Airbag systems and occupant protection systems

Abstract

To improve mountability while ensuring silencing performance, in a configuration in which an inflator is mounted on an upper part of a vehicle seat.SOLUTION: An airbag device 30 comprises: an inflator 60 mounted on an upper part of a vehicle seat 12, and generating gas upon a vehicle collision; an airbag 32 to which the gas from the inflator 60 is supplied, and which is inflated and deployed from the upper part of the vehicle seat 12 toward a seat front side; and a diffuser 62 for distributing the gas to the airbag. The diffuser 62 comprises: a connection part 62A connected to the inflator 60; and a plurality of branch parts 62B branching from the connection part 62A and each connected to the airbag 32. A silencing part for reducing sound pressure of the gas is provided in the connection part 62A and the plurality of branch parts 62B.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an airbag device and an occupant protection device provided with the airbag device.

Background Art

[0002] The silencer-equipped inflator disclosed in Patent Document 1 below has a gas chamber that generates or stores high-pressure gas for inflating an airbag inside, a first gas hole provided in the wall of the gas chamber for discharging the high-pressure gas, and a silencer connected to the first gas hole for reducing the sound pressure caused by the discharged gas and supplying the gas to the airbag. The silencer has a cylindrical cavity that opens at one end face for expanding the gas discharged from the first gas hole, and a second gas hole that opens at the other end face of the cavity, has a cross-sectional area larger than that of the first gas hole, and supplies the gas expanded in the cavity to the airbag. Since the gas discharged from the gas chamber expands in the cylindrical cavity of the silencer and the pressure decreases, the sound pressure caused by the discharged gas is reduced. Accordingly, even when a silencer-equipped inflator is mounted on a headrest where the distance to the occupant's ear is short, it is said that it will not have an adverse effect on the occupant's ear.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The prior art described above ensures noise reduction performance by having a silencer fixed to the end face of a cylindrical inflator, which has a cylindrical cavity with a larger outer diameter than the inflator. As a result, the overall outer diameter of the silencer-equipped inflator becomes larger, and the overall length of the silencer-equipped inflator becomes longer. Consequently, when mounting the silencer-equipped inflator on top of a vehicle seat, space constraints may be imposed.

[0005] In consideration of the above facts, the present invention aims to provide an airbag device and an occupant protection device equipped with the airbag device that can improve mounting while ensuring noise reduction performance in a configuration in which the inflator is mounted on top of a vehicle seat. [Means for solving the problem]

[0006] The first embodiment of the airbag system includes an inflator mounted on the top of a vehicle seat that generates gas in the event of a vehicle collision, an airbag to which the gas is supplied and which inflates and deploys from the top towards the front of the seat, and a diffuser having a connection part connected to the inflator and a plurality of branching parts that branch off from the connection part and are each connected to the airbag, distributing the gas to the airbag, and having sound-dampening parts provided at least in the plurality of branching parts to reduce the sound pressure of the gas.

[0007] According to the first embodiment, in the event of a vehicle collision, gas generated from an inflator mounted on top of the vehicle seat is supplied to a diffuser and distributed to the airbag, causing the airbag to inflate and deploy from the top of the vehicle seat toward the front of the seat. The diffuser has a connection part connected to the inflator and a plurality of branch parts that branch off from the connection part and are each connected to the airbag, so that the gas is distributed to multiple locations on the airbag through the plurality of branch parts. In this diffuser, sound-reducing parts are provided in at least a plurality of branch parts to reduce the sound pressure of the gas, so that sound-reducing performance can be ensured even if the plurality of branch parts are set to a small diameter. Moreover, since the plurality of branch parts set to a small diameter can be routed to fit the space on top of the vehicle seat, the ease of mounting on top of the vehicle seat can be improved.

[0008] In the second embodiment of the airbag system, the airbag comprises a front and rear chamber including a pair of front and rear extending portions that inflate and deploy forward of the seat, passing on both sides of the head of an occupant seated in the vehicle seat, and an airbag body to which the gas is supplied and which inflates and deploys in front of the occupant, wherein the plurality of branch portions of the diffuser are connected to at least the pair of front and rear extending portions.

[0009] In a second embodiment, the airbag comprises a front and rear chamber and an airbag body. The front and rear chambers include a pair of left and right front extensions that inflate and deploy forward of the seat, passing on both sides of the head of an occupant seated in a vehicle seat. The airbag body is supplied with gas from an inflator through the front and rear chambers and inflates and deploys in front of the occupant. Multiple branches of the diffuser are connected to at least a pair of front and rear extensions of the front and rear chambers. This allows the gas from the inflator to be distributed to each of the front and rear extensions, thereby reducing mounting space, manufacturing costs, and the number of parts compared to, for example, a configuration in which gas is supplied to each of the front and rear extensions from separate inflators.

[0010] In the third embodiment of the airbag device, in the second embodiment, the front and rear chambers include a connecting portion that connects the front ends of the pair of front and rear extending portions in the left-right direction of the seat, and the airbag body inflates and deploys toward the occupant at the rear side of the connecting portion toward the seat, lagging behind the front and rear chambers.

[0011] In the third embodiment, the front and rear chambers of the airbag include a connecting portion that links the front ends of a pair of front and rear extending portions in the left-right direction of the seat, and the airbag body inflates and deploys toward the occupant at the rear side of the connecting portion of the seat, lagging behind the front and rear chambers. When an occupant is restrained, the airbag body compresses in the front-rear direction of the seat while extending the front and rear chambers in the front-rear direction of the seat. This compressive deformation of the airbag body can improve energy absorption performance.

[0012] The airbag device of the fourth embodiment is such that, in any one of the first to third embodiments, the sound-absorbing section is a plurality of partitions provided inside the diffuser, and the inside of the diffuser is divided into a plurality of rooms that communicate with each other by the plurality of partitions.

[0013] In the fourth embodiment, the interior of the diffuser is divided into multiple interconnected chambers by a plurality of partitions installed inside the diffuser. As a result, the diffuser functions as a partition-type silencer, effectively reducing the sound pressure of the gas from the inflator.

[0014] In the fifth embodiment of the airbag system, the partition wall is inclined toward the downstream side in the direction of gas flow within the diffuser, as in the fourth embodiment.

[0015] In the fifth embodiment, since the partition wall provided inside the diffuser is configured as described above, it is possible to suppress obstruction of the gas flow inside the diffuser by the partition wall.

[0016] The occupant protection device according to the sixth aspect includes a vehicle seat on which an occupant sits, and an airbag device according to any one of the first aspect to the fifth aspect mounted on the upper part of the vehicle seat.

[0017] In the sixth aspect, an airbag device is mounted on the upper part of the vehicle seat on which an occupant sits. Since this airbag device is of any one of the first aspect to the fifth aspect, the same effect as any one of the first aspect to the fifth aspect can be obtained.

Advantages of the Invention

[0018] As described above, according to the present invention, in the configuration in which the inflator is mounted on the upper part of the vehicle seat, it is possible to improve the mountability while ensuring the sound absorption performance.

Brief Description of the Drawings

[0019] [Figure 1] It is a perspective view showing a state in which an airbag is inflated and deployed in the occupant protection device according to the embodiment. [Figure 2] It is a side view showing the configuration shown in FIG. 1 as viewed from the left side of the vehicle. [Figure 3] It is a plan view showing the configuration shown in FIG. 1 as viewed from above the vehicle. [Figure 4] It is a front view showing the configuration shown in FIG. 1 as viewed from the front of the vehicle. [Figure 5] It is a front view showing a state in which the airbag is seen through in FIG. 4. [Figure 6] It is a developed view showing the front and rear chambers provided in the airbag. [Figure 7] It is a developed view showing the airbag body provided in the airbag. [Figure 8] It is a front view showing the diffuser and the inflator. [Figure 9] It is a side view showing the diffuser and the inflator. [Figure 10] It is a cross-sectional view showing the diffuser. [Figure 11]This is a cross-sectional view showing a modified example of a diffuser. [Modes for carrying out the invention]

[0020] Hereinafter, an occupant protection device 10 according to an embodiment of the present invention will be described with reference to Figures 1 to 10. In each figure, some reference numerals may be omitted for clarity. Also, the arrows FR, UP, LH, and RH indicated as appropriate in each figure indicate the forward (direction of travel), upward, left, and right directions of the vehicle, respectively. Hereafter, when simply referring to the front / rear, left / right, and up / down directions, unless otherwise specified, they refer to the front / rear direction of the vehicle, the left / right direction of the vehicle, and the up / down direction of the vehicle.

[0021] As shown in Figures 1-5, the occupant protection device 10 consists of a vehicle seat 12 and an airbag device 30. The vehicle seat 12 is either a front seat or a rear seat of a vehicle (automobile). This vehicle seat 12 has a seat cushion 14, a seat back 16 erected above the rear end of the seat cushion 14, and a headrest 18 connected to the upper end of the seat back 16. The front-rear, left-right, up-down directions of this vehicle seat 12 coincide with the front-rear, left-right, up-down directions of the vehicle.

[0022] Figures 1 to 5 illustrate a crash test dummy D, representing a model of the occupant (seater) to be protected, seated on the seat cushion 14 of the vehicle seat 12. Dummy D is, for example, an AM50 (50th percentile of an American adult male) dummy (Hybrid III) used for frontal crash tests. Dummy D is seated in the standard seating position defined by the crash test method, and the vehicle seat 12 is positioned at the standard setting position corresponding to that seating position. Hereafter, for the sake of clarity, dummy D will be referred to as "occupant D".

[0023] The occupant D, seated on the seat cushion 14 of the vehicle seat 12, is restrained to the vehicle seat 12 by a seat belt 22 (see Figures 1 to 3; not shown in Figures 4 and 5) provided by the seat belt device 20. The seat belt device 20 is a three-point seat belt device, and is a so-called seat belt device with a seat, in which a retractor, anchor and buckle (not shown) are provided on the vehicle seat 12.

[0024] The airbag system 30 comprises an airbag 32, an inflator 60 (see Figure 2), and a diffuser 62 (see Figures 2 and 3). Normally, the airbag 32 is folded and stored together with the inflator 60 and diffuser 62 in a module case (not shown). The module case is located at the rear of the upper part of the vehicle seat 12 (specifically, behind the upper end of the seat back 16 and the headrest 18) and is fixed to the upper end of the seat back 16 or to the vehicle body (not shown).

[0025] The airbag 32 receives gas from the inflator 60 and inflates and deploys (deploys and inflates) from the rear to the front of the upper part of the vehicle seat 12. The airbag 32 has front and rear chambers 34, an ejection chamber 39, and an airbag body 40. The front and rear chambers 34 have a pair of front and rear extending sections 34A that inflate and deploy forward, passing on both sides of the occupant D's head H, and a connecting section 34B that connects the front ends of the pair of front and rear extending sections 34A in the left-right direction. The ejection chamber 39 inflates and deploys above the headrest 18 and connects the rear ends of the pair of front and rear extending sections 34A in the left-right direction. The airbag body 40 inflates and deploys toward the occupant D side (rear side) behind the front and rear chambers 34 at the rear side of the connecting section 34B.

[0026] The front and rear chambers 34 are formed into a long bag shape by overlapping two long base fabrics 36 and 38 shown in Figure 6 and sewing the periphery at the sewing section S1. The extrusion chamber 39 is not shown in the figure, but it is formed into a long bag shape by overlapping two long base fabrics and sewing the periphery at the sewing section. The airbag body 40 is formed into a bag shape by folding a single base fabric 42 shown in Figure 7 along four fold lines L1, L2, L3, and L4 and sewing it at the sewing section S2. At this sewing section S2, sewing lines SL21 and SL22 are sewn together, sewing lines SL23 and SL24 are sewn together, sewing lines SL25 and SL26 are sewn together, and sewing lines SL27 and SL28 are sewn together. The base fabrics 36, 38, 42 and the base fabric of the extrusion chamber 39 are made of, for example, nylon or polyester fabric. One or both of the two base fabrics 36 and 38 that make up the front and rear chambers 34 are made of a base fabric that is less stretchable than the base fabric 42 that makes up the airbag body 40.

[0027] The longitudinal ends of the front and rear chambers 34 are a pair of front and rear extensions 34A, and the longitudinal center of the front and rear chambers 34 is a connecting portion 34B. Each of the pair of front and rear extensions 34A is formed in the shape of a long tube. The connecting portion 34B is a roughly T-shaped bag that communicates with each of the front and rear extensions 34A. The ends of the pair of front and rear extensions 34A opposite to the connecting portion 34B (rear ends) are connected to both longitudinal ends of the extrusion chamber 39. The extrusion chamber 39 is connected to the pair of front and rear extensions 34A.

[0028] The connecting portion 34B of the front and rear chambers 34 is sewn to the airbag body 40 at a sewing portion S3 (see Figures 6 and 7) located in the center of the connecting portion 34B. The sewing portion S3 is, for example, roughly trapezoidal in shape. A communication hole 48 is formed on the inside of the sewing portion S3, connecting the inside of the connecting portion 34B and the inside of the airbag body 40. The communication hole 48 is, for example, roughly trapezoidal in shape. This communication hole 48 is composed of a through hole 50 formed in the base fabric 36 of the front and rear chambers 34 and a through hole 52 formed in the base fabric 42 of the airbag body 40.

[0029] The front and rear chambers 34, the extrusion chamber 39, and the airbag body 40 are normally folded in a predetermined folding method, such as roll folding or bellows folding, and housed in a module case. Gas from the inflator 60 is supplied to the pair of front and rear extensions 34A of the front and rear chambers 34 and the extrusion chamber 39 via a diffuser 62, which will be described in detail later. The inflator 60 is a combustion-type or cold-gas-type cylinder inflator that generates gas when it operates. The operation of this inflator 60 is controlled by a control device (not shown) and generates gas in the event of a vehicle collision.

[0030] The inflator 60 described above is positioned on the upper part of the vehicle seat 12 (in this case, behind the upper end of the seat back 16) with its axial direction aligned with the vertical direction of the seat back 16. The inflator 60 is provided with, for example, a pair of upper and lower stud bolts. The pair of stud bolts pass through, for example, a frame of the seat back 16 (not shown), and nuts are screwed onto each stud bolt. In this way, the inflator 60 is fixed to the frame of the seat back 16.

[0031] When the inflator 60 is activated, gas generated from the gas ejection port 60A located at the upper end of the inflator 60 is supplied through the diffuser 62 to the pair of front and rear extensions 34A and the extrusion chamber 39. This causes the pair of front and rear extensions 34A and the extrusion chamber 39 to begin inflating and deploying. The gas supplied to the pair of front and rear extensions 34A and the extrusion chamber 39 flows toward the connecting portion 34B and is supplied into the airbag body 40 through the communication hole 48. As a result, the airbag body 40 inflates and deploys to the front and rear chambers 34 and the extrusion chamber 39 with a delay. During the inflation and deployment of the airbag 32, a tear line (not shown) formed on the module case is configured to rupture upon receiving the inflation pressure of the airbag 32. This allows the airbag 32 to inflate and deploy to the outside of the module case.

[0032] The inflated and deployed pair of front-to-rear extensions 34A extend in the front-to-rear direction on both the left and right sides of the occupant D's head H, facing the head H from both sides with a gap between them. The pair of front-to-rear extensions 34A are pulled diagonally downward and rearward by a pair of rear tethers 54, which will be described later, so that they are tilted downward toward the front. The front ends of the inflated and deployed pair of front-to-rear extensions 34A are connected in the left-to-right direction by an inflated and deployed connecting part 34B. As shown in Figure 3, the front-to-rear chamber 34, including the pair of front-to-rear extensions 34A and the connecting part 34B, inflates and deploys in a U-shape that opens rearward in a plan view.

[0033] As shown in Figures 1, 2, 4, and 5, an enlarged portion 34B1 is provided at the left-right center of the inflated and deployed connecting portion 34B, with a vertical dimension greater than that of the left and right ends of the connecting portion 34B. This enlarged portion 34B1 protrudes downward from the left and right ends of the connecting portion 34B. The aforementioned communication hole 48 is formed in this enlarged portion 34B1. This communication hole 48 is located on the rear side of the left-right center of the inflated and deployed connecting portion 34B. Gas from the inflator 60 is supplied to the airbag body 40 in a rearward direction through the communication hole 48. As a result, the airbag body 40 inflates and deploys towards the occupant D side (rear side) behind the front and rear chambers 34, after the front and rear chambers 34 have inflated and deployed.

[0034] During the passage described above, the airbag body 40 is pushed forward by the extrusion chamber 39, which inflates and deploys before the airbag body 40, thereby promoting the forward inflation and deployment of the airbag body 40. The inflated and deployed airbag body 40 faces the occupant D's head H, chest C, and abdomen B from the front, with a gap between them. As a result, the occupant D, which is inertially moving forward due to the impact of the vehicle collision, is restrained from the front by the inflated and deployed airbag body 40. During this occupant restraint, the front and rear chambers 34 are stretched in the front-rear direction, and the airbag body 40 is compressed in the front-rear direction. The shape of the airbag body 40 is set so that it is sandwiched between the occupant D's thigh T and chest C from the middle to the later stages of occupant restraint.

[0035] As shown in Figures 1 to 6, the airbag 32 is fitted with a pair of left and right rear tethers 54, a pair of left and right front upper tethers 56, and a pair of left and right front lower tethers 58. The rear tethers 54, front upper tethers 56, and front lower tethers 58 are made of long strips of fabric, such as nylon or polyester. The fabrics that make up the rear tethers 54, front upper tethers 56, and front lower tethers 58 are made to be less stretchable than the base fabrics 36, 38 that make up the front and rear chambers 34 and the base fabric 42 that makes up the airbag body 40. This resistance to stretching can be adjusted by the material and thickness of the fabric.

[0036] Each end of the pair of rear tethers 54 is secured (sewn) to the longitudinal middle portion of the pair of front-rear extensions 34A (specifically, the front portion of each inflated and deployed front-rear extension 34A). The other end of each of the pair of rear tethers 54 is secured to the seat back 16 or the vehicle body (not shown) behind the occupant D. When the airbag 32 is inflated and deployed, the pair of rear tethers 54 extend in the front-rear direction below the pair of front-rear extensions 34A. In this state, the pair of rear tethers 54 are inclined downward toward the rear. This configuration causes the pair of front-rear extensions 34A to be pulled diagonally downward toward the rear by the pair of rear tethers 54. This suppresses the airbag 32 from swinging in the vertical and front-rear directions when the airbag 32 has finished inflating and deploying.

[0037] As described above, when the pair of front and rear extensions 34A are retracted, the lower surfaces of the pair of front and rear extensions 34A are configured to contact the left and right shoulders K of the occupant D when the occupant is restrained by the airbag 32. When the occupant is restrained by the airbag 32, the airbag body 40 is supported by the tensile load of the pair of front and rear extensions 34A and the pair of rear tethers 54. In this embodiment, the occupant D is AM50, but even if the occupant D is AM95 (95th percentile of adult American males) or AF05 (5th percentile of adult American females), the length of the pair of rear tethers 54 is set so that the lower surfaces of the pair of front and rear extensions 34A contact the left and right shoulders K of the occupant D.

[0038] The pair of front upper tethers 56 connect the left and right sides of the upper front portion of the airbag body 40 that inflates and deploys upward from the front and rear chambers 34 to the front portion of the pair of front and rear extensions 34A. One end of each pair of front upper tethers 56 is sewn to the left and right sides of the upper front portion of the airbag body 40 that inflates and deploys upward from the front and rear chambers 34. The other end of each pair of front upper tethers 56 is sewn to the front portion of the pair of front and rear extensions 34A. The pair of front upper tethers 56 prevent the airbag body 40 from rotating upward around the connecting portion 34B when the airbag 32 has finished inflating and deploying.

[0039] The pair of front lower tethers 58 connect the left and right sides of the lower part of the airbag body 40 that inflates and deploys below the front and rear chambers 34 to the front of the pair of front and rear extensions 34A, respectively. One end of each pair of front lower tethers 58 is sewn to the left and right sides of the lower part of the airbag body 40 that inflates and deploys below the front and rear chambers 34, respectively. The other end of each pair of front lower tethers 58 is sewn to the front of the pair of front and rear extensions 34A, respectively. The pair of front lower tethers 58 prevent the airbag body 40 from rotating downward around the connecting portion 34B when the airbag 32 has finished inflating and deploying.

[0040] The airbag system 30 described above includes a control unit (ECU), not shown, which controls the operation of the inflator 60. The control unit is electrically connected to the inflator 60 and a collision sensor, not shown. Based on information from the collision sensor, the control unit is capable of detecting or predicting the occurrence (or inevitability of) various types of frontal collisions for the applied vehicle, according to the collision type described later.

[0041] The control unit is configured to activate the inflator 60 when it detects or predicts a frontal collision based on information from the collision sensor. The types of frontal collisions that trigger the control unit to activate the inflator 60 include not only full-wrap frontal collisions but also offset frontal collisions such as oblique collisions and minute-wrap collisions.

[0042] The diffuser 62, which distributes gas from the inflator 60 to the airbag 32, has a connection part 62A connected to the inflator 60 and a number of branching parts 62B (three in this case) branching from the connection part 62A, as shown in Figures 8 and 9, and is configured as a four-pronged tubular shape. This diffuser 62 is made of a heat-resistant material such as metal. The connecting portion 62A is fixed to the inflator 60 with the upper end of the inflator 60 fitted inside. The three branching portions 62B consist of branching portion 62B1, which extends upward from the connecting portion 62A and whose tip is bent forward on the upper side of the headrest 18; branching portion 62B2, which extends to the left from the connecting portion 62A and whose tip is bent forward on the left side of the headrest 18; and branching portion 62B3, which extends to the right from the connecting portion 62A and whose tip is bent forward on the right side of the headrest 18. These branching portions 62B1, 62B2, and 62B3 are routed so as to extend from the rear side of the headrest 18, avoiding the headrest 18 and extending forward.

[0043] The tip of the branch portion 62B1 extending upward is inserted into a connection hole (not shown) formed in the longitudinal center of the extrusion chamber 39. The edge of the connection hole in the extrusion chamber 39 is fixed to the tip of the branch portion 62B1 using, for example, a metal band. The tip of the branch portion 62B2 extending to the left is inserted into a connection hole (not shown) formed at the rear end of the left front-rear extension portion 34A. The edge of the connection hole in the left front-rear extension portion 34A is fixed to the tip of the branch portion 62B2 using, for example, a metal band. The tip of the branch portion 62B3 extending to the right is inserted into a connection hole (not shown) formed at the rear end of the right front-rear extension portion 34A. The edge of the connection hole in the right front-rear extension portion 34A is fixed to the tip of the branch portion 62B3 using, for example, a metal band.

[0044] In the diffuser 62 described above, branch section 62B1 communicates with the extrusion chamber 39, branch section 62B2 communicates with the front-rear extension section 34A on the left side, and branch section 62B3 communicates with the front-rear extension section 34A on the right side. This configuration ensures that the gas generated from the gas ejection section 60A of the inflator 60 is distributed to the extrusion chamber 39 and the left and right front-rear extension sections 34A through branch sections 62B1, 62B2, and 62B3.

[0045] The diffuser 62 is provided with multiple (in this case, many) partition walls 66. Specifically, partition walls 66 are provided within the connecting section 34B and within the three branching sections 62B. The many partition walls 66 constitute a sound-dampening section 64. The interior of the diffuser 62 is divided into multiple (in this case, many) rooms 68 that are interconnected by the many partition walls 66. Each partition wall 66 is made of, for example, metal and has a frustoconical shape (like a disc spring) that is inclined (reduced in diameter) toward the downstream side in the gas flow direction F within the diffuser 62. An opening (not shown) is formed in the center of each partition wall 66, and the multiple rooms 68 are interconnected through the opening in each partition wall 66. As a result, the diffuser 62 functions as a partition-type silencer, reducing the sound pressure of the gas from the inflator 60.

[0046] (Mechanism of Action and Effects) Next, the operation and effects of this embodiment will be described.

[0047] The occupant protection device 10 according to this embodiment includes a vehicle seat 12 in which an occupant D of the vehicle sits, and an airbag device 30 that protects the occupant D in the event of a vehicle collision. In this airbag device 30, when a vehicle collision occurs, gas generated from an inflator 60 mounted on the top of the vehicle seat 12 is guided to a diffuser 62 and distributed to the airbag 32, causing the airbag 32 to inflate and deploy forward from the top of the vehicle seat 12.

[0048] The diffuser 62 has a connection section 62A connected to the inflator and a plurality of branch sections 62B that branch off from the connection section 62A and are each connected to the airbag 32, so that the gas is distributed to multiple locations on the airbag 32 through the plurality of branch sections 62B.In this diffuser 62, sound-dampening sections 64 (a plurality of bulkheads 66) that reduce the sound pressure of the gas are provided in the connection section 62A and the plurality of branch sections 62B, so even if the connection section 62A and the plurality of branch sections 62B are set to a small diameter, the sound pressure of the gas is reduced in each of the connection section 62A and the plurality of branch sections 62B, thereby ensuring sound-dampening performance.As a result, even if the inflator 60 is mounted near the headrest 18, which is close to the ears of the occupant D, it is possible to prevent adverse effects on the ears of the occupant D.Moreover, since the plurality of branch sections 62B, which are set to a small diameter, can be routed to fit the space above the vehicle seat 12, the mounting capacity above the vehicle seat 12 can be improved. Furthermore, since the diffuser 62, which distributes gas to multiple points in the airbag 32, functions as a silencer, there is no need to attach a separate silencer to the inflator 60.

[0049] In this embodiment, the airbag 32 includes front and rear chambers 34, an extrusion chamber 39, and an airbag body 40. The front and rear chambers 34 include a pair of left and right front and rear extensions 34A that inflate and deploy forward, passing over both sides of the head H of the occupant D seated in the vehicle seat 12. The extrusion chamber 39 inflates and deploys above the headrest 18, connecting the rear ends of the pair of front and rear extensions 34A in the left-right direction. The airbag body 40 is supplied with gas from the inflator 60 through the front and rear chambers 34 and inflates and deploys in front of the occupant D. The multiple branch sections 62B of the diffuser 62 are connected to the pair of front and rear extensions 34A and the extrusion chamber 39. This allows the gas from the inflator 60 to be distributed to the pair of front and rear extensions 34A and the extrusion chamber 39, respectively, thus reducing mounting space, manufacturing costs, and the number of parts compared to a configuration in which gas is supplied to the pair of front and rear extensions 34A and the extrusion chamber 39 from separate inflators.

[0050] Furthermore, in this embodiment, the front and rear chambers 34 include a connecting portion 34B that connects the front ends of a pair of front and rear extending portions 34A in the left-right direction, and the airbag body 40 inflates and deploys toward the occupant D at the rear side of the connecting portion 34B, lagging behind the front and rear chambers 34. When the occupant D is restrained, the airbag body 40 compresses in the front and rear direction while extending the front and rear chambers 34 in the front and rear direction. This compressive deformation of the airbag body 40 can improve the energy absorption performance.

[0051] Furthermore, in this embodiment, the sound-dampening section 64 is formed by a plurality of partition walls 66 provided inside the diffuser 62, and the inside of the diffuser 62 is divided into a plurality of interconnected chambers 68 by the plurality of partition walls 66. As a result, the diffuser 62 functions as a partition-type sound-dampening device, which effectively reduces the sound pressure of the gas from the inflator 60. In addition, the plurality of partition walls 66 also function as reinforcing members that reinforce the diffuser 62, so the thickness of the diffuser 62 can be reduced.

[0052] Furthermore, each partition wall 66 has a frustoconical shape that slopes (reduces in diameter) toward the downstream side in the gas flow direction F (see Figure 10) within the diffuser 62. Therefore, obstruction of the gas flow within the diffuser 62 by the partition walls 66 can be suppressed.

[0053] In the above embodiment, it is preferable to adjust the number of partition walls 66, the direction of inclination of the partition walls 66, and the respective wall thicknesses of the diffuser 62 and partition walls 66, taking into consideration the gas flow within the diffuser 62, sound pressure, strength, etc.

[0054] Furthermore, as shown in the modified example in Figure 11, the sound-absorbing section 70 may be composed of a plurality of partition walls 72 that are inclined toward the downstream side in the gas flow direction F within the diffuser 62 and are offset from each other in the flow direction F.

[0055] Furthermore, while the above embodiments and modifications describe a case in which the sound-absorbing sections 64 and 70 are composed of multiple partitions 66 and 72 provided inside the diffuser 62, the invention is not limited to this. The sound-absorbing sections may be, for example, glass wool or steel wool provided inside the diffuser 62.

[0056] Furthermore, in the above embodiment, the airbag 32 is configured to have front and rear chambers 34, an extrusion chamber 39, and an airbag body 40, but the configuration of the airbag 32 is not limited to this and can be changed as appropriate. For example, the airbag 32 can be changed to a configuration that does not have an extrusion chamber 39, but has left and right front and rear chambers 34 and an airbag body 40.

[0057] Furthermore, the present invention can be implemented with various modifications without departing from its spirit. Of course, the scope of the present invention is not limited to the embodiments described above. [Explanation of Symbols]

[0058] 10. Crew protection devices 12 Vehicle seats 30 Airbag system 32 airbags 34 Front and rear chambers 34A Front and rear extension part 34B Connecting part 40 Airbag Unit 60 Inflator 62 Diffuser 62A Connection 62B Branch 64 Silencer 66 Bulkhead 68 rooms 70 Silencer 72 Bulkhead D Crew H head

Claims

1. It is mounted on top of the vehicle seat and is an inflator that generates gas in the event of a vehicle collision, An airbag comprising: a front and rear chamber including a pair of front and rear extending portions that are supplied with the aforementioned gas and inflate and deploy from the top toward the front of the seat, and that inflate and deploy toward the front of the seat, passing on both the left and right sides of the head of the occupant seated in the vehicle seat; an airbag body that is supplied with the aforementioned gas through the front and rear chambers and inflates and deploys in front of the occupant; and an extrusion chamber that connects the rear ends of the pair of front and rear extending portions in the left-right direction of the seat. A diffuser having a connection part connected to the inflator, and a plurality of branching parts that branch off from the connection part and are each connected to the airbag, the tips of the plurality of branching parts curve toward the front of the seat and are in communication with the pair of front and rear chambers and the extrusion chamber, distributing the gas to the airbag, and having sound-dampening parts provided at least in the plurality of branching parts to reduce the sound pressure of the gas, An airbag system equipped with an airbag.

2. The front and rear chambers include a connecting portion that connects the front ends of the pair of front and rear extending portions in the left-right direction of the seat. The airbag device according to claim 1, wherein the airbag body inflates and deploys toward the occupant at the rear side of the seat of the connecting portion, with a delay between the front and rear chambers.

3. The sound-dampening section consists of a plurality of partitions provided inside the diffuser. The airbag device according to claim 1 or claim 2, wherein the interior of the diffuser is divided into a plurality of rooms that communicate with each other by the plurality of partition walls.

4. The airbag device according to claim 3, wherein the partition wall is inclined toward the downstream side in the direction of gas flow within the diffuser.

5. A vehicle seat in which an occupant sits, An airbag device according to claim 1 or claim 2, mounted on the upper part of the vehicle seat, Crew protection device equipped with a occupant protection device.

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