JPH037233Y2 - - 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.

Here, the inertia plate of the inertia lock mechanism must have a predetermined inertia mass. For this reason, the inertia plate is generally made of metal. On the other hand, the inertia plate includes a pivot portion for the webbing take-up shaft, a ratchet foil carved on the outer peripheral surface of the inertia plate that engages with the pawl of an acceleration sensor that is activated in a vehicle emergency, and a link between the pivot portion and the ratchet foil. It is necessary to provide a spring receiving part and a guide part for the lock plate, which are provided on the side surface between the parts, and high dimensional accuracy is required for both of these parts. Therefore, in order to form the inertia plate, a die-gas casting method is generally used to integrally mold the metal material.

However, the Tygust casting method involves precision processing, and when it is used, a die-casting machine must be used and a die-casting mold is required, making the molding process more difficult and costly than press molding or the like. In addition, if the inertia plate is manufactured by integrally molding a metal material using the die-casting method, there will be some changes in cross section, such as the above-mentioned shaft support part and guide part, so it is necessary to set the dimensions to obtain the set inertia mass. etc. become complicated, and since all parts of the inertia plate (including the parts where the cross section changes) contribute to the inertia mass, there is a problem that dimensional accuracy becomes strict.

In consideration of the above facts, the object of the present invention is to obtain an inertia plate for an inertia lock mechanism that is easy to mold and can easily obtain a set inertia mass.

[Summary of the idea]

In order to achieve such an object, the inertia plate for an inertia lock mechanism according to the present invention has a disc shape and is provided with a bearing part having a shaft support hole for pivotally supporting a webbing take-up shaft in the shaft core part, and a bearing part in the outer peripheral part. A case made of synthetic resin is provided with a ratchet foil for stopping the rotation of the webbing drawer in cooperation with an acceleration sensor activated in the event of a vehicle emergency, and a case is held between the bearing portion of the synthetic resin case and the ratchet foil. and a ring-shaped metal plate having an inner diameter larger than the outer diameter of the bearing portion and a substantially uniform cross section, which imparts an inertial mass to the synthetic resin case.

According to the above configuration, the webbing take-up shaft is inserted into the support hole of the bearing of the synthetic resin case, and the webbing take-up shaft is supported by the bearing. Furthermore, a ratchet wheel is provided on the outer periphery of the case made of synthetic resin to stop the rotation of the webbing drawer in cooperation with an acceleration sensor that is activated in the event of a vehicle emergency. Both the bearing portion and the ratchet wheel require high dimensional accuracy, but since the case is made of synthetic resin, it can be easily precisely machined.

A metal plate is held between the bearing portion of the case and the ratchet wheel. Here, the metal plate is assumed to be ring-shaped, but this metal plate only needs to secure inertial mass, and in other words, precision machining to ensure high dimensional accuracy is not forced, so press It can be molded by molding, etc., and is easy to mold. In addition, the metal plate
Since the cross section is substantially uniform, the set inertial mass can be easily applied to the case.

Furthermore, since the metal plate has a ring shape with an inner diameter larger than the outer diameter of the bearing part, the spring bearing part and the guide part of the lock plate mentioned above are formed between the bearing part and the hole in the metal plate. It can be installed in a predetermined space.

In this way, the functions required of an inertia plate for an inertia lock mechanism, namely, forming parts such as bearings with high dimensional accuracy and securing inertia mass, can be achieved.
By dividing the inertia plate into a synthetic resin case and a ring-shaped metal plate with a substantially uniform cross section, and by assigning the former function to the synthetic resin case and the latter function to the metal plate, molding is possible. This makes it easy to obtain the set inertial mass.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[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 intermediate 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 can be rotated slightly relative to the rectangular shaft portion 22, and when they are moved in opposite directions (in the 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. As a result, 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. A protection ring 40 is provided coaxially with the bearing ring 32, and a coil portion of a torsion coil spring 42 is housed between the protection ring 40 and the bearing ring 32. This torsion coil spring 42 has one straight portion 42A attached to the synthetic resin case 28, and the other straight portion 42B attached to the holder 44.
The holder 44 is fitted onto the small diameter shaft portion 20 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 arrow A direction through its guide elongated hole 38, and holds the lock plate 24 apart from the internally toothed ratchet wheel 26. There is. However, when the inertia plate 10 lags behind the rotation of the winding shaft 18, the guide elongated hole 38 is inserted into the lock plate 24.
is moved 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 circumference from the tip of the case 28 and engages with the end surface of the metal plate 30 housed in the case 28 to prevent the metal plate 30 from falling off.

The metal plate 30 is manufactured by stamping using press processing, and has a ring shape with a uniform cross section and a through hole 50 in the axial center. Three arcuate grooves 52, 54, and 56 are formed facing this through hole 50 and widening the inner diameter of the through hole 50, and the side plate 3
Pins 58, 60, 62 protruding from 4 are inserted into these arcuate grooves 52, 54, 56, 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.

Further, arcuate grooves 52, 54, 56 and pins 58, 6
Among the combinations with 0 and 62, 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 around the axis. It is designed to prevent slight relative rotation. 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 this way, in this embodiment, the synthetic resin case 2
8, a bearing ring 32, a protection ring 40, a long hole 38 into which the pin 36 of the lock plate 24, etc., which require high precision are inserted, are provided by resin molding.
The inertial mass is possessed by the metal plate 30, and this metal plate 3
Since the ring 0 has a simple ring shape and can be formed by press molding or the like, the inertia plate 10 can be easily formed. Moreover, cost reduction can be achieved. Furthermore, the set inertial mass can be easily imparted to the synthetic resin case 28 by making the metal plate 30 ring-shaped and having a uniform cross-sectional shape.

In FIG. 4, a ring-shaped metal plate 30 is attached to the case 6 in advance.
This example shows an example where the file is buried in 6. This type of buried structure can easily be molded in one piece using today's insert molding technology. The other parts are completely the same as the previous embodiment. With such a structure, not only can the process of assembling the metal plate 30 be omitted, but also
There is also no possibility that the metal plate 30 will move within the case when the webbing retractor is operated.

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, The set 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 vehicle body acceleration, an even more precise inertial lock mechanism can be constructed.

[Effect of idea]

As explained above, according to the present invention, the inertia plate for the inertia lock mechanism consists of a synthetic resin case provided with a bearing portion and a ratchet foil, and a ring-shaped metal plate held in the synthetic resin case with approximately the same cross section. Since it has a spring bearing part,
Places that require high dimensional accuracy, such as the guide portion of the lock plate, can be satisfied by molding the case with resin, and metal plates with inertial mass can be molded using non-precision processing such as press molding. This has the excellent effect of facilitating the molding of an inertia plate for an inertia lock mechanism.

In addition, since the metal plate of the present invention has a simple ring shape and a substantially identical cross-sectional shape, the set inertial mass can be easily applied to the synthetic resin case through the metal plate, which is an excellent effect. has.

[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 a longitudinal sectional view of another embodiment of the inertia plate. 10...Inertia plate, 18...Webbing take-up shaft,
24... Lock plate, 28, 66... Synthetic resin case, 30... Ring-shaped metal plate, 32...
Bearing ring, 38...Long hole, 40...Protection ring, 50...Thickness dimension of metal plate, t...Thickness dimension of inertia plate.

Claims (1)

[Scope of utility model registration request] A bearing part that has a disc shape and has a shaft support hole for pivotally supporting a webbing take-up shaft is provided in the shaft core part, and works in conjunction with an acceleration sensor on the outer periphery that is activated in the event of a vehicle emergency to stop the rotation of the webbing drawer. A case made of synthetic resin is provided with a ratchet foil for the purpose of the bearing, and a case made of synthetic resin is held between the bearing portion of the case made of synthetic resin and the ratchet foil, and has an inner diameter larger than the outside diameter of the bearing portion and has a substantially uniform cross section. An inertia plate for an inertia lock mechanism, comprising: a ring-shaped metal plate that imparts inertia mass to the synthetic resin case.