JP2016071993A - Temperature control system for electric heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a temperature control system for an electric heater capable of optionally performing self temperature control at a target temperature.SOLUTION: The temperature control system for a heater 1 includes the heater 1, a temperature sensor 2 and a power unit that gives power to the heater 1. While using a power source that is controlled so as to supply power corresponding to output from the temperature sensor 2 in accordance with a program, the power unit gives rapid increase of an electroresistance value within a predetermined temperature range to a heating temperature of the heater. When the heating temperature is lower than the target temperature, the program of the power unit gives fixed power to the heater 1 until the heating temperature becomes closer to the target temperature. When the heating temperature is higher than the target temperature, the program maintains the heating temperature by constantly supplying low power.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electric heater temperature control system for maintaining a constant heat generation temperature of various electric heaters.

  We may need an electric heater (hereinafter simply referred to as “heater”) that maintains a constant heat generation temperature close to the human body and a low heat generation temperature close to room temperature that is not far from the ambient temperature. If accurate heat generation temperature is not required, various wattage heaters can be used by switching, or when heat generation temperature accuracy may be coarse, a Robert Shaw thermostat (Robert Shaw Control using a bimetal switch or liquid expansion) Company name).

  In addition, when maintaining a constant heat generation temperature accurately, a technique for controlling the heat generation temperature of the heater to be constant using a control device is also widely used.

  However, when the target temperature is close to the environmental temperature, in order to control the temperature within a temperature range of about 0 ° C. to 40 ° C. in the conventional technology, a method of simultaneously controlling both by heating with a heater and cooling with a heat pump or the like. Adopted. This is because, in such a temperature range, the heater supplied with power rises in temperature toward the target temperature, but even if the power is cut close to the target temperature, the heat generation temperature rises past the target temperature. So-called overheating overrun occurs. In order to cope with this overheating overrun, it is cooled by a heat pump. However, the current technology is that the heating by the heater and the cooling by the heat pump are finely balanced and controlled near the target temperature. Therefore, since the temperature control in the above-mentioned temperature range necessitates a cooling device, there are many cases where it is practically impossible to use the conventional technology. For example, for clinical use, the stub and noise of the refrigerator are hindered. It may also be difficult to place a refrigerator between the intricate research devices.

  On the other hand, a self-temperature adjusting heater using the physical properties of the heater itself is also used without using a control device. One is a barium titanate ceramic heater (for example, Patent Document 1), and the other is a carbon-crystalline polymer heater (for example, Patent Document 2). In either case, the resistance value rapidly increases when the heat generation temperature of the system exceeds a threshold value. Barium titanate ceramic heaters increase in resistance at exothermic temperatures of 100 ° C or higher. In the case of a carbon-crystalline polymer heater, the exothermic temperature is almost 50 ° C. to 100 ° C., and it is difficult to give the exothermic temperature within the aforementioned temperature range of 0 ° C. to 40 ° C.

  Create a self-regulating heater with a constant exothermic temperature within the temperature range obtained by dispersing carbon using paraffin, low molecular weight polyethylene glycol, etc., which has a melting point near the desired exothermic temperature instead of a polymer. The inventor has been making various proposals for a long time by examining it (for example, Patent Document 3, Non-Patent Document 1, etc.). However, if the heater is exposed to an environmental temperature higher than the steady exothermic temperature after fabrication, the system will be dissolved, which is practically impossible with such a system.

JP 09-045504 A Japanese Unexamined Patent Publication No. 2005-093735 JP 2004-172611 A

J. Appl, Phys., 59, 960 (1986),

  In order to accurately maintain the desired fever temperature in the vicinity of the fever temperature that is close to the ambient temperature and body temperature, the current technology has nothing but a technology that uses a cooling device to control both overruns mutually. . If the cooling device cannot be brought in, there is no means at all.

  The above-described self-temperature-controlled heating element based on a system using low melting point paraffin or polyethylene glycol cannot be denied as a possibility for the aforementioned temperature control. However, when the exothermic temperature is higher than the melting point, the system melts, and even if it is solidified again, the resistance value changes drastically, causing a problem in using it as it is. In addition, heaters based on such systems are brittle and fragile, and thus have practical problems.

  Therefore, a heater capable of permanently maintaining the exothermic temperature by reaching a desired exothermic temperature in a temperature range including a normal temperature range of 0 ° C. to 40 ° C. in a short time without any cooling device. With the development of the temperature control system, it is an object to obtain a control device that can select and use whatever heater has the desired properties (robustness, flexibility, flexibility, soft texture).

  In order to solve these problems, the present invention is a heater temperature control system capable of self-temperature control arbitrarily at a target temperature, and includes a heater, a temperature sensor, and a power device for supplying power to the heater. The power unit uses a power supply that is controlled by a program so that power corresponding to the output from the temperature sensor is supplied, and suppresses power within a specified temperature range with respect to the heat generation temperature of the heater to keep the heat generation temperature constant. A temperature control system for a heater, characterized in that an appropriate power is supplied for control.

  In a heater in which carbon is dispersed in a polymer, polyethylene glycol, paraffin or the like to make the system conductive, the heating temperature of the system rises due to Joule heat when energized. If the components other than carbon are crystalline, there is a sudden change in density in the vicinity of their melting points, which leads to a rapid increase in electrical resistance. This is a conventional self-temperature adjusting heating element. The melting point of the system is an inherent property of the substance, and it is not easy to select a substance having a desired melting point. However, if a program capable of performing appropriate power control in a predetermined temperature range using a certain kind of electric control for a general heater is used, the heat generation temperature can be controlled. The power device for that purpose may use a power source controlled so as to be supplied with electric power according to the output from the temperature sensor by a program.

  In the current technology, in order to maintain the heat generation temperature close to the environmental temperature, heating by a heater and cooling by a heat pump (such as a refrigerator) are simultaneously operated to control the balance between them. The present invention does not use any cooling system even when the target temperature is close to the ambient temperature. However, the exothermic temperature at which equilibrium is achieved by the present invention may not be close to the ambient temperature. Any exothermic temperature can be controlled. Since this power device does not include any cooling device, it is not possible to set the heat generation temperature below the ambient temperature as the target temperature. In such a case, no power is supplied to the heater. If the target temperature is higher than the ambient temperature, the proper power is supplied to the heater, and this is maintained after reaching the target temperature. It does not matter if the target temperature is much higher than the ambient temperature.

  The power device of the present invention applies a voltage when the heating temperature of the heater is lower than the target temperature, and gradually lowers the voltage applied as the heating temperature approaches the target temperature, as shown in FIG. When the heat generation temperature approaches the target temperature, the degree of voltage decrease is increased, and when the heat generation temperature exceeds the target temperature, the voltage is further decreased. When the exothermic temperature exceeds the target temperature, the voltage applied to the heater need not be zero. Since the power (energy) given to the heater is proportional to the square of the voltage, even if the voltage drops to 1/10 of the initial value, the power drops to 1/100 of the initial value. This is because even when a voltage is applied, the heat generation temperature of the heater does not increase substantially.

  In order to maintain a constant heat generation temperature according to the present invention, basically any heater may be used. Regardless of the heater, an output control device corresponding to the allowable current of the heater may be used. If it is a small heater, the control device can be smaller than the remote control of the television. For large-scale snow melting and agriculture, a larger size is required. Even if the heater is small, if the heat generation temperature is confined within a very small temperature range, the control device will be somewhat larger.

  The heater can be used in various forms such as a planar shape, a linear shape, a rod shape, and a block shape depending on the application, but a general-purpose shape is a planar heating element. The heater is a cloth-like heater formed by knitting thin electrical resistance wires together with plant or synthetic resin fibers. In some cases, the heater is preferably finished to a sheet covered with an insulating sheet or insulating film.

  It is clear that by using the heater temperature control system according to the present invention as described above, it is possible to maintain a constant heat generation temperature of 40 ° C. or lower, which was impossible without a conventional cooling device. Became. Therefore, even when the target temperature of the temperature-controllable heater is close to the environmental temperature, the temperature control system does not require the use of any cooling system. Further, by adjusting the parameters of the program of the power device, a desired steady heat generation temperature can be maintained.

  In the prior art, if a low melting point material was used, there was a possibility of a self-temperature-regulating heater at a low exothermic temperature. However, as described above, if the heater is made of such a low melting point material, the vulnerability of the heater itself cannot be avoided. However, in the present invention, since a heater having characteristics such as sufficient strength and flexibility that is satisfactory in practical use can be used, self-temperature adjustment with high safety and reliability as well as durability can be performed.

It is a block diagram which shows the internal structure of the electric power apparatus used for the temperature control system of the heater which can perform self temperature control by the target temperature which concerns on this invention. This is a temperature resistance characteristic of a conventional self-regulating heater using polyethylene glycol (# 1540). 2 shows an example of a relationship between temperature and output power when power control is performed by a heater temperature control system according to the present invention. 5 is a graph showing the relationship between the energization time and the heat generation temperature in a state of maintaining a temperature at a low heat generation temperature using the heater temperature control system of the present invention for a planar heater knitted with a normal thin resistance wire. It is the perspective view which showed a mode that the heat_generation | fever temperature of the heater by this invention was measured.

  Conventional self-regulating heating elements incorporating paraffin or polyethylene glycol having a low melting point in the system have a large problem in practical use as described above. However, the electrical properties of these systems, ie the temperature resistance characteristics, are interesting. The temperature resistance characteristics of the system using polyethylene glycol (# 1540) are shown in FIG. FIG. 2 shows the temperature resistance characteristics of a conventional self-regulating heater using polyethylene glycol (# 1540). When this heater has an exothermic temperature higher than the melting point of polyethylene glycol, its characteristics change greatly due to melting. It is known that the temperature of the self-regulating heating element using this system is covered with a hot insulator and the upper part is covered with a thin insulator, the exothermic temperature is measured, and the constant exothermic temperature is maintained at about 36 ° C. .

  Aside from the weakness of the self-temperature adjusting heater using polyethylene glycol described above, it is not possible to freely manufacture a heater with a constant exothermic temperature of several degrees Celsius or below. This is because it is difficult to easily obtain substances having such physical properties.

  Therefore, in the present invention, instead of searching for a material system having physical properties similar to those in FIG. 2, an arbitrary heater is used to provide a heater temperature control system that provides the same effect as in FIG. Decided to develop. That is, in the conventional self-temperature control heater, when the heat generation temperature increases, the resistance value increases and the wattage decreases to reach a constant temperature. However, in the present invention, the voltage applied to the heater nears the target temperature. Is controlled near the target temperature and maintains a constant exothermic temperature. In both cases, the relationship between heat generation temperature and wattage is almost the same.

  The internal configuration of the power device used in the temperature control system capable of controlling the temperature at the target temperature according to the present invention can be shown in the block diagram shown in FIG. In FIG. 1, the output of the temperature sensor 2 in contact with the heater 1 is measured, the analog signal of the output is linearized and amplified by the sense amplifier 3, and then converted into a digital signal by the input A / D converter 4. Input to the computer 5 to recognize the heating temperature of the heater. The microcomputer 5 calculates the heater output corresponding to the heat generation temperature. Then, a digital signal as a calculation result is converted into an analog signal by the output D / A converter 6 and input to the DC power source 7, and a DC voltage matching the heater output is applied to the heater 1 from the DC power source 7. The heating temperature of the heater measured by the temperature sensor 2 is output to the SD card 8, for example, and stored. The current output from the DC power source 7 is output as a digital signal to the microcomputer 5 via the monitoring A / D converter 9 and monitored.

  The temperature control system shown in FIG. 1 is configured so as to give a steady heat generation temperature that is almost the same as that of the conventional self-temperature adjusting heat generator shown in FIG. The relationship between the heat generation temperature measured by the temperature sensor 2 (see FIG. 5) and the output voltage of the power device is shown in FIG. The heater 1 incorporating the resistance wire 13 (see FIG. 5) was connected to the temperature control system and energized. FIG. 4 is a graph showing a state of maintaining the temperature at a low temperature using the temperature control system of the present invention for the heater 1 in relation to the energization time and the heat generation temperature. It can be seen that the heating temperature of the heater 1 approaches the target temperature 30 minutes after being energized, and has maintained a constant heating temperature after 1 hour. This is shown in Example 1 described later.

  Here, the present invention is compared with the prior art again. First, the conventional control technology (not including the conventional PTC heater) and the present invention will be discussed. In the conventional control technology, it is necessary to control both by heating with a heater and cooling with a refrigerator near the environmental temperature. This unnecessary technology of the refrigerator according to the present invention promises new advances in the fields of medicine, biotechnology and the like. In other words, it may not be possible to install a freezer in clinical research or precise bio research. Research, technology, industry, etc., in which temperature control according to the present invention has been impossible until now, can be made possible. However, in the present invention, only the heat generation temperature near the environmental temperature is not a problem. As long as the target temperature exceeds the ambient temperature, the target temperature can be maintained with only the heater. Of course, it is possible to set the heat generation temperature when the temperature is much higher than the environmental temperature.

  Next, the present invention is compared with a conventional PTC heater. Conventional PTC heaters cannot select a steady heat generation temperature freely. However, in the present invention, it is possible to freely select a steady heat generation temperature only by changing the setting of a program for controlling the power output from the power supply or the parameter (variable). Further, the stability and fastness of the heater itself are superior in the case of the present invention. In the conventional PTC heater, the exothermic temperature at which the resistance value increases rapidly is close to the layer transition temperature of the matrix, so that the heater becomes brittle near the layer transition temperature. On the other hand, in the present invention, any heater can be used, so that a robust one can be selected.

  As shown in the perspective view of FIG. 5, the heater 1 to be measured has a cloth shape in which a resistance wire 13 is knitted, and is a square in plan view having a size of 160 mm × 160 mm to which the lead wire 10 is connected. The bottom surface of the heater 1 is provided with a 50 mm thick styrene foam insulating plate 11, the temperature sensor 2 is set on the heater 1, and the top surface is covered with a 5 mm thick foamed polyethylene sheet (not shown). It was. FIG. 3 shows an example of self-temperature control when a low temperature control parameter (variable) is set in the power device of the heater temperature control system of the present invention.

  FIG. 3 shows an example of a temperature-negative / voltage relationship when power control is performed by the heater temperature control system according to the present invention. In addition, as a result, the relationship between the energization time and the heat generation temperature as shown in FIG. 4 is obtained. Even in the heater 1 in which the normal thin resistance wire 13 is knitted, the low temperature of about 35 ° C. is obtained using the present invention. The result shows that the exothermic temperature can be maintained, and the exothermic temperature approaches the target temperature 30 minutes after energization, and the constant exothermic temperature is maintained even after 5 hours from 1 hour. I understand.

  The most promising field of the present invention is medicine. It is generally known that immunity increases with increasing body temperature. However, there has been virtually no heater that maintains an exothermic temperature of, for example, 2 ° C. above body temperature. Also, anyone can admit that thermotherapy for cancer is also an effective means, but until now there has been no effective technique. There are many other applications in the medical field.

  There are many expectations in the field of biotechnology. It can be said to be an indispensable means for tissue culture and visualization of cell growth processes. Although biotechnology and medicine overlap, a new research result is expected because temperature control, which has been complicated in the past, can be performed with only one heater.

  There are many fields of application in agriculture. When trying to produce mushrooms in winter, there was a limit that should not exceed 20 ℃. This can be achieved by using the present invention. Moreover, as is generally said, it is said that as long as the plant is not frozen, only the “root” needs to be warmed. At present, development of heaters for "roots" is being attempted in some areas, but unfortunately it has not been successful. If the present invention is applied to this field, it is thought that the consumption of heavy oil by house farmers will be reduced.

  There are many outdoor applications of the present invention. For example, snow melting and freezing prevention. In this case, the heating temperature of the heater should be 5 ° C. Some use carbon-polymer heaters (organic heaters) for floor heating for melting snow. These organic heaters change their resistance values when exposed to high temperatures in the summer. There is a high possibility that it will become unusable in that year. In the present invention, a robust inorganic heater can be used, and there is no problem with steady heat generation at 5 ° C. in winter. This has many possibilities, including winter bridges, roads, airfield parking lots, runway prevention, and snow melting on Shinkansen bodies. Further, when the present invention is applied to a heater that melts snow adhering to the Shinkansen, it is not necessary to reduce the traveling speed, so that the diamond can be prevented from being disturbed.

1 Heater 2 Temperature Sensor 3 Sense Amplifier 4 A / D Converter for Input 5 Microcomputer 6 D / A Converter for Output 7 DC Power Supply 8 SD Card 9 A / D Converter for Monitoring
10 Lead wire for heater
11 Insulation plate
12 Lead wire for sensor
13 Resistance wire

Claims (5)

An electric heater temperature control system capable of self-temperature control at a desired temperature,
Consists of a power device that provides power to the heater, temperature sensor and electric heater,
The power device uses a power source controlled by a program so that power corresponding to the output from the temperature sensor is supplied,
A temperature control system for an electric heater, wherein electric power is suppressed in a predetermined temperature range with respect to an exothermic temperature of the electric heater, and the exothermic temperature is controlled to be constant. When the heat generation temperature is lower than the target temperature, the power device supplies a constant high power to the electric heater until the heat generation temperature reaches the target temperature.
2. The temperature control system for an electric heater according to claim 1, wherein when the heat generation temperature exceeds a target temperature, the electric power supplied is reduced to control the power source so as to maintain the heat generation temperature of the electric heater.   The temperature control system for an electric heater according to claim 1, wherein the electric heater is a planar heating element covered with an insulating sheet.   The temperature control system for an electric heater according to claim 3, wherein the electric heater is a cloth heater formed by knitting a thin electric resistance wire together with a plant or synthetic resin fiber.   The temperature control system for an electric heater according to any one of claims 1 to 4, wherein no cooling system is used even when the target temperature is close to the environmental temperature.