CN102802294A - High frequency heating device - Google Patents

Abstract

The invention provides a high frequency heating device which can work safely during the abnormal heating through detecting the temperature and the steam quantity of a heating chamber and can prevent the early power off in the normal heating. The high frequency heating device can determine the size of food (S106A to S106D), and can detect the abnormal heating of food according to the size of food (small size 1, small size 2, small size 3, and big size) and the time (S108A to S108C) spent on making the steam quantity in the heating chamber exceed a set value, reduce the level of the high frequency output of a magnetron, and decide the working time after the detection.

Description

High frequency heating device

technical field

The present invention relates to a high-frequency heating device in consideration of safety.

Background technique

Conventionally, in high-frequency heating devices such as microwave ovens, measures have been taken against abnormal heating caused by misuse by users to ensure safety. For example, conventionally, when the surface temperature of the food in the heating chamber reaches a predetermined value or more, the size of the food is estimated based on the rise time of the atmospheric temperature in the heating chamber, and the size of the food is divided into the case of a small load and the case of a large load. Setting a threshold value for lowering the output level of the high-frequency generating unit prevents abnormal heating even during heating of a small load (for example, refer to Patent Document 1).

In addition, a technique has been proposed that prevents abnormal heating of a small amount of food by stopping the high-frequency generating means when the amount of steam in the heating chamber is below a predetermined value when the amount of food is small.

[Patent Document 1] Japanese Patent Laid-Open No. 2009-127924

With the high-frequency heating device described in Patent Document 1, when the user heats a small amount of food, even if the heating power is set to be large and the heating time is set to be long by mistake to start heating If it is detected that the temperature of the atmosphere in the heating chamber rises and it is determined that the temperature of the food in the heating chamber has reached a high temperature, the heating power is reduced so that the heating does not proceed further, thereby preventing abnormal heating of the food.

However, when using the heating sheet to heat the frozen food, although the heating sheet reaches a high temperature after the heating, the heating power will not be reduced before the rise of the atmospheric temperature in the heating chamber is detected, so although the power will not be cut off in advance to cause Heating is completed in a frozen state, but for a small amount of food whose temperature tends to rise, there is a problem that the food is abnormally heated and the temperature rises rapidly.

In addition, for a high-frequency heating device that detects the amount of steam in the heating chamber to control the operation of the high-frequency generating unit, even for a small amount of food whose temperature tends to rise, the steam generation in the heating chamber does not stop until the amount of steam in the heating chamber becomes below a specified value. High frequency, will not cause premature power failure, and can prevent overheating of food and stop working safely.

However, in the high-frequency heating device described in Patent Document 1, when the signal noise level of the steam detection unit is large, even if the steam amount is below a predetermined value, a signal is detected, and a decrease in the steam amount cannot be detected. There is no way to stop working when abnormally heated. Furthermore, there is a problem that even if the amount of steam from the food is reduced, it takes time for the steam in the heating chamber to be discharged to the outside of the heating chamber to reduce the amount of residual steam, and the food is abnormally heated during this period.

Contents of the invention

The present invention has been made in view of the above-mentioned conventional problems, and its object is to provide a high-frequency heating device that does not cause premature power failure during normal heating, and even when abnormal heating occurs, by detecting The temperature and the amount of steam can also reduce the output level of the high-frequency generating unit and work safely.

In order to solve the above-mentioned conventional problems, the high-frequency heating device of the present invention has: a heating chamber for accommodating food; a high-frequency generating unit that generates high-frequency for inductively heating food in the heating chamber; and a surface temperature detecting unit that It is arranged outside the wall of the heating chamber and detects the temperature of the food in the heating chamber in a non-contact manner; the temperature detection unit in the warehouse detects the temperature of the atmosphere in the heating chamber; the steam detection unit in the warehouse detects the temperature of the food in the heating chamber. the amount of steam in the heating chamber; and a control unit that controls the output of the high-frequency generating unit based on the outputs from the surface temperature detection unit, the temperature detection unit in the chamber, and the steam detection unit in the chamber. When the user sets an arbitrary time and inputs a heating start operation, the control unit estimates the size of the food based on the rise time of the ambient temperature in the heating chamber, and estimates the size of the food based on the amount of steam in the heating chamber reaching a predetermined value or more. According to the estimated size of the food, the output level of the high-frequency generating unit is reduced to determine the time before stopping the work, and the work is stopped safely.

According to the above structure, even if the user starts heating by mistakenly setting a large heating power and a long heating time when heating a small amount of food, when the temperature of the atmosphere in the heating chamber rises, the user starts heating. When it is determined that the temperature of the food has reached a high temperature due to the increase in the amount of steam, the heating power is reduced and the operation is stopped so that the heating does not proceed further, so that abnormal heating of the food can also be prevented. In addition, the heating power is not lowered until an increase in the temperature of the atmosphere in the heating chamber and an increase in the amount of steam in the heating chamber are detected to determine abnormal heating, so that no premature power failure occurs during normal heating.

According to the present invention, it is possible to provide a high-frequency heating device as follows: when manually heating a small amount of food, the high-frequency heating device does not cause premature power failure during normal heating, prevents abnormal heating, and is safe and reliable. high.

Description of drawings

Fig. 1 is a system schematic diagram of a high-frequency heating device according to an embodiment of the present invention.

Fig. 2 is a front view showing a state in which an opening and closing door of the high-frequency heating device is closed.

FIG. 3 is a block diagram showing an electrical configuration of a control unit.

FIG. 4 is a flowchart showing the control content of the infrared sensor of the control unit.

FIG. 5 is a flowchart showing the control content of the steam sensor of the control unit.

Symbol Description

1 heating chamber

5 infrared sensor (surface temperature detection unit)

7 Heating chamber thermistor (temperature detection unit in the chamber)

8 steam sensor (steam volume detection unit in the warehouse)

11 Magnetron (high frequency generating unit)

12 control department

Detailed ways

A first aspect provides a high-frequency heating device including: a heating chamber for storing food; a high-frequency generating unit that generates high-frequency for inductively heating food in the heating chamber; and surface temperature detection. A unit, which is arranged outside the wall of the heating chamber, detects the temperature of the food in the heating chamber in a non-contact manner; a temperature detection unit in the chamber, which detects the temperature of the atmosphere in the heating chamber; a steam detection unit in the chamber, which Detecting the amount of steam in the heating chamber; and a control section that controls the output of the high-frequency generating unit based on the outputs from the surface temperature detecting unit, the internal temperature detecting unit, and the internal steam detecting unit , when the user sets an arbitrary time and inputs a heating start operation, the control unit estimates the size of the food in the heating chamber, and detects it based on the time elapsed since the amount of steam in the heating chamber reaches a predetermined value or more. In the case of abnormal heating of food, the output level of the high-frequency generating unit is lowered, and the time from the stop of the high-frequency generating unit is obtained, thereby preventing premature power failure during normal heating and preventing damage to the food. Unusual heating of small quantities of food during manual cooking.

According to the second aspect, especially in the first aspect, when the user sets an arbitrary time and inputs a heating start operation, the size of the food is estimated based on the rise time of the atmospheric temperature in the heating chamber, and the size of the food is estimated based on the When abnormal heating of food is detected during the time elapsed since the amount of steam in the heating chamber has reached a predetermined value or more, the output level of the high-frequency generating unit is lowered, and the time until the high-frequency generating unit stops is obtained, thereby , There will be no early power failure during normal heating, and it can prevent abnormal heating when a small amount of food is manually cooked.

According to the third aspect, particularly in the first or second aspect, the interior temperature detection unit is integrated with the interior steam detection unit, thereby reducing the number of components and simplifying the structure.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to this embodiment.

FIG. 1 is a schematic diagram of a high-frequency heating device system according to Embodiment 1 of the present invention.

In Fig. 1, the bottom surface of the heating chamber 1 is inserted with a tray 2 which is obtained by cutting the crystallized glass as the bottom surface of the heating chamber according to the size of the heating chamber. On the tray 2, food 3 is placed, facing the heating chamber 1, on the right side. A hole 4 for temperature detection is opened on the right side surface in the heating chamber 1 on the side, and an infrared sensor 5 (surface temperature detection unit) arranged outside the wall surface is arranged at a position facing the hole 4 .

Infrared sensor 5 detects the surface temperature of food 3 in heating chamber 1 in a non-contact manner. An upper heater 6 is arranged on the upper part of the heating chamber 1, and has a heating chamber thermistor 7 (in-chamber temperature detection unit) for detecting the temperature in the heating chamber 1 and a steam sensor 8 for detecting the amount of steam in the heating chamber 1 (Steam detection unit in the warehouse). In the embodiment of the present invention, the heating chamber thermistor 7 and the steam sensor 8 are used as one sensor having both functions in combination.

A water storage part 10 is arranged at the lower back side of the heating chamber 1, and water is supplied from a nozzle 9 protruding from a side wall of the heating chamber 1, and the water is boiled to generate steam. Outside the heating chamber 1, there are a magnetron 11 (high-frequency generating unit) that generates and outputs high frequencies, and a control unit 12 that performs heating control of the high-frequency heating device, and the like.

The control unit 12 is mainly composed of a microcomputer, and performs A/D conversion on the signal voltage obtained from the infrared sensor 5, the signal voltage obtained from the heating chamber thermistor 7 and the steam sensor 8, and the A/D converted The temperature data of the food 3 is compared with the predetermined judgment value of the finished product temperature of the food 3, the heating time of the food 3 is determined, and the output from the magnetron 11 is controlled.

Fig. 2 is a front view showing a state in which a door of a high-frequency heating device described later is closed. In the front of the heating chamber 1, a door 13 is provided in an openable and closable manner, and on the door 13, a cross key 14 for the user to select the heating menu and the selection of the heating time, etc., and to perform selection and heating are provided. A start button 15 for starting operations, etc., and a manual button 16 for canceling or returning operations, and a display unit 17 for performing necessary displays are provided.

FIG. 3 is a block diagram showing an electrical configuration of the control unit 12 .

In Fig. 3, the control unit 12 is inputted from the cross key 14, the start button 15, the manual button 16 (they are collectively referred to as operation keys), the infrared sensor 5, the heating chamber thermistor 7 detecting the temperature in the heating chamber 1, The signal of each structure of the steam sensor 8 which detects the amount of steam. Then, the control unit 12 displays information on the output power and heating time on the display 17 in accordance with a pre-stored program based on these signals.

Moreover, the control unit 12 controls the magnetron 11, the upper heater 6, the rear heater 18, the circulation fan 19 sending hot air from the rear heater 18 into the heating chamber 1, and the steam heater 20 via the drive circuit 18. , the operation of the cooling fan 21 for cooling the heat generated by the magnetron 11 and the electrical components. Since the operation of the magnetron 11 is controlled via the inverter 22, the output can be controlled, for example, the steam heater 20 and the high-frequency output 300W can be used simultaneously.

FIG. 4 is a flowchart showing the control content of the infrared sensor 5 of the control unit 12 , and FIG. 5 is a flowchart showing the control content of the steam sensor 8 of the control unit 12 .

In the present embodiment, when the user sets an arbitrary time and inputs the high-frequency heating start operation, the abnormal heating preventing means realized by the infrared sensor 5 and the abnormal heating preventing means realized by the steam sensor 8 are parallelized. Work. The infrared sensor 5 is placed in the atmosphere of the heating chamber 1 through the hole 4 for temperature detection on the right side of the heating chamber 1 in FIG. 1 . Therefore, when heating, the lens of the infrared sensor 5 may become dirty due to the scattering of oil or seasoning from the food 3, and the surface temperature of the food 3 cannot be accurately read, causing the food 3 to fall into an abnormal heating state. In this case, abnormal heating of the food 3 can also be prevented by operating the abnormal heating prevention means realized by the steam sensor 8 in parallel.

First, the control content of the infrared sensor 5 is demonstrated using FIG. 4. FIG.

When the user heats the food 3, the output power of high-frequency heating is selected by clicking "range output switching" with the cross key 14 (step S1). In the high-frequency heating device of this embodiment, 600W is selected when pressing it for the first time, and then 800W, 500W, 300W, 300W steam, and 150W can be selected sequentially by clicking. 300W steam is a combination of high frequency output and steam. Here, it is assumed that a high-frequency output of 600W is selected.

Next, the cooking time is selected with the cross key 14 (step S2). Regarding the cooking time, the maximum time is determined respectively according to the output power of the high-frequency output. In the high-frequency heating device of this embodiment, it is 6 minutes at 800W. And, it is 30 minutes at 600W, 500W, and 300W, 15 minutes at 300W steam, and 300 minutes at 150W. Here, it is assumed that the maximum time of 600W, that is, 30 minutes is selected.

Next, the user presses the "start" key provided at the center of the cross key 14 to start heating (step S3). After the heating starts, the temperature of the food 3 rises by the high-frequency output, and the level of the heating chamber thermistor 7 located in the heating chamber 1 rises. The level of the thermistor can be converted to temperature as a function of the temperature in the center of the heating chamber 1 . Also, the level of the steam sensor explained below can be converted to the amount of steam.

In FIG. 4 , when the level of the heating chamber thermistor rises by T steps from the initial heating chamber thermistor level before heating (step S4 ), let the rising time be A[s] (step S5 ). In this embodiment, the class T of the thermistor is 15 classes, and the rising time A when heating one potato is 132 [s]. Also, class 15 of the thermistor scale corresponds to about 60°C. In addition, when the rise time A is Tw [s] or less, it is a small amount (step S6A), and when it exceeds Tw [s], it is a large amount (step S6B). In this embodiment, Tw=240[s].

In step S6, when there is a small amount of food 3, the detection temperature of the infrared sensor 5 (referred to as IR detection temperature) and the threshold temperature for a small load (referred to as power reduction temperature, in this embodiment, set is 92°C) for comparison (step S7). As a result of the comparison, when the IR detection temperature is equal to or higher than the threshold temperature, the output of the magnetron as the high-frequency generating means is lowered to alleviate heating (step S8). On the other hand, when the result of the comparison is that the IR detection temperature is lower than the threshold temperature, it is determined whether the heating time has reached the set cooking time (step S11).

Then, in step S8, the high-frequency output of the magnetron is lowered, and after a predetermined time has elapsed, the temperature detected by the infrared sensor 5 is compared with the first abnormal heating temperature (98° C.) again (step S9). When the IR detection temperature is higher than the first abnormal heating temperature, after a predetermined time has elapsed, it is compared with the second abnormal heating temperature (92°C). If the IR detection temperature is higher than the second abnormal heating temperature, the magnetization is stopped. Control (S10), when the IR detection temperature is lower than the second abnormal heating temperature, heating is performed with the reduced output state until the cooking time ends (step S11).

Next, the content of control of the steam sensor 8 according to the embodiment of the present invention will be described using FIG. 5 . In addition, steps S1 to S5 are the same as the control content of the infrared sensor 5 in FIG. 4 .

When the rising time A[s] is less than or equal to Tw1[s], the heated object is defined as the minimum amount of 1 (step S106A). When it is greater than Tw1[s] and less than or equal to Tw2[s], let it be a small amount of 2 (step S106B). When it is greater than Tw2[s] and equal to or less than Tw3[s], let it be a small amount of 3 (step S106C). The size of the food 3 is such that a small amount 1<a small amount 2<a small amount 3, and when it is larger than Tw3[s], it is a large amount (step S106D). Suppose a small amount of 1 is 50g of sweet potatoes, a small amount of 2 is 1 potato, a small amount of 3 is 2 potatoes, and a large amount is more load. Although a small amount is divided into three levels in the present embodiment, it may be divided into any number of levels.

In addition, in the present embodiment, when an output power of 600W is selected, Tw1=110[s], Tw2=210[s], and Tw3=270[s]. In many cases, it is assumed that there is no dangerous load without causing smoke or fire of the food 3 even if the heating is continued at the maximum time of each output. In this embodiment, when one potato is heated with 600W, A is 135 [s].

In addition, from the beginning of heating (step S3), the steam sensor 8 located at the right side of the heating chamber 1 is used to monitor the amount of steam in the heating chamber 1, and the food 3 is subjected to high-frequency heating to generate steam. When the level of the steam sensor 8 is When the predetermined value or more is maintained for a predetermined time, it is assumed that steam is detected (steps S107A, S107B, and S107C). In this embodiment, when the level 175 or higher is maintained for 0.6 [ms], it is defined as "steam detected by the steam sensor". In addition, let the time from the start of heating that the steam is detected by the steam sensor be B[s] (steps S108A, S108B, S108C). In this embodiment, when one potato is heated with 600W, B is 133 [s].

Then, heating (B+a)[s] is continued in the state of initial setting output (step S109A, S109B, S109C), and it transfers to the next step. In this embodiment, a=120[s]. Thus, when heating one potato with 600W, the heating is continued for 133+120=253 [s].

Next, it is determined whether or not the level of the thermistor in the heating chamber has risen by the Tc level since the start of heating (step S3) (steps S110A, S110B, S110C). This step is put into the program in order to prevent the food 3 from being powered off in advance. Although the output power is reduced in the next step, it is necessary to avoid reducing the output when the temperature of the food 3 has not yet risen. Therefore, if the temperature of the food 3 has not risen sufficiently, the next step is not transferred.

However, when the setting level of the heating chamber thermistor 7 is increased excessively, when the temperature of the heating chamber 1 at the beginning is high, although the food 3 is heated and the temperature of the food 3 rises, the temperature of the food 3 will rise due to the heating chamber thermal sensitivity. Since the level of resistance rises slightly from the initial stage of the heating chamber 1, the food 3 may fall into a dangerous state because the heating continues even though the temperature of the food 3 rises sufficiently. Here, in the present embodiment, it is assumed that the thermistor class Tc=17 classes.

Next, the output power is lowered from the initial output to c1 [W] (steps S111A, S111B, S111C). In the present embodiment, the output is lowered from 600 [W] to 300 [W] from the initial setting. The heating times in the state where the power is reduced are (B+a)×b1 [s], (B+a)×b2 [s], and (B+a)×b3 [s], respectively. These b1, b2, and b3 are constants, and are different for small amounts of 1, 2, and 3. In the present embodiment, the case of heating one potato with 600W is classified as a small amount of 2, and b2=2, so the power reduction output of (133+120)×2=506 [s] is maintained.

Next, it shifts to the intermittent operation of c2 [W] (steps S112A, S112B, S112C). In this embodiment, 300 [W], 5 [s] on/10 [s] off intermittent operation is set. Let the heating times be (B+a)×d1[s], (B+a)×d2[s], and (B+a)×d3[s], respectively. These d1, d2, and d3 are constants, and are different for a small amount of 1, a small amount of 2, and a small amount of 3. In the present embodiment, the case of heating one potato with 600W is classified as a small amount of 2, and the constant d2=1, so the intermittent operation of (133+120)×1=253 [s] is maintained.

And when the heating time of step S112A, S112B, S112C ends, high-frequency output is stopped (step S113). In many cases, the initial setting output is maintained, and when the heating for the set time ends, the cooking time ends (step S114), and the output of the magnetron 11 is stopped. In this embodiment, in the case of heating one potato with a high-frequency output of 600W, normally, it only takes 4[min]=240[s] to reach an appropriate state. However, if the user mistakenly When the heating time is set to 30 minutes, the high-frequency output is 600W for 253[s], 300W for 506[s], and 300W for 253[s] intermittently, and the total heating time is 1012[s]. It will be in a raw state without smoke, and the high frequency output will be stopped safely.

As described above, even when the user starts heating by mistakenly setting the heating power and heating time, the temperature rise and the amount of steam in the heating chamber 1 are detected to be higher than that in the case of heating the normal food 3 . temperature, thereby lowering the level of high-frequency output, and calculating the time until the high-frequency stop, thereby preventing abnormal heating of the food 3 and making it safe to use.

As mentioned above, according to the high-frequency heating device of the present invention, even if the user sets a large heating power and a long heating time for a small amount of food, there will be no early power-off during normal heating, Abnormal heating can be prevented, and a safe, high-reliability high-frequency heating device can be provided.

Claims (3)

1. a thermatron is characterized in that, this thermatron has:

Take in the heating chamber of food;

The high frequency generation unit, its generation is used for the food in the said heating chamber is carried out the high frequency of induction heating;

The surface temperature detecting unit, it is configured in the wall outside of said heating chamber, detects the temperature of the food in the said heating chamber with the noncontact mode;

Temperature detecting unit in the storehouse, it detects the atmosphere temperature in the said heating chamber;

Steam detecting unit in the storehouse, it detects the quantity of steam in the said heating chamber; And

Control part, it controls the output of said high frequency generation unit according to the output from steam detecting unit in temperature detecting unit and the said storehouse in said surface temperature detecting unit, the said storehouse,

When the user has set random time and imported heating when beginning to operate; Said control part detects reaching setting above institute elapsed time based on the quantity of steam in the said heating chamber under the situation of unusual heating of food; Reduce the output rank of said high frequency generation unit, and obtain the time that stops apart from said high frequency generation unit.

2. thermatron according to claim 1, wherein,

When the user has set random time and imported heating when beginning to operate; Said control part is inferred the size of food according to the rise time of the atmosphere temperature in the said heating chamber; Detect reaching setting above institute elapsed time under the situation of unusual heating of food based on the quantity of steam in the said heating chamber; Reduce the output rank of said high frequency generation unit, and obtain the time that stops apart from said high frequency generation unit.

3. thermatron according to claim 1 and 2, wherein,

In the said storehouse in temperature detecting unit and the said storehouse steam detecting unit be one.

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