Abstract:
A vehicle steering wheel comprises a steering wheel body and at least one electric switch attached to the steering wheel body. The switch, for adaptation to the length of the fingers of a driver, is adjustably attached to the steering wheel body in such a way that it can be adjusted by the driver to assume various positions relative to the steering wheel body.

Description:
TECHNICAL FIELD 
     The invention relates to a vehicle steering wheel comprising a steering wheel body and at least one electric switch attached to the steering wheel body. 
     BACKGROUND OF THE INVENTION 
     The growing use of electronics in vehicles involves a constantly increasing number of functions which the driver of the vehicle can influence while driving. Aside from adjusting a ventilation or air-conditioning system, these include, for example, the operation of a cell phone or a radio. It is a known procedure to provide additional switches on the steering wheel, for instance, in the area of the airbag module, for performing such functions. Another suitable location for such switches is the spokes of the steering wheel. The arrangement of a switch within reach of the fingers of the driver when his/her hands are on the steering wheel markedly improves driving safety. 
     The invention serves to make the operation of an above-mentioned switch more comfortable for the driver and thus serves to improve the driving safety. 
     BRIEF SUMMARY OF THE INVENTION 
     According to the invention, a vehicle steering wheel comprises a steering wheel body and at least one electric switch attached to the steering wheel body. The switch, for adaptation to the length of the fingers of a driver, is adjustably attached to the steering wheel body in such a way that it can be displaced by the driver to assume various positions relative to the steering wheel body. The term steering wheel body is used here to refer, for example, to the combination of a steering wheel skeleton with a foam covering that partially or completely surrounds this skeleton. The advantage of the invention is that every driver, depending on his/her hand size and finger length, can individually set the position of the switch comfortably so that he/she can operate it easily without being distracted from traffic. Adjustment of the switch is, of course, not aimed at the adjustment into another functional switch position, in which an actuated switch part has a changed distance to the steering wheel, for instance during switching “On” and “Off”. The adjustment of the switch or switch part according to the invention is rather independent of the functional switch position and the displacement of the switch or switch part does not amend the switching position. Preferably, the complete preassembled switch, as a unit, is displaced for adaptation to the finger length. 
     In order to make the adjustment as convenient as possible, the switch is preferably mounted in such a way that the adjustment can be made by the driver without the use of a tool. In this way, the driver can move the switch into a suitable position at any time. 
     Preferably the switch is accommodated in a linear guide. Advantageously, the steering wheel is designed in such a way that for mounting the switch it can be inserted into the linear guide transversely to the adjustment direction and is then held in the linear guide by being moved subsequently. This design allows a simple installation of the switch on the steering wheel and, at the same time, a reliable guidance of the switch when it is moved. 
     In a preferred embodiment of the invention, a detachable form-fitting connection is provided, which can be locked in any position of the switch. This form-fitting connection is preferably a toothed structure that meshes with counter teeth on the switch. Teeth allow a fine graduation of the various adjustment positions possible while the mechanism is simple and inexpensive to produce. 
     In order to actuate the adjustment mechanism, it is preferably provided that the part of the form-fitting connection that is associated with the switch can be moved transversely to the adjustment direction out of a locked position and into a traversing position in which an adjustment of the switch is permissible, the part of the form-fitting connection associated with the switch being subsequently moved into another locked position. The form-fitting connection can be unlocked, for example, in that the driver depresses an adjustment element and moves the switch, the switch being automatically locked in its new position after the adjustment element has been released. 
     Preferably, the adjustment element is situated on the rear side of the steering wheel and is connected to the switch, so that the switch can be moved by means of the adjustment element. 
     Preferably, a latching pin that forms the switch-side part of the form-fitting connection is formed on the adjustment element. Moreover, the adjustment element can be connected to the switch via a flexible bearing arm, the latching pin being brought out of the locked position and into the traversing position by bending the bearing arm. This construction is simple, space-saving and inexpensive to produce. 
     In a preferred embodiment of the invention, the switch is designed as a multi-function keypad. Such a multi-function keypad makes it possible to operate an unlimited number of functions with just a few switching elements. 
     The production can be even further simplified in that the switch is part of a switching unit configured as a prefabricated assembly having a housing which is rigidly attached to the steering wheel body and in which the switch is movably mounted. The housing can be attached to the steering wheel, for example, by a latching connection so that the assembly merely has to be inserted into the steering wheel body. 
     The switch can be attached to a spoke of the steering wheel body ergonomically and adapted to the design of the steering wheel and it can be configured to move lengthwise along said spoke. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of a spoke of a steering wheel according to the invention; 
     FIG. 2 is a detail of the bottom of a steering wheel according to the invention; 
     FIG. 3 is a schematic view of an assembly with a switch for use in a steering wheel according to the invention; and 
     FIG. 4 is a sectional view of the assembly of FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows a spoke  10  of a steering wheel. The spoke  10  is part of a steering wheel body  12 , in this case comprising a rigid skeleton  14  and a foam covering  16  surrounding the skeleton  14 . However, the steering wheel body  12  can also be made in another manner, since its design is not essential to the principle of the invention. 
     In the spoke  10 , a switching unit  18  is integrated, which is configured as an assembly consisting of a housing  20  and a switch  22  that is mounted movably in the housing  20 . In this example, the switch  22  is a multi-function keypad with buttons  24  (FIG.  3 ), which can be used for any vehicle functions. The switch  22  is connected to a cable  25  that extends out of the housing  20  and that is connected to a vehicle electronic system (not shown here) in order to transmit signals from the buttons  24  of the switch  22  to this electronic system. The part of the cable  25  that runs through the inside of the housing  20  is wound in a spiral shape in order to be able to compensate for the adjustment path of the switch  22 . 
     FIGS. 3 and 4 show the switching unit  18  in greater detail. The housing  20  consists of a bottom part  26  and a cover part  28  which can be closed by a latching connection B to form the housing  20 . Latching elements  27  are formed on the bottom part  26  and they can be used to latch the switching unit  18  to the steering wheel body  12 . 
     The cover part  28  has an opening that is configured in such a way that the switch  22 , which is located in the housing  20  and whose top preferably lies in a plane with the cover part  28 , can be moved into any desired adjustment position. The lengthwise extent of the opening is coordinated with the adjustment path of the switch. For optical reasons and for protection against dirt and damage, panels  44  are situated on the switch  22 . The panels  44  are configured in such a way that they in each case close the part of the opening in the cover part  28  that is not filled by the switch  22 . The panels  44  can also be designed as bellows. 
     The switch  22  has tabs  32  that are accommodated between the bottom of the housing  20  and projections  30  that are formed on the underside of the bottom part  26 . The bottom and the projections  30  form a linear guide in which the switch  22  is movably held. The projections  30  are arranged in the middle area of the bottom part  26  in such a way that the switch  22  can be simply inserted into the housing  20  as will still be described. The switch  22 , regardless of its actual position, is always held by four projections  30 . 
     In the bottom part  26 , there is provided an elongated hole  34  whose lengthwise sides have a toothed structure  36 . The lengthwise extent of the elongated hole  34  is coordinated with the length of the possible adjustment path of the switch  22 . 
     The switch  22  is connected to a flexible bearing arm  38  which, in turn, has an adjustment element  40 . A latching pin  42  is formed on the adjustment element  40 . The latching pin  42  has teeth that create a form-fitting connection with the teeth of the toothed structure  36 , as long as the bearing arm  38  is in a locked position. 
     The adjustment element  40  can be pressed into the housing  20  from above, i.e. transversely to the adjustment path V, as a result of which the latching pin  42  is released from the teeth of the toothed structure  36 . The switch  22  is now brought into a traversing position. On the adjustment element  40 , the switch  22  can be moved in the housing  20  until it reaches the desired position. When the adjustment element  40  is released, the bearing arm  38 , due to its intrinsic elasticity, moves back into its initial position, the teeth of the latching pin  42  engaging the toothed structure  36  in a different place, thereby once again locking the switch  22 . In order to ensure a defined vertical position of the adjustment element  40 , a stop  45  made up of two lateral projections is provided on the latching pin  42  above the two latching teeth and projecting laterally beyond them, said stop  45  being in contact with the top of the bottom part  26  in the locked position. 
     The assembly of the switching unit  18  is simple and quick. First of all, the switching unit  18  is put together. For this purpose, in a first step, the switch  22  is put in place at one end of the bottom part  26 . As can be seen in FIG. 3, the projections  30  and the tabs  32  are adapted to each other in such a way that the tabs  32  can first be guided past the projections, transversely to the adjustment direction, and can subsequently be slid between the bottom part  26  and the projections  30 . 
     After the switch  22  has been arranged in its linear guide, the bearing arm  38  is attached to the switch  22 , for example, by means of a screw. Then the switch  22  has to be slid once more onto the housing end with the elongated hole  34  at whose end there is a widened section  46 . The latching pin  42  passes through the widened section  46 , thus reaching the inside of the housing. Then the switch  22  is slid back to the middle of the housing, the latching pin  42  latching in the toothed structure  36  and affixing the switch  22  in the housing  20 . Subsequently, the cover part  28  is placed onto the bottom part  26  and is latched to the latter in order to close the housing  20 . 
     The prefabricated switching unit  18  can now be simply attached to the steering wheel body  12  in that it is inserted into a recess that is provided on the steering wheel body and is securely connected to the steering wheel body  12  by means of the latching elements  27 . 
     As can be seen in FIG. 1, the foam covering  16  has an opening  48  through which the adjustment element  40  protrudes. The lengthwise extension of this opening  48  corresponds essentially to the maximum adjustment path of the switch  22 . 
     A driver who grasps the steering wheel can grip the rear of the spoke  10  with one finger and can press the adjustment element  40  into the spoke. Now he/she can move the switch  22  to the desired position. As soon as the driver lets go of the adjustment element  40 , the switch  22  latches into its new position.