Control method for electronic expansion valve of heat-pump water heater and control device thereof

Abstract

The invention relates to a fluid heater for utilizing a heat pump, in particular to a control method for an electronic expansion valve of a heat-pump water heater and a control device thereof. The control device of the electronic expansion valve comprises a control unit and a stepping motor, wherein the output end of the control unit is connected to the stepping motor, the output shaft of the stepping motor is connected with the electronic expansion valve, the control unit comprises a controller, a driving circuit and a group of temperature sensors, the temperature sensors are fixed in a cooling-medium circulating loop of the heat-pump water heater, and the controller comprises a target superheat-degree setting module, an actual superheat-degree detecting module, a regulating-speed setting module and a driving-signal generating module. In the invention, the exhaust temperature, the water-tank temperature and the environmental temperature are comprehensively judged, a variable target superheat degree is set, the relation of the exhaust temperature and the opening of the electronic expansion valve can be correctly identified, and the requirements of different circulating flow quantities in the state of the variable working condition of the heat-pump water heater are met, thereby the high efficiency, the safety and the stable operation of the heat-pump water heater are achieved.

Description

technical field [0001] The invention relates to a fluid heater for utilizing a heat pump, in particular to a method for controlling an electronic expansion valve of a heat pump water heater and a control device thereof. Background technique [0002] The throttling method of air source heat pump water heaters on the market now mainly uses thermal expansion valves or capillary tubes. Thermal expansion valves are adjusted according to parameters such as suction temperature and outlet pressure, which have the defects of small adjustment range and low precision. Throttle depth is not adjustable. The thermal expansion valve is mainly designed according to the working conditions of the air conditioner, and there is no thermal expansion valve specially designed for the special product of the air source heat pump water heater. The water temperature range of the air source heat pump water heater is 5°C to 55°C, and the working ambient temperature is -25°C to 45°C. The use of thermal ...

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Problems solved by technology

[0003] The purpose of the present invention is to provide an electronic expansion valve control method for a heat pump water heater, so as to solve the problem that the existing heat pump electronic throttle valve control system cannot adjust the target superheat according to the comprehensive state of the water tank temperature, ambient temperature and exhaust temperature. Technical Problems of Adjusting the Circulation Flow According to the Changing Working Conditions of the Heat Pump Water Heater

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