JP2001058558A - Airbag of head-protection airbag device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate necessary and sufficient tension between a swelling part for the front seat and a swelling part for the rear seat fitted at the front and the back intervened by a central non-swelling part of an airbag of a head protection airbag equipment, and then to surely inhibit the moving of each swelling part toward outside of a vehicle at the time of restraint of the crew. SOLUTION: In front and back of an intervening central non-swelling part 11a, a swelling part for the front seat 11b and a swelling part for the rear seat 11c are provided, and this is an airbag 11 of a head-protection airbag device that swells and expands in a curtain shape at the side parts of the cabin, and it is so constructed that a part of a belt 15 that is assembled to the airbag 11 with both ends fixed is latched against a lower peripheral part of the central non-swelling part 11a in a relatively movable condition, and a tension is generated on the belt 15 due to swelling transformation from at least one-side of both swelling parts 11b, 11c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airbag for a head protection airbag device mounted on a vehicle.

[0002]

2. Description of the Related Art An airbag of a head protection airbag device is inflated and deployed in a curtain shape at a side portion of a vehicle interior. One of the airbags is a front seat inflatable portion and a rear seat inflatable portion. Some are provided, for example, in WO96 / 26087. In the airbag disclosed in the publication, a plurality of inflation chambers extending in a vertical direction by a plurality of non-inflation portions are arranged in the front-rear direction, a front portion thereof is a front seat inflation portion, and a rear portion thereof is provided. The part is a rear seat inflatable part.

[0003]

In the airbag disclosed in the above-mentioned publication, a plurality of inflation chambers extending in the vertical direction are provided at a central portion between the inflation portion for the front seat and the inflation portion for the rear seat. Therefore, if each expansion chamber expands and deforms, the distance between each non-expansion part is narrowed, tension is generated in both expansion parts in the front-rear direction, and the movement of each expansion part to the outside of the vehicle when the occupant is restrained is suppressed. However, it is necessary to supply gas also to the expansion chamber at the central portion, and it is necessary to supply a large amount of gas in a short time.

On the other hand, if a non-inflating portion is provided in a wide area at the center between the inflating portion for the front seat and the inflating portion for the rear seat in the airbag, the amount of gas supplied to the airbag can be reduced. Insufficient tension occurs at the central non-inflation portion between the front seat expansion portion and the rear seat expansion portion, and the tension is not properly transmitted between the two expansion portions, and the movement of each expansion portion to the outside of the vehicle when the occupant is restrained is accurately performed. There is a possibility that it cannot be suppressed.

[0005]

SUMMARY OF THE INVENTION The present invention addresses the above-mentioned problem (problem in a case where a non-inflating portion is provided over a wide area at a central portion between an inflating portion for a front seat and an inflating portion for a rear seat in an airbag). The head protection airbag has a front seat inflation portion and a rear seat inflation portion in front of and behind the central non-inflation portion, and is inflated and deployed in a curtain shape on the side in the vehicle cabin. An airbag of the device, wherein a part of a belt fixed to both ends of the airbag and fixed to the airbag is movably engaged with a lower edge of the central non-inflatable portion, and the both inflatable portions are The invention is characterized in that a tension is generated in the belt by at least one of the expansion deformations (the invention according to claim 1).

In this case, the belt is fixed at one end to a non-inflation portion above the front-seat expansion portion or the rear-seat expansion portion, and has an intermediate portion at the front-seat expansion portion or the rear-seat expansion portion. Movably inserted into a through-hole provided in a non-expandable portion below the inflatable portion, and the other end is fixed to a lower edge portion of the central non-expandable portion, and the front seat is located between one end and an intermediate portion. The belt extends along the outer peripheral surface of the inflatable portion for the rear seat or the inflatable portion for the rear seat, and tension is generated in the belt by expansion deformation of the inflatable portion for the front seat or the inflatable portion for the rear seat. (The invention according to claim 2) is also possible.

The belt is fixed at one end to a non-expandable portion above the front seat inflatable portion, and is fixed at the other end to a non-expandable portion above the rear seat inflatable portion. A through-hole provided in a non-inflated portion below the front seat inflatable portion, a through-hole provided in a non-inflated portion below the rear seat inflatable portion, and a lower edge of the central non-inflated portion. Respectively, movably inserted into the through holes provided in the rear seat, extending along the outer peripheral surface of the front seat inflatable portion from one end to the intermediate portion, and extending from the other end to the intermediate portion. The belt extends along the outer peripheral surface of the inflatable portion, and the tension is generated in the belt by the expansion deformation of the inflatable portion for the front seat and the inflatable portion for the rear seat. Such an invention) is also possible.

The belt is disposed in the central non-expandable portion, the intermediate portion is movably inserted into a through hole provided in a lower edge portion of the central non-expandable portion, and at least one of both ends is inserted. The length of the airbag from the through hole to the one end fixed portion in the airbag deployed state, and the length of the airbag from the through hole to the other end fixed portion fixed to the central non-inflating portion at a position above the insertion portion. The belt length is set to be shorter in advance than the sum of the lengths of the belts, and the central non-expandable portion expands in the vertical direction due to the expansion deformation of the front-seat expansion portion and the rear-seat expansion portion. (The invention according to claim 4) is also possible.

[0009]

In the airbag according to the present invention (the invention according to claim 1), when the airbag is inflated and deployed in a curtain shape, a part of the airbag relatively moves with respect to the lower edge of the central non-inflated portion. Tension is generated by the expansion deformation of at least one of the front seat inflatable portion and the rear seat inflatable portion in the belt that can be engaged, and this tension is transmitted from a part of the belt to the lower edge portion of the central non-inflatable portion, The inflatable portion for the front seat and the inflatable portion for the rear seat of the airbag are pulled in directions approaching each other. Therefore, a necessary and sufficient tension is generated between the front seat inflation portion and the rear seat inflation portion of the airbag, and the movement of each inflation portion to the outside of the vehicle when the occupant is restrained can be accurately suppressed.

Further, in the airbag according to the present invention (the invention according to claim 2), when the airbag is inflated and deployed in a curtain shape, a portion between one end (fixed portion) of the belt and the intermediate portion is inflated for the front seat. The belt is pushed by the inflation and deformation of the inflatable portion or the rear seat inflatable portion, and tension is generated in the belt, and this tension is transmitted from the other end (fixed portion) of the belt to the lower edge of the central non-inflated portion, and the front of the airbag is The inflatable portion for the seat and the inflatable portion for the rear seat are pulled in a direction approaching each other. Therefore, a necessary and sufficient tension is generated between the front seat inflation portion and the rear seat inflation portion of the airbag, and the movement of each inflation portion to the outside of the vehicle when the occupant is restrained can be accurately suppressed.

Further, in the airbag according to the present invention (the invention according to claim 3), when the airbag is inflated and deployed in a curtain shape, a portion between one end (fixed portion) and the intermediate portion of the belt is inflated for the front seat. The belt is pushed by the expansion deformation of the belt portion, and a portion between the other end (fixed portion) of the belt and the intermediate portion is pushed by the expansion deformation of the rear seat expansion portion, thereby generating a large tension on the belt. As a result, the front-seat inflatable portion and the rear-seat inflatable portion of the airbag are pulled toward each other at the intermediate portion of the belt. Therefore, a necessary and sufficient and large tension is generated between the front seat inflation portion and the rear seat inflation portion of the airbag, and the movement of each inflation portion to the outside of the vehicle when the occupant is restrained can be accurately suppressed.

Further, in the airbag according to the present invention (the invention according to claim 4), when the airbag is inflated and deployed in the shape of a curtain, the central non-inflatable portion is inflated by the inflatable portions for the front seat and the rear seat. The belt expands in the vertical direction and tension is generated in the belt, and this tension is transmitted from the middle of the belt to the lower edge of the central non-inflated portion, and the inflatable portion for the front seat and the inflatable portion for the rear seat of the airbag are separated. They are pulled in directions that approach each other. Therefore, a necessary and sufficient tension is generated between the front seat inflation portion and the rear seat inflation portion of the airbag, and the movement of each inflation portion to the outside of the vehicle when the occupant is restrained can be accurately suppressed.
Further, in the present invention, since the belt is disposed in the central non-inflation portion, the inflation portion for the front seat and the inflation portion for the rear seat can be freely designed without being restricted in shape by the belt. It is.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show the first embodiment of the present invention.
Embodiment 1 is shown, and in this first embodiment,
An airbag 11 for protecting a head Hf of a front seat occupant and a head Hr of a rear seat occupant by inflating and deploying a head protection airbag device 10 in a curtain shape at a side portion in a vehicle cabin; A gas supply pipe 12 for supplying gas to the airbag 11, an inflator 13, a front tension belt 14 for tensioning the entire airbag 11, a central tension belt 15 for tensioning the central non-inflating portion 11a of the airbag 11, and the like. ing.

The airbag 11 has a front seat inflatable portion 11b and a rear seat inflatable portion 11c in front of and behind the central non-inflating portion 11a.
And has a plurality of mounting pieces 11d at the upper edge thereof. Each mounting piece 11d is assembled to the roof side rail 21 by using a fixing tool (not shown) such as a bolt, and is folded. It is housed along the roof side rail 21 in the roof state and the roof head garnish (not shown)
Is covered by the peripheral portion of the cover.

The airbag 11 is provided with a gas supply pipe 12.
A gas introduction passage Pa extending obliquely downward toward the front having an opening connected to the front end portion at the rear end upper portion, and an upper front seat extending rearward communicating with the front end of the gas introduction passage Pa. The front expansion chamber Pb communicates with the front end of the gas introduction passage Pa and the front of the middle part, and extends downward in the front-rear direction. The lower front expansion chamber Pc communicates with the middle part of the gas introduction passage Pa and extends rearward. It has a pair of rear-seat expansion chambers Pd and Pe, and a front part of the gas introduction path Pa and a pair of upper and lower front-seat expansion chambers Pb and Pc constitute a front-seat expansion section 11b. And a pair of upper and lower rear-seat expansion chambers Pd and Pe constitute a rear-seat expansion portion 11c. An inflation chamber Pf for improving the deployment of the airbag 11 is continuously formed in front of the front seat inflation chamber Pb.

The gas supply pipe 12 is attached to the tip of the inflator 13 and is covered with a quarter pillar garnish (not shown). The inflator 13 blows out gas at the time of a side collision of the vehicle, and is disposed along the quarter pillar 22.
Attached to the quarter pillar 22 via the bracket 13a, the quarter pillar garnish (not shown)
To be covered by

The front tension belt 14 is made of a material that is easy to fold and is difficult to extend. One end 14a is fixed to a non-inflated portion in the upper front part of the airbag 11 by sewing, and the middle part is a lower front part of the airbag 11. The other end 14b is movably inserted into a through hole (slit) 11e provided in the non-expandable portion of the above, and the other end 14b is fixed to a lower portion of the front pillar 23 using a fixing tool such as a bolt (not shown). The airbag 11 extends along the front edge of the front seat inflatable portion 11b between the intermediate portions, and generates a predetermined tension F1 by inflation deformation of the front seat inflatable portion 11b (the airbag 11 is shown in FIG. 1). As shown in (2), the belt length is set so that a predetermined tension F1 is generated when the belt is inflated and deployed. In addition, the tension belt 14 is used for the airbag 1.
When it is stored along the roof side rail 21 in a folded state, it is stored along the front pillar 23 and a front pillar garnish (not shown)
To be covered by

The center tension belt 15 is made of a material that is easy to fold and is difficult to extend. One end 15a is fixed to a non-expandable portion above the front-seat inflatable portion 11b by sewing, and an intermediate portion is used for the front-seat. Through-holes (slits) 11 provided in two non-expandable portions at the intermediate portion of the expanded portion 11b
f, 11g and through holes (slits) 11h provided in the lower non-expandable portion are sequentially movably inserted, and the other end 15b is fixed to the lower edge of the central non-expandable portion 11a by sewing. Along the outer peripheral surface of the front seat expansion portion 11b from the center portion 15a to the intermediate portion (specifically, the outside of the upper expansion chamber Pb, the inside of the gas introduction path Pa, and the lower expansion chamber Pc).
(Extends along the outside of the vehicle compartment), and a predetermined tension F2 is generated by the expansion and deformation of the front seat expansion portion 11b (when the predetermined tension F2 is expanded and expanded when the front seat expansion portion 11b is expanded and expanded). The belt length is set so that it occurs).

In the first embodiment configured as described above, a gas is blown out of the inflator 13 at the time of a side collision of the vehicle or the like, and the gas is supplied into the airbag 11 through the gas supply pipe 12 so that the airbag 11 When the airbag 11 is inflated and deployed in a curtain shape as shown in FIG. 1, a tension F1 is generated in the tension belt 14, and the airbag 11 is pulled obliquely forward at a lower front portion thereof, and one end of the tension belt 15 (a fixing portion). ) A portion between 15a and the intermediate portion is pushed by the inflation deformation of the front seat inflatable portion 11b of the airbag 11 to generate a tension F2 on the tension belt 15, and this tension F2 is applied to the other end of the tension belt 15 (fixed portion). ) 15b to the lower edge of the central non-inflatable portion 11a of the airbag 11 so that the front seat inflatable portion 11
b and the rear inflatable portion 11c are pulled in a direction in which they approach each other. Accordingly, a necessary and sufficient tension is generated in the lower front part of the airbag 11, and a necessary and sufficient tension is generated between the front seat inflatable portion 11b and the rear seat inflatable portion 11c of the airbag 11, so that each of the airbags 11 is restrained during occupant restraint. The movement of the expansion portions 11b and 11c to the outside of the vehicle can be accurately suppressed.

In the first embodiment, the tension belt 15 is provided at the position shown in FIGS. 1 and 2 so that a predetermined tension F2 is generated on the tension belt 15 by the expansion deformation of the front seat expansion portion 11b. However, as in the second embodiment shown in FIG.
4 can be provided at the position shown in the figure, so that a predetermined tension F2 is generated on the tension belt 15 by the expansion and deformation of the rear-seat expansion portion 11c.
As shown in the third embodiment, the tension belt 15 is provided at the illustrated position so that the predetermined tension F2 is generated on the tension belt 15 by the expansion deformation of the front seat expansion portion 11b and the rear seat expansion portion 11c. It is also possible to configure and implement.

The tension belt 15 of the second embodiment shown in FIG. 3 is made of a material that is easy to fold and does not easily extend, and has one end 15a fixed to a non-expandable portion above the rear inflatable portion 11c by sewing. The through holes (slits) 11f and 11g provided in the non-expandable portions at two intermediate portions of the rear seat inflatable portion 11b and the through holes (slits) 11h provided in the lower non-inflatable portion are provided. The other end 15b is fixed to the lower edge of the central non-expandable portion 11a by sewing, and extends along the outer peripheral surface of the rear seat inflatable portion 11c from one end 15a to the intermediate portion. Location (in detail,
(Extends along the outside of the cabin of the gas introduction path Pa, the inside of the upper inflation chamber Pd, and the outside of the lower inflation chamber Pe), and a predetermined tension F2 is generated by the inflation deformation of the rear seat inflation portion 11c. (The belt length is set so that a predetermined tension F2 is generated when the rear seat inflatable portion 11c is expanded and inflated)
Have been.

The tension belt 15 of the third embodiment shown in FIG. 4 is made of a material that is easy to fold and hard to extend, and has one end 15a fixed to a non-expandable portion above the front inflatable portion 11b by sewing. The other end 15b is fixed to the non-expandable portion above the rear-seat inflatable portion 11c by sewing, and the intermediate portion is provided in each of the two non-expandable portions at the intermediate portion of the front-seat inflatable portion 11b. (Slit) 11f, 1
1g and the through hole (slit) 1 provided in the lower non-expandable part
1h, a through-hole (slit) 11i provided at the center of the lower edge portion of the central non-expandable portion 11a, a through-hole (slit) 11j provided at a non-expandable portion below the rear inflatable portion 11c, and two intermediate portions. Through holes (slits) 1 provided in each non-expandable part
1k and 11m are inserted so as to be movable sequentially,
5a extending along the outer peripheral surface of the front seat expansion portion 11b between the middle portion and the middle portion (specifically, the vehicle outside the vehicle interior of the upper expansion chamber Pb, the vehicle interior side of the gas introduction path Pa, and the vehicle of the lower expansion chamber Pc). (Extends along the outside of the vehicle) and extends along the outer peripheral surface of the rear-seat inflatable portion 11c from the other end 15b to the intermediate portion (specifically, the interior side of the gas introduction passage Pa and the upper inflation chamber). Pd extends along the outside of the passenger compartment and along the inside of the lower inflation chamber Pe.
b and a predetermined tension F2 is generated by the expansion deformation of the rear seat expansion portion 11c (the predetermined tension F2 is generated when the front seat expansion portion 11b and the rear seat expansion portion 11c are deployed and expanded). Belt length is set).

In each of the above embodiments, a part of the tension belt 15 fixed to both ends of the airbag 11 can be relatively moved with respect to the lower edge of the central non-inflated portion 11a of the airbag 11. , The tension is generated in the tension belt 15 by the inflation deformation of at least one of the two inflatable portions 11b and 11c in the airbag 11. However, in the fourth embodiment shown in FIG. As shown in the fifth embodiment shown in FIG. 7 or the sixth embodiment shown in FIG. 7, the tension belts 15 are respectively provided at the illustrated positions, and the inflation deformation of the front seat inflation portion 11b and the rear seat inflation portion 11c of the airbag 11 is performed. Thus, the central non-expandable portion 11a may be configured to be developed in the vertical direction to generate a predetermined tension F2 on the tension belt 15, and may be implemented.

The tension belt 15 of the fourth embodiment shown in FIG. 5 is made of a material that is easy to fold and hard to extend, is disposed in the central non-inflating portion 11a of the airbag 11, and has It is movably inserted into a pair of through holes 11n and 11p provided in the lower edge of the inflatable portion 11a, and both ends 15a and 15b are connected to the central non-inflatable portion 11a of the airbag 11 at positions above the insert portion. It is fixed. The length L1 of the tension belt 15 from the through hole 11n to the one end fixing portion (15a) in the deployed state of the air bag, and the air bag from the through hole 11n to the other end fixing portion (15b) through the through hole 11p. Length L in expanded state
2 (Length from through hole 11n to through hole 11p and through hole 11p
The length of the belt L is set to be shorter in advance than the sum of the length of the front bag and the other end fixing portion (15b). The central non-expandable portion 11a expands in the vertical direction due to the expansion and deformation of the portion 11c, and a predetermined tension is generated in the tension belt 15.

The tension belt 15 of the fifth embodiment shown in FIG. 6 is made of a material that is easy to fold and does not easily extend, is disposed in the central non-inflating portion 11a of the airbag 11, and has One end 15 is movably inserted into a through hole 11 r provided in a lower edge portion of the expansion portion 11 a.
a is fixed to the central non-inflated portion 11a of the airbag 11 at a position above the insertion portion, and the other end 15b is positioned at the same level as the through hole 11r.
a. Also, the tension belt 15
The length L1 of the airbag from the through hole 11r to the one end fixing portion (15a) in the deployed state, and the length L1 from the through hole 11r to the other end fixing portion (1a).
The belt length L is set to be shorter in advance than the sum of the length L2 in the deployed state of the airbag up to 5b), and the front-seat inflatable portion 11b and the rear-seat inflatable portion 11c of the airbag 11 are provided. The central non-expandable portion 11a expands in the vertical direction due to the expansion and deformation of the tension belt 15, and a predetermined tension is generated in the tension belt 15.

The tension belt 15 according to the sixth embodiment shown in FIG. 7 is made of a material that is easy to fold and is difficult to extend. Through hole 1 provided in lower edge of portion 11
1t so as to be movable, and both ends 15a, 1
5b is fixed to the central non-inflating portion 11a of the airbag 11 at a position above the insertion portion. The length L1 of the tension belt 15 from the through hole 11t to the one end fixing portion (15a) in the deployed state of the airbag and the length from the through hole 11t to the other end fixed portion (15b) in the deployed state of the air bag. The belt length L is set to be shorter in advance than the sum of L2 and the front inflatable portion 11 in the airbag 11.
The central non-expandable portion 11a expands in the vertical direction due to the expansion and deformation of the inflatable portion 11b and the rear seat inflatable portion 11c, so that a predetermined tension is generated in the tension belt 15.

In each of the embodiments shown in FIGS. 5 to 7, when the airbag 11 is inflated and deployed in a curtain shape, the central non-inflated portion 11a is inflated by the inflation deformation of the front seat inflatable portion 11b and the rear seat inflatable portion 11c. Is developed in the vertical direction, and tension is generated in the tension belt 15, and this tension is transmitted from the middle portion of the tension belt 15 to the lower edge of the central non-inflation portion 11 a, and the front seat inflation portion 11 b of the airbag 11 and The rear seat inflatable portions 11c are pulled in directions approaching each other. Therefore, similarly to the embodiments shown in FIGS. 1 to 4, necessary and sufficient tension is generated between the front seat inflatable portion 11b and the rear seat inflatable portion 11c of the airbag 11, and each inflatable portion is restrained when the occupant is restrained. The movement of 11b, 11c to the outside of the vehicle can be accurately suppressed. In each of these embodiments,
Since the tension belt 15 is disposed at the central non-inflation portion 11a of the airbag 11, the front seat inflation portion 11b and the rear seat inflation portion 11c can be freely designed without being restricted by the tension belt 15. It is possible to

In each of the above embodiments, the airbag 1
A tension belt 14 is provided in the lower front part of the first airbag 1, and the airbag 11 is pulled obliquely forward in the lower front part by the tension F1 generated in the tension belt 14, but the seventh embodiment shown in FIG. A semi-ring shaped inflation chamber Pg is provided at the front end of the airbag 11 as described above, and tension is applied to a front portion of the airbag 11 by tension generated by inflation deformation of the inflation chamber Pg. It is also possible.

Further, in each of the above embodiments, the present invention is applied to the head protection airbag device for supplying gas to the airbag 11 from the rear, but the head protection airbag for supplying gas to the airbag 11 from the front is provided. The present invention can be similarly applied to a bag device (for example, a device disclosed in JP-A-11-91489).

[Brief description of the drawings]

FIG. 1 is a side view showing a first embodiment of the present invention.

FIG. 2 is a side view showing a state in which the airbag and both tension belts shown in FIG. 1 are deployed.

FIG. 3 is a diagram corresponding to FIG. 2, showing a second embodiment of the present invention.

FIG. 4 is a diagram corresponding to FIG. 2, showing a third embodiment of the present invention.

FIG. 5 is a view corresponding to FIG. 2 showing a fourth embodiment of the present invention.

FIG. 6 is a diagram corresponding to FIG. 2, showing a fifth embodiment of the present invention.

FIG. 7 is a diagram corresponding to FIG. 2, showing a sixth embodiment of the present invention.

FIG. 8 is a diagram corresponding to FIG. 2, showing a seventh embodiment of the present invention.

[Explanation of symbols]

10 ... Head protection airbag device, 11 ... Airbag, 1
1a: central non-expandable portion; 11b: front-seat inflatable portion;
Rear seat inflatable portion, 11d mounting pieces, 11e, 11f, 11
g, 11h, 11i, 11j, 11k, 11m, 11
n, 11p, 11r, 11t ... through-hole (slit), 12
... gas supply pipe, 13 ... inflator, 14 ... front tension belt, 15 ... central tension belt, 15a
... one end of the center tension belt, 15b ... the other end of the center tension belt, Pa ... gas introduction path, Pb, Pc,
Pd, Pe, Pf, Pg ... expansion chambers.

Claims (4)

[Claims] 1. A head protection airbag device comprising: a front seat inflatable portion and a rear seat inflatable portion in front and back of a central non-inflated portion, and inflates and deploys in a curtain shape at a side portion in a vehicle cabin. At least one of the two inflatable portions, wherein a part of a belt fixed to both ends of the airbag and fixedly attached to the airbag is movably engaged with a lower edge portion of the central non-inflatable portion. An airbag for a head protection airbag device, wherein tension is generated in the belt by expansion deformation of the airbag. 2. The belt is fixed at one end to a non-inflation portion above the front-seat expansion portion or the rear-seat expansion portion, and has an intermediate portion at the front-seat expansion portion or the rear-seat expansion portion. Movably inserted into a through-hole provided in a non-expandable section below the section, the other end is fixed to the lower edge of the central non-expandable section, and the front seat inflation extends from one end to an intermediate section. And extending along the outer peripheral surface of the portion or the rear seat inflatable portion, wherein the belt is configured to generate tension by expansion deformation of the front seat inflatable portion or the rear seat inflatable portion. The airbag of the head protection airbag device according to claim 1. 3. The belt is fixed at one end to a non-expandable portion above the front seat inflatable portion, and is fixed at the other end to a non-expandable portion above the rear seat inflatable portion. A through-hole provided in a non-inflated portion below the front seat inflatable portion, a through-hole provided in a non-inflated portion below the rear seat inflatable portion, and a lower edge of the central non-inflated portion. Respectively, movably inserted into the through holes provided in the rear seat, extending along the outer peripheral surface of the front seat inflatable portion from one end to the intermediate portion, and extending from the other end to the intermediate portion. The belt extends along the outer peripheral surface of the inflatable portion, and tension is generated in the belt by the inflated deformation of the inflatable portion for the front seat and the inflatable portion for the rear seat. An airbag for the head protection airbag device as described in the above. 4. The belt is disposed in the central non-expandable portion, the intermediate portion is movably inserted into a through hole provided in a lower edge portion of the central non-expandable portion, and at least one of both ends is inserted. The length of the airbag from the through hole to the one end fixed portion in the airbag deployed state, and the length of the airbag from the through hole to the other end fixed portion fixed to the central non-inflating portion at a position above the insertion portion. The belt length is set to be shorter in advance than the sum of the lengths of the belts, and the central non-expandable portion expands in the vertical direction due to the expansion deformation of the front-seat expansion portion and the rear-seat expansion portion. The airbag for a head protection airbag device according to claim 1, wherein a tension is generated in the airbag.