JPH0593022U - Boost coil - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a booster coil that can significantly reduce the cost and size of the device itself. [Structure] A tap (31, 32, 33) is provided at an intermediate portion of a main coil 24 wound with a small-diameter pipe, and an auxiliary coil (25) is provided between the taps (31, 32, 33).
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Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a boost coil used in, for example, a high frequency heating device.

[0002]

[Prior Art]

 Conventionally, a high-frequency heating device used for brazing a cemented carbide tip to a base metal of a circular saw is disclosed in, for example, Japanese Patent Laid-Open No. 55-21803. In this heating device, the output of the DC-AC inverter circuit is boosted by a high voltage transformer to obtain a large amount of high frequency power.

[0003]

[Problems to be solved by the device]

 However, since this heating device uses a high-voltage transformer, the cost of the heating device increases, and when a large voltage (electric power) is required, the transformer becomes large and the device itself becomes large. There was a problem to do. The present invention aims to solve the above-mentioned problems, and provides a booster coil capable of significantly reducing the cost and downsizing the device itself.

[0004]

[Means for Solving the Problems]

 In order to achieve such an object, the boost coil of the present invention comprises a small diameter pipe wound around an intermediate tap to which a current source is connected, and at least two taps provided on both sides of the intermediate tap. And a main coil having the above, the intermediate tap, and an auxiliary coil wound between the taps on both sides.

[0005]

[Action]

 In the booster coil of the present invention, when current is supplied to the coil from the current source through the intermediate tap, a part of the current circulates through the auxiliary coil. Due to this circulation of current, the magnetic flux generated from the coil increases, and a high voltage is generated across the coil.

[0006]

【Example】

 An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a circuit diagram of a main part when the booster coil according to the present invention is used in a high frequency induction heating device. In the figure, in FETs 1 and 2 (including SIT) as a pair of switching elements, each source is grounded through resistors 3 and 4 (connected to the negative side of the DC power supply ... The same applies hereinafter), and each gate thereof. Resistors 5 and 6 are connected to each. Further, the drains are respectively connected to the intermediate portion of the booster coil 7, whereby the FETs 1 and 2 are push-pull connected. The step-up coil 7 has a choke coil 8 connected to its intermediate tap and a primary side of an output transformer 9 connected to both ends thereof. A heating coil 10 is connected to the secondary side of the output transformer 9, and a capacitor 11 is connected in parallel to the primary side thereof. The capacitor 11 and the primary coil 12 of the output transformer 9 form a parallel resonance circuit. The primary side of the output transformer 9 is grounded via the capacitors 13 and 15 and the capacitors 14 and 16 whose both ends are connected in series, and the intermediate tap thereof is grounded via the capacitor 17. As a result, the capacitors 13, 15, 17 and half of the primary coil 12 of the output transformer 9 (upper half in the figure), and the capacitors 14, 16, 17 and half of the primary coil 12 (see the figure) In the lower half of the above), the resonance circuits described later are respectively formed. The connection point (G2) of the capacitors 13 and 15 is connected to the input side of the resistor 6 connected to the gate of the FET2, and the connection point (G1) of the capacitors 14 and 16 is connected to the gate of the FET1. 5 are connected to the input side respectively. The resistors 5 and 6 are connected to the bias circuit 18. The bias circuit 18 is formed by a smoothing capacitor 19 connected between DC power sources, and a pair of resistors 20, 21 and resistors 22, 23 connected in series. The connection point of the resistors 22 and 23 is connected to the resistor 5, and the connection point of the resistors 20 and 21 is connected to the resistor 6.

As shown in FIG. 2, the boosting coil 7 is composed of a main coil 24 and an auxiliary coil 25 fitted in an intermediate portion of the main coil 24. The main coil 24 is formed by winding a copper pipe 26 having a diameter of, for example, 4 mm a plurality of times, and connecting couplers 27 and 28 for supplying and discharging cooling water to both ends thereof. Further, the taps 29 and 30 are fixed to both ends, and the three taps 31, 32 and 33 are fixed to the middle part. As a result, the main coil 24 is divided into four, and as shown in FIG. 4, the number of turns is set to 24a 2 = 24b, 24c = 24d. As shown in FIG. 3, the copper pipe 26 is fitted with an insulating tube 34 made of, for example, glass fiber or the like. On the other hand, similar to the main coil 24, the auxiliary coil 25 is formed by winding a copper pipe 35 having a diameter of, for example, 4 mm, connecting couplers 36 and 37 to both ends thereof, and fixing taps 38 and 39. A tap 40 is fixed to the intermediate portion of the auxiliary coil 25, and the number of turns of the tap 40 is set to 25a = 25b. The inner diameter of the auxiliary coil 25 is set larger than the outer diameter of the main coil 24. Then, the auxiliary coil 25 is moved as shown by the arrow A in FIG. 2 to be fitted on the outer side of the main coil 24, and the taps 38, 39 and 40 are attached to the taps 31, 32 and 33, and bolts and nuts (not shown). Etc., and fix each with electrical connection. As a result, the booster coil 7 of the circuit diagram shown in FIG. 4 is formed. Cooling water is supplied to the couplers 27 and 36 from a cooling water supply device (not shown) via a hose or the like. The cooling water is supplied from the couplers 28 and 37 through the pipes 26 and 35. Returned to the device again. As a result, heat generation of the boost coil 7 is suppressed.

Next, the operation of the above circuit will be described. First, it is assumed that a predetermined bias is applied from the bias circuit 18 to the gates of the FETs 1 and 2, and the FET 1 is turned on, for example. When the FET 1 is turned on, the current accumulated in the choke coil 9 is supplied to the step-up coil 7 via the intermediate taps 33 and 40, and the supply of this current causes a high voltage across the step-up coil 7 as will be described later. Occurs. As a result, the parallel resonant circuit including the output transformer 9 and the capacitor 11 resonates. The resonance frequency at this time is determined by the inductance of the primary coil 12 of the output transformer 9 and the electrostatic capacity of the capacitor 11. In this parallel resonance state, the resonance circuit (second resonance circuit) including the capacitors 13, 15, 17 or the capacitors 14, 16, 17 and the primary coil 12 (half thereof) of the output transformer 9 resonates. A harmonic wave, for example, the fifth harmonic wave, is generated from this resonant circuit and is superimposed on the sine waveform generated in the parallel resonant circuit. This waveform is supplied to the gate as a drive signal for the FET2 to turn on the FET2. Then, the FETs 1 and 2 are alternately turned on and off, so that a sine waveform having a predetermined frequency and power is output to the secondary side of the output transformer 9. As a result, the work 41 (see FIG. 1) arranged at the tip of the heating coil 10 is heated and, for example, brazing work is performed. The boost coil 7 has a low impedance because the auxiliary coil 25 is fitted in the middle portion of the main coil 24. Therefore, when current is supplied from the choke coil 9 to the middle taps 33, 40, A circulating current flows in a circuit including the intermediate portions 24c and 24d of the coil 24 and the auxiliary coil 25. Due to this current, the current flowing through the booster coil 7 increases, the magnetic flux induced by the coil 7 increases, and the voltage across it increases to a high voltage.

As described above, according to the above-described embodiment, the booster coil 7 having a simple structure can easily obtain a high voltage at both ends thereof, so that the cost of the heating device can be significantly reduced. Further, since the booster coil 7 can be constructed in a relatively small size, the heating device itself can be downsized. In the above embodiment, the diameters of the pipes of the main coil 24 and the auxiliary coil 25 are the same, but the present invention is not limited to this. For example, the diameters may be different, and the pipes having different shapes may be used. You may use (a cross section is elliptical etc.). Further, although the auxiliary coil 25 is integrally formed in the above embodiment, the auxiliary coil 25 may be appropriately changed without departing from the scope of the present invention, for example, the coils 25a and 25b may be separately formed. Needless to say.

[0010]

[Effect of the device]

 As described above in detail, according to the booster coil of the present invention, it is possible to easily obtain a high voltage with a very simple structure in which the auxiliary coil is fitted in the intermediate portion of the single-turn main coil. It is possible to significantly reduce the cost and downsize.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a main part showing an embodiment of a heating device using a boosting coil of the present invention.

FIG. 2 is an exploded perspective view of the present invention.

FIG. 3 is a sectional view of the main part.

[Figure 4] Circuit diagram

[Explanation of symbols]

 7 Booster coil 8 Choke coil 9 Output transformer 10 Heating coil 24 Main coil 25 Auxiliary coil 33, 40 Intermediate tap 31, 32, 38, 39 Tap

Claims (1)

[Scope of utility model registration request] 1. A main coil having a small diameter pipe wound around it, to which a current source is connected, and a main coil having at least two taps provided on both sides of the tap; A booster coil comprising an auxiliary coil wound between taps.