JP7182099B2 - seat belt retractor - Google Patents

Description

The present invention relates to seat belt retractors.

Conventionally, a spool for winding a seat belt, a locking mechanism that normally rotates together with the spool and has a locking member that prevents the rotation of the spool in the seat belt withdrawal direction during operation, and a power that rotates the spool. A seatbelt retractor is known that includes a motor that generates the force and a power transmission mechanism that transmits the power of the motor to the spool (see, for example, Patent Document 1).

JP-A-2005-88838

However, in the conventional seat belt retractor, the connected state between the rotating shaft of the spool and the output shaft of the motor is maintained until the load torque in the belt withdrawing direction reaches or exceeds a set value. When the rotating shaft of the spool and the output shaft of the motor are connected, when the passenger pulls out the seat belt from the retractor or causes the seat belt to be retracted by the retractor, the load of the motor is transmitted to the passenger operating the seat belt. put away. As a result, the occupant cannot pull out or wind up the seat belt smoothly, which may cause discomfort to the occupant.

Accordingly, the present disclosure provides a seat belt retractor that enables the occupant to smoothly pull out or retract the seat belt.

This disclosure is
a spool for winding the seat belt;
a lock mechanism having a locking member that normally rotates together with the spool and prevents the spool from rotating in the seat belt withdrawal direction during operation;
a motor that generates power to rotate the spool;
a power transmission mechanism disposed on the same side of the spool as the lock mechanism and transmitting power of the motor to the spool ;
A rotating body that rotates the spool in the winding direction of the seat belt during operation, the rotating body having a pretensioner arranged on the same side as the lock mechanism with respect to the spool ,
The power transmission mechanism has a clutch arranged on a separate shaft from the rotation shaft of the spool,
The clutch provides a seat belt retractor that blocks transmission of torque from the spool to the motor and transmits torque from the motor to the spool.

According to the technique of the present disclosure, transmission of rotational force from the spool to the motor is cut off by the clutch, so that the occupant can smoothly pull out the seatbelt from the seatbelt retractor or cause the seatbelt retractor to wind the seatbelt smoothly. .

It is a figure which shows the structure of the seatbelt apparatus of one Embodiment. 1 is a perspective view of an embodiment seat belt retractor; FIG. It is a side view of the seat belt retractor of one embodiment. FIG. 3 is a diagram showing a cross-sectional view of the seat belt retractor of one embodiment along arrow AA (see FIG. 3); 1 is a side view of an embodiment seat belt retractor with a gear cover removed; FIG. It is an exploded perspective view of a power transmission mechanism. It is a figure which shows the structure of a power transmission mechanism typically. It is a side view of a clutch. It is an exploded perspective view of a clutch. FIG. 9 is a diagram showing a clutch off state (clutch pawl closed state) along arrows BB (see FIG. 8); FIG. 9 is a view showing the on state of the clutch (the clutch pawl opened state) in the arrow view BB (see FIG. 8);

Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a seat belt device according to one embodiment of the present disclosure. A seat belt device 101 shown in FIG. 1 is an example of a seat belt device mounted on a vehicle. The seatbelt device 101 includes, for example, a seatbelt 104, a retractor 103, a shoulder anchor 106, a tongue 107, and a buckle .

The seat belt 104 is an example of a seat belt that restrains the occupant 111 sitting on the seat 102 of the vehicle, and is a belt-like member that is retractably wound around the retractor 103 . A seat belt is also called webbing. A belt anchor 105 at the tip of the seat belt 104 is fixed to the seat 102 or the vehicle body near the seat 102 .

The retractor 103 is an example of a seat belt retractor capable of retracting or withdrawing the seat belt 104 . The retractor 103 restricts the seat belt 104 from being pulled out from the retractor 103 when an acceleration/deceleration or vehicle angle equal to or greater than a predetermined value is detected at the time of vehicle collision or the like. The retractor 103 is fixed to the seat 102 or the vehicle body near the seat 102 . Retractor 103 is an example of a seat belt retractor.

The retractor 103 has a function of winding the seat belt 104 around a spool by the power of the motor 103a. For example, before a vehicle collision, the retractor 103 operates a motor 103a based on a signal from a sensor such as a millimeter-wave radar to wind the seatbelt 104 on a spool and apply pretension to the seatbelt 104 so that the seatbelt 104 is retracted. Quickly restrain the occupant by Further, the retractor 103 operates the motor 103a to wind the seat belt 104 on the spool, for example, when the tongue 107 and the buckle 108 are disconnected. The retractor 103 operates, for example, a motor 103a to adjust the tension of the seat belt 104 according to the driving situation (state of the vehicle), thereby reducing the restraint of the occupant by the seat belt 104 and the comfort of wearing the seat belt 104. improve their individuality.

The state of the vehicle includes, for example, whether or not the seat belt 104 is pulled out, whether or not the occupant 111 is present, the traveling speed of the vehicle, the acceleration of the vehicle, the steering operation, the accelerator operation, the brake operation, the buckle 108 operation, the door operation, and the occupant's operation. This refers to a state that represents possible operation input of an in-vehicle selection switch, etc.

The shoulder anchor 106 is an example of a belt passer through which the seat belt 104 passes, and is a member that guides the seat belt 104 pulled out from the retractor 103 toward the shoulder of the occupant 111 . A shoulder anchor 106 is fixed to the seat 102 or to the vehicle body near the seat 102 .

The tongue 107 is an example of a belt passer through which the seat belt 104 passes, and is a component slidably attached to the seat belt 104 guided by the shoulder anchor 106 .

Buckle 108 is a component into which a flat locking portion of tongue 107 attached to seat belt 104 is inserted and removed, and tongue 107 is detachably connected. The buckle 108 is fixed, for example, to the seat 102 or the vehicle body near the seat 102 .

With the tongue 107 connected to the buckle 108 , the portion of the seat belt 104 between the shoulder anchor 106 and the tongue 107 is the shoulder belt portion 109 that restrains the chest and shoulders of the occupant 111 . With the tongue 107 connected to the buckle 108 , the portion of the seat belt 104 between the belt anchor 105 and the tongue 107 is the lap belt portion 110 that restrains the waist of the occupant 111 .

FIG. 2 is a perspective view of the seat belt retractor of one embodiment. FIG. 3 is a side view of the seat belt retractor of one embodiment. FIG. 4 is a diagram showing a cross-sectional view of the seat belt retractor of one embodiment along arrow AA (see FIG. 3). FIG. 5 is a side view of one embodiment of the seat belt retractor with the gear cover removed. FIG. 6 is an exploded perspective view of the power transmission mechanism of the seat belt retractor of one embodiment. FIG. 7 is a diagram schematically showing the configuration of the power transmission mechanism of the seat belt retractor of one embodiment.

The retractor 1 shown in FIGS. 2 to 7 is an example of a seat belt retractor, and more specifically an example of the retractor 103 shown in FIG. The configuration of the retractor 1 will be described below with reference to FIGS.

The retractor 1 includes a frame 2, a spool 4, a spring mechanism 11, a vehicle sensor 5, a lock mechanism 6, a torsion bar 7, a pretensioner 8 and a motor drive unit 13.

The frame 2 is a housing that rotatably accommodates the spool 4 and forms the skeleton of the retractor 1 . The frame 2 has, for example, a pair of facing side portions 2b and 2c and a back portion 2a connecting the side portions 2b and 2c. A spring mechanism 11 is arranged and fixed outside the side portion 2b (that is, on the side opposite to the spool 4 side with respect to the side portion 2b). The lock mechanism 6 and the power transmission mechanism 21 are arranged outside the side portion 2c (that is, on the opposite side of the side portion 2c to the spool 4 side). The pair of side portions 2b and 2c each have a circular (including substantially circular) opening.

The spool 4 is a winding member that is rotatably supported concentrically (including substantially concentrically) with the openings of the pair of side portions 2b and 2c of the frame 2 and that winds up the seat belt 104. As shown in FIG.

The spring mechanism 11 always biases the spool 4 so that the spool 4 rotates in the direction in which the seat belt 104 is wound around the spool 4 (the winding direction of the seat belt). A spiral spring 9 housed in the spring mechanism 11 urges the spool 4 to rotate in a direction in which the seat belt 104 is wound up.

The spiral spring 9 has one end connected to the rotating shaft of the spool 4 and the other end connected to the outer peripheral wall of the cover of the spring mechanism 11 so that the spool 4 rotates in the seat belt winding direction. It is an example of an elastic body that biases the spool 4 . One end of the spiral spring 9 is connected to a bush 10 fixed to one end of the rotating shaft of the spool 4 .

The vehicle sensor 5 is an example of a detection mechanism that detects a change in behavior of the vehicle (specifically, a rapid change in acceleration/deceleration or inclination of the vehicle caused by the change in behavior of the vehicle). The vehicle sensor 5 has a spherical body 5a that moves when the vehicle decelerates in an emergency, and a locking claw 5b that is actuated by the movement of the spherical body 5a.

The lock mechanism 6 performs a lock operation to lock the rotation of the spool 4 in the seat belt 104 withdrawal direction. The lock mechanism 6 has a lock gear 14 and a locking base 17 . The lock gear 14 is supported by the tip portion 7a of the torsion bar 7 projecting from the side surface portion 2c of the frame 2 to the left in FIG. The tip portion 7a may be a separate member such as a shaft that is axially connected to the torsion bar 7, or may be a part of the torsion bar 7 itself. The locking base 17 is rotatably supported by a first torque transmission portion 15, which will be described later, and holds the pawl 16 so as to swing. The locking base 17 is an example of a locking member, rotates together with the spool 4 during normal operation, and prevents the rotation of the spool 4 in the seat belt 104 withdrawal direction during operation. Ratchet teeth 14 a are formed on the outer circumference of the lock gear 14 . The lock gear 14 normally rotates together with the torsion bar 7 . On the other hand, in the above-described emergency, the ball 5a of the vehicle sensor 5 is actuated and the locking pawl 5b is engaged with the ratchet teeth 14a. As a result, rotation of the lock gear 14 in the direction of withdrawing the seat belt 104 is prevented, so rotation of the spool 4 in the direction of withdrawing the seat belt 104 is also prevented.

As shown in FIG. 4, the locking base 17 has a cylindrical shaft portion 17a and an annular disk-shaped flange portion 17c formed at one end of the shaft portion 17a.

The torsion bar 7 is formed with a first torque transmission portion 15 that is non-rotatably engaged with the locking base 17 and is non-rotatably engaged with the spool 4 at a predetermined distance from the first torque transmission portion 15 . A mating second torque transmission portion 18 is formed.

The pretensioner 8 is activated in the early stages of an emergency to generate reaction gas, and the belt winding torque generated by this reaction gas is transmitted to the spool 4 via the rotating body 81 . As a result, the seat belt 104 is wound on the spool 4 by a predetermined amount at the beginning of an emergency. The pretensioner 8 has a rotating body 81 connected to the end of the spool 4 via the torsion bar 7 and the locking base 17 and a power generator 82 that rotates the rotating body 81 .

The rotating body 81 rotates the spool 4 in the winding direction of the seat belt 104 when the pretensioner 8 is activated. The rotating body 81 is also called a paddle wheel. The rotor 81 is coaxially connected to the spool 4 . The projectile pushed by the gas generated by the gas generator (not shown) of the power generator 82 moves inside the pipe. Since the projectile moving in the pipe rotates the rotating body 81 in the seat belt 104 winding direction, the spool 4 also rotates in the seat belt 104 winding direction. As a result, the seat belt 104 is wound around the spool 4 .

The rotor 81 is arranged on the same side as the lock mechanism 6 with respect to the spool 4 . As a result, the arrangement position of the structure for locking the rotation of the spool 4 can be put together, and the size reduction of the retractor 1 can be facilitated.

As shown in FIGS. 4 to 7, the motor drive unit 13 includes a motor 12 that generates power to rotate the spool 4 and a power transmission mechanism 21 that reduces the power of the motor 12 and transmits it to the spool 4 .

The power transmission mechanism 21 has a gear case 29 , a motor gear 20 , a connect gear 22 , a clutch 25 , an idle gear 26 , a shaft gear 27 and a gear cover 28 .

Gear case 29 accommodates motor gear 20 , connect gear 22 , clutch 25 , idle gear 26 and shaft gear 27 . The motor 12 is fixed to the gear case 29, and the gear case 29 is fixed to the side surface portion 2c. The gear cover 28 is fixed to the gear case 29 while covering these gears housed in the gear case 29 .

The motor gear 20 is attached to the output shaft 12a of the motor 12 so as to rotate integrally therewith. The motor gear 20 has external teeth 20a and a shaft hole 20b into which the output shaft 12a is inserted.

The connect gear 22 always meshes with the outer teeth 20 a of the motor gear 20 and has a larger outer diameter than the motor gear 20 . The connect gear 22 rotates around a boss 29 a formed on the gear case 29 . The boss 29 a is positioned on a different axis from the output shaft 12 a of the motor 12 and is inserted into the shaft hole 22 c of the connect gear 22 . The connect gear 22 has a connect gear portion 22a having external teeth 22aa and a connect gear portion 22b having external teeth 22ba. The connect gear portion 22b has an outer diameter smaller than that of the connect gear portion 22a, and is coaxially fixed to the connect gear portion 22a. The external teeth 22aa are always in mesh with the external teeth 20a of the motor gear 20, and have more teeth than the external teeth 20a. The external teeth 22ba are always meshed with the external teeth 23a of the drive gear 23 of the clutch 25, and have more teeth than the external teeth 20a and less than the external teeth 23a.

The clutch 25 is arranged on a separate axis from the rotation axis of the spool 4 (in this embodiment, (the tip portion 7a thereof) of the torsion bar 7). By arranging the clutch 25 on a separate axis from the rotation axis of the spool 4, the retractor 1 can be moved in the axial direction of the rotation axis of the spool 4 compared to the configuration in which the clutch 25 is arranged coaxially with the rotation axis of the spool 4. An increase in width dimension can be minimized. In particular, since the lock mechanism 6 is arranged coaxially with the rotation axis of the spool 4, arranging the clutch 25 on a separate axis from the rotation axis of the spool 4 suppresses an increase in the width dimension due to the addition of the clutch 25. It is advantageous in terms of

Clutch 25 has drive gear 23 and clutch outer 24 .

The drive gear 23 is rotatably supported by a boss 29b on a shaft separate from the rotation shaft of the spool 4, and rotates as the output shaft 12a of the motor 12 rotates. The boss 29 b is inserted into the shaft hole 23 b of the drive gear 23 and the shaft hole 24 b of the clutch outer 24 . The drive gear 23 has an outer diameter larger than that of the connect gear 22 and has external teeth 23a.

The clutch outer 24 is rotatably supported coaxially with the drive gear 23, and is connected to the rotation shaft of the spool 4 via at least one gear (in this embodiment, two gears, an idle gear 26 and a shaft gear 27). . The clutch outer 24 has external teeth 24a having fewer teeth than the external teeth 23a, and a shaft hole 24b into which a boss 29b is inserted. The clutch outer 24 rotates around a boss 29 b of the gear case 29 . The external teeth 24a mesh with the external teeth 26a of the idle gear 26 all the time.

The idle gear 26 has external teeth 26a having more teeth than the external teeth 24a of the clutch outer 24, and a shaft hole 26b into which a boss 29c is inserted. The idle gear 26 rotates around a boss 29 c formed on the gear case 29 . The external teeth 26 a are in constant mesh with both the external teeth 24 a of the clutch outer 24 and the external teeth 27 a of the shaft gear 27 .

The shaft gear 27 has external teeth 27a having a larger number of teeth than the external teeth 24a of the clutch outer 24, and a shaft hole 27b into which the tip portion 7a coaxial with the rotating shaft of the spool 4 is inserted. The shaft gear 27 is coaxially connected to the rotating shaft of the spool 4 and is fixed to the distal end portion 7a inserted into the shaft hole 27b so as not to rotate relative to it.

8 is a side view of the clutch 25. FIG. 9 is an exploded perspective view of the clutch 25. FIG. FIG. 10 is a diagram showing an off state (clutch pawl closed state) of the clutch 25 along the arrow BB (see FIG. 8). FIG. 11 is a view showing the ON operation of the clutch (clutch pawl open state) in the direction of arrows BB (see FIG. 8). Next, the configuration of the clutch 25 will be described in more detail with reference to FIGS. 8-11.

The clutch 25 includes a drive gear 23, a clutch outer 24 that is rotatably supported coaxially with the drive gear 23, a pair of clutch pawls 41 provided on the drive gear 23, and a pair of clutch pawls 41 that bias the pair of clutch pawls 41. and a clutch spring 42 .

An end face 23i of the drive gear 23 is formed with a pair of bosses 23e and 23h, a pair of mounting portions 23c and 23f, and a pair of stoppers 23d and 23g. Inside the outer peripheral wall 24c of the clutch outer 24, ratchet internal teeth 24d are formed.

The clutch pawl 41a is supported by the boss 23e so as to swing around the boss 23e along the end surface 23i. The clutch pawl 41b is supported by the boss 23h so as to swing around the boss 23h along the end surface 23i.

The clutch pawl 41a has a pushed portion 41ab formed on one side with respect to the boss 23e and a claw portion 41aa formed on the other side with respect to the boss 23e. The clutch pawl 41b has a pushed portion 41bb formed on one side with respect to the boss 23h and a claw portion 41ba formed on the other side with respect to the boss 23h.

The clutch spring 42a urges the pressed portion 41ab toward the ratchet inner tooth 24d and urges the pawl portion 41aa away from the ratchet inner tooth 24d. A biasing member disposed therebetween. The clutch spring 42a has one spring end attached to the attachment portion 23c and the other spring end that pushes the pressed portion 41ab in a direction approaching the ratchet internal teeth 24d. The stopper 23d limits the movement of the pressed portion 41ab in the direction toward the ratchet inner tooth 24d so that the pressed portion 41ab does not come into contact with the ratchet inner tooth 24d.

Similarly, the clutch spring 42b urges the pressed portion 41bb toward the ratchet inner tooth 24d and urges the pawl portion 41ba away from the ratchet inner tooth 24d. 41bb. The clutch spring 42b has one spring end attached to the attachment portion 23f and the other spring end that pushes the pressed portion 41bb in a direction approaching the ratchet internal teeth 24d. A stopper 23g restricts the movement of the pressed portion 41bb in the direction toward the ratchet inner tooth 24d so that the pressed portion 41bb does not come into contact with the ratchet inner tooth 24d.

Therefore, as shown in FIG. 10, when the drive gear 23 stops rotating, the clutch pawl 41a is held at a position where it does not engage with the ratchet internal teeth 24d of the clutch outer 24 due to the biasing force of the clutch spring 42a. be. That is, the pawl portion 41aa does not engage with the ratchet internal teeth 24d.

Similarly, as shown in FIG. 10, when the drive gear 23 stops rotating, the clutch pawl 41b is held at a position where it does not engage with the ratchet internal teeth 24d of the clutch outer 24 according to the biasing force of the clutch spring 42b. be done. That is, the pawl portion 41ba does not engage with the ratchet internal teeth 24d.

On the other hand, when the output shaft 12a of the motor 12 is rotating, the rotation of the motor gear 20 and the connect gear 22 causes the drive gear 23 to rotate about the shaft hole 24b. When the drive gear 23 rotates, centrifugal force acts on the clutch pawls 41a and 41b.

When the drive gear 23 rotates in the direction corresponding to the winding direction of the seat belt 104 due to the rotation of the output shaft 12a, the clutch pawl 41a moves due to its centrifugal force while resisting the biasing force of the clutch spring 42a. The clutch pawl 41a moved by the centrifugal force engages with the ratchet internal teeth 24d of the clutch outer 24 (see FIG. 11). That is, the pawl portion 41aa engages with the ratchet internal teeth 24d. Conversely, when the drive gear 23 rotates in the direction corresponding to the withdrawal direction of the seat belt 104 due to the rotation of the output shaft 12a, the clutch pawl 41a moves toward the ratchet internal teeth 24d due to the stopper 23d even if the centrifugal force acts thereon. movement is restricted. Therefore, the engagement between the clutch pawl 41a and the ratchet internal tooth 24d is prevented (see FIG. 10). That is, the pawl portion 41aa does not engage with the ratchet internal teeth 24d.

Similarly, the clutch pawl 41b engages with the ratchet internal teeth 24d when the drive gear 23 rotates in the direction corresponding to the winding direction of the seat belt 104 due to the rotation of the output shaft 12a (see FIG. 11). That is, the pawl portion 41ba engages with the ratchet internal teeth 24d. Conversely, the clutch pawl 41b does not engage with the ratchet internal teeth 24d when the drive gear 23 rotates in the direction corresponding to the withdrawal direction of the seat belt 104 due to the rotation of the output shaft 12a (see FIG. 10). That is, the pawl portion 41ba does not engage with the ratchet internal teeth 24d.

Therefore, when the drive gear 23 rotates in the direction corresponding to the winding direction of the seat belt 104 due to the rotation of the output shaft 12a, the pawls 41aa and 41ba of the clutch pawls 41a and 41b are engaged with the ratchet internal teeth 24d. state is maintained. In this engaged state, the rotational power of the output shaft 12 a is transmitted through the motor gear 20 , the connect gear 22 , the drive gear 23 , the pair of clutch pawls 41 and the clutch outer 24 in order. The clutch outer 24 is connected to the rotating shaft of the spool 4 via an idle gear 26 and a shaft gear 27 . Therefore, in such an engaged state, the rotational force of the output shaft 12 a is transmitted to the rotational shaft of the spool 4 , so the seat belt 104 is wound around the spool 4 .

On the other hand, when the drive gear 23 is rotated in the direction corresponding to the withdrawal direction of the seat belt 104 due to the rotation of the output shaft 12a, the pawls 41aa and 41ba of the clutch pawls 41a and 41b do not engage the ratchet internal teeth 24d. state is maintained. Further, when the rotation of the output shaft 12a is stopped, the rotation of the drive gear 23 is also stopped, so that the claw portions 41aa and 41ba of the clutch pawls 41a and 41b are maintained in a state in which they do not engage with the ratchet internal teeth 24d. be done. In these disengaged states, the rotational force of the rotating shaft of the spool 4 is transmitted through the shaft gear 27 , the idle gear 26 and the clutch outer 24 in order, but is not transmitted to the drive gear 23 . Therefore, in such a disengaged state, the rotational force of the rotating shaft of the spool 4 is not transmitted to the output shaft 12a. That is, transmission of torque from the rotation shaft of the spool 4 to the output shaft 12a is cut off.

Thus, the clutch 25 is a one-way clutch that blocks transmission of torque from the spool 4 to the motor 12 and transmits torque from the motor 12 to the spool 4 . Therefore, transmission of rotational force from the spool 4 to the motor 12 is interrupted by the clutch 25, so that the occupant 111 can smoothly withdraw the seat belt 104 from the retractor 1 or cause the retractor 1 to wind the seat belt 104 smoothly.

Further, as shown in FIG. 7, the power transmission mechanism 21 includes a first reduction mechanism 51 that reduces the rotation of the output shaft 12a of the motor 12 and transmits it to the drive gear 23, and a first reduction mechanism 51 that reduces the rotation of the clutch outer 24. and a second speed reduction mechanism 52 for transmission to the rotating shaft of the spool 4 . By disposing the clutch 25 between the first speed reduction mechanism 51 and the second speed reduction mechanism 52 in this way, at least one of the first speed reduction mechanism 51 and the second speed reduction mechanism 52 is eliminated. In comparison, the power of the motor 12 can be efficiently transmitted to the clutch 25 . Therefore, the drive gear 23 can be rotated at an appropriate rotational speed without excessively or excessively reducing the rotational speed of the output shaft 12a of the motor 12, thereby generating an appropriate centrifugal force in the pair of clutch pawls 41. be able to.

For example, it is preferable that the reduction ratio of the first speed reduction mechanism 51 is larger than that of the second speed reduction mechanism 52 in that the power of the motor 12 can be efficiently transmitted to the clutch 25 . For example, setting the reduction ratio of the first reduction mechanism 51 to 10 and setting the reduction ratio of the second reduction mechanism 52 to 3 is preferable in that the power of the motor 12 can be efficiently transmitted to the clutch 25 .

In this embodiment, the first speed reduction mechanism 51 has the motor gear 20 and the connect gear 22 , and the speed reduction ratio of the first speed reduction mechanism 51 represents the speed reduction ratio between the motor gear 20 and the drive gear 23 . In this embodiment, the second reduction mechanism 52 has an idle gear 26 and a shaft gear 27, and the reduction ratio of the second reduction mechanism 52 represents the reduction ratio between the clutch outer 24 and the shaft gear 27. .

Next, other movements of the retractor 1 of this example will be described.

When the seat belt is not worn, the seat belt 104 is completely retracted by the biasing force of the spring mechanism 11 . When the seat belt is not worn, the motor 12 is stopped and the pair of clutch pawls 41 are not engaged with the ratchet internal teeth 24d of the clutch outer 24. As shown in FIG.

When the occupant 111 pulls out the seat belt 104 at a normal speed for wearing, the spool 4 rotates in the direction of pulling out the seat belt 104, and the seat belt 104 is pulled out. After the tongue 107 slidably provided on the seat belt 104 is inserted into the buckle 108 and locked, the excessively pulled out seat belt 104 is pulled out to the spool 4 by the biasing force of the spring mechanism 11 and the power of the motor 12. be wound up. As a result, the seat belt 104 fits to the occupant 111 to such an extent that it does not give a feeling of oppression. Further, by inserting the tongue 107 into the buckle 108 and locking it, a buckle switch (not shown) is turned on, and the motor 12 is ready to be driven.

At the initial stage of the above-described emergency, the seat belt retracting torque generated by the pretensioner 8 is transmitted to the spool 4 via the rotating body 81, and the spool 4 retracts the seat belt 104 by a predetermined amount to restrain the occupant 111. Restrain quickly. On the other hand, when a large vehicle deceleration occurs in an emergency, the vehicle sensor 5 is activated and the lock mechanism 6 is activated as described above. That is, the operation of the vehicle sensor 5 prevents the rotation of the lock gear 14 in the seat belt withdrawing direction, and the pawl 16 of the lock mechanism 6 rotates to engage the internal teeth 2ca of the side wall (side surface 2c) of the frame 2. engage.

When the pawl 16 engages with the inner tooth 2ca, the locking base 17 is prevented from rotating in the seat belt withdrawing direction. However, the inertia of the occupant 111 exerts a pull-out force on the seat belt 104, causing the spool 4 to rotate in the belt pull-out direction. Rotate relative to

The motor 12 is connected via a power transmission mechanism 21 arranged on the same side of the spool 4 as the locking mechanism 6 to a locking base 17 of the torsion bar 7 that is prevented from rotating in the seat belt withdrawing direction. Therefore, even if only the spool 4 rotates relative to the locking base 17 in the seat belt withdrawing direction, the rotation of the spool 4 is blocked by the locking base 17 and transmitted to the motor 12 via the clutch 25 of the power transmission mechanism 21. not. As a result, the spool 4 rotates without resistance from the motor 12 . Therefore, impact energy is easily transmitted to the torsion bar 7 . Thereafter, the spool 4 rotates in the seat belt withdrawing direction while twisting the torsion bar 7 , and the torsion torque of the torsion bar 7 absorbs and mitigates the impact energy of the occupant 111 more satisfactorily. Applied loads are limited.

In addition, in the retractor 1 of this example, even when the seat belt 104 is suddenly pulled out, the inertia member 31 (shown in FIGS. 4 and 6) operates to prevent the locking base 17 of the lock mechanism 6 from moving against the lock gear 14 . It has a configuration to relatively rotate in the seat belt withdrawing direction. Since the operation of this inertia member 31 is a well-known technique, its detailed description is omitted. With this configuration, the pawl 16 of the locking mechanism 6 engages with the inner tooth 2ca to prevent rotation of the locking base 17 in the same manner as described above. is blocked, and withdrawal of the seat belt 104 is blocked.

On the other hand, the motor 12 may be driven in a rotational direction corresponding to the belt winding direction of the spool 4 in order to control the belt tension of the seat belt 104 in the normal seat belt wearing state. The rotational force is transmitted to the spool 4 through the motor gear 20, the connect gear 22, the drive gear 23, the clutch outer 24, the idle gear 26, the shaft gear 27, the locking base 17, and the torsion bar 7, and the spool 4 winds the belt. rotate in the direction As a result, the seat belt 104 is wound up and the belt tension is increased.

Although the seat belt retractor has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. Various modifications and improvements such as combination or replacement with part or all of other embodiments are possible within the scope of the present invention.

For example, the number of clutch pawls is not limited to two, and may be one or three or more. Further, the number of gears included in each of the first speed reduction mechanism 51 and the second speed reduction mechanism 52 is not limited to two, and may be one or three or more.

1 Retractor 2 Frame 4 Spool 5 Vehicle Sensor 6 Lock Mechanism 7 Torsion Bar 8 Pretensioner 9 Spiral Spring 11 Spring Mechanism 12 Motor 13 Motor Drive Unit 14 Lock Gear 16 Pawl 17 Locking Base 20 Motor Gear 21 Power Transmission Mechanism 22 Connect Gear 23 Drive Gear 24 clutch outer 25 clutch 26 idle gear 27 shaft gear 28 gear cover 29 gear case 31 inertia member 51 first reduction mechanism 52 second reduction mechanism

Claims (9)

a spool for winding the seat belt;
a lock mechanism having a locking member that normally rotates together with the spool and prevents the spool from rotating in the seat belt withdrawal direction during operation;
a motor that generates power to rotate the spool;
a power transmission mechanism disposed on the same side of the spool as the lock mechanism and transmitting power of the motor to the spool ;
A rotating body that rotates the spool in the winding direction of the seat belt during operation, the rotating body having a pretensioner arranged on the same side as the lock mechanism with respect to the spool ,
The power transmission mechanism has a clutch arranged on a separate shaft from the rotation shaft of the spool,
The seat belt retractor, wherein the clutch interrupts transmission of rotational force from the spool to the motor and transmits rotational force from the motor to the spool. The clutch cuts off transmission of rotational force from the rotating shaft to the output shaft when the output shaft of the motor stops rotating, and transmits torque from the output shaft to the output shaft when the output shaft is rotating. 2. The seat belt retractor of claim 1, wherein the seat belt retractor transmits rotational force to a rotating shaft. The clutch is
a drive gear that is rotatably supported by a shaft different from the rotation shaft and that rotates according to the rotation of the output shaft;
a clutch outer rotatably supported coaxially with the drive gear and coupled to the rotating shaft via at least one gear;
a clutch pawl provided on the drive gear;
3. The clutch pawl according to claim 2, wherein the clutch pawl is moved by a centrifugal force generated by rotation of the drive gear to engage with the clutch outer, and does not engage with the clutch outer when the drive gear stops rotating. seat belt retractor. The clutch pawl is moved by the centrifugal force while resisting the biasing force of the biasing member and engages with the clutch outer. 4. The seat belt retractor of claim 3, held in a disengaged position. 5. The seatbelt retractor according to claim 3, wherein said clutch pawl is swingably supported by an end face of said drive gear and engages with internal teeth of said clutch outer by said centrifugal force. The power transmission mechanism is
a first speed reduction mechanism that reduces the speed of rotation of the output shaft and transmits the speed to the drive gear;
The seatbelt retractor according to any one of claims 3 to 5, further comprising a second speed reduction mechanism that reduces rotation of said clutch outer and transmits the reduced speed to said rotating shaft. 7. The seat belt retractor according to claim 6, wherein the reduction ratio of said first reduction mechanism is greater than the reduction ratio of said second reduction mechanism. 8. The seat belt retractor according to claim 6 or 7, wherein said second reduction mechanism comprises said at least one gear. The seat belt retractor according to any one of claims 3 to 8, wherein the clutch has a biasing member that biases the clutch pawl.

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