Side airbag apparatus

An airbag main body is divided into a first inflation chamber, a second inflation chamber, and a third inflation chamber. The third inflation chamber is inflated beside the lumbar region of an occupant. The vertical partition has a communication hole that connects the first inflation chamber and the second inflation chamber to each other. The airbag main body has a gas passage, which extends in the up-down direction and surrounds at least the gas outlet of an inflator. The gas passage bridges the first inflation chamber and the third inflation chamber. The gas passage has an upper opening, which faces a part of the first inflation chamber that is inflated beside the shoulder region of the occupant. The gas passage also has a lower opening, which faces the third inflation chamber.

BACKGROUND OF THE INVENTION

The present invention relates to a side airbag apparatus that protects an occupant seated in a vehicle seat from an impact by deploying and inflating an airbag on a side of the occupant when an impact is applied to a vehicle.

A side airbag apparatus having an airbag and an inflator is widely known for protecting an occupant from an impact when the impact is applied to an automobile from a side to an automobile seat in which the occupant is seated, for example, due to a side collision. In the side airbag apparatus, an airbag is installed in a seat back of an automobile seat in a folded state together with an inflator. The outer shape of the airbag is formed by an airbag main body.

In the side airbag apparatus, when an impact is applied from the side on a side wall portion of an automobile body such as a side door, inflation gas is supplied from the inflator into the main body of an airbag, so that the airbag main body is deployed and inflated. The airbag is projected from the automobile seat with a part of the airbag remaining in the seat back. Thereafter, the airbag main body is deployed and inflated forward in a narrow space between the upper body of the occupant and the side wall portion. The airbag main body is located between the occupant and the side wall portion, which bulges inward, to restrain the occupant and reduces the impact from the side transmitted to the occupant via the side wall portion.

In the human body, the lumbar region and the shoulder region are generally known to have a better impact resistance than the thorax. Therefore, in the case of a side airbag apparatus that protects an occupant in a large area ranging from the lumbar region to the shoulder region, it is preferable that an airbag main body protect the thorax by softening the impact to thorax more than the impact to the lumbar region and the shoulder region.

In this connection, Japanese Laid-Open Patent Publication No. 2010-137615 discloses a side airbag apparatus that has an airbag main body divided into a plurality of inflation chambers. The inflation chambers are each inflated with an internal pressure appropriate for the impact resistance of the side of the occupant. In the side airbag apparatus, an airbag main body131is divided into a first inflation chamber134, a second inflation chamber135, and a pair of upper and lower third inflation chambers136,137as illustrated inFIG. 31. The second inflation chamber135is located in front of the first inflation chamber134with a vertical partition138in between. The third inflation chamber136is located above the first inflation chamber134and the second inflation chamber135with a lateral partition139in between. The third inflation chamber137is located below the first inflation chamber134with a lateral partition141in between.

The vertical partition138is formed by an inner tube encompassing the inflator133. The vertical partition138has an opening142, which connects the first inflation chamber134and the second inflation chamber135with each other. The upper lateral partition139has an opening143, which connects the first inflation chamber134and the third inflation chamber136with each other, and a check valve144, which prevents inflation gas in the third inflation chamber136from flowing back to the first inflation chamber134through the opening143. The lower lateral partition141has an opening145, which connects the first inflation chamber134and the third inflation chamber137with each other, and a check valve146, which prevents inflation gas in the third inflation chamber137from flowing back to the first inflation chamber134through the opening145.

According to the above described side airbag apparatus, part of the inflation gas discharged forward from the inflator133is supplied to the first inflation chamber134. The part of the inflation gas is supplied to the second inflation chamber135through the opening142, and other part of the inflation gas is supplied to the third inflation chamber136through the opening143and the check valve144. Part of the inflation gas discharged downward from the inflator133is promptly supplied to the third inflation chamber137through the opening145and the check valve146. Further, the check valves144,146prevent the internal pressures of the first inflation chamber134and the second inflation chamber135from being excessively increased at the restraint of the occupant. Also, the internal pressures of the third inflation chambers136,137, which have been raised to level appropriate for protecting the shoulder region and the lumbar region, are maintained.

In this manner, the third inflation chambers136,137are deployed and inflated with high internal pressures beside the shoulder region and the lumbar region, which have a high impact resistance, and the first inflation chamber134and the second inflation chamber135are deployed and inflated with low internal pressures beside the thorax, which has a low impact resistance. Thus, the airbag main body131is deployed and inflated with a pressure distribution appropriate for the impact resistance of the side of the occupant, so that the shoulder region, the lumbar region, and the thorax are effectively protected from an impact.

In the side airbag apparatus in the above document, part of the inflation gas discharged forward from the inflator133is promptly supplied to the second inflation chamber135through the opening142, so that the second inflation chamber135is deployed and inflated in the vicinity of the side of the thorax. The supply of inflation gas to the third inflation chamber136is delayed due to the supply of inflation gas to the second inflation chamber135. This possibly causes a delay in restraint and protection of the shoulder region of the occupant.

Accordingly, it is an objective of the present invention to provide a side airbag apparatus that is capable of promptly supplying inflation gas to the portions of an airbag that are inflated beside the shoulder region and the lumbar region of the occupant.

SUMMARY OF THE INVENTION

To achieve the foregoing objective and in accordance with one aspect of the present invention, a side airbag apparatus having an airbag main body is provided. The airbag main body is deployed and inflated beside an occupant seated in a vehicle seat by inflation gas that is supplied by an inflator in response to an impact applied from a side of the vehicle seat. The airbag main body includes a first inflation chamber, a second inflation chamber, which is located in front of and adjacent to the first inflation chamber, a vertical partition, which separates the first inflation chamber and the second inflation chamber from each other, a third inflation chamber, which is located below and adjacent to at least the second inflation chamber of the first and second inflation chamber, wherein the third inflation chamber is inflated beside the lumbar region of the occupant, and a lateral partition, which separates at least the second inflation chamber and the third inflation chamber from each other. The side airbag apparatus further includes a communication hole, a gas passage, an upper opening, and a lower opening. The communication hole is provided in the vertical partition to connect the first inflation chamber and the second inflation chamber to each other. The gas passage is provided in the airbag main body to surround at least a gas outlet of the inflator and extend substantially in an up-down direction. The gas passage bridges the first and third inflation chambers. The upper opening is provided at an upper end of the gas passage, wherein the upper opening faces a part of the first inflation chamber that is inflated beside the shoulder region of the occupant. The lower opening is provided at a lower end of the gas passage to face the third inflation chamber.

According to the above configuration, the inflation gas discharged from the gas outlet of the inflator is supplied to the gas passage and conducted upward or downward in response to an impact from the side of the vehicle seat. When reaching the upper end of the gas passage, the inflation gas flows to a section of the first inflation chamber that is inflated beside the shoulder region of the occupant. As a result, inflation gas is supplied to that section in the airbag main body, so that the section is promptly deployed and inflated between the occupant shoulder region and the vehicle side wall portion.

On the other hand, when reaching the lower end of the gas passage, the inflation gas flows to the third inflation chamber from the lower opening. The inflation gas is promptly supplied to the third inflation chamber to be promptly deployed and inflated between the lumbar region of the occupant and the vehicle side wall portion.

The inflation gas from the upper opening is supplied to the entire first inflation chamber so that the first inflation chamber is deployed and inflated. Further, part of the inflation gas in the first inflation chamber is supplied to the second inflation chamber though the communication hole in the vertical partition, so that the second inflation chamber is deployed and inflated.

As described above, the deployed and inflated airbag main body is located between the occupant and the vehicle side wall portion to restrain the occupant and reduce the impact from the side transmitted to the occupant via the side wall portion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

A side airbag apparatus according to a first embodiment will now be described with reference toFIGS. 1 to 20. The side airbag apparatus is installed in a vehicle, which is an automobile in the present embodiment.

In the following, the direction in which an automobile advances forward will be referred to as the front, and reverse direction will be referred to as the rear. The middle of the widthwise direction of the automobile is used as reference in the widthwise direction of the automobile. A side closer to the middle of the widthwise direction will be referred to as “inner side” of the automobile, while a side farther from the middle of the widthwise direction will be referred to “outer side” of the automobile.

It is provided that an average sized occupant (adult) is seated on an automobile seat in a predetermined posture (normal posture).

As shown inFIGS. 1 and 2, a vehicle seat, which is an automobile seat12in this embodiment, is arranged on the inner side of a side wall portion11of an automobile10. The side wall portion11refers to an automobile component that is located at a side of the automobile10, and mainly corresponds to a door and a pillar. For example, a part of the side wall portion11that corresponds to the front seat includes a front door and a center pillar (B-pillar). A part of the side wall portion11that corresponds to the rear seat includes a rear part of the side door (rear door), a C-pillar, a front part of the wheel well, and a rear quarter.

The automobile seat12includes a seat cushion13and a seat back14, which extends upward from the rear end of the seat cushion13. The automobile seat12is arranged in the automobile10such that the seat back14faces forward of the automobile10. The widthwise direction of the thus arranged automobile seat12matches with the direction of the vehicle width.

The seat back14includes a seat back main body15and a pair of side supports16, which is provided on both sides of the seat back main body15in the widthwise direction. The seat back main body15is tilted rearward, and supports the upper body of an occupant P from the rear. The side supports16protrude forward from the seat back main body15, and restrict the movement in the automobile widthwise direction of the upper body of the occupant P, who is seated on the seat cushion13and leaning against the seat back main body15.

The internal structure of the outer side portion of the seat back14including the outer side support portion16will now be described.

A seat frame, which forms a framework of the seat back14, is incorporated in the seat back14. As shown inFIG. 3, a part of the seat frame is located in the outer part of the seat back14. That part of the seat frame (hereinafter referred to as a side frame portion17) is formed by bending a metal plate. A seat pad18, which is made of an elastic material such as urethane foam, is provided on the front side of the seat frame, which includes the side frame portion17. Also, a hard back board19, which is formed, for example, of plastic, is arranged on the back of the seat frame. Although the seat pad18is coated with a cover, the cover is not illustrated inFIG. 3. The same applies toFIG. 17, which will be discussed below.

In the seat pad18, a storage portion21is provided in the vicinity of the outer side of the side frame portion17. The storage portion21accommodates an airbag module AM, which forms a main part of the side impact airbag apparatus.

A slit22is formed to extend from a corner of the storage portion21. The slit22extends diagonally forward and toward the exterior. A part between a front corner18cof the seat pad18and the slit22(a part surrounded by a broken line in which a long dash alternates with a pair of short dashes inFIG. 3) forms a breakable portion23, which is designed to be broken by an airbag40, which will be discussed below.

The airbag module AM includes as its main components an inflator assembly30and the airbag40.

As shown inFIGS. 3 to 5, the inflator assembly30includes a gas generator, which is an inflator31, and a retainer32, which surrounds the inflator31. In the first embodiment, a pyrotechnic type inflator is employed as the inflator31. The inflator31, which extends substantially in the up-down direction and has a substantially columnar shape, accommodates a gas generating agent (not shown), which generates inflation gas. The inflator31has a gas outlet31aat the lower end. A harness (not shown), which is wiring for sending activating signals to the inflator31, is connected to the upper end of the inflator31.

In place of the pyrotechnic type inflator using the gas generating agent, it is possible to use a hybrid type inflator, which discharge inflation gas by breaking a partition wall of a high-pressure gas cylinder filled with high-pressure gas with a low explosive.

The retainer32functions as a diffuser for controlling the direction of discharged inflation gas and also serves to fasten the inflator31, together with the airbag40, to the side frame portion17. Most of the retainer32is formed by bending a plate such as a metal plate into a cylindrical shape that extends substantially in the up-down direction. At least the lower end of the retainer32forms an open end32a. The retainer32has a window33substantially in front of the gas outlet31a. A considerable amount of inflation gas discharged from the inflator31is discharged substantially downward and forward of the retainer32through the open end32aand the window33.

Bolts34are fixed to the retainer32. The bolts34serve as securing members for attaching the retainer32to the side frame portion17.

The inflator31and the retainer32of the inflator assembly30may be integrated.

As shown inFIGS. 1 and 2, the outer shape of the airbag40is formed by an airbag main body41.

FIG. 4shows the airbag module AM in the state in which the airbag main body41is deployed in a planar form without being filled with inflation gas (hereinafter, referred to as an uninflated and deployed state).FIG. 5(a)shows, together with the occupant P, the airbag module AM in which the airbag main body41in the uninflated and deployed state ofFIG. 4is cut at the center portion of the automobile widthwise direction to show the internal structure of the airbag module AM.

As shown inFIGS. 4 and 5(a), the airbag main body41is formed by folding a single fabric piece (also referred to as a base fabric, or a fabric panel) along a folding line42set at the center portion to be overlapped in the widthwise direction of the automobile seat12(the automobile widthwise direction), and joining the overlapped portions into a bag shape. In the present embodiment, to distinguish the two overlapped portions of the airbag main body41, the part located on the inner side is referred to as a main body fabric portion43(seeFIG. 5(a)), and the part located on the outer side is referred to as a main body fabric portion44(seeFIG. 4).

In the first embodiment, the fabric piece is folded in half such that the folding line42is located at the rear end of the airbag main body41. However, the fabric piece may be folded in half such that the folding line42is located at another end such as the front end, the upper end, or the lower end. The airbag main body41may also be formed of two fabric pieces divided along the folding line42. In this case, the airbag main body41is formed by overlapping the two fabric pieces in the automobile widthwise direction, and joining the fabric pieces into a bag shape. Furthermore, the airbag main body41may be formed of three or more fabric pieces.

In the airbag main body41, the outer shapes of the main body fabric portions43,44are symmetric with respect to the folding line42(seeFIG. 6). The shape and size of the main body fabric portions43,44are set to be able to occupy the region on the side of most part of the upper body of the occupant P seated on the automobile seat12(the section from the lumbar region PP to the shoulder region PS) when the airbag main body41is deployed and inflated between the automobile seat12and the side wall portion11.

The main body fabric portions43,44are preferably formed of a material having high strength and flexibility to be easily folded. The material may be, for example, woven cloth formed of polyester threads or polyamide threads.

The main body fabric portions43,44are joined at peripheral joint portion45provided at the peripheries of the main body fabric portions43,44. In the first embodiment, most of the peripheral joint portion45is formed by sewing with sewing threads a part of the peripheries of the main body fabric portions43,44except the rear end (the part in the vicinity of the folding line42). This structure is common to outer joint portions72,84,85, inner joint portions73,93, joint portions76,77, a center joint portion111, and a peripheral joint portion112.

Three types of lines represent sewing portions inFIGS. 4 to 12 and 18. The first type of line includes thick lines with a certain length arranged intermittently and represents sewing threads as viewed from the side (refer to the peripheral joint portion45inFIG. 4). The second type of line includes thin lines with a certain length arranged intermittently and represents the sewing threads that are located, for example, behind the fabric piece and cannot be seen directly (refer to an inner joint portion93inFIG. 5(a)). The third type of line includes dots arranged at predetermined intervals and represents the cross-section of the sewing threads extending along the cross-section that passes through the sewn portions (refer to the peripheral joint portion45inFIG. 5(a)).

As shown inFIGS. 4 to 6, the space between the main body fabric portions43,44and surrounded by the peripheral joint portion45serves as an inflation portion46. When being deployed and inflated by inflation gas beside the upper body of the occupant P, the inflation portion46restrains the most part of the upper body and protects the upper body from the impact.

The peripheral joint portion45may be formed by method other than sewing using sewing thread as shown above, but may be formed by, for example, using an adhesive. This structure is common to outer joint portions72,84,85, inner joint portions73,93, joint portions76,77, a center joint portion111, and a peripheral joint portion112.

The main body fabric portions43,44have a slit47, which is located at the rear end and in a middle portion in the up-down direction in the folded state. The slit47intersects the folding line42. The main body fabric portions43,44also have a reinforcement portion48about the slit47. The reinforcement portion48reinforces the part about the slit47in the main body fabric portions43,44by sewing with sewing threads, thereby preventing the part from being torn.

A part of the main body fabric portions43,44above the slit47forms an inward folding portion49, which is folded inward of the remaining parts. The upper end of the inward folding portion49is joined to the remaining parts of the main body fabric portions43,44by the above described peripheral joint portion45. When the inward folding portion49is formed, the slit47is opened substantially in a circular shape to form an insertion port51for the inflator assembly30.

The inner side main body fabric portion43has bolt holes52(the number of which is two in the present embodiment), which are located in the vicinity of the folding line42and below the slit47. The bolts34of the retainer32are passed through the bolt holes52. A reinforcement portion53is formed about each bolt hole52by sewing with threads the part about the bolt hole52in the main body fabric portion43to reinforce the part surrounding the bolt hole52.

As shown inFIG. 5(a), the interior of the inflation portion46is divided into several chambers by a lateral partition64and a vertical partition81. The vertical partition81and the lateral partition64each have the same structure as a member generally referred to as a tether.

As shown inFIGS. 5(a)to6, the lateral partition64is formed by a single fabric piece that is formed of a material such as woven fabric having high strength and flexibility to be easily folded. Specifically, the lateral partition64is formed by folding a single fabric piece in half along a folding line65set at the center portion to be overlaid onto itself in the automobile widthwise direction, and placing the overlaid portion between lower parts of the main body fabric portions43,44. The lower parts of the main body fabric portions43,44are parts corresponding to the boundary between the lumbar region PP and the thorax PT of the occupant P.

The lateral partition64may also be formed of two fabric pieces divided along the folding line65.

To distinguish the two overlapped portions of the lateral partition64, the part located on the inner side is referred to as a structural fabric portion66, and the part located on the outer side is referred to a structural fabric portion69(seeFIG. 16).

The inner structural fabric portion66includes a main body forming fabric portion67, which extends from the rear end to the front end of the main body fabric portion43, and an extension68, which extends forward and diagonally downward from the rear end of the main body forming fabric portion67. The outer structural fabric portion69includes a main body forming fabric portion70, which extends from the rear end to the front end of the main body fabric portion44, and an extension71, which extends forward and diagonally downward from the rear end of the main body forming fabric portion70.

The lateral partition64, which is folded in half as described above, is located between the main body fabric portions43,44with the folding line65matched with the folding line42(FIGS. 16 and 20). The inner side main body forming fabric portion67has an outer joint portion72formed along the upper periphery and is joined to the inner side main body fabric portion43by the outer joint portion72. Likewise, the outer side main body forming fabric portion70has an outer joint portion72formed along the upper periphery and is joined to the outer side main body fabric portion44by the outer joint portion72. Further, the main body forming fabric portions67,70are joined to each other by an inner joint portion73located at the lower peripheries.

Further, the front ends of the main body forming fabric portions67,70are joined to (sewn together with) the front ends of the main body fabric portions43,44by the peripheral joint portion45.

A part of the inflation portion46below the lateral partition64forms a third inflation chamber63, which is deployed and inflated beside the lumbar region PP of the occupant P seated in the automobile seat12. Since the lateral partition64is located between the main body fabric portions43,44and at a position below the center in the up-down direction, the third inflation chamber63has a volume that is less than the total volume of the chambers above the lateral partition64.

When the inflation portion46is deployed and inflated, the lateral partition64is tensed in the automobile widthwise direction to limit the thickness of the inflation portion46in the same direction (seeFIG. 20).

InFIGS. 13 to 16, which illustrate the internal structure of the airbag40, the each component is depicted thinner than in reality. The inner joint portions93are represented as zigzag lines inFIG. 13. As shown inFIGS. 5, 13, and 14, when the airbag main body41is in the uninflated and deployed state, the vertical partition81is folded in half along a folding line82, which extends substantially in the up-down direction intersecting the lateral partition64, between the main body fabric portions43,44. The folded vertical partition81is arranged between the main body fabric portions43,44with the folding line82located upstream of the peripheries (at a position closer to the inflator assembly30).

As shown inFIGS. 4 and 10, the upper end of the folded vertical partition81is joined to (sewn together with) the upper ends of the main body fabric portions43,44by the peripheral joint portion45.

Also, the folded vertical partition81is arranged between the structural fabric portions66,69at the lower end and overlaid onto the rear parts of the main body forming fabric portions67,70. The lower end of the folded vertical partition81is joined to (sewn together with) the main body forming fabric portions67,70of the lateral partition64by the inner joint portion73.

As shown inFIG. 6, the dimension of the vertical partition81in the direction of the folding line82(hereinafter, referred to as a vertical direction) is longer than the dimension in the direction perpendicular to the folding line82(hereinafter, referred to as a lateral direction). As shown inFIG. 10, parts of the vertical partition81that are not overlaid onto the main body forming fabric portions67,70of the lateral partition64are joined to the main body fabric portions43,44by outer joint portions84provided along the periphery thereof. Parts of the vertical partition81that are overlaid onto the main body forming fabric portions67,70are joined only to the main body forming fabric portions67,70by outer joint portions85, which are provided along the peripheries and located below the outer joint portions84(seeFIG. 15).

The vertical partition81extends between the main body fabric portions43,44by the above described joining operation. When the airbag main body41is in the uninflated and deployed state, the vertical partition81is folded in half (seeFIGS. 5(a), and13to15). When a first inflation chamber61is inflated, the vertical partition81is tensed in the lateral direction (the vehicle widthwise direction, refer toFIG. 18) to limit the thickness of the first inflation chamber61.

As shown inFIG. 5(a), an inflation chamber that is above the lateral partition64and rearward of the vertical partition81forms the first inflation chamber61. An inflation chamber forward of the vertical partition81forms a second inflation chamber62. When the first and second inflation chambers61,62are deployed and inflated, the vertical partition81is located in the vicinity of the boundary between the rear half and the front half of the upper body of the occupant P. The first inflation chamber61is deployed and inflated beside the shoulder region PS and the rear half of the thorax PT in the upper body of the occupant P. The second inflation chamber62is deployed and inflated beside the front half of the thorax PT.

As illustrated inFIGS. 10 and 18, the vertical partition81has two fabric pieces86,87, which are arranged in the vertical direction (the up-down direction). The fabric pieces86,87are formed of a material such as woven fabric having high strength and flexibility to be easily folded.

As shown inFIG. 18, the upper and lower fabric pieces86,87are overlaid onto each other in a band-like shape with the edges88e,89ethereof being aligned with each other. The upper and lower fabric pieces86,87are joined to each other at the inner joint portions93, which extend in the lateral direction (the automobile widthwise direction) at the boundary between the band-like overlapping portions91and the remaining parts (hereinafter, referred to as non-overlapping portions92).

At least one of the upper fabric piece86and the lower fabric piece87of the vertical partition81may be divided into two along the folding line82.

As shown inFIGS. 5(a)and7, a gas passage100is formed in the airbag main body41. The gas passage100extends substantially in the up-down direction and surrounds at least the gas outlet31aof the inflator31. Also, the gas passage100bridges the first inflation chamber61and the third inflation chamber63.

The gas passage100is formed by an inner tube101, which extends substantially in the up-down direction in a rear portion of the airbag main body41and intersects the lateral partition64. The inner tube101is located at the rear end of the interior of the airbag main body41in a state wrapping the lower half of the inflator31, which includes the gas outlet31a, and the lower half of the retainer32, which includes the window33. The inner tube101regulates the flow of inflation gas discharged by the inflator31to direct the flow upward or downward.

Like the airbag main body41, the inner tube101is formed by a single fabric piece that is formed of a material such as woven fabric having high strength and flexibility to be easily folded.

The inner tube101is formed by folding the single fabric piece along a folding line102, which is set at the center portion and extends in the up-down direction, to be overlaid onto itself in the automobile widthwise direction, and joining the fabric piece such that the overlaid portions form a tubular shape.

The inner tube101may also be formed of two fabric pieces divided along the folding line.

To distinguish the two overlapped parts of the inner tube101, the part located on the inner side is referred to as a structural fabric portion103, and the part located on the outer side is referred to a as structural fabric portion106. The inner side structural fabric portion103includes a main body forming fabric portion104, which has a substantially rectangular shape extending substantially in the up-down direction, and an extension105, which extends forward and downward from the lower end of the main body forming fabric portion104. The upper end of the main body forming fabric portion104is located at the upper end of the first inflation chamber61. The main body forming fabric portion104has a bolt hole109at a position that corresponds to the bolt hole52of the main body fabric portion43. The extension105substantially has the same shape as the inner side extension68of the lateral partition64, which is described above.

The outer side structural fabric portion106includes a main body forming fabric portion107, which has a substantially rectangular shape extending substantially in the up-down direction, and an extension108, which extends forward and downward from the lower end of the main body forming fabric portion107. The upper end of the main body forming fabric portion107is located at the upper end of the first inflation chamber61. The extension108substantially has the same shape as the outer side extension71of the lateral partition64, which is described above.

A slit113is formed in the main body forming fabric portions104,107at a position corresponding to the slit47of the airbag main body41. The slit113extends across the folding line102.

The bolt hole109and the slit113may be formed after the step for attaching the inner tube101to the airbag main body41, more specifically, after the center joint portion111, which will be discussed below, is formed.

The inner tube101, which is folded in half as described above, is located between the structural fabric portions66,69with the folding line102matched with the folding lines42,65. The inner tube101is joined to the airbag main body41and the lateral partition64by a center joint portion111formed along the folding line102(seeFIG. 8). The folded parts of the inner tube101are joined to each other by a peripheral joint portion112, which is provided along the facing edges of the main body forming fabric portions104,107.

The peripheral joint portion112extends linearly substantially in the up-down direction. The upper end of the peripheral joint portion112is separated downward from the upper end of the inner tube101by a predetermined distance. That is, the upper ends of the main body forming fabric portion104,107are not joined to each other by the peripheral joint portion112. The part forms an upper opening114, which opens toward a part of the first inflation chamber61that is inflated beside the shoulder region PS of the occupant P. The lower end of the peripheral joint portion112is located at the lower ends of the main body forming fabric portions104,107.

Further, the upper ends of the folded main body forming fabric portions104,107are joined to (sewn together with) the rear upper ends of the main body fabric portions43,44by the above described peripheral joint portion45.

Most of the inflator assembly30is arranged to extend substantially in the up-down direction when accommodated in the rear end portion of the airbag main body41. The upper portion of the inflator assembly30extends through insertion port51to be exposed to the outside of the airbag main body41. The bolt34of the retainer32is passed through the bolt holes109,52. The insertion of the bolts34engages the inflator assembly30to the inner tube101and the airbag main body41in a state where the position is determined with respect the airbag main body41. In this state, the gas outlet31ais located at a position that is rearward of the first inflation chamber61and in the vicinity of the third inflation chamber63.

As shown inFIGS. 5(a), 5(b), and6, the lateral partition64and the inner tube101have a lower opening74and a check valve75, and the vertical partition81has a communication hole94and a pressure regulator valve97.

As shown inFIGS. 5(a), 5(b), and6, the inner joint portion73of the lateral partition64is disjoined in rear parts of the main body forming fabric portions67,70. In other words, the inner joint portion73, which joins the main body forming fabric portions67,70to each other, is absent in an area across the folding line65. The part that is disjoined, or the part where the inner joint portion73is not provided, and the corresponding lower end of the inner tube101form the lower opening74, which opens toward the third inflation chamber63.

The check valve75is configured to restrict the flow of inflation gas at the lower opening74. That is, the check valve75allows inflation gas to flow from the first inflation chamber61to the third inflation chamber63, but restricts the outflow in the opposite direction (backflow).

The front peripheral portions of the folded extensions68,71and the front peripheral portions of the folded extensions105,108are joined to each other by a joint portion76provided along the front peripheral portions. The upper end of the joint portion76is connected to the rear end of the joint portion73. The rear parts of the folded extensions68,71and the rear parts of the folded extensions105,108are joined to each other by a joint portion77provided along the rear peripheral portions. The joint portions76,77are inclined to be lowered toward the front ends.

Further, parts of the folded extensions68,71that are rearward of the joint portion77and parts of the folded extension105,108that are rearward of the joint portion77are joined to (sewn together with) each other by the peripheral joint portion45, together with the rear lower ends of the main body fabric portions43,44. Parts of the inner side extensions68,105that are surrounded by the lower opening74and the joint portions76,77form a valve body78on the inner side of the check valve75. Also, parts of the outer side extensions71,108that are surrounded by the lower opening74and the joint portions76,77form a valve body79on the outer side of the check valve75.

The check valve75allows flow of inflation gas when one of the valve bodies78,79is separated from the other. This state of the check valve75is referred to as a valve opening state. The check valve75restricts flow of inflation gas when the valve bodies78,79contact each other in at least parts thereof. This state of the check valve75is referred to as a valve closing state.

As shown inFIGS. 5(a), 5(b), and18, the communication hole94and the pressure regulator valve97are located substantially at a center in the vertical direction and the lateral direction. Specifically, the inner joint portion93in the vertical partition81is disjoined at a part across the folding line82. In other words, the inner joint portion93, which joins the upper and lower fabric pieces86,87to each other, is absent at a part that extends across the folding line82in the boundary between the overlapping portions91and the non-overlapping portions92. A disjoined part where the inner joint portion93is not provided forms the communication hole94, which is a slit that extends in the lateral direction (the automobile widthwise direction) and connects the first inflation chamber61and the second inflation chamber62to each other.

The communication hole94is formed to have a greater flow resistance of inflation gas than that of the upper opening114of the gas passage100. More specifically, the communication hole94is formed to have a smaller flow passage area when opened than that of the upper opening114when opened.

The pressure regulator valve97adjusts the flow of inflation gas at the communication hole94, thereby regulating the internal pressures in the first inflation chamber61and the second inflation chamber62. More specifically, the pressure regulator valve97is closed before the first inflation chamber61is inflated and restrains the occupant P, thereby restricting the outflow of inflation from the first inflation chamber61to the second inflation chamber62through the communication hole94. After the first inflation chamber61restrains the occupant P, the pressure regulator valve97opens in response to a change in the tensed state of the vertical partition81due to the applied external force generated by the restraint, thereby cancelling the restraint.

A part of the overlapping portion91that is between the communication hole94and the edge88eforms a valve body95of the pressure regulator valve97, and a part of the overlapping portion91that is between the communication hole94and the edge89eforms a valve body96of the pressure regulator valve97. When the valve bodies95,96contact each other at least partially, for example, at the distal ends95t,96t, the flow of the inflation gas through between the valve bodies95,96is restricted (seeFIGS. 19(a), 19(b)). This state of the pressure regulator valve97is referred to as a valve closing state. Also, when the communication hole94is opened, and the entire valve body95is separated from the entire valve body96, inflation gas is allowed to flow through between the valve bodies95,96(seeFIG. 19(c)). This state of the pressure regulator valve97is referred to as a valve opening state.

At the boundary between the overlapping portions91and the non-overlapping portions92, the overlapping portions91are folded upward or downward (upward in the first embodiment) to be overlaid onto one of the non-overlapping portions92. Further, the folded band-like overlapping portions91are joined to (sewn together with) the main body fabric portions43,44of the airbag main body41and the non-overlapping portions92at the ends in the direction along the inner joint portion93(the lateral direction, the automobile widthwise direction) by the outer joint portions84(seeFIGS. 5(a)and18).

The pressure regulator valve97acts as a resistance against flow of inflation gas when it flows through the communication hole94of the vertical partition81. Thus, the flow resistance that acts against the inflation gas when it passes through the communication hole94is greater than that in a case where the pressure regulator valve97is not provided. Therefore, the flow resistance that acts on the inflation gas when it passes through the communication hole94is further greater than the flow resistance that acts on inflation gas when it passes through the upper opening114of the gas passage100.

The airbag40of the side airbag apparatus according to the first embodiment is constructed as described above.

A method for manufacturing the airbag40will now be described with reference toFIGS. 7 to 12. Particularly, a method for installing the lateral partition64and the vertical partition81to extend between the main body fabric portions43,44will be described. In the manufacture, the following first to fifth joining steps are sequentially performed.

As shown inFIG. 7, the airbag main body41and the lateral partition64are spread in the first joining step. The slit47, the reinforcement portions48,53, and the bolt holes52are formed in the airbag main body41in advance. With the folding line65matched with the folding line42, the lateral partition64is overlaid onto a lower part of the airbag main body41. The inner side main body forming fabric portion67is sewn at its upper peripheral portion to the main body fabric portion43, and the outer side main body forming fabric portion70is sewn at its upper peripheral portion to the main body fabric portion44. The outer joint portion72is thus formed.

As shown inFIGS. 7 and 8, the inner tube101as well as the airbag main body41, to which the lateral partition64is joined, is spread in the second joining step. With the folding line102matched with the folding lines42,65, the inner tube101is overlaid onto the airbag main body41and the lateral partition64.

The lower part of the inner tube101is sewn to the airbag main body41and the lateral partition64along a part of the folding line102, so that the center joint portion111is formed. The thus formed center joint portion111temporarily attaches the inner tube101to the airbag main body41and the lateral partition64, while determining the relative positions.

In the inner side structural fabric portion103, the bolt holes109are formed at positions that correspond to the bolt holes52of the main body fabric portion43. The slit113is formed in the inner side structural fabric portions103,106at a position that corresponds to the slit47of the airbag main body41.

As shown inFIG. 9, the inner tube101is folded forward in half along the folding line102, and the structural fabric portion103and the structural fabric portion106are overlaid onto each other. The main body forming fabric portions104,107are sewn to each other at the facing peripheral portions in the up-down direction, so that the peripheral joint portion112is formed. The peripheral joint portion112joins the main body forming fabric portions104,107to each other to form a flat tube.

As shown inFIG. 10, the rear part of the airbag main body41and the rear part of the lateral partition64are folded in half along the folding lines42,65in the third joining step. At this time, the flat and normal main body forming fabric portion104,107are accommodated in the folded portion. In this state, the airbag main body41except for the rear part and the lateral partition64except for the rear part are spread.

The spread vertical partition81is overlaid onto the partly spread airbag main body41and the partly spread lateral partition64. The vertical partition81is formed by joining the upper and lower fabric pieces86,87to each other by the inner joint portion93to form the communication hole94and the pressure regulator valve97.

Parts of the peripheries of the vertical partition81that are not overlaid on the structural fabric portions66,69of the lateral partition64are sewn to the main body fabric portions43,44, so that a pair of the outer joint portions84is formed. Also, parts of the peripheries of the vertical partition81that are overlaid on the structural fabric portions66,69are sewn only to the main body forming fabric portions67,70, so that a pair of the outer joint portions85is formed below the outer joint portions84. The outer joint portions85join the vertical partition81to the lateral partition64.

The outer joint portions84may be formed either before or after the outer joint portions85are formed.

As show inFIG. 11, in the fourth joining step, the partly spread portions in the third joining step (the airbag main body41, the lateral partition64, and the vertical partition81) are folded in half along the folding line82of the vertical partition81(seeFIG. 10). In this state, the lower peripheries of the main body forming fabric portions67,70are sewn to each other to form the inner joint portion73and the lower opening74. The front peripheries of the extensions68,71,105,108are sewn together to form the joint portion76, and the rear edges are sewn together to form the joint portion77. As the joint portions76,77are formed, the check valve75, which has the valve bodies78,79, is formed at the intersection of the lateral partition64and the inner tube101. When the check valve75is formed, the inner tube101is simultaneously joined to the lateral partition64.

At the fourth joining step, as shown inFIG. 11, parts of the main body fabric portions43,44of the airbag main body41that are below the outer joint portion72are folded upward and outward so that the lateral partition64is exposed. InFIG. 11, the outer side main body fabric portion44is shown with a part cut away.

In the fifth joining step, parts of the main body fabric portions43,44that are above the slit47are folded into the remaining parts, so that the inward folding portion49is formed as shown inFIGS. 11 and 12. In this state, the peripheries of the main body fabric portions43,44are sewn together to from the peripheral joint portion45. The peripheral joint portion45joins the main body fabric portions43,44to each other and joins (sews together) the upper end of the inward folding portion49to the remaining parts of the main body fabric portions43,44. In addition, the front ends of the main body forming fabric portions67,70of the lateral partition64are joined to (sewn together with) the front ends of the main body fabric portions43,44, and the parts of the extensions68,71,105,108that are rearward of the joint portion77are joined to (sewn together with) the rear lower ends of the main body fabric portions43,44. Further, the upper ends of the folded vertical partition81and the inner tube101are joined to (sewn together with) the upper ends of the main body fabric portions43,44.

In this manner, the airbag40is formed, which includes the lateral partition64and the vertical partition81, which extend between the main body fabric portions43,44, and the inner tube101, which intersects with the lateral partition64.

Since the airbag40in the uninflated and deployed state (seeFIGS. 4 to 5B) is folded as shown inFIG. 3, the airbag module AM, which includes the inflator assembly30and the airbag40as main components, is made into a compact stage form. The airbag module AM is folded in this manner in order that it is suitable for being accommodated in the storage portion21having a limited size in the seat back14.

The bolts34extend from the retainer32and are passed through the inner tube101and the main body fabric portion43of the airbag main body41and are passed through the side frame portion17. A nut35is threaded onto each bolt34. The fastening secures the inflator assembly30to the side frame portion17together with the airbag40.

The inflator assembly30may be attached to the side frame portion17using members other than the bolt34and the nut35. The inflator31may be directly attached to the side frame portion17without using the retainer32.

As shown inFIG. 1, the side airbag apparatus includes an impact sensor121and a controller122in addition to the above-described airbag module AM. The impact sensor121is formed by an acceleration sensor and is provided on the side wall portion11of the automobile10(seeFIG. 2) to detect an impact applied from the side of the side wall portion11. The controller122controls the operation of the inflator31based on a detection signal from the impact sensor121.

Furthermore, the automobile10is equipped with a seat belt apparatus for restraining the occupant P seated on the automobile seat12. However, illustration of the seat belt apparatus is omitted inFIG. 1.

The side airbag apparatus of the first embodiment is constructed as described above. The typical operation mode will now be described as operation of the side airbag apparatus.

FIGS. 19(a) to 19(c)schematically show the forms of the pressure regulator valve97and the vertical partition81being changed over time after the inflation gas starts to be supplied, and detailed parts are omitted or simplified.

In the side airbag apparatus, when no impact is applied to the side wall portion11of the automobile10, for example, due to a side collision, the controller122sends no activation signal to the inflator31, so that the inflator31does not discharge inflation gas. The airbag40thus remains stored in the storage portion21in the storage form (seeFIG. 3).

In contrast, when the impact sensor121detects that an impact of a magnitude greater than or equal to a predetermined value has been applied to the side wall portion11due to a side collision or the like while the automobile10is running, the controller122, based on the detection signal, sends an activation signal to the inflator31to activate the inflator31(seeFIGS. 1 and 2). In response to the activation signal, the inflator31discharges inflation gas through the gas outlet31a. Some of the inflation gas flows forward via the window33of the retainer32, which is shown inFIG. 5, and then strikes the inner tube101. This changes the direction of the flow to upward or downward direction. The inflation gas inflates the inner tube101so that, in the rear section of the airbag main body41, the part about the inner tube101is deployed and inflated in the up-down direction.

When reaching the upper end of the gas passage100, the inflation gas flows from the upper opening114to a section of the first inflation chamber61that is inflated beside the shoulder region PS of the occupant P. The inflation gas is thus promptly supplied to the section of the airbag main body41. The inflation gas thus starts inflating the section and sections thereabout in the first inflation chamber61.

The inflation gas discharged from the lower open end32aof the retainer32and the inflation gas the direction of which has been changed to the downward direction by the inner tube101flow to the lower end of the gas passage100. When reaching the lower end, the inflation gas flows to the third inflation chamber63from the lower opening74via the check valve75. During the period in which inflation gas is passing through the check valve75, the valve bodies78,79receives a force that acts to change the shape of the valve bodies78,79into a tubular shape. The inflation gas is therefore promptly supplied to the third inflation chamber63through the lower opening74and through between the valve bodies78,79.

The volume of the third inflation chamber63is less than the total volume of the first inflation chamber61and the second inflation chamber62. Thus, if the same amount of inflation gas passes through both of the upper opening114and the lower opening74of the gas passage100, the third inflation chamber63would be filled with inflation gas earlier than the first inflation chamber61and the second inflation chamber62.

The lateral partition64is pulled in the lateral direction (the automobile widthwise direction) by the first inflation chamber61and the third inflation chamber63in the process of inflation. The continuous supply of the inflation gas from the inflator31increases the internal pressure of the third inflation chamber63.

As the first inflation chamber61starts being inflated, the folded vertical partition81is pulled in the lateral direction (the vehicle widthwise direction) by the first inflation chamber61, which is being inflated.

As shown inFIG. 19(a), an internal pressure PI is applied to the valve bodies95,96of the pressure regulator valve97in the overlapping direction (the thickness direction). The valve bodies95,96are brought into close contact in the entire surfaces with each other by the internal pressure PI, and are in a self-sealing state, which restricts the flow of the inflation gas through between the valve bodies95,96. Furthermore, the overlapping portions91, which has been folded and overlaid onto the non-overlapping portion92of the vertical partition81, is pressed against the non-overlapping portion92by the internal pressure (seeFIG. 18). This allows the valve bodies95,96to be further easily closed.

As shown inFIG. 6, the vertical partition81is formed to be longer in the vertical direction (the up-down direction) than in the lateral direction (the automobile widthwise direction). Thus, in the vertical partition81, stronger tension tends to be applied in the lateral direction (the automobile widthwise direction) than in the longitudinal direction (the up-down direction). In the first embodiment, since the communication hole94extends in the lateral direction (the automobile widthwise direction), in which the strong tension tends to be applied, the communication hole94is easily closed.

Further, when the first inflation chamber61is deployed and inflated, strong tension in the lateral direction (the automobile widthwise direction) is applied not only to the non-overlapping portion92of the vertical partition81, but also to the overlapping portions91. This is because the ends of the overlapping portions91are joined to the main body fabric portions43,44.

When the valve bodies95,96at least partially contact each other, the pressure regulator valve97is closed. The inflation gas in the first inflation chamber61is restricted from flowing into the second inflation chamber62through between the valve bodies95,96and the communication hole94. The restriction of gas flow causes the inflation gas to be accumulated in the first inflation chamber61, so that the internal pressure of the first inflation chamber61is mainly increased.

In the first embodiment, since a part of the inflation portion46that is above the lateral partition64is divided into two sections, one of which is the first inflation chamber61. The volume of the first inflation chamber61is thus smaller than it would be if the part were not divided by the vertical partition81. Thus, the internal pressure of the first inflation chamber61starts to increase earlier and to a higher level than it would be if the part were not divided by the vertical partition81.

At this time, the inflation portion46is yet to contact the occupant P.

When the internal pressures increase and the first inflation chamber61and the third inflation chamber63are inflated, while being unfolded (deployed) in the reverse order of the folding order, the seat pad18of the seat back14is pushed by the first inflation chamber61and the third inflation chamber63and breaks at the breakable portion23(seeFIG. 3). As shown inFIG. 17, the first inflation chamber61and the third inflation chamber63are projected forward from the seat back14through the broken part while parts thereof are remaining in the storage portion21.

Since inflation gas is promptly supplied to a section of the first inflation chamber61that is inflated beside the shoulder region PS of the occupant P as described above, the section is promptly deployed and inflated between the shoulder region PS and the side wall portion11, and the internal pressure thereof is increased at an early stage.

The flow resistance against inflation gas when it passes through the communication hole94of the vertical partition81is greater than that against inflation gas when it passes through the upper opening114of the gas passage100. Thus, the inflation gas less easily passes through the communication hole94than through the upper opening114. That is, the inflation gas less easily flows from the first inflation chamber61to the second inflation chamber62than from the upper opening114of the gas passage100to the first inflation chamber61. Therefore, the section of the first inflation chamber61that is inflated beside the shoulder region PS is deployed and inflated preferentially compared to other sections of the first inflation chamber61and the second inflation chamber62.

Since the inflation gas promptly supplied to the third inflation chamber63, the third inflation chamber63is promptly deployed and inflated between the lumbar region PP of the occupant P and the side wall portion11, and the internal pressure of the third inflation chamber63is increased at an early stage.

In the first embodiment, the inflator31is arranged such that the gas outlet31ais located at the lower end, and the gas outlet31ais located at a position closer to the upper opening114than to the lower opening74of the gas passage100. Therefore, inflation gas is preferentially supplied to the third inflation chamber63from the lower opening74so that the internal pressure of the third inflation chamber63is increased promptly.

The inflation gas is supplied to the entire first inflation chamber61so that the first inflation chamber61is deployed and inflated at sections other than the section beside the shoulder region PS of the occupant P, for example, at a section corresponding to the rear half of the thorax PT. At this time, the second inflation chamber62is yet to be inflated or only slightly inflated with a low internal pressure.

As shown inFIG. 18, the vertical partition81is tensed when pulled in the lateral direction (the automobile widthwise direction). The tensed vertical partition81limits the thickness of the inflated first inflation chamber61in the same direction. Also, as shown inFIG. 20, the lateral partition64is tensed when pulled in the lateral direction (the automobile widthwise direction). The tensed lateral partition64limits the thickness of the inflated first and third inflation chambers61,63in the same direction.

When the side wall portion11bulges further inward, the shoulder region PS of the occupant P starts being pushed toward the center of the automobile10by the first inflation chamber61. As the first inflation chamber61pushes the shoulder region PS and the rear half of the thorax PT and as the third inflation chamber63pushes the lumbar region PP, the occupant P is moved inward and restrained. By this movement, the distance between the occupant P and the side wall portion11is increased, and the space for deploying and inflating the second inflation chamber62is ensured.

At the pushing action, only the first inflation chamber61in the part of the inflation portion46above the lateral partition64is deployed and inflated. The occupant P thus mostly contacts the first inflation chamber61while receiving pressure of the inflation portion46.

The inflation gas continues being supplied to the first inflation chamber61with the valve bodies95,96closely contacting each other in the entire surfaces and closed. At this time, external force applied from the side wall portion11causes the pressure regulator valve97to start opening.

That is, the inflation portion46starts being deformed by external force that accompanies the restraint of the occupant P in the middle of the supplying period of inflation gas to the first inflation chamber61. Accordingly, the tension strongly applied to the vertical partition81in the lateral direction (the automobile widthwise direction) is decreased, and the tension applied in the vertical direction (the up-down direction) is increased.

Also, the internal pressure of the first inflation chamber61is further increased in accordance with the deformation of the inflation portion46, and the vertical partition81is pushed toward the second inflation chamber62(seeFIG. 19(b)). Thus, the tension applied to the vertical partition81is changed. As the tension is changed, the difference between the tension acting in the vertical direction and the tension acting in the lateral direction is reduced. Then, the communication hole94located on the vertical partition81is permitted to be deformed, and the valve bodies95,96on the vertical partition81are permitted to operate.

The overlapping portions91are overlapped with the non-overlapping portions92, and are joined to the main body fabric portions43,44by the outer joint portions84at the ends in the lateral direction (the automobile widthwise direction). Therefore, the force that acts to maintain the overlapped state is strong at the parts of the overlapping portions91close to the outer joint portions84. However, the force is reduced as the distance from the outer joint portions84is increased, and the force is minimized at the center in the lateral direction (the automobile widthwise direction), that is, on the valve bodies95,96. Thus, the overlapping portions91, which are pulled in the vertical direction (up-down direction), are deformed in the vertical direction at the valve bodies95,96and in the vicinity thereof.

When the communication hole94is opened in the vertical direction (up-down direction) by a certain amount, only the valve bodies95,96of the overlapping portions91, which have received high internal pressure PI of the first inflation chamber61, are pushed out (reversed) into the second inflation chamber62via the communication hole94. When the width W1of the communication hole94in the up-down direction is narrow, the distal ends95t,96tcontact each other to close the pressure regulator valve97.

Then, as the width W1of the communication hole94increases, the distal ends95t,96tseparate from each other to open the pressure regulator valve97as shown inFIG. 19(c). At this time, the restriction of flow is cancelled so that the inflation gas in the first inflation chamber61is permitted to flow to the second inflation chamber62via the communication hole94and between the valve bodies95,96.

As the inflation gas flows out, the internal pressure of the first inflation chamber61switches from increasing to decreasing. However, since the side wall portion11continues bulging inward, the inflation portion46is pushed against the occupant P at the first inflation chamber61.

Also, the second inflation chamber62starts being inflated by inflowing inflation gas, and the internal pressure of the second inflation chamber62starts increasing. This causes the second inflation chamber62to be unfolded (deployed) in the reverse order of that when it is folded.

At this time, the second inflation chamber62is deployed and inflated beside the front half of the thorax PT, which has a lower impact resistance than the shoulder region PS, with an internal pressure lower than that of the first inflation chamber61. In this state, the first inflation chamber61and the third inflation chamber63have increased the space between the side wall portion11and the occupant P, and the space for deploying and inflating the second inflation chamber62is ensured. Therefore, compared to a case in which such an increase in the space does not take place, the second inflation chamber62can be easily deployed and inflated.

Slightly after the start of the increase in the internal pressure of the second inflation chamber62, the side wall portion11, which is bulging inward, starts pressing the second inflation chamber62against the upper body of the occupant P, in addition to the first inflation chamber61. That is, the upper body starts being restrained by the second inflation chamber62in addition to the first inflation chamber61.

The airbag40, in which the first inflation chamber61, the second inflation chamber62, and the third inflation chamber63are each deployed and inflated as described above, is located between the upper body of the occupant P and the inwardly bulging side wall portion11. The airbag40pushes the upper body inward of the automobile and restrains the upper body. The side impact transmitted to the upper body through the side wall portion11is reduced by the inflation portion46and the upper body is protected.

The impact resistance of the upper body of the occupant P is generally higher in the rear half of the upper body than in the front half. This is because the rear half includes the spine and the ribs are connected to the spine at the rear ends, while the front ends of the ribs are not connected to any structure having a strength as the spine. Therefore, as the inflation chambers above the lateral partition64are deployed and inflated, the internal pressure of the inflation portion46that acts on the side of the upper body of the occupant P is preferably lower in the front half than in the rear half.

In this respect, a part of the inflation portion46that is above the lateral partition64is inflated such that the vertical partition81is located in the vicinity of the boundary between the front half and the rear half of the upper body with respect to the front-rear direction in the first embodiment. When the inflation portion46is deployed and inflated, the first inflation chamber61is located in the vicinity of the side of the rear half, and the second inflation chamber62is located in the vicinity of the side of the front half. Therefore, at an initial stage of the restraint of the occupant P by the airbag40, the rear half, which has a higher impact resistance than the front half, is pushed by the first inflation chamber61, the internal pressure of which is increased at an early stage. Also, at the initial stage of the restraint, the front half, which has a relatively low impact resistance, is pressed by the second inflation chamber62, the internal pressure of which is not as increased as the pressure of the first inflation chamber61.

As shown inFIG. 5, when the discharge of inflation gas from the inflator31stops and the inflation gas in the third inflation chamber63acts to flow to the first inflation chamber61, the valve bodies78,79of the check valve75are pushed by the high pressure in the third inflation chamber63and contact each other. When the check valve75is closed, the inflation gas in the third inflation chamber63is restricted from flowing back to the first inflation chamber61through between the valve bodies78,79and the lower opening74.

Therefore, the internal pressure of the third inflation chamber63, which has been increased to a level adequate for protecting the lumbar region PP of the occupant P, is maintained at the high level.

Thereafter, while allowing inflation gas to flow from the first inflation chamber61to the third inflation chamber63, the check valve75restricts the inflation gas in the third inflation chamber63from flowing back to the first inflation chamber61. Therefore, if, for example, the internal pressure of the third inflation chamber63is increased as the side airbag apparatus restrains the lumbar region PP of the occupant P, the check valve75restricts the inflation gas in the third inflation chamber63from flowing back to the first inflation chamber61. The lumbar region PP, which has a high impact resistance in the upper body of the occupant P, is effectively restrained and protected against impact by the third inflation chamber63, of which the internal pressure is high. Also, the internal pressure of the first inflation chamber61is unlikely to be increased under the influence of pressure fluctuation of the third inflation chamber63that accompanies the restraint of the lumbar region PP.

The first embodiment as described above has the following advantages.

(1) The inflation portion46of the airbag main body41is divided into the first inflation chamber61, the second inflation chamber62, which is located in front of the first inflation chamber61with the vertical partition81having the communication hole94in between, and the third inflation chamber63, which is located below the first and second inflation chambers61,62with the lateral partition64in between and is inflated beside the lumbar region PP of the occupant P. The airbag main body41has in it the gas passage100, which extends in the up-down direction and surrounds at least the gas outlet31aof the inflator31. The gas passage100bridges the first inflation chamber61and the third inflation chamber63. The gas passage100has at its upper end the upper opening114, which faces a part of the first inflation chamber61that is inflated beside the shoulder region PS of the occupant P. The gas passage100also has at its lower end the lower opening74, which faces the third inflation chamber63(FIG. 5(a)).

Therefore, it is possible to promptly supply inflation gas to the portions of the airbag main body41that are inflated beside the shoulder region PS and the lumbar region PP of the occupant P, thereby promptly restraining and protecting the shoulder region PS and the lumbar region PP.

(2) Since the lateral partition64is located in a lower part of the airbag main body41, so that the volume of the third inflation chamber63is set to be less than the total volume of the first inflation chamber61and the second inflation chamber62(FIG. 5 (a)). This allows the third inflation chamber63to be further quickly deployed and inflated.

(3) The lower opening74has the check valve75, which regulates the flow of inflation gas from the third inflation chamber63to the first inflation chamber61(FIG. 5 (a)). Therefore, the lumbar region PP, which has a high impact resistance in the upper body of the occupant P, is effectively restrained and protected against impact by the third inflation chamber63, of which the internal pressure is maintained high.

(4) The gas passage100is formed by an inner tube101, which extends in the up-down direction in a rear portion of the airbag main body41and intersects the lateral partition64. The inner tube101is joined to the lateral partition64by the joint portions76,77, the peripheral joint portion45, and the center joint portion111(FIGS. 6 to 8).

Therefore, the gas passage100is formed by a simple structure in which the inner tube101, which extends in the up-down direction, is located in a rear portion of the airbag main body41and joined by the joint portions76,77,45,111to the lateral partition64, which extends between the main body fabric portions43,44of the airbag main body41.

(5) The upper opening114of the gas passage100is formed to have a smaller flow resistance against inflation gas than that of the communication hole94of the vertical partition81(FIGS. 5(a)and6).

Therefore, the section of the first inflation chamber61that is inflated beside the shoulder region PS can be deployed and inflated at an earlier stage than other sections of the first inflation chamber61and the second inflation chamber62.

(6) The inflator31has an elongated shape and the gas outlet31aat one end. The inflator31is arranged so that it extends substantially in the up-down direction and the gas outlet31ais located at the lower end (FIG. 5(a)).

Therefore, inflation gas can be preferentially supplied to the third inflation chamber63from the lower opening74of the gas passage100so that the internal pressure of the third inflation chamber63is increased promptly.

Second Embodiment

A side airbag apparatus according to a second embodiment will now be described with reference toFIGS. 21 to 25.

As shown inFIGS. 21 and 22, the side airbag apparatus according to the second embodiment is the same as that of the first embodiment in that an airbag40has an airbag main body41, a lateral partition64, a vertical partition81, and an inner tube101. The second embodiment is different from the first embodiment in that a check valve75is formed only in the inner tube101, but not in the lateral partition64.

More specifically, although the inner tube101has extensions105,108, the lateral partition64has no extensions like the extensions68,71of the first embodiment as shown inFIG. 6. Accordingly, the lateral partition64does not have the joint portions76,77or the peripheral joint portion45. A joint portion116is formed along front peripheries of the folded extensions105,108. The joint portion116, which replaces the joint portion76of the first embodiment, is located below the peripheral joint portion112and joins front peripheral portions of the extensions105,108with each other.

A part of the inner side extension105that is surrounded by the lower opening74and the joint portions116,77form a valve body78on the inner side of the check valve75. Also, a part of the outer side extension108that is surrounded by the lower opening74and the joint portions116,77form a valve body79on the outer side of the check valve75.

Further, the inner tube101and the lateral partition64joined to each other at a position directly above the valve bodies78,79by a joint portion115, which extends in a direction substantially perpendicular to the folding lines65,102. The opposite ends of the joint portion115pass through between the peripheral joint portion112and the joint portion116and are located in the vicinity of the side edges of the inner tube101. When the valve bodies78,79function as the check valve75, the joint portion115restricts backflow of inflation gas in the third inflation chamber63to the first inflation chamber61through the clearance between the inner tube101and the lateral partition64.

The airbag40of the side airbag apparatus according to the second embodiment is constructed as described above. A method for manufacturing the airbag40will now be described. The differences from the first embodiment will mainly be discussed.

Prior to the first joining step, a step in which the inner tube101is joined to the lateral partition64is performed as shown inFIG. 23. In this step, the lateral partition64is spread together with the inner tube101. With the folding line102matched with the folding line65, the lower part of the inner tube101is overlaid on to the center part of the lateral partition64. At a position directly above the extensions105,108, the inner tube101is sewn to the lateral partition along a line perpendicular to the folding line102, so that the joint portion115is formed. The joint portion115joins the inner tube101to the lateral partition64at a position directly above the extensions105,108.

In the first joining step, the outer joint portion72, which joins the lateral partition64to the airbag main body41, is formed. The joining operation is performed in a state in which the part of the lateral partition64where the outer joint portion72is to be formed is exposed, for example, by bending a part of the inner tube101that is above the joint portion115forward, or in a direction away from the lateral partition64.

As shown inFIG. 25, a center joint portion111for joining the spread inner tube101to the airbag main body41is formed in the second joining step. Bolt holes109and a slit113are formed in the inner tube101.

Further, the inner tube101is folded forward in half along the folding line102as in the case ofFIG. 9, and the structural fabric portion103and the structural fabric portion106are overlaid onto each other. The main body forming fabric portions104,107are sewn to each other at the facing peripheral portions, so that the peripheral joint portion112is formed. The peripheral joint portion112joins the main body forming fabric portions104,107to each other. The extensions105,108are sewn to each other at the facing peripheral portions, so that the joint portion116is formed. The joint portion116joins the extensions105,108to each other.

Thereafter, the third to fourth joining steps are performed in the same manner as illustrated in the first embodiment.

However, the joint portion76is not formed in the fourth joining step. This is because the extensions68,71are omitted from the lateral partition64, and the joint portion116, which joins the front peripheral portions of the extension105,108to each other, has already been formed.

Other than these differences, the second embodiment is the same as the first embodiment. Therefore, like or the same reference numerals are given to those components that are like or the same as the corresponding components of the first embodiment and detailed explanations are omitted.

According to the side airbag apparatus of the second embodiment, which has the above described structure, the valve bodies78,79of the inner tube101function as the check valve75as shown inFIG. 21.

The inflation gas that is discharged from the gas outlet31aof the inflator31and ejected downward from the lower open end32aand the inflation gas the direction of which has been changed to the downward direction by the inner tube101after being discharged from the gas outlet31aflow to the lower end of the gas passage100. When reaching the lower end, the inflation gas flows to the third inflation chamber63from the lower opening74via the check valve75of the inner tube101. The inflation gas is thus promptly supplied to the third inflation chamber63.

When the discharge of inflation gas from the inflator31stops and the inflation gas in the third inflation chamber63acts to flow to the first inflation chamber61, the valve bodies78,79are pushed by the high pressure in the third inflation chamber63and contact each other, so that the check valve75is closed. Also, the inner tube101is joined to the lateral partition64by the joint portion115, which is located directly above the extensions105,108, and there is no clearance between the inner tube101and the lateral partition64. This restricts the inflation gas in the third inflation chamber63from flowing back to the first inflation chamber61.

Thus, the second embodiment has the following advantage in addition to the above described advantages (1) to (6).

(7) The check valve75is formed only by the extensions105,108of the inner tube101(FIGS. 21 and 22).

This simplifies the structure of the check valve75. Further, since the extensions68,71are omitted from the lateral partition64, the shape of the lateral partition64is simplified. The lateral partition64can thus be easily formed.

Third Embodiment

A side airbag apparatus according to a third embodiment will now be described with reference toFIGS. 26 to 30.

As shown inFIGS. 26 and 27, the side airbag apparatus according to the third embodiment is the same as that of the first and second embodiments in that an airbag40has an airbag main body41, a lateral partition64, a vertical partition81, and an inner tube101. The third embodiment is different from the first and second embodiments in that the check valve75and the pressure regulator valve97are not provided.

More specifically, the lateral partition64, which is elongated in the lateral direction, is folded in half along a folding line65formed in the center portion. The lateral partition64is placed between the main body fabric portions43,44of the airbag main body41with the folding line65matched with the folding line82of the vertical partition81. The extensions68,71and the joint portions76,77,116are not formed in the lateral partition64.

The vertical partition81is formed by a single fabric piece that extends substantially in the up-down direction, and its upper end is overlaid onto the upper end of the airbag main body41, and its lower end is overlaid onto the rear end of the lateral partition64. A pair of communication holes94, which is always open, is formed in the center portion in the up-down direction of the vertical partition81. The vertical partition81does not have the pressure regulator valve97.

The upper opening114of the gas passage100is formed to have a smaller flow resistance of inflation gas than that of the communication holed94of the vertical partition81. Therefore, the flow passage area of the upper opening114is set to be greater than that of the communication hole94.

In the inflation portion46, the chamber rearward of the vertical partition81and the lateral partition64forms the first inflation chamber61. The chamber that is forward of the vertical partition81and above the lateral partition64forms the second inflation chamber62. The chamber below the lateral partition64forms the third inflation chamber63.

The inner tube101does not have the extensions105,108. The lower end of the inner tube101is overlaid onto the rear lower end of the airbag main body41. The lower end of the peripheral joint portion112, which joins the main body forming fabric portion104,107of the folded the inner tube101to each other, is located at a position that is separated upward from the lower end of the inner tube101by a predetermined distance. That is, the lower ends of the main body forming fabric portion104,107are not joined to each other by the peripheral joint portion112, and this section serves as the lower opening74, which opens toward the third inflation chamber63.

The airbag40of the side airbag apparatus according to the third embodiment is constructed as described above. A method for manufacturing the airbag40will now be described. The differences from the first and second embodiments will mainly be discussed.

A great difference from the first and second embodiment is that the step for temporarily attaching the inner tube101to the airbag main body41and the step for joining the lateral partition64to the airbag main body41by the outer joint portion72are performed in reverse order of the order of the first and second embodiments.

That is, the airbag main body41and the inner tube101are spread as shown inFIG. 28. With the folding line102matched with the folding line42, the inner tube101is overlaid onto the airbag main body41. The lower end of the inner tube101is sewn to the lower end of the airbag main body41, more specifically, to a part in the vicinity of a part where the peripheral joint portion45is to be formed. This forms the joint portion115. The joint portion115temporarily attaches the lower end of the inner tube101to the lower end of the airbag main body41, while determining the relative positions. In the inner side structural fabric portion103, the bolt holes109are formed at positions that correspond to the bolt holes52of the main body fabric portion43. The slit113is formed in the inner side structural fabric portions103,106at a position that corresponds to the slit47of the airbag main body41.

As indicated by the arrow of a broken line in which long dash alternates with a pair of short dashes inFIG. 28, the inner tube101is folded in half along the folding line102, and the structural fabric portion103and the structural fabric portion106are overlaid onto each other. The main body forming fabric portions104,107are sewn to each other at the facing peripheral portions, so that the peripheral joint portion112is formed. The peripheral joint portion112joins the main body forming fabric portions104,107to each other to form a tubular shape.

Subsequently, as shown inFIG. 29, the rear part of the airbag main body41and the inner tube101are folded forward in half along the folding lines42,102. The airbag main body41is spread except for the rear part.

The spread lateral partition64is overlaid onto airbag main body41, part of which is spread as described above. Specifically, the inner side structural fabric portion66is overlaid onto the lower part of the corresponding main body fabric portion43, and the outer side structural fabric portion69is overlaid onto the lower part of the corresponding main body fabric portion44.

The inner side main body forming fabric portion67is sewn at its upper peripheral portion to the lower part of the main body fabric portion43, and the outer side main body forming fabric portion70is sewn at its upper peripheral portion to the lower part of the main body fabric portion44. The outer joint portion72is thus formed.

Subsequently, as shown inFIG. 30, the spread vertical partition81is overlaid onto the partly spread airbag main body41and the partly spread lateral partition64.

Parts of the peripheries of the vertical partition81that are not overlaid on the structural fabric portions66,69are sewn to the main body fabric portions43,44, so that a pair of the outer joint portions84is formed.

Also, parts of the peripheries that are overlaid on the structural fabric portions66,69are sewn only to the main body forming fabric portions67,70, so that a pair of the outer joint portions85is formed below the outer joint portions84.

The outer joint portions84may be formed either before or after the outer joint portions85are formed.

Thereafter, the fourth and fifth joining steps are performed in the same manner as illustrated in the first embodiment.

However, in the fourth joining step, the lower peripheries of the main body forming fabric portions67,70are sewn to each other to form the inner joint portion73. The joint portion76is not formed. The main body forming fabric portions67,70are joined to each other by the inner joint portion73, and the lateral partition64extends between the main body fabric portions43,44.

Other than these differences, the third embodiment is the same as the first and second embodiments. Therefore, like or the same reference numerals are given to those components that are like or the same as the corresponding components of the first and second embodiments and detailed explanations are omitted.

According to the above described side airbag apparatus, the inflation gas that is discharged from the gas outlet31aand ejected downward from the lower open end32aand the inflation gas the direction of which has been changed to the downward direction by the inner tube101after being discharged from the gas outlet31aflow to the lower end of the gas passage100. When reaching the lower end, the inflation gas is supplied to the third inflation chamber63from the lower opening74.

Since the check valve75is not formed, the inflation gas in the third inflation chamber63may flow back to the first inflation chamber61when the ejection of inflation gas from the inflator31is stopped. Therefore, in the third embodiment, an additional means needs to be introduced for maintaining the internal pressure of the third inflation chamber63at a high level when desired.

Thus, the third embodiment has the same advantages as the above described advantages (1), (2), (5), and (6).

The above embodiments may be modified as follows.

The substantially entire airbag40may be formed of the inflation portion46as in the above-illustrated embodiment, but may also partially include a non-inflation portion, which neither supplied with inflation gas nor inflated.

In place of the tether extending between the main body fabric portions43and44of the airbag main body41, the lateral partition64may be formed by a seam that is generated by bringing the main body fabric portions43,44in contact with each other and sewing (joining) these together.

The check valve75may be formed by a member separate from the lateral partition64and the inner tube101.

<Regarding Vertical Partition81of First and Second Embodiments>

The peripheries of the vertical partition81may be joined to the main body fabric portions43,44either inside the first inflation chamber61or inside the second inflation chamber62.

Also, one of the peripheries may be joined inside the first inflation chamber61, and the other periphery may be joined inside the second inflation chamber62.

Parts of the overlapping portions91that correspond to the communication hole94(parts in the vicinity of the communication hole94, or more accurately, parts between the communication hole94and the edges88e,89e) function as the valve bodies95,96. Therefore, as long as at least the distal ends95t,96tof the valve bodies95,96are in contact with each other and are closed when the first inflation chamber61is deployed and inflated, parts of the overlapping portions91that do not correspond to the communication hole94(parts not in the vicinity) may be modified. For example, parts of the overlapping portions91that do not correspond to the communication hole94(parts not in the vicinity) may be joined partially or entirely. The joining means may be sewing or adhering. According to this modification, only parts of the overlapping portions91that correspond to the communication hole94operate as the valve bodies95,96, and parts of the overlapping portions91that do not correspond to the communication hole94are prevented from unnecessarily moving, for example, flapping.

Furthermore, a cutout may be formed at least at part of the portion of the overlapping portions91that does not correspond to the communication hole94.

The vertical partition81may be formed by a member different from the members forming the valve bodies95,96.

The portion to be disjoined is canceled in the inner joint portion93does not necessarily have to be provided at a portion that extend across the folding line82, but may be provided at a portion displaced away from the folding line82in the direction perpendicular to the folding line82. Also, the inner joint portions93may be disjoined at two or more positions.

The overlapping portions91, which include the valve bodies95,96, may be provided in the second inflation chamber62instead of the first inflation chamber61, prior to deployment and inflation of the inflation portion46.

The vertical partition81, which is folded in half, may be provided in the inflation portion46in the uninflated and deployed state with the folding line82located downstream of the peripheral portions. In this case, the overlapping portions91, which have the valve bodies95,96, may be located in the second inflation chamber62before the inflation portion46is deployed and inflated.

The vertical partition81may have a shape different from that in the above illustrated embodiment. In this case, the outer shape of the vertical partition81is preferably changed in accordance with a part of the upper body of the occupant P to be restrained and protected by the first inflation chamber61. Accordingly, the structure of the outer joint portion84, which joins the vertical partition81to the main body fabric portions43,44, is different from that in the above illustrated embodiment. For example, when protecting the shoulder region PS of the occupant P in a wider area, the outer joint portion84may be provided forward of its position in the above illustrated embodiments. For example, a part of the outer joint portion84that joins the upper fabric piece86to the main body fabric portions43,44may be inclined forward toward the upper end.

The pressure regulator valve97may be omitted, and the communication hole94may be modified to have the same structure as that in the third embodiment (a hole that is always open).

The communication hole94may be modified to have the same structure as that in the first and second embodiments (a hole that is selectively opened and closed) to additionally form a pressure regulator valve97.

Instead of the seat back14of the automobile seat12, a part that corresponds to the storage portion21may be located in the side wall portion11to accommodate the airbag module AM.

The shape of the inner tube101may be changed as long as the following conditions are satisfied.

Condition 1: The inner tube101encompasses at least the gas outlet31aof the inflator31.

Condition 2: The inner tube101extends substantially in the up-down direction while intersecting with the lateral partition64and bridges the first inflation chamber61and the third inflation chamber63.

Thus, the inner tube101may, for example, encompass the entire inflator31.

The present invention may be applied to a side airbag apparatus of an automobile in which a seat12that faces in a direction other than the forward direction, for example, sideways. In this case, when an impact is applied to a side of the automobile seat12(in the front-rear direction of the automobile), the side airbag apparatus protects an occupant P from the impact.

Automobiles to which the side airbag apparatus according to the present invention is applied include various industrial vehicles in addition to private cars.

The above described side airbag apparatus may also be applied to an airbag apparatus installed in the seats in vehicles other than automobiles, including aircrafts and ships.