Wear-Less Technology for Rotary Compressor Using CO2 Refrigerant

We have developed a new CO2 heat pump water heater compressor with a single rotary mechanism in practical use for the first time in the world. CO2 refrigerant doesn't destroy the ozone layer, and the global warming potential (GWP) is less than 1/1000 in comparison to hydro-fluorocarbon refrigerants. However the operating pressure of CO2 refrigerant is approximately three times as high as that of R410A refrigerant. Therefore, it is important to secure the reliability of sliding portions under high operating pressure conditions. The single rotary mechanism is used in mainstream R410A refrigerant air conditioning systems. However, CO2 refrigerant has not been used practically for CO2 refrigerant systems due to the difficult issue of securing the durability against vane wear. We worked on this issue of reliability for the sliding portion between the vane tip and the periphery of the rolling piston, by applying a coating DLC-Si to the vane. As a result, even after a long duration, the DLC-Si coated vane is hardly worn-out, only the surface roughness is smoothed. We were able to achieve an excellent level of wear durability, which we call “WEAR-LESS”.