Passenger seat airbag

Abstract

Passenger seat airbag, comprehensive a bag main body (16) configured to be folded and accommodated in an accommodation portion (12) formed in a dashboard disposed in front of the passenger seat of a vehicle, and which, when an inflation gas is supplied therein, can be inflated so as to protrude toward the rear of the vehicle, and a holding belt (29) arranged within the bag main body (16) and configured to restrict the shape of the bag main body (16) at the time of its full inflation, wherein the bag main body (16) includes a passenger-side wall portion (25) arranged to be located substantially along the vertical direction on the rear end side of the bag main body (16) at the time of full inflation, and a peripheral wall portion (17) shaped to extend forward from the outer peripheral edge of the passenger-side wall portion (25) and converge toward the front end of the bag main body (16), the peripheral wall portion (17) including, on the front lower surface side thereof, a gas supply opening (18) opened to allow inflation gas to flow therethrough and having a peripheral edge mounted on the side of the accommodation portion (12), and the retaining strap (29) with the rear edge side (19b) of the gas supply opening (18) and extends rearwardly therefrom, and at the time of full inflation, a rear end side thereof is connected to the vicinity of the center of the passenger-side wall portion (25), thereby limiting the distance of the passenger-side wall portion (25) from the gas supply opening (18) at the time of full inflation of the bag main body (16), characterized in that a cover layer (40) formed of a band-shaped flexible layer member and arranged above the gas supply opening (18) is provided, the front end side (40a) of the cover layer (40) being connected to the front edge side (19a) of the gas supply opening (18) and the rear end side (40b) of which is connected to the tether (29) so that the inflation gas is deflected in the lateral direction and the inflation gas is prevented from flowing directly toward the passenger-side wall portion (25).

Description

BACKGROUND 1. Field of the invention

[0001] The invention relates to a passenger seat airbag which is folded and housed in an accommodating portion formed in an instrument panel disposed in front of the passenger seat of a vehicle and which, when an inflation gas is supplied therein, can be inflated so as to protrude toward the rear of the vehicle. 2. Description of the state of the art

[0002] DE 41 42 326 A1 discloses an airbag for a motor vehicle. US 2006 / 0 175 819 A1 discloses an airbag. US 2003 / 0 107 205 A1 discloses an airbag.

[0003] Conventionally, a passenger seat airbag is known which is structured such that a tether for restricting the rearward projection of a passenger side wall portion is disposed within a bag main body which is inflatable when an inflation gas is supplied thereinto, so as to be located on the rear end side of the bag main body at the time of full inflation (see, for example, JP 2008 - 254 500 A).In this passenger seat airbag, the tether extends rearward from the rear edge side of a gas supply port whose peripheral edge is to be mounted on the accommodating portion side of the airbag main body, and the rear end side of the tether is connected to the passenger side wall portion, thereby restricting the separation distance of the passenger side wall portion from the gas supply port at the time of full inflation of the bag main body and consequently restricting the shape of the airbag main body at the time of full inflation.

[0004] In the conventional passenger seat airbag, although the separation distance of the vicinity of the center of the passenger side wall portion from the gas supply port at the time of full inflation of the bag main body can be restricted, the lateral two sides of the tether connected portion of the passenger side wall portion cannot be prevented from greatly protruding toward the rear of the vehicle at an early stage of inflation of the bag main body, so that there remains a need for improvement in restricting the great protrusion of the bag main body toward the rear of the vehicle at an early stage of inflation. SUMMARY

[0005] The invention aims to solve the above problem and, accordingly, it is an object of the invention to provide a passenger seat airbag which can be quickly deployed and inflated while preventing excessive protrusion toward the rear of the vehicle at an early stage of inflation.

[0006] According to one aspect of the invention, there is provided a passenger seat airbag comprising: a bag main body to be folded and accommodated in an accommodation portion formed in an instrument panel located in front of the passenger seat of a vehicle, and which, when an inflation gas is supplied therein, can be inflated so as to protrude toward the rear of the vehicle; and a tether disposed inside the bag main body and configured to restrict the shape of the bag main body at the time of its full inflation; wherein the bag main body includes a passenger-side wall portion arranged to be located substantially along the vertical direction on the rear end side at the time of full inflation; and a peripheral wall portion shaped so as tothat it extends forward from the outer peripheral edge of the passenger-side wall portion and converges toward the front end, wherein the peripheral wall portion includes, on the front lower surface side thereof, a gas supply port which is opened so that the inflation gas can flow therethrough and which has a peripheral edge which can be mounted on the side of the accommodation portion, and the tether extends rearward from the rear edge side of the gas supply port and, at the time of full inflation, a rear end side thereof is connected to the vicinity of the center of the passenger-side wall portion, thereby restricting the distance of the passenger-side wall portion from the gas supply port at the time of full inflation of the bag main body, characterized in that a cover layer,which is formed from a band-shaped flexible layer element and can be arranged above the gas supply opening, wherein the front end side of the cover layer is connected to the front edge side of the gas supply opening and the rear end side thereof is connected to the retaining belt.,

[0007] According to the passenger seat airbag of the invention, the cover sheet, whose front end side is connected to the front edge side of the gas supply port and whose rear end side is connected to the tether, can be arranged above the gas supply port. Thus, in the early stage of airbag inflation, when the inflation gas flows into the airbag through the gas supply port, the inflation gas flowing toward the rear side (toward the passenger-side wall portion) impacts the cover sheet and is deflected to move in the lateral direction. Consequently, the inflation gas supplied from the gas supply port can be prevented from directly flowing toward the passenger-side wall portion, and the inflation gas deflected in the lateral direction allows the bag main body to expand widely in the lateral direction.

[0008] Therefore, according to the passenger seat airbag of the invention, the two lateral side portions on the central side of the passenger-side wall portion, with the tether connected thereto, can be prevented from excessively protruding rearward at an early stage of airbag inflation. Furthermore, since the cover sheet can be pushed upward by the inflation gas supplied from the gas supply port so as to flow rearward (toward the passenger-side wall portion), the central portion of the cover sheet is pushed upward by the inflation gas, so that the cover sheet is curved, thereby pulling its rear end side portion connected to the tether forward. Consequently, the tether can be pulled forward by the cover sheet, thereby preventing the rear end of the tether from excessively moving rearward at an early stage of bag main body inflation.

[0009] As a result, according to the passenger seat airbag of the invention, at an early stage of inflation of the bag main body, the cover sheet can deflect the direction of the inflation gas and prevent the tether from moving backward. Consequently, at an early stage of inflation, while preventing the bag main body from expanding in the lateral direction, the bag main body can be appropriately prevented from expanding in a manner that greatly protrudes rearward from the passenger-side wall portion. When the bag main body inflates and its inflation is almost complete, the flow velocity of the inflation gas flowing therein through the gas supply port is also reduced, thereby releasing the upwardly pushed-up state of the cover sheet.After the upwardly pushed-up state of the cover layer is released, the inflation of the bag main body is completed by the tether while the distance of the passenger-side wall portion from the gas supply port is restricted.

[0010] Therefore, the passenger seat airbag of the invention can be rapidly deployed and inflated while preventing it from protruding greatly toward the rear of the vehicle at an early stage of inflation.

[0011] Furthermore, the passenger seat airbag of the invention may preferably be configured such that, at the time of full inflation of the airbag, the rear end side of the cover sheet is connected to a portion located in a free space protruding from the tether accommodation portion. In this case, since the cover sheet is arranged such that, at an early stage of inflation of the bag main body, the longitudinal center portion thereof can be curved at a position protruding upward from the accommodation portion, the inflation gas supplied from the gas supply port can be stably deflected in a manner such that it branches laterally to a portion protruding upward from the accommodation portion, thereby making it possible to provide a strong flow control effect. Consequently, the bag main body can be widely deployed in the lateral direction at an early stage of inflation.

[0012] In particular, the passenger seat airbag of the invention may preferably be configured such that, at the time of full inflation of the airbag, the rear end side of the cover sheet is located near the hinge portion serving as a rotation axis when the flap portion covering the folded and housed airbag is opened. This structure can prevent the cover sheet from excessively protruding rearward at an early stage of inflation of the bag main body. Consequently, at an early stage of inflation of the bag main body, the inflation gas can be deflected to flow in the lateral direction while preventing the inflation gas from flowing rearward as much as possible, thereby providing a stronger flow control effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention will become more fully understood from the detailed description given below and the accompanying drawings which are given by way of illustration only and thus are not intended to be limitative of the present invention, and wherein: Fig. 1 is a schematic longitudinal sectional view of a passenger seat airbag device using an airbag according to an embodiment of the invention, showing its vehicle-mounted state, Fig. 2 is a perspective view of the airbag of this embodiment when inflated as a single unit, Fig. 3 a schematic longitudinal sectional view of the airbag of Fig. 2 along its longitudinal direction, Fig. 4 a schematic cross-sectional view of the airbag of Fig. 2 along its transverse direction, Fig. 5 a schematic sectional view along the VV section of Fig. 3 is, Fig. 6 a top view of the airbag of Fig. 2 is, Fig. 7 is a partially enlarged schematic perspective view of a longitudinally arranged tether and a cover layer disposed within the airbag of this embodiment, Fig. 8 is a plan view of a fabric for forming the airbag of this embodiment, Fig. 9 is a schematic longitudinal sectional view of a passenger seat airbag device using the airbag of this embodiment, taken along its lateral direction, to show the state of the airbag at an early stage of inflation, Fig. 10 is a schematic longitudinal sectional view of a passenger seat airbag device using the airbag of this embodiment, taken along its longitudinal direction, to show the state of the airbag at an early stage of inflation, Fig. 11 is a typical view of a passenger seat airbag device to which the airbag of this embodiment is applied, showing the state of the airbag at an early stage of inflation, and Fig. 12 is a schematic longitudinal sectional view of a passenger seat airbag device to which the airbag of this embodiment is applied, taken along the longitudinal direction thereof to show the state of the airbag in the fully inflated state. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of the invention will be described below with reference to the drawings. In this embodiment, a passenger seat airbag (hereinafter referred to simply as an airbag) 15 for use in a passenger seat airbag device M disclosed in Fig. 1. The passenger seat airbag device M is of a top-mounted type which, as shown in Fig. 1, is arranged in front of a passenger seat of a vehicle on the inside of an upper surface 2 of a dashboard 1. In this embodiment, the longitudinal direction, the vertical direction, and the lateral direction correspond to the longitudinal direction, the vertical direction, and the lateral direction of a vehicle V, respectively, unless otherwise specified.

[0015] The passenger seat airbag device M of this embodiment as shown in the Fig. 1 includes a folded airbag 15, a gas generator 8 for supplying an inflation gas to the airbag 15, a case 12 serving as an accommodating portion for accommodating and holding the airbag 15 and the gas generator 8, a holder 9 for mounting the airbag 15 and the gas generator 8 to the case 12, and an airbag cover 6 for covering the folded airbag 15 from above.

[0016] The airbag cover 6 is formed integrally with the instrument panel 1 made of synthetic resin and includes, on the upper surface side of the instrument panel 1, two flap portions 6a and 6a that are pushed open when the airbag 15 is deployed and inflated. The flap portions 6a and 6a are arranged side by side on the longitudinal direction side, and in this embodiment, a tear portion 6b having a substantially H-like shape when viewed from above is arranged in the vicinity thereof. When the airbag 15 is deployed and inflated, the flap portions are pushed by the inflating airbag 15, thereby opening them in the longitudinal direction around a hinge portion 6c arranged on the outer side in the longitudinal direction while the tear portion 6b is torn.Furthermore, the airbag cover 6 comprises connecting wall sections 6d in the vicinity of the flap sections 6a and 6a, which are to be connected to the housing 12.

[0017] The gas generator 8, which is located in the Fig. 1, comprises a substantially cylindrical main body portion 8a having a plurality of gas discharge openings 8b and a collar portion 8c for mounting the gas generator 8 to the housing 12.

[0018] The casing 12 serving as an accommodating portion is a substantially rectangular parallelepiped-shaped sheet metal casing having a rectangular opening at its upper end side, and includes a substantially plate-shaped lower wall portion 12a for inserting the inflator 8 from below and mounting it in the casing, and a peripheral wall portion 12b extending upward from the outer peripheral edge of the lower wall portion 12a for fixing the connecting wall portions 6d of the airbag cover 6.In this embodiment, the airbag 15 and the inflator 8 are passed through the peripheral edge portion 19 of the gas supply port 18 of the airbag 15, the lower wall portion 12a, and the collar portion 8c of the inflator 8, and are fixed by a nut 10 using the bolts 9a of the holder 9 disposed inside the airbag 15 as mounting members, thereby being mounted to the lower wall portion 12a of the case 12. Further, a bracket (not shown) to be connected to the body side of the vehicle V is provided on the lower wall portion 12a of the case 12.

[0019] The airbag 15, which is in the Fig. 2 to 6, comprises a bag main body 16 which can be inflated by supplying inflation gas therein, restraining belts 29, 36 and 37 arranged inside the bag main body 16 for restricting the shape of the bag main body 16 after full inflation, and a cover sheet 40 arranged inside the bag main body 16.

[0020] The airbag main body 16 in this embodiment is, as shown by the two-dot chain line of Fig. 1 and in the Fig. 12, is formed as a substantially bag-shaped member which, when inflation is completed, can be arranged to close the space between the upper surface 2 of the instrument panel 1 and a windshield 4 provided above the instrument panel 1. Specifically, the airbag main body 16 includes a passenger-side wall portion 25 arranged to extend substantially along the vertical direction on the rear end side when inflation is completed, and a peripheral wall portion 17 having a shape extending forward from the outer peripheral edge of the passenger-side wall portion 25 and converging toward the front end side, while the main body, when inflation is completed, has a substantially quadrangular pyramid shape with the front end side of the peripheral wall portion 17 as its uppermost portion.

[0021] The peripheral wall portion 17 is a portion arranged so that, when the inflation of the airbag 15 is completed, the peripheral wall portion 17 predominantly closes the space between the upper surface 2 of the instrument panel 1 and the windshield 4 located above the instrument panel 1. It includes an upper wall portion 17a and a lower wall portion 17b arranged on the upper and lower sides substantially along the lateral direction, and a left wall portion 17c and a right wall portion 17d arranged on the left and right sides substantially along the longitudinal direction.In the vicinity of the front end of the lower wall portion 17b of the peripheral wall portion 17, which provides the vicinity of the front end of the bag main body 16 at the time of full inflation, a gas supply port 18 is formed through which the inflation gas can be supplied into the airbag main body, while the port has a substantially circular shape into which the main portion 8a of the inflator 8 can be inserted. This gas supply port 18 is formed at the substantially lateral central position of the lower wall portion 17b. In the peripheral edge portion 19 of the gas supply port 18 of the lower wall portion 17b, a plurality (four in this embodiment) of mounting holes 20 are formed, through which the screws 9a of the holder 9 for mounting the peripheral edge portion 19 of the gas supply port 18 to the lower wall portion 12a of the casing 12 can be inserted.Further, in the left and right wall portions 17c and 17d of the peripheral wall portion 17, vent holes 22 for discharging excess inflation gas supplied into the bag main body 16 are formed, respectively, each hole being opened substantially in a circular shape.

[0022] The passenger-side wall portion 25 is arranged to face a passenger sitting on the passenger seat at the time of complete inflation of the bag main body 16 and to extend substantially along the vertical direction on the rear end side of the bag main body 16, which provides the passenger side. In this embodiment, the passenger-side wall portion 25 includes a forward recessed recess portion 26 extending substantially along the vertical direction at a position that, when inflation of the airbag main body 16 is completed, provides substantially a center position in the lateral direction (see the Fig. 3 and Fig. 4). This recess portion 26 is arranged in this embodiment so as to extend substantially over the entire vertical areas of the passenger-side wall portion 25. The recess portion 26 of the passenger-side wall portion 25 includes, on its left and right sides, projecting portions 27L and 27R that project relatively rearward. That is, in the passenger-side wall portion 25 of the bag main body 16 of the embodiment, at the time of full inflation of the airbag main body 16, the recess portion 26, which is recessed in the center in the lateral direction, and the projecting portions 27L, 27R to be arranged on the left and right sides of the recess portion 26 sequentially along the vertical direction are arranged ( Fig. 3 and Fig. 4). Specifically, in this embodiment, the projecting state of the projecting portion 27L, 27R and the recessed state of the recessed portion 26 are set substantially identical to each other, while allowing these recessed and projecting shapes to converge forward within the ranges of the upper and lower wall portions 17a and 17b of the peripheral wall portion 17.In the bag main body 16 of this embodiment, the front end of the recessed shape of the recess portion 26 is formed of a sewn portion formed by sewing (joining) the inner peripheral edges 49b and 50b of an inner left panel 49 and an inner right panel 50 (which will be described later) that constitute the passenger-side panel 25, while the projecting uppermost portions of the projecting portions 27L and 27R are formed of sewn portions formed by sewing the rear edges 44e and 45e of an outer left panel 44 and an outer right panel 45 and the outer edges 49a and 50a of the inner left and right panels 49 and 50 (all of these panels will be described later).

[0023] Within the airbag main body 16 in this embodiment, as shown in the Fig. 3 to 5, three retaining belts 29, 36 and 37 are arranged, in particular the longitudinally arranged retaining belt 29 for connecting the vicinity of the gas supply opening 18 to the passenger-side wall section 25 and the two left and right retaining belts 36 and 37 for connecting the left and right wall sections 17c and 17d respectively above and below the longitudinally arranged retaining belt 29.

[0024] In this embodiment, the longitudinally arranged retaining belt 29 is formed such that a front side portion 30 extending from the peripheral edge of the gas supply opening 18 and a rear side portion 34 extending from the passenger-side wall portion 25 are connected to each other.

[0025] The front side section 30 is formed in this embodiment by folding a front side section element part 52 which is shown in the Fig. 8, into a shape which is symmetrical with respect to the center of the gas supply opening 18 as the center, while the outer shape thereof at the time of full inflation of the bag main body 16 has a shape similar to that of a substantially triangular pyramid, with its front end side extending substantially horizontally and its rear end side extending vertically (cf. Fig. 3 to 5). In this embodiment, as shown in the Fig. 3 and Fig. 4, the front end side portion of the front side portion 30 is used as a connecting portion 31 for connecting to the bag main body 16. In this connecting portion 31, openings (not shown) are formed that correspond to the gas supply port 18 and the mounting holes 20, and the entire periphery of the connecting portion 31 is sewn to the lower wall portion 17b in the peripheral edge 19 of the gas supply port 18. Further, such a portion of the front side portion 30 that extends rearward from the rear edge portion 19b of the peripheral edge 19 of the gas supply port 18 forms a main body 32, while the outer shape of this main body 32 provides a shape substantially corresponding to that of a triangular pyramid ( Fig. 7). The vertical width dimension of the rear end 32a of the main body 32 to be sewn to the front end 34a of the back portion 34 is substantially identical to the vertical width dimension of the front end 34a of the back portion 34.

[0026] The back portion 34 has a sheet-like shape and, in this embodiment, includes extension portions 49c and 50c extending from the inner peripheral edges 49b and 50b of the inner left wall surface 49 and the inner right wall surface 50 constituting the passenger-side wall portion 25 of the bag main body 16 and joined to the inner left and right wall surfaces 49 and 50 (see the Fig. 3 and Fig. 4). These extension portions 49c and 50c extend from the areas near the center of the inner peripheral edges 49b and 50b of the inner left and right wall surfaces 49 and 50. In other words, the rear side portion 34 is formed of two laminated sheets, and the sheets are respectively integrated with the inner left and right wall surfaces 49 and 50, whereby the rear end 34b side is connected to the vertically and laterally substantially central area (the front end of the recessed shape of the recess portion 26) of the passenger side wall portion 25.Specifically, in this embodiment, the rear side portion 34 has a substantially trapezoidal shape in which the front end 34a side to be connected to the front side portion 30 has a small width, and the rear end 34b side extends vertically in the direction of the inner peripheral edges 49b and 50b of the inner left and right wall surfaces 49 and 50.

[0027] The left and right tethers 36 and 37 are arranged substantially along the lateral direction so that they can connect the left and right wall portions 17c and 17d to each other at the time of full inflation of the bag main body 16. In this embodiment, as shown in FIGS. Fig. 3 and Fig. 5, arranged in two sections, each above and below the longitudinally arranged tether belt 29. In this embodiment, the upper lateral tether belt 36 arranged above the longitudinally arranged tether belt 29 and the lower lateral tether belt 37 arranged below the longitudinally arranged tether belt 29 are each formed to have a band-like shape extending substantially along the lateral direction, and are arranged to extend substantially along the horizontal direction at the time of full inflation of the bag main body 16 (see the Fig. 3 and Fig. 5). Also in this embodiment, the upper and lower lateral retaining straps 36 and 37, as shown in the Fig. 5, both formed by joining the edges of two tether-forming fabrics 36a, 36b and 37a, 37b arranged side by side in the lateral direction.

[0028] The cover layer 40 is formed of a band-shaped, flexible layer member and is disposed within the bag main body 16 as shown in the Fig. 3 and Fig. 7, is arranged above the gas supply opening 18, while its front end 40a side is connected to the front edge 19a side of the peripheral edge 19 of the gas supply opening 18, and its rear end 40b side is connected to the longitudinally arranged tether 29. The cover layer 40 has a length dimension such that it does not interfere with the restriction of the shape of the bag main body 16 by the longitudinally arranged tether 29 at the time of full inflation, and is formed such that, when the airbag 15 is deployed and inflated, its right and left sides can be opened to cover substantially the entire space above the gas supply opening 18 (see the Fig. 3, Fig. 6 and Fig. 7). In particular, the width dimension H1 of the cover layer 40 is set larger than the inner diameter dimension D1 of the gas supply opening 18 (cf. Fig. 8), and substantially the same as the width dimension of the connecting portion 31 of the front side portion 30 of the longitudinally arranged tether 29, thereby allowing the cover layer 40 to cover substantially the entire space above the gas supply opening 18. Further, substantially the entire side of the front end 40a of the cover layer 40 is sewn to the front edge 19a of the peripheral edge 19 of the gas supply opening 18 using sewing threads, the front edge of the cover layer 40 extending substantially along the lateral direction (see the Fig. 7). Further, substantially the entire side of the rear end 40b of the cover layer 40, which is arranged to extend substantially along the vertical direction, is sewn to the main body 32 of the front side portion 30 of the longitudinally arranged tether 29 using sewing threads, with the cover layer 40 being twisted in the longitudinally arranged central portion (see the Fig. 7). In particular, in this embodiment, the cover layer 40 is formed so that, at the time of full inflation of the bag main body 16, its rear end 40b side is located at a position close to the hinge portion 6c of the airbag cover 6, which serves as the rotation axis of the flap portion 6a, which is arranged on the rear side and slightly recessed immediately above the hinge portion 6c (see the Fig. 12). That is, the rear end side of the cover layer 40 is sewn at a position substantially near the longitudinal center of the left side portion 32b of the main body 32 of the front side portion 30 of the longitudinally arranged tether 29.

[0029] Furthermore, as stated in the Fig. 8, the width dimension of the rear end 40b side of the cover layer 40 is set smaller than the width dimension of the front end 40a side. The cover layer 40 is formed substantially constant in the width direction up to its portion for covering the space above the gas supply opening 18 at an early stage of inflation of the bag main body 16, whereas its portion rearward of the gas supply opening 18 is formed with a reduced width in the direction of the rear end 40b side. The length dimension L1 (cf. Fig. 8) of the cover layer 40 is set so that the cover layer 40 is loosely arranged at the time of full inflation of the bag main body 16 so that no tension is caused between the front and rear ends 40a and 40b (see the Fig. 12) and consequently does not affect the restriction of the shape of the bag main body 16 by the longitudinally arranged tether 29 at the time of full inflation.

[0030] The bag main body 16 is manufactured by joining the peripheral edges of a fabric having a specific shape into a bag shape. In this embodiment, as shown in the Fig. 8, a peripheral wall surface portion 43 predominantly forming the side of the peripheral wall portion 17, and a passenger-side wall surface portion 48 predominantly forming the side of the passenger-side wall portion 25. The peripheral wall portion 43 includes two outer left and right wall surfaces 44 and 45, while the passenger-side wall portion 25 includes a pair of inner left and right wall surfaces 49 and 50.

[0031] The outer left and right wall surfaces 44 and 45 forming the peripheral wall portion 43 are formed to divide the peripheral wall portion 17 into right and left portions, and, as shown in the Fig. 8, they each have a substantially fan-like shape. The outer left wall surface 44 includes a protruding portion 44a forming the peripheral edge of the gas supply opening 18. The outer left wall surface 44 forms the left wall portion 17c, approximately the left front half portion of the upper wall portion 17a, approximately the left half portion of the lower wall portion 17b, and the portion of the passenger-side wall portion 25 located to the left of the protruding uppermost portion of the protruding portion 27L. The outer right wall surface 45 includes a protruding portion 45a forming the peripheral edge of the gas supply opening 18.The outer right wall surface 45 forms the left wall portion 17d, approximately the right front half portion of the upper wall portion 17a, approximately the right half portion of the lower wall portion 17b, and the portion of the passenger-side wall portion 25 that is to the right of the projecting uppermost portion of the projecting portion 27R. The upper edges 44b, 45b and the lower edges 44c, 45c of the outer left and right wall surfaces 44 and 45 are sewn together, thereby forming the peripheral wall portion 17 having a substantially cylindrical shape (see FIG. Fig. 5).

[0032] The inner left and right wall surfaces 49 and 50 form a region between the projecting portions 27L and 27R in the passenger-side wall portion 25. Specifically, the inner left and right wall surfaces 49 and 50 form a region extending from the rear end side region of the upper wall portion 17a of the peripheral wall portion 17 to a region existing between the projecting uppermost regions of the projecting portions 27L and 27R of the passenger-side wall portion 25.They are each approximately crescent-shaped and arranged in pairs with each other such that the upper region at the position of the front end of the recessed portion 26 is divided into a left and a right portion, thereby forming a region extending from the front end of the recessed portion 26 to the projecting uppermost position of the left-side projecting portion 27L and a region extending from the front end of the recessed portion 26 to the projecting uppermost position of the right-side projecting portion 27R (see the . Fig. 8). In this embodiment, on the side of the inner peripheral edges 49b and 50b of the inner left and right wall surfaces 49 and 50, as shown in the Fig. 8, extension portions 49c and 50c are formed, each constituting the rear side portion 34 of the longitudinally arranged tether 29. Further, the inner left and right wall surfaces 49 and 50 are formed such that, when unfolded flat, the outer peripheral edges 49a and 50a extend substantially along the curved shapes of the rear edges 44e and 45e of the outer left and right wall surfaces 44 and 45.

[0033] In this embodiment, the peripheral wall surface portion 43 and the passenger-side wall surface portion 48 constituting the bag main body 16, the front side portion forming member part constituting the longitudinally arranged tether belt 29, and the tether-forming fabrics 36a, 36b, 37a, and 37b constituting the upper lateral tether belt 36 and the lower lateral tether belt 37, respectively, are each formed of flexible fabrics made of polyester yarns, polyamide yarns, or the like.

[0034] Next, the manufacturing of the airbag 15 of this embodiment will be described. The inner left and right wall panels 49 and 50 are superimposed in advance such that their peripheral edges coincide while being flatly deployed, and further, the inner peripheral edges 49b and 50b are sewn together using sewing threads. Further, the one-end sides of the tether-forming fabrics 36a, 36b, 37a, and 37b are sewn to the outer left and right wall panels 44 and 45 in advance. First, the outer left and right wall panels 44 and 45 are superimposed such that their peripheral edges coincide while being flatly deployed, and the lower edges 44c and 45c are sewn together using sewing threads. Further, the outer left and right wall surfaces 44 and 45 are opened such that the projecting portions 44a and 45a overlap with each other.Then, the front-side portion forming member part 52 of the longitudinally arranged tether 29 is placed on the protruding portions 44a and 45a and sewn to the peripheral edge 19 of the gas introduction port 18 using sewing threads, and thereafter, the gas introduction port 18 and the mounting holes 20 are formed by drilling. Next, the front end 40a side of the cover sheet 40 is sewn to the front edge 19a side of the peripheral edge 19 of the gas introduction port 18 using sewing threads. After that, the outer left and right wall surfaces 44 and 45 are superimposed on each other so that their peripheral edges coincide, and the upper edges 44b and 45b are sewn together using sewing threads.Next, the outer left and right panels 44 and 45 are opened such that their rear edges 44e and 45e are separated from each other, the inner left and right panels 49 and 50, which are spread out such that their outer edges 49a and 50a are separated from each other, are superimposed on each other, the rear edge 44e of the outer left panel 44 and the outer peripheral edge 49a of the inner left panel 49 are sewn together using sewing threads, and the rear edge 45e of the outer right panel 45 and the outer peripheral edge 50a of the inner right panel 50 are sewn together, respectively.Then, the main body 32 of the front side portion 30 of the longitudinally arranged tether 29 is folded in half, and the folded rear end 32a side is sewn to the front end 34a side of the rear side portion 34 (the front end sides of the extension portions 49c and 50c of the inner left and right panels 49 and 50), thereby forming the longitudinally arranged tether 29. Furthermore, the corresponding other ends of the tether-forming fabrics 36a, 36b, 37a, and 37b are also joined together, thereby forming the upper and lower lateral tethers 36 and 37. Thereafter, the bag main body 16 is turned inside out using the openings of the front edges 44d and 45d, which are the unstitched portions of the outer left and right wall surfaces 44 and 45, such that the edge of the edge thereof is not exposed to the outside.Next, the front edges 44d and 45d of the outer left and right wall panels 44 and 45 are placed on top of each other while being folded in half, and then sewn together using sewing threads. Next, the rear end 40b of the cover sheet 40 is pulled out from the gas supply port 18 and sewn using sewing threads to the main body 32 of the front side portion 30 of the longitudinally arranged tether 29 that has been pulled out from the gas supply port 18, thereby manufacturing the airbag 15.

[0035] The thus-manufactured airbag 15 with the holder 9 housed therein is folded in such a manner that it can be housed in the casing 12, and the periphery of the folded airbag 15 is wrapped by a tearable wrapping sheet (not shown). Next, the folded airbag 15 is placed on the lower wall portion 12a of the casing 12. The main body portion 8a of the inflator 8 is inserted into the casing 12 from below the lower wall portion 12a, and the bolts 9a projecting downward from the lower wall portion 12a are inserted into the collar portion 8c of the inflator 8. Thereafter, when the nut 10 is screwed onto the bolts 9a projecting from the collar portion 8c of the inflator 8, the folded airbag 15 and the inflator 8 can be mounted on the casing 12.

[0036] When the peripheral wall portion 12b of the housing 12 is fixed to the connecting wall portion 6d of the airbag cover 6 of the instrument panel 1 mounted on the vehicle, and a bracket (not shown) of the housing 12 is fixed to the body side of the vehicle, the passenger seat airbag M can be mounted on the vehicle.

[0037] After the passenger seat airbag M is mounted on the vehicle, upon a frontal collision of the vehicle, when the inflation gas is discharged from the gas discharge ports 8b of the inflator 8, the airbag 15 is inflated due to supply of the inflation gas therein, thereby pushing open the door portions 6a, 6a of the airbag cover 6. Further, the airbag 15 protrudes upward from the case 12 through an opening formed by pushing open the door portions 6a, 6a of the airbag cover 6, and is deployed and inflated while protruding toward the rear of the vehicle, thereby completing its inflation, as shown by the two-dot chain line of Fig. 1 and in the Fig. 12 is shown.

[0038] Since, in the airbag 15 of the passenger seat airbag device of this embodiment, the cover sheet 40 for connecting the front end 40a side to the front edge 19a side of the gas supply port 18 and for connecting the rear end 40b side to the longitudinally arranged tether 29 is formed to be arranged above the gas supply port 18, at an early stage of inflation of the airbag 15, when the inflation gas G is supplied into the airbag through the gas supply port 18, flowing rearward (toward the passenger side wall portion 25) as shown in FIG. Fig. 9, the inflation gas G supplied from the gas supply port 18 is applied to the cover layer 40, and thus its flow direction is deflected in the lateral direction. This can prevent the inflation gas G supplied from the gas supply port 18 from directly flowing toward the passenger-side wall portion 25, and also allows the inflation gas G deflected in the lateral direction to widely expand the bag main body 16 in the lateral direction.

[0039] Therefore, according to the airbag 15 in the passenger side wall portion 25, the left and right side portions (projecting portions 27L and 27R) of the central side recess portion 26 with the longitudinally arranged tether 29 connected thereto can be prevented from projecting largely rearward at an early stage of inflation of the airbag 15. Specifically, according to the airbag 15 of this embodiment, since the passenger-side wall portion 25 is formed such that the recess portion 26 is located on the central side in the lateral direction and the projecting portions 27L and 27R projecting relatively rearward are located on the two sides of the lateral direction of the recess portion 26, as long as the cover sheet 40 is not included, the areas of the projecting portions 27L and 27R largely project rearward at an early stage of inflation of the airbag as shown by the two-dot chain line of Fig. 11. However, according to the airbag 15, since the inflation gas G supplied from the gas supply port 18 is deflected in the lateral direction by the cover layer 40, the areas of the projecting portions 27L and 27R can be prevented from Fig. 11, and they can be inflated so as to be widely deployed in the lateral direction. Furthermore, since the cover sheet 40 is inflated by the inflation gas G flowing back from the gas supply port 18 (toward the passenger-side wall portion 25) as shown in FIG. Fig. 10, the lateral direction center portion 40c is pushed upward by the inflation gas G, so that the cover sheet 40 is curved, thereby pushing the rear end 40b side connected to the longitudinally arranged tether 29 forward. Therefore, the longitudinally arranged tether 29 can be pushed forward by the cover sheet 40, and consequently, at an early stage of inflation of the bag main body 16, the rear end of the longitudinally arranged tether 29 can be prevented from being moved rearward excessively.

[0040] As a result, according to the airbag 15, since at an early stage of inflation of the bag main body 16, the direction of the inflation gas G can be deflected and the rearward movement of the rear end of the longitudinally arranged tether 29 can be prevented by the cover layer 40, the bag main body 16 can be appropriately prevented from unfolding in the lateral direction at an early stage of inflation, and the passenger-side wall portion 25 can also be appropriately prevented from excessively protruding rearward. Furthermore, when the bag main body 16 is inflated and the inflation is almost completed, the flow velocity of the inflation gas G flowing therein is also reduced through the gas supply port 18, thereby canceling the compressed state of the cover layer 40. According to the airbag 15, since the length dimension of the cover layer 40, as shown in the Fig. 12 is set so as not to affect the restriction of the shape of the bag main body 16 at the time of full inflation by the longitudinally arranged tether belt 29, after the pressed-on state of the cover sheet 40 is released, the inflation of the bag main body 16 is completed while its distance from the gas supply port 18 of the passenger-side wall portion 25 is restricted by the longitudinally arranged tether belt 29.

[0041] Therefore, while preventing the strong protrusion toward the rear of the vehicle at an early stage of inflation, the airbag 15 can be quickly deployed and inflated.

[0042] Further, according to the airbag 15, inside the bag main body 16, above and below the longitudinally arranged tether belt 29, as shown in the Fig. 3 and Fig. 5, the upper-side lateral tether 36 and the lower-side lateral tether 37 for connecting the left wall portion 17c and the right wall portion 17d, which are opposite to each other on the lateral direction side of the peripheral wall portion 17, are arranged along the lateral direction. Consequently, when the bag main body 16 is widely expanded in the lateral direction by supplying the inflation gas G that has been deflected in the lateral direction by the cover sheet 40, the bag main body 16 can be prevented from being widely expanded in the lateral direction, and thus the left and right wall portions 17c and 17d can be prevented from excessively separating from each other.Consequently, the bag main body 16 can be prevented from being deployed and inflated with a recoil phenomenon consisting of repeated occurrence of rearward protrusion and lateral expansion, whereby the bag main body 16 can be inflated with limited oscillation. Specifically, according to the airbag 15, since the upper-side lateral tether 36 and the lower-side lateral tether 37 are arranged above and below the longitudinally arranged tether 29 along the longitudinally arranged tether 29, the distance between the left and right wall portions 17c and 17d can be accurately restricted over a wide vertical range.

[0043] Further, according to the airbag 15, since the rear end 40b side of the cover sheet 40, when the inflation of the airbag 15 is completed, is connected to a portion of the longitudinally arranged tether 29 projecting from the case 12 serving as an accommodating portion, the cover sheet 40, as shown in the Fig. 10, at an early stage of inflation of the bag main body 16, the longitudinally arranged central portion 40c is curved at a position projecting upward from the casing 12, whereby the inflation gas G supplied from the gas supply port 18 can be stably deflected to branch laterally into a region (central portion 40c) projecting upward from the casing 12, so that a strong flow control effect is provided, and consequently the bag main body 16 can be laterally widely deployed at an early stage of inflation.

[0044] In particular, according to the airbag 15, the rear end 40b side of the cover sheet 40 is located at a position slightly rearward than immediately above the hinge portion 6c of the opened flap portion 6a of the airbag cover 6 at the time of full inflation of the airbag 15 (see the Fig.12). Consequently, since the cover sheet 40 can be prevented from projecting excessively rearward at an early stage of inflation of the bag main body 16, the rearward flow of the inflation gas G can be prevented as much as possible at an early stage of inflation of the bag main body 16, and consequently, the inflation gas G can be deflected to flow in the lateral direction, thereby providing an even stronger flow control effect. Meanwhile, as long as these aspects are considered, the length dimension of the cover sheet can be increased, and the rear end side can also be formed to be connected to, for example, the rear portion of the longitudinally arranged tether.

[0045] In this embodiment, the airbag 15 has a structure in which the laterally central side of the passenger-side wall portion 25 is recessed and its two sides protrude in the lateral direction, so that the recess portion 26 and the protruding portions 27L and 27R are provided. However, the airbag to which the invention can be applied is not limited to the embodiment, and the invention can also be applied to an airbag configured such that a passenger-side wall portion has neither a recess nor a protruding part, but is formed flat upon completion of inflation of the airbag.

[0046] It is explicitly emphasized that all features disclosed in the description and / or the claims are to be considered separate and independent of each other for the purpose of the original disclosure as well as for the purpose of limiting the claimed invention, regardless of the feature combinations in the embodiments and / or the claims. It is explicitly stated that all range specifications or specifications of groups of units disclose every possible intermediate value or subgroup of units for the purpose of the original disclosure as well as for the purpose of limiting the claimed invention, in particular also as a limit of a range specification.

Claims

[1] Passenger seat airbag, comprehensive a bag main body (16) configured to be folded and accommodated in an accommodation portion (12) formed in a dashboard disposed in front of the passenger seat of a vehicle, and which, when an inflation gas is supplied therein, can be inflated so as to protrude toward the rear of the vehicle, and a holding belt (29) arranged within the bag main body (16) and configured to restrict the shape of the bag main body (16) at the time of its full inflation, wherein the bag main body (16) includes a passenger-side wall portion (25) arranged to be located substantially along the vertical direction on the rear end side of the bag main body (16) at the time of full inflation, and a peripheral wall portion (17) shaped to extend forward from the outer peripheral edge of the passenger-side wall portion (25) and converge toward the front end of the bag main body (16), the peripheral wall portion (17) including, on the front lower surface side thereof, a gas supply opening (18) opened to allow inflation gas to flow therethrough and having a peripheral edge mounted on the side of the accommodation portion (12), and the retaining strap (29) with the rear edge side (19b) of the gas supply opening (18) and extends rearwardly therefrom, and at the time of full inflation, a rear end side thereof is connected to the vicinity of the center of the passenger-side wall portion (25), thereby limiting the distance of the passenger-side wall portion (25) from the gas supply opening (18) at the time of full inflation of the bag main body (16), characterized by , that a cover layer (40) formed of a band-shaped flexible layer member and arranged above the gas supply opening (18) is provided, the front end side (40a) of the cover layer (40) being connected to the front edge side (19a) of the gas supply opening (18) and the rear end side (40b) of which is connected to the tether (29) so that the inflation gas is deflected in the lateral direction and the inflation gas is prevented from flowing directly toward the passenger-side wall portion (25). [2] A passenger seat airbag according to claim 1, wherein the rear end side (40b) of the cover sheet (40) is connected to a portion located in a free space projecting from the accommodating portion (12) at the time of full inflation of the airbag. [3] A passenger seat airbag according to claim 2, wherein the cover sheet (40) is formed so that, at the time of full inflation of the airbag, its rear end (40b) side is located near a hinge portion (6c) serving as a rotation axis when a door portion (6a) covering the folded and housed airbag is opened.

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