KR20030021256A - Energy absorbing seat belt retractor - Google Patents

Abstract

The seat belt retractor 50 has a spool 56 around which the seat belt is wound. The locking mechanism 60 locks the spool against rotation at least initially. First force-limiting mechanism 58, such as torsion bar 58, allows the spool to rotate in a controlled manner after locking the spool. The second force-limiting mechanism is located in the recess 100 of the spool and includes a portion of the spool and an adjoining portion of the locking mechanism for increasing the restraining force on the seat belt before the first force-limiting mechanism 58 acts. . Torsion bar 58 is connected to the spool at one end and to the locking mechanism at the other end. The second locking mechanism has a recess, a keyway or slot 102, and a protrusion 104 formed on one of the interlocking portions of the bore and the locking mechanism.

Description

Seat belt shrinkage {ENERGY ABSORBING SEAT BELT RETRACTOR}

The seat belt systolic with energy absorbing mechanisms allows the seat belt to be controllably stretched from the systolic spool as the mechanism in the systolic spool produces some determinable or constant contraction force or torque to inhibit elongation. This operation allows the vehicle occupant to move forward during the collision, thus alleviating the impact force on the vehicle occupant. US 6,105,894 proposes the use of additional energy absorbing elements such as shear pins, which extend from the end face of the spool flange to connect the spool to the locking mechanism. These pins must first be sheared to allow the torsion bar to operate. The physical characteristics of the shear pins increase the force or torque exerted on the vehicle occupant, leading to the peak of the force curve corresponding to the force or energy required to break or shear the shear pins. After the pin is sheared, the torsion bar can be twisted to produce a more constant value of contraction force, specified by the characteristics of the particular torsion bar or other type of energy absorbing mechanism used.

One of the drawbacks of this prior art systolic is that the shear pin acts as a rivet to secure the instrument to the spool, and if such rivet or shear pin breaks, the systolic loses its function. In addition, in conventional designs, a piece of sheared or broken pin may be caught in a location in the systolic that will jam the systolic.

Summary of the Invention

The seat belt retractor according to the invention comprises a spool wound around the seat belt, a locking mechanism that locks the spool at least initially against rotation, and a torsion bar for allowing the spool to rotate in a controlled manner after the spool is locked. A second force-limiting mechanism comprising a first first force-limiting mechanism and an adjacent portion of the locking mechanism positioned in the recess of the spool and for increasing the restraining force on the seat belt before the spool and the first force-limiting mechanism act. It includes a restriction mechanism. The torsion bar is at least partially located in the spool bore and is connected to the spool at one end and to the locking mechanism at the other end. The second locking mechanism has a recess, a keyway or slot, a protrusion, a breakable tab formed on one of the spool bores, and an interlocking portion of the locking mechanism.

The present invention relates to a seat belt retractor, and more particularly to a seat belt retractor having an energy absorbing mechanism.

1 is a cross-sectional view showing the main components of a seat belt shrinker embodying the present invention;

2A is a front view of the locking mechanism part;

2B is a side view of the locking mechanism portion;

2C is a cross-sectional view showing a modification of the present invention in which the arrangement of slots and pins is reversed;

3a is a sectional view of the spool,

3b is a front view of the spool,

3c is a side view of the spool,

4 is a perspective assembled view of the spool and locking mechanism (lock wheel not shown),

5 shows various force / time (deflection) curves.

1-4 illustrate the main components of a seat belt retractor embodying the present invention. The seat belt retractor 50 includes a “U” shaped frame 52 and a locking subassembly 54 having openings 52a and 52b to support the spool. These openings act as bearings. The spool and locking subassembly includes spool 56, torsion bar 58 and locking mechanism 60. One end 62 of the torsion bar 58 has a plurality of splines 64 that are drive coupled with a plurality of mating splines 66 formed (in a known manner) on the torsion bar. The extension 68 of the torsion bar 58 is received into a spring arbor 70 and biased by a rewind spring 72. The other end 74 of the recoil portion of the torsion bar 58 is fixed to the locking wheel mechanism 60. The mechanism 60 has a splined bore 80, which receives a spline 82 formed on the end 74 of the torsion bar. This rotatably connects the torsion bar and the locking mechanism. The locking mechanism and the torsion bar are fixed axially by swaging these parts together. The torsion bar 68 also has an additional extension 84, which rotates with the spool prior to actuation of the torsion bar and serves as a web sensor 86 of known type which is schematically indicated. The lock mechanism 60 has a ratchet wheel 86 forming a cavity 88. Various components of the web sensor, such as web sensor pawls, are located in cavities 88 (also shown in FIG. 4) formed by ratchet wheels. A locking wheel 92 having a plurality of teeth 94 is fixed to the main body 90 of the locking mechanism. The locking pawl 96, shown schematically, is rotatably mounted to the frame and engages one or more teeth 94 of the lower wheel in a known manner in the operation of the web sensor or vehicle sensor 98. As is known in the art, many seat belt constrictors have locking rings (not shown) that are rotatable about the shaft of the constrictor (in this case, the torsion bar), and the operation of the web sensor or cooperating vehicle sensor is such locking. Connect the ring to the systolic shaft. This operation allows the locking ring to rotate a small amount to engage the locking pawl with the locking wheel. The web sensor has an inertial disc loosely mounted to the extension 84 and a web sensor pole (not shown) rotatably mounted to the pin 87 of the ratchet wheel 86, which seats from the systolic spool. In response to rapid elongation of the belt, it moves and engages closely spaced teeth on the lock ring, thereby coupling the lock ring to the pawl and systolic shaft. The vehicle sensor 98, which may be supported by the locking ring, also includes a sensor pole 98a that is moved to the operating position by a movable mass (not shown) when the vehicle is rapidly decelerated. In the operating position the vehicle sensor pawl 98a engages the teeth 86a of the ratchet wheel 86, thereby coupling the locking ring to the systolic shaft.

4 shows that the central bore 100 of the spool 56 has at least one slot (also called a keyway) 102. The body 90 of the instrument 60 has a number of protrusions 104 received in the keyway 102. The protrusion 104 and the keyway 102 drive connect the outside of the spool to the outside of the body 90 of the instrument 60. The main body 90 has a small diameter portion 90a accommodated in the bore 100 of the spool, and an opening 52b in the frame, that is, a large diameter portion 90b accommodated and fixed in the bearing.

In the embodiment shown, the spool also has two bores 110 perpendicular to the bore 100. With the torsion bar 58 positioned as shown in FIG. 2, the tool is positioned in the bore 110, and the spline 66 of the spool 64 is deformed locally by applying force to the spline 64 of the torsion bar. ) And the driving contact state. Other means may be used to secure the torsion bar to the spool.

The spool 56 also has a provision to receive the end of the seat belt 130. Such provision has a known slot 132 in which the end of the belt 130 is received. The retaining portion can be strengthened by first fixing the end of the belt around the pin that fits in the slot 132. The belt is wound around the spool body 134 and is held between optional flanges 136a and 136b.

During a collision the vehicle and / or web sensor connects a locking ring (not shown) to the shaft (torsion bar) to allow the locking ring to rotate a small amount. A portion of the lock ring is operably connected to the lock pawl 96, wherein rotation of the lock ring moves the lock pawl 96 to engage the teeth 94 of the lock wheel 92, thereby at least initially. This prevents the seat belt webbing from extending from the spool 92. As the collision progresses, a collision force is transmitted to the seat belt by the vehicle occupant, which tends to pull the seat belt from the spool 56 in the direction of arrow F (see FIG. 1). This force is resisted not only by the interaction of the locking pawl and the locking tooth 94, but also by the interaction between the protrusion 102 and the slot 104. As the level of the collision force increases to a level sufficient to shear the protrusion 102 from the body 90a of the locking mechanism 60, a reaction force such as the reaction force magnitude 202 is generated as shown in FIG. Because of the higher reaction force indicated by reference numeral 202a in FIG. 5 generated by the slots and pins, the forward movement of the vehicle occupant is strongly impeded and the movement of the vehicle occupant is constrained. When the protrusions 104 are sheared, they are caught in corresponding keyways, and the spool and torsion bar are free to rotate relative to the locking mechanism since the continuous force generated by the vehicle occupant is input to the seat belt and then the spool. As can be appreciated, when the end 74 is held fixed to the non-rotating locking mechanism 60 held by the locking pawl, the end 62 of the torsion bar begins to twist. As the torsion bar rotates, it will generate less reaction force 202a, as shown in FIG. 5, which will prevent the vehicle occupant from moving forward, but this level of force will cause the torsion bar. This allows the vehicle occupant to move forward so that the impact forces acting on the vehicle occupant are limited. As can be appreciated, one advantage of this type of design is that the sheared protrusion 104 is embedded in the spool. It does not interfere with the functionality of the spool.

The trace in FIG. 5 represents experimental data, in particular a function of belt force and time (an example of belt extension). Trace 200 shows comparative experimental data for a similar seat belt retractor without slots and pins.

Figure 2c shows one embodiment in which a slot is formed in the locking mechanism and the shear pin is incorporated in the spool.

Claims (4)

In the seat belt constrictor 50, A spool 56 with a seat belt wound around it, A locking mechanism 60 that locks the spool against rotation at least initially, A first force-limiting mechanism 58 for allowing the spool to rotate in a controlled manner after locking the spool, A second force-limiting mechanism, located in the recess 100 of the spool, comprising a portion of the spool and a proximal portion of the locking mechanism for increasing the restraining force on the seat belt before the first force-limiting mechanism 58 acts. Containing Seat belt systolic. The method of claim 1, The recess of the spool 56 has a portion of the bore, and the second force-limiting mechanism is a slot or keyway 102 formed on one of the interlocking portions of the bore and locking mechanism 60, and the protrusion 104. With Seat belt systolic. The method of claim 2, The first force-limiting mechanism 58 is a torsion bar with one end connected to the spool 56 and the other end connected to the locking mechanism 60. Seat belt systolic. The method of claim 1, The second force-limiting mechanism includes an opposing slot 102 and a breakable protrusion 104. Seat belt systolic.