Head protecting airbag device

This application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2012-079982 filed on Mar. 30, 2012, the entire content of which is hereby incorporated herein by reference in its entirety.

1. Technical Field

The present invention relates to a head protecting airbag device. More particularly, the invention relates to a head protecting airbag device in which an airbag expands and develops like a curtain parallel with pillars and door windows arranged in each side wall of a vehicle body from its front end to its rear end between these things and a driver or a passenger when, for example, the vehicle encounters a sideways collision or turns over on its side.

2. Related Art

Among head protecting airbag devices is a device in which a side airbag expands and develops like a curtain. The side airbag is folded and housed, so as to extend in the vehicle longitudinal direction, in a cover mole which is located at the top of each side wall of the compartment so as to extend from its front end to its rear end. In a car which is equipped with this kind of head protecting airbag device, when, for example, the car encounters a sideways collision or occurrence of such an accident is predicted by activation of a collision prediction sensor (hereinafter no reference will be made of this collision prediction mechanism), the side airbag expands so as to cover the front pillar which is located at the front-right or left corner of the vehicle, the front seat window, the center pillar, the rear seat window, and the rear pillar and develops downward like a curtain between these things and a driver or a passenger. Thus, the side airbag restricts a sideways movement of the head of the driver or passenger and thereby protects the head.

This kind of head protecting airbag device is attached to a roof side rail portion of a vehicle body in a folded state. However, since the head protecting airbag device is long even in the folded state, work of attaching it takes time. And hanging-down of those portions, located between hanging points, of the folded airbag lowers the efficiency of attaching work. Furthermore, the airbag might fail to develop in a proper manner at the occurrence of a collision. In view of the above, an airbag device has bee proposed in which a folded airbag is supported by part of an inflator via a support member (JP-A-2003-306119).

The invention relates to a head protecting airbag device. The head protecting airbag device includes an airbag (i) in which plural expansive support portions are arranged from a front portion to a rear portion of a vehicle so as to communicate with each other, (ii) which is fixed to and held by a portion of a vehicle body in a folded state so as to extend along a top edge of a side wall of the vehicle and (iii) which develops like a curtain parallel with an inner surface of the side wall of the vehicle while the expansive support portions are expanded by a gas that is introduced from an inflator which operates when a collision is detected or predicted. An airbag support belt is connected to a portion, in close proximity to a top edge of the airbag and close to an attachment position of the inflator, of the airbag. The inflator is attached to the airbag in such a manner that the airbag support belt is wound around a circumferential surface of the inflator and a tip portion of the airbag support belt is fixed to the inflator to thereby cause the inflator to support a part of the airbag.

In the head protecting airbag device, the airbag support belt has an opening. The airbag support belt is wound in one or more turns around the circumferential surface of the inflator in such a manner that a tip portion of the airbag support belt passes through the opening.

In the head protecting airbag device, the inflator has a locking unit. The airbag support belt is fixed to the inflator by locking, on the locking unit, a locking hole which is formed in a tip fixing portion of the airbag support belt.

In the head protecting airbag device, a position of the opening in the airbag support belt is set according to a size of the inflator so that tension of the winding of the airbag support belt around the inflator is adjusted.

FIG. 1 is a schematic front view showing the configuration of a curtain airbag device (head protecting airbag device) according to an embodiment of the present invention.

FIGS. 2A and 2B are schematic front views of the curtain airbag device in a state that an airbag shown in FIG. 1 is folded.

FIGS. 3A , 3 B, and 3 C are enlarged views showing how an airbag support belt is wound on an inflator.

FIGS. 4A , 4 B and 4 C are more enlarged views showing how the airbag support belt is wound on the inflator.

FIGS. 5A , 5 B and 5 C are sectional views showing how the airbag support belt is wound on the inflator.

FIGS. 6A , 6 B and 6 C are schematic front views illustrating embodiments in which the attachment position of the airbag support belt is set differently according to the attachment position where the inflator.

Head protecting airbag devices according to plural embodiments as the best mode for carrying out the invention will be hereinafter described with reference to the accompanying drawings.

[Embodiments]

FIG. 1 is a schematic front view a head protecting airbag device (hereinafter referred to as a curtain airbag device) 10 according to an embodiment in a state that an airbag 10 A has been expanded in a prescribed manner approximately parallel with the right side wall of a vehicle and developed in a curtain-like shape. Although the curtain airbag device 10 is provided on both of the left side and the right side in the vehicle, the concept of the invention will be described below using only the curtain airbag device 10 provided on the right side.

The airbag 10 A which is the main constituent member of the curtain airbag device 10 shown in FIG. 1 has approximately the same shape as airbags used in known curtain airbag devices (reference symbol 10 A denotes the airbag as a whole). More specifically, the airbag 10 A is formed by laying on each other and sewing together, generally alongside their outer circumferences, two pieces of base cloth having approximately the same shape that were cut out so as to extend a long distance from a front pillar A to a rear pillar C of the vehicle body in the front-rear direction. The two pieces of base cloth are sewed together to form an outer boundary line 25 which has a prescribed shape and defines an expansive support portion 20 , a gas introduction passage 21 , and an unexpansive portion 22 . The expansive support portion 20 is divided into a front seat expansive support portion 20 F and a rear seat expansive support portion 20 R, and the unexpansive portion 22 is located between them.

The front seat expansive support portion 20 F is defined by the outer boundary line 25 so as to completely cover a range of the slidable front seat that depends on the physique of a driver/passenger sitting there, under the gas introduction passage 21 . Likewise, the rear seat expansive support portion 20 R is defined by the outer boundary line 25 so as to completely cover a range of the rear seat that depends on the physique of a passenger sitting there.

The airbag 10 A is also formed with a gas inlet 10 c at a halfway position in the longitudinal direction in such a manner that it projects obliquely upward/rearward. An inflator 5 is connected to the gas inlet 10 c . When acceleration that is higher than a threshold value is detected by a vehicular acceleration sensor (not shown) at the time of (prediction of) a sideways collision or the like, the inflator 5 produces a reaction gas explosively as a result of ignition of chemicals housed inside the inflator 5 . When the gas is introduced into the airbag 10 A through the gas inlet 10 c , the front seat expansive support portion 20 F and the rear seat expansive support portion 20 R are expanded, whereby the airbag 10 A pushes open a lid that covers roof side rails (not shown) and develops downward approximately at a constant speed like a curtain from the top edge of the vehicle side wall over its length in the vehicle front-rear direction.

How the curtain airbag device 10 is attached will be described below with reference to FIGS. 2A and 2B . FIG. 2A shows a state that the airbag 10 A is folded (the airbag 10 A in an expanded state as shown in FIG. 1 is indicated by an imaginary line (two-dot chain line). To maintain this folded state, folding belts 6 are disposed at prescribed intervals in the longitudinal direction and wound around the airbag 10 A. The folding belts 6 are thin cloth members having such strength as not to be broken usually and to be broken when they receive prescribed tension due to expansion of the airbag 10 A. Although in the embodiment the airbag 10 A is folded in roll form, other shapes such as a bellows band shape can be employed as long as they allow the airbag 10 A to develop instantaneously when it is expanded.

As shown in FIG. 1 , the curtain airbag device 10 has, as members for attaching it to the vehicle body, a front attachment belt 12 which is connected to a tip portion 11 a of a tip unexpansive portion 11 and plural attachment tabs 13 which project from a top edge 10 b which extends in the longitudinal direction. The front attachment belt 12 is fixed, with a bolt, to a body anchor portion (not shown) of the front pillar A. The tabs 13 are fixed to anchor portions (not shown) formed on the roof side rails (not shown) which extend in the vehicle front-rear direction between the upper ends of the front pillar A, a center pillar B, and the rear pillar C. As shown in FIG. 2B , the curtain airbag device 10 which is a long member and is attached to the vehicle body in the above-described manner is housed in the longitudinal lid (not shown) which covers the roof side rails and function, in terms of design, as a partition mole located between the ceiling and the side wall of the vehicle.

FIG. 2A shows a state before attachment of the curtain airbag device 10 to the vehicle body. In this state, the airbag 10 A and the inflator 5 have not yet been integrated together by means of an airbag support belt 15 . As shown in FIG. 2A , a generally inverted-U-shaped retainer 7 is attached to the inflator 5 which is connected to a top portion, located approximately at the center in the longitudinal direction, of the airbag 10 A. The retainer 7 is an attachment member for attaching the inflator 5 which is relatively heavy to the vehicle body stably in attaching the curtain airbag device 10 to the vehicle body. In the embodiment, as shown in FIG. 2B , the airbag support belt 15 is used to integrate the inflator 5 with the airbag 10 A in a folded state. As shown in FIG. 2B , when the inflator 5 and the airbag 10 A are integrated together by means of the airbag support belt 15 , attachment holes 7 a of the retainer 7 are kept exposed, that is, they are not hidden behind the airbag 10 A. Therefore, in attaching the curtain airbag device 10 to the vehicle body, positioning of the attachment holes 7 a of the retainer 7 and work of attaching the retainer 7 can be performed easily, whereby the efficiency of the airbag attaching work can be increased greatly. Furthermore, after attachment of the inflator 5 and the curtain airbag device 10 , a portion, distant from the folding belt 6 , of the folded airbag 10 A can be prevented from hanging down. Still further, since the inflator 5 is connected strongly to the top portion of the airbag 10 A, the degree of swinging of the airbag 10 A can be reduced when the inflator 5 operates and the airbag 10 A is developed.

The structure of the airbag support belt 15 , which is an important feature of the invention, will be described below. As shown in FIGS. 1 and 2A , the airbag support belt 15 used in the embodiment is sewed strongly on a top unexpansive portion of the airbag 10 A that is close to the rear end of the inflator 5 that is connected to the gas inlet 10 c , so as to extend downward approximately perpendicularly to the top edge 10 b of the airbag 10 A. The airbag support belt 15 is a long and narrow belt formed by laying on each other two pieces of cloth made of the same material as the airbag 10 A. In the embodiment, as shown in FIG. 4A , the airbag support belt 15 is composed of a belt main body 15 a that is about 30 mm in width and 200 mm in length (as measured from the sewed portion) and a tip fixing portion 15 b which is bent from the belt main body 115 a so that the airbag support belt 15 is approximately L-shaped as a whole. To integrate the two pieces of cloth together, two reinforcement sewing lines 15 c are formed in the longitudinal direction of the airbag support belt 15 . Furthermore, as shown in FIG. 4A , an opening 16 which is long in the lateral direction is formed in the airbag support belt 15 at a position that is close to the portion that is sewed on the airbag 10 A.

When wound around the outer circumferential surface of the inflator 5 , the tip portion of the airbag support belt 15 is caused to pass through the opening 16 , whereby the second turn can be wound on the inflator 5 without being shifted laterally. It is preferable that the opening 16 be shaped so as to give only small resistance to the airbag support belt 15 when it is caused to pass through the opening 16 . More specifically, taking the ease of positioning and winding work into consideration, it is preferable that the opening 16 have an elliptical or rectangular shape that is short in the longitudinal direction of the airbag support belt 15 . To secure its strength, the airbag support belt 15 may be formed by laying on each other three or more pieces of cloth that is made of the same material as the airbag 10 A. As a further alternative, the airbag support belt 15 may be may be made of thick (pieces of) cloth. It is even possible to use an elastic material or the like, in which case the airbag support belt 15 can be fastened to the inflator 5 more reliably utilizing it elongation.

A locking hole 17 is formed in the tip fixing portion 15 b . After completion of winding of the airbag support belt 15 on the inflator 5 , the tip fixing portion 15 b can be fixed to the inflator 5 by hooking the locking hole 17 on a locking projection 8 which is provided in the inflator 5 . It is preferable that the tip fixing portion 15 b be offset from the width range of the belt main body 15 a so as not to obstruct work of winding the airbag support belt 15 in plural turns. To this end, in the embodiment, the tip fixing portion 15 b is bent from the belt main body 15 a and the locking hole 17 is formed in the thus-bent tip fixing portion 15 b. Conversely, part of the belt main body 15 a may be cut out so that the belt main body 15 a can avoid the locking projection 8 when wound on the inflator 5 .

Next, a procedure for integrating the inflator 5 with the airbag 10 A using the airbag support belt 15 having the above-described structure will be described with reference to FIG. 3A to FIG. 5C .

FIGS. 3A and 3C are schematic views as stereographic, enlarged versions of parts, including the inflator 5 and the inflator-attaching portion of the airbag 10 A, of FIGS. 2A and 2B , respectively. FIG. 3A shows a state before integration of the inflator 5 and the airbag 10 A. In the embodiment, the airbag 10 A is folded in roll form except a portion close to the gas inlet 10 c because the inflator 5 and a diffuser (not shown) that is attached to the tip of the inflator 5 are inserted in the gas inlet 10 c . Therefore, this portion of the airbag 10 A is integrated with the inflator 5 by means of the airbag support belt 15 . FIG. 3B shows how this portion of the airbag 10 A is integrated with the inflator 5 by means of the airbag support belt 15 .

The procedure for integrating the inflator 5 with the airbag 10 A using the airbag support belt 15 will be described in a more specific manner with reference to FIGS. 4A , 4 B, 4 C 5 A, 5 B and 5 C. As shown in FIG. 3A , in the state that the airbag 10 A is folded, the inflator 5 extends along the gas inlet 10 c of the airbag 10 A obliquely away from the folded portion of the airbag 10 A. Therefore, the soft gas inlet 10 c of the airbag 10 A is deformed so as to become approximately parallel with the airbag 10 A (see FIG. 4A ) and, in this state, the airbag support belt 15 is wound around the inflator 5 (see FIG. 4A ). More specifically, as shown in FIGS. 3B and 4B , the airbag support belt 15 is raised above its proximal portion 15 d and wound around the circumferential surface of the inflator 5 in one turn in such a manner as to be first laid on that side surface of the inflator 5 which is located on the opposite side to the side where the airbag support belt 15 is attached to the airbag 10 A. When the unwound portion of the airbag support belt 15 has returned to below the inflator 5 , the tip portion of the airbag support belt 15 is narrowed and inserted through the opening 16 which is located close to the proximal portion 15 d and the unwound portion of the airbag support belt 15 is pulled so as to pass through the opening 16 . Then, the unwound portion of the airbag support belt 15 is wound on its already wound turn, and the locking hole 17 of the tip fixing portion 15 b is hooked on the locking projection 8 of the inflator 5 (see FIG. 4C ).

FIGS. 5A , 5 B and 5 C are schematic sectional views which correspond to FIGS. 4A , 4 B and 4 C, respectively, and also illustrate how the airbag support belt 15 is integrated with the inflator 5 . The relationship between the length of the airbag support belt 15 and the diameter of the inflator 5 can be understood from FIGS. 5A , 5 B and 5 C. The airbag support belt 15 is bent upward from the state of FIG. 5A and wound around the inflator 5 in one turn in such a manner as to be first laid on that side surface of the inflator 5 which is located on the opposite side to the side where the airbag support belt 15 is attached to the airbag 10 A. In this state, the opening 16 of the airbag support belt 15 is located under the inflator 5 . The tip portion of the airbag support belt 15 is let pass through the opening 16 , and the unwounded portion of the airbag support belt 15 is wound on the inflator 5 as a second turn along the same route as the first turn was wound (see FIG. 5B ). Then, the locking hole 17 of the tip fixing portion 15 b of the airbag support belt 15 is hooked on the locking projection 8 which is located at approximately the same circumferential position as the tip of the airbag support belt 15 should be located when ½ to ¾ of the second turn has been wound (see FIG. 4C ).

As shown in FIGS. 5A , 5 B and 5 C, by setting the length of the airbag support belt 15 according to the diameter of the inflator 5 and the position of the locking projection 8 formed on its surface, the inflator 5 can be integrated with the folded airbag 10 A sufficiently closely (see FIGS. 3C , 4 C, and 5 C).

More specifically, it is preferable that the length (winding length) of the airbag support belt 15 , the longitudinal position of the opening 16 which is located close to the proximal portion 15 d , and the longitudinal position and the offset of the locking hole 17 of the tip fixing portion 15 b be set taking into consideration the diameter (or outer circumferential length) of the cylindrical inflator used and the position of the locking projection 8 . As long as these parameters are set properly, prescribed tension acts on the airbag support belt 15 when the tip fixing portion 15 b of the airbag support belt 15 is hooked on the locking projection 8 formed on its surface, the inflator 5 , whereby the inflator 5 can be integrated with the airbag 10 A closely.

Although in the above embodiment the locking projection 8 is formed on a portion of a clamp band 9 which is attached to the outer circumferential surface of the inflator 5 , a portion of the retainer 7 which is attached to the inflator 5 may be provided with a projection-shaped locking member. As a further alternative, the airbag support belt 15 may be fastened to the inflator 5 in a similar manner by forming a locking portion on another kind of fastening member such as a bracket. In any case, it is preferable that the locking hole 17 of the tip fixing portion 15 b be formed so as to conform to the shape of the counterpart locking member to prevent the locking hole 17 from coming off easily.

FIGS. 6A , 6 B and 6 C illustrate embodiments in which the attachment position of the airbag support belt 15 is set differently according to the position where the inflator 5 is attached to the airbag 10 A. FIG. 6A illustrates an embodiment in which the gas inlet 10 c of the airbag 10 A is located between the center pillar B and the rear pillar C. In this case, the attachment position of the airbag support belt 15 is set above the rear seat expansive support portion 20 R, whereby the entire rear seat expansive support portion 20 R of the airbag 10 A is allowed to develop smoothly.

FIG. 6B illustrates an embodiment in which the inflator 5 is attached to a rear end portion of the airbag 10 A so as to extend approximately horizontally. This prevents the rear end portion of the airbag 10 A from interfering with the rear pillar C when it develops.

FIG. 6C illustrates an embodiment in which the airbag 10 A has a three-stage structure and is long in the vehicle front-rear direction. Two inflators 5 are arranged in the front-rear direction. In this case, the relationships between the attachment positions of the two inflators 5 and the positions where two respective airbag support belts 15 are attached to the airbag 10 A may be similar to those shown in FIGS. 6A and 6B , respectively.

Whereas in each of the above embodiments the airbag support belt 15 is a separate band-shaped member having a prescribed length which is sewed on the airbag 10 A at a prescribed position that is close to its top edge 10 b , other attaching means are possible. For example, the airbag support belt 15 may be bonded to a bonding margin, wide enough to secure prescribed bonding strength, of the airbag 10 A. Or the airbag support belt 15 may be attached to the airbag 10 A using a support piece or any of other attaching means that do not damage the material of the airbag 10 A. As a further alternative, the airbag support belt may be formed by cutting the pieces of base cloth of the airbag, in which case the airbag support belt is part of the airbag.

The invention is not limited to the above embodiments, and various modifications are possible without departing from the scope of the claims. That is, the technical scope of the invention encompasses implementations as combinations of technical means that are modified as appropriate without departing from the scope of the claims.