The fluid medium temperature controller realizes automatic adjustment based on the principle of thermal expansion and contraction of temperature-sensitive fluid and incompressibility of liquid. When the control temperature rises, the thrust generated by the expansion of the temperature-sensitive liquid will turn down the thermal medium to reduce the output temperature; when the control temperature decreases, the temperature-sensitive liquid shrinks. Under the action of the reset device, the thermal medium is opened to increase the output temperature, so that the controlled temperature reaches and remains within the set temperature range.
The working principle of bimetallic thermostat is based on the principle of object expansion and contraction. Thermal expansion and contraction are common to objects, but different objects have different degrees of thermal expansion and contraction. The two sides of the bimetal sheet are conductors of different substances. The bimetal sheet bends due to different expansion and contraction at different temperatures, touching the set contact or switch, and the set circuit (protection) starts to work.
The working principle of color temperature controller is that some paints will produce different colors at different temperatures. For example, using liquid crystal at different temperatures can produce different colors, and then using camera-type color collectors to provide different data for the circuit to control the circuit.
According to the manufacturing principle of temperature controller, the temperature controller is divided into:
1. Jump-type temperature controller: various types of jump type temperature controllers are collectively referred to as KSD, such as KSD301, KSD302, etc. The temperature controller is a new type of bimetallic sheet temperature controller, which is mainly used as various electric heating products with overheating protection, and is usually used in series with thermal fuse, and the jump type temperature controller is used as primary protection. The thermal fuse is used as a secondary protection device to effectively prevent the heating element from burning out and the resulting fire accident when the sudden tripping temperature controller is lost or fails, which causes the heating element to overheat.
2. Liquid-expansive temperature controller: refers to the physical phenomenon (volume change) that causes the material (usually liquid) in the temperature sensing part of the temperature controller to expand and contract when the temperature of the controlled object changes, and the capsule connected with the temperature sensing part expands or contracts. Based on the lever principle, it drives the on-off action of the switch to achieve the purpose of constant temperature. The hydraulic expansion thermostat has the characteristics of accurate temperature control, stability and reliability, small temperature difference between start and stop, large range of temperature control and adjustment, and large overload current. The hydraulic expansion temperature controller is mainly used for temperature control fields in household appliances industry, electric heating equipment, refrigeration industry, etc.
3. The pressure type temperature controller is modified to change the controlled temperature change into the change of space pressure or volume through the closed temperature bulb and capillary filled with the temperature sensing working medium. When the temperature setting value is reached, the contact will be automatically closed through the elastic element and the quick instantaneous mechanism to achieve the purpose of automatic temperature control. It is composed of three parts: temperature sensing part, temperature setting main part, microswitch for opening and closing or automatic damper. The pressure type temperature controller is applicable to refrigeration appliances (such as refrigerators, freezers, etc.) and heating devices.
4. Electronic temperature controller and electronic temperature controller (resistance type) are measured by means of resistance temperature sensing. Generally, platinum wire, copper wire, tungsten wire and thermistor are used as temperature measuring resistors. These resistors have their own advantages. Most household air conditioners use thermistor type.
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