Electrical transmission or interconnection systems – Personnel safety or limit control features
Patent
1993-12-07
1998-10-13
Shoop, Jr., William M.
Electrical transmission or interconnection systems
Personnel safety or limit control features
49 27, 49 28, 318283, 318469, F05F 1502
Patent
active
058216448
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a safety system for a passage closure such as a gate, window, door, sliding roof or the like having a drive, the maximum permissible load value of which can be set and having a control device by which the drive can be switched off, switch-off occurring when the maximally permissible load value has been reached, at which time a signal is sent to the control device.
2. Description of the Prior Art
Power-operated devices, such as gates, doors or windows, cooperate with an electromechanical drive, for example, which, in the case of garage doors, consists of a guide rail mounted on the garage ceiling, in which a carriage which is connected to the door by hinged bars is guided movable in a longitudinal direction by a drive motor and through an interlocked element. In this case, the interlocked element extends straight and parallel to the guide rail and is resiliently and fixedly suspended at both ends by springs. The drive is furthermore equipped with a blockage and obstacle circuit, such as described in German Patent Publication DE 35 46 282 C2. A garage door drive of this type is very responsive and operates safely, but it has the disadvantage that the drive cannot distinguish between the door resting on the ground and being in contact with an obstacle.
A method for switching off or reversing an electric motor for the drive of a movable passage closure is disclosed in German Patent Publication DE 35 14 223 C2, in which the increase of the current used by the motor is monitored and, when a preselected set value is exceeded, the motor is shut off or reversed into the opposite direction. This method can be used when the passage closure is a device which is relatively small and of light weight, such as windows, sliding roofs, or the like. However, this method cannot necessarily be employed with large devices, such as garage doors which encounter obstacles during closing, particularly when these obstacles are bodies, located in the area of the compression or closing edge, which can easily be destroyed.
SUMMARY OF THE INVENTION
Accordingly, it is an object of this invention to provide a safety device which, on the one hand, can determine whether the passage closure closes or has closed in accordance with the operating conditions or, on the other hand, can determine whether the passage closure is in contact with an obstacle. The safety device is such that when the passage closure comes into pressure contact with an obstacle, the latter is released. It is a further object of this invention to embody the safety device in such a way that the user is always informed whether the safety device and/or the drive device are operating correctly.
These objects are attained with the safety device in accordance with one embodiment of this invention comprising a sensor disposed in the area of compression and/or closing edge of the passage closure which, when encountering an obstacle, emits a signal to a control device. Upon reaching a maximally permissible load value, the control device generates a time differential, .DELTA.T.sub.actual =T.sub.2 -T.sub.1 and compares the value of said time differential with a preselected value, T.sub.preselected. If .DELTA.T.sub.actual is greater than T.sub.preselected, then the direction of the passage closure is changed.
Accordingly, the safety device of this invention comprises a time measuring device which is switched on by a signal S.sub.1 at a time T.sub.1 and measures the time .DELTA.T.sub.actual =T.sub.2 -T.sub.1 within which the operational load on the drive device is exceeded and emits a signal S.sub.2 within the time period T.sub.2. As a rule, these time periods are in the range of milliseconds. If the passage closure assumes the extended position, that is, it rests on the ground, the operational load is exceeded within a very short time after the signal S.sub.1 has been emitted, so that the drive device is shut off and the movement of the passage closure is interrupted. If there is an obstacle, for exam
REFERENCES:
patent: 4369399 (1983-01-01), Lee et al.
patent: 4638433 (1987-01-01), Schindler
patent: 4896714 (1990-01-01), Ellis
patent: 5027552 (1991-07-01), Miller et al.
Nippon Denso K.K. and Makoto Asou, "Automatic Opening and Closing Device of a Window for Vehicle", Patent Abstracts of Japan, vol. 9, No. 219 (1985).
Kaplan Jonathan S.
Shoop Jr. William M.
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