Patent Publication Number: US-2023132711-A1

Title: Vehicle airbag apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority from Japanese Patent Application No. 2021-179094 filed on Nov. 2, 2021, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND 
     The disclosure relates to a vehicle airbag apparatus. 
     A vehicle such as an automobile causes an airbag to be expanded and developed in front of an occupant upon a frontal contact with a contact object of the vehicle to thereby restrain, by the airbag, the upper body of the occupant that moves toward the front and to achieve a protection performance of the occupant accordingly. For example, Japanese Unexamined Patent Application Publication (JP-A) No. H03-159838 discloses an airbag apparatus that detects a build of an occupant on the basis of a factor such as a position of a seat, an inclination angle of a seat back, and a feeding amount of a seatbelt. The airbag apparatus disclosed in JP-A No. H03-159838 changes a timing at which an airbag is to be developed on the basis of the detected build of the occupant, thereby improving the protection performance of the occupant by the airbag. 
     SUMMARY 
     An aspect of the disclosure provides a vehicle airbag apparatus to be applied to a vehicle. The vehicle airbag apparatus includes an airbag, a front lid, and a tether. The airbag is configured to be disposed on a back side of an instrument panel of the vehicle. The airbag is configured to be expanded and developed between the instrument panel and a windshield glass of the vehicle in response to a supply of a gas such that the airbag is disposed on a front side in the vehicle and in front of an occupant of the vehicle. The front lid is configured to be disposed on the instrument panel. The front lid is configured to be ruptured and opened by the expanded and developed airbag such that the front li stands on the front side in the vehicle and at a front end of the airbag. The tether is disposed on an outer part of the airbag and couples the front lid and the airbag. The tether is configured to be elongated in a front-rear direction of the vehicle in a state where the airbag is expanded and developed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the specification, serve to explain the principles of the disclosure. 
         FIG.  1    is a left side diagram illustrating a left part positioned at the front of a cabin of a vehicle to which a vehicle airbag apparatus according to one example embodiment is applied, with an airbag being expanded and developed. 
         FIG.  2    is a plan diagram illustrating the vehicle airbag apparatus illustrated in  FIG.  1    as viewed from the above. 
         FIG.  3    is a side diagram illustrating a behavior of an airbag of an airbag apparatus according to a comparative example, when an expansion and a development of the airbag are completed. 
         FIG.  4    is a side diagram illustrating a state in which an occupant in a passenger seat who leans forward upon a frontal contact has come into contact with the airbag of the airbag apparatus according to the comparative example illustrated in  FIG.  3   . 
         FIG.  5    is a side diagram illustrating a state in which the occupant in the passenger seat who leans forward upon the frontal contact has come into contact with the airbag of the vehicle airbag apparatus according to one example embodiment. 
         FIG.  6    is a plan diagram illustrating a modification example of a tether of the vehicle airbag apparatus illustrated in  FIG.  2   . 
         FIG.  7    is a plan diagram illustrating another modification example of the tether of the vehicle airbag apparatus illustrated in  FIG.  2   . 
     
    
    
     DETAILED DESCRIPTION 
     For example, a size of an airbag may be increased from a viewpoint of protecting, by the airbag, any occupant from an occupant of a small build to an occupant of a large build. On the other hand, increasing a size of the airbag can allow the airbag to easily sway in a front-rear direction when an expansion and a development of the airbag are completed, and thereby can make a state in which the airbag is expanded and developed unstable. In addition, the unstableness upon the expansion and the development of the airbag can make it difficult to cause a reaction force of the airbag with respect to the occupant to sufficiently act when the occupant comes into contact with the airbag. In this case, a performance of absorbing a contact energy of the airbag with respect to the occupant can decrease. 
     It is desirable to provide a vehicle airbag apparatus that makes it possible to improve a contact energy absorbing performance of an airbag while stabilizing an expanded and developed state of the airbag. 
     In the following, a vehicle airbag apparatus 10 according to some example embodiments of the disclosure are described in detail with reference to the accompanying drawings. Note that the following description is directed to illustrative examples of the disclosure and not to be construed as limiting to the disclosure. Factors including, without limitation, numerical values, shapes, materials, components, positions of the components, and how the components are coupled to each other are illustrative only and not to be construed as limiting to the disclosure. Further, elements in the following example embodiments which are not recited in a most-generic independent claim of the disclosure are optional and may be provided on an as-needed basis. The drawings are schematic and are not intended to be drawn to scale. Throughout the present specification and the drawings, elements having substantially the same function and configuration are denoted with the same reference numerals to avoid any redundant description. In addition, elements that are not directly related to any embodiment of the disclosure are unillustrated in the drawings. 
     It should also be noted that an arrow UP, an arrow FR, and an arrow LH illustrated in the drawings on an as-necessary basis respectively indicate an upper side of a vehicle V, such as an automobile, to which the vehicle airbag apparatus  10  is applied, a front side of the vehicle V, and a left side, or one side in a vehicle-width direction, of the vehicle V. In the following description, the arrow UP, the arrow FR, and the arrow LH respectively indicate an up-down direction, a front-rear direction, and a right-left direction of the vehicle V when the description is given with reference to up and down directions, front and rear directions, and right and left directions, unless otherwise specified in particular. 
     Referring to  FIGS.  1  and  2   , the vehicle airbag apparatus  10  may be a passenger’s seat airbag apparatus that protects a passenger’s seat occupant PS as an occupant who is to sit on a passenger’s seat  50  disposed at a front part of a cabin of the vehicle V. It should be noted that  FIGS.  1  and  2    each illustrate a state in which an airbag  20  of the vehicle airbag apparatus  10  is expanded and developed. 
     The vehicle airbag apparatus  10  may include a module case  12 , the airbag  20 , and an inflator  30 . The airbag  20  may be stored inside the module case  12  in a folded state. The inflator  30  may eject a gas and supply the gas to the airbag  20 . In one embodiment, the inflator  30  may serve as a “gas generator”. The vehicle airbag apparatus  10  may also include a lid  14  and a pair of right and left tethers  40 . The lid  14  may be set on an instrument panel  52  of the vehicle V, and may cover the module case  12  from an upper side thereof. The tethers  40  may couple the lid  14  and the airbag  20  together. In the following, described is a configuration of the vehicle airbag apparatus  10  according to an example embodiment. 
     Module Case  12   
     The module case  12  may have a substantially rectangular box shape that is opened upwardly. The module case  12  may be disposed adjacent to a back side (i.e., a lower side) of the instrument panel  52 , and may be supported by a framework member of the instrument panel  52 , such as an unillustrated instrument panel reinforce. A center line CL in the right-left direction of the module case  12  may be disposed at a position that coincides with a center line in the right-left direction of the passenger’s seat occupant PS, as seen in a planar view from the upper side. 
     Lid  14   
     The lid  14  may be disposed at an upper side of the module case  12  of the instrument panel  52 , and may cover the module case  12  from the upper side thereof. The lid  14  may be configured to be ruptured and opened by the airbag  20  in response to an expansion and a development of the airbag  20 , and to open the module case  12  toward the upper side. For example, the lid  14  may include a front lid  14 F and a rear lid  14 R. The front lid  14 F may configure a front part of the lid  14 . The rear lid  14 R may configure a rear part of the lid  14 . The front lid  14 F and the rear lid  14 R each may have a substantially rectangular shape in which the vehicle-width direction corresponds to a longitudinal direction thereof. A center line in the right-left direction of the lid  14  may coincide with the center line CL of the module case  12 . 
     Upon the expansion and the development of the airbag  20 , the front lid  14 F may open toward the front with a front end of the front lid  14 F being a point of origin, and the rear lid  14 R may open toward the rear with a rear end of the rear lid  14 R being a point of origin. As described later in greater detail, the front lid  14 F may be opened at substantially 90 degrees from a state in which the module case  12  is closed and may be configured to be disposed in a standing fashion in a side view as seen in the vehicle-width direction, whereby a tip of the front lid  14 F may be disposed close to a lower side of a front end of a windshield glass  54 . The rear lid  14 R may be opened at substantially 180 degrees from the state in which the module case  12  is closed and may be configured to be interposed between the later-described airbag  20  and the instrument panel  52 , whereby the rear lid  14 R may be disposed adjacent to an upper side of the instrument panel  52 . A back surface (i.e., a lower surface) of the instrument panel  52  at an outer peripheral part of the lid  14  in which the lid  14  is set may have unillustrated notches that allow the front lid  14 F and the rear lid  14 R to open as a result of the rupture of the notches upon the expansion and the development of the airbag  20 . 
     Airbag  20   
     For example, the airbag  20  may have a bag shape in which outer peripheral parts of a plurality of base fabrics are sewn. The airbag  20  may be expanded and developed from an opening of the module case  12  toward the rear in response to the supply of the gas from the later-described inflator  30 , and may be configured to be disposed in front of the passenger’s seat occupant PS accordingly. In one example, a middle part in a width direction (in the right-left direction) of the airbag  20  may be configured to be positioned at the front of the passenger’s seat occupant PS to restrain, by the airbag  20 , the head H and the upper body of the passenger’s seat occupant PS that move toward the front upon a frontal contact. The airbag  20  may have a shape that is bilaterally symmetric with respect to the center line CL in a planar view. 
     A front part of the airbag  20  may be configured to be disposed along the instrument panel  52  and the windshield glass  54  of the vehicle V as seen in a side view, and come into contact with the instrument panel  52  and the windshield glass  54 . In addition, a front end of the airbag  20  may be configured to be disposed adjacent to a rear side of the front lid  14 F. With this configuration, the airbag  20  may be supported from a front side by the front lid  14 F, the instrument panel  52 , and the windshield glass  54 . It should be noted that a width (i.e., a size in the right-left direction) of the front lid  14 F is not particularly limited in an example embodiment. However, the width of the front lid  14 F may be changed on an as-necessary basis to secure a performance, by the front lid  14 F, of supporting the airbag  20 . 
     An upper end  20 A of the airbag  20  may be configured to be disposed at a rear side of the windshield glass  54  and at an upper side of the head H of the passenger’s seat occupant PS. A rear surface  20 B of the airbag  20  may be inclined to have a substantially curved shape toward the rear as the rear surface  20 B goes downward in a side view. In an example embodiment, the passenger’s seat occupant PS may be AM50 dummy, which is 50 percentile of U.S. adult males. 
     Inflator  30   
     The inflator  30  may be provided in the front end of the airbag  20 . The inflator  30  may have a hollow and substantially cylindrical shape in which the up-down direction corresponds to an axial direction, and may be fixed to a bottom wall of the module case  12 . The inflator  30   may be electrically coupled to an airbag ECU  32 . In one embodiment, the airbag ECU  32  may serve as a “processor”. Upon activation of the inflator  30  by the airbag ECU  32 , the gas ejected from an upper part of the inflator  30  may be supplied inside the airbag  20 , causing the airbag  20  to be expanded and developed. 
     The airbag ECU  32  may be electrically coupled to a contact sensor  34 . The airbag ECU  32  may detect or estimate the frontal contact with the vehicle V on the basis of data from the contact sensor  34 , and may cause the inflator  30  to activate in a case where the frontal contact is detected or estimated. 
     Tether  40   
     The pair of tethers  40  may be string-shaped members having flexibility and configured not to expand or contract. The pair of tethers  40  may couple the airbag  20  and the front lid  14 F together at an outer part of the airbag  20 , and may be disposed inside the module case  12  together with the airbag  20 . A length of the tether  40  may be so set that the tether  40  is in an elongated state in the front-rear direction upon completion of the expansion and the development of the airbag  20 . As used herein, the elongated state of the tether  40  may refer to a state in which a tensile force in a longitudinal direction is acted on the tether  40  and the tether  40  is thus strained tightly. 
     The tether  40  may have a front end  40 A that is coupled to a corner of the tip of the front lid  14 F, allowing the tether  40  to extend toward the rear from the front lid  14 F. In one embodiment, the front end  40 A may serve as “one end” or a “first end”. For example, the tether  40  may be configured to extend from the front lid  14 F obliquely upward toward the rear along the windshield glass  54  in a side view. The tether  40  may have a rear end  40 B that is coupled to an upper end part of the airbag  20 . In one embodiment, the rear end  40 B may serve as “the other end” or a “second end”. For example, the rear end  40 B of the tether  40  may be disposed at an upper side as compared with the front end  40 A of the tether  40  in the up-down direction. In one example, the rear end  40 B of the tether  40  may be configured to be disposed at an upper side of the head H of the passenger’s seat occupant PS and at a rear side as compared with the upper end  20 A of the airbag  20 . Accordingly, in one embodiment of the disclosure, the wording “the tether is configured to be elongated in the front-rear direction of the vehicle” may encompass an example case where the tether  40  is so elongated as to be disposed in a direction in which the tether  40  is inclined upwardly as the tether  40  goes to the rear. 
     The tether  40  may be configured to extend substantially in the front-rear direction and interposed between the airbag  20  and the windshield glass  54  in a planar view. For example, the tether  40  may be configured to be sightly inclined toward an outer side in the vehicle-width direction as the tether  40  goes toward the rear in a planar view. The rear end  40 B of the tether  40  may be configured to be disposed at an outer side in the vehicle-width direction of the head H of the passenger’s seat occupant PS in a planar view. In some embodiments, the tether  40  may be so disposed as to extend in the front-rear direction in a planar view. 
     Workings and Example Effects 
     A description is given next of workings and example effects of the vehicle airbag apparatus  10  according to an example embodiment. 
     In the vehicle airbag apparatus  10  according to an example embodiment described above, the airbag ECU  32  may activate the inflator  30  in a case where the airbag ECU  32  detects or estimates the frontal contact with the vehicle V on the basis of a signal supplied from the contact sensor  34 . Thus, the gas ejected from the inflator  30  may be supplied inside the airbag  20 . The airbag  20  having been supplied with the gas may rupture and open the front lid  14 F and the rear lid  14 R set on the instrument panel  52 , and may be expanded and developed from the opening of the module case  12  toward the rear. Hence, the airbag  20  may be expanded and developed at the front of the passenger’s seat occupant PS. 
     Upon the frontal contact of the vehicle V, the passenger’s seat occupant PS can move forward by an inertial force. For example, owing to attachment of a seatbelt S illustrated in  FIG.  1    to the passenger’s seat occupant PS, the upper body of the passenger’s seat occupant PS may be inclined to the front around the waist of the passenger’s seat occupant PS as the center. This helps to receive, by the rear surface  20 B of the airbag  20 , the head H and the upper body of the passenger’s seat occupant PS that move forward and thereby to restrain the head H and the upper body of the passenger’s seat occupant PS. 
     It should be noted that, in the vehicle airbag apparatus  10  according to an example embodiment, the front lid  14 F may be ruptured and opened toward the front and so stand as to be disposed adjacent to the front side of the front end of the airbag  20  upon the expansion and the development of the airbag  20 . In addition, the outer part of the airbag  20  may be provided with the pair of right and left tethers  40 , and the tethers  40  couple the front lid  14 F and the airbag  20  together. The tether  40  may be elongated in the front-rear direction in the state in which the airbag  20  is expanded and developed. This configuration helps to stabilize a state of the airbag  20  upon the completion of the expansion and the development of the airbag  20 , and to allow a sufficient reaction force to act on the passenger’s seat occupant PS from the airbag  20  upon receiving the upper body of the passenger’s seat occupant PS by the airbag  20 . 
     In the following, the workings and example effects according to an example embodiment described above are described while comparing them with those of an airbag apparatus according to a comparative example. The airbag apparatus according to the comparative example has a similar configuration to the vehicle airbag apparatus  10  according to an example embodiment, with the exception that, in the airbag apparatus according to the comparative example, the tethers  40  are eliminated from the vehicle airbag apparatus  10  according to an example embodiment as illustrated in  FIG.  3   . In other words, in the airbag apparatus according to the comparative example, the front lid  14 F is uncoupled to the airbag  20 , and configured to stand at the front of the airbag  20 . 
     The airbag  20  expands and develops from the module case  12  to the rear as a result of the supply of the gas of the inflator  30 . Thus, upon the completion of the expansion and the development of the airbag  20 , a rear part of the airbag  20  attempts, by an inertial force, to be displaced more on the rear side (i.e., on a side in an arrow A direction in  FIG.  3   ) than a regular position at which the expansion completes (i.e., a position of the airbag  20  indicated by a dashed-two dotted line in  FIG.  3   ). Hence, in the airbag apparatus according to the comparative example, the airbag  20  so deforms that the rear surface  20 B of the airbag  20  approaches the passenger’s seat occupant PS upon the completion of the expansion and the development of the airbag  20  (see the airbag  20  illustrated by a solid line in  FIG.  3   ), which can allow the airbag  20   to sway in the front-rear direction upon the completion of the expansion and the development of the airbag  20 . It should be appreciated that the phenomenon that the airbag  20  sways tend to occur easily in a case where a size of the airbag  20  is increased. Accordingly, in the airbag apparatus according to the comparative example, the state in which the airbag  20  is expanded and developed can become unstable. 
     In addition, referring to  FIG.  4   , the head H and the upper body of the passenger’s seat occupant PS move to the front and enter the rear surface  20 B of the airbag  20  (see an arrow B in  FIG.  4   ) upon receiving the head H and the upper body of the passenger’s seat occupant PS by the airbag  20 , causing an internal pressure of the airbag  20  to be increased (see an arrow P of  FIG.  4   ). Hence, in the airbag apparatus according to the comparative example, the front end of the airbag  20  can press the front lid  14 F toward the front by the increase in the internal pressure of the airbag  20 , which can cause the front lid  14 F to tilt forward (see the front lid  14 F and the airbag  20  indicated by a solid line in  FIG.  4   ). In this case, the front end of the airbag  20  is displaced toward the front and enters a region between the front end of the windshield glass  54  and the front end of the front lid  14 F. Accordingly, the front end of the airbag  20  can escape toward the front, which can cause a decrease in the reaction force that acts on the passenger’s seat occupant PS from the airbag  20  and can thereby decrease a performance of absorbing a contact energy of the airbag  20  with respect to the passenger’s seat occupant PS. 
     In contrast, in the vehicle airbag apparatus  10  according to an example embodiment, the pair of right and left tethers  40  may be provided at the outer part of the airbag  20  and may couple the airbag  20  and the front lid  14 F together. In addition, the tether  40  may be elongated in the front-rear direction in the state in which the airbag  20  is expanded and developed. Thus, the airbag  20  and the lid  14  may be coupled together by the tether  40  stretched in the longitudinal direction. Hence, it helps to suppress, by the tether  40 , the rear end of the airbag  20  from being displaced more on the rear side than the regular position at which the expansion completes, even when the inertial force is acted on the airbag  20  upon the completion of the expansion and the development of the airbag  20 . Accordingly, it helps to suppress the airbag  20  from swaying in the front-rear direction after the completion of the expansion and the development of the airbag  20  and to stabilize the state in which the airbag  20  is expanded and developed. 
     Further, referring to  FIG.  5   , the internal pressure of the airbag  20  increases and the front end of the airbag  20  may press the front lid  14 F toward the front similarly to the above-described manner upon receiving, by the airbag  20 , the head H and the upper body of the passenger’s seat occupant PS. It should be noted that the airbag  20  and the lid  14  may be coupled together by the tether  40  elongated in the front-rear direction as described above. Thus, it helps to suppress, by the tether  40 , the front lid  14 F from tilting to the front even when the front end of the airbag  20  presses the front lid  14 F toward the front. For example, the tether  40  helps to favorably keeps the state in which the frond lid  14 F stands and to favorably keep the state in which the front lid  14 F supports the front end of the airbag  20 . Hence, it helps to allow the sufficient reaction force to act on the passenger’s seat occupant PS from the airbag  20 . Accordingly, it helps to improve the contact energy absorbing performance of the airbag  20  with respect to the passenger’s seat occupant PS. The vehicle airbag apparatus  10  according to an example embodiment described above helps to improve the contact energy absorbing performance of the airbag  20  with respect to the passenger’s seat occupant PS while stabilizing the state in which the expansion and the development of the airbag  20  are completed. 
     In some embodiments, the elongated tether  40  may be configured to be interposed between the airbag  20  and the windshield glass  54 . Thus, the airbag  20  may press the tether  40  toward the windshield glass  54  in response to the increase in the internal pressure of the airbag  20  upon the entry of the head H and the upper body of the passenger’s seat occupant PS onto the airbag  20 . Accordingly, it helps to favorably keep the state in which the tether  40  is elongated and to favorably keep the state in which the front lid  14 F stands. 
     In some embodiments, the rear end  40 B of the tether  40  may be configured to be positioned more on the upper side than the head H of the passenger’s seat occupant PS. Thus, it helps to suppress the tether  40  from interfering with the passenger’s seat occupant PS when the head H and the upper body of the passenger’s seat occupant PS, inclined to the front, have entered the rear surface  20 B of the airbag  20  from the rear. For example, it helps to suppress a rear end part of the tether  40  from interfering with the passenger’s seat occupant PS. 
     In some embodiments, the rear end  40 B of the tether  40  may be configured to be disposed more on the rear than the upper end  20 A of the airbag  20 . Thus, it helps to allow the rear end  40 B of the tether  40  to be disposed closer to the rear surface  20 B of the airbag  20 . Hence, it helps to allow the rear end  40 B of the tether  40  to be drawn toward the passenger’s seat occupant PS when the head H and he upper body of the passenger’s seat occupant PS, inclined to the front, have entered the airbag  20  from the rear surface  20 B. Accordingly, it helps to allow the airbag  20  to pull the rear end  40 B of the tether  40  toward the rear (i.e., on the other side in the longitudinal direction and in a direction of an arrow F in  FIG.  5   ). This in turn helps to more effectively keep the state in which the front lid  14 F stands. 
     In some embodiments, the rear end  40 B of the tether  40  may be configured to be disposed on the outer side in the vehicle-width direction of the head H of the passenger’s seat occupant PS in a planar view. Thus, it helps to suppress the tether  40  from interfering with the passenger’s seat occupant PS when the head H and the upper body of the passenger’s seat occupant PS, inclined to the front, have entered the rear surface  20 B of the airbag  20  from the rear. For example, it helps to suppress the rear end part of the tether  40  from interfering with the passenger’s seat occupant PS. 
     In some embodiments, the front end  40 A of the tether  40  may be coupled to the corner of the tip of the front lid  14 F. Thus, it helps to support the tip of the stood front lid  14 F by the tether  40 . Hence, it helps to stably support the stood front lid  14 F as compared with an example case where a middle part in the up-down direction of the stood front lid  14 F is supported by the tether  40 . 
     In some embodiments, the pair of tethers  40  may be configured to extend from the corners of the tip of the front lid  14 F toward the rear and the rear ends of the respective tethers  40  may be coupled to the airbag  20 . Thus, it helps to couple the airbag  20  and the front lid  14 F together by the pair of tethers  40  on both sides in the right-left direction with respect to the middle part in the right-left direction of the front lid  14 F. Hence, it helps to couple the airbag  20  and the front lid  14 F together with good balance in the right-left direction upon the expansion and the development of the airbag  20 . 
     In some embodiments, the lid  14  may include the front lid  14 F that configures the front part of the lid  14  and the rear lid  14 R that configures the rear part of the lid  14 . The front lid  14 F and the rear lid  14 R may be configured to be ruptured and opened to the front and the rear upon the expansion and the development of the airbag  20 . Further, the rear lid  14 R may be configured to be interposed between the airbag  20  and the instrument panel  52 . Thus, it helps to press the rear lid  14 R downward by the airbag  20  in a case where the head H and the upper body of the passenger’s seat occupant PS are received by the airbag  20  and the internal pressure of the airbag  20  is thereby increased, which in turn helps to ensure that the rear lid  14 R comes into contact with the instrument panel  52 . This means that it helps to suppress a gap from being formed between the rear lid  14 R and the instrument panel  52  upon restraining the passenger’s seat occupant PS by the airbag  20 . Hence, it helps to achieve stabilization of the reaction force that acts on the passenger’s seat occupant PS upon restraining the passenger’s seat occupant PS by the airbag  20 . 
     In an example embodiment described above, the rear end  40 B of the tether  40  may be configured to be disposed more on the rear side than the upper end  20 A of the airbag  20  and at the upper side of the head H of the passenger’s seat occupant PS. However, a position of the rear end  40 B of the tether  40  is optional and may be variously modified. In some embodiments, the rear end  40 B of the tether  40  may be configured to be disposed more on the front side than the upper end  20 A of the airbag  20  and at the upper side of the head H of the passenger’s seat occupant PS. Even in this example, it helps to suppress the tether  40  from interfering with the passenger’s seat occupant PS when the head H and the upper body of the passenger’s seat occupant PS, inclined to the front, have entered the airbag  20  from the rear. In some embodiments, the rear end  40 B of the tether  40  may be configured to be disposed more on the front side than the upper end  20 A of the airbag  20  and at a lower side of the head H of the passenger’s seat occupant PS. Even in this example, it helps to press the tether  40  toward the windshield glass  54  by the airbag  20  in a case where the head H and the upper body of the passenger’s seat occupant PS are received by the airbag  20  and the internal pressure of the airbag  20  is thereby increased, which in turn helps to favorably keep the elongated state of the tether  40 . 
     In an example embodiment described above, the tether  40  may be configured to extend linearly toward the rear from the tip corner of the front lid  14 F in a planar view. However, an extending direction of the tether  40  is not limited thereto. In some embodiments, referring to  FIG.  6   , the tether  40  may be configured to extend toward the rear along a side surface of the airbag  20  from the tip corner of the front lid  14 F. Thus, it helps to suppress, with good balance, the displacement toward the rear of the airbag  20  by the pair of right and left tethers  40  upon the completion of the expansion and the development of the airbag  20 . Further, in this example, the rear end  40 B of the tether  40  may be configured to be disposed at an outer peripheral part of the rear surface  20 B of the airbag  20 . Thus, it helps to draw the rear ends  40 B of the respective tethers  40  toward a middle in a width direction of the airbag  20  to thereby allow the front lid  14 F to be pulled toward both sides in a width direction of the front lid  14 F by the tethers  40 , when the head H and the upper body of the passenger’s seat occupant PS, inclined to the front, have entered the airbag  20  from the rear. 
     In an example embodiment described above, the pair of right and left tethers  40  may couple the front lid  14 F and the airbag  20  together. The number of tethers  40  that couple the front lid  14 F and the airbag  20  together is optional and may be set to any number. In some embodiments, the number of tethers  40  may be three, and the additional tether  40  may couple the middle part in the right-left direction of the tip of the front lid  14 F and the upper end of the airbag  20 . 
     In an example embodiment described above, the front end  40 A of the tether  40  may be coupled to the corner of the tip of the front lid  14 F. In some embodiments, the front end  40 A of the tether  40  may be coupled to the middle part in the up-down direction of the stood front lid  14 F. 
     In an example embodiment described above, the tether  40  may be the string-shaped member having the flexibility and configured not to expand or contract. However, the characteristics of the tether  40  are not limited thereto. In some embodiments, the tether  40  may be a band-shaped member having flexibility and configured to expand or contract. In this example, referring to  FIG.  7   , a width of the rear end  40 B of the tether  40  may be set to be greater than a width of the front end  40 A of the tether  40  in a manner corresponding to a width of the airbag  20 . Further in this example, although unillustrated, the rear end part of the tether  40  may be branched in the width direction to couple the rear ends  40 B of the respective tethers  40  to the airbag  20 . 
     In an example embodiment described above, the lid  14  may include the front lid  14 F and the rear lid  14 R. In some embodiments, the lid  14  may include only the front lid  14 F. In this example, the lid  14  may be configured to be ruptured and opened only toward the front. 
     As used herein, the term “collision” may be used interchangeably with the term “contact”. 
     Although some example embodiments of the disclosure have been described in the foregoing by way of example with reference to the accompanying drawings, the disclosure is by no means limited to the embodiments described above. It should be appreciated that modifications and alterations may be made by persons skilled in the art without departing from the scope as defined by the appended claims. The disclosure is intended to include such modifications and alterations in so far as they fall within the scope of the appended claims or the equivalents thereof.