Energy absorption device and seat belt device

Abstract

This energy absorption device comprises: an energy absorption mechanism for absorbing and mitigating energy of an occupant by limiting a load applied to a webbing for restraining the occupant; a final-strength-holding part for holding a final strength after the operation of the energy absorption mechanism; a cable for connecting the energy absorption mechanism to a buckle, which is the transmission source of the load; and a wire for connecting the final-strength-holding part to the buckle.

Description

Energy absorption device and seat belt device

[0001] The present disclosure relates to an energy absorbing device and a seat belt device.

[0002] In conventional seat belt devices equipped in automobiles and other vehicles, in an emergency such as when a large vehicle deceleration occurs during a collision while the seat belt (webbing) is fastened, the locking means of the seat belt retractor is activated to prevent the spool from rotating in the webbing withdrawal direction, thereby restraining the occupant with the webbing and preventing the occupant from jumping out of the seat.

[0003] In this conventional seat belt device, when the seat belt retractor restrains the occupant with the webbing in an emergency such as a vehicle collision, vehicle deceleration occurs, causing the occupant to move forward due to inertia. This applies a load to the webbing and causes the occupant to receive energy from the webbing. It is desirable to limit this energy to the occupant as much as possible.

[0004] Therefore, a configuration has been proposed in the past in which an energy absorption device (hereinafter also referred to as an EA device) is provided in the buckle to limit the load on the webbing in an emergency when the webbing is attached, and absorb and mitigate the energy applied to the occupant from the webbing (for example, Patent Document 1).

[0005] The conventional EA device for a buckle disclosed in Patent Document 1 has a spool that is rotatably supported with respect to the vehicle seat on the vehicle lower side of the buckle and around which the other longitudinal end of the webbing is wound, and a torsion shaft (energy absorbing member) that is deformed by the rotation of the spool.

[0006] Japanese Patent Application Laid-Open No. 2020-125010

[0007] In the conventional EA device for a buckle disclosed in Patent Document 1, the ultimate strength is maintained by a transmission member attached to the energy absorbing member. Therefore, the EA device, including the energy absorbing member, is subjected to a load exceeding a predetermined EA load, and the EA device must be able to withstand such loads. To meet this requirement, the EA device must be made more rigid than necessary for the desired energy absorption performance, for example by increasing the size or weight of the EA device.

[0008] An object of the present disclosure is to provide an energy absorption device and a seat belt device that can maintain ultimate strength while suppressing increases in size and weight.

[0009] An energy absorption device according to one aspect of an embodiment of the present invention includes an energy absorption mechanism that limits the load applied to a webbing that restrains an occupant and absorbs and alleviates the energy of the occupant, a final strength retention unit that maintains final strength after activation of the energy absorption mechanism, a first connecting unit that connects the energy absorption mechanism to a component that guides or restrains the webbing, which is the source of the load, and a second connecting unit that connects the final strength retention unit to the component.

[0010] According to the present disclosure, it is possible to provide an energy absorbing device and a seat belt device that can maintain ultimate strength while suppressing an increase in size and weight.

[0011] 1 is a structural diagram of a seat belt device to which an energy absorption (EA) device according to the first embodiment is applied; FIG. 2 is a perspective view of a buckle to which the EA device according to the first embodiment is applied; FIG. 3 is an exploded perspective view of the EA device shown in FIG. 2; FIG. 4 is a cross-sectional view taken along line A-A in FIG. 2; FIG. 5 is a perspective view showing a state in which the EA mechanism of the EA device according to the first embodiment is in operation; FIG. 6 is a perspective view showing a state after the EA mechanism of the EA device according to the first embodiment has been activated; FIG. 7 is a diagram showing the arrangement of the curved portion of the wire in the state shown in FIG.

[0012] 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.

[0013] In the following description, the X, Y, and Z directions are perpendicular to one another. Typically, the X and Y directions are horizontal, and the Z direction is vertical. The X direction is the longitudinal direction of the vehicle when the energy absorption (EA) device 1 is installed in the vehicle, with the negative X direction side being the front of the vehicle and the positive X direction side being the rear of the vehicle. The Y direction is the width direction of the vehicle when the EA device 1 is installed in the vehicle. For ease of explanation, the positive Z direction side may also be referred to as the upper side and the negative Z direction side as the lower side.

[0014] First Embodiment A first embodiment will be described with reference to FIGS.

[0015] FIG. 1 is a configuration diagram of a seat belt apparatus 10 to which an energy absorption (EA) device 1 according to a first embodiment is applied. As shown in FIG. 1 , the seat belt apparatus 10 includes a webbing 11 (seat belt) for restraining an occupant that is unwound from a retractor 12. The retractor 12 is a device for winding up the webbing 11 and is fixed to a lower portion of a center pillar 13 inside the vehicle cabin. Note that although the retractor 12 is shown by a solid line in FIG. 1 , in reality, the retractor 12 is housed inside the center pillar 13. The webbing 11 unwound from the retractor 12 toward the upper side of the vehicle body is inserted into a guide anchor 14 attached to the upper portion of the center pillar 13 and folded back toward the lower side of the vehicle body. The leading end of the webbing 11 is fixed to a belt anchor 16 provided between the center pillar 13 and a seat 15.

[0016] A tongue 17 is provided in the webbing 11 at a portion between the guide anchor 14 and the belt anchor 16 so that the webbing 11 can be inserted therethrough. The tongue 17 is attached to and detached from a buckle 18 that is disposed on the opposite side of the seat 15 from the belt anchor 16. In other words, the buckle 18 releasably fastens the tongue 17, which is slidably supported on the webbing 11 that restrains the occupant.

[0017] Fig. 2 is a perspective view of a buckle 18 to which the EA device 1 according to the first embodiment is applied. Fig. 3 is an exploded perspective view of the EA device 1 shown in Fig. 2. Fig. 4 is a cross-sectional view taken along line A-A in Fig. 2, showing a cross-sectional view of the vicinity of the torsion bar 22 in the EA mechanism 2 before activation. In the first embodiment, a configuration in which the EA device 1 is applied to the buckle 18 in a seat belt device 10 will be described as an example.

[0018] As shown in Figures 1 and 2, the buckle 18 is equipped with an energy absorption (EA) device 1. The EA device 1 is a device in a vehicle seat belt device 10 that is activated in an emergency, such as a vehicle collision, to limit the load on the webbing 11 when the webbing is fastened, thereby absorbing and mitigating the energy applied to the occupant from the webbing 11. The EA device 1 is fixed to the vehicle body and connected to the buckle 18 via a cable 4 (first connecting portion) and a wire 5 (second connecting portion). The EA device 1 also functions as a base for the buckle 18. Figures 1 and 2 show the EA device 1 in a state prior to activation.

[0019] 2 and 3 , the EA device 1 includes an energy absorption (EA) mechanism 2. The EA mechanism 2 is an element that exhibits the energy absorption performance of the EA device 1, and is activated in an emergency such as a vehicle collision to limit the load on the webbing 11 that restrains the occupant when the webbing is attached, thereby absorbing and mitigating the energy of the occupant. The EA device 1 of the first embodiment also includes a final strength retention unit 3 that is an element separate from the EA mechanism 2. The final strength retention unit 3 is an element that maintains the final strength after the EA mechanism 2 is activated.

[0020] The EA mechanism 2 and the final strength retaining unit 3 are connected to the buckle 18 via separate systems, a first connecting unit and a second connecting unit, respectively. A long cable 4 serving as the first connecting unit connects the EA mechanism 2 to the buckle 18, which is the source of load transmission. As shown in Figures 2 and 3, in this embodiment, the cable 4 is a single long member made of any material, such as metal or resin, and one end 4A of the cable 4 is connected to the buckle 18.

[0021] The wire 5 as the second connecting portion connects the final strength retaining portion 3 to the buckle 18. As shown in Figures 2 and 3, in this embodiment, the wire 5 is a single long member made of any material, such as metal or resin, and has both ends 5B and 5C connected to the buckle 18 to form a U-shape.

[0022] 2 and 3 , both ends 5B, 5C of the wire 5 are crimped and fixed to the ferrule 9 by crimping portions 91 disposed at the bottom of the ferrule 9 so that they are positioned approximately in the Z direction and extend along the Z direction at approximately the same distance in the X direction. Also, one end 4A of the cable 4 is crimped and fixed to the ferrule 9 by the crimping portion 91 of the ferrule 9 at an intermediate position in the X direction between both ends 5B, 5C of the wire 5 so that it extends along the Z direction like both ends 5B, 5C of the wire 5. In other words, the ferrule 9 crimps and fixes a total of three elongated members, namely, both ends 5B, 5C of the wire 5 and one end 4A of the cable 4, together with the crimping portions 91.

[0023] 2 and 3 , the ferrule 9 is connected to the buckle 18 by a connecting portion 92 disposed at an upper portion thereof. That is, the cable 4 and the wire 5 are connected to the buckle 18 via the ferrule 9. As a result, the load applied to the webbing 11 is transmitted to the cable 4 and the wire 5 via the buckle 18.

[0024] A cable end 6 having a larger diameter than the cable 4 is attached to the outer periphery of one end 4A of the cable 4. As shown in FIG. 2 , one end 4A of the cable 4 is fixed to the ferrule 9 so that the cable end 6 is positioned above the upper end of the crimped portion 91. When a load is applied to the buckle 18 from the webbing 11, the buckle 18 receives a load that pulls it upward in FIG. 2 , and this load is transmitted to the cable 4 via the connection portion between the ferrule 9 and the crimped portion 91 (see arrow B in FIG. 5 and arrow D in FIG. 6 ). At this time, because the cable end 6 is located above the crimped portion 91, even if the crimping of the crimped portion 91 is insufficient and the cable 4 can move relative to the crimped portion 91, the cable end 6 is caught on the upper end of the crimped portion 91, preventing the cable 4 from coming off the ferrule 9. This prevents the EA mechanism 2 from failing to exhibit its energy absorption performance.

[0025] The EA mechanism 2 and final strength maintainer 3 are both mounted on a plate-shaped base 8. In the example of Figures 2 and 3, the base 8 is, for example, a flat plate-shaped member arranged with its main surface facing the Y direction, and is fixedly mounted on the vehicle body. The elements of the EA mechanism 2 and final strength maintainer 3 are mounted on one main surface 81 of the base 8 facing the positive Y direction. In the example of Figures 2 and 3, the EA mechanism 2 and final strength maintainer 3 are arranged in series along the Z direction, with the EA mechanism 2 positioned above and the final strength maintainer 3 positioned below.

[0026] The EA mechanism 2 has a spool 21 and a torsion bar 22. As shown in FIG. 3 , the spool 21 is a hollow cylindrical member, and is disposed so that its axis is parallel to the X-axis. The cable 4 is wound around the spool 21. In the example of the pre-activation state shown in FIGS. 2 and 3 , the wound portion 4B of the cable 4 wound around the spool 21 is wound around the outer circumferential surface 21A of the spool 21 approximately three times in the circumferential direction.

[0027] The torsion bar 22 is a rod-shaped member with a circular cross section as shown in Fig. 3, and is arranged so that its axis direction is parallel to the X-axis. The torsion bar 22 is inserted through the spool 21 so as to be coaxial with the spool 21 as shown by the axis L in Figs. 3 and 4, and is connected to the spool 21, and is configured to be able to torsionally deform when a predetermined energy absorption load is applied.

[0028] Here, the connecting structure between the spool 21 and the torsion bar 22 will be described with reference to FIG.

[0029] 2 to 4, four support plates 23, 24, 25, and 26 are provided on the upper part of the base 8, i.e., the part where the EA mechanism 2 is attached, standing on the Y-positive side from the main surface 81. The four support plates 23 to 26 are arranged in this order from the X-negative side to the X-positive side. The support plates 23 to 26 are also arranged facing each other along the X-direction, with the X-direction being their main surfaces. The main surfaces of the support plates 23 to 26 have substantially the same shape, and as shown in FIG. 3, for example, the tip end is semicircular so that the width in the Z-direction decreases from the base end connected to the base 8 toward the tip end in the X-positive direction.

[0030] Of the four support plates 23 to 26, two support plates 24, 25 located in the center in the X direction are provided with circular through-holes 24A, 25A, respectively. Both through-holes 24A, 25A are formed so that their centers are on axis L. The through-holes 24A, 25A have approximately the same diameter and are both larger than the outer diameter of the spool 21, allowing the spool 21 to be inserted therethrough and to rotate about axis L. As shown in FIGS. 2 and 4 , the spool 21 is inserted through the through-holes 24A, 25A and supported by the two support plates 24, 25.

[0031] Of the four support plates 23 to 26, support plate 23, which is positioned furthest in the negative X direction, and support plate 26, which is positioned furthest in the positive X direction, are provided with polygonal through holes 23A and 26A, respectively. Similar to through holes 24A and 25A, through holes 23A and 26A are also formed so that their centers are on axis L. Through hole 23A is formed so that its opening area is larger than that of through hole 26A.

[0032] 3 and 4, the torsion bar 22 has a central shaft 22A formed with approximately the same diameter along the X direction, and flanges 22B, 22C, 22D, and 22E provided at four locations along the X direction of the central shaft 22A so as to protrude radially outward from the outer circumferential surface of the central shaft 22A. The four flanges 22B to 22E are arranged on the central shaft 22A in this order from the negative X direction side to the positive X direction side.

[0033] Each of the flanges 22B to 22E is formed so that its outer shape when viewed from the X direction is polygonal. The outer shape of the flange 22B located furthest in the X negative direction is the same shape as the through-hole 23A of the support plate 23, and the flange 22B is formed so that it can fit into the through-hole 23A. The outer shape of the flange 22E located furthest in the X positive direction is the same shape as the through-hole 26A of the support plate 26, and the flange 22E is formed so that it can fit into the through-hole 26A.

[0034] The flange 22B is provided at the end of the central shaft 22A on the X-negative side. A circular flange 22F, which is larger than the outer shape of the flange 22B, is provided on the X-negative end surface of the flange 22B. By providing the flange 22B and the circular flange 22F in this manner, when the torsion bar 22 is inserted into the through-hole 23A from the X-negative side of the support plate 23, the flange 22B finally fits into the through-hole 23A, and the circular flange 22F is engaged with the main surface of the support plate 23 on the X-negative side. As a result, the torsion bar 22 is positioned on the base 8 at a position where the flange 22B fits into the through-hole 23A, preventing the torsion bar 22 from moving further in the X-positive direction and coming off the base 8. The torsion bar 22 is connected to the base 8 at the fitting portion between the flange 22B and the through-hole 23A so as not to rotate about the axis L relative to the base 8.

[0035] With the flange 22B positioned at the position of the support plate 23 as described above, the flange 22E is disposed at a position where it fits into the through-hole 26A of the support plate 26. Therefore, the torsion bar 22 is connected to the base 8 so as not to rotate around the axis L, even at the fitting portion between the flange 22E and the through-hole 26A.

[0036] The spool 21 also has an insertion hole 21B formed along the axis L. A torsion bar 22 is inserted through the insertion hole 21B. The insertion hole 21B is formed so that the inner circumferential surface thereof has a polygonal shape when viewed from the X direction. Of the four flanges 22B to 22E, the two flanges 22C and 22D located in the center in the X direction have the same outer shape as the insertion hole 21B of the spool 21, and the flanges 22C and 22D are formed so as to be able to fit into the insertion hole 21B. The flanges 22C and 22D are positioned so as to fit into the insertion hole 21B of the spool 21 when the flange 22B is positioned at the position of the support plate 23 as described above.

[0037] As a result, the torsion bar 22 is connected to the spool 21 at the engagement portions between the flanges 22C, 22D and the insertion hole 21B so as not to rotate relative to the spool 21 around the axis L. As shown in Figure 4, the positions of the flanges 22C, 22D in the X direction are preferably arranged in the same positions as the support plates 24, 25, respectively, in this state.

[0038] Furthermore, with the flange 22B positioned at the position of the support plate 23 as described above, a push nut 27 having a diameter larger than the diameter of the central shaft 22A and the through hole 26A of the support plate 26 is attached to the outer periphery of the portion of the central shaft 22A that protrudes in the X positive direction beyond the support plate 26. By attaching the push nut 27 to the torsion bar 22 in this manner, it is possible to prevent the torsion bar 22 from slipping out in the X negative direction from the state in which the flange 22B is positioned at the position of the support plate 23.

[0039] In this manner, the torsion bar 22 is connected to the base 8 side, i.e., the vehicle body side, by the two flanges 22B and 22E, and is connected to the spool 21 side by the other two flanges 22C and 22D.

[0040] Furthermore, a through hole 21C is provided in the outer peripheral surface 21A of the spool 21, radially passing through the axis L. Similarly, a through hole 22G is provided in the central shaft 22A of the torsion bar 22, radially passing through the axis L. When the flange 22B is positioned at the position of the support plate 23, the through hole 21C of the spool 21 and the through hole 22G of the torsion bar 22 are arranged at the same position in the X direction, allowing them to be coaxially superimposed. The other end 4C of the cable 4 is inserted through these through holes 21C and 22G. A cable end 7, which has a diameter larger than that of the cable 4, is attached to the outer periphery of the other end 4C of the cable 4, which passes through the through holes 21C and 22G and protrudes from the outer peripheral surface 21A of the spool 21. As a result, even when the EA mechanism 2 is activated and the cable 4 is pulled, the cable end 7 is caught on the outer peripheral surface 21A of the spool 21, so that the other end 4C of the cable 4 can be prevented from coming off the spool 21 or the torsion bar 22.

[0041] Next, a description will be given of the configuration of the final strength maintaining part 3. In addition to the wire 5 described above, the final strength maintaining part 3 has a fastening bolt 31 (fixing part), a bracket 32, and a pulley 33.

[0042] The bracket 32 ​​is a member formed to be connectable to the lower part of the base 8. The bracket 32 ​​is formed in a convex shape with a central portion bulging toward the Y-positive direction, so that an internal space can be formed between the bracket 32 ​​and the base 8 when attached to the base 8. The bracket 32 ​​can accommodate the wire 5 in this internal space. An opening 32A is formed in the negative-side portion of the bracket 32, which opens toward the Z-positive direction when attached to the base 8. On the other hand, an opening 32B is formed in the X-positive side portion of the bracket 32, which opens toward the X-positive direction when attached to the base 8. The wire 5 extends from the opening 32A along the Z direction at the X-positive side of the bracket 32 ​​and exits to the outside, and from the opening 32B along the X direction at the X-positive side of the bracket 32 ​​and exits to the outside. In other words, the bracket 32 ​​functions as a guide that guides the extension direction of the wire 5 to change from the X direction to the Z direction.

[0043] Furthermore, a circular through-hole 32C is provided in the bracket 32. Meanwhile, a circular through-hole 34 similar to the through-hole 32C is also provided in the base 8. The through-holes 32C and 34 are provided in positions that overlap when viewed from the Y direction when the bracket 32 ​​is attached to the base 8, and both have coaxial axial directions that are parallel to the Y direction, and are provided so that the opening areas are approximately the same.

[0044] Pulley 33 is a cylindrical member, and the outer shape of peripheral wall 33A is formed with a diameter that allows it to fit into through-hole 32C and through-hole 34. As a result, when installed, pulley 33 is arranged so that its central axis is parallel to the Y direction and coaxial with through-hole 32C and through-hole 34. A circular flange 33B with a larger diameter than the cylindrical peripheral wall 33A of pulley 33 is provided on the end of pulley 33 on the through-hole 32C side, and flange 33B is engaged with the surface of bracket 32, thereby preventing pulley 33 from slipping out of through-hole 34 in the negative Y direction.

[0045] Fastening bolt 31 is a fixing element that fastens and fixes EA device 1 to the vehicle body. The diameter of shaft 31A of fastening bolt 31 is formed to be approximately the same as the inner diameter of pulley 33 and is formed so that it can be inserted into pulley 33. Fastening bolt 31 is inserted into pulley 33 from the Y positive side, with shaft 31A protruding from base 8 toward the Y negative side, and is fastened to the vehicle body by a threaded portion provided on shaft 31A protruding from base 8 toward the Y negative side. In addition, head 31B of fastening bolt 31 is disposed in contact with the Y positive side of bracket 32, thereby preventing EA device 1 from slipping out in the Y positive direction.

[0046] In particular, in this embodiment, when the EA device 1 is installed, the fastening bolt 31 is installed so as to pass inside the U-shape of the wire 5. The fastening bolt 31 is located between both ends 5B, 5C of the wire 5 that are located on the buckle 18 side and the curved portion 5A that is curved in a U-shape and located at the end of the wire 5 opposite both ends 5B, 5C in the extension direction of the wire 5. In other words, the wire 5 is formed in a loop shape on the outer periphery of the fastening bolt 31, and both ends 5B, 5B are connected to the buckle 18 via the ferrule 9. Therefore, when the wire 5 is pulled out together with the cable 4 toward the buckle 18 during operation of the EA mechanism 2, the portion between the curved portion 5A and one end 5B and the portion between the curved portion 5A and the other end 5C move parallel to each other at positions sandwiching the fastening bolt 31. As a result, the curved portion 5A of the wire 5 is ultimately locked along the fastening bolt 31, more specifically, the peripheral wall of the pulley 33 through which the fastening bolt 31 is inserted (see FIG. 7), thereby restricting further movement of the wire 5 toward the buckle 18. The final strength retaining portion 3 can retain the final strength by locking the curved portion 5A of the wire 5 to the fastening bolt 31.

[0047] 3, the final strength retaining portion 3 may be configured to include a heat-shrink tube 35. For example, as shown in FIG. 3, the heat-shrink tube 35 is inserted into the curved portion 5A of the wire 5 from the positive X-direction side, and is installed at a position from the curved portion 5A to the fastening bolt 31 and the pulley 33. As described above, the portion of the wire 5 to which the heat-shrink tube 35 is attached is arranged such that the portion between the curved portion 5A and one end 5B and the portion between the curved portion 5A and the other end 5C are arranged substantially parallel to each other with the fastening bolt 31 sandwiched between them.

[0048] Before being attached to the wire 5, the heat-shrinkable tube 35 is formed in a cylindrical shape with a diameter sufficiently large relative to the Z-direction and Y-direction dimensions of the bending portion 5A, for example, to facilitate insertion of the wire 5. The heat-shrinkable tube 35 is heated after the wire 5 is inserted, thereby shrinking in diameter and being attached to the wire 5 so as to be in close contact with and surround the portion between the bending portion 5A and one end 5B and the portion between the bending portion 5A and the other end 5C of the wire 5. With this configuration, the heat-shrinkable tube 35 can maintain the portion between the bending portion 5A and one end 5B and the portion between the bending portion 5A and the other end 5C in a substantially parallel arrangement across the fastening bolt 31, even when the wire 5 moves toward the buckle 18 in conjunction with the activation of the EA mechanism 2.

[0049] When the curved portion 5A of the wire 5 moves to the position of the fastening bolt 31 and pulley 33 during operation of the EA mechanism 2 (see FIGS. 5 to 7), the heat-shrinkable tube 35 can naturally come off the wire 5 as the wire 5 moves, for example, by hitting against the peripheral wall of the pulley 33. This prevents the heat-shrinkable tube 35 from interfering with the movement of the wire 5 toward the buckle 18.

[0050] Next, the operation of the EA device 1 of the first embodiment will be described with reference to Figs. 5 to 7 in addition to Fig. 2. Fig. 2 is a perspective view of the buckle 18 to which the EA device 1 of the first embodiment is applied, as described above, and is a perspective view showing a state before the EA mechanism 2 of the EA device 1 is activated. Fig. 5 is a perspective view showing a state during activation of the EA mechanism 2 of the EA device 1 of the first embodiment. Fig. 6 is a perspective view showing a state after activation of the EA mechanism 2 of the EA device 1 of the first embodiment. Fig. 7 is a diagram showing the arrangement of the curved portion 5A of the wire 5 in the state shown in Fig. 6.

[0051] 2, before the EA mechanism 2 is activated, the lower end of the ferrule 9 is located at the upper end of the base 8. At this time, the wound portion 4B of the cable 4 is wound approximately three times around the outer peripheral surface 21A of the spool 21. In addition, most of the curved portion 5A side of the wire 5 is disposed so as to protrude from the opening 32B of the bracket 32 ​​in the positive X direction.

[0052] Next, if an excessive load is applied to the webbing 11 in an emergency, such as a vehicle collision, this load is transmitted to the torsion bar 22 via the buckle 18, the ferrule 9, the cable 4, and the spool 21. When a load exceeding a predetermined energy absorption load is transmitted, the torsion bar 22 is torsionally deformed about the axis L. As a result, the spool 21, whose rotation has been restricted by the torsion bar 22, rotates about the axis L, and the cable 4 is pulled out from the wound portion 4B toward the buckle 18. As a result, the buckle 18 moves in the direction of load transmission as shown by arrow B in Fig. 5. At this time, both ends 5B and 5C of the wire 5 connected to the ferrule 9 are also pulled out in the load transmission direction together with the end 4A of the cable 4. Accordingly, due to this pulling-out movement, the portion of the wire 5 on the curved portion 5A side also moves toward the bracket 32 ​​as shown by arrow C in Fig. 5.

[0053] Then, as shown by arrow D in Fig. 6, the EA mechanism 2 continues to operate, moving the buckle 18 in the load transmission direction, and as shown by arrow E, the curved portion 5A of the wire 5 is pulled into the bracket 32, and finally, as shown in Fig. 7, the curved portion 5A is locked by the fastening bolt 31. This prevents the wire 5 from being pulled out any further in the load transmission direction, and the load is received by the fixed portion to the vehicle body, such as the fastening bolt 31, via the curved portion 5A of the wire. As a result, the final strength retention portion 3 of the EA device 1 can maintain the final strength.

[0054] As described above, the EA device 1 according to the first embodiment includes an energy absorption mechanism (EA mechanism) 2 that limits the load applied to the webbing 11 that restrains the occupant and absorbs and alleviates the energy of the occupant, a final strength retention unit 3 that retains the final strength after the EA mechanism 2 is activated, a cable 4 that connects the EA mechanism 2 to the buckle 18 that is the source of the load transmission, and a wire 5 that connects the final strength retention unit 3 to the buckle 18.

[0055] With this configuration, the EA mechanism 2 and the ultimate strength retainer 3 can be connected to the buckle 18 via separate systems, namely, the cable 4 as the first connecting part and the wire 5 as the second connecting part. As a result, after the EA mechanism 2 receives a predetermined energy absorption load and is activated, the ultimate strength can be maintained by the ultimate strength retainer 3, eliminating the need for the EA mechanism 2 to maintain its ultimate strength. Therefore, the EA mechanism 2 does not need to be configured to retain a load exceeding the energy absorption load. Therefore, it is not necessary to increase the rigidity of the EA mechanism 2 beyond what is necessary for the desired energy absorption performance, for example, by increasing its size or weight. Furthermore, because the ultimate strength retainer 3 is connected to the buckle 18 via a system separate from the EA mechanism 2, the structure can be simplified without relying on the structure of the EA mechanism 2. As a result, the EA device 1 according to the first embodiment can maintain its ultimate strength while suppressing an increase in the size and weight of the entire device.

[0056] Furthermore, in the EA device 1 according to the first embodiment, the second connecting portion is a wire 5 having both ends 5B, 5C connected to the buckle 18 and formed into a U-shape. The final strength retaining portion 3 has a fastening bolt 31 as a fixing portion that is fixed to the vehicle body, and is installed by inserting the fastening bolt 31 into the inside of the U-shape of the wire 5. When the energy absorption mechanism 2 is activated, the wire 5 is pulled out toward the buckle 18 together with the first connecting portion (cable 4), and the final strength retaining portion 3 retains the final strength by engaging the fastening bolt 31 with the U-shaped curved portion 5A of the wire 5 on the opposite side from the buckle 18.

[0057] With this configuration, the final strength retaining section 3 can retain the final strength with a simple structure that uses a single wire 5 as the second connecting section and a fastening bolt 31 as the fixing section, thereby further suppressing an increase in the size and weight of the entire EA device 1.

[0058] In the EA device 1 according to the first embodiment, the first connecting part is a long cable 4. The energy absorption mechanism 2 has a spool 21 around which the cable 4 is wound, and a torsion bar 22 that is inserted through the spool 21 so as to be coaxial with the spool 21 and connected to the spool 21, and that is capable of torsional deformation when a predetermined energy absorption load is applied.

[0059] 4 and other figures, this configuration allows the torsion bar 22 to be arranged coaxially with the spool 21 and to be arranged so as to overlap the spool 21 in the axial direction, thereby further suppressing increases in size and weight of the energy absorption mechanism 2. Furthermore, since the cable 4 is used as the first connecting part, the load transmitted from the buckle 18 can be transmitted to the spool 21 efficiently, allowing the energy absorption mechanism 2 to operate with precision.

[0060] Second Embodiment A second embodiment will be described with reference to FIGS.

[0061] Fig. 8 is a perspective view of a buckle 18 to which an EA device 1A according to the second embodiment is applied. Fig. 9 is an exploded perspective view of the EA device 1A shown in Fig. 8. Fig. 10 is a cross-sectional view taken along the line K-K in Fig. 8. In the second embodiment, as in the first embodiment, an example will be described in which the EA device 1A is applied to a buckle 18 in a seat belt device 10.

[0062] 8 and 9 , the EA device 1A includes an energy absorption (EA) mechanism 102. The EA mechanism 102 is an element that exhibits the energy absorption performance of the EA device 1A, and is activated in an emergency such as a vehicle collision to limit the load applied to the webbing 11 that restrains the occupant when the webbing is attached, thereby absorbing and mitigating the energy of the occupant. The EA device 1A of the second embodiment also includes a final strength retention unit 103 that is an element separate from the EA mechanism 102. The final strength retention unit 103 is an element that maintains final strength after the EA mechanism 102 is activated.

[0063] The EA mechanism 102 and the final strength retaining unit 103 are connected to the buckle 18 via separate systems, a first connecting unit and a second connecting unit, respectively. A long cable 104 serving as the first connecting unit connects the EA mechanism 102 to the buckle 18, which is the source of load transmission. As shown in Figures 8 and 9, in this embodiment, the cable 104 is a single long member made of any material, such as metal or resin, and a U-shaped portion 104A formed by curving the central portion in the longitudinal direction is connected to the buckle 18 via an insertion hole 19B of the connecting member 19.

[0064] The wire 105 as the second connecting portion connects the final strength retaining portion 103 to the buckle 18. As shown in Figures 8 and 9, in the second embodiment, the wire 105 is a single long member made of any material, for example, metal or resin, and has a U-shaped portion 105A formed by curving the central portion in the longitudinal direction, which is connected to the buckle 18 via the peripheral surface 19A of the connecting member 19.

[0065] The connecting member 19 is a plate-like member having a thickness in the Y direction. Two insertion holes 19B are provided in the lower portion of the negative Z direction side of the connecting member 19, aligned along the X direction at the same position in the Z direction, and penetrating in the Y direction. As shown in FIG. 8 and other figures, the cable 104 is inserted into the two insertion holes 19B on both sides of the U-shaped portion 104A of the cable 104 so that the U-shaped portion 104A of the cable 104 is positioned further to the negative Y direction side than the connecting member 19. As a result, the U-shaped portion 104A of the cable 104 is hooked onto the portion of the connecting member 19 between the two insertion holes 19B, and the cable 104 is connected to the buckle 18.

[0066] A side surface of the plate-shaped connecting member 19, which has a constant thickness, functions as a peripheral surface 19A of the connecting member 19. The peripheral surface 19A protrudes in the Z positive direction at the upper end of the upper portion of the Z positive direction side of the connecting member 19 and is formed to have a substantially semicircular shape when viewed in the Y direction. The U-shaped portion 105A of the wire 105 is disposed in contact with the peripheral surface 19A along the arc-shaped upper end portion of the peripheral surface 19A of the connecting member 19. As a result, the U-shaped portion 105A of the wire 105 is hooked onto the peripheral surface 19A of the connecting member 19, and as a result, the wire 105 is connected to the buckle 18 in a slidable manner along the peripheral surface 19A.

[0067] The connecting member 19 is connected and fixed to the buckle 18 at an upper portion on the Z positive side. As a result, the load applied to the webbing 11 is transmitted to the cable 104 and the wire 105 via the buckle 18 and the connecting member 19.

[0068] The EA mechanism 102 and the final strength retaining unit 103 are both mounted on a plate-shaped base 108. In the example shown in FIGS. 8 and 9 , the base 108 is, for example, a flat plate-shaped member arranged with its main surface facing the Y direction, and is fixedly mounted on the vehicle body. The elements of the EA mechanism 102 are mounted on one main surface 181 of the base 108 facing the Y positive direction. On the other hand, the elements of the final strength retaining unit 103 (except for the head 131B of the bolt 131) are arranged on the opposite side of the main surface 181 and mounted on the other main surface facing the Y negative direction.

[0069] The EA mechanism 102 includes a torsion bar 121 , an axial shaft 122 , and a spool 123 .

[0070] As shown in FIG. 9 , the spool 123 is a hollow cylindrical member and is disposed so that its axis is parallel to the X-axis. The cable 104 is wound around the spool 123. In the example of the pre-activation state shown in FIGS. 8 and 9 , two winding portions 104B and 104C of the cable 104 wound around the spool 123 are wound circumferentially for approximately three turns around two grooves 123B and 123C formed along the circumferential direction on the outer circumferential surface 123A of the spool 123. The two winding portions 104B and 104C are located on the X-negative and X-positive sides, respectively, of the central U-shaped portion 104A of the cable 104. The grooves 123B and 123C are each formed in a spiral shape from the center toward the edge in the axial direction of the outer circumferential surface 123A of the spool 123. As a result, the portion of the cable 104 that is closest to the U-shaped portion 104A of the winding portions 104B and 104C is positioned toward the center of the outer circumferential surface 123A, and by winding the winding portions 104B and 104C along the grooves 123B and 123C, the portions of the cable 104 that are closest to the ends 104D and 104E of the cable 104 are positioned toward the edges of the outer circumferential surface 123A. In addition, an insertion hole 123F is formed in the spool 123 so as to pass through the spool 123 along the X-axis direction.

[0071] As shown in Figure 9, the shaft 122 is a hollow cylindrical member and is disposed so that its axis is parallel to the X-axis. The outer diameter of the shaft 122 is smaller than the inner diameter of the insertion hole 123F of the spool 123. The shaft 122 is inserted through the insertion hole 123F of the spool 123 so as to be coaxial with the spool 123, as indicated by the axis L in Figures 9 and 10. An engaging protrusion 122C is formed on the outer peripheral surface 122B of the shaft 122 so as to protrude from the outer peripheral surface 122B. Meanwhile, an engaging recess 123G is formed on the inner peripheral surface of the insertion hole 123F of the spool 123 so as to be recessed from the inner peripheral surface. The engaging protrusion 122C and the engaging recess 123G have substantially the same cross-sectional shape perpendicular to the X-axis, so that the engaging protrusion 122C is fitted into the engaging recess 123G when the shaft 122 is inserted into the insertion hole 123F of the spool 123. As a result, the shaft 122 is coupled to the spool 123 via the engaging protrusion 122C and the engaging recess 123G so as to be rotatable together with the spool 123. In addition, the shaft 122 is provided with an insertion hole 122A that penetrates along the X-axis direction.

[0072] As shown in FIG. 9 , the torsion bar 121 is a rod-shaped member with a circular cross section, and is disposed so that its axis is parallel to the X-axis. The outer diameter of the central axis 121A of the torsion bar 121 is smaller than the inner diameter of the insertion hole 122A of the shaft 122. The torsion bar 121 is inserted into the insertion hole 122A of the shaft 122 so as to be coaxial with the spool 123 and the shaft 122, as indicated by the axis L in FIGS. 9 and 10 . A polygonal flange 121C is formed at the center of the X-direction on the outer circumferential surface of the central axis 121A of the torsion bar 121, protruding radially outward from the outer circumferential surface. Meanwhile, as shown in FIG. 10 , an engagement portion 122D into which the flange 121C can be fitted is formed at the center of the X-direction on the inner circumferential surface of the insertion hole 122A of the shaft 122. When the torsion bar 121 is inserted into the insertion hole 122A of the axial shaft 122, the flange 121C of the torsion bar 121 engages with the engaging portion 122D of the axial shaft 122, and as a result, the torsion bar 121 is connected to the axial shaft 122 via the flange 121C and the engaging portion 122D so as to be rotatable together with the axial shaft 122. In other words, the torsion bar 121 is also connected to the spool 123 via the axial shaft 122 so as to be rotatable together with the spool 123. This allows the torsion bar 121 to be torsionally deformed when a predetermined energy absorption load is applied to the spool 123.

[0073] As shown in Figures 8 to 10, four support plates 124, 125, 126, and 127 are provided on the upper part of the base 108, i.e., the part where the EA mechanism 102 is attached, standing on the Y-positive side from the main surface 181. The four support plates 124 to 127 are arranged in this order from the X-negative side to the X-positive side. The support plates 124 to 127 are also arranged facing each other along the X-direction, with their main surfaces all facing the X-direction. The main surfaces of the support plates 124 to 127 have substantially the same shape, and as shown in Figure 9, for example, the tip end is substantially semicircular so that the width in the Z-direction decreases from the base end connected to the base 108 toward the tip end on the X-positive side.

[0074] Of the four support plates 124 to 127, two support plates 125, 126 located in the center in the X direction are provided with circular through-holes 125A, 126A, respectively. Both through-holes 125A, 126A are formed so that their centers are on axis L. The through-holes 125A, 126A have approximately the same diameter and are both larger than the outer diameter of the shaft 122, allowing the shaft 122 to be inserted therethrough and to rotate about axis L. As shown in Figures 8 and 10 , the shaft 122 is inserted through the through-holes 125A, 126A and supported by the two support plates 125, 126.

[0075] The distance in the X direction between the two support plates 125, 126 is set to be greater than the length of the spool 123 in the X direction. The diameters of the through holes 125A, 126A are both formed to be smaller than the outer diameter of the spool 123. As a result, as shown in Figures 8 and 10, the spool 123 is disposed between the two support plates 125, 126, and the movement of the spool 123 in the X direction is restricted to within the range of the two support plates 125, 126.

[0076] Of the four support plates 124 to 127, support plate 124, which is positioned furthest in the negative X direction, and support plate 127, which is positioned furthest in the positive X direction, are provided with polygonal through-holes 124A and 127A, respectively. Similar to through-holes 125A and 126A, through-holes 124A and 127A are also formed so that their centers are on axis L. Through-hole 124A is formed so that its opening area is larger than that of through-hole 127A.

[0077] 9 and 10, the torsion bar 121 has a central shaft 121A formed with approximately the same diameter along the X direction, and flanges 121B, 121C, and 121D provided at three locations in the X direction of the central shaft 121A so as to protrude radially outward from the outer circumferential surface of the central shaft. The three flanges 121B to 121D are arranged on the central shaft 121A in this order from the negative X direction side to the positive X direction side. As described above, the flange 121C is arranged in approximately the center of the axial direction (X direction) of the central shaft 121A.

[0078] Each of the flanges 121B to 121D is formed so that its outer shape when viewed from the X direction is polygonal. The outer shape of the flange 121B arranged furthest in the X negative direction is the same shape as the through-hole 124A of the support plate 124, and the flange 121B is formed so that it can fit into the through-hole 124A. The outer shape of the flange 121D arranged furthest in the X positive direction is the same shape as the through-hole 127A of the support plate 127, and the flange 121D is formed so that it can fit into the through-hole 127A.

[0079] The flange 121B is provided at the end of the central shaft 121A on the X-negative side. A circular flange 121E, which is larger than the outer shape of the flange 121B, is provided on the X-negative end face of the flange 121B. By providing the flange 121B and the circular flange 121E in this manner, when the torsion bar 121 is inserted into the through-hole 124A from the X-negative side of the support plate 124, the flange 121B finally fits into the through-hole 124A, and the circular flange 121E is locked onto the main surface of the support plate 124 on the X-negative side. As a result, the torsion bar 121 is positioned on the base 108 at a position where the flange 121B fits into the through-hole 124A, preventing the torsion bar 121 from moving further in the X-negative direction and coming off the base 108. The torsion bar 121 is connected to the base 108 at the engagement portion between the flange 121B and the through-hole 124A so as not to rotate around the axis L relative to the base 108.

[0080] With the flange 121B positioned at the position of the support plate 124 as described above, the flange 121D is disposed at a position where it fits into the through-hole 127A of the support plate 127. Therefore, the torsion bar 121 is connected to the base 108 so as not to rotate around the axis L, even at the fitting portion between the flange 121D and the through-hole 127A.

[0081] Furthermore, with the flange 121B positioned at the position of the support plate 124 as described above, a push nut 128 having a diameter larger than the diameter of the central shaft 121A and the through hole 127A of the support plate 127 is attached to the outer periphery of the portion of the central shaft 121A that protrudes in the X positive direction beyond the support plate 127. By attaching the push nut 128 to the torsion bar 121 in this manner, it is possible to prevent the torsion bar 121 from slipping out in the X negative direction from a state in which the flange 121B is positioned at the position of the support plate 124.

[0082] In this way, the torsion bar 121 is connected to the base 108 side, i.e., the vehicle body side, by the two flanges 121B and 121D, and is connected to the spool 123 side via the shaft 122 by the other flange 121C.

[0083] Two cable ends 123D and 123E are provided on the outer peripheral surface 123A of the spool 123. One cable end 123D is located on the negative X-axis side of the groove 123B. The other cable end 123E is located on the positive X-axis side of the groove 123C. One end 104D, which extends from one winding portion 104B toward the opposite side of the U-shaped portion 104A, is inserted into and fixed to one cable end 123D. The other end 104E, which extends from the other winding portion 104C toward the opposite side of the U-shaped portion 104A, is inserted into and fixed to the other cable end 123E.

[0084] Next, a description will be given of the configuration of the final strength retention part 103. In addition to the wire 105 described above, the final strength retention part 103 has a fastening bolt 131 (fixing part), a bracket 132, and a pulley 133.

[0085] 9, pulley 133 is a cylindrical member. Pulley 133 is disposed so that the axis of the cylindrical hole faces the Y direction, and stepped surfaces 133B and 133C are formed by recessing radially inward at both ends of cylindrical outer wall 133A on the Y negative and Y positive sides, respectively.

[0086] Meanwhile, a circular hole 136 is provided in base 108 below support plates 124 to 127, penetrating the base in the Y direction. The outer diameter of step surface 133C on the Y positive side of pulley 133 is formed to be substantially the same as the inner diameter of circular hole 136 in base 108. As a result, step surface 133C is fitted into circular hole 136 from the Y negative side, and the end face of the step surface on the Y negative side abuts against the main surface of base 108 opposite main surface 181, thereby engaging pulley 133 with the Y negative side of base 108.

[0087] 9, bracket 132 is a flat plate-shaped member that is bent at a substantially right angle at a predetermined position in the Z direction. That is, bracket 132 has a vertical portion 132A that is disposed so that its main surface faces the Y direction, and a horizontal portion 132B that is bent from the upper end of vertical portion 132A toward the Y positive direction and is disposed so that its main surface faces the Z direction.

[0088] The vertical portion 132A of the bracket 132 is disposed on the Y negative side of the base 108 and the pulley 133. A circular hole 132C is formed through the vertical portion 132A in the Y direction. The outer diameter of the stepped surface 133B on the Y negative side of the pulley 133 is formed to be substantially the same as the inner diameter of the circular hole 132C of the bracket 132. As a result, the stepped surface 133B is fitted into the circular hole 132C from the Y positive side, and the end face of the stepped surface on the Y positive side abuts against the main surface on the Y positive side of the vertical portion 132A of the bracket 132, thereby engaging the bracket 132 with the Y negative side of the pulley 133. As a result, the bracket 132 is also connected to the base 108 via the pulley 133.

[0089] 8 and 9, a cover 134 is provided on the Y positive side of the base 108 and covers the entire base 108. The cover 134 has a first portion 134A that covers the upper portion of the base 108 where the support plates 124 to 127 are provided, and a second portion 134B that is disposed opposite the main surface 181 of the base 108 below the support plates 124 to 127. The second portion 134B is formed in a flat plate shape facing the Y direction. The first portion 134A protrudes in the Y positive direction relative to the second portion 134B and is formed to be able to accommodate the support plates 124 to 127 of the base 108, which are substantially semicircular in shape. A circular hole 134C is formed in the second portion 134B so as to penetrate in the Y direction. The circular hole 134C is provided so as to be coaxial with the circular hole 136 of the base 108.

[0090] The circular hole 134C of the cover 134, the circular hole 136 of the base 108, the cylindrical hole of the pulley 133, and the circular hole 132C of the bracket 132 form a through hole whose axial direction is in the Y direction.

[0091] The fastening bolt 131 is a fixing element that fastens and fixes the EA device 1A to the vehicle body. The diameter of the shaft 131A of the fastening bolt 131 is approximately the same as the inner diameter of the pulley 133 and is formed so that it can be inserted through the pulley 133. The fastening bolt 131 is inserted from the Y positive side through the circular hole 134C of the cover 134, the circular hole 136 of the base 108, and the pulley 133 via the washer 135. The shaft 131A protrudes in the Y negative direction from the circular hole 132C of the bracket 132, and is fastened to the vehicle body by a threaded portion provided on the shaft 131A protruding in the Y negative direction from the vertical portion 132A of the bracket 132. The head 131B of the fastening bolt 131 is disposed in contact with the Y positive side of the bracket 132, thereby preventing the EA device 1A from slipping out in the Y positive direction.

[0092] In the second embodiment, when the EA device 1A is installed, the fastening bolt 131 is installed so as to pass through the inside of the U-shape of the wire 105. The fastening bolt 131 is located between the U-shaped portion 105A of the wire 105 that is located on the buckle 18 side and a pair of end portions 105B, 105C that extend on both sides of the U-shaped portion 105A and are located on the opposite side of the U-shaped portion 105A. The wire 105 on one end portion 105B side is located on the positive Z direction side of the fastening bolt 131, and the wire 105 on the other end portion 105C side is located on the negative Z direction side of the fastening bolt 131.

[0093] The pair of end portions 105B, 105C are disposed on the X-positive side of the position of fastening bolt 131 of EA device 1A. One end portion 105B is disposed on the Z-positive side of the other end portion 105C. In other words, wire 105 is formed such that two ends on either side of U-shaped portion 105A at the upper end extend toward the Z-negative side from U-shaped portion 105A, bend toward the X-positive side at the position of fastening bolt 131, and then extend toward the X-positive side. As described above, wire 105 is installed slidably along circumferential surface 19A of connecting member 19, and therefore U-shaped portion 105A is any portion of the intermediate portion of wire 105 that comes into contact with circumferential surface 19A of connecting member 19.

[0094] 8 and 9, both ends 105B and 105C of wire 105 are disposed so as to extend along the X direction at approximately the same distance in the Z direction. Wire ends 105D and 105E, which are larger in diameter than wire 105, are attached to the outer peripheries of both ends 105B and 105C of wire 105, respectively.

[0095] 9 , two insertion holes 132D and 132E are formed in the horizontal portion 132B of the bracket 132, penetrating in the Z direction. The diameters of the insertion holes 132D and 132E are larger than the diameter of the wire 105 and smaller than the diameters of the wire ends 105D and 105E. One insertion hole 132D is located on the positive X-direction side of the horizontal portion 132B, and the other insertion hole 132E is located on the negative X-direction side of the horizontal portion 132B. When the EA device 1A is installed, the horizontal portion 132B of the bracket 132 is located above the Z-direction positions of the fastening bolt 131 and the pulley 133 and below the U-shaped portion 105A of the wire 105. The wire 105 on one end 105B side is inserted through one of the insertion holes 132D of the bracket 132. The other end 105C of the wire 105 is inserted into the other insertion hole 132E of the bracket 132.

[0096] 8 and 9, the connecting member 19 and the portion of the wire 105 wound around the connecting member 19 are covered by a spacer 20. The spacer 20 is provided with an insertion hole 20A that penetrates in the Z direction, and the connecting member 19 and the wire 105 are inserted through the insertion hole 20A.

[0097] Furthermore, a notch 20B is formed in a downward recess in the center of the upper end of the spacer 20. The lower end of the notch 20B is formed to be lower in the Z direction than the two insertion holes 19B of the connecting member 19 when the EA device 1A is installed, as shown in Figure 8. As a result, when the EA device 1A is installed, the two insertion holes 19B of the connecting member 19 are exposed from the notch 20B of the spacer 20, allowing the cable 104 to be inserted therethrough.

[0098] Next, the operation of the EA device 1A according to the second embodiment will be described with reference to FIGS. 11 to 14 in addition to FIG. 8 . FIG. 11 is a perspective view showing the EA mechanism 102 of the EA device 1A before activation. The state shown in FIG. 11 is similar to that shown in FIG. 8 , except that a cover 134 is attached to cover the EA mechanism 102 and a portion of the final strength retaining unit 103. FIG. 12 is a perspective view showing the EA mechanism 102 of the EA device 1A according to the second embodiment during activation. FIG. 13 is a perspective view showing the EA mechanism 102 of the EA device 1A according to the second embodiment after activation. FIG. 14 is a diagram showing the arrangement of the ends 105B and 105C of the wire 105 in the state shown in FIG. 13 . FIG. 14 is an enlarged perspective view of the vicinity of the base 108 in the state shown in FIG. 13 , viewed from the negative Y direction (the rear side of FIG. 13 ).

[0099] Before the EA mechanism 102 is activated, the lower end of the spacer 20 is located at the upper end of the pulley 133 of the final strength maintaining unit 103, and therefore the buckle 18 is located near the upper end of the EA mechanism 102. At this time, as shown in Fig. 8, the wound portions 104B and 104C of the cable 104 are wound around the outer peripheral surface 123A of the spool 123 by approximately three turns. Also, as shown in Fig. 11, most of the ends 105B and 105C of the wire 105 are located so as to protrude in the positive X direction from the main body (portion covered by the cover 134) of the EA mechanism 102 and the final strength maintaining unit 103.

[0100] Next, if an excessive load is applied to the webbing 11 in an emergency such as a vehicle collision, this load is transmitted to the torsion bar 121 via the buckle 18, the connecting member 19, the cable 104, the spool 123, and the shaft 122. When a load exceeding a predetermined energy absorption load is transmitted, the torsion bar 121 is torsionally deformed about the axis L. As a result, the shaft 122 and the spool 123, whose rotation has been restricted by the torsion bar 121, rotate about the axis L, and the cable 104 is pulled out from the winding portions 104B and 104C toward the buckle 18. As a result, the buckle 18 moves in the direction of transmission of the load, as shown by arrow F in FIG. At this time, the U-shaped portion 105A of the wire 105 wound around the connecting member 19 is also pulled out in the direction of load transmission together with the U-shaped portion 104A of the cable 104 connected to the connecting member 19. Accordingly, with this pulling-out operation, the portions of the wire 105 on the ends 105B and 105C side also move toward the main body (negative X direction side) of the EA mechanism 102 and the final strength holding unit 103, as shown by arrow G in Figure 12.

[0101] Then, as shown by arrow H in Figure 13, the EA mechanism 2 continues to operate, moving the buckle 18 in the load transmission direction, and the ends 105B and 105C of the wire 105 are retracted into the EA mechanism 102 and the main body of the final strength retaining unit 103. At this time, as shown in Figure 14, the wire ends 105D and 105E finally abut against the horizontal portion 132B of the bracket 132, and both ends 105B and 105C of the wire 105 are locked by the horizontal portion 132B of the bracket 132. This prevents the wire 105 from being pulled out further in the load transmission direction, and the load is received by the fixed parts to the vehicle body, such as the bracket 132, via both ends 105B and 105C of the wire 105 and the wire ends 105D and 105E. As a result, the final strength retaining unit 103 of the EA device 1A can retain the final strength.

[0102] As described above, the EA device 1A according to the second embodiment includes an energy absorption mechanism (EA mechanism) 102 that limits the load applied to the webbing 11 that restrains the occupant and absorbs and alleviates the energy of the occupant, a final strength holding unit 103 that holds the final strength after the EA mechanism 102 is activated, a cable 104 that connects the EA mechanism 102 to the buckle 18 that is the source of the load transmission, and a wire 105 that connects the final strength holding unit 103 to the buckle 18.

[0103] With this configuration, the EA mechanism 102 and the ultimate strength retaining unit 103 can be connected to the buckle 18 via separate systems, namely, the cable 104 as the first connecting unit and the wire 105 as the second connecting unit. As a result, after the EA mechanism 102 receives a predetermined energy absorption load and operates, the ultimate strength can be maintained by the ultimate strength retaining unit 103, eliminating the need for the EA mechanism 102 to maintain its ultimate strength. Therefore, the EA mechanism 102 does not need to be configured to retain a load exceeding the energy absorption load. Therefore, it is not necessary to increase the rigidity of the EA mechanism 102 beyond what is necessary for the desired energy absorption performance, for example, by increasing its size or weight. Furthermore, because the ultimate strength retaining unit 103 is connected to the buckle 18 via a system separate from the EA mechanism 102, the structure can be simplified without relying on the structure of the EA mechanism 102. As a result, the EA device 1A according to the second embodiment can maintain its ultimate strength while suppressing an increase in the size and weight of the entire device.

[0104] In the EA device 1A according to the second embodiment, the first connecting portion is a long cable 104. A U-shaped portion 104A formed by bending a central portion of the cable 104 is connected to the buckle 18, and a load applied to the webbing 11 that restrains the occupant can be transmitted to the cable 104 via the U-shaped portion 104A. The energy absorption mechanism 102 includes a spool 123 around which both end portions 104D, 104E of the cable 104 are fixed by winding portions of the cable 104 on both sides of the U-shaped portion 104A (i.e., a winding portion 104B included in the portion on the end 104D side and a winding portion 104C included in the portion on the end 104E side), and a torsion bar 121 that is inserted coaxially with the spool 123, connected to the spool 123 and also connected to the vehicle body, and that is capable of torsional deformation when a predetermined energy absorption load is applied.

[0105] 10 and other figures, this configuration allows the torsion bar 121 to be disposed coaxially with the spool 123 and to be disposed so as to overlap the spool 123 in the axial direction, thereby further suppressing an increase in the size and weight of the energy absorption mechanism 102. Furthermore, since the cable 104 is used as the first connecting portion, the load transmitted from the buckle 18 can be efficiently transmitted to the spool 123, thereby enabling the energy absorption mechanism 102 to operate with high precision. Furthermore, the central U-shaped portion 104A of the cable 104 is connected to the buckle 18 side, and both sides of the U-shaped portion 104A of the cable 104 are wound around the spool 123. In other words, two winding portions 104B and 104C are formed on the spool 123 at both ends 104D and 104E of the cable 104. Therefore, the load transmitted from the buckle 18 can be transmitted to the spool 123 more efficiently via the two winding portions 104B and 104C.

[0106] In the EA device 1A according to the second embodiment, the energy absorption mechanism 102 has an axial shaft 122 that is inserted coaxially with the spool 123 and is connected to be rotatable integrally with the spool 123. The torsion bar 121 is inserted coaxially with the axial shaft 122 and is connected to the axial shaft 122.

[0107] With this configuration, the torsion bar 121 can be connected to the spool 123 via the axial shaft 122. Furthermore, by interposing the axial shaft 122 between the torsion bar 121 and the spool 123, the outer diameter of the spool 123 can be increased when using a torsion bar 121 of the same size. This also increases the bending radius (i.e., the axial curvature of the cable 104) of the cable 104 wound around the spool 123. Here, strands are primarily used as cables. A strand is defined as a long member formed by twisting thin wires, such as wires. When the bending radius of a strand falls below a predetermined value, the twisted thin wires tend to unravel, potentially reducing the load-bearing capacity. To address this issue, the second embodiment allows the outer diameter of the spool 123 to be increased, thereby increasing the bending radius of the cable 104. The larger the bending radius of the cable 104, the more stable the load-bearing capacity of the cable 104 becomes.

[0108] In the second embodiment, the shaft 122 is preferably made of a metal with high hardness, such as iron, whereas the spool 123 is preferably made of a material, such as zinc die-cast, that is lower in hardness than the material of the shaft 122. This configuration can prevent the cable 104 wound around the spool 123 from wearing out due to the contact portion with the spool 123.

[0109] Third Embodiment A third embodiment will be described with reference to FIGS.

[0110] Fig. 15 is a perspective view of a buckle 18 to which the EA device 1B according to the third embodiment is applied. Fig. 16 is an exploded perspective view of the EA device 1B shown in Fig. 15.

[0111] 15 and 16, the basic configuration of the EA device 1B according to the third embodiment is the same as that of the EA device 1A according to the second embodiment. The major difference from the second embodiment is that the arrangement of the U-shaped portion 105A of the wire 105 and both end portions 105B and 105C is reversed.

[0112] In the third embodiment, the cable 104 and the wire 105 are connected to the buckle 18 by a connecting member 191. The connecting member 191 has a first member 191A disposed on the positive Z direction side and a second member 191B disposed on the negative Z direction side. The first member 191A is connected and fixed to the buckle 18. The second member 191B connects the cable 104 and the wire 105.

[0113] 16, both ends 105B and 105C of the wire 105 are connected and fixed to the second member 191B of the connecting member 191. The both ends 105B and 105C of the wire 105 are fixed to the second member 191B by any method such as crimping, as in the first embodiment.

[0114] On the other hand, the U-shaped portion 105A of the wire 105 is disposed at the end opposite to the ends 105B and 105C in the extending direction of the wire 105 (the positions of the ends 105B and 105C in the second embodiment).

[0115] Further, a connecting hole 191C penetrating in the Y direction is provided in the second member 191B of the connecting member 191. An engagement shaft 193 is attached to the connecting hole 191C. The engagement shaft 193 has a pair of disks 193B, 193C arranged opposite each other in the Y direction, each having a diameter larger than the diameter of the connecting hole 191C. The pair of disks 193B, 193C are connected by a shaft having a diameter smaller than the diameter of the connecting hole 191C. The shaft is inserted through the connecting hole 191C, with one disk 193B arranged on the negative Y direction side relative to the second member 191B and the other disk 193C arranged on the positive Y direction side relative to the second member 191B. The U-shaped portion 104A of the cable 104 is wound around the outer circumferential surface 193A of the shaft, thereby connecting the cable 104 to the connecting member 191.

[0116] The EA device 1B of the third embodiment also includes a wire case 192. The wire case 192 is disposed on the Y negative side of the base 108 and houses the portion of the wire 105 on the X positive side of the portion wound around the fastening bolt 131, i.e., the portion on the U-shaped portion 105A side. The wire case 192 also has the same function as the bracket 132 of the second embodiment, and is provided with a circular hole to which the pulley 133 is connected and through which the tip of the fastening bolt 131 is inserted on the Y negative side.

[0117] In the EA device 1B of the third embodiment, similarly to the second embodiment, when an excessive load is applied to the webbing 11 in an emergency such as a vehicle collision, the load is transmitted to the torsion bar 121 via the buckle 18, the connecting member 191, the cable 104, the spool 123, and the shaft 122. When a load exceeding a predetermined energy absorption load is transmitted, the torsion bar 121 is torsionally deformed about the axis L. As a result, the shaft 122 and the spool 123, whose rotation has been restricted by the torsion bar 121, rotate about the axis L, and the cable 104 is pulled out from the winding portions 104B and 104C toward the buckle 18. As a result, the buckle 18 moves in the direction of transmission of the load, as shown by arrow I in FIG.

[0118] At this time, the ends 105B and 105C of the wire 105 fixed to the connecting member 191 are also pulled out in the load transmission direction together with the U-shaped portion 104A of the cable 104 wound around the engagement shaft 193. Accordingly, with this pulling-out operation, the portion of the wire 105 on the side of the U-shaped portion 105A also moves toward the main body (the negative X direction) of the EA mechanism 102 and the final strength retaining unit 103, as shown by arrow J in FIG. 15 . Finally, as in the first embodiment, the U-shaped portion 105A of the wire 105 is locked by the fastening bolt 131. This prevents the wire 105 from being pulled out further in the load transmission direction, and the load is received by the fastening bolt 131 and other fixed portions to the vehicle body. As a result, the final strength retaining unit 103 of the EA device 1B can retain its final strength.

[0119] As described above, the EA device 1B according to the third embodiment, like the other embodiments, also includes an energy absorption mechanism (EA mechanism) 102 that limits the load applied to the webbing 11 that restrains the occupant and absorbs and alleviates the energy of the occupant, a final strength retention unit 103 that retains the final strength after activation of the EA mechanism 102, a cable 104 that connects the EA mechanism 102 to the buckle 18 that is the source of the load transmission, and a wire 105 that connects the final strength retention unit 103 to the buckle 18. This allows the same effects as the other embodiments to be achieved, and therefore, like the other embodiments, the final strength can be maintained while suppressing an increase in the size and weight of the entire device.

[0120] 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.

[0121] In the above embodiment, a configuration in which the cable 4 is used as the first connecting part has been exemplified. However, an element other than the cable 4 may be used as long as it is an element that can connect the buckle 18 and the EA mechanism 2. For example, a long belt-shaped member may be used as the first connecting part. In this case, in the EA mechanism 2 of the first embodiment, the belt-shaped member is wound around the outer peripheral surface 21A of the spool 21, and in the EA mechanism 102 of the second and third embodiments, the belt-shaped member is wound around the outer peripheral surface 123A of the spool 123. Examples of the belt-shaped member include a film material that is thinner than the webbing 11, a material similar to the webbing 11, etc.

[0122] Furthermore, in the above embodiment, a configuration in which the U-shaped wire 5 is used as the second connecting portion has been exemplified, but an element other than the U-shaped wire 5 may be used as long as it can connect the final strength retaining portion 3 to the buckle 18 and retain the final strength. For example, one or more linear members having one end connected to the buckle 18 may be used as the second connecting portion. Examples of linear members include elements similar to the cable 4 and wire 5 exemplified in the above embodiment. However, in the above embodiment, the wire 5 as an example of a linear member is bent into a U-shape and both ends 5B, 5C are connected to the buckle 18. In this case, only one end of the linear member is connected to the buckle 18, and the other end is not connected to the buckle 18 and is disposed in a direction away from the buckle 18 along the extension direction of the linear member.

[0123] When a linear member is used as the second connecting part in this manner, the final strength retaining part 3 has a hole disposed between one end and the other end of the linear member through which the linear member is inserted, and a wire end connected to the other end of the linear member and formed with a diameter larger than that of the hole so as not to pass through the hole. When the EA mechanism 2 is activated, the linear member is pulled out together with the first connecting part (cable 4) toward the buckle 18, and the final strength retaining part 3 can retain the final strength by having the wire end engaged in the hole.

[0124] The first connecting portion may be a linear member, such as a wire, similar to the cable 4 of the above embodiment. Similarly, the second connecting portion may be a U-shaped portion, such as the wire 5 of the above embodiment, with both ends connected to the buckle 18, and may be a linear member, such as a cable, similar to the wire 5.

[0125] In the above embodiment, the configuration in which the energy absorbing device 1 is applied to the buckle 18 has been exemplified, but it is sufficient that the energy absorbing device 1 is applied to at least one of the "components that guide or restrain the webbing 11" in the seat belt apparatus 10, such as the guide anchor 14 or the belt anchor 16. In other words, the energy absorbing device 1 can also be expressed as being part of the component that guides or restrains the webbing 11 in the seat belt apparatus 10, such as the belt anchor 16, the guide anchor 14, or the buckle 18.

[0126] For example, when it is desired to absorb energy from both the lap belt portion and the shoulder belt portion of the webbing 11, the energy absorption device 1 may be disposed only in the buckle 18, or the energy absorption device 1 may be disposed in all of the buckle 18, the belt anchor 16, and the guide anchor 14. On the other hand, when it is desired to absorb energy from only the lap belt portion of the webbing 11, the energy absorption device 1 may be disposed only in the belt anchor 16, or when it is desired to absorb energy from only the shoulder belt portion of the webbing 11, the energy absorption device 1 may be disposed only in the guide anchor 14.

[0127] The EA device 1 according to the first embodiment may also adopt the configuration of the cable 104 that is applied to the EA device 1A according to the second embodiment. That is, in the first embodiment, a U-shaped portion formed by bending the central portion of the cable 4 may be connected to the buckle 18 via a connecting part such as a ferrule 9 (or directly), so that the load applied to the webbing 11 that restrains the occupant can be transmitted to the cable 4 via this U-shaped portion, and further, portions of the cable 4 on both sides of the central U-shaped portion may be wound around spools 21, and both ends of the cable 4 may be fixed to the spools 21.

[0128] This international application claims priority based on Japanese Patent Application No. 2023-208930, filed on December 12, 2023, the entire contents of which are incorporated herein by reference.

[0129] DESCRIPTION OF SYMBOLS 1, 1A, 1B Energy absorption device (EA device) 2, 102 Energy absorption mechanism (EA mechanism) 21, 123 Spool 22, 121 Torsion bar 3, 103 Ultimate strength retaining portion 31, 131 Fastening bolt (fixing portion) 4, 104 Cable (first connecting portion) 5, 105 Wire (second connecting portion) 5A Curved portion 5B, 5C Both ends of wire 105A U-shaped portion 105B, 105C Ends 105D, 105E Wire end 10 Seat belt device 11 Webbing 14 Guide anchor (component that guides or restrains webbing) 16 Belt anchor (component that guides or restrains webbing) 18 Buckle (component that guides or restrains webbing) 132 Bracket (fixing portion) 132D, 132E Insertion hole

Claims

1. An energy absorption device comprising: an energy absorption mechanism that limits the load applied to a webbing that restrains an occupant and absorbs and alleviates the energy of the occupant; a final strength retention part that maintains final strength after operation of the energy absorption mechanism; a first connecting part that connects the energy absorption mechanism to a part that guides or restrains the webbing, which is the source of the load; and a second connecting part that connects the final strength retention part to the part.

2. The energy absorption device as described in claim 1, wherein the second connecting portion is a wire formed in a U-shape, the wire is connected to the part by a U-shaped portion formed by curving a central portion so that the load can be transmitted to the wire via the U-shaped portion, the final strength retention portion has a fixing portion which is provided with a pair of insertion holes through which the wire can be inserted, a portion of the wire on one end side of the U-shaped portion is inserted into one of the pair of insertion holes, and a portion of the wire on the other end side of the U-shaped portion is inserted into the other of the pair of insertion holes, wire ends having a diameter larger than that of the insertion holes are attached to both ends of the wire, the wire is pulled out toward the part together with the first connecting portion when the energy absorption mechanism is activated, and the final strength retention portion retains the final strength by the wire ends getting caught at the position of the insertion holes, whereby the one end and the other end of the wire opposite the part are engaged with the fixing portion.

3. The energy absorption device as described in claim 2, wherein the first connecting portion is a long cable, a U-shaped portion formed by bending a central portion of the cable is connected to the part so that the load can be transmitted to the cable via the U-shaped portion, and the energy absorption mechanism comprises: a spool around which both sides of the U-shaped portion of the cable are wound and both ends of the cable are fixed, and a torsion bar that is inserted coaxially with the spool, connected to the spool and also to the vehicle body, and is capable of twisting when a predetermined energy absorption load is applied.

4. The energy absorption device as described in claim 3, wherein the energy absorption mechanism has an axial shaft that is inserted coaxially with the spool and connected to be rotatable integrally with the spool, and the torsion bar is inserted coaxially with the axial shaft and connected to the axial shaft.

5. An energy absorption device as described in claim 1, wherein the second connecting portion is a wire formed in a U-shape, a pair of ends on either side of a U-shaped portion formed by curving a central portion of the wire are connected to the part so that the load can be transmitted to the wire via the pair of ends, the final strength retention portion has a fixing portion fixed to the vehicle body side, the fixing portion is inserted and installed inside the U-shape of the wire, the wire is pulled out toward the part together with the first connecting portion when the energy absorption mechanism is activated, and the final strength retention portion retains the final strength by engaging the U-shaped portion of the wire on the opposite side to the part with the fixing portion.

6. An energy absorption device as described in claim 5, wherein the first connecting portion is a long cable, a U-shaped portion formed by bending a central portion of the cable is connected to the part so that the load can be transmitted to the cable via the U-shaped portion, and the energy absorption mechanism comprises: a spool around which both sides of the U-shaped portion of the cable are wound and both ends of the cable are fixed, and a torsion bar that is inserted coaxially with the spool, connected to the spool and also connected to the vehicle body, and is capable of twisting deformation when a predetermined energy absorption load is applied.

7. The energy absorption device as described in claim 6, wherein the energy absorption mechanism has an axial shaft that is inserted coaxially with the spool and connected to be rotatable integrally with the spool, and the torsion bar is inserted coaxially with the axial shaft and connected to the axial shaft.

8. An energy absorption device as described in claim 1, wherein the second connecting portion is a wire formed into a U-shape with both ends connected to the part, the final strength retention portion has a fixing portion fixed to the vehicle body, the fixing portion is inserted into the inside of the U-shape of the wire and installed, the wire is pulled out toward the part together with the first connecting portion when the energy absorption mechanism is activated, and the final strength retention portion retains the final strength by engaging the U-shaped curved portion of the wire on the opposite side to the part with the fixing portion.

9. An energy absorption device as described in claim 1, wherein the first connecting part is a long cable, and the energy absorption mechanism comprises a spool around which the cable is wound, and a torsion bar that is inserted through the spool so as to be coaxial with the spool and connected to the spool, and that is capable of twisting deformation when a predetermined energy absorption load is applied.

10. An energy absorption device as described in claim 1, wherein the first connecting portion is a long belt-like member, and the energy absorption mechanism comprises a spool around which the belt-like member is wound, and a torsion bar that is inserted through the spool so as to be coaxial with the spool and connected to the spool, and that is capable of twisting deformation when a predetermined energy absorption load is applied.

11. The energy absorption device described in claim 1, wherein the second connecting portion is a linear member having one end connected to the part, the final strength retention portion has a hole arranged between the one end and the other end of the linear member and through which the linear member is inserted, and a wire end connected to the other end of the linear member and formed with a diameter larger than the hole so as not to pass through the hole, when the energy absorption mechanism is activated, the linear member is pulled out toward the part together with the first connecting portion, and the final strength retention portion retains the final strength by the wire end being engaged with the hole.

12. The energy absorbing device of claim 1, wherein the energy absorbing device is part of a belt anchor, a guide anchor, or a buckle.

13. A seat belt device comprising the energy absorbing device according to claim 1.

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