Comparison of load response of SI engines that use various supercharging methods

Prednabijanje usisanog zraka u motorima s unutarnjim izgaranjem nudi niz pogodnosti od kojih je jedna povišeni efektivni moment kroz cijeli raspon brzine vrtnje motora. U ovom radu opisani su načini rada i osnovne značajke raznih uređaja za prednabijanje, s posebnim naglaskom na turbopunjač i mehanički pogonjeni kompresor. U programskom paketu AVL Boost izrađena su tri modela temeljena na odabranom Ottovom motoru, gdje je prvi opremljen mehaničkim kompresorom, drugi turbopunjačem fiksne geometrije, a treći turbopunjačem potpomognutim elektromotorom. Predstavljene su dvije strategije upravljanja radom elektromotora, od kojih se u jednoj koristi mogućnost regenerativnog kočenja pri višim brzinama vrtnje u svrhu generiranja električne energije. Napravljena je priprema za provođenje tranzijentnih simulacija, koja uključuje definiranje radnih točaka početnog i krajnjeg opterećenja te određivanje potrebnih položaja zaklopke za snagu. Naglim promjenama položaja zaklopke, na temelju odziva efektivnog momenta, prosuđivalo se o prednostima i manama pojedinog uređaja. Brzine vrtnje pri kojima se vršila usporedba su 1400 i 2400 min-1, te su na temelju istih izneseni zaključci.Charging of internal combustion engines offers a number of benefits, one of which is an increased effective torque across the entire engine speed range. Operating principles and basic features of the various supercharger devices, primarily focusing on the turbocharger and the mechanically driven compressor, are presented in this paper. In the AVL Boost software, three engine models that are based on the selected spark-ignited gasoline engine are defined, where the first one is equipped with a mechanical compressor, the second one with a turbocharger with fixed geometry and the third one with electrically assisted turbocharger. Two strategies for the operation of electric motor have been presented. In one of the strategies the possibility of regenerative braking at higher engine speed with a purpose of generating electricity is considered. In the paper the preparation to perform transient simulations is made, which includes defining the starting and ending operating points and determination of the required throttle positions. Due to the sudden changes of the throttle position, on the basis of an effective torque response, the advantages and disadvantages of individual supercharging devices are assessed. The conclusions were derived from the comparisons at 1400 and 2400 rpm