Abstract:
The invention relates to an airbag assembly comprising a mechanism for a stationary driver&#39;s airbag, i.e. an airbag that does not rotate with the rotation of the steering wheel. Said airbag assembly is configured in such a way that the mechanism is situated inside the steering column. The invention also relates to a gear and an operating method for an airbag assembly of this type.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention pertains to an airbag assembly, a gear and all operating method for said assembly. The invention specifically pertains to a non-rotating driver&#39;s airbag in a steering wheel of an automobile. 
       BACKGROUND OF THE INVENTION 
       [0002]    Nowadays, driver&#39;s airbags in practice rotate with the steering wheel. This has two disadvantages. First, the airbag needs to be “round” because the position of the steering wheel during an accident is unpredictable. In addition, the power supply of the actual airbag device usually needs to be realized with an expensive so-called “volute spring.” The latter also applies to the connection of switches for “multifunctional steering wheels” customarily installed in modern automobiles. This topic is already the object of additional developments, for example, as described in publications by the firms Autoliv, TRW, Faurecia, ZF and Takata, among others. 
         [0003]    A non-rotating airbag is already disclosed in Offenlegungsschrift DE 21 31 902 of Jun. 26, 1971. In this case, the “sun gear” of a “planet gear” mounted in the steering wheel is fixed in the upper end of the steering gear shaft. Alternatively, the power is transmitted between the gearwheel on the end of the steering gear shaft and the “sun gear” in the steering wheel by means of three “planet gears.” The disadvantage of such constructions is the weight of the gear in the steering wheel that is particularly unsuitable for automobiles with diesel engines due to disagreeable vibrations. Other disadvantages can be seen in that the steering gear shaft rotates with a speed that is two-times to three-times faster and in that the rotating direction of the steering gear shaft is reversed. Completely new steering gears on the front axle and different leverages are required in this case. 
         [0004]    In addition, DE 21 31 902 discloses the state of the art for “stationary” cable leadthroughs for the operation of switches. In this case, the steering shaft is divided as well as offset and connected by means of gearwheels. 
         [0005]    Furthermore, German patent 872011 of Jul. 8, 1949 discloses a non-rotating clock in a steering wheel that is realized by means of planet gears. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention is based on the objective of improving the existing technology and has attained this objective. 
         [0007]    In the context of the present invention, the steering column is essentially divided, in particular, into an upper and a lower half. A zone suitable for the stationary connection of a “non-rotating” airbag including its cable leadthrough is preferably situated in the region between the steering column halves. 
         [0008]    The upper part and the lower part of the steering wheel shaft are connected with various types of gears in alternative embodiments. The gear is preferably situated in the region of the connection of the steering column and therefore does not lead to an increased vibration tendency of the steering mechanism. 
         [0009]    In other alternative embodiments, the steering wheel has the same rotating direction and rotational speed as the “lower” steering shaft. New steering gears are not required in this case. 
         [0010]    Consequently, the invention discloses an alternative gear, particularly with respect to the state of the art, for stationary positioning of a driver&#39;s airbag in an automobile independently of the steering angle of the steering wheel. This makes it possible to utilize airbags with a superior and encompassing shape that also cover the A-column. The cable lead-throughs of the airbag and the multifunctional steering wheel can be simply realized in a stationary fashion. 
         [0011]    Solutions optimized with respect to costs, structural space and functions are illustrated in the figures in the form of corresponding embodiments and described below. In this respect, individual characteristics and combinations of characteristics may also be combined within the scope of professional expertise, and the respective combinations of characteristics defining individual embodiments do not restrict the invention to such combinations only. 
         [0012]    The incorporation of a servo mechanism and, if so required, a dynamic change in the angle of rotation between the steering wheel and the steering shaft can be realized. 
         [0013]    Special design options and advantages of the present invention and its embodiments are:
       improved protective effect of the airbag due to its specific shape.   simple cable lead-throughs for the airbag and the multifunctional steering wheel.   solid connection of the airbag support tube on/to a stationary element in/on the steering column tube.   alternatives with identical or opposite rotating directions of steering wheel and steering shaft.   alternatives with identical or different rotational speeds of steering wheel and steering shaft.   space-saving construction, usually within the steering column tube.   alternative mechanisms with cylindrical gearwheels, angular gearwheels or a chain (see, e.g.,  FIG. 16 ).   a “highlight” in the form of a parallel planet gear set within the steering column tube, namely without influencing the rotating direction or the rotating speed (see, e.g.,  FIG. 6 ).   only one planet gear set required in the stationary housing of the steering column tube if the steering gear is adapted accordingly (see, e.g.,  FIG. 7 ).   alternatives with a bevel gear for identical rotational speed of steering wheel and shaft, alternatively with opposite or identical rotating direction (see, e.g.,  FIGS. 10 and 11 ).   simple incorporation of a servo mechanism, namely either constant or dynamically dependent on the angle of rotation and the speed (see, e.g.,  FIGS. 13 and 14 ).   another “highlight” in the form of a gear and an airbag with static cable leadthrough rigidly connected to the steering column tube. The steering wheel with integrated sun gear drives planet gears on a shaft. The drive is realized in the form of a planet gear that meshes with a sun gear forming the end piece of the steering shaft. This is realized within the flange of the steering wheel or within the stationary steering column tube, respectively (see, e.g.,  FIGS. 18 and 19 ).       
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    The invention is merely elucidated in an exemplary fashion with reference to the embodiments and application examples in accordance with the present invention, that are illustrated in the figures and described below, in which: 
           [0027]      FIGS. 1   a ,  1   b , and  1   c  show an embodiment with a steering wheel; 
           [0028]      FIGS. 2   a ,  2   b , and  2   c  show section A of  FIGS. 1   a ,  1   b  and  1   c;    
           [0029]      FIGS. 3   a ,  3   b , and  3   c  show an intermediate gear; 
           [0030]      FIGS. 4   a ,  4   b  and  4   c  show a differently designed steering gear; 
           [0031]      FIGS. 5   a ,  5   b  and  5   c  show an alternate form of a differently designed steering gear; 
           [0032]      FIGS. 6   a ,  6   b , and  6   c  show another embodiment, in which the airbag rests on a molded tube; 
           [0033]      FIGS. 7   a ,  7   b , and  7   c , show another embodiment, in which the lower sun gear and the lower planet gear are eliminated; 
           [0034]      FIGS. 8   a ,  8   b , and  8   c  show the arrangement of the sun gears and the planet gears; 
           [0035]      FIGS. 9   a ,  9   b , and  9   c  show section C of  FIGS. 6   a ,  6   b , and  6   c;    
           [0036]      FIGS. 10   a ,  10   b , and  10   c  show an alternative to the technology that is illustrated in  FIGS. 7   a ,  7   b , and  7   c;    
           [0037]      FIGS. 11   a ,  11   b , and  11   c , show a gearwheel and axle added to the embodiment according to  FIGS. 10   a ,  10   b , and  10   c;    
           [0038]      FIGS. 12   a ,  12   b , and  12   c  show another embodiment in the form of an alternative with a laterally attached transmission; 
           [0039]      FIGS. 13   a ,  1   t   3   b , and  13   c , show a variation of  FIGS. 12   a ,  12   b , and  12   c , including a servo mechanism/power steering system; 
           [0040]      FIGS. 14   a ,  14   b , and  14   c , show a device for changing the transmission; 
           [0041]      FIGS. 15   a ,  15   b , and  15   c  show means for horn actuation; 
           [0042]      FIGS. 16   a, b, c  show an alternative in which the mechanism is divided into a short steering column shaft and a long steering column shaft; 
           [0043]      FIGS. 17   a, b, c  show section D of  FIGS. 16   a ,  16   b  and  16   c;    
           [0044]      FIGS. 18   a ,  18   b , and  18   c  show another embodiment in which all outer stationary steering column tube carries the stationary airbag; 
           [0045]      FIGS. 19   a ,  19   b , and  19   c  show section E of  FIGS. 18   a ,  18   b  and  18   c;    
           [0046]      FIGS. 20   a ,  20   b , and  20   c  show an alternative embodiment according to  FIGS. 19   a ,  19   b , and  19   c , in which four sets of gearwheels are used. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0047]    Preferred and/or advantageous embodiments of the invention result from the claims and their combinations as well as the entire present application documents. 
         [0048]    Embodiments of the invention are described in greater detail below with reference to the figures. 
         [0049]    The invention is merely elucidated in an exemplary fashion with reference to the embodiments and application examples that are illustrated in the figures and described below. Process and device characteristics also respectively result analogously from device and process descriptions. 
         [0050]    In the individual figures and illustrations, identical or similar components or components with identical or similar functions are identified by the same reference symbols. The illustrations in the figures also reveal characteristics that are not provided with reference symbols, namely irrespective of the fact whether or not such characteristics are described below. On the other hand, characteristics that are mentioned in the present description but that are not visible or illustrated in the figures are self-explanatory for a person skilled in the art. 
         [0051]    Individual characteristics that are cited and/or illustrated in connection with specific embodiments are not restricted to these embodiments or the combination with the remaining characteristics of these embodiments, but may also be combined with any other variations within the bounds of technical possibility, namely even if they are not discussed separately in the present documents. 
         [0052]      FIGS. 1   a, b, c  show a first embodiment with a steering wheel  1  that is not conventionally mounted on the steering column shaft  2  by means of a cone  3  and a nut  4 , but rather on a second hollow shaft  5  arranged laterally parallel thereto. Analogous to the actual steering column shaft  2 , this hollow shaft  5  is also supported in a steering column housing  6 .  FIGS. 1   a, b, c  show the two bearings  7  and  8  of the hollow shaft and the upper bearing  9  of the actual steering column shaft  2 . 
         [0053]    Both shafts, namely the steering column shaft  2  and the hollow shaft  5 , are provided with gear rims  10  and  11  that precisely “mesh” without play. If the transmission is 1:1, the steering column shaft  2  rotates exactly as fast as the hollow shaft  5 . This represents the normal case. Other transmissions can be realized. 
         [0054]    The embodiment according to  FIGS. 1   a, b, c  does not show the option of changing the transmission in accordance with today&#39;s conventional technical standard. This requires engaging and disengaging meshing gears on each of the shafts  2  and  5 . During parking maneuvers at slow speeds, this would result in indirect steering, i.e., in a smoothly operating steering mechanism. At higher speeds, this would result in a direct and more stable transmission. Other shifting stages can be realized. However, this is not discussed in greater detail because variable speed transmissions with shafts form part of the state of the art and can be correspondingly integrated into the invention or combined therewith by any person skilled in the art. The shifting pulse then preferably results from the scanned speed of the vehicle. 
         [0055]    A continuous variation of the transmission can also be achieved with an automatic transmission that may be realized in accordance with any customary technical design. 
         [0056]    After the steering wheel  1  is installed on the hollow shaft  5 , an airbag  12  provided with another hollow shaft  13  is inserted into the hollow shaft  5 . A secure and stationarily positioned mounting is provided on the end of the hollow shaft  13  of the airbag  12 . In the embodiment shown, this consists of a cone  14  with not-shown slot-and-key positioning. This configuration is secured by drawing the cone  14  or the hollow shaft  13  into a cone  15  of the steering housing  6  by means of a nut  16 . Other customary technical mounting options may be considered and fall under the scope of the present invention. 
         [0057]    The airbag  12  is now stationarily mounted on its hollow shaft  13  in the steering column housing  6 . The hollow shaft  5  rotates about this hollow shaft  13  on the bearings  7  and  8 . The steering wheel  1  is mounted on this hollow shaft  5 . If so required, slide bushings  17  and  18  may be alternately installed in order to avoid friction between the two hollow shafts  5  and  13 . 
         [0058]    Another advantage of this “stationary” airbag  12  can be seen in that all cables  19  can extend through its hollow shaft  13 . This applies analogously and particularly to the cables of a (not-shown) multifunctional steering wheel. In this case, its switches are non-rotatably or similarly mounted on the (not-shown) airbag housing. 
         [0059]    In the embodiment shown in  FIGS. 1   a, b, c , the steering wheel  1  turns in the opposite direction of the steering column shaft  2  (see also  FIGS. 2   a, b, c ). This means that, for example, a lower pinion gear  21  needs to “mesh” with the opposite side of a rack  22  in the steering gear housing (see also  FIGS. 5   a, b, c ) or the steering arms need to extend rearward in a mirror-inverted fashion if they extend forward prior thereto and vice versa (see also  FIGS. 4   a, b, c ). 
         [0060]    If an existing steering gear and an existing steering mechanism should be used, an intermediate gear  20  is preferably arranged between the gear rim  10  of the hollow shaft  5  and a gear rim  11  of the steering column shaft  2  (see also  FIGS. 3   a, b, c ). 
         [0061]      FIGS. 6   a, b, c  show another embodiment, in which the airbag  12  rests on a molded tube  23  that also serves for leading through the cables  19 . The cables  19  of (not-shown) “multifunctional steering wheels” also extend through this tube. The tube  23  is supported in an upper steering column shaft  26  by means of a bearing  28 . The molded tube  23  rests on a molded bearing part  24  that is fixed in the steering column housing  6  with screws  25  or the like. The upper ( 26 ) and the lower steering column shaft  27  are respectively supported separately in the steering column housing  6  underneath and above the molded bearing part  24 . “Sun gears”  29  and  30  are mounted in the upper ( 26 ) and the lower steering column shaft  27 , namely on their respective ends. An axle  31  is inserted into and supported in the molded bearing part  24 . The ends of the axle  31  are provided with planet gears  32 ,  33 . The planet gears  32 ,  33  mesh with the sun gears  29 ,  30  and transmit the rotational movement of the upper steering column shaft to the lower steering column shaft  27 . The advantage of this assembly is the possible 1:1 rotary motion between the bottom shaft section and the top shaft section and the preservation of the rotating direction. In addition, this embodiment represents a very compact gear that can be arranged within the steering column housing without requiring additional space. 
         [0062]    In another embodiment that is shown in  FIGS. 7   a, b, c , the lower sun gear  30  and the lower planet gear  33  are eliminated. The axle  31  of the upper planet gear  32  is rigidly connected to the lower steering column shaft  27 . It is eccentrically supported in the molded bearing part  24 . In this case, the advantage can be seen in the eliminated gears  30 ,  33 ; the disadvantages are the reversed rotating direction of the lower steering column shaft  27  relative to the upper steering column shaft  26  and a forced speed increasing transmission of approximately 1:2. A differently designed steering gear is required on the front axle (see, e.g.,  FIGS. 4   a, b, c  and  5   a, b, c , wherein the number of teeth of the lower pinion gear  21  would have to be reduced in  FIGS. 5   a, b, c  in accordance with the transmission). 
         [0063]      FIGS. 8   a, b, c  show the arrangement of the sun gears  29 ,  30  and the planet gears  32 ,  33  in the form of section B of  FIGS. 6   a, b, c  and  7   a, b, c . The molded tube  23  lies in the free region between the gears. 
         [0064]      FIGS. 9   a, b, c  show section C of  FIGS. 6   a, b, c . Screws  25  are used for fixing the molded bearing part  24  and the molded tube  23 . This figure also shows the plug connector  34  for the cables  19  that is held by the assembly of the molded tube  23  and the molded bearing part  24 . 
         [0065]      FIGS. 10   a, b, c  show an alternative to the technology that is illustrated in  FIGS. 7   a, b, c  and described with reference thereto, namely in the form of an additional embodiment with helical gearwheels  35 ,  36 ,  37 . The molded bearing part  24  is replaced with a welded sheet metal construction  38 . The advantage of this assembly is that the upper and the lower steering column shafts  26 ,  27  can have the same rotational speed. However, the shafts rotate in opposite directions. 
         [0066]    In another embodiment that is illustrated in  FIGS. 11   a, b, c , another gearwheel  39  and its axle  42  are added to the embodiment according to  FIGS. 10   a, b, c  in order to realize the same rotating direction of both steering column shafts  26 ,  27 . An appropriate stamped sheet metal housing  41  is provided for the support  40 . 
         [0067]      FIGS. 12   a, b, c  show another embodiment in the form of an alternative with a laterally attached transmission  43 . Two gearwheels  44 ,  45  mounted on the upper and the lower steering column shaft  26 ,  27  “mesh” with both gearwheels  46 ,  47  on the gear axle. All components are installed in a housing  49  as shown in the figures. This represents a simple solution if sufficient space is available. 
         [0068]    In another embodiment shown in  FIGS. 13   a, b, c , the variation illustrated in  FIGS. 12   a, b, c  is used for flanging on a servo mechanism/power steering system  50  in the simplest possible fashion because the free shaft end  51  of the gear is more cost-efficient than today&#39;s conventional “docking” of the power steering system. 
         [0069]    In another embodiment that is shown in  FIGS. 14   a, b, c , the gear  52  is separated and a device  53  for changing the transmission is arranged in between. A computer  54  records the speed  55  of the automobile and the angle of rotation  56  of the steering wheel and calculates the transmission ratio  57  between the lower and the upper steering column shafts  26 ,  27  therefrom. The technical design of the device  53  for changing the transmission and its peripheral equipment are not discussed in greater detail because this is already standard equipment, e.g., since 2003 in the so-called 5-series of BMW automobiles. A servo mechanism and a device for changing the transmission may also be combined. The relevant aspect of the invention is the connection of both known steering improvement mechanisms at this location because the steering column shaft is divided anyway in this region due to the “stationary” airbag  12 . 
         [0070]    Since the airbag  12  is seated on a tube  23 , it is advantageous to arrange the horn actuation  59  in a correspondingly molded tube  58  with the aid of an inserted tube  60  that is telescopically moved against a spring  61  and thusly closes the contacts  62 . The telescopic travel can be very easily restricted with conventional technical means as illustrated in the figures. This central unit is exceptionally cost-efficient and above all compact (see also  FIGS. 15   a, b, c ). 
         [0071]      FIGS. 16   a, b, c  show an alternative in the form of yet another embodiment. The mechanism is divided into a short steering column shaft  63  and a long steering column shaft  64 . The steering column shafts  63  and  64  are supported in the first housing (1)  69  and the second housing (2)  73 . The steering column shafts  63  and  64  are provided with first and second chain wheels (1) and (2)  66  and  67 . These chain wheels are connected to the chain  71 . The chain  71  needs to be tensioned such that it has “no play;” in the embodiment shown, this is realized in an exemplary fashion with two setscrews  68 . The setscrews connect the two housings  69  and  73 , have left-hand and right-hand threads and make it possible to render the chain  71  “free of play” by turning the screws. Other chain tensioning devices can also be utilized. All cables  19  can extend through the continuously open “short” steering column shaft  63 . The stationary tube  72  is mounted on a cover  65  that forms part of the first housing (1)  69 . 
         [0072]      FIGS. 17   a, b, c  show the arrangement of the short steering column shaft  63 , the long steering column shaft  64 , the first chain wheel (1)  66 , the second chain wheel (2)  67 , the setscrews  68 , the first housing (1)  69 , the sheet metal enclosure  70 , the chain  71 , the stationary tube  72 , the airbag  12  and the second housing (2)  73  in the form of sections D of  FIGS. 16   a, b, c.    
         [0073]      FIGS. 18   a, b, c  show another particularly simple alternative in the form of yet another embodiment. An outer stationary steering column tube  74  carries the stationary airbag  12  on its upper end. A special steering wheel  1  with a gearing  75  is supported on the end of the stationary steering column tube  74 . When the steering wheel  1  is turned, the gearing  75  drives a gearwheel  76  that turns perpendicular to the gearing  75  of the steering wheel  1 . The gearwheel  76  embodiments and their illustrations in the figures, and is able to combine these variations, modifications, substitutions and combinations with that person&#39;s professional expertise and the state of the art. It is possible, in particular, to combine all individual characteristics and possible designs of the invention as well as the embodiments thereof.