JPS6333350Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a temperature control device for electric blankets, electric carpets, etc., and particularly relates to a temperature control device with improved safety.

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

As shown in FIG. 1, the temperature control device of the present invention has a power supply 1, a switch 2, a current fuse 3, a heating wire 5 forming a heating element 4, a thyristor 6, and a temperature fuse 7 connected in series to form a main circuit. A diode 8 is connected between the connection point of the current fuse 3 and the heat generating wire 5 and the cathode of the thyristor 6, and a heat generating wire is wound around the heat generating wire 5 via a thermistor (for example, nylon #11) 9 which melts at high temperature. Shorting wire 10, resistor 11, diode 12, resistor 1 forming body 4
A series circuit of a diode 16 and a resistor 17 for heating the temperature fuse 7 is connected, and a series circuit of a resistor 18 and a capacitor 19 is connected between the anode and cathode of the thyristor 6. When the circuit is connected, the gate of the thyristor 6 is connected to the resistor 14 and the resistor 1.
A diode 20 is connected to the connection point of the current fuse 3 and the heating wire 5 in parallel to the heating wire 5, and a signal line 23 of the heat sensitive body 22 that senses the heat generated by the heating wire 5 is connected to the connection point of the current fuse 3 and the heating wire 5. A signal line 25 forming a heat sensitive body 22 is connected to the signal line 23 and wound through a thermistor (for example, vinyl chloride) whose impedance changes depending on the temperature. A transistor 3 is connected to the cathode of the thyristor 6 through a series circuit of a diode 29 and a capacitor 30 at the connection point between the resistor 26 and the resistor 27.
The base of the transistor 31 is connected to the base of the transistor 31, the collector of the transistor 31 is connected to the connection point of the resistor 13 and the resistor 14, and the emitter is connected to the cathode of the thyristor 6, and a resistor is connected between the emitter and the base of the transistor 31. 33 and diode 2
2 series circuits are connected, and the emitter of the transistor 31, the diode 29, and the capacitor 30 are connected.
A resistor 35 is connected to the connection point of the transistor 31, and an indicator lamp 36 and the resistor 3 are connected to the connection point of the emitter of the transistor 31, the current fuse 3, and the heating wire 5.
It is constructed by connecting seven series circuits.

Incidentally, the heating element 4 used in the above configuration has a heating wire 5 wound around a core wire 38 as shown in FIG.
It is constructed by winding a shorting wire 10 around the heating wire 5 via a thermistor 9 which melts at high temperature and covering it with an insulator 39, and the heat sensitive body 22 is formed by a core wire 40 as shown in FIG. A signal line 23 is wound around the signal line 23, and a signal line 25 is wound around the signal line 23 via a thermistor 24 whose impedance changes depending on the temperature, and the signal line 25 is covered with an insulator 41.

Next, the operating state of the temperature control device of the present invention constructed as described above will be explained.

Now, when the switch 2 is turned on, the power supply 1 connects the switch 2, the current fuse 3, the diode 8, the shorting wire 10 of the heating element 4, the resistor 11, and the diode 1.
2. The gate circuit of the thyristor 6 is energized by the resistors 13, 14, 15 and the temperature fuse 7, and a DC voltage is applied to the gate of the thyristor 6, turning the thyristor 6 on, and the heating wire of the heating element 4 is turned on. 5. The circuit of the thyristor 6 energizes the heating wire 5 of the heating element 4, so that the heating wire 5 of the heating element 4 is in a heating state. In this case, at the initial stage of energization, the temperature sensed by the heat sensitive body 22 is low, so the impedance of the thermistor 24 interposed between the signal line 23 and the signal line 25 of the heat sensitive body 22 is high, and the impedance of the thermistor 24 is high, and the resistor 27 and variable resistor The voltage divided by the series circuit of 28 is low, and the charge charged in the capacitor 30 due to the voltage across the terminal does not turn on the transistor 31, and the transistor 31 is in the off state. Therefore, the gate of the thyristor 6 is The above gate voltage continues to be applied, and the thyristor 6 continues to be turned on. At this time, the thyristor 6 is turned on from zero volts in each cycle in the positive direction (in the conduction direction of the thyristor 6), and is completely turned on during the half cycle.

When the temperature rises to the set value due to heat generated by the heat generating wire 5 of the heat generating element 4, the signal line 23 of the heat sensitive element 22
The impedance of the thermistor 24 of the signal line 25 becomes low, and the voltage divided by the series circuit of the resistor 27 and the variable resistor 28 becomes high, and during the negative cycle of the voltage across the thyristor 6, this voltage is applied to the variable resistor. 28, resistor 33, diode 3
2, capacitor 30, diode 29, resistor 27
The capacitor 30 is charged by the circuit, and during the next positive cycle, the charge of the capacitor 30 is discharged by the base-emitter of the transistor 31 and the circuit of the resistor 35, and the transistor 31 is turned on and the collector of the transistor 31 is charged. - The emitters are short-circuited, and therefore the gate circuit of the thyristor 6 is short-circuited by the transistor 31, the thyristor 6 is turned off, and the heating wire 5 of the heating element 4 stops generating heat. In this case, the transistor 31
is turned on and off by discharging the capacitor 30, and as described above, the capacitor 30 charges the thyristor 6 in the negative cycle and discharges in the next positive cycle. The values of the resistors 33 and 35 are selected so that the discharge continues, and the values of the resistors 13 and 35 are selected so that the thyristor 6 is turned off when the transistor 31 is turned on.
A value of 14 is selected so that the transistor 31 is turned on at a time slightly earlier than the time when the thyristor 6 reaches the gate voltage that turns it on.

In this way, when the thyristor 6 is turned off and the temperature of the heating wire 5 of the heating element 4 decreases, and the impedance of the thermistor 24 of the heat sensitive element 22 increases, the voltage across the resistor 27 and the variable resistor 28 decreases again.
Therefore, the charging voltage of capacitor 30 becomes low and transistor 31 is turned off. The timing at this time is when the peak value of the negative cycle for the thyristor 6 becomes less than the off-state voltage of the transistor 31, so the next positive cycle will always be off from the beginning, and the thyristor 6 will be turned off during the positive cycle. is completely turned on.

The temperature is controlled to a predetermined set temperature state by repeating the above operations.

The variable resistor 28 is used to arbitrarily select the set temperature, and by increasing the value of the variable resistor 28, the temperature can be set to a low temperature, and by decreasing the value, the temperature can be set to a high temperature. can.

Next, to explain the operation of the safety device, in the case where the transistor 31 fails or the thyristor 6 becomes a diode and loses its control function, the temperature of the heating wire 5 of the heating element 4 continues to rise. The thermistor 9 on top of the heating wire 5 melts (in the case of nylon #11, it melts at around 190°C), and the heating wire 5 and the shorting wire 10 are short-circuited, and the power supply 1, temperature fuse 7, resistor 17, diode 16 are shorted. In the circuit of the wire 10, thermistor 9, heating wire 5, and current fuse 3, current flows through the resistor 17, which generates heat, and the temperature fuse 7 near the resistor 17 causes the resistor 1 to generate heat.
7, the temperature fuse 7 is blown and the circuit is cut off. This operation operates as a safety device not only when the thyristor 6 fails, but also against local heating of the heating element 4 or danger from external heating.

In addition, the gate circuit of the thyristor 6 consisting of the diodes 8, 12 and the resistors 11, 13, 14 via the short-circuit wire 10 of the heating element 4 maintains the reliability of the above-mentioned safety device, and in the unlikely event that the short-circuit wire 10 is disconnected. In this case, or in the event of an abnormality such as poor contact between the control device and the blanket section, the gate circuit of the thyristor 6 will stop operating, and the heating wire 5 will not generate heat, ensuring safety. In other words, the gate circuit of the thyristor 6 is operating normally, indicating that the safety device is also connected more reliably. and diode 20
In the event that the thyristor 6 is short-circuited, a large current is instantaneously passed through the diode 20 to blow the current fuse 3.

In the above configuration, the resistor 18 and capacitor 19 are used to protect the thyristor 6, and the resistor 3
7 is for protecting a neon lamp 36 that displays circuit operation. A transistor may be used instead of the thyristor 6, and the thyristor 6 may be a switching element that is controlled by a control current.

Since the present invention has the above-mentioned configuration, if the switching element fails and an overcurrent flows through the heating wire of the heating element and overheats, the circuit can be cut off and safety can always be maintained, and the short circuit wire can be disconnected. If an abnormality occurs such as poor contact between the control device and the blanket part, the circuit will not operate, ensuring safety. It has advantages such as being able to shorten the time from when the temperature is heated to when it reaches a predetermined temperature.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the temperature control device of the present invention, Fig. 2 is a cross-sectional perspective view of the main part of the heat generating element shown in Fig. 1, and Fig. 3 is a main part of the heat sensitive element shown in Fig. 1. It is a cross-sectional perspective view. In the figure, 1 is a power supply, 5 is a heating wire, 6 is a thyristor, 7 is a temperature fuse, 9 is a thermistor, and 10 is a shorting wire.

Claims (1)

[Scope of utility model registration request] A signal current for controlling the switching element is passed through a main circuit in which a heating wire, a switching element, and a temperature fuse are connected in series to the power supply, and a short-circuit wire wound around the outside of the heating wire via a thermistor that melts at a relatively high temperature. A control circuit that is controlled by a signal from a signal line arranged independently of the heating wire is provided, and a device for blowing out the temperature fuse with a current having a reverse relationship to the control signal current of the control circuit is connected to the short-circuit wire. A temperature control device characterized in that it is connected in parallel with a circuit that obtains a signal current for controlling a control circuit.