Electricity: circuit makers and breakers – Centrifugal – Liquid contact
Patent
1982-01-26
1983-03-22
Tolin, G. P.
Electricity: circuit makers and breakers
Centrifugal
Liquid contact
318793, 310 68E, 73549, H01H 3510
Patent
active
043777317
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a device for automatically interrupting the supply of electric power to a motor when this latter is locked rotationally under the action of a mechanical resistance applied in opposition to the torque exerted by this motor.
The invention is also directed to the use of a device of this type for automatically interrupting the current supply to a motor which controls opening and closing of a door, especially a garage door when this latter is at the end of its opening or closing movement.
In the event that the opening of a door such as a garage door, for example, is controlled by an electric motor, starting and stopping of the motor are controlled by a simple switch in the majority of instances. At the end of travel of the door, this electric motor is locked against rotation. In order to prevent damage to the motor, the supply of electric power to this latter must be cutoff as soon as the motor has been locked rotationally. Many safety systems have been proposed for this purpose and have the effect of dispensing with the need for any manual action by the user in order to cut-off the electric power supply to the motor at the ends of travel of the object which is driven by the motor.
These devices comprise end-of-travel switches of the mechanical or electromechanical control type. These devices have the disadvantage of being complicated and costly. In consequence, these devices are reserved for doors which have very large dimensions, are heavy and costly.
Devices of this type which are also known comprise a mass which is displaceable under the action of a centrifugal force in order to close or open an electric contact. The disadvantage presented by these devices takes the form of deficient sensitivity which often arises from defective guiding of the member used for ensuring electrical contact and which results in harmful friction and energy losses.
The object of the present invention is to overcome the above-mentioned disadvantage by producing a device for automatically interrupting the supply of electric power to a motor, which is simple and inexpensive to construct while being extremely sensitive.
In accordance with the invention, the device for automatically interrupting the supply of electric power to a motor when this latter is locked under the action of a mechanical resistance, comprising masses coupled for rotation with the motor and displaceable under the action of the centrifugal force generated at the time of this rotation in order to put the electric power supply of the motor in circuit and in order to put this power supply out of circuit when said centrifugal force drops, is characterized in that it comprises a body of revolution fixed on one of the ends of the motor shaft and provided with recesses for said masses, a disk which is free with respect to this shaft and rests against that face of the body in which the entrance of the recesses for said masses are formed and masks said entrances and a cap covering said disk and attached to the body, which is provided on the face remote from the body of revolution with a central protuberance whose apex is in contact with a conductive strip of the switch, said central protuberance of the disk being capable of fitting within a complementary opening formed in the end-wall of the cap.
By means of the device in accordance with the invention, intervention by the user is limited to actuation of a member such as a push-button for initiating start-up of the motor. This push-button can be released by the user as soon as the supply of electric power is produced by closing of the electric contact controlled automatically by the mass which is displaceable under the action of centrifugal force.
When a mechanical resistance is applied in opposition to the torque exerted by the motor, for example at the end of the opening or closing movement of a door, the centrifugal force drops, which automatically initiates opening of the electric contact and causes the electric power supply of the motor to be put out of circuit.
The device in accordance with t
REFERENCES:
patent: 2187207 (1940-01-01), McCabe
patent: 3043926 (1962-07-01), Rabeux
patent: 3176522 (1965-04-01), Quenneville
patent: 4107483 (1978-08-01), Jouret
Faiveley S.A.
Tolin G. P.
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