JP2020191225A - Heater - Google Patents

Abstract

To provide a heater using magnetic resonance operating at a low frequency, the heater being capable of solving the problem of electrode wear in direct electrical heating and the problem of initial cost rise and energy loss caused by a transformer in high frequency induction heating and low frequency induction heating.SOLUTION: A heater 1 of the present invention comprises: a primary circuit 10; a secondary circuit 20 that is coupled with the primary circuit 10 via magnetic resonance; and a heat insulating wall 30 that separates the primary circuit 10 from the secondary circuit 20 by surrounding the secondary circuit 20 and has permeability for a magnetic field of magnetic resonance. The primary circuit 10 includes: a primary magnetic core 11; and a power supply coil 12 that is disposed around the primary magnetic core 11 to receive AC current. The secondary circuit 20 includes: a secondary magnetic core 21 that is coupled with the primary magnetic core 11 via magnetic resonance; a conductive heating object 22 that is short-circuited and disposed in a loop shape around the secondary magnetic core 21; and a secondary side resonance capacitor 23 that is electrically connected to the heating object 22.SELECTED DRAWING: Figure 1

Description

The present invention relates to a heating device, and more particularly to a device capable of heating an object to be heated to a high temperature by using a commercial power source.

High-temperature heat treatment is an important processing process for industrial members such as metals, and various heat treatment facilities are used according to the shape and processing content of the members. Fossil fuels such as petroleum and natural gas are also used in large high-temperature heat treatment facilities, but some smaller facilities use electricity for convenience.

As equipment that uses electricity, a direct energization heating type equipment is known in which an electrode is brought into contact with a heating target to energize the object, and Joule heat due to internal resistance is used to heat the equipment from the inside. This equipment has an advantage that the heating target can be heated evenly from the inside with a simple equipment configuration. However, as the equipment is used for a longer period of time, the electrodes are consumed. Due to this consumption, there is a problem of pushing up the running cost. Further, in order to surely suppress the risk of electrode consumables being mixed into the object to be heated, it is necessary to propose equipment by another method.

As a facility of a system different from the direct energization heating system, a facility of a high frequency induction heating system is known. As an example of this equipment, in addition to equipment that heats the object to be heated from the inside by Joule heat due to eddy current, equipment that arranges the object to be heated inside the induction coil, or equipment that arranges the object to be heated near the axial direction of the induction coil, etc. are known. Has been done. Since this method does not involve the consumption of the electrodes, it has an advantage that the risk of the consumables of the electrodes being mixed into the object to be heated can be surely suppressed. On the other hand, there are improvement issues such as exposure of high frequencies to workers, noise contamination in peripheral devices, and notification of installation.

It has been proposed to use a low frequency for an induction heating device as a means for solving both the problem of electrode wear in the direct energization method and the problem associated with the use of high frequency in the high frequency induction heating method. For example, Patent Document 1 applies a low-frequency magnetic field to a magnetic core forming a closed-loop circuit to apply a secondary current to a metal to be heated contained in a heat insulating container arranged around the magnetic core. Disclosed is an induction heating device that induces and generates Joule heat. Since the induction heating device described in Patent Document 1 does not use an electrode because it generates an induced current directly inside the object to be heated, it can solve the problem of electrode wear in the direct energization method. Further, since the induction heating device described in Patent Document 1 uses a low frequency, the problem associated with the use of a high frequency in the high frequency induction superheating method can be solved.

Japanese Unexamined Patent Publication No. 4-006788

The device disclosed in Patent Document 1 can provide an alternating magnetic flux of an appropriate frequency to an object to be heated by an alternating magnetic flux generating device using a movable core rotated by a driving device, and can improve the heating efficiency. However, consideration for energy loss generated in this alternating magnetic flux generator is not sufficient.

Further, in the device disclosed in Patent Document 1, a part of the alternating magnetic flux becomes a leakage flux due to magnetic leakage, and the device is consumed without flowing an induced current inside the object to be heated. Consideration for the leakage inductance caused by this magnetic leakage is also insufficient.

The present invention has been made in view of the above, and can solve both the problem of electrode wear in direct energization heating and the problem of high-frequency electromagnetic waves in high-frequency induction heating, and the initial cost brought about by a transformer in high-frequency induction heating. The problem of rising and energy loss can be solved, the problem of energy loss due to leakage magnetic flux in low frequency induction heating can be solved, and the heat generated by the object to be heated is not wasted to heat the magnetic core or the entire heating device. It is an object of the present invention to provide a heating device using magnetic field resonance that operates at a low frequency.

As a result of diligent studies to solve the above problems, the present inventors have used a non-contact type power supply device and a direct energization heating device, and separated the two devices with a heat insulating wall to provide the non-contact type power supply. We have found that the above object can be achieved by making the power receiving equipment of the device a special structure, and have completed the present invention. Specifically, the present invention provides the following.

The present invention relates to a heating device. The heating device surrounds the primary circuit, the secondary circuit coupled to the primary circuit by magnetic field resonance, and the secondary circuit to separate the primary circuit from the secondary circuit, and the magnetic field of the magnetic field resonance. The primary circuit has a primary magnetic core and a feeding coil arranged around the primary magnetic core and receiving an AC current having an operating frequency of 400 Hz or less. The secondary circuit includes a secondary magnetic core coupled to the primary magnetic core by magnetic field resonance, a conductive heating object short-circuited around the secondary magnetic core and arranged in a loop, and the above. It has a secondary resonance capacitor that is electrically connected to the object to be heated.

In the heating device according to the present invention, first, the feeding coil receives an alternating current having an operating frequency of 400 Hz or less in the primary circuit. By this power reception, a fluctuating magnetic field is generated in the primary magnetic core arranged substantially in the center of the feeding coil. Then, the fluctuating magnetic field reaches the secondary magnetic core of the secondary circuit from the primary magnetic core. Although the primary circuit and the secondary circuit are separated by a heat insulating wall, the heat insulating wall is transparent to the magnetic field of magnetic field resonance, so that the magnetic coupling between the primary magnetic core and the secondary magnetic core is , Not disturbed. The fluctuating magnetic field generated in the primary magnetic core can reach the secondary magnetic core through a magnetic field permeable insulating wall.

Subsequently, in the secondary circuit, when the fluctuating magnetic field reaches the secondary magnetic core, the inside of the conductive heating object is short-circuited around the secondary magnetic core and arranged in a loop according to the law of electromagnetic induction. Generates an induced current. Since the object to be heated has an internal resistance, when an induced current is generated inside the object to be heated, Joule heat is applied to the inside of the object to be heated.

According to the heating device according to the present invention, since it is not necessary to bring the electrode into contact with the object to be heated, there are problems of electrode wear in direct energization heating and various problems caused by electrode wear (increasing running cost, electrode wear). (Reduction of risk of contamination) can be solved.

Further, the operating frequency of the alternating current used for receiving power from the feeding coil is 400 Hz or less, which is a low frequency band. According to the heating device according to the present invention, since the object to be heated can be heated from the inside by Joule heat without using the alternating current in the high frequency band, various problems in high frequency induction heating (exposure of high frequency to workers, peripheral devices). It is possible to solve the problem of noise mixing in the radio frequency and notification required for installation).

Next, the solution of energy loss in high frequency induction heating and low frequency induction heating will be described. According to Non-Patent Document 1 (“Efficiency and Magnetic Flux in Magnetic Resonance Coupling”, Journal of AEM Society of Japan, vol.24, No.4, pp.317-322 (2016)), the resonance frequency of the heating device is ω, and the primary circuit resistance, _{inductance, r 1, L 1, C} 1 and the capacitance, respectively, _r 2 secondary circuit of the resistance, inductance, capacitance, _{respectively,} L 2, _{C 2,} load _{R L,} the exciting inductance _{L m,} the coupling coefficient When k is, the efficiency η of power transmission is obtained by the equation (1).
^{_{η = (ωL m) 2 R}} L / [{(r 2 + R L) 2 + (ωL 2 -1 / ωC 2) 2} r 1
^{_{+ (ΩL m) 2 r 2}} + (ωL m) 2 R L] ··· (1)

When the load _{R L} is equal to the optimum load _{R Lopt} indicated by equation (2), Equation (1) is an ideal magnetic resonance condition.
^{_{R Lopt = {r 2 2 +}} (r 2 / r 1) (ωL m) 2 + (ωL 2 -1 / ωC 2) 2} 1/2 ··· (2)

At this time, C ₂ , ω, and L ₂ satisfy the equation (3).
C ₂ = 1 / (L ₂ ω ² ) ・ ・ ・ (3)

According to the heating device according to the present invention, the secondary resonance capacitor is electrically connected to the object to be heated in the secondary circuit. Then, since the magnetic field resonance condition can be achieved by compensating the leakage inductance with the capacitance (capacitance) of the secondary resonance capacitor, the heating device according to the present invention can solve the decrease in energy efficiency due to the leakage flux. ..

Next, a solution to the problem of suppressing the Joule heat generated by the object to be heated from being wasted for purposes other than heating the object will be described. In the heating device according to the present invention, the secondary circuit is surrounded by a heat insulating wall. The presence of the heat insulating wall can prevent the Joule heat generated by the object to be heated from flowing out to the outside of the secondary circuit. Therefore, according to the heating device according to the present invention, the Joule heat generated by the object to be heated heats the entire heating device outside the secondary circuit including each member (primary magnetic core, feeding coil) on the primary circuit side. It can be suppressed from being wasted.

As described above, according to the present invention, both the problem of electrode wear in direct energization heating and the problem of high frequency electromagnetic waves in high frequency induction heating can be solved, and transformers in high frequency induction heating and low frequency induction heating can be used. A heating device using magnetic field resonance that operates at low frequencies can solve the problems of increased initial cost and energy loss, and can prevent the heat generated by the object to be heated from being wasted to heat the magnetic core and the entire heating device. Can be provided.

In the heating device according to the present invention, it is preferable that the primary circuit further includes a primary resonance capacitor that is electrically connected to the feeding coil.

The primary resonance capacitor reduces the reactance of the primary circuit, thereby increasing the main magnetic flux that couples the primary and secondary magnetic cores. By strengthening the main magnetic flux, electromagnetic induction in the secondary circuit is strengthened, and the efficiency of feeding power to the object to be heated can be further improved.

In the heating device according to the present invention, it is preferable that the object to be heated is arranged inside the heat insulating member.

According to this heating device, since the presence of the heat insulating member can prevent the Joule heat generated by the object to be heated from flowing out to the outside of the heat insulating member, the secondary circuit including each member on the primary circuit side In addition to the external members, it is possible to prevent the Joule heat generated by the object to be heated from being wasted in order to heat each member (secondary magnetic core and secondary resonance capacitor) on the secondary circuit side.

In the heating device according to the present invention, it is preferable that the heating target has a ring shape, a pipe shape, or a cable shape, and the heating target is arranged in a loop shape.

By arranging ring-shaped, pipe-shaped, or cable-shaped heating objects in a loop shape or the like, an electric circuit in which the heating objects are short-circuited is formed. Therefore, the fluctuating magnetic field of the secondary magnetic core can generate an induced current in the object to be heated by the law of electromagnetic induction.

In the heating device according to the present invention, it is also preferable that the secondary circuit further has a ring-shaped container. In this case, the object to be heated is a conductive liquid or a conductive powder, and the ring-shaped container is provided in a ring shape around the secondary magnetic core and can accommodate the object to be heated inside. It is preferably configured in.

By accommodating a liquid or powder heating object in a ring-shaped container, an electrical circuit in which the heating object is short-circuited is formed. Therefore, the fluctuating magnetic field of the secondary magnetic core generates an induced current in the object to be heated according to the law of electromagnetic induction.

The heating device according to the present invention adjusts the amount of power supplied to the power feeding coil based on the temperature measuring means for directly or indirectly measuring the temperature of the object to be heated and the temperature measured by the temperature measuring means. It is preferable to further provide a power supply amount adjusting means.

According to this heating device, the temperature of the object to be heated can be measured directly or indirectly, and the current or phase of the power supply source (power supply, etc.) that supplies power to the power supply coil can be controlled based on the measurement result. More efficient power transmission and heat treatment of the object to be heated can be performed.

Examples of the temperature measuring means for directly measuring the temperature of the object to be heated include a temperature sensor and the like. Further, as a temperature measuring means for indirectly measuring the temperature of the object to be heated, an ammeter connected to the feeding coil and the like can be mentioned. The change in electrical resistance applied to the feeding coil can be calculated using the ammeter, and the temperature change can be obtained from the calculation result.

In addition, if the heating device is equipped with a temperature measuring means, stable heat treatment such as keeping the temperature of the object to be heated below a certain level, keeping it within a certain range, or keeping the temperature rise rate within a certain range is possible. It becomes. As a result, metal can be annealed, tempered, carburized, and the like.

In the heating device according to the present invention, it is preferable that the magnetic pole area of the primary magnetic core is larger than the cross-sectional area of the feeding coil and the magnetic pole area of the secondary magnetic core is larger than the cross-sectional area of the feeding coil.

Since the magnetic pole area of the primary magnetic core is larger than the cross-sectional area of the feeding coil, the first magnetic flux loop emitted from the primary magnetic core is reduced. Further, since the magnetic pole area of the secondary magnetic core is larger than the cross-sectional area of the feeding coil, the second magnetic flux loop emitted from the secondary magnetic core is reduced. The decrease of the first magnetic flux loop and the second magnetic flux loop strengthens the magnetic field coupling between the primary magnetic core and the secondary magnetic core. Therefore, the coupling coefficient k between the feeding coil on the primary circuit side and the heating target on the secondary circuit side can be brought close to the ideal value of 1, and the feeding efficiency to the heating target can be further improved.

It is also preferable that the heating device according to the present invention includes a variable transformer electrically connected to the power feeding coil.

The variable transformer enables frequency selection according to the electrical characteristics of the object to be heated, facilitating the achievement of magnetic field resonance conditions. Further, by combining the variable transformer with the temperature measuring means, it is possible to change the frequency of the alternating current supplied to the feeding coil when the electrical characteristics of the object to be heated change with heating. To do. By this frequency change, the magnetic field resonance condition is maintained even if the electrical characteristics of the object to be heated change with heating, and the efficiency of feeding the object to be heated can be further improved.

According to the present invention, both the problem of electrode wear in direct energization heating and the problem of high frequency electromagnetic waves in high frequency induction heating can be solved, and the problem of energy loss due to leakage magnetic field in high frequency induction heating and low frequency induction heating can also be solved. It is possible to provide a heating device using magnetic field resonance that operates at a low frequency so that the heat generated by the heating object is not wasted to heat the magnetic core or the entire heating device.

It is a schematic schematic diagram for demonstrating the heating apparatus 1 which concerns on this Embodiment. It is a schematic schematic diagram for demonstrating the heating apparatus 1'corresponding to the 1st modification of this embodiment. It is a schematic schematic diagram for demonstrating the heating apparatus 1 ″ which concerns on the 2nd modification of this embodiment.

Hereinafter, specific embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments, and the present invention is carried out with appropriate modifications within the scope of the object of the present invention. can do.

<Heating device 1>
FIG. 1 is a schematic schematic view for explaining the heating device 1 according to the present embodiment. The heating device 1 includes at least a primary circuit 10, a secondary circuit 20, and a heat insulating wall 30 that surrounds the secondary circuit 20 and separates the primary circuit 10 from the secondary circuit 20.

[Primary circuit 10]
The primary circuit 10 has at least a primary magnetic core 11 and a feeding coil 12.

[Primary magnetic core 11]
The primary magnetic core 11 is not particularly limited as long as it is a magnetic material. The primary magnetic core 11 has a higher magnetic permeability and a lower coercive force than the hard magnetic material so that the primary magnetic core 11 is magnetized along the fluctuation of the magnetic field generated by the feeding coil 12 and the coercive force does not hinder the fluctuation of the magnetic field. It is preferably a soft magnetic material.

In the present embodiment, the hard magnetic material means a so-called magnet, which has a large coercive force and is used as a permanent magnet. On the other hand, a soft magnetic substance is a material that sticks to a magnet, and is a substance that quickly loses its magnetism and returns to its original state when the external magnetic field is removed.

Specific examples of the primary magnetic core 11 include pure iron, silicon steel, and stainless steel. In order to further reduce the energy loss due to eddy currents, iron oxidation has a smaller iron loss than pure iron, silicon steel, and stainless steel. Material-based ferrite, cobalt-based amorphous steel, sendust, permalloy, and the like may be used.

Above all, since silicon and iron are used as raw materials, the primary magnetic core 11 is preferably silicon steel because it is relatively cheaper than iron oxide ferrite and the like and has a higher magnetic permeability than pure iron.

In order to transmit the first magnetic flux emitted from the primary magnetic core 11 to the secondary magnetic core 21, the shape of the primary magnetic core 11 is such that the magnetic material is bent into a U shape to form the secondary magnetic core 21 described later. It is preferable that the shapes are opposed to each other. By facing each other, the first magnetic flux loop emitted from the primary magnetic core 11 can be reduced.

Further, in order to increase the efficiency of generating the first magnetic flux along the feeding coil 12, the magnetic material is processed as a directional electromagnetic steel plate that is easily magnetized in a specific direction, and the direction that is easily magnetized and the feeding coil 12 It is also preferable to align the directions of the magnetic fields generated by.

[Feed supply coil 12]
The power feeding coil 12 is arranged around the primary magnetic core 11 and is composed of a coil-shaped conductor that receives an alternating current having an operating frequency of 400 Hz or less. By this power reception, a fluctuating magnetic field is generated in the primary magnetic core 11 arranged substantially in the center of the power feeding coil 12. Then, the fluctuating magnetic field reaches the secondary magnetic core 21 of the secondary circuit 20 from the primary magnetic core 11.

The power feeding coil 12 may be a coil-shaped conductor that receives an alternating current to generate a fluctuating magnetic field, and the material and detailed structure are not particularly limited.

The operating frequency of the alternating current used to receive power from the feeding coil 12 is 400 Hz or less. If the operating frequency exceeds 400 Hz, the transmission efficiency when the primary magnetic core 11 and the secondary magnetic core 21 are each made of silicon steel plate is sharply lowered, which is not preferable.

The operating frequency is more preferably 300 Hz or less, further preferably 200 Hz or less, and even more preferably 100 Hz or less. And since a commercial power source can be used, the operating frequency is particularly preferably 50 Hz or 60 Hz.

According to the heating device 1 according to the present invention, since the object 22 to be heated can be heated from the inside by Joule heat without using the alternating current in the high frequency band, various problems in high frequency induction heating (exposure of high frequency to workers, It is possible to solve the problem of noise mixing in peripheral devices and notification required for installation).

Although the lower limit of the operating frequency is not particularly limited, the operating frequency is preferably 5 Hz or higher, preferably 10 Hz or higher, because a larger capacitance is required for suitable heating at a lower operating frequency. More preferably.

[Primary side resonance capacitor 13]
Although not an essential configuration, the primary circuit 10 preferably includes a primary resonance capacitor 13. The primary resonance capacitor 13 has a function of reducing the reactance of the primary circuit 10 and thereby strengthening the main magnetic flux that couples the primary magnetic core 11 and the secondary magnetic core 21. By strengthening the main magnetic flux, the electromagnetic induction in the secondary circuit 20 is strengthened, and the power feeding efficiency to the heating object 22 can be further improved.

[Variable transformer 16]
Although not an essential configuration, the primary circuit 10 preferably includes a variable transformer 16. Since the variable transformer 16 enables frequency selection according to the electrical characteristics of the object to be heated 22, it facilitates the achievement of the magnetic field resonance condition. Further, by combining the variable transformer 16 with the temperature measuring means 25, it is possible to change the frequency of the alternating current supplied to the feeding coil 12 when the electrical characteristics of the object to be heated 22 change with heating. To do. By this frequency change, the magnetic field resonance condition is maintained even if the electrical characteristics of the heating object 22 change with heating, and the power supply efficiency to the heating object 22 can be further improved.

[Secondary circuit 20]
The secondary circuit 20 includes at least a secondary magnetic core 21, a heating object 22, and a secondary resonance capacitor 23.

[Secondary magnetic core 21]
The secondary magnetic core 21 is coupled to the primary magnetic core 11 by magnetic field resonance. The secondary magnetic core 21 is not particularly limited as long as it is a magnetic material, like the primary magnetic core 11. The secondary magnetic core 21 has a higher magnetic permeability and a lower coercive force than the hard magnetic material so that the secondary magnetic core 21 is magnetized along the fluctuation of the magnetic field generated by the feeding coil 12 and the coercive force does not hinder the fluctuation of the magnetic field. It is preferably a soft magnetic material. The material of the secondary magnetic core 21 is not particularly limited as long as it satisfies these conditions, and typical examples thereof include pure iron, silicon steel, stainless steel, etc., but energy loss due to eddy current is caused. In order to further reduce the iron loss, iron oxide-based ferrite, cobalt-based amorphous material, sendust, permalloy, etc., which have a smaller iron loss than pure iron, silicon steel, or stainless steel, may be used.

The secondary magnetic core 21 receives a fluctuating magnetic field generated in the primary magnetic core 11 and reached over the heat insulating wall 30. In order to receive the fluctuating magnetic field more efficiently, the magnetic material is processed as a grain-oriented electrical steel sheet that is easily magnetized in a specific direction, and the direction that is easily magnetized and the vertical direction of the loop formed by the object 22 to be heated. It is also preferable to align them.

Since the temperature of the secondary magnetic core 21 rises with the heat treatment and oxidation proceeds, it is also preferable that the secondary magnetic core 21 is a ferritic stainless steel which is a soft magnetic material having corrosion resistance.

[Heating object 22]
The object to be heated 22 is a conductor short-circuited around the secondary magnetic core 21 and arranged in a loop. By arranging the ring-shaped, pipe-shaped, or cable-shaped heating object 22 in a loop shape or the like, the heating object 22 is short-circuited to form an electric circuit. Therefore, the fluctuating magnetic field of the secondary magnetic core 21 can generate an induced current in the object to be heated 22 according to the law of electromagnetic induction. In the secondary circuit 20, the fluctuating magnetic field that reaches the secondary magnetic core 21 is short-circuited around the secondary magnetic core 21 according to the law of electromagnetic induction, and is arranged in a loop of the conductive heating object 22. Generates an induced current inside. Since the object to be heated 22 has an internal resistance, when an induced current is generated inside the object to be heated 22, Joule heat is applied to the inside of the object to be heated 22.

The material of the object to be heated 22 is not particularly limited as long as it is a conductor, and examples thereof include iron, non-ferrous metals, alloys, and conductive polymers. The shape of the object to be heated 22 may be short-circuited around the secondary magnetic core 21 and can be arranged in a loop shape, such as a ring shape such as a gear, a pipe shape such as a steel pipe, or a cable shape such as a steel wire. Although it is conceivable, its material and shape are not limited to these.

By arranging the ring-shaped, pipe-shaped, or cable-shaped heating object 22 in a loop shape or the like, the heating object 22 is short-circuited to form an electric circuit. Therefore, the fluctuating magnetic field of the secondary magnetic core 21 can generate an induced current in the object to be heated 22 according to the law of electromagnetic induction.

According to the heating device 1 according to the present invention, since it is not necessary to bring the electrode into contact with the object to be heated, there are problems of electrode wear in direct energization heating and various problems caused by electrode wear (increasing running cost, electrode). (Reducing the risk of consumables being mixed in) can be solved.

[Secondary resonance capacitor 23]
The secondary resonance capacitor 23 is electrically connected to the object to be heated 22. The secondary resonance capacitor 23 may have a sufficient capacitance to achieve magnetic field resonance, regardless of its structure or manufacturing method.

According to Non-Patent Document 1 (“Efficiency and Magnetic Flux in Magnetic Resonance Coupling”, Journal of AEM Society of Japan, vol.24, No.4, pp.317-322 (2016)), the resonance frequency of the heating device is ω, and the primary circuit The resistance, inductance, and capacitance of 10 are r ₁ , L ₁ , C ₁ , respectively, and the resistance, inductance, and capacitance of the secondary circuit 20 are r ₂ , L ₂ , C ₂ , respectively, the load is _RL , and the excitation inductance is L _m . Assuming that the coupling coefficient is k, the power transmission efficiency η can be obtained by the equation (1).
^{_{η = (ωL m) 2 R}} L / [{(r 2 + R L) 2 + (ωL 2 -1 / ωC 2) 2} r 1
^{_{+ (ΩL m) 2 r 2}} + (ωL m) 2 R L] ··· (1)

When the load _{R L} is equal to the optimum load _{R Lopt} indicated by equation (2), Equation (1) is an ideal magnetic resonance condition.
^{_{R Lopt = {r 2 2 +}} (r 2 / r 1) (ωL m) 2 + (ωL 2 -1 / ωC 2) 2} 1/2 ··· (2)

At this time, C ₂ , ω, and L ₂ satisfy the equation (3).
C ₂ = 1 / (L ₂ ω ² ) ・ ・ ・ (3)

That is, it is preferable that the secondary resonance capacitor 23 has a capacitance such that the capacitance of the secondary circuit 20 is C ₂ = 1 / (L ₂ ω ² ).

According to the heating device 1 according to the present invention, the secondary resonance capacitor 23 is electrically connected to the heating target 22 of the secondary circuit 20. Since the magnetic field resonance condition can be achieved by the capacitance (capacitance) of the secondary resonance capacitor 23, the heating device 1 according to the present invention can solve the decrease in energy efficiency due to the leakage flux.

[Insulation member 24]
Although not an essential configuration, the secondary circuit 20 preferably includes a heat insulating member 24 arranged around the object to be heated 22. Since the presence of the heat insulating member 24 can prevent the Joule heat generated by the object to be heated 22 from flowing out to the outside of the heat insulating member 24, the outside of the secondary circuit 20 including each member on the primary circuit 10 side. In addition to the members in the above, it is possible to prevent the Joule heat generated by the object to be heated 22 from being wasted in order to heat each member (secondary magnetic core 21 and secondary side resonance capacitor 23) on the secondary circuit 20 side.

The heat insulating member 24 is preferably a material that exhibits transparency to a magnetic field of magnetic field resonance because it can suppress the generation of eddy current that causes energy loss. The material of the heat insulating member 24 is not particularly limited as long as it has heat insulating properties and suppresses the iron loss, and glass wool, ceramic fiber, glass cloth, silica cloth, basalt fiber, rock wool, concrete, alumina cement and the like can be used. Can be mentioned. It is also possible to configure the heat insulating member 24 with a composite member in which the above materials are combined.

[Temperature measuring means 25]
The secondary circuit 20 adjusts the amount of feed to the feed coil 12 based on the temperature measuring means 25 that directly or indirectly measures the temperature of the object to be heated 22 and the temperature measured by the temperature measuring means 25. It is preferable to further provide a power supply amount adjusting means.

According to this heating device 1, the temperature of the object to be heated 22 is directly or indirectly measured, and the current or phase of the power supply source (power supply or the like) that supplies power to the power supply coil 12 is controlled based on the measurement result. Therefore, more efficient power transmission and heat treatment of the heating object 22 can be performed.

The temperature measuring means 25 is not particularly limited as long as it can measure the temperature of the object to be heated 22. Examples of the direct temperature measuring means 25 include a thermocouple, a radiation thermometer, and a combination thereof. Examples of the indirect temperature measuring means 25 include a method of measuring the temperature change of the resistance by using an ammeter electrically connected to the object to be heated 22. However, the temperature measuring means 25 of the present invention is not limited to these.

The temperature measuring means 25 enables heat treatment such as keeping the temperature of the object to be heated 22 below a certain level or within a certain range, and keeping the rate of temperature rise within a certain range. As a result, metal can be annealed, tempered, carburized, and the like.

[Insulation wall 30]
The heating device 1 includes a heat insulating wall 30. The heat insulating wall 30 is configured to surround the secondary circuit 20 so as to separate the primary circuit 10 from the secondary circuit 20.

The heat insulating wall 30 exhibits permeability to the magnetic field of magnetic field resonance. If it does not show transparency to a magnetic field, an eddy current that causes energy loss is generated inside the heat insulating wall 30, which is not preferable.

The heat insulating wall 30 is not particularly limited as long as it is a material that exhibits permeability to a magnetic field of magnetic field resonance, and examples thereof include glass wool, ceramic fiber, glass cloth, silica cloth, basalt fiber, rock wool, concrete, and alumina cement. Be done. It is also possible to configure the heat insulating wall 30 with a composite member in which two or more of these materials are combined. The heat insulating wall 30 configured in this way exhibits transparency to the magnetic field of magnetic field resonance while separating the primary circuit 10 and the secondary circuit 20, so that the primary magnetic core 11 and the secondary magnetic core 12 are exhibited. Magnetic coupling with is not inhibited. The fluctuating magnetic field generated in the primary magnetic core 11 can reach the secondary magnetic core 21 through the magnetic field permeable heat insulating wall 30.

Further, the heat insulating wall 30 is configured to surround the secondary circuit 20. By surrounding the secondary circuit 20 with the heat insulating wall 30, it is possible to prevent the Joule heat generated by the heating object 22 from flowing out to the outside of the secondary circuit 20. Therefore, according to the heating device 1 according to the present invention, the Joule heat generated by the object to be heated 22 is outside the secondary circuit 20 including each member (primary magnetic core 11, power feeding coil 12) on the primary circuit 10 side. It is possible to prevent wasted to heat the entire heating device 1.

The heating device 1 according to the present invention operates by resonating the primary circuit 10 and the secondary circuit 20 with a magnetic field. At this time, since the heat insulating wall 30 that separates the primary circuit 10 and the secondary circuit 20 exhibits permeability to the magnetic field of magnetic field resonance, the magnetic coupling between the primary magnetic core 11 and the secondary magnetic core 21 is hindered. Not done. The fluctuating magnetic field generated in the primary magnetic core 11 can reach the secondary magnetic core 21 through the magnetic field permeable heat insulating wall 30.

<How to use the heating device 1>
Hereinafter, a method of using the heating device 1 according to the present embodiment will be described.

When the power is turned on, the feeding coil 12 of the primary circuit 10 receives an AC current, and then a first magnetic field is generated around the feeding coil 12 by the principle of electromagnetic induction, and the generated first magnetic field magnetizes the primary magnetic core 11. Then, a first magnetic field is generated, and the first magnetic field reaches the secondary magnetic core 21 beyond the heat insulating wall 30 which exhibits permeability to a fluctuating magnetic field, and this first magnetic field magnetizes the secondary magnetic core 21. Then, a fluctuating magnetic field is generated around the secondary magnetic core 21.

This fluctuating magnetic field directly generates an induced current inside the heated object 22 arranged in a loop around the secondary magnetic core 21 by the principle of electromagnetic induction, and the generated induced current is Joule heat inside the heated object 22. Is generated, and the object 22 to be heated is directly heated from the inside.

At this time, due to the presence of the secondary resonance capacitor 23 connected to the object to be heated 22, the primary circuit 10 and the secondary circuit 20 are in a state of magnetic field resonance, and the alternating current received by the feeding coil 12 is the object to be heated. It is transmitted to 22 with much higher efficiency than when it is not magnetic resonance. The Joule heat generated inside the heat-resistant member 22 is used for heating the heat-resistant member 22 without heating the entire secondary circuit 20 due to the presence of the heat-resistant member 24, and Joule flows out to the outside of the heat-resistant member 24. Part of the heat also heats the object to be heated 22 without heating the primary circuit 10 due to the presence of the heat insulating wall 30.

When the heating target 22 is heat-treated within the temperature range defined by the upper limit and the lower limit of the temperature of the heating target 22, the temperature of the heating target 22 approaches the upper limit or reaches the lower limit. The temperature measuring means 25 detects that the vehicle is approaching. When the temperature measuring means 25 detects that the temperature of the object to be heated 22 has approached the upper limit, it adjusts the current or phase of the alternating current supplied to the feeding coil 12 to reduce the transmitted current and heat it. The temperature of the object 22 is kept within the specified temperature range. When the temperature measuring means 25 detects that the temperature of the object to be heated 22 has approached the lower limit, it adjusts the current or phase of the alternating current supplied to the feeding coil 12 to increase the transmitted current and heat it. The temperature of the object 22 is kept within the specified temperature range.

<Heating device 1'according to the first modification of the present embodiment>
FIG. 2 is a schematic schematic diagram for explaining the heating device 1'according to the first modification of the present embodiment. The heating device 1'has the same configuration as the heating device 1 described in the present embodiment, except that the configuration of the secondary circuit 20'is partially different. Hereinafter, the characteristics of the heating device 1'different from those of the heating device 1 shown in FIG. 1 will be described.

[Secondary circuit 20']
In the secondary circuit 20', the object to be heated 22'is not limited to a solid, but may be a liquid or a powder. At this time, the secondary circuit 20'provides a ring-shaped container 24', and the object to be heated 22'is housed inside the ring-shaped container 24'.

[Heating object 22']
The object to be heated 22'is not particularly limited as long as it is a conductive liquid or powder, and is metal powder such as iron powder and copper powder, powder of a conductive polymer such as polyacetylene and polythiophene, and metal conductive such as an aqueous polyvinyl alcohol solution. Examples include aqueous solutions and foods.

[Ring-shaped container 24']
The ring-shaped container 24'is arranged around the secondary magnetic core 21. The ring-shaped container 24'is configured to accommodate a liquid or powder heating object 22'. The material of the ring-shaped container 24'is not particularly limited as long as it can accommodate the object to be heated 22', and examples thereof include glass, alumina porcelain, mullite porcelain, and other ceramics. The ring-shaped container 24'may be heat insulating. Further, the ring-shaped container 24'may be covered with a lid that can be opened and closed.

By accommodating the liquid or powder heating object 22'in the ring-shaped container 24', an electric circuit in which the liquid or powder heating object 22'is short-circuited is formed. Therefore, the fluctuating magnetic field of the secondary magnetic core 21 generates an induced current in the object to be heated 22'according to the law of electromagnetic induction. Since the object to be heated 22'has an internal resistance, when an induced current is generated inside the object to be heated 22', Joule heat is applied to the inside of the object to be heated 22'.

<Heating device 1'' according to the second modification of the present embodiment>
FIG. 3 is a schematic schematic diagram for explaining the heating device 1 ″ according to the second modification of the present embodiment. The heating device 1 ″ will be described in the present embodiment except that the shape of the primary magnetic core 11 ″ in the primary circuit 10 ″ and the shape of the secondary magnetic core 21 ″ in the secondary circuit 20 ″ are different. It has the same configuration as the heating device 1. Hereinafter, the characteristics of the heating device 1'' that are different from those of the heating device 1 shown in FIG. 1 will be described.

[Primary circuit 10'']
The primary circuit 10 ″ includes a primary magnetic core 11 ″.

[Primary magnetic core 11'']
The primary magnetic core 11 ″ in this modification is made of the same material as the primary magnetic core 11, and the magnetic pole area is larger than the cross-sectional area of the feeding coil 12. Since the magnetic pole area of the primary magnetic core 11 ″ is larger than the cross-sectional area of the feeding coil 12, the first magnetic flux loop coming out of the primary magnetic core 11 ″ is reduced.

From the viewpoint of reducing the first magnetic flux loop, it is preferable that the magnetic pole area of the primary magnetic core 11 ″ is larger than the cross-sectional area of the feeding coil 12, and the magnetic pole area of the primary magnetic core 11 ″ is that of the feeding coil 12. It is more preferably twice or more the cross-sectional area, and further preferably three times or more.

On the other hand, since the weight of the primary magnetic core 11 ″ increases significantly with respect to the decrease in the first magnetic flux loop, the upper limit of the magnetic pole area of the primary magnetic core 11 ″ is 100 times or less the cross-sectional area of the feeding coil 12. It is preferable, and it is more preferable that it is 10 times or less.

[Secondary circuit 20'']
The secondary circuit 20 ″ includes a secondary magnetic core 21 ″.

[Secondary magnetic core 21'']
The secondary magnetic core 21 ″ in this modification is made of the same material as the secondary magnetic core 21, and the magnetic pole area is larger than the cross-sectional area of the feeding coil 12. Since the magnetic pole area of the secondary magnetic core 21 ″ is larger than the cross-sectional area of the feeding coil 12, the second magnetic flux loop emitted from the secondary magnetic core 21 ″ is reduced.

From the viewpoint of reducing the second magnetic flux loop, the magnetic pole area of the secondary magnetic core 21 ″ is preferably larger than the cross-sectional area of the feeding coil 12, and the magnetic pole area of the secondary magnetic core 21 ″ is the feeding coil. It is more preferably twice or more the cross-sectional area of 12, and further preferably three times or more.

On the other hand, since the weight of the secondary magnetic core 21 ″ increases significantly with respect to the decrease in the second magnetic flux loop, the upper limit of the magnetic pole area of the secondary magnetic core 21 ″ is 100 times or less the cross-sectional area of the feeding coil 12. It is preferably, and more preferably 10 times or less.

When the magnetic pole shapes of the primary magnetic core 11 ″ and the secondary magnetic core 21 ″ are remarkably asymmetric, the first magnetic flux loop and the second magnetic flux loop increase as compared with the case where the magnetic pole shapes are symmetrical. In order to reduce the first magnetic flux loop and the second magnetic flux loop, the magnetic pole shapes of the primary magnetic core 11 ″ and the secondary magnetic core 21 ″ are preferably symmetrical.

In order to avoid an increase in the first magnetic flux loop and the second magnetic flux loop due to the asymmetric magnetic pole shape, it is preferable that the magnetic pole area of the primary magnetic core 11 ″ and the magnetic pole area of the secondary magnetic core 21 ″ are substantially equal. .. Specifically, the magnetic pole area of the primary magnetic core 11 ″ is preferably 0.7 times or more, more preferably 0.8 times or more the magnetic pole area of the secondary magnetic core 21 ″. It is preferably 0.9 times or more, more preferably 0.95 times or more, and particularly preferably 0.95 times or more.

Further, the magnetic pole area of the primary magnetic core 11 ″ is preferably 1.3 times or less, more preferably 1.2 times or less, the magnetic pole area of the secondary magnetic core 21 ″. .1 times or less is more preferable, and 1.05 times or less is particularly preferable.

In this modification, the reduction of the first magnetic flux loop and the second magnetic flux loop strengthens the magnetic field coupling between the primary magnetic core 11 ″ and the secondary magnetic core 21 ″. Therefore, the coupling coefficient k between the feeding coil 12 on the primary circuit side and the heating target 22 on the secondary circuit side can be brought close to the ideal value of 1, and the feeding efficiency to the heating target 22 can be further improved. Can be enhanced.

Further, the heating device 1 ″ of the present modification can be provided with a ring-shaped container 24 ′ similar to that shown in the first modification. Thereby, as in the case of the first modification, it is possible to heat the object to be heated 22'which is a liquid or powder.

1 Heating device 10 Primary circuit 11, 11'' Primary magnetic core 12 Feed coil 13 Primary side resonance capacitor 16 Variable transformer 20 Secondary circuit 21, 21'' Secondary magnetic core 22, 22'Secondary magnetic core 23, 22'Secondary Side resonance capacitor 24 Insulation member 24'Ring-shaped container 25 Temperature measuring means 30 Insulation wall

Claims (8)

With the primary circuit
The primary circuit and the secondary circuit coupled by magnetic field resonance,
A heat insulating wall that separates the primary circuit and the secondary circuit by surrounding the secondary circuit and exhibits transparency to the magnetic field of the magnetic field resonance.
With
The primary circuit
With the primary magnetic core,
It has a feeding coil arranged around the primary magnetic core and receiving an alternating current having an operating frequency of 400 Hz or less.
The secondary circuit
A secondary magnetic core coupled to the primary magnetic core by magnetic field resonance,
A conductive heating object that is short-circuited around the secondary magnetic core and arranged in a loop.
A heating device having a secondary resonance capacitor that is electrically connected to the object to be heated. The heating device according to claim 1, wherein the primary circuit further includes a primary resonance capacitor that is electrically connected to the feeding coil. The heating device according to claim 1 or 2, wherein the object to be heated is arranged inside a heat insulating member. The heating device according to any one of claims 1 to 3, wherein the object to be heated has a ring shape, a pipe shape, or a cable shape, and the object to be heated is arranged in a loop shape. The secondary circuit further comprises a ring-shaped container.
The object to be heated is a conductive liquid or a conductive powder.
The heating device according to any one of claims 1 to 3, wherein the ring-shaped container is provided in a ring shape around the secondary magnetic core and is configured to accommodate the heating object inside. A temperature measuring means for directly or indirectly measuring the temperature of the object to be heated,
The heating device according to any one of claims 1 to 5, further comprising a feeding amount adjusting means for adjusting the feeding amount to the feeding coil based on the temperature measured by the temperature measuring means. The magnetic pole area of the primary magnetic core is larger than the cross-sectional area of the feeding coil.
The heating device according to any one of claims 1 to 6, wherein the magnetic pole area of the secondary magnetic core is larger than the cross-sectional area of the feeding coil. The heating device according to any one of claims 1 to 7, further comprising a variable transformer electrically connected to the power feeding coil.

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