JP2003100433A - Induction heating cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to measure temperature-rise of a switching element with a superior accuracy in an induction heating cooker. SOLUTION: A supporting board 8 protruded toward the switching element 5 side and integrally constituted with a wiring circuit board 1 is installed, and by installing a temperature detecting element 9 at this supporting board 8, the temperature-rise of the switching element can be detected with a superior accuracy by the temperature detecting element 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating cooker capable of accurately detecting the temperature of a switching element which constitutes a high frequency generator.

[0002]

2. Description of the Related Art The structure of a conventional general induction heating cooker is shown in FIG. In the figure, 20 is a wiring board on which a high-frequency generator and the like are arranged. The high-frequency generator includes a rectifier 21 that converts alternating current into direct current, a smoothing capacitor that smoothes the direct current rectified by the rectifier 21, a resonance capacitor (neither is shown), and a switching element 22.

As is well known, the induction heating cooker heats an iron pot or the like of a load by magnetic flux generated by a high frequency current generated from a high frequency generator flowing through a heating coil (not shown). is there. The rectifier 21
Since the switching element 22 generates heat when a high-frequency current is generated, it is generally fixed to a radiator 23 made of aluminum or the like having good thermal conductivity to absorb the heat. Further, the cooling fan 24 sucks the outside air from the intake port 25, blows it to the radiator 23, and discharges it from the exhaust port 26, so that the switching element 22 and the rectifier 21 are not thermally destroyed due to the temperature rise, and the destruction upper limit temperature 150 It has been cooled to below ℃.

In the unlikely event that the cooling fan 24 fails, the switching element 22 is thermally destroyed and a current fuse (not shown) arranged in series in the current path from the commercial AC power source to the high frequency generator is blown. The device has stopped operating.

Recently, as shown in FIG.
A thermistor element 28, which is a chip-shaped surface mounting type temperature detecting element, is arranged near the terminal of the switching element 22 on the back surface of the wiring board 20 on which the copper foil which is the conductor 27 is stretched,
Some of them detect the temperature rise inside the switching element 22.

FIG. 11 shows the temperature change and the operation at this time. In FIG. 11, when heating is initially started at 1500 W, the temperatures of the switching element 22 and the thermistor element 28 are about 9 ° C.
Stable at 0 ° C to 100 ° C. In this state, for example, the intake port 2
When 5 is shielded for some reason and the function of the cooling fan 24 stops, the temperature continues to rise as shown in the figure. When the temperature detected by the thermistor element 28 exceeds 120 ° C., the temperature rise is detected and heating is stopped. The temperature of the switching element 22 at that time is about 140 ° C.

In another example, as shown in FIG. 12, there is an example in which a glass tube-containing thermistor element 28 with a lead wire is arranged on the front side of the wiring board 20 and below the switching element 22, but in this case, As shown in the figure, a heat-resistant sponge-like component 29 that blocks air flow is added to improve the detection accuracy of the thermistor element 28.

[0008]

However, in the conventional induction heating cooker shown in FIG. 10, the thermistor element 28 is attached to the back surface of the wiring board 20 and soldered, so that the switching element 22 is The temperature is detected by detecting the heat transmitted from the inside of the switching element 22 to the lead wire of the terminal and absorbed by the wiring board 20. Therefore, the temperature detected by the cooling air from the cooling fan 24, the cooling of the terminals of the switching element 22 by the air blown to the thermistor element 28, the variation in the mounting of the terminals, etc., causes the detected temperature to be the switching element 22 to be detected. There is a difference of about 20 ° C. from the internal temperature of, and the detection accuracy also varies by about ± 8 ° C.

Therefore, in order to keep the breakdown temperature of the switching element 22 below 150 ° C., the thermistor element 2
The detection temperature of 8 must be suppressed to about 120 ° C. As a result, when a factor that obstructs air supply / exhaust of the cooling fan 24 by suctioning with a cloth or newspaper and blocking the exhaust ports 25, 26 occurs. Alternatively, when the temperature of the air taken in by the cooling fan 24 rises to about 50 ° C. due to hot air in the kitchen,
There is a problem that heating may be stopped when the temperature detected by the thermistor element 28 is exceeded.

Further, in the induction heating cooker shown in FIG.
Even if the windbreak sponge 29 for the wall that blocks the air flow is added, the distance between the switching element 22 and the thermistor element 28 is still large, and there is a problem in that the detection accuracy varies greatly.

The present invention solves the above-mentioned problems. It is possible to detect a temperature rise of a switching element with high accuracy and use it safely, without stopping heating when the cooling effect is slightly lowered, and when the switching element is abnormal. It is an object of the present invention to provide an induction heating cooker in which the operation of the device is surely stopped before being destroyed.

[0012]

In order to achieve the above object, an induction heating cooker according to the present invention comprises a switching element, or a temperature detecting means for detecting the temperature in the vicinity thereof, which is formed integrally with a wiring board. It is installed on a support stand projecting to the side so as to be close to the switching element.

Thus, it is possible to obtain the effect that the temperature of the switching element can be detected more accurately with a simple structure.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 is a heating coil, a high frequency generator comprising a rectifier, a switching element, a capacitor and the like for performing induction heating together with the heating coil, and the high frequency generator. The wiring board to be mounted, and the switching element, or a temperature detecting means for detecting the temperature in the vicinity thereof, the temperature detecting means,
By using an induction heating cooker installed on a support stand that is configured integrally with the wiring board and projects toward the switching element,
The temperature rise of the switching element can be detected more accurately.

According to a second aspect of the present invention, the support base for the wiring board is the induction heating cooker according to the first aspect in which a wall is provided on the windward side of the cooling wind, and thus the influence of the wind is provided. The temperature rise of the switching element can be detected more accurately by reducing the temperature.

According to a third aspect of the present invention, the support base of the wiring board is arranged so that the temperature detecting means is installed near the switching element and on the leeward side of the switching element. By using the induction heating cooker, the influence of the wind can be reduced and the temperature rise of the switching element can be detected more accurately.

According to a fourth aspect of the present invention, the support base of the wiring board is integrally formed with a support portion that supports a radiator for cooling the switching element and the rectifier. By using the induction heating cooker described in
The effect of wind can be reduced without increasing the number of constituent elements, and the temperature rise of the switching element can be accurately detected.

According to a fifth aspect of the present invention, in the wiring board, the conductor and the resin covering the conductor are integrally molded.
By using the induction heating cooker according to any one of 1 above, the support base of the temperature detection element can be easily configured integrally with the wiring board, and the influence of wind can be reduced to increase the temperature of the switching element. It can be accurately detected.

The invention according to claim 6 is a heating coil,
A high-frequency generator configured by a rectifier, a switching element, a capacitor, and the like, which performs induction heating together with this heating coil, a wiring board on which the high-frequency generator is mounted, and the temperature detection that detects the temperature of the switching element or the vicinity thereof. The temperature detection means is an induction heating cooker installed so as to be equal to or lower than the plane height of the wiring board, thereby reducing the influence of wind and increasing the temperature of the switching element with a simple configuration. It can be accurately detected.

The invention according to claim 7 is a heating coil,
A high-frequency generator configured by a rectifier, a switching element, a capacitor, and the like, which performs induction heating together with this heating coil, a wiring board on which the high-frequency generator is mounted, and the temperature detection that detects the temperature of the switching element or the vicinity thereof. The temperature detection means is an induction heating cooker installed so as to be equal to or lower than the upper end height of the wall on the wiring board provided around the means, thereby increasing the height of the wall on the wiring board. The temperature can be made as low as possible, the influence of the wind can be reduced, and the temperature rise of the switching element can be detected more accurately.

The invention according to claim 8 is characterized in that the temperature detecting means is constituted by a glass-sealed type thermistor element with a lead wire, and one end of the terminal is installed in the vicinity of the terminal of the switching element. By using the induction heating cooker according to any one of 1 to 7, the heat conduction from the terminals of the switching element is also used to reduce the influence of wind and detect the temperature rise of the switching element more accurately. Is something that can be done.

[0022]

Embodiments will be described below with reference to the drawings.

(Embodiment 1) In FIGS. 1 to 3, reference numeral 1 is a wiring board integrally formed with a conductor 11 and a resin covering the conductor 11, and a high frequency generator or the like is mounted thereon. The high frequency generator includes a rectifier 2 and a rectifier 2 for converting alternating current into direct current.
Smoothing capacitor 3 for smoothing the direct current rectified by
It is composed of a resonance capacitor 4 and a switching element 5.

As is well known, the induction heating cooker heats the iron pot etc. of the load by the magnetic flux generated by the high frequency current generated from the high frequency generator flowing through the heating coil (not shown). is there. Since the rectifier 2 and the switching element 5 generate heat when a high frequency current is generated, the radiator 6 is generally made of aluminum or the like having good heat conduction.
It is fixed to absorb the heat. Further, the cooling fan 7 sucks the outside air from the intake port 17 provided on the lower surface of the device body, blows it to the radiator 6 and discharges it from the exhaust port 18, so that the switching element 5 and the rectifier 2 are not thermally destroyed due to the temperature rise. The maximum temperature of destruction 15
It is cooled to below 0 ° C.

Reference numeral 8 denotes a support base integrally formed with the wiring board 1, which has a shape protruding toward the switching element 5 side.
The tip is provided with a recess 8a for receiving the glass-sealed type thermistor element 9. That is, the support 8 lifts the thermistor element 9 close to the switching element 5 arranged in contact with the lower surface of the radiator 6. Therefore, the temperature of the switching element 5 can be accurately detected. The thermistor element 9 is the switching element 5,
Alternatively, it constitutes a temperature detecting means for detecting the temperature in the vicinity thereof.

FIG. 8 shows temperature changes and heating operations of the switching element 5 and the thermistor element 9 at this time. As shown in the figure, at the beginning of heating, the temperature of the switching element 5 and the temperature detected by the thermistor element 9 are almost equal, and when the intake port 17 (or the exhaust port 18) is shielded, the temperature of the switching element 5 starts to rise.

The temperature of the switching element 5 is the predetermined temperature 14
When the temperature exceeds 5 ° C, the temperature of the thermistor element 9 exceeds 140 ° C, and heating is stopped at this point.

After that, when the temperature of the switching element 5 decreases due to the stop of the heating, the temperature of the thermistor element 9 follows accurately, and the heating is started again when the temperature decreases to a predetermined temperature.

(Embodiment 2) In the second embodiment of the present invention, as shown in FIGS. 4 and 5, a windbreak wall 10 is provided on the windward side of the recess 8a for receiving the thermistor element 9 of the support 8. Thus, the cooling air for cooling the high frequency generator such as the switching element 9 is prevented from directly hitting the thermistor element 9.

As a result, the thermistor element 9 can detect the temperature of the switching element 5 more accurately.

(Embodiment 3) In the third embodiment of the present invention, as shown in FIGS. 4 and 5 shown in Embodiment 2, the support base 8 of the wiring board 1 and the thermistor element 9 are the switching elements 5 respectively. Is arranged in the vicinity of and in the leeward side of the switching element 5 with respect to the blowing direction of the blowing fan 7. As a result, the temperature rise of the switching element 5 can be detected more accurately without the thermistor element 9 being affected by the wind.

(Embodiment 4) In the fourth embodiment of the present invention, as shown in FIG. 6, a support base 8 for the thermistor element 9 is provided.
Is integrally formed with the support portion 15 for fixing the radiator 6 to the wiring board 1 with the screw 14.

As a result, the support base 8 for the thermistor element 9 is formed.
The strength is increased and the structure is simplified.

(Embodiment 5) In the fifth embodiment of the present invention, as shown in each of the embodiments, the wiring board 1 is formed by integrally molding the conductor 11 and the resin so that a separate member is used. The support base 8 of the thermistor element 9 is configured without any need, and the configuration is simplified.

(Embodiment 6) A sixth embodiment of the present invention is shown in FIG.
Shown in. In the figure, a copper conductor 11 having a thickness of about 0.5 mm
A recess 16 is formed in the resin-made wiring board 1 integrally molded with, and the glass-sealed type thermistor element 9 is installed in the recess 16. That is, the thermistor element 9 is installed so that the height of the thermistor element 9 is less than or equal to the upper end height of the wall on the wiring board 1 provided around the thermistor element 9.

With this configuration, the cooling air does not directly cool the thermistor element 9, so that the switching element 5 can be accurately measured.
Follow the temperature of.

(Embodiment 7) In this embodiment, as shown in FIG. 7, on the windward side of the recess 16 provided in the wiring board 1,
The windshield wall 10 reaching the vicinity of the switching element 5 is provided. This windbreak wall 10 has a recess 1
By installing the thermistor element 9 in 6, the height can be lowered.

With this configuration, the thermistor element 9 can be brought close to the switching element 5, and more accurate temperature detection can be performed.

(Embodiment 8) In this embodiment, as best shown in FIG. 7, the thermistor element 9 is constituted by a glass-sealed type thermistor element with a lead wire, and one end 9a of its terminal is formed. Is installed in the vicinity of the terminal 5a of the switching element 5.

With this structure, the heat conduction from the terminal 5a of the switching element 5 is also utilized to reduce the influence of the wind and to detect the temperature rise of the switching element 5 more accurately.

[0041]

As described above, according to the first to eighth aspects of the invention, the temperature detecting means for detecting the temperature of the switching element or the vicinity thereof can detect the temperature rise of the switching element with high accuracy. Therefore, it is possible to obtain an effect that the user does not easily stop the heating during use and can surely stop the device before the device is destroyed and becomes unusable.

[Brief description of drawings]

FIG. 1 is a plan view of the internal configuration of an induction heating cooker showing a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along the line AA of FIG.

FIG. 3 is a view seen from the direction B in FIG.

FIG. 4 is an enlarged cross-sectional view of a main part in second and third embodiments of the present invention.

FIG. 5 is a view seen from the direction B in FIG.

FIG. 6 is an enlarged cross-sectional view of a main part in a fourth embodiment of the present invention.

FIG. 7 is an enlarged cross-sectional view of a main part in fifth to eighth embodiments of the present invention.

FIG. 8 is a temperature rise characteristic diagram of the switching element and the thermistor element in the first embodiment.

FIG. 9 is a plan view of the internal configuration of a conventional induction heating cooker.

10 is an enlarged cross-sectional view taken along the line AA of FIG.

FIG. 11 is a temperature rise characteristic diagram of a switching element and a thermistor element in a conventional example.

FIG. 12 is an enlarged cross-sectional view showing the configuration of another conventional example.

[Explanation of symbols]

1 wiring board 2 rectifier 3 smoothing capacitors 4 resonance capacitors 5 switching elements 6 radiator 7 Cooling fan 8 support 9 Thermistor element (temperature detection element) 10 windbreak 11 conductors 15 Support 17 Inlet 18 Exhaust port

Claims (8)

[Claims] 1. A high frequency generator comprising a heating coil, a rectifier, a switching element, a capacitor and the like for performing induction heating together with the heating coil, a wiring board on which the high frequency generator is mounted, the switching element, or A temperature detecting means for detecting the temperature in the vicinity thereof,
The said temperature detection means is an induction heating cooker installed in the support stand which is comprised integrally with a wiring board and protrudes to the switching element side. 2. The induction heating cooker according to claim 1, wherein the support base of the wiring board is provided with a wall located on the windward side of the cooling air. 3. The induction heating cooker according to claim 1, wherein the support base of the wiring board is arranged such that the temperature detecting means is installed near the switching element and on the leeward side of the switching element. 4. The induction heating cooker according to claim 1, wherein the support base of the wiring board is integrally formed with a support portion that supports a radiator for cooling the switching element and the rectifier. . 5. The induction heating cooker according to claim 1, wherein the wiring board is integrally formed of a conductor and a resin covering the conductor. 6. A high frequency generator comprising a heating coil, a rectifier, a switching element, a capacitor and the like for performing induction heating together with the heating coil, a wiring board on which the high frequency generator is mounted, the switching element, or A temperature detecting means for detecting the temperature in the vicinity thereof,
The induction heating cooker in which the temperature detecting means is installed so as to be below the plane height of the wiring board. 7. A high frequency generator including a heating coil, a rectifier, a switching element, a capacitor and the like for performing induction heating together with the heating coil, a wiring board on which the high frequency generator is mounted, the switching element, or A temperature detecting means for detecting the temperature in the vicinity thereof,
In the induction heating cooker, the temperature detecting means is installed so as to be below the height of the upper end of the wall on the wiring board provided around the temperature detecting means. 8. The temperature detecting means is constituted by a glass-sealed type thermistor element with a lead wire, and one end of the terminal is installed near the terminal of the switching element. Induction heating cooker according to.