Subframe for a motor vehicle

Abstract

Auxiliary frame for a motor vehicle, comprising: two longitudinal beams (11) each with a fastening section (11a) designed for coupling to a vehicle body, a first cross member (12) which is attached to the longitudinal members (11) and connects them in the transverse direction of the vehicle, a second crossbeam (13) arranged parallel to the first crossbeam (12), and two brackets (14), each designed as a sheet metal forming part and having one or more fastening sections (14d, 14e) designed for coupling wheel guide elements, wherein the brackets (14) are each attached (13) to one of the longitudinal beams (11) and the second crossbeam, characterized by the fact that the two brackets (14) which are each arranged at the end face of one of the longitudinal beams (11) to attach the second crossbeam (13) to the longitudinal beams (11).

Description

[0001] The invention relates to a subframe for a motor vehicle according to the preamble of patent claim 1.

[0002] A generic subframe is known from DE 102 60 529 A1. It has two longitudinal members and two cross members, which are directly connected to one another to form a quadrilateral frame. The front cross member and the two longitudinal members are made of tubular sections and are directly connected to one another, i.e., without the interposition of node elements. Fastening sections for wheel guide members are provided on separate brackets, which are attached to the longitudinal members. According to DE 102 60 529 A1, these brackets are attached solely to the longitudinal members and are intended to stiffen the longitudinal members. Furthermore, according to DE 102 60 529 A1, these brackets can be inserted into a gusset between the projecting end sections of the front cross member and the longitudinal members and connected to both.

[0003] Another subframe for a motor vehicle, comprising two longitudinal members, each with a fastening section designed for coupling to a vehicle body, a first cross member fastened to the longitudinal members and connecting them in the vehicle transverse direction, and a second cross member arranged parallel to the first cross member, is known from DE 10 2006 058 993 A1. The second cross member of this subframe is split longitudinally and composed of two shell elements. The two shell elements form opposing bearing receiving sections, between which a bearing of a wheel guide member is arranged. Furthermore, one of the shell elements of the second cross member has two additional fastening sections designed for coupling to a vehicle body.

[0004] Another subframe with two longitudinal members and two cross members is known from DE 199 22 800 A1. One of the cross members is connected to the longitudinal members via two cast light metal node elements. These node elements each incorporate several mounts for wheel guide links and a mount for a bearing element for connecting the subframe to the vehicle body. Additional mounts for bearing elements for connecting the subframe to the vehicle body are located on the longitudinal members, which extend through the other cross member for this purpose.

[0005] Further subframes are known from DE 30 48 754 A1, DE 33 40 973 A1, DE 101 20 934, EP 1 591 348 A2, DE 10 2005 045 295 A1, DE 10 2007 018 167 A1 and WO 2011 / 032631 A1.

[0006] Against this background, the object of the invention is to show alternatives to conventional subframe constructions.

[0007] In particular, the invention aims to create a subframe for a motor vehicle which is characterized by high rigidity and strength as well as a low component weight and can be manufactured cost-effectively.

[0008] In this respect, the subframe known from DE 10 2006 058 993 A1 appears to be in need of improvement, particularly with regard to its rigidity properties.

[0009] The subframe known from DE 199 22 800 A1, if made of steel, would result in a relatively high component weight. This is counteracted in DE 199 22 800 A1 by using light metal or plastic, which, however, leads to relatively high material costs.

[0010] The above-mentioned object is achieved by a subframe according to patent claim 1.

[0011] This avoids the disadvantages inherent in the state of the art explained above.

[0012] The subframe according to the invention enables an increase in rigidity and strength while reducing the overall weight.

[0013] The integrated brackets allow the wall thicknesses of the individual components of the subframe to be adjusted to the required level, resulting in optimal material utilization.

[0014] The interface structure according to the invention takes into account in particular the forces resulting from the wheel guidance, which are introduced into the subframe via suitable wheel guidance elements, as well as the force flow in the direction of the vehicle body.

[0015] In contrast to DE 199 22 800 A1, the subframe can be made of steel, which offers significant cost advantages.

[0016] Particular embodiments of the invention are the subject of further patent claims.

[0017] Preferably, the second cross member has two fastening sections designed for coupling to a vehicle body. By arranging the body-side fastening sections on the second cross member, the bracket to which the wheel guide members engage can be designed with a lower weight in terms of rigidity and strength than if the body-side fastening sections were also integrated into it, since the latter require differently oriented stiffening due to the direction of force application.

[0018] According to an advantageous embodiment, each bracket, viewed vertically relative to the installation position of the subframe, has a C-shape with two legs and a central section connecting these legs. The C-shape is open outwardly from a vehicle's longitudinal centerline. This enables a stable and space-saving attachment of the wheel guide elements to the brackets.

[0019] Preferably, a wing extending from the central section is pivoted between the legs. This supports the legs against each other, thereby providing additional stiffening to the console without great effort. This is particularly advantageous with regard to supporting the wheel guidance forces.

[0020] According to a further advantageous embodiment of the invention, a sheet metal bracket is arranged between the legs and connected to them. The sheet metal bracket is arranged in such a way that it stiffens the bracket in the longitudinal direction of the respective longitudinal member. This provides a further increase in rigidity, which can be used to reduce the wall thickness of the bracket and thus its weight.

[0021] The sheet metal tab can be designed as a separate insert that is welded between the legs. According to an advantageous embodiment, the sheet metal tab is formed by a wall section that extends from the leg opposite the respective longitudinal member. This wall section is welded at its free end to the leg on the longitudinal member side. A separate sheet metal element is not required in this case.

[0022] According to a further advantageous embodiment of the invention, the subframe has a main extension plane spanned by the longitudinal members and cross members. Each bracket has a first and a second fastening section for coupling a wheel guide member, wherein, with respect to the installation position of the subframe, the first fastening section is arranged above the main extension plane and the second fastening section is arranged below the main extension plane. By integrating several fastening sections for wheel guide members into the bracket, the manufacturing and assembly effort is reduced compared to conventional solutions in which a separate bracket is welded to a sheet metal structure for each connection point.

[0023] With the same objective in mind, a stabilizer bearing mount can be additionally designed on each bracket if required, since the associated forces can be absorbed by the bracket structure without any additional effort in terms of component weight.

[0024] According to a further advantageous embodiment of the invention, bushings for receiving rubber-metal bearings for acoustically decoupled connection of the subframe to the vehicle body or sleeves for rigid connection of the subframe to the vehicle body are attached to the fastening sections designed for coupling to the vehicle body.

[0025] The subframe according to the invention is particularly suitable for multi-link rear axles, with the second wishbone preferably being located in front of the first wishbone in the forward direction of travel. However, a reversed installation is also possible. Furthermore, a subframe according to the invention can also be used on a front axle.

[0026] The invention is explained in more detail below with reference to exemplary embodiments illustrated in the drawing. The drawing shows: Fig. 1 a spatial representation of a first embodiment of a subframe according to the invention from an angle from the front; Fig. 2 a spatial representation of the subframe according to the first embodiment from the rear bottom; Fig. 3 an exploded view of the subframe; Fig. 4 a first detailed view of a console of the subframe seen from the inside; Fig. 5 a second detailed view of the console seen from the outside; Fig. 6 a spatial view of a modification of the console; and in Fig. 7 a spatial partial view of a second embodiment of a subframe according to the invention seen from the side.

[0027] The first embodiment shows a subframe 10 for the rear axle of a passenger vehicle. However, the design principles explained below can also be applied to front axle subframes.

[0028] The subframe 10 comprises two longitudinal members 11 that run in the vehicle's longitudinal direction and are designed as bent tubular elements. Furthermore, the subframe 10 comprises two cross members, namely a first cross member 12, which is attached to the two longitudinal members 11 and connects them in the vehicle's transverse direction, and a second cross member 13, which also runs in the vehicle's transverse direction and is arranged parallel to the first cross member 12.

[0029] In the illustrated embodiment, the second cross member 13 is arranged in front of the first cross member 12 with respect to the forward travel direction V. Both cross members 12 and 13 are each composed of two shell elements 12a, 12b, 13a, 13b, which are formed as formed sheet metal parts, preferably made of sheet steel. The shell elements 12a, 12b, 13a, 13b are connected to one another, for example, by welding or riveting. The respective dividing plane extends in the vertical direction and in the transverse direction of the vehicle. The second cross member 13 forms a longitudinally split hollow profile body, while the first cross member 12 is open at the bottom.

[0030] The subframe 10 further comprises two brackets 14, each connecting a longitudinal member 11 to the front second cross member 13. The brackets 14 are attached to the front side of the respective longitudinal member 11, which extends forward to the rear shell element 13a of the second cross member 13.

[0031] As in particular Fig. 3, the rear shell element 13a of the second cross member 13 is shorter in the transverse direction of the vehicle than the front shell element 13b, so that end sections 13c of the front shell element 13b protrude laterally beyond the rear shell element 13a. The brackets 14 are arranged on the end face of the rear shell element 13a in the transverse direction of the vehicle and are fastened thereto, for example, welded. Furthermore, the brackets 14 are located behind the end sections 13c of the front shell element 13b with respect to the forward direction of travel V, wherein they are supported on the end sections 13c of the front shell element 13b in the forward direction of travel V and are preferably welded to them.

[0032] When viewed vertically relative to the installation position of the subframe 10, each of the brackets 14 has the shape of a "C" that is open outwardly from a vehicle longitudinal center axis X. In particular, each bracket 14 has a first leg 14a located at the front in the forward direction of travel V, a second leg 14b located at the rear with respect to the forward direction of travel V, and a central section 14c connecting these two legs 14a and 14b. The brackets 14 are each manufactured as a formed sheet metal part from a sheet metal blank, preferably from sheet steel, so that they have a substantially constant wall thickness.

[0033] Two fastening sections 14d, 14e are formed on the brackets 14 for coupling wheel guide members (not shown in detail). These fastening sections 14d, 14e are located, as particularly Fig. 1 and Fig. 2, on opposite sides of a main extension plane of the subframe 10, which is spanned by the longitudinal members 11 and the cross members 12 and 13. In the illustrated embodiment, the fastening sections 14d and 14e are formed by wall sections of the legs 14a and 14b, which have suitable openings for fastening corresponding control arm bearings. The fastening sections 14d and 14e are accessible from the side, so that the control arm bearings can be inserted between the legs 14a and 14b without great effort and fastened, for example, by means of through-bolts. Depending on the type and manner of connection of the wheel guide members, the fastening sections 14d and 14e can also be configured differently.

[0034] As in particular Fig. 4, one of the fastening sections 14d lies significantly above the main extension plane of the subframe 10. Furthermore, it is offset slightly toward the outside of the subframe 10 relative to the longitudinal member 11. For additional stiffening of this upper fastening section 14d, a wing 14f, which continues the essentially vertical central section 14c of the bracket 14, is pivoted between the legs 14a and 14b and accordingly angled relative to the central section 14c. The wing 14f is supported on the legs 14a and 14b and is fixed to them, for example, by being welded to the legs 14a and 14b with its side edges.

[0035] Such stiffening is not provided on the further fastening section 14e located below the main extension plane of the subframe 10, but is also possible.

[0036] Furthermore, in the illustrated embodiment, a stabilizer bearing holder 14g is formed on each bracket 14. This is in Fig. 5 on the rear outer side of the second leg 14b, which is located at the rear in the forward direction of travel V. For connecting a stabilizer mount (not shown in detail), a flat wall section with one or more openings on the rear second leg 14b, which is located below the associated longitudinal member 11, serves as an example here. Depending on the design of the stabilizer mount, the stabilizer mount mount 14g on the second leg 14b can also be designed differently. However, a stabilizer support - if one is required at all - can also be provided at another location on the subframe 10 or on the vehicle body.

[0037] Furthermore, a sheet metal bracket 15 is arranged between the legs 14a and 14b, which stiffens the corresponding bracket 14 in the longitudinal direction of the respective engaging longitudinal member 11. The sheet metal bracket 15 is inserted between the legs 14a and 14b at the level of the front side of the longitudinal member 11 and, in the illustrated embodiment, according to Fig. 5 is connected, preferably welded, to the inner sides of the legs 14a and 14b. The sheet metal tab 15 extends obliquely downward and outward from the upper fastening section 14d to the lower fastening section 14e. It forms an angle with the vertical direction of the vehicle in the range of preferably 5 to 60 degrees, and more preferably 15 to 40 degrees.

[0038] As in particular Fig. 3 shows, the first leg 14a can be provided with wall recesses 14h to reduce the weight, whereby a correspondingly angled web 14i remains for the support of the sheet metal tab 15.

[0039] In the first embodiment, the sheet metal tab 15 is a separate component which may have a different wall thickness than the bracket 14.

[0040] However, it is also possible to form the sheet metal tab 15 by a wall section 14j extending from the first leg 14a, as shown in Fig. 6. The wall section 14j is notched out of the first leg 14a except for a connecting edge 14k and is bent inward along the connecting edge 14k toward the second leg 14b. The free end 14l of the wall section 14j rests against the inner side of the second leg 14b on the longitudinal member side and is preferably attached thereto, for example, by welding.

[0041] The above-described design of the brackets 14 in sheet metal construction enables a design that is optimised in terms of stiffness and strength with regard to the wheel guidance forces to be absorbed, with minimal component weight and low manufacturing effort.

[0042] A total of four correspondingly designed fastening sections 11a and 13d are provided for fastening the subframe 10 to the vehicle body. Two of these are located at the rear end sections of the two longitudinal members 11 and two at the ends of the front second cross member 13. Fig. 1, the fastening sections 13d of the second cross member 13 are arranged on the projecting end sections 13c of the front shell element 13b and protrude slightly laterally beyond the brackets 14.

[0043] If the subframe 10 is to be acoustically decoupled from the vehicle body, rubber-metal bearings are attached to the mounting sections 11a and 13d, of which only the corresponding bushings 16 are shown in the figures. The bushings 16 are attached to the mounting sections 11a and 13d, for example, by welding.

[0044] Finally, two brake hose holders 17 are attached to the subframe 10.

[0045] The subframe 10 thus consists of eight sheet metal parts (12a, 12b, 13a, 13b, twice 14 and twice 15), two bent tubes (twice 11), four bushings (16) and two brake hose holders (twice 17), which are connected to each other preferably by welding.

[0046] Fig. 7 shows a second embodiment which differs from the first embodiment only in the design of the longitudinal members 11 and the fastening to the vehicle body.

[0047] Instead of tubular elements, components with an open profile cross-section are used as longitudinal members 11'. The illustrated longitudinal members 11' have a C-shaped profile cross-section, with the open side of the profile directed away from the vehicle's longitudinal center axis X toward the outside. The longitudinal members 11' can be designed as in DE 10 2006 058 993 A1 and connected to the brackets 14'.

[0048] The superimposed side flanks of the C-shaped profile of the longitudinal members 11' can, if necessary, be stiffened by a sleeve 18' arranged between them, which, in conjunction with suitable clamping bolts, simultaneously rigidly connects the subframe 10' to the vehicle body. The sleeves 18' are either attached to the respective longitudinal member 11' or are loosely inserted during assembly on the vehicle body.

[0049] A rigid attachment of the front cross member 13' to the vehicle body is carried out in the same way via sleeves 18', which are inserted between profile flanks of the front shell element 13b'.

[0050] The Fig. The rigid fastening of the subframe to the vehicle body shown in Figure 7 is also possible in the first embodiment.

[0051] Furthermore, it is possible to Fig. 7 shown longitudinal member 11' with open profile cross-section via rubber-metal bearings to the vehicle body.

[0052] Furthermore, suitable positioning projections can be formed on the second legs 14b of the brackets 14 for positioning the end faces of the longitudinal members 11 and 11', as described in DE 10 2006 058 993 A1.

[0053] The longitudinal members 11 and 11' initially extend essentially or predominantly parallel to the rear from the brackets 14, before then curving outwardly away from each other. The first cross member 12 is preferably arranged in the parallel region of the longitudinal members 11 and 11', directly in front of or in the region of the outward curvature.

[0054] Bearing points 12c for wheel guide links are also located on the first cross member 12. In the illustrated embodiment, these bearing points 12c are arranged in a central section and serve to connect a downwardly pivoting control arm. For this purpose, the first cross member 12 is designed as a profile that is at least partially open downwards, with opposing profile flanks each forming a bearing receiving section, and a bearing for a wheel guide link being arranged between these bearing receiving sections.

[0055] As already explained, the first cross member 12 is a longitudinally split component composed of two shell elements 12a and 12b, with the split plane running vertically perpendicular to the longitudinal members 11 and 11', respectively. However, a one-piece design is also possible. The same applies to the second cross member 13.

[0056] The subframes 10 and 10' described above are characterized by high rigidity and strength combined with low component weight. They can also be manufactured cost-effectively. The structure shown allows for optimal design of the wall thicknesses of the individual components, thus minimizing material usage. Furthermore, the available installation space is optimally utilized.

[0057] The invention has been explained in more detail above using preferred embodiments. However, it is not limited to these embodiments, but encompasses all embodiments defined by the patent claims. List of reference symbols 10, 10' subframe 11, 11' longitudinal beam 11a fastening section designed for coupling to the vehicle body 12, 12' first cross member 12a shell element 12b Shell element 12c bearing points 13, 13' second cross member 13a Shell element 13b Shell element 13c final section 13 fastening section designed for coupling to the vehicle body 14, 14' console 14a first leg 14b second leg 14c Middle section 14d fastening section designed for coupling a wheel guide member 14e fastening section designed for coupling a wheel guide member 14f wing 14g stabilizer bearing mount 14h wall recess 14i bridge 14j wall section 14k connecting edge 14l free end 15, 15' sheet metal tab 16 Bushing for rubber-metal bearing 17 Brake hose holder 18' sleeve V Forward direction X Vehicle longitudinal center axis

Claims

[1] Subframe for a motor vehicle, comprising: two longitudinal members (11), each with a fastening section (11a) designed for coupling to a vehicle body, a first cross member (12) which is fastened to the longitudinal members (11) and connects them in the transverse direction of the vehicle, a second cross member (13) arranged parallel to the first cross member (12), and two brackets (14), each of which is designed as a sheet metal part and has one or more fastening sections (14d, 14e) designed for coupling wheel guide members, wherein the brackets (14) are each fastened (13) to one of the longitudinal members (11) and the second cross member, characterized by , that the two brackets (14), each arranged on the end face of one of the longitudinal beams (11), in order to fasten the second cross beam (13) to the longitudinal beams (11). [2] Subframe according to claim 1, characterized bythat the second cross member (13) has two fastening sections (13d) designed for coupling to a vehicle body. [3] Subframe according to claim 1 or 2, characterized by that each console (14), when viewed in the vertical direction relative to the installation position of the subframe (10), has a C-shape with two legs (14a, 14b) and a central section (14c) connecting them, and the C-shape is open outwards away from a vehicle longitudinal center axis (X). [4] Subframe according to claim 3, characterized by that a wing (14f) projecting from the central section (14c) is pivoted between the legs (14a, 14b) and supports them against each other, stiffening the console (14). [5] Subframe according to claim 3 or 4, characterized by that a sheet metal tab (15) is arranged between the legs (14a, 14b) and connected to them, and stiffens the bracket (14) in the longitudinal direction of the respective engaging longitudinal member. [6] Subframe according to claim 5, characterized by that the sheet metal tab (15') is formed by a wall section (14j) which extends from the leg (14a) opposite the respective longitudinal member (11) and which is welded at its free end (14l) to the leg (14b) on the longitudinal member side. [7] Subframe according to one of claims 1 to 6, characterized by in that the subframe (10) has a main extension plane which is spanned by the longitudinal members (11) and cross members (12, 13) and each bracket (14) has a first and a second fastening section (14d, 14e) for coupling a wheel guide member in each case, wherein with respect to the installation position of the subframe (10) the first fastening section (14d) is arranged above the main extension plane and the second fastening section (14e) is arranged below the main extension plane. [8] Subframe according to one of claims 1 to 7, characterized bythat a stabilizer bearing holder (14g) is formed on each bracket (14). [9] Subframe according to one of claims 1 to 8, characterized by that bushings (16) for receiving rubber-metal bearings for the decoupled connection of the subframe (10) to the vehicle body or sleeves (18') for the rigid connection of the subframe (10') to the vehicle body are attached to the fastening sections (11a, 13d) designed for coupling to the vehicle body. [10] Subframe according to one of claims 1 to 9, characterized byin that the second cross member (13) has a front and a rear shell element (13a, 13b), wherein the rear shell element (13a) of the second cross member (13) is shorter in the transverse direction of the vehicle than the front shell element (13b), so that end sections (13c) of the front shell element (13b) project laterally beyond the rear shell element (13a), the brackets (14) are arranged on the end face of the rear shell element (13a) in the transverse direction of the vehicle and are fastened to the latter, and the brackets (14) are behind the end sections (13c) of the front shell element (13b) with respect to the forward direction of travel (V), wherein they are supported on the end sections (13c) of the front shell element (13b) in the forward direction of travel (V).

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