Webbing winding device

In a webbing winding device, a sub-torsion shaft is inserted from one side in the axial direction of a spool into the spool when assembling the sub-torsion shaft to the spool. Subsequently, by the sub-torsion shaft rotating in the winding direction, movement of the sub-torsion shaft with respect to the spool in the winding direction and in one side in the axial direction is inhibited. Subsequently, by a stopper being fitted from one side in the axial direction into insertion groove portions, movement of the sub-torsion shaft with respect to the spool in the pull out direction is inhibited. Accordingly, since the direction in which the sub-torsion shaft is assembled to the spool becomes only a direction parallel to the axial direction of the spool, the assembility of the sub-torsion shaft with respect to the spool may be improved.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 from Japanese Patent Application No. 2011-136391 filed Jun. 20, 2011, the disclosure of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a webbing winding device in which a spool is provided with a torsion shaft.

2. Related Art

In a webbing winding device disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2001-225719, a torsion bar is inserted into a reel along the axial direction of the reel so as to disable the relative rotation between the reel and the torsion bar. Furthermore, a holder member is press-inserted into the reel directed along the radial direction of the reel, so a second torque transmitting portion of the torsion bar comes into contact with the holder member so as to disable the separation of the torsion bar from the reel.

However, in the webbing winding device, as described above, the direction in which the torsion bar is inserted into the reel becomes the axial direction of the reel, but the direction in which the holder member is press-inserted into the reel becomes the radial direction of the reel. For this reason, in order to assemble the torsion bar to the reel, the torsion bar and the holder member need to be assembled to the reel in the intersection directions. As a result, the assembility is poor.

SUMMARY OF THE INVENTION

The invention has been made in view of the above-described circumstances, and it is desirable to provide a webbing winding device capable of improving assembility of a torsion shaft with respect to a spool.

According to a first aspect, there is provided a webbing winding device including: a spool that is formed in a cylindrical shape and is rotatable; an insertion groove portion that is formed at an inner peripheral portion of the spool and extends in an axial direction of the spool; an engagement groove portion that is formed at the inner peripheral portion of the spool, communicates with the insertion groove portion and extends from the insertion groove portion toward one side in a rotation direction of the spool; a torsion shaft that is coaxially provided inside the spool; an engaged portion that is integrally formed with the torsion shaft, and is configured such that the engaged portion is inserted from one side in the axial direction of the spool into the insertion groove portion and is rotated from an inside of the insertion groove portion toward the one side in the rotation direction so as to engage with the engagement groove portion, whereby movement of the engaged portion with respect to the spool toward the one side in the rotation direction and the one side in the axial direction is inhibited; and an inhibiting portion that is fitted from the one side in the axial direction into the insertion groove portion and inhibits movement of the engaged portion with respect to the spool toward the other side in the rotation direction of the spool.

In the webbing winding device according to the first aspect, the spool is formed in a cylindrical shape so as to be rotatable. The inner peripheral portion of the spool is provided with the insertion groove portion and the engagement groove portion. The insertion groove portion extends in the axial direction of the spool so as to communicate with the engagement groove portion, and the engagement groove portion extends from the insertion groove portion toward the one side in the rotation direction of the spool. Furthermore, the torsion shaft is coaxially formed inside the spool.

Here, the engaged portion is integrally formed with the torsion shaft. The engaged portion is inserted from the one side in the axial direction of the spool into the insertion groove portion, and is rotated from the inside of the insertion groove portion toward the one side in the rotation direction of the spool so as to engage with the engagement groove portion. Accordingly, the movement of the engaged portion with respect to the spool toward the one side in the rotation direction and the one side in the axial direction is inhibited. Furthermore, the inhibiting portion is fitted from the one side in the axial direction of the spool into the insertion groove portion, and the movement of the engaged portion with respect to the spool toward the other side in the rotation direction of the spool is inhibited.

For this reason, the torsion shaft is inserted from the one side in the axial direction of the spool into the spool when assembling the torsion shaft to the spool. Subsequently, by the torsion shaft being rotated toward the one side in the rotation direction, the movement of the torsion shaft with respect to the spool toward the one side in the rotation direction and the one side in the axial direction is inhibited. Subsequently, by the inhibiting portion being fitted from the one side in the axial direction of the spool into the insertion groove portion, the movement of the torsion shaft with respect to the spool toward the other side in the rotation direction is inhibited. Accordingly, the torsion shaft is assembled to the spool so as not to be separable therefrom. Accordingly, the direction in which the torsion shaft is assembled to the spool becomes only a direction parallel to the axial direction of the spool.

According to a second aspect, there is provided the webbing winding device according to the first aspect, wherein the inhibiting portion is provided at the torsion shaft so as to be movable in an axial direction of the torsion shaft and be rotatable about an axis of the torsion shaft.

In the webbing winding device according to the second aspect, since the inhibiting portion is provided at the torsion shaft, the torsion shaft can be assembled to the spool while the inhibiting portion is sub-assembled with the torsion shaft. Further, the inhibiting portion is configured to be movable in the axial direction of the torsion shaft and to be rotatable about the axis of the torsion shaft. For this reason, the inhibiting portion and the insertion groove can be easily aligned with each other by rotating the inhibiting portion about the axis of the torsion shaft before the inhibiting portion is fitted into the insertion groove. Furthermore, the torsion shaft serves as a guide member when fitting the inhibiting portion into the insertion groove, so that the inhibiting portion can be moved along the axial direction of the torsion shaft.

According to a third aspect, there is provided the webbing winding device according to the first aspect or the second aspect, wherein the one side in the rotation direction corresponds to a winding direction in which a webbing is wound on the spool.

In the webbing winding device according to the third aspect, the one side in the rotation direction corresponds to the winding direction of the spool. For this reason, the engaged portion (the torsion shaft) engages with the engagement groove portion (the spool) in the winding direction. In other words, the engagement groove portion (the spool) engages with the engaged portion (the torsion shaft) in the opposite direction (the pull out direction) to the winding direction. Accordingly, the rotation of the torsion shaft is inhibited at the time of the rapid deceleration or the like of the vehicle, so that the torsion shaft is twisted, and accordingly when the rotation of the spool in the pull out direction is permitted (that is, when the force limiter mechanism is operated), the direction in which the engagement groove portion (the spool) engages with the engaged portion (the torsion shaft) is equal to the rotation direction of the spool. Accordingly, the operation of the force limiter mechanism is not affected by the inhibiting portion.

According to a fourth aspect, there is provided the webbing winding device according to any one of the first aspect to the third aspect, further including: a fastened member that is formed in a cylindrical shape, and is arranged at the one side in the axial direction with respect to the inhibiting portion so as to be integrally rotatable with the torsion shaft, the torsion shaft being disposed inside the fastened member; and a fastening member that is threaded into an end portion of the torsion shaft at the one side in the axial direction, and comes into contact with the fastened member so as to fasten the fastened member to the spool.

In the webbing winding device according to the fourth aspect, the fastened member formed in a cylindrical shape is disposed at the one side of the axial direction of the spool with respect to the inhibiting portion so as to be integrally rotatable with the torsion shaft, and the torsion shaft is disposed inside the fastened member. Further, the fastening member is threaded into the end portion of the torsion shaft at the one side in the axial direction, and the fastening member comes into contact with the fastened member so as to fasten the fastened member to the spool.

For this reason, since the movement of the inhibiting portion toward the one side in the axial direction of the spool is inhibited by the fastened member, the inhibiting portion can be made reliably so as not to be separated from the spool. Furthermore, since the position of the fastening member is set to the position where the fastening member comes into contact with the fastened member, when the fastening member is threaded into the torsion shaft, the axial force in the one side in the axial direction of the spool acts on the torsion shaft. Accordingly, the engaged portion and the engagement groove portion are fastened to each other by the axial force.

In the above aspects, it is possible that a fitting portion extending along the axial direction is provided at the inhibiting portion.

In the above aspects, it is possible that plural insertion groove portions, the engagement groove portions, the engaged portions and fitting portions are provided.

In the above aspects, it is possible that the engaged portions are provided at the torsion shaft and the fitting portions are provided at the inhibiting portion so as to correspond to positions of the insertion groove portions at the inner peripheral portion of the spool in a circumferential direction.

According to the webbing winding device of the first aspect, the assembility of the torsion shaft to the spool can be improved.

According to the webbing winding device of the second aspect, the assembility of the torsion shaft to the spool can be further improved.

According to the webbing winding device of the third aspect, the inhibiting portion can be provided without affecting the operation of the force limiter mechanism.

According to the webbing winding device of the fourth aspect, the inhibiting portion can be reliably made so as not to be separable from the spool, and the engaged portion can be fastened to the engagement groove portion.

DETAILED DESCRIPTION OF THE INVENTION

InFIG. 1, a main part of a webbing winding device10according to an embodiment of the invention is illustrated by an exploded perspective view.

As illustrated in this drawing, a webbing winding device10includes a frame12. The frame12includes a plate-like back plate14which is fixed to a vehicle body. Leg pieces16and18extend in the substantially perpendicular direction from both end portions of the back plate14in the width direction, and the frame12is formed in a substantially recess shape in the top view. Furthermore, an existing lock mechanism (not shown in the drawings) is attached to the outside of the leg piece18.

A substantially cylindrical spool20is formed between the leg piece16and the leg piece18of the frame12. The spool20is disposed so that the axial direction becomes the opposing direction of the leg piece16and the leg piece18, and is rotatably supported to the frame12through a main torsion shaft52, a sub-torsion shaft64, and the like to be described later.

A base end portion of an elongated stripe-like webbing40is caught (anchored) to the spool20. When the spool20rotates in the winding direction (the direction indicated by the arrow A illustrated inFIG. 1) which corresponds to one side in the rotation direction, the webbing40is wound thereon from the base end side thereof so as to be accommodated. Further, when the webbing40wound on the spool20is reeled out, the spool20rotates in the pull out direction (the direction indicated by the arrow B illustrated inFIG. 1, and in a broad sense, understood as the ‘other side in the rotation direction’).

As illustrated inFIG. 2, a penetration hole22penetrates the axis center portion of the spool20. The portion of the penetration hole22at one side in the axial direction of the spool20(the direction indicated by the arrow C illustrated inFIG. 1and the like) is formed as a sub-torsion shaft accommodating portion24which accommodates a sub-torsion shaft64to be described later, and the portion of the penetration hole22at the other side in the axial direction of the spool20(the direction indicated by the arrow D illustrated inFIG. 1and the like) is formed as a main torsion shaft accommodating portion26which accommodates a main torsion shaft52to be described later.

As illustrated inFIGS. 3 and 4, the portion of the sub-torsion shaft accommodating portion24at the other side in the axial direction of the spool20is formed so as to be smaller in diameter than the portion of the sub-torsion shaft accommodating portion24at one side in the axial direction of the spool20. At the portion of the sub-torsion shaft accommodating portion24, plural (in the embodiment, four) insertion groove portions28are provided. The insertion groove portions28are formed in a substantially trapezoid shape when seen from one side in the axial direction of the spool20, and are opened inward in the radial direction of the spool20. Further, the insertion groove portions28are arranged at a predetermined interval therebetween along the circumferential direction of the spool20, and extend along the axial direction of the spool20.

Further, at the sub-torsion shaft accommodating portion24of the spool20, plural (in the embodiment, four) engagement groove portions30are provided. Each engagement groove portion30extends from the insertion groove portion28along the winding direction of the spool20, and is opened inward in the radial direction of the spool20. Further, each engagement groove portion30communicates with the portion of the insertion groove portion28at the other side in the axial direction of the spool20. Furthermore, the engagement groove portion30is configured such that the engagement groove portion30does not extend from the insertion groove portion28which is communicated to the engagement groove portion30to the adjacent insertion groove portion28. Accordingly, a surface of the engagement groove portion30at one side in the axial direction of the spool20is formed as an axial catching (anchoring) surface32, and a surface of the engagement groove portion30at the side in the winding direction of the spool20is formed as a circumferential catching (anchoring) surface34. The axial catching surface32and the engagement groove portion30are formed so as to be engageable with an engaged protrusion66A of the sub-torsion shaft64to be described later.

As illustrated inFIG. 2, the main torsion shaft accommodating portion26of the spool20is provided with an engagement portion36which fixes the main torsion shaft52to be described later in the portion at one side in the axial direction of the spool20, and the engagement portion36is formed in a spline shape.

A lock gear42is disposed at the other side in the axial direction of the spool20so as to be coaxial with the spool20. A gear portion44is formed on the outer peripheral portion of the lock gear42. Further, a penetration hole46which penetrates in the axial direction is formed in the axis center portion of the lock gear42, and a spline-like engagement portion48is formed on the inner peripheral portion of the penetration hole46.

In an emergency of a vehicle (at a predetermined moment such as rapid deceleration), the lock mechanism is operated by detecting a state where the acceleration of the vehicle (especially, the reducing-acceleration (catching (anchoring)) is a predetermined acceleration or more or the pull-out acceleration of the webbing40from the spool20is a specific acceleration or more, the lock member (not shown in the drawings) of the lock mechanism engages with a gear portion44of the lock gear42, so that the rotation of the lock gear42in the pull out direction (in the direction indicated by the arrow B ofFIG. 1) is inhibited (locked).

As illustrated inFIG. 1, a force limiter mechanism50is provided inside the penetration hole22of the spool20. The force limiter mechanism50includes the shaft-like main torsion shaft52, and the main torsion shaft52is accommodated inside the main torsion shaft accommodating portion26of the spool20. The main torsion shaft52are disposed so as to be coaxial with the spool20and the lock gear42, and is inserted into the penetration hole46of the lock gear42. In the main torsion shaft52, a spline-like first attachment portion54is formed at the center portion in the length direction, and a spline-like second attachment portion56is formed in the end portion at one side in the axial direction (the direction indicated by the arrow C illustrated inFIG. 1) in the same way. Further, the second attachment portion56is provided with a columnar shaft portion58, and the shaft portion58protrudes from the second attachment portion56toward one side in the axial direction of the main torsion shaft52(seeFIG. 2).

By the first attachment portion54engaging with the engagement portion48of the lock gear42, the main torsion shaft52is fixed to the lock gear42so as to be rotatable together. Further, by the second attachment portion56engaging with the engagement portion36of the spool20, the main torsion shaft52is fixed to the spool20so as to be rotatable together. Furthermore, the shaft portion58protrudes into the sub-torsion shaft accommodating portion24.

A portion of the main torsion shaft52between the first attachment portion54and the second attachment portion56is configured as a first energy absorbing portion59which absorbs the kinetic energy of a passenger pulling out of the webbing40as described below.

A trigger wire60is formed at the side portion of the main torsion shaft52. A base end portion60A of the trigger wire60is inserted into a hole portion49which is formed at the outside in the radial direction in relation to the penetration hole46of the lock gear42so as to be caught to the lock gear42. On the other hand, the tip end side of the trigger wire60in relation to the base end portion60A is inserted into the hole portion38which is formed in the spool20in parallel to the penetration hole22, and a tip end portion40B protrudes from the spool20toward one side in the axial direction.

The shaft-like sub-torsion shaft64serving as the torsion shaft constituting the force limiter mechanism50is accommodated in the sub-torsion shaft accommodating portion24of the spool20. The sub-torsion shaft64is disposed so as to be coaxial with the main torsion shaft52, and the portion of the sub-torsion shaft64at one side in the axial direction (the direction indicated by the arrow C illustrated inFIG. 1) protrudes from one end of the axial direction of the spool20.

The end portion of the sub-torsion shaft64at the other side in the axial direction (the direction indicated by the arrow D illustrated inFIG. 1) is provided with a substantially disk-like first attachment portion66, and the first attachment portion66is formed so as to be insertable into the sub-torsion shaft accommodating portion24. The outer peripheral portion of the first attachment portion66is provided with plural (in the embodiment, four) engaged protrusions66A which serve as engaged portions and have a substantially trapezoid cross-section, and the engaged protrusions66A protrude from the outer peripheral portion of the first attachment portion66outward in the radial direction of the first attachment portion66. Further, the engaged protrusions66A are arranged at a predetermined interval in the circumferential direction of the first attachment portion66so as to correspond to the insertion groove portions28, and are formed so as to be insertable into the insertion groove portions28. In addition, the engaged protrusion66A is disposed inside the engagement groove portion30of the spool20, and engages with the axial catching surface32and circumferential catching surface34of the engagement groove portion30(seeFIG. 6B). Accordingly, the movement of the sub-torsion shaft64toward one side in the axial direction and the winding direction (the direction indicated by the arrow A illustrated inFIG. 1) is inhibited.

The end portion of the sub-torsion shaft64at one side in the axial direction is provided with a spline-like second attachment portion68. The portion of the sub-torsion shaft64between the first attachment portion66and the second attachment portion68is configured as a second energy absorbing portion70which absorbs the kinetic energy of a passenger pulling out the webbing40as described below, and the second energy absorbing portion70is formed in a shaft shape having a circular cross-section.

A resinous stopper80serving as an inhibiting portion is provided at the second energy absorbing portion70. The stopper80includes an annular main body portion82which is partially opened, and the second energy absorbing portion70is inserted into the main body portion82, so that the stopper80is assembled to the sub-torsion shaft64. Further, the stopper80is configured so as to be movable with respect to the sub-torsion shaft64in the axial direction of the sub-torsion shaft64, and is configured to be rotatable about the axis of the sub-torsion shaft64.

The outer peripheral portion of the main body portion82is integrally provided with plural (in the embodiment, four) fitting pins84which have a substantially trapezoid cross-section. The fitting pins84are arranged at a predetermined interval along the circumferential direction of the main body portion82so as to correspond to the insertion groove portions28, and extend along the axial direction of the sub-torsion shaft64. Further, the fitting pin84is fitted into the insertion groove portion28of the spool20, and is disposed at the side of the engaged protrusion66A which is at the pull out direction (the direction indicated by the arrow B ofFIG. 6C) side so as to stop (catch) the engaged protrusion66A in the pull out direction. Accordingly, the movement (the rotation) of the engaged protrusion66A in the pull out direction is inhibited by the fitting pin84, and the sub-torsion shaft64is fixed to the spool20so as to be rotatable together.

As illustrated inFIG. 2, a substantially disk-like washer90is provided between the sub-torsion shaft64and the main torsion shaft52inside the engagement groove portions30of the spool20, and the shaft portion58of the main torsion shaft52penetrates the washer90.

Furthermore, a substantially disk-like stopper push92is provided between the sub-torsion shaft64and the washer90inside the engagement groove portions30of the spool20. The center portion of the stopper push92protrudes toward the sub-torsion shaft64, and the shaft portion58of the main torsion shaft52is fitted into the center portion.

As illustrated inFIG. 1, a sleeve96serving as a fastened member is provided at the stopper80at one side in the axial direction of the sub-torsion shaft64. The sleeve96is formed in a substantially cylindrical shape, and is disposed so as to be coaxial with the sub-torsion shaft64. A penetration hole98which penetrates in the axial direction is formed in the axis center portion of the sleeve96, and the sub-torsion shaft64is loosely inserted into the penetration hole98. Further, a spline-like engagement portion100is formed in the inner peripheral portion at one side in the axial direction of the sleeve96(in the direction indicated by the arrow C illustrated inFIG. 1), and the second attachment portion68of the sub-torsion shaft64engages with the engagement portion100. Accordingly, the sleeve96is fixed to the sub-torsion shaft64so as to be rotatable together.

Furthermore, a screw110is provided at one side in the axial direction of the sub-torsion shaft64. The screw110includes a screw portion112and a push portion114which is larger in diameter than the screw portion112. The screw portion112is threaded into a screw hole65which is formed in the tip end portion of the sub-torsion shaft64, so that the screw110is fixed to the tip end portion of the sub-torsion shaft64. Further, in this way, in a state where the screw110is fixed to the tip end portion of the sub-torsion shaft64, the push portion114comes into contact with one end of the sleeve96at one side in the axial direction. Accordingly, the sleeve96is fastened to the spool20, and the movement of the sleeve96and the stopper80with respect to the sub-torsion shaft64toward one side in the axial direction is restricted.

Furthermore, a clutch mechanism and a switching mechanism (not shown in the drawings) are provided at the side of the leg piece16of the frame12, and the clutch mechanism is connected to the sleeve96. Further, the clutch mechanism is configured to be operated in a manner such that the tip end portion40B of the trigger wire60is pulled toward the other side in the axial direction of the spool20with respect to the hole portion38. Furthermore, when the clutch mechanism is operated, the clutch mechanism is connected to the switching mechanism, and the rotation of the sleeve96is transmitted to the switching mechanism through the clutch mechanism.

The switching mechanism is configured to switch between a state in which the transmitted rotation is inhibited and a state in which the rotation is permitted, and is connected to a control device (not shown in the drawings), so that the switching mechanism is operated by the control device. Then, the switching mechanism inhibits the transmitted rotation (so that the sleeve96is not rotatable) before the switching mechanism is operated, and the switching mechanism permits the transmitted rotation (so that the sleeve96is rotatable) when the switching mechanism is operated.

Further, the control device is electrically connected to a collision detecting unit (not shown in the drawings). The collision detecting unit predicts the collision of the vehicle through, for example, an acceleration sensor which detects the acceleration (especially rapid deceleration) of the vehicle or a distance measuring sensor which detects the distance up to the obstacle in front of the vehicle. Further, the collision detecting unit is configured to detect the collision of the vehicle in a manner such that the acceleration sensor detects the collision acceleration larger than or equal to a predetermined reference value.

Furthermore, the control device is electrically connected to a body shape detecting unit (not shown in the drawings), and the body shape detecting unit detects the body shape of the passenger sitting on a seat through, for example, a load sensor, a belt sensor, a seat position sensor, or the like. Specifically, the load sensor detects the load acting on the seat of the vehicle, and the body shape detecting unit detects the body shape of the passenger based on the detected load. Further, the belt sensor detects the pull out amount of the webbing40from the spool20, and the body shape detecting unit detects the body shape of the passenger based on the detected pull out amount. Furthermore, the seat position sensor includes a position detecting sensor which detects the slide position in the front-back direction of the seat of the vehicle or a camera sensor which is formed in the interior of the vehicle, and the body shape detecting unit detects the body shape of the passenger based on the position of the seat detected by the seat position sensor.

Then, in a case in which the control device determines that the body shape of the passenger is less than a predetermined reference value based on the signal from the body shape detecting unit, and the collision of the vehicle occurs based on the signal from the collision detecting unit, the switching mechanism is operated by the control device.

Here, the webbing winding device10according to the embodiment is configured to be operated as below.

That is, the spool20, the lock gear42, the main torsion shaft52, the sub-torsion shaft64, and the sleeve96are configured to be rotatable together in the winding direction and the pull out direction.

When the webbing40is pulled out from the spool20, the webbing40is mounted on the body of the passenger of the vehicle.

In a state where the webbing40is mounted on the body of the passenger of the vehicle, for example, when the vehicle is rapidly decelerated and the lock mechanism is operated, the rotation of the lock gear42in the pull out direction is inhibited.

Accordingly, the rotation of the spool20connected to the lock gear42through the main torsion shaft52in the pull out direction is restricted, so that the webbing40is restricted from being pulled out from the spool20. Accordingly, the body of the passenger which is about to move in the front direction of the vehicle is restrained by the webbing40.

Further, when the body of the passenger pulls put the webbing40by the larger force while the rotation of the lock gear42in the pull out direction is inhibited, and the rotational force of the spool20in the pull out direction based on this tensile force becomes larger than the anti-twisting load (the anti-deformation load) of the first energy absorbing portion59of the main torsion shaft52, the force limiter mechanism50is operated, so that the rotation of the spool20in the pull out direction with a load which is larger than or equal to the force limiter load (the anti-twisting load of the first energy absorbing portion59) is permitted by the twisting (the deformation) of the first energy absorbing portion59.

Accordingly, when the spool20rotates in the pull out direction by the twisting of the first energy absorbing portion59so that the webbing40is pulled out from the spool20, the load (the burden) on the chest of the passenger by the webbing40is reduced, and the kinetic energy of the passenger pulling (stretching) of the webbing40is absorbed by the twisted amount of the first energy absorbing portion59.

On the other hand, as described above, the state in which the spool20rotates in the pull out direction with respect to the lock gear42corresponds to the state in which the lock gear42relatively rotates in the winding direction with respect to the spool20. Accordingly, when the lock gear42relatively rotates in the winding direction with respect to the spool20, the base end portion60A of the trigger wire60moves in the circumferential direction of the main torsion shaft52while the tip end side in relation to the base end portion60A of the trigger wire60is inserted in the hole portion38of the spool20, the tip end portion40B of the trigger wire60is stretched (pulled) toward the other side in the axial direction of the spool20with respect to the hole portion38.

Accordingly, the clutch mechanism is operated, so that the clutch mechanism and the switching mechanism are connected to each other. For this reason, the rotation of the sleeve96is transmitted to the switching mechanism through the clutch mechanism. In this state, since the rotation of the sleeve96is disabled by the switching mechanism, the body of the passenger stretches (pulls out) the webbing40by the larger force in this state. When the rotational force of the spool20in the pull out direction based on the tensile force becomes larger than the sum of the anti-twisting load (the anti-deformation load) of the first energy absorbing portion59of the main torsion shaft52and the anti-twisting load (the anti-deformation load) of the second energy absorbing portion70of the sub-torsion shaft64, the rotation in the pull out direction with a load which is larger than or equal to the force limiter load of the spool20(the sum of the anti-twisting load of the first energy absorbing portion59and the anti-twisting load of the second energy absorbing portion70) is permitted by the twisting (the deformation) of the first energy absorbing portion59and the second energy absorbing portion70.

Accordingly, when the spool20rotates in the pull out direction by the twisting of the first energy absorbing portion59and the second energy absorbing portion70so that the webbing40is pulled out from the spool20, the load (the burden) on the chest of the passenger by the webbing40is reduced, and the kinetic energy of the passenger pulling (stretching) of the webbing40is absorbed by the twisted amount of the first energy absorbing portion59and the second energy absorbing portion70.

On the other hand, in a case in which the control device determines that the body shape of the passenger is less than a predetermined reference value based on the signal from the body shape detecting unit and the collision of the vehicle occurs based on the signal of the collision detecting unit, the switching mechanism is operated by the control device. For this reason, since the rotation of the sleeve96is permitted (so that the sleeve96is rotatable), the second energy absorbing portion70is not twisted. Accordingly, the rotation of the spool20in the pull out direction with a load which is larger than or equal to the force limiter load (the anti-twisting load of the first energy absorbing portion59) is permitted by the twisting (the deformation) of the first energy absorbing portion59.

That is, in a case in which the body shape of the passenger is larger than or equal to a predetermined reference value, the force limiter load becomes high so as to become the sum of the anti-twisting load of the first energy absorbing portion59and the anti-twisting load of the second energy absorbing portion70. On the other hand, in a case in which the body shape of the passenger is less than a predetermined reference value and the collision of the vehicle is detected, the force limiter load becomes low so as to become the anti-twisting load of the first energy absorbing portion59. For this reason, the passenger can be appropriately protected in accordance with the body shape.

Next, the operation and the effect of the embodiment will be described by describing the procedure of assembling the sub-torsion shaft64to the spool20.

At the time when the sub-torsion shaft64is assembled to the spool20, the main torsion shaft52has already assembled to the spool20, and the washer90and the stopper push92are arranged inside the sub-torsion shaft accommodating portion24.

First, as illustrated inFIG. 5A, the second energy absorbing portion70of the sub-torsion shaft64is inserted from the opening portion of the main body portion82of the stopper80into the main body portion82, so that the stopper80is assembled to the second energy absorbing portion70. Accordingly, the stopper80and the sub-torsion shaft64are formed as a sub-assembly, the stopper80is relatively movable in the axial direction of the sub-torsion shaft64with respect to the sub-torsion shaft64, and is relatively rotatable about the axis of the sub-torsion shaft64.

In this state, the sub-torsion shaft64is inserted from one side in the axial direction of the spool20into the sub-torsion shaft accommodating portion24of the spool20(seeFIG. 5B). At this time, the first attachment portion66of the sub-torsion shaft64is inserted through the sub-torsion shaft accommodating portion24, and the engaged protrusion66A of the sub-torsion shaft64are inserted through the insertion groove portions28of the spool20(seeFIG. 6A). Then, the engaged protrusion66A reaches the portion of the insertion groove portion28at the other side in the axial direction of the spool20, thereafter, the sub-torsion shaft64is rotated in the winding direction (the sub-torsion shaft is rotated in the direction indicated by the arrow A in the state ofFIG. 5C). Accordingly, the engaged protrusions66A are disposed inside the engagement groove portions30of the spool20(the engaged protrusion66A is disposed from the state illustrated inFIG. 6Ato the state illustrated inFIG. 6B), so that the engaged protrusion66A engages with the axial catching surface32and circumferential catching surface34of the engagement groove portion30. Accordingly, the movement of the sub-torsion shaft64toward one side in the axial direction and the winding direction is inhibited. Furthermore, in this state, since the washer90and the stopper push92are arranged inside the sub-torsion shaft accommodating portion24, the movement of the sub-torsion shaft64toward the outside in the axial direction is restricted.

Subsequently, the stopper80is rotated about the axis of the sub-torsion shaft64so as to align the fitting pins84of the stopper80to the insertion groove portions28of the spool20, and the stopper80is moved toward the other side of the sub-torsion shaft64in the axial direction (from the state ofFIG. 7Ato the state ofFIG. 7B). Accordingly, the fitting pin84is fitted into the insertion groove portion28(seeFIG. 6C) so as to be disposed at the side of the engaged protrusion66A which is at the pull out direction, so that the fitting pin84stops (catches) the engaged protrusion66A. Accordingly, since the rotation of the engaged protrusion66A in the pull out direction is restricted by the fitting pin84, the rotation of the sub-torsion shaft64in the pull out direction is inhibited.

Then, the sleeve96is inserted from one side in the axial direction of the spool20into the sub-torsion shaft accommodating portion24, and the sub-torsion shaft64is disposed inside the sleeve96.

In this state, the screw110is threaded into the screw hole65of the sub-torsion shaft64. Accordingly, the push portion114of the screw110comes into contact with the sleeve96, so that the sleeve96is fastened to the spool20. Further, at this time, the position of the screw110in the axial direction of the spool20is set to the position of one end side of the sleeve96in the axial direction. For this reason, when the screw110is threaded into the sub-torsion shaft64, the axial force acts on the sub-torsion shaft64in one side in the axial direction, so that the engaged protrusion66A of the sub-torsion shaft64is fastened to the axial catching surface32of the spool20by the axial force. With the above-described configuration, the sub-torsion shaft64is assembled to the spool20so as not to be separable therefrom.

In this way, at the time of assembling the sub-torsion shaft64to the spool20, the sub-torsion shaft64is inserted from one side in the axial direction of the spool20into the spool20. Subsequently, by rotating the sub-torsion shaft64in the winding direction, the movement of the sub-torsion shaft64toward one side in the axial direction and the winding direction with respect to the spool20is inhibited. Subsequently, by the stopper80being fitted from one side in the axial direction of the spool20into the insertion groove portions28, the movement of the sub-torsion shaft64in the pull out direction with respect to the spool20is inhibited. Accordingly, the sub-torsion shaft64is assembled to the spool20so as not to be separable therefrom. Accordingly, the direction in which the sub-torsion shaft64is assembled to the spool20becomes only a direction parallel to the axial direction of the spool20. With the above-described configuration, the assembility of the sub-torsion shaft64to the spool20may be improved.

Further, since the stopper80is provided at the sub-torsion shaft64, the sub-torsion shaft64can be assembled to the spool20in a state where the stopper80and the sub-torsion shaft64are made as a sub-assembly (the stopper80is sub-assembled to the sub-torsion shaft64). Accordingly, the assembility of the sub-torsion shaft64to the spool20can be further improved.

Furthermore, the stopper80is configured to be movable in the axial direction of the sub-torsion shaft64and be rotatable about the axis of the sub-torsion shaft64. For this reason, when the stopper80is rotated about the axis of the sub-torsion shaft64before the fitting pin84of the stopper80is fitted into the insertion groove portion28, the positions of the fitting pin84and the insertion groove portion28can be easily aligned with each other. Furthermore, the sub-torsion shaft64serves as a guide member at the time of fitting the fitting pin84into the insertion groove portion28, so that the stopper80can be moved along the axial direction of the sub-torsion shaft64.

Further, the engaged protrusion66A of the sub-torsion shaft64engages with the circumferential catching surface34of the spool20in the winding direction. In other words, circumferential catching surface34engages with the engaged protrusion66A in the pull out direction. Accordingly, at a time when the force limiter mechanism50is operated (at a time when the sub-torsion shaft64is twisted), the direction in which the engagement groove portion30engages with the engaged protrusion66A is equal to the rotation direction (the pull out direction) of the spool20. Accordingly, the stopper80can be provided without affecting the operation of the force limiter mechanism50.

Furthermore, as described above, the sleeve96is disposed at one side in the axial direction of the spool20with respect to the stopper80, and the sub-torsion shaft64is disposed inside the sleeve96. Further, the screw110is threaded into the screw hole65of the sub-torsion shaft64, and the screw110comes into contact with the sleeve96, so that the sleeve96is fastened to the spool20. For this reason, since the movement of the stopper80toward one side in the axial direction of the spool20is inhibited by the sleeve96, it is possible to reliably prevent the stopper80from being separated from the spool20.

Furthermore, since the position of the screw110in the axial direction of the spool20is set to the position of the one end of the sleeve96in the axial direction, by the screw110being threaded into the sub-torsion shaft64, the axial force in the axial direction one side acts on the sub-torsion shaft64. Accordingly, the engaged protrusion66A and the engagement groove portion30can be fastened to each other by the axial force, and further the sub-torsion shaft64may be fastened to the spool20.

Further, the engaged protrusion66A of the sub-torsion shaft64engages with the axial catching surface32and circumferential catching surface34of the engagement groove portion30, and the fitting pin84of the stopper80stops (catches) the engaged protrusion66A. Accordingly, since the sub-torsion shaft64is not separable from the spool20after the fitting pin84of the stopper80is fitted into the insertion groove portion28, the assembility at the time of assembling the sleeve96and assembling the clutch mechanism from this state can be improved.

Furthermore, the second energy absorbing portion70of the sub-torsion shaft64is inserted from the opening portion of the main body portion82of the stopper80into the main body portion82, so that the stopper80is assembled to the second energy absorbing portion70. For this reason, the stopper80is attachable to and detachable from the sub-torsion shaft64. Accordingly, the stopper80can be easily made to be a sub-assembly in the sub-torsion shaft64, and the assembility of the sub-torsion shaft64to the spool20can be further improved.

Furthermore, in the embodiment, although the invention is applied to the assembly structure of the spool20and the sub-torsion shaft64, the invention may be applied to the assembly structure of the spool20and the main torsion shaft52. Further, the invention may be applied to the torsion shaft in which the main torsion shaft52and the sub-torsion shaft64are integrated with each other. That is, the invention may be applied to the torsion shaft provided inside the spool20.

Further, in the embodiment, each installation number of the insertion groove portions28, the engagement groove portions30, the engaged protrusions66A, and the fitting pins84is four, but the number may be one or more.

Furthermore, in the embodiment, when the control device determines that the body shape of the passenger is less than a predetermined reference value based on the signal from the body shape detecting unit and determines that the collision of the vehicle occurs based on the signal of the collision detecting unit, the switching mechanism is operated by the control device, but the timing at which the switching mechanism is operated may be arbitrarily set. For example, when the control device determines that the body shape of the passenger is less than a predetermined reference value and determines that the collision of the vehicle occurs, the switching mechanism may be operated after a predetermined specific time is elapsed.

Further, as described above, in the embodiment, when the control device determines that the body shape of the passenger is less than a predetermined reference value and that the collision of the vehicle occurs, the switching mechanism is operated by the control device. Instead of this configuration, the switching mechanism may be operated by the control device when the control device determines that the acceleration of the vehicle is less than a predetermined reference value based on the signal of the collision detecting unit and that the collision of the vehicle occurs. Accordingly, the load value of the force limiter load may be switched in accordance with the acceleration of the vehicle.