JP2002313552A - Cooling device for magnetron drive power source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve cooling performance in a cooling device for a magnetron drive power source. SOLUTION: This cooling device is provided with the magnetron drive power source 12, a cooling fan 18 and an air guide 21. The cooling fan 18 is inclined with respect to the horizontal direction of the magnetron drive power source 12 and fitted to the air guide 21. The cooling performance of the magnetron drive power source is thereby improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The technical field of the present invention relates to a cooling structure of a power supply for driving a magnetron of a high-frequency heating apparatus for performing dielectric heating using a magnetron such as a microwave oven.

[0002]

2. Description of the Related Art A so-called inverter circuit power supply in which a high voltage circuit, a low voltage circuit, and a leakage transformer are integrated on a printed circuit board is widely used as a power supply for a microwave oven. FIG. 6 is a front view and a side view of a conventional magnetron driving power supply. As described above, the components are integrally mounted on a single board to form a single unit board. 1 is a leakage transformer, 2
Are radiating fins for cooling the power switching element. FIG. 7 is a block diagram of the inverter circuit.

[0003] A voltage from a commercial power supply is converted into a unidirectional voltage by a unidirectional power supply unit 3 composed of a diode bridge. The unidirectional voltage is subjected to current smoothing and voltage smoothing by a rectifying filter 6 including a choke coil 4 and a smoothing capacitor 5. The output of the rectifying filter 6 is converted by the inverter unit 7 into high-frequency power of 30 to 50 KHz. Various methods such as a voltage resonance type, a current resonance type, a partial resonance type, and a half bridge type are applied to the inverter unit. The power is converted by the leakage transformer 1 into a high frequency high voltage. This high-frequency voltage is converted into a high-voltage DC voltage by high-voltage rectification means 8 composed of a capacitor and a diode.

The leakage transformer 1 has a third winding, and a high voltage lead 10
Through the cathode to emit electrons from the cathode. On the other hand, the voltage converted into the high-voltage DC voltage by the high-voltage rectification means 8 is also applied between the anode and the cathode of the magnetron 9 through the high-voltage lead wire 10 to radiate the microwave output into the oven, and heat the food by dielectric heating. . The inverter unit 7 includes an inverter control unit 11
And the power switching element in the inverter unit 7 is ON / OFF controlled. With the above configuration, the magnetron driving power supply 12 is configured. By the way, 13 is dropped to the chassis and becomes the ground potential.

FIG. 6 shows a power supply 12 for driving the magnetron.
The power switching element 14 is fastened to the radiating fins 2 by screws and is closely attached thereto. This power switching element 14
Is transmitted to the radiation fins 2 as heat, and the radiation fins 2 are cooled by the forced cooling air. Reference numeral 15 denotes a high-voltage capacitor, and 16 denotes a high-voltage diode, which constitutes the high-voltage rectifier 8. All of these components are mounted on a paper phenol board 17 to constitute the integrated magnetron drive power supply 12 described with reference to FIG. Since the present inverter system assumes a two-transistor system, it has two power switching elements 14.

The heat radiation fins are composed of a group of fins protruding laterally from a core portion in a direction parallel to the transistor, and are cooled by passing air therethrough. The power switching element 14 is fastened to the radiating fins 2 with heat conductive silicon grease or the like therebetween and transmits heat to the radiating fins 2. When the fins of the radiating fins 2 are well hit by the wind, it is not necessary to use a power switching element 14 having such a low loss and high cost. Power supply 12 for magnetron drive
Even in this case, it becomes a completed state, and it is possible to realize a very unified and efficient manufacturing without having to prepare many models according to the type of set.

In a magnetron drive power supply using this inverter circuit, each component is generally cooled by forced cooling with a cooling fan. FIG. 8 is a cooling configuration diagram of a conventional magnetron driving power supply. Reference numeral 18 denotes a cooling fan which is operated by a motor 19. 20
Indicates the orifice of the cooling fan. An air guide 21 guides the wind from the cooling fan to the power supply 12 for driving the magnetron. The air from the cooling fan is concentrated by the air guide 21 and strikes the power supply 12 for driving the magnetron. FIG. 9 is a cooling configuration diagram when the light passes through the air guide 21. The greatest challenge is to cool the radiation fins 2 connected to the leakage transformer 1 and the power switching element 14, which have the highest temperature. FIG. 10 shows the flow of wind in a conventional cooling configuration. When a propeller fan is used as a cooling fan, the flow of wind from the cooling fan becomes radial and is in the direction of A.
Therefore, the wind A from the cooling fan first strikes a part 21-P of the air guide, and thereafter flows in the direction of A 'in the figure. Therefore, the wind speed of A 'is considerably lower than the initial wind A flowing out of the cooling fan. The wind B parallel to the axial direction of the direct cooling fan directly hits the power supply for driving the magnetron, but the wind is weaker than the wind A which emerges radially. Therefore, although it cannot be said that the cooling configuration completely utilizes the wind of the cooling fan, it has an advantage of a simple cooling configuration and has been used conventionally.

[0008]

However, in recent years,
The demand for the output UP of the microwave oven has become stronger, and accordingly, the power consumption of the power supply for driving the magnetron, particularly the power consumption of the switching element and the leakage transformer, has been significantly increased. Therefore, it has become necessary to design a more efficient cooling configuration of the power supply for driving the magnetron. In addition, due to the miniaturization of microwave ovens and the adaptation to novel designs, the space in the machine room, such as cooling devices and power supplies for driving magnetrons, has become severely restricted, and an efficient cooling configuration in a limited space has become necessary. Was.

An object of the present invention is to solve the above-mentioned conventional problems and to provide an efficient cooling configuration in a limited space.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned conventional problems, a cooling device for a power supply for driving a magnetron according to the present invention uses a power switching element such as an IGBT and a commercial power supply at high speed by the power semiconductor element. ON / OF
An inverter for converting the power switching element into a high-frequency AC voltage; a radiating fin formed by an extruded aluminum molding method for dissipating a loss generated by tightly fastening the power switching element and cooling the power switching element; An inverter control section for controlling the section, a leakage transformer for boosting a high-frequency AC voltage, high-voltage rectifying means for applying a high-voltage DC voltage to a magnetron connected to a secondary winding of the leakage transformer, and the power switching element. A power supply for driving a magnetron for mounting the radiating fins, the inverter unit, the inverter control unit, the leakage transformer, the high-voltage rectifier, and the radiating fins on a single printed circuit board; and forcibly cooling the magnetron driving power supply. Cooling fan, and wind from the cooling fan An air guide for guiding the power supply to the magnetron drive, wherein the axial direction of the cooling fan intersects the printed circuit board of the power supply for magnetron at an acute angle, and one end of the opening of the air guide and the cooling fan are fitted. It is configured.

Thus, the air from the cooling fan can be efficiently applied to the power supply for driving the magnetron via the air guide, thereby increasing the cooling efficiency.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 is an IGBT.
A power switching element comprising: a power supply element, an inverter section for turning on / off the commercial power supply at a high speed and converting it into a high-frequency AC voltage, and a loss caused by tightly connecting the power switching element to the power switching element. A radiation fin that cools the power switching element, an inverter control unit that controls the inverter unit, and a leakage transformer that boosts a high-frequency AC voltage,
A high-voltage rectifier that applies a high-voltage DC voltage to a magnetron connected to a secondary winding of the leakage transformer, the heat-dissipating fin on which the power switching element is mounted, the inverter unit, the inverter control unit, the leakage transformer, A power supply for driving the magnetron that mounts the high-voltage rectifier and the radiating fins on a single printed circuit board; a cooling fan that forcibly cools the power supply for driving the magnetron; and air that guides wind from the cooling fan to the power supply for driving the magnetron. A guide is provided, and the axial direction of the cooling fan intersects with the printed circuit board of the magnetron driving power supply at an acute angle, and the cooling fan is fitted with one end of the opening of the air guide to cool the cooling fan. The air from the fan is efficiently applied to the magnetron drive power supply via the air guide. Cooling efficiency can be improved. Further, the cooling fan can be fitted to the air guide and arranged near the power supply for driving the magnetron, so that the space for the cooling mechanism can be saved.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a cooling configuration of a power supply for driving a magnetron according to the present invention. The cooling fan 18 is disposed at a position where its axial direction S intersects the horizontal direction of the power supply for magnetron driving, that is, the paper phenol board 17 at an acute angle (angle Φ), and fits into the opening at one end of the air guide 21. It has a configuration. The air guide 21 is configured to surround the magnetron driving power supply 12 from the longitudinal direction and the upper part thereof, and two openings of the air guide are provided in the horizontal direction with the paper phenol board 17. The wind from the cooling fan enters the magnetron driving power supply through one opening of the air guide 21 fitted with the cooling fan, flows through the magnetron driving power supply, and exits through the other opening of the air guide 21. I'm going to go.

FIG. 2 shows the flow of air from the cooling fan in the cooling configuration of the power supply for driving the magnetron of the present invention. Here, the size L of the opening of the air guide on the side fitted to the cooling fan is set slightly larger than the diameter F of the cooling fan. Generally, a propeller fan is used as a cooling fan. In that case, the flow of the wind coming out of the cooling fan is radial, but as described above, by considering the size and the axial direction of the opening of the air guide,
Radial wind from the cooling fan flows in parallel along the wall of the air guide as shown in FIG. 2A, so that a decrease in wind speed due to the wall of the air guide does not occur as in the related art. . Therefore, a strong wind speed of the wind flowing along the wall surface can be secured. This wind flows in the magnetron drive power supply almost in parallel.

FIG. 3 shows the intersection angle Φ between the axial direction S of the cooling fan and the phenol substrate 17 of the power supply 12 for driving the magnetron.
6 is a graph showing a relationship between the wind speed of a wind A and the wind speed. When the intersection angle Φ is small, that is, when the cooling fan is perpendicular to the phenol substrate of the magnetron driving power supply, the wind from the fan first hits the upper part of the air guide 21 and the wind speed is weakened. When the crossing angle Φ is large, that is, when the cooling fan is parallel to the phenol substrate of the power supply for driving the magnetron, the wind does not flow to the upper portion of the air guide, and the wind speed is reduced. The angle at which the wind speed can be increased most is around 45 ° (D). By optimizing the intersection angle, the most efficient cooling configuration can be realized.

FIG. 4 is a graph showing the wind speed A and the temperature of the power switching element 14. As the wind speed A increases, the amount of air passing through the radiating fins 2 connected to the power switching element 14 increases, so that the temperature of the radiating fins can be reduced, whereby the temperature of the power switching element 14 can be reduced. It can be seen that the higher the wind speed A, the lower the temperature and the greater the cooling effect. The same can be considered for the temperature characteristics of the leakage transformer. In a leakage transformer, this is how much wind can be applied to the winding on the surface.

FIG. 5 shows the flow of the wind in the power supply for driving the magnetron, and it is possible to flow a strong wind at the hatched portions of the radiation fin 2 and the leakage transformer 1. As a result, the temperatures of the power switching element 14 and the leakage transformer 1 can be reduced. Considering the property that the wind easily flows along the wall, the air guide wall and the radiator fins 2 and leakage transformer 1
The closer the distance, the greater the cooling effect.

As described above, the cooling fan is arranged so that the crossing angle Φ between the axial direction of the cooling fan and the phenol substrate 17 of the magnetron driving power supply 12 is an optimum angle, and the cooling fan and one end of the air guide are fitted together. With the configuration, it is possible to efficiently guide the wind from the cooling fan to the power supply for driving the magnetron, and the cooling efficiency of the power supply for driving the magnetron is significantly improved.

[0020]

As described above, according to the present invention, the air from the cooling fan can be efficiently guided to the power supply for driving the magnetron via the air guide, and the cooling efficiency can be improved. Further, the cooling fan can be fitted to the air guide and arranged near the power supply for driving the magnetron, so that the space for the cooling mechanism can be saved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a cooling device of a power supply for driving a magnetron according to an embodiment of the present invention.

FIG. 2 is a view showing a wind direction of a cooling device of the power supply for driving the magnetron.

FIG. 3 is a characteristic diagram of inclination and wind speed of a cooling fan of a cooling device for the magnetron driving power supply.

FIG. 4 is a characteristic diagram of wind speed and temperature rise of a cooling fan of a cooling device for the magnetron driving power supply.

FIG. 5 is a sectional view of a main part showing a flow of wind in a power supply for driving a magnetron

FIG. 6 is a front view and a side view of a conventional magnetron driving power supply.

FIG. 7 is a block diagram illustrating a configuration of a power supply for driving a magnetron.

FIG. 8 is a diagram showing a cooling configuration of a conventional magnetron driving power supply.

FIG. 9 is a diagram showing a cooling configuration of a conventional magnetron drive power supply (in the case of air guide transmission).

FIG. 10 is a view showing a wind direction in a conventional cooling configuration of a power supply for driving a magnetron.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Leakage transformer 2 Heat radiation fin 12 Magnetron drive power supply 14 Power switching element 18 Cooling fan 21 Air guide

Continued on the front page F-term (reference) 3K090 AA02 BA01 EB20 EB23 EB25 3L086 AA01 BE11 DA17

Claims (1)

[Claims] 1. A power switching element such as an IGBT, an inverter unit for turning on / off a commercial power supply at a high speed by the power switching element and converting it into a high-frequency AC voltage, and tightly fastened to the power switching element. A radiation fin for dispersing the generated loss and cooling the power switching element, an inverter control section for controlling the inverter section, a leakage transformer for boosting a high-frequency AC voltage, and a secondary winding of the leakage transformer. High-voltage rectification means for applying a high-voltage DC voltage to the magnetron to be performed, the radiator fin having the power switching element mounted thereon, the inverter unit, the inverter control unit, the leakage transformer, the high-voltage rectifier, and the radiator fin. Magnetron drive electronics mounted on a single printed circuit board A cooling fan for forcibly cooling the magnetron driving power supply, and an air guide for guiding wind from the cooling fan to the magnetron driving power supply, wherein the axial direction of the cooling fan is a printed circuit board of the magnetron driving power supply. And a cooling fan for a magnetron driving power supply, wherein the cooling fan is fitted at one end of the opening of the air guide with a cooling fan.