JP2001257067A - Induction heating cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction heating cooker that can display the failure when one system of temperature detecting element or temperature detecting circuit has failed and prevents abnormal overheating of a load. SOLUTION: The cooker is equipped with a second temperature detecting means 27 and a temperature over-rising preventing means 28, by which it can prevent over-rising of temperature of a load 24 even if a first temperature detecting means 25 or a temperature control means 26 has failed. It is also equipped with a temperature abnormality detecting means 29, and by checking the 'on' time preset by an 'on' time setting means 22 and the input power to the inverter 13, it can detect and display the abnormality when the first temperature detecting means 25 or the temperature control means 26 has failed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an induction heating cooker.

[0002]

2. Description of the Related Art In recent years, an induction heating cooker for inducing an eddy current at the bottom of a load pan by using a high-frequency magnetic field for heating has attracted attention as a clean, safe and highly heat-efficient cooking means.

Hereinafter, a conventional induction heating cooker will be described with reference to FIG. As shown in FIG. 4, 1 is a commercial power supply, 2 is an inverter for converting the commercial power supply to a high-frequency current, 3 is a control circuit for controlling the inverter 2 and the like, 4 is a power supply circuit for supplying power to the control circuit, 5 is Current fuse,
6 is a first temperature detecting means, 7 is a second temperature detecting means, 8
Is the load.

[0004] The operation of the induction heating cooker configured as described above will be described below. The control circuit 3 drives the inverter 2 to convert the commercial power supply 1 into a high-frequency current and heat the load 8 by induction. The power supply circuit 4 converts the commercial power supply 1 into a DC power supply and supplies it to the control circuit 3. When the short-circuit fault occurs in the inverter 2, the current fuse 5 is blown to prevent the overcurrent from continuing to flow through the inverter 2.

The first temperature detecting means 6 detects the temperature of the load 8 and stops the input to the inverter 2 when the detected temperature exceeds a predetermined temperature T1, so that the second temperature is detected. The means 7 detects the temperature of the load 8 as a backup when the first temperature detecting means 6 fails, and inputs the input to the inverter 2 when the detected temperature exceeds T2 which is a temperature setting higher than T1. Has stopped.

[0006]

However, in the above-mentioned conventional configuration, even if the first temperature detecting means 6 fails, the user is not aware of the failure, and the load is higher than when the first temperature detecting means 6 is operating normally. There was a problem that the temperature of No. 8 became high.

[0007] The present invention has been made to solve the above-mentioned problems, and a first aspect is as follows.
It is an object of the present invention to provide an induction heating cooker capable of displaying an abnormality when the temperature detecting means has failed.

[0008]

To achieve the above object, the present invention provides an inverter including a switching element for converting a commercial power supply to a high-frequency current, an on-time setting means for setting an on-time of the switching element, Input detecting means for detecting an input to the inverter; first and second temperature detecting means for detecting a temperature of the load; and an input to the inverter according to the temperature of the load detected by the first temperature detecting means. A temperature control means for controlling an input, and an output of the on-time setting means when the temperature detected by the second temperature detection means becomes equal to or higher than a predetermined temperature at which the temperature control means stops input to the inverter. An excessive temperature rise prevention means for stopping a signal or converting the signal into a minimum on-time; and a failure of the first temperature detection means or the temperature control means and the excessive temperature rise prevention means It is obtained by the structure having the temperature abnormality detection means for performing determination abnormally displayed in response to an input detected by the ON time and the input detecting means set by the on-time control means that it has created.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 is characterized in that, in addition to the first temperature detecting means and the temperature controlling means, the temperatures detected by the second temperature detecting means and the second temperature detecting means are detected by the temperature controlling means. An over-temperature prevention means for stopping an output signal of the on-time setting means when the temperature becomes equal to or higher than a predetermined temperature for stopping the input to the inverter or converting the output signal into a minimum on-time; Alternatively, the load temperature can be suppressed by the second temperature detecting means and the over-temperature preventing means as a backup when the temperature control means fails, and the temperature can be reduced by the failure of the first temperature detecting means or the temperature controlling means. By providing a temperature abnormality detecting means for judging that the excessive rise prevention means has been activated according to the ON time set by the ON time control means and the input detected by the input detecting means and displaying an abnormality, the first temperature Knowledge means or temperature control means in which it can perform can also fault indicator detected by the general components of the induction heating cooker that has failed overheat protection means has operated.

[0010] The invention according to claim 2 is provided with a load detecting means for heating at a predetermined cycle for a predetermined time to confirm the presence or absence of the load when the load temperature is high and the input to the inverter is stopped. Therefore, even if the load is moved and the load is moved to a non-load state when the temperature of the load is high and the input to the inverter is stopped, the presence or absence of the load is detected by performing heating for a predetermined time at a predetermined cycle. be able to. Further, when the abnormal state determined according to the on-time set by the on-time control means and the input detected by the input detection means continues for a predetermined time or more for heating by the load detection means, the first temperature detection means Alternatively, the first and second temperature detecting means detect that the temperature control means is operating normally by judging that the temperature control means has failed and the excessive temperature rise preventing means has operated. It is possible to prevent the temperature abnormality detecting means from malfunctioning during heating by the load detecting means when the overheating preventing means operates due to an overshoot due to a delay in temperature transmission between the temperature and the load temperature.

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

(Embodiment 1) A first embodiment of the present invention will be described with reference to FIG. As shown in FIG.
1 is a commercial power supply, 12 is a rectifier for converting the commercial power to DC, 13 is an inverter for turning on and off the switching element 13a to convert the DC rectified by the rectifier 12 into a high-frequency current, 21 is driving means for driving the switching element 13a, 22, on-time setting means for setting the on-time of the switching element 13a; 23, input detection means for detecting an input to the inverter 13; 24, a load; 25, first temperature detection means for detecting the temperature of the load 24; 26 is a temperature control means for increasing or decreasing the input to the inverter 13 according to the temperature detected by the first temperature detection means 25, 27 is a second temperature detection means for detecting the temperature of the load 24, and 28 is a second temperature The temperature at which the output signal of the on-time setting means 22 is stopped or converted to the minimum on-time when the temperature detected by the detecting means 27 exceeds a predetermined temperature. Noboru prevention means 29 is a temperature abnormality detecting means for detecting a temperature abnormality at the input to the on-time setting value and the inverter 13.

The operation of the induction cooking device configured as described above will be described below. Drive means 21
Drives the switching element 13a with the on-time set by the on-time setting means 22, converts the DC rectified from the commercial power supply 11 by the rectifier 12 into a high-frequency current, and heats the load 24 such as a pan. Since the inverter 13 has such a characteristic that the longer the on-time of the switching element 13a is, the larger the input to the inverter 13 is, the on-time setting means 22 starts the setting from the state where the on-time of the switching element 13a is short. And gradually increase the on-time until the input detected by the input detection means 23 becomes a desired input,
For most loads, the desired input is reached before the on-time that can be set by the on-time setting means 22 reaches the maximum value. Depending on the material of the load 24 and the like, the on-time may reach the maximum value, but an input substantially close to a desired input can be obtained.

The first temperature detecting means 25 uses a load 24
When the temperature detected by the first temperature detecting means 25 exceeds 230 ° C., a heating stop signal is output from the temperature control means 26 to the on-time setting means 22, and the on-time setting means 22 outputs zero on-time. That is, a signal for stopping the driving of the switching element 13a is output to the driving unit 21, and the heating of the load 24 is stopped. When the temperature detected by the first temperature detecting means 25 becomes 230 ° C. or lower, the heating stop signal output from the temperature control means 26 to the on-time setting means 22 is released, and the heating of the load 24 is restarted. First temperature detecting means 2
5 or when the temperature of the load 24 rises due to the failure of the temperature control means 26, if the temperature detected by the second temperature detection means 27 exceeds 260 ° C. The on-time setting signal output to the driving means 21 is converted into a signal for stopping the heating of the load 24 to prevent the load 24 from overheating.

At this time, the input to the inverter 13 is 0 W
Therefore, the input detected by the input detection unit 23 is also 0 W
Becomes Therefore, since the input to the inverter 13 does not reach the desired input, the ON time set by the ON time setting means 22 reaches the maximum value. In the temperature abnormality detecting means 29, when the state where the input to the inverter 13 is 200 W or less continues for 3 seconds or more when the ON time reaches the maximum value, the excessive temperature rise preventing means 28 operates. For example, it is determined that the first temperature detecting means 25 or the temperature control means 26 has failed, and an abnormal display is performed. As described above, the failure of the first temperature detecting means 25 or the temperature control means 26 can be easily detected by using the on-time setting means 22 and the input detecting means 23 which are general components of the induction heating cooker. it can.

As described above, according to the present embodiment, the provision of the second temperature detecting means 27 and the excessive temperature rise preventing means 28 allows the first temperature detecting means 25 or the temperature control means 26 to be broken even if it fails. The temperature of the load 24 can be prevented from rising excessively, and the temperature abnormality detecting means 29 is provided, and the ON time set by the ON time setting means 22 and the input to the inverter 13 are checked. Alternatively, a failure of the temperature control means 26 can be detected and an abnormality display can be performed.

(Embodiment 2) Next, a second embodiment of the present invention will be described with reference to FIG. As shown in FIG. 2, 11 is a commercial power supply, 12 is a rectifier for converting the commercial power to DC, 13 is an inverter for turning on and off the switching element 13a to convert the DC rectified by the rectifier 12 into a high-frequency current, and 21 is a switching element. Drive means for driving the switching element 13a; on-time setting means 22 for setting the on-time of the switching element 13a; 23, input detection means for detecting an input to the inverter 13; 24, a load;
The first temperature detecting means 26 for detecting the temperature of the inverter 4 corresponds to the temperature detected by the first temperature detecting means 25.
Temperature control means for increasing / decreasing the input to 3; 27, a second temperature detection means for detecting the temperature of the load 24; 28, which is turned on when the temperature detected by the second temperature detection means 27 exceeds a predetermined temperature. Temperature rise prevention means for stopping the output signal of the time setting means 22 or converting the output signal to the minimum ON time; 29, a temperature abnormality detection means for detecting an abnormal temperature based on the ON time set value and the input to the inverter 13; This is a load detecting means for detecting the presence or absence of the load 24 while outputting a signal for stopping the input to the inverter 13 from the means 26.

The operation of the induction cooking device configured as described above will be described below with reference to FIG. The driving means 21 drives the switching element 13a for the ON time set by the ON time setting means 22,
Is converted into a high-frequency current by the rectifier 12 to heat a load 24 such as a pan. In addition, this inverter 13
Has the characteristic that the longer the on-time of the switching element 13a, the larger the input to the inverter 13 is.
The on-time setting means 22 starts the setting in a state where the on-time of the switching element 13a is short, and the input detecting means 23
Is the desired input (in this embodiment, 2k
The on-time is gradually increased until W), and reaches 2 kW before reaching the maximum value of the on-time that can be set by the on-time setting means 22 at most loads. Depending on the material of the load 24 and the like, the on-time reaches the maximum value at less than 2 kW, but an input almost equal to 2 kW can be obtained.

The first temperature detecting means 25 uses a load 24
When the temperature detected by the first temperature detecting means 25 exceeds 230 ° C., a heating stop signal is output to the on-time setting means 22, and the on-time setting means 22 turns on the zero time, that is, the switching element 13a. A signal for stopping the driving is output to the driving means 21, and the heating of the load 24 is stopped. The induction heating cooker cannot detect the presence or absence of the load 24 unless heating is performed.
While the heating is stopped at 6, as shown in FIG.
If the stop of heating for 2 seconds is continued, an instruction of a load detecting operation for heating at 500 W for 2 seconds is sent from the load detecting means 30 to the on-time setting means 22 to detect the presence or absence of a load. When the temperature detected by the first temperature detecting means 25 becomes 230 ° C. or lower, the heating stop signal output from the temperature control means 26 to the on-time setting means 22 is released, and the heating of the load 24 is restarted.

When the first temperature detecting means 25 or the temperature control means 26 fails and the temperature of the load 24 rises,
When the temperature detected by the second temperature detecting means 27 exceeds 260 ° C., the overheating preventing means 28 stops the heating of the load 24 by outputting the on-time setting signal output from the on-time setting means 22 to the driving means 21. The load is converted into a signal to prevent the temperature of the load 24 from rising excessively. At this time, since the input to the inverter 13 is 0 W, the input detected by the input detecting means 23 is naturally 0 W. Therefore, since the input to the inverter 13 does not reach the desired input, the ON time set by the ON time setting means 22 reaches the maximum value. However, even if the first temperature detecting means 25 and the temperature controlling means 26 are normal as shown in FIG.
There is a temperature difference due to a temperature transmission delay in the detected temperatures of the temperature detecting means 25 and 27, and thus the detected temperatures of the first and second temperature detecting means 25 and 27 are over after the heating is stopped by the temperature controlling means 26. A situation in which the overheating prevention means 28 operates by shooting and rising may occur. At this time, even if heating is performed by the load detecting means 30 to detect the presence or absence of the load 24, the heating is stopped by the excessive temperature rise preventing means 28, so that the ON time is the maximum value for two seconds and is input to the inverter 13a. Is 0W.

Therefore, in the temperature abnormality detecting means 29, when the ON time reaches the maximum value, the state in which the input to the inverter 13 is 200 W or less is 3 seconds or more longer than the heating time of the load detecting means 30 of 2 seconds. If you continue,
It is determined that the first temperature detection means 25 or the temperature control means 26 has failed and the excessive temperature rise prevention means 28 has operated, and an abnormal display is performed. As described above, the on-time setting means 22 and the input detection means 2 which are general components of the induction heating cooker are used.
The failure of the first temperature detecting means 25 or the temperature control means 26 can be easily detected by utilizing the information processing device 3.

As described above, according to this embodiment, the presence of the load 24 can be detected even when the temperature of the load 24 is high and the heating is stopped by providing the load detecting means 30. Further, the provision of the second temperature detecting means 27 and the excessive temperature rise preventing means 28 can prevent the temperature of the load 24 from excessively rising even if the first temperature detecting means 25 or the temperature control means 26 fails. The first temperature detection unit 25 or the temperature control unit is provided by checking the ON time set by the ON time setting unit 22 and the input to the inverter 13 longer than the load detection operation time. 26 can be detected and an abnormal display can be performed.

It is not necessary for the load detecting means to have a constant heating time at a constant heating repetition cycle, and the heating operation may be performed intermittently, and the repetition cycle or the heating time may be arbitrarily changed. In this case, the temperature abnormality detection means detects the failure of the first temperature detection means or the temperature control means by continuously checking the ON time and the input for the maximum heating time set by the load detection means, and displays an abnormality. Should be performed.

[0024]

As described above, according to the first aspect of the present invention, in addition to the first temperature detecting means and the temperature controlling means, the temperature is detected by the second temperature detecting means and the second temperature detecting means. When the temperature becomes equal to or higher than a predetermined temperature at which the input to the inverter is stopped by the temperature control means, the output signal of the on-time setting means is stopped or the over-temperature prevention means for converting the output signal to the minimum on-time is provided. As a backup when the first temperature detecting means or the temperature control means fails, the temperature of the load can be suppressed by the second temperature detecting means and the excessive temperature rise preventing means, and the first temperature detecting means or the temperature control means can be suppressed. A temperature abnormality detecting means for judging that the means has failed and the overheating prevention means has been activated according to the ON time set by the ON time control means and the input detected by the input detecting means and displaying an abnormality is provided. Thus, it is possible to detect that the first temperature detecting means or the temperature control means has failed and the excessive temperature rise preventing means has operated by using a general component of the induction heating cooker without providing a dedicated detecting circuit, and also displays an abnormality display. And a highly safe induction heating cooker can be provided.

Further, according to the second aspect of the present invention, load detection for performing heating for a predetermined period of time for a predetermined period to confirm the presence or absence of a load when the temperature of the load is high and the input to the inverter is stopped. By providing the means, even if the load is moved while the load temperature is high and the input to the inverter is stopped, and the load goes into a no-load state, the load is heated for a predetermined period at a predetermined cycle to thereby reduce the load. Presence can be detected,
Further, when the abnormal state determined according to the on-time set by the on-time control means and the input detected by the input detection means continues for a predetermined time or more for heating by the load detection means, the first temperature detection means Alternatively, it is determined that the temperature control means has failed and the excessive temperature rise prevention means has operated, so that the fact that the first temperature detection means or the temperature control means has failed and the excessive temperature rise prevention means has operated is designated as a special purpose. It is possible to provide a reasonable and highly safe induction heating cooker that can be detected without erroneous detection by a general component of the induction heating cooker without providing a detection circuit and can display an abnormality.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of an induction heating cooker according to a first embodiment of the present invention.

FIG. 2 is a circuit block diagram of an induction heating cooker according to a second embodiment of the present invention.

FIG. 3 is a characteristic diagram of the induction heating cooker with respect to time.

FIG. 4 is a circuit block diagram of a conventional induction heating cooker.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 13 Inverter 13a Switching element 21 Driving means 22 On-time setting means 23 Input detecting means 25 First temperature detecting means 26 Temperature controlling means 27 Second temperature detecting means 28 Overheat prevention means 29 Temperature abnormality detecting means 30 Load detecting means

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaji Kamihara 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 72) Inventor Kenji Hattori 1006 Kadoma Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Masaru Kawabe 1006 Kadoma Kadoma, Kadoma City, Osaka Pref. Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] An inverter including a switching element for converting a commercial power supply to a high-frequency current; an on-time setting means for setting an on-time of the switching element; an input detection means for detecting an input to the inverter; First and second temperature detecting means for detecting a temperature, temperature control means for controlling an input to the inverter in accordance with a load temperature detected by the first temperature detecting means, and a second temperature detecting means Means for stopping the output signal of the on-time setting means when the temperature detected by the means is equal to or higher than a predetermined temperature at which input to the inverter is stopped by the temperature control means, or converting the output signal into a minimum on-time. And an on-time set by the on-time control means that the first temperature detection means or the temperature control means has failed and the excessive temperature rise prevention means has operated. An induction heating cooker having a temperature abnormality detecting means for performing an abnormality display by making a judgment according to the interval and an input detected by the input detecting means. 2. The on-time control, comprising: load detection means for performing heating at a predetermined cycle for a predetermined time to check for the presence or absence of a load when a load temperature is high and input to the inverter is stopped. If the abnormal state determined according to the on-time set by the means and the input detected by the input detection means continues continuously for the predetermined time or more, the first temperature detection means or the temperature control means fails. The induction heating cooker according to claim 1, wherein it is determined that the excessive temperature rise prevention means has operated.