Airbag device and occupant protection device

Abstract

The invention provides an airbag device and an occupant protection device. The airbag apparatus includes: an inflator installed in an upper portion of a vehicle seat and generating gas when a vehicle collision occurs; an airbag to which the gas is supplied from the inflator, and which is inflated and deployed from the upper portion of the vehicle seat toward a front side of the vehicle seat; and a diffuser that distributes the gas to the airbag. The diffuser includes a connecting portion and a plurality of branch portions, the connecting portion is connected to the inflator, and the plurality of branch portions are respectively branched from the connecting portion and connected to the airbag. The diffuser includes a silencing portion at least in the plurality of branch portions. The silencing part reduces the sound pressure of the gas.

Description

Technical Field

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

[0002] The inflator equipped with a silencer disclosed in Japanese Registered Utility Model No. 3015513 includes: an air chamber for generating or storing therein high-pressure gas for inflating an airbag; a first air hole provided on the wall of the air chamber for discharging the high-pressure gas; and a silencer connected to the first air hole to supply gas to the airbag while reducing the sound pressure generated by the discharged gas. The silencer has a cylindrical cavity at one end surface thereof, a first air hole opening into the cavity, and the gas discharged from the first air hole expands in the cavity; and has a second air hole opening at the other end surface of the cavity, the second air hole having a larger cross-sectional area than the first air hole, for supplying the gas expanding in the cavity to the airbag. The gas discharged from the air chamber expands in the cylindrical cavity of the silencer, and its pressure is reduced, so that the sound pressure generated by the discharged gas is reduced. This is said to prevent the ears of the occupant from being adversely affected even when the inflator equipped with the silencer is installed in the headrest close to the ears of the occupant. Summary of the invention

[0003] In the above related art, the silencer fixed to the end surface of the cylinder-type inflator has a cylindrical cavity having an outer diameter larger than that of the inflator, thereby ensuring the silencing performance. Therefore, the total outer diameter of the inflator equipped with the silencer becomes larger, the total length of the inflator equipped with the silencer becomes longer, etc. Therefore, when the inflator equipped with the silencer is installed on the upper part of the vehicle seat, it can be expected that the space may be limited.

[0004] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an airbag device and an occupant protection device equipped with the airbag device, in which in a configuration in which an inflator is mounted on an upper portion of a vehicle seat, mountability can be improved while ensuring sound absorbing performance.

[0005] The airbag device according to the first scheme includes an inflator, an airbag, and a diffuser. The inflator is installed in the upper part of the vehicle seat, and generates gas when a vehicle collision occurs. The gas is supplied to the airbag, and the airbag expands and deploys from the upper part of the vehicle seat toward the front side of the vehicle seat. The diffuser includes a connecting portion and a plurality of branch portions, and distributes the gas to the airbag. The connecting portion is connected to the inflator. The plurality of branch portions are respectively branched from the connecting portion and connected to the airbag. The diffuser includes a muffler at least in the plurality of branch portions. The muffler reduces the sound pressure of the gas.

[0006] According to the first scheme, when a vehicle collision occurs, the gas generated by the inflator installed in the upper part of the vehicle seat is supplied to the diffuser and distributed to the airbag, and the airbag expands and deploys from the upper part of the vehicle seat toward the front side of the vehicle seat. The diffuser has a connecting portion and a plurality of branch portions, the connecting portion is connected to the inflator, the plurality of branch portions branch from the connecting portion and are respectively connected to the airbag, whereby the gas is distributed to a plurality of positions in the airbag through the plurality of branch portions. In the diffuser, at least a plurality of branch portions are provided with a muffler that reduces the sound pressure of the gas, so that even when each branch portion is set to have a small diameter, the muffler performance can be ensured. In addition, the branch portions that are respectively set to have a small diameter can be routed to fit into the space at the upper part of the vehicle seat, and thus the installability at the upper part of the vehicle seat can be improved.

[0007] In the airbag device according to the second scheme, in the first scheme, the airbag may include a front and rear chamber, which includes a pair of extensions and an airbag body. The pair of extensions are configured to expand and deploy toward the front side of the vehicle seat through the left and right sides of the head of the occupant sitting in the vehicle seat, and the pair of extensions may extend in the front-to-back direction. The airbag body is supplied with the gas through the front and rear chambers, and the airbag body may expand and deploy in front of the occupant. The plurality of branches of the diffuser may be connected to at least the front and rear extensions.

[0008] According to the second scheme, the airbag has front and rear chambers and an airbag body. The front and rear chambers include a pair of extensions that expand and unfold toward the front side of the vehicle seat through the left and right sides of the head of an occupant sitting in the vehicle seat. The airbag body is supplied with gas from the inflator through the front and rear chambers, and expands and unfolds in front of the occupant. A plurality of branches of the diffuser are connected to at least a pair of extensions of the front and rear chambers. This enables the gas from the inflator to be distributed to each extension, and therefore, for example, compared to a configuration in which gas is supplied to each extension from a separate inflator, the installation space, manufacturing costs, and the number of components can be reduced.

[0009] In the airbag device according to the third scheme, in the second scheme, the front and rear chambers may include a connecting portion connecting the front end portions of the pair of extension portions in the left-right direction of the vehicle seat, and at the rear side of the connecting portion in the front-to-back direction of the vehicle seat, the airbag body may inflate and unfold toward the occupant side later than the front and rear chambers.

[0010] According to the third aspect, the front and rear chambers of the airbag include a connecting portion connecting the front end portions of a pair of extensions in the left-right direction of the vehicle seat, and the airbag body expands and deploys toward the passenger side later than the front and rear chambers at the rear side of the connecting portion in the front-rear direction of the vehicle seat. When the passenger is restrained, the airbag body is compressed in the front-rear direction of the vehicle seat while the front and rear chambers are extended in the front-rear direction of the seat. Such compression deformation of the airbag body can improve energy absorption performance.

[0011] In the airbag device according to the fourth aspect, in any one of the first to third aspects, the muffler may be a plurality of partition walls provided inside the diffuser, and the interior of the diffuser may be partitioned into a plurality of chambers by the plurality of partition walls, and the plurality of chambers may be connected to each other.

[0012] According to the fourth aspect, the interior of the diffuser is partitioned into a plurality of chambers by a plurality of partition walls provided inside the diffuser, and the plurality of chambers communicate with each other. Therefore, the diffuser functions as a partition wall type silencer, by which the sound pressure of the gas from the inflator can be effectively reduced.

[0013] In the airbag device according to a fifth aspect, in the fourth aspect, the plurality of partition walls may be inclined toward a downstream side in a flow direction of the gas flowing inside the diffuser.

[0014] According to the fifth aspect, the plurality of partition walls provided in the diffuser are configured as described above, and therefore, it is possible to suppress the flow of the gas flowing inside the diffuser from being blocked by the plurality of partition walls.

[0015] An occupant protection device according to a sixth aspect may include: a vehicle seat in which an occupant sits; and the airbag device according to any one of the first to fifth aspects installed in an upper portion of the vehicle seat.

[0016] According to the sixth aspect, the airbag device is installed in the upper portion of the vehicle seat where the occupant sits. The airbag device is the airbag device according to any one of the first to fifth aspects, and thus can obtain the same effects as any one of the first to fifth aspects.

[0017] As described above, according to the present invention, in the configuration in which the inflator is mounted on the upper portion of the vehicle seat, the mountability can be improved while the sound absorbing performance is ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described hereinafter with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0019] Figure 1 A perspective view illustrating a state in which an airbag is inflated and deployed in an occupant protection device according to an embodiment;

[0020] Figure 2 When viewed from the left side of the vehicle Figure 1 a side view of the construction shown;

[0021] Figure 3 For the state of being viewed from above the vehicle Figure 1 a plan view of the construction shown;

[0022] Figure 4 When viewed from the front of the vehicle Figure 1 a front view of the construction shown;

[0023] Figure 5 For passing through Figure 4 A front view of the state of the airbag viewing;

[0024] Figure 6 An expanded view showing the front and rear chambers of the airbag;

[0025] Figure 7 is an expanded view of an airbag body of the airbag;

[0026] Figure 8 A front view of the diffuser and the inflator is shown;

[0027] Fig. 9 A side view of the diffuser and the inflator is shown;

[0028] Fig.10 is a cross-sectional view illustrating a diffuser; and

[0029] Fig.11 The figure is a cross-sectional view showing a modified example of the diffuser. DETAILED DESCRIPTION

[0030] In the following we will refer to Figures 1 to 10 An occupant protection device 10 according to an embodiment of the present invention is described. It is noted in the accompanying drawings that some reference numerals may be omitted for ease of viewing the accompanying drawings. Moreover, the arrow "front" (FR), arrow "up" (UP), arrow "left" (LH), and arrow "right" (RH) appropriately shown in the accompanying drawings indicate the forward direction (forward direction), upward direction, left direction, and right direction of the vehicle, respectively. In the following, when the front-to-back direction, left-to-right direction, and up-down direction are simply used for description, these mean the front-to-back direction of the vehicle, the left-to-right direction of the vehicle, and the up-down direction of the vehicle, unless otherwise specified.

[0031] like Figures 1 to 5 As shown, the occupant protection device 10 is composed of a vehicle seat 12 and an airbag device 30. The vehicle seat 12 is a front seat or a rear seat of a vehicle (car). The vehicle seat 12 includes a seat cushion 14, a seat back 16 erected on the upper side of the rear end of the seat cushion 14, and a headrest 18 connected to the upper end of the seat back 16. The front-to-back direction, left-to-right direction, and up-down direction of the vehicle seat 12 are consistent with the front-to-back direction, left-to-right direction, and up-down direction of the vehicle.

[0032] exist Figures 1 to 5 It is noted that a crash test dummy D for the crash test is shown in a state of sitting on the seat cushion 14 of the vehicle seat 12 as a model of the occupant (seated person) to be protected. For example, the crash test dummy D is a frontal crash test dummy (hybrid type III) AM50 (50 percent of the American male dummy). The crash test dummy D is seated in a standard sitting posture determined by the crash test method, and the vehicle seat 12 is located in a standard setting position corresponding to the sitting posture. In the following, the crash test dummy D will be referred to as "occupant D" for ease of description.

[0033] An occupant D sitting on the seat cushion 14 of the vehicle seat 12 is connected to a seat belt 22 (see FIG. Figures 1 to 3 ,from Figure 4 and Figure 5 The seat belt device 20 is a three-point seat belt device, and is a seat belt device attached to a seat, in which a retractor omitted from illustration and an anchor and a buckle (reference numerals omitted) are provided to the vehicle seat 12.

[0034] The airbag device 30 includes an airbag 32, an inflator 60 (see Figure 2 ) and diffuser 62 (see Figure 2 and Figure 3 ). During normal use, the airbag 32 is housed in a module housing omitted from the illustration together with the inflator 60 and the diffuser 62 in a folded state. The module housing is arranged behind the upper portion of the vehicle seat 12 (specifically, the upper end portion of the seat back 16 and the rear of the headrest 18), and is fixed to the upper end portion of the seat back 16 or the vehicle body omitted from the illustration.

[0035] The airbag 32 receives a supply of gas from the inflator 60, and expands and deploys (expands and expands) from the rear side (i.e., rear side) of the upper part of the vehicle seat 12 toward the front side (i.e., front side). The airbag 32 has a front and rear chamber 34, a propulsion chamber 39, and an airbag body 40. The front and rear chamber 34 has a pair of left and right front and rear extensions 34A (also referred to as a pair of extensions) that expand and deploy forward through the left and right sides of the head H of the occupant D, and a connecting portion 34B that connects the front end portions of the front and rear extensions 34A in the left and right direction. The propulsion chamber 39 expands and deploys toward the upper side of the headrest 18, and connects the rear end portions of the front and rear extensions 34A in the left and right direction. The airbag body 40 expands and deploys toward the occupant D side (rear side) later than the front and rear chamber 34 on the rear side of the connecting portion 34B.

[0036] By Figure 6 The two elongated base fabric pieces 36 and 38 shown are placed one on top of the other and their peripheral edges are sewn in the sewing section S1 to form the front and rear chambers 34, thereby producing an elongated bag-like article. The two elongated base fabric pieces are placed one on top of the other and their peripheral edges are sewn in the sewing section to form the propulsion chamber 39, thereby producing an elongated bag-like article, which is omitted from the figure. Figure 7 As shown, the airbag body 40 is formed into a bag-like article by folding a base fabric sheet 42 along four folding lines L1, L2, L3 and L4 and sewing it in a sewing section S2. In the sewing section S2, the sewing line SL21 is sewn with the sewing line SL22, the sewing line SL23 is sewn with the sewing line SL24, the sewing line SL25 is sewn with the sewing line SL26, and the sewing line SL27 is sewn with the sewing line SL28. For example, the base fabric sheets 36, 38 and 42, and the base fabric sheet of the propulsion chamber 39 are made of a fabric such as nylon or polyester fiber. One or both of the two base fabric sheets 36 and 38 constituting the front and rear chambers 34 are fabric sheets that are more difficult to stretch than the base fabric sheet 42 constituting the airbag body 40.

[0037] The front and rear chambers 34 constitute front and rear extensions 34A at both end sides in the longitudinal direction thereof, and the middle portion of the front and rear chambers 34 in the longitudinal direction thereof constitutes a connecting portion 34B. Each front and rear extension 34A is formed in a long tubular shape. The connecting portion 34B has a bag shape of a substantially letter T that connects each of the front and rear extensions 34A. Both ends in the longitudinal direction of the propulsion chamber 39 are connected to the ends (rear ends) of the front and rear extensions 34A on the side opposite to the connecting portion 34B. The propulsion chamber 39 is connected to the front and rear extensions 34A.

[0038] The connecting portion 34B of the front and rear chambers 34 has a sewing section S3 (see Figure 6 and Figure 7 ) is sewn to the airbag body 40. The sewn section S3 has a substantially inverted trapezoidal shape in one example. A communication hole 48 is formed inside the sewn section S3 so that the inside of the connection portion 34B can communicate with the inside of the airbag body 40. In one example, the communication hole 48 has a substantially inverted trapezoidal shape. The communication hole 48 is composed of a through hole 50 formed in the base fabric sheet 36 of the front and rear chambers 34 and a through hole 52 formed in the base fabric sheet 42 of the airbag body 40.

[0039] The front and rear chambers 34, the propulsion chamber 39, and the airbag body 40 are folded according to a predetermined folding method, such as rolling folding, bellows folding, etc., and are housed in the module housing during normal use. Gas from the inflator 60 is supplied to the front and rear extensions 34A of the front and rear chambers 34 via a diffuser 62 to be described in detail later, and is supplied to the propulsion chamber 39. The inflator 60 is a combustion type or cold air type cylinder type inflator, and generates gas when operating. The operation of the inflator 60 is controlled by a control device omitted from the illustration, and the inflator 60 generates gas if a vehicle collision occurs.

[0040] The above-mentioned inflator 60 is arranged at the upper part of the vehicle seat 12 (here, rearward from the upper end of the seat back 16), and is oriented so that its axial direction is along the up-down direction of the seat back 16. For example, the inflator 60 is provided with a pair of upper and lower stud bolts. For example, the stud bolts pass through the frame of the seat back 16 (omitted from the illustration), and a nut is screwed on each stud bolt. Therefore, the inflator 60 is fixed to the frame of the seat back 16.

[0041] When the inflator 60 operates, the gas generated from the gas injection portion 60A provided at the upper end portion of the inflator 60 passes through the diffuser 62 and is supplied to the front and rear extension portions 34A and the propulsion chamber 39. Therefore, the front and rear extension portions 34A and the propulsion chamber 39 begin to expand and deploy. The gas supplied to the front and rear extension portions 34A and the propulsion chamber 39 flows toward the connecting portion 34B side and is supplied to the airbag body 40 through the communicating hole 48. Therefore, the airbag body 40 expands and deploys later than the front and rear chambers 34 and the propulsion chamber 39. When the airbag 32 expands and deploys, the tear line formed in the module housing and omitted from the illustration is configured to rupture under the expansion pressure of the airbag 32. This enables the airbag 32 to expand and deploy outside the module housing.

[0042] The inflated and deployed front and rear extensions 34A extend in the front-to-rear direction on both sides of the head H of the occupant D, and face the head H with a gap from both sides. The front and rear extensions 34A are pulled obliquely backward and downward by a pair of left and right rear tethers 54 to be described later, and are oriented so as to be inclined forward and downward. The front end portions of the inflated and deployed front and rear extensions 34A are in a state of being connected in the left-right direction by the inflated and deployed connecting portion 34B. Figure 3 As shown, the front and rear chambers 34 including the front and rear extension portions 34A and the connecting portion 34B are expanded and spread out in a letter U shape that opens rearward in a plan view.

[0043] like Figure 1 , Figure 2 , Figure 4 as well as Figure 5 As shown, an expansion portion 34B1 is provided at the middle portion in the left-right direction of the inflated and deployed connecting portion 34B, and the expansion portion 34B1 has a larger up-down dimension than the up-down dimension at the left and right ends of the connecting portion 34B. The expansion portion 34B1 protrudes further downward than the left and right ends of the connecting portion 34B. The aforementioned connecting hole 48 is formed in the expansion portion 34B1. The connecting hole 48 is located at the rear side of the middle portion in the left-right direction of the inflated and deployed connecting portion 34B. The gas from the inflator 60 is supplied to the airbag body 40 in the rear direction through the connecting hole 48. Therefore, at the rear of the connecting portion 34B, the airbag body 40 inflates and deploys toward the occupant D side (rear side) later than the front and rear chambers 34. The airbag body 40 is inflated and deployed through the front and rear chambers 34 , passes through a gap between the head H of the occupant D and a ceiling (omitted from illustration) of the vehicle from the rear side to the front side, and then inflates and deploys toward the rear side.

[0044] During the above-mentioned passage, the airbag body 40 is pushed to the front side by the propulsion chamber 39 that is inflated and deployed before the airbag body 40, thereby causing the airbag body 40 to expand and deploy to the front side. The inflated and deployed airbag body 40 faces the head H, chest C, and abdomen B of the occupant D from the front side with a gap. Therefore, the occupant D, who moves toward the front side under inertia due to the impact of the vehicle collision, is restrained from the front side by the inflated and deployed airbag body 40. At the time of such occupant restraint, the front and rear chambers 34 are stretched in the front-to-back direction, while the airbag body 40 is compressed in the front-to-back direction. The shape of the airbag body 40 is set to be between the thigh T and chest C of the occupant D in the middle and late stages of occupant restraint.

[0045] like Figures 1 to 6 As shown, the airbag 32 is attached with 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, the front upper tethers 56, and the front lower tethers 58 are made of, for example, nylon-based or polyester-based fabric materials in the shape of long strips. Compared with the base fabric sheets 36 and 38 constituting the front and rear chambers 34 and the base fabric sheet 42 constituting the airbag body 40, the fabric materials constituting the rear tethers 54, the front upper tethers 56, and the front lower tethers 58 are constructed to be more difficult to stretch. This more difficult to stretch characteristic can be adjusted by adjusting the material, thickness, etc. of the fabric.

[0046] Each rear tether 54 is respectively held (sewn) at an end portion on one end side to the middle portion of the front-rear extension 34A in the longitudinal direction thereof (specifically, the front portion of each front-rear extension 34A that has been inflated and deployed). The other ends of the rear tether 54 are respectively held to the seat back 16 or the vehicle body (omitted from the illustration) on the rear side of the occupant D. In a state where the airbag 32 is inflated and deployed, the rear tether 54 extends below the front-rear extension 34A in the front-rear direction. In this state, the rear tether 54 is oriented so as to be tilted downward toward the rear. Therefore, the front-rear extension 34A is configured to be pulled back tilted downward and rearward by the rear tether 54. This suppresses the airbag 32 from swinging in the up-down direction and the front-rear direction when the inflation and deployment of the airbag 32 is completed.

[0047] By such a configuration in which the front and rear extensions 34A are pulled rearward as described above, when the airbag 32 restrains the occupant D, the lower surface of the front and rear extensions 34A abuts against the left and right shoulders K of the occupant D. During the occupant restraint by the airbag 32, the airbag body 40 is supported by the tensile load of the front and rear extensions 34A and the rear tether 54. In the present embodiment, the occupant D is AM50, but even when the occupant D is AM95 (95 percent of adult males in the United States) or when the occupant D is AF05 (5 percent of adult females in the United States), the length of the rear tether 54 is set so that the lower surface of the front and rear extensions 34A will contact the left and right shoulders K of the occupant D.

[0048] The front upper tethers 56 respectively connect the left and right parts of the front part of the upper part of the airbag body 40 that is inflated and deployed on the upper side of the front and rear chambers 34 to the front part of the front and rear extensions 34A. One end of each front upper tether 56 is sewn to the left and right side parts of the front part of the upper part of the airbag body 40 that is inflated and deployed on the upper side of the front and rear chambers 34, respectively. The other ends of the front upper tethers 56 are sewn to the front part of the front and rear extensions 34A, respectively. When the inflation and deployment of the airbag 32 are completed, the front upper tethers 56 suppress the airbag body 40 from rotating upward around the connection part 34B.

[0049] The front lower tethers 58 respectively connect the left and right parts of the lower part of the airbag body 40 that expands and deploys from the front and rear chambers 34 to the front part of the front and rear extensions 34A. One end of each front lower tether 58 is sewn to the left and right side parts of the lower part of the airbag body 40 that expands and deploys on the lower side of the front and rear chambers 34. The other end of each front lower tether 58 is sewn to the front part of the front and rear extensions 34A. When the inflation and deployment of the airbag 32 is completed, the front lower tethers 58 suppress the airbag body 40 from rotating downward around the connection part 34B.

[0050] The above-mentioned airbag device 30 includes a control device (electronic control unit (ECU)) omitted from the illustration, which controls the operation of the inflator 60. The control device is electrically connected to the inflator 60 and a collision sensor omitted from the illustration. The control device can detect or predict the occurrence of various forms of frontal collisions (or the inevitability of frontal collisions) of the automobile to which it is applied for each collision form described below based on information from the collision sensor.

[0051] When a frontal collision is detected or predicted based on information from the collision sensor, the control device operates the inflator 60. Note that the forms of frontal collisions in which the control device operates the inflator 60 include not only full-wrapped frontal collisions but also offset frontal collisions such as oblique collisions, small overlap collisions, etc.

[0052] like Figure 8 and Fig. 9As shown, the diffuser 62 that distributes gas from the inflator 60 to the airbag 32 has a connection portion 62A connected to the inflator 60, and a plurality of (here, three) branch portions 62B branching from the connection portion 62A, and is configured in a four-way branch pipe form. For example, the diffuser 62 is made of a heat-resistant material such as metal. The connection portion 62A is fixed to the inflator 60 in a state where the upper end portion of the inflator 60 is fitted inside it. The three branch portions 62B extend upward from the connection portion 62A and are composed of a branch portion 62B1, a branch portion 62B2, and a branch portion 62B3. The distal end portion of the branch portion 62B1 is bent toward the front side on the upper side of the headrest 18, the branch portion 62B2 extends from the connection portion 62A to the left side, and the distal end portion thereof is bent toward the front side on the left side of the headrest 18, and the branch portion 62B3 extends from the connection portion 62A to the right side, and the distal end portion thereof is bent toward the front side on the right side of the headrest 18. The routes of these branch portions 62B1, 62B2, and 62B3 are defined so as to extend from the rear side to the front side of the headrest 18 and bypass the headrest 18.

[0053] The distal end portion of the branch portion 62B1 extending toward the upper side is inserted into a connection hole (omitted from the illustration) formed in the middle portion of the propulsion chamber 39 in its longitudinal direction. The edge portion of the connection hole in the propulsion chamber 39 is fixed to the distal end portion of the branch portion 62B1 using, for example, a metal band. The distal end portion of the branch portion 62B2 extending toward the left side is inserted into a connection hole (omitted from the illustration) formed at the rear end portion of the front-rear extension portion 34A on the left side. The edge portion of the connection hole in the front-rear extension portion 34A on the left side is fixed to the distal end portion of the branch portion 62B2 using, for example, a metal band. The distal end portion of the branch portion 62B3 extending toward the right side is inserted into a connection hole (omitted from the illustration) formed at the rear end portion of the front-rear extension portion 34A on the right side. The edge portion of the connection hole in the front-rear extension portion 34A on the right side is fixed to the distal end portion of the branch portion 62B3 using, for example, a metal band.

[0054] In the above diffuser 62, the branch portion 62B1 is communicated with the propulsion chamber 39, the branch portion 62B2 is communicated with the left front and rear extension portion 34A, and the branch portion 62B3 is communicated with the right front and rear extension portion 34A. Therefore, a configuration is formed in which the gas generated from the gas injection portion 60A of the inflator 60 is distributed to the propulsion chamber 39 and the left and right front and rear extension portions 34A through the corresponding branch portions 62B1, 62B2 and 62B3.

[0055] Inside the diffuser 62, a plurality of (here a large number of) partition walls 66 are provided. Specifically, the partition wall 66 is provided in each of the connecting portion 34B and the three branch portions 62B. A large number of partition walls 66 constitute the muffler 64. The interior of the diffuser 62 is divided into a plurality of (here a large number of) chambers 68 by a large number of partition walls 66, and the chambers 68 are interconnected. For example, each partition wall 66 is made of metal and has a truncated cone shape (similar to the shape of a disc spring) that is inclined (diameter is reduced) toward the downstream side of the flow direction F of the gas flow inside the diffuser 62. An opening (figure mark omitted) is formed in the middle portion of each partition wall 66, and the chambers 68 are interconnected through the opening of the partition wall 66. Therefore, the diffuser 62 is used as a partition wall type muffler, thereby constituting a configuration that reduces the sound pressure of the gas from the inflator 60.

[0056] Function and effect

[0057] Next, the action and effect of this embodiment will be described.

[0058] The occupant protection device 10 according to the present embodiment includes a vehicle seat 12 on which an occupant D of an automobile sits, and an airbag device 30 that protects the occupant D when a collision of the vehicle occurs. In this airbag device 30, when a collision of the vehicle occurs, gas generated by an inflator 60 installed in an upper portion of the vehicle seat 12 is guided to a diffuser 62 and distributed to the airbag 32, and the airbag 32 is inflated and deployed from the upper portion of the vehicle seat 12 toward the front side.

[0059] The diffuser 62 has a connection portion 62A connected to the inflator and a branch portion 62B branched from the connection portion 62A and connected to the airbag 32, respectively, whereby the gas is distributed to a plurality of positions of the airbag 32 through the branch portions 62B. In this diffuser 62, the connection portion 62A and the branch portion 62B are provided with a muffler 64 (a large number of partition walls 66) that reduces the sound pressure of the gas, and therefore, even when the diameters of the connection portion 62A and the branch portion 62B are respectively set small, the sound pressure of the gas is reduced in each of the connection portion 62A and the branch portion 62B, so that the muffler performance can be ensured. As a result, even in a configuration where the inflator 60 is installed near the headrest 18 close to the ears of the occupant D, the ears of the occupant D can be protected from adverse effects. In addition, the branch portions 62B, each having a smaller diameter, can be routed to fit into the space of the upper portion of the vehicle seat 12, so that the mountability at the upper portion of the vehicle seat 12 can be improved. Furthermore, the diffuser 62 that distributes the gas to a plurality of locations in the airbag 32 functions as a muffler, and therefore there is no need to perform work of fixing a dedicated muffler to the inflator 60 .

[0060] Moreover, in the present embodiment, the airbag 32 has the front and rear chambers 34, the propulsion chamber 39, and the airbag body 40. The front and rear chambers 34 include front and rear extensions 34A on the left and right sides, and the front and rear extensions 34A are expanded and deployed to the front side through the left and right sides of the head H of the occupant D sitting in the vehicle seat 12. The propulsion chamber 39 is expanded and deployed above the headrest 18, and connects the rear end portions of the front and rear extensions 34A in the left and right direction. The airbag body 40 is supplied with gas from the inflator 60 through the front and rear chambers 34, and is expanded and deployed in front of the occupant D. The branch portion 62B of the diffuser 62 is connected to the front and rear extensions 34A and the propulsion chamber 39. Therefore, it is possible to distribute the gas from the inflator 60 to each of the front and rear extensions 34A and the propulsion chamber 39, and therefore, for example, compared with a configuration in which gas is supplied from a separate inflator to each of the front and rear extensions 34A and the propulsion chamber 39, it is possible to reduce the installation space, the manufacturing cost, and the number of components.

[0061] Furthermore, in the present embodiment, the front and rear chambers 34 include a connecting portion 34B connecting the front end portions of the front and rear extension portions 34A in the left-right direction, and on the rear side of the connecting portion 34B, the airbag body 40 is inflated and deployed toward the occupant D side later than the front and rear chambers 34. When restraining the occupant D, the front and rear chambers 34 are stretched in the front and rear directions, and the airbag body 40 is compressed in the front and rear directions. Such compression deformation of the airbag body 40 can improve energy absorption performance.

[0062] Furthermore, in the present embodiment, the muffler 64 is constituted by a partition wall 66 provided inside the diffuser 62, the interior of the diffuser 62 is partitioned into a plurality of chambers 68 by the partition wall 66, and the plurality of chambers 68 are communicated with each other. Therefore, the diffuser 62 functions as a partition wall type muffler, by which the sound pressure of the gas from the inflator 60 can be effectively reduced. Moreover, since the partition wall 66 also functions as a reinforcing member for reinforcing the diffuser 62, the wall thickness of the diffuser 62 can be reduced.

[0063] In addition, each partition wall 66 has a direction along the flow direction F of the gas flowing in the diffuser 62 (see Fig.10 ) is in a truncated cone shape that is inclined toward the downstream side (the diameter decreases). Therefore, it is possible to prevent the flow of the gas flowing in the diffuser 62 from being blocked by the partition wall 66.

[0064] Note that in the above embodiment, the number of partition walls 66 , the inclination direction of the partition walls 66 , and the wall thickness of each of the diffuser 62 and the partition walls 66 are preferably adjusted in consideration of gas flow, sound pressure, strength, etc. within the diffuser 62 .

[0065] For example, like in Fig.11As in the illustrated modification, the muffler 70 may be composed of a plurality of partition walls 72 that are inclined toward the downstream side along the flow direction F of the gas flowing in the diffuser 62 and are offset from each other in the flow direction F.

[0066] Moreover, in the above embodiment and the above modification, the case where the mufflers 64 and 70 are composed of the partition walls 66 and 72 provided inside the diffuser 62 has been described, but this is not restrictive. For example, the mufflers may be glass wool, steel wool, etc. provided inside the diffuser 62.

[0067] Moreover, in the above embodiment, the airbag 32 has a configuration including the front and rear chambers 34, the propulsion chamber 39, and the airbag body 40, but the configuration of the airbag 32 is not limited thereto and can be changed as appropriate. For example, the airbag 32 can be changed to a configuration in which the airbag 32 does not have the propulsion chamber 39 but has left and right front and rear chambers 34 and the airbag body 40.

[0068] In addition, the present invention can be implemented by various modifications without departing from the spirit thereof. In addition, it goes without saying that the scope of the rights of the present invention is not limited to the above-described embodiments.

Claims

1. An airbag device, characterized in that include: an inflator which is installed in an upper portion of a vehicle seat and generates gas when a vehicle collision occurs; an airbag to which the gas is supplied and which is inflated and deployed from the upper portion of the vehicle seat toward a front side of the vehicle seat; as well as A diffuser includes a connecting portion and a plurality of branch portions, and distributes the gas to the airbag, the connecting portion is connected to the inflator, and the plurality of branch portions are respectively branched from the connecting portion and connected to the airbag, the diffuser includes a muffler at least in the plurality of branch portions, the muffler reducing the sound pressure of the gas.

2. The airbag device according to claim 1, characterized in that: The airbag comprises a front-rear chamber including a pair of extensions, wherein the pair of extensions are configured to expand and deploy toward the front side of the vehicle seat through the left and right sides of the head of an occupant seated in the vehicle seat, and the pair of extensions extend in the front-rear direction, and an airbag body to which the gas is supplied through the front and rear chambers and which expands and deploys in front of the occupant; and The plurality of branch portions of the diffuser are connected to at least the pair of extension portions.

3. The airbag device according to claim 2, characterized in that: The front-rear chamber includes a connecting portion connecting the front end portions of the pair of extension portions in the left-right direction of the vehicle seat; and The airbag body is inflated and deployed toward the passenger side later than the front-rear chambers at the rear side of the coupling portion in the front-rear direction of the vehicle seat.

4. The airbag device according to any one of claims 1 to 3, characterized in that: The muffler is a plurality of partition walls disposed inside the diffuser; and The interior of the diffuser is partitioned into a plurality of chambers by the plurality of partition walls, and the plurality of chambers are in communication with one another.

5. The airbag device according to claim 4, characterized in that: The plurality of partition walls are inclined toward a downstream side along a flow direction of the gas flowing inside the diffuser.

6. An occupant protection device, characterized in that include: a vehicle seat in which an occupant is seated; as well as The airbag device according to any one of claims 1 to 3, which is installed in an upper portion of the vehicle seat.

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