JPH0447845B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heating device for direct current power supply that heats the seats, beds, etc. of a car.

A conventional heating device for a direct current power source of this type was constructed as shown in FIG. This example shows a car seat heater that heats the seats of a car. That is, in this FIG. 1, 1 is the seat seat, 2
3 is a heater wire that heats the seat and the back sheets 1 and 2; 4 is a thermostat that is embedded between the seat and the back sheets 1 and 2 and that controls the temperature of the heater wire 3; 5 is a connector for connecting a lead wire 6 to a car battery. However, in the conventional configuration described above, since the thermostat 4 is activated by detecting the temperature at one point, it is not possible to detect local overheating in other parts. If the seat sheet 1 is covered with a cushion, only the area between the cushion and the seat sheet 1 will be overheated, and as a result, the thermostat 4 will not operate and accurate temperature control will not be possible. Not only was there a risk of a fire, but there was a risk of a fire.

The present invention solves the above-mentioned conventional drawbacks, and aims to perform highly accurate temperature control and fire prevention by detecting overheating in all parts of the heater wire and performing appropriate temperature control. It is something.

To achieve the above object, the present invention provides a tubing heater in which a heater wire and an electrode wire are wound through an electronically conductive or ionically conductive temperature-sensitive material to form a tube shape, and a tubing heater in which the heater wire is in a non-energized state. A comparison circuit that detects the resistance value between the heater wire and the electrode wire and compares it with a reference value, and a timer circuit that maintains the energized state of the heater wire for a certain period of time based on the output of the comparison circuit. It is.

According to the present invention, with the above configuration, when the temperature of the heater wire is lower than the set temperature, the resistance value of the temperature-sensitive material is small, and therefore, when the heater wire is not energized, the comparison circuit Then, when it is determined that the detected resistance value is smaller than a set value, the timer circuit is energized by the output of the comparison circuit to energize the heater wire;
After the temperature has been raised to the set temperature and the timer time of the timer circuit has elapsed, the heater wire is returned to the non-energized state, but if the set temperature has not yet been reached at that point, the comparing circuit causes the heater wire to be turned off. is reversed again and the heater wire is repeatedly turned on for a limited time until the set temperature is reached, and if the temperature of the heater wire exceeds the set temperature or a part of the heater wire is overheated. In this case, the comparator circuit detects a decrease in the resistance of the temperature-sensitive material and stops re-energizing the timer circuit, so that re-energization of the heater wire is stopped and the temperature of the heater wire is set. The resistance of the temperature-sensitive material has an equivalent circuit that is connected in parallel between the heater wire and the electrode wire, so some resistance becomes small due to local overheating. Even in the case where the heater wire has deteriorated, the resistance value detected between the heater wire and the electrode wire also decreases, and as a result, local changes can be detected sensitively.

In other words, the above action allows temperature control to be performed by comprehensively monitoring the entire surface of the heating area where the heater wires are installed, making it possible to perform highly accurate temperature control and to be less sensitive to local overheating. Since the temperature can be lowered by the reaction, safety in terms of fire prevention is dramatically improved.Furthermore, the heater wire temperature can be determined by detecting the resistance of the temperature-sensitive material when the heater wire is not energized. Since it has a configuration in which the resistance value is detected without being affected by the potential gradient of the heater wire, it has various excellent features such as being able to detect the temperature with high accuracy.

An embodiment of the present invention will be described below with reference to FIGS. 2 to 5.

FIG. 2 shows a structural diagram of the tubing heater used in the present invention, where 7 is a core thread, 8 is an electrode wire wound on the core thread 7, and 9 is the electrode wire 8.
This temperature-sensitive material 9 has electronic conductivity or ionic conductivity. 10 is a heater wire wound on the temperature-sensitive material 9, and 11 is an insulating coating that covers the entire surface of the heater wire 10. Note that, depending on the structure of the tubing heater, the electrode wire 8 and the heater wire 10 may be interchanged, or the inner wire may be unwound and may also serve as a core thread. etc., and is not limited to the example shown in FIG.

FIG. 3 is a temperature characteristic diagram of the resistance value of the temperature-sensitive material 9 detected between the electrode wire 8 and the heater wire 10, in which the horizontal axis shows the temperature T and the vertical axis shows the resistance value R.

FIG. 4 is an electric circuit diagram of the present invention, and FIG. 5 is a waveform diagram of the potential of important parts in the electric circuit diagram. In FIG. It is. 13 is a heating switch, 14 is a comparison circuit, and this comparison circuit 14 is
Resistors 15 to 17 that constitute a bridge together with the resistance of the temperature-sensitive material 9, a variable resistor 18 that varies the reference potential _VS , an operational amplifier 19 that compares the potential _VD of the temperature-sensitive material 9 with the reference potential _VS , It is composed of a capacitor 20 for noise prevention and for setting heater wire non-energization time, which will be described later. Reference numeral 21 denotes a timer circuit, which includes a capacitor 22 that determines the timer time, a charging resistor 23, resistors 24 and 25 that hold a reference potential V ₀ , a discharging resistor 26 and a diode 27, and the capacitor 22. an operational amplifier 28 that compares the potential V _C and the reference potential V _O , a diode 29 as an input fixing means, and when the output V _A of the operational amplifier 28 is Hi, the potential V _D of the temperature sensitive material 9 is reduced to the power supply voltage. a diode 30 to increase the output resistance 31 of the operational amplifier 28;
and a transistor 32 that turns on when the output potential V _A of the operational amplifier 28 is Hi to supply current to the heater wire 10 .

The operation of the circuit configuration shown in FIG. 4 will be explained. When the heating switch 13 is in the ON state,
When the temperature of the heater wire 10, that is, the temperature of the temperature-sensitive material 9 is higher than the set temperature, the potential V _D of the temperature-sensitive material 9 and the reference potential V _S become V _D >V _S , and the temperature of the operational amplifier 19 Output is Low. Therefore, the potential V _C of the capacitor 22 and the reference potential V _O are V _C <V _O , and the output potential V _A of the operational amplifier 28 is also
Since it is low, the heater wire 10 remains de-energized and its temperature decreases. Therefore, the potential V _D of the temperature sensitive material 9 gradually decreases, but when the temperature of the heater wire 10 falls below the set temperature, the potential V _D of the temperature sensitive material 9 and the reference potential V _S become V _D <V _S. , the output of the operational amplifier 19 is inverted to Hi. in this case,
By selecting the resistor 26 << the resistor 23, the potential V _C of the capacitor 22 also becomes Hi,
Since V _C > V _O , the output of the operational amplifier 28
V _A also becomes Hi, and the (+) side of the capacitor 22 is fixed to Hi via the diode 29.
In other words, the output V _A of the operational amplifier 28 is once Hi.
Then, the output of the operational amplifier 19 becomes
Even if it becomes Low, the (+) of the capacitor 22
The side potential is maintained at Hi, and the capacitor 22 continues to be charged via the resistor 23. At the same time,
The capacitor 20 is rapidly charged by the diode 30, the potential V _D of the temperature sensitive material 9 is raised to Hi state, and the output of the operational amplifier 19 is turned off again.
Set it back to Low. At the same time, the transistor 32 is turned on, and the heater wire 10
energize and raise the temperature. Said capacitor 2
2, its potential V _C decreases as it charges, but
The potential V _C of this capacitor 22 and the reference potential V _O are V _C
<V _O , the output of the operational amplifier 28
Since V _A returns to Low and the diode 29 becomes reverse biased, the accumulated charge in the capacitor 22 is rapidly discharged through the resistor 26 and diode 27, and the output of the operational amplifier 19 becomes Hi. stand by. At the same time, the diode 30 also becomes reverse biased, and the potential of the temperature sensitive material 9 decreases.
V _D rapidly decreases and returns to the potential determined by the resistance of the temperature sensitive material 9 and the resistor 15 . If the detected temperature is still lower than the set temperature when the potential V _D of the sensitive material 9 returns, the operational amplifier 19
The output of returns to Hi and the timer circuit 2 is activated again.
1 and repeatedly energizes the heater wire 10 to raise the temperature to the set temperature. The diode 30
By setting the discharging time of the capacitor 22 to be shorter than the time required for the voltage V _D of the temperature sensitive material 9 to fall and the output of the operational amplifier 19 to return to Hi again, the timer circuit 21 becomes reverse biased.
Accurate timer time can be obtained every time even if the timer is repeatedly energized. If the detected temperature becomes higher than the set temperature when the timer time ends and the potential V _D of the temperature sensitive material 9 returns, the temperature sensitive material 9
The relationship between the potential V _D and the reference potential V _S is maintained as V _D > V _S , and the output of the operational amplifier 19 is maintained at Low.
The heater wire 10 is de-energized and the heater wire 10
Wait until the temperature drops to the set temperature. In this way, the temperature of the heater wire 10 is controlled to the set temperature. However, when the heater wire 10 is energized, a potential gradient occurs in the heater wire 10, so if you try to detect the resistance of the temperature-sensitive material 9 in that state, the portion of the DC power source 12 near the ground side In other words, it becomes impossible to determine the resistance on the side connected to the timer circuit 21, and uniform temperature detection is not possible. However, in the configuration of the present invention, even when the temperature of the heater wire 10 is lower than the set temperature, Since the heater wire 10 is forcibly provided with a non-energized time when the timer circuit 21 returns, and the temperature is detected during that time, highly accurate temperature detection and control can be achieved. By setting the above-mentioned timer time to a short value in a device with a fast response, it is possible to almost eliminate fluctuations in the controlled temperature. Further, when the detected temperature is much lower than the set temperature, in order to efficiently energize the heater wire 10 by repeatedly operating the timer circuit 21 and to speed up the rise, the operation time of the timer circuit 21 must be Compared to the above, it is only necessary to set the non-energizing time of the heater wire 10, that is, the time required for the potential V _D of the temperature sensitive material 9 to return from the Hi state to the normal potential and the operational amplifier 19 to invert, to be very short. This makes it possible to obtain a rise that is almost the same as continuous energization.

As described above, the heating device for DC power supply of the present invention has the following features:
A tubing heater is constructed by winding a heater wire and an electrode wire through an electronically conductive or ionically conductive temperature-sensitive material to form a tube shape. It has a comparison circuit that detects the resistance value of the hot material and compares it with a reference value, and a timer circuit that maintains the energized state of the heater wire for a certain period of time based on the output of the comparison circuit, and the heater wire, i.e. When the temperature of the temperature-sensitive material is lower than the set temperature, the time limit timer circuit is energized to energize the heater wire to raise the temperature, and when the timer circuit returns, the heater wire is turned off. When power is applied, the temperature of the temperature-sensitive material is instantaneously detected again by the comparison circuit, and if the temperature is higher than the set temperature at that time, the timer circuit is not energized and stands by, and if it is still lower than the set temperature, Since the temperature is controlled to the set temperature by repeatedly reenergizing the time limit timer circuit, the device has various excellent features as described below.

(1) The temperature can be controlled by comprehensively monitoring the entire surface of the heating area where the heater wires are installed, making it possible to control the temperature with high precision.

(2) The resistance of the temperature-sensitive material has an equivalent circuit connected countless times in parallel between the heater wire and the electrode wire, so even if some resistance becomes small due to local overheating, Accordingly, the resistance value detected between the heater wire and the electrode wire also decreases,
As a result, local overheating can be detected sensitively,
Safety in terms of fire prevention is dramatically improved.

(3) When the heater wire is not energized, that is, when no potential gradient is generated in the heater wire, the resistance value of the temperature-sensitive material between the heater wire and the electrode wire is determined and the temperature is detected, so the resistance value can be determined. can be carried out accurately, and therefore temperature detection accuracy is increased.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a conventional heating device for DC power supply.
Figure 2 is a perspective view showing the structure of the tubing heater used in the heating device for DC power supply of the present invention;
The figure is a temperature-resistance characteristic diagram of the same tubing heater, Figure 4 is an electric circuit diagram of the same DC power supply heating device, and Figure 5 is a waveform diagram of the main part potential in the electric circuit diagram of Figure 4 above. . 8... Electrode wire, 9... Temperature sensitive material, 10... Heater wire, 12... DC power supply, 14... Comparison circuit, 21
...Timer circuit.

Claims (1)

[Claims] A tubing heater configured in a tube shape by winding a heater wire and an electrode wire through an electronically conductive or ionically conductive temperature-sensitive material; A heating device for a DC power source, which is provided with a comparison circuit that detects the resistance of the material and compares it with a reference value, and a timer circuit that maintains the energized state of the heater wire for a certain period of time based on the output of the comparison circuit.