JP2014194908A - Heating cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem of an expensive price of a component caused because an inverter circuit is provided for each heat source thereby to make a substrate configuration complicated when two and more induction heating sources are provided in one product housing.SOLUTION: A heating cooker comprises: a plurality of load circuits each of which has a series circuit of a heating coil and a switch and which are connected in parallel with an output terminal of an inverter circuit for converting a DC current to a high-frequency current; and control means for controlling the inverter circuit and switches so as to output heating power set by operation input means. The control means outputs when the plurality of heating coils are electrically conducted at the same time by a setting input from operation input means, a driving signal having the maximum driving signal level of the inverter circuit which outputs set heating power and controls the heating coil which exceeds heating power set to be driven by the driving signal among the heating coils which are electrically conducted at the same time, so as to be disconnected from the output of the inverter circuit every predetermined period by the switch.

Description

  The present invention relates to a heating cooker having a plurality of heating coils.

  When there are two or more induction heating sources in one product casing, some conventional cooking devices have an inverter circuit that supplies a high-frequency current to the heating coil for each heating source. (For example, see Patent Document 1). Some conventional cooking devices supply high-frequency current to a plurality of heating coils by switching the connection of one inverter circuit in a time-sharing manner.

JP-A-8-213163 JP 2008-287923 A (FIG. 15)

In patent document 1, it has two heating coils and each has two inverter circuits for exclusive use. Therefore, there is a problem that the substrate is large, complicated, and expensive.
In Patent Document 2, the output of one inverter circuit is switched and connected to two heating coils in a time division manner. Therefore, the substrate can be made small and the price can be reduced. However, when two heating coils are used as separate heating ports, output is possible compared to the case where each heating coil is driven simultaneously. There was a problem that the maximum power was reduced.

  The cooking device according to the present invention has an inverter circuit that converts a direct current into a high-frequency current, and a series circuit of a switch and a heating coil that heats an object to be heated, connected in parallel to the output terminal of the inverter circuit. The load circuit, the operation input means for setting the thermal power to be output to the heating coil, and the control means for controlling the inverter circuit and the switch to output the thermal power set by the operation input means, the control means, When energizing a plurality of heating coils simultaneously by setting input from the operation input means, among the heating coils energized at the same time, the drive signal of the inverter circuit that outputs the set thermal power is output at the maximum. A heating coil that exceeds the set thermal power when driven by the drive signal is switched by a switch at predetermined intervals. It is obtained so as to control to disconnect the output of Nbata circuit.

  According to the present invention, a plurality of inverter circuits can be integrated, space saving and cost reduction can be realized, and even when a plurality of heating coils are energized simultaneously, they are driven at the same frequency. However, an interference sound due to the frequency difference of the induced current does not occur, and a cooking device having a large output power for all the heating ports in comparison with the time division driving can be obtained.

It is an appearance perspective view of a cooking-by-heating machine concerning an embodiment of the invention. It is a top view of the heating cooker which concerns on embodiment of this invention. It is a block block diagram of the heating cooker which concerns on embodiment of this invention. It is an inverter circuit structural example of the heating cooker which concerns on embodiment of this invention. It is a basic flowchart of the heating cooker which concerns on embodiment of this invention. It is a flowchart of IH heating cooking of the heating cooker which concerns on embodiment of this invention. It is a figure which shows an example of the relationship between the drive frequency of the inverter circuit of the heating cooker which concerns on embodiment of this invention, and output electric power. It is a figure which shows the drive pattern example of the inverter circuit and switch SW7 * SW8 of the heating cooker which concerns on embodiment of this invention. It is a figure which shows another drive pattern example of the inverter circuit and switch SW7 * SW8 of the heating cooker which concerns on embodiment of this invention. It is a figure which shows another drive pattern example of the inverter circuit and switch SW7 * SW8 of the heating cooker which concerns on embodiment of this invention. It is a figure which shows the example of the heating coil of a rice cooker. It is a figure which shows the example of the heating coil of the upper and lower heaters of an IH grill.

Embodiment.
FIG. 1 is a perspective view showing an appearance of a heating cooker 1 according to the present invention, and FIG. 2 is a top view of the heating cooker 1 according to the present invention. As shown in the figure, there are two induction heating units on the left and right, and the operation panel 13 on the right side of the front panel has a power switch 11, a left heating port 2L on the left side, and a right heating port 2R on the right side. It has dials 12L and 12R for adjusting the thermal power, and the user turns on the power switch 11 and operates the thermal power adjustment dials 12L and 12R according to the cooking situation to perform cooking. That is, the heating power adjustment at the time of induction heating in the left heating port 2L and the right heating port 2R can be performed by the heating power adjustment dials 12L and 12R. In addition, the rated power consumption (maximum power consumption) of this heating cooker 1 is 5800W.

  The upper side of the left heating port 2L and the right heating port 2R is covered with a top plate 14 formed of a heat-resistant tempered glass plate, and the space below the top plate serves as a heating source for the left and right heating ports 2L, 2R. Annular heating coils L1, L2 are installed. The periphery of the top plate 14 is covered with a frame-shaped metal frame 15, and is fixed to the upper surface of the main body case 1A by this frame.

  A central display, such as a liquid crystal display substrate as a display means for displaying set values of various cooking conditions, alarms and abnormality information, in the vicinity of the lower surface of the top plate 14 at the front upper portion of the cooking device 1 Similarly, the heating time of the left display panel 17L, the right display panel 17R, and the left heating port 2L including the liquid crystal display substrate for displaying the heating power value and the heating power level (strong, medium, weak, etc.) during induction heating, Left display unit 18L for displaying the oil temperature during cooking with liquid crystal characters or a plurality of light emitting diodes (light emitters), right display unit 18R for displaying the heating time of the right heating port 2L and the oil temperature during cooking with oil, In addition, an upper surface operation unit 19 for performing operations such as the start of the heating operation is provided.

  At the rear of the upper surface of the heating cooker 1, an air inlet 20 for taking air into a grill compartment 22 of the grill cooker 3 to be described later, and smoke or the like generated from the cooked food in the grill compartment 22. An exhaust port 21 is formed. The intake port 20 is for taking indoor air into the internal space of the heating cooker 1 with a blower (not shown), and a part of the taken air is used for cooling the heating coils L1 and L2. Then, the cooled air is discharged from the exhaust port 21 into the room. As shown in FIG. 3, a control circuit 32 that controls the overall operation of the cooking device 1 is provided in the internal space of the cooking device 1.

(Configuration of grill cooker 3)
Next, the configuration of the grill cooker 3 will be described with reference to FIGS. 1 and 2.
A grill cooker 3 is housed inside the lower left side of the heating cooker 1. The grill cooker 3 includes at least a grill door 26 that can be opened and closed on the left side of the front portion of the heating cooker 1, and a grill chamber that is a cooking space in which the front opening is opened and closed freely by the grill door 26. 26, a saucer 23 placed on the bottom of the grill cabinet 22, and a grill net 24 placed on the saucer 23 and on which an object 25 such as fish is placed. The grill door 21 is provided with a handle 26 </ b> A for a user to put a hand to open and close the grill door.

  Also, the exhaust duct for communicating the grill chamber 22 and the exhaust port 21 and exhausting the air taken in from the intake port 20 to the outside from the grill chamber 22 through the exhaust port 21 together with the smoke generated from the cooked food 25. (Not shown) is connected to the rear of the grill cabinet 22.

(Configuration of the upper surface operation unit 19)
Next, the configuration of the upper surface operation unit 19 will be described with reference to FIG.
In FIG. 2, the upper surface operation part 19 is arrange | positioned at the near side of the upper surface of the heating cooker 1 in the strip | belt shape long in the horizontal direction. That is, it is disposed on the front side of the frame-shaped metallic frame 15 on the nearer side than the front end of the top plate 14.

  The upper surface operation unit 19 includes, from the left side, a left heating port operation unit 27 for operating the heating operation of the left heating port 2L, a grill operation unit 29 for operating the grill heating operation, and the right heating port 2R. The right heating port operation unit 28 for operating the heating operation is provided.

Among these, the left heating port operation unit 27 includes a deep-fried food button 27a, a frying pan preheating 27b, and an on / off button 27c. The right heating port operation unit 28 includes a fried food button 28a, a frying pan preheating 28b, and an on / off button 28c. The grill operation unit 29 includes a grill menu button 29a, a start / stop button 29b, a left arrow button 29c, a right arrow button 29d, a time minus button 29e, and a time plus button 29f.
In addition, the kind and arrangement | positioning of each button which comprise the upper surface operation part 19 shown by FIG. 2 show an example, and are not limited to this.

(Control part of heating cooker 1)
In FIG. 3, 11 is a power switch that is opened and closed by a user located in the front operation unit 13, 31 is a power circuit to which electric energy is supplied via this power switch, and 32 is a predetermined constant pressure from this power circuit. It is a control circuit mainly composed of a microcomputer to which current is supplied. The microcomputer is composed of four parts: an input unit, an output unit, a storage unit, and a CPU (calculation control unit). In the storage unit, energization control programs corresponding to various cooking menus are stored in advance ( Stored).

  Reference numeral 33 denotes an inverter circuit for supplying a high-frequency current to the heating coils L1 and L2. The heating coils L1 and L2 are connected in a known resonance circuit to which resonance capacitors C1, C2, etc. are connected.

  Reference numeral 34 denotes a drive circuit for driving a plurality of radiant electric heaters, for example, sheathed heaters 34H, installed in the grill cabinet 22 of the grill cooker 3. The sheathed heater is installed horizontally, for example, near the ceiling and bottom of the inside of the grill cabinet 22, and is configured to heat the grill net 24 from above and below.

  Reference numeral 35 denotes a display unit drive circuit, which displays a central display panel 16 for displaying various cooking condition setting values, a left display unit 18L, a right display unit 18R, and heating power levels of the left and right heating ports 2L and 2R. The display panel 17L and the right display panel 17R are driven.

  37 is discharged from the grill warehouse 22 by heating an inlet portion of an exhaust duct (not shown) from the grill warehouse 22 to the exhaust outlet 21 or a catalyst (not shown) installed in the middle thereof. This is a catalyst heater for promoting the action of removing smoke, and is driven by the catalyst heater drive circuit 36 to heat the catalyst (not shown) to promote the oxidation-reduction action.

  Reference numeral 38 denotes a speech synthesizer that synthesizes electronically created speech, which informs the user of operation guidance, notification of occurrence of an abnormality, etc. from the speaker 39 each time.

  Reference numeral 40 denotes a temperature detection circuit. The temperature detection circuit 40 detects the temperature of the object N to be heated on the top plate 14 heated by the heating coils L1 and L2, the temperature of the top plate 14, the ambient temperature in the grill box 22, and the like. Temperature detection information is received from a plurality of temperature sensors (not shown), and the temperature detection result is sent to the control circuit 32. The temperature sensor (not shown) may be either a non-contact type such as an infrared sensor or a contact type such as a thermistor, and these are used alone or in combination.

(Configuration of inverter circuit of cooking device 1)
FIG. 4 shows a configuration example of the inverter circuit 33 of the heating cooker 1. (A) is a structural example of the inverter circuit of the conventional heating cooker, (b) is a structural example of the inverter circuit of the heating cooker which concerns on this invention.
In a heating cooker having two heating ports and having two heating coils, the conventional cooking device has an inverter circuit 33L having switching elements SW1 and SW2 for the heating coil L1, as shown in FIG. Whereas the inverter circuit 33R having the switching elements SW3 and SW4 is used for the heating coil L2, the heating cooker according to the present invention uses the inverter circuits 33L and 33R as a common inverter circuit 33 as shown in FIG. By covering this, space saving and cost reduction of the substrate can be realized.

Further, in the conventional cooking device 1, a high frequency current is supplied to the heating coil L1 by alternately switching SW1 and SW2 when the heating coil L1 is used, and SW3 and SW4 are alternately switched when the heating coil L2 is used. Thus, the heating coil L2 and the high-frequency current are supplied and the resonance with the resonance capacitor C2 is controlled. By using a circuit as shown in FIG. 4B, SW5 and SW6 are alternately switched. Thus, a high frequency current can be supplied to the heating coil L1 and the heating coil L2, and the total output of the two heating sources can be changed by changing the drive frequency or energization rate of SW5 and SW6. Moreover, the connection switching of the heating coil to be used is possible by switching ON / OFF of SW7 and SW8.

(Induction heating operation of the heating cooker 1)
Next, the induction heating operation of the heating cooker 1 according to the present embodiment will be described.
The flowchart shown in FIG. 5 shows the basic operation steps of the heating cooker 1. 1 to 3, the user operates the power switch 11 to turn on the power (step ST1). Then, power is applied to the control circuit 32, and the control circuit 32 obtains temperature information from the temperature detection circuit 40 and self-checks whether the main part of the cooker is at an abnormally high temperature (step ST2). ).

  The result of the self-check is determined (step ST3), and when an abnormality is found, the abnormality is notified (step ST4) and the heating is terminated. On the other hand, if no abnormality is found, the control circuit 32 activates the display unit drive circuit 35 to display on the central display panel 16 that cooking can be started, and controls the voice synthesizer 38 to control the central display panel 16. The content similar to the content displayed in is notified by voice (step ST5).

  After that, the central display panel 16 displays characters for urging the user to place the heated object N such as a metal pan on the heating ports 2L, 2R that the user wants to use (step ST6). The heating port to be selected is determined (step ST7). Here, when the user presses the on / off button 27c in the left heating port operation unit 27, the left first heating port 2L is selected, and the on / off button in the right heating port operation unit 28 is selected. When 28c is pressed, the second heating port 2R on the right side is selected. In that case, the process proceeds to the step of selecting the induction heating menu and setting the heating power. In this step, for example, if the fried food button 27a is pressed, fried food cooking is selected, and if the preheat button is pressed, preheated cooking such as a frying pan is selected. Further, the user sets the heating power by rotating the heating power adjustment dials 12L and 12R of the left and right heating ports installed in the front operation unit 13 of the main body case 1A (step ST8). The control circuit 32 performs display on the left and right display panels 17L and 17R and the left and right display sections 18L and 18R according to the selected induction heating menu and set heating power, and executes IH cooking (step ST9). The details are shown in the flowchart of FIG. 6 and will be described later.

  On the other hand, when the user presses the on / off button 29b in the center in step ST7, it means that the grill cooker 3 using a heating source of electric radiant heat is selected, and roaster cooking, grill cooking or oven cooking is performed. It progresses to the step (step ST10) which selects either. Thereafter, roaster cooking (step ST11A), grill heating cooking (step ST11B), and oven heating cooking (step ST11C) are performed in accordance with the selection input, and the heating state is displayed on the central display panel 16.

  After the cooking, the user can end the induction heating operation by pressing the on / off buttons 27c and 28c again. If the on / off button 29b is pressed, the heating operation by the electric radiant heat of the grill cooker 3 can be terminated (step ST12).

FIG. 6 is a flowchart showing a control process for IH heating cooking of the left and right heating ports 2L, 2R. When a new heating start of the left heating port 2L or the right heating port 2R is requested, when the other heating port is heating, the drive of the inverter circuit 33 is stopped (step ST9-1), and the heating start is started. The requested heating port is discriminated (step ST9-2), and if it is the left heating port 2L, the switch SW7 is turned on to connect the heating coil L1 to the output of the inverter circuit 33 (step ST9-3). If the heating port requested to start heating is the right heating port 2R, the switch SW8 is turned on to connect the heating coil L2 to the output of the inverter circuit 33 (step ST9-4).

Next, the inverter circuit 33 is driven with a load determination drive signal (low output level) to determine whether or not an appropriate pan is placed on each heating coil, and an unsuitable pan such as an aluminum pan is placed. If it is, the corresponding heating coil is disconnected from the output of the inverter circuit by turning off the switch SW7 or SW8 (step ST9-5). When there is a heating coil on which an appropriate pan is placed, the drive frequency of the inverter circuit 33 and the switches SW7 and SW8 of the load circuit are set so as to be the set heating power of the corresponding heating port 2 set from the operation unit. Is controlled to adjust the heating output (step ST9-6).

FIG. 7 shows an example of the relationship between the drive frequency of the inverter circuit and the output power when a pan is placed above the heating coil L1 and the heating coil L2 and heating is performed at the same time. The relationship between the drive frequency and the output power to each heating coil varies depending on the conditions such as the material, size, position, and temperature of the placed pan, but in the following description, the relationship shown in FIG. 7 is maintained. And

Note that, under the load condition of FIG. 7, the lower limit value of the drive frequency of the inverter circuit is determined from the limit of the current that can be passed through the switching elements SW5 and SW6 of the inverter circuit 33 (the output current limit value of the inverter circuit). 25 kHz when both L1 and heating coil L2 are connected to the inverter circuit output, 24 kHz when only heating coil L1 is connected to the inverter circuit output, 21 when only heating coil L2 is connected to the inverter circuit output It shall be 5 kHz.

(Left heating port: 1.5 kW, Right heating port: 1.0 kW)
Under the load conditions of FIG. 7, the drive pattern of the drive of the inverter circuit 33 and the on / off control of the heating coil series switches SW7 and SW8 when outputting 1.5 kW to the left heating port 2L and 1.0 kW to the right heating port 2R An example is shown in FIG. In the present embodiment, the control is repeated every 6 seconds. When the inverter circuit 33 is driven at 26 kHz, 2.0 kW can be output from the left heating port 2L and 1.0 kW can be output from the right heating port 2R as shown in FIG. Therefore, in order to make the left heating port 2L output 1.5 kW, heating output (2.5 kW) is performed for 4.5 seconds out of 6 seconds, and the switch is turned off for 1.5 seconds to stop the heating output. .
Heating output of the left heating port: 2.0kW × 4.5 / 6 + 0kW × 1.5 / 6 = 1.5kW
Heating output of the right heating port: 1.0 kW x 6/6 = 1.0 kW

(Left heating port: 2.5 kW, right heating port: 1.0 kW)
FIG. 9 shows an example of driving the inverter circuit 33 and on / off control of the heating coil series switches SW7 and SW8 when outputting 2.5 kW to the left heating port 2L and 1.0 kW to the right heating port 2R under the same conditions. Show. When the inverter circuit 33 is driven at 25 kHz, the cooking device according to the present embodiment can output 2.5 kW at the left heating port 2L and 1.2 kW at the right heating port 2R, as shown in FIG. Therefore, the inverter circuit 33 is driven at 25 kHz, the SW7 is kept on, and the SW8 is switched on and off (6-second cycle: on 5 seconds, off 1 second).
Heating output of left heating port: 2.5kW × 6/6 = 2.5kW
Heating output from the right heating port: 1.2 kW x 5/6 + 0 kW x 1/6 = 1.0 kW

(Left heating port: 1.5 kW, Right heating port: 1.5 kW)
FIG. 10 shows an example of driving the inverter circuit 33 and ON / OFF control of the heating coil series switches SW7 and SW8 when 1.5 kW is output to the left heating port 2L and 1.5 kW is output to the right heating port 2R under the same conditions. Show. In the present embodiment, the lower limit value of the drive frequency of the inverter circuit 33 when both the heating coil L1 and the heating coil L2 are connected is 25 kHz, 2.5 kW at the left heating port 2L, and 1. 2 kW can be output. Therefore, out of the 6-second period, the inverter circuit is driven at 25 kHz for 3.6 seconds and SW7 and SW8 are turned on, and SW7 is turned off and SW8 is turned on for 2.4 seconds, and the right heating port 2R is turned on. Drive at a drive frequency (23 kHz) at an output of 1.95 kW.
Heat output of the left heating port: 2.5 kW x 3.6 / 6 + 0 W x 2.4 / 6 = 1.5 kW
Heating output of the right heating port: 1.2 kW × 3.6 / 6 + 1.95 kW × 2.4 / 6 = 1.5 kW

In the above embodiment, the case where the drive frequency of the inverter circuit is limited by the output current limit value of the inverter circuit has been described. However, it is possible to flow through the switching elements (SW7, SW8) of the individual load circuits. The same applies to the case where the drive frequency of the inverter circuit is limited based on the limit value of the current (the output current limit value of the load circuit) or the limit of the power value that can be output to each heating port.

Further, in the present embodiment, as shown in FIG. 7, the example of controlling the driving frequency of the switching elements SW5 and SW6 in order to adjust the output of the inverter circuit 33 is shown, but the energization of the switching elements SW5 and SW6 is shown. The rate may be controlled. Since a large current for two heating ports flows through SW5 and SW6, at least one of them uses a switching element of a wide band gap semiconductor made of SiC, GaN, diamond, or the like. If a device with a small sum is used, the loss in the switching element can be suppressed, and the heating efficiency can be improved. On the other hand, since SW7 and SW8 do not require high-speed switching, switching elements such as bidirectional thyristors and relays may be used. In addition, when switching on / off of SW7 and SW8, the loss which arises in SW7 and SW8 can be suppressed by performing at the timing when the load current which flows into a heating coil is zero.

In addition, when the heat dissipation FIN of the switching element is provided individually, by placing at least one of the heat dissipation FIN of SW5 and SW6 on the windward side of the heat dissipation FIN of SW7 and SW8, loss due to a large current is large, and thermal destruction It is possible to protect a switching element having a high possibility.

In the above embodiment, an example is shown in which the present invention is applied to a plurality of heating coils arranged at a plurality of heating ports. However, the present invention may be applied to an inner heating coil and an outer heating coil of one heating port. The present invention may also be applied to a rice cooker having L3 and L4 (FIG. 11) and a plurality of heating coils L5 and L6 for induction heating the upper and lower heaters of the IH grill (FIG. 12).

  Moreover, although the heating cooker which has two heating coils was shown in the said embodiment, the same heating control can be performed even if it has three or more heating coils.

DESCRIPTION OF SYMBOLS 1 Heating cooker, 1A Main body case 2 Heating opening, 2L Left heating opening, 2R Right heating opening 3 Grill cooking appliance 11 Power switch 12L Left heating power adjustment dial, 12R Right heating power adjustment dial 13 Front operation part 14 Top plate 16 Central display panel 17L Left display panel, 17R Right display panel 18L Left display unit, 18R Right display unit 19 Upper surface operation unit 27 Left heating port operation unit 28 Right heating port operation unit 29 Grill operation unit 32 Control circuit 33 Inverter circuit 35 Display unit Drive circuit C1 Left resonance capacitor, C2 Right resonance capacitor L1 Left heating coil, L2 Right heating coil L3 Rice cooker outer heating coil, L4 Rice cooker inner heating coil L5 IH grill upper heater heating coil, L6 IH grill lower heater heating coil SW1-SW8 switching element

Claims (6)

An inverter circuit for converting a direct current into a high frequency current;
At least two load circuits having a series circuit of a switch and a heating coil for heating an object to be heated, connected in parallel to the output terminal of the inverter circuit;
Operation input means for setting the heating power to be output to the heating coil;
Control means for controlling the inverter circuit and the switch to output the thermal power set by the operation input means,
When the control means energizes the plurality of heating coils simultaneously by setting input from the operation input means, the drive signal level for outputting the set heating power among the heating coils energized simultaneously is maximum. And the heating coil that exceeds the set thermal power when driven by the drive signal is separated from the output of the inverter circuit by the switch at predetermined intervals. .   The cooking device according to claim 1, wherein the control means controls the drive signal level of the inverter circuit so as not to exceed an output current limit value of the inverter circuit.   The control means controls the drive signal level of the inverter circuit so as not to exceed an output power limit value or an output current limit value of the load circuit to be energized. Cooking device. Comprising current detection means for detecting the current of the load circuit;
The cooking device according to any one of claims 1 to 3, wherein the control circuit turns off the switch at a timing when the load current detected by the current detection means becomes zero.   The cooking device according to any one of claims 1 to 4, wherein a wide band gap semiconductor is used for a switching element constituting the inverter circuit.   6. The cooking device according to claim 5, wherein the wide band gap semiconductor element is made of SiC, GaN, or diamond.

Images