DE2036654A1 - Automatic program control for microwave ovens - Google Patents

Description

Purely the preparation of food in the oven is when using microwave technology, alone or in conjunction with thermal heating! the right schedule or workflow of decisive importance know dishes, e.g. B. cakes and roasts should be closed at this point the pores on the outer surface are closed at a fairly early stage, for example by heating, before the treatment begins by microwaves} it can also be two-way, to continue the thermal heating by microwaves during and / or after a certain cooking time.

Proper workflow is also important for defrosting and cooking frozen food, which is complete at the beginning are interspersed with ice crystals. If you dtn time-

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If you want to avoid the consuming process of thawing frozen food at room temperature, you can do it for a short time irradiate with microwaves, whereby the ice crystals by the heat generated in this way during a following The booing period can melt? then you can cook the defrosted food in the normal way using microwaves. In a microwave oven which also includes an electric heater for conventional thermal heating, can food be thawed by selectively turning on the electric heater before using microwave energy. In the microwave ovens known to date, a work program control of the microwave energy, alone or in Connection with thermal energy, can only be carried out by placing selector switches and buttons according to an instruction manual or after trying the right times and turns off.

Figure 1 is a combined schematic and block diagram representation an oven and a system according to the invention for the automatic control of the oven for operation with microwave energy and / or thermal energy «

Figure 2 is a diagrammatic representation of a microwave oven with control buttons and time dial, which are contained in the program input device of the system from FIG.

Figure 3 is a combined schematic and block diagram representation of the program input device and one

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Sequence control networks for the oven from Figure 2.

Piiur 4a-4d are graphical representations of various Working props for the oven from FIG. 2.

Figure 5 shows as a block diagram the program input £. & Advises ir Torn, a card reader and the timer and Helicopter networks that are programmed in such a way that they and Aussci: old times and the order for conventional Control heating energy and microwave energy.

Fifur 6 is. a block diagram of the invention Plant, "in which one and the same elements are used are »heat energy and microwave energy in the oven to radiate.

• Hgur 1 shows the interior 10 of an oven, in your sicli are the electrical heating elements 12 and 14, which can be connected to a voltage source 16 via a switching network 18 in order to heat one or both elements. The antenna elements 20 and 22, which are connected to the output probes 24 and 26 of a waveguide feed, are also located in the interior 10 .28 are connected. A magnetron 30 is mounted so that its input probe Il microwave energy feed 28 for operating antenna elements 20 and 22, which feeds the microwave energy into interior 10 of the oven, - ^ ine microwave voltage control circuit 32 is connected to the magnetron and may contain controls to selectively operate the magnetron on a operate from two different energy levels, e.g. B.

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at full power or half power. . · · '-'-.

The heating switching network 18 and the microwave voltage control circuit 32 are controlled by a sequence control network 40 operated. The sequencer network 40 includes suitable timing devices and relays for operating the switching network 18 and the control circuit 32 to selectively to operate the heating elements 12, 14 and the antenna elements 20, 22 in a certain order. The operation of the follow-up control network 40 iBt according to the operation of the program input device 42 programmed.

The program input device 42 'contains any suitable Devices in the control network 40 a desired order for switching on and off conventional Set up heat energy and microwave energy and select the total working time. For example, have a microwave oven 44 (Figure 2) a number of button switches 45-49, which are used to preselect a special operation, in Door-to-door example "warming", "baking", "roasting", "roasting" and "grilling". In this case, pressing one of these buttons starts a specific work program in the control network 40 selected * according to which microwave and / or thermal energy is radiated into the oven in a certain order. A * Rotary knob 50 serves as a time selector switch with which the total number for a given work program can be set depending on the type of food in the oven.

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,. Figure 3 shows the sequencer network 40, the ' a timer network 52, relay circuits 54 between the • Timer network 52 and the heater switch network and relay circuits 56 contains, which is between the timer network. factory and the microwave voltage control circuit. ■ Each of the switch buttons 45-49 can, for example, corresponding Activate the timer in the network 52 in order to control the relay circuits 54 which are used to operate the heating switching network serve, whereby one or both heating elements are connected to the voltage source, and on the other hand to control the relay circuits 56 which form the microwave voltage control circuit actuate, which operates the magnetron at the desired energy level. The timers can be motor-operated switches that use appropriate relay branches to carry out the desired mode of operation are operated, whereby the timer switch 50 can determine the speed of the timer motors, whereby the program duration is selected for a given quantity or type of food.

Figures 4a-4d are graphic representations of various programs, - the switches 45-48 to be selected. Figure 4a shows the operation. "Warming", which is selected by pressing button 45 and yourself suitable for warming finished dishes or defrosting frozen food. In this case it exists in the timer network 5 * 2 and work program set up in the relay circuits 54

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in that the oven is first heated to a certain temperature, indicated are 65 ⁰ C (150 ⁰ F), this temperature being scanned by a suitable sensor in the oven. In FIG. 1, a thermostat 58 is provided for this purpose, which is connected to the heating switching network 18 and the sequence control circuit 40. In Figure 3, the thermostat can be connected to the timer network 52 which is suitably designed, e.g. B. by latching relays to turn on the timers when the oven has reached the temperature of 65 ⁰ C (150 ⁰ F). For this first heating of the oven, the heating switching network 18 is operated in one embodiment in such a way that only one of the heating elements 12, 14 is connected to the voltage source 16.

When the oven ^{temperature has reached 65 0} C (150 ⁰ F), the microwave voltage control circuit is operated so that microwave energy is radiated from the magnetron 30 into the oven at certain time intervals. In FIG. 4a, each heating period is 2/10 (two tenths) of the total time selected, and the intervals between these periods are also 2/10 of the total time. In one embodiment, the associated clock timers and relay circuits operate the microwave voltage control circuit so that the magnetron operates at half power. For the longest possible life of the magnetron, the heating transformer of the magnetron voltage source can remain switched on, or it can be switched off while microwave energy is in use

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is generated, and in the intervals between such periods "i will be turned back on to the correct cathode temperature to ensure! as often as the power transformer with the anode is connected.

As FIG. 4a also shows, thermal energy is given off to the oven at certain intervals. The heating switching network is controlled so that the heating for certain periods with a duration of 1/20 of the total time is switched on, the interval between the heating periods 1/10 of the total time.

When frozen food according to that shown in Figure 4a " Both types of energy are at work only intermittently on the frozen food, so that the heat generated inside the iron is retained during the breaks Can distribute evenly · By suitable selection of the total time of the working program space one reaches that all single crystals are completely melted at the end of the program

A conventional alarm or display device switches on after the end of the work program and thereby indicates the end of the program. During the warm-up program, the display device shows that the food can be removed from the oven and served. I ^{1 For} pre-cooked frozen food, the display device says that the food has been thawed, whereupon the warm-up program can be run through again by pressing the appropriate button until the display device displays the program when the program is finished.

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that the food can be taken out and served / For uncooked frozen food, the display device shows at the end of the program that the food is thawed and now can be cooked by either pressing the button for "Bake", for baking a cake, or with meat the button for "Roast" or "Grilling" is printed, etc.

In connection with FIG. 4a it should be mentioned that pulsed thermal energy and pulsed microwave energy are used here is used. If desired, a program can of course also be set up, through which the food alone be warmed up or thawed by one or the other form of energy. For example, the timer and Relay circuits in different embodiments alternately or simultaneously both heating elements for shorter ones Heating periods and longer intermediate intervals with the voltage source, the total time being chosen so that the desired Warming up or defrosting of the food is achieved. On the other hand, the microwave voltage control circuit can be so regulated be that the magnetron works at full power for shorter periods with longer intervals in between, in order to thereby to achieve the desired warming up or thawing.

With the present invention, food can be warmed up or thawed very quickly. By turning on the or the heating elements for periods of 10 seconds with 20 second intervals and by operating the magnetron in periods of 5 seconds with intermediate intervals of 25 seconds

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A portion of frozen raw meat can be cut into three Thaw minutes. If built up solely by thermal energy • is to be, the operation of the element or elements is preferably carried out with longer intermediate intervals, e.g. B. 2 minutes "at, a total time of 15 minutes, the heating elements being switched on alternately in periods of 10 seconds. The magnetron is used to thaw by microwave energy alone for longer periods, e.g. B. 10 seconds, operated at 15 second intervals for a total of 7 minutes.

The baking program shown in Figure 4b, which can be set by the button switch 46, begins with the heating of the oven by thermal energy up to a temperature of z. B. 160-177 ⁰ O (320-350 ⁰ P), which is then maintained. For this purpose, a separate temperature sensor is connected to the sequence control network 40, which initiates the "baking" program. For this work program, the timer and associated relay positions control the microwave voltage control circuit so that the magnetron is in operation during the second half of the work program;

For the "frying" (Figure 4c) wird'der oven to a higher temperature, such, for example 190-205 ⁰ C (375-400 ⁰ F) heated and maintained at that temperature, where the microwave energy during the last 7 / 10 of the working period is switched on. In the "roasting" program (FIG. 4d), too, thermal energy is supplied during the entire operation, the temperature after heating in one

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The range of 232-246 ⁰ C (450-475 ⁰ P) is maintained, but with microwave energy being supplied during the first 7/10 of the total period, i. immediately after reaching the desired oven temperature,

For grilling, only the upper heating element 12 is connected to the voltage source when the button switch 49 is pressed will. In this case, the food is pushed in on a grate just below the heating element 12.

The invention encompasses any suitable program input and sequence control circuit with which microwave energy and / or thermal energy can be released automatically into the interior of an oven in the desired sequence. As FIG. 5 shows, the program input device can contain a card reader 42 which outputs data signals or pulses to the timer and relay circuits 66, 68 which are connected to the heating control circuit and the magnetron voltage control circuit. The card reader 42 * f can be in any design used, depending on the type of cards used and the type of information recorded on the map data. For example, magnetic card readers for Llagnetkarten, electric or photoelectric readers for punched cards and readers for scanning protrusions or raised markings are mentioned here.

stanchions on the cards, which are arranged and dimensioned are that thereby the desired microwave and / or thermal heating periods can be programmed. Also includes the invention any suitable device for a desired one

0Ö988S / 1S23.

Timing using electrical, electromechanical or neurological methods. With electrical time delay devices the invention includes the use of integrated circuits as well as digital methods, whereby time intervals have it adjusted.

The above description was based on a Likrov / ellenbaCiCofen with separate dispensing devices of microwave energy and thermal energy; according to the "present In accordance with the invention, however, combined elements can also be used to deliver both forms of energy. Like figure 6 shows, the oven interior 10 contains folded elements (Calrod elements) 70, 72, the ends of which are connected to the heating switching network 18 and the middle sections of which are connected to the output probes 24, 26 of the waveguide feed 28. These Elements act as antennas with advancing waves and radiate microwave energy into the interior of the oven, when they are excited via the waveguide supply, whereby they can be heated at the same time via a power source and give off thermal energy to the oven. The PoIgest euerungsnet'zwerk 40 controls the operation of the heating switching network 18 and the magnetron 30, as already described in connection with FIG.

In Figures 1 and 2 devices are shown that cause air circulation in the oven interior. An air cooling source 60, the motor let connected to the sequence control network 40 is mounted so! that they are one

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cooling air flow through the magnetron into the waveguide; ftifirung blows, and the oven 44 (Figure 2) contains one Hehe of openings 62 on its top. According to the invention Such a cooling air flow through the oven is used to support the warming and thawing process of food and prevents spoilage of uncooked frozen food after defrosting. When defrosting or defrosting, the Air entering the furnace from the waveguide feeds provides rapid cooling of the switched-off heating elements. Through this lets you specify the end of each heating season more precisely, so that

the subsequent rest interval achieves a higher level of efficiency.

When defrosting uncooked frozen food, the cooling air flow is also available after the program has ended be maintained. In this coat, the air flow cools the surface of the food sufficiently to prevent it from spoiling Food for a reasonable period of time after defrosting, e.g. B. «an hour to prevent, until then the food is as requested be cooked, e.g. B. by Programoiv / ehl for "baking". the end For this reason it is advisable to have separate programs for warming and defrosting, i.e. separate buttons or separate cards with the data for the warm-up program and are recorded for the defrost program. In In this case, the sequence control network operates the air

jr

cooling throughout the warm-up program while the Air cooling when defrosting after the end of the program

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■ certain time, ζ. B. one hour, is maintained. '

In another application example of the invention, a relationship can be established between the food to be cooked by microwave energy and / or thermal energy and the temperature of the food. For this purpose, the temperature sensors described above can consist of probes that are inserted into the food. Such a probe can be used as a control element in the same way as an oven thermostat. Such temperature sensors can be simple detectors or devices that can generate signals that are used as additional control signals to switch the infrared and microwave radiators on or off.

It should be mentioned that the invention can be used both for microwave ovens which use radiating antennas provided in the Baok oven and for ovens in which the microwave energy is introduced through openings in a waveguide wall. The invention is also suitable for such ovens which contain any suitable stirring mechanism.

Finally, an essential feature of the invention should be mentioned, namely the low power consumption that can be achieved as a result. In the case of periodic operation using microwave energy and / or thermal energy , the power consumption is only a fraction of the power required for continuous operation of the Hagnetron or the heating elements

_v would be required. This can be done in certain geographical areas

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and under certain circumstances τοη be meaning, z. B. in mobile systems, such as caravans, airplanes and ships, where the supply of electrical and electronic equipment in stock is limited. Under such circumstances, an oven according to the present invention by Wunech only by periodically supplied microwave energy or by only periodically supplied heat energy or by periodic supply of both forms of energy be operated f, but not both forms of energy are simultaneously turned on.

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Claims (7)

Patent pending Automatic program control for microwave ovens. PATENT CLAIMS 1 1. J microwave oven, characterized by devices (20-28, 30, 32) for introducing microwave energy into the oven; Control devices (40) coupled to the energy introduction device for controlling the operation thereof, the control device including selection devices (68; 45-49) which can be selectively adjusted to one of a plurality of operational sequences of the energy introduction device, the level of the in energy introduced into the oven is changed more than twice; Means (42) for programming the control device including means (52) for adjusting dial 68 to suit its settings and for automatic operation 009885/1623 to control the energy introduction device (30) so that da3 ' The level of energy introduced into the oven is changed according to the order in which the setting selected. corresponds to the selection device} and devices (50), which with the programming device (42) and control device (40) and serve to selectively adjust the duration of the duty cycle during which the control device performs the energy level changes of the energy introducer according to the selected setting. 2. Microwave oven according to claim 1, characterized by devices (18j 12, 14) for thermal heating the oven interior; wherein the control device (40) includes selection devices (66) which are selectively to one of several switch-on and switch-off sequences of the thermal heating device can be set j devices within the Programming device (42) to simultaneously set both dialing devices (66, 68) to one of several combined settings and to automatically turn on and off the energy introduction device and the thermal heater according to the selected combined setting} and devices (50) associated with the programming device (42) and control device (40) are related and serve to selectively adjust the duration of the working cycle, during which the control device stops the operation of the energy introduction device and the thermal heater * according to the selected combined setting. 009885/1823 3. Microwave oven according to claim 2, characterized in that that the heating device contains a pair of heating elements (12, 14) which are separated from one another so that - Food can be introduced between the elements, the programming and control device (42, 40, 18) ensures that either each heating element is operated alone or both heating elements are operated together. 4. Microwave Baok oven according to claim 3, characterized in that that the programming and control device ensures that both heating elements simultaneously or alternately operate. 5. Microwave Baok oven according to claim 2, characterized by devices (60) for generating a cooling Iiuftstroms in the oven, wherein the programming and control device (42, 40) ensures that the Iiuftstrom-Eraeugungavorricbtung after completion of a certain, selectively aufeatellttu work cycle remains in operation for a certain period of time. 6. Microwave oven according to claim 3 *, characterized in that that the Energieeinführungvorriohtung a magnetron (30), a waveguide feed (28) between the magnetron and the oven and a microwave voltage control circuit (32), which is between the control device (40) and the magnetron is located and which serves to the magnetron · ■ ■ 009885/1623 operate at 'different power levels, with the Programming and control device (42, 40) for controlling the Circuit (32) is used to control the magnetron at a given power level or at all different power levels to operate within selectively established work cycles. 7. microwave oven according to claim 6, characterized in that the heating elements contain central sections (70, 72), which are coupled to the waveguide feed (28) and work ala antennas that the microwave energy in the Blast oven; with a voltage source (16) and a switching device (18) between the voltage source and the Heating elements, wherein the programming and control device is used to operate the switching device (18) to either tines dtr heating elements or both heating elements to be connected to the voltage source. 00988S / 1623