Electricity: motive power systems – Automatic and/or with time-delay means – Plural – diverse conditions or with time-delay means
Patent
1996-05-15
1998-03-31
Masih, Karen
Electricity: motive power systems
Automatic and/or with time-delay means
Plural, diverse conditions or with time-delay means
318560, 318600, 318567, 36447428, 395 89, G05B 500
Patent
active
057342440
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention is concerned with a safety appliance for manipulatable parts which, through motor-driven operation, are movable toward a closure edge, in particular, for use with window regulators and sliding roofs of automotive vehicles.
BACKGROUND OF THE INVENTION
Electromotive drives for windows and sliding roofs are being increasingly assembled in automotive vehicles to relieve the driver or front-seat passenger from the effort involved with opening and closing a window or a sliding roof. Although these drives are an attractive feature, they must be prevented from closing or opening under certain conditions.
It has, therefore, been previously suggested to provide safety appliances intended to prevent items or parts of the body from being clamped. For example, DE-OS 37 36 400 sets forth that it is known to monitor the consumption of current and/or the number of revolutions of the driving motor or to use pressure- or temperature-sensitive sensors responding and generating a signal if foreign matter is present during the closure process, between the window edge and the closure edge of the frame.
Both the number of revolutions and the consumption of current of the driving motor are means for indirectly measuring the forces acting on the sliding member. Apart from the difficulty directly measuring absolute values, the problem involved with safety devices based on the evaluation of absolute quantities resides in determining the response threshold at which the anti-clamping system is to respond. A low-level threshold may cause the switch-off means to respond even if there is no danger for an item to be clamped. For, the lateral guide of the pane or sliding roof also exerts forces on the pane that vary in accordance with the ambient conditions. For example, at low temperatures, running of the guide is substantially less smooth. If the threshold is high, the anti-clamping means will respond be too late.
It has already previously been suggested (European patent application No. 0442388) not to determine the absolute quantity but rather the change from one measuring interval to the next. However, even then it is difficult to determine the response threshold. If it is set too small, the switch-off device may become operative upon the occurrence of usual fluctuations in the resistance of the pane guide. If the threshold is set too high it may be that the anti-clamping system does not respond once a soft item is clamped because the force during squeezing together a soft body, from one measuring point to the other, only irrelevantly increases with the consequence that the anti-clamping system does not respond although very high forces act upon the clamped-in item which forces have, however, been built up in small increments.
According to the description of the state of art the problem encountered resides in providing a safety appliance insuring a sensitive and early response which only occurs if an item is actually in danger to be clamped.
It is, therefore, suggested by the invention to provide a measuring instrument detecting in successive measuring intervals a quantity representing the operating force on the movable part. Moreover, an evaluator is provided determining the difference between the measured quantity in a start-up interval and the measured quantity in a final interval, with the drive being switched off as soon as the difference exceeds a response threshold. The start-up interval is defined in that respectively a quantity is measured in the measuring intervals between the start-up interval and the final interval which exceeds the value in a preceding measuring interval by a predetermined amount, i.e. the difference threshold. The evaluation pattern can be used irrespective of the absolute quantity actually detected. It can be the current consumption or power absorption of the motor or the number of revolutions of the motor. Also, the forces applied to the sliding member can be directly measured.
The basic principle of the invention resides in that the changes in the force, from one measu
REFERENCES:
patent: 5054494 (1991-10-01), Lazzaro et al.
patent: 5265194 (1993-11-01), Kanamori
English Translation of the International Preliminary Examination Report for Application PCT/EP94/02868.
Search Report of the German Patent Office for Application No. P4330904.6.
Gakenholz Werner
Lill Anton
Philipps Werner
ITT Automotive Europe GmbH
Lewis J. Gordon
Masih Karen
Twomey Thomas N.
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