Abstract:
The invention relates to a communication bellows, of the type comprising: at least one external skin ( 22 ) which has a succession of inwardly directed undulations ( 56 ); at least one internal skin ( 24 ) which has a succession of outwardly directed undulations ( 58 ) which are provided facing the inwardly directed undulations ( 56 ) of the external skin ( 22 ), the two skins ( 20, 22 ) together delimiting an acoustic insulation space ( 25 ), the internal skin ( 24 ) being connected to at least some of the inwardly directed undulations ( 56 ) of the external skin ( 22 ), wherein the external skin ( 22 ) and internal skin ( 24 ) are connected to each other only by some mutually facing undulations ( 56, 58 ), other undulations ( 56, 58 ) of the two skins ( 22, 24 ) remaining separate from each other.

Description:
[0001]    Priority is claimed to French Patent Application No. 08 50442 filed on Jan. 24, 2008 which is hereby incorporated by reference herein. 
         [0002]    The present invention relates to a communication bellows for a rail vehicle, of the type comprising: at least one external skin which has a succession of inwardly directed undulations and at least one internal skin which has a succession of outwardly directed undulations which are provided facing the inwardly directed undulations of the external skin. 
       BACKGROUND OF THE INVENTION 
       [0003]    Rail vehicles for the transport of passengers are commonly formed by a succession of cars which communicate with each other. To that end, a communication passage is provided between the adjacent ends of two successive cars. During travel on bends, the communication passage must be able to become deformed. In this manner, it is known to use a bellows whose ends are connected to the successive cars in order to delimit the communication passage. Passengers can then move through the bellows which forms a sealed corridor. 
         [0004]    In high-speed trains, the bellows is constituted by a single thin closed rubber profile-member, the thickness being in the order of 1.5 mm. This bellows is not completely satisfactory from an acoustic point of view. There further exist double-skin bellows, the skins each being constituted by a web covered with rubber. The two skins form successive undulations and have of themselves a bellows-like shape. The two skins are secured together by connections which are provided in the region of all the peaks of the mutually facing undulations of the two skins. 
         [0005]    This solution is also unsatisfactory from an acoustic point of view. 
       SUMMARY OF THE INVENTION 
       [0006]    An object of the invention provides a communication bellows which has good acoustic insulation properties, while at the same time ensuring a large communication width and preserving the capacity thereof for compression and deformation during displacement of the communication means. 
         [0007]    The present invention provides a communication bellows having a closed contour, including at least one external skin which has a succession of inwardly directed undulations and at least one internal skin which has a succession of outwardly directed undulations which are provided facing the inwardly directed undulations of the external skin. The two skins together delimiting an acoustic insulation space, the internal skin being connected to at least some of the inwardly directed undulations of the external skin, wherein the external skin and internal skin are connected to each other only by some mutually facing undulations, other undulations of the two skins remaining separate from each other. 
         [0008]    According to preferred specific embodiments, the communication bellows may include one or more of the following features:
       the inwardly directed and outwardly directed undulations of the external skin and internal skin have peaks which are provided facing each other in the same plane which is transverse relative to the bellows,   the two skins are connected to each other at most at the mutually facing peaks of the inwardly and outwardly directed undulations,   the proportion of mutually facing undulations of the external skin and internal skin which are connected to each other is between 30% and 60% of the total number of mutually facing undulations,   the external skin and internal skin are connected to each other by hinges which extend over the majority of the length of the undulations of the two skins,   the hinges comprise a first assembly of knuckles which are connected to the external skin and a second assembly of knuckles which are connected to the internal skin, the knuckles being interposed and a pin, about which they are each articulated, extending therethrough,   the external skin and internal skin have, along each edge thereof, a fixing rim which protrudes towards the outer side and the inner side of the bellows, respectively,   the fixing rims are secured to the edge of the external skin and internal skin by over-molding,   the external skin and internal skin have the same thickness,   the thickness of the external skin and internal skin is between 3 and 7 mm,   the external skin and internal skin have, along the opposing peripheral edges thereof, assembly flats, along which the two skins are compressed against each other,   the undulations of the external skin and internal skin have a height between 20 and 35 mm, and   the undulations of the external skin and internal skin have, when at rest, a length between 20 and 30 mm.       
 
         [0021]    The invention further provides a communication zone which comprises two end walls of two successive cars of a rail vehicle, each delimiting a passage opening and a communication bellows as defined above, which is connected to the two walls between the two passage openings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The invention will be better understood from a reading of the following description which is given purely by way of example with reference to the drawings, in which: 
           [0023]      FIG. 1  is a perspective view of the communication zone between two cars, showing the communication bellows according to the invention; 
           [0024]      FIG. 2  is a longitudinal section of the communication zone between two cars, showing the communication bellows according to the invention; 
           [0025]      FIG. 3  is a partial section, drawn to an enlarged scale, of the communication bellows in the rest state, i.e., without any axial load; 
           [0026]      FIG. 4  is a perspective view of two flanges for retaining the ends of the communication bellows; 
           [0027]      FIG. 5  is a view which is identical to that of  FIG. 3 , the communication bellows being in its compressed state; and 
           [0028]      FIG. 6  is a view which is identical to that of  FIG. 3 , the communication bellows being in its extended state. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]    The communication zone  10  illustrated in  FIG. 1  is that of a train which includes high-speed rail cars which are assembled together. Such a communication zone exists between each pair of successive cars. In this manner, it comprises two walls  12 ,  14  which are provided at the ends of the two cars. Two openings  16 ,  18  are delimited through the facing walls  12 ,  14  for movement of passengers. Those openings are generally rectangular, the long side being arranged vertically. 
         [0030]    A bellows  20  according to the invention is arranged between the two openings. It is connected at each of its ends to the end walls  12 ,  14  and forms therewith the communication zone  10 . 
         [0031]    The bellows forms a closed contour and in this manner delimits an enclosed conduit which allows movement of passengers. When viewed in section, it generally has a shape which is substantially identical to that of the openings  12 ,  14  in continuation of which it is installed. 
         [0032]    As illustrated in  FIGS. 2 and 3 , the bellows comprises an external skin  22  and an internal skin  24 , both undulating and being connected to each other by peripheral connections which are longitudinally spaced apart from each other. The two skins together delimit an acoustic insulation space  25  which is mainly enclosed. 
         [0033]    The external skin  22  and internal skin  24  have at the two ends thereof peripheral rims  26 ,  28  which extend outwardly and inwardly relative to the bellows itself, respectively. The rims are provided in the same plane and are opposite each other. They are each formed at the end of a flat peripheral edge  30 ,  32  which is provided at each end of the two skins. Those flat peripheral edges  30 ,  32  are kept secured to each other and together form a cylindrical web  34  of the bellows which extends in the central portion of the thickness thereof in a centre plane P. In this manner, the two rims  26 ,  28  together form a connection shoulder  36  which protrudes radially at one side and the other of the web  34 . 
         [0034]    The fixing rims  26 ,  28  are preferably fitted to the edge of the external skin  22  and internal skin  24  by over-molding. 
         [0035]    In order to connect the bellows, the connection shoulders  36  are each gripped between two connection flanges. The flange designated  38  is fixedly joined to each end wall  12 ,  14  and the other flange designated  40 A,  40 B is fitted to the associated end wall. 
         [0036]    As illustrated in  FIG. 2 , the flanges  38  delimit a peripheral channel  42  which is intended for receiving the rim  26  and the opening of which is directed inwards. 
         [0037]    The flanges which are designated  40 A,  40 B and which are only illustrated in  FIG. 4 , comprise a peripheral channel  44 , the opening of which is directed outwards. Each channel  44  is capable of receiving a rim  28 . 
         [0038]    The channel  44  is fixedly joined to an adjacent peripheral fixing ring  46  which bounds the channel  44  over the entire length thereof. The fixing ring  46  is perforated with holes which are regularly distributed over its length and through which assembly screws  48  which are screwed into the flanges  38  are engaged. 
         [0039]    Whereas the flange  40 A forms a closed contour, the flange  40 B is interrupted along a lower side in order to allow the introduction of a threshold  50  which is visible in  FIG. 1  and which ensures the retention of the bellows in that zone. To that end, the threshold delimits a channel for receiving the rim  28 . 
         [0040]    As illustrated in  FIG. 3 , the external skin  22  and internal skin  24  each has, in the central portion over the majority of the length thereof between the edges  32 ,  34 , undulating zones  52 ,  54  which are formed by successive undulations  56 ,  58 . Those undulations  56 ,  58  are displaced opposite each other at one side and the other of the centre plane P of the thickness of the bellows. In this manner, they generally extend outwards and inwards relative to the rims  26 ,  28 . 
         [0041]    The two skins  22 ,  24  have the same number of undulations  56 ,  58  and, when viewed in section, are mutually symmetrical relative to the centre plane P. 
         [0042]    The undulations of the undulating zones  52 ,  54  are periodic and are substantially sinusoidal. The number of undulations is between 8 and 15 and is, for example, 11. 
         [0043]    In this manner, the inwardly directed undulations  56  and outwardly directed undulations  58  of the undulating zones of the external skin  22  and internal skin  24  have peaks  60 ,  62  which are provided facing each other in the same plane which is transverse relative to the bellows, respectively. 
         [0044]    The undulating zones  52 ,  54  of the two skins are connected to each other at most in the region of some mutually facing peaks  60 ,  62  of the inwardly directed and outwardly directed undulations. In this manner, the external skin  22  and internal skin  24  are connected to each other only at some peaks  60 ,  62  of mutually facing undulations, the other undulations of the two skins remaining separate and free with respect to each other. 
         [0045]    In this manner, for example, approximately one peak  60  out of two is connected to the peak  62  of the other facing skin over the length of the bellows. 
         [0046]    Preferably, the proportion of mutually facing undulations which are connected to each other is between 30% and 60%, and is preferably substantially 40% of the mutually facing undulations, and in this manner from 40% to 70% of the mutually facing undulations are not connected. 
         [0047]    The external skin  22  and internal skin  24  are connected to each other by hinges  64  which extend over the majority of the length of the peaks of the mutually facing undulations. 
         [0048]    To that end, the hinges comprise a first assembly of knuckles  66  which are connected to the external skin  22  and a second assembly of knuckles  68  which are connected to the internal skin  24 . The knuckles  66 ,  68  are interposed and are articulated about a common pin  70  which extends over the entire length of the hinge and which is engaged through the successive knuckles  66 ,  68 . 
         [0049]    The external skin  22  and internal skin  24  have the same thickness. Preferably, the thickness of undulating zones  52 ,  54  of the external skin  22  and internal skin  24  is between 3 and 7 mm. It is preferably substantially 4.5 mm. The two skins are self-supporting and are formed by a suitable rubber material. The skins comprise only rubber and do not comprise any fabrics, or any other matrix, for supporting the rubber. 
         [0050]    The undulations have a height which is between 20 and 35 mm and preferably substantially 27 mm. The undulations have, when at rest, a length which is between 20 and 30 mm. 
         [0051]    In this manner, the undulating zones  52 ,  54  of the bellows have, when at rest, a length which is substantially, for example, 258 mm, this being reduced to, for example, 190 mm when the bellows is in its compressed state as illustrated in  FIG. 5 , and increasing to, for example, 410 mm when the bellows is in its extended state as illustrated in  FIG. 6 . 
         [0052]    Owing to its double skin, the bellows can be inflated during assembly in order to reach its positioning dimension and to facilitate assembly. Placement in a mold in order to form the definitive bellows from the extruded rubber profile which forms the undulating zones  52 ,  54  allows integration of an operation for adding a different material to the periphery of the bellows which forms the connection shoulder  36 , having a hardness and shape suitable for improving the sealing of the assembly at the ends of the cars. 
         [0053]    Since the number of connections between the two skins is smaller, the disadvantageous effect thereof from the point of view of acoustic insulation may be reduced while allowing good cohesion of the bellows for traveling on bends and resistance to loads owing to pressure waves.