JP2024024507A - microwave oven - Google Patents

Abstract

An object of the present invention is to provide a microwave oven that can suppress overheating and underheating of food at the same time. A microwave oven (1) includes a heating chamber (12), a microwave source (30), a sensor (35) for detecting steam generated from a food (C) to be cooked, and a control unit (45) for heating the food (C). The heat treatment has a normal end step (step S5) and a preventive end step (steps S6 to S8), and in the preventive end step, the amount of steam per unit time obtained from the detection result of the sensor 35 is Set steam that is less than the first maximum amount of steam that is the maximum amount of steam per unit time generated from the object C1 and greater than the second maximum amount of steam that is the maximum amount of steam per unit time that is generated from the second object C2. It includes a first step (step S6) that ends when it is indicated that the amount has been reached. [Selection diagram] Figure 5

Description

The present invention relates to a microwave oven.

In the microwave oven disclosed in Patent Document 1, a manual heating process in which a user manually sets a heating time is provided with a function of suppressing overheating of food due to an erroneous operation. This overheating suppression function automatically sets a second heating time according to the weight without following the first heating time when the manually set first heating time does not match the weight of the food detected by the weight sensor. , the heating treatment is terminated when the second heating time has elapsed.

Japanese Patent Application Publication No. 9-213472

In the microwave oven of Patent Document 1, the heating time is only changed depending on the weight of the food, and no consideration is given to the actual heating state of the food. Therefore, depending on the food being cooked, the microwave oven may be overheated or underheated, and there is room for improvement in the microwave oven of Patent Document 1 in terms of suppressing overheating and underheating of the food.

An object of the present invention is to provide a microwave oven that can suppress overheating and underheating of food at the same time.

One aspect of the present invention includes a heating chamber for heating food, a microwave source that outputs microwaves for heating the food, a sensor for detecting steam generated from the food, and a manual setting. and a control unit that outputs microwaves from the microwave source to heat the food based on the heating time, the food being cooked is a first food and the food is longer than the first food. a second cooked food having a large volume and a high moisture content, and the heating treatment by the control unit includes a normal termination step that ends when the heating time elapses, and a preventive termination step that ends before the heating time elapses. and the preventive termination step is such that the amount of steam per unit time obtained from the detection result of the sensor is less than the first maximum amount of steam that is the maximum amount of steam per unit time generated from the first food to be cooked. , a first step that ends when it is indicated that a set amount of steam that is greater than a second maximum amount of steam, which is the maximum amount of steam generated per unit time from the second cooking object, is reached.

The first cooked food includes ingredients such as potatoes and sweet potatoes that contain a lot of water and have a small volume. The temperature of the first cooking item (for example, potatoes) rises rapidly due to heating, and the amount of steam generated from the first cooking item per unit time ranges from a small amount like steam that gradually oozes out to a large amount and a sudden increase. It becomes a state where it spews out (first maximum amount of steam). However, the first cooking item may be overheated when it reaches the first maximum amount of steam, and is not suitable as a food material in an overheated state.

The second cooked food includes dishes such as curry and stews that contain more water and have a larger volume than the first cooked food. The temperature rise of the second cooking item (for example, curry) due to heating is slower than that of the first cooking item, and the amount of steam generated from the second cooking item per unit time always gradually oozes out (second maximum). amount of steam). However, the second food may be underheated when it reaches the second maximum amount of steam, and the underheated state is not suitable for cooking.

In contrast, the heat treatment of this embodiment has a normal termination step that ends when a manually set heating time elapses, and a preventive termination step that ends before the heating time elapses. The method includes a first step that ends when the detection result indicates that the amount of steam per unit time has reached the set amount of steam. In this way, the preventive termination step is performed based on the detection result of the sensor that detects the steam generated from the food, that is, the heating state of the food, rather than the weight of the food. Moreover, the set amount of steam to be compared with the amount of steam obtained from the detection result of the sensor is smaller than the first maximum amount of steam, which is the maximum amount of steam generated per unit time from the first food. Since the heating state before a large amount of steam is generated (overheating), that is, a small amount of steam exuding from the first food, can be detected, overheating of the first food can be suppressed. In addition, since the set amount of steam is higher than the second maximum amount of steam, which is the maximum amount of steam generated per unit time from the second cooking item, even if steam is generated from the second cooking item, the process will proceed to the prevention termination process. Since the second food item is heated until the manually set heating time without heating, insufficient heating of the second food item can be suppressed. That is, in this aspect, it is possible to suppress overheating and underheating of the food at the same time.

Specifically, the control unit determines the amount of steam based on the input voltage from the sensor, and in the first step, the input voltage from the sensor is determined when the input voltage from the sensor is generated from the first food. A second equivalent voltage that is lower than a first equivalent voltage corresponding to a first maximum rising slope due to the steam, has a gentler slope than the first maximum rising slope, and corresponds to a second maximum rising slope due to the steam generated from the second cooking object. The process ends when it is indicated that the set voltage higher than the corresponding voltage has been reached.

The rising slope of the input voltage from the sensor due to the steam generated from the first cooking item is larger when a large amount of steam is blown out than when a small amount of steam has seeped out, and is largest in the latter state. (First maximum upward slope). On the other hand, the rising slope (slope) of the input voltage from the sensor due to the steam generated from the second cooking item is approximately constant, and the slope becomes the largest at the time when steam starts to be generated (second maximum rising slope). . The set voltage to be compared with the input voltage from the sensor is lower than the first equivalent voltage corresponding to the first maximum rising slope due to the steam generated from the first food, and the set voltage is lower than the first equivalent voltage corresponding to the first maximum rising slope due to the steam generated from the second food. Since it is higher than the second equivalent voltage corresponding to the maximum rising slope, overheating and underheating of the food to be cooked can be reliably suppressed.

The preventive termination step includes an additional heating time obtained by multiplying the execution time from the start of heating by the microwave source to the end of the first step by a predetermined coefficient, or when the heating time elapses, heating by the microwave source is stopped. and a second step of terminating.

The preventive termination step includes a second step in which an additional heating time is set based on the execution time until the first step is completed, and the second step is terminated when the additional heating time or the manually set heating time elapses. Therefore, it is possible to prevent the user from feeling uncomfortable due to heating for a longer time than the manually set heating time. On the other hand, if the additional heating time is too long, the first cooked food, which has a small volume, may become overheated and cannot be used as a food ingredient, and if the additional heating time is too short, it may become undercooked. Therefore, by setting the additional heating time by multiplying the execution time until the end of the first step by an appropriate coefficient, overheating and underheating of the first food can be effectively suppressed, and an appropriate heating state can be maintained. can get.

The sensor is a steam temperature sensor that detects the temperature of steam, and is disposed on the ceiling wall of the heating chamber.

The sensor is a steam temperature sensor that detects the temperature of steam, and is placed on the ceiling wall of the heating chamber. Therefore, the temperature of the steam generated from the food and flowing upward can be reliably detected.

In the microwave oven of the present invention, it is possible to suppress overheating and underheating of the food at the same time.

FIG. 1 is a perspective view of a microwave oven according to an embodiment of the present invention. FIG. 2 is a sectional view taken along the line II-II in FIG. 1 of the microwave oven with the tray placed and the door closed. A sectional view taken along the line III-III in FIG. 2. Front view of a microwave oven. Flowchart of manual range processing. Flowchart continued from FIG. 5.

Embodiments of the present invention will be described below with reference to the drawings.

1 to 4 show a microwave oven 1 according to an embodiment of the present invention. The X direction in the accompanying drawings is the front-rear direction of the microwave oven 1, with the direction indicated by the arrow being the rear side, and the direction opposite to the arrow being the front side. The Y direction is the width direction of the microwave oven 1, and the direction indicated by the arrow is the left side, and the direction opposite to the arrow is the right side. The Z direction is the height direction of the microwave oven 1, and the direction indicated by the arrow is the upper side, and the direction opposite to the arrow is the lower side.

Referring to FIGS. 1 to 4, the microwave oven 1 includes a microwave oven main body 10, a door 20 attached to the microwave oven main body 10 so as to be openable and closable, and a dedicated tray 28 that is removably arranged in the heating chamber 12. . The microwave oven 1 also includes a magnetron (microwave source) 30, a heater 32, an infrared sensor 34, a thermistor (sensor) 35, an operation panel 40, and a control section 45, as shown most clearly in FIG. The control unit 45 executes the heating process set by operating the operation panel 40, and heats the food C (see FIG. 2) in the heating chamber 12.

Referring to FIGS. 1 to 3, the microwave oven main body 10 includes a heating chamber 12 within a housing 11. As shown in FIG. The heating chamber 12 is a rectangular parallelepiped space with an opening 17 on the front side. The heating chamber 12 is defined by a bottom wall 13, a top wall 14, a pair of side walls 15, a rear wall 16, and a door 20, all of which have a rectangular shape. Among them, the bottom wall 13 is made of a microwave transmitting material such as ceramic, glass, or resin. The top wall 14, the pair of side walls 15, and the rear wall 16 are all made of a metal plate or the like that is a microwave reflector.

Guide rails 18 and 19 for arranging the tray 28 are provided on the pair of side walls 15, respectively. Of these, the upper guide rail 18 is provided in a region above the center of the total height of the heating chamber 12, and the lower guide rail 19 is provided in a region below the center of the total height of the heating chamber 12. Each of the guide rails 18 and 19 is formed by press working so that a part of the side wall 15 bulges into the heating chamber 12 so as to form a right-angled triangular shape, and is provided so as to extend in the front-rear direction.

The door 20 is attached to the front side of the housing 11 and releasably closes the opening 17 of the heating chamber 12. The door 20 is rotatable around a rotation axis (not shown) extending in the width direction between an open position shown in FIG. 1 and a closed position shown in FIG. However, the door 20 may be rotatable around a rotation axis extending in the height direction, and may have any configuration as long as it can open and close the opening 17 of the heating chamber 12.

The door 20 includes a metal, opaque frame 21 that is a microwave reflector, and a window 22 through which the inside of the heating chamber 12 can be seen. As shown most clearly in FIG. 3, the window section 22 includes an inner window 23 that faces the heating chamber 12, and an outer window 24 that is spaced apart from the inner window 23. Both the inner window 23 and the outer window 24 are made of transparent glass or resin that transmits microwaves. A reflective layer 25 is provided between the inner window 23 and the outer window 24, which is made of punched metal and has many holes for ensuring visibility, and is capable of reflecting microwaves.

Referring to FIG. 1, the tray 28 is a rectangular square plate viewed from the height direction, and is selectively and removably disposed on either the upper guide rail 18 or the lower guide rail 19. By arranging the cooking items C on the tray 28, the cooking items C can be placed above the bottom wall 13 of the heating chamber 12 at intervals. The tray 28 of this embodiment is made of a microwave transmitting material such as ceramic, glass, or resin. The widthwise dimension of the tray 28 is smaller than the dimension between the pair of side walls 15 of the heating chamber 12, and the longitudinal dimension of the tray 28 is smaller than the dimension between the rear wall 16 of the heating chamber 12 and the door 20. , are formed to be as large as possible within a range that does not impede placement in the heating chamber 12.

Referring to FIG. 2, the magnetron 30 is disposed between the housing 11 and the heating chamber 12, and heats the food C in the heating chamber 12 using microwaves. More specifically, a metal duct (waveguide) 31 is arranged on the lower surface of the bottom wall 13 of the heating chamber 12, and a magnetron 30 is arranged at the end of this duct 31. An expanded portion 31 a that generally covers the lower surface of the bottom wall 13 of the heating chamber 12 is provided at the end of the duct 31 opposite to the magnetron 30 . A region of the bottom wall 13 surrounded by the expanded portion 31 a constitutes an output portion 13 a that outputs microwaves into the heating chamber 12 .

Referring to FIGS. 2 and 3, the heater 32 is arranged close to the ceiling wall 14 and heats the food C in the heating chamber 12 using radiant heat. In this embodiment, two heaters 32 are arranged at intervals in the front-rear direction, and each heater 32 extends in the width direction from one of the pair of side walls 15 to the other. However, only one heater 32 may be provided so as to be located at the center in the front-rear direction, or three or more heaters 32 may be provided.

The infrared sensor 34 is a monocular thermopile type that includes one infrared detection element and detects the temperature of the food C1 on the bottom wall 13 in the heating chamber 12. The infrared sensor 34 is arranged outside the heating chamber 12 with respect to the upper guide rail 18 formed on the right side wall 15. More specifically, the infrared sensor 34 is disposed below the tray placement section that is the upper end of the upper guide rail 18, and is inserted into the heating chamber through a through hole provided in the center of the upper guide rail 18 in the front-rear direction. It is installed so that it looks inside 12.

The thermistor 35 is a steam temperature sensor that detects the temperature of steam within the heating chamber 12, and is arranged above the ceiling wall 14 outside the heating chamber 12. The thermistor 35 includes a detection section 35a that penetrates the ceiling wall 14 and is disposed inside the heating chamber 12. More specifically, the detection unit 35a is arranged at a corner of the heating chamber 12 defined by the top wall 14, the rear wall 16, and the right side wall 15 in FIG.

Referring to FIG. 4, the operation panel 40 includes three operation sections (input sections) 41 to 43 and one liquid crystal panel 44, and is provided below the window section 22 of the door 20.

The operation unit 41 is made of, for example, a rotary switch, and is provided for manually setting any one of the plurality of heat treatments. The operating section 42 is composed of, for example, a rotary push switch, and is provided for manually setting the details of the heat treatment set by operating the operating section 41 and for starting the heat treatment. The operating section 43 is composed of, for example, a push switch, and is provided for canceling (cancelling) manual settings made by operating the operating sections 41 and 42.

The liquid crystal panel 44 is of a segment display type and includes a number display section 44a capable of displaying a three-digit number. Further, the liquid crystal panel 44 can display characters, arrows, etc. in addition to numbers, and displays the settings made by the operation units 41 and 42 and the execution state of the heat treatment. However, the liquid crystal panel 44 may be of a dot matrix display type, as long as it includes a number display section 44a that displays two or more digit numbers.

Referring to FIG. 2, the control unit 45 includes, for example, one microcomputer, and is electrically connected to the magnetron 30, heater 32, infrared sensor 34, thermistor 35, and operation panel 40.
The control unit 45 executes the heat treatment set by operating the operation panel 40 according to a pre-stored program. The heat treatment can be performed in one of a microwave heating mode in which only the magnetron 30 is controlled until the heating is completed, a heater heating mode in which only the heater 32 is controlled until the heating is completed, and a combined heating mode in which both the magnetron 30 and the heater 32 are controlled. carried out by

More specifically, the control unit 45 selects “oven”, “grill”, “microwave”, “automatic”, “register”, “tray range”, and Execute one of the "unzip" options. In heating processes other than "automatic", the heating time and input power can be set by changing the numerical value on the numerical display section 44a of the liquid crystal panel 44 by operating the operating section 42. In “Auto”, one of a plurality of menus (not shown) can be set by operating the operation unit 42.

Microwave heating (microwave heating treatment), tray microwave (tray microwave heating treatment), and thawing (thawing heating treatment) are performed in microwave heating mode. As shown in FIG. 2, the "microwave" is performed with the food C placed on the bottom wall 13 of the heating chamber 12, and the magnetron 30 is controlled based on the detection results of the infrared sensor 34 and thermistor 35. , the food C is heated by microwaves. The "tray range" is performed with the food C placed on the tray 28 (see FIG. 1) in the heating chamber 12, and the magnetron 30 is heated only based on the detection result of the thermistor 35 without using the infrared sensor The food C is heated using microwaves. "Defrosting" is performed with the food C placed on the bottom wall 13 of the heating chamber 12, and the magnetron 30 is controlled based only on the detection result of the infrared sensor 34, and the food C is heated by microwaves. .

The oven (oven heat treatment) and grill (grill heat treatment) are performed in heater heating mode. "Oven" and "grill" are performed with the food C placed on the tray 28 in the heating chamber 12, and the heater 32 is controlled based only on the detection result of the thermistor 35 without using the infrared sensor 34. Then, the food C is heated by radiant heat.

Regiguri (Regigri heat treatment) is performed in a combined heating mode. "Regigri" is performed with the food C placed on the tray 28 in the heating chamber 12, and the magnetron 30 and heater 32 are controlled based only on the detection results of the thermistor 35 without using the infrared sensor 34. , the food C is heated using microwaves and radiant heat. For example, first, the magnetron 30 is activated to heat the food C to the center, and then the magnetron 30 is stopped and the heater 32 is activated to brown the surface of the food C and achieve the specified temperature. When the heater heating time has elapsed, the operation of the heater 32 is stopped.

Automatic (automatic heating processing) is performed in a heating mode determined according to a manually set cooking menu. Whether to place the food C on the bottom wall 13 or on the tray 28 is determined by the cooking menu. For example, the cooking menu includes ``warming refrigerated rice'' performed in microwave heating mode, ``toast (flipping)'' performed in heater heating mode, and ``deep-fried food 'sakureji'' performed in combined heating mode. ing.

Next, manual microwave heating processing in which the heating time tt is manually set by operating the operating units 41 and 42 will be specifically described.

First, the cooked food C heated in the manual microwave heating process includes a first cooked food C1 that contains a lot of moisture and has a small volume, and a second cooked food C1 that contains more water and has a larger volume than the first cooked food C1. Object C2 is included. Examples of the first cooking item C1 include ingredients such as potatoes and sweet potatoes, and examples of the second cooking item C2 include dishes such as curry and simmered dishes.

Generally, in manual microwave heating processing, the input power (heating amount) by the magnetron 30 is manually set, so it may be set to be the same regardless of the volume of the food C. In this case, the heating amount per unit volume of the first cooking object C1 having a small volume is larger than the heating amount per unit volume of the second cooking object C2 having a large volume. Moreover, the temperature increase gradient of the first cooking object C1 due to heating becomes larger than the temperature increase gradient of the second cooking object C2.

More specifically, the temperature of the first cooking object (for example, potatoes) C1 rises rapidly due to heating, and the amount of steam generated from the first cooking object C1 per unit time is small and gradually oozes out like steam. The state changes from a state where the amount of steam is suddenly ejected in the largest amount (first maximum amount of steam). The rising slope (inclination) of the input voltage Vt(n) from the thermistor 35 due to the steam generated from the first cooking object C1 is larger when a large amount of steam is blown out than when a small amount of steam oozes out. For example, when a small amount of steam oozes from the food C1, the input voltage Vt(n) from the thermistor 35 reaches a third equivalent voltage Vt(n-10)+Vc corresponding to the third temperature increase gradient. In addition, in a state where a large amount of steam is ejected from the food C1, the input voltage Vt(n) from the thermistor 35 is the first equivalent voltage Vt corresponding to the first temperature increase slope having a larger slope than the third temperature increase slope. (n-10)+Va is reached, and thereafter the temperature generally changes at the slope of the first temperature increase gradient. That is, in a state where a large amount of steam is ejected from the food C1, the slope of the temperature increase gradient due to the input voltage Vt(n) from the thermistor 35 becomes the largest (first maximum increase gradient).

On the other hand, the temperature rise of the second cooked item (for example, curry) C2 due to heating is slower than that of the first cooked item C1, and the amount of steam generated from the second cooked item C2 per unit time is lower than that of the first cooked item C1. It always oozes out gradually compared to (second maximum amount of steam). The rising slope (inclination) of the input voltage Vt(n) from the thermistor 35 due to the steam generated from the second food C2 is approximately constant. For example, when 1.5 liters of curry, which is an example of the second food C2, is heated, the input voltage Vt(n) from the thermistor 35 has a slope lower than the first temperature increase slope when steam is generated. The second equivalent voltage Vt(n-10)+Vb corresponding to the small second temperature increase gradient is reached, and thereafter the temperature generally changes at the slope of the second temperature increase gradient. That is, in the case of the second cooking object C2, the slope of the temperature increase gradient of the input voltage Vt(n) from the thermistor 35 becomes the largest (second maximum increase gradient) at the time when steam starts to be generated.

Here, among the first equivalent voltage Vt (n-10) + Va, the second equivalent voltage Vt (n-10) + Vb, and the third equivalent voltage Vt (n-10) + Vc, Vt (n-10) is the thermistor voltage. 35 means the voltage input 10 times ago. Further, Va is a constant term corresponding to the magnitude of variation according to the first temperature increase gradient, Vb is a constant term corresponding to the magnitude of variation according to the second temperature increase gradient, and Vc is a constant term corresponding to the magnitude of variation according to the second temperature increase gradient. This is a constant term corresponding to the magnitude of fluctuation according to the temperature increase gradient. The constant term Va of the first food C1 is larger than the constant term Vb of the second food C2, and the constant term Vc of the first food C1 is greater than or equal to the constant term Vb of the second food C2, for example, the constant term Va is 0.2, the constant term Vb is 0.1, and the constant term Vc is 0.1 (Vb≦Vc<Va).

When a large amount of steam is ejected from the first food C1 and the first temperature rise gradient occurs, the first food C1 is not underheated, but may be overheated. be. When the state of the third temperature increase gradient in which a small amount of steam has oozed out from the first cooking object C1 and the state of the second temperature increase gradient in which steam has oozed out from the second cooking object C2, the first cooking object C1 and the Although the second cooked item C2 is not overheated, the first cooked item C1 and the second cooked item C2 may be underheated. On the other hand, the overheated first cooked item C1 is not suitable as a food ingredient, and the underheated first cooked item C1 and second cooked item C2 are not suitable as either a food ingredient or a dish. Therefore, in this embodiment, based on the above knowledge, the manual microwave heating process by the control unit 45 is configured as follows.

The manual microwave heating process suppresses the normal termination process (steps S5, S10 to S12 shown in FIGS. 5 and 6) that ends when the manually set heating time tt elapses, and overheating and underheating of the food C. (steps S6 to S12 shown in FIGS. 5 and 6).

The preventive termination step sets a time to finish heating the food C by the magnetron 30 based on the detection result of the thermistor 35 corresponding to the actual temperature of the heated food C, and ends before the elapse of the heating time tt. . More specifically, the preventive termination process includes a first step (step S6 in FIG. 5) that ends when the input voltage Vt(n) from the thermistor 35 reaches a predetermined set voltage Vt(n-10)+Vs. , has a second step (step S8 in FIG. 5) that ends when the automatically set additional heating time tc1×α has elapsed. That is, the first step ends when it is shown that the amount of steam per unit time obtained from the detection result of the thermistor 35 has reached the predetermined set amount of steam. However, in the second step, if the total heating time tc obtained by adding the additional heating time tc1×α to the execution time tc1 before setting the additional heating time tc1×α is longer than the manually set heating time tt, the heating time The process ends when tt has elapsed (step S9 in FIG. 5).

Of the set voltage Vt(n-10)+Vs in the first step, Vt(n-10) means the 10th previous input voltage Vt input from the thermistor 35, and Vs is the set temperature increase gradient. This is a constant term that corresponds to the magnitude of the fluctuation. The constant term Vs is smaller than the constant term Va of the first temperature increase gradient (first maximum increase gradient) of the first food C1, and is smaller than the constant term Vc of the third temperature increase gradient of the first food C1 and the second cooking It is larger than the constant term Vb of the second temperature increase gradient (second maximum increase gradient) of the object C2 (Vb≦Vc<Vs<Va). That is, the set voltage of the first step is lower than the first equivalent voltage of the first food C1 and higher than the third equivalent voltage of the first food C1 and the second equivalent voltage of the second food C2. In other words, the set amount of steam is smaller than the first maximum amount of steam, which is the maximum amount of steam generated per unit time from the first food C1, and is the maximum amount of steam generated per unit time from the second food C2. It is more than a certain second maximum amount of steam. Further, the set temperature increase gradient of the first step is gentler than the first temperature increase gradient of the first food C1, and the third temperature increase gradient of the first food C1 and the second temperature rise gradient of the second food C2. It is steeper than the temperature rise gradient.

If the value of the constant term Vs is excessively increased, overheating may occur when the heating object is the first cooking object C1. On the other hand, if the value of the constant term Vs is excessively small, the heating object is the first cooking object C1 and the heating object C1. Any of the second cooking items C2 may be undercooked. Therefore, the value of the constant term Vs is larger than the constant term Vb of the second food C2 and larger than the constant term Vc of the first food C1, for example, higher than 0.1V (not including 0.1V). ), it is preferable to set it to a numerical value range of less than 0.20V, and in this embodiment, it is set to 0.12V. However, the current input voltage Vt(n) is compared with the set voltage Vt(n-10) x k, which is the 10th previous input voltage Vt(n-10) multiplied by a coefficient k according to the set temperature increase slope. It's okay. Further, the current input voltage Vt(n) may be compared with the input voltage Vt(n-5) five times before, and the comparison target can be changed as necessary.

Of the additional heating time tc1×α of the second step, tc1 is the execution time from the start of heating by the magnetron 30 until the end of the first step, and α is a predetermined coefficient. When the object to be heated is the first cooking object C1, an excessively large coefficient α will result in overheating, and an excessively small coefficient α will result in insufficient heating. Therefore, it is preferable to set the coefficient α to a numerical value range of 4.0 or more and 8.0 or less, and in this embodiment, it is set to 6.0.

Next, with reference to FIGS. 5 and 6, the manual microwave heating process performed by the control unit 45 will be described in more detail.

Referring to FIG. 5, in the manual range heating process, the control unit 45 reads the manually set heating time tt in step S1, and then operates the magnetron 30 in step S2. Subsequently, in step S3, the thermistor 35 starts intermittent detection (for example, every second) of the voltage Vt(n), and then in step S4, the counter starts measuring the total heating time tc by the magnetron 30.

Next, in step S5, it is determined whether the total heating time tc has reached the set heating time tt. Then, if the total heating time tc has not reached the heating time tt, the process proceeds to step S6, and if the total heating time tc has reached the heating time tt, the process proceeds to step S10.

In step S6, it is determined whether the input voltage Vt(n) from the thermistor 35 is equal to or higher than the set voltage Vt(n-10)+Vs. Then, if the input voltage Vt(n) is less than the set voltage Vt(n-10)+Vs, the process returns to step S5, and if the input voltage Vt(n) is equal to or higher than the set voltage Vt(n-10)+Vs, the process returns to step S5. Proceed to S7. Here, the constant term Vs is smaller than the constant term Va of the first temperature increase gradient of the first food C1 and larger than the constant term Vb of the second temperature increase gradient of the second food C2. Therefore, when the cooking item C is the first cooking item C1 such as a potato, the process proceeds to step S7, and the preventive termination step is executed. On the other hand, if the food C is a second food C2 such as curry, steps S5 and S6 are repeated until the heating time tt elapses without proceeding to step S7.

In step S7, after storing the execution time tc1 until the condition of step S6 is satisfied, in step S8, it is determined whether the total heating time tc is equal to or longer than the execution time tc1 plus the additional heating time tc1×α. That is, it is determined whether the additional heating time tc1×α has elapsed after the condition in step S6 is satisfied. Then, if the additional heating time tc1×α has not elapsed, the process proceeds to step S9, and if the additional heating time tc1×α has elapsed, the process proceeds to step S10.

In step S9, it is determined whether the total heating time tc has reached the set heating time tt. Then, if the total heating time tc has not reached the heating time tt, the process returns to step S8, and if the total heating time tc has reached the heating time tt, the process proceeds to step S10.

When the total heating time tc reaches the heating time tt in steps S5 and 9, and when the additional heating time tc1×α has elapsed in step 8, as shown in FIG. 6, the operation of the magnetron 30 is stopped in step S10. do. Subsequently, in step S11, the intermittent detection of the voltage Vt by the thermistor 35 is stopped, and in step S12, the measurement of the total heating time tc by the counter is stopped, and the process returns.

The microwave oven 1 configured as described above has the following features.

The manual microwave heating process has a normal end step (step S5) that ends when the manually set heating time tt has elapsed, and a preventive end step (steps S6 to S9) that ends before the elapse of the heating time tt, The prevention end step includes a first step (step S6) that ends when the detection result of the thermistor 35 indicates that the amount of steam per unit time has reached the set amount of steam. In this way, the preventive termination process is performed based on the detection result of the thermistor 35 that detects the steam generated from the food C, that is, the actual heating state of the food C, rather than the weight of the food C. Moreover, since the set steam amount to be compared with the steam amount obtained from the detection result of the thermistor 35 is lower than the first maximum steam amount, which is the maximum amount of steam generated per unit time from the first cooking object C1, the first cooking Since the heating state before a large amount of steam is generated from the object C1 (overheating occurs), that is, a small amount of steam exuding from the first object C1, can be detected, overheating of the first object C1 can be suppressed. In addition, since the set amount of steam is higher than the second maximum amount of steam, which is the maximum amount of steam generated per unit time from the second cooking object C2, even if steam is generated from the second cooking object C2, the prevention termination process is not performed. does not shift and is heated until the manually set heating time tt, so it is possible to suppress insufficient heating of the second food C2. In other words, it is possible to suppress overheating and underheating of the food C at the same time.

More specifically, the rising slope (slope) of the input voltage Vt(n) from the thermistor 35 due to the steam generated from the first cooking object C1 is greater than the state in which a small amount of steam has oozed out (third temperature rising gradient). The state where a large amount of steam is ejected (first temperature increase gradient) is larger, and the latter state is the largest (first maximum temperature increase gradient). On the other hand, the rising slope (slope) of the input voltage Vt(n) from the thermistor 35 due to the steam generated from the second cooking object C2 is approximately constant, and the slope becomes maximum at the time when steam starts to be generated ( second maximum upward slope). The set voltage Vt(n-10)+Vs compared with the input voltage Vt(n) from the thermistor 35 corresponds to the first temperature increase gradient (first maximum increase gradient) due to the steam generated from the first cooking object C1. The second equivalent voltage Vt(n-10)+Va is lower than the first equivalent voltage Vt(n-10)+Va and corresponds to the second temperature increase gradient (second maximum increase gradient) due to the steam generated from the second cooking object C2. )+Vb, overheating and underheating of the food can be reliably suppressed.

In the prevention termination step, an additional heating time tc1×α is set based on the execution time tc1 until the first step (step S6) is completed, and the additional heating time tc1×α or the manually set heating time tt elapses. It includes a second step (steps S7, 8) that ends. Therefore, it is possible to prevent the user from feeling uncomfortable due to heating the food C for a longer time than the manually set heating time tt. On the other hand, if the additional heating time tc1×α is too long, the first cooking product C1 having a small volume may become overheated and cannot be used as a food ingredient. This may result in underheating that is inappropriate for use. Therefore, by setting the additional heating time tc1×α, which is the execution time tc1 of the first step multiplied by an appropriate coefficient α, overheating and underheating of the first food C1 can be effectively suppressed, and appropriate heating can be achieved. The state is obtained.

A thermistor 35 that detects the temperature of the steam is arranged on the ceiling wall of the heating chamber 12. Therefore, the temperature of the steam generated from the food C and flowing upward can be reliably detected.

Note that the present invention is not limited to the configuration of the embodiment described above, and various changes are possible.

For example, the sensor may be a humidity sensor, and as long as it is configured to be able to detect steam generated from the food C, it can be changed as necessary. Further, as the detection result of the sensor, a current value or a digital value may be used, or the positive and negative values may be reversed. The first step of the prevention termination step may be configured to end when it is indicated that the amount of steam per unit time obtained from the detection result of the sensor has reached a predetermined set amount of steam. Further, the set amount of steam is smaller than the first maximum amount of steam, which is the maximum amount of steam generated per unit time from the first food C1, and is the maximum amount of steam generated per unit time from the second food C2. It is sufficient if the value is set to be larger than the second maximum steam amount.

The additional heating time tc1×α may be set to be equal to or less than the manually set heating time tt, and the manual range heating process by the control unit 45 may be configured without step S9 shown in FIG. 5.

The microwave oven 1 does not need to include the infrared sensor 34 that detects the temperature of the food C to be cooked.

The microwave oven 1 may be capable of executing only the microwave heating mode without being provided with the heater 32.

1 Microwave oven 10 Microwave oven body 11 Housing 12 Heating chamber 13 Bottom wall 13a Output section 14 Top wall 15 Side wall 15a Vent 16 Rear wall 17 Opening 18 Upper guide rail 19 Lower guide rail 20 Door 21 Frame 22 Window section 23 Inner window 24 Outer window 25 Reflection layer 28 Tray 30 Magnetron (microwave source)
31 Duct 31a Expanded section 32 Heater 35 Thermistor (sensor)
35a Detection section 40 Operation panel 41-43 Operation section 44 Liquid crystal panel 44a Numerical display section 45 Control section C Food to be cooked

Claims (4)

a heating chamber for heating food;
a microwave source that outputs microwaves that heat the food;
a sensor for detecting steam generated from the cooking food;
a control unit that outputs microwaves from the microwave source to heat-process the food based on a manually set heating time;
The cooked food includes a first cooked food and a second cooked food that has a larger volume and more moisture than the first cooked food,
The heat treatment by the control unit includes a normal termination step that ends when the heating time elapses, and a preventive termination step that ends before the heating time elapses,
In the prevention termination step, the amount of steam per unit time obtained from the detection result of the sensor is smaller than the first maximum amount of steam that is the maximum amount of steam generated per unit time from the first cooking object, and 2. A microwave oven comprising a first step that ends when it is indicated that a set amount of steam has been reached that is greater than a second maximum amount of steam that is the maximum amount of steam generated per unit time from two foods to be cooked. The control unit determines the amount of steam based on the input voltage from the sensor,
In the first step, the input voltage from the sensor is lower than a first equivalent voltage corresponding to a first maximum rising slope due to the steam generated from the first cooking object, and the input voltage is lower than the first maximum rising slope. 2. The microwave oven according to claim 1, wherein the microwave oven is terminated when a set voltage higher than a second equivalent voltage corresponding to a second maximum rising slope by steam generated from the second cooking object is reached. The preventive termination step includes an additional heating time obtained by multiplying the execution time from the start of heating by the microwave source to the end of the first step by a predetermined coefficient, or when the heating time elapses, heating by the microwave source is stopped. 3. A microwave oven according to claim 1 or 2, comprising a second step of terminating. The microwave oven according to claim 1 or 2, wherein the sensor is a steam temperature sensor that detects the temperature of steam, and is disposed on a ceiling wall of the heating chamber.

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