Abstract
Keywords: air conditioning system, R744, sealing, permeation, explosive decompression
In the future, German automobile makers are expected to use only the particularly environmentally-friendly, natural refrigerant R744 (CO2) in mobile air conditionings. Using HNBR, EPDM and PTFE-based sealing materials developed just for this purpose, the entire range of needs for all sealing functions in all three circuits of a R744 air conditioner can be covered.
These optimized sealing materials are characterized by permeation rates of 0.5g per year and connector. They can be used under pressures up to 140 bar and in a temperature range from -40°C to +180°C. There is no risk of explosive decompression and the materials have an excellent oil resistance and aging resistance.
These sealing materials are precisely designed and checked in accordance with the VDA stress spectrums such that in different types of seals they provide dependable and long-term stability in both static as well as dynamic sealing contact points in modern R744 air conditioning systems. O-rings, shaft-seals, flat gaskets, face seals, miniaturized elastomer bonded components and compressor piston rings allow tested complete sealing packages to be built that meet the tightness requirements of the automobile industry.
In addition, elastomer seals offer considerable advantages with respect to the tolerance compensation, vibration compensation and the R134a technology-based assembly.