Airbag and airbag apparatus

An airbag and an airbag apparatus in which a vent hole is in a closed state or a slightly open state until an occupant plunges into the airbag and the vent hole becomes to an open state or a widely open state when the occupant plunges into the airbag. The inside of the airbag 10 is partitioned by inner panels 22A, 22B into a first chamber 1 centrally located and a second chamber surrounding the first chamber 1. A vent hole 18 is formed in a rear panel 14 to allow the communication between the second chamber 2 and the outside of the airbag. A lid member 60 is provided to cover the vent hole 18 from the inside of the rear panel 14. A tether (tethering member) 70 connects the lid member 60 and the inner panels 22A, 22B. When the airbag 10 is inflated, the tether 70 is tensioned to prevent the lid member 60 from moving out of the airbag 10.

TECHNICAL FIELD

The present invention relates to an airbag having a vent hole, which allows gas to be expelled from the inside of the airbag to the outside of the airbag so that an occupant is softly received by the airbag, and a regulating means for regulating gas flow through the vent hole. Further, the present invention relates to an airbag apparatus having the airbag.

BACKGROUND ART

It is well known to form a vent hole in an airbag to allow gas to be expelled from the inside of the airbag through the vent hole when a vehicle occupant plunges into the inflated airbag, whereby the vehicle occupant is softly received and restrained by the airbag.

JP2000-16228A discloses an airbag in which a vent hole is covered by a lid member until the inner gas pressure of the airbag reaches a predetermined value, and the lid member is released to open the vent hole when the inner gas pressure reaches the predetermined value.

In the aforementioned publication, description is made as regard to a driver-side airbag of a vehicle. The airbag disclosed in the aforementioned publication is made by sewing the peripheries of two circular sheet members (panels) together to form one chamber as a whole. The vent hole is formed in the sheet members on a side opposite to the vehicle occupant side of the airbag. The lid member is arranged to cover the vent hole.

In the airbag disclosed in the aforementioned publication, the vent hole is covered by the lid member until the inner gas pressure of the airbag reaches the predetermined value so that the outflow of gas through the vent hole is restricted when the airbag is inflated, thereby rapidly making the inner pressure of the airbag high and thus rapidly inflating the airbag.

As the inner gas pressure of the airbag exceeds the predetermined value, the lid member is released so as to open the vent hole. Therefore, gas flows out from the inside of the airbag through the vent hole when the vehicle occupant plunges into the inflated airbag, whereby the vehicle occupant is softly received and restrained by the airbag

In the publication JP2000-16228A, the vent hole may be opened even in a stage before the occupant plunges into the airbag if the inner pressure of the airbag is increased to the predetermined value or more so that gas is unfortunately flowed out through the vent hole.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide an airbag and an airbag apparatus in which a vent hole is kept in the closed state or the slightly opened state before an occupant plunges into the airbag and the vent hole is opened or widely opened when the occupant plunges into the airbag.

An airbag of the present invention includes a vent hole and a restriction means for restricting outflow of gas through the vent hole, and characterized in that the vent hole is formed in a surface opposite to an occupant facing surface of the airbag in the inflated state or in a side surface of the airbag in the inflated state, that the restriction means comprises: a lid member which is disposed inside the airbag to cover the vent hole; and a tethering member which extends inside the airbag to connect the lid member and said occupant facing surface, and that when the airbag is inflated, the lid member is prevented from moving to outside of the airbag and is overlaid on said vent hole by the tethering member so that the vent hole is closed or slightly opened, and as an occupant collides with the inflated airbag to depress said occupant facing surface, the lid member is pushed out of the airbag through the vent hole by the inner gas pressure of the airbag so as to open or widely open the vent hole.

An airbag apparatus of the present invention comprises the aforementioned airbag of the present invention, a gas generator for supplying gas into the airbag; a retainer to which the airbag is mounted; and a fixing member for fixing the airbag to the retainer.

The airbag apparatus may have such a structure that the fixing member is arranged inside the airbag, the fixing member is provided with an insertion loop through which said tethering member is inserted, said tethering member has one end portion which is connected to said occupant facing surface of the airbag, a midway portion which is inserted through the insertion loop, and the other end portion which continues to one end of said lid member, and the other end of the lid member on the side opposite to the tethering member relative to the vent hole is connected to a portion near the vent hole of the airbag.

DETAILED DESCRIPTION

In an airbag and an airbag apparatus of the present invention, in a stage before an occupant plunges into the airbag when the airbag is inflated, a lid member is prevented from moving out of the airbag by a tethering member so that the lid member is overlaid on a vent hole so that the vent hole is closed or slightly opened. Therefore, the outflow of gas through the vent hole is restricted, thereby rapidly inflating the airbag. Further, this prevents and restricts gas supplied from a gas generator of the airbag apparatus into the airbag from uselessly flowing out of the airbag, thereby allowing the use of a relatively low-power gas generator and thus achieving the reduction in size, weight, and manufacturing cost of the airbag apparatus.

As the occupant plunges into the inflated airbag, an occupant facing surface of the airbag is pressed by the occupant and is thus depressed so that the lid member is allowed to move out of the airbag. Accordingly, the lid member is pressed out of the airbag through the vent hole by the inner gas pressure of the airbag so as to make the vent hole open or widely open, thereby allowing gas to flow out of the airbag through the vent hole. Therefore, the occupant can be received softly and restrained by the airbag

Aspects of the present invention will be described below.

i) An aspect of the present invention may employ such a structure that an insertion loop through which said tethering member is inserted is formed on an inner surface of said surface opposite to the occupant facing surface or on an inner surface of said side surface, wherein the tethering member has one end portion which is connected to said occupant facing surface, a midway portion which is inserted through the insertion loop, and the other end portion which continues to one end (hereinafter, referred to as “free end”) of said lid member, and wherein the other end (hereinafter, referred to as “fixed end”) of the lid member on the side opposite to the tethering member relative to the vent hole is connected to a portion in the vicinity of the vent hole of the airbag.

According to this aspect, as the airbag is inflated, the lid member and a portion (a portion between the insertion loop and the lid member) of the tethering member continued from the lid member continuously extend along the inner surface of the airbag, thereby obtaining improved followability of the lid member relative to the inner surface of the airbag, i.e. improved closability of the vent hole.

ii) Another aspect of the present invention may employ such a structure that a first window is formed in the lid member, and a cover panel is overlaid on the lid member to cover the first window, wherein one end of said cover panel is connected to a portion of the lid member on the tethering member side relative to the first window, and the other end of said cover panel is connected to a portion of the lid member on the side opposite to the tethering member side relative to the first window, wherein a second window is formed in the cover panel at a position not corresponding to the first window, wherein when the airbag is inflated, the lid member is pulled by the tethering member and is thus tensioned and, according to the tension of the lid member, the cover panel is also tensioned to be overlaid on the lid member so that the first window and the second window are both closed, and wherein when the occupant collides with the inflated airbag to depress said occupant facing surface, the tension of the lid member is canceled so that the lid member is pushed out of the airbag through the vent hole by the inner gas pressure of the airbag, and the tension of the cover panel is also cancelled so that the cover panel is spaced apart form the lid member so as to open the first window and the second window.

In this aspect, the first window is formed in the lid member and the first window is covered by the cover panel. In addition, the second window is formed in the cover panel at a position not to be superposed on the first window.

According to this aspect, when the airbag is inflated, the lid member is pulled by the tethering member and is thus tensioned to be overlaid on the vent hole, and the cover panel is also tensioned to be overlaid on the lid member, thereby closing the first window and the second window. Therefore, gas inside the airbag is restricted from flowing out of the airbag through the first window, the second window, and the vent hole so that the airbag is rapidly inflated.

When the occupant collides with the inflated airbag to depress the occupant facing surface of the airbag, the tension of the lid member is cancelled so that the lid member is pushed out of the airbag through the vent hole by gas inner pressure of the airbag and the tension of the cover panel is also canceled so that the cover panel is spaced apart from the lid member, thereby opening the first window and the second window, respectively.

Even though the gas flowing out of the airbag through the vent hole collides with the inner side (the airbag side) of the lid member, the gas flows outside of the lid member (side opposite to the airbag side) through the first opening and the second opening, whereby gas smoothly flows out of the airbag.

In addition, even when the depression amount of the occupant facing surface when the occupant collides with the inflated airbag so that the spacing amount of the lid member from the vent hole is small, enough amount of gas flows out of the airbag because the gas flows out not only through the space between the lid member and the vent hole but also the first window and the second window.

iii) Yet another aspect of the present invention may employ such a structure that the first window and the second window are slits extending in the longitudinal direction of said tethering member.

This can improve the closability of the first window and the second window when the lid member and the cover panel are pulled by the tethering member and are thus tensioned and overlaid on the other.

iv) Yet another aspect of the present invention may employ such a structure that a sub vent hole is formed in said surface opposite to the occupant facing surface or said side surface at a position between the vent hole (hereinafter, referred to as “main vent hole”) and said insertion loop, for allowing the communication between the inside and the outside of the airbag, wherein said lid member is arranged to cover both the main vent hole and the sub vent hole continuously, and wherein a release hole is formed in a portion of said lid member between an area thereof facing the sub vent hole and said tethering member or in a midway portion in the longitudinal direction of said tethering member, and is positioned to correspond to the sub vent hole so as to open the sub vent hole when said lid member is pushed out through the main vent hole.

In this aspect, the sub vent hole for allowing the communication between the inside and the outside of the airbag is formed in the surface opposite to the occupant facing surface or the side surface at a position between the main vent hole and the insertion loop for the tether, the lid member is arranged to cover both the main vent hole and the sub vent hole continuously. Further, the release hole is formed in a portion of the lid member between an area thereof facing the sub vent hole and the tethering member or in a midway portion in the longitudinal direction of the tethering member, and is positioned to correspond to the sub vent hole so as to open the sub vent hole when the lid member is pushed out through the main vent hole.

According to this aspect, when the airbag is inflated, the lid member is pulled by the tethering member and is thus tensioned and overlaid on both the main vent hole and the sub vent hole. Therefore, the outflow of gas through the main vent hole and the sub vent hole is restricted, thereby rapidly inflating the airbag.

When the occupant collides with the inflated airbag and depresses the occupant facing surface of the airbag, the lid member is pushed out of the airbag through the main vent hole by gas inner pressure of the airbag so as to open and widely open the main vent hole. As the lid member is pushed out through the main vent hole, the release hole moves toward the sub vent hole and is superposed on the sub vent hole, thereby opening the sub vent hole. Accordingly, gas flows out through both the main vent hole and the sub vent hole.

Therefore, even when the depression amount of the occupant facing surface when the occupant collides with the inflated airbag so that the spacing amount of the lid member from the vent hole is small, enough amount of gas flows out of the airbag because the gas flows out not only through spaces between the lid member and the vent hole but also the sub vent hole.

v) Yet another aspect of the present invention may employ such a structure that a plurality of the sub vent holes are formed at positions shifted in a direction from said insertion loop to said main vent hole, wherein said release hole is an elongated hole extending in the longitudinal direction of the tethering member.

According to this structure, the larger the depression amount of the occupant facing surface when the occupant collides with the inflated airbag is, the larger the moving distance of the release hole toward the sub vent hole is, so that the release hole is superposed on a larger number of the sub vent holes. The entire opening amount of the sub vent holes is increased so that a larger amount of gas flows out of the airbag.

As the flowing amount of gas out of the airbag is increased, the impact absorbing amount of the airbag is increased.

Therefore, according to this aspect, the impact absorbing amount can be adjusted according to the depression amount of the occupant facing surface of the airbag.

For example, the larger the occupant's body is or the higher the collision speed is, the larger the depression amount of the occupant facing surface when the occupant collides with the inflated airbag is. According to the aspect of claim6, in this case, the entire opening amount of the sub vent hole is increased so that a larger amount of gas flows out of the airbag, thereby sufficiently absorbing impact.

vi) Yet another aspect of the present invention may employ such a structure that at least two vent holes are formed in the surface opposite to the occupant facing surface or the side surfaces, wherein the lid members are provided to cover the vent holes, respectively, and the free end portions of said lid members are connected to said occupant facing surface via the tethering members.

In this case, midway portions in the longitudinal direction of the tethering members are detachably connected to each other by a connecting means, which is adapted to cancel the connection between the tethering members when the inner pressure of the airbag reaches a predetermined value or more.

According to this structure, since the midway portions in the longitudinal direction of the tethering members are connected to each other until the inner pressure of the airbag reaches the predetermined value from the start of inflation of the airbag, the tethering members are restricted from elongating toward the occupant side. Therefore, the tethering members are tensioned before the occupant facing surface of the airbag bulges to a position where is the position at the completion of inflation of the airbag. Accordingly, at an early stage of the inflation of the airbag, the lid member is pulled by the tethering member and is tensioned to close the vent hole so that the airbag is rapidly inflated to have high inner pressure, thereby rapidly inflating the airbag.

After that, as the inner pressure of the airbag reaches the predetermined value or more, the connection between the tethering members by the connecting means is cancelled and the tethering members are thus separated from each other. Accordingly, the restriction of elongation of the tethering members toward the occupant side is cancelled so that the occupant facing surface of the airbag bulges to the position where is the position at the completion of inflation of the airbag.

The tethering members may directly connect the lid member and the occupant facing surface or indirectly connect them via an inner member.

vii) Yet another aspect of the present invention may employ such a structure that an inner member is arranged inside the airbag to connect the occupant facing surface and the surface opposite to the occupant facing surface of the airbag in the inflated state, and said tethering member is connected to said inner member.

In this aspect, the inner member is arranged inside the airbag to connect the occupant facing surface and the surface opposite to the occupant facing surface of the airbag in the inflated state, and the tethering member is connected to the inner member. In this case, according to the inflation of the airbag, the inner member is deployed to elongate toward the occupant side and the lid member is pulled inside the airbag by the inner member via the tethering member so that the lid member is overlaid on the vent hole. As the airbag receives the occupant and the occupant facing surface is thus depressed, the inner member is deflected so that the force pulling the lid member inside the airbag is cancelled and the lid member is spaced apart from the vent hole.

viii) Yet another aspect of the present invention may employ such a structure that said inner member is an inner panel for partitioning the inside of the airbag into a first chamber centrally located and a second chamber surrounding the first chamber, wherein said inner panel is provided with a communication hole formed therein for allowing the communication between the first chamber and the second chamber, wherein said airbag is structured such that gas is first introduced into the first chamber so as to inflate the first chamber and the gas is then introduced from the first chamber to the second chamber through the communication hole so as to inflate the second chamber, and wherein said vent hole is arranged to allow the communication between the second chamber and the outside of the airbag.

In this aspect, gas is first introduced into the first chamber centrally located in the airbag defined by the inner panel as the inner member so that the first chamber is inflated. According to the inflation of the first chamber, the inner panel is deployed to elongate toward the occupant side. The first chamber has a relatively small volume relative to the entire airbag and does not directly communicate with the vent hole so that the first chamber can be extremely rapidly inflated. Therefore, the lid member is pulled inside the airbag by the inner panel via the tethering member so that the lid member is overlaid on the vent hole so as to make the vent hole in the closed or slightly open state at an early stage. As a result of this, gas inside the second chamber is restricted from flowing out of the airbag through the vent hole so that the second chamber can also be rapidly inflated to have high inner pressure, thereby accelerating the inflation of the airbag as a whole.

ix) Yet another aspect of the present invention may employ such a structure that said inner member is a restriction strap of which one end is connected to the occupant facing surface of the airbag and the other end is connected to the surface opposite to the occupant facing surface.

In this aspect, the inner member is a restriction strap of which one end is connected to the occupant facing surface of the airbag and the other end is connected to the surface opposite to the occupant facing surface, thereby simplifying the structure.

x) Yet another aspect of the present invention may employ such a structure that an inner member is arranged to extend across the inside of the airbag to connect side portions of the airbag in the inflated state, and said tethering member is connected to said inner member.

In this aspect, the inner member is arranged to extend across the inside of the airbag to connect side portions of the airbag, thereby allowing greater flexibility in arrangement of the vent hole.

xi) Yet another aspect of the present invention may employ such a structure that said tethering member and said inner member is integrally formed.

In this aspect, the inner member and the tethering member are integrally formed, thereby saving labor for sewing and facilitating the manufacture of the airbag.

Also in this aspect, the airbag senses depression of the airbag (retraction of the occupant facing surface) in a relatively wide area of the occupant facing surface. That is, the inner member extending across the inside of the airbag and connecting the side portions of the airbag can retract according to the depression of the occupant facing surface to cancel the force pulling the lid member inside the airbag so as to open the vent hole even when the occupant plunges into the airbag at a position shifting from the center to depress a portion relatively near the outer periphery of the occupant facing surface.

xii) Yet another aspect of the present invention may employ such a structure that one end of said tethering member is connected to said lid member and the other end of said tethering member is connected to said occupant facing surface.

In this aspect, the lid member and the occupant facing surface can be easily connected regardless of the position of the vent hole.

xiii) Yet another aspect of the present invention may employ such a structure that a gas inlet for introducing gas from a gas generator or a gas generator receiving portion where the gas generator is received is formed in the surface opposite to said occupant facing surface of the airbag, and said the other end of the tethering member is connected to a portion confronting to the gas inlet or the gas generator receiving portion of said occupant facing surface.

In this aspect, as gas is introduced through the gas inlet or the gas generator received at the gas generator receiving portion is actuated to spout gas into the airbag from the gas generator, gas collides with a confronting portion of the occupant facing surface confronting the gas inlet or the gas generator receiving portion so that the confronting portion is rapidly deployed toward the occupant side. Since the tethering member is connected to the confronting portion, the tethering member is also deployed to elongate toward the occupant side. As a result of this, the lid member is pulled and tensioned by the tethering member so that the lid member is overlaid on the vent hole in the early stage of inflation of the airbag.

As mentioned above the lid member is overlaid on the vent hole in the early stage of inflation of the airbag, thereby extremely rapidly inflating the airbag.

xiv) Yet another aspect of the present invention may employ such a structure that said tethering member and said inner member are integrally formed.

According to this structure, it is possible to facilitate the manufacturing process of parts and the entire sewing process of the airbag.

xv) Yet another aspect of the present invention may employ such a structure that a deflection loop through which said tethering member is inserted is provided on the inner surface of said occupant facing surface, wherein one end of said tethering member is connected to said lid member and a midway portion in the longitudinal direction of said tethering member is inserted into said deflection loop.

In this aspect, a larger spacing amount of the lid member from the vent hole can be obtained even when the depression amount of the occupant facing surface is small.

xvi) Yet another aspect of the present invention may employ such a structure that, as said deflection loop(s), a plurality of occupant-side deflection loops are disposed on said occupant facing surface at different positions and a plurality of opposite-occupant-side deflection loops are disposed on the surface opposite to said occupant facing surface, wherein the midway portion of said tethering member is inserted through the occupant-side deflection loops and the opposite-occupant-side deflection loops alternately.

In this aspect, a larger spacing amount of the lid member from the vent hole can be obtained even when the depression amount of the occupant facing surface is small.

According to this aspect, the deflection loops are arranged at different position on the occupant facing surface and the midway portions of the tethering member are inserted into the deflection loops. Therefore, the tethering member is distorted so that the lid member is pushed out of the airbag through the vent hole even when the occupant facing surface is partially retracted.

xvii) Yet another aspect of the present invention may employ such a structure that a pulling member is arranged inside the airbag for pulling a midway portion in the longitudinal direction of said tethering member to the side opposite to the occupant facing surface, wherein said pulling member is connected at its proximal end to the inner surface of the airbag at the side opposite to the occupant facing surface and is provided at its distal end with a guide loop through which the tethering member is inserted, and wherein a midway portion in the longitudinal direction of said tethering member is inserted through the guide loop.

In this aspect, since the proximal end (opposite to the lid member) of the tethering member is pulled toward the occupant side and the midway portion of the tethering member is pulled toward the side opposite to the occupant facing surface by the pulling member when the airbag is inflated, the tethering member is hardly distorted at a stage before the occupant facing surface of the inflated airbag is depressed by the occupant.

xviii) In yet another aspect of the present invention, it is preferable that the lid member does not protrude outside the airbag through the vent hole and is overlaid on the vent hole from the inside of the airbag at the start of inflation of the airbag. Since the vent hole is closed or slightly opened at the start of inflation of the airbag, gas is prevented from flowing out of the airbag through the vent hole during the inflation of the airbag. As a result, the airbag is rapidly inflated.

xix) In yet another aspect of the present invention, it is preferable that the airbag is folded keeping the state that the lid member does not protrude outside the airbag through the vent hole and is overlaid on the vent hole from the inside of the airbag. By folding the airbag in this manner, the lid member is in the state overlaid on the vent hole from the start of inflation of the airbag.

xx) Yet another aspect of the present invention may employ such a structure that an open type vent hole which always allows the communication between the inside and the outside of the airbag is provided.

In the airbag having the open type vent hole, gas flows out of the airbag through the open type vent hole mainly even during the inflation of the airbag. When the airbag is depressed so that the thickness of the airbag is changed, the vent hole with the lid member is also opened so that gas smoothly flows out through both the opened vent hole with the lid member and the open type vent hole.

xxi) Yet another aspect of the present invention may employ such a structure that a fixing member for the airbag which is arranged in the airbag is provided with an insertion loop through which said tethering member is inserted.

In the present invention, the midway portion in the longitudinal direction of the tethering member to be inserted through the aforementioned deflection loop(s) and the guide loop is a midway portion in the longitudinal direction of the tethering member which is on a side opposite to the lid member relative to the insertion loop in case that the tethering member is also inserted through the insertion loop.

Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.FIG. 1andFIG. 2are sectional views of an airbag and an airbag apparatus according to an embodiment,FIG. 3is an exploded perspective view of the airbag and the airbag apparatus, andFIG. 4is a plan view of a rear panel of the airbag.FIG. 1shows a state before an occupant plunges into the airbag andFIG. 2shows a state after the occupant plunges into the airbag.

In this embodiment, the airbag10is a driver-side airbag of a vehicle.

The airbag10comprises a front panel12composing an occupant-side surface, a rear panel14composing an outer surface opposite to the occupant-side surface, first and second inner panels22A,22B as inner members for partitioning the inside of the airbag10into a first chamber1and a second chamber2, a vent hole18for allowing the communication between the second chamber2and the outside of the airbag10, a lid member60for restricting gas from flowing out through the vent hole18, a tether70as a tethering member connecting the lid member60to the inner panel22B, and so on.

The front panel12, the rear panel14, and the first and second inner panels22A,22B are circular woven fabrics, respectively. The front panel12and the rear panel14have substantially the same diameter and their peripheries are sewn together by seam15so as to make an envelope shape. The seam15is provided circularly in an annular shape along the outer periphery of the front panel12and the rear panel14. The seam15is made of sewing yarns, but not limited thereto.

The rear panel14has an inflator (gas generator)-receiving opening16and the aforementioned vent hole18formed therein. The opening16is arranged at the center of the rear panel14. A patch cloth61which is an annular woven fabric is attached to a portion around the opening16from the outside of the airbag10. Numeral62(FIG. 4) designates a seam sewing the patch cloth61and the rear panel14together. The seam62is provided circularly in an annular shape along the outer periphery of the patch cloth61. Around the opening16, bolt through holes20are formed penetrating the patch cloth61and the rear panel14. The vent hole18is disposed between the outer periphery of the patch cloth61and the outer peripheral edge (seam15) of the rear panel14.

The lid member60is overlaid on the vent hole18from the inside of the airbag10. In this embodiment, the lid member60is integrally formed with the tether70.

The first inner panel22A and the second inner panel22B are arranged inside the airbag10. The first and second inner panels22A,22B are arranged substantially coaxially with the front panel12and the rear panel14and the peripheries of the first and second inner panels22A,22B are sewn together by seam23B as first connecting means. By the first and second inner panels22A,22B, the inside of the airbag10is partitioned into the first chamber1centrally located and the second chamber2surrounding the first chamber1. The first chamber1is formed on the inner side of the inner panels22A,22B.

The central portion of the first inner panel22A of the front panel12side (a portion on a distal end side of the inner panel22A in a state that the airbag10is inflated) is sewn to the central portion of the front panel12by a seam23A.

The central portion of the second inner panel22B of the rear panel14side (a portion on a rear end side of the second inner panel22B in the state that the airbag10is inflated) is provided with an inflator-receiving opening24which is formed substantially coaxially with the inflator-receiving opening16of the rear panel14. The inner panel22B is also provided with bolt through holes26formed in a peripheral portion around the opening24at locations corresponding to the bolt through holes20of the rear panel14.

The first and second inner panels22A,22B have communication holes27,28for allowing the communication between the first chamber1and the second chamber2. In this embodiment, the communication holes28of the second inner panel22B are located relatively near the inflator receiving opening24such that the communication holes28are located on extended lines of gas spouting directions of an inflator36which is arranged in the first chamber1through the inflator-receiving openings16,24as will be described later, that is, located to face gas exhaust holes36aof the inflator36. However, the locations of the communication holes27,28are not limited thereto.

It should be noted that reinforcing members such as patches may be attached to peripheral portions of the openings16,24, the communication holes27,28, and/or the vent hole18.

In this embodiment, the aforementioned tether70is integrally formed with the second inner panel22B so that one end (proximal end) portion of the tether70is continued from the outer periphery of the second inner panel22B. The other end (distal end) portion of the tether70functions as the lid member60covering the vent hole18.

However, the tether70may be formed integrally with the first inner panel22A or separately from both the first and second inner panels22A,22B. Further, the tether70may be connected to a portion of the inner panels22A,22B other than the outer peripheries of the inner panels22A,22B. Furthermore, the lid member60may be formed separately from the tether70and attached to the distal end of the tether70.

In this embodiment, the inner surface of the rear panel14is provided with an insertion loop90through which a midway portion of the tether70is inserted. As shown inFIG. 4, the insertion loop90in this embodiment is disposed close to the center side relative to the vent hole18(between the vent hole18and the outer periphery of the patch cloth61). In this embodiment, the insertion loop90is composed of a substantially rectangular small cloth. A pair of side portions of the rectangular small cloth are sewn to the rear panel14by seams91. The tether70is inserted and drawn between the cloth and the panel14from the other pair of sides of the cloth.

As shown inFIG. 4, the lid member60extends in a radial direction of the rear panel14and across vent hole18. The tether70is connected to a central side (proximal end side) of the rear panel14of the lid member60and is inserted into the insertion loop90. At the distal end of the lid member60is sewn to the rear panel14by seam63at a portion near the outer periphery of the rear panel14relative to the vent hole18.

The length of the tether70is set to ensure that, when the airbag10is inflated, the tether70is pulled inside the airbag10by the inner panels22A,22B and is thus tensioned so as to prevent the lid member60from moving out of the airbag10(from being pushed out of the airbag10through the vent hole18by the inner gas pressure of the airbag10) and also to ensure that the lid member60is prevented from being spaced apart from the inner surface of the rear panel14because the lid member60is excessively pulled inside the airbag10by the tether70.

A retainer30for mounting the airbag10has an inflator mounting opening32formed at the center thereof and bolt through holes34formed around the opening32.

The inflator36is substantially cylindrical in shape and has gas exhaust holes36aformed in outer side face of a distal end portion in the axial direction of the cylinder. In this embodiment, the gas exhaust holes36aare four which are equally spaced in the peripheral direction of the inflator36. The inflator36is structured to spout gas through gas exhaust holes36ain radial directions. A flange38for securing the inflator is formed to project from the side periphery of a midway portion in the axial direction of the cylinder as the inflator36. The flange38is provided with bolt through holes40formed therein. The distal end portion of the inflator36is fitted into the inflator mounting opening32.

For mounting the airbag10to the retainer30, the peripheral portion of the inflator-receiving opening24of the second inner panel22B is superposed on the peripheral portion of the inflator-receiving opening16of the rear panel14. Then, the superposed peripheral portions are overlaid on the peripheral portion of the inflator mounting opening32of the retainer30. Stud bolts44of a holding ring42are inserted into the respective bolt through holes26,20,34,40of the second inner panel22B, the rear panel14, the retainer30, and the flange38and nuts46are screwed onto distal ends of the stud bolts44, thereby fixing the second inner panel22B, the rear panel14, and the inflator36to the retainer30.

Therefore, the peripheral portion of the inflator-receiving opening24of the second inner panel22B is connected to the peripheral portion of the inflator-receiving opening16of the rear panel14, the outer peripheries of the first and second inner panels22A,22B are connected to each other, and the central portion of the first inner panel22A is connected to the front panel12.

After that, the airbag10is folded and a module cover48is attached to the retainer30to cover the airbag10in the folded state, thereby composing the airbag apparatus. The airbag10may be previously folded prior to the fixing of the airbag10to the retainer30. The airbag apparatus is mounted to a steering wheel50of an automobile.

In the present invention, it is preferable that the airbag10is folded in a state that the lid member60does not protrudes out of the airbag10through the vent hole18and the lid member60is overlaid on the vent hole18from the inside of the airbag during folding the airbag10. By folding the airbag10in this manner, the lid member60is overlaid on the vent hole18from the initial stage of inflation of the airbag10when the airbag10is inflated. The outflow of gas through the vent hole18is restricted from the initial stage of inflation of the airbag10, thereby rapidly inflating the airbag10.

In the event of a collision of a vehicle in which the airbag apparatus having the aforementioned structure is mounted, the inflator36is actuated to spout gas into the airbag10. The airbag10is inflated by gas to push open a module cover48and is thus deployed into the vehicle cabin.

In the airbag10, gas from the inflator36is first supplied into the first chamber1so that the first chamber1is inflated. According to the inflation of the first chamber1, the first and second inner panels22A,22B are developed to elongate toward the occupant side and the tether70is pulled inside the airbag10by the inner panels22A,22B and is thus tensioned, thereby preventing the lid member60from moving out of the airbag10. Therefore, the lid member60is prevented from being pushed out of the airbag10through the vent hole18by the inner gas pressure of the airbag10and is thus overlaid on the vent hole18to close the vent hole18. Then, gas enters from the first chamber1into the second chamber2through the communication holes27,28so that the second chamber2is inflated.

In the airbag10, the first chamber1has a relatively small volume relative to the entire volume of the airbag10and does not directly communicate with the vent hole18so that the first chamber1can be extremely rapidly inflated. Therefore, the tether70is tensioned at an early stage so as to prevent the lid member60from moving out of the airbag, thereby making the vent hole18in the closed state. Accordingly, the gas inside the second chamber is restricted from flowing out of the airbag through the vent hole18so that the second chamber2can also be rapidly inflated to have high inner pressure. As a result, the inflation of the airbag10as a whole is accelerated.

As mentioned above, in this embodiment, the airbag10is folded keeping the state that the lid member60is overlaid on the vent hole18from the inside of the airbag10, whereby the lid member60is in the state overlaid on the vent hole18from the start of inflation of the airbag10. Since the outflow of gas through the vent hole18is restricted from the start of inflation of the airbag10, the second chamber2can be extremely rapidly inflated.

In this embodiment, since the communication holes28for allowing communication between the first chamber1and the second chamber2are located on extended lines of gas spouting directions of an inflator36disposed inside the first chamber1, that is, located to face the gas exhaust holes of the inflator36, gas is spouted from the gas exhaust holes36atoward the communication holes28when the inflator36is actuated. Accordingly, gas from the inflator36easily enters into the second chamber2through the communication holes28. Therefore, the inflation of the second chamber2is further accelerated.

When the occupant plunges into the thus inflated airbag10, the front panel12of the airbag10is pressed by the occupant and thus depressed toward the rear panel14so that the inner panels22A,22B are distorted as shown inFIG. 2, thereby allowing the lid member60to move out of the airbag10. Therefore, the lid member60is pushed out of the airbag10through the vent hole18by inner gas pressure. As a result, gas flows out of the airbag10through the vent hole18, whereby the occupant is softly received and restrained by the airbag10.

FIG. 5andFIG. 6are sectional views of an airbag and an airbag apparatus according to another embodiment, andFIG. 7is an exploded perspective view of the airbag and the airbag apparatus.FIG. 5shows a state before an occupant plunges into the airbag andFIG. 6shows a state after the occupant plunges into the airbag.

In this embodiment, the airbag10A comprises a front panel12composing an occupant-side surface, a rear panel14composing an outer surface opposite to the occupant-side surface, restriction straps80as inner members inside the airbag10A for connecting the front panel12and the rear panel14, a vent hole18for allowing the communication between the inside and the outside of the airbag10A, a lid member60for restricting gas from flowing out through the vent hole18, a tether70A as a tethering member connecting the lid member60to the restriction strap80, and so on.

Also in this embodiment, the outer peripheries of the front panel12and the rear panel14are sewn together by seam15to compose an outer shell of the envelope-shape airbag10A and the restriction straps80are arranged inside the airbag10A. Also in this embodiment, the rear panel14has an inflator (gas generator)-receiving opening16, the aforementioned vent hole18, and bolt through holes20for securing the rear panel14to a retainer30. The lid member60is overlaid on the vent hole18from the inside of the rear panel14. Also in this embodiment, the lid member60is integrally formed with the tether70A.

In this embodiment, the restriction straps80are composed of a first strap component81on the front panel12side and a second strap component82on the rear panel14side.

In this embodiment, the first strap component81comprises a base portion81adisposed on a central portion of the front panel12and two strap-like portions81b,81bextending radially from the outer periphery of the base portion81a.The base portion81ais a circular woven fabric of which diameter is smaller than that of the front panel12and the strap-like portions81b,81bare positioned opposite to each other across the base portion81a.The base portion81ais disposed substantially coaxially with the front panel12and is sewn to the central portion of the front panel12by seam83.

In this embodiment, the second strap component82comprises a base portion82adisposed on a central portion of the rear panel14and two strap-like portions82b,82bextending radially from the outer periphery of the base portion82a.The base portion82ais a circular woven fabric of which diameter is smaller than that of the rear panel14and the strap-like portions82b,82bare positioned opposite to each other across the base portion82a.The base portion82ahas an inflator-receiving opening82ccorresponding to the inflator-receiving opening16of the rear panel14. The base portion82ais also provided with bolt through holes82dformed in a peripheral portion around the opening82cat locations corresponding to the bolt through holes20.

Distal ends of each pair of the strap-like portions81b,82bof the strap-like components81,82are sewn by seam84.

In this embodiment, one end (proximal end) portion of the tether70A is sewn to a midway portion of one of continuous bodies (hereinafter, the continuous bodies will be sometimes referred to as “restriction straps80”) of the strap-like portions81b,82b.Numeral72designates seam for sewing the end portion of the tether70A to the restriction strap80. Also in this embodiment, the other end portion of the tether70A functions as the lid member60covering the vent hole18.

Also in this embodiment, the inner surface of the rear panel14is provided with an insertion loop90through which a midway portion of the tether70B is inserted. The structure of the insertion loop90is the same as that of the aforementioned embodiments. In this embodiment, the insertion loop90is disposed relatively near the central side of the the rear panel14(an outer periphery of a patch cloth61).

Also in this embodiment, the lid member60extends in a radial direction of the rear panel14and across the vent hole18. The tether70A is continued from the end of the lid member60near a center (proximal end) of the rear panel14and is inserted into the insertion loop90. At the distal end of the lid member60is sewn to the rear panel14at a portion near the outer periphery of the rear panel14relative to the vent hole18.

The length of the tether70A is set to ensure that, when the airbag10A is inflated, the tether70A is pulled inside the airbag10A by the restriction strap80and is thus tensioned so as to prevent the lid member60from moving out of the airbag10A (from being pushed out of the airbag10A through the vent hole18by the inner gas pressure of the airbag10A) and also to ensure that the lid member60is prevented from being spaced apart from the inner surface of the rear panel14because the lid member60is excessively pulled inside the airbag10A by the tether70A.

For mounting the airbag10A to the retainer30, the peripheral portion of the inflator-receiving opening82cof the base portion82ais superposed on the peripheral portion of the inflator-receiving opening16of the rear panel14. Then, the superposed peripheral portions are overlaid on the peripheral portion of the inflator mounting opening32of the retainer30. Stud bolts44of a holding ring42are inserted into the respective bolt through holes82d,20,34,40of the base portion82a,the rear panel14, the retainer30, and the flange38and nuts46are screwed onto distal ends of the stud bolts44, thereby fixing the base portion82a,the rear panel14, and the inflator36to the retainer30.

Therefore, the strap-like portions82bare connected to the rear panel14via the base portion82a,the strap-like portions82b,81bare connected by the seams84, and the strap-like portions81bare connected to the front panel12via the base portion81a.

The airbag10A is different from the aforementioned airbag10as shown inFIG. 1throughFIG. 4by using the restriction straps80as the inner members instead of the inner panels22A,22B and the other components of the airbag10A are the same as those of the airbag10as shown inFIG. 1throughFIG. 4. In addition, the structure of the airbag apparatus comprising this airbag10A has the same structure as the aforementioned embodiment shown inFIG. 1throughFIG. 4. Numerals inFIG. 5throughFIG. 7which are the same as those inFIG. 1throughFIG. 4designate the same components of the aforementioned embodiment as shown inFIG. 1throughFIG. 4.

Also in the embodiment, the airbag10A is folded keeping the state that the lid member60is overlaid on the vent hole18from the inside of the airbag10A.

In the airbag apparatus comprising the airbag10A, the inflator36is actuated to spout gas so as to inflate the airbag10A in the event of a vehicle collision. According to the inflation, the restriction straps80are developed to elongate toward the occupant side and the tether70A is pulled inside the airbag10A by the restriction strap80and is thus tensioned, thereby preventing the lid member60from moving out of the airbag10A. Therefore, the lid member60is prevented from being pushed out of the airbag10A through the vent hole18by the inner gas pressure of the airbag10A and is thus overlaid on the vent hole18to close the vent hole18. As a result, the airbag10A can be rapidly inflated to have high inner pressure, thereby accelerating the inflation of the airbag10A.

Also in this embodiment, the airbag10A is folded keeping the state that the lid member60is overlaid on the vent hole18from the inside of the airbag10A, whereby the lid member60is in the state overlaid on the vent hole18from the start of inflation of the airbag10A. Since the outflow of gas through the vent hole18is restricted from the start of inflation of the airbag10A, the airbag10A can be extremely rapidly inflated.

After that, when the occupant plunges into the thus inflated airbag10A, the front panel12of the airbag10A is pressed by the occupant and thus depressed toward the rear panel14so that the restriction straps80are distorted as shown inFIG. 6, thereby allowing the lid member60to move out of the airbag10A. Therefore, the lid member60is pushed out of the airbag10A through the vent hole18by inner gas pressure of the airbag10A so that the vent hole18is opened. As a result, gas flows out of the airbag10A through the vent hole18, whereby the occupant is softly received and restrained by the airbag10A.

Since the restriction straps80for connecting the front panel12and the rear panel14of the airbag10A are used as the inner members, the airbag10A has a simple structure.

Though the tether70,70A is connected to the inner member of the airbag such as the inner panels22A,22B or the restriction strap in any of the aforementioned embodiments, the tether may be directly connected to the front panel12(the occupant-side surface) of the airbag.FIG. 8andFIG. 9are sectional views of an airbag and an airbag apparatus having such a structure, andFIG. 10is an exploded perspective view of the airbag and the airbag apparatus.FIG. 8shows a state before an occupant plunges into the airbag andFIG. 9shows a state after the occupant plunges into the airbag.

The airbag10B of this embodiment is different from the aforementioned airbag10A as shown inFIG. 5throughFIG. 7in that one of two strap-like portions81bextending from a first strap component81which is attached to the front panel12is arranged to function as a tether70B as the tethering member.

That is, in this embodiment, a strap-like portion81bcomposing a restriction strap80connecting the front panel12and the rear panel14of the airbag10B and the tether70B as the tethering member for connecting the front panel12and the lid member60extend from a base portion81aof the first strap component81.

Also in this embodiment, the base portion81ais sewn to the front panel12and a distal end portion of the strap-like portion81bis connected to a distal end portion of a strap-like portion82bextending from a second strap component82on the rear panel14side by seam84, thereby composing the restriction strap80connecting the front panel12and the rear panel14. In addition, one end (proximal end) portion of the tether70B is connected to the front panel12via the base portion81a.

Also in this embodiment, a lid member60is integrally formed with the other end (distal end) portion of the tether70B.

Also in this embodiment, the inner surface of the rear panel14is provided with an insertion loop90through which a midway portion of the tether70B is inserted. The structure of the insertion loop90is the same as that of any of the aforementioned embodiments. In this embodiment, the insertion loop90is disposed relatively near the central side of the rear panel14(an outer periphery of a patch cloth61).

The midway portion of the tether70B is inserted into the insertion loop90and the distal end portion of the tether70B is drawn to extend along the inner surface of the rear panel14toward the outer periphery of the rear panel14. The lid member60continues from the distal end of the tether70B extends in a radial direction of the rear panel14and across the vent hole18and the distal end of the lid member60is sewn to the rear panel14by seam63at a portion near the outer periphery of the rear panel14relative to the vent hole18.

Also in this embodiment, the length of the tether70B is set to ensure that, when the airbag10B is inflated, the tether70B is pulled toward the occupant side by the front panel12and is thus tensioned so as to prevent the lid member60from moving out of the airbag10B (from being pushed out of the airbag10B through the vent hole18by the inner gas pressure of the airbag10B) and also to ensure that the lid member60is prevented from being spaced apart from the inner surface of the rear panel14because the lid member60is excessively pulled inside the airbag10B by the tether70B.

The other components of the airbag10B are the same as those of the airbag10A as shown inFIG. 5throughFIG. 7. The structure of the airbag apparatus comprising the airbag10B is also the same as that of the embodiment as shown inFIG. 5throughFIG. 7. The folding method of the airbag10B is also the same as that of the airbag10A. Numerals inFIG. 8throughFIG. 10which are the same as those inFIG. 5throughFIG. 7designate the same components of the aforementioned embodiment as shown inFIG. 5throughFIG. 7.

In the airbag apparatus comprising the airbag10B, the inflator36is actuated to spout gas so as to inflate the airbag10B in the event of a vehicle collision. According to the inflation, the tether70B is directly pulled toward the occupant side by the front panel12and is thus tensioned, thereby preventing the lid member60from moving out of the airbag10B. Therefore, the lid member60is prevented from being pushed out of the airbag10B through the vent hole18by the inner gas pressure of the airbag10B and is thus overlaid on the vent hole18to close the vent hole18. As a result, the airbag10B can be rapidly inflated to have high inner pressure, thereby accelerating the inflation of the airbag10B.

Also in this embodiment, the airbag10B is folded keeping the state that the lid member60is overlaid on the vent hole18from the inside of the airbag10B, whereby the lid member60is in the state overlaid on the vent hole18from the start of inflation of the airbag10B. Since the outflow of gas through the vent hole18is restricted from the start of inflation of the airbag10B, the airbag10B can be extremely rapidly inflated.

After that, when the occupant plunges into the thus inflated airbag10B, the front panel12of the airbag10B is pressed by the occupant and thus depressed toward the rear panel14as shown inFIG. 9, thereby allowing the lid member60to move out of the airbag10B. Therefore, the lid member60is pushed out of the airbag through the vent hole18by inner gas pressure so that the vent hole18is opened. As a result, gas flows out of the airbag10B through the vent hole18, whereby the occupant is softly received and restrained by the airbag10B.

Though the insertion loop90for the tether as the tethering member is disposed on the inner surface of the rear panel14in any of the aforementioned embodiments, the insertion loop90for the tether may be disposed on another member inside the airbag, for example, the holding ring42as the fixing member for fixing the rear panel14to the retainer30.

FIG. 11andFIG. 12are sectional views of an airbag and an airbag apparatus having such a structure andFIG. 13is an exploded perspective view of the airbag and the airbag apparatus.FIG. 11shows a state before an occupant plunges into the airbag andFIG. 12shows a state after the occupant plunges into the airbag.

The airbag10C of this embodiment is different from the aforementioned airbag10B as shown inFIG. 8throughFIG. 10in that the insertion loop90disposed on the rear panel14is omitted. In this embodiment, an insertion loop43through which a midway portion of a tether70B as the tethering member is inserted is formed in a holding ring42which is disposed inside the airbag10C to fix the rear panel14to the retainer30.

For details, in this embodiment, the insertion loop43as a projecting piece projecting laterally from the outer periphery of the holding ring42is integrally formed with the holding ring42. The insertion loop43is provided with a tether through hole (no numeral) through which a midway of the tether70B is inserted. The insertion loop43may be formed separately from the holding ring42and then attached to the holding ring42.

The other components of the airbag10C are the same as those of the airbag10B as shown inFIG. 8throughFIG. 10. The structure of the airbag apparatus comprising the airbag10C is also the same as that of the embodiment as shown inFIG. 8throughFIG. 10. The folding method of the airbag10C is also the same as that of the airbag10B. Numerals inFIG. 11throughFIG. 13which are the same as those inFIG. 8throughFIG. 10designate the same components of the aforementioned embodiment as shown inFIG. 8throughFIG. 10.

The actions of the airbag apparatus of this embodiment are the same as the airbag apparatus ofFIG. 8throughFIG. 10.

In any of the aforementioned embodiments, the longer the length of each tether70,70A, or70B is, the larger the opening degree of the vent hole18is because the lid member60moves to a position apart from the vent hole18by a longer distance when the lid member60is pushed out of the airbag10,10A,10B or10C through the vent hole18. On the other hand, the shorter the length of each tether70,70A, or70B is, the smaller the opening degree of the vent hole18is because the lid member60moves to a position relatively near the vent hole18.

That is, by suitably adjusting the length of each tether70,70A, or70B, the opening degree of the vent hole18when the lid member60is pushed out through the vent hole18(i.e. the flowing speed or flowing rate of gas through the vent hole18) can be controlled.

FIG. 14andFIG. 15are sectional views of an airbag and an airbag apparatus according to still another embodiment,FIG. 16is an exploded perspective view of the airbag and the airbag apparatus,FIG. 17ais an enlarged exploded perspective view of a vent hole and a peripheral portion thereof, andFIG. 17bis an enlarged perspective view of the vent hole and the peripheral portion thereof.FIG. 14shows a state before an occupant plunges into the airbag andFIG. 15shows a state after the occupant plunges into the airbag.

The airbag10D of this embodiment is different from the aforementioned airbag10B as shown inFIG. 8throughFIG. 10by a lid member60A which is provided separately from the tethering member to cover the vent hole18from the inside of the airbag10D. The lid member60A and the restriction strap80are connected by a tether70C as the tethering member.

For details, in this embodiment, the lid member60A is a rectangular sheet. The lid member60A is arranged such that the longitudinal direction thereof extends along the radial direction of the rear panel14and the both end portions in the longitudinal direction are sewn to the rear panel14at positions across the vent hole18by seams64.

As shown inFIG. 17a,the distance L2between sewn positions of the lid member60A relative to the rear panel14in the state that the rear panel14is deployed to elongate flatly is shorter than the distance L1between both ends of the lid member60A in the state that the lid member60A is deployed to elongate flatly. Accordingly, as the lid member60A is overlaid on the inner surface of the rear panel14from both ends of the lid member60A, a slack60ais generated about at a middle portion in the longitudinal direction of the lid member60A as shown inFIG. 17b.

The tether70C is sewn at its one end (proximal end) portion to a midway of the restriction strap80by seam72and is sewn at the other end (distal end) portion to a portion about the middle portion in the longitudinal direction of the lid member60A by seam71.

In this embodiment, the length of the tether70C is set to ensure that, when the airbag10D is inflated, the tether70C pulls the lid member60A inside the airbag10D only for an amount corresponding to the aforementioned slack60agenerated at the middle portion in the longitudinal direction of the lid member60A.

According to the aforementioned structure, when the airbag10D is inflated, the lid member60A is pressed against the inner surface of the rear panel14from the both ends in the longitudinal direction thereof toward the middle portion by the inner gas pressure of the airbag10D so that the slack60agenerated at the middle portion is in a state pulled inside the airbag10D by the tether70C. As a result, the lid member60A is prevented from being pushed out of the airbag10D through the vent hold18by the inner gas pressure of the airbag10D so that the lid member60A is overlaid on the vent hole18to close the vent hole18.

The other components of the airbag10D are the same as those of the airbag10B as shown inFIG. 8throughFIG. 10. The structure of the airbag apparatus comprising the airbag10D is also the same as that of the embodiment as shown inFIG. 8throughFIG. 10. The folding method of the airbag10D is also the same as that of the airbag10B. Numerals inFIG. 14throughFIG. 17bwhich are the same as those inFIG. 8throughFIG. 10designate the same components of the aforementioned embodiment as shown inFIG. 8throughFIG. 10.

In the airbag apparatus comprising the airbag10D, the inflator36is actuated to spout gas so as to inflate the airbag10D in the event of a vehicle collision. According to the inflation, the restriction straps80are developed to elongate toward the occupant side and the tether70D is pulled inside the airbag10D by the restriction strap80and is thus tensioned, thereby pulling the lid member60A inside the airbag10D only for an amount corresponding to the slack60a.Therefore, the lid member60is prevented from being pushed out of the airbag10D through the vent hole18by the inner gas pressure of the airbag10D and is thus overlaid on the vent hole18to close the vent hole18. As a result, the airbag10D can be rapidly inflated to have high inner pressure, thereby accelerating the inflation of the airbag10D.

Also in this embodiment, the airbag10D is folded keeping the state that the lid member60A is overlaid on the vent hole18from the inside of the airbag10D, whereby the lid member60A is in the state overlaid on the vent hole18from the start of inflation of the airbag10D. Since the outflow of gas through the vent hole18is restricted from the start of inflation of the airbag10D, the airbag10D can be extremely rapidly inflated.

After that, when the occupant plunges into the thus inflated airbag10D, the front panel12of the airbag10D is pressed by the occupant and thus depressed toward the rear panel14so that the restriction straps80are distorted as shown inFIG. 15, thereby allowing the lid member60A to move out of the airbag10D. Therefore, the lid member60A is pushed out of the airbag10D through the vent hole18by inner gas pressure so that the vent hole18is opened. As a result, gas flows out of the airbag10D through the vent hole18, whereby the occupant is softly received and restrained by the airbag10D.

In this embodiment, the larger the amount of the slack60aof the lid member60A is, the larger the opening degree of the vent hole18is because the lid member60A moves to a position apart from the vent hole18by a longer distance when the lid member60A is pushed out of the airbag10D through the vent hole18. On the other hand, the smaller the amount of the slack60aof the lid member60A is, the smaller the opening degree of the vent hole18is because the lid member60moves to a position relatively near the vent hole18.

That is, by suitably adjusting the amount of the slack60aof the lid member60A as well as the length of the tether70C, the opening degree of the vent hole18when the lid member60A is pushed out through the vent hole18(i.e. the flowing speed or flowing rate of gas through the vent hole18) can be controlled.

Though application examples in which the present invention is applied to a driver-side airbag and airbag apparatus of a vehicle are referred in the aforementioned embodiments, the present invention can be applied to various airbag and airbag apparatuses other than the application examples.

FIGS. 18a,18b,19a,19bshow an example of a front passenger-side airbag to which the present invention is applied.FIG. 18ais a perspective view of the front passenger-side airbag when inflated,FIG. 18bis a vertical sectional view of the inflated airbag,FIG. 19ais a horizontal sectional view showing a state before an occupant plunges into the airbag, andFIG. 19bis a horizontal sectional view showing a state after the occupant plunges into the airbag.

The front passenger-side airbag100is folded and accommodated in a container101and is inflated by an inflator102. The front passenger-side airbag is disposed in an instrument panel103. The open top of the container101is covered by a lid104. Numeral105designates a windshield.

The front passenger-side airbag100is provided with a vent hole110formed in a side surface thereof. The vent hole110is covered by a lid member120from the inside of the airbag. The lid member120extends roughly an anteroposterior direction (a direction connecting an occupant side to the side opposite to the occupant side) of the airbag100and across the vent hole110. An end portion of the lid member120on the side opposite to the occupant side is sewn to the side surface (inner surface) of the airbag100at a position near the rear end side (the side opposite to the occupant side) of the airbag100relative to the vent hole110by seam121. The end on the occupant side of the lid member120continues to a tether130.

Though the lid member110and the tether130are formed integrally with each other in this embodiment, these may be formed separately from each other.

At a position near the occupant relative to the vent hole110, an insertion loop140through which the tether130is inserted is attached to the side surface (inner surface) of the airbag100. The structure of the insertion loop140is the same as that of the insertion loop90of any one of the embodiments as shown inFIG. 1throughFIG. 4. Numeral141designates seams for sewing both end portions of a small cloth composing the insertion loop140to the side surface of the airbag100.

The tether130, of which a midway portion is inserted through the insertion loop140, is sewn at its distal end (the end opposite to the lid member120) to an occupant facing surface100fof the airbag100by seam131.

Also in this embodiment, the length of the tether130is set to ensure that, when the airbag100is inflated, the tether130is pulled toward the occupant side by the occupant facing surface100fof the airbag100and is thus tensioned so as to prevent the lid member120from moving out of the airbag100(from being pushed out of the airbag100through the vent hole110by the inner gas pressure of the airbag100) and also to ensure that the lid member120is prevented from being spaced apart from the side surface of the airbag100because the lid member120is excessively pulled inside the airbag100by the tether130.

Also in this embodiment, the airbag100is folded keeping the state that the lid member120is overlaid on the vent hole110from the inside of the airbag100.

In the airbag apparatus comprising the airbag100, the inflator102is actuated to spout gas so as to inflate the airbag100in the event of a vehicle collision. As shown inFIG. 18bandFIG. 19a,according to the bulge of the occupant facing surface100ftoward the occupant side, the tether130is pulled toward the occupant side by the occupant facing surface100fand is thus tensioned, thereby preventing the lid member120from moving out of the airbag100. Therefore, the lid member120is prevented from being pushed out of the airbag100through the vent hole110by the inner gas pressure of the airbag100and is thus overlaid on the vent hole110to close the vent hole110. As a result, the airbag100can be rapidly inflated to have high inner pressure, thereby accelerating the inflation of the airbag100.

Also in this embodiment, the airbag100is folded keeping the state that the lid member120is overlaid on the vent hole110from the inside of the airbag100, whereby the lid member120is in the state overlaid on the vent hole110from the start of inflation of the airbag100. Since the outflow of gas through the vent hole110is restricted from the start of inflation of the airbag100, the airbag100can be extremely rapidly inflated.

After that, when the occupant plunges into the thus inflated airbag100, the occupant facing surface100fis pressed by the occupant and thus depressed as shown inFIG. 19b,thereby allowing the lid member120to move out of the airbag100. Therefore, the lid member120is pushed out of the airbag100through the vent hole110by inner gas pressure of the airbag100so that the vent hole110is opened. As a result, gas flows out of the airbag100through the vent hole110, whereby the occupant is softly received and restrained by the airbag100.

Also in this embodiment, by suitably adjusting the length of the tether130, the opening degree of the vent hole110when the lid member120is pushed out through the vent hole110(i.e. the flowing speed or flowing rate of gas through the vent hole110) can be controlled.

Also in the front passenger-side airbag100, the vent hole110may be covered by a lid member with a slack like the aforementioned embodiment as shown inFIG. 14throughFIG. 17b.In this case, during the inflation of the airbag100, the lid member is pulled inside the airbag100by the tether130only for an amount corresponding to the slack so as to press the lid member against the vent hole110. When the occupant plunges into the inflated airbag100, the tension of the tether130is released so as to allow the lid member to be pushed out through the vent hole110for an amount corresponding to the slack.

In this case, by suitably adjusting the amount of the slack of the lid member as well as the length of the tether130, the opening degree of the vent hole110when the lid member is pushed out through the vent hole110(i.e. the flowing speed or flowing rate of gas through the vent hole110) can be controlled.

FIG. 20andFIG. 21are sectional views of an airbag apparatus according to still another embodiment,FIG. 20shows a state before an occupant is received, andFIG. 21shows a state when the occupant is received.

An airbag10E of this embodiment comprises a front panel12composing an occupant facing surface, a rear panel14composing an outer surface opposite to the occupant facing surface, a restriction strap200as an inner member which extends across the inside of the airbag10E to connect side portions of the airbag10E to each other, restriction straps201for connecting the front panel12and the rear panel14, a vent hole18allowing communication between the inside and the outside of the airbag10E, a lid member202for restricting the outflow of gas through the vent hole18, and a tether203as a tethering member for connecting the lid member202to the restriction strap200.

Also in this embodiment, the outer peripheries of the front panel12and the rear panel14are sewn together by seam15to compose an outer shell of the envelope-shape airbag10E. The restriction strap200are arranged to extend in the radial direction of the airbag10E and are sewn at its both ends to outer peripheral portions of the front panel12and the rear panel14by the seams15. The restriction strap200prevents or restricts the airbag10E from bulging laterally over a predetermined value when the airbag10E is inflated.

The restriction straps201are disposed such that one ends thereof are connected to a patch cloth204which is sewn to the peripheral portion of an inflator-receiving opening (no numeral) of the rear panel14and the other ends thereof are sewn to a middle portion of the front panel12by seam (no numeral). The restriction straps201prevent or restrict the airbag10E from bulging toward the occupant side over a predetermined value when the airbag10E is inflated.

Though the vent hole18is a circular opening in this embodiment, the configuration of the vent hole is not limited thereto. The vent hole18is disposed at a position not to overlap with a steering wheel50.

The aforementioned lid member202is overlaid on the vent hole18from the inside of the airbag10E. Also in this embodiment, the lid member202is integrally formed with the aforementioned tether203.

Also in this embodiment, the inner surface of the rear panel14is provided with an insertion loop90through which a midway portion of the tether203is inserted. In this embodiment, the insertion loop90is disposed at a position near the outer periphery of the rear panel14relative to the vent hole18as illustrated. The structure of the insertion loop90is the same as that of the aforementioned embodiment as shown inFIG. 1throughFIG. 4. Numeral91designates seams for sewing both end portions of a small cloth composing the insertion loop90to the rear panel14.

The lid member202extends in a radial direction of the rear panel14to cover the vent hole18. One end of the tether203continues to an end of the lid member202near the outer periphery of the rear panel14after inserted into the aforementioned insertion loop90. The end portion of the lid member202near the center of the rear panel14is sewn to the rear panel14at a position near the center of the rear panel14relative to the vent hole18by seam205.

The other end portion of the tether203is sewn to a midway portion of the restriction strap200in the extending direction (the radial direction of the airbag10E) by seam206.

The length of the tether203is set to ensure that, when the airbag10E is inflated and the restriction strap200is tensioned in the radial direction of the airbag10E, the tether203is also pulled inside the airbag10E by the restriction strap200and is thus tensioned so as to prevent the lid member202from moving out of the airbag10E (from being pushed out of the airbag10E through the vent hole18by the inner gas pressure of the airbag10E) and also to ensure that the lid member202is prevented from being spaced apart from the inner surface of the rear panel14because the lid member202is excessively pulled inside the airbag10E by the tether203.

The other components of the airbag10E are the same as those of the airbag10as shown inFIG. 1throughFIG. 4.

Also in the embodiment, the airbag10E is folded keeping the state that the lid member202is overlaid on the vent hole18from the inside of the airbag10E.

When the airbag10E is inflated, as shown inFIG. 20, the restriction strap200is tensioned to extend across the inside of the airbag10E, thereby preventing the airbag10E from excessively bulging laterally, and the restriction straps201are tensioned between the front panel12and the rear panel14, thereby preventing the airbag10E from excessively bulging toward the occupant side.

As shown in the drawings, according to the tension of the restriction strap200, the tether203is pulled inside the airbag10E and is thus tensioned, thereby preventing the lid member202from moving out of the airbag10E. Therefore, the lid member202is prevented from being pushed out of the airbag10E through the vent hole18by the inner gas pressure of the airbag10E and is thus overlaid on the vent hole18to close the vent hole18. As a result, the airbag10E can be rapidly inflated to have high inner pressure, thereby accelerating the inflation of the airbag10E.

Also in this embodiment, the airbag10E is folded keeping the state that the lid member202is overlaid on the vent hole18from the inside of the airbag10E, whereby the lid member202is in the state overlaid on the vent hole18from the start of inflation of the airbag10E. Since the outflow of gas through the vent hole18is restricted from the start of inflation of the airbag10E, the airbag10E can be extremely rapidly inflated.

After that, when the occupant plunges into the thus inflated airbag10E, the front panel12of the airbag10E is pressed by the occupant and thus depressed toward the rear panel14so that the restriction strap200is retracted so as to loosen the tether203as shown inFIG. 21, thereby allowing the lid member202to move out of the airbag10E. Therefore, the lid member202is pushed out of the airbag10E through the vent hole18by inner gas pressure of the airbag10E so that the vent hole18is opened. As a result, gas flows out of the airbag10E through the vent hole18, whereby the occupant is softly received and restrained by the airbag10E.

This airbag10E senses depression of the airbag10E (retraction of the front panel12) in a relatively wide area of the front panel12. That is, the restriction strap200extending across the inside of the airbag10E and connecting the side portions of the airbag10E can retract according to the depression of the front panel12to loosen the tether203so as to cancel the closed state of the vent hole18by the lid member202not only when the occupant plunges into the inflated airbag10E at the center of the front panel12but also when the occupant plunges into the airbag10E at a position shifting from the center to depress a portion relatively near the outer periphery of the front panel12.

In the airbag10E, since the restriction strap200is disposed to extend across the inside of the airbag10E to connect the side portions of the airbag10E, the possibility of location of the vent hole18has been increased.

Though the restriction strap200extends in a straight line across the airbag10E in this embodiment, the restriction strap200may branch to extend in a plurality of direction to extend across the airbag. Two or more restriction straps may be disposed to extend across the airbag. The inner member arranged to extend across the inside of the airbag is not limited to have specific configuration and may be an inner panel which extend across the airbag to partition the inside of the airbag into an occupant-side portion and the other portion. In this case, a lid member may be connected to the inner panel through a tether (tethering member).

In the present invention, as an airbag10F as shown inFIG. 22, a long strap-shape tether300as a tethering member may be suspended alternately between the front panel12and the rear panel14.

In the airbag10F, the front panel12is provided with a plurality of deflection loops301through which a midway portion of the tether300is inserted and which are arranged at positions different from each other and the rear panel14is also provided with a plurality of deflection loop301similar to the deflection loops301which are arranged at positions different from each other. Each of these deflection loops301,302is a substantially rectangular small cloth. A pair of side portions of the rectangular small cloth are sewn to the front panel12or the rear panel14. The tether300is inserted and drawn between the cloth and the panel12or14from the other pair of sides of the cloth.

Also in this embodiment, on the distal end side of the tether300, a lid member303for covering the vent hole18from the inside of the airbag10F is integrally formed with the aforementioned tether300. The lid member303extends in a radial direction of the rear panel14to cover the vent hole18. An end of the lid member303near the center of the rear panel14is sewn to the rear panel14by seam304. The distal end of the tether300continues to an end of the lid member303near the outer periphery of the rear panel14.

Also in this embodiment, the rear panel14is provided with an insertion loop90through which the distal end portion of the tether300is inserted. The insertion loop90is disposed at a position near the outer periphery of the rear panel14relative to the vent hole18. The distal end of the tether300continues to the lid member303after inserted into the insertion loop90. The structure of the insertion loop90is the same as that of any of the aforementioned embodiments.

The other end (opposite to the lid member303) portion of the tether300is slidably inserted and drawn through the deflection loops301on the front panel12and the deflection loop301on the rear panel14alternately and is sewn at its end to the front panel12. However, illustration of the sewn portion of the end of the tether300to the front panel12is omitted inFIG. 22.

The other components of the airbag10F are the same as those of the airbag10as shown inFIG. 1throughFIG. 4.

Also in the embodiment, the airbag10F is folded keeping the state that the lid member303is overlaid on the vent hole18from the inside of the airbag10F.

When the airbag10F is inflated, as shown inFIG. 22, the front panel12bulges toward the occupant side and, according to this bulging, the tether300is tensioned between the front panel12and the rear panel14, thereby preventing the lid member303from moving out of the airbag10F. Therefore, the lid member303is prevented from being pushed out of the airbag10F through the vent hole18by the inner gas pressure of the airbag10F and is thus overlaid on the vent hole18to close the vent hole18. As a result, the airbag10F can be rapidly inflated to have high inner pressure, thereby accelerating the inflation of the airbag10F.

Also in this embodiment, the airbag10F is folded keeping the state that the lid member303is overlaid on the vent hole18from the inside of the airbag10F, whereby the lid member303is in the state overlaid on the vent hole18from the start of inflation of the airbag10F. Since the outflow of gas through the vent hole18is restricted from the start of inflation of the airbag10F, the airbag10F can be extremely rapidly inflated.

After that, when the occupant plunges into the thus inflated airbag10F, the front panel12is pressed by the occupant and thus depressed toward the rear panel14so that the tether300is distorted, not shown but similarly to the state shown inFIG. 2, thereby allowing the lid member303to move out of the airbag10F. Therefore, the lid member303is pushed out of the airbag through the vent hole18by inner gas pressure of the airbag10F so that the vent hole18is opened. As a result, gas flows out of the airbag10F through the vent hole18, whereby the occupant is softly received and restrained by the airbag10F.

In the airbag10F, since the tether300is suspended in zigzag arrangement between the front panel12and the rear panel14, the distortion amount of the tether300as a whole when the front panel12is pressed by the occupant and this depressed toward the rear panel14is greater than that in case not zigzag arrangement. Therefore, enough distortion amount of the tether300, that is, enough protruding amount of the lid member303from the vent hole18can be secured even when the depression amount of the front panel12is small.

Further in the airbag10F, the deflection loops301are arranged at different position on the front panel12. Therefore, the tether300is distorted so that the lid member303is pushed out of the airbag10F through the vent hole18even when the front panel12is partially retracted.

FIGS. 23aand23bare horizontal sectional views showing operational states of an airbag according to still another embodiment.FIG. 23ashows a state before an occupant depresses an occupant-side surface of the inflated airbag andFIG. 23bshows a state that the occupant depresses the occupant-side surface.

An airbag10A of this embodiment is different from the airbag100of the aforementioned embodiment as shown inFIG. 18athroughFIG. 19bby a pulling member400for pulling a midway portion in the longitudinal direction of the tether130to the side opposite to the occupant facing surface100f.

For details, the pulling member400is a cord-like or band-like member in this embodiment. One end portion (proximal end portion) of the pulling member400is sewn to an airbag inner surface100r(hereinafter, this surface will be sometimes referred to as a rear surface100r) opposite to the occupant facing surface100fwhen the airbag100A is inflated, by seam401. Therefore, the other end portion (distal end portion) of the pulling member400is folded back toward the proximal end of the pulling member400and is sewn to a midway portion in the longitudinal direction of the pulling member400by seam402. Accordingly, an annular guide loop403is formed at the distal end of the pulling member400.

A proximal end portion of the tether130is sewn to the occupant facing surface100fby seam131, a middle portion in the longitudinal direction of the tether130is slidably inserted into the guide loop403, and a distal end portion of the tether130is inserted into an insertion loop140attached to a side surface of the airbag100A and continues to a lid member120.

The other components of the airbag100A are the same as those of the airbag100as shown inFIG. 18athroughFIG. 19b.The folding method of the airbag100A is also the same as that of the airbag100.

Also in this embodiment, the airbag100A is folded keeping the state that the lid member120is overlaid on the vent hole110from the inside of the airbag100A, whereby the lid member120is in the state overlaid on the vent hole110from the start of inflation of the airbag100A. Since the outflow of gas through the vent hole110is restricted from the start of inflation of the airbag100A, the airbag100A can be extremely rapidly inflated.

When the airbag100A is inflated, as shown inFIG. 23a,the proximal end portion of the tether130is pulled toward the occupant side by the occupant facing surface100fof the airbag100A and the midway portion in the longitudinal direction of the tether130is pulled toward the side opposite to the occupant side by the rear surface100rof the airbag100A via the pulling member400. Therefore, in a stage before the occupant depresses the occupant facing surface100ftoward the rear surface100rwhen the occupant plunges into the inflated airbag100A, the tether130is hardly distorted so as to improve the closure of the vent hole110by the lid member120.

However, as shown inFIG. 23b,when the occupant plunges into the inflated airbag100A and depresses the occupant facing surface100ftoward the rear surface100r,a portion of the tether130extending from the guide loop403to the occupant facing surface100fis veered out through the guide loop403to the side of the lid member120. This allow the lid member120to move out of the airbag100A so that the lid member120is pushed out of the airbag100A through the vent hole110by the inner gas pressure of the airbag100A so as to open the vent hole110.

Though the vent hole110is formed in only one side surface of the airbag100or100A in any of the aforementioned embodiments shown inFIGS. 18athrough19bandFIGS. 23aand23b,vent holes may be formed in both side surfaces of the airbag in the present invention.

FIG. 24ais a perspective view of an airbag100B having such a structure in the inflated state,FIG. 24bis a vertical sectional view of the inflated airbag100B,FIG. 25ais a horizontal sectional view before an occupant collides with the inflated airbag100B,FIG. 25bis a horizontal sectional view after the occupant collides with the inflated airbag100B, andFIG. 26is a horizontal sectional view just after the airbag100B starts to be inflated.

The airbag100B is also a front passenger-side airbag disposed in an instrument panel (not shown) of a vehicle. In this embodiment, the airbag100B is folded and accommodated in a container101A and can be inflated by an inflator102A.

The airbag100B narrows toward the rear end side (the side opposite to the occupant side) and thus has a triangular shape in a side view and a plan view when the airbag100B is inflated, as shown inFIG. 24bandFIG. 25a.In this embodiment, an inflator mounting portion100gis provided near the rear end of a lower surface of the airbag100B. In this embodiment, an inflator receiving opening (not shown) is formed in the lower surface of the airbag100B near the rear end. The inflator102A is inserted into the airbag100B through the inflator receiving opening.

Numeral106inFIG. 24bdesignates a fixing member for fixing the inflator102A and the airbag100B to the container101A. The fixing member106is arranged to press the inflator102A and the inflator mounting portion100gof the airbag100B against the bottom of the container101A from the inside of the airbag100B. The fixing member106is fixed to the bottom of the container101A by bolts106a.

As shown inFIG. 25a,in this embodiment, vent holes110are formed in left and right side surfaces100h,100mof the airbag100B, respectively. Both the vent holes110are covered by lid members120from the inside of the airbag100B, respectively.

Also in this embodiment, each lid member120extends roughly in an anteroposterior direction (a direction connecting the occupant side to the side opposite to the occupant side) of the airbag100B and across each vent hole110. An end portion of each lid member120on the side opposite to the occupant side is sewn to each side surface100h,100m(inner surface) of the airbag100B by seam121at a position near the rear end side of the airbag100B relative to each vent hole110. The end on the occupant side of each lid member120continues to a tether130.

At a position near the occupant side relative to each vent hole110, an insertion loop140through which the tether130is inserted is attached to the side surface100h,100m(inner surface) of the airbag100B, respectively. Each tether130is arranged to extend to the occupant side from each lid member120and has a midway portion inserted through the insertion loop140.

Also in this embodiment, each lid member120and each corresponding tether130are integrally formed. In this embodiment, the occupant-side ends of the left and right tethers130,130are connected to each other via a mounting piece132. That is, in this embodiment, the left and right lid members120,120, the tethers130,130continued from the lid members120, and the mounting piece132are integrally formed by cutting out them from a sheet of fabric. However, these components120,130,132may be separately formed.

The mounting piece132is sewn to the occupant facing surface100fof the airbag100B by seam131. Therefore, the occupant-side ends of the tethers130are connected to the occupant facing surface100f.

The description will be made as regard to the airbag100B. In the present invention, the occupant-side ends of the tethers130are preferably connected to a portion of the occupant facing surface100fconfronting the aforementioned inflator mounting portion100g,i.e. the inflator102A. As shown inFIG. 25a,in this embodiment, a portion about the middle in the lateral direction of the occupant facing surface100fconfronts the inflator102. The occupant-side ends of the tethers130are connected to the portion about the middle in the lateral direction of the occupant facing surface100f.A line segment Lc inFIG. 25aindicates a center line passing through the middle in the lateral direction of the airbag100B.

Details will be described in the explanation for the operation of an airbag device comprising the airbag100B. The occupant-side ends of the tethers130are connected to the portion confronting the inflator102A of the occupant facing surface100fof the airbag100B, whereby the lid members120can be rapidly overlaid on the respective vent holes110at an early stage of the inflation of the airbag100B.

In the present invention, it is preferable that the connected position K where the occupant-side ends of the tethers130are connected to the occupant facing surface100fis 50 mm or more apart down from the upper end100tof the inflated airbag100B and 100 mm or more apart above from the lower end100bof the airbag100B and is within a range about 200 mm or less from the center (the aforementioned center line Lc) of the occupant facing surface100fin both leftward and rightward directions.

By setting the connected position K of the occupant-side ends of the tethers130to the occupant facing surface100fin this manner, any of parts from the abdominal part to the head of the occupant collides with the connected position K, where the occupant facing surface100fand the occupant-side ends of the tethers130are connected to each other, when the occupant depresses the occupant facing surface100fof the airbag100B even though the seated height and seated position vary to some level from person to person. Accordingly, the tethers130are pushed toward the lid members120so that the lid members120conduct opening operation.

The other components of the airbag100B are the same as those of the aforementioned airbag100as shown inFIG. 18athroughFIG. 19b.The folding method of the airbag100B is also the same as that of the airbag100. Numerals inFIG. 24throughFIG. 26which are the same as those inFIG. 18athroughFIG. 19bdesignate the same components of the aforementioned embodiment as shown inFIG. 18athroughFIG. 19b.

Hereinafter, the actions of the airbag apparatus comprising the airbag100B of this embodiment will be described.

In the event of a vehicle collision, the inflator102A is actuated to spout gas into the airbag100B so as to inflate the airbag100B. As shown inFIG. 25a,according to the bulge of the occupant facing surface100fof the airbag100B toward the occupant side, the tethers130are deployed to elongate toward the occupant side. Accordingly, the lid members120are pulled toward the occupant side by the tethers130, are thus tensioned, and are overlaid on the vent holes110, respectively. Therefore, the vent holes110are closed, thereby restricting the outflow of gas from the airbag100B.

In the airbag100B, the occupant side end portions of the respective tethers130are connected to a portion about the center in the lateral direction of the occupant facing surface100fof the airbag100B confronting the inflator102A. As shown inFIG. 26, as the inflator102A is actuated, gas spouted from the inflator102A collides with the portion about the center in the lateral direction of the occupant facing surface100fso that the portion about the center in the lateral direction of the occupant facing surface100fis rapidly deployed toward the occupant side. Therefore, the tethers130are also deployed to elongate toward the occupant side. As a result of this, the lid members120are pulled and tensioned by the tethers130to close the vent holes110in the early stage of inflation of the airbag100B, thereby extremely rapidly inflating the airbag100.

Also in this embodiment, the airbag100B is folded keeping the state that the lid members120are overlaid on the vent holes110from the inside of the airbag100B, whereby the lid members120are in the state overlaid on the vent holes110from the start of inflation of the airbag100B. Therefore, the outflow of gas through the vent hole110is restricted from the start of inflation of the airbag100B.

After that, when the occupant plunges into the thus inflated airbag100C, the occupant facing surface100fis pressed by the occupant and thus depressed as shown inFIG. 29. Accordingly, the pulling force of the tethers130for pulling the lid members120A toward the occupant side is cancelled so that the tension of the lid members120A is released. Therefore, the lid members120A are pushed out of the airbag100C through the vent holes110by inner gas pressure of the airbag100C so that the vent holes110are opened. As a result, gas flows out of the airbag100C through the vent holes110, whereby the occupant is softly received and restrained by the airbag100C.

In the airbag100B, since both the left and right side surfaces100h,100mof the airbag100B have the vent holes110, respectively, gas substantially laterally evenly flows out of the airbag100B when the respective vent holes110are opened.

In addition, even when the depression amount of the occupant facing surface100fis small when the occupant collides with the inflated airbag100C so that the spacing amounts of the lid members120A from the vent holes110are small, enough amount of gas flows out of the airbag100C because the gas flows out not only through spaces between each lid member120A and each vent hole110but also the first windows122and the second windows151.

FIG. 27ais an exploded plan view of a lid member120A and a cover panel150of an airbag100C according to a different embodiment,FIG. 27bis a plan view of the lid member120A after the cover panel150is attached,FIG. 28is a horizontal sectional view of the airbag100C having the lid member120A in the inflated state,FIG. 29is a horizontal sectional view of the inflated airbag100C in the state after an occupant collides with the airbag100C, andFIG. 30is a perspective view of an XXX portion (around a vent hole110) ofFIG. 29. It should be noted that the illustration of the panel around the bent hole110of the airbag100C is omitted.

Also in the airbag100C, vent holes110are formed in left and right side surfaces100h,100m,respectively and lid members120A are overlaid on vent holes110from the inside of the airbag100C, respectively.

Also in this embodiment, each lid member120A extends roughly in an anteroposterior direction (a direction connecting the occupant side to the side opposite to the occupant side) of the airbag100C and across each vent hole110. An end portion of each lid member120on the side opposite to the occupant side is sewn to each side surface100h,100m(inner surface) of the airbag100C by seam121at a position near the rear end side (the side opposite to the occupant side) of the airbag100C relative to each vent hole110. The end on the occupant side of each lid member120continues to a tether130.

In this embodiment, each lid member120A is provided with a plurality of (three in this embodiment) first windows122formed therein. In this embodiment, each first window122is a slit-like opening extending in the longitudinal direction of the tether130continued from the lid member120A and the first windows122are arranged in parallel to each other and spaced from each other in the width direction of the tether130. Also in this embodiment, each lid member120and each corresponding tether130are integrally formed.

In this embodiment, a cover panel150is overlaid on each lid member120A to cover the first windows122. The cover panel150is a substantially rectangular woven fabric having substantially the same width as the lid member120A.

One end portion of each cover panel150is sewn to each lid member120A by seam123on the side near the tether130relative to the first windows122. The other end portion of each cover panel150is superposed on the end portion of each lid member120A opposite to the tether130relative to the first windows122and is sewn to the side surface100h,100mof the airbag100C together with the end portion of the lid member120A. It should be noted that the other end portion of the cover panel150may be previously sewn to the lid member120A prior to the sewing of the lid member120A to the side surface100h,100mof the airbag100C.

Each cover panel150is provided with a plurality of (four in this embodiment) second windows151formed in portions not facing the first windows122. In this embodiment, each second window151is also a slit-like opening extending in the longitudinal direction of the tether130continued from the lid member120A and the second windows151are arranged in parallel to each other and spaced from each other in the width direction of the tether130.

As shown inFIG. 27b,the windows122,151are arranged such that each first window122faces a panel portion of the cover panel150between adjacent second windows151,151and each second window151faces a panel portion of the lid member120A between adjacent first windows122,122when the cover panel150is overlaid on the lid member120A.

The other components of the airbag100C are the same as those of the aforementioned airbag100B as shown inFIGS. 24athrough26. The folding method of the airbag100C is also the same as that of the airbag100B. Numerals inFIG. 27athroughFIG. 30which are the same as those inFIG. 24athroughFIG. 26designate the same components of the aforementioned embodiment as shown inFIG. 24athroughFIG. 26.

Hereinafter, the actions of the airbag apparatus comprising the airbag100C of this embodiment will be described.

In the event of a vehicle collision, the inflator102A is actuated to spout gas into the airbag100C so as to inflate the airbag100C. As shown inFIG. 28, according to the bulge of the occupant facing surface100fof the airbag100C toward the occupant side, the tethers130are deployed to elongate toward the occupant side. Accordingly, the lid members120are pulled toward the occupant side by the tethers130, are thus tensioned, and are overlaid on the vent holes110, respectively.

As the lid members120A are pulled toward the occupant side by the tethers130, the end portions of the cover panels150on the tether130side are also pulled toward the occupant side, are thus tensioned, and are overlaid on the lid members120A, respectively as shown inFIG. 28. Therefore, the first windows122of each lid member120A are closed by the cover panel150and the second windows151of each cover panel150are closed by the lid member120A.

As a result, the outflow of gas through the vent holes110and the respective windows122,155is prevented, thereby rapidly inflating the airbag100C.

Also in this embodiment, the airbag100C is folded keeping the state that the lid members120A are overlaid on the vent holes110from the inside of the airbag100C, whereby the lid members120A are in the state overlaid on the vent holes110from the start of inflation of the airbag100C. Therefore, the outflow of gas through the vent holes110is restricted from the start of inflation of the airbag100C, thereby extremely rapidly inflating the airbag100C.

Also in the airbag100C, the occupant-side ends of the tethers130are connected to a portion about the center in the lateral direction of the occupant facing surface100fof the airbag100C which confronts the inflator102A. Therefore, as the inflator102A is actuated, gas spouted from the inflator102A collides with the portion about the center in the lateral direction of the occupant facing surface100fso that the portion about the center in the lateral direction of the occupant facing surface100fis rapidly deployed toward the occupant side. Accordingly, the tethers130are also rapidly deployed to elongate toward the occupant side. As a result of this, the lid members120A and the cover panels150are pulled and tensioned by the tethers130to close the vent holes110and first and second windows122,151in the early stage of inflation of the airbag100C, thereby extremely rapidly inflating the airbag100C.

After that, when the occupant plunges into the thus inflated airbag100C, the occupant facing surface100fis pressed by the occupant and thus depressed as shown inFIG. 29. Accordingly, the pulling force of the tethers130for pulling the lid members120A toward the occupant side is cancelled so that the tension of the lid members120A is released. Therefore, the lid members120A are pushed out of the airbag100C through the vent holes110by inner gas pressure of the airbag100C so that the vent holes110are opened. As a result, gas flows out of the airbag100C through the vent holes110, whereby the occupant is softly received and restrained by the airbag100C.

As the tension of the lid members120A is released, the tension of the cover panels150is also released. Therefore, as shown inFIG. 30, each cover panel150is spaced apart from the lid member120A, thereby opening the first windows122and the second windows151.

In this state, gas flowing out of the airbag100C through each vent hole110passes through the first windows122and the second windows151to flow to the outer side (the side opposite to the airbag100C) even when colliding with the inner side (the airbag100C side) of the lid member120A, whereby gas smoothly flows out through the vent holes110.

In addition, even when the depression amount of the occupant facing surface100fis small when the occupant collides with the inflated airbag100C so that the spacing amounts of the lid members120A from the vent holes110are small, enough amount of gas flows out of the airbag100C because the gas flows out not only through spaces between each lid member120A and each vent hole110but also the first windows122and the second windows151.

Though the first windows122and the second windows151are all slit-like openings extending in the longitudinal direction of the tethers130in this embodiment, the configurations of the first windows122and the second windows151are not limited thereto. The number of the windows122,151is not limited to the aforementioned number.

FIG. 31ais a perspective view of an airbag100D according to still another embodiment in the inflated state,FIG. 31bis a vertical sectional view of the airbag100D in the inflated state,FIG. 32is a horizontal sectional view of the airbag100D in the inflated state,FIG. 33is a horizontal sectional view showing a state after an occupant collides with the inflated airbag100D, andFIG. 34is a vertical sectional view showing a state after the occupant collides with the inflated airbag100D.

In the airbag100D, a plurality of (four in this embodiment) small-diameter sub vent holes160are formed in each of left and right side surfaces100h,100mof the airbag100D at a position between each vent hole110(hereinafter, the vent hole110will be sometimes referred to as “main vent hole”) and each insertion loop140.

Each lid member120B of this embodiment extends from the inner side of the airbag100D in an anteroposterior direction (a direction connecting an occupant side to the side opposite to the occupant side) of the airbag100D along the left or right side surface100h,100mof the airbag100D so as to continuously cover both the main vent hole110and the sub vent holes160.

In this embodiment, the sub vent holes160in each side surface100h,100mof the airbag100D are arranged in two rows and two lines so that the positions of the sub vent holes160are shifted in the longitudinal direction and the width direction of each lid member120B.

In this embodiment, the tether130has two release holes133formed in a midway portion in the longitudinal direction of the tether130continued from the occupant side of the lid member120B. The release holes133are elongated holes extending in the longitudinal direction of the tether130and arranged in parallel with each other and spaced apart from each other in the width direction of the tether130.

As shown inFIG. 34, these release holes133are arranged such that the release holes133are positioned to correspond to the sub vent holes160when the tether130moves a predetermined distance toward the main vent hole110according to the movement of the lid member120B to be pushed out through the main vent hole110.

As shown inFIG. 34, each release hole133has such a length that the release hole133is continuously superposed on two sub vent holes160,160which are formed in each side surface100h,100mof the airbag100D to be aligned in the longitudinal direction of the lid member120B.

Also in this embodiment, the airbag100D is folded keeping the state that each lid member120B is overlaid on the main vent hole110and the sub vent holes160from the inside of the airbag100D.

The other components of the airbag100D are the same as those of the aforementioned airbag100B as shown inFIGS. 24 through 26. Numerals inFIGS. 31 through 34which are the same as those inFIGS. 24 through 26designate the same components of the aforementioned embodiment as shown inFIG. 24throughFIG. 26.

Hereinafter, the actions of the airbag apparatus comprising the airbag100D of this embodiment will be described.

In the event of a vehicle collision, the inflator102A is actuated to spout gas into the airbag100D so as to inflate the airbag100D. As shown inFIG. 32, according to the bulge of the occupant facing surface100fof the airbag100D toward the occupant side, the tethers130are deployed to elongate toward the occupant side. Accordingly, the lid members120B are pulled toward the occupant side by the tethers130, are thus tensioned, and are overlaid on the main vent holes110and the sub vent holes160, respectively.

As a result, the outflow of gas through the main vent holes110and the sub vent holes160is restricted, thereby rapidly inflating the airbag100D.

Also in this embodiment, the airbag100D is folded keeping the state that the lid members120B are overlaid on the main vent holes110and the sub vent holes160from the inside of the airbag100D, whereby the lid members120B are in the state overlaid on the main vent holes110and the sub vent holes160from the start of inflation of the airbag100D. Therefore, the outflow of gas through the vent holes110and the sub vent holes160is restricted from the start of inflation of the airbag100D, thereby extremely rapidly inflating the airbag100D.

Also in the airbag100D, the occupant-side ends of the tethers130are connected to a portion about the center in the lateral direction of the occupant facing surface100fof the airbag100D which confronts the inflator102A. Therefore, as the inflator102A is actuated, gas spouted from the inflator102A collides with the portion about the center in the lateral direction of the occupant facing surface100fso that the portion about the center in the lateral direction of the occupant facing surface100fis rapidly deployed toward the occupant side. Accordingly, the tethers130are also rapidly deployed to elongate toward the occupant side. As a result of this, the lid members120B are pulled and tensioned by the tethers130to close the main vent holes110and the sub vent holes160in the early stage of inflation of the airbag100D, thereby extremely rapidly inflating the airbag100.

After that, when the occupant plunges into the thus inflated airbag100D, the occupant facing surface is pressed by the occupant and thus depressed as shown inFIG. 33. Accordingly, the pulling force of the tethers130for pulling the lid members120B toward the occupant side is cancelled so that the tension of the lid members120B is released. Therefore, the lid members120B are pushed out of the airbag100D through the main vent holes110by inner gas pressure of the airbag100D so that the main vent holes110are opened.

As the lid members120B are pushed out through the main vent holes110, the tethers130move toward the main vent holes110, respectively, so that the release holes133move to positions superposed on the sub vent holes160so as to open the sub vent holes160.

As a result, gas flows out of the airbag100D through the main vent holes110and the sub vent holes160, whereby the occupant is softly received by the airbag100D.

In the airbag100D, even when the depression amount of the occupant facing surface100fwhen the occupant collides with the inflated airbag100D is small so that the spacing amounts of the lid members120B from the vent holes110are small, enough amount of gas flows out of the airbag100D because the gas flows out not only through spaces between the lid members120B and the vent holes110but also the sub vent holes160.

In this embodiment, two sub vent holes160are aligned in a direction from the insertion loop140to the main vent hole110in each side surface100m,100mof the airbag100D. As the moving distance of the release holes133toward the main vent holes110is increased, the number of sub vent holes160overlaid on each release hole133is increased, i.e. from 0 to 1, from 1 to 2.

That is, in the airbag100D, as the depression amount of the occupant facing surface100fis increase, the moving distance of each release hole133is increased so that the release holes133are superposed on a larger number of sub vent holes160. Therefore, the entire release amount of the sub vent holes160is increased so that a larger amount of gas flows out of the airbag100D. Accordingly, the larger the amount of gas flowing out of the airbag100D is, the larger the impact absorbing amount of the airbag100D is.

Therefore, the airbag100D can adjust the impact absorbing amount in accordance with the depression amount of the occupant facing surface100f.

For example, the larger the occupant's body is or the higher the collision speed is, the larger the depression amount of the occupant facing surface100fwhen the occupant collides with the inflated airbag100D is. In this case, in the airbag100D, the entire opening amount of the sub vent holes160is increased so that a larger amount of gas flows out of the airbag100D, thereby sufficiently absorbing impact.

The shapes, the numbers, and the arrangements of the sub vent holes160and the release holes133are not limited to the aforementioned structure.

FIGS. 35aand35bare horizontal sectional views of an airbag100E according to still further another embodiment.FIG. 35ashows the airbag100E on the way of inflation of the airbag100E andFIG. 35bshows the airbag100E at the completion of the inflation.

The airbag100E of this embodiment is different form the aforementioned airbag100B as shown inFIGS. 24athrough26in which midway portions in the longitudinal direction of the tethers130,130as left and right tethering members are detachably connected to each other by a tear seam134as a connecting means.

The tear seam134is made by sewing yarn which will break when predetermined tension or more acts on the yarn. In this embodiment, as the inner gas pressure of the airbag100E becomes to a predetermined value or more, the tear seam134breaks to release the connection between the tethers130,130so that the tethers130,130are separated from each other.

The other components of the airbag100E are the same as those of the aforementioned airbag100B as shown inFIGS. 24athrough26. Numerals inFIGS. 35aand35bwhich are the same as those inFIGS. 24athrough26designate the same components of the aforementioned embodiment as shown inFIG. 24athroughFIG. 26.

Also in this embodiment, the airbag100E is folded keeping the state that each lid member120is overlaid on the vent hole110from the inside of the airbag100E.

Hereinafter, the actions of the airbag apparatus comprising the airbag100E of this embodiment will be described.

In the event of a vehicle collision, the inflator102A is actuated to spout gas into the airbag100E so as to inflate the airbag100E. As shown inFIG. 35a,according to the bulge of the occupant facing surface100fof the airbag100E toward the occupant side, the tethers130are deployed to elongate toward the occupant side.

In the airbag100E, the midway portions in the longitudinal direction of the left and right tethers130,130are connected to each other by the tear seam134until the inner pressure of the airbag100E reaches the predetermined value, thereby restricting the tethers130from elongating toward the occupant side. Therefore, the tethers130are tensioned before the occupant facing surface100fof the airbag100E bulges to a position where is the position at the completion of inflation of the airbag100E.

At an early stage of the inflation of the airbag100E, each lid member120is pulled by the tether130and is tensioned to close the vent hole110. As a result, the airbag100E is rapidly inflated to have high inner pressure, thereby accelerating the inflation of the airbag100E.

Also in this embodiment, the occupant-side ends of the tethers130are connected to a portion about the center in the lateral direction of the occupant facing surface100fof the airbag100E which confronts the inflator102A so that the tethers130can be deployed to elongate toward the occupant side by the spouting gas pressure from the inflator102A immediately after the start of actuation of the inflator102A.

Also in this embodiment, the airbag100E is folded keeping the state that the lid members120are overlaid on the vent holes110from the inside of the airbag100E, whereby the lid members120are in the state overlaid on the vent holes110from the start of inflation of the airbag100E. Therefore, the outflow of gas through the vent holes110is restricted from the start of inflation of the airbag100E.

This also accelerates the inflation of the airbag100E.

After that, as the inner pressure of the airbag100E reaches the predetermined value or more, the tear seam134breaks and the tethers130,130are thus separated from each other. Accordingly, the restriction of elongation of the tethers130toward the occupant side is cancelled so that the airbag100E is inflated to the maximum as shown inFIG. 35b.

The actions of the lid members120when the occupant plunges into the thus inflated airbag100E after that are the same as the aforementioned airbag100B.

Though the tear seam134which breaks when receiving predetermined tension or more is used as the connecting means for detachably connecting the midway portions in the longitudinal direction of the tethers130,130to each other in this embodiment, another connecting means may be employed. For example, the tethers130,130are detachably bonded to each other by adhesive agent having such low adhesion force that the adhesive agent is peeled when a predetermined force or more is applied in a peeling direction.

In the present invention, the airbag may have such a structure that three or more vent holes are formed, a lid member is provided for each vent hole, a free end portion of each lid member and an occupant facing surface of an airbag is connected by a tether, and midway portions in the longitudinal direction of the three or more tethers are detachably connected.

Since the aforementioned embodiments are illustrative examples of the present invention, the present invention is not limited to the aforementioned embodiments.

In the present invention, the lid member may have such a structure that the lid member covers partially the vent hole until the airbag is inflated to a predetermined level and the lid member allows the vent hole to widely open when the airbag is inflated to the predetermined volume or more.

Though the vent hole has a circular opening shape in any of the aforementioned embodiments, the shape of the vent hole is not limited thereto and the vent hole may have various shapes such as a slit-like shape.

Though only one vent hole is formed in the airbag in any of the aforementioned embodiments as shown inFIGS. 1 through 23b,two or more vent holes may be formed. Though two vent holes are formed in the airbag in any of the aforementioned embodiments as shown inFIGS. 24athrough35b,three or more vent holes may be formed.

Any of the aforementioned embodiments as shown inFIGS. 1 through 23bmay have a structure similar to the aforementioned embodiment as shown inFIGS. 27athrough30, that is, first windows are formed in the lid member, a cover panel is overlaid on the lid member to cover the first windows, and second windows are formed in the cover panel at positions not corresponding to the first windows.

Any of the aforementioned embodiments as shown inFIGS. 1 through 23bmay have a structure similar to the aforementioned embodiment as shown inFIGS. 31athrough34, that is, sub vent holes are formed in the airbag at a position between the main vent hole and the tether insertion loop, the lid member covers the main vent hole and the sub vent holes continuously and is provided with release holes in a portion thereof on the tether side relative to the sub vent holes or a midway in the longitudinal direction of the tether, such that the release holes are positioned to correspond to the sub vent holes to open the sub vent holes when the lid member is pushed out through the main vent hole.

In the present invention, an open type vent hole which always opens may be formed besides the vent hole(s) to be covered by the lid member(s).

The present application is based on Japanese patent application (Application No. 2006-027355) filed Feb. 3, 2006 and Japanese patent application (Application No. 2006-066041) filed Mar. 10, 2006 which are incorporated herein by reference.