JP6830078B2 - Induction heating cooker - Google Patents

Description

The present invention relates to an induction heating cooker of a type including a heating means for heating an object to be heated by induction heating and driving the heating means by an inverter circuit.

In the conventional induction heating cooker, a pot to be heated is placed on a plate arranged on the upper surface of the main body, and the pot is heated by a heating coil provided in the main body below the plate, and is an inverter circuit. By adjusting the current flowing through the heating coil, the heating output is adjusted.

In the inverter circuit, the switching element is attached to a heat sink and cooled, and a temperature detecting means for detecting the temperature of the IGBT is provided in the vicinity of the switching element, and the IGBT drive circuit is controlled according to the temperature detected by the temperature detecting means to control an arbitrary temperature. When it exceeds, the output at the time of heating is lowered, and then, when there is a further temperature rise, the output is stopped (Patent Document 1).

Japanese Unexamined Patent Publication No. 2004-55277

The IGBT, which is a switching element for energizing the heating coil with a high-frequency current, generates heat during operation, but if the connection with the heating coil is poor due to the state (material or deformation) of the bottom of the pot, which is the object to be heated, the heat generation increases. The heat may cause a failure. Therefore, by stopping the heating or controlling the output by the detection temperature in order to prevent the switching element from failing due to heat, the user has become difficult to use as the thermal power decreases and the thermal power stops.

The induction heating cooker of the present invention has been made to solve the above problems, and includes a heating coil that heats an object to be heated by induction heating, an IGBT that supplies power to the heating coil, and an IGBT of the IGBT. The control includes a temperature detection element for detecting a temperature and a control unit that controls the IGBT according to the detection temperature of the temperature detection element to adjust the heating power of the heating coil to the object to be heated. When the temperature detected by the temperature detecting element reaches the set temperature Ta, the thermal power is lowered, and when the temperature detected by the temperature detecting element reaches the set temperature Tb set higher than the set temperature Ta, the unit is described. In addition to reducing the heating power, the pot being used issues the first notification that is inappropriate for heating, and when the number of times of cooking that issues the first notification reaches a predetermined number, the second notification that the pot is replaced is urged . It is for notifying.

According to the present invention, the number of times of cooking with reduced heat is measured, the number of times of cooking with reduced heat is set, and the number of cooks with reduced heat is notified when the number of cooks is reduced to a certain number. Even if there is no extra pot, it is possible to eliminate the discomfort to the user by preventing frequent notifications for each cooking.

It is a perspective view of the state in which the induction heating cooker of this invention is housed in a system kitchen. It is explanatory drawing which shows the state which the plate of the induction heating cooker was removed. It is a main sectional view seen from the side of the induction heating cooker. It is explanatory drawing of the upper surface operation part of the induction heating cooker. It is explanatory drawing of the circuit of the inverter part of the induction heating cooker.

Hereinafter, examples of the present invention will be described with reference to the above drawings. In addition to the built-in type that fits into the kitchen, this embodiment may be a stationary type cooking cooker that is placed in the kitchen.

The main body 2 of the cooking cooker is incorporated by dropping it from the upper surface of the system kitchen 1 and installing it.

The pot of the object to be cooked (not shown) is made of heat-resistant glass or the like arranged on the upper surface of the main body 2 and can be cooked by being placed on the mounting portion 6 of the plate 3 that transmits light. ..

In the mounting portion 6, the mounting portion right 6a and the mounting portion left 6b are arranged in front of the upper surface of the plate 3 on the upper surface of the main body 2, and the mounting portion 6 is placed in the back (center rear portion) between these both mounting portions 6a and 6b. The central part 6c is arranged. A heating coil unit 25, which will be described later, is installed under each of the mounting portions 6 with the plate 3 in between. The arrangement is such that the heating coil unit right 25a is below the mounting portion right 6, the heating coil unit left 25b is below the mounting portion left 6b, and the heating coil unit center 25c is below the mounting portion center 6c. It is provided.

A frame 14 is provided on the peripheral end surface of the plate 3 to protect the plate 3. The frame 14 includes a frame front 14a attached to the front upper edge of the plate 3, a frame rear 14b attached to the rear upper edge of the plate 3, 14c attached to the right upper edge, and a frame attached to the left upper edge. It is composed of the left 14d.

Inside the main body 2, electronic components constituting a heating coil unit 25 which is a heat generating member and a control circuit to be described later are provided, and behind the heating coil unit 25 and the control circuit, these are for cooling. A blower fan 20, an intake port 7 for sucking air from the outside of the main body 2, and an exhaust port 8 for discharging the cooled exhaust are provided.

The air sucked through the intake port 7 is discharged to the outside of the main body 2 from the exhaust port 8 after cooling the heating coil unit 25 and electronic components that generate heat inside the main body 2.

Further, on the left side of the main body 2, a roaster 4 for baking fish, pizza, or the like is provided.

Next, a heating coil, which is a heating means for heating the pot of the object to be heated, will be described.

The heating coil unit 25 for heating a pan (not shown) is composed of a heating coil 13, a coil base 24, and ferrite (not shown). Then, a certain gap is provided between the plate 3 and the heating coil unit 25, and a part of the cooling air from the blower fan 20 is allowed to flow through this gap to cool the back surface of the plate 3 and the heating coil unit 25. doing.

A litz wire is used for the winding of the heating coil 13 in order to suppress the skin effect. A voltage of several tens of kHz and several hundreds of volts is applied to the heating coil 13 from the inverter boards (left and right inverter boards 18 and central inverter board 17) described later in order to heat the cooking pot (not shown).

In the coil base 24, the heating coil 13 is fixed from below, and ferrite (not shown) is embedded substantially radially.

Further, a temperature detecting element 21 for detecting the temperature of the pot during automatic cooking or the like is attached to a space substantially in the center of the heating coil 13.

Next, cooling of the heating coil 13 and the inverter substrate will be described.

The inverter board is composed of a left and right inverter board 18 equipped with an inverter circuit for driving the left and right heating coils 13a and 13b, and a central inverter board 17 for driving the center 13c of the heating coil.

The left and right inverter boards 18 and the central inverter board 17 are arranged in the board case 26, and the heat generated by the electronic components is efficiently exchanged with the cooling air from the blower fan 20 to lower the temperature. Is provided.

The cooling outside air sucked from the intake port 7 by the blower fan 20 flows through the board case 26, and takes heat from the left and right inverter boards 18, the central inverter board 17, and the electronic components of the control board 19 on which the control circuit is mounted. After that, it is blown out from the substrate case 26 to cool each heating coil 13, other parts in the main body 2, and the back surface of the plate 3, and then discharged to the outside from the exhaust port 8.

The substrate case 26 is installed below the heating coil unit right 25a opposite to the heating coil unit left 25b where the roaster 4 is installed. In this embodiment, it is installed on the lower side of the heating coil unit right 25a, and by arranging the left and right inverter boards 18 and the central inverter board 17 inside, the radiant heat from the heating coil 13 and the roaster 4 is blocked during cooking, and inside. An air passage through which the cooling air passes is formed so that the cooling air can be efficiently distributed.

Next, the operation unit and the display unit will be described.

The main power switch 9d is composed of a push button, and each time the main power switch 9d is pressed, the power is switched between a power on state and a stop state.

The upper surface operation unit 9 is composed of touch keys that detect changes in the capacitance type. Specifically, the lower part of the plate 3 is composed of an operation board 12 provided with an electrode 36, which will be described later, for detecting a change in capacitance when a finger is touched.

The key parts are the off / start key 48, 56, 61, the low heat key 49a, 57a, the low heat key 49b, 57b, the medium heat key 49c, 57c, the high heat key 49d, 57d, and the menu key provided on the upper surface operation unit 9. 52, 60, 64 and the like are shown.

The upper surface operating portion 9 is provided on the front side of the plate 3, and corresponds to the mounting portion right 6a, the mounting portion center 6c, and the mounting portion left 6b, from the right, the upper surface operating portion right 9a, the upper surface operating portion center 9c, The left side 9b of the upper surface operation unit is arranged. An upper surface display unit 10 including an upper surface display unit right 10a, an upper surface display unit center 10c, and an upper surface display unit left 10b is provided on the upper side of each upper surface operation unit 9.

The upper surface display unit 10 is held by the plate 3 by the display holder 32, and a display board 33 including a drive circuit for displaying characters or the like is fixed to the central portion in the central portion. A liquid crystal display element and an LED element are arranged on the upper surface display unit to display the set thermal power level and the setting menu. Further, inside the product, a voice synthesis output function is implemented as a notification means 87 as a key capture sound, voice guidance on how to use the device, and a voice announcement for notifying an abnormality.

Next, each key portion of the upper surface operation unit 9 (typically, the upper surface operation unit right 9a) for setting the heating conditions for the pan will be described.

Reference numeral 48 denotes an off / start key for starting or stopping cooking, and during cooking, the displayed "off / start" of the key portion of the off / start key 48 lights up. Details of the lighting of the key unit will be described later.

The cooking power is selected by the heat key 49. The thermal power key 49 is divided into four stages of "melting heat", "low heat", "medium heat", and "high heat", and the required heating power can be set by one operation. Of the four-stage thermal power keys 49, the low heat key 49a can be set to "1", the low heat key 49b can be set to "4", the medium heat key 49c can be set to "7", and the high heat key 49d can be set to "10". The display of the part lights up.

Reference numeral 51 denotes a timer key that is mainly selected when performing timer cooking such as stewing or heat retention. Reference numeral 52 denotes a "menu" key for selecting automatic cooking of rice, fried food, boiling water, etc. By pressing the menu key 52 (touching with a finger), the menu is displayed on the upper surface display unit 10, and the menu key 52 Each time you press, the displayed menu changes, and you can select the menu to use.

In addition, the setting key 50 can be used to adjust the heating power, set the time for timer cooking, set the amount of rice for cooking rice, set the finish adjustment for automatic cooking, and set the oil temperature for deep-fried food. .. The setting key 50 includes an UP key 50a for increasing the quantity at the time of setting and a DOWN key 50b for decreasing the quantity.

Since the upper surface operation unit left 9b has the same operation and arrangement as the upper surface operation unit right 9a, the description thereof will be omitted.

Next, the upper surface operation unit center 9c will be described. The main cooking of the center 6c of the mounting part is heat retention and stewing. Therefore, the thermal power of the heating coil center 13c is also designed to be smaller than the thermal power of other heating coils. For this reason, the thermal power notation is sufficient in three stages of low heat, low heat, and medium heat, and even if the setting key 62 is a cyclic type, it will return to the original if pressed three times, so each thermal power like the two heating coils 25a and 25b in the foreground There is no thermal power setting key corresponding to.

An electrode for detecting a change in capacitance, which is an input key of the upper surface operation unit 9, is provided on an operation board 12 arranged on the lower surface of the plate 3.

The operation board 12 is divided into an operation board 12a and an operation board 12b. The operation board 12a corresponds to the upper surface operation unit right 9a and the upper surface operation unit center 9c, and the operation board 12b corresponds to the upper surface operation unit left 9b.

Reference numeral 34 denotes a cable connecting the boards.

The control circuit incorporated in the control board 19 uses the left and right inverters as control signals for cooking start, stop, and thermal power setting information based on the contents set in the upper surface operation unit 9 and a program such as automatic cooking incorporated in advance. It is sent to the substrate 18 and the central inverter substrate 17 to control the heating coil 13 and the like.

At the same time, the blower fan 20 described later is also controlled, and the blower fan 20 is operated during cooking.

Next, the details of the inverter circuit will be described with reference to FIG.

The AC voltage supplied from the power supply is rectified by the diode bridge 65 and supplied to the inverter drive unit through the choke coil 66. The inverter drive unit is composed of a pair of upper and lower arms, an IGBT 69, a snubber capacitor 70, a resonance capacitor 71, and a heating coil 13. By alternately turning on the upper and lower IGBT 69s by the control unit 80, the heating coil 13 alternates. Generates a magnetic field to supply energy to the object to be heated.
The switching elements of the upper and lower arms, IGBT 69a and 69b, are fixed to the heat sink with screws and cooled by the air blown from the blower fan 20. Further, a temperature detecting element 85 such as a thermistor is provided in the vicinity of the IGBT 69, and the control unit 80 detects the temperature of the IGBT 69.

This inverter is a current resonance type half-bridge system. Normally, the inverter operates in a state where the ON times of the IGBTs 69 of the upper and lower arms are equal to each other, and in order to prevent the simultaneous ON state, the inverters of the upper and lower arms While the ON state of the IGBT 69 is switched, a dead time is provided to turn off both the IGBT 69s. Further, by charging and discharging the snubber capacitor 70 during the dead time, the collector-emitter voltage at the moment when the IGBT 69 is turned on is brought close to 0, and the generation of a short-circuit current is suppressed.

Subsequently, the output control method of the inverter will be described.

By raising the operating frequency of the inverter and keeping it away from the resonance frequency of the inverter circuit, the current flowing through the heating (IH) coil 13 is reduced and the output is lowered. The resonance frequency of the inverter circuit is determined by the equivalent inductance determined by the heating coil 13 and the object to be heated and the capacitance of the resonance capacitor 71. The operating frequency of each heating coil 13 is set to a maximum value and a minimum value so that a roaring sound is not generated when a plurality of heating coils 13 are operated at the same time.

The IGBT 69 is overloaded when the material of the pot to be heated is a multi-layer pot made of aluminum and stainless steel, or when the bottom of the pot is deformed and the connection with the heating coil is poor (a pot inappropriate for induction heating). When the temperature rises in the state and the detection temperature of the temperature detection element 85 rises and reaches an arbitrarily determined set temperature Ta, the heating output is lowered and the IGBT temperature is controlled so as not to cause a failure.

If the temperature rises further even after performing the above control, when the set temperature Tb higher than the set temperature is reached, the heating output is further reduced to protect the IGBT, and the IGBT is used. Indicate that the pot is not suitable for heating (first notification).

There are a plurality of steps for reducing the heating output, and in this embodiment, two steps are provided, and Ta and Tb = (Ta + 5). Generally, if two stages are provided, the IGBT can be used without reaching an abnormal temperature leading to failure. This first notification is such that it is displayed on the display means 86 to the extent that it does not cause discomfort to the user, and the notification sound 87 may be sounded for a short time.

However, if the pot having a poor connection with the heating coil is used again, the operation of reducing the output is repeated in the same manner, and the user feels annoyed because the state of the reduced thermal power is repeated.

Therefore, when the cooking power is reduced and the first notification is issued a predetermined number of times (for example, 10 times), the notification means 87 (for example, voice) is used to "use" so as to urge the user to change the pot to be heated. The pot you are using is not suitable for heating due to the deformation of the material or the bottom of the pot. Please change the pot. ”(Second notification) to encourage the user to change the pot and use it. Is. Further, the content of the voice notification may be other than the above, or may be notified by an LED display or a buzzer sound, or the energization may be stopped at the same time as the notification.

By measuring the number of times of cooking with the first notification of reduced heat and setting and notifying the number of times of cooking with the first notification of reduced heat, the user can have an extra pot on hand. If there is no such pot, it is possible to eliminate the discomfort to the user by preventing frequent notification and heating stop for each cooking until the purchase of a new pot.

In addition, for example, even if you own a plurality of pots with poor connection with the heating coil, it is not necessary to specify each pot in particular, and all the pots with poor connection with the heating coil are finally notified to the user. It becomes possible to do.

According to the above-described embodiment, it is possible to provide a cooker that can be used without causing the user to feel annoyed.

Claims (1)

A heating coil that heats the object to be heated by induction heating,
An IGBT that supplies power to the heating coil and
A temperature detection element provided in the vicinity of the IGBT to detect the temperature of the IGBT, and
A control unit that controls the IGBT according to the detection temperature of the temperature detecting element and adjusts the thermal power of the heating coil to the object to be heated is provided.
When the temperature detected by the temperature detecting element reaches the set temperature Ta, the control unit lowers the thermal power, and the temperature detected by the temperature detecting element reaches the set temperature Tb set higher than the set temperature Ta. Then, the heating power is lowered, the first notification that the pot being used is inappropriate for heating is issued, and when the number of times of cooking for which the first notification is issued reaches a predetermined number, the replacement of the pot is urged. An induction cooking device characterized by giving a second notification.

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