Expansion valve, and refrigeration cycle system using expansion valve

摘要

Provided is an expansion valve, including: a case having a valve chamber formed therein; and a valve element arranged in the valve chamber. The case includes: a side wall portion to which a first pipe is connected; and an end wall portion to which a second pipe is connected. The end wall portion has a fluid communication hole to be opened and closed by the valve element. The fluid communication hole is formed so that the following expression is satisfied: Lλ/2, where L represents an axial length of the fluid communication hole, and λ represents a resonance wavelength.