Patent Publication Number: US-2019178273-A1

Title: Railway vehicle body and associated method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. non-provisional application claiming the benefit of French Application No. 17 62075, filed on Dec. 13, 2017, which is incorporated herein by reference in its entirety. 
     FIELD 
     The present invention relates to a railway vehicle body, the body being of the type comprising at least one floor module, at least one wall module and at least one roof module, the modules being connected to one another by rivets. 
     The invention also relates to a method for manufacturing the body. 
     The invention more particularly applies to railway vehicle bodies of the tram, subway, interregional train and similar type. 
     BACKGROUND 
     Railway vehicle bodies are known comprising one or several wall modules, one or several floor modules and one or several roof modules. 
     During the assembly of the body, these modules are connected to one another for example by welding. 
     However, assembly by welding may cause a deformation of the modules and thus make the assembly process of such bodies difficult. 
     To avoid a deformation of the body during assembly, it is further known to connect modules by riveting. 
     However, a very large number of rivets, for example two thousand, is necessary to provide a rigid and reliable connection between the modules. This results in a high weight of the body of the railway vehicle and makes the assembly of the body complicated and expensive. 
     SUMMARY 
     One aim of the invention is to reduce the number of rivets, while guaranteeing a rigid and safe connection between the modules. 
     To that end, the invention relates to a railway vehicle body of the aforementioned type, wherein the rivets comprise lower rivets connecting the or each wall module to the or each floor module, the lower rivets comprising at least one group of stiffening rivets, the or each group of stiffening rivets including at least three stiffening rivets that are all arranged along a curve formed in a plane perpendicular to a transverse direction of the railway vehicle body, the curve being continuously differentiable, provided with no inflection point, and having a first end with a first tangent and a second end with a second tangent, said first and second tangents forming an angle between them smaller than or equal to 90°. 
     According to specific embodiments of the invention, the railway vehicle body also has one or more of the following features, considered alone or according to any technically possible combination(s):
         the curve is in an arc of circle shape;   the or each group of stiffening rivets includes at least four stiffening rivets;   for the or each group of stiffening rivets, the stiffening rivets of said group are arranged based on a distribution of the mechanical torsion stresses in each wall module;   the stiffening rivets are arranged in regions of the railway vehicle body concentrating torques around axes transverse to a longitudinal direction of the railway vehicle body;   the or each wall module comprises at least one upright, at least one group of stiffening rivets being arranged at a lower end of the or each upright;   for the or each group of stiffening rivets, the diameter of each stiffening rivet of said group is equal to the diameter of each other stiffening rivet of said group;   the rivets comprise upper rivets connecting the or each wall module to the or each roof module, said upper rivets comprising groups of linear rivets, each group comprising at least three upper rivets aligned with one another;   at least one of the modules from among the floor, wall and roof modules is made up of a pre-equipped module; and   the modules are electrically connected to one another by connectors.       

     The invention also relates to a method for manufacturing a railway vehicle body, the railway vehicle body comprising at least one floor module, at least one wall module and at least one roof module, the method comprising the following steps:
         designing a model for the railway vehicle body, applying static and/or dynamic loads on this model of the railway vehicle body in order to calculate the resultant stresses; and   producing the railway vehicle body, the railway vehicle body being assembled by fixing floor, wall and roof modules to one another by rivets, the rivets comprising lower rivets connecting the or each wall module to the or each floor module, the lower rivets comprising at least one group of stiffening rivets including at least three stiffening rivets arranged based on the distribution in the railway vehicle body of the stresses calculated during the design step.       

     According to one particular embodiment of the invention, the method for manufacturing the railway vehicle body also has the following feature:
         the model designed during the design step is a computer model, the method comprising, between the design and production steps, an intermediate step for validating the railway vehicle body through tests, during which a physical model of the railway vehicle body is at least partially assembled and stresses resulting from static and/or dynamic loads applied in said physical model are measured, at an interface between the or each wall module and the or each floor module, in order to validate the distribution of rivets and in [which], during the production step, the stiffening rivets are arranged based on results of the validation step.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features and advantages of the invention will appear upon reading the following detailed description, provided solely as an example and done in reference to the appended drawings, in which: 
         FIG. 1  is an exploded perspective view of a railway vehicle body according to the invention; 
         FIG. 2  is a side view of the railway vehicle body of  FIG. 1 , shown deformed to illustrate the stresses to which the railway vehicle body is subjected during the application on the latter of static and dynamic loads; and 
         FIG. 3  is a side view of a detail of a junction of a wall module to a floor module belonging to the railway vehicle body of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     In the description, the terms “over”, “under”, “above”, “below”, “upper” and “lower” are defined relative to an elevation direction of a railway vehicle when it is arranged on rails, i.e., a substantially vertical direction when the train is traveling on horizontal rails. The longitudinal direction is defined by the direction of travel of the railway vehicle and the transverse direction is the direction substantially perpendicular to the longitudinal direction and the elevation direction of the railway vehicle. 
     The railway vehicle body  1  shown in  FIG. 1  comprises a floor module  10 , wall modules  12 , end modules  14  and a roof module  16 . It will be noted that in  FIG. 1 , only the wall modules  12  on a first side of the floor  10  and roof  16  modules, and a single end module  14  arranged at a first longitudinal end of the floor  10  and roof  16  modules, are shown; nevertheless, the body  1  also comprises other wall modules  12 , not shown, arranged symmetrically to the wall modules  12  visible on the side opposite the modules  10  and  16 , and another end module  14 , also not shown, arranged at a second longitudinal end of the floor  10  and roof  16  modules opposite the first end. 
     Alternatively, the body  1  comprises, on each side of the floor  10  and roof  16  modules, a single wall module  12 . 
     The floor  10 , wall  12 , end  14  and roof  16  modules delimit an interior space  18  inside the body  1  intended to receive occupants of the railway vehicle and/or equipment. 
     In one example, the modules  10 ,  12 ,  14 ,  16  comprise electronic devices, not shown. The floor  10 , wall  12 , end  14  and roof  16  modules are for example electrically connected to one another by connectors, not shown. 
     Preferably, the floor  10 , wall  12 , end  14  and roof  16  modules are pre-equipped modules. 
     Alternatively, only one module from among the modules  10 ,  12 ,  14  and  16  is a pre-equipped module. 
     “Pre-equipped module” refers to a module comprising components assembled before the assembly of the module to the other modules of the body  1 . 
     A pre-equipped module is for example configured to be inspected individually with an inspection station provided to that end, at which the installation and/or the correct operation of components and/or electronic devices of said pre-equipped module is for example inspected. 
     The floor module  10  extends in a horizontal plane. The floor module  10  is arranged below the roof module  16  and is substantially perpendicular to the wall  12  and end  14  modules. 
     The floor module  10  for example comprises a metal structure configured to bear the weight of the occupants or equipment, not shown, of the railway vehicle. The floor module  10  further comprises a floor for example made from wood or composite or multiple materials attached on an upper face of the structure. The floor typically makes up a floor intended to receive occupants of the railway vehicle and/or equipment of the railway vehicle. 
     The floor module  10  is connected to the wall modules  12  and the end module  14 . Each wall module  12  extends in a vertical plane, perpendicular to the transverse direction. A first part of the wall modules  12  together form a first side wall of the body  1  and a second part of the wall modules  12  together form a second side wall of the body  1 , said first and second side walls delimiting the interior space  18  transversely. 
     As shown in particular in  FIG. 2 , each wall module  12  comprises a support structure comprising uprights  20  each connecting the floor module  10  to the roof module  16 . These uprights  20  include and, in the illustrated example, are made up of door uprights each delimiting a border of a door arranged in one of the side walls of the body  1 . 
     The uprights  20  each comprise an upper end  21  and a lower end  22 . 
     The upper end  21  is connected to the roof module  16 . It forms a potential node of the body  1 . In the example of  FIG. 2 , torsional stresses are present in the upper end  21 , said stresses corresponding to a torque M 1  exerted around a transverse axis and in a first direction. 
     The lower end  22  is connected to the floor module  10 . It forms a potential node of the body  1 . In the example of  FIG. 2 , torsional stresses are present in the lower end  22 , said stresses corresponding to a torque M 2  exerted around a transverse axis and in a second direction opposite the first direction. 
     These stresses are typically produced by the weight of the body  1 , passengers, equipment and forces exerted at the longitudinal ends of the body by adjacent bodies (not shown). 
     The torque M 1  typically has a lower intensity than the torque M 2 . 
     Each wall module  12  further comprises at least one metal sheet  23  fixed between two uprights  20 , and at least one window  24  mounted between two uprights  20 , above a metal sheet  23 . 
     Each wall module  12  has an upper edge  30 , a lower edge  32  and longitudinal edges  34 . 
     The upper edge  30  is connected to the roof module  16 . The lower edge  32  is connected to the floor module  10 . The connections between the modules  10 ,  12 ,  16  are described in more detail below. 
     The longitudinal edges  34  are formed by the uprights  20 . 
     Each end module  14  comprises vertical beams  40  and horizontal beams  42 ,  44 , namely a lower beam  42  and an upper beam  44 . 
     The vertical beams  40  are connected to the wall modules  12 , the horizontal beam  42  is connected to the floor module  10  and the horizontal beam  44  is connected to the roof module  16 . 
     The roof module  16  for example comprises a vaulted structure and a sheet fixed on the vaulted structure, not shown. 
     The roof module  16  is connected to the upper edge  30  of each wall module  12  and the upper beam  44  of each end module  14 . 
     The connection between the modules  10 ,  12 ,  14 ,  16  is done by rivets. The rivets comprise lower rivets  50  and upper rivets  52 . 
     The lower rivets  50  connect each wall module  12  to the floor module  10 . In particular, the lower rivets  50  comprise groups of stiffening rivets  54  arranged in regions of the body  1  concentrating the torques M 2 . 
     These groups of stiffening rivets  54  are for example arranged at the lower end  22  of each upright  20 . 
     In reference to  FIG. 3 , each group of stiffening rivets  54  comprises at least three stiffening rivets  50 A,  50 B,  50 C and  50 D. In the illustrated example, there are four of these stiffening rivets  50 A,  50 B,  50 C and  50 D. 
     The stiffening rivets  50 A,  50 B,  50 C and  50 D each extend along the transverse direction of the body  1 . The heads of the stiffening rivets  50 A,  50 B,  50 C and  50 D are arranged in a vertical plane, perpendicular to the transverse direction of the body  1 . 
     Preferably, within each group  54 , the diameters of the stiffening rivets  50 A,  50 B,  50 C and  50 D are equal to one another. 
     The stiffening rivets  50 A,  50 B,  50 C and  50 D are arranged based on a distribution of mechanical stresses in the lower end  22 . 
     To that end, within each group  54 , the stiffening rivets  50 A,  50 B,  50 C and  50 D of said group  54  are arranged along a curve C formed in a plane perpendicular to a transverse direction of the body  1 . In other words, said stiffening rivets  50 A,  50 B,  50 C and  50 D are arranged such that it is possible to pass, through said stiffening rivets  50 A,  50 B,  50 C and  50 D, a common curve C contained in a plane perpendicular to a transverse direction of the body  1 . 
     A “curve” should be understood as a line with no straight portions. This curve C has no inflection point and is continuously differentiable. 
     “Continuously differentiable” means that, when the curve C is considered in the plane as a mathematical function, this function is at least of class C 1 , i.e., it is differentiable at all points, the derivative in turn being continuous. 
     The curve C extends from a first end  56  to an opposite second end  58 , said ends  56 ,  58  being defined respectively by a first stiffening rivet  50 A and a second stiffening rivet  50 D, said first and second stiffening rivets  50 A,  50 D longitudinally framing the other stiffening rivets  50 B,  50 C of the group  54 . The curve C has, at its first end  56 , a first tangent  60 , and at its second end  58 , a second tangent  62 , the angle α between said first and second tangents  60 ,  62  being less than or equal to 90°, in particular less than or equal to 70°, said angle α being measured in the clockwise direction from the first tangent  60  to the second tangent  62 . 
     The curve C is chosen such that, for each stiffening rivet  50 A,  50 B,  50 C,  50 D, shearing forces M 2 ′ exerted on the rivet  50 A,  50 B,  50 C,  50 D are oriented along a direction substantially tangent to the curve C. “Substantially tangent direction” means that the angle between said direction and the tangent to the curve C must be less than 10 degrees, preferably 5 degrees. 
     The distribution of the stresses is for example determined by measurement on a model of the body  1 . This model is preferably a digital model, the distribution of the stresses being determined by a digital simulation of said stresses for example by simulation using the finite elements method. 
     One skilled in the art will understand that other stresses, not shown, lower than the mechanical stresses due to the torque M 2 , may be present in the lower end  22 . In the example of  FIG. 3 , the torsional stresses make up the main stresses in the lower end  22 . 
     The mechanical torsional stresses are in particular present along the curve C. In the illustrated example, the curve C is in an arc of circle shape in the plane perpendicular to the transverse direction. 
     This arc of circle has a central point PC and a radius R. The radius R is for example between 100 mm and 200 mm, and preferably between 135 mm and 175 mm. 
     The upper rivets  52  connect each wall module  12  to the roof module  16 . 
     As shown in  FIG. 2 , the upper rivets  52  comprise groups of linear rivets  52 A,  52 B,  52 C. Each group of linear rivets  52 A,  52 B,  52 C comprises at least three upper rivets  52  aligned with one another within the group of linear rivets  52 A,  52 B,  52 C. 
     In other words, the upper rivets  52  are arranged along a line. This line for example extends along the longitudinal direction. 
     A method for manufacturing the body will now be described. 
     During a first step for designing the body  1 , a computer model of the body  1  is built, such as a model generated by CAD (Computer-Assisted Design), then static and dynamic loads are applied to said model, and the resultant stresses in the body  1  are calculated by a finite-element structure calculation. 
     In particular, the stresses resulting from the static and/or dynamic loads applied in the model of the body  1 , at an interface between the wall  12  and floor  10  modules, are measured. 
     After the design step, during the step for validating the body  1  through tests, the stresses are measured on a physical model of the body  1 , through equipment intended to measure stresses in said physical model. More specifically, the stresses resulting from static and/or dynamic loads applied in the physical model of the body  1  are measured, at the interface between the wall  12  and floor  10  modules in order to validate the distribution of the rivets  50 ,  54 . 
     Next, during a step for producing the body  1 , the body  1  is produced and assembled. The production step for example comprises pre-equipping each module  10 ,  12 ,  14 ,  16  and assembling the modules  10 ,  12 ,  14 ,  16  together. 
     During the pre-equipping of each module  10 ,  12 ,  14 ,  16 , the components of each module  10 ,  12 ,  14 ,  16  are assembled. In other words, each module  10 ,  12 ,  14 ,  16  is equipped before assembling the body  1 . 
     Each pre-equipped module is next preferably inspected at an inspection station. For example, the installation or correct operation of components of the pre-equipped module is inspected. 
     This pre-equipping is optional. 
     Then, during the assembly, the floor  10 , wall  12  and roof  16  modules are attached to one another by rivets. Optionally, the end module  14  is attached to the other modules  10 ,  12 ,  16  by rivets. 
     In particular, the stiffening rivets  50 A,  50 B,  50 C and  50 D are distributed within each group  54  along a curve formed in the plane perpendicular to the transverse direction of the body  1 . 
     The stiffening rivets  50 A,  50 B,  50 C and  50 D are arranged depending on the stresses measured in the body  1 . In particular, the rivets  50 A,  50 B,  50 C and  50 D are arranged in regions where mechanical torsional stresses are concentrated. 
     One can see that the railway vehicle body  1  makes it possible to reduce the number of rivets needed, while keeping sufficient stability. For example, while keeping the same stability of connections between the modules  10 ,  12 ,  14 ,  16 , the number of rivets needed is reduced from two thousand to two hundred. 
     Arranging the rivets  50 A,  50 B,  50 C and  50 D based on the mechanical stresses makes it possible to distribute the mechanical load evenly between said rivets  50 A,  50 B,  50 C and  50 D. In other words, each rivet  50 A,  50 B,  50 C and  50 D bears a uniform force. 
     Thus, the diameter of the rivets  50 A,  50 B,  50 C and  50 D can be optimized based on a uniform load, and not based on a maximum load.