Seat-attached airbag device and method for folding airbag

Abstract

The present invention provides a seat-attached airbag device comprising an airbag that has: a pair of front-rear chambers which expand and deploy forward on the right and left sides of the head of a passenger as a result of being supplied with gas blown out from an inflator at the time of a vehicle collision; and an airbag main body which moves forward between the head of the passenger and the ceiling with the expansion and deployment of the pair of front-rear chambers, which expands and deploys rearward between the pair of front-rear chambers as a result of being supplied with gas from the pair of front-rear chambers, and which is disposed on the forward side of the passenger. The airbag has, on the rear side of the airbag main body, a pushing structure which pushes the airbag main body forward.

Description

Seat-mounted airbag device and airbag folding method

[0001] The present disclosure relates to a seat-mounted airbag device and an airbag folding method.

[0002] For example, as disclosed in Japanese Patent Application Laid-Open No. 2019-218013, airbag devices equipped with an airbag having a rear inflatable portion that deploys on the back side of the seat, a pair of side inflatable portions that extend forward from both the left and right sides of the rear inflatable portion, and a pair of front inflatable portions that extend from the side inflatable portions to the center and are connected to each other at the center to cover the front of the occupant have been known for some time.

[0003] Furthermore, as disclosed in Japanese Patent Application Laid-Open No. 2019-018593, for example, an airbag device is also known that includes a bag body having a trunk support portion that deploys from behind the occupant's head to in front of the occupant, and a pair of head support portions that deploy on both the left and right sides of the occupant's head and are connected to the trunk support portion. This bag body has a recess that, when deployed, penetrates vertically between the pair of head support portions to avoid the occupant's head.

[0004] In the airbag device described above, the airbag body is inflated and deployed while passing through the gap between the occupant's head and the ceiling from the seat back, and is positioned in front of the occupant. Therefore, it is desirable that the airbag body remain small and not allow gas to flow in until it passes over the occupant's head, and then allow gas to flow in and inflate after it has passed over the occupant's head.

[0005] However, when gas is introduced into the airbag body to inflate the airbag body after the airbag has passed over the occupant's head, it tends to take a long time for the airbag body to fully inflate and deploy. As such, there is still room for improvement in terms of both improving the airbag body's deployment performance in the gap between the occupant's head and the ceiling and speeding up the completion of inflation and deployment of the airbag body.

[0006] Therefore, the present disclosure provides a seat-mounted airbag device that can improve the deployment performance of the airbag body located in front of the occupant's seat by inflating and deploying through the gap between the occupant's head and the ceiling of the vehicle compartment, while also speeding up the time until inflation and deployment is completed, and a method for folding the airbag.

[0007] A seat-mounted airbag device of a first aspect according to the present disclosure comprises an airbag that is mounted on a vehicle seat and that ejects gas in the event of a vehicle collision; a pair of front and rear chambers that, when supplied with gas ejected from the inflator, inflate and deploy toward the front of the seat by passing through both sides of the head of an occupant seated in the vehicle seat; and an airbag body that, as the pair of front and rear chambers inflate and deploy, moves toward the front of the seat by passing between the occupant's head and the ceiling of the vehicle compartment and, as the gas is supplied from the pair of front and rear chambers, inflates and deploys toward the rear of the seat between the pair of front and rear chambers, and is positioned in front of the occupant's seat, wherein the airbag is mounted on the seat rear side of the airbag body and has an extrusion structure that extrudes the airbag body toward the front of the seat.

[0008] According to the first aspect, in the event of a vehicle collision, gas ejected from the inflator is supplied to the pair of front and rear chambers, which inflate and deploy toward the front of the seat by passing over both sides of the head of an occupant seated in the vehicle seat. As the pair of front and rear chambers inflate and deploy, the airbag body passes between the head of the occupant seated in the vehicle seat and the ceiling of the vehicle compartment and moves toward the front of the seat. At the same time, as gas is supplied from the pair of front and rear chambers, the airbag body inflates and deploys toward the rear of the seat between the pair of front and rear chambers and is positioned in front of the seat. In other words, the airbag body inflates and deploys with a delay relative to the pair of front and rear chambers, ensuring reliable movement between the occupant's head and the ceiling of the vehicle compartment.

[0009] The airbag also has a push-out structure on the rear side of the airbag body that pushes the airbag body toward the front of the seat. Therefore, the airbag body is forcibly pushed toward the front of the seat from its initial position (installed position) by the push-out structure. This shortens the time the airbag body remains in its initial position during a vehicle collision, shortening the time until the airbag body is fully inflated and deployed.

[0010] In other words, according to the present disclosure, the airbag body disposed in front of the seat of the occupant is inflated and deployed through the gap between the occupant's head and the ceiling of the vehicle compartment, thereby improving the deployment performance and accelerating the completion of inflation and deployment. Note that "at the time of a collision" as used here also includes when the inevitability of a collision is predicted (foreseen).

[0011] A seat-mounted airbag device of a second aspect according to the present disclosure is the seat-mounted airbag device of the first aspect, wherein the extrusion structure is configured with an extrusion chamber that interconnects the pair of front and rear chambers.

[0012] According to the second aspect, the pushing structure is configured with a pushing chamber that connects the pair of front and rear chambers to each other, so that the airbag body is reliably pushed out from the initial position (mounted position) toward the front of the seat by the pushing chamber.

[0013] A seat-mounted airbag device of a third aspect according to the present disclosure is the seat-mounted airbag device of the first aspect, wherein the extrusion structure is configured by an extrusion chamber separate from the pair of front and rear chambers.

[0014] According to the third aspect, the pushing structure is configured with a push-out chamber separate from the pair of front and rear chambers. Therefore, the airbag body is reliably pushed out from the initial position (mounted position) toward the front of the seat by the push-out chamber. Furthermore, because the push-out chamber is configured separate from the pair of front and rear chambers, the configuration of the airbag is simplified.

[0015] A seat-mounted airbag device of a fourth aspect according to the present disclosure is the seat-mounted airbag device of the first aspect, wherein the extruded structure is formed of an extruded fabric that interconnects the pair of front and rear chambers.

[0016] According to the fourth aspect, the extrusion structure is formed of an extrusion cloth that interconnects the pair of front and rear chambers. Therefore, when the pair of front and rear chambers move toward the front of the seat, tension is applied to the extrusion cloth in the seat width direction. Therefore, the airbag body is reliably pushed toward the front of the seat from its initial position (installed position) by the extrusion cloth. Furthermore, because the extrusion structure is formed of an extrusion cloth, the airbag can be stored compactly and is lightweight.

[0017] Furthermore, a seat-mounted airbag device of a fifth aspect according to the present disclosure is the seat-mounted airbag device of the second or third aspect, in which a single inflator is provided, and the vehicle seat is provided with distribution pipes that can supply gas ejected from the inflator to the pair of front and rear chambers and the extrusion chamber, respectively, and the inner diameter of the outlet of the distribution pipe connected to the base portions of the pair of front and rear chambers is larger than the inner diameter of the outlet of the distribution pipe connected to the base portion of the extrusion chamber.

[0018] According to the fifth aspect, a single inflator is provided, and gas ejected from the inflator is supplied to the pair of front and rear chambers and the extrusion chamber by distribution pipes, respectively. Therefore, compared to a case where one or two inflators are provided for the pair of front and rear chambers and one is provided for the extrusion chamber, the number of parts and installation space are reduced, and manufacturing costs are reduced.

[0019] Furthermore, the inner diameter of the outlet of the distribution pipe connected to the base of the pair of front and rear chambers is larger than the inner diameter of the outlet of the distribution pipe connected to the base of the extrusion chamber, so the amount of gas supplied to the pair of front and rear chambers is greater than the amount of gas supplied to the extrusion chamber, and this enables the airbag body to complete inflation and deployment more quickly.

[0020] Furthermore, a seat-mounted airbag device of a sixth aspect according to the present disclosure is the seat-mounted airbag device of the fifth aspect, wherein the headrest of the vehicle seat is formed integrally with the seat back of the vehicle seat, and the inflator is arranged along the extension direction of the seat back.

[0021] According to the sixth aspect, the headrest is integrally formed with the seat back. Therefore, the airbag is more likely to be prevented from being detached from the vehicle seat than when the headrest is separate from the seat back. Furthermore, the inflator is disposed along the extension direction of the seat back. Therefore, the headrest and the seat back do not need to be enlarged (thicker) than when the inflator is disposed along a direction intersecting the extension direction of the seat back.

[0022] Furthermore, a seat-mounted airbag device of a seventh aspect according to the present disclosure is the seat-mounted airbag device of the second or third aspect, wherein the two inflators are provided: a first inflator that supplies gas to the pair of front and rear chambers, and a second inflator that supplies gas to the extrusion chamber; and the vehicle seat is provided with a first distribution pipe that can supply gas ejected from the first inflator to the pair of front and rear chambers, and a second distribution pipe that can supply gas ejected from the second inflator to the extrusion chamber, and the inner diameter of the outlet of the first distribution pipe connected to the base of the pair of front and rear chambers is larger than the inner diameter of the outlet of the second distribution pipe connected to the base of the extrusion chamber.

[0023] According to the seventh aspect, two inflators are provided: a first inflator that supplies gas to the pair of front and rear chambers, and a second inflator that supplies gas to the extrusion chamber, and gas ejected from the first inflator is supplied to the pair of front and rear chambers by a first distribution pipe, and gas ejected from the second inflator is supplied to the extrusion chamber by a second distribution pipe. Therefore, compared to a case where two inflators are provided for the pair of front and rear chambers and one inflator is provided for the extrusion chamber, the number of parts and mounting space are reduced, and manufacturing costs are reduced.

[0024] Furthermore, the inner diameter of the outlet of the first distribution pipe connected to the base of the pair of front and rear chambers is larger than the inner diameter of the outlet of the second distribution pipe connected to the base of the extrusion chamber, so that the amount of gas supplied to the pair of front and rear chambers is greater than the amount of gas supplied to the extrusion chamber, thereby accelerating the completion of inflation and deployment of the airbag body.

[0025] Furthermore, an eighth aspect of the seat-mounted airbag device according to the present disclosure is the seat-mounted airbag device of the seventh aspect, wherein the headrest of the vehicle seat is formed integrally with the seat back of the vehicle seat, and the first inflator and the second inflator are arranged along the extension direction of the seat back.

[0026] According to the eighth aspect, the headrest is formed integrally with the seat back. Therefore, the airbag is more likely to be prevented from becoming detached from the vehicle seat than when the headrest is separate from the seat back. Furthermore, the first inflator and the second inflator are arranged along the extension direction of the seat back. Therefore, the headrest and the seat back can be prevented from becoming larger (thicker) than when the first inflator and the second inflator are arranged along a direction intersecting the extension direction of the seat back.

[0027] Furthermore, a seat-mounted airbag device of a ninth aspect according to the present disclosure is the seat-mounted airbag device of the second or third aspect, wherein three inflators are provided so as to be able to supply gas to the pair of front and rear chambers and the extrusion chamber, respectively, and the output of the two inflators that supply gas to the pair of front and rear chambers, respectively, is higher than the output of the single inflator that supplies gas to the extrusion chamber.

[0028] According to the ninth aspect, three inflators are provided so as to be capable of supplying gas to the pair of front and rear chambers and the extrusion chamber, respectively, and the outputs of the two inflators supplying gas to the pair of front and rear chambers respectively are set to be higher than the output of the one inflator supplying gas to the extrusion chamber. Therefore, the amount of gas supplied to the pair of front and rear chambers is greater than the amount of gas supplied to the extrusion chamber, and the airbag main body can be quickly inflated and deployed.

[0029] Furthermore, a seat-mounted airbag device of a tenth aspect according to the present disclosure is the seat-mounted airbag device of any one of the first to ninth aspects, in which a valve mechanism is provided at the tip end of the pair of front and rear chambers to instantaneously block the inflow of the gas.

[0030] According to the tenth aspect, a valve mechanism that momentarily blocks the inflow of gas is provided at the tip of the pair of front and rear chambers. This makes it possible to control the gas flow so that it does not flow into the airbag body until it passes between the occupant's head and the ceiling of the vehicle compartment and moves toward the front of the seat. Therefore, the airbag body can reliably move toward the front of the seat, which results in the airbag body completing inflation and deployment more quickly.

[0031] An eleventh aspect of the airbag folding method according to the present disclosure is a method for folding an airbag having a pair of front and rear chambers that are supplied with gas ejected from an inflator provided in a vehicle seat in the event of a vehicle collision, and that inflate and deploy toward the front of the seat, passing through both the left and right sides of the head of an occupant seated in the vehicle seat; and an airbag body that moves toward the front of the seat through between the occupant's head and the ceiling of the vehicle compartment as the pair of front and rear chambers inflate and deploy toward the rear of the seat between the pair of front and rear chambers, and is positioned in front of the occupant's seat, and includes providing the airbag made of a base fabric in a flat shape, and pulling out a portion of the base fabric to the outside of the airbag in the seat width direction.

[0032] According to the eleventh aspect, when the airbag is folded, the airbag is provided in a flat shape and a portion of the base fabric is pulled outward in the seat width direction. Therefore, the thickness of the airbag due to overlapping base fabrics is reduced, and the thickness of the airbag is reduced, improving the deployment performance of the airbag that moves toward the front of the seat through the gap between the occupant's head and the ceiling of the vehicle compartment. In other words, the airbag can reliably move toward the front of the seat, resulting in earlier completion of inflation and deployment of the airbag.

[0033] Furthermore, the airbag folding method of a twelfth aspect according to the present disclosure is the airbag folding method of the eleventh aspect, further comprising: a roll folding process for rolling-folding the tip portions of the pair of front and rear chambers from the front side of the seat toward the upper side of the seat a predetermined number of times; and an accordion folding process for accordion-folding the pair of front and rear chambers excluding the tip portions a plurality of times.

[0034] According to the twelfth aspect, the leading ends of the pair of front and rear chambers are folded in a roll shape from the front side of the sheet toward the upper side of the sheet a predetermined number of times, and the pair of front and rear chambers excluding the leading ends are folded in an accordion shape a plurality of times.

[0035] It is known that accordion-shaped folding allows for faster deployment than roll-shaped folding. Therefore, the pair of front and rear chambers, except for their distal ends, are inflated and deployed early. Furthermore, the distal ends of the pair of front and rear chambers are controlled so as not to inflate and deploy until the airbag body passes between the occupant's head and the ceiling of the vehicle cabin and moves toward the front of the seat. This allows the airbag body to reliably move toward the front of the seat, ultimately resulting in earlier completion of inflation and deployment of the airbag body.

[0036] In addition, the airbag folding method of a thirteenth aspect according to the present disclosure is the airbag folding method of the twelfth aspect, in which the number of roll foldings is one.

[0037] According to a thirteenth aspect, the distal ends of the pair of front and rear chambers are folded once. If the number of folding times is, for example, 0.5, gas begins to flow into the airbag body before the airbag body passes between the occupant's head and the passenger compartment ceiling and moves toward the front of the seat. Therefore, the airbag body is less likely to move toward the front of the seat through the gap between the occupant's head and the passenger compartment ceiling. On the other hand, if the number of folding times is, for example, 1.5, the flow of gas from the distal ends of the pair of front and rear chambers into the airbag body after the airbag body has moved toward the front of the seat is slower, so inflation and deployment of the airbag body toward the rear of the seat is slower.

[0038] In contrast, because the airbag is folded once, gas does not begin to flow into the airbag before the airbag passes between the occupant's head and the passenger compartment ceiling and moves toward the front of the seat. This makes it easier for the airbag to move toward the front of the seat through the gap between the occupant's head and the passenger compartment ceiling. Furthermore, after the airbag has moved toward the front of the seat, gas flows into the airbag from the tips of the pair of front and rear chambers more quickly, which speeds up the airbag's inflation and deployment toward the rear of the seat. This allows the airbag to complete inflation and deployment more quickly.

[0039] In addition, the airbag folding method of a fourteenth aspect according to the present disclosure is the airbag folding method of the twelfth or thirteenth aspect, wherein the number of accordion folds is three.

[0040] According to the fourteenth aspect, the pair of front and rear chambers are folded accordion-like three times. Therefore, the pair of front and rear chambers, except for their tip ends, are inflated and deployed earlier than when the pair of front and rear chambers are folded accordion-like four or more times.

[0041] An airbag folding method of a fifteenth aspect according to the present disclosure is the airbag folding method of the eleventh aspect, wherein pulling out a portion of the base fabric constituting the airbag to the outside of the airbag in the seat width direction includes pulling out the base fabric on both the left and right sides that has entered the inside of the airbag body to the outside of the airbag body in the seat width direction.

[0042] According to the fifteenth aspect, when the airbag body is folded, the airbag body is provided in a flattened shape, and the base fabric on both the left and right sides that is tucked inside the airbag body is pulled outward from the airbag body in the seat width direction. This reduces the thickness of the airbag body due to overlapping base fabrics, thereby reducing the thickness of the airbag body, thereby improving the deployment performance of the airbag body that moves toward the front of the seat through the gap between the occupant's head and the ceiling of the vehicle cabin. In other words, the airbag body can reliably move toward the front of the seat, which ultimately shortens the time until the airbag body is fully inflated and deployed.

[0043] An airbag folding method of a sixteenth aspect according to the present disclosure is the airbag folding method of the eleventh aspect, wherein pulling a portion of the base fabric constituting the airbag outward from the airbag in the seat width direction includes pulling approximately central portions in the up-down direction of the base fabric on both the left and right sides of the front and rear chambers outward from the front and rear chambers in the seat width direction.

[0044] According to the sixteenth aspect, when the front and rear chambers are folded, the front and rear chambers are provided in a flattened state, and the approximately central portions of the base fabrics on both the left and right sides of the front and rear chambers are pulled outward in the seat width direction from the front and rear chambers. This reduces the thickness of the base fabrics of the front and rear chambers due to their overlapping, and therefore the thickness of the front and rear chambers themselves, making them easier to fold and allowing them to be folded compactly.

[0045] As described above, according to the present disclosure, it is possible to improve the deployment performance of the airbag body located in front of the occupant's seat and complete inflation and deployment more quickly by inflating and deploying through the gap between the occupant's head and the ceiling of the vehicle compartment.

[0046] 4 is a schematic perspective view showing a state in which the airbag of the seat-mounted airbag device according to the first embodiment is inflated and deployed; FIG. 5 is a schematic side view showing a state in which the airbag of the seat-mounted airbag device according to the first embodiment is inflated and deployed; FIG. 6 is a schematic plan view showing a state in which the airbag of the seat-mounted airbag device according to the first embodiment is inflated and deployed; FIG. 7 is a schematic plan view showing a shape of the airbag according to the first embodiment before folding; FIG. 8 is a schematic enlarged cross-sectional view taken along the arrows X-X in FIG. 4; FIG. 9 is a schematic enlarged cross-sectional view taken along the arrows Y-Y in FIG. 4; FIG. 10 is a schematic plan view showing a folding process of the airbag according to the first embodiment; FIG. 11 is a schematic plan view showing a folding process of the airbag according to the first embodiment; FIG. 12 is a schematic plan view showing a folding process of the airbag according to the first embodiment; FIG. 13 is a schematic plan view showing a folding process of the airbag according to the first embodiment; FIG. 14 is a schematic plan view showing a folding process of the airbag according to the first embodiment; FIG. 15 is a schematic plan view showing a shape of the airbag according to the first embodiment after folding; FIG. 16 is a schematic front view showing, partially in cross section, the airbag stored in the headrest according to the first embodiment. 1 is a schematic front view showing the shape of a distribution pipe in a first embodiment, with the airbag omitted in partial cross section. FIG. 2 is a schematic side view showing the airbag stored in a headrest in the first embodiment, with the airbag omitted in partial cross section. FIG. 3 is a schematic plan view showing the process of an initial stage of inflation and deployment of an airbag in the first embodiment. FIG. 4 is a schematic plan view showing the process of an initial stage of inflation and deployment of an airbag in the first embodiment. FIG. 5 is a schematic side view showing the process of an initial stage of inflation and deployment of an airbag in the first embodiment. FIG. 6 is a schematic side view showing the process of an intermediate stage of inflation and deployment of an airbag in the first embodiment. FIG. 7 is a schematic side view showing the process of a later stage of inflation and deployment of an airbag in the first embodiment. FIG. 8 is a schematic plan view showing the process of an initial stage of inflation and deployment of an airbag in a second embodiment. FIG. 9 is a schematic plan view showing the process of an initial stage of inflation and deployment of an airbag in the second embodiment. FIG. 10 is a schematic front view showing the shape of a distribution pipe in a third embodiment, with the airbag omitted in partial cross section.18 is a schematic side view, partially in cross section, of an airbag stored in a headrest according to a third embodiment. FIG. 19 is a schematic plan view showing the initial stage of inflation and deployment of an airbag according to a fourth embodiment. FIG. 19 is a schematic plan view showing the initial stage of inflation and deployment of an airbag according to a fourth embodiment. FIG. 19 is a schematic plan view showing the initial stage of inflation and deployment of an airbag according to a fourth embodiment. FIG. 19 is a schematic plan view showing the initial stage of inflation and deployment of an airbag according to a fourth embodiment. FIG. 19 is a schematic plan view showing the initial stage of inflation and deployment of an airbag according to a fifth embodiment. FIG. 19 is a schematic plan view showing the initial stage of inflation and deployment of an airbag according to a fifth embodiment. FIG. 19 is a schematic plan view showing the initial stage of inflation and deployment of an airbag according to a fifth embodiment. FIG. 19 is a schematic plan view showing the initial stage of inflation and deployment of an airbag according to a fifth embodiment.

[0047] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. For ease of explanation, the arrow UP shown in each drawing indicates the upward direction of the vehicle and vehicle seat, the arrow FR indicates the forward direction of the vehicle and vehicle seat, the arrow RH indicates the rightward direction of the vehicle and vehicle seat, and the arrow LH indicates the leftward direction of the vehicle and vehicle seat. Therefore, in the following description, unless otherwise specified, when the directions of up / down, front / rear, and left / right are mentioned, they refer to up / down, front / rear, and left / right of the vehicle and vehicle seat. Furthermore, the left / right direction is synonymous with the vehicle width direction and the seat width direction.

[0048] First Embodiment First, a seat-mounted airbag device (hereinafter simply referred to as "airbag device") 30 according to a first embodiment will be described. As shown in FIG. 1, an occupant protection device 10 is configured with a vehicle seat 12 and an airbag device 30. The vehicle seat 12 is a front seat or a rear seat of a vehicle (automobile). Here, the vehicle seat 12 is a rear seat, not a front seat 13 (see FIGS. 11 to 13).

[0049] 1 to 3 also show a crash test dummy (human dummy) seated in a vehicle seat 12 as a model of the occupant (seat occupant) to be protected. The dummy is, for example, a frontal crash test dummy (Hybrid III) AM50 (50th percentile of American adult males). The dummy is seated in a standard seating position defined by the crash test method, and the vehicle seat 12 is positioned in a reference setting position corresponding to the seating position. Hereinafter, the dummy will be referred to as "occupant D."

[0050] The vehicle seat 12 includes a seat cushion 14 on which an occupant D sits (supporting the buttocks and thighs F of the occupant D), and a seat back 16 that extends upwardly behind the seat cushion 14 in a side view seen from the seat width direction and is rotatable about the seat width direction as an axial direction, supporting the back of the occupant D. The seat back 16 has a headrest 18 integrally formed at its upper end in the center in the seat width direction, for supporting the head H of the occupant D. The rear wall of the headrest 18 is formed by a backboard 19 (see FIG. 9B ).

[0051] 1 to 3, an occupant D seated on a seat cushion 14 of a vehicle seat 12 is restrained in the vehicle seat 12 by a seat belt 22 provided in a seat belt device 20. The seat belt device 20 is a three-point seat belt device, and is a so-called seat-mounted seat belt device in which a retractor and anchor, not shown, and a buckle are each provided on the vehicle seat 12.

[0052] The airbag device 30 includes an airbag 32 and a single inflator 44 (see FIG. 9). The airbag 32 is normally stored in a folded state inside the headrest 18 (see FIGS. 8, 9B, and 10A). The inflator 44 is, for example, a combustion-type or cold gas-type inflator formed into a substantially cylindrical shape, and is provided along the extension direction of the seatback 16 (with its axial direction facing up and down) inside the seatback 16 or spanning from the inside of the seatback 16 to the inside of the headrest 18.

[0053] The airbag device 30 also includes a control device (ECU), not shown, that controls the activation of the inflator 44. The control device is electrically connected to the inflator 44 and a collision sensor (including a camera, etc.), not shown, and is configured to detect a frontal collision of the vehicle or predict the inevitability of a frontal collision. The control device activates the inflator 44 when it detects or predicts a frontal collision of the vehicle based on information from the collision sensor.

[0054] That is, when a frontal collision of the vehicle is detected or predicted (hereinafter sometimes referred to as "at the time of a frontal collision of the vehicle"), the inflator 44 is activated by the control device to generate gas and eject it from the ejection port 44A (see FIG. 9). Note that the types of frontal collisions of the vehicle for which the control device activates the inflator 44 include not only full-overlap frontal collisions but also offset frontal collisions such as oblique collisions and slight-overlap collisions.

[0055] The airbag 32 is deployed and inflated forward by gas ejected from the inflator 44, passing from the front of the headrest 18 to both sides of the head H of the occupant D seated in the vehicle seat 12 and above the head H of the occupant D. More specifically, the airbag 32 has a pair of front and rear chambers 34 and an airbag body 40.

[0056] 4, the pair of front and rear chambers 34 include a pair of left and right front and rear extending portions 34A that, when supplied with gas ejected from the inflator 44, inflate and deploy forward and extend in the front-to-rear direction by passing through both the left and right sides of the head H of the occupant D, a front connecting portion 34B (see FIGS. 1 to 3) that connects the front ends of the pair of front and rear extending portions 34A in the left-to-right direction, and a rear connecting portion 34C that connects (connects to each other) the rear ends of the pair of front and rear extending portions 34A in the left-to-right direction. Note that this rear connecting portion 34C is the "extrusion chamber" and is disposed on the rear side of the airbag body 40.

[0057] The front connecting portion 34B is formed in a bag shape that is generally T-shaped in a front view and is continuous with the pair of front-rear extending portions 34A (see FIGS. 1 to 3). In addition, cylindrical root portions 36 that extend rearward are formed integrally with the rear ends of the pair of front-rear chambers 34 (front-rear extending portions 34A), in other words, with both end portions in the seat width direction on the rear surface of the rear connecting portion 34C, and a cylindrical root portion 38 that extends rearward is also formed integrally with the center portion in the seat width direction on the rear surface of the rear connecting portion 34C.

[0058] In the following description, the left root portion 36 may be referred to as the "root portion 36L," and the right root portion 36 may be referred to as the "root portion 36R." The left and right root portions 36 and the central root portion 38 are connected to respective outlets 46A, 48A of branch pipes 46, 48 of a distribution pipe (diffuser) 50, which will be described later. The front and rear chambers 34 are formed into a long bag (tube) shape by overlapping two long pieces of base fabric and sewing together the upper and lower peripheral edges (see FIG. 5B ).

[0059] As the pair of front and rear chambers 34 (front and rear extension portions 34A) inflate and deploy, the airbag main body 40 moves forward between the head H of the occupant D and the ceiling 28 of the vehicle compartment (see Figures 11 to 13), and then, as gas is supplied from the pair of front and rear chambers 34, it inflates and deploys toward the occupant D (rearward) behind the pair of front and rear chambers 34, behind the front connecting portion 34B, and is positioned between the pair of front and rear chambers 34 (front and rear extension portions 34A) and in front of the occupant D.

[0060] The airbag body 40 is formed into a bag shape by folding a single piece of base fabric that has been die-cut into a predetermined shape and sewing its peripheral edges (see FIG. 5A ). The front connecting portion 34B of the front and rear chambers 34 has a communication hole (not shown) formed in the rear surface of the center portion in the left-right direction of the base fabric, and the airbag body 40 is connected to the front and rear chambers 34 by sewing the periphery of the communication hole (not shown) formed in the base fabric. The base fabrics of the front and rear chambers 34 and the airbag body 40 are each made of, for example, a polyamide-based or polyester-based fabric material.

[0061] Here, a method for folding the airbag 32 will be described. As shown in Figures 4 and 5A, the airbag 32 is first prepared by providing the airbag body 40 and the front and rear chambers 34, each of which is sewn from a base fabric, in a flat state (providing step). Next, before the airbag body 40 is folded (wound) into a roll, the base fabrics 40A on both the left and right sides of the airbag body 40, which are inserted inside the airbag body 40 in the seat width direction, are pulled outward from the airbag body 40 in the seat width direction and crushed substantially flat (extracting step of the airbag body 40). Then, as shown in Figures 4 and 5B, before the pair of front and rear chambers 34 are folded into an accordion-like shape, approximately central portions of the base fabrics 34D in the up-down direction are pulled outward from the front and rear chambers 34 in the seat width direction and crushed substantially flat (extracting step of the front and rear chambers 34).

[0062] In this state, the airbag 32 is folded as shown in Fig. 6. First, as shown in Figs. 6A to 6C, the airbag body 40 is rolled up from the front side to the upper side. In other words, the airbag body 40 is folded up into an outwardly wound roll so that it can be easily unwound by the inertial force that accompanies forward movement. Then, the tip ends 34F of the pair of front and rear chambers 34 (front and rear extensions 34A) are rolled up once from the front side to the upper side (outwardly wound roll-folded: roll-folding process).

[0063] Next, as shown in Figures 6D to 6F, the pair of front and rear chambers 34 (front and rear extensions 34A) are folded accordion-like (accordion folding process), excluding the rolled tip end 34F. The pair of front and rear chambers 34 (front and rear extensions 34A) excluding the tip end 34F are folded accordion-like, forming only three peaks. In other words, the accordion folding is performed three times. Also, Figure 6F shows the state in which the branch pipes 46, 48 of the distribution pipe 50, which will be described later, are connected.

[0064] The folded state is shown in Figure 7, and the boundary 42 (see Figures 7 and 8) between the airbag body 40 folded into a roll and the rolled-up tip ends 34F of the pair of front and rear chambers 34 forms a fold line, allowing the pair of front and rear chambers 34 to be folded downward.

[0065] 8, the airbag 32 in this state is accommodated inside the headrest 18. In other words, the airbag 32 is configured to be arranged along the outer shape (top surface and both left and right side surfaces) of the headrest 18 when viewed from the front, and the position where it is accommodated in this state is the initial position (installed position) of the airbag 32.

[0066] A tear line (not shown) is formed on the front surface of the headrest 18. This tear line is configured to tear when subjected to the inflation pressure of the airbag 32 when the airbag 32 is inflated and deployed. This allows the airbag 32 to inflate and deploy from the front surface of the headrest 18 forward, in the order of the pair of front and rear chambers 34 and the airbag body 40.

[0067] 9A , a resin or metal distribution pipe 50 is disposed inside the headrest 18 at the rear side. The distribution pipe 50 branches in three directions, with cylindrical branch pipes 46 branching to the left and right from a center portion in the seat width direction, and a cylindrical branch pipe 48 branching upward from the center portion in the seat width direction. In the following description, the branch pipe 46 branching to the left from the center portion in the seat width direction of the distribution pipe 50 may be referred to as the "branch pipe 46L," and the branch pipe 46 branching to the right from the center portion in the seat width direction of the distribution pipe 50 may be referred to as the "branch pipe 46R."

[0068] As shown in Figure 9B, the outlet 46A of the left branch pipe 46L and the outlet 46A of the right branch pipe 46R each extend forward and upward at a predetermined angle (e.g., 20° to 30° from the horizontal) and a predetermined length when viewed from the side, and the outlet 48A of the upper branch pipe 48 also extends forward and upward at a predetermined angle (e.g., 20° to 30° from the horizontal) and a predetermined length when viewed from the side.

[0069] It should be noted that the "predetermined length" of the outlets 46A and 48A is preferably set to, for example, 30 mm to 40 mm. If the length of the outlets 46A and 48A is shorter than 30 mm, there is a risk that the gas will not be ejected in the intended direction, and if it is longer than 40 mm, the thickness of the headrest 18 will be increased unnecessarily.

[0070] 10 , the outlet 46A of the left branch pipe 46L and the outlet 46A of the right branch pipe 46R also extend outward and forward in the seat width direction at a predetermined angle (e.g., 10° to 20° with respect to the front-to-rear direction) in a plan view. As a result, the pair of front and rear chambers 34 inflate and deploy outward and forward in the seat width direction, so that the rolled airbag body 40 moves from the rear side to the front side while being pulled outward in the seat width direction.

[0071] 4, 6F, and 10, the outlet 46A of the left branch pipe 46L and the outlet 46A of the right branch pipe 46R are connected to the left root portion 36L and the right root portion 36R of the rear connecting portion 34C, respectively, and the outlet 48A of the upper branch pipe 48 is connected to the central root portion 38 of the rear connecting portion 34C. Note that, as shown in Fig. 9B, in the airbag 32 accommodated inside the headrest 18, the left and right root portions 36L, 36R (only the left root portion 36L is shown in Fig. 9B) are located in approximately the center in the up-down direction on the rear side of the pair of front and rear chambers 34.

[0072] In other words, in a side view, the outlet 46A of the left branch pipe 46L and the outlet 46A of the right branch pipe 46R (only the left branch pipe 46L is shown in FIG. 9B ) are each located approximately in the vertical center on the rear side of the pair of front and rear chambers 34. Furthermore, as shown in FIG. 9A , the inner diameters of the outlet 46A of the left branch pipe 46L and the outlet 46A of the right branch pipe 46R are the same and are larger (for example, about 1.2 times larger) than the inner diameter of the outlet 48A of the upper branch pipe 48.

[0073] An outlet 44A of the inflator 44 is connected to a cylindrical base 52 extending downward from the center of the distribution pipe 50 in the seat width direction. In other words, the inflator 44 is configured to inject gas into the left branch pipe 46L and the right branch pipe 46R of the distribution pipe 50, which can supply gas respectively to the pair of front and rear chambers 34, and is also configured to inject gas into the upper branch pipe 48 of the distribution pipe 50, which can supply gas to the center of the rear connecting portion 34C.

[0074] 10B and 10C, the rolled-up airbag body 40 is pushed forward by the inflated rear connecting portion 34C. In other words, the airbag body 40 is not only moved forward from its initial position by the inflation and deployment of the pair of front and rear chambers 34, but is also forcibly pushed forward by the inflated rear connecting portion 34C. In this way, the rear connecting portion 34C is a pushing chamber that assists in pushing the airbag body 40 forward, and constitutes a pushing structure.

[0075] 1 to 3 , in the airbag device 30 configured as described above, the front-rear extending portions 34A of the pair of inflated and deployed front-rear chambers 34 extend in the front-rear direction on both the left and right sides of the head H of the occupant D, facing each other with a gap between them on both the left and right sides of the head H. The front ends of the pair of inflated and deployed front-rear extending portions 34A are connected in the left-right direction by the inflated and deployed front connecting portion 34B. As a result, the front-rear chambers 34, including the pair of front-rear extending portions 34A and the front connecting portion 34B protruding from the headrest 18, are configured to have a substantially U-shape that opens rearward in a plan view (see FIG. 3 ).

[0076] 11 to 13, the airbag body 40 moves forward as the pair of front and rear chambers 34 inflate and deploy, and then inflates and deploys rearward (toward the occupant D) as gas is supplied from the front and rear chambers 34. In other words, when the pair of front and rear chambers 34 inflate and deploy, the airbag body 40, while remaining folded into a roll, passes from the rearward to the frontward through the narrow gap between the head H of the occupant D and the ceiling 28 of the vehicle compartment (as shown by the imaginary line and arrow A in FIG. 11).

[0077] The airbag body 40 is configured to inflate and deploy toward the occupant D (rearward) behind the pair of front and rear chambers 34, rearward of the front connecting portion 34B, and the inflated and deployed airbag body 40 faces the head H, chest C, and abdomen B of the occupant D with gaps in the front-to-rear direction (see FIGS. 1 to 3). The shape of the airbag body 40 when inflated and deployed is set so that it is sandwiched between the thighs F and chest C of the occupant D from the middle to late stages of occupant restraint.

[0078] 1 to 3, 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 are attached to the airbag 32. The rear tethers 54, the front upper tethers 56, and the front lower tethers 58 are formed in the shape of long strips from, for example, a polyamide-based or polyester-based fabric material. The fabric materials forming the rear tethers 54, the front upper tethers 56, and the front lower tethers 58 are configured to be less stretchable than the base fabric forming the front and rear chambers 34. This resistance to stretch is adjusted by the material and thickness of the fabric.

[0079] The pair of front upper tethers 56 are configured to connect the left and right wall surfaces on the front side of an upper portion of the airbag body 40 that inflates and deploys above the front and rear chambers 34 to the front portions of the pair of front and rear extending portions 34A. That is, one end of each of the pair of front upper tethers 56 is sewn to the left and right wall surfaces on the front side of the upper portion of the airbag body 40 that inflates and deploys above the front and rear chambers 34. The other end of each of the pair of front upper tethers 56 is sewn to the front portions of the pair of front and rear extending portions 34A.

[0080] The pair of front lower tethers 58 are configured to connect the left and right wall surfaces on the front side of the lower portion of the airbag body 40 that inflates and deploys downward from the front and rear chambers 34 to the front portions of the pair of front and rear extending portions 34A. That is, one end of each of the pair of front lower tethers 58 is sewn to the left and right wall surfaces on the front side of the lower portion of the airbag body 40 that inflates and deploys downward from the front and rear chambers 34. The other end of each of the pair of front lower tethers 58 is sewn to the front portions of the pair of front and rear extending portions 34A.

[0081] Meanwhile, one end of each of the pair of rear tethers 54 is attached by sewing to the underside of the front portion of the front and rear chamber 34 (front and rear extending portions 34A) that faces in the seat width direction approximately the center of the inflated and deployed airbag body 40 in a side view. The other end of each of the pair of rear tethers 54 is attached to the side of the seat back 16 (or to the vehicle body (not shown) rearward of the occupant D). Therefore, when the airbag 32 is inflated and deployed, the pair of rear tethers 54 extend obliquely downward and rearward below the pair of front and rear extending portions 34A.

[0082] That is, the pair of rear tethers 54 assume an inclined posture inclined diagonally downward and rearward in side view. As a result, when the airbag 32 restrains the occupant D, the airbag body 40 is relatively drawn (pulled) diagonally downward and rearward by the pair of rear tethers 54, and the airbag body 40 and the front portions of the pair of front-rear extending portions 34A are relatively drawn diagonally downward and rearward around the headrest 18 in side view.

[0083] Next, the operation of the airbag device 30 and the method for folding the airbag 32 according to the first embodiment configured as described above will be described.

[0084] The airbag 32, which has a pair of front and rear chambers 34 and an airbag body 40, is stored in the headrest 18 of the vehicle seat 12 with the pair of front and rear chambers 34 at both ends in the seat width direction folded downward so as to fit the outer shape of the headrest 18. In other words, the airbag 32 is stored compactly inside the headrest 18, and this stored position is the initial position of the airbag 32.

[0085] Furthermore, the headrest 18 housing the airbag 32 is formed integrally with the seat back 16. Therefore, compared to when the headrest 18 is separate from the seat back 16, the airbag 32 (airbag device 30) can be prevented from becoming detached from the vehicle seat 12.

[0086] When a frontal collision of the vehicle is detected (or predicted) by the collision sensor, the inflator 44 is activated under the control of the control device. That is, gas is generated and ejected from the inflator 44. The gas ejected from the inflator 44 is supplied to the pair of front and rear chambers 34 and the rear connecting portion 34C of the airbag 32 through the distribution pipe 50.

[0087] Here, the inflator 44 is disposed singly along the extension direction of the seat back 16 of the vehicle seat 12, and ejects gas into the distribution pipe 50 that can supply gas to the pair of front and rear chambers 34 (left and right root portions 36L, 36R) and the rear connecting portion 34C (center root portion 38), respectively. In other words, gas ejected from the single inflator 44 disposed along the extension direction of the seat back 16 is supplied by the distribution pipe 50 to the pair of front and rear chambers 34 and the rear connecting portion 34C, respectively.

[0088] Therefore, compared to when the nozzles 44A of the inflators 44 are directly connected to the pair of front and rear chambers 34 (left and right root portions 36L, 36R) and the rear connecting portion 34C (central root portion 38), i.e., when three inflators 44 are arranged along a direction intersecting the extension direction of the seat back 16 (protruding diagonally downward and rearward) in a side view, it is possible to prevent the headrest 18 and seat back 16 from becoming larger (increased in thickness), and it is possible to reduce the number of parts and the installation space, thereby reducing manufacturing costs.

[0089] When gas is supplied to the pair of front and rear chambers 34 in this manner, the tear lines of the headrest 18 are torn apart by the inflation pressure of the pair of front and rear chambers 34, and as shown in Figure 11, the pair of front and rear chambers 34 inflate and deploy forward from the front of the headrest 18, passing through both the left and right sides of the head H of the occupant D.

[0090] At this time, the respective outlets 46A of the left and right branch pipes 46L, 46R connected to the left and right root portions 36L, 36R of the pair of front and rear chambers 34 extend outward and forward in the seat width direction at a predetermined angle and a predetermined length in a plan view, so that the pair of front and rear chambers 34 inflate and deploy as intended outward and forward in the seat width direction.

[0091] As a result, even if the pair of front and rear chambers 34 of the airbag 32 are folded downward relative to the airbag body 40 and stored in the headrest 18, the folded state is released when the airbag 32 is inflated and deployed. Therefore, even if the position of the head H of the occupant D varies in the left-right direction, the inflation and deployment performance of the pair of front and rear chambers 34 of the airbag 32 can be ensured.

[0092] Furthermore, as described above, when gas is supplied to the pair of front and rear chambers 34, gas is also supplied to the rear connecting portion 34C. That is, the rear connecting portion 34C inflates forward. Then, the tear line of the headrest 18 is torn open by the inflation pressure via the airbag body 40 of the rear connecting portion 34C, i.e., the pressing force of the inflated rear connecting portion 34C pressing the rolled-up airbag body 40 forward.

[0093] The airbag body 40, which is pushed forward by the inflated rear connecting portion 34C, moves forward along with the inflation and deployment of the pair of front and rear chambers 34, passing above the head H of the occupant D (see FIG. 11). At this time, since the pair of front and rear chambers 34 inflate and deploy toward the outside and front in the seat width direction, the airbag body 40 moves forward while being pulled outward in the seat width direction.

[0094] In this way, the airbag body 40 in a rolled-up state is forcibly pushed forward from the initial position by the rear connecting portion 34C, which is the push-out chamber, and is pulled outward in the seat width direction by the pair of front and rear chambers 34, while moving forward as the pair of front and rear chambers 34 inflate and deploy. Therefore, in the event of a frontal collision of the vehicle, the time that the airbag body 40 in a rolled-up state remains in the initial position is shortened.

[0095] Furthermore, when the airbag 32 is folded, it is provided in a flat shape, and the base fabric 40A of the airbag body 40 on the outer side in the seat width direction is pulled outward in the seat width direction. Therefore, the thickness of the airbag 32 due to overlapping base fabrics can be reduced, and the thickness of the airbag body 40 can be reduced. Therefore, when the airbag body 40 moves forward through a narrow gap between the head H of the occupant D and the ceiling 28 of the vehicle compartment, it is possible to prevent the airbag body 40 from getting stuck in the narrow gap, and it is possible to suppress or prevent poor deployment of the airbag 32.

[0096] In this way, when the pair of front and rear chambers 34 inflate and deploy, and the airbag body 40 in a rolled-up state moves forward, as shown in Figure 12, the head H of the occupant D is relatively inserted into the gap surrounded by the front and rear extension portions 34A of the pair of front and rear chambers 34 and the airbag body 40 in a rolled-up state.

[0097] 13 , gas is supplied from the front connecting portion 34B, which connects the front ends of the front and rear extending portions 34A of the pair of front and rear chambers 34 in the left-right direction, via the communication hole, causing the airbag body 40 to inflate and deploy toward the occupant D. In other words, the airbag body 40 is disposed between the pair of front and rear chambers 34 and in front of the occupant D.

[0098] As described above, gas is supplied to the airbag body 40 from the inflator 44 through the communication holes in the front connecting portion 34B after the pair of front and rear chambers 34 have been completely inflated and deployed. That is, the gas that is ejected from the inflator 44 and flows through the pair of front and rear extending portions 34A and the front connecting portion 34B is supplied to the airbag body 40 through the communication holes, and therefore the airbag body 40 is inflated and deployed with a delay relative to the pair of front and rear chambers 34.

[0099] Furthermore, the approximate vertical center portions of the base fabrics 34D of the pair of front and rear chambers 34 are pulled outward in the seat width direction and crushed in the drawing-out process, and the tip portions 34F of the pair of front and rear chambers 34 are roll-folded once from the front side toward the upper side in the roll-folding process. Then, the pair of front and rear chambers 34 excluding the tip portions 34F are accordion-folded three times in the accordion-folding process.

[0100] Here, accordion folding is known to deploy faster than roll folding. Therefore, when the pair of front and rear chambers 34 are folded accordion-like three times, the pair of front and rear chambers 34, except for the tip portions 34F, are inflated and deployed earlier than when the pair of front and rear chambers 34 are folded accordion-like four or more times. Furthermore, the tip portions 34F of the pair of front and rear chambers 34, which are folded in a roll only once, can control the airbag body 40 so that it does not inflate and deploy until it passes between the head H of the occupant D and the ceiling 28 of the vehicle compartment and moves forward.

[0101] Specifically, if the number of roll folds at the tip ends 34F of the pair of front and rear chambers 34 is, for example, 0.5, gas begins to flow into the airbag body 40 before the airbag body 40 moves forward between the head H of the occupant D and the ceiling 28 of the vehicle compartment, making it difficult for the airbag body 40 to move forward between the head H of the occupant D and the ceiling 28 of the vehicle compartment. Also, if the number of roll folds is, for example, 1.5, the flow of gas from the tip ends 34F of the pair of front and rear chambers 34 into the airbag body 40 after the airbag body 40 has moved forward becomes slower, so the inflation and deployment of the airbag body 40 toward the rear is slower.

[0102] In contrast, in the first embodiment, the airbag body 40 is folded into a roll only once, so gas does not begin to flow into the airbag body 40 before the airbag body 40 moves forward between the head H of the occupant D and the ceiling 28 of the vehicle compartment, and the airbag body 40 can easily move forward between the head H of the occupant D and the ceiling 28 of the vehicle compartment. Furthermore, after the airbag body 40 moves forward, gas flows into the airbag body 40 from the tip ends 34F of the pair of front and rear chambers 34 more quickly, so the airbag body 40 inflates and deploys rearward more quickly.

[0103] That is, according to the first embodiment, the airbag body 40 can be made to pass (move) reliably and quickly from the rear side to the front side through the narrow gap between the head H of the occupant D and the ceiling 28 of the vehicle cabin while remaining folded into a roll as the pair of front and rear chambers 34 inflate and deploy, and after passing through, can be quickly inflated and deployed toward the occupant D, thereby improving the deployment performance. Therefore, it is possible to quickly complete inflation and deployment of the airbag body 40 that is mounted in an initial position in a folded into a roll.

[0104] Moreover, in this first embodiment, the inner diameter of each of the outlets 46A of the left and right branch pipes 46L, 46R connected to the root portions 36L, 36R of the pair of front and rear chambers 34 is larger than the inner diameter of the outlet 48A of the branch pipe 48 connected to the root portion 38 of the rear connecting portion 34C. Therefore, the amount of gas supplied to the pair of front and rear chambers 34 can be made larger than the amount of gas supplied to the rear connecting portion 34C, which also enables the airbag body 40 to complete inflation and deployment more quickly.

[0105] As described above, according to the first embodiment, it is possible to improve the deployment performance of the airbag body 40, which is disposed in front of the occupant D, and to complete inflation and deployment more quickly by inflating and deploying through the gap between the head H of the occupant D and the ceiling 28 of the vehicle compartment. In particular, since the pushing structure that assists in pushing out the airbag body 40 is configured by the rear connecting portion 34C as a pushing chamber that interconnects the pair of front and rear chambers 34, the airbag body 40, which is folded into a roll, can be reliably pushed forward from its initial position by the rear connecting portion 34C.

[0106] Furthermore, when the airbag body 40 is inflated and deployed, the pair of front upper tethers 56 connect the left and right portions of the front side of the upper part of the airbag body 40 to the front portions of the pair of front-rear extending portions 34A, respectively. The pair of front upper tethers 56 can prevent the airbag body 40 from being accidentally displaced (rotated) upward about the front connecting portions 34B relative to the front-rear chamber 34 when inflation and deployment of the airbag body 40 (airbag 32) is complete.

[0107] Furthermore, when the airbag body 40 is inflated and deployed, the pair of front lower tethers 58 connect the left and right portions of the front side of the lower part of the airbag body 40 to the front portions of the pair of front-rear extending portions 34A, respectively. The pair of front lower tethers 58 can prevent the airbag body 40 from being inadvertently displaced (rotated) downward about the front connecting portions 34B relative to the front-rear chamber 34 when inflation and deployment of the airbag body 40 (airbag 32) is complete.

[0108] Furthermore, when the airbag 32 has completed inflation and deployment, the pair of rear tethers 54 extend obliquely downward and rearward below the pair of front-rear extending portions 34A. That is, the pair of rear tethers 54 restrict the movement of the airbag body 40 obliquely upward and forward. This makes it possible to suppress the swinging of the airbag 32 in the up-down and front-rear directions (contributing to stabilizing the deployment behavior of the airbag body 40).

[0109] In this state, the occupant D, who has inertially moved forward due to the impact of a frontal collision of the vehicle, is restrained by the airbag body 40. Specifically, when the occupant D is restrained, the front and rear chambers 34 (front and rear extensions 34A) are expanded forward due to the forward movement of the occupant D. Then, the airbag body 40 is pressed forward by the occupant D, and is compressed and deformed forward.

[0110] Therefore, it is possible to improve the energy absorption performance of the airbag body 40 and effectively ensure its occupant restraint performance. In other words, when both the front and rear chambers 34 and the airbag body 40 are subjected to a tensile load, the load applied from the airbag body 40 to the occupant D increases, but the compressive deformation of the airbag body 40 can reduce the load applied to the occupant D.

[0111] Moreover, the airbag body 40 is shaped so as to be sandwiched between the thighs F and chest C of the occupant D from the middle to late stages of restraining the occupant with the airbag 32, and is therefore able to make contact over a wide area with the upper body of the occupant D. This effectively reduces the load applied to the occupant D from the airbag body 40.

[0112] Furthermore, after the front and rear chambers 34 are inflated and deployed, the airbag body 40 is inflated and deployed toward the occupant D on the rear side of the front connecting portion 34B, thereby reducing the gap between the airbag body 40 and the occupant D. This allows the occupant D to be restrained by the airbag body 40 early, thereby improving the initial restraint performance of the airbag body 40 for the occupant D.

[0113] Furthermore, since the pair of rear tethers 54 are less likely to stretch than the front and rear chambers 34, when the occupant D is restrained, the airbag body 40 is pulled relatively diagonally downward and rearward by the pair of rear tethers 54. This makes it possible to stabilize the vertical position of the airbag body 40 with respect to the head H of the occupant D when the occupant is restrained. In other words, this airbag 32 makes it possible to appropriately restrain the occupant D.

[0114] Second Embodiment Next, an airbag device 30 according to a second embodiment will be described. Note that the same reference numerals are used to designate parts equivalent to those in the first embodiment, and detailed descriptions (including common functions) will be omitted as appropriate.

[0115] 14, the second embodiment differs from the first embodiment only in that the extrusion structure is configured with an extrusion chamber 35 separate from the pair of front and rear chambers 34, rather than a rear connecting portion 34C serving as an extrusion chamber that connects (interconnects) the rear ends of the pair of front and rear chambers 34 (front and rear extending portions 34A) in the left-right direction. That is, a cylindrical root portion 38 extending rearward is formed integrally with the rear surface of the extrusion chamber 35 in the center in the sheet width direction, and an outlet 48A of a branch pipe 48 is connected to the root portion 38.

[0116] Therefore, the same effects as those of the first embodiment can be obtained, and the airbag body 40 in a rolled-up state is reliably pushed forward from its initial position (mounted position) by the push-out chamber 35. In addition, in this second embodiment, the push-out chamber 35 is configured as a separate body from the pair of front and rear chambers 34, which simplifies the configuration of the airbag 32. In other words, the push-out chamber 35 also constitutes the airbag 32.

[0117] Third Embodiment Next, an airbag device 30 according to a third embodiment will be described. Note that the same reference numerals are used to designate parts equivalent to those of the first and second embodiments, and detailed descriptions (including common functions) will be omitted as appropriate.

[0118] As shown in Figure 15, in the third embodiment, two inflators 44 are provided: a first inflator 44B that supplies gas to the pair of front and rear chambers 34, and a second inflator 44C that supplies gas to the rear connecting portion 34C (or the extrusion chamber 35 shown in Figure 14), and the vehicle seat 12 is different from the first and second embodiments only in that it is provided with a first distribution pipe 51 that can supply gas ejected from the first inflator 44B to the pair of front and rear chambers 34, and a second distribution pipe 53 that can supply gas ejected from the second inflator 44C to the rear connecting portion 34C (or the extrusion chamber 35).

[0119] The first distribution pipe 51 is formed in a substantially "T" shape in a front view and has a cylindrical branch pipe 51L branching off from a center portion in the seat width direction to the left and a cylindrical branch pipe 51R branching off from the center portion in the seat width direction to the right. The outlets 51A of the left and right branch pipes 51L, 51R are connected to the base portions 36L, 36R of the pair of front and rear chambers 34, respectively. An outlet of the inflator 44B is connected to a cylindrical base portion of the first distribution pipe 51 extending downward from the center portion in the seat width direction.

[0120] The second distribution pipe 53 is disposed in approximately the center of the headrest 18 in the seat width direction, and extends upward from approximately the same position as the center of the first distribution pipe 51 in the seat width direction in a front view. An outlet 53A, which is the upper end of the second distribution pipe 53, is connected to the base 38 of the rear connecting portion 34C (or the extrusion chamber 35). The outlet of the inflator 44C is connected to a cylindrical base portion of the second distribution pipe 53 extending downward from the center of the seat width direction, and the inflator 44C is disposed at approximately the same height as the inflator 44B.

[0121] Furthermore, the inner diameter of each of the outlets 51A of the left and right branch pipes 51L, 51R of the first distribution pipe 51 is larger than the inner diameter of the outlet 53A of the second distribution pipe 53. As a result, similar to the first or second embodiment, the amount of gas supplied to the pair of front and rear chambers 34 can be made larger than the amount of gas supplied to the rear connecting portion 34C (or the extrusion chamber 35), and therefore, the airbag body 40 can be quickly inflated and deployed.

[0122] Furthermore, according to the third embodiment, only two inflators 44, a first inflator 44B and a second inflator 44C, are provided, so that the number of parts and the mounting space can be reduced, and manufacturing costs can be reduced, compared to a case where two inflators are provided for the pair of front and rear chambers 34 and one inflator is provided for the rear connecting portion 34C (or extrusion chamber 35).

[0123] Fourth Embodiment Next, an airbag device 30 according to a fourth embodiment will be described. Note that the same reference numerals are used to designate parts equivalent to those of the first and second embodiments, and detailed descriptions (including common functions) will be omitted as appropriate.

[0124] As shown in Figure 16, in this fourth embodiment, the extrusion structure differs from the first and second embodiments only in that it is composed of an extrusion cloth 26 that interconnects the pair of front and rear chambers 34, rather than a rear connecting portion 34C that serves as an extrusion chamber that connects (interconnects) the rear ends of the pair of front and rear chambers 34 (front and rear extending portions 34A) in the left-right direction, or an extrusion chamber 35 that is separate from the pair of front and rear chambers 34.

[0125] The extruded fabric 26 is formed in a rectangular shape with its longitudinal direction being the seat width direction in rear view, and is formed to be approximately the same size as the rear connecting portion 34C. The extruded fabric 26 is made of, for example, a polyamide or polyester fabric material, and both end portions in the seat width direction are attached by sewing to predetermined positions on the rear side of the base fabric 34D (see FIG. 5B) on the seat width direction inner side of each of the pair of front and rear chambers 34 (front and rear extending portions 34A).

[0126] Therefore, when the pair of front and rear chambers 34 inflate and deploy forward (specifically, forward and outward in the seat width direction), a predetermined tension is applied to the extrusion cloth 26 in the seat width direction. Therefore, the airbag body 40 folded into a roll is reliably extruded forward from its initial position (mounted position) by the extrusion cloth 26. In addition, in the fourth embodiment, the extrusion structure is formed by the extrusion cloth 26, which allows the airbag 32 to be stored compactly and made lighter.

[0127] As described above, the fourth embodiment does not include the rear connecting portion 34C or the extrusion chamber 35. Therefore, the fourth embodiment does not require the branch pipe 48 in the distribution pipe 50. In other words, the fourth embodiment is configured such that only the first distribution pipe 51 shown in FIG. 15 is provided.

[0128] Fifth Embodiment Next, an airbag device 30 according to a fifth embodiment will be described. Note that the same reference numerals are used to designate parts equivalent to those of the first and second embodiments, and detailed descriptions (including common functions) will be omitted as appropriate.

[0129] As shown in Figure 17, the fifth embodiment differs from the first and second embodiments only in that three inflators 44 are provided so as to be able to supply gas to each of the pair of front and rear chambers 34 and the rear connecting portion 34C (or the extrusion chamber 35 shown in Figure 14). That is, the outlets of the inflators 44L, 44R are directly connected to the respective root portions 36L, 36R of the pair of front and rear chambers 34, and the outlet of the inflator 44D is directly connected to the root portion 38 of the rear connecting portion 34C (or the extrusion chamber 35).

[0130] Therefore, in the fifth embodiment, the distribution pipe 50 is not required, but the three inflators 44L, 44R, 44D are configured to protrude in a direction (rearward and downward) intersecting the extending direction of the seat back 16 in a side view (not shown). Also, in the fifth embodiment, the outputs of the two inflators 44L, 44R that supply gas to the pair of front and rear chambers 34, respectively, are set to be higher than the output of the single inflator 44D that supplies gas to the rear connecting portion 34C (or the extrusion chamber 35).

[0131] Therefore, in this fifth embodiment, the headrest 18 and the seat back 16 are enlarged (thicker), but as in the first to third embodiments, the amount of gas supplied to the pair of front and rear chambers 34 can be increased more than the amount of gas supplied to the rear connecting portion 34C (or the extrusion chamber 35), thereby enabling the airbag body 40 to complete inflation and deployment more quickly.

[0132] Sixth Embodiment Next, an airbag device 30 according to a sixth embodiment will be described. Note that the same reference numerals are used to designate parts equivalent to those in the first embodiment, and detailed descriptions (including common functions) will be omitted as appropriate.

[0133] 18 , the sixth embodiment differs from the first embodiment in that, instead of folding the tip ends 34F of the pair of front and rear chambers 34 once, a valve mechanism 60 that momentarily blocks the inflow of gas is provided at the tip ends 34F. The valve mechanism 60 has a cylindrical valve body 62 whose inner diameter gradually decreases, and the valve body 62 is made of, like the base fabric of the airbag 32, a fabric material such as a polyamide or polyester material.

[0134] Each valve body 62 is attached by sewing its maximum inner diameter portion 62A around the entire circumference to the inner circumferential surface of the tip end portion 34F of each front / rear chamber 34. Each valve body 62 is disposed inside each front / rear chamber 34 with its minimum inner diameter portion 62B facing upstream in the gas inflow direction.

[0135] With the valve body 62 configured in this manner, when gas flows in the direction of arrow E as shown in FIG. 19A, the minimum inner diameter portion 62B of the valve body 62 bends toward the center of the valve body 62, instantaneously closing off the interior of each of the front and rear chambers 34, as shown in FIG. 19B.

[0136] 19C, when gas further flows in in the direction of arrow E, the minimum inner diameter portion 62B of the valve body 62 passes over the maximum inner diameter portion 62A from the inside and turns around to be positioned downstream in the direction of gas flow in. This opens the interior of each of the front and rear chambers 34, and gas is supplied from the tip ends 34F of each of the front and rear chambers 34 to the airbag body 40 folded into a roll.

[0137] As described above, according to the sixth embodiment, the valve mechanisms 60 that instantaneously block the inflow of gas are provided at the tip ends 34F of the pair of front and rear chambers 34, so that gas can be controlled not to flow into the airbag body 40 until it moves forward through the gap between the head H of the occupant D and the ceiling 28 of the vehicle compartment. Therefore, the airbag body 40 can move forward reliably and quickly, and as a result, the airbag body 40 can be quickly inflated and deployed.

[0138] Seventh Embodiment Finally, an airbag device 30 according to a seventh embodiment will be described. Note that the same reference numerals are used to designate parts equivalent to those in the first embodiment, and detailed descriptions (including common functions) will be omitted as appropriate.

[0139] As shown in Figures 20 and 21A, this seventh embodiment also differs from the first embodiment in that, instead of folding the tip ends 34F of the pair of front and rear chambers 34 into a roll just once, a valve mechanism 60 is provided at the tip ends 34F to momentarily block the inflow of gas.

[0140] This valve mechanism 60 is made up of a tape-like temporary fastening member 64 that is attached by sewing only the upper and lower ends together with the upper and lower peripheral edges of two long pieces of base fabric when the upper and lower peripheral edges of the two pieces are sewn together to form the front and rear chambers 34. Like the base fabric of the airbag 32, this temporary fastening member 64 is also made of a fabric material such as a polyamide or polyester material.

[0141] With this temporary fastening member 64, by inserting a portion of the tip 34F of each front and rear chamber 34, which is provided in a flat shape, upstream of the temporary fastening member 64 in the gas inflow direction between the temporary fastening member 64 and the base fabric 34D that faces the temporary fastening member 64 in the seat width direction, the interior of each front and rear chamber 34 can be instantaneously sealed, as shown in Figure 21A.

[0142] When gas further flows in in the direction of arrow E, a portion of each of the front and rear chambers 34 inserted between the temporary fastening member 64 and the base fabric 34D is removed from the space between them, and the interior of each of the front and rear chambers 34 is opened as shown in Fig. 21B. In other words, gas is supplied from the tip end 34F of each of the front and rear chambers 34 to the airbag main body 40 folded into a roll.

[0143] As described above, according to the seventh embodiment, the valve mechanisms 60 that instantaneously block the inflow of gas are provided at the tip ends 34F of the pair of front and rear chambers 34, so that gas can be controlled not to flow into the airbag body 40 until it moves forward through the gap between the head H of the occupant D and the ceiling 28 of the vehicle compartment. Therefore, the airbag body 40 can move forward reliably and quickly, and as a result, the airbag body 40 can be quickly inflated and deployed.

[0144] The seat-mounted airbag device 30 and the folding method of the airbag 32 according to this embodiment have been described above with reference to the drawings, but the seat-mounted airbag device 30 and the folding method of the airbag 32 according to this embodiment are not limited to those shown in the drawings, and design changes can be made as appropriate within the scope of the gist of this disclosure. For example, the extrusion structure is not limited to that shown in the drawings.

[0145] Furthermore, when folding the airbag 32, it may be folded, for example, on a mount (not shown) on which a reference line serving as a folding reference is marked. The number of roll folds and accordion folds in the pair of front and rear chambers 34 is not particularly limited as long as it can speed up the completion of inflation and deployment of the airbag body 40. In the case of a vehicle in which a relatively large gap is provided between the head H of the occupant D and the ceiling 28 of the vehicle compartment, the airbag body 40 may be folded inward in a roll, which is the opposite of the above embodiment.

[0146] However, it is preferable that the tip portions 34F of the pair of front and rear chambers 34 are rolled outward. With this, even if the airbag body 40 in a rolled state hits the upper rear end of the head H of the occupant D when it moves forward as the pair of front and rear chambers 34 are inflated and deployed, the airbag body 40 in a rolled state can move forward while rolling over the upper rear end of the head H of the occupant D.

[0147] The distribution pipes 50, 51, 53 may be provided so as to straddle the interior of the headrest 18 and the interior of the seat back 16. In addition, for example, in the first embodiment, the root portions 36, 38 are shown as being inserted into the inside of the respective outlets 46A, 48A and attached thereto, but this is not limitative, and the distribution pipes 50, 51, 53 may be configured to be attached so as to cover the outside of the respective outlets 46A, 48A.

[0148] The disclosure of Japanese Patent Application No. 2023-132161, filed on August 14, 2023, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. An airbag comprising: an inflator that is attached to a vehicle seat and ejects gas when the vehicle crashes; a pair of front and rear chambers that, as a result of being supplied with gas ejected from the inflator, inflate and deploy toward the front of the seat by passing through both the left and right sides of the head of an occupant seated in the vehicle seat; and an airbag body that is positioned on the front side of the seat of the occupant, passing between the occupant's head and the ceiling of the vehicle compartment as the pair of front and rear chambers inflate and deploy toward the rear of the seat between the pair of front and rear chambers by being supplied with gas from the pair of front and rear chambers; wherein the airbag device is provided on the seat rear side of the airbag body and has a pushing-out structure that pushes the airbag body toward the front of the seat.

2. The seat-mounted airbag device according to claim 1, wherein said extrusion structure is constituted by an extrusion chamber which interconnects said pair of front and rear chambers.

3. The seat-mounted airbag device according to claim 1, wherein said extrusion structure is constituted by an extrusion chamber separate from said pair of front and rear chambers.

4. The seat-mounted airbag device according to claim 1, wherein said extrusion structure is comprised of an extrusion fabric which interconnects said pair of front and rear chambers.

5. A seat-mounted airbag device as claimed in claim 2 or 3, wherein a single inflator is provided, and the vehicle seat is provided with a distribution pipe capable of supplying gas ejected from the inflator to the pair of front and rear chambers and the extrusion chamber, respectively, and the inner diameter of the outlet of the distribution pipe connected to the base portions of the pair of front and rear chambers is made larger than the inner diameter of the outlet of the distribution pipe connected to the base portion of the extrusion chamber.

6. A seat-mounted airbag device according to claim 5, wherein the headrest of the vehicle seat is formed integrally with the seat back of the vehicle seat, and the inflator is disposed along the extending direction of the seat back.

7. A seat-mounted airbag device as described in claim 2 or 3, wherein the inflators are two, a first inflator supplying gas to the pair of front and rear chambers and a second inflator supplying gas to the extrusion chamber, and the vehicle seat is provided with a first distribution pipe capable of supplying gas ejected from the first inflator to the pair of front and rear chambers and a second distribution pipe capable of supplying gas ejected from the second inflator to the extrusion chamber, and the inner diameter of the outlet of the first distribution pipe connected to the base portion of the pair of front and rear chambers is larger than the inner diameter of the outlet of the second distribution pipe connected to the base portion of the extrusion chamber.

8. A seat-mounted airbag device according to claim 7, wherein a headrest of the vehicle seat is integrally formed with a seat back of the vehicle seat, and the first inflator and the second inflator are disposed along an extending direction of the seat back.

9. A seat-mounted airbag device as claimed in claim 2 or 3, wherein three inflators are provided so as to be capable of supplying gas to the pair of front and rear chambers and the extrusion chamber, respectively, and the output of two inflators supplying gas to the pair of front and rear chambers, respectively, is set to be higher than the output of one inflator supplying gas to the extrusion chamber.

10. A seat-mounted airbag device according to any one of claims 1 to 4, wherein a valve mechanism for instantaneously blocking the inflow of gas is provided at the tip ends of the pair of front and rear chambers.

11. A method for folding an airbag having a pair of front and rear chambers that are supplied with gas ejected from an inflator provided in a vehicle seat in the event of a vehicle collision, and that inflate and deploy forward of the seat, passing through both the left and right sides of the head of an occupant seated in the vehicle seat, and an airbag body that moves toward the front of the seat through between the occupant's head and the ceiling of the vehicle compartment as the pair of front and rear chambers inflate and deploy toward the rear of the seat between the pair of front and rear chambers as the gas is supplied from the pair of front and rear chambers, the method comprising: providing the airbag made of a base fabric in a flat shape, and pulling out a part of the base fabric to the outside of the airbag in the seat width direction.

12. The method for folding an airbag according to claim 11, comprising: folding the tip portions of the pair of front and rear chambers in a roll-like manner from the front side of the seat toward the upper side of the seat a predetermined number of times; and folding the pair of front and rear chambers excluding the tip portions in an accordion-like manner a plurality of times.

13. The method for folding an airbag according to claim 12, wherein the number of times the roll folding is performed is one.

14. The method for folding an airbag according to claim 12 or 13, wherein the number of accordion folds is three.

15. A method for folding an airbag as described in claim 11, wherein pulling out a part of the base fabric constituting the airbag to the outside of the airbag in the seat width direction includes pulling out the base fabric on both the left and right sides that are embedded inside the airbag body to the outside of the airbag body in the seat width direction.

16. A method for folding an airbag as described in claim 11, wherein pulling out a part of the base fabric constituting the airbag to the outside of the airbag in the seat width direction includes pulling out approximately central parts in the up-down direction of the base fabric on both the left and right sides of the front and rear chambers to the outside of the front and rear chambers in the seat width direction.

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