JP2000200677A - Electromagnetic induction heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heat a laminated regular filler by electromagnetic induction while preventing the vibration of thin metal plates resulting in particles generation. SOLUTION: An electromagnetic induction heating device comprises a pipe 3 in which a fluid flows, a laminated regular filler 4 provided in the pipe 3 and formed by laminating thin metal plates, a coil 5 arranged so as to locate the laminated regular filler 4 on the inner periphery side thereof and wound on the outer periphery of the pipe 3, a resonance capacitor 7 connected in series to one end of the coil 5, and a high frequency power unit 2 for heating the laminated regular filler 4 by electromagnetic induction by supplying a driving current to the coil in a cycle control system for outputting at a time ratio corresponding to an operation amount while maintaining a fixed driving frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic induction heating device for heating a fluid or the like flowing in a pipe.

[0002]

2. Description of the Related Art In recent years, an electromagnetic induction heating apparatus for heating a fluid in a pipe by utilizing the principle of electromagnetic induction heating has attracted attention in terms of high heating efficiency and safety. As shown in FIG. 3, a conventional electromagnetic induction heating apparatus includes a pipe 52 through which a fluid such as air or water flows, a stacked regular packing body 51 including a large number of thin metal plates housed in the pipe 52, A coil 53 wound around the outer periphery of the pipe 52;
A resonance capacitor 55 connected in series to the
And a high-frequency power supply 54 for supplying a high-frequency current to the resonance capacitor 55. The high-frequency power supply 54 is provided with a freewheel diode (FD) 5.
6, a full-bridge inverter 58 composed of four sets of switching elements 57 connected in anti-parallel, and each switching element 57 is driven by a phase shift control method, and feedback control is performed so that the heating temperature of the fluid becomes a temperature set value. An oscillation control / drive unit 59 is provided.

In the electromagnetic induction heating apparatus configured as described above, the high frequency power supply 54 normally drives each switching element 57 at a driving frequency close to a resonance frequency determined by the inductance L of the coil 53 and the capacitance C of the coil. Thus, the resonance capacitor 55 and the coil 5
3 is supplied with a high-frequency current, and the stacked ordered packing body 51 is heated by electromagnetic induction to heat the fluid to the temperature of the temperature set value.

[0004]

However, in the above-described conventional electromagnetic induction heating apparatus, the laminated regular packing body 51 is a thin metal plate having flexibility and is laminated so as to secure a passage for passing a fluid. Since the entire structured packing 51 cannot be fixed to the pipe 52, the structured packed packing 51 does not have a rigid structure. Therefore, when the waveform of the high-frequency current is distorted, the low-frequency components included in the waveform cause mechanical vibration of the thin metal plates, and the vibration causes the thin metal plates to be fixed to each other or the thin metal plate and the fixed structure in the pipe 52. When the object slides, particles which become a very serious problem for semiconductor manufacturing related equipment are generated.

[0005] Incidentally, the above-mentioned waveform distortion is caused by the driving frequency.
(F_D) And the resonance frequency (f_O) Does not match
Occurs. That is, as shown in FIG._D≒ f_OPlace
In this case, the current waveform is almost sinusoidal
Is not distorted. On the other hand, as shown in FIG.
And f_D<F_OIn the case of, the L and C
Since the cycle due to natural vibration is shorter,
When the diode 56 conducts, the drive current changes at this time,
The flow waveform is distorted. Then, the low frequency included in this current waveform
The components cause the thin metal plate to vibrate. FIG.
As shown in f _D> F_OIn the case of
Because the period of natural oscillation of L and C is longer,
A current change occurs, distorting the current waveform. still,
The distortion rate is f in FIG._D<F_OIs bigger than
No.

Therefore, the driving frequency (f_D) And resonance frequency
(F_O) And (f) _D≒ f_ODrive with
In this case, the generation of particles due to the distortion of the current waveform
Can be prevented. However, electromagnetic induction heating devices require less gold.
Because it is a configuration that electromagnetically heats a thin metal plate of a large amount,
High resonance sharpness (Q = ωL / R) due to low equivalent resistance
Has become. Therefore, f_D≒ f_OWhen driven by
And the resonance characteristics are affected by temperature, etc.
Output current changes drastically even if it changes slightly
Problem occurs.

Further, the above-mentioned conventional electromagnetic induction heating device is
Since the drive current is formed by the phase shift control method, as shown in FIG. 7, even if the drive current is formed at a frequency that does not distort the current waveform at a certain conduction angle, as shown in FIG. A change in the conduction angle due to the phase shift during operation causes distortion in the current waveform. In addition, the phase shift control method has a disadvantage that the relationship between the manipulated variable and the output power cannot be linear because the output current has a complicated waveform shape.

Accordingly, the present invention has been made in view of such a conventional problem, and it is an object of the present invention to provide an electromagnetic induction heating method for a layered packed body while preventing vibration of a thin metal plate which causes particles. It is intended to provide an electromagnetic induction heating device capable of performing the above.

[0009]

According to a first aspect of the present invention, there is provided an electromagnetic induction heating apparatus comprising: a pipe through which a fluid flows; and a thin metal plate provided in the pipe. A stacked ordered packing body formed by stacking, the stacked ordered packing body is disposed so as to be located on the inner peripheral side, a coil wound around the outer periphery of the pipe, and connected in series to one end of the coil. And a high frequency for electromagnetically heating the stacked packed body by supplying to the coil by a resonance capacitor and a cycle control method of outputting a drive current at a constant drive frequency at a time ratio according to an operation amount. A power supply device.

According to the above configuration, while controlling the electromagnetic induction heating by changing the time ratio of the output of the drive current while maintaining the frequency of the drive current at a constant drive frequency, the conventional drive frequency is reduced. Unlike the phase shift control method in which the control is performed by changing, the current waveform of the drive current is not distorted during the control and the low frequency component is not included. With this, once the driving frequency is set to a frequency that does not include the low-frequency component, mechanical vibration of the stacked ordered packing body due to the current waveform of the low-frequency component does not occur during control, so that the generation of particles is sufficiently reduced. Electromagnetic induction heating of the stacked structured packing can be performed while preventing the stacked packing.

According to a second aspect of the present invention, there is provided the electromagnetic induction heating apparatus according to the first aspect, wherein the high-frequency power supply includes an inverter unit having a switching element in which a freewheel diode is connected in anti-parallel, An oscillation control / drive unit that outputs the drive current by driving the switching element at a drive frequency sufficiently higher than the resonance frequency due to the capacitance of the capacitor and the inductance of the coil.

[0012] According to the above configuration, since the drive current is supplied at a drive frequency sufficiently higher than the resonance frequency to perform electromagnetic induction heating, the free-wheel diode is set at a drive frequency lower than the resonance frequency. Does not cause waveform distortion due to conduction. Therefore, generation of particles can be more sufficiently prevented by preventing the vibration of the stacked ordered packing body caused by the conduction of the freewheel diode.

According to a third aspect of the present invention, there is provided the electromagnetic induction heating apparatus according to the first or second aspect, wherein the high-frequency power supply includes:
Further, a soft start / soft stop circuit is provided which gradually increases the amount of current when the supply of the drive current is started, and gradually reduces the amount of current when the supply of the drive current is stopped. . According to the above configuration, the stacked ordered packing material shifts the mechanical resonance frequency due to a rapid current change (change in magnetic field strength),
Since no thermal distortion is generated, the vibration of the ordered packing body can be further reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 1, the electromagnetic induction heating device according to the present embodiment includes a heating device main body 1 that heats a fluid such as a gas or a liquid, and a high-frequency power supply device 2 that supplies power to the heating device main body 1. have.
The heating device main body 1 includes: a pipe 3 through which a fluid flows in the arrow direction; a stacked regular packing 4 provided in the pipe 3 and formed by stacking thin metal plates such as stainless steel and titanium alloy; A coil 5 wound around the outer circumference of a pipe 3, a resonance capacitor 7 connected in series to one end of the coil 5, A temperature detector 6 provided in the pipe 3 on the downstream side of the pipe 3 to detect the temperature of the fluid.

The above coil 5 and resonance capacitor 7
Is connected to the high-frequency power supply 2. The high-frequency power supply device 2 includes an inverter unit 8 that converts DC power into AC power, and an oscillation control unit that drives and controls the inverter unit 8.
It has a driving unit 9 and a rectifying unit 10 that rectifies AC power and supplies the rectified AC power to the inverter unit 8. The rectifier 10 is a rectifier bridge circuit 1 in which four diodes are connected in a bridge.
8 and a choke input type smoothing circuit 19 composed of a coil and a capacitor. It is designed to generate DC power.

The inverter 8 to which DC power is supplied from the rectifier 10 includes a switching element 11 such as an IGBT whose on / off state is switched by a drive signal, and a freewheel connected in antiparallel to the switching element 11. It is configured as a full bridge type having four sets of diodes (FD) 12. Each switching element 11 has an oscillation control / drive unit 9 that outputs a drive signal.
Is connected.

The above-mentioned oscillation control / drive section 9 supplies the heating device main body 1 with electric power corresponding to an operation amount which is a difference between a temperature detection signal from the temperature detector 6 and a temperature set value, so that the fluid The configuration is such that feedback control is performed so that the temperature becomes a temperature set value.

That is, the oscillation control / drive section 9 has a cycle control circuit 13 that operates in a cycle control system.
Note that the cycle control method is, as shown in FIG.
This is a method of outputting a drive current with a constant frequency and a constant conduction angle at a time ratio according to the operation amount. Then, as shown in FIG. 1, the cycle control circuit 13 operating in this manner
Is to set the frequency of the drive signal to a drive frequency (f _D ) sufficiently higher than the resonance frequency (f _O ) of the inductance L of the coil 5 and the capacitance C of the resonance capacitor 7, so that the stacked ordered packing 4 The generation of mechanical vibration is suppressed.

The oscillation control / drive section 9 has a soft start / soft stop circuit 14 for preventing a sudden change in the current when the supply of the drive current to the coil 5 is started or stopped. The soft-start / soft-stop circuit 14 includes a delay circuit 15 for setting the current change rate at the start and stop of the supply of the drive current, and a conduction angle control circuit 16 for setting the conduction angle of the drive current based on the current change rate. And a software process for gradually increasing the current amount when the supply of the drive current to the coil 5 is started, and gradually decreasing the current amount when the supply of the drive current is stopped.

The operation of the electromagnetic induction heating device in the above configuration will be described. First, an operator inputs a desired temperature set value to a control panel (not shown). After this,
When the operator presses the heating start switch on the control panel,
The control panel supplies and flows the fluid into the pipe 3 of the heating device main body 1 and operates the high-frequency power supply device 2 while outputting the temperature set value.

When the high-frequency power supply 2 starts operating, the cycle control circuit 13 generates a drive signal oscillating at a drive frequency (f _D ) sufficiently higher than the resonance frequency (f _O ). Then, an operation amount, which is a difference between the temperature detection signal from the temperature detector 6 and the temperature set value, is taken in, and a time ratio corresponding to power corresponding to the operation amount is obtained. The output and the stop of the drive signal are alternately repeated so as to output the drive signal.

The above drive signal has the overall shape of the signal shown in FIG.
(A) is input to the delay circuit 15 while forming a square wave. The delay circuit 15 detects the start and end of the drive signal by detecting the start and end of the input of the drive signal, respectively. Then, the outer shape of the drive signal is changed so that the drive current increases at a predetermined current change rate at the leading end portion of the drive signal, and the outer shape of the drive signal decreases at a predetermined current change rate at the end portion. To change. The drive signal whose tip and end portions have been changed in this way has an outer shape of the entire signal shown in FIG.
The signal is input to the conduction angle control circuit 16 while forming a trapezoidal waveform shown in FIG. Thereafter, by conduction angle control circuit 16 outputs while controlling the drive signal so that the conduction angle corresponding to trapezoidal contour, driving each switching element 11, the driving frequency from the inverter unit 8 (f _D ) Is supplied to the heating device main body 1 at the above-mentioned time ratio.

The above driving current is supplied to the coil 5 via the resonance capacitor 7 of the heating device main body 1. Then, the coil 5 generates a magnetic field every time the drive current is conducted, heats the ordered packed body 4 by electromagnetic induction, and the ordered packed body 4 heats the fluid by heat exchange. Then, the temperature of this fluid is detected by the temperature detector 6, and the temperature detector 6
The feedback control of the time ratio of the output of the drive current is performed so that the temperature detection signal output from the control circuit matches the temperature set value.

At this time, since the driving current supplied to the coil 5 is set to a driving frequency (f _D ) sufficiently higher than the resonance frequency (f _O ), the resonance frequency (f
_Unlike the case where the driving frequency (f _D ) is set lower than _O ), the waveform distortion due to the conduction of the freewheel diode 12 does not occur. Therefore, since a low frequency component is not added to the current waveform of the drive current, the magnetic field generated corresponding to the drive current does not cause the stacked ordered packing body 4 to be electromagnetically induced by the low frequency component to vibrate.

As shown in FIG. 2B, the drive current is gradually increased from the minimum amount (0%) to the maximum amount (100%) at the start of the supply, and then is increased to the maximum amount (100%).
%), And is gradually reduced to the minimum amount (0%) when the supply is stopped. Therefore, the stacked ordered packing body 4 does not move the mechanical resonance frequency or generate thermal distortion due to a sudden current change (change in magnetic field strength), and the vibration of the stacked ordered packing body 4 is further reduced. ing.

As a result, as shown in FIG. 1, the laminated packed body 4 hardly generates any mechanical vibration during electromagnetic induction heating. The generation of particles due to sliding with the fixed structure in 3 is sufficiently prevented.

As described above, the electromagnetic induction heating apparatus according to the present embodiment supplies the coil 5 to the coil 5 by the cycle control system in which the drive current is output at a time ratio corresponding to the operation amount while maintaining the drive current at a constant drive frequency. Since the stacked structured packing 4 is configured to be heated by electromagnetic induction, the current waveform of the driving current is distorted during the control as in the conventional phase shift control method in which the driving frequency is changed and controlled. And does not contain low frequency components. Thus, once the driving frequency is set to a frequency that does not include a low-frequency component, mechanical vibration of the stacked ordered packing body 4 due to the current waveform of the low-frequency component does not occur during control, so that the generation of particles is sufficiently reduced. In this way, the stacked ordered packing body 4 can be heated by electromagnetic induction.

In the present embodiment, the inverter unit 8 is configured as a full-bridge type, but is not limited to this, and may be configured as a half-bridge type.

[0029]

According to the first aspect of the present invention, there is provided an electromagnetic induction heating apparatus, comprising: a pipe through which a fluid flows; and a stacked regular packing body provided in the pipe and formed by stacking thin metal plates. A coil wound around an outer periphery of the pipe, a resonance capacitor connected in series to one end of the coil, and a drive current of a constant value. A high-frequency power supply for supplying electromagnetic waves to the stacked packing by electromagnetic induction by supplying the coil to the coil by a cycle control method of outputting a time ratio according to the operation amount while maintaining the frequency.

According to the above configuration, the electromagnetic induction heating is controlled by changing the time ratio of the output of the drive current while maintaining the frequency of the drive current at a constant drive frequency. Unlike the phase shift control method in which the control is performed by changing, the current waveform of the drive current is not distorted during the control and the low frequency component is not included. With this, once the driving frequency is set to a frequency that does not include the low-frequency component, mechanical vibration of the stacked ordered packing body due to the current waveform of the low-frequency component does not occur during control, so that the generation of particles is sufficiently reduced. This has the effect that the stacked structured packing can be heated by electromagnetic induction while preventing it.

According to a second aspect of the present invention, there is provided the electromagnetic induction heating apparatus according to the first aspect, wherein the high-frequency power supply includes an inverter unit having a switching element in which a freewheel diode is connected in anti-parallel, An oscillation control / drive unit that outputs the drive current by driving the switching element at a drive frequency sufficiently higher than the resonance frequency due to the capacitance of the capacitor and the inductance of the coil.

According to the above configuration, the drive current is supplied at a drive frequency sufficiently higher than the resonance frequency to perform the electromagnetic induction heating, so that the free wheel diode is set at a drive frequency lower than the resonance frequency. Does not cause waveform distortion due to conduction. Therefore, by preventing the vibration of the stacked packed body caused by the conduction of the freewheel diode, it is possible to more effectively prevent the generation of particles.

According to a third aspect of the present invention, there is provided the electromagnetic induction heating apparatus according to the first or second aspect, wherein the high-frequency power supply includes:
Further, a soft start / soft stop circuit is provided which gradually increases the current amount when the supply of the drive current is started, and gradually decreases the current amount when the supply of the drive current is stopped. According to the above configuration, since the stacked ordered packing does not move the mechanical resonance frequency or generate thermal distortion due to a sudden current change (change in magnetic field strength), the vibration of the stacked ordered packing is reduced. There is an effect that it can be further reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of an electromagnetic induction heating device.

FIGS. 2A and 2B show a state of a drive current (drive signal) in a cycle control method, wherein FIG. 2A shows a state before software processing and FIG. 2B shows a state after software processing.

FIG. 3 is a block diagram of a conventional electromagnetic induction heating device.

FIG. 4 is an explanatory diagram showing a relationship between a drive signal and a drive current in a phase shift control method.

FIG. 5 is an explanatory diagram showing a relationship between a drive signal and a drive current in a phase shift control method.

FIG. 6 is an explanatory diagram showing a relationship between a drive signal and a drive current in a phase shift control method.

FIG. 7 is an explanatory diagram showing a relationship between a drive signal and a drive current in a phase shift control method.

FIG. 8 is an explanatory diagram showing a relationship between a drive signal and a drive current in the phase shift control method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating device main body 2 High-frequency power supply device 3 Pipe 4 Stacked ordered packing material 5 Coil 6 Temperature detector 7 Resonance capacitor 8 Inverter part 9 Oscillation control / drive part 10 Rectification part 11 Switching element 12 Freewheel diode 13 Cycle control circuit 14 Soft Start / soft stop circuit 15 Delay circuit 16 Conduction angle control circuit 17 AC power supply 18 Rectifier bridge circuit 19 Smoothing circuit

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshitaka Uchibori 19-21 Misawacho, Ibaraki-shi, Osaka Inside Seta Giken Co., Ltd. Within Mullon Co., Ltd. (72) Inventor Shinji Oku 10 Hanazono Todocho, Ukyo-ku, Kyoto, Kyoto O Within Muroron Co., Ltd. Company F term (reference) 3K059 AA06 AA07 AA14 AA15 AB26 AB28 AC07 AC12 AC15 AC26 AC33 AC35 AC54 AD22 AD23 BD05 BD10 CD05 CD07 CD09 CD10 CD23 CD44 CD73 CD77

Claims (3)

[Claims] 1. A pipe through which a fluid flows, a stacked ordered packing body provided in the pipe and formed by stacking thin metal plates, and a stacked ordered packing body positioned on an inner peripheral side. A coil wound around the outer circumference of the pipe, a resonance capacitor connected in series to one end of the coil, and outputting a drive current at a time ratio according to an operation amount while maintaining a constant drive frequency. A high-frequency power supply for supplying electromagnetic waves to the stacked ordered packing by electromagnetic induction by supplying the coils to the coil by a cycle control method. 2. The high-frequency power supply device includes: an inverter unit having a switching element in which a freewheel diode is connected in anti-parallel; and a drive sufficiently higher than a resonance frequency due to a capacitance of the resonance capacitor and an inductance of the coil. The electromagnetic induction heating apparatus according to claim 1, further comprising an oscillation control / drive unit that outputs the drive current by driving the switching element at a frequency. 3. The soft-start / soft-stop device according to claim 1, wherein the high-frequency power supply further increases a current amount when the supply of the drive current is started, and gradually reduces the current amount when the supply of the drive current is stopped. 3. The electromagnetic induction heating device according to claim 1, further comprising a circuit.