Webbing winding device

Abstract

In this webbing winding device, a sub-torsion in a spool is engaged with a stopper base, and when rotation of the stopper base in the pull-out direction is restricted, the sub-torsion is subjected to torsional deformation, thereby allowing rotation of the spool in the pull-out direction with respect to the stopper base. Here, a switching mechanism switches between operation and non-operation of each of a pair of sub-torsions. Therefore, it is possible to increase the number of stages at which the force limiter load can be changed.

Description

Webbing retractor

[0001] The present invention relates to a webbing take-up device in which rotation of a spool in the unwinding direction is permitted when rotation of a regulating gear is regulated.

[0002] In the seat belt retractor disclosed in JP 2015-54647 A, a second torsion bar is disposed within the spool and is engaged with a first gear, and when rotation of the first gear is restricted, the second torsion bar is torsionally deformed, allowing rotation of the spool in the pull-out direction. In addition, a release ring switches between operating and inoperating the second torsion bar.

[0003] In this seat belt retractor, it is preferable that the force limiter load (the load that allows the seat belt to be withdrawn from the spool) can be changed in many stages, and it is also preferable that the second torsion bar can be twisted satisfactorily.

[0004] In consideration of the above, an object of the present invention is to provide a webbing take-up device that can increase the number of stages in which the force limiter load can be changed and a webbing take-up device that can favorably torsionally deform a deformation member.

[0005] A webbing take-up device of a first aspect of the present invention includes a spool around which a webbing to be worn by an occupant is wound and from which the webbing is pulled out and rotated in the pull-out direction; a regulating gear that can regulate rotation; a plurality of deformable members that are disposed within the spool and engaged with the regulating gear, and that are torsionally deformed when rotation of the regulating gear is regulated, thereby allowing rotation of the spool in the pull-out direction; and a switching mechanism that switches between operating and non-operating states of each of the plurality of deformable members.

[0006] A webbing take-up device of a second aspect of the present invention is the webbing take-up device of the first aspect of the present invention, wherein the switching mechanism switches between operating and non-operating states of the deformable member before or when the deformable member is torsionally deformed.

[0007] A webbing take-up device of a third aspect of the present invention is the webbing take-up device of the first or second aspect of the present invention, wherein the switching mechanism is disposed on the opposite side of the spool from the regulating gear.

[0008] A webbing take-up device of a fourth aspect of the present invention includes a spool around which a webbing to be worn by an occupant is wound, and around which the webbing is pulled out and rotated in the pull-out direction; a regulating gear that is capable of restricting rotation; and a plurality of deformable members that are disposed within the spool, engage with the regulating gear, have strength lower than that of the regulating gear, and are torsionally deformed when rotation of the regulating gear is restricted, thereby allowing rotation of the spool in the pull-out direction.

[0009] A webbing take-up device of a fifth aspect of the present invention is the webbing take-up device of any one of the first to fourth aspects of the present invention, further comprising a gear portion that is provided on the deformable member, meshes with the regulating gear, and has strength that is greater than the strength of the deformable member.

[0010] A webbing take-up device of a sixth aspect of the present invention is the webbing take-up device of any one of the first to fifth aspects of the present invention, wherein the restriction gear is engaged with the deformable member on the inner side in the rotational radial direction.

[0011] A webbing take-up device according to a seventh aspect of the present invention is the webbing take-up device according to the sixth aspect of the present invention, wherein the restricting gear is engaged with the plurality of deformable members on an inner side in the rotational radial direction.

[0012] In the webbing take-up device of the first aspect of the present invention, a webbing to be worn by an occupant is wound around a spool, and as the webbing is pulled out from the spool, the spool is rotated in the pull-out direction. Furthermore, a plurality of deformable members are disposed within the spool and are engaged with a restricting gear, and when rotation of the restricting gear is restricted, the deformable members are torsionally deformed, thereby allowing rotation of the spool in the pull-out direction.

[0013] Here, the switching mechanism switches between operating and non-operating states of each of the multiple deformation members, thereby increasing the number of stages over which the force limiter load (the load that allows the webbing to be pulled out from the spool) can be changed.

[0014] In the webbing take-up device of the second aspect of the present invention, the switching mechanism switches between operating and inoperating the deformable member before or when the deformable member is torsionally deformed, thereby making it possible to adjust fluctuations in the force limiter load.

[0015] In the webbing take-up device of the third aspect of the present invention, the switching mechanism is disposed on the opposite side of the spool from the regulating gear, which makes it easy to arrange the switching mechanism.

[0016] In the webbing take-up device of the fourth aspect of the present invention, a webbing to be worn by an occupant is wound around a spool, and as the webbing is pulled out from the spool, the spool is rotated in the pull-out direction. Furthermore, a plurality of deformable members are disposed within the spool and are engaged with a restricting gear, and when rotation of the restricting gear is restricted, the deformable members are torsionally deformed, thereby allowing rotation of the spool in the pull-out direction.

[0017] Here, the strength of the deformable member is set lower than the strength of the regulating gear, so that deformation of the regulating gear can be suppressed and the deformable member can be twisted and deformed satisfactorily.

[0018] In the webbing take-up device of the fifth aspect of the present invention, the gear portion of the deformable member is meshed with the restricting gear.

[0019] Here, the strength of the gear portion is made higher than the strength of the deformable member, so that deformation of the gear portion can be suppressed and the deformable member can be twisted and deformed well.

[0020] In the webbing take-up device of the sixth aspect of the present invention, the restricting gear is engaged with the deformable member on the inner side in the rotational diameter direction, so that the deformable member can be disposed on the inner side in the rotational diameter direction of the restricting gear.

[0021] In the webbing take-up device of the seventh aspect of the present invention, the restricting gear is engaged with the plurality of deformable members on the inner side in the rotational diameter direction, so that the plurality of deformable members can be disposed close to each other on the inner side in the rotational diameter direction of the restricting gear.

[0022] 1 is a cross-sectional view (cross-sectional view taken along line 1-1 in FIG. 2) showing the webbing take-up device according to the first embodiment of the present invention as viewed from the front. FIG. 2 is a right-side view showing a spool and the like of the webbing take-up device according to the first embodiment of the present invention as viewed from the right. FIG. 3 is a cross-sectional view (cross-sectional view taken along line 1-1 in FIG. 2) showing the webbing take-up device according to the first embodiment of the present invention when the force limiter load is set to a high load. FIG. 4 is a graph showing the relationship between the webbing pull-out stroke (chest movement amount S, horizontal axis) and the force limiter load (shoulder load F, vertical axis) when the force limiter load of the webbing take-up device according to the first embodiment of the present invention is set to a high load. FIG. 5 is a cross-sectional view (cross-sectional view taken from the front) showing the relationship between the webbing pull-out stroke (chest movement amount S, horizontal axis) and the force limiter load (shoulder load F, vertical axis) when the force limiter load of the webbing take-up device according to the first embodiment of the present invention is set to a medium load. FIG. 6 is a cross-sectional view (cross-sectional view taken from the front) showing the relationship between the webbing pull-out stroke (chest movement amount S, horizontal axis) and the force limiter load (shoulder load F, vertical axis) when the force limiter load of the webbing take-up device according to the first embodiment of the present invention is set to a medium load. 1 is a graph showing the relationship between the webbing pull-out stroke (chest movement amount S, horizontal axis) and the force limiter load (shoulder load F, vertical axis) when the force limiter load of the webbing take-up device according to the first embodiment of the present invention is set to a low load. FIG. 2 is a cross-sectional view, seen from the front, of the webbing take-up device according to a second embodiment of the present invention. FIG. 3 is a cross-sectional view, seen from the front, of the webbing take-up device according to the second embodiment of the present invention when the force limiter load is set to a high load. FIG. 4 is a graph showing the relationship between the webbing pull-out stroke (chest movement amount S, horizontal axis) and the force limiter load (shoulder load F, vertical axis) when the force limiter load of the webbing take-up device according to the second embodiment of the present invention is set to a high load. FIG. 5 is a cross-sectional view, seen from the front, of the webbing take-up device according to the second embodiment of the present invention when the force limiter load is set to a medium load. FIG. 6 is a graph showing the relationship between the webbing pull-out stroke (chest movement amount S, horizontal axis) and the force limiter load (shoulder load F, vertical axis) when the force limiter load of the webbing take-up device according to the second embodiment of the present invention is set to a medium load.10 is a graph showing the relationship between a webbing pull-out stroke (chest movement amount S, horizontal axis) and a force limiter load (shoulder load F, vertical axis) when the force limiter load of a webbing take-up device according to a second embodiment of the present invention is set to a low load. FIG. 11 is a perspective view of a webbing take-up device according to a second embodiment of the present invention, seen from diagonally above right. FIG. 12 is a perspective view of a webbing take-up device according to a second embodiment of the present invention, seen from diagonally above left. FIG. 13 is a front view of a webbing take-up device according to a second embodiment of the present invention, seen from the front. FIG. 14 is a top view of a webbing take-up device according to a second embodiment of the present invention, seen from above. FIG. 15 is a left side view of a webbing take-up device according to a second embodiment of the present invention, seen from the left. FIG. 16 is an exploded perspective view of a webbing take-up device according to a second embodiment of the present invention, seen from diagonally above right. FIG. 17 is an exploded perspective view of a webbing take-up device according to a second embodiment of the present invention, seen from diagonally above left. FIG. 18 is a top view of a webbing take-up device according to a second embodiment of the present invention, seen from above. FIG. 19 is a right side view of a spool and the like of a webbing take-up device according to a second embodiment of the present invention, seen from the right. FIG. 19 is a front view of a main part of a webbing take-up device according to a second embodiment of the present invention, seen from the front. 1 is a top view showing a main part of a webbing take-up device according to a second embodiment of the present invention, as viewed from above. FIG. 2 is a right side view showing a main part of a webbing take-up device according to the second embodiment of the present invention, as viewed from the right. FIG. 3 is a left side view showing a main part of a webbing take-up device according to the second embodiment of the present invention, as viewed from the left. FIG. 4 is an exploded perspective view showing a spool and the like of a webbing take-up device according to the second embodiment of the present invention, as viewed from the right. FIG. 5 is an exploded perspective view showing a spool and the like of a webbing take-up device according to the second embodiment of the present invention, as viewed from the left. FIG. 6 is a cross-sectional view showing a first position of the spool and the like of a webbing take-up device according to the second embodiment of the present invention, as viewed from the left. FIG. 7 is a cross-sectional view showing a second position of the spool and the like of a webbing take-up device according to the second embodiment of the present invention, as viewed from the left. FIG. 8 is a front view showing a webbing take-up device according to a third embodiment of the present invention, as viewed from the front. FIG. 9 is a right side view showing a spool and the like of a webbing take-up device according to the third embodiment of the present invention, as viewed from the right. FIG. 10 is an exploded perspective view showing a spool and the like of a webbing take-up device according to the third embodiment of the present invention, as viewed from the left.10 is a graph showing the relationship between the webbing pull-out stroke (chest movement amount S, horizontal axis) and the force limiter load (shoulder load F, vertical axis) when the force limiter load of the webbing take-up device according to the third embodiment of the present invention is set to a high load. FIG. 11 is a graph showing the relationship between the webbing pull-out stroke (chest movement amount S, horizontal axis) and the force limiter load (shoulder load F, vertical axis) when the force limiter load of the webbing take-up device according to the third embodiment of the present invention is set to a medium load. FIG. 12 is a graph showing the relationship between the webbing pull-out stroke (chest movement amount S, horizontal axis) and the force limiter load (shoulder load F, vertical axis) when the force limiter load of the webbing take-up device according to the third embodiment of the present invention is set to a low load. FIG. 13 is a graph showing the relationship between the webbing pull-out stroke (chest movement amount S, horizontal axis) and the force limiter load (shoulder load F, vertical axis) when the force limiter load of the webbing take-up device according to the third embodiment of the present invention is set to a medium load from a high load. 10 is a graph showing the relationship between the webbing pull-out stroke (chest movement amount S, horizontal axis) and the force limiter load (shoulder load F, vertical axis) when the force limiter load of the webbing take-up device according to the third embodiment of the present invention is changed from a high load to a medium load and then to a low load. FIG. 11 is a graph showing the relationship between the webbing pull-out stroke (chest movement amount S, horizontal axis) and the force limiter load (shoulder load F, vertical axis) when the force limiter load of the webbing take-up device according to the third embodiment of the present invention is changed from a high load to a low load. FIG. 12 is a graph showing the relationship between the webbing pull-out stroke (chest movement amount S, horizontal axis) and the force limiter load (shoulder load F, vertical axis) when the force limiter load of the webbing take-up device according to the third embodiment of the present invention is changed from a medium load to a low load.

[0023] 1 shows a cross-sectional view of a webbing take-up device 10 according to a first embodiment of the present invention as viewed from the front. In the drawing, 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.

[0024] The webbing take-up device 10 according to this embodiment is installed in a vehicle, and the front, right and upper sides of the webbing take-up device 10 are oriented, for example, outward in the vehicle width direction, and toward the front and upper sides of the vehicle, respectively.

[0025] 1, the webbing retractor 10 is provided with a frame 12 (see FIGS. 9A and 9B) having a U-shaped cross section and serving as a support body, and the frame 12 is provided with 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, thereby installing the webbing retractor 10 on the vehicle.

[0026] A box-shaped cover plate 14 serving as a restricting member is fixed to the right side of the frame 12 (leg plate 12C), and the interior of the cover plate 14 is open to the left and closed from the left side by the leg plate 12B. A ratchet hole 14A is formed through the right wall of the cover plate 14, and ratchet teeth 14B serving as a restricting portion are formed around the entire periphery of the ratchet hole 14A.

[0027] A substantially cylindrical spool 16 is rotatably supported between the leg plates 12B and 12C of the frame 12, with the left and right ends of the spool 16 penetrating the leg plates 12B and 12C, respectively. A substantially cylindrical arrangement hole 16A is coaxially formed in the right portion of the spool 16 and opens to the right side. A plurality of (three in this embodiment) substantially cylindrical insertion holes 16B (see FIG. 2 ) are formed around the periphery of the spool 16, and the insertion holes 16B are equally spaced around the periphery of the spool 16. The insertion holes 16B extend in the axial direction (left-right direction) of the spool 16 and open to the left side of the spool 16 and the arrangement hole 16A.

[0028] A long, strip-shaped webbing 18 is wound around the spool 16 from the base end in the longitudinal direction. When the spool 16 is rotated in the winding direction, the webbing 18 is wound onto the spool 16, and when the webbing 18 is pulled out from the spool 16, the spool 16 is rotated in the unwinding direction. When the webbing 18 is pulled out from the spool 16, the webbing 18 is worn by an occupant seated in a vehicle seat (not shown). When the webbing 18 is worn by the occupant, the webbing 18 is wrapped diagonally from one shoulder (left or right) of the occupant across the chest to the other side (right or left) of the occupant's waist, and also wrapped laterally between one side and the other side of the occupant's waist. A body size sensor (e.g., a weight sensor) is provided in the seat, and the body size sensor detects the body size of the occupant seated in the seat.

[0029] A soft iron, substantially cylindrical main torsion 20 (main torsion shaft, see FIG. 2 ) serving as a first deformation member (first energy absorption member) is coaxially inserted into one insertion hole 16B of the spool 16, with the left end of the main torsion 20 non-rotatably connected to the spool 16 and the right end of the main torsion 20 disposed in the arrangement hole 16A of the spool 16. A cylindrical main gear 20A made of iron serving as a gear portion is coaxially connected to the right end of the main torsion 20, and the main gear 20A rotates integrally with the right end of the main torsion 20.

[0030] A soft iron, substantially cylindrical sub-torsion member 22 (sub-torsion shaft, see FIG. 2 ) serving as a second deformation member (second energy absorption member) is coaxially inserted into the two insertion holes 16B of the spool 16. The left end of the sub-torsion member 22 is non-rotatably connected to the spool 16, and the right end of the sub-torsion member 22 is disposed in the arrangement hole 16A of the spool 16. A cylindrical iron sub-gear 22A serving as a gear member is coaxially connected to the right end of the sub-torsion member 22, and the sub-gear 22A rotates integrally with the right end of the sub-torsion member 22. The pair of sub-torsion members 22 have the same torsional load resistance, which is smaller than the torsional load resistance of the main torsion member 20. The sub-torsion member 22 is also movable leftward.

[0031] A substantially bottomed cylindrical stopper tube 24 is coaxially fitted into the arrangement hole 16A of the spool 16 to the right of the main torsion 20 and sub torsion 22. The stopper tube 24 rotates integrally with the spool 16 and has an interior that is open to the right. Three cylindrical support shafts 24A are integrally provided on the left surface of the stopper tube 24, and the support shafts 24A protrude to the left. One support shaft 24A is coaxially fitted into the right end of the main torsion 20 to rotatably support the right end of the main torsion 20, and the two support shafts 24A are each coaxially fitted into the right end of the sub torsion 22 to rotatably support the right end of the main torsion 20. The interior of the stopper tube 24 is non-circular when viewed from the front.

[0032] A substantially disk-shaped iron stopper base 26 serving as a regulating gear is provided coaxially on the right side of the spool 16 .

[0033] A columnar threaded post 26A is integrally and coaxially provided at the center of the stopper base 26, and the threaded post 26A protrudes to the left and is coaxially inserted into the stopper tube 24. The inner periphery of an annular stopper 28 is threadedly engaged with the outer periphery of the threaded post 26A, and the outer periphery of the stopper 28 is non-circular. The outer periphery of the stopper 28 is fitted into the inner periphery of the stopper tube 24, so that the stopper 28 can rotate integrally with the stopper tube 24 and the spool 16. The stopper 28 is located at the left end of the threaded post 26A, and when the spool 16 is rotated in the withdrawal direction relative to the stopper base 26, the stopper 28 rotates integrally with the stopper tube 24 and the spool 16 in the withdrawal direction and moves to the right. When the stopper 28 abuts against the stopper base 26, the rotation of the stopper tube 24 and the spool 16 relative to the stopper base 26 in the pull-out direction is restricted.

[0034] A stopper gear 26B serving as a gear portion is provided integrally and coaxially on the left side of the threaded column 26A, and the stopper gear 26B protrudes to the left and penetrates coaxially through the left wall (bottom wall) of the stopper tube 24. The stopper gear 26B protrudes to the left side of the stopper tube 24, and is meshed with the main gear 20A of the main torsion 20 and the sub gears 22A of the pair of sub torsions 22. The stopper base 26 is connected to the spool 16 via the main torsion 20 and the pair of sub torsions 22, and the stopper base 26 rotates integrally with the spool 16.

[0035] A pinion 30, which is a substantially annular plate-shaped member and serves as a regulated member, is coaxially provided on the right side of the stopper base 26, and the pinion 30 is connected to the stopper base 26 so as to be rotatable integrally with the stopper base 26. The pinion 30 is coaxially inserted through the ratchet hole 14A of the cover plate 14, and a lock plate 30A, which serves as a regulated portion, is rotatably supported by the pinion 30.

[0036] A substantially cylindrical screw shaft 32 is coaxially fitted into the pinion 30, and the right portion of the screw shaft 32 is engaged with the pinion 30 from the right side. The left portion of the screw shaft 32 is coaxially inserted into and screwed into the stopper base 26, whereby the pinion 30 is sandwiched between the right portion of the screw shaft 32 and the stopper base 26.

[0037] A sensor mechanism (not shown) is provided on the right side of the cover plate 14, and the sensor mechanism is connected to the lock plate 30A of the pinion 30. In the event of a vehicle collision (a vehicle emergency such as sudden deceleration of the vehicle or sudden withdrawal of the webbing 18 from the spool 16), the sensor mechanism is activated and the lock plate 30A is rotated radially outward of the pinion 30, whereby the lock plate 30A meshes with the ratchet teeth 14B of the cover plate 14 (ratchet hole 14A), restricting (locking) rotation of the pinion 30 in the withdrawal direction. This restricts rotation of the stopper base 26 in the withdrawal direction, and the main torsion 20 and the pair of sub-torsion members 22 restrict rotation of the spool 16 in the withdrawal direction.

[0038] A switching mechanism 34 is provided on the left side of the frame 12 (leg plate 12B).

[0039] The switching mechanism 34 is provided with a pair of substantially rectangular box-shaped cases 36, which are open to the right side. One case 36 is fixed to the left side of the other case 36, which is fixed to the leg plate 12B.

[0040] A gas generator 38 is fixed to the case 36 and connected to an annular supply pipe 40. The supply pipe 40 is disposed coaxially with the spool 16 within the case 36, and an outlet of the supply pipe 40 is provided around the entire circumference on the left side of the supply pipe 40. A circular switching plate 42 is held coaxially on the left side of the supply pipe 40 and is movable leftward. A disk-shaped moving plate 44 is disposed coaxially on the left side of the switching plate 42 and is movable leftward. The moving plate 44 is connected to the left end of the subtorsion 22 via a substantially cylindrical moving shaft 44A, and the moving shaft 44A of one (left) moving plate 44 penetrates the other (right) moving plate 44. The moving plate 44 and the moving shaft 44A are connected to the spool 16 via the sub-torsion 22, and the moving plate 44 and the moving shaft 44A rotate integrally with the spool 16.

[0041] A generally cylindrical connecting shaft 46 is coaxially connected to the left side of the spool 16, and the connecting shaft 46 rotates integrally with the spool 16. The connecting shaft 46 passes through the pair of cases 36 (including the moving plate 44), and protrudes to the left of the switching mechanism 34. A biasing mechanism (not shown) is provided to the left of the switching mechanism 34, and a power spring is provided within the biasing mechanism as a biasing member. The power spring is connected to the spool 16 via the connecting shaft 46, and the power spring biases the spool 16 in the winding direction.

[0042] Next, the operation of this embodiment will be described.

[0043] In the webbing take-up device 10 configured as described above, the webbing 18 is pulled out from the spool 16 and attached to the occupant. Furthermore, the spool 16 is rotated in the retracting direction by the biasing force of the power spring of the biasing mechanism, and the webbing 18 is retracted onto the spool 16, thereby removing slack from the webbing 18 attached to the occupant.

[0044] In the event of a vehicle collision, the sensor mechanism is activated and the lock plate 30A of the pinion 30 meshes with the ratchet teeth 14B of the cover plate 14 (ratchet hole 14A), restricting rotation of the pinion 30 in the pull-out direction and restricting rotation of the stopper base 26 in the pull-out direction. As a result, the main torsion 20 and the pair of sub-torsion members 22 restrict rotation of the spool 16 in the pull-out direction, restricting pull-out of the webbing 18 from the spool 16, and the occupant is restrained by the webbing 18.

[0045] If the occupant is of large build (if the build sensor detects that the occupant is of large build), the pair of gas generators 38 are not activated in the switching mechanism 34 when a vehicle collision is detected, and the main torsion 20 (main gear 20A) and the pair of sub-torsion 22 (sub-gears 22A) are maintained in mesh with the stopper base 26 (stopper gear 26B) (see Figure 3A). For this reason, when the pulling load from the spool 16 onto the webbing 18 from the occupant (for example, a load acting on the webbing 18 from the occupant's shoulders) is equal to or greater than the force limiter load, which is the total load of the torsional resistance load F1 of the main torsion 20 and the torsional resistance load F2 of the pair of sub-torsion springs 22 (see FIG. 3B ), the main torsion spring 20 and the pair of sub-torsion springs 22 are torsionally deformed, allowing rotation of the spool 16 in the unwinding direction relative to the pinion 30 and the stopper base 26 and allowing the webbing 18 to be unwound from the spool 16. As a result, the force limiter load is increased, and the kinetic energy of the occupant is absorbed by the torsional deformation of the main torsion spring 20 and the pair of sub-torsion springs 22, thereby appropriately protecting a large occupant.

[0046] If the occupant has a medium build (if the build sensor detects that the occupant has a medium build), in the switching mechanism 34, when a vehicle collision is detected, one gas generator 38 is activated to instantaneously generate high-pressure gas in the supply pipe 40, and the pressure of the gas moves one switching plate 42 to the left, and one sub-torsion 22 is moved to the left via one moving plate 44 and moving shaft 44A (see FIG. 4A). As a result, the meshing of one sub-torsion 22 (sub-gear 22A) with the stopper base 26 (stopper gear 26B) is released. For this reason, when the pulling load from the spool 16 onto the webbing 18 from the occupant (for example, a load acting on the webbing 18 from the occupant's shoulder) is equal to or greater than the force limiter load, which is the total load of the torsional resistance load F1 of the main torsion 20 and the torsional resistance load F2 of the other sub-torsion 22 (see FIG. 4B ), the main torsion 20 and the other sub-torsion 22 are torsionally deformed, allowing rotation of the spool 16 in the unwinding direction relative to the pinion 30 and the stopper base 26 and allowing unwinding of the webbing 18 from the spool 16. As a result, the force limiter load is set to a medium load, and the kinetic energy of the occupant is absorbed by the torsional deformation of the main torsion 20 and the other sub-torsion 22, so that the medium-sized occupant is appropriately protected.

[0047] If the occupant is small in stature (if the physique sensor detects that the occupant is small in stature), in the switching mechanism 34, when a vehicle collision is detected, the pair of gas generators 38 are activated to instantaneously generate high-pressure gas in the supply pipe 40, and the pressure of the gas moves each switching plate 42 to the left, and the pair of sub torsions 22 are moved leftward via each moving plate 44 and each moving shaft 44A (see FIG. 5A ). This causes the pair of sub torsions 22 (sub gears 22A) to disengage from the stopper base 26 (stopper gear 26B). For this reason, when the pulling load from the spool 16 onto the webbing 18 from the occupant (for example, a load acting on the webbing 18 from the occupant's shoulder) is equal to or greater than the force limiter load, which is the torsional load resistance F1 of the main torsion 20 (see FIG. 5B ), the main torsion 20 is torsionally deformed, allowing rotation of the spool 16 in the unwinding direction relative to the pinion 30 and the stopper base 26 and allowing the webbing 18 to be unwound from the spool 16. As a result, the force limiter load is reduced and the kinetic energy of the occupant is absorbed by the torsional deformation of the main torsion 20, thereby appropriately protecting small occupants.

[0048] Here, the switching mechanism 34 switches between operation (torsional deformation) and non-operation of each of the pair of sub-torsion members 22. This increases the number of stages over which the force limiter load (the load that allows the webbing 18 to be pulled out from the spool 16) can be changed (to three stages: high load, medium load, and low load).

[0049] Furthermore, when a vehicle collision is detected, which occurs before the main torsion 20 and the sub torsion 22 are torsionally deformed (before the webbing 18 is allowed to be pulled out from the spool 16) or when the main torsion 20 and the sub torsion 22 have started torsionally deform, the switching mechanism 34 switches between operation and non-operation of the pair of sub torsions 22. This allows the force limiter load to be adjusted early.

[0050] Furthermore, the main torsion 20 and the sub-torsion 22 are made of soft iron, and the stopper base 26 is made of iron, so that the strength of the stopper base 26 (including the stopper gear 26B) is made higher than the strength of the main torsion 20 and the sub-torsion 22. This makes it possible to suppress deformation of the stopper base 26 (especially the stopper gear 26B), and torsional deformation of the main torsion 20 and the sub-torsion 22 can be favorably suppressed. Moreover, deformation of the stopper base 26 can be suppressed without increasing the size of the stopper base 26, and the stopper base 26 can be made smaller.

[0051] Furthermore, the main torsion 20 and the sub-torsion 22 are made of soft iron, and the main gear 20A of the main torsion 20 and the sub-gear 22A of the sub-torsion 22 are made of iron, so that the strength of the main gear 20A and the sub-gear 22A is higher than the strength of the main torsion 20 and the sub-torsion 22. This makes it possible to suppress deformation of the main gear 20A and the sub-gear 22A, and torsional deformation of the main torsion 20 and the sub-torsion 22 can be favorably suppressed. Moreover, deformation of the main gear 20A and the sub-gear 22A can be suppressed without increasing the size of the main gear 20A and the sub-gear 22A, and the main gear 20A and the sub-gear 22A can be made smaller.

[0052] Furthermore, the main torsion 20 and the sub torsion 22 are disposed within the spool 16. This allows the webbing take-up device 10 to be made smaller in size.

[0053] Furthermore, the stopper tube 24 and the stopper 28 are fitted between the peripheral surface of the arrangement hole 16A of the spool 16 and the threaded column 26A of the stopper base 26. This increases the strength of the portion between the spool 16 and the stopper base 26.

[0054] Furthermore, the switching mechanism 34 is disposed on the opposite side of the spool 16 from the stopper base 26. Therefore, the switching mechanism 34 can be easily disposed in the webbing take-up device 10.

[0055] In the present embodiment, in a state in which the force limiter load is set to a high load, at least one gas generator 38 may be activated to stop the torsional deformation of at least one sub-torsion 22 while the webbing 18 is being permitted to be unwound from the spool 16 (see the dashed arrow in FIG. 3B ). This makes it possible to vary (reduce) the force limiter load while the webbing 18 is being permitted to be unwound from the spool 16.

[0056] Furthermore, in the present embodiment, in a state in which the force limiter load is set to a medium load, the other gas generator 38 may be activated to stop the torsional deformation of the other sub-torsion 22 while the webbing 18 is being permitted to be unwound from the spool 16 (see the dashed arrow in FIG. 4B ). This makes it possible to vary (reduce) the force limiter load while the webbing 18 is being permitted to be unwound from the spool 16.

[0057] Second Embodiment FIG. 6 shows a cross-sectional view of a webbing take-up device 50 according to a second embodiment of the present invention, as viewed from the front.

[0058] The webbing take-up device 50 according to this embodiment has substantially the same configuration as that of the first embodiment, but differs in the following respects.

[0059] 6, in the webbing take-up device 50 according to this embodiment, the stopper base 26 is a ratchet gear, and ratchet teeth 14B are formed on the entire outer periphery of the stopper base 26 (see FIGS. 9A, 10A, 10B, and 15A). The lock plate 30A is rotatably supported by the cover plate 14 instead of the pinion 30 (see FIG. 7A).

[0060] The screw shaft 32 is coaxially fitted into the pinion 30 and the stopper base 26, and the left end of the screw shaft 32 is coaxially inserted into and screwed onto the spool 16 (see FIG. 13A). As a result, the pinion 30 and the stopper base 26 are sandwiched between the right part of the screw shaft 32 and the spool 16 (see FIGS. 14A and 14B).

[0061] A substantially cylindrical fixed barrel 52 (see FIGS. 16, 17, 18A, and 18B) is coaxially and integrally rotatably connected to the left side of the left end of each sub-torsion 22 (see FIG. 13B), and the fixed barrel 52 is rotatably fitted into the insertion hole 16B of the spool 16. A plate-shaped fixed piece 54 is inserted and fitted into the fixed barrel 52 and the spool 16, and the portion of the fixed piece 54 inserted into the fixed barrel 52 has a substantially triangular plate shape. The fixed piece 54 restricts the rotation of the fixed barrel 52, and the radially outer surface of the fixed piece 54 in the spool 16 is flush with the outer peripheral surface of the spool 16.

[0062] A pair of substantially annular plate-shaped restricting rings 56 (see FIGS. 12 , 14A , 14B , 15B , and 16 ) are fitted to the outer periphery of the spool 16. The restricting rings 56 abut against the radially outer surfaces of the fixing pieces 54 in the spool 16 direction, restricting radially outward movement of the fixing pieces 54 in the spool 16 direction. A pair of retaining plates 58 each having a substantially U-shaped cross section are attached to the outer periphery of the spool 16, with the central portions of the retaining plates 58 located on the left side of the spool 16. The connecting shaft 46 passes through the central portion of the retaining plate 58, and the central portion of the retaining plate 58 is engaged from the left side by the axially intermediate portion of the connecting shaft 46. Both sides of the retaining plate 58 are sandwiched between the restricting rings 56 and the spool 16, and the retaining plate 58 holds the restricting ring 56 to the spool 16.

[0063] In the switching mechanism 34 (see FIGS. 9B , 10C , 11 , and 12 ), the left portion of the spool 16 is rotatably inserted into a pair of cases 36, and a restricting ring 56 is disposed inside the annular case 36. A circular, rectangular-sectioned communication hole 60 is formed inside the case 36. The communication hole 60 is disposed to the left of the restricting ring 56 and communicates with the gas generator 38 at its radially outer side. A switching plate 42 (hover) is fitted into the communication hole 60, and the switching plate 42 has a J-shaped cross section. The interior of the switching plate 42 is open to the left and radially outward, and the interior of the switching plate 42 is communicated with the gas generator 38 at its radially outer side.

[0064] Incidentally, in the event of a vehicle collision, the sensor mechanism is activated and the lock plate 30A of the cover plate 14 meshes with the ratchet teeth 14B of the stopper base 26 (ratchet gear), restricting rotation of the stopper base 26 in the pull-out direction. As a result, the main torsion 20 and the pair of sub-torsion 22 restrict rotation of the spool 16 in the pull-out direction, restricting pull-out of the webbing 18 from the spool 16, and the occupant is restrained by the webbing 18.

[0065] If the occupant is of large build (if the body size sensor detects that the occupant is of large build), the switching mechanism 34 does not activate the pair of gas generators 38 when a vehicle collision is detected, and the rotation restriction on the left end of the main torsion 20 and the rotation restriction by the left ends of the pair of sub-torsion members 22 and the fixed piece 54 of the fixed cylinder 52 are maintained (see FIG. 7A ). Therefore, when the pulling load from the spool 16 onto the webbing 18 from the occupant (for example, the load applied to the webbing 18 from the occupant's shoulders) is equal to or greater than the force limiter load which is the total load of the torsional resistance load F1 of the main torsion member 20 and the torsional resistance load F2 of the pair of sub-torsion members 22 (see FIG. 7B ), the main torsion member 20 and the pair of sub-torsion members 22 are torsionally deformed, allowing the spool 16 to rotate in the unwinding direction relative to the stopper base 26, and allowing the webbing 18 to be unwound from the spool 16. As a result, the force limiter load is increased, and the kinetic energy of the occupant is absorbed by the torsional deformation of the main torsion 20 and the pair of sub-torsion 22, thereby providing adequate protection for large occupants.

[0066] If the occupant is of medium build (if the build sensor detects that the occupant is of medium build), in the switching mechanism 34, when a vehicle collision is detected, one gas generator 38 is activated to instantaneously generate high-pressure gas inside the switching plate 42, causing the one switching plate 42 to move to the right due to the pressure of the gas, and moving the one restricting ring 56 to the right (see FIG. 8A ). As a result, the restriction on the movement of the one fixed piece 54 radially outward of the spool 16 by the one restricting ring 56 is released, and the restriction on rotation by the left end of the one sub-torsion 22 and the fixed piece 54 of the fixed barrel 52 is released. For this reason, when the pulling load from the spool 16 onto the webbing 18 from the occupant (for example, a load acting on the webbing 18 from the occupant's shoulder) is equal to or greater than the force limiter load, which is the total load of the torsional resistance load F1 of the main torsion 20 and the torsional resistance load F2 of the other sub-torsion 22 (see FIG. 8B ), the main torsion 20 and the other sub-torsion 22 are torsionally deformed, allowing rotation of the spool 16 in the unwinding direction relative to the stopper base 26 and allowing unwinding of the webbing 18 from the spool 16. As a result, the force limiter load is set to a medium load, and the kinetic energy of the occupant is absorbed by the torsional deformation of the main torsion 20 and the other sub-torsion 22, so that the medium-sized occupant is appropriately protected.

[0067] If the occupant is small in stature (if the physique sensor detects that the occupant is small in stature), in the switching mechanism 34, when a vehicle collision is detected, the pair of gas generators 38 are activated to instantaneously generate high-pressure gas inside the switching plates 42, causing the switching plates 42 to move to the right due to the pressure of the gas, and moving the pair of restricting rings 56 to the right. As a result, the restriction on the movement of the pair of fixed pieces 54 radially outward in the spool 16 by the pair of restricting rings 56 is released, and the restriction on rotation by the left ends of the pair of sub-torsion elements 22 and the fixed pieces 54 of the fixed barrel 52 is released. For this reason, when the pulling load from the spool 16 onto the webbing 18 from the occupant (for example, a load acting on the webbing 18 from the occupant's shoulder) is equal to or greater than the force limiter load, which is the torsional load resistance F1 of the main torsion 20 (see FIG. 8C ), the main torsion 20 is torsionally deformed, allowing rotation of the spool 16 in the unwinding direction relative to the stopper base 26 and allowing the webbing 18 to be unwound from the spool 16. As a result, the force limiter load is reduced and the kinetic energy of the occupant is absorbed by the torsional deformation of the main torsion 20, thereby appropriately protecting small occupants.

[0068] Here, this embodiment can also achieve the same functions and effects as the first embodiment.

[0069] In the present embodiment, in a state in which the force limiter load is set to a high load, at least one gas generator 38 may be activated to stop the torsional deformation of at least one sub-torsion 22 while the webbing 18 is being permitted to be unwound from the spool 16 (see the dashed arrow in FIG. 7B ). This makes it possible to vary (reduce) the force limiter load while the webbing 18 is being permitted to be unwound from the spool 16.

[0070] Furthermore, in the present embodiment, in a state in which the force limiter load is set to a medium load, the other gas generator 38 may be activated to stop the torsional deformation of the other sub-torsion 22 while the webbing 18 is being permitted to be unwound from the spool 16 (see the dashed arrow in FIG. 8B ). This makes it possible to vary (reduce) the force limiter load while the webbing 18 is being permitted to be unwound from the spool 16.

[0071] Furthermore, in the present embodiment, the switching plate 42 has a J-shaped cross section. However, the switching plate 42 may have a rectangular cross section, and the left surface of the switching plate 42 may be inclined toward the right as it extends radially outward of the switching plate 42.

[0072] In the first and second embodiments, the pair of sub-torsion members 22 have the same torsional load resistance. However, the torsional load resistance of one sub-torsion member 22 may be smaller or larger than the torsional load resistance of the other sub-torsion member 22.

[0073] Furthermore, in the first and second embodiments, the torsional load resistance of the sub torsion 22 is set smaller than the torsional load resistance of the main torsion 20. However, the torsional load resistance of the sub torsion 22 may be set equal to or greater than the torsional load resistance of the main torsion 20.

[0074] Third Embodiment FIG. 19 shows a cross-sectional view of a webbing take-up device 70 according to a third embodiment of the present invention, as viewed from the front.

[0075] The webbing take-up device 70 according to this embodiment has substantially the same configuration as that of the second embodiment, but differs in the following respects.

[0076] As shown in FIG. 19, a webbing take-up device 70 according to this embodiment is not provided with a stopper tube 24 and a stopper 28.

[0077] A substantially cylindrical stopper gear 26B (see FIGS. 20A, 20B, and 21) is integrally and coaxially provided near the outer periphery of the stopper base 26, and the stopper gear 26B protrudes to the left and is rotatably fitted into the arrangement hole 16A of the spool 16. An internal gear is provided around the entire inner periphery of the inner periphery of the stopper gear 26B, and the stopper gear 26B (internal gear) is meshed with the main gear 20A of the main torsion 20 and the sub gears 22A of the pair of sub torsions 22. The main gear 20A and the sub gears 22A are supported by the stopper base 26 (the stopper gear 26B and the threaded column 26A) and the spool 16 (the inner surface of the arrangement hole 16A).

[0078] The torsional load resistance of one sub-torsion 22 is set to be greater than the torsional load resistance of the other sub-torsion 22 , and the torsional load resistance of the other sub-torsion 22 is set to be the same as the torsional load resistance of the main torsion 20 .

[0079] Incidentally, in the event of a vehicle collision, the sensor mechanism is activated and the lock plate 30A of the cover plate 14 meshes with the ratchet teeth 14B of the stopper base 26 (ratchet gear), restricting rotation of the stopper base 26 in the pull-out direction. As a result, the main torsion 20 and the pair of sub-torsion 22 restrict rotation of the spool 16 in the pull-out direction, restricting pull-out of the webbing 18 from the spool 16, and the occupant is restrained by the webbing 18.

[0080] If the occupant is of large build (if the build sensor detects that the occupant is of large build), the pair of gas generators 38 are not activated in the switching mechanism 34 when a vehicle collision is detected, and rotation restriction by the left end of the main torsion 20 and the left ends of the pair of sub-torsion 22 and the fixed piece 54 of the fixed cylinder 52 is maintained. For this reason, when the pulling load from the spool 16 onto the webbing 18 from the occupant (for example, a load acting on the webbing 18 from the occupant's shoulders) is equal to or greater than the force limiter load, which is the total load of the torsional load resistance F1 of the main torsion 20, the torsional load resistance F1 of the other sub-torsion 22, and the torsional load resistance F2 of one sub-torsion 22 (see FIG. 22A ), the main torsion 20 and the pair of sub-torsion 22 are torsionally deformed, allowing rotation of the spool 16 in the unwinding direction relative to the stopper base 26 and allowing unwinding of the webbing 18 from the spool 16. As a result, the force limiter load is set to a high load, and the kinetic energy of the occupant is absorbed by the torsional deformation of the main torsion 20 and the pair of sub-torsion 22, thereby appropriately protecting a large occupant.

[0081] If the occupant is of medium build (if the build sensor detects that the occupant is of medium build), in the switching mechanism 34, when a vehicle collision is detected, one gas generator 38 is activated to instantaneously generate high-pressure gas inside the switching plate 42, and the pressure of the gas moves one switching plate 42 to the right, moving one restricting ring 56 to the right. As a result, the restriction on the movement of one fixed piece 54 radially outward of the spool 16 by one restricting ring 56 is released, and the restriction on rotation by the left end of one sub-torsion 22 and the fixed piece 54 of the fixed barrel 52 is released. For this reason, when the pulling load from the spool 16 onto the webbing 18 from the occupant (for example, a load acting on the webbing 18 from the occupant's shoulder) is equal to or greater than the force limiter load, which is the total load of the torsional resistance load F1 of the main torsion 20 and the torsional resistance load F1 of the other sub-torsion 22 (see FIG. 22B ), the main torsion 20 and the other sub-torsion 22 are torsionally deformed, allowing rotation of the spool 16 in the unwinding direction relative to the stopper base 26 and allowing unwinding of the webbing 18 from the spool 16. As a result, the force limiter load is set to a medium load, and the kinetic energy of the occupant is absorbed by the torsional deformation of the main torsion 20 and the other sub-torsion 22, so that the medium-sized occupant is appropriately protected.

[0082] If the occupant is small in stature (if the physique sensor detects that the occupant is small in stature), in the switching mechanism 34, when a vehicle collision is detected, the pair of gas generators 38 are activated to instantaneously generate high-pressure gas inside the switching plates 42, causing the switching plates 42 to move to the right due to the pressure of the gas, and moving the pair of restricting rings 56 to the right. As a result, the restriction on the movement of the pair of fixed pieces 54 radially outward in the spool 16 by the pair of restricting rings 56 is released, and the restriction on rotation by the left ends of the pair of sub-torsion elements 22 and the fixed pieces 54 of the fixed barrel 52 is released. For this reason, when the pulling load from the spool 16 onto the webbing 18 from the occupant (for example, a load acting on the webbing 18 from the occupant's shoulder) is equal to or greater than the force limiter load, which is the torsional load resistance F1 of the main torsion 20 (see FIG. 22C ), the main torsion 20 is torsionally deformed, allowing rotation of the spool 16 in the unwinding direction relative to the stopper base 26 and allowing the webbing 18 to be unwound from the spool 16. As a result, the force limiter load is reduced and the kinetic energy of the occupant is absorbed by the torsional deformation of the main torsion 20, thereby appropriately protecting small occupants.

[0083] Here, this embodiment can also achieve the same functions and effects as the first embodiment.

[0084] Furthermore, the stopper gear 26B (internal gear) is meshed radially inside with the main gear 20A of the main torsion 20 and the sub gears 22A of the pair of sub torsions 22. Therefore, the main torsion 20 and the pair of sub torsions 22 can be arranged close to each other radially inside the stopper gear 26B, and the spool 16 can be made smaller in the radial direction and lighter in weight.

[0085] In the present embodiment, in a state in which the force limiter load is set to a high load, at least one gas generator 38 may be activated (for example, a pair of gas generators 38 may be activated simultaneously or at intervals) to stop the torsional deformation of at least one sub-torsion 22 while the webbing 18 is being permitted to be unwound from the spool 16 (see FIGS. 23A, 23B, and 23C). This makes it possible to vary (reduce) the force limiter load while the webbing 18 is being permitted to be unwound from the spool 16.

[0086] Furthermore, in the present embodiment, in a state where the force limiter load is set to a medium load, the other gas generator 38 may be activated to stop the torsional deformation of the other sub-torsion 22 while the webbing 18 is being permitted to be unwound from the spool 16 (see FIG. 23D ). This makes it possible to vary (reduce) the force limiter load while the webbing 18 is being permitted to be unwound from the spool 16.

[0087] In this embodiment, the torsional load resistance of one sub-torsion 22 is set to be greater than the torsional load resistance of the other sub-torsion 22. However, the torsional load resistance of one sub-torsion 22 may be the same as or smaller than the torsional load resistance of the other sub-torsion 22.

[0088] Furthermore, in this embodiment, the torsional load resistance of the other sub-torsion 22 is set to be the same as the torsional load resistance of the main torsion 20. However, the torsional load resistance of the other sub-torsion 22 may be greater or smaller than the torsional load resistance of the main torsion 20.

[0089] The disclosure of Japanese Patent Application No. 2024-81780, filed on May 20, 2024, is incorporated herein by reference in its entirety.

[0090] 10... Webbing retractor, 16... Spool, 18... Webbing, 20... Main torsion (deformable member), 20A... Main gear (gear portion), 22... Sub torsion (deformable member), 22A... Sub gear (gear portion), 26... Stopper base (regulating gear), 34... Switching mechanism, 50... Webbing retractor, 70... Webbing retractor

Claims

1. A webbing retractor comprising: a spool onto which a webbing to be worn by an occupant is wound, and which rotates in the unwinding direction as the webbing is unwound; a regulating gear capable of regulating rotation; a plurality of deformable members disposed within the spool, engaged with the regulating gear, and which are torsionally deformed when rotation of the regulating gear is regulated, thereby allowing rotation of the spool in the unwinding direction; and a switching mechanism which switches between operating and non-operating states of each of the plurality of deformable members.

2. A webbing take-up device according to claim 1, wherein the switching mechanism switches between operating and non-operating states of the deformable member before or when the deformable member is torsionally deformed.

3. A webbing take-up device according to claim 1, wherein the switching mechanism is disposed on the opposite side of the spool from the regulating gear.

4. A webbing retractor comprising: a spool onto which a webbing to be worn by an occupant is wound, and which rotates in the unwinding direction as the webbing is unwound; a regulating gear that can regulate rotation; and a plurality of deformable members that are disposed within the spool, engage with the regulating gear, and have a strength that is lower than that of the regulating gear, and that are torsionally deformed when the rotation of the regulating gear is regulated, thereby allowing the spool to rotate in the unwinding direction.

5. A webbing take-up device according to claim 1 or 4, further comprising a gear portion provided on the deformable member, meshed with the regulating gear, and having a strength greater than that of the deformable member.

6. A webbing take-up device according to claim 1 or claim 4, wherein the restricting gear is engaged with the deformable member on the inner side in the direction of the rotational diameter.

7. A webbing take-up device according to claim 6, wherein the restricting gear is engaged with a plurality of the deformable members on the inner side in the rotational radial direction.

8. A webbing take-up device according to claim 1 or claim 4, wherein the switching mechanism always operates at least one of the deformation members.

9. A webbing take-up device according to claim 1 or 4, wherein the plurality of deformable members have different resistances to torsional deformation loads.

10. A webbing take-up device according to claim 1 or claim 4, wherein the switching mechanism switches between fixing and not fixing one end of the deformable member.

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