Electricity: electrical systems and devices – Control circuits for electromagnetic devices – For relays or solenoids
Patent
1994-05-26
1996-06-18
Fleming, Fritz M.
Electricity: electrical systems and devices
Control circuits for electromagnetic devices
For relays or solenoids
307116, 307140, H01H 4722
Patent
active
055284493
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to an arrangement for isolating control devices from the mains in cases where the internal operating voltage is supplied by means of a mains-bound voltage source.
BACKGROUND ART
Control devices of this kind are used in many fields of engineering, including applications in living rooms and bedrooms.
For instance, it is common for modern seating or beds to be fitted with drive motors for adjustment. Low-voltage DC motors are used for this purpose. Miniature transformers are installed to reduce the mains voltage to the necessary operating voltage. These transformers are usually connected to the mains voltage, and the no-load current of the transformer flows at all times, even when no adjustment is being made, this entailing disadvantages in terms of costs and the environment.
As these transformers are usually also located in the direct vicinity of combustible material and in the immediate sphere of action of persons, there is additionally constant potential danger potential as a result of the risk of fire or electric shock.
Furthermore, the transformer generates a magnetic field, the negative effects of which on the human body, at least in the case of long-term exposure, can no longer be ruled out according to the latest scientific evidence. Moreover, frequently unavoidable humming noises disturb the persons in the room.
DISCLOSURE OF THE INVENTION
The task of the invention is now to create an arrangement for isolating control devices from the mains, by means of which isolation from the mains takes place during times at which no control functions are to be performed and which implements connection to the mains upon receipt of control commands, thus avoiding the disadvantages of continuous mains operation.
In accordance with the invention, the task is solved by the arrangement for isolating control devices from the mains displaying a relay with at least one relay-actuated switch which is in the OFF position when not excited, is located in the mains-side supply lead and possesses an auxiliary power source which is wired in parallel with the mains-bound voltage source and is connected to the control input of the relay via a switch.
The mains power is thus fundamentally isolated from the mains-bound voltage source, meaning that the control device cannot be supplied with an operating voltage via this source, although this is also not necessary as long as no control operations, or at least none requiring a great amount of power, are to be triggered.
Only when power is to be supplied via the mains is the relay excited via the auxiliary power source, thus switching the relay-actuated switch or switches to the ON state and connecting the voltage source on the mains side. The control device is supplied with an operating voltage via the mains-bound voltage source as a result. Even high-power control operations can subsequently also be performed. The auxiliary power source remaining in the parallel circuit has no effect on the function.
In one favourable configuration of the invention, a switch which triggers the functions of the circuit arrangement is connected to the control input of the relay.
The result of this is that, on the one hand, the arrangement pursuant to the invention can be installed with only little additional circuitry and, on the other hand, disconnection or reconnection of the mains always takes place automatically when the switch is operated, meaning that additional manual operations can be dispensed with.
As the control operations to be performed usually have a relatively short time limit, another configuration of the invention according to the invention is characterised in that a push-button 16 is connected to the control input of the relay.
In favourable configurations of the invention, the auxiliary power supply takes the form of a battery or a capacitor, which preferably has a low leakage current.
In one favourable configuration of the invention, the auxiliary power source consists of a capacitor with a battery connected in parallel.
The special advant
REFERENCES:
patent: 3344313 (1965-04-01), Kraus, Sr.
patent: 3886376 (1975-05-01), Asija
patent: 4617501 (1986-10-01), Smith
patent: 4730089 (1988-03-01), Pepper
patent: 4994726 (1991-02-01), Tamura et al.
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