JP3817382B2 - Microwave heating device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetron application apparatus that is a high-frequency application device, and more particularly to a heating apparatus using a magnetron.
[0002]
[Prior art]
Generally, there is a heating device such as a microwave oven as a magnetron application device.
[0003]
Heating an object using microwaves (high frequency) generated by a magnetron has good heating efficiency. Therefore, the microwave heating apparatus using a magnetron is used not only for a microwave oven for home use but also for industrial use.
[0004]
FIG. 11 shows a conceptual diagram when the magnetron is used in a microwave oven. In the figure, 1 is a heating case (oven) for a microwave oven, 302 is a door, 3 is an object to be heated, 5 is a magnetron, 5a is a magnetron antenna, 8 is a power source for operating the magnetron, and 307 is a fan. 308 is a cooling air generated by a fan, 6 is a waveguide for guiding high-frequency power generated by the magnetron into the heating housing, and 4 is a stirrer for diffusing the supplied high-frequency power.
[0005]
The article 3 to be heated is set in the heating casing 1 from the door 302.
[0006]
Microwaves generated by the magnetron 5 are radiated from the antenna 5 a and supplied through the waveguide 6 into the heating housing 1 where the object to be heated 3 is located. At this time, since the magnetron 5 generates heat, the cooling air 308 is sent to the magnetron 5 by the fan 307. The microwave power supplied into the heating housing 1 is diffused by the stirrer 4 so that the article 3 to be heated is uniformly heated.
[0007]
In addition, general heat treatment includes a heat treatment method in which an object to be heated is immersed in hot water, a heat treatment method in which hot water is sprayed from a spray nozzle into a heating casing, and a high-temperature steam is heated in the heating casing containing the object to be heated. There is a heat treatment method filled with
[0008]
Furthermore, Japanese Utility Model Publication Nos. 60-8710 and 60-21975 disclose heat sterilization apparatuses that irradiate microwaves in a heating chamber controlled to a high pressure. Further, a stirrer that is a means for uniformly heating is disclosed.
[0009]
However, since the temperature of the object to be heated cannot be detected, the heat sterilization apparatus of the above publication is heated in a state without airtight packaging, and the relationship between temperature and time is examined in advance, and the pressure data is determined using the temperature data. A method of determining the pressurizing condition by measuring the temperature of the sealed container (Jokosho 60-21975) or the like is adopted.
[0010]
In such a microwave heating apparatus, it cannot be said that the pressure is sufficiently accurate with respect to the pressurizing condition corresponding to the actual food temperature. There are many fluctuation factors such as individual differences in food, microwave heating output differences, temporal fluctuations, food position fluctuations, etc., which causes pressure differences inside and outside the sealed container, and the container is damaged due to deformation・ It may cause damage.
[0011]
Japanese Patent Publication Nos. 51-12133, 53-119183, 60-8710, and 60-21975 simply heat a packaged object to be heated by an internal heating method. This is to prevent the container from bursting, and it is not considered to raise the heating temperature simultaneously with pressurization. Further, no consideration is given to the stress applied to the means for heating uniformly, that is, the increase in friction due to pressurization.
[0012]
[Problems to be solved by the invention]
Conventional microwave heating devices such as microwave ovens have the following problems.
[0013]
The temperature of the object to be heated in the heating casing rises when irradiated with microwaves. Thereafter, when the temperature reaches 100 ° C., the moisture of the object to be heated starts to evaporate. The object to be heated loses the irradiated energy due to the latent heat due to the evaporation of moisture, so the temperature does not easily rise above 100 ° C.
[0014]
There is no need to raise the temperature to 100 ° C. or higher if the object to be heated is simply heated for edible purposes, but a temperature of 100 ° C. or higher may be required when heating the object to be sterilized. is there.
[0015]
For example, sterilization of retort pouch-stuffed foods and fish sausages requires high-temperature sterilization treatment at 100 to 140 ° C. to sterilize heat-resistant bacteria.
[0016]
If a conventional microwave heating apparatus is used for high-temperature sterilization, the temperature of the object to be heated cannot be raised sufficiently.
[0017]
In addition, when large microwave power is injected into the heating casing and the temperature of the object to be heated is forcibly raised, there is a problem in that moisture escapes from the object to be heated.
[0018]
In addition, there is a problem that a mechanical load due to pressurization is applied to a means for uniformizing microwave heating such as a stirrer or a turntable by pressurization, resulting in unstable operation.
[0019]
The present invention improves this defect and rapidly sterilizes an object to be heated at high reliability.
[0020]
Furthermore, heat treatment methods such as a heat treatment method in which the object to be heated is immersed in hot water, a heat treatment method in which hot water is sprayed from the spray nozzle into the heating housing, and a heat treatment method in which the heating housing containing the object to be heated is filled with high-temperature steam. There is a way. In such a heat treatment method, since heat is transferred from the surface of the object to be heated, a temperature difference occurs between the surface and the inside. There is also a problem that it takes time to heat. Since the surface portion of the object to be heated is exposed to a high temperature for a long time, the object to be heated may be altered.
[0021]
The present invention solves such problems, and an object of the present invention is to provide a magnetron application apparatus capable of performing heat treatment in a short time with a small amount of energy by a simple configuration means.
[0022]
Another object of the present invention is to provide a magnetron application apparatus that performs high-temperature sterilization of an object to be heated quickly with high reliability.
[0023]
[Means for Solving the Problems]
In order to achieve the above object, a microwave heating apparatus according to the present invention includes a heating housing portion that accommodates an object to be heated, and a microwave power for supplying microwave power to the heating housing. It has a supply part and a pressurization system part for making the inside of the case for heating into a high pressure.
[0024]
Further, the heating housing in which an object to be heated is sealed has a sealed structure, and microwave heating is performed while applying a pressure higher than atmospheric pressure by a pressurizing device. In addition, the heating case has a uniformizing means for uniformly performing microwave heating, and the driving portion for driving the same is made a sealed structure different from the heating case, so that the pressure is higher than the pressure in the heating case. Pressurize to a higher level.
[0025]
The heating housing that puts the object to be heated has a sealed structure, and it is configured to perform microwave heating while applying a pressure higher than atmospheric pressure by a pressure device, and a sensor that detects deformation of the package of the object to be heated When the atmosphere of the object to be heated is provided and pressurized, the deformation of the object to be heated by microwave heating, particularly the packaging part, is monitored, and the pressing pressure is controlled so that the packaging part does not deform more than necessary.
[0026]
According to the above means, since the microwave heating is performed by increasing the pressure in the heating casing, the object to be heated is heated to a temperature higher than 100 ° C. using the microwave in a state in which the evaporation of the moisture of the object to be heated is suppressed. Can be heat treated.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
In an embodiment of the present invention, a heating casing portion that houses an object to be heated, a microwave power supply section for supplying microwave power to the heating casing, and a heating casing It is a microwave heating device having a pressurization system part for making the inside high pressure.
[0028]
Furthermore, the microwave heating apparatus has the following configurations in addition to the above configuration.
[0029]
(1) When performing microwave heating on the object to be heated, the pressure of the atmosphere around the object to be heated is set higher than atmospheric pressure during microwave heating.
[0030]
(2) Dispersion means for dispersing the microwaves applied to the inside of the heating housing is provided, and the drive unit of the dispersion means is arranged in the pressurizing chamber, and the pressurization in which the part for driving the dispersion means is arranged Increase the chamber pressure above atmospheric pressure.
[0031]
(3) It has a rotating means for rotating an object to be heated arranged inside the heating casing, and a driving part of the rotating means is arranged in the pressurizing chamber, and a part for driving the rotating means is arranged. The pressure in the pressurizing chamber is increased from atmospheric pressure.
[0032]
(4) A means for changing the time or intensity of microwave irradiation is provided.
[0033]
(5) A stage in which a pressure sensor and a temperature or humidity sensor are provided in a part of the heating housing, and the object to be heated is microwave-heated at a pressure higher than the atmospheric pressure, and the humidity in the heating housing rapidly increases. Means for controlling to end the microwave heating.
[0034]
(6) A position sensor and a shape sensor are arranged in a part of the heating casing, and microwave heating is performed while monitoring the position and shape of the object to be heated.
[0035]
(7) A plurality of heating casings are prepared as microwave means, and the object to be heated is sequentially heated.
[0036]
(8) Prior to microwave heating or simultaneously with microwave heating, a means for heating the periphery of an object to be heated with high-temperature steam or an electric heater is provided.
[0037]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0038]
FIG. 1 is a cross-sectional view showing an embodiment of a microwave heating apparatus according to the present invention.
[0039]
In FIG. 1, 1 is a heating housing, 1a is an upper housing, 1b is a lower housing, 1c is a joint between the upper housing 1a and the lower housing 1b, 2 is a tray, 3 is an object to be heated, 4 is A stirrer for diffusing the supplied high-frequency power, 5 is a magnetron, 5a is a magnetron antenna, 6 is a waveguide that guides the high-frequency power generated by the magnetron into the heating housing, 7 is a gas discharge unit, and 8 is a magnetron. , 9 is a dielectric, 10 is a pressurized system section, 10a is a pressurized gas supply pipe, 10b is a hole, 13 is a temperature sensor, 14 is a pressure sensor, 15 is a position sensor, 16 is It is chalk.
[0040]
Microwaves generated by the magnetron 5 are emitted from the antenna 5 a and supplied through the waveguide 6 into the heating housing 1 where the object to be heated 3 is located. At this time, since the magnetron 5 generates heat, the cooling air is sent to the magnetron 5 by the fan. The microwave power supplied into the heating housing 1 is diffused by the stirrer 4 so that the article 3 to be heated is uniformly heated.
[0041]
The heating housing 1 is composed of an upper housing 1a and a lower housing 1b whose inner sides are metal, and when these are vertically joined, the joint 1c has a structure in which leakage of microwaves remains within the regulation. Wave leakage is prevented. Further, the microwave heating apparatus of FIG. 1 has a structure in which confidentiality is improved in order to make the inside high pressure.
[0042]
A stirrer 4 formed of a metal plate for reflecting radio waves is a first uniformizing means for uniformly heating an object to be heated, and is a driving device supported by a rod 4a made of metal or plastic. The motor 4b is configured to rotate.
[0043]
The tray 2 made of glass or ceramic is a support for supporting the object to be heated 3, and is a second uniformizing means for uniformly heating the object to be heated 3. Further, the tray 2 supports an object to be heated at an appropriate position of the heating housing 1 by a support rod 2a made of ceramic or metal. Further, the support bar 2a is connected to a motor 2b which is a driving device, and transmits the rotation of the motor 2b to the tray 2. In this embodiment, the tray 2 is rotated, but it may be moved up and down or left and right. The purpose of heating while moving the object to be heated 3 is to heat the object to be heated 3 without unevenness, and it is not necessary to move the object to be heated 3 if it can be heated without unevenness.
[0044]
The electron tube magnetron 5 that generates microwave power radiates microwave power from the antenna 5 a, and the microwave power is irradiated to the inside of the heating housing 1 through the waveguide 6 connected to the heating housing 1. Is done.
[0045]
The dielectric 9 made of ceramic, Teflon, or the like is a wall for isolating the waveguide in which the antenna 5 a is disposed from the internal space of the heating housing 1. The dielectric 9 is configured to shield the antenna 5a of the magnetron 5 from the steam inside the heating housing 1 and prevent deformation, breakage due to corrosion, dirt, and pressure. The dielectric 9 is fixed to the heating casing by silver brazing or the like, or is in close contact with the heating casing 1 through an O-ring such as rubber.
[0046]
In order to operate the magnetron 5, a high voltage power source or a low voltage power source for cathode heating is required. The power supply unit 8 is connected to the magnetron by a high voltage cable 8a. In addition, the anode part of the magnetron becomes high temperature and is cooled forcibly to cool it. In FIG. 1, the cooling method is omitted.
[0047]
The heating housing 1 is structured in consideration of improving confidentiality.
[0048]
A pressurizing system unit 10 for sending a gas such as air to the outside of the heating housing to increase the pressure inside the heating housing is provided. The pressurized gas is introduced into the casing through a hole 10b provided in the heating casing 1 by a pressurized gas supply pipe 10a. Although the hole 10b is provided in the lower housing 1b in FIG. 1, it may be provided in the upper housing 1a. The hole 10b is a hole having a diameter that does not allow microwaves emitted from the magnetron to pass therethrough. Further, a plurality of holes 10b may be provided in accordance with the capacity of the heating casing 1, and by configuring in this way, a large amount of gas can be heated without leaking microwaves from the heating casing 1. It can be sent into the housing 1.
[0049]
The gas discharge unit 7 is a hole for discharging the gas used to increase the pressure in the heating housing 1 and is connected to a gas discharge control device. Moreover, the gas discharge part 7 is a hole with a diameter which does not allow the microwave radiated from the magnetron to pass therethrough. Further, a plurality of gas discharge portions 7 may be provided. By configuring in this way, a large amount of gas can be discharged from the heating housing 1 without leaking microwaves from the heating housing 1. it can.
[0050]
In the microwave heating apparatus illustrated in FIG. 1, the upper casing 1 a and the lower casing 1 b are separated, the heated object 3 is disposed on the tray 2, and the upper casing 1 a and the lower casing 1 b are brought into close contact with each other. Then, the pressurizing system unit 10 is operated to send a gas body such as high-pressure air or high-pressure nitrogen to the inside of the heating casing, and the pressure inside the heating casing rises.
[0051]
On the other hand, the microwave power is sent from the magnetron 5 to the inside of the heating casing through the waveguide 6 and irradiated to the article 3 to be heated, so that microwave heating is performed. A quarter wavelength choke 16 is provided at the joint 1c of the upper casing 1a and the lower casing 1b so that the microwave does not leak. The choke 16 is installed in a direction perpendicular to the traveling direction of the leakage microwave to the outside, that is, the thickness direction of the side wall forming the heating housing.
[0052]
The width in the direction perpendicular to the thickness direction of the side wall forming the heating casing of the choke 16 shown in FIG. 1, that is, the height of the choke 16 in FIG. 1 is a quarter of the microwave emitted from the magnetron. Is the wavelength. The choke 16 is formed in the upper casing 1a over the entire circumference to prevent microwave leakage.
[0053]
Although the choke 16 is provided in the upper housing 1a in FIG. 1, it may be provided in the lower housing 1b. In FIG. 1, the heating casing is divided into upper and lower parts. However, when the heating casing is divided into left and right parts, the horizontal width of the choke may be set to a quarter wavelength of the microwave. Further, a gasket may be used instead of the chalk 16.
[0054]
The pressure sensor 14 monitors the pressure of the atmosphere of the object to be heated, and the temperature sensor 13 is composed of a radiation thermometer or the like, and is attached to the heating casing 1 to detect the temperature of the object to be heated or the temperature in the heating casing. The temperature sensor 13 may be a humidity sensor, and may include both a temperature sensor and a humidity sensor as necessary.
[0055]
A plurality of sensors such as a temperature sensor, a humidity sensor 13, a pressure sensor 14, and a position sensor 15 are installed in the heating casing 1, and based on the measured data, the pressure in the heating casing 1 is adjusted and microwaves are used. The power can be adjusted. The position sensor 15 detects the distance from the sensor to the package of the object to be heated and controls the pressure condition and the microwave output.
[0056]
According to the present embodiment, since the object to be heated 3 is heated at a high pressure, the internal moisture does not evaporate even when the temperature exceeds 100 ° C., and the object 3 can be heated to a temperature required for sterilization.
[0057]
For example, the boiling point of water is 100 at 2 atm (atm), 121 at 2 atm, 134 at 3 atm, 134 at 4 atm, 144 at 4 atm, 152 at 5 atm, and 160 at 6 atm.
[0058]
By controlling the pressure in the heating casing, heating to the boiling point of water at each atmospheric pressure is possible.
[0059]
In particular, in order to sterilize the object to be heated, the temperature must be 120 ° C. or higher, and it is necessary to apply pressure exceeding 2 atm.
[0060]
For example, since Clostridium botulinum requires heat treatment at 105 ° C. or higher, heat treatment can be performed by setting the inside of the heating housing to 2 atm.
[0061]
Further, for example, spore bacteria need to be heat-treated at 120 ° C. or higher, so that heat treatment is possible at 2 atmospheres. However, since the boiling point of water is 121 ° C. at 2 atmospheres, the moisture of the object to be heated evaporates with a control error of 1 ° C. Therefore, it is preferable to set the pressure inside the heating housing to a pressure exceeding 2 atm.
[0062]
In the case of the heat treatment for sterilization, more preferably, the pressure in the heating housing is set to 4 atm so that heating at 140 ° C. can be performed by microwave heating, and the sterilization can be surely performed. In this case, since the time can be shortened, the quality of the object to be heated can be further reduced.
[0063]
Further, when heating an object to be heated that is sealed and packaged, the pressure in the heating casing is higher than that in the sealed package even during heating. That is, the atmospheric pressure in the heating housing is always higher than the atmospheric pressure in the sealed package. By doing in this way, it can heat at high temperature, without bursting the thing of a sealed state.
[0064]
Since microwaves are used, the object to be heated is directly dielectrically heated, so that it is extremely efficient and generates heat from the inside, so that a quick sterilization process can be performed. It is particularly suitable for heat treatment of foods because it does not deteriorate or lose moisture and does not deteriorate the quality of the object to be heated.
[0065]
The microwave power is applied to the object to be heated after increasing the pressure in the heating housing 1. With such a structure, rapid heating is possible, and the object to be heated can be heated to a high temperature in a short time.
[0066]
Moreover, you may irradiate a to-be-heated object simultaneously, raising the pressure in the housing | casing 1 for a heating with microwave electric power. In such a configuration, the pressure of the atmosphere of the object to be heated increases as the temperature of the object to be heated increases. Therefore, the object to be heated does not deform due to the pressure generated by pressurizing the inside of the heating casing. Such a method is effective for a sealed object to be heated, and can prevent deformation and breakage of the object to be heated.
[0067]
Next, the operation part of the magnetron will be described with reference to FIG.
[0068]
FIG. 2 shows a cross-sectional structure of the magnetron. A plurality of anode vanes 102 are radially formed around the cathode filament 101. The plurality of anode vanes 102 are fixed to the anode cylinder 103 by brazing or the like, or the anode vanes 102 are integrally formed with the anode cylinder 103 by extrusion molding or the like.
[0069]
Cylindrical permanent magnets 104 are installed above and below the anode cylinder. The magnetic flux from the magnet 104 passes through the magnetic pole 105 and generates a necessary DC magnetic field in the vertical direction with respect to the working space formed between the cathode filament and the anode vane. The yoke 106 passes the magnetic flux of the permanent magnet.
[0070]
Electrons emitted from the cathode filament form a high-frequency potential on each anode vane while circularly moving under the influence of a DC magnetic field.
[0071]
The anode vanes 102 are provided in the center direction from the inner wall of the cylinder 103, and are arranged radially when viewed from an axis passing through the center.
[0072]
This anode vane 102 is connected to every other one by a first strap ring made of two annular bodies having different diameters and a second strap ring.
[0073]
One of the anode vanes 102 in FIG. 2 is provided with an antenna lead 107 for guiding microwaves by silver brazing or the like.
[0074]
An antenna lead 107 implanted in the vane 102 is inserted through the magnetic pole 105 enclosed in one opening side of the anode cylinder 103 and passes through almost the center of the sealing metal 141. A cylindrical insulator 111 is hermetically sealed at the end of the sealing metal 141, and a cup-shaped exhaust pipe support brazed to the outer periphery of the exhaust pipe 109 at one end of the cylindrical insulator 111. 112 is brazed.
[0075]
After exhausting the inside of the magnetron tube, the exhaust pipe 108 is sealed off together with the antenna lead 107, and the antenna cover 110 is press-fitted and fixed to the exhaust pipe support 112 to protect its tip. Here, the recess formed by sealing off the exhaust pipe 108 and the antenna lead 107 is a choke portion 109 for preventing unwanted radiation.
[0076]
The magnetron shown in FIG. 2 has a shape in which both the exhaust pipe 108 and the antenna lead are sealed, but a magnetron using a dome-shaped ceramic for the microwave oscillation portion may be used.
[0077]
The cathode filament 101 for generating electrons is generally made of thorium oxide (ThO). ₂ ) Is used. In order to improve the electron emission characteristics, a carbonized layer (W ₂ C) is formed. The cathode filament 101 is engaged with and supported by a high melting point brazing material such as a ruthenium-molybdenum eutectic alloy with the upper end shield 121 and the lower end shield 122.
[0078]
Upper end shield 121 and lower end shield 122 are supported by cathode leads 123 and 124, respectively. These end shields and cathode leads generally use Mo from the viewpoint of heat resistance and workability.
[0079]
The two cathode leads are supported by the input side ceramic 125. The cathode leads 123 and 124, together with the cathode terminal 126, are brazed with silver so as to keep vacuum-tightness on the input side ceramic.
[0080]
When vibration, impact, etc. are applied to the magnetron, the cathode leads 123 and 124 vibrate, and the manner of vibration differs between the cathode leads 123, 124. Therefore, mechanical stress is generated in the cathode filament 101, and the cathode filament 1 May cause disconnection. In order to prevent this, a spacer 127 is used. Due to the effect of the spacer, even when the cathode lead vibrates, the movements of the cathode leads 123 and 124 due to the vibration are almost the same, so that the stress applied to the cathode filament can be reduced. The sleeve 128 is for supporting the spacer 127 at a predetermined position.
[0081]
The cathode terminal 126 is connected to a choke coil 131. The choke coil 131 is connected to a feedthrough capacitor 132 to which a case 133 of the input unit is attached, and the feedthrough capacitor is connected to a power source. The cathode terminal 126 and the choke coil 131 are generally connected by welding, and the choke coil 131 and the feedthrough capacitor 132 are also generally connected by welding. Here, the choke coil 131 and the feedthrough capacitor 132 form a low-pass filter when the power supply side is viewed from the inside of the magnetron. This is to prevent the microwave generated in the working space between the cathode filament and the anode from being radiated to the outside through the cathode filament and the cathode lead.
[0082]
Each cathode lead is connected in series with the choke coil, and the other end of the choke coil is opposed to the ground via a capacitor.
[0083]
The case 133 of the input unit is sealed by the lid 134 and prevents microwaves from being radiated to the outside.
[0084]
The input side ceramic 125 is engaged with the anode cylinder 103 via the seal part 142 while maintaining a vacuum airtightness, and the output side ceramic 111 is engaged with the anode cylinder 103 via the seal part 104 while maintaining a vacuum airtightness. Match.
[0085]
The yoke 144 is electrically connected to the seal component 141 via the metal gasket 143, and the seal component 141 is at the same potential as the anode cylinder. Therefore, the yoke 144 is at the same potential as the anode cylinder. Yes.
[0086]
The yoke 144 and the yoke 106 are generally connected by caulking.
[0087]
The anode of the magnetron becomes high temperature due to heat radiation from the cathode filament 101, heat generation due to electrons colliding with the anode vane 102, and the like. When the anode becomes hot, it causes adverse effects such as changing the magnetic characteristics of the magnet and adversely affecting the peripheral devices of the magnetron. The cooling fin 145 is provided in order to counter this problem. In general, when the magnetron is operated, cooling air is sent to the cooling fins by a fan installed in a microwave oven or the like. Although the air-cooling embodiment is described in FIG. 2, it may be a liquid-cooling type in which a tube through which the liquid passes is brought into contact with the anode cylinder instead of the cooling fin 145 and the liquid is circulated and cooled.
[0088]
FIG. 3 shows an example of a drive circuit for driving the magnetron.
[0089]
In the figure, reference numeral 231 denotes a magnetron. The direct current power source that supplies direct current power to the switching power source device includes a commercial alternating current power source 203 and a full-wave rectifier.
[0090]
A filter composed of a reactor and a capacitor is connected to the DC output terminal of the rectifier, but this filter does not smooth the rectified current, but high-frequency noise contained in the oscillation current leaks through the AC power supply side. This is to prevent the occurrence of disturbing waves.
[0091]
The switching device includes a transistor 211 and repeats an on-off operation by an on signal generation circuit and a drive circuit. The switching device includes a damper diode 215 connected in antiparallel to the transistor 211 and a resonance capacitor 213 connected in parallel.
[0092]
The power supply device has a step-up transformer having a primary winding 219 and three secondary windings 221, 223, and 225. The primary winding 219 is connected to a filter via a switching device, and a series resonance circuit is configured by the capacitor 213 and the primary winding 219.
[0093]
The secondary winding 221 is connected to the magnetron 231 through a voltage doubler rectifier composed of a capacitor and a high voltage diode. The current detector 233 is used to detect a load current flowing through the magnetron 231.
[0094]
The secondary winding 225 is provided for heating the cathode of the magnetron 231, and the other secondary winding 223 is for generating a voltage for feedback of the output. Further, the secondary winding 224 is rectified and used as a power source for a control circuit or the like.
[0095]
FIG. 4 is a sectional view showing another embodiment of the present invention. The same parts as those in FIG.
[0096]
A cover 11 made of metal or plastic is disposed outside the support bar 2a for supporting and rotating the tray 2 and the motor 2b. The inside of the cover 11 forms a lower pressurizing chamber, and the lower pressurizing chamber can endure even when a pressure equivalent to the inside of the heating housing 1 is applied.
[0097]
Further, a cover 12 made of metal or plastic is disposed outside the rod body 4a for supporting and rotating the stirrer 4 and the motor 4b. The inside of the cover 12 forms an upper pressurizing chamber, and the upper pressurizing chamber is heated. It can endure even when a pressure equivalent to the inside of the housing 1 is applied.
[0098]
4 shows that the heating housing 1 is provided with a temperature sensor 13 for detecting the temperature of the object 3 to be heated and a pressure sensor 14 for detecting the atmospheric pressure of the object 3 to be heated. A gas discharge unit 7 connected to a gas discharge control device for controlling discharge of the pressurized gas body inside the body 1 is provided.
[0099]
The pressurized gas from the pressurizing system unit 10 is once guided to the housing 10c. Thereafter, the gas is guided to the lower casing 1b, the upper pressurizing chamber, and the lower pressurizing chamber by the three pressurized gas supply pipes 10a connected to the casing 10c. The inside of the heating housing 1 is pressurized with this pressurized gas, and at the same time, the upper pressurizing chamber and the lower pressurizing chamber are pressurized.
[0100]
The heating casing 1 into which the article 3 to be heated is placed has a hermetically sealed structure, and microwave heating is performed while applying a pressure higher than atmospheric pressure to the casing 1 with a pressure device. In addition, the heating case has a uniformizing means for uniformly performing microwave heating, and the driving portion for driving the heating unit is a pressure chamber portion having a sealed structure different from the heating case, By pressurizing to a state that is somewhat higher than the pressure in the casing, the atmospheric pressure in the heating casing is prevented from lowering.
[0101]
In order to make the pressure in the pressurizing chamber with the driving device higher than the pressure in the heating casing, heating may be performed while the gas in the heating casing is being removed from the gas discharge section 7.
[0102]
By operating while discharging an appropriate amount of gas in the heating housing, the pressure in the heating housing can be made slightly lower than the pressure in the pressurizing chamber.
[0103]
Since an appropriate amount of the pressurized gas body inside the heating housing 1 is discharged from the gas discharge unit 7, the pressure inside the heating housing 1 is higher than the pressure inside the upper and lower pressure chambers 11, 12. Slightly decreases. For this reason, the water vapor generated from the object to be heated is discharged from the gas discharge unit 7, and the water vapor content of the microwave heating uniformizing means such as a motor in the vertical pressurizing chamber is maintained because the pressure is kept higher in the vertical pressurizing chamber. It does not enter the drive unit. As a result, the deterioration of the electrical insulation of the motor and the occurrence of corrosion are suppressed, and the operational reliability can be improved and the operation can be performed for a longer period.
[0104]
The hole that connects the pressurizing system 10 and the heating casing 1, the upper pressurizing chamber, and the lower pressurizing chamber is a hole having a diameter that does not allow microwaves emitted from the magnetron to pass therethrough. Further, a plurality of holes may be provided, and by configuring in this way, a large amount of gas can be introduced into the heating casing 1, the upper pressurizing chamber, and the lower part without leaking microwaves from the heating casing 1. It can be sent into the pressure chamber.
[0105]
For this reason, a gas body does not leak from the support rod 2a penetrating the heating housing 1 or the penetrating portion of the rod body 4a, the pressure in the heating housing can be kept constant, and the pressure in the heating housing can be maintained. Can be prevented.
[0106]
In the microwave heating apparatus of FIG. 4, it is not necessary to take special measures against airtightness on the support rod 2 a penetrating portion of the heating housing 1. Further, there is no need to devise the structural surface so that the loss of the gas body from the through portion is reduced.
[0107]
Further, the torque for rotation increases due to the pressurization in the heating housing 1. According to the microwave heating apparatus of FIG. 4, the burden on the motor or the rotating unit can be reduced.
[0108]
This phenomenon is the same for the 4 stirrer. According to the microwave heating apparatus of FIG. 4, the problem of the rotating part of the stirrer by the rod 4a and the motor 4b can be reduced by increasing the friction due to pressurization and moving the position. . That is, the occurrence of a problem that the friction is increased by the pressure and the life is shortened is extremely reduced.
[0109]
FIG. 5 is a sectional view showing still another embodiment of the present invention. The same parts as those in FIG.
[0110]
In FIG. 5, 10d is a through-hole which penetrates an upper pressurization chamber, a lower pressurization chamber, and a heating housing. The through hole 10d is formed so that pressurized gas can escape from the heating casing 1 to the upper pressurizing chamber and the lower pressurizing chamber. For this reason, the pressurized gas supply pipe can be simplified.
[0111]
The through hole penetrating the upper pressurizing chamber, the lower pressurizing chamber, and the heating casing is a hole having a diameter that does not allow microwaves emitted from the magnetron to pass therethrough. Further, a plurality of through holes may be provided. By configuring in this way, a large amount of gas is fed into the heating casing 1 through the hole 10b without leaking the microwave from the heating casing 1. Can do.
[0112]
In the microwave heating apparatus of FIG. 5, the support rod 2 a penetrating the heating housing 1 is disposed in the same atmospheric pressure as the heating housing 1. Therefore, it is not necessary to take special measures against airtightness in the through portion of the support rod 2a of the heating housing 1. Further, there is no need to devise the structural surface so that the loss of the gas body from the through portion is reduced.
[0113]
In the heating device of the present invention, whether or not sufficient heating is necessary is a state in which the gas pressure inside the heating housing is a pressure for reaching the temperature necessary for sterilization and exceeds the boiling point of moisture. Whether the temperature is a value necessary for sterilization. In order to ensure this condition, a pressure sensor and a temperature sensor are attached to the wall portion of the heating casing 1 in the microwave heating apparatus of FIGS. 1, 4, and 5.
[0114]
The pressurization system unit 10 is controlled by the output of the pressure sensor, and the magnetron 5 and its power supply unit 8 are subjected to operation control considering both the output of the temperature sensor and the output of the pressure sensor. That is, it is controlled so that a predetermined temperature is obtained over a certain time at a certain set pressure.
[0115]
Also, as a method of ending heating when a certain temperature is reached, a humidity sensor is provided on the wall of the heating housing 1 and the inside of the heating housing 1 has a set pressure value, and the output of the humidity sensor increases rapidly. In such a case, it is effective to determine that the set temperature has been reached and stop the microwave heating. In addition, although the apparatus of this invention is the microwave heating in pressurized gas, although not shown in figure, measures, such as a safety valve, are taken for safety.
[0116]
FIG. 6 shows still another embodiment of the present invention, and the same parts as those in FIG. In order to heat efficiently with microwaves, it becomes a microwave heat sterilizer with energy-saving features, but when foods sealed and packaged such as retort foods are targeted, food temperature can not be measured directly, It is generally difficult to apply pressure corresponding to the temperature.
[0117]
However, according to the present invention, the container tends to deform when there is a pressure difference between the inside and outside of the sealed and packed food such as retort food, but the position sensor 15 monitors the position of the container. Alternatively, the microwave output is controlled to keep the deformation within a certain range.
[0118]
For this reason, since control suitable for the temperature of the internal food is always performed, damage and rupture of the package can be prevented, and microwave heating to a temperature sufficient for sterilization can be performed.
[0119]
For example, as shown in FIG. 9, when the difference between the internal pressure and the external pressure of the article 3 to be heated occurs, the upper cover 3a of the package is deformed into a convex or concave shape as indicated by a dotted line, but the position sensor 15 detects the position of the upper cover 3a. Then, control is performed by the output.
[0120]
Even if the food temperature in the package is unknown, the food pressure can be substantially known from the value of the pressure sensor 14 because the internal pressure changes corresponding to the food temperature.
[0121]
Further, the position sensor 15 can use an image sensor to detect and control the change in the entire outer shape even when the object to be heated 3 is in a thin plastic bag. Such a position sensor 15 is suitable for heating foods that are more easily deformed.
[0122]
Since the position sensor 15 detects the deformation state of the container and controls the atmospheric pressure and the microwave output, it is possible to suppress the deformation of the container and prevent the container from being damaged or ruptured.
[0123]
FIG. 7 is a cross-sectional view of a main part for explaining a structure for preventing leakage of microwaves in the through portion of the bar 4a supporting the support bar 2a or the stirrer 4 of the tray 2.
[0124]
When the support bar 2a or the bar 4a is made of metal, microwaves may leak from that portion.
[0125]
A protruding portion 17 is provided in the through-hole of the support rod 2a or the rod body 4a of the heating housing 1.
[0126]
According to the configuration of FIG. 7, when the support bar 2a or the bar 4a is a metal, a capacitor is formed by the support bar 2a or the bar 4a and the convex portion 17, and the microwave leaks into the space where the motor 2b or the motor 4b is located. Can be prevented.
[0127]
Further, when the support bar 2a or the bar 4a is made of metal, the through holes and the inner diameters of the protrusions and the dimensions for attenuating the radio wave transport are set, and if the dimension H is sufficiently large, leakage of radio waves from this space can be prevented. be able to.
[0128]
FIG. 8 is a cross-sectional view of a main part of another configuration for explaining a structure for preventing leakage of microwaves in a through portion of the support body 2a of the tray 2 or the bar body 4a that supports the stirrer 4. The same parts as those in FIG.
[0129]
A choke 18 is provided in the through-hole of the support rod 2a or the rod body 4a of the heating casing 1. The horizontal width of the choke 18 is a quarter wavelength of the microwave.
[0130]
According to the configuration of FIG. 8, the choke 18 can prevent microwaves from leaking into the space where the motor 2b or the motor 4b is located.
[0131]
FIG. 9 is a view showing still another embodiment of the present invention. The same parts as those in FIG. 6 are given the same numbers.
[0132]
In order to perform uniform heating in microwave heating, the shape of the stirrer 4 is different from that in FIG. 6 and the temperature pattern of microwave heating in the heating housing 1 is changed. The microwave heating apparatus of FIG. 9 has a temperature pattern that becomes high in the vicinity. That is, the temperature of the object to be heated in the portion normally located on the central axis of the turntable is increased, but in FIG. 9, the temperature is increased outside the central axis. Specifically, the stirrer has a square shape. Of course, the position of the stirrer 4, the position of the turntable, and the radiation position of the magnetron may be changed.
[0133]
Using the two types of microwave heating apparatus, the microwave heating apparatus in FIG. 9 for heating the periphery of the object to be heated and the microwave heating apparatus for heating the center of the object to be heated, the object to be heated is sequentially heated. Thus, it is possible to reliably perform heat treatment without unevenness in heat treatment.
[0134]
Moreover, since the peripheral part and the central part are heated twice, it is not necessary to forcibly heat the whole. In other words, it is not necessary to heat more than necessary just because there is uneven heating.
[0135]
Heat treatment can be easily performed by using a plurality of different microwave heating apparatuses.
[0136]
FIG. 10 shows still another embodiment. The same parts as those in FIG. 6 are given the same numbers. In the figure, reference numeral 19 denotes a heater such as a sheathed heater, which is attached to the side wall of the heating casing 1 by a support member 19a.
[0137]
Microwave heating generates heat from the inside, but its surface is covered with a thick packaging container 3b. In order to prevent the generated heat from being taken away by the container 3 b and the surface temperature of the article to be heated 3 being lowered, the periphery of the container is heated by the heater 19.
[0138]
Although the heater 19 in FIG. 10 is electrically heated, high temperature steam may be used.
[0139]
Heating timing of the heater may be simultaneous with microwave heating, or when the heat capacity of the container is large, the heater may be heated prior to microwave heating. Alternatively, the container may be heated before being inserted into the microwave heating device.
[0140]
9 and 10, the change in the shape of the upper part 3a of the container containing the article 3 to be heated is measured by the position sensor 15, and the microwave output or the atmospheric pressure in the heating housing is controlled based on the measurement result. ing. The dotted line portion of the upper part 3a shows the deformation of the container.
[0141]
As mentioned above, although the microwave heating device for the purpose of sterilization was described, it is needless to say that the present invention is not limited to sterilization and can be applied to an object requiring heat treatment exceeding 100 ° C.
[0142]
【The invention's effect】
According to the present invention, since the atmosphere in the place where the object to be heated such as food is stored is heated by the microwave, the moisture is hardly evaporated even when the temperature exceeds 100 ° C., and the heat of evaporation greatly increases the energy. It can be heated to a temperature of 100 ° C. or higher without losing. For pre-packaged foods such as retort foods, it can be adjusted to an external pressure suitable for the temperature despite the difficulty in detecting the food temperature, and is necessary for sterilization without deformation or damage to the food or packaging. It is possible to provide a microwave heating apparatus that can rapidly perform microwave heating to a certain temperature.
[0143]
Further, according to the present invention, the microwave heating device can be heated to a temperature of 100 ° C. or higher without greatly losing energy due to the heat of evaporation of the object to be heated, so that a microwave heating device with good reliability can be provided. .
[0144]
Further, according to the present invention, microwave heating can be quickly performed to a temperature necessary for sterilization by setting the microwave heating time and output together with the pressure adjustment. It can be done quickly with reliability.
[0145]
Since food can be sterilized at high speed, there is no deterioration of the food and the commercial value of the food is not impaired.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a microwave heating apparatus of the present invention.
FIG. 2 is a sectional view of a magnetron according to the present invention.
FIG. 3 is a power supply circuit diagram for driving a magnetron of a microwave heating apparatus according to the present invention.
FIG. 4 is a cross-sectional view showing another embodiment of the microwave heating apparatus of the present invention.
FIG. 5 is a cross-sectional view of a microwave heating apparatus showing an embodiment of the present invention.
FIG. 6 is a cross-sectional view showing another embodiment of the microwave heating apparatus of the present invention.
FIG. 7 is a cross-sectional view of an essential part showing another embodiment of the microwave heating apparatus of the present invention.
FIG. 8 is a cross-sectional view of an essential part showing another embodiment of the microwave heating apparatus of the present invention.
FIG. 9 is a cross-sectional view showing another embodiment of the microwave heating apparatus of the present invention.
FIG. 10 is a cross-sectional view showing another embodiment of the microwave heating apparatus of the present invention.
FIG. 11 is a cross-sectional view showing a conventional microwave heating apparatus.
[Explanation of symbols]
1 Heating case
2 trays
3 Object to be heated
4 Starr
5 Electron tube magnetron
6 Waveguide
7 Gas exhaust section
10 Pressurization system
11,12 cover
13 Temperature sensor
14 Pressure sensor
15 Position sensor

Claims (4)

A heating housing part that houses an object to be heated, a microwave power supply part for supplying microwave power to the heating housing, and a pressure inside the heating housing And a uniformizing means for uniformly heating the object to be heated in the heating casing, and the uniformizing means is supported by a support bar penetrating the heating casing. Te rotated by a drive device disposed outside the heating enclosure, the drive unit is disposed inside becomes higher pressure chamber portion of the pressure from the heating housing, a heating housing said support rods to pass through A microwave heating apparatus, wherein a projection or a choke is provided in a penetrating part. 2. The gas discharge unit according to claim 1, wherein a gas discharge portion is provided in a part of the heating casing, and the pressure in the heating casing is made lower than the pressure in the pressurizing chamber by discharging the gas in the heating casing. A microwave heating apparatus, wherein a heated object is heated by a microwave. In Claim 1, when the said to-be-heated material is inserted in the inside of the said housing | casing for heating, and the microwave heating is performed, the atmosphere around the to-be-heated material is made atmospheric pressure by the said pressurization system part during microwave heating. A microwave heating apparatus characterized by increasing pressure. In Claim 1, when inserting the said to-be-heated object into the inside of the said housing | casing for heating, and performing microwave heating, the atmosphere around the to-be-heated object is made higher than atmospheric pressure by the said pressurization system | strain part. Then, microwave heating apparatus characterized by performing microwave heating.

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