Land vehicles – Wheeled – Attachment
Reexamination Certificate
2001-04-24
2003-07-29
Dickson, Paul N. (Department: 3618)
Land vehicles
Wheeled
Attachment
C280S805000, C280S806000, C280S801100, C280S802000, C242S379100, C297S474000
Reexamination Certificate
active
06598904
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a webbing take-up device which tenses a webbing in a direction of restraining a vehicle occupant at the time of rapid deceleration of a vehicle, and in particular, to a webbing take-up device which, at the time of impeding pulling-out of a webbing, can absorb energy while allowing the webbing to be pulled-out.
Further, the present invention relates to a vehicle equipped with this webbing take-up device.
2. Description of the Related Art
In a webbing take-up device, at the time of rapid deceleration of a vehicle, rotation of a spool (take-up shaft) in a webbing pull-out direction is locked such that pulling-out of the webbing is impeded. As this locking mechanism, a lock member is provided in a vicinity of a device frame at one end side of the spool. Due to this lock member being operated when the vehicle rapidly decelerates, rotation of the spool in the webbing pull-out direction is hindered.
Further, in such a webbing take-up device, at the time of impeding pulling-out of the webbing, a predetermined amount of pull-out of the webbing is permitted and energy is absorbed. There are devices in which, for example, a spool and a torsion bar disposed coaxially with the spool form the energy absorbing mechanism. Generally, the torsion bar is connected to a lock base and the spool such that the torsion bar and the lock base and the spool do not rotate relative to one another. One end portion of the torsion bar is connected to the spool, and the other end portion of the torsion bar is connected to a lock base to which a lock member is connected. The spool and the lock base usually rotate integrally via the torsion bar. However, at the time of a rapid deceleration of the vehicle, in a state in which rotation of the lock base in the webbing pull-out direction is hindered, the spool rotates in the webbing pull-out direction with respect to the lock base due to the webbing tensile force. At this time, the torsion bar twists, energy is absorbed, and a predetermined amount of rotation of the spool is permitted. The absorbed energy is determined by the product of the load applied to the webbing (the force limiter load) and the webbing pull-out amount (the amount of rotation of the spool). In the webbing take-up device, the force limiter load and the allowed amount of rotation of the spool (the limit of twisting of the torsion bar) are applied.
However, in such a conventional webbing take-up device, the force limiter load at the time of energy absorption is governed by the values of the properties of the material of the torsion bar and the dimensional configuration of the torsion bar. The force limiter load is a fixed value regardless of, for example, the inertial energy of the vehicle occupant such as the collision energy whose parameters are the weight and the physique of the vehicle occupant, the vehicle speed at the time of the collision and the like. Further, the force limiter load is a fixed value from the beginning to the end of energy absorption. Namely, in a conventional webbing take-up device, both during rapid deceleration of the vehicle and during the process of energy absorption, different force limiter loads cannot be selected.
However, if the force limiter load can be reduced (if a small force limiter load can be selected) at an appropriate time in the energy absorbing process, the webbing pull-out amount (the amount of movement of the vehicle occupant) can be suppressed by, at the initial stage of rapid deceleration of the vehicle, applying a large force limiter load so as to make the energy absorption amount per spool rotation amount (webbing pull-out amount) large. On the other hand, after a predetermined energy absorption (after a predetermined amount of energy has been absorbed), by reducing the force limiter load, the load applied to the vehicle occupant can be decreased.
In particular, in a vehicle equipped with an air bag device, by reducing the force limiter load immediately before contact of the air bag and the vehicle occupant, the total load applied to the vehicle occupant can be reduced, and there is less possibility that the vehicle occupant is injured, compared to the conventional device.
A webbing take-up device in which different force limiter loads can be selected in accordance with the inertial energy of the vehicle occupant has been contemplated. However, in order to be able to change the force limiter load in such a conventional webbing take-up device, for example, plural torsion bars are provided and combination of torsion bars which absorbs energy is changed, or torsion bars of different diameters are combined coaxially and the energy absorbing positions thereof are changed. Thus, these structures are complex.
SUMMARY OF THE INVENTION
In view of the aforementioned, a first object of the present invention is to provide a webbing take-up device which, with a simple structure, can select different force limiter loads at arbitrary times.
A second object of the present invention is to provide a vehicle which is equipped with the aforementioned webbing take-up device and an air bag device, and which can reduce the load applied to a vehicle occupant.
In order to achieve the above-described first object, a first aspect of the present invention is a webbing take-up device comprising: a cylindrical spool at which a webbing is taken-up and from which a webbing is pulled-out; a lock base provided at one end side of the spool so as to be coaxial with the spool and so as to be able to rotate relatively to the spool; a locking member which is connected to the lock base and which impedes rotation of the lock base in a direction of pulling out the webbing by engaging with a frame at a time when a predetermined acceleration is sensed; a torsion bar which is provided within the spool coaxially with the spool, one end of the torsion bar being connected to the spool, another end of the torsion bar being connected to the lock base, the torsion bar making the spool and the lock base rotate integrally in a normal state, and a state in which rotation of the lock base in the direction of pulling out the webbing is impeded by the locking member, the torsion bar being twisted due to webbing tensile force while making the spool rotate relatively with respect to the lock base in the direction of pulling out the webbing; at least one wire whose one end portion is fixed to the lock base and whose other end portion and an intermediate portion are inserted in the spool, and due to the at least one wire being pulled out from the spool at a time when the spool rotates relatively with respect to the lock base, the at least one wire generating a resistance force; and a cutting section which is able to cut the at least one wire at an arbitrary time.
The wire of the first aspect may be a rod-shaped member which does not easily deform (e.g., which does not deform by its own weight or due to force which can be applied by a human).
In the webbing take-up device of the first aspect, the spool and the lock base are connected via the torsion bar, and usually the spool and the lock base rotate integrally. Thus, usually, the webbing can be freely taken-up and pulled-out.
When the vehicle rapidly decelerates, the lock member operates to impede rotation of the lock base in the webbing pull-out direction. At this time, the webbing tensile force accompanying the inertial movement of the vehicle occupant is applied, via the spool, to the torsion bar as rotational force in the webbing pull-out direction. As a result, the spool rotates relatively to the lock base while the torsion bar is twisted. Further, when the spool begins to rotate relatively to the lock base, along with this rotation, the wire is pulled out from the spool while being drawn through (rubbed) at an exit portion of the spool, and is taken-up on the side surface of the lock base. In this way, while the twisting load of the torsion bar and the drawing-through (rubbed) load of the wire are applied to the webbing (the vehicle occupant) as a constant force li
Mori Shinji
Nagata Tomonori
Sumiyashiki Akira
Cole Thomas W.
Dickson Paul N.
Draper Deanne
Kabushiki Kaisha Tokai-Rika-Denki-Seisakusho
Nixon & Peabody LLP
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