KR100270873B1 - Inrush current removing apparatus of microwave oven - Google Patents

Abstract

Disclosed is an inrush current removing device for a microwave oven having an overheat prevention function. The present invention disclosed is driven by a high voltage transformer, a rectifying unit for rectifying the AC flowing in the primary coil of the high voltage transformer to a low voltage direct current, and a low voltage direct current passing through the rectifying unit, generated by the high voltage transformer when the initial power is turned on. Inrush current removal unit for removing the inrush current and the overheat protection unit is driven to a low voltage passed through the rectifier to block overheating of the high-voltage transformer. The overheat protection unit includes a temperature switch that is turned on / off according to the temperature of the high-voltage transformer. Therefore, by using a low-cost component driven at a low voltage to eliminate the inrush current generated in the microwave when the initial power is applied, and further equipped with a temperature switch to prevent overheating of the high-voltage transformer, the production cost and the consumption accordingly In addition to saving power, it also effectively prevents overheating of high voltage transformers.

Description

Inrush current removal device of microwave oven with overheat protection

The present invention relates to an inrush current removing device of a microwave oven having an overheat prevention function, and more particularly, by using a low-cost component driven at a low voltage to remove the inrush current generated in the microwave when the initial power is applied. The present invention relates to an inrush current removing device of a microwave oven having an overheat prevention function for preventing overheating of a high voltage transformer.

In general, a microwave oven is a device for heating / cooking food using microwaves, and a conventional high voltage transformer and a magnetron are provided. This high voltage transformer generates a predetermined high voltage to drive the magnetron, and the magnetron emits microwaves of a predetermined frequency (about 2450 MHz) in an enclosed space in which food is stored. Microwaves emitted in this way vibrate the water molecules contained in the food, molecular friction heat is generated in accordance with the vibration of the water molecules is to heat / cook food.

1 is a partially cutaway perspective view illustrating a conventional microwave oven, and FIG. 2 is a circuit diagram of FIG. 1.

According to Figure 1, the cabinet 20 forming the appearance of the microwave oven is divided into a left and right space, one side is provided with a cooking chamber 22, the front is open, the other side lamp (2), fan motor (3), magnetron ( The apparatus room 23 in which various electric appliances, such as MGT), a high voltage transformer (HVT), and a high voltage capacitor (HVC), is installed is provided. In the front of the apparatus room 23, an operation panel 25 for operating a microwave oven and displaying the state thereof is provided.

In addition, the door 21 that opens and closes the front of the cooking chamber 22 is rotatably fixed to one side of the cabinet 20, and a rotating plate 24 in which the food to be cooked is placed is installed in the cooking chamber 22. The rotating plate 24 is rotated by the drive motor 4 (shown in FIG. 2) and the gears of the bottom surface of the cabinet 20 to increase cooking efficiency.

According to Figure 2, the first and second alternating lines (L1) (L2) for inputting the normal AC power source (110V AC or 220V) through the noise filter (1) at both ends of the high-voltage transformer (HVT) primary coil Connected. The noise filter 1 is composed of a main fuse FUSE1, capacitors C1 to C3, a coil inductor L, a resistor R1, and the like, and the operation of the noise filter is the same as that of a conventional noise filter. The detailed description will be omitted.

The magnetron temperature switch TCO1, the first door switch SW1, and the monitor switch SW4 are connected to the first alternating line L1, and the cabinet temperature switch TCO2 and the timer switch are connected to the second alternating line L2. SW3), second door switch SW2 and inrush switch 6b are connected. The magnetron temperature switch TCO1 and the cabinet temperature switch TCO2 block overheating generated in the magnetron MTG and the cabinet 20 of the microwave oven, respectively. The first and second door switches SW1 and SW2 and the monitor switch SW4 are turned on and off according to the opening / closing state of the door 21 to perform a safety function of the microwave oven.

One side of the monitor switch SW4 is connected to the primary coil of the high voltage transformer HVT, and the other side thereof is connected to the second door switch SW2 via the monitor fuse FUSE2. In addition, the inrush coil 6a is connected in parallel to the monitor switch SW2 to turn on / off the inrush switch 6b. The current limiting resistor R2 is connected in parallel to the inrush switch 6b. As the current limiting resistor R2, a normal cement resistor is used. In addition, the cooking chamber lamp 2, the fan motor 3, the driving motor 4, and the timer 5 are connected between the first alternating line L1 and the second alternating line L2.

The timer switch SW3 applies AC power AC to a primary coil of the cooking lamp 2, the fan motor 3, the driving motor 4, the timer 5, and the high voltage transformer HVT. The inrush switch 6b and the current limiting resistor R2 are operated by the inrush coil 6a when the initial power is turned on to remove the inrush current caused by the high counter electromotive force generated in the primary coil of the high voltage transformer HVT. do.

The secondary coil of the high voltage transformer (HVT) is connected to a magnetron (MGT), a high pressure fuse (H.V.FUSE), a high pressure capacitor (HVC) and a high voltage diode (HVD). The high voltage capacitor (HVC) and the high voltage diode (HVD) double the output voltage of the high voltage transformer (HVT), and the magnetron (MGT) is driven at the high voltage (typically, about 4000V) that is supplied to generate a predetermined microwave. . The high voltage fuse (H.V.FUSE) cuts off the overcurrent on the secondary coil side of the high voltage transformer (HVT).

The operation of the conventional microwave oven configured as described above is as follows.

The user opens the door 21 and places the food to be cooked in the state in which the cooking chamber 22 is opened in the rotary dish 24 inside the cooking chamber 22 through the front of the cabinet 20 and places the door 21. Close it. At this time, the first and second door switches SW1 and SW2 and the monitor switch SW4 that are normally turned off are turned on.

In this state, the user operates a timer knob (not shown) of the operation panel 25 to set / input cooking time and cooking output according to the type of food. Therefore, the AC power AC input through the first and second alternating lines L1 and L2 when the timer switch SW3 is turned on is the cooking chamber lamp 2, the fan motor 3, and the driving motor 4. , To the primary coil of the timer 5 and the high voltage transformer HVT.

At this time, when the timer switch SW3 is turned on, a high inrush current is instantaneously generated by the characteristics of the inductive load of the high voltage transformer HVT, and the inrush current is a resistor connected in parallel to the inrush switch 6b. Removed by (R2). After a predetermined time has elapsed, a current is conducted to the inrush coil 6a so that the inrush switch 6b is turned on, and the current flows through the inrush switch 6b during normal operation.

The high voltage transformer (HVT) induces the voltage supplied to the primary coil to the secondary coil to supply the high voltage to the high voltage capacitor (HVC), the high voltage diode (HVD) and the magnetron (MGT), and the high voltage capacitor (HVC), The diode HVD doubles the high voltage, and the magnetron MTG generates a predetermined microwave and emits it into the cooking chamber 22.

The lamp 2 illuminates the inside of the cooking chamber 22, the fan motor 3 cools various circuit components in the apparatus chamber 23, and the drive motor 4 is a rotary plate 24 inside the cooking chamber 22. By rotating so that the microwaves are evenly incident on the food, the food is properly heated / cooked during the desired cooking time. In addition, when overcurrent and consequent overheating occur in the high voltage transformer (HVT) while the cooking is performed, the high voltage fuse (HVFUSE) of the secondary coil side of the high voltage transformer (HVT) is melted to cut off the driving current. do.

However, such a conventional microwave oven generally uses a high voltage transformer (HVT) to boost the AC voltage of 120 / 230V and obtain a high voltage. In such a microwave circuit, when the initial power is turned on, the above high voltage is used. Due to the characteristics of the inductive load of the transformer (HVT), a high inrush current is generated instantaneously. This inrush current adversely affects the circuit components, and even more severely may cause component damage. Therefore, in order to prevent such inrush current, an expensive inrush current prevention relay (SSR: solid state) composed of an inrush coil and a switch is used. The circuit is composed of relay and high resistance resistor. Accordingly, the conventional microwave oven has a problem of increasing production cost and power consumption by applying such an inrush relay for preventing inrush current and a resistor.

In addition, the high-voltage fuse that blocks overheating and overcurrent on the secondary coil side of the high-voltage transformer has a problem of having to determine specifications for different current capacities, and a temperature difference due to a difference in blow-down characteristics of the fuse. There was another problem that the current was not cut correctly.

Accordingly, an object of the present invention is to solve the problems of the prior art, by using a low-cost component driven by a low voltage to remove the inrush current generated in the microwave when the initial power is applied, and the temperature switch The present invention provides an inrush current removing device for a microwave oven having an overheat prevention function to prevent overheating of a high voltage transformer.

1 is a partially cutaway perspective view showing a conventional microwave oven,

2 is a circuit diagram of FIG.

Figure 3 is a circuit diagram showing a preferred embodiment of the inrush current removing device of the microwave oven having an overheat protection function according to the present invention.

Explanation of symbols on the main parts of the drawings

100: rectifier 110: inrush current removing unit

120: overheat prevention unit 111: inrush coil

112: inrush switch HVT: high voltage transformer

TCO3: Temperature Switch

Features of the inrush current removing device of the microwave oven having an overheat protection function according to the present invention for achieving this object, the high-voltage transformer, the rectifier for rectifying the AC flowing in the primary coil of the high-voltage transformer to a low-voltage direct current, It is driven by a low-voltage direct current through the rectifier, the inrush current removal unit to remove the inrush current generated by the high-voltage transformer when the initial power is turned on and is driven at a low voltage through the rectifier to block the overheating of the high-voltage transformer Includes overheat protection. The overheat protection unit includes a temperature switch that is turned on / off according to the temperature of the high-voltage transformer.

Therefore, by using a low-cost component driven at a low voltage to eliminate the inrush current generated in the microwave when the initial power is applied, and further equipped with a temperature switch to prevent overheating of the high-voltage transformer, the production cost and the consumption accordingly In addition to saving power, it also effectively prevents overheating of high voltage transformers.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the inrush current removing device of the microwave oven having an overheat prevention function according to the present invention, the same components as in the prior art will be described with the same reference numerals.

Figure 3 is a circuit diagram showing a preferred embodiment of the inrush current removing device of the microwave oven having an overheat protection function according to the present invention.

According to FIG. 3, the first and second alternating lines L1 and L2 for inputting an ordinary AC power source (110V AC or 220V) are connected to both ends of the HVT primary coil via the noise filter 1. Connected. The magnetron temperature switch TCO1, the first door switch SW1, and the monitor switch SW4 are connected to the first alternating line L1, and the cabinet temperature switch TCO2 and the timer switch are connected to the second alternating line L2. SW3) and the second door switch SW2 are connected. One side of the monitor switch SW4 is connected to the primary coil of the high voltage transformer HVT, and the other side thereof is connected to the second door switch SW2 via the monitor fuse FUSE2. The cooking chamber lamp 2, the fan motor 3, the driving motor 4, and the timer 5 are connected between the first alternating line L1 and the second alternating line L2. The secondary coil of the high voltage transformer (HVT) is connected to the magnetron (MGT), the high pressure fuse (HVFUSE), the high pressure capacitor (HVC) and the high voltage diode (HVD), the microwave is configured as described above through the prior art As shown.

However, the present invention is characterized in that the rectifier 100 is connected to the primary coil of the high-voltage transformer (HVT), and the inrush connected to the first and second alternating lines (L1) (L2) via the rectifier (100). It includes a current removing unit 110, and an overheat prevention unit 120 to be driven by a low-voltage direct current through the rectifier 100, to block overheating of the high-voltage transformer (HVT).

The rectifier 100 includes a resistor R10, a diode D12, and a capacitor C10. The resistor R10 reduces the voltage flowing in the primary coil of the high voltage transformer HVT, and the diode D12 rectifies the current passing through the resistor R10 in one direction, and the capacitor C10 rectifies the diode. Charge / discharge the voltage input via (D12).

The inrush current removing unit 110 includes an inrush coil 111, an inrush switch 112, and a plurality of diodes D10 and D12. The inrush coil 111 is driven by a low voltage direct current passing through the rectifying unit 100, the inrush switch 112 is turned on / off by driving the inrush coil 111, and a plurality of diodes D10 are provided. D12 selectively branches the direction of the current passing through the inrush coil 111 to the first or second alternating lines L1 and L2.

Overheat prevention unit 120 is composed of a temperature switch (TCO3) that is turned on / off according to the temperature of the high-voltage transformer (HVT).

If described in more detail the action of the preferred embodiment according to the present invention configured as follows.

The user opens the door 21 and places the food to be cooked in the state in which the cooking chamber 22 is opened in the rotary dish 24 inside the cooking chamber 22 through the front of the cabinet 20 and places the door 21. Close it. At this time, the first and second door switches SW1 and SW2 and the monitor switch SW4 that are normally turned off are turned on.

In this state, the user operates a timer knob (not shown) of the operation panel 25 to set / input cooking time and cooking output according to the type of food. Therefore, the AC power AC input through the first and second alternating lines L1 and L2 when the timer switch SW3 is turned on is the cooking chamber lamp 2, the fan motor 3, and the driving motor 4. , To the primary coil of the timer 5 and the high voltage transformer HVT.

Here, the moment the timer switch (SW3) is turned on, a high inrush current is instantaneously generated by the characteristics of the inductive load of the high voltage transformer (HVT), the inrush current is the rectifier 100 and the inrush current removing unit 110 Is removed by).

In more detail, first, the current flowing through the first door switch SW1 and the monitor switch SW4 through the primary coil of the high voltage transformer HVT is decompressed through the resistor R10 of the rectifier 100, and a diode It is rectified by passing in one direction through (D12). This current flows toward the second door switch SW2 through the inrush coil 111 and the diode D11 of the inrush current removing unit 110. At this time, the inrush current is removed by the resistance component of the inrush coil 111.

In addition, the inrush switch 112 is turned on as a current is conducted to the inrush coil 111. Therefore, the current input through the second door switch SW2 flows through the inrush switch 112 to the primary coil of the high voltage transformer HVT. In addition, the inflow coil 111 and the diode D10 of the resistor R10, the diode D12, and the inrush current removing unit 110 of the rectifier 100 are sequentially flowed toward the first door switch SW1. do.

Therefore, since the inrush switch 112 is kept on because the current continues to be conducted to the inrush coil 111, the high voltage transformer HVT passes through the first door switch SW1 and the monitor switch SW4 during normal operation. The current flowing in the primary coil of) passes through the inrush switch 112 to the second door switch SW2. In addition, the capacitor C10 connected in parallel to the inrush coil 11 charges / discharges the voltage input through the diode D10 of the rectifier 100 to correct the voltage fluctuation.

In this way, after the initial inrush current is removed, normal microwave operation is performed. That is, the high voltage transformer (HVT) induces the voltage supplied to the primary coil to the secondary coil to supply high voltage to the high voltage capacitor (HVC), the high voltage diode (HVD) and the magnetron (MGT), and the high pressure capacitor (HVC). The high-voltage diode HVD doubles the high voltage, and the magnetron MTG generates a predetermined microwave and emits the microwave into the cooking chamber 22. The lamp 2 illuminates the inside of the cooking chamber 22, the fan motor 3 cools various circuit components in the apparatus chamber 23, and the drive motor 4 is a rotary plate 24 inside the cooking chamber 22. By rotating so that the microwaves are evenly incident on the food, the food is properly heated / cooked during the desired cooking time.

On the other hand, when an overcurrent and thus overheating occurs in the high voltage transformer HVT while cooking is performed in this way, the temperature switch TCO3 connected to one end of the resistor R10 of the rectifying unit 100 is connected to the high voltage transformer HVT. The overheat of) is immediately detected and turned off, so the driving current is cut off. Therefore, by using a low-cost component driven at a low voltage to remove the inrush current generated in the microwave when the initial power supply, and further provided with a temperature switch (TCO3) to prevent overheating of the high-voltage transformer (HVT), In addition to reducing the production cost and thus the power consumption, the overheating of the high-voltage transformer (HVT) is effectively prevented.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims set forth.

As described above, according to the inrush current removing device of the microwave oven having an overheat prevention function according to the present invention, an expensive inrush current prevention relay operated as a commercial AC power supply to remove the inrush current generated in the microwave when the initial power is applied. (SSR) and cement resistors are excluded, while inrush current is effectively reduced by using low-voltage direct-current components such as resistors, diodes, and DC relays, which constitute the rectifier and inrush current elimination. By removing it, it is possible to reduce the production cost and thus the power consumption.

In addition, by eliminating the high-voltage fuse that cuts off the overheat and over-current of the high-voltage transformer secondary coil, by applying a low-temperature temperature switch, the hassle of having to determine the specifications of each current capacity and the fuse characteristics of the fuse At the same time, there are other effects that can prevent overheating of the high-voltage transformer while eliminating problems caused by the high voltage transformer.

Claims (2)

High voltage transformer; A rectifier for rectifying the alternating current flowing in the primary coil of the high voltage transformer into a low voltage direct current; An inrush current removal unit driven by a low voltage direct current passing through the rectifying unit to remove an inrush current generated by the high voltage transformer when the initial power is turned on; And An inrush current removing device of a microwave oven having an overheating prevention function, characterized in that it is driven at a low voltage passing through the rectifying unit, and overheating blocking unit blocks overheating of the high voltage transformer. The method of claim 1, wherein the overheat prevention unit, Inrush current removal device of the microwave oven having a overheat prevention function, characterized in that it comprises a temperature switch that is on / off according to the temperature of the high-voltage transformer.