MOTOR VEHICLE WHEEL HAVING AN ALUMINIUM RIM AND A STEEL WHEEL DISC JOINED TOGETHER BY WELDED PINS

Abstract

The invention relates to a wheel intended for a motor vehicle, having a rim (2) made of a sheet of aluminium alloy that is fastened to the contour of a wheel disc (10) made from a steel sheet by assemblies that connect the aluminium, sheet of the rim and the steel sheet of the wheel disc, which overlap one another, the assemblies comprising connecting pins (20) that have a tip that passes through a hole in the aluminium sheet of the rim (2), the front end of which is welded to the steel sheet of the wheel disc (10), and a rear head that presses against the aluminium sheet of the rim about said hole.

Claims

1. A wheel intended for a motor vehicle, the wheel comprising a rim made of an aluminum alloy sheet, fixed to the perimeter of a disc made of a steel sheet by assemblies that connect the aluminum sheet of the rim to the steel sheet of the disc, which are superimposed, wherein the assemblies comprise connecting pins that have a tip that passes through a hole in the aluminum sheet of the rim, a front end of the tip being welded to the steel sheet of the disc, and a rear head of the tip bearing on the aluminum sheet around this hole.

2. The wheel according to claim 1, wherein the head of the pins has indentations around its contour perimeter enabling it to be driven in rotation.

3. The wheel according to claim 2, wherein the indentations have shapes enabling driving by a tool in one direction of rotation only.

4. The wheel according to claim 1, wherein the end of the pin tips is domed.

5. The wheel according to claim 1, wherein the aluminum sheet forms around the pin tip a circular beading protruding above this sheet.

6. The wheel according to claim 5, wherein the pin head has beneath it an annular hollow into which the circular beading fits.

7. The wheel according to claim 1, wherein the wheel comprises assemblies each being formed by a pair of pins positioned close together, these assemblies being distributed evenly around the perimeter of the wheel.

8. The wheel according to claim 1, wherein the aluminum sheet of the rim receiving the fixing of the disc forms a cylindrical rim base having the smallest diameter of the rim.

9. A method for manufacturing a wheel for a motor vehicle, the wheel comprising a rim made of an aluminum alloy sheet fixed round the perimeter of a disc made of a steel sheet by assemblies connecting the two superimposed sheets, wherein, with a cycle comprising different pressures and speeds of rotation of a steel pin, in a first step a front tip of this pin is pressed onto the aluminum sheet in order to pierce this sheet, in a subsequent step a front tip of the pin is pressed onto the steel sheet of the disc in order to cause a plastic deformation of this sheet adapting to the end shape of this tip, and in a subsequent step the tip of the pin is friction-welded onto the steel sheet of the disc.

10. A motor vehicle comprising wheels of claim 1.

Description

DESCRIPTION OF THE FIGURES

[0028] Further features and advantages of the invention will emerge more clearly from the following description, given by way of example, with reference to the accompanying drawings in which:

[0029] FIG. 1 shows successively a wheel assembled, then the detail of the rim and disc of this wheel;

[0030] FIGS. 2 and 3 show side and front views, respectively, of the wheel;

[0031] FIG. 4 shows a cross-sectional view of this wheel taken along line IV-IV of FIG. 3;

[0032] FIG. 5 shows an assembly pin of this wheel; and

[0033] FIG. 6 is a detailed sectional view of the assembly of this wheel taken along line VI-VI of FIG. 4.

DETAILED DESCRIPTION

[0034] FIG. 1 shows a wheel comprising a rim 2 formed from an aluminum sheet, having a circular profile comprising two lateral edges 6 intended to frame a tire. The rim 2 has, between the two edges 6, a rim base 4 forming the cylindrical part having the smallest diameter.

[0035] A disc 10 formed from a steel sheet has a central locating hole 12 surrounded by four holes 14 intended to receive studs for fixing the wheel onto the vehicle's hub.

[0036] Towards the outside, the disc 10 has a series of weight-reducing holes 16, then the sheet has an external perimeter 18 forming a cylindrical part facing towards the vehicle, intended to fit by clamping into the rim base 4 of the rim 2 in order to center this rim.

[0037] FIGS. 2, 3 and 4 show the disc 10 held fixed in the rim 2 by four assemblies comprising a pair of pins 20, evenly distributed round the wheel in the same transverse plane, each comprising two pins arranged closely together.

[0038] FIG. 5 shows in detail a steel pin 20 comprising a tip 38 terminating below in a domed shape and a head 30, the flat top of which has around its perimeter a tapered chamfer 32.

[0039] The perimeter of the pin head 30 comprises six indentations 34 each forming a downward inclined facet, which terminates in the clockwise direction of rotation in a perpendicular face 36 arranged in an axial plane. In this way, a tool having a shape corresponding to the indentations 34 can drive the pin 20 in rotation in a clockwise direction, with reference to FIG. 5, by bearing on the perpendicular faces 36.

[0040] Conversely, a rotation of the tool in the opposite direction does not drive the pin 20. In this way, an arrival of the tool on the head of the pin 30 and a start of rotation easily positions the notches of this tool in the indentations 34.

[0041] FIG. 6 shows a pair of pins 20 each comprising a tip 38 that passes through the aluminum sheet of the rim base 4, the end of the tip being fitted into and welded in a corresponding hollow formed in a boss 40 of the disc contour 18.

[0042] The pin head 30 constitutes a collar bearing on a circular beading 42 formed above the rim base 4, which surrounds the tip 38 of the pin 20, and fits into an annular hollow formed beneath this head.

[0043] The pin 20 is installed as follows. In a first step with a press encompassing the two superimposed sheets of the rim base 4 and the disc perimeter 18, a strong pressure is applied on the pin 20 and, using the cut-outs 34, the pin is rotated, so as to pierce with its tip 30 the aluminum alloy sheet of the rim base 4. This piercing causes an upward displacement of the material of the rim base 4, forming the circular beading 42 around the tip 38 of the pin.

[0044] In a second step, a rotation of the pin 20 applies a pressure of the end of its tip 38 on the steel disc contour 18 in order to clean and activate these two surfaces in contact.

[0045] In a third step, the rotation of the pin 20 continues, causing a plastic deformation of the sheet of the disc contour 18, which forms a corresponding hollow at the domed end of the tip 38 of this pin, and around the boss 40 by displacement of material.

[0046] In a fourth step the pin 20 is rotated at a high pressure so as to achieve considerable heating of the end of the pin and of the sheet of the disc perimeter 18 in contact, and a weld joint between these elements. At the same time, the final descent of the pin 20 causes a shaping of the circular beading 42 of the rim base 4, which fits into the annular hollow formed above the head 30 of this pin.

[0047] In this way, an effective clamping of the rim base 4 on the sheet of the disc contour 18 is achieved by the axial clamping of the pin head 30 on the circular beading 42 of this rim.

[0048] It will be noted that this fixing method is simple and quick to implement, does not require prior pilot drilling of the rim 2 or prior- or post-treatment of the sheets after this operation. In practice, each pin placement is performed in a single operation, by a press comprising a cycle of pressures and speeds of rotation automatically performing the different steps of the method. A safe fixing necessary for wheels is thus achieved in an economic way.

[0049] For a 16-inch wheel with an aluminum alloy rim, a saving of around 1.3 kg per wheel is achieved, which equates to 5.2 kg for the entire vehicle. This reduction in vehicle weight contributes to a reduction in fuel consumption and emissions of polluting gases.

[0050] With this same method it is possible to assemble sheets of different thicknesses. In particular, for a small-diameter wheel, a minimum of three pins 20 arranged in a triangle can be fitted in order to ensure the connection between the disc and the rim.