JPH0113632B2 - - Google Patents

Description

Detailed Description of the Invention Technical Field The present invention includes a heater that is powered through a switching element, such as a thyristor, that switches between a conduction state and a blocking state in response to an ignition signal, and that Concerning electric heating cloth that increases temperature.

Prior Art In the above electric heating cloth, a heating wire is spirally wound around a core wire, the heating wire is coated with a material whose impedance changes depending on the temperature, such as nylon, and a conductive wire is further placed on top of the heating wire. Some devices are equipped with an electric heating element made by winding a detection wire. This electric heating cloth is heated by the above-mentioned heater wire that generates heat when energized.

When the heater wire generates heat, the impedance of the nylon covering it changes. When the change in impedance exceeds a preset tolerance value, the change is detected by a suitable detection means, and the power supply to the heater wire is cut off based on this. Thereby, the amount of heat generated by the heater wire, and therefore the temperature of the electric heating cloth, is maintained at a desired constant temperature.

However, since nylon has the property of absorbing water, when it is used in a humid electric heating cloth, the impedance of the nylon decreases due to water absorption. Therefore, the nylon must be thoroughly dried in order for its impedance to indicate the correct temperature of the heater wire. Because it takes a very long time, say 10 to 20 hours, for the nylon to dry sufficiently, the nylon is actually damp when using this heating cloth, so the temperature of the heating wire is accurate. This means that it has not been detected. Specifically, since the impedance of nylon appears lower than the actual impedance, the detected temperature of the heater wire will be higher than the actual impedance. This means that
This means that the power supply to the heater is cut off before the temperature of the heater wire rises to the desired temperature, resulting in the inconvenience that the temperature of the electric heating cloth does not rise to the desired temperature no matter how long it takes. arise.

Purpose In view of the above points, an object of the present invention is to provide an electric heating cloth that can maintain the temperature of the heater at a desired constant value by accurately detecting the temperature of the heater without being affected by humidity. do.

Another object of the present invention is to control the temperature of the heater using one detection wire, and at the same time, when an abnormal current flows through the heater wire, the detection wire is used to supply power to the heater wire. The purpose of the present invention is to provide an electric heating cloth that can be safely controlled to shut off.

composition The above object is achieved by the following electric heating cloth.

A material whose impedance changes depending on the temperature in an electric heating cloth that is equipped with a heater that is supplied with power through a switching element that switches between a conductive state and a blocked state in response to an ignition signal, and whose temperature rises due to the heat generated by the heater. A heater covering material formed by a heater covering material and covering the above-mentioned heater, a detection wire arranged outside the heater covering material and whose electrical resistance value changes depending on the temperature, and detecting changes in the electrical resistance value of the detection wire. a heater temperature control device that ignites the switching element, and a heater temperature control device that is disposed in the power supply path to the heater and shuts off power to the power supply path when the current flowing through the detection wire exceeds a permissible value. The present invention is an electrically heated cloth characterized by having a current cutoff element.

Hereinafter, the present invention will be explained using drawings showing embodiments thereof.

FIG. 1 is an overall view of the electric heating cloth according to the present invention.
Inside the electric heating cloth 1, an electric heating element 2 is arranged as shown by the broken line. Warm cloth 1. A temperature controller 5 is provided in the middle of the power supply line 4 .

As shown in FIG. 2, the electric heating element 2 has a heater wire 7 wound around a core material 6, and a heater wire 7 made of a material whose impedance changes depending on the temperature, for example, nylon 8, is wrapped around the core material 6. Cover the nylon 8 with a coating material, then wrap the detection wires 9 around the nylon 8, and finally wrap these detection wires with heat-resistant vinyl 1.
It is made by covering it with 0. The detection wire 9 is made of a conductive material whose electrical resistance value changes depending on temperature changes.
For example, it is made of materials including copper, nickel, etc.

FIG. 3 shows a circuit for controlling the current supplied to the heater wire 7, which is housed in the controller 5 in FIG. In Fig. 3, the AC 100 ^V supplied through the plug 11 is stepped down by the transformer TR with a phase shift of 180°.
It is rectified by a diode D3 and a resistor R7, and is applied to a series voltage divider circuit 12 consisting of a sensing line 9, variable resistors VR and R10. The series voltage dividing circuit 12 is one element constituting the heater temperature control device 13.

The heater temperature control device 13 includes a series voltage dividing circuit 12
A comparator 14 that receives the output voltage of the comparator 14 as an input signal at its terminal, a reference voltage circuit 16 that sends a reference voltage signal to the terminal of the comparator 14, and a switching element that is activated by the output signal from the comparator 14. thyristor SCR2.
The thyristor SCR2 is arranged on the power supply path of the heater wire 7 as shown in the figure.

The reference voltage circuit 16 connects the secondary voltage of the transformer TR to a diode D4, a resistor R8, and a capacitor C1.
and Zener diode RD3 to provide a constant DC voltage, and the constant voltage is controlled by variable resistor VRT and resistor R1.
2 and a resistor R13, the voltage is divided and output.

When the temperature of the heater wire 7 is low, that is, when power should be supplied to the heater wire 7, the resistance value of the detection wire 9 is small, and therefore the voltage V1 of the voltage dividing circuit 12 (hereinafter referred to as detection voltage) is a high value. The detection voltage V1 is the output voltage of the reference voltage circuit 16, that is, the comparator 14
When the reference voltage V2 is higher than the reference voltage V2, the comparator 14 outputs an ignition signal V3, which causes the thyristor SCR2 to ignite and current to flow through the heater wire 7. As a result, the heater wire 7 generates heat and the electric heating cloth 1 (FIG. 1) is warmed.

As the temperature of the heater wire 7 rises, the resistance value of the detection wire 9 gradually increases, and accordingly the detection voltage V
1 becomes lower. When the detection voltage V1, which gradually decreases in this way, becomes lower than the reference voltage V2, the comparator 1
Since the ignition signal V3 from the heater wire 4 disappears, the thyristor SCR2 remains in the OFF state, and no power is supplied to the heater wire 7. Therefore, the heater wire 7 stops generating heat, and the temperature of the heater wire itself and the temperature of the electric heating cloth 1 (FIG. 1) gradually decrease. At this time, the resistance value of the detection line 9 becomes small, and therefore the detection voltage V
1 becomes higher. When the detection voltage V1 exceeds the reference voltage V2, the thyristor SCR2 is fired again and the heater wire 7 generates heat. That is, the heater 7 repeatedly generates and extinguishes heat so that the detected voltage V1 becomes equal to the reference voltage V2, and thus the temperature of the heater wire 7, and therefore the temperature of the heating cloth 1, is controlled to be constant.

In this way, in this embodiment, the resistance change due to temperature of the detection wire 9 is used to control the temperature of the electric heating cloth 1, and the impedance change of the nylon 8 is not used as in the conventional case. There is no inconvenience such as when the temperature control does not work as expected due to the influence. In addition, in conventional control using impedance changes, various design values in the circuit had to be changed depending on the difference in power supply frequency, for example between 50Hz and 60Hz, but this embodiment eliminates such necessity. Nor.

The sensing wire 9 serves, on the one hand, to produce the sensing voltage V1 to be sent to the heater temperature control device 13 as described above, and on the other hand to generate the sensing current to the safety device 15 shown on the left side of the transformer TR in FIG. It also functions to flow A1. Safety device 1
5 is diode D1, Zena diode RD1
and a series circuit consisting of resistors R4 and R5 connected in series to the detection line 9, a thyristor SCR1 whose gate terminal is connected to the series circuit, a resistor R3 connected in series with the thyristor SCR1, and a resistor R3. It has a temperature fuse TF as a current cutoff element which is arranged mechanically close to the resistor R3 and is blown by the heat generated by the resistor R3. The temperature fuse TF is arranged in the power supply path of the heater wire 7.

In this embodiment, nylon 8 does not play a particularly important role in controlling the temperature of the heater wire 7. However, as the temperature of the heater wire 7 increases, the impedance of the nylon 8 decreases, and a portion of the current flowing through the heater wire 7 flows into the detection wire 9 through the nylon 8, resulting in a detection current A.
1 and flows into the safety device 15. This current A
1 exceeds a certain value, the thyristor SCR1 is fired, and current flows through the resistor R3, causing the resistor R3 to generate heat. This heat generation causes a temperature fuse.
The TF melts and the power supply to the heater wire 7 is cut off, preventing the heater wire 7 from overheating and ensuring the safety of the electric heating cloth 1.

As described above, the detection wire 9 has the function of extracting the temperature change of the heater wire 7 as a resistance change, and the nylon 8
It performs two functions: receiving current from the heater wire 7 through changes in impedance.
Considering the case where these two functions are performed simultaneously in time, when applying a DC voltage to the detection line 9 and obtaining the detection voltage V1 based on the resistance change of the detection line 9, the detection voltage V1 is This may result in an error in the detected voltage V1 due to the influence of leakage current from the heater wire 7 flowing through the heater wire 7. This error is particularly noticeable when the nylon 8 is in a hygroscopic state. However, in this embodiment, the voltage to be applied to the detection line 9 is
The phase is approximately changed from the power supply line through the transformer TR
Since it is taken out with a 180° shift, the detection voltage V1
The effect of leakage current from the heater wire can be reduced when obtaining the temperature, and stable and accurate heater temperature control can be achieved.

Note that the diode D2 connected to the S1 side of the detection line 9 and the diode D6 connected to the S2 side of the detection line 9 are both used to assist the safety device 15 and ensure the safety of the heating cloth 1. be. what if,
If a short circuit occurs in a portion of the detection wire 9 close to the S1 side, a short circuit current flows through the diode D2, which blows the power fuse IF and prevents the heater wire 7 from overheating. On the other hand, if a short circuit occurs near the S2 side, the diode D6
A similar operation is performed by .

FIG. 4 is a diagram showing a main part of another embodiment of the present invention, specifically a modification of the heater temperature control device.
Terminal a and terminal b of this heater temperature control device 23 are connected to portion a and portion b in FIG. 3, respectively. This heater temperature control device 23
The purpose of this is to shorten the rise time until the heating cloth 1 (FIG. 1) reaches a desired temperature.

In the heater temperature control device 13 shown in FIG.
As shown in Fig. 5, when the detection voltage V1 decreases over time (curve A) and becomes below the reference voltage V2, the heater wire 7 stops generating heat at that point, and the heater wire temperature becomes as shown by curve _T1 . at that point in time (t1)
From then on, the rising gradient becomes smaller, and the temperature gradually approaches the desired temperature Td with a gentler temperature gradient. Therefore,
It takes a long time (t2) to actually reach the desired temperature.
It takes.

However, the heater temperature control device 23 shown in FIG.
In addition to the comparator 24, which has the same function as the comparator 14 in FIG. 25 are provided. The reference voltage V2 of the temperature maintenance comparator 24 is the reference voltage V2 of the comparator 14 in FIG.
It is set to the same value as 2. On the other hand, the reference voltage V3 of the start-up comparator 25 is set to an appropriately lower value than V2.

Even if the detection voltage V1 becomes lower than the reference voltage V2 of the comparator 24, if it is higher than the reference voltage V3 of the comparator 25, the firing signal will not be output from the comparator 24, but the firing signal will be output from the comparator 25. Since the arc signal is output, the heater wire 7 continues to generate heat, and as shown by the temperature curve _T2 in FIG. 5, the heater wire temperature rises at once to the desired temperature Td. The time required to drop to Td, the so-called rise time, is t3.

When the detection voltage V1 becomes lower than the reference voltage V3 of the comparator 25 (t6), the output from the comparator 25 disappears, and the transistor Tr2 arranged after the comparator 25 turns off. When transistor Tr2 turns off, the electric power previously stored in capacitor C4 becomes an ignition signal and turns off thyristor SCR3.
, which turns off the transistor Tr ₁ connected to the output line of the comparator 25. Once the thyristor SCR3 is fired, the thyristor SCR3 maintains that state from then on, so the detection voltage V1 becomes larger than the reference voltage V3 of the comparator 25 again (at time t4 in FIG. 5), and the output from the comparator 25 is turned off. Even if the arc signal is output, transistor Tr ₁ remains off, so the arc signal is output to the thyristor.
The SCR 2 (FIG. 3) is not ignited, so the heater wire 7 does not generate heat, and the heater temperature T2 decreases.

As the heater temperature T2 decreases, the detection voltage V1 increases, and when it exceeds the reference voltage V2 of the comparator 24 (at time t5 in FIG. 5), the comparator 24 outputs an ignition signal, and based on this signal, The heater wire generates heat, which stops the heater wire temperature from decreasing, and thereafter the heater wire temperature is controlled based on the reference voltage V2. Note that another comparator 26 is arranged after the temperature maintenance comparator 24. This comparator 26 is for compensating and stabilizing the variation in the output of the comparator 24, and for this purpose, the reference voltage V4 of the comparator 26 is set to the value of the comparator 24.
An appropriate value is selected from among the potential differences between when there is an output in 4 and when there is no output.

As is clear from the above explanation, if the heater temperature control device 23 using the start-up comparator 25 is used,
Compared to the case where the heater temperature control device 13 shown in Fig. 3 is used, the rise time is reduced from t2 in Fig. 5.
Shortened to t3. That is, electric heating cloth 1 (first
Switch SW to raise the temperature of (Fig. 3)
This is very convenient for the user, as the heating cloth 1 will rise to the desired temperature within a short time.

The heater temperature control device 23 uses the output signal of the comparator 25 as the firing signal of the thyristor SCR2 when the heater temperature rises, and uses the firing signal as the output of the comparator 24 after the temperature rises to a predetermined value. I am planning to switch to signal. The transistor Tr ₁ is used as a means for switching.
Tr ₂ and thyristor SCR 3 are used.
However, the means for signal switching could be of various circuit configurations other than those described above.

Effects As described above, according to the present invention, since the temperature of the heater is controlled based on the change in resistance of the detection wire, accurate temperature control can be performed at all times without being affected by humidity. In addition, overheating of the heater is detected based on the magnitude of the current flowing through the detection wire, and power supply to the heater is stopped based on this, so in order to detect overheating of the heater, It is economical as it does not require the use of other elements.

[Brief explanation of drawings]

Fig. 1 is an overall view of an electric heating cloth that is an embodiment of the present invention, Fig. 2 is an enlarged view of an electric heating element built into the electric heating cloth, and Fig. 3 is a heater built into the temperature controller of Fig. 1. a circuit diagram showing temperature control devices and safety devices;
FIG. 4 is a circuit diagram showing a modification of the heater temperature control device. FIG. 5 is a graph showing the relationship between detection voltage and heater temperature. SCR2...thyristor (switching element),
7... Heater wire (heater), 1... Electric heating cloth, 9...
...Detection line, 13, 23...Heater temperature control device,
TF...Temperature fuse (current cutoff element).

Claims (1)

[Claims] 1. An electric heating cloth that is equipped with a heater that is supplied with power through a switching element that switches between a conductive state and a blocked state in response to an ignition signal, and whose temperature rises due to the heat generated by the heater. A heater sheathing material that is formed of a material whose impedance changes and covers the heater; a sensing wire that is placed outside the heater sheathing material and whose electrical resistance value changes depending on the temperature; A heater temperature control device that detects a change in electrical resistance value and ignites the above-mentioned switching element, and a heater temperature control device that is placed in the power supply path to the above-mentioned heater and that detects a change in the electric resistance value and ignites the above-mentioned switching element when the current flowing through the above-mentioned detection wire exceeds a permissible value. An electric heating cloth characterized in that it has a current cutoff element that cuts off current to a power supply path.