Abstract:
A gas bag module for a vehicle occupant restraint system, including a housing ( 10 ) for a gas generator and a gas bag which can be unfolded by the latter, and having a cover ( 16, 18 ) which can be converted from a closed position into an open position, the cover ( 16, 18 ) being connected to the housing ( 10 ) by means of at least one hinge ( 30 ), is characterized in that the cover ( 16, 18 ) is connected to a swivel section ( 20 ) which in turn is connected to the housing ( 10 ) by means of the hinge ( 30 ).

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a gas bag module for a vehicle occupant restraint system, comprising a housing for a gas generator and a gas bag which can be unfolded by the latter, and comprising a cover which can be converted from a closed position into an open position, the cover being connected to the housing by means of at least one hinge and the cover being connected to a swivel section which in turn is connected to the housing by means of the hinge. 
     Such a gas bag module is known from EP 0 680 852. Here, the cover is opened by the deploying gas bag after activation of the gas generator. Since the cover of such a gas bag module is connected with one of its outer rims to either the housing or a surrounding vehicle panelling, the cover will swing into the inside of the vehicle space when opening. This results in the risk for the vehicle occupant of being hit by the cover as it opens. Further, the force for opening the cover has to be made available exclusively by the deploying gas bag. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention provides a gas bag module in which the cover presents no risk for the occupant of being hit by the cover and in which the force for opening the cover is made available at least in part by an element which assists the opening action. A gas bag module of the type initially mentioned is distinguished according to the invention in that a spring is provided which biases the swivel section, with respect to the housing, into a position which corresponds to the open position of the cover. The use of a swivel section additionally enables the opening cover to swing away from an occupant, whereby any impact risk is reduced or even eliminated. 
     Advantageous developments of the invention read from the subclaims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following, the invention is described with reference to various embodiments illustrated in the attached drawings, in which 
     FIG. 1 shows a perspective view of a gas bag module according to a first embodiment of the invention with a closed cover; 
     FIG. 2 shows a side view of the gas bag module of FIG. 1; 
     FIG. 3 shows a side view of the gas bag module according to the first embodiment with the cover partly open; 
     FIG. 4 shows the gas bag module of FIG. 3 where some components have been omitted in the interest of better clarity; 
     FIG. 5 is a perspective view of the gas bag module of FIG. 3; 
     FIG. 6 shows a perspective view of a gas bag module according to a second embodiment of the invention, with the cover partly open; 
     FIG. 7 provides another perspective view of the gas bag module of FIG. 6; 
     FIG. 8 shows the gas bag module of FIG. 7 in a side view in which some components have been omitted for better clarity; 
     FIG. 9 is a perspective view of a gas bag module according to a third embodiment of the invention, where part of the cover has been omitted in the interest of better clarity; 
     FIG. 10 is a side view of the gas bag module of FIG. 9; 
     FIG. 11 is a partial perspective view of the gas bag module of FIG. 9; 
     FIGS. 12 and 13 are side views of a gas bag module according to the third embodiment of the invention, where the cover is shown open in part and fully open, respectively; 
     FIG. 14 is a perspective view of the gas bag module of FIG. 13; 
     FIG. 15 shows a partial perspective view of the gas bag module of FIG. 14; 
     FIGS. 16 to  18  show broken sectional views of different embodiments of the parting line between two cover parts. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1 to  5  illustrate a gas bag module according to a first embodiment of the invention. The gas bag module contains a housing  10  which comprises a lower part  12  to house a gas generator, and an upper part  14  to house a gas bag. The open side of the upper part  14 , intended for the emergence of the gas bag, is closed by a cover which consists of two components  16 ,  18 . Each component of the cover is connected to the housing  10  by means of a swivel section  20 . Each swivel section consists of two components  22 ,  24 , which are connected to each other by means of a hinge  26 . Each component  22  is connected to the corresponding component of the cover by means of a hinge  28 , and each component  24  is connected to the housing by means of a hinge  30 . The hinges  30  are attached to the upper part  14  of the housing  10  by means of screw bolts  32 . 
     The three hinges  26 ,  28 ,  30  extend in parallel to each other and along one of the longitudinal sides of the upper part  14  of the housing  10 . The lower hinge  30 , which connects the swivel section  22 ,  24  with the housing, extends along the longitudinal edge of the upper part  14  facing the lower part  12  of the housing. 
     From the position shown in FIGS. 1 and 2, where the two components  16 ,  18  of the cover adjoin each other along a parting line  34 , the cover can be brought into an open position. In this position, both cover parts  16 ,  18  are open. For better intelligibility, FIGS. 3 to  5  show the gas bag module with only one component of the cover being open. Here it can be seen that the corresponding component, in this particular case component  16 , is displaced towards the lower part  12  of the housing  10  when it is brought into its open position. It can be clearly seen that the hinge  28  of the opened component  16  is moved downwards during the opening process, that is away from a vehicle occupant to be restrained by the gas bag module. This displacement is due in particular to the fact that the swivel axis of the swivel section, formed by the hinge  30 , is located at a distance from a plane which is defined by the cover in the closed state. 
     FIGS. 6 to  8  illustrate a gas bag module according to a second embodiment of the invention. Unlike the first embodiment, the swivel section  20  in this arrangement has a one-piece structure. Adjoining the components  16 , 18  of the cover, an inner space panelling  40  of the vehicle is shown, in which the gas bag module is arranged. Further, a securing frame  42  for a gas bag (not illustrated) is shown schematically inside the upper part, which bag may be arranged inside the upper part  14 . 
     It can be seen that, on opening, each component of the cover disappears behind the inner space panelling  40 . This is assured by the coordinated action of both the hinges  28  and  30  as well as the swivel section  20 , which may be swivelled relative to the corresponding cover part as well as to the housing. Since the components of the cover disappear behind the inner space panelling  40 , there is no risk for the vehicle occupant of being hit by the cover. 
     FIGS. 9 to  15  show a gas bag module according to a third embodiment of the invention. In contrast to the first and second embodiments, no hinge is here provided between the swivel section and the corresponding component of the cover; the swivel section  20  is rigidly connected to the corresponding component  16 ,  18  of the cover. A leg spring  50  is furthermore provided, one leg of which is secured to the housing and the other to the swivel section  20 . This leg spring  50  biases the swivel section  20  into a position corresponding to that one with open cover; in other words, it attempts to pivot the swivel parts  20  outwards and away from the upper part  14  of the housing  10 . The coiled part of the leg spring  50  is concentric with the swivel axis of the hinge  30 . 
     When in their closed position, both the opposing outer edges of the two components  16 ,  18  of the cover make contact with their facing edges of the inner space panelling  40 . In this way, a supporting force is provided which acts against the force exerted by the leg spring  50 . In addition, the facing edges of the components  16 ,  18  of the cover may be embodied in a way as illustrated in FIGS. 16 to  18 . 
     As illustrated in FIG. 16, component  16  is provided with a lip  60  which engages into a corresponding recess  62  of the component  18 . The component  18  is provided with a latching protrusion  64  which engages with the shoulder of the lip  60  of component  16 . In this way a latching connection is formed which is capable of transmitting traction forces, tending to separate the two components  16 ,  18 , up to a predetermined limit. The traction forces which may be transmitted also act to oppose the pressure provided by the leg springs  50 . 
     FIG. 17 shows that the component  16  is provided with a symmetrical lip  66  which has a protrusion  68  on both sides. The lip  66  mates with a complementary recess in the component  18 . This makes it possible to transmit traction forces up to a predetermined limit. 
     FIG. 18 shows that the component  18  is provided with a web  70  which extends in parallel to the swivel axis determined by the hinge  30 , and is generally at a right angle to a plane defined by the component  18 . The web  70  engages in a complementary groove  72  in the component  16 . This embodiment is also capable of transmitting traction forces between the two components  16 ,  18 . 
     When the gas bag located inside the upper part  14  is activated, it provides a thrust action on the two components  16 ,  18  of the cover. These are then swivelled to a slight degree so that their outer rims, in contact with the inner space panelling  40 , are pushed under the inner space panelling. At the same time, there is exerted such a force on the components  16 ,  18  that the traction force transmittable by the latching connection between the two components is exceeded. The two cover parts  16 ,  18  are then shifted outwards under the inner space panelling  40 , assisted by the leg spring  50 . Due to the pre-determined swivel path, there occurs no risk for a vehicle occupant of being hit by the cover.