JP5435000B2 - Microwave processing equipment - Google Patents

Description

  The present invention relates to a microwave processing apparatus that amplifies microwave power using a non-insulated AC-DC converter.

  Conventionally, in this type of microwave processing apparatus, for example, there is an apparatus using an AC-DC converter that changes a commercial power source using a transformer to a DC power source (see, for example, Patent Document 1).

  Conventionally, the AC-DC converter of this type of microwave processing apparatus has an insulation transformer and constitutes insulation, and the secondary side of the insulation transformer is electrically floating, and is very easy to handle by grounding the GND potential. Met. FIG. 12 is a system block diagram showing a configuration of a conventional microwave processing apparatus described in Patent Document 1. In FIG. As shown in FIG. 12, an insulating transformer is provided, and the carrier frequency is converted to 50 to 60 kHz for the purpose of removing current harmonic components by a PFC circuit, so that the insulating transformer is supposed to be downsized.

JP 2008-060017 A

  However, in the above-described conventional configuration, in principle, there are factors that can reduce the size of the insulation transformer because the carrier frequency is high, but for example, about 1500 W for home use using a 100 V commercial power source, In equipment used in restaurants kitchens, etc., in devices handling huge power of 3000 W, transformers that insulate them and magnetically transmit power require large cores and bobbins, and there are no general-purpose parts. It had the problem of very inefficient design and development, where one to ten original designs had to be custom-made by parts manufacturers.

  Furthermore, it has a non-insulated AC-DC converter, has an insulation transformer-less configuration, and supplies a DC voltage from the non-insulated AC-DC converter to an amplifier that amplifies the microwave supplied from the oscillator, via a coaxial line. The cavity connected and the radiating part that supplies microwaves to the microwave processing device have the problem that the user is electrocuted by charging the metal part that is lively charged to the commercial power supply and possibly touched by humans. It was.

In order to solve the above-described conventional problems, the microwave processing apparatus of the present invention includes a metal cavity for storing an object to be heated and preventing leakage of the microwave to the outside, and opening and closing the object to be heated freely. When closed, the opening of the cavity is sealed to prevent leakage of the microwave to the outside, the door switch that cuts off the power line in conjunction with the opening of the door, the oscillator that generates the microwave, and the oscillator An amplifier for amplifying the microwave, a power supply unit for supplying power to the amplifier, a coaxial line for transmitting the microwave power of the amplifier, and a radiation unit for radiating the microwave amplified by the amplifier, It consists of an AC-DC converter that is non-isolated and does not have an isolation transformer, and its output is coupled to the radiating section and cavity by a coaxial line. Is a charging part and secures insulation from the metal part that may be touched by the user. When the door is opened, the power supply to the AC-DC converter is cut off by the door switch. It becomes the structure used as a part.

  As a result, the metal parts that can be touched by the person when the door is closed are not insulated because the insulation is secured, and the metal parts that can be touched by the door switch when the door is opened are not. Since it becomes a charging part, it becomes possible to implement | achieve the safe microwave processing apparatus without the danger of an electric shock also as a transformerless structure which consists of a non-insulation type AC-DC converter.

  The microwave processing apparatus of the present invention can provide a small and economical microwave processing apparatus that does not generate an electric shock even when a power source composed of a transformerless non-insulated AC-DC converter is used. Furthermore, since the microwave processing measure of the present invention uses a non-insulated AC-DC converter and is transformerless, the system can be greatly simplified.

The system block diagram which shows the whole structure of the state with the closed door of the microwave processing apparatus in the 1st Embodiment of this invention The system block diagram which shows the whole structure of the state which the door of the microwave processing apparatus in the 1st Embodiment of this invention opened The system block diagram which shows the whole structure of the state with the closed door of the microwave processing apparatus in the 2nd Embodiment of this invention The system block diagram which shows the whole structure of the state which the door of the microwave processing apparatus in the 2nd Embodiment of this invention opened. The system block diagram which shows the whole structure of the state which the door of the microwave processing apparatus in the 3rd Embodiment of this invention opened. The circuit diagram which shows the AC-DC converter of the microwave processing apparatus in the 1st Embodiment of this invention Principle explanatory drawing which shows the AC-DC converter operation | movement of the state which the transistor of the microwave processing apparatus in the 1st Embodiment of this invention is ON Principle explanatory drawing which shows the AC-DC converter operation | movement of the state which the transistor of the microwave processing apparatus in the 1st Embodiment of this invention is OFF Timing chart of each waveform for explaining circuit operation of microwave processing apparatus according to first embodiment of the present invention Sectional drawing which shows the coaxial line applied to the microwave processing apparatus in the 1st Embodiment of this invention The fragmentary sectional view which shows the structure of the choke part of the microwave processing apparatus in the 3rd Embodiment of this invention System block diagram showing the configuration of a conventional microwave processing apparatus

A first invention is a microwave processing apparatus for generating a microwave to heat an object to be heated, the metal cavity for storing the object to be heated and preventing leakage of the microwave to the outside, Opening and closing the object to be heated so that it can be stowed and closed, the opening of the cavity is sealed to prevent leakage of the microwave to the outside, the door switch that cuts off the power line in conjunction with the opening of the door, and the microwave Oscillator that generates, amplifier that amplifies the microwave generated by the oscillator, power supply unit that supplies power to the amplifier, coaxial line that transmits the microwave power of the amplifier, and microwaves that are amplified by the amplifier radiate The amplifier is composed of an AC-DC converter that is non-isolated and does not have an isolation transformer, and its output is coupled to the radiant part and the cavity by a coaxial line, and is closed Sometimes radiating portion and the cavity is a metal part that may touch the and user becomes live parts are prevented from electrical shock by ensuring insulation. When the door is opened, the power supply to the AC-DC converter is cut off by the action of the door switch, so that the radiating portion and the cavity become a non-charging portion. Therefore, the insulation of the metal part that can be touched by humans is always ensured. Therefore, the risk of electric shock can be avoided even with a transformerless structure comprising a non-insulated AC-DC converter.

  A second invention is a microwave processing apparatus for generating a microwave to heat an object to be heated, the metal cavity for storing the object to be heated and preventing leakage of the microwave to the outside, A door that opens and closes the object to be heated and closes to close the opening of the cavity to prevent leakage of the microwave to the outside, a door switch that cuts off the power line in conjunction with the opening of the door, and a microwave An oscillator for generating a microwave, an amplifier for amplifying the microwave generated by the oscillator, a power supply for supplying power to the amplifier, a coaxial line for transmitting the microwave power of the amplifier, and an insulation from the cavity And a radiating section coupled by the coaxial line and radiating microwaves into the cavity, the amplifier being non-insulated and having no isolation transformer A A DC converter, and when the door is closed, the radiating part becomes a charging part and secures insulation from a metal part that may be touched by the user, and when the door is opened, the AC switch is operated by the door switch. In order to cut off the power supply to the converter, the radiating part is a microwave processing device configured to be a non-charging part. In particular, the radiating part is insulated from the cavity so that the entire cavity becomes the charging part. And the insulation configuration becomes extremely simple.

  According to the third aspect of the invention, in particular, by providing the choke part in the insulating part between the cavity and the radiating part of the second aspect, it is possible to remarkably reduce the leaked radio wave from the inside of the cavity, and dramatically improve the EMI performance. Can do.

  In the fourth aspect of the invention, in particular, by providing a plurality of configurations that radiate using the radiating portion of any one of the first to third aspects, radio waves radiated from the plurality of radiating portions interfere with each other. Various standing wave distributions can be obtained and the heating condition of the heated part can be freely controlled.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a system block diagram showing the overall configuration of the first embodiment of the present invention.

  In FIG. 1, power is transmitted from the commercial power source 1 to the device. The door switch 2 is a contact point between the hot line and the cold line of the commercial power source 1 and can be opened and closed to store the object to be heated 13. When the door 9 is closed, the door switch 2 is interlocked with the door 9 that seals microwaves. When the contact is open and closed, the contact closes. The sine wave voltage of the commercial power source 1 is converted from the four diodes into a unidirectional power source by the full wave rectifier 3. Although the step-down chopper 4 will be described in detail later, the unidirectional power supply is converted into a low-voltage DC voltage. In this example, three potentials Vdd, Vcc, and Vss are created. Here, a block surrounded by a dotted line has a function of an AC-DC converter 5 that converts the commercial power source 1 into a DC voltage.

The oscillator 6 generates a source oscillation microwave signal from Vcc and Vss by a crystal oscillator and a PLL. The amplifier 7 receives the output of the oscillator 6 via the CC1 of the coaxial line 8, amplifies the power, and distributes it to the CC2 and CC3 of the coaxial line 8 with a power of about 53 dBm. 10 is emitted. The cavity 10 accommodates the article to be heated 13 and confines the microwave radiated from the radiating unit 12 in the cavity 10. The microwave oscillated from the radiating unit 12 is absorbed by the object to be heated 13 and is dielectrically heated. Further, the door 9 is closed in FIG. 1 and abuts against the front surface of the cavity 10 to confine the microwave in the cavity 10 and prevent leakage of the microwave. Since the contact surface of the door 9 with the cavity 10 is made of resin, it is insulated from the cavity 10, but the contact surface becomes electrically infinite by an inherent (not shown) choke mechanism. Therefore, the microwave does not leak from the gap.

  Here, CC <b> 2 and CC <b> 3 of the coaxial line 8 penetrate the cavity 10. FIG. 10 is a cross-sectional view of the coaxial line 8. The coaxial line 8 is composed of a dielectric 26 formed of Teflon (registered trademark) around the metal core 24 and an outer surface of the metal covering the cylinder. The cover 25 is configured so that the characteristic impedance is 50Ω.

  Returning to FIG. 1, the coaxial line 8 passes through the cavity 10 to come into contact with the cavity 10 to be at the same potential. Here, the outer sheath 25 is charged to Vss, and the core wire 24 is charged to Vdd. The periphery of the cavity 10 is covered with a metal body 14 and is at ground potential. When the door 9 is opened, the cavity 10 is charged with the commercial power supply potential because the door switch 2 that closes the contact in conjunction with the door 9 transmits power to the subsequent circuits. .

  FIG. 6 is a detailed circuit diagram of the AC-DC converter 5. The commercial power source 1 is input to the full-wave rectifier 3 via the door switch 2 and becomes a unidirectional voltage and is output to the step-down chopper 4. The unidirectional voltage input to the step-down chopper 4 is converted into a direct current by the electrolytic capacitor A17. It comprises a transistor 19 that is ON / OFF driven by a control unit 21, an inductor 20 that stores energy, a diode 23 that rectifies current, and an electrolytic capacitor B 18 that smoothes a voltage output to a load 22.

  Now, the operation of the step-down chopper 4 will be described with reference to the operation principle explanatory diagram when the transistor 19 in FIG. 7 is ON, with reference to the operation explanatory diagrams showing the current / voltage waveforms of the respective parts in FIG.

  When the transistor 19 is ON (timing A in FIG. 9A), a current flows along the path indicated by the thick arrow. Currents IL and Iout flow through the inductor 20 and the load 22. Here, as shown in FIG. 9C, energy is stored in the inductor 20 and IL flows out (timing B in FIG. 9C). Due to the characteristics of the inductor 20, the current IL monotonously increases in a ramp waveform. Here, the transistor 19 is turned OFF by the control signal from the control unit 21 (timing C in FIG. 9A).

  Further, the operation will be described with reference to an operation principle explanatory diagram when the transistor 19 in FIG. 8 is OFF.

  The current flowing through the inductor 20 from the timing D in FIG. 9C monotonously decreases in a ramp waveform. The decrease continues until the control unit 21 turns off the transistor 20 (the timing F in FIG. 9C). This operation is repeated after this as one cycle. Iout becomes a direct current as shown in FIG. The voltages Vin and Vout in FIGS. 7 and 8 at this time have a relationship as shown in FIG. 9B, and Vin is smaller than Vout. When the duty ratio is small in FIG. 9A, Vout decreases, and when the duty ratio is large, Vout increases. The controller 21 detects Vout and controls the duty ratio to obtain a desired step-down voltage.

Here, between the cavity 10 which is a live part and the body 14 which the user may touch, as shown in FIG. 1, the insulating spacer a 11a, the insulating spacer b 11b, and the insulating spacer c 11c and 11d which are insulating spacers d are inserted,
Even if the AC-DC converter 5 is a non-insulated type, the body 14 is grounded to the ground potential, so that there is no safety at all due to electric shock.

  FIG. 2 is a system block diagram when the door 9 according to the first embodiment of the present invention is opened. However, since the contact of the door switch 2 linked with the door 9 is open, Since the power source 1 is completely insulated, the cavity 10 is also floated in terms of potential, and naturally the body 14 is at ground potential, and even when the door 9 is opened, even if the person touches the cavity 10, an electric shock is caused. It has a safe configuration with no danger.

  As shown in the first embodiment, by providing a plurality of radiating portions 12 (two in the first embodiment), the oscillation frequency and the mutual phase difference can be changed, so that the constant in the cavity 10 can be changed. Since the standing wave distribution can be freely changed, concentrated heating and local heating can be realized without a radio wave stirring mechanism, so that the heating performance is improved.

(Embodiment 2)
FIG. 3 is a system block diagram showing the overall configuration in the second embodiment of the present invention. In addition, the same code | symbol is provided to the same component as the said Embodiment 1, and description is abbreviate | omitted.

  FIG. 3 shows a normal state in which the door 9 is closed. The microwave is radiated into the cavity 10 to heat the article 13 to be heated. Here, the contact of the door switch 2 interlocked with the door 9 is in a closed state, and power is supplied from the commercial power source 1 to the device.

  Here, the core hole 24 of the coaxial line 8 and the core wire 24 of the coaxial line 8 are coupled to the radiating portion 12 in the cavity 10 with an appropriate clearance through the small hole 15 formed in the cavity 10. Therefore, the cavity 10 is not grounded but grounded. Although a small amount of microwave leakage occurs from this clearance portion, since the casing is covered with a metal body 14, the user is not exposed to the leakage microwave, and safety against electric shock is ensured.

  FIG. 4 is a system block diagram showing the overall configuration in the second embodiment of the present invention when the door 9 is opened. Also in this case, the cavity 10 which is an exposed metal part that may be touched by a person when the door 9 is opened is safe because it is grounded. Furthermore, since the double insulation structure of the contact of the open contact of the door switch 2 and the clearance of the small hole 15 is used here, the safety is further improved.

  In addition, since the cavity 10 which is a large structure is not a live part, the exposed metal part existing in the machine room between the cavity 10 and the body 14 is more than the distance specified by the technical regulations for the purpose of insulation. The troublesome design restriction of taking an insulation distance is eliminated, installation and arrangement of parts inside the machine room, lead wire harness, etc., and bundling fixing members such as insulation locks are unnecessary, design freedom increases, design efficiency and unnecessary Therefore, it is possible to provide a microwave processing apparatus that is easy to manufacture.

(Embodiment 3)
FIG. 5 is a system block diagram showing the overall configuration in the third embodiment of the present invention. In addition, the same code | symbol is provided to the same component as the said Embodiment 1 and Embodiment 2, and description is abbreviate | omitted.

  FIG. 5 illustrates the time when the door 9 is opened. The gap between the small hole 15 and the cavity 10 secures a moderately small distance that does not cause an electric field and does not hinder workability. However, the microwave leakage is configured to leak even though the amount is small. Here, the choke portion 16 is provided in the gap to prevent microwave leakage.

  FIG. 11 shows a partial configuration diagram of a choke portion for preventing leakage of microwaves. In FIG. 11, a portion surrounded by a dotted line is the choke portion 16. The coaxial wire 8 is inserted into the small hole 15, and the core wire 24 protrudes further from the wall surface of the cavity 10 and is joined to the radiating portion 12 including the metal patch antenna 31. The radio wave entering from the gap of the small hole 15 enters the choke 27 from the B part, the impedance is zero in the A part, the impedance is infinite in the B part, and the radio wave transmitted in the direction of the choke 28 is greatly attenuated. Further, the choke 28 is further attenuated in the same manner as the choke 27, so that the total attenuation is about -40 dB. Therefore, the radio wave leaking out of the cavity 10 is lower than the limit value of the technical regulations, and the radio wave leaks into the machine room. Is almost zero. When the choke portion 16 is not present, a semiconductor IC or the like having a small radio wave in the machine room and inferior in immunity may malfunction due to EMC in-house poisoning, but the choke 27, 28, 29, 30 functions. Therefore, the danger can be eliminated and a highly reliable microwave processing apparatus can be provided.

  As described above, the microwave processing apparatus according to the present invention realizes transformer-less using a non-insulated AC-DC converter, so that the entire system is small and simple, and manufacturing can be simplified. Therefore, it can be applied to all microwave processing apparatuses that drive a microwave power amplifier using a DC power source.

2 Door Switch 5 AC-DC Converter 6 Oscillator 7 Amplifier 8 Coaxial Line 9 Door 10 Cavity 12 Radiation Part 16 Choke Part

Claims (4)

A microwave processing apparatus that generates microwaves and heats an object to be heated.
A metal cavity for storing the object to be heated and preventing leakage of microwaves to the outside;
A door that opens and closes the object to be heated freely and closes the opening of the cavity to prevent leakage of microwaves to the outside.
A door switch that cuts off the power line in conjunction with the opening of the door;
An oscillator that generates microwaves;
An amplifier for amplifying the microwave generated by the oscillator;
A power supply for supplying power to the amplifier;
A coaxial line for transmitting the microwave power of the amplifier;
A radiation section that radiates microwaves amplified by the amplifier, and
The amplifier is a non-insulated AC-DC converter having no isolation transformer, and its output is coupled to the radiating portion and the cavity by the coaxial line, and the radiating portion and the cavity are charged when the door is closed. The radiating portion and the cavity are provided to ensure insulation from a metal portion that can be touched by a user and to cut off power supply to the AC-DC converter by the door switch when the door is opened. A microwave processing apparatus configured to be a non-charging part. A microwave processing apparatus that generates microwaves and heats an object to be heated.
A metal cavity for storing the object to be heated and preventing leakage of microwaves to the outside;
A door that opens and closes the object to be heated freely and closes the opening of the cavity to prevent leakage of microwaves to the outside.
A door switch that cuts off the power line in conjunction with the opening of the door;
An oscillator that generates microwaves;
An amplifier for amplifying the microwave generated by the oscillator;
A power supply for supplying power to the amplifier;
A coaxial line for transmitting the microwave power of the amplifier;
A radiating portion formed with insulation with respect to the cavity and coupled by the coaxial line to radiate microwaves into the cavity;
The amplifier is a non-insulated AC-DC converter having no insulating transformer, and when the door is closed, the radiating part becomes a charging part and secures insulation from a metal part that a user may touch, A microwave processing apparatus configured such that when the door is opened, the radiation unit is a non-charging unit in order to cut off the power supply to the AC-DC converter by the action of the door switch. The microwave processing apparatus according to claim 2, further comprising a choke portion that prevents leakage of microwaves from an insulating portion between the cavity and the radiation portion. The microwave processing apparatus according to any one of claims 1 to 3, further comprising at least one oscillator, an amplifier, a power supply unit, a coaxial line, and a radiation unit.