Subframe for a motor vehicle, spacer element and motor vehicle

Abstract

A subframe for a motor vehicle, comprising an upper and a lower portion, and with at least one spacer element arranged between the upper and lower portions, wherein the spacer element has a prismatic base body, is characterized in that the spacer element has a planar extension which is connected to a contact surface of the subframe by at least one weld. A spacer element for a subframe of a motor vehicle, comprising a cylindrical base body, is characterized by a stiffening extension for connecting to another element of the subframe, wherein the stiffening extension projects from the base body.

Description

[0001] The invention relates to a subframe for a motor vehicle, comprising an upper portion and a lower portion, and at least one spacer element arranged between the upper portion and the lower portion, wherein the spacer element has a prismatic base body. The invention further relates to a spacer element for a subframe of a motor vehicle, comprising a cylindrical base body, and to a motor vehicle.

[0002] A subframe is a common component in automotive engineering. The body-side pivot points of the wheel suspension are attached to the subframe, and the assemblies, i.e. the engine, transmission and steering gear, are usually also attached to the front subframe. The subframe can also be referred to as a chassis subframe or axle carrier. The subframe often consists of several components that are joined together during production of the subframe. Such components can, for example, be an upper shell and lower shell, which, in simple terms, each form an upper half and a lower half of the subframe. When joined together, the result is a complex hollow profile. In most cases, the upper and lower shells are joined together by a material bond, primarily by welding.However, additional connecting elements can penetrate the upper and lower shells to attach add-on components to the subframe or the subframe to the body shell. To prevent possible deformations caused by this, several spacers are often arranged between the upper and lower shells to ensure the specified shape or distance between the top and bottom of the subframe is maintained.

[0003] During driving, the subframe can be subjected to vibrations that may be perceived as disturbing by vehicle occupants. Therefore, designs with the highest possible natural frequencies for the subframe are preferred to avoid acoustic abnormalities or complaints during driving caused by an excessively low natural frequency of the subframe.

[0004] It is known from the state of the art to take measures to create various geometries with high rigidity while simultaneously reducing weight. In addition to purely geometrical changes, it is also known to provide additional components that are bolted or welded to increase rigidity. These can be struts or similar components, for example.

[0005] EP 3 369 645 B1 discloses a subframe for a motor vehicle, comprising spaced-apart longitudinal members, at least one cross member connecting the longitudinal members, and reinforcing elements connected to the longitudinal members and the cross member and made of sheet metal. The reinforcing elements are composed of a first reinforcing element and a second reinforcing element, which are designed as bent shells and have overlapping ends. The overlapping ends are integrally connected, preferably welded, to the cross member or one of the longitudinal members.

[0006] The solutions known from the state of the art are each characterized by a quite significant additional weight and / or increased costs compared to a subframe without optimizing the stiffness, so that an improvement in the cost-benefit ratio is desirable.

[0007] The object of the present invention is therefore to provide a subframe which exhibits advantageous vibration behavior and can be manufactured in a structurally simple manner.

[0008] The object is achieved according to the invention by a subframe of the type mentioned at the outset, in which the spacer element has a flat extension which is connected to a contact surface of the subframe by at least one welded joint. The invention is further achieved by a spacer element of the type mentioned at the outset, with a stiffening extension for connecting to another element of the subframe, wherein the stiffening extension protrudes from the base body, and by a motor vehicle with such a subframe or with such a spacer element. The stiffening extension can correspond to the previously described flat extension. The upper part is usually referred to below as the "upper shell", and the lower part is usually referred to below as the "lower shell".

[0009] The inventive design stiffens the subframe with minimal structural effort, which in turn leads to higher natural frequencies of the subframe. The acoustic properties of the subframe are thus improved in a simple manner. The flat extension establishes a physical connection between the spacer element and the contact surface or the structure of which the contact surface is a part. This structure can be part of the upper part of the subframe, the lower part of the subframe, or another part of the subframe. The spacer element is generally oriented vertically. Accordingly, it can be provided that the contact surface is oriented essentially parallel to a central axis of the prismatic base body.By the fact that the contact surface is aligned substantially parallel to the central axis, it is understood in particular that an angle between the contact surface and the central axis is less than 20°, preferably less than 10°. In a specific embodiment, the central axis of the prismatic base body is parallel to the contact surface. The central axis of the prismatic base body can expediently be aligned vertically.

[0010] The term "contact surface" will be used figuratively in the following and should also be understood in such a way that the term "contact surface" can also refer to a component or a section of a component, and not necessarily to a specific surface of that component. In other words, the term "contact surface" can also refer to a component whose surface is the contact surface, or to a section of such a component.

[0011] According to a preferred embodiment, the extension extends in a plane parallel to a central axis of the prismatic base body. It is possible for the extension to extend in a radial or tangential direction relative to a circumference of the prismatic base body. The flat extension can establish a connection between the lateral surface of the prismatic base body and the contact surface.

[0012] A prismatic base body is understood, in particular, to be a body that has a geometric shape with two mutually parallel and at least substantially congruent end faces and at least one lateral surface extending perpendicular to these end faces. The end faces can, for example, have the shape of a regular polygon, such as a square, a hexagon, or an octagon. However, the end faces can also be elliptical, oval, or circular. In this preferred embodiment, the prismatic base body is then a cylindrical base body.

[0013] In a special embodiment, the extension tapers trapezoidally from the prismatic base body. In other words, the contact area between the extension and the contact surface is then smaller than the base body in a direction parallel to the longitudinal axis of the base body. This allows for material and thus weight savings, while at the same time largely preserving the positive effects on vibration behavior.

[0014] According to the features described above, the welded joint can preferably be a substantially vertical weld seam. Alternatively, several spot welds can be provided, or another suitable configuration can be chosen. If the welded joint is a weld seam, it can be a weld seam running parallel to a central axis of the prismatic base body.

[0015] According to one embodiment, it is possible for a portion of the extension to penetrate a slot arranged in the contact surface. The contact surface can be part of a portion of the subframe made of a metal sheet. The slot arranged in the contact surface can preferably be adapted to the cross-section or the size of an end face of the extension. In other words, the shape of the slot can, in principle, correspond to the outline of an end face of the extension, but should be slightly larger so that the extension can be easily inserted into the slot.

[0016] The welded joint can be arranged on a side of the contact surface facing the base body. In particular, if the subframe is designed such that a portion of the extension penetrates a slot arranged in the contact surface, as described above, the welded joint can also be arranged on a side of the contact surface facing away from the base body. Of course, in this case, welded joints can also be arranged on both sides of the contact surface.

[0017] According to a preferred embodiment, the spacer element is designed as a single piece. In particular, the spacer element can be configured as a partially rolled sheet metal. For this purpose, a flat sheet metal can be partially rolled up, so that the rolled portion then corresponds to the cylindrical base body, in this case. The non-rolled portion of the sheet metal then corresponds to the flat extension and is then welded to the contact surface in an end region, for example on an end face. A cross-section of the base body can correspond to a circular arc of at least 180°. Preferably, the cross-section of the base body corresponds to a circular arc with an angle of 270° - 360°, particularly preferably from 300° to 355°.

[0018] A particularly stable construction is achieved when a screw or bolt connecting the upper and lower sections of the subframe runs through the spacer element. The spacer element can absorb axial forces and, together with the screw or bolt, creates a stable connection between the upper and lower sections.

[0019] According to a special embodiment, it is possible for the extension to have an end section that forms an angle of 10° to 60°, preferably 20° to 40°, with a main section of the extension. In other words, the extension can have a change or deformation in an end region, so that the extension has a slight bend 34. The extension can preferably be designed such that there is contact between a portion of a side surface of the extension located in the end region of the extension and the contact surface. In this way, an enlarged contact area between the extension and the contact surface can be achieved, whereby greater stability and correspondingly higher rigidity can be achieved. Depending on the embodiment, the extension can therefore be in contact with the contact surface with an end face or with a portion of a side surface.

[0020] According to an optional development of the invention, the extension has weight-reducing recesses. By cleverly designing the recesses, for example, as elongated holes that can be oriented vertically, significant weight savings can be achieved while simultaneously having only a minimal impact on the rigidity of the component.

[0021] According to a further optional embodiment, the extension can have a bead. The extension can therefore have one or more beads. This further increases rigidity. Similar to weight reduction with the help of recesses, the rigidity-to-weight ratio can also be improved in this way.

[0022] Conveniently, the material thickness of the spacer element in the area of ​​the base body can be between 0.5 mm and 10 mm, preferably between 2 mm and 6 mm, and particularly preferably between 2 mm and 4 mm. In other words, the sheet thickness of a sheet from which the spacer element is made can be between 0.5 mm and 10 mm, preferably between 2 mm and 6 mm, and particularly preferably between 2 mm and 4 mm.

[0023] It is possible to use different material thicknesses, such as sheet metal thicknesses, for different components of the spacer element. For example, the material thickness of the spacer element in the area of ​​the extension can be less than the material thickness of the spacer element in the area of ​​the base body. This way, the different demands on the various parts of the spacer element can be taken into account. The base body often has to absorb large forces in the axial direction, whereas the extension is intended to stiffen the subframe and can therefore usually be made less solid. Weight savings can also be achieved in this way. The opposite case, in which the material thickness of the spacer element in the area of ​​the extension is greater than the material thickness of the spacer element in the area of ​​the base body, is also possible.In this way, the spacer element can also be adapted to the specific requirements of the respective application.

[0024] The stiffening extension of the spacer element according to the invention can preferably be designed as a flat surface, wherein a surface normal of a main surface of the stiffening extension can be at least approximately perpendicular to a central axis of the base body of the spacer element. The base body of the spacer element is preferably designed as a rolled sheet metal section.

[0025] Embodiments of the invention are explained in more detail with reference to the drawings and the following description. They show: Fig. 1: a first embodiment of a subframe according to the invention, Fig. 2: a section of the subframe according to the first embodiment, Fig. 3: a plan view of a portion of the subframe according to the first embodiment, Fig. 4: a further perspective view of the area of ​​the first embodiment having the spacer element, Fig. 5: a section of a side view of a second embodiment, Fig. 6: a schematic plan view of a section of a third embodiment of a subframe according to the invention, Fig. 7: a way to perform the welding connection, Fig. 8: another design option for the spacer element, Fig. 9: a section of a sixth embodiment of a subframe according to the invention in a schematic plan view, Fig. 10: a perspective view of a section of a seventh embodiment of a subframe according to the invention, Fig. 11: another perspective view of the seventh embodiment, Fig. 12: a perspective view of a section of an eighth embodiment of a subframe according to the invention, Fig. 13: a plan view of a ninth embodiment of a subframe according to the invention, and Fig. 14: a perspective view of the ninth embodiment.

[0026] Fig. 1 shows a first exemplary embodiment of a subframe 2 according to the invention. The subframe 2 of the exemplary embodiment shown consists mainly of three basic structural elements which together form the subframe 2. For orientation, the direction of travel F of a vehicle, of which the subframe 2 can be a part, is shown. The basic elements, namely the upper shell 4, the lower shell 6 and the body 8, consist of three-dimensionally pre-formed metal parts. When assembled, the subframe 2 has a plurality of hollow profile-like sections which are designed in such a way that efficient force transmission, in particular from the wheels suspended on the subframe 2, to the remaining components of a motor vehicle can take place. The upper shell 4 and the lower shell 6 of the subframe 2 are connected to one another at several points by screws which can be used to attach further components to the subframe 2 orserve to secure the subframe 2 to the bodyshell. At some points, the screws run vertically through spacers 12, which are designed as relatively simple metal sleeves. However, according to the invention, at least one spacer 10 is designed to deviate from the shape of a simple metal sleeve and will be described in more detail below. The highlighted section of the . Fig. 1 is in Fig. 2 shown enlarged.

[0027] Fig. Figure 2 shows a section of the subframe 2 according to the first exemplary embodiment. The upper shell 4 and the lower shell 6 are again shown. The spacer element 10 is arranged between the upper shell 4 and the lower shell 6. The spacer element 10 has a cylindrical base body 14 and an extension 16. In the exemplary embodiment shown, the extension 16 is formed integrally with the base body 14. Furthermore, the base body 14 has a hollow cylindrical base structure. A spacer piece 18 is formed, for example, welded, onto the upper shell 4 above the base body 14.A screw can pass from below through a hole in the lower shell 6 (not visible in the figure), through the central cavity of the base body 14 and through the spacer 18, thus exerting a force pulling the upper shell 4 and the lower shell 6 together, which force is absorbed by the spacer element 10 in order to prevent deformation of the subframe 2.

[0028] The extension 16 has a substantially flat, planar basic shape. The extension 16 is attached by one edge to another part of the subframe 2. In the illustrated embodiment, this part of the subframe 2 is the contact surface 20. The contact surface 20 is in turn a surface belonging to the body, which in the illustrated embodiment is oriented substantially vertically. The extension 16 can be connected to the contact surface or to the other element of the subframe 2 with a welded joint, for example with a weld seam or with multiple weld points.

[0029] Fig. Figure 3 shows a plan view of a portion of the subframe according to the first exemplary embodiment. It shows the lower shell 6, the body 8, and the spacer element 12. It can be seen that the spacer element 12 is made of a formed sheet metal. One section of the sheet metal forms the base body 14, and another section forms the extension 16. In the exemplary embodiment shown, the spacer element 12 was manufactured from an originally flat sheet metal that was partially rolled up, resulting in the base body 14 from the rolled sheet metal section. In the exemplary embodiment shown, a free space 26 in the form of a gap remains between an edge terminating the base body 14 and a flat section of the spacer element 12. In the exemplary embodiment shown, the flat section corresponds to the extension 16.

[0030] The extension 16 rests with its end opposite the base body 14 against the contact surface 20 of the body 8. Furthermore, the extension 16 is secured to the contact surface 20 or to the body 8 by the welded connection 22. The welded connection 22 is shown in simplified form as having a triangular cross-section. The welded connection 22 can, for example, be designed as a weld seam. The spacer element 10 is arranged such that it is centered over a hole 24 arranged in the lower shell 6. The hole 24 has a diameter that is smaller than an inner diameter of the base body 14. A screw or bolt can be passed through the hole and the cavity inside the base body 14 in order to fasten the subframe 2 to the body or shell of the motor vehicle.

[0031] Fig. Figure 4 shows a further perspective view of the area of ​​the subframe according to the invention comprising the spacer element 10. The lower shell 6, the body 8, and the spacer element 10 comprising the base body 14 and the extension 16 are again shown. It can be seen that the extension 16 tapers trapezoidally from the base body 14, so that the welded joint 22 has a length—in other words, an extension along an edge of the extension 16 that terminates the extension 16—that is less than the extension of the base body 14 in the axial direction. In the illustrated embodiment, this axial direction coincides with the vertical.

[0032] In the illustrated embodiment, the extension 16 has a central recess 28. Such a recess 28, a similar recess, or several such recesses can be used to achieve weight reduction. The recess 28 has the shape of an oval elongated hole, with the long side of the elongated hole aligned parallel to the vertical. Furthermore, the base body has an approximately semicircular recess 30 on an upper edge. This recess 30 also reduces the weight and, when assembled, enables gas exchange between the interior of the base body 14 and its surroundings.

[0033] In Fig. Figure 5 shows a section of a side view of a second exemplary embodiment. The upper shell 4, the lower shell 6, the body 8, and the spacer element 10 are shown. Portions of the upper shell 4 are not shown, so that the spacer element 10 is visible. In the perspective shown, only the base body 14 is visible, while the extension is located behind the base body 14. The contact surface 20 of the body 8 is also visible. The contact surface 20 extends essentially vertically.

[0034] Fig. Figure 6 shows a schematic plan view of a section of a third embodiment of a subframe according to the invention. The view corresponds to a section along the line AA in Fig. 5. In the illustrated embodiment, the contact surface 20 or the part of the auxiliary frame having the contact surface 20 has a recess 32 through which an end section of the extension 16 passes. The recess 32 can be designed as a slot. Furthermore, the size of the recess 32 can be adapted to the extension 16 or the cross-section of the extension 16. Here, too, the extension 16 is connected to the contact surface 20 by the welded connection 22. In the illustrated embodiment, the welded connection is arranged on a side of the contact surface 20 opposite the base body 14 of the spacer element 10. However, it is also possible to arrange the welded connection 22 on the side of the contact surface 20 facing the spacer element 10. In the illustrated embodiment, the welded connection 22 is arranged on the side of the extension 16 facing the base body 14.However, it is also possible to arrange the welded joint on the side of the extension 16 facing away from the base body 14. It is also possible to use multiple welded joints. Thus, welded joints can be arranged in two, three, or all four of the previously described positions.

[0035] Fig. 7 shows a further possibility for implementing the welded joint 22. The fourth embodiment shown corresponds in principle to the second embodiment in that a recess 32 in the form of a slot is present in the contact surface 20, which is penetrated by an end portion of the extension 16. In this case, the weld seam 22 or the solder material used for the weld seam 22 almost completely or completely covers the end face of the extension 16. The weld seam 22 has been applied from the side of the contact surface 20 facing away from the base body.

[0036] Fig. 8 shows a further possible design of the spacer element 10 and thus a further schematically illustrated section of a fifth exemplary embodiment of a subframe according to the invention. In this case, the extension 16 of the spacer element 10 has a change or a kink 34, so that an end section of the extension 16 runs at least approximately parallel to the contact surface 20. The end section of the extension 16 runs at an angle of slightly less than 90°, for example at an angle between 60° and 100°, to a main portion of the extension 16. The extension 16 is in turn fixed to the contact surface 20 by means of a welded connection 22. In the exemplary embodiment shown, an end face 36 of the extension 16 is fixed to the contact surface 20 by the welded connection 22.

[0037] Fig. Figure 9 shows a section of a sixth embodiment of a subframe according to the invention in a schematic plan view. The spacer element 10 essentially corresponds to the spacer element of the first embodiment, as shown, for example, in Fig. 3. In Fig. In the embodiment shown in Figure 9, the extension 16 is thinner than the base body 14. In other words, the extension 16 has, at least in sections, a thinner material thickness than the base body 14. In this way, a further weight reduction can be achieved. A material thickness a of the base body 14 can be, for example, between 3 mm and 4 mm, and / or a material thickness b of the extension 16 can be, for example, between 2 mm and 3 mm. In a specific, exemplary embodiment, the material thickness a of the base body 14 can be 3.5 mm, and the material thickness b of the extension 16 can be 2.7 mm.

[0038] Fig. 10 shows a perspective view of a section of a seventh exemplary embodiment of a subframe according to the invention. The spacer element 10 has a plurality of recesses 38. The recesses 38 are located in the base body 14 of the spacer element 10 and have the shape of an elongated hole. For example, there may be at least or exactly two, at least or exactly three, at least or exactly four, or more than four recesses 38. The recesses can, for example, occupy a total of between 5% and 40% of the surface or the lateral surface of the base body 14.

[0039] Fig. Figure 11 shows the seventh embodiment in a further perspective view. It can be seen that a total of five slot-like recesses 38 are arranged in the base body 14 of the spacer element 10. Furthermore, the extension 16 also has a recess 28 in the form of a through hole. The recess 28 is smaller in size than the recesses 38. Furthermore, the welded joint 22 connecting the extension 16 to the contact surface 20 can be seen. In the illustrated embodiment, the welded joint 22 consists of several small spot welds.

[0040] Fig. 12 shows a perspective view of a section of an eighth embodiment of a subframe according to the invention. In this embodiment, too, recesses penetrating the base body 14 are present. In the illustrated embodiment, the recesses 38 are circular and arranged in several horizontally aligned lines at different heights surrounding the base body 14. The extension 16 also has a recess 28. In the illustrated embodiment, the recess 28 is oval. Alternatively, the recess 28 can also be circular. It is possible for the extension 16 to also have a plurality of recesses. The recesses can have the same shape or different shapes. For example, a second recess can be present which has the shape of an elongated hole.

[0041] In the Fig. 13 and Fig. Figure 14 shows a ninth embodiment of a subframe according to the invention. In the ninth embodiment, the extension 16 has a bead 40, which increases the stability and rigidity of the extension 16. In Fig. 13 shows a plan view in which it can be seen that the bead 40 protrudes laterally from the extension 16 on one side of the extension 16. In Fig. Figure 14 shows a perspective view from which it can be seen that the bead 40 was created by deforming the extension 16, so that the bead 40 forms a depression when viewed from one side of the extension 16, while the bead 40 represents a protrusion on the other side of the extension 16. The bead preferably extends horizontally along the extension 16.

[0042] All features of various exemplary embodiments, which are not logically mutually exclusive, can of course be combined with one another. Thus, different types of welded joints 22 can be easily combined with different configurations of the spacer element 10, for example, with regard to existing recesses or other details. The preferred example of a cylindrical base body was described in the exemplary embodiments. However, another prismatic base shape, for example, a cuboid base body, is also readily conceivable and offers the same advantages in terms of strength and rigidity as the cylindrical base body. List of reference symbols 2 subframes 4 upper shell 6 lower shell 8 Corpus 10 spacer element 12 spacer element 14 basic bodies 16 Extension 18 spacer 20 contact surface 22 Welded joint 24 holes 26 open space 28 recess 30 recess 32 recess 34 bend 36 front side 38 Recess (surface of base body) 40 bead F Direction of travel a sheet thickness b Sheet thickness 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] EP 3 369 645 B1

[0005]

Claims

[1] Subframe (2) for a motor vehicle, having an upper part and a lower part, and having at least one spacer element (10) arranged between the upper part and the lower part, wherein the spacer element (10) has a prismatic base body (14), characterized by that the spacer element (10) has a flat extension (16) which is connected to a contact surface (20) of the subframe (2) by at least one welded connection (22). [2] Subframe (2) according to one of the preceding claims, characterized by that the extension (16) extends in a plane parallel to a central axis of the base body (14). [3] Subframe (2) according to one of the preceding claims, characterized by that the welded joint (22) is a weld seam running parallel to a central axis of the base body (14). [4] Subframe (2) according to one of the preceding claims, characterized bythat the spacer element (10) is designed in one piece. [5] Subframe (2) according to one of the preceding claims, characterized by that the spacer element (10) is designed as a partially rolled sheet metal. [6] Subframe (2) according to one of the preceding claims, characterized by that a portion of the extension (16) penetrates a slot arranged in the contact surface (20). [7] Subframe (2) according to one of the preceding claims, characterized by that a material thickness of the spacer element (10) in the region of the extension (16) is less than a material thickness of the spacer element (10) in the region of the base body (14). [8] Spacer element (10) for a subframe (2) of a motor vehicle, with a cylindrical base body (14), characterized by a stiffening extension for connecting to a further element of the subframe, wherein the stiffening extension protrudes from the base body (14). [9] Spacer element (10) according to claim 8, characterized by that the stiffening extension is designed to be flat and a surface normal of a main surface of the stiffening extension is at least approximately perpendicular to a central axis of the base body (14) of the spacer element (16). [10] Motor vehicle with a subframe (2) or with a spacer element (10) according to one of the preceding claims.

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