Roof hood for a rail vehicle

Abstract

The invention relates to a roof hood (1) for a rail vehicle, said rail vehicle comprising planar side walls and a planar roof (2), wherein a sloping part (3) is provided at the transition from the side walls to the roof (2), wherein the roof hood (1) is designed for fastening to the roof (2) of the rail vehicle and is curved upward and extends from the sloping part (3) of one longitudinal side of the rail vehicle to the sloping part (3) of the opposite longitudinal side.

Description

[0001] Description Roof hood for a rail vehicle Technical field The invention relates to a roof hood for a rail vehicle for reducing sensitivity to crosswinds, in particular for a passenger rail vehicle. State of the art Rail vehicles are exposed to aerodynamic forces as a result of wind. The effectively acting wind is made up of the airstream due to movement and the natural ambient wind. If this wind does not occur as a pure headwind, but as a crosswind with a speed component normal to the longitudinal axis, this can lead to tipping over despite the generally high mass of a rail vehicle. This danger exists particularly in vehicles with unfavorable aerodynamic properties, for example a large wind attack surface, low weight and high travel speed, due to the superposition of the airstream and ambient wind.In general, the rail vehicle is subjected to aerodynamic drag due to the headwind, a lateral force due to the crosswind, and a lift force due to the airflow. In addition, roll, pitch, and yaw moments act due to the uneven aerodynamic force distribution. Crosswind sensitivity is expressed in particular by the roll moment on the vehicle about its longitudinal axis or a tipping moment about the leeward (downwind) rail. Lift forces have a secondary effect by reducing the grip of the wheels on the rails. One known solution for reducing this sensitivity is the addition of mass to the underframe. Other known measures involve modifications to the chassis characteristics for optimized load distribution across both bogies.Known solutions to this problem aim at aerodynamic measures to improve the crosswind stability of high-speed vehicles, in particular at reducing the lift at the front of the vehicle. In contrast, conventional vehicles, which typically travel at up to 200 km / h, and especially those reinforced for speeds of up to 230 km / h, usually have a cuboid-shaped car body and therefore exhibit different aerodynamic behavior due to their blunt shape. The car body is often constructed using lightweight construction techniques, which can also lead to increased crosswind sensitivity in these vehicles. Vehicles whose car bodies have a chamfer at the transition between a side wall and the roof have proven to be particularly critical with regard to their crosswind sensitivity.Since vehicles designed in this way are already in use in large numbers, a solution for retrofitting is also very advantageous, as this makes it possible to react to changes in weight and an extension of the driving speed range. Furthermore, the structural integrity, as well as the pressure and watertightness of a rail vehicle body, should not be impaired and only a low outlay for assembly equipment should arise. Description of the invention The invention is therefore based on the object of specifying a roof hood for a rail vehicle which reduces the sensitivity to crosswinds, i.e. reduces the tipping moment on the car body caused by incident crosswinds. This object is achieved by a roof hood with the features of claim 1 and a rail vehicle according to claim 7. Advantageous embodiments are the subject of subordinate claims.According to the basic idea of ​​the invention, a roof hood for a rail vehicle is described, wherein the rail vehicle comprises flat side walls and a flat roof, wherein a bevel is provided at the transition from the side walls to the roof, and wherein the roof hood is designed for attachment to the roof of the rail vehicle and is curved upwards and extends from the bevel of one long side of the rail vehicle to the bevel of the opposite long side. A flat roof can also be formed from the corrugated sheet metal commonly used in rail vehicles or from a sheet metal reinforced with ribs. This offers the advantage of being able to positively influence the aerodynamic properties of a rail vehicle with regard to the tipping moment occurring in crosswinds, so that this tipping moment is reduced compared to rail vehicles without a roof hood at the same flow velocity.According to the invention, a roof hood is constructed in the form of a flat component with a curvature, which is designed for attachment to the roof area of ​​a rail vehicle. The roof hood according to the invention is intended in particular for rail vehicles with flat side walls and a flat roof, which have a bevel at the transition from the side walls to the roof. This feature causes disadvantageous crosswind properties, so that a roof hood can be used to improve this. A particularly advantageous property of the invention is that the roof hood can also be used to retrofit existing vehicles or vehicles for which the basics have already been developed, whereby only minimal modifications to the existing vehicles are required.The roof hood can be used advantageously, particularly in train compositions with a control car, which, in contrast to a locomotive, has a significantly lower mass and is therefore more sensitive to crosswinds. The cross-section of the roof hood is designed as an upwardly curved component, with this curvature being constant over the entire length of the roof hood. According to a first embodiment, the curvature is composed of a sequence of at least three radii, with the first and last radii each starting at a bevel and the construction being symmetrical. A further preferred embodiment of the roof hood provides that the curvature of the roof hood follows a section of the circumference of an ellipse. The transition between the bevel of the car body of the rail vehicle and the roof hood is crucial for the optimal function of the roof hood.It is particularly advantageous if the slope of the roof hood connects tangentially to that of the bevel. Even a deviation of up to 10° from the tangential to the horizontal can still result in sufficiently improved aerodynamic properties. If the transition radii are too small or, in extreme cases, if the transition between the bevel and the roof is sharp, the flow will separate in this area on the upwind side. This separation causes, among other things, a leeward vortex next to the vehicle which greatly reduces crosswind stability. The design of the roof hood prevents this separation on the one hand, but also exploits the Coandă effect, which creates negative pressure when flows are applied along a convex geometry. Because it occurs on the upwind side in this case, it promotes the crosswind stability of the vehicle.The roof hood can preferably extend over the entire length of the rail vehicle, thereby allowing particularly advantageous crosswind properties to be achieved. If this is not possible for certain reasons, such as the requirement for roof superstructures, the roof hood can only extend over a specific section of the length of the rail vehicle. Particularly in the case of control cars, it is advantageous to arrange the roof hood close to the front end, as this improves the crosswind properties of the vehicle front, which is particularly sensitive to crosswinds, and the remaining sections of the roof can remain free for roof superstructures such as pantographs, antennas, etc. The structure of a roof hood can advantageously be designed as a sheet metal construction consisting of frames and bows covered with sheet metal, whereby additional longitudinal stiffeners can also be arranged to improve accessibility.Furthermore, the aerodynamic properties of a roof hood according to the invention can be improved if panels are provided on its end faces, which direct the airflow around the gap between the roof and the underside of the hood. In this way, disruptive turbulence and noise can be prevented. Such panels, preferably wedge-shaped, can be formed integrally into the roof hood or as a separate component. It is aerodynamically advantageous to design the ends of the roof hood facing the end faces of the rail vehicle in a wedge-shaped manner. For this purpose, for example, a roof hood front beveled at an acute angle can be provided. Alternatively, this front can also be rounded. Such a roof hood end can preferably be formed as a deep-drawn part.A preferred embodiment of the invention provides for the roof hood to be constructed in two parts, in the form of a first and a second partial roof hood, each partial roof hood being designed separately for attachment to the roof of the rail vehicle and each partial roof hood being attached to a respective bevel of the rail vehicle, and an area on the roof of the rail vehicle remaining uncovered by the split roof hood. This provides the advantage of being able to leave large parts of the roof unchanged, so that roof structures such as antennas can continue to be provided without modifications. The aerodynamic properties of such a split roof hood are only slightly worse than a continuous roof hood and significantly better than vehicles without this aerodynamic aid.Such a split roof hood is particularly advantageous for retrofitting existing rail vehicles, as it only needs to be installed in the area where the side wall slopes down to the roof. However, roof superstructures are not commonly installed in this position, so they do not need to be taken into account. Such partial roof hoods are particularly advantageous for roofs made of corrugated sheet metal (or sheet metal reinforced with ribs). The partial roof hood can then be pulled over the ribs of a slope up to a rib of the flat roof. The ribs then close off the partial roof hood at the sides. The roof hood can be made from all materials commonly used in rail vehicle construction, such as steel, stainless steel, or light metal. It can also be made from plastic, for example, glass-fiber reinforced plastic.The roof hood should preferably be attached with minimal interference with the vehicle structure; in particular, recesses and holes in the outer skin of the rail vehicle should be avoided. While screwed, riveted, or similar types of connections are possible, adhesive or welded connections are preferable for ensuring the permanent tightness of the vehicle's outer skin. A free air passage must be provided in the gap between the underside of the roof hood and the roof. This ventilation reduces the accumulation of water and the associated risk of corrosion. Another option for implementing a roof hood, or a partial roof hood, is the use of solid plastic elements.The inner contours facing the rail vehicle can be precisely adapted to the outer contours of the rail vehicle, thus eliminating problems with water ingress, thermal expansion of air in a closed cavern, and electrical grounding. Alternatively, the area between a partial roof hood and the roof of a rail vehicle can be filled with foam. For this purpose, a foam with hydrophobic properties that does not expand upon curing is used. A roof hood can be attached, for example, using at least two C-rails arranged on the roof parallel to the longitudinal axis of the rail vehicle and into which sliding nuts can be inserted. The roof hood itself has corresponding holes through which screw connections can be made.It is essential to suitably close these holes after creating a screw connection so that the pressure field acting on the rail vehicle remains undisturbed and the advantageous aerodynamic effect of a roof hood is not reduced. Alternatively, the roof hood can be attached using brackets, consoles or suitably designed holders. However, modern adhesive bonding processes also allow a roof hood to be attached solely using adhesive bonds. Since adhesive bonds generally have an electrically insulating effect, appropriate precautions such as ground straps must be taken to ground the roof hood to the rail vehicle body. It is particularly advantageous if the roof hood is connected to the car body using screw connections in addition to an adhesive connection, as this ensures the electrical ground connection.A preferred embodiment of the invention provides for the roof hood to be made from sheet metal that has been bent several times, so that the radii in the cross-section of the roof hood are approximated by a polygonal line. Since the production of a continuously bent sheet metal with several consecutive radii is complex, a roof hood can thus be manufactured more simply and cost-effectively. The bending points are to be positioned so close to one another that such a polygonal sheet can develop practically the same aerodynamic effect as a continuously bent sheet metal. Brief description of the drawings The following show, by way of example: Fig. 1 Rail vehicle body with roof hood. Fig. 2 Rail vehicle body with split roof hood. Fig. 3 Rail vehicle roof with split roof hood, section. Fig. 4 Rail vehicle roof with roof hoods of different curvatures. Embodiment of the invention Fig. 1 shows, by way of example and schematically, a rail vehicle body with a roof hood.An oblique view of a cross-section through a rail vehicle roof is shown, with bevels 3 starting on both sides at the upper end of the side walls, forming the transition to a flat roof 2. The rail vehicle shown as an example is constructed in a differential design from a planked bow-frame construction. The planking is a so-called trapezoidal sheet, which is more stable than a flat sheet. The kink in the course of the planking at the point of transition from the bevel 3 to the flat roof 2 is detrimental to the aerodynamic properties of such a car body with regard to its sensitivity to crosswinds. In the embodiment shown, this is improved by the provision of a roof hood 1. The roof hood 1 is curved upwards and extends from the bevel 3 on one long side of the rail vehicle to the bevel 3 on the opposite long side.The roof hood 1 is shaped such that its slope connects tangentially to the bevel 3. Two C-rails 5 are arranged on the roof 2, by means of which screw connections 7 are established between the roof 2 and the roof hood 1. The roof hood 1 shown in Fig. 1 spans the entire width of the roof 2, making it difficult to provide roof structures such as antennas. To solve this problem, recesses can be created in the roof hood 1 through which these roof structures can penetrate the roof hood 1. It is essential to tightly seal the holes for producing the screw connections 7 after they have been produced, so that the aerodynamic effect of the roof hood 1 is guaranteed.To improve the tightness between the roof hood 1 and the bevel 3, the lateral extensions of the sheet metal of the roof hood 1 can be designed such that they press against the roof when the screw connections 7 are made, thus ensuring a tight connection point. Fig. 2 shows an example and schematically a rail vehicle roof with a split roof hood. It shows a detail of a rail vehicle car body at the transition point from a bevel 3 to a flat roof 2, with a partial roof hood 4 arranged at this position. Such a partial roof hood 4 is also provided at the opposite transition point along the opposite long side of the car body. In Fig. 2, only one side is shown to clarify the illustration. The partial roof hood 4, i.e. the slope of the partial roof hood 4, adjoins the bevel 3 tangentially and extends further over the flat roof 2.The flat roof 2 is then uncovered, and any roof structures provided are therefore not impaired by the partial roof hoods 4. The aerodynamic effect of two partial roof hoods 4 is slightly reduced compared to a continuous roof hood 1, as shown in Fig. 1, but significantly improved compared to a car body without such aerodynamic aids. The exemplary embodiment shown shows a partial roof hood 4 which is connected to the bevel 3 and the roof 2 by means of adhesive connections 6. A C-rail 5 is arranged on the roof 2, wherein the partial roof hood 4 is secured against falling off by means of screw connections 7 and an electrically conductive connection is established between the partial roof hood 4 and the roof 2. In the case of partial roof hoods made of plastic, this earthing connection can be omitted.It is essential that the adhesive connection 6 between the partial roof hood 4 and the bevel 3 is made tight so that at this position no air flow can penetrate into the gap between the partial roof hood 4 and the car body, as this can lead to increased noise and a deterioration in the aerodynamic properties. To drain the cavity between the rail vehicle roof and the roof hood and to equalize pressure due to thermal expansion of the air, openings should therefore preferably be arranged at the front. Fig. 3 shows an example and schematically a rail vehicle roof with a split roof hood in a sectional view. The embodiment from Fig. 2 with partial roof hoods 4 is shown, whereby the sectional view is transverse to the longitudinal direction of the car body. In particular, the positions of the adhesive points 6 and the screw connections 7 to the roof 2 are clearly visible.A partial roof hood 4 according to the invention can be manufactured in one piece from sheet metal and, in contrast to an undivided roof hood 1, as shown in the embodiment in Fig. 1, does not require a supporting structure made of frames and / or bows. Fig. 4 shows an example and schematically a rail vehicle roof with two roof hoods of different curvatures. The transition point between a bevel 3 and a roof 2 is shown in abstraction, with both roof hoods being designed with an identical radius of the central part 3. The roof hoods differ in their curvature at the transition to the bevel 3. The first roof hood is attached tangentially to the bevel 3, so that its first radius R1 follows the tangent T. The second roof hood has a second radius R2 at this transition point, which follows a line T - 10° that is 10 degrees flatter than the horizontal.

[0002] List of designations 1 Roof hood 2 Flat roof 3 Bevel 4 Partial roof hood 5 C-rail 6 Adhesive connection 7 Screw connection R1 First radius R2 Second radius R3 Radius of the middle part T Tangent T-10 ° Tangent - 10 °

Claims

1. Roof hood (1) for a rail vehicle, which comprises flat side walls and a flat roof (2), wherein a bevel (3) is provided at the transition from the side walls to the roof (2), characterized in that the roof hood (1) is designed for attachment to the roof (2) of the rail vehicle and is curved upwards and extends from the bevel (3) of one long side of the rail vehicle to the bevel (3) of the opposite long side, wherein the slope of the roof hood (1) at the connection point to the bevel (3) connects to the bevel (3) between tangentially and up to 10° from the tangential towards the horizontal.Roof hood (1) for a rail vehicle according to claim 1, characterized in that the curvature of the roof hood (1) follows a sequence of at least three radii, wherein the first and the third radii, which each start at a bevel (3), are identical, so that the roof hood has a symmetrical cross-section.

3. Roof hood (1) for a rail vehicle according to claim 1 or 2, characterized in that the curvature of the roof hood (1) follows a section of a circumferential line of an ellipse.

4. Roof hood (1) for a rail vehicle according to one of claims 1 to 3, characterized in that. the roof hood (1) is designed in two parts in the form of a first and a second partial roof hood (4), wherein each partial roof hood (4) is designed separately for attachment to the roof (2) of the rail vehicle and each partial roof hood (4) is attached to a respective bevel (3) of the rail vehicle, and wherein an area on the roof (2) of the rail vehicle remains uncovered by the divided roof hood.

5. Roof hood (1) for a rail vehicle according to one of claims 1 to 4, characterized in that the roof hood (1) is designed as a sheet metal construction comprising frames and bows covered with sheet metal.

6. Roof hood (1) for a rail vehicle according to one of claims 1 to 5, characterized in that the curvature of the roof hood (1) is approximated by means of a polygonization from a multiply bent sheet metal. 7.Roof hood (1) for a rail vehicle according to one of claims 1 to 6, characterized in that the ends of the roof hood (1) facing the end faces of the rail vehicle taper in a wedge shape.

8. Rail vehicle comprising flat side walls and a flat roof (2), wherein a bevel (3) is provided at the transition from the side walls to the roof (2), characterized in that. for fastening a roof hood (1), at least two C-rails (5) are arranged on the roof parallel to the longitudinal axis of the rail vehicle.

9. Rail vehicle comprising a roof hood (1) according to one of claims 1 to 7, characterized in that the roof hood (1) extends over the entire length of the rail vehicle.

10. Rail vehicle comprising a roof hood (1) according to one of claims 1 to 7, characterized in that the roof hood (1) extends over a specific section of the length of the rail vehicle.

11. Rail vehicle according to claims 8 to 10, characterized in that the rail vehicle is designed as a control car.

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