Valve dynamics in reciprocating compressors for motor vehicles

Pouzdanost i termodinamička svojstva stapnih kompresora uvelike ovise o ventilu. Budući da se ventili otvaraju i zatvaraju automatski, postoji intenzivno djelovanje dinamike ventila i elementa za brtvljenje na protok plina kroz ventil. Loše karakteristike ventila neminovno dovode do degradacije rada kompresora i /ili kratkog vijeka trajanja ventila. Kratki vijek trajanja ventila rezultat je prekomjernih udarnih sila između elementa za brtvljenje i drugih dijelova sklopa ventila. Usklađivanje ventila sa specifičnim stapnim kompresorom složen je zadatak koji zahtijeva primjenu odgovarajućih matematičkih modela prije nego se ventil uskladi. U ovom radu predstavljamo matematički model za predviđanje dinamike ventila. Matematički model se provjerava mjerenjima termodinamičkih karakteristika specifičnog stapnog kompresora u motornom vozilu. Zaključeno je da se matematički model dobro slaže s rezultatima laboratorijskih ispitivanja.Reliability and thermodynamic properties of reciprocating compressors are largely dependent on the valve. Since the valves open and close automatically, there is an intensive impact of the valve and the sealing element dynamics to the gas flow through the valve. Poor valve characteristics inevitably lead to degradation of compressor performance and/or short lifetime of the valve. A short lifetime of the valve is the result of excessive impact forces between the sealing element and other parts of the valve assembly. Matching the valves to the specific reciprocating compressor is a complex task that requires the use of appropriate mathematical models before the realization of the valve. The mathematical model for the prediction of the valve dynamics is presented within this paper. The mathematical model is verified by measurements of thermodynamic characteristics of the specific reciprocating compressor used in motor vehicles. It is concluded that the mathematical model agrees well with the results of laboratory tests