JP2024101471A - Webbing take-up device - Google Patents

Abstract

To inhibit increase of a drawing allowable load of webbing.SOLUTION: In a webbing take-up device 10, a torsion shaft 20 is deformed in a twisting manner by a load from webbing 16 to allow rotation of a spool 14 in a drawing direction and thereby allow drawing of the webbing 16 from the spool 14. When the torsion shaft 20 is deformed in the twisting manner, a slide object of a rotary surface 14B of the spool 14 is changed from a rib 24B of a pinion 24 to a bearing 26 to reduce slide resistance of the spool 14. Thus, increase of a drawing allowable load of the webbing 16 can be inhibited.SELECTED DRAWING: Figure 1

Description

The present invention relates to a webbing take-up device in which the spool is allowed to rotate in the pull-out direction.

In the belt retractor described in Patent Document 1 below, the webbing is wound around the belt reel, and when the rotation of the belt reel in the pull-out direction is restricted, the load from the webbing causes the torsion rod to twist and deform, allowing the belt reel to rotate in the pull-out direction, and allowing the webbing to be pulled out from the belt reel.

In this type of belt retractor, as the amount of torsional deformation of the torsion rod increases, the load required for torsional deformation of the torsion rod gradually increases, and the allowable pull-out load of the webbing gradually increases.

JP 2022-80305 A

In consideration of the above, the present invention aims to provide a webbing take-up device that can suppress an increase in the allowable pull-out load of the webbing.

The webbing take-up device of the first aspect of the present invention includes a spool around which the webbing worn by an occupant is wound and which rotates in the pull-out direction to pull out the webbing, and which is restricted in its rotation in the pull-out direction in the event of a vehicle emergency; a torsion member which, when the rotation of the spool in the pull-out direction is restricted, is torsionally deformed by the load from the webbing, thereby allowing the spool to rotate in the pull-out direction and allow the webbing to be pulled out from the spool; and a reduction mechanism which reduces the sliding resistance of the spool while the torsion member is torsionally deformed.

The webbing take-up device of the second aspect of the present invention is the webbing take-up device of the first aspect of the present invention, in which at least one of the sliding part of the spool and the part against which the spool slides is changed.

The webbing take-up device of the third aspect of the present invention is the webbing take-up device of the second aspect of the present invention, in which at least one of the sliding part and the slidable part is cut to change at least one of the sliding part and the slidable part.

The webbing take-up device of the fourth aspect of the present invention is the webbing take-up device of the second or third aspect of the present invention, which is provided with a modification member that modifies at least one of the sliding part and the slidable part to become the sliding part or the slidable part.

The webbing take-up device of the fifth aspect of the present invention is a webbing take-up device of any one of the second to fourth aspects of the present invention, in which at least one of the sliding part and the slidable part is changed multiple times.

The webbing take-up device of the sixth aspect of the present invention is a webbing take-up device of any one of the first to fifth aspects of the present invention, further comprising a lubricant that reduces the sliding resistance of the spool.

The webbing take-up device of the seventh aspect of the present invention is a webbing take-up device of any one of the first to sixth aspects of the present invention, in which the maximum volume material of the sliding part of the spool and the part against which the spool slides are made the same.

In the webbing take-up device of the first aspect of the present invention, the webbing to be worn by the occupant is wound around a spool, and the spool is rotated in the pull-out direction to pull out the webbing from the spool. Furthermore, when the rotation of the spool in the pull-out direction is restricted in the event of a vehicle emergency, the torsion member is twisted and deformed by the load from the webbing, allowing the spool to rotate in the pull-out direction and allowing the webbing to be pulled out from the spool.

Here, while the torsion member is being twisted and deformed, the reduction mechanism reduces the sliding resistance of the spool. This makes it possible to suppress an increase in the allowable pull-out load of the webbing.

In the webbing take-up device of the second aspect of the present invention, at least one of the sliding part of the spool and the part against which the spool slides is changed. This allows the sliding resistance of the spool to be changed.

In the webbing take-up device of the third aspect of the present invention, at least one of the sliding part and the slidable part is cut, and at least one of the sliding part and the slidable part is changed. Therefore, at least one of the sliding part and the slidable part can be changed with a simple configuration.

In the webbing take-up device of the fourth aspect of the present invention, at least one of the sliding part and the slidable part is changed, and the change member becomes the sliding part or the slidable part. This makes it easy to change the sliding resistance of the spool.

In the webbing take-up device of the fifth aspect of the present invention, at least one of the sliding part and the slidable part is changed multiple times. This allows the sliding resistance of the spool to be changed multiple times.

In the webbing take-up device of the sixth aspect of the present invention, the lubricant reduces the sliding resistance of the spool. This makes it possible to reduce the sliding resistance of the spool with a simple configuration.

In the webbing take-up device of the seventh aspect of the present invention, the maximum volume material of the sliding part of the spool and the part against which the spool slides are made the same. Therefore, the sliding resistance of the spool can be increased by the sliding part and the part against which the spool slides being burned.

1 is a cross-sectional view showing a webbing take-up device according to an embodiment of the present invention, as viewed from the rear. 1 is a perspective view showing a main part of a webbing take-up device according to an embodiment of the present invention, viewed obliquely from below and to the right. FIG. 2 is a left side perspective view showing a bearing of the webbing take-up device according to the embodiment of the present invention. 1A is a cross-sectional view from the left side showing a main part of a webbing take-up device according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view from the left side showing a main part of a webbing take-up device according to a modified embodiment of the present invention. 4 is a graph showing a relationship between a webbing withdrawal stroke (horizontal axis) and a webbing allowable withdrawal load (vertical axis) in the webbing take-up device according to the embodiment of the present invention.

Figure 1 shows a cross-sectional view of a webbing take-up device 10 according to an embodiment of the present invention as seen from the rear, and Figure 2 shows a perspective view of the main parts of the webbing take-up device 10 as seen from the lower right. In the drawings, the front of the webbing take-up device 10 is indicated by an arrow FR, the right of the webbing take-up device 10 is indicated by an arrow RH, and the top of the webbing take-up device 10 is indicated by an arrow UP.

The webbing take-up device 10 according to this embodiment is installed in a vehicle, and the front, left, and top of the webbing take-up device 10 are oriented, for example, outward in the vehicle width direction, and toward the front and top of the vehicle, respectively.

As shown in Figures 1 and 2, the webbing retractor 10 has a metal frame 12 with a U-shaped cross section as a support body, and the frame 12 has a rear back plate 12A, a left leg plate 12B, and a right leg plate 12C. The frame 12 is fixed to the vehicle body at the back plate 12A, and the webbing retractor 10 is installed on the vehicle. The leg plate 12B and the leg plate 12C have circular support holes 12D and 12E formed therethrough, respectively, and the support holes 12D and 12E are arranged coaxially.

Between the leg plates 12B and 12C of the frame 12, a roughly cylindrical spool 14 is disposed as a rotating body, and the spool 14 is made of aluminum die casting. The left end of the spool 14 is coaxially inserted through the support hole 12D of the leg plate 12B, and the right end of the spool 14 is coaxially inserted through the support hole 12E of the leg plate 12C, and the spool 14 is supported so that it can rotate in the winding direction and the pull-out direction around the central axis.

A roughly cylindrical inner hole 14A is formed coaxially through the spool 14. The left end of the inner hole 14A is enlarged coaxially, and the circumferential surface of the left end of the inner hole 14A is a cylindrical rotating surface 14B (see FIG. 4A) that serves as a sliding portion.

A long strip-shaped webbing 16 is wound around the spool 14 from the base end. When the spool 14 is rotated in the winding direction, the webbing 16 is wound around the spool 14, and the webbing 16 is pulled out from the spool 14 and rotated in the pulling out direction. When the webbing 16 is pulled out from the spool 14, the webbing 16 is attached to a passenger seated in a vehicle seat.

A biasing mechanism 18 is provided on the right side of the frame 12, and is connected to the right end of the spool 14 to bias the spool 14 in the winding direction.

A roughly cylindrical torsion shaft 20 serving as a torsion member (energy absorbing member) is coaxially inserted into the inner hole 14A of the spool 14, and the torsion shaft 20 is made of soft iron. The right end of the torsion shaft 20 is connected to the right end of the inner hole 14A of the spool 14 so as to be able to rotate together with the spool 14, and the torsion shaft 20 is able to rotate together with the spool 14. The left end of the torsion shaft 20 is disposed within the rotation surface 14B of the inner hole 14A.

A locking mechanism 22 is provided on the left side of the spool 14 as a restricting mechanism.

The locking mechanism 22 is provided with a generally disk-shaped pinion 24 as a connecting member that constitutes a regulating body, and the pinion 24 is made of aluminum die-casting. Therefore, the material of the pinion 24 and the material of the spool 14 are made of the same type of metal, and the maximum volume material of the pinion 24 and the spool 14 is made of the same metal.

A roughly cylindrical connecting tube 24A (see FIG. 4A) is coaxially and integrally formed on the right side of the pinion 24 as a connecting part, and the outer circumferential surface of the connecting tube 24A is cylindrical and is coaxially inserted into the rotating surface 14B of the spool 14 (inner bore 14A). The left end of the torsion shaft 20 is connected to the connecting tube 24A so as to be rotatable therewith, and the pinion 24 is rotatable therewith.

A predetermined number (eight in this embodiment) of semi-cylindrical ribs 24B are integrally formed on the outer circumferential surface of the connecting tube 24A as sliding parts that constitute the lowering mechanism, and the ribs 24B protrude radially outward from the connecting tube 24A and extend in the axial direction of the connecting tube 24A. The predetermined number of ribs 24B are arranged at equal intervals around the circumference of the connecting tube 24A, and the connecting tube 24A is in contact with the rotating surface 14B of the spool 14 (inner hole 14A) at the predetermined number of ribs 24B.

A roughly cylindrical bearing 26 (see Figs. 3 and 4A) as a change member and a sliding part constituting the lowering mechanism is arranged coaxially on the outer periphery of the connecting tube 24A, and the bearing 26 is made of resin. A predetermined number (eight in this embodiment) of long rectangular through holes 26A are formed through the bearing 26, and the predetermined number of through holes 26A each extend in the axial direction of the bearing 26 and are arranged at equal intervals in the circumferential direction of the bearing 26. A rib 24B of the connecting tube 24A penetrates the through hole 26A, and the inner peripheral surface of the bearing 26 is fitted (contacted) with the outer peripheral surface of the connecting tube 24A. The rib 24B protrudes radially outward from the bearing 26, and the outer peripheral surface of the bearing 26 is spaced apart from the rotating surface 14B of the spool 14 (inner hole 14A).

A roughly disk-shaped metal lock base 28 is arranged coaxially to the left of the pinion 24 as a regulating member constituting the regulating body, and the lock base 28 is connected to the pinion 24 so as to be rotatable together with it.

The lock mechanism 22 is provided with a sensor mechanism 30 on the left side of the lock base 28. In the event of a vehicle collision (in the event of a vehicle emergency, such as sudden vehicle deceleration or sudden withdrawal of the webbing 16 from the spool 14), the sensor mechanism 30 is activated and the lock mechanism 22 restricts (locks) the rotation of the lock base 28 in the withdrawal direction, thereby restricting the rotation of the pinion 24 in the withdrawal direction and limiting the rotation of the spool 14 in the withdrawal direction via the torsion shaft 20.

Next, the operation of this embodiment will be explained.

In the webbing take-up device 10 configured as described above, the webbing 16 is pulled out from the spool 14 and placed on the occupant. In addition, the spool 14 is rotated in the take-up direction by the biasing force of the biasing mechanism 18, and the webbing 16 is taken up onto the spool 14, thereby removing slack in the webbing 16 placed on the occupant.

When the vehicle crashes, the sensor mechanism 30 of the lock mechanism 22 is activated, and the lock mechanism 22 restricts the rotation of the lock base 28 in the pull-out direction, restricting the rotation of the pinion 24 in the pull-out direction and restricting the rotation of the spool 14 in the pull-out direction via the torsion shaft 20. This restricts the pull-out of the webbing 16 from the spool 14, and the occupant is restrained by the webbing 16.

In addition, with the rotation of the lock base 28 and pinion 24 in the pull-out direction restricted, the occupant applies a pulling load from the spool 14 to the webbing 16, and the rotational load in the pull-out direction of the spool 14 causes the torsion shaft 20 to twist. This allows the spool 14 to rotate in the pull-out direction relative to the lock base 28 and pinion 24, allowing the webbing 16 to be pulled out from the spool 14. As a result, the kinetic energy of the occupant is absorbed by the torsional deformation of the torsion shaft 20.

When the torsion shaft 20 is twisted (plastically deformed), the load for twisting the torsion shaft 20 (torsion deformation load of the torsion shaft 20) gradually increases in proportion to the increase in the amount of twisting deformation of the torsion shaft 20 (see the dashed line in FIG. 5). Also, when the webbing 16 is allowed to be pulled out (when the spool 14 is allowed to rotate in the pull-out direction), the load for pulling out the webbing 16 (allowable pull-out load of the webbing 16, force limiter load) becomes the sum of the twisting deformation load of the torsion shaft 20 and the sliding load of the spool 14.

In the initial stage of torsional deformation of the torsion shaft 20 (when the webbing 16 is allowed to be pulled out), the rotating surface 14B of the spool 14 (inner hole 14A) slides against the rib 24B of the pinion 24 (connecting tube 24A). The material of the spool 14 (rotating surface 14B) and the material of the pinion 24 (rib 24B) are made of the same type of metal. Therefore, when the rotating surface 14B slides against the rib 24B, the rotating surface 14B and the rib 24B are seized, increasing the sliding load of the rotating surface 14B against the rib 24B, and increasing the sliding load of the spool 14.

As a result, even if the torsional deformation load of the torsion shaft 20 is small at the beginning of the torsional deformation of the torsion shaft 20, the sliding load of the spool 14 is increased, so that the allowable pull-out load of the webbing 16 is increased (see the solid line in Figure 5).

In addition, when the rotating surface 14B slides against the rib 24B, the rib 24B is gradually scraped by the rotating surface 14B in the pinion 24 (connecting tube 24A), and the amount of protrusion of the rib 24B against the bearing 26 is gradually reduced. Therefore, when the torsion shaft 20 is torsionally deformed, the state in which the rotating surface 14B slides against the rib 24B is gradually changed to the state in which the rotating surface 14B slides against the bearing 26. As a result, in the middle period of the torsion shaft 20 being torsionally deformed, the rotating surface 14B slides against the rib 24B and the bearing 26, and in the later period of the torsion shaft 20 being torsionally deformed, the rotating surface 14B slides against the bearing 26. In addition, the spool 14 (rotating surface 14B) is made of metal, and the bearing 26 is made of resin. Therefore, when the rotating surface 14B slides against the bearing 26, the sliding load of the rotating surface 14B against the bearing 26 is reduced (to approximately zero).

As a result, in the middle period of the torsional deformation of the torsion shaft 20, the torsional deformation load of the torsion shaft 20 is gradually increased, while the sliding load of the rotating surface 14B against the rib 24B is gradually decreased, and the sliding load of the rotating surface 14B against the bearing 26 is decreased (to approximately zero), and the sliding load of the spool 14 is gradually decreased, thereby maintaining the allowable pull-out load of the webbing 16 (see solid line in Figure 5).

Then, in the later stage of the torsion shaft 20 being torsionally deformed, the torsion deformation load of the torsion shaft 20 is gradually increased, while the sliding load of the rotating surface 14B against the bearing 26 is reduced (to approximately zero), and the sliding load of the spool 14 is reduced (to approximately zero), so that the allowable pull-out load of the webbing 16 is gradually increased (see the solid line in Figure 5).

As a result, when the torsion shaft 20 is torsionally deformed, the allowable pull-out load of the webbing 16 is averaged relative to the amount of torsion deformation of the torsion shaft 20.

As described above, in the middle and later stages of torsional deformation of the torsion shaft 20, the sliding target of the rotating surface 14B of the spool 14 is changed from the rib 24B of the pinion 24 to the bearing 26, and the sliding resistance of the spool 14 is reduced. This makes it possible to suppress an increase in the allowable pull-out load of the webbing 16.

In addition, when the torsion shaft 20 is torsionally deformed, the rib 24B is scraped by the rotating surface 14B, and the sliding object of the rotating surface 14B is changed from the rib 24B to the bearing 26. Therefore, the sliding object of the rotating surface 14B can be changed with a simple structure.

Furthermore, when the torsion shaft 20 is torsionally deformed, the sliding object of the rotating surface 14B is changed from the rib 24B of the pinion 24 to the bearing 26, which is a separate member from the pinion 24. This makes it easy to reduce the sliding resistance of the spool 14.

The spool 14 (rotation surface 14B) and the pinion 24 (rib 24B) are made of the same metal, and when the torsion shaft 20 is initially twisted, the rotation surface 14B slides against the rib 24B, causing the rotation surface 14B and the rib 24B to seize. This increases the sliding resistance of the spool 14, and even if the torsional deformation load of the torsion shaft 20 is small, the allowable pull-out load of the webbing 16 can be increased, thereby increasing the restraining force of the occupant by the webbing 16.

(Modification)
FIG. 4B shows a cross-sectional view of a main portion of a webbing take-up device 50 according to a modified example of the above embodiment, as viewed from the left side.

As shown in FIG. 4(B), in the webbing take-up device 50 according to this modified example, the ribs 24B of the pinion 24 (connecting tube 24A) are rectangular plate-shaped, and the ribs 24B are curved along the circumferential direction of the connecting tube 24A. A predetermined number of ribs 24B (six in this modified example) are provided, and the predetermined number of ribs 24B are arranged at equal intervals along the circumferential direction of the connecting tube 24A.

The bearing 26 is provided with a predetermined number of through holes 26A (six in this modified example), and the predetermined number of through holes 26A are arranged at equal intervals in the circumferential direction of the bearing 26. The dimension of the through holes 26A in the circumferential direction of the bearing 26 is larger than in the above embodiment, and the rib 24B of the pinion 24 (connecting tube 24A) passes through the through holes 26A.

Here, this modified example can achieve the same effects and advantages as the above embodiment.

Furthermore, as in this modified example, by changing at least one of the shape, size, and number of the ribs 24B and the through holes 26A from the above embodiment, the magnitude of the sliding load of the spool 14 and the timing of the reduction in the sliding load of the spool 14 can be adjusted.

In the above embodiment (including the modified example), the spool 14 (sliding member) and the pinion 24 (sliding member) are made of aluminum die-casting. However, the spool 14 (sliding member) and the pinion 24 (sliding member) may be made of zinc die-casting, for example. Moreover, the material of the spool 14 (sliding member) and the material of the pinion 24 (sliding member) do not have to be completely the same metal, and the spool 14 and the pinion 24 only need to be metals with the same maximum volume material. Furthermore, the material of the spool 14 (sliding member) and the material of the pinion 24 (sliding member) may be different materials.

In addition, in the above embodiment (including the modified example), the bearing 26 is made of resin. However, the material of the bearing 26 may be any material other than the maximum volume material of the spool 14 and the pinion 24 (e.g., iron).

Furthermore, in the above embodiment (including the modified example), the bearing 26 is disposed on the outer circumferential surface of the connecting tube 24A of the pinion 24. However, instead of the bearing 26, a lowering mechanism and grease as a lubricant may be disposed (applied) on the outer circumferential surface of the connecting tube 24A of the pinion 24. In this case, grease is disposed instead in the range where the bearing 26 is disposed. As a result, when the torsion shaft 20 is torsionally deformed, the rib 24B of the connecting tube 24A is gradually scraped by the rotating surface 14B of the spool 14, and the state in which the rotating surface 14B slides against the rib 24B is changed to a state in which the rotating surface 14B slides against the rib 24B via the grease, thereby reducing the sliding resistance of the spool 14.

In the above embodiment (including the modified example), the protruding amount of the ribs 24B of the pinion 24 (connecting tube 24A) is the same. However, the protruding amount of the ribs 24B of the pinion 24 (connecting tube 24A) may differ from one another. In this case, when the torsion shaft 20 is torsionally deformed, the rotating surface 14B of the spool 14 sequentially cuts the ribs 24B with the maximum protruding amount to the ribs 24B with the minimum protruding amount, increasing the number of ribs 24B against which the rotating surface 14B slides, and gradually increasing the sliding resistance of the spool 14. After that, the rotating surface 14B is changed from a state in which it slides against the ribs 24B to a state in which it slides against the bearings 26 (it may slide against the ribs 24B via grease).

Furthermore, in the above embodiment (including the modified example), the connecting tube 24A of the pinion 24 is provided with the rib 24B and the bearing 26 (which may be grease). However, the rotating surface 14B of the spool 14 may be provided with the rib 24B and the bearing 26 (which may be grease). In this case, when the torsion shaft 20 is torsionally deformed, the state in which the rib 24B (sliding part) slides against the outer circumferential surface (sliding part) of the connecting tube 24A is changed to a state in which the bearing 26 (sliding part) slides against the outer circumferential surface of the connecting tube 24A (the rib 24B may slide against the outer circumferential surface of the connecting tube 24A via grease).

In addition, in the above embodiment (including the modified example), a rib 24B and a bearing 26 (which may be grease) are provided between the spool 14 and the pinion 24, and the spool 14 slides against the pinion 24 when the torsion shaft 20 is torsionally deformed. However, a rib 24B and a bearing 26 (which may be grease) may be provided between the spool 14 and a portion other than the pinion 24 (for example, the left portion of the torsion shaft 20), and the spool 14 may slide against the portion other than the pinion 24 when the torsion shaft 20 is torsionally deformed.

Furthermore, in the above embodiment (including the modified example), when the torsion shaft 20 is torsionally deformed, the sliding resistance of the spool 14 is reduced to approximately zero. However, when the torsion shaft 20 is torsionally deformed, the sliding resistance of the spool 14 may be reduced to zero.

In addition, in the above embodiment (including the modified example), when the torsion shaft 20 is torsionally deformed (plastically deformed), the torsion deformation load of the torsion shaft 20 is gradually increased in proportion to the increase in the amount of torsion deformation of the torsion shaft 20. However, when the torsion shaft 20 is torsionally deformed (plastically deformed), the torsion deformation load of the torsion shaft 20 only needs to be increased as the amount of torsion deformation of the torsion shaft 20 increases.

10: Webbing winding device, 14: Spool, 14B: Rotating surface (sliding part), 16: Webbing, 20: Torsion shaft (torsion member), 24B: Rib (lowering mechanism, sliding part), 26: Bearing (lowering mechanism, change member, sliding part), 50: Webbing winding device

Claims (7)

a spool around which a webbing to be worn by an occupant is wound and which is rotated in a pull-out direction to pull out the webbing, and which is restricted in its rotation in the pull-out direction in the event of a vehicle emergency;
a torsion member that is torsionally deformed by a load from the webbing when the rotation of the spool in the unwinding direction is restricted, thereby allowing the rotation of the spool in the unwinding direction and allowing the webbing to be unwound from the spool;
a reduction mechanism that reduces the sliding resistance of the spool while the torsion member is being torsionally deformed;
A webbing take-up device comprising: The webbing take-up device according to claim 1, in which at least one of the sliding part of the spool and the part against which the spool slides is changed. The webbing take-up device according to claim 2, wherein at least one of the sliding part and the slidable part is changed by cutting the sliding part and at least one of the slidable part. The webbing take-up device according to claim 2, further comprising a modification member that modifies at least one of the sliding part and the slidable part to become the sliding part or the slidable part. The webbing take-up device according to claim 2, in which at least one of the sliding part and the slidable part is changed multiple times. The webbing take-up device according to claim 1, further comprising a lubricant that reduces the sliding resistance of the spool. The webbing take-up device according to claim 1, in which the maximum volume of material of the sliding part of the spool and the part against which the spool slides are the same.