Seat-mounted airbag device

Abstract

To obtain an in-seat airbag device that can inhibit rearward tilting of a neck of a passenger when a head of the passenger is restrained.SOLUTION: An in-seat airbag device 30 includes an airbag main body 32 having: a front-rear chamber 34 that is deployed passing a side of a head Ph of a passenger P toward a seat front side by a gas jetted from an inflator 28 which is actuated when a collision of a vehicle is detected or predicted and is disposed at the side of the head Ph of the passenger P; and a distal end chamber 36 that is deployed from a seat front side end portion of the front-rear chamber 34 toward the inner side in a seat width direction and is disposed at a seat front side of a face of the passenger P. The airbag main body 32 and a seat back frame 22 are connected by a force limiter mechanism 40 that moves the airbag main body 32 toward the seat front side when a load, which acts toward the seat front side and is applied to the airbag main body 32, exceeds a predetermined threshold value when the head ph of the passenger P is restrained.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a seat-mounted airbag device. [Background technology]

[0002] Side airbag devices comprising an airbag main body that deploys forward from one side of the seat back and is positioned to the side of the occupant's upper body (including the head) in the event of a diagonal frontal collision of the vehicle, and an airbag protrusion that deploys inward from the airbag main body in the seat width direction and is positioned in front of the occupant's face, with the two parts connected to each other by a planar tether, have been known for some time (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-008105 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned side airbag device is configured to restrain only the occupant's head, which moves diagonally forward, by the airbag protrusion located in front of the occupant's face. Therefore, when the occupant's head is restrained, the amount of forward movement of the occupant's head may be smaller than the amount of forward movement of the occupant's chest, which is determined by the restraining force of the seat belt, and the occupant's neck may tilt backward (bend backward) more.

[0005] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a seat-mounted airbag device that can suppress backward tilt of the occupant's neck when the occupant's head is restrained. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention No. 1 Aspects ofThe seat-mounted airbag device comprises an airbag body that deploys toward the front side of the seat by passing through the side of the occupant's head with gas ejected from an inflator that is activated when a vehicle collision is detected or predicted, and has front and rear chambers that are located on the side of the occupant's head, and a tip chamber that deploys inward in the width direction of the seat from the front end of the front and rear chambers and is located on the front side of the seat of the occupant's face, and the airbag body and seat back frame are connected by a force limiter mechanism that moves the airbag body toward the front side of the seat when a load applied to the airbag body toward the front side of the seat during head restraint exceeds a predetermined threshold value to restrain the occupant's head.

[0007] No. 1 Aspects of According to the invention, when a vehicle collision is detected or predicted, the inflator is activated to eject gas, and the front and rear chambers are deployed to the front side of the seat through the sides of the occupant's head and disposed to the side of the occupant's head, while the tip chamber is deployed from the front end of the front and rear chambers to the inside of the seat width direction and disposed to the front side of the occupant's face. Here, the airbag body and the seat back frame are connected by a force limiter mechanism. When the load applied to the front side of the seat applied to the airbag body during head restraint exceeds a predetermined threshold, the force limiter mechanism moves the airbag body to the front side of the seat. Therefore, when the occupant's head is restrained, the amount of forward movement of the occupant's head is suppressed from becoming smaller compared to the amount of forward movement of the occupant's chest determined by the restraining force of the seat belt. In other words, the occupant's head is allowed to stroke longer, and the load acting on the occupant's head is suppressed to be low. Thus, the backward tilt of the occupant's neck is suppressed.

[0008] Also, The present invention relates to 2 Aspects of The seat-mounted airbag device is No. 1 Aspects ofIn the seat-mounted airbag device, the force limiter mechanism includes a supply pipe that supplies gas ejected from the inflator to the airbag body attached to an upper end thereof, and a movable member whose lower end is supported on the seatback frame so as to be rotatable with the seat width direction as its axial direction, and an energy absorbing section that is provided between the supply pipe or the movable member and the seatback frame and that absorbs energy when the load exceeds a predetermined threshold while allowing the movable member to rotate toward the front of the seat.

[0009] No. 2 Aspects of According to the invention, when the load applied to the front side of the seat by the airbag body during restraint of the occupant's head exceeds a predetermined threshold, the energy absorbing portion allows the movable member to rotate toward the front side of the seat while absorbing the energy. In other words, the movable member and the supply pipe rotate toward the front side of the seat together with the airbag body. Therefore, when the occupant's head is restrained, the occupant's head can be made to stroke long, and the load acting on the occupant's head can be kept low. Therefore, the backward tilt of the occupant's neck is effectively suppressed.

[0010] Also, The present invention relates to 3 Aspects of The seat-mounted airbag device is No. 1 Aspects of a force limiter mechanism configured to connect the inflator fixed to the seatback frame to the airbag body and supply gas ejected from the inflator to the airbag body, a tube with an excess length that houses the supply pipe and connects the inflator and the airbag body, a reaction plate provided at the seat rear end of the airbag body, and an energy absorbing section provided between the reaction plate and the seatback frame that absorbs energy when the load exceeds a predetermined threshold while allowing the reaction plate to move toward the front of the seat.

[0011] No. 3 Aspects ofAccording to the invention, when the load applied to the front side of the seat by the airbag body during restraint of the occupant's head exceeds a predetermined threshold, the energy absorbing portion allows the reaction plate to move toward the front side of the seat while absorbing the energy. That is, the reaction plate moves toward the front side of the seat together with the airbag body. Therefore, when the occupant's head is restrained, the occupant's head is allowed to make a long stroke, and the load acting on the occupant's head is kept low. Thus, backward tilt of the occupant's neck is effectively suppressed. In addition, when the reaction plate moves toward the front side of the seat together with the airbag body, the airbag body comes off the supply pipe, but gas continues to be supplied to the airbag body because the tube extends. Therefore, even if the airbag body moves toward the front side of the seat, the occupant's head is effectively maintained in a restrained state. In addition, since no movable member is required, the configuration of the force limiter mechanism is simplified.

[0012] Also, The present invention relates to 4 Aspects of The seat-mounted airbag device is No. 2 or No. 3 Aspects of In the seat-mounted airbag device, the force limiter mechanism is configured to be deactivated by a load toward the front side of the seat when the airbag body is inflated and deployed.

[0013] No. 4 Aspects of According to the invention, the force limiter mechanism is deactivated by the load on the front side of the seat when the airbag body is inflated and deployed, and therefore the occupant's head is more effectively restrained than when the force limiter mechanism is activated by the load on the front side of the seat when the airbag body is inflated and deployed.

[0014] Also, The present invention relates to 5 Aspects of The seat-mounted airbag device is No. 4 Aspects ofIn a seat-mounted airbag device, the energy absorption portion includes a plate that absorbs energy by plastically deforming, and the thickness of some deformation regions of the plate is set to be thicker than the thickness of other deformation regions so that the plate can withstand the load toward the front side of the seat when the airbag body is inflated and deployed.

[0015] No. 5 Aspects of According to the invention, the thickness of a part of a deformation region of a plate that absorbs energy by plastic deformation is set to be thicker than the thickness of other deformation regions, so that the energy absorbing portion can withstand the load toward the front side of the seat when the airbag body is inflated and deployed. Therefore, the configuration of the energy absorbing portion is simplified compared to a case where a method other than setting the thickness of the deformation region of the plate is used to enable the energy absorbing portion to withstand the load toward the front side of the seat when the airbag body is inflated and deployed.

[0016] Also, The present invention relates to 6 Aspects of The seat-mounted airbag device is No. 4 Aspects of In the seat-mounted airbag device, the force limiter mechanism includes an actuator that activates the force limiter mechanism when the load exceeds a predetermined threshold value.

[0017] No. 6 Aspects of According to the invention, when the occupant's head is restrained, the force limiter mechanism is activated by the actuator at the timing when the load applied to the airbag body toward the front side of the seat exceeds a predetermined threshold value. Therefore, the force limiter mechanism is activated more reliably than when the force limiter mechanism is activated using a method other than the actuator. Effect of the Invention

[0018] As described above, according to the present invention, in a seat-mounted airbag device, it is possible to suppress backward tilt of the neck of an occupant when the head of the occupant is restrained. [Brief description of the drawings]

[0019] [Figure 1] FIG. 2 is a side view showing a state after the seat-mounted airbag device according to the first embodiment has been deployed. [Diagram 2] FIG. 2 is a plan view showing a state after the seat-mounted airbag device according to the first embodiment has been deployed. [Diagram 3] FIG. 2 is a perspective view showing a configuration of a force limiter mechanism of the seat-mounted airbag device according to the first embodiment. [Figure 4] FIG. 2 is a left half front view showing the configuration of a force limiter mechanism of the seat-mounted airbag device according to the first embodiment. [Diagram 5] FIG. 2 is a perspective view showing a configuration of an energy absorbing portion in a force limiter mechanism of the seat-mounted airbag device according to the first embodiment. [Figure 6] 1A is a plan view showing the configuration of an energy absorbing portion in the force limiter mechanism of the seat-mounted airbag device according to the first embodiment, and FIG. 1B is a side view showing the configuration of the energy absorbing portion in the force limiter mechanism of the seat-mounted airbag device according to the first embodiment. [Figure 7] FIG. 2 is a side view showing a state in which a force limiter mechanism of the seat-mounted airbag device according to the first embodiment is activated. [Figure 8] 4 is a graph showing the load-displacement characteristics (FS characteristics) when the head of an occupant is restrained by the seat-mounted airbag device according to the first embodiment. [Figure 9] FIG. 11 is a side view showing a modified example of the force limiter mechanism of the seat-mounted airbag device relating to the first embodiment. [Figure 10] 5 is an enlarged plan view, partly in section, showing the configuration of a modified example of the force limiter mechanism of the seat-mounted airbag device according to the first embodiment. FIG. [Figure 11] FIG. 11 is a side view showing a state after the seat-mounted airbag device according to the second embodiment has been deployed. [Figure 12]FIG. 11 is a left half front view showing the configuration of a force limiter mechanism of a seat-mounted airbag device according to a second embodiment. [Figure 13] FIG. 11 is a side view showing a state in which a force limiter mechanism of the seat-mounted airbag device according to the second embodiment is activated. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. For the sake of convenience, the arrow UP shown in each drawing indicates the seat upper direction, the arrow FR indicates the seat front direction, and the arrow RH indicates the seat right direction. Therefore, in the following description, when the directions such as up / down, front / rear, and left / right are mentioned without special mention, they refer to the up / down, front / rear, and left / right directions of the vehicle seat. The left / right direction is also synonymous with the seat width direction.

[0021] 1 and 2, a seat-mounted airbag device (hereinafter simply referred to as "airbag device") 30 according to this embodiment is provided on the outer side in the seat width direction (left side in the figure) of a vehicle seat 10. Note that, although the vehicle seat 10 according to this embodiment is described as a rear seat, this airbag device 30 may also be provided in a front seat. In addition, the rear seat is, as an example, a rear seat on the right side window (not shown) side.

[0022] Therefore, the airbag body 32, which will be described later, deploys by passing between the head Ph of the occupant P on the side window side and the head of an occupant (not shown) on the center seat side. The airbag body 32 may be configured to deploy by passing between the side window and the head Ph of the occupant P. In addition, the "occupant P" in this embodiment is, as an example, an occupant equivalent to the human body dummy AM50 (the 50th percentile of adult American males).

[0023] First Embodiment First, an airbag device 30 according to a first embodiment will be described. As shown in Fig. 1 and Fig. 2, a vehicle seat 10 has a seat cushion 12 on which an occupant P sits (supporting the buttocks and thighs of the occupant P), a seat back 14 supporting the back of the occupant P, and a headrest 16 supporting the head Ph of the occupant P.

[0024] 3 and 4, the headrest 16 is provided in a vertically movable manner in the center of the seat width direction at the upper end of the seat back 14 (see Figs. 1 and 2). More specifically, a pair of cylindrical headrest stays 18 are provided on the left and right sides of the underside of the headrest 16 in the center of the seat width direction.

[0025] Each headrest stay 18 is inserted into a pair of generally cylindrical headrest supports 26 provided on the left and right sides of the upper end portion (upper frame 24 described later) of the seat back 14 in the center in the seat width direction, so that the headrest stays 18 can be raised and lowered and can be fixed at a plurality of predetermined positions. This makes it possible to adjust the height position of the headrest 16 to match the position of the head Ph of the occupant P. A case portion 20 that houses an airbag main body 32 described later is disposed on the left side of the headrest 16.

[0026] As shown in Figures 1 and 2, the airbag device 30 has an airbag body 32 that breaks off a part of the case portion 20 and pops out when gas is ejected from an inflator 28 described later, and deploys from the rear side (more specifically, the left rear side) of the head Ph of an occupant P seated in the vehicle seat 10 to the front side.

[0027] The airbag body 32 has a front-rear chamber 34 that passes through the left side of the head Ph of the occupant P and deploys forward and is disposed to the left side of the head Ph of the occupant P (between the head Ph of the occupant P on the side window side and the head of an occupant in the center seat (not shown)), and a front end chamber 36 that deploys inward in the seat width direction from the front end of the front-rear chamber 34 and is disposed in front of the face of the occupant P and to the right side of the head Ph of the occupant P. In other words, the airbag body 32 is bent into a substantially "J" shape in a plan view so as to be able to restrain at least the head Ph of the occupant P.

[0028] The airbag body 32 has a thin cloth-like upper tether 37 that connects the deployment direction intermediate portion 36U at the upper end of the tip chamber 36 and the deployment direction intermediate portion 34U at the upper ends of the front and rear chambers 34, and a thin cloth-like lower tether 38 (see Figure 1) that connects the deployment direction intermediate portion 36D (see Figure 1) at the lower end of the tip chamber 36 and the deployment direction intermediate portion 34D (see Figure 1) at the lower ends of the front and rear chambers 34.

[0029] More specifically, when the airbag body 32 is inflated and deployed, the upper tether 37 is formed in a generally right-angled triangle shape in a plan view, with the hypotenuse being a straight-line rear edge portion 37A connecting a deployment direction intermediate portion 36U at the upper end of the tip chamber 36 and a deployment direction intermediate portion 34U at the upper ends of the front and rear chambers 34.

[0030] The peripheral edge of this upper tether 37, excluding its rear edge portion 37A, is attached by sewing to the upper ends of the front and rear chambers 34 and the upper end of the tip chamber 36, from the middle portion 34U in the deployment direction at the upper end of the front and rear chambers 34 to the middle portion 36U in the deployment direction at the upper end of the tip chamber 36.

[0031] Similarly, when the airbag body 32 is inflated and deployed, the lower tether 38 is formed, when viewed from the bottom, into an approximately right-angled triangle shape whose hypotenuse is a straight-line rear edge portion (not shown) connecting the deployment direction intermediate portion 36D at the lower end of the tip chamber 36 and the deployment direction intermediate portion 34D at the lower ends of the front and rear chambers 34.

[0032] The peripheral edge of this lower tether 38, excluding its rear edge, is attached by sewing to the lower end of the front and rear chambers 34 and the lower end of the tip chamber 36, from the middle portion 34D in the deployment direction at the lower end of the front and rear chambers 34 to the middle portion 36D in the deployment direction at the lower end of the tip chamber 36.

[0033] 1, the upper tether 37 is located above the head Ph of the occupant P, and therefore does not interfere with (make contact with) the head Ph of the occupant P. The lower tether 38 is located at the neck of the occupant P, but as described above, since it is made of a thin cloth, even if it interferes with (makes contact with) the neck, the injury value to the neck is low.

[0034] 3 and 4, a pair of left and right seat back frames, each of which extends in the vertical direction and is generally U-shaped in a plan cross section, is provided on each of the left and right sides of the interior of the seat back 14 with its opening facing inward in the seat width direction. An upper frame 24, which is one of the seat back frames and is generally U-shaped in a front view, is installed on the upper ends of the left and right side frames 22, and a pair of left and right headrest supports 26 is integrally provided in the center of the upper frame 24 in the seat width direction.

[0035] 1 to 4, the lower end of a movable plate 44 serving as a movable member constituting the force limiter mechanism 40 is supported by a shaft 42 at the lower end on the outer surface side of the left side frame 22 so as to be rotatable about the seat width direction as the axial direction, at a lower end on the outer surface side of the left side frame 22. The movable plate 44 is formed in a flat plate shape extending in the vertical direction, and its width is smaller than that of the side frame 22.

[0036] The inflator 28 is fixed to the outer surface side of the movable plate 44. That is, the inflator 28 is formed in a substantially cylindrical shape with a bottom, and a part of its outer circumferential surface is integrally attached to the outer surface of the movable plate 44 via a bracket (not shown) or the like, with its axis facing up and down.

[0037] The inflator 28 is electrically connected to an airbag ECU (not shown) provided in the vehicle, and a detection device (not shown) such as an acceleration sensor provided in the vehicle is electrically connected to the airbag ECU. Therefore, when a vehicle collision is detected by the detection device, the inflator 28 is activated via the airbag ECU to instantly eject gas.

[0038] Incidentally, the inflator 28 may be configured to be activated not only when a vehicle collision is detected, but also when a vehicle collision is predicted by a collision prediction sensor or the like (not shown).

[0039] The lower end of a metal pipe 46 serving as a supply pipe constituting the force limiter mechanism 40 together with the movable plate 44 is fitted and attached to the outlet 28A, which is the upper end of the inflator 28. The upper side of the metal pipe 46 is bent inward in the seat width direction in a crank shape so as to fit the shape of the seat back 14. The rear end of the airbag body 32 is attached to the upper end 46A of the metal pipe 46.

[0040] In other words, the metal tube 46 is configured to be able to supply gas ejected from the inflator 28 to the airbag body 32 attached to the upper end thereof, and is also configured to be able to position the airbag body 32 close to the head Ph of the occupant P. The rear end of the airbag body 32 and the side frame 22 are connected by the metal tube 46 and the movable plate 44 (through the inflator 28) that constitute the force limiter mechanism 40.

[0041] 2, the movable plate 44 to which the inflator 28 is fixed and the metal tube 46 below the case portion 20 are provided inside the seat back 14. Therefore, as will be described later, when the movable plate 44 and the metal tube 46 rotate forward, they break the cover of the seat back 14 and rotate forward.

[0042] 5, an energy absorbing section 50 which constitutes the force limiter mechanism 40 together with the movable plate 44 and the metal tube 46 is provided between the metal tube 46 (or the movable plate 44) and the upper frame 24. The energy absorbing section 50 is configured to operate when the load (tensile load) applied to the front side of the airbag body 32 exceeds a predetermined threshold value (reach a predetermined load G2 shown in FIG. 8) during head restraint to restrain the head Ph of the occupant P, and to allow the movable plate 44 and the metal tube 46 to rotate forward while absorbing energy with a certain load (load G3 lower than load G2).

[0043] That is, as shown in Figures 5 and 6, the energy absorption section 50 is composed of a metal strip-shaped plate 52 that absorbs a constant amount of energy by being plastically deformed (handled) and sent forward by the roll section 54 described later, and the roll section 54 around which the plate 52 is wound.

[0044] The plate 52 is supported in a rolled-up state (not shown) on a lower frame (not shown) which is one of the seat back frames so as to be able to be retracted. The free end 52A of the plate 52 is wound around the roll portion 54 and then attached and fixed to the outer circumferential surface of the metal tube 46 by screws or the like (see FIG. 5).

[0045] The roll section 54 is supported by the upper frame 24, and has three rolls, a front roll 54F, a central roll 54C, and a rear roll 54B, which are arranged at a predetermined interval from the front side. The free end 52A side of the plate 52 is wound around the rear roll 54B, passes through the gap between the rear roll 54B and the central roll 54C, is wound around the central roll 54C, and is further wound around the front roll 54F through the gap between the central roll 54C and the front roll 54F.

[0046] Furthermore, in the plate 52, under normal circumstances (before being sent forward), the thickness of the plastic deformation region of the portion (part) wound around the roll portion 54 is set to be thicker than the thickness of the other plastic deformation regions (see FIG. 6(B)). As a result, the force limiter mechanism 40 is configured not to operate under a load (tensile load shown as load G1 in FIG. 8) toward the front side when the airbag body 32 is inflated and deployed.

[0047] That is, the plate 52 does not pass through the roll portion 54 or passes through it very difficultly due to the load (tensile load) toward the front side when the airbag body 32 is inflated and deployed, and this prevents the plate 52 from being sent out toward the front side. In other words, the plate 52 is designed to withstand (withstand and not move against) the load (tensile load) toward the front side when the airbag body 32 is inflated and deployed.

[0048] Next, the operation of the airbag device 30 according to the first embodiment configured as above will be described.

[0049] When the detection device detects that the vehicle has experienced a frontal collision, the inflator 28 is activated and instantly ejects gas into the airbag body 32. When the gas is ejected into the airbag body 32, the airbag body 32 deploys (the airbag body 32 presses against the case 20 from the inside), causing the case 20 to break.

[0050] The airbag body 32 then deploys forward from the case 20 through the left side of the head Ph of the occupant P (the gap between the head Ph of the occupant P on the side window side and the head of the occupant on the center seat side (not shown)). That is, when the front and rear chambers 34 inflate and deploy and are positioned to the left side of the head Ph of the occupant P, gas flows from the front end of the front and rear chambers 34 into the tip chamber 36, causing the tip chamber 36 to inflate and deploy inward in the seat width direction.

[0051] Then, at least the head Ph of the occupant P seated in the vehicle seat 10 is restrained by the fully deployed airbag body 32 (the front and rear chambers 34 and the tip chamber 36). That is, the airbag body 32 (the front and rear chambers 34 and the tip chamber 36) can restrain at least the head Ph of the occupant P from moving forward due to inertial force.

[0052] Here, the rear end of the airbag body 32 and the side frame 22 are connected by a force limiter mechanism 40. When the load (tensile load) applied to the airbag body 32 toward the front during head restraint to restrain the head Ph of the occupant P exceeds a predetermined threshold value (reaches a predetermined load G2 shown in FIG. 8), the force limiter mechanism 40 moves the airbag body 32 forward as shown in FIG.

[0053] Specifically, the plate 52 constituting the energy absorbing section 50 passes through the roll section 54 and is sent out while being plastically deformed (handled) so that its thickness is reduced, thereby absorbing a certain amount of energy and allowing the movable plate 44 and the metal tube 46 to rotate forward. That is, the movable plate 44 and the metal tube 46 rotate (move) forward together with the airbag body 32.

[0054] Therefore, when the head of the occupant P is restrained, the amount of forward movement of the head Ph of the occupant P can be prevented from becoming smaller than the amount of forward movement of the chest of the occupant P, which is determined by the restraining force of the seat belt. In other words, the head Ph of the occupant P can be made to have a long stroke (movement) forward, and the rearward load acting on the head Ph of the occupant P can be kept low. Therefore, the backward tilt of the neck of the occupant P can be effectively prevented.

[0055] Furthermore, the force limiter mechanism 40 is not activated by a load (tensile load shown as load G1 in FIG. 8) toward the front side when the airbag body 32 is inflated and deployed. That is, the thickness of the plastic deformation region of a part of the plate 52 (the part wrapped around the roll portion 54) that absorbs energy by plastic deformation is set to be thicker than the thickness of the other plastic deformation regions, so that the airbag body 32 can withstand the load (tensile load) toward the front side when it is inflated and deployed.

[0056] Therefore, the head Ph of the occupant P can be more effectively restrained compared to a case in which the force limiter mechanism 40 is activated by a load (tensile load) toward the front side when the airbag body 32 is inflated and deployed. Also, the configuration of the energy absorbing section 50 can be simplified compared to a case in which a method other than setting the thickness of the plastic deformation region of the plate 52 is used to make the energy absorbing section 50 capable of withstanding the load toward the front side when the airbag body 32 is inflated and deployed.

[0057] Fig. 8 shows the load-displacement characteristics (FS characteristics) of the airbag body 32 when the head of the occupant P is restrained, specifically, the relationship between the load applied to the plate 52 and the amount of head movement of the occupant P. As shown in Fig. 8, the amount of head movement of the occupant P is small with a load G1 applied to the plate 52 when the airbag body 32 is inflated and deployed. In other words, the force limiter mechanism 40 does not operate.

[0058] Thereafter, when the airbag body 32 restrains the head and a predetermined load G2 is reached (exceeds a predetermined threshold), the force limiter mechanism 40 (energy absorbing section 50) is activated, so that the load acting on the head Ph of the occupant P (on the plate 52) is kept lower than the load G2, and the head Ph of the occupant P can be stroked (moved) a long distance with that constant load.

[0059] (Modification) 9 and 10 may be used as a configuration for deactivating force limiter mechanism 40 when the airbag body 32 is inflated and deployed and the load to the front side (tensile load shown as load G1 in FIG. 8) is applied. That is, force limiter mechanism 40 may be configured to include an actuator 60 that activates force limiter mechanism 40 when the head of occupant P is restrained and when a predetermined load G2 is reached (when a predetermined threshold value is exceeded).

[0060] More specifically, the actuator 60 is provided on the upper side of the side frame 22, and has, inside a hollow cylindrical case 62 that is circular in side view, a coil spring 66 as a biasing member, and an engagement portion 64 that protrudes outward in the seat width direction (to the left) by the biasing force of the coil spring 66. The engagement portion 64 is formed in a substantially "T" shape in plan view, and has a disc portion 64A and a columnar portion 64B that is integrally provided at the axial center portion of the disc portion 64A.

[0061] A circular through hole 62B having an inner diameter larger than the outer diameter of the cylindrical portion 64B is formed in an outer wall portion 62A of the case 62 on the outer side in the seat width direction, and the cylindrical portion 64B protrudes outward in the seat width direction from the through hole 62B. Note that the engagement portion 64 is configured such that the amount of protrusion of the cylindrical portion 64B from the outer wall portion 62A is limited by the outer peripheral edge portion of the disk portion 64A interfering with (abutting on) a stopper portion 63 protruding from the inner surface of the peripheral wall 62C of the case 62.

[0062] An outlet of a micro gas generator (MGG) 68 is inserted into a through hole 62D provided in the peripheral wall 62C between the disk portion 64A (stopper portion 63) of the engagement portion 64 and the outer wall portion 62A, so that gas can be ejected into the space between the disk portion 64A and the outer wall portion 62A of the engagement portion 64. In other words, when gas is ejected from the micro gas generator 68, the engagement portion 64 moves inward in the seat width direction against the biasing force of the coil spring 66, and the cylindrical portion 64B is pulled into the case 62.

[0063] Meanwhile, a cylindrical ring portion 48 is fitted and fixed to the metal tube 46, and a rectangular flat flange portion 48A protruding rearward is integrally formed on the outer circumferential surface of the ring portion 48. A circular through hole 48B penetrating in the seat width direction is formed in the flange portion 48A, with an inner diameter the same as that of the through hole 62B, for example, and the columnar portion 64B, the protruding amount of which is limited by the stopper portion 63, can be inserted into the through hole 48B.

[0064] That is, the cylindrical portion 64B of the engagement portion 64 is inserted into the through hole 48B of the flange portion 48A, thereby locking the metal tube 46 and the movable plate 44 so as to prevent them from rotating forward. Then, when gas is ejected from the micro gas generator 68, the cylindrical portion 64B is drawn into the case 62 and removed from the through hole 48B, thereby enabling the metal tube 46 and the movable plate 44 to rotate forward (the lock is released).

[0065] With actuator 60 configured in this manner, the force limiter mechanism 40 can be deactivated by a load (tensile load) toward the front side when airbag body 32 is inflated and deployed, and the force limiter mechanism 40 can be activated by gas being ejected from micro gas generator 68 when the head of occupant P is restrained and a predetermined load G2 is reached (when a predetermined threshold is exceeded). Therefore, compared to activating force limiter mechanism 40 using a method other than actuator 60, force limiter mechanism 40 can be activated more reliably.

[0066] <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 the same parts as those in the first embodiment, and detailed descriptions thereof will be omitted as appropriate.

[0067] 11 and 12, the airbag device 30 according to the second embodiment differs from the first embodiment only in that it is provided with a force limiter mechanism 70 that is different from the force limiter mechanism 40. In the force limiter mechanism 70 according to the second embodiment, the movable plate 44 is not provided, and the inflator 28 is directly fixed to the outer surface of the side frame 22.

[0068] That is, the inflator 28 has its axis oriented in the vertical direction, and a part of its outer circumferential surface is integrally attached to the outer surface of the side frame 22 via the bracket 23 or the like. The inflator 28 is attached by fitting the lower end of a metal pipe 72 serving as a supply pipe constituting the force limiter mechanism 70 into the outlet 28A, which is the upper end of the inflator 28, and the rear end of the airbag body 32 is attached to the upper end of the metal pipe 72.

[0069] That is, the metal tube 72 is fixed to the side frame 22 via the inflator 28, and is capable of supplying gas ejected from the inflator 28 to the airbag body 32 attached to the upper end of the metal tube 72. Also, a tube 74 with an excess length is provided on the outer periphery of the metal tube 72, connecting the upper end of the inflator 28 and the rear end of the airbag body 32. In other words, the metal tube 72 is housed inside the tube 74.

[0070] The rear end of the airbag body 32 is connected to the side frame 22 by the metal pipe 72 and the tube 74 that constitute the force limiter mechanism 70. As will be described later, when the airbag body 32 moves forward, the rear end of the airbag body 32 comes off the upper end of the metal pipe 72.

[0071] That is, the upper end of the metal tube 72 is configured to come off the rear end of the airbag body 32 when a load (tensile load) applied to the airbag body 32 toward the front side exceeds a predetermined threshold value. Also, at this time, the middle part of the tube 74 is configured to be supported (bent into a substantially ">" shape) by a cylindrical guide part 78 provided on the upper frame 24 or the like with the seat width direction as the axial direction.

[0072] A flat reaction plate 76 is attached to the rear end of the airbag body 32. An energy absorbing section 56 that constitutes a force limiter mechanism 70 together with the metal pipe 72, the tube 74 and the reaction plate 76 is provided between the reaction plate 76 and the side frame 22 (or a lower frame, not shown).

[0073] The energy absorbing section 56 is configured to be activated when the load (tensile load) applied to the airbag body 32 toward the forward side exceeds a predetermined threshold value (when it reaches a predetermined load G2 shown in FIG. 8) during head restraint to restrain the head Ph of the occupant P, and to allow the reaction plate 76 (airbag body 32) to move forward while absorbing energy with a constant load (load G3 lower than load G2).

[0074] That is, the energy absorbing section 56 is configured similarly to the energy absorbing section 50 in the first embodiment, and includes the plate 52 and the roll section 58 around which the plate 52 is wound. That is, the energy absorbing section 56 differs from the energy absorbing section 50 in the first embodiment only in the configuration of the roll section 58.

[0075] More specifically, the roll portion 58 is supported within the case portion 20 which houses the airbag body 32 and the upper ends of the metal tube 72 and the tube 74, and has five rolls, from the upper front side, namely, a first roll 58A and a second roll 58B, a third roll 58C provided below them, a fourth roll 58D provided below them, and a fifth roll 58E provided below them.

[0076] The free end 52A (see Figures 5 and 6) of the plate 52 is wound around the fifth roll 58E from the rear, then around the fourth roll 58D from the front, and then around the third roll 58C from the rear, and finally passes through the gap between the second roll 58B and the first roll 58A and is fixed to the reaction plate 76.

[0077] Furthermore, in the plate 52, under normal circumstances (before being sent forward), the thickness of the plastic deformation region of the portion (part) wound around the roll portion 58 is set to be thicker than the thickness of the other plastic deformation regions. This is configured so that the force limiter mechanism 70 is deactivated by the load (tensile load shown as load G1 in FIG. 8) toward the front side when the airbag body 32 is inflated and deployed.

[0078] That is, the plate 52 does not pass through the roll portion 58 or passes through it very difficultly due to the load (tensile load) toward the front side when the airbag body 32 is inflated and deployed, and this prevents the plate 52 from being sent out toward the front side. In other words, the plate 52 is designed to withstand (withstand and not move against) the load (tensile load) toward the front side when the airbag body 32 is inflated and deployed.

[0079] Next, the operation of the airbag device 30 according to the second embodiment configured as above will be described. Note that the description of the operation common to the first embodiment will be omitted as appropriate.

[0080] When the detection device detects that the vehicle has experienced a frontal collision, the inflator 28 is activated and instantly ejects gas into the airbag body 32. When the gas is ejected into the airbag body 32, the airbag body 32 deploys (the airbag body 32 presses against the case 20 from the inside), causing the case 20 to break.

[0081] The airbag body 32 then deploys forward from the case 20 through the left side of the head Ph of the occupant P (the gap between the head Ph of the occupant P on the side window side and the head of the occupant on the center seat side (not shown)). That is, when the front and rear chambers 34 inflate and deploy and are positioned to the left side of the head Ph of the occupant P, gas flows from the front end of the front and rear chambers 34 into the tip chamber 36, causing the tip chamber 36 to inflate and deploy inward in the seat width direction.

[0082] Then, at least the head Ph of the occupant P seated in the vehicle seat 10 is restrained by the fully deployed airbag body 32 (the front and rear chambers 34 and the tip chamber 36). That is, the airbag body 32 (the front and rear chambers 34 and the tip chamber 36) can restrain at least the head Ph of the occupant P from moving forward due to inertial force.

[0083] Here, the rear end of the airbag body 32 and the side frame 22 are connected by a force limiter mechanism 70. When the load (tensile load) applied to the airbag body 32 toward the front side during head restraint to restrain the head Ph of the occupant P exceeds a predetermined threshold value (reaches a predetermined load G2 shown in FIG. 8), the force limiter mechanism 70 moves the airbag body 32 forward as shown in FIG.

[0084] Specifically, the plate 52 constituting the energy absorbing section 56 shown in Fig. 11 passes through the roll section 58 and is sent out while being plastically deformed (handled) so that its thickness is reduced, thereby absorbing a certain amount of energy and allowing the reaction plate 76 to move forward. That is, the reaction plate 76 moves forward together with the airbag body 32.

[0085] Therefore, when the head of the occupant P is restrained, the amount of forward movement of the head Ph of the occupant P can be prevented from becoming smaller than the amount of forward movement of the chest of the occupant P, which is determined by the restraining force of the seat belt. In other words, the head Ph of the occupant P can be made to have a long stroke (movement) forward, and the rearward load acting on the head Ph of the occupant P can be kept low. Therefore, the backward tilt of the neck of the occupant P can be effectively prevented.

[0086] Furthermore, the force limiter mechanism 70 is not activated by a load (tensile load shown as load G1 in FIG. 8) toward the front side when the airbag body 32 is inflated and deployed. That is, the thickness of the plastic deformation region of a part of the plate 52 (the part wrapped around the roll portion 58) that absorbs energy by plastic deformation is set to be thicker than the thickness of the other plastic deformation regions, so that the airbag body 32 can withstand the load (tensile load) toward the front side when it is inflated and deployed.

[0087] Therefore, the head Ph of the occupant P can be more effectively restrained compared to a case in which the force limiter mechanism 70 is activated by a load (tensile load) toward the front side when the airbag body 32 is inflated and deployed. Also, the configuration of the energy absorbing section 56 can be simplified compared to a case in which a method other than setting the thickness of the plastic deformation region of the plate 52 is used to make the energy absorbing section 56 capable of withstanding the load toward the front side when the airbag body 32 is inflated and deployed.

[0088] 13, when the reaction plate 76 moves forward together with the airbag body 32, the rear end of the airbag body 32 comes off the upper end of the metal tube 72, but the tube 74 extends, so gas continues to be supplied to the airbag body 32. Therefore, even if the airbag body 32 moves forward, the head of the occupant P can be effectively restrained. Also, since the movable plate 44 in the first embodiment is not necessary, the configuration of the force limiter mechanism 70 can be simplified.

[0089] Although the seat-mounted airbag device 30 according to this embodiment has been described above with reference to the drawings, the seat-mounted airbag device 30 according to this embodiment is not limited to the one shown in the drawings, and the design can be appropriately modified within the scope of the gist of the present invention. For example, the supply pipe is not limited to one made of metal (metal pipe 46 and metal pipe 72), and may be one made of resin.

[0090] Furthermore, the energy absorbing section 50 is not limited to a configuration having the plate 52 and the roll section 54, and the energy absorbing section 56 is not limited to a configuration having the plate 52 and the roll section 58. Although not shown, the energy absorbing sections 50 and 56 may be configured to include, for example, a torsion bar provided on a retractor. In this case as well, the configuration of the energy absorbing sections 50 and 56 can be simplified. [Explanation of symbols]

[0091] 22 Side frame (seat back frame) 28 Inflator 30 Airbag device (seat-mounted airbag device) 32 Airbag body 34 Front and rear chambers 36 Tip Chamber 40 Force limiter mechanism 44 Movable plate (movable part) 46 Metal pipe (supply pipe) 50 Energy absorption section 52 Plate 56 Energy absorption section 60 Actuator 70 Force limiter mechanism 72 Metal pipe (supply pipe) 74 Tube 76 Reaction Plate P Crew Ph head

Claims

1. an airbag body having: a front and rear chamber that is deployed to the front side of a seat by gas ejected from an inflator that is activated when a vehicle collision is detected or predicted, passing through the sides of the head of an occupant and being disposed on the sides of the head of the occupant; and a tip chamber that is deployed inward in the seat width direction from the front end of the front and rear chambers and is disposed on the front side of the face of the occupant in the seat; the airbag body and the seat back frame are connected to each other by a force limiter mechanism that moves the airbag body toward the front side of the seat when a load applied to the airbag body toward the front side of the seat during head restraint of the occupant's head exceeds a predetermined threshold value, The force limiter mechanism includes: a movable member including a supply pipe attached to an upper end portion thereof for supplying gas ejected from the inflator to the airbag body, the movable member having a lower end portion supported by the seat back frame so as to be rotatable about an axial direction of the seat width direction; an energy absorbing portion that is provided between the supply pipe or the movable member and the seat back frame and that absorbs energy when the load exceeds a predetermined threshold while allowing the movable member to rotate toward the seat front side; A seat-mounted airbag device having a seat.

2. An airbag body having: front and rear chambers which are deployed to the side of an occupant's head toward the front side of the seat by gas ejected from an inflator which is activated when a vehicle collision is detected or predicted; and a tip chamber which is deployed inward in the seat width direction from the front end of the front and rear chambers and is positioned on the front side of the seat of the occupant's face; the airbag body and the seat back frame are connected to each other by a force limiter mechanism that moves the airbag body toward the front side of the seat when a load applied to the airbag body toward the front side of the seat during head restraint of the occupant's head exceeds a predetermined threshold value, The force limiter mechanism includes: a supply pipe connected to the inflator fixed to the seat back frame and supplying gas ejected from the inflator to the airbag body; a tube having an excess length for accommodating the supply pipe therein and connecting the inflator and the airbag body; A reaction plate provided at a seat rear end of the airbag body; an energy absorbing portion provided between the reaction plate and the seat back frame, which absorbs energy when the load exceeds a predetermined threshold and allows the reaction plate to move toward the front side of the seat; A seat-mounted airbag device having a seat.

3. The force limiter mechanism includes:

3. The seat-mounted airbag device according to claim 1, wherein the airbag body is configured to be deactivated by a load toward the front side of the seat when the airbag body is inflated and deployed.

4. The energy absorbing portion includes a plate that absorbs energy by plastic deformation, 4. The seat-mounted airbag device according to claim 3, wherein the plate has a thickness in a portion of its deformation region that is set to be thicker than the thickness in other portions of its deformation region so as to be able to withstand a load toward the front side of the seat when the airbag body is inflated and deployed.

5. The force limiter mechanism comprises:

4. The seat-mounted airbag device according to claim 3, further comprising an actuator that activates the force limiter mechanism when the load exceeds a predetermined threshold value.

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