JPS59158088A - Induction heating cooking device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is an induction heating system featuring a magnetic pot detection technology that performs a heating operation when a pot is placed and prevents wasteful power consumption when the pot is not placed. It is related to cooking utensils.

Conventional configuration and problems Induction heating cookers are characterized by extremely rapid thermal response compared to electric heaters or gas because, in principle, the pot mouth body generates heat through eddy currents generated by an alternating magnetic field. Therefore, even if the excitation of the heating coil is temporarily interrupted when the pot to be heated is not placed, and the excitation is restarted after the pot is placed again, the same effect as that of conventional heating is obtained. Therefore, if the equipment heats up and stops in response to raising and lowering the pot during cooking, the efficiency of use will be high and it will be economical. For this reason, magnetic pot detecting means for detecting whether the pot is dry or not has been employed for some time.The most typical example thereof is shown in FIG. At the center of the disc-shaped heating coil 1, a pair of 275 permanent magnets are sandwiched between resin cases 3a and 3b. When the magnet 2 is placed on the pot 5 or the ceramic pot holder 6, the magnet 2 is attracted to the pot 5 and moves upward. 7. At that time, the cases 3a and sb are also pulled up 1. This causes the micro switch 4
The lever (,7'j) is in a state where there is no external force and the contact is reversed.Therefore, by reversing the contact of the microswitch 4, the excitation of the heating coil 1 is controlled and is driven only when the magnetic pot 5 is placed. The problem with this embodiment is that since the magnetization strength of the magnet 2 is limited, it is impossible to increase the weight of the cases 3a and 3b, which reduces the overall weight. Needs to be lighter - 14.

In other words, with regard to microswitches, in addition to the low reliability of mechanical contacts, it is considered that the lever's moving force is small and the self-cleaning effect of the trap contact cannot be ensured sufficiently, and it is possible that a small amount of dust or surface There is a problem that the reliability of the contact becomes poor due to the oxide film5. Figure 2 shows another conventional example (d). A cylindrical resin case 3 is placed in the center of the heating coil 1.A pair of permanent magnets 2a and 2b are housed in the case with their magnetic poles facing each other, and the lower magnet 2b is fixed and the upper magnet 2
a ( is movable. A reed switch 7 is fixed at the center of the two magnets 2 a and 2 b, and when there is no pot 5 ( the magnet 2 a is lowered. In this case, the reed switch The position 7 is positioned where the two magnets 2'a and 2b cancel each other's magnetic fields and the magnetic field strength becomes zero.When the pot 6 is placed on the mounting plate 6, , since only the magnet 2a attracts and moves upward, the position of the reed switch 7 becomes relatively close to the magnet 2b, and the magnetic field is unbalanced, causing the lower magnet 2 to move upward.
Under the influence of the magnetic field b, the reed switch 7 senses the magnetic field and the contacts are reversed, making it possible to control the frequency converter.1 The problem with this conventional example is that the use of the reed switch 7 reduces the reliability of the contacts. However, the alternating magnetic field of the heating coil 1 gathers around the reed switch 7 as shown by the broken line, and the direction of the magnetic field coincides with the high-sensitivity axis of the reed switch 7. , induction addition 4 no.
Sometimes there is a problem that the leet switch 7 malfunctions, so it is necessary to separately install a lutovibe 8 made of non-magnetic metal as shown in the figure, and there are variations in magnetization strength between the ten magnets. There were problems such as the mounting position of the REIT switch 7 was extremely delicate, and f) χii'j adjustment was required.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional problems and provides an induction heating cooker equipped with a magnetic pot detecting means with high operational reliability.

Structure of the Invention The induction heating cooker of the present invention (is
A frequency converter that converts to IJ'(!u frequency, and a disc-shaped heating coil that is connected and excited after it (/c).
A first magnet that absorbs sound and moves along the central axis of the heating coil when a magnetic magnet (1) is placed above the heating coil; one or more second magnets that generate a direct current bias magnetic field orthogonal to the second magnet, and a magnetic field detection element that detects the direct current bias magnetic field generated by the second magnet and controls the drive of the frequency converter. be.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention is shown in FIG. A frequency conversion device 12 connected to a commercial power supply 11 is connected to flow a high frequency current of an ultra-audio frequency whose frequency has been converted into the heating coil 1.On the central axis of the disc-shaped heating coil 1, there is a A first magnet 2, which attracts and moves in response to a magnetic pot 5, is integrated by being inserted into a pair of 11iI thermal resin cases 3a, 3b''c, and vertically moves along the central axis. A pair of second magnets 10a and 10b for biasing a DC magnetic field perpendicular to the center axis is fixed at the lowermost branch of the base 3b. l
In order to detect a magnetic field orthogonal to li, a magnetic field detection element 9 such as a Hall element or a ferromagnetic thin film resistance element is fixed to a branched recess of the case 3b, and its position (for example, the pot 5
The first magnet 2 and the second magnet 10a, 1
0b is absorbed toward the pot mounting plate 6, the second magnet 1
The DC bias magnetic field due to oa and 1ob is fixed so as to coincide with the digit 1 of the 'Ift field detection element 9. .

As is clear from the 41st case (1), when the pot 5 is not placed, the first magnet and the second magnet 10a, 10b are located below the fixed f device of the magnetic field detection element 9. The magnetic field strength is zero, and the output of the magnetic field detection element 9 (・ζ, therefore, the frequency converter 12 (3) is not excited. When the pot 5 is placed on the mounting plate 6, the first and second magnets 2.10a ,1
0b moves upward, and as a result, the DC bias magnetic field moves upward as shown by the broken line in FIG.
start excitation.

Here, as illustrated in the 21st page, the alternating magnetic field generated by the heating coil 1 has only a flat component on the central axis, so magnetic field detection operating with an orthogonal magnetic field as in the embodiment of the present invention There is no influence of malfunction on the element 9. FIG. 5 shows a second embodiment of the present invention. However, case 3b is molded by mixing ferrite powder and resin, and its shape (is the same as that shown in Fig. 3).However, below case 3b there is a pot 50 or (
Case 3 is configured so that a DC bias magnetic field in the opposite direction is applied to the portion facing the magnetic field sensing element 9 in the “no” state.
The ferrite particles contained in b are magnetized. That is, when the magnet 2 is at the bottom as shown in FIG. 2 is on top, another set of magnets 10a, 10b
The magnetic field of p-1-B is biased by. Therefore, the magnetic field detection element 9 only needs to detect the polarity of the DC magnetic field that is sufficiently deeply biased by the four magnets 10a to 1ocl, resulting in extremely stable operation. In addition, since the molded product of ferrite and resin is magnetized at any location, the positional accuracy of the magnetized magnet is high, and it is highly effective for mass production.

As described in detail of the invention, the induction heating cooker I'i in the present invention
(1) Since it uses a magnetic field sensing element and is non-contact, malfunctions due to oxidation/corrosion of contacts, dust, etc. do not occur.

(2) It is easy to absorb the DC bias magnetic field with a strong magnet, and since the magnetic field detection element operates digitally by turning on or off, there is no malfunction due to noise.

(3) Since there is a one-to-one correspondence between the moving distance of the magnet and the moving distance of the magnetic field, the change in the DC bias magnetic field is sheep-sheep, and there is no need to adjust the position of the magnetic field sensing element. .

(4) There is no need to take measures against malfunctions caused by high-frequency magnetic fields from the heating coil.

6゜ has great effects such as

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a schematic configuration showing a conventional induction heating cooker, FIG. 2 is a cross-sectional view of a schematic configuration of another conventional example, and FIG. FIG. 4 is a sectional view of the schematic structure of the cooker, FIG. 4 is an explanatory diagram of the operation of FIG. 3, FIG. 5 is a sectional view of another embodiment of the present invention, and FIG. 6 is an explanatory diagram of the operation of FIG. 5. 1... Heating coil, 2... First magnet, 9
...Magnetic field detection element, 10...Second magnet, 12
...Frequency conversion device. Name of agent: Patent attorney Toshi Isamu Nakao and 1 other person 1st
Figure 2 Figure 3 Figure 4 Strength of early winter field Magnet value I Figure 5 436- Figure 6 Magnet value 1

Claims (2)

[Claims] (1) A frequency converter that converts the commercial power frequency to an ultra-audible frequency, a disc-shaped heating coil excited by the frequency converter, and the central axis of the heating coil when a magnetic pot is placed above the heating coil. A first magnet that attracts and moves along the heating coil, a second magnet that works in conjunction with the first magnet and generates a DC bias magnetic field perpendicular to the central axis of the heating coil, and a DC bias magnetic field generated by the second magnet. An induction heating cooker equipped with a magnetic field detection element that detects and drives and controls a frequency converter. (2) The induction heating cooker according to claim 1, wherein the second magnet is constituted by two sets of magnets so that DC bias magnetic fields in opposite directions are applied in the presence or absence of a pot.