Airbag unit

An airbag unit includes a seat, a pair of side airbags, a seat state detector, and an airbag deployment controller. The seat is reversely rotatable in a front-rear direction of a vehicle. The pair of side airbags are expansive and deployable, and incorporated in the seat on respective sides of the seat in a width direction of the vehicle. The seat state detector detects a rearward-oriented state of the seat, i.e., a state in which the seat is rearward-oriented in the front-rear direction. The airbag deployment controller performs a deployment control of the pair of side airbags, on a condition that the seat state detector detects the rearward-oriented state of the seat. The airbag deployment controller performs the deployment control in a reverse sequence from a deployment control in a frontward-oriented state of the seat, i.e., a state in which the seat is frontward-oriented in the front-rear direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from Japanese Patent Application No. 2016-055896 filed on Mar. 18, 2016, the entire contents of which are hereby incorporated by reference.

BACKGROUND

The technology relates to an airbag unit. Specifically, the technology relates to an airbag unit that provides protection for an occupant, with a method of a deployment control of a side airbag unit, even when a driver's seat or a navigator's seat is rearward-oriented in a front-rear direction.

A side airbag unit has been known as an airbag unit that provides protection for an occupant against a collision when a vehicle is collided from sideward. The side airbag unit may be incorporated in a backrest of a seat. As illustrated inFIG. 6, bucket seats100may be disposed in a compartment of a vehicle. The bucket seats100may include a driver's seat101and a navigator's seat102. A pair of side airbag units103R and103L may be provided in the driver's seat101, on right and left sides of the driver's seat101. A pair of side airbag units104R and104L may be provided in the navigator's seat102, on right and left sides of the navigator's seat102. The side airbag units103R,103L,104R, and104L each may include, although undepicted, an airbag in a bag shape, an inflator, and a case. The inflator may generate gas that causes the airbag to expand. The case may accommodate the airbag and the inflator.

If a side collision should occur on side of the vehicle on which the driver's seat is disposed, the inflators of the side airbag units103R and104R may be selectively ignited. This causes instant gas supply from the inflators to the airbags. Hence, it is possible to protect occupants from the side collision of the vehicle, and to prevent an occupant seated on the driver's seat from colliding with an occupant seated on the navigator's seat.

The side airbag units103R,103L,104R, and104L may expand and deploy upon the occurrence of the side collision in the following order. First, a side collision sensor on right side of the vehicle may detect the side collision on the right side of the vehicle. This causes expansion and deployment of the side airbag units103R and104R on the right sides of the seats101and102. Hence, it is possible to prevent the occupant seated on the driver's seat101from colliding with an inner surface of a side wall of the vehicle, and to prevent the occupant seated on the driver's seat101from colliding with the occupant seated on the navigator's seat102.

Next, a rollover sensor of the vehicle may detect a rollover of the vehicle due to the side collision. This causes expansion and deployment of the side airbag units103L and104L on left sides of the seats101and102. Hence, it is possible to prevent the occupant from colliding with an protruding object inside the compartment of the vehicle, and to prevent the occupant seated on the driver's seat101from colliding with the occupant seated on the navigator's seat102. For example, reference is made to Japanese Unexamined Patent Application Publication (JP-A) No. 2003-312341.

SUMMARY

As described, when the side collision sensor on the right side of the vehicle detects the side collision on the right side of the vehicle, the side airbag units103R and104R on the right sides of the seats101and102may expand and deploy. Thereafter, when the rollover sensor of the vehicle detects the rollover of the vehicle due to the side collision, the side airbag units103L and104L on the left sides of the seats101and102may expand and deploy.

In short, the existing side airbag units103R,103L,104R, and104L give priority to the expansion and deployment of the side airbag units on side of the vehicle on which the side collision has occurred. Thus, the occupant may be protected against the collision with the inner surface of the side wall of the vehicle.

However, the existing side airbag units103R,103L,104R, and104L lack a configuration that may provide protection for the occupant on an assumption that the vehicle may run with the driver's seat101or the navigator's seat102rotated toward rear seats of the vehicle, in face-to-face relation to the rear seats.

With the driver's seat101or the navigator's seat102thus rotated toward the rear seats of the vehicle, when, for example, the side collision sensor on the right side of the vehicle detects the side collision on the right side of the vehicle, the side airbag unit103R on the right side of the driver's seat101may expand and deploy. In this case, there is a disadvantage of difficulty in providing appropriate protection for the occupant against the collision with the inner surface of the side wall of the vehicle. The collision of the occupant with the inner surface of the side wall of the vehicle is considered to possibly cause severest damage to the occupant.

It is desirable to provide an airbag unit that makes it possible to provide appropriate protection for an occupant.

An aspect of the technology provides an airbag unit that includes a seat, a pair of side airbags, a seat state detector, and an airbag deployment controller. The seat is disposed in a vehicle, and capable of shifting between a first state being a state in which the seat is frontward-oriented in a front-rear direction of the vehicle reversely rotatable in a front-rear direction of a vehicle and a second state being a state in which the seat is rearward-oriented in the front-rear direction of the vehicle. The pair of side airbags are expandable and deployable, and disposed in the seat on respective sides of the seat in a width direction of the vehicle. The seat state detector detects whether the seat is in the first state or the second state. The airbag deployment controller performs a deployment control of the pair of side airbags, on a condition that the seat state detector detects the rearward-oriented state of the seat. The airbag deployment controller performs a first deployment control to the pair of side airbags, on a condition that the seat state detector detects that the seat is in the first state, and performs a second deployment control to the pair of side airbags, on a condition that the seat state detector detects that the seat is in the second state. The second deployment control is in a reverse sequence from the fits deployment control.

The pair of side airbags may be substantially disposed in bilateral symmetry with respect to a center line in the width direction of the vehicle.

The pair of side airbags may be expandable and deployable so as to be identical in shape with each other.

A distance from a center of the seat in the width direction of the seat in the first state to an inner surface of a side wall of the vehicle may be equal to a distance from the center of the seat in the width direction of the seat in the second state to the inner surface of the side wall of the vehicle.

DETAILED DESCRIPTION

In the following, some preferred implementations of the technology are described in detail with reference to the accompanying drawings. Note that in the following description of the implementations, the same members are denoted basically with the same reference numerals to avoid any redundant description.

FIGS. 1A and 1Bare perspective views of an inside of a compartment of a vehicle1according to an implementation, as viewed from left frontward.FIG. 2is a block diagram that summarizes a control of the vehicle1of the implementation.

Referring toFIG. 1A, the vehicle1may be a wagon type vehicle provided with three-row seats arranged in a front-rear direction of the vehicle1. The vehicle1may include a driver's seat2on right side of a first row, a navigator's seat3on left side of the first row, a right seat4and a left seat5of a second row, and a right seat6and a left seat7of a third row. Referring toFIG. 1B, the vehicle1may have a function of automatic operation. For example, under a certain condition during the automatic operation, the vehicle1may run, with the driver's seat2and the navigator's seat3of the first row rotated 180° and faced with the right seat4and the left seat5of the second row.

Referring toFIG. 2, a vehicle controller10may be coupled to an input unit11, a vehicle exterior environment recognition unit12, an airbag unit13, a drive unit14such as an engine, a steering unit15such as a steering wheel, a braking unit16, and other undepicted control equipment including a notification unit (undepicted) such as a multi function display. The input unit11may include, for example, a push-button switch or a touch panel that may be operated by an occupant. The vehicle exterior environment recognition unit12may include, for example, a stereo camera or radar that may recognize exterior environment of the vehicle1. The airbag unit13may provide protection for the occupant against impact in an event of, for example, a side collision of the vehicle1. The drive unit14may serve as a power source that may allow the vehicle1to run. The steering unit15may be provided for steering of the vehicle1. The braking unit16may perform deceleration and stopping of the vehicle1.

The vehicle controller10may be, for example, an electronic control unit (ECU) that may include, for example, a central processing unit (CPU), read only memory (ROM), and random access memory (RAM), and execute processing such as various kinds of calculations for a vehicle control.

The vehicle controller10may switch manual operation and automatic operation, on a basis of an instruction from the input unit11. The manual operation may be a normal operation mode in which a driver may perform driving operation, whereas the automatic operation may be an operation mode in which the vehicle controller10may automatically perform driving. During the automatic operation, the vehicle controller10may execute various kinds of calculation, on a basis of information supplied from the vehicle exterior environment recognition unit12and other units, and constantly monitor a current running state, the exterior environment, and other situations. The vehicle controller10may control the braking unit16, the drive unit14, and the steering unit15, to perform appropriate automatic operation, in accordance with current situations. Thus, the vehicle controller10may have the function of the automatic operation, and automatically perform the driving operation of the vehicle1.

The airbag unit13may include, as its principal components, a curtain bag, an inflator, and a housing box, for example. The inflator may supply gas to the curtain bag. The housing box may accommodate the curtain bag in a folded state and the inflator. Details of these components are described later. The airbag unit13may be controlled by the vehicle controller10, and allow the curtain bag at a desired location to expand and deploy as appropriate, on a basis of signals from various collision sensors, to provide protection for the occupant against, for example, impact of a collision.

Note that the airbag unit13may be appropriately disposed at various locations in the vehicle1, and include, for example, an airbag unit disposed at the steering wheel or an instrument panel, and a curtain airbag unit disposed on a roof side rail. In the following, description is given in detail of pairs of side airbag units that are disposed in the driver's seat2and the navigator's seat3on the first row, on right and left sides of the respective seats2and3in a width direction of the vehicle1.

FIG. 3Ais a perspective view of the driver's seat2of the vehicle1according to this implementation, as viewed from right frontward.FIG. 3Bis a schematic plan view of seating arrangement of the vehicle. Note that the following description is given of a configuration of the driver's seat2, but a configuration of the navigator's seat3may be similar to that of the driver's seat2. The following description regarding the driver's seat2may therefore apply to the configuration of the navigator's seat3, and description thereof is omitted here.

Referring toFIG. 3A, the driver's seat2may include a seat cushion21, a backrest22, and a headrest23. The seat cushion21may be a part on which the occupant may be seated. The backrest22may extend upward from a rear part of the seat cushion21, and support a back of the occupant. The headrest23may be disposed at an upper end of the backrest22.

The seat cushion21may be movable along an undepicted slide rail. The slide rail may be disposed on, for example, a floor panel of the vehicle1, and extend in the front-rear direction. This allows the seat cushion21to move manually or automatically in the front-rear direction. The backrest22may be supported, by an undepicted hinge mechanism, to be tiltable in the front-rear direction. The hinge mechanism may be disposed on, for example, the floor panel of the vehicle1. This allows for adjustment of a tilting angle of the backrest22.

The driver's seat2may be 180° reversely rotatable in a horizontal plane by, for example, an electric hydraulic device or an electric motor that may be disposed below the seat cushion21. After being reversely rotated 180°, the driver's seat2may move manually or automatically along the slide rail as mentioned above.

As illustrated in the figures, a pair of side airbag units24R and24L may be disposed inside the backrest22of the driver's seat2, on the right and left sides of the driver's seat2. The side airbag unit24R may be disposed inside the backrest22, in vicinity of a side surface of the backrest22that may face an inner surface32of a side wall of the vehicle1. The side airbag unit24R may be disposed, for example, about10cm to20cm below from the upper end of the backrest22. The side airbag unit24L may be disposed inside the backrest22, in vicinity of a side surface of the backrest22that may face the navigator's seat3of the vehicle1. The side airbag unit24L may be disposed, for example, about 10 cm to 20 cm below from the upper end of the backrest22. In other words, the side airbags24R and24L may be disposed in bilateral symmetry in the width direction of the vehicle1with respect to a center line of the backrest22denoted by an alternate long and short dash line25.

As described, the side airbag units24R and24L may respectively include curtain bags26R and26L. In one specific but non-limiting implementation, when the side collision on a right side surface of the vehicle1is detected, the curtain bag26R may expand and deploy first, and thereafter, the curtain bag26L may expand and deploy. The first expansion and deployment of the curtain bag26R makes it possible to provide protection for the occupant against a collision of the occupant with the inner surface32of the side wall of the vehicle1. The collision of the occupant with the inner surface32of the side wall of the vehicle1is considered to possibly cause severest damage to the occupant. The slightly delayed expansion and deployment of the curtain bag26L makes it possible to prevent the occupants from colliding with one another.

As described later in detail, with the driver's seat2reversely rotated 180° in the horizontal plane, when the side collision on the right side surface of the vehicle1is detected, the curtain bag26L may expand and deploy first. The curtain bag26L may be disposed on side on which the inner surface32of the side wall of the vehicle1is disposed, with the driver's seat2rotated 180°. The curtain bags26R and26L may expand and deploy in identical shapes. The curtain bags26R and26L may expand and deploy at bilaterally symmetrical positions with respect to the center line25of the backrest22in the width direction, in lateral vicinity of the driver's seat2. With this configuration, the curtain bag26L may withstand a collision of the curtain bag26L with the inner surface32of the side wall of the vehicle1, as with the curtain bag26R. This makes it possible to provide appropriate protection for the occupant against the collision of the occupant with the inner surface32of the side surface of the vehicle1.

Referring toFIG. 3B, the navigator's seat3may include a pair of side airbag units27R and27L, as with the driver's seat2. The pair of side airbag units27R and27L may be disposed inside the backrest22, on the right and left sides of the navigator's seat3in the width direction of the vehicle1. The driver's seat2may be, for example, 180° reversely rotatable in the front-rear direction, with a center2A of the seat cushion21serving as an axis of rotation. Also, the navigator's seat3may be, for example, 180° reversely rotatable in the front-rear direction, with a center3A of the seat cushion31serving as an axis of rotation. Note that in one alternative but non-limiting implementation, the driver's seat2and the navigator's seat3may be 180° reversely rotatable while being slidable inward of the vehicle1, and positions of the centers2A and3A of the seat cushions21and31after the rotation may coincide with positions of the centers2A and3A of the seat cushions21and31before the rotation.

With this configuration, in the driver's seat2, a distance from the center2A of the seat cushion21to the inner surface32of the side wall of the vehicle1may be kept unchanged before and after the rotation. In the navigator's seat3, a distance from the center3A of the seat cushion31to the inner surface32of the side wall of the vehicle1may be kept unchanged before and after the rotation. In other words, the distance from the center2A of the seat cushion21of the driver's seat2in a frontward-oriented state to the inner surface32of the side wall of the vehicle1may be equal to the distance from the center2A of the seat cushion21of the driver's seat2in a rearward-oriented state to the inner surface32of the side wall of the vehicle1. The distance from the center3A of the seat cushion31of the navigator's seat3in the frontward-oriented state to the inner surface32of the side wall of the vehicle1may be equal to the distance from the center3A of the seat cushion31of the navigator's seat3in the rearward-oriented state to the inner surface32of the side wall of the vehicle1. The frontward-oriented state is a state in which the driver's seat2or the navigator's seat3is frontward-oriented in the front-rear direction, whereas the rearward-oriented state is a state in which the driver's seat2or the navigator's seat3is rearward-oriented in the front-rear direction. Accordingly, there is little change, before and after the rotation, in a distance from the occupant who is seated on the driver's seat2or the navigator's seat3to an undepicted curtain airbag unit. This makes it possible for the curtain airbag unit to provide appropriate protection for the head or other parts of the occupant.

FIG. 4is a block diagram that summarizes a control of the side airbag units24R,24L,27R, and27L of the driver's seat2and the navigator's seat3.FIG. 5is a flowchart that illustrates control operation of the side airbag units24R,24L,27R, and27L of the driver's seat2and the navigator's seat3. Note thatFIGS. 4 and 5illustrate solely the side airbag units24R,24L,27R, and27L out of the airbag units included in the airbag unit13denoted by the broken line inFIG. 2.

Referring toFIG. 4, the side airbag units24R,24L,27R, and27L may be controlled by the vehicle controller10. To the vehicle controller10, the following may be coupled: a vehicle right-side collision sensor41; a vehicle left-side collision sensor42; a driver's-seat state detection sensor43; a navigator's-seat state detection sensor44; a right inflator45R and a left inflator45L of the driver's seat2; and a right inflator46R and a left inflator46L of the navigator's seat3. The vehicle right-side collision sensor41may detect the side collision on the right side surface of the vehicle1. The vehicle left-side collision sensor42may detect the side collision on a left side surface of the vehicle1. The driver's-seat state detection sensor43may detect a rotated position of the driver's seat2. The navigator's-seat state detection sensor44may detect a rotated position of the navigator's seat3.

Note that the driver's-seat state detection sensor43and the navigator's-seat state detection sensor44may detect, with use of, for example, a rotation angle sensor, which direction the driver's seat2and the navigator's seat3are oriented, frontward or rearward, in the front-rear direction of the vehicle1. In one alternative but non-limiting implementation, the driver's-seat state detection sensor43and the navigator's-seat state detection sensor44may detect, with use of, for example, an on-vehicle camera, which direction the driver's seat2and the navigator's seat3are oriented, frontward or rearward, in the front-rear direction of the vehicle1.

In a case in which the driver's seat2is frontward-oriented in the front-rear direction of the vehicle1, when the vehicle right-side collision sensor41detects the side collision on the right side surface of the vehicle1, the vehicle controller10may control the right inflator45R of the driver's seat2to supply the gas to the right curtain bag26R, to allow the curtain bag26R to expand and deploy. After controlling the right inflator45R, the vehicle controller10may immediately control the left inflator45L of the driver's seat2to supply the gas to the left curtain bag26L, to allow the curtain bag26L to expand and deploy.

Similarly, in a case in which the navigator's seat3is frontward-oriented in the front-rear direction of the vehicle1, when the vehicle left-side collision sensor42detects the side collision on the left side surface of the vehicle1, the vehicle controller10may control the left inflator46L of the navigator's seat3to supply the gas to the left curtain bag47L, to allow the curtain bag47L to expand and deploy. After controlling the left inflator46L, the vehicle controller10may immediately control the right inflator46R of the navigator's seat3to supply the gas to the right curtain bag47R, to allow the curtain bag47R to expand and deploy.

Meanwhile, in a case in which the driver's seat2is rearward-oriented in the front-rear direction of the vehicle1, when the vehicle right-side collision sensor41detects the side collision on the right side surface of the vehicle1, and when the driver's-seat state detection sensor43detects the driver's seat2being rotated rearward of the vehicle1, the vehicle controller10may control the left inflator45L of the driver's seat2to supply the gas to the left curtain bag26L, to allow the curtain bag26L to expand and deploy. After controlling the left inflator45L, the vehicle controller10may immediately control the right inflator45R of the driver's seat2to supply the gas to the right curtain bag26R, to allow the curtain bag26R to expand and deploy.

Similarly, in a case in which the navigator's seat3is rearward-oriented in the front-rear direction of the vehicle1, when the vehicle left-side collision sensor42detects the side collision on the left side surface of the vehicle1, and when the navigator's-seat state detection sensor44detects the navigator's seat3being rotated rearward of the vehicle1, the vehicle controller10may control the right inflator46R of the navigator's seat3to supply the gas to the right curtain bag47R, to allow the curtain bag47R to expand and deploy. After controlling the right inflator46R, the vehicle controller10may immediately control the left inflator46L of the navigator's seat3to supply the gas to the left curtain bag47L, to allow the curtain bag47L to expand and deploy.

As described, in a case in which the driver's seat2or the navigator's seat3is rearward-oriented in the front-rear direction of the vehicle1, the vehicle controller10may perform a deployment control of the side airbag units24R,24L,27R, and27L in a reverse sequence from a deployment control in a case in which the driver's seat2or the navigator's seat3is frontward-oriented in the front-rear direction of the vehicle1. This method of the deployment control allows for priority expansion and deployment of the side airbag units24R,24L,27R, and27L on side on which the inner surface32of the side wall of the vehicle1is disposed with respect to the driver's seat2or the navigator's seat3(refer toFIG. 3B), when the side collision occurs to the vehicle1. It is therefore possible to provide appropriate protection for the occupant against the collision of the occupant with the inner surface32of the side wall of the vehicle1. The collision of the occupant with the inner surface32of the side wall of the vehicle1is considered to possibly cause the severest damage to the occupant.

FIG. 5is a flowchart that illustrates the control operation of the side airbag units24R and24L of the driver's seat2in the case in which the side collision occurs to the right side surface of the vehicle1. Note that a similar flowchart may be provided regarding the control operation of the side airbag units27R and27L of the navigator's seat3, in the case in which the side collision occurs to the left side surface of the vehicle1. In the flowchart, as with the case of the driver's seat2, the side airbag unit27R or27L on side on which the inner surface32of the side wall of the vehicle1is disposed may expand and deploy first, in accordance with the orientation of the navigator's seat3. The following description regarding the control operation of the driver's seat2may therefore apply to the control operation of the navigator's seat3, and description thereof is omitted.

In step S1, the vehicle controller10may detect, with the vehicle right-side collision sensor41, the occurrence of the side collision to the right side surface of the vehicle1. When the vehicle controller10detects, with the vehicle right-side collision sensor41, the occurrence of the side collision to the right side surface of the vehicle1(YES in step S1), the flow may proceed to step S2. In step S2, the vehicle controller10may detect, with the driver's-seat state detection sensor43, the rearward-oriented state of the driver's seat2in the front-rear direction of the vehicle1. Meanwhile, when the vehicle controller10detects no occurrence of the side collision to the right side surface of the vehicle1(NO in step S1), the flow may return to step S1, and the vehicle controller10may repeat the detection of the occurrence of the side collision to the right side surface of the vehicle1, with the vehicle right-side collision sensor41.

When the vehicle controller10detects, with the driver's-seat state detection sensor43, the rearward-oriented state of the driver's seat2in the front-rear direction of the vehicle1(YES in step S2), the flow may proceed to step S3. In step S3, the vehicle controller10may control the left inflator45L of the driver's seat2to supply the gas to the left curtain bag26L, to allow the curtain bag26L to expand and deploy. Immediately thereafter, the flow may proceed to step S4, in which the vehicle controller10may control the right inflator45R of the driver's seat2to supply the gas to the right curtain bag26R, to allow the curtain bag26R to expand and deploy.

Meanwhile, when the vehicle controller10detects, with the driver's-seat state detection sensor43, no rearward-oriented state of the driver's seat2in the front-rear direction of the vehicle1(NO in step S2), the flow may proceed to step S5. In step S5, the vehicle controller10may control the right inflator45R of the driver's seat2to supply the gas to the right curtain bag26R, to allow the curtain bag26R to expand and deploy. Immediately thereafter, the flow may proceed to step S6, in which the vehicle controller10may control the left inflator45L of the driver's seat2to supply the gas to the left curtain bag26L, to allow the curtain bag26R to expand and deploy.

Thereafter, in step S7, the vehicle controller10may determine whether or not predetermined gas supply time has elapsed since a start of the expansion and deployment of the left curtain bag26L and the right curtain bag26R. When the vehicle controller10determines the elapse of the predetermined gas supply time (YES in step S7), the flow may proceed to step S8. In step S8, the vehicle controller10may control the right and left inflators45R and45L of the driver's seat2to stop the gas supply to the curtain bags26R and26L. Meanwhile, when the vehicle controller10determines that the predetermined gas supply time has not elapsed, the flow may return to step S7, and the vehicle controller10may repeat the determination on whether or not the predetermined gas supply time has elapsed.

Note that in this implementation, description is given on a case in which the side airbag units24R and24L of the driver's seat2may expand and deploy as appropriate upon the occurrence of the side collision to the right side surface of the vehicle1, whereas the side airbag units27R and27L of the navigator's seat3may expand and deploy as appropriate upon the occurrence of the side collision to the left side surface of the vehicle1. Implementations of the technology, however, are not limited to this case. In one alternative but non-limiting implementation, the side airbag units27R and27L of the navigator's seat3may also expand and deploy upon the occurrence of the side collision to the right side surface of the vehicle1. In this case, the occupant seated on the navigator's seat3may fall first toward the driver's seat2upon the occurrence of the side collision to the right side surface of the vehicle1. Accordingly, in the navigator's seat3, the vehicle controller10may perform the control to selectively cause the expansion and deployment of relevant one of the side airbag units27R and27L positioned on the side on which the driver's seat2is disposed, depending on which direction the navigator's seat3is oriented, frontward or rearward, in the front-rear direction of the vehicle1, prior to the expansion and deployment of another one of the side airbag units27R and27L positioned on opposite side to the driver's seat2. In another alternative but non-limiting implementation, the side airbag units24R and24L of the driver's seat2may also expand and deploy upon the occurrence of the side collision to the left side surface of the vehicle1. In this case, similarly, in the driver's seat2, the vehicle controller10may perform the control to selectively cause the expansion and deployment of relevant one of the side airbag units24R and24L positioned on the side on which the navigator's seat3is disposed, depending on which direction the driver's seat2is oriented, frontward or rearward, in the front-rear direction of the vehicle1, prior to the expansion and deployment of another one of the side airbag units24R and24L positioned on opposite side to the navigator's seat3.

Moreover, in this implementation, description is given on a case in which the driver's seat2and the navigator's seat3are frontward-oriented in the front-rear direction of the vehicle1, i.e., normally-oriented during the manual operation, or a case in which the driver's seat2and the navigator's seat3are rotated 180° in the horizontal plane from the frontward orientation to be rearward-oriented in the front-rear direction of the vehicle1. Implementations of the technology, however, are not limited to these cases. In one alternative but non-limiting implementation, the vehicle controller10may detect the frontward-oriented state of the driver's seat2and the navigator's seat3in the front-rear direction of the vehicle1, when the driver's seat2and the navigator's seat3are rotated 90° in the horizontal plane or less from the frontward orientation in the front-rear direction of the vehicle1, i.e., normal orientation during the manual operation. The vehicle controller10may detect the rearward-oriented state of the driver's seat2or the navigator's seat3in the front-rear direction of the vehicle1, when the driver's seat2or the navigator's seat3is rotated 90° in the horizontal plane or more from the frontward orientation in the front-rear direction of the vehicle1, i.e., the normal orientation during the manual operation. The expansion and deployment of the side airbag units24R,24L,27R, and27L may be performed on the basis of the control flow as described above. Other modifications may be made in variety of ways without departing from the scope of the technology.

According to the airbag unit of the implementations of the technology, the pair of side airbags are incorporated in the seat that is reversely rotatable in the front-rear direction of the vehicle. The sequence of the expansion and deployment of the pair of side airbags is appropriately controlled in accordance with the orientation of the seat in the front-rear direction of the vehicle. With this configuration, the side airbag expands and deploys first that is incorporated in the seat and located on the side of the vehicle on which the inner surface of the side wall of the vehicle is disposed. Hence, it is possible to provide appropriate protection for the occupant against the collision of the occupant with the inner surface of the side wall of the vehicle. The collision of the occupant with the inner surface of the side wall of the vehicle is considered to possibly cause severest damage to the occupant.

Moreover, the pair of side airbags may be incorporated inside the backrest of the seat. The pair of side airbags may be disposed in the bilateral symmetry with respect to the center line of the backrest of the seat in the width direction of the vehicle. With this configuration, the side airbag that expands and deploys toward the inner surface of the side wall of the vehicle is positioned at the same position as in a case in which the seat is frontward-oriented in the front-rear direction of the vehicle, even when the seat is rearward-oriented in the front-rear direction of the vehicle. Hence, it is possible to provide appropriate protection for the occupant.

Furthermore, the pair of side airbags may be expansive and deployable in the identical shapes. Hence, it is possible to provide appropriate protection for the occupant, with the side airbags that are expansive and deployable toward the inner surface of the side wall of the vehicle, even when the seat is rearward-oriented in the front-rear direction of the vehicle.

Moreover, the distance from the center of the seat cushion of the seat in the frontward-oriented state to the inner surface of the side wall of the vehicle may be equal to the distance from the center of the seat cushion of the seat in the rearward-oriented state to the inner surface of the side wall of the vehicle. This allows the position of the seat cushion in the case in which the seat is rearward-oriented in the front-rear direction of the vehicle to be the same as the position of the seat cushion in the case in which the seat is frontward-oriented in the front-rear direction of the vehicle. With this configuration, there is little change in the distance from the occupant seated on the seat to the curtain airbag, even when the seat is rearward-oriented in the front-rear direction of the vehicle. Hence, it is possible to provide appropriate protection for the head of the occupant.

Although some preferred implementations of the technology have been described in the foregoing by way of example with reference to the accompanying drawings, the technology is by no means limited to the implementations described above. It should be appreciated that modifications and alterations may be made by persons skilled in the art without departing from the scope as defined by the appended claims. The technology is intended to include such modifications and alterations in so far as they fall within the scope of the appended claims or the equivalents thereof.