Motor vehicles steering wheel and relative procedure for its realisation

Abstract: Steering wheel comprising a driving rim (1) consisting of an internal polyurethane core (3), covered at least partially with a coating of a material with an aesthetically finer quality (15). Said steering wheel is realised starting form a driving rim (1) with a polyurethane core (3) by means of a procedure comprising the following phases: grinding of the surface of said polyurethane core (3), realisation of a couple of coating elements of material with aesthetically finer quality (15) having plane shape and size congruent to at least one portion of said polyurethane core (3), application of said coating elements (15) to said polyurethane core and respective bending of the same by means of a hot press provided with a suitable template, removal of part of said coating elements in excess, honing of the portion of the rim coated by the coating elements and protective varnishing of the coated rim.

Description: The present industrial invention refers to a steering wheel for motor vehicles and the relative procedure to realise it. In the field of accessories for motor vehicles there are known steering wheels having a driving rim made of a plastic material. There are also some known steering wheels of finer aesthetic quality in which the rim is made of solid wood. The latter, in addition to being much more costly, are also heavier and they guarantee a lesser reliability in case of collision as compared to the more economical steering wheels with plastic rim. JP 08 310 407 discloses a manufacturing method for molded article wherein a first wooden surface layer and a second wooden surface layer are arranged in a mold, a core wire is arranged within the space defined by the first wooden surface layer and the second wooden surface layer, and resin is introduced into that space.Another method of making a steering wheel, according to the preamble of claim 1 is known from DE-19528788. In view of the state of the art described, object of the following industrial invention is to realise a steering wheel that would combine, the characteristics of a low cost, lightness and reliability in case of collision that are typical of the steering wheels with a plastic rim, with the characteristics of a finer aesthetic quality of the steering wheels with a solid wood rim. According to the invention there is also provided a procedure for the realisation of a steering wheel for motor vehicles comprising a driving rim with a polyurethane core, characterised in that it comprises the following phases: grinding of the surface of said polyurethane core, realisation of a couple of coating elements of material with aesthetically finer quality having plane shape and size congruent to at least one portion of said polyurethane core, application of said coating elements to said polyurethane core and respective bending of the same by means of a hot press provided with a suitable template, removal of part of said coating elements in excess, honing of the portion of the rim coated by the coating elements, protective varnishing of the coated rim. Preferably, in case it is desirable to coat the steering wheel with briar wood, said couple of coating elements is realised by shearing briar wood sheets available on the market in the suitable shape and dimensions. If instead it is desirable to coat the steering wheel with a kind of wood with veining that would not consent the bending to be parallel to the veining itself, as for example mahogany wood, said couple of coating elements is realised by winding and gluing sheets of wood in spiral to form a drum, from which plane rings of wood, or ring portions are subsequently created, by shearing or shear turning, which can be applied to said polyurethane core. The characteristics of the present invention will be rendered even more evident by the following detailed description of some embodiments thereof, that are illustrated as non-limiting examples in the enclosed drawings, where: Figure 1 shows the diametric section of a core of a driving rim of a steering wheel according to the present invention, prior to its coating; Figures 2a-2c show the initial phases common to a first and a second procedure according to the present invention; Figure 3 shows a sheet of briar wood for the coating of the core of the driving rim according to a first procedure of production according to the invention; Figures 4a-4c show additional phases of said first procedure; Figure 5 shows a drum of wood for the production of coating elements according to a second procedure for the production according to the present invention; Figures 6a-6c show additional phases of said second procedure; With reference to Figure 1 it shows a section of a driving rim 1 according to a diametric plane passing through its axis 25; the rim 1 consists essentially of a core 3 of polyurethane and of a metallic reinforcement 2. Said driving rim 1 represents the basic elements from which to start to realise a steering wheel according to the invention, for example through the two procedures of production that will be now described. The first procedure refers to the realisation of a steering wheel coated with briar wood. The surface of said core 3 in polyurethane is ground at first and then coated with a fabric 4 either natural or synthetic or glass fibre base or carbon base or other, or with wood, using suitable glues resistant to heat and humidity. As shown in Figures 2a-2c, the coating of the core 3 with the fabric 4 is accomplished in several phases. A ring of fabric 4 with dimensions congruent to the polyurethane core 3 is applied on the upper part 10 of the driving rim 1 (Figure 2a). Subsequently the parts of fabric 4 in excess are removed and another ring of fabric 4 is applied on the lower part 11 of the rim 1 (Figure 2b). Then the part of the fabric 4 in excess is removed again (Figure 2c). A coating of reinforcement fabric 5 is applied to a surface of a sheet 15 of briar wood available on the market; the sheet 16 thus obtained is then sheared into plane rings 18 with size and shape congruent to the steering wheel to be realised (Figure 3). By means of a hot press provided with suitably shaped templates and by means of appropriate glues resistant to heat arid humidity, said rings 18 are bent and glued on the polyurethane core 3 following the phases shown in Figures 4a-4c. With reference to Figure 4a, a ring 18 of briar wood and fabric is applied on the upper part 20 of the driving rim 7 previously coated with fabric. Subsequently the parts in excess of the ring 18 of briar wood and fabric are removed and another ring 18 of briar wood and fabric is applied on the lower part 21 of the rim 7 (Figure 4b). Then once more the exceeding part of the ring of briar wood and fabric 18 applied to the lower part 21 of the rim 7 is removed, as shown in Figure 4c. Said rings 18 of briar wood and fabric can be formed by the assembly of more proportions of rings 19 shown in Figure 3, so as to get the most out of the sheet 16 of briar wood and fabric. Afterwards there is a phase of honing of the briar wood surface according to procedures substantially equal to those normally used for the honing of solid wood steering wheels. Therefore the procedure provides for the varnishing of the briar wood with a thickness of varnish such as to guarantee the maximum aesthetic and functional quality and the protection of the wood underneath. The second procedure of production illustrated in Figures 5, 6a-6c refers to the realisation of a coated steering wheel or other kind of wood with veining that do not allow its bending parallel to the veining itself. The surface of the driving rim 1 of Figure 1 is at first ground and then coated with a retaining fabric 4 by means of appropriate glues resistant to heat and to humidity, according to phases of procedure substantially equal to those illustrated in Figures 2a-2c. The realisation of a couple of coating elements of wood requires a greater working as compared to the first procedure. As shown in Figure 5, a sheet of mahogany wood or other wood of the aforementioned kind, is winded and glued in spiral so as to form a drum 30. From that drum rings of wood of plane shape are created, by means of shearing or shear turning. The realisation of said drum 30 is made necessary by the employment of a kind of wood that, as said previously, has veining that do not consent bending in direction parallel to it. In this way, instead, it is possible to give the wood rings the desired shape without problems of breakage of the same wood. On the surface of the rings 31 that must be glued to the rim 7 previously coated by the fabric 4, a coating in reinforcement fabric 5 is preferably applied. The rings 35 in mahogany wood and fabric thus formed are glued by means of a hot press provided with templates suitably shaped by means of appropriate glues resistant to heat and humidity by following steps essentially analogous to those shown in Figures 6a-6c. The honing phase of the mahogany wood surface then follows according to procedures substantially equal to those employed for the honing of solid wood steering wheels. The subsequent varnishing of the mahogany wood is in polyester with the same characteristics indicated before. With procedures analogous to the ones described it is possible to realise a steering wheel only partially covered with briar wood or wood, with the remaining part of another material, for example leather. In that case, in order to prevent unnecessary wastes of material, the ring of wood is sheared into portions of rings sufficiently large so as to coat only the zone of the steering wheel of interest.

Claims: Procedure for the realisation of a steering wheel comprising a driving rim (1) with a polyurethane core (3), the realisation of a couple of coating elements of material with aesthetically finer quality (18, 19, 31) having plane shape and size congruent to at least one portion of said polyurethane core (3), characterised in that it comprises the following phases: a) grinding of the surface of said polyurethane core (3), b) application of said coating elements (18, 19, 31) to said polyurethane core and respective bending of the same by means of a hot press provided with a suitable template, c) removal of part of said coating elements in excess, d) honing of the portion of the rim coated by the coating elements, e) protective varnishing of the coated rim. Procedure according to claim 1, characterised in that said couple of coating elements are in the shape of portions of rings (19). Procedure according to claim 1, characterised in that said couple of coating elements are in the shape of rings (18, 31). Procedure according to claim 2 or 3, characterised in that said coating elements (18, 19) are in briar wood. Procedure according to claim 4, characterised in that said coating elements (18, 19) in briar wood are obtained by shearing a sheet of briar wood. Procedure according to claim 2 or 3, characterised in that said coating elements (31) are of a wood with veining that does not allow bending parallel to the veining itself. Procedure according to claim 6, characterised in that said coating elements of wood (31) are realised by means of winding and gluing in spiral a sheet of wood until a drum (30) is formed and of subsequent shearing of said drum (30) perpendicular to its axis so as to form plane rings. Procedure according to claim 7, characterised in that said wood is mahogany wood. Procedure according to any of the claims from 1 to 8, characterised in that , after said phase a), said at least one portion of polyurethane core (3) is coated by a retaining fabric (4). Procedure according to any of the claims from 1 to 9, characterised in that on the surface of said coating elements (18, 19, 31) in contact with said polyurethane core (3) a reinforcement fabric (5) is applied. Procedure according to claim 10 in that it depends on claim 9, characterised in that said retaining and reinforcement fabrics (4, 5) get glued. Procedure according to claim 11, characterised in that for gluing said retaining and reinforcement fabrics (4, 5) glues resistant to heat and to humidity are used.

Inventors: CATTANEO MARCO, CATTANEO, MARCO
Applicants: BREED AUTOMOTIVE TECH, BREED AUTOMOTIVE TECHNOLOGY, INC.
Application year: 1998
Main classification: B62D1
IPC codes: B29C70, B62D1