JPH10172753A - Microwave oven - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent abnormal temperature rise of the inside of a machine chamber in which a high-pressure relay for switching capacitance of a high- pressure capacitor is arranged in a multiplied voltage rectifying circuit for driving a magnetron during heater heating cooking. SOLUTION: A control unit 37, in case that a power frequency is 60Hz as specified, always interrupts power of a high-pressure relay 9 arranged in a machine chamber adjacent to a cooking chamber and turns off a normal open contact 9a, thereby reducing capacitance of a high-pressure capacitor 34 in a multiplied voltage rectifying circuit 36 for driving a magnetron 7, and in case that a power frequency is 50Hz that is out of the specification, contacts power of the high-pressure relay 9 only during micro-oven cooking due to the magnetron 7 and turns on the normal open contact 9a, thereby increasing capacitance of the high-pressure capacitor 34. Consequently, in case that the power frequency is 50Hz that is out of the specification, since the high-pressure heater is power-interrupted during heater heating cooking, that magnetizing coil 9C is never conducted and heated, and the inside of the machine chamber does not rise a temperature abnormally even if it is subject to thermal influence of heater heating cooking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave oven capable of heating and cooking by heating in a cooking chamber, and more particularly, to switching the capacity of a high-voltage capacitor in a voltage doubler rectifier circuit for driving a magnetron according to a power supply frequency or the like. About the microwave oven.

[0002]

2. Description of the Related Art In a microwave oven, a high-voltage transformer, a voltage doubler rectifier circuit including a high-voltage capacitor and a high-voltage diode, a magnetron, and the like are arranged in a machine room adjacent to a heating room, and a commercial power supply voltage is boosted by the high-voltage transformer. The secondary side output is double-voltage rectified by a double voltage rectifier circuit and supplied to a magnetron, and microwaves generated by the oscillating operation of the magnetron are supplied into a heating chamber to perform range cooking.

In Japan, there are two types of commercial power supply frequencies, 60 Hz and 50 Hz.
When used at 0 Hz or when a microwave oven with a power supply frequency of 50 Hz is used at a power supply frequency of 60 Hz out of specification, the output voltage of the voltage doubler does not reach the specified voltage, and the output of the magnetron deviates from the set value. And there is a problem that hinders range cooking.

[0004]

For this reason, conventionally, a high-voltage capacitor is constituted by two capacitors, and only one of these two capacitors is used by a high-voltage relay disposed in a machine room. The configuration is such that the capacity of the high-voltage capacitor is switched such that both are used. Specifically, when the power plug of the microwave oven is inserted into the outlet (when the power is turned on), the control device detects the power frequency, and if the power frequency is out of the specification, energizes the high voltage relay. The capacity of the high-voltage capacitor is switched by switching.

[0005] By the way, microwave ovens having a configuration in which a heater for heating the inside of a cooking chamber is provided and which can perform heater heating cooking have become widespread. The heat in the cooking room at that time affects the machine room adjacent to the cooking room. As a result, if the power supply frequency is out of the specification and the high-voltage relay is energized, the machine room becomes abnormal due to the synergistic effect of the heat effect during heater heating and the heating of the excitation coil due to the energization of the high-voltage relay. There is a problem that the temperature rises and adversely affects electrical components in the machine room.

The present invention has been made in view of the above circumstances, and a purpose thereof is to provide a high-voltage relay for switching the capacity of a high-voltage capacitor in a doubler rectifier circuit for driving a magnetron in a machine room. Another object of the present invention is to provide a microwave oven capable of preventing an abnormal temperature rise in a machine room during heating and cooking with a heater.

[0007]

According to a first aspect of the present invention, there is provided a microwave oven having a configuration in which a heater can be heated and cooked in a cooking chamber. A high-voltage relay for switching the capacity of the high-voltage capacitor is provided. The high-voltage relay has a function of turning off the high-voltage relay. Control means for turning off the high-voltage relay during heating by heating is provided. .

According to such a configuration, the high-voltage relay is cut off during heating by heating and does not generate heat.
Even if the inside of the machine room is affected by the heat of the heater heating, the temperature does not rise abnormally. In this case, it is preferable that the control means be configured to control the cut-off of the high voltage relay according to the power supply frequency (claim 2). According to such a configuration, the capacity of the high voltage capacitor is switched according to the power supply frequency. .

According to a third aspect of the present invention, there is provided a microwave oven capable of heating and cooking in a cooking chamber, wherein the capacity of a high-voltage capacitor in a voltage doubler rectifier circuit for driving a magnetron is switched in a machine room adjacent to the cooking chamber. A high-voltage relay is provided for controlling the disconnection of the high-voltage relay in accordance with the power supply frequency. It is characterized in that a control means for setting the state is provided. According to such a configuration, the high-voltage relay is turned off when the heater cooking with a high set temperature is selected, so that the high-voltage relay achieves power saving as compared with the conventional case where the current is always energized. In addition, the frequency of the power cutoff control is reduced, and the generation of noise due to turning on and off can be prevented as much as possible.

According to a fourth aspect of the present invention, there is provided a microwave oven capable of heating and cooking in a cooking chamber, wherein the capacity of a high-voltage capacitor in a voltage doubler rectifier circuit for driving a magnetron is switched in a machine room adjacent to the cooking chamber. A high-voltage relay is provided, and has a function of controlling the cut-off of the high-voltage relay according to the power supply frequency. When the temperature in the cooking chamber exceeds a predetermined temperature during heating by heating, the high-voltage relay is turned off. It is characterized by a configuration in which a control means is provided. According to such a configuration, the high-voltage relay is turned off when the temperature in the cooking chamber exceeds a predetermined temperature during the heating heating cooking, so that the same effect as the third aspect is obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. First,
2 and 3 show the entire configuration of the microwave oven. In FIG. 2, the microwave oven main body 1 is configured by arranging an inner box 3 inside an outer box 2.
It is designed to function as. As shown in FIG. 3, a door 5 is rotatably attached to the outer box 2, and the entire opening of the cooking chamber 4 is opened and closed by the rotation of the door 5. I have.

As shown in FIG. 3, the right side inside the microwave oven main body 1 is located between the outer box 2 and the inner box 3, that is,
A machine room 6 is formed adjacent to the cooking room 4. In the machine room 6, electrical components such as a magnetron 7, a high-voltage transformer 8, a high-voltage relay 9, and a high-voltage capacitor 34 described later are housed. When the magnetron 7 operates, the microwave output from the magnetron 7 is supplied into the cooking chamber 4 via the waveguide 7a.

As shown in FIG. 3, a fan device 10 is accommodated in the machine room 6 behind the magnetron 7. This fan device 10 is configured by attaching a cooling fan 10b composed of an axial fan to a rotating shaft of a fan motor 10a composed of a shading motor.
When “a” is operated, the cooling fan 10 b is rotated, and the cooling air is blown mainly to the electric components in the machine room 6 by the magnetron 7. An intake duct 11 is attached to the magnetron 7, and the wind blown to the magnetron 7 is supplied into the cooking chamber 4 through the intake duct 11, and then discharged outside from an exhaust duct (not shown).

As shown in FIG. 2, the microwave oven main body 1 has an upper heater 1 located at the ceiling and the bottom of the cooking chamber 4.
2 and a lower heater 13 are provided, and when these generate heat, the inside of the cooking chamber 4 is heated. The upper heater 12 is a Milacron heater, and the lower heater 13 is a flat heater. An RT motor 14 is provided at the bottom of the microwave oven main body 1, and a turntable 15 is attached to a rotation shaft of the RT motor 14.

As shown in FIG. 2, an operation panel 16 is provided on the entire surface of the microwave oven main body 1 in front of the machine room 6, and the operation panel 16 has an automatic cooking key, Operation unit 17 having manual cooking key, start key, etc.
And a display 18 for performing various displays.
In this case, the automatic cooking keys in the operation unit 17 are “shukan”, “toast”, “cookie”, “cutlet”,
An automatic cooking menu such as "fried" or "gratin" is selected, and a manual cooking key is used to set a cooking mode (range cooking, toaster cooking, open cooking, grill cooking), cooking time, cooking temperature, and the like. It is for doing. In addition, a thermistor 19 serving as a temperature detecting unit is provided on the upper part of the right side plate of the inner box 3, facing the inside of the cooking chamber 4.

The electrical configuration will now be described with reference to FIG. The power plug 20 is inserted and connected to an outlet (not shown), which is a 100-volt commercial power supply.
And a power switch 24 connected in series with a door switch 23, and the other terminal is connected to a power supply line 27 through a normally open contact 26a of a door switch 25 and a first relay 26 in series.
It is connected to the. A monitor switch 28 is connected between the power supply line 24 and a common connection point of the door switch 25 and the normally open contact 26a.

In this case, the thermal switch 22 detects the temperature of the magnetron 7, and is turned off when the detected temperature reaches an abnormal set temperature. The door switches 23 and 25 are turned off when the door 5 is opened, and the monitor switch 28 is turned off when the door 5 is closed.

A parallel circuit of the interior light 29 and the fan motor 10a is connected between the power supply lines 24 and 27. Here, the interior light 29 is provided in the microwave oven main body 1 so as to illuminate the inside of the cooking chamber 4. A series circuit of the upper heater 12 and the normally open contact 30a of the second relay 30, a series circuit of the lower heater 13 and the normally open contact 31a of the third relay 31, and RT A series circuit of the motor 14 and the normally open contact 32a of the fourth relay 32 is connected.

Further, a series circuit of the normally open contact 33a of the fifth relay 33 and the primary coil 8a of the high voltage transformer 8 is connected between the power supply lines 24 and 27, respectively. One terminal of the secondary coil 8b of the high-voltage transformer 8 is connected to the anode of the magnetron 7 and grounded,
Both terminals of the cathode serving as a heater of the magnetron 7 are connected to both terminals of the secondary coil 8 c of the high-voltage transformer 8.

The high-voltage capacitor 34 is composed of two capacitors 34a and 34b, the first capacitor 34a is set to, for example, 0.69 μF, and the second capacitor 34a is set to 0.69 μF.
b is set to, for example, 0.30 μF. In the first capacitor 34a, one terminal is connected to the other terminal of the secondary coil 8b of the high-voltage transformer 8, and the other terminal is connected to one terminal of the cathode of the magnetron 7 and a high-voltage diode. It is connected to the anode of the magnetron 7 via 35.

In the second capacitor 34b,
One terminal is connected to one terminal of the first capacitor 34a via the normally open contact 9a of the high voltage relay 9, and the other terminal is directly connected to the other terminal of the first capacitor 34a. Note that these capacitors 34a, 34b
Are connected in parallel with resistors 34c and 34d, respectively.
The high voltage capacitor 34 and the high voltage diode 35 constitute a voltage doubler rectifier circuit 36.

The control device 37 as a control means is mainly composed of a microcomputer, and its output terminals are connected to the exciting coils 9C, 26C, 30C of the relays 9, 26, 30, 31, 32, and 33, respectively. , 31C, 3
2C and 33C are connected. For simplification of the drawing, the actual connection of the exciting coils 26C, 30C, 31C, 32C and 33C is omitted. Further, the output terminal of the control device 37 is connected to the display 18, and the operation unit 17 and the thermistor 19 are connected to each input terminal.

In the step-down transformer 38, both terminals of the secondary coil 38b are connected to a power supply terminal of the control device 37, and one terminal of the primary coil 38a is
It is connected to a common connection point between the thermal switch 22 and the door switch 23, and the other terminal of the primary coil 38 a is connected to the other terminal of the power plug 20. in this case,
The control device 37 includes a secondary coil 38b of the step-down transformer 38.
Is rectified and converted to a constant voltage to obtain a control DC power supply, and the power supply frequency is detected from the AC output of the secondary coil 38b.

Next, the operation of this embodiment will be described with reference to the flowchart shown in FIG. 4. The microwave oven of this embodiment is set to a power supply frequency of 60 Hz. When the power plug 20 is inserted and connected to an outlet (not shown), the control device 37 obtains a control DC power supply from the secondary output of the step-down transformer 38 and starts operation (starts). First, the control device 37 shifts to the processing step S1 of “initialization (all relays off)”.
A predetermined initialization operation is performed, and the relays 26, 30 to 33 as well as the high voltage relay 9 are turned off (off). Accordingly, since the excitation coils 9C, 26C, 30C to 33C of the relays 9, 26, 30 to 33 are not energized, the normally open contacts 9a, 26a, 30a to 33 are not energized.
a is off. Then, in the processing step S1, the control device 37 detects the power supply frequency from the secondary side output of the step-down transformer 38.

Next, the control device 37 proceeds to step S2 for determining "50 Hz?", Where it determines whether or not the power supply frequency detected in step S1 is 50 Hz. Is 50 Hz out of specification, the determination is "YES", and the process proceeds to the determination step S3 of "range cooking?". In this determination step S3, the control device 37 determines whether or not the cooking selected or set by the automatic cooking key or the manual cooking key of the operation unit 17 is the range cooking by the magnetron 7, and when the determination is "NO". Then, the process proceeds to the determination step S4 of “Heater heating cooking?”.

The control device 37 determines at step S4
It is determined whether the cooking selected or set by the automatic cooking key or the manual cooking key of the operation unit 17 is heater heating cooking (toaster cooking, open cooking, grill cooking) using one or both of the upper heater 12 and the lower heater 13. If the determination is "NO", the process returns to the determination step S3. That is, when the user does not select or set cooking using the automatic cooking key or the manual cooking key of the operation unit 17, the control device 37 repeats the determination steps S3 and S4.

If the user selects or sets the range cooking using the automatic cooking key or the manual cooking key of the operation unit 17, the control device 37 determines whether or not the range cooking has been performed.
When the process proceeds to step S3, "YES" is determined, and the process proceeds to the determination step S5 of "start cooking?" The control device 37
In this determination step S5, it is determined whether or not the start key of the operation section 17 has been operated. If "NO", this determination step S5 is repeated, and if "YES", "relay 9, 26, 32 on" is set. Move to processing step S6.

In the processing step S6, the control device 37
The energizing coil 9C of the high voltage relay 9 is energized to make the normally open contact 9a
Is turned on, and the exciting coils 26C and 32C of the first and fourth relays 26 and 32 are energized to turn on the normally open contacts 26a and 32a. Therefore, when the normally open contact 9a of the high voltage relay 9 is turned on, the second capacitor 34b is connected in parallel to the first capacitor 34a in the high voltage capacitor 34, and the capacity of the high voltage capacitor 34 is only one of the first capacitor 34a. The switching is performed so as to increase the capacity.

The normally open contact 26a of the first relay 26
Is turned on, the fan motor 10a and the interior lamp 29 are energized. Therefore, the inside lamp 29 is turned on to illuminate the inside of the cooking chamber 4, and the fan motor 10a is operated to rotate the cooling fan 10b. When the normally open contact 32a of the fourth relay 32 is turned on, the RT motor 14
Operates to rotate the turntable 15.

After that, the control device 37 proceeds to the processing step S7 of “turn on the relay 33 after T seconds”.
After a lapse of second (for example, 100 msec), the fifth relay 33
Is turned on to turn on the normally open contact 33a. As a result, a power supply voltage is applied to the primary coil 8a of the high-voltage transformer 8, and a high voltage is induced in the secondary coil 8b. The voltage induced in the secondary coil 8b is voltage-double rectified by the voltage doubler rectifier circuit 36,
, And the magnetron 7 oscillates to generate microwaves and supply them to the cooking chamber 4, thereby starting microwave cooking.

The control device 37 further proceeds to step S8 for judging "cooking complete?", In which the cooking time of the range cooking selected or set by the automatic cooking key or the manual cooking key of the operation unit 17 ends. It is determined whether or not the determination has been made. If "NO", this determination step S8 is repeated. After that, when the cooking time is over and the determination in step S8 is “YES”, the control device 37 proceeds to the “relay 33 off” processing step S9, and turns off the exciting coil 33C of the fifth relay 33. And the normally open contact 33
Turn off a. As a result, the supply of the power supply voltage to the primary coil 8C of the high-voltage transformer 8 is stopped, the magnetron 7 stops oscillating, and the range cooking ends.

Then, the control device 37 shifts to the processing step S10 of "Relay 8, 26, 32 off after T seconds", and
High voltage relay 9, first and fourth relays 26 and 32
Of the excitation coils 9C, 26C, and 32C, and the normally open contacts 9a, 26a, and 32a are turned off. Therefore,
When the normally open contact 9a is turned off, the second capacitor 3 with respect to the first capacitor 34a in the high-voltage capacitor 34 is turned off.
The parallel state of 4b is released, and the capacity of the high-voltage capacitor 34 returns to the small capacity of only the first capacitor 34a.
The normally open contacts 26a and 32a of the first and fourth relays 26 and 32 are turned off, so that the fan motor 10
a, the interior light 29 and the RT motor 14 are turned off, and their respective operations are stopped. After finishing the above operation, the control device 37 returns to the determination step S3.

On the other hand, if the user selects or sets the heater heating cooking (toaster cooking, open cooking or grill cooking) using the automatic cooking key or the manual cooking key of the operation unit 17, the control device 37 determines whether or not to perform the determination step S.
When the process proceeds to step S4, "YES" is determined, and the process proceeds to the "heater heating cooking" processing step (subroutine) S11. In the processing step S11, the control device 37 supplies power to the excitation coil 26C of the first relay 26 to turn on the normally open contact 26a, and also controls the excitation coils 30C and 31C of the second and third relays 30 and 31 to turn on. One or both are energized to turn on one or both of the normally open contacts 30a and 31a, and if necessary, energize the excitation coil 32C of the fourth relay 32 to energize the normally open contacts 32a.
Turn on.

As a result, the fan motor 10a and the interior lamp 29 are operated, and one or both of the upper heater 12 and the lower heater 13 are energized to generate heat, and if necessary, the RT motor 14 is energized. Turntable 1
5, the heater heating cooking selected or set by the automatic cooking key or the manual cooking key of the operation unit 17 is executed. Then, in this heater heating cooking, the controller 37 refers to the temperature detected by the thermistor 19, and refers to the second and third relays 30 and 31.
Of one or both of the exciting coils 30C and 31C, thereby causing one or both of the upper heater 12 and the lower heater 13 to intermittently generate heat, thereby controlling the temperature in the cooking chamber 4 to the set temperature. . After that, when the set cooking time ends, the control device 37 turns off (turns off) all the relays, ends the cooking, and returns to the determination step S3.

During the heating and cooking of the heater, the high-voltage relay 9 is turned off in the processing step S2 or the processing steps S9 and S10, so that no heat is generated by energization of the exciting coil 9C.

When the detected power supply frequency is 60 Hz as specified, the control device 37 initializes
"NO" is determined in the determination step S2 of "50 Hz?", And the determination steps S12 and S13 similar to the determination steps S3 and S4 are repeated. When the user selects or sets the range cooking using the automatic cooking key or the manual cooking key of the operation unit 17, the control device 37
Determines “YES” when the process proceeds to the determination step S12, and proceeds to the determination step S14 of “Cooking started?”. The control device 37 determines in step S14 that “YE
S, the process proceeds to step S15 of "ON of relays 26, 32, and 33", and the exciting coils 26 of the first, fourth, and fifth relays 26, 32, and 33 are turned on.
C, 32C and 33C are energized to open normally open contacts 26a, 3
Turn on 2a and 33a.

As a result, range cooking is performed in the same manner as described above. In this case, since the high-voltage relay 9 is in a cut-off state and its normally open contact 9a is turned off, the cooking in the voltage doubler rectifier circuit 36 is performed. The capacity of the high-voltage capacitor 34 is the first capacitor 34a according to the specified power supply frequency of 60 Hz.
Only has a small capacity.

Thereafter, when the cooking time is over and the determination at step S16 is "YES", the control device 37 sets the "relays 26, 32, 33 off" processing step S.
17 and the relays 26, 32 and 33 are turned off,
Thus, the range cooking is ended, and the process returns to the determination step S12.

On the other hand, when the user selects or sets the heater heating cooking (toaster cooking, open cooking or grill cooking) using the automatic cooking key or the manual cooking key of the operation unit 17, the control device 37 determines whether or not to perform the determination step S.
13, the determination is “YES”, the process proceeds to the “heater heating” processing step (subroutine) S18, the same heater heating cooking as described above is executed, and the process returns to the determination step S12. When the heater is heated, the high voltage relay 9
Has been cut off.

As described above, according to the present embodiment, when the control device 37 is initialized (when the power is turned on), the high-voltage relay 9 is turned off, so that a power supply frequency of 50 Hz other than the specified power supply frequency of 60 Hz is used. When the heating is performed, the high voltage relay 9 is turned off and the exciting coil 9C is not energized to generate heat during the heating and cooking of the heater. Even if it is affected, it is possible to prevent the temperature inside the machine room 6 from rising abnormally, and there is no adverse effect on other electrical components disposed inside the machine room 6.

In order to prevent the abnormal temperature rise in the machine room 6 during the heating and cooking by the heater, the cooking room 4 and the cooking room 4 are connected in order to prevent the heat in the cooking room 4 from being transmitted into the machine room 6 as much as possible. It is also conceivable to enhance the heat shielding structure with a heat shielding body, a heat insulating body, and the like between the machine room 6. However, in this case, a problem that causes an increase in the price occurs. Since the abnormal temperature rise in the machine room 6 at the time of heating with the heater is prevented, the above-described problem does not occur.

According to this embodiment, the high voltage relay 9
In the case of a power supply frequency of 50 Hz out of specification, when the range cooking is selected or set, it is turned on and off, so that the power consumption is reduced as compared with the conventional case where the high voltage relay is always on. The high-voltage relay 9 is turned off only when cooking in a microwave oven.
When turned off, noise can be prevented as much as possible.

In addition, according to the present embodiment, during range cooking when the power supply frequency is out of specification and the frequency is 50 Hz, the processing of steps S6 and S7 and steps S9 and S10 causes the fifth relay 33 to operate normally when starting range cooking. The ON point of the open contact 33a is delayed by T seconds (100 msec) from the ON point of the normally open contact 9a of the high voltage relay 9, and when the range cooking ends, the OFF point of the normally open contact 9a of the high voltage relay 9 is set to the fifth point.
Is delayed by T seconds from the time when the normally open contact 33a of the relay 33 is turned off.
Can be avoided under a high voltage, and the occurrence of a spark due to the ON / OFF of the normally open contact 9a can be reliably prevented.

Next, a second embodiment of the present invention will be described with reference to FIG. The microwave oven according to the second embodiment has a power supply frequency of 50 Hz, and a normally closed contact 9b is used instead of the normally open contact 9a of the high voltage relay 9 shown in FIG. Then, the control device 37 (see FIG. 1)
When the power supply frequency is 60H other than the specified power supply frequency of 50 Hz, the processing shifts to the judgment step S3 in FIG. 1 and thereafter, the power is cut off through the excitation coil 9C of the high voltage relay 9 to make the normally closed contact 9b Is turned off and on.

That is, when the power supply frequency is 60 Hz other than the specified power supply frequency of 50 Hz, the control device 37 always energizes (turns on) the high voltage relay 9 only at the time of range cooking as in the above-described embodiment. Closed contact 9
b, the capacity of the high-voltage capacitor 34 is reduced to only the first capacitor 34a. Conversely, when the power supply frequency is the specified power supply frequency of 50 Hz, the high-voltage relay 9 is turned off (off). By turning on the normally closed contact 9b, the capacity of the high-voltage capacitor 34 is increased to the large capacity of the first and second capacitors 34a and 34b. Therefore,
The second embodiment has the same operation and effect as the first embodiment.

The present invention is not limited to the embodiment described above and shown in the drawings, and the following modifications and extensions are possible. The controller 37 has a power supply frequency of 6
In the case of 0 Hz, when the detected power frequency is 50 Hz out of the specification when the power is turned on, the capacity of the high voltage relay 34 is set by turning on the high voltage relay 9 and turning on the normally open contact 9 a (see FIG. 1). Is set to a large capacity, and when heater heating cooking such as "cutlet" or "fly" having a high set temperature is selected during heater heating cooking, the high voltage relay 9 is turned off (turned off) to turn off the exciting coil 9C.
May be configured to cut off the power supply to the power supply. In this case, when the detected power frequency is the specified power frequency of 60 Hz,
Needless to say, the high voltage relay 9 is always kept in a disconnected state.

The same applies to the case where the specified power supply frequency is 50 Hz. When the power supply is turned on and the detected power supply frequency is 60 Hz out of the specification, the control device 37 operates.
Is turned on and the normally closed contact 9b (see FIG. 5) is turned off to reduce the capacity of the high voltage relay 34. When the heater heating cooking with a higher set temperature is selected during the heater heating cooking, The high voltage relay 9 is turned off (turned off) to turn off the excitation coil 9C. Even with such a configuration, the first and second
The same effect as that of the embodiment can be obtained.

In the case where the specified power supply frequency is 60 Hz and the detected power supply frequency is 50 Hz out of the specification when the power supply is turned on, the control device 37 sets the high-voltage relay 9 to the energized (on) state to set the normally open contact 9a. (See FIG. 1) By turning on, the capacity of the high voltage relay 34 is increased,
When the temperature in the cooking chamber 4 detected by the thermistor 19 serving as the temperature detecting means exceeds a predetermined temperature (for example, 200 ° C.) during the heating heating, the high voltage relay 9 is turned off (turned off) to switch the excitation coil 9C. You may comprise so that energization may be turned off. In this case, when the detected power supply frequency is the specified power supply frequency of 60 Hz, the high-voltage relay 9 is, of course, always in a cut-off state.

The same applies to the case where the specified power supply frequency is 50 Hz. When the power supply is turned on, and the detected power supply frequency is 60 Hz out of the specification, the control device 37 operates.
Is turned on and the normally closed contact 9b (see FIG. 5) is turned off to reduce the capacity of the high voltage relay 34, and the temperature in the cooking chamber 4 detected by the thermistor 19 during heater heating cooking is reduced. When the temperature exceeds a predetermined temperature (for example, 200 ° C.), the high voltage relay 9 is turned off (turned off) to turn off the power to the exciting coil 9C. With such a configuration, the same effects as those of the first and second embodiments can be obtained.

In each of the above embodiments, the capacity of the high voltage capacitor 34 is switched by controlling the passage of the high voltage relay 9 according to the power supply frequency. However, the present invention is not limited to this. Voltage doubler rectifier 3
The present invention can be generally applied to the case where the capacity of the high voltage condenser 34 needs to be switched, and in any case, the high voltage relay 9 is turned off at the time of heating by heating.

[0051]

As described above, the present invention has the following effects. According to the microwave oven according to claim 1 or 2, the high-voltage relay for switching the capacity of the high-voltage capacitor in the voltage doubler rectifier circuit for driving the magnetron is turned off during the heating and cooking of the heater. Does not generate heat during heater heating cooking, and can prevent an abnormal rise in temperature even if the inside of the machine room is affected by the heat of the heater heating cooking, and does not adversely affect electrical components in the machine room.

According to the third aspect of the present invention, the high-voltage relay for switching the capacity of the high-voltage capacitor in the voltage doubler rectifier circuit is turned off when heater heating with a high set temperature is selected during heating and cooking. As a result, power saving can be achieved as compared with the conventional high-voltage relay, which is always energized, and the frequency of power cut-off control of the high-voltage relay is reduced, resulting in noise associated with ON and OFF. Generation can be prevented as much as possible.

According to the fourth aspect of the present invention, the high-voltage relay for switching the capacity of the high-voltage capacitor is turned off when the temperature in the cooking chamber exceeds a predetermined temperature during heating and cooking. Therefore, the same effect as the third aspect can be obtained.

[Brief description of the drawings]

FIG. 1 is an electrical configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a front view of the microwave oven with a door removed.

FIG. 3 is a longitudinal sectional side view showing a machine room side of a microwave oven.

FIG. 4 is a flowchart for explaining the operation.

FIG. 5 is an electrical configuration diagram of a main part showing a second embodiment of the present invention.

[Explanation of symbols]

In the drawing, 1 is a microwave oven main body, 4 is a cooking room, 6 is a machine room, 7 is a magnetron, 8 is a high voltage transformer, 9 is a high voltage relay, 12 is an upper heater, 13 is a lower heater, 19 is a thermistor, and 34 is a high pressure. Capacitors 34a and 34b are first and second capacitors, 35 is a high voltage diode, 3
Reference numeral 6 denotes a voltage doubler rectifier circuit, and 37 denotes a control device (control means).

Claims (4)

[Claims] 1. A microwave oven capable of heating and cooking by heating in a cooking chamber, comprising: a high-voltage relay provided in a machine room adjacent to the cooking chamber, for switching the capacity of a high-voltage capacitor in a voltage doubler rectifier circuit for driving a magnetron; A microwave oven provided with a control means for controlling power cut through the high voltage relay and for turning off the high voltage relay during heating by heating. 2. The microwave oven according to claim 1, wherein the control means is configured to control power cut-off according to a power supply frequency. 3. A microwave oven capable of performing heater heating cooking in a cooking chamber, wherein the high-voltage relay is disposed in a machine room adjacent to the cooking chamber and switches a capacity of a high-voltage capacitor in a voltage doubler rectifier circuit for driving a magnetron. And control means for controlling power cutoff of the high-voltage relay in accordance with a power supply frequency, and for turning off the high-voltage relay when heater heating at a high set temperature is selected during heater cooking. A microwave oven comprising: 4. A microwave oven capable of heating by heating in a cooking chamber, wherein the high-voltage relay is disposed in a machine room adjacent to the cooking chamber and switches a capacity of a high-voltage capacitor in a voltage doubler rectifier circuit for driving a magnetron. Control means for controlling power cutoff of the high-voltage relay according to the power supply frequency, and for turning off the high-voltage relay when the temperature in the cooking chamber exceeds a predetermined temperature during heater heating cooking; A microwave oven comprising: