JP3501140B2 - Cooling device for power supply for magnetron drive - Google Patents

Description

Description: 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 device such as a microwave oven for performing dielectric heating using a magnetron. It is. 2. Description of the Related Art A power supply for driving a magnetron, called a so-called inverter circuit, 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. A voltage from a commercial power supply is converted to 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 electric power is converted into a high frequency high voltage by the leakage transformer 1. 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 filament of a magnetron 9 is connected to a high-voltage lead wire 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 radiation fins 2 with 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 radiating fins are composed 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 heat radiating fins 2 with heat conductive silicon grease or the like therebetween and transmits heat to the heat radiating fins 2. When the fins of the radiating fins 2 are well blown by the wind, it is not necessary to use a very low loss and expensive power switching element 14. Power supply 12 for magnetron drive
Even in this case, it is completed in this form, and it is not necessary to stock many models according to the type of the set, and it is possible to realize very unified and efficient manufacturing. In a magnetron drive power supply using this inverter circuit, each component is generally cooled by forced cooling by 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 an orifice of a cooling fan. An air guide 21 guides the air 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 biggest problem is to cool the radiation fins 2 connected to the leakage transformer 1 and the power switching element 14, which are the most severe in 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 air from the cooling fan becomes radial and is in the direction of A.
Therefore, the wind A from the cooling fan first strikes the 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 that of the initial wind A flowing out of the cooling fan. Further, 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 power is weaker than the wind A which emerges radially. Therefore, it cannot be said that the cooling configuration completely utilizes the wind of the cooling fan, but it has the advantage of a simple cooling configuration and has been used conventionally. [0008] However, in recent years,
The demand for an output UP of a microwave oven has become stronger, and accordingly, the power consumption of a power supply for driving a magnetron, particularly the power consumption of a switching element and a leakage transformer, has been significantly increased. Accordingly, 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. 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 comprises: a power switching element such as an IGBT; ON / OF at high speed
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 unit for controlling the parts, and leakage transformer for boosting a high frequency AC voltage, and a high pressure rectifying means for applying a high DC voltage to a magnetron connected to the secondary winding of said leakage transformer, at least before Symbol inverter section, the inverter control unit, said leakage transformer, said high pressure rectifying means, a magnetron drive power supply of mounting the radiating fins to the PCB, a cooling fan for forcibly cooling the magnetron driving power source, the wind from the cooling fan Equipped with an air guide leading to the magnetron drive power supply , Aims to space saving of the cooling mechanism,
The air from the cooling fan is efficiently
Guided to the power supply for driving Gnetron to improve cooling efficiency
Air guide wall, radiation fins and leakage
As the lance is approached, the axial direction of the cooling fan intersects the printed circuit board of the magnetron driving power supply at an acute angle, and one end of the opening of the air guide is connected to the cooling fan .
The cooling air is easy to flow along the wall by fitting . 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. DETAILED DESCRIPTION OF THE INVENTION 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 by the power switching element, and converting the power into a high-frequency AC voltage. 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 for applying a high-voltage DC voltage to a magnetron connected to a secondary winding of the leakage transformer ;
Before Symbol inverter even without, the inverter control unit, said leakage transformer, said high pressure rectifying means, a magnetron drive power supply of mounting the radiating fins to the PCB, a cooling fan for forcibly cooling the magnetron drive power supply, the wind from the cooling fan; and a air guide for guiding the magnetron drive power supply, space saving of the cooling mechanism
Air from the cooling fan efficiently.
To the magnetron drive power supply via the
In order to raise the air guide wall and the radiation fin and front
As the leakage transformer is brought closer, the axial direction of the cooling fan intersects the printed circuit board of the magnetron driving power supply at an acute angle, and one end of the opening of the air guide is fitted to the cooling fan , so that the cooling air flows to the wall. Flow along
With the easy configuration, the wind from the cooling fan
The power can be efficiently applied to the magnetron driving power supply via the air guide, and the cooling efficiency can be increased.
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. 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 magnetron driving power source, 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, and two openings of the air guide are provided in the horizontal direction with the paper phenol board 17. The air 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 magnetron drive power supply according to 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 surface of the air guide as shown in FIG. 2A, so that the wind speed does not decrease due to the air guide wall as in the related art. . Therefore, the wind speed of the wind flowing along this wall surface can be secured strongly. 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 the relationship between the wind speed of the wind A and the wind speed of the wind A. 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 part 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 this 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, and thereby the temperature of the power switching element 14 can be reduced. It can be seen that the greater 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 the leakage transformer, it 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 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. 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 for a magnetron driving power supply according to an embodiment of the present invention. FIG. 2 is a view showing a wind direction of the cooling device for the magnetron driving power supply. Characteristic diagram of the inclination and wind speed of the cooling fan of the cooling device of the drive power supply [Fig. 4] Characteristic diagram of the wind speed and temperature rise of the cooling fan of the cooling device of the magnetron drive power supply [Fig. FIG. 6 is a front view and a side view of a conventional magnetron driving power supply. FIG. 7 is a block diagram showing a configuration of the magnetron driving power supply. FIG. 8 is a cooling of the conventional magnetron driving power supply. Configuration diagram [FIG. 9] Cooling configuration diagram of conventional magnetron driving power supply (in case of air guide transmission) [FIG. 10] Wind direction indication diagram in conventional cooling configuration of magnetron driving power supply [Explanation of reference numerals] Cage transformer 2 radiation fins 12 magnetron drive power supply 14 power switching element 18 cooling fan 21 air guide

Continuation of the front page (56) References JP-A-5-190276 (JP, A) JP-A-8-339887 (JP, A) JP-A 2002-243169 (JP, A) JP-A-62-229683 (JP, A) A) JP-A-2001-15258 (JP, A) JP-A-8-284831 (JP, A) JP-A-4-70907 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05B 6/64 F24C 7/02

Claims (1)

(57) [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, A radiation fin for dissipating a loss generated by tightly fastening the switching element 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, a high pressure rectifying means for applying a high DC voltage to a magnetron connected to the secondary winding of the leakage transformer, at least before Symbol inverter unit, the inverter control unit, said leakage transformer, said high pressure rectifying means, the heat radiating fin print A power supply for driving the magnetron mounted on the substrate, and a power supply for driving the magnetron. A cooling fan for forcibly cooling the source, the wind from the cooling fan; and a air guide for guiding the magnetron drive power supply, achieving space saving of the cooling mechanism, from the cooling fan
For driving the magnetron efficiently through the air guide
The air guide wall to guide power supply and increase cooling efficiency
And the radiation fins and the leakage transformer
At the same time, the axial direction of the cooling fan intersects the printed circuit board of the power supply for magnetron driving at an acute angle, and one end of an opening of the air guide is fitted to the cooling fan to form the cooling fan.
A cooling device for the power supply for driving the magnetron, which is configured so that the wind can easily flow along the wall .