Load-limiting seat belt retractor

Abstract

A seat belt retractor includes a housing and a spool rotatably supported by the housing. A torsion bar has a first end and a second end. The first end of the torsion bar is fixed to the spool, and the second end of the torsion bar is fixable relative to the housing. The seat belt retractor includes a magnet and a rotor disposed adjacent to the magnet. One of the magnet and the rotor is fixed relative to the spool, and the other of the magnet and the rotor rotates relative to the spool. The rotor includes a conductive material.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicles, and more particularly to a load-limiting seat belt retractor. Background Art

[0002] Seat belts in vehicles can be equipped with a "load-limiting" feature. During a collision, the retractor of the seat belt can lock the webbing of the seat belt from further extending from the retractor, but when the force applied to the webbing exceeds the load limit threshold, the load-limiting feature allows some additional limited extension of the webbing. This additional extension of the webbing from the retractor limits the load applied by the webbing to the occupant's chest to reduce chest deflection.

[0003] Load limitation can be achieved by using a torsion bar. The retractor includes a housing and a spool rotatable relative to the housing. One end of the torsion bar can be connected to the spool, and the webbing is wound around the spool in the retractor. When the torsion bar is not engaged, both the torsion bar and the spool rotate relative to the housing when the webbing is pulled out of / retracted into the retractor. In the event of a collision, the other end of the torsion bar can be fixed relative to the housing of the retractor. When an occupant applies a force tending to extract the webbing from the retractor, the spool applies a torsional force to the torsion bar. The torsion bar yields, i.e., deforms, at a known threshold force. Thus, the force imparted to the occupant by the seat belt is limited by the threshold force of the torsion bar. Summary of the Invention

[0004] According to the present invention, there is provided a seat belt retractor, comprising:

[0005] A housing;

[0006] A spool rotatably supported by the housing;

[0007] A torsion bar having a first end and a second end, the first end being fixed to the spool and the second end being fixable relative to the housing;

[0008] A magnet and a rotor, the rotor being disposed near the magnet, one of the magnet and the rotor being fixed relative to the spool and the other of the magnet and the rotor being rotatable relative to the spool, the rotor including a conductive material.

[0009] According to an embodiment of the present invention, the seat belt retractor further comprises a plurality of magnets, and the magnets are spaced apart from each other along the torsion bar.

[0010] According to an embodiment of the present invention, the magnets each extend circumferentially from the torsion bar.

[0011] According to an embodiment of the present invention, the rotor is disposed between the magnets.

[0012] According to an embodiment of the present invention, the rotor extends circumferentially from the torsion bar.

[0013] According to one embodiment of the present invention, the seat belt retractor further includes a plurality of magnets, and the magnets are circumferentially spaced apart from each other with respect to the torsion bar.

[0014] According to one embodiment of the present invention, the rotor extends around the magnet with respect to the torsion bar.

[0015] According to one embodiment of the present invention, the rotor is fixed to the spool.

[0016] According to one embodiment of the present invention, the seat belt retractor further includes a plate, the plate includes a plurality of notches circumferentially spaced apart from each other with respect to the torsion bar, and one magnet is disposed in each notch.

[0017] According to one embodiment of the present invention, the spool includes a first end and a second end spaced apart from each other along an axis.

[0018] According to one embodiment of the present invention, the torsion bar and the spool extend coaxially from the respective first ends to the respective second ends.

[0019] According to one embodiment of the present invention, the first end of the torsion bar is fixed to the first end of the spool.

[0020] According to one embodiment of the present invention, the magnet is disposed between the first end and the second end of the spool.

[0021] According to one embodiment of the present invention, the first end of the torsion bar extends outward from the first end of the spool.

[0022] According to one embodiment of the present invention, the first end of the spool is disposed between the second end of the spool and the magnet.

[0023] According to one embodiment of the present invention, the spool defines a cavity extending circumferentially with respect to the axis.

[0024] According to one embodiment of the present invention, the magnet is disposed in the cavity.

[0025] According to one embodiment of the present invention, the spool includes a groove extending circumferentially with respect to the axis, and the magnet is disposed in the groove.

[0026] A seat belt retractor, the seat belt retractor further includes a webbing having an end, and the end of the webbing is attached to the spool. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a perspective view of a vehicle seat having a restraint system in a vehicle;

[0028] Figure 2Is a perspective view of a part of a restraint system including a seat belt retractor and a webbing engaged with the seat belt retractor;

[0029] Figure 3 Is an exploded view of the seat belt retractor of the restraint system;

[0030] Figure 4 Is a perspective view of an embodiment of the seat belt retractor;

[0031] Figure 5 Is a perspective view of another embodiment of the seat belt retractor;

[0032] Figure 6 Is a perspective view of another embodiment of the seat belt retractor;

[0033] Figure 7 Is a perspective view of another embodiment of the seat belt retractor. Detailed Description

[0034] The seat belt retractor includes a housing and a spool rotatably supported by the housing. The torsion bar has a first end and a second end. The first end is fixed to the spool, and the second end is fixable relative to the housing. The seat belt retractor includes a magnet and a rotor disposed adjacent to the magnet. One of the magnet and the rotor is fixed relative to the spool, and the other of the magnet and the rotor is rotatable relative to the spool. The rotor includes a conductive material.

[0035] The seat belt retractor may include a plurality of magnets. The magnets may be spaced apart from each other along the torsion bar. Each magnet may extend circumferentially from the torsion bar. The rotor may be disposed between the magnets. The rotor may extend circumferentially from the torsion bar.

[0036] The magnets may be circumferentially spaced apart from each other about the torsion bar. The rotor may extend about the torsion bar around the magnets. The rotor may be fixed to the spool.

[0037] The seat belt retractor may include a plate supported by the torsion bar, and the plate includes a plurality of notches circumferentially spaced apart from each other about the torsion bar. One magnet may be disposed in each notch.

[0038] The spool may include a first end and a second end spaced apart from each other along an axis. The spool and the torsion bar may coaxially extend from the respective first ends to the respective second ends. The first end of the torsion bar may be connected to the first end of the spool. The magnet may be disposed between the first end and the second end of the spool. The first end of the torsion bar may extend outwardly from the first end of the spool. The first end of the spool may be disposed between the second end of the spool and the magnet.

[0039] The spool may define a cavity extending circumferentially about the axis. The magnet may be disposed in the cavity.

[0040] The spool may include a groove extending circumferentially about an axis. The magnet may be disposed in the groove.

[0041] The seat belt retractor may include a webbing having ends. The ends of the webbing may be attached to the spool.

[0042] Referring to the accompanying drawings, in which like reference numerals refer to like parts throughout the several views, vehicle 10 is generally shown. Vehicle 10 includes a seat 12 and a restraint system 14 having a seat belt retractor 16 and a webbing 18 that engages seat belt retractor 16. During a vehicle collision, the momentum of an occupant biases the occupant relative to seat 12. For example, in a frontal or oblique collision, the momentum of the occupant may cause the occupant to be displaced from seat 12. As the occupant moves away from seat 12, restraint system 14 (e.g., webbing 18) may apply a force F to the occupant to hold the occupant in seat 12. During a vehicle collision, seat belt retractor 16 may apply a resistance force Fd that counteracts the force applied by webbing 18 in order to allow load limiting as webbing 18 holds the occupant in seat 12. Specifically, seat belt retractor 16 may apply resistance force Fd to control the payout of webbing 18 during high loads to reduce chest compression of the occupant during a vehicle collision. In this case, seat belt retractor 16 may absorb energy to reduce the force applied by webbing 18 to the occupant's chest during a vehicle collision.

[0043] Reference Figure 2 and 3 Referring to FIGS. 11 and 12, seat belt retractor 16 includes a housing 20 and a spool 22 rotatably supported by housing 20. Seat belt retractor 16 includes a torsion bar 24 having a first end 26 and a second end 28. The first end 26 of torsion bar 24 is fixed to spool 22 and the second end 28 of torsion bar 24 is fixed relative to housing 20. Seat belt retractor 16 includes a magnet 30 and a rotor 32 disposed adjacent magnet 30. One of magnet 30 and rotor 32 is fixed relative to spool 22 and the other of magnet 30 and rotor 32 is rotatable relative to spool 22. Rotor 32 includes a conductive material.

[0044] During a vehicle collision, the seatbelt retractor 16 is in a locked position and prevents the second end 28 of the torsion bar 24 from rotating relative to the housing 20, as further described below. In this case, when an occupant applies a force to the webbing 18 during a vehicle collision, the first end 26 of the torsion bar 24 rotates relative to the second end 28 of the torsion bar 24. When the first end 26 of the torsion bar 24 rotates relative to the second end 28 of the torsion bar 24, the magnet 30 and the rotor 32 rotate relative to each other. By allowing one of the magnet 30 and the rotor 32 to rotate relative to the other of the magnet 30 and the rotor 32, the seatbelt retractor 16 applies a resistance force Fd to help reduce the force F applied by the webbing 18 and reduce the chest compression of the occupant during a vehicle collision.

[0045] Reference Figure 1 , the vehicle 10 can be, for example, any suitable type of motor vehicle. The vehicle 10 can include a vehicle body 34 that defines a passenger compartment 36 to accommodate the occupants (if any) of the vehicle 10. The vehicle body 34 can include a floor and a plurality of pillars 38, 40 that extend in an upward direction from the floor. For example, the pillars 38, 40 can include an A-pillar 38 and a B-pillar 40 spaced apart from the A-pillar 38. The pillars 38, 40 can include additional pillars, such as a C-pillar (not shown).

[0046] Continuing reference Figure 1 , one or more seats 12 can be provided in the front portion of the passenger compartment 36, for example, between the A-pillar 38 and the B-pillar 40. In this case, the seat 12 can be a front seat. The passenger compartment 36 can include one or more rear seats (not shown) provided behind the front seat. The passenger compartment 36 can also include a third row seat (not shown) at the rear (not numbered) of the passenger compartment 36. In this case, instead of or in addition to the front seat, the seat 12 can be a second row seat (not numbered). As Figure 1 shown, the seat 12 is a bucket seat, but the seat 12 can be other suitable types of seats, such as a bench seat.

[0047] As Figure 2 shown, the restraint system 14 can include a seatbelt retractor 16 and a webbing 18 that can be retractably pulled out from the seatbelt retractor 16. The restraint system 14 can include an anchor 42 connected to the webbing 18 and a clip 44 that engages a buckle 46. The restraint system 14 can be provided near the seat 12. For example, the restraint system 14 is adjacent to the front seat 12, as Figure 1 shown. The restraint system 14 holds the occupant on the seat 12 when fastened, for example, during a sudden deceleration of the vehicle 10.

[0048] The anchor 42 attaches one end of the webbing 18 to the seat 12. The other end of the webbing 18 is fed into the seat belt retractor 16. The clip 44 slides freely along the webbing 18 and, when engaged with the buckle 46, divides the webbing 18 into a lap belt and a shoulder belt.

[0049] The restraint system 14 can be a three-point seat belt, which means that the webbing 18 is attached at three points around the occupant when fastened: the anchor 42, the seat belt retractor 16, and the buckle 46. The restraint system 14 can alternatively include another arrangement of attachment points.

[0050] Reference Figure 2 , the housing 20 can include a housing body 48 and a housing cover 50 attached to the housing body 48. The housing 20 can be formed of metal or plastic. The webbing guide 52 can be attached to the housing 20. The housing 20 can be mounted to the vehicle body 34. For example, the housing 20 can be attached to the B-pillar 40, as Figure 1 shown. As another example, when the restraint system 14 is adjacent to a rear seat, the housing 20 can be attached to the C-pillar. Alternatively, the housing 20 can be attached to the seat 12. The housing 20 can be attached to the vehicle body 34 in any suitable manner (e.g., fasteners).

[0051] The seat belt retractor 16 can move from an unlocked position to a locked position. In the unlocked position, the spool 22 rotates freely within the housing 20 to allow the webbing 18 to extend from and retract into the seat belt retractor 16. In the unlocked position, the torsion bar 24 can rotate with the spool 22. In this locked position, the second end 60 of the spool 22 is rotationally locked relative to the housing 20, which prevents the webbing 18 from extending from the seat belt retractor 16 to limit forward movement of the occupant. In this case, the second end 28 of the torsion bar 24 is fixed relative to the housing 20, as described above. The seat belt retractor 16 can be default in the unlocked position, i.e., without a sudden deceleration. During a sudden deceleration of the vehicle 10, the seat belt retractor 16 can change from the unlocked position to the locked position, i.e., the deceleration triggers the components of the seat belt retractor 16 to change from the unlocked position to the locked position.

[0052] The seat belt retractor 16 can include a locking device (not numbered) for fixing the second end 28 of the torsion bar 24, i.e., the spool 22, relative to the housing 20. The locking device can include a ratchet 54 and a pawl 56 engageable with the ratchet 54. For example, the second end 28 of the torsion bar 24 can be attached to the ratchet 54 and the pawl 56.

[0053] Reference Figure 3, the ratchet 54 includes a plurality of teeth that are circumferentially aligned around the ratchet 54 and extend radially therefrom. Each tooth includes a first side (not labeled) and a second side (not labeled), where the first side has a shallower angle relative to the circumference of the ratchet 54 than the second side. When the ratchet 54 rotates relative to the pawl 56 such that the first side of the tooth is presented to the pawl 56, the pawl 56 slides over the tooth, and when the ratchet 54 rotates relative to the pawl 56 such that the second side of the tooth is presented to the pawl 56, the pawl 56 catches on the second side and prevents rotation of the ratchet 54.

[0054] Continuing with reference Figure 3 , the pawl 56 is pivotally connected to the housing 20. The pawl 56 is movable between a disengaged position spaced from the ratchet 54 and an engaged position engaging the ratchet 54. The pawl 56 has a pivot end and a free end. In the disengaged position, the free end is spaced from the ratchet 54. In the engaged position, the free end contacts the ratchet 54.

[0055] The seat belt retractor 16 may include an activation sensor (not shown) that senses a sudden deceleration of the vehicle 10 and triggers activation of a locking device (e.g., the ratchet 54 and the pawl 56) to engage the second end 28 of the torsion bar 24. The activation sensor may communicate with the pawl 56 directly or indirectly through a controller (not shown). The activation sensor may be in the seat belt retractor 16 or elsewhere in the vehicle 10. In the seat belt retractor 16, the activation sensor may be, for example, a weighted pendulum, a centrifugal clutch, or any other suitable type. Outside the seat belt retractor 16 in the vehicle 10, the activation sensor may be, for example, a rear contact sensor such as an accelerometer, a pressure sensor, and a contact switch; a pre-crash sensor such as radar, lidar, and a vision sensing system; or any other suitable type. The vision system may include one or more cameras, a CCD (charge-coupled device) image sensor, a CMOS (complementary metal-oxide semiconductor) image sensor, etc.

[0056] As further elaborated below, several embodiments of the seat belt retractor 16 are shown respectively in Figures 4 to 7 each of. Each embodiment may include any suitable number of magnets 30, i.e., one or more. For example, Figures 4 to 7 each of the embodiments shown in Figure 4 includes a plurality of magnets 30, i.e., more than one. Specifically, in the embodiment shown in Figure 5 , the magnets 30 may be spaced apart from each other along the torsion bar 24 and surrounded by the spool 22. In the embodiment shown in Figure 6 , the magnets 30 may be spaced apart from each other along the torsion bar 22 and spaced from the spool 22. In the embodiment shown in Figure 7In the illustrated embodiment, magnets 30 may be spaced apart from each other around the torsion bar 24 and surrounded by the spool 22. Common reference numerals are used to identify common features in the embodiments.

[0057] Referring Figure 3 , the spool 22 may be rotatably connected to the housing 20. The spool 22 may rotate freely relative to the housing 20. For example, the spool 22 may rotate about axis A relative to the housing 20. The spool 22 may be cylindrical in shape. The spool 22 may be adapted to receive the webbing 18, for example, by including a webbing 18 attachment groove (not shown) and allowing the webbing 18 to wind around the spool 22.

[0058] Continuing to refer Figure 3 , the spool 22 may include a first end 58 and a second end 60 that are spaced apart from each other along axis A. The spool 22 may extend annularly about axis A. In other words, the first end 58 and the second end 60 of the spool 22 may extend annularly about axis A. The spool 22 may have a constant cross-section along axis A. For example, the spool 22 may have a circular cross-section.

[0059] The spool 22 may include a first wall 62 located at the first end 58 of the spool 22 and a second wall 64 located at the second end 60 of the spool 22. The first wall 62 and the second wall 64 may respectively surround the first end and the second end 60 of the spool 22. The first wall 62 and the second wall 64 may have any suitable shape. For example, the first wall 62 and the second wall 64 may have an annular shape. In other words, the first wall 62 and the second wall 64 may respectively extend annularly about axis A to the first end and the second end 60 of the spool 22.

[0060] Referring Figure 4 and 7 , the spool 22 may include a cavity 66 that extends from the first end of the spool 22 to the second end 60. The cavity 66 may extend circumferentially along the spool 22 (i.e., along axis A). The cavity 66 may have a constant cross-section along axis A. For example, the cavity 66 may have a circular cross-section. In Figure 6 the illustrated embodiment, the spool 22 may include a groove 68 that extends circumferentially about axis A. The groove 68 may extend through the spool 22 to the cavity 66. The groove 68 may extend any suitable amount along axis A. The groove 68 may be provided between the first end and the second end 60 of the spool 22.

[0061] The webbing 18 may be attached to the spool 22. Specifically, one end of the webbing 18 may be attached to the anchor 42, as described above, and the other end of the webbing 18 may be attached to the spool 22, at which end the webbing 18 begins to wind around the spool 22. The webbing 18 may be formed of a fabric in the shape of a strip.

[0062] Referring Figure 3, the scroll spring 70 can be connected to the scroll 22 and the housing 20. The scroll spring 70 can be tensioned or compressed when the webbing 18 is fully retracted, and the scroll spring 70 can be further loaded in tension or compression either when the webbing 18 extends from the scroll 22. Thus, the scroll spring 70 can apply a force tending to retract the webbing 18. The scroll spring 70 can be a helical torsion spring or any other suitable type of spring.

[0063] The first end 26 and the second end 28 of the torsion bar 24 can be spaced apart from each other along the axis A, as Figure 3 shown. In other words, the torsion bar 24 and the scroll 22 can extend from the respective first ends to the respective second ends. The first end 26 of the torsion bar 24 can be connected to the first end 58 of the scroll 22. For example, the teeth (not numbered) of the first end 26 of the torsion bar 24 can mesh with the teeth (not numbered) of the first end 58 of the scroll 22, as Figure 3 shown, in which case the first end 26 of the torsion bar 24 can be fixed relative to the first end 58 of the scroll 22. The second end 28 of the torsion bar 24 can extend outwardly from the second end 60 of the scroll 22. In other words, the second end 28 of the torsion bar 24 can extend through the second wall 64 of the scroll 22.

[0064] The torsion bar 24 can extend along the axis A by any suitable amount. For example, in the Figure 4 embodiment shown, the torsion bar 24 can extend from the first end (i.e., the first wall 62) of the scroll 22. In the Figures 5 to 7 embodiment shown, the first end 26 of the torsion bar 24 can extend outwardly from the first end (i.e., the first wall 62) of the scroll 22. In other words, the first end 26 of the torsion bar 24 and the second end 28 of the torsion bar 24 can each extend outwardly from the first end and the second end 60 of the scroll 22, respectively. In this case, the torsion bar 24 can extend further along the axis A than the scroll 22.

[0065] When the torsion bar 24 is rotated by the scroll 22 but fixed by the ratchet 54, the torsion bar 24 can be designed to yield rotationally, i.e., plastically deform. In particular, the torsion bar 24 can be formed of a suitable shape, size, and material to yield when subjected to a threshold rotational force. For example, if the ratchet 54 is engaged but the webbing 18 applies a force F on the scroll 22, the torsion bar 24 can prevent the scroll 22 from rotating unless the force F exceeds the threshold, in which case the rotational yield can allow the scroll 22 to rotate.

[0066] When the torsion bar 24 yields, one of the magnet 30 and the rotor 32 fixed to the torsion bar 24 rotates relative to the other of the magnet 30 and the rotor 32 fixed to the spool 22. For example, when the ratchet 54 engages with the second end 28 of the torsion bar 24, the first end 26 of the torsion bar 24 (i.e., the spool 22) can rotate relative to the second end 28 of the torsion bar 24. The first end 26 of the torsion bar 24 can rotate more than the second end 28 of the torsion bar 24, that is, the rotation of the torsion bar 24 can increase along the torsion bar 24 from the second end 28 to the first end 26. In this case, one of the magnet 30 and the rotor 32 can have a speed relative to the other of the magnet 30 and the rotor 32. When the torsion bar 24 is twisted, the speed can gradually increase.

[0067] During a vehicle collision, when one of the magnet 30 and the rotor 32 rotates relative to the other of the magnet 30 and the rotor 32, the seat belt retractor 16 can apply a resistance force Fd to increase the load on the webbing 18 and absorb energy from the occupant. As described above, the resistance force Fd can counteract the force F of the webbing 18 and can be proportional to the speed of one of the magnet 30 and the rotor 32, that is, when the speed increases, the resistance force Fd can increase. The torsion bar 24 can gradually increase the load through the webbing 18; that is, when the resistance force Fd increases (i.e., when the torsion bar 24 rotates), the force that rotationally yields the torsion bar 24 can increase, so that when the torsion bar 24 is further twisted, the load on the webbing 18 gradually increases.

[0068] The resistance force Fd can be formed by eddy currents. The relative movement of the rotor 32 with respect to the magnet 30 can induce a current in the rotor 32. Specifically, the magnet 30 can include a magnetic field, and the relative movement of the rotor 32 with respect to the magnetic field can induce a current in the rotor 32. The current can flow in a direction opposite to the speed of one of the rotor 32 and the magnet 30. In other words, the current can flow in a direction opposite to the force F. The current can generate a counter magnetic field, and the counter magnetic field applies a resistance force Fd opposite to the relative movement of the rotor 32 and the magnet 30.

[0069] Reference Figure 6 and 7 and, the seat belt retractor 16 can include a plate 72 supported by the torsion bar 24. The plate 72 can be fixed to the torsion bar 24, for example. In other words, when the torsion bar 24 yields, the plate 72 can rotate relative to the spool 22. The plate 72 can be disposed at any suitable position along the axis A. For example, in Figure 6 the illustrated embodiment, the plate 72 can be disposed in the slot 68 of the spool 22. In Figure 7 the illustrated embodiment, the plate 72 can be disposed at the second end 60 of the spool 22. In this case, the plate 72 can be the second wall 64 of the spool 22, that is, surrounding the first end 58 of the spool 22.

[0070] Continuing to refer toFigure 6 and 7 , the plate 72 may extend from a first side 74 to a second side 76 along the torsion bar 24 (i.e., axis A). The plate 72 may extend circumferentially from the torsion bar 24 to a surface 78 spaced apart from the torsion bar 24. The surface 78 may extend from the first side 74 of the plate 72 to the second side 76 along the axis A. The surface 78 may include a plurality of notches 80 spaced apart from each other about the axis A. In other words, the plurality of notches 80 may be spaced apart circumferentially about the axis A. The notches 80 may be disposed at any suitable location on the surface 78, i.e., between the first side 74 and the second side 76 of the plate 72. The notches 80 may extend from the surface 78 toward the axis A. In other words, the notches 80 may be cutouts on the surface 78 of the plate 72. The notches 80 may have any suitable shape, e.g., rectangular, square, etc.

[0071] The plate 72 may have any suitable shape. Figure 6 In the illustrated embodiment, the plate 72 may have a circular shape. Figure 7 In the illustrated embodiment, the plate 72 may have a frustum shape.

[0072] The magnet 30 may be supported by any suitable component of the seat belt retractor 16. Figure 4 and 5 In the illustrated embodiment, the seat belt retractor 16 may include a support member 82 fixed relative to the spool 22. Figure 4 In the illustrated embodiment, the support member 82 may be disposed within the cavity 66 of the spool 22 and secured to the spool 22. Figure 5 In the illustrated embodiment, the support member 82 may be fixed to the reel 22 directly or via an intermediate member, such as a rod (not shown) extending from the reel 22 to the support member 82. The support member 82 may extend from one magnet to another magnet, such as along an axis A. Figure 5 As shown. Figure 6 and 7 In the illustrated embodiment, the support member 82 may be a plate 72 and may be fixed to the torsion bar 24. In this case, the magnets 30 may be disposed in a plurality of recesses 80 on the plate 72. Specifically, one magnet may be disposed in each recess. Figure 7 In the illustrated embodiment, one surface 76 of the plate 72 may be the first wall 62 of the spool 22 .

[0073] The magnet 30 may be disposed at any suitable position along the axis A. For example, Figure 4 , 6 In the embodiment shown in FIG. 7 , the magnet 30 may be disposed between the first end and the second end 60 of the reel 22. Figure 4 and 7In the illustrated embodiment, the magnet 30 may be disposed in the cavity 66 of the spool 22. In Figure 6 In the illustrated embodiment, the magnet 30 may be disposed in the slot 68 of the spool 22. In Figure 5 In the illustrated embodiment, the magnet 30 may be disposed outside the cavity 66 of the spool 22. In other words, the first end 58 of the spool 22 may be disposed between the second end 60 of the spool 22 and the magnet 30.

[0074] The magnets 30 may be spaced apart from each other in any suitable manner. For example, in Figure 4 and 5 In the illustrated embodiment, the magnets 30 may be spaced apart from each other along the torsion bar 24 (i.e., axis A). In Figure 6 and 7 In the illustrated embodiment, the magnets 30 may be circumferentially spaced apart from each other about the torsion bar 24 (i.e., axis A).

[0075] The magnets 30 may have any suitable shape. For example, in Figure 4 and 5 In the illustrated embodiment, the magnets 30 may extend circumferentially from the torsion bar 24. In this case, the magnets 30 may have an annular shape such that the torsion bar 24 extends through a hole (not numbered) of the magnets 30. In Figure 6 and 7 In the illustrated embodiment, the magnets 30 may have the same shape as the notch, such as rectangular, square, etc.

[0076] As described above, the rotor 32 is disposed adjacent to the magnet 30. For example, in Figure 4 and 5 In the illustrated embodiment, the rotor 32 may be disposed between the magnets 30 along the torsion bar 24 (i.e., axis A). Specifically, in Figure 4 In the illustrated embodiment, one magnet may be disposed between the rotor 32 and the first end 58 of the spool 22 (i.e., the first end 26 of the torsion bar 24), and the other magnet may be disposed between the rotor 32 and the second end 60 of the spool 22 (i.e., the second end 60 of the spool 22). In Figure 5 In the illustrated embodiment, the first end 58 of the spool 22 may be disposed between the second end 60 of the spool 22 and the rotor 32. In this case, one magnet may be disposed between the rotor 32 and the first end 58 of the spool 22. In Figure 6 and 7 In the illustrated embodiment, the rotor 32 may extend about the magnet 30 with respect to the torsion bar 24 (i.e., axis A). In other words, the magnet 30 may be disposed between the rotor 32 and the torsion bar 24.

[0077] The rotor 32 may be supported by any suitable component of the seat belt retractor 16. For example, in Figure 4 ,5 In the embodiments shown in FIGS. 6 and 7, the rotor 32 can be supported by the torsion bar 24. The rotor 32 can be fixed to the torsion bar 24. In this case, the rotor 32 can extend circumferentially from the torsion bar 24. In Figure 6 the embodiment shown, the rotor 32 can be supported by the spool 22. In other words, the rotor 32 can be fixed to the spool 22, i.e., fixed relative to the torsion bar 24. In this case, the rotor 32 can be spaced apart from the torsion bar 24 and extend circumferentially about the axis A.

[0078] The rotor 32 can have any suitable shape. For example, in Figures 4 to 6 the embodiment shown, the rotor 32 can have an annular shape. In Figure 7 the embodiment shown, the rotor 32 can have a frustum shape.

[0079] The rotor 32 can be formed of any suitable conductive material. In other words, the rotor 32 can be formed of any material suitable for carrying an electric current. For example, the rotor 32 can be formed of any suitable metal, such as steel, copper, aluminum, etc.

[0080] During a vehicle collision, the activation sensor can trigger the locking device, e.g., cause the pawl 56 to engage the ratchet 54. The pawl 56 can move from the unlocked position to the locked position and engage the ratchet 54. Substantially simultaneously, the occupant of the seat 12 has a forward momentum relative to the seat 12 and applies a tension to the webbing 18. The tension in the webbing 18 tends to pull the webbing 18 out of the spool 22. The ratchet 54 connected to the spool 22 by the torsion bar 24 can prevent the rotation of the spool 22 until the tension in the webbing 18 exceeds a threshold force, thereby deforming the torsion bar 24.

[0081] When the torsion bar 24 is deformed, one of the magnet 30 and the rotor 32 moves relative to the other, because one of the magnet 30 and the rotor 32 is fixed relative to the spool 22, and the other of the magnet 30 and the rotor 32 rotates relative to the spool 22. For example, in Figures 4 to 6 the embodiment shown, the magnet 30 is fixed relative to the spool 22, and the rotor 32 rotates relative to the spool 22. In Figure 6 the embodiment shown. The rotor 32 is fixed relative to the spool 22, and the magnet 30 rotates relative to the spool 22. When the rotor 32 and the magnet 30 rotate relative to each other, the force F applied by the webbing 18 is counteracted by the drag force Fd, such that the seat belt retractor 16 limits the load applied to the occupant by the webbing 18. The limited load can help reduce the chest compression of the occupant and absorb the energy of the occupant during a vehicle collision.

[0082] The present disclosure has been described in an illustrative manner, and it is to be understood that the terminology used is intended to be of a descriptive nature rather than restrictive. Many modifications and variations of the present disclosure are possible in light of the above teachings, and the present disclosure may be practiced in a manner different from that specifically described.

Claims

1. A seat belt retractor, comprising: A housing; A spool rotatably supported by the housing; A torsion bar having a first end and a second end, the first end being fixed to the spool and the second end being fixable relative to the housing; A plurality of magnets circumferentially spaced apart from each other about the torsion bar; A rotor disposed near the magnets, one of the magnets and the rotor being fixed relative to the spool and the other of the magnets and the rotor being rotatable relative to the spool, the rotor including a conductive material; Wherein the rotor extends about the magnets around the torsion bar; And A plate including a plurality of notches circumferentially spaced apart from each other about the torsion bar, one magnet being disposed in each notch.

2. The seat belt retractor according to claim 1, wherein the rotor is fixed to the spool.

3. The seat belt retractor according to claim 1, further comprising a webbing having an end, the end of the webbing being attached to the spool.

4. The seat belt retractor according to claim 1, wherein the spool includes a first end and a second end spaced apart from each other along an axis.

5. The seat belt retractor according to claim 4, wherein the torsion bar and the spool extend coaxially from respective first ends to respective second ends.

6. The seat belt retractor according to claim 4, wherein the magnets are disposed between the first end and the second end of the spool.

7. The seat belt retractor according to claim 4, wherein the first end of the torsion bar is fixed to the first end of the spool.

8. The seat belt retractor according to claim 1, wherein the spool defines a cavity extending circumferentially about an axis, and the magnets are disposed in the cavity.

9. The seat belt retractor according to claim 1, wherein the spool includes a groove extending circumferentially about an axis, and some of the magnets are disposed in the groove.

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