Railway composite wagon body and method for its manufacture

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention is included in the field of terrestrial vehicle structures, in particular railway structures, and also in that of the composite materials structures.

[0002] The field of application of the present invention is that of railway vehicles where weight savings can be an advantage, whether transporting cargo or passengers.BACKGROUND OF THE INVENTION

[0003] Railway cars are usually manufactured in metal. However, in last years the introduction of high-speed trains and the need to reduce the energy consumption for environmental reasons, has led to look for mass savings in new trains construction. The change from a metal structure to a structure built in composite materials represents a good opportunity for weight savings, reason why the construction of railway cars in composite materials has been a field of interest in last years.

[0004] The roughly tubular shape of a train car offers two main alternatives when designing a railway car structure to be manufactured in composites: the manufacturing of roughly flat panels that will constitute the floor, ceiling and lateral walls of the train car, and that are later assembled together, or the manufacturing of the whole car body as a square section tube, by filament winding or other similar techniques.

[0005] EP0554539 describes a composite coach body manufactured integrally by means of filament winding or similar technologies, where layers of composite material are wound on a winding mandrel. This patent describes the utilization of corner profiles included in the structure to act as longitudinal beams to carry longitudinal loads. The structure described also includes a stiffening network made up of stiffeners that run both in longitudinal direction and transversally, to stiffen the final structure.

[0006] EP3580108 describes a carriage body for a rail vehicle made up of several panels of composite materials assembled together. The car body is composed of a roof, two side walls and a floor panel, the side walls including longitudinal beams that, in addition to act as load carrying members, also act as connecting elements between the lateral panels and the floor and roof panels.

[0007] Manufacturing a railway car in a single part by winding fibers around a mandrel has the advantage of eliminating the need to make joints between different panels, which could save manufacturing time and cost. However, it is difficult to include reinforcing elements to stiffen the final tubular structure in the transversal direction, which usually requires the inclusion of those stiffeners as separate elements that have to be later assembled to the wound tubular structure. It is difficult also, with this configuration, to assign different stiffness depending on the area, which usually requires the ulterior addition of reinforcements to the most demanding areas. Moreover, this technology requires large facilities and specific machinery to wound the whole railway car on a rotating mandrel.

[0008] Manufacturing the railway car by assembling panels, on the other hand, eliminates the need for specific winding machinery or large facilities. Also, the panels may be constructed including stiffeners that will stiffen the final car structure in the transversal direction. But this type of construction adds the need of assembling the different panels together while maintaining the required stiffness in the joints. EP3580108 solves this by making coincident the joints with the longitudinal beams, and by using additional elements (fittings, etc) to join those beams to the adjacent panel without losing rigidity in the joint. However, this adds new parts (fitting elements), with their added weight and cost, and complicates the assembly process, further increasing the associated manufacturing costs.

[0009] The present invention describes a new concept for manufacturing railway cars in composite materials by manufacturing separated panels that include the required stiffening elements and that are easily assembled together while maintaining a good transversal rigidity in the final structure of the car.BRIEF DESCRIPTION OF DRAWINGS

[0010] Present specification is complemented with a set of drawings, illustrative of the preferred example and never limiting the invention. Fig 1 shows a global view of the railway car structure of the invention, typically composed of four panels joined together. Fig 2 is a view of a typical lateral panel with integrated vertical stiffeners. Fig 3 is a view of a typical floor panel with integrated transversal longerons, longitudinal beams and two longitudinal flaps for joining the lateral panels. Fig 4 is a exploded view of the floor panel shown on Fig 3 to see its component elements with more clarity. Fig 5 is a view of a typical roof panel with integrated transversal stiffeners, longitudinal beams and two flaps for joining the lateral panels. Fig 6 is a sketch view showing the joint between floor and lateral panels, and including additional reinforcing layers on the outer surface. Fig 7 is a sketch view showing the joint between roof and lateral panels, and including additional reinforcing layers on the outer surface. Fig 8 shows two mating parts to give continuity to the transversal stiffeners of the different panels in the final structure. Fig 9 shows the finished car body structure after installing the mating parts to give continuity to the transversal stiffeners on the panels and form closed frames. Fig 10 is a sketch of the section of a roof or lateral panel with an integrated stiffener with "omega" section manufactured in composite including a lightweight core. Fig 11 is a sketch of the section of a roof or lateral panel with an integrated stiffener with "omega" section manufactured in composite without any core. DESCRIPTION OF THE INVENTION

[0011] The present invention introduces a new composite railway car structure composed of several composite panels (usually four) assembled together, and including transversal stiffeners and longitudinal beams integrated in the panels.

[0012] The division of the car body into different panels may be done in many different ways, but from the point of view of manufacturability and costs, it is usually better to make the partition trying to obtain panels that are as flat as possible. This usually leads to a partition into floor, roof and lateral panels, although more partitions could be done if considered convenient for any reason, such as the need to manufacture smaller panels. In the longitudinal direction, the panels can be a single part from end to end of the car (not taking into account the closing structures at each end of the car), or may be also partitioned into several panels.

[0013] In a typical configuration (Fig 1), presented as a typical example and not limiting the invention, the car body (1) comprises a floor panel (10), a roof panel (20), and two lateral panels (30).

[0014] The lateral panels (30, Fig 2) are composite elements manufactured in fiber reinforced plastic with integrated stiffening elements. The lateral panels could be of monolithic or sandwich configuration, or a combination of both, depending on the zone considered.

[0015] The lateral panels include integrated vertical stiffeners (320) that could usually have an "omega" or "hat" section and that will form transversal frames for the car body as it will be later explained. If the lateral panels include windows openings, as it is usual in passenger cars, these stiffeners will typically run vertically between adjacent windows (Fig 2).

[0016] In the areas below and above the windows it is usual to have to stiffen the lateral panels to give them the required rigidity. This could be done by including integral stiffeners on those areas, but it is usually preferred to make those areas in a sandwich configuration, with an internal core that, in addition to giving rigidity, also provides some thermal and acoustic insulation. (Fig 2)

[0017] The floor panel is where most of the loads apply: weight loads coming from the cargo and the car structure itself, and reaction loads from wheels and bogies are transmitted through the floor of the car. For this reason, the floor of the car usually needs to be more rigid than the rest of the car structure.

[0018] The floor panel (10) of the invention is a composite sandwich panel with substantially flat upper and lower faces that comprises two longitudinal beams (110) embedded in the areas that will form the lower corners of the car structure (Fig 3, Fig 4). The floor panel also includes transversal longerons (120) embedded in the core area of the sandwich and with their location coordinated with the stiffeners (320) of the lateral panels. The longitudinal beams and transversal longerons are first manufactured as separated parts and later embedded in the sandwich structure of the floor, in the core area between the lower and upper faces, during the manufacturing of the floor panel. The intermediate zones between the upper and lower faces and between the beams and longerons is filled with a lightweight core material, usually a foam, although other typical cores used for sandwich panels construction, such as honeycomb, may be used. Additional reinforcements may be included in the core area depending on stress and stiffness requirements, such as additional longitudinal or transversal longerons. The beams and longerons may be manufactured in fiber reinforced plastic (preferred), or other materials (metals, etc.).

[0019] The floor panel (10) also includes two lateral flaps (130) coming out of the corner beams areas, disposed to receive the lateral panels and to join to them in a simple lap joint (Fig 3, Fig 4, Fig 6).

[0020] The roof panel (20, Fig 5) is also a composite element manufactured in fiber reinforced plastic that includes the two upper longitudinal corner beams (210) and transversal stiffeners (220) that could have an "omega" or "hat" section and whose location will match that of the vertical stiffeners (320) of the lateral panels.

[0021] The longitudinal beams (210) are first manufactured as separated parts and later integrated in the roof panel during its lamination process.

[0022] The transversal stiffeners (220) may be separated parts that are later attached (bonded or fastened) to the roof panel once the panel is already manufactured, but it is usually preferred from a point of view of cost and weight to integrate them in the panel during the lamination process, thus manufacturing an integrated single part that includes both the longitudinal beams and the transversal stiffeners.

[0023] Between the transversal stiffeners of the roof panel it is usually preferred to include a sandwich section where the core of the sandwich gives rigidity and also some thermal and acoustic insulation to the roof panel.

[0024] The roof panel (20) also includes two lateral flaps (230) coming out of the corner beams areas, disposed to receive the lateral panels and to join to them in a simple lap joint (Fig 5, Fig 7).

[0025] The car body is assembled by joining the lateral panels to the floor and roof panels. This is done by making a lap joint between the flaps (130, 230) of the floor and roof panels, and the lateral panels (30) (Fig 6, Fig 7). The joint is usually preferred to be done using adhesives, although fasteners (rivets, bolts...) may also be used, or a combination of both. The thickness and width of the flaps (130, 230) are calculated for the joint to be able to withstand the required loads in the final structure of the car body.

[0026] Optionally, the lap joints between the lateral panels and the floor and roof panels may be locally reinforced with the application of some layers of composite material to act as reinforcements (400) covering the joint area (Fig 6, Fig 7). These reinforcements may be applied on the outer surface of the joint or on its inner surface, or on both sides, but usually it is easier to apply them on the outer surface because it is a more continuous surface.

[0027] To better stabilize the final car body, once the different panels forming the structure have been joined together it is recommended to give continuity to the transversal stiffeners integrated in the different panels. To do so, first, the transversal stiffeners of each panel must be coordinated so that they are aligned once the car body assembly has been performed (Fig 1). In the case of the floor panel, where there are no protruding stiffeners since it is a flat sandwich structure, the transversal longerons (120) embedded in the sandwich structure of the floor panel are the elements that will give continuity to the vertical stiffeners (320) of the lateral panels.

[0028] Although all the transversal stiffeners are aligned once assembled the car body, there is a discontinuity between those stiffeners in the joint area between panels, thus creating weakened areas in terms of stiffness in those points. To give continuity to the transversal stiffeners in the joints, mating parts (41, 42) are fabricated, that replicate the shape of those stiffeners and are designed to be assembled on the ends of two consecutive stiffeners of adjacent panels, on the inner face of the panels. (Fig 8)

[0029] In the joint between lateral panels and floor panel, since the floor panel is a sandwich part with a substantially flat upper face and with the transversal longerons (120) embedded in the core area of the sandwich, the mating part (42) is assembled over the lower end of the stiffener (320) of the lateral panel, and over the upper face of the floor panel, coincident with the transversal longeron (120) below, with the shape of the mating part (42) transitioning between the shape of the stiffener (320) on the lateral panel and a flat surface when reaching the floor panel.

[0030] By installing these mating parts on the joints between panels, the different stiffeners of each panel are transformed into a frame in the car body (Fig 9). The mating parts may be assembled with adhesives (usually preferred) or fasteners, or a combination of both.DESCRIPTION OF PARTICULAR EMBODIMENTS OF THE INVENTION

[0031] The invention described in previous paragraphs may be implemented with multiple variations in terms of materials or manufacturing processes.

[0032] In a particular embodiment of the invention, the longitudinal beams (110, 210) are composite elements manufactured by pultrusion.

[0033] The transversal longerons (120) embedded in the core area of the sandwich floor panel (10) are beam elements that may have multiple different sections: they may be hollow elements, tube type, with a square or rectangular section, or they may have a section with shape of "H", "C", "omega", etc. These longerons may be metallic, although it is usually preferred to manufacture them in composite materials for weight reasons. In this case, the use of pultrusion as manufacturing method may be preferred in terms of cost.

[0034] In particular embodiments of the invention, the sandwich floor panel may integrate additional longitudinal or transversal beams in the sandwich area, if required to give more stiffness to the panel or to reinforce local areas where concentrated loads are applied. Other types of fittings or reinforcement elements may be also integrated in the floor sandwich structure with the same purpose.

[0035] In the case of the stiffeners integrated in the lateral and roof panels, several alternatives exist both in terms of shape of the section of the stiffeners, and ways to integrate them into the panel.

[0036] Although the stiffeners integrated in the lateral and roof panels could have multiple section shapes, such as sections in "C", "L", "T", among others, the preferred are closed sections, which are usually more easy to integrate during the process of lamination of the panel, and also it is more easy to give them continuity between panels through the joints with the corresponding mating parts (41). For this reason, stiffeners with section in "omega", or "hat", are usually preferred. The section may have vertical or sloped walls, although usually the sloped choice is preferred for manufacturability reasons.

[0037] The stiffeners may be manufactured in different materials: they may be metallic, plastic, or fiber reinforced plastic, among others. The composite (fiber reinforced plastic) option is usually preferred for several reasons: weight, stiffness, and ability to adapt to the form of the panel where it is to be applied, if the surface is not totally flat.

[0038] There are several ways to integrate these stiffeners in the roof and lateral panels: In one embodiment of the invention, both the stiffeners and the panels are manufactured and finished as independent parts, and later joined (bonded or fastened) together as an assembly. In this case, the material of the stiffener can be any.

[0039] In another embodiment, the stiffeners are composite elements that are manufactured and cured as independent parts, and later bonded to the panel during the fabrication of said panel, the panel being later cured after stiffener integration. It is a two-curing step approach, usually called "co-bonding", where a first part already cured is integrated into a second, yet uncured part, and finally curing and bonding the whole assembly in a second curing cycle.

[0040] In another embodiment, the stiffeners are composite elements that are laminated and formed independently, but not cured, and integrated yet uncured into the panel during the panel fabrication process, being later cured this assembly as a single integrated part. This process is usually called "co-curing".

[0041] Finally, in another embodiment, the stiffeners are directly laminated during the panel fabrication, usually including some type of lightweight core inside the stiffener to laminate on it (Fig 10), although removable tools may be temporarily used to laminate the stiffener on them and later removed after curing, leaving empty the core area of the stiffener (Fig 11).

Claims

1. A composite railway car body structure (1) comprising at least two lateral panels (30), one roof panel (20) and one floor panel (10), the panels essentially manufactured in fiber reinforced plastic materials, and also comprising four longitudinal beams (110, 210) located essentially in the corners of the car body structure, the floor panel being a composite sandwich structure comprising a first face of fiber reinforced plastic, a second face of fiber reinforced plastic, and an intermediate core area filled with a lightweight core and also comprising reinforcing elements in the core area, characterized in that • the two upper longitudinal beams (210) are integrated in the laminate of the roof panel (20), • the two lower longitudinal beams (110) are embedded in the core area of the floor sandwich panel (10), • the roof panel (20) includes two longitudinal flaps (230) in its lateral borders for attachment to the lateral panels (30), • the floor panel (10) includes two longitudinal flaps (130) in its lateral borders for attachment to the lateral panels (30), and • the lateral panels (30) are assembled to the roof (20) and floor (10) panels by means of a lap joint between the lateral panels and the longitudinal flaps (130, 230) of the floor and roof panels.

2. The railway car body structure according to claim 1 wherein the lap joints between the panels are reinforced by applying at least one layer of composite material as reinforcement (400) on the joint area.

3. The railway car body structure according to any of the claims 1 or 2 wherein the lateral panels (30) integrate vertical stiffeners (320) and the roof panel (20) integrates transversal stiffeners (220).

4. The railway car body structure according to claim 3 wherein the vertical stiffeners (320) of the lateral panels (30) and the transversal stiffeners (220) of the roof panel are located to be substantially aligned when the roof panel is attached to the lateral panels, and mating parts (41) are assembled over the end of consecutive stiffeners on adjacent roof and lateral panels to give continuity to those stiffeners in the joint between the panels.

5. The railway car body structure according to claim 4 wherein the floor panel (10) comprises transversal longerons (120) embedded in the core area of the sandwich that are located to be substantially aligned with the vertical stiffeners (320) of the lateral panels when the floor panel is attached to the lateral panels, and mating parts (42) are assembled over the lower end of the vertical stiffeners (320) on lateral panels (30) and over the upper face of the floor panel (10), coincident with the transversal longeron (120) below, to give continuity to the stiffeners (320) with the longerons (120) in the joint between the panels, and thus forming closed frames in the final car body structure.

6. A manufacturing process for the railway car body structure according to any of the claims 1 to 5 comprising the following steps: • manufacturing the two upper (210) and two lower (110) longitudinal beams • manufacturing the composite roof panel (20) integrating the two upper longitudinal beams (210) in the laminate of the panel, • manufacturing the composite floor panel (10) embedding the two lower longitudinal beams (110) in the core area of the sandwich, • manufacturing the composite lateral panels (30), and • assembling the panels together making lap joints between the lateral panels and the floor and roof panels, using adhesives, fasteners or a combination of both in the lap joint, to form the railway car body structure (1).

7. The manufacturing process according to claim 6 wherein at least one of the longitudinal beams (110, 210) is manufactured in composite materials.

8. The manufacturing process according to claim 7 wherein the composite longitudinal beams are manufactured by pultrusion process.

9. The manufacturing process according to any of the claims 6 to 8 further comprising the step of reinforcing the joints between panels by applying at least one layer of composite material over the joint areas.

10. The manufacturing process according to any of the claims 6 to 9 further comprising the step of integrating transversal stiffeners (220) in the roof panels (20) and vertical stiffeners (320) in the lateral panels (30).

11. The manufacturing process according to claim 10 wherein the stiffeners are co-bonded to the composite panels.

12. The manufacturing process according to claim 10 wherein the stiffeners are co-cured with the composite panels.