JPH10167003A - Seatbelt retractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seatbelt retractor with a pretensioner which can be operated repeatedly. SOLUTION: A driven gear 203 provided on a reel 20 is rotated by an ultrasonic motor 224 in a pretension giving direction through a motive gear 201 and an intermediate gear 202. When the ultrasonic motor 224 is rotated normally, a support plate 230 is rotated normally and mashed with gears 202, 203. When the ultrasonic motor 224 is rotated reversely, the gear 202 is separated from the gear 203. The support plate 230 can be rotated by range between the stoppers 246, 248.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a retractor for a seat belt device provided in a vehicle for protecting an occupant. More specifically, the present invention relates to a pretensioner configured such that the seat belt softly contacts the occupant when the occupant wears the seat belt, and the seat belt is strongly wound up when the vehicle encounters an emergency. The present invention relates to a seat belt retractor having a mechanism.

[0002]

2. Description of the Related Art In a seat belt device with a pretensioner, when a collision of a vehicle is detected, the pretensioner rapidly winds up the seat belt by a predetermined length and strongly restrains an occupant with the seat belt.

In this pretensioner, a driven shaft protruded from a reel of the seat belt device is driven to rotate by a driving device, thereby rotating the reel of the seat belt device in a seat belt winding direction.

The pretensioner must not prevent the reel from freely rotating when the vehicle is in a normal state. The pretensioner is provided between the driven shaft and the pretensioner driving device only when a vehicle collision is detected. A clutch mechanism for transmitting the driving force from the driving device to the driven shaft is provided.

[0005] As the above-mentioned driving device, there is a driving device which detects the occurrence of a collision, ignites an explosive, and generates a rotational torque by the generated gas pressure (for example, US Patent No. 5,451,008, Germany). Patent Publication No. 4,44
No. 4,775, No. Hei 7-5992).

[0006] A driving device using a spiral spring as a power source is also known (Japanese Patent Application Laid-Open No. Sho 59-168860).

In the above clutch mechanism, a cylindrical rotor is disposed around a reel shaft, and a cylindrical pin is interposed between an outer peripheral surface of the reel shaft and an inner peripheral surface of the rotor. The pin is pressed against the outer peripheral surface of the shaft by a slope provided on the inner peripheral surface of the rotor when the rotor is rotationally driven (U.S. Pat. Nos. 4,750,685 and 4,423,846).
issue).

[0008]

In the case of using an explosive as a driving power source of the pretensioner, the pretensioner has one
The disadvantage is that it cannot be reused once it has been turned.

[0009] In the apparatus using a mainspring as a power source as disclosed in JP-A-59-168860, when the pretensioner operates, it can be returned to an initial state using a tool such as a wrench and reused. (Lower left column on page 6 of the same publication).

However, in order to perform this return operation, it is necessary to take out the seat belt retractor from the vehicle, which is quite inconvenient.

An object of the present invention is to provide a seat belt retractor that can repeatedly apply pretension.

It is another object of the present invention to provide a seat belt retractor which allows a seat belt to be fitted to an occupant without loosening and has a sufficiently small feeling of pressure on the occupant.

[0013]

According to the present invention, there is provided a seat belt retractor comprising: a reel for winding a seat belt;
One end is connected to the reel, and a winding spring for urging the reel in a seat belt winding direction so that the seat belt can be wound, and the reel is rotated to tighten the seat belt. A motor, a clutch device for intermittently transmitting the driving force of the motor to the reel, a collision prediction device for predicting a vehicle collision, and a seat belt tightening direction based on a signal from the collision prediction device. And control means for causing the rotation to occur.

In such a seat belt retractor, when a collision of a vehicle is predicted, a pre-tension is applied by rotating a reel in a seat belt tightening direction by a motor. When the possibility of collision is eliminated, the pretension can be released by rotating the motor in the reverse direction. Therefore, pre-tension can be repeatedly applied.

When an ultrasonic motor is used as the motor, the operating noise is low. Further, since the driving torque during operation is large, a strong pretension can be obtained. Since the stop torque of the ultrasonic motor is extremely large, a member for holding the stopped state is unnecessary.

According to the present invention, the clutch device comprises a driving shaft rotated by the ultrasonic motor, a driving gear mounted on the driving shaft, a driven gear mounted on the reel, and a supporter mounted on the driving shaft. A support plate rotatable about the axis of the drive shaft, and a sliding member slidably in contact with at least one of the two so as to transmit the rotational force of the ultrasonic motor to the support plate. And is rotatably attached to the support plate, and is always meshed with the driving gear. With respect to the driven gear, the support plate is rotated with the rotation of the ultrasonic motor in the tightening direction. When the support plate rotates in the opposite direction with the rotation of the ultrasonic motor in the opposite direction, the intermediate gear separates from the driven gear. The range of rotation of the support plate, it is preferable that the distance between the intermediate gear and the driven gear is made of a rotation range restricting member are regulated to be within a predetermined.

In this case, a housing surrounding each gear is provided, and the rotation range regulating member is provided in the housing, and a stopper portion which comes into contact when the support plate rotates in the opposite direction. Preferably.

According to the present invention, the other end of the spring is connected, and a movable member movable in a direction for changing the urging force of the spring; an ultrasonic motor for moving the movable member to change the urging force; An urging force detecting means for detecting an urging force generated by the spring; and a means for controlling the urging force by moving the movable member by the ultrasonic motor so that the urging force detected by the urging force detecting means becomes a target value. Power control means.

In such a seat belt retractor, the urging force of the spring is detected, and the urging force is controlled so that the urging force becomes a target value. Therefore, the seat belt is fitted to the occupant without slack, and the seat belt is compressed. The feeling can be made sufficiently small.

In the present invention, tongs may be provided a tongue engagement detecting means for detecting that engaged with the buckle, the biasing force of the spring when the seat belt storage and T _1, after the seat belt withdrawing, tongue buckle the biasing force of the spring until it engages with the smaller T ₂ than T _1, after the tongue is engaged with the buckle, once the urging force of the spring and higher T ₃ than T _2, then, the biasing force and lower T ₄ than T _3, when the tongue becomes disengaged with respect to the buckle, the sheet to the belt storage completion, preferably the urging force and high T ₅ than either T ₁ and T _3.

[0021]

1 to 4 are exploded perspective views of a seat belt retractor according to an embodiment of the present invention.
FIG. 5 is a sectional view of the seat belt retractor, FIG. 6 is an explanatory diagram of the operation of the seat belt retractor, FIG. 7 is a spring characteristic diagram of the spring, and FIG. 8 is a control block diagram. FIG. 2 is an enlarged view of the pretensioner mechanism of FIG. 1, and FIG. 3 is an enlarged view of the lock mechanism of FIG.

The frame 10 has a pair of parallel side walls 12,
14 and a back plate portion 16 connecting these side wall portions 12 and 14 to each other.
And In this frame 10, the seat belt 1
A reel 20 for winding the reel 8 is provided. The reel 20 is inserted into the openings 12a and 14a of the side wall portions 12 and 14.

An emergency lock mechanism 22 for the reel 20 is provided outside the side wall portion 14. The side wall 12
A spring mechanism 26 for urging the reel 20 in the seat belt winding direction is provided on the outside of the vehicle, and a first ultrasonic motor 24 for adjusting the urging force is provided on the outside thereof. A pretensioner mechanism 200 is provided below the spring mechanism 26.

First, the spring mechanism 26 will be described.

The spring mechanism 26 includes a spring 32 for urging the reel 20 in the seat belt winding direction, a housing 33 surrounding the spring 32, and a spring case 34. The spring 32 is formed of a spiral spring (spring spring). The center end of the spring 32 is fixed to the reel shaft 31 (FIG. 5) via a bush 35, and the outer peripheral end is locked by a hook portion 34 a on the inner peripheral surface of the spring case 34.

The housing 33 is provided on the side wall 1 of the frame 10.
2, the spring case 34 has its annular peripheral wall 34b slidably fitted in the housing 33.

A hexagonal case shaft 34 c protrudes from the outer surface of the spring case 34 coaxially with the reel 20. The case shaft 34c is inserted into a hexagonal shaft hole 36 penetrated by the rotor of the ultrasonic motor 24. The input shaft 37a of the rotary encoder 37 is engaged with the tip of the case shaft 34c.

The inner peripheral side 32a of the spring 32 has a larger spring constant than the outer peripheral side 32b.
Therefore, when the seat belt 18 is pulled out from the reel 20, the outer peripheral side 32b having a small spring constant is first tightened, and then the inner peripheral side 32a having a large spring constant is also tightened.

[0029] Incidentally, when the seat belt 18 is pulled out, the reel 20 is rotated in the arrow A ₁ direction, when winding the seat belt 18 rotates in the arrow A ₂ direction.

As shown in FIG. 5, the ultrasonic motor 24 includes a piezoelectric element array 110 and a piezoelectric element array 11 arranged in a circle.
Annular stator 112 installed in a state of being substantially in contact with zero
And a circular rotor 114 at the center of which is fitted with the case shaft 34c.

The rotor 114 has a disk-shaped annular spring 1.
The urging force of 16 presses the annular stator 112.

When the piezoelectric element array 110 is not energized, the circular rotor 114 is stopped by being strongly pressed against the annular stator 112 by the spring 116, and the case shaft 34 c is connected to the annular stator 112 via the circular rotor 114. Then, the rotation is stopped. That is, when the piezoelectric element row 110 is not energized, the spring case 34 cannot rotate.

When an ultrasonic signal is applied to the annular piezoelectric element array 110, the annular piezoelectric element array 110 is distorted in a wave shape in accordance with the ultrasonic signal, and the rotor 11 is rotated via the stator 112.
Rotate 4.

The amount of rotation of the spring case 34 accompanying the rotation of the rotor 114 is detected by the rotary encoder 37. This detection signal is transmitted to the control unit 120 (eighth) together with the detection signal of the rotary encoder 107 described later.
Figure). The control unit 120 also receives signals from a buckle switch 122 and an inter-vehicle distance sensor 124. The control unit 120 controls the operation of the ultrasonic motors 24 and 224 based on these signals.

Next, the pretensioner mechanism 200 and its associated clutch mechanism will be described with reference to FIGS.

The housing 33 is provided on the frame side wall 1.
2 extends in the vertical direction along the outer surface of the second. In this housing 33, a housing 211 for the driving gear 201, a housing 212 for the intermediate gear 202, and a housing 2 for the driven gear 203.
13 are provided. The driven gear 203 is fixed to the reel 203.

The driving gear 201 is fixed to the tip end of a hexagonal shaft (driving shaft) 220.
The rear end side of 20 is inserted into the hexagonal shaft hole 222 of the second ultrasonic motor 224.

The tip of the shaft 220 has a circular shaft portion 22.
6 and a male screw 228 are provided.
6, a circular hub hole 232 of the support plate 230 is rotatably fitted. Hub hole 2 of this support plate 230
32 is fitted to the circular shaft portion 226 of the shaft 220, a disc spring (sliding member) 234 is fitted to the shaft 220, and then a nut 236 is screwed into the male screw 228 of the shaft 220, 234 is the support plate 2
Pressed to 30.

Note that the support plate 230 is
The screw 36 is slidably pressed against the driving gear 201.

The support plate 230 extends in the up and down direction, and the intermediate gear 2 is inserted into a hole 238 provided on the support plate 230.
02 support shaft 240 is rotatably engaged.

The lower end of the support plate 230 is bent into an L shape to form a protruding piece 242. This protruding piece 242 is
The housing 33 is disposed in a concave portion 244 provided at the bottom of the driving gear housing portion 211. This recess 24
Numeral 4 extends along the peripheral edge of the housing portion 211, and both ends in the circumferential direction are stopper portions (rotation range regulating members) 246 and 248 with which the protruding pieces 242 abut.

[0042] When the second ultrasonic motor 224 is rotated in the D ₂ direction, the driving gear 201 is also rotated in the D ₂ direction, the support plate 230 is also rotated in the D ₂ direction. Support plate 23
0 rotates until the protruding piece 242 contacts the stopper portion 248. Even rotate the ultrasonic motor 224 is more D ₂ direction, the support plate 230 slides with the driving gear 201 and the disc spring 234 does not rotate more D in _two directions.

When the protruding piece 242 is in contact with the stopper 248, as shown in FIG.
Meshes with the driven gear 203 and the second ultrasonic motor 224
The rotational force of the D ₂ direction is transmitted to the reel 20 via the gear 201, 202, the reel 20 is rotated in the A ₂ direction, the seat belt 18 is wound.

[0044] When the ultrasonic motor 224 in the meshing state of the gears 202 and 203 in the FIG. 6 (a) is rotated in D ₁ direction, the driving gear 201 and the support plate 203 is D ₁
Rotate in the direction. The seat belt 230 is shown in FIG.
, The projection 242 rotates until the projection 242 contacts the stopper 246. By the seat belt 230 is rotated in the D ₁ direction, away intermediate gear 202 from the driven gear 203,
The clutch becomes free. In this state, the reel 2
0 is freely rotatable from the second ultrasonic motor 224.

Next, the structure of the lock mechanism 22 will be described with reference to FIGS.

A ratchet wheel 38 coaxial with the reel 20 is fixed to the other end of the reel 20. The reel shaft 40 penetrates the ratchet wheel 38 and the reel shaft 40
It protrudes coaxially with zero. This reel shaft 40
At the base side is a large-diameter circular shaft portion 40a, and a square shaft portion 40b is formed adjacent to the circular shaft portion 40a. The circular shaft portion 40a has an opening 4 of a tie plate 42.
3 and the center hole 48 of the lock ring 44 are fitted.

The tie plate 42 supports one end of a C-shaped spring 50 described below. The opening 43 is provided on the tip side of the tie plate 42, and an opening 64 described later is provided on the other end side. The rear end of the tie plate 42 is supported by the frame side wall portion 14 by the shaft pin 60 inserted into the opening 64. That is, the tie plate 42 is provided between the projecting portion 40 and the shaft pin 60.

One end 50a of the C-shaped spring 50 is locked in a locking hole (spring hanger) 52 provided substantially in the center of the tie plate 42, and the other end is locked in a locking ring 44 (spring hanger). 54. The spring hanger 5 extends around the shaft 40.
A biasing force is applied to the lock ring 44 in the direction of the arrow A2 by the spring 50 provided between the _{second and the second} 54.

The lock ring 44 is provided with internal teeth 56.

The pawl 5 is provided on the side wall 14 of the frame 10.
8 has a shaft pin 60 inserted through its opening 58a.
It is pivoted by The tip of the pawl 58 can engage with teeth on the outer peripheral surface of the ratchet wheel 38. A protruding pin 62 protrudes from a middle portion of the pawl 58. As described above, the opening 64 on the tip side of the tie plate 42 is also fitted to the shaft pin 60. This shaft pin 60 is
It is attached to the hole 65 of the frame side wall portion 14.

The lock ring 44 is integrally provided with a projecting portion 66 projecting radially. This overhang 66
Wherein the pawl 58 is intended for turning in the C ₁ direction, the overhung portion 66, arcuate long hole 70 extending in the constant radius position with respect to the central hole 48 is provided, the length The protruding pin 62 of the pawl 58 is inserted into the hole 70.

The square shaft portion 40b of the reel shaft 40 which penetrates through the center hole 48 of the lock ring 44 and projects outside thereof
A central square hole 72a of the hook retainer 72 is fitted into the hook retainer 72. Protrusions 76 and 78 for supporting the hook 74 are provided on the periphery of the hook retainer 72 so as to face each other in the diametrical direction. A hook 74 is attached to the projections 76 and 78.
The hooks 74 are supported by the hook retainer 72 so as to be able to linearly reciprocate in the direction (B ₁ , B ₂ directions) connecting the projections 76, 78.

[0053] The spring engaging portion 72b of the hook retainer 72 and the hook 74, between 74b are compression coil spring 84 is interposed, the hook 74 is biased in the arrow B ₁ direction. A hook 86 is provided at a part of the outer peripheral edge of the hook 74 so as to be able to engage with the internal teeth 56 of the lock ring 44. A connecting pin 88 is provided on the outer surface of the hook 74.

[0054] hook 74, in the normal state, takes the position shifted in the arrow B ₁ direction by being biased in the compression coil spring 84, as a result, the pawl 86 is disengaged from the internal teeth 56 I have.

The connection pin 88 is fitted with a locking hole 92 provided in the vicinity of the outer peripheral edge of the disc-shaped flywheel 90. A gear ring 96 having external teeth is fitted around the entire circumference of the flywheel 90. A bent end portion 98a of an arc-shaped spring 98 is mounted on a cutout portion 90a on the outer peripheral edge of the flywheel 90, and the spring 98 is slidably pressed against the inner peripheral surface of the gear ring 96. The gear ring 96 is slidable and rotatable while receiving a frictional force against the flywheel 90.

An acceleration sensor 100 having a lever 102 which engages with teeth on the outer peripheral surface of the gear ring 96 is attached to the frame side wall portion 14. The acceleration sensor 100 has a tiltable weight 104 accommodated in a sensor case 103 and a lever 102 rotatably mounted on the upper part of the sensor case 103.

When an acceleration equal to or more than a predetermined value is applied to the weight 104, the weight 104 tilts, and the weight 10
The lever 102, which has overlapped with No. 4, is pushed upward,
The tip of the lever 102 engages with the gear ring 96. If the seat belt 18 is about to be pulled out in this state,
The rotation of the reel 20 is stopped as follows.

[0058] When the reel 20 attempts to rotate, the hook retainer 72 engaged with the square shaft portion 40a of the square of the reel 20 is rotated in A ₁ direction of the first and second views. At this time,
Projections 76 and 78 of the hook retainer 72 to rotate in the arrow A ₁ direction together with the hooks 74 also hook retainer 72 engaging the holes 80 and 82. However, the hook 74
The rotation of the flywheel 90 with which the pin 88 is engaged is stopped (that is, the flywheel 90 is stopped because the arcuate spring 98 is pressed against the stopped gear ring 96). the hook 74 can not rotate as it is, only the hook 74 min the hook retainer 72 is rotated in the a ₁ direction is slid in the arrow B ₂ direction, the pawl 86 is engaged with the internal teeth 56 of the lock ring 44 .

[0059] The results are to rotate in the arrow A ₁ direction to the lock ring 44 via the hook retainer 72 and the hook 74 is also dragged in rotation of the reel 20. Then, the projecting portion 66 of the lock ring 44 also rotates in the A ₁ direction, the pawl 58 having a pin 62 engaged with the long hole 70 of the overhung portion 66 is rotated in the arrow C ₁ direction. Thereby, the tip of the pawl 58 is engaged with the ratchet wheel 38 of the reel 20, the reel 20 is firmly locked, and the seat belt 18 is prevented from being pulled out.

The emergency lock mechanism 22 is
The cover 106 is covered with the frame side wall 1.
4 attached.

A rotary encoder 107 is provided outside the cover 106. The input shaft 107a of the rotary encoder 107 is engaged with a concave hole 40d at the tip of the reel shaft 40.

In the thus constructed seat belt retractor, the intermediate gear 202 is separated from the driven gear 203 when the seat belt 18 is not pulled out. Further, the spring case 34 is stopped at a position where the urging force of the spring 32 is generated such that the seat belt 18 is not pulled out by the weight of the tongue.

When the pullout of the seat belt 18 is detected by the rotary encoder 107, the ultrasonic motor 2
4 rotates the spring 34 so as to weaken the spring force. This state where the spring force is weak is maintained until the seat belt 18 is pulled out from the seat belt retractor and the tongue is attached to the buckle.

Therefore, the vehicle occupant receives almost no resistance when pulling out the seat belt 18 from the seat belt retractor, and the seat belt 1
8 can be pulled out.

The amount of pulling out of the seat belt 18 at this time is determined by the rotary encoder 107 on the reel 20.
Is detected as the rotation amount.

When the tongue is mounted on the buckle and the buckle switch 122 is turned on, the ultrasonic motor 24 rotates the spring case 34 a predetermined number of times in the direction of tightening the spring 32 to increase the winding force of the spring 32.

As a result, the looseness of the seat belt 18 is removed, and the seat belt 18 fits perfectly to the occupant.

In this state, there is a strong sense of pressure on the occupants,
Next, the spring case 34 is driven by the ultrasonic motor 24.
Is rotated a predetermined number of times in the direction in which the spring 32 is loosened.
Thereby, the tension of the seat belt 18 decreases,
The feeling of pressure is reduced or eliminated.

When the buckle switch 122 is turned off, the ultrasonic motor 24 rotates the spring case 34 in the direction of tightening the spring 32. Thereby, the reel 20 rotates strongly and rapidly, and the seat belt 18 is rapidly wound up.

FIG. 5 is a correlation diagram between the torque applied to the reel 20 by the spring 32 used in this embodiment and the amount of rotation of the spring case 34. The horizontal axis represents the amount of rotation of the spring case 34 (unit). : Number of times), and the vertical axis indicates torque.

As described above, the spring 32 is connected to the inner circumferential side 32.
a has a higher spring constant than the outer peripheral side 32b. When the spring case 34 you turn the seat belt winding direction (A ₂ direction), although initially tightened weak portion of the spring 32 (32 b) is wound, the torque is not significantly increased even if progress is tight winding at this time .

When the spring case 34 rotates about nine times, the strong portion (32a) of the spring 32 thereafter
Is also tightened, and the torque rapidly increases with an increase in the amount of rotation of the spring case 34. If the rotation amount of the spring case 34 exceeds 12 times, the strong portion 32
Since the tightening of a becomes complete, the increase in the torque becomes slow. When the spring case 34 rotates about 26 times, the whole of the spring 32 is tightly wound, and the torque increases extremely sharply with the rotation of the spring case 34.

In this embodiment, when the seat belt 18 is retracted in the retractor, a relatively high torque near the zone B in FIG. 5 is applied to prevent the tongs from coming out by its own weight. the spring case 32 so as to obtain keep a state of being rotated about 10-11 times the a ₂ direction. That is, keep the ultrasonic motor 24 as detected rotation amount of the rotary encoder 37 is about 11 turns from 10 rotates in the A ₂ direction and then is stopped in this state.

When the occupant starts pulling out the seat belt 18, the rotary encoder 107 on the reel 20 detects that the seat belt has been pulled out. Therefore, the ultrasonic motor 24
The rotated about 3-5 turns A ₁ direction, torque is made to be weak in the vicinity A zone of Figure 5. This allows the occupant to pull out the seat belt 18 lightly and smoothly.

[0075] After pulling out the seat belt 18, the engagement of the tongue into the buckle, the ultrasonic motor 24 so that the torque is near B zone rotates the spring 32 to the A ₂ direction, the tension of the seat belt 18 Raising the seat belt 18 removes the slack, and fits the seat belt 18 to the occupant. Once holding torque to B zone, is again rotating the ultrasonic motor 24 is spring 32 so that the torque becomes A zone A ₁ direction.

[0076] Then, when the tongue from the buckle is dissociated, the ultrasonic motor 24 so that the torque becomes the C zone rotates the spring case 34 in the A ₂ direction. Thereby, the seat belt 18 is strongly and quickly wound up.
When the rotation amount of the reel 20 detected by the rotary encoder 107 becomes a value indicating the completion of the seat belt winding,
Torque ultrasonic motor 24 so that the B zone rotates the spring case 34 in A ₁ direction.

By the way, pull out the seat belt 18 and
The tongue is engaged with the buckle, and then the seat belt 18
In a state where the slack is removed from the vehicle and the tension of the seat belt 18 is reduced (standard wearing state), a collision occurs based on the following distance signal from the following distance sensor 124 (and the approach speed obtained by differentiating the following distance with respect to time). If predicted, the control unit 120 rotates the _second ultrasonic motor 224 a predetermined number of times in the direction D2. As a result, the intermediate gear 202 meshes with the driven gear 203, and the ultrasonic motor 224
Is transmitted to the reel 20, the reel 20 rotates a predetermined number of times, the seat belt 18 is wound up to a required length (usually about 60 to 150 mm, particularly about 80 to 120 mm), and the occupant is strongly restrained. Thus, when the vehicle collides, the occupant is strongly restrained by the seat belt.

When it is determined from the inter-vehicle distance signal from the inter-vehicle distance sensor 124 and the approach speed that the possibility of collision has been resolved, the ultrasonic motor 224 rotates a predetermined number of times in the direction D _{1 to} move the intermediate gear 202 to the driven gear 203. Away from In the ultrasonic motor 224, the protrusion 242 is
After contacting 46, it stops.

As described above, each time a collision of a vehicle is predicted, the ultrasonic motor 224 is operated to strongly restrain the occupant. When the danger of the collision is eliminated, the ultrasonic motor 224 is inverted to reverse the strong restraint. Because I am trying to cancel,
The pretensioner mechanism can be operated repeatedly.

In the present invention, a conventional pretensioner using explosives as a power generation source may be used in combination. In this case, when an actual collision occurs when the inter-vehicle distance sensor 124 does not predict the collision, the explosive type pretensioner is activated, the inter-vehicle distance sensor 124 detects the collision, and the second ultrasonic motor 224 When the pretension is applied to the seat belt 18, the explosive pretensioner is not operated even if the collision actually occurs.

[0081]

As described above, according to the present invention, the pretensioner mechanism can be repeatedly operated. By driving this pretensioner mechanism with an ultrasonic motor, noise during operation can be reduced. Further, since the stop torque when the ultrasonic motor is not energized is large, an extra mechanism for holding the clutch in the clutch free state is not required.

In the present invention, by rotating the spring case by the ultrasonic motor, the seat belt can be pulled out lightly when the seat belt is pulled out. When the tongue is released from the buckle thereafter, the seat belt can be strongly and quickly wound up. In this case, since the spring case is rotated by the high-torque ultrasonic motor, a speed reduction mechanism such as a gear train is not required, and the operating noise during rotation of the spring case is extremely small. Further, since the stop torque when the power is not supplied to the ultrasonic motor is large, an extra stopper mechanism for stopping the spring case is unnecessary.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a seat belt retractor according to the present invention.

FIG. 2 is an enlarged view of the pretensioner mechanism of FIG.

FIG. 3 is an enlarged view of the lock mechanism of FIG.

FIG. 4 is a perspective view of the seat belt retractor according to the present invention.

FIG. 5 is a sectional view of the seat belt retractor according to the present invention.

FIG. 6 is an operation explanatory view of the seat belt retractor according to the present invention.

FIG. 7 is a characteristic diagram of a spring used in the present invention.

FIG. 8 is a control block diagram according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Frame 12,14 Side wall part 20 Reel 24 First ultrasonic motor 26 Spring mechanism 30 Second reel shaft 32 Spring 33 Housing 34 Spring case 34c Case shaft 36 Shaft hole 37 Rotary encoder 40 First reel shaft 42 Tie plate 44 Lock Ring 58 Paul 66 Overhang 72 Hook Retainer 74 Hook 76, 78 Projection 80, 82 Hole 90 Gear Ring 104 Convex 107 Rotary Encoder 110 Piezoelectric Element Row 112 Annular Stator 120 Control Unit 122 Buckle Switch 124 Vehicle Distance Sensor 200 Pre Tensioner mechanism 201 Drive gear 202 Intermediate gear 203 Driven gear 211, 212, 213 Housing 220 Shaft (drive shaft) 224 Second ultrasonic motor 230 support plate 234 disc spring (a sliding member) 242 protruding piece 244 recesses 246, 248 stopper portion (rotation range restricting member)

Claims (8)

[Claims] 1. A reel for winding up a seat belt, one end of which is connected to the reel, the winding reel for urging the reel in a seat belt winding direction so as to wind up the seat belt. A spring, a motor for rotating the reel to tighten the seat belt, a clutch device for intermittently transmitting the driving force of the motor to and from the reel, a collision prediction device for predicting a vehicle collision, and the collision Control means for rotating the motor in the seat belt tightening direction based on a signal from the prediction device. 2. The seat belt retractor according to claim 1, wherein said motor is an ultrasonic motor. 3. The clutch device according to claim 1, wherein the clutch device comprises: a driving shaft rotated by the ultrasonic motor; a driving gear mounted on the driving shaft; and a driven gear mounted on the reel. A support plate supported by the driving shaft and rotatable about the axis of the driving shaft; and slidably contacting at least one of the two so as to transmit the rotational force of the ultrasonic motor to the support plate. A sliding member that is rotatably attached to the support plate, always meshes with the driving gear, and rotates the driven gear in the tightening direction of the ultrasonic motor. When the support plate rotates in the same direction, the gears mesh with each other, and
An intermediate gear separated from the driven gear when the support plate rotates in the opposite direction with the rotation of the ultrasonic motor in the opposite direction; and a rotation range of the support plate, the intermediate gear and the driven gear. A rotation range restricting member that restricts the distance between the seat belt and the seat belt to be within a predetermined range. 4. The housing according to claim 3, further comprising a housing surrounding the gears, wherein the rotation range regulating member is provided in the housing, and when the support plate rotates in the opposite direction. A seat belt retractor comprising a stopper portion that abuts. 5. The movable member according to claim 1, further comprising: a movable member to which the other end of the spring is connected, the movable member being movable in a direction for changing the biasing force of the spring; An ultrasonic motor for adjusting an urging force different from the ultrasonic motor that changes the urging force by moving, an urging force detecting means for detecting an urging force generated by the spring, and an urging force detected by the urging force detecting means A biasing force control means for controlling the biasing force by moving the movable member by the biasing force adjusting ultrasonic motor so that the target value becomes a target value. 6. The seat belt according to claim 5, wherein the movable member is a spring case surrounding a spring, and the spring case is rotatable around an axis of the reel. Retractor. 7. The device according to claim 6, wherein the urging force detecting means detects a rotation amount of the reel, a means for detecting a rotation amount of the spring case, and a difference between the detected rotation amounts. Means for calculating an urging force. 8. The device according to claim 7, further comprising tongue engagement detecting means for detecting that the tongue has engaged with the buckle, wherein the urging force control means includes a urging force of a spring when the seat belt is retracted. was a T _1, after the seat belt withdrawing, the urging force of the spring until tongue engages the buckle T
₁ and small T ₂ than, after the tongue is engaged with the buckle, once the urging force of the spring and higher T ₃ than T _2, then the biasing force and low T ₄ than T _3, tongue buckle Is disengaged.
Seat to the belt storage completion, the seat belt retractor, characterized in that the biasing force higher T ₅ than either T ₁ and T _3.