Winding – tensioning – or guiding – Reeling device – With spring motor
Reexamination Certificate
2000-05-16
2001-09-18
Walsh, Donald P. (Department: 3653)
Winding, tensioning, or guiding
Reeling device
With spring motor
C242S382400, C180S268000, C280S807000, C200S06158R
Reexamination Certificate
active
06290160
ABSTRACT:
The present invention relates to a belt retractor comprising a frame, a belt reel rotatably mounted about an axis in the frame, a control disc coaxial with the belt reel and a reduction gear unit which translates the angle of rotation of the belt reel into a reduced angle of rotation of the control disc.
BACKGROUND OF THE INVENTION
In a belt retractor the total range of angular rotation of the belt reel is dictated by the condition of the belt webbing in its fully coiled and fully uncoiled condition. Within this range of angular rotation various relationships exist between the absolute angle of rotation of the belt reel and characteristic conditions of the belt system. Thus, zero angle of rotation (belt webbing fully coiled) is an indication that the belt is not in use. At maximum angle of rotation (belt webbing fully uncoiled) a switching action may be introduced to translate the belt retractor into the automatically blocked condition which is suitable for example for restraining loads or child seats. Between these extreme positions various characteristic conditions may be defined which, where necessary, in conjunction with other parameters, more particularly seating posture, seat occupancy and the like, may be associated with special switching positions in which activating various switching actions is expedient, it being especially desirable for the system to “see” the conditions in which activation of an air bag is to be inhibited, examples of which are the use of child seats, incorrect seated posture (leaning forward) and belt buckled with seat empty. Recognizing such conditions is only possible with adequate reliability when the angle of rotation of the belt reel can be sensed with high accuracy. It is known (e.g. DE 298 20 086.4) to translate the total range of angular rotation of the belt reel by means of a reduction gear unit to a single revolution of an indexing disc. Since, however, the absolute angle of rotation of the belt reel is a multiple of 360°, each angle on the indexing disc corresponds to an accordingly greater angular range of the belt reel rotation so that the indexing positions cannot be sensed with the desired accuracy.
BRIEF SUMMARY OF THE INVENTION
The invention makes available a belt retractor of the aforementioned kind in which the absolute angle of rotation of the belt reel may be established with high accuracy by uncomplicated technical means. In the belt retractor in accordance with the invention the control disc comprises at least one cutout window between two detector elements, the first of which detector elements is non-rotatably connected to the belt reel and the second of which is arranged non-rotatable relative to the frame, the window provided on the same radius relative to the axis as these sensor elements. When a detector element arranged on the belt reel arrives at a position opposite the frame-fixed detector element, a signal pulse is generated, but only then when the window of the control disc is located between the sensor elements to thus permit communication between them. The control disc and the window therein thus permit selection of a portion of the range of total angle of rotation of the belt reel, it being within this selected range of angular rotation which may correspond more particularly to one full revolution of the belt reel, that the absolute angle of rotation of the belt reel is sensed without any reduction by a gear since the detector elements produce a pulse precisely then when the sensor on the belt reel is located opposite to the sensor fixed to the frame.
By providing a plurality of detector elements distributed about the circumference of the belt reel in the preferred embodiment of the belt retractor various rotary positions may now be reliably and precisely sensed within an absolute revolution of the belt reel.
In a preferred further embodiment of the belt retractor a plurality of detector elements are arranged on the same radius and non-rotatable with respect to the frame. With a suitable number of detector elements fixed to the frame, each of which is capable of sensing a full revolution of the belt reel, all relevant rotary positions of the belt reel may be sensed with high accuracy.
Further features and advantages of the invention read from the following description and are evident from the drawings illustrating by way of example an embodiment of the invention and to which reference is made in the description.
REFERENCES:
patent: 5501293 (1996-03-01), Borjesson
patent: 5765774 (1998-06-01), Maekawa et al.
Miller Jonathan R.
Tarolli, Sundheim, Covell Tummino & Szabo L.L.P.
TRW Occupant Restraint Systems GmbH & Co. KG
Walsh Donald P.
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