Geneva -Saab unveiled a tilting-head, variable-compression engine at this year's annual Motor Show here-which the car maker claims delivers 30% better fuel economy with peak power comparable to a conventional engine having twice the displacement. Key to the Saab Variable Compression (SVC) engine is a cylinder head with integral cylinders (the monohead) which is pivoted at the crankcase relative to the lower portion, made up of the engine block, crankshaft, and pistons. The five-cylinder, 1.6(liter) displacement engine, a prototype and not a production configuration, produces 225 hp and 224 lb-ft of torque.
The tilting mechanism in the Saab Variable
Compression engine changes the slope of the upper 'monohead' by up to 4
degrees relative to the engine base, which increases combustion chamber
volume, lowering the compression ratio at high
Compression ratio is de-creased for high load conditions (i.e. acceleration)
by a hydraulic actuator that tilts the monohead up to 4°relative to the
crankcase. This increases combustion chamber volume, lowering the compression
ratio to avoid fuel pre-ignition (knocking). A rubber bellows seals the monohead
to the crankcase. Taking into account the engine speed, load, and fuel type, the
engine management system continuously varies the compression ratio between 14
and 8:1. Other vital features include using a basically small displacement
engine (with low pumping losses) and a mechanical supercharger. Saab engineers
chose to forgo their trademark exhaust-driven turbocharger in favor of a
mechanical compressor because of the quick response needed by the SVC engine
along with double the boost pressure (2.8 bar or 40 psi) compared to their
current production engines.
Producing high-quality end-production metal parts with additive manufacturing for applications like aerospace and medical requires very tightly controlled processes and materials. New standards and guidelines for machines and processes, materials, and printed parts are underway from bodies such as ASTM International.
Engineers at the University of San Diego’s Jacobs School of Engineering have designed biobatteries on commercial tattoo paper, with an anode and cathode screen-printed on and modified to harvest energy from lactate in a person’s sweat.
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