Abstract:
An airbag device includes an airbag module and at least one airbag cover which is connected to a piston via pulling devices. The piston can be subjected to pyrotechnical action in order to produce a linear movement of the piston. When the piston is caused to move, the airbag cover moves from a closed position, in which the airbag cover blocks an exit path of the airbag out of the airbag module, into an open position, in which the airbag cover clears the exit path of the airbag out of the airbag module. The piston is forcibly guided to perform a helical movement so that the piston, when caused to move, performs a rotational movement during its linear movement, thus winding up the pulling devices. A method for operating an airbag device is also provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
         [0001]    This application is a continuation of copending International Application No. PCT/DE01/01379, filed Apr. 9, 2001, which designated the United States and was not published in English.  
         BACKGROUND OF THE INVENTION  
       Field of the Invention  
         [0002]    The invention relates to an airbag device and to a method of operating an airbag device.  
           [0003]    Published, Non-Prosecuted German Patent Application Nos. DE 197 26 878.1 and DE 197 33 896.8, European Patent Application No. EP 0 867 346 A1, and International Publication No. WO 99/61288 disclose conventional airbag devices and methods of triggering or operating such airbag devices.  
         SUMMARY OF THE INVENTION  
         [0004]    It is an object of the invention to provide an improved airbag device and a method of operating or triggering an airbag device.  
           [0005]    It is in particular an object of the invention to provide a space-saving construction for an airbag device and an operating method for such a construction. The present invention can be employed as a supplement to the subject matter of the above-mentioned patent applications, and, in an advantageous manner, can further reduce the so-called “aggressiveness” of the airbag in that a mechanism pulls the airbag cover into the dashboard.  
           [0006]    The present invention relates in particular to improvements of airbag systems and exemplary embodiments dealt with in the above-mentioned patent applications, especially as regards the construction of the airbag device and the triggering/operating control system and, specifically, to a device and a method for controlling an airbag flap or airbag cover. The disclosure of the above-mentioned patent applications especially as regards the construction of the airbag device and the triggering/operating control system and, specifically, the embodiments for controlling an airbag flap are incorporated by reference into the present application.  
           [0007]    With the foregoing and other objects in view there is provided, in accordance with the invention, an airbag device, including:  
           [0008]    an airbag module defining an airbag exit path, the airbag module including a piston, the piston being configured to be subjected to a pyrotechnical action such that the piston performs a linear movement when being acted upon;  
           [0009]    pulling devices;  
           [0010]    at least one airbag cover connected to the piston via the pulling devices, the at least one airbag cover being movable from a closed position into an open position when the piston is acted upon, the at least one airbag cover, when in the closed position blocking the airbag exit path, and the at least one airbag cover, when in the open position, clearing the airbag exit path; and  
           [0011]    a helical positive guide for guiding the piston such that the piston, when being acted upon and performing the linear movement, also performs a rotational movement for winding up the pulling devices.  
           [0012]    In other words, the invention provides an airbag device with an airbag module and at least one airbag cover, which is connected to a piston through the use of pulling devices, which piston can be subjected to pyrotechnical action in order to produce a linear movement, and, when the piston is acted upon, the airbag cover moves out of a closed position, in which it blocks an exit path of an airbag out of the airbag module, into an open position, in which it clears the exit path of the airbag out of the airbag module, a helical positive guide being provided for the piston, and the pulling devices being configured in the form of cables, so that, due to the action upon it, the piston performs a rotational movement during its linear movement, winding up the pulling devices as it does so.  
           [0013]    This is a particularly advantageous way of using a linear actuation of the piston, which can be achieved easily, reliably and economically, and combining it with a space-saving way of winding up the pulling devices.  
           [0014]    Preferably, the positive guide is formed by at least one guideway along the path of movement of the piston, which piston has at least one extension, which rests against the guideway or engages in the guideway. In this configuration, the at least one extension can be formed by a bolt or a screw. It is also possible for two extensions, spaced apart in the direction of its linear motion, to be provided on the piston, and for a guideway to be assigned to each of these two extensions. In this configuration, it is particularly preferred if the pulling devices engage on the piston through the use of the extensions of the piston.  
           [0015]    It is furthermore preferred if the pulling devices include at least one wire, cable or strap, through the use of which the airbag cover is connected to the piston. In this configuration, provision is preferably made for the cable or the wire to be composed of metal, or for the strap to be composed of a textile material or plastic or a mixture thereof.  
           [0016]    According to further preferred embodiments of the invention, the piston is placed in a cup-like manner over a gas generator of the airbag module and/or the piston is guided in a housing of the airbag module, in particular, if appropriate, the piston is guided by a housing of the gas generator.  
           [0017]    The guideway preferably includes a control edge or a slotted guideway.  
           [0018]    With the objects of the invention in view there is also provided, a method of operating an airbag device, the method includes the steps of:  
           [0019]    providing an airbag module having a piston;  
           [0020]    providing at least one airbag cover connected to the piston via pulling devices; and  
           [0021]    subjecting the piston to a pyrotechnical action such that the piston performs a helical movement for winding up the pulling devices such that the pulling devices pull on the at least one airbag cover and move the at least one airbag cover from a closed position blocking an airbag exit path into an open position clearing the airbag exit path.  
           [0022]    In other words, the object of the invention is furthermore achieved by an operating method for an airbag device, wherein at least one airbag cover is moved out of a closed position, in which it blocks an exit path of an airbag out of the airbag module, into an open position, in which it clears the exit path of the airbag out of the airbag module, through the use of pulling devices, by a piston, which is subjected to pyrotechnical action in order to produce a linear movement, and, due to the action upon it, the piston performs a helical or screw-like movement, winding up the pulling devices as it does so, so that the pulling devices pull the airbag cover and move it from the closed position to the open position.  
           [0023]    Other features which are considered as characteristic for the invention are set forth in the appended claims.  
           [0024]    Although the invention is illustrated and described herein as embodied in an airbag device and a method of operating an airbag device, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.  
           [0025]    The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]    FIGS.  1  to  5  are diagrammatic sectional views of a first exemplary embodiment of the invention with a number of variants in accordance with a first aspect of the invention; and  
         [0027]    FIGS.  6  to  11  are diagrammatic sectional views of a second exemplary embodiment of the invention with a number of variants in accordance with a second aspect of the invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]    The same reference numerals in the individual figures of the drawings denote the same or similar components or components with the same or a similar action. The illustrations in the drawings also show and explain features that are not provided with reference numerals, irrespective of whether such features are described below. On the other hand, features that are contained in the present description but are not visible or shown in the drawing will be readily understood by a person of skill in the art.  
         [0029]    Referring now to the figures of the drawings in detail and first, particularly, to FIG. 1 thereof, there is shown a schematic cross section through a dashboard  1  with an airbag cover  2  that can be opened easily. The airbag cover  2  is plugged or clipped at the top and bottom into the dashboard  1  surrounding it. Cables  3  are attached to the airbag cover  2  as pulling devices (preferably one cable at each of the two lateral ends of the airbag cover  2 ). These cables  3  are secured on a piston  5  (shown in FIG. 2) through the use of respective screwed joints  4 . FIG. 1 also shows an airbag  6  of the airbag-module housing  7 , the airbag advantageously being folded “softly,” the bodywork (car body)  8  and an airbag module  9 . The position of the airbag cover  2  is shown before and after a crash, i.e. before and after a triggering of the airbag device A. The airbag cover  2  is shown in a closed position S and in an open position O, wherein the open position O of the cover  2  is illustrated with dashed lines.  
         [0030]    [0030]FIG. 2 shows a section through the airbag module  9  perpendicular to FIG. 1. The parts that are nested into one another, such as the ignition cartridge  10 , the gas generator  11 , the piston  5 , the gas throughflow holes  12  for the actuation of the piston  5  (at one end) and the gas throughflow holes  13  for the airbag  6  are illustrated such that the properties and function of these elements can understood by this illustration alone. The cables  3  are secured on the piston  5  through the use of screws  14 . Distance rings  15  ensure mobility of the piston  5  in the housing  16 . A gas generator housing  16  and the gas generator  11  are preferably provided with covers  17  and  18 .  
         [0031]    [0031]FIG. 3 shows cable fastenings  19  on the airbag cover  2  in a side view of the airbag module  9 . Guideways  20  in the form of slotted guideways are formed in the gas generator housing  16 . In the event of a crash, the piston  5  must thus move forward in a positively guided manner like a screw (helically) in the guideways  20  with the screws  14 , driven by the gas blast of the gas generator  11  through the gas throughflow holes  12 . In addition to their “longitudinal movement” in accordance with the linear component of motion of the piston  5 , the cables  3  therefore also perform a lateral angular motion in accordance with the rotational movement of the piston  5 , as indicated in dash-dotted lines. This simple technique is useful particularly when, for example, small airbag covers  2  are embodied merely as separate parts that can be detached easily.  
         [0032]    For the purpose of further illustration, FIG. 4 is a sectional view at the level of the screwed joint  4 . This illustrates how the piston  5 , which is also rotating, moves the screwed joint  4  to a new position during a crash and hence pulls the airbag cover  2  toward the airbag module  9 .  
         [0033]    For the purpose of further illustrating the invention, the gas generator housing  16  is shown in an unwound state in FIG. 5. This shows the guideways  20  and a gas passage hole  21 . A “brake”  22  is formed at the end of at least one of the guideways  20 . This “brake”  22  acts by bending and clamping the screw(s)  14  in the end position. The brake  22  is intended to prevent the airbag cover  2  from rebounding due to its impact energy (about 400 g). Other blocking, clamping and locking mechanisms are readily familiar to the person skilled in the art and can be employed accordingly. The same applies to the screws  14 , which are to be understood merely as examples of appropriate extensions that interact with a guideway in an appropriate manner.  
         [0034]    The following combinations of features are furthermore within the scope of the present invention:  
         [0035]    The airbag device preferably contains a mechanism that is driven by an explosive, which pulls the airbag cover into the airbag module. A refinement of such an embodiment is characterized in that the mechanism is configured in such a way that a cup-shaped piston sealed off with an accurate fit is placed over the generator and is at the same time guided in the housing of the module. In addition, the piston can move like a screw, i.e. helically, in guideways in the housing in such a way that cables or other connecting devices, e.g. straps, starting therefrom are moved in the transverse and longitudinal directions due to the helically embodied guideways. A cable fastening can be attached to the piston and guided in the guideway in such a way that the cable fastening and the guideway form a unit. The guideway(s) can furthermore be configured in such a way that there is a sufficient component of motion to move the airbag cover(s). The mechanism for moving the airbag cover into the module or dashboard is very simple. Such airbag devices are advantageous particularly for light airbag covers or airbag covers that are easy to open, e.g. those that are not integrated into the body of the dashboard.  
         [0036]    [0036]FIG. 6 shows an airbag generator  118 , around which annular pistons  101  and  102  are mounted in such a way that a gas outlet  106  is formed between the annular pistons  101  and  102 . Pulling cables  103  and  109  are secured on the annular pistons  101  and  102  through the use of thimbles  110  and  111 .  
         [0037]    The annular pistons  101  and  102  are encased by a cylindrical tube  115  on the outside to form a compression space  114 . The cylindrical tube  115  is provided with covers  116  and  117  at both ends to limit the movement of the annular pistons  101  and  102 . Damping devices  104  and  105  are fitted to limit the energy of the annular pistons  101  and  102 . The annular pistons  101  and  102  are sealed off with a plastic  119 , e.g. POM (polyolefin material), that melts due to pressure and/or temperature. FIG. 6 also shows how the gas stream  108  is supplied to the airbag  107  via the controlled gas supply  112 .  
         [0038]    Due to an explosion in the generator  118 , the annular pistons  101  and  102  move in such a way that the pulling cables  103  and  109  are pulled downward. End walls  120  and  121  of an airbag case or airbag-module housing  122  are provided with the shaped feature  126  in such a way that airbag flaps  123 ,  124  rest there and slide about the latter along a roof-shaped gable  125 , as shown in FIG. 7.  
         [0039]    [0039]FIG. 7 shows a side view of FIG. 6. The pulling cables  103  and  109 , the thimbles  110  and  111 , the airbag module  113 , the cylindrical tube  115 , the generator  118 , the airbag flaps  123 ,  124  and the gable  125  of the airbag module  113  can be seen here.  
         [0040]    [0040]FIG. 8 shows the same system but with deflection pulleys  127  and  128 , which, as shown in FIG. 8, are mounted between the generator  118  and the cylindrical tube. This gives a very space-saving solution. The pulling cables  103  and  109  are passed through the cover  116  and  117  in such a way that they can be gripped easily for mounting on the airbag flaps  123  and  124 . FIG. 10 shows an alternative mechanism to the two annular pistons  101  and  102  in case the resistance of the airbag flaps causes them to move different distances at different speeds and hence pull the airbag flaps  123  and  124  askew. To avoid this problem, racks  133  and  134  are mounted on the annular pistons  101  and  102  in such a way (FIG. 10) that they are pulled in a positively guided manner over a gearwheel  129  running on a spindle  130  which is secured on the gas generator. This forces the two annular pistons  101  and  102  to move in synchronism. For better sealing, small plastic gearwheels  131  and  132  run simultaneously in pockets of the annular pistons  101  and  102 , minimizing the leakage flow of gas and being embodied in such a way that they melt due to pressure and/or heat.  
         [0041]    [0041]FIG. 11 shows an individual annular piston  102 , which is used in the case of a gas outlet  106  on one side of a generator  118 . The pulling cables  103  and  109  are guided in the manner shown and, in this alternative, are guided along the outside of the airbag module  113 .  
         [0042]    Methods of making or using the airbag device according to the invention emerge in a corresponding manner from embodiments of the airbag device.  
         [0043]    In summary, an airbag device with a simple airbag-cover pull-in mechanism is provided, which is driven through the use of a piston placed over a generator and by the gas pressure of the latter. In all cases, the movement and force are sufficient for airbag covers that are easy to open (low weight, separate component).  
         [0044]    In particular, the invention provides a drive mechanism for flaps of an airbag module in a space-saving construction. This is achieved, according to one aspect, with a helical movement of a piston for winding up pulling cables. According to another aspect of the invention, this is achieved with annular pistons in case the airbag generator is of small diameter and fills the module predominantly lengthways, making it impossible to accommodate a cup-shaped piston, for example. Space-saving annular pistons are preferably used for thin and long generators. Internal guidance of the cables within the module is furthermore advantageous. A piston seal that melts is preferably used. Simple access to the pulling cables at the end is furthermore preferably provided.  
         [0045]    The above features and combinations of features of the exemplary embodiment which are illustrated in the drawings serve merely to illustrate the invention by way of example and are not meant to restrict the invention. The scope of the disclosure of the present description in its entirety is determined by what the person skilled in the art can readily gather from the claims but also from the description, the drawing and the complete contents of Published, Non-Prosecuted German Patent Application No. DE 198 44 412 A1 and International Publication No. WO 99/58389 and the above-mentioned applications which were filed for the applicant or the assignee of the present application. In particular, the invention furthermore includes all variants, combinations, modifications and substitutions which the person skilled in the art can gather from the entire disclosure of the present documents, including the earlier applications mentioned at the outset and the specialist knowledge entailed. In particular, all the individual features and configuration options of the invention and of its exemplary embodiments can be combined.