JPS6347018Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial field of application The invention relates to temperature control of a yagura kotatsu, and is designed to achieve a steep temperature rise even when the temperature is set at a medium-low temperature. .

3. Configuration of conventional example and its problems FIG. 3 shows a circuit diagram for temperature control of a conventionally used electric kotatsu, and the following control is performed. That is, a bidirectional thyristor 4 is connected in series to the heater 2 to adjust the temperature by phase control. series circuit and capacitor 7,1
2, a current limiting resistor 8, a temperature fuse 1 to prevent the internal temperature of the kotatsu from rising too high, a noise prevention capacitor 3, and a chiyoke coil 6.

The temperature inside the kotatsu is determined by adjusting the variable resistor 11, and is determined by the sum of the resistance values of the positive temperature coefficient thermistor 9 and the variable resistor 11. Capacitor 7, 12
When the charging voltage reaches the breakover voltage of the ignition element 5, the bidirectional thyristor 4 becomes conductive.
The heater 2 is energized.

Therefore, when the resistance value of the variable resistor 11 is reduced, the charging speed of the capacitors 7 and 12 becomes faster, the conduction angle of the bidirectional thyristor 4 becomes larger, and the amount of current flowing through the heater 2 increases, so that the temperature inside the kotatsu becomes high. Become.

When the temperature inside the kotatsu rises, the resistance value of the positive temperature coefficient thermistor 9 that detects the internal temperature increases, so the charging speed of the capacitors 7 and 12 decreases, the conduction angle of the bidirectional thyristor 4 also decreases, and the heater 2
The amount of electricity applied to the kotatsu is also reduced, and the temperature rise inside the kotatsu is also limited.

Now, the resistance value of the positive temperature coefficient thermistor 9 is sufficiently low at the initial stage of energization when the variable resistor 11 is at its maximum, that is, when the temperature inside the kotatsu is lowered, so the capacitors 7 and 12
Since the charging current becomes the resistance value of the variable resistor 11 and the conduction angle of the bidirectional thyristor 4 is limited from the beginning, it takes a long time to reach the set temperature.

FIG. 4 shows the rise characteristics when the variable resistor 11 is changed in three stages.

d is a temperature rise graph inside the kotatsu when the variable resistor 11 is set to the minimum value, e is the variable resistor 11 set to the middle position, and f is the temperature rise graph when the variable resistor 11 is set to the maximum value.

As can be seen from FIG. 4, unless the temperature inside the kotatsu is set high, e and f have poor rise temperature characteristics and have the problem of requiring a long time to reach the appropriate temperature.

Purpose of the invention The present invention eliminates these conventional problems, and makes the rise temperature characteristics almost constant regardless of the set temperature.

Structure of the invention The invention connects a series circuit of a positive temperature coefficient thermistor 9 and a variable impedance element for detecting the temperature inside the kotatsu in parallel to a bidirectional thyristor.
The current generated by the voltage generated across the variable impedance element is supplied as the trigger current of the bidirectional thyristor.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, the same parts as in FIG. 3 are given the same numbers, 10 is a resistor, 11 is a variable resistor, and 13 is a variable impedance element.

Considering the initial stage of energization when the temperature inside the kotatsu is low, the positive temperature coefficient thermistor 9 has a low resistance. The resistor 10 is a current limiting resistor and has a resistance value less than 1/20 of the resistance value of the positive temperature coefficient thermistor 9 during operation, so it does not affect the operation. When the variable resistor 11 is set to a low temperature, that is, when it is set to a low impedance, it has a higher impedance than the positive temperature coefficient thermistor 9, so the voltage across the variable impedance element 13 increases and the conduction angle of the bidirectional thyristor 4 increases. is large, the amount of current applied to the heater 2 also becomes large, and the temperature inside the kotatsu rises rapidly as shown in FIG. 2c.

When the variable resistor 11 is set to a medium temperature, the variable resistor 11 has a medium resistance value, so the voltage across the impedance element 13 is high, the conduction angle of the bidirectional thyristor 4 becomes large, and the amount of current flowing through the heater 2 increases. The temperature inside the kotatsu also increases rapidly, as shown in Figure 2b.

When the variable resistor 11 is set to a high temperature, the variable resistor 11 has a high resistance value, so the voltage across the impedance element 13 increases, the conduction angle of the bidirectional thyristor 4 also increases, and the amount of current flowing through the heater 2 increases. The temperature inside the kotatsu also increases rapidly, as shown in Figure 2a.

When the variable resistor 11 is set to a high temperature, the variable resistor 11 has a high resistance value, so the voltage across the impedance element 13 increases, the conduction angle of the bidirectional thyristor 4 also increases, and the amount of current flowing through the heater 2 increases. The temperature inside the kotatsu also increases rapidly, as shown in Figure 2a.

If we consider the case where the temperature inside the kotatsu rises, the positive characteristic thermistor 9 installed inside the kotatsu will have a high resistance, so the voltage across the variable impedance element 13 will be high depending on the setting of the variable resistor 11. Changes from voltage to lower voltage.

When this voltage becomes lower, the rate at which the capacitor 7 is charged through the resistor 8 becomes slower, so that the breakover time of the ignition element 5 becomes slower, and the conduction angle of the bidirectional thyristor becomes smaller. Then, the amount of heat generated by the heater 2 also decreases, so the temperature rise inside the kotatsu is limited and kept constant.

FIG. 5 shows another embodiment, which differs in that resistors 8 and 8' are connected to the sliding poles of the variable resistor 11 of the variable impedance element 13.

Similar effects can be obtained in this embodiment as well.
In this embodiment, if the resistor 8' is set lower than the operating resistance of the positive temperature coefficient thermistor 9, a voltage dividing circuit is formed by the positive coefficient thermistor 9 and the variable impedance element 13, and when the temperature setting is set to low. However, a large voltage is applied to the capacitor 7, the conduction angle of the bidirectional thyristor 4 is large, and the amount of current flowing through the heater 2 is also large, so that the temperature inside the kotatsu can be rapidly increased.

Effects of the invention As is clear from the above explanation, the invention consists of a series circuit consisting of a positive temperature coefficient thermistor that detects the temperature inside the kotatsu and a variable impedance element, and the current generated by the voltage across the variable impedance element is bidirectional. Since it is used as a trigger current for a thyristor, a rapid temperature rise can be expected even when the temperature setting is low.

Furthermore, when the set temperature is reached, the positive temperature coefficient thermistor becomes high in resistance and the temperature is controlled, so there is no danger of abnormal temperatures.

Therefore, it is possible to solve the conventional problem that the rise temperature characteristic becomes extremely slow depending on the temperature setting.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of an electric kotatsu according to the present invention. FIG. 2 is a rise temperature characteristic diagram of the electric kotatsu from the initial stage of energization until it reaches the set temperature. FIG. 3 is a conventional circuit diagram. FIG. 4 is a rise temperature characteristic diagram of the conventional electric kotatsu from the initial stage of energization until the set temperature is reached. FIG. 5 is a circuit diagram showing another embodiment of the present invention. 2... Heater, 4... Bidirectional thyristor, 9
...Positive characteristic thermistor, 13...Variable impedance element.

Claims (1)

[Scope of utility model registration request] A series circuit of a positive temperature coefficient thermistor for detecting temperature inside the kotatsu and a variable impedance element is connected in parallel to a bidirectional thyristor that controls the power supply to the heating element, and the current due to the voltage generated across the variable impedance element is bidirectionally connected. An electric kotatsu that supplies the trigger current to a thyristor.