Patent Publication Number: US-10766504-B2

Title: Floor structure provided with a fire protection system for railway vehicles

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This application is a U.S. National Phase Application under 35 U.S.C. § 371 of International Patent Application No. PCT/IB2016/054530, filed Jul. 28, 2016, which claims the priority of Italian Application No. 102015000039111, filed Jul. 28, 2015, which is incorporated by reference as if expressly set forth in its entirety herein. 
     TECHNICAL FIELD 
     The present invention relates to a floor structure provided with a fire protection system for railway vehicles. 
     BACKGROUND ART 
     As is known, railway and subway carriages each have a body or shell provided with an underframe which defines the base for the inner floor of the carriage itself. Normally, the underframe must meet technical standards and specifications relating to fire resistance, particularly resistance to fire (REI) of 30 minutes. To meet these requirements, especially when the underframe is made of aluminium, its lower surface is coated with intumescent paint, applied by using spraying technology. 
     This solution, though widely used, must be performed in specific areas equipped for painting operations and requires high line crossing times in the production cycle. 
     US2014238262 describes a solution according to the preamble of claim  1 , where the fire protection system is defined by a panel with insulating material fixed to the underframe. 
     DISCLOSURE OF INVENTION 
     The object of the present invention is to provide a floor structure provided with a fire protection system for railway vehicles, which makes it possible in a simple and economical manner to solve the problems described above, has the necessary fire resistance characteristics and can be assembled in a relatively simple manner. 
     According to the present invention a floor structure is provided with a fire protection system for railway vehicles, as defined in claim  1 . 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described with reference to the accompanying drawings, which illustrate a non-limiting embodiment thereof, in which: 
         FIG. 1  shows, in perspective from below and partially, a preferred embodiment of the floor structure provided with a fire protection system for railway vehicles according to the present invention; 
         FIG. 2  shows in a simplified manner and on an enlarged scale, a cross-section of the floor structure according to the vertical cross-section plane indicated by the line II-II in  FIG. 1 ; 
         FIG. 3  is a side view of a component of  FIG. 2 , on a further enlarged scale and with parts removed for clarity; 
         FIGS. 4 and 5  show two details of the floor structure of  FIG. 2 , again in cross-section; and 
         FIG. 6  illustrates, in perspective and with parts removed for clarity, a detail of  FIGS. 2 and 5 . 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     In  FIG. 1 , reference numeral  1  denotes a floor structure of a railway vehicle, i.e. a train or a subway. The structure  1  comprises an underframe or platform  2 , which is part of a body or shell of a carriage of the vehicle and has a top surface  3  supporting or defining an inner floor (not illustrated) of such carriage. 
     The underframe  2  is elongated along a straight longitudinal axis  4  which corresponds to the longitudinal axis of advancement of the railway vehicle. The underframe  2  has a lower surface  5  opposite the surface  3  and comprises a plurality of attachment tracks or rails  10  ( FIG. 2 ), commonly referred to as “rails”, and arranged in correspondence with an intermediate area of the surface  5 . In particular, such intermediate area is located centrally along the axis  4  and occupies the entire width of the underframe  2  (i.e. extends from one lateral end to the other). 
     With reference to the cross-section in  FIG. 2 , the attachment rails  10  are parallel to the axis  4  and are normally used to attach one or more supports  12  ( FIG. 5 ) to which the so-called underframe equipment (not shown)—for example the container for the batteries, the inverter, the rheostat, etc.—is then coupled. 
     The attachment rails  10  are defined by downward protrusions so as to horizontally define therebetween a plurality of compartments  13 . 
     In particular, the underframe  2  is composed of extruded elements  14  made of aluminium alloy, so that the attachment rails  10  constitute part of the extruded elements  14 . 
     In particular, as may be seen in  FIG. 4 , each attachment rail  10  comprises two vertical appendages  16 , substantially L-shaped and defining therebetween a longitudinal channel  17 , substantially T-shaped. The channel  17  is thus open towards the bottom at a longitudinal slit  18 , defined by the ends of the appendages  16 . The channel  17  of each attachment rail  10  houses a plurality of attachment elements  19 , each of which has at least one threaded hole  20 , vertically aligned with the slit  18 , and longitudinally sliding in the channel  17  to adjust the position of the hole  20  and of a sufficiently large size not to come out through the slit  18 . 
     Returning to  FIGS. 1 and 2 , the floor structure  1  comprises a fire protection system  21 , which covers at least a part of the surface  5  and comprises a plurality of panels  22  arranged in the compartments  13 . 
     Each panel  22  has a width such as to nearly fill the compartment  13 , i.e. the transverse space between two adjacent attachment rails  10 . 
     The thickness of the panels  22  is less than the height of the appendages  16 , so as not to protrude beyond the attachment rails  10 , in order not to interfere with any equipment or components (brackets, ducts etc.), not illustrated, to be subsequently fitted to the carriage in the underbody area. 
     With reference to  FIG. 3 , each panel  22  has a surface  23 , which is facing upwards, is flat and is coupled to the surface  5  with the interposition of sealing strips  24 , preferably made of a silicone, closed cell, foam-based material. 
     According to one aspect of the present invention, each panel  22  comprises a tank or container  25 , in stainless steel sheet, with relatively low thickness, for example less than 0.5 mm (in particular equal to 0.3 mm). The container  25 , in particular, has a substantially parallelepiped outer shape, and has: a surface  26  facing downwards; two side faces  27 , which are opposite each other and are facing towards respective attachment rails  10 ; and two end faces  28 , facing towards the faces  28  of adjacent panels  22 . 
     The length of the container  25  is sized so as to fill each compartment  13  by means of a series of aligned panels  22 , all having the same length. In other words, this way the length of the panels  22  is standardised to optimise the management of warehouse stocks (to reduce the raw material codes to be managed). In particular, the standard length of the container  25  is between 1150 and 1200 mm, so as to compromise between the need to minimise the number of aligned panels to be installed in each compartment  13  and the need to adapt to different lengths of compartment  13 . 
     Advantageously, the surface  26  has an embossed appearance or finish ( FIG. 6 ) to improve its rigidity. 
     Each container  25  is closed on all six sides, so that even the surface  23  is defined by a sheet of the container  25 . 
     In particular, for at least some of the panels  22 , the container  25  comprises two metal half-shells which are attached to each other so as to completely enclose the insulating material therebetween. In particular, the two half-shells have a C-shaped cross-section and/or the container  25  is composed solely of the two half-shells. 
     Between the faces  28  of adjacent panels  22  at least one strip or gasket  29  is interposed consisting of intumescent material, i.e. material which expands above an activation temperature, for example a temperature of 200° C. 
     Each panel  22  further comprises a core or nucleus  30 , commonly called “core”, arranged in the housing defined by the container  25 , in such a way as to completely fill such housing, and consisting of high capacity thermal and fire insulation material (in particular, low thermal conductivity at high temperatures). Such material can be found commercially and chosen according to the fire protection and thermal insulation specifications to be met. Preferably, a material indicated by the trade name FIREMASTER® Marine Plus is used. 
     Some of the panels  22  comprise a tab  31 , which is defined by sheet in the same material as the container  25 , protrudes horizontally and longitudinally with respect to one of the faces  28  and is substantially flush with the surface  26  so as to overlap an adjacent panel  22  to cover any empty space between the faces  28  of two panels  22  arranged consecutively with each other in the same compartment  13 . In particular, the tab  31  constitutes part of a bracket which is L-shaped and defines the aforesaid face  28 . Thanks to the tab  31 , the continuity of the fire protection system is guaranteed. 
     With reference to  FIG. 4 , the fire protection system  21  further comprises a plurality of section bars  32 , which are made of stainless steel, and are attached to the attachment rails  10  by metal mechanical elements  33 , for example screws. The section bars  32  are shaped so as to retain the panels  22  in fixed positions in the compartments and, at the same time, to cover the bottom of the attachment rails  10 , in order to ensure fire protection of the rails themselves. It follows that the section bars  32  also cover any gaps between the attachment rails  10  and the side faces  27 . 
     The sealing strips  24  are carried, in fixed positions, by the surface  23 . During assembly, the sealing strips  24  are kept in contact with the underframe  2  until the section bars  32  are attached to the attachment rails  10  by means of the elements  33 . 
     The cross-section of the section bars  32  is an open section having a shape of an upside-down omega, and comprises an intermediate wall  36 , which is substantially horizontal and is placed under the corresponding attachment rail  10 . 
     The upper surface (i.e., the inner surface) of the wall  36  is completely covered by a strip of fire barrier material  37 , in particular in a muscovite or phlogopite-based material, which therefore remains interposed between the wall  36  and the attachment rail  10 . 
     The wall  36  and the strip  37  are provided with at least one hole  38  which, in the vertical direction, is a through hole and is aligned with a corresponding hole  20 . At the same time, the elements  33  are defined by respective screws, which engage the holes  38  and are screwed into the holes  20  to lock the section bar  32  to the attachment rail  10 . 
     The cross-section of the section bars  32  ends laterally with two flanges or fins  39 , which are opposite to each other, are substantially horizontal and are supported on the lateral ends of the surface  26 , preferably by means of the interposition of respective sealing strips  40 , similar to the sealing strips  24 . 
     Again considering the cross-section of the section bar  32 , the two fins  39  are joined to the lateral longitudinal edges of the wall  36  by means of respective walls  41 , which are arranged on opposite sides of the attachment rail  10  and are substantially vertical. 
     The inner surfaces of the walls  41  are covered by respective strips or gaskets  42  of intumescent material, similar to that of the strips  29 . The strips  42  are facing, and preferably spaced, with respect to the sides of the attachment rail  10 , to enable the expansion of the intumescent material in the event of exposure to fire. 
     With reference to  FIG. 6 , at the area where the support  12  is to be fixed, the attachment rail  10  is devoid of the section bar  32 . In other words, the attachment rail  10  carries two section bars  32  which are spaced longitudinally from each other so as to leave an interruption or opening  44  therebetween at such area. 
     As seen in  FIG. 5 , the opening  44  is closed by an additional closure section bar  45 , the cross-section of which has also the shape of an upside-down omega, with an intermediate wall  46 , with two opposite end fins  47  and with two walls  48  which join the fins  47  to the lateral longitudinal edges of the wall  46 . 
     The longitudinal ends of the section bar  45  are superposed and coupled to the longitudinal ends of the two section bars  32  visible in  FIG. 6 , so as to close any empty space by means of sealing gaskets, similar to the strips  24 . 
     In this area, a spacer, defined by a U-bolt  51  in U-shaped stainless steel, is interposed between the attachment rail  10  and the section bar  45 . The U-bolt  51  and the wall  46  are provided with at least one hole  53  which, in the vertical direction, passes through and is aligned with a corresponding hole  20 . The hole  53  is engaged by a screw  54  which is screwed into such hole  20 , to keep the support  12  stationary against the wall  46  and, thus, block both the section bar  45  and the support  12  to the attachment rail  10 . 
     Between the upper surface of the wall  46  and the U-bolt  51  a strip or gasket  49  is provided, made of fire barrier material, for example of fibres embedded in epoxy resin. Between the vertical walls  48  of the section bar  45  and the U-bolt  51  gaskets or strips  50  made of intumescent material similar to that of the strips  42 ,  29  are interposed. 
     The upper surfaces of the fins  47  are coated with sealing strips  52  similar to the strips  40 , but generally of greater thickness, so as to cover the greater distance from the surface  26  of the panels  22 . 
     Along the side edges of the underframe  2  (not shown), suitable expedients (not illustrated) are used to ensure the sealing and the resistance to fire of any spaces between the panels  22  and said edges. 
     During assembly, the underframe  2  is coated with the fire protection system  21 , arranging the panels  22  in the compartments  13  and then attaching the section bars  32 ,  45 . The assembly of the fire protection system  21  can be performed while keeping the underframe  2  in the tilted, upside-down position before assembling the vehicle body, or after assembling said body working from below the surface  5 . 
     It is evident from the above how the operations for coating the underframe  2  with the fire protection system  21  do not require painting along assembly lines and can be carried out quickly and easily without any special specific equipment. 
     In particular, the realization of the panels  22  and any treatments of the panels  22  and/or of the section bars  32 ,  45  (including any painting operations) can be performed outside the assembly lines, so that the latter tend to be simpler compared to the prior solutions. Furthermore, it is possible to standardise the size of the panels  22  to make this solution as modular as possible. 
     Moreover, no changes are made to the conventional underframes, which correspond exactly (in terms of configuration, characteristics and dimensional proportions) to the underframe  2  shown by way of example. In particular, to stably attach the panels  22  the attachment rails  10  are used, which are already provided in the known underframes. 
     At the same time, the fire protection system makes it possible to obtain excellent performance as regards fire resistance without excessively increasing the weight of the vehicle. 
     Furthermore, the number of components of the fire protection system  21  is relatively low, both because the dimensions of the panels  22  are standardised, and because the section bars  32  perform a dual function, i.e. allow the attachment of the panels  22  and cover the attachment rails  10 . 
     From the above, lastly it appears evident that modifications and variations may be made to the floor structure  1  described with reference to the appended drawings while remaining within the sphere of protection of the present invention as defined in the appended claims. 
     In particular, the entire length of a compartment  13  may be occupied by a single panel, instead of providing a plurality of panels  22  placed alongside each other; and/or the attachment rails  10  may have a cross-section with a shape different to that shown by way of example. 
     Even the shape of the cross-sections of the section bars  32  and  45  may be different from those shown, depending on the vertical thickness of the panels  22  and/or depending on the height and the shape of the attachment rails  10 .