JPS615319A - Temperature controller - Google Patents

Abstract

PURPOSE:To improve the reliability for safety of an electric blanket, etc., by securing such a system where the impedance of a temperature-sensitive element is reduced to cut off the energization to a heating element of the electric blanket, etc. when the temperature of the heating element rises extraordinarily and at the same time an abnormally high temperature of a control box is also sensed by a heat-sensitive element to cut off a heater circuit. CONSTITUTION:A heating element A is incorporated to an electric blanket main body M and connected to a wiring in a control box B via a connector P. When a switch SW is closed, a current flows via the SW, a heater H and a signal line S in a positive half cycle and a negative cycle of an SCR. In case the main body M has a low temperature, the voltage of a thermistor Th rises up owing to a high impedance and a capacity component. Thus a constant voltage conduction element D conducts. Then the SCR conducts for positive half cycle to energize the heater H. Thus the impedance of the thermistor Th is reduced. This reduces the conduction angle of the SCR to secure a steady state. The SCR is turned into a diode by some reason and the temperature rises abnormally to reduce the impedance of the Th. Thus the current of a resistance R1 increases to dissolve a fuse F2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature control device for electric blankets and the like.

Conventionally, in this type of device, a thyristor connected to the heating element is triggered in accordance with the impedance of the gate circuit to control the energization of the heating element and, in turn, to control the temperature.

However, with this type of device, for example, if the thyristor becomes a diode due to a failure in the thyristor's gate circuit, or if the thyristor fails and becomes conductive,
There is a risk that abnormal energization may cause the temperature to rise, leading to an accident such as a fire, so safety measures must be taken.

In view of this point, the present invention aims to improve reliability regarding safety, and embodiments will be described below with reference to the drawings.

The interior of the electric blanket body M is equipped with a heating element A, which is connected to the wiring in the control box B via the AI/i connector P, forming a circuit that will be explained in detail next. is a known one having the structure and characteristics shown in Fig. 4, in which the nylon thermistor Th interposed between the heater H and the signal line S decreases its impedance as the temperature rises, and leakage current flows accordingly. .

The AC power source EK includes a fuse F1, a thermal element such as a temperature fuse F2, and a thyristor such as an SCR.

Choke coil CH, above heater H and switch SW
are connected in series.

A resistor R3 is inserted between the gate electrode and the cathode of this SCR, and the gate circuit includes a constant voltage conduction element D1, a diode D3,
The signal line S, the resistor R2, and the variable resistor VR are sequentially connected in series and connected to the anode of S'CR.

A series circuit consisting of a diode D1 and a resistor R1 having a polarity opposite to the forward direction of the SCR is connected in parallel with the series circuit consisting of the resistor R2 and the variable resistor VR. This resistor R serves as a heat source for controlling the circuit release operation of the fuse F2.

That is, as shown in FIG. 3, a terminal plate T2 is closely attached to the outer peripheral surface of a solid resistor serving as a resistor R1, and a temperature fuse F2 is
An elastic terminal plate T is attached to this terminal plate T2 with low-temperature soldering as
1 are fixed in contact with each other, and when the amount of heat generated by the resistor R1 becomes sufficient, the fuse F2 melts and the terminal plate T2 separates from the terminal plate T2 due to its elasticity, opening the circuit. ing.

A diode D2- having a polarity opposite to the forward direction of the SCR is connected in parallel with the heater H.

Note that C is a capacitor for noise prevention, and the choke coil CH has a noise prevention effect.

The above configuration operates as follows.

When the switch SW is closed, l/iF, →p 2-+ in the forward half cycle (positive half cycle) of the SCR
vR, -+R2-+5-+T11-+)l-+5 W, and the thermistor Th shows a high impedance when the temperature of the blanket body M is low, and has a considerable capacitance component, so This capacitive component is charged. In this way, the voltage across the thermistor Th increases, and the voltage applied to the constant voltage conduction element also rises, and when this reaches the conduction voltage value of the element, a gate pulse is applied to the SCR to correct the voltage. Thyristor SCR in half cycle of
is made conductive to energize the heater H.

Then, depending on the operation of the variable resistor VR, the time point at which the constant voltage conduction element becomes conductive changes, and the amount of heat generated by the heater changes.

When the temperature of the heating element A rises due to the energization of the heater H, and the temperature of the electric blanket body M also rises, the impedance of the thermistor Th decreases, and S
The conduction angle of CR becomes small, and a steady state is reached at a temperature where the amount of heat generated by the heater H and the amount of heat dissipated from the electric blanket body M match.

This temperature can be varied by operating the variable resistor VR.

On the other hand, in the negative half cycle, by making the value of resistance R1 (22Ω) smaller than that of resistor R2 (approximately 300Ω), sw→H−+T
It can be approximated by the operation in which current flows as follows: h-+s-+D, →R1→F2→F, and will be explained using this.

If the temperature of heating element A is the normal operating temperature, thermistor T
Since the impedance of h is large and the current of resistor R1 is /J\, the amount of heat generated is insufficient, and the temperature fuse F2
will not melt.

If for some reason, for example, the SCR becomes a diode or a conductor, and the temperature rises further, and the impedance of the thermistor Th becomes a small value (approximately IKΩ or less), the current flowing through the resistor R1 will be large, and the amount of heat generated will also be large. Melt fuse F2 and open the circuit.

For example, if the above temperature fuse F2 is a low temperature solder of 95℃ and the resistor R is 22Ω, even under the condition that the power supply voltage has decreased to 80V, the thermistor "T"
We were able to obtain a circuit that opens within 2 minutes after the resistance value of h reaches 5000.

According to the present invention, as described above, if the temperature of the heating element rises abnormally, and for example, the temperature of an electric blanket rises abnormally, the impedance of the temperature sensing element decreases, enough leakage current is generated, and the leakage current is passed to the overheating element. It generates enough heat to immediately open the heat-sensitive element and cut off the electricity to the heating element, so even if the heating element reaches an abnormally high temperature, it only stays for a short period of time. This eliminates the disadvantage that temperature-sensitive elements such as nylon thermistors deteriorate due to carbonization due to high temperatures, and subsequent leakage current decreases, making it impossible to expect sufficient safe operation. Since the temperature sensing element is used both for temperature control and for cutting off current to the heating element by heating it when the temperature rises abnormally, the number of parts is small and the configuration can be extremely simplified. Temperature sensing during abnormal temperature rise throughout the heating element can be reliably performed.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram showing an embodiment of the temperature control device of the present invention, FIG. 2 is an electric circuit of the main part thereof, and FIG.
and (2) are a configuration diagram and an exploded perspective view of the circuit switch section, and FIGS. 4 (1) and (2) are a configuration diagram of the heating element and a characteristic curve diagram of the thermistor. Agent Patent attorney Aihiko Fukushi (and 2 others) (1)
No. 33 Procedural amendment 1 / Indication of the case Patent application 130056/1982 2. Name of the invention Temperature control device 3. Person making the amendment Relationship to the case Patent applicant 7. Contents of the amendment fl) Of the patent claim in the description We will correct the range column as shown in the attached sheet. (2) Page 7, line 3 of the specification states: [Temperature sensing can be performed reliably, and even if the temperature rises abnormally in the control box, the circuit can be successfully sensed and the circuit can be cut off. Control parts are also protected, and each temperature control part is built into the control box, so inspections and repairs can be carried out centrally in the control box. Repairs can also be carried out extremely easily and reliably. ”
I will correct it. Above 4, claims include a heating element connected to a power supply, a switching circuit inserted between the heating element and the power supply, and a signal line detecting the heat generation temperature of the heating element via a heat-sensitive resistor. a temperature detection circuit that controls opening and closing of the switching circuit; an element that overheats due to a change in the characteristics of the heat-sensitive resistor when the temperature of the heating element abnormally increases; and a heating element that is heated by the element and opens the heating circuit of the heating element. A heat-sensitive element inserted in series in the circuit and a temperature control device as described above. Procedural amendment April zz, 1985 2 Title of the invention Temperature control device 3 Relationship to the case of the person making the amendment Patent application Human body Location 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, 545
No. 6, Specification to be amended Particulars 1, Name of the invention Temperature control device 4, Brief description of the drawings Figure 1 is an electrical circuit diagram showing an embodiment of the temperature control device of the present invention. Figure 2 is an electrical circuit diagram of the main part, Figure 3 (1
) and (2) are a configuration diagram and an exploded perspective view of the circuit switch section, and FIGS. 4 (1) and (2) are a configuration diagram of the heating element and a characteristic curve diagram of the thermistor. 3. Detailed Description of the Invention The present invention relates to a temperature control device for electric blankets and the like. Conventionally, in this type of device, the cyrisk connected to the heating element was triggered in accordance with the impedance of the gate circuit to control the current flow to the heating element, which in turn controlled the temperature. However, with this type of device, if the wire is passed through, for example, there is a risk that it will be abnormally energized and the temperature will rise, leading to an accident such as a fire, so it is necessary to provide safety measures. In view of this point, the present invention aims to improve reliability regarding safety, and embodiments will be described below with reference to the drawings. A heating element A is housed inside the electric blanket main body M, and the heating element A is connected to the wiring in the control box B via a diaphragm P to form a circuit that will be described in detail below. This heating element A is a publicly known one having the structure and characteristics shown in FIG. , leakage current flows accordingly. The alternating current power source E includes and is connected in series with a fuse F3, a thermal element such as a temperature fuse F2, a heat sensitive element such as an SCR, a choke coil CH, the heater H, and a switch S. A resistor R3 is inserted between the gate electrode and the cathode of escH, and the gate circuit includes a constant voltage conduction element D and a diode 9.
The signal line S includes the tsubo resistance R2 and the variable resistor VR in series and is connected to the anode of the SCH. A series circuit consisting of a diode D and a resistor R1 having a polarity opposite to the forward direction of the SCH is connected in parallel with the series circuit consisting of the resistor R2 and the variable resistor VR. This resistor R serves as a heat source for controlling the circuit release operation of the fuse F2. That is, as shown in FIG. 3, a terminal plate T2 is closely attached to the outer peripheral surface of a solid resistor serving as a resistor R1, and an elastic terminal plate T1 is fixed in contact with this terminal plate T using low-temperature solder serving as a temperature fuse F2. I started to do this,
When the amount of heat generated by the resistor R1 becomes sufficient, the fuse F is melted and the terminal plate T1 is separated from the terminal plate T2 due to its elasticity, thereby opening the circuit. Kucoil CH has a noise prevention effect. The above configuration operates as follows. When the switch SW is closed, in the forward half cycle (positive half cycle) of the SCR, Fl → F2 → vR
-+R2→S-+Th-+H-+8w, and the thermistor Th shows a high impedance when the temperature of the blanket body M is low, and has a considerable capacitance component, so
This capacitive component is charged. In this way, the voltage across the thermistor Th increases, and the voltage applied to the constant voltage conduction element also rises, and when this reaches the conduction voltage value of the element, a gate pulse is applied to the SCR to correct the voltage. In the half cycle, the thyristor SCR is made conductive and the heater H is energized. Then, as the voltage becomes constant according to the operation of the variable resistor VR, and the temperature of the electric blanket body M also rises, the impedance of the thermistor Th decreases, and along with this, the SC
The conduction angle of R becomes small, and a steady state is reached at a temperature where the amount of heat generated by the heater H and the amount of heat dissipated from the electric blanket body M match. This temperature can be varied by operating the variable resistor VR. On the other hand, in the negative half cycle, the resistance R1 (22Ω)
By making the value of resistor R2 smaller than the value of resistor R2 (approximately 300Ω), SW-+H-+
Th-+S-+D1 →R1→F2→F. It can be approximated by the operation of passing current, and will be explained using this. If the temperature of heating element A is the normal operating temperature, thermistor T
Since the impedance of h is large and the current of resistor R1 is small, the amount of heat generated is insufficient, and the temperature fuse F2
will not melt. If for some reason, for example, the SCR generates a large amount of heat and melts the fuse F2, opening the circuit. For example, the above temperature fuse F2: 95°C low temperature solder,
When resistor R and +22 are set to Ω, the circuit opens within 2 minutes after the resistance value of thermistor Th reaches 500Ω at room temperature of 0°C, even under the condition that the power supply voltage drops to 80V. I was able to do that. According to the present invention, as described above, if the temperature of the heating element rises abnormally, and for example, the temperature of an electric blanket rises abnormally, the impedance of the temperature sensing element decreases, enough leakage current is generated, and the leakage current is passed to the overheating element. It generates enough heat to immediately open the heat-sensitive element and cut off the electricity to the heating element, so even if the heating element reaches an abnormally high temperature, it only takes a short time, and unlike conventional methods, the heating element remains abnormally high for a long time. When the temperature rises to high temperatures, the temperature sensing element, such as a nylon thermistor, deteriorates by carbonization, and subsequent leakage current decreases to ensure safe operation.Heating the heat sensing element at the desired temperature cuts off the current to the heating element. Since the element that senses the temperature of Moreover, even if the temperature of the control box rises abnormally, the heat-sensitive element built into the control box will be able to handle the problem (
It detects and cuts off the heater circuit, protecting each temperature control component built into the control box, and also allows inspection and repair of each temperature control component to be performed centrally at the control box. Repairs can also be carried out very easily and reliably. 4. Scope of Claims A heater for a heating element connected to a power source, an element that is inserted between the heater for this heating element and the power source and that overheats due to switching, and a heating element that is heated by this element and heated by the heating element. 1. A temperature control device comprising: a heat-sensitive element inserted in series in the heater circuit to open the heater circuit; and a control box incorporating the above-mentioned control components.

Claims (1)

[Claims] A heating element connected to a power supply, a switching circuit inserted between this heating element and the power supply, and a temperature at which the temperature of the heat generated by the heating element is detected by a signal line via a heat-sensitive resistor to control opening and closing of the switching circuit. a detection circuit; an element that heats due to a change in the characteristics of the heat-sensitive resistor when the heating element abnormally rises in temperature;
A temperature control device comprising: a heat-sensitive element inserted in series in the heating circuit that opens the heating circuit of the heating element when heated by the element.