surface 123 of the coupling ball 112 along a planar, annular sealing path 142. The sealing path 142 bears, as does the sealing path 42, in an orthogonal 15 plane with respect to the axis R of symmetry of the ball socket 16 and 116, respectively in figures 1 and 2. This plane has, in the case of figure 2, a certain thickness, specifically a thickness which corresponds to the axial extent of the sealing path 142. 20 The seal 138 which is shown in figure 2 can very easily be removed from the ball socket 116 by releasing the screws 150, and can be replaced by a new seal 138. As a result it is possible to release and replace worn or 25 damaged seals with a small number of maneuvers. In the embodiment in figure 1, the seal 38 can be replaced by removing it from the circumferential groove 39 and inserting a new seal 38 into the circumferential 30 groove 39. The embodiments in figures 1 and 2 can also be applied in combination so that a ball-shaped coupling according to the invention comprises at least one seal for 35 sealing the bearing area. It is to be added that the circumferential groove 39 which is shown in figure 1 can, instead of being formed - 14 as an indent, also be formed as a constructed groove by means of the ball socket and a further component which is connected to it. In this context, the groove can be bounded, for example, in two directions by one element 5 - the ball socket or a further component - and can be bounded in a third direction by the respective other element.

Claims

1. A ball-shaped coupling for coupling a towing vehicle to a trailer, which ball-shaped coupling 5 comprises a coupling ball (12; 112) and a ball socket (16; 116) which can be coupled thereto and, in the coupled state, surrounds a section of the coupling ball (12; 112) and bears with an opposed bearing face (22; 112) against a bearing face (24, 124) of the coupling 10 ball (12, 112) so as to form a common bearing area (28, 128), characterized in that a seal (38; 138), which seals off the bearing area (28; 128) from the surroundings, is provided between the coupling ball (12; 112) and the ball socket (16; 116). 15

2. The ball-shaped coupling as claimed in claim 1, characterized in that the seal (38; 138) is a seal (38; 138) which extends along a circular path and is preferably circumferential, and whose bearing location 20 against one of the components of the coupling ball (12; 112) or ball socket (16; 116) is a sealing path (42; 142) which is part annular, preferably annular.

3. The ball-shaped coupling as claimed in claim 2, 25 characterized in that the diameter of the sealing path (42; 142) is smaller than the largest diameter (26) of the coupling ball (12; 112).

4. The ball-shaped coupling as claimed in claim 3, 30 characterized in that in the coupled state, a section (between 42; 142 and 29; 129), which is parallel to the sealing path (42; 142), of the coupling ball (12; 112) is located between the seal (38; 138) and the bearing area (28; 128) and has a larger diameter (26; 126) than 35 the diameter of the sealing path (42; 142).

5. The ball-shaped coupling as claimed in one of the preceding claims, characterized in that the seal (38; - 16 138) is secured to the ball socket (16; 116) and can be moved with it in relation to the coupling ball (12; 112). 5

6. The ball-shaped coupling as claimed in claims 4 and 5, characterized in that the sealing path (42; 142) is defined by the seal (38; 138) bearing against the coupling ball (12; 112), wherein the seal (38; 138) bears against an area of the coupling ball (12; 112) in 10 such a way that at least for a section of the sealing path (42; 142), preferably for the entire sealing path (42; 142), a surface normal vector (N), starting from the sealing path (42; 142), of the coupling ball surface (23; 123) has a component (NB) which is directed 15 in the opposite direction from a respective lifting off direction (A) of the ball socket (16; 116) from the coupling ball (12; 112).

7. The ball-shaped coupling as claimed in one of the 20 preceding claims, including claim 2, characterized in that the seal (38; 138) comprises a sealing lip (40; 140) which in the coupled state can move in the radial direction. 25

8. The ball-shaped coupling as claimed in one of the preceding claims, characterized in that the ball socket (16) comprises an essentially concave, part spherical opposed bearing face (22) and also an insertion section (20a) which is located between the mouth (18) of the 30 ball socket and the opposed bearing face (22), wherein the seal (38) is arranged in the insertion section (20a).

9. The ball-shaped coupling as claimed in claim 8, 35 characterized in that the seal (38) is introduced into a circumferential groove (39) in the insertion section (20a). - 17

10. The ball-shaped coupling as claimed in one of the preceding claims, characterized in that the seal (138) comprises a seal carrier (145) which is separated from the coupling ball (112) and the ball socket (116), 5 wherein the seal carrier (145) is attached with fastening means (150) to one of the components: coupling ball (112) and ball socket (116).

11. The ball-shaped coupling as claimed in claim 10, 10 characterized in that the seal (138) is attached to the mouth (118) of the ball socket (116), preferably attached in a releasable fashion.

12. The ball-shaped coupling as claimed in claim 10 or 15 11, characterized in that the seal carrier (145) is formed from metal, having a seal main body (144) which is connected thereto, preferably by vulcanizing on.

13. The ball-shaped coupling as claimed in one of the 20 preceding claims, characterized in that the opposed bearing face (22; 122) has at least one lubricant pocket (30, 32; 130, 132) in which the surface areas of the bearing face (24; 124) and opposed bearing face (22; 122) are arranged in the coupled state at a radial 25 distance from one another such that lubricant can be stored between these surface areas.

14. The ball-shaped coupling as claimed in one of the preceding claims, characterized in that in the coupled 30 state the opposed bearing face (22; 122) can be supplied with lubricant from the outside through a lubricant line (36; 136).

15. The ball-shaped coupling as claimed in claim 14, 35 characterized in that the lubricant line (36; 136) comprises a lubricating nipple which is provided on the ball socket (16; 116).