For a long time, in the electronics industry, thermostat is developing rapidly. Because of the flexible control of the start-stop and indoor temperature of air conditioning units in various regions and the saving of building space and engineering cost, the fan coil unit (FCU) plus fresh air air air air conditioning system has always been the preferred semi-centralized air conditioning system for hotels, hotels and office buildings which mainly rent rooms by guest rooms and commercial methods. The room air conditioning temperature controller is the key to control the cooling/heat of the terminal unit, the fan coil unit (FCU), and to realize the temperature control of the compartment and the energy-saving operation.
The general fan-coil air conditioning temperature controller is basically an independent closed-loop temperature regulation system, mainly composed of temperature sensor, two-bit controller, temperature setting mechanism, manual three-speed switch and heat and cold switching device. The control principle is that the air conditioning temperature controller controls the switch of the electric water valve (two-way valve or three-way valve) in the hot and cold water circulation pipeline by two-bit control signal based on the comparison between the room temperature measured by the temperature sensor and the set value. That is to say, the air supply temperature (cooling capacity) is regulated by cutting off and opening the water circulation in the coil.
The first generation of air-conditioning thermostats are mainly electrical products. The temperature sensors of air-conditioning thermostats adopt bimetal sheets or pneumatic thermostats. The pre-tightening force is adjusted by "given temperature plate", and the three-speed switch and seasonal switch of fan are splashed mechanical switches. Such air-conditioning thermostat products generally exist such problems as "too coarse temperature setting indexing value", "too large time constant" and "easily damaged mechanical switches".
The second generation of air conditioning temperature controller is an electronic product. Temperature sensor adopts thermistor or thermal resistance. Temperature setting and wind speed switch of some products realize man-machine interaction interface through touch keys and LCD screen. The cold and hot switching is completed automatically. The operation amplifier circuit and switching circuit realize two-bit adjustment. This kind of intelligent air-conditioning temperature controller improves the man-machine interface and solves the problem of "too rough temperature setting index", but there are still some problems such as "low control accuracy", "large time constant" and "complex operation".
At present, domestic and foreign manufacturers are researching and developing the third generation intelligent room temperature air conditioning temperature controller. Each manufacturer actively responds to the national policy and applies the new control model and CNC chip to realize intelligent control. Now domestic manufacturers have produced intelligent temperature controller for room temperature air conditioners and have been applied to practical projects. This production drives the development of the electronics industry.