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
There's no money in it.

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.



Please log in.
Before you can vote, you need to register. Please log in or create an account.

Duocylinder Supercombustion II

Vapor Ignition
  [vote for,

Alright let's try this again... again, the first two had their flaws.

This idea combines the Scuderi Cycle, Crower Cycle, and Miller Cycle to hopefully create a very efficient engine. The concept behind this is using waste heat to boil a liquid fuel so that when it comes into contact with oxygen it will combust.

The Scuderi Cycle works by having two cylinders for different strokes. The first one sucks in and compresses the air, the second one combusts it. The compression cylinder can be larger than the combustion cylinder for a supercharging effect (more air into a smaller space), and is always a few degrees behind the combustion cylinder so that it can fire after TDC. But my idea uses this cycle differently.

Picture a 3L flat-6. The 3000ccs is the measure of the combustion cylinders. Instead of just having a combustion, exhaust cycle, it goes combustion, exhaust, fuel injection/expansion, compression (with the fuel injection and expansion very similar to the Crower Cycle). Now picture a 1.5L flat-6 (half the displacement) on top of the 3L one, driven by gears so that it rotates at 1/2 the speed of the 3L. When warmed up, the combustion cylinders at the bottom go through their combustion, exhaust, fuel expansion, compression cycle like normal. A few degrees after the fuel is compressed after expansion, the crossover valves open and the air from the compression cylinders is forced in. Once the air hits the boiled fuel it combusts. Now the reason the compressor cylinders are rotating half the speed of the combustion ones is that the combustion ones go through twice the cycles, so to compensate the compression ones must rotate half the speed (otherwise they would go through two compression cycles for only 1 required from the combustion cylinders).

The reason the compression cylinders are smaller than the combustion ones is so that when the air hits the boiled fuel, combustion won't overpower them (F.R.O.G. if you're reading this, know that I took your advice from the first version of this). But this is also awefully convenient, since it means that a supercharger can compensate for their smaller size by forcing in twice the air. And what's more, they will do it more efficiently than the pistons could anyways. And on top of that, at low RPMS valve timing allows the Miller Cycle to occur so that even more efficiency is squeezed out.

So now picture the roots-type supercharger above all the cylinders, belt driven from the combustion cylinders. Only the belt is connected to a CVT to control exactly how much boost is given to the compression cylinders. The reason for this is that the combustion cylinders are connected to two very large turbochargers (with variable vane technology to prevent excessive backpressure) that eventually take over for the supercharger at high RPMs, and allow the engine to work much less hard (since they're using some waste energy from the exhaust rather than energy sapped directly from the engine, and centrifugal pumps are more efficient at high RPMs anyways). The CVT factors in the data on the pressure created by the turbochargers and subtracts that from the pressure needed to create a ratio so that the supercharger makes up the difference. At low RPMs the difference would be almost 100%, at high RPMs the difference would be close to 0%, but there's still always that middle ground.

Now the benefit to all of this is that this engine would burn very cleanly and could use ANY liquid fuel. You want to fill up with ethanol, go for it. You happen to be low on fuel and near a gas station that only has gasoline, fill 'er up. You have some left over heating oil, hey why not? The reason is because the heat from the pistons is enough to boil any liquid. And once in its gasseous state, any liquid fuel will combust when in contact with compressed air. And besides that, it will do so extremely efficiently. Picture using biodiesel (vegetable oil) as a fuel, a fuel made simply by pressing on vegetables. Never mind extremely high required compression ratios or bulky and oversized parts that make a very slow revving and boring motor, if used in this engine it could be light and high revving. Not to mention the fact that it wouldn't smell nearly as bad from partial incomplete combustion, because when boiled, fuels are as atomized and ready to combust as ever.

acurafan07, Sep 23 2007

Scuderi Cycle http://www.scuderig...the_technology.html
How it works [acurafan07, Sep 23 2007]

Crower Cycle http://en.wikipedia...i/Crower_six_stroke
How it works [acurafan07, Sep 23 2007]

Miller Cycle http://en.wikipedia.org/wiki/Miller_cycle
How it works [acurafan07, Sep 23 2007]

CVT Supercharger Drive CVT_20supercharger_20drive
Where I got it from [acurafan07, Sep 23 2007]

two stage turbo? http://www.theautoc...6/09/28/023361.html
[the dog's breakfast, Sep 24 2007]

vapour lock....... http://en.wikipedia.org/wiki/Vapour_lock
[the dog's breakfast, Sep 29 2007]


       I'll have to think this one over. Be back later tonight...
F_R_O_G, Sep 23 2007

       Not sure on it yet. Initial reaction is 'less bits is best'. I can see what you are trying to do with two boosting systems, but seems over done - more gear running is more mass to accelerate - less efficiency. What about just a two stage turbo or a centrifugal supercharger instead of roots?
the dog's breakfast, Sep 24 2007

       Sure, a two stage turbo or centrifugal would probably work better.
acurafan07, Sep 24 2007

       It gets better. But effectiveness of your design is still in question for me. I don't think you would have to have the cylinders smaller and have the cycle at half speed. You could just have it half speed like before. I now realizes that it could be possible to have your first "duocylinder supercombustion" work, but with your first design only half of the force would be harnessed because half of the force or the engine would be used to drive the compression piston. If you have a smaller compression cylinder that ofcorce means less air and when you add the twin turbos you add a lot to the price and where the power comes in and you make it unlikely to have this engine in a grocery getter. Yes it would work but I think there may be a better way to do this... (read on)   

       Your trying to do two things here at once in a engine that does not need to be this complicated. By you separating the air and the gas you can then create an engine to harness the force of the gas expanding but at what expense? you now have more valves and turbos and an entire new driveshaft, rods, and pistons to deal with. you can get the same results with a high compression engine by injecting gas into a combustion chamber at the time of combustion. This would work just as well. The heat would make the gasoline into gas putting pressure on the piston then ignite the gaseous gasoline almost as fast as you can inject it. This would have the benefits of your engine without all the turbos and extra cylinders working against the engine.
F_R_O_G, Sep 26 2007

       Hmm, well the smaller the pistons for compression, the easier they are to turn. It's not the power from expansion I want to harness, it's the cleaner burning of boiled fuel. And I doubt it would actually boil if you injected it into an engine that already has air in it (like you suggest), which is the reason why I separate them.
acurafan07, Sep 26 2007

       Gasoline in it's liquid form doesn't burn, only it's vapor burns. Sorry your goal has already been achieved in every single engine...
F_R_O_G, Sep 27 2007

       Just because it is atomized doesn't make it boiled. If what you said was true, no engine could ever start if the engine was below the boiling temperature of gasoline.   

       An analogy: buy a water battle and twist the nozzle so that the water comes out in a fine mist. Is this water now steam? No. Could boiling it make the mist finer? You can bet on it.   

       I believe this would be especially useful for biodiesel, since it is pretty hard to atomize it and have it burn cleanly in normal engines.
acurafan07, Sep 27 2007

       A property of gasoline is that in a liquid form the gasoline will not burn only in a vapor form will it burn. Look it up if you don't believe me.   

       This is the way I see a cold engine starting. The way that an engine can start while cold is the heat from the spark causes some of the atomised gas to vaporise and burn causing more heat causing more atomised gas to vaporise and burn.   

       Now I can still see that it would be help power the engine by vaporising the gas inside the cylinder and you would be able to have very high compression but I see a much easier way of doing it.
F_R_O_G, Sep 27 2007

       And that is...?
acurafan07, Sep 27 2007

       Compression cycle provides plenty of heat to turn injected fuel mist to vapour.   

       Some vehicles (namely the boss' old F350) have problems when the fuel rail becomes too hot - fuel becomes too hot and vaporizes before injectors - engine does not run until cooled. How would you prevent this?
the dog's breakfast, Sep 28 2007

       Since the air and fuel aren't being mixed until combustion that wouldn't affect this at all.
acurafan07, Sep 28 2007

       the idea i mentioned before   

       //injecting gas into a combustion chamber at the time of combustion.// using a normal Otto cycle
F_R_O_G, Sep 28 2007

       But you aren't taking into account that the compressed air is taking up space and is absorbing heat. It might work for gasoline, but I know that diesel has to be injected at extremely high pressure.
acurafan07, Sep 28 2007

       I believe that vapour lock would affect it seeing as though you want to boil the fuel. See link.
the dog's breakfast, Sep 29 2007

       But see I want it to boil in the cylinder, not the fuel system. It would get injected and the piston's heat would boil it, not get boiled before injection.
acurafan07, Sep 29 2007

       Oh. So what you are describing then when you say 'boiled' is only what happens inside and engine as part of its normal cycle?
the dog's breakfast, Sep 29 2007

       Yup. I should have made that more clear in the idea, sorry.
acurafan07, Sep 29 2007

       the F-430 and the Scud'458 works exactly likes this, and It Flies !!!!!!!!!!! :-) s.   

       (430 coupe more mechanical, 458 a little 'rumply', but 'bigger' in traction, and possibly beyong high-way code !, s.
sirau, Jul 07 2011


back: main index

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