Patent Publication Number: US-2019176117-A1

Title: Webbing take-up device and method of manufacturing thereof

Description:
TECHNICAL FIELD 
     The present invention relates to a webbing take-up device and a method of manufacturing thereof. 
     BACKGROUND ART 
     A webbing take-up device that has a spool, at which a webbing that is worn by a vehicle occupant is taken up, and a pretensioner, which eliminates slack of the webbing at the time of an emergency of the vehicle, is disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2012-35748. Further, the pretensioner is configured to include a gas generator that generates gas when operated, a pipe to whose interior the gas generated by the gas generator is supplied, and a driving force transmitting member that is disposed within the pipe. Further, due to gas that is generated by the gas generator being supplied into the pipe and the driving force transmitting member being moved, the spool can be rotated in the take-up direction. 
     By the way, a wire that is provided at the vehicle side is connected to the gas generator. Therefore, at the time of mounting the gas generator to the pipe, it is desirable that displacement of the gas generator with respect to the pipe be restricted. Thus, in the webbing take-up device described in JP-A No. 2012-35748, displacement of the gas generator with respect to the pipe is restricted due to a portion of the gas generator being press-fit into the pipe while being deformed by a pair of projections that are provided at the pipe. 
     SUMMARY OF INVENTION 
     Technical Problem 
     In view of the above-described circumstances, an object of the present invention is to provide a webbing take-up device that can restrict displacement of a gas generating device with respect to a gas generating device mounting portion, and a method of manufacturing the webbing take-up device. 
     Solution to Problem 
     A webbing take-up device of a first aspect of the present disclosure comprises: a spool at which a webbing, which is worn by a vehicle occupant, is taken up by the spool being rotated in a take-up direction; and a pretensioner mechanism that has a gas generating device that is configured to generate gas when operated, and a gas generating device mounting portion, that is formed in a shape of a tube into which the gas generating device is inserted and that is provided with a recessed portion that is open toward a side of the gas generating device and a convex portion that is formed along the recessed portion and is convexly-shaped toward the side of the gas generating device and at which a portion of the gas generating device is anchored, the pretensioner mechanism rotating the spool in the take-up direction owing to the gas generating device being operated at a time of an emergency of a vehicle. 
     A method of manufacturing a webbing take-up device of a second aspect of the present disclosure is applied to the manufacturing of the webbing take-up device of the first aspect. This method of manufacturing a webbing take-up device comprises: using a die that supports a pipe formed in a tube shape, a first punch that is formed in a shape corresponding to an external shape of the gas generating device, and a second punch having a portion formed in a shape corresponding to the recessed portion; forming a portion of the pipe into which the gas generating device can be inserted, by setting the pipe at the die and nipping the pipe between the die and the first punch; forming the gas generating device mounting portion of the pipe, which has the recessed portion and the convex portion, by inserting the second punch into the portion of the pipe into which the gas generating device can be inserted; and fixing the gas generating device to the gas generating device mounting portion by inserting the gas generating device into the gas generating device mounting portion. 
     Advantageous Effects of Invention 
     In accordance with the webbing take-up device of the first aspect of the present disclosure, when the gas generating device is operated, the spool is rotated in the take-up direction, and the webbing is taken up by the spool. Here, in the invention of claim  1 , recessed portions and convex portions are formed at the gas generating device mounting portion at which the gas generating device is mounted. The recessed portions are open toward a side of the gas generating device. The convex portions, which are convexly-shaped toward the side of the gas generating device, are formed along the recessed portions. Further, due to a portion of the gas generating device being anchored on the convex portions, displacement of the gas generating device with respect to the gas generating device mounting portion can be restricted. 
     In accordance with the method of manufacturing a webbing take-up device of the second aspect of the present disclosure, first, the pipe is set at the die, and the pipe is nipped-in between the die and the first punch. Due thereto, a portion into which the gas generating device can be inserted is formed in the pipe. Next, the second punch is inserted into the portion of the pipe, into which the gas generating device can be inserted. Due thereto, the recessed portions are formed at portions of the pipe, that are pushed by the second punch, and the convex portions are formed along these recessed portions. Namely, the gas generating device mounting portion, which has the recessed portions and the convex portions, is formed at the pipe. Next, the gas generating device is inserted into the gas generating device mounting portion, and the gas generating device is fixed to the gas generating device mounting portion. Here, in the state in which the gas generating device is inserted into the gas generating device mounting portion, displacement of the gas generating device with respect to the gas generating device mounting portion can be restricted by the convex portions that are formed at the gas generating device mounting portion. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a front view showing a webbing take-up device. 
         FIG. 2  is a cross-sectional view showing the cross-section of a pretensioner mechanism cut along line  2 - 2  shown in  FIG. 1 . 
         FIG. 3 ( 1 ) is a cross-sectional view showing the cross-section of a gas generating device mounting portion, and  FIG. 3 ( 2 ) is a cross-sectional view showing the cross-section of the gas generating device mounting portion cut along line  3 B- 3 B shown in  FIG. 3 ( 1 ). 
         FIGS. 4 ( 1 ) through  4 ( 4 ) are explanatory drawings for explaining steps of forming the gas generating device mounting portion at a pipe. 
         FIGS. 5 ( 1 ) and  5 ( 2 ) are cross-sectional views that correspond to  FIGS. 3 ( 1 ) and  3 ( 2 ) and that show the gas generating device mounting portion having recessed portions and convex portions formed by a triangular punch. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A webbing take-up device relating to an embodiment of the present invention is described by using  FIG. 1  through  FIG. 3 . Note that the arrow Z direction, the arrow R direction and the arrow C direction that are shown appropriately in the drawings indicate the rotation axial direction, the rotation radial direction and the rotation peripheral direction of a spool, respectively. Hereinafter, when merely axial direction, radial direction and peripheral direction are used, they refer to the rotation axial direction, the rotation radial direction and the rotation peripheral direction of the spool, unless otherwise indicated. 
     As shown in  FIG. 1 , a webbing take-up device  10  of the present embodiment has a spool  14 , at which a webbing  12 , which is worn by a vehicle occupant, is taken up and that is rotated in a pull-out direction due to the webbing  12  being pulled-out, and a frame  16  that rotatably supports the spool  14 . Further, the webbing take-up device  10  has a locking mechanism  18  that restricts rotation of the spool  14  in the pull-out direction at the time of an emergency of the vehicle (at a time of sudden pulling-out of the webbing  12  from the spool  14 , or at a time of rapid deceleration of the vehicle, at a time of a collision of the vehicle or the like), and a pretensioner mechanism  20  that forcibly rotates the spool  14  in a take-up direction at the time of an emergency of the vehicle. 
     The spool  14  has a take-up portion  14 A that is formed substantially in a cylindrical shape. The webbing  12 , which is shaped as an elongated strip, is taken up onto the take-up portion  14 A from the proximal end side of the webbing  12 . The webbing  12  extends out from the frame  16  toward the upper side, and can be worn by a vehicle occupant who is seated in a seat (not illustrated) of the vehicle. Further, owing to the spool  14  being rotated toward a peripheral direction other side in the take-up direction (the opposite direction to the direction of arrow C), the webbing  12  is taken up onto the spool  14 , and, due to the webbing  12  being pulled-out from the spool  14 , the spool  14  is rotated toward a peripheral direction one side (in the arrow C direction), i.e., the spool  14  is rotated in the pull-out direction. 
     The locking mechanism  18 , which restricts rotation of the spool  14  in the pull-out direction at the time of an emergency of the vehicle, is provided at an axial direction another side (the side opposite to the arrow Z direction) of the spool  14 . Further, the pretensioner mechanism  20 , which eliminates slack in the webbing  12  that is worn by the vehicle occupant by forcibly rotating the spool  14  in the take-up direction at the time of an emergency of the vehicle, is provided at an axial direction one side (the arrow Z direction side) of the spool  14 . 
     As shown in  FIG. 2 , the pretensioner mechanism  20  of the present embodiment is a rack-and-pinion type pretensioner mechanism. This pretensioner mechanism  20  is configured to include a pinion  22  that is provided so as to be able to rotate integrally with the spool  14  at the axial direction one side portion of the spool  14 , a piston  26  that has a rack  24  that meshes-together with the pinion  22 , a micro-gas generator  42  (see  FIG. 3 ) that serves as a gas generating device and generates high-pressure gas instantaneously when operated, and a pipe  40  that accommodates the piston  26  therein and that has a micro-gas generator mounting portion  40 A to which the micro-gas generator  42  is mounted. 
     An O-ring  32  is fit-together with the lower portion of the piston  26 . The O-ring  32  is fit tightly to the inner wall of the pipe  40 . Due thereto, the gas of the micro-gas generator  42  that has been supplied into the pipe  40  is prevented from coming-out upwardly (toward the pinion  22  side) from the gap between the piston  26  and the pipe  40 . 
     As shown in  FIGS. 3 ( 1 ) and  3 ( 2 ), the micro-gas generator  42  has a gas generating agent accommodating portion  42 A that is formed in a cylindrical shape having a bottom and in which a gas generating agent is filled, and an ignition device accommodating portion  42 B that is formed in a cylindrical shape and has an ignition device that generates heat when energized. Further, due to the igniting device generating heat, the gas generating agent is ignited, and, due to the gas generating agent that is filled within the gas generating agent accommodating portion  42 A combusting, high-pressure gas is generated instantaneously. Further, due to the pressure of the gas that is generated within the gas generating agent accommodating portion  42 A, the gas generating agent accommodating portion  42 A is expanded and deformed, and thereafter, breaks, and the high-temperature, high-pressure gas that flows-out from the gas generating agent accommodating portion  42 A is supplied to the pipe  40  interior. 
     The structure of the micro-gas generator mounting portion  40 A, which serves as the gas generating device mounting portion and is an important portion of the present embodiment, is described next. 
     As shown in  FIGS. 3 ( 1 ) and  3 ( 2 ), the micro-gas generator mounting portion  40 A has a first tubular portion  40 A 1 , the majority of which is formed in a cylindrical shape having an inner diameter D 2  that is larger than outer diameter D 1  of the ignition device accommodating portion  42 B of the micro-gas generator  42 . Further, the micro-gas generator mounting portion  40 A has a second tubular portion  40 A 2  that is disposed coaxially with the first tubular portion  40 A 1 , and that is formed in a cylindrical shape having an inner diameter D 4  that is smaller than the inner diameter D 2  of the first tubular portion  40 A 1  and is larger than outer diameter D 3  of the gas generating agent accommodating portion  42 A of the micro-gas generator  42 . 
     A pair of recessed portions  54  is formed in the inner peripheral portion of the first tubular portion  40 A 1  (the portion at the side at which the ignition device accommodating portion  42 B of the micro-gas generator  42  is disposed). The pair of recessed portions  54  is disposed at a uniform interval along the peripheral direction of the first tubular portion  40 A 1 . The recessed portions  54  are formed by the inner peripheral portion of the first tubular portion  40 A 1  being pushed by a convex/concave portion forming punch  70  (see  FIG. 4 ( 4 )) that is described later. Further, convex portions  56 , which are convexly-shaped toward the side at which the ignition device accommodating portion  42 B of the micro-gas generator  42  is disposed, are respectively formed at the both sides (the both sides in the peripheral direction of the first tubular portion  40 A 1 ) of the portions, where the recessed portions  54  are formed, of the inner peripheral portion of the first tubular portion  40 A 1 . Inner diameter D 5  of an imaginary circle C, which passes-through distal ends  56 A in the projecting-out direction of the convex portions  56 , is an inner diameter that is small as compared with the inner diameter D 2  of the region, where the recessed portions  54  and the convex portions  56  are not formed, of the first tubular portion  40 A 1 . In addition, the inner diameter D 5  of this imaginary circle C is an inner diameter that is smaller than the outer diameter D 1  of the ignition device accommodating portion  42 B of the micro-gas generator  42 . 
     The structure that forms the micro-gas generator mounting portion  40 A is described next by using  FIGS. 4 ( 1 ) through  4 ( 4 ). 
     The micro-gas generator mounting portion  40 A is formed by using a press device  72  that is configured to include a thickness-increasing die  58 , a first pipe-expanding die  60  and a second pipe-expanding die  62  that serve as a die and support the pipe  40  that is formed in the cylindrical shape, a thickness-increasing punch  64 , a first pipe-expanding punch  66  and a second pipe-expanding punch  68  that serve as a first punch, and the convex/concave portion forming punch  70  that serves as a second punch. 
     As shown in  FIG. 4 ( 1 ), the thickness-increasing die  58  and the thickness-increasing punch  64  are for forming the wall-thickness of the end portion, at the one side of the pipe  40  of the material, to a predetermined thickness. The clearance between the thickness-increasing die  58  and the thickness-increasing punch  64  is set to a clearance that corresponds to the aforementioned predetermined thickness. 
     As shown in  FIGS. 4 ( 2 ) and  4 ( 3 ), the first pipe-expanding die  60  and the first pipe-expanding punch  66 , and the second pipe-expanding die  62  and the second pipe-expanding punch  68 , are used in order to make the end portion, which is at the one side of the pipe  40  and has been formed to a predetermined thickness by the thickness-increasing die  58  and the thickness-increasing punch  64 , approach a shape that corresponds to the external shape of the micro-gas generator  42 , in two stages. Note that, at the second pipe-expanding punch  68 , outer diameter D 7  of a portion  68 A that forms the first tubular portion  40 A 1  is formed in a cylindrical shape having an outer diameter that is substantially equal to the outer diameter of the ignition device accommodating portion  42 B (see  FIG. 1 ) of the micro-gas generator  42 , and, at the second pipe-expanding punch  68 , outer diameter D 8  of a portion  68 B that forms the second tubular portion  40 A 2  is formed in a cylindrical shape having an outer diameter that is substantially equal to the outer diameter D 3  (see  FIG. 3 ) of the gas generating agent accommodating portion  42 A of the micro-gas generator  42 . Due thereto, after the pressing step by the second pipe-expanding die  62  and the second pipe-expanding punch  68  has been carried out, the micro-gas generator  42  can be rotatingly displaced within the end portion at the one side of the pipe  40 , in a state in which the micro-gas generator  42  is inserted in the end portion at the one side of the pipe  40 . 
     As shown in  FIG. 4 ( 4 ), the convex/concave portion forming punch  70  is formed in the shape of a block that has corner portions  70 A that are formed in shapes (shapes that fit-together with the two recessed portions  54 ) corresponding to the two recessed portions  54  (see  FIG. 2 ) that are formed at the micro-gas generator mounting portion  40 A. 
     Using the above-described press device  72 , first, as shown in  FIG. 4 ( 1 ), the pipe  40  is set at the thickness-increasing die  58 , and the thickness is increased while the end portion at the one side of the pipe  40  is nipped-in between the thickness-increasing die  58  and the thickness-increasing punch  64  (thickness-increasing step). Due thereto, the wall thickness, of the end portion of the one side of the pipe  40 , of the material is formed to a predetermined thickness. 
     Next, as shown in  FIGS. 4 ( 2 ) and  4 ( 3 ), the end portion at the one side of the pipe  40  is nipped-in between the first pipe-expanding die  60  and the first pipe-expanding punch  66 , and, thereafter, the end portion at the one side of the pipe  40  is nipped-in between the second pipe-expanding die  62  and the second pipe-expanding punch  68 . Due thereto, the end portion at the one side of the pipe  40  is gradually made to approach a shape that corresponds to the external shape of the micro-gas generator  42  (a first pipe-expanding and second pipe-expanding step that serves as a first step). 
     Next, as shown in  FIG. 4 ( 4 ), due to the convex/concave portion forming punch  70  being inserted in the end portion of the one side of the pipe  40  that is in a state of being set in the second pipe-expanding die  62 , the micro-gas generator mounting portion  40 A that has the recessed portions  54  and the convex portions  56  is formed (convex/concave portion forming step that serves as a second step). 
     Then, finally, the micro-gas generator  42  is inserted in the micro-gas generator mounting portion  40 A, and the axial direction proximal end portion of the micro-gas generator mounting portion  40 A is caulked to the radial direction inner side. Due thereto, the micro-gas generator  42  is fixed to the micro-gas generator mounting portion  40 A (micro-gas generator fixing step that serves as a third step). 
     Through the above-described steps, the micro-gas generator mounting portion  40 A of the pipe  40  that structures a portion of the webbing take-up device  10  of the present embodiment is formed, and the micro-gas generator  42  is fixed to the micro-gas generator mounting portion  40 A. Further, due to the respective structural parts, such as the pipe  40  to which the micro-gas generator  42  is fixed, and the like, being assembled together, the webbing take-up device  10  of the present embodiment is manufactured. 
     Operation and Effects of Present Embodiment 
     Operation and effects of the present embodiment are described next. 
     As shown in  FIG. 1 , in the present embodiment, the webbing  12  is worn by the body of an occupant of the vehicle due to the webbing  12  being pulled-out from the spool  14 . 
     Further, in the state in which the webbing  12  is worn by the body of the occupant of the vehicle, when the locking mechanism  18  operates at the time of an emergency of the vehicle, rotation of the spool  14  in the pull-out direction is limited. As a result, pulling-out of the webbing  12  from the spool  14  is limited, and the body of the vehicle occupant, which starts to move toward the vehicle front side, is restrained by the webbing  12 . 
     Further, as shown in  FIG. 3 , when the gas that is generated by the micro-gas generator  42  is supplied into the second tubular portion  42  of the cylinder  30  due to the micro-gas generator  42  being operated at the time of an emergency of the vehicle, as shown in  FIG. 2 , the piston  26  is moved toward the upper side. Then, the rack  24  of the piston  26  that has moved meshes-together with the pinion  22 , and the pinion  22  is rotated in the take-up direction. Due thereto, the spool  14  is rotated in the take-up direction by a predetermined number of rotations, and a predetermined length of the webbing  12  is taken-up onto the spool  14 . As a result, slack of the webbing  12  that is worn by the vehicle occupant is eliminated, and the restraining force of the vehicle occupant by the webbing  12  is increased. 
     Here, as shown in  FIGS. 3 ( 1 ) and  3 ( 2 ), in the present embodiment, the recessed portions  54  whose micro-gas generator  42  sides are open, are formed at the micro-gas generator mounting portion  40 A at which the micro-gas generator  42  is mounted, and the convex portions  56  that are formed in shapes that are convex toward the micro-gas generator  42  side are formed along the recessed portions  54 . Further, due to the ignition device accommodating portion  42 B of the micro-gas generator  42  anchoring on the convex portions  56 , rotational displacement of the micro-gas generator  42  with respect to the micro-gas generator mounting portion  40 A is restricted. Due thereto, in the present embodiment, displacement of the micro-gas generator  42  with respect to the micro-gas generator mounting portion  40 A can be restricted. As a result, the connector of a wire that is provided at the vehicle can be mounted to the micro-gas generator  42  in a predetermined attitude. 
     Further, in the present embodiment, the convex portions  56 , on which the ignition device accommodating portion  42 A of the micro-gas generator  42  is anchored, can be formed easily by inserting the convex/concave portion forming punch  70  into the end portion at the one side of the pipe  40 . This point can devise simplification of and shortening of time of the manufacturing processes, as compared with a case in which a step for forming a portion, on which the ignition device accommodating portion  42 B of the micro-gas generator  42  is anchored, is provided separately after the step of machining by the press device  72  has been carried out. Further, in the present embodiment, by structuring the respective punches (the thickness-expanding punch  64 , the first pipe-expanding punch  66 , the second pipe-expanding punch  68  and the convex/concave portion forming punch  70 ) to move in the same direction, the pipe  40  which is the work piece can be conveyed easily, and the cycle time can be shortened, and machining can be carried out at the same equipment. 
     Note that the present embodiment describes a structure in which, by forming the two recessed portions  54 , the convex portions  56  are formed respectively at the both side portions of the two recessed portions  54 . However, the present invention is not limited to this. For example, as shown in  FIGS. 5 ( 1 ) and  5 ( 2 ), there can be a structure in which, by using a triangular punch  74  that serves as the second punch and that is formed in a triangular cross-section, three of the recessed portions  54  are formed, and the convex portions  56  are formed respectively at the both side portions of these three recessed portions  54 . Further, the recessed portions  54  and the convex portions  56  may be formed at only a portion in the axial direction of the first tubular portion  40 A 1 . 
     Although an embodiment of the present invention has been described above, the present invention is not limited to the above, and can of course be implemented by being modified in various ways other than the above within a scope that does not depart from the gist thereof. 
     The disclosure of Japanese Patent Application No. 2016-122764 that was filed on Jun. 21, 2016, is incorporated in its entirety by reference into the present specification.