Patent Publication Number: US-2018043859-A1

Title: Pretensioner, retractor and seat belt device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Japanese Patent Application No. 2016-157180, filed on Aug. 10, 2016, the entire contents of which are hereby incorporated by reference, the same as if set forth at length, the entire of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to a pretensioner, a retractor and a seat belt device, and particularly to a pretensioner, a retractor, and a seat belt device which use a resin-made long body as a power transmission member. 
     BACKGROUND ART 
     In a vehicle such as an automobile, generally, a seat belt device which restrains an occupant is provided in a seat including a seating part on which the occupant sits and a backrest part positioned on the back surface side of the occupant. Such a seat belt device includes a webbing which restrains the occupant, a retractor which performs winding of the webbing, a guide anchor which is provided in a vehicle body and guides the webbing, a belt anchor which fixes the webbing in the vehicle body, a buckle which is disposed on the side surface of the seat, and a tongue which is disposed in the webbing. When the tongue is fitted into the buckle, the occupant is restrained in the seat by the webbing. 
     In the retractor, a pretensioner which removes the looseness of the webbing during an emergency such as a collision of the vehicle is disposed in many cases. In addition, recently, it is considered that a resin column-shaped rack (resin rod) is used as a moving member (power transmission member) which rotates a spool at the time of the emergency (for example, JP-A-2014-201156 and WO 2014/194993 A). 
     SUMMARY OF INVENTION 
     In the pretensioner described in JP-A-2014-201156, the movement energy of the moving member (power transmission member) which rotates the spool is reduced in a second area and an engaging part, and finally, the movement is stopped by engaging the moving member (power transmission member) in the engaging part. In such a pretensioner, the resin column-shaped rack (resin rod) is engaged in a driving wheel (pinion). Therefore, when the movement of the resin column-shaped rack (resin rod) is stopped, the rotation of the spool is stopped, and the winding of the webbing is stopped. 
     Therefore, in order to secure a certain winding amount of the webbing, it is necessary to make the resin column-shaped rack (resin rod) long, and it is necessary to form a place (containing part) where the resin column-shaped rack (resin rod) is escaped after rotating the driving wheel (pinion). That is, the maximum winding amount of the webbing depends on the length of the resin column-shaped rack (resin rod) and the capacitance of the containing part thereof. 
     As a result, the conventional pretensioner has a problem that the pretensioner becomes enlarged in order to increase the maximum winding amount of the webbing, and the maximum winding amount of the webbing becomes small in order to miniaturize the pretensioner. 
     In the pretensioner described in WO 2014/194993 A, it is necessary that the resin-made long body which rotates the driving wheel is peeled off from the driving wheel, and it is expected that the resin-made long body can be hardly operated smoothly as described in WO 2014/194993 A. In addition, the resin-made long body is peeled off to be detoured and is engaged in the driving wheel again. However, it is expected that an approaching angle with respect to the tangential direction of the driving wheel is large, and the resin-made long body can be hardly engaged in the driving wheel while the rotation of the driving wheel is maintained. 
     In the pretensioner described in WO 2014/194993 A, the resin-made long body is detoured, and thus there is a problem that the pretensioner is enlarged similarly to that of JP-A-2014-201156. 
     The present embodiment has been made in consideration of the above-described problems, and an object thereof is to provide a pretensioner, a retractor, and a seat belt device in which a maximum winding amount of a webbing is increased while an enlargement of the pretensioner is suppressed. 
     A pretensioner includes a driving wheel and a power transmission unit. A spool is disposed to be rotatable in the driving wheel. The spool winds a webbing which restrains an occupant. The power transmission unit transmits power to the driving wheel during an emergency. 
     The power transmission unit includes a resin-made long body, a pipe and a gas generator. The resin-made long body rotates the driving wheel. The pipe contains the resin-made long body. The gas generator supplies an operation gas into the pipe. The resin-made long body discharged from the pipe is configured to rotate the driving wheel while the resin-made long body is wound around the driving wheel. 
     A retractor includes a spool and a pretensioner. The spool winds a webbing which restrains an occupant. The pretensioner removes a looseness by winding the webbing during an emergency. The pretensioner includes a driving wheel and a power transmission unit. A spool is disposed to be rotatable in the driving wheel. The spool winds a webbing which restrains an occupant. The power transmission unit transmits power to the driving wheel during an emergency. The power transmission unit includes a resin-made long body, a pipe and a gas generator. The resin-made long body rotates the driving wheel. The pipe contains the resin-made long body. The gas generator supplies an operation gas into the pipe. The resin-made long body discharged from the pipe is configured to rotate the driving wheel while the resin-made long body is wound around the driving wheel. 
     A seat belt device includes a webbing, a retractor, a belt anchor, a buckle and a tongue. The webbing restrains an occupant. The retractor winds the webbing. The belt anchor fixes the webbing in a vehicle body. The buckle is disposed on a side surface of the seat. The tongue is disposed in the webbing. The retractor includes a spool which winds the webbing, and a pretensioner which removes a looseness by winding the webbing during an emergency. The pretensioner includes a driving wheel and a power transmission unit. A spool is disposed to be rotatable in the driving wheel. The spool winds a webbing which restrains an occupant. The power transmission unit transmits power to the driving wheel during an emergency. The power transmission unit includes a resin-made long body, a pipe and a gas generator. The resin-made long body rotates the driving wheel. The pipe contains the resin-made long body. The gas generator supplies an operation gas into the pipe. The resin-made long body discharged from the pipe is configured to rotate the driving wheel while the resin-made long body is wound around the driving wheel. 
     In the pretensioner, the retractor and the seat belt described above, the resin-made long body may have a length shorter than an outer circumferential length of the driving wheel, and may have at least a length longer than a half of the outer circumferential length. 
     The pretensioner may include a cover member which covers an outer circumference of the driving wheel. The cover member may be configured to form a passage of the resin-made long body. 
     In the pretensioner, the retractor, and the seat belt device according to the above-described present embodiment, the driving wheel is configured to be rotated while the resin-made long body is wound around the driving wheel. Therefore, the driving wheel can be continuously rotated by the inertial force of the resin-made long body until the resin-made long body becomes still, and the maximum winding amount of the webbing can be increased. 
     Since a state where the resin-made long body is wound around the driving wheel is held, it is unnecessary to secure a space to contain the resin-made long body peeled off from the driving wheel, and it is possible to suppress the enlargement of the pretensioner. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a developed view illustrating components of a retractor according to one embodiment of the present embodiment; 
         FIGS. 2A and 2B  are partially sectional views of a pretensioner illustrated in  FIG. 1 .  FIG. 2A  illustrates an initial state, and  FIG. 2B  illustrates an operation-proceeding state (first rotation); 
         FIGS. 3A and 3B  are partially sectional views of the pretensioner illustrated in  FIG. 1 .  FIG. 3A  illustrates an operation-ending state (second rotation), and  FIG. 3B  illustrates a modification; 
         FIG. 4  is a diagram for explaining an effect of the pretensioner illustrated in  FIG. 1 ; and 
         FIG. 5  is an entire configuration view illustrating a seat belt device according to the embodiment of the present embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, the embodiment of the present embodiment will be described with reference to  FIGS. 1 to 4 . Herein,  FIG. 1  is a developed view illustrating components of a retractor according to the embodiment of the present embodiment.  FIGS. 2A and 2B  are sectional views partially illustrating the pretensioner illustrated in  FIG. 1 .  FIG. 2A  illustrates an initial state, and  FIG. 2B  illustrates an operation-proceeding state (first rotation).  FIGS. 3A and 3B  are sectional views partially illustrating the pretensioner illustrated in  FIG. 1 .  FIG. 3A  illustrates an operation-ending state (second rotation), and  FIG. 3B  illustrates a modification.  FIG. 4  is a diagram for explaining an effect of the pretensioner illustrated in  FIG. 1 . 
     For example, as illustrated in  FIGS. 1 to 3B , the retractor  1  according to the embodiment of the present embodiment includes a spool  2  which performs winding of a webbing which restrains an occupant, and a pretensioner  3  which removes a looseness by winding the webbing during an emergency. The pretensioner  3  includes a driving wheel  4  which is disposed such that the spool  2  is rotatable, and a power transmission unit  5  which transmits a power to the driving wheel  4  during the emergency. The power transmission unit  5  includes a resin-made long body  51  which rotates the driving wheel  4 , a pipe  52  which contains the resin-made long body  51 , and a gas generator  53  which supplies an operation gas into the pipe  52 . The resin-made long body  51  discharged from the pipe  52  is configured to rotate the driving wheel  4  while the resin-made long body is wound around the driving wheel  4 . 
     The spool  2  is a winding drum which winds the webbing, and is rotatably contained in the base frame  11  forming a frame of the retractor  1 . For example, the base frame  11  has a pair of end surfaces  111  and  112  which confront each other, and a side surface  113  which connects the end surfaces. The base frame  11  may have a tie plate  114  which confronts the side surface  113  and is connected with the end surfaces  111  and  112 . In addition, for example, a spring unit  12  is disposed on the end surface  111 , and the pretensioner  3  and a lock mechanism  13  are disposed on the end surface  112 . Incidentally, the arrangement of the spring unit  12 , the pretensioner  3 , the lock mechanism  13 , and the like is not limited to the illustrated one. 
     An opening  111   a  through which the spool  2  is inserted is formed in the end surface  111  of the base frame  11 , and an opening  112   a  which has internal teeth engageable with a pawl  131  of the lock mechanism  13  is formed in the end surface  112  of the base frame  11 . In addition, a portion (for example, the driving wheel  4  and the cover member  56 ) of the pretensioner  3  is disposed on the inside of the end surface  112  of the base frame  11 . In addition, the lock mechanism  13  is disposed on the outside of the end surface  112  of the base frame  11 , and the lock mechanism  13  is contained in the retainer cover  14 . 
     A vehicle sensor  15  which detects the sharp deceleration of the vehicle body may be disposed in the retainer cover  14 . For example, the vehicle sensor  15  has a spherical mass body, and a sensor lever which is swung by the movement of the mass body. The vehicle sensor  15  may be fitted into the opening formed in the end surface  112  of the base frame  11 . 
     The spool  2  has a hollow in the central portion, and a torsion bar  16  forming an axial center is inserted thereto. In addition, one end of the spool  2  is connected with the spring core  12   a  of the spring unit  12 . The spring unit  12  includes a flat spiral spring  12   b  connected with the spring core  12   a,  a spring case  12   c  which contains the flat spiral spring  12   b,  and a spring cover  12   d  which covers those components. The spring core  12   a  is rotatably supported by the spring case  12   c  and the spring cover  12   d.    
     Incidentally, a configuration in which a winding force is applied to the spool  2  is not limited to the illustrated configuration. In addition, in  FIG. 1 , the reference numeral  17  denotes a shaft bearing. 
     The other end of the torsion bar  16  is connected with a locking base  132  of the lock mechanism  13 . As described later, the locking base  132  is configured to be engaged in the base frame  11 , and can switch the torsion bar  16  between a rotating state and a non-rotating state. Therefore, in a state where the lock mechanism  13  is operated (a state where the locking base  132  is engaged with the base frame  11 ), even in a case where the load is applied in a direction to draw the webbing, the spool  2  can be held in the non-rotating state until a load of a threshold or more is generated in the torsion bar  16 . Further, in the case where the load of the threshold or more is generated in the torsion bar  16 , the spool  2  relatively generates a rotational movement when the torsion bar  16  is twisted, and the webbing is drawn. 
     The lock mechanism  13  includes the locking base  132  connected with the end of the torsion bar  16 , the pawl  131  which is movably disposed in the locking base  132 , a cover plate  133  for regulating an axial movement of the pawl  131 , a lock gear  134  which is rotatably disposed on the outside of the locking base  132 , and a flywheel  135  which is swingably disposed in the lock gear  134 . 
     Incidentally, the lock mechanism  13  is not limited to the illustrated configuration, and various configurations having known from the past may be arbitrarily selected to be used. In addition, in  FIG. 1 , the reference numeral  136  denotes a bearing cap, the reference numeral  137  denotes a pawl spring, and the reference numeral  138  denotes a hook spring. 
     The locking base  132  has a circular disc part  132   a,  a polygonal columnar driving wheel supporting part  132   b  which is formed on the spool  2  side of the disc part  132   a  and supports the driving wheel  4 , and a torsion bar supporting part  132   c  into which the other end of the torsion bar  16  is inserted. In the illustrated embodiment, the spool  2 , the torsion bar  16 , the locking base  132 , and the like are disposed to be coaxial with each other, so as to form a rotational axis of the spool  2 . 
     Incidentally, herein, the description has been given about a case where the driving wheel  4  is fixed in the locking base  132 , but the present embodiment is not limited to such a configuration. For example, the rotation of the driving wheel  4  may be transmitted to the spool  2  through a pinion gear by inserting the pinion gear connected with the spool  2  into the driving wheel  4 , and engaging the internal teeth of the driving wheel  4  with the external teeth of the pinion gear as needed. 
     According to the lock mechanism  13  having the above-described configuration, in a case where the webbing is drawn at a rate higher than a normal drawing rate, that is, in a case where the drawing acceleration of the webbing exceeds a predetermined threshold, the flywheel  135  is swung to be engaged with the internal teeth  14   a  of the retainer cover  14 , so as to regulate the rotation of the lock gear  134 . In addition, in a case where the vehicle sensor  15  is operated, the sensor lever is engaged with the external teeth of the lock gear  134 , so as to regulate the rotation of the lock gear  134 . 
     Further, when the rotation of the lock gear  134  is regulated, a relative rotation is generated between the locking base  132  and the lock gear  134 , and the pawl  131  is moved outward in the radial direction according to the relative rotation, so that the tip of the pawl  131  is engaged in the internal teeth formed in the opening  112   a  of the base frame  11  (that is, the locking base  132  is engaged with the base frame  11  through the pawl  131 ). As a result, the rotation of the locking base  132  is regulated, and the rotation of the spool  2  also is regulated. Therefore, the drawing of the webbing is locked. 
     Incidentally, at a normal time (a case where the drawing acceleration of the webbing is equal to or less than a predetermined threshold), the lock mechanism  13  is not operated, and the locking base  132  and the lock gear  134  are rotated together according to the rotation of the spool  2 . Therefore, at the normal time, since the locking base  132  and the lock gear  134  are not relatively rotated, the pawl  131  is configured to maintain the state where the pawl retracts to a position not to interfere with the internal teeth formed in the opening  112   a  of the base frame  11 . 
     The pretensioner  3  is a component which rotates the driving wheel  4  by the power transmission unit  5  during the emergency such as the collision of the vehicle so as to remove the looseness of the webbing. Similarly to the conventional power transmission unit  5 , the power transmission unit  5  has the resin-made long body  51  as a power transmission member, the pipe  52 , the gas generator  53 , a piston  54 , a stopper spring  55 , and the cover member  56 . 
     The resin-made long body  51  is a resin-made long member (so-called resin rod) which is plastically deformable. Herein, the “long body” means an object of which the length is sufficiently long (for example, at least several times to several ten times) with respect to a diameter. For example, the resin-made long body  51  has a length which is shorter than the outer circumferential length of the driving wheel  4 . The outer circumferential length of the driving wheel  4  may be defined by a tip position of teeth  41  of the driving wheel  4 , may be defined by an intermediate position (for example, a position of half the height of the teeth  41 ) of the teeth  41  of the driving wheel  4 , or may be defined by a root position of the teeth  41  of the driving wheel  4 . 
     The resin-made long body  51  is extruded by a gas pressure when the rear end thereof is in the state of being contained in the pipe  52 , and thus a certain load can be supplied to the driving wheel  4 . Therefore, preferably, the resin-made long body  51  has a certain length or more, and preferably has a length equal to or more than at least half (50%) of the outer circumferential length of the driving wheel  4 . 
     In a case where it is demanded that the resin-made long body  51  is extruded over a longer time, the length of the resin-made long body  51  may be set to be equal to or more than a 75% length of the outer circumferential length of the driving wheel  4 , may be set to be equal to or more than a 90% length thereof, or may be set to be equal to or more than a 95% length thereof. However, the length of the resin-made long body  51  is set not to exceed a 100% length of the outer circumferential length of the driving wheel  4 . 
     Incidentally, in the illustrated embodiment, the resin-made long body  51  is provided as a single molding body. However, the resin-made long body  51  is not necessarily one body, and may be divided to a plurality of bodies. 
     The pipe  52  is a pressure vessel which forms an injection cylinder of the resin-made long body  51 . It is necessary that the pipe  52  has a certain length, and thus the pipe  52  is bent to be disposed along the side surface of the base frame  11 . The gas generator  53  is mounted in the rear end of the pipe  52 . The piston  54  receives the operation gas supplied from the gas generator  53 , and is formed to be slid while sealing the inside surface of the pipe  52 . The stopper spring  55  is a component which forms a space for supplying the operation gas to between the gas generator  53  and the piston  54 . 
     As illustrated in  FIGS. 2A and 2B , the cover member  56  is configured to cover the outer circumference of the driving wheel  4 , and to form a passage  56   a  of the resin-made long body  51 . Specifically, the cover member  56  includes a side surface  56   b  which covers the outer circumference of the driving wheel  4 , a top plate  56   c  which regulates the movement of the resin-made long body  51  in an axial direction of the spool  2 , and a plurality of taps  56   d  which are engaged with the base frame  11 . The passage  56   a  is configured by the space formed among the cover member  56  (the side surface  56   b  and the top plate  56   c ), the driving wheel  4 , and the base frame  11  (end surface  112 ). 
     As illustrated in  FIG. 1 , the side surface  56   b  has a substantially cylindrical shape. The engaging amount of the resin-made long body  51  into the driving wheel  4  can be adjusted by adjusting a radial size of the side surface  56   b.  In addition, the top plate  56   c  has a substantially ring shape, and components configuring a shaft system of the pretensioner  3  are inserted into the opening of the central portion. 
     As illustrated in  FIG. 2A , the pipe  52  is connected with the side surface  56   b  of the cover member  56 , and the resin-made long body  51  discharged from the pipe  52  is moved along the inside surface of the side surface  56   b  of the cover member  56 . In addition, the side surface  56   b  of the cover member  56  is formed such that the resin-made long body  51  passing through the passage  56   a  is guided to an outlet of the pipe  52  again. 
     Herein, the description will be described about the operation of the pretensioner  3 . As illustrated in  FIG. 2A , in an initial state, the resin-made long body  51  is contained in the pipe  52 . At that time, the tip of the resin-made long body  51  is disposed in a position not to interfere with the driving wheel  4  in the outlet of the pipe  52 . 
     During the emergency such as the collision of the vehicle, the operation gas of high pressure is supplied from the gas generator  53  into the pipe  52 . The operation gas presses the piston  54  to be slid in the pipe  52 . The piston  54  presses the resin-made long body  51  to be moved in the pipe  52 . The resin-made long body  51  extruded from the pipe  52  moves toward the teeth  41  formed in the outer circumference of the driving wheel  4 . As illustrated in  FIG. 2B , the resin-made long body  51  colliding with the teeth  41  is engaged with the teeth  41  while being deformed plastically, and moves along the passage  56   a  while rotating the driving wheel  4 . 
     In this embodiment, the resin-made long body  51  is formed to be shorter than the outer circumferential length of the driving wheel  4 , and thus, finally, the entire length of the resin-made long body  51  is extruded in the passage  56   a.  Further, the resin-made long body  51  is guided to the outlet of the pipe  52  by the side surface  56   b  of the cover member  56 , and enters into the second rotation while being wound around the driving wheel  4  as illustrated in  FIG. 3A . 
     At that time, the piston  54  may also be extruded to the passage  56   a  together with the resin-made long body  51 , and only the piston  54  may stay in the pipe  52  as illustrated in a modification of  FIG. 3B . 
     Herein, a horizontal axis of  FIG. 4  indicates a time (s), and a vertical axis indicates a load (kN) generated in the driving wheel  4 . As indicated by a solid line in  FIG. 4 , in the above-described pretensioner  3 , when the operation starts at a time t1, a certain load is generated in the driving wheel  4 . When the entire amount of the resin-made long body  51  is extruded from the pipe  52  at a time t2, a pressure by the operation gas is not applied any longer, and thus the load which is applied to the driving wheel  4  by the inertial force of the resin-made long body  51  decreases gradually to balance with the tension of the webbing until a time t3. 
     With respect thereto, in the conventional pretensioner in which a portion of the resin-made long body is engaged with the driving wheel to be rotated, and then the resin-made long body collides with the containing part so that the movement stops, the resin-made long body collides with the containing part at the time t2 as indicated by an one-dot chain line of  FIG. 4 , so that the movement of the resin-made long body stops directly, and thus the load generated in the driving wheel  4  is also reduced directly. 
     Therefore, as illustrated in  FIG. 4 , in the pretensioner  3  according to this embodiment, the driving wheel  4  can be rotated over a time longer than that in the conventional pretensioner, so as to increase a rotating amount of the driving wheel  4 . 
     That is, in the above-described pretensioner  3  and retractor  1  according to this embodiment, the driving wheel  4  is configured to be rotated while the resin-made long body  51  is wound around the driving wheel  4 . Therefore, the driving wheel  4  can be continuously rotated by the inertial force of the resin-made long body  51  until the resin-made long body  51  becomes still, and the maximum winding amount of the webbing can be increased. 
     The resin-made long body  51  is held in the state of being wound around the driving wheel  4 . Therefore, it is unnecessary to secure the space which contains the resin-made long body  51  peeled off from the driving wheel  4 , and it is possible to suppress the enlargement of the pretensioner  3  and the retractor  1 . In addition, it is unnecessary to peel off the resin-made long body  51  wound around the driving wheel  4  from the driving wheel  4 , and thus it is possible to secure the smooth operation of the resin-made long body  51 . 
     Next, a seat belt device according to the embodiment of the present embodiment will be described with reference to  FIG. 5 . Herein,  FIG. 5  is an entire configuration view illustrating the seat belt device according to the embodiment of the present embodiment. Incidentally, in  FIG. 5 , for the convenience of description, the components other than the seat belt device are illustrated by one-dot chain lines. In addition, a seat belt device  100  illustrated in  FIG. 5  indicates a seat belt device which is disposed on a front seat (a driver seat or a passenger seat) of the vehicle. 
     The seat belt device  100  illustrated in  FIG. 5  according to this embodiment includes a webbing W which restrains the occupant, the retractor  1  which performs winding of the webbing W, a guide anchor  101  which is provided in the vehicle body to guide the webbing W, a belt anchor  102  which fixes the webbing W in the vehicle body, a buckle  103  which is disposed on the side surface of the seat S, and a tongue  104  which is disposed in the webbing W. For example, the retractor  1  has the configuration illustrated in  FIG. 1 . 
     For example, the seat S includes a seating part S 1  on which the occupant sits, a backrest portion S 2  which is positioned on the back surface of the occupant, and a headrest S 3  which supports the head of the occupant. For example, the retractor  1  is built in a B pillar T of the vehicle body. In addition, generally, in many cases, the buckle  103  is disposed on the side surface of the seating part S 1 , and the belt anchor  102  is disposed on the lower surface of the seating part S 1 . In addition, in many cases, the guide anchor  101  is disposed in the B pillar T. Further, in the webbing W, the one end is connected with the belt anchor  102 , and the other end is connected with the retractor  1  through the guide anchor  101 . 
     Therefore, in a case where the tongue  104  is fitted into the buckle  103 , the webbing W is drawn from the retractor  1  while sliding along an insertion hole of the guide anchor  101 . In addition, in a case where the occupant fastens the seat belt, or a case where the seat belt is released at the time of getting-off, the webbing W is wound by the effect of the spring unit  12  of the retractor  1  until a certain load is applied. 
     The present embodiment is not limited to the above-described embodiment. For example, the present embodiment may be applied to a seat belt device used in a rear seat of the vehicle, and to a seat belt device used in other vehicles in addition to the vehicle. The present embodiment may be modified variously without departing from the spirit and scope of the embodiment.