Torsible rear axle

Abstract

The present invention relates to a motor vehicle axle (10'). It comprises: two suspension arms (12'), each having a front end and a rear end; a cross member (16') connecting the suspension arms at a T-junction in an intermediate zone, said two arms each having a rear portion forming two rear angles with said cross member (16'); two support cups (44'), having, on the one hand, a top face (65') for receiving a spring, and on the other hand, a front edge (48') welded to said cross member and a lateral edge (50') welded to said rear portion. Said front edge (48') of said two cups (44') has an abutment surface (74') against said cross member, larger than the cross-section of said two cups (44') along a plane Pp' extending perpendicularly to said top face (65') and along said front edge (48'). Figure to be published with the abbreviation: Fig. 2

Description

Title of the invention: Torsible rear axle

[0001] The present invention relates to a torsional rear axle of a motor vehicle.

[0002] These torsionally flexible rear axles usually comprise a pair of suspension arms connected to each other by a cross member. The suspension arms have a front end pivotally mounted on the underside of the chassis, and at the opposite end, a rear end receiving a wheel support to accommodate a wheel.

[0003] The crossmember connects the two suspension arms in a T-shape at an intermediate point between their front and rear ends. Each arm has a rear portion extending from this intermediate point to its rear end, forming two rear angles with the crossmember. Two support cups are mounted at these rear angles to receive two coil springs installed vertically. Each cup has a top face to receive the spring. Furthermore, each cup has a front edge welded to the crossmember and a side edge welded to the rear portion of the corresponding arm.

[0004] The cups not only allow the helical springs to be received in support, but also to maintain the arms and the cross member in a fixed position in substantially perpendicular directions.

[0005] Such torsional rear axles are compact and relatively lightweight. Therefore, they are commonly fitted to various motor vehicles, both commercial and non-commercial, and generally entry-level models.

[0006] Furthermore, these different motor vehicles are manufactured on a common platform with components having geometries specific to each vehicle. Nevertheless, efforts are made to reduce, as much as possible, the number of different parts for the different types of vehicles.

[0007] However, the axle elements of some vehicles are more or less stressed compared to the axle elements of other vehicles made on the same platform.

[0008] In particular, the forces exerted on the suspension arms and on the cross member can locally stress the cross member via the cups.

[0009] Also, a problem which arises and which the present invention aims to solve is to provide a torsible rear axle which can be obtained on the same platform in different possible architectures, without compromising the fatigue resistance of certain areas for certain architectures.

[0010] In order to solve this problem, and according to a first object, a rear axle for a motor vehicle is proposed, comprising: a pair of suspension arms, each of the suspension arms having a front end adapted to be pivotally mounted on a vehicle chassis and a rear end receiving a wheel support; a cross member connecting the suspension arms in a T-shape in an intermediate zone situated between said front end and said rear end, said two arms each having a rear portion extending from said intermediate zone to said rear end and forming two rear angles with said cross member; and two support cups mounted respectively in said two rear angles, each of said cups having, on the one hand, a top face to be able to receive a spring in support, and on the other hand, a front edge welded to said cross member and a side edge welded to said rear portion.

[0011] And, said front edge of said two cups has an application surface against said cross member, greater than the section of said two cups along a plane extending perpendicularly to said upper face and along said front edge.

[0012] Thus, a feature of the invention lies in the implementation of a cup whose contact surface on the cross member is greater than the cross-section of the cup, measured behind the front edge. In this way, the contact area between the cup and the cross member is increased and, consequently, the stresses exerted by the cups on the cross member are reduced per unit area. As a result, the fatigue resistance of the cross member is preserved locally.

[0013] According to a first embodiment, the front edge has a lateral extension, such that the front edge has a length greater than the length of the straight section. In other words, the cup has a local widening at its edge where it connects to the cross member. This increases the length of the connection between the front edge and the cross member.

[0014] The cups are connected to the cross member by means of a weld joint applied between the front edge and the cross member.

[0015] According to this first embodiment, the front edge extends opposite the side edge. In other words, the edge comes to rest against the cross member opposite the adjacent arm.

[0016] According to a second embodiment, the rim is curved opposite the upper face along generatrices parallel to the plane to conform to the surface of the cross member. Thus, the curvature of the rim is achieved in such a way as to cooperate with the surface of the cross member and ensure a larger contact area. Furthermore, a weld bead is also applied to the joint between the rim and the cross member to bond them together. In this way, the stresses exerted by the front rim of the cup on the cross member are distributed over a larger area and thus do not locally damage the cross member.

[0017] The application surface of the edge on the cross member is to be compared to the application surface that the front edge of the cup would have if it corresponded to the edge of the cup, without its lateral extension corresponding to the first embodiment variant.

[0018] Furthermore, according to the invention, each of said cups has a free rear edge opposite said front edge and a free lateral edge opposite said welded lateral edge, and said free edges meet to form an arc. In this way, the overall size of the cups is reduced without reducing their resistance to deformation or their performance in holding the arms and the crossmember together.

[0019] Moreover, according to the invention, the free edges of each of the cups are preferably curved away from the upper face. In other words, the cups have a rolled edge. This stiffens the edge of the cup and thereby increases its resistance to deformation.

[0020] Furthermore, according to the invention, said cross member is tubular. The two ends of the tubular cross member are then notched to form a "wolf's mouth" to receive the arms. The arms and the ends of the cross member are then joined together by means of weld beads formed at the joint between the arms and the ends.

[0021] Advantageously, and according to the invention, each of said cups has a circularly symmetrical deformation extending outward from said upper surface. Thus, the ends of the helical springs then lie flat against the upper face of the cup around the circular deformation. In this way, the ends of the helical springs are held in a fixed position relative to the cups along their mean plane.

[0022] Also, according to another object, the invention relates to a motor vehicle comprising a torsional rear axle, as described above.

[0023] Other features and advantages of the invention will become apparent from the following description of particular embodiments of the invention, given by way of example but not limitation, with reference to the accompanying drawings in which:

[0024] [Fig.1] is a schematic top perspective view of a rear axle of a motor vehicle in accordance with the prior art;

[0025] [Fig.2] is a partial schematic top perspective view of a rear axle in accordance with the invention and according to a first embodiment;

[0026] [Fig.3] is a schematic detail view of the object in [Fig.2]; and,

[0027] [Fig.4] is a schematic perspective detail view of an element of the invention analogous to that of [Fig.3] according to a second variant of execution.

[0028] Figure 1 shows, viewed from above, a rear axle 10 of a motor vehicle according to the prior art. Figures 2 to 4 show the modifications made to this rear axle 10 which are the subject of the invention according to two embodiments.

[0029] The rear axle 10 is situated in an orthogonal coordinate system X, Y, Z of the motor vehicle, in which the X axis extends along a longitudinal front-to-back direction, oriented towards the rear; the Y axis extends along a transverse direction of the vehicle, oriented from left to right when in motion; and the Z axis extends along a vertical direction, oriented away from the ground. Also, the two suspension arms 12, 14 are tubular.

[0030] The rear axle 10 has a left suspension arm 12 and an opposite right suspension arm 14. The two suspension arms 12, 14 are symmetrical to each other with respect to a median plane Pm.

[0031] In addition, the two suspension arms 12, 14 are connected together by a tubular cross member 16.

[0032] The left suspension arm 12 has a left front end 18 opposite a left rear end 20, while the right suspension arm 14 has a right front end 22 opposite a right rear end 24.

[0033] The front ends 18, 22 of the two arms 12, 14 are equipped with a transversely extending bushing 26. The bushings 26 connect the two ends 18, 22 of the arms to the underside of the chassis of a motor vehicle. The two arms 12, 14 are pivotally mounted on the chassis at the rear of the vehicle by means of rubber bushings. The rubber bushings are engaged through the bushings 26 and they dampen vibrations from the arms.

[0034] On the opposite side, the rear ends 20, 24 of the two arms 12, 14 are equipped with wheel supports 28.

[0035] Also, the cross member 16 has two opposite ends, a left end 30 and a right end 32. And the two ends 30, 32 are notched in a "wolf's mouth" to form two seats adapted to receive respectively the two arms 12, 14. Thus, the two ends 30, 32 receive respectively an intermediate zone 34 of the two arms 12, 14, located approximately at two-thirds of the distance which extends from the rear ends 20, 24 to the corresponding front ends 18, 22.

[0036] Also, the arms 12, 14 are connected in T to the cross member 16 by means of weld beads applied to the joints between the two ends 30, 30 of the cross member 16 and respectively the intermediate areas 34 of the two arms 12, 14.

[0037] Thus, the intermediate zone 34 delimits, for the left arm 12 a rear left portion 36 extending from the intermediate zone 34 to the rear left end 20 and for the right arm 14, a rear right portion 38 extending from the intermediate zone 34 to the rear right end 24.

[0038] The rear left portion 36 and the rear right portion 38 form respectively with the cross member 16 a rear left angle 40 and a rear right angle 42.

[0039] The axle 10 comprises a left-hand cup 44 installed in the left rear corner 40 and a right-hand cup 46 installed in the right rear corner 42. The cups 44 and 46 are obtained by a stamping process from a metal plate. The metal plate has, for example, a thickness of between 1 mm and 3 mm. According to a particularly advantageous embodiment of the invention, the metal plate has a thickness of 2 mm.

[0040] The left cup 44 has a left front edge 48 welded to the cross member 16 and a left side edge 50 welded to the left rear portion 36 of the left arm 12. And oppositely, the right cup 46 has a right front edge 52 welded to the cross member 16 and a right side edge 54 welded to the right rear portion 38. The cups 44, 46 extend substantially in the mid-plane defined by the cross member 16 and the two suspension arms 12, 14.

[0041] Also, the left cup 44 has a free left lateral rim 56 opposite the left lateral rim 50 and a free left rear rim 58 opposite the left front rim 48. The two free rims 56, 58 are substantially perpendicular to each other and they meet to form a left arc 60. The left cup 44 also has a left upper face 65 opposite a left lower face 67.

[0042] Also, it will be observed that the free edges 56, 58 are upright relative to the lower left face 67. In this way, these upright free edges 56, 58 make it possible to increase the rigidity of the cup 44.

[0043] In contrast, the right cup 46 has a free right lateral rim 62 opposite the right lateral rim 54 and a free rear right rim 64 opposite the front right rim 52. The two free rims 62, 64 are substantially perpendicular and they meet to form a right circular arc 66. The right cup 46 has a straight upper face 68 opposite a straight lower face 70.

[0044] Similarly, the two free edges 62, 64 are raised relative to the lower right face 70 to increase the rigidity of the right cup 46.

[0045] The cups, left 44 and right 46, serve, on the one hand, to keep the cross member 16 and the two arms, left 12 and right 14, square, and on the other hand, to receive helical springs, not shown, bearing against their upper faces 65 and 68. The helical springs are axially compressible in a direction substantially perpendicular to the upper faces 65 and 68.

[0046] Furthermore, the cups exhibit a circular symmetry deformation forming a dome 75 and extending outward from said upper surface. In this way, the bases Springs bear axially against the upper faces 65, 68, around their dome 75. Consequently, the base of the springs in contact with the upper faces 65, 68 is blocked in translation along the planes defined respectively by the cups 44, 46.

[0047] Reference will now be made to [Fig. 2] and [Fig. 3] showing in detail, according to a first embodiment, the implementation of a left-hand cup 44' allowing the cross member 16' to be protected. Elements identical to those shown in [Fig. 1] and playing the same role will bear the same reference numeral with a prime sign: « ' ».

[0048] Reference will first be made to [Fig. 3] showing the single left-hand cup 44'. However, the right cup, according to this first variant execution, will have the same characteristics.

[0049] Thus, we find the upper face 65' of the cup 44' and the left front edge 48'. Beyond a plane Pp perpendicular to the upper face 65' and extending along the edge 48', the latter has a lateral extension 72 extending opposite the left lateral edge 50'. This lateral extension 72 increases the dimensions of the application surface 74'. The application surface 74' corresponds to the free edge of the edge 48' extended by its lateral extension 72.

[0050] Thus, the application surface 74' has dimensions greater than the cross-section of the cup 44' by the perpendicular plane Pp', which cross-section corresponds substantially to the application surface of the left cup 44 as illustrated in [Fig. 1]. The application surface 74' is therefore a function of the thickness of the cup and the length of the rim 48' extended by the lateral extension 72.

[0051] Thus, as illustrated in [Fig. 2], the application surface 74' against the cross member 16' is larger than that of the front edge 48 of the left cup 44 shown in [Fig. 1]. Also, the left front edge 48' is connected to the cross member 16' by means of weld beads that extend to the joint between the two.

[0052] Thus, when the axle 10' is stressed, and in particular when the rear left portion 36' tends to pivot relative to the cross member 16' by moving closer to it, the left cup 44' opposes this movement without the mounting surface 74' punching into the cross member 16'. This punching occurs particularly in the extension of the free left lateral edge 56', when the front edge 48' lacks a lateral extension 72.

[0053] Indeed, increasing the application area 74' allows for a reduction in the forces exerted per unit area on the cross member 16'.

[0054] Reference will now be made to [Fig.4] showing, according to a second embodiment, the increase in the application surface of the cup.

[0055] Elements identical to those shown in [Fig. 1] and playing the same role shall bear the same reference number with a double prime sign: « ” ”.

[0056] Figure 4 shows the left-hand cup 44" alone according to this second embodiment. However, according to this second embodiment, the right-hand cup also has the same characteristics.

[0057] Thus, we find the free left lateral edge 56” of the left cup 44”, in front of [Fig.4] and opposite it towards the rear, its left lateral edge 50”. We also find its upper face 65” opposite its lower face 67”.

[0058] And we find, the front left edge 48”, which is curved in the opposite direction to the upper face along generatrices parallel to the plane Pp”.

[0059] Thus, the curved front left edge 48" defines an application surface 74" which fits the surface of the cross member 16". In this way, a larger application surface is obtained than that obtained according to the prior art.

[0060] The 48” curved left edge is obviously welded to the 16” cross member at the joint between the two.

[0061] Thanks to the dimensions of the 74” application surface of the 44” left-hand cup according to this second embodiment, the same advantages are obtained as those obtained with the 44’ left-hand cup according to the first embodiment. In this way, the 16” cross member is protected from the punching effects of the 44” left-hand cup.

[0062] Furthermore, just as in the first embodiment, the right cup, not shown, has the same structural and functional characteristics as the left cup 44”.

Claims

Demands

1. Rear axle (10) of a motor vehicle comprising: - a pair of suspension arms (12, 14), each of the suspension arms having a front end (18, 22) adapted to be pivotally mounted on a vehicle chassis and a rear end (20, 24) receiving a wheel support (28); - a cross member (16) connecting the suspension arms (12, 14) in a T-junction in an intermediate zone (34) located between said front end and said rear end, said two arms (12, 14) each having a rear portion (36, 38) extending from said intermediate zone (34) to said rear end (36, 38) and forming two rear angles (40, 42) with said cross member (16); - two support cups (44, 46) mounted respectively in the said two rear corners (40, 42), each of the said cups having, on the one hand, an upper face (65, 67;68, 70) to be able to receive a spring in support, and on the other hand a front edge (48, 52) welded to said cross member (16) and a side edge (50, 54) welded to said rear portion (36, 38); characterized in that said front edge (48, 52) of said two cups (44, 46) has an application surface (74', 74") against said cross member (16), which is greater than the section of said two cups (44, 46) along a plane Pp extending perpendicularly to said upper face (65, 68) and along said front edge (48, 52); and in that each of said cups (44, 46) has a free rear edge (58, 64) opposite said front edge (48, 52) and a free lateral edge (56, 62) opposite said welded lateral edge (50, 54), said free edges joining together to form an arc of a circle (60, 66) and being curved opposite said upper face (65, 68).

2. Rear axle according to claim 1, characterized in that said front edge (48') has a lateral extension (72) such that said front edge (48') has a length greater than the length of said straight section.

3. Rear axle according to claim 2, characterized in that said front edge (48') extends opposite said side edge (50').

4. Rear axle according to claim 1, characterized in that said front edge (48”) is curved opposite said upper face (65') along generatrices parallel to said plane Pp to fit the surface of said cross member (16).

5. Rear axle according to any one of claims 1 to 4, characterized in that said cross member (16) is tubular.

6. Rear axle according to any one of claims 1 to 5, characterized in that each of said cups (44, 46) has a circular symmetry deformation (75) extending in projection from said upper surface (65, 68).

7. Motor vehicle comprising a rear axle (10) according to any one of claims 1 to 6.

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