Seatbelt retractor and seatbelt device

Abstract

This seatbelt retractor is provided with a winding speed suppression unit for suppressing the rotation speed of a spool in the winding direction. The winding speed suppression unit includes: a support plate; a cam plate that is disposed on the main surface of the support plate, can rotate in conjunction with the rotation shaft of the spool, and is provided with a projection extending radially outward from the rotation center; a shoe that is connected to the support plate, is disposed radially outward of the cam plate, and is provided with a contact surface that can come into contact with the projection of the cam plate; and an inner peripheral surface of a cover serving as a regulation surface that is disposed radially outward of the shoe.

Description

Seat belt retractor and seat belt device

[0001] The present disclosure relates to a seat belt retractor and a seat belt device.

[0002] Due to a sudden retracting action of the seat belt retractor on the webbing, there is a possibility that the tongue of the seat belt device through which the webbing is inserted may come into contact with an occupant, the vehicle interior, etc. In order to reduce the effects of such contact and to improve the usability of the seat belt device, a method for suppressing an increase in the retracting speed of the webbing by the seat belt retractor has been proposed (for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2015-227077

[0004] However, in the conventional method, an element for suppressing an increase in the winding speed of the webbing is added to the seat belt retractor, which increases the weight and size of the entire device, leaving room for improvement.

[0005] An object of the present disclosure is to provide a seat belt retractor and a seat belt device that can suppress an increase in the weight and size of the entire device and can also suppress an increase in the winding speed of the webbing.

[0006] A seat belt retractor according to one aspect of an embodiment of the present invention includes a spool around which a webbing is wound, a biasing portion that biases the spool in a winding direction in which the spool winds the webbing, and a winding speed suppressing portion that suppresses the rotation speed of the spool in the winding direction caused by the biasing portion, and the winding speed suppressing portion includes a plate-shaped support member having a main surface on the side where a tip end of the shaft member is inserted, the main surface being disposed on the main surface side of the support member and coupled to the tip end of the shaft member that protrudes from the hole toward the main surface side so as to be rotatable in conjunction with the tip end of the shaft member, and extending in a centrifugal direction from a rotation center. The spool has a rotating member on which a protrusion is provided, a resistance member connected to the support member, positioned centrifugal from the rotating member, and provided with a contact surface that can come into contact with the protrusion of the rotating member, and a regulating surface positioned centrifugal from the support member and extending along the rotational direction of the support member, wherein the contact surface of the resistance member is formed so that when the spool rotates in the winding direction, it is pressed by the protrusion in accordance with a change in the relative positional relationship between the protrusion of the rotating member and the resistance member along the rotational direction, causing the resistance member to move centrifugal to a position where it comes into contact with the regulating surface, and the winding speed suppressing unit suppresses the rotational speed of the spool in the winding direction by contact between the resistance member and the regulating surface.

[0007] According to the present disclosure, it is possible to provide a seat belt retractor and a seat belt device that can suppress an increase in the weight and size of the entire device and can also suppress an increase in the winding speed of the webbing.

[0008] FIG. 3 is a diagram showing a schematic configuration of a seat belt device according to an embodiment; FIG. 4 is a perspective view of a seat belt retractor according to a first embodiment; FIG. 5 is a perspective view showing the assembled state of each element of the main part of the winding speed suppression part in FIG. 2; FIG. 6 is a diagram showing the positional relationship of the inner peripheral surfaces of the cam plate, shoe, and cover of the winding speed suppression part according to the first embodiment when the spool is rotating in the unwinding direction; FIG. 7 is a diagram showing the positional relationship of the inner peripheral surfaces of the cam plate, shoe, and cover of the winding speed suppression part according to the first embodiment when the spool is rotating in the winding direction; FIG. 1 is a diagram showing the positional relationship between the shoe and the inner peripheral surface of the cover; FIG. 2 is a diagram showing the positional relationship between the cam plate, shoe, and inner peripheral surface of the cover of a winding speed suppression unit according to a modified example of the first embodiment when the spool is rotating in the winding direction; FIG. 3 is a perspective view showing the assembled state of each element of the main part of the winding speed suppression unit according to the second embodiment; FIG. 4 is a diagram showing the positional relationship between the cam plate, shoe, and inner peripheral surface of the cover of a winding speed suppression unit according to the second embodiment when the spool is rotating in the unwinding direction;

[0009] Hereinafter, embodiments will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions will be omitted.

[0010] In the following description, the X direction, Y direction, and Z direction shown in each drawing relating to the seat belt retractor 3 from Fig. 2 onwards are perpendicular to one another. The X direction is the extension direction of the axial center CA of the spool 12 and the rotating shaft 13. The Y direction and Z direction are each centrifugal directions from the rotating shaft 13 of the spool 12, with the Y direction typically being the horizontal direction and the Z direction being the up-down direction. In addition, in the extension direction of the axial center CA of the seat belt retractor 3, the side on which the retraction speed suppression unit 20 is located is referred to as the X positive direction side, and the opposite side is referred to as the X negative direction side.

[0011] In addition, in the drawings from Figure 3 onwards that show the positional relationship between the support plate 26, the cam plate 27, and the pair of shoes 28A, 28B, the center (axis center CA) of the circular shape of the support plate 26 is referred to as the "rotation center," and the direction moving away from the rotation center toward the outside in the radial direction is referred to as the "centrifugal direction," "centrifugal side," or "radially outer side." The direction toward the rotation center in the radial direction is also referred to as the "center side" or "radially inner side." The direction of movement around the rotation center at an equal distance from the rotation center is also referred to as the "circumferential direction."

[0012] First Embodiment First, an example of the configuration of a seat belt device 1 to which a seat belt retractor 3 according to a first embodiment is applied will be described with reference to Fig. 1. Fig. 1 is a diagram showing a schematic configuration of the seat belt device 1 according to the embodiment.

[0013] The seat belt device 1 is an example of an in-vehicle system installed in a vehicle. As shown in Fig. 1, the seat belt device 1 includes, for example, a seat belt 4, a seat belt retractor 3, a shoulder anchor 6, a tongue 7, and a buckle 8.

[0014] The seat belt 4 is an example of a webbing that restrains an occupant 9 seated in a vehicle seat 2, and is a belt-shaped member that is retracted and retracted around a seat belt retractor 3. In the following description, the seat belt 4 may also be referred to as "webbing 4." A belt anchor 5 at the tip of the seat belt 4 is fixed to the seat 2 or to a vehicle body in the vicinity of the seat 2.

[0015] The seat belt retractor 3 is an example of a retracting device that enables retracting or unretracting of the seat belt 4, and when deceleration equal to or greater than a predetermined value is applied to the vehicle, such as during a vehicle collision, the seat belt retractor 3 restricts the seat belt 4 from being unretracted from the seat belt retractor 3. The seat belt retractor 3 is fixed to the seat 2 or to a vehicle body in the vicinity of the seat 2.

[0016] The shoulder anchor 6 is an example of a belt insertion tool through which the seat belt 4 is inserted, and is a member that guides the seat belt 4 pulled out from the seat belt retractor 3 toward the shoulder of the occupant 9 .

[0017] The tongue 7 is an example of a belt insertion tool through which the seat belt 4 is inserted, and is a component slidably attached to the seat belt 4 guided by the shoulder anchor 6 .

[0018] The buckle 8 is a component to which the tongue 7 is releasably fastened, and is fixed to the seat 2 or a part of the vehicle body in the vicinity of the seat 2, for example.

[0019] Next, the configuration of the seat belt retractor 3 according to the first embodiment will be described with reference to Figures 2 and 3. Figure 2 is a perspective view of the seat belt retractor 3 according to the first embodiment. In Figure 2, elements of the seat belt retractor 3 relating to a winding speed suppression unit 20, which will be described later, are shown in an exploded state. Figure 3 is a perspective view showing the assembled state of each element of the main part of the winding speed suppression unit 20 in Figure 2.

[0020] As shown in FIG. 2 , the seat belt retractor 3 includes a retractor body 10 and a retraction speed suppressor 20 .

[0021] The retractor body 10 has a frame 11 that is formed so as to be connectable and fixed to the vehicle body. One end of the webbing 4 is secured to the frame 11, and a spool 12 around which the webbing 4 is wound is rotatably housed within the frame 11. The spool 12 is disposed so as to be rotatable about an axis CA along the X direction, and a rotation shaft 13 is provided at the rotation center of the spool.

[0022] A pretensioner is also mounted on the frame 11. When the pretensioner is activated, the spool 12 receives a rotational force from the pretensioner, which causes the spool 12 to rotate in a direction (winding direction) α in which the webbing 4 is retracted. In the example of Fig. 2, the winding direction α is a counterclockwise direction when viewed from the X positive direction side. On the other hand, the direction (unwinding direction) β in which the webbing 4 is unwound from the spool 12 is a clockwise direction opposite to the winding direction α when viewed from the X positive direction side.

[0023] A power spring 14 is connected to the rotating shaft 13. The power spring 14 is an example of a biasing portion that biases the spool 12 in a winding direction α in which the spool 12 winds the webbing 4. As illustrated in FIG. 2 , the power spring 14 is housed in a housing 15 provided on a surface of the frame 11 on the X-positive side. The housing 15 is a recess that is substantially circular in shape when viewed from the X-positive side, and the rotating shaft 13 is disposed at the center of the circle (i.e., the position of the axis CA) so as to protrude in the X-positive direction. The power spring 14 is disposed in a spiral shape around the rotating shaft 13 inside the housing 15, with one end 14A on the central side connected to the rotating shaft 13 and the other end 14B on the distal side connected to a portion 15A of the circular inner circumferential surface of the outer edge of the housing 15.

[0024] The winding speed suppressing unit 20 suppresses the rotation speed of the spool 12 in the winding direction α caused by the bias of the spiral spring 14. As shown in Figure 2, for example, the winding speed suppressing unit 20 is disposed adjacent to the spiral spring 14 and the housing portion 15 on the X-positive side, and is connected to the rotating shaft 13 and is also connected and fixed to the frame 11 of the retractor body 10.

[0025] Winding speed suppression unit 20 has housing 21 and cover 22. Housing 21 is formed so that main surface 21A on the X negative side can abut against surface 11A of frame 11 of retractor body 10, on which spiral spring 14 and accommodating portion 15 are provided. Housing 21 is provided with accommodating portion 21C that opens to main surface 21B on the X positive side and is recessed toward main surface 21A.

[0026] The cover 22 is formed so that its main surface 22A on the X-negative side can abut against the main surface 21B of the housing 21. The abutment of the main surface 22A of the cover 22 with the main surface 21B of the housing 21 closes the accommodation portion 21C of the housing 21. The cover 22 also has an accommodation portion 22B recessed from the main surface 22A toward the X-positive side. The accommodation portion 22B has a substantially circular recessed shape when viewed from the X-negative side. That is, when viewed from the X-positive side, the accommodation portion 22B forms a substantially cylindrical peripheral wall 22C of the cover 22. A support portion 22D is provided at the center of the circle of the accommodation portion 22B (i.e., at the position of the axis CA) to which the tip of the rotary shaft 13 can rotatably engage.

[0027] When the cover 22 is attached to the housing 21, the accommodating portion 21C of the housing 21 and the accommodating portion 22B of the cover 22 can form an integrated internal space.

[0028] The winding speed suppression unit 20 has, as elements to be housed in the internal space, a bush gear 23, an idle gear 24, a spindle gear 25, a support plate 26 (support member), a cam plate 27 (rotating member), a pair of shoes 28A, 28B (resistance members), and a pair of coil springs 29A, 29B (biasing members).

[0029] A through-hole 21D is provided in the bottom surface of the accommodation portion 21C of the housing 21. The bush gear 23 is arranged so that its main surface and rotation center face in the X direction. A rotation shaft 23A provided on the main surface of the bush gear 23 on the negative X direction side is inserted into the through-hole 21D of the housing 21, protrudes further in the negative X direction than the main surface 21A of the housing, and is connected to be coaxial with the rotation shaft 13 of the retractor main body 10. The bush gear 23 is connected to be rotatable integrally with the rotation shaft 13 of the retractor main body 10, for example, by fitting the rotation shaft 23A into the rotation shaft 23A. In other words, the bush gear 23 is arranged so that its rotation center is located at the axis center CA.

[0030] The idle gear 24 and the spindle gear 25 are also arranged so that their principal surfaces and rotation axes face the X direction, similar to the bush gear 23. The idle gear 24 and the spindle gear 25 are arranged at the same position in the X direction while meshing with each other. The idle gear 24 and the spindle gear 25 are arranged on the positive X direction side with respect to the bush gear 23.

[0031] A rotation shaft 21E protruding in the X-positive direction is provided on the bottom surface of the accommodation portion 21C of the housing 21, at a position on the Z-negative side of the through-hole 21D. A through-hole 24A is provided at the rotation center of the idle gear 24, and the rotation shaft 21E is inserted through the through-hole 24A, thereby allowing the idle gear 24 to rotate around the rotation shaft 21E. A small-diameter gear (not shown) is provided on the main surface on the X-negative side of the idle gear 24, concentrically arranged with the gears provided on the outer peripheral side surface. This small-diameter gear meshes with the bush gear 23. Meanwhile, the gears provided on the outer peripheral side surface of the idle gear 24 mesh with the spindle gear 25. A rotation shaft 25A protruding in the X-positive direction is provided on the main surface on the X-positive side of the spindle gear 25. The rotation shaft 25A of the spindle gear 25 is arranged coaxially with the rotation shaft 23A of the bush gear 23. That is, like the bush gear 23, the spindle gear 25 is also arranged so that the center of rotation is located at the axis CA.

[0032] The bush gear 23, idle gear 24, and spindle gear 25 mesh with each other in this order to transmit power. The small-diameter gear (not shown) of the idle gear 24 is formed so that its gear ratio is larger than that of the bush gear 23. The spindle gear 25 is formed so that its gear ratio is larger than that of the idle gear 24. In other words, when the rotation shaft 23A of the bush gear 23 connected to the rotation shaft 13 of the retractor body 10 is used as a reference, the bush gear 23, idle gear 24, and spindle gear 25 can be said to constitute an accelerating gear 30 that can relatively increase the rotational speed of the rotation shaft 25A of the spindle gear 25.

[0033] The support plate 26 is a disk-shaped member and is arranged with its main surface facing the X direction. The diameter of the disk shape of the support plate 26 is formed to be smaller than the inner diameter of the circular housing portion 22B of the cover 22, for example, so that the support plate 26 can be housed in the housing portion 22B of the cover 22.

[0034] The support plate 26 is disposed on the X positive side of the speed-up gear 30. The support plate 26 is disposed such that the center of its disk shape is located at the axis CA. A through hole 26A is provided at the center of the disk shape of the support plate 26. The rotation shaft 25A of the spindle gear 25 is inserted into the through hole 26A from the X negative side and is disposed so as to protrude further toward the X positive side than a main surface 26B of the spindle gear 25 on the X positive side. The through hole 26A has a hole diameter larger than the maximum diameter of the rotation shaft 25A, but is large enough not to impede the rotation of the rotation shaft 25A of the spindle gear 25 when the spindle gear 25 rotates relative to the support plate 26.

[0035] Cam plate 27 is an example of a rotating member that is disposed on main surface 26B of support plate 26 on the X positive direction side and is coupled to the tip end of rotation shaft 25A of spindle gear 25, which protrudes from through hole 26A toward main surface 26B, so as to be rotatable in conjunction with the tip end. A through hole 27C is provided at the rotation center of cam plate 27. The shape of through hole 27C is the same as the shape of rotation shaft 25A of spindle gear 25, and is formed so that rotation shaft 25A can be inserted therethrough. The shapes of through hole 27C and rotation shaft 25A are formed to have long and short sides that extend radially and are orthogonal to each other, as shown in FIG. 2, for example. With this shape, when spindle gear 25 rotates with rotation shaft 25A of spindle gear 25 inserted through through hole 27C of cam plate 27 (see Figures 4, 5, etc.), a rotational drive force is transmitted to cam plate 27 via rotation shaft 25A and through hole 27C, allowing cam plate 27 to rotate integrally with spindle gear 25. Note that the shapes of rotation shaft 25A and through hole 27C may be shapes other than those exemplified in Figure 2, as long as the rotation shaft 25A can transmit the rotational drive force without rotating freely relative to through hole 27C.

[0036] 3, the cam plate 27 has a pair of protrusions 27A, 27B extending in the centrifugal direction from the center of rotation. The pair of protrusions 27A, 27B are formed to extend on opposite radial sides of the center of rotation. The radial dimensions of the pair of protrusions 27A, 27B are formed to be smaller than the radius of the support plate 26. It is preferable that the pair of protrusions 27A, 27B be formed so that their shapes when viewed in the X direction are point-symmetric with respect to the axis CA, as exemplified in, for example, FIGS. 2 and 3.

[0037] The pair of shoes 28A, 28B is an example of a resistance member connected to the support plate 26 on the main surface 26B of the support plate 26. As shown in Fig. 3, the pair of shoes 28A, 28B is disposed on the centrifugal side of the cam plate 27 on the main surface 26B of the support plate 26, and contact surfaces 28A1, 28B1 that can come into contact with the protrusions 27A, 27B of the cam plate 27 are provided on the central side.

[0038] A pair of pivot shafts 26C, 26D are provided on the main surface 26B of the support plate 26, standing parallel to the rotation axis 13. That is, the pivot shafts 26C, 26D are parallel to the axis CA and positioned equidistant from the axis CA in the radial direction. The axes CB, CC of the pivot shafts 26C, 26D extend along the X direction. The pair of shoes 28A, 28B have through holes 28A2, 28B2 through which the pivot shafts 26C, 26D can be inserted. The shoes 28A, 28B are connected to the support plate 26 so as to be rotatable about the pivot shafts 26C, 26D by inserting the pivot shafts 26C, 26D into the through holes 28A2, 28B2.

[0039] The pair of shoes 28A, 28B are crescent-shaped members extending along the circumferential direction of the support plate 26. The through holes 28A2, 28B2 provided in each shoe 28A, 28B are located on one end (base end) side along the circumferential direction, allowing the other end (tip end) side of each shoe 28A, 28B to rotate in the radial direction of the support plate 26 around the rotation shafts 26C, 26D.

[0040] In particular, in this embodiment, the contact surfaces 28A1, 28B1 of each shoe 28A, 28B face the center of the support plate 26. The radially outward-facing outer peripheral surfaces 28A5, 28B5 of each shoe 28A, 28B are positioned opposite the inner peripheral surface 22E of the peripheral wall 22C of the cover 22 when the shoes 28A, 28B are connected to the support plate 26 and housed in the housing portion 22B of the cover 22. The inner peripheral surface 22E of the peripheral wall 22C of the cover 22 is an example of a restricting surface that extends along the rotational direction of the support plate 26, toward the centrifugal side of the support plate 26. The outer peripheral surfaces 28A5, 28B5 are preferably curved surfaces with the same curvature as the inner peripheral surface 22E of the substantially cylindrical peripheral wall 22C. This allows each shoe 28A, 28B to be in surface contact with the inner peripheral surface 22E, thereby efficiently generating contact resistance.

[0041] The contact surfaces 28A1, 28B1 of the shoes 28A, 28B are formed so that, when the spool 12 rotates in the winding direction α, the contact surfaces 28A1, 28B1 are pressed by the protrusions 27A, 27B of the cam plate 27 in response to a change in the relative positional relationship between the protrusions 27A, 27B of the cam plate 27 and the shoes 28A, 28B along the rotational direction, causing the shoes 28A, 28B to move radially to a position where they contact the inner circumferential surface 22E of the cover 22 (see FIG. 5 ). As shown in FIG. 3 and other figures, the contact surfaces 28A1, 28B1 are curved such that the radial distance between the contact surfaces 28A1, 28B1 and the outer circumferential surfaces 28A5, 28B5 of the shoes 28A, 28B decreases from the base end toward the tip end. In other words, the contact surfaces 28A1, 28B1 are curved such that the radial position of the contact surfaces 28A1, 28B1 shifts radially toward the centrifugal side as they move from the base end toward the tip end. Due to the shape of contact surfaces 28A1, 28B1, the more the contact positions with protrusions 27A, 27B of cam plate 27 move toward the base end, the more protrusions 27A, 27B press contact surfaces 28A1, 28B1 centrifugally, causing shoes 28A, 28B to rotate centrifugally around rotation shafts 26C, 26D. As a result of this rotation, shoes 28A, 28B move centrifugally to positions where outer peripheral surfaces 28A5, 28B5 contact inner peripheral surface 22E of peripheral wall 22C of cover 22.

[0042] The winding speed suppression unit 20 can suppress the rotational speed of the spool 12 in the winding direction α by bringing the shoes 28A, 28B into contact with the inner surface 22E of the peripheral wall 22C of the cover 22, which serves as a regulating surface.

[0043] The winding speed suppression unit 20 also includes a pair of coil springs 29A, 29B as an example of a biasing member connected between each shoe 28A, 28B and the main surface 26B of the support plate 26 to bias each shoe 28A, 28B toward the center. As shown in FIG. 3 , each shoe 28A, 28B is provided with a spring connecting portion 28A3, 28B3 that protrudes further toward the center from the radially inner contact surface 28A1, 28B1. The spring connecting portion 28A3, 28B3 is formed to extend radially around the axis center CB, CC of the through holes 28A2, 28B2. Meanwhile, as shown in FIG. 3 , spring connecting portions 26E, 26F are also provided on the main surface 26B of the support plate 26. A pair of coil springs 29A, 29B have one end connected to spring connection portions 28A3, 28B3 of shoes 28A, 28B, and the other end connected to spring connection portions 26E, 26F of support plate 26, thereby connecting each shoe 28A, 28B to support plate 26.

[0044] Furthermore, the pair of coil springs 29A, 29B are preferably connected to the spring connecting portions 28A3, 28B3 of the shoes 28A, 28B and the spring connecting portions 26E, 26F of the support plate 26 in a state where they are contracted from their natural lengths. In this configuration, the pair of coil springs 29A, 29B are biased in a direction that separates the spring connecting portions 28A3, 28B3, to which both ends are connected, from the spring connecting portions 26E, 26F. This allows the shoes 28A, 28B to constantly receive a biasing force from the coil springs 29A, 29B via the spring connecting portions 28A3, 28B3 in a direction that rotates them toward the center of the support plate 26 about the axes CB, CC, so that the shoes 28A, 28B can be prevented from moving toward the centrifugal side due to external forces such as centrifugal force.

[0045] 3, the spring connecting portions 26E, 26F of the support plate 26 are disposed at positions equidistant radially outward from the axis CA of the support plate 26 and on opposite sides of the axis CA. As a result, the spring connecting portions 26E, 26F of the support plate 26 can also function as restricting portions that restrict each of the pair of shoes 28A, 28B from rotating toward the center of the support plate 26 from a predetermined position on the radial side.

[0046] Furthermore, as shown in Fig. 3, the spring connecting portions 26E, 26F preferably have opposing surfaces that face radially outward and are positioned opposite the contact surfaces 28A1, 28B1 of the shoes 28A, 28B. Furthermore, the opposing surfaces are preferably formed with the same curvature as the portions of the contact surfaces 28A1, 28B1 that contact the opposing surfaces. This configuration allows the spring connecting portions 26E, 26F to come into surface contact with the contact surfaces 28A1, 28B1 of the shoes 28A, 28B when the pair of shoes 28A, 28B rotate toward the center and abut against the spring connecting portions 26E, 26F. This reduces the impact on the spring connecting portions 26E, 26F, thereby extending the life of the device.

[0047] The pair of shoes 28A, 28B are provided with locking portions 28A4, 28B4 that lock onto the projections 27A, 27B of the cam plate 27 and restrict movement of the shoes 28A, 28B toward the centrifugal side at ends of the contact surfaces 28A1, 28B1 that are opposite to the winding direction α and in the unwinding direction β in which the webbing 4 is unwound from the spool 12, i.e., at the tip ends opposite the base ends where the through holes 28A2, 28B2 and the pivot shafts 26C, 26D are provided. As shown in FIG. 3, for example, the locking portions 28A4, 28B4 are provided to extend from the tip ends of the shoes 28A, 28B toward the center of the support plate 26 and toward the base ends of the shoes 28A, 28B, thereby forming acute-angled recesses between the contact surfaces 28A1, 28B1. Meanwhile, protrusions 27D, 27E that protrude in the pull-out direction β are formed at the tips of protrusions 27A, 27B of cam plate 27. These protrusions 27D, 27E enter recesses formed by locking portions 28A4, 28B4 and contact surfaces 28A1, 28B1, thereby locking each shoe 28A, 28B to cam plate 27. This restricts each shoe 28A, 28B from moving centrifugally relative to cam plate 27.

[0048] It is preferable that the pair of shoes 28A, 28B be formed so that when attached to the support plate 26, their shape as viewed in the X direction is point symmetrical with respect to the axis CA as the center of symmetry, as illustrated in Figures 2 and 3, for example.

[0049] Next, the operation of the winding speed suppression unit 20 according to the first embodiment will be described with reference to Figures 4 and 5. Figure 4 is a diagram showing the positional relationship between the cam plate 27, shoes 28A and 28B, and inner circumferential surface 22E of the cover 22 of the winding speed suppression unit 20 according to the first embodiment when the spool 12 is rotating in the unwinding direction β. Figure 4 shows a plan view of the above-mentioned elements as viewed from the X positive side. Figure 4 shows the winding speed suppression unit 20 in an inactive state.

[0050] When the spool 12 is rotating in the unwinding direction β, the bush gear 23, which rotates integrally with the rotary shaft 13 of the spool 12, also rotates in the unwinding direction β. Therefore, the spindle gear 25, to which power is transmitted via the bush gear 23 and the idle gear 24, also rotates in the unwinding direction β. As a result, as shown in Figure 4, the rotary shaft 25A of the spindle gear 25 also rotates in the unwinding direction β.

[0051] Rotation shaft 25A of spindle gear 25 passes through through hole 26A of support plate 26 and is inserted into through hole 27C of cam plate 27, so cam plate 27 also receives the rotational driving force via through hole 27C. As a result, cam plate 27 first rotates in conjunction with rotation shaft 25A relative to support plate 26 in the pull-out direction β.

[0052] Thereafter, the pair of projections 27A, 27B of cam plate 27 abut against the locking portions 28A4, 28B4 of shoes 28A, 28B, respectively, and protruding portions 27D, 27E of projections 27A, 27B enter the recesses formed by the locking portions 28A4, 28B4 and the contact surfaces 28A1, 28B1. At this time, the pair of shoes 28A, 28B are coupled to cam plate 27, and a rotational driving force is transmitted in the pulling-out direction β via cam plate 27. This rotational driving force is also transmitted to support plate 26 via through holes 28A2, 28B2 of the pair of shoes 28A, 28B and pivot shafts 26C, 26D of support plate 26.

[0053] At this time, the pair of shoes 28A, 28B are not pressed toward the centrifugal side by the cam plate 27, and therefore are rotated toward the axis CA of the support plate 26 by the biasing force of the coil springs 29A, 29B, as shown by arrow A in FIG. 4 . As a result, the pair of shoes 28A, 28B are positioned radially at positions where their contact surfaces 28A1, 28B1 abut against the spring connecting portions 26E, 26F of the support plate 26, respectively. In this state, the outer peripheral surfaces 28A5, 28B5 of each shoe 28A, 28B are positioned closer to the center than the outer edge of the disc-shaped support plate 26. Therefore, each shoe 28A, 28B is not in contact with the inner peripheral surface 22E of the cover 22 and does not receive resistance from the inner peripheral surface 22E to restrict rotation. Therefore, the support plate 26, cam plate 27, and shoes 28A, 28B rotate integrally with the rotation shaft 25A of the spindle gear 25.

[0054] 4, the pair of shoes 28A, 28B are locked to the protruding portions 27D, 27E of the pair of projections 27A, 27B of the cam plate 27 by the locking portions 28A4, 28B4. Therefore, centrifugal force generated by rotation in the pull-out direction β acts on the shoes 28A, 28B, preventing the shoes 28A, 28B from rotating in the centrifugal direction. As a result, during rotation in the pull-out direction β, the pair of shoes 28A, 28B can remain out of contact with the inner circumferential surface 22E of the cover 22, preventing rotational resistance caused by each shoe 28A, 28B.

[0055] Figure 5 is a diagram showing the positional relationship between the cam plate 27, shoes 28A and 28B, and inner circumferential surface 22E of the cover 22 of the winding speed suppression unit 20 according to the first embodiment when the spool 12 is rotating in the winding direction α. ​​The schematic configuration of Figure 5 is the same as that of Figure 4. Figure 5 shows the state when the winding speed suppression unit 20 is activated.

[0056] When the spool 12 is rotating in the winding direction α, the bush gear 23, which rotates integrally with the rotary shaft 13 of the spool 12, also rotates in the winding direction α. ​​Therefore, the spindle gear 25, to which power is transmitted via the bush gear 23 and the idle gear 24, also rotates in the winding direction α. ​​As a result, as shown in Figure 5, the rotary shaft 25A of the spindle gear 25 also rotates in the winding direction α.

[0057] Rotation shaft 25A of spindle gear 25 passes through through hole 26A of support plate 26 and is inserted into through hole 27C of cam plate 27, so cam plate 27 also receives the rotational driving force via through hole 27C. As a result, cam plate 27 rotates in conjunction with rotation shaft 25A relative to support plate 26 in the winding direction α.

[0058] When the spool 12 rotates in the winding direction α, the biasing force of the spiral spring 14 acts on the rotary shaft 13, so the rotation speed in the winding direction α tends to be relatively higher than the rotation speed in the unwinding direction β shown in Fig. 4. In addition, a group of gears including the spindle gear 25 is arranged as the speed-increasing gear 30 between the rotary shaft 13 of the retractor body 10 and the cam plate 27, so the rotation speed of the cam plate 27 in the winding direction α is faster than that of the rotary shaft 13.

[0059] As cam plate 27 rotates in this manner, paired projections 27A, 27B of cam plate 27 press contact surfaces 28A1, 28B1 of paired shoes 28A, 28B toward the centrifugal direction. As a result, when the centrifugal pressing force acting on each shoe 28A, 28B via contact surfaces 28A1, 28B1 becomes greater than the centrally biasing force acting on each shoe 28A, 28B from coil springs 29A, 29B, the pressing force causes each shoe 28A, 28B to rotate toward the centrifugal direction about pivot shafts 26C, 26D, as shown by arrow B in Fig. 5. As each shoe 28A, 28B continues to rotate toward the centrifugal direction, contact surfaces 28A1, 28B1 also move toward the centrifugal direction. As a result, paired projections 27A, 27B of cam plate 27 maintain contact with contact surfaces 28A1, 28B1, while further moving in winding direction α as their contact positions with contact surfaces 28A1, 28B1 move from the distal end toward the proximal end. As a result, while the cam plate 27 is rotating in the winding direction α, the shoes 28A and 28B can be constantly pressed toward the centrifugal side.

[0060] 5, the pair of shoes 28A, 28B rotate to a position where their outer peripheral surfaces 28A5, 28B5 come into contact with the inner peripheral surface 22E of the cover 22, and the frictional force generated by this contact creates resistance from the inner peripheral surface 22E that restricts rotation. This resistance force is transmitted to the spool 12 via the cam plate 27, the rotating shaft 25A of the spindle gear 25, and the speed-up gear 30, thereby suppressing the winding speed of the spool 12.

[0061] As described above, the seat belt retractor 3 according to the first embodiment includes a retraction speed suppression unit 20 that suppresses the rotation speed of the spool 12 in the retraction direction α. ​​The retraction speed suppression unit 20 includes a support plate 26, a cam plate 27 that is disposed on a main surface 26B side of the support plate 26, is rotatable in conjunction with the rotation shaft 13 of the spool 12, and is provided with protrusions 27A, 27B extending in the centrifugal direction from the center of rotation, shoes 28A, 28B that are connected to the support plate 26, are disposed on the centrifugal side of the cam plate 27 on the main surface 26B, and are provided with contact surfaces 28A1, 28B1 that are contactable with the protrusions 27A, 27B of the cam plate 27 on the central side, and an inner circumferential surface 22E of the cover 22 that serves as a restricting surface and is disposed on the centrifugal side of the shoes 28A, 28B.

[0062] With this configuration, when a relative rotation difference occurs between cam plate 27 and shoes 28A, 28B, protrusions 27A, 27B of cam plate 27 press contact surfaces 28A1, 28B1 of shoes 28A, 28B centrifugally. This pressing force causes shoes 28A, 28B to move centrifugally and come into contact with inner circumferential surface 22E of cover 22, which serves as the restricting surface. As a result, the frictional resistance in the rotational direction that shoes 28A, 28B receive from inner circumferential surface 22E provides resistance that restricts the rotation of cam plate 27 and rotating shaft 13 of spool 12, which moves in conjunction with cam plate 27, in winding direction α, thereby suppressing an increase in the winding speed of webbing 4 that occurs due to the biasing force of spiral spring 14. Furthermore, since the shoes 28A, 28B, which directly generate resistance, move toward the centrifugal side by the pressing force received from the cam plate 27 without using centrifugal force, the shoes 28A, 28B can be reliably moved toward the centrifugal side regardless of the weight of the shoes 28A, 28B themselves. Therefore, there is no need to increase the weight or size of the shoes 28A, 28B or other components. Therefore, according to this embodiment, it is possible to suppress an increase in the weight and size of the entire seat belt retractor 3, and to suppress an increase in the winding speed of the webbing 4.

[0063] Furthermore, in the seat belt retractor 3 according to the first embodiment, pivot shafts 26C and 26D are provided on the main surface 26B of the support plate 26, and are erected parallel to the axis CA. The shoes 28A and 28B are connected to the support plate 26 so as to be pivotable about the pivot shafts 26C and 26D, respectively, and when the contact surfaces 28A1 and 28B1 are pressed by the protrusions 27A and 27B of the cam plate 27, the shoes 28A and 28B pivot on the main surface 26B about the pivot shafts 26C and 26D, thereby moving centrifugally to a position where they come into contact with the inner circumferential surface 22E of the cover 22, which serves as a restricting surface.

[0064] With this configuration, when the contact surfaces 28A1, 28B1 of the shoes 28A, 28B are pressed by the projections 27A, 27B of the cam plate 27, the shoes 28A, 28B can be moved more smoothly toward the centrifugal side, and the shoes 28A, 28B can be brought into more reliable contact with the inner circumferential surface 22E to generate frictional resistance. This makes it possible to more reliably suppress an increase in the winding speed of the webbing 4.

[0065] In addition, in the seat belt retractor 3 according to the first embodiment, the winding speed suppression unit 20 has coil springs 29A, 29B that are connected between each shoe 28A, 28B and the main surface 26B of the support plate 26 and urge each shoe 28A, 28B toward the center.

[0066] With this configuration, when each shoe 28A, 28B transitions from a state in which it is pressed by the protrusions 27A, 27B of the cam plate 27 to a state in which it is not pressed, the biasing force of the coil springs 29A, 29B allows each shoe 28A, 28B to quickly move toward the axis CA, and quickly transition to a state in which it is not in contact with the inner peripheral surface 22E of the cover 22, which serves as the restricting surface. Furthermore, because the biasing force of the coil springs 29A, 29B is applied to the shoes 28A, 28B, it is possible to prevent each shoe 28A, 28B from moving toward the centrifugal side due to the action of centrifugal force, thereby preventing an unnecessary increase in frictional resistance and the occurrence of rotation restriction.

[0067] Furthermore, in the seat belt retractor 3 according to the first embodiment, each shoe 28A, 28B is provided with a locking portion 28A4, 28B4 at the end (i.e., the tip) of the contact surface 28A1, 28B1 that is opposite to the winding direction α and in the pull-out direction β in which the webbing 4 is pulled out from the spool 12, for locking with the protrusions 27A, 27B of the cam plate 27, respectively, thereby restricting the movement of each shoe 28A, 28B toward the centrifugal side.

[0068] 4, when the spool 12 is rotating in the unwinding direction β and the winding speed suppression unit 20 is to be kept in an inactive state, this configuration can suppress unnecessary contact between the shoes 28A, 28B and the inner peripheral surface 22E of the cover 22, which serves as the restricting surface, as a result of the shoes 28A, 28B moving toward the centrifugal side due to the action of centrifugal force. This prevents unnecessary operation of the winding speed suppression unit 20.

[0069] In addition, in the seat belt retractor 3 according to the first embodiment, a shaft (e.g., the rotating shaft 25A of the spindle gear 25) that is linked to the rotating shaft 13 of the spool 12 is inserted into the support plate 26, and an accelerating gear 30 that increases the rotational speed of the shaft relative to the rotating shaft 13 is provided between the rotating shaft 13 and the shaft.

[0070] With this configuration, the rotation speed of cam plate 27 of retraction speed suppression unit 20 can be increased relative to the rotation speed of spool 12 and rotary shaft 13, and therefore each of shoes 28A, 28B can be more quickly moved to the centrifugal side by the pressing of protrusions 27A, 27B of cam plate 27. This allows each of shoes 28A, 28B to more quickly come into contact with inner circumferential surface 22E of cover 22, which serves as a restricting surface, to generate frictional resistance, and more quickly suppression of an increase in the retraction speed of the webbing 4 can be exerted.

[0071] In the seat belt retractor 3 according to the first embodiment, the cam plate 27 has a pair of protrusions 27A, 27B that extend in opposite centrifugal directions from the center of rotation. The retraction speed suppression unit 20 has a pair of shoes 28A, 28B that are arranged such that their contact surfaces 28A1, 28B1 can come into contact with one of the pair of protrusions 27A, 27B and that the direction of movement due to pressure of the protrusions is opposite the centrifugal direction.

[0072] With this configuration, the contact points between the pair of shoes 28A, 28B and the inner surface 22E of the cover 22, which serves as the regulating surface, can be located at two points that are point-symmetrical with the axis CA as the center of symmetry, thereby enabling the winding speed suppression unit 20 to more stably exert its function of suppressing an increase in the winding speed of the webbing 4.

[0073] The features of the first embodiment can also be summarized as follows. In the first embodiment, due to the contact action between the pair of protrusions 27A, 27B of the cam plate 27 and the contact surfaces 28A1, 28B1 of the pair of shoes 28A, 28B, when the cam plate 27 rotates in the belt winding direction α, the shoes 28A, 28B rotate toward the inner circumferential surface 22E (cover inner circumferential wall) of the peripheral wall 22C of the cover 22 and press against the inner circumferential surface 22E. This generates resistance that reduces the rotational torque of the rotating shaft 13 in the belt winding direction α due to the spiral spring 14. On the other hand, when the rotating shaft 13 rotates in the belt unwinding direction β, which is opposite to the belt winding direction α, the pair of shoes 28A, 28B move away from the cover inner circumferential wall 22E, allowing each shoe 28A, 28B to rotate without receiving resistance.

[0074] Coil springs 29A, 29B are provided between the shoes 28A, 28B and the support plate 26, biasing the shoes 28A, 28B in a direction away from the cover inner peripheral wall 22E. When the cam plate 27 rotates in the belt winding direction α, the shoes 28A, 28B and the support plate 26 rotate in the same direction and integrally via the cam plate 27. Furthermore, when the load torque accelerating the rotation of the shoes 28A, 28B, which have a moment of inertia, and the support plate 26 exceeds the spring load of the coil springs 29A, 29B biasing the shoes 28A, 28B, the shoes 28A, 28B rotating together with the support plate 26 are pushed by the cam plate 27, causing them to rotate relatively on the support plate 26 and come into contact with the cover inner peripheral wall 22E. Then, as the shoes 28A and 28B are further pressed against the cover inner wall 22E, rotational resistance is generated between the support plate 26 and the shoes 28A and 28B, which generates a resistance torque in a direction that cancels out the torque of the spiral spring 14 that rotates the rotating shaft 13 of the spool 12 via the cam plate 27.

[0075] Even after shoes 28A, 28B are pressed against cover inner peripheral wall 22E, cam plate 27 continues to push shoes 28A, 28B, and support plate 26 in the winding direction α, resulting in a self-boosting effect among cam plate 27, shoes 28A, 28B, and cover inner peripheral wall 22E. As a result, the rotational resistance between shoes 28A, 28B, and support plate 26 is instantaneously amplified, causing the load torque to exceed the torque of spiral spring 14, which is the power driving rotation of rotating shaft 13 in the winding direction α, resulting in a sudden deceleration of the rotation of rotating shaft 13. This simultaneously means that the load exerted by cam plate 27 on shoes 28A, 28B is suddenly reduced, causing rotating shaft 13 to instantly accelerate again. This succession of instantaneous accelerations and decelerations results in the so-called speed-governing behavior.

[0076] A centrifugal governor mechanism, which is a typical speed-governing mechanism, operates when the angular velocity increases and the centrifugal force generated in the governor weight exceeds the biasing spring force. Therefore, to obtain a speed-governing effect equivalent to that of the first embodiment, it is necessary to increase the mass of the governor weight, or to position the center of gravity of the governor weight farther from the center of rotation, or both, which requires an increase in the weight and / or size of the product.

[0077] On the other hand, in the first embodiment, the load torque generated during acceleration by the moment of inertia of the support plate 26 and the shoes 28A, 28B is used as the power source for starting the rotation of the shoes 28A, 28B and for providing rotational resistance, rather than the centrifugal force of the shoes 28A, 28B, which corresponds to a centrifugal governor in the prior art. Furthermore, a powerful load can be generated instantaneously by exerting a self-boosting effect between the cam plate 27, the shoes 28A, 28B, and the cover inner peripheral wall 22E. Therefore, a transition to a speed-governing behavior can be made in a low speed range of the winding operation of the webbing 4, and as a result, stronger speed-governing control than the prior art can be achieved with a lightweight and compact configuration.

[0078] To enable the occupant 9 using the seat belt device 1 to feel the effectiveness of the speed-regulating mechanism of the retraction speed suppression unit 20 according to the first embodiment, it is necessary to obtain a large braking force instantaneously. This requires increasing the rotational moment of inertia of the shoes 28A, 28B and the support plate 26. In the first embodiment, the rotation of the cam plate 27, which is coupled to the rotation of the rotary shaft 13 and pushes the shoes 28A, 28B and the support plate 26 in the rotational direction, is amplified by the speed-up gear 30. This gear speed-up causes the moment of inertia of the shoes 28A, 28B and the support plate 26 to act at a rate equal to the square of the gear speed-up ratio, increasing the load torque with which the spiral spring 14 moves the shoes 28A, 28B and the support plate 26. This means that not only does this advance the timing at which the shoes 28A, 28B open, but the resistance torque, which is significantly amplified by the boosting effect generated in the shoes 28A, 28B pressed by the cam plate 27, further offsets the spiral spring torque by doubling the gear ratio.

[0079] As described above, the retraction speed suppression unit 20 according to the first embodiment has the effect of suppressing an increase in the retraction speed of the webbing 4. This effect reduces the speed at which the webbing 4 is stowed, thereby suppressing movement of metal fittings such as the tongue 7. Furthermore, this effect enables the webbing 4 to be retracted in a comfortable manner for the occupant 9 when the occupant 9, while wearing the seat belt, returns to the backrest of the seat 2 after leaning forward to unwind the webbing 4 (for example, to check left and right while driving). This is thought to be because, for example, the timing at which the webbing 4 is retracted is slightly delayed compared to the movement of the occupant 9 returning their upper body to the backrest, making it possible to gently fit the webbing 4 around the occupant 9.

[0080] [Modification of First Embodiment] A modification of the first embodiment will be described with reference to Figures 6 and 7. Figure 6 is a diagram showing the positional relationship between cam plate 27, shoes 28A and 28B, and inner circumferential surface 22E of cover 22 of winding speed suppression unit 20 according to the modification of the first embodiment when spool 12 is rotating in the unwinding direction β. Figure 7 is a diagram showing the positional relationship between cam plate 27, shoes 28A and 28B, and inner circumferential surface 22E of cover 22 of winding speed suppression unit 20 according to the modification of the first embodiment when spool 12 is rotating in the winding direction α. ​​Figures 6 and 7 correspond to Figures 4 and 5, respectively.

[0081] In the modified example shown in FIGS. 6 and 7 , the winding speed suppression unit 20 has a single wire spring 31 as a biasing member instead of the pair of coil springs 29A, 29B. The wire spring 31 in this modified example is a spring formed by processing a spring wire into an arc shape. The wire spring 31 is arranged to extend circumferentially around the axis CA of the support plate 26 and is disposed between the main surface 26B of the support plate 26 and the cam plate 27. One end 31A of the arc shape of the wire spring 31 is engaged with a groove 27F provided on the circumferential side surface of one protrusion 27B of the cam plate 27. The other end 31B of the wire spring 31 is engaged with a locking protrusion 26G formed to protrude from the main surface 26B of the support plate 26 in the X-positive direction. The locking protrusion 26G is located radially inward of the shoe 28B.

[0082] By being installed in this manner, the filigree spring 31 according to the modified example functions as a biasing member that biases the pair of shoes 28A, 28B toward the center, similar to the coil springs 29A, 29B of the above embodiment.

[0083] The wire spring 31 is preferably installed so as to be biased in a direction that increases the distance between the ends 31A, 31B. As a result, in the state shown in Fig. 6, the cam plate 27 receives a biasing force in the pull-out direction β and rotates in the pull-out direction β. This allows the pair of shoes 28A, 28B to remain locked to the protruding portions 27D, 27E of the pair of projections 27A, 27B of the cam plate 27 by the locking portions 28A4, 28B4. Therefore, as described with reference to Fig. 4, the centrifugal force generated by the rotation in the pull-out direction β acts on the shoes 28A, 28B, preventing the shoes 28A, 28B from rotating in the centrifugal direction.

[0084] On the other hand, in the state shown in Fig. 7, when the centrifugal pressing force received by each shoe 28A, 28B via the contact surfaces 28A1, 28B1 becomes greater than the urging force toward the center of the filigree spring 31, the pressing force causes the shoe 28A, 28B to rotate centrifugal toward the center about the pivot shafts 26C, 26D, as shown by arrow B in Fig. 7. As a result, as shown in Fig. 7, the pair of shoes 28A, 28B rotate to a position where their respective outer peripheral surfaces 28A5, 28B5 come into contact with the inner peripheral surface 22E of the cover 22, and the frictional force generated by this contact causes resistance from the inner peripheral surface 22E that restricts rotation.

[0085] Therefore, the configuration of the modified example can also achieve the same effects as those of the first embodiment. Furthermore, since the same effects as those of the pair of coil springs 29A, 29B of the first embodiment can be achieved using a single filigree spring 31, the number of parts in the winding speed suppression unit 20 can be reduced, improving manufacturing efficiency. Furthermore, in the configuration using a single filigree spring 31 as in the modified example, the spring force acts on three parts: the cam plate 27, the shoes 28A, 28B, and the support plate 26, so there is no play between the parts and there is no concern about noise.

[0086] Second Embodiment A second embodiment will be described with reference to FIGS.

[0087] Figure 8 is a perspective view showing the assembled state of each element of the main part of the winding speed suppression unit 120 according to the second embodiment. Figure 9 is a diagram showing the positional relationship between the cam plate 127, shoes 128A and 128B, and inner circumferential surface 22E of the cover 22 of the winding speed suppression unit 120 according to the second embodiment when the spool 12 is rotating in the unwinding direction β. Figure 10 is a diagram showing the positional relationship between the cam plate 127, shoes 128A and 128B, and inner circumferential surface 22E of the cover 22 of the winding speed suppression unit 120 according to the second embodiment when the spool 12 is rotating in the winding direction α. ​​The overviews of Figures 8 to 10 are the same as those of Figures 3 to 5, respectively.

[0088] The winding speed suppression unit 120 has, as elements to be accommodated in its internal space, in addition to the bush gear 23, idle gear 24, spindle gear 25, and support plate 26 (support member) described in the first embodiment, a cam plate 127 (rotating member), a pair of shoes 128A, 128B (resistance members), and a shoe spring 32 (biasing member), as shown in Figure 8.

[0089] The basic configuration of the cam plate 127 is similar to that of the cam plate 27 of the first embodiment. The pair of protrusions 127A, 127B and the through hole 127C of the cam plate 127 are similar in configuration to the pair of protrusions 27A, 27B and the through hole 27C of the first embodiment, respectively.

[0090] The pair of shoes 128A, 128B have the same basic configuration as the pair of shoes 28A, 28B of the first embodiment. The pair of shoes 128A, 128B have contact surfaces 128A1, 128B1, through holes 128A2, 128B2, and outer peripheral surfaces 128A5, 128B5 that are similar in configuration to the contact surfaces 28A1, 28B1, through holes 28A2, 28B2, and outer peripheral surfaces 28A5, 28B5 of the first embodiment, respectively.

[0091] On the other hand, the pair of shoes 128A, 128B according to the second embodiment do not have elements corresponding to the locking portions 28A4, 28B4 of the first embodiment at their ends in the pull-out direction β. As a result, unlike the first embodiment, the pair of protrusions 127A, 127B of the cam plate 127 can be arranged to face the base ends of the pair of shoes 128B, 128A, respectively, that is, the portions on the winding direction α side of the axes CC, CB, as shown in Figure 8.

[0092] The shoe spring 32 is an example of a biasing member that is connected between the pair of shoes 128A, 128B and biases the pair of shoes 128A, 128B toward the center (toward the axis CA). Similar to the wire spring 31 according to the modified example of the first embodiment, the shoe spring 32 is a spring formed by processing a spring wire into an arc shape. As shown in FIG. 8 , the shoe spring 32 is disposed between the main surface 26B of the support plate 26 and the cam plate 127 and the shoes 128A, 128B.

[0093] The shoe spring 32 has an elastically deforming portion 32A formed in an arc shape and connecting portions 32B, 32C provided at both ends of the elastically deforming portion 32A. The elastically deforming portion 32A is disposed along the main surface 26B of the support plate 26.

[0094] The connecting portions 32B, 32C are bent relative to the elastic deformation portion 32A so as to face in the normal direction (positive X direction) of the main surface 26B. As shown in FIG. 8 , one connecting portion 32B is inserted into a hole provided in one shoe 128A along the X direction, thereby connecting to one shoe 128A. Similarly, the other connecting portion 32C is inserted into a hole provided in the other shoe 128B along the X direction, thereby connecting to the other shoe 128B. In this way, the shoe spring 32 is connected between the pair of shoes 128A, 128B via the pair of connecting portions 32B, 32C.

[0095] Furthermore, the shoe spring 32 is preferably installed so that the arc-shaped elastic deformation portion 32A is biased in a direction that narrows the distance between the pair of connecting portions 32B, 32C, i.e., in a direction toward the axis CA. This allows the biasing force of the elastic deformation portion 32A to be applied to each shoe 128A, 128B via each connecting portion 32B, 32C, thereby preventing each shoe 128A, 128B from rotating in the centrifugal direction.

[0096] In the second embodiment, by connecting a single shoe spring 32 between the pair of shoes 128A and 128B, the force biasing each shoe 128A and 128B in the closing direction (i.e., toward the axis CA, as indicated by arrow A in Figure 9 and other figures) is always the same. Even if the load of the shoe spring 32 varies between components or changes over time, the attractive forces between the two components (i.e., the shoes 128A and 128B) can always remain equivalent. This allows the pair of shoes 128A and 128B to deploy due to centrifugal force (i.e., move in the centrifugal direction, as indicated by arrow B in Figure 10 and other figures) at the same timing, thereby avoiding "one-sided braking" when the shoes 128A and 128B contact the inner circumferential surface 22E of the cover 22 and exert braking force. "One-sided braking" refers to a situation in which only one of the pair of shoes 128A and 128B exerts braking force. In this way, with the configuration of the second embodiment, one side of the shoes 128A, 128B can be prevented from working unbalanced, and stable braking behavior can be obtained.

[0097] Furthermore, winding speed suppression unit 120 of the second embodiment has restricting portion 26H that restricts rotation of cam plate 127 in pull-out direction β. Restricting portion 26H is a cylindrical element that stands on main surface 26B of support plate 26, as shown in Fig. 8, for example. Restricting portion 26H is disposed on the rotation path of one projection 127B of cam plate 127 in the pull-out direction β, and restricts the rotation of cam plate 127 in the pull-out direction β by abutting against restricting portion 26H with abutting surface 127F, which is the surface of projection 127B that faces the pull-out direction β.

[0098] Furthermore, a pair of protrusions 127A, 127B of the cam plate 127 and the ends of the pair of shoes 128A, 128B in the winding direction α (base end side), which are surfaces facing each protrusion 127A, 127B, are provided with locking portions that lock each base end side end of each shoe 128A, 128B to each protrusion 127A, 127B of the cam plate 127 when rotation is restricted by the restricting portion 26H, thereby restricting the movement of each shoe 128A, 128B toward the centrifugal side. The specific configuration of the locking portion includes, for example, as shown in Figure 8, convex portions 127D, 127E that protrude from the surface of the pair of protrusions 127A, 127B of the cam plate 127 on the pull-out direction β side, and concave portions 128B3, 128A3 that are provided at each end on the base end side of each shoe 128B, 128A so that each convex portion 127D, 127E can engage with them.

[0099] 9, when the rotation of the spool 12 in the pull-out direction β causes the rotation shaft 25A of the spindle gear 25 to also rotate in the pull-out direction β, the cam plate 127 also receives a rotational driving force via the through hole 127C. As a result, the cam plate 127, in conjunction with the rotation shaft 25A, first rotates relative to the support plate 26 in the pull-out direction β.

[0100] Thereafter, abutment surface 127F provided on one projection 127B of cam plate 127 abuts against restriction portion 26H on main surface 26B of support plate 26. At this time, cam plate 127 and support plate 26 are connected to each other, and a rotational driving force is also transmitted to support plate 26. As a result, support plate 26 and a pair of shoes 128A, 128B mounted on support plate 26 also rotate in pull-out direction β.

[0101] At this time, the pair of shoes 128A, 128B are rotated toward the axis CA of the support plate 26 by the biasing force of the shoe spring 32, as shown by arrow A in FIG. 9 . As a result, the pair of shoes 128A, 128B are positioned radially at positions where their contact surfaces 128A1, 128B1 abut against the protrusions 127A, 127B of the cam plate 127. In this state, the outer peripheral surfaces 128A5, 128B5 of the shoes 128A, 128B are positioned closer to the center than the outer edge of the disc-shaped support plate 26. Therefore, the shoes 128A, 128B are not in contact with the inner peripheral surface 22E of the cover 22 and do not receive resistance from the inner peripheral surface 22E to restrict rotation. Therefore, the support plate 26, the cam plate 127, and the shoes 128A, 128B rotate integrally with the rotation shaft 25A of the spindle gear 25.

[0102] 9, cam plate 127 maintains a state in which abutment surface 127F abuts against restriction portion 26H of support plate 26, so cam plate 127 always rotates integrally with support plate 26. On the other hand, pair of shoes 128A, 128B are not in contact with cam plate 127, so that centrifugal force generated by rotation in pull-out direction β acts on shoes 128A, 128B, which may cause shoes 128A, 128B to rotate in the centrifugal direction relative to support plate 26.

[0103] However, in the configuration of the second embodiment, even if such shoes 128A, 128B rotate in the centrifugal direction, recesses 128A3, 128B3 on the base end sides of each shoe 128A, 128B abut against protrusions 127E, 127D of cam plate 127, respectively. Thereafter, further rotation of each shoe 128A, 128B in the centrifugal direction is restricted by cam plate 127, which rotates integrally with support plate 26. In other words, the locking portions (protrusions 127E, 127D, recesses 128A3, 128B3) provided on cam plate 127 and each shoe 128A, 128B more reliably maintain a state in which the pair of shoes 128A, 128B are not in contact with inner circumferential surface 22E of cover 22 during rotation in pull-out direction β, thereby preventing rotational resistance caused by each shoe 128A, 128B.

[0104] 10, when the rotation of the spool 12 in the winding direction α causes the rotation shaft 25A of the spindle gear 25 to also rotate in the winding direction α, the cam plate 127 also receives a rotational driving force via the through hole 127C. As a result, the cam plate 127, in conjunction with the rotation shaft 25A, first rotates relative to the support plate 26 in the winding direction α.

[0105] This rotation of cam plate 127 causes a pair of protrusions 127A, 127B of cam plate 127 to press contact surfaces 128A1, 128B1 of a pair of shoes 128A, 128B centrifugally. When the centrifugal pressing force received by contact surfaces 128A1, 128B1 becomes greater than the centrally biasing force received from shoe spring 32, each shoe 128A, 128B rotates centrifugally about pivot shafts 26C, 26D due to the pressing force, as shown by arrow B in FIG. 10 . As each shoe 128A, 128B continues to rotate toward the centrifugal side, contact surfaces 128A1, 128B1 also move toward the centrifugal side, so that the pair of protrusions 127A, 127B of cam plate 127 maintains contact with contact surfaces 128A1, 128B1 while moving their contact positions with contact surfaces 128A1, 128B1 from the distal end toward the proximal end, further moving in winding direction α. ​​This allows shoes 128A, 128B to be constantly pressed toward the centrifugal side while cam plate 127 is rotating in winding direction α.

[0106] 10, the pair of shoes 128A, 128B rotate to a position where their outer peripheral surfaces 128A5, 128B5 come into contact with the inner peripheral surface 22E of the cover 22, and the frictional force generated by this contact creates resistance from the inner peripheral surface 22E that restricts rotation. This resistance force is transmitted to the spool 12 via the cam plate 127, the rotating shaft 25A of the spindle gear 25, and the speed-up gear 30, thereby suppressing the winding speed of the spool 12.

[0107] In the configuration of the second embodiment, cam plate 127 can separate the positions of the portion associated with the function of opening shoes 128A, 128B in the centrifugal direction (contact portions between protrusions 127A, 127B of cam plate 127 and contact surfaces 128A1, 128B1 of shoes 128A, 128B) and the portion associated with the function of restricting the opening of shoes 128A, 128B (engagement portions including convex portions 127D, 127E of cam plate 127 and concave portions 128B3, 128A3 of shoes 128B, 128A). This allows the shapes of the portions of the outer circumferential surfaces of protrusions 127A, 127B of cam plate 127 that come into contact with contact surfaces 128A1, 128B1 of shoes 128A, 128B in the restricted state of shoes 128A, 128B shown in FIG. 9 to be the same as the shapes of contact surfaces 128A1, 128B1. As a result, when the spool 12 switches between winding and unwinding directions, i.e., when the rotation direction of the cam plate 127 switches between the winding direction α and the unwinding direction β, the relative movement of the cam plate 127 with respect to each shoe 128A, 128B can be made smoother.

[0108] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples made by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements of the above-described specific examples, as well as their arrangement, conditions, shape, etc., are not limited to those exemplified and can be modified as appropriate. The elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise.

[0109] In the above embodiment, the winding speed suppression unit 20 has a pair of shoes 28A, 28B, but it may have only a single shoe as long as it has an element that at least restricts rotation in the winding direction α. ​​In this case, the cam plate 27 may also have a single protrusion that can press the single shoe toward the centrifugal side, rather than a pair of protrusions 27A, 27B.

[0110] In the above embodiment, a configuration has been exemplified in which the speed-up gear 30 for increasing the rotation speed of the rotating shaft 13 is provided between the rotating shaft 13 of the retractor body 10 and the cam plate 27 of the winding speed suppression unit 20, but a configuration without the speed-up gear 30 may also be used. In this case, the rotating shaft 13 of the retractor body 10 is directly connected to the through-hole 27C of the cam plate 27. That is, in the above embodiment, the rotating shaft 25A of the spindle gear 25 of the speed-up gear 30 corresponds to the "shaft member" inserted into the through-hole 26A provided in the center of the support plate 26. On the other hand, in a configuration without the speed-up gear 30, the rotating shaft 13 of the retractor body 10 corresponds to this "shaft member."

[0111] In the above embodiment, the shoes 28A, 28B are connected to the support plate 26 on the main surface 26B, are disposed on the centrifugal side of the cam plate 27 on the main surface 26B, and have contact surfaces 28A1, 28B1 on the central side that can come into contact with the protrusions 27A, 27B of the cam plate 27. However, the arrangement of the shoes 28A, 28B is not limited to this. For example, the cam plate 27 may be disposed on the main surface 26B side of the support plate 26, while the shoes 28A, 28B may be movably connected to the centrifugal side on a main surface that is disposed on the opposite side of the main surface 26B of the support plate 26 (the negative X direction side in FIG. 2 , etc.). In this case, the contact surfaces 28A1, 28B1 of the shoes 28A, 28B are formed to extend toward the main surface 26B through the radial outside of the support plate 26 and be able to come into contact with the protrusions 27A, 27B of the cam plate 27, respectively.

[0112] This international application claims priority based on Japanese Patent Application No. 2024-072071, filed on April 26, 2024, the entire contents of which are incorporated herein by reference.

[0113] REFERENCE SIGNS LIST 1 seat belt device 3 seat belt retractor 4 webbing 7 tongue 8 buckle 12 spool 13 rotating shaft (shaft member) 14 spiral spring (biasing portion) 20, 120 winding speed suppressing portion 22E inner peripheral surface (regulating surface) 25A spindle gear rotating shaft (shaft member) 26 support plate (support member) 26A through hole 26B main surface on the X positive direction side 26C, 26D rotating shaft 26H restricting portion 27, 127 cam plate (rotating member) 27A, 27B, 127A, 127B protrusion 28A, 28B, 128A, 128B shoe (resistance member) 28A1, 28B1, 128A1, 128B1 contact surface 28A4, 28B4 engaging portion 29A, 29B Coil spring (biasing member) 30 Speed-up gear 31 Wire spring (biasing member) 32 Shoe spring (biasing member) 127D, 127E Convex portion (locking portion) 127F Abutment surface 128A3, 128B3 Concave portion (locking portion) α Winding direction β Pulling direction

Claims

1. A device comprising: a spool around which webbing is wound; a biasing unit that biases the spool in a winding direction in which the spool winds the webbing; and a winding speed suppressing unit that suppresses the rotation speed of the spool in the winding direction caused by the biasing of the biasing unit, wherein the winding speed suppressing unit has: a plate-shaped support member that is inserted into a hole at the center of which a shaft member including a rotation axis of the spool or an axis interlocking with the rotation axis, and has a main surface on the side where the tip of the shaft member is inserted; a rotating member that is arranged on the main surface side of the support member and is connected to be rotatable in conjunction with the tip of the shaft member that protrudes from the hole to the main surface side, and has a protrusion that extends in a centrifugal direction from the rotation center; a resistance member that is connected to the support member, is arranged on the centrifugal side of the rotating member, and has a contact surface that can come into contact with the protrusion of the rotating member; and a regulating surface that is arranged on the centrifugal side of the support member and extends in the rotation direction of the support member. a contact surface of the resistance member that is formed so as to be pressed by the protrusion of the rotating member in accordance with a change in the relative positional relationship between the protrusion of the rotating member and the resistance member along the rotational direction when the spool rotates in the winding direction, thereby moving the resistance member centrifugally to a position where it comes into contact with the regulating surface; and a winding speed suppressing unit that suppresses the rotational speed of the spool in the winding direction by contact between the resistance member and the regulating surface.

2. A seat belt retractor as set forth in claim 1, wherein the resistance member is connected to the support member on the main surface, is positioned on the centrifugal side of the rotating member on the main surface, and has the contact surface that can come into contact with the protrusion of the rotating member on the central side.

3. A seat belt retractor as set forth in claim 2, wherein a rotating shaft is provided on the main surface of the support member, standing parallel to the shaft member, and the resistance member is connected to the support member so as to be rotatable about the rotating shaft, and when the contact surface is pressed by the protrusion of the rotating member, the resistance member rotates on the main surface about the rotating shaft, thereby moving centrifugally to a position where it comes into contact with the regulating surface.

4. A seat belt retractor according to claim 1, wherein the winding speed suppressing section has a biasing member connected between the resistance member and the main surface of the support member, and biasing the resistance member toward the center.

5. A seat belt retractor as set forth in claim 1, wherein the resistance member is provided with a locking portion at an end of the contact surface in the direction opposite to the winding direction and in the withdrawal direction in which the webbing is withdrawn from the spool, for locking the protrusion of the rotating member and restricting movement of the resistance member toward the centrifugal side.

6. A seat belt retractor according to claim 1, wherein the retraction speed suppressing section has a pair of the resistance members, and a biasing member connected between the pair of resistance members to bias the pair of resistance members toward the center.

7. A seat belt retractor as set forth in claim 6, wherein the winding speed suppressing section has a restricting section that restricts rotation of the rotating member in a pull-out direction that is opposite to the winding direction and in which the webbing is pulled out from the spool, and the protrusion of the rotating member and the end of the resistance member in the winding direction that faces the protrusion are provided with a locking section that locks the end of the resistance member to the protrusion of the rotating member in a state in which rotation is restricted by the restricting section, thereby restricting movement of the resistance member towards the centrifugal side.

8. A seat belt retractor as claimed in claim 1, wherein the shaft that moves in conjunction with the rotary shaft is inserted into the support member, and an accelerating gear that increases the rotational speed of the shaft relative to the rotary shaft is provided between the rotary shaft and the shaft.

9. A seat belt retractor as claimed in claim 1, wherein the rotating member has a pair of protrusions each extending from the center of rotation in opposite directions in the centrifugal direction, and the winding speed suppressing section has a pair of resistance members each of whose contact surfaces can come into contact with one of the pair of protrusions and which are installed so that the direction of movement due to pressure from the protrusions is opposite to the centrifugal direction.

10. A seat belt device comprising: a webbing for restraining an occupant; a seat belt retractor as claimed in claim 1 which winds up the webbing so that it can be withdrawn and which is activated in an emergency to prevent the webbing from being withdrawn; a tongue which is slidably supported on the webbing withdrawn from the seat belt retractor; and a buckle which is provided on a vehicle body or a seat and to which the tongue is releasably engaged.

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