Airbag

Abstract

To provide an airbag capable of protecting a protection object in a more stable manner with an inexpensive structure.SOLUTION: An airbag 1 includes: a first expansion part 12 in which left and right side parts are recessed toward a center part in a concave form and into which a gas is introduced; and second expansion parts 13 which are located in respective recessed portions at the left and right side parts of the first expansion part 12 and into which the gas is introduced. In expansion states of the first expansion part 12 and the second expansion part 13, the airbag 1 has a circular shape when viewed head-on.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an airbag that expands and deploys by introducing gas from a folded state.

Background Art

[0002] In a vehicle such as an automobile, an airbag that expands and deploys by introducing gas during a vehicle collision is provided with a vent hole that is an exhaust part, and when a passenger comes into contact, a part of the gas is discharged to the outside to appropriately maintain the internal pressure. For example, in the case of an airbag applied to a steering wheel of a vehicle such as an automobile, in a so-called joystick type steering wheel that does not have a rim part as a gripping part at least in the upper part, that is, on the 12 o'clock side of an analog clock, in order to stably protect the passenger, it is necessary to suppress the airbag from shifting upward to the upper part where there is no rim part that acts as a reaction plate.

[0003] Therefore, for example, in an airbag applied to a steering wheel of a vehicle such as an automobile, second expansion parts are set on both sides of a circular first expansion part that is the main body for protecting a passenger, and the second expansion part covers the side part of the first expansion part and protrudes with respect to the first expansion part. There is known an airbag having such a shape. Then, while gas is introduced into the first expansion part and the first expansion part expands and deploys at the center part of the steering wheel, the gas is introduced into the second expansion part through the first expansion part, so that the second expansion part expands and deploys so as to cover the left and right rim parts. By doing so, the second expansion part is held with respect to the left and right rim parts to suppress the upward displacement of the airbag, and at the same time, the first expansion part receives the head of the passenger to restrain the passenger, and when the first expansion part receives the passenger, a part of the gas flows into the second expansion part, thereby relaxing the reaction force from the airbag (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the case of the above shape, in order to protect the shoulders of the occupant, it is necessary to widely set the second inflation part that covers the circular first inflation part, which may lead to an increase in the size of the gas generator and the need for special folding of the airbag. Further, when the first inflation part and the second inflation part are configured so that the airbag is circular when viewed from the front, it is required to prevent the contact area of the airbag with the occupant from being reduced.

[0006] The present invention has been made in view of such points, and an object thereof is to provide an airbag that can more stably protect a protection target with an inexpensive configuration.

Means for Solving the Problems

[0007] The airbag according to claim 1 is an airbag that expands and deploys by introducing gas from a folded state, and has a first inflation part in which both left and right side portions are recessed toward the central portion and into which the gas is introduced, and a second inflation part that is respectively located in the recessed portions on both left and right side portions of the first inflation part and into which the gas is introduced through the first inflation part. In the inflated state of the first inflation part and the second inflation part, it is circular when viewed from the front.

[0008] The airbag according to claim 2 is the airbag according to claim 1, and includes a backflow prevention valve for preventing the backflow of gas from the second inflation part to the first inflation part.

[0009] The airbag according to claim 3 is the airbag according to claim 1 or 2, and the first inflation part has a protruding part protruding downward on the side opposite to the protection target in the inflated state.

[0010] The airbag according to claim 4 is the airbag according to claim 1 or 2, and the first inflation part has an exhaust part for discharging a part of the gas to the outside on the side opposite to the protection target.

[0011] The airbag according to claim 5 is the airbag according to claim 1 or 2, wherein the second inflation part does not have a discharge part for discharging gas to the outside.

Advantages of the Invention

[0012] According to the airbag described in claim 1, no special folding is required, and it can be configured at low cost. In addition, since the area in contact with the occupant can be ensured, the occupant can be protected more stably.

[0013] According to the airbag described in claim 2, in addition to the effects of the airbag described in claim 1, the holding force of the second inflation part with respect to the gripping part can be improved, and the airbag in the inflated state can be suppressed from moving upward and forward with respect to the steering wheel.

[0014] According to the airbag described in claim 3, in addition to the effects of the airbag described in claim 1 or 2, since the protruding part catches on the gripping part at the lower part of the steering wheel in the inflated state of the airbag, the airbag in the inflated state can be effectively suppressed from moving upward and forward with respect to the steering wheel.

[0015] According to the airbag described in claim 4, in addition to the effects of the airbag described in claim 1 or 2, an excessive pressure increase in the first inflation part with which the protection target mainly comes into contact can be avoided.

[0016] According to the airbag described in claim 5, in addition to the effects of the airbag described in claim 1 or 2, since the second inflation part can maintain the internal pressure even after contact with the protection target, the holding force with respect to the gripping part can be maintained, and an appropriate reaction force can be generated with respect to the protection target.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying out the Invention

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0019] In FIGS. 1(a) and 1(b), reference numeral 1 denotes an airbag. The airbag 1 of the present embodiment is exemplified as being for a driver's airbag device (DAB). This airbag device is configured such that, in addition to the airbag 1, an inflater 2, which is a gas generator that supplies gas to the airbag 1, etc. are housed in a case body, and it is mounted on a steering wheel 3, which is an attachment portion of a vehicle such as an automobile shown in FIG. 6. Then, in the event of a vehicle collision or the like, as shown in FIGS. 4(a) and 4(b), the airbag 1 expands and deploys from the case body to protect an occupant such as a driver, who is the protection target, from the impact of the collision. Note that the steering wheel 3 shown in FIG. 6 is mounted on a steering shaft, which is a steering shaft normally provided to the vehicle in an inclined state. Hereinafter, when viewing the steering wheel 3 from the occupant side, the direction of arrow U is defined as the upper side and the direction of arrow D is defined as the lower side for explanation. In addition, regarding the front-rear, left-right directions, based on the direction seen from an occupant seated in the driver's seat, in each figure, the direction of arrow FR is defined as the front side, the direction of arrow RR is defined as the rear side, the direction of arrow L is defined as the left side, and the direction of arrow R is defined as the right side. Also, regarding each part of the steering wheel 3, the position and shape are described with reference to the neutral position (neutral) shown in FIG. 6.

[0020] The steering wheel 3 has a rim portion (grip) 6, which is a gripping portion for an occupant such as a driver to grip and operate, disposed outside a boss portion 5 at the center where the airbag device is attached. The boss portion 5 and the rim portion 6 are connected by a spoke portion 7, which is a connecting portion. In the present embodiment, the rim portion 6 is set from both left and right sides to the lower portion with respect to the boss portion 5. That is, the steering wheel 3 of the present embodiment is a so-called joystick type, etc., in which the rim portion 6 does not exist at least in the upper portion, i.e., the 12 o'clock side of an analog clock. In the illustrated example, the rim portion 6 curves in an arc shape in the left and right side positions of the boss portion 5 and extends in the vertical direction, and extends linearly in the left and right direction at the lower position of the boss portion 5. Therefore, the steering wheel 3 has an overall horizontally long and vertically short, horizontally long shape.

[0021] The spoke portion 7 may be arbitrarily set as long as it can stably connect the rim portion 6 and the boss portion 5. In this embodiment, for example, it extends in the left - right direction from the left - right positions of the boss portion 5, that is, the 9 o'clock - 3 o'clock side positions of the analog clock.

[0022] And the airbag 1 shown in FIGS. 1 to 4 is formed in a bag shape having a plurality of air chambers into which gas is introduced and inflated. The airbag 1 has a first inflation portion 12 which is an air chamber (main chamber) located at the central portion in the left - right direction, and second inflation portions 13 which are air chambers (sub - chambers) located on both the left and right sides of the first inflation portion 12. The first inflation portion 12 and the second inflation portions 13 form the airbag main body portion. And, in the inflated state or the non - inflated state (not folded) of the first inflation portion 12 and the second inflation portions 13, the airbag 1 is circular when viewed from the front.

[0023] The first inflation portion 12 is located at the central portion in the left - right direction of the airbag 1 and is the main inflation portion that serves as the main body for protecting the occupant. The first inflation portion 12 extends in the up - down direction and mainly restrains and protects the portion ranging from the occupant's head to the chest and abdomen. The first inflation portion 12 is set to have a larger volume than the second inflation portions 13. For example, the first inflation portion 12 occupies more than half of the volume of the airbag 1.

[0024] Generally, the first inflation portion 12 has an outer shape whose upper and lower parts are along a virtual same circle C (shown in FIG. 2), and the left and right side portions have an outer shape that is recessed inward with respect to the virtual circle C (shown in FIG. 2). That is, recessed portions 15 are formed on both the left and right side portions of the first inflation portion 12. The recessed portions 15 have their intermediate portions in the up - down direction located closer to the central portion in the left - right direction compared to their upper and lower end portions. That is, the recessed portions 15 are recessed in a concave shape toward the central portion in the left - right direction of the first inflation portion 12 (airbag 1). In this embodiment, the recessed portions 15 are formed in the range extending from the position of the central portion in the up - down direction of the first inflation portion 12 (airbag 1) to the upper left to the lower left, that is, the range extending from 10 o'clock to 8 o'clock of the analog clock, and the range extending from the upper right to the lower right, that is, the range extending from 2 o'clock to 4 o'clock of the analog clock, respectively.

[0025] Gas is directly introduced into the first inflatable portion 12 from the inflator 2. The first inflatable portion 12 has an introduction portion 17 through which gas is introduced. The introduction portion 17 is a hole formed in a round hole shape. In the present embodiment, the gas ejection portion of the inflator 2 is inserted into the first inflatable portion 12 from the introduction portion 17. The introduction portion 17 is located at the front portion of the first inflatable portion 12 (airbag 1) on the side opposite to the occupant. In the illustrated example, the introduction portion 17 is located at the center of the front portion of the first inflatable portion 12.

[0026] Further, an exhaust portion 19 for discharging a part of the introduced gas is formed in the first inflatable portion 12. In the present embodiment, the exhaust portion 19 is an exhaust hole (vent hole) formed in a round hole shape. The exhaust portion 19 is located at the front portion of the first inflatable portion 12 (airbag 1) on the side opposite to the occupant. In the present embodiment, the exhaust portion 19 is located closer to the upper part of the front portion of the first inflatable portion 12. In the illustrated example, the exhaust portion 19 is located above the introduction portion 17 at the front portion of the first inflatable portion 12, and is arranged separately from each other on both the left and right side portions.

[0027] Preferably, a protruding portion 21 having a shape protruding to the front side opposite to the occupant A in the inflated state shown in FIG. 4(a) is formed in the first inflatable portion 12. The protruding portion 21 is a hooking structure for hooking the inflated airbag 1 so as not to shift upward with respect to the steering wheel 3. The protruding portion 21 is arranged below the first inflatable portion 12. In the present embodiment, the protruding portion 21 is formed over a position from the lower end portion of the first inflatable portion 12 to a position below the central portion in the vertical direction. The protruding portion 21 is formed to protrude in a knob shape with respect to the first inflatable portion 12. For example, the protruding portion 21 is formed by tacking a part of the lower portion of the first non-occupant side panel 24 to a joint portion (not shown).

[0028] As shown in FIGS. 1 to 3, the first inflatable portion 12 is formed by one or more panels. In the present embodiment, the first inflatable portion 12 has an outer shell formed by a pair of front and rear panels. That is, the first inflatable portion 12 includes a first occupant-side panel 23 as a first facing portion (first restraint portion) that constitutes the outer shell panel and faces the occupant, and a first non-occupant-side panel 24 as a first non-facing portion (first non-restraint portion) that does not face the occupant, that is, is located on the front side, which is the non-occupant side. The first occupant-side panel 23 and the first non-occupant-side panel 24 are joined at the position of the outer edge portion by a first joining portion 25 such as sewing to form a bag shape. These first occupant-side panel 23 and first non-occupant-side panel 24 are each made of a base fabric, for example, and are also called a base fabric, a panel, a plate, or the like. The first occupant-side panel 23 and the first non-occupant-side panel 24 may be formed of a plurality of fabrics, or a reinforcing panel such as a reinforcing fabric for reinforcement may be overlapped inside at a predetermined position, for example, at the peripheral edge portion such as the introduction portion 17 and / or the exhaust portion 19, or a coating or the like may be applied. The introduction portion 17 and the exhaust portion 19 are formed in the first non-occupant-side panel 24. Further, by sewing or the like the lower portion of the first non-occupant-side panel 24, the protruding portion 21 is configured to protrude three-dimensionally forward in an inflated state. In the present embodiment, the first occupant-side panel 23 and the first non-occupant-side panel 24 are set to have equal or substantially equal outer shapes to each other.

[0029] Further, the second inflatable portion 13 is a sub-inflatable portion located on both left and right sides of the airbag 1. The second inflatable portion 13 is adjacent to both left and right sides of the first inflatable portion 12 and mainly restrains and protects the portion extending from both sides of the occupant's chest to both shoulders. The second inflatable portion 13 is set to have a volume of about half or less of the first inflatable portion 12.

[0030] The second expansion part 13 is an air chamber formed to cover the recessed part 15 of the first expansion part 12. Generally speaking, the outer edge part of the second expansion part 13 is formed in an arc shape that complements the virtual same circle C (shown in FIG. 2) whose outer shape is the upper and lower parts of the first expansion part 12 at the position of the recessed part 15, and the inner edge part has a shape along the side edge part of the recessed part 15 of the first expansion part 12. That is, the outer edge part of the second expansion part 13 is convex toward the outer side of the airbag 1, and the inner edge part is convex toward the central part in the left - right direction of the airbag 1. The second expansion part 13 is formed in a shape where the length in the vertical direction becomes longer from the central part of the airbag 1 toward both left and right sides, that is, in a shape that expands in the vertical direction. The second expansion part 13 is formed in a fan - shape when viewed from the front respectively.

[0031] Gas is introduced into the second expansion part 13 through the first expansion part 12. The second expansion part 13 is in fluid communication with the first expansion part 12 through the communication part 30. The communication part 30 is a hole part formed in a round - hole shape and is located at the front part of the first expansion part 12 (airbag 1) on the side opposite to the occupant. In the present embodiment, the communication part 30 is formed in the first non - occupant - side panel 24 of the first expansion part 12 at positions separated from both sides of the introduction part 17. That is, in the first non - occupant - side panel 24, the communication part 30 and the introduction part 17 are arranged side by side left and right. In the illustrated example, the communication part 30 is set to have a larger opening area and a smaller ventilation resistance than the exhaust part 19.

[0032] Preferably, a back - flow prevention valve (check valve) 32 is provided in the communication part 30. The back - flow prevention valve 32 substantially prevents the back - flow of gas from the second expansion part 13 to the first expansion part 12. The back - flow prevention valve 32 is, for example, a flap body formed integrally with the first non - occupant - side panel 24 by a member such as a base fabric to open and close the communication part 30. The back - flow prevention valve 32 is located, for example, outside the first non - occupant - side panel 24, that is, at the front part, and opens the communication part 30 by the gas passing from the first expansion part 12 to the second expansion part 13 and closes the communication part 30 by the gas trying to pass from the second expansion part 13 to the first expansion part 12. Not limited to this, the back - flow prevention valve 32 may have any configuration.

[0033] The second inflatable portion 13 is not provided with a discharge portion for discharging the introduced gas. That is, the second inflatable portion 13 has no openings or holes through which gas substantially passes other than the communication portion 30 for fluid communication with the first inflatable portion 12.

[0034] The second inflatable portion 13 is formed by one or more panels. In the present embodiment, the second inflatable portion 13 has an outer shell formed by a pair of front and rear panels. That is, the second inflatable portion 13 includes a second occupant-side panel 34 as a second opposing portion (second restraint portion) that constitutes the outer shell panel and faces the occupant, and a second non-opposing portion (second non-restraint portion) that does not face the occupant, that is, is located on the front side on the non-occupant side, the second non-occupant-side panel 35. The second occupant-side panel 34 and the second non-occupant-side panel 35 are joined to the first occupant-side panel 23 and the first non-occupant-side panel 24 by a second joining portion 36 such as sewing at the position of the inner edge portion covering the communication portion 30, and are joined to each other by a third joining portion 37 such as sewing at the position of the outer edge portion, and are formed in a bag shape. The second occupant-side panel 34 and the second non-occupant-side panel 35 are each made of, for example, a base fabric, and are also called a base fabric, a panel, a plate, etc. The second occupant-side panel 34 and the second non-occupant-side panel 35 may be formed of a plurality of pieces of fabric, or may be coated. In the present embodiment, the second occupant-side panel 34 and the second non-occupant-side panel 35 are set to have the same or substantially the same outer shape, and particularly the shapes of the outer edge portions are set to be the same or substantially the same.

[0035] When manufacturing the airbag 1, as shown in FIG. 2, the first occupant-side panel 23 and the first non-occupant-side panel 24 are cut into a predetermined shape in advance. First, as shown in FIG. 3(a), the outer edge portions of the first occupant-side panel 23 and the first non-occupant-side panel 24 are joined by the first joining portion 25 to form the first inflatable portion 12. A backflow prevention valve 32 is provided in the communication portion 30 as necessary.

[0036] Next, the second occupant side panel 34 and the second non-occupant side panel 35, which have been previously cut into a predetermined shape, are overlaid on the first occupant side panel 23 and the first non-occupant side panel 24 of the first inflation part 12, and the inner edge parts of the second occupant side panel 34 and the second non-occupant side panel 35 are joined to the first occupant side panel 23 and the first non-occupant side panel 24 by the second joint part 36.

[0037] After that, as shown in FIG. 3(b), the outer edge parts of the second occupant side panel 34 and the second non-occupant side panel 35 are joined by the third joint part 37, and the second inflation part 13 is formed adjacent to the left and right side parts of the first inflation part 12 to complete the airbag 1.

[0038] After inserting and attaching the inflator 2 to the introduction part 17, the completed airbag 1 is folded into a predetermined shape, assembled together with the inflator 2 into a case body of the airbag device, etc., and the airbag device is assembled to a predetermined installation position such as the boss part 5 of the steering wheel 3 inside the vehicle. When folding the airbag 1, since it exhibits a circular outer shape similar to the conventional example, the same folding as the conventional example can be performed, and the cost is not increased by special folding.

[0039] When a collision impact is applied to a vehicle equipped with an airbag device including the airbag 1, the inflator 2 is activated by a control device (not shown), and gas is rapidly injected into the folded airbag 1 through the introduction part 17 by the inflator 2 shown in FIGS. 4(a) and 4(b). Then, first, the first inflation part 12 into which gas is introduced through the introduction part 17 of the airbag 1 expands, and subsequently, the second inflation parts 13 on the left and right side parts into which gas is introduced through the communication part 30 from the first inflation part 12 expand, and due to the inflation pressure, a part of the case body of the airbag device is broken to form an outlet, and it bulges out through this outlet and expands circularly in front of the occupant. At this time, the center part of the first inflation part 12 of the airbag 1 is located such that its vertical and horizontal positions overlap with the center part of the steering wheel 3 or the axis of the steering shaft, the first inflation part 12 covers the upper part to the lower part of the steering wheel 3, and the second inflation parts 13 cover the rim parts 6 on the left and right side parts of the steering wheel 3.

[0040] Thereafter, as shown in FIG. 5(a), the first occupant-side panel 23 of the first inflatable portion 12 and the second occupant-side panel 34 of the second inflatable portion 13 of the deployed airbag 1 receive and restrain the occupant A thrown forward, and mitigate the impact applied to the occupant A. From the completion of inflation of the airbag 1 to the start of restraint of the occupant, as the airbag 1 is pushed forward by the occupant A, a protruding portion 21 that protrudes to the side opposite to the occupant A below the first inflatable portion 12 of the airbag 1 deforms and wraps around to catch on the lower position of the rim portion 6 of the steering wheel 3. Therefore, upward lifting (shifting in, escaping) of the airbag 1 with respect to the steering wheel 3 is suppressed, and the airbag 1 can be retained also in front of the chest of the occupant A.

[0041] As shown in FIG. 5(b), in the first inflatable portion 12 that has received the occupant A, as the first non-occupant-side panel 24 mainly contacts the rim portion 6 of the steering wheel 3 and this rim portion 6 acts as a reaction plate, as the first occupant-side panel 23 is pushed forward by the head etc. of the occupant A moving further forward, a part of the gas inside the first inflatable portion 12 is discharged from inside the exhaust portion 19 to the outside of the airbag 1, preventing an excessive increase in the internal pressure. Also, in the second inflatable portion 13, as the return of the gas to the first inflatable portion 12 is suppressed by the check valve 32 disposed in the communication portion 30, the internal pressure is maintained higher than the internal pressure of the first inflatable portion 12. That is, an internal pressure difference occurs between the first inflatable portion 12 and the second inflatable portion 13. Therefore, the holding force of the second inflatable portion 13 that wraps around both side portions of the rim portion 6 of the steering wheel 3 with respect to the rim portion 6 is improved, suppressing the forward displacement of the airbag 1 and generating an appropriate reaction force with respect to the occupant A, stably protecting the occupant.

[0042] In this way, the airbag 1 includes a first inflation part 12 in which both left and right side parts are recessed toward the central part in a concave shape, and second inflation parts 13 respectively located in the recessed parts on both left and right side parts of the first inflation part 12. Since the inflated state of the first inflation part 12 and the second inflation parts 13 is circular when viewed from the front, special folding is not required, and it can be configured at low cost. Moreover, since the area in contact with the occupant can be ensured, the occupant can be protected more stably. Further, since the second inflation part 13 is formed to cover the recessed part of the first inflation part 12, while ensuring the area for protecting the occupant's shoulders without increasing the size of the airbag 1, the capacity necessary for generating an internal pressure difference with the first inflation part 12 when protecting the occupant can be easily ensured. Furthermore, since it is not necessary to increase the size of the airbag 1, it is not necessary to enhance the output of the inflator 2, and an increase in size associated with the enhancement of the output of the inflator 2 and the resulting cost increase can also be suppressed.

[0043] Since the first inflation part 12 has an exhaust part 19 for discharging a part of the gas to the outside on the side opposite to the occupant, an excessive pressure increase in the first inflation part 12 with which the occupant mainly comes into contact can be avoided. Further, since the second inflation part 13 does not have an exhaust part for discharging the gas to the outside, the second inflation part 13 can maintain the internal pressure even after contact with the occupant. Therefore, the holding force against the rim part 6 can be maintained, and an appropriate reaction force can be generated especially against the occupant's head. Accordingly, even when applied to an irregular-shaped steering wheel 3 having a space part above the rim part 6, the occupant can be stably protected.

[0044] By providing a backflow prevention valve 32 for preventing the backflow of the gas from the second inflation part 13 to the first inflation part 12, the holding force of the second inflation part 13 against the rim part 6 can be improved, and the movement of the inflated airbag 1 upward and forward with respect to the steering wheel 3 can be suppressed.

[0045] By having the protruding portion 21, where the first inflatable portion 12 protrudes downward on the side opposite to the occupant in the inflated state, the inflated airbag 1 can more effectively suppress the upward and forward movement with respect to the steering wheel 3 because the protruding portion 21 catches on the rim portion 6 at the lower part of the steering wheel 3 in the inflated state of the airbag 1.

[0046] In addition, in one embodiment, the outer shapes of the second occupant side panel 34 and the second non-occupant side panel 35 may be made different to change the direction of the reaction force from the second inflatable portion 13.

Industrial Applicability

[0047] The present invention can be suitably used, for example, as an airbag for a driver's seat.

Explanation of Reference Numerals

[0048] 1 Airbag 12 First inflatable portion 13 Second inflatable portion 19 Exhaust portion 21 Protruding portion 32 Backflow prevention valve A Occupant to be protected

Claims

1. An airbag that expands and unfolds by introducing gas from a folded state, A first expansion part in which both left and right side parts are recessed in a concave shape toward the central part and into which the gas is introduced, and a second expansion part that is respectively positioned in the recessed parts on both left and right side parts of the first expansion part and into which the gas is introduced through the first expansion part, and the inflated state of the first expansion part and the second expansion part is circular when viewed from the front An airbag characterized by this.

2. It is provided with a backflow prevention valve that prevents the backflow of gas from the second expansion part to the first expansion part The airbag according to Claim 1, characterized by this.

3. The first expansion part has a protruding part protruding downward on the side opposite to the protected object in the inflated state The airbag according to Claim 1 or 2, characterized by this.

4. The first expansion part has an exhaust part for discharging a part of the gas to the outside on the side opposite to the protected object The airbag according to Claim 1 or 2, characterized by this.

5. The second expansion part does not have a discharge part for discharging gas to the outside The airbag according to Claim 1 or 2, characterized by this.

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