Abstract:
The present invention relates to a weighing module for measuring wheel contact forces of rail-bound vehicles, comprising a measuring rail and a number of strain gauges, wherein the strain gauges are applied directly on the measuring rail. The measuring rail comprises a load introduction region, made of at least one load introduction part, and at least two deformation bodies, which are connected fixedly in each case to a load output plate and, via a hinge, to the load introduction region. The strain gauges are arranged on the deformation bodies and capture the shear strain acting between the hinges and load output plates.

Description:
[0001]    This nonprovisional application is a continuation of International Application No. PCT/EP2011/004907, which was filed on Sep. 30, 2011, and which claims priority to German Patent Application No. DE 10 2010 047 234.4, which was filed in Germany on Oct. 4, 2010, and which are both herein incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a weighing module for measuring wheel contact forces of rail-borne vehicles. 
         [0004]    2. Description of the Background Art 
         [0005]    To measure wheel contact forces on rail vehicles, a suitable force measuring device is required for each wheel, which is to say a weighing apparatus is required that is built into a special measuring track. Inserted in appropriate positions in the rails of a measuring track are measuring bridges to which weighing sensors are attached. These weighing sensors generally are supported on special foundation plates that are intended to ensure a rigid connection to the track substructure into which the absorbed forces are conducted. 
         [0006]    Because of the installation space required or the installation height of such an external measuring device, it is often necessary to make structural adaptations to the foundation. In particular for existing track installations that are to be retrofitted with such a weighing technology, suitable modifications are not feasible. 
         [0007]    As a result of the attachment of the weighing sensors to a measuring bridge, which generally is accomplished by means of screw fittings, the measurement system has its own disturbing influence, which causes measurement errors in the force being ascertained. Consequently, calibration is always necessary in conventional measuring devices for wheel contact forces in order to be able to ascertain the precise properties of the measuring device. 
       SUMMARY OF THE INVENTION 
       [0008]    It is therefore an object of the invention to provide a measuring device, having a measuring bridge and weighing sensors, for measuring wheel contact forces that does not require any adaptations to the track substructure, but instead can be attached directly to an existing rail mount, e.g. to ribbed plates. 
         [0009]    According to an embodiment of the invention, a weighing module for measuring wheel contact forces of rail-borne vehicles is proposed that comprises a measuring rail and a number of strain gauges that are applied directly to the measuring rail. The measuring rail, in turn, has a load introduction region that is composed of at least one load introduction part and at least two deformation bodies. The deformation bodies are rigidly connected (which is to say statically) to one load exit plate each, and are connected to the load introduction region by one link each. The strain gauges are arranged on the deformation bodies and sense the shear strains acting between the links and the load exit plates. 
         [0010]    The measuring rail according to an embodiment of the invention, with the strain gauges applied directly to the rail body, constitutes a compact, one-piece, and hence standalone, weighing module. An especially advantageous feature of such a one-piece construction is that it is possible to forego the calibration that is required in prior art measuring bridges with externally screw-mounted weighing sensors. The precision with which the manufacture is determined thus corresponds to the precision of the weighing module in the installed state. 
         [0011]    The one-piece measuring rail according to an embodiment of the invention can be made from a rail profile that includes at least a rail head and a rail web. In ideal fashion, the profile of the measuring rail can correspond to the profile of the railway tracks within which one measuring rail or multiple measuring rails is/are to be installed in order to provide a measuring section. Consequently, a measuring rail can also be made from a full rail profile. Thus, in order to provide a measuring section it is only necessary to install the measuring rail in place of the rail of an existing track, which is to say a railway track, or replace the railway tracks with a number of measuring rails. As a general rule, therefore, other common or application-specific rail profile types also come into consideration for a given measuring rail. 
         [0012]    An active shear strain region of the deformation body can be formed between the links and the load exit plates. Pockets for accommodating the strain gauges can be provided in the shear strain regions. 
         [0013]    In addition, the deformation bodies can have a bevel on a lateral side of the measuring rail for connecting a neighboring rail, which bevel is suitable for routing an electrical contact for the strain gauges. 
         [0014]    According to an embodiment, the measuring rail of a weighing module according to the invention can have two deformation bodies. Each of the links thus is preferably arranged at one of the two ends of the measuring rail. As a result, the load introduction part then extends over the entire length of the measuring rail and forms the active measuring section of the weighing module. 
         [0015]    As a result of this special design, it is possible for the change in length of the load introduction part arising in the case of bending due to a high weight loading to have only a minor influence on the deformation bodies and thus only a minor influence on the measurement result. 
         [0016]    The measuring rail can be constructed with mirror-image symmetry in its longitudinal direction, so that the load introduction part is supported symmetrically by the two links on the two deformation bodies. 
         [0017]    The geometry of the measuring rail thus makes it possible for the wheel contact force to always be introduced through the two links into the two deformation bodies, regardless of the position that a wheel being tested assumes on the measuring rail. Another advantage is in that the tensile forces that arise during driving can be transmitted to the deformation bodies and sensed by the strain gauges&#39;. 
         [0018]    If a number of strain gauges with which a complete Wheatstone measuring bridge can be implemented are arranged on each deformation body, then in the case of weighing modules with symmetrically arranged deformation bodies, wheel positions on a given weighing module can additionally be determined, and consequently axle bases, as well. 
         [0019]    An alternative form of the weighing module according to an embodiment of the invention can comprise a measuring rail with at least three load introduction parts and the same number of deformation bodies. The measuring rail additionally comprises a seat and a connector, wherein the connector is designed to be brought into engagement with a seat of a measuring rail of another weighing module. 
         [0020]    In consequence, a relatively long measuring section can be assembled very simply from a number of such weighing modules that preferably also have been produced as a single piece. 
         [0021]    In each case, one outer load introduction part of the measuring rails is supported only on a deformation body of the same measuring rail. During construction of a measuring section, this load introduction part is then preferably supported on the deformation body of another, i.e., neighboring, weighing module. This support is achieved through the paired seats and connectors of the measuring rails of neighboring weighing modules that are introduced into the rail body. 
         [0022]    Thus, once again the wheel contact force can be introduced through the two links into two deformation bodies, generally by one load introduction part in each case, regardless of the position that a wheel being tested assumes on the measuring rail, and in addition the tensile forces that arise during driving are transmitted to the deformation bodies and consequently can be sensed by the strain gauges. 
         [0023]    Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein: 
           [0025]      FIG. 1  is a side or longitudinal view of a weighing module with a measuring rail made from a full rail profile; 
           [0026]      FIG. 2  is a perspective view of a weighing module made from a full rail profile with tongue and groove for connection to spacers; 
           [0027]      FIG. 3  is a perspective view of a spacer for a measuring rail as shown in  FIG. 2 ; 
           [0028]      FIG. 4  is a measuring track with three weighing modules connected to one another by spacers; 
           [0029]      FIG. 5  is a side or longitudinal view of a weighing module with a measuring rail made from a rail profile with no rail foot; 
           [0030]      FIG. 6  is a perspective view of a weighing module with a measuring rail made from a rail profile with three deformation bodies; 
           [0031]      FIG. 7  is a measuring track with three connected weighing modules as in  FIG. 6 ; 
           [0032]      FIG. 8  is a measuring track with three connected weighing modules as in  FIG. 7  and end pieces located on both sides; 
           [0033]      FIG. 9  is an embodiment of an end piece for a measuring track from  FIG. 8 ; 
           [0034]      FIG. 10  is a second embodiment of an end piece for a measuring track from  FIG. 8 ; and 
           [0035]      FIG. 11  is a cutaway view of the weighing module from  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION 
       [0036]    Before the figures are discussed in detail, it should be noted that  FIGS. 1 ,  2 ,  4 ,  5  and  11  show a first group of weighing modules according to an exemplary embodiment of the invention, each of which has two symmetrically arranged measuring points. These embodiments can be built directly into a separate track, for example, and can measure the wheel contact force of a wheel.  FIGS. 6 ,  7 , and  8  show a second group of exemplary embodiments of weighing modules according to the invention that have at least three measuring points. It is especially simple to arrange any number of such weighing modules in a row. 
         [0037]    In addition, corresponding reference numbers appearing in the figures refer to components that are identical or function identically. 
         [0038]    Shown in  FIG. 1  is a first exemplary embodiment of a weighing module according to the invention for measuring wheel contact forces of rail-borne vehicles. This weighing module comprises essentially the body of a measuring rail  1 , to which are applied a number of strain gauges  2 . The base body of the measuring rail shown can be composed of a construction rail profile of type Vo 1-54, for example, although other common or application-specific rail profiles also come into consideration as the base body for a particular measuring rail as a general rule. 
         [0039]    The measuring section, within which the wheel contact forces of a rail-borne vehicle can be sensed, includes essentially the entire length of the measuring rail  1  shown. The head  7  and the web  8  of the measuring rail have approximately the same width in profile, so that the rail head  7  and the rail web  8  transition smoothly into one another along the rail height. A rail foot  9  is provided at the bottom of the profile. As already mentioned at the outset, other rail profiles also come into consideration. 
         [0040]    The measuring rail  1  is structured in the region of the rail web  8  and rail foot  9  by means of two slots  10  that pierce the body of the rail profile in its width. Starting from a bore  11  that is located at a defined distance from one of the opposite rail ends, each of the two slots extends in the longitudinal direction of the measuring rail, first horizontally toward the center of the rail and, after a defined distance, inclined at an angle toward the rail foot  9 . Moreover, a link  6  is defined in each case by this defined distance. 
         [0041]    A suitable structuring can be accomplished by means of metal-cutting production, for example. 
         [0042]    A measuring rail  1  structured in such a manner thus forms a load introduction region with a load introduction part  3 , two deformation bodies  4 , and two links  6 . Accordingly, the links  6  are located at each end of the measuring rail  1 , so that one of the links  6  connects the load introduction part  3  to one of the two deformation bodies  4  in each case. Provided under each of the deformation bodies  4  is a load exit plate  5  with which the measuring rail  1  can be rigidly attached to a substructure  12 , e.g., a concrete foundation. 
         [0043]    The load exit plates  5  preferably are rigidly connected to the relevant deformation body  4 , wherein this connection can take place, for example, by means of thermal joining or through a screw connection that is not shown. As a general rule, a unit having a measuring rail  1  and load exit plate  5  can also be produced from a one-piece base body. Likewise, the load exit plates  5  can also be part of a rail mount, e.g., a ribbed plate, so that the rigid connection for rail mounting can be accomplished by means of external clamps. 
         [0044]    The load introduction part  3  extends in the longitudinal direction over the entire length of the measuring rail  1  and has the full height of the rail profile in the region located between the two deformation bodies  4 , and is supported via the two links  6  on the two deformation bodies  4  and on the load exit plates  5  located thereunder. 
         [0045]    Regardless of the position on the rail head  7  at which the contact force of a wheel is introduced into the load introduction part  3 , the force is always transmitted into the deformation bodies  4  through the links  6 . As a result of the arrangement of the links  6  according to the invention, an exact force transmission is achieved, wherein, in particular, the influence on the two deformation bodies  4 , and hence on the measurement result as well, of changes in length of the load introduction part  3  that can arise in the case of bending due to a high weight loading is reduced. Furthermore, the arrangement of the links  6  according to the invention permits the transmission and measurement of tensile forces that arise during driving on the measuring rail  1 . 
         [0046]    The two deformation bodies  4  are designed such that the shear stresses caused by forces transmitted through the two links into the two deformation bodies  4  can be sensed between the links  6  and the load exit plates  5  located under the rail foot  9  by means of strain gauges  2 . 
         [0047]    A number of strain gauges are located on each deformation body, with which a complete Wheatstone measuring bridge, and thus a measuring point, can be implemented at each deformation body. 
         [0048]    Two strain gauges  2  with two resistance regions each are arranged in each deformation body  4 , as described below. A measuring point is defined in each case by such an arrangement of two strain gauges  2  in each deformation body  4 . 
         [0049]    As is evident from  FIG. 1 , the two links  6  are each arranged at one end of the measuring rail  1  for the purpose of load or force transmission. The load exit plates  5  are offset in the longitudinal direction toward the rail ends, so that an active deformation region is produced in the two deformation bodies  4  in the longitudinal direction between the relevant link  6  and the side of a load exit plate  5  facing the relevant rail end. In order to guarantee an optimal deformation, the rail foot of the rail profile that is shown by way of example has been removed in the regions between the rail ends and deformation bodies  4 . 
         [0050]    As is also readily evident in  FIG. 1  and in particular in  FIG. 11 , which shows a cutaway view of another embodiment, the strain gauges  2  that are used for measurement of the shear strains in the deformation bodies  4  preferably are each located in a pocket  13 , which can be introduced laterally into the relevant deformation body  4 , for example in the form of a blind hole. The pockets  13  serve to accommodate the strain gauges  2 , and are each located in the shear strain region of a deformation body  4 . 
         [0051]    Each deformation body can have two pockets  13  separated from one another by a web  19 , as can be seen in  FIG. 11  in particular, wherein either two strain gauges, or preferably one strain gauge with two resistance regions, i.e. a double strain gauge, are in turn located in each pocket. Moreover, regardless of whether two strain gauges with one resistance region each or one strain gauge with two resistance regions are placed in each pocket, the resistance regions of the strain gauges, which are not shown in detail in the figures, usefully are also oriented at a 45° angle to one another within a given pocket  13  of a deformation body  4 , e.g., as two serpentine regions oriented at a 45° angle to one another, so that shear stresses and/or displacement angles can also be calculated from the measured elongations. Such an orientation can in general be considerably simplified by the use of suitably prefabricated double strain gauges. 
         [0052]    The bottom edges of the longitudinal sides of the measuring rail shown in  FIG. 1 , as well as the measuring rails shown in  FIGS. 2 ,  4 ,  5  and  11 , are each provided with a bevel, for example a 45° bevel  14 . As is evident in particular from  FIGS. 2 and 11 , this bevel  14  is suitable for routing electrical connections for contacting the strain gauges located in the pockets  13 . In the installed state, both sides of the measuring rail are abutted by, e.g., additional measuring rails next to it or, in an alternative, the rails of a relevant track, also called railway tracks, wherein at most a small gap between the measuring rail and railway track is permissible. By means of the bore  15  shown in  FIGS. 2 and 11 , the electrical connections of the strain gauges can be routed out of the relevant pockets  13 . As a result of the bevel  14 , there is sufficient spacing to an additional, abutting measuring rail—not shown in  FIGS. 1 ,  2 ,  5  and  11 —or alternative adjacent rail of a track, to lead out a suitable cable. Such a sufficient spacing is readily apparent in the row arrangement of a preferred refinement shown in  FIG. 4 , for example. 
         [0053]      FIGS. 2 and 11  show such an embodiment of a weighing module according to the invention, wherein  FIG. 11  is a cutaway view of the weighing module from  FIG. 2 . A measuring rail  16  shown there differs from the measuring rail  1  from  FIG. 1 . Nonetheless, the measuring rail  16 , like the embodiment described above with reference to  FIG. 1 , includes a construction rail profile from whose rail body, in particular in the region of the web  8 , are formed two links  6 , two deformation bodies  4  that each have two pockets  13  for accommodating a number of strain gauges—not shown in detail—to provide one measuring point for each deformation body, and a load introduction part  3 . 
         [0054]    In contrast to the weighing module shown in  FIG. 1 , the measuring rail  16  of the weighing module shown in  FIGS. 2 and 11  has a connector at each of its two ends, each of which has a groove  17  and a tongue  18 . Using the connector shown and a suitably matched spacer  19 , one embodiment of which is shown in  FIG. 3  by way of example, multiple measuring rails  16  can be brought into engagement with one another in an extremely simple manner such that a measuring track can be constructed with any desired length, as shown in  FIG. 4 , for example. 
         [0055]      FIG. 3  shows one embodiment of an appropriate spacer  19 , which like the measuring rail  16  preferably is made from a construction profile or full rail profile, wherein a connector of complementary design to the measuring rail  16  having a tongue  32  and groove  31  is provided at its ends. The measuring rail  16  and the spacer  19  thus provide a connecting system with which it is especially easy to assemble a measuring track of any desired length for later installation in an existing track system. 
         [0056]    The rails of an existing track, which is to say the railway tracks, need only be removed over the length of a desired measuring track and replaced with a number of measuring rails  16  and spacers  19 . 
         [0057]    As already mentioned,  FIG. 4  shows by way of example a measuring track comprising three measuring rails  16 , wherein each pair of measuring rails  16  is connected by a spacer  19 . The measuring track can be terminated at each of the first and last measuring rails with an end piece, not shown in the Figures, that ensures an essentially joint-free transition to the railway tracks adjacent thereto. 
         [0058]      FIG. 5  shows an alternative embodiment of a weighing module according to the invention in which, in contrast to the embodiments described above, a rail profile with no rail foot is used instead of a full rail profile as the base body for the measuring rail  20  employed there. Such an embodiment can be used when the material properties of a full rail cannot be employed for measurement reasons, for example. 
         [0059]    All in all, therefore,  FIGS. 1 ,  2 ,  4 ,  5  and  11  show weighing modules according to an exemplary embodiment of the invention, each of which has two symmetrically arranged measuring points, wherein these embodiments can be placed, e.g., directly in a separated track to ascertain the wheel contact force of a wheel. As a result of specially designed connectors that are secured between at least two weighing modules, measuring sections of any desired length can be constructed, for example measuring sections as in  FIG. 4  using connectors as in  FIG. 3  for weighing modules as in  FIG. 2 . However, in the case of relatively low maximum wheel loads, including in the case of streetcars for example, the connectors themselves can also be elongated in such a manner that one can construct a measuring section of equal length with fewer measuring points. 
         [0060]    Furthermore, using weighing modules with symmetrically arranged measuring points, it is possible to ascertain positions of a wheel on a relevant weighing module, and thus to ascertain axle bases as well. 
         [0061]      FIG. 6  shows another embodiment of the invention. For example, the measuring rail  21  shown there can be produced from a profile without a rail foot as shown, and comprises a load introduction region made up of at least three load introduction parts  22 ,  23 ,  24 , wherein the at least three load introduction parts  22 ,  23 ,  24  as a whole are connected by an equal number of links  6  to an equal number of deformation bodies  25 ,  26 ,  27 . In this design, all deformation bodies extend in the same direction and are consequently aligned with one another so that in each case an outside load introduction part  24  is supported only on one deformation body  27 . In the example shown, the measuring rail  21  has three load introduction parts  22 ,  23 ,  24 , three links  6 , and three deformation bodies  25 ,  26 ,  27 , each of which again has two pockets for accommodating strain gauges. Such a measuring rail thus defines three measuring points. The measuring rail  21  can be made from the base body of a rail profile or any other semifinished product, for example by metal-cutting methods, wherein the load exit plates  5  can likewise constitute a one-piece unit with the deformation bodies  25 ,  26 ,  27 . 
         [0062]    The ends of the measuring rail  21  have a seat surface  28  and connecting surface  29 , which are shaped such that a number of individual measuring rails can be arranged in a row and brought into engagement with one another so that measuring tracks with a specific required or desired length can be assembled. A corresponding measuring track with three measuring rails  21 ,  21   a  and  21   b  is shown by way of example in  FIG. 7 . In a manner similar to the preceding embodiments, suitably matched end pieces that ensure an essentially joint-free transition to the railway tracks adjacent thereto can be provided for terminating the measuring track. A suitably terminated measuring track with three measuring rails  21 ,  21   a  and  21   b  as in  FIG. 7  is shown in  FIG. 8  by way of example. 
         [0063]    Each load introduction region of each measuring rail  21 ,  21   a  or  21   b  forms three load introduction parts  22 ,  23 ,  24 , wherein in each case only two load introduction parts  22  and  23  of each measuring rail are supported on two adjoining deformation bodies of the same measuring rail. 
         [0064]    As is evident from  FIGS. 7 and 8 , one outer load introduction part  24  of each measuring rail  21 ,  21   a , and  21   b , which in  FIG. 7  is always the right-hand load introduction part, is supported on the one hand on the deformation body  27  of the same measuring rail  21 ,  21   a  or  21   b , while the opposite side of the load introduction part  24  of the measuring rail  21  is supported via the connecting surface  29  of the measuring rail  21  on the seat surface  28  and deformation body  25  of the measuring rail  21   a . In a corresponding manner, the opposite side of the load introduction part  24  of the measuring rail  21   a  is supported via the connecting surface  29  of the measuring rail  21   a  on the seat surface  28  and deformation body  25  of the measuring rail  21   b.    
         [0065]    Accordingly, support for the load introduction part  24  of the measuring rail  21   b  is provided by the connecting surface  29  of the same measuring rail  21   b , wherein preferably a suitably adapted end piece or terminating piece  31 , such as can be seen in  FIG. 8 , can be provided. The end piece or terminating piece  31  used in  FIG. 8  is shown enlarged in  FIG. 9 . Such a piece is further adapted to substantially simultaneously allow a transition to a railway track, not shown in  FIGS. 7 and 8 , adjoining the end of the measuring track. In the simplest case, this can be accomplished by means of a flat terminating surface  31   b , as can be seen in  FIG. 9 . 
         [0066]    An appropriately adapted end piece or terminating piece  30 , such as can be seen in  FIG. 8 , can be provided for the seat surface  28  of the measuring rail  21  located at the opposite end of the measuring track. The end piece or terminating piece  30  used in  FIG. 8  is shown enlarged in  FIG. 10 . Such a piece is suitably further adapted to simultaneously allow a transition to a railway track, not shown in  FIGS. 7 and 8 , adjoining this end of the measuring track. In the simplest case, this can in turn be accomplished by means of a flat terminating surface  30   b , as can be seen in  FIG. 10 . 
         [0067]    Thus, once again the wheel contact force can generally be introduced by one load introduction part into two deformation bodies through two links in each case, regardless of the position that a wheel being tested assumes on the measuring rail, and in addition the tensile forces that arise during driving are transmitted to the deformation bodies and consequently are sensed by the strain gauges. 
         [0068]    The embodiments of weighing modules according to the invention shown in  FIGS. 7 and 8  thus each have at least three measuring points. Any desired number of such weighing modules can be arranged in a row. Only the beginning and end pieces, which is to say the transitions to the normal track, need to be implemented in an appropriately adapted manner, for example as shown in  FIGS. 9 and 10 . The spacing from support point to support point remains constant and can be adapted to the requirements (e.g., sleeper spacing). 
         [0069]    The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.