JP6661464B2 - Seat belt retractor - Google Patents

Description

  The present invention relates to a seat belt retractor that is mounted on a vehicle and that feeds out and winds up webbing as a seat belt.

  In a seat belt retractor, the webbing is wound in an emergency (when the webbing is suddenly pulled out or when the acceleration of the vehicle changes greatly) in order to restrain the occupant in the seat at the time of a vehicle collision or the like. The retracting rotation of the winding drum is prevented by the lock mechanism.

  Specifically, the seat belt retractor includes a clutch that can rotate relatively coaxially with the winding drum, and a detecting unit that stops the rotation of the clutch in the webbing pull-out direction in an emergency. The above-described lock mechanism operates by the relative rotation between the clutch and the winding drum, the rotation of which is stopped by the detecting means, and prevents the pulling-out rotation of the winding drum. For example, the lock mechanism includes a pawl held by a winding drum and internal teeth formed on a side wall of the housing.

  For example, in Patent Document 1, the lock mechanism prevents the take-up drum from rotating to some extent before the pawl is completely engaged with the internal teeth and the pull-out rotation of the take-up drum is completely prevented. A configured seatbelt retractor is disclosed. The draw-out rotation of the winding drum is prevented to some extent because the clutch is reversely rotated in the webbing winding direction using the self-locking movement of the pawl. The self-locking means that after the pawl starts engaging with the internal teeth, the pawl is guided to the fully engaged position by the shape of the internal teeth.

  In the seat belt retractor disclosed in Patent Literature 1, the webbing can be freely pulled out until the take-up rotation of the winding drum is prevented to some extent, but the webbing can be pulled out after the draw-out rotation of the winding drum is prevented to some extent. The pawl will not completely engage with the internal teeth unless it is pulled out with very strong force. This strong force is assumed to be a load due to the occupant moving forward of the vehicle in an emergency. When the take-up drum further rotates in the webbing pull-out direction from the intermediate restrained state (a state in which the pull-out rotation has been prevented to some extent) by the strong force, the clutch reversely rotates, and the rotation of the clutch in the webbing pull-out direction is stopped by the detecting means. Is released. Therefore, the webbing can be wound up simply by rewinding the webbing.

JP-A-5-246303

  By the way, when the occupant releases the seat belt and rewinds the entire amount of the webbing, the above-described detection means is operated by inertia force or the like, and the rotation of the clutch in the webbing withdrawing direction is stopped by the detection means. A maintained end lock may occur. As the detecting means, a webbing sensor for stopping rotation of the clutch in the webbing withdrawal direction when the webbing is suddenly pulled out, and a vehicle for stopping the rotation of the clutch in the webbing withdrawal direction when the vehicle acceleration significantly changes. There is a sensor, and the end lock is generated by either the webbing sensor or the vehicle sensor.

  In order to release such end lock, the clutch is rotated in the webbing winding direction in the reverse direction, and rotation of the clutch in the webbing withdrawing direction by the detection means is stopped (for example, in the case of a vehicle sensor, the clutch and the vehicle sensor are connected to each other). Engagement) must be released. In the seat belt retractor disclosed in Patent Document 1, the webbing can be freely pulled out until the take-up rotation of the winding drum is prevented to some extent, but the webbing is completely stopped after the draw-out rotation of the winding drum is prevented to some extent. In order to draw out the webbing, a very strong force is required as described above. For this reason, it may be difficult to release the end lock depending on a weak occupant.

  Therefore, an object of the present invention is to enable the end lock to be easily released.

  In order to solve the above problem, the retractor for a seat belt of the present invention includes a winding drum around which webbing is wound, and normally rotates integrally with the winding drum, and coaxially with the winding drum in an emergency. A clutch that rotates relatively, a detecting unit that stops rotation of the clutch in the webbing pull-out direction in an emergency, and the winding that is operated by the relative rotation of the clutch and the winding drum stopped by the detecting unit. A lock mechanism for preventing pulling rotation of the take-up drum; and a spring for biasing the clutch against the take-up drum. In a normal state, the clutch biasing direction of the spring is the webbing pull-out direction, and As the mechanism operates, the clutch biasing direction of the spring gradually approaches the radial direction of the winding drum, and the lock mechanism moves the winding drum. Clutch biasing direction of the spring is the radial direction of the winding drum when the blocking drawer rotation, characterized in that.

  Here, "become radial" means not only when the spring biasing direction of the spring is completely parallel to the radial direction but also when it is substantially parallel (for example, when the angle difference between those directions is 5 degrees). Degrees (more preferably 2 degrees).

  According to the above configuration, when the end lock occurs, if the webbing is pulled out until the pulling-out rotation of the winding drum is stopped, the spring biasing direction becomes the radial direction of the winding drum. Thereby, the frictional force with respect to the relative rotation between the clutch and the winding drum increases. Therefore, if the webbing is released or loosened from this state, the clutch follows the rotation of the winding drum and rotates in the webbing winding direction due to the frictional force between the clutch and the winding drum. As a result, the stop of the rotation of the clutch in the webbing pull-out direction by the detecting means is released. That is, the end lock is released only by pulling out and rewinding the webbing to the limit where the webbing can be freely pulled out. Therefore, the end lock can be easily released.

  For example, the clutch has a first connecting portion to which one end of the spring is connected, the winding drum has a second connecting portion to which the other end of the spring is connected, and the lock mechanism is The first connecting portion and the second connecting portion may be arranged in a radial direction of the winding drum when the rotation of the winding drum is prevented.

  The lock mechanism includes a pawl held by the winding drum and internal teeth formed on a side wall of the housing, and controls the pull-out rotation of the winding drum until the pawl is completely engaged with the internal teeth. Alternatively, the pull-out rotation of the winding drum may be prevented when the pawl is completely engaged with the internal teeth. According to this configuration, a large angle range in which the webbing can be freely pulled out can be secured.

  The clutch has a guide surface for operating the pawl, and when rewinding the webbing after the pull-out rotation of the winding drum is prevented, the pawl pushes the guide surface to rewind the webbing. The rotation of the clutch with respect to the take-up rotation of the take-up drum may be delayed or the clutch may rotate in the webbing pull-out direction, and the spring biasing direction of the spring may return from the radial direction of the take-up drum to the webbing pull-out direction. According to this configuration, it is possible to return the biasing direction of the spring from the radial direction of the winding drum to the webbing withdrawing direction by utilizing the operation of the pawl pressing the guide surface. Then, when the spring biasing direction of the spring returns to the webbing pull-out direction, the clutch returns to the initial state.

  According to the present invention, the end lock can be easily released.

It is a sectional view of a seat belt retractor concerning one embodiment of the present invention. FIG. 2 is an exploded perspective view of the seat belt retractor shown in FIG. 1. FIG. 2 is a side view of the seatbelt retractor shown in FIG. 1 with a mechanism cover removed. It is an exploded perspective view of a winding spring unit. It is a perspective view of a winding drum unit. It is a perspective view of a winding drum and a pawl. FIG. 3 is a perspective view of a clutch, a locking arm, a sensor spring, and a return spring. It is an exploded perspective view of a mechanism cover unit. (A)-(c) is a figure explaining the lock operation by a webbing sensor. (A)-(c) is a figure explaining the lock operation by a webbing sensor. (A)-(c) is a figure explaining the unlocking operation with respect to a webbing sensor. (A) And (b) is a figure explaining unlocking operation with respect to a webbing sensor. (A)-(c) is a figure explaining the lock operation by a vehicle sensor. (A)-(c) is a figure explaining the lock operation by a vehicle sensor. (A)-(c) is a figure explaining the lock release operation with respect to a vehicle sensor. (A) And (b) is a figure explaining unlocking operation with respect to a vehicle sensor.

  1 and 2 show a seat belt retractor 1 according to an embodiment of the present invention. The seatbelt retractor 1 is mounted on a vehicle and feeds out and winds up a webbing 10 as a seatbelt. Specifically, as shown in FIG. 2, the seat belt retractor 1 includes a housing 2, a winding drum unit 1A, a winding spring unit 1B, and a mechanism cover unit 1C.

  Hereinafter, for convenience of description, the axial direction of the winding drum unit 1A is referred to as the left-right direction (in particular, the winding spring unit 1B side is the right side, and the mechanism cover unit 1C side is the left side), and the upper left of FIG. The direction is called the front, and the opposite side is called the back.

  FIG. 3 is a left side view of the seat belt retractor 1 with a mechanism cover 9 described below removed. In FIG. 3, the clockwise direction is the webbing winding direction, and the counterclockwise direction is the webbing pull-out direction.

  As shown in FIG. 2, the housing 2 is a member having a U-shaped cross section that opens forward. Specifically, the housing 2 includes a first side wall 21 and a second side wall 22 facing each other in the left-right direction, a lower rear wall 23 connecting the lower rear portions of the first side wall 21 and the second side wall 22 to each other, An upper rear wall 24 that connects the upper rear portions of the first side wall 21 and the second side wall 22 is included. The protector 11 inserted into the webbing 10 is attached to the upper rear wall 24. A band-shaped tie bar 12 extending in the left-right direction is attached to a front upper portion of the first side wall 21 and a front upper portion of the second side wall 22.

  The winding drum unit 1A includes a winding drum 4 that penetrates the first side wall 21 and the second side wall 22 of the housing 2. The first side wall 21 and the second side wall 22 are provided with drum insertion holes 21a and 22a, respectively, and the winding drum 4 is inserted into these drum insertion holes 21a and 22a.

  The first inner teeth 25 (corresponding to the inner teeth of the present invention) are formed on the inner peripheral surface of the drum insertion hole 21 a provided in the first side wall 21 over the entire circumference. The first side wall 21 also has an opening 26 for a vehicle sensor 7 (see FIG. 3) described later.

  As shown in FIG. 6, the winding drum 4 has one end of the webbing 10 fixed and a drum body 41 around which the webbing 10 is wound, and a drum body 41 located on the left side of the drum body 41 and larger than the drum body 41. A first end 42 having a diameter and a second end 43 located on the right side of the drum main body 41 and having a larger diameter than the drum main body 41 are included. The first end 42 has a relatively thick disk shape, and the first shaft 44 projects leftward from the center of the first end 42. The second end 43 has a disc shape thinner than the first end 42, and a second shaft (not shown) projects rightward from the center of the second end.

  As shown in FIG. 4, the take-up spring unit 1 </ b> B includes a spring seat 31 penetrated through the second shaft of the take-up drum 4 and a spring shaft 32 fixed to the second shaft of the take-up drum 4. . The take-up spring unit 1B includes a take-up spring 33 and a spring case 34 that houses the take-up spring 33. The inner end of the take-up spring 33 is fixed to the spring shaft 32, and the outer end of the take-up spring 33 is fixed to a spring case 34. The spring seat 31 is fitted inside the spring case 34, and the spring case 34 is attached to the second side wall 22 of the housing 2. The take-up spring unit 1 </ b> B urges the take-up drum 4 in the webbing take-up direction by the spring force of the take-up spring 33 when the second shaft portion of the take-up drum 4 is fixed to the spring shaft 32. Further, by attaching the base end of the second shaft portion of the winding drum 4 to the hole of the spring seat 31, the winding drum unit 1A is rotatably supported.

  Returning to FIG. 2, the first end 42 of the winding drum 4 is disposed in the drum insertion hole 21 a provided in the first side wall 21 of the housing 2, and the second end 43 is connected to the second side wall 22. It is arranged in the provided drum insertion hole 22a. The pawl 8 is held at the first end 42 of the winding drum 4. That is, as shown in FIG. 6, the pawl 8 is inserted into the first end 42 of the winding drum 4, passes through the side of the first shaft 44 from the peripheral surface, and is orthogonal to the first shaft 44. A concave portion 42a that is depressed in the direction is formed.

  As shown in FIG. 6, the pawl 8 has a substantially circular arc shape, and has three engaging claws 82 on the outer peripheral surface thereof corresponding to the first internal teeth 25 provided on the first side wall of the housing 2. Are formed. However, the number of the engagement claws 82 can be changed as appropriate. The pawl 8 is completely engaged with the above-described first internal teeth 25 (that is, the engaging claw 82 is completely engaged with the first internal teeth 25) (see FIG. 10C). It moves between a non-engagement position (see FIG. 9 (a)) which is separated radially inward from the internal teeth 25.

  The pawl 8 has a shaft portion 81 protruding leftward. When the pawl 8 moves between the disengaged position and the engaged position, the shaft portion 81 is guided by a guide hole 53 of the clutch 5 described later. The pawl 8 and the first internal teeth 25 are actuated by the relative rotation between the clutch 5 and the winding drum 4, the rotation of which is stopped by the vehicle sensor 7 or the webbing sensor 6, which will be described later, to prevent the winding drum 4 from rotating. Construct a locking mechanism.

  The winding drum unit 1A includes a clutch 5 attached to the winding drum 4 in addition to the winding drum 4, as shown in FIG. The clutch 5 is inserted through the first shaft portion 44 of the winding drum 4 so that the clutch 5 can rotate relative to the winding drum 4. The clutch 5 normally rotates integrally with the winding drum 4 during normal operation, and relatively rotates coaxially with the winding drum 4 during emergency.

  Specifically, as shown in FIG. 7, the clutch 5 includes a circular plate-shaped main wall 51 orthogonal to the left-right direction and a circular cylindrical peripheral wall 52 surrounding the main wall 51. At the center of the main wall 51, a center hole 5b that fits with the first shaft portion 44 of the winding drum 4 is formed. As shown in FIGS. 5 and 6, a projection 44a is provided on the distal end surface of the first shaft portion 44, and the cap 14 is fixed to the projection 44a. By inserting the cap 14 into the bearing 93 of the mechanism cover 9, the winding drum unit 1A is rotatably supported by the mechanism cover 9.

  The clutch 5 is urged against the winding drum 4 by a return spring 13 (corresponding to the spring of the present invention). The clutch biasing direction of the return spring 13 is normally the webbing pull-out direction. As a result, the clutch 5 is normally maintained in a co-rotating position (see FIG. 3) in which the clutch 5 rotates integrally with the winding drum 4.

  In the present embodiment, the return spring 13 is a substantially Ω-shaped spring. The main wall 51 of the clutch 5 is provided with a first mounting pin 54 (corresponding to a first connecting portion of the present invention) protruding leftward near the peripheral wall 52, and a first end of the winding drum 4. The part 42 is provided with a second mounting pin 45 (see FIG. 6, which corresponds to a second connecting part of the present invention) projecting leftward. An arc-shaped slit 50 (see FIG. 7) extending in the circumferential direction of the winding drum 4 is formed in the main wall 51 of the clutch 5, and the second mounting pin 45 is connected to the first mounting pin through the slit 50. It extends to the same height as 54. In other words, the second mounting pin 45 passes through the clutch 5. Further, both ends of the return spring 13 are connected to the first mounting pin 54 and the second mounting pin 45.

  As shown in FIG. 3, the co-rotation position described above is a position where the second mounting pin 45 is located at the end of the slit 50 on the webbing winding direction side. At this time, the center of the second mounting pin 45 is shifted in the webbing winding direction with respect to a line connecting the center of the first mounting pin 54 and the center of the winding drum 4. The return spring 13 biases the first mounting pin 54 and the second mounting pin 45 in a direction away from each other, and as shown in FIG. 3, the first mounting pin 54 has a biasing force F1 and the second mounting pin 45 has a biasing force F1. Act on the urging force F2. Therefore, in the co-rotation position, the clutch 5 is urged in the webbing pull-out direction with respect to the winding drum 4 by the urging force F1 of the return spring 13.

  On the other hand, when the second mounting pin 45 is located near the end of the slit 50 in the webbing pull-out direction, the center of the second mounting pin 45 is on a line connecting the center of the first mounting pin 54 and the center of the winding drum 4. (See FIG. 10C). In other words, the first mounting pins 54 and the second mounting pins 45 are arranged in the radial direction of the winding drum 4. Therefore, when the clutch 5 is rotated relative to the winding drum 4 from the co-rotating position in the webbing winding direction, the clutch biasing direction of the return spring 13 changes from the webbing withdrawing direction to the radial direction of the winding drum 4. .

  Further, the main wall 51 of the clutch 5 is provided with a guide hole 53 through which the shaft portion 81 of the pawl 8 is inserted. The guide hole 53 extends while bending in a direction inclined with respect to the radial direction and the circumferential direction of the winding drum 4 from the radially inner inner end to the radially outer end. Both side surfaces of the guide hole 53 are guide surfaces for operating the pawl 8. More specifically, the side surface of the guide hole 53 in the webbing pull-out direction is a first guide surface 53a (corresponding to the guide surface of the present invention) for pawl 8 advancement, and the side surface of the guide hole 53 in the webbing take-up direction is retracted by the pawl 8. Second guide surface 53b. As shown in FIG. 3, when the clutch 5 is in the co-rotating position, the shaft portion 81 is located at the inner end of the guide hole 53, and the pawl 8 is formed on the first inner wall formed on the first side wall 21 of the housing 2. It is located at a disengaged position that is separated from the teeth 25. When the clutch 5 rotates relative to the winding drum 4 in the webbing winding direction from the co-rotating position, the shaft portion 81 is pushed by the first guide surface 53a of the guide hole 53, and the pawl 8 is engaged from the disengaged position. Move toward the position. On the other hand, when the clutch 5 is rotated relative to the winding drum 4 in the webbing withdrawal direction from the state where the pawl 8 is located at the engagement position, the shaft portion 81 is pushed by the second guide surface 53 b of the guide hole 53 and 8 moves toward the disengaged position. That is, the clutch 5 rotates in conjunction with the pawl 8 in a range between a position where the pawl 8 is at the engaged position and a co-rotating position where the pawl 8 is at the disengaged position.

  As shown in FIG. 8, the above-described mechanism cover unit 1C includes a mechanism cover 9 and a vehicle sensor 7 (corresponding to detection means of the present invention). The mechanism cover 9 is attached to the first side wall 21 of the housing 2 so as to cover the clutch 5 and the vehicle sensor 7.

  The vehicle sensor 7 stops the rotation of the clutch 5 in the webbing withdrawal direction in the first emergency when the acceleration of the vehicle significantly changes (in this embodiment, when the predetermined value β is exceeded). External teeth 5 a (see FIG. 7) are formed on the entire peripheral wall 52 of the clutch 5. The vehicle sensor 7 includes a spherical weight 72, a holder 71 having a concave portion into which the weight 72 fits, and a lever 73 mounted on the weight 72 and attached to the holder 71 so as to swing vertically. A mortar-shaped slope is formed in the concave portion of the holder 71. When the acceleration of the vehicle exceeds a predetermined value β, the weight 72 moves from the initial position in the concave portion of the holder 71 and rises on the slope, so that the lever 73 swings upward from the initial position and the external teeth of the clutch 5 are moved. 5a. Thus, the rotation of the clutch 5 in the webbing pull-out direction is stopped.

  As shown in FIG. 8, the mechanism cover 9 is formed with a cylindrical portion 92 inserted inside the peripheral wall 52 of the clutch 5. Teeth 91 are formed. On the other hand, the clutch 5 is equipped with a webbing sensor 6 (corresponding to the detecting means of the present invention) as shown in FIGS. The webbing sensor 6 rotates the clutch 5 in the webbing withdrawing direction in the second emergency when the webbing 10 is suddenly withdrawn (in the present embodiment, when the withdrawal acceleration of the webbing 10 exceeds a predetermined value α). To stop.

  Specifically, the webbing sensor 6 includes a locking arm 61 that is swingably attached to the clutch 5 and a sensor spring 64 that biases the locking arm 61. The locking arm 61 has a substantially C shape, and has a first end 62 for engaging with the second internal teeth 91 of the mechanism cover 9 and a second end 63 urged by the sensor spring 64. Have. A swing shaft 55 for the webbing sensor 6 is provided on the main wall 51 of the clutch 5 at a position deviated from the center, and the swing shaft 55 swingably supports a substantially center of the locking arm 61. ing. In addition, a support portion 56 that supports the sensor spring 64 is provided on the main wall 51 of the clutch 5.

  When the second end 63 is urged by the sensor spring 64, the locking arm 61 is moved to a non-engagement position (see FIG. 3) where the first end 62 is separated from the second internal teeth 91 of the mechanism cover 9. Will be maintained. On the other hand, when the pull-out acceleration of the webbing 10 exceeds the predetermined value α, the locking arm 61 causes a rotation delay with respect to the clutch 5 due to the inertial force, and the first end 62 engages with the second internal teeth 91. It swings to the mating position (see FIGS. 9B and 9C).

  The main wall 51 of the clutch 5 is provided with a first stopper 58 and a second stopper 59 for the first end 62 of the locking arm 61 and a third stopper 57 for the second end 63. The first stopper 58 and the third stopper 57 define the above-described non-engagement position (initial position), and the second stopper 59 defines the above-described engagement position.

  The seatbelt retractor 1 is configured to detect an emergency (first emergency or second emergency) of the vehicle by one of the vehicle sensor 7 and the webbing sensor 6. When the webbing 10 is pulled out in a state where the clutch 5 is stopped by one of the sensors, the relative rotation between the winding drum 4 and the clutch 5 occurs, and the rotation of the winding drum 4 in the webbing pulling-out direction (drawing rotation). The pawl 8 (locking mechanism) is operated to prevent it. That is, the start of the operation of the lock mechanism is simultaneously with the start of the relative rotation between the winding drum 4 and the clutch 5. In the present embodiment, the lock mechanism does not prevent the pull-out rotation of the winding drum 4 until the pawl 8 is completely engaged with the first internal teeth 25, and the pawl 8 is completely engaged with the first internal teeth 25. Then, the take-out drum 4 is prevented from rotating.

  The above-described biasing direction of the clutch of the return spring 13 is changed as the clutch 5 and the winding drum 4 whose rotation is stopped by one of the vehicle sensor 7 and the webbing sensor 6 rotate relative to each other, in other words, the pawl 8 (lock mechanism). ), The winding drum 4 gradually approaches in the radial direction, and when the pawl 8 is completely engaged with the first internal teeth 25 and the rotation of the winding drum 4 is stopped, the winding drum is stopped. 4 in the radial direction. Hereinafter, the locking operation by the webbing sensor 6 and the locking operation by the vehicle sensor 7 will be described in detail with reference to FIGS. 9A to 16B.

(Lock operation by webbing sensor)
FIGS. 9A to 10C are diagrams illustrating the locking operation by the webbing sensor 6. FIG. 9A shows an initial state in which the webbing 10 is pulled out by a predetermined amount from the seatbelt retractor 1 and worn by an occupant. In the initial state, the clutch 5 is located at the co-rotating position, the pawl 8 is located at the disengaged position, and the locking arm 61 is located at the disengaged position.

  When the webbing 10 is pulled out from the initial state shown in FIG. 9A at an acceleration greater than the predetermined value α, the locking arm rotates integrally with the winding drum 4 as shown in FIG. When the rotation of the clutch 61 is delayed with respect to the clutch 5 by inertia, the clutch 61 swings to the engagement position. In this state, as the clutch 5 further rotates with the webbing 10 being pulled out, the first end 62 of the locking arm 61 engages with the second internal teeth 91 as shown in FIG. The rotation of the clutch 5 in the webbing pull-out direction is stopped.

  Thereafter, as shown in FIG. 10 (a), when the rotation of the clutch 5 in the webbing pull-out direction is stopped, the winding drum 4 is further rotated in the webbing pull-out direction by pulling out the webbing 10, in other words, the winding drum. When the clutch 5 relatively rotates in the webbing winding direction with respect to the shaft 4, the shaft portion 81 of the pawl 8 is pushed by the first guide surface 53 a of the guide hole 53, and the pawl 8 is shifted from the disengaged position to the engaged position. Move towards.

  As shown in FIG. 10B, after the pawl 8 starts to engage with the first internal teeth 25, even if the shaft portion 81 is not pushed by the first guide surface 53 a, as the take-up drum 4 rotates withdrawal. The first internal teeth 25 guide the engaging claws 82 of the pawl 8 so that the pawl 8 moves further outward (that is, the pawl 8 further bites into the first internal teeth 25) (so-called self-lock). . By this self-lock, the pawl 8 finally moves to the engaging position as shown in FIG. 10C and is completely engaged with the first internal teeth 25.

  As the pull-out rotation of the winding drum 4 proceeds in a state where the rotation of the clutch 5 in the webbing pull-out direction is stopped, the clutch biasing direction of the return spring 13 is changed as shown in FIGS. 10 (a) and 10 (b). It gradually approaches the radial direction of the take-up drum 4. Then, as shown in FIG. 10C, when the pawl 8 is completely engaged with the first internal teeth 25, the clutch biasing direction of the return spring 13 becomes the radial direction of the winding drum 4. In other words, when the pull-out rotation of the winding drum 4 is stopped, the first mounting pins 54 and the second mounting pins 45 are arranged in the radial direction of the winding drum 4. As a result, the clutch 5 is strongly pressed against the first shaft portion 44 of the winding drum 4 by the urging force F1 of the return spring 13, and the frictional force against the relative rotation between the clutch 5 and the winding drum 4 increases.

  FIGS. 11A to 12B are diagrams illustrating the unlocking operation when the webbing 10 is rewound after the pull-out rotation of the winding drum 4 is stopped. When the webbing 10 is released or loosened from the locked state shown in FIG. 10C, the urging force of the winding spring 33 always acting on the winding drum 4 causes the webbing 10 to be shown in FIGS. 11A and 11B. Thus, the winding drum 4 rotates in the webbing winding direction. In the locked state shown in FIG. 10C, the frictional force between the clutch 5 and the winding drum 4 is increased, so that the frictional force between the clutch 5 and the winding drum 4 causes the clutch 5 to rotate. Rotates in the webbing winding direction following the rotation of. As a result, the engagement between the first end portion 62 of the locking arm 61 and the second internal teeth 91 of the mechanism cover 9 is released, and the locking arm 61 is biased by the urging force of the sensor spring 64 as shown in FIG. Swing to the disengaged position.

  Further, when the winding drum 4 rotates in the webbing winding direction, as shown in FIG. 11C, the pawl 8 is pushed by the first internal teeth 25 and moves toward the non-engagement position. Accordingly, the shaft portion 81 of the pawl 8 pushes the first guide surface 53a of the guide hole 53 of the clutch 5, and the clutch 5 rotates relative to the winding drum 4 in the webbing pull-out direction. In the present embodiment, the clutch 5 rotates in the webbing pull-out direction. However, the rotation of the clutch 5 in the webbing winding direction may be delayed with respect to the winding rotation of the winding drum 4.

  Due to the relative rotation between the clutch 5 and the winding drum 4, as shown in FIG. 11C, the clutch biasing direction of the return spring 13 returns from the radial direction of the winding drum 4 to the webbing withdrawing direction. As a result, the biasing force F1 of the return spring 13 causes the clutch 5 to rotate in the webbing pull-out direction to the co-rotating position shown in FIG.

  After the biasing direction of the return spring 13 returns to the webbing pull-out direction, even if the winding drum 4 does not rotate in the webbing winding direction from the position shown in FIG. Due to the urging force F1 in the pulling-out direction, the web drum 4 is quickly rotated relative to the winding drum 4 in the webbing pulling-out direction. Thereby, the shaft portion 81 of the pawl 8 is guided by the second guide surface 53b of the guide hole 53 by the relative rotation of the clutch 5 and quickly moves toward the non-engagement position, as shown in FIG. Thus, the pawl 8 returns to the disengaged position and the clutch 5 returns to the co-rotating position. Therefore, as shown in FIG. 12B, the webbing 10 can be pulled out without rotating the winding drum 4 in the webbing winding direction until returning to the position in FIG. 9B before the locking operation is started. The lock is released and the webbing 10 can be pulled out (the lock mechanism is released).

  In the state where the clutch biasing direction of the return spring 13 returns to the webbing pull-out direction in FIG. 11C, the tip of the engaging claw 82 of the pawl 8 has a diameter larger than the diameter of the tip of the first internal teeth 25. It is located outside in the direction. That is, when the pawl 8 is pushed by the first internal teeth 25 and moves toward the disengaged position, the tip of the engaging claw 82 of the pawl 8 moves to the position of the diameter of the tip of the first internal teeth 25. In other words, while the take-up drum 4 rotates in the webbing take-up direction, the clutch 5 can be rotated in the webbing take-out direction while the take-up drum 4 rotates in the webbing take-out direction. I'm going back.

(Lock operation by vehicle sensor)
FIGS. 13A to 14C are diagrams illustrating the locking operation by the vehicle sensor 7. FIG. 13A shows an initial state similar to FIG. 9A.

  When the acceleration of the vehicle exceeds the predetermined value β from the initial state shown in FIG. 13A, the weight 72 moves from the initial position in the concave portion of the holder 71 to form a slope as shown in FIG. As a result, the lever 73 of the vehicle sensor 7 swings upward. In this state, as shown in FIG. 13 (c), when the webbing 10 is pulled out and the clutch 5 rotates integrally with the winding drum 4, the lever 73 engages with the external teeth 5a of the clutch 5, and the webbing of the clutch 5 The rotation in the withdrawal direction is stopped. In FIG. 13C, the weight 72 returns to the initial position in the concave portion of the holder 71 because the acceleration of the vehicle becomes smaller than the predetermined value β, but the lever 73 engages with the external teeth 5 a of the clutch 5. Therefore, it is kept swinging upward.

  Thereafter, as shown in FIG. 14A, the winding drum 4 further rotates while the rotation of the clutch 5 in the webbing withdrawing direction is stopped, in other words, the clutch 5 is wound around the winding drum 4 by the webbing winding. By the relative rotation in the taking direction, the shaft portion 81 of the pawl 8 is pushed by the first guide surface 53a of the guide hole 53, and the pawl 8 moves from the non-engaged position to the engaged position. The subsequent engagement of the pawl 8 with the first internal teeth 25 and the change in the biasing direction of the return spring 13 with the rotation of the take-up drum 4 shown in FIGS. This is the same as the case of the lock operation.

  FIGS. 15A to 16B are views for explaining the unlocking operation when the webbing 10 is rewound after the pull-out rotation of the winding drum 4 is stopped. When the webbing 10 is released or loosened from the locked state shown in FIG. 14C, the urging force of the winding spring 33 that always acts on the winding drum 4 causes the webbing 10 to be shown in FIGS. 15A and 15B. Thus, the winding drum 4 rotates in the webbing winding direction. In the locked state shown in FIG. 14C, the frictional force between the clutch 5 and the winding drum 4 is increased, so that the clutch 5 is moved by the frictional force between the clutch 5 and the winding drum 4. It rotates in the webbing winding direction following the rotation. Thus, the engagement between the lever 73 of the vehicle sensor 7 and the external teeth 5a of the clutch 5 is released, and the lever 73 swings downward and returns to the initial position. The subsequent rotation of the winding drum 4 in the webbing winding direction and the change in the biasing direction of the return spring 13 shown in FIGS. 15C to 16B are different from those in the case of the unlocking operation on the webbing sensor 6. The same is true.

(Release of end lock)
Due to the sudden stop of the winding drum 4 when the entire amount of the webbing 10 is wound, the locking arm 61 further rotates by inertia, and then the winding drum 4 slightly reverses due to the reaction force, and the first end of the locking arm 61 is rotated. When the portion 62 engages with the second internal teeth 91 of the mechanism cover 9 to generate an end lock, the state shown in FIG. Therefore, if the webbing 10 is pulled out from this state until the pulling-out rotation of the winding drum 4 is stopped as described above, and the webbing 10 is freed or loosened, the end lock can be released.

  More specifically, in the state shown in FIG. 9C, the first end 62 of the locking arm 61 is engaged with the second internal teeth 91, and the clutch 5 rotates together with the urging force F1 of the return spring 13. Maintained in position. If the webbing 10 is pulled out from this state, the winding drum 4 rotates in the webbing pulling-out direction against the urging force F1 of the return spring 13. Further, if the webbing 10 is pulled out until the pawl 8 is completely engaged with the first internal teeth 25, the clutch biasing direction of the return spring 13 becomes the radial direction of the winding drum 4. Thereby, the frictional force with respect to the relative rotation between the clutch 5 and the winding drum 4 increases. Therefore, if the webbing 10 is released or loosened from this state, the frictional force between the clutch 5 and the winding drum 4 causes the clutch 5 to follow the rotation of the winding drum 4 and rotate in the webbing winding direction. As a result, the engagement between the first end portion 62 of the locking arm 61 and the second internal teeth 91 is released, and the locking arm 61 swings to the non-engagement position by the urging force of the sensor spring 64. That is, the end lock is released only by pulling out and rewinding the webbing 10 to the limit where the webbing 10 can be freely pulled out.

  With respect to the vehicle sensor 7, the lever 73 swings upward due to an abrupt impact when the winding drum 4 stops when the entire amount of the webbing 10 is wound, and then the winding drum 4 is slightly reversed by the reaction force. Then, when the lever 73 is engaged with the external teeth 5a of the clutch 5 and the end lock occurs, the state shown in FIG. Therefore, the end lock can be released by pulling out the webbing 10 from this state until the webbing 10 is pulled out until the pulling-out rotation of the winding drum 4 is stopped, and then freeing or loosening the webbing 10 as described above. The details are the same as in the case of the webbing sensor 6, and the description thereof is omitted.

  As described above, in the seat belt retractor 1 of the present embodiment, when the end lock occurs, the end lock is released only by pulling out and rewinding the webbing 10 to the limit where the webbing 10 can be freely pulled out. Therefore, the end lock can be easily released.

  Moreover, in the present embodiment, the rotation of the winding drum 4 is not prevented until the pawl 8 is completely engaged with the first internal teeth 25, so that a large angle range in which the webbing 10 can be freely pulled out can be ensured.

  On the other hand, when the webbing 10 is rewound, the operation of the pawl 8 pressing the first guide surface 53a of the guide hole 53 is used to return the biasing direction of the return spring 13 from the webbing winding direction to the webbing pullout direction. be able to.

<Modification>
The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the present invention.

  For example, the return spring 13 does not necessarily have to be a substantially Ω-shaped spring, but may be another spring such as a compression coil spring.

  Similar to the prior art, the locking mechanism prevents the take-up drum 4 from rotating to some extent before the pawl 8 is completely engaged with the first internal teeth 25 and the pull-out rotation of the winding drum 4 is completely prevented. May be blocked. In this case, if the retractor 1 for the seat belt is configured such that the biasing direction of the return spring 13 is the radial direction of the winding drum 4 when the lock mechanism prevents the winding rotation of the winding drum 4 to some extent. Good.

DESCRIPTION OF SYMBOLS 1 Retractor for seat belt 10 Webbing 13 Return spring 2 Housing 21 1st side wall 22 2nd side wall 25 1st internal gear 4 Winding drum 45 2nd mounting pin (2nd connection part)
5 Clutch 54 1st mounting pin (1st connection part)
6 Webbing sensor (detection means)
7 Vehicle sensor (detection means)
8 Paul

Claims (4)

A winding drum around which webbing is wound,
A clutch that normally rotates integrally with the winding drum, and that relatively rotates coaxially with the winding drum in an emergency;
Detecting means for stopping rotation of the clutch in the webbing withdrawal direction in an emergency;
A lock mechanism that operates by the relative rotation between the clutch and the winding drum, the rotation of which is stopped by the detection unit, and that prevents the pull-out rotation of the winding drum;
A spring for urging the clutch against the winding drum,
Normally, the clutch urging direction of the spring is the webbing pull-out direction, and as the lock mechanism operates, the clutch urging direction of the spring gradually approaches the radial direction of the winding drum, and the lock mechanism A retractor for a seat belt, wherein when the pull-out rotation of the take-up drum is stopped, the biasing direction of the spring is in the radial direction of the take-up drum. The clutch has a first connection portion to which one end of the spring is connected,
The winding drum has a second connecting portion to which the other end of the spring is connected,
The retractor for a seat belt according to claim 1, wherein the first connecting portion and the second connecting portion are arranged in a radial direction of the winding drum when the lock mechanism prevents the take-up drum from rotating. .   The lock mechanism includes a pawl held by the winding drum and internal teeth formed on a side wall of the housing, and controls the pull-out rotation of the winding drum until the pawl is completely engaged with the internal teeth. The retractor for a seat belt according to claim 1, wherein the retracting rotation of the winding drum is prevented when the pawl is completely engaged with the internal teeth without blocking. The clutch has a guide surface for operating the pawl,
When the webbing is rewound after the pull-out rotation of the winding drum is stopped, the rotation of the clutch relative to the winding rotation of the winding drum is delayed by pressing the guide surface by the pawl, The retractor for a seat belt according to claim 3, wherein the spring rotates in a webbing pull-out direction, and a clutch urging direction of the spring returns from a radial direction of the winding drum to a webbing pull-out direction.

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