JP2005149829A - Induction heating cooker - Google Patents

Abstract

In an induction heating cooker, the temperature of a pan placed on a top plate is accurately detected.
SOLUTION: A heating coil 3 for heating a pan 1, a top plate 2 for placing the pan on the top of the heating coil 3, and an infrared detection for detecting infrared rays placed on the bottom surface of the top plate 2 and emitted from the bottom surface of the pan 1. Means 5, first and second magnetic shield means 6 and 7 for shielding the infrared detecting means 5 from the magnetic field of the heating coil 3, and temperature detecting means 10 for detecting the bottom temperature of the pan 1 from the output of the infrared detecting means 5. And a control means 11 for controlling the power supplied to the heating coil 3 according to the output of the temperature detection means 10, and the first and second magnetic shield means 6, 7 and the zero potential of the infrared detection means 5 are connected. Thus, the induction heating cooker is capable of accurately detecting and controlling the amount of infrared rays from the pan 1 without being affected by the magnetic field.
[Selection] Figure 1

Description

  The present invention relates to an induction heating cooker that can accurately detect the temperature of a cooking container such as a pan on a top plate.

  In an induction heating cooker that heats an object to be heated such as a pan, as a method of detecting the temperature of the pan, there is a method of detecting the temperature with a thermistor through a top plate on which the pan is placed. In addition, there is an apparatus for detecting the temperature by detecting the infrared ray radiated from the side surface of the pan with an infrared sensor located behind the top surface of the top plate. Furthermore, an infrared sensor is arranged on the lower surface of the top plate to detect infrared rays from the pan through the top plate (for example, see Patent Document 1).

  In a conventional induction heating cooker, when the thermistor receives the temperature of the pan through the top plate and detects the temperature, the ceramic top plate has a low heat transfer coefficient. Due to the delay in response, the actual pan temperature and error occur, and the pan temperature cannot be detected accurately.

Further, in the induction heating cooker having the conventional configuration shown in FIG. 6, the infrared sensor 15 behind the top plate 2 is affected by disturbance light such as sunlight or illumination, and cannot accurately detect the temperature. Furthermore, in an induction heating cooker with a configuration in which an infrared sensor is arranged on the bottom of the top plate, the infrared sensor is affected by the magnetic field from the heating coil, and the output voltage drifts when the power is turned on and off, allowing stable temperature measurement. I can't.
Japanese Patent Laid-Open No. 03-184295

  In view of the problems of the prior art, the problem to be solved by the present invention is to provide an induction heating cooker that can accurately detect the temperature of a cooking vessel without being affected by the magnetic field of induction heating.

  The present invention provides a heating coil for heating a cooking container, a top plate on which the cooking container is placed above the heating coil, and infrared rays that are placed under the top plate and emitted from the bottom surface of the cooking container. Infrared detecting means for detecting, magnetic shielding means for protecting the infrared detecting means from the magnetic field by shielding the magnetic field from the heating coil, temperature detecting means for detecting the temperature of the cooking container from the output of the infrared detecting means, By connecting the control means for controlling the power supplied to the heating coil in accordance with the output of the temperature detection means, and the zero potential of the magnetic shield means and the infrared detection means, it is possible to remove from the cooking container without being affected by the magnetic field. This is an induction heating cooker that can accurately detect the amount of infrared rays and control the power.

  The induction cooking device of the present invention can accurately detect the temperature of the cooking container without being affected by the magnetic field of induction heating.

  The first invention is a heating coil for heating a cooking container, a top plate for placing the cooking container above the heating coil, and an infrared ray placed under the top plate and emitted from the bottom surface of the cooking container. Infrared detection means for detecting the magnetic field from the heating coil to shield the infrared detection means from the magnetic field, temperature detection means for detecting the temperature of the cooking container from the output of the infrared detection means, Control means for controlling the power supplied to the heating coil in accordance with the output of the temperature detection means, wherein the magnetic shield means and the zero potential of the infrared detection means are connected, and the temperature of the cooking container is stably controlled. It is an induction heating cooker that can be detected accurately.

  2nd invention is located inside the magnetic-shielding means in 1st invention, and provided the reflection means in the path | route from the upper part of a magnetic-shielding means to an infrared rays detection means, The infrared rays from a cooking container are effective. It is an induction heating cooker that can guide and stably detect the temperature of the cooking container.

  According to a third invention, in the second invention, a protective layer that easily transmits infrared rays is formed on the inner surface of the reflecting means, so that deterioration of the reflecting means can be suppressed, and the temperature of the cooking container can be more accurately and accurately determined. This is an induction heating cooker that can be detected by

  The fourth invention is the one in which the diameter of the upper part of the reflecting means in the second invention or the third invention is increased, and is not easily affected by ambient light or infrared rays from the heating coil, and the temperature of the cooking container is accurately set. This is an induction heating cooker that can be detected.

  According to a fifth aspect of the present invention, an opening for receiving cooling air for cooling the infrared detecting means is provided in a part of the magnetic shielding means in any one of the first to fourth aspects of the invention. This is an induction heating cooker that can stably detect the temperature of the cooking container more stably.

  According to a sixth aspect of the present invention, a lens is provided on the window member of the infrared detecting means according to any one of the first to fifth aspects of the invention. The amount of infrared rays incident on the infrared detecting means can be greatly increased, and S / N The induction heating cooker can improve the ratio and detect the temperature of the cooking container more accurately.

  7th invention puts on the heating coil which heats a cooking vessel, the top plate which mounts the said cooking vessel above the said heating coil, and the said top plate, and radiates | emits from the bottom face of the said cooking vessel. Infrared detection means for detecting infrared rays, magnetic shield means for shielding the infrared detection means from the magnetic field by shielding the magnetic field from the heating coil, and temperature detection means for detecting the temperature of the cooking container from the output of the infrared detection means, A control means for controlling the power supplied to the heating coil in accordance with the output of the temperature detecting means; and when the amount of change in the infrared detecting means exceeds a predetermined value, the power supplied to the heating coil is reduced. Therefore, an induction heating cooker that can prevent the temperature of the cooking container from rising abnormally is provided.

  The eighth invention is a heating coil for heating a cooking vessel, a top plate for placing the cooking vessel above the heating coil, and placed under the top plate and radiated from the bottom surface of the cooking vessel. Infrared detection means for detecting infrared rays, magnetic shielding means for shielding the infrared detection means from the magnetic field by shielding the magnetic field from the heating coil, amplification means for amplifying the output of the infrared detection means, and output of the amplification means Temperature detecting means for detecting the temperature of the cooking container, control means for controlling the power supplied to the heating coil according to the output of the temperature detecting means, and switching means for varying the amplification factor of the amplifying means. This is an induction heating cooker that can more accurately detect the temperature range of the cooking container according to the menu.

  The object of the present invention can be achieved by using the first to eighth aspects of the present invention as the main part of the embodiment, so the details of the embodiment corresponding to each claim will be described below with reference to the drawings. It will be described and the best mode for carrying out the present invention will be described. The present invention is not limited to the following embodiments. Further, in the description of each embodiment, the same configurations and functions and effects are denoted by the same reference numerals, and redundant description will not be given.

(Embodiment 1)
FIG. 1 is a block diagram showing the configuration of the induction heating cooker according to Embodiment 1 of the present invention. The induction heating cooker supplies a high frequency current to the pan 1, which is a cooking container for cooking the object to be heated, the top plate 2 on which the pan 1 is placed, the heating coil 3, and the heating coil 3. The first high-frequency inverter 4 and the second magnetic-shielding means 7 are the magnetic-shielding means that shields the magnetic field from the heating coil 3 and protects the infrared-detecting means 5 from the magnetic field. And a cylindrical reflecting means 8 for guiding infrared rays from the pan 1 to the infrared detecting means 5 and a first magnetic preventing means 6 for reducing the influence of temperature rise inside the apparatus. The heat insulating means 9 covering the lower opening, the temperature detecting means 10 for detecting the bottom temperature of the pan 1 from the output of the infrared detecting means 5, and the electric power supplied to the heating coil 3 are controlled according to the output of the temperature detecting means 10. And control means 11 .

  And the 1st magnetic-shielding means 6 makes | forms the cylinder shape which opened up and down, the upper side fits in the center part of the heating coil 3, and the lower side is arrange | positioned under the heating coil 3. FIG. The 2nd magnetic-shielding means 7 is located in the lower part side of the 1st magnetic-shielding means 6, and is arrange | positioned so that it may cover. Accordingly, the outer periphery is shielded by the first and second magnetic shielding means except that the infrared detection means 5 detects the infrared light incident from the opened upper side of the first magnetic shielding means 6. The first magnetic shield means 6 and the second magnetic shield means 7 are grounded, and the infrared detection means 5 is provided on the substrate 16. The substrate 16 is fixed to the first magnetic shield means 6 with a screw 17, and the first The first and second magnetic shield means 6 and 7 are connected to the zero potential of the infrared detecting means 5.

  In the above embodiment, when a power supply (not shown) is turned on and a predetermined temperature is set with the operation switch, electric power is supplied from the high-frequency inverter 4 to the heating coil 3 under the control of the control means 11. When electric power is supplied to the heating coil 3, an induction magnetic field is generated in the heating coil 3, and the pan 1 on the top plate 2 is induction-heated. Due to this induction heating, the temperature of the pan 1 rises and the object to be heated in the pan 1 is cooked.

  Here, the operation of the infrared detecting means 5 will be described. When the temperature of the pan 1 rises, infrared rays corresponding to the temperature are emitted from the pan 1. Since the glass ceramic used for the top plate 2 can efficiently transmit infrared rays having a wavelength range of 2.5 μm or less, the infrared detecting means 5 is constituted by, for example, a photodiode that can detect wavelengths of 2.5 μm or less. Infrared light of this wavelength range that has passed through the top plate 2 is incident on the photodiode.

  Further, the cylindrical reflecting means 7 having the same diameter has a high mirror surface configuration with an inner surface reflectance of about 0.9 so that more infrared rays can be collected and incident on the photodiode. . Also, the high reflectance means that the emissivity is low, so there is almost no infrared radiation from the reflecting means itself. Further, the reflecting means 8 prevents the temperature of the heating coil 3 and the holding portion of the heating coil 3 from being affected by the temperature from the lateral direction of the infrared detecting means 5.

  Therefore, only the infrared rays from the pan 1 are incident on the infrared detection means 5, and the diode current corresponding to the amount of infrared rays is IV-converted and amplified by the amplification means. Here, since the current of the photodiode is very small and is affected by the magnetic field of the heating coil 3, the magnetic field of the heating coil 3 is blocked by the first magnetic shielding means 6. Further, the magnetic field is interrupted by the second magnetic shielding means 7 because it goes around from the lower part of the substrate 16 provided with the infrared detecting means 5.

  These magnetic shielding means are made of aluminum or the like which is not easily heated by induction. Further, the zero potential (ground) of the circuit of the infrared detecting means 5 and the first and second magnetic shield means 6 and 7 are connected by a screw 17 so that the potential fluctuation is suppressed, and the infrared detection by turning on and off the high frequency inverter 4 is performed. The output drift of the means 5 is reduced.

  With such a configuration, the infrared detection means 5 operates stably, information of the infrared detection means 5 is input to the temperature detection means 10, and the temperature of the pan 1 can be accurately detected. Thereby, the high frequency inverter 4 is controlled by the control means 11 so that the pan 1 is brought to a predetermined temperature, and the object to be heated can be cooked.

  The reflecting means 8 is composed of a copper pipe, an aluminum pipe, or the like. In order to prevent the mirror state of the inner surface from being deteriorated due to oxidation or the like and to reduce the reflectance, an infrared ray of 2.5 microns or less is used. By applying a coating material, such as an epoxy resin, which is a protective layer with little absorption, the temperature of the pan 1 can be detected stably and accurately. For aluminum, a bright alumite treatment or the like may be used.

  In addition, the infrared detecting means 5 can be provided with a lens on the window material to increase the light receiving area, greatly increase the amount of infrared light incident on the infrared detecting means, improve the S / N ratio, and increase the sensitivity of the pan bottom. The temperature can also be detected accurately.

(Embodiment 2)
FIG. 2 is a block diagram illustrating a configuration of the induction heating cooker according to the second embodiment of the present invention. The induction heating cooker of the present embodiment is different from the first embodiment only in the configuration of the reflection means, and the other parts having the same configuration and operational effects are denoted by the same reference numerals and detailed description thereof is omitted. The explanation will focus on the differences.

  The reflecting means 12 is formed in the shape of a bowl with the top and bottom open, the lower opening having a small diameter is fitted into the infrared detecting means 5, and the upper opening having a large diameter faces the upper side of the first magnetic shielding means.

  In the said embodiment, the reflection means 12 is made into the shape of a mortar-shaped cylinder with the diameter enlarged toward the upper side. Here, the infrared rays entering the infrared detecting means 5 occupy most from the pan bottom in the range of the direct incident field, but some of them are incident obliquely and reflected while being reflected by the reflecting means 12. . FIG. 3A and FIG. 3B are schematic diagrams showing how the infrared rays are incident. The cylindrical reflecting means 8 shown in FIG. 3A is incident on the infrared detecting means 5 after being reflected many times by the reflecting means with respect to the incident infrared rays as shown by the arrows.

  On the other hand, the mortar-shaped reflecting means 12 of FIG. 3 (b) in the present embodiment reflects the radiation from the oblique upper surface of the mortar and emits it to the outside with respect to incident infrared rays as shown by arrows. Therefore, it is not incident on the infrared detecting means 5. Therefore, the temperature at the center of the pan bottom can be detected, and the amount of infrared rays close to the temperature of the heated object in the pan can be detected. In addition, the bottom is not particularly flat, and in the case of a warp pan or the like, it is difficult to be affected by ambient light incident obliquely. As a result, the temperature of the pan 1 can be detected accurately. Thereby, the high-frequency inverter 4 is controlled by the control means 11 so that the pan 1 is brought to a predetermined temperature, and the object to be heated can be cooked.

(Embodiment 3)
FIG. 4 is a block diagram showing the configuration of the induction heating cooker according to the second embodiment of the present invention. The induction heating cooker of the present embodiment is different from the invention of the first embodiment only in the configuration of the magnetic-shielding means, and other parts having the same configuration and operational effects are denoted by the same reference numerals and detailed description thereof is omitted. Omitted and the description will focus on the differences.

  The first magnetic shielding means 13 has an opening 14 through which cooling air flows on the side surface on the lower side arranged below the heating coil 3. Therefore, as shown by the arrow, the cooling air is made to flow into the first magnetic shield means 13 from the one opening 14 by using the air of the fan provided for other purposes in the induction heating cooker, and the other It becomes the structure discharged | emitted from the opening part 14. FIG.

  In the above embodiment, the infrared detection means 5 is connected to the wiring by the connector 18 for output to the temperature detection means 10. For this reason, the connector 18 of the first magnetic shield means 6 is opened by the opening 14. The inside of the induction heating cooker is air-cooled by a fan (not shown) or the like to cool the high-frequency inverter 4 or the like, and the cooling air flows into the first magnetic shield means 13 from one opening 14. It is discharged from the other opening 14 and hits the infrared detection means 5, and the temperature of the infrared detection means 5 can be suppressed to a certain temperature or lower.

  Further, since the other opening 14 is provided on the side opposite to the connector 18 side of the first magnetic shielding means 13, the infrared detection means 5 can be cooled more efficiently by creating a path through which cooling air flows. Since the infrared detection means 5 relatively detects the energy of the difference between its own temperature and the temperature of the object, the temperature difference can be detected more accurately by suppressing its own temperature. If the temperature of the infrared detecting means 5 itself is more constant, the temperature can be detected more accurately. As a result, the pan 1 can be controlled so as to reach a predetermined temperature, and the object to be heated can be cooked smoothly.

(Embodiment 4)
FIG. 5 is an output diagram of the temperature detection means of the induction heating cooker in the fourth embodiment of the present invention. The configuration of the induction heating cooker in the present embodiment is different from the invention of the first embodiment only in the control method of the control means 11, and other parts having the same configuration and operational effects are denoted by the same reference numerals. Detailed description will be omitted, and different points will be described with reference to FIG.

  In the said embodiment, the infrared detection means 5 detects the infrared rays according to the temperature of a pan bottom, as shown in FIG. 5, and the temperature detection means 10 has detected the temperature of the pan bottom. However, the emissivity varies depending on the type of the pan 1, and the absolute value output of the infrared detecting means 5 varies. For example, a black iron pan has an emissivity of about 0.95, whereas a stainless steel pan has an emissivity of about 0.5, and the output varies accordingly.

  In the case of boiling water, the bottom of the pan stabilizes at 100 ° C, so it is sufficient to detect this stable point. However, in the case of watering, the temperature at the bottom of the pan rises rapidly and stops before it reaches an abnormal temperature. If you try to control with the absolute value of this output, it will be affected by emissivity. Therefore, when this change in sensor output, that is, when the inclination is equal to or greater than a certain value, it is determined that the sensor is idling and the heating power is reduced. As a result, an abnormal temperature rise can be prevented, and cooking can be performed without sacrificing the feeling of heat with a fried food.

  In addition, since the infrared energy is increased when the pan bottom is hot, it can be dealt with by switching the amplification factor of the amplification means (not shown) by the switching means (not shown). For example, it is possible to lower the amplification factor assuming that the heating is started at the time of heating. Further, according to the menu, for example, control may be performed so that the amplification factor is switched between cooking at around 100 ° C. such as cooking rice and boiling water, and other than that.

  As described above, the induction heating cooker according to the present invention can accurately detect the temperature of the cooking container without being affected by the magnetic field of induction heating, and thus can be applied to temperature detection techniques in cooking and other induction heating.

The block diagram which shows the structure of the induction heating cooking appliance in Embodiment 1 of this invention. The block diagram which shows the structure of the induction heating cooking appliance in the same Embodiment 2. (A) Schematic diagram of infrared incidence on reflecting means of induction heating cooker to be compared (b) Schematic diagram of infrared incidence on reflecting means of induction heating cooker in Embodiment 2 of the present invention The block diagram which shows the structure of the induction heating cooking appliance in the same Embodiment 3. Output diagram of temperature detection means of induction heating cooker in embodiment 4 The block diagram which shows the structure of the induction heating cooking appliance in a prior art example

Explanation of symbols

1 Pot (cooking container)
2 Top plate 3 Heating coil 5 Infrared detecting means 6, 13 First magnetic shielding means (magnetic shielding means)
7 Second magnetic shield (magnetic shield)
8, 12 Reflecting means 10 Temperature detecting means 11 Control means 14 Opening

Claims (8)

A heating coil for heating the cooking vessel; a top plate for placing the cooking vessel above the heating coil; and an infrared detection means for detecting infrared rays placed under the top plate and emitted from the bottom surface of the cooking vessel. A magnetic shielding means for shielding the magnetic field from the heating coil to protect the infrared detection means from the magnetic field, a temperature detection means for detecting the temperature of the cooking container from the output of the infrared detection means, and an output of the temperature detection means And a control means for controlling the power supplied to the heating coil in accordance with the induction heating cooker in which the magnetic shield means and the zero potential of the infrared detection means are connected. The induction heating cooker according to claim 1, wherein a reflection means is provided in a path from the upper part of the magnetic shielding means to the infrared detection means, located inside the magnetic shielding means. The induction heating cooker according to claim 2, wherein a protective layer that easily transmits infrared rays is formed on the inner surface of the reflecting means. The induction heating cooker according to claim 2 or 3, wherein the reflecting means has a configuration in which an upper diameter is increased. The induction heating cooker according to any one of claims 1 to 4, wherein an opening is provided in a part of the magnetic shield means and the infrared detecting means is cooled by cooling air. The induction heating cooker according to any one of claims 1 to 5, wherein a lens is provided on a window member of the infrared detection means. A heating coil for heating the cooking vessel; a top plate for placing the cooking vessel above the heating coil; and an infrared detection means for detecting infrared rays placed under the top plate and emitted from the bottom surface of the cooking vessel. A magnetic shielding means for shielding the magnetic field from the heating coil to protect the infrared detection means from the magnetic field, a temperature detection means for detecting the temperature of the cooking container from the output of the infrared detection means, and an output of the temperature detection means And a control means for controlling the power supplied to the heating coil in response to the induction heating configured to reduce the power supplied to the heating coil when the amount of change of the infrared detection means exceeds a predetermined value. Cooking device. A heating coil for heating the cooking container, a top plate for placing the cooking container above the heating coil, and an infrared detection means for detecting infrared rays placed under the top plate and emitted from the bottom surface of the cooking container A magnetic shielding means for shielding the magnetic field from the heating coil to protect the infrared detection means from the magnetic field, an amplification means for amplifying the output of the infrared detection means, and the temperature of the cooking container from the output of the amplification means An induction heating cooker comprising temperature detecting means for detecting, control means for controlling the power supplied to the heating coil in accordance with the output of the temperature detecting means, and switching means for varying the amplification factor of the amplifying means.

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