JP2689650B2 - High frequency induction heating device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a high-frequency induction heating device, and in particular, it efficiently and economically heats soaking uniformly even when the object to be heated is asymmetric and the initial temperature is different. The present invention relates to a high frequency induction heating device capable of performing.

[Conventional technology]

Conventionally, as this type of high frequency induction heating apparatus, an apparatus having a configuration shown in FIG. 2 is known. In FIG. 2, reference numeral 10 indicates a high frequency power source, and the high frequency power source 10 is provided with a heating coil 14 arranged above a material to be heated 16 via a resonance capacitor 12.
Connected to. Similarly, the high frequency power supply 20 is connected to the heating coil 24 arranged below the object to be heated 16 via the resonance capacitor 22. The high frequency power supplies 10 and 20 are power supply devices such as an inverter that converts a commercial frequency to a high frequency, and the resonance capacitors 12 and 22 are for improving the power factor of the heating coils 14 and 24, respectively.

Thus, the conventional high-frequency induction heating device is
It consists of two sets of high-frequency power sources 10 and 20 independent of each other, resonance capacitors 12 and 22, and heating coils 14 and 24. An alternating magnetic field is generated by applying a high-frequency current to each heating coil 14 and 24, and this alternating magnetic field is generated. The object to be heated 16 placed inside is heated by the eddy current loss due to the electromagnetic induction effect. In the case of the object 16 to be heated that is asymmetrical in the upper and lower directions, the initial temperature at which heating is started may differ, but even in this case, the conventional high-frequency induction heating device supplies the input power to the upper and lower heating coils 14 and 24. It can be adjusted independently depending on the shape of the object to be heated 16 and the temperature distribution. Such heating from the surface takes a certain amount of time according to the heat capacity of the object to be heated 16, and the heat of the object to be heated 16 is transferred to an even temperature inside.

[Problems to be solved by the invention]

However, in the above-mentioned conventional high-frequency induction heating device, in order to have versatility so as to be able to cope with the size of the object to be heated, a change in shape such as symmetry, and a difference in initial temperature distribution before starting heating, It has a structure that requires at least two independent high-frequency power supplies and their associated equipment (breakers, wiring materials, wiring and piping for cooling). Therefore, there is a problem that the equipment cost is high and the temperature control for operating the two high frequency power supplies is complicated.

Therefore, an object of the present invention is to provide a high-frequency induction heating device that can perform uniform heating at low cost and with simple control with one high-frequency power source equipment even when the object to be heated is asymmetric or the initial temperature is different. There is.

[Means for solving the problem]

In order to achieve the above object, a high frequency induction heating device according to the present invention is a high frequency induction heating device, wherein heating coils driven by a high frequency power source through a resonance capacitor are respectively arranged above and below the object to be heated. In the induction heating device, heating coils arranged above and below the object to be heated are connected in series, these series heating coils are connected to the same power source, and one end of a common high-frequency reactor is connected at the connection point of these heating coils. At the same time, the other end is connected to the power source side connection ends of both the heating coils via the first switch and the second switch, respectively, and the one switch is closed to connect one heating coil in parallel with the high frequency reactor. , Open the other switch to control the current to be lower than that of the heating coil that is not connected in parallel with the high frequency reactor. And said that you configure.

(Operation)

According to the high-frequency induction heating device of the present invention, the high-frequency reactor provided in the upper and lower heating coils in parallel connectable via the respective switches, by opening and closing the switch according to various conditions of the object to be heated, It is possible to partially change the electric power input to the heating object. That is, the heating coil in which the switch is closed and the high frequency reactor is connected in parallel has a smaller current than the heating coil in which the switch is opened and the high frequency reactor is not connected in parallel. Therefore, the electric power supplied to the object to be heated by the heating coil in which the high frequency reactors are connected in parallel can be reduced.

〔Example〕

Next, an embodiment of the high frequency induction heating device according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a block diagram of a high frequency induction heating apparatus showing an embodiment of the present invention. For convenience of explanation, the same parts as those of the conventional apparatus shown in FIG. 2 will be described with the same reference numerals. In FIG. 1, reference numeral 10 indicates a high frequency power source, and one end of the output of the high frequency power source 10 is a resonance capacitor.
It is connected to one end of the heating coil 14 arranged above the object to be heated 16 via 12 and to one end of the high frequency reactor 30 via the switch 32. The other end of the high frequency reactor 30 is connected to a connection point (the middle point of the vertically symmetrical coils 14 and 24) where the other end of the upper heating coil 14 and one end of the lower heating coil 24 are connected in series, and the lower heating coil is connected. The other end of 24 is a high frequency power source 10
And the other end of the high frequency reactor 30 via the switch 34. The switches 32 and 34 are
For example, an electromagnetic contactor or the like.

The operation of the high frequency induction heating device configured as described above will be described below. Generally in high frequency induction heating,
The amount of power input to the object to be heated is proportional to the square of the product nI (ampere turn) of the number of turns n of the heating coil and the current I flowing through the heating coil. Therefore, if the current to the heating coil is reduced, the amount of power input to the object to be heated is reduced accordingly. The present invention utilizes this principle, and the switch 32
(Or 34), the amount of electric power input to the heating coil 14 (or 24) on the side where the high frequency reactor 30 is connected in parallel is reduced by the amount of the current shunted to the high frequency reactor 30.

That is, in the apparatus of the present embodiment, when the object 16 to be heated such as a die is vertically symmetrical and the initial temperature before heating is uniform, the switches 32 and 34 are left open and heated. Even if the object to be heated 16 is vertically asymmetrical or symmetrical, if the initial temperature is different, both the switches 32 and 34 are left open before the heating is started, and after a while, the objects to be heated 16 above and below
When the temperature difference between the two exceeds a predetermined value, the switch 32 (or 34) on the side of the coil 14 (or 24) that heats the heated object 16 with the higher temperature is closed and connected in parallel with the high-frequency reactor 30. By reducing the input power, the upper and lower objects to be heated
Control the temperature of 16 to be uniform.

In this manner, by controlling the on / off of the switches 32 and 34, uniform heating can be realized with only one high-frequency power source equipment regardless of the shape of the object to be heated.

〔The invention's effect〕

As is apparent from the above-described embodiments, according to the high frequency induction heating apparatus of the present invention, the power is partially supplied to the heating coil by inserting the high frequency reactor partially connected in parallel with the heating coil. Therefore, at least two or more high-frequency power supplies and their associated devices are required for only one. For this reason, the cost can be significantly reduced, and the temperature control is also a simple switch on / off control for opening / closing the connection of the high frequency reactor, so that the reliability is improved.

The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and it is needless to say that various design changes can be made without departing from the spirit of the present invention.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a high frequency induction heating apparatus according to the present invention, and FIG. 2 is a block diagram of a conventional high frequency induction heating apparatus. 10,20 …… High frequency power supply 12,22 …… Resonance capacitor 14,24 …… Heating coil 16 …… Heating object 30 …… High frequency reactor 32,34 …… Switch

Claims (1)

(57) [Claims] 1. A high-frequency induction heating apparatus for uniformly heating the object to be heated by arranging heating coils driven by a high-frequency power source via a resonance capacitor respectively above and below the object to be heated. The heating coils arranged in are connected in series, these series heating coils are connected to the same power source, and one end of a common high-frequency reactor is connected at the connection point of these both heating coils, and the other end is connected to the power source side of both heating coils. The connection end and the first switch and the second, respectively
, One of the heating coils that is connected in parallel by closing the one switch and connected in parallel with the high frequency reactor, and the other switch is opened so that the current becomes smaller than that of the heating coil that is not connected in parallel with the high frequency reactor. A high-frequency induction heating device characterized by being configured to control.