Energy absorption device and seat belt apparatus

Abstract

To provide an energy absorption device capable of stabilizing the energy absorption performance.SOLUTION: An energy absorption device 1 limits the load applied to a webbing 11 that restrains an occupant, absorbs and alleviates energy of the occupant. A piston 3 of the EA device 1 has a contact part 32 whose diameter continuously increases from an inner diameter Id1 of a pipe 4 as being apart from a buckle 18 along the extension direction from a position closer to the buckle 18 in the extension direction of the pipe 4, whose longitudinal cross-sectional shape is formed to be a curved surface shape that is convex to the outer side in the radial direction, and which is arranged so as to be in contact with the inner peripheral surface of the pipe 4. The pipe 4 of the EA device 1 has an enlarged-diameter part 43 which is formed in a diameter enlarged manner at one end 42 farther from the buckle 18 along the extension direction so as to have a concave curved surface shape with which the contact part 32 of the piston 3 can be in surface-contact. Before operation of the EA device 1, the contact part 32 of the piston 3 is placed in the enlarged-diameter part 43 of the pipe 4.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] In a conventional seat belt device equipped in a vehicle such as an automobile, for example, in an emergency such as when a large vehicle deceleration acts on the vehicle during a collision with the seat belt (webbing) worn, the locking means of the seat belt retractor operates to prevent the rotation of the spool in the webbing withdrawal direction, thereby restraining the occupant with the webbing and preventing the occupant from jumping out of the seat.

[0003] By the way, in this conventional seat belt device, when restraining the occupant with the webbing by the seat belt retractor in an emergency such as a vehicle collision, a vehicle deceleration occurs, so the occupant tries to move forward due to inertia. For this reason, a load is applied to the webbing, and the occupant is subjected to energy from this webbing. It is desirable that this energy be restricted as much as possible for the occupant.

[0004] Therefore, conventionally, a configuration has been proposed in which an energy absorption device (hereinafter also referred to as an EA device) that restricts the load applied to the webbing and absorbs and relaxes the energy applied to the occupant from the webbing is provided in the buckle in an emergency with the webbing worn (for example, Patent Document 1).

[0005] The conventional EA device for a buckle disclosed in Patent Document 1 includes a fixture fixed to a vehicle body, a tension transmission means having one end connected to a buckle and receiving a load applied to a webbing via the buckle, and a deformation member that directly contacts the fixture. The deformation member has a pipe member with one end connected to the fixture and a tapered pipe expansion member connected to the other end of the tension transmission member and moving inside the pipe member toward the fixture side by the tension transmitted from the tension transmission member. In this EA device for a buckle, when the tapered pipe expansion member of the deformation member moves inside the pipe member toward the fixture side due to the load received by the webbing, the tapered portion of the pipe expansion member moves while expanding the contact portion of the pipe member, thereby absorbing and mitigating the energy applied to the occupant from the webbing.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the conventional EA device for a buckle disclosed in Patent Document 1, since the shape of the pipe expansion member of the deformation member is a tapered shape, during EA operation, if the axis of the piston (i.e., the central axis of the pipe expansion member in the direction in which the pipe expansion member is pulled by the tension transmission member) is inclined with respect to the axis of the pipe to be expanded, the expansion rate of the pipe in the circumferential direction by the piston changes, and a situation where the generated load changes may occur. As a result, the limiting amount of the load applied to the webbing by the EA device changes, and there is a problem that the energy absorption performance by the EA device is difficult to stabilize.

[0008] An object of the present disclosure is to provide an energy absorption device and a seat belt device capable of stabilizing energy absorption performance.

Means for Solving the Problems

[0009] An energy absorption device according to one aspect of an embodiment of the present invention is an energy absorption device that restricts the load applied to a webbing that restrains an occupant and absorbs and mitigates the energy of the occupant, and includes a wire having one end connected to a component that guides or restrains the webbing, a piston connected to the other end of the wire, and a pipe that houses the piston. The piston is formed such that the diameter continuously increases from a position closer to the buckle in the extending direction of the pipe along the extending direction and away from the buckle, and the longitudinal cross-sectional shape is a curved surface shape convex outward in the radial direction. The piston has a contact portion that is arranged in contact with the inner peripheral surface of the pipe. The pipe has a diameter-expanded portion formed by expanding the diameter at one end along the extending direction away from the buckle so as to have a concave curved surface shape with which the contact portion of the piston can be in surface contact. Before the operation of the energy absorption device, the contact portion of the piston is installed in the diameter-expanded portion of the pipe.

Advantages of the Invention

[0010] According to the present disclosure, it is possible to provide an energy absorption device and a seat belt device capable of stabilizing energy absorption performance.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments will be described with reference to the accompanying drawings. For ease of understanding of the description, the same reference numerals are given to the same components in each drawing as much as possible, and redundant descriptions are omitted.

[0013] In the following description, the X direction, Y direction, and Z direction are perpendicular to each other. Typically, the X direction and Y direction are horizontal directions, and the Z direction is the vertical direction. The X direction is the axial direction of the pipe 4, and the direction in which the piston 3 moves in the pipe 4 during the operation of the EA device 1 is the positive X direction. Also, the X direction is the vehicle longitudinal direction when the EA device 1 is installed in the vehicle, with the negative X direction side being the vehicle front and the positive X direction side being the vehicle rear. The Y direction is the vehicle width direction when the EA device 1 is installed in the vehicle.

[0014] [First Embodiment] A first embodiment will be described with reference to FIGS. 1 to 12. FIG. 1 is a configuration diagram of a seat belt device 10 to which an EA device 1 according to the first embodiment is applied.

[0015] As shown in FIG. 1, the seat belt device 10 includes a webbing 11 (seat belt) for restraining an occupant, which is drawn out from a retractor 12. The retractor 12 is a device for winding up the webbing 11, and is fixedly provided at the lower part of the center pillar 13 on the vehicle interior side. In FIG. 1, the retractor 12 is illustrated by a solid line, but actually, the retractor 12 is installed inside the center pillar 13. The webbing 11 drawn out from the retractor 12 upward of the vehicle body is inserted through a guide anchor 14 attached to the upper part of the center pillar 13 and then folded back toward the lower part of the vehicle body. Then, the tip end portion of the webbing 11 is fixed to a belt anchor 16 provided between the center pillar 13 and the seat 15.

[0016] A tongue 17 is provided in a portion of the webbing 11 between the guide anchor 14 and the belt anchor 16 so as to penetrate the webbing 11. The tongue 17 is detachably attached to a buckle 18 disposed on the opposite side of the belt anchor 16 with the seat 15 interposed therebetween. That is, the buckle 18 detachably locks a tongue 17 slidably supported by the webbing 11 for restraining an occupant.

[0017] FIG. 2 is a front view of the buckle 18 to which the EA device 1 according to the first embodiment is applied. FIG. 3 is an exploded perspective view of the energy absorption (EA) device 1 in FIG. 2. FIG. 4 is a cross-sectional view taken along line A-A in FIG. 2, and is a longitudinal sectional view in the vicinity of the piston 3 in the EA device 1 before operation. FIG. 5 is a perspective view of the piston 3 in a state of being connected to the wire 2. In the present embodiment, in the seat belt device 10, a configuration in which the EA device 1 is applied to the buckle 18 will be illustrated and described.

[0018] As shown in FIGS. 1 and 2, the buckle 18 includes an energy absorption (EA) device 1. The EA device 1 operates in an emergency such as a vehicle collision in the vehicle seat belt device 10 to limit the load applied to the webbing 11 in the webbing wearing state and absorb and mitigate the energy applied from the webbing 11 to the occupant. The EA device 1 is fixed to the vehicle body and connected to the buckle 18 via the wire 2. The EA device 1 also functions as the base of the buckle 18. FIGS. 1 and 2 illustrate the state before the EA device 1 operates.

[0019] As shown in FIGS. 1, 2, or 3, the EA device 1 includes a wire 2, a piston 3, a pipe 4, an external bracket 5, an internal bracket 6, and an outer tube 7.

[0020] One end 21 of the wire 2 is connected to the buckle 18, and the other end 22 is connected to the piston 3. A ferrule 23 is connected to one end 21 of the wire 2. As shown in FIG. 2, the ferrule 23 is connected to the buckle 18. That is, the wire 2 is connected to the buckle 18 via the ferrule 23. Thereby, the load applied to the webbing 11 via the buckle 18 is transmitted to the wire 2.

[0021] The piston 3 is installed so as to be movable in the X direction, which is the extending direction of the pipe 4, by an external force received from the wire 2. As shown in FIGS. 3 and 4, the piston 3 is provided with a hole 31 penetrating along the X direction at the central position when viewed from the X direction, which is the moving direction. The other end 22 of the wire 2 penetrates through the hole 31 of the piston 3 and protrudes to the X negative direction side of the piston 3 (that is, the side away from the buckle 18 in the extending direction of the pipe 4 with respect to the piston 3), and a cable ferrule 24 is connected to this protruding portion. As shown in FIG. 4, the cable ferrule 24 is fixed to the other end 22 of the wire 2 and is formed with a larger radial dimension than the hole 31 of the piston 3. When the wire 2 is pulled toward the buckle 18 side, the cable ferrule 24 fixed to the wire 2 is also pulled integrally with the other end 22 of the wire 2 to the X positive direction side. For this reason, the piston 3 through which the wire 2 is inserted at a position on the X positive direction side of the cable ferrule 24 is pressed toward the X positive direction side by the cable ferrule 24 pulled toward the X positive direction side, and moves integrally with the wire 2 and the cable ferrule 24 to the X positive direction side. That is, the wire 2 is connected to the piston 3 via the cable ferrule 24. Thereby, a load applied to the webbing 11 is transmitted to the piston 3 via the wire 2.

[0022] The pipe 4 is a cylindrical member that houses the piston 3. As shown in FIGS. 2 and 3, the pipe 4 is installed so as to extend in the X direction. The pipe 4 is, for example, a cylinder having a circular cross section as shown in FIG. 3, and is installed such that the central axis is parallel to the X direction.

[0023] The external bracket 5 is a member that positions the wire 2 with the middle part of the wire 2 inserted therethrough. In the external bracket 5, holes 53 and 54 having the same center position and diameter are formed in a pair of side walls 51 and 52 that are oppositely arranged in the Y direction, respectively. An annular ring member 55 is inserted between the pair of side walls 51 and 52 so as to be concentric with the two holes 53 and 54. The dimension of the ring member 55 in the Y direction is approximately the same as the interval between the pair of side walls 51 and 52, and the diameter of the inner peripheral surface of the annular ring member 55 is the same as or larger than the two holes 53 and 54.

[0024] A cylindrical fixing member 56 is inserted through the two holes 53 and 54 and the ring member 55 from one side wall 52 on the positive Y direction side of the pair of side walls 51 and 52 of the external bracket 5 and penetrates to the other side wall 51 on the negative Y direction side for attachment. The central hole of the cylindrical fixing member 56 is a fixing hole 56a, and the EA device 1 is fixed to the vehicle body by inserting a bolt 71 (see FIG. 1) not shown into the fixing hole 56a. The pair of side walls 51 and 52 are integrally connected by a connecting wall 57 extending in the Z direction at the end on the positive X direction side.

[0025] The internal bracket 6 is a member that connects the external bracket 5 and the pipe 4. The internal bracket 6 is a columnar member with the axial direction being the X direction as shown in FIG. 3, and a through hole 61 penetrating along the axial direction is provided at the center position when viewed from the X direction. The wire 2 is inserted through the through hole 61 and is arranged so as to be movable relative to the internal bracket 6 toward the external bracket 5 side and the pipe 4 side.

[0026] In a portion from the end face 6a on the positive X-direction side to a predetermined position on the negative X-direction side of the inner bracket 6, a pair of recesses 62 are provided which are recessed from both sides in the Y direction toward the axis. On the other hand, on a pair of side walls 51, 52 of the outer bracket 5, connecting walls 58, 59 protruding in the negative X direction are respectively provided. The connecting walls 58, 59 are formed such that the width dimension in the Z direction is the same as or slightly smaller than the width dimension in the Z direction of the recesses 62. Thereby, as shown by the dotted arrow B in FIG. 3, when connecting the inner bracket 6 to the outer bracket 5 from the negative X-direction side, the connecting walls 58, 59 of the outer bracket 5 are inserted into the respective recesses 62 of the inner bracket 6 from the positive X-direction side and are disposed opposite to the bottom surfaces 62a of the pair of recesses 62.

[0027] Also, in a portion on the negative Z-direction side of the outer peripheral surface 6b of the inner bracket 6, a groove 63 is provided which is recessed in the positive Z direction. This groove 63 is disposed at a position in the X direction where the pair of recesses 62 are present, and is formed such that the depth in the positive Z direction reaches the position where the bottom surfaces 62a of the pair of recesses 62 are present. Also, at the central portion in the Y direction of the groove 63, that is, at the position overlapping with the hole 61 through which the wire 2 is inserted, the depth of the groove 63 is formed to a dimension that does not reach the hole 61 (see FIG. 6).

[0028] On the other hand, on the ends on the negative Z-direction side of the pair of connecting walls 58, 59 of the outer bracket 5, grooves 58a, 59a are also provided which are recessed in the positive Z direction. These grooves 58a, 59a are disposed such that in a state where the connecting walls 58, 59 are fitted into the recesses 62, the position in the X direction is the same as the groove 63 of the inner bracket 6. Also, the depth of the grooves 58a, 59a is formed to a dimension such that the positions in the positive Z direction are substantially the same as the portions on both sides in the Y direction excluding the above-mentioned central portion in the Y direction of the groove 63 of the inner bracket 6.

[0029] The connecting walls 58 and 59 are fitted into the recess 62, and the groove 63 of the internal bracket 6 is sandwiched between the grooves 58a and 59a of the connecting walls 58 and 59. In a state where the grooves 63, 58a, and 59a overlap at the same position in the X direction, a single connecting plate 64 is inserted into these grooves 63, 58a, and 59a from the Z negative direction side as shown by the dotted arrows C1 and C2 in Fig. 3. The connecting plate 64 is formed such that its thickness in the X direction is the same as or slightly smaller than the width dimensions of the grooves 63, 58a, and 59a. The outer peripheral surface 64a on the Z negative direction side of the connecting plate 64 is formed in an arc shape having the same diameter as the cylindrical shape of the internal bracket 6.

[0030] Among the portions on the Z positive direction side of the connecting plate 64, fitting portions 64b, 64c, and 64d that fit with the grooves 63, 58a, and 59a are respectively provided at the central portion in the Y direction. The positions of the tip ends on the Z positive direction side of the fitting portions 64b, 64c, and 64d are such that at least a part of the fitting portions 64b, 64c, and 64d abuts against at least a part of the bottom surfaces of the grooves 63, 58a, and 59a, and when further relative movement of the connecting plate 64 in the Z positive direction with respect to the internal bracket 6 is restricted, the arc shape of the outer peripheral surface 64a of the connecting plate 64 in the X direction view is formed so as to overlap with the circular shape of the cylindrical shape of the internal bracket 6. By using such a connecting plate 64, the internal bracket 6 can be reliably connected to the external bracket 5 without increasing the outer diameter of the internal bracket 6.

[0031] On the other hand, the internal bracket 6 is connected to the end portion 41 (the other end portion) on the X positive direction side of the pipe 4, for example, by screw fastening or the like at the opening 65 on the X negative direction side. The inner diameter of the opening 65 is formed to be substantially the same size as the outer diameter of the end portion 41 of the pipe 4. On the other hand, since the through hole 61 of the internal bracket 6 only needs to be able to insert at least the wire 2, the diameter of the through hole 61 is smaller than the inner diameter of the opening 65. For this reason, a stepped surface 66 that is formed in an annular shape along the circumferential direction of the internal bracket 6 in the X direction view is provided between the end portion on the X negative direction side of the through hole 61 and the opening 65. The stepped surface 66 is arranged facing the X negative direction side.

[0032] With the configuration of the above-described EA device 1, as shown by the dashed line in FIG. 3, the wire 2 is inserted between the inner surface 57a of the connecting wall 57 of the external bracket 5 and the outer peripheral surface 55a of the ring member 55 (see FIG. 6), and is inserted through the through hole 61 of the internal bracket 6, so that the bending angle of the wire 2 can be kept constant inside the EA device 1. Further, one end 21 of the wire 2 is connected to the buckle 18 via the ferrule 23, and the other end 22 of the wire 2 is connected to the piston 3 via the cable ferrule 24 as shown by the dashed line in FIG. 3. Thus, even if the wire 2 slides inside the EA device 1, the distance along the wire 2 between the buckle 18 and the piston 3 can be kept constant.

[0033] As shown in FIG. 1, the exterior tube 7 is a cylindrical member that houses the internal bracket 6, the pipe 4, and the piston 3 inside. As shown in FIG. 3, the exterior tube 7 is installed so as to extend in the X direction. The exterior tube 7 is, for example, a cylinder having a circular cross section as shown in FIG. 3, and is installed such that its central axis is parallel to the X direction. Further, as shown by the dotted arrow D in FIG. 3, for example, the exterior tube 7 is installed outside the internal bracket 6, the pipe 4, and the piston 3 from the X negative direction side, and the end 7a on the X positive direction side is connected to the external bracket 5 by an arbitrary method such as screw fastening or a locking structure.

[0034] By providing such an exterior tube 7, when the EA device 1 is installed on the vehicle body, even if an external force is applied to, for example, the X negative direction side of the pipe 4, that is, the free end side portion that is not connected to the external bracket 5 or the like in the longitudinal direction, the external force can be received by the exterior tube 7, so that deformation of the pipe 4, the internal bracket 6, etc. can be suppressed. Thereby, it is possible to suppress the addition of unnecessary resistance during the movement of the piston 3 due to the deformation of the pipe 4 or the like, and to suppress the occurrence of malfunctions during the operation of the EA device 1.

[0035] In the assembly drawing of the EA device 1 except for FIGS. 1 and 3, the illustration of the exterior tube 7 is omitted.

[0036] Particularly in this embodiment, as shown in FIGS. 3 to 5, the piston 3 has a contact portion 32 that is arranged in contact with the inner peripheral surface of the pipe 4. The contact portion 32 is located on the side closer to the buckle 18 (i.e., the positive X-direction side) in the extending direction of the pipe 4, and along the X direction, as it moves away from the buckle 18 (i.e., toward the negative X-direction side), the diameter continuously increases from the inner diameter Id1 of the pipe 4, and the longitudinal cross-sectional shape is formed into a curved surface shape that protrudes radially outward. Particularly in this embodiment, as an example of the curved surface shape of such a contact portion 32, a spherical shape is applied. When the contact portion 32 has a spherical shape, as shown in FIG. 4, the spherical surface is formed such that the center O of the spherical surface is arranged on the axis Q of the wire 2 indicated by the dashed line in FIG. 4.

[0037] On the other hand, as shown in FIGS. 2 to 4, the pipe 4 has a diameter-expanded portion 43 formed by expanding the diameter at one end 42 on the side away from the buckle 18 (i.e., the negative X-direction side) along the extending direction, so that the contact portion 32 of the piston 3 can be in surface contact with a concave curved surface shape. The "concave curved surface shape" of the diameter-expanded portion 43 according to this embodiment means, as shown in FIG. 4, a shape that curves radially outward of the pipe 4 along the advancing direction of the piston 3 in the longitudinal cross-section (i.e., the cross-section along the XY plane) of the pipe 4.

[0038] When the contact portion 32 of the piston 3 has a spherical shape, for example, as shown in FIG. 4, the curved surface shape of the inner peripheral surface of the diameter-expanded portion 43 of the pipe 4 also has a spherical shape with the same radius R as the contact portion 32. The inner diameter of the diameter-expanded portion 43 continuously increases from the position on the side closer to the buckle 18 (i.e., the positive X-direction side) in the extending direction of the pipe 4, along the X direction, as it moves away from the buckle 18 (i.e., toward the negative X-direction side), from the inner diameter Id1 of the pipe 4 to a maximum diameter Id2. As shown in FIG. 4, the maximum diameter Id2 of the inner diameter of this diameter-expanded portion 43 is the same as the spherical diameter (2×R) of the contact portion 32 of the piston 3.

[0039] As shown in FIGS. 2 and 4, before the EA device 1 operates, the contact portion 32 of the piston 3 is installed in the enlarged diameter portion 43 of the pipe 4. That is, a part of the convex spherical surface of the contact portion 32 of the piston 3 is in surface contact with the concave spherical surface of the enlarged diameter portion 43 of the pipe 4. Thereby, the piston 3 is positioned at the position of one end portion 42 on the X negative direction side of the pipe 4. As described above, since the enlarged diameter portion 43 is formed by enlarging the inner diameter Id1 of the pipe 4, the outer shape of the contact portion 32 of the piston 3 formed in a spherical shape having the same diameter as the enlarged diameter portion 43 (that is, the diameter 2×R of the spherical shape of the contact portion 32) is also formed larger than the inner diameter Id1 of the pipe 4. Thereby, unless a tensile force equal to or greater than a predetermined value is applied to the wire 2 and transmitted to the piston 3, the piston 3 is restricted from moving to the X positive direction side from the X direction position of the enlarged diameter portion 43 of the pipe 4.

[0040] The operation of the EA device 1 will be described with reference to FIG. 6. FIG. 6 is a longitudinal sectional view showing the state after the EA device 1 operates.

[0041] When a tensile load equal to or greater than a predetermined value acts on the buckle 18 and the wire 2 is pulled in the drawing direction E (the Z positive direction side indicated by the arrow E in the example of FIG. 6), a load is also transmitted to the cable ferrule 24 fixed to the end portion 22 of the wire 2 in the X positive direction side. Thereby, the piston 3 through which the wire 2 is inserted at a position on the X positive direction side from the cable ferrule 24 is pressed in the X positive direction side by the cable ferrule 24. As shown by the arrow F, the piston 3 moves in the pipe 4 from the enlarged diameter portion 43 to the X positive direction side.

[0042] Here, as described above, the portion of the pipe 4 on the positive X-direction side from the enlarged diameter portion 43 has an inner diameter Id1 that is smaller than the inner diameter Id2 of the contact portion 32 and the enlarged diameter portion 43 before the operation of the EA device 1 (in FIG. 6, the original inner diameter Id1 is shown by a dotted line). When a tensile load equal to or greater than a predetermined value is applied to the wire 2 in the positive X-direction, the contact portion 32 of the piston 3 expands the inner peripheral surface of the pipe 4 radially outward as indicated by the arrow G, and the inner diameter Id1 of the pipe 4 can be expanded to the same inner diameter Id2 as the contact portion 32 and the enlarged diameter portion 43. As a result, the piston 3 can move in the positive X-direction within the pipe 4 while gradually expanding the pipe 4 from the end side in the negative X-direction.

[0043] As described above, when a tensile load equal to or greater than a predetermined value acts on the buckle 18, the EA device 1 of the buckle 18 according to the present embodiment allows the piston 3 to move within the pipe 4 toward the external bracket 6 side, thereby allowing the buckle 18 to move in the tensile direction E. When the EA device 1 operates, the webbing 11 is loosened.

[0044] Also, as shown in FIG. 6, when the contact portion 32 of the piston 3 reaches the end portion 41 on the positive X-direction side of the pipe 4, the contact portion 32 abuts against the stepped surface 66 of the internal bracket 6 that is exposed inside the pipe 4. As a result, further movement of the piston 3 in the positive X-direction is restricted, and movement of the buckle 18 in the tensile direction E is also restricted. Consequently, the operation of loosening the webbing 11 associated with the operation of the EA device 1 also stops.

[0045] In the present embodiment, the external bracket 5 corresponds to "a bracket disposed between the buckle 18 and the pipe 4 that guides the wire 2 inside and guides it to the pipe 4", and the internal bracket 6 corresponds to "the connecting portion between the pipe 4 and the bracket (external bracket 5) against which the contact portion 32 of the piston 3 abuts after the operation of the EA device 1".

[0046] Thus, after the operation of the EA device 1, the contact portion 32 of the piston 3 moves to the other end portion 41 of the pipe 4 closer to the buckle 18 in the extending direction of the pipe 4, and the inner diameter of the portion of the pipe 4 excluding the other end portion 41 is expanded from the initial inner diameter Id1 to the maximum diameter Id2 of the expanded diameter portion 43 as the piston 3 moves. A curved surface having the same shape as the contact portion 32 of the piston 3 is formed at the other end portion 41 of the pipe 4. That is, a concave curved surface having a spherical shape similar to the contact portion 32 is formed on the inner peripheral surface side of the pipe 4, and a convex curved surface having a spherical shape that is larger than the spherical shape of the contact portion 32 by the thickness of the pipe 4 and is concentric with the spherical shape of the contact portion 32 is formed on the outer peripheral surface side of the pipe 4.

[0047] Next, the effects of the first embodiment will be described with reference to FIGS. 7 and 8.

[0048] FIG. 7 is a schematic diagram for explaining the operation of the piston 103 according to the comparative example. FIG. 7(A) shows a state where the piston 103 is fitted into the expanded diameter portion 143, and FIG. 7(B) shows an example of a state where the pipe 4 is expanded with the piston 103 tilted.

[0049] As shown in FIG. 7, the piston 103 of the comparative example is formed in a frustum of a cone shape. The diameter of the upper surface of the frustum of a cone shape is the same dimension as the inner diameter Id1 of the pipe 4, and the diameter of the bottom surface is the same dimension as the maximum diameter Id2 of the inner diameter of the expanded diameter portion 143 of the pipe 4. The piston 103 is installed in the expanded diameter portion 143 such that one end surface corresponding to the upper surface of the frustum of a cone shape is arranged on the X positive direction side, and the other end surface corresponding to the bottom surface is arranged on the X negative direction side. Therefore, the outer peripheral surface corresponding to the side surface of the frustum of a cone shape becomes the contact portion 132. As shown in FIG. 7(A), the contact portion 132 has a tapered shape that is inclined with respect to the axis Q (X direction) of the wire 2 and the pipe 4. Also, the shape of the inner peripheral surface of the expanded diameter portion 143 of the pipe 4 is also a tapered shape that can be in surface contact with the contact portion 132, and the inclination angle is the same as that of the contact portion 132.

[0050] As shown in FIG. 7(A), even in the piston 103 of the comparative example, if it is arranged coaxially with the pipe 4 and the contact portion 132 is in surface contact with the enlarged diameter portion 143 and is in a fitting state, when a tensile force acts on the wire 2, the contact portion 132 of the piston 103 can move in the +X direction while expanding the pipe 4, similar to the present embodiment.

[0051] On the other hand, as shown in FIG. 7(B), consider the case where the piston 103 tilts while moving inside the pipe 4. At this time, the axis of the piston 103 (that is, the central axis of the piston 103 in the direction in which the piston 103 is pulled by the wire 2) tilts with respect to the central axis Q of the pipe 4 (that is, the axis along the X direction), and it no longer aligns coaxially with the central axis Q of the pipe 4.

[0052] If the contact portion 132 of the piston 103 moves in the +X direction while expanding the pipe 4 in this tilted state of the piston 103, the maximum diameter Od of the piston 103 in the direction orthogonal to the extending direction of the pipe 4 (Y direction) becomes smaller than the maximum diameter Id2 of the enlarged diameter portion 143 shown in FIG. 7(A). Further, as shown in FIG. 7(B), the arrangement of the maximum diameter Od is shifted in the Y direction (the +Y direction side in the example of FIG. 7(B)) with respect to the central axis Q of the pipe 4. When a tensile force acts on the wire 2 in this state, the rate of pipe expansion in the circumferential direction of the pipe 4 by the piston 103 changes, and a situation where the generated load changes can occur. For example, in the case of the example in FIG. 7(B), since the piston 103 is tilted toward the +Y direction side, the +Y direction side in the circumferential direction of the circular cross-sectional shape of the pipe 4 is expanded more, and a larger load than before is required for the expansion on the +Y direction side. As a result, the limit value of the load applied to the webbing 11 by the EA device 1 changes, so the energy absorption performance by the EA device 1 becomes difficult to stabilize.

[0053] In addition, since the balance of the generated loads in the circumferential direction of the cross-sectional circular shape of the pipe 4 is disrupted, the pipe 4 cannot smoothly expand in the radial direction, and for example, unexpected deformations of the pipe 4 may occur, such as a part of the pipe 4 being recessed inward in the radial direction or the central axis of the pipe 4 bending from the X direction. In this case, if the movement of the piston 103 within the pipe 4 is inhibited, the energy absorption performance by the EA device 1 may not be exhibited.

[0054] These problems can be solved by making the contact portion 32 of the piston 3 spherical as in the present embodiment. FIG. 8 is a schematic diagram for explaining the operation of the piston 3 according to the first embodiment. FIG. 8 illustrates a state in which the piston 3 of the first embodiment is inclined and installed in the diameter-expanded portion 43 of the pipe 4, similar to FIG. 7(B).

[0055] As shown in FIG. 8, in the piston 3 of the first embodiment, since the contact portion 32 has a spherical shape, even when the piston 3 is inclined and installed in the diameter-expanded portion 43, the center O of the spherical shape is maintained in a state of being disposed on the central axis Q of the pipe 4. For this reason, the state in which the contact portion 32 is in surface contact with and fitted to the diameter-expanded portion 43 can also be maintained, and the maximum diameter of the piston 3 in the direction (Y direction) orthogonal to the extending direction of the pipe 4 is also maintained to be the same as the maximum diameter Id2 of the diameter-expanded portion 143. Further, the arrangement of the maximum diameter of the piston 3 is also maintained in a state that is uniform in the Y direction with respect to the central axis Q of the pipe 4.

[0056] Therefore, even if a tensile force acts on the wire 2 in this state, there is no change in the circumferential pipe expansion rate of the pipe 4 by the piston 3, and the generated load also does not change, so the energy absorption performance by the EA device 1 can be maintained in a stable state.

[0057] Furthermore, since there is no bias in the generated load in the circumferential direction, the advancing direction of the piston 3 easily returns to the axial direction of the pipe 4. In the example of FIG. 8, although the piston 3 is inclined toward the positive Y direction side, when a tensile force is received from the positive X direction side via the wire 2, as shown by the arrow H, the contact portion 32 rotates in the clockwise direction around the center O and around the Z axis along the diameter-expanded portion 43, and acts so that the wire 2 inserted through the piston 3 faces the X direction.

[0058] According to the buckle 18 according to the first embodiment as described above, by making the shape of the piston 3 of the EA device 1 and the shape of the enlarged diameter portion 43 of the pipe 4 into spherical shapes that can be in surface contact with each other, the energy absorption performance by the energy absorption device 1 can be stabilized.

[0059] Note that the "spherical shape" of the contact portion 32 of the piston 3 and the enlarged diameter portion 43 of the pipe 4 is not limited to those in which the radius R from the center O is the same over the entire surface in contact with each other. For example, a convex spherical surface of the contact surface, or a depression, groove, hole, flat surface, etc. may be provided in a part of the concave spherical surface of the enlarged diameter portion 43. The main point is that as long as the contact portion 32 of the piston 3 and the enlarged diameter portion 43 of the pipe 4 can be in surface contact and do not inhibit relative movement, elements other than a spherical surface may be provided on the surface.

[0060] Note that the shapes of the contact portion 32 of the piston 3 of the EA device 1 and the enlarged diameter portion 43 of the pipe 4 may be other than spherical shapes. The shape of the contact portion 32 should be such that at least from the position on the side closer to the buckle 18 (that is, the positive X direction side) in the extending direction of the pipe 4, along the X direction, as it moves away from the buckle 18 (that is, as it becomes the negative X direction side), the diameter continuously increases from the inner diameter Id1 of the pipe 4, and the longitudinal cross-sectional shape is formed into a curved surface shape convex to the outside in the radial direction. The shape of the enlarged diameter portion 43 may be formed by enlarging the diameter so as to be a concave curved surface shape with which the contact portion 32 of the piston 3 can be in surface contact.

[0061] By making the shapes of the contact portion 32 of the piston 3 and the enlarged diameter portion 43 of the pipe 4 into curved surface shapes that can be in surface contact with each other in this way, similar to the case of a spherical shape, when a tensile force acts on the wire 2, the change in the pipe expansion rate in the circumferential direction of the pipe 4 by the piston 3 can be suppressed, and the change in the generated load can also be suppressed. Therefore, the energy absorption performance by the EA device 1 can be maintained in a stable state.

[0062] In the EA device 1 according to the first embodiment, the piston 3 has a hole 31 that penetrates the other end 22 of the wire 2. The EA device 1 also has a cable ferrule 24 that penetrates the hole 31 and is fixed to the other end 22 of the wire 2 that protrudes from the buckle 18 in the extending direction of the pipe 4 with respect to the piston 3 on the side away from the buckle 18 (X negative direction).

[0063] With this configuration, the cable ferrule 24 can connect the piston 3 to the end 22 of the wire 2 without interposing other elements between the piston 3 and the inner bracket 6 in the internal space of the pipe 4. As a result, when the EA device 1 operates, the piston 3 can be smoothly moved in the positive X direction side in the pipe 4 until it hits the inner bracket 6, and it is easy for the contact portion 32 of the piston 3 to reach the end 41 on the positive X direction side of the pipe 4. As a result, it is easy to maximize the distance by which the contact portion 32 of the piston 3 expands the diameter of the pipe 4, and it is also easy to maximize the energy absorption effect by the EA device 1.

[0064] Also, the cable ferrule 24 may be formed as an integral part with the piston 3. Thereby, the number of parts of the EA device 1 can be reduced.

[0065] [Modification Example] A modification example of the first embodiment will be described with reference to FIGS. 9 to 12. FIG. 9 is a front view of the buckle 18 to which the EA device 1A according to the modification example of the first embodiment is applied. The schematic configuration of FIG. 9 is the same as that of FIG. 2. In FIG. 9, the state before the EA device 1A according to the modification example operates is illustrated. FIG. 10 is a cross-sectional view taken along line I-I in FIG. 9 and is a longitudinal cross-sectional view of the vicinity of the piston 3A in the EA device 1A before operation. FIG. 11 is a perspective view of the piston 3A according to the modification example in a state of being connected to the wire 2. FIGS. 9, 10, and 11 respectively correspond to FIGS. 2, 4, and 5.

[0066] As shown in FIGS. 9 to 11, in the EA device 1A according to the modification example, the shape of the piston 3A is different from that of the piston 3 in the first embodiment.

[0067] The piston 3A according to the modified example further has a cable ferrule portion 33 in addition to the hole 31 and the contact portion 32. The cable ferrule portion 33 is integrally formed with the contact portion 32 of the piston 3 on the side closer to the buckle 18 (the positive X direction side) in the extending direction of the pipe 4 with respect to the contact portion 32.

[0068] In the piston 3A, the hole 31 is provided so as to penetrate through the cable ferrule portion 33 and the contact portion 32. The other end portion 22 of the wire 2 is inserted into the hole 31 of the piston 3A. When the other end portion 22 of the wire 2 is inserted into the hole 31 from the positive X direction side, it first passes through the portion of the cable ferrule portion 33 and then reaches the portion of the contact portion 32. In this state, the cable ferrule portion 33 is fixed to the wire 2 through which the other end portion 22 passes through the hole 31. Thereby, the piston 3A is connected to the other end portion 22 of the wire 2, and the load applied to the webbing 11 is transmitted to the piston 3A via the wire 2.

[0069] FIG. 12 is a longitudinal sectional view showing the state after the EA device 1A according to the modified example has operated. FIG. 12 corresponds to FIG. 6.

[0070] When a tensile load equal to or greater than a predetermined value acts on the buckle 18 and the wire 2 is pulled in the drawing direction (the positive Z direction side indicated by the arrow J in the example of FIG. 12), a load is also transmitted to the piston 3A fixed to the end portion 22 of the wire 2 by the cable ferrule portion 33 in the positive X direction. Thereby, as shown by the arrow K, the piston 3A moves in the positive X direction side from the diameter-expanded portion 43 in the pipe 4. When a tensile load equal to or greater than a predetermined value is applied to the wire 2 in the positive X direction, the contact portion 32 of the piston 3A presses the inner peripheral surface of the pipe 4 radially outward as shown by the arrow L, and the inner diameter Id1 of the pipe 4 can be expanded to the same inner diameter Id2 as the contact portion 32 and the diameter-expanded portion 43. Thereby, the piston 3A can move in the positive X direction in the pipe 4 while gradually expanding the pipe 4 from the end portion side in the negative X direction to the positive X direction.

[0071] Note that, as shown in FIGS. 10 to 12, the cable ferrule portion 33 is formed such that its dimension in the radial direction is smaller than that of the contact portion 32, similar to the cable ferrule 24 of the first embodiment. Therefore, even if the cable ferrule portion 33 is disposed on the front side in the moving direction of the piston 3A with respect to the contact portion 32, when the piston 3A moves in the pipe 4, it does not inhibit the diameter expansion operation of the pipe 4 by the contact portion 32 or the movement of the piston 3A.

[0072] Further, as shown in FIG. 12, when the contact portion 32 of the piston 3A reaches the end portion 41 on the positive X direction side of the pipe 4, the cable ferrule portion 33 abuts against the stepped surface 66 of the internal bracket 6 that is exposed inside the pipe 4. As a result, further movement of the piston 3A in the positive X direction is restricted, and movement of the buckle 18 in the tensile direction J is also restricted. As a result, the operation of loosening the webbing 11 accompanying the operation of the EA device 1A is also stopped.

[0073] Note that, in the piston 3A according to the modification, since the cable ferrule portion 33 is disposed on the positive X direction side with respect to the contact portion 32, it is preferable to increase the depth of the opening 65 of the internal bracket 6 in the X direction compared to the first embodiment and move the position of the stepped surface 66 to the positive X direction side compared to the first embodiment. Thereby, the reaching position of the contact portion 32 of the piston 3A in the pipe 4 can be made the same as that of the piston 3 in the first embodiment.

[0074] [Second Embodiment] The second embodiment will be described with reference to FIGS. 13 to 17. FIG. 13 is a perspective view of an EA device 1B according to the second embodiment. FIG. 14 is a longitudinal sectional view of the EA device 1B shown in FIG. 13. FIGS. 13 and 14 illustrate a state before the EA device 1B operates.

[0075] As shown in FIGS. 13 and 14, the EA device 1B according to the second embodiment includes a fixing portion 8. The fixing portion 8 is a component for fixing the EA device 1B to the vehicle body. The fixing portion 8 is formed by integrating the external bracket 5 and the pipe 4 of the first embodiment as an integral part. The fixing portion 8 can be manufactured, for example, from a single iron plate using a well-known method. By integrally manufacturing the external bracket 5 and the pipe 4 as the fixing portion 8, the number of parts of the EA device 1B can be reduced.

[0076] In the external bracket 5 of the fixing portion 8, a cylindrical fixing member 56 is attached through a pair of side walls 51 and 52 in the same manner as in the first embodiment. The central hole of the cylindrical fixing member 56 is the fixing hole 56a. By inserting a bolt 71 (see FIGS. 14 and 16) through the fixing hole 56a, the fixing portion 8 is fixed to the vehicle body, and thereby the EA device 1 is fixed to the vehicle body.

[0077] In the EA device 1B according to the second embodiment, a connecting portion between the external bracket 5 and the pipe 4 corresponding to the internal bracket 6 of the first embodiment is not provided. In the first embodiment, the internal bracket 6 as the connecting portion functioned as an element that restricted the movement of the piston 3 when the contact portion 32 of the piston 3 hit after the operation of the EA device 1. However, in the second embodiment, there is no such element having this function. Therefore, in the second embodiment, a pair of guide portions 81 and 82 provided inside the external bracket 5 of the fixing portion 8 for guiding the wire 2 are substituted as elements for restricting the movement of the piston 3B. The pair of guide portions 81 and 82 are arranged to face each other with the wire 2 sandwiched therebetween at the same position along the moving direction (X direction) of the piston 3B.

[0078] In the EA device 1B of the second embodiment, as shown in FIG. 14, the contact portion 32 of the piston 3B is formed as a convex spherical surface, and the enlarged diameter portion 43 of the pipe 4 is formed as a concave spherical surface that can be in surface contact with the contact portion 32, which is common to the EA device 1 of the first embodiment. On the other hand, the piston 3B is different from the EA device 1 of the first embodiment in that it has an abutting portion 34. The abutting portion 34 is integrally formed with the contact portion 32 of the piston 3 on the side opposite to the cable ferrule 24, that is, on the side closer to the buckle 18 (the positive X direction side) in the extending direction of the pipe 4 with respect to the contact portion 32.

[0079] The dimension of the abutting portion 34 in the X direction is formed to be a length such that the tip portion can contact the pair of guide portions 81 and 82 when the contact portion 32 of the piston 3B reaches the end portion 41 on the positive X direction side of the pipe 4 after the operation of the EA device 1B. The abutting portion 34 is a columnar member formed concentrically with the hole 31 in the X-direction view, and the hole 31 is provided to penetrate through the axis. The outer diameter of the abutting portion 34 is formed smaller than the inner diameter of the pipe 4 so as not to hinder the movement of the piston 3B within the pipe 4.

[0080] In the EA device 1B of the second embodiment, in a state where the piston 3B has moved to the end portion 41 on the side closer to the buckle 18 (the positive X direction side) in the extending direction of the pipe 4 after the operation of the EA device 1B, the tip portion on the end portion 41 side of the piston 3B, that is, the tip of the abutting portion 34 abuts against the pair of guide portions 81 and 82. Thereby, the movement of the piston 3B is restricted.

[0081] In this embodiment, specifically, one of the pair of guide portions 81 and 82, the guide portion 81, can be applied to a bolt 71 that is inserted into a fixing hole 56a provided in the external bracket 5 and fastened to the vehicle body. Further, for the other guide portion 82, a rivet 83 provided in the external bracket 5 can be applied. The rivet 83 is attached by penetrating through the pair of side walls 51 and 52 of the external bracket 5 along the Y direction.

[0082] When the EA device 1B is installed on the vehicle body, as shown in Fig. 14, the bolt 71 and the rivet 83 are arranged on the X positive direction side of the pipe 4 of the fixing part 8. Also, the wire 2 is arranged oppositely, sandwiching the wire 2 from both sides in the Y direction at the same position in the X direction. The end position of the bolt 71 on the Z negative direction side is arranged on the Z negative direction side of the cylindrical end on the Z positive direction side of the abutting part 34, and at least a part of the Z positive direction side of the tip of the cylindrical shape of the abutting part 34 can abut. Similarly, the end position of the rivet 83 on the Z positive direction side is arranged on the Z negative direction side of the cylindrical end on the Z negative direction side of the abutting part 34, and at least a part of the Z negative direction side of the tip of the cylindrical shape of the abutting part 34 can abut.

[0083] The bolt 71 and the rivet 83 are formed of a material harder than the external bracket 5 and the pipe 4. That is, the pair of guide parts 81, 82 are formed of a material harder than the external bracket 5 and the pipe 4. Thereby, the strength of the pair of guide parts 81, 82 can be sufficiently ensured, so that when the piston 3 abuts, further movement of the piston 3 in the X positive direction can be reliably restricted.

[0084] Also, a rivet 84 is installed on the external bracket 5 of the fixing part 8 on the Z positive direction side of the fixing hole 56a through which the bolt 71 is inserted. The rivet 84 is attached through the pair of side walls 51, 52 of the external bracket 5 along the Y direction, similarly to the rivet 83. Also, the rivet 84 is arranged oppositely, sandwiching the bolt 71 and the wire 2, at a position closer to the end part 21 side, that is, closer to the buckle 18, than the position where the bolt 71 and the rivet 83 sandwich the wire 2. In the second embodiment, by providing the rivet 84, the direction of the wire 2 is held so that the end part 21 of the wire 2 is inclined and pulled out to the X negative direction side rather than the Z positive direction side.

[0085] Fig. 15 is a perspective view showing the state after the EA device 1B has operated. Fig. 16 is a longitudinal sectional view showing the state after the EA device 1B has operated.

[0086] When a tensile load equal to or greater than a predetermined value acts on the buckle 18 and the wire 2 is pulled in the drawing direction (in the examples of FIGS. 15 and 16, the positive Z direction and the negative Y direction indicated by the arrow M), a load is also transmitted to the cable ferrule 24 fixed to the end portion 22 of the wire 2 on the positive X direction side. As a result, the piston 3B through which the wire 2 is inserted at a position on the positive X direction side of the cable ferrule 24 is pressed toward the positive X direction by the cable ferrule 24, and as shown by the arrow N, the piston 3B moves in the pipe 4 of the fixing portion 8 from the diameter-expanded portion 43 toward the positive X direction.

[0087] Here, the portion of the pipe 4 on the positive X direction side of the diameter-expanded portion 43 is formed with an inner diameter Id1 that is smaller than the inner diameter Id2 of the contact portion 32 and the diameter-expanded portion 43 before the operation of the EA device 1B (in FIG. 16, the original inner diameter Id1 is shown by a dotted line). When a tensile load equal to or greater than a predetermined value is applied to the wire 2 toward the positive X direction, the contact portion 32 of the piston 3B presses the inner peripheral surface of the pipe 4 radially outward as shown by the arrow P, and the inner diameter Id1 of the pipe 4 can be expanded to the same inner diameter Id2 as the contact portion 32 and the diameter-expanded portion 43. As a result, the piston 3B can move in the pipe 4 toward the positive X direction while gradually expanding the pipe 4 from the end portion side in the negative X direction.

[0088] Also, as shown in FIG. 16, when the contact portion 32 of the piston 3B reaches the end portion 41 of the pipe 4 on the positive X direction side, the abutting portion 34 of the piston 3B enters the inside of the outer bracket 5 of the fixing portion 8 and abuts against the outer peripheral surface of the fixing hole 56a through which the pair of guide portions 81, 82, that is, the bolt 71 is inserted, and the rivet 83. As a result, further movement of the piston 3B in the positive X direction is restricted, and movement of the buckle 18 in the tensile direction M is also restricted. As a result, the operation of loosening the webbing 11 accompanying the operation of the EA device 1B is also stopped.

[0089] FIG. 17 is a perspective view of an EA device 1C according to a modified example of the second embodiment. In FIG. 17, as in FIG. 13, the state before the operation of the EA device 1C is illustrated.

[0090] In the EA device 1C shown in FIG. 17, the rivet 84 provided in the EA device 1B of the second embodiment is not provided. As in the EA device 1C of the modification example, at least when the piston 3B moves to the end 41 on the side (X positive direction side) closer to the buckle 18 in the extending direction of the pipe 4 after the operation of the EA device 1C, the tip of the end 41 side of the piston 3B, that is, the tip of the abutting portion 34, may be configured to include a pair of guide portions 81 and 82 that abut, that is, the bolt 71 and the rivet 83.

[0091] As described above, the present embodiment has been described with reference to specific examples. However, the present disclosure is not limited to these specific examples. Those obtained by appropriately making design changes by those skilled in the art to these specific examples are also included in the scope of the present disclosure as long as they have the features of the present disclosure. Each element, its arrangement, conditions, shape, etc. included in each of the above-described specific examples are not limited to those illustrated and can be changed as appropriate. Each element included in each of the above-described specific examples can be changed in combination as appropriate as long as no technical contradiction occurs.

[0092] In the above embodiment, the configuration in which the energy absorption device 1 (hereinafter, also including the energy absorption devices 1A, 1B, and 1C) is applied to the buckle 18 is illustrated. However, for example, a configuration in which the energy absorption device 1 is applied to at least one of the "parts that guide or restrain the webbing 11" in the seat belt device 10, such as the guide anchor 14 and the belt anchor 16, may be used. In other words, the energy absorption device 1 can also be expressed as being a part of the parts that guide or restrain the webbing 11 in the seat belt device 10, such as the belt anchor 16, the guide anchor 14, or the buckle 18.

[0093] For example, when it is desired to absorb the energy of both the lap belt portion and the shoulder belt portion of the webbing 11, the energy absorption device 1 may be disposed only at the buckle 18, or the energy absorption device 1 may be disposed at all of the buckle 18, the belt anchor 16, and the guide anchor 14. On the other hand, when it is desired to absorb only the energy of the lap belt portion of the webbing 11, the energy absorption device 1 may be disposed only at the belt anchor 16, or when it is desired to absorb only the energy of the shoulder belt portion of the webbing 11, the energy absorption device 1 may be disposed only at the guide anchor 14.

Explanation of Signs

[0094] 1, 1A, 1B, 1C Energy absorption device (EA device) 2 Wire 24 Cable ferrule 3, 3A, 3B Piston 31 Hole 32 Contact portion 33 Cable ferrule portion 4 Pipe 41 End portion on the positive X direction side (the other end portion) 42 End portion on the negative X direction side (one end portion) 43 Diameter-expanded portion 5 External bracket (bracket) 6 Internal bracket (connection portion) 81, 82 Pair of guide portions 71 Bolt 83 Rivet 10 Seat belt device 11 Webbing 14 Guide anchor (component for guiding or restraining the webbing) 16 Belt anchor (component for guiding or restraining the webbing) 17 Tongue 18 Buckle (component for guiding or restraining the webbing) Id1 Inner diameter of the pipe Id2 Maximum diameter of the inner diameter of the diameter-expanded portion

Claims

1. An energy absorption device that restricts the load applied to a webbing that restrains an occupant and absorbs and mitigates the energy of the occupant, comprising: a wire having one end connected to a component that guides or restrains the webbing; a piston connected to the other end of the wire; a pipe that houses the piston; wherein the piston is formed such that its diameter continuously increases from a position closer to the component in the extending direction of the pipe along the extending direction away from the component and is larger than the inner diameter of the pipe, and has a contact portion that is arranged in contact with the inner peripheral surface of the pipe and has a curved surface shape that protrudes radially outward; the pipe has a diameter-expanded portion formed by expanding the diameter at one end in the extending direction away from the component so as to have a concave curved surface shape with which the contact portion of the piston can make surface contact; before the operation of the energy absorption device, the contact portion of the piston is installed in the diameter-expanded portion of the pipe; an energy absorption device.

2. The energy absorption device according to claim 1, wherein the curved surface shape of the contact portion is a spherical shape.

3. The piston has a hole that penetrates the other end of the wire, and the energy absorption device has a cable ferrule fixed to the other end of the wire that protrudes from the piston in the extending direction away from the component through the hole.

4. The energy absorption device according to claim 3, wherein the cable ferrule is formed as an integral part with the piston.

5. The piston has a hole through which the other end of the wire passes, and a cable ferrule portion integrally formed with the piston on the side closer to the component in the extending direction with respect to the contact portion, wherein the cable ferrule portion is fixed to the wire whose other end has passed through the hole.

6. After the operation of the energy absorption device, the contact portion of the piston moves to the other end closer to the component in the extending direction of the pipe, the inner diameter of the portion of the pipe excluding the other end is expanded to the maximum diameter of the diameter-expanded portion as the piston moves, and a curved surface having the same shape as the contact portion of the piston is formed at the other end of the pipe.

7. ​ ​ ​ ​ ​ ​ A bracket is disposed between the component and the pipe, and the bracket guides the wire into the pipe by allowing the wire to pass therethrough. After the energy absorption device is actuated, the contact portion of the piston abuts against the connection portion between the pipe and the bracket. The energy absorption device according to claim 1.

8. A bracket is disposed between the component and the pipe, and the bracket guides the wire into the pipe by allowing the wire to pass therethrough. The bracket is formed as an integral part with the pipe. Inside the bracket, a pair of guide portions for guiding the wire are disposed opposite to each other with the wire therebetween at the same position along the moving direction of the piston. The pair of guide portions are formed of a material harder than the bracket and the pipe. After the energy absorption device is actuated and the piston has moved to the other end portion on the side closer to the component in the extending direction of the pipe, the tip portion on the other end side of the piston abuts against the pair of guide portions. The energy absorption device according to claim 1.

9. The pair of guide portions include a bolt inserted into a fixing hole provided in the bracket and fastened to the vehicle body, and a rivet provided in the bracket. The energy absorption device according to claim 8.

10. The energy absorption device is part of a belt anchor, a guide anchor, or a buckle, the energy absorption device according to claim 1.

11. A seat belt device including the energy absorption device according to any one of claims 1 to 10.

Images