Scuderi split-cycle engine
American engineering firm Scuderi claims their new split-cycle engine to be among the most efficient internal combustion engine designs ever. Most combustion engines are 33% efficient, which means that they use about 1/3 of the power available in the fuel they burn. The Scuderi engine improves this figure to almost 40%.
This engine design splits the strokes of the four-stroke cycle over a pair of dedicated compression and power cylinders, meaning that the design of each cylinder can be independently optimized to perform the separate and distinct tasks of compression and power...
That means that engines can be designed in ways that were previously impossible.
Full story here.
- Permalink | Comments (5)
- Posted by: Bob Holland April 18, 2008, 6:12 AM
- Categories: Green Tech
I took a long look at their website and the explanation is pretty easy to follow. They admit the idea isn't new, but it seems they've finally overcome the engineering hurdles to make it feasible and more effecient than the traditional four stroke design.
The problem though, is that it will suffer from those three magic words, "Not Invented Here".
Small chance any of us would see this put into use on a production car anytime soon.
Estreka, according to the Scuderi website it fires every cycle because it doesn't have to deal with intake or compression. The power cylinder moves to the top position during the exhaust phase to push out the exhaust gas. When it reaches its top position, the compressed intake air from the other cylinder is injected. So instead of having a power stroke 1 out of four movements for four cylinders, you have a power stroke on 1 out of 2 movements for two cylinders. So power output from the egine would identical.
Also you could have weight savings because the intake/compression cylinders won't have to be made to handle the same type of abuse that the combustion/exhaust cylinders would. They could conversely be made more durably with a mind toward longer engine life.
Yes, its true that you'll have two cylinders receiving more wear, but with modern machining capabilities you still shouldn't have to worry about that until you've got at least 200K miles on the car.
Also on the company's website they talk about this allowing for better configuration of the engine to reduce friction and wear.
I really get intrigued by engineering solutions and ideas. Its an interesting idea and I'd like to see it applied in a test car. As far as I could tell, the website was basing their findings off of computer simulations.
Contrary, I count an additional step.
1. The combustion cycle forces the piston down.
2. The piston then goes back up, forcing the exhaust out.
3. Either the cylinder would have to stay in the up position while compressed fuel is injected (after the exhaust valve(s) close) or the cylinder would descend again, drawing in fuel, which is a simple 4-cycle.
If the piston stays up, then you have to have an advanced crankshaft (maybe lobed like a camshaft?), a hardworking air pump (or piston as stated), and a myriad of complex headworks (cams, valves, computer, etc).
I could see a potential weight savings if the compression pumps (or pistons) were feeding more than one power cylinder. Imagine 2 big pistons feeding 8 power cylinders.
I still disagree about longevity. You have pistons doing twice the work. Yes you'd only have to change out half the pistons during an overhaul, but you'd need an overhaul twice as often. I can only imagine the oil consumption.
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I love engineering solutions too, but I'm not convinced this is feasible.
Now that I think about it, though, this might be quite effective in a diesel application.
AUTHOR: estreka
DATE: 04/18/2008 05:31:34 PM
EMAIL: estreka@yahoo.com
The concept is interesting but from what I read it sounds more at the theroy stage then the production stage.
Since they are just preparing prototypes now, they have a long way to go to prove the design does what they claim and will last in the real world.