JP2606987Y2 - Transistor inverter device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transistor inverter device for inductively heating a workpiece by, for example, a high-frequency current, and more particularly to a transistor mounting structure when a plurality of transistors are connected in parallel.

[0002]

2. Description of the Related Art Conventionally, a transistor inverter device used for high-frequency induction heating or the like is disclosed, for example, in Japanese Utility Model Laid-Open No. Hei 5-3368.
An apparatus disclosed in Japanese Patent Application Laid-Open No. 7-107 is known. In this inverter device, a transistor is fixed to a wall surface of a case via a heat sink, and a printed circuit board on which electronic components are mounted is arranged below the transistor.

[0003]

However, in the above-described inverter device, there is a problem that the printed circuit board is adversely affected by dew condensation generated on the heat radiating plate and malfunctions. That is, in the case of induction heating with a high-frequency large current, the current flowing through the transistor also becomes a large current, and when this current is turned on and off, condensation occurs on the heat radiation plate when used for a long time. And this dew falls on the printed circuit board arranged below the transistor,
Insulation between patterns and between terminals of electronic components deteriorates, and a circuit formed on the substrate malfunctions.

[0004] The present invention has been made in view of the above-described circumstances, and its purpose is to reduce the occurrence of dew condensation on the heat sink.
An object of the present invention is to provide a transistor inverter device capable of reliably preventing adverse effects on a printed circuit board, achieving stable operation for a long period of time, and easily performing assembly and maintenance.

[0005]

In order to achieve the above object, a transistor inverter device according to the first aspect of the present invention has a plurality of transistors arranged substantially vertically .
A pair of heat sinks for simultaneously pressing and holding surfaces substantially parallel to the vertical direction, and being integrated by being assembled on the upper part of the heat sink, are disposed substantially vertically above the heat sink, and electronic components are mounted. A printed circuit board, the terminals of the transistors being directed upward, soldered and fixed to the pattern of the printed circuit board, a plurality of transistors are connected in parallel, and a side opposite to the transistor press-contact surface of the heat sink. Characterized in that a cooling pipe is fixed to the surface.

[0006]

According to the transistor inverter device of the first aspect, a printed circuit board on which electronic components are mounted is integrated with a pair of heat sinks to which a plurality of transistors in a substantially vertical state are fixed. The transistors in the substantially vertical state are arranged with their terminals facing upward. For example, two terminals are connected in parallel by being soldered and fixed to a substrate pattern. The heat generated from the transistor is radiated by a radiator plate cooled by a cooling pipe. And, when dew condensation occurs on the heat sink, the dew drops downward, the adverse effect on the printed circuit board due to the dew condensation is surely prevented, and the heat sink and the printed circuit board are integrally assembled and unitized, It is easy to assemble and maintain the device.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a circuit diagram of a transistor inverter device according to the present invention. In the figure, an inverter device 1 is connected to a pair of FET units 8 and 9 including FETs 2 and 3 and resistors 4 to 7, a bias circuit 10 for driving the FETs 2 and 3, and output sides of the FET units 8 and 9. It has a coil 11, an output transformer 12, and the like.

The FET units 8 and 9 have the same configuration. Hereinafter, the FET unit 8 will be described with reference to FIGS. As shown in FIG. 2, the FET unit 8 includes eight FETs 2a to 2h and the FETs 2a to 2h.
Resistances 4a to 4h connected to respective sources of
And eight resistors 5a-5 connected to each gate, respectively.
h, which are connected in parallel. The FETs 2a-2h and the resistors 4a-4h, 5a-5
h is assembled as shown in FIGS.

That is, the FETs 2a to 2h are connected to a pair of heat sinks 1
A screw 15 is pressed and held between the terminals 3 and 14, and the three terminals are disposed so as to face upward. A printed circuit board 17 is vertically fixed on an upper portion of the heat radiating plate 13 via a mounting plate 16, and the tips of the sources and gates of the FETs 2 a to 2 h are attached to patterns 17 a and 17 b formed on the lower portion of the printed circuit board 17. Each part is soldered. The drains of the FETs 2a to 2h are fixed to the heat sink 14 by screws 18 (see FIG. 4). On the front side of the printed circuit board 17, resistors 4a to 4h are provided and soldered to the patterns 17a and 17c. On the back side, resistors 5a to 5h are provided and soldered to the patterns 17b and 17d. .

Copper square pipes 21 and 22 are fixed to the radiator plates 13 and 14 in the longitudinal direction by brazing, respectively, and hose connectors 23a and
23b, 24a and 24b are respectively fixed by brazing. Cooling water is circulated and supplied to the square pipes 21 and 22 from a cooling water supply device (not shown).
Temperature rise is suppressed. Further, the mounting column 25 is fixed to the heat radiating plate 13, whereby the mounting column 25, the heat radiating plates 13 and 14, the FETs 2 a to 2 h, the printed board 17 and the like are integrally assembled to form the FET unit 8. Then, as shown in FIG. 4, by fixing the mounting support 25 of the FET unit 8 to the bottom plate 26 of the inverter device 1, the printed circuit board 17 is vertically disposed on the heat radiating plates 13 and 14.

The FET unit 9 is constructed in exactly the same manner as the FET unit 8, and is fixed to the bottom plate 26 at a position symmetrical to the FET unit 8, for example. The FETs 2a to 2h
Are increased or decreased according to the power required by the inverter device 1, and the number of the heat sinks 1
The sizes of 3, 14, the printed circuit board 17 and the like are also set.
The terminals 27 (pattern 17) of the FET units 8 and 9
c) is grounded, the terminal 28 (radiator plate 13) is connected to the middle part of the coil 9, and the terminal 29 (pattern 17a) is
Connected to capacitors 36 and 37 described later.

As shown in FIG. 1, a choke coil 31 is connected to an intermediate tap of the coil 11, and a primary side of an output transformer 12 is connected to both ends thereof. A heating coil 32 is connected to the secondary side of the output transformer 12, and a capacitor 33 is connected in parallel to the primary side. The primary side of the output transformer 12 has its both ends grounded via capacitors 34 and 36 and capacitors 35 and 37 connected in series, respectively, and its intermediate tap is grounded via a capacitor 38.

The connection point between the capacitors 34 and 36 is an FET
The terminals 29 of the unit 8 are connected to the capacitors 35 and 37.
Are connected to the terminals 29 of the FET unit 9, respectively. These terminals 29 are connected to the bias circuit 10
Connected to each other. The bias circuit 10 includes a smoothing capacitor 40 connected between DC power supplies, and a pair of resistors 41 and 42 and resistors 43 and 44 connected in series. The connection point between the resistors 41 and 42 is connected to the terminal 29 of the FET unit 8, and the connection point between the resistors 43 and 44 is connected to the terminal 29 of the FET unit 9.

Next, the operation of the inverter device will be described. First, the FETs 2 and 3 of the FET units 8 and 9
Suppose, for example, a bias is supplied from the bias circuit 10 and, for example, the FET 2 is turned on. When the FET 2 is turned on, the current stored in the choke coil 31 is supplied to the coil 11 via the intermediate tap. By supplying this current, a high voltage is generated at both ends of the coil 11,
The parallel resonance circuit composed of the output transformer 12 and the capacitor 33 resonates, and the signal is supplied to the gate of the FET3 to turn on the FET3 and turn off the FET2. Then, the on and off of the FETs 2 and 3 are alternately repeated, and a sine waveform of a predetermined frequency, that is, a high-frequency current is output to the secondary side of the output transformer 12. With this current, the work 45 arranged at the tip of the heating coil 32 (see FIG. 1)
Is induction-heated, for example, brazing or quenching is performed.

As described above, according to the above embodiment, the FET
2, 3 with a heat sink 13, so that its terminals are directed upward.
14 and a printed circuit board 17
, The use of the inverter device 1
Even if dew condensation occurs on the heat radiating plates 13 and 14, the dew condensation has no effect on the printed circuit board 17 and does not malfunction even after long-term use. In addition, heat sinks 13 and 14
Since the square pipes 21 and 22 through which the cooling water flows are fixed, the temperature rise of the square pipes 21 and 22 is suppressed, and the thermal runaway and dew condensation of the FETs 2 and 3 can be suppressed.

Further, the printed circuit board 17 is provided with the heat radiating plate 1.
Since it is disposed vertically above the upper and lower sides 3 and 14, it is less affected by the heat generated from the heat radiating plates 13 and 14, and the deterioration of the printed board 17 and the resistors 4 to 7 can be prevented. it can. In addition, FET2,3, heat sink 13,
14. Since the printed circuit board 17 is integrally assembled into a unit, maintenance work such as assembling to the inverter device 1 and replacing the FETs 2 and 3 can be easily performed.

In the above embodiment, the case where the FET is used as the transistor has been described. However, the present invention can be applied to all transistors fixed to the heat sink, such as a power transistor, MOSFET, SIT, and transistor module. Further, in the above embodiment, the printed circuit board is arranged vertically above the heat sink, but for example, the printed circuit board may be arranged horizontally above the heat sink.
Furthermore, the shapes of the heat radiating plate and the printed circuit board, the mounting structure of the printed circuit board to the heat radiating plate, and the like in the above embodiment are merely examples, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

[0018]

As described above in detail, according to the transistor inverter device of the present invention, the printed circuit board on which the electronic components are mounted is assembled and integrated above the heat radiating plate which presses and holds the substantially vertical transistor. Therefore, even if dew condensation occurs on the heat sink, the adverse effect on the printed circuit board is reliably prevented, stable operation is obtained for a long time, and the transistor, the heat sink and the printed circuit board are united. It is advantageous in that the unit can be easily attached to the device and maintenance can be easily performed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a transistor inverter device according to the present invention.

FIG. 2 is a circuit diagram of the FET unit.

FIG. 3 is a perspective view of the unit.

FIG. 4 is a sectional view of the unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inverter device 2, 3, 2a-2h FET 8, 9 FET unit 13, 14 Heat sink 17 Printed circuit board 17a-17d Pattern 21, 22 Square pipe

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-364379 (JP, A) JP-A 4-124806 (JP, U) JP-A-63-143093 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) H02M 7/48

Claims (1)

(57) [Scope of request for utility model registration] 1. A pair of radiating plates for simultaneously pressing and holding substantially parallel surfaces of a plurality of transistors arranged in a substantially vertical direction in parallel with a substantially vertical direction, and a radiating plate integrated by being assembled on an upper portion of the radiating plate. And a printed circuit board on which electronic components are mounted in a substantially vertical state above, and the terminals of the transistor are directed upward to be soldered and fixed to a pattern of the printed circuit board. Are connected in parallel, and a cooling pipe is fixed to a surface of the heat sink opposite to the transistor press-contact surface.