Patent Publication Number: US-2020282947-A1

Title: Webbing take-up device

Description:
TECHNICAL FIELD 
     The present invention relates to a webbing take-up device in which a webbing worn by an occupant is taken up on a spool. 
     BACKGROUND ART 
     In the webbing take-up device disclosed in JP-A No. 2014-136451, a webbing is taken up on a spool, and in a case in which the angular acceleration of rotation of the spool in a pull-out direction is equal to or greater than a predetermined angular acceleration, a W-pawl of a lock mechanism is activated and the lock mechanism locks the rotation of the spool. 
     Here, in this webbing take-up device, when the radius of the webbing taken up on the spool fluctuates in a case in which the acceleration with which the webbing is pulled out from the spool is the same, the angular acceleration of rotation of the spool in the pull-out direction fluctuates. 
     SUMMARY OF INVENTION 
     Technical Problem 
     In consideration of the above circumstances, it is an object of the present invention to obtain a webbing take-up device that can lock the rotation of the spool on based on the acceleration with which the webbing is pulled out from the spool. 
     Solution to Problem 
     A webbing take-up device of a first aspect of the invention includes: a spool on which webbing worn by an occupant is taken up and which is rotated in a pull-out direction when the webbing is pulled out; and a lock mechanism that locks rotation of the spool in a case in which an acceleration with which the webbing is pulled out from the spool is equal to or greater than a predetermined acceleration. 
     A webbing take-up device of a second aspect of the invention is the webbing take-up device of the first aspect of the invention, wherein the acceleration with which the webbing is pulled out from the spool is detected based on a radius of the webbing taken up on the spool and an angular acceleration of rotation of the spool in the pull-out direction. 
     A webbing take-up device of a third aspect of the invention is the webbing take-up device of the first aspect or the second aspect of the invention, further including a detector that detects an angle of rotation of the spool, whereby at least one of a radius of the webbing taken up on the spool or an angular acceleration of rotation of the spool in the pull-out direction is detected. 
     A webbing take-up device of a fourth aspect of the invention is the webbing take-up device of any one of the first aspect to the third aspect of the invention, further including a detector that detects light from at least one of the spool or the webbing, whereby at least one of a radius of the webbing taken up on the spool, an angular acceleration of rotation of the spool in the pull-out direction, or the acceleration with which the webbing is pulled out from the spool is detected. 
     Advantageous Effects of Invention 
     In the webbing take-up device of the first aspect of the invention, the webbing worn by the occupant is taken up on the spool, and the spool is rotated in the pull-out direction when the webbing is pulled out from the spool. 
     Here, in a case in which the acceleration with which the webbing is pulled out from the spool is equal to or greater than the predetermined acceleration, the lock mechanism locks the rotation of the spool. For this reason, the rotation of the spool can be locked on based on the acceleration with which the webbing is pulled out from the spool. 
     In the webbing take-up device of the second aspect of the invention, the acceleration with which the webbing is pulled out from the spool is detected on based on the radius of the webbing taken up on the spool and the angular acceleration of rotation of the spool in the pull-out direction. For this reason, the acceleration with which the webbing is pulled out from the spool can be easily detected. 
     In the webbing take-up device of the third aspect of the invention, the detector detects the angle of rotation of the spool, whereby at least one of the radius of the webbing taken up on the spool or the angular acceleration of rotation of the spool in the pull-out direction is detected. For this reason, at least one of the radius of the webbing taken up on the spool or the angular acceleration of rotation of the spool in the pull-out direction can be easily detected. 
     In the webbing take-up device of the fourth aspect of the invention, the detector detects light from at least one of the spool or the webbing, whereby at least one of the radius of the webbing taken up on the spool, the angular acceleration of rotation of the spool in the pull-out direction, or the acceleration with which the webbing is pulled out from the spool is detected. For this reason, at least one of the radius of the webbing taken up on the spool, the angular acceleration of rotation of the spool in the pull-out direction, or the acceleration with which the webbing is pulled out from the spool can be easily detected. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an exploded perspective view, seen obliquely from the front and left, showing a webbing take-up device pertaining to an embodiment of the invention. 
         FIG. 2  is a sectional view, seen from the left, showing the webbing take-up device pertaining to the embodiment of the invention. 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     In  FIG. 1  a webbing take-up device  10  pertaining to an embodiment of the invention is shown in an exploded perspective view seen obliquely from the front and left, and in  FIG. 2  the webbing take-up device  10  is shown in a sectional view seen from the left. It will be noted that in the drawings arrow FR indicates the front direction of the webbing take-up device  10 , arrow RH indicates the right direction of the webbing take-up device  10 , and arrow UP indicates the up direction of the webbing take-up device  10 . 
     As shown in  FIG. 1  and  FIG. 2 , the webbing take-up device  10  pertaining to the embodiment is equipped with a U-shaped plate-like frame  12 , and the frame  12  is provided with a back plate  12 A on the rear side, a leg plate  12 B on the left side, and a leg plate  12 C on the right side. The back plate  12 A is anchored to a vehicle body, whereby the webbing take-up device  10  is anchored to the vehicle body. A through hole  14  and a through hole  16  are formed through the leg plate  12 B and the leg plate  12 C, respectively, and the through hole  14  and the through hole  16  are coaxially disposed. 
     A substantially cylindrical spool  18  is rotatably supported between the through hole  14  in the leg plate  12 B and the through hole  16  in the leg plate  12 C, and a base end portion of a long band-like webbing  20  is anchored to the spool  18 . The webbing  20  is taken up on the spool  18  when the spool  18  is rotated in a take-up direction (one direction about its axis; the direction of arrow A in  FIG. 1  and  FIG. 2 ), and the spool  18  is rotated in a pull-out direction (the other direction about its axis; the direction of arrow B in  FIG. 1  and  FIG. 2 ) when the webbing  20  is pulled out from the spool  18 . The webbing  20  is pulled out upward from the spool  18 , and the webbing  20  is configured to be wearable by an occupant of the vehicle. 
     A substantially disc-shaped lock gear  22  serving as a lock counterpart component is coaxially provided on the left end portion of the spool  18 , and the lock gear  22  projects on the left side of the leg plate  12 B via the through hole  14  in the leg plate  12 B. The lock gear  22  is configured to be integrally rotatable with the other portion of the spool  18 , and ratchet teeth  22 A are formed along the entire circumference of the lock gear  22 . 
     An angle-of-rotation sensor  24  serving as a detector is provided in, for example, the frame  12 , and the angle-of-rotation sensor  24  detects the angle of rotation of the spool  18 . For this reason, the angle-of-rotation sensor  24  is configured to be able to detect the direction of rotation, the angular velocity of rotation, and the angular acceleration of rotation (in particular, an angular acceleration a of rotation in the pull-out direction shown in  FIG. 2 ) of the spool  18 , the amount of the webbing  20  taken up on the spool  18 , the amount of the webbing  20  pulled out from the spool  18 , and a radius r of the webbing  20  taken up on the spool  18  (the radius of the spool  18  and the webbing  20  at the position where the webbing  20  is pulled out from the spool  18 ; see  FIG. 2 ), and is configured to be able to detect the acceleration of the webbing  20  (in particular, an acceleration a with which the webbing  20  is pulled out from the spool  18 , shown in  FIG. 2 ). It will be noted that in  FIG. 2  reference sign O denotes the central axis of rotation of the spool  18 . 
     A biasing mechanism (not shown in the drawings) is provided on the right side of the leg plate  12 C, and the biasing mechanism is mechanically connected to the spool  18 . The biasing mechanism biases the spool  18  in the take-up direction, and when the webbing  20  is being worn by the occupant, the webbing  20  is acted upon by a force that takes it up on the spool  18  because of the biasing force of the biasing mechanism, whereby slack in the webbing  20  is eliminated. 
     An electric lock mechanism  26  is provided on the left side of the leg plate  12 B. The lock mechanism  26  is provided with a plate-like lock pawl  28  serving as a lock component, and the lock pawl  28  is supported at its base end portion so as to be pivotable in a predetermined range on the left side of the leg plate  12 B. Lock teeth  28 A are formed on a distal end portion of the lock pawl  28 , and the lock teeth  28 A are spaced apart, on the radial direction outer side of the lock gear  22 , from the ratchet teeth  22 A of the lock gear  22 . 
     The lock mechanism  26  is provided with an activation device  30 , and when the activation device  30  is electrically activated, the lock pawl  28  is pivoted toward the lock gear  22  (inward in the radial direction of the lock gear  22 ) by biasing force to cause the lock teeth  28 A of the lock pawl  28  to mesh with the ratchet teeth  22 A of the lock gear  22 . For this reason, rotation of the lock gear  22  in the pull-out direction is locked and rotation of the spool  18  in the pull-out direction is locked. 
     It will be noted that when the spool  18  is rotated in the take-up direction in a state in which the lock teeth  28 A of the lock pawl  28  are meshed with the ratchet teeth  22 A of the lock gear  22 , the lock teeth  28 A of the lock pawl  28  are moved by the ratchet teeth  22 A of the ratchet gear  22 , and the lock pawl  28  is pivoted in the opposite direction of the lock gear  22  (outward in the radial direction of the lock gear  22 ) counter to the biasing force of the activation device  30 . For this reason, rotation of the lock gear  22  in the take-up direction is allowed and rotation of the spool  18  in the take-up direction is allowed. 
     The angle-of-rotation sensor  24  and the activation device  30  of the lock mechanism  26  are electrically connected to a control device  32  serving as a control component. 
     Next, the action of the embodiment will be described. 
     In the webbing take-up device  10  with the above configuration, the webbing  20  is pulled out from the spool  18  and worn by the occupant. At this time, the webbing  20  is acted upon by a force that takes it up on the spool  18  because of the biasing force of the biasing mechanism, whereby slack in the webbing  20  is eliminated. 
     At the time of an impact to the vehicle (at the time of an emergency (a predetermined occasion)), the webbing  20  is abruptly pulled by the occupant and the webbing  20  is abruptly pulled out from the spool  18 , whereby the activation device  30  of the lock mechanism  26  is electrically activated by control of the control device  32 . For this reason, the activation device  30  causes the lock pawl  28  to pivot toward the lock gear  22  and causes the lock teeth  28 A of the lock pawl  28  to mesh with the ratchet teeth  22 A of the lock gear  22 , whereby rotation of the lock gear  22  in the pull-out direction is locked and rotation of the spool  18  in the pull-out direction is locked. Because of this, the pulling-out of the webbing  20  from the spool  18  is locked and the occupant is restrained by the webbing  20 . 
     Here, in a case in which the acceleration a with which the webbing  20  is pulled out from the spool  18 , which is based on the radius r of the webbing  20  taken up on the spool  18  and the angular acceleration a of rotation of the spool  18  in the pull-out direction that are detected by the angle-of-rotation sensor  24 , is equal to or greater than a predetermined acceleration, the lock mechanism  26  locks the rotation of the spool  18  in the pull-out direction because of the control of the control device  32 . For this reason, the rotation of the spool  18  in the pull-out direction can be locked on based on the acceleration a with which the webbing  20  is pulled out from the spool  18 , and the occupant can be restrained by the webbing  20 . Because of this, even in a case in which the acceleration a with which the webbing  20  is pulled out from the spool  18  is the same, the activation threshold of the lock mechanism  26  can be inhibited from fluctuating as a result of the radius r of the webbing  20  taken up on the spool  18  fluctuating due to differences in the physique of the occupant and the angular acceleration a of rotation in the pull-out direction from the spool  18  fluctuating, and the occupant restraint performance of the webbing  20  can be inhibited from varying due to the physique of the occupant. 
     Furthermore, the radius r of the webbing  20  taken up on the spool  18  and the angular acceleration a of rotation of the spool  18  in the pull-out direction are detected by the angle-of-rotation sensor  24 , whereby the acceleration a with which the webbing  20  is pulled out from the spool  18  is detected. For this reason, the acceleration a with which the webbing  20  is pulled out from the spool  18  can be easily detected. 
     Moreover, the angle of rotation of the spool  18  is detected by the angle-of-rotation sensor  24 , whereby the radius r of the webbing  20  taken up on the spool  18  and the angular acceleration a of rotation of the spool  18  in the pull-out direction are detected. For this reason, the radius r of the webbing  20  taken up on the spool  18  and the angular acceleration a of rotation of the spool  18  in the pull-out direction can be easily detected. 
     It will be noted that in this embodiment the radius r of the webbing  20  taken up on the spool  18  and the angular acceleration a of rotation of the spool  18  in the pull-out direction are detected by the angle-of-rotation sensor  24 , whereby the acceleration a with which the webbing  20  is pulled out from the spool  18  is detected. However, an optical sensor (e.g., a camera) serving as a detector may also detect light from at least one of the spool  18  or the webbing  20  to thereby detect at least one of the radius r of the webbing  20  taken up on the spool  18 , the angular acceleration a of rotation of the spool  18  in the pull-out direction, or the acceleration a with which the webbing  20  is pulled out from the spool  18 . 
     The disclosure of Japanese Patent Application No. 2017-174818 filed on Sep. 12, 2017, is incorporated in its entirety by reference herein. 
     REFERENCE SIGNS LIST 
     
         
           10  Webbing Take-up Device 
           18  Spool 
           20  Webbing 
           24  Angle-of-rotation Sensor (Detector) 
           26  Lock Mechanism