JP5376120B2 - Seat belt retractor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a winding spring device for a seat belt retractor including the function of relaxing fastening onto an occupant's breath during a seat belt attachment in a simpler structure. <P>SOLUTION: The winding spring device for the seat belt retractor 13 includes a retainer 15, a main spring 22, a spring cover 23, a rachet wheel 19, a rotation limiting mechanism 28, a sub spring 18, a spring housing 16, and a plate spring 17. The inner end of the sub spring 18 is fixed to the retainer 15 and the outer end thereof is fixed to the spring housing 16. When a force exceeding a predetermined value in a winding direction "a" is exerted on the spring housing 16 through the sub spring 18 by webbing winding with the rotation of the ratchet wheel 19 in the winding direction "a" limited by the rotation limiting mechanism 28, the spring housing 16 rotates relative to the ratchet wheel 19 together with the plate spring 17. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a seat belt retractor including a webbing take-up spring device.

  A conventional seat belt device includes a main spring that urges the spindle in the winding direction, and a sub spring that generates an urging force in a direction opposite to the main spring. When the seat belt is mounted, the seat Various techniques have been devised for reducing the winding force of the belt to relieve the tightening of the chest of the occupant (see, for example, Patent Document 1).

In the winding spring device described in Patent Document 1, the outer end of the compensation spring, which is a sub-spring, cooperates with a ratchet wheel, which is a ratchet wheel, while the inner end is a spindle via a freewheeling clutch. Cooperate with the shaft. The freewheeling clutch causes force transmission from the shaft to the compensation spring when the pinion wheel is blocked and the shaft rotates in the winding direction, and stress is applied to the compensation spring. Acting in the opposite direction to the torque of the main drive spring. On the other hand, the freewheeling clutch allows relative rotational movement of the compensating spring in the winding direction with respect to the shaft. When the belt is removed from the buckle and the claw wheel is unlocked, the claw wheel rotates in the winding direction on the basis of the stressed compensation spring. The freewheeling clutch allows relative rotation of the compensation spring with respect to the shaft in this direction, so that there is no rapid deceleration of the ratchet wheel when the compensation spring is completely loosened.
JP 2008-111483 A

  By the way, in the winding spring device described in Patent Document 1, the outer end portion of the compensation spring is frictionally engaged with the inner peripheral surface of the ratchet wheel by an extension spring disposed inside the winding. For this reason, by providing a freewheeling clutch, the problem that the expansion spring comes off from the compensation spring when the hook wheel is unlocked can be solved, but the freewheeling clutch itself increases the number of parts and increases the cost. Problems arise.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a seat belt retractor having a simpler structure and a function of alleviating tightening of the chest of an occupant when the seat belt is worn. There is.

The object of the present invention is achieved by the following configurations.
(1) a retainer coupled to a spindle around which the webbing is wound;
A main spring having an inner end connected to the retainer and biasing the spindle in a winding direction;
A case member to which an outer end portion of the main spring is fixed;
A ratchet wheel rotatably arranged around the retainer;
A rotation restricting mechanism for restricting rotation of the ratchet wheel in the winding direction;
A sub-spring having an inner end fixed to the retainer and generating a biasing force in a direction opposite to the main spring;
A spring housing in which an outer end portion of the sub spring is fixed and the sub spring is disposed inside;
One end fixed to the outer peripheral surface of the spring housing and the inner peripheral surface of the ratchet wheel to apply a predetermined surface pressure fitted between the inner peripheral surface of the ratchet wheel and the outer peripheral surface of the spring housing, a free state a plate spring than the inner diameter of the inner peripheral surface of the ratchet wheel that has a larger diameter in,
A webbing take-up spring device having
The rotation restricting mechanism includes a gear that rotates in conjunction with the spindle, and a lever that includes a protrusion that engages with a cam groove formed in the gear, and when the webbing is pulled out from the spindle by a predetermined amount, With the movement of the lever, a lock arm is engaged with the ratchet teeth of the ratchet wheel, and the rotation of the ratchet wheel in the winding direction is restricted,
In the state where the rotation of the ratchet wheel in the winding direction is restricted by the rotation restricting mechanism, a force in the winding direction exceeding a predetermined value is applied to the spring housing via the subspring by the winding of the webbing. Then, the spring housing rotates relative to the ratchet wheel together with the plate spring, and the seat belt retractor includes a webbing take-up spring device.

  In the seat belt retractor of the present invention, the inner end portion of the sub spring is fixed to the retainer, and the outer end portion is fixed to the spring housing. Therefore, even when the ratchet wheel is unlocked, the function of the sub spring can be reliably maintained. In addition, the spring housing and the plate spring can provide the same effect as the freewheeling clutch. Thereby, it is possible to provide a function of reducing the tightening of the occupant's chest when the seat belt is worn with a simpler structure.

  Hereinafter, a seat belt retractor according to an embodiment of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the seat belt retractor 10 includes a retractor frame 11, and a spindle 12 for winding a webbing (not shown) is rotatably supported on the retractor frame 11. A winding spring device 13 for winding the webbing around the spindle 12 is attached to one side in the axial direction.

  The take-up spring device 13 includes a retainer 15, a spring housing 16, a plate spring 17, a sub spring 18, a ratchet wheel 19, a lock, between a gear case 14 attached to one side of the retractor frame 11 in the axial direction and a spring cover 23. An arm 20, a coil spring 21, and a main spring 22 are provided. The winding spring device 13 includes a drive gear 24, a first gear 25, a second gear 26, and a cancel lever 27 on the side of the spring cover 23. The gear case 14 and the spring cover 23 constitute a case member of the present invention.

  The spring cover 23 is formed with a recess (not shown) for accommodating the main spring 22. The main spring 22 is disposed between the spring cover 23 and the ratchet wheel 19. A sub spring 18, a plate spring 17, and a spring housing 16 are disposed between the ratchet wheel 19 and the gear case 14 so as to be accommodated inside the ratchet wheel 19.

  The retainer 15 is fitted and fixed to one end of the spindle 12 in the axial direction, and rotates integrally with the spindle 12. The retainer 15 includes a large-diameter shaft portion 15c in which two slits 15a and 15b are formed, and a small-diameter shaft portion 15d that protrudes in the axial direction at the tip thereof. The large-diameter shaft portion 15 c passes through center holes 16 a and 19 a formed in the spring housing 16 and the ratchet wheel 19. The small diameter shaft portion 15 d passes through a center hole 23 a formed in the spring cover 23.

  The main spring 22 is accommodated in the spring cover 23 and is wound in a spiral shape so as to be biased in the winding direction a from the inside toward the outside. The inner end of the main spring 22 is engaged with the slit 15 a of the retainer 15 and connected to the retainer 15, and the outer end is locked and fixed to a locking portion (not shown) formed in the spring cover 23. Has been. When the webbing is pulled out from the spindle 12 and the retainer 15 rotates in the pulling direction b, the main spring 22 is wound and the spindle 12 is urged together with the retainer 15 in the winding direction a by the urging force.

  The subspring 18 has a smaller number of turns than the main spring 22 and is wound in a spiral shape so as to be biased from the inside toward the outside in the pulling direction b. The inner end portion of the sub spring 18 is engaged with the slit 15 b of the retainer 15 and connected to the retainer 15, and the outer end portion is locked and fixed to a locking portion 16 b formed on the spring housing 16. The sub spring 18 can generate an urging force in the pulling direction b (the direction opposite to the main spring) with respect to the retainer 15.

  The spring housing 16 includes a disk portion 16c in which a center hole 16a is formed, and an annular portion that extends in the axial direction from a side surface near the outer peripheral surface of the disk portion 16c and in which a locking portion 16b is formed in a part of the circumferential direction. 16d. A locking groove 16e for locking and fixing the plate spring 17 is formed in another part of the annular portion 16d in the circumferential direction. A subspring 18 having an outer end fixed to the locking portion 16b is disposed inside the annular portion 16d. A plate spring 17 having one end fixed to the locking groove 16e is disposed outside the annular portion 16d.

  The plate spring 17 is formed to have a larger diameter than the inner diameter of the inner peripheral surface of the annular portion 19b of the ratchet wheel 19 in a free state. In a state where one end of the plate spring 17 is fixed to the spring housing 16, as shown by an arrow c in FIG. 5, a predetermined surface pressure is applied to the inner peripheral surface of the ratchet wheel 19 and fitted.

  The ratchet wheel 19 is rotatably disposed around the retainer 15. The ratchet wheel 19 is formed by a disk portion 19b having a center hole 19a and an annular portion 19d extending in the axial direction from the side surface of the disk portion 19b and having ratchet teeth 19c on the outer peripheral surface. The annular portion 19 d of the ratchet wheel 19 has an inner diameter larger than the outer diameter of the annular portion 16 d of the spring housing 16. The annular portion 16 d of the spring housing 16 is disposed in the annular portion 19 d of the ratchet wheel 19.

  The lock arm 20, the coil spring 21, the drive gear 24, the first gear 25, the second gear 26, and the cancel lever 27 constitute a rotation restricting mechanism that restricts the rotation of the ratchet wheel 19 in the winding direction a.

  The drive gear 24 is coupled to a small-diameter shaft portion 15 d of the retainer 15 that extends from the center hole 23 a of the spring cover 23. The first and second gears 25 and 26 are rotatably attached to the side surface of the spring cover 23. The drive gear 24 meshes with the large gear 25 a of the first gear 25. The small gear 25 b of the first gear 25 meshes with the second gear 26. The cancel lever 27 is formed in a substantially V shape and is supported on the side surface of the spring cover 23 so as to be swingable. One arm portion 27 a of the cancel lever 27 has a protrusion 27 b that engages with a cam groove 26 a that is spirally formed on one side surface of the second gear 26.

  The lock arm 20 includes three arms 20a, 20b, and 20c, and is rotatably supported by the gear case 14. The first arm 20 a is provided with a convex portion 20 d that protrudes in the axial direction from an arc hole 23 b formed in the spring cover 23, and comes into contact with the other arm portion 27 c of the cancel lever 27.

  A coil spring 21 is spanned between the second arm 20 b of the lock arm 20 and the gear case 14. The third arm 20 c is disposed so as to be able to engage with and disengage from the ratchet teeth 19 c of the ratchet wheel 19.

  In the state where the webbing is not pulled out (the webbing retracted state), the rotation restricting mechanism has the protrusion 27b of the cancel lever 27 positioned at the outer end of the cam groove 26a of the second gear 26 as shown in FIG. The cancel lever 27 presses the convex portion 20d of the lock arm 20 so that the third arm 20c of the lock arm 20 moves away from the ratchet teeth 19c of the ratchet wheel 19 against the urging force of the coil spring 21.

  On the other hand, when the webbing is pulled out by a predetermined amount, as shown in FIG. 3, the cancel lever 27 has its protrusion 27 b at the intermediate portion of the cam groove 26 a of the second gear 26 according to the rotation of the second gear 26. To position. This position is a position where the cancel lever 27 releases the convex portion 20 d of the lock arm 20. The third arm 20 c of the lock arm 20 is engaged with the ratchet teeth 19 c of the ratchet wheel 19 by the biasing force of the coil spring 21. Thereby, the ratchet wheel 19 is prevented from rotating in the winding direction a. When the webbing is pulled out, the ratchet wheel 19 is rotated in the pulling direction b while the third arm 20c of the lock arm 20 gets over the ratchet teeth 19c.

  FIG. 4 shows a state in which the retainer 15 is rotated by the rotational biasing force of the main spring 22 and the webbing is wound up in a state where the rotation of the ratchet wheel 19 in the winding direction a is restricted by the rotation restricting mechanism. The plate spring 17 and the ratchet wheel 19 are frictionally engaged by a predetermined surface pressure. The subspring 18 rotates in the winding direction a by the rotation of the retainer 15. As a result, as shown in FIG. 5, the sub-spring 18 is tightened and accumulates a rotational urging force (torque) in the pull-out direction b with respect to the retainer 15. Here, the number of rotations of the sub-spring 18 is arbitrarily set by setting the surface pressure that determines the frictional force of the plate spring 17 against the ratchet wheel 19. The reaction force of the sub spring 18 acts on the spring housing 16 by winding. When the frictional force determined by the surface pressure between the plate spring 17 and the ratchet wheel 19 exceeds a predetermined frictional force (predetermined value), the spring housing 16 is moved together with the plate spring 17 against the ratchet wheel 19 as shown in FIG. Relative rotation. The spring housing 16 rotates while receiving a predetermined frictional force.

  Next, the operation of the winding spring device will be described together with the operation when the occupant wears / releases the seat belt.

1) When the webbing is started when the webbing is mounted on the occupant, the retainer 15 rotates in the pulling direction b together with the spindle 12 (see FIG. 1). The ratchet wheel 19 rotates in the pull-out direction b via the sub spring 18, the spring housing 16, and the plate spring 17. The ratchet wheel 19 can rotate freely. Since the sub-spring 18 is not tightened, no rotational biasing force in the pulling direction b is generated with respect to the retainer 15. In this case, only the rotational biasing force of the main spring 22 acts as the webbing pull-out force.

2) When the webbing is pulled out beyond a predetermined amount, as shown in FIG. 3, the ratchet wheel 19 is prevented from rotating in the winding direction (winding direction a: see FIG. 1). The ratchet wheel 19 rotates in the pull-out direction b while the third arm 20c of the lock arm 20 gets over the ratchet teeth 19c.

3) After the webbing is mounted on the occupant, the excess slack portion of the webbing is wound up by the spring force of the main spring 22. The rotation of the ratchet wheel 19 in the winding direction a is restricted by the rotation restricting mechanism. The retainer 15 is rotated in the winding direction a by the main spring 22. The plate spring 17 and the ratchet wheel 19 are engaged by friction. As shown in FIG. 5, the subspring 18 rotates in the winding direction a until the reaction force of the subspring 18 due to winding exceeds a predetermined frictional force between the plate spring 17 and the ratchet wheel 19. During this time, the sub-spring 18 is wound up, and the sub-spring 18 accumulates the rotational urging force in the pulling direction b with respect to the retainer 15. Thereby, the winding force of the retainer 15 is reduced. Therefore, when the webbing is fitted to the occupant, tightening of the occupant on the chest is eased. When the reaction force of the sub-spring 18 due to winding exceeds a predetermined frictional force between the plate spring 17 and the ratchet wheel 19, the spring housing 16 rotates relative to the ratchet wheel 19 together with the plate spring 17.

4) When the seat belt is released and the webbing is taken up, it is wound in a state where the take-up force of the retainer 15 is reduced by the sub-spring 18 until the webbing is taken up by a predetermined amount. When the ratchet hole 19 is disengaged from the lock arm 20 after being wound up by a predetermined amount, it is wound by the rotational biasing force of the main spring 22. When the engagement by the lock arm 20 is released, the ratchet wheel 19 starts to rotate again in the winding direction a. The plate spring 17 and the spring housing 16 that have been engaged with the ratchet wheel 19 by the frictional force are rotated in the direction of loosening the spring force of the sub spring 18 relative to the ratchet wheel 19 by the torque of the sub spring 18. The spring force of the spring 18 is released. At this time, since both end portions of the sub spring 18 are fixed by the spring housing 16 and the retainer 15, they do not come off even if the torque is released at a high speed.

  As described above, according to the retractor spring device 13 for the seat belt retractor of the present embodiment, the inner end portion of the sub spring 18 is fixed to the retainer 15 and the outer end portion is fixed to the spring housing 16. Even when the ratchet wheel 19 is unlocked, the function of the sub-spring 18 can be reliably maintained, and the spring housing 16 and the plate spring 17 can provide the same effect as a conventional freewheeling clutch. With a simple structure, it has a function to relieve the tightening of the passenger's chest when the seat belt is worn.

  In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.

  For example, in the present embodiment, the rotation restricting mechanism is configured to drive the rocker arm by the drive gear, the first and second gears, and the cancel lever, but the rocker arm is driven by a solenoid actuator or the like. It may be configured.

It is a disassembled perspective view for demonstrating the component of the seatbelt retractor which is one Embodiment of this invention. It is a side view of the winding spring device at the time of starting the webbing pull-out operation. It is a side view of a winding spring device at the time of pulling out a predetermined amount of webbing. It is a figure which shows the inside of the ratchet wheel of the winding spring apparatus at the time of winding start of webbing. It is a figure which shows the inside of the ratchet wheel of the winding spring apparatus at the time of winding a predetermined amount of webbing. It is a figure which shows the inside of the ratchet wheel of the winding spring apparatus at the time of winding over the predetermined amount of webbing.

Explanation of symbols

10 Seat belt retractor (seat belt device)
12 Spindle 13 Winding spring device 14 Gear case 15 Retainer 16 Spring housing 17 Plate spring 18 Sub spring 19 Ratchet wheel 20 Lock arm (rotation restricting mechanism)
21 Coil spring (rotation restriction mechanism)
22 Main spring 23 Spring cover 24 Drive gear (rotation restricting mechanism)
25 1st gear (rotation restricting mechanism)
26 Second gear (rotation restricting mechanism)
27 Cancel lever (rotation restricting mechanism)

Claims (1)

A retainer coupled to a spindle around which the webbing is wound;
A main spring having an inner end connected to the retainer and biasing the spindle in a winding direction;
A case member to which an outer end portion of the main spring is fixed;
A ratchet wheel rotatably arranged around the retainer;
A rotation restricting mechanism for restricting rotation of the ratchet wheel in the winding direction;
A sub-spring having an inner end fixed to the retainer and generating a biasing force in a direction opposite to the main spring;
A spring housing in which an outer end portion of the sub spring is fixed and the sub spring is disposed inside;
One end fixed to the outer peripheral surface of the spring housing and the inner peripheral surface of the ratchet wheel to apply a predetermined surface pressure fitted between the inner peripheral surface of the ratchet wheel and the outer peripheral surface of the spring housing, a free state a plate spring than the inner diameter of the inner peripheral surface of the ratchet wheel that has a larger diameter in,
A webbing take-up spring device having
The rotation restricting mechanism includes a gear that rotates in conjunction with the spindle, and a lever that includes a protrusion that engages with a cam groove formed in the gear, and when the webbing is pulled out from the spindle by a predetermined amount, With the movement of the lever, a lock arm is engaged with the ratchet teeth of the ratchet wheel, and the rotation of the ratchet wheel in the winding direction is restricted,
In the state where the rotation of the ratchet wheel in the winding direction is restricted by the rotation restricting mechanism, a force in the winding direction exceeding a predetermined value is applied to the spring housing via the subspring by the winding of the webbing. Then, the spring housing rotates relative to the ratchet wheel together with the plate spring, and the seat belt retractor includes a webbing take-up spring device.

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