Motor vehicles – With belt or harness for restraining occupant – and means...
Reexamination Certificate
2000-08-03
2002-12-31
Dickson, Paul N. (Department: 3619)
Motor vehicles
With belt or harness for restraining occupant, and means...
C280S806000, C280S807000, C297S480000
Reexamination Certificate
active
06499554
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a seat belt retractor mounted on a vehicle, such as automobile, for controlling unwinding and winding of a seat belt for restraining and protecting a passenger and, more specifically, the invention relates to a seat belt retractor for restraining and protecting a passenger more reliably by controlling tension of the seat belt based on the conditions outside the vehicle or the operating conditions of the seat belt.
The seat belt device that has been mounted conventionally on the vehicle, such as automobile, protects a driver and passenger from being jumped out from the seat in case of emergency such that an abrupt deceleration is applied to the vehicle in the event of a collision or the like by restraining the driver or passenger with a seat belt.
The seat belt device of this type is provided with a seat belt retractor for winding the seat belt. The seat belt retractor comprises energy application means, such as flat spiral spring, for urging a reel for winding the seat belt at all the time in the normal winding direction. The seat belt is wound on the reel by the energy applied by the energy application means when not in use. In contrast, in use, the seat belt is unwound against the energy applied by the energy application means and worn by the passenger. The seat belt retractor prevents unwinding of the seat belt in case of emergency as stated above by actuating locking means to prevent the reel from rotating in the unwinding direction. This ensures that the seat belt restrains and protects the passenger in case of emergency.
In the conventional seat belt device of the type described above, an almost constant tension is applied to the seat belt by the energy from the energy application means when the seat belt is in use. Therefore, the seat belt retractor always acts in the same manner independently of the conditions of the vehicle itself and surrounding the vehicle. However, although the conventional seat belt device ensures protection of the passenger in case of emergency as stated above, it can not be said that the seat belt is controlled comfortably for the passenger in the case other than emergency as stated above. In addition, it is preferable to protect the passenger more positively by restraining the passenger securely in case of emergency.
A passenger restraining and protecting system is provided in Japanese Unexamined Patent Publication (KOKAI) No. 9-132113, wherein the restraint and protection of the passenger are carried out more efficiently and more comfortably for the passenger by controlling the rotation of the reel of the seat belt retractor and adjusting the belt tension by a motor with consideration of the conditions between the vehicle itself and outer objects.
On the other hand, when the locking means of the seat belt retractor is actuated in case of emergency and prevents the reel from rotating in the unwinding direction as stated above, the passenger tends to move forward by an inertial force and is subjected to a significant impact by the seat belt. Therefore, a seat belt retractor comprising a belt load limiting mechanism (EA mechanism) is also proposed, wherein a torsion bar is provided between the reel and the locking means in order to protect the passenger from the impact so that the torsional deformation of the torsion bar absorbs the impact energy and relieves the impact applied to the passenger.
Since a large number of components is used in the belt tension control mechanism in the passenger restraining and protecting system disclosed in Japanese Unexamined Patent Publication (KOKAI) No. 9-132113, and these components perform complicated actions, the seat belt retractor becomes significantly large size and the operational control is complicated.
However, the space in the interior of the vehicle where the seat belt retractor is mounted is limited, and is quite small, and the space for mounting the seat belt retractor is strictly limited when considering the habitability of the interior of the vehicle. Therefore, it is preferable to provide a seat belt retractor that can accommodate the strict limitation of the mounting space by downsizing it as small as possible, while allowing control of the belt tension based on the conditions between the vehicle itself and the outer objects.
In addition, since the operational control of the belt tension control mechanism is quite complicated, the drive control of the motor is not simple and, in addition, the drive circuit of the motor is complicated and costly.
In view of such conditions, it is an object of the invention to provide a seat belt retractor, wherein the structure of the belt tension control mechanism is simplified by reducing the number of components as small as possible, and the control of the belt tension control mechanism is reliable and simple.
Further objects and advantages of the invention will be apparent from the following description of the invention.
SUMMARY OF THE INVENTION
In order to overcome the problems described above, a seat belt retractor according to a first aspect of the invention comprises a reel for winding a seat belt, reel urging means for urging the reel in the seat belt winding direction, locking means provided between a frame and the reel for allowing rotation of the reel in a normal condition, and preventing the rotation of the reel in the belt unwinding direction when necessary, and a belt tension control mechanism for controlling the belt tension of the seat belt. The belt tension control mechanism comprises a motor for generating a rotational torque, a power transmission path having an OFF-state in which the rotational torque is not transmitted between the motor and the reel, and an ON-state in which a rotational torque is transmitted between the motor and the reel, and a power transmission path switching mechanism for selectively switching the power transmission path between the ON-state and the OFF-state. The power transmission path switching mechanism is actuated by the rotational torque of the motor.
In a second aspect of the invention, the power transmission path includes a power transmission gear mechanism; the power transmission path switching mechanism includes a switch gear axially movable for controlling the operation of the power transmission path switching mechanism; and the gear of the power transmission gear mechanism and the switch gear are both formed in helical gears and are engaged with respect to each other. When the gear of the power transmission gear mechanism is rotated by the rotational torque of the motor, the switch gear is rotated, and the axial tension generated in the axial direction by the rotation of both gears moves the switch gear in the axial direction, thereby actuating the power transmission path switching mechanism and setting the power transmission path into the ON-state.
In a third aspect of the invention, the power transmission path father includes a speed reducing mechanism for reducing the speed of the rotation of the motor transmitted from the power transmission gear mechanism and transmitting it to the reel; and the speed reducing mechanism includes a sun gear, a ring-shaped internal gear rotatably mounted and having ratchet teeth on the outer periphery thereof and internal teeth on the internal periphery thereof, a planetary gear to be engaged with the sun gear and with the internal gear, a carrier for rotatably supporting the planetary gear and transmitting the rotation thereof to the reel, and a speed reducing gear provided so as to rotate with the sun gear as a single unit for receiving the rotation of the motor transmitted from the power transmission gear mechanism. The power transmission path switching mechanism further comprises a stop lever rotatable between a non-engaging position in which the stop lever is not engaged with the ratchet teeth and the engaging position in which the stop lever is engageable with the ratchet teeth, and a plunger for placing the stop lever to the non-engaging position in the normal state in which the s
Tanaka Koji
Tanji Hiromasa
Yano Hideaki
Dickson Paul N.
To Toan C
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