Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
2000-06-01
2002-06-11
Dougherty, Thomas M. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
Reexamination Certificate
active
06404105
ABSTRACT:
The invention relates to a contactor/circuit breaker mounted on a main pulsating, preferably alternating, electric power line, and its activation method. According to other aspects, the invention relates to a device for activating a movable part intended for a contactor/circuit breaker type mechanism and to the application of piezoelectric motors to the activation of electrical contacts.
Contactors/circuit breakers are already known comprising two types of contact, one active, the other passive, whose active contacts are activated by an electromechanical system such as an electromagnet.
Such mechanisms are designed to provide both the putting into and taking out of service of the circuit and its protection in the event of overcurrent in the main power line.
However, this type of mechanism does not give complete satisfaction, since it has on the one hand a significant mechanical and electrical inertia, and on the other hand a sensitivity to the electromagnetic field created by the main power line, these two phenomena preventing accurate control in time and space of the movable contacts.
This results in the occurrence of significant electric arcs at the time of opening the contacts and limiting of the current range within which the circuit is protected.
The invention therefore aims to remedy these drawbacks.
To that end, and according to a first aspect, it provides for a device for activating a movable part intended for a contactor/circuit breaker type mechanism in which the activation means comprise at least one piezoelectric motor driven by control means.
According to a second aspect, it provides for a contactor/circuit breaker type mechanism mounted on a main pulsating, preferably alternating, power line comprising two types of contact, one active, the other passive, the active contacts being associated with opening and closing activation means comprising at least one piezoelectric motor driven by control means.
According to a first variant, the piezoelectric motor is a linear motor and the active contacts are associated with one end of a contact carrier arm mounted rotationally around an axis, the activation means being disposed in proximity to the second end of the contact carrier arm.
According to a second variant, the piezoelectric motor is a rotary motor and the active contacts are associated with one end of a contact carrier arm mounted rotationally around an axis, the activation means being on the axis of rotation of the contact carrier arm.
In these two variants, a return spring can be associated with the end of the contact carrier arm situated on the opposite side to the active contacts with respect to the axis of rotation.
In one embodiment, the means of activating the active contacts comprise two piezoelectric linear motors, one for opening, the other for closing.
According to a variant, the active contacts are associated with one end of a contact carrier arm mounted rotationally around an axis, one of the piezoelectric linear motors being disposed on the same side of the axis of rotation as the active contacts, and the other being disposed in proximity to the second end of the contact carrier arm. A return spring is associated with the contact carrier arm in order to facilitate the opening and closing of the contacts by the activation means.
In another embodiment, the passive contacts are mounted translationally on a spring along the axis of displacement of the active contacts.
In one embodiment, the control means of the piezoelectric motor comprise, in series, a mechanical and/or electronic trigger circuit for requesting opening/closing of the main power line, a switching device, a programmable delay line and an electric generator energizing the piezoelectric motor.
In a supplementary embodiment, the control means of the piezoelectric motor comprise, in series, a device detecting overcurrent in the main power line, a switching device, a programmable delay line and an electric generator energizing the piezoelectric motor.
In a variant of these two embodiments, the control means of the piezoelectric motor comprise a single switching device, a single programmable delay line and a single electric generator energizing the piezoelectric motor.
The switching device comprises a means of detecting the current and/or voltage of the main power line and a comparator which energizes the control circuit of the piezoelectric motor when the value of the current and/or voltage detected is equal to a certain reference value.
The device detecting overcurrent in the main power line comprises a means of detecting the current in the main power line and a comparator which energizes the control circuit of the piezoelectric motor when the value of the current detected is greater than or equal to a certain threshold value.
According to a third aspect, the invention provides for the application of piezoelectric motors to the activation of electrical contacts.
According to a fourth aspect, the invention provides for a method of activating a mechanism according to the invention, in which, the main circuit being closed, it comprises the following successive steps:
mechanical and/or electronic triggering of the request for opening the main power line;
detecting the current in the main power line;
switching the first time the current in the main power line goes to the reference value;
energizing the delay line programmed previously according to the reference value and the speed of displacement of the piezoelectric motor;
energizing the electric generator;
triggering the opening of the contacts at an instant where the current in the main power line is equal to a certain value, notably close to zero.
When the main circuit is open, the method comprises the following successive steps:
mechanical and/or electronic triggering of the request for closing the main power line;
detecting the voltage in the main power line;
switching the first time the voltage in the main power line goes to the reference value;
energizing the delay line programmed previously according to the reference value and the speed of displacement of the piezoelectric motor;
energizing the electric generator;
triggering the closing of the contacts at an instant where the voltage in the main power line is equal to a certain value, notably close to zero.
In a variant, when the main circuit is closed, the method comprises the following successive steps:
detecting the current in the main power line;
comparing the measured current value with a threshold value;
If the value of the current measured on the main power line is greater than the threshold value:
switching the first time the current in the main power line goes to the reference value;
energizing the delay line programmed previously according to the reference value and the speed of displacement of the piezoelectric motor;
energizing the electric generator;
triggering the opening of the contacts at an instant where the current in the main power line is equal to a certain value, notably close to zero.
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patent: 3989964 (1976-11-01), Gikow et al.
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patent: 4473859 (1984-09-01), Stone et al.
patent: 4620124 (1986-10-01), Farrall et al.
patent: 4976553 (1990-12-01), Yamaguchi et al.
patent: 0 163 497 (1985-04-01), None
patent: 62-44-19 (1987-02-01), None
patent: 62-48220 (1987-03-01), None
Dougherty Thomas M.
Nawrocki, Rooney & Siverston, P.A.
Norbert Beyrard France
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