Abstract:
In folding an air bag, the air bag is folded in a first direction and a counter first direction to form a loosing portion in a center area of the air bag at a side opposite to the occupant. Then, the air bag is folded in a second direction and a counter second direction perpendicular to the first and counter first directions, and the air bag is folded in the first direction and the counter first direction. The air bag can smoothly deploy upon actuation of an air bag device, and can securely and sufficiently restrain an occupant.

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT 
     The present invention relates to a method of folding an air bag which is deployed to protect an occupant when a vehicle comes into collision. More particularly, the present invention discloses a method of folding an air bag which can provide suitable deployment of the air bag to securely and sufficiently restrain an occupant and which is improved to provide smooth deployment of the air bag. 
     The present invention can be applied to any type of air bags for a driver, a front passenger and a rear passenger. 
     One of conventional methods of folding an air bag in which the side edges of the air bag are folded toward an occupant has the following problems. In the initial stage of the deployment, a central portion of the air bag contacting an inflator is rapidly inflated, so that a mass of folded portions is pushed out of the cover toward the occupant. In the final stage of the deployment, the air bag is inflated forward at a high speed, so that the mass of folded portions is further pushed forward. Therefore, there is a fear that the occupant is subjected to receive a pressure due to the folded portion of the air bag. 
     The present invention has been made in order to solve the above problem, and an object of the invention is to provide a method of folding an air bag which can provide suitable deployment of the air bag to securely and sufficiently restrain an occupant. 
     Another object of the invention is to provide a method of folding an air bag which is improved to provide a smooth deployment. 
     Further objects and advantages of the invention will be apparent from the following description of the invention. 
     SUMMARY OF THE INVENTION 
     In order to solve the above-described problems, the first aspect of the present invention provides a method of folding an air bag comprising a front panel on an occupant side and a rear panel on a side opposite to the occupant, wherein the air bag is folded by the combination of vertical, lateral and vertical directions or by the combination of lateral, vertical and lateral directions. 
     This enables the folded air bag to have a loosing portion in the vertically or laterally direction, thereby providing a suitable deployment of the air bag to securely and sufficiently restrain an occupant and improving the smooth deployment. 
     In the method of folding the air bag as mentioned above, it is preferable that side edges of the air bag are rolled up or folded in bellows on the side opposite to the occupant. The air bag can be folded in a square or rectangular shape so that the air bag can be securely accommodated in a box-like cover. In addition, the air bag is deployed relatively equally as a whole from the central portion thereof. The rolls or folded portions of the side edges of the air bag are prevented from advancing directly toward the occupant. 
     The second embodiment of the present invention provides a method of folding an air bag comprising a front panel on an occupant side and a rear panel on the side opposite to the occupant, which comprises (a) a step of forming a loosing portion to extend vertically or laterally about a center portion of the air bag, and (b) a step of rolling or folding like bellows upper, lower, left and right side portions of the air bag on the side opposite to the occupant. 
     The loosing portion in the center portion of the air bag prevents the air bag as a whole from easily rapidly projecting outwardly, so that the air bag starts to inflate from the central portion thereof gradually. The operation of the edges rolled up or folded in bellows are the same as the case of the aforementioned first embodiment. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS.  1 (A)- 1 (F′) are views illustrating one example of a folding process according to a method of folding an air bag of the present invention; 
     FIGS.  2 (A)- 2 (C) are views illustrating the configurations of the air bag during the deployment in the order of time, wherein FIG.  2 (A) shows a state before deployment of the air bag, FIG.  2 (B) shows a state in an initial stage of the deployment, and FIG.  2 (C) shows a state in a final stage of the deployment; 
     FIG. 3 is a side view showing an alternative example of the method of folding the air bag of the embodiment shown in FIGS.  1 (A)- 1 (F′); and 
     FIG. 4 is a side view showing a still alternative example of the method of folding the air bag of the embodiment shown in FIGS.  1 (A)- 1 (F′). 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Hereinafter, the present invention will be described with reference to attached drawings. 
     FIGS.  1 (A) though  1 (F) are views illustrating the process of folding an air bag according to one embodiment of the present invention. FIG.  1 (A) is view of the air bag  1 , which is substantially circular in its plan view, taken at a side of a front panel  3 . The air bag  1  comprises the front panel  3  and a rear panel  5  which are strongly connected to each other around the peripheries thereof, for example by sewing, adhering or welding. The rear panel  5  has a gas inlet  7  formed in the center thereof. Connected to the gas inlet  7  via a retainer  31  is an inflator  33  which generates deployment gas. 
     FIGS.  1 (B) and  1 (B′), which are a plan view and a side view, respectively, show a first stage of a folding process, wherein the air bag  1  is folded to have a loosing portion  11  vertically extending at a center area thereof. That is, two folded lines  15 ,  15 ′ are set on both sides of the vertical center area of the air bag to extend parallel to each other, and the both sides of the air bag are folded along the folded lines  15 ,  15 ′ toward the center of the air bag, i.e. in a first direction and a counter first direction, respectively. Then, both side portions outside of the folded lines  15 ,  15 ′ are folded along folded lines  13 ,  13 ′ toward the outside, i.e. in a counter first direction and a first direction, respectively. Namely, a right side of the air bag is folded in the right or counter first direction while a left side of the air bag is folded in the left or first direction. In this way, the vertically extending loosing portion  11  is formed at a side opposite to an occupant. 
     As shown in FIGS.  1 (C),  1 (C′) and  1 (D),  1 (D′), the upper and lower side portions of the air bag  1  are rolled up on the side opposite to the occupant to form rolls  21 ,  23 . Incidentally, FIGS.  1 (C′) and  1 (D′) are side views of FIGS.  1 (C) and  1 (D), respectively. As shown in FIG.  1 (D′), in which the left side is the occupant side and the right side is the side opposite to the occupant, the lower roll  21  is rolled toward the center thereof in the counter-clockwise, i.e. counter second, direction and the upper roll  23  is rolled toward the center thereof in the clockwise, i.e. second, direction. This is because the air bag expands in such a manner that the center of each roll leans toward the side opposite to the occupant (see FIG.  2 (C)) when the rolls become loose during the deployment of the air bag. 
     After that, as shown in FIGS.  1 (E),  1 (E′),  1 (F) and  1 (F′), the left and right side portions of the air bag  1  are rolled up on the side opposite to the occupant to form rolls  25 ,  27 , so that the rolls  25 ,  27  are positioned on the central loosing portion  11 . As a result, the air bag  1  is formed in a small square shape as shown in FIG.  1 (F). In this state, the retainer  31  and the inflator  33  are connected to the air bag  11  and are accommodated in a cover  35 . 
     The description will be made as regard to the configurations of the air bag folded as shown in FIGS.  1 (A) through  1 (F′) during its deployment. FIGS.  2 (A) through  2 (C) are views showing the configurations of the air bag of FIGS.  1 (A)- 1 (F′) in the order of time. FIG.  2 (A) shows a state before deployment of the air bag, FIG.  2 (B) shows a state of an initial stage of the deployment, and FIG.  2 (C) shows a state of a final stage of the deployment. 
     In the state before the deployment shown in FIG.  2 (A), the air bag  1  which is folded in a square or rectangular shape is accommodated in the box-like cover  35 . The gas inlet  7  positioned toward the loosing portion  11  at the central portion of the air bag  1  is fixed to the inner periphery of the retainer  31 . The inflator  33  is disposed in the center of the retainer  31 . 
     As the inflator  33  is ignited, the loosing portion  11  at the central portion of the air bag  1  is first inflated while the side rolls  21 ,  23 ,  25 ,  27  still stay in the cover  35  as shown in FIG.  2 (B). In the final stage of the deployment, the central portion of the air bag  1  is further inflated and the folded portions or the rolls of the side portions are accordingly inflated, so that the deployment of the air bag  1  is relatively equal and smooth, as a whole. 
     Hereinafter, an alternative example of the folding method according to the embodiment of FIGS.  1 (A)- 1 (F′) will be described. 
     Though the side portions of the air bag are rolled up in the embodiment of FIGS.  1 (A)- 1 (F′), the right and left, and upper and lower side portions may be folded in bellows  21 ′,  25 ′,  27 ′, as shown in FIGS. 3 and 4. 
     According to the method of folding the air bag of the invention, the combination of foldings vertically, laterally and vertically or the combination of foldings laterally, vertically and laterally is employed as the folding and/or rolling directions, so that the loosing portion exists on the air bag vertically or laterally. 
     Since the side portions are rolled up or folded in bellows on the side opposite to the occupant, the air bag can be folded in a square or rectangular shape, so that the air bag can be securely accommodated in the box-like cover. In addition, the air bag is deployed relatively equally as a whole from the central portion thereof. The rolls or folded portions at the side portions of the air bag are prevented from advancing directly toward the occupant. 
     The loosing portion extending laterally or vertically across the air bag on the side opposite to the occupant prevents the air bag as a whole from easily rapidly projecting, so that the air bag starts to inflate from the central portion thereof. 
     As apparent from the above description, the present invention can provide a method of folding an air bag which can provide suitable deployment of the air bag to securely and sufficiently restrain an occupant and which is improved in smooth deployment. 
     While the invention has been explained with reference to the specific embodiments of the invention, the explanation is illustrative, and the invention is limited only by the appended claims.