JP2010052512A - Webbing takeup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve an occupant's comfort while a webbing is mounted. <P>SOLUTION: In this webbing takeup device 10, a worm wheel 24 rotated by a motor 36 is connected to a takeup shaft 12 via a spiral spring 26 of a low torque. The spiral spring 26 energizes the takeup shaft 12 in a direction for negating a relative rotation when the worm wheel 24 relatively rotates to the takeup shaft 12. Thereby, the takeup shaft 12 is normally held at a predetermined neutral position relative to the worm wheel 24 (a position, where the spiral spring 26 is under a natural position). Then, an ECU 48 controls an operation of the motor 36 so as to maintain a condition (a low-torque energizing condition) that the worm wheel 24 relatively rotates in a takeup direction to the takeup shaft 12 from the neutral position by a predetermined angle (for example, 90 degrees). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a webbing take-up device.

Conventional webbing take-up devices include a low-torque return spring (spring spring) that urges the take-up shaft in the webbing take-up direction, and a motor that rotates the take-up shaft in the webbing take-up direction ( For example, see Patent Document 1). In such a webbing take-up device, the webbing attached to the occupant is given tension by a low-torque spring spring, so that the occupant can be prevented from being compressed. In addition, since the shortage of the spring force of the mainspring can be compensated by the driving force of the motor, the webbing can be wound up to the end.
JP 2001-225720 A

  However, in the webbing take-up device as described above, the urging force of the spring spring increases in proportion to the increase in the webbing pull-out amount, so that the tension acting on the webbing is not constant. For this reason, there is room for further improvement in order to improve passenger comfort.

  In view of the above facts, an object of the present invention is to provide a webbing retractor that can improve the comfort of a passenger in a webbing wearing state.

  The webbing take-up device according to the first aspect of the invention is a take-up shaft that is rotated in the take-up direction to take up the occupant restraining webbing and is rotated in the draw-out direction when the webbing is drawn out. A rotating body that is coaxially and relatively rotatable with respect to the winding shaft, a motor that can rotate the rotating body in the winding direction and the drawing direction, the winding shaft, and the rotating body. And a spring that biases the winding shaft in a direction that cancels the relative rotation when the winding shaft rotates relative to the rotating body, and a relative rotation amount of the rotating body with respect to the winding shaft And a control means for adjusting a relative rotation amount of the rotating body with respect to the winding shaft by operating the motor based on a detection result of the relative rotation amount detection means. Was it It is characterized.

  In the webbing take-up device according to the first aspect, the relative rotation amount detection means detects the relative rotation amount of the rotating body with respect to the take-up shaft, and the control means operates the motor based on the detection result. Thereby, the relative rotation amount of the rotating body with respect to the winding shaft is adjusted.

  Here, when the occupant pulls out the webbing to mount the webbing, the winding shaft rotates relative to the rotating body in the pulling direction, and the relative rotation amount of the rotating body with respect to the winding shaft changes. At this time, for example, if the control means operates the motor to rotate the rotating body in the drawing direction so as to cancel this change, the rotating body follows the winding shaft and is rotated in the drawing direction. Thereby, since the increase in the biasing force of the spring due to the relative rotation is suppressed, the occupant can easily pull out the webbing.

  Then, for example, when the occupant is connected to the buckle device by connecting the tongue plate attached to the webbing, the rotation of the winding shaft is stopped when the occupant is in a state of wearing the webbing. At this time, for example, if the control means stops the motor while the rotating body rotates relative to the take-up shaft by a predetermined amount in the take-up direction, the spring is taken up by the take-up shaft regardless of the webbing withdrawal amount. Is urged in the winding direction with a constant urging force. As a result, the webbing can be brought into close contact with the occupant's body with a constant tension. In addition, in this case, the biasing force of the spring acting on the take-up shaft (that is, the tension acting on the webbing) is set low by setting the relative rotation amount (the predetermined amount) of the rotating body with respect to the take-up shaft to be small. be able to. As a result, the comfort of the passenger wearing the webbing can be improved.

  Furthermore, in the above webbing wearing state, for example, if the control means appropriately operates the motor so that the rotating body maintains a state of relative rotation in the winding direction by a predetermined amount with respect to the winding shaft, the occupant takes a posture. Even when the webbing withdrawal amount is changed by changing the tension, the tension acting on the webbing can be made constant. Thereby, a passenger | crew's easiness of movement can be ensured and a passenger | crew's comfort can be improved.

  On the other hand, when the occupant releases the webbing wearing state, the winding shaft rotates relative to the rotating body in the winding direction by the biasing force of the spring, and the relative rotation amount of the rotating body with respect to the winding shaft changes. At this time, for example, if the control means operates the motor to rotate the rotating body in the winding direction, the rotational force of the rotating body is transmitted to the winding shaft via the spring, and the winding shaft moves in the winding direction. It is rotated. Thereby, the webbing can be wound around the winding shaft.

  According to a second aspect of the present invention, there is provided a webbing take-up device that takes up a webbing for restraining an occupant by being rotated in the take-up direction and is rotated in the take-out direction by being pulled out. A rotating body that is coaxially and relatively rotatable with respect to the winding shaft, a motor that can rotate the rotating body in the winding direction and the drawing direction, the winding shaft, and the rotating body. And a spring that biases the winding shaft in a direction that cancels the relative rotation when the winding shaft rotates relative to the rotating body, and a relative rotation amount of the rotating body with respect to the winding shaft Relative rotation amount detection means for detecting the rotation, and by operating the motor based on the detection result of the relative rotation amount detection means, the rotating body rotates relative to the winding shaft by a predetermined amount in the winding direction. Maintained state It is characterized and control means for, further comprising: a.

  In the webbing take-up device according to the second aspect, the relative rotation amount detecting means detects the relative rotation amount of the rotating body with respect to the take-up shaft, and the control means operates the motor based on the detection result. As a result, the state in which the rotating body is relatively rotated in the winding direction by a predetermined amount with respect to the winding shaft is maintained.

  Here, when the occupant pulls out the webbing to mount the webbing, the winding shaft rotates relative to the rotating body in the pulling direction, and the relative rotation amount of the rotating body with respect to the winding shaft changes. For this reason, the control means operates the motor so as to cancel this change, and rotates the rotating body in the pulling-out direction. Thereby, since a rotary body follows a winding axis | shaft and rotates to a drawing-out direction, the increase in the urging | biasing force of the spring by the said relative rotation is suppressed. Therefore, the occupant can easily pull out the webbing.

  Then, for example, when the occupant is connected to the buckle device by connecting the tongue plate attached to the webbing, the rotation of the winding shaft is stopped when the occupant is in a state of wearing the webbing. For this reason, the control means stops the motor in a state in which the rotating body is relatively rotated in the winding direction by a predetermined amount with respect to the winding shaft. In this state, the spring urges the take-up shaft in the take-up direction with a constant urging force regardless of the webbing pull-out amount. As a result, the webbing can be brought into close contact with the occupant's body with a constant tension. In addition, in this case, the biasing force of the spring acting on the take-up shaft (that is, the tension acting on the webbing) is set low by setting the relative rotation amount (the predetermined amount) of the rotating body with respect to the take-up shaft to be small. be able to. As a result, the comfort of the passenger wearing the webbing can be improved.

  Furthermore, even when the webbing pull-out amount changes due to the occupant changing his / her posture in the webbing wearing state, the control means operates the motor so that the relative rotation state of the predetermined amount is maintained. The acting tension can be made constant. Thereby, a passenger | crew's easiness of movement can be ensured and a passenger | crew's comfort can be improved.

  On the other hand, when the occupant releases the webbing wearing state, the winding shaft rotates relative to the rotating body in the winding direction by the biasing force of the spring, and the relative rotation amount of the rotating body with respect to the winding shaft changes. For this reason, the control means operates the motor so as to cancel this change, and rotates the rotating body in the winding direction. The rotational force of the rotating body is transmitted to the take-up shaft via the spring, and the take-up shaft is rotated in the drawing direction. As a result, the webbing is wound around the winding shaft. When the webbing can no longer be taken up, the take-up shaft is stopped, and the control means stops the motor while the rotating body rotates relative to the take-up shaft by a predetermined amount in the take-up direction. Let Thereby, the winding of the webbing is completed.

  A webbing take-up device according to a third aspect of the present invention is the webbing take-up device according to the first or second aspect, wherein the relative rotation amount detecting means is provided on one of the take-up shaft and the rotating body. It has an attached magnetic sensor and a magnet attached to the other of the winding shaft and the rotating body.

  In the webbing take-up device according to claim 3, when the take-up shaft rotates relative to the rotating body, the magnetic sensor attached to one of these rotates the magnetic field magnitude of the magnet attached to the other and Measure the direction. Thereby, since the relative rotation amount of the rotating body with respect to the winding shaft can be detected, the relative rotation amount detection means can be configured simply.

  A webbing take-up device according to a fourth aspect of the present invention is the webbing take-up device according to the first or second aspect, wherein the relative rotation amount detecting means detects a rotation amount of the take-up shaft. It has 1 rotation amount detector and the 2nd rotation amount detector which detects the rotation amount of the said rotary body, It is characterized by the above-mentioned.

  According to a fourth aspect of the present invention, the webbing take-up device is configured to take up the take-up shaft by a difference between the rotation amount of the take-up shaft detected by the first rotation amount detector and the rotation amount of the rotating body detected by the second rotation amount detector. Since the relative rotation amount of the rotating body with respect to the shaft can be detected, the relative rotation amount detection means can have a simple configuration.

  As described above, in the webbing take-up device according to the present invention, it is possible to improve the comfort of the passenger in the webbing wearing state.

<First Embodiment>
FIG. 1 shows a schematic exploded perspective view of a webbing retractor 10 according to a first embodiment of the present invention.

  The webbing take-up device 10 constitutes a vehicle seat belt device, and includes a take-up shaft 12. The winding shaft 12 is formed in a cylindrical shape and is rotatably supported by the frame 14. A base end portion of an occupant restraining webbing 16 formed in a long belt shape is locked to the winding shaft 12, and the winding shaft 12 is rotated around its axis (in the direction of arrow A in FIG. 1, hereinafter). When this direction is rotated in the “winding direction”), the webbing 16 is wound around the outer periphery of the winding shaft 12 from the base end side. On the other hand, if the webbing 16 is pulled from the front end side, the webbing 16 is pulled out while the winding shaft 12 rotates around the axis in the other direction (in the direction of arrow B in FIG. 1) (hereinafter referred to as winding when pulling out the webbing 16). The direction of rotation of the take-up shaft 12 is referred to as “drawing direction”).

  An adapter 18 is connected to one end of the winding shaft 12 in the axial direction outside the frame 14, and a box-shaped base 20 is attached to the side of the frame 14. The adapter 18 is disposed in the base 20 and always rotates integrally with the winding shaft 12.

  In the base 20, a worm wheel 24 as a rotating body and a low torque spring 26 as a spring are arranged. The worm wheel 24 is formed in a bottomed cylindrical shape having an opening on the winding shaft 12 side, and is supported so as to be rotatable with respect to the base 20 while being coaxial and relatively rotatable with respect to the winding shaft 12. Yes.

  On the other hand, the spring spring 26 is housed inside the worm wheel 24, and an inner end portion thereof is locked to the adapter 18 and an outer end portion thereof is locked to the worm wheel 24. When the worm wheel 24 rotates relative to the winding shaft 12, the mainspring 26 urges the winding shaft 12 in a direction that cancels the relative rotation. That is, when the worm wheel 24 rotates relative to the take-up shaft 12 in the take-up direction, the mainspring spring 26 biases the take-up shaft 12 in the take-up direction, and the worm wheel 24 pulls out from the take-up shaft 12. When the relative rotation is performed, the winding shaft 12 is urged in the pull-out direction. For this reason, the winding shaft 12 is normally held at a predetermined neutral position (a position where the mainspring 26 is in a natural state) with respect to the worm wheel 24.

  Further, worm teeth 28 are formed on the outer peripheral portion of the worm wheel 24, and the worm gear 30 is engaged with the worm teeth 28. The worm gear 30 is supported by a shaft 32 that is rotatably supported with respect to the base 20, and a spur gear 34 is attached to one end of the shaft 32 in the axial direction. The spur gear 34 meshes with a spur gear 40 attached to the output shaft 38 of the motor 36.

  The motor 36 is fixed to the base 20 by a stay 42, and the spur gear 34, the spur gear 40 and the like are covered with a cover 44. Thus, when the motor 36 is driven, the driving force is transmitted through the spur gear 40, the spur gear 34, the worm gear 30 and the worm teeth 28, and the worm wheel 24 is rotated.

  In this case, when the output shaft 38 of the motor 36 is rotated forward, the worm wheel 24 is rotated in the winding direction (direction of arrow A in FIG. 1), and when the output shaft 38 of the motor 36 is reversed, the worm wheel 24 is pulled out ( It is rotated in the direction of arrow B in FIG.

  On the other hand, as shown in FIG. 1, the webbing retractor 10 includes a driver 46 and an ECU 48 that constitute control means. The ECU 48 stores a drive control program according to the first embodiment of the present invention. In addition, the motor 36 is electrically connected to a battery 50 mounted on the vehicle via a driver 46, and the current from the battery 50 flows to the motor 36 via the driver 46, so that the motor 36 has a driving force. Thus, the output shaft 38 is configured to rotate forward or reverse. The driver 46 is connected to the ECU 48, and the ECU 48 controls the presence / absence of power supply to the motor 36 via the driver 46 and the direction of supply current.

  Further, an electrical signal is transmitted to the ECU 48 from a magnetic sensor 52 attached to the worm wheel 24. The magnetic sensor 52 corresponds to the magnet 54 attached to the winding shaft 12, detects the magnitude and direction of the magnetic field (magnetic field) generated by the magnet 54, and outputs a predetermined electric signal to the ECU 48. As a result, the ECU 48 detects a relative rotation amount (here, a relative angle) between the winding shaft 12 and the worm wheel 24. Note that signal transmission between the magnetic sensor 52 and the ECU 48 is performed using wireless or flexible wiring.

  Here, in the first embodiment, the ECU 48 is configured to adjust the relative rotation amount of the worm wheel 24 with respect to the winding shaft 12 by operating the motor 36 based on the electric signal from the magnetic sensor 52. ing. Specifically, the ECU 48 rotates the worm wheel 24 relative to the winding shaft 12 from the neutral position in the winding direction by a predetermined angle (for example, 90 degrees) (hereinafter, “low torque biasing state”). The operation of the motor 36 is controlled so as to be maintained. In this low torque urging state, the winding shaft 12 is urged in the winding direction with a low torque by the mainspring 26, and the tension applied to the webbing 16 by the winding shaft 12 is attached to the webbing 16. It is set to such an extent that the occupant is not compressed (the webbing 16 is lightly fitted to the occupant).

  Next, the operation of the first embodiment will be described with reference to the flowchart shown in FIG.

  In the webbing take-up device 10 configured as described above, in the retracted state in which the webbing 16 is taken up by the take-up shaft 12, the take-up shaft 12 is restricted from rotating in the take-up direction by the webbing 16. Further, the ECU 48 stops the motor 36 in a state where the worm wheel 24 is relatively rotated by a predetermined angle in the winding direction from the neutral position with respect to the winding shaft 12 (low torque biasing state). Is biased in the winding direction with low torque by the biasing force of the spring spring 26.

  Here, when the occupant pulls out the webbing 16 to mount the webbing 16, the winding shaft 12 rotates relative to the worm wheel 24 in the pull-out direction. For this reason, the relative angle of the winding shaft 12 with respect to the worm wheel 24 changes, and the magnetic sensor 52 outputs a predetermined electrical signal to the ECU 48. Thus, the ECU 48 detects that the winding shaft 12 has rotated relative to the worm wheel 24 (step 100).

  Next, the ECU 48 determines whether the winding shaft 12 has rotated relative to the worm wheel 24 in the winding direction based on the electrical signal from the magnetic sensor 52 (step 102). Here, since the take-up shaft 12 is rotated relative to the worm wheel 24 in the pull-out direction by pulling out the webbing 16 by the occupant, the ECU 48 denies the above determination and proceeds to step 104.

  In step 104, the ECU 48 reverses the output shaft 38 of the motor 36. As a result, the worm wheel 24 follows the winding shaft 12 and is rotated in the drawing direction. Thereby, since the increase in the urging force of the mainspring spring 26 from the low torque urging state is suppressed, the occupant can easily pull out the webbing 16. When the processing at step 104 is completed, the routine proceeds to the next step 106.

  In step 106, the ECU 48 determines whether or not the low torque biasing state has been secured again based on the electrical signal from the magnetic sensor 52. Only when this determination is affirmed, the routine proceeds to the next step 108 and the output shaft 38 of the motor 36 is stopped.

  For example, when the occupant interrupts the withdrawal of the webbing 16 halfway, the take-up shaft 12 is stopped, so that the ECU 48 causes the worm wheel 24 that follows the take-up shaft 12 to rotate in the pull-out direction. 12, the power supply to the motor 36 is cut off at the time when a position relatively rotated by a predetermined angle in the winding direction from the neutral position (that is, when the low torque urging state is secured again) (step 108). The rotation of the worm wheel 24 is stopped. In this state, a constant low tension is applied to the webbing 16 held by the occupant by the mainspring spring 26 in a low torque biasing state.

  When the processing in step 108 is completed, the ECU 48 returns to step 100 described above and determines whether or not the winding shaft 12 is relatively rotated with respect to the worm wheel 24. For example, when the occupant releases the webbing 16 (when the webbing 16 is not pulled out), the winding shaft 12 rotates relative to the worm wheel 24 in the winding direction by the urging force of the mainspring spring 26. Therefore, the magnetic sensor 52 outputs a predetermined electrical signal to the ECU 48, and the ECU 48 detects the relative rotation of the winding shaft 12 with respect to the worm wheel 24 (step 100).

  Next, the ECU 48 determines whether the winding shaft 12 has rotated relative to the worm wheel 24 in the winding direction based on the electrical signal from the magnetic sensor 52 (step 102). Here, because the winding shaft 12 is relatively rotated in the winding direction with respect to the worm wheel 24 by the urging force of the mainspring 26, the ECU 48 affirms the above determination and proceeds to Step 110.

  In step 110, the ECU 48 causes the output shaft 38 of the motor 36 to rotate normally. Thereby, the worm wheel 24 is rotated in the winding direction. The rotational force of the worm wheel 24 is transmitted to the winding shaft 12 via the mainspring 26, and the winding shaft 12 is rotated in the winding direction. As a result, the webbing 16 is wound and stored on the winding shaft 12. When the processing in step 110 is completed, the process proceeds to next step 112.

  In step 112, the ECU 48 determines whether or not the low torque biasing state has been secured again based on the electrical signal from the magnetic sensor 52. Only when this determination is affirmed, the routine proceeds to the next step 108 and the output shaft 38 of the motor 36 is stopped.

  Here, when the rotation of the winding shaft 12 is stopped by storing the webbing 16, the ECU 48 reaches a position where the worm wheel 24 rotates relative to the winding shaft 12 from the neutral position by a predetermined angle in the winding direction. At that time, the motor 36 is stopped (step 112, step 108).

  On the other hand, when the occupant who has stopped pulling out the webbing 16 as described above pulls out the webbing 16 again, the winding shaft 12 rotates relative to the worm wheel 24 in the pulling-out direction. Therefore, as in the case described above, the ECU 48 performs the processing from step 100 to step 104, whereby the worm wheel 24 follows the winding shaft 12 and rotates in the pulling direction, and the spring spring from the low torque biasing state An increase in the urging force of 26 is suppressed. Thereby, the passenger can easily pull out the webbing 16.

  In the next step 106, as described above, the ECU 48 determines whether or not the low torque urging state is secured again based on the electrical signal from the magnetic sensor 52. Only when this determination is affirmed, the routine proceeds to the next step 108 and the output shaft 38 of the motor 36 is stopped.

  For example, when the occupant is connected to the buckle device by connecting a tongue plate attached to the webbing 16, the rotation of the winding shaft 12 is stopped when the occupant is attached to the webbing 16. Therefore, the ECU 48 moves the motor when the worm wheel 24 that rotates in the pull-out direction following the take-up shaft 12 reaches a position that rotates relative to the take-up shaft 12 from the neutral position by a predetermined angle in the take-up direction. The power supply to 36 is cut off, and the worm wheel 24 is stopped (step 108).

  In this state, the spring spring 26 urges the winding shaft 12 in the winding direction with a constant low torque regardless of the pull-out amount of the webbing 16. As a result, the webbing 16 is in close contact with the occupant's body with a constant low tension, so that the slack of the webbing 16 can be removed and the comfort of the occupant can be ensured.

  When the processing in step 108 is completed, the ECU 48 returns to step 100 described above and repeats the processing as described above. For this reason, in the above-mentioned webbing wearing state, even when the pull-out amount of the webbing 16 changes due to the occupant changing the posture and the winding shaft 12 rotates relative to the worm wheel 24, in steps 100 to 112, Since the ECU 48 controls the operation of the motor 36 so that the low torque biasing state is maintained, the tension acting on the webbing 16 can be made constant. Thereby, a passenger | crew's easiness of movement can be ensured and a passenger | crew's comfort can be improved.

  On the other hand, when the occupant releases the mounted state of the webbing 16, the winding shaft 12 rotates relative to the worm wheel 24 in the winding direction by the urging force of the mainspring spring 26. For this reason, the ECU 48 detects that the winding shaft 12 has rotated relative to the worm wheel 24 in the winding direction based on the electric signal from the magnetic sensor 52 (step 100, step 102). The output shaft 38 is rotated forward to rotate the worm wheel 24 in the winding direction (step 110). The rotational force of the worm wheel 24 is transmitted to the winding shaft 12 via the mainspring 26, and the winding shaft 12 is rotated in the winding direction. As a result, the webbing 16 is wound and stored on the winding shaft 12.

  When the webbing 16 can no longer be wound, the rotation of the winding shaft 12 is stopped. For this reason, the ECU 48 stops the motor 36 when the worm wheel 24 reaches a position relatively rotated by a predetermined angle in the winding direction from the neutral position with respect to the winding shaft 12 (steps 112 and 108). In this state, the winding shaft 12 is biased in the winding direction with low torque by the biasing force of the mainspring spring 26. For this reason, for example, the retracted webbing 16 is prevented from being pulled out unnecessarily due to vibration during vehicle travel.

  As described above, in the webbing retractor 10 according to the first embodiment of the present invention, the pulling-out operation for mounting the webbing, the winding operation of the webbing 16 by the mainspring spring 26, or the movement of the occupant when the webbing is mounted. Is detected by the magnetic sensor 52 (angle sensor), and the ECU 48 operates the motor 36 to maintain the low torque biased state (the state where the worm wheel 24 is disposed at an appropriate relative angle with respect to the winding shaft 12). Therefore, passenger comfort can be improved.

In the first embodiment, the magnet 54 is attached to the take-up shaft 12 and the magnetic sensor 52 is attached to the worm wheel 24. However, the present invention is not limited to this, and the take-up shaft 12 is not limited thereto. The configuration may be such that the magnetic sensor 52 is attached and the magnet 54 is attached to the worm wheel 24.
<Second Embodiment>
Next, a second embodiment of the present invention will be described. In addition, about the structure and effect | action fundamentally similar to the said 1st Embodiment, the same code | symbol as the said 1st Embodiment is provided, and the description is abbreviate | omitted.

  FIG. 3 shows a schematic exploded perspective view of a webbing take-up device 60 according to a second embodiment of the present invention. The webbing take-up device 60 has basically the same configuration as the webbing take-up device 10 according to the first embodiment, but the magnetic sensor 52 according to the first embodiment is omitted. , Another magnetic sensor 62 (first rotation amount detector) attached to the frame 14 is provided. The magnetic sensor 62 is electrically connected to the ECU 48 via wiring, detects the magnitude and direction of the magnetic field (magnetic field) generated by the magnet 54 attached to the winding shaft 12, and sends a predetermined value to the ECU 48. Outputs electrical signals. Thereby, the ECU 48 detects the amount of rotation of the winding shaft 12.

  The motor 36 of the webbing take-up device 60 includes an encoder 64 (second rotation amount detector). The encoder 64 is electrically connected to the ECU 48 via wiring, and detects the number of rotations of the motor 36 and outputs a predetermined electrical signal to the ECU 48.

  The ECU 48 detects the amount of rotation of the worm wheel 24 based on the number of rotations of the motor 36 detected by the encoder 64, and the difference between the amount of rotation of the winding shaft 12 detected by the magnetic sensor 62 and the amount of rotation of the worm wheel 24. Based on the above, the relative rotation amount of the winding shaft 12 with respect to the worm wheel 24 is detected.

  Also in the webbing take-up device 60 having the above-described configuration, the ECU 48 maintains the state in which the worm wheel 24 is relatively rotated by a predetermined angle from the neutral position to the take-up direction with respect to the take-up shaft 12 (low torque urging state). By controlling the operation of the motor 36, there are basically the same effects as the first embodiment.

  In the first embodiment and the second embodiment, the case where the relative rotation amount detection means is configured by the magnetic sensors 52 and 62, the magnet 54, and the encoder 64 has been described. However, the configuration of the relative rotation amount detection means can be changed as appropriate.

  In the first embodiment and the second embodiment, the ECU 48 is in a state where the worm wheel 24 is relatively rotated by a predetermined angle from the neutral position to the winding direction with respect to the winding shaft 12 (low torque biasing). The operation of the motor 36 is controlled so as to always maintain the state), but the present invention is not limited to this. For example, the ECU 48 may perform another control while the webbing 16 is being pulled out or when the webbing 16 is fully retracted.

  In the first and second embodiments, the driving force transmission mechanism (spur gears 34, 40, worm gear 30 and the like) from the motor 36 to the worm wheel 24, and the structure of the worm wheel 24 as a rotating body. The connecting structure between the mainspring 26 and the winding shaft 12 is only one example, and can be changed as necessary.

  In the first embodiment and the second embodiment, the mainspring 26 is applied as a spring. However, the present invention is not limited to this, and a configuration in which a coil spring is applied as a spring may be employed. .

1 is a schematic exploded perspective view showing a configuration of a webbing take-up device according to a first embodiment of the present invention. It is a flowchart of the drive control program memorize | stored in ECU which is a structural member of the webbing winding device concerning a 1st embodiment of the present invention. It is a schematic exploded perspective view which shows the structure of the webbing take-up device according to the second embodiment of the present invention.

Explanation of symbols

10 Webbing Winder 12 Winding Shaft 16 Webbing 24 Worm Wheel (Rotating Body)
26 Spring spring
36 motor 52 magnetic sensor (relative rotation amount detection means)
54 Magnet (relative rotation amount detection means)
46 Driver (control means)
48 ECU (control means)
60 Webbing take-up device 62 Magnetic sensor (relative rotation amount detecting means)
64 Encoder (relative rotation amount detection means)

Claims (4)

Winding the occupant-constrained webbing by being rotated in the winding direction, and the winding shaft being rotated in the pulling-out direction by pulling out the webbing;
A rotating body provided coaxially and relatively rotatably with respect to the winding shaft;
A motor capable of rotating the rotating body in the winding direction and the drawing direction;
A spring that connects the winding shaft and the rotating body, and biases the winding shaft in a direction that cancels the relative rotation when the winding shaft rotates relative to the rotating body;
A relative rotation amount detecting means for detecting a relative rotation amount of the rotating body with respect to the winding shaft;
Control means for adjusting a relative rotation amount of the rotating body with respect to the winding shaft by operating the motor based on a detection result of the relative rotation amount detection means;
A webbing take-up device comprising: Winding the occupant-constrained webbing by being rotated in the winding direction, and the winding shaft being rotated in the pulling-out direction by pulling out the webbing;
A rotating body provided coaxially and relatively rotatably with respect to the winding shaft;
A motor capable of rotating the rotating body in the winding direction and the drawing direction;
A spring that connects the winding shaft and the rotating body, and biases the winding shaft in a direction that cancels the relative rotation when the winding shaft rotates relative to the rotating body;
A relative rotation amount detecting means for detecting a relative rotation amount of the rotating body with respect to the winding shaft;
Control means for maintaining the state in which the rotating body is relatively rotated in the winding direction by a predetermined amount with respect to the winding shaft by operating the motor based on the detection result of the relative rotation amount detecting means;
A webbing take-up device comprising:   The relative rotation amount detection means includes a magnetic sensor attached to one of the winding shaft and the rotating body, and a magnet attached to the other of the winding shaft and the rotating body. The webbing take-up device according to claim 1 or 2.   The relative rotation amount detection means includes a first rotation amount detector that detects a rotation amount of the winding shaft and a second rotation amount detector that detects a rotation amount of the rotating body. The webbing take-up device according to claim 1 or 2.

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