Patent Publication Number: US-2007120346-A1

Title: Air bag module

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to an air bag module, and more particularly, to an air bag module which suppresses the initial deployment of a cushion by a force of gradually tearing tear lines of flaps by an expansion pressure of the cushion when an expanding gas is supplied to the cushion.  
      2. Description of the Background Art  
      Generally, an air bag module is a device which is installed on a vehicle for protecting a passenger in the vehicle when a collision occurs. Such an air bag module installed on a vehicle is classified into a number of types, including a driver air bag (DAB) mounted on a handle for protecting a driver in a driver&#39;s seat, a passenger air bag (PAB) installed on an instrument panel in front of a passenger&#39;s seat for protecting the passenger in the passenger&#39;s seat, a side air bag (SAB) installed in a seat, etc. according to the installation position.  
       FIG. 1  is a cross sectional view of a passenger air bag module among air bag modules of several types. The air bag module according to the conventional art as illustrated in  FIG. 1  comprises: an air bag housing  2  fixed to a vehicle; an inflator  4  installed within the air bag housing  2  for generating a high pressure expanding gas when a collision occurs; a cushion  6  into which the expanding gas generated from the inflator  4  is injected; and a cushion retainer  10  for securing the cushion  6  to the air bag housing  2 .  
      In order to improve out-of-position (OOP) capability, one of the main capabilities of the air bag module, the air bag module further comprises first and second flaps  8  and  9  capable of preventing a sudden impact, such as a punch-out force, by which an occupant is injured as part of the cushion  6  where the expanding gas of the inflator  4  is concentrated is aggressively expanded toward the occupant during the initial deployment of the cushion.  
      That is, the first and second flaps  8  and  9  are installed so that they enclose the cushion  6  and cause friction against each other, in order to uniformly fill the expanding gas in the cushion  6  by suppressing the initial deployment of the cushion  6  by a friction force between the first and second flaps  8  and  9 .  
      Typically, the first and second flaps  8  and  9  are coated so as to have a sufficient friction force, and have such a structure in which they overlap each other in layers.  
      The operation of the thus-constructed air bag module according to the conventional art will be described below.  
      When the cushion  6  receives an expanding gas from the inflator  4 , the cushion  6  inflates as the expanding gas fills the cushion  6 .  
      At this time, since the cushion  6  is enclosed by the first and second flaps  8  and  9  at the time of initial deployment of the cushion  6 , the expanding gas is uniformly filled in the cushion  6  while suppressing the initial deployment of the cushion by a friction force between the first and second flaps  8  and  9 . At this point, as the expanding gas fills the cushion  6 , the first and second flaps  8  and  9  are gradually released by a friction against each other.  
      After the expanding gas is filled in the cushion  6  to a certain extent, and the first and second flaps  8  and  9  are completely released, the cushion  6  is expanded toward an occupant to its full shape, thereby protecting the occupant.  
      However, in the above air bag module according to the conventional art, because the initial deployment of the cushion  6  is suppressed by using a friction force caused by a frictional contact between the first and second flaps  8  and  9 , the friction force between the first and second flaps  8  and  9  varies depending on the folding method, condition and degree of coating of the first and second flaps  8  and  9 . This makes it difficult to tune a friction force of the first and second flaps  8  and  9  and test the performance therefore, and it is difficult to prevent a punch-out force phenomenon entirely.  
     SUMMARY OF THE INVENTION  
      The present invention is directed to solve the prior art problems, and has for its object to provide an air bag module which is improved in OOP capability by suppressing the initial deployment of a cushion by a force of gradually tearing tear lines of flaps by an expansion pressure of the cushion when an expanding gas is supplied to the cushion.  
      To accomplish the above object, there is provided an air bag module according to the present invention, comprising: a first flap covering one side of a cushion; and a second flap covering the other side of the cushion and having a cut-out portion that can be torn gradually by an expansion pressure of the cushion and is coupled to the first flap.  
      To accomplish the above object, there is provided an air bag module according to the present invention, comprising: an air bag housing installed on an instrument panel opposite to a passenger&#39;s seat; an inflator installed on the air bag housing for supplying an expansion pressure; a cushion accommodated in the air bag housing and capable of deploying toward the passenger&#39;s seat upon receiving the expansion pressure; a cushion retainer for coupling the cushion to the air bag housing; a first flap whose one end couples to the air bag housing to cover one side of the cushion; and a second flap whose one end couples to the air bag housing to cover the other side of the cushion, wherein the second flap has a cut-out portion coupled to the first flap and formed by being segmented by a cutting line and two tear lines that can be torn gradually by the expansion pressure of the cushion, the two tear lines being connected to the cutting line. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      In the drawings:  
       FIG. 1  is a cross sectional view of an air bag module according to the conventional art.  
       FIG. 2  is a cross sectional view of an air bag module according to the present invention;  
       FIG. 3  is a view showing an initial deployment state of the air bag module according to the present invention;  
       FIG. 4  is a view showing the condition after completion of deployment of the air bag module according to the present invention;  
       FIG. 5  is a plan view showing an exploded condition of a flap unit of the air bag module according to the present invention;  
       FIG. 6  is a deployment view showing an assembled condition of the flap unit of the air bag module according to the present invention;  
       FIG. 7  is a deployment view of the condition during initial deployment of the flap unit of the air bag module; and  
       FIG. 8  is a deployment view showing the condition after completion of deployment of the air bag module according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Hereinafter, preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.  
       FIG. 2  is a cross sectional view of an air bag module according to the present invention.  FIG. 3  is a view showing an initial deployment state of the air bag module according to the present invention.  FIG. 4  is a view showing the condition after completion of deployment of the air bag module according to the present invention.  FIG. 5  is a plan view showing an exploded condition of a flap unit of the air bag module according to the present invention.  FIG. 6  is a deployment view showing an assembled condition of the flap unit of the air bag module according to the present invention.  FIG. 7  is a deployment view of the condition during initial deployment of the flap unit of the air bag module.  FIG. 8  is a deployment view showing the condition after completion of deployment of the air bag module according to the present invention.  
      The air bag module according to the present invention is a passenger air bag among air bag modules of various types, which comprises: an air bag housing  60  installed on an instrument panel  50  opposite to a passenger&#39;s seat; an inflator  62  installed on an inner rear part of the air bag housing  60  for supplying an expanding gas; a cushion  64  accommodated at an inner front part of the air bag housing, folded a plural number of times, and provided with an inlet portion  64 ′ at the inflator  62  for intaking the expanding gas from the inflator  62 ; a cushion retainer  66  for securing the inlet portion  64 ′ of the cushion  64  to the air bag housing  60 ; and a flap unit  70  for improving OOP capability.  
      The cushion retainer  66  is provided with studs  65  which are disposed within the cushion  64  and penetrate through the air bag housing  60  to be screwed onto stud nuts  67  on the outer side of the air bag housing  60 , so that the inlet portion  64 ′ of the cushion  64  can be secured to the air bag housing  60 .  
      The flap unit  70  includes a first flap  80  for covering one side of the cushion  64  and a second flap  90  disposed in the opposite side of the first flap  80  from the cushion  64  for covering the other side of the cushion  64 , configured so as to be torn gradually by an expansion pressure of the cushion  64  and having a cut-out portion  92  coupled to the first flap  80 .  
      The first flap  80  consists of a securing portion  82  secured to the air bag housing  60  and a cover portion  84  extending from the securing portion  82  of the first flap  80  to cover one side of the cushion  64  and part of the cut-out portion  92  of the second flap  90 .  
      The securing portion  82  of the first flap  80  has stud holes  81 , which are disposed between the inlet portion  64 ′ of the cushion  64  and the air bag housing  60  for allowing the studs  65  to penetrate through, so that it can be secured to the air bag housing  60  through the cushion retainer  66 .  
      Of the cover portion  84  of the first flap  80 , a region  84 ′ covering part of the cut-out portion  92  of the second flap  90  is formed such that its width W 1  is smaller than the width W 2  of the other regions, and sewn to the cut-out portion  92  of the second flap  90  so that the first flap  80  and the second flap  90  can be sewn and coupled to each other.  
      Of the cover portion  84  of the first flap  80 , a region  84 ′ covering part of the cut-out portion  92  of the second flap  90  overlaps the outer side of the cut-out portion  92  of the second flap  90 .  
      The second flap  90  consists of a securing portion  94  secured to the air bag housing  60 , a cover portion  96  extending from the securing portion  94  of the second flap  90  for covering the other side of the cushion  64  and a folding portion  98  extending from the cover portion  96  to be folded at least once and having the cut-out portion  92 .  
      The securing portion  94  of the first flap  90  has stud holes  91 , which are disposed between the inlet portion  64 ′ of the cushion  64  and the air bag housing  60  for allowing the studs  65  to penetrate through, so that it can be secured to the air bag housing  60  through the cushion retainer  66 .  
      The folding portion  98  of the second flap  90  is folded inward toward the second flap  90  and disposed between the front surface of the cushion  64  accommodated in the air bag housing  60  and the first flap  80 .  
      The cut-out portion  92  of the second flap  90  is segmented from the other regions of the second flap by a cutting line  100  formed in a widthwise direction of the second flap  90  and two tear lines  102  and  104  connected to the cutting line, respectively, and formed at a predetermined length in a lengthwise direction of the second flap  90 .  
      The two tear lines  102  and  104  of the second flap  90  may extend from the cutting line  100  of the second flap  90  up to the free end  90 ′ of the second flap  90  which is the end opposite to the securing portion  94  of the second flap  90 .  
      The two tear lines  102  and  104  of the second flap  90  may be formed perpendicular to the cutting line  100  of the second flap  90 .  
      The cut-out portion  92  of the second flap  90  can be easily tuned according to the length, spacing, etc. of the cutting line  100  of the second flap  90  and the two tear lines  102  and  104  of the second flap  90 .  
      The cut-out portion  92  of the second flap  90  is sewn and coupled to the first flap  80  at the side of the cutting line  100  of the second flap  90  in the lengthwise direction of the second flap  90  so that the two tear lines  102  and  104  of the second flap  90  can be torn from the cutting line  100  of the second flap  90  by an expansion pressure of the cushion  64 .  
      The operation of the thus-constructed air bag module according to the present invention will now be described in detail.  
      In such a state as illustrated in FIGS.  2  to  6 , when an expanding gas is supplied into the cushion  64  from the inflator  62 , the cushion  64  starts to inflate as the expanding gas fills the cushion  6 .  
      At this time, as illustrated in FIGS.  3  to  7 , the cut-out portion  92  of the second flap  90  is gradually torn toward the free end  90 ′ of the second flap  90  by an expansion pressure of the cushion  64 , starting from the cutting line  100  of the second flap  90  along the two tear lines  1012  and  104  of the second flap  90 .  
      As the cut-out portion  92  of the second flap  90  is torn, the folding portion  98  of the second flap  90  is gradually released to deploy the cushion  64  gradually toward a passenger&#39;s seat. Then, as illustrated in FIGS.  4  to  8 , once the folding portion  98  of the second flap  90  is completely released, the cushion is expanded to its full shape, thereby protecting the occupant.  
      At this point, the initial deployment of the cushion  64  is suppressed before the folding portion  98  of the second flap  90  is released as the cut-out portion  92  of the second flap  90  is torn, and part of the expansion pressure of the cushion  64  is absorbed as the cut-out portion  92  of the second flap  90  is torn, thereby enabling the cushion  64  to be expanded to its full shape, with the expansion gas uniformly filled in the cushion  64 .  
      Although these embodiments have been described with respect to the passenger air bag module, the flap unit of the present invention is also applicable to a drive air bag or a side air bag.  
      The thus-constructed air bag module according to the present invention suppress the deployment of the cushion as the cut-out portion of the second flap is torn during deployment of the cushion by having at the second flap the cut-out portion coupled to the first flap and gradually tearable by an expansion pressure of the cushion, the first and second flaps being coupled to each other. Thus, the air bag module can improve OOP capability since it has a higher binding force than the conventional flaps using a friction force.  
      Furthermore, in the present invention, the cutting line and the tear lines are formed on the second flap so as to tear the cut-out portion of the second flap and the force of suppressing the deployment of the cushion can be easily tuned by the first and second flaps by adjusting the length, spacing, etc. of the cutting line and tear lines of the second flap. Thus, this makes it easy to control dimensions and judge compatibility through a naked eye test.  
      Furthermore, in the present invention, the first and second flaps do not need to be coated for acquiring a friction force, thus making it possible to reduce the cost, and the folding portion is provided only on the second flap, which can decrease the length of the first flap as compared to the conventional art, thus making it possible to reduce the cost.  
      Furthermore, in the present invention, the folding portion is provided only on the second flap, so only the second flap needs to be folded, thereby improving workability.