wishbone for a motor vehicle

Abstract

A wishbone (1) for a motor vehicle, in a single-shell construction with a shell (2), with a wheel leg (3), having a wheel connection point (5) for a wheel carrier and a first chassis connection point (6) for a chassis, as well as a chassis leg (4) extending from the wheel leg (3), having a flange (12) formed on the wheel side, an opposite flange (13) formed on the chassis side, and a second chassis connection point (7) for the chassis, wherein the chassis leg (4) has a desired deformation region (4.1), characterized in that the desired deformation region (4.1) has a recess (16) in a base (11) of the shell (2) and a cutout (19) adjacent thereto in the flange (12) formed on the edge of the base (11) on the wheel side, wherein the chassis leg (4) has a Wishbone (1) has a stamping (11.1) spaced apart from the wishbone, within which the recess (16) is arranged.

Description

[0001] The invention relates to a wishbone for a motor vehicle, having the features of the preamble of claim 1.

[0002] DE 10 2010 024 634 A1, which is closest to the invention, discloses a motor vehicle control arm, in particular a motor vehicle wishbone, comprising a single-shell base body with bearing sections connected to the base body, wherein the base body has a flat base body base with bent side legs arranged thereon. A recess is provided in at least one side leg between two bearing sections.

[0003] DE 20 2015 103 767 U1 discloses a wishbone for a motor vehicle, which is designed in a single-shell construction with a shell, with a wheel leg, having a wheel connection point for a wheel carrier and a first chassis connection point for a chassis, and a chassis leg extending from the wheel leg, having a second chassis connection point for the chassis. The shell has a predetermined deformation point on the wheel leg for initiating a planned deformation when a force acts along the wheel leg, wherein the predetermined deformation point is arranged on the wheel side with respect to the chassis leg. The predetermined deformation point can have a cutout in the edge of a flange, which is located on a side of the wheel leg facing away from the chassis leg.

[0004] Control arms are a component of the vehicle's wheel suspension. In motor vehicles, such a control arm connects the wheel carrier to the vehicle body, typically to the chassis or a subframe. Such a control arm normally has two chassis-side connection points and one wheel-side connection point. The chassis-side connection points, which are connected by means of an articulated connection, e.g. using metal-rubber composite bearings, are usually aligned with the X-axis (i.e. the longitudinal axis) of the vehicle when installed, so that a pivoting movement of the wheel-side connection point in the YZ plane is possible. However, deviations from this are also possible, so that the pivot axis runs at an angle to the X-axis. The main function of the control arm is in any case to absorb horizontal forces, i.e. forces lying in the XY plane, together with other suspension components.

[0005] A typical control arm design is more or less L-shaped, with the control arm roughly divided into two legs, one of which connects a chassis-side connection point with the wheel-side connection point and extends essentially transversely to the X-axis. When the control arm is aligned horizontally, this leg and thus the connection between the two connection points runs roughly along the Y-axis (transverse axis). Another leg is usually connected to the first leg near the wheel-side connection point and runs at an angle to it. The second chassis-side connection point is located at the end of this leg.

[0006] In addition to forged wishbones, which are usually made of light metal or steel, control arms manufactured as formed sheet metal parts are also known in the prior art. In order to give such a control arm the necessary strength, the sheet metal is given a profile through a suitable forming process (e.g. drawing), which typically gives it a shell-like structure. In addition to double-shell control arms, in which two shells enclose an interior space and provide mutual stability through their connection, single-shell control arms are also known, in which stability results solely from the structure of a single shell, the essential component of which is usually a flange on the edge. In addition, embossing, beads or similar features can be incorporated into the interior between the edges to further increase stability.

[0007] Control arms are typically classified as secondary components designed to deform when subjected to overload (which can occur, for example, due to driving too fast through a pothole, possibly combined with emergency braking), thus absorbing energy before deformation of primary components, such as the subframe or steering knuckle, occurs. In addition to the requirement of sufficient stability during normal vehicle operation, the control arm is also required to yield in a planned or controlled manner by deforming when a certain load is exceeded.

[0008] To ensure a specified sequence of yielding of the suspension components, the control arm must meet specific requirements with regard to both longitudinal (X-direction) and transverse (Y-direction) yielding. Particularly complex in this regard is the contribution of a force acting in the X-direction, which stresses the control arm in compression, bending, and torsion. It is difficult to determine which of these loads primarily contributes to the component's yielding. Due to its open design, a single-shell control arm is relatively sensitive to torsional loading, which makes it difficult to set the load threshold for scheduled yielding. Some attempts are made to remedy this by increasing the thickness of the shell material, although this has a detrimental effect on the weight of the control arm.

[0009] EP 2 399 765 B1 shows a motor vehicle control arm with a single-shell base body and bearing sections connected to it. The base body has a base and bent flanges arranged laterally thereon, with a recess provided in a flange between two bearing sections. The recess has a collar, at least in sections. One embodiment shows the recess between a chassis-side and a wheel-side bearing section. A mounting opening designed as a passage is located near the recess.

[0010] DE 102 05 639 A1 shows a wishbone for a wheel suspension of a motor vehicle, which can be designed, for example, as a multi-part sheet metal construction, with sheet metal strips welded to the edges of a sheet metal plate for reinforcement. The sheet metal plate has a through-hole formed by two spaced-apart round holes and an elongated web opening connecting them.

[0011] DE 100 29 189 A1 discloses a wishbone for a wheel suspension, which is essentially formed by a one-piece cast part made of steel or a light metal alloy. Ribs or flanges extending transversely to the plane of the control arm are formed on the edge of a flat area extending in the plane of the control arm. The flat area also has a kidney-shaped opening and two dumbbell-shaped openings.

[0012] DE 10 2010 020 520 A1 discloses a control arm for a wheel suspension with a wheel-side and a body-side bearing point, as well as a control arm base extending between them. A material weakening is incorporated into the control arm base to influence the ductile deformation properties of the control arm. The material weakening is a dumbbell-shaped recess with two holes and a web opening located between them. The recess is located in the area of a bearing point subject to compressive stress, and the web opening can, in particular, run perpendicular to the direction of force.

[0013] US Patent No. 8,251,386 B2 shows a wishbone welded from three sheet metal parts, in which two sheet metal strips are welded to the edges of the arms of the control arm. When installed, one of the welded sheet metal strips is located at the front and one on a side facing the chassis. A control arm base extending in the direction of the control arm plane has a through-hole on one side and, on the other side, a curved section on each side of the through-hole, which slopes upwards toward one of the sheet metal strips.

[0014] KR 10 2007 0 055 804 A shows a suspension control arm with front and rear connection points, as well as a connection point for a wheel carrier. The control arm has a two-shell design, with a reinforcement element inserted between the two shells, located in an edge area on the side facing the wheel carrier.

[0015] EP 1 160 106 A2 shows a wishbone for a motor vehicle formed from welded steel sheets. A sheet metal part forms a shell of the control arm. The flange-like bent sides of the shell are connected by a welded steel sheet. In an area where the arms of the control arm meet, an additional reinforcement plate is welded in.

[0016] In view of the state of the art shown, there is still room for improvement in the provision of a wishbone which has the lowest possible weight and at the same time reliably yields in a predetermined manner when overloaded by a force acting along the longitudinal axis of the vehicle.

[0017] The invention is based on the object of providing a lightweight wishbone which deforms in a predetermined manner when overloaded due to a force acting along the X-axis.

[0018] According to the invention, the object is achieved by a wishbone having the features of claim 1.

[0019] Shown is a wishbone for a motor vehicle, formed in a single-shell design with a shell, with a wheel leg, having a wheel connection point for a wheel carrier and a first chassis connection point for a chassis, as well as a chassis leg extending from the wheel leg, having a flange formed on the wheel side, an opposite flange formed on the chassis side, and a second chassis connection point for the chassis, wherein the chassis leg has a desired deformation region. The desired deformation region has a recess in a base of the shell and an adjacent cutout in the flange formed on the edge of the base on the wheel side, wherein the chassis leg has an embossed portion spaced from a mounting opening of the wishbone, within which the recess is arranged.

[0020] The subclaims relate to advantageous embodiments of the invention.

[0021] It should be noted that the features and measures listed individually in the following description can be combined with one another in any technically reasonable manner and demonstrate further embodiments of the invention. The description further characterizes and specifies the invention, particularly in conjunction with the figures.

[0022] The invention provides a wishbone for a motor vehicle. The wishbone is of single-shell construction or single-shell design with one shell. As already explained above, “single-shell” means that the structure of the wishbone is essentially formed by sheet metal (or possibly comparable plate-like material) that is shaped like a shell (open on one side) and thus has a curved structure and / or angled edge regions that form flanges. This type of wishbone is to be distinguished from double-shell designs, in which two shells, which are, for example, welded together, enclose an interior space. The shell preferably consists of a single layer of sheet metal, in particular sheet steel. In addition, it is also conceivable to use a multi-layer shell (where the metal sheet is reinforced, e.g.by using an additional welded metal sheet or a fiber-reinforced plastic layer), or even a shell made entirely of fiber-reinforced plastic.

[0023] The wishbone comprises a wheel leg, which has a wheel connection point for a wheel carrier and a first chassis connection point for a chassis. These connection points are points or areas where a direct or indirect connection to the wheel carrier or chassis can be established. Such a connection point can be provided, for example, by a bearing bush, a bearing journal, a ball joint socket, or the like. It is also known in the prior art to connect a ball joint socket as a separately manufactured component to the actual shell of the wishbone by riveting, screwing, or the like. In such a case, the part of the shell that is provided for attaching the ball joint socket and has, for example, bores for this purpose can also be regarded as a connection point. The wheel leg represents a part of the wishbone that, when installed, extends from the chassis (e.g., a subframe) to the wheel carrier.The wheel limb's course usually roughly corresponds to the vehicle's Y-axis. Of course, the wheel limb doesn't have to be straight, but can have a curved edge on at least one side, for example.

[0024] The wishbone also has a chassis leg that extends from the wheel leg and has a second chassis connection point for the chassis. The chassis leg is located on the side of the wishbone facing the chassis and runs at an angle to the wheel leg, from which it extends or into which it joins. As is usual with single-shell designs, the two legs are usually formed as a single piece, i.e. they consist of the same piece of material, e.g., sheet metal or similar. The legs are at least predominantly formed by the shell. Typically, the wishbone is given an L-shaped structure by the two legs. The contour at the transition from one leg to the other is usually curved, so that there is no corner or kink there. Even with a structure that can be described as L-shaped, the course of the chassis leg is usually not perpendicular to the wheel leg.However, the imaginary connecting lines between the wheel connection point and the first chassis connection point on the one hand, and the first and second chassis connection points on the other, often run approximately at right angles. When installed, the first and second chassis connection points are normally arranged approximately along the X-axis of the vehicle to ensure pivoting movement of the wishbone around the X-axis, but deviations from this are also possible.

[0025] The chassis leg (more precisely, the part of the shell that belongs to the chassis) has a target deformation region. Such a target deformation region serves to initiate a planned deformation when an applied force is applied. In particular, this can be a force that acts along the X-axis of the vehicle. In order to prevent unnecessary damage to other (particularly primary) vehicle components, a planned deformation is initiated by the target deformation region. The deformation normally begins in the target deformation region or is possibly limited to this area. The term "planned" is of course not intended to imply that the exact course or extent of the deformation can be planned in the event of an overload, but merely that the deformation itself is planned.

[0026] As already mentioned, the desired deformation area has a recess in a base of the shell and an adjacent cutout in a flange formed on the edge of the base. The recess, which can also be referred to as a through opening, is arranged in the base of the shell. Such a base normally runs at least partially in or parallel to a plane spanned by the aforementioned connection points. However, the base does not have to be completely flat, but can itself be structured, e.g., by embossing, beads, or the like. The recess is naturally arranged in a part of the base that belongs to the chassis leg. A flange is formed on the edge of the base, at least in the area of the chassis leg. The wishbone normally has additional flanges on the edges, as is usual with single-shell control arms.The flange is preferably formed integrally with the base and can, for example, be formed by bending or deep-drawing a sheet metal part. The flange naturally runs at an angle to the plane of the base and can, for example, run partially orthogonal to it. It has a cutout that is adjacent to the recess. One could also say that the cutout is located in the region of the recess. For example, the cutout can be arranged transversely to the direction of travel of the chassis leg to the side of the recess. It can be arranged in a region of the flange that is closest to the recess. It is preferably an edge-side cutout of the flange, i.e. the edge of the cutout is formed by the edge of the flange.

[0027] The combination of the recess in the base area and the cutout in the flange area allows for significantly better control of the planned yielding when a force is applied in the X-axis. The load is primarily due to torsion and bending, with the inventive combination of features leading to better utilization of the material when forces act in the X-direction and resulting in an additional reaction force that would not be possible without the combination of features. It has been shown that the torsional load can be stabilized so that the main load is due to bending and compression (load in the longitudinal direction of the chassis leg). However, the single-shell structure of the wishbone can absorb such loads better than torsional loads.

[0028] At the same time, it should be noted that no material reinforcements are necessary; on the contrary, material is removed, thereby reducing the weight of the wishbone. It appears that the torsional load is largely due to the open profile of a single-shell control arm, whereby the inventive omission or removal of material and the resulting reduced cross-section instead causes a compression load. The recess allows stresses to be localized, i.e., the cross-section of the wishbone is most heavily stressed in this area. If only the cutout were provided in the area of the flange, it would have to have a very small radius to localize the stresses in a similar way, which in turn would impair the fatigue strength and thus the service life of the wishbone. This would also not be able to stabilize the torsional load.In other words, due to the recess, the cutout can have a larger radius, whereby the fatigue strength can be further optimized by appropriately coordinating the radii of the recess and the cutout.

[0029] As already mentioned above, the chassis leg has an embossed portion within which the recess is arranged. Such an embossed portion, which is introduced into the base of the shell within the chassis leg, represents a depression produced by embossing, which has a base area that runs essentially in the direction of the plane spanned by the connection areas or parallel to the base of the shell. The edges of the embossed portion, which run at an angle to the plane or to the adjacent parts of the base, generally serve to locally stiffen the wishbone. The embossed portion can be elongated, with a greater extent in the direction of the chassis leg than transversely to it.

[0030] A wishbone often has a mounting hole, which is often located in a connection area where the two legs meet. Such a mounting hole runs within the base and can, for example, have a collar on the edge. It serves to allow access through the shell when assembling or disassembling the wheel suspension. In this case, the aforementioned embossing is arranged at a distance from the mounting hole of the wishbone. One could also say that the embossing is located within the control arm plane, laterally offset from the mounting hole. This naturally also means that the recess arranged within the embossing is different from the mounting hole and spaced apart from it.

[0031] The recess can fundamentally have various shapes, for example, it can be polygonal or irregularly shaped. However, the recess is preferably circular or elliptical. This design helps to avoid local weak points in the areas adjacent to the recess. Such weak points, which could be the corners of a polygonal shape, for example, can under certain circumstances make it difficult to control the deformation behavior and thus to ensure planned yielding. The size of the recess can vary and naturally also depends on the size of the wishbone. According to one design, the recess has a radius between 3 and 25 mm, preferably between 4 and 20 mm. In the case of an elliptical design, the specified values can refer to the semi-major axis.

[0032] Preferably, the base runs adjacent to the recess at least predominantly parallel to its opening plane without a collar. In the above-mentioned design, this is the part of the base that belongs to the embossed portion. In contrast to recesses that are surrounded by a collar in the form of a passage that is angled relative to the opening plane and relative to the surrounding material, it is sufficient and under certain circumstances even advantageous if the recess does not have such a collar. Compared to a design with a collar, the manufacturing process is of course also simplified because an additional forming step for producing the collar is eliminated. It goes without saying that the base does not necessarily have to be exactly flat, but can in some cases have a slight inclination or curvature, which is, however, so slight that it does not have the stabilizing effect that a collar would have.

[0033] Normally, the chassis leg has flanges on both sides, one of which is located on the chassis side and the other on the wheel side.

[0034] In principle, the cutout can be formed in either of the two flanges mentioned. However, as mentioned above, it is located in the flange formed on the wheel side of the chassis leg. This is especially true if the wheel-side flange runs diagonally backwards with respect to the X-axis and is positioned diagonally rearward of the shell. When a force acts in the direction of the X-axis, a planned yielding can be achieved more effectively than if the cutout is located in the opposite, chassis-side flange.

[0035] In principle, it is conceivable for the cutout to be polygonal, for example. However, the inner corners of such a polygonal cutout can form particular structural weak points, which can have a detrimental effect on the deformation behavior. The cutout advantageously has a rounded contour. It has been shown that a rounded structure without corners enables better control of the give of the handlebar. In particular, the cutout can have a circular arc-like contour. The contour does not have to be continuous and exactly circular, i.e. it does not necessarily have to be described by a single radius, but parts of the contour can be exactly circular arc-shaped in themselves. In particular, the circular arc-like contour can have a radius between 30 mm and 250 mm, preferably between 40 and 200 mm.By selecting the radius, the deformation behavior of the wishbone can be controlled specifically according to requirements.

[0036] Preferably, the flange adjacent to the cutout runs at least predominantly parallel to its opening plane without a collar. This means that it is sufficient and under certain circumstances even advantageous if the cutout does not have a collar, i.e. is not designed as a through-hole. Here, too, the omission of the collar simplifies the manufacturing process without impairing the intended deformation behavior of the wishbone. The flange does not necessarily have to be exactly flat, but can in some places have a slight inclination or curvature, which is, however, so slight that it does not have the stabilizing effect of a collar. In cases where the flange is slightly curved overall in the area of the cutout, the opening plane of the cutout is normally also curved and not a plane in the mathematical sense.However, it can usually be considered as flat, at least in some areas, with the flange then running parallel to this (local) plane.

[0037] Preferably, the cutout is offset diagonally to the recess with respect to the X-axis and the Y-axis. This means that the cutout is offset neither exactly in the X-direction nor exactly in the Y-direction from the recess, but at an angle to both directions. Since both the cutout and the recess have a certain extent, the exact angle cannot be determined; however, the center of the recess can be offset from the center of the cutout, for example, at an angle between 30° and 60° to the X-axis. Such a design is particularly advantageous if the flange itself runs at an angle to the aforementioned axes.

[0038] Further advantageous details and effects of the invention are explained in more detail below with reference to an embodiment illustrated in the figures. Fig. 1 a plan view of a wishbone according to the invention, Fig. 2 a side view according to direction II in Fig. 1; and Fig. 3 a sectional view along the line III-III in Fig. 1.

[0039] In the different figures, identical parts are always provided with the same reference symbols, which is why they are usually only described once.

[0040] Fig. 1 shows a plan view of a control arm 1 according to the invention. For better orientation, the X, Y, and Z axes of the vehicle are shown in the figures according to the intended installation position. In the present case, it is a lower front control arm 1 for a motor vehicle, e.g., a car or truck. The control arm 1 is approximately L-shaped or curved, with a wheel leg 3 extending essentially along the Y-axis and a chassis leg 4 extending therefrom or merging into a connection area 17. For connection to a wheel carrier (not shown), the control arm 1 has a wheel connection point 5, on which a first ball joint receptacle 8 is formed. In the present case, the control arm 1 is formed by a shell 2 consisting of a single steel sheet, with a base 11, on the sides of which three flanges 12, 13, 14 are formed.These serve to provide the wishbone 1 with the necessary stability against the forces occurring during normal operation, both within the horizontal XY plane and in the Z direction. In the connection area 17, a mounting opening 15 designed as a through-hole is provided, through which a tool can be inserted during assembly or disassembly of the vehicle suspension.

[0041] While the wheel connection point 5 is formed at one end of the wheel leg 3, a first chassis connection point 6 is formed at an opposite end thereof, on an extension 18, which serves for attachment to a chassis of the motor vehicle (not shown). At the end of the chassis leg 4 is a second chassis connection point 7, which also serves for attachment to the chassis. The first and second chassis connection points 6, 7 provide a pivot axis on the chassis, which in the present case is inclined by approximately 10° relative to the X-axis. The first and second chassis connection points 6, 7 are formed here by a second and third ball joint receptacle 9, 10.

[0042] If forces in the X-direction occur during a load that exceed a specified value, it must be ensured that the control arm 1 deforms first before primary vehicle components, such as a subframe, deform. To ensure this, the chassis leg 4 has a target deformation area 4.1, through which a planned deformation of the control arm 1 can be initiated.

[0043] Here, on the one hand, a circular recess 16 is provided, which is arranged within a stamping 11.1 of the base 11. The stamping 11.1 serves (if necessary together with other stampings and / or beads not shown here) to stabilize the wishbone 1 and in this respect complements the flanges 12, 13, 14. The stamping 11.1 and thus also the recess 16 are arranged at a distance from the assembly opening 15. As shown in the side view of Fig. 2, a cutout 19 with a circular arc-like contour is formed in the flange 12, which is arranged on the wheel side of the chassis leg. More precisely, the cutout 19 is arranged in a section 12.1 of the flange 12, which is closest to the recess 16. As can be seen in the plan view in Fig. 1, the cutout 19 is offset by approximately 45° to the X-axis relative to the recess 16. While the radius of the recess 16 can be, for example, 15 mm, the radius of the cutout 19 can be significantly larger, for example, 100 mm.

[0044] The sectional view in Fig. Figure 3 shows that neither the recess 16 nor the cutout 19 have a collar. Rather, the base 11 extends adjacent to the recess 16 parallel to its opening plane without a collar. Accordingly, the flange 12 extends adjacent to the cutout 19 parallel to its opening plane without a collar.

[0045] Due to the interaction of the recess 16 with the cutout 19, the loading caused by torsional forces is largely suppressed when a force is applied in the X-direction (longitudinal direction of the vehicle). Instead, a significant bending load is created, as well as a compressive load acting along the chassis leg 4. The compliance with these loads can be relatively well controlled, for example, by varying the size of the recess 16 and / or the cutout 19. List of reference symbols: 1 wishbone 2 bowls 3 wheel legs 4 chassis legs 4.1 Target deformation range 5 bike connection point 6 first chassis connection point 7 second chassis connection point 8, 9, 10 ball joint mount 11 Floor 11.1 Embossing 12, 13, 14 flange Section 12.1 15 Mounting opening 16 Recess 17 Connection area 18 Extension 19 Excerpt X X-axis Y Y-axis Z Z-axis

Claims

[1] A wishbone (1) for a motor vehicle, in a single-shell design with a shell (2), with a wheel leg (3) having a wheel connection point (5) for a wheel carrier and a first chassis connection point (6) for a chassis, as well as a chassis leg (4) extending from the wheel leg (3), having a flange (12) formed on the wheel side, an opposite flange (13) formed on the chassis side, and a second chassis connection point (7) for the chassis, wherein the chassis leg (4) has a desired deformation region (4.1), characterized by that the desired deformation region (4.1) has a recess (16) in a base (11) of the shell (2) and a cutout (19) adjacent thereto in the flange (12) formed on the edge side of the base (11) and on the wheel side, wherein the chassis leg (4) has an embossed portion (11.1) spaced from a mounting opening (15) of the wishbone (1), within which the recess (16) is arranged. [2] Wishbone according to claim 1, characterized by that the recess (16) is circular or elliptical. [3] Wishbone according to one of the preceding claims, characterized by that the base (11) adjacent to the recess (16) runs predominantly or completely parallel to its opening plane. [4] Wishbone according to one of the preceding claims, characterized by that the cutout (19) has a rounded contour. [5] Wishbone according to one of the preceding claims, characterized by that the cutout (19) has a circular arc-like contour. [6] Wishbone according to one of the preceding claims, characterized by that the flange (12) adjacent to the cutout (19) runs predominantly or completely parallel to its opening plane. [7] Wishbone according to one of the preceding claims, characterized bythat the cutout (19) is offset diagonally to the recess (16) with respect to the X-axis and the Y-axis.

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