JP6332853B2 - Induction heating device - Google Patents

Description

  The present invention relates to an induction heating apparatus.

  As an induction heating apparatus, as shown in Patent Document 1, there is an induction heating apparatus in which a temperature detection element is attached to a heated object and the temperature is directly measured.

  However, the operation of attaching the temperature detection element to the heated body is troublesome, and there is a danger in removing the temperature detection element from the heated heated body. Furthermore, when attaching a temperature detection element to a to-be-heated body, the contact state of a temperature detection element and a to-be-heated body differs separately, and it may become an error of detection temperature.

  In addition, although the method of detecting the temperature of a to-be-heated body using non-contact-type temperature detection means, such as a radiation-type thermometer, can also be considered, detection accuracy is low or it influences the surface emissivity (emissivity) of a to-be-heated body. In many cases, accurate temperature detection is difficult.

JP 2002-79559 A

  Accordingly, the present invention has been made in order to solve the above-described problems, and it is a main object of the present invention to eliminate the need for a temperature detection element for measuring the temperature of the object to be heated in the induction heating apparatus.

  That is, the induction heating device according to the present invention includes a power supply circuit that is connected to a winding of a magnetic flux generation mechanism and is provided with a control element that controls an alternating current or an alternating voltage. An induction heating device for induction heating, obtained from an alternating current value obtained from an alternating current detection unit that detects an alternating current flowing through the winding and an alternating voltage detection unit that detects an alternating voltage applied to the winding. An AC voltage value, a power factor obtained from a power factor detection unit that detects a power factor of an induction heating unit including the heated object and the magnetic flux generation mechanism, a winding resistance value of the winding, and the magnetic flux generation The heated object using as parameters the magnetic flux density generated by the mechanism and the excitation resistance value obtained from the relationship between the magnetic flux generation mechanism and the exciting resistance of the magnetic circuit composed of the heated object Characterized in that it comprises a heated body temperature calculating unit for calculating the temperature. As a relational characteristic between the magnetic flux density generated by the magnetic flux generation mechanism and the excitation resistance of the magnetic circuit composed of the heated body and the magnetic flux generation mechanism, those measured in advance can be used. Further, the winding resistance value of the winding may be directly detected by the winding resistance detecting unit provided with a winding resistance detecting unit for detecting the winding resistance of the winding, which will be described later. As described above, a winding temperature detection unit for detecting the winding temperature may be provided, and the winding resistance value may be calculated from the winding temperature obtained from the winding temperature detection unit, or intermittently in the winding. A winding resistance value may be calculated by applying a direct current voltage to the current and detecting a direct current flowing at that time.

  If this is the case, the object to be heated is set with the parameters of the current value of the winding, the voltage value of the winding, the power factor of the induction heating unit, the resistance value of the winding, and the excitation resistance value of the magnetic circuit. Therefore, the temperature of the object to be heated can be calculated without providing a temperature detecting element in the object to be heated.

  Specifically, the heated object temperature calculation unit includes a current value obtained from the current detection unit, a voltage value obtained from the voltage detection unit, a power factor obtained from the power factor detection unit, and the winding. The resistance value of the object to be heated is calculated using the line resistance value and the excitation resistance value obtained from the relational characteristics of the magnetic flux density and the magnetic resistance of the magnetic circuit as parameters, and the resistance value of the object to be heated and the object to be heated are calculated. It is desirable to calculate the temperature of the heated object using the relative permeability of the body.

  More specifically, the induction heating device includes a current value obtained from the current detection unit, a voltage value obtained from the voltage detection unit, and a power factor obtained from the power factor detection unit. An impedance calculation unit for calculating an impedance (hereinafter referred to as a unit impedance), and the impedance calculation unit further uses the unit impedance, the winding resistance value, and the excitation resistance value as parameters. The resistance value is calculated.

Here, FIG. 5 shows an equivalent circuit of an induction heating unit including a heated object and a magnetic flux generation mechanism. When the AC voltage is applied by the power supply circuit, the input AC voltage V applied to the winding is divided by the AC current I flowing through the winding, and multiplied by the power factor cosφ of the induction heating unit. A combined resistance r _comb consisting of r ₁ , excitation resistance r ₀ , and resistance r _{2 of the} object to be heated is calculated. This combined resistance r _comb is expressed by the following equation.
r _comb = (V / I) × cos φ [Ω]
r _comb = (r ₁ r ₂ + r ₁ r ₀ + r ₂ r ₀ ) / (r ₂ + r ₀ ) [Ω]

Rewriting into the equation for obtaining the resistance r _{2 of the} heated object is as follows.
r ₂ = r ₀ (r ₁ −r _comb ) / (r _comb −r ₁ −r ₀ ) [Ω]

In the equation for the resistance r ₂ of the heated object, the excitation resistance r ₀ can be obtained from the relationship with the magnetic flux density generated by the magnetic flux generation mechanism. This relationship is determined by a combination of the shape and thickness of the iron core of the magnetic flux generation mechanism and the material of the object to be heated. FIG. 6 shows the magnetic flux density generated by the magnetic flux generation mechanism when the iron core of the magnetic flux generation mechanism is a directional silicon steel sheet having a thickness of 0.23 mm and the material of the object to be heated is a heat treatment material of carbon steel S45C. The characteristic with excitation resistance is shown.

The magnetic flux density Bm is, when Vm a voltage vector calculation subtracting the voltage drop due to the resistance r ₁ of the reactance l ₁ and winding of the winding from the input AC voltage V, can be calculated by the following equation. In addition, the following formula | equation is a formula in the to-be-heated body which makes | forms a cylinder shape.

l ₁ = [1.975 × D × N ² × κ {d + (a + σ) / 3} / πLh] × 10 ⁻⁹ [H]
Here, D is the average diameter [mm] of the magnetic flux generation mechanism and the current permeation part of the heated object, and when the shape is an n-gon, the value is the average circumference / π. N is the number of turns of the winding, a is the coil thickness [mm], Lh is the winding width [mm], and d is the distance [mm] between the winding and the object to be heated.
Further, σ is the current penetration depth [mm] of the heated body, the specific resistance of the material of the heated body is ρ [μΩ · cm], the relative permeability of the heated body is μs, and the frequency is f [Hz]. Then, σ = {5.03√ (ρ / μs × f)} × 10 [mm].
κ is a Rogowski coefficient and is represented by κ = {1− (a + σ + d) / πLh}.
Vm = √ {(cos φ × V−I × r ₁ ) ² + (sin φ × V−2πf × l ₁ × I) ² } [V]
Bm = Vm × 10 ⁸ /(4.44×f×N×Sm) [G]
Here, Sm is a magnetic path cross-sectional area [cm ² ] of the iron core.

  In the above formula, the relative permeability μs indicates a characteristic change characteristic with the magnetic flux density for each material, and is thus obtained from the change characteristic measured in advance for each material. When the material of the object to be heated is, for example, carbon steel S45C, the relationship between the magnetic flux density and the relative magnetic permeability is as shown in FIG.

  Since the magnetic flux density Bm is not determined at the calculation stage of the above formula, the input AC voltage V is substituted into the formula for obtaining the magnetic flux density Bm, and the relative permeability μs is calculated from the magnetic flux density Bm and the relationship shown in FIG. The current penetration degree σ is calculated. Further, the magnetic flux density Bm is recalculated using this calculation result, and the current permeability σ is recalculated using the relative permeability μs from the relationship of FIG. By repeatedly calculating in this way, each value converges and a determined magnetic flux density Bm is obtained.

And the magnetic flux density Bm, obtains the excitation resistor r ₀ from the relationship between the magnetic flux density Bm and the excitation resistor r ₀ shown in Fig.

In the formula of the resistance r ₂ of the object to be heated, the resistance r ₁ of the winding is determined by the material, length, cross-sectional area and winding temperature of the wire constituting the winding, and as described above, the material of the wire If is, for example, copper, it can be calculated by the following equation.
r ₁ = kL / 100 Sc [Ω]
k = 2.1 (234.5 + θ _C ) /309.5
Here, L is the length of the wire [m], _{S C} is the cross-sectional area of the wire [mm ^2], the theta _C is the temperature of the windings [° C.].

  Specifically, a temperature sensor (temperature detection unit) is embedded in the winding, and the resistance value can be calculated from the temperature of the winding detected by the temperature sensor. Further, as will be described later, the resistance value of the winding can be directly detected by applying a short-time DC voltage to the winding and detecting the direct current flowing at that time.

  A DC voltage application unit that intermittently applies a DC voltage to the winding by controlling a DC power source; a DC voltage applied by the DC voltage application unit; and the winding when the DC voltage is applied. A resistance value calculation unit that calculates a resistance value of the winding from a direct current flowing through the heating element, and the heated object temperature calculation unit uses the resistance value of the winding obtained from the resistance value calculation unit. It is desirable to calculate the temperature of the object to be heated. Specifically, the to-be-heated body temperature calculation unit is configured by the unit impedance obtained by the impedance calculation unit, the winding resistance value obtained by the resistance value calculation unit, and the excitation resistance value of the magnetic circuit. It is desirable to calculate the temperature of the heated object.

When the temperature of the winding that is the primary coil changes due to energization, r ₁ in the equivalent circuit of the single-phase induction heating unit shown in FIG. 5 changes, so that the circuit impedance also changes, that is, r _comb also Will change. Therefore, it is necessary to recalculate the resistance r ₂ of the heated object. However, this change is irrelevant to the change in the temperature of the heat generating part of the heated body, and it is necessary to correct the change.

The resistivity and temperature of the winding have a relationship that is approximately proportional to the absolute temperature, but shows inherent change characteristics depending on the material. If the material is, for example, copper wire, since the relationship of the following equation, the resistance value r ₁ of the winding if the temperature of the winding is known can be calculated.
r ₁ = kL / 100S [Ω]
k = 2.1 (234.5 + θ _C ) /309.5
Here, L is the wire length [m], S is the wire cross-sectional area [mm ² ], and θ _C is the winding temperature [° C.].

Here, considering the case where the winding is outside the heated body, the outer diameter of the heated body is Φ [cm], the current penetration depth is σ [cm], and the inner surface cross-sectional area of the current penetration depth is If S _i [cm ² ] and the heating inner surface length (equal to the winding width) of the heated body is l _S [cm], r ₂ is a primary conversion value viewed from the winding side, so r ₂ is the secondary conversion value as viewed from the heating side, the value obtained by the μΩ the unit When R _2, R ₂ is expressed by the following equation.
R ₂ = (r ₂ / N ² ) × 10 ⁶ [μΩ]
R ₂ = ρπ (Φ−σ) / S _i
S _i = σl _S
Therefore,
R ₂ σl _S = ρπ (Φ−σ)

Here, the current penetration depth σ is expressed by the following equation where the relative permeability is μs and the frequency is f.
σ = 5.03√ (ρ / μs × f) [cm]
Substituting this σ into the above equation,
5.03√ (ρ / μs × f) R ₂ l _S = ρπΦ−5.03ρπ√ (ρ / μs × f)
Divide both sides by 5.03√ (ρ / μs × f)
R ₂ l _S = ρπΦ / {5.03√ (ρ / μs × f)} − ρπ
By transforming this equation,
R ₂ l _S + ρπ = ρπΦ / {5.03√ (ρ / μs × f)}
Square both sides,
(R ₂ l _S ) ² + 2R ₂ l _S ρπ + (ρπ) ²
= (ΡπΦ) ² /(5.03 ² ρ / μs × f)
By transforming this equation,
(5.03R ₂ l _S ) ² + 2 × 5.03 ² R ₂ l _S ρπ + (5.03ρπ) ²
= Ρμs × f (πΦ) ²
Furthermore, by transforming this formula,
(5.03π) ² × ρ ² + {2 × 5.03 ² πR ₂ l _S − (πΦ) ² μs × f} ρ
+ (5.03R ₂ l _S ) ² = 0
Solving this equation gives
ρ = “− {2 × 5.03 ² πR ₂ l _S − (πΦ) ² μs × f}
−√ [{2 × 5.03 ² πR ₂ l _S − (πΦ) ² μs × f} ²
−4 × 5.03 ⁴ (πR ₂ l _S ) ² ] ”/ {2 × (5.03π) ² }
The specific resistance ρ shows a characteristic specific to temperature for each material. For example, in the case of the specific resistance ρ of carbon steel S45C, if the temperature of the heated surface of the heated body is θ _S [° C.], the following equation It becomes.
ρ = 14.3 × (1 + 2.0 × 10 ⁻³ × θ _S ) [μΩ · cm]
By transforming this equation,
ρ = 14.3 + 2.86 × 10 ⁻² × θ _S
delete ρ,
14.3 + 2.86 × 10 ⁻² × θ _S
= “− {2 × 5.03 ² πR ₂ l _S − (πΦ) ² μs × f}
−√ [{2 × 5.03 ² πR ₂ l _S − (πΦ) ² μs × f} ²
−4 × 5.03 ⁴ (πR ₂ l _S ) ² ] ”/ {2 × (5.03π) ² }
Rewriting the equation for theta _S,
θ _S = | − “{2 × 5.03 ² πR ₂ l _S − (πΦ) ² μs × f}
−√ [{2 × 5.03 ² πR ₂ l _S − (πΦ) ² μs × f} ²
−4 × 5.03 ⁴ (πR ₂ l _S ) ² ] ”/ {2 × (5.03π) ² }
−14.3 | / (2.86 × 10 ⁻² ) [° C.]
As described above, the relative magnetic permeability μs shows a unique change characteristic with the magnetic flux density for each material. If the material of the heated object is, for example, carbon steel S45C, the relationship between the magnetic flux density and the relative magnetic permeability is The result is shown in FIG.

When the winding is inside the heated object, the inner diameter of the heated object is φ and R ₂ is calculated as the following equation.
R ₂ = ρπ (Φ + σ) / S _i
At this time, the temperature θ _S [° C.] of the heated surface of the heated body is expressed by the following equation.
θ _S = | “{2 × 5.03 ² πR ₂ l _S + (πΦ) ² μs × f}
−√ [{2 × 5.03 ² πR ₂ l _S + (πΦ) ² μs × f} ²
−4 × 5.03 ⁴ (πR ₂ l _S ) ² ] ”/ {2 × (5.03π) ² }
−14.3 | / (2.86 × 10 ⁻² ) [° C.]

The heated surface of the heated object that faces the winding of the magnetic flux generation mechanism becomes a heat generating portion, but correction is required for calculating the temperature at a location away from the heat generating portion.
The object to be heated has a hollow cylindrical shape in which the area of the heat generating part and the area of the part spaced from the heat generating part are different, and a flat plate shape in which those areas can be regarded as substantially the same. Depending on the case and the case where each side wall is in the shape of a hollow polygonal cylinder having a flat plate shape, a correction formula suitable for each is adopted.

When the object to be heated has a hollow cylindrical shape and the magnetic flux generating mechanism heats the object to be heated from the outer peripheral side or the inner peripheral side, the temperature of the heated object temperature calculation unit is as follows: Calculate the temperature of the calculation surface.
That is, when the temperature difference between the heated surface of the heated object facing the winding and the temperature calculating surface which is a surface for calculating the temperature is θ [° C.], the heated object temperature calculating unit, The temperature of the object to be heated obtained from the impedance and the relational data is corrected using a temperature difference θ obtained using the following equation to calculate the temperature of the temperature calculation surface.
θ = kP / [2π / {ln (d ₂ / d ₁ ) / λ}]
Here, d ₁ is the diameter [m] of the heated surface, d ₂ is the diameter [m] of the temperature calculating surface, and λ is an average temperature between the heated surface and the temperature calculating surface. The thermal conductivity [W / m · ° C.], P is the heat flow rate [W / m], and k is a correction coefficient calculated from the actual measurement value.

  The thermal conductivity λ varies depending on the material and temperature of the object to be heated. For example, the characteristics of temperature and thermal conductivity of carbon steel are shown in FIG. Further, the current penetration degree of the object to be heated is several μm at a high frequency of several tens to several hundreds kHz, but a current penetration degree of several mm to several tens mm is obtained at a medium frequency of 50 to 1000 Hz. For example, carbon steel has a current penetration of about 10 mm at 60 Hz and 500 ° C. That is, since current penetration is deep in medium frequency induction heating, the difference between the temperature of the heat generating portion (temperature of the heated surface) and the temperature of the temperature calculation surface is smaller than that of the high frequency.

  Measure the temperature rise of the heat generation density and the reached temperature under a certain condition, approximate the relationship between the temperature of the temperature calculation surface of the heated object and the impedance, and calculate the temperature calculation surface of the heated object from the impedance using the approximate expression Find the temperature of If the heat generation density changes, the temperature difference θ in the wall thickness t (distance t between the heated surface and the temperature calculation surface) also changes, and if the temperature reached by the temperature calculation surface of the heated object changes, the average temperature changes. Thermal conductivity also changes. If they are calculated using a conversion formula, the temperature of the temperature calculation surface of the object to be heated can be obtained, and the temperature of the temperature calculation surface of the object to be heated can be calculated by impedance.

It is desirable that a jacket chamber in which a gas-liquid two-phase heat medium is enclosed is formed on a side peripheral wall of the object to be heated. The jacket chamber makes the temperature of the heated object uniform by heat transport by the enclosed gas-liquid two-phase heat medium, and the temperature of the temperature calculation surface of the heated object is also made uniform at the same time.
That is, the detection of the temperature of the object to be heated by impedance detects the average temperature of the surface to be heated, so the temperature of the temperature calculation surface of each part of the object to be heated that is made uniform by the jacket chamber depends on the impedance. It can be said that this is equivalent to a value obtained by adding necessary correction to the detected temperature and converting it to the temperature of the temperature calculation surface.

Here, the cross-sectional area between the heated surface and the temperature calculating surface is S [m ² ], and the sum of the cross-sectional areas of the jacket chamber between the heated surface and the temperature calculating surface is S _j [m ^2]. When the distance between the heated surface and the temperature calculation surface is t [m], and the variable indicating the ratio of the function deterioration of the jacket chamber due to the pressure drop of the heat medium accompanying the temperature drop is α, The heated body temperature calculation unit _sets the diameter d _{1 of the} heated surface as d _j1 = d ₁ ± t {1−α (1−S _j / S)}, and sets the diameter d ₂ of the temperature calculated surface to , D _j2 = d ₂ ± t {1-α (1-S _j / S)} is preferably used to correct the temperature of the object to be heated.
D _j1 is the virtual diameter of the heated surface considering the distance (thickness) reduction due to the jacket chamber, and d _j2 is the virtual temperature calculation plane considering the distance (thickness) reduction due to the jacket chamber. Diameter. Further, in the formula of d _j1 , the ± part is negative when d ₁ > d ₂ and is positive when d ₁ <d ₂ . On the other hand, in the formula of d _j2 , the ± part is positive when d ₁ > d ₂ , and is negative when d ₁ <d ₂ .

Let S be the cross-sectional area perpendicular to the central axis of the object to be heated having a hollow cylindrical shape, S _j be the sum of the cross-sectional areas perpendicular to the central axis of the jacket chamber, and the distance between the heated surface and the temperature calculation surface When t, the thermally converted distance t _j is expressed by the following equation.
t _j = α × t (S−S _j ) / S (α> 1)
Here, α is a variable indicating the rate of deterioration of the function of the jacket chamber due to the pressure drop of the heat medium accompanying the temperature drop. The α-θ relationship is determined by the type of heat medium and the impurity concentration in the jacket chamber.

The difference between the distance t and the thermal conversion distance t _j is
t−t _j = t−α × t (S−S _j ) / S
= T {1-α (S−S _j ) / S}
= T {1-α (1-S _j / S)}

Therefore, the virtual diameter d _{j1 of the} heated surface and the virtual diameter d _j2 of the temperature calculation surface, which are thermally converted, are as follows.
d _j1 = d ₁ ± t {1-α (1-S _j / S)}
d _j2 = d ₂ ± t {1-α (1-S _j / S)}
In the formula of d _j1 , the ± part is negative when d ₁ > d ₂ , and is positive when d ₁ <d ₂ . On the other hand, in the formula of d _j2 , the ± part is positive when d ₁ > d ₂ , and is negative when d ₁ <d ₂ .
That is, the calculated distance between the heated surface and the temperature calculation surface is reduced, and the temperature difference θ is reduced, so that the temperature measurement error is also reduced.

When the object to be heated has a flat plate shape and the magnetic flux generating mechanism heats the object to be heated from one side, the temperature calculation unit of the object to be heated calculates the temperature of the temperature calculation surface as follows. calculate.
That is, when the temperature difference between the heated surface of the heated object facing the winding and the temperature calculating surface which is a surface for calculating the temperature is θ [° C.], the heated object temperature calculating unit, The temperature of the object to be heated obtained from the impedance and the relational data is corrected using a temperature difference θ obtained using the following equation to calculate the temperature of the temperature calculation surface.
θ = kQ / (λS / t)
Here, t is a distance [m] between the heated surface and the temperature calculating surface, S is a cross-sectional area [m ² ] between the heated surface and the temperature calculating surface, and λ is the above-mentioned It is the thermal conductivity [W / m · ° C.] of the heated body at the average temperature [° C.] between the heated surface and the temperature calculation surface, and Q is the calorific value [W] of the heated surface, k is a correction coefficient calculated from an actual measurement value.

The to-be-heated body has a hollow n-square cylindrical shape with a height h [m] and n side lengths a ₁ , a ₂ ,..., A _n [m], and the magnetic flux generation mechanism includes: In the case where the object to be heated is induction-heated from the outer peripheral side or the inner peripheral side, the heated object temperature calculation unit calculates the temperature of the temperature calculation surface as follows. The following shows a case where the distance between the heated surface and the temperature calculation surface is the same in each side wall.

That is, the temperature difference between the heated surface of the heated object facing the winding and the temperature calculating surface which is a surface for calculating the temperature is θ [° C.], and the heated surface on each side of the heated object When the distance between the temperature calculation surfaces is t [m], the heated object temperature calculation unit calculates the temperature of the heated object obtained from the impedance and the relational data as follows: The temperature of the temperature calculation surface is calculated by correcting using the temperature difference θ obtained by using.
θ = kQ / λ [{(a ₁ + a ₂ +... + a _n ) h / t} + m _n × n × h]
Here, n is a natural number starting from 1, and λ is the thermal conductivity [W / m · ° C.] of the heated object at an average temperature [° C.] between the heated surface and the temperature calculating surface, Q is the calorific value [W] of the surface to be heated, k is a correction coefficient calculated from actual measurement values, and _mn is a constant at n.

In the case where a jacket chamber in which a gas-liquid two-phase heat medium is enclosed is formed in the thickness of the heated object having a flat plate shape or a hollow n-square tube shape as described above, the heated surface and the The cross-sectional area between the temperature calculation surfaces is S [m ² ], the sum of the cross-sectional areas of the jacket chamber between the heated surface and the temperature calculation surface is S _j [m ² ], and the heat medium accompanying the temperature decrease When the variable indicating the rate of reduction in the function of the jacket chamber due to the pressure drop is α, the heated object temperature calculation unit sets the distance t between the heated surface and the temperature calculation surface to t _j = αt It is desirable to correct the temperature of the object to be heated using the temperature difference θ obtained as (S−S _j ) / S.

  On the other hand, in the object to be heated having the above-described hollow n-square tube shape, when the distance between the surface to be heated and the temperature calculation surface of each side wall portion is different, the temperature of the object to be heated is calculated as follows. Calculate the temperature of the calculation surface.

That is, the temperature difference between the heated surface of the heated body facing the winding of each side wall portion of the heated body and the temperature calculation surface that is a surface for calculating the temperature is θ _n [° C.], and When the distance between the heated surface and the temperature calculation surface of each side wall portion of the heated object is t ₁ , t ₂ ,... T _n [m], the heated object temperature calculating unit is Then, the temperature of the object to be heated obtained from the impedance and the relational data is corrected using a temperature difference θ _n obtained using the following equation to calculate the temperature of the temperature calculation surface.
_{θ n = k n Q n /} (λ n S n / t n)
Here, t _n is the distance between the heated surface and the temperature calculated surface at the n-th sidewall part [m], S _n is the heated surface and the temperature calculated surface at the n-th sidewall part the cross-sectional area [m ^2] between, lambda _n is n th said at side wall portions of the heated surface and thermal conductivity of the object to be heated at an average temperature [℃] between the temperature calculated surface [W / m a · ° C.], Q _n is the heat value of the heated surface of the n-th sidewall part [W], k _n is a correction coefficient calculated from the measured value.

At this time, in the case where a jacket chamber in which a gas-liquid two-phase heat medium is sealed is formed within the thickness of the heated body, the heated surface and the temperature calculating surface of the nth side wall portion. When the sum of the cross-sectional areas of the jacket chamber is S _nj [m ² ], and the variable indicating the rate of decrease in the function of the jacket chamber due to the pressure drop of the heat medium accompanying the temperature drop is α, the temperature of the heated object The calculation unit calculates a temperature difference θ _n obtained by setting the distance t _n between the heated surface and the temperature calculation surface in the n th side wall as t _nj = αt _n (S _n −S _nj ) / S _n. It is desirable to correct the temperature of the object to be heated.

  When the control element is a semiconductor, the waveform shape of the voltage and current changes depending on the energization angle, but it changes to a different shape, so that the voltage of the excitation impedance changes by changing the shared voltage of each impedance. Thus, the magnetic flux density changes, and the excitation impedance and relative permeability also change. At this time, if the control element, the energization angle, and the load are determined, the voltage and the current each have a fixed shape, and thus the correction coefficient according to the energization angle is determined.

  Here, an impedance correction unit that corrects the impedance obtained by the impedance calculation unit based on an energization angle of the control element is further provided, and the heated object temperature calculation unit includes the corrected impedance corrected by the impedance correction unit and It is desirable to calculate the temperature of the object to be heated from the relation data.

When the control element is a thyristor and the object to be heated (cylindrical metal kettle with outer diameter Φ x depth L x side wall thickness t) is equivalent due to a change in harmonic components due to waveform distortion The voltage applied to the reactance components l ₁ and l ₂ in the circuit will change. Therefore, the voltage applied to the excitation impedance changes and the magnetic flux density also changes. That is, since the excitation impedance and the relative permeability change depending on the magnetic flux density, it is necessary to correct the influence.
Correction impedance R ₂ obtained by correcting the influence of the phase angle change of the thyristor becomes below.
R ₂ = a × R _X
Here, if C = V / V _in ,
^{_{a = a n C n + a}} n-1 C n-1 + a n-2 C n-2 +, ···, + a 2 C 2 + a 1 C + a 0
Here, a _n is a coefficient based on the measured value determined by the induction heating device, a ₀ is a constant.
Also, R _X is a correction before the impedance, V _in is the receiving voltage of the thyristor, V is an output voltage of the thyristor.

  The winding resistance value can be calculated by applying a constant DC voltage to the winding in a short time within a few seconds and dividing the DC voltage by the DC current flowing through the winding. Here, since there is no inductive action in the case of a DC voltage, the DC current is not affected by the heated object, and has only a relationship with the winding resistance value. Since the winding temperature does not change abruptly, even if periodic and short-time measurement values are used, no large measurement error is produced.

  Further, intermittent application of the DC voltage means that the application time within a few seconds is performed at a constant period of several seconds to several tens of minutes, for example. With such intermittent application, it is possible to reduce the demagnetizing action received from the DC component and to minimize the influence on the AC circuit for induction heating. Further, the winding of the induction heating device generally has a large thermal inertia, and the change in the temperature of the winding does not become a large value in the operation under a normal constant load condition. Therefore, if temperature detection performed by a short application time within several seconds is performed in units of several seconds to several tens of minutes, preferably in units of several tens of seconds to several minutes, it is sufficient for temperature control of the object to be heated. I can say that.

  The resistance value calculation unit applies a DC voltage to the winding and calculates a winding resistance value in a state where the AC current or the AC voltage is cut off or minimized by a control element provided in the power supply circuit. It is desirable to be a thing.

  In order to detect only the DC component (DC current) from the current in which the AC current and DC current are superimposed by applying DC voltage to the winding to which AC voltage is applied, a complicated detection circuit is required. End up. Here, the normal induction heating apparatus includes a power supply circuit having a control circuit unit such as a control element for controlling an alternating current or an alternating voltage for controlling the temperature of the object to be heated. For this reason, if the AC current or the AC voltage is cut off or set to a minimum value only during the application time for applying the DC voltage by the control element, the influence of the AC current (AC component) can be suppressed. Component) can be easily detected. Here, the interruption or the minimum value of the AC current or AC voltage is a short time within a few seconds, and is a time interval of several seconds to several tens of minutes, and does not hinder the induction heating action.

  As an embodiment in which the alternating current or the alternating voltage is cut off or set to a minimum value, when the control element has a switch device such as an electromagnetic contactor, the switch device is cut off, or the control circuit unit has, for example, In the case where a semiconductor element (power control element) such as a thyristor is included, a mode in which the energization phase angle of the semiconductor element is minimized can be considered.

In order to accurately calculate the temperature of the temperature calculation surface of the heated object in the temperature rising transition period or the temperature falling transition period of the heated object, the heated object temperature calculation unit calculates the temperature of the heated surface. The calculated value of the temperature calculation surface in a steady state is calculated from the temperature of the heated surface, and the temperature calculation surface reaches the calculated value after ΔT [h] time obtained using the following equation: In addition, it is desirable to calculate the temperature of the temperature calculation surface in the transition period.
ΔT = k × w × c × t ² / (2λ) [h]
Here, w is the specific gravity [kg / m ³ ] of the material of the heated object, c is the specific heat [kcal / kg · ° C.] of the material of the heated object, and t is the heated surface and the The distance [m] between the temperature calculation surfaces, λ is the thermal conductivity [kcal / m · h · ° C.] of the material of the object to be heated, and k is a correction coefficient obtained from the measured value.

  FIG. 9 shows the temperature change of the heated object during the temperature rising transition period, and FIG. 10 shows the temperature change of the heated object during the temperature falling transient period. 9 and 10, the solid line indicates the heated surface temperature of the heated object, the dotted line indicates the calculated value of the temperature calculation surface when the steady state calculated from the heated surface temperature is reached, and the alternate long and short dash line is: The temperature on the temperature calculation surface in the transition period is shown.

Temperature of the temperature calculating surface in the transition period is lower than the temperature of the temperature calculation surface when reaching a steady state, at the time of Atsushi Nobori, after [Delta] T time (T n ₊ [Delta] T), steady-state calculated at the time T _n The temperature of the temperature calculation surface will reach the calculated value of the temperature calculation surface at the time, and when the temperature falls, the temperature of the temperature calculation surface is calculated at the time T _n before ΔT time (T _n −ΔT). This is the calculated value of the temperature calculation surface in the steady state.

Therefore, it is necessary to calculate the temperature of the temperature calculation surfaces divided in a time and during cooling heating, the heated surface temperature θ _{i (n)} at time T _n is time T _(n-1) i.e. ΔT time Compared with the previous heated surface temperature θ _{i (n−1)} , it is determined whether the temperature is in a temperature rising transient period or a temperature falling transient period. That is, if θ _{i (n)} > θ _{i (n−1)} , it is a temperature rising transient period, and if θ _{i (n)} <θ _{i (n−1)} , it is a temperature falling transient period.
The time period to be compared is determined to be a value that does not pose a problem for control depending on the thickness of the object to be heated and the heating capacity held, but it is several milliseconds to several tens of seconds, preferably several hundred milliseconds to several seconds. Value.

_{θ i (n)> θ i} (n-1), that is, the temperature calculation when heated transition time that is calculated from the heated surface temperature Tn when θ _{i (n),} leading to a steady state at that time Assuming that the surface temperature is θ _n , the actual temperature calculation surface temperature in the temperature rising transition period reaches the temperature θ _n at T _{(n + 1)} after ΔT time has elapsed from T _n .
Here, since T _{(n + 1)} −T _n = ΔT, if the temperature θ _n is displayed when the time ΔT has elapsed, it is equivalent to displaying the temperature of the temperature calculation surface at that time. Become.

θ _{i (n)} <θ _{i (n−1)} , that is, the temperature calculation when the temperature reaches the steady state at that time, calculated from the heated surface temperature θ _{i (n)} at the time T _{n in the} temperature-falling transition period Assuming that the surface temperature is θ _n , the actual temperature calculation surface temperature during the temperature-falling transition period has reached the temperature θ _n at T _(n−1) before ΔT time from T _n . That is, the temperature of the temperature calculation plane is at T _n time has become a temperature lower than the theta _n, accurate temperature calculation is difficult. Accordingly, as an approximate value, if the temperature is displayed assuming that the temperature has decreased by θ _{i (n−1)} −θ _in , the value does not deviate greatly. That is, the temperature θ _{E on} the temperature calculation surface is expressed by the following equation.
θ _E ≈θ _n − {θ _{i (n−1)} −θ _in }

  The temperature of the temperature calculation surface in the transition period will eventually converge to the steady state calculated temperature if the induction heating device is in steady operation. In principle, it is unlikely to operate for product production when the temperature of the object to be heated is raised or lowered, so it is sufficient if the temperature of the temperature calculation surface of the object to be heated can be grasped as an approximate value.

  According to the present invention configured as described above, the temperature of the heated object can be calculated without providing the temperature detecting element in the heated object.

The figure which shows typically the structure of the induction heating apparatus which concerns on 1st Embodiment. Sectional drawing which shows the structure of the induction heating unit of the embodiment typically. The function block diagram of the control apparatus of the embodiment. The figure which shows the temperature calculation flow of the embodiment. The figure which shows the equivalent circuit of a single phase induction heating unit. The characteristic graph which shows the relationship between the magnetic flux density of the magnetic circuit comprised from the to-be-heated body consisting of carbon steel (S45C), and the iron core consisting of a directional silicon steel plate, and exciting resistance. The characteristic graph which shows the relationship between the magnetic flux density and relative permeability of carbon steel (S45C). The characteristic graph which shows the relationship between the temperature of carbon steel (S45C), and thermal conductivity. The figure which shows the temperature change characteristic of the to-be-heated body in a temperature rising transition period. The figure which shows the temperature change characteristic of the to-be-heated body in a temperature fall transition period. Sectional drawing which shows typically the structure of the induction heating unit which concerns on 2nd Embodiment. Sectional drawing which shows typically the structure of the induction heating unit which concerns on 3rd Embodiment. Sectional drawing which shows typically the structure of the induction heating unit which concerns on 4th Embodiment. The figure which shows typically the structure of the induction heating roller apparatus which concerns on deformation | transformation embodiment. The function block diagram of the control apparatus of the embodiment.

<First Embodiment>
A first embodiment of an induction heating apparatus according to the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, the induction heating apparatus 100 according to this embodiment includes a heated body 2 that is heated to heat-treat a processing target, an iron core 31 and a winding for induction heating the heated body 2. A magnetic flux generation mechanism 3 composed of a wire 32 and a power supply circuit 5 connected to the winding 32 and provided with a control element 4 for controlling current or voltage are provided.

  As shown in FIG. 2, the heated body 2 of the present embodiment has a housing portion that houses the object to be processed, and has a height of h [m], an outer diameter of φ [m], and a side wall portion. It is a metal pot having a hollow cylindrical shape with a thickness of t [m]. A plurality of jacket chambers 2S in which a gas-liquid two-phase heat medium is enclosed are formed at equal intervals in the circumferential direction along the central axis in the wall thickness of the side peripheral wall of the body 2 to be heated.

  In addition, the winding wire 32 of the present embodiment has a substantially cylindrical shape that is wound around the outer peripheral surface of the heated body 2 having a hollow cylindrical shape. Thereby, the outer peripheral surface of the heated body 2 becomes a heated surface 2 h that is heated to face the winding 32.

  Furthermore, the control element 4 of this embodiment controls the conduction angle of an alternating current or an alternating voltage with a semiconductor, and is specifically a thyristor.

  And the control apparatus 6 which controls the induction heating roller apparatus 100 of this embodiment is the alternating current value which flows through the winding 32, the alternating voltage value applied to the winding 32, the to-be-heated body 2, and magnetic flux generation mechanism ( The power factor of the induction heating unit 200 composed of the winding 32), the winding resistance value of the winding 32, and the excitation resistance value of the magnetic circuit composed of the heated body 2 and the magnetic flux generation mechanism (winding 32). As a parameter, it has a temperature calculation function for calculating the temperature of the temperature calculation surface 2x of the body 2 to be heated. The temperature calculation surface 2x of the present embodiment is a surface for calculating the temperature separated from the heated surface 2h in the thickness direction at the side wall portion of the heated body 2, and specifically, the inner peripheral surface of the heated body 2 It is.

  Specifically, the control device 6 is a dedicated or general-purpose computer including a CPU, an internal memory, an A / D converter, a D / A converter, an input / output interface, and the like. The control device 6 is configured according to a predetermined program stored in the internal memory. When the CPU and peripheral devices operate, as shown in FIG. 3, an impedance calculation unit 61, an impedance correction unit 62, a temperature calculation data storage unit 63, a heated body temperature calculation unit 64, and a heated body temperature control unit 65. Demonstrate the function as such.

  Hereinafter, each part will be described with reference to the temperature calculation flowchart of FIG. 4 together with FIG. 3.

The impedance calculation unit 61 is obtained from the AC voltage value obtained from the AC current detection unit 7 that detects the AC current I flowing through the winding 32 and the AC voltage detection unit 8 that detects the AC voltage V applied to the winding 32. The impedance (unit impedance) Z ₁ (= V × cos φ / I = r _comb ) of the induction heating unit 200 is calculated from the AC voltage value obtained and the power factor obtained from the power factor detection unit 10 ((FIG. 4 ( 1)).

Furthermore, the impedance calculation unit 61 measures in advance the impedance r _comb and the winding resistance r ₁ obtained from the winding temperature θ _C [° C.] obtained from the temperature detection unit 9 that detects the temperature of the winding 32. The resistance (heated body impedance) r _{2 of the} heated body ₂ is calculated from the exciting resistance r ₀ obtained from the relational characteristic of the magnetic flux density and the magnetic resistance of the magnetic circuit (see FIG. 6) ((2 in FIG. 4). )). The temperature detection unit 9 is embedded in the winding 32.

Specifically, the impedance calculation unit 61 calculates the winding resistance r ₁ by the following formula, and calculates the resistance r ₂ of the heated body 2.
r ₁ = kL / 100S [Ω]
k = 2.1 (234.5 + θ _C ) /309.5
Here, L is the wire length [m], S is the wire cross-sectional area [mm ² ], and θ _C is the winding temperature [° C.].

The impedance calculation unit 61 converts the resistance r ₂ of the object to be heated 2, the secondary-converted value as viewed from the heated body 2 side. When the resistance of the heated body 2 in units of μΩ in terms of secondary is R ₂ and the number of windings is N, the following equation is obtained.
R ₂ = (r ₂ / N ² ) × 10 ⁶

The impedance correction unit 62 corrects the second-order converted resistance R ₂ of the heated body 2 by the energization angle (phase angle) of the control element (thyristor) 4 ((3) in FIG. 4).
Specifically impedance correction unit 62, according to the following equation to correct the impedance R _2.
R ₂ = a × R _X
Here, if C = V / V _in ,
^{_{a = a n C n + a}} n-1 C n-1 + a n-2 C n-2 +, ···, + a 2 C 2 + a 1 C + a 0
Here, a _n is a coefficient based on the measured value determined by the induction heating device, a ₀ is a constant.
Also, R _X is a correction before the impedance, V _in is the receiving voltage of the thyristor, V is an output voltage of the thyristor.

  The temperature calculation data storage unit 63 stores temperature calculation data necessary for calculating the temperature of the heated surface 2 h of the heated body 2. Specifically, the temperature calculation data includes (a) magnetic flux density-excitation resistance relationship data indicating the relationship between the magnetic flux density of the magnetic circuit and the excitation resistance in the induction heating unit, and (b) magnetic flux density and specific permeability measured for each material. It is data including magnetic flux density-relative permeability relationship data indicating the relationship with magnetic permeability (see FIG. 6).

  The heated object temperature calculation unit 64 uses the corrected impedance corrected by the impedance correction unit 62 and the temperature calculation data stored in the temperature calculation data storage unit 63 to be heated on the heated surface of the heated object 2. The temperature for 2 h is calculated ((4) in FIG. 4).

Specifically, the heated body temperature calculation unit 64 calculates the temperature θ _S of the heated surface 2h of the heated body 2 using the following formula.
θ _S = | − “{2 × 5.03 ² πR ₂ l _S − (πΦ) ² μs × f}
−√ [{2 × 5.03 ² πR ₂ l _S − (πΦ) ² μs × f} ²
−4 × 5.03 ⁴ (πR ₂ l _S ) ² ] ”/ {2 × (5.03π) ² }
−14.3 | / (2.86 × 10 ⁻² ) [° C.]

At this time, the heated object temperature calculation section 64, in Formula temperature theta _S above the heated surface 2h, calculated by the following equation R _2.
r ₂ = r ₀ (r ₁ -r _comb ) / (r _comb -r ₁ -r ₀ )
R ₂ = (r ₂ / N ² ) × 10 ⁶

Here, since the combined resistance r _comb is represented by r _comb = (V / I) × cos φ, the AC voltage value obtained by the AC voltage detector 8 and the AC current value obtained by the AC current detector 7 are used. And the power factor obtained by the power factor detection unit 10, the winding resistance value obtained by the resistance detection unit or the winding resistance value obtained from the winding temperature of the temperature detection unit 9, the magnetic flux density and the magnetic circuit It is calculated by the excitation resistance value obtained from the relational characteristic of the excitation resistance.

Exciting resistor r ₀ is the magnetic flux density shows the relation between the magnetic flux density Bm of the magnetic circuit and the excitation resistor r ₀ in the induction heating unit 200 - obtained from the excitation resistor relationship data. Specifically, the magnetic flux density Bm of the body to be heated 2 is calculated by the following formula, and the exciting resistance r ₀ is obtained from the obtained magnetic flux density Bm and the magnetic flux density-exciting resistance relation data.
Bm = Vm × 10 ⁸ /(4.44×f×N×Sm) [G]
Here, Vm is a vector-calculated voltage value [V] obtained by subtracting the voltage drop due to the reactance l ₁ of the winding 32 and the resistance r ₁ of the winding 32 from the input AC voltage V. f is the frequency [Hz], N is the number of turns of the winding 32, and Sm is the magnetic path cross-sectional area [cm ³ ] of the iron core 31.

Resistance r ₁ of the winding 32, the material of the wires forming the windings 32, the length, determined by the temperature of the cross-sectional area and winding, if the material of the wire is, for example, copper, can be calculated by the following formula .
r ₁ = kL / 100 Sc [Ω]
k = 2.1 (234.5 + θ _C ) /309.5
Here, L is the length of the wire [m], _{S C} is the cross-sectional area of the wire [mm ^2], the theta _C is the temperature of the windings [° C.].

Thus, by calculating the combined resistance r _comb , the excitation resistance r ₀ , and the winding resistance r ₁ , the resistance r ₂ of the heated body 2 is calculated, and further the secondary conversion as viewed from the heated body 2 side. R ₂ with the unit of μΩ can be calculated.
can do.

  Further, the heated object temperature calculation unit 64 includes the relative permeability-magnetic flux density relationship data indicating the relationship between the relative permeability and the magnetic flux density shown in FIG. 7, and the magnetic flux density (value determined by the specification) of the heated object 2. From this, the relative permeability μs is obtained.

And the to-be-heated body temperature calculation part 64 substitutes resistance R2 of the to-be-heated body ₂ and relative permeability (micro | micron | mu) s which were calculated | required by the above into the said Formula, and is the temperature (theta) _S of the to-be-heated surface 2h of the to-be-heated body 2. Is calculated.

Specifically, the heated body temperature calculation unit 64 is a temperature between the temperature θ _S of the heated surface 2h of the heated body 2 and the temperature of the temperature calculating surface 2x that is a surface that calculates the temperature separated from the heated surface 2h. When the difference is θ [° C.], the temperature difference θ calculated from the following equation is used to correct the temperature θ _S of the heated surface 2 h to calculate the temperature of the temperature calculation surface 2 x (FIG. 4 ( 5)).
θ = kP / [2π / {ln (d ₂ / d ₁ ) / λ}]
Here, d ₁ is the diameter [m] of the heated surface 2h, d ₂ is the diameter [m] of the temperature calculating surface 2x, and λ is an average temperature between the heated surface 2h and the temperature calculating surface 2x. The thermal conductivity [W / m · ° C.], P is the heat flow rate [W / m], and k is a correction coefficient calculated from the actual measurement value. Here, the heat flow rate P [W / m] is a value obtained by dividing the heat generation amount [W] of the outer surface of the heated body 2 by the heat generation outer surface length [m] (equal to the winding width). m], the to-be-heated body temperature calculation unit 64 uses power values obtained by calculating from the measured values of the current detection unit 7, the voltage detection unit 8, and the power factor detection unit 10. That is, when the power of the induction heating unit and P, and P = I × V × cosφ and the value obtained by subtracting a coil power P _C and the core loss P _f from the unit power P is heated body 2 power P _S Become.

Here, the coil power P _C is P _C = r ₁ × (kI) ² (k is an additional constant for the eddy current generated in the electric wire and is a value determined by the shape of the winding and the electric wire). There, iron loss _{P f becomes P f = {(Vm / r} 0) 2} × r 0/2 = Vm 2 / (2 × r 0). Half and half in the calculation of the core loss P _f, are you 1/2 by multiplying the excitation resistance to the square of the exciting current, and a core loss in core loss and the body to be heated 2 of the iron core 31 of the magnetic flux generating mechanism 3 It is because it is calculating as.
That is, the power P _S of the object to be heated 2 can be expressed as the following formula.
P _S = P−P _C −P _f
= I × V × cos φ−r ₁ × (kI) ² −Vm ² / (2 × r ₀ )

  The heated body temperature calculation unit 64 calculates the temperature of the temperature calculation surface 2x of the heated body 2 in consideration of the thickness reduction due to the jacket chamber 2S formed in the heated body 2.

Specifically, the to-be-heated body temperature calculation unit 64 sets S [m ² ] as the cross-sectional area between the heated surface 2h and the temperature calculating surface 2x, and cuts the jacket chamber between the heated surface 2h and the temperature calculating surface 2x. The sum of the areas is S _j [m ² ], the distance between the heated surface 2h and the temperature calculation surface 2x is t [m], and the rate of decrease in the function of the jacket chamber due to the pressure drop of the heat medium accompanying the temperature drop is When the variable shown is α, the diameter d ₁ of the heated surface 2h is assumed to be a virtual diameter d _j1 (= d ₁ −t {1−α (1−S _j / S)}) in consideration of the thickness reduction. And the diameter d ₂ of the temperature calculation surface 2x is a virtual diameter d _j2 (= d ₂ + t {1−α (1−S _j / S)}) in consideration of the thickness reduction, The temperature calculation of the heated body 2 is performed by correcting the temperature of the heated surface 2h of the heated body 2 using the temperature difference θ obtained from To calculate the temperature of the surface 2x.

  Based on the temperature of the temperature calculation surface 2x of the heated object 2 obtained by the heated object temperature calculating unit 64 as described above, the heated object temperature control unit 65 controls the control element 4 of the power supply circuit, The temperature of the temperature calculation surface 2x of the heated body 2 is controlled to be a predetermined set temperature.

  According to the induction heating apparatus 100 of the present embodiment configured as described above, the alternating current value of the winding 32, the alternating voltage value of the winding 32, the power factor of the induction heating unit 200, and the winding of the winding 32. Since it has the to-be-heated body temperature calculation part 64 which calculates the temperature of the to-be-heated body 2 using a resistance value and the exciting resistance value of the magnetic circuit comprised from the to-be-heated body 2 and a magnetic flux generation mechanism (winding 32) as a parameter. The temperature of the heated body 2 can be calculated without providing the temperature detection element in the heated body 2.

  Further, since the impedance obtained by the impedance calculation unit 61 is corrected by the impedance correction unit 62 using the energization angle of the thyristor 4, the temperature of the heated object 2 can be calculated with high accuracy.

  Further, the heated object temperature calculation unit 64 calculates the temperature of the temperature calculation surface 2x based on the temperature difference θ between the temperature of the heated surface 2h of the heated object 2 and the temperature of the temperature calculation surface 2x. The temperature of the temperature calculation surface 2x of the heating body 2 can be calculated with high accuracy. In addition, the temperature arrival time delay in the transition period during the temperature rise and fall is also calculated and corrected by the heated object temperature calculation unit 64, so that the temperature of the temperature calculation surface 2x of the heated object 2 can be calculated with high accuracy. .

Second Embodiment
Next, a second embodiment according to the present invention will be described. The induction heating apparatus according to the second embodiment is different from the first embodiment in the configuration of the heated body 2 and the function of the heated body temperature calculation unit 64.

  As shown in FIG. 11, the heated body 2 according to the second embodiment has a flat plate shape with a thickness t [m], which is a working surface in which one surface (upper surface in FIG. 11) acts on the object to be processed. It is a metal heating plate. A plurality of jacket chambers 2S in which a gas-liquid two-phase heat medium is enclosed are formed in a lattice shape within the thickness of the heated body 2.

  The winding 32 has a substantially flat plate shape provided on the other surface (the lower surface in FIG. 11) of the heated body 2 so as to be separated from the other surface. Thereby, the other surface of the to-be-heated body 2 becomes the to-be-heated surface 2h heated with the winding 32, and the winding 32 which is a magnetic flux generation mechanism becomes the structure which induction-heats the to-be-heated body 2 from one side.

And the to-be-heated body temperature calculation part 64 is a surface which calculates the temperature separated from the to-be-heated surface 2h in the thickness direction, and the temperature of the to-be-heated surface 2h calculated | required similarly to the said embodiment. When the temperature difference with a certain temperature calculation surface 2x (for example, the temperature of the working surface which is the upper surface) is θ [° C.], the temperature difference of the heated surface 2h is corrected using the temperature difference θ obtained from the following equation. To calculate the temperature of the temperature calculation surface 2x.
θ = kQ / (λS / t)
Here, t is the distance [m] between the heated surface 2h and the temperature calculating surface 2x, S is the cross-sectional area [m ² ] between the heated surface 2h and the temperature calculating surface 2x, and λ is the covered surface. The thermal conductivity [W / m · ° C.] of the heated body at the average temperature [° C.] between the heating surface 2h and the temperature calculation surface 2x, and Q is the calorific value [W] of the heated surface 2h. Yes, k is a correction coefficient calculated from actual measurement values.

  The heated body temperature calculation unit 64 calculates the temperature of the temperature calculation surface 2x of the heated body 2 in consideration of the thickness reduction due to the jacket chamber 2S formed in the heated body 2.

Specifically, the to-be-heated body temperature calculation unit 64 sets S [m ² ] as the cross-sectional area between the heated surface 2h and the temperature calculating surface 2x, and cuts the jacket chamber between the heated surface 2h and the temperature calculating surface 2x. When the sum of the areas is S _j [m ² ], and the variable indicating the rate of reduction in the function of the jacket chamber due to the pressure drop of the heat medium accompanying the temperature drop is α, the space between the heated surface 2h and the temperature calculation surface 2x Is used as a virtual distance t _j (= αt (S−S _j ) / S) in consideration of the thickness reduction, using the temperature difference θ obtained from the above temperature difference θ formula, By correcting the temperature of the heated surface 2h, the temperature of the temperature calculating surface 2x of the heated body 2 is calculated.

<Third Embodiment>
Next, a third embodiment according to the present invention will be described. The induction heating apparatus according to the third embodiment is different from the first and second embodiments in the configuration of the heated body 2 and the function of the heated body temperature calculation unit 64.

As shown in FIG. 12, the heated object 2 according to the third embodiment has a housing part that houses the processing object or a passage part through which the processing object passes, and the height is h [m], _a 1 length of n sides, _{respectively,} a 2, a metallic cylindrical body forming the (hollow square tubular shape in FIG. 12) hollow n rectangular tube shape ··· _a n [m]. A plurality of jacket chambers 2S in which a gas-liquid two-phase heat medium is enclosed are formed at equal intervals in the circumferential direction along the central axis in the wall thickness of the side peripheral wall of the body 2 to be heated.

  In addition, the winding wire 32 of the present embodiment has a substantially hollow n-square tube shape that is wound around the outer peripheral surface of the heated body 2 having a hollow n-square tube shape. Thereby, the outer peripheral surface of the heated body 2 becomes the heated surface 2h heated by the winding 32.

And the to-be-heated body temperature calculation part 64 is a temperature calculation surface which is a surface which calculates the temperature of the to-be-heated surface 2h of the to-be-heated body 2 calculated | required similarly to the said embodiment, and the temperature away from the said to-be-heated surface 2h. When the temperature difference from 2x is θ [° C.], the temperature of the heated surface 2h is corrected using the temperature difference θ obtained from the following equation to calculate the temperature of the temperature calculation surface 2x. In the third embodiment, the distance in the thickness direction between the heated surface 2h and the temperature calculation surface 2x is the same in each side wall portion.
θ = kQ / λ [{(a ₁ + a ₂ +... + a _n ) h / t} + m _n × n × h]
Here, n is a natural number starting from 1, λ is the thermal conductivity [W / m · ° C.] of the heated body at the average temperature [° C.] between the heated surface 2h and the temperature calculation surface 2x, and Q Is the calorific value [W] of the heated surface 2h, k is a correction coefficient calculated from the actual measurement value, and _mn is a constant at n. For example, when n = 4, k ₄ = 0.54.

  The heated body temperature calculation unit 64 calculates the temperature of the temperature calculation surface 2x of the heated body 2 in consideration of the thickness reduction due to the jacket chamber 2S formed in the heated body 2.

Specifically, the to-be-heated body temperature calculation unit 64 sets S [m ² ] as a cross-sectional area between the heated surface 2h and the temperature calculating surface 2x, and a jacket between the heated surface 2h and the temperature calculating surface 2x. When the sum of the cross-sectional areas of the chamber is S _j [m ² ], and the variable indicating the rate of function deterioration of the jacket chamber due to the pressure drop of the heat medium accompanying the temperature drop is α, the heated surface 2h and the temperature calculation surface The distance t between 2x is defined as a virtual distance t _j (= αt (S−S _j ) / S) in consideration of the thickness reduction, using the temperature difference θ obtained from the above temperature difference θ formula, By correcting the temperature of the heated surface 2h of the heated body 2, the temperature of the temperature calculating surface 2x of the heated body 2 is calculated.

<Fourth embodiment>
Next, a fourth embodiment according to the present invention will be described. The induction heating apparatus according to the fourth embodiment is different from the first to third embodiments in the configuration of the heated body 2 and the function of the heated body temperature calculation unit 64.

As shown in FIG. 13, the heated object 2 according to the fourth embodiment has a housing part that houses the processing object or a passage part through which the processing object passes, and the height is h [m], _{a 1,} a 2 length of n sides, respectively, is a metal cylindrical body forming the (hollow square tubular shape in FIG. 13) hollow n rectangular tube shape ··· _a n [m]. A plurality of jacket chambers 2S in which a gas-liquid two-phase heat medium is enclosed are formed at equal intervals in the circumferential direction along the central axis in the wall thickness of the side peripheral wall of the body 2 to be heated.

  In addition, the winding wire 32 of the present embodiment has a substantially hollow n-square tube shape that is wound around the outer peripheral surface of the heated body 2 having a hollow n-square tube shape. Thereby, the outer peripheral surface of the heated body 2 becomes the heated surface 2h heated by the winding 32.

And the to-be-heated body temperature calculation part 64 calculates the temperature separated from the to-be-heated surface 2h and the temperature of the to-be-heated body 2 in each side wall part calculated | required similarly to the said 1st Embodiment. A temperature difference from the temperature calculation surface 2x, which is a surface to be calculated, is θ _n [° C.], and a distance in the thickness direction between the heated surface 2h and the temperature calculation surface 2x of each side wall portion of the heated object is t. ₁ , t ₂ ,... T _n [m], the temperature difference θ _n obtained from the following equation is used to correct the temperature of the heated surface 2 h of each side wall portion, and each side wall portion The temperature of the temperature calculation surface 2x is calculated.
_{θ n = k n Q n /} (λ n S n / t n)
Here, t _n is the distance [m] between the n-th sidewall heated surface 2h and temperature calculation surfaces in section 2x, S _n is the n th side wall heated surface 2h and temperature calculation surfaces in section 2x the cross-sectional area [m ^2] between, lambda _n is the average temperature thermal conductivity of the heated object at [℃] between the n-th sidewall heated surface 2h and temperature calculation surfaces in section 2x [W / m · ℃] a and, Q _n is the heat value of the heated surface 2h at n-th sidewall part [W], k _n is a correction coefficient calculated from the measured value.

  The heated body temperature calculation unit 64 calculates the temperature of the temperature calculation surface 2x of each side wall portion of the heated body 2 in consideration of the thickness reduction due to the jacket chamber 2S formed in the heated body 2. .

Specifically, the to-be-heated body temperature calculation unit 64 sets S _n [m ² ] as the cross-sectional area between the heated surface 2h and the temperature calculation surface 2x in the nth side wall, and the nth side wall in the nth side wall. The sum of the cross-sectional areas of the jacket chamber between the heated surface 2h and the temperature calculation surface 2x is S _nj [m ² ], and a variable indicating the rate of decrease in the function of the jacket chamber due to the decrease in the pressure of the heat medium accompanying the temperature decrease. When α is α, the distance t _n between the heated surface 2h and the temperature calculation surface 2x in the nth side wall portion is assumed to be a virtual distance t _nj (= αt _n (S _n −S _nj) in consideration of the thickness reduction. ) / S _n ), by using the temperature difference θ obtained from the equation of temperature difference θ, the temperature of the heated surface 2h of each side wall portion of the heated body 2 is corrected, thereby The temperature of the temperature calculation surface 2x of the side wall is calculated.

  The present invention is not limited to the above embodiment.

For example, in the first embodiment, the temperature detection unit 9 that detects the temperature of the winding 32 is embedded in the winding 32, but may be configured as follows.
That is, as shown in FIGS. 14 and 15, the temperature detection operation in which the control device 6 periodically detects the temperature of the winding 32 during the heating operation in which the object to be heated 2 is induced to generate heat to process the object to be heated. You may comprise so that it may perform. More specifically, the control device 6 functions as a DC voltage application unit 66 and a resistance value calculation unit 67.

  The DC voltage application unit 66 controls the DC power supply 12 electrically connected to the winding 32 and applies a DC voltage to the winding 32 intermittently. Specifically, the direct-current voltage application unit 66 applies a constant direct-current voltage to the winding 32 at a constant period of several seconds to several tens of minutes with an application time within several seconds.

  Here, within the application time during which the DC voltage is applied to the winding 32 by the DC voltage application unit 66, the heated body temperature control unit 65 of the control device 6 controls the control element 4 to generate an AC current or an AC voltage. Blocked or minimized. The heated body temperature control unit 65 controls the AC voltage or the AC current by controlling the control element 4 provided in the power supply circuit 5 in order to set the temperature of the heated body 2 to a predetermined set temperature. It is.

  The resistance value calculation unit 67 calculates the winding resistance value of the winding 32 from the DC voltage applied by the DC voltage application unit 66 and the DC current flowing through the winding 32 when a DC voltage is applied to the winding 32. To do. Specifically, the resistance value calculation unit 67 includes a DC voltage of the DC power source 12 input in advance, and a DC current obtained by the DC current detection unit 13 provided in the DC circuit composed of the winding 32 and the DC power source 12. From this, the winding resistance value of the winding 32 is calculated.

  At this time, as described above, at the timing of detecting the DC current by applying the DC voltage, the AC current or AC voltage is cut off or minimized, so that the influence of the AC current (AC component) can be suppressed. Therefore, it is possible to easily detect a direct current (DC component) and to calculate a resistance value with high accuracy.

  Further, in the first, third, and fourth embodiments, the winding 32 is disposed around the outer peripheral surface of the heated body 2 and the heated body 2 is induction-heated from the outer peripheral side. 32 may be disposed in the hollow of the heated body 2 and the heated body 2 may be induction heated from the inner peripheral side. In this case, the inner peripheral surface of the heated body 2 becomes the heated surface. Moreover, in the said 2nd Embodiment, although the temperature calculation surface 2x was the action surface (upper surface) of the to-be-heated body 2, the virtual surface set in the thickness may be sufficient. Further, in the third and fourth embodiments, the temperature calculation surface 2x is a virtual surface set within the thickness of the side wall portion of the heated object 2, but even if it is the inner peripheral surface of the heated object 2. good.

  In addition, it goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. In addition, when there is a difference between the actual measurement value and the calculation value in each calculation process, it goes without saying that correction is performed using a correction coefficient calculated from the actual measurement value.

DESCRIPTION OF SYMBOLS 100 ... Induction heating apparatus 200 ... Induction heating unit 2 ... To-be-heated body 2S ... Jacket chamber 3 ... Magnetic flux generation mechanism 32 ... Winding 4 ... Control element 5 ... Power supply circuit 6 ... Control device 61 ... Impedance calculation unit 62 ... Impedance correction unit 63 ... Temperature calculation data storage unit 64 ... Substrate temperature calculation unit 7 ... Current detection unit 8 ... Voltage detector 9 ... Temperature detector 10 ... Power factor detector

Claims (13)

An induction heating device that is connected to a winding of a magnetic flux generation mechanism and includes a power supply circuit provided with a control element that controls an alternating current or an alternating voltage, and induction-heats an object to be heated by the magnetic flux generation mechanism,
An AC current value obtained from an AC current detection unit that detects an AC current flowing through the winding, an AC voltage value obtained from an AC voltage detection unit that detects an AC voltage applied to the winding, and the object to be heated And a power factor obtained from a power factor detector that detects a power factor of an induction heating unit comprising the magnetic flux generation mechanism, a winding resistance value of the winding, a magnetic flux density generated by the magnetic flux generation mechanism, and the magnetic flux generation mechanism An induction heating apparatus comprising: a heated body temperature calculating unit that calculates the temperature of the heated body using, as a parameter, an excitation resistance value obtained from a relational characteristic with an excitation resistance of a magnetic circuit including the heated body.   The heated body temperature calculation unit includes an AC current value obtained from the AC current detection unit, an AC voltage value obtained from the AC voltage detection unit, a power factor obtained from the power factor detection unit, and the winding. The resistance value of the object to be heated is calculated using the resistance value and the excitation resistance value obtained from the relational characteristics of the magnetic flux density and the excitation resistance of the magnetic circuit as parameters, and the resistance value of the object to be heated and the object to be heated are calculated. The induction heating apparatus according to claim 1, wherein the temperature of the object to be heated is calculated using the relative permeability of the material. A winding temperature detector for detecting the temperature of the winding;
A resistance value calculation unit that calculates the winding resistance value from the temperature of the winding obtained from the winding temperature detection unit;
The induction heating apparatus according to claim 1 or 2, wherein the heated body temperature calculation unit calculates the temperature of the heated body using the winding resistance value obtained from the resistance value calculation unit. A DC voltage application unit that controls a DC power supply and intermittently applies a DC voltage to the winding;
A resistance value calculation unit that calculates the winding resistance value from a DC voltage applied by the DC voltage application unit and a DC current that flows through the winding when the DC voltage is applied;
The induction heating apparatus according to claim 1, wherein the heated body temperature calculation unit calculates the temperature of the heated body using a winding resistance value obtained from the resistance value calculation unit. The heated body has a hollow cylindrical shape,
The magnetic flux generation mechanism is to induction heat the object to be heated from the outer peripheral side or the inner peripheral side,
The heated body temperature calculating unit calculates the temperature of the heated surface of the heated body,
When the temperature difference between the heated surface of the heated object facing the winding and the temperature calculating surface, which is a surface for calculating the temperature, is θ [° C.], the heated object temperature calculating unit includes the heated object temperature calculating unit. The induction heating according to any one of claims 1 to 4, wherein the temperature of the heated surface of the heating body is corrected using a temperature difference θ obtained using the following equation to calculate the temperature of the temperature calculating surface. apparatus.
θ = kP / [2π / {ln (d ₂ / d ₁ ) / λ}]
Here, d ₁ is the diameter [m] of the heated surface, d ₂ is the diameter [m] of the temperature calculating surface, and λ is an average temperature between the heated surface and the temperature calculating surface. The thermal conductivity [W / m · ° C.], P is the heat flow rate [W / m], and k is a correction coefficient calculated from the actual measurement value. A jacket chamber in which a gas-liquid two-phase heat medium is enclosed is formed on the side peripheral wall of the heated body,
The cross-sectional area between the heated surface and the temperature calculation surface is S [m ² ], and the total cross-sectional area of the jacket chamber between the heated surface and the temperature calculation surface is S _j [m ² ], When the distance between the surface to be heated and the temperature calculation surface is t [m], and the variable indicating the rate of function deterioration of the jacket chamber due to the pressure drop of the heat medium accompanying the temperature drop is α,
The heated body temperature calculation unit _sets the diameter d _{1 of the} heated surface as d _j1 = d ₁ ± t {1−α (1−S _j / S)}, and sets the diameter d ₂ of the temperature calculated surface to The induction heating apparatus according to claim 5, wherein the temperature of the object to be heated is corrected using a temperature difference θ obtained as d _j2 = d ₂ ± t {1−α (1−S _j / S)}.
In the formula of d _j1 , the ± part is negative when d ₁ > d ₂ , and is positive when d ₁ <d ₂ . On the other hand, in the formula of d _j2 , the ± part is positive when d ₁ > d ₂ , and is negative when d ₁ <d ₂ . The heated object has a flat plate shape,
The magnetic flux generation mechanism is to induction-heat the object to be heated from one side,
The heated body temperature calculating unit calculates the temperature of the heated surface of the heated body,
When the temperature difference between the heated surface of the heated object facing the winding and the temperature calculating surface, which is a surface for calculating the temperature, is θ [° C.], the heated object temperature calculating unit includes the heated object temperature calculating unit. The induction heating apparatus according to claim 1, wherein the temperature of the heated surface of the heating body is corrected using a temperature difference θ obtained by using the following equation to calculate the temperature of the temperature calculation surface. .
θ = kQ / (λS / t)
Here, t is a distance [m] between the heated surface and the temperature calculating surface, S is a cross-sectional area [m ² ] between the heated surface and the temperature calculating surface, and λ is the above-mentioned It is the thermal conductivity [W / m · ° C.] of the heated body at the average temperature [° C.] between the heated surface and the temperature calculation surface, and Q is the calorific value [W] of the heated surface, k is a correction coefficient calculated from an actual measurement value. The heated body has a hollow n-square tube shape with a height of h [m] and n side lengths of a ₁ , a ₂ ,... A _n [m], respectively.
The magnetic flux generation mechanism is to induction heat the object to be heated from the outer peripheral side or the inner peripheral side,
The heated body temperature calculating unit calculates the temperature of the heated surface of the heated body,
The temperature difference between the heated surface of the heated object facing the winding and the temperature calculating surface that is a surface for calculating the temperature is θ [° C.], and the heated surface on each side of the heated object and the temperature When the distance between the temperature calculation surfaces is t [m], the heated body temperature calculation unit uses the temperature difference θ obtained by using the following equation for the temperature of the heated surface of the heated body. The induction heating apparatus according to any one of claims 1 to 4, wherein the temperature of the temperature calculation surface is calculated by correction.
θ = kQ / λ [{(a ₁ + a ₂ +... + a _n ) h / t} + m _n × n × h]
Here, n is a natural number starting from 1, and λ is the thermal conductivity [W / m · ° C.] of the heated object at an average temperature [° C.] between the heated surface and the temperature calculating surface, Q is the calorific value [W] of the surface to be heated, k is a correction coefficient calculated from actual measurement values, and _mn is a constant at n. A jacket chamber in which a gas-liquid two-phase heat medium is enclosed in the thickness of the heated object is formed,
The cross-sectional area between the heated surface and the temperature calculation surface is S [m ² ], and the total cross-sectional area of the jacket chamber between the heated surface and the temperature calculation surface is S _j [m ² ], When the variable indicating the ratio of the function deterioration of the jacket chamber due to the pressure drop of the heat medium accompanying the temperature drop is α,
The heated body temperature calculation unit uses the temperature difference θ obtained by setting the distance t between the heated surface and the temperature calculating surface as t _j = αt (S−S _j ) / S, and The induction heating apparatus according to claim 7 or 8, wherein the temperature of the heated surface of the body is corrected. The heated body has a hollow n-square tube shape with a height of h [m] and n side lengths of a ₁ , a ₂ ,... A _n [m], respectively.
The magnetic flux generation mechanism is to induction heat the object to be heated from the outer peripheral side or the inner peripheral side,
The heated body temperature calculating unit calculates the temperature of the heated surface of the heated body,
A temperature difference between the heated surface of the heated body facing the winding of each side wall portion of the heated body and a temperature calculation surface which is a surface for calculating the temperature is θ _n [° C.], and the heated When the distance between the heated surface and the temperature calculation surface of each side wall portion of the body is t ₁ , t ₂ ,... T _n [m], the heated body temperature calculation unit The induction according to any one of claims 1 to 4, wherein the temperature of the heated surface of the heated body is corrected using a temperature difference θ _n obtained using the following equation to calculate the temperature of the temperature calculating surface. Heating device.
_{θ n = k n Q n /} (λ n S n / t n)
Here, t _n is the distance between the heated surface and the temperature calculated surface at the n-th sidewall part [m], S _n is the heated surface and the temperature calculated surface at the n-th sidewall part the cross-sectional area [m ^2] between, lambda _n is n th said at side wall portions of the heated surface and thermal conductivity of the object to be heated at an average temperature [℃] between the temperature calculated surface [W / m a · ° C.], Q _n is the heat value of the heated surface of the n-th sidewall part [W], k _n is a correction coefficient calculated from the measured value. A jacket chamber in which a gas-liquid two-phase heat medium is enclosed in the thickness of the heated object is formed,
Let S _n [m ² ] be the cross-sectional area between the heated surface and the temperature calculation surface in the nth side wall portion, and the jacket chamber between the heated surface and the temperature calculation surface in the nth side wall portion. When the sum of the cross-sectional areas is S _nj [m ² ] and the variable indicating the rate of function deterioration of the jacket chamber due to the pressure drop of the heat medium accompanying the temperature drop is α,
The heated object temperature calculation unit obtains the distance t _n between the heated surface and the temperature calculation surface in the nth side wall part as t _nj = αt _n (S _n −S _nj ) / S _n. The induction heating device according to claim 10, wherein the temperature of the heated surface of the heated body is corrected using the temperature difference θ _n . The control element controls a conduction angle of an alternating current or an alternating voltage with a semiconductor,
An impedance calculation unit for calculating the impedance of the object to be heated;
An impedance correction unit that corrects the impedance obtained by the impedance calculation unit based on a conduction angle of the control element;
The induction heating apparatus according to any one of claims 1 to 11, wherein the heated object temperature calculating unit calculates the temperature of the heated object using the corrected impedance corrected by the impedance correcting unit. The heated object temperature calculating unit calculates the temperature of the heated surface, calculates the calculated value of the temperature calculating surface in a steady state from the temperature of the heated surface, and obtains ΔT obtained using the following equation: The induction heating device according to any one of claims 5 to 11 , wherein the temperature of the temperature calculation surface in a transition period is calculated based on the fact that the temperature calculation surface reaches the calculated value after [h] time.
ΔT = k × w × c × t ² / (2λ)
Here, w is the specific gravity [kg / m ³ ] of the material of the heated object, c is the specific heat [kcal / kg · ° C.] of the material of the heated object, and t is the heated surface and the It is the distance [m] between the temperature calculation surfaces, λ is the thermal conductivity [kcal / m · h · ° C.] of the material of the object to be heated, and k is a correction coefficient obtained from the measured value.