Lower limb protecting air bag

A lower limb protecting air bag, folded stored in front of an occupant seated in a seat and inflatable to cover the front of the lower limbs of the occupant by inflation gas supplied therein, includes: a main body inflation part configured to cover the front of the lower limbs of the occupant when inflation is completed; and a shin protection part arranged at least on one end side of the main body inflation part in the horizontal direction and projectable backward from the main body inflation part for covering the lateral side of the shins of the occupant in the inflation completed time, wherein the shin protection part completes inflation with an internal pressure higher than that of the main body inflation part.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2014-171015, filed on Aug. 25, 2014, the entire contents of which are incorporated herein by reference.

BACKGROUND

1. Field of the Invention The invention relates to a lower limb protecting air bag which is folded and stored in front of an occupant seated in a seat and, when inflation gas is supplied therein, is inflated to cover the front side of the lower limbs of the occupant.

2. Description of the Related Art

Conventionally, there is known a lower limb protecting air bag which includes a main body inflation part, when the inflation of the air bag is completed, for covering the front side of the lower limbs of an occupant, and a shin protection part, in the inflation completed time, projected from the main body inflation part backwardly downward for covering the lateral sides of the lower areas of the shins of the occupant. In this conventional lower limb protecting air bag, the shin protection part is formed continuously and integrally with the main body inflation part (see, for example, JP-A-2004-168280).

However, in the conventional lower limb protecting air bag, since the shin protection part is disposed such that it projects partially from the lower end side of the main body inflation part to cover the right and left sides of the lower area of the shins of the occupant, it is hard to inflate with large thickness by increasing its volume. Therefore, in a vehicle collision such as oblique collision and off-set collision, when an occupant seated in a seat moves obliquely forward, there is room for improvement in exactly receiving the shins of the obliquely forward moving occupant by the shin protection part.

SUMMARY

The invention aims at solving the above problem and thus it is an object of the invention to provide a lower limb protecting air bag capable of exactly protecting the shins of an occupant moving obliquely forward.

According to an aspect of the invention, there is provided a lower limb protecting air bag, folded stored in front of an occupant seated in a seat and inflatable to cover the front of the lower limbs of the occupant by inflation gas supplied therein, including: a main body inflation part configured to cover the front of the lower limbs of the occupant when inflation is completed; and a shin protection part arranged at least on one end side of the main body inflation part in the horizontal direction and projectable backward from the main body inflation part for covering the lateral side of the shins of the occupant in the inflation completed time, wherein the shin protection part completes inflation with an internal pressure higher than that of the main body inflation part.

In the lower limb protecting air bag of the invention, in the inflation completed time, the shin protection part projectable backward from the main body inflation part for covering the lateral sides of the shins of the occupant is structured to complete its inflation with an internal pressure higher than that of the main body inflation part, whereby, when it receives the shins of an obliquely forward moving occupant, it can receive the shins with a proper stiffness. Therefore, when it receives the shins of the occupant, it can receive the shins in such a manner that the projecting tip end side of the main body inflation part is prevented from bending outward in the horizontal direction, thereby preventing the obliquely forward moving shins from slipping through it. Thus, the shins can be exactly received by the shin protection part.

Thus, in the lower limb protecting air bag of the invention, the shins of the obliquely forward moving occupant can be protected exactly.

Specifically, in the lower limb protecting air bag of the invention, preferably, the shin protection part may be structured to communicate with the main body inflation part and let the inflation gas flow therein through the main body inflation part and, in a communication part enabling communication between the shin protection part and main body inflation part, there may be provided a check valve to prevent the inflation gas supplied into the shin protection part from flowing out toward the main body inflation part.

When the lower limb protecting air bag is structured in this manner, even when the inflation gas is supplied into the shin protection part through the main body inflation part, the inflation gas once supplied into the shin protection part can be prevented from returning into the main body inflation part, whereby the high internal pressure state of the shin protection part in the inflation completed time can be positively maintained.

DETAILED DESCRIPTION OF THE INVENTION

Description is given below of an embodiment of the invention with reference to the drawings. In this embodiment, as shown inFIGS. 1 and 4, description is given of, as an example, a lower limb protecting air bag (which is hereinafter called an air bag simply)40used in a lower limb protecting air bag apparatus (which is hereinafter called an air bag apparatus simply) disposed below a steering column8constituting the vehicle forward side of a driver D seated in a driver seat. Here, in this specification, vertical, horizontal and longitudinal directions correspond to, unless otherwise mentioned, the vertical, horizontal and longitudinal directions of the air bag apparatus S when mounted on a vehicle.

The steering column8, as shown inFIGS. 1 and 4, includes a column main body9and a column cover12for covering the outer peripheral side of the column main body9. The column main body9, as shown inFIG. 1, is constituted of a main shaft10and a column tube11for covering the periphery of the main shaft10.

The air bag apparatus S, as shown inFIGS. 1 to 4, includes a folded air bag40, an inflator27for supplying expansion gas to the air bag40, a case21capable of storing the folded air bag40and inflator27and having an opened vehicle backward side, and an air bag cover15for covering the vehicle backward side of the opening21aof the case21.

The air bag cover15is made of polyolefin-based thermoplastic elastomer and is capable of covering the opening21aon the vehicle backward side of the case21. This air bag cover15, as shown inFIGS. 1 to 4, is disposed on the lower panel13bside of an instrument panel13including an upper panel13aand a lower panel13b.In this embodiment, it includes a door part16disposed so as to cover the opening21aof the case21and a connecting wall part19extending forward from the periphery of the door part16to be connected to the peripheral wall part23of the case21. The door part16, as shown inFIGS. 2 and 4, includes in its periphery a breakage expected thin portion17having a substantially H-like shape when viewed from the vehicle backward side, and hinge portions18disposed on both upper and lower sides and serving as the opening centers of the door part when it is opened, while the door part16is opened on both upper and lower sides when it is opened.

The case21is made of sheet metal and, as shown inFIGS. 2 and 3, includes a substantially square-shaped bottom wall part22disposed on the vehicle forward side and a substantially square-shaped peripheral wall part23extending backward from the peripheral edge of the bottom wall part22, while the vehicle backward side thereof is opened. The bottom wall part22includes: insertion holes (not shown) through which bolts36to be provided in the retainer34(which are described later) of the inflator27can be projected; and, a projection22aprojected backwardly to be contactable with the outer peripheral surface29aof the main body part29(which is described later) of the inflator27. Also, the peripheral wall part23includes mounting brackets24,25for mounting the case21onto the body1side of the vehicle. The upper mounting bracket24, as shown inFIG. 4, is connected to brackets4,4extending from the body1side instrument panel reinforcement2, whereas the lower mounting bracket25is connected to brackets5,6extending from a center brace and a front body pillar (both of which are not shown) provided on the body1side.

The inflator27, as shown inFIGS. 2 and 3, includes an inflator main body28having a substantially cylindrical outer shape and a retainer34for holding the inflator main body28.

The inflator main body28, as shown inFIG. 3, includes a large-diameter main body part29having a substantially cylindrical shape with its axial direction extending substantially along the horizontal direction, and a small-diameter part30projected from the horizontal- direction one end side (in this embodiment, the left end side) of the main body part29. The small-diameter part30is smaller in diameter than the main body part29and includes a large number of gas discharge ports30acapable of discharging inflation gas G. To the other end side (right end side) of the main body part29, there is connected a connector31with a lead wire32for operation signal input connected thereto. The inflator main body28, in this embodiment, is structured such that it can be operated in the front collision, oblique collision and off-set collision of the vehicle.

The retainer34, as shown inFIGS. 2 and 3, includes a substantially cylindrical hold part35for covering the outer periphery of the inflator main body28and two bolts36,36projected substantially orthogonally to the axial direction of the hold part35.

The hold part35is made of sheet metal and has a substantially cylindrical shape with its axial direction extending substantially along the horizontal direction. It includes, in the portion disposed on the backward side of the inflator main body28, as shown inFIG. 2, a contact portion35acontactable with the outer peripheral surface29aof the main body part29of the inflator main body28when mounted on the vehicle. The contact portion35a,as shown inFIG. 3, is formed in two positions opposed to the bolts36on the longitudinal direction side. In the position of the hold part35existing forward of the inflator main body28when mounted on the vehicle and intervening between the bolts36, there is formed a penetration hole35bfor insertion of a projection22aof the bottom wall part22of the case21(seeFIG. 3).

In the air bag apparatus S of the embodiment, when the inflator main body28is stored into the hold part35of the retainer34disposed within the folded air bag40and the folded air bag40is stored into the case21, the bolts36of the retainer34are projected from the bottom wall part22of the case21and the nuts37are fastened to the bolts36, thereby mounting the inflator27and air bag40onto the case21. Specifically, the inflator main body28, in the nut37fastening time, is held between the projection22aof the bottom wall part22of the case21and the contact portions35aof the hold part35of the retainer34, whereby it is retained by the retainer34.

The air bag40, as shown inFIG. 5, in this embodiment, includes a bag main body41inflatable by inflation gas supplied therein, and an internal tether65disposed within the bag main body41.

The bag main body41, as shown by two-dot lines inFIGS. 1 and 4and as shown inFIGS. 14 and 15, when its inflation is completed, is disposed to cover the front of the lower limbs of the driver D seated in the driver seat, has a substantially rectangular shape in the inflation completed time, and is capable of protecting the driver D from the right and left shins L to the knees K (KL, KR). In the bag main body41, as shown inFIGS. 6 and 9, the peripheral edges of a back wall portion41bdisposed on the steering column8side in the inflation completed time and a front wall portion41adisposed on the driver D side the in inflation completed time respectively having substantially the same outer shape are connected to each other, thereby forming a bag-like shape. The bag main body41, in this embodiment, includes a main body inflation part42for covering the front of the lower limbs LB of the driver D in the inflation completed time, and a shin protection part49disposed on the outer end side (in this embodiment, on the right side) of the main body inflation part42in the horizontal direction for covering the lateral side (right side) of the shins L (right shin Lr) in the inflation completed time.

The lower end42bside of the main body inflation part42in the inflation completed time constitutes a mounting part43to be mounted on the case21so as to narrow the width of the mounting part43portion, while the upper end42aside portion thereof to be disposed upwardly of the mounting part43in the inflation completed time constitutes a lower limb protection part47capable of protecting the driver D from the shins L to knees K. The lower limb protection part47, in order to cover the front of the driver D from the knees K to shins L in the bag main body41inflation completed time, is interposed between the lower panel13bor steering column8and the knees K or shins L. The horizontal-direction width dimension of the lower limb protection part47increases toward the upper end47a,while the horizontal-direction width dimension of the upper end47aside portion for protecting the knees K is set for a width dimension capable of covering the front of the left and right knees K (KL, KR) of the driver D (see two-dot chain lines shown inFIG. 4). In the upper surface side portion (the portion of the back wall portion41b) of the mounting part43, as shown inFIG. 6, there are formed two insertion holes44,44enabling projection of the bolts36of the retainer34, an open slit45enabling internal insertion of the inflator27(inflator main body28and retainer34), and an insertion hole46capable of insertion of the projection22aof the bottom wall22of the case21. The open slit45is formed such that, with the bag main body41developed flat, it provides a straight shape extending substantially along the horizontal direction. The insertion hole46is formed between the insertion holes44.

The shin protection part49, in this embodiment, is formed to project backward on the right end side of the main body inflation part42in the inflation completed time, thereby covering the horizontally outside (the vehicle outside on the horizontal direction side) of the shins L of the driver D. In this embodiment, the shin protection part49is allowed by a communicating part55(to be discussed later) to communicate with the main body inflation part42, whereby it can receive inflation gas G through the main body inflation part42. Also, the shin protection part49, in the flat developed state of the bag main body41, as shown inFIG. 6, projects rightward from the right edge of the lower end side portion (the portion constituted of the mounting part43and the lower end47bof the lower limb protection part47) of the bag main body41. That is, in the air bag40of this embodiment, the shin protection part49is connected rightward from the lower end47bof the lower limb protection part47for protecting the shins L. Specifically, in this embodiment, it is formed such that its lower end is connected to the lower end42b(the lower end of the mounting part43) of the main body inflation part42. Also, in the inflation completed time of the bag main body41, it is bent relative to the main inflation part42and, with its tip end49a(right end in the flat developed state) facing backward, it projects backward from the main body inflation part42to cover the outside (right side) of the right shin Lr of the driver D seated in the driver seat (seeFIG. 15). The width dimensions of the vertical side and horizontal side (the horizontal side in the flat developed state) thereof in the inflation completed time are set for the dimensions capable of covering the right side of the right shin Lr of the driver D, thereby, in the oblique collision and offset collision of the vehicle, enabling proper protection of the right shin Lr (seeFIGS. 15 and 16) of an occupant seated in the driver seat, that is, the driver D, moving rightward obliquely forward.

The bag main body41of this embodiment also includes a partition wall part54for dividing the shin protection part49and main body inflation part42(seeFIG. 8), while the partition wall part54, as shown inFIGS. 12 and 13, has a communication portion55enabling communication between the shin protection part49and main body inflation part42.

In the bag main body41of this embodiment, in the front wall portion41a,an area ranging from a portion constituting the rear left side of the shin protection part49in the inflation completed time to a portion constituting the main body inflation part42is pinched to project inwardly of the bag main body41while reducing the horizontal side width dimension, thereby forming a tack portion51in the boundary portion between the shin protection part49and main body inflation part42. As shown in Sections A and B ofFIG. 10, the base51bside portion of the tack portion51is sewn (connected) using a sewing thread, whereas the tip end51aside portion thereof is sewn using a sewing thread to the back wall portion41bwith the tip end51afacing outward in the horizontal direction. In the air bag40of this embodiment, the tack portion51constitutes the partition wall part54. That is, the partition part54, with the front wall portion41aformed as a two-superposed portion, includes an outside portion54bto be disposed on the shin protection part49side in the inflation completed time of the bag main body41, and an inside portion54ato be disposed on the main body inflation part42side. A connecting portion53having sewn the base51bside of the tack portion51and a connecting portion52connecting the tip end51aside of the tack portion51to the back wall portion41b,as shown by two-dot chain lines inFIG. 6, are respectively formed to have a linear shape substantially along the longitudinal direction; and, the length dimension thereof is set substantially equal to the longitudinal-direction side width dimension of the shin protection part49in the flat developed state. That is, the tack portion51(partition wall part54) divides the shin protection part49and main body inflation part42, while closing substantially the whole area of the left end side of the shin protection part49.

In the air bag40of this embodiment, the connecting portion52for connecting the tip end51aside (front wall portion41a) of the tack portion51to the back wall portion41bis used as a starting point when, in the inflation completed time, the shin protection part49is bent relative to the main body inflation part42. The front wall portions41aare connected to each other with the connecting portion52between them by the connecting portions53having connected the base51bside of the tack portion51. In the bag main body41of this embodiment, in the front wall portion41awhen it is developed alone prior to formation of the connecting portion53, the distance between connecting portion formation expected portions68,68for forming the connecting portions53(the pinching amount of the front wall portion41aby the tack portion51) L1(see Section B ofFIG. 9) is set for a dimension which, in the inflation completed time of the bag main body41, can project the shin protection part49greatly backward from the main body inflation part42with the connecting portion52as a starting point while maintaining its bent state relative to the main body inflation part42, and also which, when receiving the right shin Lr of the driver D moving rightward obliquely forward, can prevent the shin protection part49from opening greatly relative to the main body inflation part42with the tip end49aside facing horizontally outward (rightward). Also, in the bag main body41of this embodiment, in the back wall portion41bflat developed alone prior to formation of the connecting portion52, a connecting portion formation expected portion69for forming the connecting portion52, as shown in Section A ofFIG. 9, is formed between the connecting portion formation expected portions68,68formed in the front wall portion41a.Here, in Section A ofFIG. 9, for convenience of explanation, the connecting portion formation expected portions68,68are also shown by two-dot chain lines; however, actually, in the back wall portion41b,the connecting portion formation expected portions68,68are not formed.

A communication portion55formed in the partition wall portion54(tack portion51), as shown inFIGS. 11 to 13, includes first and second communication holes56and57respectively formed in the inside and outside portions54aand54b,and a communication passage58constituted of a clearance between the outside and inside portions54band54a.The first and second communication holes56and57are formed apiece in the outside and inside portions54band54awhile they are spaced from each other in the longitudinal direction. Specifically, the first communication hole56to be formed in the inside portion54aserving as the main body inflation part42side (upstream side of the inflation gas G) is situated on the front end side of the inside portion54aserving as the lateral side of the area of the mounting part43, while the second communication hole57to be formed in the outside portion54bserving as the shin protection part49side (downstream side of inflation gas G) is situated on the rear end side of the outside portion54b.The first and second communication holes56and57are formed such that their respective opening areas are not overlapped with each other in the horizontal direction when viewed from right in the inflation completed time of the air bag40(seeFIG. 12and Section A ofFIG. 13). The communication passage58is formed when the inside and outside portions54aand54bare separated from each other by the inflation gas G supplied from the first communication hole56in the inflating time of the main body inflation part42(see Section B ofFIG. 13), while the inflation gas G supplied into the communication passage58from the first communication hole56flows through the second communication hole57into the shin protection part49.

The air bag40of this embodiment, as shown inFIGS. 12 and 13, further includes a flap valve60provided in the peripheral edge57aof the second communication hole57and serving as a check valve for preventing the inflation gas G flown into the shin protection part49from flowing out from the second communication hole57. The flap valve60is formed of a flexible sheet member (in this embodiment, the same base fabric as that of the air bag40), has a substantially rectangular shape capable of closing the second communication hole57(seeFIG. 11) and is disposed to cover the second communication hole57from the shin protection part49side, while its one side is sewn (connected) to the peripheral edge57aof the second communication hole57. When supplying the inflation gas G from the main body inflation part42into the shin protection part49through the first communication hole56and communication passage58, the flap valve60is pressed and opened by the inflation gas G to open the second communication hole57(see two-dot chain lines inFIG. 12, andFIG. 13) and, after the inflation gas G is supplied and the shin protection part49completes inflation, substantially the whole periphery of the outer peripheral edge60aside portion thereof is pressed toward the peripheral edge57aside of the second communication hole57by the internal pressure of the inflation gas G filled in the shin protection part49, thereby maintaining the closed state of the second communication hole57and thus preventing the inflation gas G from flowing out from the second communication hole57(see Section C ofFIG. 13). And, in the bag main body41of this embodiment, since the inflation gas G flown into the shin protection part49is prevented by the flag valve60from flowing out toward the main body inflation part42, the shin protection part49is enabled to complete inflation with a higher internal pressure than the main body inflation part42.

The internal tether65within the bag main body41is used to restrict the thickness in the inflation completed time. The internal tether65is disposed to extend substantially along the horizontal direction in such portion (seeFIG. 14) of the lower limb protection part47of the main body inflation part42of the bag main body41as covers the front of the shins L in the inflation completed time. The internal tether65is formed of a flexible belt-shaped sheet member and, as shown inFIG. 7, connects together the front and back wall portions41aand41band, in the inflation completed state, restricts the distance between them to thereby prevent the shin L protection area from inflating excessively thick.

The front and back wall portions41aand41bof the bag main body41, flap valve60and internal tether65, in this embodiment, are formed of woven fabric constituted of flexible polyester threads, polyamide threads or the like. The front and back wall portions41aand41bare formed of coat cloth coated with silicon-made coating agent for gas leakage prevention.

Next, description is given of a method for mounting the air bag apparatus S of this embodiment onto a vehicle. Firstly, while projecting the bolts36from the insertion holes44, the retainer34is mounted from the open slit45into the air bag40. The air bag40is folded in a state that it can be mounted into the case21and, in order to prevent the folded state from collapsing, the periphery of the folded air bag40is wrapped in a breakable wrapping sheet (not shown). Next, the inflator main body28is inserted through the open slit45into the hold part35of the retainer34within the air bag40. Then, with the bolts36projected from the bottom wall22, the folded air bag40and inflator27are mounted into the case21and the nuts37are fastened to the bolts36projected from the bottom wall22, thereby mounting the air bag40and inflator27onto the case21. After then, the air bag cover15is assembled to the case21, thereby enabling production of an air bag assembly. And, the air bag assembly is mounted and fixed to the body1using the brackets4,5and6, and a connector31with the lead wire32extending from an air bag operation circuit connected thereto is connected to the inflator27. And, the instrument panel13and an undercover (not shown) are mounted, thereby enabling mounting of the air bag apparatus S into the vehicle.

After the air bag apparatus S is mounted into the vehicle, in the front collision, oblique collision or offset collision of the vehicle, when an operation signal is input to the inflator27, the inflation gas G is discharged from the gas discharge ports30aof the inflator27into the air bag40. And, the air bag40, while letting the inflation gas G flow in, inflates to break the wrapping sheet (not shown) and press against the door parts16of the air bag cover15, whereby the door parts16break the breakage expected part17in the periphery and opens vertically with the hinge part18as the center of rotation. And, the air bag40projects from the opening21aof the case21backwardly of the vehicle and completes inflation as shown by two-dot chain lines inFIGS. 1 and 4and inFIGS. 14 and 15.

With the air bag40of the air bag apparatus S of this embodiment, the shin protection part49, in the inflation completed time, projectable backward from the main body inflation part42for covering the lateral side (right side) of the shins L (right shin Lr) of the driver D serving as an occupant is capable of completing its inflation with a higher internal pressure than that of the main body inflation part42. Therefore, in the vehicle oblique collision or offset collision, when the air bag40receives the shins L (right shin Lr) of the driver moving rightward obliquely forward, it can receive the right shin Lr in a properly stiff state. Specifically, the right shin Lr of the driver D can be received by the shin protection part49while the tip end49aprojecting from the main body inflation part42is prevented from bending outward in the horizontal direction, thereby enabling prevention of slip-off of the right shin Lr moving rightward obliquely forward; that is, the shin protection part49can receive the right shin Lr properly. With the air bag40of this embodiment, specifically, in the inflation completed time of the bag main body41, the forwardly situated base49bside portion of the shin protection part49is supported by the lower panel13bof the instrument panel13(seeFIG. 16). Also, in the bag main body41, the main body inflation part42and shin protection part49are separated by the tack portion51formed by pinching the front wall portion41awhile reducing the width dimension on the horizontal side thereof; and, the shin protection part49is connected to the main body inflation part42, while maintaining its bent state relative to the main body inflation part42, by the two portions spaced in the longitudinal direction in the inflation completed time, that is, the connecting portions53connecting the base51bside of the tack portion51and the connecting portion52connecting the tip end51aside of the tack portion51to the back wall portion41b.Therefore, in the air bag40of this embodiment, as shown inFIG. 16, when receiving the right shin Lr of the driver D moving rightward obliquely forward, the shin protection part49receives the right shin Lr of the driver D while, with the49bside thereof supported by the lower panel13b,it is prevented by the two connecting portions52and53spaced in the longitudinal direction against the rotary movement thereof in which the tip end49aside faces outward (rightward) in the horizontal direction and the part49opens relative to the main body inflation part42with the base49bside as a starting point. This can prevent the shin protection part49from moving following the movement of the right shin Lr, thereby enabling the shin protection part49inflated with a high internal pressure to properly restrict the right shin Lr of the driver.

Thus, the air bag40of this embodiment can properly protect the shins L of the driver D moving rightward obliquely forward.

In the air bag40of this embodiment, since the shin protection part49, in the inflation completed time of the air bag main body41, is arranged to cover the horizontal-direction outside, namely, right side of the shins L of the driver D, the shins L of the driver D moving rightward obliquely forward can be prevented from interfering with a door trim.

Specifically, the air bag40of this embodiment supplies the inflation gas G therein through the main body inflation part42and includes, in the communication portion55enabling the shin protection part49and main body inflation part42to communicate with each other, the flap valve60serving as a check valve to prevent the inflation gas G supplied into the shin protection part49from flowing out toward the main body inflation part42. Thus, even in a structure that the inflation gas G is supplied into the shin protection part49through the main body inflation part42, the inflation gas G once supplied into the shin protection part49can be prevented from returning into the main body inflation part42, thereby enabling positive maintaining of the high internal pressure state of the shin protection part49in the inflation completed time. Here, in this embodiment, the shin protection part is structured to supply the inflation gas therein through the main body inflation part. However, so long as inflation can be completed with an internal pressure higher than that of the main body inflation part, it may also be structured such that the inflation gas discharged from the inflator is supplied directly into the shin protection part. Also, in this embodiment, the flap valve60is sewn to the peripheral edge57aof the second communication hole57only by the connecting portion62formed on one side. However, the flap valve60may also be sewn to the peripheral edge of the second communication hole by two connecting portions formed on two opposed sides.

Here, in the air bag40of this embodiment, the shin protection part49is arranged only on the right side (only on the outside in the horizontal direction) of the main body inflation part42. However, this is not limitative but it may also be arranged only on the inside in the horizontal direction of the main body inflation part or may be arranged on both right and left sides of the main body inflation part.

Although this embodiment has been described by way of an air bag used in a lower limb protecting air bag apparatus to be arranged in front of a driver seat, the air bag of the invention, of course, can also apply to a lower limb protecting air bag apparatus to be arranged in front of an assistant driver seat and a lower limb protecting air bag to be arranged in front of a rear seat.