JPH0752736A - Expansive structural body of seat belt device - Google Patents

Abstract

PURPOSE:To prevent a tube, constituting an expansive structural body, from being suddenly expanded at a fastening end. CONSTITUTION:A joint part to a webbing 15 of a tip closing part 12a of a tube 12 is installed in close vicinity to the joint part with the webbing 15 of a nitted fabric 13. When the tube 12 is expanded, it is expanded so as to make an outer surface of the tip closing part 12a adhere to an inner surface of the nitted fabric 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inflatable structure of a seat belt device, and more particularly to a portion of the seat belt device which is incorporated in a part of the seat belt device and inflates at the time of a collision to retract or inflate the webbing of the seat belt device. The present invention relates to an inflatable structure of a seat belt device capable of restraining and protecting the movement of an occupant.

[0002]

2. Description of the Related Art In recent years, various developments have been made in order to improve the occupant restraint performance of a seat belt device installed in an automobile. As an example, part of the webbing is formed into an inflatable bag shape, and during normal wearing, this bag shape part is folded into a fan shape and weak adhesion is applied to keep it in a band shape (fan hold type), and the folded part is a fastener. There has been proposed a seat belt device in which a belt-like shape is held by a locking means such as the like, and the bag-shaped portion is inflated and expanded by the gas ejected from the gas generator connected to the webbing when an impact is applied (US See Japanese Patent No. 3,865,398). According to the seatbelt device having the inflatable bag-shaped portion of this kind (hereinafter, referred to as an inflatable seatbelt device), the load acting on the occupant can be dispersed over a wider area than the conventional webbing. It is possible to reduce the load received by the vehicle and further improve safety.

By the way, in the inflatable seat belt device of the type in which the bag-shaped portion is folded to form the belt-shaped belt having the predetermined width as described above, since the folding margin of the bag-shaped portion is thick and bulky, the belt is worn by the occupant at the time of wearing. It is difficult to fit the body and it is difficult to smoothly pass through the slip guide of the pillar anchor. For this reason, the user may feel uncomfortable wearing the belt, and the wearing rate may decrease. Further, since the folded portion is adhered and fixed, there is also a problem that it is difficult for the inflated portion to deploy smoothly even if the jet gas is introduced into the bag-shaped portion during inflation and deployment.

Therefore, the applicant has already proposed an inflatable seat belt device which solves these problems (Japanese Patent Application Nos. 4-210353 and 5-7862).
(See No. 3 application). In the above-mentioned application, the applicant has adopted a woven fabric structure in which a bag-shaped portion having an elastic bag-shaped body inside is constructed with a knitted fabric structure, and a weft yarn (weft yarn) is sufficiently extended in this bag-shaped portion ( Hereinafter, in the present specification, the entire bag-shaped portion having an inflatable structure made of this knitted fabric structure will be referred to as an "inflatable structure".), And when the bag-shaped portion is inflated and deployed, the occupant's chest is properly held. The invention which provided the expansion control part so that it could be disclosed was disclosed.

FIG. 10 (a) is an explanatory view showing a schematic structure of the inflatable seat belt device 50 described above.
As shown in the figure, the bag-shaped portion 51 (expansion structure) having a knitted structure incorporated in the shoulder belt of the webbing W is provided near the chest of the occupant M by gas supply from a gas generating means (not shown) that operates at the time of collision. It expands into a spindle shape. According to the present invention, the shoulder belt of the seatbelt device is held in a relatively thin strip shape during normal wearing, and in an emergency, the inflatable structure can be rapidly inflated and deployed to an appropriate shape, The occupants can be effectively restrained and protected.

On the other hand, the applicant has also proposed an invention in which the above-described inflatable expansion structure 51 is provided at the end portion of the webbing W fixed to the fixed portion in the vehicle to form a pretensioner (FIG. 10 (b)). )reference). According to the present invention, the expansion structure is expanded on the basis of the operation signal from the sensor that has detected the collision, and at this time, the entire length of the expansion structure 51 is shortened to be used for the continuous webbing. Shoulder belt 5
The two parts and the lap belt 53 part can be instantaneously retracted in the directions of arrows A and B in the drawing to operate as a pretensioner. According to the present invention, the seat belt device can have a pretensioner function with a simple structure. With this pretensioner, the occupant can be restrained to the seat before the inertial force at the time of collision acts on the occupant, and the impact on the occupant can be minimized.

FIG. 11A shows a webbing W as an expansion structure 51 of the inflatable seat belt device described above.
1 schematically shows an example in which a part of the shoulder belt 52 is a tubular knitted fabric 55, and a bag-shaped rubber tube is inserted therein. As shown in the figure, the shoulder belt 52 is composed of the slip guide S, and the tube 54 made of a silicone rubber thin film is adhered to the end of the webbing W while maintaining airtightness in a flat state. . The tube 54 made of silicone rubber having a large elastic elongation has a flat envelope shape, and when gas is introduced into the tube 54 without restraint, the tube 54 can expand like a balloon.

The tube 54 is housed in a tubular, flat knitted cloth 55 knitted to a slightly larger size. This knitted fabric 55 is made of a circular knit using polyester processed yarn, and the knitted fabric 55 made of this circular knit is difficult to stretch in the longitudinal direction of the belt (the warp direction of the knitted fabric: the warp direction) and has a tubular shape. It has the property of being easily stretched in the direction in which the circumference of the circle increases (the weft direction of the knitted fabric: the weft direction). Further, the cloth cover 56 is attached so as to cover the entire tubular knitted cloth 55.

FIG. 11 (b) schematically shows a state in which a predetermined gas internal pressure is applied to the belt portion of the inflatable seat belt device having such a structure. As shown in the figure, when the tube 54 is expanded by the introduced gas, the knitted cloth 55 made of a circular knit stretches in the lateral direction and expands in a tubular shape. Then, when the predetermined internal pressure acts, the cover 5
Part of the sewing thread in the portion where the cloth of 6 is sewn together is broken.
Then, the seam 56a of the cover 56 expands so as to open the mouth, and the tube 54 wrapped in the circular knitted knitting cloth 55 expands in a spindle shape so as to protrude from the portion. When the internal pressure of the gas acts on the rubber tube and the tube expands in this manner, the bag-shaped knitted fabric structure that wraps the tube adjusts the overall shape to form an elongated spindle shape. In this way, the area of the belt portion in contact with the chest and the like of the occupant is increased, so that the impact applied to the human body is alleviated and the occupant can be effectively protected.

[0010]

By the way, in order to expand the tube 54 of the expansion structure 51, an inert gas generated by a rapid combustion reaction in a gas generator (not shown) is used. At this time, the internal pressure in the tube 54 generated by the introduced gas is P = 2 to 3 kg / when expanded.
It becomes cm ^2, when further restrains movement of the occupant in the belt during a collision rises to P = 5~6kg / cm ^2. In this case as well, the expansion structure must effectively retain its expanded shape. At this time, the above-mentioned tube 54 can behave in a large elastic region with respect to the tensile force applied by the internal pressure, and the knitted fabric structure portion is also in the weft direction (the weft direction of the knitted fabric).
In contrast, it exhibits a sufficient elongation property and can follow the expansion deformation of the tube 54. However, the deformation is restrained at the joining portion where the tube 54 or the knitted fabric 55 is fixed to the webbing with respect to the portion where sufficient elongation can be expected.
Therefore, when the tube 54 or the like expands rapidly, the elongation may change significantly in this portion, and excessive elongation may partially occur in the tube 54.

Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art and to firmly fix the end portion of the inflatable structure incorporated in the seat belt device and inflating at a predetermined timing to the webbing even when inflating. The present invention provides an inflatable structure for a seat belt device as described above.

[0012]

In order to achieve the above object, a first aspect of the present invention is a tubular expander capable of expanding while maintaining airtightness by introducing gas from a gas generating means connected to an open end. A seatbelt device in which the tubular inflatable body is housed inside and a bag-shaped portion that can be inflated and deployed in a substantially spindle shape in accordance with the inflating deformation of the tubular inflatable body is connected to an end portion of the webbing. In the expansion structure, the tubular inflatable body is provided such that a joining portion of the tip closing portion to the webbing is sufficiently close to a joining portion of the bag-like portion to an end portion of the webbing, and the tip closing portion. It is characterized in that the outer surface expands so as to come into close contact with the inner surface of the bag-shaped portion.

A second aspect of the present invention is to accommodate a tubular expander capable of expanding while maintaining airtightness by introducing gas from a gas generating means connected to the opening end, and the tubular expander is housed inside. In the expansion structure of the seat belt device in which the bag-shaped portion that can be expanded and deployed in a substantially spindle shape following the expansion deformation of the tubular expansion body is connected to the end of the webbing, the tubular expansion body is A joining portion of the tip closing portion to the webbing is provided by laminating with a joining portion of the bag-shaped portion with an end portion of the webbing, and the outer surface of the tip closing portion is closely attached to the inner surface of the bag-shaped portion. It is characterized by expanding.

In the second aspect of the present invention, the joining portion of the tip closed portion of the tubular expander to the webbing and the joining portion of the end portion of the webbing of the bag portion are laminated and clamped. It is preferable to sandwich them.

In the first or second aspect of the invention, the bag-shaped portion is covered with a cover having a linear weak portion formed on the surface thereof, and the linear weak portion is broken by an acting internal pressure and expanded into a substantially spindle shape. It is preferable to deploy it.

[0016]

According to the first aspect of the invention, the joining portion of the distal end blocking portion of the tubular expander to the webbing is provided sufficiently close to the joining portion of the bag-shaped portion to the end portion of the webbing, When the tubular inflatable body expands, the outer surface of the tip closing portion is inflated so as to be in close contact with the inner surface of the bag-shaped portion. Therefore, the expansion deformation of the tip closed portion of the tubular inflatable body is caused by the bag-shaped portion. It is restricted by the deformation, and it is possible to prevent damage due to abrupt elongation change.

According to the second aspect of the invention, the joining portion of the distal end blocking portion of the tubular expander to the webbing and the joining portion of the bag portion to the end portion of the webbing are laminated. Since the outer surface of the distal end blocking portion is inflated so as to be in close contact with the inner surface of the bag-shaped portion when the tubular inflatable body expands, expansion deformation of the distal end blocking portion of the tubular expandable body is Restricted by the deformation of the bag-shaped part,
It is possible to prevent sudden changes in elongation.

In the second aspect of the present invention, the joining portion of the tip closed portion of the tubular expander to the webbing and the joining portion of the end portion of the webbing of the bag portion are clamped in a laminated state. By sandwiching, the joint portion can have a simple structure, and the expansion deformation of the distal end blocking portion of the tubular expansion body can be reliably regulated by the deformation of the bag-shaped portion.

In the first or second aspect of the invention, the bag-shaped portion is covered with a cover having a linear weak portion formed on the surface thereof, and the linear weak portion is ruptured by the action internal pressure, and expanded and expanded into a substantially spindle shape. Since this is done, it is possible to realize an appropriate expanded shape without causing sudden deformation of the bag-shaped portion.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an inflatable structure for a seat belt device according to the present invention will be described below with reference to FIGS. FIG. 1 is a vertical cross-sectional view showing a state in which the expansion structure is expanded to a predetermined shape by an introduced gas from a gas generator (not shown) so that the internal structure can be seen.

As shown in the figure, the members (bag filter 11, tube 12, knitted fabric 1) that constitute the expansion structure 10 are shown.
3, cover 14: details will be described later. ) Is rubber coating 21a
The outer peripheral portions of the end fittings 21 are stacked so as to be in close contact with each other. Further, a caulking metal fitting 22 having an inner surface covered with a rubber coating 22a is fitted to the outer peripheral portion thereof. By adopting such an end structure, the expansion structure 1
In No. 0, the airtightness is maintained at the end 10a, and even if the high-pressure reaction gas is rapidly introduced into the expansion structure 10, the end fitting 21 does not separate and break.
Further, a tongue pipe 23 that is inserted into and engaged with a buckle body of a buckle device (not shown) is fixed to the tip of the end fitting 21. In this embodiment, the gas generating means is housed in this buckle device, and the gas generated from the gas generating means is expanded through the gas flow holes 24 formed inside the tongue pipe 23 and the inside of the end fitting 21. It is introduced into the structure 10. Thus, the tongue 3 according to the present embodiment is
The end fitting 21, the caulking fitting 22, and the tongue pipe 23 are integrally formed. A lap belt anchor plate 8 is fitted to the root of the tongue pipe 23 so that the end 7a of the lap belt 7 made of normal webbing can be fixed.

Here, each member constituting the expansion structure 10 will be described. FIG. 1 schematically shows a process in which the gas is introduced into the tube 12 through the gas circulation hole 24 as shown by an arrow A in the figure and expands from a normal flat belt shape to a spindle shape. A tubular bag filter 11 for trapping a carbon powder or other burnt residue (residue) ejected together with the high-temperature reaction gas is housed in the tube 12. The end of the bag filter 11 is fixed to the outer peripheral surface of the end fitting 21 by caulking. This bag filter 11
Uses a cloth filter that is capable of capturing high-temperature fine debris and that is fine enough to allow gas to pass freely. Since high-temperature cinders adhere to the inner surface of the filter, it is preferable to use heat-resistant cloth as the material of the filter.

The tube 1 is composed of a thin film structure made of silicone rubber, the root part is fixed to the end fitting 21, and the tip part 12a is kept airtight by the adhesive joint belt 16 connected to the webbing 15. The outer surface is partially turned upside down and bonded so that the outer surface becomes the bonding surface.

Further, the tube 12 is housed in a tubular knitted fabric 13 knitted into a slightly larger size. This knitted fabric 13 is composed of a circular knitted fabric using polyester yarn, and the knitted fabric 13 of the circular knitted fabric is difficult to stretch in the longitudinal direction of the belt (the warp direction of the knitted fabric: the warp direction) and has a cylindrical shape. It has a property of being easily stretched in a direction in which the circumference becomes large (the weft direction of the knitted fabric: the weft direction), and the weft direction can expand in accordance with the expansion deformation of the tube 12, and as shown in the figure, it adheres to the outer surface of the tube 12. As you can see, the stitches are widened and deformed.

Further, a cloth cover 14 is attached so as to cover the entire tubular knitted cloth 13. The cloth cover 14 is formed by sewing a knitted cloth material (tricot or the like) having a predetermined size into an elongated tubular shape. In the present embodiment, the entire length of the seam allowance portion of the expansion structure 10 is thin thread (60d). It is sewn once, and the both end regions are sewn twice using a thick thread (630d) at a finer pitch than the fine thread portion. As described above, since the stitching portion in the central portion is sewn only with the thin thread, when the tube 12 expands, the thin thread is cut and the seam is dissociated. The knitted fabric 13 expands so as to protrude from this portion.

At this time, the terminal treatment of the tip portion 10b of the expansion structure 10 will be described with reference to FIG. In the figure, an adhesive joint belt 16 is connected to the end of the webbing with a predetermined lap length. The joint belt 16 for adhesion is made of a plain weave fabric having a width slightly smaller than that of the ordinary webbing 15. As shown in the drawing, the end portion of the knitted fabric 13 and the end portion of the cover 14 are adhered to the webbing 15 by a sewing thread of synthetic fiber. It is firmly sewn at the joining position of the joint belt 16. Further, the tube 12 is adhered to the tip of the adhesive joint belt 16 such that the tip of the tube 12 comes very close to the stitched portion 17 of the knitted fabric 13 with the outer surface as the adhesive surface. In this embodiment, the distance between the tip 12a of the tube 12 and the sewn end of the knitted fabric 13 is set to about 5 mm, but the smaller the distance, the better. When the tube 12 expands in this way, the tube tip 12a is adhered to the inner surface of the knitted cloth 13 in the fixing portion so that the tube 12 locally expands rapidly in consideration of the deformation of the knitted cloth 13. You can regulate what you do. It is also possible to directly connect the expansion structure 10 to the end portion of the webbing 15 without using the adhesive joint belt 16.

FIG. 3 shows a modification of the terminal treatment of the tip of the expansion structure 10. In this modification, the cover 14 is omitted, but the cover 14 may have its ends fixed together at the time of die sewing, or may be sewn to another position of the webbing 15. FIG. 6A is a partial cross-sectional view showing a state where the processing of the end portion is completed. As shown in the figure, the tube 12 is adhered to the outer surface of the webbing type sewn portion 17 so that the outer surface becomes the adhesive portion 18. (B) of the same figure
FIG. 6D is an explanatory diagram shown for explaining the procedure for forming the terminal processing unit of FIG. FIG. 2B shows a state in which the knitted fabric 13 in which the front and back sides are turned upside down is covered on the ends of the webbing, and the ends thereof are sewn.
From this state, it is preferable that the tube 12 is further covered as shown in FIG. 3C or FIG. 3D, and a slightly thick adhesive is applied so that the irregularities of the die-stitched portion 17 do not appear on the tube surface. FIG. 3D shows an example in which the adhesive portion 18 is configured so that the tip end portion of the tube 12 completely covers the sewn portion 17. With this adhesive shape, airtightness can be further maintained. In this manner, the ends of the inflatable structure 10 are laminated so that the ends are "bag stitched" and the front and back are turned upside down to obtain the state shown in FIG. By adopting the “bag stitch” shape in this manner, when the tube 12 expands, the outer surface of the tube 12 comes into close contact with the inner surface of the knitted fabric 13 and the knitted fabric 13 can be expanded and expanded.

FIG. 4 is a longitudinal sectional view showing an embodiment of the invention in which a clamp is used to bring the tube 12 and the knitted cloth 13 into close contact with each other. The clamp 30 used here is shown in FIG.
The total length as shown in (a) is slightly longer than the width of the expansion structure 10, and the slit 31 into which the laminated portion of the tube 12 and the knitted fabric 13 can be fitted is formed at the center position thereof.
As shown in FIG. 4A, the tube 12 is inserted into the slit 31.
The knitted fabric 13 and the knitted fabric 13 are sandwiched with the joint belt 16 for bonding as a core to bond the respective parts. At this time, the end surface of the slit 31 into which the tube 12 and the knitted fabric 13 are inserted is finished so as to form a convex curved surface. As a result, as shown in FIG. 4B, when the expansion structure 10 expands, the surface of the knitted fabric 13 is pressed along the convex curved surface, so that a smooth expanded shape can be obtained when expanded. Thereby, the tube 12 and the knitted fabric 13 can be intimately contacted and expanded. The clamp 30 is preferably a metal or resin molded product designed to have a cross-sectional shape that is resistant to deformation and has high bending rigidity. As another modified example of the clamp 30, a type in which a hinge is formed at one end as shown in FIG. 5B, or a lightweight metal plate processed product in which a pressing surface is formed by press working is possible. Although the clamp 30 is housed in the cover, it is preferable that the clamp 30 is thin from the viewpoint of touch, as long as the rigidity is ensured.

FIG. 6 shows a modified example in which the tube 12 and the knitted fabric 13 are sandwiched by using the clamp 30 and an end treatment is applied by "bag sewing". As shown in FIG. 6C, the inside of the webbing is covered with the inside-out knitted fabric 13 to bond the webbing and the knitted fabric 13, and the tip of the inside-out tube 12 is bonded to the bonded portion. . As shown in FIG. 3D, the tip portion may be formed with an adhesive portion 18 so as to extend the tube 12 so as to cover the knitted cloth 13 and the webbing end surface with an adhesive in order to enhance the airtightness and to bond them to each other. . Thereafter, the stacked webbing ends are clamped 30 as shown in FIG.
Sandwich with. In this state, the knitted fabric 13 may be turned upside down so that the expansion structure 10 is shaped. In this modification, since the webbing end portion is securely clamped by the clamp 30, there is an advantage that the die-sewn portion can be omitted. However, it goes without saying that the strength may be increased by die-stitching if necessary in consideration of the adhesive strength.

An embodiment in which the die-sewing pattern is changed to have sufficient strength in the pulling direction of the webbing and to suppress deformation of the die-sewn portion in the expanding direction when the tube is expanded is shown in FIGS. 7 and 8. Will be described with reference to.
Usually, the pattern sewing is sewn in the pattern sewing pattern as shown in FIG. 7A in consideration of the tensile resistance between the knitted fabric 13 and the webbing 15 (see FIG. 8A). However, with this pattern and the strength of the yarn used, the tube 12 and the knitted fabric 13 are
As shown in (b), the sewn portion is expanded due to the acting internal pressure when expanded, and the knitted fabric 13 is greatly deformed, so that a gap is formed between the tube 12 and the knitted fabric 13. Therefore,
The pattern was sewn as shown in FIG. 7B, and the tensile strength of the yarn used was also high. As a result, sufficient deformation resistance is exhibited against the tensile force acting as shown by the arrow in FIG. Therefore, the tube 12 can be expanded without being broken even if the tip of the tube 12 is closed.

FIG. 9 shows an example in which a resin cover is used as a modification of the cloth cover 14. FIGS. 3A and 3C show the expansion structure 10 which is held in a belt shape at the time of normal mounting, and a vinyl chloride resin (PVC) cover 14 is mounted on the outer surface thereof. A linear perforation 14a is formed on the surface of the cover 14 shown in FIG. 7A, and when the gas is introduced from the gas generator as shown in FIG. 14
The a is torn and the knitted fabric 13 contained in the cover 14 expands so as to protrude from the crevice, and both ends of the cover 14 only expand in a substantially cylindrical shape, and the expansion structure 10 expands in a substantially spindle shape as a whole. be able to. In the same figure (c), perforations 14a are formed in a spiral shape in the longitudinal direction, and other perforations 14b are formed in a ring shape near both ends of the perforations 14a so as to intersect the perforations 14a.
A modified example is shown in which a part 14c of the cover 14 is detached at the same time when gas is introduced, and the cover 14 is left only at both ends. Perforation 1 in the longitudinal direction as shown in FIG.
Since the end of 4a is extended to the outside of the ring-shaped perforation 14b, the expanded knitted fabric 1 as shown in FIG.
The end portion of 3 can be connected to the tubular portion while maintaining a smooth shape.

In this modification, the same effect can be obtained by forming a linear weak portion having a thin resin wall instead of the perforations and tearing this portion. Further, as the material of the cover, various synthetic resin products having flexibility can be applied in addition to PVC.

[0033]

As is apparent from the above description, according to the present invention, it is possible to surely operate the inflating structure that expands rapidly, and to further improve the operation accuracy of the seat belt device. Has the effect.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of an expansion structure according to the first invention.

FIG. 2 is a partially enlarged cross-sectional view showing a cylinder tip portion of the expansion structure shown in FIG. 1 in an enlarged manner.

FIG. 3 is a partial cross-sectional view showing a modified example of the terminal processing of the tube end portion shown in FIG.

FIG. 4 is a partial cross-sectional view showing an embodiment of a terminal treatment of the expansion structure according to the second invention.

5 is a schematic perspective view showing an example of the clamp shown in FIG.

6 is a partial cross-sectional view showing a modified example of the terminal treatment of the tip portion of the cylinder shown in FIG.

FIG. 7 is a partial view of the die-stitched portion showing an example of the pattern of the die-stitched portion in the end processing of the expansion structure.

FIG. 8 is a partial cross-sectional view schematically showing the direction of the tensile force acting on the die-stitched portion.

FIG. 9 is an explanatory view showing a modified example of the cover of the expansion structure.

FIG. 10 is a state explanatory view schematically showing an example of a mounted state of a seat belt device incorporating a conventional inflatable structure.

FIG. 11 is an operation explanatory view schematically explaining the expansion operation of the conventional expansion structure.

[Explanation of symbols]

 10 Expansion structure 11 Bag filter 12 Tube 13 Knitted cloth 14 Cover 15 Webbing 30 Clamp

Claims (4)

[Claims] 1. A tubular expansive body that is inflatable while being kept airtight by an introduced gas from a gas generating means connected to an opening end, and the tubular expansive body is housed inside.
In an expansion structure of a seatbelt device in which a bag-shaped portion capable of expanding and deploying in a substantially spindle shape following the expansion deformation of the tubular expansion body is connected to an end portion of a webbing, the tubular expansion body has a tip. A joint portion of the closing portion to the webbing is provided sufficiently close to a joint portion of the bag-shaped portion with the end portion of the webbing so that the outer surface of the tip closing portion closely adheres to the inner surface of the bag-shaped portion. An inflatable structure for a seat belt device, which is inflatable. 2. A tubular expansive body which is inflatable while being kept airtight by an introduced gas from a gas generating means connected to an opening end, and the tubular expansive body is housed therein.
In an expansion structure of a seatbelt device in which a bag-shaped portion capable of expanding and deploying in a substantially spindle shape following the expansion deformation of the tubular expansion body is connected to an end portion of a webbing, the tubular expansion body has a tip. A joint portion of the closing portion to the webbing is provided by laminating with a joint portion of the bag-shaped portion with the end portion of the webbing, and the outer surface of the tip closing portion is expanded so as to be in close contact with the inner surface of the bag-shaped portion. An inflatable structure for a seat belt device, comprising: 3. A clamped portion is clamped in a laminated state between a joint portion of a tip closed portion of the tubular expander to the webbing and a joint portion of an end portion of the webbing of the bag portion. The inflatable structure for a seat belt device according to claim 2, wherein: 4. The bag-shaped portion is covered with a cover having a linear weak portion formed on the surface thereof, and the linear weak portion is broken by the action internal pressure and expands and deploys in a substantially spindle shape. An inflatable structure for a seat belt device according to claim 1 or 2.