Air bag device

Abstract

To provide an air bag device in which an air bag can be rapidly developed in the right side and the left side while delaying development speed of the air bag in the upper side and in the rear side.SOLUTION: An air bag device 30 comprises: an air bag 31; an inflator 32 which supplies the air bag 31 with inflation gas; and a regulation belt 40 which is wound around the air bag 31 in a folded state to continuously cover an upper side of the air bag 31, a rear side thereof, and a lower side thereof. The regulation belt 40 is ruptured by pressure received from the air bag 31 from the time when the air bag 31 starts expanding to completion of the expansion. The regulation belt contacts with the air bag 31 until the rupture to suppress expansion of the air bag 31 in the upper side, in the rear side, and in the lower side. The regulation belt 40 is wound around the air bag 31 so that the right and left sides of the air bag 31 in the folded state are not covered.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to an airbag device mounted in a vehicle. [Background technology]

[0002] Vehicles have conventionally been equipped with airbag devices for protecting occupants. Patent Document 1 describes a configuration in which a cover member covering a folded airbag maintains a state in which the cover member covers the upper and rear parts of the airbag even after the airbag starts to inflate, thereby suppressing the airbag from inflating upwards and backwards. This retards the upward and rearward deployment speed of the airbag when it inflates, thereby suppressing the impact that the airbag receives from the occupant even if the airbag is activated when the occupant is close to the airbag. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7212170 Summary of the Invention [Problem to be solved by the invention]

[0004] When a vehicle collides obliquely rather than head-on, the occupant moves not only forward but also to the left and right. Therefore, in order for the airbag to properly catch the occupant, it is desirable for the airbag to quickly deploy to the left and right. On the other hand, in the configuration described in Patent Document 1, the cover member covers almost the entire area of ​​the airbag in the folded state, so that the deployment of the airbag to the left and right may be inhibited and delayed by the cover member.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an airbag device that can delay the upward and rearward deployment speed of an airbag and can quickly deploy the airbag to the right and left. [Means for solving the problem]

[0006] A representative configuration of an airbag device according to the present invention for solving the above-mentioned problems is an airbag device mounted on a vehicle, comprising: an airbag that is folded and stored, and that inflates when inflation gas is supplied thereto; an inflator that supplies the inflation gas to the airbag; and a wrapping member that is wrapped around the airbag so as to continuously cover the upper, rear, and lower sides of the airbag in a folded state, the wrapping member being ruptured by the pressure received from the airbag between the start of inflation and the completion of inflation, and being in contact with the airbag to suppress the expansion of the airbag upward, rear, and downward from the start of inflation until it is ruptured, and the wrapping member is wrapped around the airbag so as not to cover the right and left sides of the airbag in a folded state.

[0007] According to the airbag device of the present invention, the speed at which the airbag deploys upward and rearward can be delayed, and the airbag can be deployed quickly to the right and left. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a front view of a steering wheel on which the airbag device is mounted. [Diagram 2] FIG. [Diagram 3] 2 is a cross-sectional view of the steering wheel taken along the line AA shown in FIG. 1. [Figure 4] FIG. 4 is a plan view of the regulation belt before being wrapped around the airbag. [Diagram 5] FIG. 4 is a side view of the airbag and the regulation belt. [Figure 6] 11A and 11B are diagrams illustrating the operation of the restriction belt when the airbag is inflated. [Figure 7] 11A and 11B are diagrams illustrating the operation of the restriction belt when the airbag is inflated. [Figure 8]FIG. 13 is a top view of the airbag and the restraint belt during inflation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An airbag device 30 according to one embodiment of the present invention will be described below with reference to the drawings. In the following description, the left-right direction means the left and right directions when a vehicle 50 equipped with the airbag device 30 is traveling straight ahead. The front-rear direction means the front and rear directions when the vehicle 50 is traveling straight ahead. The up-down direction means the upper and lower directions in the vertical direction. Note that the dimensions, materials, shapes, relative positions, etc. of the components described below are not intended to limit the scope of the present invention to only those unless otherwise specified.

[0010] The airbag device 30 according to this embodiment is mounted on a steering wheel 10 and protects a driver M (FIG. 6) as an occupant. FIG. 1 is a front view of the steering wheel 10 on which the airbag device 30 is mounted. FIG. 2 is a left side view of the steering wheel 10. FIG. 3 is a cross-sectional view of the steering wheel 10 taken along the line AA shown in FIG. 1. In FIGS. 1 to 3, the airbag 31 at the time of complete inflation is indicated by a two-dot chain line.

[0011] 1 to 3, the steering wheel 10 includes a steering section 1 that is gripped and rotated by a driver M, and a boss section 2 that is connected to a steering shaft 55 (steering axis) of a vehicle 50. The steering wheel 10 also includes an airbag device 30 and a pad 37 that covers the airbag device 30, a horn switch (not shown), and the like from the rear.

[0012] The steering unit 1 is a substantially rectangular member with long sides in the left-right direction and short sides in the up-down direction in a free state in which the steering unit 1 is not rotated. In other words, in the free state, the width L1 in the up-down direction of the outer hull of the steering unit 1 is narrower than the width L2 in the left-right direction. The steering unit 1 is formed of a metal core 1x, a cover layer 1y made of synthetic resin and having cushioning properties that covers the core 1x, and a surface layer 1z made of synthetic resin or leather that covers the cover layer 1y, except for a portion covered by a pad 37 described later.

[0013] The steering unit 1 has a right grip part 1a disposed on the right side of the boss part 2 and held by the driver M with his right hand during normal driving, and a left grip part 1b disposed on the left side of the boss part 2 and held by the driver M with his left hand during normal driving. The right grip part 1a and the left grip part 1b are connected by an upper connecting part 1c extending in the left-right direction at the upper part of the steering unit 1, and are connected by a lower connecting part 1d extending in the left-right direction at the lower part of the steering unit 1. The parts of the upper connecting part 1c and the lower connecting part 1d of the steering unit 1 that are covered with the pad 37 are formed only of the core metal 1x without the coating layer 1y or the surface layer 1z.

[0014] The boss portion 2 is a metal member disposed substantially at the center of the steering wheel 10, and is connected to the steering shaft 55. Specifically, the boss portion 2 and the steering shaft 55 are connected to each other by fastening the tip of the steering shaft 55 with a nut 56 while the tip of the steering shaft 55 is inserted and fitted into the shaft hole 2a of the boss portion 2. The boss portion 2 is held by a metal core 2x, which is a plate-shaped metal plate connected to the metal core 1x of the steering portion 1, thereby connecting the boss portion 2 and the steering portion 1. Note that, although the boss portion 2, the metal core 2x, and the metal core 1x of the steering portion 1 are integrally formed by die-casting in this embodiment, these members may be formed separately and connected by welding or screws.

[0015] The driver M grips the right grip portion 1a and the left grip portion 1b, respectively, and changes the traveling direction of the vehicle 50 by rotating and steering the steering unit 1 around the steering shaft 55 connected to the boss portion 2. In this embodiment, the vehicle 50 is equipped with a steer-by-wire system, and a sensor (not shown) detects the rotation angle of the steering shaft 55, which rotates in response to the rotational steering of the steering unit 1, and the vehicle 50 steers the tires to change the traveling direction in response to this detection result. Note that the vehicle 50 may be configured to mechanically steer the tires via the steering shaft 55 when the steering wheel 10 is rotated.

[0016] The airbag device 30 includes an airbag 31, an inflator 32 that supplies inflation gas to the airbag 31, a case 33 that holds the airbag 31 and the inflator 32, and a retainer 34 housed inside the airbag 31. The airbag device 30 also includes a regulation belt 40 (wrapping member) that is wrapped around the airbag 31 in a folded state, and a pad 37 that holds the case 33.

[0017] The pad 37 is a member made of synthetic resin, and serves both as an exterior of the steering wheel 10 and as a component of the airbag device 30. The pad 37 breaks when the airbag 31 inflates to form an opening 5, and allows the airbag 31 to be deployed from the opening 5. The pad 37 has a top surface portion 37a that covers the rear of the airbag 31 in a folded state, and a side wall portion 37b that extends forward from the top surface portion 37a and covers a side wall portion 33b of the case 33, which will be described later, from the outside.

[0018] The top surface 37a has a thin-walled portion 37a1 formed to be thin so as to break under the pressure of the inflating airbag 31, and door portions 37a2, 37a3 which are upper and lower portions of the thin-walled portion 37a1. When the thin-walled portion 37a1 breaks with the inflation of the airbag 31, the upper door portion 37a2 rotates upward and the lower door portion 37a3 rotates downward to open, thereby forming an opening 5. In addition, the side wall portion 37b has an engagement hole 37b1 with which a hook portion 33b1 formed on the side wall portion 33b of the case 33 engages.

[0019] The inflator 32 is a generally cylindrical member that generates inflation gas and has a discharge port 32a for discharging the generated inflation gas. The inflator 32 has a flange portion 32b that extends in the radial direction of the cylindrical shape from the surface where the discharge port 32a is formed, as a portion that is connected to the case 33. The inflator 32 is electrically connected to a control device (not shown) by a lead wire (not shown), and is activated by an activation signal input from the control device via the lead wire to generate inflation gas.

[0020] The airbag 31 is a bag-shaped member made of a base fabric made of synthetic fibers such as nylon, and is accommodated in the steering wheel 10 in a folded state. A circular opening (not shown) is formed in the front of the airbag 31, and a portion of the inflator 32 where a discharge port 32a is formed is inserted into the airbag 31 through this opening. The airbag 31 is folded so that it does not spread out significantly in the folded state and maintains its shape.

[0021] The airbag 31 at the time of completion of inflation includes a rear wall portion 31a1 at the rear side thereof, which is a portion that receives the driver M, a front wall portion 31a2 at the front side thereof, which is a portion that is supported by the steering portion 1 of the steering wheel 10, a left wall portion 30a3 at the left side thereof, and a right wall portion 30a4 at the right side thereof. The airbag 31 at the time of completion of inflation covers the entire area of ​​the steering portion 1 of the steering wheel 10 from the rear. In order to make the rear wall portion 31a1 a surface that is as vertical as possible, the width L3 in the front-rear direction of the upper portion of the airbag 31 at the time of completion of inflation is configured to be wider than the width L4 in the front-rear direction of the lower portion. A tether 66 is provided inside the airbag 31 to define the width in the front-rear direction of the airbag 31 at the time of completion of inflation.

[0022] The case 33 includes a bottom wall 33a having a substantially rectangular plate shape and a side wall 33b extending rearward from the outer edge of the bottom wall 33a. The inflator 32 is inserted through an insertion hole (not shown) into the bottom wall 33a. The side wall 33b is connected to the core metal 2x of the boss 2 of the steering wheel 10 through a horn switch (not shown). The left and right side wall 33b have rear ends formed with hook-shaped hooks 33b1 that engage with engagement holes 37b1 in the side wall 37b of the pad 37. The hooks 33b1 engage with the engagement holes 37b1 to position the pad 37 relative to the case 33, and a rivet 61 is inserted through the side wall 33b of the case 33 and the side wall 37b of the pad 37 to connect the pad 37 to the case 33.

[0023] The restriction belt 40 is a belt-shaped member made of synthetic fiber such as nylon, and is wrapped around the airbag 31 so as to continuously cover the upper, rear, and lower parts of the airbag 31 in the folded state. The restriction belt 40 contacts the airbag 31 and suppresses the upward, rear, and downward inflation of the airbag 31 from when the airbag 31 starts to inflate until the restriction belt 40 breaks. The detailed configuration and function of the restriction belt 40 will be described later.

[0024] The airbag 31, the inflator 32, and the regulation belt 40 are fixed to the bottom wall 33a of the case 33 via a retainer 34, which is a substantially rectangular annular metal plate housed inside the airbag 31. Specifically, the periphery of the opening (not shown) of the airbag 31 and the regulation belt 40 are sandwiched between the front surface of the retainer 34 and the rear surface of the bottom wall 33a of the case 33. The upper surface of the flange 32b of the inflator 32 is pressed against the lower surface of the bottom wall 33a of the case 33. In this state, a bolt 62 (screw member) is inserted through through holes formed in the periphery of the opening of the airbag 31, the regulation belt 40, the bottom wall 33a of the case 33, and the flange 32b of the inflator 32, respectively, and a nut 63 is fastened. As a result, the airbag 31, the inflator 32, and the regulation belt 40 are fixed to the bottom wall 33a of the case 33.

[0025] Next, the operation of the airbag device 30 will be described. First, when a collision or the like of the vehicle 50 is detected by a sensor (not shown), an activation signal is input from a control device (not shown) to the inflator 32, which activates the inflator 32 to generate inflation gas. This causes the inflation gas to be supplied to the inside of the airbag 31, and the airbag 31 begins to inflate.

[0026] The airbag 31 that has started to inflate first comes into contact with the top surface portion 37a of the pad 37. Next, as the airbag 31 further inflates, the thin-walled portion 37a1 of the top surface portion 37a is broken by the pressure from the airbag 31, and the door portions 37a2 and 37a3 are pressed by the airbag 31 and rotate to form the opening 5. As will be described later, the restriction belt 40 restricts the upward, backward, and downward inflation of the airbag 31 while wrapped around the airbag 31, but this restriction is not strong enough to prevent the pad 37 from breaking.

[0027] After that, when the airbag 31 further inflates, the airbag 31 is deployed to the outside of the steering wheel 10 through the opening 5, and completes the inflation while breaking the wrapped regulation belt 40. Also, the driver M who moves with the collision of the vehicle 50 is received and protected by the airbag 31.

[0028] Next, a detailed configuration of the regulation belt 40 will be described. Fig. 4 is a plan view of the regulation belt 40 before being wrapped around the airbag 31. Fig. 5 is a side view of the airbag 31 and the regulation belt 40 in a folded state. For ease of explanation, only the outline of the airbag 31 is shown in Fig. 5.

[0029] As shown in FIG. 4 and FIG. 5, the regulation belt 40 is an elongated member, and is wound around the airbag 31 in the folded state so that the longitudinal direction of the regulation belt 40 is the winding direction. The regulation belt 40 is wound around the airbag 31 so as to continuously cover the upper, rear, and lower sides of the airbag 31 in the folded state. That is, the regulation belt 40 includes an upper cover portion 40a that covers the upper side of the airbag 31 in the folded state, a rear cover portion 40b that covers the rear, and a lower cover portion 40c that covers the lower side. Note that the upper cover portion 40a covering the upper side of the airbag 31 does not necessarily have to cover the entire upper part of the airbag 31, but only needs to be wound around the upper part of the airbag 31. The same applies to the rear cover portion 40b and the lower cover portion 40c. The regulation belt 40 does not cover the right and left sides of the airbag 31 in the folded state, leaving them open. In other words, the regulation belt 40 is not looped around the right and left sides of the airbag 31 in the folded state.

[0030] Moreover, one end 40x and the other end 40y in the longitudinal direction of the regulation belt 40 partially cover the front of the airbag 31 in the folded state. Two through holes 41 penetrating the regulation belt 40 in the thickness direction are formed on the one end 40x side relative to the longitudinal center of the regulation belt 40. Moreover, the one end 40x of the regulation belt 40 is folded back so as to shorten the longitudinal dimension and sewn at a seam 40x1 around the through hole 41. Similarly, two through holes 42 penetrating the regulation belt 40 in the thickness direction are formed on the other end 40y side relative to the longitudinal center of the regulation belt 40. Moreover, the other end 40y of the regulation belt 40 is folded back so as to shorten the longitudinal dimension and sewn at a seam 40y1 around the through hole 42. In this way, the regulation belt 40 is formed double in the portion where the through holes 41 and 42 of the regulation belt 40 are arranged, and strength is ensured.

[0031] Further, the lower cover portion 40c of the regulation belt 40 is provided with a slit 43 that is cut so as to reduce the thickness. The width of the regulation belt 40 in the short side direction perpendicular to the longitudinal direction and thickness direction is narrow from one end portion 40x in the longitudinal direction to the slit 43. In this manner, the portion of the regulation belt 40 where the slit 43 is formed is thin in thickness and narrow in the short side direction, and therefore is weaker in strength than other portions and more likely to break.

[0032] The regulation belt 40 is fixed to the airbag 31 at one end 40x and the other end 40y via a bolt 62 inserted through the retainer 34. That is, when the bolt 62 is inserted through through holes (not shown) of the retainer 34, the airbag 31, and the case 33 to fix them, the regulation belt 40 is wrapped around the airbag 31, and the bolt 62 is also inserted through the through holes 41 and 42, so that the regulation belt 40 is fixed to the airbag 31 via the bolt 62. That is, the through hole 41 of the regulation belt 40 is a fixing portion (first fixing portion) fixed to the airbag 31 on the one end 40x side in the winding direction of the regulation belt 40 around the airbag 31, and the through hole 42 is a fixing portion (second fixing portion) fixed to the airbag 31 on the other end 40y side in the winding direction.

[0033] The method of fixing the regulation belt 40 to the airbag 31 is not limited to the above method, and the regulation belt 40 may be fixed to the airbag 31 by sewing it, for example. However, fixing via the bolt 62 as in the present embodiment is preferable because the regulation belt 40 can be easily fixed to the airbag 31 by simply inserting the bolt 62 through the through holes 41, 42 of the regulation belt 40 when fixing the airbag 31.

[0034] In addition, with respect to the winding direction of the regulation belt 40 around the airbag 31, the length L5 between the through hole 41 and the through hole 42 in the regulation belt 40 is set to be longer than the circumferential length L6 between the position corresponding to the through hole 41 and the position corresponding to the through hole 42 in the regulation belt 40 in the airbag 31. By providing a difference in length between the fixed portions of the airbag 31 and the regulation belt 40 in this manner, an excess portion is formed in the regulation belt 40, and this excess portion is a folded-over portion 40v in which the regulation belt 40 is folded over. A tip portion 40v1 of the folded-over portion 40v is attached and fixed to the rear cover portion 40b by an adhesive tape 40w. The adhesive strength of the tape 40w is set to an adhesive strength such that the fixation is released by the pressure received from the airbag 31 before the slit 43 described later breaks. In this embodiment, the folded-over portion 40v is disposed in the rear cover portion 40b of the regulation belt 40, but may be disposed in the upper cover portion 40a or the lower cover portion 40c. Furthermore, the tip 40v1 of the folded over portion 40v may be fixed to the regulation belt 40 by other methods such as sewing, or may not be fixed to the regulation belt 40.

[0035] Next, the operation of the restriction belt 40 when the airbag 31 is inflated will be described. Figures 6 and 7 are schematic diagrams sequentially showing the operation of the restriction belt 40 when the airbag 31 is inflated, with the airbag 31 and the restriction belt 40 viewed from the left side. Figure 8 is a diagram of the airbag 31 and the restriction belt 40 viewed from above during inflation.

[0036] 6A, when inflation gas is first supplied to the airbag 31 and the airbag 31 starts to inflate, the regulation belt 40 starts to spread rearward together with the airbag 31 due to the pressure the regulation belt 40 receives from the airbag 31. At this stage, since the amount of inflation of the airbag 31 is small, the folded-over portion 40v of the regulation belt 40 is not unfolded, so the airbag 31 receives almost no reaction force from the regulation belt 40, and the inflation of the airbag 31 is hardly suppressed.

[0037] Next, as shown in FIG. 6B, when the airbag 31 further inflates, the regulation belt 40 further spreads rearward, whereby the folded-over portion 40v of the regulation belt 40 is stretched and unfolded. At this time, the tape 40w that has been fixing the tip 40v1 of the folded-over portion 40v comes off. When the folded-over portion 40v is unfolded, the regulation belt 40 does not spread any further, and the reaction force that the airbag 31 receives from the regulation belt 40 increases. This suppresses the expansion of the upper, rear, and lower portions of the airbag 31 around which the regulation belt 40 is looped, and suppresses the upward, rearward, and downward expansion of the airbag 31.

[0038] Here, the regulation belt 40 is wound around the airbag 31 so as to open the left and right sides of the airbag 31 in the folded state without covering them. Therefore, even when the folded-over portion 40v of the regulation belt 40 is unfolded, the reaction force of the regulation belt 40 hardly acts on the left and right parts of the airbag 31. Therefore, as shown in FIG. 8, the airbag 31 is not restricted from expanding to the left and right, and is rapidly deployed and inflated so as to protrude and spread out to the left and right from the regulation belt 40. By rapidly deploying the airbag 31 to the left and right in this manner, even if the vehicle 50 collides obliquely and the driver M moves to the left front or right front due to the impact, the driver M is received by the airbag 31 that protrudes to the left and right from the regulation belt 40 and spreads out. In addition, the left and right positions of the driver M with respect to the airbag 31 are determined by the parts of the airbag 31 that protrude to the left and right from the regulation belt 40 and spread out, so that the driver M is received near the center of the airbag 31 when the airbag 31 completes its inflation and is appropriately protected.

[0039] 7A, when inflation gas is further supplied to the airbag 31, the pressure that the regulation belt 40 receives from the airbag 31 becomes even greater, and the stress of the regulation belt 40 becomes greater, causing the weakly formed slit 43 of the regulation belt 40 to break. As a result, the regulation belt 40 is released from wrapping around the airbag 31, the airbag 31 no longer receives a reaction force from the regulation belt 40, and the restriction of the upward, backward, and downward inflation of the airbag 31 by the regulation belt 40 is released.

[0040] 7B, when inflation gas is further supplied to the airbag 31, the airbag 31 inflates in all directions except the forward direction, completing the inflation. Note that the inflation of the airbag 31 in the forward direction is restricted by a reaction force received from the steering section 1 of the steering wheel 10 as the airbag 31 comes into contact with the steering section 1.

[0041] In this manner, the restriction belt 40 contacts the airbag 31 and suppresses rearward, upward, and downward expansion of the airbag 31 from when the airbag 31 starts to expand until the restriction belt 40 breaks. This makes it possible to slow down the upward, rearward, and downward deployment speed of the airbag 31 when it expands, i.e., the deployment speed in the direction toward the driver M, and makes it possible to suppress the impact that the driver M receives from the airbag 31 even if the airbag 31 is activated when the distance between the driver M and the airbag 31 is short.

[0042] Here, the following effect is achieved by the restriction belt 40 delaying the downward deployment speed of the airbag 31. That is, when the airbag 31 is activated in a state where the distance between the driver M and the airbag 31 is short and the downward deployment speed of the airbag 31 is fast, the vicinity of the chest of the driver M is strongly pressed downward by the airbag 31, and a large pulling load may be applied to the neck of the driver M. In contrast, by the restriction belt 40 delaying the downward deployment speed of the airbag 31 as in this embodiment, the vicinity of the chest of the driver M is prevented from being strongly pressed downward by the airbag 31, so that it is possible to prevent a large pulling load from being applied to the neck of the driver M. This configuration is particularly effective in a configuration in which the steering part 1 of the steering wheel 10 is not circular and the width L1 in the vertical direction of the outer periphery of the steering part 1 is narrower than the width L2 in the horizontal direction as in this embodiment. That is, when the steering unit 1 has a circular configuration, even if the driver M leans forward when the airbag device 30 is activated, the head of the driver M interferes with the upper part of the steering unit 1, making it difficult for the driver M's head to be positioned above the steering unit 1. On the other hand, when the vertical width L1 of the steering unit 1 is narrow as in this embodiment, the head of the driver M is unlikely to interfere with the steering unit 1, making it easy for the head to be positioned above the steering unit 1. Therefore, when the airbag 31 strongly presses the area around the driver M's chest downward, a large pulling load is likely to be applied to the driver M's neck, and there is an increased need to suppress this.

[0043] As described above, since the regulation belt 40 is wrapped around the airbag 31 so as not to cover the left and right sides of the airbag 31 in the folded state, the airbag 31 is deployed quickly without being restricted from expanding to the left and right. Therefore, according to the airbag device 30 of this embodiment, the regulation belt 40 can slow down the upward and rearward deployment speed of the airbag 31 and can deploy the airbag 31 quickly to the right and left.

[0044] Also, the slit 43 of the regulation belt 40 is arranged in the lower cover part 40c which covers the lower part of the airbag 31 in the folded state. Therefore, when the slit 43 breaks, the airbag 31 first expands so as to spread downward where the winding of the regulation belt 40 is first released (see FIG. 7A). As a result, even if the driver M is a woman and the distance between the driver M's chest and the steering wheel 10 is likely to be narrow, the airbag 31 is easily inserted between the driver M's chest and the steering wheel 10, and the driver M's chest is easily protected. That is, the regulation belt 40 retards the downward deployment speed of the airbag 31 before it breaks, suppressing a large pulling load on the driver M's neck, and after it breaks, it protects the driver M's chest without hindering the downward deployment of the airbag 31 as much as possible. If the above point is not taken into consideration, the slit 43 may be arranged in a position other than the lower cover part 40c.

[0045] In addition, the formation of the folded-over portion 40v in the regulation belt 40 provides the following effects. That is, it is preferable from an economical point of view that the airbag device 30 and its components are generally usable for various vehicle models and locations. On the other hand, the suitable time from when the airbag 31 starts to inflate until the restriction of the inflation of the airbag 31 by the regulation belt 40 is released varies depending on the vehicle model and location in which the airbag device 30 is installed. Here, it is after the folded-over portion 40v is stretched and the folding is released that a large stress occurs inside the regulation belt 40 due to the pressure from the inflating airbag 31. Therefore, by adjusting the length L5 between the fixed portions of the regulation belt 40 to the airbag 31 and adjusting the folding amount of the folded-over portion 40v, the timing at which a large stress occurs inside the regulation belt 40 can be easily adjusted, and the timing at which the regulation belt 40 breaks can be easily adjusted.

[0046] In this embodiment, the airbag device 30 is mounted on the steering wheel 10, but the present invention is not limited to this, and the airbag device 30 may be mounted on other parts. For example, the same effect as above can be obtained by mounting the airbag device 30 on the instrument panel in front of the passenger seat of the vehicle 50 to protect the passenger sitting in the passenger seat. [Explanation of symbols]

[0047] 1...Steering portion, 2...Boss portion, 10...Steering wheel, 30...Airbag device, 31...Airbag, 32...Inflator, 34...Retainer, 40...Restriction belt (wrapping member), 40v...Folded portion, 41...Through hole (first fixing portion), 42...Through hole (second fixing portion), 43...Slit, 50...Vehicle, 55...Steering shaft, 62...Bolt (screw member)

Claims

1. In an airbag device mounted in a vehicle, an airbag that is folded and stored and inflated by supplying inflation gas; an inflator for supplying the inflation gas to the airbag; a wrapping member that is wrapped around the airbag so as to continuously cover the upper, rear, and lower sides of the airbag in a folded state, the wrapping member being broken by pressure received from the airbag during the period from when the airbag starts to inflate until when the airbag completes its inflation, and being in contact with the airbag during the period from when the airbag starts to inflate until when the wrapping member is broken, the wrapping member suppressing the inflation of the airbag in the upper, rear, and downward directions; Equipped with The airbag device according to claim 1, wherein the wrapping member is wrapped around the airbag so as not to cover the right and left sides of the airbag in a folded state.

2. The winding member is a first fixing portion fixed to the airbag at one end side in a wrapping direction of the airbag; a second fixing portion fixed to the airbag at the other end side in the wrapping direction; a folded portion formed by folding the wrapping member such that a length in the wrapping direction between the first fixing portion and the second fixing portion is set to be longer than a circumferential length in the wrapping direction between a position of the airbag corresponding to the first fixing portion and a position of the airbag corresponding to the second fixing portion; 2. The airbag device according to claim 1, further comprising:

3. 3. The airbag device according to claim 2, wherein the first fixing portion and the second fixing portion are each fixed to the airbag via a screw member that is inserted into a retainer provided inside the airbag.

4. 2. The airbag device according to claim 1, wherein the wrapping member has a slit that breaks when subjected to pressure from the inflating airbag.

5. 5. The airbag device according to claim 4, wherein the slit is provided in a portion of the wrapping member that covers a lower portion of the airbag in a folded state.

6. 6. The airbag device according to claim 1, wherein the airbag is mounted on a steering wheel.

7. The steering wheel includes a boss portion connected to a steering shaft of the vehicle, and a steering portion that is gripped by a driver and rotated around the steering shaft, 7. The airbag device according to claim 6, wherein, when the steering portion is not rotated, the width of the outer casing of the steering portion in the up-down direction is narrower than the width of the outer casing in the left-right direction.

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