JP5066111B2 - High frequency heating device - Google Patents

Description

  The present invention relates to a high-frequency heating apparatus that heats food with a high-frequency output.

  In this type of conventional heating apparatus, the customer can set the high-frequency output and the heating time for heating the food by operating the operation unit arranged on the front surface of the cooker body. ing.

  As described above, in the cooking method in which the customer can set the high frequency output and the heating time, the customer may set a time significantly longer than the heating time suitable for the weight of the food. In this case, the food is heated. The magnetron may be overburdened, or the food itself may smoke or ignite due to overheating of the food.

  Therefore, conventionally, even if the customer sets a time significantly longer than the heating time suitable for the weight of the food, a method of preventing the temperature rise of the magnetron that heats the food or a method of preventing the smoke or ignition of the food is taken. The following are known as such methods.

  The high-frequency heating device shown in Patent Document 1 controls the maximum output of high-frequency energy (high-frequency output) according to the weight of the object to be heated, stabilizes the oscillation of the magnetron, and prevents an abnormal temperature rise or electric field concentration. It is a thing.

  According to the size and type of the object to be heated, the maximum output of the high frequency energy is reduced when the weight of the object to be heated is small, and the maximum output of the high frequency energy is increased when the weight of the object to be heated is large. When impedance matching is not achieved, the microwave is reflected and returns from the waveguide toward the magnetron, so that the oscillation of the magnetron becomes unstable and abnormal temperature rise and electric field concentration are prevented.

  In addition, in the microwave oven shown in Patent Document 2, when the cook mistakenly operates the timer of the operation unit and sets a time that is significantly longer than the heating time suitable for the weight of the food, the food itself is overheated due to overheating. It prevents smoke and fire.

  As for the contents, when the heating time TM input by the cooker's timer operation is longer than the heating time TO obtained based on the weight of the food, by performing the cooking operation with the heating time TO as the actual heating time, Even if the customer sets a time significantly longer than the heating time suitable for the weight of the food, the food itself is prevented from being smoked or ignited due to overheating of the food.

JP-A-3-2013388 Japanese Patent Laid-Open No. 9-213472

  In Patent Document 1 and Patent Document 2 described above, the object to be heated is heated under conditions different from the setting conditions input by the customer.

  For example, in Patent Document 1, the maximum output of high-frequency energy (high-frequency output) is controlled according to the weight of food to be heated, and in Patent Document 2, the upper limit of the heating time is determined according to the weight of food to be heated. End up.

  In these cases, the heating is controlled on the cooker body side against the customer's intention, and the heating will be completed in a time shorter than the time set by the customer. The problem arises.

  The present invention has been made to solve the above-described problems. In claim 1, the heating chamber for heating the food, the table plate placed on the bottom surface of the heating chamber, and the table plate are supported. Weight detecting means for detecting the weight of the food placed on the table plate, a magnetron for heating the food with a high frequency output, an inverter power supply capable of changing the high frequency output of the magnetron, and heating the food In the high-frequency heating apparatus including a high-frequency output for the operation and an operation unit for setting a heating time, a maximum energization allowable time for each high-frequency output according to the weight of the food detected by the weight detection unit is calculated, and the operation If the heating time of the food set in the section is longer than the maximum permissible energization time, the high frequency output is reduced after the maximum energization permissible time has elapsed, and the food Those having a control means for heating.

  In Claim 2, when the heating time of the food set by the operation unit is longer than the maximum allowable energization time, the control means reduces the high-frequency output stepwise after the maximum allowable energization time has elapsed. Is to heat.

  According to the present invention, even if the customer sets a time significantly longer than the heating time suitable for the weight of the food, the heating ends at the heating time set by the customer. In this case, the temperature of the magnetron can be prevented from rising, and the food can be prevented from being smoked or ignited, and the safety of the cooker body can be ensured to give the customer a sense of security.

It is the perspective view which looked at the main body of the heating cooker of one Example from the front side. It is AA sectional drawing of FIG. It is a perspective view of the state which opened the door of the heating cooker of one Example, and was able to see the inside of a main body. It is sectional drawing which shows schematic structure of the weight detection means of the heating cooker. It is explanatory drawing explaining the rotation antenna and weight detection means of the heating chamber bottom face of the heating cooker. It is a block diagram for demonstrating the control circuit of the heating cooker. It is explanatory drawing which shows a high frequency output and maximum energization allowable time according to the weight of food.

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

  1 to 3 show the main part of the present embodiment. FIG. 1 is a perspective view of the main body of the cooking device as seen from the front side, FIG. 2 is a cross-sectional view taken along the line A-A in FIG. It is a perspective view of the state which removed the outer frame of a cooking appliance main body, opened a door, and can see the inside of a main body.

  In the figure, the main body 1 of the heating cooker puts food to be heated in a heating chamber 28 and heats the food using high frequency or heat from a heater.

  The door 2 opens and closes to put food in and out of the heating chamber 28. By closing the door 2, the heating chamber 28 is hermetically sealed to prevent leakage of high frequency used when the food is heated. It is possible to contain the heat and efficiently heat it.

  The handle 9 is attached to the door 2 and facilitates opening and closing of the door 2, and has a shape that can be easily grasped by a hand.

  The glass window 3 is attached to the door 2 so that the state of food being cooked can be confirmed, and uses glass that can withstand high temperatures due to heat generated by a heater or the like.

  The input means 71 is provided on the operation panel 4 below the front surface of the door 2 and has an operation section 6 for inputting a heating means such as high-frequency heating or heater heating, a high-frequency output or heating time as heating intensity, It is comprised with the display part 5 which displays the content input from the operation part 6, and the progress state of cooking. The input means 71 is provided on the operation panel 4 when the operation panel 4 is provided on either the left or right side of the front surface of the door 2.

  The outer frame 7 is a cabinet that covers the upper surface and the left and right side surfaces of the main body 1 of the heating cooker.

  The rear plate 10 forms the rear surface of the cabinet described above. An external exhaust duct 18 is attached to the upper portion of the rear plate 10, and steam exhausted from food and internal components of the main body 1 are installed inside the external exhaust duct 18. An exhaust hole 36 for discharging cooling air (waste heat) 39 after cooling is provided.

  The external exhaust duct 18 discharges the cooling air (waste heat) that has passed through the exhaust hole 36 to the outside of the main body 1. The exhaust is discharged from the external exhaust port 8 of the external exhaust duct 18, and the exhaust discharge direction Exhausts toward the top of the body 1 and to the front side. By directing the exhaust direction toward the upper side and the front side, the wall surface is not soiled by the exhaust even when the rear surface is brought close to the wall surface.

  The machine room 20 is provided in a space portion between the heating chamber bottom face 28a and the bottom plate 21 of the main body 1. On the bottom plate 21, a magnetron 33 for heating food, a waveguide 47 connected to the magnetron 33, A control board 23, other various components described later, a fan device 15 for cooling these various components, and the like are attached.

  The heating chamber bottom surface 28a has a substantially concave central portion, in which the rotating antenna 26 is installed, and the high frequency energy radiated from the magnetron 33 is the waveguide 47 and the output shaft 46a of the rotating antenna driving means 46. Flows into the lower surface of the rotating antenna 26 through the opening 47a, through which it is diffused and radiated into the heating chamber 28. The rotating antenna 26 is connected to the output shaft 46 a of the rotating antenna driving means 46.

  The fan device 15 is connected to a cooling motor attached to the bottom plate 21, and the cooling air 39 generated by the fan device 15 can change the self-heating magnetron 33 in the machine room 20 and the high-frequency output of the magnetron 33. The inverter board 22 on which the inverter power source is mounted, the weight detection means 25 and the like are cooled, and flows between the outside of the heating chamber 28 and the outer frame 7 and between the hot air case 11a and the rear plate 10, and the outer frame 7 The air passes through the exhaust hole 36 while cooling the rear plate 10 and is discharged from the external exhaust port 8 of the external exhaust duct 18.

  A hot air unit 11 is attached to the rear of the heating chamber 28, and a hot air fan 32 that efficiently circulates the air in the heating chamber 28 is attached in the hot air unit 11. A hot air intake hole 31 and a hot air blowing hole 30 are provided.

  The hot air fan 32 rotates by driving a hot air motor 13 attached to the outside of the hot air case 11 a and heats the air circulating in the hot air heater 14.

  On the back side of the top surface of the heating chamber 28, a grill heating means 12 made of a heater is attached. The grill heating means 12 is formed in a flat shape by winding a heater wire around a mica plate, and pressing and fixing the mica plate against the back side of the top surface of the heating chamber 28 to heat the top surface of the heating chamber 28 so that the food in the heating chamber 28 is It is baked by radiant heat.

  The heating chamber bottom surface 28a is provided with a plurality of weight detection means 25, for example, a right weight sensor 25a and a left weight sensor 25b on the front left and right, and a back weight sensor 25c on the rear center, on which the table plate 24 is provided. Is placed.

  The table plate 24 is for placing food, has heat resistance so that it can be used for both heater heating and high-frequency heating, has high-frequency permeability, and has no sanitary problems. It is molded with the material.

  Further, the table plate 24 has upper, middle, and lower multi-stages (3 in the figure) provided on the left and right side surfaces of the heating chamber 28 in order to appropriately bring food close to the grill heating means 12 when heated using the grill heating means 12. Used on a shelf 27).

  Next, the detailed internal structure will be described with reference to FIGS.

  FIG. 4 is a sectional view showing a schematic structure of the weight detection means, and FIG. 5 is an explanatory view for explaining the rotating antenna and the weight detection means on the bottom surface of the heating chamber.

  The weight detection means 25 is attached to the machine room 20 side of the heating chamber bottom surface 28a, and only the plunger 67 faces the heating chamber 28 from the heating chamber bottom surface 28a, and the table plate 24 is placed thereon.

  In this embodiment, the weight detection means 25 uses a capacitance type detection means. The details are composed of a movable electrode 68 and a fixed electrode 69 made of a thin metal material. The fixed electrode 69 and the movable electrode 68 face each other substantially in parallel and hold a predetermined gap, that is, a detection space 70. A capacitor is formed in the detection space 70.

  When the plunger 67 is pushed in accordance with the weight of the food placed on the table plate 24, the movable electrode 68 on the lower surface thereof moves and is determined by the detection space 70 with the stationary electrode 69 that is stationary. The electrostatic capacity is sent to the control means 72 which will be described later, and the control means 72 stores the electrostatic capacity when only the table plate 24 is placed in advance, thereby obtaining the difference in the electrostatic capacity, and the weight of the food. Ask for.

  The weight of the food is obtained by the total of the food weights detected by the respective weight detection means 25, and the position of the food center in the table plate 24 is obtained from the ratio of the detection values of the respective weight detection means 25. .

  When the detection value of each weight detection means 25 is transmitted to the control means 72, the capacitance noise between signal lines connecting the weight detection means 25 and the control means 72 and noise from the surroundings are adversely affected if the capacitance remains unchanged. Since it is easy to receive, each weight detection means 25 is provided with a circuit whose oscillation frequency changes due to a change in capacitance, and the oscillation frequency is sent to the control means 72 as weight data.

  Next, the rotating antenna and its driving will be described.

  As described above with reference to FIG. 2, the microwave radiated from the magnetron 33 passes through the waveguide 47 connected to the magnetron 33, and passes through the opening 47 a of the waveguide 47 to the heating chamber bottom surface 28 a. It flows into the lower surface of the rotating antenna 26 provided in the center, is stirred by the rotating antenna 26 and is radiated into the heating chamber 28.

  The rotating antenna 26 is rotated by the rotating antenna driving means 46 and radiates microwave energy evenly to the food placed in the heating chamber 28. When the rotation stops, the microwave energy received by the food becomes unbalanced and heating unevenness occurs. Therefore, it is possible to intentionally stop the rotating antenna 26 and improve the heating efficiency by utilizing the characteristic of heating imbalance.

  The rotating antenna driving means 46 uses a synchronous motor and is turned on / off by a rotating antenna driving signal 46a from the control means 72, and the number of rotations is determined by the frequency of the applied power source. The antenna driving means 46 used here is provided with a motor and a speed reducer in the driving means. When the frequency of the power supply to be applied is 50 Hz, the time required for one rotation of the output shaft 46a is 12 seconds, and when the frequency is 60 Hz. Is 10 seconds.

  FIG. 6 is a block diagram for explaining the overall operation of the cooking device system.

  In the figure, a power source 76 operates the main body 1 of the heating cooker, and is connected to the control means 72 via the current detection means A75.

  The current detection means A75 detects the current used in the main body 1 of the heating cooker, and is used to detect fluctuations in the power supply 76 and to adjust the heating output to a constant level.

  The range heating unit 77 is an inverter power supply 34 that creates a magnetron 33 and a power supply that can vary the high-frequency output of the magnetron 33. The inverter power supply 34 generates a power supply corresponding to the high frequency output input from the operation unit 6 via the control means 72 and applies it to the magnetron 33. As described above, the generated power supply monitors the power supply 76 with the detection signal from the power supply detection means A75 so that the high-frequency output of the magnetron 33 is not affected by the fluctuation of the power supply 76, and corrects the fluctuation of the power supply 76 with the output. To work.

  The oven heating means 78 is the hot air motor 13 that drives the hot air heater 14 and the hot air fan 32 in the hot air unit 11. The control means 72 adjusts the electric power of the hot air heater 14 so that the temperature in the heating chamber 28 becomes the temperature input from the operation unit 6.

  Reference numeral 12 denotes a heater of the grill heating means 12.

  The rotating antenna driving means 46 is a motor for driving the rotating antenna 26, and a synchronous motor and a gear for reducing the rotational speed are integrated.

  Reference numeral 25 denotes weight detection means.

  Reference numeral 71 denotes an input means, which shows the operation unit 6 and the display unit 5 here.

  Reference numeral 72 denotes a control unit which operates to cook food according to the contents input from the operation unit 6, and detects the state of the food and the state of the heating chamber 28 from each detection unit. And the driving means are operated as necessary.

  The present embodiment has the above configuration, and the operation will be described next.

  First, the door 2 is opened, food (not shown) is placed on the table plate 24 disposed on the bottom surface of the heating chamber 28, and the door 2 is closed.

  After closing the door 2, the high frequency heating is selected by operating the operation unit 6 while viewing the display unit 5 of the operation panel 4 provided on the door 2, and the high frequency output at the time of heating is, for example, 800 W (high frequency output) Can be selected from 5 types of 100 W, 200 W, 500 W, 600 W, and 800 W), and a heating time of 10 minutes is input (a heating time of up to 30 minutes can be set in manual range heating). Next, the start button for starting heating of the operation unit 6 is pressed to start cooking.

  The heating is managed by the control means 72, and a high frequency output value corresponding to the power for cooking the food with the set high frequency output is sent to the inverter circuit 34 which is the range heating means 77. The inverter circuit 34 An output voltage corresponding to the value is applied to the magnetron 33.

  During cooking, the input current is monitored by the current detection means A75, and the output voltage applied to the magnetron 33 is adjusted according to the fluctuation of the input current so that the heating output to the food is always constant.

  When heating is started, the control unit 7 starts subtracting the set heating time from 10 minutes set by the heating timer. At the same time, the elapsed time from the start of heating is started. At this time, the remaining time of the heating timer is displayed on the display unit 5.

  A few seconds after the start of heating, for example, 6 seconds later, the weight detection means 25 detects the weight of the food, and the high frequency output set by the operation unit 6 and the high frequency are set according to the weight of the food detected by the weight detection means 25. The maximum energization allowable time that is the maximum heating time for each high frequency output (here, 600 W, 500 W, 200 W, 100 W that can be set) that is weakened stepwise than the output is calculated.

  The maximum energization allowable time is determined in advance by the maximum energization allowable time (FIG. 7) corresponding to the weight for each high frequency output (five types of settable high frequency outputs 100W, 200W, 500W, 600W, and 800W). Is set.

  FIG. 7 shows the maximum allowable energization time that is the maximum heating time in which the magnetron 33 can operate without difficulty even when heated by the high frequency output that can be set by the operation unit 6 according to the weight of the food, and the food does not ignite or smoke. It is what.

  For example, when heating 200 g of food, the maximum energization allowable time, which is the maximum heating time that can be heated without weakening the high frequency output, is 2 minutes for the maximum energization time that can be continuously heated with the high frequency output of 800 W, 5 minutes for 600 W, It is 12 minutes at 500 W, 20 minutes at 200 W, and 30 minutes at 100 W.

  In addition, when 200g food is set to a high frequency output of 800W and the maximum heating time (30 minutes) is set, the set high time output is gradually reduced so that the set heating time can be heated. After heating for 2 minutes by continuous heating at the initially set high frequency output of 800 W, the high frequency output is weakened to 600 W and heated for 5 minutes (heating time from the start of heating), and then reduced to 500 W for 12 minutes (from the start of heating) It is shown that heating can be reduced to 200 W for 20 minutes (heating time from the start of heating) and then reduced to 100 W for 30 minutes (heating time from the start of heating).

  This is based on the principle that the temperature rise rate of the magnetron is lowered by lowering the high frequency output.

  The high-frequency output and the heating time differ depending on impedance matching determined by the size of the heating chamber 28 of the high-frequency heating device, the dimensions of the waveguide 47, and the like.

  When the weight of the food detected from the weight detection means 25 is 200 g, the maximum allowable energization time that can be heated when the high frequency output is 800 W is 2 minutes from FIG.

  When the calculated maximum energization allowable time is longer than the heating time set by the operation unit 6, the food is heated for the heating time set in the state of the high frequency output set by the operation unit 6.

  However, when the calculated maximum energization allowable time is shorter than the heating time set by the operation unit 6, the high-frequency output is gradually increased from the initially set high-frequency output until the heating time set by the operation unit 6 is reached. Heat with weakening.

  At the initially set high frequency output of 800 W and heating time of 10 minutes, the weight of the food detected by the weight detecting means 25 is 200 g, and the maximum energization allowable time at the high frequency output of 800 W is set to 2 minutes as shown in FIG. Since the time is shorter than 10 minutes, the control means 72 controls the inverter power supply 34 so that the high-frequency output to be heated is weakened from 800 W to 600 W when the elapsed time from the start of heating reaches 2 minutes.

  At this time, according to FIG. 7, the maximum energization allowable time when the weight of the food is 200 g and the high frequency output setting is 600 W is 5 minutes. Since the maximum energization allowable time is shorter than the set time again, the control means 72 controls the inverter power supply 34 so that the high frequency output to be heated is weakened to 500 W when the elapsed time from the start of heating reaches 5 minutes.

  When the high frequency output is weakened to 500 W, the maximum allowable energization time is 12 minutes, the maximum allowable energization time is longer than the set time, and the control unit 7 subtracts 10 minutes of the heating time and the remaining time of the heating timer is 0. Wait until it finishes and heat up.

  If the time set by the customer under the same conditions is 1 minute, the maximum energization allowable time at the time of high frequency output 800 W becomes longer than the set time. Ends.

  In addition, when the heating time set by the customer is 15 minutes, the high-frequency output that can be heated longer than the set time for the maximum energization time when the weight of the food is 200 g is gradually reduced from the high-frequency output set up to 200 W. Then, heating is performed for the maximum energization allowable time with each weakened high-frequency output, and the heating is finished after waiting for the heating timer of the set heating time to become zero.

  In addition, when the door 11 is opened in the middle of heating, the control part 7 stops heating temporarily. When the door is closed from this state and the start button is pressed, heating is restarted, and the heating timer resumes subtraction from the remaining time at the time of pause. At this time, there is a possibility that the food in the heating chamber 28 has been replaced. Therefore, if the high frequency output has decreased from 800 W to 600 W or less before the temporary stop, it is returned to the set high frequency output 800 W and the elapsed time is restarted. Reset time from the start and start timing. However, it is possible to maintain the high-frequency output immediately before the suspension even when restarting with an emphasis on safety, and the elapsed time can be restarted from the elapsed time before the suspension.

  As described above, according to the present embodiment, even if the customer sets a time that is significantly longer than the heating time suitable for the weight of the food, the heating ends at the heating time set by the customer. In that case, the temperature of the magnetron is prevented from rising, and the food is prevented from smoking and igniting, ensuring the safety of the cooker body and providing customers with a sense of security. Can give

6 Operation part 25 Weight detection means 33 Magnetron 72 Control means

Claims (2)

A heating chamber for heating the food;
A table plate placed on the bottom of the heating chamber;
Weight detection means for supporting the table plate and detecting the weight of food placed on the table plate;
A magnetron for heating the food with high frequency output;
An inverter power supply capable of changing the high-frequency output of the magnetron;
In a high-frequency heating apparatus comprising a high-frequency output for heating the food and an operation unit for setting a heating time,
When the maximum energization allowable time for each high frequency output according to the weight of the food detected by the weight detection means is calculated, and the heating time of the food set in the operation unit is longer than the maximum energization allowable time, A high-frequency heating apparatus comprising control means for heating the food by reducing the high-frequency output after the maximum energization allowable time has elapsed.   When the heating time of the food set in the operation unit is longer than the maximum allowable energization time, the control means heats the food by gradually reducing the high frequency output after the maximum allowable energization time has elapsed. The high-frequency heating device according to claim 1.

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