Patent Application
20050217413
The present invention relates to a steering wheel for a vehicle.
U.S. Pat. No. 3,714,844 discloses a steering wheel with a steering wheel skeleton comprising a flat metallic base material. The steering wheel skeleton comprises a steering wheel rim, spokes and a hub region that is connected to the radially inner ends of the spokes and on which a hub comprising a hub body is secured. The flat metal base material is formed as a casting. The hub is connected to the steering wheel skeleton on both its bottom side and its top side, whereby relatively narrow support surfaces are formed on shoulders on the hub.
EP 0 814 010 B1 discloses a steering wheel skeleton comprising a hub, spokes and rim in one piece and formed into its final shape by a process of reshaping of a sheet steel sheet section without cutting. For the formation of the hub, the steel sheet section comprises in the hub region a material doubling to provide the required stiffness and sufficient material for a serration.
There is provided in accordance with the present invention a steering wheel skeleton comprising a rim, spokes and a hub region that is connected to the radially inner ends of the spokes and on which a hub comprising a hub body is to be secured, wherein the steering wheel skeleton comprises a high-strength polyphase fine sheet steel.
A steering wheel according to the present invention has utility with a motor vehicle, but may also be employed with other vehicles such as watercraft or any other machine requiring a steering wheel. The represented embodiments have a steering wheel skeleton 1. The steering wheel skeleton comprises a rim 2, spokes 3 and a hub region in the form of a support plate 7 connected to the radially inner ends of the spokes. A hub 4 comprising a hub body is to be secured to the support plate 7. For the purpose of securing the hub 4 to the steering wheel skeleton 1, the hub 4 has a hub projection 8 projecting from its top side. The hub projection 8 is inserted through an opening 6 in the support plate 7. This ensures that the hub 4 can be arranged so that the axis of rotation 5 of the steering wheel is coaxial with a steering wheel shaft on which the steering wheel is mounted. A non-rotatable connection is created between the opening 6 and the hub 4 using the hub projection 8 and the inner circumference of the opening 6. The non-rotatable connection can be created by a serration or, preferably, as is shown in
The hub region for securing the hub is preferably formed by a plane support plate extending essentially perpendicular to the steering wheel shaft and comprising an opening around the steering wheel shaft. The hub is formed by a solid hub body with a through bore which on its top side comprises a medium-sized hub projection. The hub projection is inserted through the opening of the support plate and comprises on its circumference a shaping which with the inner circumference of the opening forms a non-rotatable connection. A serration created by one or several teeth and corresponding recesses can be provided between the circumference of the hub projection and the inner circumference of the opening. Circumferentially extending teeth engaging one another are preferably created on the inner circumference of the opening and on the outer circumference of the hub projection.
The skeleton base body for the steering wheel skeleton 1 is a steel sheet section made from a high-strength polyphase fine sheet steel. The steel sheet section can for instance be fabricated by stamping out of fine sheet steel. The final shape of the steering wheel skeleton 1 is achieved by a process of sheet reshaping without cutting, in particular by deep-drawing. In this manner the support plate 7 is given its shape which is sloped relative to the rim 2, whereby the spokes 3 can display a slanted or graduated shape, as can shown in the figures. The spokes 3 and the rim 2 can have an open cross-section form, for instance an essentially U-shaped or V-shaped or similar form. The rim 2 preferably has a closed form, whereby the closed form, as shown in
As already described above, during the deep-drawing or during the final shaping of the steering wheel skeleton, in particular in the hub region, the hub 4 can be secured to the support plate 7.
The high-strength polyphase fine sheet steel, out of which the steering wheel skeleton 1 is made, can for instance comprise a dual phase steel (cold rolled or hot rolled), the structure of which consists essentially of ferrite with a martensite content of up to approximately 20%. A dual phase steel (TRIP steel) with a ferrite/bainite matrix base and retained austenite elements, which during the reshaping process convert to hard martensite, is also suitable. This type of fine sheet steel is used during the bodywork manufacturing of motor vehicles. The base body of the steering wheel skeleton comprises a steel sheet section that is preferably formed by stamping from the polyphase fine sheet steel. The polyphase fine sheet steel is preferably a dual phase fine sheet steel. This sheet can display a thickness of 0.70 mm to 1.50 mm, for example 1.25 mm. The yielding point of the fine sheet steel lies between 320 N/mm2 and 400 N/mm2, preferably 380 N/mm2. The tensile strength of the fine sheet steel measures 570 N/mm2 to 700 N/mm2, preferably 600 N/mm2.
The reshaping during the forming of the steering wheel skeleton is preferably carried out by deep drawing. The draw point ratio of the high-strength fine sheet steel for this purpose lies preferably between 1.75 and 2.00 with a sheet thickness of 1 mm and with deep-drawing using a hemispherical plunger, which displays a diameter of 160 mm. The sheet steel preferably has a draw point ratio of approximately 1.9.
The support surface is arranged in a depression on the steering wheel skeleton. This depression can be created by a slanted arrangement and/or a graduated shape of the spokes. In this manner an assembly space for an airbag module is created in the skeleton interior on the top side of the support surface. The airbag module can be securely connected to the steering wheel skeleton preferably by spring-loaded latches and/or plug-in connections in the region of the support plate or in the region of the spokes.
In the figures the support plate 7 is positioned in a depression in the hub region facing the rim 2. This facilitates the installation of an airbag module 15. The securing of the airbag module 15 is preferably carried out by spring-loaded latches 14 that can be provided on the spokes 3 or in the region of the support plate 7. In the embodiments of FIGS. 1 to 5, the spring-loaded latches 14 are provided in the region of the support plate 7. The spring-loaded latches are positioned outside the top side of the hub 4, which is pressed against the bottom side of the support plate 7. In the embodiments of FIGS. 1 to 5, the spring-loaded latches are positioned between the radially inner ends of the spokes and the hub body. In each case the spring-loaded latch 14 can comprise a leg spring 17, 18, whereby the leg spring is preferably designed to be hairpin-shaped or U-shaped with two spring legs 17, 18 (FIGS. 3 to 5). On the airbag module 15 an engagement part 16 is allocated to each spring-loaded latch 14. The engagement parts 16 are hook-shaped and in a plugged-in state they lock with one of the two spring legs of the corresponding spring-loaded latch 14. In the represented embodiment one spring leg 17 is immovably secured to the steering wheel skeleton 1. The other spring leg 18 is resiliently movable. The resiliently movable spring leg 18 extends across an opening 20, which is provided in the sheet material of the steering wheel skeleton in the outer region of the support plate 7 for each spring-loaded latch 14. In the represented embodiment, three spring-loaded latches 14 and three allocated engagement parts 16 are provided on the airbag module 15. The airbag module 15 is, as shown in
A bias can be exerted on the airbag module 15 by a spring 22 opposing the plug-in direction 19, so that the angle of the hook is pressed against the spring leg 18, whereby additional securing is achieved. For this purpose, the spring 22 is positioned in the proximity of the spring-loaded latch 14 and supports its locking effect.
In the embodiment shown in
The two embodiments of the latches show that they can be released from their locking positions. Upon pressing the two spring legs 27 together, the lock shown in
In
The sheet parts 11 projecting downward between the spokes 3 are pushed to the side surfaces of the hub 4 by pressure, in particular high pressure to achieve a more or less cold-welded connection. This results in an anchoring of the hub 4 to the steering wheel skeleton 1 without bending the sheet parts 11 around the bottom side of the hub 4. Sheet parts 12, as shown in the embodiment of
To secure the airbag module 15 (not represented in detail) to the steering wheel openings 24 for spring-loaded latches or retention devices for securing the airbag module as described above are provided on upwardly bent straps 30, which are made in one piece with the steering wheel skeleton. The straps 30, together with the surfaces in which the openings 24 are arranged for the spring-loaded latches, extend beyond the top side of the support plate 7 as shown in
Many changes and modifications in the above described embodiments of the invention can, of course, be carried out without departing from the scope thereof. Accordingly, that scope is intended to be limited only by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2004 015 529.1 | Mar 2004 | DE | national |
