JPH0234119Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an inertia plate for an inertia lock mechanism that is most suitable for a webbing retractor for a seat belt device mounted on an automobile.

[Prior art]

2. Description of the Related Art In a seat belt device installed in an automobile, a webbing for restraining an occupant is wound onto a winding device using a biasing force so that the webbing is tightly attached to the occupant. In addition, this webbing take-up device
In the event of a vehicle emergency, the inertia lock mechanism is activated to stop the rapid rotation of the webbing and protect the occupant by restraining the webbing.

The inertia plate used in this inertia lock mechanism requires a predetermined inertia mass, and the error in this mass is strictly limited. Further, this inertia plate needs to be provided with a shaft support portion for the webbing take-up shaft, a spring bearing portion provided between the webbing take-up shaft, a guide portion for the lock plate, etc., and requires high dimensional accuracy. For this reason, inertia plates have conventionally been formed by precision processing such as die casting and forging.

[Purpose of invention]

The object of the present invention is to obtain an inertia plate for an inertia lock mechanism that does not require precision machining of the inertia mass portion and can maintain mass accuracy at a predetermined value.

[Summary of the idea]

In the inertia plate for an inertia lock mechanism according to the present invention, the inertia mass and the case are separated, the case is made of synthetic resin, and the metal plate serving as the inertia mass is accommodated in the case. Furthermore, a plurality of receiving recesses are formed at asymmetric positions around the axis of the metal plate, and a plurality of pins are provided from the metal plate to each of these receiving recesses to prevent rotation of the metal plate. The plates are assembled in a uniform manner, and one set of pins and receiving recesses is dimensioned to tightly fit to prevent minute rotation of the metal plate.

[Example of idea]

FIG. 1 shows an exploded perspective view of a webbing retractor to which an inertia plate 10 according to the present embodiment is applied.

This webbing retractor is mounted on a vehicle by fixing the frame 12 to a vehicle body (not shown). Leg plates 14 and 16 projecting parallel to each other from both sides of the frame 12 have a winding shaft 1
8 is pivoted. One end of an occupant restraining webbing (not shown) is attached to this winding shaft 18, so that the middle portion of the webbing is wound up in a layered manner. The occupant can attach the webbing by engaging a tongue plate attached to the other end of the webbing to a buckle device attached to the vehicle body.

At the end of the winding shaft 18 protruding from the leg plate 14, there is a small diameter shaft portion 20 and a rectangular shaft portion 22 projecting in the radial direction.
is formed. A pair of substantially C-shaped lock plates 24 facing each other are attached to the rectangular shaft portion 22 so as to rotate together with the winding shaft 18. These lock plates 24 are able to rotate slightly relative to the rectangular shaft portion 22, and when they are moved in opposite directions (direction of arrow A),
The rotation is stopped by meshing with an internally toothed ratchet foil 26 fixed to the outside of the leg plate 14, thereby stopping the webbing drawing rotation of the take-up shaft 18.

The inertia plate 10 has a synthetic resin case 28 and a metal plate 30. As shown in FIGS. 2 and 3, the synthetic resin case 28 has a bearing ring 32 having a hollow hole formed in the center thereof, and the small diameter shaft portion 20 of the winding shaft 18 is inserted into this bearing ring 32. It is becoming more and more common. Thereby, the inertia plate 10 is coaxially rotatable relative to the winding shaft 18.

Since the case 28 is made of synthetic resin, precision machining is possible, and a guide elongated hole 38 for guiding a pin 36 protruding from the lock plate 24 is formed in a side plate 34 that protrudes radially from the bearing ring 32. There is. Further, a protection ring 40 is provided coaxially with the bearing ring 32, and a coil portion of a torsion coil spring 42 is accommodated between the protection ring 40 and the bearing ring 32. This torsion coil spring 42 has one straight portion 42A connected to the case 2.
8, another straight portion 42B is brought into contact with a holder 44, and this holder 44 is fitted onto the small diameter shaft portion of the winding shaft at a predetermined relative rotation angle. As a result, the inertia plate 10 is urged against the take-up shaft 18 in a direction that follows the webbing drawer rotation direction (direction of arrow B) of the take-up shaft 18. Due to this biasing force, the inertia plate 10 biases the lock plate 24 in the direction opposite to the direction of arrow A through its guide elongated hole 38.
Lock plate 24 with internal tooth ratchet foil 26
It is kept separate from the However, when the inertia plate 10 lags in rotation with respect to the winding shaft 18, the guide elongated hole 38 moves the lock plate 24 in the direction of arrow A.

A peripheral wall 46 protrudes from the outer peripheral tip of the side plate 34 of the synthetic resin case 28, so that the peripheral wall 46 and the side plate 34 have a substantially U-shape, and the metal plate 30 is housed inside. ing. Peripheral wall 46
A claw 48 protrudes toward the inner periphery at the tip thereof, and engages with the end surface of the metal plate 38 housed in the case 28 to prevent the metal plate 30 from falling off.

The metal plate 30 is manufactured by stamping by press working, and has a ring shape with a through hole 50 in the axial center. Three circular arc grooves 52, facing this through hole 50 and expanding the inner diameter of the through hole 50,
54, 56 are formed, and pins 58, 60, 62 protruding from the case side plate 34 are inserted into these arcuate grooves, respectively. This prevents the metal plate 30 from rotating relative to the case 28.

Further, these arcuate grooves 52, 54, and 56 are arranged at asymmetric positions around the axis. For this reason, the metal plate 30 is installed in a uniform position to prevent assembly errors.

Furthermore, among the combinations of arcuate grooves and pins, the combination of the arcuate groove 54 and the pin 60 is either tightly loosely fitted or slightly press-fitted, so that the metal plate 30 and the case 28 are aligned with their axes. It is designed so that there is no slight relative rotation around it. However, the combinations of the arcuate groove 52 and the pin 58 and the arcuate groove 56 and the pin 62 are not tightly assembled and have a large gap, making it easy to assemble the metal plate 30.

In the webbing retractor configured as described above, since the metal plate 30 of the inertia plate 10 has a simple ring shape, it is easy to process, and even though it is manufactured by non-precision processing such as press molding, it is easy to set. The mass can be maintained with high precision, and the winding shaft 18
can be assembled accurately. Therefore, the rotational delay from the winding shaft is caused in the inertia plate 10 at a desired rotational acceleration of the winding shaft, and the lock plate 24 is engaged with the internally toothed ratchet wheel 26 to rotate the winding shaft 1.
Rotation of the webbing drawer 8 can be prevented.

If a ratchet wheel 64 is carved on the outer periphery of the case peripheral wall 46 so that it can be engaged with an acceleration sensor that detects the acceleration of the vehicle body, an even more precise inertial lock mechanism can be constructed.

FIG. 4 shows a metal plate 66 used in a second embodiment of the present invention. This metal plate 66 is formed thinner than the metal plate 30 of the previous embodiment. This reduces the inertial mass,
It is designed to be used in an inertia lock mechanism that stops pulling out the webbing in response to a large pull-out acceleration of the webbing take-up shaft.

This metal plate 66 has a spacer 68 from one end in the axial direction.
protrudes, and the total dimension of the axial length of this spacer 68 and the wall thickness of the metal plate 66 is the same as the wall thickness of the metal plate 30 of the above embodiment, thereby making this metal plate 66 It can be easily assembled into a synthetic resin case 28 similar to the embodiment. Since the inertial mass and the case are thus separated, it is possible to obtain an inertia lock mechanism that stops the webbing drawer in response to a desired set drawer acceleration.

[Effect of idea]

As explained above, in the present invention, the inertia plate is separated into a synthetic resin case and a metal plate, the rotation of the metal plate is stopped by the receiving recess and the pin, and the receiving recesses are formed at symmetrical positions around the axis. As a result, the assembly can be made uniform, and one set of the pin and the receiving recess is tightly fitted, so that minute rotation of the metal plate can be prevented.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view showing a webbing retractor to which a first embodiment of the inertia plate for an inertia lock mechanism according to the present invention is applied, Fig. 2 is a front view of the inertia plate, and Fig. 3 is Fig. 2- FIG. 4 is an exploded cross-sectional view of the inertia plate along a line, and FIG. 4 is a side view of the metal plate used in the second embodiment. 10...Inertia plate, 28...Synthetic resin case,
30, 66...Metal plate, 50...Through hole, 52,
54, 56...Circular groove, 58, 60, 62...Pin.

Claims (1)

[Claims for Utility Model Registration] (1) A synthetic resin case, a metal plate inserted into the case, a plurality of receiving recesses formed at asymmetric positions around the axis of the metal plate, and a metal plate inserted into the case; a plurality of pins that protrude and are respectively inserted into the receiving recesses to prevent rotation of the metal plate; one set of the combinations of the plurality of pins and the receiving recesses is tightly fitted to prevent minute rotation of the metal plate within the case; An inertia plate for an inertia lock mechanism characterized by blocking. (2) The above-mentioned utility model registration characterized in that the metal plate is ring-shaped with a through hole in the shaft core, and the receiving recess is a groove bored to enlarge the inner diameter of the through hole. An inertia plate for an inertia lock mechanism according to claim (1).