Webbing take-up device

Abstract

To enable a second member to be operable at an early stage.SOLUTION: In a webbing take-up device 10, when rotation of a pinion 28 and a stopper base 24 in a pulling-out direction is restricted, main torsion 22 is torsionally deformed, and an actuating mechanism 42 is actuated to torsionally deform sub torsion 36, thereby allowing webbing 20 to be pulled out from a spool 16. Here, torsional deformation of the main torsion 22 is started, and the actuating mechanism 42 is actuated. Accordingly, the sub torsion 36 can be made operable at an early stage.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[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 restricting body in the unwinding direction is restricted. [Background technology]

[0002] In the belt retractor described in Patent Document 1 below, a first force-limiting element is connected to the belt shaft and the shaping head, and when rotation of the shaping head in the unwinding direction is restricted, the first force-limiting element is torsionally deformed, allowing rotation of the belt shaft in the unwinding direction. Furthermore, a second force-limiting element is arranged coaxially with the first force-limiting element, and when a drive element is operated, the second force-limiting element is torsionally deformed, allowing rotation of the belt shaft in the unwinding direction.

[0003] However, in such a belt retractor, it may be preferable to be able to make the second force-limiting element operable early. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2021-531200 Summary of the Invention [Problem to be solved by the invention]

[0005] In consideration of the above circumstances, an object of the present invention is to provide a webbing take-up device that can quickly make the second member operable. [Means for solving the problem]

[0006] 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 around which the webbing is pulled out and rotated in the pull-out direction; a regulating body that is capable of restricting rotation in the pull-out direction; a first member that is connected to the spool and the regulating body and that is torsionally deformed when rotation of the regulating body in the pull-out direction is restricted, thereby allowing rotation of the spool in the pull-out direction; an operating mechanism that is activated when torsional deformation of the first member begins; and a plurality of second members, at least one of which is positioned in a position not coaxial with the first member, and that is torsionally deformed when the operating mechanism is activated, thereby allowing rotation of the spool in the pull-out direction.

[0007] A webbing take-up device according to a second aspect of the present invention is the webbing take-up device according to the first aspect of the present invention, further comprising a switching mechanism that switches between operating and non-operating states of the second member.

[0008] A webbing take-up device of a third aspect of the present invention is the webbing take-up device of the second aspect of the present invention, wherein the switching mechanism switches between operating and non-operating of the second member before the first member is torsionally deformed or when the first member is torsionally deformed.

[0009] A webbing take-up device of a fourth aspect of the present invention is the webbing take-up device of any one of the first to third aspects of the present invention, wherein the second member is disposed axially outward of the spool.

[0010] 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, wherein the second member is disposed radially outward of the spool. [Effects of the Invention]

[0011] In a webbing take-up device according to a first aspect of the present invention, a webbing to be worn by an occupant is wound onto a spool, and as the webbing is unwound from the spool, the spool rotates in the unwound direction. A first member is connected to the spool and a restrictor, and when rotation of the restrictor in the unwound direction is restricted, the first member is torsionally deformed, allowing rotation of the spool in the unwound direction. Furthermore, at least one of a plurality of second members is disposed in a position that is not coaxial with the first member, and when an actuation mechanism is actuated, the second member is torsionally deformed, allowing rotation of the spool in the unwound direction.

[0012] At this point, the first member begins to twist and the actuation mechanism is activated, allowing the second member to become operable quickly.

[0013] In the webbing take-up device of the second aspect of the present invention, the switching mechanism switches between operating and non-operating of the second member, thereby making it possible to change the force limiter load (the load that allows the webbing to be pulled out from the spool).

[0014] In the webbing take-up device of the third aspect of the present invention, the switching mechanism switches between operating and inoperating the second member before or when the first 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 fourth aspect of the present invention, the second member is disposed axially outward of the spool, which makes it easy to position the second member.

[0016] In the webbing take-up device of the fifth aspect of the present invention, the second member is disposed radially outward from the spool, which makes it easy to position the second member. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view showing a webbing take-up device according to a first embodiment of the present invention, as viewed from the front. [Figure 2]FIG. 1A is a cross-sectional view seen from the front showing 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, and FIG. 1B is a graph showing the relationship between the webbing pull-out stroke (chest movement amount S, horizontal axis) of the webbing take-up device and the force limiter load (shoulder load F, vertical axis). [Figure 3] 1A is a cross-sectional view seen from the front showing 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, and FIG. 1B is a graph showing the relationship between the webbing withdrawal stroke (chest movement amount S, horizontal axis) of the webbing take-up device and the force limiter load (shoulder load F, vertical axis). [Figure 4] FIG. 1A is a cross-sectional view seen from the front showing 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, and FIG. 1B is a graph showing the relationship between the webbing withdrawal stroke (chest movement amount S, horizontal axis) of the webbing take-up device and the force limiter load (shoulder load F, vertical axis). [Figure 5] FIG. 6 is a cross-sectional view showing a webbing take-up device according to a second embodiment of the present invention, as viewed from the front. [Figure 6] 10A is a cross-sectional view seen from the front showing when the force limiter load of a webbing take-up device according to a second embodiment of the present invention is set to a high load, and FIG. 10B is a graph showing the relationship between the webbing withdrawal stroke (chest movement amount S, horizontal axis) of the webbing take-up device and the force limiter load (shoulder load F, vertical axis). [Figure 7] 10A is a cross-sectional view seen from the front showing when the force limiter load of a webbing take-up device according to a second embodiment of the present invention is set to a medium load, and FIG. 10B is a graph showing the relationship between the webbing withdrawal stroke (chest movement amount S, horizontal axis) and the force limiter load (shoulder load F, vertical axis) of the webbing take-up device. [Figure 8]10A is a cross-sectional view seen from the front showing 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, and FIG. 10B is a graph showing the relationship between the webbing withdrawal stroke (chest movement amount S, horizontal axis) and the force limiter load (shoulder load F, vertical axis) of the webbing take-up device. [Figure 9] FIG. 10 is a cross-sectional view showing a webbing take-up device according to a third embodiment of the present invention, as viewed from the front. [Figure 10] 10A is a cross-sectional view seen from the front showing when the force limiter load of a webbing take-up device according to a third embodiment of the present invention is set to a high load, and FIG. 10B is a graph showing the relationship between the webbing withdrawal stroke (chest movement amount S, horizontal axis) of the webbing take-up device and the force limiter load (shoulder load F, vertical axis). [Figure 11] 10A is a cross-sectional view seen from the front showing the state when the force limiter load of a webbing take-up device according to a third embodiment of the present invention is set to a medium load, and FIG. 10B is a graph showing the relationship between the webbing withdrawal stroke (chest movement amount S, horizontal axis) and the force limiter load (shoulder load F, vertical axis) of the webbing take-up device. [Figure 12] 10A is a cross-sectional view seen from the front showing when the force limiter load of a webbing take-up device according to a third embodiment of the present invention is set to a low load, and FIG. 10B is a graph showing the relationship between the webbing withdrawal stroke (chest movement amount S, horizontal axis) of the webbing take-up device and the force limiter load (shoulder load F, vertical axis). [Figure 13] FIG. 10 is a cross-sectional view showing a webbing take-up device according to a fourth embodiment of the present invention, as viewed from the front. [Figure 14] 10A is a cross-sectional view seen from the front showing when the force limiter load of a webbing take-up device according to a fourth embodiment of the present invention is set to a high load, and FIG. 10B is a graph showing the relationship between the webbing pull-out stroke (chest movement amount S, horizontal axis) of the webbing take-up device and the force limiter load (shoulder load F, vertical axis). [Figure 15]10A is a cross-sectional view seen from the front showing the state when the force limiter load of a webbing take-up device according to a fourth embodiment of the present invention is set to a medium load, and FIG. 10B is a graph showing the relationship between the webbing withdrawal stroke (chest movement amount S, horizontal axis) and the force limiter load (shoulder load F, vertical axis) of the webbing take-up device. [Figure 16] 10A is a cross-sectional view seen from the front showing when the force limiter load of a webbing take-up device according to a fourth embodiment of the present invention is set to a low load, and FIG. 10B 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) of the webbing take-up device. DETAILED DESCRIPTION OF THE INVENTION

[0018] [First embodiment] 1 shows a cross-sectional view of a webbing take-up device 10 according to a first embodiment of the present invention as seen from the front. In the drawing, the right side of the webbing take-up device 10 is indicated by an arrow RH, and the upper side of the webbing take-up device 10 is indicated by an arrow UP.

[0019] 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.

[0020] 1, the webbing retractor 10 is provided with a frame 12 having a U-shaped cross section as a support body, and the frame 12 is provided with a rear back plate (not shown), a left leg plate 12A, and a right leg plate 12B. The frame 12 is fixed to the vehicle body at the back plate, thereby installing the webbing retractor 10 on the vehicle.

[0021] A box-shaped cover plate 14 serving as a restricting member is fixed to the right side of the frame 12 (leg plate 12B), and the interior of the cover plate 14 is open to the left and closed from the left side by the leg plate 12A. 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 circumferential surface of the ratchet hole 14A.

[0022] A substantially cylindrical spool 16 is rotatably supported between the leg plates 12A and 12B of the frame 12, with the left and right ends of the spool 16 penetrating the leg plates 12A and 12B, respectively. A non-circular stopper hole 18, as viewed from the front, is formed coaxially on the right surface of the spool 16, and the stopper hole 18 is open to the right.

[0023] A long, strip-shaped webbing 20 is wound around the spool 16 from the base end in the longitudinal direction, and as the spool 16 rotates in the winding direction, the webbing 20 is wound onto the spool 16, and as the webbing 20 is pulled out from the spool 16, the spool 16 rotates in the unwinding direction. Furthermore, as the webbing 20 is pulled out from the spool 16, the webbing 20 is worn by an occupant seated in a vehicle seat (not shown). When the webbing 20 is worn by the occupant, the webbing 20 is hung 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 is also hung 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.

[0024] A metallic, substantially cylindrical main torsion 22 (main torsion shaft) serving as a first member (first energy absorbing member) is coaxially disposed within the spool 16. A portion near the left end of the main torsion 22 is connected to the spool 16 so as to be rotatable therewith, thereby allowing the main torsion 22 to rotate integrally with the spool 16. A portion near the left end of the main torsion 22 is engaged with the spool 16 from the left side, thereby restricting rightward movement of the main torsion 22, and the right end of the main torsion 22 is disposed in the stopper hole 18 of the spool 16. A substantially cylindrical screw hole 22A is formed coaxially at the right end of the main torsion 22, and the screw hole 22A is open to the right.

[0025] A substantially annular plate-shaped stopper base 24, serving as a connecting member constituting a regulating body, is coaxially disposed on the right side of the spool 16. A cylindrical connecting tube 24A is integrally and coaxially disposed at the center of the stopper base 24. The connecting tube 24A protrudes to the left and is coaxially inserted into the stopper hole 18 of the spool 16. The right end of the main torsion 22 is connected to the connecting tube 24A so as to be rotatable therewith. The inner periphery of an annular plate-shaped stopper 26 is threadedly engaged with the outer periphery of the connecting tube 24A, and the outer periphery of the stopper 26 is non-circular. The outer periphery of the stopper 26 is fitted into the circumferential surface of the stopper hole 18, so that the stopper 26 can rotate integrally with the spool 16. The stopper 26 is disposed at the left end of the connecting tube 24A. When the spool 16 is rotated in the pull-out direction relative to the stopper base 24, the stopper 26 rotates integrally with the spool 16 in the pull-out direction and moves to the right. When the stopper 26 abuts against the stopper base 24, the rotation of the spool 16 relative to the stopper base 24 in the pull-out direction is restricted.

[0026] A substantially annular plate-shaped pinion 28 serving as a regulated member constituting the regulating body is coaxially provided on the right side of the stopper base 24, and the pinion 28 is connected to the stopper base 24 so as to be rotatable together with the stopper base 24, allowing the spool 16, main torsion 22, stopper base 24, and pinion 28 to rotate together. The pinion 28 is coaxially inserted through the ratchet hole 14A of the cover plate 14, and a lock plate 28A serving as a regulated part is rotatably supported on the pinion 28.

[0027] A substantially cylindrical screw shaft 30 is coaxially fitted into the stopper base 24 and the pinion 28, and the right portion of the screw shaft 30 is engaged with the pinion 28 from the right side. The left end of the screw shaft 30 is threadedly engaged with the circumferential surface of the threaded hole 22A of the main torsion 22, whereby the stopper base 24 and the pinion 28 are sandwiched between the right portion of the screw shaft 30 and the spool 16.

[0028] 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 28A of the pinion 28. In the event of a vehicle collision (in the event of a vehicle emergency, such as sudden deceleration of the vehicle or sudden withdrawal of the webbing 20 from the spool 16), the sensor mechanism is activated and the lock plate 28A is rotated radially outward of the pinion 28, whereby the lock plate 28A meshes with the ratchet teeth 14B of the cover plate 14 (ratchet hole 14A), restricting (locking) rotation of the pinion 28 in the withdrawal direction. This restricts rotation of the stopper base 24 in the withdrawal direction, and the main torsion 22 restricts rotation of the spool 16 in the withdrawal direction.

[0029] A cylindrical box-shaped case 32 serving as a housing is coaxially provided on the left side of the spool 16, and the left end of the main torsion 22 is coaxially inserted into the case 32. A substantially cylindrical connecting shaft 34 is coaxially arranged within the case 32, and the left portion of the connecting shaft 34 penetrates the left wall of the case 32 and the right portion is inserted into the right wall of the case 32, so that the connecting shaft 34 is rotatably supported by the case 32. The right portion of the connecting shaft 34 is cylindrical, and the left end of the main torsion 22 is fitted inside, so that the connecting shaft 34 is connected to the main torsion 22 so as to be rotatable together with it. A connecting gear 34A is provided integrally with the connecting shaft 34 at an axial (left-right) intermediate portion, and the connecting gear 34A is coaxially enlarged in diameter relative to the connecting shaft 34.

[0030] A pair of metallic, substantially cylindrical sub-torsion members 36 (sub-torsion shafts) serving as a second member (second energy absorbing member) are arranged on the periphery within the case 32, with the axial direction of the sub-torsion members 36 extending in the left-right direction. The right end of the sub-torsion member 36 is non-rotatably supported by the right wall of the case 32, allowing the sub-torsion member 36 to move in the left-right direction. A spring 38 (compression coil spring) is stretched between the right end of the sub-torsion member 36 and the right wall of the case 32, and the sub-torsion member 36 is biased leftward by the spring 38 and abuts against the left wall of the case 32. The left end of the sub-torsion member 36 is meshed with a connecting gear 34A of the connecting shaft 34, and the case 32 is connected to the spool 16 via the sub-torsion member 36, the connecting shaft 34, and the main torsion member 22, and rotates integrally with the spool 16. The torsional load resistance of the pair of sub-torsion elements 36 is set to be the same, and the torsional load resistance of the sub-torsion elements 36 is set to be smaller than the torsional load resistance of the main torsion elements 22 .

[0031] A rod-shaped moving rod 40 is coaxially connected to the left end of the sub-torsion 36, and the moving rod 40 penetrates the left wall of the case 32 and is supported so as to be movable in the left-right direction. One of the moving rods 40 is bent in a crank shape, and the left portion of one moving rod 40 is disposed radially outward of the other moving rod 40 from the case 32.

[0032] The webbing retractor 10 is provided with an operating mechanism 42.

[0033] The operating mechanism 42 is provided with a long, rod-shaped metallic trigger wire 44 as an operating part, and the trigger wire 44 passes through the peripheral wall of the spool 16 and the peripheral part of the stopper base 24 in the left-right direction. The right end of the trigger wire 44 is engaged with the stopper base 24 from the right side, and the left end of the trigger wire 44 protrudes to the left side of the spool 16.

[0034] A substantially annular plate-shaped actuating plate 46 serving as an actuating member is coaxially supported between the spool 16 and the case 32. The actuating plate 46 is rotatable and biased in the winding direction (or the unwinding direction) relative to the case 32. The left end of a trigger wire 44 passes through and is fitted into the periphery of the actuating plate 46, and the trigger wire 44 restricts rotation in the winding direction relative to the case 32 due to the biasing force of the actuating plate 46. A substantially cylindrical actuating cylinder 46A is integrally provided on the outer periphery of the actuating plate 46, and the actuating cylinder 46A protrudes leftward and is disposed radially outward from the case 32. A plurality of substantially rectangular actuating holes 46B are formed through the actuating cylinder 46A. The plurality of actuating holes 46B are provided at equal intervals around the circumferential direction of the actuating plate 46 and are open to the left.

[0035] A plurality of plate-shaped clutches 48 serving as engaging members are supported on the outer periphery of the case 32. The plurality of clutches 48 are provided at equal intervals around the circumferential direction of the case 32 and are rotatable within a predetermined range around their base ends. The clutches 48 are fitted into actuation holes 46B in the actuation plate 46 (actuation cylinder 46A), which limits the rotation of the clutches 48 radially outward from the case 32. In addition, flat knurled teeth are formed on the tip surface of the clutches 48.

[0036] A cylindrical lock ring 50 serving as an engaged member is coaxially arranged on the outer periphery of the case 32, and the lock ring 50 is fixed to the left side of the frame 12 (leg plate 12A). A clutch 48 is arranged inside the lock ring 50, and flat knurled teeth are formed on the inner circumferential surface of the lock ring 50.

[0037] A switching mechanism 52 is provided on the left side of the case 32, and the switching mechanism 52 is connected to the left side of the frame 12 (leg plate 12A).

[0038] The switching mechanism 52 is provided with a pair of gas generators 54, and a supply pipe 56 is connected to the gas generators 54. A circular switching plate 58 is arranged at the outlet of the supply pipe 56, and the switching plate 58 is arranged coaxially with the case 32 and is movable to the right. The diameters of the pair of switching plates 58 are different from each other, and one switching plate 58 is arranged to the left of the left end of one moving rod 40, while the other switching plate 58 is arranged to the left of the left end of the other moving rod 40.

[0039] A biasing mechanism 60 (see FIG. 9) is provided on the left side of the switching mechanism 52, and a power spring (not shown) serving as a biasing member is provided within the biasing mechanism 60. The power spring is connected to the spool 16 via the connecting shaft 34 and the main torsion 22, and biases the spool 16 in the winding direction.

[0040] Next, the operation of this embodiment will be described.

[0041] In the webbing take-up device 10 configured as described above, the webbing 20 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 60, and the webbing 20 is retracted onto the spool 16, thereby removing slack from the webbing 20 attached to the occupant.

[0042] In the event of a vehicle collision, the sensor mechanism is activated and lock plate 28A of pinion 28 meshes with ratchet teeth 14B of cover plate 14 (ratchet hole 14A), restricting rotation of pinion 28 in the pull-out direction and restricting rotation of stopper base 24 in the pull-out direction. As a result, main torsion 22 restricts rotation of spool 16 in the pull-out direction, restricting pull-out of webbing 20 from spool 16, and the occupant is restrained by webbing 20.

[0043] When the pulling load from the spool 16 to the webbing 20 from the occupant (the rotational load of the spool 16 in the unwinding direction) is equal to or exceeds the torsional load resistance of the main torsion 22, the main torsion 22 is torsionally deformed, allowing rotation of the spool 16 in the unwinding direction relative to the pinion 28 and the stopper base 24, whereby the trigger wire 44 is moved to the right within the spool 16 in the operating mechanism 42, and the trigger wire 44 is released from passing through the operating plate 46. Therefore, the biasing force causes the operating plate 46 to rotate in the winding direction relative to the case 32, and the clutch 48 is rotated radially outward from the case 32 by the operating cylinder 46A (circumferential surface of the operating hole 46B) of the operating plate 46, whereby the tip surface (knurled teeth) of the clutch 48 engages (meshes) with the inner circumferential surface (knurled teeth) of the lock ring 50, restricting rotation of the case 32 in the unwinding direction.

[0044] If the occupant is of large build (if the body size sensor detects that the occupant is of large build), the switching mechanism 52 does not activate the pair of gas generators 54 when a vehicle collision is detected, and the left ends of the pair of sub-torsion parts 36 are maintained in mesh with the connecting shaft 34 (connecting gear 34A) (see FIG. 2(A)). Therefore, when the pulling load from the spool 16 to the webbing 20 from the occupant (for example, the load applied to the webbing 20 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 part 22 and the torsional resistance load F2 of the pair of sub-torsion parts 36 (see FIG. 2(B)), the main torsion part 22 and the pair of sub-torsion parts 36 are torsionally deformed, allowing the spool 16 to rotate in the unwinding direction relative to the pinion 28, the stopper base 24, and the case 32, and allowing the webbing 20 to be unwound 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 22 and the pair of sub-torsion 36, thereby providing adequate protection for large occupants.

[0045] If the occupant has a medium build (if the build sensor detects that the occupant has a medium build), in the switching mechanism 52, when a vehicle collision is detected, one gas generator 54 is activated to instantaneously generate high-pressure gas in the supply pipe 56, causing one switching plate 58 to move rightward due to the pressure of the gas, and one sub-torsion 36 is moved rightward against the biasing force of the spring 38 via one moving rod 40 (see FIG. 3(A)). As a result, the state of movement of one sub-torsion 36 to the right is maintained, and the left end of one sub-torsion 36 is released from meshing with the connecting shaft 34 (connecting gear 34A). For this reason, when the pulling load from the spool 16 onto the webbing 20 from the occupant (for example, a load acting on the webbing 20 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 22 and the torsional resistance load F2 of the other sub-torsion 36 (see FIG. 3(B)), the main torsion 22 and the other sub-torsion 36 are torsionally deformed, allowing rotation of the spool 16 in the unwinding direction relative to the pinion 28, the stopper base 24, and the case 32, and allowing unwinding of the webbing 20 from the spool 16. As a result, the force limiter load is set to an intermediate load, and the kinetic energy of the occupant is absorbed by the torsional deformation of the main torsion 22 and the other sub-torsion 36, so that the medium-sized occupant is appropriately protected.

[0046] If the occupant is small in stature (if the physique sensor detects that the occupant is small in stature), in the switching mechanism 52, when a vehicle collision is detected, the pair of gas generators 54 are activated to instantaneously generate high-pressure gas in the supply pipes 56, causing the pressure of the gas to move each switching plate 58 to the right, and the pair of sub-torsion members 36 are moved to the right against the biasing force of the springs 38 via each moving rod 40 (see FIG. 4(A)). As a result, the pair of sub-torsion members 36 are maintained in a state of moving to the right, and the left ends of the pair of sub-torsion members 36 are disengaged from the connecting shaft 34 (connecting gear 34A). For this reason, when the pulling load from the spool 16 onto the webbing 20 from the occupant (for example, a load acting on the webbing 20 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 22 (see FIG. 4(B)), the main torsion 22 is torsionally deformed, allowing rotation of the spool 16 in the unwinding direction relative to the pinion 28, the stopper base 24, and the case 32, and allowing the webbing 20 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 22, thereby appropriately protecting small occupants.

[0047] Here, the main torsion 22 starts to twist (allowing the webbing 20 to be pulled out from the spool 16), and the operating mechanism 42 is actuated by the movement of the trigger wire 44 (restricting the rotation of the case 32 in the pull-out direction). This allows the sub-torsion 36 to operate (torsional deformation) early.

[0048] Furthermore, the switching mechanism 52 switches between meshing and disengaging with the connecting shaft 34 (connecting gear 34A) at the left end of the sub torsion 36, thereby switching between operating and non-operating states of the sub torsion 36. This makes it possible to change the force limiter load (the load that allows the webbing 20 to be pulled out from the spool 16).

[0049] Furthermore, when a vehicle collision is detected when the main torsion 22 starts to twist (or may be before the main torsion 22 begins to twist), the switching mechanism 52 switches the sub-torsion 36 between operating and non-operating. This allows the force limiter load to be adjusted early.

[0050] Furthermore, the sub-torsion 36 is disposed axially outward of the spool 16. Therefore, the sub-torsion 36 can be easily disposed, and the dimension of the webbing take-up device 10 in the radial direction of the spool 16 can be reduced.

[0051] Furthermore, a stopper 26 is fitted between the circumferential surface of the stopper hole 18 of the spool 16 and the connecting cylinder 24A of the stopper base 24. This increases the strength of the portion between the spool 16 and the stopper base 24.

[0052] In this embodiment, in a state in which the force limiter load is set to a high load, at least one gas generator 54 may be activated to stop the torsional deformation of at least one sub-torsion 36 while the webbing 20 is being permitted to be unwound from the spool 16 (see the dashed arrow in FIG. 2(B)). This makes it possible to vary (reduce) the force limiter load while the webbing 20 is being permitted to be unwound from the spool 16.

[0053] Furthermore, in the present embodiment, in a state where the force limiter load is set to a medium load, the other gas generator 54 may be activated to stop the torsional deformation of the other sub-torsion 36 while the webbing 20 is being permitted to be unwound from the spool 16 (see the dashed arrow in FIG. 3(B)). This makes it possible to vary (reduce) the force limiter load while the webbing 20 is being permitted to be unwound from the spool 16.

[0054] [Second embodiment] FIG. 5 shows a cross-sectional view of a webbing take-up device 70 according to a second embodiment of the present invention, as viewed from the front.

[0055] The webbing take-up device 70 according to this embodiment has almost the same configuration as that of the first embodiment, but differs in the following respects.

[0056] 5, in the webbing take-up device 70 according to this embodiment, the case 32 is fixed to the left side of the frame 12 (leg plate 12A), and the inside of the case 32 is open to the right. In addition, a connecting gear 34A is formed on the right portion of the connecting shaft 34.

[0057] The left end of the sub-torsion 36 is non-rotatably supported by the left wall of the case 32, and the sub-torsion 36 is non-movable in the left-right direction. A substantially cylindrical operating gear 72 with a bottom is disposed on the right side of the sub-torsion 36, and the interior of the operating gear 72 is open to the left. The operating gear 72 is movable leftward, and when the operating gear 72 is moved leftward, the right end of the sub-torsion 36 is connected to the operating gear 72 so as to be rotatable therewith, and the connecting gear 34A of the connecting shaft 34 is meshed with the outer periphery of the operating gear 72. A moving plate 72A in the shape of an annular plate is provided integrally with the outer periphery of the operating gear 72, and the moving plate 72A is disposed coaxially with the operating gear 72.

[0058] In the actuating mechanism 42, an actuating plate 46 is coaxially supported on the left end of the main torsion 22, and is biased in the winding direction (or the unwinding direction) relative to the main torsion 22, and is disposed within the case 32. A plurality of approximately rectangular plate-shaped actuating protrusions 46C (see FIG. 6(A)) are integrally provided on the left end of an actuating cylinder 46A of the actuating plate 46, and the plurality of actuating protrusions 46C protrude radially inward from the actuating cylinder 46A and are disposed at equal intervals around the circumference of the actuating cylinder 46A.

[0059] A generally annular biasing plate 74 serving as a biasing portion is coaxially supported on the left side of the actuating plate 46 at the left end of the main torsion 22. The biasing plate 74 is rotatable integrally with the main torsion 22 and movable leftward. A plurality of generally rectangular biasing protrusions 74A are integrally formed on the outer periphery of the biasing plate 74. The biasing protrusions 74A protrude radially outward from the biasing plate 74 and are arranged at equal intervals around the circumferential direction of the biasing plate 74. An actuating protrusion 46C of the actuating plate 46 (actuating cylinder 46A) engages with the biasing protrusions 74A from the left side, thereby preventing the biasing plate 74 from moving leftward, and the biasing plate 74 is disposed to the right of the actuating gear 72. A plurality of springs 38 (compression coil springs) are stretched between the biasing plate 74 and the actuating plate 46. The springs 38 bias the biasing plate 74 leftward.

[0060] Incidentally, in the event of a vehicle collision, when rotation of the pinion 28 and the stopper base 24 in the unwinding direction is restricted and the pulling load from the spool 16 to the webbing 20 from the occupant (rotational load in the unwinding direction of the spool 16) is equal to or exceeds the torsional load resistance of the main torsion 22, the main torsion 22 is torsionally deformed and rotation of the spool 16 in the unwinding direction relative to the pinion 28 and the stopper base 24 is permitted, so that in the operating mechanism 42, the trigger wire 44 is moved to the right within the spool 16 and the trigger wire 44 is released from passing through the operating plate 46. Therefore, the biasing force of the operating plate 46 rotates in the winding direction relative to the main torsion 22, and the engagement of the operating protrusion 46C of the operating plate 46 (operating cylinder 46A) with the biasing protrusion 74A of the biasing plate 74 is released, so that the biasing plate 74 is moved leftward by the biasing force of the spring 38, and the pair of operating gears 72 are moved leftward by the biasing plate 74. As a result, the right ends of the pair of sub-torsion members 36 are connected to the pair of operating gears 72 so as to be able to rotate together, and the connecting gear 34A of the connecting shaft 34 is meshed with the outer periphery of the pair of operating gears 72, so that the right ends of the pair of sub-torsion members 36 are connected to the connecting shaft 34 (connecting gear 34A) via the pair of operating gears 72.

[0061] If the occupant is of large build (if the body size sensor detects that the occupant is of large build), the switching mechanism 52 does not activate the pair of gas generators 54 when a vehicle collision is detected, and communication with the connecting shaft 34 (connecting gear 34A) at the right end of the pair of sub-torsion parts 36 is maintained (see FIG. 6(A)). Therefore, when the pulling load from the spool 16 to the webbing 20 from the occupant (for example, the load acting on the webbing 20 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 part 22 and the torsional resistance load F2 of the pair of sub-torsion parts 36 (see FIG. 6(B)), the main torsion part 22 and the pair of sub-torsion parts 36 are torsionally deformed, allowing rotation of the spool 16 in the unwinding direction relative to the pinion 28 and the stopper base 24, and allowing the webbing 20 to be unwound 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 22 and the pair of sub-torsion 36, thereby providing adequate protection for large occupants.

[0062] If the occupant has a medium build (if the build sensor detects that the occupant has a medium build), in the switching mechanism 52, when a vehicle collision is detected, one gas generator 54 is activated to instantaneously generate high-pressure gas in the supply pipe 56, and the pressure of the gas moves one moving plate 72A to the right, and one operating gear 72 and biasing plate 74 are moved to the right against the biasing force of the spring 38 (see FIG. 7(A)). As a result, the state in which one operating gear 72 and biasing plate 74 are moved to the right is maintained, and the connection of the right end of one sub-torsion 36 to the connecting shaft 34 (connecting gear 34A) is released. For this reason, when the pulling load from the spool 16 onto the webbing 20 from the occupant (for example, a load acting on the webbing 20 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 22 and the torsional resistance load F2 of the other sub-torsion 36 (see FIG. 7(B)), the main torsion 22 and the other sub-torsion 36 are torsionally deformed, allowing rotation of the spool 16 in the unwinding direction relative to the pinion 28 and the stopper base 24 and allowing unwinding of the webbing 20 from the spool 16. As a result, the force limiter load is set to an intermediate load, and the kinetic energy of the occupant is absorbed by the torsional deformation of the main torsion 22 and the other sub-torsion 36, so that the medium-sized occupant is appropriately protected.

[0063] If the occupant is small in stature (if the physique sensor detects that the occupant is small in stature), in the switching mechanism 52, when a vehicle collision is detected, the pair of gas generators 54 are activated to instantaneously generate high-pressure gas in the supply pipe 56, and the pressure of the gas moves each moving plate 72A to the right, and the pair of operating gears 72 and the biasing plate 74 are moved to the right against the biasing force of the spring 38 (see FIG. 8(A)). As a result, the pair of operating gears 72 and the biasing plate 74 are maintained in their rightward movement state, and the connection of the right ends of the pair of sub-torsion springs 36 to the connecting shaft 34 (connecting gear 34A) is released. For this reason, when the pulling load from the spool 16 onto the webbing 20 from the occupant (for example, a load acting on the webbing 20 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 22 (see FIG. 8(B)), the main torsion 22 is torsionally deformed, allowing rotation of the spool 16 in the unwinding direction relative to the pinion 28 and the stopper base 24 and allowing unwinding of the webbing 20 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 22, thereby appropriately protecting small occupants.

[0064] Here, this embodiment can also achieve the same functions and effects as the first embodiment.

[0065] In this embodiment, in a state in which the force limiter load is set to a high load, at least one gas generator 54 may be activated to stop the torsional deformation of at least one sub-torsion 36 while the webbing 20 is being permitted to be unwound from the spool 16 (see the dashed arrow in FIG. 6(B)). This makes it possible to vary (reduce) the force limiter load while the webbing 20 is being permitted to be unwound from the spool 16.

[0066] Furthermore, in the present embodiment, in a state where the force limiter load is set to a medium load, the other gas generator 54 may be activated to stop the torsional deformation of the other sub-torsion 36 while the webbing 20 is being permitted to be unwound from the spool 16 (see the dashed arrow in FIG. 7(B)). This makes it possible to vary (reduce) the force limiter load while the webbing 20 is being permitted to be unwound from the spool 16.

[0067] [Third embodiment] FIG. 9 shows a cross-sectional view of a webbing take-up device 80 according to a third embodiment of the present invention, as viewed from the front.

[0068] The webbing take-up device 80 according to this embodiment has substantially the same configuration as that of the first embodiment, but differs in the following respects.

[0069] As shown in FIG. 9, in a webbing take-up device 80 according to this embodiment, the pinion 28 passes coaxially through the stopper base 24, and the connecting tube 24A is provided on the pinion 28 instead of the stopper base 24.

[0070] No case 32 is provided on the left side of the frame 12 (leg plate 12A). The operating plate 46 is biased in the winding direction (or the unwinding direction) relative to the connecting shaft 34, and a clutch 48 is supported on the outer periphery of the expanded diameter portion of the connecting shaft 34. The left end of the main torsion 22 protrudes to the left of the connecting shaft 34, and a power spring of the biasing mechanism 60 is connected to the left end of the main torsion 22.

[0071] A lock ring 50 is rotatably supported on the left side of the frame 12 (leg plate 12A). The lock ring 50 is arranged coaxially with the connecting shaft 34, and a clutch 48 is arranged inside the lock ring 50.

[0072] A generally bottomed, cylindrical operating gear 72 is supported on the leg plate 12A of the frame 12 above and below the lock ring 50, and the right portion of the operating gear 72 penetrates and fits into the leg plate 12A, allowing it to rotate. The left portion of the operating gear 72 meshes with the outer periphery of the lock ring 50, and the interior of the operating gear 72 is open to the right. A generally cylindrical support tube 82 is fitted into the right portion of the operating gear 72, and the support tube 82 extends in the left-right direction. The support tube 82 is fixed to the leg plate 12B of the frame 12, preventing it from rotating.

[0073] The sub-torsion 36 is arranged coaxially within the support cylinder 82, and the right end of the sub-torsion 36 is supported by the support cylinder 82 so as to be non-rotatable but movable to the right. A spring 38 (compression coil spring) is hung between the right end of the sub-torsion 36 and the leg plate 12B of the frame 12, and the sub-torsion 36 is urged leftward by the spring 38. The left end of the sub-torsion 36 is supported by the left part of the operating gear 72 so as to be rotatable integrally therewith, and the left end of the sub-torsion 36 is exposed to the left side of the operating gear 72.

[0074] A substantially cylindrical moving rod 40 is arranged coaxially to the left of the sub-torsion 36 , and the moving rod 40 is arranged at the discharge port of the supply pipe 56 in the switching mechanism 52 .

[0075] Incidentally, in the event of a vehicle collision, rotation of the pinion 28 and the stopper base 24 in the pull-out direction is restricted, and when the pulling load from the spool 16 from the occupant to the webbing 20 (rotational load in the pull-out direction of the spool 16) is greater than the torsional load capacity of the main torsion 22, the main torsion 22 is torsionally deformed, and rotation of the spool 16 in the pull-out direction relative to the pinion 28 and the stopper base 24 is permitted, and in the operating mechanism 42, the trigger wire 44 is moved to the right within the spool 16, and the trigger wire 44 is released from passing through the operating plate 46. As a result, the actuating plate 46 is rotated in the winding direction relative to the connecting shaft 34 by the urging force, and the clutch 48 is rotated radially outward of the connecting shaft 34 by the actuating cylinder 46A (circumferential surface of the actuating hole 46B) of the actuating plate 46, causing the tip surface (knurled teeth) of the clutch 48 to engage (mesh) with the inner peripheral surface (knurled teeth) of the lock ring 50, allowing the lock ring 50 to rotate integrally with the connecting shaft 34 in the pull-out direction.

[0076] If the occupant is of large build (if the body size sensor detects that the occupant is of large build), the switching mechanism 52 does not activate the pair of gas generators 54 when a vehicle collision is detected, and the connection of the left ends of the pair of sub-torsion parts 36 to the operating gears 72 is maintained (see FIG. 10(A)). Therefore, when the pulling load from the spool 16 to the webbing 20 from the occupant (for example, the load acting on the webbing 20 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 part 22 and the torsional resistance load F2 of the pair of sub-torsion parts 36 (see FIG. 10(B)), the main torsion part 22 and the pair of sub-torsion parts 36 are torsionally deformed, thereby allowing the spool 16 to rotate in the unwinding direction relative to the pinion 28 and the stopper base 24, and allowing the webbing 20 to be unwound 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 22 and the pair of sub-torsion 36, thereby providing adequate protection for large occupants.

[0077] If the occupant has a medium build (if the build sensor detects that the occupant has a medium build), in the switching mechanism 52, when a vehicle collision is detected, one of the gas generators 54 is activated to instantaneously generate high-pressure gas in the supply pipe 56, and the pressure of the gas moves one of the moving rods 40 to the right, and one of the sub-torsion members 36 moves to the right against the biasing force of the spring 38 (see FIG. 11(A)). As a result, the state of movement of one of the sub-torsion members 36 to the right is maintained, and the connection of the left end of one of the sub-torsion members 36 to the operating gear 72 is released. For this reason, when the pulling load from the spool 16 onto the webbing 20 from the occupant (for example, a load acting on the webbing 20 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 22 and the torsional resistance load F2 of the other sub-torsion 36 (see FIG. 11(B)), the main torsion 22 and the other sub-torsion 36 are torsionally deformed, allowing rotation of the spool 16 in the unwinding direction relative to the pinion 28 and the stopper base 24 and allowing unwinding of the webbing 20 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 22 and the other sub-torsion 36, so that the medium-sized occupant is appropriately protected.

[0078] If the occupant is small in stature (if the physique sensor detects that the occupant is small in stature), in the switching mechanism 52, when a vehicle collision is detected, the pair of gas generators 54 are activated to instantaneously generate high-pressure gas in the supply pipes 56, and the pressure of the gas moves each moving rod 40 to the right, and the pair of sub-torsion members 36 are moved to the right against the biasing force of the springs 38 (see FIG. 12(A)). As a result, the pair of sub-torsion members 36 are maintained in a state of moving to the right, and the connection of the left ends of the pair of sub-torsion members 36 to the operating gear 72 is released. For this reason, when the pulling load from the spool 16 onto the webbing 20 from the occupant (for example, a load acting on the webbing 20 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 22 (see FIG. 12(B)), the main torsion 22 is torsionally deformed, allowing rotation of the spool 16 in the unwinding direction relative to the pinion 28 and the stopper base 24 and allowing unwinding of the webbing 20 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 22, thereby appropriately protecting small occupants.

[0079] Here, in this embodiment as well, except for the effects and advantages resulting from the sub torsion 36 being disposed axially outward of the spool 16, the same effects and advantages as in the first embodiment can be achieved.

[0080] Furthermore, the sub-torsion 36 is disposed radially outward of the spool 16. Therefore, the sub-torsion 36 can be easily disposed, and the dimension of the webbing take-up device 80 in the axial direction of the spool 16 can be reduced.

[0081] In this embodiment, in a state in which the force limiter load is set to a high load, at least one gas generator 54 may be activated to stop the torsional deformation of at least one sub-torsion 36 while the webbing 20 is being permitted to be unwound from the spool 16 (see the dashed arrow in FIG. 10(B)). This makes it possible to vary (reduce) the force limiter load while the webbing 20 is being permitted to be unwound from the spool 16.

[0082] Furthermore, in the present embodiment, in a state where the force limiter load is set to a medium load, the other gas generator 54 may be activated to stop the torsional deformation of the other sub-torsion 36 while the webbing 20 is being permitted to be unwound from the spool 16 (see the dashed arrow in FIG. 11(B)). This makes it possible to vary (reduce) the force limiter load while the webbing 20 is being permitted to be unwound from the spool 16.

[0083] In the first to third embodiments, the pair of sub-torsion members 36 have the same torsional load resistance. However, the torsional load resistance of one of the sub-torsion members 36 may be smaller or larger than the torsional load resistance of the other sub-torsion member 36.

[0084] Furthermore, in the first to third embodiments, the torsional load resistance of the sub-torsion 36 is set smaller than the torsional load resistance of the main torsion 22. However, the torsional load resistance of the sub-torsion 36 may be set equal to or greater than the torsional load resistance of the main torsion 22.

[0085] [Fourth embodiment] FIG. 13 shows a cross-sectional view of a webbing take-up device 90 according to a third embodiment of the present invention, as viewed from the front.

[0086] The webbing take-up device 90 according to this embodiment has substantially the same configuration as that of the third embodiment, but differs in the following respects.

[0087] As shown in FIG. 13, a webbing take-up device 90 according to this embodiment does not include one (upper) operating gear 72, support cylinder 82, spring 38, and moving rod 40 in the third embodiment.

[0088] The left end of the main torsion 22 is connected to an axially intermediate portion of the spool 16 so as to be integrally rotatable, and the right portion of the connecting shaft 34 is rotatably supported within the spool 16. One of the sub-torsion 36 (hereinafter referred to as the "first sub-torsion 36A") is disposed coaxially with the main torsion 22, and its right end is connected to an axially intermediate portion of the spool 16 so as to be integrally rotatable, and the left end of the first sub-torsion 36A is connected to the connecting shaft 34 so as to be integrally rotatable. The torsional load resistance of the first sub-torsion 36A is greater than the torsional load resistance of the other (lower) sub-torsion 36 (hereinafter referred to as the "second sub-torsion 36B") and is set to be the same as the torsional load resistance of the main torsion 22. In addition, a spiral spring of the biasing mechanism 60 is connected to the connecting shaft 34.

[0089] A pawl 92 serving as a fixed member is disposed at the discharge port of one (upper) supply pipe 56 of the switching mechanism 52, and the pawl 92 is supported by the leg plate 12A of the frame 12. The pawl 92 is held in a state in which it is engaged with the outer periphery of the lock ring 50, and the pawl 92 restricts the rotation of the lock ring 50.

[0090] Incidentally, in the event of a vehicle collision, rotation of the pinion 28 and the stopper base 24 in the pull-out direction is restricted, and when the pulling load from the spool 16 from the occupant to the webbing 20 (rotational load in the pull-out direction of the spool 16) is greater than the torsional load capacity of the main torsion 22, the main torsion 22 is torsionally deformed, and rotation of the spool 16 in the pull-out direction relative to the pinion 28 and the stopper base 24 is permitted, and in the operating mechanism 42, the trigger wire 44 is moved to the right within the spool 16, and the trigger wire 44 is released from passing through the operating plate 46. As a result, the actuating plate 46 is rotated in the winding direction relative to the connecting shaft 34 by the urging force, and the clutch 48 is rotated radially outward of the connecting shaft 34 by the actuating cylinder 46A (circumferential surface of the actuating hole 46B) of the actuating plate 46, causing the tip surface (knurled teeth) of the clutch 48 to engage (mesh) with the inner surface (knurled teeth) of the lock ring 50, and the lock ring 50 restricts the rotation of the connecting shaft 34 and the left end of the first sub-torsion 36A in the pull-out direction.

[0091] If the occupant is of large build (if the build sensor detects that the occupant is of large build), the pair of gas generators 54 are not activated when a vehicle collision is detected in the switching mechanism 52, and the restriction on rotation of the connecting shaft 34 and the left end of the first sub-torsion 36A in the pull-out direction and the connection of the left end of the second sub-torsion 36B to the operating gear 72 are maintained (see Figure 14(A)). For this reason, when the pulling load from the spool 16 onto the webbing 20 from the occupant (for example, a load acting on the webbing 20 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 22 and the torsional resistance load F3 of the first sub-torsion 36A (see FIG. 14(B)), the main torsion 22 and the first sub-torsion 36A are torsionally deformed, allowing rotation of the spool 16 in the unwinding direction relative to the pinion 28 and the stopper base 24 and allowing unwinding of the webbing 20 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 22 and the first sub-torsion 36A, so that large occupants are appropriately protected.

[0092] If the occupant is of medium build (if the build sensor detects that the occupant is of medium build), in the switching mechanism 52, when a vehicle collision is detected, one of the gas generators 54 is activated to instantaneously generate high-pressure gas in the supply pipe 56, and the pressure of the gas releases the hold on the pawl 92, thereby releasing the restriction on rotation of the lock ring 50 by the pawl 92 (see FIG. 15(A)). This allows the lock ring 50, connecting shaft 34, and first sub-torsion 36A to rotate integrally with the spool 16 in the pull-out direction. For this reason, when the pulling load from the spool 16 onto the webbing 20 from the occupant (for example, a load acting on the webbing 20 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 22 and the torsional resistance load F2 of the second sub-torsion 36B (see FIG. 15(B)), the main torsion 22 and the second sub-torsion 36B are torsionally deformed, allowing rotation of the spool 16 in the unwinding direction relative to the pinion 28 and the stopper base 24 and allowing unwinding of the webbing 20 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 22 and the second sub-torsion 36B, so that the medium-sized occupant is appropriately protected.

[0093] If the occupant is small in stature (if the physique sensor detects that the occupant is small in stature), in the switching mechanism 52, when a vehicle collision is detected, the pair of gas generators 54 is activated to instantaneously generate high-pressure gas in the supply pipe 56, whereby the gas pressure from one of the gas generators 54 releases the hold of the pawl 92, releasing the restriction on rotation of the lock ring 50 by the pawl 92, and the gas pressure from the other gas generator 54 moves the moving rod 40 to the right, moving the second sub-torsion 36B to the right against the biasing force of the spring 38 (see FIG. 16(A)). As a result, the lock ring 50, connecting shaft 34, and first sub-torsion 36A become rotatable integrally with the spool 16 in the pull-out direction, and the second sub-torsion 36B is maintained in its rightward movement state, releasing the connection of the left end of the second sub-torsion 36B to the operating gear 72. For this reason, when the pulling load from the spool 16 onto the webbing 20 from the occupant (for example, a load acting on the webbing 20 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 22 (see FIG. 16(B)), the main torsion 22 is torsionally deformed, allowing rotation of the spool 16 in the unwinding direction relative to the pinion 28 and the stopper base 24 and allowing unwinding of the webbing 20 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 22, thereby appropriately protecting small occupants.

[0094] Here, this embodiment can also achieve the same functions and effects as the third embodiment.

[0095] In particular, the first sub-torsion 36A is disposed inside the spool 16, and the second sub-torsion 36B is disposed radially outside the spool 16. Therefore, the second sub-torsion 36B can be easily disposed, and the dimension of the webbing take-up device 90 in the axial direction of the spool 16 can be reduced.

[0096] In this embodiment, in a state in which the force limiter load is set to a high load, one or both of the gas generators 54 may be activated to stop the torsional deformation of the first sub-torsion 36A or the torsional deformation of the first sub-torsion 36A and the second sub-torsion 36B while the webbing 20 is being permitted to be unwound from the spool 16 (see the dashed arrows in FIG. 14(B)). This makes it possible to vary (reduce) the force limiter load while the webbing 20 is being permitted to be unwound from the spool 16.

[0097] Furthermore, in the present embodiment, in a state where the force limiter load is set to a medium load, the other gas generator 54 may be activated to stop the torsional deformation of the second sub-torsion 36B while the webbing 20 is being permitted to be unwound from the spool 16 (see the dashed arrow in FIG. 15(B)). This makes it possible to vary (reduce) the force limiter load while the webbing 20 is being permitted to be unwound from the spool 16.

[0098] In this embodiment, the torsional load resistance of the first sub-torsion 36A is set to be the same as the torsional load resistance of the main torsion 22. However, the torsional load resistance of the first sub-torsion 36A may be set to be smaller or larger than the torsional load resistance of the main torsion 22.

[0099] Furthermore, in this embodiment, the torsional load resistance of the second sub-torsion 36B is set smaller than the torsional load resistance of the main torsion 22. However, the torsional load resistance of the second sub-torsion 36B may be set equal to or larger than the torsional load resistance of the main torsion 22. [Explanation of symbols]

[0100] 10 webbing take-up device, 16 spool, 20 webbing, 22 main torsion (first member), 24 stopper base (regulating body), 28 pinion (regulating body), 36 sub-torsion (second member), 36A first sub-torsion (second member), 36B second sub-torsion (second member), 42 operating mechanism, 52 switching mechanism, 70 webbing take-up device, 80 webbing take-up device, 90 webbing take-up device

Claims

1. a spool around which a webbing to be worn by an occupant is wound and which rotates in the unwinding direction to unwind the webbing; a restricting body that can restrict rotation in the pull-out direction; a first member connected to the spool and the restrictor, which is torsionally deformed when rotation of the restrictor in the pull-out direction is restricted, thereby allowing rotation of the spool in the pull-out direction; an actuation mechanism that is actuated when the torsional deformation of the first member is initiated; a plurality of second members, at least one of which is disposed at a position not coaxial with the first member, and which are torsionally deformed when the actuation mechanism is actuated, thereby allowing rotation of the spool in the pull-out direction; A webbing take-up device comprising:

2. The webbing take-up device according to claim 1, further comprising a switching mechanism that switches between an operation state and an inoperation state of the second member.

3. The webbing take-up device according to claim 2, wherein the switching mechanism switches between operating and inoperating the second member before or when the first member is torsionally deformed.

4. The webbing take-up device according to claim 1 , wherein the second member is disposed axially outward of the spool.

5. The webbing take-up device according to claim 1 , wherein the second member is disposed radially outward of the spool.

Images