DE1154579B - Temperature controlled electric hotplate - Google Patents

Description

Temperature Controlled Electric Hotplate The invention relates to on a temperature-controlled electric hotplate with parboiling and continued boiling area, wherein the temperature sensor consists of a temperature-dependent one arranged in the hotplate Resistance is in series with a bimetallic heating resistor and this series connection in parallel with another bimetal heater and the one in series with the temperature sensor lying resistance in the boiling-out stage with a switching contact is bridged.

It is a switching arrangement for the infinitely variable regulation of the energy supply electric hotplates known, in which the heating resistance of the heater is a Parallel connection of a dimensional resistor also located in the heater high positive temperature coefficient and a first auxiliary heating resistor for the bimetal switch is connected upstream and a second, by means of a switch Disconnectable auxiliary heating resistor is provided for the bimetal switch, wherein in the parallel connection of the dimensional resistor and the first auxiliary heating resistor, the second Auxiliary heating resistor is connected in series with the dimensional resistor and can be short-circuited in stages is. However, this known circuit arrangement only serves the purpose of the lower Control limit except for a ratio of switch-on and switch-off times of around 1: 100 reduce, so that, for example, for steaming or keeping food warm the lowest possible temperature of the hotplate is guaranteed.

However, this known switching arrangement would be replaced by a time switch Switching from the parboiling level to the continued boiling range would be done without any intervention required in the regulator switch, in the parboiling stage the entire switching arrangement to be bridged by a contact activated by the timer, as the continued cooking area, d. H. the position of the bypass switch before the timer is switched on must be set and therefore not in the parboiling stage of the bridging switch can act more as such. However, this then has the consequence that in the parboiling stage no temperature protection provided by the temperature sensor for the controller plate is available.

This disadvantage is now eliminated according to the invention in that in on known way for the automatic switching from parboiling to continued cooking range a time switch is provided and that the time switch has either two normally open contacts is provided, one of which is parallel to the one with the temperature sensor in series lying resistance and the series connection of the other working contact with a Resistance is parallel to the temperature sensor, or provided with a changeover contact is and a series resistor is connected in front of the bimetal heating, in which a position of the changeover contact of the timer bridges the resistor and in the other position the series resistor is bridged.

By this measure it is achieved once that it is possible that Use a timer to switch from the parboiling level to the continued boiling range without having to intervene in the controller switch, the bridging of the entire switching device is required and also the There is a possibility to use the continued cooking area before the timer starts turn on and on the other hand it is achieved that during the parboiling process at least partially there is a temperature protection of the regulator hotplate, since the temperature sensor is partially effective.

Further advantageous details of the invention are set out below Hand of the embodiments illustrated in the drawing described.

In Fig. 1, 1 is a radiator, for. B. that of a hotplate, in whose supply line the parallel connection of a bimetallic heater I labeled 2 with the series connection of a temperature sensor 3 consisting of a temperature-dependent resistor with a positive temperature coefficient and a resistor labeled 4 , which is designed here as bimetallic coating II. A contact 5 is provided parallel to the bimetal heater 4.

Further, located in the supply line: a actuated by a bimetal regulator contact 6 two Anschaltkontakte 7 and actuated by the not shown in the drawing timer OFF contact B. According to the invention parallel to the temperature sensor 3, a shunt resistor 9, and a this anschaltender, controlled by the timer working contact 10 and A second normally open contact 11, which is also controlled by the timing element, is provided parallel to contact 5.

The mode of operation of this arrangement is as follows: First, a certain continued cooking level is selected on the control switch, the contact 5 being opened and the two connection contacts 7 and the control contact 6 being closed. At the same time, the switching path of the bimetal element is set via a cam. If you now switch on the parboiling stage with the timer, contacts 8, 10 and 11 are closed. As can be seen, the temperature sensor 3 is effective. Since the contact 5 is bridged by the contact 11 at the same time, the pear-shaped heating 4 does not have any effect, ie, despite the setting to the continued cooking level, the controller or the controller contact 6 does not clock.

After a time selected on the timer has elapsed, the normally open contacts 10 and 11 are opened. The bimetal heater 4 is now also traversed by current, which leads to the closing and opening of the regulator contact 6 and a certain amount of energy is supplied to the radiator 1 according to the setting. Finally, after a switch-off time also preselected on the timer, the switch-off contact 8 is opened and the power supply to the radiator 1 is thus interrupted.

Another possible circuit is shown in FIG. In this case, a series resistor 12 is connected in series with the bimetal heater 2 , which can be bridged by a contact 11a, which is designed here as a changeover switch.

This circuit works as follows: First, the desired continued cooking level is switched on again at the control switch, i.e. contact 5 is opened and contacts 6 and 7 are closed. When a certain boiling time is selected on the timer, the changeover contact 11a is placed upwards, so that the bimetallic heater 4 is bridged and the series resistor 12 is switched on. At the same time, the switch-off contact 8 is closed and the total time is set.

As a result, the current flowing through the bimetal heater 2 is kept so small that the bimetal element is heated so strongly that the regulator contact 6 opens only when the temperature is too high, ie when the temperature sensor 3 has a very high resistance.

After expiration of the heat-up time of the changeover contact 11 a is set by the timer down, so that now the resistor 12 is bridged and the time required for the subsequent cooking stage bimetallic heater 4 is turned on. As a result, the power supplied to the bimetal element is so great that the regulator contact 6 is continuously opened and closed. After the total time has elapsed, contact 8 is then also opened, so that the cooking process is ended.

A clock mechanism is the most appropriate timing element.

As already indicated, instead of the bimetal heater 4, a simple resistor that does not act on the bimetal can also be provided. This is bypassed in the parboiling level and is switched on in the continued cooking area. In the latter case, it only acts as a series resistor for the temperature sensor 3, so that a larger proportion of the current flows through the bimetallic heater 2 , so that the clocking process is thereby made possible.

Claims (3)

PATENT CLAIMS: 1. Temperature-controlled electric hotplate with parboiling and continued boiling area, the temperature sensor consisting of a temperature-dependent resistor arranged in the hotplate, which is in series with a bimetal heating resistor and this series connection is parallel to another bimetal heating and which is in series with the Temperature sensor lying resistance in the parboiling stage is bridged with a switching contact, characterized in that a timer is provided in a known manner for the automatic switching from parboiling level to continued cooking range and that the timer is either provided with two working contacts (10,11) from where one (11) is parallel to the resistor (4) in series with the temperature sensor (3) and the series connection of the other working contact (10) with a resistor (9) is parallel to the temperature sensor (3), or with a changeover contact ( 11 a) is provided and in front of the Bimetallbeh heating (2) a series resistor (12) is connected, the resistor (4) being bridged in one position of the changeover contact of the timer and the series resistor (12) being bridged in the other position. 2. Cooking plate according to claim 1, characterized in that the resistor (4) lying in series with the temperature sensor (3 ) is designed as an additional bimetal heater. 3. Hotplate after Claim 1 or 2, characterized in that a third, in the time switch Supply line lying contact (8) is provided for controlling the total cooking time. Considered publications: German Patent Nos. 647 699, 748 125; German interpretative document No. 1065 539.