Airbag

An airbag includes a front panel and a rear panel, and the outer peripheries of the front panel and the rear panel are joined together. Each of the front panel and the rear panel has a propeller shape in which a plurality of blade portions extend radially from a center portion such that recessed portions are formed between adjacent blade portions in plan view before the front panel and the rear panel are joined. The plurality of blade portions of the front panel are joined to corresponding recessed portions of the rear panel, and the plurality of blade portions of the rear panel are joined to corresponding recessed portions of the front panel.

TECHNICAL FIELD

The present invention relates to an airbag.

BACKGROUND ART

As illustrated inFIG. 1, an airbag10including a circular front panel11and a circular rear panel12is known, for example. In the airbag10, the outer peripheries13of the front panel11and the rear panel12are joined together.

Patent Documents

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

However, as illustrated inFIG. 2, in the airbag having a circular panel shape, the diameters of both panels need to be increased in order to increase a stroke S of the airbag when fully inflated in a direction toward an occupant P. As a result, the airbag volume increases, and thus, the size and weight of the airbag increases.

In view of the above, the present disclosure provides an airbag that can minimize an increase in airbag volume, while increasing the stroke of the airbag when fully inflated.

Means to Solve the Problem

According to the present disclosure, an airbag includes a front panel and a rear panel, and the outer peripheries of the front panel and the rear panel are joined together. Each of the front panel and the rear panel has a propeller shape in which a plurality of blade portions extend radially from a center portion such that recessed portions are formed between adjacent blade portions in plan view before the front panel and the rear panel are joined. The plurality of blade portions of the front panel are joined to corresponding recessed portions of the rear panel, and the plurality of blade portions of the rear panel are joined to corresponding recessed portions of the front panel.

Effects of the Invention

According to the present disclosure, an airbag capable of minimizing an increase in airbag volume, while increasing the stroke of the airbag when fully inflated can be provided.

MODE FOR CARRYING OUT THE INVENTION

In the following, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, an X-axis, a Y-axis, and a Z-axis are orthogonal to one another. An X-axis direction, a Y-axis direction, and a Z-axis direction respectively indicate a direction parallel to the X-axis, a direction parallel to the Y-axis, and a direction parallel to the Z-axis. An XY plane, a YZ plane, and a ZX plane respectively indicate a plane including the X-axis and the Y-axis, a plane including the Y-axis and the Z-axis, and a plane including the Z-axis and the X-axis.

FIG. 3is a plan view of a front panel20of an airbag101according to a first embodiment.FIG. 4is a plan view of a rear panel40of the airbag101according to the first embodiment.FIG. 5,FIG. 6, andFIG. 7are a front view, a top view, and a side view of the airbag101when fully inflated, respectively, according to the first embodiment. The airbag101includes the front panel20and the rear panel40. The airbag101is an inflatable and deployable component in which the outer peripheries of the front panel20and the rear panel40are joined together. The airbag101is inflated and deployed to restrain the movement of an occupant of a vehicle.

The airbag101is housed in a folded state before inflation and deployment. At the time of vehicular collision, the airbag101housed in the folded state is supplied with gas from an inflator. As a result, the airbag101is inflated and deployed.

The airbag101is an airbag for a driver's seat, and is housed in a steering wheel70. However, the airbag according to the present invention is not limited to an airbag for a driver's seat, and may be an airbag for a front passenger seat or a rear seat.

FIG. 3is a plan view of the front panel20before being joined to the rear panel40. The front, panel20is a panel on the occupant side, and includes a center portion21that faces the occupant when the airbag101is inflated and deployed.

The front panel20is made of a base fabric having a propeller shape, in which a plurality of blade portions24through26extend radially from the center portion21such that recessed portions are formed between adjacent blade portions in plan view before the front panel20is joined to the rear panel40. InFIG. 3, the front panel20includes the three blade portions24through26and three recessed portions37through39. The first recessed portion37is formed between the first blade portion24and the third blade portion26, the second recessed portion38is formed between the first blade portion24and the second blade portion25, and the third recessed portion39is formed between the second blade portion25and the third blade portion26.

In the present embodiment, the center portion21represents a circular area centered at a center point22and having a diameter ϕA. The plurality of blade portions24through26extend radially from the center portion21at equal intervals of an angle θ1(120° inFIG. 3).

FIG. 4is a plan view of the rear panel40before being joined to the front panel20. The rear panel40is a panel on the side opposite to the occupant, and includes a center portion41that has an opening60. The inflator is inserted into the opening60for attachment.

The rear panel40is made of a base fabric having a propeller shape, in which a plurality of blade portions44through46extend radially from the center portion41such that recessed portions are formed between adjacent blade portions in plan view before the rear panel40is joined to the front panel20. InFIG. 4, the rear panel40includes the three blade portions44through46and three recessed portions57through59. The number of the blade portions44through46of the rear panel40is the same as the number of the blade portions22through26of the front panel20, and the number of the recessed portions57through59of the rear panel40is the same as the number of the recessed portions37through39of the front panel20. The fourth recessed portion57is formed between the fourth blade portion44and the fifth blade portion45, the fifth recessed portion58is formed between the fifth blade portion45and the sixth blade portion46, and the sixth recessed portion53is formed between the sixth blade portion46and the fourth blade portion44.

In the present embodiment, the center portion41represents a circular area centered at a center point42and having a diameter ϕB. The plurality of blade portions44through46extend radially from the center portion41at equal intervals of an angle θ2(120° inFIG. 4). A plurality of fixing holes61for fixing the rear panel40to a retainer (not illustrated) are formed around the opening60of the center portion41.

InFIG. 3andFIG. 4, the plurality of portions24through26of the front panel20are joined to the recessed portions57through59of the rear panel40, respectively, and the plurality of blade portions44through46of the rear panel40are joined to the recessed portions37through39of the front panel20, respectively. That is, the first blade portion24is joined to the fourth recessed portion57, the second blade portion25is joined to the fifth recessed portion58, and the third blade portion26is joined to the sixth recessed portion59. Further, the fourth blade portion44is joined to the first recessed portion37, the fifth blade portion45is joined to the second recessed portion36, and the sixth blade portion46is joined to the third recessed portion39.

By joining the outer periphery of the propeller-shaped front panel20to the outer periphery of the propeller-shaped rear panel40, the airbag101is formed.FIG. 5throughFIG. 7denote the airbag101when fully inflated. The stroke of the airbag101when fully inflated in the direction facing the occupant can be increased by increasing the length in the radial direction of each of the blade portions24through26and44through46. Because the plurality of blade portions of the panels fit into the corresponding recessed portions of the panels, an increase in the volume of the airbag101can be minimized even when the length in the radial direction of each of the blade portions24through26and44through46is increased.

Therefore, in the airbag101according to the present embodiment, an increase in airbag volume can be minimized, and also the stroke of the airbag101when fully inflated can be increased. In addition, because an increase in airbag volume can be minimized even when the stroke of the airbag101when fully inflated is increased, the outer shape of the airbag101in the folded state can be decreased. Thus, the airbag101can be compactly housed. Further, because an increase in airbag volume can be minimized, the stroke of the airbag101when fully inflated can be increased without using an inflator capable of supplying a large amount of gas.

InFIG. 3andFIG. 4, the outer periphery of the front panel20and the cuter periphery of the rear panel40may be joined by being sewn together with a thread. The outer peripheries of the front and rear panels are joined together, such that a joining line36formed along the outer peripheral edge of the front panel20coincides with a joining line56formed along the outer peripheral edge of the rear panel40. In a case where the outer periphery of the front panel20and the cuter periphery of the rear panel40are joined by being sewn together, the joining lines36and56correspond to sewing lines.

InFIG. 3, the joining line36contacts contact points23a,23b, and23cof a circular outer edge23of the center portion21. Further, a peripheral portion35is formed between the outer peripheral edge and the joining line36of the front panel20. InFIG. 4, the joining line56contacts contact points43a,43b, and43cof a circular outer edge43of the center portion41. Further, a peripheral portion55is formed between the outer peripheral edge and the joining line56of the rear panel40. The joining line36and the joining line56are joined together such that the peripheral portions35and55are located inside the airbag101.

In the present embodiment, the outer periphery of the front panel20and the outer periphery of the rear panel40have the same peripheral length, and are joined together. Therefore, the front panel20and the rear panel40do not readily twist when joined together. InFIG. 3andFIG. 4, the peripheral length represents the length of the joining lines36and56. Further, in the present embodiment, the plurality of blade portions24through26of the front panel20have the same outer peripheral shape, and the plurality of blade portions44through46have the same outer peripheral shape. Therefore, the front panel20and the rear panel40do not readily twist when joined together.

A maximum length F1in the radial direction of each of the blade portions24through26illustrated inFIG. 3is preferably greater than a maximum length D1in the width direction perpendicular to the radial direction. For convenience, in the example illustrated inFIG. 3, the maximum length F1of the first blade portion24represents the shortest distance between a portion28, where the first blade portion24contacts the cancer portion21, and a tip portion27in the radial direction of the first blade portion24. The same applies to the maximum length F1of each of the second blade portion25and the third blade portion26. For convenience, in the example illustrated inFIG. 3, the maximum length D1of the first blade portion24represents the shortest distance between one outer edge portion29and the other outer edge portion30of a middle portion whose length in the width direction perpendicular to the radial direction becomes maximum. The outer edge portions29and30are located on the joining line36. The same applies to the maximum length D1of each of the second blade portion25and the third blade portion26.

Similarly, a maximum length F2in the radial direction of each of the blade portions44through46illustrated inFIG. 4is preferably greater than a maximum length D2in the width direction perpendicular to the radial direction. For convenience, in the example illustrated inFIG. 4, the maximum length F2of the fourth blade portion44represents the shortest distance between a portion48, where the fourth blade portion44contacts the center portion41, and a tip portion47in the radial direction of the fourth blade portion44. The same applies co the maximum length F2of each of the fifth blade portion45and the sixth blade portion46. For convenience, in the example illustrated inFIG. 4, the maximum length D2of the fourth blade portion44represents the shortest distance between one outer edge portion49and the other outer edge portion50of a middle portion whose length in the width direction perpendicular to the radial direction becomes maximum. The outer edge portions49and50are located on the joining line56. The same applies to the maximum length D2of each of the fifth blade portion45and the sixth blade portion46.

As described above, by setting the lengths F1to be longer than the lengths D1and lengths F2to be longer than the lengths D2, an increase in airbag volume can be minimized, and also the stroke of the airbag101when fully inflated can be readily increased.

In the examples ofFIG. 3andFIG. 4, each of the blade portions24through26and44through46includes a middle portion whose length in the width direction perpendicular to the radial direction becomes maximum, and also includes a tip portion in the radial direction. Specifically, the plurality of blade portions24through26include tip portions27,33, and34, respectively. The plurality of blade portions44through46include tip portion47,53, and54, respectively. Further, the middle portion of each of the blade portions24through26and44through46includes a pair of outer edge portions that are bent so as to project in the width direction perpendicular to the radial direction. For example, the middle portion of the first blade portion24includes the pair of outer edge portions29and30that project in opposite directions to each other. The middle portion of the fourth blade portion44includes the pair of outer edge portions49and50that project in opposite directions to each other.

The pair of outer edge portions29and30of the front panel20is joined to a pair of outer edge portions50and84. The outer edge portions50and84are located at the recessed portion57formed between the adjacent blade portions44and45of the rear panel40. A pair of outer edge portions80and81are joined to a pair of outer edge portions85and86. The outer edge portions85and86are located at the recessed portion58formed between the adjacent blade portions45and46of the rear panel40. A pair of outer edge portions82and83is joined to a pair of outer edge portions87and49. The outer edge portions87and49are located at the recessed portion59formed between the adjacent blade portions46and44of the rear panel40.

As described above, the front panel20and the rear panel40are joined together such that the outer edge portions of the front panel20coincide with the cuter edge portions of the rear panel40. Accordingly, as illustrated inFIG. 6, a maximum width portion wider than the center portion21can be formed. Thus, even when the head of an occupant P does not directly contact the center portion21of the airbag101(that is, when the head of the occupant P contacts the left or right side of the airbag101), the occupant P can be restrained by the maximum width portion wider than the center portion21of the airbag101.

The length D1in the width direction of the middle, portion of each of the blade portions24through26illustrated inFIG. 3is preferably greater than a length E1in the width direction of a portion28where each of the blade portions24through26contacts the center portion21. For convenience, in the example illustrated inFIG. 3, the length E1represents the shortest distance between a pair of intersections31and32where a tangent line to the circular center portion21at the portion28crosses the joining line36.

Similarly, the length D2in the width direction of the middle portion of each of the blade portions44through46illustrated inFIG. 4is preferably greater than a length E2in the width direction of a portion48where each of the blade portions44through46contacts the center portion41. For convenience, in the example illustrated inFIG. 4, the length E2represents the shortest distance between intersections51and52where a tangent line to the circular center portion41at the portion48crosses the joining line56.

The maximum width portion wider than the center portion21can be readily formed by setting the length D1to be longer than the length E1in each of the blade portions24through26of the front panel20and setting the length D2to be longer than the length E2in each of the blade portions44through46of the rear panel40.

For example, a length b1from the middle portion to the tip portion is set to be less than a length a1from the center portion21to the middle portion in each of the blade portions24through26of the front panel20. Further, a length a2from the middle portion to the tip portion is set to be greater than a length b2from the center portion41to the middle portion in each of the blade portions44through46of the rear panel40. With the above-described dimension relationship, at maximum inflation of the airbag101as illustrated inFIG. 6, a stroke length α on the occupant P side relative to the maximum width portion can be made greater than a stroke length β on the side opposite to the occupant P relative to the maximum width portion.

Accordingly, a center of gravity100of the airbag101can be positioned on the negative Z-side relative to the maximum width portion.

Alternatively, the length b1from the middle portion to the tip portion may be set to be greater than the length a1from the center portion21to the middle portion in each of the blade portions24through26of the front panel20. Further, the length a2from the middle portion to the tip portion may be set to be less than the length b2from the center portion41to the middle portion in each of the blade portions44through46of the rear panel40. With the above-described dimension relationship, at maximum inflation of the airbag101, the stroke length α of the airbag101on the occupant P side relative to the maximum width portion can be made less than the stroke length β on the side opposite to the occupant P relative to the maximum width portion. Accordingly, the center of gravity100of the airbag101can be positioned on the positive Z-side relative to the maximum width portion.

Alternatively, the length b1from the middle portion to the tip portion may be set to be equal to the length a1from the center portion21to the middle portion in each of the blade portions24through26of the front panel20. Further, the length a2from the middle portion to the tip portion may be set to be equal to the length b2from the center portion41to the middle portion in each of the blade portions44through46of the rear panel40. With the above-described dimension relationship, at maximum inflation of the airbag101, the stroke length α on the occupant P side relative to the maximum width portion can be made equal to the stroke length β on the side opposite to the occupant P relative to the maximum width portion. Accordingly, the center of gravity100of the airbag101can be positioned in the vicinity of the maximum width portion.

The center of gravity100illustrated inFIG. 6does not necessarily indicate an accurate location of the center of gravity.

Further, at least one blade portion of the plurality of blade portions44through46of the rear panel40illustrated inFIG. 4may include at least one vent hole401on the side closer to the center portion41than to the middle portion of the at least one blade portion. Accordingly, gas in the airbag101can be discharged from the side of the airbag101opposite to the occupant P. For example, one or more vent holes401may be formed in the center portion41.

Further, instead of or in addition to the at least one vent hole401formed in the rear panel40, at least one vent hole201may be formed in the front panel20illustrated inFIG. 3. In this case, at least one blade portion of the plurality of blade portions24through26of the front panel20may include at least one vent hole201on the side closer to the tip portion than to the middle portion of the at least one blade portion. Accordingly, gas in the airbag101can be discharged from the side of the airbag101opposite to the occupant P. For example, one or more vent holes201may be formed in an area between the middle portion and the tip portion of the at least one blade portion.

Further, as illustrated inFIG. 8, at least one tether75may be provided in the airbag101. A connection portion71of the tether75is connected to the center portion21of the front panel20, and another connection portion71is connected to the center portion41of the rear panel40. Accordingly, the center portion21, with which the occupant P may make contact when the airbag101is fully inflated, can be formed in a planar shape or formed in a recessed shape in which the center portion21is recessed toward the inside of the airbag101.

FIG. 9is a perspective view of a panel of an airbag according to a second embodiment. A description of a configuration and advantageous effects of the second embodiment, similar to those of the first embodiment, will be omitted.

In the first embodiment, each of the front panel and the rear panel is formed of one base fabric. However, one or both of the front panel and the rear panel may be formed of a plurality of base fabrics. In the second embodiment illustrated inFIG. 9, a rear panel40is formed of three base fabrics, and each of three blade portions44through46is formed of one base fabric. By dividing the rear panel40into the three blade portions44through46, the orientation of threads in each of the base fabrics can be changed.

FIG. 10is a plan view of a front panel of an airbag according to a third embodiment.FIG. 11is a plan view of a rear panel of the airbag according to the third embodiment. A description of a configuration and advantageous effects of the third embodiment, similar to those of the above-described embodiments, will be omitted.

In the first embodiment, each of the front panel and the rear panel includes the three blade portions. However, each of the front panel and the rear panel does not necessarily include the three blade portions, and may include any number of blade portions other than 3. As the number of blade portions increases, the outer shape of the airbag as viewed from the front becomes close to a circle. For example, the airbag including the three blade portions according to the first embodiment is formed in a hexagonal shape as viewed from the front (seeFIG. 5). If the airbag includes two blade portions, the airbag is formed in a square shape as viewed from the front. If the airbag includes four blade portions, the airbag is formed in an octagonal shape as viewed from the front.

InFIG. 10, a front panel120is made of a fabric having a propeller shape, in which four blade portions121through124extend radially from the center portion such that recessed portions are formed between adjacent blade portions in plan view before the front panel120is joined to a rear panel. In the example ofFIG. 10, the front panel120includes the four blade portions121through124and four recessed portions125through128.

InFIG. 11, a rear panel140is made of a fabric having a propeller shape, in which four blade portions141through144extend radially from the center portion such that recessed portions are formed between adjacent blade portions in plan view before the rear panel140is joined to the front panel120. In the example ofFIG. 11, the rear panel140includes the four blade portions141through144and four recessed portions145through148. The number of the blade portions141through144is the same as the number of the blade portions121through124of the front panel120, and the number of the recessed portions145through148is the same as the number of the recessed portions125through128of the front panel120.

The plurality of blade portions121through124of the front panel120are joined to the corresponding recessed portions145through148of the rear panel140. The plurality of blade portions141through144of the rear panel140are joined to the corresponding recessed portions125through126of the front panel120.

Accordingly, the airbag according to the third embodiment can minimize an increase in airbag volume, while increasing the stroke of the airbag when fully inflated.

Although specific embodiments have been described above, the present invention is not limited to the above-described embodiments. Variations, modifications, and substitutions of a part or all of the embodiments may be made without departing from the scope of the present invention.

For example, if the external shape of an airbag when fully inflated is not required to be uniform, a plurality of blade portions of a front panel do not necessarily have the same outer peripheral shape, and a plurality of blade portions of a rear panel do not necessarily have the same outer peripheral shape. For example, if the blade portions of the airbag have the same shape, the airbag inflates uniformly and symmetrically in the circumferential direction as viewed from the front. Conversely, if the blade portions have different shapes, the airbag can inflate asymmetrically in the circumferential direction as viewed from the front.

This application is based on and claims priority to Japanese Patent Application No. 2018-105098, filed on May 31, 2018, the entire contents of which are incorporated herein by reference.

DESCRIPTION OF THE REFERENCE NUMERALS