JP2002198208A - Electronic thermostat - Google Patents

Abstract

(57) [Summary] [Problem] There is no restriction on the number of times of on / off use,
To provide an electronic thermostat that is lightweight, highly reliable, and can be used in place of a conventional mechanical thermostat. SOLUTION: A polymer-based thermistor 11 which is installed near a heater 13 to be temperature-controlled and has a positive resistance / temperature characteristic due to heat from the temperature-controlled object, and performs a switching action by an output current of the polymer-based thermistor 11. And a transistor circuit 12 for turning on / off the power supply to be temperature-controlled. Thereby, the polymer-based thermistor 11 and the switching transistor circuit 12, which have a positive resistance-temperature characteristic and whose resistance value increases rapidly when the temperature rises above a certain temperature, are small in size, light in weight, and high in reliability, and have an on-off characteristic. An electronic thermostat 10 having an unlimited number of times is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic thermostat, which has no limitation on the number of on / off times of a polymer PTC thermistor and a transistor circuit, has excellent reliability, and is suitable for temperature control of a space heater or the like. is there.

[0002]

2. Description of the Related Art Conventionally, thermostats are often used for controlling the temperature of a heater or the like, and the temperature is controlled by turning on and off the power of the heater.

In a mechanical thermostat which is one of such thermostats for controlling temperature, the temperature of a heater or the like is controlled by a function of directly turning on / off a power supply by a contact using a bimetal. In other words, when the temperature of the bimetal contact rises, the bimetal deforms and turns off the contact to stop power supply to the heater, etc., but when the ambient temperature drops, the bimetal contact turns on and power supply to the heater resumes The temperature control is performed by repeating such ON / OFF.

[0004] As another type of thermostat,
Using an NTC thermistor whose resistance decreases as the temperature rises, an electric signal obtained from the resistance value that decreases with respect to temperature is processed by an electronic circuit, and the on / off of the power supply is controlled by comparing with a set value. A centralized electronic thermostat has also been used.

[0005]

However, in the case of a mechanical thermostat, since a contact using a bimetal is directly turned on and off, an electric arc or the like is generated at the contact due to repetition of on and off, and the contact itself is deteriorated. However, there is a problem that the number of times of on / off is limited and the life is short. In particular, when used for controlling the temperature of a heater of a space device used in outer space, there is a problem that the mechanical thermostat cannot be easily replaced.

On the other hand, in the centralized electronic thermostat using the NTC thermistor, although there is no limitation on the number of on / off times, an electronic circuit for processing is required, and a control box for accommodating the electronic circuit must be installed. In particular, when it is used for controlling the temperature of a heater of a space device, there are problems of increasing the weight and securing a mounting space.

The present invention has been made in view of the above-mentioned problems of the prior art, and has no restriction on the number of times of ON / OFF use, and is small in size, light in weight and highly reliable, and can be replaced with a conventional mechanical thermostat. It is intended to provide an electronic thermostat that can be used.

[0008]

In order to solve the problems of the prior art, an electronic thermostat according to claim 1 of the present invention is installed near a temperature control target and is positive or negative by heat from the temperature control target. It is characterized by comprising a polymer thermistor having a negative resistance / temperature characteristic, and a transistor circuit which performs a switching action by an output current of the polymer thermistor and turns on and off the power supply of the temperature controlled object.

According to this electronic thermostat, a polymer thermistor which is installed near the temperature control target and has a positive or negative resistance / temperature characteristic by heat from the temperature control target, and is switched by the output current of the polymer thermistor Turns on the power of the temperature controlled object
It consists of a transistor circuit that turns off, has a positive or negative resistance / temperature characteristic, and furthermore, a polymer-based thermistor whose resistance value increases or decreases rapidly when the temperature rises above a certain temperature, and a switching transistor circuit. It aims to realize an electronic thermostat that is small, lightweight, highly reliable, and has no limit on the number of times it is turned on and off.

The electronic thermostat according to a second aspect of the present invention is characterized in that, in addition to the configuration according to the first aspect, the temperature control target is a heater for space equipment used in outer space. Things.

According to this electronic thermostat, the object to be temperature-controlled is a heater for space equipment used in outer space, and when applied to a heater for space equipment, it is small, light and reliable. The temperature can be controlled by an electronic thermostat that is expensive and has no limit on the number of on / off times.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. 1 and 2 relate to an embodiment of an electronic thermostat according to the present invention. FIG. 1 is an explanatory diagram of resistance-temperature characteristics of a polymer thermistor constituting the electronic thermostat, and FIG. It is a schematic structure figure shown with an example.

The electronic thermostat 10 is a polymer thermistor 11 installed near a temperature control target and having a positive resistance / temperature characteristic due to heat from the temperature control target.
The switching operation is performed by the output current of the polymer thermistor 11 to turn on the power supply of the temperature controlled object.
The transistor 13 is turned off and is used, for example, for controlling the temperature of the heater 13 for space equipment. The heater 13 is provided near the heater 13 and supplied to the heater 13 from a change in resistance due to the heat of the heater 13. Used to turn power on and off.

The polymer thermistor 11 constituting the electronic thermostat 10 is a polymer PTC (Po
sitive Tenperature Coefficient is a thermistor with a positive temperature coefficient. For example, as shown in FIG. 1, a device whose element temperature rapidly changes when the element temperature rises from a certain temperature. The resistance value changes from 10 to the fourth power. It extends to the sixth power.

An electronic thermostat 10 using such a polymer-based thermistor 11 has, as shown in FIG.
It is configured using the switching action of the transistor circuit 12. That is, the output current of the polymer thermistor 11 is applied to the base of the transistor 12a, and the collector current is interrupted.

As a result, when the resistance value increases due to the temperature rise and the output current of the polymer thermistor 11 decreases, the collector current turns off. Conversely, when the temperature of the polymer thermistor 11 decreases, the polymer thermistor 11 decreases. The output current increases and the collector current turns on.

Therefore, for example, when the temperature of the heater 13 for a space device is controlled by the electronic thermostat 10, the electronic thermostat 10 is provided between the heater and the heater power supply, and the polymer thermistor 11 is connected to the space device. In the vicinity of the heater 13 where the heat of the heater is transmitted.

In this state, when the temperature of the heater 13 rises and the temperature of the polymer thermistor 11 rises from a certain temperature, the resistance value sharply increases, and the polymer thermistor 11
, The collector current of the transistor circuit 12 is turned off, and the power supply to the heater 13 is stopped.

On the other hand, when the supply of electric power to the heater 13 is stopped and the temperature of the heater 13 drops and the temperature of the polymer thermistor 11 of the electronic thermistor 10 drops below a certain temperature, the resistance value sharply decreases. As a result, the output current increases, the collector current is turned on, and power is supplied to the heater 13.

The power supply to the heater 13 is turned on and off by the electronic thermostat 10 to control the temperature of the heater 13.

According to the electronic thermostat 10, the temperature at which the resistance value of the polymer thermistor 11 rapidly changes corresponds to the temperature at which the temperature of the heater 13 is controlled, so that the temperature can be controlled to the set temperature. it can.

In the electronic thermostat 10, the polymer thermistor 11 and the transistor circuit 12
Since there is no mechanical contact such as bimetal, there is no limitation on the number of times of on / off use, and it can be used repeatedly for a long period of time.

Further, in the electronic thermostat 10, the polymer thermistor 11 and the transistor circuit 12
Can be housed in a small case, and can be mounted and used without affecting other parts by wiring the heater directly to the part that performs temperature control in the same way as a conventional mechanical thermostat. In addition to being easy, there is no need to install one control box as in the case of a centralized electronic thermostat.

Therefore, by using the temperature control of the heater 13 for the space equipment used in the outer space, the temperature control with high reliability can be performed without limitation of the number of times of ON / OFF use.

The transistor circuit is not limited to the transistor circuit 12 described in the above embodiment, but may be another transistor circuit that performs switching by utilizing a rapid change in resistance value of the polymer thermistor 11 due to temperature.

The polymer thermistor is not limited to a polymer thermistor having a positive resistance / temperature characteristic, and a transistor having a negative resistance / temperature characteristic may be used to change the transistor circuit.

[0027]

According to the electronic thermostat according to the first aspect of the present invention, as described above in detail together with the embodiment, the electronic thermostat is installed near the temperature control target and is controlled by heat from the temperature control target. Or a polymer thermistor having a negative resistance / temperature characteristic, and a transistor circuit which performs a switching action by the output current of the polymer thermistor and turns on and off the power supply of the temperature controlled object. A polymer-based thermistor and switching transistor circuit that have a negative resistance-temperature characteristic and the resistance value increases or decreases rapidly when the temperature rises above a certain temperature. An electronic thermostat without the above can be realized.

Further, according to the electronic thermostat according to the second aspect of the present invention, the temperature control target is a heater for space equipment used in outer space.
Applied to heaters for space equipment, it is small and lightweight, has high reliability, and can control the temperature with an electronic thermostat with no limit on the number of on / off times.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a resistance-temperature characteristic of a polymer thermistor constituting an electronic thermostat according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing an electronic thermostat according to an embodiment of the present invention, together with an example of a circuit of the electronic thermostat.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Electronic thermostat 11 Polymer thermistor 12 Transistor circuit 13 Heater for space equipment

Claims (2)

[Claims] 1. A polymer thermistor which is installed near a temperature controlled object and has a positive or negative resistance / temperature characteristic by heat from the temperature controlled object, and performs a switching action by an output current of the polymer thermistor to perform a switching operation. An electronic thermostat comprising a transistor circuit for turning on / off a target power supply. 2. The temperature control object is a heater for space equipment used in outer space.
Electronic thermostat as described.