Patent Description:
Hereinafter, in the present application, "up" and "above" refer to a head region direction of an occupant seated in a regular position in a vehicle seat, and "down" and "below" refer to a foot direction of the occupant. Furthermore, "front" and "forward" refer to a front surface direction of the occupant seated in the regular position, while "rear" and "rearward" refer to a back surface direction of the occupant. Furthermore, "left" and "left side" refer to a left-hand direction of the occupant seated in the regular position, while "right" and "right side" refer to the right-hand direction of the occupant. Note that "regular position" of the vehicle seat refers to a seating position along which the entire back of the occupant is in contact with a seatback included on the vehicle seat at a center position in a left-right direction of a seat cushion included on the vehicle seat.

In recent years, for example, airbag devices have been proposed in which a hood-shaped (shell-shaped) airbag ejects from a vehicle seat to cover and protect a head region of an occupant and a side portion of a shoulder region, upper arm region, and chest region of the occupant in the event of a vehicle collision (for example, Patent Documents <NUM> and <NUM>).

The airbag devices include an airbag device in which a hood-shaped airbag is expanded and deployed by a single inflator (for example, Patent Document <NUM>) and an airbag device in which a left side portion and right side portion of the airbag are expanded and deployed by separate inflators (for example, Patent Document <NUM>). From Patent Document <NUM> it is known another side-impact airbag system having an inner airbag that is supplied with gas and inflates and deploys in an inner side in a vehicle width direction for a seating occupant on a driver's seat. D3 discloses an airbag device, that protects at least a side portion of a shoulder region, upper arm region, and chest region for an occupant seated on a vehicle seat whereby the airbag has a pair of side part protection chambers that are housed on at least both left and right sides of the vehicle seat, the side part protection chambers, when expanded and deployed, expand and deploy forward independently on both left and right sides of the vehicle seat, and a pair of inflators are provided so as to provide gas to the respective side part protection chambers of the airbag, and are controlled so as to be ignited at different timing.

In the airbag device using a single inflator to expand and deploy a hood-shaped airbag, a left side portion and right side portion of the airbag are simultaneously expanded and deployed. Furthermore, the basis of the airbag device using separate inflators to expand and deploy the left side portion and right side portion of the airbag is that the separate inflators are ignited at the same timing to simultaneously expand and deploy the left side portion and right side portion of the airbag. Thus, simultaneous expansion and deployment of the left side portion and right side portion of the airbag is based on the premise that the occupant is seated in the vehicle seat in a regular state. The "regular state" as referred to herein is not limited to being seated in a regular position, but also includes being seated in the left-right direction within a predetermined distance from the regular position, or being moved in the left-right direction, forward or diagonally forward within a predetermined distance from the regular position due to a collision or the like.

However, the occupant may not always be seated in the vehicle seat in the regular state, and may be seated offset in the left-right direction from the regular state. Furthermore, even when the occupant is seated in the vehicle seat in the regular state, the occupant may move from the regular state in the left-right direction, forward or diagonally forward before the airbag expands and deploys, due to a vehicle collision or the like.

For example, as illustrated in <FIG>, when an occupant <NUM> is seated on a right side of a seat, and when a left side portion and right side portion of an airbag <NUM> simultaneously expand and deploy, a right side airbag portion 3a may get caught on a head region 2a of the occupant <NUM> (see <FIG>). In this case, the airbag <NUM> does not reliably expand and deploy, and the head region 2a of occupant <NUM> and a side portion 1b [sic] of a shoulder region, upper arm region, and chest region of the occupant <NUM> cannot be properly protected, as illustrated in <FIG>. Note that in <FIG>, <NUM> indicates a vehicle seat, 1a indicates a seat cushion, 1b indicates a seatback, and 1c indicates a headrest.

A problem to be solved by the present invention is that if left and right inflators are simultaneously ignited, the airbag may not reliably expand and deploy when an occupant is seated offset in a left-right direction from a regular state, or when the occupant moves in the left-right direction or the like from the regular state.

In view of the foregoing, an object of the present invention is to ensure that an airbag expands and deploys even when an occupant is seated offset in a left-right direction from a regular state, or when the occupant moves in the left-right direction or the like from the regular state due to a collision or the like.

The present invention is an airbag device including an airbag that protects at least a side portion of a shoulder region, upper arm region, and chest region of an occupant seated on a vehicle seat and an inflator that supplies gas to the airbag, and has the following configurations as main features.

The airbag has a pair of side part protection chambers that are housed on at least both left and right sides of the vehicle seat.

Furthermore, the side part protection chambers, when expanded and deployed, expand and deploy forward independently from both the left and right sides of the vehicle seat.

Furthermore, a pair of inflators are provided so as to provide gas to the respective side part protection chambers of the airbag, and are controlled so as to be ignited at a different timing.

The airbag device of the present invention ignites an inflator at the following timing.

The inflator disposed on the right side of the vehicle seat is ignited at an earlier timing than the inflator disposed on the left side.

Furthermore, the time difference in ignition timings between the inflators to be ignited first and the inflator to be ignited later depends on the degree of offset.

The airbag may further include a head region protection chamber that expands and deploys from above the side part protection chamber that protects the side portion of the occupant so as to wrap around an upper end edge portion of a seatback of the vehicle seat in the vicinity of the upper end edge portion to protect the head region of the occupant.

Alternatively, the pair of side part protection chambers of the airbag may have a shape in which the distance between the occupant side surfaces narrows toward the front when viewed from above during expansion and deployment.

Alternatively, the pair of side part protection chambers of the airbag may further include an extension chamber leading from the side part protection chamber that protects the side portion of the occupant to the front of the occupant.

Alternatively, the pair of side part protection chambers of the airbag may be physically connected via a coupling part.

In the airbag device of the present invention, the pair of side part protection chambers are arranged separated but facing each other on both the left and right sides of the vehicle seat, and are housed in the vehicle seat in a rolled state or folded state. This is a vehicle seat of the present invention.

The inflator disposed on the right side of the vehicle seat and the inflator disposed on the left side are ignited at the same timing.

The inflator on the collision side of the vehicle seat is ignited at an earlier timing than the inflator on the opposite side in the left-right direction from the collision side.

The inflator on the collision side of the vehicle seat is ignited at an earlier timing than the inflator on the opposite side in the left-right direction from the collision direction.

Control of the inflator ignition timing is controlled by an ECU (Electronic Control Unit), which controls airbag expansion and deployment based on signals output from a plurality of various sensors mounted in the vehicle.

In the present invention, even if a seating position of an occupant in a vehicle seat is offset in the left-right direction from the regular state, or if the occupant moves to an offset position from the regular state due to a collision or the like, an airbag portion on the offset side will not catch on the occupant in an initial stage of expansion and deployment.

In the present invention, an airbag can be reliably deployed even if a seating position of an occupant in the vehicle seat is offset in the left-right direction from the regular state, or if the occupant moves to an offset position from the regular state due to a collision or the like. Therefore, at least a side portion of a shoulder region, upper arm region, and chest region of an occupant can be properly covered, thereby improving safety.

For example, if the seating position of an occupant in a vehicle seat is offset in a left-right direction from a regular state, igniting left and right inflators at the same timing may prevent an airbag from reliably expanding and deploying.

The present invention solves the aforementioned problem by optimally controlling ignition timings of a pair of inflators that supply gas to the left side and right side part protection chambers of an airbag having a pair of side part protection chambers housed on at least both left and right sides of a vehicle seat.

Embodiments of the present invention will be described hereinafter using <FIG>.

An airbag device <NUM> of the present invention includes, for example, an airbag <NUM> that covers a head region 2a and a side portion 2b of a shoulder region, upper arm region, and chest region of an occupant <NUM> seated in a vehicle seat <NUM>, and a cylindrical inflator <NUM> that ejects gas into the airbag <NUM> from an outer side surface thereof.

The vehicle seat <NUM> has a seat cushion 1a and a seatback 1b, and a headrest 1c is integrally formed in an upper part of the seatback 1b (see <FIG>) or separately mounted (see <FIG>). The seat cushion 1a and seatback 1b are supported by a frame 1d.

The airbag <NUM> has a shape where a left-right direction is longer than an up-down direction. Furthermore, two identical sheets 12a, 12b are overlaid and stitches <NUM>, <NUM> are formed at an outer peripheral portion and center portion in the left-right direction to form expandable chambers 12c on both left and right sides.

In other words, the stitch <NUM> in the center portion in the left-right direction physically connects the left and right chambers 12c, and the stitch <NUM> is referred to as a coupling part 12d hereinafter.

Furthermore, the left and right chambers 12c are demarcated by a stitch <NUM> into side part protection chambers 12ca positioned on left and right end portion sides of the airbag <NUM>, and a head region protection chamber 12cb positioned on the center portions of the left and right portions of the airbag <NUM>.

In <FIG>, a ventilating port <NUM> is formed between the side part protection chambers 12ca and head region protection chamber 12cb by not allowing an end side of the stitch <NUM> to connect with the stitch <NUM> on the outer peripheral portion. When expansion of the side part protection chamber 12ca is completed, the ventilating port <NUM> supplies gas to the head region protection chamber 12cb by gas flowing from the side part protection chambers 12ca to the head region protection chamber 12cb.

Furthermore, in <FIG>, an insertion portion 12e for the inflator <NUM> is formed in each of the left and right chambers 12c of the airbag <NUM>, and the inflators <NUM> are inserted into insertion portions 12e. Furthermore, gas can be supplied from the inflators <NUM> to the left and right chambers 12c, such that the left and right chambers 12c have a fluidly independent configuration.

Furthermore, in <FIG>, the insertion portion 12e is provided with a gas guide <NUM> formed in a substantial Y-shape. The gas guide <NUM> is provided with an inlet port 18a where the inflator <NUM> is inserted, a first outlet port 18b that guides gas ejected from the inflator <NUM> into the side part protection chambers 12ca, and a second outlet port 18c that guides the gas into the head region protection chamber 12cb. A cross-sectional area of the first outlet port 18b and second outlet port 18c are appropriately determined based on an amount of gas supplied to the side part protection chambers 12ca and head region protection chamber 12cb.

The airbag device <NUM> is housed in the vehicle seat <NUM> in a rolled state or state folded into a bellows shape, and in this case, the side part protection chambers 12ca are arranged separated but facing each other on both left and right sides of the vehicle seat <NUM>, for example, the seatback 1b.

In the case of a vehicle seat <NUM> of the present invention in which the airbag device <NUM> of the present invention is housed in the aforementioned state, for example, in the event of a collision, a collision signal is input from a collision detection sensor (not shown) to an ECU (not shown), and an ignition signal is output from the ECU to the inflator <NUM>. Upon receiving the ignition signal, the inflator <NUM> ejects gas to expand and deploy the side part protection chambers 12ca forward independently from both left and right sides of the vehicle seat <NUM>. The collision detection sensor may be a satellite sensor (not shown) used for normal airbag deployment control, an acceleration sensor in the ECU described above, or the like.

Furthermore, in conjunction with the expansion and deployment of the side part protection chamber 12ca, the head region protection chamber 12cb expands and deploys from above the side part protection chambers 12ca so as to wrap around an upper end edge portion of the seatback 1b in the vicinity of the upper end edge portion.

The airbag device <NUM> of the present invention is not limited to the configuration illustrated in <FIG> but can also include a guide 12f on an upper center portion of the airbag <NUM>, as illustrated in <FIG>. The guide 12f has two sub-regions <NUM> fa including an expansion region 12fb and a non-expansion region 12fc, respectively, with the coupling part 12d interposed therebetween. Furthermore, in an early stage expansion and deployment of the airbag <NUM>, the two expansion regions 12fb expand before the chamber 12c, pulling the airbag <NUM> away from the seatback 1b and ensuring that the chamber 12c can expand.

The airbag device <NUM> described in <FIG> and <FIG> includes the coupling part 12d that physically connects the pair of chambers 12c that are disposed on both left and right sides of the seatback 1b. The chamber 12c has both the side part protection chambers 12ca and the head region protection chamber 12cb.

In contrast, the airbag device <NUM> illustrated in <FIG> and <FIG> does not have the coupling part 12d that physically connects the pair of chambers 12c, and the chamber 12c does not have the head region protection chamber 12cb. In other words, the airbag device <NUM> of the present invention illustrated in <FIG> and <FIG> includes two airbags <NUM> having the chamber 12c provided only with the side part protection chambers 12ca and an inflator (not shown in <FIG> and <FIG>) that supplies gas to the chamber 12c.

In a rolled state or a state folded into a bellows shape, the airbags <NUM> are housed in the seatback 1b of the vehicle seat <NUM>, as illustrated in <FIG>, so as to be separated but facing each other (vehicle seat of present invention).

Furthermore, when viewed, for example, from above in a state where expansion and deployment due to a collision or the like is completed, the airbag <NUM> is formed in a shape where an interval D between surfaces <NUM> opposing the side portion 2b of the occupant <NUM> becomes narrower toward the front of the vehicle, as illustrated in <FIG>.

In the case of the airbag <NUM> having this shape, when an impact during a frontal collision is large, the amount of forward movement of the occupant <NUM> is large. However, the interval D between the surfaces <NUM> of the airbag <NUM> becomes narrower toward the front of the vehicle. Therefore, a force of restraining the occupant <NUM> increases toward the front of the vehicle, and thus more reliable restraint is possible (see <FIG>).

On the other hand, when the impact during a frontal collision is small, the amount of forward movement of the occupant <NUM> is small, and the interval D between the surfaces <NUM> of the airbag 12d becomes wider. Therefore, a force of restraining the occupant <NUM> decreases, and thus safety increases (see <FIG>).

In <FIG> and <FIG>, <NUM> is a tension cloth that is stowed across the seatback 1b to the seat cushion 1a. During expansion and deployment of the airbag <NUM>, the tension cloth <NUM> is stretched from the seatback 2b [sic] to the seat cushion 1a by cleaving open a skin of the vehicle seat <NUM>, and retains a surface <NUM> of the airbag <NUM> on an opposite side from the surface <NUM>.

The airbag device <NUM> illustrated in <FIG> is the airbag device <NUM> illustrated in <FIG> and <FIG> further provided with an extension chamber 12i, which is supplied with gas from the chamber 12c via an inner vent <NUM>. The extension chamber 12i is a front surface 12j of the chamber 12c when only the chamber 12c is expanded and deployed (see <FIG>). Thereafter, when the extension chamber 12i is also expanded and deployed, the extension chamber 12i is provided at a position opposing the head region 2a of the occupant <NUM>. (See <FIG>).

In the case of the airbag device <NUM> having the extension chamber 12i, for example, in the event of a frontal collision, the pair of chambers 12c first expand and deploy to restrain the side portion 2b of the occupant <NUM>, as illustrated in <FIG>. Thereafter, each extension chamber 12i supplied with gas through each chamber 12c expands and deploys in front of the head region 2a of the occupant <NUM> to restrain the head region 2a of occupant <NUM>, as illustrated in <FIG>. Therefore, the airbag <NUM> can restrain the head region 2a of the occupant <NUM> more reliably than the airbag <NUM> illustrated in <FIG> and <FIG>, thereby achieving even higher occupant restraining performance.

The internal pressure of the extension chamber 12i can be appropriately adjusted adjusting the diameter of the inner vent <NUM>. Furthermore, the extension chamber 12i may also not be a delayed chamber that is illustrated in <FIG>, but may be configured to expand and deploy almost simultaneously with the chamber 12c.

The airbag device <NUM> of the present invention illustrated in <FIG> has the extension chamber 12i on a forward side of the surface <NUM> of the chamber 12c opposing the side portion 2b of the occupant <NUM> during expansion and deployment.

Furthermore, in addition to the inner vent <NUM> described above, the extension chamber 12i illustrated in <FIG> has an outer vent <NUM> to discharge gas inside the extension chamber 12i. The outer vent <NUM> is provided at a position that satisfies the following two conditions:.

In the case of the airbag device <NUM> with the extension chamber 12i, for example, before the occupant <NUM> moves forward immediately after the airbag <NUM> expands and deploys during a frontal collision, the outer vent <NUM> is closed as illustrated in <FIG>. Therefore, the airbag <NUM> can maintain a high internal pressure to strongly restrain the side portion 2b of the occupant.

Thereafter, when the occupant <NUM> moves forward, and when the extension chamber 12i is pushed forward by the head region 2a, the outer vent <NUM> is open such that gas escapes, causing the internal pressure of the chamber 12c to decrease, as illustrated in <FIG>. Therefore, the injury value to the occupant <NUM> is reduced, and thus safety is improved.

A method of igniting Embodiment <NUM> of the airbag device <NUM> illustrated in <FIG> will be described below.

A feature of the present invention is that the ignition timing of the inflators <NUM> can be varied for the left and right sides depending on the seating position of the occupant <NUM> in the vehicle seat <NUM> or the collision position.

For example, as illustrated in <FIG>, if an occupant state detection sensor (not shown) detects that the occupant <NUM> is seated in the vehicle seat <NUM> in a position offset to the right side from the regular state, the inflator <NUM> on the right side of the vehicle seat <NUM> is ignited at an earlier timing than the inflator <NUM> on the left side.

The occupant state detection sensor includes a detection apparatus capable of detecting the posture and seating position of the occupant <NUM>, such as one or more pressure sensors internally provided in the vehicle seat <NUM> or an in-vehicle monitoring camera appropriately arranged in the cabin, and detects the position and posture of the seated occupant <NUM>.

When the timing of igniting the inflator <NUM> is controlled as described above, the chamber 12c on the right side of the vehicle seat <NUM> expands and deploys before the chamber 12c on the left side of the vehicle seat <NUM>. Therefore, even if the occupant <NUM> is seated offset to the right side from the regular state at an initial stage of expansion and deployment of the airbag <NUM>, as illustrated in <FIG>, the right side chambers 12c (side part protection chambers 12ca and head region protection chamber <NUM>) will not get caught on the head region 2a or shoulder region of the occupant <NUM>.

Thereafter, as illustrated in <FIG>, the airbag <NUM> reliably expands and deploys, the head region protection chamber 12cb covers the head region 2a of the occupant <NUM> from above, and the side part protection chambers 12ca cover the side portion 2b of the shoulder region, upper arm region, and chest region to restrain lateral movement of the occupant <NUM>.

"Regular state" as referred in the present invention refers to a case where the seating position is within a range indicated by the diagonal lines in <FIG>. For example, if the seating position is within a trapezoidal range connecting points <NUM> away in the left-right direction (positions A and C in <FIG>) from the regular position indicated by B in <FIG>, and points <NUM> away in the left-right direction and <NUM> to the front (positions D and E in <FIG>). The range indicated by the diagonal lines is approximately determined based on the volume of the airbag <NUM>, the capacity of the inflator <NUM>, and the time between impact detection of an impact detection sensor and the start of ignition of the inflator <NUM>.

<FIG> describe a case where the occupant <NUM> is seated to the right side of the position indicated by "A" in <FIG>, which is offset to the right side from the regular state, but the method of the present invention when the occupant <NUM> is seated at some other position is described using <FIG>.

In this case, even if the chambers 12c on both left and right sides of the vehicle seat <NUM> simultaneously deploy, the chambers 12c will not get caught on the head region 2a of the occupant <NUM> in the initial stage of expansion and deployment and inhibit the airbag <NUM> from expanding and deploying. Therefore, the inflators <NUM> on the right side and left side of the vehicle seat <NUM> are ignited at the same timing.

In this case, if the chambers 12c on both left and right sides of the vehicle seat <NUM> simultaneously expand and deploy, the chamber 12c on the left side may get caught on the head region 2a of the occupant in the initial stage of expansion and deployment and inhibit expansion and deployment of the airbag <NUM>. Therefore, in this case, the inflator <NUM> disposed on the left side of the vehicle seat <NUM> is ignited at an earlier timing than the inflator <NUM> disposed on the right side of the vehicle seat <NUM>.

In the case, if the ECU determines that the occupant <NUM> moves to a position more to the right side than "A" in <FIG>, which is to the right side from the regular state, during expansion and deployment of the airbag <NUM> due to the collision (particularly from before the start of the expansion and deployment to the initial stage of the expansion and deployment until the airbag expands and deploys and starts to contact the occupant <NUM>), the inflator <NUM> on the right side of the vehicle seat <NUM> is ignited at an earlier timing than the inflator <NUM> on the left side.

In the case, if the ECU determines that the occupant <NUM> moves to a position more to the left side than "C" in <FIG>, which is to the left side from the regular state, during expansion and deployment of the airbag <NUM> due to the collision (particularly from before the start of the expansion and deployment to the initial stage of the expansion and deployment until the airbag expands and deploys and starts to contact the occupant <NUM>), the inflator <NUM> on the left side of the vehicle seat <NUM> is ignited at an earlier timing than the inflator <NUM> on the right side.

When one inflator <NUM> on either left or right side is ignited at an earlier timing than the inflator <NUM> on the other side, the difference in ignition timing is changed in accordance with the degree of offset.

Control of the ignition timing of the inflator <NUM> is controlled by the ECU, which controls expansion and deployment of the airbag <NUM> based on output signals from a plurality of various sensors mounted in the vehicle.

As one specific example, a table is prepared in the ECU for expanding and deploying the airbag <NUM> at an ideal timing based on the form of collision. The table stores the appropriate individual ignition timing for each inflator <NUM> based on the seating position and posture of the occupant <NUM>, form of the collision, and the like, as detected based on outputs from various sensors. The ECU determines the form of collision and the state of the occupant <NUM> (posture, position, and the like) based on output signals of the intensity, direction, and the like of the collision transmitted from the collision detection sensors and output signals indicating the seating position and posture of the occupant <NUM> transmitted from the occupant state detection sensor. Based on the determination results, the ignition timing of the second inflator <NUM> is delayed by several milliseconds to several hundred milliseconds relative to the first inflator <NUM> to be ignited first.

In the case of a typical side collision, the delay (difference) in ignition timing is preferably between a few milliseconds and a hundred milliseconds. However, the ideal ignition timing (delay, difference) varies greatly depending on the form of collision, and therefore, the ignition timing can be significantly varied up to a few hundred milliseconds depending on the form of collision.

In other words, the airbag device described above are preferred examples of the present invention.

Unless otherwise specified in the specification of the present application, there are no limitations to the shape, size, configuration, arrangement, and the like of the components illustrated in the attached drawings in the present invention. Furthermore, expressions and terms used in the specification of the present application are for the purpose of description and are not limiting unless otherwise specified.

Furthermore, the airbags <NUM> illustrated in <FIG> and <FIG> are provided with gas guide <NUM>. However, the gas guide <NUM> may be omitted so long as the gas from the inflator <NUM> is reliably guided to the side part protection chambers 12ca, head region protection chamber 12cb, and expansion region 12fb.

Furthermore, the airbag devices <NUM> that protect the head region 2a of the occupant <NUM> and the side portion 2b of the shoulder region, upper arm region, and chest region of the occupant <NUM> are described in the embodiments illustrated in <FIG> and <FIG>. However, the present invention may be applied to an airbag device that protects the head region 2a of the occupant <NUM> and the side portion 2b of the abdomen region and waist region of the occupant <NUM> in addition to the shoulder region, upper arm region, and chest region. Furthermore, in the case of the embodiments illustrated in <FIG>, the chamber 12c (side part protection chambers 12ca) may restrain not only the side portions 2b of the shoulder region, upper arm region, and chest region of the occupant <NUM>, but also the side portion 2b of the abdomen region and waist region of the occupant <NUM>.

Furthermore, in Embodiment <NUM> to Embodiment <NUM> of the airbag device <NUM> illustrated in <FIG>, the tension cloth fabric <NUM> retains the surface <NUM> on the opposite side of the airbag <NUM> from the occupant <NUM>. However, if the movement of the occupant <NUM> can be restrained in the event of a collision or the like, the tension cloth <NUM> may be eliminated.

Furthermore, the airbag device <NUM> of the present invention is not limited to mounting the side part protection chambers 12ca to an outer side of the frame 1d in the left-right direction when housing the airbag <NUM> in, for example, the seatback 1b of the vehicle seat <NUM>, and may be mounted to an inner side of the frame 1d in the left-right direction. Furthermore, the inflator <NUM> may also be mounted on either the inner side or outer side of the frame 1d in the left-right direction.

Claim 1:
An airbag device (<NUM>), comprising:
an airbag (<NUM>) that protects at least a side portion of a shoulder region, upper arm region, and chest region for an occupant (<NUM>) seated on a vehicle seat (<NUM>); and
an inflator (<NUM>) that supplies gas to the airbag (<NUM>); wherein
the airbag (<NUM>) has a pair of side part protection chambers (12ca) that are housed on at least both left and right sides of the vehicle seat (<NUM>),
the side part protection chambers (12ca), when expanded and deployed, expand and deploy forward independently on both left and right sides of the vehicle seat (<NUM>), and
a pair of inflators (<NUM>) are provided so as to provide gas to the respective side part protection chambers (12ca) of the airbag (<NUM>), and are controlled so as to be ignited at different timing, characterized in that
when an occupant state detection sensor detects that the seating position of an occupant (<NUM>) is offset to the left side of a regular state, the inflator (<NUM>) disposed on the left side of the vehicle seat (<NUM>) is ignited at an earlier timing than the inflator (<NUM>) disposed on the right side, or
when an occupant state detection sensor detects that the seating position of an occupant (<NUM>) is offset to the right side of a regular state, the inflator (<NUM>) disposed on the right side of the vehicle seat (<NUM>) is ignited at an earlier timing than the inflator (<NUM>) disposed on the left side, wherein
the time difference in ignition timings between the inflators (<NUM>) to be ignited first and the inflator (<NUM>) to be ignited later depends on the degree of offset.