JP5210967B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to an induction heating cooker that detects the temperature of an object to be heated placed on a top plate and controls electric power supplied to a heating coil.

  In a conventional induction heating cooker of this type, there is a type in which the temperature of an object to be heated such as a pan is detected by a thermistor through a top plate and the temperature of the object to be heated is controlled (for example, see Patent Document 1) ).

  Further, an infrared transmitting material is provided on a part of the top plate, an infrared sensor is provided at the lower part of the infrared transmitting material, and infrared rays transmitted through the infrared transmitting material and emitted from the pan are efficiently detected by the infrared sensor. There is one that detects the pan temperature with high accuracy (see, for example, Patent Document 2).

  In addition, a temperature sensor that detects the temperature of the pan and an infrared sensor are provided in the center of the heating coil, and the temperature sensor detects the abnormal heating such as emptying the pan using the temperature sensor. Then, there is one that stops the heating within the guaranteed operating temperature of the infrared sensor and protects the infrared sensor (for example, see Patent Document 3).

Japanese Patent Laid-Open No. 03-269989 Japanese Patent Laid-Open No. 03-208288 JP 2004-273302 A

  In the above-described conventional technology, the one shown in Patent Document 1 detects the temperature of the pan through the top plate, so that an error occurs between the actual pan temperature and the detected temperature of the thermistor due to a time delay. As a result, the temperature of the pan could not be detected with high accuracy.

  Moreover, in order to be able to detect the infrared radiation energy from a pan with an infrared sensor, the thing shown in patent document 2 opens a hole in a top plate, and infrared rays are there there. Since it is configured to embed a material that easily penetrates, the mechanical strength of the top plate is reduced.

  Further, there is a problem that it becomes difficult to clean the surface if there are steps or gaps on the surface of the top plate.

  Moreover, since what is shown in patent document 3 is a structure which an infrared sensor is easy to receive to the influence of the heat_generation | fever of a heating coil, or the temperature rise of a top plate, it had the subject that the temperature of a pan could not be detected accurately.

  In addition, since the ambient temperature of the infrared sensor is likely to increase, heating is frequently stopped to protect the infrared sensor, and thus there is a problem that it is difficult to use as a cooker. .

  In addition, when a Peltier element is used to cool the infrared sensor, the structure becomes complicated and the price is high. In addition, when the infrared sensor is cooled by using a fan, the ambient temperature of the infrared sensor changes due to the fluctuation of the fan's wind, which causes fluctuations in the output signal of the infrared sensor and affects the temperature measurement accuracy. It had the problem that.

  The present invention solves at least one of the problems described above, and provides an induction heating cooker that can accurately detect the temperature of an object to be heated placed on a top plate.

The above-described problems include a heating coil for inductively heating an object to be heated, a coil base in which the heating coil is installed in the upper part, and a plurality of rod-shaped ferrites are radially arranged in the lower part. A top plate on which an object is placed; an infrared sensor that is provided below the coil base and detects infrared rays emitted from the heated object; a shield case having a light receiving hole; and a viewing angle of the infrared sensor. A concave mirror having a paraboloid shape formed by plating a resin housing limited to a narrow field of view of 10 to 15 at the lower surface of the top plate, and an input from the infrared sensor provided in the vicinity of the infrared sensor An operational amplifier for amplifying and outputting, a temperature calculating means for calculating the temperature of the object to be heated from the output of the infrared sensor, and a temperature calculating means An induction heating cooker including control means for controlling power supplied to the heating coil according to an output, wherein the infrared sensor and the operational amplifier are covered with the shield case, and the infrared sensor and the shield Between the cases, a wall made of a resin having a small heat capacity and a low heat transfer rate is provided so as to cover the infrared sensor, and the infrared rays emitted from the heated object are from 10φ to 15φ provided on the top plate. Solved by an induction heating cooker that passes through a temperature detection spot of the size , passes through a light receiving hole provided in the shield case, is bent 90 degrees by the concave mirror, and is received by the light receiving surface of the infrared sensor. it can.

In addition, a heating coil for induction heating the object to be heated, a coil base in which the heating coil is installed in the upper part and a plurality of rod-shaped ferrites are radially arranged in the lower part, and the object to be heated are mounted above the heating coil. A top plate to be placed; an infrared sensor provided below the coil base for detecting infrared rays emitted from the object to be heated; and an input from the infrared sensor provided in the vicinity of the infrared sensor for amplification and output An operational amplifier, a substrate on which the infrared sensor and the operational amplifier are mounted, a shield case that covers the infrared sensor, the operational amplifier and the substrate, and a viewing angle of the infrared sensor provided in the shield case. The resin housing, which is limited to a narrow field of view of 10φ to 15φ at the position of A concave mirror having a surface shape, temperature calculating means for calculating the temperature of the object to be heated from the output of the infrared sensor, and control means for controlling the power supplied to the heating coil in accordance with the output of the temperature calculating means. An induction heating cooker provided, wherein a wall made of a resin having a small heat capacity and a poor heat transfer rate is provided between the infrared sensor and the shield case so as to cover the infrared sensor, and the object to be heated The infrared rays radiated through the temperature detection spot having a size of 10φ to 15φ provided on the top plate , passed through a light receiving hole provided in the shield case, and bent by 90 degrees with the concave mirror, It can also be solved by an induction heating cooker that receives light on the light receiving surface of the infrared sensor.

  The induction heating cooker according to the present invention is configured as described above, so that the influence of infrared radiation from the top plate itself can be reduced, the ambient temperature of the infrared sensor can be stabilized, and the temperature of the pan can be accurately adjusted. An induction heating cooker that can be detected can be realized.

It is an external appearance perspective view of the induction heating cooking appliance in the 1st Example of this invention. It is a principal part longitudinal cross-sectional view of an induction heating cooking appliance similarly. It is a principal part longitudinal cross-sectional view of an induction heating cooking appliance similarly. It is a graph which shows the spectral radiant intensity curve of a black body. It is a graph which shows the transmittance | permeability curve of crystallized glass. It is a principal part longitudinal cross-sectional view of the induction heating cooking appliance in the 2nd Example of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an external perspective view of the induction heating cooker in the first embodiment, FIGS. 2 and 3 are longitudinal sectional views of main parts of the induction heating cooker in the first embodiment, and FIG. 4 is a spectral radiant intensity of a black body. FIG. 5 is a graph showing a transmittance curve of crystallized glass.

  In FIG. 1, the top plate 2 is horizontally arrange | positioned on the upper surface of the main body 1 of the induction heating cooking appliance.

  The top plate 2 is made of crystallized glass having high heat resistance, and places an object to be heated such as a pot 30 made of a magnetic material such as iron or a non-magnetic material such as aluminum.

  Heating coils 3 are arranged on the upper left and right sides of the main body 1 below the top plate 2 to inductively heat an object to be heated such as a pan 30 placed on the top plate 2.

  An operation unit 7 corresponding to each heating coil 3 is provided on the upper surface on the front side of the top plate 2, and the energization state of the heating coil 3 is set and operated. Further, a display unit 8 is provided in the vicinity of the operation unit 7 corresponding to the operation unit 7 and displays the energization state of each heating coil 3.

  An intake port 4 opened upward is provided on the right side of the rear portion of the main body 1, and cooling air 20 (FIG. 2) sucked from the intake port 4 by a fan 11 (FIG. 2) provided in the main body 1. Is passed through a control board (not shown) provided in the main body 1, the heating coil 3, and the like to be cooled.

  An exhaust port 5 for exhausting the cooling air 20 that has cooled the inside of the main body 1 is provided on the rear left side of the main body 1.

  A grill heating unit 6 is provided on the left side of the front surface of the main body 1.

  2 and 3, the heating coil 3 has a donut-like disk shape and is installed on a coil base 9 provided in the main body 1 below the top plate 2.

  A plurality of rod-like ferrites 10 are radially arranged below the coil base 9, and the magnetic flux generated from the heating coil 3 spreads below the coil base 9, causing errors in nearby metals and electronic components. It is intended to prevent heating, and makes it difficult for electronic components to be affected by noise caused by magnetic lines of force.

  The coil base 9 on which the heating coil 3 is installed is urged in the direction of the top plate 2 by a plurality of springs (not shown), and the heating coil 3 is configured to be substantially parallel to the top plate 2. .

  A temperature sensor 17 made of a thermistor is provided in close contact with the lower surface of the top plate 2 at a substantially central portion of the heating coil 3, and detects the temperature of the pan 30 via the top plate 2. When the pan 30 or the like is abnormally heated, the temperature sensor 17 detects the abnormal temperature, and the safety is ensured by stopping energization of the heating coil 3 so that the safety is not impaired.

  Below the center of the heating coil 3 is provided an infrared sensor 12 that detects infrared radiation emitted from the bottom surface of the pan 30, and the light receiving surface 12 a of the infrared sensor 12 is the center of the inner diameter A of the heating coil 3. From the lower surface of the top plate 2 at a position within 1/4 of the inner diameter A.

  The infrared sensor 12 is a sensor using a thermal detection element, and a concave mirror 14 having a paraboloid shape formed by plating a resin housing is provided on the front surface of the light receiving surface 12a. The infrared rays radiated from the pan 30 pass through the top plate 2 and enter the concave mirror 14, and are then bent 90 degrees to the right and received by the light receiving surface 12a.

  Therefore, the viewing angle of the infrared sensor 12 is limited by the concave mirror 14, and the viewing angle is such that a temperature detection spot 25 of 10 to 15φ is detected at the position of the lower surface of the top plate 2 as shown in FIG. .

  In the present embodiment, the parabolic concave mirror 14 is provided on the front surface of the light receiving surface 12a of the infrared sensor 12 in order to narrow the viewing angle of the infrared sensor 12, but a convex lens shape is provided on the light receiving surface 12a. You may put it on the front.

  The infrared sensor 12 is soldered and mounted on the substrate 15, and an output signal from the light receiving surface 12 a of the infrared sensor 12 is input to an operational amplifier (not shown) mounted on the substrate 15, converted into a voltage, and output. .

  As is apparent from the spectral radiant intensity curve of the black body shown in FIG. 4, the infrared energy radiated from an object generally radiates as a greater amount of infrared energy as the temperature increases to 100 ° C., 200 ° C., 300 ° C., and 400 ° C. To do. Further, the peak of the curve is closer to the short wavelength side when the temperature is high, and to the long wavelength side when the temperature is low.

  When the pan 30 is heated and the temperature rises, the higher the temperature is, the higher the energy is emitted as infrared rays, as shown in FIG. 4. Approaches the long wavelength side.

  And the infrared rays radiated from the pan 30 pass through the crystallized glass top plate 2 and enter the infrared sensor 12. However, since the crystallized glass has infrared transmittance curve characteristics as shown in FIG. 5, it transmits only infrared rays having a wavelength of 4 μm or less among infrared rays emitted from the pan 30.

  Therefore, the infrared energy incident on the infrared sensor 12 is weak, but is amplified from 5000 to 10,000 times by an operational amplifier provided in the vicinity of the infrared sensor 12 and then output from the pan 30 incident on the infrared sensor 12. The converted infrared energy is converted into an electrical signal, and a voltage corresponding to the amount of energy is output.

  The infrared sensor 12 and the substrate 15 are made of a magnetic shielding member made of a steel plate so as not to be affected by the magnetic field generated when the pan 30 is induction-heated by the heating coil 3 and to suppress fluctuations in the ambient temperature. Covered with a shield case 16.

  The shield case 16 has a light receiving hole 18 for making the infrared ray radiated from the pan 30 incident on the upper surface, and the infrared ray radiated from the pan 30 is incident on the light receiving surface 12 a of the infrared sensor 12 in the light receiving hole 18. A heat shield plate 19 having an infrared transmission characteristic is attached to prevent the infrared rays emitted from the top plate 2 itself from entering the light receiving surface 12 a of the infrared sensor 12.

  The heat shield 19 is closely attached to the inner peripheral edge (or the outer peripheral edge) of the light receiving hole 18 of the shield case 16 without a gap, and is configured so that there is no air flow inside and outside the shield case 16. ing.

  The infrared transmission characteristics of the heat shield plate 19 are such that infrared rays having a wavelength region of 4 μm or less are transmitted and infrared rays having a wavelength region of 4 μm or more are attenuated. By having such properties, the top plate 2 High-accuracy temperature detection is possible by blocking the radiant heat generated by itself and the coil base 9 holding the heating coil 3 from infrared rays having a wavelength range of 4 μm or more so as not to enter the light receiving surface 12a of the infrared sensor 12. It is said.

  Further, the heat shield plate 19 may be made of crystallized glass, which is the same material as the top plate 2. In this case, when the infrared rays transmitted through the top plate 2 pass through the heat shield plate 19, FIG. As shown in FIG. 4, infrared rays having a wavelength region of 4 μm or more can be attenuated so as not to be transmitted, and infrared energy radiated from the pan 30 can be efficiently incident on the infrared sensor 12.

  The infrared sensor 12 is covered with the shield case 16 as described above, and is installed in a place that is not easily affected by the magnetic flux generated from the heating coil 3 below the coil base 9 on which the heating coil 3 is placed.

  However, if the shield case 16 is heated even under the coil base 9 and the temperature rises, the temperature detection of the infrared sensor 12 is affected. Therefore, by cooling the shield case 16 with the cooling air 20 by the fan 11 disposed at an appropriate position in the main body 1, temperature measurement with higher accuracy is possible.

Thus, the infrared sensor 12 is not affected by the leakage magnetic flux of the heating coil 3, and is provided at a position that is not easily affected by the temperature rise due to the heat generation of the heating coil 3 or the temperature rise of the top plate 2 itself. For this purpose, the light receiving surface 12 of the infrared sensor 12 is experimentally determined.
at the position of 1/4 within the said inner diameter A from the center of the inner diameter A of the heating coil 3 to a, by arranging a position away 40mm from 32mm from the lower surface of the top plate 2, and allows for more accurate temperature measurements We were able to.

  One end of the temperature calculation means 21 is connected to the substrate 15 on which the infrared sensor 12 is mounted, and a signal obtained by converting the infrared energy of the pot 30 detected by the infrared sensor 12 into an electrical signal is input to the temperature calculation means 21. .

  The temperature calculation means 21 calculates the temperature of the pan 30 from the input electric signal, and outputs the result to the control means 22 connected to the other end of the temperature calculation means 21.

  The control means 22 is connected to one end of an inverter power supply 23 that supplies power to the heating coil 3, and the heating coil 3 is connected to the other end of the inverter power supply 23.

  This embodiment is configured as described above. The operation is performed by turning on a power switch (not shown) and operating the operation unit 7 while setting the predetermined temperature while viewing the display on the display unit 8. The inverter power supply 23 is controlled to supply predetermined power to the heating coil 3.

  When electric power is supplied to the heating coil 3, a high-frequency magnetic field is emitted from the heating coil 3 and the pot 30 placed on the top plate 2 is induction-heated.

  Due to this induction heating, the temperature of the pan 30 rises, and the infrared rays radiated from the pan 30 by this temperature rise pass through the top plate 2 and through the heat shield plate 19 from the light receiving hole 18 on the upper surface of the shield case 16, thereby forming a concave mirror 14, the light is bent 90 degrees right and received by the light receiving surface 12 a of the infrared sensor 12.

  At this time, the viewing angle of the infrared sensor 12 is limited by the concave mirror 14, and the temperature detection spot 25 of 10 to 15 φ is detected at the position of the lower surface of the top plate 2.

  The infrared light detected by the infrared sensor 12 is converted into an electrical signal, and the converted electrical signal is input to the temperature calculation means 21 that calculates the temperature of the pot 30.

  The temperature information of the pot 30 calculated by the temperature calculating means 21 is input to the control means 22 that controls the power supplied to the heating coil 3 according to the temperature of the pot 30, and the control means 22 controls the inverter power supply 23 to heat it. The electric power supplied to the coil 3 is controlled.

  According to the above-described embodiment, the heat shield plate 19 that covers the light receiving surface 12a of the infrared sensor 12 transmits infrared light having a wavelength range of 4 μm or less, and has an attenuation characteristic of infrared light having a wavelength range of 4 μm or more. With this characteristic, the light receiving surface of the infrared sensor 12 is shielded by blocking the radiant heat generated by infrared rays in the wavelength region of 4 μm or more emitted from the top plate 2 itself, the coil base 9 holding the heating coil 3 or the like. In order not to enter into 12a, temperature detection with high accuracy can be performed.

  Further, when the heat shield plate 19 is made of crystallized glass made of the same material as that of the top plate 2, when the infrared rays transmitted through the top plate 2 pass through the heat shield plate 19, the infrared transmission characteristics are the same as those of the top plate 2. Since it is the same, infrared rays in a wavelength region of 4 μm or more can be attenuated so as not to be transmitted, and infrared energy radiated from the pan 30 can be efficiently incident on the infrared sensor 12.

  Moreover, it can be set as an inexpensive structure by using the same thing as the cheap top plate 2 for the heat shield plate 19 without using an expensive optical filter.

  Further, since the infrared sensor 12 is disposed in a space sealed by the shield case 16 made of a steel plate, the infrared sensor 12 is not affected by the magnetic flux from the heating coil 3 and the ambient temperature of the infrared sensor 12 is stable. Therefore, accurate temperature detection by the infrared sensor 12 becomes possible, and stable heating control can be performed.

  The heat shield plate 19 is attached to the peripheral portion of the light receiving hole 18 of the shield case 16, and most of the heat shield plate 19 is covered with the shield case 16, so that the top plate 2 itself and the heating coil 3 are connected to each other. Since the area exposed to the infrared rays emitted from the holding coil base 9 and the like is small, the temperature rise of the heat shield plate 19 is suppressed, and the infrared energy emitted by the temperature rise of the heat shield plate 19 is incident on the infrared sensor 12. And it can suppress that the temperature detection precision of the pan 30 deteriorates.

  Further, since the light receiving hole 18 of the shield case 16 is sealed with the heat shield plate 19, when the cooling air 20 is applied to the shield case 16 for cooling, the cooling air 20 enters the shield case 16 and surrounds the infrared sensor 12. The temperature is not changed. Therefore, the influence of the fluctuation in the output signal of the infrared sensor 12 can be eliminated, and the temperature can be detected with high accuracy.

  Further, by cooling the shield case 16 with the cooling air 20 from the fan 11, temperature measurement with higher accuracy can be performed.

  Further, the light receiving surface 12a of the infrared sensor 12 is disposed at a position within 14 of the inner diameter A from the center of the inner diameter A of the heating coil 3, and at a position away from 32 mm to 40 mm from the lower surface of the top plate 2. As a result, the temperature near the center of the pan 30 can be detected, and the temperature can be made less susceptible to the influence of radiant heat from the heating coil 3, the coil base 9, and the like, and highly accurate temperature detection is possible.

  FIG. 6 shows a longitudinal sectional view of the main part in the second embodiment of the present invention.

  In FIG. 6, the same parts as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  In this embodiment, the wall 24 is provided between the shield case 16 and the infrared sensor 12 with a resin having a small heat capacity and a low heat transfer coefficient.

  As described above, by arranging the infrared sensor 12 in the space covered by the wall 24, the shield case 16 is affected by the influence of leakage magnetic flux from the heating coil 3 and the temperature rise of the top plate 2 and the heating coil 3. Even if the temperature changes, the influence of the temperature is not easily transmitted to the infrared sensor 12, so that it is possible to detect the temperature with high accuracy.

  Further, since the infrared sensor 12 is covered by the wall 24, even if there is a slight gap in the shield case 16 and the cooling air 20 enters the shield case 16, the ambient temperature of the infrared sensor 12 does not fluctuate.

2 Top plate 3 Heating coil 12 Infrared sensor 12a Light receiving surface 16 Shield case 18 Light receiving hole 19 Heat shield plate 20 Cooling air 21 Temperature calculating means 22 Control means 24 Wall 25 Temperature detection spot

Claims (3)

A heating coil for inductively heating an object to be heated;
A coil base in which a plurality of rod-like ferrites are radially arranged in the lower part while the heating coil is installed in the upper part,
A top plate for placing an object to be heated above the heating coil;
An infrared sensor that is provided below the coil base and detects infrared rays emitted from the object to be heated;
A shield case having a light receiving hole;
A concave mirror having a parabolic shape formed by plating a resin housing that restricts the viewing angle of the infrared sensor to a narrow field of view of 10 to 15 at the position of the lower surface of the top plate ;
An operational amplifier provided in the vicinity of the infrared sensor for amplifying and outputting the input from the infrared sensor;
Temperature calculating means for calculating the temperature of the object to be heated from the output of the infrared sensor;
An induction heating cooker comprising control means for controlling the power supplied to the heating coil in accordance with the output of the temperature calculating means,
The infrared sensor and the operational amplifier are covered with the shield case,
Between the infrared sensor and the shield case, a wall made of a resin having a small heat capacity and a poor heat transfer rate is provided so as to cover the infrared sensor,
Infrared rays emitted from the object to be heated are
It passes through a temperature detection spot having a size of 10 to 15 φ provided on the top plate,
Pass through the light receiving hole provided in the shield case,
After being bent by 90 degrees with the concave mirror, the induction heating cooker is received by the light receiving surface of the infrared sensor. A heating coil for inductively heating an object to be heated;
A coil base in which a plurality of rod-like ferrites are radially arranged in the lower part while the heating coil is installed in the upper part,
A top plate for placing an object to be heated above the heating coil;
An infrared sensor that is provided below the coil base and detects infrared rays emitted from the object to be heated;
An operational amplifier provided in the vicinity of the infrared sensor for amplifying and outputting the input from the infrared sensor;
A substrate on which the infrared sensor and the operational amplifier are mounted;
A shield case covering the infrared sensor, the operational amplifier and the substrate;
A concave mirror having a parabolic shape formed by plating a resin housing provided in the shield case and restricting the viewing angle of the infrared sensor to a narrow field of view of 10 to 15 at the position of the lower surface of the top plate ; ,
Temperature calculating means for calculating the temperature of the object to be heated from the output of the infrared sensor;
An induction heating cooker comprising control means for controlling the power supplied to the heating coil in accordance with the output of the temperature calculating means,
Between the infrared sensor and the shield case, a wall made of a resin having a small heat capacity and a poor heat transfer rate is provided so as to cover the infrared sensor,
Infrared rays emitted from the object to be heated are transmitted through a temperature detection spot having a size of 10 to 15φ provided on the top plate,
Pass through the light receiving hole provided in the shield case,
After being bent by 90 degrees with the concave mirror, the induction heating cooker is received by the light receiving surface of the infrared sensor. In the induction heating cooker according to claim 1 or 2,
The said infrared sensor is provided under the center part of the said heating coil, The induction heating cooking appliance characterized by the above-mentioned .

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