Side airbag system

Abstract

Side airbag device comprising a gas generator (30) for ejecting an inflation gas in response to a shock exerted from a lateral direction of a vehicle (10) and an airbag (40) which is housed in a folded state and is unfolded and inflated by the inflation gas from the gas generator (30) between an occupant (P) seated in a vehicle seat (12) and a side wall (11) of the vehicle (10) in an area extending from a chest area (PT) to the head (PH) of the occupant (P), wherein the airbag (40) is divided by a subdivision (50) extending in a substantially vertical direction into a front inflation chamber (47) and a rear inflation chamber (46), the gas generator (30) being arranged on a lower section of the rear inflation chamber (46),the subdivision (50) is provided with an upper communication hole (54) for communication between the rear filling chamber (46) and the front filling chamber (47) on a section that is one side of the head (PH) of the occupant (P), the subdivision (50) is provided with a lower communication hole (55) for communication between the rear filling chamber (46) and the front filling chamber (47) on a section that is one side of the chest area (PT) of the occupant (P), and an opening area of ​​the lower communication hole (55) is arranged to be larger than that of the upper communication hole (54).

Description

The present invention relates to a side airbag device that inflates and deploys an airbag in a space between an occupant seated in a vehicle seat and a side wall of the vehicle when an impact is applied to the vehicle from a lateral direction due to a side collision or the like, thereby protecting a region extending from a chest region to the head of the occupant from the impact.A side airbag device including an airbag and a inflator is widely known as a device capable of protecting an upper body of an occupant seated in a vehicle seat from an impact caused by a side collision or the like. The airbag and the inflator of the side airbag device are accommodated in a seat back (seat back) of the vehicle seat, the airbag being folded. When an impact is applied to a side wall, for example, a side door, of the vehicle from a lateral direction due to the side collision or the like, inflation gas is supplied from the inflator to the airbag. The airbag is deployed and inflated to jump out of the vehicle seat in a state where a portion of the airbag remains in the seat back. Thereafter, the airbag is deployed and inflated in a narrow space between the upper body of the occupant and the side wall of the vehicle. The airbag is interposed between the occupant and the side wall moving toward an inner side of a vehicle compartment to restrain the upper body of the occupant while absorbing the impact applied to the upper body via the side wall.An aspect of such a side airbag device is disclosed in, for example, JP 2000-280 853 A (see FIGS. 9A, 9B, 10A, and 10B ), wherein an airbag is deployed and inflated in an approximately vertical elongated shape between the region extending from the chest region toward the head of the occupant and the side wall of the vehicle. The airbag of the side airbag device is divided into a front inflation chamber and a rear inflation chamber by a partition inclined downward toward the front side thereof, and a gas generator is disposed at a lower portion of the rear inflation chamber. The partition is provided with a plurality of fine holes for communicating the rear inflation chamber with the front inflation chamber. The number of these fine holes is increased toward a rear portion of the partition, that is, these fine holes are provided in a low density front portion but are provided in a high density rear portion. The airbag is accommodated together with the inflator in the seat back adjacent to one side of the chest portion, the airbag being folded.According to the side airbag device, when the inflation gas is ejected from the inflator in response to the impact caused by the side collision or the like, the inflation gas is supplied upward into the rear inflation chamber to deploy and fill the rear inflation chamber in an approximately upward direction. Also, a part of the inflation gas is supplied into the front inflation chamber through the fine holes to deploy and inflate the front inflation chamber while being supplied approximately upward into the rear inflation chamber.DE 10 2009 014 302 A1 discloses a side airbag device for a vehicle having an airbag bag and a gas generator arranged in the lower region thereof for filling the airbag bag, wherein the airbag bag is divided into a first, rear chamber and a second, front chamber by an approximately vertically extending separating seam. However, the two chambers which thereby extend substantially vertically are only connected to one another in the upper end region (head region) of the side airbag bag by a single gas transfer passage, so that the rear chamber can be inflated in front of the front chamber and the front chamber can subsequently be inflated from top to bottom.DE 10 2009 014 302 A1 discloses a side airbag device in which a first, inner airbag bag, which extends substantially over the entire length of the airbag in the vertical direction and communicates with a gas generator, and a second, outer airbag bag, which is divided by corresponding seams into three mutually separated chambers for pelvis, chest and shoulder / head, are formed. Gas exchange between these individual sub-chambers of the outer airbag bag is not provided, because the individual chambers are each connected via openings only to the inner airbag bag.DE 603 19 427 T2 discloses a vehicle seat with an integrated airbag unit. The vehicle seat includes a seat cushion, a seat back including a frame, and an airbag unit including an inflatable airbag and an inflator. The airbag unit is mounted on the frame of the seat back such that the inflator is located at the rearmost portion of the frame. This arrangement causes a substantial length of the airbag to press against the frame upon inflation and thus position itself between the frame and an occupant.EP 2 412 585 A1 discloses an airbag device. An inflating portion of an airbag is divided into an upstream and a downstream inflating portion by a partition member. A pressure regulating valve, which is closed at an early stage of gas supply and opened from the middle of the supply period, controls the gas flow between the sections. The valve includes a slit-like inner opening in the partition member and a pair of valve body portions. The separating element is designed such that it is longer in the longitudinal direction than in the transverse direction in the tensioned state.With respect to the upper body of the occupant, a shoulder mainly protrudes in a lateral direction, and therefore comes closest to the side wall of the vehicle. The clearance between the upper body of the occupant and the side wall is at a minimum at a position adjacent to the shoulder before the impact is applied to the vehicle from the lateral direction.Meanwhile, as described above, the airbag is accommodated in the seat back adjacent to the chest portion side before being deployed and inflated. For this reason, in order to deploy and fill the airbag on the side of the head, it is necessary for the airbag to pass through the narrow space between the shoulder and the side wall that is higher than the chest portion.The side airbag device disclosed in JP 2000-280 853 A does not perform any particular examination of how the airbag passes through the narrow space between the shoulder and the side wall as described above. For this reason, a portion of the airbag deployed and inflated on the side of the head of the occupant is deployed and inflated early with respect to other portions, so that when the portion is deployed and inflated before passing the side of the shoulder, the passage of the portion through the narrow space hardly occurs, possibly interrupting the inflation and deployment of other portions of the airbag. In particular, in JP 2000-280 853 A, since the fine holes are provided in low density in the front portion and are provided in high density in the rear portion, the inflation gas is easily supplied to the portion of the airbag on the side of the head of the occupant being deployed and inflated, and therefore the above-described problem may easily occur.The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a side airbag device that can properly deploy and fill an airbag on a side of a region extending from a chest region to a head of an occupant.In order to solve the above-mentioned problems, a side airbag device according to claim 1 is provided.With the above configuration, since a part of the inflation gas supplied from the inflator flows upward in the rear inflation chamber of the airbag, the rear inflation chamber is deployed and inflated. When the inflation gas arrives at the occupant's chest region side, a part of the inflation gas flows into the lower portion of the front inflation chamber through the lower communication hole. Also, the inflation gas that does not pass through the lower communication hole but flows upward opposite to the lower communication hole arrives at the side of the head of the occupant, and a part of the inflation gas flows into the upper portion of the front inflation chamber through the upper communication hole. In this case, since the opening area of the lower communication hole is set to be equal to or larger than that of the upper communication hole, the inflation gas flows through the lower communication hole in an amount equal to or larger than that of the upper communication hole.The lower portion of the front inflation chamber is deployed and inflated by the inflation gas passing through the lower communication hole on the front portion side of the chest region of the occupant. Also, the upper portion of the front inflation chamber is deployed and inflated by the inflation gas passing through the upper communication hole on the side of the front portion of the head of the occupant. As described above, since the flow rate of the inflation gas at the lower communication hole and the upper communication hole is different, the portion to be deployed and inflated at the front portion side of the head is not deployed and inflated earlier than other portions, particularly the front portion side of the chest region, but is deployed and inflated after passing through the narrow clearance portion between the shoulder and the side wall.In the side airbag device, the front inflation chamber is preferably provided with a vent hole for exhausting the inflation gas between the upper communication hole and the lower communication hole.With the configuration described above, when the inflation gas flowing through the upper communication hole to the upper portion of the front inflation chamber is about to flow upward, a part of the inflation gas is discharged to the outside of the airbag from the vent hole provided between the upper communication hole and the lower communication hole. For this reason, the inflation gas flows to the lower portion of the front inflation chamber, thereby preventing the lower portion from being deployed and inflated with the excessive pressure on the chest region side.The side airbag device preferably includes a thickness decreasing portion that is provided at a portion of the airbag that is located at a shoulder side of the occupant and that decreases a inflation thickness in a lateral direction of the vehicle from that of other portions during inflation.With the configuration described above, the inflation thickness of the airbag portion, which is the shoulder side of the occupant, in the lateral direction of the vehicle by the thickness decreasing portion is smaller than that of other portions. For this reason, the airbag portion, which is the side of the occupant's shoulder, is easily deployed and inflated also at the portion of the narrow space between the shoulder and the side wall of the vehicle.In the side airbag device, preferably, when the airbag is fully deployed and inflated, a front end of a portion of the airbag positioned on the side of the head of the occupant is positioned closer to a front side of the vehicle than a front end of a portion of the airbag positioned on the side of the chest region of the occupant.With the above-described configuration, the airbag area deployed and inflated on the side of the head is widened forward, thereby improving its ability to retain and protect the head from the shock.In the side airbag device, the airbag is preferably provided with folded portions formed by folding the airbag from top to bottom, and the upper communication hole of the partition is positioned at the uppermost folded portion.In the airbag including the plurality of folded portions formed by folding the airbag from top to bottom, a part of the inflation gas ejected from the inflator flows from the folded portion closest to the inflator to the uppermost folded portion farthest from the inflator, so that the rear inflation chamber is deployed and inflated. Here, when the upper communication hole of the partition is positioned at a folded portion lower than the uppermost folded portion, the inflation gas flows through the upper communication hole to the front portion of the folded portion to deploy and inflate the front portion, which may cut the deployment and inflation of the uppermost folded portion.In view of this, since the upper communication hole of the partition is positioned in the uppermost folded portion of the airbag, the airbag is deployed in the order from the lower folded portion to the upper folded portion. In the process in which the uppermost folded portion is deployed, the inflation gas in the rear inflation chamber flows through the upper communication hole to the front inflation chamber, and therefore it is possible to prevent the deployment and inflation of the uppermost folded portion from being interrupted due to the upper communication hole.According to the side airbag device, since the opening area of the lower communication hole is configured to be equal to or larger than that of the upper communication hole in the division, the airbag can be properly deployed and inflated on the side of the region extending from the chest region to the head of the occupant. FIG. 1 is a side view illustrating an occupant and a vehicle seat provided with a side airbag device according to an embodiment of the present invention; FIG. 2 is a plan view in section illustrating a positional relationship among the vehicle seat, the airbag, the occupant, and a side wall of the vehicle according to the embodiment; FIG. 3 is a front sectional view illustrating a positional relationship among the vehicle seat, the airbag, the occupant, and the side wall of the vehicle according to the embodiment; FIG. 4 is a partial plan view in section illustrating an internal structure of a side portion of a seat back in which an airbag module is accommodated according to the embodiment; FIG. 5 is a side view illustrating the airbag module in a state where the airbag is deployed but not yet inflated according to the embodiment; FIG. 6 is a plan view in section schematically illustrating the internal configuration of the airbag according to the embodiment; FIG. 7 is a partial side elevational view in section illustrating the internal structure of the airbag module in FIG. 5 together with the occupant and the vehicle seat; FIG. 8 is a side view illustrating the state before the airbag of the airbag module according to the embodiment is not folded; FIGS. 9A and 9B are diagrams illustrating a state of folding the airbag in the airbag module according to the embodiment, wherein FIG. 9A is a side view and FIG. 9B is a rear view when viewed from a left side of FIG. 9A ; FIGS. 10A and 10B are diagrams illustrating a state of folding the airbag in the airbag module according to the embodiment, wherein FIG. 10A is a side view and FIG. 10B is a rear view when viewed from a left side of FIG. 10 ; FIGS. 11A and 11B are diagrams illustrating a state of folding the airbag in the airbag module according to the embodiment, wherein FIG. 11A is a side view and FIG. 11B is a rear view when viewed from a left side of FIG. 11A ; FIGS. 12A and 12B are diagrams illustrating a state of folding the airbag in the airbag module according to the embodiment, in which FIG. 12A is a side view as viewed from a rear side of FIG. 11A and FIG. 12B is a rear view as viewed from a right side of FIG. 12A ; FIGS. 13A and 13B are diagrams illustrating a state of folding the airbag in the airbag module according to the embodiment, in which FIG. 13A is a side view and FIG. 13B is a sectional view taken along line A-A in FIG. 13A ; FIGS. 14A and 14B are diagrams illustrating a state of folding the airbag in the airbag module according to the embodiment, wherein FIG. 14A is a side view and FIG. 14B is a sectional view taken along the line B-B in FIG. 14A ; FIGS. 15A and 15B are diagrams illustrating the folded airbag accommodated in the airbag module according to the embodiment, in which FIG. 15A is a side view and FIG. 15B is a sectional view taken along line C-C in FIG. 15A ; FIG. 16 is a partial plan view in section illustrating a state in which the airbag is deployed and inflated after jumped out of the vehicle seat, leaving a part of the airbag in the seat back; FIG. 17 is a side view illustrating a positional relationship between a fold line and a folded portion in the airbag according to the embodiment; and FIG. 18 is a partial side view illustrating an occupant and a vehicle seat provided with an airbag according to a modification.Description of the Reference Numerals10 Vehicle 11 Side wall 12 Vehicle seat 31 Inflator 40 Airbag 40 a, 40 bFront end 46 Rear inflation chamber 47 Front inflation chamber 50 Partition 54 Upper communication hole 55 Lower communication hole 56 Exhaust hole 66, 68, 69, 72, 73 Folded portion 86 Connection portion (thickness reduction portion) 87 Concave portion P Occupant PH Head PS Shoulder PT Chest regionNext, a side airbag device according to an embodiment will be described with reference to FIGS. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 to 17.Hereinafter, the direction in which a vehicle advances will be referred to as a forward direction, and the terms front, rear, upper (upward), lower (downward), left and right will be defined with reference to the forward direction. Also, in each drawing, front indicates a front side of the vehicle, rear indicates a rear side of the vehicle, inside indicates an inner side of the vehicle, and outside indicates an outer side of the vehicle. The inner side of the vehicle is a side that is close to the central axis of the lateral direction of the vehicle with respect to the lateral direction of the vehicle, and the outer side of the vehicle is a side that is spaced apart from the central axis.Also, it is assumed that an occupant (adult) having a standard body structure is seated in a vehicle seat in a predetermined posture (normal posture).As illustrated in FIGS. 1, 2 to 3, a vehicle seat 12 is located in the vicinity of the vehicle inner side of a side wall 11 in a vehicle 10. For example, the side wall 11 corresponding to a front seat includes a front door and a center pillar (B pillar). Also, the side wall 11 corresponding to a rear seat includes a rear portion of a side door (back door), a C-pillar, a front portion of a wheel house, and a rear quarter panel ("rear quarter panel").The vehicle seat 12 includes a seat cushion (seat part) 13 and a seat back (backrest) 14 that extends upward from a rear side of the seat cushion 13, and an inclination angle of the seat back 14 is adjusted by a reclining mechanism (not shown). The vehicle seat 12 is disposed in the vehicle 10 with the seat back 14 facing forward. The lateral direction of the vehicle seat 12 arranged in this manner coincides with the lateral direction of the vehicle.The seat back 14 includes a seat back body 15 and a pair of side support portions 16 provided on both sides of the seat back body 15 in the lateral direction of the seat back body 15. The seat back body 15 is inclined rearward to support a torso of an occupant P from behind. Both side support portions 16 project from the seat back body 15 to restrain movement of the upper body of the occupant seated on the seat cushion 13 and inclined against the seat back body 15 from movement in the lateral direction of the vehicle.Next, the internal structure of the seat back 14, specifically, the vehicle exterior side portion including the vehicle exterior side support portion 16 will be described.A seat frame forming a framework of the seat back 14 is installed in the seat back. A portion of the seat frame is located on the vehicle exterior of an inner space of the seat back 14 as illustrated in FIG. 4. The portion of the seat frame is referred to as a side frame portion 17 and is formed by bending a metal sheet. A seat pad 18 made of an elastic material such as urethane foam is disposed in front of the seat frame including the side frame portion 17. A back plate 19 made of a hard material such as a synthetic resin is provided behind the seat frame. Although the seat pad 18 is padded by padding, the padding is not shown in FIG. 4. The same applies to FIG. 16 described below.An accommodation portion 21 is provided in the seat pad 18 at a position adjacent to the vehicle exterior side of the side frame portion 17. The position of the accommodation portion 21 is a central portion of the seat back 14 in the up / down direction, and is located obliquely rearward of the occupant P seated in the vehicle seat 12 (see FIG. 2 ). An airbag module AM constituting a main part of the side airbag device is accommodated in the accommodation portion 21.A slit 22 extends diagonally forward and outward from the vehicle outer side and the front corner of the accommodation portion 21. A portion of the seat pad 18 located between a front corner 18C of the seat pad 18 and the gap 22 (i.e., a portion surrounded by a dashed / two-dot line in FIG. 4 ) forms a breakable portion 23 to be broken by the airbag 40, which will be described below.The airbag module AM installed in the seat back 14 includes a inflator assembly 30 and the airbag 40 as its main components. Next, each of the components will be described.Inflator Assembly 30The inflator assembly 30 includes an inflator 31 serving as a gas generation source and a container or receptacle 32 covering the inflator 31. In this embodiment, a pyrotechnic gas generator is used as the gas generator 31. The inflator 31 is formed in a generally cylindrical shape and contains therein a gas generating agent (not shown) for generating a inflation gas.In place of the pyrotechnic gas generator using the gas generating agent, it is possible to use a hybrid type gas generator that breaks a division of a high-pressure gas cylinder filled with a high-pressure gas by an explosive to expel gas.On the other hand, the container 32 functions as a diffuser for controlling the discharge direction of the inflation gas and also as a member for fixing the inflator 31 to the side frame portion 17 together with the airbag 40. most parts of the container 32 are formed in a substantially cylindrical shape extending in a substantially vertical direction obtained by bending a plate such as a metal sheet. The container 32 is provided with a communication portion (not shown) for connecting inner and outer sides of the container. Most parts of the inflation gas discharged from the inflator 31 are discharged to the outside from the container 32 via the communication portion.The container 32 is secured to the side frame 17 by a securing member such as bolts 34.The inflator assembly 30 may be configured such that the inflator 31 and the container 32 are integrally formed in one piece.Airbag 40As illustrated by the dashed / two-dot lines in FIGS. 1, 2 to 3, when an impact is applied to the side wall 11 from a lateral direction due to a side collision or the like while the vehicle 10 is traveling, the airbag 40 is supplied with the inflation gas from the inflator 31 and therefore deployed and inflated, so that the airbag 40 is jumped out from the seat back 14 in a state where a portion of the airbag 40 remains in the seat back 14.FIG. 5 is a side view illustrating the airbag module AM in a state (hereinafter referred to as an unfilled deployed state) in which the airbag 40 is deployed in a flat shape without being filled with the inflation gas. FIG. 7 illustrates the internal structure of the airbag module AM together with the occupant P and the seat 12, the airbag 40 being cut at the center of the lateral direction of the vehicle in the non-inflated, deployed, or deployed state in FIG. 5.As illustrated in FIGS. 5, 6 to 7, the airbag 40 is formed by folding one fabric layer (base fabric, also known as a fabric sheet) halfway along a fold line 42 disposed on a center line of the fabric to superimpose the fabric in the vehicle transverse direction, and then connecting the superimposed portions of the fabric to form the shape of a bag. To distinguish two superposed portions of the airbag 40, the fabric placed on the vehicle inner side is referred to as the fabric portion 43, and the fabric placed on the vehicle outer side is referred to as the fabric portion 44. Each of the fabric portions 43 and 44 is formed in a vertically elongated shape with respect to the front and rear direction.According to this embodiment, the fabric is folded halfway such that the fold line 42 is located at a rear end of the airbag 40, but the fabric may be folded halfway such that the fold line 42 is located at another end of the airbag 40, for example, a front end, an upper end, or a lower end thereof. Also, the air bag 40 may be comprised of two panels of fabric divided along the fold line 42. In this case, the airbag 40 is formed by laying one fabric part on the other in the vehicle transverse direction and connecting the two fabric parts to form the shape of a bag. Further, the airbag 40 may be made of three or more fabric pieces.In the airbag 40, the appearance of the two fabric portions 43 and 44 is axis-symmetrical with respect to the fold line 42. the shape and size of each fabric portion 43 and 44 are configured such that the airbag 40 includes the region corresponding to the region from the chest region PT to the head PH in the upper body of the occupant P seated in the vehicle seat 12 when the airbag 40 is deployed and inflated between the vehicle seat 12 and the side wall 11 (see FIGS. 1, 2 to 3 ). As illustrated in FIG. 7, the airbag 40 is configured such that a front end 40 aof the portion corresponding to a side of the head PH of the occupant P is positioned in front of the front end 40 bof the portion corresponding to a side of the chest region PT.A material suitable for the above-mentioned fabric portions 43 and 44 includes a woven fabric made of, for example, a polyester yarn or polyamide yarn, which has high strength and flexibility and can be easily folded.The two fabric portions 43 and 44 are joined together along a peripheral edge joint portion 45 provided at peripheral edges of the fabric portions 43 and 44. In this embodiment, most of the peripheral edge connecting portion 45 is formed by stitching (sewing together with a sewing thread) the peripheral edges of the fabric portions 43 and 44 except for the rear ends thereof (i.e., the vicinity of the fold line 42). The configuration formed by the stitching is similar to an outer connection portion 52 and an inner connection portion 53 described later.In FIGS. 5, 7 to 15B, 17 and 18, the stitched portions of the airbag 40 are represented by three kinds of lines. The first of these lines is a line (a kind of broken line) represented by intermittently aligning or directionally arranging thick lines of a given length, and it shows the quilted portions as viewed from the airbag 40 side (see the peripheral edge connecting portion 45 or the like in FIG. 5 ). The second of these lines is a line (a kind of broken line) represented by intermittently aligning or directionally arranging thin lines of a given length (longer than a general broken line), and it shows a state in which the sewing thread is positioned between the fabric portions 43 and 44 and therefore is not directly seen (hidden) (see the inner connecting portion 53 or the like in FIG. 5 ). The third of these lines is a line (a kind of broken line) represented by aligning or aligning points at regular intervals, and it shows a cross section of the suture that stitches the fabric portions 43 and 44 together (see the peripheral edge connecting portion 45 in FIG. 7 ).As shown in FIGS. 5, 6 to 7, the space enclosed by the peripheral edge connecting portion 45 between the two fabric portions 43 and 44 forms a inflation portion deployed and inflated by the inflation gas on the upper body side of the occupant P to protect the region extending from the chest region PT and the head PH from the shock.In this case, the peripheral edge connecting portion 45 may be formed by a means other than the stitching using the suture, for example, by bonding using an adhesive. The configuration formed by the bonding is similar to the outer joint portion 52 and the inner joint portion 53 described later.The airbag 40 is provided with a partition 50 at the inner central portion thereof in a longitudinal direction, and the partition extends in a substantially vertical direction. Therefore, the airbag 40 is divided into a rear inflation chamber 46 at a position rearward of the partition 50, and a front inflation chamber 47 at a position forward of the partition 50. The partition 50 has the same configuration as one generally referred to as a link ("tether").Division 50The partition 50 comprises a pair of fabric parts 51 of a material having high strength and flexibility and being easily folded, for example, the same woven fabric as the fabric portions 43 and 44. Each fabric member 51 is connected to the opposite one of the two fabric portions 43 and 44 of the airbag 52 through the outer connecting portion 52 extending in the substantially vertical direction along the rear edge thereof. When the airbag 40 is inflated, the two outer joint portions 52 are joined to the fabric portions 43 and 44 corresponding to the rear end of the fabric part 51 at the portion that is the side of the central portion in the horizontal direction in the upper body of the occupant P. Both fabric pieces 51 are joined together by the inner joint portion 53 extending in the substantially vertical direction along the front edge thereof.The partition 50, which is made of a pair of fabric pieces 51, is interposed between the vehicle inner side fabric portion 43 and the vehicle outer side fabric portion 44 in the airbag 40. The partition 50 is in the superimposed state in the vehicle lateral direction when the airbag 40 is in the non-inflated deployed state (see FIGS. 5 and 7 ). Also, the partition 50 is strained in the vehicle lateral direction when the airbag 40 is inflated (see FIG. 6 ), and therefore, limits the thickness (inflation thickness) of the airbag 40 in the vehicle lateral direction.The partition 50 is provided with an upper communication hole 54 for communicating the rear inflation chamber 46 and the front inflation chamber 47 in the portion that is the head PH side of the occupant P when the airbag 40 is inflated. Also, the partition 50 is provided with a lower communication hole 55 for communicating the rear inflation chamber 46 and the front inflation chamber 47 at the portion that is the chest region PT side of the occupant P when the airbag 40 is inflated. Specifically, the inner connecting portion 53 connecting both fabric parts 51 is not engaged at two portions, i.e., the upper end and the lower end, in the vertical direction. The upper end and the lower portion in the vertical direction are not provided with the inner connecting portion 53 connecting the two fabric parts 51. The upper end non-engagement portion of the inner connection portion 53 forms the upper communication hole 54 and the lower portion non-engagement portion of the inner connection portion 53 forms the lower communication hole 55. The upper communication hole 54 and the lower communication hole 55 are closed in the state where both fabric parts 51 are superposed and opened in the state where the partition 50 is strained in the lateral direction of the vehicle when the airbag 40 is inflated.In the state where the airbag 40 is in the non-inflated deployed state, i.e., the fabric parts 51 are superposed on the partition 50, the vertical length L 1 of the lower communication hole 55 is longer than the vertical length L 2 of the upper communication hole 54.Most of the above-described inflator assembly 30 is housed in the lower portion of the rear end of the rear inflation chamber 46, the inflator assembly extending in a substantially vertical direction. The bolt 34 of the container 32 is inserted into the vehicle inner side fabric portion 43 of the airbag 40. With the insertion, the inflator assembly 30 is locked in a state of positioning with respect to the airbag 40.Further, the vehicle exterior side fabric portion 44 serves as the front portion of the front inflation chamber 47, and has a vent hole 56 between the upper communication hole 54 and the lower communication hole 55. The fabric portion 44 is provided with a reinforcing portion 57 in the vicinity of the vent hole 56, and the reinforcing portion 57 is formed by stitching it with the suture. The reinforcing portion 57 reinforces the vicinity of the vent hole 56 of the fabric portion 44 to prevent the portion from being burst or loosened.As illustrated in FIGS. 4, 15A, and 15B, the airbag module AM including the inflator assembly 30 and the airbag 40 as main components thereof is configured to have a compact shape (hereinafter referred to as a storage shape) in which the airbag 40 is folded. This serves to fit the airbag module AM into the restricted-size accommodation portion 21 in the seat back 14 for the purpose of appropriate accommodation.The storage shape is obtained by folding the airbag 40 of the non-inflated deployed state as shown in FIGS. 8 to 15B. Next, a process of folding the airbag 40 will be described, and specifications regarding the positions of the fold lines 42, 61, 64, 67, 71, 74, and 75, the positions of the portions to be folded, the folding direction, or the like are necessary. For this reason, when the positions of the fold lines or the positions of the portions to be folded are specified, each portion of the airbag 40 is specified based on the inflator assembly 30. With respect to a direction (substantially vertical direction) along an axis AL of the inflator assembly 30, the end near the inflator assembly 30 is referred to as a first distal portion, while the end remote from the inflator assembly 30 is referred to as a first proximal portion. In the state where the airbag 40 of the non-inflated deployed state is attached to the vehicle seat 12, the first distal portion corresponds to the lower end of the airbag 40 and the first proximal portion corresponds to the upper end of the airbag 40.Similarly, the direction (substantially horizontal direction) perpendicular to the axis AL of the inflator assembly 30 is referred to as a second distal portion, while the end thereof remote from the inflator assembly 30 is referred to as a second proximal portion. In the state where the airbag 40 of the non-inflated deployed state is attached to the vehicle seat 12, the second distal portion corresponds to the rear end of the airbag 40 and the second proximal portion corresponds to the front end of the airbag 40.When the folding direction is specified, the words "vehicle outer side" and "vehicle inner side" are used, assuming that the airbag 40 is mounted on the vehicle seat 12.FIG. 8 shows the airbag 40 of the non-inflated deployed state as viewed from the vehicle exterior side, with the axis AL of the inflator assembly 30 and the fold line 42 extending in the vertical direction. In the airbag 40, a fold line 61 perpendicular to the fold line 42 is disposed at a portion slightly spaced from the inflator assembly 30 toward the first proximal portion (upper side of FIG. 8 ). In the airbag 40, as indicated by the arrow in FIG. 8, the portion of the first proximal portion (upper side of FIG. 8 ) except the fold line 61 is folded back toward the vehicle outer side (front side of FIG. 8 ) along the fold line 61. By folding back the portion 62, a part of the portion 62 is overlapped with a part of the portion 63 of the first distal portion (lower side of FIG. 8 ) except the fold line 61. Therefore, the airbag 40 is formed as shown in FIGS. 9A and 9B.Next, in the portion 62, the fold line 64 parallel to the fold line 61 is set at the portion spaced from the fold line 61 toward the first proximal portion (lower side of FIG. 9A ). In the portion 62, as indicated by the arrow in FIG. 9A, the portion 65 of the first proximal portion (lower side of FIG. 9A ) except the fold line 64 is folded back toward the vehicle outer side (front side of FIG. 9A ) along the fold line 64. By folding back the portion 65, a part of the portion 65 is overlapped with a part (hereinafter referred to as a folded portion 66) of the airbag 40 which is pinched between the fold line 61 and the fold line 64. Therefore, the airbag 40 is formed as shown in FIGS. 10A and 10B.The fold line 67 parallel to the fold line 64 is established at the portion of the portion 65 spaced from the fold line 64 toward the first proximal portion (upper side of FIG. 10A ). In the portion 65, as indicated by the arrow in FIG. 10A, the portion (hereinafter referred to as folded portion 68) of the first proximal portion (upper side of FIG. 10A ) except the fold line 67 is folded back toward the vehicle inner side (rear side of FIG. 10A ) along the fold line 67. By folding back the portion 68, most of the portion 68 is overlapped with a part (hereinafter referred to as a folded portion 69) of the airbag 40 which is pinched between the fold line 64 and the fold line 67. Therefore, the airbag 40 is formed as shown in FIGS. 11A and 11B.FIGS. 12A and 12B show the airbag 40 in FIGS. 11A and 11B as viewed from a rear side thereof, i.e., as viewed from the vehicle inner side. As illustrated in FIGS. 12A and 12B, the fold line 71 is disposed at the portion 63 of the airbag 40 in which the inflator assembly 30 is accommodated. The fold line 71 is disposed at the second proximal portion (front end side) with respect to the direction perpendicular to the axis AL of the inflator assembly 30, which is the deployment direction of the airbag 40. The fold line 71 is arranged to be inclined with respect to the axis AL. In the portion 63, as indicated by the arrow in FIG. 12A, the portion (hereinafter referred to as the folded portion 72) of the second proximal portion (obliquely left lower side in FIG. 12A ) except the fold line 71 is folded back toward the vehicle inner side (front side of FIG. 12A ). By folding back the portion, the folded portion 72 is overlapped with a portion (hereinafter referred to as folded portion 73) enclosed by the fold line 71, the fold line 42 and the fold line 61 in portion 63. In the airbag 40, as illustrated in FIGS. 13A and 13B, the folded portions 69, 68, 66, 73, and 72 are superposed with each other toward the vehicle inner side from the vehicle outer side.As illustrated in FIGS. 13A and 13B, the fold lines 74 parallel to the fold line 42 (axis AL) are arranged at a plurality of portions in a region Z 1 of the second proximal portion (front end side) except the partition 50 (outer connection portion 52) of the airbag 40 of the intermediate shape with respect to the direction perpendicular to the axis AL of the inflator assembly 30.The region Z 1 is folded toward the second distal portion (rear end side) from the second proximal portion (front end side) by a roll fold manner that repeatedly folds the region in the same direction along each fold line 74. By the folding, the airbag 40 is folded as shown in FIGS. 14A and 14B.As illustrated in FIGS. 14A and 14B, the fold lines 75 parallel to the fold line 42 (axis AL) are arranged at a plurality of portions in an area Z 2 of the second distal portion (rear end side) except the partition 50 (outer connection portion 52) of the airbag 40 that is roll-folded with respect to the direction perpendicular to the axis AL. The region Z 2 is folded toward the second distal portion (rear end side) from the second proximal portion (front end side) by a bellows fold manner that alternately changes the fold-back direction along each fold line 75. By the folding, the airbag 40 is formed in the storage shape as shown in FIGS. 15A and 15B.The airbag module AM of the storage shape formed by folding the airbag 40 is of reduced size in the direction (substantially horizontal direction) perpendicular to the direction (substantially vertical direction) with respect to the axis AL of the inflator assembly 30, and is therefore suitable for accommodation in the narrow accommodation portion 21 of the seat back 14.In the airbag module AM of the storage shape, as shown in FIG. 4, the bolt 34 extending from the case 32 and inserted into the airbag 40 (fabric portion 43) is inserted into the side frame portion 17. Since the nut 35 is fastened to the bolt 34, the inflator assembly 30 is fastened to the side frame portion 17 together with the airbag 40.In this case, the inflator assembly 30 may be fixed to the side frame portion 17 by a member different from the bolt 34 and the nut 34 described above.As illustrated in FIG. 1, the side airbag device includes an impact sensor 81 and a control device 82 in addition to the above-described airbag module AM (see FIG. 2 ). The impact sensor 81 includes an acceleration sensor or the like, and is installed on the side wall 11 of the vehicle 10 (see FIG. 2 ) or the like to detect the impact applied to the side wall 11 from the side. The controller 82 controls the operation of the inflator 31 in response to the signal detected by the impact sensor 81.Although the vehicle 10 is provided with a seat belt device for restraining the occupant P seated in the vehicle seat 12 in the vehicle seat 12, such a seat belt device is not shown in FIG. 1 or the like.Next, the operation of the side airbag device including the configuration according to this embodiment will be described.According to the side airbag device, when no impact is applied to the side wall 11 of the vehicle 10 from the lateral direction due to the side collision or the like, no operation signal is output from the control device 82 to the inflator 31 to operate the inflator 31, and therefore no inflation gas is supplied from the inflator 31 to the airbag 40. The airbag module AM is still accommodated in the accommodation portion 21 as the storage shape (see FIG. 4 ).When an impact of a given or larger value is applied to the side wall 11 from the lateral direction due to the side collision or the like during traveling of the vehicle and then detected by the impact sensor 81, an operation signal is output from the controller 82 to the inflator 31 to operate the inflator 31 in response to the detected signal. In response to the operation signal, a gas generating agent generates the high-pressure inflation gas in the gas generator 31 and then the inflation gas is discharged therefrom. The discharged inflation gas is supplied to the airbag 40 through the communication portion of the container 32. Here, the airbag 40 is partitioned into the rear inflation chamber 46 and the front inflation chamber 47 by the partition 50 provided at the central portion in the longitudinal direction thereof, and the inflator assembly 30 is disposed at the lower portion of the inner rear end of the rear inflation chamber 46. For this reason, the inflation gas from the inflator 31 is supplied to the lower portion of the inner rear end of the rear inflation chamber 46.As illustrated in FIG. 17, the inflation gas in the rear inflation chamber 46 flows from the folded portion 73 adjacent to the inflator assembly 30 toward the folded portions 68 and 72 away from the inflator assembly. Also, the inflation gas in the rear inflation chamber 46 flows forward from the second distal portion folded portion 73 (rear end side) toward the second proximal portion folded portion 72 (front end side) with respect to the deploying direction. The folded portion 73 of the first distal portion and the second distal portion is the folded portion in which the inflator assembly 30 is accommodated.When the inflation gas flowing from the second distal portion toward the folded portion 72 of the second proximal portion arrives at the partition 50, the flow direction rotates upward along the partition 50, and the inflation gas then joins the inflation gas flowing upward from the beginning.By the filling gas flowing upward, the rear filling chamber 46 is filled while being sequentially unfolded (deployed) from the bottom upward.Also, by the inflation gas flowing forward, the bellows-folded portion Z 2 (see FIGS. 14A and 14B ) of the airbag 40 behind the partition 50 is inflated while being sequentially unfolded (deployed) from the rear to the front.As described above, when the airbag 40 is deployed and inflated upward and forward, the seat pad 18 of the seat back 14 is pushed by the airbag 40, and therefore the breakable portion 23 in FIG. 4 is broken. As illustrated in FIG. 16, the airbag 40 jumps out of the seat back 14 in the substantially forward direction of the vehicle 10 in a state where the rear end of the airbag 40 remains in the accommodation portion 21 together with the inflator assembly 30.The inflation gas inflates the portion (behind the partition 50) of the proximal portion folded portion 72 (front end side).Bellows folding is characterized in that the folded state is easily released. For this reason, the bellows-folded region Z 2 behind the partition 50 is rapidly deployed and filled forward.The volume of the rear inflation chamber 46 is smaller than that of the airbag 40 in the case where the airbag 40 is not partitioned by the partition 50. This is also the case.Inflation thickness of the rear inflation chamber 46 with respect to the vehicle width direction is smaller than that of the airbag 40 in the vehicle width direction in the case where the airbag 40 is not partitioned. For this reason, the rear filling chamber 46 is easily unfolded and filled while passing through the narrow space.As illustrated in FIGS. 7 and 17, a part of the inflation gas that flows upward in the rear inflation chamber 46 and arrives at the rear portion side of the chest portion PT of the occupant P flows downward through the lower communication hole 55 in the front inflation chamber 47. Also, a part of the inflation gas that flows upward in the rear inflation chamber 46 above the lower communication hole 55 without passing through the lower communication hole 55 and arrives at the rear portion side of the head PH of the occupant P flows upward through the upper communication hole 54 in the front inflation chamber 47. In this case, since the opening area of the lower communication hole 55 is larger than that of the upper communication hole 54, the inflation gas flows through the lower communication hole 55 in an amount larger than that of the inflation gas flowing through the upper communication hole 54.A part of the inflation gas flowing into the front inflation chamber 47 through the lower communication hole 55 turns up and down. Also, a part of the inflation gas flowing into the front inflation chamber 47 through the upper communication hole 54 turns downward.By the inflation gas, the roll-folded portion before the partition 50 is deployed and inflated forward on the front portion side of the chest region PT or the head PH. In this case, as described above, since the flow rate of the inflation gas through the lower communication hole 55 and the upper communication hole 54 is different, the portion to be deployed and inflated on the front portion side of the head PH is deployed and inflated hardly earlier than other portions, particularly the chest region PT side, i.e., is deployed and inflated hardly early before passing the portion of the narrow clearance between the shoulder PS of the occupant P and the side wall 11 of the vehicle. The portion to be deployed and inflated on the side of the front portion of the head PH is deployed and filled after passing the portion of the narrow space between the shoulder PS and the side wall 11. As a result, since the portion of the airbag 40 to be deployed and inflated on the side of the head PH can hardly pass the portion of the narrow space, a phenomenon of interfering with the deployment and inflation of other portions hardly occurs. The airbag 40 is deployed and inflated on the side of the region extending from the chest region PT to the head PH of the occupant P.Also, the roll folding is characterized in that the folded portion is easily unfolded or deployed along the side wall 11 of the vehicle. For this reason, the roll-folded portion is deployed and filled forward before the partition 50 along the side wall 11 of the vehicle on the side of the front portion of the chest region PT or the head PH of the occupant P.When the inflation gas flowing into the front inflation chamber 47 through the lower communication hole 55 turns in the downward direction and then is supplied to the portion (before the partition 50) of the folded portion 72 of the second proximal portion (front end side), the folded portion 72 folded back toward the vehicle inner side is unfolded (deployed). During the deploying, since the folded portion 72 does not come into contact with the side wall 11 of the vehicle, the unimpeded deploying is hardly interrupted due to the friction with the side wall 11, and also the portion (before the division 50) of the folded portion 72 is pushed by the portion behind the division 50 that starts to be filled early as described above, so that the deploying is performed quickly.When the inflation gas flowing upward in the rear inflation chamber 46 arrives at the folded portion 68 of the first proximal portion (upper end side), the folded portion 68 folded back toward the vehicle inner side is unfolded (deployed). During the deploying, since the folded portion 68 does not come into contact with the side wall 11 of the vehicle 10, the unimpeded deploying is hardly interrupted due to the friction with the side wall 11.As illustrated in FIG. 7, when the airbag 40 is fully deployed and inflated, the front end 40 apositioned on the head PH side of the occupant P is positioned forward of (positioned closer to the front of the vehicle than the) the front end 40 bpositioned on the chest region PT side. For this reason, the area of the airbag 40 deployed and inflated on the side of the head PH is widened forward as compared with the area positioned at the same portion as the front end 40 bof the airbag 40 or positioned behind the front end 40 b.However, when the upper communication hole 54 is positioned at the folded portion other than the uppermost folded portion 68, for example, the folded portion 69, the inflation gas flows into the front inflation chamber 47 through the upper communication hole 54 to fill the front inflation chamber 47, which may stop the unfolding and inflation of the folded portion 68 that is performed later.In view of this, in this embodiment, since the upper communication hole 54 is positioned at the uppermost folded portion 68, the inflation gas in the rear inflation chamber 46 flows into the front inflation chamber 47 through the upper communication hole 54 in the process in which the folded portion 68 is deployed. Therefore, the unfolding and filling of the folded portion 68 is hardly interrupted due to the upper communication hole 54.The airbag 40 deployed and inflated as described above is sandwiched between the occupant P and the side wall 11 moving toward the vehicle inner side as indicated by the broken / two-dot lines in FIGS. 2 and 3, thereby directly pushing and restraining the occupant P toward the vehicle inner side and, at the same time, suppressing the shock applied to the occupant P from the lateral direction by the side wall 11.In this case, the inflation gas that flows into the upper portion of the front inflation chamber 47 through the upper communication hole 54 and turns downward is discharged to the outside (outside of the vehicle except the fabric portion 44) of the airbag 40 through the vent hole 56. Since the internal pressure is reduced by the discharge of the inflation gas, the shock applied to the occupant P from the lateral direction by the side wall 11 is alleviated. Also, since the inflation gas that deploys and inflates the upper portion of the front inflation chamber 47 as described above is discharged from the vent hole 56, the inflation gas is prevented from flowing to the lower portion of the front inflation chamber 47 located below the vent hole 56. As a result, the lower portion of the front inflation chamber 47 is prevented from being deployed and inflated due to the excessive pressure applied from the lateral direction of the chest region PT.According to the above-described embodiment, the effects given below are obtained.(1) The airbag 40 is divided into the front inflation chamber 47 before the partition 50 and the rear inflation chamber 46 behind the partition 50 by the partition 50 extending in the substantially vertical direction, and the inflator 31 is disposed at the lower portion of the rear inflation chamber 46. The partition 50 is provided with the upper communication hole 54 for communicating rear inflation chamber 46 and front inflation chamber 47 at the portion that is the head PH side of the occupant P, and is provided with the lower communication hole 55 for communicating rear inflation chamber 46 and front inflation chamber 47 at the portion that is the chest region PT side of the occupant P. The opening area of the lower communication hole 55 is configured to be larger than that of the upper communication hole 54 (see FIG. 7 ).For this reason, since the phenomenon occurs in which the portion of the airbag 40 to be deployed and inflated on the head PH side hardly passes through the narrow space between the shoulder PS of the occupant P and the side wall 11 of the vehicle 10, the airbag 40 is properly deployed and inflated on the region side extending from the chest region PT to the head PH of the occupant P.(2) The front inflation chamber 47 is provided with the vent hole 56 for exhausting the inflation gas between the upper communication hole 54 and the lower communication hole 55 (see FIG. 7 ).For this reason, the inflation gas that deploys and inflates the upper portion of the front inflation chamber 47 flows to the portion that is the chest region PT side, thereby preventing the portion from being deployed and inflated due to the excessive pressure.(3) When the airbag 40 is fully deployed and inflated, the front end 40 aof the airbag 40, which is positioned on the head PH side of the occupant P, is positioned forward of (positioned closer to a front side of the vehicle than the) the front end 40 b, which is positioned on the chest region PT side of the occupant P (see FIG. 7 ).For this reason, the area of the airbag 40 deployed and inflated on the side of the head PH is expanded forward, whereby the head PH of the occupant P is caught by the airbag 40 and the effect of protecting the occupant from the shock is improved.(4) The airbag 40 is provided with the plurality of folded portions 66, 68, 69, and 73 formed by folding the airbag from top to bottom before the airbag is deployed and inflated. The upper communication hole 54 of the partition 50 is positioned at the uppermost folded portion 68 that is the farthest upward from the inflator 31 in the airbag 40 (see FIG. 17 ).For this reason, in the process in which the uppermost folded portion 68 is deployed, the inflation gas in the rear inflation chamber 46 flows into the front inflation chamber 47 through the upper communication hole 54, so that interruption of the deployment and inflation of the uppermost folded portion 68 due to the upper communication hole 54 can be prevented.The embodiment may be modified as indicated below.The opening area of the lower communication hole 55 may be set to be equal to that of the upper communication hole 54. In this case, the same effect as that of the embodiment is obtained.The vent hole 56 may be formed in other shapes other than a circle, for example, a slit shape.The inflator 31 may be directly attached to the side frame 17 without the use of the container 32.The almost entire part of the airbag 40 may be inflated as in the embodiment, but the airbag 40 may be provided with a non-inflation portion that is not supplied with the inflation gas and thus is not inflated.The partition 50 may be formed of a fabric partition.Instead of the seat back 14 of the vehicle seat 12, the side wall 11 may be provided with a portion corresponding to the accommodation portion 21, and the airbag module AM may be inserted therein.The portion of the airbag 40 that is the shoulder PS side of the occupant P may be provided with a thickness decreasing portion for decreasing the inflation thickness in the lateral direction of the vehicle from that of other portions during inflation.For example, as indicated by the thick broken lines in FIG. 18, a connecting portion 86 (also referred to as a seam) for connecting the portions that are the shoulder PS side of the occupant P or the vicinity thereof may be provided from the two fabric portions 43 and 44 of the airbag 40, and the connecting portion 86 may serve as a thickness decreasing portion. In FIG. 18, the connecting portion 86 extending from a portion of the partition 50 to a portion adjacent to the partition 50 in the state where a pair of fabric pieces 51 are overlapped with each other when the airbag 40 is not inflated is provided in a hook shape, but the connecting portion 86 may be provided at other portions. At the portion provided with the connecting portion 86, the airbag 40 has a substantially zero inflation thickness.When the portion, which is the shoulder PS side of the occupant P, of the front end 40 cof the airbag 40 or the vicinity thereof is changed to a position indicated by the broken / two-dot chain line in FIG. 18, a concave portion 87 may be provided at the portion, which is the shoulder PS side or the vicinity thereof, as the front end of the airbag 40, and the concave portion 87 may serve as the thickness decreasing portion. At the portion provided with the concave portion 87, the airbag 40 has a substantially zero inflation thickness.In each case described above, the inflation thickness of the portion that is the shoulder PS side of the occupant P or the vicinity thereof through the connecting portion 86 or the concave portion 87 in the lateral direction of the vehicle is smaller than the other positions. For this reason, the portion of the airbag 40 that is the shoulder PS side of the occupant P can be easily deployed and inflated without being caught even by the portion of the narrow space between the shoulder PS and the side wall 11 of the vehicle 10, so that the airbag 40 is freely deployed and inflated.Vehicles for which the side airbag device is used include various commercial to private vehicles used for transportation.Next, technical ideas obtained by the above-described embodiments will be described together with the effects thereof.(A) In the side airbag device according to the third aspect, the airbag is formed by superimposing the fabric portion of the vehicle inner side with the fabric portion of the vehicle outer side and connecting the fabric portions along the circumferential edges thereof, and the thickness decreasing portion is composed of the connecting portion for connecting the portions, which are the sides of the shoulder of the occupant or the vicinity thereof, of both the fabric portions in the state where the portions come into contact with or come close to each other.According to the configuration described above, since the connection portion is provided, the airbag portion, which is the side of the occupant's shoulder, has a inflation thickness of about zero, thereby obtaining the effect indicated in the third aspect.(B) In the side airbag device according to the third aspect, the thickness decreasing portion is composed of the concave portion provided at the front end of the airbag and concaved rearward from the edge of the front end.According to the configuration described above, since the concave portion is provided, the airbag portion, which is the side of the occupant's shoulder, has a inflation thickness of zero, thereby obtaining the effect indicated in the third aspect.

Claims

A side airbag device comprising a inflator (30) for ejecting a inflation gas in response to an impact applied from a lateral direction of a vehicle (10), and an airbag (40) accommodated in a folded state and deployed and inflated by the inflation gas from the inflator (30) between an occupant (P) seated in a vehicle seat (12) and a side wall (11) of the vehicle (10) in a region extending from a chest region (PT) to the head (PH) of the occupant (P), wherein the airbag (40) is divided into a front inflation chamber (47) and a rear inflation chamber (46) by a partition (50) extending in a substantially vertical direction, the inflator (30) is disposed at a lower portion of the rear inflation chamber (46), the partition (50) is provided with an upper communication hole (54) for communicating rear inflation chamber (46) and front inflation chamber (47) at a portion which is a head (PH) side of the occupant (P), the partition (50) is provided with a lower communication hole (55) for communicating rear inflation chamber (46) and front inflation chamber (47) at a portion which is a chest region (PT) side of the occupant (P), and an opening area of the lower communication hole (55) is configured to be larger than that of the upper communication hole (54).The side airbag device according to claim 1, wherein the front inflation chamber (47) is provided with a vent hole (56) for releasing the inflation gas between the upper communication hole (54) and the lower communication hole (55).The side airbag device according to claim 1 or 2, wherein the side airbag device includes a thickness decreasing portion (86;87) provided at a portion of the airbag (40) that is located at a side of a shoulder (PS) of the occupant (P) and that decreases a inflation thickness in a lateral direction of the vehicle (10) from other portions of the airbag (40) during inflation.The side airbag device according to any one of claims 1 to 3, wherein, when the airbag (40) is fully deployed and inflated, a front end (40a) of a portion of the airbag (40) positioned on the head (PH) side of the occupant (P) is positioned closer to a front side of the vehicle (10) than a front end (40b) of a portion of the airbag (40) positioned on the chest region (PT) side of the occupant (P).The side airbag device according to any one of claims 1 to 4, wherein the airbag (40) is provided with folded portions (66,68,69,73) formed by folding the airbag (40) from top to bottom, and the upper communication hole (54) of the partition (50) is positioned at the uppermost folded portion (68).

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