JPH113123A - Electric heating appliance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric heating appliance, with which the disconnection of thermistor can be detected in extremely simple configuration, concerning the electric heating appliance having the thermistor. SOLUTION: This appliance is provided with a temperature detection part A having the thermistor, temperature storage part C for storing temperature setting and disconnection detection part B parallelly connecting another temperature setting part D to the temperature storage part C so as to cancel the temperature stored in the temperature storage part C when this thermistor is detected. Thus, when the disconnection detection circuit B is operated, this appliance works outside a temperature control range, and electrification of a temperature controller is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric heating apparatus having a thermistor, which is provided with a safety control circuit for easily detecting disconnection of the thermistor and disconnection of the wiring path of the thermistor and stopping the supply of electricity to the temperature control device. It is about.

[0002]

2. Description of the Related Art Conventionally, disconnection detection of a thermistor is performed, for example, as shown in FIG.
Temperature detector A in which a resistor 52 and a thermistor 53 are connected in series
A and a temperature setting unit BB including a variable resistor 56 are provided.
The voltage divided by the resistor 61 and the resistor 62 is used as a non-inverting input,
The comparator 63 has an inverting input of the output voltage VTH of the temperature detecting section AA, and a disconnection detecting circuit DD having a configuration in which a cathode side of a rectifier 64 is connected to an output terminal of the comparator 63, and an output voltage of the temperature detecting section AA. The VTH, the output voltage VAJ of the temperature setting unit BB, and the output voltage VDD of the disconnection detection circuit DD are input as inverting inputs via resistors 54, 55, 65, respectively.
And an operational amplifier 60 having a non-inverting input of a deviation reference voltage VBB divided by a resistor 58 and an inverting input terminal and an output terminal of the operational amplifier 60 are connected to each other. The operation of the disconnection detection circuit DD at the time of disconnection
It is described that the output terminal voltage of 0 rises, and the temperature control device can operate to lower the temperature by increasing the detection temperature of the temperature detection unit AA to TAA ′ with respect to the set temperature TAA as shown in FIG. ing.

[0003]

However, in the above-described conventional configuration, when the disconnection detecting circuit operates, it is considered that the circuit operates within the temperature control range, and the minimum heating is continued.
This means that the power supply to the temperature control device is being continued, and it is difficult for the user to recognize that there is an abnormality (disconnection of the thermistor). There was a problem that it was necessary.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide an electric heating apparatus which can detect disconnection of a thermistor with a very simple configuration.

[0005]

In order to solve this problem, an electric heating apparatus according to the present invention comprises a temperature detecting section having a thermistor, a temperature storing section for storing a temperature setting, and a temperature storage section for storing a temperature. A setting unit is connected in parallel, and is provided with a disconnection detecting circuit for releasing the temperature stored in the temperature storage unit when the thermistor is disconnected.

According to the present invention, when the disconnection detecting circuit operates, the power supply to the temperature control device is stopped, and wasteful power consumption is eliminated. By stopping the energization, the user can easily recognize that an abnormality has occurred (a disconnection of the thermistor). In the case of a plurality of thermistors, a good electric heating appliance can be obtained with one disconnection detection circuit.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention detects a temperature of a load, and detects a temperature of at least a thermistor; a temperature storage unit comprising a capacitor for storing a temperature setting; A temperature setting unit is connected in parallel to the capacitor of the storage unit, and a disconnection detection circuit that releases the temperature stored in the temperature storage unit when the thermistor is disconnected.If the disconnection detection circuit operates, This has the effect that the power supply to the temperature control device can be stopped.

According to a second aspect of the present invention, in the first aspect of the present invention, the disconnection detecting circuit is constituted by one comparator for a temperature detecting section having a plurality of thermistors. Thus, even if any one or a plurality of thermistors is disconnected, it can be detected.

An embodiment of the present invention will be described below with reference to FIGS. (Embodiment 1) FIG. 1 is a circuit diagram showing a configuration of an electric heating apparatus according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a power supply, and a temperature detecting section A includes a thermistor 2 and a resistor. 3 are connected in series. Further, the disconnection detection circuit B has a comparator 8 in which the voltage divided by the resistor 6 and the resistor 7 is an inverting input, and the output voltage VA of the temperature detecting unit A is a non-inverting input voltage. It is configured to be connected to the capacitor 17 of the temperature storage unit C via the resistor 10. Further, the temperature storage unit C uses the voltage divided by the resistor 11 and the resistor 12 as a non-inverting input, and
And a resistor 14 connected to the power supply 1 side at the output terminal of the comparator 13 and connected to the anode side of the rectifier 15 to output the rectifier 1.
5 is connected to a midpoint where a start switch 16 which is a non-locking push button switch connected to the power supply 1 and a capacitor 17 are connected in series, and the cathode side of the rectifier 15 is used as an input of the temperature control device 31. It is configured as follows. Further, the temperature setting unit D has a non-inverting input of a voltage divided by the resistor 18 and the resistor 19, and a comparator 20 having an output voltage VA of the temperature detecting unit A as an inverting input voltage, and a resistor 21 at an output terminal of the comparator 20. The start switch 16 and the capacitor 17 of the temperature storage unit C are connected via the resistor 21 to the midpoint of the series connection. The temperature controller 31 is energized by the output of the temperature storage unit C.

FIG. 2 shows an output characteristic diagram for the temperature control device. In FIG. 2, when the practical temperature range of the thermistor 2 and the resistor 3 of the temperature detecting unit A by the voltage dividing circuit is TA to TA ′, the temperature TC stored by the voltage dividing circuit of the resistors 11 and 12 of the temperature storage unit C and the temperature The set temperature TD by the voltage dividing circuit of the resistors 18 and 19 of the setting unit D is from the practical temperature range TA to TA '.
, And the disconnection detection temperature TB by the voltage dividing circuit of the resistors 6 and 7 of the disconnection detection circuit B is on the low temperature side outside the practical temperature range TA to TA ′.

[0011] As an electric heating device configured as described above,
The operation of the electric pot will be described below. The load 32 is water. The practical temperature range TA to TA ′ is 100 ° C. from 0 ° C. to boiling. Here, the storage temperature TC is set to 80 ° C. The disconnection detection temperature TB is, for example, −20 ° C. outside the practical temperature range TA to TA ′.

First, when a start switch 16 which is a push button switch which is not locked is turned on, a capacitor 17 is turned on.
Is charged to the power supply voltage 1 and becomes a voltage (“H”) larger than the threshold value to the input of the temperature control device 31, and starts energization, and the water temperature rises. The capacitor 17 continues charging through the resistor 14 and the rectifier 15 connected to the power supply until the hot water temperature reaches the storage temperature TC, and the hot water temperature continues to rise. When the hot water temperature of the load 32 exceeds the storage temperature TC of 80 ° C., the voltage on the inverting input side of the comparator 13 becomes higher than the voltage on the non-inverting input side, and the charging of the capacitor 17 is turned off. Although the charging of the capacitor 17 is turned off, the power supply to the temperature control device 31 is continued because the voltage of the capacitor 17 is higher than the threshold voltage of the temperature control device 31.

Further, when the hot water temperature exceeds the storage temperature TD of 95 ° C., the voltage on the inverting input side of the comparator 20 becomes higher than the voltage on the non-inverting input side, and the output of the comparator 20 changes from “H” to “L”. That is, the voltage of the capacitor 17 is discharged via the resistor 21. When the voltage of the capacitor 17 becomes lower than the threshold voltage of the temperature control device 31, the power supply to the temperature control device 31 is stopped.

In any operating state of the electric pot,
When the thermistor 2 is disconnected, the voltage on the inverting input side of the comparator 8 becomes higher than the voltage on the non-inverting input side, the output of the comparator 8 changes from "H" to "L", and the voltage of the capacitor 17 is passed through the resistor 10. Immediately, the power supply to the temperature control device 31 is stopped. Start switch 1 when thermistor 2 is disconnected
Even if 6 is turned on, the capacitor 17 is not charged and the temperature control device 31 is not energized.

Therefore, when the thermistor 2 is disconnected, since the disconnection is detected outside the practical temperature range TA to TA ', the power supply to the temperature control device 31 is completely stopped, so that a safe electric heating appliance can be provided.

(Embodiment 2) FIG. 3 is a circuit diagram showing a configuration of an electric heating apparatus according to a second embodiment of the present invention, showing a case where there are a plurality of thermistors. Note that the same components as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

In the figure, a water temperature is detected by a temperature detecting section A in which a thermistor 2 and a resistor 3 are connected in series, and steam at the time of boiling is detected by a temperature detecting section E in which a thermistor 4 and a resistor 5 are connected in series. By detecting steam exclusively with the thermistor 4,
It has the advantage that it can be boiled reliably even in high altitude areas with low atmospheric pressure. The voltage divided by the resistor 6 and the resistor 7 is used as an inverting input, and the output voltage VA of the temperature detecting unit A is changed to a rectifier 22.
, And the anode of the rectifier 22 is used as a non-inverting input. A disconnection detection circuit B having a configuration in which the output voltage VE of the temperature detection unit E is connected to the cathode of the rectifier 23 and the anode of the rectifier 23 has a non-inverting input, and a resistor 10 is connected to the output terminal of the comparator 8. When one or more of the thermistors is disconnected, for example, when the thermistor 2 is disconnected, the voltage on the inverting input side of the comparator 8 becomes higher than the voltage on the non-inverting input side, and the output of the comparator 8 Changes from "H" to "L", the charged voltage of the capacitor 17 is immediately discharged via the resistor 10, and the power supply to the temperature control device 31 is stopped. Even if the start switch 16 is turned on again, the capacitor 17 is not charged and the temperature control device 31
No power is supplied to the

Therefore, even if any of the plurality of thermistors is disconnected, the disconnection is detected outside the practical temperature range TA to TA 'and the power supply to the temperature control device 31 is completely stopped, so that a safe electric heating appliance can be provided. In addition, the disconnection detection circuit can be configured with one comparator for the temperature detection unit having a plurality of thermistors, and can be inexpensive.

[0019]

As described above, according to the present invention, a temperature detecting section, a temperature storing section for storing a temperature setting, and another temperature setting section are connected in parallel to the temperature storing section so that the temperature of the thermistor can be reduced. By providing a disconnection detection circuit for canceling the storage of the temperature storage unit, when the disconnection detection circuit operates, it operates outside the temperature control range, and the power supply to the temperature control device is stopped.

The same effect can be obtained even if the disconnection detecting circuit is constituted by one comparator for the temperature detecting section having a plurality of thermistors. Furthermore, even if the thermistors having the same characteristics (positive characteristics and negative characteristics) or thermistors having different characteristics can be detected reliably, the breakage of the thermistors can be detected, and the effect of providing a safe electric heating appliance can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of an electric heating appliance according to a first embodiment of the present invention.

FIG. 2 is an output characteristic diagram for a temperature control device according to the embodiment.

FIG. 3 is a circuit diagram showing a configuration of an electric heating device according to a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a configuration of a conventional electric heating appliance.

FIG. 5 is an output characteristic diagram to a temperature control device in the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC power supply 2, 4 Thermistor 8, 13, 20 Comparator 15, 22, 23 Rectifier 16 Start switch 17 Capacitor 31 Temperature controller 32 Load A, E Temperature detection part B Disconnection detection circuit C Temperature storage part D Temperature setting part

Claims (2)

[Claims] 1. A temperature detecting unit having at least a thermistor for detecting a temperature of a load, a temperature storing unit comprising a capacitor and storing a temperature setting, and a temperature setting unit connected in parallel to the capacitor of the temperature storing unit. And a disconnection detecting circuit for canceling the storage of the temperature storage unit when the thermistor is disconnected. 2. A disconnection detection circuit comprising a single comparator for a temperature detection section having a plurality of thermistors.
An electric heating appliance as described.