Abstract:
The invention relates to a vehicle steering wheel comprising a steering wheel body and a gas bag module provided with two or more guide pins. The gas bag module, for actuation of a horn, is displaceably mounted in an axial direction by means of the guide pins. The steering wheel further comprises at least one multifunctional switch unit for the remote actuation of specific vehicle functions. The at least one multifunctional switch unit is mounted on the guide pins of the gas bag module so as to be movable in the axial direction independently of the gas bag module.

Description:
TECHNICAL FIELD 
     The invention relates to a vehicle steering wheel. 
     BACKGROUND OF THE INVENTION 
     Known vehicle steering wheels comprise a steering wheel body, a gas bag module provided with two or more guide pins, the gas bag module for actuation of a horn being displaceably mounted in an axial direction by means of the guide pins, and at least one multifunctional switch unit for the remote actuation of specific vehicle functions. A majority of such vehicle steering wheels which have been used in the meantime has a so-called floating horn gas bag module. This is a module mounted on the steering wheel body so as to be movable in the axial direction (axial direction means in the direction of the steering shaft), which is displaced for actuation of the horn. Alongside the module, multifunctional switch units are to be found increasingly frequently, which are likewise mounted on the steering wheel body or on the module. As through the actuation of the multifunctional switch a force is exerted onto the switch unit and the latter is arranged close to the module, it must be avoided that with the multifunctional switch actuation, an actuation of the horn occurs inadvertently. Vehicle functions which are operated remotely by the multifunctional switches are, for example, the speedomat, radio, telephone and the like, but not the horn, which is in fact to be triggered by pressing down the module. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention provides a vehicle steering wheel in which the multifunctional switch unit and the gas bag module are uncoupled with regard to movement in a simple manner so that an inadvertent actuation of the horn on utilization of the multifunctional switch can be ruled out. This is achieved in a vehicle steering wheel which comprises a steering wheel body and a gas bag module provided with two or more guide pins. The gas bag module, for actuation of a horn, is mounted displaceably in an axial direction by means of the guide pins. The steering wheel further comprises at least one multifunctional switch unit for the remote actuation of specific vehicle functions. The at least one multifunctional switch unit is mounted on the guide pins of the gas bag module so as to be movable in the axial direction independently of, i.e. uncoupled from the gas bag module. Thus, according to the invention the guide pins of the module are themselves used for fastening the multifunctional switch unit, so that the guide pins have a dual function. A positive side-effect here is that the gap between the module and the multifunctional switch unit adjoining it can be kept constant and small. In a vehicle steering wheel according to the invention, therefore, no great structural effort is to be made for the uncoupling of the multifunctional switch unit and the gas bag module. 
     According to the preferred embodiment, the module and the multifunctional switch unit form a preassembled unit and can, therefore, be fastened as a unit to the steering wheel body, which keeps the positional tolerances small. 
     The preassembled unit is preferably formed in that the module and the multifunctional switch unit are connected with each other via the guide pins, whereby hitherto required support sheets for the preassembled unit can be completely dispensed with. 
     If the guide pins are also moved on actuation of the module, the position of the multifunctional switch unit can be established by a spring, so that also a defined friction between the guide pins and the multifunctional switch unit can not lead to the moving of the module or of the multifunctional switch unit, depending on which of the two parts is actuated. The spring is in fact arranged such that it presses the multifunctional switch unit into its mounting position. 
     For this, the springs are preferably arranged between the module and the multifunctional switch unit, the spring being able to serve, at the same time, for restoring the module after completion of the horn actuation. 
     An embodiment makes provision that the guide pins are fastened in the module and have a stop provided remotely from the fastening in the gas bag module. Between the module and the stop, the multifunctional switch unit is then displaceably mounted on the guide pins, so that without further structural effort the multifunctional switch unit is prevented from detaching itself from the module when both parts are still forming a preassembled unit, i.e. are not yet fastened to the steering wheel body. 
     It is also conceivable that bearing bushes are arranged on the guide pins, which bearing bushes are pressed into receptacles in the steering wheel body during mounting the preassembled unit into position, so that bearing bushes do not even have to be mounted in the steering wheel body before the installation of the unit. Preferably, the bearing bushes are pressed into a region of the steering wheel body which is encased in foam, which ensures a defined flexibility of the mounting. The bearing bushes can also be formed by the multifunctional switch unit itself. 
     Particularly when the bearing bushes are pressed into a foamed region, the entire unit must be prevented from being able to be easily removed again from the steering wheel body. For this, a snap connection can be used between the module and the steering wheel body, which at the same time can serve as an axial stop of the module. This means that the snap connection also defines the stop in the basic position with the horn not being actuated. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a top view onto a vehicle steering wheel according to the invention, 
     FIG. 2 shows a sectional view through the preassembled unit of FIG. 1, consisting of a module, a multifunctional switch unit and guide pins, 
     FIG. 3 shows a section through the vehicle steering wheel with the unit of FIG. 2 installed and the horn being not actuated, and 
     FIG. 4 shows a section according to FIG. 3, with the horn actuated. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In FIG. 1 a vehicle steering wheel is illustrated, which has a steering wheel body  10 , a gas bag module  12  and multifunctional switch units  14  on the sides immediately adjoining the gas bag module  12 , for actuation of vehicle functions such as radio, telephone, on-board computer and the like. The steering wheel consists of a steering wheel skeleton  16  which is only illustrated in part, and of a foam casing  18 . The gas bag module  12  is mounted on the steering wheel body  10  so as to be movable in the axial direction, i.e. in FIG. 1 in the direction perpendicular to the plane of the drawing, so that by pressing and moving the gas bag module  12 , a horn contact on the rear face of the module is closed and the horn sounds. 
     The gas bag module  12  and the two multifunctional switch units  14  sit so close to each other that only a small gap  20  is formed between these parts. In addition, the gas bag module  12  and the multifunctional switch units  14  form a preassembled unit, closed in itself, which in the state shown in FIG. 2 is placed in complete form onto the steering wheel body  10  and is mounted on it. 
     In FIG. 2 it is to be seen that the gas bag module has a covering cap  22  of plastic, projecting from which on the rear face on each side, adjoining the multifunctional switch unit, are sleeve-shaped projections  24 . The guide pins  26  for the axial mounting of the gas bag module  12  are pressed into these sleeve-shaped projections  24 . The guide pins  26  have at their free end, which is not pressed in, a laterally protruding collar which acts as a stop  28  as long as the module is not installed into the steering wheel, i.e. after assembling the module. Arranged on the guide pins  26 , adjoining the stop  28 , are plastic bearing bushes  30  which have radially outer annular extensions  32 . Arranged in addition on the guide pins, between the projections  24  and the bearing bushes  30 , are ear-like projections  34  of the housing  36  of the multifunctional switch unit  14 , compression springs  38  and bearing rings  40  for the springs  38 . A cup-shaped holding piece  41  to receive the module  12  can be optionally fastened on the bearing rings  40 . The guide pins  26  can also be constructed in one piece with the holding piece  41 . 
     Through the fact that the guide pins  26  are pressed into the projections  24  and that these pins, by means of annular shoulders  42  on their outer periphery, are also prevented in a form-fitting manner from leaving the projections  24 , every two guide pins  26  associated with one multifunctional switch unit  14 , hold the multifunctional switch units  14  on the module  12  to form the preassembled unit. 
     The springs  38  are arranged with regard to their action between the pressed-in end of the pins  26  and hence between the module and the multifunctional switch unit  14 , and press the multifunctional switch units  14  into the subsequent mounting position, i.e. downwards. Nevertheless, owing to the displaceability of multifunctional switch units  14  and of the module  12  in relation to each other, the multifunctional switch units and the module are uncoupled in axial direction with regard to movement. In radial direction, on the other hand, the multifunctional switch units  14  and the module  12  are firmly connected with each other via the guide pins  26 , so that only a small gap  20  results, which is also always constant irrespective of the axial position of the multifunctional units  14  and the module  12  with respect to each other, because these parts are arranged on the same guide. 
     As can be seen, the preassembled unit illustrated in FIG. 2 does not have any support sheets or the like, and the unit also does not necessarily have to be mounted onto a fixed support sheet on the steering wheel body  10 . 
     For the installation itself, the unit shown in FIG. 2 is pressed from above downwards onto the steering wheel body  10 . Receptacles  43  for the guide pins  26  together with their bearing bushes  30  are formed in the foam casing. Recesses complementary to the bead  32  are likewise present, in order to achieve, after the pressing in, a form fit between the bearing bushes  30  and the surrounding foam  18 . Projecting from the underside of the module are snap hooks  45 , which on installation pass through openings  44  in the hub of the steering wheel skeleton  16  and then latch into place, so that a snap connection is formed (see FIG.  3 ). The snap hooks  45  form, at the same time, an axial stop for the module, because the springs endeavor to press the module upwards. So that—for the initial position shown in FIG. 3, in which no horn actuation is yet present—the snap hooks  45  also act as axial stops for the module, the stops  28 , contrary to the non-installed situation in FIG. 2, are spaced apart axially from the bearing bushes  30 . The springs  38  not only press the module  12  upwards, but they also press the multifunctional switch units  14  downwards into the mounted final position, in which the multifunctional switch units lie against the bearing bushes  30  and/or the steering wheel body  10 . 
     Through this defined position of the multifunctional switch units  14 , even on application of a downwardly-directed pressure onto the multifunctional switch units  14 , with regard to FIG. 3, an inadvertent contacting of the horn contacts  52 ,  54  can not occur. 
     On pressing of the module  12  downwards to actuate the horn, the module  12  must be pressed downwards against the force of the springs  38  (see FIG.  4 ). The springs  38  also serve to restore the module into the initial position shown in FIG. 3, so that on the rear face of the module, apart from the guide pins  26  and the hooks  45 , no hitherto usual receptacles have to be provided for the mounting of restoring springs. Therefore, the axial overall space can also be kept small. 
     After the installation of the module and of the multifunctional switch unit, the stop  28  does not necessarily have to be present in the steering wheel. Also, up until installation, it would be conceivable to manage without the stop  28 . For example, the springs  38  could hold the gas bag module and the multifunctional switch unit against each other. 
     Alternatively, the bearing bushes  30  could also be formed by the multifunctional switch unit. 
     On the other hand, with a steering wheel without gas bag module, the snap connection could be readily omitted, so that its characteristics are only achieved by the stop  28 .