JP2012020641A - Seat belt device - Google Patents

Abstract

To provide a seat belt device capable of obtaining an appropriate energy absorption characteristic according to a situation when an emergency lock mechanism is operated.
A motor 10 for applying a rotational driving force to a belt reel 12 is provided, and a clutch is provided between the motor 10 and the belt reel 12. Torque limiting means for limiting a torque between the motor 10 and the belt reel 12 by causing a part of the power transmission section to idle with a predetermined resistance when a torque exceeding a predetermined value acts between the motor 10 and the belt reel 12. Is provided. By controlling on / off of the clutch in accordance with the behavior of the occupant after the operation of the emergency lock mechanism 22 and the predicted behavior, it is controlled whether or not an energy absorption function is added by the torque limiting means when the emergency lock mechanism 22 is operated. Absorption energy control means 65 is provided.
[Selection] Figure 1

Description

  The present invention relates to a seat belt device for restraining an occupant seated on a seat by webbing.

2. Description of the Related Art A vehicle seat belt device is known that includes an emergency lock mechanism that mechanically locks a webbing drawer when vehicle behavior becomes unstable in an emergency. Since the emergency lock mechanism locks the webbing drawer suddenly in an emergency, the tension of the webbing acting on the occupant suddenly increases when the occupant tries to move away from the seat due to inertial force.
For this reason, as a means to cope with this, a torsion bar or a plastic deformation member is interposed between the belt reel that winds the webbing and the emergency lock mechanism, thereby reducing the rapid increase in the webbing tension. A seat belt device has been devised (see, for example, Patent Document 1).

  In the seat belt device described in the cited document 1, the belt reel and the emergency lock mechanism are connected via a torsion bar, and the belt reel and the emergency lock mechanism are deformed when both rotate relatively. A plastically deformable member is interposed. In the case of this seat belt device, when the emergency lock mechanism is operated, a rapid increase in the webbing tension is suppressed by the twist of the torsion bar and the deformation of the plastic deformation member.

JP 2006-341711 A

  However, in the case of this conventional seat belt device, once the torsion bar and the plastic deformation member are assembled at the time of manufacture, the operation characteristics (energy absorption characteristics) such as the operation start load and energy absorption stroke are uniformly determined, The characteristics according to the emergency situation are not always obtained.

  Therefore, the present invention is intended to provide a seat belt device capable of obtaining appropriate energy absorption characteristics according to the situation at the time of operation of the emergency lock mechanism.

The seat belt device according to the present invention employs the following means in order to solve the above problems.
The invention according to claim 1 is a webbing that restrains an occupant seated in a seat (for example, the webbing 5 of the embodiment), a belt reel (for example, the belt reel 12 of the embodiment) around which the webbing is wound, and a vehicle. An emergency lock mechanism (for example, the emergency lock mechanism 22 of the embodiment) that locks rotation in the pull-out direction of the belt reel when the belt is in an emergency state, and is interposed between the emergency lock mechanism and the belt reel, When the emergency lock mechanism is activated, an energy absorbing means (for example, the torsion bar 30 of the embodiment) that absorbs excessive torque that acts between the emergency lock mechanism and the belt reel. A motor (for example, the motor 10 of the embodiment) that applies a rotational driving force to the belt reel, the motor, and the bell A clutch (for example, the clutch 20 of the embodiment) provided in a power transmission unit between the reels and configured to connect and disconnect power transmission between the motor and the belt reel, and a predetermined value between the motor and the belt reel. Torque limiting means for limiting a torque between the motor and the belt reel by causing a part of the power transmission unit to idle with a predetermined resistance when a torque exceeding the torque is applied (for example, the large-diameter gear 56A of the embodiment). , Small-diameter gear 56B, spring plate 58) and the on / off control of the clutch according to the behavior of the occupant after the operation of the emergency lock mechanism or the predicted behavior. Absorption energy control means for controlling whether or not an energy absorption function is added by the torque limiting means (for example, the absorbed energy of the embodiment) And control means 65), characterized in that is provided.
As a result, when the emergency lock mechanism is activated, the absorbed energy control means controls on / off of the clutch according to the actual behavior or predicted behavior of the occupant at that time. If the clutch is off when the emergency lock mechanism is activated, the energy absorbing means interposed between the emergency lock mechanism and the belt reel functions independently. Further, when the clutch is turned on during operation of the emergency lock mechanism, an energy absorbing function by the torque limiting means on the motor side is added in addition to the energy absorbing means. Therefore, when the emergency lock mechanism is activated, the energy absorption characteristics are switched according to the actual behavior or predicted behavior of the occupant.

According to a second aspect of the present invention, in the seat belt device according to the first aspect, the absorbed energy control means disengages the clutch when the webbing withdrawal speed immediately after the operation of the emergency lock mechanism is greater than a threshold speed. It is characterized by being turned on.
Thus, when the emergency lock mechanism is activated, when the occupant moves fast and the webbing is pulled out at a speed greater than the threshold speed, the clutch is controlled to be turned on by the absorbed energy control means, and the energy absorbing means and the torque limiting means are Both will work.

The invention according to claim 3 is the seat belt device according to claim 2, wherein the threshold speed is adjusted so as to decrease as the absolute value of the acceleration acting on the vehicle in an emergency increases.
As a result, when the absolute value of the acceleration acting on the vehicle in an emergency is large, the threshold acceleration becomes small, and the energy absorption characteristic by the torque limiting means is added from the stage where the webbing withdrawal speed is relatively slow.

The invention according to claim 4 is the seat belt device according to any one of claims 1 to 3, wherein the absorbed energy control means turns on the clutch when the airbag is not deployed in an emergency. It is characterized by.
As a result, when the airbag is not deployed in an emergency and the occupant's behavior is expected to increase, the clutch is controlled to be turned on by the absorption energy control means so that both the energy absorption means and the torque limiting means function. Become.

  According to the first aspect of the present invention, when the emergency lock mechanism is activated, the absorbed energy control means controls on / off of the clutch according to the actual behavior or predicted behavior of the occupant at that time, and thereby the energy absorbing means Since the simultaneous operation of the energy absorption means and the torque limiting means can be selected, an appropriate energy absorption characteristic can be obtained according to the situation when the emergency lock mechanism is activated.

  According to the invention of claim 2, when the upper body movement of the occupant in an emergency is fast and the webbing withdrawal speed immediately after the operation of the emergency lock mechanism is larger than the threshold speed, the clutch is turned on and the energy absorbing means and the torque are turned on. Since the limiting means are operated simultaneously, a large amount of energy accompanying the movement of the occupant's body can be reliably absorbed by the energy absorbing means and the torque limiting means.

  According to the invention according to claim 3, since the threshold acceleration for switching on the clutch is adjusted to be smaller as the absolute value of the acceleration acting on the vehicle in an emergency is larger, the situation where the vehicle behavior changes more rapidly. The addition of the energy absorption function by the torque limiting means can be obtained at an early stage.

  According to the invention of claim 4, when the airbag is not deployed in an emergency and the occupant's behavior is expected to increase, the clutch is turned on and the energy absorbing means and the torque limiting means are operated simultaneously. The large energy accompanying the occupant's body movement can be reliably absorbed by the energy absorbing means and the torque limiting means.

1 is a schematic configuration diagram of a seat belt device according to a first embodiment of the present invention. It is a disassembled perspective view of the emergency lock mechanism of the seatbelt apparatus of 1st Embodiment of this invention. It is a disassembled perspective view of the 1st pretensioner of the seatbelt apparatus of 1st Embodiment of this invention. It is a front view in the 1st pretensioner corresponding to A arrow of FIG. 3 of the seatbelt apparatus of 1st Embodiment of this invention. It is a front view corresponding to the A arrow of FIG. 3 of the clutch part of the seatbelt apparatus of 1st Embodiment of this invention. It is a front view in the 1st pretensioner corresponding to A arrow of FIG. 3 of the seatbelt apparatus of 1st Embodiment of this invention. It is a flowchart which shows the flow of control of the seatbelt apparatus of 1st Embodiment of this invention. It is a graph which shows the energy absorption characteristic at the time of the action | operation of the emergency lock mechanism of the seatbelt apparatus of 1st Embodiment of this invention. It is a perspective view which shows schematic structure of the seatbelt apparatus of 2nd Embodiment of this invention. It is a disassembled perspective view of the energy absorption mechanism of the seatbelt apparatus of 2nd Embodiment of this invention. It is a disassembled perspective view of the energy absorption mechanism of the seatbelt apparatus of 2nd Embodiment of this invention. It is a front view of the energy absorption mechanism of the seatbelt apparatus of 2nd Embodiment of this invention. It is the perspective view fractured | ruptured by the BB part of FIG. 11 of the seatbelt apparatus of 2nd Embodiment of this invention. It is the perspective view fractured | ruptured by the BB part of FIG. 11 of the seatbelt apparatus of 2nd Embodiment of this invention. It is a graph which shows the energy absorption characteristic at the time of the action | operation of the emergency lock mechanism of the seatbelt apparatus of 2nd Embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram illustrating a schematic configuration of a seat belt device 1, and reference numeral 2 in the drawing denotes a seat on the driver's seat on which an occupant 3 is seated.
The seat belt device 1 is a so-called three-point seat belt, and a webbing 5 is drawn upward from a retractor 4 attached to a center pillar (not shown), and the webbing 5 is supported on the upper side of the center pillar 6. And the tip of the webbing 5 is fixed to the vehicle body floor via an outer anchor 7 on the outer side of the passenger compartment of the seat 2. A tongue plate 8 is inserted between the through anchor 6 and the outer anchor 7 of the webbing 5, and the tongue plate 8 can be attached to and detached from the buckle 9 fixed to the vehicle body floor of the seat 2 on the inner side of the vehicle body. It has become.

The webbing 5 is wound around the retractor 4 in the initial state, and the occupant 3 pulls it out by hand to fix the tongue plate 8 to the buckle 9, thereby restraining the chest and abdomen mainly of the occupant 3 with respect to the seat 2. To do.
Further, the retractor 4 of the seat belt device 1 includes a first pretensioner 50 that winds the webbing 5 using the driving force of the electric motor 10 when the vehicle behavior becomes unstable, etc., and a gas generator (not shown) And a second pretensioner 70 that winds the webbing 5 using the thrust. The first pretensioner 50 is provided with a motor 10 for restraining the occupant 3 to the seat 2 when the vehicle behavior becomes unstable, for example, when the vehicle is suddenly braked, skids, a light collision, or when the impact is reduced before the collision. The second pretensioner 70 pulls the webbing 5 by the thrust of the gas generator to instantly restrain the occupant 3 to the seat 2 when a large impact is input to the vehicle as in the case of a vehicle collision. Pull in. The driving of the motor 10 of the first pretensioner 50 and the operation of the gas generator of the second pretensioner 70 are controlled by the controller 21.

  In the retractor 4, a webbing 5 is wound around a belt reel 12 that is rotatably supported by a casing 14. The belt reel 12 is connected to the motor 10 via a power transmission mechanism 13 (49 in FIG. 1 indicates a gear case that houses the power transmission mechanism 13), which will be described later. Further, the retractor 4 is provided with a winding spring (not shown) that urges the belt reel 12 in the webbing winding direction. When the belt reel 12 and the motor 10 are separated by a clutch 20 described later, the retractor 4 Tension acts on the webbing 5.

The controller 21 receives a signal from the rotation sensor 11 that detects the rotational position of the belt reel 12, a signal from a front state detection device 48 that detects the proximity state of an object in front of the vehicle such as a millimeter wave radar, A signal from the acceleration sensor 40 that detects the acceleration of the vehicle, a signal from the SRS unit 41 that informs whether an airbag (not shown) is activated, a signal from the vehicle speed sensor 42, the brake sensor 43, the buckle switch 44, and the like are input. Is done.
The controller 21 determines an emergency state (an unstable state of the vehicle behavior) based on input signals from the front state detection device 48, the acceleration sensor 40, the vehicle speed sensor 42, the SRS unit 41, the brake switch 43, the buckle switch 44, and the like. When it is determined that the vehicle is in an emergency state, the motor 10 of the first pretensioner 50 is energized and controlled so that the webbing 5 is pulled in largely or intermittently. When the determination is made, the gas generator of the second pretensioner 70 is operated.

  The retractor 4 has a belt when a deceleration (acceleration) of a predetermined value or more acts on the vehicle (when the vehicle behavior becomes unstable) or when the webbing 5 is about to be pulled out suddenly. An emergency lock mechanism 22 that mechanically locks the rotation of the reel 12 in the webbing pull-out direction is provided.

FIG. 2 shows details of the emergency lock mechanism 22 provided in the retractor 4.
The casing 14 of the retractor 4 is provided with a pair of side walls 14A and 14B. The first pretensioner 50 and the second pretensioner 70 are attached to one side wall 14A, and the other side wall 14B will be described later. A retainer 24 that supports the lock operation drum 23 is attached. Further, a substantially circular hole 25 is provided in the side walls 14A and 14B on both sides, and a lock groove 26 inclined in the webbing take-up direction is formed on the inner periphery of the hole 25 in the other side wall 14B.

A torsion bar 30 that is an energy absorbing member is inserted through the inner peripheral side of the belt reel 12. One end of the torsion bar 30 is fixed to one end in the axial direction of the belt 12, and the other end 30 a of the torsion bar 12. Protrudes outward from the other axial end of the belt reel 12. A locking base 27 is integrally fixed to the other end 30 a of the torsion bar 30, and a lock operation drum 23 is fitted to the other end 30 a of the torsion bar 30 that passes through the locking base 27. The lock operation drum 23 is fitted to the other end 30a of the torsion bar 30 with a small frictional resistance, and rotates integrally with the lock king base 27 during normal rotation of the belt reel 12, and the locking base 27 and the lock operation drum 23 are When a large rotational force is applied between them, it rotates relative to the locking base 27 within a set angle range. A swing arm 28 having a lock claw 28a is swingably attached to a position separated from the rotation center of the locking base 27.
When the tip end side lock claw 28a swings radially outward and protrudes, the swing arm 28 engages with the lock groove 26 on the casing 14 side. The swing arm 28 meshes with the lock groove 26 inclined in the webbing winding direction, thereby locking the rotation of the belt reel 12 in the pulling direction and allowing the belt reel 12 to rotate in the winding direction. The swing arm 28 is provided with a guide protrusion 29 that protrudes in the direction of the lock operation drum 23.

The lock actuating drum 23 has a plurality of clutch teeth 32 projecting from the outer peripheral surface, and a cam hole 31 inclined with respect to the normal direction is provided on the disc surface in the central region so as to penetrate in the plate thickness direction. Yes. A guide projection 29 of the swing arm 28 is slidably fitted into the cam hole 31.
When the belt reel 12 (locking base 27) rotates relative to the lock operation drum 23 in the webbing pull-out direction, the guide protrusion 29 causes the lock claw 28a of the swing arm 28 to move in the radial direction by the guide action of the cam hole 31. Project outward. Thus, when the lock claw 28a of the swing arm 28 protrudes radially outward, the lock claw 28a is engaged with the lock groove 26 on the casing 14 side (locked). Further, from this state, when the belt reel 12 rotates relative to the lock operation drum 23 in the webbing take-up direction, the lock claw 28a of the swing arm 28 is similarly pulled back radially inward by the guide action by the cam hole 31. Thus, when the lock claw 28a of the swing arm 28 is pulled back inward in the radial direction, the engagement of the lock claw 28a with the lock groove 26 is released (the locked state is released).

  A centrifugal arm 33 is swingably attached to the disk surface of the lock operation drum 23. The centrifugal arm 33 is composed of a mass body that is greatly influenced by centrifugal force, and is attached to a position spaced from the rotation center of the lock operation drum 23 so as to be swingable. The centrifuge arm 33 is provided with a lock claw 34 on the arm tip side, receives a centrifugal force according to the rotation of the lock operation drum 23, and swings the lock claw 34 side outward in the radial direction. A biasing spring 35 is provided between the lock actuating drum 23 and the centrifugal arm 33 to urge the lock claw 34 side of the centrifugal arm 33 in the radially inward direction of the lock actuating drum 23 at all times.

  The retainer 24 is provided therein with a bearing structure (not shown) that rotatably supports the shaft portion of the lock operating drum 23, and a clutch (not shown) having an internal tooth structure so as to face the outer peripheral side of the lock claw 34 of the centrifugal arm 33. Teeth are provided. When the centrifugal arm 33 swings outward in the radial direction due to the centrifugal force, the lock claw 34 of the centrifugal arm 33 meshes with the clutch teeth of the retainer 24. The lock actuating drum 23 is thus locked in rotation, and when the webbing 5 is about to be pulled out from this state (the belt reel 12 is about to rotate in the webbing pull-out direction), as described above, the lock claw of the swing arm 28 is locked. 28a is engaged with the lock groove 26 on the casing 14 side (emergency lock mechanism 22 is locked).

In addition, a vehicle sensor 37 is provided at a position below the lock actuating drum 23 in the retainer 24 to operate the locking claw 36 by detecting the deceleration (acceleration) and inclination of the vehicle. In the vehicle sensor 37, a sensor weight 45 is disposed in a housing portion surrounded by a sensor case 38 and a sensor cap 39, and a locking claw 36 is integrally attached to the sensor weight 45. The sensor weight 45 swings according to the acceleration and inclination of the vehicle, and engages the locking claw 36 with the clutch teeth 32 of the lock operation drum 23 when the sensor weight 45 swings more than a specified amount.
Thus, when the locking claw 36 is engaged with the clutch tooth 32, the rotation of the lock operation drum 23 is locked. Accordingly, when the webbing 5 is to be pulled out in this state, the lock claw 28a of the swing arm 28 is engaged with the lock groove 26 on the casing 14 side (the emergency lock mechanism 22 is locked).

  Here, after the emergency lock mechanism 22 locks the rotation of the belt reel 12 in the webbing pull-out direction as described above, the locked state is released when the belt reel 12 is rotated more than a predetermined amount in the webbing take-up direction. The That is, when the belt reel 12 rotates in the webbing take-up direction with the rotation of the lock operation drum 23 stopped, the relative positional relationship between the belt reel 12 and the lock operation drum 23 is returned to the initial position. 29 and the cam hole 31, the lock claw 28a of the swing arm 28 is pulled back, and as a result, the engagement with the lock claw 28 and the lock groove 2 is released (the emergency lock mechanism 22 is unlocked). ).

FIG. 3 is an exploded perspective view showing components of the first pretensioner 50, and FIG. 4 is a front view showing a schematic arrangement of components of the first pretensioner 50.
As shown in FIG. 1, the first pretensioner 50 is installed on the side wall 14 </ b> A side of the housing 14 with the second pretensioner 70 interposed therebetween. As shown in FIG. 3, the gear case 49 that accommodates the power transmission mechanism 13 includes a case main body 49A that is installed on the second pretensioner 70, and a case cover 49B that covers the front surface of the case main body 49A. A motor 10 is installed on one end side (lower side in FIG. 3) of 49, and a ratchet gear 51 is rotatably accommodated on the other end side (upper side in FIG. 3) in the gear case 49. The ratchet gear 51 is coupled to one end portion of the belt reel 12 via a connecting shaft (not shown) penetrating the second pretensioner 70 so as to be integrally rotatable, and a ratchet tooth 51a to which a pawl 52 described later is engaged on the outer peripheral portion. Is formed.

  In the gear case 49, a pinion gear 53 coupled to the rotation shaft of the motor 10, a ring gear 54 disposed coaxially with the ratchet gear 51 on the outer peripheral side of the ratchet gear 51, and a pinion gear 53 and a ring gear 54 are interposed. The first to third transmission gears 55, 56, and 57 that are mounted and decelerate the rotation of the motor 10 and transmit it to the ring gear 54 are accommodated. In the first transmission gear 55, a large-diameter gear 55A meshed with the pinion gear 53 and a small-diameter gear 55B having an outer diameter smaller than that of the large-diameter gear 55A are integrally provided coaxially.

  The second transmission gear 56 includes a large-diameter gear 56A meshed with the small-diameter gear 55B of the first transmission gear 55 and a small-diameter gear 56B meshed with the third gear 57. The large-diameter gear 56A and the small-diameter gear 56B of the second transmission gear 56 are configured as separate parts, the large-diameter gear 56A is formed in a bottomed cylindrical shape, and the small-diameter gear 56B is disposed on the inner peripheral side of the large-diameter gear 56A. A substantially cylindrical tubular wall 56Ba is provided. A plurality of spring plates 58 having bent protrusions 58a are attached to the outer peripheral portion of the cylindrical wall 56Ba, and the spring plates 58 are accommodated together with the cylindrical wall 56Ba on the inner peripheral side of the large-diameter gear 56A. On the inner peripheral surface of the large-diameter gear 56A, a plurality of recesses 56Aa that engage with the bent protrusions 58a of the spring plate 58 are provided.

  The large-diameter gear 56A and the small-diameter gear 56B are normally coupled together via a spring plate 58, but if a torque exceeding a predetermined value acts between the large-diameter gear 56A and the small-diameter gear 56B, the spring plate 58... Bend projection 58a slides on the inner peripheral surface of large-diameter gear 56A, thereby limiting torque transmission to a predetermined value or less. The large diameter gear 56A and the small diameter gear 56B are idled with a predetermined resistance while the bending protrusion 58a slides on the inner peripheral surface of the large diameter gear 56A. In this embodiment, the large-diameter gear 56A, the small-diameter gear 56B, the spring plate 58, and the like of the second transmission gear 56 constitute torque limiting means that limits the torque between the motor 10 and the belt reel 12. Hereinafter, this torque limiting means is referred to as torque limiting means by the second transmission gear 56.

  By the way, a ring plate 54 that is disposed coaxially with the ratchet gear 51 in the gear case 49 is attached with a ring plate 59 so as to form the bottom surface of the ring gear 54, and the base of the pawl 52 described above has a diameter on the ring plate 59. It is supported so that it can swing in the direction. The front end portion of the pawl 52 can mesh with the ratchet teeth 51 a of the ratchet gear 51 by the rocking displacement of the pawl 52 radially inward. In this meshing state, the rotation of the ring gear 54 in the webbing take-up direction is transmitted to the ratchet gear 51, but the rotation of the ring gear 54 in the webbing withdrawal direction is not transmitted to the ratchet gear 51. A return spring 60 is provided between the ring plate 59 and the pawl 52, and the tip end of the pawl 52 is always urged radially outward by the return spring 60.

A guide ring 62 that holds the cam plate 61 is disposed on the inner peripheral side of the ring gear 54 so as to be relatively rotatable. The cam plate 61 is disposed opposite to the tip end side of the pawl 52, and guides the rocking displacement of the pawl 52 according to the relative rotation of the ring gear 54 and the guide ring 62. A step is provided on each of the inner periphery of the ring gear 54 and the outer periphery of the guide ring 62, and the relative rotation angle between the ring gear 54 and the guide ring 62 is regulated within a predetermined angle range by contacting these steps. ing. Further, both end portions of a substantially C-shaped friction spring 63 for applying a resilient force in the diameter increasing direction are fixed to the case main body 49A of the gear case 49. The outer peripheral surface of the friction spring 63 is in contact with the inner peripheral surface of the guide ring 62 with a predetermined frictional resistance.
In this embodiment, the clutch 20 for connecting / disconnecting the power transmission between the motor 10 and the belt reel 12 includes a pawl 52, a return spring 60, a cam plate 61, a friction spring 63, a ratchet gear 51, and the like. ing. As will be described later, the clutch 20 of this embodiment turns on the power transmission by the rotation of the motor 10 in the normal rotation direction (the direction in which the belt reel 12 is rotated in the webbing take-up direction), and the motor 10 rotates in the reverse direction. The power transmission is turned off in response to the rotation of.

FIG. 5 is a diagram showing an internal state of the ring gear 54 when the motor 10 is in an inoperative state.
As shown in the figure, when the motor 10 is not operated, the rotation of the ring gear 54 is stopped, and the pawl 52 is flipped up radially outward by the force of the return spring 60, and the tip of the pawl 52 is The ratchet gear 51 is not engaged. Therefore, at this time, the belt reel 12 is completely disconnected from the motor 10, and the clutch 20 is in an off state.

  From this state, when the motor 10 is driven in the forward rotation direction (see the solid line arrow in FIG. 4), the rotation of the pinion gear 53 causes the first transmission gear 55, the second transmission gear 56, and the third transmission gear 57 to rotate. The ring gear 54 is sequentially transmitted to the ring gear 54, and the ring gear 54 rotates in the webbing take-up direction M. As a result, the ring gear 54 rotates relative to the guide ring 62 locked to the gear case 49 by the frictional resistance of the friction spring 63. Thus, when the ring gear 54 rotates to one side with respect to the guide ring 62, the pawl 52 on the ring gear 54 side comes into contact with the cam plate 61 on the guide ring 62 side, and the tip of the pawl 52 is guided radially inward, As shown in FIG. 4, the tip end portion of the pawl 52 is engaged with the ratchet teeth 51 a of the ratchet gear 51. Therefore, at this time, the belt reel 12 is connected to the motor 10 and the clutch 20 is turned on. Thereby, the rotation of the ring gear 54 in the forward direction is transmitted to the belt reel 12 through the ratchet gear 51, and the belt reel 12 rotates in the webbing take-up direction M.

  Thus, once the clutch 20 is turned on, the meshing state of the pawl 52 and the ratchet gear 51 is maintained even after the driving of the motor 10 is stopped. When the pinion gear 53 is driven, the rotation of the pinion gear 53 is transmitted to the ring gear 54 via the first, second, and third transmission gears 55, 56, and 57 sequentially, and the ring gear 54 rotates in the reverse direction. To come. As a result, the ring gear 54 rotates relative to the guide ring 62 locked to the gear case 49 by the frictional resistance of the friction spring 63 in the other direction. Thus, when the ring gear 54 rotates to the other side with respect to the guide ring 62, the pawl 52 on the ring gear 54 side is separated from the cam plate 61, the engagement between the tip end portion of the pawl 52 and the ratchet gear 51 is disengaged. As shown in FIG. 5, it is returned to the initial state by the force of the return spring 60. As a result, the clutch 20 is turned off.

  By the way, when the motor 10 is driven in an emergency, the driving force of the motor 10 may be transmitted to the belt reel 12 and the webbing 5 may be taken up suddenly. At this time, a predetermined amount is provided between the motor 10 and the belt reel 12. When a torque exceeding the value is applied, the torque limiting means by the second transmission gear 56 functions to cause the large diameter gear 56A and the small diameter gear 56B to idle with a predetermined resistance.

In the case of this seat belt device 1, when the emergency lock mechanism 22 is activated, the torque limiting means by the second transmission gear 56 is appropriately activated according to the upper body behavior of the occupant 3 and whether the airbag is activated. Yes.
Specifically, as shown in FIG. 1, the controller 21 includes a pulling speed of the webbing 5 (rotational speed in the pulling direction of the belt reel 12) and an air bag from the SRS unit 41 when the emergency lock mechanism 22 is operated. Absorption energy control for controlling whether or not the energy transmission function of the torque limiting means by the second transmission gear 56 is added by controlling on / off of the clutch 20 (operation of the motor 10) according to the presence or absence of the operation signal. Means 65 are provided. The absorbed energy control means 65 is associated with torsion of the torsion bar 30 when the airbag is not activated when the emergency lock mechanism 22 is activated and when the webbing 5 is pulled out at a speed higher than the threshold speed even when the airbag is activated. In addition to the energy absorbing function, the torque absorbing function of the torque limiting means by the second transmission gear 56 is added, and the energy absorbing function by the torsion bar 30 is made to act independently under other conditions.
In the case of this embodiment, the threshold speed of the webbing 5 changes according to the absolute value of the acceleration that acts on the vehicle in an emergency, and decreases as the absolute value of the acceleration that acts on the vehicle increases. The absorption energy control means 65 is set to add an energy absorption function by the torque limiting means at an early stage.

FIG. 6 shows the state of torque transmission in the first pretensioner 50 when the clutch 20 is turned on when the emergency lock mechanism 22 is operated and the energy absorbing function of the torque limiting means by the second transmission gear 56 is added. FIG.
As shown in the figure, when the motor 10 is rotated forward during the operation of the emergency lock mechanism 22, the pawl 52 meshes with the ratchet gear 51 as the ring gear 54 rotates in the forward rotation direction as described above. The belt reel 12 is connected. In this state, the reaction torque (force in the direction in which the webbing 5 is pulled out) accompanying the upper body movement of the occupant 3 passes through the belt reel 12, the ratchet gear 51, and the pawl 52, and is applied to the ring gear 54 as indicated by an arrow H in FIG. When transmitted, the torque is input to the small-diameter gear 56B of the second transmission gear 56 via the third transmission gear 57. On the other hand, the torque in the webbing winding direction of the motor 10 is input from the pinion gear 53 to the large-diameter gear 56 </ b> A of the second transmission gear 56 via the first transmission gear 55. Accordingly, if the reaction torque transmitted to the small-diameter gear 56B of the second transmission gear 56 exceeds a predetermined value at this time, the idle rotation with a predetermined resistance between the small-diameter gear 56B and the large-diameter gear 56A via the spring plate 58 is achieved. In this case, a part of the drawing energy of the webbing 5 is absorbed by idling with resistance.

Next, an example of control by the controller 21 when the emergency lock mechanism 22 is operated will be described with reference to the flowchart of FIG.
In step S101, it is determined whether or not a vehicle collision has occurred based on signals from the forward state detection device 48 and the acceleration sensor 40. If yes, the process proceeds to the next step S102, and if no, To return.
In step S102, it is determined whether or not the airbag operates based on a signal from the SRS unit 41. If yes, the process proceeds to step S103, and if no, the process proceeds to step S104. . If it is determined that the airbag does not operate and the routine proceeds to step S104, it is predicted that the movement stroke of the occupant's upper body to the front side will increase, so the clutch 20 is turned on (the motor 10 is turned on). By driving forward, the force acting on the belt reel 12 from the webbing 5 (reaction force of the occupant 3) is absorbed by the torsion of the torsion bar 30 and the energy absorbing function of the torque limiting means by the second transmission gear 56. .
In step S103, the drawing speed threshold value Va of the webbing 5 is set according to the absolute value of the acceleration currently acting on the vehicle, and then the process proceeds to the next step S105.
In step S105, it is determined whether or not the current drawing speed V of the webbing 5 is equal to or higher than the speed threshold Va set in step S105. If yes, the process proceeds to step S106, and if no, Return. In the case of returning here, since the energy absorbing function of the torque limiting means by the second transmission gear 56 is not added, the force acting on the belt reel 12 from the webbing 5 is absorbed solely by the torsion of the torsion bar 30 alone. .
On the other hand, when the drawing speed V of the webbing 5 is equal to or higher than the speed threshold Va and the process proceeds to step S106, the moving speed of the upper body of the occupant 3 is fast, so the clutch 20 is turned on (the motor 10 is driven forward). Thus, the force acting on the belt reel 12 from the webbing 5 is absorbed by the twist of the torsion bar 30 and the energy absorbing function of the torque limiting means by the second transmission gear 56.

  FIG. 8 is a graph showing two types of energy absorption characteristics (A) and (B) when the emergency lock mechanism 22 of the seat belt device 1 is operated. In the seat belt device 1, the two types of energy absorption characteristics are appropriately selected according to the operating state of the emergency lock mechanism 22.

  In the seat belt device 1 according to this embodiment, the clutch 20 depends on the actual behavior of the occupant 3 (the pulling speed of the webbing 5) and the predicted behavior of the occupant (whether the seat bag is activated) when the emergency lock mechanism 22 is activated. Since the torsion bar 30 can be functioned independently by controlling on / off of the motor, or the torsion bar 30 and the torque limiting means on the motor 10 side can be functioned together, the emergency lock mechanism 22 is activated. Appropriate energy absorption characteristics can be obtained according to the situation of the time. Further, since the energy absorption by the torque limiting means on the motor 10 side can arbitrarily control the start timing and the end timing by controlling the clutch 20, more appropriate energy absorption characteristics can be easily obtained.

  In the seat belt device 1, the upper body movement of the occupant 3 in an emergency is fast, and when the pulling speed of the webbing 5 immediately after the operation of the emergency lock mechanism 22 is larger than the threshold speed Va, the torsion bar 30 and the motor 10. Since the torque limiter on the side functions together, it is possible to absorb a large amount of energy for moving the body of the occupant 3 quickly and reliably.

  In particular, in this embodiment, the threshold speed Va is not always constant, and the threshold acceleration Va is set so as to decrease as the absolute value of the acceleration acting on the vehicle increases. Therefore, the vehicle behavior changes rapidly due to a large collision. The more the situation is, the faster the timing of adding the energy absorption function by the torque limiting means, and the larger energy absorption can be executed at an early stage.

  Further, in the seat belt device 1, when the airbag is not activated in an emergency and the behavior of the occupant 3 is predicted to increase, the torsion bar 30 and the torque limiting means on the motor 10 side function together. The energy can be absorbed quickly and reliably under a situation where the upper body travel stroke of the occupant 3 is large.

Next, a second embodiment shown in FIGS. 9 to 15 will be described.
The seat belt device 101 of this embodiment is different from the first embodiment in that an energy absorbing mechanism 80 that can act in parallel with the torsion bar 30 is added when the emergency lock mechanism 22 is operated. It is almost the same as that of the first embodiment. Therefore, in the following description, the added energy absorbing mechanism 80 will be mainly described, the same parts as those in the first embodiment will be denoted by the same reference numerals, and a part of overlapping description will be omitted.

FIG. 9 is a diagram showing an overall schematic configuration of the seat belt device 101, and FIGS. 10 to 12 are diagrams showing a configuration of the energy absorbing mechanism 80.
As shown in FIG. 9, the energy absorbing mechanism 80 is disposed on the other side wall 14 b side of the casing 14. The energy absorbing mechanism 80 is a belt-shaped energy absorbing member 81 (hereinafter referred to as a belt-shaped energy absorbing member 81) that absorbs energy by plastic deformation when the belt reel 12 tries to rotate with a torque of a predetermined value or more with respect to the locking base 27 in the locked state. The function of the EA plate 81 is invalidated according to the behavior of the occupant after the operation of the emergency lock mechanism 22, the presence / absence of the airbag operation, the physique (weight) of the occupant, and the like. And a cancel mechanism 82.

  On the other end side in the axial direction of the belt reel 12 (on the same side as the locking base 27), a cylindrical wall 83 having a stepped diameter is provided, and a substantially cylindrical outer frame case is formed inside the cylindrical wall 83. 84 is rotatably accommodated, and an inner ring 85 connected to the locking base 27 is disposed inside the outer frame case 84. The outer frame case 84 is connected to the cylindrical wall 83 of the belt reel 12 via a lock key 86 described later.

Between the outer frame case 84 and the inner ring 85, a band-shaped EA plate 81 formed in a spiral shape is disposed. The outer end of the EA plate 81 is fixed to the inner peripheral surface of the outer frame case 84, the inner end of the EA plate 81 is bent into a substantially U shape, and the end 81a is a portion of the locking projection 85a of the inner ring 85. It is fixed to. As shown in FIG. 12, the spiral direction of the EA plate 81 is substantially U-shaped when the outer frame case 84 receives a large torque and rotates in the pulling direction H with the locking base 27 locked. The EA plate 81 is set to be plastically deformed so that the position of the bent portion advances in the pulling direction H.
Therefore, in this embodiment, when the outer frame case 84 is connected to the belt reel 12 via the lock key 86, if the belt reel 12 tries to rotate in the webbing pull-out direction when the emergency lock mechanism 22 is activated, The energy absorbing action by the EA plate 81 works together with the twist of the bar 30.

FIG. 13 and FIG. 14 are diagrams showing a portion where the lock key 86 is installed.
As also shown in these drawings, an outward flange 87 is provided on the base side of the cylindrical wall 83 of the belt reel 12, and the axial direction of the belt reel 12 extends from the outward flange 87 to the cylindrical wall 83. A key groove 88 is formed. On the other hand, a similar key groove 89 corresponding to the key groove 88 on the belt reel 12 side is formed on the outer peripheral surface of the outer frame case 84. The lock key 86 is engaged with the key grooves 88 and 89 to lock the relative rotation of the belt reel 12 and the outer frame case 84 to each other.

  A resin stopper 90 that holds the lock key 86 in the locked position is attached to the cylindrical wall 83 of the belt reel 12. The stopper 90 has one end fixed to the vicinity of the front end of the cylindrical wall 83 and the other end fixed to the lock key 86. A thin connecting wall 90a is provided between the two fixed portions. When the lock key 90 is pressed with a large force in the axial direction, the connecting wall 90a is broken as shown in FIG. The lock key 86 is provided with a trigger piece 86a protruding outward from the outer peripheral surface of the cylindrical wall 83, and the trigger piece 86a is pressed from the outside.

  Further, as shown in FIGS. 10 to 12, an operation ring 91 for pressing the trigger piece 86 a of the lock key 86 is attached to the outer peripheral surface of the cylindrical wall 83 of the belt reel 12. As shown in FIG. 11, the operation ring 91 includes a drive ring 92 having an arm portion 92 a extending radially outward, and a driven ring 93 disposed adjacent to the drive ring 92. It is engaged by a concave portion 92b having a cam surface inclined in the direction and a convex portion 93b. However, when an external force in the rotational direction is applied to the drive ring 92, the concave portion 92b and the convex portion 93b slide on the cam surface, and the driven ring 93 is pressed and moved in the axial direction by the cam action at this time. The driven ring 93 is disposed adjacent to the trigger piece 86 a of the lock key 86 on the cylindrical wall 83, and the axial displacement of the drive ring 92 is restricted by the other side wall 14 b of the casing 14. Therefore, when an external force in the rotational direction is input to the drive ring 92 through the arm portion 92a, the driven ring 93 moves in the axial direction by the cam action, and at this time, the trigger piece 86a of the lock key 86 is pressed in the axial direction. Is done. As a result, the stopper 90 is broken, the coupling between the cylindrical wall 83 and the outer frame case 84 via the lock key 86 is released, and the function of the EA plate 81 is invalidated.

  A driving device 96 including a gas generator 94 and a piston 95 is disposed at a position facing the arm portion 92 a of the driving ring 92. The driving device 96 is controlled by a controller (not shown) according to the behavior of the occupant after the emergency lock mechanism 22 is activated, whether the airbag is activated, the physique of the occupant, and the like.

FIG. 15 is a graph showing three types of energy absorption characteristics (A), (B), and (C) when the emergency lock mechanism 22 of the seat belt device 101 of this embodiment is operated.
In the seat belt device 101, for example, when the airbag is activated when the emergency lock mechanism 22 is activated (when an activation signal is received from the SRS unit), the cancel mechanism 82 can be activated in an emergency. The torque absorbing function of the EA plate 81 can be disabled when the airbag is activated and the passenger behavior (movement stroke) is predicted to be relatively small. Therefore, in this case, either (A) or (B) of FIG. 15 is selected according to the pulling speed of the webbing 5. Further, when it is predicted that the occupant behavior (movement stroke) will increase without the airbag being activated in an emergency, the torque absorbing function of the EA plate 81 can be made effective. Therefore, in this case, either (A) or (C) in FIG. 15 is selected according to the webbing pull-out speed.
That is, in the seat belt device 101, an appropriate one of the three types of energy absorption characteristics can be selected according to the situation when the emergency lock mechanism 22 is operated.

  In addition, this invention is not limited to said embodiment, A various design change is possible in the range which does not deviate from the summary.

DESCRIPTION OF SYMBOLS 1,101 ... Seat belt apparatus 5 ... Webbing 10 ... Motor 12 ... Belt reel 20 ... Clutch 22 ... Emergency lock mechanism 30 ... Torsion bar (energy absorption means)
56A ... Large diameter gear (torque limiting means)
56B ... Small diameter gear (torque limiting means)
58 ... Spring plate (torque limiting means)
65 ... Absorption energy control means 81 ... EA plate (energy absorption means)

Claims (4)

A webbing that restrains an occupant seated in the seat;
A belt reel around which the webbing is wound;
An emergency lock mechanism for locking the rotation of the belt reel in the pull-out direction when the vehicle is in an emergency state;
An energy absorbing means that is interposed between the emergency lock mechanism and the belt reel and absorbs an excessive torque acting between the emergency lock mechanism and the belt reel when the emergency lock mechanism is activated;
In a seat belt device comprising:
A motor for applying a rotational driving force to the belt reel;
A clutch provided in a power transmission unit between the motor and the belt reel, and a clutch for connecting and disconnecting power transmission between the motor and the belt reel;
Torque limit that limits a torque between the motor and the belt reel by causing a part of the power transmission section to idle with a predetermined resistance when a torque exceeding a predetermined value acts between the motor and the belt reel. Means,
By controlling on / off of the clutch according to the behavior of the occupant after the operation of the emergency lock mechanism or the predicted behavior, an additional energy absorption function by the torque limiting means when the emergency lock mechanism is operated And an absorbed energy control means for controlling the presence or absence of the seat belt device.   2. The seat belt device according to claim 1, wherein the absorbed energy control means turns on the clutch when the webbing pull-out speed immediately after the operation of the emergency lock mechanism is larger than a threshold speed.   The seat belt device according to claim 2, wherein the threshold speed is adjusted so as to decrease as the absolute value of the acceleration acting on the vehicle in an emergency increases.   The seatbelt device according to any one of claims 1 to 3, wherein the absorbed energy control means turns on the clutch when the airbag is not deployed in an emergency.

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