Lower suspension arm

Abstract

The invention relates to a lower suspension arm comprising a flat, stamped metal part (20) having, on the one hand, two inclined arms (22, 24) defining an extrados (26), and an intermediate arm (54) projecting from said extrados opposite one (22) of said two arms, and having, on the other hand, two extrados edges (60, 62) extending into said extrados (26) converging towards each other to form a free U-shaped end (64), said free U-shaped end having two parallel notched edges (66, 68) joined by a projecting bottom edge (70). The arm further comprises another flat metal part (76) connected to said flat, stamped metal part (20). And said other flat metal piece (76) includes a tongue (114) extending in said intermediate branch (54) between said two converging rims (60, 62) to bear against said socket (122) opposite said projecting bottom rim (70).Figure to be published with the abbreviation: Fig. 6.

Description

Title of the invention: Lower suspension arm

[0001] The present invention relates to a lower suspension arm intended to be implemented in a front axle of a motor vehicle.

[0002] The lower suspension arms of a motor vehicle allow the two front wheels to be connected to the chassis of the vehicle.

[0003] Each of the lower arms usually comprises a flat stamped metal piece. This piece has two branches inclined to each other at an angle substantially greater than 90°, which two branches thus define an extrados opposite an intrados.

[0004] A first branch of said two branches has a first end connected to the chassis of the motor vehicle, while the second end of the second branch is connected to the wheel support.

[0005] Also, the flat metal piece has an intermediate branch which extends outward from the extrados in a direction opposite to the second branch joining the wheel support.

[0006] In addition, the stamping makes it possible to produce a rim in the intrados of the part and on the opposite side, two rims in the extrados, which two rims converge towards each other in the intermediate branch to form a free U-shaped end.

[0007] The free U-shaped end thus has two parallel edges connected by a perpendicular bottom edge. The two parallel edges are then notched, and the bottom edge extends substantially in projection. In this way, a sleeve can be welded, held against the two notched edges and against the projecting bottom edge.

[0008] To achieve this, portions of weld bead are provided between the sleeve and the contacting edges to secure the sleeve and the intermediate arm of the metal part. The axis of symmetry of the sleeve then extends substantially parallel to the average plane of the metal part and intersects the first end of the first arm connected to the chassis.

[0009] The first end has an orifice whose axis of symmetry is substantially perpendicular to the average plane of the metal part.

[0010] Thus, the lower arm is adapted to be installed on the chassis such that the socket of the intermediate arm is mounted to pivot in a direction parallel to the longitudinal direction of the vehicle, while the first end of the first arm is connected to the chassis along a vertical axis of the vehicle. The intermediate arm is hinged to the chassis, facing forward, while the first end of the first arm is mounted facing rearward.

[0011] Reference may be made to document EP 794 075, which describes such a lower suspension arm.

[0012] However, the lower arm and the bushing in particular are subjected to significant stress during the acceleration and braking phases of the motor vehicle.

[0013] Also, a problem which arises and which the present invention aims to solve is to provide a lower arm which is more resistant.

[0014] To this end, a lower front suspension arm for a motor vehicle is proposed, comprising a flat stamped metal part having on one hand two arms inclined relative to each other defining an extrados, and an intermediate arm extending outward from said extrados opposite one of said two arms, and having on the other hand two extrados rims extending into said extrados converging towards each other in said intermediate arm forming a free U-shaped end, said free U-shaped end having two parallel notched edges joined by a projecting bottom edge to allow a bushing to be welded in support in said two notched edges and against said projecting bottom edge.The arm further comprises another flat metal piece connected to said stamped flat metal piece; and said other flat metal piece comprises a tab extending in said intermediate branch between said two converging edges to bear against said socket opposite said projecting bottom edge.

[0015] Thus, a feature of the invention lies in the implementation of another metal piece equipped with a tab which can come to rest against the socket opposite the protruding bottom edge.

[0016] Said other metal piece shall be referred to as second metal plate while said metal plate shall be referred to as first metal plate in the rest of the description.

[0017] Thus, additional weld beads can be formed in the contact areas between the tab and the sleeve. In this way, the two metal parts and the sleeve become a single rigid piece.

[0018] This second metal piece is also welded to the first metal plate, thereby stiffening it. In this way, the connection between the sleeve and the first metal piece is strengthened, and, moreover, the resistance of the first metal piece to deformation is increased, as will be explained below.

[0019] According to a particularly advantageous embodiment of the invention, said tab has a cylindrical shape of revolution to be applied against said sleeve. The tab is thus defined as a fraction of a cylinder of revolution which then conforms to the external shape of the sleeve. Consequently, two weld beads Parallel arcs can be created between the two opposite edges of the tongue and the socket. This strengthens the connection between the socket and the second metal piece.

[0020] Furthermore, said tab preferably has an oblong slot. The oblong slot extends substantially equidistant from the two opposite edges of the tab in the cylindrical portion. In this way, it is possible to add a central weld bead through the oblong slot and further secure the tab and the socket.

[0021] Furthermore, said tongue advantageously has a longitudinal rib. The longitudinal rib extends, for example, upstream of the oblong opening and thus stiffens the tongue. This longitudinal rib is, for example, produced during the stamping of the second metal part.

[0022] Moreover, the tab is welded to the sleeve and to the two converging edges in the intermediate branch. In other words, the two complementary weld beads extending along the two opposite edges of the tab can be continued and extended to the joint between the tab and the two converging edges. In this way, the assembly formed by the tab, the intermediate branch, and the sleeve is further stiffened.

[0023] According to a particularly advantageous feature of the invention, said other flat metal piece comprises two other branches inclined relative to each other, defining another extrados, and another intermediate branch extending in projection from said other extrados opposite one of said two other branches, said other intermediate branch being extended by said tongue.

[0024] Thus, the second metal part has a general shape similar to the first metal part and can be pressed against it in predefined contact areas, as will be explained below. In this way, the lower suspension arm exhibits a significantly higher intrinsic mechanical resistance to deformation compared to an arm made from a single metal plate.

[0025] Furthermore, said other flat metal part advantageously comprises two upper surface edges converging towards each other in said other intermediate branch, and said two upper surface edges join said two upper surface edges. In this way, the two upper surface edges of the second metal part come into contact respectively and without discontinuity against the two upper surface edges of the first metal part, and can be joined thereto by two weld beads, which can then respectively join the extensions of the two complementary weld beads. Thus, the other upper surface of the second metal part is completely joined to the upper surface of the first metal part.

[0026] Also, the two inclined branches define an intrados opposite the extrados, and the stamped flat metal part has an intrados rim extending opposite the extrados rims. In this way, the first stamped flat metal part is mechanically reinforced not only on its extrados, but also on its intrados. It is thus formed in volume by defining an inner base opposite which the second metal part extends.

[0027] Moreover, the two other inclined arms define another intrados opposite the other extrados, and the other flat metal piece has an intrados edge adapted to join the intrados rim. In this way, the second metal piece can be fitted between the intrados rim and the two extrados rims of the first metal piece, where it is held in place and welded along its edges. Furthermore, the second metal piece is advantageously kept away from the bottom of the first metal piece, except at the ends of its two arms. In this way, a lower suspension arm is obtained that is much more resistant to deformation under stress than an arm made from a single stamped metal plate.

[0028] Also, the two parallel notched edges are respectively cut along a line having a constant radius of curvature. Advantageously, this constant radius of curvature corresponds to the external radius of the sleeve. In this way, the two notched edges are continuously in contact with the external surface of the sleeve. The weld beads extending circularly at the joint between the notched edges and the sleeve thus provide a better bond.

[0029] Other features and advantages of the invention will become apparent from the following description of a particular embodiment of the invention, given by way of example but not limitation, with reference to the accompanying drawings in which:

[0030] [Fig.1] is a partial schematic top view of a motor vehicle equipped with the object of the invention;

[0031] [Fig.2] is a partial schematic top perspective view of an element of the object of the invention;

[0032] [Fig.3] is a partial schematic top perspective view of another element of the object of the invention adapted to cooperate with that shown in [Fig.2];

[0033] [Fig.4] is a schematic perspective detail view of the assembly of the objects [Fig.2] and [Fig.3];

[0034] [Fig.5] is a schematic perspective view of the object of [Fig.4] and yet another another element;

[0035] [Fig.6] is a schematic view from below of the object of the invention illustrated in the [Fig. 1]; and,

[0036] [Fig.7] is a schematic detail view of the object of [Fig.6].

[0037] Fig. 1 partially shows the front left top of a motor vehicle 10, and it is inscribed in an orthogonal coordinate system X, Y, Z, in which the X axis extends along a longitudinal front-to-rear direction of the motor vehicle, oriented towards the rear; the Y axis extends along a transverse direction of the vehicle, oriented from left to right when in a driving situation; and the Z axis extends along a vertical direction, oriented away from the ground.

[0038] Figure 1 shows a chassis element 12 and a body element 14 of the motor vehicle. The chassis element 12 receives a left front lower suspension arm 16, which connects a left front wheel 18 to the chassis element 12. A right front lower suspension arm (not shown), symmetrical to the left lower suspension arm with respect to a median plane of the motor vehicle, also connects a right front wheel to another chassis element (not shown).

[0039] The lower suspension arm 16 has, in top view, a first flat stamped metal piece 20 which can be seen in detail in the [Fig.2] top view according to arrow II.

[0040] It comprises two branches inclined relative to each other, a first first branch 22 and a second first branch 24. The two first branches 22, 24 thus inclined define a first extrados 26 and on the opposite side, a first intrados 28.

[0041] Also, the first first branch 22 has a first first fixing end 30 having three first fixing holes, a first central hole 32 and two first lateral holes 34, 36. The second first branch 24 has a second first end 38 having a circular recess 40.

[0042] Also, the first first branch 22 has a first first median longitudinal deformation 42 corresponding to a depression, while the second first branch 24 has a second first median longitudinal deformation 44 joining the first first median deformation 42. The first first median deformation 42 gives rise to two lateral ribs, a first first rib 46, on the side of the first intrados 28 and a second first rib 48, on the side of the first extrados 26. As for the second first median deformation 44, it gives rise to a first second rib 50 on the side of the first intrados 28 and, on the opposite side, a second second rib 52 on the side of the first extrados 26.

[0043] These deformations 42, 44 are carried out during the stamping of the metal part.

[0044] Furthermore, the first metal part 20 has a first branch intermediate 54 extending in the continuation of the first first branch 22, opposite the first first attachment end 30 and projecting from the first extrados 26.

[0045] Also, on the extrados side 26, the first first branch 22 has a first edge 56, while the second first branch 24 has a second edge 58. And the two edges 56, 58 are folded during the stamping to form respectively a first rim 60 and a second rim 62. The two rims 60, 62 then converge towards each other in the first intermediate branch 54 forming a free U-shaped end 64.

[0046] The free U-shaped end 64 thus has two parallel notched edges 66, 68 defining the same radius of curvature, and a bottom edge 70 connecting the two notched edges 66, 68. The bottom edge 70 extends in projection, and it has two lateral notches 72, 74. The free U-shaped end 64 thus forms a "wolf's mouth" structure suitable for receiving a cylindrical element of revolution as will be explained in more detail below.

[0047] Furthermore, on the side of the first intrados 28, the first two branches 22, 24 have a first continuous edge 75 folded to form a first continuous rim 78. The first continuous rim 78 then extends partly opposite the first 60 and second 62 rims, defining a receiving space 80 delimited by a bottom 81. The bottom 81 corresponds to the internal surface of the first stamped metal part 20.

[0048] Reference will now be made to [Fig.3] illustrating a second flat stamped metal piece 76 adapted to cooperate with the first metal piece 20 as will be explained in the rest of the description.

[0049] It comprises two second branches inclined relative to each other, a first second branch 82 and a second second branch 84. The two inclined second branches 82, 84 also define a second extrados 86 and, opposite, a second intrados 88.

[0050] Also, the first second branch 82 has a first second fixing end 90 having three second fixing holes, a second central hole 92 and two second lateral holes 94, 96. The second second branch 84 has a second second end 98.

[0051] Also, the first second branch 82 has a first second median longitudinal deformation 102 corresponding to a sinking, while the second second branch 84 has a second second median longitudinal deformation 103 joining the first second median deformation 102.

[0052] In addition, the second metal piece 76 has a second intermediate branch 104 extending in line with the first second branch 82, opposite the first second fixing end 90 and projecting from the second extrados 86.

[0053] Also, on the side of the second extrados 86, the first second branch 82 has a first edge 106, while the second second branch 84 has a second edge 108.

[0054] And the two edges 106, 108 converge towards each other in the second intermediate branch 104, forming the two substantially parallel opposite edges 110, 112 of a tongue 114. The tongue 114 terminates with a free edge 115 connecting its two parallel edges 110, 112.

[0055] The tongue 114 has a cylindrical shape of revolution. The radius of curvature of the tongue 114 is then identical to that of the two notched edges 66, 68.

[0056] Also, the tab 114 has an oblong slot 116, and the intermediate branch 104 has a reinforcing rib 118 located upstream of the oblong slot 116 and extending from it. The reinforcing rib 118 is intended to stiffen the second intermediate branch 54. The role of the oblong slot 116 will be explained below.

[0057] Furthermore, on the side of the second intrados 88, the two second branches 82, 84 have a continuous edge 120 extending continuously from the first second end of attachment 90 to the second second end 98.

[0058] Also, the geometry of the second metal piece 76 is identical to that of the first piece 20 so as to be able to fit it inside the receiving space 80 and to support it in certain areas of the bottom 81 of the first piece 20.

[0059] And in particular, the second intermediate branch 104 and the tongue 114 which it extends, will then come to engage in the first intermediate branch 54 between the two rims 60, 62 by crossing the free end in U 64, as illustrated in detail on the [Fig.4].

[0060] The tongue 114 is then adjusted so that its internal surface comes at least partially to the flushness of the two notched edges 66, 68, and that its free edge 115 comes to extend opposite the bottom edge 70 of the free end U 64.

[0061] We also find on [Fig.4] the oblong light 116 of the tongue 114.

[0062] Thus, such an arrangement of the two stamped metal parts 20, 76 one in the other and in particular the adjustment of the tab 114 of the free end in U 64, allows to accommodate a socket 122 as illustrated in [Fig.5].

[0063] The sleeve 122 has cylindrical symmetry of revolution and its external diameter coincides both with the radius of curvature of the two notched edges 66, 68 here masked by the sleeve 122, and with that of the tongue 114.

[0064] In this way, the socket 122 is in contact with the internal cylindrical surface of the tongue 114, with the two notched edges 66, 68, and with the bottom part of the first piece 22 located inset from the bottom edge 70.

[0065] Reference will now be made to [Fig.6] and [Fig.7] illustrating the method of joining by welding, both of the two metal parts 20, 76 and also of the sleeve.

[0066] Thus, on [Fig.6], seen from below, we find the second metal piece 76 embedded in the first metal piece 20. We will observe that the continuous edge 120, on the side of the second intrados 88 of the second piece 76, applies itself against the first continuous rim 78 of the first intrados 28 of the first piece 20.

[0067] And on the opposite side, on the side of the second extrados 86, the first edge 106 of the first second branch 82 is applied against the first rim 60, while the second edge 108 is applied against the second rim 62.

[0068] Consequently, the second piece 76 is totally captive of the first piece 20 in the average plane defined by the first piece.

[0069] Moreover, only the first second end of the fixing 90 and second second end 98 of the second part 76 are supported in the bottom 81 of the first part 20, while the tongue 114 is supported on the socket 122.

[0070] In the other areas of the second part 76, the two parts 76, 20 are separated from each other.

[0071] Once thus fitted, the metal parts 20, 76 and the bushing 122 are welded together by means of a plurality of weld beads. On the intrados side 28, 88, a first continuous weld bead 124 connects the first continuous rim 78 and the continuous rim 120.

[0072] On the extrados side 26, 86, a second continuous weld bead 126 connects together the first edge 106 and the first rim 60, while a third continuous weld bead 128 connects together the second edge 108 and the second rim 62.

[0073] At the level of the sleeve 122, firstly, the second continuous weld bead 126 extends, along a first circular segment 130 between the tab 114 and the first rim 60, and it continues along a second circular segment 132, between the sleeve 122 and the edge 110 of the tab 114.

[0074] Next, the third continuous weld bead 128 extends itself, along a first second circular segment 134 between the tab 114 and the second rim 62, and it continues along a second second circular segment 136 between the sleeve 122 and the other rim 112 of the tab 114.

[0075] In addition, an intermediate portion of a circular weld segment 138 is brought through the oblong opening 116 straddling the tab 114 and the socket 122.

[0076] We thus find on [Fig.7], opposite to [Fig.6], the sleeve 122 and the two second circular segments 132, 136 of weld bead between the sleeve 122 and the two opposite edges 110, 112 of tongue 114.

[0077] Furthermore, at the level of the two lateral notches 72, 74 and the two notched edges 66, 68, two lateral portions of weld bead 140, 142 symmetrical to each other are respectively attached astride the sleeve 122.

[0078] In this way, a perfect bonding of the two stamped metal parts 22, 76 together is obtained, and in addition, a perfect bonding of the sleeve 122 with these two parts 22, 76. This better bonding, compared to the prior art, is in particular linked to the implementation of the tab 114, welded to the sleeve 122, which then partially envelops the latter by forming a vise with the part of the first intermediate branch 54 which is extended by the bottom edge 70.

Claims

Demands

1. Lower front suspension arm of a motor vehicle comprising a flat stamped metal part (20) having on one hand two arms (22, 24) inclined relative to each other defining an extrados (26), and an intermediate arm (54) extending projecting from said extrados opposite one (22) of said two arms, and having on the other hand two extrados rims (60, 62) extending in said extrados (26) converging towards each other in said intermediate arm forming a free U-shaped end (64), said free U-shaped end having two parallel notched edges (66, 68) joined by a projecting bottom edge (70) for welding a bushing (122) bearing in said two notched edges and said projecting bottom edge; characterized in that it further comprises another flat metal piece (76) connected to said stamped flat metal piece (20);and in that said other flat metal piece (76) comprises a tab having an oblong opening (116) and (114) extending in said intermediate branch (54) between said two converging edges (60, 62) to bear against said socket (122) opposite said projecting bottom edge (70).;

2. Arm according to claim 1, characterized in that said tongue (114) has a cylindrical shape of revolution to come into contact with said socket (122).

3. Arm according to claim 1 or 2, characterized in that said tongue (114) has a longitudinal rib (118).

4. Arm according to any one of claims 1 to 3, characterized in that said tongue (114) is welded to said bushing (122) and to said two flanges (60, 62) converging in said intermediate arm (54).

5. Arm according to any one of claims 1 to 4, characterized in that said other flat metal piece (76) has two other branches (82, 84) inclined relative to each other defining another extrados (86), and another intermediate branch (104) projecting out of said other extrados (86) opposite one (82) of said two other branches, said other intermediate branch (104) being extended by said tongue (114).

6. Arm according to claim 5, characterized in that said other flat metal piece (76) has two extrados edges (106, 108) converging towards each other in said other intermediate branch (104), and in that said two extrados edges (106, 108) join said two extrados edges (56, 58).

7. Arm according to any one of claims 1 to 6, characterized in that said two inclined arms (22, 24) define an intrados (28) opposite said extrados (26), and in that said stamped flat metal piece (20) has an intrados rim (78) extending opposite said extrados rims (56, 58).

8. Arm according to claims 6 and 7, characterized in that said two other inclined arms (82, 84) define another intrados (88) opposite said other extrados (86), and in that said other flat metal piece (76) has an intrados edge (120) adapted to join said intrados edge (78).

9. Arm according to any one of claims 1 to 8, characterized in that said two parallel notched edges (66, 68) are respectively cut along a line having a constant radius of curvature.

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