JP2004504201A - Energy absorption type seat belt retractor - Google Patents

Abstract

The seat belt winding device (50) has a spool (56) around which the seat belt is wound. The lock mechanism (60) locks the spool so as not to rotate at least at the initial stage. For example, a first force limiting mechanism such as a torsion bar (58) controls and rotates the spool after locking the spool. The second force limiting mechanism is located within the recess (100) of the spool and is adapted to increase the restraining force acting on the seat belt before the first force limiting mechanism takes effect, and a portion of the spool and the locking mechanism. It has an adjacent portion. One end of the torsion bar (58) is connected to the spool, and the other end is connected to the lock mechanism. The second force limiting mechanism has a recess, a keyway or slot (102), and a protrusion (104) formed in one of the spool bore and the interlocking portion of the locking mechanism.

Description

[0001]
The present invention relates generally to seat belt retractors, and more particularly to seat belt retractors having an energy absorbing mechanism.
[0002]
A seat belt retractor having an energy absorbing mechanism can control the seat belt from the take-up spool because a mechanism in the spool generates a certain level or a constant reaction force or torque because the mechanism in the spool prevents stretching. Can be stretched. This action allows the occupant of the vehicle to move forward during the collision, reducing the collision force applied to the occupant. U.S. Pat. No. 6,105,894 suggests the use of additional energy absorbing elements, such as shear pins, extending from the end face of the spool flange and connecting the spool to a locking mechanism. These pins must first be sheared for the torsion bar to work. Depending on the physical properties of the shear pin, the force or torque applied to the occupant increases and peaks in the force curve corresponding to the force or energy required to break or shear the shear pin. After the pin is sheared, the torsion bar is allowed to twist, producing a more constant value of reaction force, determined by the properties of the particular torsion bar or other kind of energy absorbing mechanism used .
[0003]
One of the disadvantages of this prior art winder is that the shear pin acts as a rivet to hold the locking mechanism to the spool, and once the rivet or shear pin breaks, the winder loses its functionality. To lose. Further, in conventional designs, the sheared or broken pieces of the pins themselves can become lodged in locations within the winder, causing the winder to become immobile.
[0004]
The seat belt retractor of the present invention includes a spool around which a seat belt is wound, a lock mechanism that locks the spool so as not to rotate at least initially, and a mechanism that controls rotation of the spool in a controlled manner after locking the spool. A first force limiting mechanism, such as a torsion bar, for enabling a spool located in the recess of the spool to increase the binding force acting on the seat belt before the first force limiting mechanism takes effect; And a second force limiting mechanism having a portion adjacent to the locking mechanism. At least a part of the torsion bar is located in the hole of the spool, one end is connected to the spool, and the other end is connected to the lock mechanism. The second force limiting mechanism has a recess, a keyway or slot, and a protrusion formed in one of the spool bore and the interlocking portion of the locking mechanism.
[0005]
DETAILED DESCRIPTION OF THE INVENTION FIGS. 1-4 show the main elements of a seat belt retractor incorporating the present invention. The seat belt retractor 50 includes a U-shaped frame 52 having openings 52a, 52b for supporting a spool and locking subassembly 54. These openings serve as bearings. The spool and locking subassembly includes a spool 56, a torsion bar 58 and a locking mechanism 60. One end 62 of the torsion bar 58 includes a plurality of splines 64 that mesh (in a known manner) to transmit power to a plurality of mating splines 66 formed on the torsion bar. The torsion bar extension 68 is received in a spring arbor 70 and is biased by a rewind spring 72. The other end 74, which is the reaction end of the torsion bar 58, is fixed to the wheel lock mechanism 60. The wheel lock mechanism 60 has a keyed hole 80 for receiving a spline 82 formed in the end 74 of the torsion bar. This mechanism couples the torsion bar and the lock mechanism 60 to rotate. The lock mechanism and the torsion bar are fixed in the axial direction by swaging these components together. The torsion bar 68 further has an additional extension 84 that rotates with the spool prior to actuation of the torsion bar and serves as part of a known type web sensor 86, shown schematically. The locking mechanism 60 has a ratchet wheel 86 defining a cavity 88. Various components of the web sensor, such as the web sensing pawl, are located inside a cavity 88 (also shown in FIG. 4) formed by the ratchet wheel. A lock wheel 92 having a plurality of teeth 94 is fixed to the main body 90 of the lock mechanism. A locking claw 96, shown schematically, is rotatably mounted on the frame and engages one or more teeth 94 of the locking wheel when the web sensor or vehicle sensor 98 operates in a known manner. As is known in the prior art, many seat belt retractors include a lock ring (not shown) that is rotatable relative to the retractor shaft (in this case, a torsion bar). The locking ring is coupled to the winder shaft by actuation of a web sensor or a cooperating vehicle sensor. By this operation, the lock ring is slightly rotated, and the lock pawl is moved by this operation to engage with the lock wheel. The web sensor has an inertial disc loosely attached to the extension 84 and a web sensor pawl (not shown) rotatably attached to a pin 87 of a ratchet wheel 86. In response to a sudden stretching of the seat belt from the spool of the lock belt, the lock ring is moved to mesh with teeth formed at close intervals, thereby coupling the lock ring to the pawl, and the shaft of the winding device. To join. The vehicle sensor 98, which can be supported by a lock ring, also has a vehicle sensor claw 98a that moves to an operative position by a movable mass (not shown) when the vehicle undergoes a sudden deceleration. In the actuated position, the vehicle sensor pawl 98a engages the teeth 86a of the ratchet wheel 86, thereby coupling the lock ring to the winder shaft.
[0006]
FIG. 4 shows that the center hole 100 of the spool 56 has at least one slot (also referred to as a keyway) 102. The body 90 of the locking mechanism 60 has a plurality of protrusions 104 that are received in the keyways 102. The protrusion 104 and the key groove 102 couple the inside of the spool to the outside of the main body 90 of the lock mechanism 60 so as to transmit power. The main body 90 has a small-diameter portion 90a received in the hole 100 of the spool and a large-diameter portion 90b received and held in an opening 52b provided in the frame, that is, a bearing.
[0007]
In the embodiment shown, the spool also has two holes 110 perpendicular to the holes 100. With the torsion bar 58 in the position shown in FIG. 2, a tool is placed in the hole 110 and a force is applied to maintain the spline 66 of the spool in contact with the torsion bar spline 64 to transmit power. So that the spool is locally deformed. Other means can be used to secure the torsion bar to the spool.
[0008]
The spool 56 further includes a structure for receiving an end of the seat belt 130. The structure includes a known slot 132 in which the end of the belt 130 is received. Retention can be increased by first securing the end of the belt around a pin that fits into slot 132. The belt is wound around spool body 134 and held between optional flanges 136a, 136b.
[0009]
In the event of a collision, the vehicle and / or web sensor couples a lock ring (not shown) to a shaft (torsion bar), which causes the lock ring to rotate slightly. A portion of the lock ring is operably coupled to the lock pawl 96 such that rotation of the lock ring moves the lock pawl 96 into engagement with the teeth 94 of the lock wheel 92, thereby at least initially providing the seat belt webbing. Stretching from the spool 56 is prevented. As the collision process progresses, the collision force acts on the seatbelt via the occupant of the vehicle and attempts to pull the seatbelt away from the spool 56 in the direction of arrow F (see FIG. 1). This force is resisted by the interaction between the locking pawl and the locking teeth 94 as well as the interaction between the projection 104 and the slot 102. When the level of the impact force increases to a level sufficient to cause the protrusion 104 to shear from the body 90a of the locking mechanism 60, a reaction force is generated, such as a reaction force of magnitude 202 shown in FIG. The high reaction force generated by the slots and pins, indicated by the numeral 202a in FIG. 5, forces the forward movement of the occupant to be impeded and limits the occupant's movement. When the protrusions 104 break, they remain in the corresponding keyways, and the spool and torsion bar engage the locking mechanism as long as the continuous force created by the occupant is applied to the seat belt and then to the spool. Rotate freely against. It can be seen that it is the torsion bar end 62 that begins to twist when the torsion bar end 74 is fixedly held by the non-rotating locking mechanism 60 held by the locking pawl. . Rotation of the torsion bar will produce a smaller reaction force 202a, also as shown in FIG. The reaction resists the occupant's forward motion, but the level of this force is such that the occupant moves forward so that the impact force acting on the occupant is limited, in this case based on the characteristics of the torsion bar. Will exercise. It can be seen that one of the advantages of this type of construction is that the folded projections 104 will not become wrapped within the spool and will interfere with the functionality of the spool.
[0010]
The trajectory in FIG. 1 shows the test data, in particular the belt force, as a function of time (representing belt stretching). Trajectory 200 is comparative test data for a similar seat belt retractor without slots and pins.
[0011]
FIG. 2c shows an example where a slot is formed in the locking mechanism and a shear pin is incorporated into the spool.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing main elements of a seat belt retractor incorporating the present invention.
FIG. 2a is a partial end view of the locking mechanism.
FIG. 2b is a partial side view of the lock mechanism.
FIG. 2c is a cross-sectional view illustrating another embodiment of the present invention in which the arrangement of slots and pins is reversed.
FIG. 3a is a sectional view of a spool.
FIG. 3b is an end view of the spool.
FIG. 3c is a side view of the spool.
FIG. 4 is an assembly view showing an isometric view of a spool and a lock mechanism (a lock wheel is not shown).
FIG. 5 shows various force / time (deflection) curves.

Claims (4)

A spool (56) around which a seat belt is wound,
A lock mechanism (60) for locking the spool so as not to rotate at least at the initial stage, and a first force limiting mechanism (58) for controlling and rotating the spool after locking the spool;
A portion of the spool and the locking mechanism, located within the recess (100) of the spool, for increasing the binding force acting on the seat belt before the first force limiting mechanism (58) takes effect. A seat belt retractor having a second force limiting mechanism having an adjacent portion. The recess of the spool (56) includes a hole portion, and the second force limiting mechanism includes a slot or key formed in one of the hole and the interlocking portion of the locking mechanism (60). The seat belt retractor (50) of any preceding claim, having a groove (102) and a protrusion (104). The seat belt winding according to claim 2, wherein the first force limiting mechanism (58) is a torsion bar having one end connected to the spool (56) and the other end connected to the locking mechanism (60). Taking device (50). The seat belt retractor (50) of claim 1, wherein the second force limiting mechanism has opposing slots (102) and breakable protrusions (104).