JP2023047579A - Retractor for seat belt - Google Patents

Abstract

To provide a retractor for a seat belt that can secure rigidity in a length direction of a movement member while reducing resistance caused when an engagement tooth bites into the movement member.SOLUTION: The retractor for a seat belt includes a winding drum and a pretensioner. The pretensioner has a driving wheel 7 having a plurality of engagement teeth 71 sharpened outward in a radial direction arranged in a circumferential direction, which rotates together with the winding drum, and a rod-like movement member that is not engaged with the driving wheel 7 in a normal time and moves toward the driving wheel 7 in an emergency to engage with at least one of the engagement teeth 71, so as to rotate the driving wheel 7 in a winding direction of a webbing. The movement member is bitten by the engagement teeth 71 to plastically deform. Each of the engagement tooth 71 has a gear tooth-like shape whose direction along a rotary shaft of the driving wheel 7 is a width direction. In tooth tips of the engagement teeth 71, one or more concave parts 73 recessed inwardly in the radial direction of the driving wheel 71 are formed at sides closer to inside than both end parts of the tooth tips 72.SELECTED DRAWING: Figure 3

Description

The present invention relates to a seatbelt retractor mounted on a vehicle for pulling out and winding up webbing as a seatbelt.

2. Description of the Related Art Conventionally, a seat belt retractor is known that prevents webbing from being pulled out in an emergency such as a vehicle collision. Some seat belt retractors are equipped with a pretensioner for removing slack in the webbing in an emergency.

Pretensioners have various structures, but in recent years, a pretensioner using a rod-shaped moving member and a drive wheel driven by this moving member has been proposed. For example, Patent Document 1 discloses a seat belt retractor (referred to as a "webbing retractor" in Patent Document 1) 100 as shown in FIG.

Specifically, the seat belt retractor 100 includes a winding drum (referred to as a “spool” in Patent Document 1) 110 rotatable in a webbing winding direction and a webbing drawing-out direction, and a winding drum 110 in the event of a vehicle emergency. It includes a pretensioner 120 that rotates in the take-up direction.

The pretensioner 120 includes a driving wheel (referred to as a "rotating body" in Patent Document 1) 130 that rotates together with the winding drum 110, and a rod-like shape that normally disengages from the driving wheel 130 (Fig. 12 shows its cross-sectional shape). shown). The driving wheel 130 has a plurality of engaging teeth 131 sharpened radially outward and arranged in the circumferential direction. Each engagement tooth 131 has a gear tooth shape whose width direction is along the rotation axis of the driving wheel 130 .

The moving member 140 is disposed within a pipe (not shown), and is moved from within the pipe toward the drive wheel 130 by the pressure of gas supplied from the gas generator in the event of a vehicle emergency to move at least one of the engaging teeth 131 . Engage one. As a result, the driving wheel 130 and the winding drum 110 rotate in the webbing winding direction.

The moving member 140 is made of a material softer than the engaging teeth 131 , and is plastically deformed by the biting of the engaging teeth 131 when engaging with at least one of the engaging teeth 131 . In the seat belt retractor 100 of Patent Document 1, in order to reduce the resistance when the engaging teeth 131 bite into the moving member 140, the thickness of each engaging tooth 131 is increased from both ends to the center. It is formed in a shape that becomes smaller as it goes.

Japanese Patent No. 6620069

However, in the seatbelt retractor 100 of Patent Document 1, the tooth tip of each engaging tooth 131 of the drive wheel 130 is a linear shape parallel to the rotation axis of the drive wheel 130 , so that the engaging tooth 131 does not move toward the moving member 140 . When the moving member 140 is plastically deformed, the rigidity in the longitudinal direction (that is, compression rigidity) of the moving member 140 is reduced, and the efficiency of transmitting the kinetic energy of the moving member to the drive wheels is reduced accordingly.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a seat belt retractor capable of reducing resistance when engaging teeth bite into a moving member and ensuring rigidity in the longitudinal direction of the moving member.

In order to solve the above-described problems, the present invention provides a winding drum that winds up a webbing and is rotatable in a webbing winding direction and a webbing drawing-out direction, and a winding drum that rotates in the winding direction in the event of a vehicle emergency. A drive wheel, which is a pretensioner and rotates together with the winding drum and has a plurality of radially outwardly sharpened engagement teeth arranged in a circumferential direction, and is normally in a non-engagement state with the drive wheel. a rod-shaped moving member that moves toward the driving wheel in an emergency and engages with at least one of the plurality of engaging teeth to rotate the driving wheel in the winding direction of the webbing; and a pretensioner having a pretensioner, wherein when the moving member engages with at least one of the plurality of engaging teeth, the engaging tooth bites into the moving member to plastically deform the engaging teeth, and each of the plurality of engaging teeth has a gear tooth-like shape whose width direction is along the rotation axis of the driving wheel, and the tip of each of the plurality of engaging teeth has, inside the both ends of the tip, Provided is a seat belt retractor characterized in that at least one recessed portion is formed to be recessed radially inwardly of the drive wheel.

According to the above configuration, since the recess is formed in the tip of each engaging tooth, it is possible to reduce the resistance when the engaging tooth bites into the moving member. Moreover, since the plastic deformation of the moving member is suppressed at the position corresponding to the concave portion, the rigidity in the longitudinal direction of the moving member can be ensured. Therefore, the efficiency with which the kinetic energy of the moving member is transmitted to the drive wheels can be improved more than before.

The at least one concave portion may be located on the same circumference in all of the plurality of engaging teeth. According to this configuration, the portion where the rigidity in the longitudinal direction of the moving member is ensured can be made continuous in the longitudinal direction of the moving member. Therefore, the kinetic energy of the moving member is transmitted to the drive wheels more efficiently than when the positions of the concave portions in the width direction of the engaging teeth are shifted between the adjacent engaging teeth.

The at least one recess formed in the tip of each of the plurality of engaging teeth may include a plurality of recesses aligned in the width direction of the engaging teeth. According to this configuration, it is easy to adjust the resistance when the engaging tooth bites into the moving member and the range in which the engaging tooth bites into the moving member.

The moving member has a cross-sectional shape in which the center in the width direction along the rotation axis of the drive wheel swells toward the engaging tooth, and is formed at the tip of each of the plurality of engaging teeth. At least one recess may be centrally located in the tip and the width of the recess may narrow towards the bottom. According to this configuration, it is easy to uniformize the amount of bite of the engaging tooth into the moving member in the width direction of the engaging tooth.

The moving member is pressed against the reaction surface when the engaging tooth bites into the moving member, and the minimum distance from the reaction surface to the bottom of the recess in the radial direction of the drive wheel is may be greater than the thickness of According to this configuration, it is possible to prevent the engaging teeth from biting into the moving member within the recess.

The at least one concave portion formed in at least one engaging tooth among the plurality of engaging teeth may have a shape different from the at least one concave portion formed in another engaging tooth. According to this configuration, it is easy to adjust the resistance when the engaging teeth engage with the moving member and the range in which the engaging teeth bite into the moving member.

According to the present invention, it is possible to secure the rigidity of the moving member in the longitudinal direction while reducing the resistance when the engaging teeth bite into the moving member.

1 is a perspective view of a seat belt retractor according to one embodiment; FIG. (a) and (b) are cross-sectional views taken along line II-II in FIG. 1, (a) showing a normal situation and (b) showing an emergency situation. It is a perspective view of a driving wheel used in the one embodiment. FIG. 3 is a cross-sectional view taken along line IV-IV of FIG. 2; It is a perspective view of the drive wheel of a 1st modification. FIG. 11 is a cross-sectional view of a part of the seat belt retractor when using the driving wheels of the first modified example; FIG. 11 is a cross-sectional view of a part of a seat belt retractor when a drive wheel of a second modified example and a moving member of a modified example are used; FIG. 11 is a cross-sectional view of a part of a seat belt retractor when using a driving wheel of a third modified example and a moving member of a modified example; It is a perspective view of the drive wheel of a 4th modification. FIG. 11 is a cross-sectional view of a part of a seat belt retractor when using a drive wheel of a fourth modified example; It is a perspective view of the drive wheel of a 5th modification. FIG. 10 is a cross-sectional view of a conventional seat belt retractor;

FIG. 1 shows a seat belt retractor 1 according to one embodiment of the present invention. 2(a) and 2(b) are cross-sectional views taken along line II--II in FIG. 1, with (a) showing normal conditions and (b) showing emergency conditions.

A seat belt retractor 1 includes a housing 2 , a winding drum 3 and a pretensioner 4 . The housing 2 is made of sheet metal and includes a pair of side walls facing each other. These side walls are each provided with an opening through which the winding drum 3 is inserted. The take-up drum 3 takes up the webbing 10 and is rotatable in the take-up direction and the draw-out direction of the webbing 10 .

The pretensioner 4 rotates the winding drum 3 in the winding direction in case of vehicle emergency. Specifically, the pretensioner 4 includes a driving wheel 7 that rotates together with the winding drum 3, a rod-shaped moving member 8 that drives the driving wheel 7 in an emergency, a pipe 6 in which the moving member 8 is arranged, and a driving It includes a cover 5 that covers the ring 7 and part of the pipe 6 .

As shown in FIG. 3, the drive wheel 7 has a plurality of engaging teeth 71 arranged in the circumferential direction and pointed radially outward. Each engagement tooth 71 has a gear tooth shape whose width direction is the direction along the rotation axis of the driving wheel 7 .

The tip 72 of each engaging tooth 71 is formed with at least one concave portion 73 recessed inward in the radial direction of the driving wheel 7 inside both end portions of the tip. In the present embodiment, three concave portions 73 are formed in the tip 72 of each engaging tooth 71 and are arranged in the width direction of the engaging tooth 71 . Each recess 73 is a groove with a V-shaped cross section. The number of recesses 73 formed in the tip 72 of each engaging tooth 71 may be one, two, or four or more.

In this embodiment, the concave portions 63 are positioned on the same circumference in all the engaging teeth 71 . In other words, the positions of the recesses 63 in the width direction of the engaging teeth 71 are the same for all the engaging teeth 71 .

The moving member 8 is normally accommodated in the pipe 6 as shown in FIG. In an emergency such as a vehicle collision, the moving member 8 moves from within the pipe 6 toward the driving wheel 7 by the pressure of the gas supplied from the gas generator and engages with at least one of the engaging teeth 71. do. As a result, the drive wheel 7 and the winding drum 3 rotate in the webbing winding direction.

The moving member 8 is made of a material softer than the engaging teeth 71 , and is plastically deformed by the biting of the engaging teeth 71 when engaging with at least one of the engaging teeth 71 . The moving member 8 is pressed against the reaction force surface 9 when the engaging tooth 71 bites into the moving member 8 . In this embodiment, the reaction surface 9 is formed by extending a portion of the pipe 6 . Although the reaction force surface 9 is flat in the illustrated example, the reaction force surface 9 may be a curved surface similar to the cross-sectional shape of the moving member 8 .

The moving member 8 has a width direction along the rotation axis of the driving wheel 7 and a thickness direction along the radial direction of the driving wheel 7 . In this embodiment, as shown in FIG. 4, the cross-sectional shape of the moving member 8 is circular. Therefore, the width and thickness of the moving member 8 are the same. However, the cross-sectional shape of the moving member 8 does not necessarily have to be circular, and may be another shape.

The height of the engaging tooth 71 described above (the distance in the radial direction of the driving wheel 7 from the reference circle passing through the bottom between the engaging teeth 71 to the tooth tip 72) is smaller than the thickness of the moving member 8. is desirable.

As described above, in the seat belt retractor 1 of the present embodiment, the recess 73 is formed in the tip 72 of each engaging tooth 71 of the driving wheel 7 , so that the engaging tooth 71 bites into the moving member 8 . It is possible to reduce the resistance when Moreover, since the plastic deformation of the moving member 8 is suppressed at the position corresponding to the concave portion 73, the rigidity in the longitudinal direction of the moving member 8 can be ensured. Therefore, the efficiency with which the kinetic energy of the moving member 8 is transmitted to the driving wheels 7 can be improved compared to the conventional art.

In addition, in this embodiment, since the concave portions 73 are located on the same circumference in all the engaging teeth 71, the portion where the rigidity in the longitudinal direction of the moving member 8 is secured is the length of the moving member 8. Can be continuous in any direction. Therefore, the kinetic energy of the moving member 8 is transmitted to the drive wheels 7 more efficiently than when the positions of the recesses 73 in the width direction of the engaging teeth 71 are shifted between the adjacent engaging teeth 71, for example.

Furthermore, if a plurality of concave portions are formed in the tip 72 of each engaging tooth 71 as in the present embodiment, resistance when the engaging tooth 71 bites into the moving member 8 and It is easy to adjust the range of biting into 8 (biting depth).

(Modification)
The present invention is not limited to the embodiments described above, and various modifications are possible without departing from the gist of the present invention.

For example, like the drive wheel 7A of the first modified example shown in FIGS. 73 may be formed. 5 and 6, the recess 73 is recessed in an arc shape, and the width of the recess 73 narrows toward the bottom.

The fact that the cross-sectional shape of the moving member 8 is circular as described in the above embodiment can be rephrased as that the moving member 8 has a cross-sectional shape in which the center in the width direction rises toward the engaging teeth 71 .

The widthwise center of the moving member 8 has a cross-sectional shape that swells toward the engaging tooth 71, and the recess 73 positioned in the center of the tooth tip 72 has a width that narrows toward the bottom. Thus, the amount of engagement teeth 71 bite into the moving member 8 can be easily made uniform in the width direction of the engagement teeth 71 .

This effect is obtained when the recessed portion 73 is recessed in a V shape as in the drive wheel 7B of the second modified example shown in FIG. becomes narrower toward the bottom), the sectional shape of the moving member 8 is rectangular on the reaction surface 9 side and semicircular on the engaging tooth 71 side as shown in FIG. 8 has a cross-sectional shape in which the center in the width direction rises toward the engaging teeth 71).

Further, like the driving wheel 7C of the third modified example shown in FIG. It may have a shape different from that of the concave portion 73 indicated by a two-dot chain line in FIG. According to this configuration, it is easy to adjust the resistance when the engaging tooth 71 engages with the moving member 8 and the range (biting depth) in which the engaging tooth 71 bites into the moving member 8 .

Furthermore, like the driving wheel 7D of the fourth modified example shown in FIGS. closest to the reaction surface 9) may be greater than the thickness of the moving member 8. According to this configuration, it is possible to prevent the engaging tooth 71 from biting into the moving member 8 within the concave portion 73 .

When the depth of the concave portion 73 is increased, a portion of the circumferentially continuous slit 74 that crosses all the engaging teeth 71 is partially formed in each of the drive wheels 7E of the fifth modified example shown in FIG. The recess 73 of the engagement tooth 71 may be configured.

REFERENCE SIGNS LIST 1 seat belt retractor 10 webbing 3 winding drum 4 pretensioner 7 drive wheel 71 engagement tooth 72 tooth tip 73 concave portion 74 slit 8 moving member 9 reaction surface

Claims (6)

a winding drum that winds the webbing and is rotatable in a webbing winding direction and a webbing drawing direction;
A pretensioner that rotates the winding drum in the winding direction in the event of a vehicle emergency,
a driving wheel rotating with the winding drum and having a plurality of circumferentially arranged radially outwardly pointed engaging teeth;
Normally, it is in a non-engaged state with the drive wheel, and in an emergency, it moves toward the drive wheel and engages with at least one of the plurality of engagement teeth, thereby displacing the drive wheel with the webbing. and a rod-shaped moving member that rotates in the winding direction of the pretensioner,
When the moving member engages with at least one of the plurality of engaging teeth, it is plastically deformed by the engaging teeth biting into the engaging teeth,
each of the plurality of engagement teeth has a gear-tooth shape with a width direction along the rotation axis of the drive wheel;
The tip of each of the plurality of engaging teeth is formed with at least one concave portion recessed inward in the radial direction of the driving wheel inside both end portions of the tip. seat belt retractor. 2. The seat belt retractor according to claim 1, wherein said at least one recess is located on the same circumference in all of said plurality of engaging teeth. The seatbelt retractor according to claim 1 or 2, wherein the at least one concave portion formed in each tooth tip of the plurality of engaging teeth includes a plurality of concave portions arranged in the width direction of the engaging teeth. The moving member has a cross-sectional shape in which the center in the width direction along the rotation axis of the driving wheel swells toward the engaging tooth,
The at least one recess formed in the tip of each of the plurality of engaging teeth is positioned in the center of the tip, and the width of the recess narrows toward the bottom. Retractor for seat belts as described. the moving member is pressed against the reaction force surface when the engaging tooth bites into the moving member;
The seat belt retractor according to any one of claims 1 to 4, wherein a minimum distance from the reaction force surface to the bottom of the recess in the radial direction of the driving wheel is larger than the thickness of the moving member. The at least one concave portion formed in at least one engaging tooth among the plurality of engaging teeth has a shape different from the at least one concave portion formed in another engaging tooth. 6. The seat belt retractor according to any one of 5.

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