JP2018052166A - Seatbelt retractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a seatbelt retractor having a force limiter which can suppress the enlargement of the seatbelt retractor to a center axial line direction of a spool.SOLUTION: In this seatbelt retractor 10, a torsion bar 28 is arranged inside a cylindrical torsion tube 26, and either or both of a connection state of the other side end part of the torsion tube 26 in a center axial line direction and a first head part 46 of a head 32, and a connection state of the other side end part of the torsion bar 28 in a center axial line direction and a second head part 56 of the head 32 are selected. By this constitution, a magnitude of an FL load can be divided into three stages, and the enlargement of the seatbelt retractor 10 in a center axial line direction of a spool 18 can be suppressed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a seat belt retractor capable of absorbing a rotational load in a spool pull-out direction.

  The seat belt retractor includes a force limiter that absorbs a tensile force applied to the webbing from the occupant's body in a vehicle emergency such as a vehicle collision. This type of force limiter includes a torsion bar whose central axis direction is along the central axis direction of the spool. The torsion bar is connected to the spool, and when the spool is rotated in the pull-out direction by the tensile force applied to the webbing in the event of a vehicle emergency, the torsion bar is twisted and deformed by the rotational force of the spool. Part is subjected to torsional deformation of the torsion bar, whereby part of the tensile force is absorbed.

  On the other hand, there is a force limiter in which the thickness of the torsion bar changes stepwise in the direction of the central axis of the torsion bar (see Patent Document 1 below as an example). In such a force limiter, for example, the coupling portion of the torsion bar with the spool changes according to the rotational speed of the spool in the pull-out direction. As a result, the load (tensile force) required to twist and deform the torsion bar, that is, the so-called “FL (force limiter) load” can be changed stepwise.

  By the way, such a force limiter changes the thickness of the torsion bar stepwise in the direction of the central axis of the torsion bar, so that the overall length of the torsion bar along the central axis of the spool becomes long. The seat belt retractor becomes larger in the direction of the center axis of the spool.

JP 2012-214159 A

  In view of the above facts, an object of the present invention is to provide a seat belt retractor including a force limiter that can suppress an increase in the size of the device in the direction of the central axis of the spool.

  The seat belt retractor according to claim 1, wherein the webbing is wound from the base end side and is rotated in the pulling-out direction when the webbing is pulled-out, and is formed in a cylindrical shape and is in the central axis direction A first energy-absorbing member that is deformed by a rotational load greater than or equal to a first force limiter load around a central axis line, wherein one side portion is disposed inside the spool and relative rotation with respect to the spool is limited; The first force limiter load around the central axis is arranged such that one side portion in the central axis direction is coaxial with the first energy absorbing member and is disposed inside the first energy absorbing member and the relative rotation with respect to the spool is limited. Is deformed by a rotational load greater than the second force limiter load having a magnitude different from that of the second force limiter load. An energy absorbing member is selectively engageable with one or both of the other side portion in the central axis direction of the first energy absorbing member and the other side portion in the central axis direction of the second energy absorbing member. A rotation restricting means for restricting rotation of the second energy absorbing member on the other side portion in the central axial direction and the other side portion in the central axial direction of the second energy absorbing member in the pulling direction that is engaged.

  In the seat belt retractor according to claim 1, the cylindrical first energy absorbing member is disposed inside the spool, and the second energy absorbing member is disposed inside the first energy absorbing member. Relative rotation with respect to the spool is restricted at one side portion in the central axial direction of the member and one side portion in the central axial direction of the second energy absorbing member.

  The rotation limiter is engaged with the other side portion of the first energy absorbing member in the central axial direction, and the first energy absorption is performed in a state where rotation of the other side portion of the first energy absorbing member in the central axis direction is limited. When a load in the pulling direction that is equal to or greater than the first force limiter load is applied to the other side portion of the member in the central axis direction, the first energy absorbing member is deformed. For this reason, the load of the magnitude | size of the 1st force limiter load is provided to a deformation | transformation of a 1st energy absorption member among the rotational loads to the pulling-out direction of a spool, and is absorbed.

  On the other hand, the rotation restricting means is engaged with the other side portion of the second energy absorbing member in the central axis direction, and the second energy absorbing member is restricted from rotating in the pull-out direction of the other side portion of the central axis direction of the second energy absorbing member. When a load in the drawing direction that is equal to or greater than the first force limiter load is applied to the other side portion of the energy absorbing member in the central axis direction, the second energy absorbing member is deformed. For this reason, the load of the magnitude | size of a 2nd force limiter load is provided to a deformation | transformation of a 2nd energy absorption member among the rotational loads to the pulling-out direction of a spool, and is absorbed.

  Here, the rotation limiting means is selectively engageable with one or both of the other side portion in the central axis direction of the first energy absorbing member and the other side portion in the central axis direction of the second energy absorbing member. For this reason, the amount of rotational load absorbed in the spool pull-out direction is defined as the magnitude of the first force limiter load, the magnitude of the second force limiter load, and the sum of the first force limiter load and the second force limiter load. You can switch to these three levels.

  Moreover, the second energy absorbing member is disposed coaxially with the first energy absorbing member inside the first energy absorbing member. For this reason, the enlargement of the spool in the direction of the central axis of the first energy absorbing member, and consequently the increase in the size of the seat belt retractor in the direction of the central axis of the spool can be suppressed.

  As described above, in the seat belt retractor according to the present invention, an increase in the size of the device in the central axis direction of the spool can be suppressed.

It is front sectional drawing of the seatbelt retractor which concerns on one embodiment of this invention. FIG. 3 is an exploded perspective view of a spool, a force limiter, and a head with a part of the spool and the torsion tube broken.

  Next, an embodiment of the present invention will be described with reference to FIGS. In each figure, an arrow W1 indicates one side in the apparatus width direction of the seat belt retractor 10, an arrow W2 indicates the other side in the apparatus width direction of the seat belt retractor 10, and an arrow UP indicates the upper side of the apparatus of the seat belt retractor 10. Is shown. 2 indicates the winding direction side around the central axis of the spool 18, and the arrow B direction indicates the drawing direction side around the central axis of the spool 18.

<Configuration of the present embodiment>
If the seat belt retractor 10 is configured to be applied to a driver seat or a passenger seat among vehicle seats (not shown), the seat belt retractor 10 is provided on the vehicle lower side of a vehicle center pillar (not shown). It is done. As shown in FIG. 1, the seat belt retractor 10 includes a frame 12. The frame 12 includes a pair of side plates 14 and 16. The thickness direction of these side plates 14 and 16 is the device width direction (the arrow W1 direction and the arrow W2 direction in FIGS. 1 and 2), and the side plate 14 and the side plate 16 are opposed to each other in the device width direction. Yes. A spool 18 is provided between the side plate 14 and the side plate 16. The spool 18 has a substantially cylindrical shape, and the central axis direction of the spool 18 is the apparatus width direction. The spool 18 is one of the winding directions in the direction around the central axis and the opposite withdrawal direction. The frame 12 is indirectly supported so as to be rotatable in the direction.

  A webbing 20 is provided on the spool 18. The webbing 20 has a long band shape, and the base end portion in the longitudinal direction of the webbing 20 is locked to the spool 18. When the spool 18 is rotated in the winding direction, the webbing 20 is wound around the outer peripheral portion of the spool 18 from the base end side in the longitudinal direction. When the webbing 20 is pulled toward the front end side in the longitudinal direction, the webbing 20 is pulled out from the spool 18 and the spool 18 is rotated in the pull-out direction.

  The front end side of the webbing 20 in the longitudinal direction is drawn from the spool 18 to the upper side of the apparatus. The front end in the longitudinal direction of the webbing 20 drawn from the spool 18 to the upper side of the apparatus is folded back to the lower side of the vehicle by a through anchor (not shown) provided at the upper side of the vehicle center pillar (not shown). Furthermore, the longitudinal direction front-end | tip part of the webbing 20 turned back by the through anchor to the vehicle lower side is latched by the anchor plate (illustration omitted) provided in the vehicle width direction outer side of the sheet | seat.

  A tongue (not shown) is provided in a portion of the webbing 20 between the through anchor and the anchor plate, and the tongue of the webbing 20 is a vehicle in which the tongue is seated in a state where the webbing 20 is hung on the body of an occupant seated on the seat. By being engaged with a buckle (not shown) provided on the center side in the width direction, the webbing 20 is put on the occupant's body.

  On the other hand, a spring unit (not shown) is provided on one side of the side plate 14 of the frame 12 in the apparatus width direction. The spring unit includes urging means such as a mainspring spring. The urging means of the spring unit is coupled to the spool 18 directly or indirectly through another member, and the spool 18 is urged toward the winding direction by the urging means of the spring unit.

  A pretensioner (not shown) is provided on one side of the side plate 14 of the frame 12 in the apparatus width direction. The pretensioner is electrically connected to the ECU 22 shown in FIG. The ECU 22 includes, for example, an acceleration sensor that detects the acceleration of the vehicle, a collision sensor that detects a load from the front side of the vehicle that is applied to the front portion of the vehicle, and the physique of the occupant seated on the seat to which the seat belt retractor 10 is applied. It is electrically connected to various sensors such as a physique sensor to be detected, and an electrical signal output from such a sensor is input to the ECU 22.

  The ECU 22 determines whether or not the vehicle has collided with an obstacle or the like in front of the vehicle based on the signal level of the input electrical signal. When the ECU 22 determines that the vehicle has collided with an obstacle or the like in front of the vehicle, the pretensioner is actuated by the ECU 22, thereby forcibly rotating the spool 18 in the winding direction. As a result, the slight slack (slack) of the webbing 20 hung around the occupant body of the seat is eliminated, and the occupant body can be strongly restrained by the webbing 20.

  On the other hand, the seat belt retractor 10 includes a force limiter 24, and the force limiter 24 includes a torsion tube 26 as a first energy absorbing member. As shown in FIGS. 1 and 2, the torsion tube 26 is formed in a substantially cylindrical shape, and the torsion tube 26 is disposed coaxially with the spool 18 inside the spool 18. One end of the torsion tube 26 in the central axial direction (arrow W1 direction side in FIGS. 1 and 2) is engaged with the spool 18 directly or indirectly through another member, and the center of the torsion tube 26 The relative rotation in the winding direction and the drawing direction with respect to the spool 18 at one end portion in the axial direction is limited.

  This is applied to one end of the torsion tube 26 on the one side in the central axial direction in a state in which the rotation in the pull-out direction of the other end in the central axial direction of the torsion tube 26 (arrow W2 direction in FIGS. 1 and 2) is restricted. Further, the rotational load in the pulling-out direction acts to twist around the central axis of the torsion tube 26. Here, the rigidity, mechanical strength, etc. of the torsion tube 26 are set so that twisting deformation occurs in the torsion tube 26 when the rotational load is equal to or greater than the first force limiter load (hereinafter referred to as the first FL load). Yes.

  Inside the torsion tube 26, a torsion bar 28 as a second energy absorbing member that constitutes the force limiter 24 together with the torsion tube 26 is provided. The torsion bar 28 is formed in a substantially cylindrical shape. The torsion bar 28 is disposed coaxially with the torsion tube 26 and the spool 18 inside the torsion tube 26. One end of the torsion bar 28 in the central axis direction (arrow W1 direction side in FIGS. 1 and 2) is engaged with the spool 18 directly or indirectly through another member such as the torsion tube 26, The relative rotation in the winding direction and the drawing direction with respect to the spool 18 at one end in the central axial direction of the torsion bar 28 is restricted.

  It is applied to one end of the torsion bar 28 in the central axial direction in a state in which the rotation in the pull-out direction of the other end in the central axial direction of the torsion bar 28 (arrow W2 direction in FIGS. 1 and 2) is restricted. Further, the rotational load in the pull-out direction acts to twist around the central axis of the torsion bar 28. Here, the rigidity, mechanical strength, etc. of the torsion bar 28 are set so that twisting deformation occurs in the torsion bar 28 when the rotational load is equal to or greater than the second force limiter load (hereinafter referred to as the second FL load). Yes. Further, the second FL load is made smaller than the first FL load.

  On the other hand, as shown in FIG. 1, the seat belt retractor 10 includes a switching mechanism 30 as rotation limiting means. The switching mechanism 30 includes a head 32, and the head 32 includes a head body 34. The head body 34 includes a cylindrical portion 36. As shown in FIG. 2, the outer peripheral shape of the cylindrical portion 36 is circular. The cylindrical portion 36 is inserted into the spool 18 from the other end in the apparatus width direction of the spool 18. The cylindrical portion 36 inserted inside the spool 18 is disposed coaxially with the spool 18. Further, the cylindrical portion 36 is rotatable relative to the spool 18 in the winding direction and the drawing direction.

  A pawl base 38 is provided on the other side in the apparatus width direction of the cylindrical portion 36 of the head main body 34, and two pawl arrangement portions 40 are formed on the pawl base 38. These pawl arrangement portions 48 are formed around the central axis of the head main body 34 at a predetermined interval. These pawl arrangement portions 40 are provided with ratchet pawls 42 and support pins (not shown). The center axis direction of the support pin (not shown) of the pawl placement portion 40 is the same direction (parallel) as the center axis direction of the spool 18, and the base end portion of the ratchet pawl 42 is the support pin of the pawl placement portion 40. Is rotatably supported.

  Further, as shown in FIG. 1, the pawl base 38 is disposed inside a ratchet hole 44 formed in the side plate 16 of the frame 12, and the tip of the ratchet pawl 42 extends in the rotational radius direction of the spool 18. Opposed to the ratchet teeth of the ratchet hole 44. Further, the ratchet pawl 42 is biased in one direction (in the direction of arrow C in FIG. 2) around the support pin by a pawl biasing member (not shown) such as a torsion coil spring. Therefore, in the initial state of the seat belt retractor 10, the ratchet teeth at the tip of the ratchet pawl 42 mesh with the ratchet teeth in the ratchet hole 44 of the side plate 16. Thereby, in the initial state of the seat belt retractor 10, the head main body 34 can rotate in the winding direction, but the rotation of the head main body 34 in the pull-out direction is limited.

  Further, as shown in FIG. 1, a first head portion 46 is provided inside the head body 34. The first head portion 46 is formed in a substantially cylindrical shape and is arranged coaxially with the spool 18. As shown in FIG. 2, a plurality of outer protrusions 48 are formed on the outer periphery of the first head portion 46. These outer protrusions 48 are formed at a predetermined interval in the circumferential direction of the first head portion 46. Corresponding to these outer protrusions 48, a plurality of head main body groove portions 50 are formed in the inner peripheral portion of the head main body 34. These head main body groove portions 50 contain a plurality of outer protrusions 48 of the first head portion 46. Thereby, the first head unit 46 can move linearly in the apparatus width direction (the direction of the arrow W1 and the direction of the arrow W2 in FIGS. 1 and 2) with respect to the head main body 34, but the head main body of the first head unit 46 The relative rotation in the winding direction and the drawing direction with respect to 34 is limited.

  Further, as shown in FIG. 2, the first head portion 46 is provided with a plurality of first head engaging pieces 52. These first head engaging pieces 52 extend from one end in the apparatus width direction of the first head portion 46 to one side in the apparatus width direction, and are formed at a predetermined interval in the circumferential direction of the first head portion 46. ing. Corresponding to these first head engaging pieces 52, the torsion tube 26 is provided with a plurality of tube engaging pieces 54. These tube engaging pieces 54 extend from the other end in the apparatus width direction of the torsion tube 26 to the other side in the apparatus width direction, and are formed at a predetermined interval in the circumferential direction of the torsion tube 26.

  The tube engaging piece 54 of the torsion tube 26 can enter a gap between the first head engaging pieces 52 adjacent to each other in the circumferential direction in the first head portion 46. Further, the first head engaging piece 52 can enter the gap between the tube engaging pieces 54 adjacent to each other in the circumferential direction in the torsion tube 26. For this reason, the first head portion 46 is relatively moved to one side in the apparatus width direction in a state where the tube engaging piece 54 is opposed to the gap between the first head engaging pieces 52 adjacent in the circumferential direction. Then, the tube engaging piece 54 enters a gap between the first head engaging pieces 52 adjacent to each other. Further, this causes the first head engaging piece 52 to enter the gap between the adjacent tube engaging pieces 54. Thereby, the relative rotation of the torsion tube 26 in the winding direction and the drawing direction with respect to the first head portion 46 is limited.

  On the other hand, a second head portion 56 is provided inside the first head portion 46. The second head portion 56 is formed in a rod shape and is arranged coaxially with the spool 18. A plurality of second head groove portions 58 are formed on the outer peripheral portion of the second head portion 56. These second head groove portions 58 are formed at a predetermined interval in the circumferential direction of the second head portion 56. Corresponding to these second head groove portions 58, a plurality of inner protrusions 60 are formed on the inner peripheral portion of the first head portion 46. These inner protrusions 60 are in a plurality of second head groove portions 58 of the second head portion 56. Thereby, the second head unit 56 can move linearly in the apparatus width direction (the direction of the arrow W1 and the direction of the arrow W2 in FIGS. 1 and 2) with respect to the first head unit 46. The relative rotation in the winding direction and the drawing direction with respect to the first head portion 46 is limited.

  Further, the second head portion 56 is provided with a plus-shaped protrusion 62. The plus-shaped protrusion 62 protrudes from one end in the apparatus width direction of the second head portion 56 toward one apparatus width direction, and the shape of the plus-shaped protrusion 62 viewed from one side in the apparatus width direction is approximately + (Plus) shape. Corresponding to the plus-shaped protrusion 62, the torsion bar 28 is provided with a plus-shaped groove 64. These plus-shaped grooves 64 are formed at the other end in the apparatus width direction, and are opened at the outer peripheral surfaces of the other end in the apparatus width direction of the torsion bar 28 and the other end in the apparatus width direction of the torsion bar 28. Yes.

  The shape of the plus-shaped groove portion 64 of the torsion bar 28 viewed from the other side in the apparatus width direction is a substantially + (plus) shape. The plus-shaped protrusion 62 of the second head portion 56 can enter the plus-shaped groove 64. Therefore, in a state where the phase of the plus-shaped groove 64 around the central axis of the torsion bar 28 matches the phase of the plus-shaped protrusion 62 around the central axis of the second head 56, the second head 56 is When the head portion 46 is slid to one side in the apparatus width direction, the plus-shaped protrusion 62 enters the plus-shaped groove portion 64. Thereby, the relative rotation of the torsion bar 28 in the winding direction and the drawing direction with respect to the second head portion 56 is limited.

  Further, as shown in FIG. 1, an actuator 66 that constitutes the switching mechanism 30 together with the head 32 is located in the vicinity of the other end of the first head portion 46 and the second head portion 56 of the head 32 in the apparatus width direction. Is provided. The actuator 66 includes a first pressing part 68 and a second pressing part 70. When the actuator 66 is actuated to move the first pressing portion 68 to one side in the apparatus width direction, the first head portion 46 of the head 32 is pressed against the first pressing portion 68, thereby the first head. The part 46 is moved to one side in the apparatus width direction.

  Further, when the actuator 66 is actuated to move the second pressing portion 70 to one side in the apparatus width direction, the second head portion 56 of the head 32 is pressed against the second pressing portion 70, thereby The two head portions 56 are moved to one side in the apparatus width direction. Further, the actuator 66 can be operated so as to move only one of the first pressing portion 68 and the second pressing portion 70, and moves both the first pressing portion 68 and the second pressing portion 70. It is also possible to operate.

  The actuator 66 is electrically connected to the battery 74 mounted on the vehicle via the driver 72 and is also electrically connected to the above-described ECU 22 via the driver 72. In the ECU 22, a force limiter load (hereinafter referred to as FL load) required in the event of a vehicle emergency such as a vehicle collision is the sum of the first FL load and the second FL load based on the electrical signals from the above-described sensors. It is determined whether the load is a large load, a medium load that is the first FL load, or a small load that is the second FL load. Based on the determination result, an operation signal is output from the ECU 22, and when the operation signal is input to the driver 72, the driver 72 operates the actuator 66 based on the operation signal.

<Operation and effect of the present embodiment>
Next, the operation and effect of the present embodiment will be described.

In the seat belt retractor 10, for example, when the vehicle is decelerated while the vehicle is running, an electric signal corresponding to the acceleration of the vehicle is output from the acceleration sensor, and this electric signal is input to the ECU 22. Further, when a traveling vehicle collides with an obstacle or the like in front of the vehicle, a load acting on the front side portion of the vehicle from the front side of the vehicle at the time of the vehicle collision is detected by the load sensor, and an electric signal corresponding to the load is output from the load sensor. , Input to the ECU 22. The ECU 22 determines whether or not the vehicle has collided with an obstacle in front of the vehicle based on the input electrical signal.
When it is determined in the ECU 22 that the vehicle has collided with an obstacle in front of the vehicle, the driver 72 operates the actuator 66 based on the operation signal output from the ECU 22, whereby the first pressing portion 68 and the second pressing portion are operated. At least one of the parts 70 is moved to one side in the apparatus width direction.

  In this state, if the first pressing portion 68 of the actuator 66 is moved to one side in the device width direction, the first head portion 46 of the head 32 is pressed by the first pressing portion 68 of the actuator 66 and one side in the device width direction. Moved to. On the other hand, if the second pressing portion 70 of the actuator 66 is moved to one side in the apparatus width direction in this state, the second head portion 56 of the head 32 is pressed by the second pressing portion 70 of the actuator 66. It is moved to one side in the device width direction.

  On the other hand, when the vehicle collides, the occupant's body attempts to move inertially toward the front of the vehicle. For this reason, the webbing 20 is pulled by the occupant's body. When the webbing 20 is pulled in this way and the spool 18 is rotated in the pull-out direction, the torsion tube 26 and the torsion bar 28 are rotated in the pull-out direction together with the spool 18.

  When the torsion tube 26 is rotated in the pull-out direction, the first head engaging pieces 52 of the first head portion 46 of the head 32 are located in the gap between the tube engaging pieces 54 adjacent to each other in the circumferential direction in the torsion tube 26. Opposed. In this state, when the first head portion 46 is moved to one side in the apparatus width direction, the first head engaging piece 52 of the first head portion 46 is located between the adjacent tube engaging pieces 54 in the torsion tube 26. Enter the gap. Accordingly, the tube engaging piece 54 of the torsion tube 26 enters the gap between the first head engaging pieces 52 adjacent to each other in the circumferential direction in the first head portion 46. As a result, the first head portion 46 is connected to the torsion tube 26, and the relative rotation of the torsion tube 26 in the winding direction and the drawing direction with respect to the first head portion 46 is limited.

  In contrast, when the torsion bar 28 is rotated in the pull-out direction, the phase of the plus-shaped groove 64 around the center axis of the torsion bar 28 and the plus-shaped protrusion around the center axis of the second head portion 56 of the head 32. 62 phase matches. In this state, when the second head portion 56 is moved to one side in the apparatus width direction, the plus-shaped protrusion 62 of the second head portion 56 enters the plus-shaped groove portion 64 of the torsion bar 28. As a result, the second head portion 56 is connected to the torsion bar 28, and the relative rotation of the torsion bar 28 in the winding direction and the drawing direction with respect to the second head portion 56 is limited.

  Here, one end of the torsion tube 26 in the central axis direction (arrow W1 direction side in FIGS. 1 and 2) and one end of the torsion bar 28 in the central axis direction (arrow W1 direction side in FIGS. 1 and 2) end The relative rotation in the winding direction and the drawing direction with respect to the spool 18 is limited. Further, the relative rotation of the first head portion 46 of the head 32 in the winding direction and the drawing direction of the head 32 with respect to the head main body 34 is restricted, and the winding of the second head portion 56 of the head 32 with respect to the first head portion 46 is limited. Relative rotation in the direction and withdraw direction is limited. Further, the ratchet teeth of the ratchet pawl 42 mesh with the ratchet teeth of the ratchet hole 44 formed in the side plate 16 of the frame 12, thereby restricting the rotation of the head body 34 in the pull-out direction.

  Therefore, the rotation of the spool 18 in the pull-out direction is performed in at least one of the connection state between the first head portion 46 of the head 32 and the torsion tube 26 and the connection state between the second head portion 56 of the head 32 and the torsion bar. Is limited. As a result, the withdrawal of the webbing 20 from the spool 18 is limited. For example, the body of an occupant trying to move inertially toward the front of the vehicle at the time of a vehicle collision can be effectively restrained by the webbing 20, and the occupant's body toward the front of the vehicle Can be effectively suppressed.

  Further, when the vehicle collides with an obstacle on the front side of the vehicle, at least one of the connection state between the first head portion 46 of the head 32 and the torsion tube 26 and the connection state between the second head portion 56 of the head 32 and the torsion bar. When this happens, the pretensioner is activated. As a result, when the spool 18 is forcibly rotated in the winding direction and the webbing 20 is wound around the spool 18, a slight slack of the webbing 20 hung on the body of the occupant of the seat is caused by a vehicle collision. The webbing 20 can strongly restrain the occupant's body.

  On the other hand, when the occupant's body attempts to move inertially toward the front of the vehicle at the time of a vehicle collision, the webbing 20 is pulled by the occupant's body. As a result, a rotational load in the pull-out direction corresponding to the magnitude of the tensile load applied to the webbing 20 from the occupant's body is applied to the spool 18. Further, this rotational load is transmitted to one end of the torsion tube 26 and the torsion bar 28 in the central axial direction (the direction of the arrow W1 in FIGS. 1 and 2) via the spool 18.

  Here, the ECU 22 determines the FL load required in the event of a vehicle emergency such as a vehicle collision based on the electrical signals output from the sensors such as the physique sensor, the acceleration sensor, and the load sensor when the vehicle collision is determined. The size is determined.

  For example, the ECU 22 determines that a large FL load is necessary, such as when the occupant's physique is large, the vehicle collides with the vehicle running at high speed, or when the acceleration (deceleration) of the vehicle immediately before the vehicle collision is large. Then, the actuator 66 is operated so that both the first pressing part 68 and the second pressing part 70 of the actuator 66 are moved to one side in the apparatus width direction. As a result, the first head portion 46 of the head 32 and the torsion tube 26 are connected, and the second head portion 56 of the head 32 and the torsion bar 28 are connected. In this state, if the rotational load applied to the spool 18 in the pull-out direction is less than the sum of the first FL load and the second FL load, the spool 18 cannot rotate in the pull-out direction. The withdrawal of the webbing 20 is limited.

  On the other hand, when the rotational load applied to the spool 18 in the pull-out direction is greater than or equal to the sum of the first FL load and the second FL load, one end of the torsion tube 26 in the central axial direction is on the other side in the central axial direction. The torsion tube 26 is twisted and deformed so as to rotate in the pull-out direction with respect to the end portion. Further, in this state, one end of the torsion bar 28 in the central axis direction (the arrow W1 direction side in FIGS. 1 and 2) is on the other end in the central axis direction (the arrow W2 direction side in FIGS. 1 and 2). On the other hand, the torsion bar 28 is twisted and deformed so as to rotate in the pull-out direction.

  As a result, the webbing 20 having a length corresponding to the rotation angle of the spool 18 in the pull-out direction is pulled out from the spool 18, and the occupant's body is on the front side of the vehicle by a distance corresponding to the length of the webbing 20 pulled out from the spool 18. It can move to inertia. In addition, by this, of the tensile force applied to the webbing 20 from the occupant's body, a load corresponding to the sum of the first FL load and the second FL load is provided to the torsional deformation of the torsion tube 26 and the torsion bar 28 and absorbed. Is done.

  On the other hand, for example, when the occupant's physique is about the standard body type, when the vehicle collides while driving at medium speed, or when the acceleration (deceleration) of the vehicle just before the vehicle collision is moderate, If the ECU 22 determines that a certain amount of FL load is necessary, the actuator 66 is operated so that only the first pressing portion 68 of the actuator 66 is moved to one side in the apparatus width direction. As a result, the first head portion 46 of the head 32 and the torsion tube 26 are connected. In this state, if the rotational load applied to the spool 18 in the pull-out direction is less than the first FL load, the spool 18 cannot rotate in the pull-out direction, and therefore the pull-out of the webbing 20 from the spool 18 is limited. The

  On the other hand, when the rotational load applied to the spool 18 in the pull-out direction becomes equal to or greater than the first FL load, the end of the torsion tube 26 on one side in the central axis direction (the arrow W1 direction side in FIGS. 1 and 2) The torsion tube 26 is twisted and deformed so as to rotate in the pull-out direction with respect to the other end in the central axis direction (the arrow W2 direction side in FIGS. 1 and 2). As a result, the webbing 20 having a length corresponding to the rotation angle of the spool 18 in the pull-out direction is pulled out from the spool 18, and the occupant's body is on the front side of the vehicle by a distance corresponding to the length of the webbing 20 pulled out from the spool 18. It can move to inertia. In addition, by this, of the tensile force applied to the webbing 20 from the occupant's body, a load corresponding to the first FL load is subjected to torsional deformation of the torsion tube 26 and absorbed.

  Further, for example, when the occupant is small, when the vehicle collides while traveling at a low speed, or when the acceleration (deceleration) of the vehicle just before the vehicle collision is small, the ECU 22 determines that a small FL load is necessary. If determined, the actuator 66 is operated so that only the second pressing portion 70 of the actuator 66 is moved to one side in the apparatus width direction. As a result, the second head portion 56 of the head 32 and the torsion bar 28 are connected. In this state, if the rotational load applied to the spool 18 in the pull-out direction is less than the second FL load, the spool 18 cannot rotate in the pull-out direction, and therefore the pull-out of the webbing 20 from the spool 18 is limited. The

  On the other hand, when the rotational load applied to the spool 18 in the pull-out direction becomes equal to or greater than the second FL load, one end of the torsion bar 28 in the central axial direction (the arrow W1 direction side in FIGS. 1 and 2) The torsion bar 28 is twisted and deformed so as to rotate in the pull-out direction with respect to the end portion on the other side in the central axis direction (arrow W2 direction side in FIGS. 1 and 2). As a result, the webbing 20 having a length corresponding to the rotation angle of the spool 18 in the pull-out direction is pulled out from the spool 18, and the occupant's body is on the front side of the vehicle by a distance corresponding to the length of the webbing 20 pulled out from the spool 18. It can move to inertia. In addition, by this, of the tensile force applied to the webbing 20 from the occupant's body, a load corresponding to the second FL load is subjected to torsional deformation of the torsion bar 28 and absorbed.

  Thus, in the present embodiment, the size of the vehicle is divided into three levels according to the state at the time of the vehicle collision such as the physique of the occupant seated on the seat to which the seat belt retractor 10 is applied, the traveling speed of the vehicle immediately before the vehicle collision, and the like. One FL load can be selected from among the FL loads.

  Further, in the present embodiment, the torsion tube 26 of the force limiter 24 is arranged coaxially with the spool 18 inside the spool 18, and the torsion bar 28 of the force limiter 24 is further inside the torsion tube 26 with respect to the torsion tube 26. It is arranged on the same axis. For this reason, the force limiter 24 has a spool compared to a force limiter in which a plurality of energy absorbing members having different FL loads are arranged in the direction of the central axis of the spool 18 (in the directions of arrows W1 and W2 in FIGS. 1 and 2). An increase in size in the direction of the 18 central axis can be suppressed. Thereby, it can suppress that the seatbelt retractor 10 enlarges to the center axis line direction of the spool 18, ie, an apparatus width direction (the arrow W1 direction and arrow W2 direction of FIG.1 and FIG.2).

  Further, since the torsion bar 28 is disposed inside the torsion tube 26, the installation space for the torsion bar 28 in the spool 18 may not be provided separately from the installation space for the torsion tube 26. As a result, an increase in the size of the spool 18 can be suppressed, and consequently an increase in the size of the seat belt retractor 10 can be suppressed.

  In the present embodiment, the torsion tube 26 is formed in a substantially cylindrical shape. However, as long as the torsion tube 26 has a cylindrical shape, the cross-sectional shape of the torsion tube 26 obtained by cutting the torsion tube 26 in the direction orthogonal to the axis may be a shape other than a circle such as a polygon.

  In the present embodiment, the torsion bar 28 is formed in a substantially cylindrical shape. However, the torsion bar 28 may have a cylindrical shape such as a cylindrical shape. Further, the cross-sectional shape of the torsion bar 28 obtained by cutting the torsion bar 28 in the direction perpendicular to the axis may be a shape other than a circle such as a polygon.

  Further, in the present embodiment, the ratchet teeth at the tip of the ratchet pawl 42 in the initial state of the seat belt retractor 10 are in mesh with the ratchet teeth of the ratchet hole 44 of the side plate 16 of the frame 12. However, for example, in the initial state of the seat belt retractor 10, the ratchet teeth at the tip of the ratchet pawl 42 away from the ratchet teeth of the ratchet hole 44 may be engaged with the ratchet teeth of the ratchet hole 44 in a vehicle emergency.

  In such a configuration, in the initial state of the seat belt retractor 10, the connection state between the first head portion 46 of the head 32 and the torsion tube 26 and the connection between the second head portion 56 of the head 32 and the torsion bar 28. It can be in at least one of the states. In such a configuration, the connection between the first head portion 46 and the torsion tube 26 is eliminated or the second head portion 56 and the torsion bar 28 are removed depending on the magnitude of the FL load required in the event of a vehicle emergency such as a vehicle collision. The connection with is canceled.

  In the present embodiment, the first FL load of the torsion tube 26 is configured to be larger than the second FL load of the torsion bar 28, but the first FL load only needs to be different in magnitude from the second FL load. The first FL load may be smaller than the second FL load.

  Furthermore, in the present embodiment, based on various conditions (levels of electrical signals output from each sensor) such as vehicle acceleration (deceleration) at the time of a vehicle collision, traveling speed of the vehicle at the time of a vehicle collision, and the physique of an occupant. Thus, the ECU 22 operates the actuator 66 to select or switch the FL load. However, for example, whether the vehicle collision mode is a frontal collision or not may be one of the FL load selection conditions or switching conditions, and the vehicle posture at the time of the vehicle collision or after the vehicle collision may be selected as the FL load. One of the conditions or the switching condition may be used, and the FL load selection condition or the switching condition is not limited to the above-described conditions.

10 Seat belt retractor 18 Spool 20 Webbing 26 Torsion tube (first energy absorbing member)
28 Torsion bar (second energy absorbing member)
30 switching mechanism (rotation limiting means)
66 Actuator (Rotation limiting means)

Claims (1)

A cylindrical spool that is wound from the base end side and rotated in the pull-out direction when the webbing is pulled out;
By being formed in a cylindrical shape, one side portion in the central axis direction is disposed inside the spool, relative rotation with respect to the spool is restricted, and a rotational load greater than the first force limiter load around the central axis is applied. A first energy absorbing member to be deformed;
A central axial direction one side portion is disposed on the same axis as the first energy absorbing member and inside the first energy absorbing member, and relative rotation with respect to the spool is limited, and the first force limiter load around the central axis is Is a second energy absorbing member that is deformed by being subjected to a rotational load greater than or equal to a second force limiter load of a different magnitude;
The first energy absorbing member is selectively engageable with one or both of the other side portion in the central axis direction of the first energy absorbing member and the other side portion in the central axis direction of the second energy absorbing member, and the central axis of the first energy absorbing member A rotation limiting means for limiting rotation in the pulling-out direction of the other side portion in the direction and the other side portion in the central axis direction of the second energy absorbing member;
A seat belt retractor comprising: