The math on that problem is pretty simple: one big piston (ala Steam engine size) has less side load friction than a bunch of smaller pistons because it has less side load area.
Posted on 02/21/2002 1:31:00 PM PST by John Jamieson
Hi Efficiency Engine Design
John Jamieson MIT67
I’ve been studying the reasons that modern internal combustion engines operate at 25 to 30% efficiency for the last year or so. There are basically three main areas that seem repairable but would lead to large efficiency increases.
1. Current engines are symmetrical stroke. They have the same compression ratio as exhaust ratio. About 10 to 1 is the limit for compression ratio with modern gasolines, but the ideal expansion ratio is more like 25 to 1. Atkinson realized this problem in 1896 and patented and built many engines to prove the concept. He was run over by lighter, smaller, cheaper Otto cycle engines. (Current “Atkinson cycle” engines are really “Miller cycle” engines, without asymmetrical strokes).
2. Current engines cannot adapt to variable displacement to adjust output. High output can very efficient but low output requires throttling of the air, reducing compression ratio and efficiency. (Most cars only require 10 to 20 horsepower to cruise at 60 mph).
3. Current engines generate about half their internal friction due to piston side loads. Several patents claim to correct this but most are statically indeterminate, which means they don’t work.
Come up with a new engine design that fixes these three problems and you’ll improve IC engine efficiency by 50 to 100%.
Please don’t tell me about any existing technology, I’m familiar with the vast majority of existing designs, having studied over a thousand patents. Most don’t close to solving these three problems in any practical way. Original ideas only please. Yes, I do have a design that solves two of the three problems, that I’d be glad to share with anyone interested. (Graphical simulation in VB available).
You forget the necessary heat loss. Develope a lubricant that will withstand 400 deg F and you can greatly increase efficiency.
Have you considered variable valve timing and radical cam design in conjunction with high compression?
I think this represents public disclosure of your invention, and does have ramifications in regards to patent law.
Some type of bypass port in the cylinder wall that opens on compression stroke but closes on the power stroke, perhaps?
What do you mean when you say "efficiency"? How are you defining it?
Hey, you asked for original ideas. You didn't say they had to be good ideas.
Then there is always the good old fashioned Tesla turbine. Has that ever been developed into a useful product?
The math on that problem is pretty simple: one big piston (ala Steam engine size) has less side load friction than a bunch of smaller pistons because it has less side load area.
OTOH, with electronic or computer-controlled valves, you could drop a few cylinders on the engine to zero compression, limiting engine displacement to only what's needed (problem 2).
Like the old Cadillac V8-6-4 engine, except make it work RIGHT this time...
Maybe you should take a look at the total system -
- and look to recover some of the kinetic energy the vehicle has when coming to a stop (where, normally, all THAT energy is simply turned to heat in the brakes).
Oh, sorry - Toyota and Honda beat you to it!
(To wit, the Prius and the Insight.)
Do the "Turbo Compound" thing, like on the Lockheed Constellation airplane. Uses a turbine in the exaust to capture wasted energy and directly powers the drive shaft. This uses up the wasted expansion ratio.
I'm familiar enough with patents that I can say that even though this has been done, there are still zillions of opportunities to patent little necessary pieces of such things that adapt such technology to cars.
Several differential crankshaft designs using opposed pistons have been tried with limited success. Many old patents.
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