Heating cooker

Abstract

To provide a heating cooker capable of rapidly stopping an improper continuous operation of a heating part.SOLUTION: A heating cooker includes: a pot for storing a cooked object; a lid body for openably covering an upper opening of the pot; a heating part for heating the cooked object by induction heating a heating object; a control part for outputting a drive signal to drive the heating part; a signal detection part for detecting the drive signal output from the control part; and a heating stop part for stopping power supply to the heating part. The heating stop part stops the power supply to the heating part when a duration time of the drive signal detected by the signal detection part reaches a preset upper limit time.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a cooking device that heats food contained in a pot. [Background technology]

[0002] Conventionally, as this type of cooking device, for example, the one described in Patent Document 1 is known. The cooking device described in Patent Document 1 includes a pot, a main body provided with a recess for storing the pot, and a lid for covering the upper opening of the pot stored in the recess. The main body has a heating section for induction heating the pot, a control section that outputs a drive signal for driving the heating section, a thermistor provided so as to be able to detect the temperature of the bottom of the pot, and a heating stopping section that stops the supply of power to the heating section. The heating stopping section stops the supply of power to the heating section when the thermistor reaches a predetermined temperature. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-275113 Summary of the Invention [Problem to be solved by the invention]

[0004] The cooking device of Patent Document 1 still has room for improvement in terms of quickly stopping unauthorized continuous operation of the heating unit.

[0005] Therefore, an object of the present disclosure is to solve the above-mentioned problems and to provide a cooking device that can quickly stop unauthorized continuous operation of a heating unit. [Means for solving the problem]

[0006] The cooking device according to the present disclosure includes: A pot for containing food to be cooked; A lid that can freely open and close the upper opening of the pot; A heating unit that heats an object to be heated by induction heating the object to be cooked; A control unit that outputs a drive signal for driving the heating unit; a signal detection unit that detects the drive signal output from the control unit; A heating stopping unit that stops the supply of power to the heating unit; Equipped with The heating stopping unit stops the supply of power to the heating unit when the duration of the drive signal detected by the signal detecting unit reaches a predetermined upper limit time. Effect of the Invention

[0007] According to the present disclosure, unauthorized continuous operation of the heating unit can be quickly stopped. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a cooking device according to an embodiment of the present disclosure. [Diagram 2] 2 is a cross-sectional view of the cooking device shown in FIG. 1 along line II-II. [Diagram 3] 3 is a cross-sectional view of the cooking device shown in FIG. 2 along line III-III. [Figure 4] FIG. 2 is a block diagram showing a schematic configuration of the cooking device of FIG. [Diagram 5] 2 is a diagram showing a waveform of a drive signal in the cooking device of FIG. 1. [Figure 6] 2 is a diagram showing the waveform of a signal smoothed by an integrator in the cooking device of FIG. 1. FIG. [Figure 7] 2 is a diagram showing waveforms of operation signals in the cooking device of FIG. 1. [Figure 8] FIG. 4 is a diagram showing an example of the patterns of two operation signals input to one timer IC. [Figure 9] 2 is a diagram showing patterns of operation signals AS1, AS2 in the cooking device of FIG. 1. FIG. [Figure 10] 11A and 11B are diagrams showing other patterns of the operation signals AS1 and AS2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] <Knowledge that formed the basis of this disclosure> In this type of cooking device, the heating unit may be continuously driven for a longer period than usual due to a malfunction of the control unit, which may cause the heating object (e.g., a pan) to overheat. Therefore, this type of cooking device is provided with an overheating suppression mechanism that suppresses overheating of the heating object. For example, in the cooking device described in Patent Document 1, when the thermistor reaches a predetermined temperature, the heating stop unit stops the power supply to the heating unit, thereby suppressing overheating of the heating object.

[0010] However, in conventional cooking devices, the heating unit continues to operate while the heat of the object to be heated is conducted to the thermistor and the thermistor reaches a predetermined temperature. Therefore, when the thermistor reaches the predetermined temperature, i.e., when the heating stop unit stops the power supply to the heating unit, the object to be heated may already be in an overheated state. In other words, there is a discrepancy between the actual temperature of the object to be heated and the temperature detected by the thermistor.

[0011] In particular, the temperature of a heating object with a small heat capacity rises more rapidly than that of a heating object with a large heat capacity, and so there is a tendency for the temperature of the heating object to deviate more from the temperature detected by the thermistor. Therefore, in an overheating suppression mechanism using a thermistor, the temperature of the heating object may become even higher before the power supply to the heating unit is stopped.

[0012] Therefore, from the viewpoint of the safety of the cooking appliance, it is desirable to more quickly stop unauthorized continuous operation of the heating unit.

[0013] Therefore, the inventors came up with a configuration in which a signal detection unit is provided that detects the drive signal output from the control unit, and when the duration of the drive signal detected by the signal detection unit reaches a predetermined upper limit time, the power supply to the heating unit is stopped. With this configuration, the heating stopping unit stops the power supply to the heating unit based on the duration of the drive signal actually output from the control unit, not on the temperature of the pot detected via the thermistor. Therefore, unauthorized continuous operation of the heating unit can be stopped more quickly. Based on this new finding, the inventors have come up with the following disclosure.

[0014] According to a first aspect of the present disclosure, A pot for containing food to be cooked; A lid that can freely open and close the upper opening of the pot; A heating unit that heats an object to be heated by induction heating the object to be cooked; A control unit that outputs a drive signal for driving the heating unit; a signal detection unit that detects the drive signal output from the control unit; A heating stopping unit that stops the supply of power to the heating unit; Equipped with the heating stopping unit stops the supply of power to the heating unit when a duration of the drive signal detected by the signal detecting unit reaches a predetermined upper limit time. A cooking device is provided.

[0015] According to a second aspect of the present disclosure, The heating unit inductively heats the heating object having a smaller heat capacity than the pan, the heating stopping unit stops the supply of power to the heating unit when the duration of the drive signal detected by the signal detecting unit reaches the upper limit time. The cooking device according to a first aspect is provided.

[0016] According to a third aspect of the present disclosure, The heating object is a fluid generating unit that heats a fluid supplied into the pot and generates a heated fluid, the heating stopping unit stops the supply of power to the heating unit that inductively heats the fluid generating unit when the duration of the drive signal detected by the signal detecting unit reaches the upper limit time. The cooking device according to the first or second aspect is provided.

[0017] According to a fourth aspect of the present disclosure, there is provided the cooking device according to the third aspect, wherein the heating unit inductively heats the fluid generating unit, which heats gas supplied into the pot to generate hot air.

[0018] According to a fifth aspect of the present disclosure, The lid has a heating plate that faces the food to be cooked in the pot when the lid is closed and heats the food to be cooked, the heating stopping unit stops the supply of power to the heating unit that inductively heats the heating plate when the duration of the drive signal detected by the signal detecting unit reaches the upper limit time. The cooking device according to the first or second aspect is provided.

[0019] According to a sixth aspect of the present disclosure, The pot has a bottom and a peripheral wall extending from an edge of the bottom, the heating stopping unit stops the supply of power to the heating unit that inductively heats the peripheral wall portion when the duration of the drive signal detected by the signal detecting unit reaches the upper limit time. The cooking device according to a first aspect is provided.

[0020] According to a seventh aspect of the present disclosure, the drive signal is a pulse width modulated signal; The signal detection unit a conversion unit that outputs an operation signal while the pulse width modulation signal continues; a timer IC that outputs a stop signal to the heating stop unit when the duration of the operation signal reaches a predetermined upper limit time; having The conversion unit is an integrator that time-integrates and smoothes the pulse width modulated signal; a comparator that outputs the operation signal to the timer IC when the voltage input from the integrator is greater than a predetermined reference voltage; having The heating stop unit stops the supply of power to the heating unit when the stop signal is input from the timer IC. The present invention provides a cooking device according to any one of the first to sixth aspects.

[0021] According to an eighth aspect of the present disclosure, The heating unit includes two heating units, the control unit drives the two heating units such that a continuous drive time during which at least one of the two heating units is driven is shorter than the upper limit time, the signal detection unit has two of the conversion units that output the operation signal when the pulse width modulation signal that drives each heating unit continues, The operation signal output from each conversion unit is input to one of the timer ICs. A seventh aspect of the present invention provides a cooking device.

[0022] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the following description, terms indicating specific directions or positions (e.g., terms including "up", "down", "right" and "left") are used as necessary, but the use of these terms is for the purpose of facilitating understanding of the present disclosure with reference to the drawings, and the meanings of these terms do not limit the technical scope of the present disclosure. In addition, the following description is merely illustrative in nature and is not intended to limit the present disclosure, its applications, or its uses. Furthermore, the drawings are schematic, and the ratios of the dimensions do not necessarily correspond to the actual ones.

[0023] <Embodiment> A cooking device according to an embodiment of the present disclosure will be described with reference to Fig. 1 to Fig. 3. Fig. 1 is a perspective view of a cooking device according to an embodiment of the present disclosure. Fig. 2 is a cross-sectional view of the cooking device of Fig. 1 taken along line II-II. Fig. 3 is a cross-sectional view of the cooking device of Fig. 2 taken along line III-III.

[0024] The cooking device 1 is a cooking device that heats food to be cooked. In this embodiment, the cooking device 1 will be described as being a pressure rice cooker.

[0025] 1 and 2, the cooking device 1 includes a substantially cylindrical main body 2 with a bottom, in which a pot storage section 21 is formed, and a pot 3 that is stored in the pot storage section 21 and that contains food to be cooked CK, including rice and water. A lid 4 is attached to the top of the main body 2, and covers an upper opening 34 of the pot 3 in an openable and closable manner.

[0026] 2, pot 3 has a bottom 31, a peripheral wall 32 extending upward from an edge 311 of bottom 31, and a pot flange 33 protruding outward from an upper edge of peripheral wall 32. The upper edge of peripheral wall 32 defines an upper opening 34 of pot 3. In this embodiment, pot 3 has a multi-layer structure having a layer made of aluminum and a layer made of stainless steel.

[0027] Pot storage section 21 of main body 2 has a tubular section 211 arranged to leave a specified gap with peripheral wall section 32 of stored pot 3, and a main body flange section 212 protruding outward from the upper part of tubular section 211. The upper end of tubular section 211 supports pot flange section 33 when pot 3 is stored in pot storage section 21.

[0028] An opening is provided in the center of the bottom of the cylindrical portion 211. A temperature sensor 22 for measuring the temperature of the bottom 31 of the pot 3 is arranged in this opening so as to be able to abut against the bottom 31 of the pot 3 stored in the pot storage portion 21. The temperature of the pot 3 is approximately the same as the temperature of the food CK stored in the pot 3. Therefore, by detecting the temperature of the pot 3 with the temperature sensor 22, the temperature of the food CK can be detected.

[0029] Cylindrical section 211 has an outer peripheral surface 211a on the opposite side to the surface facing pot 3 stored in pot storage section 21. A bottom coil 23 and a wall coil 24 are attached to outer peripheral surface 211a, which inductively heat pot 3 and heat the food CK to be cooked. Wall coil 24 is an example of a "heating section" in this disclosure.

[0030] Bottom coil 23 is disposed around the opening provided in cylindrical portion 211 so as to face bottom 31 of pot 3 in the up-down direction. Wall coil 24 is disposed away from bottom coil 23 so as to face peripheral wall 32 of pot 3. Bottom coil 23 heats bottom 31 of pot 3, and wall coil 24 heats peripheral wall 32 of pot 3.

[0031] As shown in Fig. 2, in the pot 3 during cooking or keeping warm, the inner surface of the bottom 31 contacts the food CK over the entire surface or almost the entire surface, regardless of the amount of food CK. Therefore, a large amount of heat is transferred from the bottom 31 to the food CK, and the temperature of the bottom 31 does not easily rise. On the other hand, only a part of the inner surface of the peripheral wall 32 contacts the food CK. Therefore, a small amount of heat is transferred from the peripheral wall 32 to the food CK, and the temperature of the peripheral wall 32 is more likely to rise than the temperature of the bottom 31. In particular, when the amount of food CK is small, the contact area of ​​the inner surface of the peripheral wall 32 with the food CK becomes even smaller, and the temperature of the peripheral wall 32 is more likely to rise.

[0032] The lid body 4 includes an upper outer casing member 41 and a lower outer casing member 42 that form the outer casing of the lid body 4. The upper outer casing member 41 and the lower outer casing member 42 define the internal space of the lid body 4. A hinge (not shown) that connects the lid body 4 to the main body flange portion 212 is provided at the rear part of the lid body 4. The lid body 4 opens and closes by rotating about the hinge.

[0033] 2, the lid 4 has a heating plate 44 that faces the food CK in the pot 3 when the lid 4 is closed and heats the food CK. In this embodiment, the heating plate 44 is configured as a substantially disk-shaped inner lid that is attached to the lower surface of the lower outer casing member 42 (the surface that faces the bottom 31 of the pot 3 when the lid 4 is closed). When the lid 4 is closed, the heating plate 44 comes into contact with the pot flange 33 and seals the upper opening 34 of the pot 3.

[0034] The central portion of heating plate 44 in a plan view is formed as protrusion 441 that protrudes into pot 3 when lid 4 is in the closed state.

[0035] A heating plate coil 45 that inductively heats the heating plate 44 via the lower outer casing member 42 is provided in the internal space of the lid 4. The heating plate coil 45 is an example of a "heating section" in the present disclosure. In the present embodiment, the heating plate coil 45 is provided on the inner surface 42a of the lower outer casing member 42 at a position facing the heating plate 44 via the lower outer casing member 42.

[0036] The heating plate coil 45 inductively heats the heating plate 44 during operation of the cooking device 1. The heated heating plate 44 heats the food CK contained in the pot 3 and the air in the internal space of the pot 3.

[0037] In this embodiment, heating plate 44 is made of stainless steel. Furthermore, the mass of heating plate 44 is smaller than the mass of pot 3. The heat capacity of heating plate 44 is smaller than the heat capacity of pot 3. Here, heat capacity (J / K) is the amount of heat required to raise the temperature of an object by a unit temperature (e.g., 1 K), and is expressed as the product of the specific heat (J / (kg K)) and mass (kg) of the object.

[0038] 3, a fluid generating unit 5 is further provided in the internal space of the lid 4. The fluid generating unit 5 heats a fluid such as water, steam, or air, and supplies it to the inside of the pot 3 during operation of the cooking appliance 1. In this embodiment, the fluid generating unit 5 heats air and sends hot air into the inside of the pot 3.

[0039] Fluid generating unit 5 has pump 51 that sucks air from the internal space of lid 4, fluid conduit 52 that heats the air passing through the inside, and tube 53 that connects pump 51 and fluid conduit 52. Fluid conduit 52 is in fluid communication with the inside of pot 3 via air outlet 442 provided in protruding portion 441 of heating plate 44.

[0040] Pump 51 sucks air from the internal space of lid 4 and supplies the air to the inside of pot 3 via tube 53 and fluid conduit 52. Here, the internal space of lid 4 communicates with the outside of cooking appliance 1 via the gap between upper outer casing member 41 and lower outer casing member 42, so that pump 51 can supply outside air to the inside of pot 3.

[0041] Fluid conduit 52 is made of a metal that can be inductively heated. In this embodiment, fluid conduit 52 is made of iron, and is disposed near air outlet 442 provided in protruding portion 441 of heating plate 44. The mass of fluid conduit 52 is smaller than both the mass of pot 3 and the mass of heating plate 44. The heat capacity of fluid conduit 52 is smaller than both the heat capacity of pot 3 and the heat capacity of heating plate 44. Tube 53 is, for example, a rubber tube.

[0042] A fluid conduit coil 54 is provided around the fluid conduit 52 to heat the air passing through the fluid conduit 52 by inductively heating the fluid conduit 52. The fluid conduit coil 54 is an example of a "heating section" in the present disclosure. The fluid conduit coil 54 is formed so as to wind around the fluid conduit 52. In the following description, for convenience of explanation, the four coils, the bottom coil 23, the wall coil 24, the heating plate coil 45, and the fluid conduit coil 54, may be referred to as heating coils 100.

[0043] The air sucked in by the pump 51 is heated by the fluid conduit 52, which is induction heated by the fluid conduit coil 54, while passing through the fluid conduit 52, and reaches the air outlet 442 of the heating plate 44 (inner lid). This allows hot air to be supplied to the inside of the pot 3 while the cooking device 1 is in operation. The hot air heats the food CK to be cooked.

[0044] 2, the cooking device 1 is provided with a control board 6. In this embodiment, the control board 6 has a first board 601 located inside the lid 4 and having a control unit 61 mounted thereon, and a second board 602 located inside the main body 2.

[0045] The control unit 61 includes a storage unit that stores a plurality of rice cooking sequences for cooking the food CK containing rice and water, and at least one warming sequence for keeping the cooked food CK warm. Here, the term "rice cooking sequence" refers to a rice cooking procedure in which the time of current application to each heating coil 100 used for induction heating, the heating temperature, the heating time, the temperature and air volume of the hot air generated by the fluid generating unit 5, and the like are predetermined in a plurality of steps for cooking rice. Each rice cooking sequence corresponds to one of a plurality of rice cooking courses executed in the cooking device 1. Also, the term "warming sequence" refers to a warming procedure in which the time of current application to each heating coil 100, the heating temperature, the heating time, the temperature and air volume of the hot air generated by the fluid generating unit 5, and the like are predetermined.

[0046] The control unit 61 is electrically connected to the temperature sensor 22, the pump 51 of the fluid generating unit 5, and each heating coil 100. Here, "electrically connected" includes all of the following: current can be conducted between multiple components, multiple components are capacitively coupled, and multiple components are electromagnetically coupled. The control unit 61 outputs a drive signal to drive the pump 51 of the fluid generating unit 5 and each heating coil 100 based on the temperature of the bottom 31 of the pan 3 measured by the temperature sensor 22, etc. In this way, the control unit 61 executes a rice cooking process for cooking the food CK to be cooked, and a warming process for keeping the food CK warm after cooking.

[0047] In this embodiment, the control unit 61 is a microcontroller.

[0048] The cooking device 1 is provided with an overheating suppression mechanism that suppresses overheating of an object to be heated by induction heating during operation of the cooking device 1. Here, the objects to be heated in this embodiment are the pan 3 heated by the bottom coil 23 and the wall coil 24, the heating plate 44 heated by the heating plate coil 45, and the fluid conduit 52 heated by the fluid conduit coil 54.

[0049] The electrical connections and the above-mentioned overheat suppression mechanism in the cooking device 1 will be described with reference to Fig. 4. Fig. 4 is a block diagram showing a schematic configuration of the cooking device in Fig. 1.

[0050] As shown in FIG. 4, in this embodiment, the second substrate 602 has a power supply connection section 69, an AC-DC conversion section 62, and an inverter circuit 63 mounted thereon.

[0051] The power supply connection unit 69 is a connection portion to an external power supply such as a commercial power supply, a generator, or a power storage device. A part of the power supply connection unit 69 is exposed to the outside for connection to the external power supply, but is omitted in FIG. 1. Electric power is supplied to the cooking appliance 1 via the power supply connection unit 69. In this embodiment, the power supply connection unit 69 is, for example, a plug that is connected to a household outlet. An alternating current voltage (AC voltage) is supplied to the power supply connection unit 69 as electric power.

[0052] The AC-DC conversion unit 62 converts the AC voltage supplied via the power supply connection unit 69 into a direct current voltage (DC voltage), and supplies the DC voltage to the inverter circuit 63 .

[0053] In response to a drive signal from the control unit 61, the DC voltage output from the AC-DC conversion unit 62 is converted into a high-frequency current and supplied to the heating coils 100. When the high-frequency current flows through each heating coil 100, the object to be heated by each heating coil 100 is inductively heated.

[0054] The control unit 61 outputs a drive signal for driving each heating coil 100 to the inverter circuit 63. In this embodiment, the drive signal is a pulse width modulation signal (PWM signal). The PWM signal is a pulse wave that repeats on and off in a constant cycle, and is controlled by changing the ratio of on time (duty ratio) in each cycle. In this embodiment, the larger the duty ratio of the drive signal, the stronger the heating power of the heating coil 100 controlled by the drive signal.

[0055] In FIG. 4, the connection between the control unit 61 and the inverter circuit 63 via the heating stop unit 64 described later is shown by a single line, but the connection may also be by multiple paths corresponding to each heating coil 100, for example.

[0056] Between the control unit 61 and the inverter circuit 63, there is a heating stopping unit 64 mounted on the first substrate 601. The heating stopping unit 64 is configured to be able to stop the supply of power to each heating coil 100. In this embodiment, the heating stopping unit 64 is configured to be able to switch whether or not to cut off the transmission of a drive signal from the control unit 61 to the inverter circuit 63. In this embodiment, when a stop signal described later is input, the heating stopping unit 64 cuts off the transmission of the drive signal to the inverter circuit 63, thereby stopping the supply of power to all of the heating coils 100.

[0057] The cooking device 1 has two overheating prevention mechanisms for preventing overheating of an object to be heated. The first overheating prevention mechanism is a mechanism for stopping the supply of power to each heating coil 100 based on the temperature of the pan 3 detected by the temperature sensor 22.

[0058] For the first overheat suppression mechanism, a comparator 65 is mounted on the first substrate 601. The comparator 65 is electrically connected to each of the temperature sensor 22 and the heating stop unit 64.

[0059] Comparator 65 compares the temperature detected by temperature sensor 22 with a predetermined upper limit temperature of pot 3. When the temperature detected by temperature sensor 22 is equal to or higher than the upper limit temperature, comparator 65 outputs a stop signal to heating stop unit 64. The stop signal is a signal for switching heating stop unit 64 so as to cut off transmission of the drive signal to inverter circuit 63.

[0060] In this embodiment, the comparator 65 compares the voltage output from the temperature sensor 22 with a reference voltage corresponding to an upper limit temperature of approximately 200° C. When the voltage output from the temperature sensor 22 is equal to or higher than the reference voltage, the comparator 65 switches the heating stop unit 64 so as not to transmit the drive signal output from the control unit 61 to the inverter circuit 63.

[0061] The second overheating suppression mechanism is a mechanism that stops the power supply to each heating coil 100 based on the duration of the drive signal output from the control unit 61.

[0062] Fig. 5 is a diagram showing the waveform of a drive signal in the cooking device of Fig. 1. As shown in Fig. 5, when the drive signal is a PWM signal, the continuation of the drive signal is a state in which a period with an on time is repeated without loss, as shown in Fig. 5. In other words, the continuation of the drive signal is a state in which a period with a duty ratio exceeding 0% is repeated.

[0063] 4, the first substrate 601 is provided with a signal detection unit 66 that detects a drive signal output from the control unit 61. The signal detection unit 66 has two conversion units 67A and 67B and one timer IC 68.

[0064] Each of the conversion units 67A, 67B outputs an operation signal when the pulse width modulation signal for driving each heating coil 100 continues. Each of the conversion units 67A, 67B is connected to the control unit 61.

[0065] The control unit 61 outputs three drive signals SG1 to SG3. The drive signal SG1 is a drive signal for driving the wall coil 24 and the heating plate coil 45. The drive signal SG2 is a drive signal for driving the fluid conduit coil 54. The drive signal SG3 is a drive signal for driving the bottom coil 23.

[0066] 4, the drive signal SG1 is output from the control unit 61 to the inverter circuit 63 and the conversion unit 67A. The drive signal SG2 is output from the control unit 61 to the inverter circuit 63 and the conversion unit 67B. The drive signal SG3 is output from the control unit 61 to the inverter circuit 63.

[0067] Each of the conversion units 67A and 67B has an integrator 671 connected to the control unit 61 and a comparator 672 connected downstream of the integrator 671.

[0068] The integrator 671 time-integrates the pulse width modulation signals SG1 and SG2, and outputs the smoothed signal to the comparator 672. FIG. 6 is a diagram showing the waveform of a smoothed signal output from the integrator when the drive signal shown in FIG. 5 is input to the integrator. As shown in FIG. 6, the waveform of the signal output from the integrator 671 is smoothed in the continuous portion in which the PWM signal continues. That is, in the continuous portion, the voltage when the signal is on is lowered and the voltage when the signal is off is raised, compared to the PWM signal. In addition, in the continuous portion, when the duty ratio of the PWM signal is large, the voltage is higher than when the duty ratio is low. In this embodiment, the integrator 671 is a low-pass filter composed of a capacitor and a resistor.

[0069] When the voltage input from the integrator 671 is greater than a predetermined reference voltage, the comparator 672 outputs an operation signal to the timer IC 68. Fig. 7 is a diagram showing the waveform of the operation signal output from the comparator when the signal shown in Fig. 6 is input to the comparator.

[0070] The reference voltage of the comparator 672 is set to be smaller than the voltage of the smoothed signal corresponding to a low duty ratio (e.g., 1%) of the drive signals SG1 and SG2. As a result, the comparator 672 outputs the operation signals AS1 and AS2 when the drive signals SG1 and SG2 are continuing, regardless of the duty ratio of the drive signals SG1 and SG2. Moreover, the comparator 672 does not output an operation signal when the drive signals SG1 and SG2 are not continuing. In this embodiment, the comparator 672 outputs a voltage of 5V to the timer IC 68 as the operation signals AS1 and AS2.

[0071] The timer IC 68 detects the time during which a voltage greater than a predetermined threshold voltage is continuously input, and outputs a stop signal to the heating stopping unit 64 when the time reaches a predetermined upper limit time. Here, the threshold voltage of the timer IC 68 is set to be smaller than the voltage (e.g., 5V) of the operation signal output from the comparator 672. In this embodiment, the threshold voltage of the timer IC 68 is 3V. As a result, the timer IC 68 outputs a stop signal to the heating stopping unit 64 when the duration of the operation signal input from the comparator 672 reaches the upper limit time.

[0072] The upper limit time of the timer IC 68 is set to be longer than the longest duration of each of the drive signals SG1, SG2 in a normally operating cooking appliance 1. In this embodiment, the upper limit time is 30 seconds.

[0073] The operation signals SG1 and SG2 are input to the timer IC 68 from the comparator 672 of the conversion unit 67A and the comparator 672 of the conversion unit 67B. The timer IC 68 outputs a stop signal to the heating stop unit 64 when the continuous time during which at least one of the drive signals SG1 and SG2 that drive the heating plate coil 45 is on reaches 30 seconds.

[0074] When the stop signal is input, the heating stopping unit 64 cuts off the transmission of the drive signals SG1 to SG3 from the control unit 61 to the inverter circuit 63, similar to the first overheating prevention mechanism.

[0075] When operation signals AS1 and AS2 are input to timer IC 68, if operation signals AS1 and AS2 overlap, timer IC 68 may erroneously detect that the upper limit time has been reached even though the duration of each of operation signals AS1 and AS2 does not reach the upper limit time.

[0076] Fig. 8 is a diagram showing an example of two operation signals input to one timer IC. In the example shown in Fig. 8, each of the two operation signals turns off every 20 seconds, and the upper limit time of the timer IC, which is 30 seconds, has not been reached. However, since the last 5 seconds of one operation signal overlaps with the first 5 seconds of the other operation signal, the timer IC erroneously detects that the upper limit time has been reached.

[0077] To prevent this erroneous detection, in the cooking device 1, the continuous time during which at least one of the two operation signals AS1 and AS2 is ON is set to be shorter than the upper limit time of the timer IC 68. In other words, the control unit 61 controls the wall coil 24, the heating plate coil 45, and the fluid conduit coil 54 so that the continuous driving time during which at least one of the wall coil 24, the heating plate coil 45, and the fluid conduit coil 54 is driven is shorter than the upper limit time (e.g., 30 seconds) of the timer IC 68.

[0078] Fig. 9 is a diagram showing the patterns of the operation signals AS1 and AS2 in the cooking device of Fig. 1. As shown in Fig. 9, the operation signal AS1 is turned on for 15 seconds and then turned off for 15 seconds, repeating this cycle. On the other hand, the operation signal AS2 is turned on at the same time as the operation signal AS1, continues to be on for 29 seconds, and then turns off for 1 second, repeating this cycle. In other words, the control unit 61 repeats a cycle of driving the wall coil 24 and the heating plate coil 45 for 15 seconds and then not driving them for 15 seconds. Also, the control unit 61 repeats a cycle of driving the fluid conduit coil 54 for 29 seconds and then not driving it for 1 second.

[0079] According to the above control, there is always one timing when both operation signals AS1 and AS2 are turned off every 30 seconds, which is the upper limit time of timer IC 68. This makes it possible to prevent the above-mentioned erroneous detection during normal operation of cooking appliance 1. Also, compared with a configuration in which two timer ICs corresponding to each conversion unit 67A, 67B are provided, the number of timer ICs can be reduced.

[0080] According to the cooking device 1 of this embodiment, when the duration of the drive signal detected by the signal detection unit 66 reaches a predetermined upper limit time, the drive of the heating coil 100 is stopped. Therefore, unauthorized continuous operation of the heating coil 100 can be stopped more quickly than in conventional cooking devices that stop the drive of the heating coil 100 based on the temperature of the object to be heated.

[0081] Moreover, according to the cooking device 1, unlike conventional cooking devices, there is no need to provide a thermistor near each object to be heated. Furthermore, the signal detection unit 66 can be configured as a part of the control board 6 on which the control unit 61 is mounted. Therefore, compared to conventional cooking devices, the design freedom of the cooking device 1 is improved. This makes it possible to realize, for example, a reduction in size of the cooking device 1 and an improvement in design.

[0082] Furthermore, in the cooking device 1 according to this embodiment, the heating stopping unit 64 stops the power supply to the heating plate coil 45 or the fluid conduit coil 54, which heats the heating plate 44 or the fluid conduit 52, which have a smaller heat capacity than the pan 3, based on the duration of the drive signals SG1 and SG2. This makes it possible to further prevent overheating of the heating plate 44 and the fluid conduit 52, which are prone to a sudden increase in temperature. Therefore, the safety of the cooking device 1 is further improved.

[0083] The fluid conduit 52 heated by the fluid conduit coil 54 is smaller than the pan 3. Therefore, the heat capacity of the fluid conduit 52 is smaller than the heat capacity of the pan 3. In the cooking device 1 according to this embodiment, the heating stopping unit 64 stops the power supply to the fluid conduit coil 54 based on the duration of the drive signal SG2. This makes it possible to further prevent overheating of the fluid conduit 52, which has a small heat capacity and is prone to a sudden increase in temperature. This further improves the safety of the cooking device 1.

[0084] The thermal conductivity of gas tends to be lower than that of liquid. Therefore, when heating gas through the fluid conduit 52, it is necessary to increase the amount of heat from the fluid conduit coil 54 to the fluid conduit 52 compared to when heating a liquid. The greater the amount of heat in the fluid conduit coil 54, the steeper the temperature rise in the fluid conduit 52 heated by the fluid conduit coil 54. Therefore, in an overheating suppression mechanism using a thermistor, the discrepancy between the temperature detected by the thermistor and the actual temperature of the fluid conduit 52 becomes large.

[0085] On the other hand, in the cooking device 1 according to the present embodiment, the heating stopping unit 64 stops the power supply to the fluid conduit coil 54 that heats the gas through the fluid conduit 52 based on the duration of the drive signal SG2. This makes it possible to further prevent overheating of the fluid conduit 52 to which a large amount of heat is applied. This further improves the safety of the cooking device 1.

[0086] Since the mass of the heating plate 44 is smaller than the mass of the pan 3, the heat capacity of the heating plate 44 is smaller than the heat capacity of the pan 3. According to the cooking device 1 of this embodiment, the heating stop unit 64 stops the power supply to the heating plate coil 45 when the duration of the drive signal SG1 that drives the heating plate coil 45 that heats the heating plate 44 reaches the upper limit time. This makes it possible to further prevent overheating of the heating plate 44, which has a small heat capacity and is prone to a sudden rise in temperature. Therefore, the safety of the cooking device 1 is further improved.

[0087] In the pot 3 during cooking or keeping warm, the temperature is more likely to rise in the parts not in contact with the food CK than in the parts in contact with the food CK. Specifically, the temperature of the inner surface of the bottom 31 is less likely to rise because the entire surface or nearly the entire surface of the inner surface is in contact with the food CK, regardless of the amount of food CK. On the other hand, the temperature of the inner surface of the peripheral wall 32 is more likely to rise because only a part of the inner surface is in contact with the food CK. Also, the smaller the amount of food CK, the smaller the contact area between the inner surface of the peripheral wall 32 and the food Ck, and the more likely the temperature of the peripheral wall 32 will rise.

[0088] According to the cooking device 1 of this embodiment, the heating stopping unit 64 stops the power supply to the wall coil 24 that heats the peripheral wall 32, which is more likely to rise in temperature, based on the duration of the drive signal SG1. This makes it possible to further prevent overheating of the peripheral wall 32, which is particularly likely to rise in temperature, in the pot 3. This further improves the safety of the cooking device 1.

[0089] Moreover, according to the cooking device 1 of this embodiment, a timer IC 68 is provided to detect when the duration of the drive signals SG1 and SG2 reaches an upper limit time. The timer IC 68 detects the time during which the voltage of the input signal continuously exceeds a predetermined voltage, and outputs a stop signal to the heating stop unit 64 when the time exceeds a predetermined upper limit time. The voltage of the pulse width modulated signal, which is a rectangular wave, becomes lower than the predetermined voltage of the timer IC 68 when the pulse is off. Therefore, if the pulse width modulated signal is directly input to the timer IC 68, the timer IC is reset for each pulse, and it is not possible to detect the duration of the drive signals SG1 and SG2, i.e., the duration of a series of pulse width modulated signals.

[0090] According to the cooking device 1 of this embodiment, the pulse width modulated signal is smoothed by the integrator 671 and input to the comparator 672, so that while the pulse width modulated signal continues, constant operation signals AS1, AS2 can be output from the comparator 672. By inputting the operation signals AS1, AS2 to the timer IC 68, the duration of the pulse width modulated signal can be detected using the timer IC 68.

[0091] According to the cooking device 1 of this embodiment, the two operation signals AS1, AS2 output from the two conversion units 67A, 67B are input to one timer IC 68. This makes it possible to reduce the number of timer ICs compared to a configuration in which two timer ICs are provided corresponding to the two drive signals SG1, SG2.

[0092] When multiple operating signals AS1 and AS2 are input to one timer IC 68, the timer IC will not be reset as long as at least one operating signal is input. Therefore, when two operating signals AS1 and AS2 overlap with a time lag, it is possible that a stop signal will be output from the timer IC 68 even if the duration of each operating signal AS1 and AS2 does not exceed the upper limit time.

[0093] However, in the cooking device 1, the control unit 61 drives the wall coil 24, the heating plate coil 45, and the fluid conduit coil 54 so that the continuous drive time is shorter than the upper limit time. In other words, the two drive signals AS1, AS2 that drive the wall coil 24, the heating plate coil 45, and the fluid conduit coil 54, respectively, are stopped simultaneously at least once within the upper limit time. As a result, in a cooking device 1 that is operating normally, the timer IC 68 is reset at least once within the upper limit time, preventing an erroneous output of a stop signal.

[0094] The present disclosure is not limited to the above embodiment, and can be implemented in various other aspects. For example, the cooking device 1 is a pressure rice cooker in the above, but the present disclosure is not limited to this. For example, the cooking device 1 may be a non-pressure rice cooker, an automatic cooking pot, a pressure cooking pot, an oven range, etc.

[0095] In the above description, the drive signal SG3 for driving the bottom coil 23 is not detected by the signal detection unit 66, but the present disclosure is not limited to this. For example, the signal detection unit 66 may further include a converter corresponding to the drive signal SG3 and a timer IC arranged downstream thereof, and when the duration of the drive signal SG3 reaches an upper limit time, the power supply to all of the heating coils 100 may be stopped.

[0096] In the above description, the driving signal SG1 drives two heating coils 100 (i.e., the wall coil 24 and the heating plate coil 45), but the present disclosure is not limited to this. For example, each driving signal may drive only one heating coil 100, or may drive three or more heating coils 100.

[0097] In the above description, the heating stopping unit 64 stops the power supply to all of the heating coils 100 when a stop signal is input, but the power supply may be stopped to some of the heating coils 100. For example, the heating stopping unit 64 may stop the power supply to the heating coils 100 driven by the drive signal that caused the stop signal to be output from the timer IC. For example, when a stop signal is input to the heating stopping unit 64 because the duration of the drive signal SG2 has reached an upper limit time, the heating stopping unit 64 may stop the power supply only to the fluid conduit coil 54 driven by the drive signal SG2 based on the stop signal.

[0098] In the above description, the heating stopping unit 64 stops the power supply to each heating coil 100 by cutting off the transmission of the drive signals SG1 to SG3, but the present disclosure is not limited to this. For example, the heating stopping unit 64 may be electrically connected between the inverter circuit 63 and each heating coil 100 and configured to cut off the power supply from the inverter circuit 63 to each heating coil 100.

[0099] The pattern of the operation signals AS1 and AS2 is not limited to the pattern shown in the embodiment (see FIG. 9). FIG. 10 is a diagram showing another pattern of the operation signals AS1 and AS2. In the pattern shown in FIG. 10, the operation signal AS1 repeats a cycle of being on for 14 seconds and then off for 16 seconds. On the other hand, the operation signal AS2 repeats a cycle of being on one second after the operation signal AS1 turns off, remaining on for 14 seconds, and then off for 16 seconds. According to this control, there are always two timings when both the operation signals AS1 and AS2 are off every 30 seconds, which is the upper limit time of the timer IC 68. Moreover, in the pattern shown in FIG. 10, the two operation signals AS1 and AS2 do not overlap.

[0100] Any of the various embodiments or modifications described above can be appropriately combined to achieve the effects of each of them. In addition, combinations of embodiments, combinations of examples, or combinations of embodiments and examples are possible, and combinations of features of different embodiments or examples are also possible.

[0101] Although the present disclosure has been fully described in connection with the preferred embodiments with reference to the accompanying drawings, various changes and modifications will be apparent to those skilled in the art, and such changes and modifications should be understood to be included within the scope of the present disclosure as defined by the appended claims unless they depart therefrom. [Industrial Applicability]

[0102] The present disclosure is applicable to a cooking device that heats food contained in a pot. [Explanation of symbols]

[0103] 1 Cooker 2 Main unit 24 Wall coil 3. Pot 31 Bottom 311 Edge 32 Peripheral wall part 34 Top opening 4 Lid 44 Heating plate 45 Heating plate coil 5 Fluid generation section 52 Fluid conduit 54 Fluid conduit coil 6 Control Board 61 Control section 64 Heating stop section 66 Signal detection unit 67A,67B conversion unit 671 Integrator 672 Comparator 68 Timer IC CK Cooked item

Claims

1. A pot for containing food to be cooked; A lid that can freely open and close the upper opening of the pot; A heating unit that heats an object to be heated by induction heating the object to be cooked; A control unit that outputs a drive signal for driving the heating unit; a signal detection unit that detects the drive signal output from the control unit; A heating stopping unit that stops the supply of power to the heating unit; Equipped with the heating stopping unit stops the supply of power to the heating unit when a duration of the drive signal detected by the signal detecting unit reaches a predetermined upper limit time. Heating cooker.

2. The heating unit inductively heats the heating object having a smaller heat capacity than the pan, the heating stopping unit stops the supply of power to the heating unit when the duration of the drive signal detected by the signal detecting unit reaches the upper limit time. The cooking device according to claim 1 .

3. The heating object is a fluid generating unit that heats a fluid supplied into the pot and generates a heated fluid, the heating stopping unit stops the supply of power to the heating unit that inductively heats the fluid generating unit when the duration of the drive signal detected by the signal detecting unit reaches the upper limit time. The cooking device according to claim 1 or 2.

4. The cooking device according to claim 3 , wherein the heating unit inductively heats the fluid generating unit that heats the gas supplied into the pot to generate hot air.

5. The lid has a heating plate that faces the food to be cooked in the pot when the lid is closed and heats the food to be cooked, the heating stopping unit stops the supply of power to the heating unit that inductively heats the heating plate when the duration of the drive signal detected by the signal detecting unit reaches the upper limit time. The cooking device according to claim 1 or 2.

6. The pot has a bottom and a peripheral wall extending from an edge of the bottom, the heating stopping unit stops the supply of power to the heating unit that inductively heats the peripheral wall portion when the duration of the drive signal detected by the signal detecting unit reaches the upper limit time. The cooking device according to claim 1 .

7. the drive signal is a pulse width modulated signal; The signal detection unit a conversion unit that outputs an operation signal while the pulse width modulation signal continues; a timer IC that outputs a stop signal to the heating stop unit when the duration of the operation signal reaches a predetermined upper limit time; having The conversion unit is an integrator that time-integrates and smoothes the pulse width modulated signal; a comparator that outputs the operation signal to the timer IC when the voltage input from the integrator is greater than a predetermined reference voltage; having The heating stop unit stops the supply of power to the heating unit when the stop signal is input from the timer IC. The cooking device according to claim 1 .

8. The heating unit includes two heating units, the control unit drives the two heating units such that a continuous drive time during which at least one of the two heating units is driven is shorter than the upper limit time, the signal detection unit has two of the conversion units that output the operation signal when the pulse width modulation signal that drives each heating unit continues, The operation signal output from each conversion unit is input to one of the timer ICs. The cooking device according to claim 7.

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