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    Mazda May Have Given The Rotary Engine A New Lease On Life


    William Maley

    Editor/Reporter - CheersandGears.com

    March 19, 2012

    Mazda is the only automaker to stick with the rotary engine; spending a considerable amount of time and money in order to improve efficiency and reliability of the engine.

    Despite saying goodbye to their only rotary-powered vehicle (the RX-8) and no word if there will be a successor, Mazda has made a breakthrough.

    Mitsuo Hitomi, Mazda’s general manager of powertrain development told Ward’s Auto that the company will complete development of an all-new rotary engine that meets future fuel-economy and emissions standards.

    “We think we’ve found a way to improve the rotary’s fuel economy to be truly equal to that of conventional piston engines and, if so, we believe we can reintroduce the rotary to the market.”

    Those improvements Hitomi is talking about include changing the shape of the rotor housing to improve sealing, and designing a new intake manifold to reduce engine displacement. Both are said to improve improve gas mileage and lower CO2 emissions.

    Hitomi also said the company tinkered with the engine’s ignition. He didn’t go into any details, but promised the end result will be “dramatic improvements” in both fuel consumption and ignitability.

    This information is sure to make rotary fans very happy about a new RX vehicle, but Hitomi

    sees another use for it; a range-extender in an electric vehicle.

    When asked when the Rotary with all of these improvements will be seen, Hitomi wouldn’t confirm a date.

    Source: Ward’s Auto

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    I wonder if I am the only one who feels this way. Who Cares, the rotary still does not show any potential to replace with outstanding technology, fuel consumption or any other compelling reason to bother building it. A very expensive, cool engineering product but no real future. This is a waste of money and goes to explain why Mazda is bleeding cash. Poor mgmt decisions on where to invest resources.

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    The advantage of the rotary engine is that there are three power impulses for every rotation of the full rotor vs 1/2 a power impulse for each rotation of the crankshaft in a 4-stroke piston engine. This gives it a very good power density -- output per unit engine (exterior) dimension and/or engine weight.

    The problem with rotaries is not that it is complicated or technically challenging. It is actually not -- on both counts. The problem with the rotary is fundamentally two things... (1) The engine compresses the charge, ignites and expands it in different locations in the engine. This means that the heat from the combustion has to be removed completely by the cooling system and cannot transfered to the intake charge. This leads to poor emissions (it's like a piston engine's condition right after a cold start, except its in perpetuality), and it leads to reduced thermal efficiency (less thermal energy recovered to the next charge rather than dissipated in the cooling system). (2) The apex seals of a rotary never normally traverse an area covered in oil -- unlike the piston rings in a piston engine -- hence oil must be injected with the intake charge to lubricate them or they'll run dry forever. This slightly in creases hydrocarbon emissions, but more importantly it causes the inconvenience of rotary having to burn a significant amount of engine oil by design.

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    I think the Wenkel Rotary makes sense as a range extender engine especially if they can really match the efficiency of the reciprocating engine for two reasons; In a hybrid the smaller size engine is perfect because it will save on space and weight, In addition the engine will be smoother cutting down on the vibration and noise produced by a piston engine.

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    Thanks Guy's, those are interesting points to consider, but I think the enviornmental issues outweight the small size/power. Interesting to consider still.

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    As a range extender, if the lack of vibrations and high power density are paramount, I'll very much advocate for the use of a gas-turbine generator.

    A single spool turbine only has one moving part. A dual spool unit only has two. IT can be spun up to starting speeds by the motor-generator it is supposed to drive. It is perfectly balanced and has no vibrations. It'll reach the high-20s to low-30s in thermal efficiency at its optimal operating speed which is roughly the same as a run of the mill gasoline piston engine at cruising speed (where it is least rather inefficieny from being choked by the throttle body). It'll make 40~50 hp from a turbine assembly roughly the size of a 100 pcs stack of CDs. It doesn't need a radiator or coolant loop. It'll run on diesel or gasoline or kerosene at the flick of a switch.

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    As a range extender, if the lack of vibrations and high power density are paramount, I'll very much advocate for the use of a gas-turbine generator.

    A single spool turbine only has one moving part. A dual spool unit only has two. IT can be spun up to starting speeds by the motor-generator it is supposed to drive. It is perfectly balanced and has no vibrations. It'll reach the high-20s to low-30s in thermal efficiency at its optimal operating speed which is roughly the same as a run of the mill gasoline piston engine at cruising speed (where it is least rather inefficieny from being choked by the throttle body). It'll make 40~50 hp from a turbine assembly roughly the size of a 100 pcs stack of CDs. It doesn't need a radiator or coolant loop. It'll run on diesel or gasoline or kerosene at the flick of a switch.

    Turbines are cool and I wish more cars would consider using them as an engine source.

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