How the various components of the microwave oven work
Furnace cavity
The furnace cavity is a microwave cavity, which is a space for turning microwave energy into heat to heat food. In order to uniformly heat the food in the cavity, a special device is arranged in the cavity of the microwave oven. The microwave oven was originally produced with a metal fan sheet on the top of the furnace chamber, that is, a microwave agitator to interfere with the propagation of microwaves in the furnace chamber, thereby making the food heating more uniform. At present, a glass turntable driven by a micro motor is installed at the bottom of the cavity of the microwave oven, and the heated food is placed on the turntable and rotated together with the turntable around the motor shaft to make relative movement with the high frequency electromagnetic field in the furnace. To achieve the purpose of uniform heating of the food in the furnace. The original automatic lifting type turntable in China makes the heating more uniform and the cooking effect is more ideal. The flat furnace cavity reflects the microwave through the inner wall of the cavity to achieve uniform heating.
Furnace door
The furnace door is the import and export of food, and is also an important part of the microwave oven cavity. It is very demanding and must not allow the microwave to leak out. The furnace door consists of a metal frame and a glass viewing window. There is a layer of metal microporous mesh in the glass interlayer of the observation window, which can see the food through it and prevent microwave leakage. Since the mesh size of the metal mesh in the glass interlayer is precisely calculated, it can completely block the penetration of microwaves. Titanium film is also widely used as a material for microwave oven doors.
In order to prevent microwave leakage, the microwave oven's switching system consists of multiple safety interlock micro switch devices. If the oven door is not closed, the microwave oven cannot be operated, and the microwave oven does not work, so there is no problem of microwave leakage.
In order to prevent the microwave from leaking from the gap between the furnace door and the cavity after the oven door is closed, a anti-flow groove structure is arranged around the oven door of the microwave oven, or a material capable of absorbing microwaves, such as made of silicone rubber, is installed. The door seal can absorb a small amount of microwaves that may leak. The chute is a profiled groove structure provided in the door, which has the function of guiding the microwave reverse phase. At the entrance of the choke, the microwave is offset by its reverse reflected wave so that the microwave does not leak.
Because the door seals are prone to breakage or aging, the anti-leakage effect is reduced. Therefore, most microwave ovens now use a chute structure to prevent microwave leakage, and silicone rubber door seals are rarely used. The chute structure is a stable and reliable method for preventing microwave leakage from the principle of microwave radiation.
Electrical circuit
The electrical circuit is divided into three parts: a high voltage circuit, a control circuit and a low voltage circuit.
(a) High-voltage circuit: The circuit after the secondary winding of the high-voltage transformer is a high-voltage circuit, which mainly includes a magnetron, a high-voltage capacitor, a high-voltage transformer, and a high-voltage diode.
(b) Magnetron: The magnetron is the heart of a microwave oven from which microwave energy is generated and emitted. The magnetron requires high pulsating DC anode voltage and a cathode voltage of about 3 to 4V when operating. A voltage doubler rectifier circuit composed of a high voltage transformer, a high voltage capacitor, and a high voltage diode provides an operating voltage for the magnetron that satisfies the above requirements.
(c) Low-voltage circuits: The circuit between the primary winding of the high-voltage transformer and the power inlet of the microwave oven is a low-voltage circuit, which also includes a control circuit. Mainly include fuses, thermal circuit breaker protection switches, interlocking micro switches, lighting, timers and power splitter switches, turntable motors, fan motors, etc.
Timer
Microwave ovens generally have two timing modes, namely mechanical timing and computer timing. The basic function is to select the set working time. After the set time has elapsed, the timer automatically cuts off the main circuit of the microwave oven.
Power splitter
The power divider is used to adjust the average working time of the magnetron (ie, the ratio of the working and stopping time when the magnetron is intermittently operated), thereby achieving the purpose of adjusting the average output power of the microwave oven. Mechanically controlled microwaves typically have 3 to 6 scale files, while computer-controlled microwave ovens have 10 adjustment gears.
Interlocking micro switch
Interlocking microswitches are an important set of safety devices for microwave ovens. It has multiple interlocking functions, which are controlled by the door opening button of the oven door or the door opening button on the door handle. When the furnace door is not closed or the furnace door is open, the circuit is disconnected and the microwave oven is stopped.
Thermal circuit breaker
Thermal circuit breakers are components used to monitor the operating temperature of a magnetron or furnace chamber. When the operating temperature exceeds a certain limit, the thermal circuit breaker will immediately cut off the power supply and stop the microwave oven.
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