Abstract: The mechanism of large displacement scroll compressor injection pressure fluctuation was analyzed due to a market failure of injection hole impurity invasion, which was actually as result of the valve element breakage of a VRF enhanced vapor injection valve. Various injection hole positons and structures were also studied, in order to clarify their influence on the injection pressure fluctuation. The results show that the injection pressure fluctuation is mainly determined by the pressure difference of the upstream and downstream of the injection hole and local pressure variation. By adjusting the injection hole positon to the suction side and applying multiple hole or stepped hole structures, the scroll compressor injection pressure fluctuation can be effectively improved, which helps to enhance the reliability of the VRF system.

Key words: Scroll compressor, Pressure fluctuation, Injection hole, Reliability