DE443252C - Automatic temperature controller for electric ovens in connection with a temperature measuring device - Google Patents

Description

GERMAN EMPIRE

ISSUED APRIL 23, 1927

REICH PATENT OFFICE

PATENT LETTERING

- JVl 443 252 CLASS 21: h GROUP 13

(E 33821Vlll \ 2ih)

Elektro-Schalt-Werk A. G. in Göttingen.

Automatic temperature controller for electric ovens in connection with a temperature measuring device.

Patented in the German Empire on March 11, 1926.

Automatic temperature regulators, which by the pointers making a contact of a Measuring device are put into action are known.

However, the forces acting on the light pointer are too small to be sure establish mechanical contact. Even at

in that a transformer from the secondary side high voltage is caused to spark over by the pointer of the temperature measuring device, so that the pointer no mechanical contact with the poles of the secondary winding, but that he is merely maintaining

Very high currents can easily be one) one or two air gaps to bypass burning of the contact points occur, wel- | kung serves, whereby in the primary winding 20 10 ches the operation of the. Apparatus in question j an increase in the current strength is shown. The essence of the invention consists »now j will call, which considerably depends on the idle

Amperage differs and which serves to one with the primary winding of the transformer series-connected relay to respond. On the drawing show: ' Fig. Ι a circuit arrangement,

Fig. 2 shows the sparkover point on the measuring device.

A transformer α of low power is provided with a secondary winding b , ίο which generates a voltage of a few thousand volts. This voltage is high enough to bridge an air gap of one to several millimeters. The primary winding C of the transformer is calculated for the respective mains voltage. The no-load current of the transformer is very low, while at the moment of the flashover of the secondary voltage, the primary current strength increases considerably. The facility is based on this. In the primary circuit is the current coil of a relay d, which in turn controls the heating circuit, e.g. B. an electric furnace e, closes or interrupts or changes. When the transformer is idle, the relay does not respond, but it is activated as soon as the primary current reaches its maximum value as a result of the secondary voltage being flashed over.

The overturning of the secondary tensioning by the pointer can be among any other Executions, e.g. B. be carried out as follows:

The ends of the secondary winding b are enclosed in a high-quality insulator / which is movably arranged above the scale g of the temperature measuring device h. The ends emerge on a surface / out of the insulator in such a way that they just terminate with the surface, that is, do not protrude. This surface i faces the pointer k and is located a short distance above or below it, so that the pointer can slide freely past the surface.

The contact ends are in the pointer axis, so that the pointer forms a bridge between the contact ends, with only two small air gaps / and m the galvanic short-circuit of the circuit is prevented. However, as soon as the pointer comes close enough to the contact ends, • the air gaps are bridged by two small arcs and the primary current increases. If the pointer moves away from the contacts, the arcs break and the primary current falls again to a very low value.

Of course you can also use the pointer yourself use as one pole of the secondary winding. Likewise, two or more pairs of contacts can be made be arranged on the scale if z. B. the temperature limits are further apart. Then the relay is to be designed as a changeover relay with two or more coils, or it is several groups of transformers are arranged.

The pointer itself can be coated with a small piece of precious metal at the point where it forms the bridge, but this is not absolutely necessary because the secondary current is only extremely low and it will not create any burn marks on the pointer.

The system described above offers the guarantee of absolute accuracy with great simplicity (as far as the temperature measuring device shows exactly) and maximum operational safety.

Claims (4)

Patent claims: i. Automatic temperature regulator for electric ovens in connection with a temperature measuring device, characterized in that a transformer («) of high voltage on the secondary side is caused to spark over by the pointer (k) of the temperature measuring device (A) so that the pointer does not have any mechanical contact with the poles of the secondary winding, but that it only serves to bridge while maintaining one or two air gaps (t-tri) , which causes an increase in the current in the primary winding (c) that deviates significantly from the no-load current and the for this purpose, one connected in series with the primary winding of the transformer. Bring relay (d) to respond. 2. Automatic temperature regulator according to claim 1, characterized in that for compliance with the maximum and minimum value of the temperature two similar ones Systems are applied. 3. Automatic temperature regulator according to claim 1, characterized in that several simple or changeover relays can be fed from one transformer. 4. Automatic temperature regulator according to "claim i, characterized in that the relay (d) is used to regulate the fuel supply. For this purpose ι sheet of drawings. HERLIN. OPRINT IN THE II