After a brief analysis of the basic load-control concepts for Otto-cycle engines used in mass-production an alternative approach is presented in order to optimize the supercharger's power consumption and control the mass flow beeing delivered. A combined supercharger-expander could work as a throttle loss recovery device for Otto-cycle engines at partial load. The presented control-concept for twin-screw-superchargers using rotary-valves to control mass-flow and minimize effective shaft power for a given pressure ratio could be verified regarding usefulness and basic feasibility. Key factors in this concept are the minimization of clearance-flows and mechanical losses. Because of the specific requirements regarding clearance distribution, high precision of the synchronizing gears and integration of the rotary-valves into a compact, automotive-standard component it seems necessary to design a completely new purpose-built unit to make best use of the potential advantages of the concept. Another potential problem is the forces involved in adjusting the rotary-valves at very low pressure ratios, when they are sucked onto their seats because of the pressure-differential. This could be solved by using dedicated low-friction bearings for the turn-valves without sacrificing small clearances, compromising the simplicity of the prototype's design. If it is possible o overcome the design-challenges the concept might provide advantages over the current methods of load control used for petrol engines with twin-screw superchargers for diesel engines, aimed at reducing the supercharger's power-consumption at part-load conditions by allowing better adaption of the internal compression to the required pressure ratio.
Control concepts for an integrated twin-screw supercharger and throttle-loss power recovery device for Otto-cycle engines
Steuerungskonzepte für einen integrierten Zwillingsschraubenlader mit Drosselverlustrückgewinn für Ottomotoren
2001
11 Seiten, 8 Bilder, 4 Quellen
Aufsatz (Konferenz)
Englisch
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