Half a croissant, on a plate, with a sign in front of it saying '50c'
h a l f b a k e r y
Expensive, difficult, slightly dangerous, not particularly effective... I'm on a roll.

idea: add, search, annotate, link, view, overview, recent, by name, random

meta: news, help, about, links, report a problem

account: browse anonymously, or get an account and write.



3-Stroke Engine

Diesel 2-stroke with Miller-cycle-like modification
  [vote for,

Take a diesel 2-stroke, with intake ports at the bottoms of the cylinders and exhaust valves at the top, add passages from the exhaust valves to another cylinder (also valved for reasons that will become obvious). Second bank of cylinders have valves coming from first bank and a second set of valves going to exhaust. The two cylinder banks are synchronized by gears, or whatever else, so that each cylinder in one bank moves in sequence the same cylinder in the other bank.

A supercharger pushes air into cylinder at BDC, piston compresses air, diesel is injected, and *bang*, just like any other diesel 2-stroke.

Here's where it's different -- exhaust valve opens to other cylinder immediately, allowing twice as much (or whatever, depending on second cylinder's size) expansion for higher efficiency. Leave exhaust ports open long enough to evacuate cylinder #1 and close again. While fresh air is compressing in cylinder #1, secondary exhaust valve in cylinder #2 is opened, pushing remaining gasses out to the atmosphere. Close those right before *bang* in first cylinder and repeat...

Anyway, you might make the secondary expansion cylinders a little smaller. This kind of applies the ideas of Miller and Atkinson to two-stroke engines. I think it would be more efficient than a four-stroke (and probably better power to weight ratio), but I don't know how it would stack up against a Miller-cycle four-stroke.

65Stang, Jan 28 2004

Constant Volume Combustion http://www.ducati.c...rt=general&artID=11
Ducati Tech Cafe artice about Italian engine design. http://www.ducati.com/bikes/techcafe.jhtml?detail=article&value=theory&part=general&artID=11 [discontinuuity, Jun 01 2005]

http://www.scania.c...ania_turbocompound/ this is another way to scrape a few more ergs out of your exhaust stream [elhigh, Jun 13 2005]


       Sort of like some model airplane engines I have seen featuring a secondary expansion chamber.   

       I don't think that the power gain from the extra expansion cylinder would outweigh the diffrence of just having another normal cylinder. And im willing to bet the power to weight ratio wouldn't be much better too.   

       But its creative, so it gets my vote.
KLRico, Jan 28 2004

       Since travel in each direction is considered a stroke, you can have either a 2-stroke or a 4-stroke. (A steam engine would be considered a 1-stroke) What I see is basically a method for increasing the effective area of the piston during the power stroke. There are steam engines and some small gas engines that use secondary (and sometimes even tertiary) expansion chambers that work to extract wasted energy from non-fully-expanded exhaust gases, so in that aspect, this is baked.
Freefall, Jan 28 2004

       Steam can have two-strokes, expansion and exhaust, and many are "double-acting" in that they have steam coming in from both sides of the piston alternately.   

       Double- and triple-expansion steam engines blow the exhaust from one cylinder into another, larger cylinder taking every last bit of energy out. I did see someone show a design for this in a gasoline engine and that got me going into this idea.   

       The reason I called it 3-stroke is that while the first cylinder is on a compression stroke, the second is actually performing an exhaust stroke, which doesn't exist in a 2-stroke. However, there is no intake stroke, as a 4-stroke begins on -- the supercharger pushes an intake charge into the cylinder.
65Stang, Jan 29 2004

       Guy Negré of Carroz, South of France, inspired FIAT to deliver the Multi Air, tech, to market, by this sort of Tandem thinking, in a 'ZERO-POLLUTION.com' production.   

       The Negré project, had something like 300 bars/atms fiber tanks, and this type Tandem-connected cillinders ' of Work and Pressure, distributed in cross drilling channels.   

       'Might be a tech release coinsidence',, but the cross drillings are the same. In the Multi Air, though, in the Camshaft section, controlling through flow, and air deliveryies',, like 'turbo' blasting off', no throttle !!!!!!!!!,. !!,.   


sirau, Jul 07 2011


back: main index

business  computer  culture  fashion  food  halfbakery  home  other  product  public  science  sport  vehicle