Abstract:
An elastic joint body for the articulated connection of two shaft sections includes a plurality of bushings arranged in the circumferential direction in predetermined angular intervals with respect to a center axis of the joint body, a plurality of loop packets wrapping around two adjacent bushings each, and a rubber-elastic casing at least partially embedding the loop packets and the bushings. In order to prolong the service life of such a joint body and to avoid undesired frictional effects between adjacent loop packets, one support arrangement is at least partially embedded in the rubber-elastic casing, with the support arrangement supporting at least part of a loop packet between adjacent bushings.

Description:
This application claims priority to PCT Application No. PCT/EP2009/003270, filed on May 7, 2009, under Section 371 and/or as a continuation under Section 120, which claims priority to German Application No. 102008022475.8, filed on May 7, 2008. 
     TECHNICAL FIELD 
     The present invention relates to an elastic joint body for a shaft arrangement for the articulated connection of two shaft sections, comprising a plurality of bushings which are arranged in the circumferential direction in predetermined angular intervals with respect to a centre axis of the joint body, a plurality of loop packets, wherein each loop packet wraps around two adjacent bushings, and a rubber-elastic casing into which the loop packets and the bushings are at least partially embedded. 
     BACKGROUND 
     Such joint bodies are known from the prior art and are disclosed e. g. in the unexamined German application DE 27 05 598 A1. This document describes an elastic joint disk, wherein textile loop packets each surround two adjacent bushings, and this arrangement is embedded in a rubber mass. Although such joint disks enjoy a wide-range acceptance and exhibit high reliability with an already long service life, recent efforts are directed to design joint disks in view of the increasing loads due to continuously increasing motor outputs and to prolong the service lives even further. 
     From the state of the art, further solutions are known for elastic joint bodies for the connection of two shaft sections. 
     Document DE 42 04 973 A1, for example, indicates a joint disk with a basic skeleton made of synthetic material. The basic skeleton consists of six plastic segments which are integrally injection-moulded together with an outer sleeve. The outer sleeve comprises an inner sleeve which is in connection with the outer sleeve and the plastic segments via rubber buffers. The movability of the inner sleeve is ensured by slots between the rubber buffers. The basic skeleton with the plastic segments and the sleeves accommodated therein is embedded in caoutchouc by injection moulding for manufacturing the joint disk and subsequently vulcanised. 
     Further, DE 42 43 447 A1discloses a coupling element for torque transmission with six areas made from elastic material, which are alternately provided with three reinforcing inserts and are arranged in a basic body of the coupling element. The basic body is provided with three triangular recesses, each of which is capable of accommodating a metallic triangular body with a hole and, together with the basic body, forming the coupling element. With holes provided on the triangular bodies, the coupling element may be mutually screw-connected with flanges of shaft sections. 
     Document DE 10 2006 001 200 A1 discloses a flexible drive train coupling with an insert which comprises a first and a second insert element. Each of the two insert elements comprises a mounting portion to be attached at shaft sections and both are arranged at a central hub section. A second material is poured over the insert elements, which spreads within the spaces between the two insert elements and forms a sheath for the insert elements. 
     In the above described state of the art, various constructive design possibilities for a joint body for the transmission of torques between the shaft sections are described, each of which being reinforced by inserts or insert elements from a material other than that which is used for the rubber-elastic casing. 
     In contrast, it is the object of the present invention to provide an elastic joint body of the initially mentioned kind, which meets the increased requirements of the torque transmission and which simultaneously enables a prolonging of the service life. 
     SUMMARY OF THE INVENTION 
     This object is solved by an elastic joint body of the initially mentioned kind, in which a support arrangement is embedded at least partially in the rubber-elastic casing, and in which the support arrangement supports at least part of a loop packet between adjoining bushings. 
     By using a support arrangement with the inventive elastic joint body, the proportion of the force absorption or the load-carrying proportion, respectively, of the loop packets is increased. Moreover, the loop packets are prevented from coming into frictional engagement, which would negatively affect the life of the joint body. The support arrangement prevents such friction effects to a large extent. In addition, the elastic joint body is reinforced by the support arrangement, which enables higher torque absorption. The support arrangement in general provides for an improved guide of the thread packets in the joint body. This arrangement increases the load- carrying proportion of each thread packet so that the joint body in its entirety is able to withstand higher loads over a longer operating period. 
     In an advancement of the invention, it is provided that pairs of adjacent bushings are surrounded by at least one of the loop packets. The support arrangement forms a guide for the loop packets 
     Furthermore, it is provided in an advancement of the invention that the at least one support arrangement comprises an insert body which is arranged in a spaced relationship between two adjacent bushings as stress relief and support of the parallel strands of the loop packets. By providing an insert body in the inventive joint body, higher torques may be transmitted, with the outer dimensions remaining constant. The insert bodies may be constructively designed in such a manner that they permit a more advantageous surface pressure between the individual components of the support arrangement. Thereby, stress peaks in the joint body may be avoided and the mechanical loads which occur during operation may be distributed more evenly in the joint body. 
     In order to be able to accommodate and guide the loop packets, a preferred embodiment provides for reception areas in the insert body for parallel strands of at least one loop packet. Due to the joint bodies which are arranged between two adjacent bushings, the loop packets, especially at the outer circumference of the elastic joint body, may be better supported compared to conventional joint bodies, thereby increasing the load-carrying proportion. 
     Because the loop packets of the elastic joint body which wrap around adjoining bushings are alternately subjected to a tensile or compressive stress because they are alternately located in a tensile section subject to tensile forces and a compression section subject to compression forces for installation reasons, usually two loop packets are arranged at a portion of the elastic joint body which is subjected to a compressive force, while only one loop packet is provided in a tensile section. For this reason, an advancement of the invention provides for such a construction of the joint body that in the joint body successive bushing pairs in the circumferential direction are alternately surrounded by a loop packet pair or a single loop packet, with at least one insert body being provided between two adjoining bushings which are surrounded by a loop packet pair. The insert body comprises reception areas for parallel strands of the loop packet pair. Between two bushings which are surrounded by a single loop packet, at least one insert body is provided which comprises reception areas for parallel strands of the single loop packet. 
     Because the bushings are arranged in the circumferential direction in predetermined angular intervals with respect to a centre axis of the joint body, an advancement of the invention provides for a plurality of insert bodies to be also arranged in regular angular intervals. 
     By the alternate arrangement of a loop packet pair and a single loop packet depending on the portions of the elastic joint body which are subject to a compressive force or a tensile force, a further embodiment of the invention provides for the accommodation and support of the loop packets, wherein the at least one insert body comprises reception areas between the bushings for the loop packet pair at corner areas of the insert body. In this context, it should be mentioned with respect to the accommodation of a loop packet which is subject to a tensile force that the insert body comprises reception areas for a single loop packet in a centre portion of the insert body. 
     In order to achieve a support of the loop packets as stably as possible also in the area of the bushings, another embodiment of the invention provides that the support arrangement comprises at least one support body which is allocated to a single bushing. In this context, the invention may provide that the at least one support body which is allocated to a bushing comprises at least one guideway for at least one loop packet. 
     As already mentioned above, one bushing is wrapped or surrounded by several, in particular three, loop packets. For separating the individual loop packets from each other in the area of the bushing and for preventing service life-reducing friction effects during operation of the inventive joint body between the loop packets made from the same material, it may be provided according to another embodiment of the invention that the at least one support body which is allocated to one bushing comprises an upper and a lower guideway for a loop packet pair, as well as a centre guideway between the upper and lower guideways that may receive one loop packet surrounded one bushing pair. Preferably, the loop packet which is subjected to a tensile force is accommodated in the centre guideway, while the two loop packets of a loop packet pair in the upper and lower guideways are subjected to a compressive force. Thus, the support bodies with the guideways separate the loop packets which are subjected to different forces from each other. 
     With respect to the support and to the prevention of friction between adjoining loop packets of the same material, it may be provided according to the invention that the at least one support body at least partially surrounds a plurality of guideways. 
     According to an embodiment of the invention, the insert body and the support body are preferably made from metal, aluminium, non-ferrous alloys, filled or non-filled synthetics or a thermoplastic elastomer. In one particular embodiment of the invention, it may further be provided that the insert body and the support body are preferably reinforced by embedded carbon, glass and/or metal fibres. The insert bodies and the support bodies may, however, also be made from a metal fabric or from formations which resemble compressed metal wool, i. e. from compressed metal fibres. Apart from the above mentioned advantages, such insert parts offer the additional benefit that they are less rigid and can therefore be deformed more easily. In other words, these insert parts made from metal fabric are flexible upon bending of the inventive elastic joint body. 
     For the axial support of the loop packets or the support bodies, respectively, and for holding them in their predetermined position on a bushing, another embodiment of the invention provides for a collar which is attached at each end of a bushing, which axially supports the loop packet on the respective bushing. 
     The invention also relates to a shaft arrangement with an inventive joint body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following, the invention will be explained by way of example with reference to the accompanying figures; in which: 
         FIG. 1   a  is a perspective view of a first embodiment of the invention; 
         FIG. 1   b  is a plan view of the first embodiment of the invention; 
         FIGS. 1   c  and  1   d  are sectional views of the first embodiment of the invention; 
         FIG. 2   a  is a perspective view of a second embodiment of the invention; 
         FIG. 2   b  is a front view of the second embodiment of the invention; 
         FIGS. 2   c  and  2   d  are sectional views of the second embodiment of the invention; 
         FIG. 3   a  is a perspective view of a third embodiment of the invention; 
         FIG. 3   b  is a plan view of the third embodiment of the invention; 
         FIGS. 3   c  and  3   d  are sectional views of the third embodiment of the invention; 
         FIG. 4   a  is a perspective view of a fourth embodiment of the invention; 
         FIGS. 4   b  and  4   c  show a front view and a sectional view of the fourth embodiment of the invention; 
         FIG. 5   a  is a perspective view of a fifth embodiment of the invention; 
         FIGS. 5   b  and  5   c  show a front view and a sectional view of the fifth embodiment of the invention; 
         FIG. 6   a  is a perspective view of a sixth embodiment of the invention; 
         FIGS. 6   b  and  6   c  show a front view and a sectional view of the sixth embodiment of the invention; 
         FIG. 7   a  is a perspective view of a seventh embodiment of the invention; 
         FIGS. 7   b  and  7   c  show a front view and a sectional view of the seventh embodiment of the invention; 
         FIGS. 8   a  and  8   b  show views of a support body allocated to a bushing; 
         FIGS. 9   a  and  9   b  show views of a support body allocated to a bushing; and 
         FIGS. 10   a  and  10   b  show views of a support body allocated to a bushing. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1   a shows a perspective view of a first embodiment of the inventive elastic joint body  10  with six bushings  14  which are surrounded by a rubber-elastic casing  12 . 
     The bushings  14  are arranged in predetermined angular intervals in the circumferential direction with respect to a centre axis M of the joint body  10 . In the cut-away area of the joint body, which is shown in the foreground of the drawing according to  FIG. 1   a , a support arrangement  16  with an insert body  18  and support bodies  20  and  22  which are allocated to each of the bushings  14  can be seen. Further, collars  24  can be seen in  FIG. 1   a , which are arranged at the bushings  14  for the axial support of loop packets  26 ,  28  and  30 . 
     The loop packets  26 ,  28  and  30  are guided or accommodated, respectively, in guideways which are formed at the support bodies  20 ,  22  and which will be explained later in detail with reference to  FIG. 1   d . The support bodies  20  and  22  which are partially closed in the direction of the insert body  18  are of a shape which permits a correspondence with the insert body  18 . 
       FIG. 1   a also shows that several loop packets  26 ,  28  surround a single bushing  14 . It may be provided that the loop packet  26 ,  30  in the installed condition of the joint body  10  in a shaft arrangement is subjected to a tensile force, while the loop packet  28  and a parallel loop packet (not shown in  FIG. 1   a ) embedded in the rubber casing  12  are subjected to a compressive or shearing force, respectively. 
       FIG. 1   b  is a plan view of the elastic joint body  10  according to  FIG. 1   a . Therein, the support arrangement  16  with the insert body  18  and the support body  20  or  22 , respectively, each of which being allocated to a bushing  14  can be seen. The insert body  18  according to this embodiment of the invention comprises a convex centre part which is formed in correspondence with a concave part of the support bodies  20  and  22 . If the loop packet  28  is subjected to a compressive or shearing stress because it is installed in a compression section, the support body  22 , the insert body  18  and the support body  20  will approach each other. Due to the concave shape of the insert body  18 , however, relative movements of these components are possible. This enables the joint body  10  to be adapted to predetermined bending angle requirements in the case of a cardanic load, and rolling by a cooperation of the support bodies  20 ,  22  with the insert body  18  about the centre axis of the joint body is facilitated. 
       FIG. 1   c  is a sectional view along line A-A in  FIG. 1   b  . The insert body  18  comprises reception areas  32  in corner areas for the parallel strands of the loop packet pair  28 ,  34 , with the parallel strands  28   a ,  28   b  of the loop packet  28  being received in upper corner areas and the parallel strands  34   a  and  34   b  of the loop packet  34  in lower corner areas. In contrast, the insert body  36  comprises only two reception areas  38  for the parallel strands  40   a ,  40   b  of the loop packet  40  in a centre portion. As already mentioned above, the loop packet pair  28 ,  34  is subjected to compression or shearing forces, respectively, while the loop packet  40  accommodated in the insert body  36  is subjected to a tensile force and therefore has a larger cross-sectional dimension. 
       FIG. 1   d  is a sectional view along line B-B in  FIG. 1   b  and shows the insert body  18  with the concave centre portion as well as the support bodies  20  and  22 . The support bodies  20  and  22  each comprise an upper guideway  42  and  44  which is formed thereon, which together guide or receive, respectively, the loop packet  28 . In the lower guideways  46 ,  48  of the support bodies  20  and  22 , the loop packet  34  of the loop packet pair  28 ,  34  is likewise guided or received. Between said upper and lower guideways, corresponding centre guideways  50 ,  52  are formed at the support bodies  20 ,  22 . The individual guideways are separated from each other by material webs of the support bodies  20  and  22 , so that the loop packets received therein will not make frictional contact. This may minimize wear due to friction. 
     In this context, the term guideways refers to the portions of the support bodies  20 ,  22  in which the individual loop packets are guided around the bushings  14  and at the same time supported. As previously mentioned, the guideways are separated from each other by material webs which therefore also separate the individual loop packets from each other so that frictional effects between stacked loop packets are prevented. The loop packets in the outer circumferential area of the bushing  14  may be supported by the guideways and their associated material webs. This permits a considerable increase of the load-carrying proportion of the individual loop packets in this region. Furthermore, it becomes obvious that the guideways  42 ,  44 ,  46 ,  48  at the support bodies  20 ,  22  accommodate a loop packet pair  28 ,  34  which is arranged in a compression section, and that the centre guideways  50 ,  52  of the support bodies  20 ,  22  accommodate loop packets  30 ,  40  which are subjected to a tensile force. Thus, the guideways separate differently stressed loop packets from each other. 
     The centre guideway  50  of the support body  20  receives the parallel strands  30   a ,  30   b  of the loop packet  30 , and the guideway  52  of the support body  22  receives the parallel strands  40   a ,  40   b  of the loop packet  40 . Further, the support body  20  is closed in the direction of the insert body  18  so that it also surrounds the strand  30   b  of the loop packet  30 . The same applies to the support body  22  which encompasses the strand  40   a  with a closed side. This closed area of the support bodies  20 ,  22  may be formed in correspondence with the shape of the insert bodies  18 , which enables an advantageous cooperation of these two components. 
     In addition,  FIG. 1   d  illustrates the collars  24  which axially support the loop packets or the support bodies  20 ,  22 , respectively, or which hold them in their predetermined position on the bushing  14 , respectively. 
     In the following, the function of the joint body with an inventive support arrangement  16  will be discussed. The elastic joint body  10  is attached in the known manner at the shaft sections to be connected. As repeatedly mentioned above, the loop packets are subjected to different stresses. In the support arrangement  16  with the insert body  18  and the support bodies  20  and  22  for supporting the loop packet pair  28 ,  34  which is subjected to a compressive force, the support body  22  will approach the insert body  18  due to a compression of the rubber-elastic casing  12  under operating conditions; the same applies to the insert body  18  which approaches the support body  20 . Due to the fact that an elastic joint body  10  is often subjected to a cardanic load in addition to pure torque transmission and therefore exposed to a certain bending angle which occurs because of an offset or a bending angle between the shaft sections to be connected, it is the loop packets at the outer circumference of the joint body  10  which are subjected to higher stresses. According to the invention, the loop packets are, however, also supported by the support arrangement  16  so that their load-carrying proportion is considerably increased. 
     In the following, further embodiments of the invention will be explained with reference to the remaining figures. In order to avoid repetitions and for the sake of simplicity of the description, components with the same effect or similar components will be identified by the same reference numerals as in the first embodiment, which are, however, preceded by a consecutive numeral. 
       FIG. 2   a  shows the inventive joint body  110  with a support arrangement  116  which comprises an insert body  118  and support bodies  120  and  122  which are allocated to corresponding bushings  114 . The embodiment according to  FIGS. 2   a  to  2   d  differs from the first embodiment according to  FIGS. 1   a  to  1   d  merely in that the insert body  118  as well as the two support bodies  120 ,  122  have a shape different from that which was described for the first embodiment. 
     From  FIG. 2   b  it can be seen that the insert body  118  has a wedge shape tapering towards the centre axis M. The support bodies  120  and  122  therefore comprise a matching chamfered shape which permits a correspondence with the insert bodies  118 . The chamfered shape of the support bodies  120 ,  122  and the wedge shape of the insert body  120  may facilitate rolling of the insert body  118  in the axial direction about the centre of the joint body  110 . 
       FIG. 2   c  shows a sectional view along line A-A in  FIG. 2   b . In this case again, reception areas  132  of the insert body  118  for the loop packet pair  128 ,  134  and the insert body  136  with reception areas for the parallel strands  140   a ,  140   b  of the loop packet  140  can be seen. 
     From  FIG. 2   d  it can be seen that contrary to the embodiment according to  FIGS. 1   a to  1   d , the insert body  118  comprises a rectangular wedge shape without bulges in a centre portion. 
       FIG. 3   a  shows a third embodiment of the inventive elastic joint body  210  with the support arrangement  216 . Like the previous embodiments, the support arrangement  216  comprises an insert body  218  as well as support bodies  220 ,  222 . The support bodies  220  and  222  are formed in a round shape matching the bushings  214 , and the insert body  218  is of a corresponding concave shape so that it corresponds to the geometry of the support bodies  220 ,  222 . 
       FIGS. 3   b  to  3   d  illustrate the elastic joint body  210  with the same components as described in the previous embodiments, however provided with the already described support arrangement  216 , whose geometry differs from that of the previous support arrangements. 
       FIG. 4   a  shows the inventive elastic joint body  310  with a support arrangement  316  which, in contrast to the previously described embodiments, is formed by only one insert body  318 . The insert body  318  is arranged between two adjacent bushings  314  and encompasses the loop packet  328  or is penetrated by same, respectively. 
       FIG. 4   b  again is a plan view of the elastic joint body  310  with the insert body  318  which comprises concave bulges so that it corresponds to the geometry of the bushings  314  or to that of the loop packets, respectively, which wrap around the bushings  314 . 
     The sectional view according to  FIG. 4   c  clearly shows that the insert body  318  is penetrated by the parallel strands  328   a ,  328   b  of the loop packet  328  or by the parallel strands  334   a ,  334   b , respectively, of the loop packet  334 . The insert body  336  which accommodates a loop packet  340  with parallel strands  340   a ,  340   b  subjected to a tensile stress, comprises, as already mentioned in the previous embodiment, reception areas  338  in a centre portion for the mentioned parallel strands of the loop packet  340 . 
       FIGS. 5   a  to  5   c  show another embodiment of the present invention, wherein the insert body  418  is provided with groove-like reception areas  432  for the parallel strands  428   a ,  428   b  of the loop packet pair  428 . The insert body  438  installed in the tensile section again comprises reception areas  438  for the parallel strands  440   a ,  440   b  of the loop packet  440  in a centre portion. 
     From  FIGS. 6   a  to  6   c  which illustrate still another embodiment of the invention, it can be seen that the insert body  518  according to this embodiment of the invention is formed with a constriction in the centre and thus slightly narrower, and then slightly broadens towards the end. The corner areas of the insert body  518  comprise reception areas  538  for the parallel strands of the loop packet pair  528 ,  532 . 
     The embodiment according to  FIGS. 7   a  to  7   c  shows an insert body  618  with essentially orthogonally extending surfaces relative to the centre axis M, with which the parallel strands of the loop packet pair  628 ,  634  may come into contact, i. e. the insert body  618  is designed in such a manner that it may be inserted between the parallel strands of the loop packet pair  628  and  634 . The insert body  618  supports the loop packets, in particular, in the case of a cardanic load, and additionally reinforces the elastic joint body. 
     In the following, further constructive design possibilities for a support body will be explained. First, it is to be mentioned that the individual support bodies and the guideways or their portions, respectively, between the various loop packets may be formed larger or stronger, respectively, depending on the torques to be transmitted and the resulting dimensioning of the elastic joint body. This also applies to the already described embodiments. 
       FIGS. 8   a  and  8   b  show a support body  20  with an upper guideway  42  for the loop packet  28 , a lower guideway  46  for guiding the loop packet  30  as well as a centre guideway  50  for loop packet  26 . The support body according to  FIGS. 8   a  and  8   b  is formed so as to be open, i.e., the support body does not completely enclose the loop packets. 
       FIGS. 9   a  and  9   b  show a support body  20  which partially encloses the centre guideway  50  between the loop packet pair  28 ,  30  subjected to a compressive force. At the site where the loop packet subjected to a compressive force exits the bushing  14  arranged in the support body  20 , this loop packet is no longer enclosed. The two loop packets  28  and  34  subjected to a compressive force are not enclosed at all. 
     On the other hand,  FIGS. 10   a  and  10   b  show a support body  20  which partially encompasses the guideways  42 ,  46  and  52  as well as all loop packets  28 ,  30 ,  32  at the outer circumference which wraps around the bushings. 
     With respect to the manufacture of the support arrangement with insert bodies and support bodies, the insert bodies are either placed into a mould and then injection-moulded with a rubber-elastic material, or a skeleton of synthetic material is pre-injected and then coated with a rubber-elastic material. 
     The variety of the embodiments of the invention in general indicates possibilities for the support of the individual loop packets relative to each other, for the prevention of a mutual contact of the loop packets in such areas where relative movements may occur, in particular, in areas close to the bushings, in order to eliminate frictional effects, and for the improvement of the torque-transmitting properties of correspondingly configured joint bodies.