GB2028181A - Making steering wheels - Google Patents

Abstract

A steering wheel is constituted by a tubular rim (of aluminium) (1) defining two ends (2) into which are respectively fitted the ends (3) of two (steel) spokes, the assembly of the spokes (4) and the rim (1) being obtained by a simultaneous bending, e.g. until a substantially right angle is obtained, of the ends (2) of the rim (1) together with the ends (3) of each spoke (4) fitted therein, the said bending being accompanied by a concomitant interlocking compression of the said ends. <IMAGE>

Description

SPECIFICATION Improvements in or relating to a method of manufacturing vehicle steering wheel and steering wheel thus obtained The present invention relates generally to steering wheels for any types of automotive vehicles.

It relates more particularly to a new method of manufacturing a steering wheel and a steering wheel obtained by the said method.

In designing steering wheels for modern road vehicles two types of constraints have to be overcome: (1) In the first place, the vertical vibration of the steering columns and wheel assembly.

As in known, the various forces to which the body of a motor-car is subjected result in vibrations of the steering wheel along its axis and in its vertical plane. These are low-frequency vibrations that are generally produced when the vehicle is running on a bad road and that arise directly from the wheel suspension reactions and the engine movements which result therefrom and are transmitted by the engine suspension shims or blocks.

In addition, the vertical natural frequency of the steering wheel is unfortunately within a range of rather small values. This is largely due to the steering wheel overhang with respect to the structure on which it is mounted.

Indeed, the increasingly used single-spoked steering wheel technique and the small diameter which is given to the steering wheel are among the particular factors promoting the vibration of the steering wheel at a relatively low frequency.

(2) A second constraint encountered in designing steering wheels resides in the inertia of the steering wheel in rotation.

It is known that the polar inertia of the wheel, considering the reduction in the steering gear box, has to be taken into account in dealing with the problem of dynamic sway stability. Indeed, this mass connected to the steering is such as to reduce the frequency of the free sway oscillations and therefore to reduce the speed of the vehicle in use beyond which the said sway oscillations diverge and become dangerous for the user.

Thus, in the case of an overloaded vehicle, or of one drawing a highly loaded trailer, not seldom is the user hindered in controlling the trajectory of his vehicle, even to the point of completely losing control of the vehicle in case of sudden handling. Now experience shows that it is desirable to reduce the steering wheel mass so as to obviate the abovementioned cases of instability.

The purpose of the present invention is essentially to overcome both said constraints by providing a new steering wheel of substantially reduced mass without prejudicing its rigidity.

To this end, the invention is directed to a method of manufacturing a vehicle steering wheel constituted essentially by a tubular rim in the shape of a circular ring segment defining two ends into which are respectively fitted or inserted the ends of two substantially radial spokes or the like attached by their ends to a central hub, the said method being characterized by a simultaneous bending of each rim end together with the corresponding spoke end fitted therein, accompanied by a concomitant interlocking compression.

There is thus obtained a continuous and therefore perfectly rigid connection between the rim and the spokes.

According to another characterizing feature of the method of the invention, the bending operation, performed for example by rolling, is effected until a substantially right angle is obtained.

The invention is also directed to a vehicle steering wheel obtained by the above method and characterized essentially in that the fit-in portion or region of each spoke and of the rim is curved substantially at right angles.

According to another characterizing feature of the steering wheel of the invention, the said spokes, at least the said fit-in portion of which is of circular and preferably solid crosssection, are of steel, whereas the tubular rim is of a completely different metal, such as for example aluminium.

Thus, owing to the continuous and rigid connection between the rim and the spokes, as mentioned previously, the said rim and spokes may advantageously be made of alto- gether different materials allowing the weight of the steering wheel to be considerably reduced.

According to another characterizing feature of the invention, the rim is completed by a connecting element embracing at least partially each spoke, the said element being secured, for example welded, on each spoke.

According to another form of embodiment, the continuity of the rim is ensured by a connecting element directly secured, for example welded, on the said fit-in portion or region.

The invention is also directed to an automotive vehicle equipped with a steering wheel having the above-mentioned characterizing features.

Other features and advantages of the invention will appear more clearly from the following detailed description made with reference to the appended drawings given solely by way of example and wherein: Figure 1 is a top view, with parts broken away, illustrating a first form of embodiment of the steering wheel according to the invention; Figure 2 is a cross-sectional view through the axis of the steering wheel in the midperpendicular plane of the two steering wheel spokes, as indicated by the arrows ll-ll in Fig.

1; Figure 3 is an enlarged view of a spoke fitted into the steering wheel rim, according to the principle of the invention, and as shown to a smaller scale in the encircled portion III of Fig. 1; Figure 4 is a partial top view illustrating another form of embodiment of the steering wheel according to the principles of the invention; and Figure 5 is a cross-sectional view substantially upon the line V-V of Fig. 4.

According to one example of embodiment and referring more particularly to Figs. 1 and 4, a vehicle steering wheel according to the invention comprises essentially a tubular rim 1 in the shape of a circular ring segment defining two ends 2 into which are respectively fitted the ends 3 of two spokes or the like 4 secured by their ends 5 to a central hub 6.

According to the invention and as seen more clearly in Fig. 3, the spokes 4 are secured to the rim 1 by simultaneously bending each end 2 of the rim 1 with the corresponding end 3, of each spoke 4 fitted therein, the said bending being accompanied by a concomitant interlocking compression or sinking as seen clearly at la in Figs. 1, 2 and 3.

The said bending operation can be performed by rolling or the like. This operation is performed until a substantially right angle is obtained. It is important, here, to lay stress on the fact that the fit-in portion or region constituted by the ends 3 of each spoke 4 fitted into the rim 1 is curved substantially at right angles, thus ensuring a rigid assembly and allowing altogether different materials to be used for the substantially radial spokes 4 and the rim 1, as will be described hereafter.

According to the invention, the spokes 4 are preferably of circular cross-section and constituted by a steel wire, whereas the tubular rim 1 is of a quite different metal, e.g.

aluminium. It will be added here that the steel-aluminium assembly constituted by the radial spokes 4 and the rim 1 is particularly strong as a result of the bending and the concomitant locking compression of the ends 2 and 3, as appears clearly in the Figs.

Furthermore, the Applicant has found that such as assembly offers excellent fatigue resistance, high elastic limit as well as good weldability of the spokes 4 to the hub 6.

It will also be noted that the said bending operation by way of rolling can be so performed as to impart at the same time to the spokes 4 an appropriate shape converging towards the hub 6. Furthermore, as regards the rim 1, a hardening or tempering operation can be performed if the material constituting the rim is in the annealed state.

According to the form of embodiment illustrated in Figs. 1 and 2, the continuity of the rim 1 is ensured by a connecting element 7 which, as seen clearly, embraces at least partially each spoke 4. The embracing portion of the element 7 is welded at 9 on each spoke 4, as seen more clearly in Fig. 3.

According to a second form of embodiment and as appears in Figs. 4 and 5, the continuity of the rim 1 can be obtained by means of a connecting element 8 directly welded on the aforesaid fit-in portion.

As in known, the rim 1 as well as the connecting element 7 or 8 may advantageously be coated with an appropriate lining or the like, and, as seen better in Figs. 2 and 5, the steering wheel, after being placed on the hub 6, will appear as being mounted much forward of the said hub.

There is thus obtained, according to the invention, a steering wheel of composite structure, the essential constituent elements of which, i.e. the tubular rim of aluminium and the steel spokes, are assembled together very rigidly while at the same time using altogether different materials.

Such a steering wheel offers the user a feeling of pleasant and altogether safe steering, due to the fact that the vertical frequency of the vibrations imparted to the said steering wheel is equal to or higher than 40 cps.

Of course, the invention is by no means limited to the forms of embodiment described and illustrated which have been given by way of example only. In particular, it comprises all means constituting technical equivalents to the means described as well as their combinations should the latter be carried out according to its gist and used within the scope of the following claims.

Claims (9)

1. A method of manufacturing a vehicle steering wheel constituted essentially by a tubular rim in the shape of a circular ring segment defining two ends into which are respectively fitted the ends of two substantially radial spokes or the like secured by their ends to a central hub, characterized by a simultaneous bending of each rim end together with the corresponding spoke end fitted therein, accompanied by a concomitant interlocking compression.

2. A method according to claim 1, characterized in that the said bending, performed for example by rolling, is effected until a substantially right angle is obtained.

3. A vehicle steering wheel obtained by the method according to claim 1 or 2, of the type comprising a tubular rim in the shape of a circular ring segment defining two ends into which are respectively fitted two substantially radial spokes converging towards a central hub on the front of which they are secured, characterized in that the fit-in portion or region of each spoke and of the rim is curved substantially at right angles.

4. A steering wheel according to claim 3, characterized in that the said spokes, at least the said fit-in portion of which is of circular and preferably solid cross-section, are of steel, whereas the said tubular rim is of a completely different metal such as for example aluminium.

5. A steering wheel according to claim 3 or 4, characterized in that the continuity of the said rim is ensured by a connecting element embracing at least partially each spoke and welded on each spoke by its embracing portion.

6. A steering wheel according to claim 3 or 4, characterized in that the continuity of the said rim is ensured by a connecting element secured, e.g. welded, directly on the said fit-in portion.

7. An automotive vehicle equipped with a steering wheel according to one of claims 3 to 6.

8. A method substantially as described herein.

9. A steering wheel substantially as described herein with reference to and as shown in the accompanying drawings.