DE29801994U1 - Electric oven - Google Patents

Description

'Electric oven'

The invention relates to an electric oven with top heat and bottom heat heating elements and a grill integrated in the oven of the type specified in the preamble of claim 1.

One problem with conventional electric ovens is that, due to the type of heating, relatively long heating times are often required to bring the oven to the desired operating temperature when it is cold. This means that relatively large amounts of energy are also required to heat up the elements in the oven, such as racks, baking trays, the metal walls of the baking tray, etc.

An electric oven of the generic type is already known from the applicant's DE-295 19 816-Ul, which also seeks to find a solution to reduce the heating-up time and energy consumption, which is achieved by switching additional heating on and off. A circuit for heating an oven is also shown in DE-42 37 570-Al or DE-26 35 220-Al, the latter essentially relating to a safety device for the oven compartment of electric ovens. The state of the art also includes US-4 535 226, which in particular describes the switching on and off of

Top, middle and bottom heat in an oven revealed.

The object of the invention is to create a solution with which a rapid heating of such an oven is possible using simple means, which at the same time is also suitable for fully automatic operation.

In an electric oven of the type described above, this object is achieved according to the invention by a rapid heating circuit for the simultaneous operation of the grill and the bottom heat in the rapid heating phase and switching off the grill when the desired baking chamber temperature is reached by a rapid heating relay for switching from grill/bottom heat heating elements to top heat/bottom heat heating elements and/or hot air heating elements in the rapid heating circuit.

Such a rapid heating circuit, which combines the grill and the bottom heat, makes rapid heating possible with simple means, because with normal radiator outputs, e.g. a grill with 2200 W plus bottom heat with 1300 W, the total output is 3500 W, which in a three-phase power network with 16 A circuit breakers still makes heating possible without the need for special equipment.

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If an electronic timer was used in the applicant's generic application, this is replaced here by a 230 V relay with self-holding. The relay is made self-holding by a so-called rapid heating button, the relay's switching contacts switch to the rapid heating output. When the desired temperature is reached, an oven thermostat interrupts the self-holding and thus switches off the rapid heating process. The exclusively temperature-dependent assignment enables optimal functionality at any desired temperature.

The invention provides a switchover circuit from grill to top heat element when the desired oven temperature is reached. This switchover circuit makes fully automatic operation possible, which results in a very convenient way of using the oven, because the person using the oven does not have to pay attention to optical or other display elements on the oven in order to switch from a rapid heating phase to the normal baking phase, for example.

The oven can be conveniently equipped with a circuit with a rapid heating button for switching the relay for rapid heating, whereby in a further embodiment the circuit can be equipped with an optical display when actuated.

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can be equipped with the rapid heating system and/or operation.

Further details, features and advantages of the invention will become apparent from the following description and from the drawing.

Fig. 1 shows a circuit variant of an electric oven according to the invention and

Fig. 2 shows another variant of the electric oven rapid heating circuit.

In Fig. 1 and 2, under the pure circuits, the respective switching logic of the oven is shown as well as a list of components.

The operation of the circuit shown in Fig. 1 is as follows:

Fig. 1 shows a circuit for rapid heating with a self-holding relay.

In this switching variant, the cable connection between the oven selector switch (Sl ... 11) and the top heat

Heating element (h2) the changeover contact (Rl) of a relay. After pressing the rapid heating button (T) with the conventional oven program switched on, the relay (R) switches (R2). The upper heat heating element (h2) is de-energized, in return the grill (h3) is switched on and is parallel to the lower heat heating element (hl). The relay is set to self-hold via a locking contact (SIl) in the oven selector switch.

The locking contact is only closed in conventional operation, i.e. in other operating modes, self-holding and thus rapid heating are not possible. This circuit arrangement means that the oven has an increased heating capacity, i.e. the heating process up to the temperature set on the oven thermostat (th) is accelerated.

Once the desired oven temperature is reached, the thermostat (Th) switches off and thereby interrupts the power supply to the relay. The relay drops out and switches back from grill to top heat heating.

After switching the thermostat back on within the temperature control, the oven continues to heat with normal heating power. If the rapid heating button (t) is accidentally pressed again without the

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If the temperature setting of the thermostat (Th) has been increased, the increased power is switched on again in the post-heating phase of the temperature control. However, this is only available for a short time until the thermostat is switched off again and therefore has little influence on the temperature control.

The circuit described here therefore meets the requirements mentioned at the beginning:

1. Shortening the heating time

2. Less heating energy consumption

3. Simple operation by pressing a button, then automatic operation

4. Incorrect operation is not possible.

Fig. 2 shows a circuit for rapid heating with electronic control. In this circuit variant, too, the rapid heating process is switched from top heat to grill via a relay. In principle, the design and mode of operation are comparable to the circuit described above. However, due to electronic control, the circuit described below is more convenient.

The rapid heating process is also limited to conventional oven operation. After switching on the

oven (conventional), a display (L) assigned to the rapid heating button (T) flashes within a set time (e.g. 10 seconds). Pressing the button during this time starts the rapid heating. After the desired oven temperature has been reached, the control electronics switch the relay (R) so that the grill (h3) is switched off again and the top heat element (h2) is switched on.

Compared to the solution described in Fig. 1, this variant offers the following options due to the control electronics and the data stored in the processor:

- The rapid heating process can be interrupted at any time without switching off the oven program.

- Optical and acoustic signals (e.g. in the event of incorrect operation) are possible.

- After the rapid heating process has ended, pressing the heating button again without first setting the oven selector switch to the O position will not cause the relay to switch.

- The rapid heating process can be made dependent on the difference between the oven target temperature and the actual temperature.

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to Fig. 1

Oven switching logic

Operating mode S1 S2 S3 S4 S5 S6 S7 S8 T R1 R2 Out of 0 0 0 0 0 0 0 0 0 X 0 Hot air 0 0 X X 0 0 W 0 Conventional X X 0 0 X 0 0 0 X 0 grilling 0 0 X 0 X 0 y 0 0 W 0 Fast heating X 0 0 0 X x/o 0 X

Legend:

hl Bottom heat radiator h2 Top heat radiator h3 Grill heater h4 Hot air heater R Relay rapid heating T Quick heat button Th Oven thermostat S1 -S8 Oven selector switch

to Fig. 2

Switch logic oven

Operating mode S1 S2 S3 S4 S5 K H G T R1 R2 Out of 0 0 0 0 0 0 0 0 0 X 0 Hot air X 0 0 0 0 y 0 0 X 0 Conventional X X 0 0 X 0 0 0 X 0 grilling X 0 0 X 0 0 0 X 0 X 0 Fast heating X X 0 0 X 0 0 x/o 0 X

Legend:

h1 Bottom heat radiator h2 Top heat radiator h3 Grill heater h4 Hot air heater R Relay rapid heating T Quick heat button L Rapid heating display F Temperature sensor PT... BE electronic oven control S1 -S5 Oven selector switch K, H, G Oven coding switch

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Of course, the described embodiments of the invention can be modified in many ways without departing from the basic idea, in particular with regard to display options, type of actuating elements, etc.

Claims (4)

- &iacgr;&ogr; - Claims: 1. Electric oven with top heat and bottom heat elements, a grill integrated in the oven and a rapid heating circuit for simultaneous operation of the grill and bottom heat in the rapid heating phase and switching off the grill when the desired baking chamber temperature is reached, marked by a rapid heating relay for switching from grill/bottom heat element to top heat/bottom heat element and/or hot air element in the rapid heating circuit. 2. Oven according to claim 1,
marked by a switchover from grill to top heat element when the desired baking chamber temperature is reached. 3. Baking oven according to one of the preceding claims, characterized by a circuit with a rapid heating button for switching the rapid heating relay. - li - 4. Baking oven according to one of the preceding claims, characterized by a circuit with an optical display when the rapid heating is activated and/or in operation.