JP7356856B2 - Seatbelt retractor and seatbelt device - Google Patents

Description

The present invention relates to a seatbelt retractor and a seatbelt device, and particularly to a seatbelt retractor and a seatbelt device equipped with an energy absorption mechanism including a plurality of torsion bars.

2. Description of the Related Art Vehicles such as automobiles are generally provided with a seat belt device that restrains an occupant on a seat that includes a seat portion on which the occupant sits and a backrest portion located on the back of the occupant. Such a seatbelt device includes webbing for restraining an occupant, a seatbelt retractor for retracting the webbing, a buckle placed on the side of the seat, and a tongue placed on the webbing, and the tongue is fitted into the buckle. By doing so, the webbing restrains the occupant to the seat.

Here, it has become common for seatbelt retractors to include a pretensioner that removes slack in the webbing in an emergency such as a vehicle collision. Further, the seat belt retractor is often equipped with an energy absorption mechanism for reducing the load associated with forward movement of the occupant after the pretensioner is activated.

For example, Patent Document 1 discloses a two-stage load limiting device that is disposed in the flow of force between the locking device and the belt shaft and that allows the belt webbing to be pulled out during load limiting. An arrangement is disclosed in which the limiting device includes a first load limiting element having a high load limiting level and a second load limiting element having a low load limiting level. The two-stage load limiting device also includes a third load limiting element acting in parallel with the second load limiting element to compensate for temporary force reductions when load limiting levels are switched.

Further, Patent Document 2 discloses a first energy absorbing member that absorbs energy due to a rotation difference between the spool and the lock mechanism, a first energy transmitting member attached to one end side of the first energy absorbing member, and a first energy absorbing member that absorbs energy due to a rotation difference between the spool and the lock mechanism. An energy absorption mechanism is disclosed that includes a second energy transmission member that meshes with the transmission member, and a second energy absorption member that absorbs energy due to a rotational difference between the second energy transmission member and the spool.

Special table 2013-500191 publication International Publication No. 2015/076377

As described in Patent Document 1 mentioned above, it is known that the limit load temporarily drops when the load level of the energy absorption mechanism is switched from a high load to a low load. By arranging a third load-limiting element constituted by a plurality of shearable structural elements supporting each other in the force flow between the locking device and the belt shaft, This suppresses the drop in limit load.

Here, the energy absorption mechanism described in Patent Document 1 is one in which a torsion bar forming a first load limiting element and a torsion bar forming a second load limiting element are arranged in series. The energy absorption mechanism described in Patent Document 2 is one in which a torsion bar that constitutes a first energy absorption member and a torsion bar that constitutes a second energy absorption member are arranged in parallel.

When a torsion bar is used as an energy absorbing member, the amount of energy absorbed depends on the amount of torsional deformation of the torsion bar, so the length and thickness of the torsion bar are important factors. As described in Patent Document 1, when torsion bars are arranged in series, the width of the seatbelt retractor increases as the torsion bars become longer, so there is a problem that there is little adjustment margin for the amount of energy absorption. be. On the other hand, in the invention described in Patent Document 2, since two types of torsion bars are arranged in parallel, there is a margin for adjustment in the length direction.

Furthermore, as described above, the energy absorption mechanism described in Patent Document 1 and the energy absorption mechanism described in Patent Document 2 are different in the arrangement method of the torsion bar, so the energy absorption mechanism described in Patent Document 1 is The third load limiting element cannot be applied to the energy absorption mechanism described in Patent Document 2.

The present invention has been devised in view of such problems, and provides a sheet that can suppress a drop in limit load when switching load levels even with an energy absorption mechanism having a configuration in which torsion bars are arranged in parallel. An object of the present invention is to provide a belt retractor and a seat belt device.

According to the present invention, there is provided a spool for winding up webbing for restraining an occupant, a locking mechanism for regulating the rotation of the spool in the direction of pulling out the webbing in an emergency, and a locking mechanism for controlling the load applied to the webbing when the locking mechanism is activated. an energy absorption mechanism that absorbs the occupant's kinetic energy by restricting the kinetic energy of the occupant, the energy absorption mechanism being disposed on the central axis of the spool, and having a first end connected to the locking mechanism. a first torsion bar, which is fixed to the spool, and whose second end is configured to be able to engage with or disengage from the spool; a second torsion bar, the second end of which is configured to be rotatable around the axis of the first torsion bar, and when the second end of the second torsion bar starts rotating around the axis of the first torsion bar; a load adding member that temporarily increases the load input to the second torsion bar , the load adding member being fixed to the spool and attached to the shaft on the second end side of the first torsion bar. There is provided a seatbelt retractor comprising a link plate through which the second torsion bar can be inserted and which rotatably supports the second end of the second torsion bar.

Further, the link plate includes an opening formed in the center and a weakened part formed on the outer periphery of the opening, and the opening has serrations formed on the first torsion bar side. It may be inserted.

Further, the link plate may have a protrusion that can be engaged with a component that causes a rotation difference with the spool when the second torsion bar starts rotating.

Further, a plurality of the second torsion bars may be arranged at equal intervals along the outer periphery of the first torsion bar.

Further, according to the present invention, there is provided a seat belt device characterized by having a seat belt retractor having the above-described configuration.

According to the seat belt retractor and seat belt device according to the present invention described above, by arranging the load adding member in the energy absorption mechanism, when the load level of the energy absorption mechanism is switched from a high load to a low load, the second The load input to the torsion bar can be temporarily increased. Therefore, even with an energy absorption mechanism having a configuration in which torsion bars are arranged in parallel, it is possible to suppress a drop in the limit load when changing the load level.

FIG. 1 is a exploded view of parts showing a seatbelt retractor according to an embodiment of the present invention. 2(A) is a perspective view, and FIG. 2(B) is a sectional view taken along line BB in FIG. 2(A). FIG. 3A is a partially enlarged view showing a state where the load level of the energy absorption mechanism is low; FIG. 3A is a perspective view, and FIG. 3B is a sectional view taken along the line BB in FIG. FIG. 3 is a partially enlarged view showing a load applying member. FIG. 3 is a diagram showing the action of the load applying member, in which (A) shows an initial stage, (B) an intermediate stage of plastic deformation, and (C) a final stage of plastic deformation. FIG. 3 is a diagram showing the effect of the energy absorption mechanism, in which (A) shows the conventional technology and (B) shows the present embodiment. FIG. 7 is a partially enlarged view showing a modification of the load applying member. FIG. 3 is a diagram showing the effect of a deformation example of a load-applying member, in which (A) shows an initial stage, (B) shows a plastic deformation start stage, (C) shows a plastic deformation intermediate stage, and (D) shows a plastic deformation end stage. ing. 1 is an overall configuration diagram showing a seat belt device according to an embodiment of the present invention.

Embodiments of the present invention will be described below using FIGS. 1 to 9. Here, FIG. 1 is a exploded view of parts showing a seatbelt retractor according to an embodiment of the present invention. FIG. 2 is a partially enlarged view showing a state where the load level of the energy absorption mechanism is high, where (A) is a perspective view and (B) is a sectional view taken along the line BB in FIG. 2(A). . FIG. 3 is a partially enlarged view showing a state where the load level of the energy absorption mechanism is low, where (A) is a perspective view and (B) is a sectional view taken along the line BB in FIG. 3(A). .

As shown in FIG. 1, a seatbelt retractor 1 according to an embodiment of the present invention includes a spool 2 that winds up webbing for restraining an occupant, and a pretensioner 3 that winds up the webbing to remove slack in an emergency. a locking mechanism 4 that restricts the rotation of the spool 2 in the webbing pulling direction in an emergency; and an energy absorption mechanism 5 that absorbs the kinetic energy of the occupant by limiting the load applied to the webbing when the locking mechanism 4 is activated. It is equipped with Note that in FIG. 1, the illustration of the webbing is omitted.

The spool 2 is a winding drum that winds up the webbing, and is rotatably housed within a base frame 11 that forms the skeleton of the seat belt retractor 1. Further, for example, the pretensioner 3 and the lock mechanism 4 are arranged on the first end 21 side of the spool 2, and the energy absorption mechanism 5 and the spring unit 6 are arranged on the second end 22 side.

The pretensioner 3 includes a paddle gear 31 connected to the spool 2 and a power transmission device 32 that transmits power to the paddle gear 31 in an emergency. Note that the configuration of the pretensioner 3 is not limited to the illustrated configuration. The paddle gear 31 is fixed to an intermediate portion of a shaft portion 41 a of a locking base 41 , and the shaft portion 41 a of the locking base 41 is fixed to the spool 2 . Further, a bearing plate 23 may be arranged between the paddle gear 31 and the spool 2.

The power transmission device 32 includes, for example, a power transmission member (not shown) that transmits power to the paddle gear 31, a cylindrical guide member 33 that guides the power transmission member to the paddle gear 31, and a working gas inside the guide member 33. and a cover member 35 that forms a passage for a power transmission member around the outer periphery of the paddle gear 31.

In this embodiment, since the paddle gear 31 is arranged inside the base frame 11, the cover member 35 is arranged on the inner surface of the base frame 11, and the lock mechanism 4 is arranged on the outer surface of the base frame 11. A retainer cover 43 is arranged to accommodate the parts.

Note that when the paddle gear 31 is arranged outside the base frame 11, the cover member 35 is arranged on the outer surface of the base frame 11, and a part of the lock mechanism 4 is arranged outside the cover member 35. A retainer cover 43 for accommodating is arranged.

In an emergency such as a vehicle collision, working gas is supplied from the gas generator 34 into the guide member 33, and the power transmission member moves along the guide member 33. The power transmission member released from the guide member 33 collides with the engagement teeth of the paddle gear 31, causing the paddle gear 31 to rotate. The rotation of the paddle gear 31 rotates the spool 2 to wind up the webbing, removes slack in the webbing, and restrains the occupant to the seat.

The locking mechanism 4 includes, for example, a locking base 41 fixed to the spool 2, a lock gear 42 disposed adjacent to the locking base 41, and a retainer cover 43 that accommodates the lock gear 42. A vehicle sensor (not shown) may be disposed on the retainer cover 43 to detect sudden deceleration or inclination of the vehicle body. Note that the configuration of the lock mechanism 4 is not limited to the illustrated configuration.

The locking base 41 includes a shaft portion 41a fixed to the spool 2, and a flange portion 41b having a pawl (not shown) that can engage with internal teeth formed in the opening of the base frame 11. .

An insertion hole 41c for fixing the first torsion bar is formed in the center of the shaft portion 41a. Further, the outer periphery of the shaft portion 41a is formed in a polygonal shape, and the paddle gear 31, the bearing plate 23, and the first end portion 21 of the spool 2 are inserted through and fixed to this portion.

A pawl is arranged on the flange portion 41b so as to be able to protrude and retract outward in the radial direction. The pawl is housed within the outer diameter of the flange portion 41b when the lock mechanism 4 is not in operation. Furthermore, when the lock mechanism 4 is activated, the pawl projects radially outward beyond the outer diameter of the flange portion 41b and engages with internal teeth formed in the opening of the base frame 11. By engaging the pawl with the base frame 11 in this manner, rotation of the locking base 41 in the webbing pulling direction can be restricted.

The lock gear 42 includes a swingable flywheel (not shown), and when the webbing is pulled out faster than the normal withdrawal speed, the flywheel swings and forms the webbing on the retainer cover 43. engages the internal teeth. Furthermore, when the vehicle sensor is activated, the lever of the vehicle sensor engages with external teeth formed on the side surface of the lock gear 42.

In this way, the rotation of the lock gear 42 is regulated by the operation of the flywheel or vehicle sensor. When the rotation of the lock gear 42 is restricted, relative rotation occurs between the locking base 41 and the lock gear 42, and the pawl moves radially outward from the flange portion 41b of the locking base 41 due to this relative rotation. stand out.

The energy absorption mechanism 5 is arranged, for example, on the central axis of the spool 2, a first end 51a is fixed to the lock mechanism 4, and a second end 51b is configured to be able to engage with or disengage from the spool 2. The first torsion bar 51 is arranged parallel to the first torsion bar 51, the first end 52a is fixed to the spool 2, and the second end 52b is configured to be rotatable around the axis of the first torsion bar 51. The second torsion bar 52, the switching mechanism 53 that switches the power transmission path from the spool 2 to the energy absorption mechanism 5, and the second end 52b of the second torsion bar 52 start rotating around the axis of the first torsion bar 51. It is provided with a load adding member (link plate 54) that increases the load input to the second torsion bar 52 when doing so.

The first torsion bar 51 is, for example, a rod-shaped metal member, and is an energy absorbing member that is plastically deformed by being twisted due to the rotation difference between the first end 51a and the second end 51b, and absorbs kinetic energy. . A cavity is formed in the center of the spool 2 into which the first torsion bar 51 is inserted. The first torsion bar 51 acts when the load level of the energy absorption mechanism 5 is high.

The first end 51a of the first torsion bar 51 is inserted into the insertion hole 41c of the locking base 41, and is fixed to the locking base 41 so as to be rotatable in synchronization with the locking base 41. The second end 51b of the first torsion bar 51 is pivotally supported by a spring core (not shown) of the spring unit 6, and is wound with webbing by a mainspring spring (not shown) built into the spring unit 6. It is biased in the direction of removal.

Further, a center gear 51c is fixed to the second end 51b side of the first torsion bar 51, and a bush 51d, a bearing 51e, and a push nut 51f are inserted between the center gear 51c and the spring core. You can leave it there. The center gear 51c is a component that transmits power between the first torsion bar 51 and the second torsion bar 52.

The second torsion bar 52 is, for example, a rod-shaped metal member, and is an energy absorbing member that is plastically deformed by being twisted due to the difference in rotation between the first end 52a and the second end 52b, and absorbs kinetic energy. . A cavity for inserting the second torsion bar 52 and a fixing hole 24 for fixing the second torsion bar 52 are formed in the outer circumference of the spool 2 . The second torsion bar 52 acts when the load level of the energy absorption mechanism 5 is low. Therefore, the second torsion bar 52 usually has a shape that is thinner and shorter than the first torsion bar 51.

Further, a plurality of second torsion bars 52 are arranged along the outer periphery of the first torsion bar 51 at equal intervals. In this embodiment, since two second torsion bars 52 are arranged, the two second torsion bars 52 are arranged at positions on both sides with the first torsion bar 51 in between. Note that the number of second torsion bars 52 is arbitrary, and may be one or three or more.

The first end 52a of the second torsion bar 52 is inserted into the fixing hole 24 of the spool 2 and fixed to the spool 2 so as to be rotatable in synchronization with the spool 2. Further, the second end portion 52b of the second torsion bar 52 is rotatably supported by the link plate 54. The link plate 54 is a component that is fixed to the spool 2, allows insertion of the shaft portion on the second end 51b side of the first torsion bar 51, and rotatably supports the second end 52b of the second torsion bar 52. .

Specifically, the link plate 54 is, for example, a plate member having a substantially cross-shaped outer shape, and has a first opening 54a in the center through which the shaft on the second end 51b side of the first torsion bar 51 is inserted. A second opening 54b is formed on both sides of the first opening 54a, through which the second end 52b of the second torsion bar 52 is inserted.

Further, a recessed portion matching the outer shape of the link plate 54 is formed in the second end portion 22 of the spool 2 . By inserting the link plate 54 into this recess, the link plate 54 is fixed to the spool 2. At this time, the shaft portion of the first torsion bar 51 on the second end 51b side is inserted into the first opening 54a, and the second end 52b of the second torsion bar 52 is inserted into the second opening 54b.

Furthermore, a round gear 52c that rotates while meshing with the center gear 51c is fixed to the second end 52b side of the second torsion bar 52. The center gear 51c and the round gear 52c constitute a so-called planetary gear mechanism.

The switching mechanism 53 includes, for example, an engagement plate 53a connected to the first torsion bar 51, a release ring 53b configured to be able to be locked to the engagement plate 53a, and a ring holder 53c that slidably holds the release ring 53b. , and a power generating device 53d that slides the release ring 53b in the axial direction of the spool 2.

The engagement plate 53a is fixed to the shaft portion of the center gear 51c, and is fixed to the first torsion bar 51 via the center gear 51c. Further, on the outer edge of the engagement plate 53a, four concave portions 53e that are open outward are formed at equal intervals in the circumferential direction.

The release ring 53b includes an annular portion 53f having a large opening in the center, and a plurality of claws 53g extending from the inner edge of the annular portion 53f in a direction away from the spool 2. A planetary gear mechanism and a link plate 54 arranged at the second end 22 of the spool 2 are arranged inside the annular portion 53f. The claws 53g are arranged, for example, at four locations at equal intervals in the circumferential direction of the annular portion 53f, and are configured to be inserted into recesses 53e formed in the engagement plate 53a.

The ring holder 53c is a component that guides the movement of the spool 2 in the axial direction while suppressing interference between the release ring 53b and the planetary gear mechanism. The ring holder 53c has a substantially cap shape, and includes, for example, a cylindrical portion 53h that surrounds the outer periphery of the planetary gear mechanism, and an annular disk portion 53i that covers the outer periphery of the link plate 54.

An end of the cylindrical portion 53h opposite to the disk portion 53i is fixed to the second end 22 of the spool 2. A release ring 53b is slidably inserted into the outer peripheral surface of the cylindrical portion 53h. Moreover, a groove for guiding the claw 53g may be formed on the outer circumferential surface of the cylindrical portion 53h. Further, a plurality of protrusions for positioning the engagement plate 53a may be formed on the surface of the disc portion 53i.

The power generation device 53d includes, for example, a gas generator 53j that instantaneously generates working gas, a piston 53k driven by the working gas, a lever 53m driven by the piston 53k, and guides the movement of the piston 53k and the lever 53m. It includes a housing 53n that can hold the lever 53m, and a lever stopper 53p that holds the lever 53m at its initial position. The housing 53n includes a substantially cylindrical cylinder portion 53q and a body portion 53r formed to surround the outer periphery of the lever 53m.

A piston 53k is inserted into the cylinder part 53q, and a gas generator 53j is arranged at the rear end of the cylinder part 53q. A guide groove 53s for moving the lever 53m in a direction approaching the spool 2 while rotating the lever 53m is formed on the inner circumferential surface of the body portion 53r.

The lever 53m includes a ring portion 53t that can come into contact with the annular portion 53f of the release ring 53b, and a protrusion 53u that can come into contact with the piston 53k. A convex portion inserted into the guide groove 53s is formed on the outer peripheral surface of the ring portion 53t.

Here, the operation of the switching mechanism 53 will be explained with reference to FIGS. 1 to 3(B). In the initial state, the lever 53m is held at a position away from the spool 2 by the lever stopper 53p. At this time, as shown in FIGS. 2(A) and 2(B), the release ring 53b is also held at a position away from the spool 2, and the claw 53g is locked in the recess 53e of the engagement plate 53a. There is.

In this initial state, since the spool 2 and the first torsion bar 51 are connected, the power transmission path is as shown by the dotted line in FIG. 2(B): spool 2 → ring holder 53c → release The ring 53b → the engagement plate 53a → the bearing 51e → the center gear 51c → the first torsion bar 51 → the locking base 41 (fixed) → the base frame 11 (fixed). Therefore, since the limit load of the webbing is regulated by the first torsion bar 51, the load level of the energy absorption mechanism 5 is set to a high load.

When the gas generator 53j operates, the piston 53k moves along the cylinder portion 53q, and the tip of the piston 53k protrudes from the tip of the cylinder portion 53q. The piston 53k pushes away the protrusion 53u of the lever 53m, and the lever 53m moves in a direction approaching the spool 2 while rotating along the guide groove 53s.

Due to this axial movement of the lever 53m, the ring portion 53t comes into contact with the annular portion 53f of the release ring 53b, and the release ring 53b moves in a direction closer to the spool 2. This movement of the release ring 53b causes the claw 53g to disengage from the recess 53e of the engagement plate 53a, and the locked state of the release ring 53b is released, as shown in FIGS. 3(A) and 3(B).

In this final state, since the connection between the spool 2 and the first torsion bar 51 is released, the power transmission path is from the spool 2 to the second torsion bar 51 as shown by the dotted line in FIG. It is composed of bar 52 → round gear 52c → center gear 51c (fixed) → first torsion bar 51 (fixed) → locking base 41 (fixed) → base frame 11 (fixed). Therefore, since the limit load of the webbing is regulated by the second torsion bar 52, the load level of the energy absorption mechanism 5 is set to a low load.

The load applying member will be explained below with reference to FIGS. 4 to 6(B). Here, FIG. 4 is a partially enlarged view showing the load applying member. FIG. 5 is a diagram showing the action of the load applying member, in which (A) shows the initial stage, (B) the intermediate stage of plastic deformation, and (C) the final stage of plastic deformation.

In this embodiment, the load applying member is constituted by a link plate 54. Specifically, the link plate 54 includes a first opening 54a formed in the center and a weak portion 54c formed around the outer periphery of the first opening 54a. The first opening 54a has an uneven shape in the circumferential direction.

The fragile portion 54c is formed, for example, by a slit formed along the outer periphery of the first opening 54a. Note that the fragile portion 54c is not limited to the illustrated configuration, but may be configured such that the outer peripheral portion of the first opening 54a can be plastically deformed. For example, the fragile portion 54c may be formed by a small hole or a recess.

Further, the shaft portion of the bearing 51e connected to the first torsion bar 51 is formed with serrations 51g that conform to the irregularities of the first opening 54a. The serrations 51g are inserted through the first opening 54a. Note that the component on which the serrations 51g are formed is not limited to the bearing 51e, but may be the first torsion bar 51, the shaft of the center gear 51c, or the like.

The link plate 54 functions as a load adding member when the second torsion bar 52 acts as the energy absorption mechanism 5, that is, when the load level of the energy absorption mechanism 5 is low. At this time, since the connection between the first torsion bar 51 and the spool 2 is released, even if a load is applied to the spool 2 in the direction of pulling out the webbing, the first torsion bar 51 and the parts connected thereto (For example, the center gear 51c, the bearing 51e, etc.) remain fixed.

On the other hand, the second torsion bar 52 has a first end 52a fixed to the spool 2, and a second end 52b rotatable around the axis of the first torsion bar 51.

Therefore, when a load is applied to the spool 2 in the direction of pulling out the webbing, as shown in FIG. 2 maintains a non-rotating state. Note that the clockwise arrow shown in FIGS. 5(A) to 5(C) indicates the rotation direction of the spool 2.

Then, when the load in the direction of pulling out the webbing exceeds the limit load of the second torsion bar 52 (including the load increase due to the load adding member), as shown in FIG. The end portion 52b begins to rotate, and the second torsion bar 52 is twisted due to the difference in rotation with the first end portion 52a, causing the spool 2 to rotate. At this time, as illustrated, the first torsion bar 51, center gear 51c, and bearing 51e remain fixed.

Therefore, the link plate 54 rotates due to the rotation of the spool 2, the first opening 54a of the link plate 54 interferes with the serration 51g, and the fragile portion 54c is plastically deformed. That is, the load applying member (link plate 54) is caused by the load input to the second torsion bar 52 when the second end 52b of the second torsion bar 52 starts rotating around the axis of the first torsion bar 51. It is configured to be plastically deformable.

Finally, as shown in FIG. 5(C), the first opening 54a is deformed into a circular shape having the same diameter as the outer diameter of the serrations 51g, so that they do not interfere with each other. In this way, the load applying member (link plate 54) functions at the initial stage when the second torsion bar 52 starts rotating.

Here, FIG. 6 is a diagram showing the effect of the energy absorption mechanism, in which (A) shows the prior art and (B) shows the present embodiment. In each of FIGS. 6(A) and 6(B), the horizontal axis represents time (s), and the vertical axis represents the load (N) applied to the occupant.

First, the operation of the energy absorption mechanism 5 common to the conventional technology and this embodiment will be explained using FIG. 6(A). In an emergency such as a vehicle collision, the locking mechanism 4 is activated to lock the rotation of the spool 2 in the direction of pulling out the webbing, and at approximately the same time, the pretensioner 3 is activated to remove slack in the webbing. This state is defined as time 0.

Thereafter, although the occupant's upper body attempts to move forward due to inertial force, the webbing is not pulled out, so the load applied to the occupant gradually increases over time. Then, at time t1, the first torsion bar 51 begins to twist. The kinetic energy of the occupant is absorbed by this twisting, and the load applied to the occupant is kept approximately constant.

Thereafter, the load level of the energy absorption mechanism 5 may be switched from high load to low load due to interaction with the airbag device. Now, assume that the load level of the energy absorption mechanism 5 is switched at time t2. Simultaneously with this switching, the load applied to the occupant decreases, and at time t3, the second torsion bar 52 begins to twist, and the load applied to the occupant is maintained substantially constant.

In a seatbelt retractor equipped with a conventional energy absorption mechanism that does not have a load applying member, as shown in FIG. 6(A), when the load level of the energy absorption mechanism 5 is switched from high load to low load, The limit load will temporarily drop (see the range α surrounded by the dotted line in the figure).

On the other hand, in the seatbelt retractor 1 equipped with the energy absorption mechanism 5 of this embodiment having a load adding member (link plate 54), as shown in FIG. 6(B), the load input to the second torsion bar 52 is can be temporarily increased by the load adding member (link plate 54) to compensate for the load in the shaded portion in the figure, and it is possible to suppress a temporary drop in the limit load.

Next, modifications of the load applying member will be described with reference to FIGS. 7 to 8(D). Here, FIG. 7 is a partially enlarged view showing a modification of the load applying member. FIG. 8 is a diagram showing the action of a modified example of the load-applying member, in which (A) is the initial stage, (B) is the plastic deformation start stage, (C) is the plastic deformation intermediate stage, and (D) is the plastic deformation end. It shows the stages.

In a modification of the load applying member shown in FIG. 7, the link plate 54 has a protrusion 54d that can be locked to the engagement plate 53a. A locking hole 53v for locking the tip of the projection 54d is formed in the engagement plate 53a. The protrusion 54d is configured to be plastically deformable due to the rotation difference between the link plate 54 and the engagement plate 53a. Note that the number and arrangement of the protrusions 54d are arbitrary and are not limited to the illustrated configuration.

Since the link plate 54 is fixed to the spool 2 and the engagement plate 53a is fixed to the first torsion bar 51, the engagement plate 53a has a rotation difference with the spool 2 when the second torsion bar 52 starts rotating. It is a component that occurs.

As shown in FIG. 8(A), in the initial stage, the protrusion 54d is inserted into the locking hole 53v. Then, when the load level of the energy absorption mechanism 5 is switched from a high load to a low load, the link plate 54 becomes rotatable.

When the load in the webbing pulling direction exceeds the limit load of the second torsion bar 52, the link plate 54 rotates in the direction of the arrow in the figure, as shown in FIG. 8(B), and the protrusion 54d closes in the locking hole 53v collide with Thereafter, as the link plate 54 continues to rotate in the direction of the arrow in the figure, the protrusion 54d is plastically deformed as shown in FIG. 8(C). Finally, as shown in FIG. 8(D), the protrusion 54d separates from the locking hole 53v.

Therefore, even when such a load applying member (link plate 54) is used, the load input to the second torsion bar 52 is applied to the load applying member (link plate 54), similarly to the seat belt retractor 1 according to the present embodiment described above. The limit load can be temporarily increased by the link plate 54), and a temporary drop in the limit load can be suppressed.

In addition, in the above-mentioned modification, the case where the protruding part 54d of the link plate 54 is locked to the engagement plate 53a is explained, but the protruding part 54d is connected to the spool 2 when the second torsion bar 52 starts rotating. It may also be locked to other components that cause a rotational difference.

Next, a seat belt device according to an embodiment of the present invention will be described with reference to FIG. Here, FIG. 9 is an overall configuration diagram showing a seat belt device according to an embodiment of the present invention. In addition, in FIG. 9, for convenience of explanation, components other than the seat belt device are illustrated with dashed lines.

A seatbelt device 100 according to the present embodiment shown in FIG. 9 includes a webbing W for restraining an occupant, a seatbelt retractor 1 for retracting the webbing W, and a guide anchor 101 provided on the vehicle body side for guiding the webbing W. The seat belt retractor 1 includes, for example, a belt anchor 102 for fixing the webbing W to the vehicle body side, a buckle 103 disposed on the side surface of the seat S, and a tongue 104 disposed on the webbing W. It has the configuration shown in .

Components other than the seat belt retractor 1 will be briefly described below. The seat S includes, for example, a seat portion S1 on which an occupant sits, a backrest portion S2 located on the back of the occupant, and a headrest portion S3 that supports the occupant's head. The seat belt retractor 1 is built into, for example, a B-pillar R of a vehicle body. Further, in general, the buckle 103 is often arranged on the side surface of the seat portion S1, and the belt anchor 102 is often arranged on the lower surface of the seat portion S1. Further, the guide anchor 101 is often arranged on the B pillar R. The webbing W has one end connected to the belt anchor 102 and the other end connected to the seat belt retractor 1 via the guide anchor 101.

Therefore, when the tongue 104 is fitted into the buckle 103, the webbing W is pulled out from the seat belt retractor 1 while sliding through the insertion hole of the guide anchor 101. Furthermore, when the occupant wears a seatbelt or releases the seatbelt when getting out of the vehicle, the webbing W is wound up by the action of the spring unit 6 of the seatbelt retractor 1 until a certain load is applied.

The seat belt device 100 described above is an ordinary seat belt device for a front seat to which the seat belt retractor 1 according to the embodiment described above is applied. Therefore, according to the seat belt device 100 according to the present embodiment, the load input to the second torsion bar 52 can be temporarily increased by the load adding member (link plate 54), and the temporary limit load can be increased. Depression can be suppressed.

Note that the seat belt device 100 according to this embodiment is not limited to application to front seats, and can be easily applied to rear seats by omitting the guide anchor 101, for example. Furthermore, the seat belt device 100 according to this embodiment can be used in vehicles other than vehicles.

It goes without saying that the present invention is not limited to the embodiments described above, and that various changes can be made without departing from the spirit of the present invention.

1 Seat belt retractor 2 Spool 3 Pretensioner 4 Lock mechanism 5 Energy absorption mechanism 6 Spring unit 11 Base frame 21 First end 22 Second end 23 Bearing plate 24 Fixing hole 31 Paddle gear 32 Power transmission device 33 Guide member 34 Gas generation Container 35 Cover member 41 Locking base 41a Shaft 41b Flange 41c Insertion hole 42 Lock gear 43 Retainer cover 51 First torsion bar 51a First end 51b Second end 51c Center gear 51d Bush 51e Bearing 51f Push nut 51g Serrations 52 Second torsion bar 52a First end 52b Second end 52c Round gear 53 Switching mechanism 53a Engage plate 53b Release ring 53c Ring holder 53d Power generator 53e Recess 53f Annular part 53g Claw 53h Cylindrical part 53i Disc part 53j Gas generation Container 53k Piston 53m Lever 53n Housing 53p Lever stopper 53q Cylinder part 53r Body part 53s Guide groove 53t Ring part 53u Projection part 53v Locking hole 54 Link plate (load adding member)
54a First opening 54b Second opening 54c Weak portion 54d Projection 100 Seatbelt device 101 Guide anchor 102 Belt anchor 103 Buckle 104 Tong

Claims (5)

a spool for winding up webbing for restraining an occupant; a locking mechanism for restricting the rotation of the spool in the webbing pulling direction in an emergency; and a locking mechanism for restricting the load applied to the webbing when the locking mechanism is activated. A seatbelt retractor comprising: an energy absorption mechanism that absorbs kinetic energy of the seatbelt retractor;
The energy absorption mechanism is
a first torsion bar disposed on the central axis of the spool, a first end fixed to the locking mechanism, and a second end configured to be able to engage with or disengage from the spool;
a second torsion bar that is arranged parallel to the first torsion bar, has a first end fixed to the spool, and a second end configured to be rotatable around the axis of the first torsion bar;
a load adding member that temporarily increases the load input to the second torsion bar when the second end of the second torsion bar starts rotating around the axis of the first torsion bar ;
The load applying member is fixed to the spool, and is configured by a link plate that allows insertion of the shaft portion on the second end side of the first torsion bar and rotatably supports the second end of the second torsion bar. has been,
A seat belt retractor characterized by: The link plate includes an opening formed in the center and a weakened part formed on the outer periphery of the opening, and serrations formed on the first torsion bar side are inserted into the opening. The seat belt retractor according to claim 1 . The seat belt retractor according to claim 1 , wherein the link plate has a protrusion that can be locked to a component that causes a rotation difference with the spool when the second torsion bar starts rotating. The seat belt retractor according to claim 1, wherein a plurality of said second torsion bars are arranged at equal intervals along the outer circumference of said first torsion bar. A seat belt device comprising the seat belt retractor according to any one of claims 1 to 4 .