JPH0740449Y2 - Seat belt retractor - Google Patents

Description

[Detailed Description of the Invention] [Industrial application] The present invention relates to a seat belt retractor, and more particularly to a spring means for urging the webbing in the winding direction in order to reduce the feeling of pressure when the seat belt is worn. Relates to a seat belt retractor which is tensioned to remove the slack of the webbing and winds the webbing by a motor when the webbing is stored.

[Prior art and its problems]

As an example of a conventional seat belt retractor of this type, there is one disclosed in Japanese Utility Model Laid-Open No. 58-80254.
The seat belt retractor of this publication is provided with spring means having a minimum tension to remove the slack of the webbing, and when the seat belt is attached, the spring means lightly urges the webbing in the winding direction. When the belt is disengaged, the buckle dissociation signal is detected and the motor winds the webbing for a predetermined time.

However, in such a conventional seat belt retractor, the drive of the motor is limited only to the set time, so that the set time elapses when the webbing or the tongue catches on the passenger or the interior parts of the vehicle. Sometimes, the motor stopped and the winding of the webbing was not completed.

Another example of a conventional seat belt retractor is disclosed in Japanese Utility Model Laid-Open No. 56-27156. The seat belt retractor disclosed in this publication is a spring means having a minimum tension and a buckle release button. And a webbing take-up motor that is driven only while pressing.

However, in such a conventional seat belt retractor, in order to wind up the webbing, the buckle release button has to be continuously pressed, which is troublesome to operate.

The applicant of the present invention has already applied for a seat belt retractor that overcomes the problems of the conventional ones.

This prior application is connected to a spindle for supporting a take-up drum of a webbing, and a spring means for constantly applying a spring force to the spindle to remove a slack of the webbing, and a tongue for mounting the webbing on an occupant. A detection means for detecting dissociation from the buckle, a motor driven by the buckle dissociation signal from the detection means to rotate the spindle in the webbing winding direction, and a tension detection means for detecting tension acting on the webbing,
There is provided switch means for stopping the energization of the motor when the tension of the webbing detected by the tension detecting means exceeds a predetermined value, and holding means for holding the stopped state of the energization of the motor by the switch means. It was done.

However, since the one in this prior application specifically uses a one-way clutch, noise may be generated from the ratchet, and the tension acting on the webbing when the webbing is pulled out when the seat belt is worn varies. Since the switch means reacts sensitively to the tension detecting means,
The so-called hiccup phenomenon may occur when the motor repeatedly turns on and off.

[Purpose of device]

The present invention overcomes the above-mentioned problems in the prior art, and allows the webbing to be wound up easily and reliably by a motor, and does not generate noise from the ratchet, and does not cause a hiccup phenomenon when the seat belt is worn. The purpose of the present invention is to provide a seat belt retractor.

[Outline of device]

The present invention relates to a spring means that is connected to a spindle that supports a take-up drum of a webbing, and that constantly applies a spring force to the spindle to remove slack of the webbing, and a tongue buckle for mounting the webbing to an occupant. Detecting means for detecting the disengagement of the webbing, a motor driven by the buckle dissociation signal from the detecting means to rotate the spindle in the webbing winding direction via an inertial clutch, and a tension detection for detecting the tension acting on the webbing. Means, switch means for stopping energization to the motor when the tension of the webbing detected by the tension detecting means exceeds a predetermined value, and winding of the webbing by a predetermined amount or more by the spring means. Only by switching the switch means by winding the webbing. When the webbing is not wound more than a predetermined amount, it has a holding means for holding the state where the energization of the motor by the switch means is stopped. Even if the webbing tension rises and the motor stops,
When a decrease in tension due to the release of this catch is detected, the motor is re-energized to perform winding, and the webbing is completely wound around the winding drum and the tension of the webbing exceeds a predetermined value. To stop energizing the
Also, the pawl is engaged with the ratchet only when the webbing is wound by the motor by the inertial clutch so that noise is not generated, and the holding means sensitively changes the tension acting on the webbing when the webbing is pulled out to the switch means. It is designed to prevent the hiccup phenomenon by not transmitting it.

[Example of device]

 Hereinafter, the present invention will be described with reference to the embodiments shown in the drawings.

1 and 2 show an entire seat belt retractor according to the present invention. A retractor body 1 attached to a vehicle body is a substrate 2 fixed to the vehicle body.
And a pair of side plates 3A and 3B that are integrally erected in parallel so as to face both side edges of the substrate 2 and are formed in a substantially U-shaped cross section. In the center of both side plates 3A, 3B, side plates 3A, 3B
A spindle 4 which inserts through is rotatably supported by a bearing (not shown). A take-up drum 5 for taking up webbing (not shown) is mounted on the outer periphery of the spindle 4 between the side plates 3A and 3B, and a ratchet wheel is provided on the spindle 4 at positions corresponding to both ends of the take-up drum 5.
6 and 6 are fitted together.

A known lock mechanism (not shown) covered with the cover 7 is disposed outside the side plate 3B. The lock mechanism detects the acceleration of the vehicle body, the webbing withdrawal acceleration, and the like to detect the side plates 3A, 3B. A stopper 6a rotatably supported by the ratchet wheel 6 is engaged with the ratchet wheels 6 and 6 so as to restrain the withdrawal of the webbing.

On the other hand, on the outer side of the lower portion of the side plate 3A, a vertically long substrate 8 extending below the side plate 3A is attached. At the lower end of the substrate 8, a small motor 9 that faces almost directly below the winding drum 5 and rotates only in one direction is attached. A rotation shaft 10 of the motor 9 faces the outside of the substrate 8. A pinion 11 is fitted on the rotating shaft 10.

An end of the spindle 4 on the side plate 3A side faces the outside of the side plate 3A so that the boss 13 of the drive shaft 12 shown in FIG. 3 can rotate integrally with the spindle 4. Is fitted to. This drive shaft
A disk 14 is provided around the tip of the boss 13 of 12 and three support pins 16, 16 are projected on the back surface 15 of the disk 14 at an angle of 120 degrees from each other. Has been done. Also, the disc 1
In front of 4, a support shaft 17 having an axial slit 17a formed at its tip is coaxially projected.

The planetary gears 18 of the planetary gear mechanism are rotatably supported by the support pins 16 and 16 of the drive shaft 12, and the planetary gears 18 are independently rotatable by the bosses 13 of the drive shaft 12. Sun gear 19 of the planetary gear mechanism being fitted
The external tooth 19a of this is engaged. A disk 20 is provided around one end of the sun gear 19, and an annular wall 22 is provided around the outer periphery of a back surface 21 of the disk 20, and the direction is reversed above the sun gear 19 in FIG. As shown, a ratchet 23 is formed on the inner peripheral side of the annular wall 22.

The boss of the drive shaft 12 adjacent to the sun gear 19
A clutch gear 24 that is independently rotatable with respect to the boss 13 is fitted to the boss 13.
An annular wall 26 surrounding the outer periphery of the disc 20 of the sun gear 19 is provided around the outer periphery of the outer gear 24, and the outer teeth 24a are provided outside the annular wall 26.
Are formed. Also, the base plate 25 of this clutch gear 24
The support pin 27 protruding toward the disk 20 side of the sun gear 19.
The support pin 27 has a pawl 28 rotatably and pivotally attached thereto. The pawl 28 engages with the ratchet 23 of the sun gear 19 to rotate the clutch gear 24 in the webbing winding direction (counterclockwise direction in FIGS. 2 and 3).
A claw portion 29 for transmitting the power to the sun gear 19 is provided in a protruding manner. Further, a projection 31 extending in the axial direction of the clutch gear 24 and facing the back of the base plate 25 through an opening 30 formed in the base plate 25 of the clutch gear 24 is provided on the claw part 29 so as to project therefrom. Further, between the protrusion 31 and the pin 32 protruding from the substrate 25,
A coil spring 33, which urges the pawl portion 29 of the pawl 28 in a direction to release the engagement of the sun gear 19 with the ratchet 23, is stretched. An inertia plate 34, which is independently rotatable with respect to the boss 13, is fitted to a boss 13 of the drive shaft 12 adjacent to the clutch gear 24. The inertia plate 34 cuts a disc with its strings. It has a shape in which it is dropped to form a flat end surface 35, and the projection 31 of the pawl 28 can be engaged with this end surface 35 as the clutch gear 24 rotates.

A sensor gear 36 is fitted to the base end portion of the sun gear 19, an annular wall 37 facing the outer peripheral side of the sun gear 19 is provided around the outer periphery of the sensor gear 36, and an inner peripheral side of the annular wall 37 is provided. Internal teeth 38 with which the planetary gears 18 mesh are formed. Further, on the inner peripheral side of the annular wall 37, an annular groove 39 is formed in which the outer peripheral edge of the disc 14 supporting each planetary gear 18 is slidably fitted, and the disc 14 is formed. By being fitted in the annular groove 39, each planet gear 18 is pulled out from the support pin 16. By being fitted in the annular groove 39, each planet gear 18 is stably supported without coming off the support pin 16. There is.

Two protrusions 40, 41 are provided on the outer peripheral side of the annular wall 37 of the sensor gear 36 at substantially diametrical intervals,
Of these, one end of a coil spring 42 for urging the sensor gear 36 in the counterclockwise direction (winding direction of the webbing) in FIG. 2 is attached to the protrusion 40, and the other end of the coil spring 42 is attached to the substrate 8. Is attached to a cover 43 which is integral with the. In addition, the annular wall 37 of the sensor gear 36 near the protrusion 40.
A notch 44 is formed in the cutout.

By the way, in the planetary gear mechanism composed of the planetary gear 18, the sun gear 19 and the sensor gear 36, the sun gear 19 is designed to be freely rotatable, and the sensor gear 36 is also attached to the webbing winding direction by the coil spring 42. Although it is energized, it can rotate freely.
Therefore, when the drive shaft 12 is rotated clockwise in FIG. 3 by pulling out the webbing and the planet gears 18 are revolved in the circumferential direction, one of the sun gear 19 and the sensor gear 36 is stationary while the other is each planet gear. Although it rotates by meshing with 18, the spring force of the coil spring 42, the sun gear 19 and the sensor gear are used in this embodiment.
Planetary gear 1 due to the difference in weight of 36 and the difference between external teeth 19a and internal teeth 38
The sensor gear 36 is rotated when the webbing is strongly pulled out due to the difference in frictional force with respect to 8, and the sun gear 19 is rotated when the webbing is pulled out weakly.

A delay plate 45 is fitted to the support shaft 17 so as to be independently rotatable with respect to the support shaft 17, and an arc-shaped long hole 46 is concentrically formed in the delay plate 45. A guide pin 47 protruding from the circular plate 14 is slidably fitted in the long hole 46. Further, an annular groove 48 is formed on the outer peripheral surface of the delay plate 45, and an annular portion 49a of a friction spring 49 composed of a wire spring is densely mounted in the annular groove 48 so as to be frictionally engaged. .

Thus, the rotation of the drive shaft 12 is delayed by the amount of play of the long hole 46, that is, the amount corresponding to a predetermined amount, so that the delay plate 45 is rotated, and the friction spring 49 is rubbed against the delay plate 45. The engaging means constitutes a holding means for holding the energized state of the switch means (first micro switch 54) described later.

The cover 43 covers the outer periphery of the delay plate 45, and the cover 43 prevents the delay plate 45 from coming off the support shaft 17. Further, the support shaft 17 extends through the cover 43 to reach the outside of the cover 43, and the outer periphery of the support shaft 17 exposed to the outside of the cover 43 is as shown in FIG. It is covered by an auxiliary cover 50 attached to the cover 43. This auxiliary cover 50
Has a circular spring receiving portion 51 located on the outer periphery of the support shaft 17. Inside the spring receiving portion 51, the inner end is held by the slit 17a of the support shaft 17 and the slack of the webbing is caused by the spindle 4. A mainspring spring 52 is provided which imparts an extremely weak winding force to the extent that the spring is pulled.

The drive force of the pinion 11 rotated by the motor 9 is applied to the base plate 8 near the motor 9 by the clutch gear.
An idle gear 53 for transmitting to the motor 24 is rotatably supported so as to mesh with the pinion 11 and the external teeth 24a, and the substrate 8 near the idle gear 53 is connected to the motor 9. A first micro switch 54, which is a switch means for stopping energization, is attached.
On the other hand, the substantially L-shaped actuating portion 49b of the friction spring 49 extends in the direction of the first micro switch 54 through the notch 44 of the sensor gear 36, as shown in detail in FIG. When the operating portion 49b contacts the actuator 55 of the first micro switch 54, the first micro switch 54 is turned off.
It is supposed to be.

As shown in FIG. 4, the cover 43 includes the friction springs.
A pair of stoppers 56A, 56B for allowing the rotation of the actuating portion 49b of 49 between a position in contact with the actuator 55 of the first micro switch 54 and a position not in contact with the actuator 55 are provided in a protruding manner. The interval of 56B is formed to be larger than the circumferential length of the notch 44 of the sensor gear 36. Further, the cover 43 has the sensor gear 36
Another pair of stoppers 57A and 57B for engaging the projection 41 of the sensor gear 36 to rotate the sensor gear 36 only within an angle substantially equal to that of the operating portion 49b of the friction spring 49 are provided in a protruding manner.
The protrusion 41 faces the space between the stoppers 57A and 57B.

Further, as shown in FIG. 5, the control circuit for controlling the drive of the motor 9 includes a fuse 59, a second micro switch 60 and the first micro switch 54 in series between the battery 58 and the motor 9. Connected and configured. Of these, the second micro switch 60 is arranged in a buckle (not shown) of the seat belt, and is turned on when the tongue inserted in the webbing is disengaged from the buckle. Therefore, the operating portion of the friction spring 49
Unless 49b contacts the actuator 55 of the first micro switch 54 to turn off the first micro switch 54,
When the tongue is separated from the buckle, the motor 9 is driven in the webbing winding direction.

Next, the operation of this embodiment having the above-described configuration will be described.

When the webbing (not shown) is completely wound around the winding drum 5, as shown in FIG. 4A, the sensor gear 36 is protruded by the action of the coil spring 42 that rotates the sensor gear 36 counterclockwise. Although 41 is in contact with the stopper 57B, the operating portion 49b of the friction spring 49 is
The notch 44 of 6 is in contact with the left side surface in the drawing, and the first
Since it is in contact with the actuator 55 of the micro switch 54, the first micro switch 54 is turned off and the motor 9 is stopped. At this time, the guide pin 47 of the disc 14 is positioned at the counterclockwise end of the elongated hole 46 of the delay plate 45.

In this state, when the passenger sits on the seat, picks up the webbing, and pulls out the webbing from the winding drum 5 against the weak tension of the mainspring 52, the spindle 4 rotates together with the winding drum 5, This rotation is transmitted from the drive shaft 12 to the planet gears 18 and the planet gears 18
Respectively revolve in the clockwise direction in FIG. Then, either one of the sun gear 19 and the sensor gear 36 selectively rotates clockwise in accordance with the pulling-out force of the webbing, and the sensor gear 36 is rotated in both directions by this pulling-out force and the spring force of the coil spring 42. By repeating this, the protrusion 41 of the sensor gear 36 moves in both directions between the stoppers 57A and 57B, and sometimes contacts the stoppers 57A and 57B. When the drive shaft 12 continues to rotate, the guide pin 47 of the drive shaft 12 moves clockwise in the elongated hole 46,
When the guide pin 47 comes into contact with the clockwise end of the long hole 46, the delay plate 45 is rotated clockwise thereafter, and the friction spring 49 frictionally engaged with the delay plate 45.
Is also rotated clockwise, the operating portion 49b contacts the stopper 56A, the friction spring 49 stops, and then the delay plate
Only 45 rotates clockwise. This state is shown in FIG. 4B. In the state of FIG. 4B, the operating portion 49b is in contact with the actuator 55 of the first micro switch 54, so that the first micro switch 54 remains OFF. .

When the webbing is pulled out from the winding drum 5 in this manner, the tongue inserted through the webbing is engaged with the buckle (not shown) to mount the seat belt. Then, the spring force of the coil spring 42 causes the sensor gear 36 to rotate counterclockwise in FIG. 4B, and the notch 44 of the sensor gear 36.
Although the friction spring 49 is also rotated in the counterclockwise direction by pushing the operating portion 49b in the direction of FIG. 4, the protrusion 41 of the sensor gear 36 abuts against the stopper 57B, and the same as in FIG. Then, with the movement of the sensor gear 36, the spring force of the delay plate 45 causes the spindle 4 and the winding drum 5 to rotate so as to wind up the extra webbing, thereby rotating the guide pin 47 in the counterclockwise direction. Then, when the guide pin 47 reaches the counterclockwise end of the elongated hole 46 of the delay plate 45, the guide pin 47 causes the delay plate 45 to rotate counterclockwise and the friction spring 49 together with the delay plate 45. Rotate the operating part 49b until it comes into contact with the stopper 56B, and move the operating part 49b to the first microswitch 5
It is separated from the actuator 55 of 4. As a result, the first micro switch 54 is turned on, but the second micro switch 60 is turned off, so the motor 9 is not driven (Fig. 4D).

When an occupant moves his / her upper body in such a seatbelt wearing state, withdrawal of the webbing is accompanied with this, and the normal withdrawal speed of the webbing is such that the sensor gear 36 is rotated clockwise. Since it is not speed, the state of FIG. 4D is maintained. By the way, in this case, since the drive shaft 12 rotates in the pull-out direction, the guide pin 47 of the disc 14 is provided with the long hole of the delay plate 45.
After rotating along 46, the delay plate 45 is rotated in the clockwise direction, the friction spring 49 also rotates in the same direction, and the operating portion 49b contacts the actuator 55 of the first micro switch 54. The first micro switch 54 is turned off. However, when the occupant returns to the original posture, the webbing is wound again by the spring force of the mainspring spring 52,
The friction spring 49 is rotated counterclockwise together with the delay plate 45 to return to the state of FIG. 4D.

Next, when the tongue is disengaged from the buckle, the second micro switch 60 is turned on, and in this state, the first micro switch 54 is also turned on, so that the motor 9 is rotationally driven. Then, the rotation of the motor 9 causes the pinion 11 to rotate.
Then, the speed is reduced via the idle gear 53 and then transmitted to the clutch gear 24, and the clutch gear 24 starts rotating in the counterclockwise direction. Then, in this state, the projection 31 of the pawl 28 supported by the clutch gear 24 is pressed against the end surface 35 of the inertia plate 34 which is stationary, and the pawl 28 rotates clockwise against the coil spring 33. The pawl portion 29 is engaged with the ratchet 23 of the sun gear 19 so that the rotation of the clutch gear 24 is transmitted to the sun gear 19, and the rotation continues together with the inertia plate 34. As a result, the rotation of the sun gear 19 is transmitted to each planet gear 18, and the planet gear 18 revolves counterclockwise to rotate the winding drum 5 in the webbing winding direction via the drive shaft 12 and the spindle 4. Since the tension of the webbing is very small until the winding of the webbing is completed, the sensor gear 36 hardly rotates and the webbing is wound while maintaining the state of FIG. 4D. When the winding of the webbing by the motor 9 is completed in this way, the tension of the webbing rapidly increases, the rotation of the winding drum 5 and the spindle 4 is stopped, and the drive shaft 12 also stops. Therefore, the sensor gear 36 rotates clockwise. As a result, the friction spring 49 fitted in the notch 44 of the sensor gear 36 also rotates clockwise, the operating portion 49b of the friction spring 49 contacts the actuator 55, the first micro switch 54 is turned off, and the motor The energization of 9 is stopped (Fig. 4E).

When the motor 9 stops, the clutch gear 24 also stops, and the inertia plate 34 also stops together with it. Therefore, the pawl 28 supported by the clutch gear 24 moves the pawl portion 29 of the sun gear 19 against the ratchet 23 by the spring force of the coil spring 33. The engagement is released. As a result, the sensor gear 36 in which the torque of the motor 9 has been released is rotated counterclockwise by the action of the coil spring 42, returns to the state shown in FIG. 4A, and the winding of the webbing is completed.

If the webbing catches on the body or body of the occupant and stops during the winding of the webbing, in this case as well, FIG.
However, when the cause of the webbing catching is eliminated, the spring spring 52 causes the webbing to be slightly wound up and the state shown in FIGS. 4A to 4D is reached. 9 restarts the rotational driving to wind up the webbing, and the state shown in FIGS. 4E to 4A is reached, and the winding of the webbing is completed.

As described above, according to this embodiment, when the seat belt is worn, the body of the occupant is tightened only to the extent that the looseness of the webbing is removed by the spring spring 52 having a weak tension.
The occupants have little pressure. When the buckle is disengaged, the webbing is wound by the motor 9. The webbing is continuously wound by the motor 9 until the webbing is completely wound up and the tension of the webbing increases. It can be done reliably. Further, if the webbing is caught, the tension of the webbing increases, and the rotation of the sensor gear 36 causes
Even if the first micro switch 54 is turned off, if the hooking of the webbing is released, the spindle 4 and the take-up drum 5 are rotated by the tension of the mainspring 52, and at this time, the planet gears 18 revolve and the sensor gear 36 is rotated. Rotates to turn ON the first micro switch 54 again.

In this way, the webbing is wound up again by the motor 9, so that no special operation is required. Furthermore,
Since the motor 9 is used only for winding the webbing, it is sufficient to use a small and inexpensive motor.

Further, the pawl portion 29 of the pawl 28 is an inertial clutch that engages with the ratchet of the sun gear 19 only when the webbing is wound by the motor 9, so that the webbing can be wound and pulled out without using the motor 9, unlike a one-way clutch. At that time, there is no possibility that the pawl 28 is always engaged with the ratchet 23 and an unpleasant contact sound is generated.

Furthermore, the holding means acts so that the sensor gear 36 rotates the friction spring 49 only when the guide pin 47 moves by a predetermined amount along the elongated hole 46 and then the webbing is wound by a predetermined amount or more. There is no possibility of a so-called hiccup phenomenon in which the ON / OFF of a certain first micro switch 54 is repeated and the ON / OFF of the motor 9 is repeated.

[Effect of device]

As described above, according to the present invention, the winding of the webbing by the motor can be reliably performed until the winding of the webbing is completed by only the operation of disengaging the buckle.

Further, since it has a tension detecting means for detecting the tension acting on the webbing, and a switch means for stopping the energization of the motor when the tension of the webbing detected by the tension detecting means exceeds a predetermined value, The motor is not overloaded.

Further, when the seat belt is worn, the motor is turned on when the seat belt is worn because the holding means holds the energized state of the motor by the switch means when the webbing is not wound by the spring means by more than a predetermined amount. The hiccup phenomenon that repeats OFF is also eliminated.

Furthermore, the inertia clutch supports the pawl capable of engaging the ratchet of the sun gear with the clutch gear to which the rotation of the motor is transmitted, and the inertia that rotates following the pawl to engage the pawl with the ratchet. If the plate is provided, the ratchet does not generate any unpleasant noise.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a seat belt retractor according to the present invention, FIG. 2 is a left side view in which a part of FIG. 1 is cut away, and FIG. 3 is a view of FIG. 1 and FIG. FIG. 4 is an exploded perspective view of the essential part of the retractor, FIGS. 4A, B, C, D and E are schematic front views showing the action of the retractor, and FIG. 5 is a control circuit diagram of the motor. 1 ... Retractor body, 2 ... Substrate, 3A, 3B ... Side plate, 4 ...
Spindle, 5 ... Winding drum, 8 ... Substrate, 9 ... Motor, 12 ... Drive shaft, 18 ... Planetary gear, 19 ... Sun gear, 24 ... Clutch gear, 28 ... Pawl, 29 ... Claw portion, 31 ... Projection, 36 ... Sensor gear, 45 ... Delay plate, 46 ... Oblong hole, 47 ... Guide pin, 49 ... Friction spring, 52 ... Mainspring spring, 54 ... First micro switch, 60 ... Second micro switch.

Claims (4)

[Scope of utility model registration request] 1. Spring means connected to a spindle for supporting a take-up drum of a webbing, for constantly applying a spring force to the spindle to a degree capable of removing looseness of the webbing.
A detection means for detecting disengagement of the tongue from the buckle for mounting the webbing on an occupant, and a motor driven by a buckle dissociation signal from the detection means to rotate the spindle in the webbing winding direction via an inertial clutch. A tension detecting means for detecting tension acting on the webbing, a switch means for stopping energization of the motor when the tension of the webbing detected by the tension detecting means exceeds a predetermined value, and the spring means. Only when the winding amount of the webbing exceeds a predetermined amount, the switch means is switched by the winding of the webbing, and when the winding amount of the webbing above the predetermined amount does not occur, the motor is energized by the switch device. Retractor of seat belt having holding means for holding a stopped state Over. 2. The tension detecting means includes a sun gear that rotates when the motor is wound, a planet gear that meshes with the sun gear and is rotatably supported on a disc that rotates together with the spindle, and meshes with the planet gear. A sensor gear that has internal teeth that are rotatable about the rotation axis of the sun gear,
The seat belt retractor according to claim 1, characterized in that it comprises a spring member for urging the sensor gear to rotate in one direction. 3. The holding means has a circular plate which is rotatably coaxially supported by the circular plate of the tension detecting means and has a circular arc-shaped opening formed in one of which is fitted with a pin protruding from the other end. The seat belt retractor according to claim 2, characterized in that it comprises a delay plate to which only a rotation of an angle or more is transmitted, and a substantially annular friction spring fitted to the delay plate. . 4. A ratchet is formed on the sun gear,
The inertia clutch supports a pawl capable of engaging with a ratchet of a sun gear in a clutch gear to which rotation of a motor is transmitted, and an inertia plate that follows the rotation of the pawl and rotates the pawl so as to engage with the ratchet. The seat belt retractor according to claim 2 or 3, characterized in that the retractor is provided with.