KR20000075153A - Relay apparatus for a preventing inrush current of a microwave oven - Google Patents

Abstract

PURPOSE: An inrush current protection relay is provided to reduce manufacturing cost and simplify manufacturing procedures. CONSTITUTION: An integrated type inrush current protection relay(100) for controlling a voltage apply state for a microwave oven, comprises a driving member driven by a magnetic force generated by a control of a micro computer of microwave oven, and an inrush current protection relay switch(RY10) which is turned on or off by the driving force from the driving member so as to supply a power voltage to the high voltage driving unit, a lamp, a fan motor and a driving motor of the micro wave oven. The inrush current protection timer switch has operation terminals(a,b) which are firstly connected to a first terminal(c) of which one end is connected to a positive temperature coefficient thermistor(PTC), and connected to a second terminal(d) after elapse of a predetermined time period.

Description

Relay device for a preventing inrush current of a microwave oven}

The present invention relates to a microwave oven, and more particularly, to a relay device for preventing inrush current of a microwave oven using an integrated relay.

As is well known, a microwave oven prepares food by friction heat generated by molecular motion inside the microwave by irradiating microwaves generated from a magnetron in a state where food is placed in a cooking chamber.

1 is an exploded perspective view of a conventional microwave oven as shown above. According to this, the conventional microwave oven 10 can be largely divided into the control unit 20, the high-pressure driving unit 30, and the heating unit 40 in terms of its structure.

The control unit 20 is provided with a plurality of operation keys 21 for setting the cooking time and cooking output of the microwave, and the plurality of operation keys 21 are placed on the back of the control unit 20 with a microcomputer 9. ) And various circuit components are connected on the PCB board 6 mounted thereon. The microcomputer 9 of the PCB substrate 6 performs the cooking operation by turning on or off the driving state of the microwave oven in accordance with the time and output set by each operation key 21. In addition, the control unit 20 is provided with a display window 24 for displaying various cooking times and cooking conditions, and a door lever 25 for opening and closing the door 43 to be described later.

The high-pressure driving unit 30 is a preheating voltage required for the operation of the magnetron (MGT) for generating a microwave, the waveguide (not shown) for guiding the microwave generated from the magnetron (MGT) to the cooking chamber 41, the magnetron (MGT) It consists of high voltage transformer (HVT), high voltage condenser (HVC), high voltage diode (HVD), magnetron (MGT), cooling fan (3) for cooling and lamp (2) for illuminating cooking chamber (41). have.

And, the heating unit 40 to take in and out the food in the cooking chamber 41 and the cooking plate 41 and the cooking chamber 41 to allow the food in the interior of the cooking chamber 41 to form a closed space. Is composed of a door 43 for. The rotating plate 42 is rotated by the drive motor 4 of the bottom surface, so that the microwaves are evenly incident on the surface of the food, and the door 43 is opened and closed by the door lever 25 described above.

In addition, Figure 2 is a circuit diagram showing the overheat prevention circuit of the conventional microwave oven.

As shown, the first and second power supply lines L1 and L2 for inputting the normal AC power source AC 230V pass through the noise filter 1 at both ends of the high voltage transformer HVT primary coil 7a. Is connected to. Here, the noise filter 1 is composed of a main fuse FUSE1, capacitors C1 to C3, an inductor L, a resistor R1, and the like. The noise filter 1 functions as a power supply line L1 and L2. Since it is the same as a conventional noise filter that cuts out a high frequency wave propagated to the outside through, a detailed description thereof will be omitted.

The first power switch L1 is turned on / off according to the temperature of the magnetron MTG to prevent overheating of the magnetron, and the first door switch is turned on or off according to the opening / closing state of the door 43. The monitor switch SW _MT for monitoring the opening / closing state of the SW1 and the door 43 is connected in series.

In addition, the second power supply line L2 includes a cooking temperature sensor TCO2 that is turned on / off according to the temperature of the cooking chamber 41 to prevent overheating of the cooking chamber 41, and a power relay RY3 that turns the main power on / off. In series with each other, an inrush relay RY2 for preventing inrush current is connected to the power relay RY3 in parallel. In addition, the current limiting resistor R2 is connected to the inrush switch SW _IR . As the current limiting resistor R2, a cement resistor of high resistance is usually used.

The power relay RY3 and the inrush relay RY2 together with the respective coils constitute respective relay elements, and the power relay RY3 and the inrush relay RY2 are disposed on the PCB substrate 6. , By the respective relay coils controlled by the microcomputer 9.

Here, the power relay RY3 and the inrush relay RY2 are first turned on by the inrush relay RY2 by appropriate control of the microcomputer 9, and after a predetermined time, for example, 20 to 40 ms has passed. The power relay RY3 operates. Therefore, after the high inverse electromotive force inrush current generated by the high voltage transformer HVT is consumed by the current limiting resistor R2 and the inrush relay RY2 immediately after the initial power is applied, the power relay RY3 is turned on. Overload of driving circuit and damage of microwave oven can be prevented in advance.

The heater 8 is connected between the first power line L1 and the second power line L2 in front of the noise filter 1. In addition, a heater relay RY1 for turning on / off the heater 8 and a heater temperature sensor TCO3 for preventing overheating of the heater 8 are connected in series with the heater 8.

In addition, between the first power line L1 and the second power line L2 at the rear end of the noise filter 1, the lamp 2, the fan motor 3, the driving motor 4 and the low voltage transformer LVT are provided. In addition, the main relay RY4 for turning on / off the lamp 2, the fan motor 3, and the driving motor 4 is connected. Here, the lamp 2 and the fan motor 3 are driven by a power supply voltage (AC 230V), the drive motor 4 is a low voltage (AC 21 ~ 24V) drawn from one side of the fan motor (3) coil Driven.

In addition, the low voltage transformer LVT step-downs the power supply voltage and supplies a DC voltage to the PCB substrate 6 through a rectification means (not shown). The PCB substrate 6 includes the microcomputer 1 shown in FIG. 1. In addition, a plurality of circuit elements driven by the DC voltage are disposed.

In addition, the heater relay RY1 and the main relay RY4 together with each coil constitute a respective relay element, and each relay coil disposed on the PCB substrate 6 and controlled by the microcomputer 9. Is turned on / off.

In addition, the other side of the monitor switch (SW _MT ), one side of which is connected to the primary coil (7a) of the high-voltage transformer (HVT), one side of the low-voltage transformer (LVT) and the monitor fuse (FUSE2) through the cooking temperature sensor ( TCO2). The monitor fuse FUSE2 is disposed on the PCB substrate 6, and a second door switch SW2 is provided on the PCB substrate 6, which is turned on / off according to the opening / closing state of the door 43. The second door switch SW2 transmits the open / closed state of the door 43 to the microcomputer 9.

Therefore, such a conventional microwave oven cooks using microwaves and cooks using a heater by selectively turning on / off respective relays RY1 to RY4 under the control of the microcomputer 9 provided on the PCB substrate 6. Can be performed together or separately.

For example, in the microwave function, the microcomputer 9 first turns on the main relay RY4, the inrush relay RY2 and the power relay RY3 through respective coils on the PCB substrate 6. Accordingly, since the contacts of the main relay RY4 are turned on, the lamp 2, the fan motor 3, and the driving motor 4 of the microwave oven are operated, and the inrush relay RY2 and the power relay RY3 are sequentially operated. By turning on, by inducing power to the high-pressure driving unit 30 emits microwaves from the magnetron (MGT) included in the high-pressure driving unit 30 it is possible to cook food.

On the other hand, in the heater function, the operation of the above components are the same, except that the microcomputer 9 turns off the inrush relay RY2 and the power relay RY3 and turns on the heater relay RY1. Instead of the magnetron MGT, the heater 8 is operated to perform grill cooking.

Here, the high voltage transformer (HVT) is a device that receives AC power in one circuit and supplies power to another circuit by an electromagnetic induction action, and normally inputs a commercial AC voltage 230V and boosts the voltage to a high voltage and outputs the same. Do it. Therefore, the high voltage transformer HVT inputs a commercial AC voltage of about 230V through the primary coil 7a and boosts it to a high voltage of about 2000V through the secondary coil 7b. In addition, the secondary coil 7b of the high voltage transformer HVT is connected to the magnetron MTG via a high pressure fuse H.V.FUSE, a high pressure capacitor HVC, and a high voltage diode HVD. The high voltage diode HVD and the high voltage capacitor HVC double the high voltage to about 4000V and supply the same to the magnetron MGT. In addition, the filament coil 7c preheats the magnetron MTG to prevent the non-oscillation of the magnetron. In addition, the high voltage fuse (H.V.FUSE) prevents overcurrent of the high voltage transformer (HVT) secondary coil 7b or overheating of the high voltage transformer (HVT).

As described above, the overheat prevention circuit of the conventional microwave oven is a very useful device to properly drive the high-pressure driving unit 30 and the heater 8 at a time desired by the user, and also to prevent overload and overheating.

However, the conventional microwave oven as described above requires a plurality of relays for preventing inrush current, and a rather complicated microcomputer control technique for sequentially connecting the respective relays. There has been a problem in that manufacturing costs of microwave ovens increase due to mounting and wiring processes of a plurality of relays.

Accordingly, the present invention has been made to solve the above problems, the object of the present invention is to reduce the manufacturing cost of the microwave oven by applying an integrated relay to prevent inrush current, the inrush current prevention relay of the microwave simplified the process To provide a device.

1 is an exploded perspective view showing a conventional microwave oven,

2 is a circuit diagram showing a relay device of a conventional microwave oven,

3 is a circuit diagram showing a relay device for preventing inrush current of a microwave oven according to the present invention;

4 to 6 is a plan sectional view showing in detail the relay switch structure and the operation state of the present invention.

<Description of the symbols for the main parts of the drawings>

2: lamp 3: fan motor

4: driving motor 6: PCB board

9: micom 30: high pressure drive unit

100: integral relay 113: first fixing piece

114: second fixing piece 115: movable piece

120: drive means 123: relay coil

121: hinge portion 122: pressing member

100: integrated relay RY10: inrush current prevention relay switch

PTC: PTC thermistor a, b: Operation terminal

c: first terminal d: second terminal

A: Output terminal B: Input terminal

The characteristics of the relay device for preventing the inrush current of the microwave oven according to the present invention for achieving the above object, the high-voltage driving unit, the lamp, the fan motor and the driving motor under the control of the microcomputer provided on the PCB substrate. In forming an integrated relay for adjusting the application state of the power supply voltage, the integrated relay; Drive means driven by a magnetic force generated by the control of the microcomputer; And on / off by driving of the driving means to provide a power supply voltage to the high voltage driving unit, the lamp, the fan motor, and the driving motor, wherein when the switch is turned on, the movable terminal is first connected to a first terminal having a PTC thermistor connected to one end thereof. It consists of a relay switch for preventing inrush current connected to the second terminal after a predetermined time.

The inrush current preventing relay switch may include a first fixing piece having a fixed end connected to an output terminal via the PTC thermistor and having the first terminal at the other end thereof; A second fixing piece having a fixed end connected to the output terminal and having the second terminal at a second end having a predetermined distance from the first terminal; And a movable piece having an input terminal formed at a fixed end and the movable terminal sequentially connected to the first terminal and the second terminal by a driving force of the driving means at the other end.

The driving means may include: a relay coil configured to generate a magnetic force by conducting current through the microcomputer; And a pressing member driven about a hinge part by the magnetic force of the relay coil.

Accordingly, the present invention is equipped with an integrated relay including an inrush current prevention relay switch in which a power relay and an inrush relay are integrated in the microwave oven, thereby effectively blocking the inrush current of the microwave oven and improving workability by eliminating the wiring process. And manufacturing cost is reduced.

The above objects and advantages of the present invention will become more apparent from the preferred embodiments of the present invention described below with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a circuit diagram of a relay device for preventing inrush current of a microwave oven according to the present invention.

As shown, the first and second power supply lines L1 and L2 for inputting the normal AC power source AC 230V pass through the noise filter 1 at both ends of the high voltage transformer HVT primary coil 7a. Is connected to. The first power switch L1 is turned on / off according to the temperature of the magnetron MTG to prevent overheating of the magnetron, and the first door switch is turned on or off according to the opening / closing state of the door 43. (SW1) and the monitor switch (SW _MT ) for monitoring the opening and closing state of the door 43 is connected in series, the second power supply line (L2) on / off in accordance with the temperature of the cooking chamber 41, the cooking chamber 41 The cooking temperature sensor TCO2 is connected to prevent overheating.

The heater 8 is connected between the first power line L1 and the second power line L2 in front of the noise filter 1. In addition, a heater relay RY1 for turning on / off the heater 8 and a heater temperature sensor TCO3 for preventing overheating of the heater 8 are connected in series with the heater 8.

In addition, between the first power line L1 and the second power line L2 at the rear end of the noise filter 1, the lamp 2, the fan motor 3, the driving motor 4 and the low voltage transformer LVT are provided. In addition, the main relay RY4 for turning on / off the lamp 2, the fan motor 3, and the driving motor 4 is connected. Here, the lamp 2 and the fan motor 3 are driven by a power supply voltage (AC 230V), the drive motor 4 is a low voltage (AC 21 ~ 24V) drawn from one side of the fan motor (3) coil Driven.

In addition, the low voltage transformer LVT step-downs a power supply voltage and supplies a DC voltage to the PCB substrate 6 through a rectification means (not shown). The PCB 6 includes the microcomputer 9 shown in FIG. In addition, a plurality of circuit elements driven by the DC voltage are disposed.

In addition, the heater relay RY1 and the main relay RY4 together with each coil constitute a respective relay element, and each relay coil disposed on the PCB substrate 6 and controlled by the microcomputer 9. Is turned on / off.

In addition, the other side of the monitor switch (SW _MT ), one side of which is connected to the primary coil (7a) of the high-voltage transformer (HVT), one side of the low-voltage transformer (LVT) and the monitor fuse (FUSE2) through the cooking temperature sensor ( TCO2). The monitor fuse FUSE2 is disposed on the PCB substrate 6, and a second door switch SW2 is provided on the PCB substrate 6, which is turned on / off according to the opening / closing state of the door 43. Since the second door switch SW2 is configured to transmit the open / closed state of the door 43 to the microcomputer 9, the detailed description thereof will be omitted.

However, the main feature of the present invention, while controlling the application state of the power supply voltage between the input side power line (L2) connected to the cooking chamber temperature sensor (TCO2) and the primary coil (7c) of the high-voltage transformer (HVT) It interposes the integrated relay 100 which prevents an electric current. The integrated relay (100) is; Drive means 120 driven by the control of the microcomputer 9; And on / off by driving of the driving means 120 to provide a power supply voltage to the high-voltage driving unit 30, the lamp 2, the fan motor 3, and the driving motor 4, and the switch-on-operating terminal ( a) (b) is composed of an inrush current prevention relay switch RY10 which is first connected to the first terminal c connected to the PTC thermistor PTC at one end thereof and connected to the second terminal d after a predetermined time. .

4 to 6 show the relay switch structure of the present invention including the PTC thermistor and its operation state in detail. Here, a PTC thermistor (Positive Temperature Coefficient thermistor) refers to a static thermistor whose resistance value increases remarkably when the temperature rises, unlike a general negative characteristic thermistor.

As illustrated, the inrush current preventing relay switch RY10 has a fixed end connected to an output terminal A via the PTC thermistor PTC and a first fixing piece having the first terminal c formed at the other end thereof. (113); A second fixing piece (114) having a fixed end connected to the output terminal (A) and having the second terminal (d) having a predetermined distance from the first terminal (c) at the other end; And a movable terminal (a) formed at a fixed end and sequentially connected to the first terminal (c) and the second terminal (d) by the driving force of the driving means (20) at the other end. (b) is formed of the movable piece 115 formed.

In addition, the driving means 120 includes a relay coil 123 for generating a magnetic force by the current is conducted by the microcomputer (9); And a pressing member 122 driven about the hinge portion 121 by the magnetic force of the relay coil 123.

Referring to the operation of the present invention configured as described in detail as follows. When food is placed in the cooking chamber 41 and the door 43 is closed, the first door switch SW1, the second door switch SW2, and the monitor switch SW _MT are turned on so that the microwave oven is operable. do. In this state, when the user presses the operation key 21 to perform the microwave cooking function, the microcomputer 9 passes through the main relay RY4 and the integrated relay according to the present invention through respective coils on the PCB board 6. The inrush current prevention relay switch RY10 of 100 is turned on.

Therefore, since the contact point of the main relay RY4 is turned on, the lamp 2, the fan motor 3, and the drive motor 4 of the microwave oven are operated. In addition, the inrush current preventing relay switch RY10 normally consumes the inrush current generated by the high back electromotive force generated by the primary coil 7a of the high voltage transformer HVT immediately after the initial power is applied by the PTC thermistor PTC. Let the stove run.

In more detail, the input terminal B of the movable piece 115 of the inrush current prevention relay switch RY10 is connected to the power supply line L2 and the input side, and the first fixing piece 113 and the second side are connected. The output terminal A of the fixing piece 114 is connected to the power supply line L2 on the side of the high voltage transformer HVT primary coil 7a.

Here, the first terminal (c) of the first fixing piece 113 and the second terminal (d) of the second fixing piece (114) are respectively different from the movable terminals (a) (b) of the movable piece (115). The distance is maintained, and more specifically, the second terminal (d) from the movable terminal (a) (b) is located about 2 ~ 4mm farther than the first terminal (c).

Accordingly, when a current is conducted to the relay coil 123 of the driving means 120 by the microcomputer 9, a magnetic force is generated in the relay coil 123, and the pressing member 122 is closed by the magnetic force. It is driven around the branch 121. Accordingly, the movable piece 115 is moved toward the first and second fixing pieces 113 and 114 so that the movable terminals a and b are connected to the first terminal c and the second terminal d. Are connected sequentially.

Therefore, a predetermined time after the high back electromotive force inrush current generated in the primary coil 7a of the high voltage transformer HVT is consumed through the PTC thermistor PTC of one side of the first terminal c immediately after the initial power is applied, for example, As the second terminal (d) is connected after the delay process of 20 ~ 40㎳ as well as it can prevent the overload and damage of the microwave oven in advance.

Subsequently, when the normal driving power is supplied to the microwave oven as described above, the lamp 2, the fan motor 3, and the driving motor 4 are operated as described above, and in the high voltage transformer HVT, A high voltage is generated, and this high voltage is supplied to the magnetron (MGT) via the high voltage capacitor (HVC) and the high voltage diode (HVD). Therefore, since the magnetron MTG is driven to emit microwaves, it is possible to cook food in the cooking chamber 41.

Therefore, according to the relay device for preventing inrush current of a microwave oven according to the present invention, instead of installing a plurality of expensive relays in the related art, an integrated relay including an inrush current prevention relay switch in which a power relay and an inrush relay are integrated is mounted in a microwave oven. Therefore, the inrush current of the microwave is effectively blocked, and the workability is improved and the manufacturing cost is reduced by eliminating the wiring process.

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 are intended to fall within the scope of the claims set forth.

Claims (3)

According to the control of the microcomputer provided on the PCB substrate to form an integrated relay for controlling the application state of the power supply voltage in the microwave driven by the high-voltage drive unit, lamp, fan motor and drive motor, the integrated relay; Drive means driven by a magnetic force generated by the control of the microcomputer; And On / off by driving of the drive means to provide a power supply voltage to the high-voltage drive unit, lamp, fan motor and drive motor, when the switch is on, the movable terminal is first connected to the first terminal connected to the PTC thermistor at one end thereof, Inrush current prevention relay device of the microwave oven, characterized in that the inrush current prevention relay switch is connected to the second terminal after a time. The relay switch of claim 1, wherein the inrush current prevention relay switch A first fixing piece having a fixed end connected to an output terminal via the PTC thermistor and having the first terminal at the other end; A second fixing piece having a fixed end connected to the output terminal and having the second terminal at a second end having a predetermined distance from the first terminal; And An input terminal is formed at a fixed end, and the other end is configured to include a movable piece having the movable terminal sequentially connected to the first terminal and the second terminal by a driving force of the driving means. Current prevention relay device. The method of claim 1, wherein the driving means A relay coil in which current is conducted by the micom to generate a magnetic force; And Inrush current prevention relay device of the microwave oven, characterized in that consisting of a pressing member driven around the hinge portion by the magnetic force of the relay coil.