JP2015065091A - Induction heating apparatus and induction heating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently control a temperature of a heating object.SOLUTION: An induction heating apparatus 100 comprises: a heating coil 10 heating a heating target part of an object 1; a variable inductor 16 and a variable capacitor 15 provided on a power supply wiring 14a from an AC power supply device 11 to the heating coil 10; and a controller 40 outputting commands to the variable inductor 16 and the variable capacitor 15 so that an inductance and capacitance of the whole system is used as a resonance condition. The controller 40 may comprise: a frequency characteristic calculation part calculating frequency characteristics of the capacitance and inductance of the whole system; a calculation part calculating a capacitance value command and an inductance value command for satisfying the resonance condition to a predetermined excitation frequency; and a reactance command part outputting the capacitance value command and the inductance value command on the basis of the calculation result.

Description

  Embodiments described herein relate generally to an induction heating apparatus and an induction heating method using the same.

  Joining of metal members by brazing is generally widely performed, and examples of the heating source include a torch, a microwave, and an alternating magnetic field. In particular, induction heating using an alternating magnetic field has advantages that it is relatively easy to control temperature and that efficient heating is possible. Induction heating is a widely used heating source, as represented by an IH (Induction Heating) cooker.

  With regard to brazing, techniques aimed at portability, high efficiency, temperature change control, and the like are known. For example, Patent Document 1 discloses a technique for reducing a loss of energy transmission up to a heating coil by incorporating a resonance capacitor in a primary coil of a transformer among a power source, a transformer, and a heating coil that constitute an induction heating device. Yes.

JP 2003-347018 A

  The technique disclosed in Patent Document 1 is effective when a heating object having substantially the same shape and material is continuously applied. This is because the resonance condition in the system including the heating object changes depending on the coupling state of the electromagnetic field determined by the impedance of the heating object and the positional relationship between the heating coil and the heating object.

  Therefore, for example, when mass-produced products are heated on the production line, it is possible to manage fluctuations in resonance conditions due to changes in the impedance of the heating object and the positional relationship between the heating coil and the heating object. . On the other hand, when the existing additional construction is performed or when there are a plurality of component shapes, it is necessary to readjust the inductance and capacitance for determining the resonance condition. Specifically, replacement of a condenser or a transformer occurs according to each heating object.

  In addition, when the part that has already been brazed is in the vicinity of the part to be heated and the temperature of the brazed part should not be increased, it is necessary to efficiently heat and cool the local part. is there. Up to now, there is a technique for cooling the power source in the induction heating apparatus, but the cooling of the part that needs to be cooled is performed by using a cooling mechanism different from the induction heating apparatus. Since there is no device or method for cooling while cooperating with heating, there are problems such as poor bonding of the brazed part due to overcooling and melting of the already brazed part due to insufficient cooling.

  Then, embodiment of this invention aims at controlling the temperature of the target object heated efficiently.

  In order to achieve the above object, an induction heating device according to the present embodiment includes a heating coil for heating a heating target portion of an object, and a variable inductor provided on a power supply wiring from an AC power supply device to the heating coil. And outputs a command to the variable inductor and the variable capacitor so that the inductance and capacitance of the entire system of the variable capacitor provided on the power supply wiring and the object and the induction heating device are resonance conditions. And a control unit.

  In addition, the present embodiment is an induction heating method for heating an object, and includes a low power application step in which an AC voltage is applied to a heating coil with low power, and a state in which a voltage is applied in the low power application step. The frequency is swept within a predetermined range and the frequency, voltage, current, and frequency values are input to the frequency characteristic calculator, and the frequency characteristic of the system is calculated based on the result of the frequency sweep step. A characteristic calculation step; a required reactance calculation step for calculating a required reactance based on the frequency characteristic obtained in the frequency characteristic calculation step; and a reactance adjustment step for adjusting a capacitor and an inductor based on a result of the required reactance calculation step And a predetermined power larger than the low power after the reactance adjustment step. And a frequency adjusting step for adjusting the frequency so as to approach the direction in which the electromagnetic force generated by passing a current through the heating coil in the heating step is maximized. And

  According to the embodiment of the present invention, the temperature of an object to be heated can be efficiently controlled.

It is sectional drawing which shows the structure of the induction heating apparatus which concerns on embodiment. It is a perspective view which shows the division | segmentation coil of the induction heating apparatus which concerns on embodiment. It is a perspective view which shows the modification of the division | segmentation coil of the induction heating apparatus which concerns on embodiment. It is a block diagram which shows the structure centering on the control part of the induction heating apparatus which concerns on embodiment. It is a flowchart which shows the procedure of the induction heating method which concerns on embodiment.

  Hereinafter, an induction heating apparatus and an induction heating method according to an embodiment of the present invention will be described with reference to the drawings. Here, the same or similar parts are denoted by common reference numerals, and redundant description is omitted.

  Drawing 1 is a sectional view showing the composition of the induction heating device concerning an embodiment. The induction heating device 100 heats the heating target surface 2 of the object 1 and cools the cooling target surface 3. The object 1 is, for example, a member such as a conductor that has already been brazed and that is brazed at another position. The induction heating apparatus 100 includes a split coil 10, a power transport unit 14 that sends power to the split coil 10, a cooling mechanism 30, and a control unit 40.

  Two split coils 10 are provided so that they can be heated while sandwiching the object 1. The power transport unit 14 receives AC power for heating the split coil 10 from a separately provided AC power supply device 11 via the transformer 12 and transports the split coil 10 to the split coil 10.

  The power transport unit 14 is provided for each of the two split coils 10, and each power transport unit 14 includes a power supply wiring 14a, a variable capacitor 15 and a variable inductor 16 provided on the power supply wiring 14a, a voltage. A measurement unit 58 and a current measurement unit 59 are included. The variable capacitor 15 is provided with a capacitance adjustment unit 55 (FIG. 4), and the capacitance is variable by a command to the capacitance adjustment unit 55. The variable inductor 16 is provided with an inductance adjusting unit 54 (FIG. 4), and the inductance is variable by a command to the inductance adjusting unit 54.

  In addition, although the case where the variable capacitor 15 and the variable inductor 16 are provided on the secondary side of the transformer 12 is shown, it is not limited to this. It may be provided on the primary side of the transformer 12. Alternatively, it may be provided on both the primary side and the secondary side of the transformer 12. Moreover, although the case where the variable capacitor 15 was provided only in series with the variable inductor 16 was shown, it is not limited to this. For example, the variable capacitor 15 may be further provided in parallel with the variable inductor 16.

  A flexible electric wire 14b is used as the power supply wiring 14a at the connection portion of the power transport unit 14 with the split coil 10 so as not to restrain the movement of the split coil 10. In addition, if it has a softness | flexibility, it will not be limited to an electric wire. For example, a multi-node system having a built-in conductor may be used.

  The cooling mechanism 30 guides the cooling medium from the cooling unit 31 to the cooling unit 32. The cooling unit 32 is formed so that it can be installed in the vicinity of the cooling target surface 3 of the target 1, and the cooling medium cools the air around the cooling unit 32 and indirectly cools the cooling target part. That is, the cooling unit 32 in this case is an indirect cooling unit. Moreover, although not shown in figure, it forms so that a cooling medium is sprayed directly on a cooling object site | part, ie, it can replace | exchange with a direct cooling part. Moreover, it is not limited to exchanging and both may be provided.

  The two divided coils 10 are formed so as to be gripped by the gripping portion 17. A temperature measuring unit 57 and an electromagnetic force measuring unit 56 are attached to the gripping unit 17. The temperature measurement unit 57 may be a radiation thermometer, an infrared thermography, etc. in addition to a thermocouple or a resistance temperature detector. The temperature measuring unit 57 is formed to be exchangeable with each other. The temperature measuring unit 57 measures the temperature of the heating target part of the target object 1 and outputs a temperature signal. Note that when there is a non-heated part with a temperature restriction due to reasons such as being already brazed, the temperature measuring part 57 also has a temperature measuring part of the non-heated part.

  The electromagnetic force measuring unit 56 measures the electromagnetic force due to the magnetic field generated by the current flowing through the split coil 10 and outputs an electromagnetic force signal. As the electromagnetic force measuring unit 56, for example, a strain gauge, a load cell, a magnetic resonance sensor, a magnetoresistive sensor, a torque sensor, or the like can be used.

  FIG. 2 is a perspective view showing a split coil of the induction heating apparatus according to the embodiment. The divided coil 10 is a rectangular divided coil 10a in which a heating part is formed in a rectangular shape. Heating is performed with the rectangular portions facing each other with the object 1 in between. FIG. 3 is a perspective view showing a modification of the split coil of the induction heating apparatus according to the embodiment. In this case, the divided coil 10 is a circular divided coil 10b in which the heating unit is formed in a circular shape.

  The shape of the split coil 10 is not limited to a rectangle or a circle. Moreover, although the case where the two division coils 10 were provided was shown, it is not limited to two. For example, three or more may be used. Alternatively, instead of the plurality of divided coils 10, one coil may be formed to surround the object 1. It is desirable that the divided coil 10 has an appropriate shape and quantity in accordance with the shape of the object 1. Moreover, although the case where the holding | grip part 17 (FIG. 1) was provided in each division | segmentation coil 10 was shown, it is not limited to this. The holding part 17 is good also as what can handle a some division | segmentation coil collectively.

  FIG. 4 is a block diagram illustrating a configuration centering on a control unit of the induction heating apparatus according to the embodiment. The induction heating device 100 further includes a temperature setting unit 51 and a frequency characteristic calculation result storage unit 61. The temperature setting unit 51 receives an input of the set temperature of the heating target part of the target 1 from the outside, and outputs it to the control unit 40. The frequency characteristic calculation result storage unit 61 receives and stores the frequency characteristic calculated by the frequency characteristic calculation unit 42 as an input.

  The control unit 40 includes a calculation unit 41, a frequency characteristic calculation unit 42, a pre-heating excitation command unit 43, a frequency / power command unit 44, and a reactance command unit 45.

  The frequency characteristic calculation unit 42 is a step for grasping the first electrical characteristic, and the frequency target value from the frequency / power command unit 44, the voltage signal from the voltage measurement unit 58, and the current signal from the current measurement unit 59. Accept as input. Based on these signals, the frequency characteristic calculation unit 42 obtains impedance at each frequency, calculates a resistance component, an inductance component, and a capacitance component, and obtains frequency characteristics of these impedance components with respect to the frequency.

  When measurement is performed with the object 1 sandwiched between the split coils 10, this frequency characteristic is the entire characteristic of the object 1 and the induction heating device 100. The frequency characteristic calculation unit 42 outputs the frequency characteristic that is the calculation result to the frequency characteristic calculation result storage unit 61.

  The calculation unit 41 includes a temperature setting signal from the temperature setting unit 51, frequency characteristic information of the entire system from the frequency characteristic calculation result storage unit 61, a temperature signal from the temperature measurement unit 57, and an electromagnetic force signal from the electromagnetic force measurement unit 56. The voltage signal from the voltage measuring unit 58 and the current signal from the current measuring unit 59 are received as inputs. Based on the frequency characteristic information of the entire system, the calculation unit 41 calculates the capacitance value of the variable capacitor 15 and the variable inductor so that the entire system becomes a resonance condition under the specified excitation frequency by the following equation (1). 16 inductance values are calculated.

  In Equation (1), L is an inductance value of the entire system, and C is a capacitance value in the case where it exists in series with the inductance of the entire system.

f = 1 / {2π√ (LC)} (1)
The calculation unit 41 receives and stores external input of data related to the thermal characteristics such as the volume, material, specific heat, and thermal conductivity of the target unit 1, and reflects the temperature signal, Evaluate temperature distribution. Thus, based on the input from the AC power supply device 11 based on the change of the temperature signal from the temperature measurement unit 57, the voltage signal from the voltage measurement unit 58, and the current signal from the current measurement unit 59, the temperature reached by the object 1 is determined. presume. Further, the temperature of the non-heated part is estimated while reflecting the value of the temperature signal of the surface 3 to be cooled, and the flow rate of the cooling medium of the cooling mechanism 30 or the blowing flow rate in the case of direct cooling is calculated.

  The calculation unit 41 outputs a voltage application start command for grasping the frequency characteristics of the entire system, and then a frequency target value range and a frequency sweep command to the pre-heating excitation command unit 43 before heating. In addition, the calculation unit 41 calculates a frequency at which the electromagnetic force signal becomes a predetermined value based on the electromagnetic force signal from the electromagnetic force measurement unit 56, and causes the frequency / power command unit 44 to perform adjustment during heating. Target frequency signal for output. In addition, the calculation unit 41 outputs the target values of the capacitance of the variable capacitor 15 and the inductance of the variable inductor 16 to the reactance command unit 45. Further, the target value of power from the AC power supply device 11 is output to the frequency / power command unit 44. Further, the calculation unit 41 outputs an activation command to the cooling mechanism 30 when the cooling mechanism 30 needs to be activated. Further, the flow rate of the cooling medium or the amount of blowing air is instructed as necessary.

  When receiving the voltage application start command from the calculation unit 41, the pre-heating excitation command unit 43 instructs the AC power supply device 11 to apply a voltage to the power transport unit 14. If there is a switch (not shown) between the AC power supply device 11 and the power transport unit 14, the voltage application start command from the calculation unit 41 may be issued to the switch. Further, upon receiving a frequency sweep command from the calculation unit 41, the preheating excitation command unit 43 outputs a frequency target value to the frequency / power command unit 44, and a command value for the frequency target value within a predetermined frequency range. Change the output step by step.

  The frequency / power command unit 44 outputs a command to the AC power supply device 11 to change the frequency of the supplied power to a new frequency target value based on the command from the preheating excitation command unit 43 and the command from the calculation unit 41. To do. The AC power supply device 11 is a variable frequency power supply, and sweeps the frequency in response to a command. The frequency / power command unit 44 outputs a command to the AC power supply device 11 to change the supplied power to a new target value based on the command from the calculation unit 41.

  The reactance command unit 45 issues a command based on the reactance target from the calculation unit 41 so that the variable capacitor 15 has a target capacitance value and the variable inductor 16 has a target inductance value.

  FIG. 5 is a flowchart showing the procedure of the induction heating method according to the embodiment. First, the induction heating device 100 is set to a heating position (step S01). That is, the object 1 is set in a state in which the object 1 can be heated by sandwiching the object 1 between the divided coils 10.

  After step S01, voltage application to the split coil 10 is started from the AC power supply device 11 with low power (step S02). That is, the calculation unit 41 of the control unit 40 instructs the pre-heating excitation command unit 43 to perform pre-heating excitation. At this time, the electric power supplied from the AC power supply device 11 is set to a low electric power so that the temperature rise of the object 1 can be ignored.

  Next, the frequency of the power supplied from the AC power supply device 11 is swept within a predetermined range while the voltage is applied in step S02 (step S03). That is, the frequency range to be swept is output from the calculation unit 41 of the control unit 40 to the preheating excitation command unit 43. The preheating excitation command unit 43 outputs a frequency range to be swept and a command to be swept to the frequency / power command unit 44. The frequency / power command unit 44 instructs the AC power supply device 11 about the frequency of the power from the AC power supply device 11 and changes the set frequency to be instructed step by step. The AC power supply device 11 matches the frequency of the supplied AC power with the command value from the pre-heating excitation command unit 43.

  Note that the voltage value of the power supplied from the AC power supply device 11 is preferably constant, but may be changed. In response to this change in frequency, the voltage value output from the voltage measurement unit 58, the current value output from the current measurement unit 59, and the frequency command value from the frequency / power command unit 44 are input to the frequency characteristic calculation unit 42, respectively. Is done.

  Based on the voltage value, current value, and frequency input in step S03, the frequency characteristic calculation unit 42 calculates frequency characteristics of the entire system of the induction heating device 100 and the target part 1 to be heated (step S04). The frequency characteristic calculated by the frequency characteristic calculation unit 42 is output to the frequency characteristic calculation result storage unit 61 and stored in the frequency characteristic calculation result storage unit 61.

  After step S04, the calculation unit 41 calculates a necessary reactance value based on the frequency characteristics of the entire system stored in the frequency characteristic calculation result storage unit 61 (step S05). That is, under the specified excitation frequency, the capacitance value of the variable capacitor 15 and the inductance value of the variable inductor 16 are calculated according to the above-described equation (1) so that the entire system is in the resonance condition. The calculation unit 41 outputs the calculated capacitance value of the variable capacitor 15 and the inductance value of the variable inductor 16 to the reactance command unit 45.

  After step S05, the reactance is adjusted based on the output from the calculation unit 41 (step S06). That is, the reactance command unit 45 receiving the output from the calculation unit 41 outputs the inductance value that the variable inductor 16 should take to the inductance adjustment unit 54 and the capacitance value that the variable capacitor 15 should take to the capacitance adjustment unit 55. The inductance adjusting unit 54 adjusts the variable inductor 16 so that the received inductance value is obtained. In addition, the capacitance adjustment unit 55 adjusts the variable capacitor 15 so that the received capacitance value is obtained.

  After the adjustment in step S06 is completed, frequency adjustment is performed based on the electromagnetic force signal from the electromagnetic force measurement unit 56 (step S07). The electromagnetic force signal generated by the current flowing through the split coil 10 is output from the electromagnetic force measuring unit 56. At this time, the calculation unit 41 determines a predetermined width for increasing or decreasing the frequency, and outputs a command to the frequency / power command unit 44 so as to change the frequency within the predetermined width. The frequency / power command unit 44 outputs the frequency command to the AC power supply device 11 within the width of the command received. As a result, the calculation unit 41 determines the frequency at which the electromagnetic force signal from the electromagnetic force measurement unit 56 is the largest as the operation frequency, and instructs the frequency / power command unit 44 to set the determined frequency.

  As a result, as shown in FIG. 4, a magnetic field is generated in the split coil 10 due to the overall electrical characteristics of the induction heating device 100 and the heating object 1. The object 1 is heated by the generation of this magnetic field, and the temperature rises due to its thermal characteristics. These states are fed back to the calculation unit 41 from the electromagnetic force measurement unit 56, the temperature measurement unit 57, and the like.

  After the frequency adjustment in step S07 is completed, the induction heating device 100 starts heating the object 1 from the split coil 10 in response to the supply of predetermined power (step S08). After the start of heating, the temperature signal of the heating target portion measured and output by the temperature measuring portion 57 increases. The computing unit 41 estimates the reached temperature from the tendency of temperature rise. When there is a possibility of exceeding the target temperature, the calculation unit 41 outputs the target power value to the frequency / power command unit 44 so as to lower the power of the AC power supply device 11. As a result, the AC power supply device 11 can reduce the power and bring the attained temperature close to the target temperature.

  In addition, when there is a non-heating part, the temperature of the non-heating part is monitored, and when the specified value is exceeded, the calculation part 41 issues a start command to the cooling mechanism 30. When the cooling mechanism 30 receives the start command, the cooling mechanism 30 cools the non-heating part as a cooling target.

  As described above, according to this embodiment, the temperature of the object to be heated can be efficiently controlled.

  As mentioned above, although embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention.

  For example, in the embodiment, the case where the reactance adjustment and the frequency adjustment are performed only before performing the predetermined heating has been described, but these adjustments may be performed even during the stage where the predetermined heating is performed.

  In the embodiment, the induction heating apparatus 100 does not include the AC power supply apparatus 11 and the transformer 12. 100 may be included. Moreover, these may be integrated and made portable.

  Furthermore, these embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention.

  These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Object, 2 ... Heating object surface, 3 ... Cooling object surface, 10 ... Dividing coil (heating coil), 10a ... Rectangular dividing coil (heating coil), 10b ... Circular dividing coil (heating coil), 11 ... AC power supply Device: 12 ... Transformer, 14 ... Power transport section, 14a ... Power supply wiring, 14b ... Wire, 15 ... Variable capacitor, 16 ... Variable inductor, 17 ... Holding section, 30 ... Cooling mechanism, 31 ... Cooling unit, 32 ... Cooling , 40 ... control part, 41 ... calculation part, 42 ... frequency characteristic calculation part, 43 ... pre-heating excitation command part, 44 ... frequency / power command part, 45 ... reactance command part, 51 ... temperature setting part, 54 ... inductance Adjustment unit, 55 ... capacitance adjustment unit, 56 ... electromagnetic force measurement unit, 57 ... temperature measurement unit, 58 ... voltage measurement unit, 59 ... current measurement unit, 61 ... frequency characteristic calculation result storage unit, 100 ... Electrically heating device

Claims (10)

A heating coil for heating a portion to be heated of the object;
A variable inductor provided on the power supply wiring from the AC power supply device to the heating coil;
A variable capacitor provided on the power supply wiring;
A control unit that outputs a command to the variable inductor and the variable capacitor so that the inductance and capacitance of the entire system of the object and the induction heating device are set as resonance conditions;
An induction heating apparatus comprising: The controller is
A frequency characteristic calculator that calculates frequency characteristics of capacitance and inductance of the entire system;
From the frequency characteristics, a calculation unit that calculates a capacitance value command to the variable capacitor and an inductance value command to the variable inductor to satisfy a resonance condition for a predetermined excitation frequency;
A reactance command unit that outputs the capacitance value command to the variable capacitor and the inductance value command to the variable inductor based on a calculation result in the calculation unit;
The induction heating device according to claim 1, comprising: An electromagnetic force measuring unit for measuring an electromagnetic force generated by passing an electric current through the heating coil;
The induction heating apparatus according to claim 2, wherein the calculation unit calculates a reactance that maximizes an electromagnetic force signal from the electromagnetic force measurement unit, and outputs a calculation result to the reactance command unit.   The induction heating apparatus according to claim 3, wherein the electromagnetic force measurement unit includes at least one of a strain gauge, a load cell, and a torque sensor. The control unit further includes a frequency / power command unit that outputs a frequency command so that the output frequency of the AC power supply device is a predetermined frequency,
The said calculating part calculates the frequency from which the electromagnetic force signal from the said electromagnetic force measurement part becomes a predetermined value, and outputs a calculation result to the said frequency and electric power instruction | command part. The induction heating device according to any one of 4. A non-heating part temperature measuring unit for measuring the surface temperature of the non-heating part having a temperature upper limit in the object;
A cooling mechanism for supplying a cooling medium in the vicinity of the surface of the non-heating unit;
The said calculating part issues a starting command to the said cooling mechanism, if the signal from the said non-heating part temperature measurement part exceeds a predetermined value, The Claim 1 thru | or 5 characterized by the above-mentioned. Induction heating device. The cooling mechanism is
A direct cooling unit that performs cooling by bringing the cooling medium into direct contact with the non-heating unit;
An indirect cooling section that performs cooling by heat transfer with the surface to be cooled;
Have
The direct cooling unit and the indirect cooling unit are formed to be interchangeable with each other,
The induction heating apparatus according to claim 6. A temperature measuring unit for measuring the surface temperature of the object;
The calculation unit estimates a temperature distribution inside the heating target based on a temperature signal from the temperature measurement unit, calculates a flow rate of a cooling medium necessary for cooling the non-heating unit that is a cooling target, and performs the cooling The induction heating apparatus according to claim 6 or 7, wherein a command signal is output to the mechanism.   The induction heating device according to any one of claims 1 to 8, wherein the heating coil is formed so as to surround the object. An induction heating method for heating an object,
A low power application step of applying an alternating voltage to the heating coil with low power;
A frequency sweep step in which the voltage is swept in a predetermined range while a voltage is applied in the low power application step, and the voltage, current, and frequency values during this period are input to the frequency characteristic calculator,
A frequency characteristic calculating step for calculating a frequency characteristic of the system based on the result of the frequency sweep step;
A necessary reactance calculating step for calculating a required reactance based on the frequency characteristic obtained in the frequency characteristic calculating step;
A reactance adjustment step of adjusting a capacitor and an inductor based on the result of the required reactance calculation step;
After the reactance adjustment step, a heating step of performing heating at a predetermined power larger than the low power;
A frequency adjusting step of adjusting the frequency so as to approach a direction in which an electromagnetic force generated by flowing a current through the heating coil in the heating step is maximized;
An induction heating method characterized by comprising:

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