Patent Publication Number: US-2020298793-A1

Title: Pretensioner, retractor, and seat belt device

Description:
TECHNICAL FIELD 
     The present invention relates to a pretensioner, a retractor, and a seat belt device, and more particularly to a pretensioner, a retractor, and a seat belt device suitable for a configuration including a rod-shaped power transmission member. 
     BACKGROUND ART 
     Generally, a vehicle such as an automobile is provided with a seat belt device which restrains an occupant on a seat including a seat portion on which the occupant sits and a backrest portion located on the back of the occupant. Such a seat belt device includes a webbing for restraining an occupant, a retractor for winding the webbing, a buckle disposed on a side surface of the seat, and a tongue disposed on the webbing, and by fitting the tongue to the buckle, the occupant is restrained to the seat by the webbing. Also, it has become common for the retractor to have a pretensioner for removing slack in the webbing in an emergency such as a vehicle collision (for example, see Patent Literature 1). 
     The pretensioner described in Patent Literature 1 includes a ring gear ( 24 ) arranged in a spool ( 14 ) for winding webbing and a power transmission means ( 16 ) for transmitting power to the ring gear ( 24 ) in an emergency. The power transmission means ( 16 ) includes a rod-shaped power transmission member ( 22 ) which transmits power to the ring gear ( 24 ) while plastically deforming, a pipe ( 20 ) accommodating the power transmission member ( 22 ), and a gas generator ( 18 ) located at the end portion of the pipe ( 20 ). 
     CITATION LIST 
     Patent Literature 
     [Patent Literature 1]: International Publication No. 2012/143090 
     SUMMARY OF INVENTION 
     Technical Problem 
     The pretensioner employing the rod-shaped power transmission member as described in Patent Literature 1 has the highest load when the power transmission member first collides with the ring gear in an initial driving stage. Therefore, the power transmission member needs a predetermined thickness (strength). On the other hand, when the entire rod member is made thicker, the number of engagement teeth of the ring gear with respect to the power transmission member increases with the transition to a steady drive stage. Thus, the resistance when the power transmission member slides inside the pipe will increase. 
     The invention has been made in view of such a problem and an object thereof is to provide a pretensioner, a retractor, and a seat belt device which can achieve both securing of the strength of a power transmission member in an initial driving stage and reduction of the sliding resistance against the power transmission member in a steady driving stage. 
     Solution to Problem 
     According to an aspect of the invention, there is provided a pretensioner which includes a ring gear connected to a spool which winds webbing to restrain an occupant and a power transmission device which transmits power to the ring gear in an emergency, in which the power transmission device includes a rod-shaped power transmission member which transmits power to the ring gear while plastically deforming and a tip end of the power transmission member has an enlarged portion formed thicker than other portions of the power transmission member, and further the enlarged portion is made of the same material as the power transmission member. 
     According to another aspect of the invention, there is provided a retractor which includes a spool which winds webbing for restraining an occupant and a pretensioner which winds the webbing to remove slack in an emergency, where the pretensioner includes a ring gear connected to the spool and a power transmission device which transmits power to the ring gear in an emergency and the power transmission device includes a rod-shaped power transmission member which transmits power to the ring gear while plastically deforming, and further a tip end of the power transmission member has an enlarged portion formed thicker than other portions of the power transmission member, and still further the enlarged portion is made of the same material as the power transmission member. 
     According to still another aspect of the invention there is provided a seat belt device which includes webbing for restraining an occupant and a retractor for winding the webbing, where the retractor includes a ring gear connected to the spool and a power transmission device which transmits power to the ring gear in an emergency and the power transmission device includes a rod-shaped power transmission member which transmits power to the ring gear while plastically deforming, and further a tip end of the power transmission member has an enlarged portion formed thicker than other portions of the power transmission member, and still further the enlarged portion includes a pretensioner made of the same material as the power transmission member. 
     In the above-described pretensioner, retractor and seat belt device, the enlarged portion may be formed such that a length in an axial direction of the power transmission member is smaller than a pitch of the ring gear. 
     Further, the pretensioner may include a guide block arranged at a meshing start portion between the ring gear and the power transmission member and the guide block may have a slope for guiding movement of the power transmission member and a main body portion fixed to a base frame surrounding the spool. 
     Advantageous Effects of Invention 
     According to the above-described pretensioner, retractor, and seat belt device of the invention, by forming the enlarged portion at the tip end of the power transmission member, the enlarged portion first collides with the ring gear when the pretensioner is operated. Thus, the thick portion of the power transmission member can collide with the ring gear in the initial driving stage. As a result, the strength of the power transmission member can be secured. In addition, since the portion behind the enlarged portion of the power transmission member is formed thinner than the enlarged portion, the engagement depth of the ring gear in the steady driving stage can be reduced. As a result, the resistance accompanying the increase in the number of engagement teeth can be reduced. 
     Therefore, according to the invention, it is possible to achieve both the securing of the strength of the power transmission member in the initial driving stage and the reduction of the sliding resistance against the power transmission member in the steady driving stage. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an exploded view of components illustrating a retractor according to an embodiment of the invention. 
         FIGS. 2A and 2B  are cross-sectional views of a pretensioner illustrated in  FIG. 1 , where  FIG. 2A  illustrates a non-operating state and  FIG. 2B  illustrates an enlarged view of a tip end of a power transmission member. 
         FIGS. 3A and 3B  are cross-sectional views of the pretensioner illustrated in  FIG. 1 , where  FIG. 3A  illustrates an initial operation state and  FIG. 3B  illustrates an intermediate operation stage. 
         FIGS. 4A to 4E  are views illustrating modification examples of an enlarged portion, where  FIG. 4A  illustrates a first modification example,  FIG. 4B  illustrates a second modification example,  FIG. 4C  illustrates a third modification,  FIG. 4D  illustrates a fourth modification, and  FIG. 4E  illustrates a fifth modification example. 
         FIG. 5A to 5E  are views illustrating modification examples of the enlarged portion, where  FIG. 5A  illustrates a sixth modification example,  FIG. 5B  illustrates a seventh modification example,  FIG. 5C  illustrates an eighth modification example,  FIG. 5D  illustrates a ninth modification example, and  FIG. 5E  illustrates a tenth modification example. 
         FIG. 6  is an overall configuration diagram illustrating a seat belt device according to the embodiment of the invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the invention will be described with reference to  FIGS. 1 to 6 . Here,  FIG. 1  is an exploded view of components illustrating a retractor according to an embodiment of the invention.  FIGS. 2A and 2B  are cross-sectional views of a pretensioner illustrated in  FIG. 1 , where  FIG. 2A  illustrates a non-operating state and  FIG. 2B  illustrates an enlarged view of a tip end of a power transmission member.  FIGS. 3A and 3B  are cross-sectional views of the pretensioner illustrated in  FIG. 1 , where  FIG. 3A  illustrates an initial operation state and  FIG. 3B  illustrates an intermediate operation stage. In  FIG. 2B , the left diagram illustrates a front view of the power transmission member and the right diagram illustrates a partial side view of the power transmission member. 
     As illustrated in  FIG. 1 , a retractor  1  according to an embodiment of the invention includes a spool  2  which winds up a webbing which restrains an occupant and a pretensioner  3  which winds up webbing in an emergency to remove slack. The pretensioner  3  includes a ring gear  31  connected to the spool  2  and a power transmission device  32  which transmits power to the ring gear  31  in an emergency. The power transmission device  32  includes a rod-shaped power transmission member  32   a  which transmits power to the ring gear  31  while being plastically deformed. A tip end of the power transmission member  32   a  has an enlarged portion  32   b  which is formed thicker than other portions of the power transmission member  32   a . The enlarged portion  32   b  is made of the same material as the power transmission member  32   a . In  FIG. 1 , the illustration of the webbing is omitted. 
     The spool  2  is a winding drum which winds up the webbing and is rotatably accommodated in a base frame  11  which forms a skeleton of the retractor  1 . The base frame  11  has, for example, a pair of end surfaces  111  and  112  facing each other and a side surface  113  connecting these end surfaces. The base frame  11  may have a tie plate  114  facing the side surface  113  and connected to the end surfaces  111  and  112 . Further, for example, a spring unit  4  is arranged on the end face  111  side and the pretensioner  3  and a lock mechanism  5  are arranged on the end face  112  side. The arrangement of the spring unit  4 , the pretensioner  3 , the lock mechanism  5 , and the like is not limited to the illustrated configuration. 
     An opening portion  111   a  is formed in the end surface  111  of the base frame  11  to insert the shaft portion of the spool  2  and the end surface  112  of the base frame  11  is formed with an opening portion  112   a  having internal teeth which can be engaged with a pawl (not illustrated) of the lock mechanism  5 . A part (for example, the ring gear  31 ) of the pretensioner  3  is arranged inside the end surface  112  of the base frame  11 . Further, the lock mechanism  5  is disposed outside the end surface  112  of the base frame  11  and the lock mechanism  5  is accommodated in a retainer cover  51 . 
     The retainer cover  51  may be provided with a vehicle sensor  6  for detecting sudden deceleration or inclination of a vehicle body. The vehicle sensor  6  has, for example, a spherical mass body and a sensor lever which is swung by the movement of the mass body. The vehicle sensor  6  is fitted and fixed in the opening portion  112   b  formed on the end surface  112  of the base frame  11 . 
     The spool  2  has a cavity in the center portion and a torsion bar  21  forming an axis may be inserted therethrough. The torsion bar  21  has a first end portion connected to a locking base  52  of the lock mechanism  5  connected to an end portion of the spool  2  and a second end portion connected to a spring core of the spring unit  4 . Therefore, the spool  2  is connected to the spring unit  4  via the locking base  52  and the torsion bar  21  and is urged by a power spring accommodated in the spring unit  4  in a direction of winding the webbing. 
     The first end portion of the torsion bar  21  may be connected to the spool  2  without passing through the locking base  52 . The means for applying the winding force to the spool  2  is not limited to the spring unit  4 , but may be another means using an electric motor or the like. 
     The locking base  52  is provided with a pawl arranged so as to be able to protrude or emerge from the side surface portion. When the lock mechanism  5  is operated, by protruding the pawl from the side surface portion of the locking base  52 , the pawl is engaged with the internal teeth formed in the opening portion  112   a  of the base frame  11 , in such a manner that the rotation of the locking base  52  in a webbing withdrawal direction is restricted. 
     Therefore, even when a load is applied in the webbing withdrawal direction in a state where the lock mechanism  5  is operated, until a load equal to or greater than a threshold value is applied to the torsion bar  21 , the spool  2  can be kept in a non-rotating state. When a load equal to or greater than the threshold value is applied to the torsion bar  21 , the torsion bar  21  is twisted, so that the spool  2  relatively rotates and the webbing is pulled out. 
     Further, the lock mechanism  5  includes a lock gear  53  arranged so as to be adjacent to the locking base  52 . The lock gear  53  includes a flywheel (not illustrated) which is swingably disposed. When the speed of the webbing is faster than a normal withdrawal speed, the flywheel swings and engages with the internal teeth (not illustrated) formed on the retainer cover  51 . When the vehicle sensor  6  is operated, the sensor lever engages with external teeth formed on the side surface of the lock gear  53 . 
     Thus, in the case of the lock gear  53 , the rotation of the lock gear  53  is regulated by the operation of the flywheel or the vehicle sensor  6 . When the rotation of the lock gear  53  is restricted, relative rotation occurs between the locking base  52  and the lock gear  53  and the pawl protrudes from the side surface portion of the locking base  52  with the relative rotation. 
     In addition, the lock mechanism  5  is not limited to the configuration illustrated in the drawing and various configurations existing in the related art can be arbitrarily selected and used. 
     The pretensioner  3  includes, for example, the ring gear  31  arranged coaxially with the spool  2 , the power transmission device  32  for rotating the ring gear  31 , a pretensioner cover  33  for accommodating the ring gear  31 , a guide spacer  34  forming a moving space for the power transmission member  32   a , and a guide block  35  arranged at the start point of engagement between the ring gear  31  and the power transmission member  32   a.    
     The pretensioner cover  33  is arranged inside the end surface  112  of the base frame  11  and the guide spacer  34  is accommodated in the pretensioner cover  33 . The ring gear  31  is arranged such that the ring gear  31  is located in the space between the pretensioner cover  33  and the end surface  112  secured by the guide spacer  34 . 
     The ring gear  31  is fixed to, for example, a shaft portion of the locking base  52 . As illustrated in  FIG. 2A , the ring gear  31  has a plurality of engagement teeth  31   a  formed to protrude radially outward. In addition, the ring gear  31  may be called a pinion gear. 
     The power transmission device  32  includes, for example, the rod-shaped power transmission member  32   a  which transmits power to the ring gear  31  while plastically deforming, a pipe  32   c  for accommodating the power transmission member  32   a , a gas generator  32   d  disposed at an end portion of the pipe  32   c , and a piston  32   e  sliding in the pipe  32   c.    
     In the pipe  32   c , a tip end is located at a position facing the engagement teeth  31   a  of the ring gear  31  and a rear end side is extended by the length necessary for the movement of the power transmission member  32   a . Also, the pipe  32   c  is formed so as to be curved along the outer shape of the retractor  1 . As illustrated in  FIG. 1 , an opening portion  32   g  is formed at a part of the outer periphery of the tip end of the pipe  32   c  and the power transmission member  32   a  is discharged into the pretensioner cover  33  from the opening portion  32   g.    
     Also, as illustrated in  FIG. 2A , the guide block  35  is inserted into the tip end of the pipe  32   c  and the guide block  35  and the tip end of the pipe  32   c  are fixed to the side surface  113  of the base frame  11  by a fixing pin  36 . The guide block  35  has a slope  35   a  for guiding the movement of the power transmission member  32   a  and a main body portion  35   b  fixed to the base frame  11  (side surface  113 ). 
     As illustrated in  FIG. 1 , the guide block  35  has a columnar shape which can be inserted into the tip end of the pipe  32   c  and has the slope  35   a  formed on its end surface. The guide block  35  is a component which guides the tip end of the power transmission member  32   a  to collide with the engagement teeth  31   a  of the ring gear  31  when the pretensioner  3  is operated. The slope  35   a  may be flat or curved as long as the slope  35   a  can guide the power transmission member  32   a.    
     The guide block  35  is also a component which receives an impact generated when the power transmission member  32   a  collides with the engagement teeth  31   a . Therefore, the guide block  35  may be made of resin or metal as long as the guide block  35  has enough strength to withstand the load generated when the power transmission member  32   a  collides with the engagement teeth  31   a . The guide block  35  is fixed to the base frame  11  having high strength by the fixing pin  36 . Therefore, the power transmission member  32   a  can be guided to the ring gear  31  without being deformed or displaced when the pretensioner  3  is operated, and without escaping the power transmission member  32   a.    
     The power transmission member  32   a  has, for example, an elongated shape (rod shape) made of resin and is accommodated in the pipe  32   c . As illustrated in  FIG. 2B , in the power transmission member  32   a , the enlarged portion  32   b  formed thicker than other portions of the power transmission member  32   a  is provided at the tip end. The enlarged portion  32   b  is obtained by enlarging the tip end of the power transmission member  32   a  and is made of the same material as the power transmission member  32   a . A transition portion  32   h  between the enlarged portion  32   b  and another portion may have a tapered surface. 
     Here, assuming that the thickness of the portion other than the enlarged portion  32   b  of the power transmission member  32   a  is set as Dr and the thickness of the enlarged portion  32   b  is set as Dt, the power transmission member  32   a  has a relationship of Dt&gt;Dr. The difference (the magnitude of Dt−Dr) between the enlarged portion  32   b  and the other portions is set to, for example, about 10% to 15% of Dr. 
     The enlarged portion  32   b  is formed such that the length in the axial direction of the power transmission member  32   a  is smaller than the pitch (the distance between the tip end portions of the adjacent engagement teeth  31   a ) of the ring gear  31 . Specifically, assuming that the axial length of the enlarged portion  32   b  is set as W and the pitch of the ring gear  31  is set as P, the enlarged portion  32   b  has a relationship of W&lt;P. With this configuration, interference between the enlarged portion  32   b  and the engagement teeth  31   a  can be avoided. 
     The power transmission device  32  having the enlarged portion  32   b  is normally (when the pretensioner  3  is not operated) kept in a state where the power transmission member  32   a  is accommodated in the pipe  32   c  as illustrated in  FIG. 2A . In an emergency (when the pretensioner  3  is operating) such as a vehicle collision, the power transmission member  32   a  is pushed out of the pipe  32   c  by the gas supplied by the gas generator  32   d.    
     The power transmission member  32   a  pushed out of the pipe  32   c  moves along the slope  35   a  of the guide block  35  and collides with the engagement teeth  31   a  of the ring gear  31 , as illustrated in  FIG. 3A . In this case, since the enlarged portion  32   b  first collides with the engagement teeth  31   a  of the ring gear  31 , the thick portion of the power transmission member  32   a  can collide with the ring gear  31  in the initial driving stage. As a result, the strength of the power transmission member  32   a  can be secured. 
     Then, as illustrated in  FIG. 3B , the power transmission member  32   a  is pushed out into a space (passage) formed by the pretensioner cover  33  and the guide spacer  34  and moves along the passage while engaging with the engagement teeth  31   a  of the ring gear  31 . In this case, about 4 to 5 engagement teeth  31   a  are engaged with the power transmission member  32   a  and the ring gear  31  is rotating and a stage in which a state is shifted to that state is referred to as a steady driving stage. 
     In such a steady driving stage, since the enlarged portion  32   b  of the power transmission member  32   a  has passed through the ring gear  31 , the ring gear  31  engages with other portions of the power transmission member  32   a  other than the enlarged portion  32   b . The other portion behind the enlarged portion  32   b  is formed thinner than the enlarged portion  32   b , so that the engagement depth of the engagement teeth  31   a  can be reduced. Therefore, the resistance caused by the increase in the number of engagement teeth of the ring gear  31  can be reduced. 
     Then, the power transmission member  32   a  finally stops by colliding with a stopper surface  34   a  formed by the guide spacer  34  or finishing winding up the slack of the webbing. 
     In the embodiment, a case where the pretensioner  3  has the guide block  35  is described, but the power transmission member  32   a  having the enlarged portion  32   b  can be applied to a pretensioner of the related art which does not have the guide block. 
     In this embodiment, the “tip end” of the power transmission member  32   a  or the pipe  32   c  means the end portion of the power transmission member  32   a  on a movement-direction front side (the side close to the engagement teeth  31   a  of the ring gear  31 ) when the pretensioner  3  operates and the “rear end” of the power transmission member  32   a  or the pipe  32   c  means the end portion of the power transmission member  32   a  on a movement-direction rear side (the side close to the gas generator  32   d ) when the pretensioner  3  is operated. 
     Next, modification examples of the enlarged portion  32   b  will be described with reference to  FIGS. 4A to 4D . Here,  FIGS. 4A to 4E  are views illustrating modification examples of the enlarged portion, where  FIG. 4A  illustrates a first modification example,  FIG. 4B  illustrates a second modification example,  FIG. 4C  illustrates a third modification example,  FIG. 4D  illustrates a fourth modification example, and  FIG. 4E  illustrates a fifth modification example.  FIGS. 5A to 5E  are views illustrating the modification examples of the enlarged portion, where  FIG. 5A  illustrates a sixth modification example,  FIG. 5B  illustrates a seventh modification example,  FIG. 5C  illustrates an eighth modification example,  FIG. 5D  illustrates a ninth modification example, and  FIG. 5E  illustrates a tenth modification example. In each of  FIGS. 4A to 5E , the left diagram is a front view of the power transmission member  32   a  and the right diagram is a partial side view of the power transmission member  32   a.    
     In the first modification example illustrated in  FIG. 4A , a tapered surface is formed (chamfered) at an outer peripheral edge portion  32   i  of the enlarged portion  32   b . According to the first modification example, the slidability of the power transmission member  32   a  can be improved. 
     In the second modification example illustrated in  FIG. 4B , the enlarged portion  32   b  is eccentric with respect to the other portion of the power transmission member  32   a . Thus, even when the enlarged portion  32   b  is eccentric, it can be formed thicker than the other portions. Also, by arranging the side (the lower side in the figure) where the transition portion  32   h  of the enlarged portion  32   b  is flat on the guide block  35  side and arranging the side where the transition portion  32   h  protrudes on the ring gear  31  side, the slidability of the power transmission member  32   a  can be improved. 
     In the third modification example illustrated in  FIG. 4C , the enlarged portion  32   b  is formed in a truncated cone shape. In the fourth modification example illustrated in  FIG. 4D , the enlarged portion  32   b  is formed in a substantially spherical shape. In the fifth modification example illustrated in  FIG. 4E , the enlarged portion  32   b  is formed in a shape in which both end portions of spheres bodies are cut off. 
     In the sixth modification example illustrated in  FIG. 5A , the enlarged portion  32   b  is formed by a cylindrical portion  32   j  and a spherical portion  32   k . In the seventh modification example illustrated in  FIG. 5B , the enlarged portion  32   b  is formed by the cylindrical portion  32   j  and a conical portion  32   m . In the eighth modification example illustrated in  FIG. 5C , the enlarged portion  32   b  is formed in a shape in which bottom portions of a pair of frustoconical portions  32   n  are in contact with each other. 
     In the ninth modification example illustrated in  FIG. 5D  and the tenth modification example illustrated in  FIG. 5E , the enlarged portion  32   b  is formed in a serrated shape (sawtooth shape). In the ninth modification example, the irregularities formed on the outer periphery of the enlarged portion  32   b  have a square shape. In the tenth modification example, the irregularities formed on the outer periphery of the enlarged portion  32   b  have a smooth shape. 
     The third to tenth modification examples described above also exhibit substantially the same effects as the embodiment shown in  FIG. 2B . The first to tenth modification examples are examples of the enlarged portion  32   b  and are not limited to the illustrated shapes. 
     Next, a seat belt device according to an embodiment of the invention will be described with reference to  FIG. 6 . Here,  FIG. 6  is an overall configuration diagram illustrating the seat belt device according to the embodiment of the invention. In  FIG. 6 , for convenience of explanation, components other than the seat belt device are illustrated by dashed lines. 
     A seat belt device  100  according to the embodiment illustrated in  FIG. 6  includes a webbing W to restrain an occupant, the retractor  1  for winding the webbing W, a guide anchor  101  provided on the vehicle body side for guiding the webbing W, a belt anchor  102  for fixing the webbing W to the vehicle body side, a buckle  103  arranged on the side surface of a seat S, and a tongue  104  disposed on the webbing W. The retractor  1  has, for example, the configuration illustrated in  FIG. 1 . 
     Hereinafter, components other than the retractor  1  will be briefly described. The seat S includes, for example, a seat portion S 1  on which an occupant sits, a backrest portion S 2  located on the back of the occupant, and a headrest portion S 3  for supporting the head of the occupant. The retractor  1  is built in, for example, a B pillar P of a vehicle body. In general, the buckle  103  is often arranged on the side surface of the seat S 1  and the belt anchor  102  is often arranged on the lower surface of the seat S 1 . Further, the guide anchor  101  is often arranged on the B pillar P. The webbing W has one end connected to the belt anchor  102  and the other end connected to the retractor  1  via the guide anchor  101 . 
     Therefore, when the tongue  104  is fitted to the buckle  103 , the webbing W is pulled out from the retractor  1  while sliding in the insertion hole of the guide anchor  101 . Further, when the occupant wears the seat belt or releases the seat belt at the time of dismounting, the webbing W is wound up by the spring unit  4  of the retractor  1  until a certain load is applied. 
     The seat belt device  100  described above is obtained by applying the retractor  1  according to the embodiment described above to a normal seat belt device in a front seat. Therefore, according to the seat belt device  100  of the embodiment, by forming the enlarged portion  32   b  at the tip end of the power transmission member  32   a , it is possible to achieve both the securing of the strength of the power transmission member  32   a  in the initial driving stage and the reduction of the sliding resistance to the power transmission member  32   a  in the steady driving stage. 
     The seat belt device  100  according to the embodiment is not limited to application to a front seat and can be easily applied to a rear seat, for example, by omitting the guide anchor  101 . Further, the seat belt device  100  according to the embodiment can be used for vehicles other than automobiles. 
     The invention is not limited to the embodiments described above and it goes without saying that various modifications can be made without departing from the spirit of the present invention. 
     REFERENCE SIGNS LIST 
     
         
           1  retractor 
           2  spool 
           3  pretensioner 
           4  spring unit 
           5  lock mechanism 
           6  vehicle sensor 
           11  base frame 
           21  torsion bar 
           31  ring gear 
           31   a  engagement teeth 
           32  power transmission device 
           32   a  power transmission member 
           32   b  enlarged portion 
           32   c  pipe 
           32   d  gas generator 
           32   e  piston 
           32   g  opening portion 
           32   h  transition portion 
           32   i  outer peripheral edge portion 
           32   j  cylindrical portion 
           32   k  spherical portion 
           32   m  conical portion 
           32   n  frustoconical portion 
           33  pretensioner cover 
           34  guide spacer 
           34   a  stopper surface 
           35  guide block 
           35   a  slope 
           35   b  main body portion 
           36  fixing pin 
           51  retainer cover 
           52  locking base 
           53  lock gear 
           100  seat belt device 
           101  guide anchor 
           102  belt anchor 
           103  buckle 
           104  tongue 
           111 ,  112  end surface 
           111   a ,  112   a ,  112   b  opening portion 
           113  side surface 
           114  tie plate