Motor vehicle wheel having an aluminum rim and a steel wheel disc joined together by welded pins

Abstract

A wheel intended for a motor vehicle includes a rim made of a sheet of aluminium alloy that is fastened to the contour of a wheel disc 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 include connecting pins each of which has a tip that passes through a hole in the aluminium sheet of the rim, the front end of which is welded to the steel sheet of the wheel disc, 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, a disc made of a steel sheet sized to be received within the rim, and pins connecting the rim to the disc, the pins comprising a head and a tip extending from said head wherein the rim defines holes through which said tips of said pins pass to engage said disc, a front end of the tip being welded to the disc, and the head of the pin engaging the rim around the hole on a surface of the rim opposite the disc.

2. The wheel according to claim 1, wherein the head of each pin defines a contoured perimeter shaped to enable the pin to be driven in rotation.

3. The wheel according to claim 2, wherein the contoured perimeter of the pin head is shaped such that the pin can be driven by a tool in only one direction of rotation.

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

5. The wheel according to claim 1, wherein the rim forms a circular bead around the pin tip, the circular bead protruding above the rim.

6. The wheel according to claim 5, wherein the pin head defines an annular hollow on an underside of the pin head into which the circular beading fits.

7. The wheel according to claim 1, wherein the wheel comprises pin assemblies, each pin assembly comprising a pair of pins positioned proximate each other, the pin assemblies being distributed evenly around the perimeter of the wheel.

8. The wheel according to claim 1, wherein the rim defines a cylindrical rim base, the rim base defining a 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 to a perimeter of a disc made of a steel sheet by connecting pins, wherein, with a cycle comprising different pressures and speeds of rotation of a steel pin, the method comprising: a first step of pressing a front tip of the pin into the aluminum rim in order to pierce the aluminum rim, a subsequent step, pressing the front tip of the pin into the steel disc in order to cause a plastic deformation of the steel disc adapting to the shape of the end of the tip, and in a subsequent step friction-welding the tip of the pin to the steel sheet of the disc.

10. A motor vehicle comprising wheels of claim 1.

Description

DESCRIPTION OF THE FIGURES

(1) 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:

(2) FIG. 1 shows successively a wheel assembled, then the detail of the rim and disc of this wheel;

(3) FIGS. 2 and 3 show side and front views, respectively, of the wheel;

(4) FIG. 4 shows a cross-sectional view of this wheel taken along line IV-IV of FIG. 3;

(5) FIG. 5 shows an assembly pin of this wheel; and

(6) FIG. 6 is a detailed sectional view of the assembly of this wheel taken along line VI-VI of FIG. 4.

DETAILED DESCRIPTION

(7) 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.

(8) 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.

(9) 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.

(10) 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.

(11) 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.

(12) 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.

(13) 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.

(14) 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 perimeter 18.

(15) 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.

(16) 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.

(17) In a second step, a rotation of the pin 20 applies a pressure of the end of the tip 38 on the perimeter 18 of the steel disc 10 in order to clean and activate these two contacting surfaces.

(18) In a third step, the rotation of the pin 20 continues, causing a plastic deformation of the perimeter 18 of the steel disc, 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.

(19) 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 perimeter 18 of the steel disc at the point of contact to thereby form a weld joint between these elements (i.e., between the pin and the steel disc). At the same time, the final descent of the pin 20 causes a shaping of the circular bead 42 of the rim base 4, the bead 42 fitting into the annular hollow in the head 30 of this pin.

(20) In this way, an effective clamping of the rim base 4 on the sheet of the perimeter 18 of the steel disc is achieved by the axial clamping of the pin head 30 on the circular beading 42 of the rim 2.

(21) 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.

(22) 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.

(23) 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.