Patent Publication Number: US-6702322-B2

Title: Vehicle occupant restraint device

Description:
RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 09/665,699, filed Sep. 20, 2000, and corresponds to German Application Nos. 299 16 526.4, filed Sep. 20, 1999 and 100 20 353.1, filed Apr. 26, 2000, and assigned to the assignee of the present application. 
    
    
     TECHNICAL FIELD 
     This invention relates to a restraint device for an occupant in a vehicle having a steering wheel, a dashboard with a lower end limiting a footwell, an A-pillar and a windshield. 
     BACKGROUND OF THE INVENTION 
     In certain accident situations, known vehicle occupant restraint devices comprising a gas bag for protecting the thorax area of a vehicle occupant often provide only an insufficient protection against injuries of the cervical spine. 
     BRIEF SUMMARY OF THE INVENTION 
     By means of the invention a vehicle occupant restraint device is provided, which can flexibly adapt to the respective accident situation, and by means of which the risk of injury of a vehicle occupant can be kept extremely small. The restraint device according to the invention for an occupant in a vehicle having a steering wheel, a dashboard with a lower end limiting a footwell, an A-pillar and a windshield, comprises a first gas bag for protecting the thorax area of a vehicle occupant, and a second gas bag for supporting the first gas bag. The second gas bag has a deployed condition and extends at least partly over the windshield of the vehicle in the deployed condition. 
     If required in the case of a vehicle collision, the additional second gas bag serves as a support for the first gas bag and maintains the same in a predetermined position during the course of the accident, so that an optimum protective function of the first gas bag is ensured. The ensured defined position of the first gas bag and the perhaps possible division of the impact energy of the vehicle occupant over two separate gas bags allows to reduce the volume of the first gas bag from about 100 to 150 liters of commonly used thorax gas bags to about 70 to 90 liters without impairing the protective effect. Due to the reduction of the required gas quantity, less expensive gas generators can thus be used for inflating the gas bag. In addition, the use of a gas bag of reduced volume provides for a reduction of the inflation time as compared to conventional thorax gas bags, and the occupant has a reduced risk of injury during the process of deployment. 
     The second gas bag in addition prevents a contact of the head of the occupant with the windshield, where the arrangement of the two gas bags creates a specific freedom of movement for the head of the vehicle occupant, so that the acceleration moments acting on the neck are minimized during an accident. This provides for a significant reduction of the load acting on the cervical spine. 
     Preferably, the second gas bag is arranged such that in the deployed condition it is supported on the windshield. This ensures an optimum protective effect for the vehicle occupant, as with such a constellation the first gas bag is indirectly supported on the windshield via the second gas bag, and thus the impact of the vehicle occupant can optimally be absorbed. To furthermore avoid head injuries due to a possible contact of the head of the vehicle occupant with the A-pillar of the vehicle in the case of an inclined or offset impact, the second gas bag preferably extends over at least a portion of the A-pillar in the deployed condition. 
     From a functional and constructional point of view it has turned out particularly advantageous to accommodate the second gas bag in the roof liner of the vehicle. In this preferred embodiment, the second gas bag is deployed from the top to the bottom along the windshield, which involves no hazard potential for the occupant during the deployment of the gas bag, especially when the occupant is out of position, so to speak, has no normal seating position. This is often the case with children on the front seats. In particular in the case of convertible cars, which do not have a solid roof, the second gas bag can, however, also be accommodated in the dashboard or in the region of the A-pillar of the vehicle. 
     In the case of vehicles having both a driver-side and a passenger-side restraint means with one gas bag each for protecting the thorax area, the second gas bag advantageously extends substantially over the entire width of the windshield. In the case of a collision it can then serve as a support both for the driver-side and for the passenger-side thorax gas bag. However, there may also be provided two separate systems with one inventive vehicle occupant restraint device each. 
     In a further embodiment of the inventive device a traction system is provided, which after a vehicle collision pulls the deployed second gas bag away from the windshield, in order to again clear the field of vision for the driver and/or the passenger. 
     The first gas bag for protecting the thorax area of the vehicle occupant may be accommodated in the steering wheel in the case of a device for the driver of a motor vehicle, or in the dashboard of the vehicle in the case of a device for the passenger. An additional protective function is obtained in the latter case by accommodating the first gas bag in the lower portion of the dashboard limiting the footwell. The gas bag extending from the footwell over the dashboard in the deployed condition then also performs the function of a knee protection device. 
     An additional protection of the knee area of the vehicle occupant can also be achieved in that a third gas bag is provided, which is deployed in the footwell of the vehicle. A particularly space-saving embodiment is one where a gas generator is provided for inflating more than one of the gas bags. 
     An even better adaptation to the respective accident situation and also to the parameters of the vehicle occupant is obtained in that a multi-stage gas generator is used for inflating at least the first gas bag. Depending on the intensity of the vehicle collision and the weight of the vehicle occupant, the first gas bag can for instance be inflated harder or less hard. This also provides for a controlled time delay during inflation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows an embodiment of a driver-side vehicle occupant restraint device in a motor vehicle; 
     FIG. 2 shows an embodiment of a passenger-side vehicle occupant restraint device in a motor vehicle; 
     FIG. 3 shows a variant of the embodiment of FIG. 2; 
     FIG. 4 shows a further embodiment of a passenger-side vehicle occupant restraint device in a motor vehicle; 
     FIG. 5 shows embodiments of the part of a driver-side and a passenger-side vehicle occupant restraint device having the second gas bag with separate gas supply systems in a motor vehicle in a-top view; 
     FIG. 6 shows embodiments of the part of a driver-side and a passenger-side vehicle occupant restraint device having the second gas bag with a common gas supply system in a motor vehicle in a top view; 
     FIG. 7 shows a part of the driver-side vehicle occupant restraint device of FIG. 4 in an enlarged view; 
     FIG. 8 shows a section through the part of the vehicle occupant restraint device along line VII—VII of FIG. 7 in the non-inflated condition of the second gas bag; and 
     FIG. 9 shows the vehicle occupant restraint device of FIG. 8 in the inflated condition. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 represents a vehicle occupant restraint device for the driver of a motor vehicle in the activated condition. A first gas bag  12  for protecting the thorax area of the vehicle occupant  10  has deployed out of the steering wheel  14 . A second gas bag  16 , which has deployed from the top to the bottom before the first gas bag  12  from a fixture  18  in the roof liner  20  above the windshield  22 , extends over the upper portion of the windshield  22  of the vehicle. The second gas bag  16 , which directly rests against the windshield  22 , indirectly supports the first gas bag  12  at the windshield  22 , so that the same is held in its predetermined position. Furthermore, the second gas bag  16  preferably covers almost the entire A-pillar  23  of the vehicle towards the occupant. At the outer surface of the second gas bag  16  a first end  24  of a strap  25  is fixed. The second end  26  of the strap is coupled to the piston  30  of a piston/cylinder unit  28  disposed in the roof liner  20  of the vehicle. By activating this piston/cylinder unit  28  after the vehicle collision, for instance by applying a compressed gas onto the side of the piston  30  facing the windshield, the piston  30  moves away from the windshield  22  and thereby pulls the deployed second gas bag  16  away from the windshield  22 , so that the forward visibility through the windshield  22  is clear again. Strap  25  and piston/cylinder unit  28  constitute a traction system. 
     FIG. 2 shows a restraint device for the passenger of a motor vehicle, which largely corresponds to the device represented in FIG. 1, but without restraint system  24 ,  28  for the second gas bag  16 . In contrast to the device shown in FIG. 1, the first gas bag  12  for protecting the thorax area has deployed from a fixture  32  of the dashboard  33  facing the chest of the vehicle occupant  10 . In the fixture  32  of the dashboard  33  there is also indicated a multi-stage gas generator  34 , by means of which the first gas bag  12  is inflated corresponding to the respective requirements. The second gas bag  16  however, can also be arranged under the cladding of the A-pillar  23 . 
     The vehicle occupant restraint device represented in FIG. 3 differs from the one shown in FIG. 2 in that the first gas bag  12  was accommodated in a fixture  36  disposed in the lower portion  37  of the dashboard  33  limiting the footwell  35  and has deployed from the footwell over the dashboard  33  up to the second gas bag  16 , which in turn supports the first gas bag  12  at the windshield  22 . In this embodiment, the first gas bag  12  in addition performs the function of a knee protection means, which otherwise requires for instance the provision of a separate, so-called kneebag. 
     In the embodiment of FIG. 4 a third gas bag  17  for protecting the knee area of the vehicle occupant is provided in addition to the first passenger-side gas bag  12  and the second gas bag  16  on which the first gas bag  12  is supported. The third gas bag is deployed in the footwell  35  of the vehicle and is supported on a portion  37  of the dashboard  33  limiting the footwell  35 . In accordance with the represented embodiment, the second gas bag  16  has deployed from the bottom to the top out of an opening of the dashboard  33  facing the windshield  22  (preferably out of the openings of the air distribution duct), in contrast to the embodiments described so far. In this embodiment, the gas bag  16  is arranged in a region of the dashboard close to the windshield  22 . In the illustrated embodiment, all three gas bags  12 ,  16 ,  17  are inflated by a single gas generator  34  of a gas bag module which is accommodated in a fixture  32  of the dashboard  33 . There may, however, also be provided two or three different gas generators. 
     FIG. 5 represents an embodiment of the invention which provides a separate second gas bag each on the driver side and on the passenger side. In a top view of the vehicle the driver-side second gas bag  16   a  and the passenger-side second gas bag  16   b  are shown in the inflated condition. In this embodiment there is also provided a separate gas supply system including gas generators  38   a ,  38   b  and gas tubes  40   a ,  40   b  for each of the driver-side and the passenger-side second gas bags  16   a ,  16   b , which gas generators and gas tubes are accommodated in the roof liner of the vehicle. As in the embodiment shown in FIG. 6, the driver-side and the passenger-side gas bags may be supplied from a common gas supply system including a single gas generator  38  and a gas tube  40 , which extends in or through both gas bags. 
     The passenger-side gas bag module of the embodiment having the separate gas supply systems in accordance with FIG. 5 is represented in FIG. 7 in an enlarged view. The gas generator  38   a  is fixed at the vehicle roof by means of the housing  42   a . The gas tube  40   a  extends from the gas generator  38   a  through the gas bag housing  44   a  and the gas bag folded up therein, which can be better seen in the section shown in FIG.  8 . At its other end, the gas tube is fixed at the vehicle by means of a holder  46 . The portion of the gas tube  40   a  disposed in the interior of the gas bag has escape openings  48 . 
     FIG. 8 illustrates that the gas bag housing  44   a  is mounted at a reinforcing sheet of metal  50  of the vehicle roof  52  below the roof liner  20 . Upon activation (FIG.  9 ), the gas bag housing  44   a  is pressed open by the deploying gas bag. In addition, the gas bag  16  forces the roof liner  20  out of its holder  56  at the windshield  22 , so that the gas bag  16   a  can spread in the direction of the windshield  22 . 
     In all embodiments it is provided that the second gas bag  16 ,  16   a ,  16   b  is only deployed when this is required by the accident situation or by corresponding other circumstances, e.g. the parameters of the vehicle occupant  10 . 
     When using the inventive vehicle occupant restraint device including a two-stage gas generator  34  in cooperation with belt usage, seat occupation and speed sensors a number of matching combinations is possible which is increased by the factor of 2.