Patent Publication Number: US-2019170252-A1

Title: Sealing gasket for railway vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims priority under 35 U.S.C. § 119(a) to, and incorporates herein by reference in its entirety for all purposes, French Application No. FR1761712, filed Dec. 6, 2017, entitled “SEALING GASKET FOR RAILWAY VEHICLE,” to Didier ROBERT et al., which is assigned to the current assignee hereof. 
     FIELD OF THE DISCLOSURE 
     The present description relates to a sealing gasket for a railway vehicle, with an engine or towed, in particular a train, subway tram car or carriage. 
     More specifically, the present invention relates to a gasket intended to produce sealing between a body of such a railway vehicle and an air conditioning unit topping said body. 
     BACKGROUND 
     A railway vehicle, intended to transport passengers or goods, typically may include a body delimited by a sheet metal enclosure, vertically topped by one or several air conditioning unit(s), fastened to the body by mechanical means, at a small distance from the sheet metal enclosure. 
     The intercalary space, arranged between the upper face of the sheet metal enclosure and the lower face of the air conditioning unit, houses air conditioning fluid circulation ducts, as well as many electrical and electronic circuits of the vehicle. 
     These ducts and circuits having to be protected from rain and bad weather to avoid electrical risks and damage of the components, the intercalary space may be sealed using sealing means positioned on its periphery. 
     In certain circumstances, a sealing gasket can be glued or rivited on the periphery of the air conditioning unit. The sealing gasket is intended to remain attached to the body under the effect of the weight of the air conditioning unit. It has, however, been noted that due to significant vibrations of the vehicle during use, the gasket tends to unstick from the body, allowing water and dust to enter. 
     More recently, it has been considered to fasten the gasket on the vehicle body instead of the air conditioning unit, provided, to that end, with a continuous rib protruding on its upper face. The sealing means in this case assume the form of a gasket, the upper part of which bears sealably against the air conditioning unit and the lower part of which, provided with an appropriate slot, may be intended to engage on the rib and grip it under the effect of a prestressed metal insert, overmolded to the inside of the gasket. This solution allows effective fastening, but has the drawback of being complicated and very costly to implement, due to the integration of the prestressed insert inside the gasket. 
     SUMMARY 
     The present invention aims to overcome the drawbacks of the prior solutions described above. 
     More specifically, the invention aims to provide a sealing gasket for a railway transport vehicle, making it possible to ensure good sealing of the intercalary space defined between the air conditioning unit(s) and the body of the vehicle, but that is inexpensive to manufacture. 
     The invention thus relates to a sealing gasket for producing sealing between a body of a railway vehicle and an air conditioning unit topping said body, said gasket may include a lower gasket part provided with a receiving slot suitable for receiving the rib of the body and an upper gasket part opposite the lower gasket part in a main direction, said upper part being suitable for sealably bearing against the air conditioning unit, the gasket being characterized in that the hardness of the lower gasket part is greater than that of the upper gasket part. 
     The gasket according to the invention may be a gasket having at least two different hardnesses (bi-hardness): Its lower part, oriented toward the body, may be rigid enough to allow solid fastening to the rib of the body, in particular during mounting or in case of maintenance, when the air conditioning unit is not yet in place or is temporarily removed. Its upper part may in turn be more flexible to guarantee good sealing with the air conditioning unit. 
     Such a bi-hardness gasket may in particular be obtained by coextrusion of two elastomers with different hardnesses, for example silicones. 
     The hardnesses of the lower and upper gasket parts are typically expressed in shore A hardnesses measured according to standard ISO 7619-1:2010. 
     According to one example, the upper gasket part has a shore A hardness may be between 25 and 65, preferably between 55 and 65. 
     According to one example, the lower gasket part has a shore A hardness may be between 65 and 95, preferably between 75 and 85. 
     According to one example, the difference in shore A hardness between the lower and upper gasket parts may be at least 10, preferably at least 15, preferably at least 20. 
     According to one example, the gasket may be equipped with retaining means protruding inside the receiving slot. These retaining means ensure effective gripping of the rib, preventing its disengagement. These retaining means for example may include at least one tongue or tooth, preferably a plurality of tongues or teeth, oriented toward the bottom of the receiving slot, thereby opposing a movement of the rib in the opposite direction. 
     According to one example, the upper gasket part may include at least one sealing lip at its end intended to come into contact with the air conditioning unit. The at least one sealing lip is gripped against the air conditioning unit, by its own elasticity. Preferably, the upper gasket part may include, at its end, two sealing lips oriented in different directions, and intended to come into contact with the air conditioning unit. 
     According to one example, the upper gasket part may include an elastic part suitable for deforming elastically in the main direction. Advantageously, this elastic part forms an intermediate part between the lower gasket part and the end (if applicable, comprising the sealing lip(s)) intended to create the sealed contact with the air conditioning unit. 
     The elastic part may be for example a cellular structure. Such a cellular structure preferably may include at least one cell forming a bellows, defining a closed cavity delimited by V-shaped or U-shaped side walls. 
     The cellular structure preferably may include at least two cells juxtaposed in the main direction. 
     The invention also relates to a railway vehicle, with an engine or towed, that may include a body and at least one air conditioning unit topping said body in a vertical direction, the body may include at least one continuous rib situated across from the air conditioning unit in the vertical direction, and the railway vehicle further may include at least one sealing gasket as previously defined between said body and said air conditioning unit with its main direction parallel to the vertical direction, the slot of the lower gasket part receiving the rib of the body, and the upper gasket part bearing sealably against the air conditioning unit. 
     Several example embodiments are described in this description. Unless otherwise specified, the features described in connection with any one example embodiment can be applied to another example embodiment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The details of the invention will be better understood upon reading the following description of one embodiment of the invention. In the context of the present invention, other embodiments are of course possible, the following description being provided solely as an illustration and not having to be considered limiting in any of its described aspects. 
         FIG. 1  is a schematic cross-section of a railway vehicle according to the invention; 
         FIG. 2  is a perspective top view of the body of  FIG. 1  (the elements topping the body being omitted); 
         FIG. 3  is an enlarged view of detail III of  FIG. 1 ; 
         FIG. 4  is a detail view of the gasket of  FIG. 1 , in the non-compressed state; 
         FIG. 5  shows the gasket of  FIG. 4  in its maximal compression state. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a cross-section of a train carriage  10  according to the present invention. 
     The carriage  10  may include: 
     a body  20  intended to house travelers or goods, which may include a main enclosure  24  generally made from sheet metal, mounted on a plurality of wheels  22  suitable for cooperating with the rails of a railroad track (not shown), and 
     at least one air conditioning unit  30  positioned above the body  20  in the vertical direction Z of the carriage, and fastened to the body  20  by mechanical means known in themselves (not shown). 
     The vertical direction Z of the carriage, generally orthogonal to the upper face  24   a  of the enclosure  24  or to the contact plane P of the wheels  22 , generally corresponds, in practice, to the direction of gravity. 
     A horizontal direction is orthogonal to this vertical direction Z. 
     The air conditioning unit  30  typically has a metal case with a substantially parallelepiped shape with horizontal dimensions smaller than those of the body  20 , typically 2 m*4 to 5 m. 
     An intercalary space  40  may be formed vertically between the air conditioning unit  30  and the body  20 . 
     As previously explained, this intercalary space  40  houses air conditioning fluid circulation ducts  42  and/or electrical circuits  44  and/or electronic circuits  46 , which must be protected from outside attacks (air, water, dust). 
     The intercalary space  40  may therefore be sealed by sealing means described below. 
     As illustrated in  FIG. 1 , the main enclosure  24  of the body  20  bears, on its upper face (roof)  24   a , at least one continuous rib  26  closed on itself, illustrated in more detail in  FIG. 2 . 
     The rib  26 , which limits the horizontal expanse of the intercalary space  40 , faces, over its entire length, the lower face  30   b  of the air conditioning unit  30 , in the vertical direction Z. 
     The rib  26  extends vertically (and orthogonally to the upper face  24   a  of the enclosure  24 ). It assumes the form of a ribbon, in particular made from steel, for example welded to the upper face  24   a  of the enclosure  24 , with a constant thickness  11  that may be between 2 and 6 mm, preferably between 2 and 4 mm, and with a height h 1  (measured vertically) that may typically be between 10 and 30 mm. 
     The rib  26  typically forms a rectangular frame, with corners that are preferably slightly rounded, horizontal dimensions that are generally substantially equal to those of the air conditioning unit. Preferably, the rib may be horizontally offset by a distance d, for example by several centimeters, relative to the lateral edges of the air conditioning unit. 
     The means ensuring the sealing between the body  20  and the air conditioning unit  30  may include a continuous gasket  50  closed on itself, intended to cooperate with this rib  26 . 
     The sealing gasket  50 , illustrated in more detail in  FIG. 3 , may be broken down into a lower gasket part  60  intended for fastening thereof on the body  20 , and an upper gasket part  70  intended to produce the sealing with the air conditioning unit  30 , said upper part  70  being opposite the lower gasket part  60  in a direction called main gasket direction Z 1 . 
     In practice, after assembly, this main gasket direction Z 1  is parallel to the vertical direction Z of the carriage  10 , and therefore to the direction of gravity. 
     Defined, at any point of the gasket  50 , is a longitudinal direction Y 1  extending in the direction of the length of the gasket, orthogonally to the main direction Z 1 . Unless otherwise indicated, the lengths mentioned below are measured in this longitudinal direction. 
     Lastly, a lateral direction X 1  is defined, orthogonal to the aforementioned main Z 1  and longitudinal Y 1  directions. Unless otherwise indicated, the widths defined below are measured in this lateral direction. 
     According to the invention, the lower  60  and upper  70  gasket parts may have different hardnesses. The upper part  70  may be more flexible, to ensure good sealing. The lower part  60  may be more rigid, to guarantee solid fastening on the body, withstanding vibrations and impacts, and guaranteed even in case of removal from the air conditioning unit  30  in the context of maintenance operations. 
     The gasket  50  may be for example obtained by co-extruding two different elastomeric materials, one for each lower or upper part of the gasket. 
     The material making up the upper gasket part  70  advantageously may have a shore A hardness of between 25 and 65, preferably between 55 and 65, still more preferably 60, and the material making up the lower gasket part  60 , may have a shore A hardness of between 65 and 95, preferably of between 75 and 85, still more preferably 80. It is recalled that the shore A hardness is measured according to standard ISO 7619-1:2010. 
     The difference in shore A hardness between the lower  60  and upper  70  gasket parts may preferably be at least 10, preferably at least 15, preferably at least 20. 
     As illustrated in  FIG. 3 , the lower gasket part  60  for example may have a minimum width  12  of between 10 and 20 mm, and a height h 2  may typically be between 12 and 20 mm. 
     It globally has an inverted U-shaped profile comprising two side branches  66   a ,  66   b  and a base  66   c , delimiting a slot  62  emerging on its lower face  60   b , the slot  62  being delimited by two facing side walls  62   a ,  62   b , and a bottom  62   c  connecting said side walls. 
     The width  13  of the slot  62  at its emerging end may be for example between 2 and 6 mm. 
     It should be noted that the side walls  62   a ,  62   b  can be parallel like in the illustrated example, or may not be. According to another example, the slot may in particular flare toward the bottom  62   c.    
     The depth h 3  of the slot  62 , measured in the main direction Z 1  between the end of the lower gasket part  60  where it emerges all the way to the bottom  62   c , may be typically between 10 and 20 mm. 
     The lower gasket part  60  may be engaged, by this slot  62 , called receiving slot, on the rib  26  of the body  20 . In practice, after mounting, the distal end of the rib  26  abuts against the bottom  62   c  of the slot  62 , as illustrated in  FIG. 3 . 
     At minimum, the rib  62  may be retained by the adherence with the walls of the slot  62 . However, preferably, the respective widths of the rib  26  and the slot  62  are chosen to produce a pinching effect of the rib  26 . In practice, the width  13  of the slot  62  may be then chosen to be smaller than the width of the rib  26 , at least at its emerging end. As previously claimed, the slot  62  may then have either a constant width over its entire expanse in the main direction Z 1 , or a variable width, generally greater than or equal to the minimum value measured at the emerging end. Consequently, the two branches  66   a ,  66   b  are separated during mounting on the rib  26 , and due to the elasticity of the material, form said clamp, which applies a lateral pinching force on the rib  26 . 
     Due to its hardness, the lower gasket part  60  makes it possible to grip, firmly retain the rib  26 , and avoid separation of the gasket  50  in case of strong biases, or when the air conditioning unit is not in place, for example during mounting or during maintenance operations. Such a connection must typically withstand a pulling out force of at least 30 N. 
     According to one advantageous arrangement of the invention illustrated in  FIG. 4 , additional retaining means, increasing the pulling out strength of the gasket  50 , protrude inside the receiving slot  62 . 
     These retaining means can assume the form of one or several tongue(s)  64  that are continuous over the entire length of the gasket  50 , formed on one or both side face(s)  62   a ,  62   b  of the slot  62 , and here oriented toward the bottom  62   c . When a tensile bias is exerted, the gasket  50  and the rib  26  are prevented from disengaging due to the tongues  64 , which, sufficiently rigid, do not deform and retain the rib  26 . 
     In the illustrated example, the tongues  64  are situated across from one another in the lateral direction X 1 . As an alternative, they can also be offset relative to one another in the main direction Z 1 . 
     As an alternative, the retaining means may assume the form of localized teeth, preferably oriented toward the bottom of the slot. 
     The retaining means can also be formed by a combination of tongues and teeth, or any other means suitable for preventing the disengagement of the rib  26  and the gasket  50 , in the main direction Z 1 . 
     The upper gasket part  70  may be intended to react the forces related to the impacts and vibrations of the carriage  10 , while ensuring sealed bearing on the air conditioning unit  30 , continuous over the entire length of the gasket  50 . 
     The upper gasket part  70  may be suitable for deforming in the vertical direction Z in case of impacts or vibrations of the carriage  10 . It forms a spring so to speak, compressed continuously, recalled against the air conditioning unit  30  by its own elasticity. 
     According to one example embodiment, the upper gasket part  70  may include, near the lower part  60 , a cellular elastic part  80 . 
     In the example illustrated in  FIG. 4 , the cellular structure  80  has an accordion shape. It may be formed by two cells  82   a ,  82   b , each defining a closed cavity  84   a ,  84   b , laterally delimited by deformable walls  86   a ,  88   a ;  86   b ,  88   b  with a V-shaped or U-shaped section. Each cell forms a bellows, suitable for compressing or expanding in the main direction Z 1 , and thus absorbing the vibrations of the carriage during operation. Such a cellular structure has an optimal compressibility in the main direction Z 1  with restricted widening in the lateral direction X 1 . 
       FIG. 5  illustrates the gasket  50  of  FIG. 4  in its maximal compression state. The gasket may be only very slightly widened, and therefore only very moderately encroaches on the inner volume of the intercalary space  40 . 
     The upper gasket part  70  further may include, topping the elastic part  80 , an upper end part  90  here formed by two sealing lips  92 ,  94  oriented in opposite directions, and intended to form a sealed contact with the lower face  30   b  of the air conditioning unit  30 . 
     As an alternative, the upper gasket part may include a number of lips different from two, for example a single lip or plurality of lips oriented in the same direction or in opposite directions, or any other elements suitable for producing the sealing with the air conditioning unit. 
     Many different aspects and embodiments are possible. Some of those aspects and embodiments are described herein. After reading this specification, skilled artisans will appreciate that those aspects and embodiments are only illustrative and do not limit the scope of the present invention. Embodiments may be in accordance with any one or more of the items as listed below. 
     Embodiment 1 
     A sealing gasket for producing sealing between a body of a railway vehicle ( 10 ) and an air conditioning unit ( 30 ) topping said body, said gasket ( 50 ) comprising a lower gasket part ( 60 ) provided with a receiving slot ( 62 ) suitable for receiving the rib of the body and an upper gasket part ( 70 ) opposite the lower gasket part in a main direction (Y 1 ), and suitable for sealably bearing against the air conditioning unit ( 30 ), the gasket being characterized in that the hardness of the lower gasket part ( 60 ) is greater than that of the upper gasket part ( 70 ). 
     Embodiment 2 
     The gasket ( 50 ) according to embodiment 1, wherein the upper gasket part ( 70 ) has a shore A hardness comprised between 25 and 65. 
     Embodiment 3 
     The gasket ( 50 ) according to embodiment 1, wherein the lower gasket part ( 60 ) has a shore A hardness comprised between 65 and 95. 
     Embodiment 4 
     The gasket ( 50 ) according to any one of embodiments 1 to 3, wherein a difference in shore A hardness between the lower ( 60 ) and upper ( 70 ) gasket parts is at least 10. 
     Embodiment 5 
     The gasket ( 50 ) according to any one of embodiments 1 to 3, wherein the lower ( 60 ) gasket part is a silicone. 
     Embodiment 6 
     The gasket ( 50 ) according to any one of embodiments 1 to 3, wherein the upper ( 70 ) gasket part is a silicone. 
     Embodiment 7 
     The gasket ( 50 ) according to any one of embodiments 1 to 3, wherein the lower ( 60 ) and the upper ( 70 ) gasket parts are silicones. 
     Embodiment 8 
     The gasket ( 50 ) according to any one of embodiments 1 to 3, wherein the gasket ( 50 ) is equipped with retaining means ( 64 ) protruding inside the receiving slot ( 62 ). 
     Embodiment 9 
     The gasket ( 50 ) according to embodiment 8, wherein the retaining means ( 64 ) comprise at least one tongue or tooth oriented toward the bottom of the receiving slot ( 62 ). 
     Embodiment 10 
     The gasket ( 50 ) according to any one of embodiments 1 to 3, wherein the upper gasket part ( 70 ) comprises at least one sealing lip ( 92 ,  94 ) at its end intended to come into contact with the air conditioning unit ( 30 ). 
     Embodiment 11 
     The gasket ( 50 ) according to any one of embodiments 1 to 3, wherein the upper gasket part ( 70 ) comprises a cellular structure ( 80 ) suitable for deforming elastically in the main direction (Y 1 ). 
     Embodiment 12 
     The gasket ( 50 ) according to embodiment 11, wherein the elastic cellular structure ( 80 ) comprises at least one cell ( 82   a ,  82   b ) forming a bellows, defining a closed cavity ( 84   a ,  84   b ) delimited by V-shaped or U-shaped side walls ( 86   a ,  88   a ;  86   b ,  88   b ). 
     Embodiment 13 
     The gasket ( 50 ) according to embodiment 11, wherein the cellular structure ( 80 ) comprises at least two cells ( 82   a ,  82   b ) juxtaposed in the main direction (Y 1 ). 
     Embodiment 14 
     A railway vehicle ( 10 ), with an engine or towed, comprising a body ( 20 ) and at least one air conditioning unit ( 30 ) topping said body in a vertical direction (Z), the body ( 20 ) comprising at least one continuous rib ( 26 ) situated across from the air conditioning unit ( 30 ) in the vertical direction (Z), and the railway vehicle further comprising at least one sealing gasket according to any one of embodiments 1 to 13 between said body ( 20 ) and said air conditioning unit ( 30 ) with its main direction (Z 1 ) parallel to the vertical direction (Z), the slot of the lower gasket part ( 60 ) receiving the rib ( 26 ) of the body ( 20 ), and the upper gasket part ( 70 ) bearing sealably against the air conditioning unit ( 30 ).