JPH10250529A - Energy absorbing mechanism for seat belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an energy absorbing mechanism for seat belt with a low manufacturing cost, as well as to allow to regulate the energy absorbing load corresponding to the vehicle characteristic. SOLUTION: A retractor 100 for seat belt has an energy absorbing mechanism 200 furnishing a bobbin 3 winding a webbing; a retractor base 1 rotatable relatively to the bobbin 3; and a torsion bar 2 combined integrally to the bobbin 3 at one end side, and combined integrally to a locking base 5 at the other side. To the connecting parts 2a and 2b of the torsion bar 2, cuttings as the discriminating means are formed. The torsion bar 2 is work hardened by applying a preliminary twisting to plastic deform a molding article to be molded in a desired form by twisting before the assembly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an energy absorbing mechanism for a seat belt, and more particularly to an energy absorbing mechanism for a seat belt having a torsion bar capable of absorbing collision energy.

[0002]

2. Description of the Related Art Conventionally, a retractor of a seat belt device for holding a vehicle occupant or the like safely in a seat is a device that automatically retracts webbing when a seat belt is not used, and causes a sudden acceleration, collision or deceleration. An emergency lock-type retractor that effectively and safely restrains an occupant by using an emergency lock mechanism that physically locks the retractor by inertia sensing means that responds to the vehicle is used.

On the other hand, when the impact force due to the collision is extremely large, the webbing tension increases with the passage of time after the collision, so that the occupant's body suddenly decelerates, and the load applied to the occupant from the webbing is extremely large. growing. Therefore, when the load acting on the webbing is equal to or greater than a predetermined value, the seat belt is extended by a predetermined amount to provide an energy absorbing mechanism for absorbing an impact generated on the occupant's body, thereby making the occupant's body more reliable. There have been proposed various types of seat belt devices for protecting the vehicle. A seat belt retractor having such a configuration is described in Japanese Patent Publication No. 51-34606.
“Especially energy absorbing devices for safety belts” are known.

In the above energy absorbing device, a winding member (bobbin) serving as a portion where the energy absorbing device transmits a force.
And a holder (supporting member) rotatable with respect to the winding member, and a torsion bar (torsion bar) is arranged between the holder and the winding member. ing. When the gear is attached to the retractor of the seat belt device, the gear is locked by the locking lever, and is non-rotatably connected to the holder. On the other hand, the other end of the torsion bar is non-rotatably connected to the winding member in advance. Therefore, when torque in the webbing pull-out direction is further applied to the winding member, the torsion bar is twisted around its own axis and plastically deforms, so that the collision energy acting on the occupant's body is absorbed as deformation work of the torsion bar. Is done.

[0005]

However, the impact at the time of a collision differs depending on the vehicle structure, and in order to sufficiently protect the occupant's body, the energy absorbing load (the load acting on the webbing) is adjusted according to the vehicle characteristics. Must. Therefore, in the case of the energy absorption mechanism using the above-mentioned torsion bar, it is necessary to set the same shape but only a different shaft diameter or a different material in order to cope with the torsional torque of the different torsion bar for each vehicle type. There is.

However, in order to form a torsion bar having a different diameter or material of the torsion portion for each type of vehicle, a dedicated mold is required for each, which causes an increase in manufacturing cost.
Further, in order to obtain a high energy absorption load, the shaft diameter must be increased, and the entire apparatus becomes large and heavy. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide an energy absorbing mechanism for a seat belt which can adjust an energy absorbing load according to vehicle characteristics and is inexpensive to manufacture.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to provide a substantially cylindrical bobbin on which webbing is wound, a supporting member rotatable relative to the bobbin, and a supporting member and bobbin. And a torsion capable of absorbing collision energy acting on an occupant when a load greater than or equal to a predetermined value acts on the webbing and the support member and the bobbin rotate relative to each other in the event of a vehicle emergency. The energy absorption mechanism for a seatbelt is provided with an energy absorption mechanism for a seatbelt, wherein the torsion bar is work-hardened by plastic deformation in advance before assembly.

According to the above construction, the torsional torque of the torsion bar can be increased by pre-hardening by plastic deformation. Therefore, even if the shaft diameter is the same,
By adjusting the amount of plastic deformation in advance, the torsional torque of the torsion bar due to work hardening can be adjusted.
Preferably, the torsion bar is work-hardened by twisting plastic deformation of a molded product formed into a desired shape.

Further, preferably, the torsion bar is
The connecting portion between the support member and the bobbin has an uneven shape identifying means. Also, preferably, the torsion bar has at least one streak-like identification means in the twisted portion.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an energy absorbing mechanism for a seat belt according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a front vertical sectional view of a seat belt retractor 100 according to an embodiment of the present invention, and FIG. 2 is an overall perspective view of a torsion bar 2 shown in FIG.

[0011] The seat belt retractor 100
Is a substantially cylindrical bobbin 3 around which the webbing is wound, a retractor base 1 as a support member rotatable relative to the bobbin 3, and one end side (the right side in FIG. 1). A cylindrical torsion bar 2 integrally connected to the bobbin 3 and integrated with a disc-shaped locking base 5 at the other end (the left side in FIG. 1), and a webbing of the locking base 5 in a vehicle emergency. Emergency lock means 300 for preventing rotation in the pull-out direction.

The retractor base 1 is formed by press-forming a metal plate so that left and right side plates 1a and 1b rise from both sides of a back plate 1c fixed to a vehicle body and have a substantially U-shaped cross section. A torsion bar 2 combined with the bobbin 3 is rotatably bridged at a position facing the left and right side plates 1a and 1b. The retractor base 1
At one end of the torsion bar 2 through which the side plate 1a is inserted.
A known take-up spring device (not shown) that constantly urges the bobbin 3 in the webbing take-up direction via the torsion bar 2 is provided.

At one end of the torsion bar 2, there is provided a bobbin connecting portion 2a which is rotatable integrally with the bobbin 3, and at the other end, a locking base connecting portion which is rotatable integrally with the locking base 5. 2b.
Each of these connecting portions 2a and 2b has a cross-sectional shape formed into a hexagon. The bobbin coupling portion 2a has a hexagonal cross section, and is inserted into a hexagonal cross-section insertion hole 23a of a retainer 23 fitted to a hexagonal cross section fitting recess 3a formed at one end of the bobbin 3. , So that it is integrally rotatable with the bobbin 3. The retainer 23 is rotatably supported by the side plate 1b via a bush 24.

The locking base coupling portion 2b has a hexagonal cross-section, and is inserted into a hexagonal cross-section insertion hole 8a of a cylindrical boss portion 8 protruding from an end surface of the locking base 5 on the bobbin side. The locking base 5 is integrally rotatably connected. At the locking base side end of the bobbin 3, a fitting recess 9 for receiving the boss 8 of the locking base 5 is provided, and the bobbin 3 is rotated relative to the torsion bar 2 via the fitting recess 9. It is supported as much as possible.

Therefore, when the emergency locking means 300 is actuated in the event of a vehicle emergency such as a collision, the pawl 16 pivotally supported by the locking base 5 is engaged with the internal ratchet 21 of the internal ratchet 21 fixed to the side plate 1a. The rotation of the locking base 5 in the webbing pull-out direction is prevented. Therefore, bobbin 3 is retractor base 1
Is prevented from rotating in the webbing pull-out direction via the torsion bar 2.

Then, when a rotational torque exceeding a predetermined level acts on the bobbin 3 due to the load acting on the webbing, the bobbin 3 is rotated relative to the retractor base 1, and between the retractor base 1 and the bobbin 3. Since a torsional torque acts between the coupling portions 2a and 2b of the disposed torsion bar 2, the torsion portion 2c between the coupling portions 2a and 2b undergoes torsional deformation. Accordingly, the torsion bar 2 is provided with a seat belt energy absorbing mechanism 200 for absorbing impact energy acting on the occupant's body.
Is composed.

A stopper mechanism 400 is provided at a position where the locking base 5 and the bobbin 3 are opposed to prevent the torsion bar 2 from twisting more than a predetermined amount. When the torsion bar has a corner, the collision of the vehicle ends before the torsion bar is twisted, so that the stopper mechanism 400 can be omitted.

The torsion bar 2 shown in FIGS. 1 and 2 is made of mild steel as a metal which is easily twisted. Before the torsion bar 2 is formed into a desired shape as shown in FIG. Work hardening is performed by adding a pre-torsion that causes plastic deformation. That is, when a molded product of the torsion bar 2 as shown in FIG. 3 to which no pre-torsion is applied has a torsion torque curve as shown by a solid line in FIG. 4, the torque T ₁ or more at which plastic deformation starts the addition of the torque T ₂ as予捩the molded article, the torsion bar 2 will have a torsional torque curve as shown by a broken line in FIG. Therefore, the torsion bar 2 to which the pre-torsion is applied has a higher torsional torque when compared at the same torsional rotation speed than the molded product to which the pre-torsional is not added by the work hardening.

Therefore, the torsion bar 2 can adjust the torsional torque only by adjusting the pre-twist amount even if the torsion portion 2c has the same shaft diameter. Since it is possible to obtain a torque torsion bar, it is not necessary to use a dedicated mold, and the manufacturing cost can be reduced. Further, even if the set value of the energy absorption load is changed and the number of torsion bars with different torsional torque settings increases, it can be dealt with only by changing the pre-torsion amount, and the development period can be shortened. Furthermore, since a torsion bar having a small shaft diameter and a high torsional torque can be made, the entire retractor can be reduced in size and weight.

Further, the connecting portions 2a and 2b of the torsion bar 2 in the present embodiment have notches 1 as identification means.
0 and 11 are formed. These notches 10, 11
For example, in a molded product molded into a desired shape as shown in FIG. Therefore, after the pre-twist is applied as shown in FIG. 2, the notches 10 and 11 have different phases around the axis (a phase shift of about 60 degrees in the present embodiment).

Therefore, the torsion bar 2 can determine the pre-twist amount by the notches 10 and 11. If these notches 10 and 11 are detected by an electric sensor, a jig or the like, it can be used for automatic assembly or to prevent erroneous assembly. The means for identifying the uneven shape as described above is not limited to the notches 10 and 11, but as shown in FIG. 5, the projections 32 protruding from the coupling portions 31a and 31b of the torsion bar 31 are provided.
33 can also be used. In this case, the projections 32 and 33 of the torsion bar 31 made of mild steel are
When inserting and assembling the 1a and the coupling portion 31b into the insertion hole 23a of the retainer 23 and the insertion hole 8a of the locking base 5, respectively, they can be crushed and exert the effect of rattling.

The torsion bar 41 shown in FIGS. 6 and 7 is a molded product which is formed into a desired shape and is not pre-threaded.
Molding is performed so that a single ridge 42 serving as a streak-like identification means protrudes along the axial direction in 1c. in this case,
After the pre-torsion is applied as shown in FIG.
Since 2 extends helically along the outer peripheral surface of the torsion portion 41c, it is possible to determine in which direction the torsion bar 41 is pre-threaded.

Therefore, by reversing the direction of applying the pre-twist in the torsion bar 41 having the same shape, the torsion bar 41 can be used for a retractor having a different configuration such as a retractor for a driver's seat and a retractor for a passenger's seat. . Furthermore, the torsional rotation number of the torsion bar when absorbing the impact energy at the time of collision is set to 1 to 3 rotations depending on the type of the vehicle, but when the torsion bar 41 is provided, the actual torsion angle of the torsion bar 41 is set. Can be easily understood, and it is useful for confirming that the energy absorbing mechanism 200 has been reliably operated and for collecting impact data at the time of collision.

The above-mentioned streak-like identification means includes:
It is not limited to the ridge 42, and extends along the axial direction when the cross-sectional shape of the torsion portion 51c of the torsion bar 51 is polygonal (a regular hexagon in FIG. 8) as shown in FIG. A ridge line can also be used, and the direction in which the pre-twist has been applied can be determined, and the actual twist angle after the energy absorbing mechanism has been activated can also be determined based on the twist direction of the ridge line.

Further, in the above embodiment, the torsion bar is work-hardened by plastic deformation torsion of the molded article formed into a desired shape. Needless to say, the material may be hardened by plastic deformation by drawing. Furthermore,
The energy absorbing mechanism for a seat belt in the present invention is:
Unlike the seat belt retractor 100 of the above embodiment, it is not always necessary to combine the seat belt retractor with the seat belt retractor. For example, the support member may be arranged at the vehicle body fixing portion of the webbing, or may be combined with the buckle.
Further, the shape of the torsion bar is not limited to the shape of the above-described embodiment, but may take various shapes.

[0026]

As described above, in the energy absorbing mechanism for a seat belt of the present invention, the torsional torque of the torsion bar can be increased by work hardening by plastic deformation in advance. However, the torsional torque of the torsion bar due to work hardening can be adjusted by adjusting the amount of plastic deformation in advance.

Therefore, a torsion bar having all kinds of torsional torque can be obtained from one molded product, and a dedicated molding die is not required, and the manufacturing cost can be reduced.
Further, even if the set value of the energy absorption load is changed and the number of torsion bars with different torsional torque settings increases, it can be dealt with only by changing the pre-torsion amount, and the development period can be shortened. Furthermore, since a torsion bar having a small shaft diameter and a high torsional torque can be made, the whole apparatus can be reduced in size and weight.

Accordingly, it is possible to provide an energy absorbing mechanism for a seat belt which can adjust the energy absorbing load in accordance with the vehicle characteristics and is inexpensive to manufacture.

[Brief description of the drawings]

FIG. 1 is a front vertical sectional view of a seat belt retractor according to an embodiment of the present invention.

FIG. 2 is an overall perspective view of the torsion bar shown in FIG.

3 is an overall perspective view of a molded product of the torsion bar shown in FIG. 2 before work hardening.

FIG. 4 is a characteristic diagram showing a torsional torque curve of the torsion bar shown in FIG.

FIG. 5 is an overall perspective view showing a modified example of the torsion bar shown in FIG. 2;

FIG. 6 is a cross-sectional view showing another modification of the torsion bar shown in FIG.

7 is an overall perspective view of the torsion bar shown in FIG. 6 after work hardening.

FIG. 8 is a cross-sectional view showing another modification of the torsion bar shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Retractor base 2 Torsion bar 2a Bobbin connection part 2b Locking base connection part 2c Torsion part 3 Bobbin 5 Locking base 10 Notch 11 Notch 100 Retractor for seat belt 200 Energy absorption mechanism 300 Emergency locking means

Claims (1)

[Claims] 1. A substantially cylindrical bobbin on which webbing is wound, a support member rotatable relative to the bobbin,
The collision energy acting between the support member and the bobbin is torsionally deformed by the relative rotation between the support member and the bobbin due to the rotation of the support member and the bobbin in the event of a vehicle emergency. An energy absorbing mechanism for a seatbelt, comprising: a torsion bar capable of absorbing a force of the seatbelt, wherein the torsion bar is work-hardened by plastic deformation in advance before assembly.