Abstract:
A vehicle steering wheel includes a gas bag module ( 16 ) and an immovably fastened component ( 18 ), in particular a shield, adjacent to the gas bag module ( 16 ). The vehicle steering wheel further includes at least one separate elastic positioning element ( 22 ) which establishes the position of the gas bag module ( 16 ) relative to the adjacent component.

Description:
TECHNICAL FIELD  
       [0001]     The invention relates to a vehicle steering wheel comprising a gas bag module.  
       BACKGROUND OF THE INVENTION  
       [0002]     Fastening a gas bag module to a vehicle steering wheel entails difficulties owing to the high requirements with respect to the positioning of the gas bag module. An inaccurate positioning of the gas bag module results not only in different gap measurements but can also lead to undesired noises through bearing friction or knocking of the gas bag module. Furthermore, the addition of the manufacturing tolerances of the components involved (cumulative tolerance) leads to projections and gaps which are difficult to control. This applies in particular to so-called floating horn gas bag modules, which are movable with respect to adjacent components of the vehicle steering wheel. Solutions known hitherto for positioning such gas bag modules are generally costly and cumbersome.  
         [0003]     It is an object of the invention to provide a vehicle steering wheel , in which the gas bag module is easy to install and is automatically positioned correctly.  
       BRIEF SUMMARY OF THE INVENTION  
       [0004]     In accordance with the invention, a vehicle steering wheel comprises a gas bag module and an immovably fixed component, in particular a shield, adjacent to the gas bag module. The vehicle steering wheel further comprises at least one separate elastic positioning element which establishes the position of the gas bag module relative to the adjacent component. The elastic positioning element presses the gas bag module into the desired position without further action, so that even in the case of a floating horn gas bag module a correct position is always reached after each actuation of the horn. The positioning elements, which can be small in size, therefore form a noise-free guide for the gas bag module. This makes small, controllable gaps and projections possible. The positioning elements are exchangeable and can be designed for various requirements.  
         [0005]     The positioning element may be used advantageously for the production of a horn contact for activating the horn. To this end, the positioning element may act on a horn contact element.  
         [0006]     According to a preferred embodiment of the invention, the positioning element is a spring element having a support section and a detent section, the support section having a U-shaped profile with two arms, and the detent section being connected with one of the arms. In accordance with a favourable arrangement, in this construction of the positioning element the detent section can engage on the gas bag module, and the support section can be arranged between the adjacent component and a support.  
         [0007]     The positioning element is preferably designed so that it exerts a pre-stressing force onto the gas bag module in the axial direction of the vehicle steering wheel and/or in a perpendicular direction to the axial direction of the vehicle steering wheel, so that in addition to the spatial positioning, the positioning element according to the invention also provides for an actuating force and a restoring force when the horn is actuated, and vibrations of the gas bag module are avoided.  
         [0008]     The positioning of the gas bag module by the positioning element according to the invention preferably represents a supplement to a primary fastening mechanism which is independent of the positioning element.  
         [0009]     A correct positioning of the gas bag module in all directions perpendicular to the steering wheel axis can be achieved most simply by at least three positioning elements distributed over the periphery of the gas bag module.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  shows a top view of a vehicle steering wheel according to the invention;  
         [0011]      FIG. 2  shows a perspective view of a positioning element; and  
         [0012]      FIG. 3  shows a section through a portion of the vehicle steering wheel of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]     In  FIG. 1 a  vehicle steering wheel  10  is shown with a steering wheel rim  12 , spokes  14  and a centrally arranged gas bag module  16 . The gas bag module  16  is constructed as a so-called floating-horn gas bag module, i.e. the entire gas bag module can be pressed down in the axial direction of the vehicle steering wheel  10  in order to actuate the horn. The gas bag module  16  is surrounded by a shield  18  which is fastened immovably on the vehicle steering wheel  10 .  
         [0014]     Special elastic positioning elements  22  are provided at three sites  20  for positioning and guiding the gas bag module  16  in relation to the immovable components of the vehicle steering wheel  10 , in particular to the adjacent shield  18 . The positioning elements  22  are arranged substantially at the same angular distance from each other on the outer periphery of the gas bag module  16 .  
         [0015]      FIG. 2  shows a single positioning element  22 . The positioning element  22  is a spring element and has a support section  24  with a U-shaped profile. A detent section  28  with an angled tongue  30  adjoins the upper arm  26  of the U-shaped section. The positioning element  22  has, in addition, first fitting sections  32  and opposed second fitting sections  34  and also an upwardly bent nose  36 .  
         [0016]     In  FIG. 3  the vehicle steering wheel  10  is illustrated in the installed state, in which the shield  18  and the covering cap  38  of the gas bag module  16  lie opposite each other. The gas bag module  16  is fastened to the vehicle steering wheel  10  by means of a primary fastening mechanism (not shown) which is independent of the positioning elements  22 . In particular, the primary fastening mechanism is a detent mechanism. In the case of an activation of the gas bag module  16  the shooting forces are transferred to the vehicle steering wheel  10  via this primary connection. The positioning elements  22 , on the other hand, serve for the spatial positioning and guiding of the gas bag module  16 .  
         [0017]     As shown in  FIG. 3 , the positioning elements  22  are arranged so that the support section  24  is held in a cut-out of the shield  18  and rests on a support  40 . The nose  36  engages into a matching cut-out of the shield  18 , whilst the first fitting sections  32  rest against a side wall  42  of the covering cap  38  and the second fitting sections  34  rest against the shield  18 . In this way, a force-fitting fixing of the gas bag module  16  is provided in a plane perpendicular to the steering wheel axis.  
         [0018]     The detent section  28  of the positioning element  22  with the angled tongue  30  and the contour  44  of the side wall  42  of the covering cap  38  are coordinated with each other so that the covering cap  38  engages with the positioning element  22  by pushing in axially (secondary detent engagement). The form- or force-fitting axial fixing by the secondary engagement is designed so that a repeated installation and dismantling of the covering cap  38  is possible. The free tongue  30  of the detent section  28  is pre-stressed in the installed state, i.e. it exerts a force onto the covering cap  38  and hence onto the gas bag module  16 , which has a component in the axial direction and a component in a direction perpendicular thereto.  
         [0019]     When several positioning elements  22  are used, this results as a whole in a defined positioning of the gas bag module  16  relative to the adjacent shield  18  with a pre-stressing which counteracts vibrations of the movable gas bag module. Compression springs or suchlike which are otherwise usual for damping vibrations can therefore be dispensed with.  
         [0020]     If the gas bag module  16  is pressed down in axial direction to actuate the horn, the positioning element  22 , with the exception of the lower arm  46 , also moves practically without friction. The fitting sections  32 ,  34  and the detent section  28  provide for a guidance and an actuating force or restoring force, in order to offer a certain resistance to the movement of the gas bag module  16  and in order to move the gas bag module  16  back again into the initial position.  
         [0021]     The actuating of the horn can take place with the aid of a horn contact element  48  which is arranged on the lower arm  46  of the positioning element  22 , on the support  40  or on another component beneath the shield  18 , as illustrated in dashed lines in  FIG. 3 . By the gas bag module  16  being pressed down, the upper arm  26  of the positioning element  22  is moved onto the horn contact element  48  and thereby produces an electrical contact for activating the horn.  
         [0022]     The positioning elements  22  therefore fulfil several functions: The force-fitting spatial fixing of the gas bag module  16 , the pre-stressing of the gas bag module  16  to avoid vibrations, the guiding of the gas bag module  16  when the horn is actuated and also the establishing of the actuating force and the provision of the restoring force when the horn is actuated.