Winding – tensioning – or guiding – Reeling device – With particular drive
Reexamination Certificate
2001-12-26
2004-03-09
Rivera, William A. (Department: 3654)
Winding, tensioning, or guiding
Reeling device
With particular drive
Reexamination Certificate
active
06702219
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a seatbelt retractor for use in a passenger car, etc., in order to ensure the safety of vehicle occupants.
A seatbelt retractor must be installed in order to secure the safety of a vehicle occupant upon an accident such as collision, and various types thereof have been developed. An example of the simplest structure thereof is shown in FIG.
16
.
A spring cover
41
, which is a supporter at one side of the seatbelt retractor, is provided with a bearing
41
a
arranged therein, into which a shaft
42
a
of a spool
42
is fitted so as to rotate while a force in the retracting direction is applied to the shaft
42
a
by a spring. A seatbelt is wound around the spool
42
.
Inside the spool
42
, a concave fitted portion (not shown) is formed, into which one end of a torsion bar
43
is fitted. The other end of the torsion bar
43
is fitted into a concave fitted portion (not shown) formed in a locking base
44
. A shaft
44
a
of the locking base
44
passes through a hole
45
a
of a lock gear
45
so as to fit into a bearing (not shown) of a retainer
46
, which is a supporter on the other side of the seatbelt retractor.
Such a mechanism results in supporting the spool
42
at its rotating shaft by the spring cover
41
and the retainer
46
and rotating the spool
42
so as to retract the seatbelt by means of the spring. The spring cover
41
and the retainer
46
are fixed at both ends of a base frame
48
, so that the spool
42
is accommodated within the base frame
48
.
In these structural elements, the locking base
44
and the lock gear
45
are rotatable by a predetermined angle, so that the lock gear
45
is urged by a spring
49
relative to the locking base
44
in the direction pulling out or withdrawing the seatbelt so as to approach the limit of the relative rotation.
When the seatbelt is withdrawn in a normal state, since there is no rotational resistance against the lock gear
45
, the lock gear
45
can not overcome the urging force of the spring
49
. As a result, the lock gear
45
rotates integrally with the locking base
44
.
Even when the locking base
44
is rotated in the withdrawing direction as the spool
42
is rotated by the spring force, the lock gear
45
rotates integrally with the locking base
44
because the lock gear
45
is designed to approach the limit of the rotation relative to the locking base
44
in this direction as mentioned above.
When abrupt retraction force to the seatbelt is produced due to a collision or the likes, a flywheel
50
accommodated within the lock gear
45
is displaced by overcoming the urging force of a spring
51
, so that the lock gear
45
can not rotate relative to the retainer
46
, thus of the seatbelt being stopped.
Then, the rocking base
44
rotates relative to the lock gear
45
against the urging force of the spring
49
. A mechanism is constructed such that a pawl
52
accommodated in the locking base
44
is protruded outside by this relative rotation, and a gear of the externally protruded pawl
52
is brought into engagement with a gear section
48
a
formed in the base frame
48
, also stopping the rotation of the locking base
44
.
Accordingly, rotation of the torsion bar
43
is also stopped and the spool
42
is allowed to rotate only by an angle corresponding to a twist of the torsion bar
43
. Therefore, the spool
42
is thereafter rotated under a tension increasing as the seatbelt is withdrawn. The locking mechanism described above is generally called as “a locking mechanism by a web sensor”.
The description above only illustrates an outline of the seatbelt retractor and there are complex mechanisms for use as a mechanism for stopping the rotation of the lock gear
45
by the movement of the flywheel
50
and a mechanism for protruding the pawl
52
outside, for example. However, the seatbelt retractor is known and in common use, so that more detailed description may not be necessary for those skilled in the art, and moreover, it is irrelevant to the principal part of the present invention, so that the more detailed description is omitted.
However, in the conventional seatbelt retractor, since the lock mechanism is operated after the seatbelt is actually withdrawn suddenly, a time lag in operating the lock mechanism may be developed. There is also a problem that when the seatbelt is withdrawn in a state that a motor shaft is connected to the spool, a force for withdrawal or retraction is required and a force for retracting the seatbelt is not sufficient. Furthermore, when the seatbelt is rapidly withdrawn during wearing the seatbelt, the lock mechanism may also be operated. This results in for an occupant feeling uncomfortable or unpleasantness.
The present invention has been made in view of such situations, and it is an object of the present invention to provide a seatbelt retractor which can promptly operate a lock mechanism upon an emergency.
It is another object of the invention to provide a seatbelt retractor which eliminates uncomfortable feeling or unpleasantness to an occupant caused by unnecessary operation of locking mechanism upon wearing the seatbelt without reducing the retractor efficiency.
SUMMARY OF THE INVENTION
In order to solve the problems described above, a seatbelt retractor has a mechanism for retracting a seatbelt by a motor. The seatbelt retractor comprises a switching mechanism for switching on and off a power transmission route between the motor and a spool around which the seatbelt is wound, in which the power transmission route between the motor and the spool is connected only when the motor rotates in the retracting direction, and a ratchet mechanism in which, during operation, the spool rotates only in the seatbelt-retraction direction and during non-operation, the spool is allowed to rotate in any directions (the first aspect).
In the mechanism, when the motor does not rotate in the retracting direction, the power transmission route between the motor and the spool is not connected by the switching mechanism of the power transmission route. Therefore, the mechanical power transmission between the motor and the spool is not performed. At this time, by turning the ratchet mechanism off, the spool can freely rotate without any load applied thereto by the motor and rotational disturbance by the ratchet mechanism. Accordingly, the seatbelt is retracted only by a retracting force due to the spring torque, so that a vehicle occupant will not feel uncomfortable.
When a collision detecting device attached to a vehicle detects abrupt braking, a large acceleration, and so forth so as to determine that there is a possible collision, the device sends a signal to the motor to retract the seatbelt simultaneously with putting the ratchet mechanism into an operating state. Then, the power transmission route between the motor and the spool is connected by the switching mechanism of the power transmission route, so that the spool is rotated by the winding force of the motor so as to retract the seatbelt. Due to operation of the ratchet mechanism, the spool rotates only in the seatbelt-retraction direction but not in the seatbelt-withdrawing direction, enabling a vehicle occupant to be securely restrained to a seat.
A seatbelt retractor can be equipped with a switching mechanism of a power transmission route which is driven by a rotational force of a motor in the seatbelt-retraction direction so as to connect the power transmission route between the motor and the spool having the seatbelt wound therearound.
In the first aspect, turning on (connection) and off (disconnection) the power transmission route is operated by the rotational torque of the motor, so that an actuator driven by the other power for operating the switching mechanism of the power transmission route, such as an electromagnetic solenoid, is not required. Therefore, the switching mechanism of the power transmission route cab be comprised of the smaller number of parts, and a simplified structure and cost reduction can be achieved
Kanesaka & Takeuchi
Rivera William A.
Takata Corporation
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