Patent Publication Number: US-7708311-B2

Title: Airbag for front passenger&#39;s seat

Description:
The present application is a continuation of U.S. patent application Ser. No. 11/218,735, filed on Sep. 6, 2005, and claims priority from Japanese Patent Application No. 2004-262788 of Bito, filed on Sep. 9, 2004, Japanese Patent Application No. 2004-262795 of Bito, filed on Sep. 9, 2004, Japanese Patent Application No. 2004-369181 of Bito, filed on Dec. 21, 2004, Japanese Patent Application No. 2004-372072 of Bito, filed on Dec. 22, 2004, Japanese Patent Application No. 2004-372081 of Bito, filed on Dec. 22, 2004, and Japanese Patent Application No. 2004-374237 filed on Dec. 24, 2004, the disclosures of which are hereby incorporated into the present application by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an airbag used for a top-mount type airbag device for front passenger&#39;s seat, which is mountable on top face side of instrument panel (as will be called “dashboard”) in front of front passenger&#39;s seat. 
     2. Description of Related Art 
     In the prior art, Japanese Patent Laid-Open No. 2003-335203, in FIGS. 17 to 28, discloses an airbag for front passenger&#39;s seat. This airbag includes: a gas inlet port for introducing inflation gas in the vicinity of front end thereof as completely inflated; and a protection portion adapted to be thrown against a passenger seated in front passenger&#39;s seat, in a rear side thereof as completely inflated. The protection portion includes two inflatable portions which are disposed side by side in left-right direction, and communicated with each other in the vicinity of the gas inlet port. In this airbag for front passenger&#39;s seat, the two inflatable portions are joined by a joint panel proximate to rear ends thereof. The joint panel is arranged along left-right direction and is adapted to receive and protect the passenger. 
     In the airbag for front passenger&#39;s seat in the prior art, however, since the joint panel for receiving a passenger is formed into a generally planar shape upon airbag deployment, there is a room for improvement in properly protecting the passenger while suppressing a reaction force applied to the passenger, when the joint panel is thrown against the passenger upon airbag inflation. Especially, in order to protect the passenger, there is a challenge in suppressing a reaction force applied to a passenger&#39;s head that is small in mass. 
     In the meantime, in the airbag for front passenger&#39;s seat in the prior art, the two inflatable portions constituting the protection portion are communicated with each other only in a small area in the vicinity of the gas inlet port. With this construction, it is difficult for the two inflatable portions to be inflated uniformly when the protection portion inflates with inflation gas from an inflator, which may slant the joint panel, and may lead to failure in protecting the passenger properly. 
     SUMMARY OF THE INVENTION 
     A first object of the present invention is to provide an airbag for front passenger&#39;s seat which is capable of, when the completely inflated airbag is thrown against a passenger&#39;s head, protecting the head properly by suppressing reaction force. 
     A second object of the present invention is to provide an airbag for front passenger&#39;s seat which is capable of protecting an approaching passenger properly by inflating two projecting parts of a protection portion thereof uniformly. 
     The first object of the present invention is attained by an airbag for front passenger&#39;s seat constructed as follows: 
     The airbag is folded and housed in a top face of instrument panel in front of front passenger&#39;s seat, and upon inflow of inflation gas, the airbag protrudes upward and deploys rearward of vehicle in such a manner as to occupy a space between the top face of the instrument panel and a wind shield located above the instrument panel. The airbag is, when completely inflated, formed into a generally square conical shape whose top is located in a front end. The airbag includes: 
     an inlet port for introducing inflation gas, in the front end vicinity of the airbag as completely inflated; 
     a protection portion contactable with a front seat passenger, in a rear side of the airbag as completely inflated; and 
     a left side wall and a right side wall each arranged generally along front-rear orientation in left and right sides, an upper side wall and a lower side wall each arranged generally along left-right orientation in upper and lower sides, and a rear side wall arranged generally along left-right orientation to confront a passenger, in such a manner as to connect the upper side wall and the lower side wall. The airbag is formed by joining edges of a plurality of base cloths, and includes: 
     an outer panel constituting the left side wall and the right side wall; and 
     an inner panel constituting the upper side wall, the lower side wall and the rear side wall. The inner panel consists of a pair of inner panel base cloths having the same shapes. The inner panel base cloths have such a construction, upon airbag inflation, as to divide an area of the inner panel into two in left-right orientation. Each of the inner panel base cloths has a band shape curved in a generally C-shape, and an outer edge thereof has generally the same shape as an outer edge of a portion of the outer panel constituting the left/right side wall. The inner panel is formed by joining the outer edges of the inner panel base cloths to the outer edges of the portions of the outer panel constituting the left and right side walls, and by joining inner edges of the inner panel base cloths to each other. The protection portion includes shoulder restraining portions disposed generally side by side in left-right orientation in an area from upper part to rear part of the completely inflated airbag, and each of the shoulder restraining portions continuously project from upper part to rear part. 
     With the airbag for front passenger&#39;s seat thus constructed, upon airbag inflation, the protection portion completes in such a shape as is recessed in a transverse center thereof or between the shoulder restraining portions. When the inflated airbag is thrown against a passenger, the left and right shoulder restraining portions projecting rearward firstly bump against the vicinities of left and right shoulders of the passenger, so that forward kinetic energy of the passenger is reduced. Thereafter, ahead of the passenger whose shoulders are restrained by the shoulder restraining portions enters into a recessed area provided between the shoulder restraining portions, and then is restrained and suppressed from moving forward. Accordingly, the airbag is capable of receiving the passenger&#39;s head softly by suppressing reaction force, in a condition that kinetic energy is reduced by the shoulder restraining portions. 
     Therefore, the airbag for front passenger seat thus constructed is capable of, when completely inflated and contacting the passenger&#39;s head, protecting the head properly by suppressing reaction force. 
     In the meantime, in the airbag having above construction, since each of the shoulder restraining portions is arranged from upper side to rear side of the inflated airbag in a continuously protruding manner, thereby providing a continuous recess between the shoulder restraining portions also from upper end of the protection portion generally in vertical orientation. Accordingly, even if a position of the passenger&#39;s head varies in vertical orientation according to a build or sitting posture of the passenger, the airbag receives the head softly while suppressing reaction force. 
     Moreover, a sewn portion which sews up the inner edges of the inner panel base cloths constituting the inner panel is arranged generally all over the front-rear oriented circumference of the airbag, in generally transverse center of the inflated airbag. Since the inner edge of the inner panel base cloth defining the sewn portion has a shorter length than the outer edge of the inner panel base cloth, the sewn portion is positioned inward of an outline of the airbag as completely inflated and viewed from side. Accordingly, the whole base cloths of the airbag is regulated in developing direction by the sewn portion when developed and inflated, so that the rear wall to be deployed toward passenger is prevented from protruding toward passenger upon airbag inflation, and a shape of the completely inflated airbag body is regulated. As a result, the airbag no longer needs a tether or the like which would pull the rear wall forward i.e., in a direction opposite to passenger, and regulate the shape of the airbag body as completely inflated, so that number of parts of the airbag is reduced. 
     Moreover, the above airbag desirably includes, inside thereof, a flow regulating cloth having following constructions: the cloth is arranged to cover the gas inlet port from upper side; 
     the flow regulating cloth is formed into a generally cylindrical shape, and has openings at front and rear ends thereof, so that inflation gas flown in via the inlet port is guided forward and rearward; and 
     upon airbag inflation, at least upper parts of the front and rear openings of the flow regulating cloth are located in higher level than the top face of instrument panel inside the airbag. 
     With this airbag for front passenger&#39;s seat, upon airbag inflation, the inflation gas flown in via the inlet port is supplied into the airbag from the front and rear openings of the flow regulating cloth along front-rear orientation. That is, inflation gas flows into the airbag along front-rear direction, i.e., along the dashboard top face, so that a lower part of the airbag body, especially rear lower part of the airbag is developed along the dashboard. As a result, the airbag is prevented from unnecessarily protruding toward the passenger. 
     In the airbag as constructed above, if the flow regulating cloth is provided, in a laterally symmetric position thereon, with a through hole whose opening area is smaller than an opening area of the front or rear opening, a small amount of inflation gas supplied from the inlet port is released therefrom. The through hole helps stabilize orientation of the front and rear openings, and further stabilize direction of the inflation gas flowing into the airbag, by releasing a small portion of the inflation gas therefrom. As a result, the shoulder restraining portions are supplied with inflation gas properly and generally equally, so that left and right portions of the airbag are developed and inflated evenly in stable manner. 
     In the airbag for front passenger&#39;s seat constructed as above, it is desired that: in each of the shoulder restraining portions, a joint of the outer edge of the portion of the outer panel constituting the left/right side wall and the outer edge of the inner panel base cloth defines a projecting top of the shoulder restraining portion; 
     the airbag is folded firstly through a preparatory folding step, and then through a transverse folding step and a vertical folding step, before being housed; and 
     the preparatory folding is conducted, from a condition that the shoulder restraining portions are lapped with each other in left-right orientation, by holding the projecting tops of the shoulder restraining portions and opening the shoulder restraining portions left and rightwards with respect to an inner joint provided in the inner edges of the left and right inner panel base cloths, while the inner joint is arranged generally along front-rear orientation and is made to confront the gas inlet port, and by folding each of the outer panel portions constituting the left and right side walls on a fold extending along front-rear orientation; and thereby a preparatorily folded airbag has a generally symmetric shape. 
     With this construction, the portion of the outer panel defining the left and right side walls is folded on folds extending along front-rear orientation in a generally laterally symmetric manner, while the inner joint provided in the inner edges of the left and right inner panel base cloths is arranged generally along front-rear orientation and made to confront the gas inlet port. Inner sides of the flattened left and right shoulder restraining portions up to the projecting tops are located in left and right sides of the inner joint. 
     Accordingly, when the airbag unfolds from preparatorily folded state upon deployment, the portion around the inner joint confronting the inlet port swiftly shifts toward a passenger, and then the left and right shoulder restraining portions inflate in a well-balanced manner. That is, since the inner joint vicinity swiftly shifts toward a passenger, even if the shoulder restraining portions are still not inflated enough, the inner sides of the left and right shoulder restraining portions up to the projecting tops, including the inner joint, moves toward the passenger, while securing a generally vertical, wide and flat plane that is integral in left-right direction. Accordingly, even if a passenger seated proximate to the dashboard advances toward the airbag, the airbag does not unnecessarily apply a partial pressure to the passenger. 
     The airbag includes the shoulder restraining portions in left and right parts thereof that project rearward upon airbag inflation. Since the shoulder restraining portions inflate in a well-balanced manner after the inner joint vicinity moves toward a passenger, a stable deployment is secured from airbag to airbag, with no anxiety of unbalanced inflation. 
     In the airbag for front passenger&#39;s seat constructed as above, moreover, it will also be appreciated that the protection portion includes a recess arranged from upper side to rear side of and between the shoulder restraining portions, and that the airbag includes a communication portion communicating the left and right shoulder restraining portions in left-right orientation, proximate to the gas inlet port, and that an opening area of the communication portion, in a section of the completely inflated airbag taken along front-rear orientation at the center of the gas inlet port, is ⅕ or greater of a projected area of a side view of the whole airbag as completely inflated. 
     With this construction, inflation gas smoothly passes through the communication portion, and prevents one of the shoulder restraining portions from inflating more than the other, so that the left and right shoulder restraining portions inflate generally evenly. If the opening area of the communication portion is less than ⅕ of the projected area of the whole airbag, it is likely that only one of the shoulder restraining portions inflates more than the other, upon airbag inflation. 
     The airbag for front passenger&#39;s seat constructed as above desirably includes a vent hole for exhausting extra inflation gas, in each of the left side wall and right side wall, each of the vent holes being located in a position within an area of the communication portion communicating the left and right shoulder restraining portions in left-right orientation, in a side view of the completely inflated airbag. 
     With this construction, the left and right shoulder restraining portions inflate and develop generally evenly. If the vent hole is located out of the area of the communication portion in a side view of the completely inflated airbag, it is likely that an even inflated condition of the both shoulder restraining portions is not maintained because of decrease of internal pressure in either one of the shoulder restraining portions. 
     Moreover, in the airbag constructed as above, it will also be appreciated that the protection portion includes a recess recessed obliquely forward and downward between the shoulder restraining portions and in the transverse center of the airbag, and that, in a sectional view of the airbag mounted on vehicle and completely inflated, taken along front-rear orientation at the center of the gas inlet port, a tangent line of a rear plane of the recess is, in major part thereof except upper and lower ends, slant, while having upper end thereof located forward and lower end thereof located rearward, so that the rear plane is directed obliquely upward for restraining a passenger&#39;s head. 
     With this construction, when the inflated airbag is thrown against a passenger, the left and right shoulder restraining portions projecting rearward firstly bump against the vicinities of passenger&#39;s shoulders, so that forward kinetic energy of the passenger is reduced. Thereafter, a head of the passenger whose shoulders are restrained by the shoulder restraining portions enters into a recess provided between the shoulder restraining portions, and then is restrained and suppressed from moving forward. When the head of the passenger bumps against the recess rear plane, since the rear plane has such construction as the tangent line of the rear plane is slant having its upper end located forward and lower end located rearward, the airbag softly receives the passenger&#39;s head while keeping the head slanted, with the smooth and slant rear plane of the recess, which is generally parallel to an upper body of the passenger advancing while leaning forward. 
     In addition, since the recess rear plane has such construction as the tangent line of the rear plane is slant in its major part while having its upper end located forward and lower end located rearward, the airbag is capable of receiving the passenger&#39;s head with a slant portion of the recess rear plane, even if a level of the head of seated passenger is changed. Accordingly, the airbag is capable of protecting the passenger&#39;s head softly regardless of passenger&#39;s physique. 
     In the above airbag for front passenger&#39;s seat, it will be appreciated that, in a sectional view of the airbag mounted on vehicle and completely inflated, taken along front-rear direction at the center of the gas inlet port, a lower end part of the recess rear plane branches off from an outline of the airbag as viewed from side, and that a branching point of the lower end part of the recess rear plane is positioned in a higher level than a lower end of an airbag portion located in higher level than the instrument panel, and in a side of a passenger with respect to the lower end of the airbag portion. 
     With this construction, a lower end portion of the inflated airbag deployed between the dashboard and a passenger&#39;s abdomen inflates in a thick manner, so that the passenger&#39;s abdomen is protected by the airbag portion in a stable manner. 
     It will also be appreciated that, in a sectional view of the airbag mounted on vehicle and completely inflated, taken along front-rear direction at the center of the gas inlet port, an upper end part of the recess rear plane branches off from an outline of the airbag, and that a branching point of the upper end part of the recess rear plane is positioned in a lower level than an upper end of the airbag, and in a side of the wind shield with respect to the airbag upper end. 
     With this construction, when the airbag is completely inflated, the recess is so formed that the rear plane in an upper end part thereof is recessed more deeply. In other words, a distance between rear planes of the shoulder restraining portions and the recess rear plane becomes greater as it goes from lower end to upper end. With this construction, when a small build passenger is seated, a head of the small build passenger is to be protected by a portion of the recess rear plane where the distance between the rear planes of the shoulder restraining portions and the recess rear plane is small. However, since a moving distance of the head from shoulders upon collision is small, in case of the small build passenger, even if the distance between the rear planes of the shoulder restraining portions and the recess rear plane is small, it is prevented that the head bumps against the airbag prior to the shoulders. That is, the head is restrained by the recess rear plane after the shoulders are restrained by the shoulder restraining portions, so that impact to the neck is reduced, and the head is softly protected. On the contrary, when a large build passenger is seated, a moving distance of his head from shoulders upon collision is greater in comparison with a case of a small build passenger. However, the head of the large build passenger is protected by a portion of the recess rear plane located upper than the portion to restrain the head of a small build passenger, where the distance between the rear planes of the shoulder restraining portions and the recess rear plane is greater. Accordingly, it is prevented that the head bumps against the airbag prior to the shoulders. That is, the head is restrained by the recess rear plane after the shoulders are restrained by the shoulder restraining portions, as in a case of the small build passenger, so that impact to the neck is reduced, and the head is softly protected. Consequently, the airbag is capable of protecting a passenger&#39;s head softly in accordance with passenger&#39;s physique. 
     It will be further appreciated that, in a sectional view of the airbag mounted on vehicle and completely inflated, taken along front-rear direction at the center of the gas inlet port, an upper end part and the lower end part of the recess rear plane branch off from the outline of the airbag as viewed from side, that the branching point of the lower end part of the recess rear plane is positioned in a higher level than the lower end of an airbag portion located in higher level than the instrument panel, and in a side of a passenger with respect to the lower end of the airbag portion, and that the branching point of the upper end part of the recess rear plane is positioned in a lower level than the upper end of the airbag, and in a side of the wind shield with respect to the airbag upper end. 
     With this construction, when the airbag is inflated and thrown against a passenger, the passenger&#39;s abdomen is protected by the lower end portion of the airbag deployed between the dashboard and a passenger&#39;s abdomen in a stable manner. In addition, the passenger&#39;s head is also protected softly by the recess, in accordance with passenger&#39;s physique, since the upper end portion of the recess rear plane is deeply recessed forward. 
     Furthermore, in the airbag for front passenger&#39;s seat constructed as above, it will be appreciated that the protection portion includes, vertically between the left and right shoulder restraining portions, a center restraining portion recessed forward for protecting a portion of a passenger between shoulders including at least a head, and that, in a condition that the airbag is mounted on vehicle and completely inflated, a disposition of the center restraining portion is adjustable in front-rear orientation. 
     With this construction, when the inflated airbag is thrown against a passenger, the left and right shoulder restraining portions projecting rearward firstly bump against the vicinities of left and right shoulders of the passenger, so that forward kinetic energy of the passenger is reduced. Thereafter, a passenger&#39;s head enters into the center restraining portion recessed between the shoulder restraining portions, and then is restrained and suppressed from moving forward by the center restraining portion. Accordingly, the airbag receives the passenger&#39;s head softly by suppressing reaction force, after kinetic energy is reduced by the shoulder restraining portions. 
     Since the disposition of the center restraining portion is adjustable in front-rear orientation in a condition that the airbag is mounted on vehicle and completely inflated, for example, if a passenger seated in front passenger&#39;s seat is of large build, the center restraining portion is disposed in a rearmost position so as to be less recessed from the shoulder restraining portions. This means that the airbag comes to have more volume when inflated, so that it may take the airbag longer time to complete inflation. However, under a circumstance that the large build passenger is seated farther rearward from the airbag, the shoulder restraining portions of the completely inflated airbag restrain left and right shoulders properly, and then the center restraining portion receives passenger&#39;s head softly. 
     When disposed in the rearmost position, the center restraining portion is more proximate to the passenger&#39;s head, in comparison with a case the center restraining portion is located in a forward position. However, since the shoulder restraining portions are inflated thick enough in left-right orientation, a forward kinetic energy of the large build passenger is absorbed by the shoulder restraining portions smoothly, so that the passenger&#39;s head is received softly, by the center restraining portion. 
     If a passenger seated in front passenger&#39;s seat is of small build, the passenger is seated more forward. The center restraining portion is disposed in a foremost position so as to be more recessed from the shoulder restraining portions. This means that the airbag comes to have less volume when inflated, and it takes the airbag less time to complete inflation. With this construction, the left and right shoulder restraining portions restrain shoulders of the small build passenger moving forward firstly, and then the center restraining portion receives a head of the small build passenger softly by its rear plane. 
     In this case, since the center restraining portion is disposed more forward, or deeply recessed, than when disposed in a rear position, the airbag properly restrains the passenger&#39;s head by the rear plane of the center restraining portion, after restraining the shoulders by the shoulder restraining portions, even if the passenger is seated proximate to the airbag. In this case, even if a passenger seated proximate to the airbag is of large build, the shoulder restraining portions restrain the shoulders of the large build passenger and absorb enough kinetic energy of the passenger because of long absorbing stroke, before protecting a head by the rear plane of the center restraining portion deeply recessed forward. Accordingly, the head of the large build passenger is received softly, too, by the rear plane of the center restraining portion. 
     The disposition of the center restraining portion may be adjusted by adjusting length of a tether which is connected to an inner edge of the center restraining portion and extends forward inside the airbag. If the airbag is provided with more than one tethers disposed along the inner edge of the center restraining portion, not only a position in front-rear direction, but also a slant angle of the center restraining portion from horizontal orientation can be adjusted by changing lengths of each of the tethers. 
     The disposition of the center restraining portion may also be adjusted by adjusting length of a string member disposed through the vertical inner edge of the center restraining portion generally all along the inner edge. When the length of the string member is adjusted, the inner edge of the center restraining portion is contracted or slacked. Accordingly, side-viewed shapes of the center restraining portions located in various positions upon airbag inflation are generally similar to one another. In addition, unlike the tether, the string member is not disposed to go across an inner space of the airbag. Accordingly, the airbag may be, at the same time, provided with a flow regulating cloth for guiding inflation gas flown in the airbag forward and rearward, since it is not likely that the flow regulating cloth engages the string member. 
     Moreover, the length of the tether or string member released into the airbag may be adjusted by a predetermined release adjusting mechanism which is connected to ends of the tether or string member taken out of the airbag, and controlled by a control circuit responding to various sensors mounted on a dashboard, a roof, a seat or the like of vehicle for monitoring seating position or weight of a passenger. When the airbag can be mounted on various kinds of vehicle in which seating position or physique of a passenger is supposed in a generally limited range, the airbag for front passenger&#39;s seat may be mounted on vehicle with a tether or a string member whose length is fixed. In this case, although the length of a tether or string member may be adjusted only until the airbag is mounted on vehicle, but not after being mounted, it is advantageous that one kind of airbag may be applied to various kinds of vehicle. 
     The second object of the present invention is attained by an airbag for front passenger&#39;s seat having following constructions: 
     The airbag is folded and housed in a top face of instrument panel in front of front passenger&#39;s seat, and upon inflow of inflation gas, the airbag protruding upward and deploying rearward of vehicle in such a manner as to occupy a space between the top face of the instrument panel and a wind shield located above the instrument panel. The airbag includes: an inlet port for introducing inflation gas, in the front end vicinity of lower side of, and in the vicinity of transverse center of, the airbag as completely inflated; and a protection portion contactable with a front seat passenger, in a rear side of the airbag as completely inflated. Upon airbag inflation, the protection portion includes: left and right shoulder restraining portions disposed generally side by side in left-right orientation, the shoulder restraining portions projecting rearward in such a manner as to contact passenger&#39;s shoulders; and a recess arranged from upper side to rear side of and between the shoulder restraining portions. The airbag includes a communication portion communicating the left and right shoulder restraining portions in left-right orientation, proximate to the gas inlet port. An opening area of the communication portion, in a section of the completely inflated airbag taken along front-rear orientation at the center of the gas inlet port, is ⅕ or greater of a projected area of a side view of the whole airbag as completely inflated. 
     With this construction, inflation gas smoothly passes through the communication portion, and prevents one of the shoulder restraining portions from inflating more than the other, so that the left and right shoulder restraining portions inflate generally evenly. If the opening area of the communication portion is less than ⅕ of the projected area of the whole airbag, it is likely that only one of the shoulder restraining portions inflates more than the other, upon airbag inflation. 
     Therefore, in the airbag for front passenger&#39;s seat constructed as above, the shoulder restraining portions as projecting portion constituting the protection portion inflate evenly, so that an approaching passenger is properly protected. 
     Moreover, in the airbag constructed as above, the protection portion includes left and right shoulder restraining portions which are disposed generally side by side in left-right orientation, and project rearward, and a recess arranged from upper side to rear side of and between the shoulder restraining portions. Accordingly, when the inflated airbag is thrown against a passenger, the left and right shoulder restraining portions projecting rearward firstly bump against the vicinities of left and right shoulders of the passenger. Thereafter, a passenger&#39;s head enters into the recess provided between the shoulder restraining portions, and then is restrained and suppressed from moving forward. Accordingly, the airbag receives the passenger&#39;s head softly by suppressing reaction force. Moreover, the opening area of the communication portion, which also constitutes the recess, is predetermined ⅕ or greater of the projected area of a side view of the whole airbag as completely inflated. With this great setting of the communication portion, the recess has a good cushioning property. Even if a head of a passenger is thrown against the recess rear plane, therefore, the head is protected by the recess rear plane properly. 
     In addition, in the airbag constructed as above, the recess is disposed from upper side to rear side of and between the shoulder restraining portions. Accordingly, even if a level of the passenger&#39;s head is changed in vertical orientation, the recess rear plane receives the head softly while suppressing reaction force from the airbag. In order to protect the passenger&#39;s head softly, the opening area of the communication portion constituting the recess is desirably less than ⅘ of the projected area of the completely inflated airbag. 
     It is desired that the airbag constructed as above is formed by sewing up edges of a plurality of predetermined shaped base cloths, and that the recess is formed by sewing up edges of base cloths constituting the left and right shoulder restraining portions. 
     With this construction, the recess is formed by sewing up edges of base cloths constituting the left and right shoulder restraining portions. Accordingly, the recess provided between the left and right shoulder restraining portions can be deeper or shallower by changing a length of the sewn portion. At the same time, an opening area of the communication portion communicating the left and right shoulder restraining portions can be changed by changing the length of the sewn portion. That is, a shape of the recess is easily changed without changing an outer contour of the airbag. 
     More specifically, it is desired that: the airbag for front passenger&#39;s seat, when completely inflated, is formed into a generally square conical shape in which a top of the square conical shape is in a front end of the airbag, and a rear side constituting the protection portion is in a bottom side of the airbag; 
     the airbag upon inflation includes: 
     an outer panel constituting areas of left and right side walls of the square conical shape, and an inner panel constituting areas from an upper side wall to a lower side wall via a rear side wall of the square conical shape, between the left and right side walls; 
     the inner panel consists of a pair of inner panel base cloths having the same shapes, the inner panel base cloths has such a construction, upon airbag inflation, as to divide the inner panel into two in left-right orientation; 
     each of the inner panel base cloths has a band shape curved in a generally C-shape, and an outer edge of each of the inner panel base cloths has generally the same shape as an outer edge of a portion of the outer panel constituting the left/right side wall; 
     the inner panel is formed by joining the outer edges of the inner panel base cloths to the outer edges of the portions of the outer panel constituting the left and right side walls, and by joining inner edges of the inner panel base cloths to each other; and 
     the recess is defined by a joint of the inner edges of the inner panel base cloths. 
     It will also be appreciated that: the airbag for front passenger&#39;s seat, when completely inflated, is formed into a generally square conical shape in which a top of the square conical shape is in a front end of the airbag, and a rear side constituting the protection portion is in a bottom side of the airbag; 
     the airbag upon inflation includes: 
     an upper panel constituting areas of left and right side walls and an area from upper side wall to rear side wall, of the square conical shape, and a lower panel constituting an area of a lower side wall of the square conical shape; 
     the upper panel consists of a pair of upper panel base cloths having the same shapes, the upper panel base cloths has such a construction, upon airbag inflation, as to divide the upper panel into two in left-right orientation; 
     the upper panel is formed by joining inner edges of the upper panel base cloths to each other; and 
     the recess is defined by a joint of the inner edges of the upper panel base cloths. 
     It will also be appreciated that: the airbag for front passenger&#39;s seat, when completely inflated, is formed into a generally square conical shape in which a top of the square conical shape is in a front end of the airbag, and a rear side constituting the protection portion is in a bottom side of the airbag; 
     the airbag upon inflation includes: 
     a front panel constituting areas of left and right side walls and an area from upper side wall to lower side wall, of the square conical shape, and a rear panel constituting an area of a rear side wall of the square conical shape; 
     the rear panel consists of a pair of rear panel base cloths having the same shapes, the rear panel base cloths has such a construction, upon airbag inflation, as to divide the rear panel into two in left-right orientation; 
     the rear panel is formed by joining inner edges of the rear panel base cloths to each other; and 
     the recess is defined by a joint of the inner edges of the rear panel base cloths. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic vertical section of an airbag device for front passenger&#39;s seat employing an airbag according to a first embodiment of the present invention, taken along front-rear orientation of vehicle; 
         FIG. 2  is a perspective view of the airbag of the first embodiment inflating by itself, as viewed from front; 
         FIG. 3  is a perspective view of the airbag of  FIG. 2  as viewed from rearward; 
         FIG. 4  is a sectional view of the airbag of  FIG. 2 , taken along front-rear direction; 
         FIG. 5  is a sectional view taken along V-V in  FIG. 4 ; 
         FIG. 6  illustrates constituent parts of the airbag of  FIG. 2  by plan views; 
         FIG. 7  is a schematic side view of the airbag of  FIG. 2  lapped in transverse direction and developed flatly; 
         FIG. 8  illustrates the airbag of  FIG. 2  having gone through a preparatory folding step, as viewed from side of a gas inlet port; 
         FIG. 9  illustrates the airbag of  FIG. 8  as viewed from side of a protection portion; 
         FIG. 10  is an end view taken along line X-X of  FIG. 8 ; 
         FIG. 11  is an end view taken along line XI-XI of  FIG. 8 ; 
         FIGS. 12A to 12C  and  13 A to  13 C illustrate folding process of the airbag of  FIG. 2  after the preparatory folding step; 
         FIG. 14  illustrates the airbag of  FIG. 2  in service as viewed from rearward of vehicle, the airbag being completely inflated; 
         FIG. 15  schematically illustrates the airbag of  FIG. 14  as viewed from upper side of vehicle; 
         FIG. 16  schematically illustrates the airbag of  FIG. 14  as viewed from side of vehicle; 
         FIG. 17  is a perspective view of an airbag for front passenger&#39;s seat according to a second embodiment of the present invention, the airbag being inflated by itself and viewed from forward of vehicle; 
         FIG. 18  is a perspective view of the airbag of  FIG. 17 , as viewed from rearward of vehicle; 
         FIG. 19  is a sectional view of the airbag of  FIG. 17 , taken along front-rear orientation; 
         FIG. 20  illustrates constituent parts of the airbag of  FIG. 17  by plan views; 
         FIGS. 21 and 22  schematically illustrate the airbag of  FIG. 17  in service as viewed from side of vehicle, the airbag being completely inflated; 
         FIG. 23  is a schematic vertical section of an airbag device for front passenger&#39;s seat employing an airbag according to a third embodiment of the present invention, taken along front-rear orientation of vehicle; 
         FIG. 24  is an enlarged schematic view of the airbag device of  FIG. 23 ; 
         FIG. 25  is a schematic vertical section of a release adjuster employed with the airbag of the third embodiment, taken along XXV-XXV of  FIG. 24 ; 
         FIG. 26  is a perspective view of the airbag of the third embodiment, as inflated by itself and viewed from forward of vehicle; 
         FIG. 27  is a sectional view of the airbag of  FIG. 26  taken along front-rear orientation; 
         FIG. 28  is a schematic section of the airbag of  FIG. 26  taken along XXVIII-XXVIII of  FIG. 27 ; 
         FIG. 29  illustrates constituent parts of the airbag of  FIG. 26  by plan views; 
         FIG. 30  schematically illustrates the airbag of  FIG. 26  in service as viewed from upper side of vehicle, the airbag being completely inflated; 
         FIG. 31  is a schematic view of the airbag of  FIG. 30  as viewed from side of vehicle; 
         FIG. 32  is a schematic view of the airbag of  FIG. 26  in service as viewed from upper side of vehicle, in a state that a position of a center restraining portion in front-rear orientation is adjusted; 
         FIG. 33  is a schematic view of the airbag of  FIG. 32  as viewed from side of vehicle; 
         FIG. 34  is a schematic vertical section of an airbag device for front passenger&#39;s seat employing a modification of the airbag of the third embodiment, taken along front-rear orientation of vehicle; 
         FIG. 35  is an enlarged schematic section of the airbag device of  FIG. 34  taken along front-rear orientation of vehicle; 
         FIG. 36  is a schematic vertical section of a release adjuster employed with the modified airbag, taken along XXXVI-XXXVI of  FIG. 35 ; 
         FIG. 37  is a sectional view of the modified airbag inflated by itself, taken along front-rear orientation; 
         FIG. 38  is a schematic section of the airbag of  FIG. 37 , taken along XXXVIII-XXXVIII of  FIG. 37 ; 
         FIG. 39  is a schematic view of the airbag of  FIG. 37  as viewed from upper side of vehicle, in a state that a position of a center restraining portion in front-rear orientation is adjusted; 
         FIG. 40  is a schematic view of the airbag of  FIG. 39  as viewed from side of vehicle; 
         FIG. 41  is a perspective view of an airbag according to a fourth embodiment of the present invention as inflated by itself and viewed from forward; 
         FIG. 42  is a perspective view of the airbag of  FIG. 41 , as viewed from rearward; 
         FIG. 43  is a sectional view of the airbag of  FIG. 41 , taken along front-rear orientation; 
         FIG. 44  illustrates constituent parts of the airbag of  FIG. 41  by plan views; 
         FIG. 45  illustrates the airbag of  FIG. 41  in service as viewed from rearward of vehicle, the airbag being completely inflated; 
         FIG. 46  schematically illustrates the airbag of  FIG. 45  as viewed from side of vehicle; 
         FIG. 47  is a perspective view of an airbag according to a fifth embodiment of the present invention as inflated by itself and viewed from forward; 
         FIG. 48  is a perspective view of the airbag of  FIG. 47  as viewed from rearward; 
         FIG. 49  is a sectional view of the airbag of  FIG. 47  taken along front-rear orientation; 
         FIG. 50  illustrates constituent parts of the airbag of  FIG. 47  by plan views; 
         FIG. 51  illustrates the airbag of  FIG. 47  in service as viewed from rearward of vehicle, the airbag being completely inflated; and 
         FIG. 52  schematically illustrates the airbag of  FIG. 51  as viewed from side of vehicle. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention are now described below with reference to the accompanying drawings. However, the invention is not limited to the embodiments disclosed herein. All modifications within the appended claims and equivalents relative thereto are intended to be encompassed in the scope of the claims. Up-down, front-rear, and left-right directions in this specification correspond to up-down, front-rear, and left-right directions of a vehicle being steered straight forward. 
     Firstly, a first embodiment of the present invention is described, by which the first and second object of the present invention are attainable. 
       FIG. 1  illustrates an airbag  15  for front passenger&#39;s seat used for an airbag device M 1  for front passenger&#39;s seat. The airbag device M 1  for front passenger&#39;s seat is a top-mount type that is disposed in interior of a top face  2  of instrument panel  1 . The airbag device M 1  includes a folded airbag  15 , an inflator  8  for supplying the airbag  15  with inflation gas, a case  6  for housing and holding the airbag  15  and the inflator  8 , a retainer  11  for attaching the airbag  15  to the case  6 , and an airbag cover  10  for covering the folded airbag  15 . 
     The airbag cover  10  is integral with the dashboard  1  made from synthetic resin, and is adapted to open two front and rear doors  10   a  and  10   b  when pushed by the inflating airbag  15 . The airbag cover  10  includes a joint wall  10   c  by which the airbag cover  10  is attached to the case  6 . The joint wall  10   c  is arranged around the doors  10   a  and  10   b  of the airbag cover  10 . 
     The inflator  8  includes a body portion  8   a  having a generally columnar shape and provided with gas discharge ports  8   b , and a flange  8   c  for attaching the inflator  8  to the case  6 . 
     The case  6  is made of sheet metal into a generally rectangular parallelepiped shape, and has a rectangular opening at the top. The case  6  includes a bottom wall  6   a  of a generally rectangular plate shape, and a side wall  6   b  extending upward from outer edge of the bottom wall  6   a . The inflator  8  is set in an insert hole of the bottom wall  6   a  from lower side. The side wall  6   b  retains the joint wall  10   c  of the airbag cover  10 . The case  6  is further provided with unillustrated brackets, in the bottom wall  6   a , for attachment of the case  6  to vehicle body. 
     The airbag  15  and the inflator  8  are secured to the case  6  by attaching an annular retainer  11  inside the airbag  15  such that bolts  11   a  of the retainer  11  are put through the airbag  15 , the flange  8   c  of the inflator  8 , and the case bottom wall  6   a , and then fastened into nuts  12 . 
     Referring to  FIGS. 1 to 5 , the airbag  15  includes an airbag body  16  and a flow regulating cloth  29  disposed inside the airbag body  16 . The airbag body  16  is formed into a generally square conical shape whose top is in a front end of the airbag body  16 . The airbag body  16  includes an upper side wall  16   a  and a lower side wall  16   b  arranged generally along left-right direction in upper and lower sides, a left side wall  16   c  and a right side wall  16   d  arranged generally along front-rear direction in left and right sides, and a rear wall  16   e  arranged generally along left-right direction to confront a passenger, in such a manner as to connect the upper side wall  16   a  and the lower side wall  16   b . The airbag body  16  includes a protection portion  25  to be arranged in a rear side to face toward a passenger upon airbag inflation, and a vehicle body side portion  17  to be arranged between the dashboard  1  and a wind shield  4  forward of the protection portion  25  upon airbag inflation. The vehicle body side portion  17  has a generally cylindrical shape closed at a front end thereof. The airbag body  16  further includes a round gas inlet port  19  for introducing inflation gas, in the vicinity of transverse center of the vehicle body side portion  17  and proximate to a front end of the lower side wall  16   b  of the airbag body  16  as completely inflated. In a periphery  18  of the inlet port  19  are mounting holes  20  for inserting the bolts  11   a  of the retainer  11  to attach the inlet port periphery  18  to the bottom wall  6   a  of the case  6 . 
     The protection portion  25  includes shoulder restraining portions  26 L and  26 R, as projecting portions, disposed side by side in left-right direction, and a recess  27  recessed from upper side to rear side between the left and right shoulder restraining portions  26 L and  26 R. Each of the shoulder restraining portions  26 L and  26 R is arranged vertically and project rearward. In the illustrated embodiment, rise of the left and right shoulder restraining portions  26 L and  26 R, and recess of the recess  27  continue forward from the rear side wall  16   e  of the airbag body  16 , in such a manner as to enter within areas of the upper and lower side walls  16   a  and  16   b , up to the vicinity of the gas inlet port  19  of the vehicle body side wall  17 , but this unevenness stops in a lower part  39  of a later-described first base cloth  38 , as shown in  FIG. 2 . 
     Referring to  FIGS. 4 and 5 , the flow regulating cloth  29  located inside the airbag body  16  is arranged to cover the gas inlet port  19  from upper side. The flow regulating cloth  29  is formed into a generally cylindrical shape opened at front and rear ends so as to redirect inflation gas G flown in via the inlet port  19  forward and rearward. In the airbag  15 , more specifically, the inflation gas G flown in via the inlet port  19  is supplied into the airbag body  16  from front and rear openings  30 A and  30 B of the flow regulating cloth  29 . In the flow regulating cloth  29 , as shown in  FIGS. 1 ,  15  and  16 , an upper part of the front and rear openings  30 A and  30 B are located in higher level than the top face  2  of the dashboard  1 , upon deployment of the airbag  15 . The flow regulating cloth  29  has a greater dimension than front-rear, and left-right dimension of the gas inlet port  19 , but is not so great as to reach an inner edge of a later-described communication port  22 . A sectional shape of the flow regulating cloth  29  taken along front-rear direction at the center vicinity of the inlet port  19  is a curvature bulging upward away from the inlet port  19 . The flow regulating cloth  29  further includes through holes  31  adapted to release inflation gas supplied from the inlet port  19 . A total of opening areas of the through holes  31  is smaller than an opening area of the opening  30 A/ 30 B. In the illustrated embodiment, the through holes  31  are located in two positions symmetric with respect to a center of the inlet port  19 , as shown in  FIGS. 4 and 5 . The through holes  31  help stabilize orientation of the front and rear openings  30 A and  30 B, and further stabilize direction of the inflation gas G flowing into the airbag body  16 , upon airbag deployment, by releasing a small portion of the inflation gas G flown in via the inlet port  19 . 
     The flow regulating cloth  29  is made of a material  50  for the flow regulating cloth shown in  FIG. 6 . The material  50  includes a generally rectangular joint portion  51  and extensions  52  extending from left and right sides of the joint portion  51 . The joint portion  51  includes an opening  51   a  correspondent to the inlet port  19 , and holes  51   b  correspondent to the mounting holes  20 , and is sewn to the lower part  39  of the first base cloth  38  at its circumference. The extensions  52  are sewn up at edges  52   a  thereof apart from the joint portion  51 . The through holes  31  are formed in left and right sides of the opening  51   a  in the extensions  52 , the positions being symmetric with respect to the opening  51   a.    
     The airbag body  16  is formed by joining edges of predetermined shaped base cloths. The airbag body  16  includes an outer panel  35  constituting the left and right side walls  16   c  and  16   d , and a front part of the lower side wall  16   b , and an inner panel  36  constituting the upper and rear side walls  16   a  and  16   e , and a rear part of the lower side wall  16   b . In the illustrated embodiment, the airbag body  16  is formed of a first base cloth  38  and a pair of second base cloths  43 L and  43 R, as inner panel base cloth, having the same shapes. The first base cloth  38  constitutes the outer panel  35 , while the second base cloths  43 L and  43 R constitute the inner panel  36 . 
     The first base cloth  38  has a laterally symmetric shape proximate to a figure of a butterfly spreading its wings. The first base cloth  38  includes a generally rectangular lower part  39  constituting the periphery  18  of the gas inlet port  19  in the vehicle body side portion  17 , and left and right portions  40  and  41 , each of which having a generally triangular plate shape, arranged in such a manner as to extend left and rightwards from the lower part  39 . The lower part  39  makes a front part of the lower side wall  16   b  of the airbag body  16  as completely inflated, which is the vicinity of the gas inlet port  19 . The left and right portions  40  and  41  mainly constitute the left and right side walls  16   c  and  16   d  of the airbag body  16  as completely inflated. Portions in the vicinity of outer edges  40   a  and  41   a  of the left and right portions  40  and  41  constitute outer wall portions  26   b  located toward transverse ends than projected tops  26   a  of the shoulder restraining portions  26 L and  26 R, respectively, as shown in  FIGS. 2 and 5 . In the illustrated embodiment, the left and right portions  40  and  41  are symmetric to each other with respect to a line running through the center of the inlet port  19 . 
     Referring to  FIGS. 2 ,  3  and  5 , the second base cloths  43 L and  43 R are arranged in such a manner as to divide an area of the inner panel  36  into two in left-right direction, upon airbag inflation. In the illustrated embodiment, in the airbag body  16  as completely inflated, the second base cloths  43 L and  43 R constitute the upper and rear side walls  16   a ,  16   e  and a rear part of the lower side wall  16   b . The second base cloths  43 L and  43 R also constitute inner wall portions  26   c  that are located toward transverse center than the projected tops  26   a  of the shoulder restraining portions  26 L and  26 R. Each of the second base cloths  43 L and  43 R has a band shape curved in a generally C-shape. In the illustrated embodiment, an outer edge portion  43   d  of each of the second base cloths  43 L and  43 R has generally the same shape as a portion of the edge  40   a / 41   a  of the left/right portion  40 / 41  in the first base cloth  38  except a root side edge  40   b / 41   b . Moreover, inner edge portions  43   a  formed in inner circumferences of the second base cloths  43 L and  43 R provide a leading end  27   a  of the recess  27  recessed inward of the airbag body  16 , and also an edge of a communication port  22  that communicates the left and right shoulder restraining portions  26 L and  26 R. 
     The shoulder restraining portions  26 L and  26 R and the recess  27  in the protection portion  25  are formed by sewing up edges of, the left and right portions  40  and  41  of the first base cloth  38 , and the second base cloths  43 L and  43 R. A sewn portion  33 L, as outer joint, formed by sewing up the edge  40   a  of the left portion  40  in the first base cloth  38  and the outer edge  43   d  of the second base cloth  43 L, and a sewn portion  33 R, also as outer joint, formed by sewing up the edge  41   a  of the right portion  41  in the first base cloth  38  and the outer edge  43   d  of the second base cloth  43 R provide, respectively, the projected tops  26   a  of the shoulder restraining portions  26 L and  26 R. The vicinity of a sewn portion  34 , as inner joint, formed by sewing up the inner edges  43   a  of the second base cloths  43 L and  43 R provides the leading end  27   a  of the recess  27 . 
     In interior side of the airbag body  16 , a communication port  22  is provided in the vicinity of the recess leading end  27   a . The communication port  22  communicates the shoulder restraining portions  26 L and  26 R in left-right direction, and is defined by the sewn portion  34 , or the leading end  27   a  of the recess  27 , formed by sewing up the inner edges  43   a  of the second base cloths  43 L and  43 R, and the lower part  39  of the first base cloth  38 . The communication port  22  ranges from lower side of the protection portion  25  to lower side of the vehicle body side portion  17 , as shown in  FIG. 4 . 
     When the airbag body  16  is completely inflated, an opening plane of the communication port  22  is arranged along front-rear direction in generally transverse center of the airbag body  16 . An opening area S 1  of the communication port  22  in a section taken along front-rear direction generally at the center of the gas inlet port  19 , in an completely inflated condition of the airbag body  16  or the airbag  15 , is predetermined ⅕ or greater of a projected area S 2  of a side view of the whole airbag body  16  or the whole airbag  15  as completely inflated, as shown in  FIG. 4 . In the illustrated embodiment, the opening area S 1  of the communication port  22  is generally half of the projected area S 2  of the completely inflated airbag  15 . In order to protect a passenger&#39;s head softly, the opening area S 1  of the communication port  22  is desirably less than ⅘ of the projected area S 2  of the completely inflated airbag  15 . If the opening area S 1  of the communication port  22  is ⅘ or greater of the projected area S 2  of the completely inflated airbag  15 , projecting amount of the shoulder restraining portions  26 L and  26 R, i.e., recessing amount of the recess  27 , becomes relatively small, which may cause failure in protecting the passenger&#39;s head softly. 
     The airbag body  16  is provided with a vent hole  23  for exhausting extra inflation gas in each of the left and right side walls  16   c  and  16   d . As shown in  FIG. 4 , each of the vent holes  23  is located in a position within an area of the communication port  22  in a side view of the completely inflated airbag body  16 . 
     The airbag body  16  is further provided with reinforcing cloths  45  and  46  for reinforcing the inlet port periphery  18 , reinforcing cloths  47 L and  47 R for reinforcing the sewn portions  34 , and a protection cloth  48  for protecting the inlet port periphery  18 . The reinforcing cloth  45  is formed into a shape that covers a generally entire area of inner surface of the lower part  39  of the first base cloth  38 . Flap portions  45   a  of the reinforcing cloth  45 , which have such a shape as to project left and rightward, are sewn to the vicinity of the sewn portions  33 L and  33 R, respectively, at leading ends  45   b  thereof. Each of the reinforcing cloths  46  has a generally round shape. Although the airbag  15  in the foregoing embodiment has two reinforcing cloths  46 , number of the reinforcing cloth  46  may be varied according to output of the inflator  8 . Each of the reinforcing cloths  47 L and  47 R has a shape curved in a generally C-shape corresponding to the inner edge  43   a  of the second base cloth  43 L/ 43 R, and is adapted to cover an entire area of the inner edge  43   a  of the second base cloth  43 L/ 43 R for reinforcing the sewn portion  34 . The protection cloth  48  has a generally rectangular shape extending front and rearwards of the gas inlet port  19 , and is applied to inner surface of the airbag body  16  in order to prevent the inflation gas G discharged from the inflator  8  from hitting sewn portions  54  and  55  located proximate to the inlet port  19 , or sewn portions sewing up the lower part  39  of the first base cloth  38  and the second base cloths  43 L and  43 R, and so on, directly. The protection cloth  48  is sewn to the vicinity of the sewn portions  33 L and  33 R at a plurality of positions in left and right edges thereof. In the illustrated embodiment, the protection cloth  48  is sewn to the vicinity of the sewn portions  33 L and  33 R at six positions in front and rear ends  48   a ,  48   b , and in positions  48   c  between the inlet port  19  and the front end  48   a , as shown in  FIG. 6 . 
     In the foregoing embodiment, the first and second base cloths  38 ,  43 L and  43 R, the reinforcing cloths  45 ,  46 ,  47 L and  47 R, the protection cloth  48 , and the flow regulating cloth material  50  are made from flexible woven fabric of polyester, polyamide or the like. The woven fabric is not coated by coating agent such as silicone, or the like. 
     Manufacturing of the airbag  5  is now described. Firstly, the reinforcing cloth  45 , the flow regulating cloth material  50 , and the reinforcing cloths  46  are lapped over the flatly developed first base cloth  38  in this order, and sewn to the first base cloth  38  at a position around the mounting holes  20  in the periphery  18  of the gas inlet port  19 , and at a position running along an edge of the joint portion  51  of the flow regulating cloth  50  by sewing yarn, so that sewn portions  54  and  55  are provided. Subsequently, the protection portion  48  is lapped over the reinforcing cloth  46 , and sewn thereto at a position between the inlet port  19  and the mounting holes  20  in a generally round shape, thereby a sewn portion  56  is provided. Thereafter, the gas inlet port  19  and the mounting holes  20  are formed by punching work. Subsequently, the edges  52   a  of the extensions  52  in the flow regulating cloth material  50  are sewn up together by sewing yarn in an arcuate shape, so that the flow regulating cloth  29  is formed into a predetermined shape. Although the punching work for providing the inlet port  19  and the mounting holes  20  are applied after the reinforcing cloths  45 ,  46 , the protection cloth  48  and the flow regulating cloth material  50  are sewn to the first base cloth  38 , each of the reinforcing cloths  45 ,  46 , the protection cloth  48  and the flow regulating cloth material  50  may be provided with apertures constituting the inlet port and mounting holes in advance. 
     Thereafter, the second base cloths  43 L and  43 R are lapped with each other, and the reinforcing cloths  47 L and  47 R are applied in such a manner as to put the inner edges  43   a  of the second base cloths  43 L and  43 R therebetween. Then the inner edges  43   a  are sewn up together with the reinforcing cloths  47 L and  47 R, so that a sewn portion  34  is provided. Subsequently, with stitch allowances of the inner edges  43   a  kept inside, the second base cloths  43 L and  43 R are opened so that the front edges  43   b  of the second base cloths  43 L and  43 R are disposed in series generally straightly. Then the front edges  43   b  thus disposed straightly are sewn to a front edge  39   a  of the lower part  39  in the first base cloth  38  and to a front edge  45   c  of the reinforcing cloth  45 . Likewise, rear edges  43   c  of the second base cloths  43 L and  43 R also disposed straightly are sewn to a rear edge  39   b  of the lower part  39  in the first base cloth  38  and to a rear edge  45   d  of the reinforcing cloth  45 . Then front and rear left edges  39   c  of the lower part  39  are sewn to the root side portions  40   b  of the edge  40   a  in the left portion  40 , while right edges  39   d  of the lower part  39  are sewn to the root side portions  41   b  of the edge  41   a  in the right portion  41 . Thereafter, the sewn portion  33 L is formed by sewing up the edge  40   a  of the left portion  40  and the outer edge  43   d  of the second base cloth  43 L, while the sewn portion  33 R is formed by sewing up the edge  41   a  of the right portion  41  and the outer edge  43   d  of the second base cloth  43 R. Subsequently, the leading ends  45   b  of the reinforcing cloth  45  and part of the protection cloth  48 , or portions  48   a ,  48   b  and  48   c  in the left and right edges of the protection cloth  48 , are sewn to the vicinity of the sewn portions  33 L and  33 R. If then the airbag  15  is reversed inside out utilizing the gas inlet port  19  so that stitch allowances may not appear on surface, the airbag  15  is complete. If it is difficult to reverse the airbag  15  from the inlet port  19 , the extensions  52  of the flow regulating cloth material  50  may be taken out of the inlet port  19  and sewn up at the edges  52   a  after the airbag body  16  is reversed inside out. 
     In the airbag  15 , the inner panel  36  is formed by a pair of the second base cloths  43 L and  43 R having the generally same shape. Moreover, the outer edge portion  43   d  of each of the second base cloths  43 L and  43 R has generally the same shape as the edge  40   a / 41   a  of the left/right portion  40 / 41  in the first base cloth  38  except the root side portion  40   b / 41   b . Accordingly, sewing positions in the edges of the base cloths  38 ,  43 L and  43 R easily match one another only by lapping the base cloths  38 ,  43 L and  43 R one on another, which facilitates sewing work of the airbag  15 . 
     To mount the airbag  15  thus manufactured on vehicle, the airbag  15  is firstly folded up with the retainer  11  arranged inside thereof so that the bolts  11   a  protrude from the mounting holes  20 . Folding process of the airbag  15  includes preparatory folding step, transverse folding step, and vertical folding step. 
     The preparatory folding step provides a preparatorily folded airbag  58  shown in  FIGS. 8 to 11 . The preparatorily folded airbag  58  has a generally flat shape in which the projected tops  26   a  of the left and right shoulder restraining portions  26 L and  26 R are opened left and rightwards with respect to the sewn portion  34 , and the sewn portion  34  is arranged in front-rear direction while confronting the gas inlet port  19 . More specifically, the sewn portion  34  is disposed in generally entire circumference of the preparatorily folded airbag  58  except the periphery  18  of the inlet port  19 , i.e., a portion defined by the lower part  39  of the first base cloth  38 , along front-rear direction and in generally transverse center of the preparatorily folded airbag  58 , as shown in  FIGS. 8 and 9 . 
     More specifically, as shown in  FIGS. 8 and 9 , in the preparatorily folded airbag  58 , the left and right portions  40  and  41  of the outer panel  35  are folded on valley folds CL 1 , CL 2 , CR 1 , and CR 2  extending along front-rear direction. At this time, upper portions  43   e  of the second base cloths  43 L and  43 R are flatly developed, and this developed portion  59  is arranged such that a transverse center portion  59   a  in the vicinity of upper end thereof confronts the gas inlet port  19 . In the illustrated embodiment, as shown in  FIG. 7 , supposing that the airbag  15  is flatly developed with the projecting tops  26   a  of the shoulder restraining portions  26 L and  26 R lapped in transverse direction, the folds CL 1  and CL 2  are formed to run generally in parallel to a section of an opening plane of the gas inlet port  19  taken along front-rear direction, through a rearmost point  34   a  of the sewn portion  34 , i.e., a point in the sewn portion  34  most distant from the opening plane of the inlet port  19  in a direction perpendicular to the opening plane of the inlet port  19 . As shown in  FIGS. 8 to 10 , the folds CL 1  and CR 1  are so disposed proximate to each other as to confront the gas inlet port  19 . That is, the valley folds CL 1  and CR 1  of the preparatorily folded airbag  58  are formed below the developed portion  59 , as shown in  FIG. 10 , in the left and right portions  40  and  41  of the first base cloth  38 , respectively, to run generally in parallel to the opening plane of the gas inlet port  19  in a section of the inlet port  19  taken along front-rear direction, so that the developed portion  59  is generally parallel to the opening plane of the inlet port  19 . As shown in  FIGS. 10 and 11 , there is a greater distance between the folds CL 2  and CR 2  than that between the folds CL 1  and CR 1 , and the folds CL 2  and CR 2  are more elongated in generally front-rear direction than the folds CL 1  and CR 1 . The folds CL 2  and CR 2  are located proximate to the inlet port  19 . The folds CL 1  and CR 1 , and the folds CL 2  and CR 2  are generally laterally symmetric with respect to the inlet port  19 . 
     As shown in  FIGS. 8 and 9 , portions in the vicinity of lower end  58   b  of the preparatorily folded airbag  58  are folded in on folds CHL and CHR extending along generally transverse direction. The folds CHL and CHR are also generally laterally symmetric with respect to the inlet port  19 . In the preparatorily folded airbag  58 , moreover, in a supposed airbag  15  flatly developed with the projecting tops  26   a  of the shoulder restraining portions  26 L and  26 R lapped in transverse direction, as shown in  FIG. 7 , a portion  59   a  of the developed portion  59  located in a side of the gas inlet port  19  with respect to the rearmost point  34   a  in the sewn portion  34 , and in a higher level than the rearmost point  34   a  is arranged to confront the inlet port  19 . The preparatorily folded airbag  58  has a generally laterally symmetric shape with respect to the inlet port  19 . 
     Referring to  FIG. 2 , the preparatory folding is conducted by holding a front end vicinity portion  16   aa  in transverse center of the upper side wall  16   a , and a portion  16   ba  in a center in front-rear and left-right directions of the lower side wall  16   b , of the airbag body  16 , and pulling and separating the held portions  16   aa  and  16   ba  in front-rear direction so as to provide the folds CL 2  and CR 2 , while holding rear end vicinity portions  26   d  in the projecting tops  26   a  of the shoulder restraining portions  26 L and  26 R and opening the shoulder restraining portions  26 L and  26 R left and rightwards of the sewn portion  34  in a flattening manner so as to provide the folds CL 1  and CR 1 , and then by folding in lower end portions on the folds CHL and CHR. The held portions  16   aa  and  16   ba  define front and rear ends  58   a  and  58   b  of the preparatorily folded airbag  58 , respectively. 
     Subsequently, as shown in  FIGS. 12A ,  12 B,  12 C,  13 A and  13 B, the transverse folding is applied to the preparatorily folded airbag  58 . More specifically, front and rear portions  61  and  62  of the inlet port  19  in the preparatorily folded airbag  58  are folded on folds extending along left-right direction such that ends  61   a  and  62   a  are brought closer to the inlet port  19 . In the illustrated embodiment, the rear portion  61  is rolled toward the lower side wall  16   b  from the rear end  61   a , and is placed on a back side of the inlet port  19 , as shown in  FIGS. 12B and 12C . The front portion  62  is rolled toward the rear wall  16   e  from the front end  62   a , and is placed over a rolled portion  63  of the rear portion  61 , as shown in  FIGS. 12C ,  13 A and  13 B. 
     Then the vertical folding is applied, as shown in  FIGS. 13B and 13C . A left portion  65  and right portion  66  of the inlet port  19  in the transversely-folded airbag  64  are folded on folds extending along front-rear direction such that ends  65   a  and  66   a  are brought close to the inlet port  19 . In the illustrated embodiment, the left and right portions  65  and  66  are bellows-folded so that the ends  65   a  and  66   a  are brought close to the inlet port  19  and placed on a back side of the inlet port  19 . 
     When the folding of the airbag  15  is completed by the vertical folding, the folded-up airbag  15  is wrapped by a breakable wrapping sheet  14  (refer to  FIG. 1 ) to keep the folded-up configuration. Then the folded-up airbag  15  is placed on the bottom wall  6   a  of the case  6  by putting the bolts  11   a  of the retainer  11  through the bottom wall  6   a . Subsequently, the body  8   a  of the inflator  8  is set in the case  6  from lower side of the bottom wall  6   a , while the bolts  11   a  protruded downward from the bottom wall  6   a  are inserted through the flange  8   c  of the inflator  8 . Thereafter, by fastening the bolts  11   a  protruded from the flange  8   c  of the inflator  8  into nuts  12 , the folded-up airbag  15  and the inflator  8  are attached to the bottom wall  6   a  of the case  6 . 
     Then if the side wall  6   b  of the case  6  is retained by the joint wall  10   c  of the airbag cover  10  in the dashboard  1  having been mounted on vehicle, and the unillustrated brackets of the case  6  are fixed to predetermined portions of vehicle body, the airbag device M 1  for front passenger&#39;s seat is mounted on vehicle. 
     After mounting the airbag device M 1  on vehicle, when inflation gas G is discharged from the gas discharge ports  8   b  of the inflator  8  upon frontal collision of vehicle, the airbag body  16  inflates. The airbag body  16  breaks the wrapping sheet  14 , and further pushes and opens the doors  10   a  and  10   b  of the airbag cover  10 , as indicated by double-dotted lines in  FIG. 1 . Then the airbag body  16  protrudes upward from an opening provided by the opening of the doors  10   a  and  10   b  of the airbag cover  10 , and deploys rearward of vehicle in such a manner as to occupy a space between the dashboard top face  2  and the windshield  4 , as indicated by double-dotted lines in  FIG. 1  and as shown in  FIGS. 14 to 16 . Thus the airbag body  16  completes inflation. 
     In the airbag  15  for front passenger&#39;s seat according to the first embodiment of the present invention, the protection portion  25  includes, in a portion ranging from upper side to rear side in a completely inflated condition, the shoulder restraining portions  26 L and  26 R that are disposed side by side in generally left-right direction and continuously project upward and then rearward. That is, the protection portion  25  inflates in such a shape as is recessed in a transverse center thereof or between the shoulder restraining portions  26 L and  26 R. With this construction, when the inflated airbag  15  is thrown against a passenger MP, the left and right shoulder restraining portions  26 L and  26 R projecting rearward firstly bump against the vicinities of left and right shoulders MS of the passenger MP, as shown in  FIGS. 15 and 16 , so that forward kinetic energy of the passenger MP is reduced. Thereafter, a head MH of the passenger MP whose shoulders MS are restrained by the shoulder restraining portions  26 L and  26 R enters into the recess  27  provided between the shoulder restraining portions  26 L and  26 R, and then is restrained and suppressed from moving forward. Accordingly, the airbag  15  is capable of receiving the head MH of the passenger MP by suppressing reaction force from the airbag  15 , in a condition that kinetic energy is reduced by the shoulder restraining portions  26 L and  26 R. 
     Therefore, the airbag  15  of the first embodiment is capable of, when completely inflated and thrown against the head MH of the passenger MP, protecting the head MH properly by suppressing reaction force, thereby attaining the first object of the present invention. 
     In the meantime, in the airbag  15 , since each of the shoulder restraining portions  26 L and  26 R is arranged from upper side to rear side of the inflated airbag body  16  in a continuously projecting manner, the recess  27  provided between the shoulder restraining portions  26 L and  26 R is also arranged continuously from upper end of the protection portion  25  generally vertically. Accordingly, even if a position of the head MH of the passenger MP varies in vertical orientation according to a build or sitting posture of the passenger MP, the airbag  15  receives the head MH softly while suppressing reaction force. 
     In the airbag  15 , the sewn portion  34  sewing up the inner edges  43   a  of the second base cloths  43 L and  43 R, which constitute the inner panel  36 , is arranged generally all over the circumference of the airbag body  16  in generally vertical direction, and in a generally transverse center of the airbag body  16  as inflated. Since the inner edge  43   a  of the second base cloth  43 L/ 43 R defining the sewn portion  34  has a shorter length than the outer edge  43   d  of the second base cloth  43 L/ 43 R, the sewn portion  34  is positioned inward of an outline, or the rear wall  16   e , of the airbag body  16  as viewed from side, as shown in  FIG. 4 . Accordingly, the whole base cloths of the airbag body  16  is regulated in developing direction by the sewn portion  34  when developed and inflated, so that the rear wall  16   e  to be deployed toward passenger is prevented from protruding toward passenger upon airbag inflation, and a shape of the completely inflated airbag body  16  is regulated. As a result, the airbag body  16  no longer needs a tether or the like which would pull the rear wall  16   e  forward i.e., in a direction opposite to passenger and regulate the shape of the airbag body  16  as completely inflated, so that number of parts of the airbag  15  is reduced. 
     Moreover, the airbag  15  of the first embodiment includes the flow regulating cloth  29  having a generally cylindrical shape. The flow regulating cloth  29  is located inside the airbag body  16 , and is arranged to cover the gas inlet port  19  from upper side. Since the flow regulating cloth  29  is so opened at front and rear ends so as to redirect inflation gas G flown in via the inlet port  19  forward and rearward, the inflation gas G flown in via the inlet port  19  is supplied into the airbag body  16  from front and rear openings  30 A and  30 B of the flow regulating cloth  29  along front-rear direction, upon airbag inflation, as shown in  FIGS. 4 and 16 . That is, in the airbag  15 , inflation gas G flows into the airbag body  16  along front-rear direction, i.e., along the dashboard top face  2 , so that a lower part of the airbag body  16 , especially rear lower part of the airbag body  16  is developed along the dashboard  1 . As a result, the airbag  15  is prevented from unnecessarily protruding toward the passenger MP. 
     In the airbag  15  of the first embodiment, moreover, the flow regulating cloth  29  includes the through holes  31  adapted to release inflation gas supplied from the inlet port  19 . A total of opening areas of the through holes  31  is smaller than an opening area of the front/rear opening  30 A/ 30 B. The through holes  31  are located in two positions forming a lateral symmetry in the flow regulating cloth  29 . When the airbag  15  inflates, accordingly, the through holes  31  help stabilize orientation of the front and rear openings  30 A and  30 B, and further stabilize direction of the inflation gas G flowing into the airbag body  16 , by releasing a small portion of the inflation gas G therefrom. As a result, the shoulder restraining portions  26 L and  26 R are supplied with inflation gas properly and generally equally, so that left and right portions of the airbag  15  are developed and inflated equally in further stable manner. Although the flow regulating cloth  29  of the airbag  15  includes two through holes  31  located in symmetric positions with respect to the gas inlet port  19 , the cloth  29  may include only one through hole provided that the hole forms a lateral symmetry. For example, the through hole may be located in one position in the vicinity of transverse center of the flow regulating cloth. It will also be appreciated that the flow regulating cloth includes three or more through holes forming lateral symmetry as a whole, provided that a total of opening areas of the through holes is smaller than an opening area of the front or rear opening, and thereby an outflow of inflation gas from the front or rear opening is not hindered. 
     In the preparatory folding of the airbag  15 , portions defining left and right sides of the outer panel  35 , i.e., the left and right portions  40  and  41  of the first base cloth  38 , are folded on folds CL 1 , CL 2 , CR 1 , and CR 2  extending along front-rear direction in a generally laterally symmetric manner, and the sewn portion  34 , as inner joint, provided in the inner edges  43   a  of the left and right second base cloths  43 L and  43 R is arranged generally along front-rear direction to confront the gas inlet port  19 . Inner sides of the flatly developed left and right shoulder restraining portions  26 L and  26 R up to the projecting tops  26   a , i.e., the upper portions  43   e  of the second base cloths  43 L and  43 R, are located in left and right sides of the sewn portion  34 . That is, in the preparatorily folded airbag  15 , in the developed portion  59 , into which the upper portions  43   e  of the second base cloths  43 L and  43 R are flatly developed while having the sewn portion  43  interposed therebetween, the sewn portion  34  is arranged to confront the inlet port  19 . 
     Accordingly, when the airbag  15  unfolds from preparatorily folded state upon deployment, a portion around the sewn portion  34  confronting the inlet port  19 , i.e., the portion  59   a  of the developed portion  59 , swiftly shifts toward the passenger MP, and the left and right shoulder restraining portions  26 L and  26 R inflate thereafter in a well-balanced manner. That is, since the portion  59   a  and its vicinity swiftly shifts toward the passenger MP, even if the shoulder restraining portions  26 L and  26 R are still not inflated enough, the developed portion  59  being the inner sides of the shoulder restraining portions  26 L and  26 R up to the projecting tops  26   a  moves toward the passenger MP, while securing a generally vertical, wide and flat plane that is integral in left-right direction including the sewn portion  34 . Accordingly, even if a passenger seated proximate to the dashboard advances toward the airbag  15 , the airbag  15  does not unnecessarily apply a partial pressure to the passenger. Especially, since the airbag  15  of the first embodiment is preparatorily folded such that the developed portion  59  is arranged generally in parallel to an opening plane of the gas inlet port  19 , when the airbag  15  is unfolded from the preparatory folding, the whole developed portion  59  advances toward the passenger MP in a generally even manner because of the inflation gas flown in via the inlet port  19 . Therefore, the passenger MP is even more unlikely to receive partial pressure from the airbag  15 . Although the flow regulating cloth  29  is interposed between the developed portion  59  and the inlet port  19 , in the airbag  15 , the inflation gas intensely pushes the developed portion  59  rearward of vehicle together with the flow regulating cloth  29 , in the initial stage of airbag inflation, so that the developed portion  59  is pushed toward the passenger MP. 
     The airbag  15  includes the shoulder restraining portions  26 L and  26 R in left and right parts thereof that project rearward upon airbag inflation. The shoulder restraining portions  26 L and  26 R inflate in a well-balanced manner after the portion  59   a  confronting the inlet port  19  moves toward a passenger, so that a stable deployment is secured from airbag to airbag, with no anxiety of unbalanced inflation. 
     In the airbag  15  of the first embodiment, supposing that the airbag  15  is flatly developed with the projecting tops  26   a  of the shoulder restraining portions  26 L and  26 R lapped in transverse direction, the portion  59   a  confronting the inlet port  19  is positioned in a side of the gas inlet port  19  with respect to the rearmost point  34   a  (the folds CL 1  and CR 1 ) in the sewn portion  34 , by the preparatory folding. However, it is enough that the confronting portion is arranged along the sewn portion  34 , and therefore, position of the confronting portion may be varied according to a type of vehicle on which the airbag  15  is mounted, or according to output of the inflator  8  for supplying the airbag  15  with inflation gas. 
     In the airbag  15 , the opening area S 1  of the communication port  22 , as communication portion which is located proximate to the gas inlet port  19  and communicates the left and right shoulder restraining portions  26 L and  26 R in left-right direction, is predetermined ⅕ or greater (generally ½, in the foregoing embodiment) of the projected area S 2  of a side view of the whole airbag  15  as completely inflated, in a section of the completely inflated airbag  15  taken along front-rear direction generally at the center of the gas inlet port  19 . Accordingly, inflation gas smoothly passes through the communication port  22 , and prevents one of the shoulder restraining portions  26  from inflating more than the other, so that the left and right shoulder restraining portions  26 L and  26 R inflate generally evenly. If the opening area S 1  of the communication port  22  is less than ⅕ of the projected area S 2  of the whole airbag  15 , it is likely that only one of the shoulder restraining portions  26  inflates more than the other upon airbag inflation. 
     In the first embodiment of the present invention, therefore, the airbag  15  protects an approaching passenger properly by inflating the shoulder restraining portions  26 L and  26 R or the two projecting portions constituting the protection portion  25  evenly, so that the second object of the present invention is attained. 
     Moreover, the opening area S 1  of the communication port  22 , which also constitutes the recess  27 , is predetermined ⅕ or greater (generally ½, in the foregoing embodiment) of the projected area S 2  of a side view of the whole airbag  15  as completely inflated. With this great setting of the communication port  22 , a portion of the protection portion  25 , being a bottom of the recess  27 , has a good cushioning property. Even if a head MH of a passenger MP is thrown against the portion of the protection portion  25  in the bottom of the recess  27 , therefore, the head MH is protected by the portion of the protection portion  25  properly. 
     In the airbag  15 , the recess  27  is defined by the sewn portion  34 , which sews up the inner edges  43   a  of the second base cloths  43 L and  43 R constituting the inner wall portions  26   c  of the shoulder restraining portions  26 L and  26 R. Accordingly, the recess  27  provided between the left and right shoulder restraining portions  26 L and  26 R can be deeper or shallower by changing the length of the sewn portion  34  (to paraphrase, length of the inner edges  43   a  of the second base cloths  43 L and  43 R, or a generally inner diameter of the inner edges  43   a ). At the same time, an opening area of the communication port  22  communicating the left and right shoulder restraining portions  26 L and  26 R can be changed by changing the length of the sewn portion  34 , too. That is, in the airbag  15 , a shape of the recess  27  is easily changed without changing an outer contour of the airbag body  16 . 
     Although the outer panel  35  in the airbag  15  is formed by a single piece of cloth, or the first base cloth  38 , having such a shape as the left portion  40  defining the left side wall  16   c  and the right portion  41  defining the right side wall  16   d  are joined together in left-right direction, the shape of the outer panel should not be limited thereby. The outer panel may be constructed of a pair of two base cloths split up into a left portion and a right portion. In addition, although the airbag body  16  is manufactured by sewing work of the base cloths  38 ,  43 L and  43 R, connecting means of the edges of the base cloths should not be limited thereby, but adhesive or the like may be used to connect edges of the base cloths. 
     Furthermore, in the airbag  15 , each of the vent holes  23  in the left/right side wall  16   c / 16   d  is located in a position within an area of the communication port  22  in a side view of the completely inflated airbag body  16 . With this construction, the left and right shoulder restraining portions  26 L and  26 R inflate and develop generally evenly. If the vent hole  23  is located out of the area of the communication port  22  in a side view of the completely inflated airbag body  16 , it is likely that an even inflated condition of the both shoulder restraining portions is not maintained because of decrease of internal pressure in either one of the shoulder restraining portions. 
     A second embodiment of the present invention is now described, by which the first object of the present invention are attainable. As shown in  FIGS. 21 and 22 , an airbag  115  for front passenger&#39;s seat according to the second embodiment is used for an airbag device M 1  for front passenger&#39;s seat, which is located inside the top face  2  of dashboard  1 , as the airbag  15  in the first embodiment. The airbag device M 1  for front passenger&#39;s seat for which the airbag  115  is used has the same construction as the aforedescribed airbag device M 1 , and therefore, its description will be omitted by assigning common reference numerals to common members. 
     The airbag  115  includes an airbag body  116  and a flow regulating cloth  29  disposed inside the airbag body  116 . Since the flow regulating cloth  29  has the same construction as the aforedescribed flow regulating cloth  29  of the airbag  15 , its description will be omitted by assigning common reference numerals to common parts. 
     Referring to  FIGS. 17 to 19 , the airbag body  116  is formed into a generally square conical shape when completely inflated by itself, and its top is in a front end of the airbag body  116 . The airbag body  116  includes an upper side wall  116   a  and a lower side wall  116   b  arranged generally along left-right direction in upper and lower sides, a left side wall  116   c  and a right side wall  116   d  arranged generally along front-rear direction in left and right sides, and a rear wall  116   e  arranged generally along left-right direction to confront a passenger, in such a manner as to connect the upper side wall  116   a  and the lower side wall  116   b . The airbag body  116  includes a protection portion  125  to be arranged in a rear side to face toward a passenger upon airbag inflation, and a vehicle body side portion  117  to be arranged between the dashboard  1  and a wind shield  4  and forward of the protection portion  125  upon airbag inflation, as the aforedescribed airbag body  16 . The vehicle body side portion  117  includes a round gas inlet port  119  and mounting holes  120 , in the vicinity of transverse center of the vehicle body side portion  117  and proximate to a front end of the lower side wall  116   b  in the airbag body  116  as completely inflated, as the aforedescribed airbag body  16 . The airbag body  116  is further provided, in each of the left and right walls  116   c  and  116   d , with a vent hole  123  for exhausting extra inflation gas. 
     The protection portion  125  includes left and right shoulder restraining portions  126 L and  126 R that are disposed side by side in left-right direction with a recess  127  located therebetween, and project rearward in such a manner as to extend vertically. The shoulder restraining portions  126 L and  126 R are adapted to protect shoulders MS of a passenger MP, and its rear plane  126   d  are arranged generally vertically upon airbag inflation. The recess  127  is located in the vicinity of transverse center of the completely inflated airbag body  116 , and is recessed obliquely forward and downward. That is, when the airbag  115  is completely inflated, a rear plane  128  of the recess  127  is directed obliquely upward so as to restrain a head MH of a passenger MP. In the illustrated embodiment, rise of the left and right shoulder restraining portions  126 L and  126 R, and recess of the recess  127  continue forward from the rear side wall  116   e  of the airbag body  116 , in such a manner as to enter within an area of the upper side wall  116   a.    
     More specifically, in a sectional view taken along front-rear direction at transverse center of the airbag  115  as mounted on vehicle and completely inflated, i.e., in a sectional view taken along front-rear direction at the center of the gas inlet port  119 , a tangent line P of the rear plane  128  of the recess  127  is, in its major part except upper and lower ends, slant, having its upper end Pa located forward and lower end Pb located rearward. In the illustrated embodiment, as shown in  FIG. 21 , the tangent line P is tangent to a generally vertical center of the recess rear plane  128 , and a slant angle θ from a horizontal direction is generally 60°. 
     In the recess rear plane  128  of the airbag  115 , a clearance L, as shown in  FIG. 21 , provided between the tangent line P and a tangent line P′ tangent to an upper rear end of the completely inflated airbag body  116  and parallel to the line P is desirably 100 mm or greater (more desirably, 100 mm to 200 mm). If the clearance L is less than 100 mm, a substantial distance between rear planes  126   d  of the shoulder restraining portions  126 L and  126 R and the rear plane  128  of the recess  127 , in a condition that the airbag  115  is completely inflated, is too small. Under this condition, it is hard to obtain a desirable behavior of the airbag  115  that the shoulder restraining portions  126 L and  126 R restrain shoulders MS of a passenger MP firstly, and then the recess rear plane  128  restrains a head MH, so that the head MH may not be restrained softly. In the illustrated embodiment, the clearance L between the tangent lines P and P′ is 150 mm. 
     In addition, in a sectional view of the airbag  115  mounted on vehicle and completely inflated taken along front-rear direction at the center of the gas inlet port  119  in a condition, an upper end part and lower end part of the rear plane  128  of the recess  127  are constructed in such a manner as to branch off from an outline  116   f  of the airbag body  116 . In the illustrated embodiment, an upper end side branching point  128   a  in the recess rear plane  128  is positioned in a lower level than an upper end  125   a  of the protection portion  125 , and in a side of the wind shield  4  with respect to the upper end  125   a . A lower end side branching point  128   b  is positioned in a higher level than a lower end  125   b  of the protection portion  125 , and in a side of a passenger MP with respect to the lower end  125   b.    
     That is, the recess  127  is located in a part of the airbag  115  except a lower end  125   b  vicinity of the protection portion  125 , so that a rear plane  125   c  of the lower end  125   b  vicinity is generally flush with the rear planes  126   d  of the shoulder restraining portions  126 L and  126 R. This lower end  125   b  vicinity portion of the protection portion  125  defines an abdomen restraining portion  129  for restraining an abdomen MB of a passenger MP. When mounted on vehicle and inflated, the airbag  115  is pressed down by the wind shield  4  on the top face. Accordingly, as shown in  FIGS. 19 and 21 , when the airbag inflates by itself, the upper end side branching point  128   a  of the recess rear plane  128  is located forward than when the airbag  115  is mounted on vehicle. 
     As the aforedescribed airbag body  16 , the airbag body  116  is formed by joining edges of predetermined shaped base cloths. The airbag body  116  includes an outer panel  137  constituting the left and right side walls  116   c  and  116   d , and a front part of the lower side wall  116   b , and an inner panel  138  constituting the upper and rear side walls  116   a  and  116   e , and a rear part of the lower side wall  116   b . In the illustrated embodiment, the airbag body  116  is formed of a first base cloth  140  and a pair of second base cloths  145 L and  145 R having the same shapes. The first base cloth  140  constitutes the outer panel  137 , while the second base cloths  145 L and  145 R constitute the inner panel  138 . The first base cloth  140  and the second base cloths  145 L and  145 R of the airbag body  116  have generally the same shapes as the first base cloth  38  and the second base cloths  43 L and  43 R of the aforedescribed airbag body  16 , except shapes of inner edges  145   e  of the second base cloths  145 L and  145 R. 
     Referring to  FIGS. 17 to 20 , the first base cloth  140  has a laterally symmetric shape proximate to a figure of a butterfly spreading its wings. The first base cloth  140  includes a generally rectangular lower part  141  constituting a periphery  118  of the gas inlet port  119  in a vehicle body side portion  117 , and left and right portions  142  and  143 , each of which having a generally triangular plate shape, arranged in such a manner as to extend left and rightwards from the lower part  141 . The lower part  141  makes a front part of the lower side wall  116   b  of the airbag body  116  as completely inflated, which is the vicinity of the gas inlet port  119 . The left and right portions  142  and  143  mainly constitute the left and right side walls  116   c  and  116   d  of the airbag body  116  as completely inflated. Portions in the vicinity of outer edges  142   a  and  143   a  of the left and right portions  142  and  143  constitute left and right ends in the upper, lower and rear side walls  116   a ,  116   b  and  116   e  of the airbag body  116 , or portions proximate to transverse ends of later-described sewn portions  135 L and  135 R, and upper rear portions  142   c  and  143   c  of the outer edge  142   a  and  143   a  vicinity constitute outer wall portions  126   b  located toward transverse ends than projected tops  126   a  of the shoulder restraining portions  126 L and  126 R, respectively, as shown in  FIGS. 17 and 18 . In the illustrated embodiment, the left and right portions  142  and  143  are symmetric to each other with respect to a line running through the center of the inlet port  119 . 
     Referring to  FIGS. 17 to 20 , the second base cloths  145 L and  145 R are arranged in such a manner as to divide an area of the inner panel  138  into two in left-right direction, upon airbag inflation. In the illustrated embodiment, in the airbag body  116  as completely inflated, the second base cloths  145 L and  145 R constitute the upper and rear side walls  116   a ,  116   e  and a rear part of the lower side wall  116   b . Each of the second base cloths  145 L and  145 R has a band shape curved in a generally C-shape with a portion proximate to rear upper part predetermined wider than other part. Rear upper portions  145   b  of the second base cloths  145 L and  145 R constitute inner wall portions  126   c  that are located toward transverse center than the projected tops  126   a  of the shoulder restraining portions  126 L and  126 R. Moreover, front upper portions  145   a  of the second base cloths  145 L and  145 R located forward of the rear upper portions  145   b  constitute the upper side wall  116   a , while rear lower portions  145   d  located below the rear upper portions  145   b  constitute a lower part of the rear side wall  116   e , i.e., a lower end part of the protection portion  125 , or an abdomen restraining portion  129 . Front lower portions  145   c  located forward of the rear lower portions  145   d  constitute a rear part of the lower side wall  116   b.    
     In the illustrated embodiment, an outer edge  145   h  of each of the second base cloths  145 L and  145 R has generally the same shape as the edge  142   a / 143   a  of the left/right portion  142 / 143  in the first base cloth  140  except a root side portion  142   b / 143   b . Moreover, inner edges  145   e  formed in inner circumferences of the second base cloths  145 L and  145 R provide a leading end  127   a  of the recess  127 . 
     The shoulder restraining portions  126 L and  126 R and the recess  127  in the protection portion  125  are formed by sewing up edges of, the left and right portions  142  and  143  of the first base cloth  140 , and the second base cloths  145 L and  145 R. A sewn portion  135 L formed by sewing up the edge  142   a  of the left portion  142  in the first base cloth  140  and the outer edge  145   h  of the second base cloth  145 L, and a sewn portion  135 R, formed by sewing up the edge  143   a  of the right portion  143  and the outer edge  145   h  of the second base cloth  145 R provide, respectively, the projected tops  126   a  of the shoulder restraining portions  126 L and  126 R. A sewn portion  136  formed by sewing up the inner edges  145   e  of the second base cloths  145 L and  145 R provides the leading end  127   a  of the recess  127 . In the airbag  115 , the sewn portion  136  is generally flush with the outline  116   f  of the airbag body  116  as completely inflated, in a portion from the lower end  125   b  vicinity of the protection portion  125 , or the abdomen restraining portion  129 , to the vicinity of the gas inlet port  119 . 
     The airbag body  116  is provided with reinforcing cloths  45  and  46  for reinforcing the inlet port periphery  118 , reinforcing cloths  150 L and  150 R for reinforcing the sewn portions  136 , and a protection cloth  48  for protecting the inlet port periphery  118 . Since the reinforcing cloths  45 ,  46 , and the protection cloth  48  have similar constructions to the reinforcing cloths  45 ,  46 , and the protection cloth  48  of the aforedescribed airbag body  16 , description of those will be omitted by assigning common reference numerals. Each of the reinforcing cloths  150 L and  150 R has a shape curved in a generally C-shape corresponding to the inner edge  145   e  of the second base cloth  145 L/ 145 R, and is adapted to cover an entire area of the inner edge  145   e  of the second base cloth  145 L/ 145 R for reinforcing the sewn portion  136 . 
     The first and second base cloths  140 ,  145 L and  145 R, and the reinforcing cloths  150 L and  150 R are made from flexible woven fabric of polyester, polyamide or the like, as the reinforcing cloths  45 ,  46  and the protection cloth  48 . The woven fabric is not coated by coating agent such as silicone, or the like. 
     The airbag  115  of the second embodiment is manufactured through similar processes as the aforedescribed airbag  15 , i.e., by sewing up the base cloths  140 ,  145 L and  145 R, the reinforcing cloths  45 ,  46 ,  150 L and  150 R, the protection cloth  48 , and a flow regulating cloth material  50 . 
     In the second embodiment, too, the inner panel  138  is formed of a pair of the second base cloths  145 L and  145 R having the generally same shape. Moreover, the outer edge  145   h  of each of the second base cloths  145 L and  145 R has generally the same shape as the edge  142   a / 143   a  of the left/right portion  142 / 143  in the first base cloth  140  constituting the outer panel  137  except the root side portion  142   b / 143   b . Accordingly, sewing positions in the edges of the base cloths easily match one another only by lapping the base cloths  140 ,  145 L and  145 R one on another, which facilitates sewing work of the airbag  115 . 
     The airbag  115  is then folded up and mounted on vehicle as part of the airbag device M 1 , as in the airbag  115 . 
     In the airbag  115  of the second embodiment, when the inflated airbag body  116  is thrown against a passenger MP, left and right shoulders MS of the passenger MP, moving forward, bump against the left and right shoulder restraining portions  126 L and  126 R projecting rearward firstly, so that forward kinetic energy of the passenger MP is reduced. Thereafter, as shown in  FIG. 21 , a head MH of the passenger MP whose shoulders MS are restrained by the shoulder restraining portions  126 L and  126 R enters into the recess  127  provided from upper part to rear part of, and between the shoulder restraining portions  126 L and  126 R, and then is restrained and suppressed from moving forward. When the head MH of the passenger MP bumps against the recess rear plane  128 , since the rear plane  128  has such construction as the tangent line P of the rear plane  128  is slant, having its upper end located forward and lower end located rearward, the airbag  115  softly receives the head MH of the passenger MP, while keeping the head MH in slant condition, with the rear plane  128  of the recess  127  which is generally smooth and generally parallel to an upper body of the passenger MP leaning forward. Accordingly, in the airbag  115  for front passenger&#39;s seat in the second embodiment, the head MH of the passenger MP is received softly while reaction force from the airbag  115  is suppressed, after the kinetic energy is reduced by the shoulder restraining portions  126 L and  126 R. 
     Accordingly, in the second embodiment, too, the airbag  115  for front passenger&#39;s seat is capable of, when completely inflated and thrown against the head MH of the passenger MP, protecting the head MH properly while suppressing reaction force, thereby attaining the first object of the present invention. 
     In the airbag  115  of the second embodiment, moreover, the rear plane  128  of the recess  127  is, in its major part except upper and lower ends, a slant plane having its upper end located forward and lower end located rearward. Accordingly, even if a level of a head MH of a seated passenger MP is changed, the airbag  115  receives the head MH with a slant portion of the recess rear plane  128 . As shown in  FIG. 22 , more specifically, even when a passenger MP′ of small build is seated in a front passenger&#39;s seat, the airbag  115  receives the head MH′ of the passenger MP′, which should be located in a lower level compared with a head MH of a passenger MP of large build, with the slant rear plane  128  of the recess  127 , in the same manner as receives the head MH of the passenger MP. Accordingly, in the second embodiment, too, the airbag  115  protects the heads MH and MH′ of the passenger MP and MP′ softly, regardless of physique of passenger. 
     In the airbag  115 , the lower end side branching point  128   b  of the recess rear plane  128  from the airbag outline  116   f  is positioned in a higher level than the lower end  125   b  of the protection portion  125 , and in a side of a passenger MP with respect to the lower end  125   b , in a sectional view of the airbag  115  mounted on vehicle and completely inflated taken along front-rear direction at the center of the gas inlet port  119 . Accordingly, a lower end portion or the abdomen restraining portion  129  in the inflated airbag  115  deployed between the dashboard  1  and a passenger&#39;s abdomen MB inflates in a thick manner, so that the abdomen MB is protected by the abdomen restraining portion  129  in a stable manner. 
     Furthermore, the upper end side branching point  128   a  of the recess rear plane  128  from the airbag outline  116   f  is positioned in a lower level than the upper end  125   a  of the protection portion  125 , and in a side of the wind shield  4  with respect to the upper end  125   a , in a sectional view of the airbag  115  mounted on vehicle and completely inflated taken along front-rear direction at the center of the gas inlet port  119 . That is, when the airbag  115  is completely inflated, the recess  127  is so formed that the rear plane  128  in an upper end part thereof is recessed deeply. In other words, in the airbag  115 , a distance between the rear planes  126   d  of the shoulder restraining portions  126 L and  126 R and the recess rear plane  128  becomes greater as it goes from lower end to upper end. With this construction, as shown in  FIG. 22 , when a passenger MP′ of small build is seated, a head MH′ of the passenger MP′ is to be protected by a portion of the rear plane  128  where the distance between the rear planes  126   d  of the shoulder restraining portions and the recess rear plane  128  is small. However, since a moving distance of the head MH′ from shoulders MS′ upon collision is small in case of the small build passenger MP′, even if the distance between the rear planes  126   d  of the shoulder restraining portions and the recess rear plane  128  is small, it is prevented that the head MH′ bumps against the airbag  115  prior to the shoulders MS′. That is, the head MH′ is restrained by the recess rear plane  128  after the shoulders MS′ are restrained by the shoulder restraining portions  126 L and  126 R, so that impact to a neck is reduced, and the head MH′ is softly protected. On the contrary, when a large build passenger MP is seated, as shown in  FIG. 21 , a moving distance of his head MH from shoulders MS upon collision is greater in comparison with the small build passenger MP′. However, with the airbag  115 , the head MH of the large build passenger MP is protected by an upward portion of the rear plane  128  than the portion to restrain the head MH′ of the small build passenger MP′, where the distance between the rear planes  126   d  of the shoulder restraining portions and the recess rear plane  128  is greater. Accordingly, it is prevented that the head MH bumps against the airbag  115  prior to the shoulders MS. That is, the head MH is restrained by the recess rear plane  128  after the shoulders MS are restrained by the shoulder restraining portions  126 L and  126 R, as in a case of the small build passenger MP′, so that impact to a neck is reduced, and the head MH is softly protected. Consequently, the airbag  115  is capable of protecting the heads MH and MH′ in accordance with physique of passenger. 
     As shown in  FIG. 21 , the clearance L between the tangent line P tangent to the recess rear plane  128  at generally vertical center of the recess rear plane  128  and the tangent line P′ tangent to an upper rear end of the completely inflated airbag body  116  and parallel to the line P is predetermined 100 mm or greater. This construction secures enough distance between the rear planes  126   d  of the shoulder restraining portions  126 L and  126 R and the recess rear plane  128  in the completely inflated airbag body  116 . Accordingly, the head MH is restrained by the recess rear plane  128  after the shoulders MS are restrained by the shoulder restraining portions  126 L and  126 R, so that the head MH of the passenger MP is softly protected by the recess rear plane  128 . 
     In the second embodiment, too, the sewn portion  136  sewing up the inner edges  145   a  of the second base cloths  145 L and  145 R, which constitute the inner panel  138 , is arranged in a generally transverse center of the inflated airbag body  116  generally all over the circumference of the airbag body  116  in generally vertical direction. Accordingly, the whole base cloths of the airbag body  116  is regulated in developing direction by the sewn portion  136  when developed and inflated, so that the rear wall  116   e  to be deployed toward passenger is prevented from projecting toward passenger upon airbag inflation, and a contour of the completely inflated airbag body  116  is regulated. As a result, the airbag body  116  no longer needs a tether or the like which would pull the rear wall  116   e  forward i.e., in a direction opposite to passenger and regulate the contour of the airbag body as completely inflated, so that number of parts of the airbag  115  is reduced. 
     Moreover, the airbag  115  of the second embodiment also includes the flow regulating cloth  29  having a generally cylindrical shape, and located inside the airbag body  116  to cover the gas inlet port  119  from upper side. Since the flow regulating cloth  29  is so opened at front and rear ends so as to redirect inflation gas G flown in via the inlet port  119  forward and rearward, the inflation gas G flown in via the inlet port  119  is supplied into the airbag body  116  from front and rear openings  30 A and  30 B of the flow regulating cloth  29  along front-rear direction, upon airbag inflation. That is, a lower part of the airbag body  116 , especially the abdomen restraining portion  129  located in a rear lower part of the airbag body  116 , is developed along the dashboard  1 , so that the airbag  115  is prevented from unnecessarily protruding toward a passenger MP. 
     Furthermore, in the airbag  115 , too, the recess  127  provided between the shoulder restraining portions  126 L and  126 R is defined by the sewn portion  136 , which sews up the inner edges  145   a  of the second base cloths  145 L and  145 R constituting the inner wall portions  126   c  of the shoulder restraining portions  126 L and  126 R. Accordingly, a shape of the recess  127 , or a slant angle or the like of the recess rear plane  128 , can be changed by changing a shape of the sewn portion  136 , or a shape of the inner edges  145   a  of the second base cloths  145 L and  145 R. 
     Although the outer panel  137  of the airbag  115  is formed by a single piece of cloth, or the first base cloth  140 , having such a shape as the left portion  142  defining the left side wall  116   c  and the right portion  143  defining the right side wall  116   d  are joined together in left-right direction, in the second embodiment, too, the outer panel may be constructed of a pair of two base cloths split up into a left portion and a right portion. 
     A third embodiment of the present invention is now described, by which the first object of the present invention are attainable. As shown in  FIG. 23 , an airbag  215  for front passenger&#39;s seat according to the third embodiment is used for an airbag device M 2  for front passenger&#39;s seat, which is a top-mount type attached to an interior of top face  2  of a dashboard  1 . 
     Referring to  FIGS. 23 to 25 , the airbag device M 2  for front passenger&#39;s seat includes a folded airbag  215 , an inflator  8  for supplying inflation gas to the airbag  215 , a case  6 A for housing and holding the airbag  215  and the inflator  8 , a retainer  11  for attaching the airbag  215  to the case  6 A, an airbag cover  10  covering the folded airbag  215 , and a release adjuster  245  adapted to adjust lengths of tethers  242  and  243  disposed within the airbag  215 . The airbag device M 2  has a similar construction to the aforedescribed airbag device M 1 , except the airbag  215  and release adjuster  245 , and therefore, descriptions of the common members will be omitted by assigning common reference numerals. A bottom wall  6   a  of the case  6 A is provided with through holes  6   c  for inserting the tethers  242  and  243  of the airbag  215  therethrough, other than apertures for inserting a body  8   a  of the inflator  8  and bolts  11   a  therethrough. 
     Referring to  FIGS. 26 to 28 , the airbag  215  is formed into a generally square conical shape when completely inflated by itself. A front end of the airbag  215  defines a top of the square cone, and a rear side of bottom side constitutes a protection portion  227 . The airbag  215  is folded and housed in an interior side of top face  2  of the dashboard  1 , when not in service. When fed with inflation gas, the airbag  215  protrudes upward and rearward in such a manner as to occupy a space between the top face  2  of dashboard  1  and a wind shield  4 , thereby protecting a passenger by a rear side thereof or the protection portion  227 . 
     The protection portion  227  as inflated includes left and right shoulder restraining portions  228 L and  228 R for protecting the vicinities of passenger&#39;s left and right shoulders. Provided vertically between the shoulder restraining portions  228 L and  228 R is a center restraining portion  229 , which is recessed forward, for protecting a portion of a passenger between shoulders including at least a head. 
     The airbag  215  includes a generally square conical bag shaped airbag body  216 , and a plurality of (two, in the third embodiment) tethers  242  and  243  disposed inside the airbag body  216 . A rear side of the airbag body  216  serves as the protection portion  227 , and apart located forward of the protection portion  227  serves as a vehicle body side portion  217  to contact the top face  2  of dashboard  1  and the wind shield  4 . As in the aforedescribed airbag  15  and airbag  115 , the vehicle body side portion  217  includes a gas inlet port  220  and mounting holes  221 , in the vicinity of transverse center and proximate to a front end of a lower side thereof. The vehicle body side portion  217  is also provided with through holes  222  for inserting the tethers  242  and  243  therethrough, in the vicinity of transverse center and proximate to the front end of the lower side thereof. 
     As shown in  FIGS. 26 to 29 , the airbag body  216  is manufactured by joining outer edges of two kinds of panel portions, i.e., an outer panel  232  and an inner panel  233 . The outer panel  232  defines left and right walls  215   c  and  215   d  of the generally square conical shape which the airbag  215  is formed into when completely inflated, whereas the inner panel  233  defines an area ranging from an upper wall  215   a  to a lower wall  215   b , via a rear wall  215   e , of the generally square conical shape, between the left and right walls  215   c  and  215   d.    
     Referring to  FIG. 29 , the airbag body  216  is formed of a first base cloth  235  and a pair of second base cloths  240 L and  240 R as inner panel base cloth. The first base cloth  235  constitutes the outer panel  232 , while the second base cloths  240 L and  240 R, having the same shapes, constitute the inner panel  233 . The first base cloth  235  has a laterally symmetric shape proximate to a figure of a butterfly spreading its wings. The first base cloth  235  includes a generally rectangular lower part  236  constituting a periphery  219  of the gas inlet port  220  in a vehicle body side portion  217 , and left and right portions  237  and  238 , each of which having a generally triangular plate shape, arranged in such a manner as to extend left and rightwards from the lower part  236 . The lower part  236  makes a front part of the lower side wall  215   b  of the airbag  215  as completely inflated, which is the vicinity of the gas inlet port  220 . The left and right portions  237  and  238  mainly constitute the left and right side walls  215   c  and  215   d  of the airbag  215  as completely inflated. Portions in the vicinity of outer edges  237   a  and  238   a  of the left and right portions  237  and  238  constitute outer wall portions  228   b  located toward transverse ends than projected tops  228   a  of the shoulder restraining portions  228 L and  228 R, respectively. The left and right portions  237  and  238  are symmetric to each other with respect to a line running through the center of the inlet port  220 . 
     The second base cloths  240 L and  240 R are arranged in such a manner as to divide an area of the inner panel  233  into two in left-right direction, upon airbag inflation. Each of the second base cloths  240 L and  240 R has a band shape or flat shape curved in a generally C-shape. In the airbag  215  as completely inflated, the second base cloths  240 L and  240 R constitute the upper side wall  215   a , the rear side wall  215   e , and a rear part of the lower side wall  215   b . The second base cloths  240 L and  240 R also constitute inner wall portions  228   c  that are located toward transverse center than the projected tops  228   a  of the shoulder restraining portions  228 L and  228 R. 
     An outer edge  240   d  of each of the second base cloths  240 L and  240 R has generally the same shape as an outer edge (edge portion)  237   a / 238   a  of the left/right portion  237 / 238  in the first base cloth  235  except a root side portion  237   b / 238   b . Inner edges  240   a  formed in inner circumferences of the second base cloths  240 L and  240 R provide a leading end or inner edge  229   a  of the center restraining portion  229 , which is most recessed, and also constitute an inner edge of a communication port  223  that communicates the left and right shoulder restraining portions  228 L and  228 R. 
     The first and second base cloths  235 ,  240 L and  240 R are made from flexible woven fabric of polyester, polyamide or the like. The woven fabric is not coated by coating agent such as silicone, or the like. 
     The shoulder restraining portions  228 L and  228 R and the center restraining portion  229  in the protection portion  227  are formed by sewing up edges of, the left and right portions  237  and  238  of the first base cloth  235 , and the second base cloths  240 L and  240 R. More specifically, a sewn portion  230 L formed by sewing up the edge  237   a  of the left portion  237  in the first base cloth  235  and the outer edge  240   d  of the second base cloth  240 L, and a sewn portion  230 R formed by sewing up the edge  238   a  of the right portion  238  and the outer edge  240   d  of the second base cloth  240 R provide, respectively, the projected tops  228   a  of the shoulder restraining portions  228 L and  228 R. The vicinity of a sewn portion  231  formed by sewing up the inner edges  240   a  of the second base cloths  240 L and  240 R provides the inner edge  229   a  of the center restraining portion  229 . 
     In the airbag body  216 , the shoulder restraining portions  228 L and  228 R are communicated with each other in left-right direction with a communication port  223  defined by the inner edge  229   a  of the center restraining portion  229 . The communication port  223  is defined by the sewn portion  231  sewing up the inner edges  240   a  of the second base cloths  240 L and  240 R, or the inner edge  229   a  of the center restraining portion  229 , and the lower part  236  of the first base cloth  235 . The communication port  223  ranges from lower side of the protection portion  227  to lower side of the vehicle body side portion  217  in the completely inflated airbag body  216 . When the airbag body  216  is completely inflated, an opening plane of the communication port  223  is arranged along front-rear direction in generally transverse center of the airbag body  216 . 
     The airbag body  216  is further provided, in each of the left and right walls  215   c  and  215   d , with a vent hole  224  for exhausting extra inflation gas. 
     Each of the tethers  242  and  243  is sewn into the sewn portion  231  at an upper end  242   a / 243   a  thereof, when the inner edges  240   a  of the second base cloths  240 L and  240 R are sewn up, so that the tethers  242  and  243  are disposed one below another in a vertical inner edge of the center restraining portion  229 , in the completely inflated airbag body  216 . Lower ends  242   b  and  243   b  of the tethers  242  and  243  extend obliquely downward and forward within the airbag body  216 . In the illustrated embodiment, each of the tethers  242  and  243  is made of metal or fabric string member in a loop. The lower ends  242   b  and  243   b  protrude out of the two through holes  222  located front and rear of the gas inlet port  220  in the periphery  219  of the inlet port  220 , and protrude downward of the airbag body  216 . The lower ends  242   b  and  243   b  are further extracted from the through holes  6   c  of the case  6 A, and connected to the release adjuster  245  when the airbag device M 2  is mounted on vehicle. The upper ends  242   a  and  243   a  of the tethers  242  and  243  are joined to the vicinity of upper end, and the vicinity of vertical center, respectively, of the center restraining portion  229  in the rear plane  215   e.    
     Referring to  FIGS. 23 to 25 , the release adjuster  245  includes cases  246 , and one each first, second and third stopper pin  247 ,  248  and  249  per each case. Each of the cases  246  is fixed to the case  6 A in such a manner as to extend from the through hole  6   c  of the case  6 A and confront each other. Each of the pins  247 ,  248  and  249  is retained by walls  246   a  and  246   b  of each of the cases  246 . The first stopper pin  247  located proximate to the case bottom wall  6   a  is fixed to the walls  246   a  and  246   b  at both ends thereof, whereas the second and third stopper pins  248  and  249 , which are remote from the case bottom wall  6   a  in this order, are movable cores of electromagnetic solenoids  251  and  252  fixed to the wall  246   a . The lower ends  242   b  and  243   b  of the loop-shaped tethers  242  and  243  are wound on the third pins  249  while having all the pins  247 ,  248  and  249  put through the loop. 
     Each of the electromagnetic solenoids  251  and  252  is controlled by a control device  254  of the airbag device M 2 . The control device  254  receives electric signals from an unillustrated sensor for detecting frontal collision of vehicle, and a weight sensor  255  mounted on front passenger&#39;s seat to detect weight of a passenger seated therein. 
     Upon frontal collision in a condition that the sensor  255  is detecting that a passenger seated in front passenger&#39;s seat is of large build, the control device  254  outputs activating signals to the electromagnetic solenoids  251  and  252  as well as to the inflator  8 , so that the solenoids  251  and  252  are activated to pull the pins  248  and  249  out of the walls  246   b  and retract them toward the walls  246   a . At this time, the tethers  242  and  243  are retained only by the first stopper pins  247  at the lower ends  242   b  and  243   b , and accordingly, length of the upper ends  242   a  and  243   a  parts of the tethers  242  and  243  released into the completely inflated airbag body  216  is most elongated. That is, the center restraining portion  229  of the completely inflated airbag  215  is located in a rearmost position D 1 , as indicated by solid lines in  FIGS. 27 ,  30  and  31 . 
     Upon collision in a condition that the sensor  255  is detecting that a passenger seated in front passenger&#39;s seat is of small build, the control device  254  outputs an activating signal only to the inflator  8 , but not to the electromagnetic solenoids  251  and  252 . Then the pins  248  and  249  are kept retained across the walls  246   a  and  246   b . At this time, the tethers  242  and  243  are retained by the third stopper pins  249  at the lower ends  242   b  and  243   b , and accordingly, length of the upper ends  242   a  and  243   a  parts of the tethers  242  and  243  released into the completely inflated airbag body  216  is most shortened. That is, the center restraining portion  229  of the completely inflated airbag  215  is located in a foremost position D 3 , as indicated by double-dotted lines in  FIGS. 27 ,  32  and  33 . 
     Moreover, upon collision in a condition that the sensor  255  is detecting that a passenger seated in front passenger&#39;s seat is of average build, the control device  254  outputs activating signals only to the electromagnetic solenoids  252  as well as to the inflator  8 , but not to the solenoids  251 . Then the solenoids  252  are activated to pull only the pins  249  out of the walls  246   b  and retract them toward the walls  246   a . At this time, the tethers  242  and  243  are retained by the second stopper pins  248  at the lower ends  242   b  and  243   b , and accordingly, length of upper ends  242   a  and  243   a  parts of the tethers  242  and  243  released into the completely inflated airbag body  216  is medium. That is, the center restraining portion  229  of the completely inflated airbag  215  is located in a middle position D 2  between the rearmost position D 1  and the foremost position D 3 , as indicated by single-dotted lines in  FIG. 27 , or solid lines in  FIGS. 32 and 33 . 
     When assembling the release adjuster  245 , the walls  246   a  are secured to a lower side of the bottom wall  6   a  of the case  6 A in a condition that the electromagnetic solenoids  251  and  252  are fixed to the walls  246   a  in advance, whereas the first stopper pins  247  are fixed to the walls  246   b . Assembling of the adjuster  245  is conducted by firstly inserting the first stopper pins  247  through the walls  246   a  in a condition that the lower ends  242   b  and  243   b  parts of the tethers  242  and  243  are wound around the second stopper pins  248  and the third stopper pins  249 , attaching the walls  246   b  to the walls  246   a  while inserting the second and third pins  248  and  249  through the walls  246   b , and then by attaching C-rings  253  for holding the stopper pins  247 . Thus the release adjuster  245  is assembled with the case  6 A, and the lower ends  242   b  and  243   b  of the tethers  242  and  243  are joined to the adjuster  245 . 
     To manufacture the airbag  215  according to the third embodiment, the second base cloths  240 L and  240 R are lapped with each other with the upper ends  242   a  and  243   a  of the tethers  242  and  243  put therebetween, and the inner edges  240   a  of the second base cloths  240 L and  240 R are sewn up together with the upper ends  242   a  and  243   a , firstly. Subsequently, front edges  240   b  of the second base cloths  240 L and  240 R are sewn to a front edge  236   a  of the lower part  236  in the first base cloth  235 , and rear edges  240   c  of the second base cloths  240 L and  240 R are also sewn to a rear edge  236   b  of the lower part  236  in the first base cloth  235 . Then front and rear left edges  236   c  of the lower part  236  are sewn to the root side edges  237   b  of the edge  237   a  in the left portion  237 , while right edges  236   d  are sewn to the root side edges  238   b  of the edge  238   a  in the right portion  238 . Thereafter, the edge  237   a  of the left portion  237  and the outer edge  240   d  of the second base cloth  240 L are sewn up, while the edge  238   a  of the right portion  238  and the outer edge  240   d  of the second base cloth  240 R are sewn up. If then the airbag  215  is reversed inside out utilizing the gas inlet port  220  so that stitch allowances may not appear on surface, and the lower ends  242   b  and  243   b  parts of the tethers  242  and  243  are extracted from the through holes  222 , the airbag  215  is complete. 
     In the airbag  215  according to the third embodiment, too, the second base cloths  240 L and  240 R are formed in a pair each of which having the generally same shape, and the outer edge portion  240   d  of each of the second base cloths  240 L and  240 R has generally the same shape as the edge  237   a / 238   a  of the left/right portion  237 / 238  in the first base cloth  235  constituting the outer panel  232  except the root side portion  237   b / 238   b . Accordingly, sewing positions in the edges of the base cloths easily match one another only by lapping the base cloths  235 ,  240 L and  240 R one on another, which facilitates sewing work of the airbag  215 . 
     After manufacturing the airbag  215 , the airbag  215  is folded up with the retainer  11  disposed inside such that bolts  11   a  of the retainer  11  are protruded from the mounting holes  221 . Then the folded-up airbag  215  is wrapped by a breakable wrapping sheet  14  (refer to  FIGS. 23 and 24 ) to keep the folded-up configuration. At this time, the lower ends  242   b  and  243   b  parts of the tethers  242  and  243  are taken out of the wrapping sheet  14 . Then the folded-up airbag  215  is placed on the bottom wall  6   a  of the case  6 A by putting the bolts  11   a  of the retainer  11  through the bottom wall  6   a , and the lower ends  242   b  and  243   b  parts of the tethers  242  and  243  are protruded downward from the through holes  6   c  of the case  6 A. Subsequently, the body  8   a  of the inflator  8  is set in the case  6 A from lower side of the bottom wall  6   a , while the bolts  11   a  protruded downward from the bottom wall  6   a  are inserted through the flange  8   a  of the inflator  8 . Thereafter, by fastening the bolts  11   a  protruded from the flange  8   c  of the inflator  8  into nuts  12 , the folded-up airbag  215  and the inflator  8  are attached to the bottom wall  6   a  of the case  6 A. 
     As aforedescribed, the release adjuster  245  is assembled so that the lower ends  242   b  and  243   b  of the tethers  242  and  243  are connected to the release adjuster  245 . 
     Then the airbag device M 2  for front passenger&#39;s seat is mounted on vehicle if a side wall  6   b  of the case  6 A is retained by a joint wall  10   c  of an airbag cover  10  in the dashboard  1  having been mounted on vehicle, unillustrated brackets of the case  6 A are fixed to predetermined positions of vehicle body, and unillustrated wires leading from the control device  254  are connected to the inflator  8  and the electromagnetic solenoids  251  and  252 . 
     When mounted on vehicle and deployed, the airbag  215  for front passenger&#39;s seat according to the third embodiment of the present invention completes inflation in a condition that the center restraining portion  229  located between the shoulder restraining portions  228 L and  228 R is recessed forward in the protection portion  227 . Accordingly, when the inflated airbag  215  is thrown against a passenger Mp, left and right shoulders Ms of the passenger Mp bump against the left and right shoulder restraining portions  228 L and  228 R projecting rearward firstly, so that forward kinetic energy of the passenger Mp is reduced. Thereafter, a head Mh of the passenger Mp enters into the center restraining portion  229  provided between the shoulder restraining portions  228 L and  228 R, and then is restrained and suppressed from moving forward. Accordingly, the head Mh of the passenger Mp is received softly while reaction force from the airbag  215  is suppressed, after kinetic energy is reduced by the shoulder restraining portions  228 L and  228 R. 
     According to the third embodiment, in a condition that the airbag  215  is mounted on vehicle and completely inflated, a disposition of the center restraining portion  229  in front-rear direction is adjustable into positions D 1 , D 2  and D 3 , as shown in  FIG. 27 . For example, if a passenger Mp seated in front passenger&#39;s seat is of large build, the center restraining portion  229  is disposed in the rearmost position D 1  so as to be less recessed from the shoulder restraining portions  228 L and  228 R, as indicated by solid lines in  FIGS. 27 ,  30  and  31 . This means that the airbag  215  comes to have more volume when inflated, so that it may take the airbag  215  longer time to complete inflation. However, under a circumstance that the passenger Mp of large build is seated farther rearward from the airbag  215 , the shoulder restraining portions  228 L and  228 R of the completely inflated airbag  215  restrain left and right shoulders Ms properly, and then the center restraining portion  229  receives a head Mh of the passenger Mp softly. 
     In this case, although the center restraining portion  229  is more proximate to the head Mh of the passenger Mp, when disposed in the rearmost position D 1 , than when in the forward positions D 2  or D 3 , a forward kinetic energy of the large build passenger Mp is absorbed by the shoulder restraining portions  228 L and  228 R smoothly, since the shoulder restraining portions  228 L and  228 R are inflated thick enough in left-right direction, so that the head Mh of the passenger Mp is received softly, too, by the center restraining portion  229 . 
     If a passenger Mp seated in front passenger&#39;s seat is of small build, the passenger Mp is seated more forward. The center restraining portion  229  is disposed in the foremost position D 3  so as to be more recessed from the shoulder restraining portions  228 L and  228 R, as indicated by double-dotted lines in  FIGS. 27 ,  32  and  33 . This means that the airbag  215  comes to have less volume when inflated, and it takes the airbag  215  a shorter time to complete inflation. With this construction, the left and right shoulder restraining portions  228 L and  228 R restrain shoulders Ms of the small build passenger Mp moving forward firstly, and then the center restraining portion  229  receives a head Mh of the small build passenger Mp softly by the rear plane  229   b.    
     In this case, since the center restraining portion  229  is disposed more forward, or deeply recessed than when disposed in the position D 1 , the airbag  215  properly restrains the head Mh of the passenger Mp by the rear plane  229   b  of the center restraining portion  229  disposed in the front position D 3 , after restraining the shoulders Ms by the shoulder restraining portions  228 L and  228 R, even if the passenger Mp is seated proximate to the airbag  215 . Accordingly, the head Mh of the passenger Mp is received softly. 
     In this case, even if a passenger Mp seated proximate to the airbag  215  is of large build, the shoulder restraining portions  228 L and  228 R restrain the shoulders Ms of the passenger Mp and absorb enough kinetic energy of the passenger Mp because of long absorbing stroke, before protecting a head Mh by the rear plane  229   b  of the center restraining portion  229  deeply recessed forward. Accordingly, the head Mh of the large build passenger Mp is received softly, too, by the rear plane  229   b  of the center restraining portion  229 . 
     Furthermore, if a passenger Mp is average build, the center restraining portion  229  is located in the middle position D 2  upon airbag inflation, as indicated by single-dotted lines in  FIG. 27  and by solid lines in  FIGS. 32 and 33 . A passenger&#39;s head Mh is protected softly by the rear plane  229   b  of the center restraining portion  229  in a condition that his kinetic energy is reduced by restraint of shoulders Ms by the shoulder restraining portions  228 L and  228 R. 
     According to the third embodiment, therefore, the airbag  215  is capable of protecting a head Mh of passenger Mp in accordance with physique and seated position of the passenger, when the head Mh is thrown against the completely inflated airbag  215 . 
     Since the airbag  215  is capable of receiving a head Mh of large build passenger Mp softly even if the large build passenger Mp is seated proximate to the airbag  215 , the sensor  255 , which is to monitor passenger&#39; weight, can be replaced by a distance sensor for monitoring passenger&#39;s seated position in front-rear direction, such as a distance sensor for monitoring a clearance between the dashboard  1  and a passenger, or a distance sensor for monitoring seat position in front-rear direction, so that the control device  254  controls the adjuster  245  such that, if it is monitored that a passenger is seated in a forward position, the rear plane  229   b  of the center restraining portion  229  be deployed in the position D 3 , and if it is monitored that a passenger is seated in a rearward position, the rear plane  229   b  be deployed in the position D 1 , and moreover, if a passenger is seated in a middle position in front-rear direction, the rear plane  229   b  be deployed in the position D 2 . 
     In the airbag  215 , disposition of the center restraining portion  229  is adjusted by the two tethers  242  and  243  that are disposed one below another in the vertical inner edge  229   a  of the center restraining portion  229 , and extend forward within the airbag  215 . Accordingly, by changing lengths of the tethers  242  and  243 , not only a position in front-rear direction, but also a slant angle of the center restraining portion  229  from horizontal orientation can be adjusted. More specifically, if a length of the front tether  242  released from the adjuster  245  is elongated whereas a length of the rear tether  243  released from the adjuster  245  is shortened, the rear plane  229   b  of the center restraining portion  229  has more backward descending slant angle from horizontal orientation, with the front end located more upward and the rearward more downward, as indicated by single-dotted lines in  FIG. 31 . On the contrary, if a length of the tether  242  released from the adjuster  245  is shortened whereas a length of the tether  243  released from the adjuster  245  is elongated, the rear plane  229   b  of the center restraining portion  229  has less backward descending slant angle from horizontal orientation, as indicated by double-dotted lines in  FIG. 31 . 
     In the third embodiment, too, the joint  231  is disposed in generally entire circumference of the airbag  215 , along front-rear direction and in generally transverse center of the airbag  215  as completely inflated. A length of each of the inner edges  240   a  of inner panel base cloths  240 , which constitute the joint  231 , is predetermined shorter than that of each of the outer edges  240   d  of inner panel base cloths  240 . That is, the joint  231  does not project outward, or located inside of an outline of the airbag  215  as viewed from side when completely inflated. With this construction, the protection portion  227  having the shoulder restraining portions  228 L and  228 R in a rear side and the recessed center restraining portion  229  between the shoulder restraining portions  228 L and  228 R is easily made out of a base cloth  235  for forming the outer panel  232  and two base cloths  240  for forming the inner panel  233 . 
     In addition, in the airbag  215 , the tethers  242  and  243  are easily attached to the airbag  215  when the inner edges  240   a  of the inner panel base cloths  240  are joined to each other. 
     Disposition of the center restraining portion  229  may be adjusted also by adjusting length of a string member  257  which is disposed generally all along the inner edge  229   a  of the center restraining portion  229 , as in an airbag  215 A shown in  FIGS. 37 and 38 . The airbag  215 A is a modification of the third embodiment. 
     Referring to  FIGS. 34 to 36 , the string member  257  is made of flexible metal or fabric. The airbag  215 A is constructed such that the string member  257  goes through and along a joint of inner edges  240   a  of inner panel base cloths  240 . A rear end  257   b  of the string member  257  is fixed to a rear edge  240   c  of the inner edge  240   a , whereas a front end  257   a  of the string member  257  is pulled out of a front edge  240   b  of the inner edge  240   a  into inner space of the airbag body  216 , and taken out of the airbag body  216  via a through hole  222 , and then extended up to a third stopper pin  249  as part of the release adjuster  245  having the same construction as that in the aforedescribed airbag  215 , and wound therearound. A terminal of this front end  257   a  is fixed to a wall  246   a  of a case  246  with a fixing member  258 , and thus the front end  257   a  of the string member  257  is joined with the adjuster  245 . 
     The airbag  215 A differs from the aforedescribed airbag  215  in that the string member  257 , instead of the tethers  242  and  243 , is disposed along the inner edges  240   a  of the inner panel base cloths  240 , or the inner edge  229   a  of the center restraining portion  229 , in such a manner as to go back and forth along the inner edge  240   a  or  229   a , while having the rear end  257   b  fixed to the airbag body  216 , and having the front end  257   a  wound around pins  247 ,  248  and  249 , and then the terminal of the front end  257   a  is fixed to the case  246 , and in that the airbag  215 A has only one through hole  222  in front part thereof. However, other constructions of the airbag  215 A are similar to those of the airbag  215 , and therefore, descriptions of common members or the like will be omitted by assigning those members common reference numerals. In addition, the airbag  215 A is folded up and mounted on vehicle together with the case  6 A, an inflator  8  and an airbag cover  10 , in a similar manner to the aforedescribed airbag  215 . 
     Moreover, the release adjuster  245 , to which the front end  257   a  of the string member  257  is joined, has a similar construction to the aforedescribed adjuster  245 , as shown in  FIGS. 34 to 36 . The case  6 A has only one through hole  6   c  in a front part of a bottom wall  6   a.    
     In the airbag  215 A, upon frontal collision in a condition that a sensor  255  is detecting that a passenger Mp seated in front passenger&#39;s seat is of large build, a control device  254  outputs activating signals to electromagnetic solenoids  251  and  252  as well as to the inflator  8 , so that the solenoids  251  and  252  are activated to pull the pins  248  and  249  out of the walls  246   b  and retract them toward the walls  246   a . At this time, the string member  257  is retained only by the first stopper pin  247  at the front end  257   a , and accordingly, length of the string member  257  released into the completely inflated airbag body  216  is most elongated. That is, a substantial length of a joint  231  of the inner edges  240   a  of the base cloths  240  is elongated, in other words, an inner edge of a communication port  223  is expanded, so that the inner edge  229   a  of the center restraining portion  229  of the completely inflated airbag  215 A is located in a rearmost position D 1 , as indicated by solid lines in  FIGS. 37 to 40 . 
     As a result, the center restraining portion  229  is disposed in the rearmost position D 1  so as to be less recessed from left and right shoulder restraining portions  228 L and  228 R. That is, the airbag  215 A comes to have more volume when inflated, so that it may take the airbag  215 A longer time to complete inflation. However, under a circumstance that the large build passenger Mp is seated farther rearward from the airbag  215 A, the shoulder restraining portions  228 L and  228 R of the completely inflated airbag  215 A restrain left and right shoulders Ms properly, and then the center restraining portion  229  receives a head Mh of the passenger Mp softly. 
     Upon collision in a condition that the sensor  255  is detecting that a passenger Mp seated in front passenger&#39;s seat is of small build, the control device  254  outputs an activating signal only to the inflator  8 , but not to the electromagnetic solenoids  251  and  252 . Then the pins  248  and  249  are kept retained across the walls  246   a  and  246   b . At this time, the front end  257   a  of the string member  257  is retained by the third stopper pin  249 , and accordingly, length of the string member  257  released into the completely inflated airbag body  216  is most shortened. That is, the substantial length of the joint  231  of the inner edges  240   a  of the base cloths  240 , or the length of the inner edge of the communication port  223  is shortened, so that the inner edge  229   a  of the center restraining portion  229  is located in a foremost position D 3 , as indicated by double-dotted lines in  FIGS. 37 to 40 . 
     As a result, the center restraining portion  229  is disposed in the foremost position D 3  so as to be more recessed from the shoulder restraining portions  228 L and  228 R. That is, the airbag  215 A comes to have less volume when inflated, and it takes the airbag  215 A a shorter time to complete inflation. With this construction, the left and right shoulder restraining portions  228 L and  228 R restrain shoulders Ms of the small build passenger Mp moving forward firstly, and then the center restraining portion  229  receives a head Mh of the small build passenger Mp softly by the rear plane  229   b.    
     Moreover, upon collision in a condition that the sensor  255  is detecting that a passenger Mp seated in front passenger&#39;s seat is of average build, the control device  254  outputs activating signals only to the electromagnetic solenoid  252  as well as to the inflator  8 , but not to the solenoid  251 . Then the solenoid  252  is activated to pull only the pin  249  out of the wall  246   b  and retract it toward the wall  246   a . At this time, the front end  257   a  of the string member  257  is retained by the second stopper pin  248 , and accordingly, length of the string member  257  released into the airbag body  216  becomes medium. That is, the length of the inner edge of the communication port  223  is medium, too, so that the inner edge  229   a  of the center restraining portion  229  is located in a middle position D 2 , as indicated by single-dotted lines in  FIGS. 38 to 40 . 
     As a result, the center restraining portion  229  is disposed in the middle position D 2  so as to be deeply recessed from the shoulder restraining portions  228 L and  228 R. With this construction, the left and right shoulder restraining portions  228 L and  228 R restrain shoulders Ms of the average build passenger Mp moving forward firstly, and then the center restraining portion  229  receives a head Mh of the passenger Mp softly by the rear plane  229   b . Consequently, the airbag  215 A obtains the same working effects as the airbag  215 . 
     In the airbag  215 A, the inner edge  229   a  of the center restraining portion  229  is contracted or slacked by adjusting the releasing length of the string member  257 . Accordingly, side-viewed shapes of the center restraining portions  229  located in the positions D 1 , D 2  and D 3  upon airbag inflation are generally similar to one another. 
     Moreover, in the airbag  215 A, the string member  257  is not disposed to go across an inner space of the airbag  215 A, unlike the tethers  242  and  243 . Accordingly, the airbag  215 A may be provided with a flow regulating cloth for guiding inflation gas flown in the airbag  215 A forward and rearward, since it is not likely that the flow regulating cloth engages the string member  257 . 
     Although the release adjuster  245  is connected only with the front end  257   a  of the string member  257  in the foregoing embodiment, it will also be appreciated that the rear end  257   b  is also taken out of the airbag  215 A and connected with an assumed adjuster  245  fixed to rear edge part of lower side of the case bottom wall  6   a . It will also be appreciated that the string member  257  is formed into a loop shape, as in the airbag  215 , and wound around the pins  247 ,  248  and  249 . 
     Other than the release adjuster  245  described in the foregoing embodiments, a motor or a pretensioner, which changes lengths of tethers or string member by traction and release, may be adopted as release adjusting mechanism to adjust length of the tethers  242 ,  243  or the string member  257  released into the airbag. Then the release adjusting mechanism is connected to ends of the tethers or string member taken out of the airbag, so that the mechanism is controlled by a control circuit responding to various sensors mounted on the dashboard, roof, a seat or the like of vehicle for monitoring seating position or weight of a passenger. 
     When the airbag can be mounted on various kinds of vehicle in which seating position or physique of a passenger is supposed in a generally limited range, the airbag for front passenger&#39;s seat may be mounted on vehicle with a tether or a string member whose length is fixed. In this case, although the length of a tether or a string member may be adjusted only until the airbag is mounted on vehicle, but not after being mounted, it is advantageous that one kind of airbag may be applied to various kinds of vehicle. 
     Although the outer panel  232  in the airbags  215  and  215 A is formed by a single piece of cloth, or the first base cloth  235 , having such a shape as the left portion  237  defining the left side wall  215   c  and the right portion  238  defining the right side wall  215   d  are joined together in left-right direction, the shape of the outer panel should not be limited thereby. The outer panel may be constructed of a pair of two base cloths split up into a left portion and a right portion. In addition, although the airbags  215  and  215 A are manufactured by sewing up edges of the base cloths  235 ,  240 L and  240 R, connecting means of the edges of the base cloths should not be limited thereby, but adhesive or the like may be used to connect edges of the base cloths. 
     A fourth embodiment of the present invention is now described, by which the second object of the present invention are attainable. As shown in  FIG. 46 , an airbag  340  according to the fourth embodiment is used for an airbag device M 1  for front passenger&#39;s seat, which is also top-mount type, as the airbags  15  and  115 . The airbag device M 1  for front passenger&#39;s seat for which the airbag  340  is used has a similar construction to the aforedescribed airbag device M 1 , and therefore, its description will be omitted by assigning common reference numerals to common members. 
     Referring to  FIGS. 41 to 43 , the airbag  340  is formed into a generally square conical shape when completely inflated by itself, and a top of the conical shape is in a front end of the airbag  340 . The airbag  340  includes an upper side wall  340   a  deployed in upper side, a lower side wall  340   b  deployed in lower side, left and right side walls  340   c  and  340   d  deployed in left and right sides, and a rear wall  340   e  arranged in a rear side, each upon airbag inflation. The airbag  340  includes a protection portion  349  to be deployed in a rear side to face toward a passenger upon airbag inflation, and a vehicle body side portion  341  to be deployed between a dashboard  1  and a wind shield  4  and forward of the protection portion  349  upon airbag inflation. The vehicle body side portion  341  includes a gas inlet port  343  in the vicinity of transverse center thereof and proximate to a front end of the lower side wall  340   b  of the airbag  340  as completely inflated. Around the inlet port  343  are mounting holes  344 , as in the aforedescribed airbags  15 ,  115  and  215 . The airbag  340  is further provided with a tether  356  for keeping the inflated airbag  340  in a predetermined shape. 
     The protection portion  349  includes shoulder restraining portions  350  ( 350 L and  350 R) disposed side by side in left-right direction and projecting rearward in such a manner as to extend vertically, and a recess  352  recessed from upper side to rear side between the left and right shoulder restraining portions  350 L and  350 R. As shown in  FIG. 45 , the shoulder restraining portions  350 L and  350 R are connected to each other at lower parts thereof such that a connected lower part in rear side be generally flat plane, and have a generally V-shape, as viewed as a whole from rearward of vehicle. In the illustrated embodiment, rise of the left and right shoulder restraining portions  350 L and  350 R, and recess of the recess  352  continue forward from the rear side wall  340   e  of the airbag  340 , in such a manner as to enter within an area of the upper side wall  340   a , up to the vicinity of the gas inlet port  343  in the vehicle body side portion  341 . 
     The airbag  340  is formed by joining edges of predetermined shaped base cloths. The airbag  340  includes an upper panel  357  constituting the upper and rear side walls  340   a  and  340   e , and upper parts of the left and right side walls  340   c  and  340   d , and a lower panel  358  constituting the lower side wall  340   b  and lower parts of the left and right side walls  340   c  and  340   d . As shown in  FIG. 44 , the airbag  340  is formed of a pair of first base cloths  359 L and  359 R, as upper panel base cloths, having the same shapes, a second base cloth  364  constituting the lower panel  358 , and two band-shaped tether base cloths  366 . The first base cloths  359 L and  359 R constitute the upper panel  357 . Each of the first base cloths  359 L and  359 R includes an upper portion  360 L/ 360 R and a rear portion  361 L/ 361 R. The upper portions  360 L and  360 R mainly constitute the upper side wall  340   a  and upper parts of the left and right side walls  340   c  and  340   d , of the airbag  340  as completely inflated. The rear portions  361 L and  361 R mainly constitute the rear side wall  340   e  of the airbag  340  as completely inflated. Each of the first base cloths  359 L and  359 R has an elongate shape in which the upper portion  360  and the lower portion  361  are connected to each other at a position to be the vicinity of top of the inflated airbag  340 , and the two base cloths  359 L and  359 R show lateral symmetry. The second base cloth  364  constitutes the lower side wall  340   b  and lower parts of the left and right side walls  340   c  and  340   d , of the airbag  340  as completely inflated, and has a generally hexagonal shape provided with a gas inlet port  343  in a front end thereof. The first and second base cloths  359 L,  359 R and  364 , and the tether base cloths  366  are made from flexible woven fabric of polyester, polyamide or the like. The woven fabric is not coated by coating agent such as silicone, or the like. 
     Below the recess  352  of the protection portion  349  inside the airbag  340  is a communicating portion or communication port  346  communicating the shoulder restraining portions  350 L and  350 R in left-right direction. The communication port  346  is defined by sewn portions which sew up corresponding portions in the upper portions  360 L and  360 R and rear portions  361 L and  360 R of the first base cloths  359 L and  359 R, and by the second base cloth  364 . 
     More specifically, referring to  FIG. 43 , a front upper edge  346   a  of an opening plane of the communication port  346  is defined by a sewn portion  354  formed by sewing up lower inner edges  360   b  of the upper portions  360 L and  360 R of the first base cloths  359 L and  359 R, whereas a rear upper edge  346   b  of the opening plane is defined by a sewn portion  355  formed by sewing up lower inner edges  361   b  of the rear portions  361 L and  361 R of the first base cloths  359 L and  359 R. The communication port  346  is disposed to range from lower side of the protection portion  349  to lower side of the vehicle body side portion  341  in the airbag  340  as completely inflated, and its opening plane is arranged in generally transverse center of the airbag  340  in such a manner as to extend along generally front-rear orientation, when the airbag  340  is completely inflated. As in the aforedescribed airbag  15 , an opening area S 3  of the communication port  343  in a section taken along front-rear direction generally at the center of the gas inlet port  343 , in an completely inflated condition of the airbag  340 , is predetermined ⅕ or greater of a projected area S 4  of a side view of the whole airbag  340  as completely inflated. In the illustrated embodiment, the opening area S 3  of the communication port  346  is generally half of the projected area S 4  of the completely inflated airbag  340 . In the fourth embodiment, too, in order to protect a passenger&#39;s head softly, the opening area S 3  of the communication port  346  is desirably less than ⅘ of the projected area S 4  of the completely inflated airbag  340 . 
     Each of the left and right side walls  340   c  and  340   d  is provided with a vent hole  347 . The tether  356  is formed into a generally band shape, in the illustrated embodiment. One end of the tether  356  is connected to generally transverse and longitudinal center of the lower side wall  340   b  of the airbag  340 , whereas another end is connected to the vicinity of top of the recess  352  as viewed from interior of the airbag  340 , so that the tether  356  is arranged inside the inflated airbag  340  in such a manner as to extend along generally front-rear orientation. 
     Manufacturing of the airbag  340  according to the fourth embodiment is now described. Firstly, the first base cloths  359 L and  359 R are lapped with each other, and the lower inner edges  361   b  of the rear portions  361 L and  361 R are sewn up with sewing yarn. At the same time, an end of one of the tether base cloths  366  is sewn to the vicinity of the top of the lower inner edge  361   b . An end of another tether base cloth  366  is sewn to the center vicinity of the second base cloth  364  with sewing yarn. Subsequently, the lower inner edges  360   b  of the upper portions  360 L and  360 R in the first base cloths  359 L and  359 R are sewn up with sewing yarn. Thereafter, the lapped first base cloths  359 L and  359 R are opened by separating outer edges thereof, and then folded back at the vicinity of joint of the upper portions  360  and  361 , such that the upper portions  360  lap the rear portions  361 . Then, an upper inner edge  361   a  of the rear portion  361 L/ 361 R and an adjacent upper inner edge  360   a  of the upper portion  360 L/ 360 R are sewn up with sewing yarn, respectively. Thereafter, in each of left and right sides, an upper outer edge  360   c  of the upper portion  360 L/ 360 R and an adjacent upper outer edge  361   c  of the rear portion  361 L/ 361 R are sewn up with sewing yarn. 
     Thereafter, the first base cloths  359 L and  359 R are developed by separating remaining unsewn outer edges  360   d ,  360   e  and  361   d  from one another, and the second base cloth  364  is lapped over the first base cloths  359 L and  359 R. At this time, an outer contour of this developed first base cloths  359 L and  359 R is the same as an outer contour of the second base cloth  364 . Subsequently, lower outer edges  361   d  of the rear portions  361 L and  361 R in the first base cloths  359 L and  359 R are sewn to a rear edge  364   a  of the second base cloth  364  with sewing yarn, whereas each of lower outer edges  360   d  of the upper portions  360 L and  360 R in the first base cloths  359 L and  359 R is sewn to left/right edge  364   b / 364   c  of the second base cloth  364  with sewing yarn. Thereafter, front edges  360   e  of the upper portions  360 L and  360 R in the first base cloths  359 L and  359 R are sewn to a front edge  364   d  of the second base cloth  364  with sewing yarn. Then the first base cloths  359 L and  359 R and the second base cloth  364  are reversed inside out from the gas inlet port  343 , such that stitch allowance may not appear on surface. If then another ends of the tether base cloths  366  are taken out from the gas inlet port  343  and sewn to each other in edges thereof, the airbag  340  is completed. 
     In the airbag  340  thus constructed, too, upon airbag inflation, the opening area S 3  of the communication port  346 , which communicates the left and right shoulder restraining portions  350 L and  350 R in left-right direction, is predetermined ⅕ or greater (generally ½, in the foregoing embodiment) of the projected area S 4  of a side view of the airbag  340  as completely inflated. Accordingly, the left and right shoulder restraining portions  350 L and  350 R inflate generally evenly, so that the airbag  340  protects an approaching passenger properly. Thus the second object of the present invention is attained. 
     In the airbag  340 , too, the protection portion  349  includes the shoulder restraining portions  350 L and  350 R and the recess  352  therebetween. With this construction, when the inflated airbag  340  is thrown against a passenger MP, the left and right shoulder restraining portions  350 L and  350 R projecting rearward firstly bump against the vicinities of left and right shoulders MS of the passenger MP, as shown in  FIG. 46 . Thereafter, a head MH of the passenger MP whose shoulders MS are restrained by the shoulder restraining portions  350 L and  350 R enters into the recess  352  provided between the shoulder restraining portions  350 L and  350 R, and then is restrained and suppressed from moving forward. Accordingly, the airbag  340  receives the head MH softly while suppressing reaction force applied thereto. Moreover, in the airbag  340 , too, the opening area S 3  of the communication port  346 , which constitutes the recess  352 , or is located below the recess  352 , is predetermined ⅕ or greater (generally ½, in the foregoing embodiment) of the projected area S 4  of a side view of the airbag  340  as completely inflated. Accordingly, a lower portion of the recess  352  in the protection portion  349  has good cushioning property. With this construction, even if a moving head MH of a passenger MP bumps against the lower portion of the recess  352  in the protection portion  349 , this lower portion of the recess  352  protects the head MH properly. Furthermore, in the airbag  340 , too, the recess  352  is continuously disposed generally along vertical orientation from top side of the protection portion  349 , between the shoulder restraining portions  350 L and  350 R, as shown in  FIG. 45 . Accordingly, even if physique or seating posture of the passenger MP changes a position of head MH in front-rear orientation, the airbag  340  restrains the head MH while having the head MH enter in the recess  352 . Therefore, the airbag  340  is capable of protecting the head MH softly while suppressing reaction force applied thereto. 
     In addition, in the airbag  340  according to the fourth embodiment, edges (the upper edges  346   a  and  346   b ) of an opening plane of the communication port  346  are defined by the sewn portions  354  and  355  sewing up the edges of the first base cloths  359 . Accordingly, an opening area of the communication port  346  is easily changed by changing length of the sewn portions  354  and  355  (ratio of the upper inner edge  360   a / 361   a  and the lower inner edge  360   b / 361   b  in the upper and rear portions  360  and  361  in the first base cloths  359 , length of those edges, or in other words, degree of recess of the lower inner edges  360   b  and  361   b ). As a result, without changing an outer contour of the airbag  340 , a shape of the recess  352  is changed easily, to a deeper shape or shallower shape. 
     Now described is a fifth embodiment of the present invention for attaining the second object of the present invention. As shown in  FIG. 52 , an airbag  369  according to the fifth embodiment is used for an airbag device M 1  for front passenger&#39;s seat, which is a top-mount type, as the airbags  15 ,  115  and  340 . The airbag device M 1  for front passenger&#39;s seat for which the airbag  369  is used has a similar construction to the aforedescribed airbag device M 1 , and therefore, its description will be omitted by assigning common reference numerals to common members. 
     Referring to  FIGS. 47 to 49 , the airbag  369  is formed into a generally square conical shape when completely inflated by itself, and a top of the conical shape is in a front end of the airbag  369 . The airbag  369  includes an upper side wall  369   a  deployed in upper side, a lower side wall  369   b  deployed in lower side, left and right side walls  369   c  and  369   d  deployed in left and right sides, and a rear side wall  369   e  arranged in a rear side, each upon airbag inflation. The airbag  369  includes a protection portion  377  to be deployed in a rear side to face toward a passenger upon airbag inflation, and a vehicle body side portion  370  to be deployed between a dashboard  1  and a wind shield  4  and forward of the protection portion  377  upon airbag inflation. The vehicle body side portion  370  includes a gas inlet port  372  in the vicinity of transverse center thereof proximate to a front end of the lower side wall  369   b  of the airbag  369  as completely inflated. Around the inlet port  372  are mounting holes  373 , as in the aforedescribed airbags  15 ,  115 ,  215  and  340 . The airbag  369  is also provided with a tether  383  for keeping the inflated airbag  369  in a predetermined shape. 
     The protection portion  377  includes two shoulder restraining portions  378 L and  378 R, and a recess  380  located between the left and right shoulder restraining portions  378 L and  378 R, as in the protection portion  349  of the aforedescribed airbag  340 . As in the airbag  340 , the shoulder restraining portions  378 L and  378 R are connected to each other such that a connected lower part in rear side be generally flat plane, and have a generally V-shape, as viewed as a whole from rearward of vehicle. In the protection portion  377 , too, rise of the left and right shoulder restraining portions  378 L and  378 R, and recess of the recess  380  continue forward from the rear side wall  369   e  of the airbag  369 , in such a manner as to enter within an area of the upper side walls  369   a , up to the vicinity of the gas inlet port  372  in the vehicle body side wall  370 . 
     The airbag  369  is formed by joining edges of predetermined shaped base cloths. The airbag  369  includes a front panel  384  constituting the upper, lower, left and right side walls  369   a ,  369   b ,  369   c  and  369   d , and a rear panel  385  constituting the rear side wall  369   e . As shown in  FIG. 50 , the airbag  369  is formed of a first base cloth  386  constituting the front panel  384 , a pair of second base cloths  389 L and  389 R having the same shapes, as rear panel base cloths, and two band-shaped tether base cloths  390 . The second base cloths  389 L and  389 R constitute the rear panel  385 . The first base cloth  386  includes an upper portion  387  and a lower portion  388 . The upper portion  387  mainly constitutes the upper side wall  369   a  and upper parts of the left and right side walls  369   c  and  369   d , of the airbag  369  as completely inflated, and has a generally fan-shape converging toward the gas inlet port  372 . An upper edge  387   c  of the upper portion  387  is so curved that left and right parts of the upper portion  387  project rearward. The upper edge  387   c  vicinity defines the top and rear edge of the airbag  369  as inflated. The rear portion  388  mainly constitutes the lower side wall  369   b , and lower parts of the left and right side walls  369   c  and  369   d , of the airbag  369  as completely inflated, and has a generally fan-shape converging toward a front end thereof, or toward the gas inlet port  372 . The first base cloth  386  is formed into such a shape as the upper portion  387  and the lower portion  388  are connected to each other at a position to be front end vicinity of the inflated airbag  369 . The second base cloths  389 L and  389 R constitute the rear side wall  369   e  of the airbag  369  as completely inflated. Each of the second base cloths  389 L and  389 R has such a curved shape as, in an upper edge  389   b , having transverse center projected upward and having a portion proximate to an inner edge  389   a  recessed. The first and second base cloths  386 ,  389 L and  389 R, and tether base cloths  390  are made of flexible woven fabric of polyester, polyamide or the like. The woven fabric is not coated by coating agent such as silicone, or the like. 
     Below the recess  380  of the protection portion  377  inside the airbag  369  is a communicating portion or communication port  374  that communicates the shoulder restraining portions  378 L and  378 R in left-right direction. Referring to  FIGS. 49 and 50 , upper edge of opening plane of the communication port  374  is defined by the upper portion  387  of the first base cloth  386 , and by a sewn portion  382  which sews up the inner edges  389   a  of the second base cloths  389 L and  389 R, whereas lower edge of the opening plane is defined by the lower portion  388  of the first base cloth  386 . The communication port  374  is disposed to range from lower front end of the protection portion  377  to the vehicle body side portion  370  in the airbag  369  as completely inflated, and its opening plane is arranged in generally transverse center of the airbag  369  as completely inflated in such a manner as to extend along generally front-rear orientation. As in the aforedescribed airbags  15  and  340 , an opening area S 5  of the communication port  374  in a section taken along front-rear direction generally at the center of the gas inlet port  372 , in an completely inflated condition of the airbag  369 , is predetermined ⅕ or greater of a projected area S 6  of a side view of the whole airbag  369  as completely inflated, as shown in  FIG. 49 . In the illustrated embodiment, the opening area S 5  of the communication port  374  is generally half of the projected area S 6  of the completely inflated airbag  369 . In the fifth embodiment, too, in order to protect a passenger&#39;s head softly, the opening area S 5  of the communication port  374  is desirably less than ⅘ of the projected area S 6  of the completely inflated airbag  369 . 
     Each of the left and right side walls  369   c  and  369   d  is provided with a vent hole  375 . The tether  383  is formed into a generally band shape, in the illustrated embodiment. One end of the tether  383  is connected to the vicinity of top and transverse center of the rear side wall  369   e , whereas another end is connected to generally transverse and longitudinal center of the lower side wall  369   b , so that the tether  383  is arranged inside the inflated airbag  369  in such a manner as to extend along generally front-rear orientation. 
     Manufacturing of the airbag  369  according to the fifth embodiment is now described. Firstly, the second base cloths  389 L and  389 R are lapped with each other, and the inner edges  389   a  are sewn up with sewing yarn. At the same time, an end of one of the tether base cloths  390  is sewn to the top vicinity of the inner edge  389   a . Meanwhile, an end of another tether base cloth  390  is sewn to the center vicinity of the lower portion  388  of the first base cloth  386  with sewing yarn. Subsequently, the first base cloth  386  is folded back in a front end vicinity of the inflated airbag  369 , and adjacent left edges  387   a  and  388   a , and right edges  387   b  and  388   b  in the upper and lower portions  387  and  388  are sewn up with sewing yarn, respectively. Thereafter, the first base cloth  386  is developed by separating remaining unsewn edges  387   c  and  388   c  from each other, and the second base cloths  389 L and  389 R in a developed state is lapped over the first base cloth  386 . At this time, a shape of this developed first base cloth  386  is the same as that of the developed second base cloths  389 L and  389 R. Subsequently, an upper edge  387   c  of the upper portion  387  in the first base cloth  386  is sewn to upper edges  389   b  of the second base cloths  389 L and  389 R with sewing yarn, whereas a rear edge  388   c  of the lower portion  388  in the first base cloth  386  is sewn to lower edges  389   c  of the second base cloths  389 L and  389 R with sewing yarn. Thereafter, the first base cloth  386  and the second base cloths  389 L and  389 R are reversed inside out from the gas inlet port  372 , such that stitch allowance may not appear on surface. If then another ends of the tether base cloths  390  are taken out from the gas inlet port  372  and sewn to each other in edges thereof, the airbag  369  is completed. 
     In the airbag  369  of the fifth embodiment, too, upon airbag inflation, the opening area S 5  of the communication port  374 , which communicates the left and right shoulder restraining portions  378 L and  378 R in left-right direction, is predetermined ⅕ or greater (generally ½, in the foregoing embodiment) of the projected area S 6  of a side view of the airbag  369  as completely inflated, as in the aforedescribed airbags  15  and  340 . Accordingly, the left and right shoulder restraining portions  378 L and  378 R inflate generally evenly, so that the airbag  369  protects an approaching passenger properly. Thus the second object of the present invention is attained. 
     In the airbag  369 , too, the protection portion  377  includes the shoulder restraining portions  378 L and  378 R and the recess  380  therebetween. With this construction, when the inflated airbag  369  is thrown against a passenger MP, the left and right shoulder restraining portions  378 L and  378 R projecting rearward firstly bump against the vicinities of left and right shoulders MS of the passenger MP, as shown in  FIG. 52 . Thereafter, a head MH of the passenger MP whose shoulders MS are restrained by the shoulder restraining portions  378 L and  378 R enters into the recess  380  provided between the shoulder restraining portions  378 L and  378 R, and then is restrained and suppressed from moving forward. Accordingly, the airbag  369  receives the head MH softly while suppressing reaction force applied thereto. Moreover, in the airbag  369 , too, the opening area S 5  of the communication port  374 , which constitutes the recess  380 , or is located below the recess  380 , is predetermined ⅕ or greater (generally ½, in the foregoing embodiment) of the projected area S 6  of a side view of the airbag  369  as completely inflated. Accordingly, a lower portion of the recess  380  in the protection portion  377  has good cushioning property. With this construction, even if a moving head MH of a passenger MP bumps against the lower portion of the recess  380  in the protection portion  377 , this lower portion of the recess  380  protects the head MH properly. Furthermore, in the airbag  369 , too, the recess  380  is continuously disposed generally vertically from top side of the protection portion  377 , between the shoulder restraining portions  378 L and  378 R, as shown in  FIG. 52 . Accordingly, even if physique or seating posture of the passenger MP changes a position of head MH in front-rear orientation, the airbag  369  restrains the head MH while having the head MH enter in the recess  380 . Therefore, the airbag  369  is capable of protecting the head MH softly while suppressing reaction force applied thereto. 
     In addition, in the airbag  369  according to the fifth embodiment, too, the rear edge  374   a  in upper inner edge of an opening plane of the communication port  374  is defined by the sewn portion  382  sewing up edges of the second base cloths  389 L and  389 R. Accordingly, an opening area of the communication port  374  is easily changed by changing length of the sewn portion  382 , i.e., length of each of the inner edges  389   a  in the second base cloths  389 L and  389 R. As a result, without changing an outer contour of the airbag  369 , a shape of the recess  380  is changed easily, to a deeper shape or shallower shape.