Abstract:
The present invention relates to a steering wheel assembly comprising a support element ( 10 ) having at least one click-stop element ( 11 ), at least one guide bush ( 20 ) for connection to an airbag module, wherein the guide bush ( 20 ) is connected to the click-stop element ( 11 ) by a click-stop connection and the click-stop connection having play so that the guide bush ( 20 ) is movable relative to the click-stop element ( 11 ) in the vertical direction. By the target to describe such steering wheel assembly which has a simple structure it is provided that the support element ( 10 ) includes at least one first contact sheet ( 30 ) and the guide bush ( 20 ) includes at least one second contact sheet ( 40 ), wherein the first contact sheet ( 30 ) is arranged in its mounting position beneath the guide bush ( 20 ) so that the second contact sheet ( 40 ) is made to contact the first contact sheet ( 30 ) by movement of the guide bush ( 20 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to a steering wheel assembly according to the preamble of claim  1 . Such steering wheel assembly is known, for example, from DE 10 2012 002 722 A1. 
         [0002]    DE 10 2012 002 722 A1 describes a bearing unit having, on the one hand, a steering wheel-side part and, on the ether hand, a module-side part which serve for connecting an airbag module to a steering wheel. The steering wheel-side part is coupled directly to the support element of the steering wheel assembly and is thus connected to the steering wheel. The module-side part and the steering wheel-side part are biased against each other so that the airbag module is arranged to be spaced apart from the support element in an idle position of the module-side part. The airbag module is movable against the biasing force toward the support element, wherein the module-side part and the steering wheel-side part of the bearing unit abut against each other. A horn contact is provided to be structurally separated from the bearing unit. 
         [0003]    The known arrangement is complex in respect of the number of component parts that are required, apart from the mechanical retaining and guiding elements, so as to establish a horn contact between the airbag module and the support element. 
       SUMMARY OF THE INVENTION  
       [0004]    It is the object of the invention to describe a steering wheel assembly having a simple structure. Furthermore it is the object of the invention to describe a steering wheel comprising such steering wheel assembly and a method of actuating the horn. 
         [0005]    In accordance with the invention, this object is achieved with respect to the steering wheel assembly by the subject matter of claim  1 , with respect to the steering wheel by the subject matter of claim  15  and with respect to the method of actuating a horn by the subject matter of claim  16 . 
         [0006]    The steering wheel assembly according to the invention includes a support element having at least one click-stop element. Furthermore the steering wheel assembly comprises at least one guide bush for connection to an airbag module. The guide bush is connected to the click-stop element by a click-stop connection. The click-stop connection has play so that the guide bush is movable relative to the click-stop element along the longitudinal axis of the guide bush from an idle position into a hooting position. The support element includes at least one first contact sheet. The guide bush includes at least one second contact sheet. The first contact sheet is associated with the click-stop element and is arranged in its mounting position beneath the guide bush so that the second contact sheet can be made to contact the first contact sheet by the longitudinal movement of the guide bush. 
         [0007]    Hence, for actuating the horn the second contact sheet of the guide bush is temporarily connected to the first contact sheet arranged at the support element and in this way the horn contact is established. The click-stop element and the guide bush have a multiple function. On the one hand, in the finally assembled state they effectuate the mechanical guiding of the airbag module relative to the support element. On the other hand, the guide bush and the click-stop element together form the guiding for the horn contacts. For this, the second contact sheet is provided at the guide bush. Moreover, the first contact sheet is associated with the click-stop element and is arranged in its mounting position beneath the guide bush so that the second contact sheet can be made to contact the first contact sheet by the longitudinal movement of the guide bush. Thus additional components for fastening and guiding the second contact sheet are dispensed with so that a compact assembly requiring little space is provided. 
         [0008]    In accordance with the invention, the mechanical guide of the airbag module relative to the support element is combined with the mechanical guide of the horn contacts in one single component group, i.e. in the group comprising, especially consisting of the guide bush and the click-stop element. 
         [0009]    Advantageous further developments of the invention are described in the subclaims. 
         [0010]    For stable fastening of the airbag module and safe mechanical guiding the steering wheel assembly can include three click-stop connections of this type each of which comprises a click-stop element and a guide bush having respective contact sheets arranged thereon. 
         [0011]    In a preferred embodiment of the invention the second contact sheet is connected to an underside of the guide bush. By arranging the second contact sheet at the underside of the guide bush a simple and stable fixing of the second contact sheet is brought about. The second contact sheet is fixedly connected to the guide bush. The connection of the second contact sheet to the guide bush can be made, for example, by pins disposed at the guide bush. After arranging the second contact sheet said pins are melted on, for instance, and thus fix the sheet to the guide bush in a positive-locking manner. Another advantage of the underside arrangement of the second contact sheet consists in the fact that the distance between the idle position and the hooting position of the second contact sheet is reduced hereby. 
         [0012]    In another preferred variant of the present invention, the shape of the second contact sheet is adapted to the shape of a lateral profile of the guide bush. In this way substantially the full surface of the second contact sheet can rest on the guide bush, thereby a stable support being obtained. 
         [0013]    Furthermore, the guide bush can have at least one lateral retaining arm. In particular, the guide bush can have two lateral retaining arms. The two retaining arms can be arranged to be opposed, especially diametrically opposed. The lateral retaining arm serves for positioning the second contact sheet fastened thereto and making the latter to contact a desired area of the first contact sheet. 
         [0014]    Preferably the second contact sheet has at least one recess. A lower bush portion of the guide bush passes through said recess. The recess of the second contact sheet can surround the lower bush portion of the guide bush at least partially, especially completely. By this recess the positioning of the second contact sheet is facilitated. The lower bush portion serves as guide element interacting with the click-stop element as guiding counterpart. 
         [0015]    In another preferred embodiment of the steering wheel assembly according to the invention an upper bush portion of the guide bush is connected to the airbag module. Between the lower bush portion and the upper bush portion the second contact sheet is arranged. The connection between the airbag module and the guide bush can be configured in a way known per se. By arranging the second contact sheet between the upper and lower bush portions a sufficiently safe distance from the first contact sheet in the idle position is provided. 
         [0016]    In a preferred embodiment of the invention the first contact sheet includes at least one arm having a contact portion, especially two arms. Each of the two arms of the first contact sheet has a contact portion and permits making safe contact with the second contact sheet. The click-stop element can be arranged between the arms of the first contact sheet. This arrangement is an example of associating the first contact sheet with the click-stop element. The two arms can be arranged in V-shape. The two arms of the first contact sheet are arranged on the support element so that substantially the full surface thereof rests on the support element. 
         [0017]    Preferably the second contact sheet has at least two contact portions. The at least two contact portions of the second contact sheet correspond to the at least two contact portions of the first contact sheet and can be made to contact the same for hooting. In the idle position and in the hooting position the contact portions of the two contact sheets are arranged in parallel. Both contact portions of the first contact sheet contact both contact portions of the second contact sheet in the hooting position. 
         [0018]    It is sufficient for triggering the hooting signal when a contact portion of the second contact sheet contacts the corresponding contact portion of the first contact sheet. It is achieved in this way that even when the guide bush is inclined, i.e. in the case of an irregular movement of the second contact sheet, the horn is safely actuated. 
         [0019]    Furthermore, it may be provided that each of the two contact portions of the second contact sheet forms an extension extending downwards in the mounting position. When each of the two contact portions of the second contact sheet is arranged at said extension, the distance between the first and second contact sheets in the idle position and thus the distance to be covered by the second contact sheet to the hooting position is reduced. Thus the responsive behavior of the horn can be set. 
         [0020]    In a preferred embodiment of the invention, the two contact portions of the first contact sheet are electrically connected by a connecting element. In order not to couple each individual contact portion of the first contact sheet to the electric circuit for triggering the horn signal it is advantageous when the two contact portions of the first contact sheet are electrically interconnected by a connecting element. Thus for the first contact sheet a single electric connection is sufficient for connection to the circuit. 
         [0021]    In another preferred embodiment of the invention, each of the two contact portions of the first contact sheet and/or of the second contact sheet has at least one elevated contact point. The first contact sheet can be impressed in a foamed support element, for example, and can be positively fastened to the support element by fixing points. The fixing points can project from the surface of the first contact sheet. This is due to excessive material accumulating on the surface of the first contact sheet and forming a slight elevation vis-à-vis the contact surface of the first contact sheet at this point. In order to ensure the contact between the first and second contact sheets despite this material elevation the first and/or the second contact sheet has elevated contact points projecting above all other material elevations on the first contact sheet. 
         [0022]    In a preferred embodiment the first contact sheet at least partially surrounds the click-stop element. In other words, the first contact sheet is arranged at least partially along the periphery of the click-stop element. It is not absolutely necessary in this context that the contact sheet corresponds to the peripheral shape of the click-stop element. The first contact sheet partially surrounds the click-stop element, when e.g. the contact sheet includes arms arranged in V shape, as explained above, between which the click-stop element is arranged. 
         [0023]    Arranging the contact sheet around the click-stop element facilitates the positioning of the first contact sheet on the support element and saves constructed space in the steering wheel assembly. 
         [0024]    In a further preferred embodiment of the steering wheel assembly according to the invention the click-step element has at least one stop tongue, especially two stop tongues. The stop tongue extends in its mounting position upwards relative to the support element. The stop tongue engages with the guide bush. By the stop tongue the guide bush is connected and retained to the click-stop element. The connection between the stop tongue and the guide bush has play in the longitudinal direction of the guide bush such that the guide bush is movable relative to the click-stop element in the longitudinal direction of the guide bush. The play between the stop tongue and the guide bush corresponds to the distance between the idle position and the hooting position. The same applies to the click-stop element having two stop tongues. 
         [0025]    Consequently, the stop tongue has a double function. On the one hand, it constitutes a stop for the guide bush restricting the longitudinal movement of the guide bush from the hooting position into the idle position and fixing the airbag module in the idle position at the support element. On the other hand, the stop tongue allows for the guided movement of the airbag module from the idle position into the hooting position of the guide bush and vice versa. 
         [0026]    Preferably, a reset spring is arranged in the guide bush which acts on the click-stop element, on the one hand, and on the guide bush, on the other band. After triggering the horn signal and lifting the pressure the reset spring exerts a resetting force on the guide bush which returns the latter into its idle position together with the airbag module. In order to save additional components inside the steering wheel assembly the reset spring is arranged in the guide bush. 
         [0027]    The present invention also relates to a steering wheel comprising a steering wheel assembly as described above. 
         [0028]    It is provided in a preferred embodiment that the airbag module is connected to at least one, especially three guide bushes which are connected to at least one, especially three click-stop elements fixed at the support element. 
         [0029]    Within the scope of the invention, a method of actuating a horn is disclosed and claimed in which a force moving the guide bush from the idle position into the hooting position is applied to a steering wheel according to the invention, wherein the second contact sheet is made to contact the first contact sheet by the longitudinal movement of the guide bush. The method of actuating a horn excels by a facilitated actuation of the horn function, because the horn function is realized with a small number of components. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0030]    Hereinafter the invention is explained in detail by way of an embodiment with reference to the enclosed schematic drawings, in which: 
           [0031]      FIG. 1  shows a perspective view of a steering wheel assembly according to the invention in accordance with a preferred embodiment; 
           [0032]      FIG. 2  shows a perspective view of the steering wheel assembly according to  FIG. 1 , wherein a guide bush is connected to a click-stop element; 
           [0033]      FIG. 3  is a bottom view of the guide bush according to  FIG. 1 ; and 
           [0034]      FIG. 4  is a side view of the guide bush according to  FIG. 1 . 
       
    
    
     DESCRIPTION 
       [0035]    In  FIG. 1  a steering wheel assembly is shown which is mounted in a steering wheel for an automotive vehicle. Within the scope of the invention both the steering wheel assembly as sub-unit of the steering wheel and the steering wheel comprising the steering wheel assembly are disclosed and claimed. All features of the steering wheel assembly are also disclosed in connection with the steering wheel. 
         [0036]    The steering wheel assembly includes a support element  10 . The support element  10  is foamed. A click-stop element  11  is connected to the supped element  10 . The click-stop element  11  is impressed into the foam of the support element  10  during manufacture and is thus fixed to the support element  10 . 
         [0037]    In the illustrated embodiment the click-stop element  11  has a cylindrical shape. Other shapes are possible. Furthermore the steering wheel assembly includes a guide bush  20 . The guide bush  20  is connected to an airbag module after final assembly of the steering wheel in a way known per se end not described in detail here. As is shown in  FIG. 2 , the guide bush  20  is connected to the click-stop element  11  by a click-stop connection. The click-step connection has play which is set so that the guide bush  20  is movable relative to the click-stop element  11  in the longitudinal direction of the guide bush  20 . 
         [0038]    For this purpose, the guide bush  20  is supported to be longitudinally movable in the click-stop element  11 . 
         [0039]    The support element  10  includes a first contact sheet  30 . The guide bush  20  includes a second contact sheet  40 . The first contact sheet  30  is arranged in its mounting position beneath the guide bush  20  at the support element  10 . By movement of the guide bush  20  the second contact sheet  40  can be made to contact the first contact sheet  30 . 
         [0040]    Associating the first contact sheet  30  with the click-stop element  11  is resulting from the arrangement of the first contact sheet  30  beneath the guide bush  20  as well as from the guiding function of the guide bush  20  and of the click-stop element  11 . In other words, the first contact sheet  30  is arranged in the motion path of the second contact sheet  40  which is defined by the position of the click-stop element  11 . The first contact sheet  30  therefore is arranged closely to the click-stop element  11  and in so far is associated with the latter. 
         [0041]    The second contact sheet  40  shown in  FIGS. 1 to 4  is connected to the underside  21  of the guide bush  20 . The second contact sheet  40  is adapted to the shape of the lateral profile  22  of the guide bush  20  (cf.  FIGS. 3 and 4 ). In the bottom view (cf.  FIG. 3 ) of the guide bush  20  the second contact sheet  40  ends with the edge of the guide bush  20 . In the side view (cf.  FIG. 4 ) of the guide bush  20  the second contact sheet  40  is adapted to the contour, especially the stepped contour of the guide bush  20 . The full surface of the second contact sheet  40  is adjacent to the guide bush  20 . 
         [0042]    For electric coupling the second contact sheet  40  includes a terminal  44  projecting above the edge of the guide bush  20 . 
         [0043]    The first contact sheet  30  equally comprises a terminal  38 . By the terminals  38 ,  44  the two contact sheets  30 ,  40  are electrically connected to the electric horn circuit. When the first contact sheet  30  is connected to the second contact sheet  40  by a joint contact, the electric horn circuit is closed and a horn signal is triggered. 
         [0044]    The guide bush  20  includes two lateral retaining arms  23 ,  24 . The lateral retaining arms  23 ,  24  are arranged to be opposed on both sides of the guide bush  20 . The guide bush  20  is symmetrical in the bottom view (cf.  FIG. 3 ). 
         [0045]    The second contact sheet  40  is adjacent to the two retaining arms  23 ,  24 . In this way safe and stable fixing of the second contact sheet  40  to the guide bush  20  is obtained. The second contact sheet  40  is connected to the guide bush  20  by pins  27  arranged at the guide bush  20 . After attaching the second contact sheet  40  onto the guide bush  20  said pins  27  are melted on. The melted-on pins  27  are flattened on the side of the second contact sheet  40  facing away from the guide bush  20 . Thus the pins  27  positively fix the second contact sheet  40  on the guide bush  20 . The risk of damaging the second contact sheet  40  is reduced by this adaptation of the shape to the lateral profile  22  of the guide bush  20 . The lateral retaining arms  23 ,  24  serve for the second contact sheet  40  connected thereto being made to contact a desired area of the first contact sheet  30  in a specified and advantageous manner. 
         [0046]    The second contact sheet  40  includes two contact portions  42 ,  43  in the area of the two lateral retaining arms  23 ,  24 , as illustrated in  FIGS. 3 and 4 . Each of the two contact portions  42 ,  43  forms an extension extending downwards in the mounting position. This results in a stepped profile of the second contact sheet  40  in the area of the contact portions  42 ,  43 . The retaining arms  23 ,  24  are formed to be matching and are connected to the two extensions of the contact portions  42 ,  43 . Hereby the distance of the second contact sheet  40  from the first contact sheet  30  is reduced in the idle position. 
         [0047]    The guide bush  20  includes an upper bush portion  26  and a lower bush portion  25 . The upper bush portion  26  is connected to the airbag module. The connection between the airbag module and the guide bush  20  is configured so that different airbag modules can be fastened to the upper bush portion  26  of the guide bush  20 . Furthermore, the second contact sheet  40  includes a central recess  41  as shown in  FIGS. 3 and 4 . The lower bush portion  25  passes through said recess  41 . The second contact sheet  40  completely encompasses the lower bush portion  25  in the shown embodiment. The recess  41  facilitates positioning of the second contact sheet  40  on the guide bush  20 . 
         [0048]    Between the upper bush portion  26  and the lower bush portion  25  the second contact sheet  40  is arranged. The lower bush portion  26  is accommodated by the click-stop element  11  and serves as guide. 
         [0049]    In  FIGS. 1 and 2  a first contact sheet  30  is illustrated which is arranged at the support element  11  in the area of the click-stop element  11  and has two arms  31 ,  32 . The two arms  31 ,  32  are arranged in V shape to each other and partly enclose the click-stop element  11 . Each of the two arms  31 ,  32  has a contact portion  33 ,  34  which makes the connection to the corresponding contact portion  42 ,  43  of the second contact sheet  40 . 
         [0050]    The two contact portions  33 ,  34  are electrically connected by a connecting element  35 . The connecting element  35  is arranged between the two arms  31 ,  32 . The two arms  31 ,  32  extend in V shape away from the connecting element  35  and end on each side of the click-stop element  11 . 
         [0051]    The two contact portions  33 ,  34  are arranged at the end of each of the arms  31 ,  32 . The two contact portions  33 ,  34  are arranged to be opposed. The click-stop element  11  is disposed between the two contact portions  33 ,  34 . 
         [0052]    Moreover, each of the two contact portions  33 ,  34  of the first contact sheet  30  has an elevated contact point. The first contact sheet  30  is fixed in the foamed support element  10 . The first contact sheet  30  is fixed to the support element  10  by impressing the first contact sheet  30  into the foam of the support element  10 . The foam is pressed through small orifices  36  and is flattened on the upper side  37  of the first contact sheet  30 . The upper side  37  corresponds to the side of the first contact sheet  30  facing away from the support element  10 . After the foam is hardened, the first contact sheet  30  is positively connected to the support element  10 . The foam hardened on the upper side  37  of the first contact sheet  30  forms a slight elevation projecting from the upper side  37  of the first contact sheet  30 . In order to ensure that despite said material elevation a contact can be established between the second contact sheet  40  and the first contact sheet  30 , the two contact portions  33 ,  34  of the first contact sheet  30  include a sufficiently elevated contact point projecting above all other material elevations. 
         [0053]    The two contact portions  42 ,  43  of the second contact sheet  40  are made to contact the two contact portions  33 ,  34  of the first contact sheet  30  during the hooting operation. As soon as the first contact sheet  30  contacts the second contact sheet  40 , the electric circuit between the two contact sheets  30 ,  40  is closed and the horn signal is triggered. 
         [0054]      FIGS. 1 and 2  illustrate that the click-stop element  11  includes two stop tongues  12 ,  13 . The two stop tongues  12 ,  13  extend upwards related to the support element  10  in their mounting position. The step tongues  12 ,  13  are engaged with the guide bush  20 .  FIG. 3  illustrates that the guide bush  20  comprises two seats  28  matching the two stop tongues  12 ,  13 , the seats enabling the stop tongues  12 ,  13  to engage in the guide bush  20 . 
         [0055]    For the longitudinal movement the seats  28  are formed in the guide bush  20  as guides in which the stop tongues  12 ,  13  of the click-stop element  11  are arranged to be longitudinally movable. In this way the play between the guide bush  20  and the click-stop element  11  is obtained. Other connections having play are possible. 
         [0056]    The seats  28  form breakthroughs extending in parallel to the longitudinal axis of the guide bush  20  so that the guide bush  20  is positively guided in the longitudinal direction. The seats  28  are formed in the retaining arms  23 ,  24 . The shape of the breakthroughs and seats  28 , resp., substantially corresponds to the shape of the stop tongues  12 ,  13 . 
         [0057]    The click-stop connection between the guide bush  20  and the click-stop element  11  includes an upper step defining the idle position of the guide bush  20 . The stop is formed by an undercut of the stop tongue  12 ,  13  and a contacting edge of the guide bush  20  interacting with the undercut and restricting a longitudinal movement of the guide bush  20 . 
         [0058]    The play between the guide bush  20  and the click-stop element  11  is set so that in the hooting position a contact is established between the second contact sheet  40  and the first contact sheet  30 . 
         [0059]    The lower bush portion  25  is arranged between the stop tongues  12 ,  13 , concretely speaking between lands of the stop tongues  12 ,  13 , and is retained by the same. The click-stop element includes a recess which is formed coaxially with the lower bush portion  25 . The recess can accommodate the lower bush portion  25 . 
         [0060]    The lower bush portion  25  has a cylindrical shape. Other shapes are Possible. The shape of the recess of the click-stop element is adapted to the shape of the lower bush portion  25 . 
         [0061]    In the inner area the guide bush  20  has a cylindrical recess  29  serving as seat holder and guide for the reset spring  50 . The one end of the reset spring  50  acts on the guide bush  20 . The reset spring  50  is laterally held and supported by the cylindrical recess  29  of the guide bush  20 . The end of the reset spring  50  rests on the bottom of the cylindrical recess  29 . The other end of the reset spring  50  acts on the click-stop element  11 . This end of the reset spring  50  rests on the bottom of the cylindrical click-stop element  11 . After the second contact sheet  40  and the first contact sheet  30  have been made to contact and hereby the horn signal has been triggered, the guide bush  20  is returned into its idle position by the resetting force of the reset spring  50 . In order to save additional components within the steering wheel assembly, the guide bush  50  serves as holder for the reset spring  50 . 
         [0062]      FIGS. 1 and 2  illustrate a cutout of a steering wheal, especially a support element  10 . In the shown embodiment the steering wheel is equipped with three click-stop elements  11  and three guide bushes  20 . The three click-stop elements  11  are fastened on the support element  10  in triangular arrangement, in this manner, a precise orientation of the airbag module at the steering wheel is obtained. Each of the click-step elements  11  is embedded in the foam of the support element  10  or anchored in the foam of the support element  10 , respectively. The support element  10  has a recess in the area of the module seat for the airbag module. 
         [0063]    For actuating the horn the airbag module is forced downwards by the action of force. The guide bush  20  to which the airbag module is fastened is moved downwards relative to the click-stop element  11 . As soon as the second contact sheet  40  contacts the first contact sheet  30  and in this way the electric connection is made between the first contact sheet  30  and the second contact sheet  40 , the electric circuit is closed and the horn signal is triggered. 
         [0064]    When the action of force on the airbag module is lifted, the reset spring  50  returns the guide bush  20  and thus the airbag module into its idle position again, whereby the contact between the first contact sheet  30  and the second contact sheet  40  is interrupted and the horn signal falls silent. 
       LIST OF REFERENCE NUMERALS 
       [0000]    
       
           10  Support dement 
           11  click-stop element 
           12  stop tongues 
           13  stop tongues 
           20  guide bush 
           21  underside 
           22  lateral profile 
           23  lateral retaining arm 
           24  lateral retaining arm 
           25  lower bush portion 
           26  upper bush portion 
           27  pins 
           28  seats 
           29  cylindrical recess 
           30  first contact sheet 
           31  arm 
           32  arm 
           33  contact portion 
           34  contact portion 
           35  connecting element 
           36  orifices 
           37  upper side 
           38  terminal 
           40  second contact sheet 
           41  recess 
           42  contact portion 
           43  contact portion 
           44  terminal 
           50  reset spring