JP2013049326A - Steering wheel airbag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple steering wheel airbag that prevents a driver from being unnecessarily pressed during inflation.SOLUTION: The airbag 20 is formed in substantially a disk shape so that the thickness of a rear region is smaller than that of a front region when completely inflated. The airbag includes a vehicle body-side wall 21 arranged on the side of a steering wheel and an occupant-side wall 26 arranged on the side of a driver, and has a bag shape formed by joining the rims of the vehicle-side wall 21 and the occupant side-wall 26 with a rim joining part 28. In the rim joining part 28, when the airbag 20 is developed flat so as to make the rear region 20b thinner than the front region 20a when completely inflated, a concave joining part 30 is arranged inside a circular arc C continuous from nearby substantially circular-arc general joining part 29, in a portion of a region located in the rear of the front/back center. The concave joining parts 30 are arranged symmetrically on both sides.

Description

  The present invention relates to an airbag for a steering wheel in which an expansion completion shape is a substantially disk shape that can cover the entire upper surface of a steering wheel.

  Since the steering wheel equipped with the steering wheel airbag is inclined with respect to the driver's upper body, the distance between the steering wheel and the driver's abdomen is the steering wheel and the driver's head. It is small compared with the separation distance. Therefore, when the inflating thickness of the steering wheel airbag is made uniform in the front and back, and the steering wheel airbag is inflated thickly so that the driver's head can be softly protected with good cushioning, The driver tries to move forward so that the entire airbag is displaced from the driver when the rear region of the airbag on the way comes into contact with the parts from the chest to the abdomen of the driver and strongly presses these parts. In some cases, the head of the head was unnecessarily pressed upward.

  Therefore, in order to prevent the region on the rear side of the airbag in the middle of inflation from strongly pressing the region from the chest to the abdomen of the driver, as a steering wheel airbag, the rear side of the airbag approaching the driver's abdomen There is a configuration in which the region is expanded so as to be thinner than the front region (see, for example, Patent Documents 1 and 2).

  In the steering wheel airbag described in Patent Document 1, a tether that regulates the separation distance between the vehicle body side wall portion and the occupant side wall portion at the time of completion of inflation is arranged inside the airbag, and the shape of the airbag after inflation is rearranged. The side area was regulated to be thinner than the front area.

  Further, in the steering wheel airbag described in Patent Document 2, the inflation completion shape is a non-circular, substantially rectangular shape, and a tack is provided in the region on the front edge side when the inflation is completed to thicken the front region. When the expansion is completed, the left and right centers on the rear edge side at the completion of the expansion are provided with recesses to make the rear region thinner than the front region.

Japanese Patent Laid-Open No. 9-30353 JP 2008-49834 A

  However, in the steering wheel airbag described in Patent Document 1, it is necessary to couple the tether that regulates the inflation completion shape of the airbag to the airbag over a wide range in the front and rear in the airbag. It was not convenient.

  Further, the steering wheel airbag described in Patent Document 2 also has a simple configuration because the thickness at the completion of the expansion of the front region is secured by providing a tack on the peripheral wall and joining the peripheral edges. It wasn't.

  SUMMARY OF THE INVENTION The present invention solves the above-described problems, and an object of the present invention is to provide a steering wheel airbag that can suppress unnecessary pressing of the driver during inflation as a simple configuration.

The airbag for a steering wheel according to the present invention has an inflated shape that can cover the upper surface of the steering wheel over substantially the entire surface, and the thickness of the rear region is set to be thinner than that of the front region. As a disk,
The vehicle body side wall portion disposed on the steering wheel side upon completion of expansion and the occupant side wall portion disposed on the driver side upon completion of expansion, and having a substantially circular shape with the same outer shape, and the vehicle body side wall portion and occupant side wall An airbag for a steering wheel configured in a bag shape by combining peripheral edges with a portion,
Flatten the airbag so that the peripheral coupling part that joins the peripheral edges of the vehicle body side wall part and the passenger side wall part can reduce the thickness of the rear side area of the airbag when the inflation is completed to be thinner than the front side area. In the unfolded state, a concave coupling portion located inside a circular arc continuous from the surrounding general arc-shaped general coupling portion is arranged in a part of the area behind the front and rear centers, and the concave coupling portion is bilaterally symmetrical It is characterized by being arranged.

  The airbag for a steering wheel of the present invention has a concave coupling portion in which the peripheral edges of the vehicle body side wall portion and the occupant side wall portion are recessed inward at a position in which the part of the rear region from the front and rear center is symmetrical. If combined so as to form a peripheral edge connecting portion, the thickness of the rear region at the time of completion of inflation can be made thinner than the thickness of the front region. Is simple and can reduce the number of manufacturing steps and cost. Of course, in the airbag for a steering wheel according to the present invention, the rear region adjacent to the driver's abdomen is inflated thinner than the front region. It is possible to suppress the region from strongly pressing the region from the chest to the abdomen of the driver, and it is possible to accurately prevent the airbag from unnecessarily pressing the driver's head rearward and upward during inflation.

  Therefore, in the steering wheel airbag according to the present invention, it is possible to suppress the driver from being unnecessarily pressed during inflation as a simple configuration.

  Further, in the steering wheel airbag according to the present invention, when the recessed coupling portion is formed in a region excluding the rear edge side in a state where the airbag is flatly deployed, when the airbag is completely inflated, An expansion part can be arranged between the ring part of the steering wheel, and the abdomen of the driver can be accurately protected by this expansion part, which is preferable.

  Further, in the steering wheel airbag according to the present invention, if the recess coupling portion is set to a size that allows the ring portion of the steering wheel to be covered from the driver side by the airbag that has been completely inflated, the inflation is achieved. When the driver is restrained by the airbag at completion, the periphery of the airbag can be supported by the ring part of the steering wheel over the entire circumference, so the driver is restrained accurately by the reaction force from the ring part. This is preferable.

  Furthermore, in the steering wheel airbag according to the present invention, if the vehicle body side wall portion and the occupant side wall portion are connected to each other only by the peripheral edge coupling portion, the vehicle body side wall portion and the occupant side wall are provided inside the airbag. Since a member such as a tether that connects the parts is not arranged, the airbag is inflated without regulating its thickness at the initial stage of inflation, so that the driver can easily come into contact with the driver. This is preferable because it can be received quickly.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view showing a steering wheel airbag device using an airbag according to an embodiment of the present invention. It is a schematic longitudinal cross-sectional view at the time of vehicle mounting in the airbag apparatus of FIG. 1, and has shown the airbag at the time of completion of inflation with the dashed-two dotted line. It is a bottom view of the state which developed the air bag used for the air bag device of Drawing 1 flat. FIG. 4 is a bottom view of a state in which the airbag of FIG. 3 is inverted and flattened so as to expose a peripheral joint portion. It is a top view which shows the cloth material which comprises the airbag of FIG. It is a top view which shows the state which the airbag completed the expansion | swelling in the airbag apparatus of embodiment. In the airbag apparatus of embodiment, it is a side view which shows the state which the airbag completed inflation. It is a bottom view of the state which developed the air bag of other forms of the present invention flatly. FIG. 9 is a bottom view of the airbag of FIG. 8 in a state where the airbag is inverted and flattened so as to expose the peripheral joint portion. FIG. 9 is a plan view showing a state in which the airbag is completely inflated in the airbag device using the airbag of FIG. 8. It is a side view which shows the state which the airbag completed the expansion | swelling in the airbag apparatus using the airbag of FIG. It is a bottom view of the state which developed the air bag of other forms of the present invention flatly. FIG. 13 is a bottom view of a state where the airbag of FIG. 12 is inverted and flattened so as to expose the peripheral joint portion. FIG. 13 is a plan view showing a state in which the airbag is completely inflated in the airbag device using the airbag of FIG. 12. FIG. 13 is a side view showing a state in which the airbag is completely inflated in the airbag device using the airbag of FIG. 12.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The steering wheel airbag (hereinafter simply referred to as “airbag”) 20 of the embodiment is used in an airbag apparatus M for a steering wheel W as shown in FIGS.

  It should be noted that the front-rear, up-down, left-right directions in the embodiment are based on the straight-ahead steering of the steering wheel W mounted on the vehicle unless otherwise specified, and the steering shaft SS (see FIG. 2), the vertical direction is the vertical direction, the longitudinal direction of the vehicle that is orthogonal to the steering shaft SS is the longitudinal direction, and the lateral direction of the vehicle that is orthogonal to the steering shaft SS is the lateral direction.・ It indicates the vertical and horizontal directions.

  As shown in FIGS. 1 and 2, the steering wheel W includes a steering wheel main body 1 and an airbag device M disposed on the upper portion of the boss B at the center of the steering wheel main body 1 in the embodiment. It is configured. The steering wheel body 1 includes an annular ring portion R that is gripped at the time of steering, a boss portion B that is disposed substantially at the center of the ring portion R and connected to the steering shaft SS, and connects the boss portion B and the ring portion R. And a plurality of (four in the case of the embodiment) spoke portions S.

  As shown in FIG. 2, the steering wheel main body 1 is arranged so as to connect the ring part R, the boss part B, and the spoke part S, and includes a metal core 2 made of a metal such as an aluminum alloy. Has been. A synthetic resin coating layer 5 is coated on a portion of the ring portion R in the core metal 2 and a portion of each spoke portion S on the ring portion R side. A steel boss 3 for inserting the steering shaft SS and fixing the nut N is disposed at a portion of the boss portion B of the core metal 2. Further, a lower cover 7 made of a synthetic resin that covers the lower portion of the boss portion B is disposed at the lower portion of the steering wheel body 1.

  As shown in FIGS. 1 and 2, the airbag apparatus M according to the embodiment is disposed in a boss portion B at the center of the steering wheel W, and is folded and accommodated, and the airbag 20 is inflated. An inflator 10 that supplies a working gas, a case 11 that stores and holds the airbag 20 and the inflator 10, an airbag cover 15 that covers the folded airbag 20, and the airbag 20 and the inflator 10. And a retainer 9 to be attached to the case 11.

  The retainer 9 is formed as a quadrangular ring in which the cylindrical main body portion 10a of the inflator 10 can be inserted from below, and includes bolts (not shown) protruding downward at the four corners. The retainer 9 is housed in the airbag 20 with a bolt (not shown) protruding from a mounting hole 23 (to be described later) of the airbag 20, and each bolt is connected to the bottom wall of the case 11 when attached to the case 11. The airbag 20 and the inflator 10 are attached and fixed to the case 11 by protruding from the flange portion 10c of the inflator 10 through the portion 12 and fastening with nuts.

  The inflator 10 includes a substantially cylindrical main body portion 10a in which a gas discharge port 10b for discharging an inflation gas is disposed at an upper portion, and a substantially square plate-like flange portion 10c disposed so as to protrude from the outer peripheral surface of the main body portion 10a. And. A through-hole (not shown) through which a bolt (not shown) of the retainer 9 passes is formed in the flange portion 10c.

  As shown in FIG. 2, the case 11 is made of a sheet metal and includes a rectangular plate-like bottom wall portion 12 and a side wall portion 13 extending vertically from the outer peripheral edge of the bottom wall portion 12. As shown in FIGS. 1 and 2, the bottom wall portion 12 is formed with an insertion hole 12 a that is circularly opened so that the main body portion 10 a of the inflator 10 can be inserted from below, and the retainer 9 is not shown around the hole 12 a. Four through-holes 12b for penetrating the bolts are formed (see FIG. 1). A mounting piece 13a extending outward is formed on the upper end of the side wall 13 (see FIG. 1), and a mounting board for a horn switch mechanism (not shown) is mounted on the mounting piece 13a. In the case of the embodiment, the case 11 is attached and fixed to the cored bar 2 of the steering wheel W using the mounting board (not shown), and the airbag device M is moved to the steering wheel main body 1 that is already attached to the steering shaft SS. It will be mounted on the upper part of the boss B. Further, the side wall 17 of the airbag cover 15 is attached to the side wall 13 of the case 11 using a rivet 18 or the like (see FIG. 2).

  The airbag cover 15 is made of synthetic resin, and includes a ceiling wall portion 16 that covers the upper portion of the airbag 20 housed in the case 11, and a substantially rectangular tubular side wall portion 17 that extends downward from the vicinity of the outer peripheral edge of the ceiling wall portion 16. And is configured. The ceiling wall portion 16 is formed with two door portions 16a that are pushed by the inflating airbag 20 and open forward and backward.

  As shown by the two-dot chain line in FIGS. 1 and 2, the airbag 20 is configured as a substantially disk shape that covers the upper surface of the steering wheel W over substantially the entire surface.

  The airbag 20 is formed of a flexible sheet material, and is configured as a bag shape that can be inflated by allowing an inflation gas to flow therein. In the case of the embodiment, a polyamide yarn, a polyester yarn, or the like It is formed from the flexible woven fabric which consists of. In the embodiment, the airbag 20 has the same substantially circular outer shape, and the vehicle body side wall portion 21 disposed on the steering wheel W side when the inflation is completed, and the passenger side wall portion 26 disposed on the driver side when the inflation is completed. And the periphery 21a of the vehicle body side wall 21 and the occupant side wall 26 are sewn (coupled) at the periphery coupling portion 28 to form a bag shape ( (See FIGS. 3 and 4). In the case of the embodiment, the vehicle body side wall portion 21 and the occupant side wall portion 26 are positions behind the front and rear centers, and the left and right sides excluding the rear edge side are notched so that the second half region is formed. Compared to the semicircular front half region, the width dimension in the left-right direction is narrowed.

  As shown in FIG. 3, the main body 10 a of the inflator 10 is inserted from below into the center of the vehicle body side wall 21, and the inflation gas discharged from the gas discharge port 10 b of the inflator 10 is placed in the airbag 20. An inflow opening 22 for inflow is formed in a circular shape. Further, four attachment holes 23 for inserting bolts (not shown) formed in the retainer 9 are formed in the periphery of the inflow opening 22 in the vehicle body side wall 21. Further, in the vehicle body side wall portion 21, vent holes 24 for exhausting excess inflation gas that has flowed into the airbag 20 are formed in two symmetrical areas in a region in front of the inflow opening 22. Has been.

  As shown in FIG. 4, the peripheral edge coupling portion 28 that couples the peripheral edges 21 a and 26 a of the vehicle body side wall portion 21 and the occupant side wall portion 26 with each other is connected to the peripheral edges 21 a and 26 a of the vehicle body side wall portion 21 and the occupant side wall portion 26. It is formed by sewing over the entire circumference using a suture thread, and includes an arc-shaped general coupling portion 29 and a concave coupling portion 30 located on the inner side of the arc C continuous from the general coupling portion 29. Yes. The dent coupling part 30 is a part of a region behind the front and rear centers of the airbag 20 and is arranged to be symmetrical in a region excluding the rear edge side. The general coupling portion 29 includes a front side portion 29 a disposed on the front side of each concave coupling portion 30 and a rear side portion 29 b disposed on the rear side of each concave coupling portion 30.

  Specifically, in the case of the embodiment, each recess coupling portion 30 is formed so as to linearly connect both ends of the arc of the sector F1 with the central angle θ1 set to 50 ° as shown in FIG. Has been. That is, each dent coupling part 30 is composed of a string in the area of the sector F1 that constitutes a part of the peripheral coupling part 28. In addition, the sector F1 that constitutes each of the recess coupling portions 30 has a crossing angle α1 between the front edge Ff and the line L1 along the left-right direction passing through the center of the peripheral edge coupling portion 28 set to 25 °, and the trailing edge The crossing angle β1 between Fb and the line L2 along the front-rear direction passing through the center of the peripheral joint portion 28 is arranged at a position where it is set to 15 °. That is, in the peripheral joint portion 28 in the airbag 20 of the embodiment, the rear portion 29b in the general joint portion 29 is configured by a sector F2 arc having a central angle set to 2 × β1 = 30 °. The front portion 29a in the portion 29 is configured by an arc of a sector F3 having a central angle set to 180 + 2 × α1 = 230 °.

  The arrangement position and arrangement area (length, depression amount) of each depression coupling portion 30 are set to dimensions that can make the rear area 20b thinner than the front area 20a when the airbag 20 is completely inflated. Has been. Further, in the case of the embodiment, the length of each recess coupling portion 30 (the width in the circumferential direction) and the amount of recess from the arc C connected to the general coupling portion 29 cause the inflation when the airbag 20 is completely inflated. The size of the ring portion R of the steering wheel W that can be covered with the completed airbag 20 when viewed from the driver side, in other words, the ring portion R of the steering wheel W is exposed when the airbag 20 is completely inflated. Instead, the air bag 20 is set to a dimension that allows the ring portion R to be covered over the entire surface.

  In the airbag 20 of the embodiment, the vehicle body side wall portion 21 and the occupant side wall portion 26 are configured such that only the peripheral edges 21 a and 26 a are connected to each other by the peripheral edge coupling portion 28. In addition, the recessed coupling portions 30 and 30 in the peripheral coupling portion 28 are formed in a straight line shape in a state where the airbag 20 is flatly deployed. However, the airbag 20 is formed on the vehicle body side wall portion 21 and the occupant side wall portion 26. Since the centers are inflated so as to be largely separated from each other, when the airbag 20 is completely inflated, the region of the recessed coupling portions 30 and 30 is curved and arranged so that the center is directed inward (see FIG. 6).

  As shown in FIG. 5, the airbag 20 of the embodiment includes a vehicle body side base fabric 33 that forms the vehicle body side wall portion 21, an occupant side base fabric 34 that forms the occupant side wall portion 26, and an inflow in the vehicle body side wall portion 21. And a substantially annular reinforcing cloth 35 that reinforces the periphery of the opening 22. In the case of the embodiment, the vehicle body side base fabric 33 and the occupant side base fabric 34 have the outer shape substantially matched with the outer shape of the peripheral edge coupling portion 28 so that the portion corresponding to the concave coupling portion 30 is partially recessed. It is a simple shape. In addition, as an airbag, you may use what formed the vehicle body side base fabric and the passenger | crew side base fabric into a substantially circular shape, and indented only the periphery coupling | bond part.

  The airbag 20 of the embodiment has a vehicle body side base fabric 33 (vehicle body side wall portion 21) and a passenger side base fabric 34 (passenger side wall portion 26) in a state in which a reinforcing cloth 35 is sewn in advance, and an outer peripheral surface. In a state of being flattened while facing each other, the peripheral edges 21a and 26a are overlapped so as to coincide with each other, and the peripheral edges are sewn together using a suture so as to form the peripheral edge connecting portion 28. Can be manufactured by using the inflow opening 22 so as not to be exposed to the outside.

  When the airbag 20 of the embodiment is mounted on a vehicle, the retainer 9 is inserted into the airbag 20 so that a bolt (not shown) of the retainer 9 protrudes from the mounting hole 23 of the airbag 20. The bag 20 is folded and wrapped around the folded airbag 20 with a predetermined folding preventing material so as not to collapse. Next, the airbag 20 is housed on the bottom wall portion 12 of the case 11 so that each bolt of the retainer 9 protrudes from the through hole 12b. Further, the main body portion 10a of the inflator 10 is moved from below to the bottom wall portion 12 of the bottom wall portion 12. The air bag 20 and the inflator 10 can be attached to the case 11 by inserting the bolts of the retainer 9 through the insertion holes 12a, passing the bolts of the retainer 9 through the flange portions 10c, and fastening them with nuts. Further, by covering the case 11 with the airbag cover 15 and connecting the side wall portions 13 and 17 using the rivets 18 and the like, the airbag cover 15 is attached to the case 11, and the attachment piece 13 a of the case 11 is further attached. If the horn switch mechanism (not shown) is assembled, the airbag device M can be assembled. The airbag device M can be mounted on a vehicle if it is attached to the steering wheel body 1 that has been fastened to the steering shaft SS in advance using an attachment board (not shown) of the horn switch mechanism.

  If the traveling vehicle collides after the airbag device M is mounted on the vehicle, the inflator 10 operates so as to discharge the inflation gas from the gas discharge port 10b, and the airbag 20 causes the inflation gas to be discharged. The door 16a formed in the airbag cover 15 is inflated by flowing into the interior, pushes open the door 16a, protrudes from the case 11, and as shown in FIGS. Expansion is completed so as to cover the entire upper surface side of the entire surface.

  In the airbag 20 of the embodiment, the peripheral edges 21a and 26a of the vehicle body side wall portion 21 and the occupant side wall portion 26 are recessed inward at a position where the part of the rear region from the front and rear center is symmetrical. If they are joined so as to form the peripheral joint 28 having the recessed joints 30, 30, the thickness of the rear region 20 b at the time of completion of expansion is greater than the thickness of the front region 20 a as shown in FIG. Since the thickness can be reduced, the configuration is simpler than that of a conventional steering wheel airbag, and the number of manufacturing steps and costs can be reduced. Of course, in the airbag 20 of the embodiment, the rear region 20b close to the driver's abdomen is inflated thinner than the front region 20a, so the rear region 20b of the airbag 20 in the middle of inflation. However, it is possible to prevent the airbag 20 from strongly pressing the region from the chest to the abdomen, and to prevent the airbag 20 from unnecessarily pressing the driver's head rearward and upward during inflation.

  Therefore, in the airbag 20 of embodiment, it can suppress that a driver | operator is unnecessarily pressed in the middle of inflation as a simple structure.

  In the airbag 20 of the embodiment, the rear portion 29 b of the general joint portion 29 is disposed between the concave joint portions 30 and 30. That is, in the airbag 20 of the embodiment, the recess coupling portion 30 is formed in a region excluding the rear edge side in a state where the airbag 20 is flatly deployed. Therefore, when the airbag 20 is completely inflated, an inflated portion 20c including a region around the rear portion 29b can be disposed between the driver's abdomen and the ring portion R of the steering wheel W. The driver's abdomen can be accurately protected by the expansion portion 20c. Of course, if this point is not taken into consideration, the recess coupling portions may be arranged so as to be connected to each other on the rear edge side of the airbag. In order to accurately protect the driver's abdomen with the inflated portion 20c, it is desirable that the left and right width dimensions of the rear portion 29b be set to 100 mm or more in a state where the airbag 20 is flatly deployed. In the airbag 20 of the embodiment, the left and right width dimension H1 (see FIG. 4) of the rear portion 29b is set to about 110 mm.

  Furthermore, in the airbag 20 of the embodiment, the recess coupling portions 30 and 30 are set to a size that allows the ring portion R of the steering wheel W to be covered when viewed from the driver side by the airbag 10 that has been inflated. Thus, the airbag 20 covers the entire ring portion R of the steering wheel W when the inflation is completed. Therefore, when the driver is restrained by the airbag 20 when the inflation is completed, the peripheral edge of the airbag 20 can be supported by the ring portion R of the steering wheel W over the entire periphery. Thus, the driver can be restrained accurately. If this point is not taken into account, the ring portion R is slightly exposed in the region of the recess coupling portion 30B when the inflation of the airbag 20B is completed, as in an airbag 20B shown in FIGS. In this way, the recess coupling portion 30B may be formed.

  Furthermore, in the airbag 20 of the embodiment, the vehicle body side wall portion 21 and the occupant side wall portion 26 are connected to each other only by the peripheral edge coupling portion 28, and the vehicle body side wall portion 21 and the occupant are inside the airbag 20. A member such as a tether that connects the side wall portion 26 is not disposed. Therefore, in the airbag 20 of the embodiment, at the initial stage of inflation, the airbag 20 is inflated without regulating the thickness, and is easily in contact with the driver, and the airbag 20 quickly receives the driver. It becomes possible. Of course, if such a point is not taken into consideration, the vehicle body side wall and the occupant side wall are connected to the inside of the airbag, and the thickness when the inflation is completed (separation distance between the occupant side wall and the body side wall) is determined. You may arrange | position the tether for the thickness regulation to regulate. Moreover, it is good also as a structure which provides suitably a tether which suppresses the excessive protrusion to the upper direction of the passenger | crew side wall part of the initial stage of inflation as an airbag.

  In the case of the airbag A that has the same outer diameter as the airbag 20 of the embodiment, does not include the circular coupling recess, and has no tether disposed therein, the airbag A is As shown by the two-dot chain line in FIG. 7, the distance from the ring portion of the occupant side wall portion is increased, and the entire center is expanded into a substantially lens shape with a bulky shape so as to be expanded thickly. When such an airbag is used, when the rear region of the airbag in the middle of inflation comes into contact with the region from the chest to the abdomen of the driver, the passenger side wall is strongly pressed from the chest to the abdomen. The part moves forward so as to deviate from the driver, and the driver's head is strongly pushed rearward and upward so as to push up the chin. On the other hand, in the airbag 20 of the embodiment, even if the tether is not disposed inside, the peripheral edges 21a and 26a of the vehicle body side wall portion 21 and the occupant side wall portion 26 are part of the region behind the front and rear centers. The rear region 20b close to the abdomen of the driver is compared with the front region 20a by connecting the peripheral portion 28 with the peripheral connection portion 28 having the concave connection portions 30 and 30 that are recessed inward at a position that is symmetric. Since the structure is inflated thinly, the rear region 20b of the airbag 20 in the middle of inflation can be prevented from strongly pressing the portion from the chest to the abdomen of the driver, and the thickness is not regulated by the tether during inflation. Therefore, the driver can be quickly received during the expansion.

  In the airbag 20 of the embodiment, the arrangement position and the arrangement area (length and the amount of depression) of the dent coupling part 30 can be changed as appropriate, and the arrangement position and the arrangement area of the dent coupling part 30 can be changed. The inflation completion shape of the airbag 20 can be changed as appropriate.

  In the airbag 20 of the embodiment, the recess coupling portion 30 is arranged in a region about 1/3 of the rear side of the airbag 20 that is flatly deployed. When the airbag 20 is completely inflated, the occupant side wall portion 26 is With respect to the ring surface of the ring portion R, it is disposed so as to be inclined downwardly from the front and back in the vicinity of the center (see FIG. 7).

  On the other hand, for example, in the airbag 20A shown in FIGS. 8 to 11, the recess coupling portions 30A and 30A are arranged in a region in front of the recess coupling portions 30 and 30 in the airbag 20 described above, It is formed so as to extend rearward from the line L1 along the left-right direction passing through the center of the portion 28A. Specifically, in the airbags 20A and 20A, the recessed coupling portions 30A and 30A position the front edge Ff on a line L1 along the left-right direction passing through the center of the peripheral coupling portion 28A, as shown in FIG. In this way, both ends of the arc of the sector F4 having the central angle θ2 set to 65 ° are linearly connected. That is, each recess coupling portion 30A is composed of strings in the area of the sector F4 that constitutes a part of the peripheral coupling portion 28A, and the length dimension (width dimension on the circumferential direction side) is also the above-described airbag 20. It is set to be larger than the recess coupling portion 30 in FIG. Further, the sector F4 constituting each of the recess coupling portions 30A is positioned such that the intersection angle β2 between the rear edge Fb and the line L2 along the front-rear direction passing through the center of the peripheral coupling portion 28A is set to 25 °. Is arranged. That is, in the peripheral joint portion 28A in the airbag 20A, the rear portion 29b in the general joint portion 29A is configured by a sector F5 arc whose center angle is set to 2 × β2 = 50 °. 20 is wider to the left and right than the rear portion 29b. The front side portion 29a in the general coupling portion 29A is composed of a sector F6 arc whose central angle is set to 180 °.

  In the airbag 20A provided with such a recessed coupling portion 30A, the recessed coupling portion 30A is located in front of the recessed coupling portion 30 in the airbag 20, and therefore, in the airbag 20A at the completion of the inflation, the occupant The starting end of the inclination of the side wall portion 26 </ b> A with respect to the ring surface is shifted forward as compared with the airbag 20. Specifically, in the airbag 20A, the occupant side wall portion 26A is inclined rearward and downward with respect to the ring surface of the ring portion R, starting from the front portion of the front and rear centers. Further, in the airbag 20A, since the length (left and right width dimensions) of the rear portion 29b in the general coupling portion 29A is larger than the rear portion 29b in the airbag 20, the rear end side inflation at the completion of the inflation is performed. The region 20 c can be inflated thicker than the airbag 20. Therefore, in the airbag 20A, the inclination of the rear side region 20b with respect to the ring surface of the occupant side wall portion 26A at the time of completion of the inflation is wider than the front and rear compared to the inclination of the occupant side wall portion 26 with respect to the ring surface of the airbag 20. , Can be gentle.

  Moreover, in the airbag 20B shown in FIGS. 12-15, the arrangement position of the dent coupling part 30B is the same as the arrangement position of the dent coupling part 30A in the airbag 20A, and the inward dent amount is larger than that of the dent coupling part 30A. It is getting bigger. Specifically, the recess coupling portions 30B and 30B are formed as a substantially arc shape recessed inward so that the arc C continuous from the general expansion portion 29B is reversed by a straight line connecting both ends (see FIG. 13). ). In the airbag 20B provided with such a recess coupling portion 30B, since the recess amount of the recess coupling portion 30B is larger than that of the recess coupling portion 30A, as shown in FIG. The starting end of the inclination of the occupant side wall portion 26B in the rear region 20b with respect to the ring surface is further shifted forward as compared with the airbag 20A, and the inclination amount of the occupant side wall portion 26B is also the occupant side wall in the airbag 20A. It becomes larger than the inclination with respect to the ring surface of the part 26A. Further, the inflated portion 20c on the rear end side when the inflation is completed is also thinner than the airbag 20A. In the airbag 20B, as shown in FIG. 14, when the inflation is completed, the ring portion R is slightly exposed in the region of the recess coupling portion 30B as viewed from the driver side. The amount of exposure is small, and the surrounding portion can be sufficiently supported by the ring portion R. Therefore, when the driver is restrained by the airbag 20 at the completion of the inflation, the reaction force from the ring portion R The driver can be restrained without hindrance.

20, 20A, 20B ... airbag (steering wheel airbag),
20a ... front region,
20b ... rear region,
21 ... the side wall of the vehicle body,
21a ... peripheral edge,
26, 26A, 26B ... occupant side wall,
26a ... periphery,
28, 28A, 28B ... peripheral joint,
29, 29A, 29B ... general joints,
30, 30A, 30B ... dent coupling part,
R ... Ring part,
W ... Steering wheel,
M: Airbag device.

Claims (4)

The expansion completion shape is a substantially disk shape that can cover the entire upper surface of the steering wheel, and the thickness of the rear region is set to be thinner than the front region,
The vehicle body side wall portion disposed on the steering wheel side when the expansion is completed and the passenger side wall portion disposed on the driver side when the expansion is completed, and the vehicle body side wall portion and the A steering wheel airbag configured in a bag shape by combining peripheral edges with an occupant side wall,
The peripheral coupling portion that couples the peripheral edges of the vehicle body side wall portion and the occupant side wall portion so that the thickness of the rear side region of the airbag at the time of completion of inflation can be made thinner than the front side region. In a state where the bag is flatly deployed, a concave coupling portion located inside a circular arc connected to a general arc-shaped general coupling portion around the surrounding is arranged in a part of a region behind the front and rear centers, and the concave coupling is performed. An airbag for a steering wheel, characterized in that the portions are arranged symmetrically.   2. The steering wheel airbag according to claim 1, wherein the recess coupling portion is formed in a region excluding a rear edge side in a state where the airbag is flatly deployed. 3.   The dent coupling portion is set to a size that allows the ring portion of the steering wheel to be covered by the airbag that has been inflated when viewed from the driver side. Or a steering ring wheel airbag according to 2;   The steering wheel airbag according to any one of claims 1 to 3, wherein the vehicle body side wall portion and the occupant side wall portion are connected to each other only by the peripheral edge coupling portion.

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