Steering wheel and method for manufacturing a steering wheel

Abstract

A steering wheel (10) is presented, comprising a frame (12) which includes a hub (14) designed for mounting the steering wheel (10) on a steering wheel mount of a motor vehicle, at least one grip section (16), preferably a steering wheel rim, and at least one spoke (18) connecting the hub (14) and the grip section (16), and at least one composite component (22, 24) which is mounted on the steering wheel side such that it forms a rear or side outer cover when the steering wheel (10) is mounted on the steering wheel mount. Furthermore, a method for manufacturing such a steering wheel (10) is presented.

Description

[0001] The present invention relates to a steering wheel for a motor vehicle, comprising a skeleton having a hub configured for mounting the steering wheel to a steering wheel mount of the motor vehicle, at least one grip portion, preferably a steering wheel rim, and at least one spoke connecting the hub and the grip portion. Furthermore, the invention relates to a method for manufacturing such a steering wheel.

[0002] Conventional steering wheels, such as those shown in DE 20 2004 012 304 U1, typically have a skeleton overmolded or foam-coated with a foam or plastic. This determines the final outer shape of the steering wheel, which is then optionally covered with thin coatings, such as leather. However, overmolded or foam-coated the skeleton involves additional, costly and technically complex manufacturing steps.

[0003] Therefore, non-foam- or non-injected steering wheels are increasingly being used. A fundamental problem with such steering wheels is that the closed cross-sectional profile of the steering wheel rim, which would otherwise be created by foam encapsulation, cannot be replicated solely by the metallic steering wheel skeleton without considerable effort. Furthermore, an enlargement of the rim area of ​​the steering wheel skeleton inevitably leads to a disadvantageous increase in weight. Rear covers or panels made of injection-molded plastic are therefore increasingly being used. For example, EP 1 602 549 A1 discloses a steering wheel for a motor vehicle in which the skeleton is covered with a rear cover part made of plastic. The cover part at least partially covers a lower area of ​​the steering wheel facing away from the driver and also forms a lower part of the steering wheel rim facing away from the driver.

[0004] The disadvantage, however, is that the steering wheels with simple plastic covers, which are common in the state of the art, do not meet a driver's subjective quality standards, or only inadequately so. Simple plastic covers provide an inadequate acoustic feel and produce a muffled sound. At the same time, the surfaces are heavily dependent on the tool-specific grain and compatible paint finishes, which in turn severely limits the design options.

[0005] Therefore, the object of the present invention is to provide a lightweight, cost-effective steering wheel for a motor vehicle that meets haptic and acoustic requirements while simultaneously allowing a high degree of customization. Furthermore, a cost-effective manufacturing process is to be specified.

[0006] The above-mentioned first object is achieved according to the invention by a steering wheel according to claim 1.

[0007] A steering wheel of the type mentioned above features at least one composite component (sandwich component) mounted on the steering wheel side in such a way that it serves as at least one rear or side outer cover when the steering wheel is mounted on the steering wheel mount. The composite component increases the damping of the cover and thus prevents a muffled steering wheel sound that the driver perceives as inferior.

[0008] Advantageous and expedient embodiments of the steering wheel according to the invention are specified in the subclaims.

[0009] Preferably, the composite component can cover a rear portion of the at least one spoke and / or the hub facing away from the rider.

[0010] Furthermore, it may be advantageous if the composite component covers a radially outer circumferential section of the at least one handle section.

[0011] In a preferred embodiment, the composite component can comprise a preformed, in particular deep-drawn, plastic film, onto which a filling material is applied, in particular foamed, on the inside. In other words, the composite component can preferably comprise a film that can be adapted to the shape of the skeleton or a foam coating of the skeleton by deep-drawing and that has the filling material on its inner side facing the skeleton or the foam coating.

[0012] Particularly preferably, the filling material can be a foam, preferably an expanding polypropylene (EPP) or a biodegradable material, for example based on corn starch.

[0013] In addition, it may be advantageous if the composite component, in particular the filling material, has at least one cavity which is designed to accommodate electrical components, such as cables or lines, and / or to align the composite component to the steering wheel.

[0014] According to a particularly advantageous development, the preformed film can have at least a first, translucent or transparent section and a second opaque section.

[0015] Preferably, the first section and the second section can be formed integrally from the preformed film, so that the transition between the first section and the second section is seamless. In other words, the film of the composite component can have sections with different levels of light transmission. The arrangement and design of these sections can be controlled, particularly during preforming or deep-drawing, without disruptive transitions, such as folds or steps, forming between the sections.

[0016] Furthermore, the steering wheel according to the invention can advantageously have at least one lighting device which is attached to the steering wheel in the region of the first section of the composite component.

[0017] To achieve the second object, the present invention further relates to a method for producing a steering wheel according to the invention according to claim 10. A steering wheel base body is initially provided. This steering wheel base body comprises the skeleton and, optionally, a partial foam coating around the skeleton. The skeleton can be produced for this purpose by a primary forming process, such as casting or injection molding. In the method according to the invention, the composite component is produced in a second process step before being attached to the steering wheel.

[0018] Advantageously, the composite component can be produced by preforming, in particular deep drawing, a film and backfoaming the preformed film with the filling material.

[0019] Furthermore, it may be advantageous if the composite component is fastened to the steering wheel side by ultrasonic welding, hot caulking, screwing, gluing and / or a snap-in connection, preferably to the skeleton or the foam encasing of the skeleton.

[0020] In other words, the invention relates to the steering wheel with the composite component used as the rear cover. The composite component is manufactured by preforming the thermoformable film and backfilling it with a lightweight filler material, such as EPP, to form a single unit. The film can be produced in a wide variety of colors, decors, and designs. Opaque and partially or completely translucent areas can be arranged seamlessly as desired. The filler material of the sandwich component can consist of lightweight industrial materials, such as EPP, or renewable materials, such as popcorn. The sandwich structure enables optimal sound absorption, which gives the composite component a high-quality sound. The filler material can also be used for easy positioning on the steering wheel or for attaching cables or other elements.

[0021] Further features and advantages of the invention will become apparent from the following description of a preferred embodiment and from the accompanying drawings, to which reference is made. In the drawings: - Fig. 1 a plan view of a steering wheel according to the invention according to an embodiment; and - Fig. 2 a sectional view of the steering wheel according to the invention Fig. 1.

[0022] In Fig. 1 shows a variant of a steering wheel 10 for a motor vehicle in a plan view, i.e., a front view facing the driver. The steering wheel 10 has a skeleton 12. The skeleton 12 is preferably manufactured in one piece by die casting or injection molding and, in turn, has a hub 14, a grip portion 16, and at least one spoke 18 connecting the hub 14 and the grip portion 16. The hub 14 is designed to ensure mounting of the steering wheel 10 on a steering wheel mount of the motor vehicle.

[0023] In the example shown, the grip section 16 is designed as a circumferential steering wheel rim, which in turn is connected to the hub 14 via four spokes 18. Alternatively, the grip section 16 can also comprise only one sector of the circumferential steering wheel rim. Furthermore, it is also conceivable for the circumferential steering wheel rim to be divided into several steering wheel rim sections, which in turn form a plurality of grip sections 16. Each of the plurality of grip sections 16 can then be connected to the hub 14 via at least one spoke 18, according to the invention.

[0024] As particularly in Fig. 2, the skeleton 12 in the preferred embodiment has a foam coating (overmolding) 20 on the handle section 16 in order to provide a driver with a larger grip surface when steering the motor vehicle and to enable a better feel.

[0025] On a rear side facing away from the driver (below in Fig. 2), the steering wheel 10 has a composite component 22 designed as a sandwich component. This composite component 22 is attached to the steering wheel side in such a way as to form an outer cover for the rear side of the skeleton 12. As in Fig. 2, the composite component 22 covers the spokes 18 and the hub 14 at least partially at the rear.

[0026] In addition, the steering wheel 10 according to the preferred embodiment has a further composite component 24 designed as an outer cover, which covers a radially outer section of the foam 20 of the skeleton 12 on the handle section 16.

[0027] The two composite components 22, 24 are essentially identical in construction. Each of the composite components 22, 24 has, on a side facing away from the skeleton 12 or the foam 20, a plastic film 26 that is preformed by deep drawing and, on the inside, i.e., on the side facing the skeleton 12 or the foam 20, is back-foamed with a foam 28, for example, an expanding polypropylene (EPP) or a biodegradable material based on corn starch. Thus, the composite components 22, 24 can be used to provide an outer cover for the steering wheel 10, which offers good noise dampening and thus ensures high-quality sound.

[0028] As mentioned above, the plastic film 26 of the composite components 22, 24 is preformed by deep drawing. Depending on the degree of deep drawing, the transparency or translucency of the plastic film 26 can be adjusted, which in turn significantly increases the design freedom for the steering wheel 10.

[0029] In the preferred embodiment, the plastic film 26 has at least a first translucent section 30 and a second opaque section 32. Because the first section 30 and the second section 32 are formed integrally by the plastic film 26, transitions between the first section 30 and the second section 32 can be carried out seamlessly, ie without disturbing folds or steps.

[0030] Furthermore, a lighting device 34 is arranged in the area of ​​the first section 30, so that light from the lighting device 34 passes almost exclusively through the first section 30. The lighting device 34 enables a lighting concept tailored to the vehicle and thus contributes to promoting design possibilities, particularly when illuminating the interior of the vehicle. The lighting device 34 is housed, for example, in a cavity 35 in the foam 28, which extends to the plastic film 26.

[0031] In order to be able to arrange electrical components, such as electrical lines or cables for the lighting device 34, in the steering wheel 10, at least one further cavity is formed in the composite component 22, 24, in particular in the foam 28 of the composite component 22, 24, according to the preferred exemplary embodiment.

[0032] In other words, at least one cable channel formed as a hollow space can be arranged in the foam 28 of the composite component 22, 24. This channel enables space-saving integration of the cables and / or other electrical components, optimized for the design of the steering wheel 10.

[0033] Furthermore, the at least one cavity can also be designed as an assembly aid, so that the composite component 22, 24 can be aligned through the cavity on the steering wheel 10, in particular the skeleton 12 or the foam encasing 20 of the skeleton 12. For this purpose, it may be expedient if the at least one cavity is designed in the form of a recess into which a projection formed on the steering wheel 10 engages.

[0034] In order to be able to fasten the composite components 22, 24 aligned with the steering wheel 10 to the latter, in particular to the skeleton 12 and / or the foam encapsulation 20 of the skeleton 12, a locking connection is formed between the steering wheel 10 and the respective composite component 22, 24 in the preferred embodiment. In particular, the composite component 22, 24 can have at least one locking lug for this purpose, which engages behind a corresponding locking projection of the steering wheel 10 in order to thus hold the composite component 22, 24 to the steering wheel 10. Alternatively, the at least one composite component 22, 24 can also be fastened to the steering wheel side by ultrasonic welding, hot caulking, screwing, or gluing. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 20 2004 012 304 U1

[0002] EP 1 602 549 A1

[0003]

Claims

[1] Steering wheel (10) with a skeleton (12) which has a hub (14) designed for mounting the steering wheel (10) on a steering wheel mount of a motor vehicle, at least one grip section (16), preferably a steering wheel rim, and at least one spoke (18) connecting the hub (14) and the grip section (16), characterized by at least one composite component (22, 24) which is mounted on the steering wheel side in such a way that it is a rear or side outer cover when the steering wheel (10) is mounted on the steering wheel holder. [2] Steering wheel (10) according to claim 1, characterized by that the composite component (22) covers a rear section of the at least one spoke (18) and / or the hub (14) facing away from the rider. [3] Steering wheel (10) according to claim 1 or 2, characterized by that the composite component (24) covers a radially outer circumferential section of the at least one handle section (16). [4] Steering wheel (10) according to one of claims 1 to 3, characterized by that the composite component (22, 24) has a preformed, in particular deep-drawn, plastic film (26) onto which a filling material (28) is applied, in particular foamed, on the inside. [5] Steering wheel (10) according to claim 4, characterized by that the composite component (22, 24), in particular the filling material (28), has at least one cavity which is designed to accommodate electrical components and / or to align the composite component (22, 24) on the steering wheel (10). [6] Steering wheel (10) according to claim 4 or 5, characterized by that the filling material is a foam (28), preferably expanding polypropylene or a biodegradable material, preferably based on corn starch. [7] Steering wheel (10) according to one of the preceding claims 4 to 6, characterized bythat the preformed plastic film (26) has at least a first, translucent or transparent portion (30) and a second opaque portion (32). [8] Steering wheel (10) according to claim 7, characterized by that the first section (30) and the second section (32) are formed in one piece by the preformed plastic film (26), so that a transition between the first section (30) and the second section (32) is seamless. [9] Steering wheel (10) according to claim 7 or 8, further characterized by at least one lighting device (34) which is attached to the steering wheel (10) in the region of the first section (30) of the composite component (22, 24). [10] Method for manufacturing a steering wheel (10) according to one of the preceding claims, comprising the following steps: a) Providing the skeleton (12), b) producing the composite component (22, 24), and c) fastening the composite component (22, 24) on the steering wheel side. [11] Method according to claim 10, characterized by that the composite component (22, 24) is produced by preforming, in particular deep drawing, a plastic film (26) and back-foaming the preformed plastic film (26) with a filling material (28). [12] Method according to claim 10 or 11, characterized by that the composite component (22, 24) is fastened to the steering wheel side by ultrasonic welding, hot caulking, screwing, gluing and / or a snap-in connection, preferably to the skeleton (12) or a foam covering (20) of the skeleton (12).

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