AIR GUIDE DEVICE FOR GUIDING THE DRIVE WIND ALONG A TRAILER TOWED BY A MOTOR VEHICLE

Abstract

The invention relates to an air guidance device for guiding the airflow along a trailer towed by a motor vehicle, comprising at least the following components: - at least one elastic tensioning element; and - at least one flat air guide element, which is attached to at least one clamping element, wherein the clamping element has a first fastening element for attachment to a motor vehicle and a second fastening element for attachment to a trailer towed by the motor vehicle, wherein, in the fastened state, a longitudinal direction is formed between the fastening elements by the clamping element and the clamping element is tensioned in the longitudinal direction. Here is a proposed air guide device for a vehicle combination that is easy to retrofit, simple to install and stow away, and effectively reduces the braking effect caused by wind.

Description

[0001] The invention relates to an air guiding device for guiding the airstream along a trailer pulled by a motor vehicle, as well as a trailer combination with such an air guiding device.

[0002] When driving a combination of vehicles, for example, a passenger car (car) as the towing vehicle with a trailer attached or coupled to it, turbulence forms between the car and the trailer, negatively affecting the drag coefficient. This causes high fuel consumption. Furthermore, the wind can impair the dynamic stability of the vehicle combination.

[0003] Various approaches are known from the prior art to reduce the drag coefficient when driving a car-trailer combination. For example, DE 32 17 970 A1 discloses a wind deflector tarpaulin stretched in the manner of a truncated pyramid. The edge defining the small base area (of the truncated pyramid) of the tarpaulin can be attached to a caravan's drawbar, and the edge defining the large base area (of the truncated pyramid) can be attached to the front of the caravan at its roof base. Starting at the front, the tarpaulin extends diagonally from both side walls to approximately the floor of the caravan.

[0004] US 3,794,372 A describes a device for reducing air resistance in a caravan. The device comprises a spoiler-like wind deflector mounted on the roof of a towing vehicle, which directs airflow over the caravan. US 2020 / 0 406 990 A1 discloses a spoiler for the loading area of ​​a pickup truck. The spoiler serves to deflect airflow over a caravan pulled by the pickup truck.

[0005] The devices described above are complex to install and impractical in cars, and are inflexible in handling when changing trailers.

[0006] Furthermore, wind deflectors are known that are mounted on the cabs of trucks and are designed as superstructures that protrude from the cab. These direct the wind over the trailer, thus reducing air resistance. Such superstructures are unsuitable and impractical for use on cars. Permanently mounted windshields, which cannot be removed without considerable effort, also negatively impact the handling of the car when traveling without a trailer.

[0007] Furthermore, the solutions known from the state of the art are generally not retrofittable and conflict with the maximum utilization of the maximum permissible mass of a trailer or the entire vehicle combination.

[0008] Based on this, the present invention is based on the object of at least partially overcoming the disadvantages known from the prior art. The features of the invention are derived from the independent claims, for which advantageous embodiments are presented in the dependent claims. The features of the claims can be combined in any technically reasonable manner, whereby the explanations from the following description as well as features from the figures, which comprise additional embodiments of the invention, can also be consulted for this purpose.

[0009] The invention relates to an air guiding device for guiding the airstream along a trailer pulled by a motor vehicle, comprising at least the following components: - at least one elastic tensioning element; and - at least one flat air guide element which is attached to the at least one clamping element, wherein the tensioning element has a first fastening element for fastening to a motor vehicle and a second fastening element for fastening to a trailer pulled by the motor vehicle, wherein in the fastened state, a longitudinal direction is formed by the tensioning element between the fastening elements and the tensioning element is tensioned in the longitudinal direction.

[0010] Unless explicitly stated otherwise, ordinal numbers used in the preceding and following descriptions serve only to clearly distinguish them and do not reflect the order or ranking of the designated components. An ordinal number greater than one does not necessarily imply that another such component must be present.

[0011] In one embodiment, a trailer is a cargo trailer whose load area is covered with a tarpaulin, or a camping trailer or caravan.

[0012] The longitudinal direction of the tensioning element is defined by the shortest (imaginary) connection between the fastening elements and / or runs parallel to the longest extension of the tensioning element. For example, in a rope-shaped design of the tensioning element, the longitudinal direction runs along the rope. In a motor vehicle, the longitudinal axis aligned in the occupant's line of sight (e.g. from a driver's seat back over a steering wheel out through a windshield) is usually referred to as the x-axis, the transverse axis aligned in the plane of the occupant's line of sight and perpendicular to the longitudinal axis is referred to as the y-axis, and the vertical axis perpendicular to the two aforementioned axes is referred to as the z-axis (with a positive direction opposite to the orientation of the Earth's gravitational field) of a Cartesian coordinate system. In one embodiment, the longitudinal direction is parallel to the (straight-ahead) direction of travel of the trailer or slightly inclined to it in a plan view.Thus, according to the previous definition, the longitudinal direction has a significantly larger x-component than the y-component, or the y-component is zero. Preferably, the z-component is also (sometimes significantly) smaller than the x-component, but is generally greater than zero.

[0013] The respective tensioning element preferably has an elasticity that enables tensioning between a motor vehicle (e.g., a passenger car), preferably in a central or rear region, particularly preferably on a roof rack, and a front region of the trailer (relative to the straight-ahead direction of travel), preferably at an existing tie-down point, particularly preferably a keder rail. The front region of the trailer is, for example, a front region exposed to the airflow while the trailer is traveling, or an upper edge of this front region.The respective tensioning element has a tension which prevents sagging of the tensioning element with (all) attached air guide elements or keeps it so low that a maximum deviation from an ideal straight line between the fastening elements of the sagging tensioning element is less than 10% [ten percent], preferably less than 5%, of the extension of the tensioning element between the fastening elements in the longitudinal direction. Preferably, a lowest point of the tensioning element (in the z-direction) is not lower than the first fastening element. At the same time, the elasticity (or softness) is so great that cornering of the vehicle / trailer combination, in which an angle in the xy plane, i.e. around a z-axis, exists between the towing vehicle and the towed trailer, is not noticeably impaired.Preferably, the resulting force opposing cornering is less than a force resulting from a wind load on the trailer when the air guidance device is not installed. Alternatively or additionally, the resulting force opposing cornering is less than a force resulting from the frictional forces of a towing hitch, which also opposes cornering.

[0014] In one embodiment, the respective tensioning element, in an untensioned (i.e., for example, unassembled) state, has a length between 30 cm [thirty centimeters] and 200 cm, preferably 50 cm and 100 cm. The dimensions depend on the intended use and / or the permissible elasticity. In one embodiment, the length (of at least a section) of the tensioning element, and thus a desired elasticity or desired force, is adjustable. For example, such adjustability can be adjusted or controlled by a user via the amount of deflection.

[0015] The respective air guide element is made of a rigid or (preferably) flexible material. A flexible material can be bent, folded and / or rolled up when handled or assembled by a user by hand, i.e. without the use of tools. A fabric material is preferably used for this purpose. This enables space-saving storage of the air guide elements. A rigid material cannot be bent, folded and / or rolled up by a user or only only without damage. A (preferably fiber-reinforced) plastic is preferably used for this purpose, preferably a thermoplastic. An air guide element made of a rigid material has, for example, an aerodynamic shape, which supports low-resistance air guidance when the vehicle trailer is moving. Preferably, an air guide profile forms which ensures self-stabilization of the air guide element itself.In one embodiment, the air guide element comprises regions of flexible material and regions of (exclusively or inserted) rigid material, preferably alternating in the longitudinal direction. Thus, the air guide element as a whole is foldable and / or rollable.

[0016] The respective fastening element is designed, for example, for mechanically fastening the respective tensioning element to the motor vehicle or to the trailer. Preferably, the first fastening element is designed for fastening to a roof rack (also referred to in various forms as a roof rail or, for short, generally as a roof rack) and / or to a roof rack attachment of the motor vehicle. The second fastening element is preferably designed for fastening to a wall eyelet of the trailer.

[0017] In one embodiment, a single tensioning element is provided, for example for central arrangement (in the y-direction), preferably as a band with a flat extension along the transverse axis at least in the region of the at least one fastened air guide element. In a preferred embodiment, a single band-shaped tensioning element is provided, which preferably has two of the fastening elements at each of its ends (in the longitudinal direction). In one embodiment, the band is reinforced by means of rigid air guide elements. Alternatively, a plurality of tensioning elements are provided, of which the tensioning elements outermost along the transverse axis preferably form the outermost edges of the at least one air guide element or are overlapping or congruent with it. The at least one air guide element is preferably pretensioned along the transverse axis by means of the (outermost) tensioning elements.Alternatively or additionally, an air guide element is stabilized by its design or material and / or by an airflow along the transverse axis and / or prevented from excessive sagging in this direction. A permissible deviation from an ideal straight line between the outer end points (or end edges) of the air guide element in question is, for example, less than 10% [ten percent], preferably less than 5%, of the extension of the tensioning element (in the y-direction).

[0018] It is further proposed in an advantageous embodiment of the air guiding device that at least one, preferably all, of the clamping elements has a first section and a second section in the longitudinal direction of the clamping element, preferably directly adjoining it, wherein the first section has a higher elasticity in the longitudinal direction compared to the second section, wherein preferably the at least one air guide element is attached to the second section.

[0019] By providing sections with different elasticities, the two sections of the tensioning element stretch to different extents under load, in particular during cornering. Preferably, the at least one air guide element is fastened in the second section with the lower elasticity (i.e., higher rigidity compared to the second section), so that any relative displacement of the air guide element to the trailer or to the motor vehicle and / or of the plurality of air guide elements to one another is thereby minimal. The stretching of at least one of the tensioning elements during operation (resulting, for example, from cornering) occurs mainly in the first section due to the higher elasticity (lower rigidity).

[0020] The ratio of the elasticities is, for example, 2:1 [two to one of the elasticity of the first section to that of the second section], 3:1, or even greater, for example, a maximum of 10:1. In one embodiment, the first section is not stretchable or only negligibly stretchable with respect to the design forces, wherein the maximum resistance force (at maximum stretch of the respective tensioning element) is defined solely (or, in a first approximation, exclusively) by the second section.

[0021] It is further proposed in an advantageous embodiment of the air guiding device that the first section is arranged directly adjacent to the first fastening element.

[0022] In one embodiment, the at least one tensioning element is formed from a vehicle-side section and a trailer-side section, with the at least one air guide element being arranged between these two sections. For multiple air guide elements, for example, an intermediate section of the respective tensioning element is provided for each additional air guide element. Alternatively, the tensioning element is formed continuously between the fastening elements. The at least one air guide element is arranged on (for example, relative to the Earth's gravitational field on) the at least one tensioning element, preferably on its second section.

[0023] In one embodiment, the tensioning element in the first section is made of a different material than the one in the second section. In one embodiment, the two sections (or the two different elasticities) are created by changing the properties of the tensioning element. For example, by changing the cross-section, the number of stiffening elements (e.g., fibers), and / or by adding a further stiffening, preferably detachably mountable, component. In a preferred embodiment, the first section and the second section of the tensioning element are directly connected to one another. In one embodiment, the two sections are riveted, woven, and / or glued together. Alternatively, the two sections are detachably connected to one another, for example, by hooking, velcroing, and / or clicking.If the two sections are detachably connectable, two redundant connecting elements are preferably provided. The same applies if the at least one clamping element and the at least one air guide element are detachably connected, preferably at least in the longitudinal direction.

[0024] It is further proposed in an advantageous embodiment of the air guiding device that the at least one air guiding element is fixedly attached to the respective clamping element in the longitudinal direction, preferably by means of at least one of the following means: - Velcro fastener; - Zipper; and - Seam.

[0025] When attached with a hook-and-loop fastener or zipper, the wind deflector can be easily adjusted to the respective distance between the vehicle and caravan. This means that the number of air guide elements and their respective spacing can be adapted to the specific conditions of the vehicle and trailer. The air guide device can be used in a modular manner, and the number and spacing of the air guide elements can be optimized when using a different vehicle or trailer.

[0026] In one embodiment, for example, with a hook-and-loop fastener or zipper, the air guide element in question can be positioned anywhere on the tensioning element or the designated section (at least, preferably exclusively, in the longitudinal direction). For example, the air guide element in question can be adjusted to an individual distance between the towing vehicle and the towed trailer of the vehicle combination. In one embodiment, the number of air guide elements can be flexibly selected depending on such an individual distance of the vehicle combination.

[0027] A hook-and-loop fastener is cost-effective and has minimal impact on the stiffness of a material. Furthermore, the relative arrangement (at least in the longitudinal direction) to at least one tensioning element can be easily adjusted to provide maximum flexibility.

[0028] Using a zipper, an air guide element can be easily and safely mounted correctly, while at the same time being maintenance-free (even when stowed away).

[0029] In one embodiment, the at least one air guide element is folded around the tensioning element in the manner of a pocket-forming seam and / or (especially in the longitudinal direction) is fixed in an overlapping overseam. In one embodiment, the air guide element is not detachable from the at least one tensioning element, but is held displaceably in the longitudinal direction. It can be fixed in any desired position or in one of several positions by means of a further element (e.g., a clamp) or a bolt (e.g., with a perforated tensioning element and at least one corresponding eyelet in the air guide element).

[0030] It is further proposed in an advantageous embodiment of the air guiding device that the respective tensioning element is designed as a tensioning cable, wherein preferably exactly two tensioning elements designed as tensioning cables are provided.

[0031] A tensioning cable allows for easy fastening of the air guide elements while requiring minimal space, both in the assembled and stowed state. The first fastening element and the second fastening element are preferably arranged at opposite ends of the respective tensioning cable.

[0032] In one embodiment, exactly two tensioning cables are provided, each of which preferably forms the outer edge (relative to the transverse axis) of the air guiding device. This is particularly preferably combined with a flexible material of at least one of the air guiding elements. In the case of an air guiding element that is rigid along the transverse axis, a projection is preferably formed along the transverse axis beyond the tensioning cables.

[0033] It is further proposed in an advantageous embodiment of the air guiding device that the air guiding device has a plurality of air guiding elements, preferably trapezoidal in the plane of the guided airstream, and a plurality of tensioning cables.

[0034] In some applications, a towing motor vehicle or a distance along the transverse axis between its suitable attachment points is narrower than the towed trailer or a distance along the transverse axis between its suitable attachment points. This results in a trapezoidal shape with the attachment elements as corners. In an advantageous embodiment, the at least one air guide element is also trapezoidal. In one embodiment, the air guide element is smaller, preferably shorter exclusively in the longitudinal direction, than the trapezoid spanned by the attachment elements. In an embodiment with a plurality of air guide elements, each of the air guide elements is preferably trapezoidal, each being shorter but preferably having the corresponding width (along the transverse axis).

[0035] It should be noted that such suitable attachment points on the motor vehicle and / or on the trailer are sufficiently standardized so that a fixed size of the trapezoid is at least suitable in a variety of ways. Alternatively or additionally, the attachment points and / or the shape and / or the width (along the transverse axis) of the at least one air guide element can be adjusted. For example, the at least one (towing vehicle-side and / or trailer-side) attachment element comprises an intermediate element with a sufficient transverse extension so that a given variance in the position of the suitable attachment points can be compensated for. For example, a respective air guide element is folded over the at least one tensioning element and the fold-over length (i.e., for example, the resulting overlapping doubling) is adjustable, for example by means of a tensioning device and / or a Velcro fastener.

[0036] It is further proposed in an advantageous embodiment of the air guiding device that a plurality of air guiding elements are provided which are fixed to the at least one clamping element at a distance from one another in the longitudinal direction.

[0037] In one embodiment, several air guide elements are provided, which are preferably arranged one behind the other in the longitudinal direction, spaced apart from one another in the manner of ladder rungs, particularly preferably spaced such that they either touch one another or just do not touch one another during design cornering. Design cornering is, for example, one that allows stable travel of the vehicle combination outside of shunting operations above a predetermined travel speed. For example, an angle between the longitudinal axis of the towing vehicle and the longitudinal axis of the towed trailer is less than 30° [thirty degrees of 360°], preferably equal to or less than 15°. Alternatively, a design angle is up to 90°.

[0038] In one embodiment, the majority of the air guide elements are arranged on the stiffer (first) section and are not moved (or at most negligibly) relative to one another during expansion and compression of the tensioning element along the tensioning element. Nevertheless, in one embodiment, such expansion of the tensioning element occurs that it tightens from a (slightly) sagging position to an (at least approximately) straight extension, and conversely, sags (further) from a (relatively) taut extension upon compression. In this case, even with an (approximately ideally) stiff tensioning element or relevant (for example, first) section of the tensioning element, a change in the distance between the air guide elements occurs in the longitudinal direction.Alternatively, this can be prevented by means of a suitable transverse stiffness of the air guide elements, for example the transverse stiffness created by means of at least one sail batten per air guide element.

[0039] A further advantage is that by means of the spacing of the air guiding elements and the openings formed thereby between the surfaces of the air guiding elements, a bulging sagging caused by the incoming flow and / or by gravity is prevented as a result of an incoming flow, but also, on the contrary, a negative pressure which lifts the air guiding device upwards and is generated aerodynamically is prevented.

[0040] It is further proposed in an advantageous embodiment of the air guiding device that at least one, preferably all, of the air guiding elements is formed from a flat material, preferably from a cloth.

[0041] Flat goods are materials that are provided for processing as flat pieces (e.g., rectangles) or rolled up. The materials can be natural, such as leather, or synthetic, such as rolled plastic, or fiber-based materials, such as woven fabrics, scrims, and / or nonwovens. Fiber-based materials are preferably knitted to make them weatherproof or reinforced with a plastic, for example, as fiber composites.

[0042] In an advantageous embodiment, the air guide element is made of a cloth, for example as suitable (or previously used) for a canvas or a tarpaulin of a truck.

[0043] It is further proposed in an advantageous embodiment of the air guiding device that at least one of the fastening elements is designed for magnetic fastening.

[0044] Here, it is proposed that at least one, preferably all, of the fastening elements are designed for magnetic fastening. In an advantageous embodiment, the fastening element in question comprises a permanent magnetic material for this purpose. In one embodiment, the permanent magnetic material has such a high field strength that the fastening element is fixed to the towing motor vehicle or the towed trailer using this material alone (i.e. with such a magnetic force) that the tensioning element cannot come loose during travel at high speeds and when cornering, i.e. reliable fastening is possible using magnetism alone when used as designed. In one embodiment, only a supporting effect is achieved, for example, a positive and / or non-positive connection is supported.

[0045] It should be noted that in one embodiment, the fastening element designed for magnetic fastening does not comprise any magnetic material, but for example comprises exclusively a magnetizable, preferably ferromagnetic, material, wherein the fastening point on the towing motor vehicle or the towed trailer exerts a magnetic field strength by means of which the fastening element in question can be magnetically fastened.

[0046] According to a further aspect, a combination is proposed, comprising a motor vehicle and a trailer pulled by the motor vehicle, wherein an air guiding device according to an embodiment according to the above description is fastened to the motor vehicle with the at least one first fastening element and to the trailer with the at least one second fastening element.

[0047] The towed trailer is preferably of an enclosed design, for example, a box trailer enclosed with tarpaulins, or a caravan or camping trailer. The towing vehicle is preferably a passenger car and / or a flat-bottomed vehicle, such as a sedan. Alternatively, the vehicle is a van, such as a six-seater or larger vehicle, and / or a transport vehicle. The vehicle is preferably designed with a closed roof.The combination preferably has a towed trailer which has an impact surface (cross-sectional surface with the direction of travel as normal) which projects beyond the maximum height of the towing motor vehicle (in the positive z-direction), so that the airflow is guided over the trailer, detaching from the motor vehicle, with the aid of the air guiding device mounted between the towing motor vehicle and the towed trailer, with a small deflection angle, preferably along a flow line which approximates the shortest connecting straight line.

[0048] In an advantageous embodiment, the towing motor vehicle has a roof rack and / or a roof rack attachment, wherein the respective tensioning element is attached to the roof rack or to the roof rack attachment by means of the first attachment element.

[0049] In an advantageous embodiment, the towed trailer has a piping rail and / or eyelet in a front area, for example on its front side, which is first hit by the wind, wherein the respective tensioning element is fastened thereto by means of the second fastening element.

[0050] The proposed air guide device can be retrofitted to common combinations of motor vehicles, such as cars, and trailers, and significantly reduces fuel consumption on highway journeys. Without the trailer, the air guide device can be quickly detached from the motor vehicle (towing the vehicle) without causing any disruption. If the combination of motor vehicle and trailer changes, the air guide device can continue to be used due to its high degree of flexibility and adaptability, meaning there is no need to purchase a new, specific product. The air guide device is cost-effective, easy to install between a motor vehicle and a trailer, easy to remove (or re-remove), and preferably easily folded for storage.For example, the air guidance device can be carried (permanently) in a trunk to save space and can therefore be quickly retrieved and installed when needed.

[0051] Due to the redirection of the airflow along the trailer, the proposed combination has a reduced fuel consumption compared to a comparable combination without an air guidance device.

[0052] The invention described above is explained in detail below against the relevant technical background with reference to the accompanying drawings, which show preferred embodiments. The invention is in no way limited by the purely schematic drawings, whereby it should be noted that the drawings are not to scale and are not suitable for defining proportions. It is shown in Fig. 1: a side view of a trailer with air guidance device; Fig. 2: a trailer with air guidance device in a top view while driving straight ahead; and Fig. 3: the team according to Fig. 2 when cornering.

[0053] In Fig. 1 shows an exemplary trailer 14 with an air guidance device 1 in a side view. This represents a Cartesian coordinate system with a vertical axis 17 (positively defined opposite to the direction of the Earth's gravitational field according to the z-axis commonly used in the automotive sector, pointing vertically upwards in the illustration), a longitudinal axis 16 (in the travel plane, horizontal in the illustration, pointing to the left according to the x-axis commonly used in the automotive sector), and a transverse axis 15 (in the travel plane, pointing into the page plane in the illustration, positively defined according to the y-axis commonly used in the automotive sector). Here, a passenger car in a limousine-like configuration is shown as the towing motor vehicle 3. The trailer 4, attached to a trailer hitch of the motor vehicle 3 and thus towed by the motor vehicle 3, is designed here as a caravan, for example. The trailer 14 is shown in the (pulling) direction of travel 18 while (straight ahead) driving.Shown schematically are representative streamlines of the developing airstream 2. Dashed lines show the course of the streamlines that occurs when no air guiding device 1 is provided. Here it can be seen that turbulence arises, mostly laminar, which causes a high drag force, i.e., results in a high flow resistance coefficient and thus considerable fuel consumption. Solid lines show the course of the streamlines that occurs when the air guiding device 1 proposed here is provided. Here it can be seen that gentle streamlines develop, i.e., those deflected with few and small deflection angles, and here too they are mostly laminar (here with a positive air particle entraining effect), which therefore causes a significantly reduced drag force.By means of the airflow device 1, the airflow 2 is directed from the motor vehicle 3 over the trailer 4 without congestion or turbulence (with macroscopic effects), so that the driving resistance resulting from the airflow 2 is significantly reduced compared to the conventional streamline (shown in dashed lines). The drag coefficient is thus significantly reduced, and thus fuel consumption is significantly reduced.

[0054] The air guiding device 1 has at least one tensioning element 5. The at least one tensioning element 5 is fixed by means of its first fastening element 7 (purely optionally) to a (conventional) roof rack 19 of the motor vehicle 3. By means of its second fastening element 8, the at least one tensioning element 5 is fixed to the trailer 4, preferably to a retaining bracket, an eyelet, or a piping rail. A longitudinal direction 9 is formed by the at least one tensioning element 5. In this embodiment, the streamlines are aligned approximately parallel to the longitudinal direction 9 (relative to the plane spanned by the vertical axis 17 and longitudinal axis 16, i.e., here the plane of the sheet).

[0055] Three separate air guide elements 6 are attached to the at least one tensioning element 5, arranged one behind the other in the longitudinal direction 9 and spaced apart from one another. The air guide elements 6 are fixed in the longitudinal direction 9, for example, i.e., immovably (e.g., by means of a zipper, Velcro fastener, or seam). By spacing the air guide elements 6 and the resulting openings between the surfaces of the air guide elements 6, aerodynamically preventing bulging caused by the incoming air flow and / or gravity, as well as, conversely, a negative pressure aerodynamically generated that lifts the air guide device 1 upwards, is prevented. Furthermore, the individual air guide elements 6 do not cause excessive wrinkling and / or sagging during maneuvering of the trailer 14.In a preferred embodiment, the air guide elements 6 are designed to be flexible, i.e., collapsible or foldable. For this purpose, they are made of fabric, for example.

[0056] In Fig. 2 is an exemplary combination 14, for example as in Fig. 1, with air guiding device 1 in a plan view when driving straight ahead. Without excluding the general public, purely for the sake of clarity, with regard to the details not dealt with here, reference is made to the description of the combination 14 according to Fig. 1. The vertical axis 17 of the Cartesian coordinate system shown points out of the plane of the page, and the longitudinal axis 16 and transverse axis 15 lie in the plane of the page. It should be noted that at least with a similar height ratio as in Fig. 1, the longitudinal direction 9 has a z-component, namely enough to bridge the height difference between the roof of the motor vehicle 3 and the roof of the trailer 4. Furthermore, as can be seen from the illustration, a y-component is included, meaning that here, too, there is no parallelism between the longitudinal axis 16 and the longitudinal direction 9. The latter is advantageous, but not mandatory.

[0057] The air guiding device 1 here has exactly two (outer) tensioning elements 5, which in this case are both designed, for example, as a left tensioning cable 12 and a right tensioning cable 13, respectively. The respective tensioning cable 12, 13 is fastened to the roof (preferably the roof rack 19) of the motor vehicle 3 by means of its first fastening element 7. The respective tensioning cable 12, 13 is fastened to the trailer 4 (preferably to a retaining bracket) by means of its second fastening element 8.

[0058] Independently of this, here (purely optional) the air guide elements 6 in the illustrated (preferred) embodiment are spanned in the plane by the longitudinal direction 9 (compare above and / or Fig. 1) and the transverse axis 15 are trapezoidal in shape, with the larger base side (i.e., the base according to mathematical definition) facing the trailer 4. In this way, the often different widths, and the resulting width ratio, of the towing motor vehicle 3 (or its suitable attachment points) and the towed trailer 4 (or its suitable attachment points) of the vehicle combination 14 are taken into account. This allows the air guide elements 6 to be tensioned in a well-adjusted manner. In one embodiment, a variance in the width ratio can be compensated for by means of elastic deformability of the fabric used in the direction of the transverse axis 15. As a result, the air guide elements 6, made of a flexible material, can be easily tensioned to a sufficient degree, thus achieving good air guidance for the smallest possible flow resistance coefficient.By means of the trapezoidal design of the air guide elements 6 (in their joint arrangement), the guided air is fanned out against the direction of travel 18, thus mitigating any increase in pressure toward the trailer 4, preferably to such an extent that a pressure difference is created with respect to the area below the air guide device 1, which promotes the formation of a static air pocket between the motor vehicle 3 and the trailer 4. This also reduces the constriction effect of the air flowing along the side of the vehicle. The flow resistance coefficient is thus further reduced.

[0059] In Fig. 3 is the team 14 according to Fig. 2 during a (right-hand) curve. For details not described here, please refer to the previous description of Fig. 2 and here only the processes during cornering are discussed.

[0060] The respective tensioning cable 12, 13 has a first section 10 (shown here in dashed lines), which is arranged adjacent to (for example directly adjacent to) the first fastening element 7, and a second section 11 adjoining it in the longitudinal direction 9, which is arranged adjacent to the second fastening element 8. The two sections 10, 11 differ in their elasticity. In the (purely optional) embodiment shown here, the first section 10 has a higher elasticity than the second section 11 (at least in the longitudinal direction 9), i.e. it is softer and more easily reversibly stretchable. Due to the differently elastic sections 10, 11, the air guide elements 6 are not or only slightly displaced relative to one another and / or compressed (inside) during the cornering shown here.The necessary stretching occurs (almost) exclusively in the first section 10. Different elongation requirements arise on the two (outer) tensioning cables 12, 13 due to the direction of the curve (in this case, a right-hand bend). It should be noted that with this design or arrangement of the fastening elements 7, 8, compression occurs in the tensioning cable 13 on the inside of the curve (here, above or right). Therefore, the tensioning cable 12, 13 (or at least the first section 10) is preferably stretched when driving straight ahead compared to an unassembled or unloaded state. The different resulting elastic stretches (or compressions from the normal position stretched when driving straight ahead) of the two (outer) tensioning cables 12, 13 in comparison to one another are each absorbed in their softer first section 10.The air guide elements 6 themselves and their distance from each other are changed only slightly, due to the change in the distance between the (outer) tensioning cables 12,13.

[0061] The air guiding device 1 for a combination 14 comprising a towing motor vehicle 3 and a towed trailer 4 is easy to retrofit and compactly stowable. In an embodiment with air guiding elements 6 that are detachable from the at least one tensioning element 5 (but preferably fixed in place in the assembled state), the air guiding device 1 can be used for different width and height ratios of the motor vehicle 3 and the trailer 4, for example, by adjusting their spacing and / or their number.

[0062] This proposal proposes an easily retrofittable, simple to install and store air guidance device for a trailer, which effectively reduces the braking effect caused by wind. List of reference symbols 1 air guidance device 2 Wind 3 Motor vehicle 4 trailers 5 clamping element 6 Air guide element 7 first fastening element 8 second fastening element 9 Longitudinal direction 10 first section 11 second section 12 left tensioning cable 13 right tensioning cable 14 team 15 Transverse axis 16 Longitudinal axis 17 Vertical axis 18 Direction of travel 19 roof racks QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 32 17 970 A1

[0003] US 3,794,372 A

[0004] US 2020 / 0 406 990 A1

[0004]

Claims

[1] Air guiding device (1) for guiding the airstream (2) along a trailer (4) pulled by a motor vehicle (3), comprising at least the following components: - at least one elastic tensioning element (5); and - at least one flat air guide element (6) which is fastened to the at least one clamping element (5), wherein the tensioning element (5) has a first fastening element (7) for fastening to a motor vehicle (3) and a second fastening element (8) for fastening to a trailer (4) pulled by the motor vehicle (3), wherein in the fastened state of the tensioning element (5) a longitudinal direction (9) is formed between the fastening elements (7, 8) and the tensioning element (5) is tensioned in the longitudinal direction (9). [2] Air guiding device (1) according to claim 1, wherein at least one, preferably all, of the clamping elements (5) has a first section (10) and a second section (11) in the longitudinal direction (9) of the clamping element (5), preferably directly adjoining it, wherein the first section (10) has a higher elasticity in the longitudinal direction (9) compared to the second section (11), wherein preferably the at least one air guide element (6) is fastened to the second section (11). [3] Air guiding device (1) according to claim 2, wherein the first section (10) is arranged immediately adjacent to the first fastening element (7). [4] Air guiding device (1) according to one of the preceding claims, wherein the at least one air guiding element (6) is fixedly attached to the respective clamping element (5) in the longitudinal direction (9), preferably by means of at least one of the following means: - Velcro fastener; - Zipper; and - Seam. [5] Air guiding device (1) according to one of the preceding claims, wherein the respective tensioning element (5) is designed as a tensioning cable (12, 13), wherein preferably exactly two tensioning elements (5) designed as tensioning cables (12, 13) are provided. [6] Air guiding device (1) according to one of the preceding claims, comprising a plurality of air guiding elements (6), preferably trapezoidal in the plane of the guided airstream (2), and a plurality of tensioning cables (12, 13). [7] Air guiding device (1) according to one of the preceding claims, wherein a plurality of air guiding elements (6) are provided, which are fixed to the at least one clamping element (5) at a distance from one another in the longitudinal direction (9). [8] Air guiding device (1) according to one of the preceding claims, wherein at least one, preferably all, of the air guiding elements (6) is formed from a flat material, preferably from a cloth. [9] Air guiding device (1) according to one of the preceding claims, wherein at least one of the fastening elements (7, 8) is designed for magnetic fastening. [10] Team (14), comprising a motor vehicle (3) and a trailer (4) pulled by the motor vehicle (3), wherein an air guiding device (1) according to one of the preceding claims is fastened to the motor vehicle (3) with the at least one first fastening element (7) and to the trailer (4) with the at least one second fastening element (8).

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