Hydraulically damping bearing having ribs and rib interruption regions

Abstract

A hydraulically damped hydro-bushing contained within a cage 20 and an outer sleeve 30, the cage and sleeve being axially interlocked and secured by corresponding circumferential ribs 40 (external rib

Description

The invention relates to a hydraulically damping bearing according to Claim 1. Hydrobushings are known. They comprise a cage which is in most instances embedded in elastomer, and an externally circumferential sleeve which is fastened to the cage and secured in the axial direction. In practice it is known to push a metallic sleeve over the cage and to subsequently calibrate said metallic sleeve. The sleeve is reduced in terms of its diameter during this calibration. As a result, a radial protrusion of the cage forms an axial undercut. Alternatively, a metallic sleeve can externally encompass the cage as a result of a local calibration of the end regions of said metallic sleeve, and in this manner generate an axial undercut. Therefore, the external sleeve is secured in relation to sliding off axially. Generating an axial undercut by means of a forming method requires a plastically deformable material for the external sleeve. It is therefore not possible to use this fixing method for a plastics-material external sleeve. Plastics-material external sleeves which are fixed to a plastics-material cage by means of a welding method, so as to be secured in relation to slipping off axially, are known as an alternative. Such a construction is disclosed in EP 2522878 Bl, for example. However, welding both components first requires a costly investment in a suitable welding apparatus and very meticulous monitoring of the weld quality. It is moreover known in practice to screw a plastics-material external sleeve to a plastics-material cage. The thread forms the axial fixing, but the thread per se does not establish any tightness between the plastics-material external sleeve and the plastics-material cage, so that additional encircling seals are required. However, in order to be able to transmit sufficiently high axial forces, the threads have to be rotated into one another by a plurality of revolutions so as to mutually engage in one another over a certain length. Consequently, the external sleeve has to be rotated / screwed in by a plurality of revolutions relative to the cage. The seal is also highly stressed as a result. Moreover, high torques are required for this threaded connection, which have to be transmitted to the comparatively thin external sleeve . Embodiments of the present invention seek to provide a hydraulically damping bearing which overcomes the aforementioned issues. Primary features of the invention are set forth in the characterizing part of Claim 1. Preferred or alternate embodiments are the subject matter of Claims 2 to 10. Proposed according to an embodiment of the invention is a hydraulically damping bearing which is penetrated by a central longitudinal axis, comprising a cage, an external sleeve and an axial securing means for securing the external sleeve axially on the cage, wherein the axial securing means comprises external circumferential ribs on the cage and internal circumferential ribs on the external sleeve, which extend each in the circumferential direction and can engage in one another, wherein the cage forms on the external circumference at least two external rib interruption regions, and the external sleeve forms at least two internal rib interruption regions, in such a way that, in an axial relative movement between the cage and the external sleeve along the central longitudinal axis, the external circumferential ribs can be moved through the internal rib interruption regions, and the internal circumferential ribs can be moved through the external rib interruption regions. The invention thus seeks to provide regions to push the ribs of the respective other part of cage and axial sleeve axially through these regions along the central longitudinal axis. These interruption regions enable the ribs of the one part to be displaced axially past the ribs of the other part. In this way, the external sleeve can be easily pushed onto the cage during assembling. The interruption regions serve and are designed as axially extending advancing zones. After the axial relative movement between the cage and the external sleeve, these two parts can be rotated relative to one another about the central longitudinal axis. As a result, the internal circumferential ribs and the external circumferential ribs can engage in one another and lie against one another in order to fix the external sleeve axially on the cage. The ribs are disposed on the respective circumferential face of the cage and the external sleeve, and protrude therefrom in the radial direction. A trough, which follows the ribs in the circumferential direction, is formed between axially adjacent ribs. A rib of the other part of cage and external sleeve can engage in the trough. The interruption regions can be free of ribs and / or be formed by a respective cylindrical circumferential face of the cage and external sleeve, and / or be delimited in the circumferential direction by the ends of the ribs. The troughs can open out towards the corresponding interruption region. It is conceivable that the circumferential length of all ribs between interruption regions that are adjacent in the circumferential direction is identical. It is conceivable that axially adjacent ribs are co-aligned in the axial direction at one end, preferably both ends. This can result in axially extending advancing zones. The bearing moreover comprises an elastomer member and chambers which are filled, or able to be filled, with a fluid and are able to be delimited by soft inflatable elastomer membranes. The cage is embedded in the elastomer member in order to reinforce the soft inflatable elastomer membranes. In order to prevent any leakage of the fluid-filled chambers, the latter are sealed in relation to the environment. For this purpose, the elastomer membranes can be provided with sealing means which sit on the cage. Embodiments of the invention therefore seek to enable axial fixing of the external sleeve in a surprisingly simple manner, without the latter having to be formed and without any rotational movement covering a plurality of full revolutions. According to a conceivable refinement of the hydraulically damping bearing, at least one sealing means can be disposed between the cage and the external sleeve. The axial relative movement between the cage and the external sleeve, and / or the circumferential relative movement between the cage and the external sleeve, can take place counter to the force of the sealing means and shear and / or compress the latter. The circumferential position of the cage and of the external sleeve relative to one another can be secured by the compressed and / or sheared sealing means. Each ring of the cage can support a sealing means, preferably a sealing ring. According to a conceivable refinement of the hydraulically damping bearing, ribs which are axially spaced apart (e.g. external circumferential ribs and / or internal circumferential ribs) and disposed in the circumferential direction between two adjacent interruption regions can define a rib block. According to a refinement of the hydraulically damping bearing, the external rib interruption regions and internal rib interruption regions can each be delimited in the circumferential direction by the respective ribs, and / or extend each so as to be parallel to the central longitudinal axis. As a result, the ribs, while being in the interruption region of the respective other part of cage and external sleeve, can easily engage out of the axial movement by way of a rotating movement between the ribs of the respective other part of cage and external sleeve. A simple transition is achieved as a result. The advantage of axially extending interruption regions lies in that an axial relative movement between the cage and the external sleeve can be free of any movement in the circumferential direction. Pre-assembling is significantly simplified as a result, and the sealing means are subjected to little tribological stress and only to minor shear forces due to tilting during the axial relative movement. According to a refinement of the hydraulically damping bearing, the cage can form two, three or four external rib interruption regions, and the external sleeve can correspondingly form two, three or four internal rib interruption regions. The number of interruption regions can be a function of the diameter of the cage, or of the external sleeve, respectively. An increase in the diameter while at the same time maintaining the number of interruption regions leads to a longer movement range having to be travelled in a relative rotating movement between the cage and the external sleeve. Therefore, the external diameter of the cage in the region of the external circumferential ribs can advantageously be linked to the number of external rib interruption regions, this applying in an analogous manner to the external sleeve. According to a conceivable refinement of the hydraulically damping bearing, the external rib interruption regions can be mutually disposed, and the internal rib interruption regions can be mutually disposed, so as to be each equidistant in the circumferential direction. As a result, the cage and the external sleeve can be pre-assembled at different mutual alignments because a plurality of orientations are possible. This simplifies the assembly process. According to a refinement of the hydraulically damping bearing, at least two, preferably three, furthermore preferably four, external circumferential ribs can in each case be disposed between adjacent external rib interruption regions, and / or at least two, preferably three, furthermore preferably four, internal circumferential ribs can each be disposed between adjacent internal rib interruption regions. The numbers stated can indicate the exact quantity so that not fewer and not more are present. As the number of ribs increases, so does the axial force that can be transmitted between the external sleeve and the receptacle boss by means of a press-fit before the yield point of the ribs is reached. According to a refinement of the hydraulically damping bearing, the external circumferential ribs and internal circumferential ribs can run each in the circumferential direction at a zero pitch, or form each a thread. The ribs running in the circumferential direction without a pitch (zero pitch) do not have any thread pitch. In the absence of such a pitch, they implement a very high degree of self-locking in relation to being released, but twisting of the cage and the external sleeve is impeded. In contrast, the ribs in the design embodiment as thread have a pitch which has the characteristics of a thread. In this case, the self-locking action is indeed lower, but the twisting of the cage and the external sleeve is facilitated. According to a conceivable refinement of the hydraulically damping bearing, the number of turns of the thread can each be one, or correspond to the number of external rib interruption regions or internal rib interruption regions. In the first embodiment, the threads are each single-start threads. As a result, the threads can have each a small pitch. This case is particularly suitable for achieving both easy twisting of the cage and the external sleeve as well as a very high degree of self-locking action of the threads. Moreover, there is a negligibly small tolerance-related correlation between the axial and the rotational position of the cage and the external sleeve in the case of singlestart threads. Threads with multiple starts can simplify assembling because, due to the fact that a multiple-start thread can have a plurality of entrances, the cage and the external sleeve can be pre-assembled at different mutual alignments because a plurality of orientations are possible. The number of entrances can correspond to the number of external rib interruption regions or internal rib interruption regions. According to a conceivable refinement of the hydraulically damping bearing, the external rib interruption regions and / or internal rib interruption regions can be milled regions. Regions of this type may be identified by surface features that are typical of milling. Firstly, the forming of ribs or threads that are completely closed in the circumferential direction is specifically conceivable, defined regions of the ribs or threads then being removed by milling in order to form the interruption regions. As a result, cost-intensive production tools of complex design, such as injectionmoulding tools with complex gates, can be avoided, and / or gates required for moulding other regions do not have to be additionally adapted with gates for the ribs in order to avoid geometric conflicts. According to a refinement of the hydraulically damping bearing, at least one of the external circumferential ribs, preferably only a single one of the external circumferential ribs, can be designed as a poka-yoke external rib which projects in the circumferential direction beyond the axially adjacent external circumferential rib, and at least one of the internal circumferential ribs, preferably only a single one of the internal circumferential ribs, can be designed as a poka-yoke internal rib which is set back in the circumferential direction in relation to the axially adjacent internal circumferential rib. Additionally or alternatively, it is conversely conceivable that at least one of the external circumferential ribs, preferably only a single one of the external circumferential ribs, can be designed as a poka-yoke external rib which is set back in the circumferential direction in relation to the axially adjacent external circumferential rib, and that at least one of the internal circumferential ribs, preferably only a single one of the internal circumferential ribs, can be designed as a poka-yoke internal rib which projects in the circumferential direction beyond the axially adjacent internal circumferential rib. The two poka-yoke ribs conjointly form an axial device for preventing assembling errors. In this instance, the cage and the external sleeve are axially movable relative to one another in only one single orientation. The projecting, or longer, rib specifically prevents that ribs other than the set back, or shorter, rib can be pushed past in the axial direction, or at least be pushed so as to be level. It is possible that all rib blocks, with the exception of those rib blocks that have a poka-yoke rib, comprise identical ribs. This can apply in particular to their circumferential length, entry ramps and axial coalignment . According to a conceivable refinement of the hydraulically damping bearing, the circumferential length of all ribs between interruption regions adjacent in the circumferential direction can be identical, with the exception of the poka-yoke rib. It is conceivable that axially adjacent ribs are mutually co-aligned at one end, preferably at both ends, in the axial direction, but with the exception of the poka-yoke rib. According to a refinement of the hydraulically damping bearing, the cage or the external sleeve can have a poka-yoke rotation direction stop on which a rib of the respective other one of cage and external sleeve can abut in the circumferential direction. Twisting of the cage and the external sleeve in the wrong circumferential direction is avoided as a result. The poka-yoke rotation direction stop forms a circumferential device for preventing assembly errors. The poka-yoke rotation direction stop can be a wall. Therefore, when interacting with the poka-yoke ribs, a multi-stage assembly error device is enabled, because the poka-yoke ribs first serve for the correct axial orientation in an axial relative movement between the cage and the external sleeve, and subsequently the poka-yoke rotation direction stop serves for the correct rotation direction in a circumferential relative movement between the cage and the external sleeve . According to a conceivable refinement of the hydraulically damping bearing, the cage or the external sleeve can have an overtwisting prevention means on which a rib of the respective other one of cage and external sleeve can come to bear in the circumferential direction. Any overtwisting of the cage and the external sleeve in the correct circumferential direction is avoided as a result. The overtwisting prevention means can be a ramp structure which extends in the radial direction. The overtwisting prevention means forms a circumferential device for preventing assembly errors. Therefore, when interacting with the poka-yoke ribs and / or the poka-yoke rotation direction stop, this enables a multi-stage assembly error device. According to a conceivable refinement of the hydraulically damping bearing, the cage or the external sleeve can have an axial web which can form the poka-yoke rotation direction stop on one of its circumferential sides and / or the overtwisting prevention means on its opposite circumferential side. As a result, the axial web can be multifunctional. According to a refinement of the hydraulically damping bearing, one of cage and external sleeve can have at least one latching recess, and the respective other one of cage and external sleeve can have at least one corresponding latching protrusion. The latching recess and the latching protrusion can correspond to one another. The latching recess and the latching protrusion conjointly can form an anti-rotation protection. For this purpose, the latching protrusion can engage in the latching recess so as to avoid any undesirable circumferential release of the cage and the external sleeve during the intended operation of the bearing. It is conceivable that the latching protrusion already latches into the latching recess as a result of the rotating movement during the pre-assembly or assembly of the external sleeve and the cage. It is furthermore conceivable that the protrusion only engages due to the calibration of the bearing during press-fitting of the bearing, for example in a receptacle boss, and an engagement already formed prior to press-fitting, preferably a slight engagement, is reinforced by the press-fitting and / or is furthermore secured in relation to sliding out. The at least one latching recess is advantageously disposed on a circumferential rib flank of an internal circumferential rib, or external circumferential rib, respectively. According to a refinement of the hydraulically damping bearing, the external circumferential ribs and / or internal circumferential ribs can form each an entry ramp (only) on one end, or both ends. The entry ramps serve to introduce the ribs of the one part of cage and external sleeve into the troughs between the ribs of the other one of cage and external sleeve. In a circumferential relative movement between the cage and the external sleeve, the entry ramps slide on one another. As a result, an axial relative movement between the cage and the external sleeve also take place. The latter at least to a minor degree. As a result of the circumferential relative movement interacting with the entry ramps, a very high retaining force can be introduced. This applies in particular to ribs without a thread pitch. The entry ramps can have a gradient in relation to the central longitudinal axis. In the case of entry ramps being provided only on one end, it is conceivable that those sides of the respective ribs lying opposite in the circumferential direction form each one rib stop. Any twisting of the cage and the external sleeve in the wrong circumferential direction can also be avoided as a result. Specifically, the rib stops of the external circumferential ribs can lie against the rib stops of the internal circumferential ribs in order to prevent twisting. In the case of entry ramps being provided only on one end, the respective entry ramps can be located in such a manner that the entry ramps of the ribs of the one part of cage and external sleeve can slide off the entry ramps of the ribs of the other part of cage and external sleeve. When viewed in the longitudinal section, the entry ramps can extend obliquely in relation to the central longitudinal axis. It is conceivable that the poka-yoke internal rib and / or the poka-yoke external rib have / has an entry ramp only on one end. According to a conceivable refinement of the hydraulically damping bearing, the cage can be a casting, for example a plastic injection-moulded casting or an aluminium die-casting. The cage can be made of a plastics material, preferably of a thermoplastic material, and / or the external sleeve can be made of a plastics material, preferably of a thermoplastic material. The invention makes it possible that the external sleeve can be axially secured without being deformed. It is therefore now possible to use a plastics material also tor the external sleeve . According to a refinement of the hydraulically damping bearing, the length of the external rib interruption regions in the circumferential direction can be at least 1 mm, preferably at least 2 mm, longer than the length of the internal circumferential ribs between adjacent internal rib interruption regions in the circumferential direction. Additionally, the length of the internal rib interruption regions in the circumferential direction can be at least 1 mm, preferably at least 2 mm, longer than the length of the external circumferential ribs in the circumferential direction (U) . It is conceivable that the interruption regions in the circumferential direction are at most 5 mm longer than the corresponding ribs. It is conceivable that the internal circumferential ribs and external circumferential ribs are designed in such a manner that they, when positioned in the corresponding interruption region of the other part of cage and external sleeve, can form a radial play of at least 1 mm, preferably at least 2 mm. It is conceivable that the radial play is at most 5 mm. As a result of this play, the cage and the external sleeve can be pushed axially into one another by way of a reliable process. A smaller play may require an excessive positioning precision during pre-assembly, while an excessive play may however reduce the face of the ribs that performs axial securing, this potentially reducing a maximum achievable axial force . According to a conceivable refinement of the hydraulically damping bearing, the cage can have two rings which are connected to one another by at least one web, wherein the external circumferential ribs and external rib interruption regions are formed only on one of the rings, preferably so as to be in one piece with the ring, thus formed by the ring. If both rings were to be provided with external circumferential ribs and external rib interruption regions, a corresponding pair of internal ribs on the internal circumferential face of the external sleeve would have to pass through a large part of the core during the pre-assembly or assembly of the external sleeve. For this purpose, it would be necessary to provide matching clearances also in the region between the rings, for example. In such a case, it would then not be possible, or possible only with additional complexity, to place ring support elements such as duct half-shells or other inserts, axially between the rings in such a manner that they, conjointly with the external sleeve, form a fluid duct for the hydraulic function of the hydraulically damping bearing. Alternatively, the internal face of the external sleeve would have to be embodied with steps, i.e. the rings which are provided with the ribs would have to have a different diameter so that the ribs placed on the internal side of the external sleeve do not collide with the region between the ribs when the external sleeve is being pushed on. In such a case, however, the bearing would have to make available in its installation space the larger diameter at least in the region of the ring having the latter, potentially leading to an overall larger bearing. According to a conceivable refinement of the hydraulically damping bearing, a rib block of external circumferential ribs and / or internal circumferential ribs, preferably each rib block of external circumferential ribs and / or internal circumferential ribs, can extend in the circumferential direction over at most M of the circumference of the bearing. This reduces shear stress and tribological abrasion on the sealing means during twisting of the cage and the external sleeve. According to a conceivable refinement of the hydraulically damping bearing, a rib block of external circumferential ribs and / or internal circumferential ribs, preferably each rib block of external circumferential ribs and / or internal circumferential ribs, can have a developed length of at most 50 mm, preferably of at most 30 mm. This reduces shear stress and tribological abrasion on the sealing means during twisting of the cage and the external sleeve. According to a conceivable refinement of the hydraulically damping bearing, the cage can support elastomer axial stops. The axial stops can extend in the axial direction and / or act in the axial direction. The axial stops can be interrupted in the circumferential direction, at least on an axial end side of the cage. The axial stops serve as buffers when abutting on, or being abutted by, a component which is separate from the bearing. The axial stops can be formed axially on one end, or axially on both ends, on the cage. It is conceivable that the elastomer member forms the axial stops . According to a conceivable refinement of the hydraulically damping bearing, the rib blocks of external circumferential ribs, preferably all rib blocks of external circumferential ribs, can each be co-aligned axially with an elastomer axial stop, preferably be disposed so as to be centred in the axial direction in relation to said elastomer axial stop. This serves to improve the force flux in the cage during buffering, and prevents a deflected force flux which could lead to damage to the cage. Further features, details and advantages of the invention are derived from the wording of the claims and from the description hereunder of exemplary embodiments by means of the drawings, in which: Fig. 1 shows a longitudinal section view through a bearing according to an embodiment of the invention; Fig. 2 shows a cage of the bearing in a standalone illustration; and Fig. 3 shows an external sleeve of the bearing in a standalone illustration. Identical or mutually equivalent elements are each denoted by the same reference signs in the figures, and are therefore not described once again unless this is expedient. Features which have already been described are not described once again in order to avoid repetitions, and are applicable to all elements with identical or mutually equivalent reference signs, unless explicitly excluded. The disclosures contained in the entire description can be applied in an analogous manner to identical parts with the same reference signs, or component designations, respectively. The positional specifications chosen in the description such as, tor example, above, below, laterally, etc., are also made with reference to the directly described and illustrated figure and, in the case of a change in position, are to be transferred analogously to the new position. Furthermore, individual features or combinations of features of the different exemplary embodiments shown and described may represent independent inventive solutions, or independent solutions according to the invention. Figure 1 shows a hydraulically damping bearing 10 in longitudinal section. The bearing 10 is penetrated in the axial direction by a central longitudinal axis Z. The radial direction R and the circumferential direction U extend in relation to the central longitudinal axis Z. The bearing 10 comprises a cage 20 which is shown in detail in Figure 2. The cage 20 has two rings 20a, 20b which are axially spaced apart and are connected to one another by two webs 20c, 20d. Shell-shaped ring support elements 14, which can also contain a portion of a duct, are placed on both sides between the rings 20a, 20b. The bearing 10 also comprises an external sleeve 30 which is shown in detail in Figure 3. The external sleeve 30 surrounds the cage 20 on the external circumference. The bearing 10 furthermore comprises an axial securing means 40 which acts between the cage 20 and the external sleeve 30. The bearing 10 moreover comprises an elastomer member 50 which delimits chambers 12 that are filled, or able to be filled, with fluid. The cage 20 is embedded in the elastomer member 50. Two sealing means 52, presently in the form of sealing rings which are formed by the elastomer member 50, are disposed between the cage 20 and the external sleeve 30. Furthermore, the elastomer member 50 forms on one end axial stops 54 which are disposed on the end side on the cage 20 and are interrupted in the circumferential direction U. Moreover, the elastomer member 50 forms on the other end an axial stop 56 which is disposed on the end side on the cage 20 and is continuous in the circumferential direction U. In the embodiment shown, the axial securing means 40 comprises on the cage external circumferential ribs 21 which are formed so as to be mutually spaced apart axially and radially on the ring 20a. The external circumferential ribs 21 are provided on the external circumference of the cage 20, protrude therefrom in the radial direction R, and extend at a zero pitch in the circumferential direction U. A trough 21a, which follows the external circumferential ribs 21 in the circumferential direction U, is formed between axially adjacent external circumferential ribs 21. Moreover, the axial securing means 40 comprises on the cage regions in which these external circumferential ribs 21 are interrupted in the circumferential direction U, i.e. so-called external rib interruption regions 22 which extend parallel to the central longitudinal axis Z. This results in axially extending advancing zones. The external rib interruption regions 22 here are free of external circumferential ribs 21 and are formed by the cylindrical external circumferential face of the ring 20a. Moreover, the external rib interruption regions 22 are delimited in the circumferential direction U by the ends of the external circumferential ribs 21. The troughs 21a are open towards the corresponding external rib interruption region 22. The external circumferential ribs 21 which are axially adjacent and disposed in the circumferential direction U between two adjacent external rib interruption regions 22 define each one rib block 21b, 21c. Each rib block 21b, 21c extends in the circumferential direction U over at most M of the circumference of the bearing 10, and has a developed length of at most 50 mm. Each rib block 21b, 21c is coaligned in the axial direction, or along the central longitudinal axis Z, with an axial stop 54 which is interrupted in the circumferential direction U. The axial securing means 40 comprises on the external sleeve internal circumferential ribs 31 which are formed so as to be axially and radially spaced apart from one another on the external sleeve 30. The internal circumferential ribs 31 are provided on the internal circumference of the external sleeve 30, protrude therefrom in the radial direction R, and extend at a zero pitch in the circumferential direction U. A trough 31a, which follows the internal circumferential ribs 31 in the circumferential direction U, is formed between axially adjacent internal circumferential ribs 31. Furthermore, the axial securing means 40 comprises on the external sleeve regions in which these internal circumferential ribs 31 are interrupted in the circumferential direction U, i.e. so-called internal rib interruption regions 32 which extend parallel to the central longitudinal axis Z. This results in axially extending advancing zones. The internal rib interruption regions 32 here are free of internal circumferential ribs 31 and are formed by the cylindrical internal circumferential face of the external sleeve 30. Moreover, the internal rib interruption regions 32 are delimited in the circumferential direction U by the ends of the internal circumferential ribs 31. The troughs 31a are open towards the corresponding internal rib interruption region 32. The internal circumferential ribs 31 which are axially adjacent and are disposed in the circumferential direction U between two adjacent internal rib interruption regions 32 define each one rib block 31b, 31c. Each rib block 31b, 31c extends in the circumferential direction U over at most M of the circumference of the bearing 10, and has a developed length of at most 50 mm. Provided in the embodiment shown are each four interruption regions 22, 32, and thus also four rib blocks 21b, 21c, 31b, 31c with ribs 21, 31. The external rib interruption regions 22 can be disposed so as to be mutually equidistant, whereby the same can also apply in an analogous manner to the internal rib interruption regions 32. The external rib interruption regions 22 and the internal rib interruption regions 32 can be milled regions, or be produced directly during casting, for example by means of injection-moulding. Three internal circumferential ribs 21, or external circumferential ribs 31, respectively, are each disposed between adjacent interruption regions 22, 32 in the respective rib block 21b, 21c, 31b, 31c. A single one of the external circumferential ribs 21 is designed as poka-yoke external rib 25. The latter protrudes in the circumferential direction U beyond the axially adjacent external circumferential rib 21. A single one of the internal circumferential ribs 31 is designed as a poka-yoke internal rib 35, wherein the latter is set back in the circumferential direction U in relation to the axially adjacent internal circumferential rib 31. The two poka-yoke ribs 25, 35 correspond to one another and form an axial device for preventing assembly errors . It can be seen that the circumferential length of all external circumferential ribs 21 and internal circumferential ribs 31 with the exception of the poka-yoke external rib 25, or poka-yoke internal rib 35, respectively, within the respective rib block 21b, 21c, 31b, 31c is identical. It can moreover be seen that all external circumferential ribs 21 and internal circumferential ribs 31, with the exception of the poka-yoke external rib 25, or poka-yoke internal rib 35, respectively, within the respective rib block 21b, 21c, 31b, 31c, are at both ends mutually co-aligned in the axial direction. The cage 20 forms on its external circumferential side an axial web 23. The axial web 23 protrudes therefrom in the radial direction R, and extends in the axial direction. At one end, the axial web 23 can transition into the poka-yoke external rib 25. The axial web 23 forms on one of its circumferential sides an overtwisting prevention means 24, and forms on its opposite circumferential side a poka-yoke rotation direction stop 26. The overtwisting prevention means 24 is shown as a ramp structure which extends in the radial direction R. An internal circumferential rib 31 can abut or run against the overtwisting prevention means 24; any overtwisting of the cage 20 and the external sleeve 30 in the circumferential direction U is avoided. The poka-yoke rotation direction stop 26 is shown as a wall. An internal circumferential rib 31 can abut the poka-yoke rotation direction stop 26; a rotation of the cage 20 and the external sleeve 30 in the wrong circumferential direction U is avoided. The cage 20 has on its external circumferential face a plurality of latching protrusions 27, whereby each of the rib blocks 21b, 21c is assigned one latching protrusion 27. The external sleeve has on its internal circumferential face, on internal circumferential rib flanks of internal circumferential ribs 31, a plurality of latching recesses 37 which correspond to the latching protrusions 27, whereby each of the rib blocks 31b, 31c is assigned one latching recess 37. Each latching protrusion 27 can engage in one latching recess 37. The external circumferential ribs 21 have each on one end an entry ramp 28, and on the opposite end a rib stop 29. The internal circumferential ribs 31 likewise have each on a corresponding end an entry ramp 38, and on the opposite end a rib stop 39. The entry ramps 28, 38 guide the respective rib 21, 31 out of the interruption region 22, 32 into the respective trough 21a, 31a. Therefore, the entry ramps 28, 38 are located in such a manner that the entry ramps 28 of the external circumferential ribs 21 can slide off the entry ramps 38 of the internal circumferential ribs 31. The external circumferential ribs 21 and the internal circumferential ribs 31 are designed in such a manner that they, when positioned in the corresponding interruption region 22, 32 of the other part of cage 20 and external sleeve 30, form a radial play of at least 1 mm. Pre-assembling is to be described hereunder, whereby preassembling is understood to mean a procedure by way of which the bearing per se is completely produced. The bearing per se is to be complete upon pre-assembly. Assembling is understood to be a procedure by way of which the bearing is fixedly established at or in its intended operational destination. The cage 20 and the external sleeve 30 are mutually positioned in such a manner, and then moved relative to one another and axially converged in such a manner, that the external circumferential ribs 21 of the cage 20 can be advanced axially through the internal rib interruption regions 32 of the external sleeve 30, and the internal circumferential ribs 31 of the external sleeve 30 can be advanced axially through the external rib interruption regions 22 of the cage 20. Thereafter, the cage 20 and the external sleeve 30 are twisted relative to one another in the circumferential direction U, whereby the entry ramps 28, 38 slide on one another and introduce the respective rib 21, 31 into the respective trough 21a, 31a. Thereafter, the rib blocks 21b, 21c of the cage 20 engage in the rib blocks 31b, 31c of the external sleeve 30. The poka-yoke rotation direction stop 26 prevents any twisting in the wrong direction. The overtwisting prevention means 24 prevents overtwisting in the correct direction. The sealing means 52 is pre-loaded as a result of the pre-assembly or assembly of the cage 20 and the external sleeve 30, so that said sealing means 52 can fulfil its sealing function. The invention is not restricted to any one of the abovedescribed embodiments, but may be modified in a variety of ways. All of the features and advantages that emerge from the claims, from the description and from the drawing, including structural details, spatial arrangements and method steps, may be essential to the invention both individually and in a wide variety of combinations . The invention encompasses all combinations of at least two of the features disclosed in the description, the claims and / or the figures. To avoid repetitions, it is the intention that features disclosed in device terms are also disclosed, and capable of being claimed, in method terms. It is likewise the intention that features disclosed in method terms are disclosed, and capable of being claimed, in device terms. The content of priority application DE10204101793.7 and the abstract accompanying this application are incorporated by reference herein. List of reference signs Bearing Chamber Ring support element Cage Ring Ring Web Web External circumferential rib Trough Rib block Rib block External rib interruption region Axial web Overtwisting prevention means Poka-yoke external rib Poka-yoke rotation direction stop Latching protrusion Entry ramp Rib stop External sleeve Internal circumferential rib Trough Rib block Rib block Internal rib interruption region Poka-yoke internal rib Latching recess Entry ramp Rib stop 40 Axial securing means 50 Elastomer member 52 Sealing means 54 Axial stop 56 Axial stop R Radial direction U Circumferential direction Z Central longitudinal axis

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