JP2008293990A - Induction heating cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction heating cooker capable of controlling a temperature accurately. <P>SOLUTION: The induction heating cooker is provided with a radiant temperature detecting means 25 detecting a temperature of a bottom surface of a cooking vessel 20 through an infrared-ray transparent material 24 embedded in a top plate 21, and a light-receiving means 27 for detecting light reflected to the bottom surface of the cooking vessel 20 by light of a light-emitting means 26 emitting light toward the bottom surface of the cooking vessel 20 through the top plate 21. The cooker compensates a radiant temperature of the cooking vessel by calculating an emissivity from a reflection factor of the cooking vessel 20 by an output of the light-receiving means 27, and enables to control a temperature accurately. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an induction heating cooker used in general households.

  A conventional induction heating cooker is described, for example, in JP-A-6-302378. This structure will be described with reference to FIG.

A top plate 2 made of a nonmagnetic material is mounted on the upper surface of the main body 1. A cooking container 4 is placed on the top surface of the top plate 2. The cooking container 4 is heated by a heating coil 3 provided below the top plate 2. That is, when a high-frequency current is supplied to the heating coil 3 by the control means 7, the heating coil 3 generates a high-frequency magnetic field, and this high-frequency magnetic field is linked to the cooking container 4 so that the cooking container 4 itself is induction-heated to generate heat. It is. Accordingly, the food stored in the cooking container 4 is heated by the heat generated by the cooking container 4 and cooking proceeds. At this time, the control means 7 adjusts the electric power supplied to the heating coil 3 based on the temperature signal detected by the temperature detection means 6 to control the temperature of the food. At this time, in the technique disclosed in this document, the temperature detection means 6 is attached to the temperature sensing plate 5 to perform accurate temperature control. The temperature sensing plate 5 is made of a non-magnetic material and is attached to the lower surface of the top plate 2.
JP-A-6-302378

  The induction heating cooker having the above-described conventional configuration receives the amount of heat of the cooking container through the top pool and detects the temperature of the temperature sensing plate. It is what you have. That is, since the top plate is made of ceramic and has a low thermal conductivity, the heat transfer to the temperature sensitive plate is delayed as described above.

  The present invention provides a radiation temperature detection means for detecting the radiation temperature of the bottom surface of the cooking container at the lower part of the top plate, controls the power supplied to the heating coil in accordance with the output of the radiation temperature detection means, and provides light to the cooking container. An emissivity calculation means that detects the emissivity by the amount of light that is reflected and incident on the cooking container is provided, and accurate temperature control is performed by detecting the difference in emissivity depending on the material and bottom shape of the cooking container. It is an induction heating cooker that can.

  As described above, according to the present invention, accurate temperature control is possible in the induction heating cooker.

  The invention described in claim 1 is provided with radiation temperature detection means for detecting the radiation temperature of the bottom surface of the cooking container at the lower part of the top plate, and controls the power supplied to the heating coil according to the output of the radiation temperature detection means, In addition, an emissivity calculating means for detecting the emissivity from the amount of light incident on the cooking container after radiating light to the cooking container is provided to detect the difference in emissivity depending on the material and bottom shape of the cooking container. The induction heating cooker is capable of precise temperature control.

The invention described in claim 2 detects the radiation temperature of the bottom surface of the cooking container at the lower part of the top plate, and emits light to the cooking container and detects the emissivity by the amount of light reflected and incident on the cooking container. Accurate temperature control can be performed by providing temperature detection means to detect a difference in emissivity depending on the material and bottom shape of the cooking container.

  According to a third aspect of the present invention, the radiation temperature detecting means is provided with a transmitting material temperature detecting means for detecting the temperature of the infrared transmitting material so as to correct the transmittance of the infrared transmitting material, so that the cooking container is highly accurate. The induction heating cooker is capable of measuring the temperature and controlling the temperature accurately.

  According to a fourth aspect of the present invention, the radiation temperature detecting means is provided with a waveguide for guiding the light incident through the infrared transmitting material to the radiation temperature detecting means, thereby reducing the visual field range for detecting the radiation temperature, By making the shape of the permeable material small, the temperature of the cooking container can be measured with high accuracy, and the induction heating cooker capable of accurate temperature control is obtained.

  In the invention described in claim 5, the radiation temperature detecting means is provided with a heat insulating means for preventing heat from the heating coil and the top plate so that the influence of the surrounding heat is reduced, and an accurate temperature can be measured. It is an induction heating cooker that can control the temperature.

  In the invention described in claim 6, the radiation temperature detection means is provided with a magnetic field shielding means for shielding the induction magnetic field from the heating coil, prevents the influence of the induction magnetic field at the time of heating, and can measure an accurate temperature. The induction heating cooker is capable of precise temperature control.

Example 1
The first embodiment of the present invention will be described below. FIG. 1 is a cross-sectional view showing the configuration of this embodiment. The induction heating cooker of the present embodiment is provided in a cooking container 20 for cooking cooked food, a top plate 21 made of a nonmagnetic material on which the cooking container 20 is placed, and a lower part of the top plate 21. A control means 23 for controlling the power supplied to the heating coil 22, an infrared transmitting material 24 made of a material that transmits infrared light fitted in the top plate 22, and a bottom surface of the cooking vessel 20 through the infrared transmitting material 24. Radiation temperature detecting means 25 for detecting temperature, light emitting means 26 for emitting light toward the bottom surface of the cooking container 20 through the top plate 22, and light reflected by the light from the light emitting means 26 on the bottom surface of the cooking container Light receiving means 27 for detecting the emissivity, and emissivity calculating means 28 for calculating the emissivity from the reflectance of the cooking container 20 based on the output of the light receiving means 27.

  The radiation temperature detecting means 25 is composed of an infrared element that detects infrared rays radiated from the measurement object. The control means 23 adjusts the magnitude of the high-frequency current supplied to the heating coil 22 or controls the power supplied to the heating coil 22 according to the temperature information of the temperature detection means 25.

  The infrared transmitting material 24 is made of a material that transmits infrared light so that the top surface is flattened inside the top plate 21. As the infrared transmitting material, for example, silicon is used, but germanium or the like can also be used. Moreover, it is not limited to a single material. The radiation temperature detecting means 25 may be a sensor capable of detecting infrared rays such as a pyroelectric element or a thermopile.

Hereinafter, the operation of this embodiment will be described. When a power supply (not shown) is turned on and a predetermined temperature is set with the operation switch, the control means 23 supplies power to the heating coil 22. When electric power is supplied to the heating coil 22, an induction magnetic field is emitted from the heating coil 22, and the cooking container 20 on the top plate 21 is induction-heated. Due to this induction heating, the temperature of the cooking container 20 rises and the article to be heated in the cooking container 20 is cooked. At this time, the control means 23 can grasp the progress of cooking of the object to be heated based on the temperature information from the radiation temperature detection means 25, and adjusts the power supplied to the heating coil 22 according to the progress of cooking. is there. Thus, the food to be cooked in the cooking container 20 is cooked.

  The radiation temperature detecting means 25 detects the temperature by detecting the amount of infrared rays radiated from the bottom surface of the cooking vessel 20. The temperature of the cooking vessel 20 is about 30 ° C. to 230 ° C., and the peak wavelength of this temperature is about 10 μm to 6 μm according to Stefan-Boltzmann law. The transmission wavelength of the top plate 21 is about 4 μm or less, and the radiation temperature from the cooking vessel 20 is detected using the infrared transmission material 24. As described above, the infrared transmitting material 24 is configured to be fitted inside the top plate 21 so that the top surface is flat. That is, the top plate 21 has a circular hole so that the temperature sensitive plate 22 is fitted therein. The cooking container 20 is made of a plurality of pans such as aluminum, iron, and stainless steel multi-layer pans. The emissivity varies depending on the material of the cooking container 20 and the shape of the surface, the amount of infrared rays radiated at the same temperature differs, and a temperature detection error occurs.

  At this time, in this embodiment, the light emitting means 26 that emits light to the bottom surface of the cooking container 20 through the top plate 21, the light receiving means 27 that detects the light reflected by the light emitting means 26 on the cooking container 20, The emissivity of the cooking container 20 is corrected by the emissivity calculating means 28 for calculating the emissivity from the reflectance of the cooking container 20 based on the output of the light receiving means 27. The light emitting means 26 emits light to the bottom surface of the cooking container 20 using a near infrared region of about 4 μm or less. This light is reflected by the cooking container 20 and enters the light receiving means 27. The amount of incident light is proportional to the reflectance of the cooking container 20. The light receiving means 27 converts the incident light into an electric signal and sends it to the emissivity calculating means 28. The emissivity calculating means 28 calculates the emissivity from the reflectance signal to obtain the emissivity of the cooking container 20. In this calculation, since the cooking container 20 is made of metal and the transmission of infrared rays is almost 0, the emissivity is obtained by 1-reflectance. Based on this emissivity, the temperature detected by the radiation temperature detecting means 25 is corrected to obtain the temperature of the cooking container 20.

  That is, since the radiation temperature detection means 25 detects the bottom surface of the cooking container 20 in a non-contact manner and calculates the emissivity of the cooking container 20 by the emissivity calculation means 28, the temperature of the cooking container 22 is accurately determined. Can be detected. For this reason, the electric power control with respect to the heating coil 22 of the control means 23 also responds quickly to the temperature change of the cooking vessel 20.

  As described above, according to this embodiment, the cooking container 20 for cooking the cooked food, the top plate 21 made of a non-magnetic material on which the cooking container 20 is placed, and the lower portion of the top plate 21 are provided. The control means 23 for controlling the power supplied to the heating coil 22, the infrared transmitting material 24 fitted in the top plate 21, and the radiation temperature for detecting the temperature of the bottom surface of the cooking vessel 20 through the infrared transmitting material 24 A detecting means 25; a light emitting means 26 for emitting light toward the bottom surface of the cooking container 20 through the top plate 21; and a light receiving means for detecting the light reflected by the light emitting means 26 on the bottom surface of the cooking container 20. 27 and emissivity calculating means 28 for calculating the emissivity from the reflectance of the cooking container 20 based on the output of the light receiving means 27, and detecting the emissivity of the cooking container 20 to detect the cooking capacity. A structure in which to correct the radiation temperature of, realizes the induction heating cooker can accurate temperature control.

(Example 2)
Next, a second embodiment of the present invention will be described. FIG. 2 is a cross-sectional view showing the configuration of this embodiment. In a present Example, it supplies to the heating coil 22 provided in the heat cooking container 20 which cooks a cooking thing, the non-magnetic body which mounts the said cooking container 20, and the lower part of the said top plate 21 Control means 24 for controlling electric power to be transmitted, infrared transmitting material 24 fitted in the top plate 21, light emitting means 26 for emitting light toward the bottom surface of the cooking container 20 through the infrared transmitting material 24, and Radiation temperature detection means 25 for detecting light reflected by the bottom surface of the cooking container 20 through the infrared transmitting material 24 and detecting the temperature of the bottom surface of the cooking container 20; and the radiation temperature detection means 25 And an emissivity calculating means 28 for calculating the emissivity from the reflectance of the cooking container 20 by the output of. The emissivity calculating means 28 detects the emissivity of the cooking container 20 and corrects the radiation temperature of the cooking container 20.

  The second embodiment of the present invention is different from the first embodiment in that light emitting means 26 that emits light toward the bottom surface of the cooking container 20 through the infrared transmitting material 24 and the infrared transmitting material 24 are used. The light source 26 is provided with radiation temperature detecting means 25 for detecting light reflected by the bottom surface of the cooking container 20 and detecting the temperature of the bottom surface of the cooking container 20.

  The light emitting means 24 emits a wavelength in the far infrared region and is radiated to the bottom surface of the cooking vessel 20 through the infrared transmitting material 24. This light is reflected by the bottom surface of the cooking vessel 20 and enters the radiation temperature detecting means 25. The reflectance of the cooking container is detected from this incident light quantity and sent to the emissivity calculating means 28. The emissivity calculating means 28 calculates the emissivity of the cooking container 20 from the reflectance. The radiation temperature detecting means 25 detects the temperature of the bottom surface of the cooking vessel 20. The light emitting means 24 is operated intermittently to perform emissivity detection and radiation temperature detection alternately.

  Because of the above configuration, the emissivity can be detected by the emissivity calculating means 28. Even if the cooking container 20 of a different material is placed, the temperature of the cooking container 20 can be accurately detected. That is, the power control to the heating coil 22 by the control means 23 is more accurate.

  As described above, according to the present embodiment, the light emitting means 26 that emits light toward the bottom surface of the cooking container 20 via the infrared transmitting material 24 and the light of the light emitting means 26 cooks via the infrared transmitting material 24. Radiation temperature detecting means 25 for detecting light reflected on the bottom surface of the container 20 and detecting the temperature of the bottom surface of the cooking container 20, and calculating the emissivity from the reflectance of the cooking container 20 based on the output of the radiation temperature detecting means 25 And an emissivity calculating means 28 for detecting the emissivity of the cooking container made of different materials to detect the radiation temperature, thereby realizing an induction heating cooker capable of accurate temperature control. .

(Example 3)
Next, a third embodiment of the present invention will be described. FIG. 3 is a cross-sectional view showing the configuration of this embodiment. In this embodiment, the radiation temperature detection means is provided with a transmission material temperature detection means 29 for detecting the temperature of the infrared transmission material 24 on the lower surface of the infrared transmission material 24. The transmitting material temperature detecting means 29 is composed of a thermistor and can detect the temperature of the infrared transmitting material 24.

  The infrared transmitting material 24 has a transmittance lower than 100% instead of 100%. In order to increase the transmittance, measures such as an antireflection film are taken, but the transmittance of silicon is about 80%. That is, even if the absorption by the transmissive material is considered as 0, the temperature of the transmissive material is radiated for the remaining 20%. The transmitting material temperature detecting means 29 detects the temperature of the infrared transmitting material 24 and corrects the temperature of the radiation temperature detecting means 25.

  In this embodiment, the temperature of the infrared transmitting material 24 is detected, and the radiation temperature detection error due to the emissivity of the infrared transmitting material 24 is reduced.

As described above, according to the present embodiment, the transmissive material temperature detecting means 29 for detecting the temperature of the infrared transmissive material 24 is provided on the lower surface of the infrared transmissive material 24 so that the radiation temperature detection error due to the emissivity of the infrared transmissive material 24 is reduced. As a reduced configuration, an induction heating cooker capable of detecting a more accurate temperature and performing an accurate temperature control is realized.

Example 4
Next, a fourth embodiment of the present invention will be described. FIG. 4 is a plan view showing the configuration of this embodiment. In this embodiment, the radiation temperature detecting means 25 is provided with a waveguide 30 that guides light incident through the infrared transmitting material 24 to the radiation temperature detecting means 25. The waveguide 30 has a pipe shape made of metal or resin, and the inner surface is finished to a mirror surface by gold plating or the like.

  Hereinafter, the operation of this embodiment will be described. The waveguide 30 can move the light receiving surface of the infrared element in the radiation temperature detecting means 25 to the tip of the waveguide 30. The infrared element has a set viewing angle, and the viewing range becomes large as the distance from the measurement object increases. That is, the visual field range can be reduced so that the temperature of the cooking container 20 can be detected within the range of the infrared transmitting material 24, and unnecessary items can be prevented from entering the visual field range.

  That is, according to the present embodiment, the waveguide 30 that guides the light incident through the infrared transmitting material 24 to the radiation temperature detecting means 25 is provided, and the temperature of the cooking container 20 is reliably detected through the infrared transmitting material 24. Therefore, an induction heating cooker capable of accurate temperature control can be realized.

(Example 5)
Next, a fifth embodiment of the present invention will be described. FIG. 5 is a plan view showing the configuration of this embodiment. In the present embodiment, the radiation temperature detecting means 25 is provided with a heat insulating means 31 for preventing heat from the heating coil 22 and the top plate 21.

  The heat insulating means 31 is made of a non-magnetic vacuum heat insulating material or a highly heat-resistant plastic resin, and is disposed so as to cover the radiation temperature detecting means 25.

  The operation of this embodiment will be described below. The infrared element in the radiation temperature detecting means 25 is sensitive to changes in the operating temperature and is a component that is vulnerable to this thermal fluctuation. The radiation temperature detecting means 25 is disposed at the center of the heating coil 22, and the heating coil 22 is a heat generating component that becomes high temperature during use of the apparatus. Therefore, it is necessary to cool by a cooling fan (not shown) during use of the apparatus. At this time, the cooling fan cools not only the heating coil 22 but also the power element and the like built in the control means 23 at the same time. In the present embodiment, the cooling air from the cooling fan is prevented from affecting the radiation temperature detecting means 25. That is, the heat insulating means 31 prevents temperature fluctuations due to the heat of the heating coil 22 and the cooling air from the cooling fan. That is, the heat insulating means 31 can prevent temperature fluctuation of the radiation temperature detecting means 25, perform temperature detection with higher accuracy, and perform accurate temperature control.

(Example 6)
Next, a sixth embodiment of the present invention will be described. In this embodiment, the radiation temperature detection means 25 is provided with a magnetic field shielding means 32 that shields the induction magnetic field from the heating coil 22. The magnetic field shielding means 32 uses a shielding material such as an aluminum plate.

The operation of this embodiment will be described below. During cooking, an induction magnetic field is generated from the heating coil 22, and the cooking container 20 is heated by this induction magnetic field. The induction magnetic field is provided at the center position of the heating coil 22 and is superimposed on the temperature signal of the radiation temperature detecting means 25. That is, an error occurs in temperature detection of the cooking container 20. The magnetic field shielding means 32 is configured to cover the radiation temperature detecting means 25 so as to shield the induced magnetic field and shields the induced magnetic field. Further, by grounding the magnetic field shielding means 32, the shielding effect can be improved. The magnetic field shielding means 32 can prevent the magnetic field shielding means 32 from being superimposed on the temperature signal of the radiation temperature detecting means 25.

  Therefore, according to the present embodiment, the temperature of the cooking container can be accurately detected even during heating in which an induction magnetic field is generated, and accurate temperature control can be performed.

Sectional drawing which shows the structure of the induction heating cooking appliance which is 1st Example of this invention. Sectional drawing which shows the structure of the induction heating cooking appliance which is a 2nd Example. Sectional drawing which shows the structure of the induction heating cooking appliance which is a 3rd Example. Sectional drawing which shows the structure of the induction heating cooking appliance which is a 4th Example. Sectional drawing which shows the structure of the induction heating cooking appliance which is a 5th Example. Sectional drawing which shows the structure of the induction heating cooking appliance which is a 6th Example. Sectional drawing which shows the structure of the induction heating cooking appliance which is a prior art example

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Cooking container 21 Top plate 22 Heating coil 23 Control means 24 Infrared transmission material 25 Radiation temperature detection means 26 Light emission means 27 Light reception means 28 Emissivity calculation means 29 Transmission material temperature detection means 30 Waveguide 31 Heat insulation means 32 Magnetic field cutoff means

Claims (6)

A cooking container for cooking cooked food, a top plate made of a non-magnetic material on which the cooking container is placed, a control means for controlling power supplied to a heating coil provided at a lower portion of the top plate, Infrared transmitting material fitted into the top plate, radiation temperature detecting means for detecting the temperature of the bottom surface of the cooking container through the infrared transmitting material, and light is emitted toward the bottom surface of the cooking container through the top plate A light emitting means, a light receiving means for detecting the light reflected from the bottom surface of the cooking container, and an emissivity calculating means for calculating the emissivity from the reflectance of the cooking container by the output of the light receiving means, An induction heating cooker that detects the emissivity of the cooking container and corrects the radiation temperature of the cooking container. A heating cooking container for cooking food, a top plate made of a non-magnetic material on which the cooking container is placed, a control means for controlling power supplied to a heating coil provided at a lower portion of the top plate, Infrared transmitting material fitted into the top plate, light emitting means for emitting light toward the bottom surface of the cooking container through the infrared transmitting material, and light of the light emitting means on the bottom surface of the cooking container through the infrared transmitting material Radiation temperature detection means for detecting the reflected light and detecting the temperature of the bottom surface of the cooking container, and emissivity calculation means for calculating the emissivity from the reflectance of the cooking container by the output of the radiation temperature detection means, An induction heating cooker that detects the emissivity of the cooking container and corrects the radiation temperature of the cooking container. The induction heating cooker according to claim 1 or 2, wherein the radiation temperature detection means is provided with a transmission material temperature detection means for detecting the temperature of the infrared transmission material. The induction heating cooker according to any one of claims 1 to 3, wherein the radiation temperature detecting means is provided with a waveguide that guides light incident through the infrared transmitting material to the radiation temperature detecting means. The induction heating cooker according to any one of claims 1 to 4, wherein the radiation temperature detecting means is provided with heat insulating means for preventing heat from the heating coil and the top plate. The induction heating cooker according to any one of claims 1 to 5, wherein the radiation temperature detection means includes magnetic field shielding means for shielding an induction magnetic field from the heating coil.

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