Airbag apparatus

A check valve 60 is formed by a pair of the valve body portions 61. Ends of the valve body portions 61 that are close to an upper inflation portion EU are joined to a communication passage wall 51 by an outflow-side joint portion 41. Each valve body portion 61 includes a flexible portion 64 that is located in the vicinity of the outflow-side joint portion 41 and between the outflow-side joint portion 41 and a lower inflation portion EL. The front edges of the valve body portions 61 are joined to the communication passage wall 51 by a first edge joint portion 67. The first edge joint portion 67 also functions as a wall joint portion 63 that joins the communication passage walls 51 to each other. The rear ends of the valve body portions 61 are joined to each other by a second edge joint portion 68, which extends along the flowing direction of inflation gas. An auxiliary joint portion 69 is located between the first edge joint portion 67 and the second edge joint portion 68, and in the vicinity of the second edge joint portion 68. The auxiliary joint portion 69 joins the valve body portions 61 to each other. The auxiliary joint portion 69 also functions as a rigid portion 65, which is harder to flex than the flexible portion 64. The rigid portion 65 extends along the flowing direction of the inflation gas.

BACKGROUND OF THE INVENTION

The present invention relates to an airbag apparatus that inflates an airbag to protect an occupant when an impact is applied to a vehicle.

As apparatuses for protecting an occupant from impact applied to a vehicle, airbag apparatuses having a gas generator (inflator) and an airbag are widely known. Such airbag apparatuses include side airbag apparatuses that protect an occupant from an impact applied to a vehicle from a side. In this type of apparatus, when an impact is applied from a side of a body side portion of a vehicle, a gas generator discharges inflation gas into the airbag. The discharged inflation gas causes the airbag to pop out forward from the seat back and to be inflated and deployed in a narrow space between the occupant seated in the vehicle seat and the body side portion. The inflated airbag reduces the impact that is transmitted from the side to the occupant through the body side portion.

In general, the lumbar region of the human body has a higher impact resistance than the shoulders and thorax. Thus, in a case of a side airbag apparatus for protecting a region including a shoulder and the lumbar region, it is preferable that the impact applied to the shoulder and thorax by the airbag be less than impact applied to the lumbar region.

For example, according to the side airbag apparatus disclosed in Japanese Patent No. 4103633, the interior of the airbag is divided into an upper inflation portion that corresponds to a shoulder and the thorax and a lower inflation portion that corresponds to the lumbar region. The upper and lower inflation portions are connected with each other by a communication passage. A cylindrical gas distributor, which encompasses a gas generator, is provided in the communication passage. The gas distributor includes an upper gas port for discharging inflation gas from the gas generator to the upper inflation portion and a lower gas port for discharging the inflation gas to the lower inflation portion. Since the lower gas port is larger than the upper gas port in this side airbag apparatus, a greater amount of inflation gas is supplied to the lower inflation portion by the gas distributor than to the upper inflation portion. Thus, the lower inflation portion is inflated at an earlier stage and by a higher internal pressure than the upper inflation portion. Accordingly, the lower inflation portion of the airbag is inflated to be relatively hard, and the upper inflation portion is inflated to be relatively soft. This allows an occupant to be effectively protected from an impact.

Further, the gas distributor of the side airbag apparatus disclosed in Japanese Patent No. 4103633 is formed of fabric. A lower portion of the gas distributor extends further downward than the lower end of the gas generator and forms a check valve. When the body of the occupant hits the lower portion of the inflated airbag, the internal pressure of the lower inflation portion is increased. When, as the result, the inflation gas starts flowing to the upper inflation portion through the gas distributor, the lower portion of the gas distributor overlaps onto itself and is closed. This restricts the flow of the inflation gas to the upper inflation portion.

However, in the above described side airbag apparatus, in which the lower portion of the cylindrical gas distributor is a check valve, parts that face the lower portion of the gas distributor are simply caused to overlap by the pressure of the inflation gas. In this case, the parts facing the gas distributor cannot be easily tightly closed without clearance, and it is therefore difficult to completely close the flow passage of the inflation gas. If the lower portion of the gas is open by the smallest degree, the inflation gas flows through the clearance. Also, when the internal pressure of the lower inflation portion is excessively high, the lower portion of the gas distributor receives a high pressure. As a result, the lower portion of the gas distributor may be tucked inside and inverted. In this case also, the inflation gas flows to the upper inflation portion through the gas distributor. As described so far, the check valve of the side airbag apparatus disclosed in Japanese Patent No. 4103633 does not operate in a stable manner.

SUMMARY OF THE INVENTION

Accordingly, it is an objective of the present invention to provide an airbag apparatus capable of allowing a check valve to operate reliably with a simple structure.

To achieve the foregoing objective and in accordance with one aspect of the present invention, an airbag apparatus comprising an airbag and a check valve is provided. The airbag has a plurality of inflation portions inflated by inflation gas. An adjacent pair of the inflation portions are connected to each other by a communication passage formed by a pair of communication passage walls. The check valve has a pair of valve body portions provided in the communication passage. One of the inflation portions is a gas inflow inflation portion, which is inflated and deployed by a relatively high internal pressure. Another inflation portion is a gas outflow inflation portion, which is inflated and deployed by an internal pressure that is lower than that of the gas inflow inflation portion. The check valve restricts flow of the inflation gas from the gas inflow inflation portion to the gas outflow inflation portion. End portions of the valve body portions that are in the vicinity of the gas outflow inflation are each connected to corresponding one of the communication passage wall by an outflow-side joint portion extending in a direction intersecting a direction in which the inflation gas flows through the communication passage. Each valve body portion has a flexible portion that is located in the vicinity of the outflow-side joint portion and between the outflow-side joint portion and the gas inflow inflation portion. The flexible portion can be flexed toward the gas outflow inflation portion. A first edge joint portion is provided on a side edge of one of the valve body portions. The first edge joint portion is used for joining the valve body portion to the corresponding communication passage wall. A wall joint portion is provided on or in the vicinity of the first edge joint portion. The wall joint portion is used for joining the communication passage walls to each other. A second edge joint portion is provided on a side edge of the other valve body portion. The second edge joint portion is used for joining the valve body portions to each other, and the second edge joint portion extends along the flowing direction of the inflation gas. An auxiliary joint portion is provided in the vicinity of the second edge joint portion and between the first edge joint portion and the second edge joint portion. The auxiliary joint portion is used for joining the valve body portions to each other, and the auxiliary joint portion extends from the vicinity of the flexible portions toward the gas inflow inflation portion. A rigid portion, which is harder to flex than the flexible portion, is provided on or in the vicinity of the auxiliary joint portion. The rigid portion extends along the flowing direction of the inflation gas.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

A side airbag apparatus according to a first embodiment of the present invention will now be described with reference toFIGS. 1 to 16. Hereinafter, the traveling direction of the vehicle is referred to as a forward direction.

As shown inFIGS. 1 and 3, a vehicle seat12is arranged in the vicinity of a body side portion11of the vehicle. The body side portion11refers to a member that is located at a side of the vehicle. For example, part of the body side portion11corresponding to the front seat includes a front door, and a center pillar (B-pillar). Part of the body side portion11corresponding to the rear seat includes a rear part of the side door (rear door), a rear pillar (C-pillar), a front part of the wheel well, and a rear quarter.

The vehicle seat12includes a seat cushion (seat portion)13and a seat back (backrest portion)14. The seat back14extends upward from the rear end of the seat cushion13and includes a tilt adjusting mechanism (not shown). A storage portion15is provided in a side portion of the seat back14. The storage portion15accommodates an airbag module AM, which forms a main part of the side impact airbag apparatus. The storage portion15is located diagonally behind an occupant P seated on the vehicle seat12. The airbag module AM includes an inflator assembly20(seeFIG. 5), which serves as a gas supply source, and an airbag30. The airbag30is inflated by inflation gas G supplied by the inflator assembly20.

The members forming the side airbag apparatus will now be described. In the present embodiment, the up-down direction and the front-rear direction are defined with reference to the seat back14of the vehicle seat12. That is, the up-down direction refers to the direction along which the seat back14stands, and the front-rear direction refers to a direction along the thickness of the seat back14. The seat back14is normally inclined rearward when used. The term “up-down direction” here is therefore not vertical, but is slightly inclined. Likewise, the front-rear direction is not strictly a horizontal direction, but is slightly inclined.

As shown inFIGS. 4 and 6, the inflator assembly20includes an inflator21and a retainer22that covers the inflator21. The inflator21is substantially formed like a thin column extending along the up-down direction. The inflator21stores a gas generating agent (not shown). The gas generating agent generates the inflation gas G in response to an actuation signal from the outside.

A harness (not shown) for sending actuation signals of the inflator21is connected to an upper portion of the inflator21. A substantially cylindrical gas nozzle23is provided in a lower portion of the inflator21. The diameter of the gas nozzle23is smaller than that of the remainder of the inflator21. A plurality of gas ports24are formed on the outer circumferential surface of the gas nozzle23. The inflation gas G is discharged along a direction perpendicular to the axis L of the inflator21, through the gas ports24. The inflator21may be a type that has a compressed gas cylinder, in which a partition wall is broken with explosive to discharge inflation gas G.

The retainer22functions as a diffuser. Also, the retainer22secures the inflator21to a seat frame16in the seat back14together with the airbag30. Most of the retainer22is formed by bending a metal plate into a thin cylinder extending along the up-down direction. The retainer22has an open end22A at the lower end. Some of the inflation gas G discharged from the gas nozzle23is blown through the open end22A.FIG. 5shows a state in which a part is cut away from the retainer22, so that the open end22A is visible.

The retainer22has a window25at a portion above the open end22A and in the vicinity of the gas nozzle23of the inflator21. Through the window25, the inflation gas G discharged from the gas nozzle23is blown forward.

Two bolts26for fixing the retainer22to the seat frame16are fixed to the retainer22. The bolts26are indirectly fixed to the inflator21by means of the retainer22. The bolts26extend in a direction perpendicular to the axis L of the inflator21. The inflator21and the retainer22of the inflator assembly20may be an integrated member.

As shown inFIGS. 1 to 3, when an impact is applied to the body side portion11from a side, the airbag30is inflated and deployed by the inflation gas G from the inflator21(seeFIGS. 5 and 6). The airbag30pops out toward the front of the vehicle with a part thereof retained in the storage portion15. Thereafter, the airbag30is inflated and deployed in a space G1between the vehicle seat12and the body side portion11to restraining the occupant P, thereby protecting the occupant P from the impact.

As shown inFIGS. 4 and 7, the airbag30is formed by a fabric panel (ground fabric sheet)31, which is a single fabric sheet. As the material for the fabric panel31, a material that has a high strength and flexibility and is easy to fold is preferable. For example, woven fabric made of polyester threads or polyamide threads is suitable.

As shown inFIGS. 7 and 8, a folding line32is defined at a center of the fabric panel31. The fabric panel31is folded into half at the folding line32so as to overlap onto itself. The rear edge30R of the half folded airbag30is arranged to match the folding line32. A part of the fabric panel31that is located on the vehicle inner side is referred to as a fabric portion33, and a part located on the vehicle outer side is referred to as a fabric portion34. The fabric portions33,34are symmetrically arranged with respect to the folding line32. The shapes and sizes of the fabric portions33,34are determined to cover a wide range of the occupant P seated on the vehicle seat12, which extends from the lumbar region PP to the thorax PT and a shoulder PS. The airbag30may be formed by two fabric panels.

A reinforcing fabric sheet35is provided at a center of the fabric panel31to increase the strength of the fabric portions33,34against the heat of the inflation gas G. The reinforcing fabric sheet35spreads into the fabric portions33,34with the folding line32as the center. The reinforcing fabric sheet35is formed of a single fabric sheet, and includes a fabric portion36located on the fabric portion33, and a fabric portion37located on the fabric portion34. The reinforcing fabric sheet35may be formed by two fabric sheets.

The fabric portion36of the reinforcing fabric sheet35is joined to the fabric portion33of the fabric panel31by an inner joint portion38. Likewise, the fabric portion37of the reinforcing fabric sheet35is joined to the fabric portion34of the fabric panel31by an inner joint portion39. When the airbag30and the reinforcing fabric sheet35are spread, the inner joint portions38,39form a substantially U-shape together. The lower end of the inner joint portion38extends straight along the front-rear direction. The lower end of the inner joint portion38forms a first outflow-side joint portion41. The lower end of the inner joint portion39also extends straight along the front-rear direction. The lower end of the inner joint portion39forms a second outflow-side joint portion42. The first and second outflow-side joint portions41,42extend in a direction substantially perpendicular to the direction in which the inflation gas G in a communication passage50flows (up-down directionFIGS. 7 and 8). The inner joint portion38is formed by sewing the fabric portions33,36with sewing threads. The inner joint portion39is formed by sewing the fabric portions34,37with sewing threads.

InFIGS. 4,7,8,9,12to16,22,23,24, and25, the thick dashed lines represent sewing threads on the outer surface of the fabric, and the dotted lines represent sewing threads on the inner surface of the fabric, that is, the sewing threads between fabric sheets. That is, the drawings showing the latter are cross-sectional views taken along a plane including sewn parts. The inner joint portions38,39may be formed by adhesive. This applies to the elements that will be discussed below, including a peripheral joint portion43, a dividing joint portion44, the inner joint portions38,39, the outflow-side joint portions41,42, a wall joint portion63, a first edge joint portion67, an auxiliary joint portion69, and rigid portions65.

As shown inFIGS. 4 and 7, the fabric portions33,36and the fabric portions34,37are joined by the peripheral joint portion43located at the periphery except for their rear edges. Portions of the fabric portion33,36and the fabric portions34,37that are encompassed by the peripheral joint portion43are inflated by the inflation gas G.

The fabric portions33,34of the fabric panel31and the fabric portions36,37of the reinforcing fabric sheet35are joined to each other by the dividing joint portion44, which is a part of the peripheral joint portion43. The dividing joint portion44divides the airbag30into a lower inflation portion having a relatively small volume and an upper inflation portion having a volume greater than that of the lower inflation portion. The dividing joint portion44includes a pair of extensions45and a connecting portion46that connects the rear ends of the extensions45. The extensions45are separated from each other and extend rearward from the front ends of the fabric portions33,34,36,37. The connecting portion46includes a projection47projecting rearward. Further, the fabric portions33,36on the vehicle inner side and the fabric portions34,37on the vehicle outer side are joined to each other by a rear portion43A of the peripheral joint portion43.

An inflation portion below the dividing joint portion44is formed as a lower inflation portion EL that is inflated and deployed by a relatively high internal pressure to restrain and protect the lumbar region PP of the occupant P. Also, an inflation portion above the dividing joint portion44is formed as an upper inflation portion EU that is inflated and deployed by an internal pressure lower than that of the lower inflation portion EL to protect the thorax PT of the occupant P, more specifically, to protect a part from the abdomen PB to the shoulder PS. The lower inflation portion EL is a gas inflow inflation portion, and the upper inflation portion EU is a gas outflow inflation portion.

The connecting portion46is located forward of the rear edge30R of the airbag30. The communication passage50is located in the airbag30to connect the lower inflation portion EL and the upper inflation portion EU to each other, and to allow the inflation gas G to flow therethrough. The communication passage50is formed by a space that is located between the fabric portions33,36on the vehicle inner side and the fabric portions34,37on the vehicle outer side, and between the rear edge30R and the connecting portion46. Parts of the fabric portions33,36on the vehicle inner side that form the communication passage50are defined as a first communication passage wall51, and parts of the fabric portions34,37on the vehicle outer side that form the communication passage50are defined as a second communication passage wall52(seeFIGS. 8 and 11). The first and second communication passage walls51,52are flat and laid on top of each other when the airbag30is not inflated.

As shown inFIG. 9, in the communication passage50, the distance between the rear edge30R and the connecting portion46of the airbag30is smallest at a distal end47T of the projection47. The peripheral joint portion43including the dividing joint portion44is formed by sewing the fabric portions33,36on the vehicle inner side and the fabric portions34,37on the vehicle outer side with sewing threads. A portion of the airbag30that is surrounded by the upper and lower extensions45and the connecting portion46is a non-inflation portion48, which is not inflated.

As shown inFIG. 4, the inflator assembly20is provided in the airbag30at a position in the vicinity of the communication passage50, while being inclined to be lower toward the front end. The lower end of the inflator assembly20is located rearward of the connecting portion46. Most of the inflator assembly20is located above the connecting portion46.

The bolts26fixed to the retainer22are inserted into the rear portions of the fabric portions33,36on the vehicle inner side (seeFIGS. 5 and 6). A part in the vicinity of the peripheral joint portion43A of the airbag30is airtightly fastened to the upper end of the inflator assembly20by an annular fastening tool (not shown) attached to the outside of the airbag30. As shown inFIGS. 9 to 11, the communication passage50includes a check valve60, which restricts the flow of the inflation gas G from the lower inflation portion EL to the upper inflation portion EU.

As shown inFIGS. 7 and 8, the check valve60is formed by a single fabric sheet58. The fabric sheet58is arranged to spread into the fabric portions33,34,36,37of the fabric panel31and the reinforcing fabric sheet35with the folding line32as the center. A folding line59is formed in a center portion of the fabric sheet58. The fabric sheet58is folded in the middle along the folding lines32,59with the fabric panel31and the reinforcing fabric sheet35, while matching the folding line59with the folding line32of the fabric panel31. A part of the fabric sheet58that is located on the vehicle inner side is referred to as a first valve body portion61, and a part of the fabric sheet58that is located on the vehicle outer side is referred to as a second valve body portion62. The check valve60is formed by a pair of the valve body portions61,62.

The valve body portions61,62are joined to the reinforcing fabric sheet35and the airbag30by using parts of the inner joint portions38,39and a part of the dividing joint portion44. The lower end of the inner joint portion38, which is used for joining the first valve body portion61to the reinforcing fabric sheet35and the airbag30, is the first outflow-side joint portion41, which extends along the front-rear direction, which is substantially perpendicular to the flowing direction of the inflation gas G through the communication passage50. Likewise, the lower end of the inner joint portion39, which is used for joining the second valve body portion62to the reinforcing fabric sheet35and the airbag30is the second outflow-side joint portion42, which extends along the front-rear direction, which is substantially perpendicular to the flowing direction of the inflation gas G through the communication passage50.

The upper end of the first valve body portion61is joined to the first communication passage wall51by the first outflow-side joint portion41on the vehicle inner side. The upper end of the second valve body portion62is joined to the second communication passage wall52by the outer second outflow-side joint portion42. In this case, the first outflow-side joint portion41is formed by sewing the first valve body portion61of the check valve60and the fabric portion36of the reinforcing fabric sheet35to the fabric portion33of the fabric panel31. Also, the second outflow-side joint portion42is formed by sewing the second valve body portion62of the check valve60and the fabric portion37of the reinforcing fabric sheet35to the fabric portion34of the fabric panel31. The upper end of the first valve body portion61and the upper end of the second valve body portion62are not joined to each other.

The dividing joint portion44, which is used for joining the valve body portions61,62to the reinforcing fabric sheet35and the airbag30, is mainly formed by the connecting portion46. The connecting portion46also functions as the first edge joint portion67and the wall joint portion63. The first edge joint portion67joins the front edges of the valve body portions61,62to the corresponding communication passage walls51,52. The wall joint portion63joins the communication passage walls51,52to each other on the first edge joint portion67or in the vicinity thereof. To simultaneously maintain these functions, the connecting portion46joins the valve body portions61,62to the communication passage walls51,52of the airbag30and the reinforcing fabric sheet35. In this case, the dividing joint portion44is formed by sewing the airbag30, the reinforcing fabric sheet35, and the check valve60.

The valve body portions61,62each have a flexible portion64, which is easily flexed toward the upper inflation portion EU by the pressure of the inflation gas G. The flexible portions64are located between the outflow-side joint portions41,42and the lower inflation portion EL and in the vicinity of the outflow-side joint portions41,42. The flexible portions64are located in a region between the outflow-side joint portions41,42and a position separated downward from outflow-side joint portions41,42by a distance L1. Specifically, each flexible portion64is a region surrounded by an alternate long and short dash line inFIG. 9.

The rear portions of the valve body portions61,62are joined together by a second edge joint portion68. The second edge joint portion68extends along the flowing direction of the inflation gas G in the communication passage50. In the present embodiment, the second edge joint portion68is formed by a folded back portion of the single fabric sheet58forming the first and second valve body portions61,62, specifically, by the folding line59and the region in its vicinity.

Further, the rigid portions65are formed at the rear portion of each of the valve body portions61,62, more specifically, at positions slightly forward of the folding line59of the fabric sheet58. The rigid portions65extend from the vicinity of the lower end of the flexible portions64toward the lower inflation portion EL at the rear portions of the valve body portions61,62. The vicinity of the lower ends of the flexible portions64include a position that is separated downward from the outflow-side joint portions41,42by the distance L1. The rigid portions65are formed by sewing the valve body portions61,62with sewing threads in a single or multiple rows. The rigid portions65are more rigid and harder to flex than the flexible portions64, the outflow-side joint portions41,42, the first edge joint portion67, and the wall joint portion63.

The rigid portions65also function as the auxiliary joint portion69. The auxiliary joint portion69is located between the first edge joint portion67and the second edge joint portion68, and in the vicinity of the second edge joint portion68. The auxiliary joint portion69joins the first valve body portion61and the second valve body portion62to each other. The auxiliary joint portion69extends toward the lower inflation portion EL from the vicinity of the lower ends of the flexible portions64, that is, from a position separated from the outflow-side joint portions41,42by the distance L1.

As described above, in the communication passage50, the distance between the rear edge30R and the connecting portion46of the airbag30is smallest at the distal end47T of the projection47. Accordingly, the distance (flow passage area DS of the inflation gas G) between the first edge joint portion67(the wall joint portion63) and the rigid portions65(the auxiliary joint portion69) is the smallest at the distal end47T of the projection47.

The rigid portions65prevent the upper ends of the communication passage walls51,52and the upper ends of the valve body portions61,62from opening. In this case, the upper ends of the communication passage walls51,52and the valve body portions61,62are more restricted as the upper ends65U of rigid portions65approach the outflow-side joint portions41,42, or as the rigid portions65approach the distal end47T of the projection47. Therefore, the upper ends65U of the rigid portions65are at positions where they do not significantly hinder the opening of the upper ends of the communication passage walls51,52and the valve body portions61,62.

As shown inFIG. 12, the rigid portions65of the check valve60are separated forward from the folding line59(the second edge joint portion68) of the fabric sheet58. Therefore, the distance D1between the folding line59and the wall joint portion63is greater than the distance between the rigid portions65and the wall joint portion63. Accordingly, when the inflation gas G flows between the valve body portions61,62so that the check valve60is opened to be cylindrical, the region between the rigid portions65and the wall joint portion63has a smaller diameter than the region between the second edge joint portion68and the wall joint portion63.

As shown inFIG. 9, the length of the rigid portions65is represented by L2. In the wall joint portion63, the distance between a spot B (the distal end47T of the projection47) at which the distance from the rigid portions65is the smallest and ends C of the outflow-side joint portions41,42is represented by D3. In the present embodiment, the expression L2>D3is satisfied.

At the lower portion of each of the valve body portions61,62, an inclined portion66, which is inclined to be higher toward the front end, is provided. At the inclined portions66, the valve body portions61,62are not joined together. The upper end of the first valve body portion61is joined to the first communication passage wall51(the fabric portions33,36on the vehicle inner side), and the upper end of the second valve body portion62is joined to the second communication passage wall52(the fabric portions34,37on the vehicle outer side). However, the upper ends of the first and second valve body portions61,62are not joined to each other. Therefore, the upper end of the check valve60and the inclined portions66can open to be cylindrical when the inflation gas G is supplied.

As shown inFIG. 10, the first valve body portion61of the check valve60is joined to the fabric portions33,36by means of the first outflow-side joint portion41. Thus, the inflation gas G does not flow between the lower inflation portion EL and the upper inflation portion EU through between the first valve body portion61and the fabric portions33,36. The second valve body portion62of the check valve60is joined to the fabric portions34,37by means of the second outflow-side joint portion42. Thus, the inflation gas G does not flow between the lower inflation portion EL and the upper inflation portion EU through between the second valve body portion62and the fabric portions34,37. That is, the inflation gas G can flow between the lower inflation portion EL and the upper inflation portion EU only through between the valve body portions61,62.

As shown inFIG. 9, a spot E, which is held between the inner joint portion38and the connecting portion46, is located between the first valve body portion61and the fabric portion33. Although the inflation gas G can flow through the spot E, the inflation force of the upper inflation portion EU causes the first valve body portion61to close contact the fabric portion33. Thus, the inflation gas G hardly flows through the portion E. A spot held between the inner joint portion39and the connecting portion46exists between the second valve body portion62and the fabric portion34. However, the inflation gas G hardly flows through the spot.

The inner joint portion38and the connecting portion46may be sewn to intersect each other. In this case, since the spot E, which functions as a flow passage of the inflation gas G, is formed, above described problems do not occur.

As shown inFIG. 9, the upper ends of the valve body portions61,62are located behind the dividing joint portion44, and face the upper inflation portion EU. Also, the inclined portions66of the valve body portions61,62are located in an upper portion of the lower inflation portion EL and rearward of the dividing joint portion44. The lower end of the retainer22is tucked into the check valve60.

As shown inFIG. 6, the airbag module AM is made compact (storage state) by folding the airbag30in a spread state (seeFIG. 4). The airbag30is folded in this manner in order that the airbag module AM can be readily stored in the narrow storage portion15in the seat back14(seeFIGS. 1 and 2).

The bolts26passed through the airbag30and the reinforcing fabric sheet35are passed through the seat frame16. A nut17is screwed onto each bolt26, so that the airbag module AM in the storage state is fastened to the seat frame16. The retainer22may be fixed to the vehicle (the seat frame16) by means of members other than the bolts26.

As shown inFIG. 1, the side airbag apparatus includes an impact sensor71and a controller72. The impact sensor71is configured by, for example, an acceleration sensor, and is attached to the body side portion11, so as to detect an impact applied to the body side portion11from the side. The controller72controls the operation of the inflator21based on a detection signal from the impact sensor71.

The operation of the side airbag apparatus as described above will now be described wither reference toFIGS. 12 to 16.FIGS. 12 to 16show changes in shape of the check valve60caused by supply of the inflation gas G and stop of the supply. InFIGS. 12 to 16, the dividing joint portion44is represented by a single broken line. Also, as indicated by frame J of an alternate long and short dash line, the folding line32of the airbag30and the folding line59of the check valve60are shown to be separate from each other in the vicinity of the rigid portions65of the outflow-side joint portions41,42. However, the folding lines32,59are actually match with each other. Therefore, the inflation gas G does not leak between the rear end of the airbag30and the rear end of the check valve60.

In the side airbag apparatus, as long as no impact is applied to the vehicle from a side, the airbag30is stored in the storage portion15with the inflator assembly20, while remaining in the storage state. At this time, the first valve body portion61and the second valve body portion62overlap onto one another.

When the impact sensor71detects that an impact the magnitude of which is greater than or equal to a predetermined value is applied to the body side portion11while the vehicle is moving, the controller72outputs an actuation signal to the inflator21. In response to the actuation signal, the gas generating agent in the inflator21generates high temperature and pressure inflation gas G. The inflation gas G is discharged along a direction perpendicular to the axis L of the inflator21, through the gas ports24of the gas nozzle23. Some of the inflation gas G flows to the upper inflation portion EU through the window25of the retainer22. Accordingly, the inflation of the upper inflation portion EU is initiated.

On the other hand, some of the inflation gas G flows to the lower inflation portion EL through the open end22A of the retainer22. In this case, the space between the inflator21and the parts of the retainer22other than the window25serves as a passage for the inflation gas G discharged from the gas ports24. The direction of the inflation gas G blown out from the gas ports24is changed to the axial direction of the inflator21(upward and downward) after the gas G hits the retainer22. However, a portion of the inflator21above the gas nozzle23has a diameter greater than that of the gas nozzle23. That is, the space between the inflator21and the retainer22is smaller than the space between the gas nozzle23and the retainer22. Therefore, the inflation gas G is hard to flow upward but easily flows downward. Thus, most of the inflation gas G that hit the retainer22flows into the check valve60through the open end22A of the retainer22.

As shown inFIG. 13, the first and second valve body portions61,62are inflated to be cylindrical while the inflation gas G is supplied to the check valve60. This is because the upper end of the first valve body portion61is joined to the first communication passage wall51, and the upper end of the second valve body portion62is joined to the second communication passage wall52(seeFIGS. 8 and 10). Also, another reason for the cylindrical inflation of the first and second valve body portions61,62is that the front edges of the valve body portions61,62are joined to the corresponding communication passage walls51,52by the first edge joint portion67. Further, the cylindrical inflation is also attributed to the fact that the rear ends of the valve body portions61,62are joined together by the auxiliary joint portion69.

When the valve body portions61,62are inflated to be cylindrical, the flexible portions64and a portion below of have different inner diameters. Also, in the check valve60, the auxiliary joint portion69is separated forward from the second edge joint portion68. Therefore, in each flexible portion64, the distance D1between the second edge joint portion68and the first edge joint portion67is greater than the distance D2between the rigid portions65and the first edge joint portion67(seeFIG. 12). Thus, portions of the valve body portions61,62that are below the flexible portions64act to inflate to be cylindrical with an inner diameter smaller than that of the flexible portions64.

However, although the front edges of the valve body portions61,62are joined to the corresponding communication passage walls51,52, whereas the rear ends of the valve body portions61,62are joined to the auxiliary joint portion69, the communication passage walls51,52are not joined to each other. Therefore, although the front edges of the valve body portions61,62are fixed to the communication passage walls51,52, the rear ends of the valve body portions61,62can move freely in relation to the communication passage walls51,52. Also, in the valve body portions61,62, the rigid portions65are rigid and hard to flex, but the flexible portions64are soft and easy to flex.

Therefore, the flexible portions64of the valve body portions61,62act to inflate to be cylindrical with a large inner diameter, and the lower part below the flexible portions64expands to be cylindrical with a small diameter. Thus, the flexible portions64are flexed toward the upper inflation portion EU. Accordingly, as indicated by arrow A inFIG. 13, portions of the valve body portions61,62that are below the flexible portions64are pulled toward the outflow-side joint portions41,42and the wall joint portion63about a region in the vicinity of the upper ends65U of the rigid portions65(a spot encompassed by frame F of an alternate long and short dash line inFIG. 14). As a result, the rigid portions65are inclined to be forward toward the lower end. At this time, the portions between the wall joint portion63and the rigid portions65are likely to be wrinkled.

The inflation gas G passes through the cylindrically inflated check valve60and flows into the lower inflation portion EL. The inflation gas G starts the inflation of the lower inflation portion EL. As the upper inflation portion EU and the lower inflation portion EL are inflated, the airbag30is unfolded in reverse order to the order when folded.

The airbag30pops out forward with a part thereof remaining in the storage portion15of the seat back14, and is inflated between the body side portion11and the vehicle seat12, while being deployed. As shown inFIGS. 3 and 4, when the airbag30is inflated and deployed, the upper inflation portion EU is inflated and deployed between the body side portion11and the thorax PT of the occupant P seated on the vehicle seat12. Also, the lower inflation portion EL is inflated and deployed between the body side portion11and the lumbar region PP of the occupant P. The body parts of the occupant P are restrained by the inflation portions EU, EL of the airbag30. In this manner, the occupant P is protected from the impact of a side collision.

The internal pressure of the upper inflation portion EU starts increasing after the internal pressure of the inner inflation portion EL starts increasing, due to difference in the flow rate and volume of the inflation gas G supplied by the inflator21. At an early stage of the inflation of the airbag30, the internal pressure of the upper inflation portion EU is lower than the internal pressure of the lower inflation portion EL. As a result, the lumbar region PP, which has a high impact resistance, is restrained and protected by the lower inflation portion EL, of which the internal pressure is high. Also, the thorax PT, which has a low impact resistance, is softly restrained and protected by the upper inflation portion EU, of which the internal pressure is low. As a result, the impact applied to the occupant P by the airbag30is smaller at the thorax PT than at the lumbar region PP.

As shown inFIG. 14, when the ejection of the inflation gas G stops, the inflation gas G in the lower inflation portion EL of a high internal pressure acts to flow to the upper inflation portion EU of a low internal pressure through the check valve60. At this time, the check valve60operates in the following manner. At the same time as the ejection of the inflation gas G stops, the flexible portions64, which are pulled toward the upper inflation portion EU based on the difference in inner diameter between the valve body portions61,62, receives the inflation gas G flowing from the lower inflation portion EL to the upper inflation portion EU and is pushed at once. The push further lifts the flexible portions64of the valve body portions61,62as indicated by arrow H inFIG. 14. Accordingly, parts of the valve body portions61,62below the flexible portions64are further pulled toward the outflow-side joint portions41,42(upward) and toward the wall joint portions63(forward).

At this time, the rigid portions65are also pulled toward the outflow-side joint portions41,42. The rigid portions65fall onto the outflow-side joint portions41,42and the wall joint portion63about a fulcrum, which is a region in the vicinity of the upper ends65U located close to the outflow-side joint portions41,42(a part encompassed by frame F). At this time, in parts of the valve body portions61,62below the flexible portions64, parts that are forward of the rigid portions65receive a high pressure applied by the inflation gas G flowing from the lower inflation portion EL toward the upper inflation portion EU. These pressure receiving parts are pressed into the space between the valve body portions61,62and further bent diagonally upward as indicated by arrow I inFIG. 15. Accordingly, the space between the valve body portions61,62, that is, the flow passage of the inflation gas G is narrowed.

In the present embodiment, the length L2of the rigid portions65is longer than the distance D3(L2>D3). Thus, when the rigid portions65are falling diagonally upward, the rigid portions65contact the projection47of the connecting portion46as shown inFIG. 16. The projection47prevents the rigid portions65from falling onto the outflow-side joint portions41,42and the wall joint portion63. In this state, since the check valve60is substantially closed, the inflation gas G in the lower inflation portion EL is prevented from flowing to the upper inflation portion EU through between the valve body portions61,62.

Therefore, the internal pressure of the lower inflation portion EL, which has been raised to an appropriate level for protecting the lumbar region PP, is not lowered by backflow of the inflation gas G to the upper inflation portion EU.

Thereafter, the check valve60continues to restrict flow of the inflation gas G from the lower inflation portion EL to the upper inflation portion EU (backflow), while permitting the inflation gas G to flow from the upper inflation portion EU to the lower inflation portion EL. Therefore, even if the airbag30restrains the lumbar region PP so that the internal pressure of the lower inflation portion EL is increased, the check valve60keeps restricting flow of the inflation gas G from the lower inflation portion EL to the upper inflation portion EU. Therefore, the internal pressure of the upper inflation portion EU is not increased by the influence of pressure changes of the lower inflation portion EL caused by restraint of the lumbar region PP.

Particularly, the inflation gas G flows between the upper inflation portion EU and the lower inflation portion EL only through the check valve60. That is, the inflation gas G does not flow between the upper inflation EU and the lower inflation portion EL without flowing through the check valve60. Thus, the check valve60is not impaired by the flow of the inflation gas G.

In a case where the internal pressure of the lower inflation portion EL reaches such a level that causes the rigid portions65contacting the wall joint portion63to move beyond the wall joint portion63, the parts of the valve body portions61,62below the flexible portions64follow the rigid portions65and act to move beyond the wall joint portion63to be inverted. This phenomena might open the closed flow passage between the valve body portions61,62and cause the inflation gas G in the lower inflation portion EL to flow back to the upper inflation portion EU through the check valve60. However, in the present embodiment, the lower end of the inflator assembly20is located in the vicinity of the outflow-side joint portions41,42in the upper inflation portion EU. Thus, the lower end of the inflator assembly20prevents the rigid portions65and the valve body portions61,62from moving toward the upper inflation portion EU by an excessive amount from the position of the closed state. As a result, the rigid portions65and the valve body portions61,62are prevented from moving beyond the wall joint portion63and from being inverted.

In the above, a typical operation of the side airbag apparatus has been described, the side airbag apparatus can operate in different manners. According to another mode, the check valve60operates in the same manner as described above partway. That is, the operation is the same up to the point where the flexible portions64are pulled toward the gas outflow inflation portions and the rigid portions65pulled toward the outflow-side joint portions41,42and toward the wall joint portion63.

After a such pulling action, parts of the valve body portions61,62below the flexible portions64are brought closer to each other by the high pressure of the inflation gas G flowing from the lower inflation portion EL to the upper inflation portion EU. The pressure receiving parts are collapsed toward the upper inflation portion EU, while being sequentially brought closely contact with the rigid portions65from sections closest to the rigid portions65. This reliably closes the flow passage of the inflation gas G between the valve body portions61,62.

The present embodiment described above has the following advantages.

(1) The upper ends of the valve body portions61,62are joined to the corresponding communication passage walls51,52by the outflow-side joint portions41,42, respectively. The flexible portions64are located between the outflow-side joint portions41,42and the lower inflation portion EL and in the vicinity of the outflow-side joint portions41,42. The front edges of the valve body portions61,62are joined to the corresponding communication passage walls51,52by the first edge joint portion67. The first edge joint portion67also functions as the wall joint portion63that joins the communication passage walls51,52to each other. The rear portions of the valve body portions61,62are joined together by a second edge joint portion68. The auxiliary joint portion69is located between the first edge joint portion67and the second edge joint portion68, and in the vicinity of the second edge joint portion68. The auxiliary joint portion69joins the valve body portions61,62to each other, and extends from the vicinity of the lower ends of the flexible portions64toward the lower inflation portion EL. The auxiliary joint portion69also functions as the rigid portions65, which extend along the gas flowing direction and are harder to flex than the flexible portions64.

With the above structure, when the inflation gas G is supplied to the check valve60, the pressure of the inflation gas G opens the upper and lower ends of the valve body portions61,62so that the inflation gas G can flow between the upper inflation portion EU and the lower inflation portion EL. When the supply of the inflation gas G is stopped, the difference in internal pressure between the inflation portions EL and EU causes the rigid portions65to fall toward the outflow-side joint portions41,42and the wall joint portion63about a fulcrum, which is the upper ends65U. This reduces the flow passage between the valve body portions61,62. Accordingly, the check valve60is closed, and the inflation gas G is prevented from flowing back from the lower inflation portion EL to the upper inflation portion EU. Thus, the check valve60is reliably opened and closed. With the above structure, the check valve60is opened and closed by the pressure of the inflation gas G. Therefore, no means for actuating the check valve60is required. This simplifies the structure of the check valve60.

(2) The length L2of the rigid portions65is longer than the distance D3between the distal end47T of the projection47and the ends C of the outflow-side joint portions41,42. Therefore, the rigid portions65and parts of the valve body portions61,62that are below the flexible portions64are prevented from moving beyond the wall joint portion63and from being inverted. The flow passage between the valve body portions61,62is reliably closed.

(3) The lower end of the inflator assembly20is located in the vicinity of the outflow-side joint portions41,42in the upper inflation portion EU. This arrangement of the inflator assembly20prevents the rigid portions65and the valve body portions61,62are prevented from moving beyond the wall joint portion63and from being inverted, even if the internal pressure of the lower inflation portion EL is excessively increased. The check valve60is therefore maintained closed.

(4) The rigid portions65are formed by sewing the valve body portions61,62with sewing threads. That is, by simply sewing the valve body portions61,62with sewing threads, the rigid portions65, which are harder to flex than the flexible portions64, are reliably formed.

(5) The airbag30is used in a side airbag apparatus, which is inflated and deployed forward in a space between the body side portion11and the occupant P seated on the vehicle seat12. The lower inflation portion EL, which is inflated in the vicinity of the lumbar region PP of the occupant P, is used as a gas inflow inflation portion, and the upper inflation portion EU, which is inflated in the vicinity of the thorax PT of the occupant P, is used a gas outflow inflation portion. In this case, even if the inflated airbag30restrains the lumbar region PP so that the internal pressure of the lower inflation portion EL is increased, the check valve60restricts flow of the inflation gas G from the lower inflation portion EL to the upper inflation portion EU. That is, the internal pressure of the upper inflation portion EU is prevented from being increased by pressure changes of the lower inflation portion EL caused by restraint of the lumbar region PP. Thus, the thorax PT, which has a low impact resistance, is softly protected by the upper inflation portion EU, while the lumbar region PP, which has a high impact resistance, is reliably restrained by the lower inflation portion EL.

Second Embodiment

A side airbag apparatus according to a first embodiment of the present invention will now be described with reference toFIGS. 17 to 21. 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.

FIG. 17shows the inner structure of an airbag module AM in a state where a seat back14is upright along a vertical direction.FIG. 17shows half of the airbag module AM that is located on the vehicle inner side. The airbag130includes a first inflation body131and a second inflation body132. Most of the first inflation body131is located above the second inflation body132.

(i) Configuration of Second Inflation Body132

As shown inFIGS. 17 and 18, the second inflation body132is formed by a fabric panel133, which is a single fabric sheet. A folding line134is formed in a center of the fabric panel133. The fabric panel133is folded into half at the folding line134so as to overlap onto itself. A part of the fabric panel133that is located on the vehicle inner side is referred to as a fabric portion135, and a part located on the vehicle outer side is referred to as a fabric portion136. The fabric portions135,136are symmetrically arranged with respect to the folding line134.

The peripheral portions of the fabric portions135,136except for upper portions are joined to each other by a peripheral joint portion137. The peripheral joint portion137is formed by sewing the fabric portions135,136with sewing threads. Portions of the fabric portions135,136that are not joined form a discharge port140for discharging the inflation gas G that has inflated the second inflation body132to the outside. The discharge port140is located between the peripheral joint portion137and a dividing joint portion161. The fabric portions135,136may be joined together such that the discharge port140is closed.

A part of the airbag130that is encompassed by the peripheral joint portion137is a lower inflation portion EL that is inflated and deployed by a relatively high internal pressure to restrain and protect the lumbar region PP of the occupant P. The lower inflation portion EL is located below a central inflation portion EC. A part of the airbag130without the peripheral joint portion137is an insertion portion138. An inflator accommodating portion139for accommodating the inflator assembly20is provided at a position forward of a folding line134of the insertion portion138. The fabric portions135,136are not sewn to each other at a front edge138F of the insertion portion138. The inflator accommodating portion139thus communicates with the insertion portion138.

(ii) Configuration of First Inflation Body31

As shown inFIGS. 17 and 19, the first inflation body131is formed by a fabric panel141, which is a single fabric sheet. A folding line141is formed in a center of the fabric panel142. The fabric panel141is folded into half at the folding line142so as to overlap onto itself. A part of the fabric panel141that is located on the vehicle inner side is referred to as a fabric portion143, and a part located on the vehicle outer side is referred to as a fabric portion144. The fabric portions143,144are symmetrically arranged with respect to the folding line142. The peripheral portions of the fabric portions143,144except for lower portions are connected to each other by a peripheral joining portion145. At a lower portion of the first inflation body131, a receptacle portion147is provided in front of the folding line142.

A tether151is provided in the first inflation body131. The tether151includes a pair of tether pieces152,153. The tether pieces152,153are each formed by a thin rectangular fabric sheet that extends in the front-rear direction. The front end of each of the tether pieces152,153reaches the front ends of the fabric portions143,144, and the rear ends of the tether pieces152,153extend to positions forward of the rear end of the fabric portions143,144. The lower edge of the tether piece152is joined to the fabric portion143on the vehicle inner side by a lower joint portion154. The lower edge of the tether piece153is joined to the fabric portion144on the vehicle outer side by a lower joint portion155. The front ends of the joint portions154,155reach the front end of the peripheral joint portion145, and the rear ends of the joint portions154,155reach a center region of the first inflation body131. The upper edges of the tether pieces152,153are joined together by an upper joint portion156. The lower joint portions154,155and the upper joint portion156are formed by sewing with sewing threads. The tether151extends between the fabric portions143,144of the first inflation body131. When the airbag130is not inflated, most parts of the tether pieces152,153overlap with each other.

The inner space of the first inflation body131is divided into an upper inflation portion EU and the central inflation portion EC by the tether151. The upper inflation portion EU is inflated and deployed by a relatively high internal pressure, and restrains and protects a shoulder PS of the occupant P. The central inflation portion EC is inflated and deployed by an internal pressure lower than that of the upper inflation portion EU, and restrains and protects the thorax PT of the occupant P. The central inflation portion EC is located below the upper inflation portion EU. The tether151restricts the thickness of the first inflation body131when inflated. Instead of the tether151, the inner space of the first inflation body131may be divided into the upper inflation portion EU and the central inflation portion EC by a seam. The seam is formed by sewing the fabric portions143,144after overlapping these on top of each other.

An annular closing portion157is provided in a portion of the first inflation body131that corresponds to an arm PA, more specifically, in a portion in the vicinity of the rear end of the tether151. The closing portion157allows an upper valve180provided in an upper opening OU to function as a check valve. The closing portion157is formed by annularly sewing the fabric portions143,144with sewing threads.

(iii) Combined Configuration of First and Second Inflation Bodies131,132

As shown inFIGS. 17 to 19, the insertion portion138of the second inflation body132is inserted into the receptacle portion147with the folding line134matched with the folding line142of the first inflation body131. The arrangement allows the receptacle portion147to wrap around of the insertion portion138.

A portion of the insertion portion138on the vehicle inner side is joined to a portion of the receptacle portion147on the vehicle inner side by the inner joint portion158. A portion of the insertion portion138on the vehicle outer side is joined to a portion of the receptacle portion147on the vehicle outer side by the inner joint portion159. The inner joint portions158,159do not connect the portions on the vehicle inner side and the portions on the vehicle outer side of the insertion portion138and the receptacle portion147to each other.

The insertion portion138and the receptacle portion147are joined to each other by the dividing joint portion161. If the insertion portion138is simply inserted into the receptacle portion147, the inner space of the first inflation body131and the inner space of the second inflation body132remain communicating with each other. In the present embodiment, the dividing joint portions161defines the inner space of the first inflation body131and the inner space of the second inflation body132. Further, the insertion portion138and the receptacle portion147are joined to each other by a part145A of the peripheral joint portion145.

The second inflation body132is a lower inflation portion EL that is inflated and deployed by a relatively high internal pressure to restrain and protect the lumbar region PP of the occupant P. The inflator assembly20is provided in the inflator accommodating portion139of the airbag130, while being inclined to be lower toward the front end. Most of the inflator assembly20is located in the central inflation portion EC. Two bolts26fixed to the retainer22are passed through rear portions of the fabric portions135,143on the vehicle inner side. A part in the vicinity of the peripheral joint portion145A of the airbag130is airtightly fastened to the upper end of the inflator assembly20by an annular fastening tool attached to the outside of the airbag130. In the second embodiment, an inner bag170, the upper valve180serving as a check valve, and a lower valve190are located in the airbag130.

The inner bag170mainly guides the inflation gas G from the inflator21to an upper portion, a front portion, and a lower portion in the airbag130, and inflates a rear portion of the central inflation portion EC of the airbag130by its own inflation. The inner bag170is arranged in the central inflation portion EC while satisfying the following condition (I). The condition (I) refers to a state in which, which the airbag130inflated and deployed and upright to be vertical, a front end170F of the inner bag170is located rearward of a front end ECF of the central inflation portion EC and forward of a front end14F of the seat back14. A front edge171of the inner bag170extends along the up-down direction at a center of the first inflation body131. The upper end of the front edge171is located forward of the closing portion157, and the lower end of the front edge171is located at the lower end of the central inflation portion EC (the first inflation body131). The rear end of the inner bag170is substantially located at the same spot as the rear end of the first inflation body131.

Unlike the first and second inflation bodies131,132, the inner bag170separately includes a fabric portion172located on the vehicle inner side and a fabric portion173located on the vehicle outer side. The fabric portion172is joined to the fabric portion143of the first inflation body131by an upper portion158U of the inner joint portion158, and is joined to the fabric portion143and the fabric portion135of the second inflation body132by a remaining portion158L of the inner joint portion158. The upper end of the fabric portion172is joined to the fabric portion143of the first inflation body131by another inner joint portion174. The front end of the inner joint portion174reaches the closing portion157, and the rear end of the inner joint portion174reaches the rear end of the fabric portion143.

Likewise, the fabric portion173is joined to the fabric portion144of the first inflation body131by an upper portion159U of the inner joint portion159, and is joined to the fabric portion144of the first inflation body131and the fabric portion136of the second inflation body132by a remaining portion159L of the inner joint portion159. The upper end of the fabric portion173is joined to the fabric portion144of the first inflation body131by another inner joint portion175. The front end of the inner joint portion175reaches the closing portion157, and the rear end of the inner joint portion175reaches the rear end of the fabric portion144.

The front edges of the fabric portions172,173are joined together by a joint portion176. A center opening OC is formed in a center of the fabric portions172,173, at which the joint portion176is not provided. The inner space of the inner bag170communicates with the central inflation portion EC through the center opening OC. The center opening OC faces forward.

The fabric portions172,173are joined to the tether151and the fabric portions143,144by the closing portion157. Also, the fabric portions172,173are joined to the fabric portions143,144of the first inflation body131and to the fabric portions135,136of the second inflation body132by the dividing joint portion161.

The upper end of the inner bag170is joined to the fabric portions143,144by the inner joint portions174,175in a space between the closing portion157and the rear end of the peripheral joint portion145. A part of the inner bag70to which the fabric portions172,173are not joined is referred to as the upper opening OU. The inner space of the inner bag170communicates with the upper inflation portion EU through the upper opening OU. The upper opening OU faces upward.

The lower end of the inner bag170is joined to the fabric portions135,136by the inner joint portions158,159in a space between the rear end of the dividing joint portion161and the folding line134. A part of the inner bag170to which the fabric portions172,173are not joined is referred to as a lower opening OL. The inner joint portions158,159intersect the peripheral joint portion145. The inner space of the inner bag170communicates with the lower inflation portion EL through the lower opening OL. The lower opening OL faces downward. If the flow passage areas of the center opening OC, the upper opening OU, and the lower opening OL are represented by SC, SU, and SL, respectively, the expressions SC<SU and SC<SL are satisfied. The flow passage areas SU and SL have similar sizes.

The upper valve180only permits the inflation gas G to flow from the inner bag170to the upper inflation portion EU. The upper valve180is located in the vicinity of the upper opening OU of the upper inflation portion EU. The upper valve180is located in the vicinity of the rear end of the airbag130.

The upper valve180separately includes a fabric portion181located on the vehicle inner side and a fabric portion182located on the vehicle outer side. The lower ends of the fabric portions181,182are arranged at the upper end of the inner bag170in the upper opening OU.

The fabric portions181,182are joined to the inner bag170and the airbag130by using parts of the inner joint portions174,175and a part of the closing portion157. The lower end of the fabric portion181, together with the fabric portion172of the inner bag170, is joined to the fabric portion143of the first inflation body131by the inner joint portion174. Also, the lower end of the fabric portion182, together with the fabric portion173of the inner bag170, is joined to the fabric portion144of the first inflation body131by the inner joint portion175. The inner joint portion174is formed by sewing the fabric portions181,172of the upper valve180and the inner bag170to the fabric portion143of the first inflation body131. The inner joint portion175is formed by sewing the fabric portions182,173of the upper valve180and the inner bag170to the fabric portion144of the first inflation body131. The lower end of the fabric portion181and the lower end of the fabric portion182are not joined to each other.

The front ends of the fabric portions181,182, together with the fabric portions172,173of the inner bag170and the tether pieces152,153of the tether151, are joined to the fabric portions143,144of the first inflation body131by the closing portion157. The closing portion157is formed by sewing the first inflation body131, the tether151, the inner bag170, and the upper valve180together.

As shown inFIGS. 17 and 20, a joint portion183extending in the up-down direction is provided at the fabric portions181,182. The fabric portions181,182are joined to each other by the joint portion183. A lower end183L of the joint portion183reaches the upper ends of the fabric portions172,173of the inner bag170. The lower ends of the rear portions of the fabric portions181,182are joined to the inner bag170. The joint portion183is formed by sewing the rear ends of the fabric portions181,182together at a portion of the upper valve180that is outside of the inner bag170. The joint portion183is formed by sewing the upper valve180and the inner bag170together at a portion of the upper valve180that is inside of the inner bag170.

The fabric portions181,182each have an inclined portion184, which is inclined to be lower toward the front end. The fabric portions181,182are not joined together at parts corresponding to the inclined portions184. The lower ends of the fabric portions181,182are joined to the fabric portions172,173,143, and144. However, the fabric portions181,182are not joined to each other. Therefore, the upper valve180has a cylindrical shape opened at the inclined portions184and the lower end.

Since the fabric portion181is joined to the fabric portion143of the first inflation body131by the inner joint portion174, the inflation gas G cannot flow between the upper inflation portion EU and the central inflation portion EC through between the fabric portions181,143. Likewise, since the fabric portion182is joined to the fabric portion144of the first inflation body131by the inner joint portion175, the inflation gas G cannot flow between the upper inflation portion EU and the central inflation portion EC through between the fabric portions182,144. The inflation gas G can flow between the upper inflation portion EU and the central inflation portion EC by flowing through only the upper valve180. The lower ends of the fabric portions181,182are located rearward of the tether151and faces the central inflation portion EC. The inclined portions184of the fabric portions181,182are located at a lower part in the upper inflation portion EU, and rearward of the tether151.

The lower ends and the front ends of the fabric portions181,182are joined to the fabric portions143,144of the first inflation body131. The fabric portions181,182are not joined to the fabric portions143,144at the remaining portions. Thus, the upper portion of the upper valve180is easier to flex than other parts. Thus, when the internal pressure of the central inflation portion EC is higher than the internal pressure of the upper inflation portion EU, the upper portion of the upper valve180extends upward so that the upper opening OU is opened. In contrast, when the internal pressure of the central inflation portion EC is lower than the internal pressure of the upper inflation portion EU, the upper opening OU (a bendable portion188) is closed.

The lower valve190only permits the inflation gas G to flow from the inner bag170to the lower inflation portion EL. The lower valve190is located in the vicinity of the lower opening OL of the lower inflation portion EL. The lower valve190is located in the vicinity of the rear end of the airbag130. The lower valve190basically has the same structure as the upper valve180. The lower valve190separately includes a fabric portion191located on the vehicle inner side and a fabric portion192located on the vehicle outer side. The upper ends of the fabric portions191,192are arranged in the inner bag170at the lower opening OL.

The fabric portions191,192are joined to the inner bag170and the airbag130by using parts of the inner joint portions158,159and a part of the dividing joint portion161. The upper end of the fabric portion191, together with the fabric portion172of the inner bag170, is joined to the fabric portions143,135of the first inflation body131and the second inflation body132by the inner joint portion158. Also, the upper end of the fabric portion192, together with the fabric portion173of the inner bag170, is joined to the fabric portions144,136of the first inflation body131and the second inflation body132by the inner joint portion159. In this case, the inner joint portion158is formed by sewing the fabric portions191,172of the lower valve190and the inner bag170to the fabric portions143,135of the first and second inflation bodies131,132. The inner joint portion159is formed by sewing the fabric portions192,173of the lower valve190and the inner bag170to the fabric portions144,136of the first and second inflation bodies131,132. The upper end of the fabric portion191and the upper end of the fabric portion192are not joined to each other.

The front ends of the fabric portions191,192, together with the inner bag170, are joined to the first and second inflation bodies131,132by the dividing joint portion161. The dividing joint portion161is formed by sewing the first inflation body131, the second inflation body132, the inner bag170, and the lower valve190together.

As shown inFIGS. 17 and 21, a joint portion193extending in the up-down direction is provided at the fabric portions191,192. The fabric portions191,192are joined to each other by the joint portion193. An upper end193U of the joint portion193reaches the lower end of the inner bag170. The upper ends of the rear portions of the fabric portions191,192are joined also to the inner bag170. The joint portion193is formed by sewing the rear ends of the fabric portions191,192together at a portion of the lower valve190that is outside of the inner bag170. The joint portion193is formed by sewing the lower valve190and the inner bag170together at a portion of the lower valve190that is inside of the inner bag170.

The fabric portions191,192each have an inclined portion194, which is inclined to be higher toward the front end. The fabric portions191,192are not joined to each other. The upper ends of the fabric portions191,192are joined to the fabric portions172,173,143,144,135, and136. However, the fabric portions191,192are not joined to each other. Therefore, the lower valve190has a cylindrical shape opened at the inclined portions194and the upper end.

Since the fabric portion191is joined to the fabric portion135of the second inflation body132by the inner joint portion158, the inflation gas G cannot flow between the lower inflation portion EL and the central inflation portion EC through between the fabric portions191,135. Likewise, since the fabric portion192is joined to the fabric portion136of the second inflation body132by the inner joint portion159, the inflation gas G cannot flow between the lower inflation portion EL and the central inflation portion EC through between the fabric portions192,136. The inflation gas G can flow between the lower inflation portion EL and the central inflation portion EC by flowing through only the lower valve190.

The upper ends of the fabric portions191,192are located rearward of the dividing joint portion161and faces the central inflation portion EC. The inclined portions194of the fabric portions191,192are located at an upper part in the lower inflation portion EL, and rearward of the dividing joint portion161. The lower end of the retainer22is tucked into the lower valve190.

The upper ends and the front ends of the fabric portions191,192are joined to the fabric portions135,136. The fabric portions191,192are not joined to the fabric portions135,136at the remaining portions. Thus, the lower portion of the lower valve190is easier to flex than other parts. Thus, when the internal pressure of the central inflation portion EC is higher than the internal pressure of the lower inflation portion EL, the lower portion of the lower valve190extends downward so that the lower opening OL is opened. In contrast, when the internal pressure of the central inflation portion EC is lower than the internal pressure of the lower inflation portion EL, the lower opening OL (a bendable portion198) is closed.

The present invention may be embodied in the following forms.

In the first embodiment, the retainer22, which has a closed upper end and open lower end, may be replaced by a retainer of which the upper and lower ends are both open. Further, without using the retainer22, the inflator21may be directly attached to the seat back14. Alternatively, the retainer22may be replaced by an inner tube made by making a fabric sheet into a cylinder. This modification is made on the premise that the heat and pressure of the inflation gas G from the inflator21do not significantly damage the inner tube. Also, this modification is also possible in the case where an inflator that ejects inflation gas G having a relatively low temperature is used. Such inflators include a hybrid type inflator filled with inflation gas. This type of inflator is capable of ejecting inflation gas G at a lower temperature than a pyro type inflator using a gas generating agent to generate inflation gas through chemical reaction accompanied by heat. This modification can be made even in a case where a pyro type inflator is used, if the inner tube is formed by a sheet coated with a coating layer for improving the heat resistance.

In the first embodiment, the present invention may be applied to an airbag apparatus having three or more inflation portions. In this case, the check valve60is located in each communication passage between two adjacent inflation portions. In a case where an airbag has three or more inflation portions, the airbag includes a plurality of combinations of adjacent inflation portions. Accordingly, the airbag has a plurality of communication passages. In this case, the check valve60is provided in at least one of the communication passages. In a case where the airbag30has a plurality of inflation portions, which of the inflation portions is used as a gas inflow inflation portion and which of the inflation portions is used as a gas outflow inflation portion are determined in accordance with the impact resistance of each body part of the occupant P.

In the first embodiment, the rigidness and the length L2of the rigid portions65may be changed to adjust the internal pressure of the inner inflation portion EL when the rigid portions65move beyond the wall joint portion63or when the valve body portions61,62are inverted. For example, when sewing the rigid portions65, the rigidness of the rigid portions65may be adjusted by changing the type, size, and number of sewing threads. For example, if the size and number are increased, the rigid portions65are more rigid, so that the internal pressure of the lower inflation portion EL when the valve body portions61,62are inverted is increased. In the case where the rigid portions65are formed by adhesion, the rigidness of the rigid portions65can be adjusted by changing the type and applied amount of adhesive. For example, if the applied amount is increased, the rigid portions65are more rigid, so that the internal pressure of the lower inflation portion EL when the valve body portions61,62are inverted is increased.

As shown inFIGS. 22 and 23, the first edge joint portion67and the wall joint portion63may be located at different positions in the airbag30. The first edge joint portion67may be modified as long as it joins the front edges of the valve body portions61,62to the corresponding communication passage walls51,52. In the example shown inFIG. 23, the first edge joint portion67joins the first valve body portion61only to the first communication passage wall51and joins the second valve body portion62only to the second communication passage wall52. The wall joint portion63may be modified as long as it joins the communication passage walls51,52to each other. In the example shown inFIG. 23, the wall joint portion63only joins the communication passage walls51,52to each other. Even if the first edge joint portion67and the wall joint portions63are located at different positions as described above, the same advantages as the first embodiment are achieved.

As shown inFIGS. 24 and 25, the rigid portions65and the auxiliary joint portion69may be located at different positions in the valve body portions61,62. The auxiliary joint portion69may be modified as long as it is located in the vicinity of the second edge joint portion68, and joins the valve body portions61,62to each other, and extends from the vicinity of the lower ends of the flexible portions64toward the lower inflation portion EL. The rigid portions65may be modified as long as they are provided on or in the vicinity of the auxiliary joint portion69, extend along the gas flowing direction, and are harder to flex than the flexible portions64. Even if the rigid portions65and the auxiliary joint portion69are located at different positions as described above, the same advantages as the first embodiment are achieved.

As shown inFIGS. 24 and 25, the check valve60may be formed by overlapping a pair of fabric sheets. In this case, the fabric sheet located on the vehicle inner side is referred to as a first valve body portion61, and the fabric sheet located on the vehicle outer side is referred to as a second valve body62. The valve body portions61,62are joined together to form a cylindrical check valve60. The rear portions of the valve body portions61,62are joined together by a second edge joint portion68. The first embodiment is different from this modification in that the single fabric sheet58is folded in half, and the folded part is referred to as the second edge joint portion68. The rigid portions65may be formed by a material other than sewing threads on condition that the rigid portions65extend along the gas flowing direction and are harder to flex than the flexible portions64, and are located on or in the vicinity of the auxiliary joint portion69of the check valve60. For example, elongated plates made of synthetic resin or metal may be used as rigid portions65.

As shown inFIG. 26, the rigid portions65may extend in a direction that intersects the second edge joint portion68(the folding line59). This allows the flow passage area DS between the valve body portions61,62to be adjusted, so that the flow rate of the inflation gas G is adjusted. For example, as the angle of intersection increases, the distance between the rigid portions65and the first edge joint portion67is reduced, and the flow passage area DS is reduced. This reduces the flow rate of the inflation gas G that flows into the lower inflation portion EL.

In an airbag apparatus having a tether for dividing the interior of the airbag into a plurality of inflation portions, a check valve may be provided in the tether as shown inFIGS. 27 and 28. The tether80includes a pair of tether pieces81,82. One edge (left edge as viewed inFIG. 28) of the tether piece81is joined to the fabric portion33of the airbag30by an edge joint portion83. Another edge (right edge as viewed inFIG. 28) of the tether piece82is joined to the fabric portion34of the airbag30by an edge joint portion83. Further, the other edges of the tether pieces81,82are joined to each other by an edge joint portion84. In this manner, the tether80is extends between the fabric portion33and the fabric portion34of the airbag30. The tether80is bent upward when the airbag30is not inflated. The edge joint portions83,84may be formed by adhesion using adhesive, instead of sewing threads. This modification may be applied to the outflow-side joint portions93,94, a first edge joint portion96, a wall joint portion97, an auxiliary joint portion103, and the rigid portions102.

The interior of the airbag30is divided into a lower inflation portion and an upper inflation portion by the tether80serving as the boundary. In this modification, the former is used as a gas outflow inflation portion85, and the latter is used as a gas inflow inflation portion86. The gas outflow inflation portion85is inflated by a relatively low internal pressure and protects the thorax PT, which has a relatively low impact resistance, and the gas inflow inflation portion86is inflated by an internal pressure higher than that of the gas outflow inflation portion85, and protects a shoulder PS, which has a higher impact resistance than the thorax PT. Besides dividing the airbag30into the two inflation portions85,86, the tether80restricts the thickness of the airbag30when it is inflated.

A communication passage87is provided in a part of the edge joint portion84. The communication passage87connects the gas outflow inflation portion85and the gas inflow inflation portion86to each other. The communication passage87is provided between the tether pieces81,82and at a portion where the tether pieces81,82are not joined together by the edge joint portion84. A part of the tether piece81forms a first communication passage wall88of the communication passage87, while a part of the tether piece82forms a second communication passage wall89of the communication passage87. The first and second communication passage walls88,89are flat and laid on top of each other when the inflation portions85,86are not inflated.

A check valve90is formed by folding a single fabric sheet100in half along a folding line101. The check valve90includes a first valve body portion91located on the vehicle inner side and a second valve body portion92located on the vehicle outer side. The valve body portions91,92are laid on top of each other in a flat state when the inflation portions85,86are not inflated.

The lower end of the first valve body portion91is joined to the first communication passage wall88by the first outflow-side joint portion93. The lower end of the second valve body portion92is joined to the second communication passage wall89by the second outflow-side joint portion94. The lower ends of the valve body portions91,92are not joined to each other.

The front edges of the valve body portions91,92are joined to the corresponding communication passage walls88,89by the first edge joint portion96. In this modification, the front edges of the valve body portions91,92are joined to each other by the first edge joint portion96. Further; the lower ends f the front edges of the valve body portions91,92are joined to the communication passage walls88,89. That is, at the front lower ends of the valve body portions91,92, the valve body portions91,92and the communication passage walls88,89are joined to each other. The lower end of the first edge joint portion96is formed by sewing the front edges of the valve body portions91,92and the communication passage walls88,89together. The first edge joint portion96extends from the upper end of the valve body portions91,92toward the gas outflow inflation portion85. The lower end of the first edge joint portion96intersects the edge joint portion84and the outflow-side joint portions93,94. A lower part of the first edge joint portion96also serves as the wall joint portion97. The wall joint portion97is located on or in the vicinity of the first edge joint portion96, and joins the communication passage walls88,89to each other.

As indicated by an alternate long and short dash line inFIG. 27, the valve body portions91,92each have a flexible portion98. The flexible portion98is easily flexed toward the gas outflow inflation portion85(downward as viewed inFIG. 27) by the pressure of the inflation gas G. The flexible portion98is located between the outflow-side joint portions93,94and the gas inflow inflation portion86and in the vicinity of the outflow-side joint portions93,94.

The rear portions of the valve body portions91,92are joined together by a second edge joint portion99. In this modification, the single fabric sheet100is folded in half along the folding line101, so as to form the first and second valve body portions91,92. Accordingly, the folded back portion, that is, a part including the folding line101corresponds to a second edge joint portion99.

Further, rigid portions102are provided in the rear parts of the valve body portions91,92, that is, a part of the fabric sheet100that is forward of the folding line101. The rigid portions102extend toward the gas inflow inflation portion86from positions in the vicinity of the upper ends of the flexible portions98, that is, from a position that is separated upward from the outflow-side joint portions93,94by a predetermined distance. The rigid portions102are formed by sewing the valve body portions91,92with sewing threads in a single or multiple rows. The rigid portions102are more rigid and harder to flex than the flexible portions98and other parts of the check valve90.

The rigid portions102also function as the auxiliary joint portion103. The auxiliary joint portion103is located between the first edge joint portion96and the second edge joint portion99, and in the vicinity of the second edge joint portion99. The auxiliary joint portion103joins the valve body portions91,92to each other. The auxiliary joint portion103extends toward the gas inflow inflation portion86from the vicinity of the upper end of the flexible portions98, that is, from a position separated upward from the outflow-side joint portions93,94by a predetermined distance. This modification has the same advantages as the first embodiment.

In the first embodiment, the inclined portions66of the valve body portions61,62may be omitted. Also, the outflow-side joint portion41,42,93,94do not need to be substantially perpendicular to the flowing direction of the inflation gas G in the communication passages50,87, as long as they intersect the flowing direction.

If the internal pressures of the upper and lower inflation portions EU, EL are set to be different such that the internal pressure of the upper inflation portion EU is lower than that of the lower inflation portion EL, the check valves60,90easily operate. Means for generating a difference in internal pressure includes vent holes formed in the upper inflation portion EU or both in the upper and lower inflation portions EU, EL. In this case, the size of each vent hole needs to be adjusted such that the amount of inflation gas G discharged from the lower inflation portion EL86is smaller than the upper inflation portion EU85.

The storage portion15may be provided in the body side portion11, instead of in the seat back14. The present invention may be applied to an airbag apparatus of a type different from the above described side airbag apparatus.