Winding – tensioning – or guiding – Reeling device – With spring motor
Reexamination Certificate
1999-12-21
2002-06-18
Nguyen, John Q. (Department: 3653)
Winding, tensioning, or guiding
Reeling device
With spring motor
C280S805000, C280S807000
Reexamination Certificate
active
06405962
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a retractor (a winding device) for use with a seat belt webbing device and, in particular, to a retractor for use with a seat belt webbing which includes an energy absorbing mechanism using a torsion bar.
Conventionally, as a retractor for use with a seat belt webbing which is used to hold an occupant or the like of an vehicle in a seat safely, there are used many kinds of retractors of an emergency lock type which includes an emergency lock mechanism for locking a retractor physically by means of inertia sensing means capable of responding to sudden acceleration, vehicle collision or sudden deceleration, whereby the vehicle occupant can be restricted effectively and safely.
As a retractor of this emergency lock type, there is known a structure that a cylindrical-shaped bobbin around which a webbing can be wound is formed integrally of light material such as synthetic resin, a light alloy or the like, and a winding shaft serving as a strength member formed of steel material by forging is fitted or inserted into the bobbin and is then rotatably supported on a retractor base, thereby forming a light and high-strength winding shaft assembly.
And, the winding shaft includes lock means structured such that a locking base provided in one end portion thereof can be engaged with the engaging portion of the retractor base in a vehicle emergency to thereby prevent the winding shaft from rotating in the webbing pull-out direction thereof; that is, the winding shaft is structured such that, in a vehicle emergency, the locking base thereof can be engaged with the engaging portion of the retractor base to thereby prevent the winding shaft assembly against rotation in the webbing pull-out direction thereof.
By the way, in a retractor of an emergency lock type structured in the above-mentioned manner, as a fixing structure which is used to fix the base end portion of the webbing to the winding shaft assembly, there is known a fixing structure which is disclosed in Japanese Utility Model Unexamined Publication No. Sho. 60-87749 and the like.
In particular, as shown in
FIG. 1
, a winding shaft assembly
100
includes a bobbin
102
which is formed of light material in an integrally cylindrical shape and around the outer periphery of which a webbing
101
can be wound, and a winding shaft
103
which is formed of steel material and serves as a strength member assembled to the center hole of the bobbin
102
. Also, the bobbin
102
and winding shaft
103
respectively include slits
121
and
122
which respectively extend through the bobbin
102
and winding shaft
103
in the diameter directions thereof, so that the base end portion of the webbing
101
can be inserted through the slits
121
and
122
.
And, the base end portion of the webbing
101
is inserted from one opening end
121
a
of the slit
121
, is passed through the slit
122
, is further passed through the slit
121
, and is projected from the other opening end
121
b
thereof; and, at the same time, a substantially rod-shaped fixing pin
130
having an outside diameter larger than the gap of the two slits is inserted into a loop-shaped portion
110
formed by turning back and sewing the base end portion of the webbing
101
to thereby form a large diameter portion
120
, so that the base end portion of the webbing
101
is prevented against the removal from the winding shaft
103
. That is, the webbing
101
can be secured to the winding shaft assembly
100
.
The above-mentioned fixing structure not only is easy to secure a sufficient fixing strength but also is so simple in structure that it can be assembled easily and efficiently.
On the other hand, in a retractor of an emergency type, when the emergency lock mechanism is operated due to a collision to prevent the webbing from being pulled out, if the shock due to the collision is very heavy, with the passage of time after the collision, a tensile force acting on the webbing increases to thereby cause a sudden deceleration in the body of the vehicle occupant, so that a load given to the occupant from the webbing becomes extremely large. In view of this, recently, there have been proposed various kinds of retractors for use with a seat belt webbing; in particular, each of them includes an energy absorbing mechanism which, when the tensile force acting on the webbing reaches or exceeds a previously set given value, pulls out the webbing a given amount to thereby absorb the shock produced in the body of the occupant, so that the body of the occupant can be protected more positively.
And, as the retractor for use with a seat belt webbing including the above-mentioned energy absorbing mechanism, there are proposed various retractors (see Japanese Patent Unexamined Publications Nos. Hei. 6-156884, Hei. 7-47923, and the like; each of them comprises a substantially cylindrical shaft assembly around which a webbing can be wound, a torsion bar which can be inserted through the center hole of the winding shaft assembly in such a manner that one end thereof is connected to the winding shaft assembly in a mutually unrotatable manner and the other end thereof is connected to the locking base of the winding shaft assembly in a mutually unrotatable manner, and emergency lock means which, in a vehicle emergency, engages the locking base with the retractor base of the retractor to prevent the rotation of the torsion bar to thereby prevent the winding shaft assembly against rotation in the webbing pull-out direction thereof, whereby, when the emergency lock means is put into operation, if a tensile force acting on the webbing exceeds a previously set given value, then not only the shock energy can be absorbed by means of the torsional deformation of the torsion bar but also the tensile force acting on the webbing can be controlled.
As described above, the structure for absorbing the collision energy by means of the torsional deformation of the torsion bar inserted through the center hole of the winding shaft assembly not only is higher in the freedom of design with respect to the energy absorbing amount and the pull-out amount of the webbing, but also is simpler in structure and is thus more suitable for the reduction of the size of a retractor, when compared with a structure for absorbing the collision energy by means of the plastic deformation of the winding shaft assembly itself, retractor base or the like.
However, in such a webbing fixing structure as shown in
FIG. 1
, when trying to insert the above-mentioned torsion bar into the center hole of the winding shaft assembly, the torsion bar cannot be inserted because the webbing is in the way. Therefore, for example, as disclosed in the above-cited Japanese Patent Unexamined Publication No. Hei. 6-156884 and the like, there is employed a structure in which the torsion bar is inserted into the cylindrical portion formed by turning back and sewing the base end portion of the webbing to prevent the webbing against removal, thereby being able to secure the base end portion of the webbing to the winding shaft assembly.
However, as a result of this, after the cylindrical portion of the webbing is disposed within an inwardly spreading opening formed in the winding shaft assembly, the torsion bar must be inserted into the present cylindrical portion, which lowers the efficiency of the assembling operation of the winding shaft assembly. Also, if the base end portion of the webbing is pulled in the removing direction thereof due to a tensile force acting on the webbing in a vehicle collision, then a bending force and friction resistance are applied to the torsion bar, which has influences on the energy absorbing load to be deal with by means of the torsional deformation of the torsion bar.
SUMMARY OF THE INVENTION
In view of the circumstances of the prior art, the present invention aims at eliminating the drawbacks found in the above-mentioned conventional retractors. Accordingly, it is an object of the invention to provide a retractor for use with a seat belt webbing which not only can ab
Crowell & Moring LLP
Nguyen John Q.
NSK Autoliv Co. Ltd.
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