Seat belt retractor and seat belt device

To provide a seat belt retractor and a seat belt device capable of shortening time taken to restrict rotation of a spool. A seat belt retractor according to the present invention includes a spool 2, a base frame 3, a spring unit 4, a vehicle sensor 5, a locking mechanism 6, and a pretensioner 7. The locking mechanism 6 includes a lock gear 61 and a retainer 62. The lock gear 61 includes an outer circumferential wall 61a that is disposed at an end portion of the spool 2 and engageable with the vehicle sensor 5. The retainer 62 includes an inner circumferential wall 62a disposed on the inner side of the outer circumferential wall 61a and a side wall 62e that defines a space accommodating the lock gear 61. The lock gear 61 becomes engaged with the inner circumferential wall 62a or the side wall 62e of the retainer 62 when the lock gear 61 becomes eccentric relative to the retainer 62.

FIELD OF THE INVENTION

The present invention relates to seat belt retractors and seat belt devices, and more specifically, to a seat belt retractor including a lock gear at an end portion of a spool and a seat belt device including the seat belt retractor.

BACKGROUND OF THE INVENTION

A vehicle such as an automobile generally includes a seat belt device that restrains an occupant in a seat including a seat portion, on which an occupant is seated, and a backrest portion located on the back of the occupant. Such a seat belt device includes a webbing that restrains the occupant, a seat belt retractor that retracts the webbing, a guide anchor that is disposed on a vehicle body and that guides the webbing, a belt anchor that fixes the webbing to the vehicle body, a buckle disposed on a side surface of the seat, and a tongue disposed on the webbing. Fitting the tongue into the buckle causes the webbing to restrain the occupant in the seat.

Such a seat belt retractor often includes a spool on which a webbing is wound, a base frame that accommodates the spool while allowing the spool to rotate, a spring unit that applies a retracting force to the spool, a vehicle sensor (also referred to as an acceleration sensor or a shock sensor) that detects sudden deceleration of the vehicle, a locking mechanism that is activated by the vehicle sensor and that causes the spool to be engaged with the base frame, and a pretensioner that removes the slack of the webbing in case of emergency such as a collision of the vehicle (see, for example, Japanese Unexamined Patent Application Publication No. 2013-86759 and Japanese Unexamined Patent Application Publication No. 2014-80121).

SUMMARY OF INVENTION

Generally, in the above-described seat belt retractor, both end portions of the spool are often inserted into an opening formed in a base plate, one end portion is often supported by the spring unit fixed to the base plate, and the other end portion is often supported by a pretensioner cover that accommodates part of the pretensioner or a retainer that accommodates the locking mechanism. A lock gear included in the locking mechanism is fitted in an end portion of the spool so as to be coaxial with the spool.

The vehicle sensor generally includes a spherical mass body and a sensor lever that swings in accordance with the movement of the mass body. When the vehicle decelerates to or below a predetermined rate or leans a predetermined degree or greater, the balance of the mass body is lost and the sensor lever is pushed upward. Then, the end of the sensor lever becomes engaged with the lock gear, so that the rotation of the lock gear is restricted. Finally, the rotation of the spool is restricted.

As described above, during the time from when the vehicle sensor detects sudden deceleration or other events of the vehicle until when the rotation of the spool is restricted and the pull-out of the webbing is restricted, it takes a predetermined time length from when the sensor lever swings until when its end becomes engaged on the lock gear. In these years, an enhancement of the performance is highly required also in the field of the seat belt device and an existing seat belt retractor is required to further shorten the time taken to restrict the rotation of the spool.

The present invention is made in view of the above-described problems and aims to provide a seat belt retractor and a seat belt device that enable a shortening of time taken to restrict rotation of a spool.

The present invention provides a seat belt retractor that includes a spool that retracts a webbing that restrains an occupant; a base frame that accommodates the spool while allowing the spool to rotate; a vehicle sensor that detects sudden deceleration of a vehicle; and a locking mechanism that is activated by the vehicle sensor and that causes the spool to be engaged with the base frame. The locking mechanism includes a lock gear and a retainer, the lock gear includes an outer circumferential wall that is disposed at an end portion of the spool and engageable with the vehicle sensor, and the retainer includes an inner circumferential wall disposed on an inner side of the outer circumferential wall and a side wall that defines a space accommodating the lock gear. When the lock gear becomes eccentric relative to the retainer, the lock gear becomes engaged with the inner circumferential wall or the side wall of the retainer.

The present invention also provides a seat belt device that includes a webbing that restrains an occupant; a seat belt retractor that retracts the webbing; a guide anchor that is disposed on a vehicle body and that guides the webbing; a belt anchor that fixes the webbing to the vehicle body; a buckle disposed on a side surface of a seat on which the occupant is seated; and a tongue that is disposed on the webbing. The seat belt retractor includes a spool that retracts the webbing; a base frame that accommodates the spool while allowing the spool to rotate; a vehicle sensor that detects sudden deceleration of a vehicle; and a locking mechanism that is activated by the vehicle sensor and that causes the spool to be engaged with the base frame. The locking mechanism includes a lock gear and a retainer, the lock gear includes an outer circumferential wall that is disposed at an end portion of the spool and engageable with the vehicle sensor, and the retainer includes an inner circumferential wall disposed on an inner side of the outer circumferential wall and a side wall that defines a space accommodating the lock gear. When the lock gear becomes eccentric relative to the retainer, the lock gear becomes engaged with the inner circumferential wall or the side wall of the retainer.

In the seat belt retractor and the seat belt device described above, engagement inner teeth may be formed on an inner surface of the outer circumferential wall and engagement outer teeth engageable with the engagement inner teeth may be formed at at least a portion of an outer surface of the inner circumferential wall. The engagement inner teeth may be formed over an entire circumference of the inner surface of the outer circumferential wall.

The engagement outer teeth may be formed at a portion of the inner circumferential wall that touches the outer circumferential wall when the lock gear becomes eccentric in a direction in which the webbing is pulled out. The seat belt retractor may include a pretensioner that removes slack of the webbing, and the engagement outer teeth may be formed at a portion of the inner circumferential wall that touches the outer circumferential wall when the lock gear becomes eccentric in a direction in which a reaction force caused in the spool at activation of the pretensioner is exerted.

In the seat belt retractor and the seat belt device described above, engagement teeth engageable with the vehicle sensor may be formed on an outer surface of the outer circumferential wall and an engagement portion engageable with the engagement teeth may be formed at at least a portion of an inner surface of the side wall. The engagement portion may be formed over a substantially entire area of the side wall that covers the outer circumferential wall.

The engagement portion may be formed at a portion of the side wall that touches the outer circumferential wall when the lock gear becomes eccentric in a direction in which the webbing is pulled out. The seat belt retractor may include a pretensioner that removes slack of the webbing, and the engagement portion may be formed at a portion of the side wall that touches the outer circumferential wall when the lock gear becomes eccentric in a direction in which a reaction force caused in the spool at activation of the pretensioner is exerted.

In the seat belt retractor and the seat belt device according to the present invention described above, the engagement inner teeth are formed on the inner surface of the outer circumferential wall of the lock gear and the engagement outer teeth are formed on the outer surface of the inner circumferential wall of the retainer. Thus, the seat belt retractor and the seat belt device can restrict the rotation of the lock gear as a result of engaging the engagement inner teeth and the engagement outer teeth with one another when the spool (lock gear) moves and becomes eccentric relative to the retainer, and therefore restrict the rotation of the spool. The seat belt retractor and the seat belt device thus can restrict the rotation of the lock gear without the vehicle sensor and shorten the time taken to restrict the rotation of the spool, whereby the performance of the seat belt retractor and the seat belt device can be enhanced.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now toFIGS. 1 to 7, embodiments of the present invention are described below. Here,FIG. 1is a partially detailed drawing of a seat belt retractor according to a first embodiment of the present invention.FIGS. 2(A) and 2(B)illustrate an entire configuration of the seat belt retractor illustrated inFIG. 1, whereFIG. 2(A)is a partially exploded view of the seat belt retractor andFIG. 2(B)is a perspective view of the inside of the retainer. Each of the drawings omits the illustration of the webbing for convenience purposes. InFIG. 1, only the main components in the embodiment are illustrated.

As illustrated inFIG. 1toFIG. 2(B), a seat belt retractor1according to a first embodiment of the present invention includes a spool2that retracts a webbing that restrains an occupant, a base frame3that accommodates the spool2while allowing the spool2to rotate, a spring unit4that applies a retracting force to the spool2, a vehicle sensor5that detects sudden deceleration of the vehicle, a locking mechanism6that is activated by the vehicle sensor5and that causes the spool2to be engaged with the base frame3, and a pretensioner7that removes the slack of the webbing. The locking mechanism6includes a lock gear61and a retainer62. The lock gear61includes an outer circumferential wall61athat is disposed at an end portion of the spool2and engageable with the vehicle sensor5. The retainer62includes an inner circumferential wall62adisposed on the inner side of the outer circumferential wall61aand a side wall62ethat defines a space accommodating the lock gear61. The lock gear61becomes engaged with the inner circumferential wall62aof the retainer62when the lock gear61becomes eccentric relative to the retainer62.

The spool2is a winding drum that retracts the webbing. For example, the spool2has its one end rotatably supported by the spring unit4and the other end rotatably supported by the retainer62. The spring unit4and the retainer62are directly or indirectly fixed to the base frame3. The spool2is inserted into openings31formed in the base frame3and supported by the spring unit4and the retainer62.

In the seat belt retractor1illustrated inFIG. 2(A), the locking mechanism6, the spool2, the pretensioner7, and the spring unit4are arranged in this order but the arrangement order is not limited to this order. For example, in the seat belt retractor1, the spring unit4, the locking mechanism6, the spool2, and the pretensioner7may be arranged in this order. In this case, the spool2is rotatably supported by the spring unit4and a pretensioner cover71.

The base frame3is a frame structure having, for example, a substantially angular U-shaped cross section. A pair of wall members constituting side surfaces is formed on both ends of a wall member constituting a back surface. The openings31through which the spool2is inserted are formed in the pair of wall members constituting the side surfaces. Alternatively, a tie plate32constituting a front surface may be connected to the ends of the pair of wall members constituting the side surfaces. As illustrated inFIG. 2(A), engagement teeth31aare formed at the inner edge of each opening31.

The pretensioner7is fixed to one of the side surfaces of the base frame3and the spring unit4is fixed to the outer side of the pretensioner7. The locking mechanism6is disposed on the other side surface of the base frame3and the retainer62that accommodates the components of the locking mechanism6is fixed to the other side surface of the base frame3. The pretensioner7includes, for example, a pretensioner cover71that surrounds the outer periphery of a ring gear (not illustrated) connected to the spool2, a mass body (not illustrated) that applies a rotational force to the ring gear that is injected into the inside of the pretensioner cover71, a pipe72that accommodates the mass body, and a gas generator73that provides power to the mass body.

The vehicle sensor5includes, for example, a spherical mass body51, a sensor lever52that swings in accordance with a movement of the mass body51, and a sensor cover53that allows the mass body51and the sensor lever52to be accommodated in the space defined between the sensor cover53and the retainer62. When the vehicle body decelerates to or below a predetermined rate or leans a predetermined degree or greater, the balance of the mass body51is lost and the vehicle sensor5allows the sensor lever52to be pushed upward. Thus, the end of the sensor lever52becomes engaged with the lock gear61, so that the rotation of the lock gear61is restricted.

The locking mechanism6includes, for example, a pawl63swingably disposed at the end portion of the spool2(specifically, a locking base connected to the end portion of the spool2), a spring64disposed between the end portion of the spool2(locking base) and the lock gear61and urging the lock gear61in the circumferential direction, the lock gear61disposed so as to be rotatable relative to the end portion of the spool2(locking base), a flywheel65swingably disposed on the lock gear61, a spring66urging the end of the flywheel65inward, and the retainer62accommodating these components including the lock gear61.

The lock gear61includes a disk portion61cdisposed so as to face the end portion of the spool2(locking base) and an outer circumferential wall61adisposed so as to extend straight toward the outer side along the outer edge of the disk portion61c. On the outer surface of the outer circumferential wall61a, engagement teeth61dengageable with the sensor lever52of the vehicle sensor5are formed.

The retainer62includes a substantially cylindrical protruding portion62c, which covers the outer circumference of the outer circumferential wall61aof the lock gear61, and an inner circumferential wall62a, formed on the inner side of the protruding portion62cand disposed on the inner side of the outer circumferential wall61aof the lock gear61. Thus, when the locking mechanism6is assembled, the outer circumferential wall61aof the lock gear61is inserted into a space between the inner circumferential wall62aand the protruding portion62cand the flywheel65is disposed on the inner side of the inner circumferential wall62a. On the inner surface of the inner circumferential wall62a, hooks62dengageable with the end of the flywheel65are formed. The protruding portion62chas a side wall62edisposed along at least part of the outer circumference of the outer circumferential wall61aof the lock gear61.

The locking mechanism6having such a configuration allows the lock gear61to rotate together with the rotation of the spool2in a normal state (when the pull-out force on the webbing is smaller than or equal to a predetermined threshold). Because the spool2and the lock gear61do not rotate relative to each other in the normal state, the pawl63thus remains in the state in which the position of the pawl63does not interfere with the engagement teeth31aformed around the opening31of the base frame3.

In the case where the webbing is pulled out at a rate higher than the normal pull-out rate, that is, when the pull-out force on the webbing exceeds a predetermined threshold, the flywheel65swings and becomes engaged with one of the hooks62dof the retainer62, so that the rotation of the lock gear61is restricted. Also in the case where the vehicle sensor5is activated, the rotation of the lock gear61is restricted as a result of the end of the sensor lever52becoming engaged with one of the engagement teeth61dformed on the outer surface of the outer circumferential wall61aof the lock gear61.

When the rotation of the lock gear61is restricted in this manner, a relative rotation occurs between the spool2and the lock gear61, the pawl63swings in accordance with this relative rotation, and the end of the pawl63approaches and becomes engaged with one of the engagement teeth31aformed around the opening31of the base frame3. Consequently, the rotation of the spool2is restricted and pull-out of the webbing is restricted.

As described above, the spool2is inserted into the openings31of the base frame3and a gap is left between the spool2and each opening31of the base frame3. In contrast to the base frame3having a rigid structure, the spool2has a relatively soft structure. Thus, when the webbing is pulled hard in the pull-out direction, the spool2may move and become eccentric relative to the base frame3. Also in the case where the pretensioner7is activated, a reaction force may occur in the spool2, so that the spool2may move and become eccentric relative to the base frame3.

On the other hand, as described above, to restrict the rotation of the lock gear61for restricting the rotation of the spool2, activation of the flywheel65or the vehicle sensor5is required. This activation involves a predetermined time length, although a short period, until the rotation of the lock gear61(spool2) is restricted.

Thus, the present invention focuses an attention on the phenomenon in which the above-described spool2moves and becomes eccentric relative to the base frame3and aims to restrict the rotation of the spool2. Specifically, as illustrated inFIGS. 1 to 2(B), engagement inner teeth61bare formed on the inner surface of the outer circumferential wall61aof the lock gear61and engagement outer teeth62bengageable with the engagement inner teeth61bare formed on at least part of the outer surface of the inner circumferential wall62aof the retainer62.

The engagement outer teeth62bare formed on the retainer62(inner circumferential wall62a), which is a stationary component, whereas the engagement inner teeth61bare formed on the lock gear61, which is a rotational component. Thus, preferably, the engagement inner teeth61bare formed over the entire inner surface of the outer circumferential wall61a. The engagement outer teeth62bare formed at a necessary portion, for example, a portion of the inner circumferential wall62athat touches the outer circumferential wall61awhen the lock gear61becomes eccentric in the webbing pull-out direction F (in the arrow direction inFIG. 1).

Here,FIGS. 3(A)and (B) illustrate an operation of the seat belt retractor illustrated inFIG. 1, whereFIG. 3(A)illustrates a state before the lock gear and the retainer are engaged together andFIG. 3(B)illustrates a state after the lock gear and the retainer are engaged together.FIGS. 3(A) and 3(B)are vertical cross sections of the side wall62econstituting the protruding portion62cillustrated inFIG. 2(A)when viewed from the outside of the retainer62. Throughout the drawings, the outer circumferential wall61aand the inner circumferential wall62aare filled with gray for convenience of illustration.

As illustrated inFIG. 3(A), in the normal state, specifically, for example, when the webbing is free from hard pulling force in the webbing pull-out direction F, the spool2is not moved (not eccentrically located) relative to the base frame3, a predetermined gap is left (in a non-engagement state) between the engagement inner teeth61bof the lock gear61and the engagement outer teeth62bof the retainer62.

On the other hand, as illustrated inFIG. 3(B), when, for example, the spool2is pulled hard in the webbing pull-out direction F, the spool2moves and becomes eccentric upward inFIG. 3(B)relative to the base frame3. Thus, the lock gear61also moves upward inFIG. 3(B)and becomes eccentric in association with the movement of the spool2, whereby the engagement inner teeth61bof the lock gear61and the engagement outer teeth62bof the retainer62touch one another (become engaged together).

This engagement of the engagement inner teeth61bwith the engagement outer teeth62benables restriction of the rotation of the lock gear61without activating the flywheel65or the vehicle sensor5. Thus, the time taken to restrict the rotation of the spool2can be shortened and the performance of the seat belt retractor1can be enhanced. In the case where the engagement inner teeth61btouch a portion of the inner circumferential wall62afree from the engagement outer teeth62b, the rotation of the lock gear61is not restricted since it has no teeth that become engaged with the engagement inner teeth61b.

Referring now toFIGS. 4(A) to 4(C), modified examples of the seat belt retractor1according to the first embodiment are described. Here,FIGS. 4(A) to 4(C)illustrate modified examples of the seat belt retractor illustrated inFIG. 1, whereFIG. 4(A)illustrates a first modified example,FIG. 4(B)illustrates a second modified example, andFIG. 4(C)illustrates a third modified example. Each drawing illustrates only the inner circumferential wall62aviewed in the same direction as in the case ofFIG. 3(A)and omits illustrations of other components as they are the same as those in the above-described embodiment.

The first modified example illustrated inFIG. 4(A)includes engagement outer teeth62bformed at a portion of the inner circumferential wall62athat touches the outer circumferential wall61awhen the lock gear61becomes eccentric in a direction F′ in which the reaction force caused in the spool2at activation of the pretensioner7is exerted. The second modified example illustrated inFIG. 4(B)includes engagement outer teeth62bformed at two portions of the inner circumferential wall62athat touch the outer circumferential wall61awhen the lock gear61becomes eccentric in the webbing pull-out direction F and in the direction F′ in which the reaction force caused in the spool2at activation of the pretensioner7is exerted. The third modified example illustrated inFIG. 4(C)includes engagement outer teeth62bformed at four portions, at the top, bottom, right, and left portions.

In this manner, the engagement outer teeth62bcan be formed as needed on any direction to which the spool2possibly moves and becomes eccentric relative to the base frame3. For example, although not illustrated, the engagement outer teeth62bmay be formed over the entire outer surface of the inner circumferential wall62a.

Referring now toFIGS. 5(A) and 5(B), a seat belt retractor according to a second embodiment of the present invention is described below. Here,FIGS. 5(A) and 5(B)illustrate a seat belt retractor according to a second embodiment of the present invention, whereFIG. 5(A)illustrates a state before the lock gear and the retainer are engaged together andFIG. 5(B)illustrates a state after the lock gear and the retainer are engaged together.FIGS. 5(A) and 5(B)are vertical cross sections of the side wall62econstituting the protruding portion62cillustrated inFIG. 2(A)when viewed from the outside of the retainer62. Throughout the drawings, components that are the same as those of the above-described first embodiment are denoted by the same symbols and not described repeatedly.

A seat belt retractor1according to the second embodiment of the present invention includes engagement teeth61d, which are engageable with the vehicle sensor5, on the outer surface of the outer circumferential wall61aof the lock gear61and an engagement portion62f, which are engageable with the engagement teeth61d, on at least part of the inner surface of the side wall62eof the retainer62. InFIGS. 5(A) and 5(B), the outer circumferential wall61aand the inner circumferential wall62aare filled with gray for convenience of illustration.

As illustrated, the engagement portion62fhas a shape of teeth engageable with the engagement teeth61d. The circumferential pitch of the teeth constituting the engagement portion62fmay be the same as or shorter than the pitch of the engagement teeth61d. Making the circumferential pitch of the teeth constituting the engagement portion62fshorter than the circumferential pitch of the engagement teeth61dallows the eccentric lock gear61to become quickly engaged with the retainer62. The engagement portion62fis formed at, for example, a portion of the side wall62ethat touches the outer circumferential wall61awhen the lock gear61becomes eccentric in the webbing pull-out direction F.

As illustrated inFIG. 5(A), in the normal state, specifically, for example, when the webbing is free from a hard pulling force in the webbing pull-out direction F, the spool2is not moved relative to the base frame3(not eccentrically located), a predetermined gap is left (in a non-engagement state) between the engagement inner teeth61bof the lock gear61and the engagement outer teeth62bof the retainer62.

On the other hand, as illustrated inFIG. 5(B), for example, when the spool2is pulled hard in the webbing pull-out direction F, the spool2moves upward inFIG. 5(B)and becomes eccentric relative to the base frame3. Thus, the lock gear61also moves upward inFIG. 5(B)and becomes eccentric in association with the movement of the spool2, whereby the engagement teeth61dof the lock gear61and the engagement portion62fof the retainer62touch one another (become engaged together).

Referring now toFIGS. 6(A) to 6(C), modified examples of the seat belt retractor1according to the above-described second embodiment are described below. Here,FIGS. 6(A) to 6(C)illustrate modified examples of the seat belt retractor illustrated inFIGS. 5(A) and 5(B), whereFIG. 6(A)illustrates a first modified example,FIG. 6(B)illustrates a second modified example, andFIG. 6(C)illustrates a third modified example. Each drawing illustrates only the side wall62eviewed in the same direction as in the case ofFIG. 5(A)and omits illustrations of other components as they are the same as those in the above-described embodiment.

The first modified example illustrated inFIG. 6(A)includes the engagement portion62fformed at a portion of the side wall62ethat touches the outer circumferential wall61awhen the lock gear61becomes eccentric in a direction F′ in which the reaction force caused in the spool2at activation of the pretensioner7is exerted. The second modified example illustrated inFIG. 6(B)includes the engagement portions62fformed at two portions of the side wall62ethat touch the outer circumferential wall61awhen the lock gear61becomes eccentric in the webbing pull-out direction F or in the direction F′ in which the reaction force caused in the spool2at activation of the pretensioner7is exerted. The third modified example illustrated inFIG. 6(C)includes the engagement portion62fformed over substantially the entire area of the side wall62ecovering the outer circumferential wall61a.

In this manner, the engagement portion62fcan be formed as needed on any direction to which the spool2possibly moves and becomes eccentric relative to the base frame3. The above described second embodiment (including the modified examples) illustrates the case where the side wall62edefines a space accommodating both of the lock gear61and the vehicle sensor5. However, a space accommodating the lock gear61and a space accommodating the vehicle sensor5may be separately formed. In this case, the side wall62ethat defines a space accommodating the lock gear61is disposed so as to cover the entire circumference of the outer circumferential wall61aof the lock gear61, and thus the engagement portion62fmay be formed over the entire circumference of the inner surface of the side wall62e.

Referring now toFIG. 7, a seat belt device according to an embodiment of the present invention is described below. Here,FIG. 7is a diagram of the entire configuration of a seat belt device according to an embodiment of the present invention. InFIG. 7, components other than the seat belt device are drawn with dot-and-dash lines for convenience of illustration.

A seat belt device100according to an embodiment illustrated inFIG. 7includes a webbing W that restrains an occupant, a seat belt retractor1that retracts the webbing W, a guide anchor101that is disposed on the vehicle body and that guides the webbing W, a belt anchor102that fixes the webbing W to the vehicle body, a buckle103that is disposed on the side surface of a seat S on which the occupant is seated, and a tongue104that is disposed on the webbing W. The seat belt retractor1has such a configuration as illustrated inFIG. 1toFIG. 6(C).

Components other than the seat belt retractor1are briefly described below. The seat S includes, for example, a seat portion S1on which the occupant is seated, a backrest portion S2located on the back of the occupant, and a headrest portion S2that supports the head of the occupant. The seat belt retractor1is installed in, for example, the B pillar P of a vehicle body.

Generally, the buckle103is often disposed on the side surface of the seat portion S1and the belt anchor102is often disposed on the undersurface of the seat portion S1. The guide anchor101is often disposed on the B pillar P. The webbing W has one end connected to the belt anchor102and the other end connected to the seat belt retractor1with the guide anchor101interposed therebetween.

When the tongue104is to be fitted into the buckle103, the webbing W is pulled out from the seat belt retractor1while slidably moving through an insertion hole of the guide anchor101. When an occupant wears the seat belt or unfastens the seat belt when getting off the vehicle, the webbing W is retracted until it receives a predetermined load by the operation of the spring unit4of the seat belt retractor1.

The seat belt device100above-described has a configuration formed by installing the seat belt retractor1according to the above-described embodiment in a normal seat belt device on the front seat. However, the seat belt retractor1may be installed in a seat belt device on the rear seat while the guide anchor101is omitted.

The present invention is not limited to the above-described embodiments and may be modified in various manners within the scope not departing from the gist of the present invention, for example, the present invention may be applied to a seat belt device used in transportations other than vehicles.