Device for reducing the air resistance of a vehicle

Abstract

The invention relates to a device (1) for reducing the air resistance of a vehicle (100), wherein the device (1) is intended for arrangement at the rear of the vehicle (100), the device comprising at least one first attachment element (11) and at least one second attachment element (12) as well as at least two air guide elements (13) which are designed in the manner of a strip and have an element length. A first side of the air guide elements (13) in the direction of the element length is connected or connectable to the first attachment element (11), and a second side of the air guide elements (13) in the direction of the element length is connected or connectable to the second attachment element (12). A distance exists between the air guide elements (13) in a direction perpendicular to the element length. The invention further relates to a vehicle (100) with a device for reducing air resistance and to a method for changing the air resistance of a vehicle (100).

Description

The invention relates to a device for reducing the air resistance of a vehicle, wherein the device is provided for arrangement at the rear of the vehicle, the device comprising at least one first attachment element and at least one second attachment element and at least two air guiding elements, which are designed in the manner of a band and have an element length. A first side of the air guiding elements in the element length direction is connected or connectable to the first attachment element and a second side of the air guiding elements in the element length direction is connected or connectable to the second attachment element. There is a distance between the air guiding elements in a direction perpendicular to the element length. The invention further relates to a vehicle having a device for reducing the air resistance and to a method for changing the air resistance of a vehicle.Once a vehicle is moving, energy must be applied to overcome the drag that acts against the moving vehicle in the opposite direction to the direction of travel. The energy required to overcome the air resistance must be provided by the drive of the vehicle. The energy required to overcome the air resistance enters into the performance balance of the vehicle as a power loss and must be provided by an equivalent of fuel or electrical energy for moving the vehicle. FIG. 3 shows, for example, a vehicle according to the prior art, which has a large and easily accessible storage space at the rear. The air flow which flows around the moving vehicle is symbolized in regions by arrows. It can be clearly seen that behind the stowage space at the rear of the vehicle a swirling is formed which increases the air resistance of the vehicle and brings about an increased energy requirement. It is thus advantageous to reduce the air resistance of a vehicle, since this requires less energy to be provided for moving the vehicle. There are various approaches to reduce the drag of a vehicle. For example, planar spoilers can be arranged on the outside of the vehicle, which guide the air flow around the moving vehicle and thereby reduce turbulence. Furthermore, surfaces of the vehicle can be provided with fine structures which improve the flow behavior of an air flow over these surfaces. In principle, a streamline configuration, in particular a drop-shaped configuration, of the entire vehicle is advantageous in order to achieve a low-swirling flow around the moving vehicle. However, such a streamline configuration often encounters other vehicle requirements, such as the need for a high and wide cargo space at the rear of the vehicle or a short overall length of the vehicle.U.S. Pat. No. 10,850,780 B1 describes a system which reduces the air resistance behind a trailer. The system includes one or more inflatable objects mounted at the rear of the trailer. The shape of these objects can be changed by filling them with air. When the vehicle is stationary or during slow travel, the air can be completely removed from these objects, as a result of which they can be stored in a space-saving manner at the rear of the trailer.DE 20 2014 007 684 U1 describes a device for improving aerodynamics in a vehicle. The device comprises an inflatable flow guide means made of a flexible material. This flow guiding means is shaped like a backpack for the vehicle in the inflated state, which reduces turbulence at the rear of a vehicle. When not in use, the flow guide can be placed on the rear of the vehicle in a space-saving manner.DE 10 2009 014 860 A1 describes a flow guidance device of a vehicle that reduces the flow resistance. This device comprises one or more air guide surfaces, which can be adjusted in their orientation to the vehicle by actuators, such as hydraulic cylinders, for example. The device further comprises sensors which record the current flow situation around the vehicle and a controller which adapts the orientation of the air guide surfaces to this current flow situation.DE 10 2006 059 062 A1 describes a net-shaped wind deflector for a vehicle. The wind deflector extends from an upper edge of the rear window to a rear edge of the vehicle body arranged at the vehicle end. The wind deflector can be lowered on one of its sides together with the rear window. The wind deflector can be a flexible sheet-like structure, for example a plastic net, which extends directly between two attachment elements on the vehicle.The object of the invention is to propose solutions with which the air resistance of a vehicle can be reduced in a simple manner, wherein these solutions should be adaptable to different vehicle types with little effort.This object of the invention is achieved by a device for reducing the air resistance of a vehicle, wherein the device is provided for arrangement at the rear of the vehicle, the device comprising:at least one first attachment element, which is connectable to the vehicle,at least one second attachment element, which is connectable to the vehicle,at least two air guiding elements which are configured in the manner of a strip and have an element length which is greater than an element width and an element thickness by at least a factor of 10, wherein a first side of the air guiding elements in the direction of the element length is connected or connectable to the first attachment element and a second side of the air guiding elements opposite the first side is connected or connectable to the second attachment element in the direction of the element length, and a distance exists between the air guiding elements in a direction perpendicular to the element length.According to the invention, the air guiding elements are designed to be elastically deformable, wherein the air guiding elements are arched and at least partially elastically prestressed between the first attachment element and the second attachment element, and the air guiding elements are situated completely between the first attachment element and the second attachment element in this prestressed state.The device according to the invention is provided to be arranged at the rear of a vehicle in order to reduce its air resistance during a movement of the vehicle. The device is suitable for significantly reducing the air resistance coefficient, also called cW value.The device according to the invention comprises a first attachment element and a second attachment element, which are provided to fasten the device to a vehicle. At the same time, the attachment elements serve for fastening the air guiding elements of the device. The device comprises at least two air guiding elements, preferably more than two air guiding elements are provided. The air guiding elements are configured in the manner of bands. In this case, band-like is to be understood as meaning that the air guiding elements have an element length in their longitudinal direction which is significantly greater than their element width and element thickness oriented perpendicularly to the element length. Strap-like is also to be understood as elongated, elongated, rod-like or rope-like. The band-like air guiding elements can be designed to be rigid or elastic and / or plastically deformable. These terms rigid and deformable refer here to a use case of the device in the connected state with a vehicle. In this application, only the own gravity and forces generated by an air flow during movement of the vehicle act on the air guiding elements. The element length of the air guiding elements is greater than the element width and the element thickness by at least a factor of ten. It is also possible that the element length differs from the element width and the element thickness by an even greater factor, for example by a factor of 15, 20, 50 or 100. The air guiding elements are connected or connectable with mutually opposite sides, viewed along the element length, on the one hand to the first attachment element and on the other hand to the second attachment element. Connectable is to be understood in this case as meaning that it can be provided that the air guiding elements can be separated or removed from the first attachment element and / or from the second attachment element as required. Such an embodiment can be used, for example, if the air guiding elements are to be removed or stowed in certain application cases. According to the invention, the air guiding elements are arranged in a direction perpendicular to their element length such that there is a distance between them. This spacing brings about a gap between adjacently arranged air guiding elements. In the application in which the device is fastened to a vehicle, the distance or the gap between adjacent air guiding elements extends in the horizontal direction. It is possible for the distance between adjacent air guiding elements to extend along the entire element length.According to the invention, a plurality of slender, strip-like air guiding elements which are arranged at a distance from one another together form a structure which brings about the approach of a vehicle which is equipped with the device to a streamline shape. From the prior art, structures are known which are formed by a gapless membrane which are arranged behind the vehicle in three-dimensional form in the manner of a backpack. According to the invention, however, a similarly shaped structure is formed by a plurality of individual air guiding elements, between which gaps or spacings exist. It has surprisingly been found that such a plurality of individual air guiding elements behave in the air flow behind a vehicle very similar to a self-contained structure and significantly reduce turbulence behind the rear of the vehicle. A distance of a few centimeters, for example 5, 3 or 1 cm, can be selected as the distance between adjacent air guiding elements. The distance can also correspond to the element width and / or the element thickness of the air guiding elements.An advantage of the device according to the invention is that it is possible to see through the distances between the air guiding elements, which significantly improves the view to the rear from the vehicle during travel. Moreover, in the device according to the invention, less material is required compared to a closed membrane fastened to the rear of the vehicle, whereby this is lighter and can be stored more easily. Due to the band-like embodiment of the air guiding elements, these can be fastened to the rear of the vehicle in a simplified manner. Furthermore, this belt-like embodiment optionally also allows adjustability of the free element length of the air guiding elements. Thus, for example, it can be provided in a simple manner that the free element length is extended when the vehicle is travelling faster, whereby a drop shape at the rear of the vehicle is approximated. If the vehicle is subsequently moved or shut down again more slowly, the free element length can be reduced in a simple manner, so that the air guiding elements bear firmly against the rear of the vehicle and do not impede the operation of the vehicle, in particular of the tailgate. Furthermore, the device according to the invention can be easily adapted to different vehicle types, for example by a simple adjustment of the element length of the air guiding elements. The device according to the invention is suitable for attachment to conventional passenger cars, SUVs or else container-like shaped trailers or semi-trailers of trucks.In one embodiment, it is provided that the element length of the air guiding elements is greater than the direct distance between the first attachment element and the second attachment element. The direct distance between the first attachment element and the second attachment element is the shortest distance between these elements. Because the element length of the air guiding elements is greater than this distance, partial regions of the air guiding elements protrude counter to the direction of travel via a direct connecting line between the first attachment element and the second attachment element. For example, the air guiding elements can extend in an arc shape between the first attachment element and the second attachment element. As a result of this protrusion or the arc shape, the device at the rear of the vehicle is given a shape which narrows counter to the direction of travel and which reduces or completely prevents the formation of vortices of air behind the vehicle.In one embodiment, it is provided that more than two air guiding elements are provided, wherein the element length of at least two air guiding elements differs from one another. The device preferably comprises more than two air guiding elements. The element length of these air guiding elements differs from one another. For example, in a direction perpendicular to the direction of travel of the vehicle to which the device is fastened, air guiding elements with a smaller element length can be arranged on the outside than on the inside and / or in the middle of the vehicle. The element length of the individual air guiding elements can easily be used to adjust or influence the shape of the device in a plan view from above of the vehicle. The element length of the air guiding elements can be permanently identical or, in particular, can be made adjustable during the travel of the vehicle.In one embodiment, it is provided that the distance between the air guiding elements extends in a direction perpendicular to their element length in the direction of an extension direction and more than two air guiding elements are provided, which are arranged next to one another in the extension direction at distances from one another, wherein the element length of the air guiding elements arranged on the outside in the extension direction is smaller than the element length of air guiding elements arranged between the air guiding elements arranged on the outside in the extension direction. The term extension direction is to be understood as an imaginary direction which extends perpendicular to the element length of the air guiding elements. The distance between adjacent air guiding elements is defined along this direction of extension. In a state of the device mounted on a vehicle, the direction of extension is preferably oriented perpendicular to the direction of travel of the vehicle. The element width of the air guiding elements can be oriented in the direction of the direction of extension. Preferably, more than two air guiding elements are arranged in the extension direction, each with a distance between adjacent air guiding elements. The element length of the air guiding elements differs here: the air guiding elements arranged on the outside in the direction of extension have a smaller element length than the air guiding elements arranged in the middle of the device in the direction of extension. In this way, the vehicle-mounted device simulates a drop shape in a top view of the vehicle, which is particularly effective against the generation of vortices behind the rear of the vehicle. The air guiding elements with the largest element length are preferably arranged in the middle in the direction of extension. From this center, the element length of the air guiding elements is gradually reduced in the direction of extension outwards. The air guiding elements with the shortest element length are arranged on the outside in the direction of extension.In one embodiment, it is provided that at least one transverse connection is provided, which connects two air guiding elements in a direction perpendicular to their element length, wherein the transverse connection only partially covers the distance or the gap between the air guiding elements in a direction perpendicular to the element length. It is also possible for the air guiding elements to be connected to one another in a direction perpendicular to their element length by one or more transverse connections. Such a transverse connection in this case bridges in regions the distance between adjacent air guiding elements in a direction perpendicular to their element length. Such a transverse connection fixes the overall shape of the air guiding elements. However, the transverse connection or the transverse connections are dimensioned such that they do not completely cover the distance or the gap between adjacent air guiding elements. Gaps thus remain between adjacent air guiding elements, which can be used, for example, for viewing through the entirety of the air guiding elements. It is also possible to connect a plurality of transverse connections to the air guiding elements at a distance from one another and parallel to one another. In this way, a net-like structure is formed.In one embodiment, it is provided that the air guiding elements are of rigid design and are arcuate, in particular as viewed from the direction of extent, wherein the air guiding elements are rigidly connected or connectable to the first attachment element and the second attachment element or the air guiding elements are connected or connectable to the first attachment element and the second attachment element in a movably mounted manner. In this embodiment, the air guiding elements are designed to be rigid in the application case, i.e. in a case in which the device is mounted on a vehicle and is not loaded by any forces other than by the forces which arise in connection with the flow through air. This means that the shape of the air guiding elements does not change during the travel of the vehicle. When viewed from the side, the air guiding elements are designed in an arc shape, wherein the curvature of the arc extends away from the first attachment element and from the second attachment element. When the device is mounted, the curvature of the arc is directed away from the vehicle in a direction opposite to the direction of travel. The air guiding elements can be rigidly connected to the attachment elements. Alternatively, the air guiding elements can also be rotatably connected to the attachment element via a joint. In the rotatable embodiment, the rigid air guiding elements can move about an axis of rotation which is oriented perpendicularly to the direction of travel and to the direction of extension, for example when the vehicle is cornering. This embodiment with rigid air guiding elements is particularly well suited for smaller applications, for example for bridging a rear window of a vehicle. Due to the fact that hardly any or no turbulence occurs within the space bounded by the air guiding elements due to the device, the device effectively protects vehicle parts which are located within this bounded space from dirt. For example, the device can contribute to protecting a rear window of the vehicle arranged underneath from dirt. In addition, the device can also be used to give a vehicle a previously unknown, novel appearance.According to the invention, it is provided that the air guiding elements are designed to be elastically deformable, wherein the air guiding elements are arcuate and at least partially elastically prestressed between the first attachment element and the second attachment element, and the air guiding elements are located completely between the first attachment element and the second attachment element in this prestressed state, in particular wherein, when the first attachment element is arranged in the vertical direction above the second attachment element, the air guiding elements are arranged completely between the first attachment element and the second attachment element in the vertical direction. In this embodiment, the air guiding elements are elastically deformable and, in the assembled state, are elastically prestressed between the first attachment element and the second attachment element. In this mounted state, the air guiding elements have an arc shape, wherein the curvature of the arc points away from the attachment elements in the opposite direction to the direction of travel of the vehicle. Due to the elastic prestress of the air guiding elements, these are arranged completely between the first attachment element and the second attachment element in the vertical direction. The elastic prestress serves to prevent the air guiding elements from hanging down on account of their own gravity. The elastic prestress has the effect that the air guiding elements protrude, counter to the direction of travel, by their own rigidity beyond the vehicle on which the device is mounted. As soon as an air flow acts on the air guiding elements during the travel of the vehicle, these can further elastically deform depending on the forces occurring and thus adapt their shape. An elastic deformability of the air guiding elements in the assembled state between the attachment elements can be provided both along their element length and in the direction of extension. Because the air guiding elements of this embodiment are not rigid, they can adapt to the current driving situation of the vehicle. Furthermore, the air guiding elements likewise behave elastically in the rear region of the vehicle in the event of an accident of the vehicle. As a result, accident encounters and also the vehicle itself are well protected against damage and from injury. An embodiment with elastically prestressed air guiding elements can be used particularly well for devices which cover the entire rear of the vehicle in the vertical direction.In one embodiment, it is provided that the air guiding elements are designed to be elastically deformable, wherein the first attachment element and / or the second attachment element comprise a drawing-in device which is configured to draw in or discharge at least part of the air guiding elements as required, whereby the partial region of the element length of the air guiding elements, which is located outside and between the first attachment element and the second attachment element, is designed to be adjustable. In this embodiment, the partial region of the element length of the air guiding elements, which is located between the first attachment element and the second attachment element, is designed to be adjustable. This partial region can also be referred to as the free element length. To set this free element length, at least one drawing-in device is provided, which, for example, rolls up the air guiding elements as required and draws them into a mounting element. In practice, the air resistance only has a significant effect on the energy consumption of the vehicle at higher speeds, for example from 80 km / h. In this embodiment, the device for reducing the air resistance can be configured only at higher speeds in such a way that the air guiding elements at the rear of the vehicle improve the streamline shape and thus reduce the air resistance. This can be done by increasing the free element length during faster travel, whereby the device protrudes further beyond the vehicle in the opposite direction to the direction of travel. In this embodiment, the air guiding elements can be elastically prestressed as well as have no prestress. In the second case, the air guiding elements are cable-like and are held in their position behind the vehicle only by the air flow during more rapid travel. If the travel speed of the vehicle is reduced, the air guiding elements can be retracted by the retraction device. This has the advantage that, during slow travel of the vehicle or when the vehicle is stationary, the device does not protrude beyond the rear of the vehicle, or only protrudes slightly. In this way, the length of the vehicle is reduced, which facilitates, for example, parking or access to the tailgate. In particular, in city traffic in which the vehicle is usually traveling only at low speeds, the overall length of the vehicle can be reduced in this embodiment. At higher speeds, which usually occur on the country road or on a freeway, the element length of the air guiding elements can be increased in order to significantly reduce the air resistance of the vehicle. Optionally, in this embodiment it can be provided that the air guiding elements can be separated from the first attachment element or the second attachment element. In the case of an arrangement of the intake device on the attachment element which lies opposite the attachment element from which the air guiding elements can be separated, the air guiding elements can be completely intakeed, as a result of which they can hardly be seen on the vehicle. In this optional embodiment, the accessibility to the rear of the vehicle is particularly good. To activate the device, the air guiding elements can then be pulled out of the attachment element with the drawing-in device and again connected to the other attachment element.The object of the invention is furthermore achieved by a vehicle having a device for reducing the air resistance according to one of the embodiments described above, wherein the device is arranged at the rear of the vehicle and the first attachment element and the second attachment element are fixed to the vehicle, wherein the first attachment element is arranged above the second attachment element in the vertical direction and the distance between the air guiding elements is oriented in a direction perpendicular to the element length in the horizontal direction. The vehicle according to the invention is based on a known vehicle which has a device according to the invention for reducing the air resistance. The vehicle can be, for example, a passenger car, an SUV or else a transporter or truck. The device is fastened to the rear, the roof and / or the underbody of the vehicle by the first attachment element and the second attachment element. In the application case, the air guiding elements protrude beyond the rear in the opposite direction to the direction of travel of the vehicle and in this case in their entirety approach the shape of the vehicle to a streamline drop shape. The device can be easily connected to the vehicle and thus the air resistance of the vehicle can be significantly reduced in a simple manner.Finally, the object of the invention is also achieved by a method for changing the air resistance of a vehicle with a device for reducing the air resistance of a vehicle, wherein the device is arranged at the rear of the vehicle, the device comprising:at least one first attachment element, which is connectable to the vehicle,at least one second attachment element, which is connectable to the vehicle,at least two air guiding elements which are configured in the manner of a strip and have an element length which is greater than an element width and an element thickness by at least a factor of 10, wherein a first side of the air guiding elements in the direction of the element length is connected or connectable to the first attachment element and a second side of the air guiding elements opposite the first side is connected or connectable to the second attachment element in the direction of the element length and there is a distance between the air guiding elements in a direction perpendicular to the element length, wherein the air guiding elements are designed to be elastically deformable, wherein the first attachment element and / or the second attachment element comprise a drawing-in device which is configured to draw in or output at least a part of the air guiding elements as required, whereby the partial region of the element length of the air guiding elements which is located outside and between the first attachment element and the second attachment element is designed to be adjustable, the method comprising the method steps: A) determining the travel speed of the vehicle, B) continuously adapting the partial region of the element length of the air guiding elements, which is located outside and between the first attachment element and the second attachment element, depending on the ascertained travel speed of the vehicle by the intake device, wherein this adaptation takes place in steps or continuously to different travel speeds, in particular wherein the partial region of the element length of the air guiding elements, which is located outside and between the first attachment element and the second attachment element, is enlarged as the travel speed increases.The method according to the invention serves to set the air resistance of a vehicle as a function of the travel speed of the vehicle. To carry out the method, a vehicle is used which has a device for reducing the air resistance. This device comprises a draw-in device which enables adjustability of the free element length of the air guiding elements. The air guiding elements can be elastically prestressed between the attachment element or have no elastic intrinsic tension.In a first method step A), the travel speed of the vehicle is determined, in particular continuously, which can be effected, for example, by conventional sensor systems of the vehicle.In a second method step, in particular also continuously, the sub-region of the element length of the air guiding elements is adapted, which is located outside and between the first attachment element and the second attachment element. This adaptation of the free element length is effected by the infeed device, which is preferably controlled by a controller. In this control, different relationships or links between the current travel speed and the free element length of the air guiding elements can be stored. For example, the free element length can be extended from a specific speed limit, for example 80 km / h. Alternatively or additionally, the free element length can be adapted in steps or continuously to different travel speeds. The free element length is preferably increased as the travel speed increases, as a result of which the device protrudes further to the rear beyond the vehicle at a higher travel speed and thus significantly reduces the turbulence of air behind the vehicle.Features, effects and advantages disclosed in connection with the device and the vehicle are also considered to be disclosed in connection with the method. The same applies in the opposite direction, features, effects and advantages which are disclosed in connection with the method, are also considered to be disclosed in connection with the device and the vehicle.The invention is schematically illustrated in the drawings by way of embodiments and will be further described with reference to the drawings. The following are shown: FIG. 1 is a schematic perspective view of a vehicle in an embodiment according to the invention, FIG. 2 shows a schematic side view of a vehicle in an embodiment according to the invention, FIG. 3 shows a schematic side view of a vehicle according to the prior art.FIG. 1 shows a schematic, perspective view of a vehicle 100 in an embodiment according to the invention. The vehicle 100 shown is an SUV which has a wide, steeply sloping rear. A device 1 for reducing the air resistance of the vehicle 100 is mounted on the rear of the vehicle 100.In the embodiment shown, the device 1 comprises a plurality of air guiding elements 13. These air guiding elements 13 are of strip-like design and have an element length which is at least a factor of ten greater than their element width and element thickness. The element length is the extension length in the longitudinal direction of the air guiding elements 13. Between the air guiding elements 13, distances or gaps are present in each case in a direction perpendicular to their element length. In the illustrated state of the device 1 fixed to the vehicle 100, the distances extend in the horizontal direction. The air guiding elements 13 are arranged next to one another in the direction of an extension direction ER, which is oriented perpendicular to the element length. In the assembled state of the device 1 shown, the extension direction ER is oriented horizontally at the same time. The extension direction ER represents the direction in which adjacent air guiding elements 13 are arranged next to one another.A first attachment element 11 is fixed at the top of the vehicle 100 in the vertical direction. A first side of the air guiding elements 13 is connected to the first attachment element 11. A second attachment element 12 is fixed at the bottom of the vehicle 100 in the vertical direction. The second side opposite the first side of the air guiding elements 13 is connected to the second attachment element 12. A free member length of the air guiding members 13 extends arcuately between the first attachment member 11 and the second attachment member 12. The two attachment elements 11, 12 extend in the horizontal direction along the extension direction ER in the illustrated embodiment. The extension direction ER is oriented perpendicular to the direction of travel of the vehicle 100. The element length of the air guiding elements 13 is greater than the direct distance between the first attachment element 11 and the second attachment element 12. In the embodiment shown, the air guiding elements 13 are designed to be elastically deformable. The air guiding elements 13 are elastically prestressed in an arcuate manner between the first attachment element 11 and the second attachment element 12. The air guiding elements 13 have sufficient bending rigidity so that they do not hang downward due to their own gravity, but instead project from the vehicle 100 in an arc shape opposite to the direction of travel of the vehicle 100. The elastic prestress has the effect that the air guiding elements 13 maintain the illustrated shape even when air flows around them during the travel of the vehicle 100. In the vertical direction, the air guiding elements 13 are located completely between the first attachment element 11 and the second attachment element 12. To influence the arc shape, it can optionally be provided that the air guiding elements 13 have a bending stiffness of different magnitude along the element length. The arcuate shape of the mounted air guiding elements 13 approximates the outer contour of the vehicle 100 to a drop shape which is particularly streamlined and ensures low air resistance. In the embodiment shown, the element length, in particular the free element length of the air guiding elements 13, differs from one another between the first attachment element 11 and the second attachment element 12. The air guiding elements 13 arranged on the outside in the direction of extent ER have a shorter element length than the air guiding elements 13 arranged between these air guiding elements 13. From the center to the outside, the element length falls again. The air guiding element 13, which is arranged in the middle in the direction of extension ER, has the largest element length. As a result, the structure formed jointly from all air guiding elements 13 also has a drop shape in a plan view from above of the vehicle, which is particularly streamlined. It can be clearly seen in FIG. 1 that the tailgate of the vehicle can be seen through the distances or gaps between the air guiding elements 13. This makes it possible to look out of the interior of the vehicle 100 through the distances rearward through the device 1. In this way, the device 1 does not obstruct the clear view to the rear from the vehicle 100.FIG. 2 shows a schematic side view of a vehicle 100 in an embodiment according to the invention. In FIG. 2, the same embodiment of a vehicle 100 as in FIG. 1 is shown. In the side view in FIG. 2, the arcuate configuration of the air guiding elements 13 can be seen well. In some areas, an air flow FW is symbolized by arrows above the vehicle 100, as occurs during a movement of the vehicle in the direction of travel, to the left, with reference to FIG. 2. It can be clearly seen that the air flow FW is deflected slightly in its direction by the air guiding elements 13 and finally separates from the vehicle 100 or the device 1 without swirling. The vehicle 100 with the device 1 has a streamline shape in side view which approximates a drop. It can be clearly seen that a view through the distances between the air guiding elements 13 is also possible in the side view. In this way, the device 1 only slightly obstructs the view of other road users past the vehicle 100. In the illustrated embodiment, the air guiding elements 13 have a constant element length that is not variable during the travel of the vehicle 100. Optionally, however, it can be provided that the first attachment element 11 and / or the second attachment element 12 comprises a drawing-in device which is configured to draw in or discharge at least part of the air guiding elements 13 as required, as a result of which the portion of the element length of the air guiding elements 13 which is located outside and between the first attachment element 11 and the second attachment element 12 is designed to be adjustable. As a result, the length in which the device 1 extends behind the tailgate of the vehicle 100 in the opposite direction of travel can be adjusted. Since the air resistance of the vehicle becomes noticeable in particular at high speeds, it is possible in this optional embodiment to increase the structure formed by the device 1 and its air guiding elements 13 at higher speeds in order to reduce the air resistance of the vehicle 100 particularly effectively. Likewise, in this optional embodiment, it is possible to fully retract the air guiding elements 13, so that they rest on the tailgate. In this retracted state, the tailgate is very convenient to reach and the vehicle 100 has a shorter length, which is helpful, for example, when parking.FIG. 3 shows a schematic side view of a vehicle according to the prior art. The vehicle shown corresponds to the vehicle 100 according to the invention shown in FIG. 2, but without a device 1 according to the invention for reducing the air resistance. Similar to FIG. 2, an air flow FW in the rear region of the vehicle is symbolized by arrows when the vehicle is travelling. It can be clearly seen that without the device 1 according to the invention behind the tailgate of the vehicle a swirling is formed, which significantly increases the air resistance of the vehicle. The advantageous effect of the device 1 according to the invention and of the vehicle 100 according to the invention can be seen particularly well in a direct comparison between the illustration in FIG. 2 and the illustration in FIG. 3, which shows the prior art.LIST OF REFERENCE CHARACTERS:1 Device 11 First attachment element 12 Second attachment element 13 Air guiding element 100 Vehicle ER Extension direction FW Air flow

Claims

Device (1) for reducing the air resistance of a vehicle (100), wherein the device (1) is provided for arrangement at the rear of the vehicle (100), the device comprising: - at least one first attachment element (11), which can be connected to the vehicle (100), - at least one second attachment element (12), which can be connected to the vehicle (100), - at least two air guiding elements (13), which are designed in the manner of a band and have an element length, which is greater than an element width and an element thickness by at least a factor of 10, wherein a first side of the air guiding elements (13) is connected or connectable to the first attachment element (12) in the direction of the element length and a second side of the air guiding elements (13) opposite the first side is connected or connectable to the second attachment element (12) in the direction of the element length and there is a distance between the air guiding elements (13) in a direction perpendicular to the element length, characterized in that the air guiding elements (13) are designed to be elastically deformable, wherein the air guiding elements (13) are arcuate and at least partially elastically prestressed between the first attachment element (11) and the second attachment element (12) and the air guiding elements (13) are completely located between the first attachment element (11) and the second attachment element (12) in this prestressed state.Device (1) according to Claim 1, in which the element length of the air guiding elements (13) is greater than the direct distance between the first attachment element (11) and the second attachment element (12).Device (1) according to one of the preceding claims 1 or 2, in which more than two air guiding elements (13) are provided, wherein the element length of at least two air guiding elements (13) differs from one another.Device (1) according to one of the preceding claims 1 to 3, in which the distance between the air guiding elements (13) extends in a direction perpendicular to their element length in the direction of an extension direction (ER) and more than two air guiding elements (13) are provided, which are arranged next to one another in the extension direction (ER) at respective distances from one another, wherein the element length of the air guiding elements (13) arranged on the outside in the extension direction (ER) is smaller than the element length of air guiding elements (13) arranged between the air guiding elements (13) arranged on the outside in the extension direction (ER).Device (1) according to one of the preceding claims 1 to 4, in which at least one transverse connection is provided, which connects two air guiding elements (13) in a direction perpendicular to their element length, wherein the transverse connection only partially covers the distance or the gap between the air guiding elements (13) in a direction perpendicular to the element length.Device (1) according to one of Claims 1 to 5, in which, when the first attachment element (11) is arranged in the vertical direction above the second attachment element (12), the air guiding elements (13) are arranged completely between the first attachment element (11) and the second attachment element (12) in the vertical direction.Device (1) according to one of Claims 1 to 5, in which the air guiding elements (13) are designed to be elastically deformable, wherein the first attachment element (11) and / or the second attachment element (12) comprise a drawing-in device which is configured to draw in or discharge at least part of the air guiding elements (13) as required, as a result of which the sub-region of the element length of the air guiding elements (13) which is located outside and between the first attachment element (11) and the second attachment element (12) is designed to be adjustable.Vehicle (100) having a device (1) for reducing the air resistance according to one of the preceding claims, wherein the device (1) is arranged at the rear of the vehicle (100) and the first attachment element (11) and the second attachment element (12) are fixed to the vehicle (100), wherein the first attachment element (11) is arranged above the second attachment element (12) in the vertical direction and the distance between the air guiding elements (13) is oriented in a direction perpendicular to the element length in the horizontal direction.Method for changing the air resistance of a vehicle (100) having a device (1) for reducing the air resistance of a vehicle (100), wherein the device (1) is arranged at the rear of the vehicle (100), the device comprising: - at least one first attachment element (11), which can be connected to the vehicle (100), - at least one second attachment element (12), which can be connected to the vehicle (100), - at least two air guiding elements (13), which are designed in the manner of a band and have an element length, which is greater than an element width and an element thickness by at least a factor of 10, wherein a first side of the air guiding elements (13) is connected or connectable to the first attachment element (11) in the direction of the element length and a second side of the air guiding elements (13) opposite the first side is connected or connectable to the second attachment element (12) in the direction of the element length and there is a distance between the air guiding elements (13) in a direction perpendicular to the element length, wherein the air guiding elements (13) are designed to be elastically deformable, wherein the first attachment element (11) and / or the second attachment element (12) comprise a drawing-in device which is configured to draw in or discharge at least a part of the air guiding elements (13) as required, whereby the partial region of the element length of the air guiding elements (13) which is located outside and between the first attachment element (11) and the second attachment element (12) is designed to be adjustable, the method comprising the method steps: A) determining the travel speed of the vehicle (100), B) continuously adapting the partial region of the element length of the air guiding elements (13), which is located outside and between the first attachment element (11) and the second attachment element (12), by the intake device as a function of the determined travel speed of the vehicle (100), wherein this adaptation takes place in steps or continuously to different travel speeds, in particular wherein the partial region of the element length of the air guiding elements (13), which is located outside and between the first attachment element (11) and the second attachment element (12), is enlarged as the travel speed increases.

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