Half a croissant, on a plate, with a sign in front of it saying '50c'
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Asymmetric Cylinder Displacement Engine

  [vote for,

CDE's (Cylinder Deactivation Engines) "turn off" cylinders when power requirements are low, which saves quite a bit of energy when it's not needed.

So, for a theoretical 3cyl engine with 0.5litre pots, you could have 3 displacements and their attendant economy sweet spots: 0.5L or 1L or 1.5L.

But, if all the cylinders are different sizes, there would be up to 7 different active displacements available.

It wouldn't be the smoothest engine, but it would be overall more economical, and sound awesome, or at least "unique", with all cylinders engaged.

FlyingToaster, Apr 17 2015


       A V6 might be better as it would have intrinsic balance.   

       It certainly sounds like a novel approach to the problem.   

       A straight six with a large - medium - small - small - medium - large layout would have intrinsic balance and ease the problem of cooling the middle cylinders. Crank throws would need to be carefully chosen to ensure the different diameters were more or less "square" in terms of stroke.   

       Power delivery might be a bit lumpy. Might do better through a n automatic or hybrid transmission.
8th of 7, Apr 17 2015

       There's a problem?
normzone, Apr 17 2015

       This thing would be wretched to drive, impossible to balance, and would blow the accessory drive apart.
RayfordSteele, Apr 17 2015

       Supercharging, or not, a small engine will give the power or economy this idea addresses.
cudgel, Apr 18 2015

       [RS] the "3cylinders" is for illustration purpose; see 8ths //inline 6//, turning cylinders on/off in pairs, which is probably better balanced than a normal I-3 cylinder... though I like the idea of a 3cyl radial. as far as accessory belts are concerned, feel free to imagine a complex set of active tensioner pulleys... or a big flywheel.   

       [bs] in a CDE the //spare suck// is already completely regenerated, by closing the valves on the unused cylinders.   

       [cudgel] huh ?
FlyingToaster, Apr 18 2015

       Supercharging, or not, a small engine will give the power or economy this idea addresses. — cudgel, Apr 17 2015   

       Small engine, or not, supercharging will give the power this idea economically does not address.
normzone, Apr 18 2015

       There is a type of IC engine that doesn't have a crankshaft; its back-and-forth motion is directly converted to Alternating Current in a manner similar to an ordinary bar magnet moving back-and-forth inside a coil. Note that there could be a piston at both ends of a simple straight shaft.   

       So, if this engine had 3 pairs of such diametrically- opposite cylinders of different sizes (with appropriate electronics to convert AC for a DC drive motor), there could be less concern about dynamic balance, because no crankshaft is involved, to receive different forces at different places on the shaft.
Vernon, Apr 18 2015

       Er, er, I think the handicap is that if 2 cylinders are de-activated, then one pot is trying to move the car and compress the air in the cylinders which are having a bit of a lie-down. So, you'd have to vent pots 2 and 3 very well...or clutches between the pots...   

       Tricky but not impossible. Mildly baked in the original mini as the distributor was at the front, and when it rained you got variable ignition patterns.
not_morrison_rm, Apr 19 2015

       I had a Honda like that: cranky in the rain or after fording large puddles. Ran like a top otherwise though.   

       About pushing the other 2 cylinders, in the theoretical 3cyl: there's no guarantee that all the combinations will be useful, just that there's more to choose from. That being said, the other cylinders will be adding to the spin after TDC and the engine does have a flywheel.
FlyingToaster, Apr 19 2015

       //compress the air in the cylinders which are having a bit of a lie- down. So, you'd have to vent pots 2 and 3 very well. //   

       Valve droppers on the exhaust valves of the "dead" cylinders. Not on CVH engines, tho ...
8th of 7, Apr 19 2015


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