JP5033728B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to an induction heating cooker that induction-heats a load such as a pan placed on a top plate by a heating coil provided in the main body, and in particular, an induction heating cooker that can accurately detect the temperature of the load. It is about.

  In this type of conventional induction heating cooker, in order to detect the temperature of a load such as a pan placed on the top plate, a temperature sensor is disposed on or in the vicinity of the heating coil. The temperature of the pan or the like was detected via the top plate, and the output of the heating coil was controlled.

  The temperature sensor is connected to a thermistor body with a lead wire (jumet wire) made of a magnetic metal having a wire diameter of 0.3 mm, and the thermistor body and the lead wire are sealed with glass having the same expansion coefficient as the lead wire. It consists of a stopped glass-sealed thermistor, and the lead wire is connected to the control unit of the heating coil via a lead wire.

  In such a glass-sealed thermistor, a jumet wire made of a magnetic metal is induction-heated under the influence of a magnetic field generated from a heating coil, and the heat is transmitted to the thermistor body, so that the thermistor body generates heat. Arise.

  The problem is that when the material of the pan such as the load is a magnetic material such as iron, the load is heated by a high-frequency magnetic field of about 21 KHz, so that the jumet wire is less affected by induction heating, and the thermistor The temperature rise of the main body is also within an allowable range in which temperature correction is possible, and the temperature sensor can accurately measure the temperature of the load.

  However, if the material of the pan such as the load is a non-magnetic material such as aluminum, the load is heated by a strong high-frequency magnetic field of 60 KHz or more, so the jumet wire is also strongly affected by induction heating and generates heat. The heat raises the temperature of the thermistor body. For this reason, the thermistor body exceeds the allowable range in which the temperature can be corrected, which causes a problem that the temperature of the load cannot be measured accurately.

  Therefore, in order to prevent the thermistor body from generating heat, the thermistor body is formed in a cylindrical shape, and the central axis of the cylindrical shape is arranged so as to be substantially perpendicular to the magnetic field generated by the heating coil, so that the induction heating is difficult. It is shown in Patent Document 1.

JP 2001-267055 A

  However, in the above-mentioned Patent Document 1, it is necessary to arrange the thermistor body in a cylindrical shape and to arrange the central axis of the cylindrical shape so as to be substantially perpendicular to the magnetic field generated by the heating coil. Since the arrangement position is limited, there is a problem that it is difficult to arrange the temperature sensor at an optimal position for detecting the temperature of the load on or near the heating coil.

  This invention solves such a conventional subject, and it aims at providing the induction heating cooking appliance which makes temperature sensor a structure which is hard to carry out induction heating, and enables more accurate temperature detection.

The present invention has been made to solve the above-described problems. In claim 1, a top plate on which a load made of a magnetic material or a non-magnetic material is placed, and the load provided below the top plate is provided. In an induction heating cooker provided with a heating coil for induction heating and a temperature sensor provided in the vicinity of the heating coil for detecting the lower surface temperature of the top plate, the temperature sensor seals the thermistor element with glass. 15mm and a thermistor body, and connected to said thermistor element and a lead wire made of dumet wire drawn from the same direction of the thermistor body, 0.05 mm to 0.1 mm and wire diameter of the lead wire, the length The temperature sensor is provided in the gap between the upper surface of the heating coil and the lower surface of the top plate, and before facing the upper surface of the heating coil. The length of the lead wire is obtained by a 10mm or less.

  Since the induction heating cooker of the present invention is configured as described above, the lead wire of the temperature sensor is less likely to be heated due to the influence of the high frequency magnetic field, and as a result, the temperature sensor is not affected by the induction heating. The temperature of the pan can be accurately detected.

  In addition, a temperature sensor can be disposed at a more optimal position for detecting the temperature of the load.

  An embodiment of the present invention will be described below with reference to FIGS.

  FIG. 1 is an external perspective view of an induction heating cooker. In FIG. 1, 1 is a main body of an induction heating cooker. Reference numeral 2 denotes a top plate made of crystallized glass having high heat resistance, which is horizontally disposed on the upper surface of the main body 1 and mounts a metal load such as a pot 50 made of a magnetic material such as iron or a non-magnetic material such as aluminum. Is.

  FIG. 3 shows a heating unit, which is composed of a heating coil 11 which will be described later. The heating coil 11 is arranged at three locations on the upper right and left and rear sides in the main body 1 below the top plate 2 and placed on the top plate 2. The pot 50 is heated.

  An operation unit 7 corresponding to each heating unit 3 is provided on the upper surface on the front side of the top plate 2, and the energization state of the heating unit 3 is set and operated. 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 unit 3.

Reference numeral 4 denotes an air inlet that opens upward at the rear portion of the main body 1 and is an opening for taking cooling air into a control board (not shown) inside the main body 1.

Reference numeral 5 denotes an exhaust port, which is an opening portion that is opened upward at the rear portion of the main body 1 like the intake port 4. In this embodiment, the intake port 4 is disposed on the right side of the rear portion of the main body 1 and the exhaust port 5 is disposed on the left side. Reference numeral 6 denotes a grill heating unit provided at the left front portion of the main body 1.

  2 is a top view of the heating coil 11, and FIG. 3 is an AA longitudinal sectional view of the heating coil 11 of FIG.

  In the figure, the heating coil 11 constituting the heating unit 3 is formed in an annular shape, has a space part 11d at the center, and is divided into two parts, an outer coil 11a and an inner coil 11b. A gap 11c is provided between the inner coils 11b.

  The heating coil 11 is installed on a coil base 16 provided in the main body 1 below the top plate 2, and a plurality of bar-shaped ferrites 18 are radially arranged below the coil base 16. The magnetic flux generated from the magnetic field spreads below the coil base 16 so that the electronic component is not easily affected by noise caused by the magnetic lines of force in the vicinity of the metal or electronic component in the vicinity.

  The coil base 16 on which the heating coil 11 is installed is urged toward the top plate 2 by a plurality of springs (not shown), and the heating coil 11 is configured to be substantially parallel to the top plate 2. .

  A first temperature sensor 13 is provided in the space 11 d at the center of the heating coil 11. A second temperature sensor 17 attached to the gap spacer 15 is provided on the winding of the outer coil 11a.

  The gap spacer 15 is for maintaining a constant gap between the pan 50 placed on the upper surface of the top plate 2 and the heating coil 11, and is supported by a support member 15 a attached to the outer peripheral edge of the coil base 16. The coil base 16 is provided from the outer periphery of the upper surface toward the center side.

  4 is an external perspective view of the first temperature sensor 13, FIG. 5 is a longitudinal sectional view of the first temperature sensor 13, FIG. 6 is an external perspective view of the second temperature sensor 17, and FIG. It is a longitudinal cross-sectional view of the temperature sensor 17 of FIG.

  In the figure, each of the first temperature sensor 13 and the second temperature sensor 17 is a case 20 using a ceramic material at a portion in contact with the top plate 2, and a thermistor element is sealed with glass inside. The glass-sealed thermistor main body 23 configured as described above is housed and fixed with an inorganic filler 24.

  The thermistor body 23 is connected to a lead wire 27 composed of a jumet wire 26 having substantially the same thermal expansion coefficient as that of the glass sealing the thermistor element. Is connected to the lead wire 22 by a connector 21 and connected to a control board (not shown) inside the main body 1.

  The dumet wire 26 has a structure in which a copper layer or a copper-containing alloy layer is provided around an iron-nickel core wire, and a cuprous oxide film is provided on the surface of the copper layer or the copper-containing alloy layer.

  The first temperature sensor 13 is attached so that the upper surface of the cylindrical case 20 is in close contact with the lower surface of the top plate 2, and measures the temperature of the lower surface of the top plate 2 above the center of the heating coil 11.

  As shown in FIGS. 3 and 5, the dumet wire 26 of the first temperature sensor 13 has a wire diameter φ of 0.07 mm, a length of 15 mm or less, and straight to the space portion 11d at the center of the inner coil 11b. It is extended downward, connected to the lead wire 22 by the connection terminal 21, and connected to the control board by the lead wire 22.

  FIG. 8 is an enlarged view of the second temperature sensor 17. In the figure, the second temperature sensor 17 is attached to the gap spacer 15 on the winding of the outer coil 11a on the outer peripheral side of about 10 mm from the inner end of the annular outer coil 11a.

  Since the coil base 16 is urged by a spring (not shown) in the direction of the top plate 2 in the second temperature sensor 17, the case 20 of the second temperature sensor 17 attached to the gap spacer 15 is the top plate. 2 is in close contact with the lower surface of 2 and the temperature of the lower surface of the top plate 2 is measured.

As shown in FIGS. 7 and 8, the dumet wire 26 of the second temperature sensor 17 has a wire diameter φ of 0.07 mm, a length of 15 mm or less, and the upper surface of the outer coil 11 a and the top plate 2. The length of the portion facing the upper surface of the outer coil 11a of the dumet wire 26 wired in the gap between the lower surface and the lower surface of the outer coil 11a is set to 10 mm or less . And connected to the lead wire 22 by the connector 21 and connected to the control board by the lead wire 22.

  FIG. 9 shows a configuration in which the load is made of an iron pan 50 when the diameters φ of the jumet wires 26 of the first temperature sensor 13 and the second temperature sensor 17 are 0.3 mm and 0.07 mm in the configuration shown in FIG. The characteristic view for demonstrating the temperature rise of the dumet wire 26 when it supplies with electricity to the heating coil 11 is shown.

  FIG. 10 shows the first and second temperatures when the load is the iron pan 50 and the aluminum pan 50 in the configuration shown in FIG. The characteristic view for demonstrating the detection temperature rise of the sensors 13 and 17 is shown.

  As shown in FIG. 9, when the heating coil 11 is energized, the dumet wire 26 is induction-heated due to the influence of the magnetic field generated from the heating coil 11, and the temperature of the dumet wire 26 rises due to the heat generation.

  The temperature rise value of the jumet wire 26 is smaller than that of the 0.07 mm wire diameter of the jumet wire 26 compared to that of 0.3 mm.

  In such a temperature sensor using the jumet wire 26, the thermistor body 23 is fixed with a case 20 using a ceramic material and an inorganic filler 24 inside the case 20. The heat generated by is transmitted to the filler 24 and the case 20.

  Therefore, the heat generation of the jumet wire 26 that affects the actual thermistor body 23 is about 8 ° C. when the wire diameter φ of the jumet wire 26 is 0.3 mm and the load is an iron pan 50 as shown in FIG. . If it is a temperature rise value of this level, it is an allowable temperature from the accuracy of heating control of the pan 50.

  However, when heating the aluminum pan 50, the magnetic field generated by the heating coil 11 is stronger than the magnetic field heating the iron pan 50. When the amount of heat generation increases and the diameter of the jumet wire 26 is 0.3 mm, the temperature rise value becomes large, and the temperature of the pot 50 cannot be accurately detected.

  Therefore, when using a temperature sensor that is affected by induction heating, it is not possible to detect the temperature of the pan 50 with high accuracy unless a place where the strength of the magnetic field generated by the heating coil 11 is weak is selected and installed. The installation location of the temperature sensor is limited.

  Therefore, as shown in FIG. 10, by setting the diameter φ of the jumet wire 26 to 0.1 mm or less, the temperature rise value of the temperature sensor is 10 ° C. in both the iron pan 50 and the aluminum pan 50. The temperature can be set to an acceptable temperature from the accuracy of the heating control of the pot 50, and more accurate temperature detection can be performed.

As described above, in this embodiment, the diameter φ of the dumet wire 26 that is the lead wire of the first temperature sensor 13 and the second temperature sensor 17 is 0.1 mm or less, preferably the problem of its own resistance, lead wire The first temperature sensor 13 and the second temperature sensor 17 are provided in the vicinity of the heating coil 11 by setting the thickness to about 0.05 mm to 0.1 mm in consideration of the problem of connection with the heater 22. Moreover, it can be made hard to receive the influence of the magnetic field of the heating coil 11, and they were confirmed also by experiment.

  Further, the shorter the length of the dumet wire 26, the less affected by the induction heating of the heating coil 11 and the less the heat transmitted to the thermistor body 23. In the case of the first temperature sensor 13, the heating coil 11 Since the upper surface of the cylindrical case 20 is closely attached to the lower surface of the top plate 2 in the central space portion 11d, if the length is 15 mm or less as shown in FIG. As a result, the temperature sensor can reduce the influence of induction heating and accurately detect the temperature of the pan.

  Further, in the case of the dumet wire 26 of the second temperature sensor 17, as shown in FIG. 8, the length is 15 mm or less, and the gap between the upper surface of the outer coil 11a and the lower surface of the top plate 2 is used. If the length of the upper surface of the outer coil 11a of the jumet wire 26 wired to the strong magnetic field is 10 mm or less, the lead wire is less likely to be heated by the influence of the high frequency magnetic field, and as a result, The temperature sensor can reduce the influence of induction heating, and can accurately detect the temperature of the pan.

  Thus, both the first temperature sensor 13 for detecting the temperature of the lower surface of the top plate 2 at the center of the heating coil 11 and the second temperature sensor 17 for detecting the temperature of the lower surface of the top plate 2 by the upper surface of the outer coil 11a. The temperature of the pot 50 as a load can be detected with high accuracy.

  In particular, it is possible to accurately detect the temperature of the pan that has been relatively difficult to measure with high accuracy and is relatively hot just above the outer coil 11a.

  In the present embodiment, the shape of the heating coil 11 is divided into the outer coil 11a and the inner coil 11b. However, the present invention is not particularly limited to this. For example, the structure of the heating coil which is not divided | segmented into two may be sufficient.

It is an external appearance perspective view of the induction heating cooking appliance which shows one Example of this invention. It is a top view of a heating coil. It is heating coil AA longitudinal cross-sectional view of FIG. It is an external appearance perspective view of a 1st temperature sensor. It is a longitudinal cross-sectional view of a 1st temperature sensor. It is an external appearance perspective view of a 2nd temperature sensor. It is a longitudinal cross-sectional view of a 2nd temperature sensor. It is an enlarged view of a 2nd temperature sensor. It is a characteristic view for demonstrating the temperature rise of a Jumet line. It is a characteristic view for demonstrating the detection temperature rise of a temperature sensor.

Explanation of symbols

2 Top plate 11 Heating coil 13 First temperature sensor 17 Second temperature sensor 27 Lead wire

Claims (1)

A top plate on which a load made of a magnetic material or a non-magnetic material is placed; a heating coil provided under the top plate for inductively heating the load; and a lower surface temperature of the top plate provided in the vicinity of the heating coil In an induction heating cooker equipped with a temperature sensor for detecting
The temperature sensor includes a thermistor body sealing the thermistor element of glass, connected to said thermistor element and a lead wire made of dumet wire drawn from the same direction of the thermistor body, the wire diameter of the lead wire 0.05mm to 0.1mm, and the length is 15mm or less,
The induction heating cooker characterized in that the temperature sensor is provided in a gap between the upper surface of the heating coil and the lower surface of the top plate, and the length of the lead wire facing the upper surface of the heating coil is 10 mm or less .

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