Winding – tensioning – or guiding – Reeling device – With spring motor
Reexamination Certificate
2000-09-28
2002-07-09
Jillions, John M. (Department: 3653)
Winding, tensioning, or guiding
Reeling device
With spring motor
C280S806000
Reexamination Certificate
active
06416008
ABSTRACT:
FIELD OF INVENTION
The present invention generally relates to a seatbelt retractor which takes up a seatbelt so as to be windable and extractable and more specifically relates to a seatbelt retractor having a seatbelt load restricting mechanism.
BACKGROUND OF THE INVENTION
Conventionally, seatbelt devices are provided in vehicles, such as automobiles, in order to restrain the passengers in the event of emergencies. The seatbelt devices help restrain passengers in their seats, thereby protecting the passengers.
Modern seatbelt devices typically have seatbelt retractors for taking up the seatbelt. The seatbelt retractor is arranged such that, in the event the seatbelt is not being worn, the seatbelt is taken up on a spool. In the event that the seatbelt is worn, the seatbelt is extracted and worn by the passenger and excess webbing is taken up on the spool. Further, the seatbelt retractor is arranged such that a lock mechanism operates in the event of an emergency. The lock mechanism hinders the rotation of the spool in the direction of extracting the seatbelt, thereby impeding the extraction of the seatbelt. Thus, the seatbelt restrains and protects the passenger in the event of an emergency.
With conventional seatbelt retractors and seatbelt devices, a rapid vehicular deceleration occurring while the seat belt is worn results in great inertia that moves the passengers forwards. Thus, an increased load is placed on the seatbelt and the passenger is subjected to an increased shock force from the seatbelt. This shock force on the passenger is not necessarily a problem. However, it is desired to reduce this force. Accordingly, conventional seatbelt retractors have been developed with a torsion bar, so as to restrict the load placed upon the seatbelt in the event of an emergency while the seatbelt is worn.
FIG. 11
is a cross-sectional diagram illustrating an example of a seatbelt retractor having such a torsion bar. In the Figure, reference numeral
1
denotes a seatbelt retractor,
2
denotes a frame in the shape of a box with one end open and
3
denotes a seatbelt. Numeral
4
denotes a spool which is rotatably supported by both side walls of the frame
2
. The spool
4
takes up the seatbelt
3
. Numeral
5
denotes a deceleration detecting means. The detecting means
5
detects vehicular deceleration generated in the event of an emergency and operates accordingly. Numeral
6
denotes a lock mechanism. The deceleration detecting means
5
activates the lock mechanism
6
. The lock mechanism
6
hinders the rotation of the spool
4
in the direction of extracting the belt. Numeral
7
denotes a torsion bar which is movably mounted. The torsion bar
7
passes through the center of the spool
4
in the axial direction and rotationally links the spool
4
and the lock mechanism
6
. Numeral
8
denotes a first spring for perpetually pressing the spool
4
in the direction of taking up the belt. A second spring
9
works in conjunction with the first spring
8
via a bushing
10
. Numeral
11
denotes a pretensioner which generates belt take-up torque in the event of an emergency. Numeral
12
is a bushing for transmitting the seatbelt take-up torque from the pretensioner
11
to the spool
4
.
The lock mechanism
6
is provided with a locking base
14
which is capable of integrally rotating with a later-described first torque transmitting shaft
17
of the torsion bar
7
. The lock mechanism
6
also holds a pawl
13
in a manner capable of rocking. The torsion bar
7
is provided with a lock gear
6
a which normally rotates integrally with the torsion bar
7
but stops in the event of an emergency by the operation of the deceleration detecting means
5
. The lock gear
6
a generates a relative rotational difference with the torsion bar
7
and engages the pawl
13
with inner teeth
19
on the side wall of the frame
2
. The engagement of the pawl
13
with the inner teeth
19
hinders rotation of the locking base
14
. Thus, the spool
4
stops in the direction of extracting the seatbelt.
A first torque transmitting portion
17
, which engages the locking base
14
in a manner incapable of relative rotation, is formed on the torsion bar
7
. A second torque transmitting portion
18
is formed on the torsion bar
7
. The second torque transmitting portion
18
engages the spool
4
in a manner incapable of relative rotation.
The spool
4
is perpetually pressed by the spring force of the spring
8
in the direction of taking up the seatbelt. The spring
8
acts via the bushing
10
, torsion bar
7
, second torque transmitting portion
18
of the torsion bar
7
, and the bushing
12
. Also, in the event of the pretensioner
11
operating, the belt take-up torque generated at the pretensioner
11
is transmitted to the spool
4
via the bushing
12
. Thus the spool
4
takes up a predetermined amount of the seatbelt
3
.
With conventional seatbelt retractors
1
thus configured, the seatbelt
3
is completely taken up by the pressing force of the spring means
8
when the seatbelt is not being worn. Extracting the seatbelt
3
at a normal speed for wearing causes the spool
4
to rotate in the seatbelt extracting direction, which allows the seatbelt
3
to be extracted smoothly. An tongue (not shown) provided to the seatbelt
3
is inserted into and retained by a buckle fixed to the vehicle body. The portion of the seatbelt
3
which has been excessively extracted is taken up by the spool
4
by the pressing force of the spring means
8
. Thus, the seatbelt
3
is adjusted so that the passenger does not feel too tight.
In the event of an emergency, the seatbelt take-up torque generated by the pretensioner
11
is transmitted to the spool
4
. The spool
4
takes up the seatbelt
3
by a predetermined amount, thereby securely restraining the passenger. Under rapid vehicular deceleration generated in the event of an emergency, the deceleration detecting means
5
activates the lock mechanism
6
. That is, the rotation of the lock gear
6
a
in the direction of extracting the seatbelt is obstructed by the operation of the deceleration detecting means
5
. The pawl
13
of the lock mechanism
6
rotates and engages the inner teeth
19
of the side wall of the frame
2
. This impedes the rotation of the locking base
14
in the direction of extracting the seatbelt. The spool
4
alone rotates in the direction of extracting the seatbelt relative to the locking base
14
. Subsequently, the spool
4
rotates in the direction of extracting the seatbelt while twisting the torsion bar
7
. Therefore, the load placed on the seatbelt
3
is restricted by the twisting torque of the torsion bar
7
. Thus, the shock to which the passenger is subjected is absorbed and alleviated.
An energy absorbing (EA) mechanism is formed by the torsion bar
7
. The properties of load restriction under this EA mechanism at this time (hereafter also referred to as EA load) are such that the load restricted by the torsion bar
7
gradually increases as the stroke of relative rotation of the spool
4
to the locking base
14
increases. This is shown by the dotted line in FIG.
2
(
a
). The load later becomes a constant value F
1
.
Additionally, the conventional seatbelt retractor
1
is arranged so that the locking base
14
of the lock mechanism
6
rotates in the direction of extracting the seatbelt relative to the lock gear
6
a if seatbelt is rapidly extracted. Accordingly, the pawl
13
of the lock mechanism
6
engages the inner teeth
19
of the side wall of the frame
2
in the same manner as above. Thereby, the rotation of the locking base
14
is obstructed. Therefore, the rotation of the spool
4
in the direction of extracting is obstructed via the torsion bar
7
, and extraction of the seatbelt is obstructed.
With such a conventional seatbelt retractor
1
, a single EA load is set by the torsion bar
7
alone, and the kinetic energy of the passenger is absorbed by only this one EA load. A minimum and constant EA load F
1
is selected for this EA load. It is chosen such that the kinetic energy of the
Fujii Hiroaki
Kajiyama Hiroshi
Jillions John M.
Takata Corporation
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