This paper presents the analysis and design of a variable compression-ratio and displacement engine concept - the Alvar Cycle using a four-stroke engine-performance simulation. The Alvar-Cycle engine uses secondary pistons which reciprocate in auxiliary chambers housed in the cylinder head, at adjustable phase-angle differences from the primary pistons. The phase difference provides both the variable total engine displacement and compression ratio. Results indicate that the Alvar engine can operate at higher power density via a combination of higher intake boost and lower compression ratio to avoid knock at high loads, and capture the better thermal efficiency at higher compression ratios at part loads.
Increased Power Density via Variable Compression/Displacement And Turbocharging Using The Alvar-Cycle Engine
Sae Technical Papers
International Congress & Exposition ; 1998
23.02.1998
Aufsatz (Konferenz)
Englisch
The "Alvar" Engine Concept: A variable compression ratio spark ignition engine
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