Air guide element for a motor vehicle body

Abstract

Air guide element for a motor vehicle body, wherein the air guide element (3) is arranged on a rear section (2) of the motor vehicle body (1), and wherein the motor vehicle body (1) has a horizontally formed underbody (16) which is formed opposite a driving floor (24), and wherein the air guide element (3) is connected to the underbody (16), and wherein the air guide element (3) is designed to be immovably attached to the rear section (2), characterized in that a step (25) is formed between the air guide element (3) and the underbody (16), wherein the air guide element (3) has a first element part (11) which extends from a rear lower part (5), which extends along a longitudinal axis (X) of the body above the air guide element (3), along a vertical axis (Z) of the body in the direction of the driving floor (24),and wherein the air guide element (3) comprises a second element part (13) adjoining a first lower edge (14) of the first element part (11), and wherein the step (25) is arranged vertically to the subfloor (16), wherein an almost right angle is formed between the element strip (19) and the subfloor (16), and wherein the step (25) is realized by means of an element strip (19) formed on the air guide element (3) or on the subfloor (16), wherein a strip edge (20) of the element strip (19) formed between the element strip (19) and the subfloor (16) is sharp-edged.

Description

The invention relates to an air guide element for a motor vehicle body according to the preamble of claim 1. Air guide elements for motor vehicle bodies are known. These air guide elements are so-called diffusers or rear diffusers, which are mounted on the motor vehicle body to, in particular, generate preferential downforce on the vehicle during operation. The rear diffuser is designed as a component section of the rear of the vehicle body, adjacent to the underbody. German patent application DE 10 2010 008 348 A1 discloses an air guide element for a motor vehicle body, wherein the rear of the motor vehicle body is designed in the form of a hatchback and has a rear diffuser. A trailing edge is provided at an end of the rear diffuser facing away from the motor vehicle body. The trailing edge is designed as the end edge of the rear diffuser in the direction of a longitudinal axis of the motor vehicle. The patent application DE 10 2013 109 652 A1 discloses an air guide element for a motor vehicle body in the form of a diffuser fin, which is arranged on a rear floor lower part of the motor vehicle body. From patent application WO 2007 / 096 553 A2, an air guide element for a motor vehicle body is known, wherein the air guide element is arranged on a rear section of the motor vehicle body. The air guide element is connected to an underbody of the motor vehicle body and is fixed to the rear section. German patent application DE 10 2017 114 863 A1 describes an air guide element for a motor vehicle body, which is arranged in a rear section of the vehicle body. The air guide element is movably connected to an underbody of the vehicle body. The patent application DE 10 2004 022 179 A1 discloses an air guide element for a motor vehicle body in the form of a diffuser formed at the rear with a fixed and a movable part. The object of the present invention is to provide an improved air guide element for a motor vehicle body. The problem is solved according to the invention with an air guide element for a motor vehicle body having the features of claim 1. Advantageous embodiments with expedient and non-trivial further developments of the invention are specified in the respective dependent claims. An air guide element according to the invention for a motor vehicle body is arranged on a rear section of the motor vehicle body. The motor vehicle body has a horizontally designed underbody, which is formed opposite a driving floor. The air guide element is connected to the underbody, wherein the air guide element is designed to be immovable on the rear section.According to the invention, a step is formed between the air guide element and the underbody, wherein the air guide element has a first element part which extends from a rear lower part, which extends along a longitudinal body axis above the air guide element, along a vertical body axis in the direction of the road surface, and wherein the air guide element comprises a second element part adjoining a first lower edge of the first element part, and wherein the step is arranged vertically to the underbody, wherein an almost right angle is formed between the element strip and the underbody, and wherein the step is realized by means of an element strip formed on the air guide element or on the underbody, wherein a strip edge of the element strip formed between the element strip and the underbody is sharp-edged.In other words, the contour formed at the junction of the underbody and the air guide element is not continuous, but has a step at the point of contact. This step has been shown to reduce both drag and rear downforce. The step can be easily achieved using an element strip formed on the air guide element or on the underbody. The element strip is arranged vertically to the subfloor, or in other words, the step is designed perpendicular to the subfloor, which allows for simplified and therefore cost-effective manufacturing due to an undercut-free profile of the air guide element. One edge of the element strip is sharply defined between the element strip and the subfloor, resulting in a forced flow separation. In one embodiment of the air guide element according to the invention, the step is arranged offset from the outermost edge of the air guide element in the direction of a wheel recess of the vehicle body, relative to the longitudinal axis of the vehicle. In other words, the step is located at the point where the airflow enters the air guide element from the underbody, thereby achieving a further reduction of rear downforce. The step is preferably formed between the air guide element and the underbody in the direction of a vehicle body longitudinal axis, wherein the air guide element has a distance to the road surface that is greater than the distance between the underbody and the road surface. In other words, this means that the airflow from the underbody can flow freely over the air guide element. In a further embodiment of the air guide element according to the invention, it is formed in one piece with a rear lower section of the rear segment. This allows for the cost-effective production of a single-piece component, as, for example, no assembly costs are incurred for connecting the air guide element to the rear lower section. A further advantage of the one-piece design is that, since the connection point between the rear lower section and the air guide element is eliminated, the operational reliability of the entire component can be increased, as the air guide element is prevented from detaching from the rear lower section. In a further embodiment, the guide element with the rear lower part is manufactured cost-effectively using a deep drawing process or an injection molding process. If, as proposed in a further embodiment of the air guide element according to the invention, the air guide element and / or the rear lower part are designed in a lightweight construction, in particular made of a fiber composite material, the weight of the vehicle body is significantly reduced. Preferably, the air guide element is designed in the form of a rear spoiler and / or a diffuser, a so-called rear diffuser. The term "diffuser" also includes small diffusers on the underbody of the vehicle body, which serve to cool, in particular, disc brakes. Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and with reference to the drawings. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention. Identical or functionally equivalent elements are assigned identical reference numerals. Figure 1 shows a side view of a section of the rear of a motor vehicle body with an air guide element according to the invention, and Figure 2 shows a perspective view of the rear of the motor vehicle body according to Figure 1. A motor vehicle body 1 has a rear section 2 designed according to Fig. 1. The rear section 2 is designed to include an air guide element 3 according to the invention, which is designed in the form of a rear diffuser. The rear diffuser 3 is fixed to the rear section 2. Due to its shape, the rear diffuser 3 achieves a corresponding pressure distribution on the diffuser surface 4 opposite a road surface 24, which generates downforce from a certain speed of the motor vehicle carrying the motor vehicle body 1. The rear section 2 consists of a lower rear section 5, which is designed to accommodate the air guide element 3, and an upper rear section 6, which is designed to accommodate the lower rear section 5. Preferably, the lower rear section is made of a plastic as an injection-molded component, whereas the upper rear section 6 is made of a metallic material. However, other, even identical, materials could also be used for both rear sections 5 and 6. The rear lower section 5 consists of a first side section 7 and a second side section 8, between which a central section 9 is formed, extending predominantly in the direction of a transverse body axis Y and a vertical body axis Z. The two side sections 8, 9 extend predominantly in the direction of a longitudinal body axis X and the vertical body axis Z. The air guide element 3 is formed in the central section 9 of the rear lower section 5. It extends outwards from a lower surface 10 of the central section 9. In this embodiment, the air guide element 3 has a first element part 11 extending along the transverse body axis Y and in the direction of the vehicle's vertical axis Z, which is arranged almost perpendicular to a trim strip 12 of the rear lower section 5. A second element part 13 is formed adjoining a first lower edge 14 of the first element part 11, the first lower edge 14 being directed away from the trim strip 12. The second element part 13, which also extends along the transverse body axis Y and both in the direction of the vehicle's vertical axis Z and in the direction of the vehicle's longitudinal axis X, is connected at its second lower edge 15, which faces away from the first lower edge 14, to a horizontally extending underbody 16 of the vehicle body 1. The first element part 11 and the second element part 13 are arranged in the direction of the transverse body axis Y between a third element part 17 and a fourth element part 18. The air guide element 3 thus has a rhomboid cross-section divided along its diagonal. Between the underbody 16 and the second lower edge 15, a gap A exists in the direction of the body's vertical axis Z. This gap is bridged by an element strip 19 of the air guide element 3, thus forming a step 25 between the air guide element 3 and the underbody 16 when viewed in the direction of the body's longitudinal axis X. The air guide element 3 has an element distance LA to the road surface 24, which is greater than the underbody distance UA of the underbody 16 to the road surface 24. In other words, the second lower edge 15 of the second element part 13 is positioned higher in the direction of the body's vertical axis Z than the underbody 16. The element strip 19, and therefore also the step 25, are arranged vertically to the subfloor 16. In other words, there is an almost right angle between the element strip 19 and the subfloor 16. Stage 25 leads to a reduction in the air resistance of the vehicle body 1 and a reduction in rear downforce. The element strip 19 has a sharp edge 20 facing the underbody 16, so that flow separation can occur. Furthermore, the step 25 is arranged offset from the outermost air guide element edge 26 of the air guide element 3 in the direction of the vehicle's longitudinal axis X and in the direction of the wheel recess 23. The outermost air guide element edge 26 is the edge of the guide element 3, viewed in the direction of the vehicle's longitudinal axis X and from the wheel recess 23, which has the greatest distance from the wheel recess 23. Or, in other words, it is the edge of the air guide element 3 closest to its surroundings in the direction of the vehicle's longitudinal axis X. In a preferred embodiment, the element parts 11, 13, 17, 18 are manufactured in one piece with the central part 9, the side parts 7, 8, the end strip 12, and a bottom section 21 of the base 16. The bottom section 21 can also be easily connected to the rest of the base 16, for example, by a material bond or a form-fit. Alternatively, the bottom section 21 could be integrated into the base 16, and the base 16 could be connected to the element strip 19. In the central section 9, recesses 22 are formed to the right and left of the air guide element 3, which can accommodate exhaust tailpipes of an internal combustion engine (not shown) of the motor vehicle. The side sections 7, 8 each terminate at a wheel recess 23 of the motor vehicle body on their side facing away from the central section 9. For vehicles without an exhaust system, such as electric vehicles, the recesses 22 can be omitted, and the step 25 can be made wider, thus achieving a greater reduction in the air resistance of the motor vehicle body 1 and a greater reduction in rear downforce. Reference symbol list 1 Vehicle body 2 Rear section 3 Air guide element 4 Diffuser surface 5 Lower rear section 6 Upper rear section 7 First side section 8 Second side section 9 Center section 10 Lower section surface 11 First element section 12 End strip 13 Second element section 14 First lower edge 15 Second lower edge 16 Underbody 17 Third element section 18 Fourth element section 19 Element strip 20 Strip edge 21 Underbody section 22 Recess 23 Wheel recess 24 Road surface 25 Step 26 Outermost air guide element edge A Distance LA Element spacing UA Underbody spacing X Longitudinal axis of the body Y Transverse axis of the body Z Vertical axis of the body

Claims

Air guide element for a motor vehicle body, wherein the air guide element (3) is arranged on a rear section (2) of the motor vehicle body (1), and wherein the motor vehicle body (1) has a horizontally formed underbody (16) which is formed opposite a driving floor (24), and wherein the air guide element (3) is connected to the underbody (16), and wherein the air guide element (3) is designed to be immovably attached to the rear section (2), characterized in that a step (25) is formed between the air guide element (3) and the underbody (16), wherein the air guide element (3) has a first element part (11) which extends from a rear lower part (5), which extends along a longitudinal axis (X) of the body above the air guide element (3), along a vertical axis (Z) of the body in the direction of the driving floor (24),and wherein the air guide element (3) comprises a second element part (13) adjoining a first lower edge (14) of the first element part (11), and wherein the step (25) is arranged vertically to the subfloor (16), wherein an almost right angle is formed between the element strip (19) and the subfloor (16), and wherein the step (25) is realized by means of an element strip (19) formed on the air guide element (3) or on the subfloor (16), wherein a strip edge (20) of the element strip (19) formed between the element strip (19) and the subfloor (16) is sharp-edged. Air guide element according to claim 1, characterized in that the step (25) is arranged offset from the outermost guide element edge (26) in the direction of a motor vehicle longitudinal axis (X) relative to an outermost air guide element edge (26) in the direction of a wheel recess (23) of the motor vehicle body (1). Air guide element according to claim 1 or 2, characterized in that the step (25) is formed between the air guide element (3) and the underbody (16) in the direction of a motor vehicle body longitudinal axis (X), wherein the air guide element (3) has an element distance (LA) to the road surface (24) which is greater than an underbody distance (UA) of the underbody (16) to the road surface (24). Air guide element according to one of the preceding claims, characterized in that the guide element (3) is manufactured in one piece with a rear lower part (5) of the rear section (2). Air guide element according to claim 4, characterized in that the guide element (3) is manufactured with the rear lower part (5) in a deep drawing process or an injection molding process. Air guide element according to one of the preceding claims, characterized in that the air guide element (3) and / or the rear lower part (5) are designed in a lightweight construction, in particular made of a fiber composite material. Air guide element according to one of the preceding claims, characterized in that the air guide element (3) is designed in the form of a rear diffuser.

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