Abstract:
The invention relates to a module ( 1 ) for an occupant-protection device of a motor vehicle. Said module containing a functional element ( 2 ), which can be activated if the motor vehicle is involved in a collision and which comprises an electrically conductive material and a fixing device ( 3 ) mechanically fixing the functional element ( 2 ) to the bodywork of the motor vehicle. According to the invention, the functional element ( 2 ) is electrically insulated in relation to the bodywork of the motor vehicle. According to the invention, the functional element ( 2 ) is electrically insulated in relation to the bodywork of the motor vehicle. This guarantees that the functional element, which can be activated in a collision, cannot electrically interact with the bodywork of the motor vehicle, is particular in the form of a voltage surge. The invention permits the reliability of a module for an occupant-protection device of a motor vehicle to be increased and prevents potential malfunctions in a simple manner.

Description:
DESCRIPTION  
       [0001]     The invention relates to a module for a vehicle occupant protection device of a motor vehicle as claimed in the preamble of claim  1 .  
         [0002]     Such a module comprises a functional element which can be activated in the event of the motor vehicle crashing and which has an electrically conductive material and a securing device for mechanically securing the functional element to the bodywork of the motor vehicle.  
         [0003]     The vehicle occupant protection device may be designed here in the form of an airbag device. The functional element is then the gas generator which is assigned to the airbag.  
         [0004]     It is also conceivable for the vehicle occupant protection device to be formed as a seatbelt pretensioning device for pretensioning a seatbelt in the event of the motor vehicle crashing. The functional element is formed here in particular as a pyrotechnic device for making available the movement which is required for the function of pretensioning the belt.  
         [0005]     The modules of the generic type which are known from the prior art have the disadvantage that in the event of an electrical failure a potential and/or a voltage surge starting from the bodywork of the motor vehicle interacts with the functional element via the securing device. This can lead to a situation in which an undesired or indefinable state of the activatable functional element occurs. This results in a situation in which a malfunction of the vehicle occupant protection device is detected in the electronic monitoring system of the vehicle occupant protection device.  
         [0006]     In an extreme case it is also conceivable for the functional element to be triggered unintentionally.  
         [0007]     The present invention is therefore based on the object of making available a module for a vehicle occupant protection device of a motor vehicle which is easily and cost-effectively protected against a malfunction.  
         [0008]     This object is achieved by means of a module having the features of claim  1 .  
         [0009]     According to the invention there is provision for the functional element to be electrically insulated from the bodywork of the motor vehicle.  
         [0010]     This ensures that the activatable functional element is isolated from an electrical interaction with the bodywork of the motor vehicle, in particular in the form of a voltage surge. As a result, the reliability of a module for a vehicle occupant protection device of a motor vehicle can easily be increased and possible malfunctions can be avoided.  
         [0011]     In particular if the functional element has an electrical trigger device for activating the functional element in the event of a crash, the electrical trigger device is thus isolated from an electrical interaction with the bodywork of the motor vehicle.  
         [0012]     In one preferred embodiment of the module, the functional element is electrically insulated from the bodywork of the motor vehicle by means of an electrically non-conductive securing device. For this purpose, the securing device is fabricated, at least in certain sections, from an electrically non-conductive material.  
         [0013]     The module advantageously has separate insulating means which electrically insulate the functional element from the bodywork of the motor vehicle. All electrically non-conductive materials such as, for example, paper, cardboard, textiles, non-conductive plastics and surface coatings and non-conductive plastic film material are suitable for use as separate insulating means.  
         [0014]     The separate insulating means are preferably arranged here in such a way that the functional element is electrically insulated from the securing device and/or the securing device is electrically insulated from the bodywork of the vehicle.  
         [0015]     One preferred embodiment is characterized in that the insulating means are provided as electrically insulating materials on the functional element, at least in the regions of the functional element which are in mechanical contact with the securing device. For this purpose, the insulating means may be, for example, in the form of plastic layers or surface coating layers which are applied in a non-detachable fashion to the surface of the functional element.  
         [0016]     The securing device of the module is preferably embodied in a plurality of parts. In particular, it has a holding device for receiving the functional element and a mounting device which can be mechanically secured to the holding device, for mechanically securing the mounting device to the bodywork of the motor vehicle.  
         [0017]     In this context, the insulating means are preferably formed in such a way that they electrically insulate the functional element from the holding device and/or the holding device from the mounting device and/or the mounting device from the bodywork of the motor vehicle.  
         [0018]     In one preferred embodiment, the holding device is designed to receive an essentially cylindrical functional element. The cylindrical functional element may be a gas generator. In this context, the insulating means preferably have a hollow cylindrical insulating element which can be arranged between the essentially cylindrical functional element and the holding device. This ensures the electrical isolating between the functional element and the holding device.  
         [0019]     In one preferred embodiment, the holding device of the functional element has a flange, directed away from the functional element, which serves for attaching the holding device to the mounting device.  
         [0020]     In order to mechanically secure the holding device to the mounting device, the flange of the holding device can have attachment means.  
         [0021]     It is also conceivable for the flange of the holding device to be capable of being mechanically secured to the mounting device by means of separate attachment means. In this context, the flange preferably has a plurality of holes for feeding through the attachment means, the mounting device comprising correspondingly arranged holes.  
         [0022]     Furthermore, a rail which can be fitted onto the flange and has non-detachable or detachable attachment elements, arranged at a distance from the holes of the flange, preferably serves as attachment means for securing the holding device to the mounting device. The attachment elements can be embodied here, for example, as screws, rivets or latching elements.  
         [0023]     Such a module preferably has, as insulating means, an insulating rail for providing electrical insulation between the attachment means and the holding device. For this purpose, the insulating rail is formed, for example, as an element which extends between the rail which can be fitted on and the flange of the holding device, the insulating rail in the region of the holes for the attachment elements engaging in the holes of the holding device and/or in the holes of the mounting device in such a way that the attachment elements are electrically insulated from the holding device and/or from the mounting device.  
         [0024]     Alternatively, the insulating rail may be formed as an element which extends between the mounting device and the flange of the holding device, the insulating rail, again in the region of the holes for the attachment elements, engaging in the holes of the mounting device and/or in the holes of the holding device in such a way that the attachment elements are electrically insulated from the holding device.  
         [0025]     In one preferred use of the module for an airbag device, a section of the airbag is arranged between the flange of the holding device and the rail which can be fitted on and/or between the flange of the holding device and the mounting device. In this context, holes for feeding through the attachment elements are provided in the sections of the airbag. In this way, the sections of the airbag which are arranged on the flange of the holding device serve simultaneously as additional insulating means which electrically isolates the holding device from the mounting device.  
         [0026]     The module according to the invention is preferably intended for use in an airbag unit of a vehicle occupant protection device, the functional element being formed as a gas generator.  
         [0027]     The module according to the invention can also be provided for use in an electrically triggerable seatbelt pretensioning device of a seatbelt. In this context, the functional element is provided in particular as a pyrotechnic device which ensures the movement of the seatbelt which is necessary to pretension the seatbelt. 
     
    
       [0028]     Further features and advantages of the invention are explained by reference to the exemplary embodiments of the module according to the invention which are explained in the figures. In the drawing:  
         [0029]      FIG. 1   a  shows a perspective view of the individual components of a first embodiment of a module with a functional element which is formed as a gas generator;  
         [0030]      FIG. 1   b  shows a module in the view in  FIG. 1   a  with a gas generator mounted and additional insulating means;  
         [0031]      FIG. 2  shows a cross section through a holding device with insulating means;  
         [0032]      FIG. 3  shows a perspective view of a second embodiment of a module with a functional element which is formed as a gas generator;  
         [0033]      FIG. 4  shows a perspective view of a third embodiment of a module with a functional element which is formed as a gas generator;  
         [0034]      FIG. 5   a  shows a perspective view of a fourth embodiment of a module with a functional element which is formed as a gas generator, and insulating means for the attachment rail, and  
         [0035]      FIG. 5   b  shows a module in the view in  FIG. 5   a  with insulating means arranged on the attachment rail. 
     
    
       [0036]      FIG. 1   a  shows a first embodiment of a module  1  with a functional element which is formed as a gas generator  2 , in a perspective view, and components which are separated in terms of perspective for the sake of clarity.  
         [0037]     The gas generator  2  which is formed so as to be essentially cylindrical has, at one of its ends, an electrically controlled trigger device  20 , and it can be arranged in an insulating element  40  which is formed so as to be hollow cylindrical. This insulating element  40  completely engages around the outer surface  21  of the cylindrical gas generator as a separate insulating means. The insulating element  40  can be positioned in a holding device  30 , the outer surface of the insulating element  40  being in mechanical contact with the holding device  30 , at least in certain sections. The outer surface  21  which is formed so as to be electrically conductive at least in certain sections is electrically insulated here from the holding device  30  by the insulating element  40 .  
         [0038]     The hollow cylindrical insulating element is fabricated here from electrically insulating material, for example plastic, rubber, paper, cardboard, textiles or leather. In the embodiment illustrated in  FIG. 1 , the holding device  30  forms, together with a mounting device  31 , the securing device  3  which serves to mechanically secure the gas generator  2  to the bodywork of a motor vehicle. For this purpose, the holding device  30  has a flange  32 , directed away from the insulating element  40 , and holes  34 . Separate attachment means  33  can be arranged on the flange  32  in order to secure the holding device  30  to the mounting device  31 .  
         [0039]     For this purpose, the separate attachment means  33  have a rail  330  which extends in the length of the flange  32 , can be fitted onto the flange and has attachment elements  331  which are arranged on the rail. The attachment elements  331  which are arranged with the spacing of the holes on the rail  330  can be lead through the holes  34  of the flange  32  and through holes  34 ′ in the mounting device which correspond to them, in order to secure the holding device  30  mechanically to the mounting device  31 .  
         [0040]     The attachment elements  331  can be formed here either as detachable or non-detachable connecting means in the form of screws, rivets or latching elements.  
         [0041]     The mounting device  31  can have a plurality of forms corresponding to the geometric peripheral conditions present in the motor vehicle.  
         [0042]     In the embodiment illustrated in  FIGS. 1   a  to  5   a , the mounting device  31  has the same form in each case. A receiving section  37  in the form of a half shell is provided for receiving the essentially cylindrical holding device  30 , the flange  32  coming to rest flush with a corresponding attachment section with the holes  34 ′ of the mounting device  31 .  
         [0043]     Furthermore, the mounting device has a plurality of attachment sections which are designed, for example, in the form of attachment hooks  35  or attachment feet  36 . In order to secure the mounting device  31  mechanically to the bodywork of a motor vehicle, the attachment hooks  35  are hooked into assigned reciprocals in the bodywork. The attachment feet  36  have holes for feeding through further separate attachment means, for example in the form of screws or rivets for detachably or non-detachably securing the attachment foot  36  to the bodywork of the vehicle.  
         [0044]      FIG. 1   b  shows the module from  FIG. 1   a , the hollow cylindrical insulating element  40  being arranged, together with the gas generator  2 , in the interior of the holding device  30 . Identical components are provided here with identical reference symbols.  
         [0045]     In addition to the hollow cylindrical insulating element  40 , further insulating means for providing electrical insulation between the gas generator  2  and the bodywork of a motor vehicle are illustrated in  FIG. 1   b.    
         [0046]     An insulating rail  41  may be provided on the mounting device  31  in the region of the holes  34 ′. This insulating rail  41  extends essentially along the mounting region of the flange  32  of the holding device  30 . In this context, it has essentially hollow cylindrical elements in the sections of the holes  34 ′, which elements engage through the holes  34 ′ of the mounting device  31  and the holes  34  of a mounted holding device  30 . These hollow cylindrical elements of the insulating rail  41  are, like the insulating rail itself, fabricated from electrically insulating material, for example plastic, rubber, paper, cardboard, textiles or leather. The insulating rail  41  thus prevents direct mechanical and thus electrical contact between the attachment elements  331  of the separate attachment means  33  and the mounting device  31 .  
         [0047]     Furthermore it is advantageous to use the airbag of an airbag device which is usually manufactured from an electrically non-conductive textile material as insulating means for providing electrical insulation between the gas generator  2  and the bodywork of a motor vehicle.  
         [0048]     For this purpose, an airbag section  42 ,  42 ′ with correspondingly arranged holes  34 ′″ may be respectively provided between the rail  330 —which can be fitted on—of the separate attachment means  33  and the flange  32  of the holding device  30  and between the flange  32  of the holding device  30  and the mounting device  31 , for the purpose of feeding through the attachment elements  331 .  
         [0049]     These airbag sections  42 ,  42 ′ are usually arranged in the edge region of an airbag in such a way that the gas generator  2  is located in the interior of an airbag.  
         [0050]     In  FIG. 1   b , only the sections  42 ,  42 ′ of the airbag are illustrated for the sake of clarity. In this way, the airbag which is present in any case in an airbag module can be used as an insulating means in the sense of the invention.  
         [0051]      FIG. 2  shows a cross section through a holding device  30  of an essentially cylindrical functional element  2 , for example in the form of a gas generator. In a way which is similar to the holding devices  30  shown in  FIGS. 1   a  and  1   b , the holding device  30  has a flange  32  directed away from the functional element  2 . An essentially hollow cylindrical insulating element  40  is arranged between the functional element  2  and the holding device  30 . This insulating element  40  can be manufactured, on the one hand, as a separate component from one of the electrically insulating materials mentioned above. On the other hand, it is also conceivable to provide the sections of the holding device  30  which are in mechanical contact with the functional element  2  with an electrically insulating layer in the form of a surface coating or rubber. Correspondingly, the sections of the functional element which are in mechanical contact with the holding device  30  can also be provided with such a layer.  
         [0052]      FIG. 3  shows a further embodiment of the module from  FIG. 1   b . In contrast to the module in  FIG. 1   b , there is no insulating rail  41  arranged as insulating means on the mounting device  31 . In the variant shown, the mounting device  31  is provided with insulating shoes  43 , on the attachment hooks  35  and mounting feet  36  which are in mechanical contact with the bodywork of a motor vehicle, in such a way that the mounting device  31 , and thus also the gas generator which is secured to it by means of the holding device  30 , is electrically insulated from the bodywork of the vehicle. For this purpose, the insulating shoes  43  engage around the attachment hooks  35  and the mounting feet  36  at least in the regions which are in contact with the bodywork of the vehicle when the mounting device  31  is attached.  
         [0053]     The insulating shoes  43  can in turn be manufactured from any of the electrically insulating materials mentioned above. A particularly advantageous variant provides for the insulating shoes  43  to be integrally attached through injection molding with an electrically insulating plastic. In addition, the insulating shoes  43  can serve for damping the oscillations of the securing device  3  given suitable elasticity.  
         [0054]      FIG. 4  shows a further embodiment of the module in  FIG. 1   b . In contrast to the module in  FIG. 1   b , an insulating rail  41  is provided between the rail  330 —which can be fitted on—of the separate attachment means  33  and the flange  32  of the holding device  30 . This insulating rail  41  also has essentially hollow cylindrically shaped elements in the region of the holes  34 , which elements engage through the holes  34  of the holding device  30  and the holes  34 ′ of the mounting device  31  in the mounted position. This prevents electrically conductive mechanical contact between the attachment elements  331  and the flange  32  of the holding device  30 . At least the airbag section  42 ′ which is to be arranged between the flange  32  and the mounting device  31  is absolutely necessary to provide electrical insulation between these two elements.  
         [0055]      FIG. 5   a  and  FIG. 5   b  show a further variant of an insulating rail  41  according to the embodiment from  FIG. 4 . The insulating rail  41  can be arranged here along the rail  330 —which can be fitted on—of the separate attachment means  33 . Said rail is arranged on the surface facing the flange  32  of the holding device  30  during mounting, and has hollow cylindrical elements which engage around the attachment elements  331  in such a way that in the mounted position of the attachment elements  331  there is no electrically conductive contact between the attachment elements  331  and the flange  32  of the holding device  30  and/or the mounting device  31 . In this embodiment also, at least the airbag section  42 ′ which is to be arranged between the flange  32  and the mounting device  31  is absolutely necessary for providing electrical insulation between these two elements.  
         [0056]     The various insulating means  40 ,  41 ,  42 ,  42 ′,  43  which are shown in  FIGS. 1   a  to  5   b  can be used in different combinations. The central feature in each case is exclusively the fact that the insulating means act in such a way that the flow of electrical direct current or alternating current between the functional element  2  and the bodywork of a motor vehicle is reliably prevented.  
         [0057]     In addition to the embodiments shown in  FIGS. 1   a  to  5   b , it is also conceivable for the electrical insulation between the functional element  2  and the bodywork of a motor vehicle to be ensured by virtue of the fact that the securing device  3  is manufactured at least in certain sections from an electrically non-conductive material, for example a suitable plastic. With respect to the embodiment of the holding device  30  and mounting device  31  forming the securing device  3  which is shown in  FIGS. 1   a  to  5   b  it is possible, in order to bring about the electrical insulation of the functional element  2 , to manufacture the holding device  30  and/or the mounting device  31  from an electrically non-conductive material.  
                                         List of reference numbers                                 1   Module        2   Functional element, gas generator        3   Securing device        20   Electrical trigger device        21   Outer surface of gas generator        30   Holding device        31   Mounting device        32   Flange of holding device        33   Separate attachment means       34, 34″, 34′ ″   Holes        35   Attachment hooks        36   Attachment feet        37   Receiving section        40   Hollow cylindrical insulating element        41   Insulating rail       42, 42′   Airbag section        43   Insulating shoes       330   Rail which can be fitted on       331   Attachment elements