Abstract: As one of the core components of the air conditioning system, the expansion valve is used to regulate the refrigerant flow rate, reduce the refrigerant pressure, and meet the requirements of the air conditioning system when the load changes. However, traditional thermal expansion valves have problems such as low adjustment accuracy and poor adaptability. In order to overcome these shortcomings, electronic expansion valves have emerged. However, electronic expansion valves also have their own shortcomings. For example, under high pressure differential conditions of refrigeration and heating, the electronic expansion valve may experience out of step problems, which not only affects the performance and energy efficiency of the unit, but may even lead to excessive system pressure and damage to the compressor. To solve this problem, experimental analysis was conducted and corresponding optimization measures were proposed. The results indicate that under high pressure differential conditions, the forward flow of refrigerant is beneficial for improving the control accuracy of electronic expansion valves; Strengthening the stiffness of the electronic expansion valve spring can improve the response speed and flow control accuracy of the valve, and reduce the probability of valve out of step. This study has certain reference value for solving the problem of electronic expansion valve out of step in air conditioning systems.

Key words: Air conditioning system, Electronic expansion valve, Heating machine, Valve out of step