JP2009078633A - Seat belt retractor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seat belt retractor capable of performing sufficient clutch action by a small number of parts. <P>SOLUTION: The clutch 52 is provided with a latch ring 50 rotated with a spindle 12 and having an external tooth 50a on an outer peripheral surface; a swingable pawl 49 moved according to rotation of a motor 34 and having an engagement part 49a engageable with the external tooth 50a of the latch ring 50; and a friction spring 42 having one end 42a abuttable on an outer surface 49a of the pawl 49 and the other end 42b abuttable on an inner surface 49b of the pawl 49 and capable of retaining the pawl 49. When the pawl 49 is started to be moved in a direction for rolling-up a seat belt, the friction spring 42 receives friction force in a reverse direction to the rolling-up direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a seat belt retractor, and more particularly to a seat belt retractor including an electric actuator using a motor.

  In a conventional seat belt retractor, a sudden deceleration state of a vehicle is detected by a sensor, and a spindle is rotated in a winding direction by a motor. When there is a possibility of a collision, the seat belt (webbing) is wound around a certain amount to restrain the occupant lightly, and at the time of the collision, the restraining force is increased to hold the occupant securely (for example, patent Reference 1 and 2).

  In the seatbelt retractors described in Patent Documents 1 and 2, in the power transmission mechanism that transmits the power from the electric actuator to the spindle, a clutch is interposed to prevent the rotation from the spindle side from being transmitted to the electric actuator. Yes.

  The clutch described in Patent Document 1 includes a gear wheel and a rotor that rotate by transmission of rotation of an electric actuator. The rotor is supported by a pawl that is constantly urged in the direction of engagement with the spindle by an urging member, and this pawl is normally held in a disengaged position from the spindle by a holding member provided on the rotor. Has been. When the rotor is rotated about one axis by the driving force of the motor, the holding of the pawl by the holding member is released, and the pawl is engaged with the spindle by the urging force of the urging member. Thereby, the rotation of the rotor is transmitted to the spindle and the spindle rotates. On the other hand, when the rotor rotates around the axis to the other, the holding member moves and holds the pawl to the disengagement position with the spindle against the urging force of the urging member.

In addition, the holding member and the pawl form an inclined surface that generates a drag force in the separation direction so as to maintain the mutual holding state in a state where the rotor is stopped, thereby preventing erroneous clutch engagement.
JP 2006-103657 A JP 2004-42782 A

  By the way, in the seat belt retractor, the pawl is urged and rotated in the direction of coupling with the motor by a torsion spring or a leaf spring. For this reason, when an impact is applied from the outside, the urging force to the pawl is weakened by this impact, and there is a possibility that the operation is delayed and a malfunction occurs. In addition, the clutch has a large number of parts, and there is a problem that assembly work is complicated.

  The present invention has been made in view of the above-described circumstances, and it is an object of the present invention to provide a seatbelt retractor capable of performing a good clutch operation with a small number of parts.

The above object of the present invention is achieved by the following configurations.
(1) a spindle for winding up a seat belt;
An electric actuator that generates power to rotate the spindle;
A power transmission mechanism capable of transmitting power from the electric actuator to the spindle;
A seat belt retractor comprising:
The power transmission mechanism is
A rotating member that rotates with the spindle and has an engaged portion on the peripheral surface;
A swingable engaging member that moves according to the rotation of the electric actuator and has an engaging portion that can be engaged with an engaged portion of the rotating member;
An engagement member holding body capable of holding the engagement member by contacting the engagement member;
With
The retractor for a seat belt according to claim 1, wherein the engaging member holding body receives a force in a direction opposite to the winding direction when the engaging member starts to move in the winding direction of the seat belt.

(2) The engagement member holding body operates so as to release the force received in the reverse direction by the swinging of the engagement member in a state where the force in the reverse direction to the winding direction is received. The retractor for seat belts as described in (1).

(3) The retractor for a seat belt according to (1) or (2), wherein the force received in the reverse direction is a frictional force.

(4) The engagement member holding body is a substantially ring-shaped friction spring,
The friction spring is held with its inner peripheral surface or outer peripheral surface in contact with the convex portion of the case member by its urging force, according to any one of (1) to (3). Seat belt retractor.

(5) The engagement member holding body has one end capable of abutting on the outer surface of the engagement member and the other end capable of abutting on the inner surface of the engagement member. A retractor for a seat belt according to any one of Items (1) to (4).

(6) a spindle for winding up the seat belt;
An electric actuator that generates power to rotate the spindle;
A power transmission mechanism capable of transmitting power from the electric actuator to the spindle;
A seat belt retractor comprising:
The power transmission mechanism is
A rotating member that rotates with the spindle and has an engaged portion on the peripheral surface;
A swingable engaging member that moves according to the rotation of the electric actuator and has an engaging portion that can be engaged with an engaged portion of the rotating member;
An engaging member holding having one end capable of contacting the outer surface of the engaging member and the other end capable of contacting the inner surface of the engaging member and supported by the case member by its own urging force Body,
With
When the engagement member moves in response to the rotation of the electric actuator, the engagement member holding body abuts on the outer surface and the inner surface of the engagement member, rotates relative to the case member, and A retractor for a seat belt, which moves in synchronization with an engaging member.

(7) It further includes a plate member that holds the engaging member in a swingable manner.
(6) characterized in that both ends of the engaging member holder are respectively accommodated in a pair of elongated holes formed in the plate member along the circumferential direction and longer than the circumferential width of the both ends. The retractor for seatbelts described.

  According to the seat belt retractor of the present invention, the engaging member holding body is configured to receive a force in a direction opposite to the winding direction when the engaging member starts to move in the direction of winding the seat belt. . Accordingly, the engaging member holding body moves integrally with the engaging member interposed therebetween, and this movement causes the movement of the engaging member to generate a force in the direction opposite to the winding direction on the engaging member holding body. Make your body easier to rotate. This makes it possible to perform a good clutch operation with a small number of parts.

  Next, a seatbelt 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 of the present embodiment includes a spindle 12 that winds up a seat belt (not shown), and a winding spring device 13 that biases the spindle 12 in the seat belt winding direction. A lock mechanism 14 that locks the seat belt pull-out operation in accordance with acceleration detected by an acceleration sensor (not shown), a motor 34 that is an electric actuator that generates power for rotating the spindle 12, and a motor 34 And a power transmission mechanism 17 capable of transmitting the power to the spindle 12.

  Both ends of the spindle 12 are rotatably supported by the support frame 11. Further, a torsion bar (not shown) constituting an energy absorption mechanism is provided in the spindle 12.

  Further, a lower cover 25 and an upper cover 53 that are case members are attached to the left side surface of the support frame 11 in the drawing with a screw 27 via a bearing ring 24. A space for accommodating the power transmission mechanism 17 is formed between the lower cover 25 and the upper cover 53 attached thereto.

  A motor assembly 16 is attached to a lower portion of the lower cover 25, that is, a position below the support frame 11. The motor assembly 16 includes a rear cap 31, a printed circuit board 32, a rear case 33, a motor 34, an O-ring 37, a first gear 35, and a front case 36. The first gear 35 is attached to the rotating shaft of the motor 34, is inserted into the lower cover 25, and meshes with the second gear 54 of the torque limiter mechanism 19 provided in the power transmission mechanism 17.

  The torque limiter mechanism 19 includes a third small gear 59 that meshes with the fourth gear 58, a spring holder 55 that is rotatably attached to the third small gear 59, and a plurality of limit springs 56 that are held by the spring holder 55. And a third large gear 57 which is arranged coaxially with the third small gear 59 and meshes with the second gear 54. While the limit spring 56 is held by the spring holder 55, one end is engaged with an uneven surface (not shown) formed on the inner peripheral surface of the third large gear 57 and elastically deformed to form a third. The relative rotation of the large gear 57 with respect to the third small gear 59 is allowed.

  For this reason, in the torque limiter mechanism 19, the third large gear 57 and the third small gear 59 are rotated in the same direction while maintaining a relative phase by the limit spring 56 in the normal state. Here, at the time of winding by driving the motor 34, a torque difference larger than a predetermined value is caused between the third large gear 57 and the third small gear 59 due to a light collision or braking that the pretensioner mechanism 15 does not operate. When this occurs, the engagement between the one end of the limit spring 56 and the uneven surface of the third large gear 57 is released, and slipping starts while elastically deforming. As a result, transmission of excessive torque by the motor 34 can be suppressed, the gear teeth can be prevented from being damaged, and the influence on the restraint performance during the energy absorbing operation can be reduced. In the present embodiment, the first gear 35, the second gear 54, the third small gear 59, the third large gear 57, the fourth gear 58, and a final gear 47, which will be described later, constitute a gear assembly.

  Further, a clutch 52 constituting the power transmission mechanism 17 is accommodated in the upper part between the lower cover 25 and the upper cover 53. The clutch 52 includes a friction spring 42 as an engaging member holding body, a ring plate 46 as a plate member, a final gear 47, a pawl 49 as an engaging member, a latch ring 50 as a rotating member, and a bush 51. The

  The latch ring 50 is coupled with a joint 22 and an internal tooth (not shown) integrally attached to the spindle 12 and rotates integrally with the spindle 12, and an external tooth which is an engaged portion on the outer peripheral surface. 50a (see FIG. 3).

  The final gear 47 is arranged coaxially with the latch ring 50 and is gear-coupled to the rotating shaft of the motor 34. The ring plate 46 is attached to the final gear 47 and rotates integrally with the final gear 47.

  The pawl 49 is swingably supported by the ring plate 46 by a pin 43 attached to the ring plate 46 and an E-shaped clip 44, and an engaging portion 49c that engages with the external teeth 50a of the latch ring 50 at the tip. (See FIG. 3).

  The friction spring 42 is held in contact with the outer peripheral surface of the convex portion 25 a formed on the lower cover 25 by urging the convex portion 25 a toward the center of the rotation axis of the spindle 12 by its urging force. As a result, when the friction spring 42 receives a force in the rotational direction, it generates a frictional force in the direction opposite to the rotational direction between the friction spring 42 and the convex portion 25 a of the lower cover 25. The convex portion 25a protrudes in the axial direction from the side surface of the case, and is formed concentrically with the central hole 25b through which the joint 22 passes.

  The friction spring 42 is formed in a substantially ring shape in cross section with both ends 42a and 42b partially opened. Moreover, these both ends 42a and 42b are each accommodated in a pair of long holes 46a and 46b longer than the circumferential width of both ends 42a and 42b formed in the ring plate 46 along the circumferential direction. Accordingly, the friction spring 42 held by the convex portion 25 a of the lower cover 25 is restricted from moving in the circumferential direction with respect to the ring plate 46.

  Further, in the friction spring 42, one end 42 a can be brought into contact with the outer surface 49 a of the pawl 49 while the both ends 42 a and 42 b are accommodated in the pair of long holes 46 a and 46 b, and the other end 42 b is in the pawl 49. It can come into contact with the side surface 49b. Thereby, the friction spring 42 guides the outer surface 49a or the inner surface 49b of the pawl 49 by the one end 42a or the other end 42b when the pawl 49 moves together with the ring plate 46 in the rotation direction. In addition, with the other end 42b of the friction spring 42 being fixed by the inner side surface of the pawl 49 by the swing of the pawl 49, the one end 42a is expanded by contacting the outer side surface 49a of the pawl 49, and the biasing force against the convex portion 25a Make it smaller.

  Next, the operation of the seatbelt retractor 10 of this embodiment will be described. When the possibility of a collision is detected by a monitoring sensor (not shown) or the like, the motor 34 is driven before the collision by an ECU (not shown), and the spindle 12 is rotated via the power transmission mechanism 17 to wind the seat belt. When the possibility of the collision is lost, the motor 34 is reversed to return to the state before the collision.

Here, the operation of the clutch 52 will be described with reference to FIGS.
First, as shown in FIG. 3, when the winding by the motor 34 is not performed, the pawl 49 is regulated by contacting the other end 42b of the friction spring 42 with the inner side surface 49b, and the engaging portion 49c. Is away from the latch ring 50, and the latch ring 50 and the pawl 49 are not engaged. For this reason, only the latch ring 50 integral with the spindle 11 can be rotated, and the seat belt can be normally wound and pulled out.

  As shown in FIG. 4, when the motor 34 rotates to the winding side, the final gear 47 that is gear-coupled to the rotating shaft of the motor 34 rotates counterclockwise (arrow A direction). In the state of starting rotation, when the pawl 49 moves counterclockwise together with the final gear 47, the outer surface 49a is guided in contact with one end 42a of the friction spring 42, and the engaging portion 49c moves toward the center of the rotation axis of the spindle 12. Moving. In this state, since the frictional force between the friction spring 42 and the projection 25a is smaller than the pressing force of the pawl 49, the friction spring 42 is held without moving relative to the projection 25a.

  As shown in FIG. 5, when the pawl 49 further swings counterclockwise while being guided by the one end 42 a of the friction spring 42, the engaging portion 49 c engages with the external teeth 50 a of the latch ring 50. Then, the latch ring 50 rotates together with the final gear 47 counterclockwise. As a result, the rotation of the final gear 47 is transmitted to the spindle 12 via the latch ring 50, and the seat belt starts to be wound.

  At this time, one circumferential side of the other end 42 b of the friction spring 42 contacts the circumferential edge of the elongated hole 46 b of the ring plate 46, while the other circumferential side of the other end 42 b is pawl 49. Further, the circumferential one side portion of the one end 42a of the friction spring 42 contacts the outer surface 49a of the pawl 49 without contacting the circumferential edge of the long hole 46a. . For this reason, a force for spreading the friction spring 42 acts, and the frictional force between the friction spring 42 and the convex portion 25a is reduced, and the friction spring 42 moves away from the convex portion 25a and rotates together with the ring plate 46. .

  When the motor 34 rotates on the release side, that is, in the direction B in FIG. 5, the final gear 47 rotates clockwise. The pawl 49 also moves clockwise by the rotation of the ring plate 46, the outer surface 49a is separated from one end 42a of the friction spring 42, and the inner surface 49b is guided to the other end 42b of the friction spring 42, while the pawl 49b is Rotating clockwise, the engaging portion 49 c is separated from the external teeth 50 a of the latch ring 50, and the pawl 49 is disengaged from the latch ring 50.

  According to the seatbelt retractor 10 described above, the clutch 52 rotates together with the spindle 12, moves according to the rotation of the latch ring 50 having the outer teeth 50a on the outer peripheral surface, and the motor 34, and the latch ring. 50, a swingable pawl 49 having an engaging portion 49a engageable with the external teeth 50a, an end 42a capable of contacting the outer surface 49a of the pawl 49, and an inner surface 49b of the pawl 49. A friction spring 42 having a second end 42b and capable of holding the pawl 49. The friction spring 42 receives a frictional force in the direction opposite to the winding direction when the pawl 49 starts to move in the direction in which the seat belt is wound. Accordingly, the friction spring 42 moves integrally with the pawl 49 sandwiched therebetween, and the movement of the pawl 49 generates a frictional force in the direction opposite to the winding direction on the friction spring, thereby facilitating the rotation of the friction spring 42. This makes it possible to perform a good clutch operation with a small number of parts.

  Further, the friction spring 42 operates so as to release the force received in the reverse direction by the swing of the pawl 49 in a state where the force is applied in the direction opposite to the winding direction. While guiding, it can smoothly rotate together with the spindle 12 during winding, and a better clutch operation can be given.

  Further, the ring-shaped friction spring 42 urged toward the center of the rotation axis of the spindle 12 is held by the convex portion 25a of the lower cover 25, so that the friction force is applied with a simpler structure. Is done.

  The seat belt retractor described above is a preferred example of the present invention, and other embodiments can be implemented or performed by various methods. The invention is not limited to the detailed shape, size, configuration, and the like of the components shown in the accompanying drawings unless otherwise specified in the present specification. In addition, expressions and terms used in the present specification are for the purpose of explanation, and are not limited thereto unless otherwise specified.

  For example, in the above-described embodiment, the friction spring 42 is held on the outer peripheral surface of the convex portion 25a of the lower cover 25 by the biasing force in the direction of the rotation axis, but the friction spring 42 has a radius on the inner peripheral surface of the convex portion 25a. It may be held by an urging force spreading in the direction. In this case, the friction spring 42 can be synchronously rotated with the ring plate 46 by reducing the diameter of the friction spring 42 by the pawl 49.

  Specifically, as shown in FIG. 6, the pawl 49 includes a pressing portion 49 d having an inner surface 49 a and an outer surface 49 b that are in contact with both ends 42 a and 42 b of the friction spring 42 in addition to the engaging portion 49 c. Then, when the motor 34 rotates to the winding side, the friction spring 42 may be reduced in diameter by swinging so that the pawl 49 engages with the latch ring 50.

It is a disassembled perspective view of the retractor for seatbelts concerning this invention. It is sectional drawing which shows the structure in the gear case of FIG. It is a figure for demonstrating the normal action | operation of the clutch which transmits the motive power from a motor. It is a figure for demonstrating the action | operation at the time of winding of the clutch which transmits the motive power from a motor. It is a figure for demonstrating the action | operation at the time of cancellation | release of the clutch which transmits the motive power from a motor. It is a figure which concerns on the modification in the case of reducing the diameter of a friction spring at the time of winding of a clutch.

Explanation of symbols

10 Retractor for seat belt 12 Spindle 17 Power transmission mechanism 34 Motor (electric actuator)
42 Friction spring (engaging member holder)
46 Ring plate (plate member)
49 Paul (engagement member)
49c engaging part 50 latch ring (rotating member)
50a External tooth (engaged part)
52 Clutch

Claims (7)

A spindle that winds up the seat belt;
An electric actuator that generates power to rotate the spindle;
A power transmission mechanism capable of transmitting power from the electric actuator to the spindle;
A seat belt retractor comprising:
The power transmission mechanism is
A rotating member that rotates with the spindle and has an engaged portion on the peripheral surface;
A swingable engaging member that moves according to the rotation of the electric actuator and has an engaging portion that can be engaged with an engaged portion of the rotating member;
An engagement member holding body capable of holding the engagement member by contacting the engagement member;
With
The retractor for a seat belt according to claim 1, wherein the engaging member holding body receives a force in a direction opposite to the winding direction when the engaging member starts to move in the winding direction of the seat belt.   The engagement member holding body operates so as to release the force received in the reverse direction by the swinging of the engagement member in a state of receiving a force in a direction opposite to the winding direction. Item 2. The seatbelt retractor according to Item 1.   The retractor for a seat belt according to claim 1, wherein the force received in the reverse direction is a frictional force. The engagement member holding body is a substantially ring-shaped friction spring,
The seat belt according to any one of claims 1 to 3, wherein the friction spring is held with its inner peripheral surface or outer peripheral surface in contact with a convex portion of the case member by its urging force. For retractor.   The said engaging member holding body has one end which can be contact | abutted with the outer surface of the said engagement member, and the other end which can be contact | abutted with the inner surface of the said engagement member. The retractor for seatbelts in any one of 4. A spindle that winds up the seat belt;
An electric actuator that generates power to rotate the spindle;
A power transmission mechanism capable of transmitting power from the electric actuator to the spindle;
A seat belt retractor comprising:
The power transmission mechanism is
A rotating member that rotates with the spindle and has an engaged portion on the peripheral surface;
A swingable engaging member that moves according to the rotation of the electric actuator and has an engaging portion that can be engaged with an engaged portion of the rotating member;
An engagement member holding body having one end capable of contacting the engagement member and the other end capable of contacting the inner surface of the engagement member and supported by the case member by its urging force;
With
When the engagement member moves in response to the rotation of the electric actuator, the engagement member holding body abuts on the outer surface and the inner surface of the engagement member, rotates relative to the case member, and A retractor for a seat belt, which moves in synchronization with an engaging member. A plate member for swingably holding the engagement member;
The both ends of the engaging member holding body are respectively accommodated in a pair of long holes longer than the circumferential width of the both ends formed in the plate member along the circumferential direction. The retractor for seatbelts described.

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