Winding – tensioning – or guiding – Reeling device – With spring motor
Reexamination Certificate
2000-02-24
2001-12-11
Rivera, William A. (Department: 3653)
Winding, tensioning, or guiding
Reeling device
With spring motor
Reexamination Certificate
active
06328242
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a seat belt retractor.
DISCUSSION OF THE PRIOR ART
A seat belt retractor of this type is known from EP 0 893 313 A2. The known seat belt retractor has a belt reel which is rotatably mounted on a retractor frame and on which a seat belt can be wound and unwound. A biased motive spring acts on the belt reel in order to produce a pulling force acting on the seat belt. During the winding and unwinding of the belt webbing, the pulling force acting on the seat belt follows a characteristic curve which is dependent on the extracted length of belt webbing. An electric motor drive with which the pulling force produced by the motive spring can be adjusted is also provided.
SUMMARY OF THE INVENTION
In the present invention the mode of operation of the motive spring is improved in that the pulling force which it produces on the belt webbing follows a characteristic curve corresponding to room temperature (approximately 20° C.) at any temperature. Measurements have shown that at different temperatures, for example in a temperature range of −40° C. to +80° C., the pulling force acting on the belt webbing follows different characteristic curves in hysteresis form as a function of the extracted length of the belt webbing during winding and unwinding. At temperatures different from room temperature, the comfort in wear of the applied seat belt is considerably impaired with known seat belt retractors. The invention rectifies this in that, owing to the drive acting on the motive spring, in particular an electric motor drive, the spring force is so adjusted that the pulling force acting on the belt webbing follows a characteristic curve corresponding to room temperature, at any temperature differing from room temperature.
A temperature-measuring device can be provided for this purpose, which measures the ambient temperature in the region of the seat belt retractor. The force of the motive spring is adjusted by the drive as a function of the measured temperature.
This can be affected in that, when the ambient temperature is lower than room temperature, the bias of the motive spring is reduced by the drive, and when ambient temperatures are higher than room temperature, the bias of the motive spring is increased by the drive. For this purpose, the fixing point at which the motive spring is supported externally can be rotated round the spring core in the corresponding direction of rotation.
According to a further embodiment, the characteristic curve corresponding to room temperature can be stored in an electronic memory and the respective force or bias of the motive spring can be adjusted as a function of the setpoints predetermined by the stored characteristic curve for the pulling force acting on the belt webbing. A force measuring device which supplies the measured value in the control circuit for adjusting the force of the motive spring can be provided in the flow of force between the motive spring and the seat belt or also at the point where the bias of the motive spring is supported.
REFERENCES:
patent: 4561677 (1985-12-01), Kawai
patent: 4902039 (1990-02-01), Kawai et al.
patent: 5628470 (1997-05-01), Ray et al.
patent: 5816522 (1998-10-01), Krambeck et al.
patent: 6211793 (2001-04-01), Smithson
patent: 2742676 (1977-09-01), None
patent: 4112620 (1991-04-01), None
patent: 4302042 (1993-01-01), None
patent: 0893313 (1998-07-01), None
Breed Automotive Technology Inc.
Drayer Lonnie
Rivera William A.
Vrioni Beth
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