h a l f b a k e r y
Professional croissant on closed course. Do not attempt.
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This is an elaboration of [acurafan07]'s idea, "Two Stroke Diesel Miller Cycle" (q.v.), which got me to thinking about sleeve valves to time the scavenge phase. So, how about dispensing with poppet valves altogether, and using single sleeve valves with two sets of ports? The intake ports would be near
the bottom of the stroke, as on a Detroit Diesel, and the exhaust ports near the top. Intake and exhaust timing is then controlled by the same relatively simple mechanism.
Apart from relative simplicity, huge port areas are possible, with substantial scavenge cooling, which would keep exhaust temperatures within the region of sanity.
Moreover, the absence of overhead valve gear allows a considerable saving in the height of the engine. The nicest diesels are the Edwardianesque sort, that is, big, simple, slow-revving, durable, field-reparable, surprisingly light for their size, and extremely efficient. Those characteristics also render them physically bulky, and anything that allows them to be made more compact is to be welcomed.
[acurafan07]'s idea:
Two_20Stroke_20Diesel_20Miller_20Cycle
[Ned_Ludd, Aug 23 2007]
[link]
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