JPH053071A - Temperature control device for electric carpet and the like - Google Patents

Abstract

PURPOSE:To detect a partial abnormal heating of an electric carpet and the like, and to carry out a safety control. CONSTITUTION:A current is fed to the heater wire 4 of a heating and temperature detecting cord 3 made by winding the heater wire 4 and a temperature detecting wire 9 each other through a heat sensitizing member 8, so as to generate a heat, and a partial abnormal heating is detected by measuring the impedance variation by the heat of the heat sensitizing member 8. The above impedance is set in two phases of temperature scopes, and an alarm is generated in the first phase, while a safety control to cut off the power source is executed in the second phase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control device for an electric heater having a sheet-shaped heat generating surface such as an electric carpet, and particularly detects partial abnormal heat generation caused by external heating, improper use, failure or the like. The present invention relates to a temperature control device such as an electric carpet that can be safely controlled.

[0002]

2. Description of the Related Art In a conventional electric heating device such as an electric carpet, a heating element 50 is laid on the entire surface of a carpet 52 as shown in FIG.
1 is laid on the entire surface, and the temperature is controlled by controlling the energization of the heating element 50 in the controller 67 by the detected temperature. FIG. 7 shows an electric circuit diagram of a conventional electric carpet.
As shown in FIG. 9, the heat generating element 50 in the figure has a heat generating wire 54 spirally wound around a heat resistant core material 53 as shown in FIG.
5, the short-circuit wire 56 is spirally wound on it, and the outer side thereof is covered with a jacket 57 made of an insulating material. Similarly, as shown in FIG. 10, the temperature sensor 51 also includes the first winding 59 wound around the core material 58 and the heat-sensitive material 6
1 and the second winding 60 is wound on it, and the outer side thereof is covered with a jacket 62. The heating element 5
The heating wire 54, which is a component of No. 0, is connected to the power source through the SCR 63, which is a switching element, as shown in FIG. 7, and when energized, heat is generated to heat the entire carpet. The temperature sensor 51 includes a heat-sensitive material 6 for interposing the heating temperature of the carpet between the first winding wire 59 and the second winding wire 60.
The temperature is detected by utilizing the fact that the impedance of 1 changes with temperature. The impedance change of the temperature sensor 51 is input to the controller 64 as a voltage change, the gate current of the SCR 63 is controlled by the controller 64 so that the carpet reaches the set temperature, and the heating wire 54 is turned on / off.
F control. The temperature control over a wide area of the carpet is performed as described above, but when the carpet is locally kept warm or is subjected to external heating, it is locally abnormally heated and the heating element 50 of that portion is heated. Is heat sensitive material 5
5 melts, an electric current flows from the short-circuit wire 56 to the heat generating wire 54, heats the heat generating resistor 65, and the thermal fuse 66 is melted by the heat, and safety control is performed to cut off the power supply to the heat generating wire 54.

[0003]

However, when an abnormality is detected in the above safety control, the heating element 50 has already been partially destroyed, and this destroyed portion cannot be regenerated, resulting in total loss due to partial damage. was there. Further, as described above, in the conventional example carpet, since the temperature sensor 51 for detecting the temperature is laid on the entire surface of the carpet in addition to the heating element 50, the temperature of the carpet is 2 on the carpet.
Since the cords of each type are individually wired, there is a problem that not only the number of irregularities due to wiring increases but also the cost of materials and processing rises. In view of the problems of the conventional example as described above, the present invention performs heat generation and temperature detection by the heat generation and temperature detection cords in which the heat generation line and the temperature detection line are wound around one cord via a heat sensitive material, and It is an object of the present invention to provide a temperature control device for an electric carpet or the like, which can be safely controlled before detecting a partial abnormal heat generation of the carpet or the like and causing damage.

[0004]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a heat generation / temperature measurement in which a heat generating wire and a temperature detecting wire are wound around each other via a heat sensitive material whose impedance changes according to temperature. A cord is laid on the entire surface of an electric carpet or the like, and the heating wire is energized to generate heat, and the impedance between the heating wire and the temperature detection wire is measured to detect partial abnormal heating of the heating wire. In a temperature control device such as an electric carpet, when the impedance enters a predetermined first temperature range, the first safety control means for interrupting the power supply to the heating wire and generating an alarm and the impedance And a second safety control means for shutting off the power supply circuit when entering a second temperature range higher than the first temperature range. And it is configured as a control device. Further, a heating temperature detecting means for controlling the temperature of the electric carpet or the like by measuring the resistance change of the temperature detecting wire,
It is configured to control switching between the temperature detecting means at the time of abnormality.

[0005]

According to the present invention, a heating / temperature detecting cord is laid on the entire surface of a carpet or the like and heated by energizing the heating wire. At the same time, by measuring the impedance change due to the temperature change of the heat-sensitive material, a partial abnormal heat generation of the heating wire can be detected. Therefore, the temperature range of this impedance change is set in two stages, and the impedance is set to the first temperature range. When it is detected that it has entered, an alarm is generated by the control circuit to prompt the user to eliminate the cause of local abnormal heat generation,
When an abnormal heat generation that exceeds the first temperature range and reaches the second temperature range is detected, the second safety control means for shutting off all power to the carpet is controlled.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment in which the present invention is embodied as an electric carpet will be described with reference to the drawings. Figure 1
Shows an electric circuit diagram of an electric carpet according to one embodiment,
Power supply 1, temperature fuse 2, heat generation / heat detection code 3, heat generation wire 4, triac 5, current fuse 6, power switch 7
Are connected in series to form a heating circuit. As shown in FIG. 2, the heat generation / temperature detection code 3 includes a heat generation wire 4 on the heat resistant core material 40.
Spirally, and cover it with heat-sensitive material 8,
The temperature detecting wire 9 is spirally wound in the opposite winding direction to the heat generating wire 4, and is covered with an insulating jacket 41 to form a double winding structure. The heat generating wire 4 generates heat when energized, and the temperature detecting wire 9 is made of a material whose resistance value changes with temperature. For example, the temperature detecting wire 9 is made of nickel or copper. In addition, it has the characteristic that the resistance value increases as the temperature rises. The fever / temperature measuring code 3 is the electric carpet 4 as shown in FIG.
Since it is laid over the entire surface of 2, the total length is 70
When m, the resistance change due to temperature at L = 70 m of the temperature detection line 9 is as shown in FIG. 3, and the resistance change due to this temperature is measured to control the heating by the heating wire 4 to the set temperature. It is used as a sensor for.

Further, the heat-sensitive material 8 interposed between the heating wire 4 and the temperature detection wire 9 is an insulating material such as nylon, and the permittivity changes with temperature, so that the heat-sensitive material 8 intervenes heat generation. The impedance between the line 4 and the temperature detection line 9 changes with temperature. As shown in FIG. 4, the impedance change due to the temperature of the heat-sensitive material 8 has a characteristic that the impedance decreases as the temperature increases. The heat-sensitive material 8 has the heat-generating / temperature-measuring cord 3 laid on the entire surface of the carpet 42, so that when the carpet 42 locally heats abnormally, the impedance locally lowers. If the impedance between the two is constantly measured, the local abnormal heat generation of the carpet 42 can be detected. The set temperature control by the temperature detection line 9 and the safety control of the local abnormal heat generation by the heat sensitive material 8 are controlled as follows. In Figure 1, C of the microcomputer 16, and C'terminal, E, and a E'terminal, the transistor _{Q 4, Q 2, Q 3} , Q 1 which operates alternately as a switching element and outputs the base drive signals ， Set temperature control and safety control are executed alternately. That, C, the output signal from the C'terminal, when the transistor Q _4, Q ₂ to ON (transistors Q _1, Q ₃
Is OFF), the temperature detection line 9 and the transistors Q ₄ and Q ₂ are connected in series, and the total resistance of the resistance value of the temperature detection line 9 and the resistance R ₂ connected to the emitter circuit of the transistor Q ₂ and the transistor Q Resistor R ₁ connected to the collector of ₄
The voltage at the connection point (A) between the emitter of the transistor Q ₄ and the temperature detection line 9 changes due to the resistance change due to the temperature of the temperature detection line 9 due to the resistance voltage division of It is input to 16 I _a terminals and is read as a temperature change value by A / D conversion.

When the input voltage to the I _a terminal of the microcomputer 16 exceeds a value corresponding to a predetermined set temperature, a control signal is output from the output terminal O ₁ of the microcomputer 16 to turn off the transistor Q _5. By doing so, the gate current of the triac 5 is stopped through the photocoupler PC ₁ connected to the emitter, and the power supply to the heating wire 4 is stopped. When the temperature of the heating wire 4 is lowered by turning off the power supply to the heating wire 4, the resistance value of the temperature detection wire 9 is lowered. Therefore, when the microcomputer 16 reads from the voltage at the point (A) that the temperature is below the set temperature, the transistor Q ₅ is turned on and triac 5 is turned on, and the heating wire 4 is energized and heated again. This set temperature can be set to a desired temperature by selecting the values of the resistors R ₁ and R ₂ . The temperature control by the temperature detection line 9 is
The cut-off control of the upper limit is performed, and the adjustment of temperature strength is performed by turning on / off the triac 5 by the transistor Q ₅ and the photocoupler PC ₁ so that the microcomputer 16 controls the zero cross ON / OFF for each cycle of the power supply frequency.
It is OFF controlled. This energization rate can be increased or decreased stepwise by the up switch 20 and the down switch 21 connected to the I ₂ , I ₁ , and I ₀ terminals of the microcomputer 16. FIG. 5 shows an example of the voltage waveform across the heating wire 4 when the duty ratio is changed, and the current applied during a unit time is intermittently controlled in frequency cycle units by setting the temperature to high, medium, or low.

Next, E of the microcomputer 16,
When there is an output signal from the E'terminal, the transistors Q ₃ and Q ₁ are controlled to be ON (transistors Q ₂ and Q ₄
Is OFF), the heating wire 4 and the temperature detection wire 9 through the heat-sensitive material 8
An AC circuit formed through the impedance and the resistance R ₃ between the DC voltage obtained by rectifying the voltage divided by the impedance and the resistance R ₃ of the heat-sensitive material 8 (B) point of the microcomputer 16 I _b terminal Entered in. Now, when the carpet 42 is partially kept warm or heated,
Since the temperature of the heat-sensitive material 8 at the set position rises and the impedance decreases compared to other parts, the voltage at the point (B) changes. The microcomputer 16 has a built-in non-volatile memory that responds to changes in impedance due to temperature changes.
The voltage region of the stage is stored. A first temperature region having a relatively low temperature and a second temperature region having a higher temperature than the first temperature region. When the abnormality of the local heating of the carpet 42 is relatively low temperature, for example, about 100 to 130 ° C., the microcomputer 16 which receives the input of the (B) point voltage at that time has the above-mentioned input voltage as the first voltage. When it is determined that the temperature is within the temperature range, a safety control signal for turning off the transistor Q ₅ is output from the output terminal O ₁ to turn off the triac 5 to stop energization of the heating wire 4 and to inform the user. The buzzer 33 for notifying the abnormality is activated to generate a warning sound. The buzzer 33 keeps this state until the cause of the abnormality is eliminated by the user, and when the user operates the reset switch 32 after eliminating the cause, the control device returns to the normal state. Return. However, if the abnormality of the local heating exceeds the first temperature range described above and enters the second temperature range where there is a risk of burns due to component damage due to external heating or local heat insulation, the (B) point voltage becomes higher. Since it becomes large, the microcomputer 16 outputs a safety control signal from the output terminal O ₂ , turns on the transistor Q _6, and turns on the photocoupler PC.
Turn on thyristor 36 through ₂ . As a result, the resistor R ₅ inserted in series with the thyristor 36 generates heat and melts the temperature fuses 2 arranged in close proximity, so that the entire power supply circuit is cut off.

As described above, the heat generation / temperature detection code 3 has three functions of heat generation, temperature detection for temperature control, and local temperature detection for safety control. The constant resistance value and the impedance change of the heat sensitive material 8 are alternately detected at all times to maintain the set temperature and execute the safety control. Incidentally, the transformer 22 in FIG.
Diode D ₁ to D _4, the capacitor C ₁ constitute a DC power source to the controller, crystal oscillator X ₁ and resistor R _4, a capacitor C _3, C ₄ constitutes a source of reference signal for control It is a thing. In the above embodiment, a specific example in which the present invention is applied to an electric carpet is shown.
It goes without saying that the present invention can also be applied to a flat electric heater such as an electric cushion that may generate local heat.

[0011]

As described above, according to the present invention, the heat generation / temperature detection code detects not only the heat generation but also the local abnormal heat generation, and the abnormal state of the electric carpet or the like is detected stepwise to thereby prevent the reproduction failure. It can be safely controlled before possible damage. Such a local abnormal heat generation is a special phenomenon in a carpet or the like which may be locally loaded or locally have furniture, furniture, etc., and the present invention is particularly suitable for such a carpet or the like. Is. Further, in the present invention, since only one heating / temperature detecting cord needs to be laid on a carpet or the like, there is less unevenness in wiring, material cost, and processing cost compared to the case where two types of cords are conventionally wired. Remarkable.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram of a temperature control device according to an embodiment.

FIG. 2 is a configuration diagram of a fever / temperature measuring code.

FIG. 3 is a resistance-temperature characteristic graph of a temperature detection line.

FIG. 4 is an impedance-temperature characteristic graph of a heat-sensitive material.

FIG. 5 is an explanatory diagram of a duty ratio control for a heating wire.

FIG. 6 is a plan view of an example electric carpet.

FIG. 7 is an electric circuit diagram of a conventional temperature control device.

FIG. 8 is a plan view of a conventional electric carpet.

FIG. 9 is a configuration diagram of a conventional heating element.

FIG. 10 is a block diagram of a conventional temperature sensor.

[Explanation of symbols]

2. Thermal fuse 3… Fever / temperature measuring code 4 ... Exothermic line 8 ... Heat sensitive material 9 ... Temperature detection line 16 ... Microcomputer 33 ... Buzzer

Claims (2)

[Claims] 1. A heating / temperature detecting cord, which is formed by winding a heating wire and a temperature detection wire around each other through a heat-sensitive material whose impedance changes according to temperature, is laid on the entire surface of an electric carpet or the like. In a temperature control device such as an electric carpet that detects partial abnormal heat generation of the heating wire by measuring the impedance between the heating wire and the temperature detection wire while energizing to generate heat, the impedance has a predetermined value. When entering the temperature range of 1, the first safety control means for interrupting the power supply to the heating wire and generating an alarm, and the second temperature range where the impedance is higher than the first temperature range are entered. A temperature control device for an electric carpet or the like, comprising: a second safety control means for shutting off the power supply circuit. 2. The electricity according to claim 1, wherein the heating temperature detecting means for controlling the temperature of the electric carpet or the like by measuring the resistance change of the temperature detecting wire and the temperature detecting means at the time of the abnormality are switched and controlled. Temperature control device for carpets.