I promised to share my patented Engine idea with you guys, so here it is. The patent is rather large, but like eating an elephant, take little bites and you ought to 'get it.' This idea has been in my head for about 24 years, by the way. I'd really like to hear any and all comments, good or bad.

The best way to view patents, that I've found, is to use this link:

http://www.pat2pdf.org/

It puts the entire patent in a .pdf format. Even the US Patent and Trademark Office link requires you to have some software to view the images, so I've gotten away from using it. Anyway, go to that site and enter whatever patent number you'd like to see. In my case, that number is:

7185557, which is titled, "Epitrochoidal Crankshaft Mechanism and Method".

I've got a few pictures of prototype number 1, which was based on a Homelite weedeater displacing 25cc, but I need to size them down in order to post them. I went and talked to a professor at Louisiana State University in Baton Rouge, LA about it. The guy taught the Internal Combustion Engine classes over there, and we got along great. He confirmed my numbers were correct and agreed that my Engine should make 15% more power, which is exactly what I had predicted. That was a 2-stroke Engine, and I maintained the same time-area values as the original Engine contained. I did modify the ports, but only to keep the port timings in-line with the stock Engine. The important thing to consider is that the stock port values were not optimized for use with my crankshaft, so instead of a 15% increase, the potential is there for an even greater increase. In the case of the second prototype, which is based on a Briggs and Stratton 10 HP Engine, my calculations show that I could get a 28% increase in power across the entire RPM range. This is while using their camshaft, which is again not optimized for my piston position and velocity profiles.

The only drawback, and I really don't consider it as such except in extreme RPM situations, is that for a given Engine stroke, my design's piston speed will be greater than a conventional Engine's piston, provided the stroke length and Engine RPM is the same. The simple way around that is to increase the bore size and shorten the stroke to maintain the same Engine displacement. But, that increased piston speed also helps provide a strong suction pulse on the intake stroke in both 2- and 4-stroke engines, which helps increase efficiency. Also, you don't have to rev my design to the same Engine speed if you want a certain amount of power - it produces the same power as a conventional Engine at a lower Engine speed, which also increases longevity and reduces friction.

Anyway, I'd love to hear everyone's comments. I'm now patented in the US, and I have patents pending world-wide now.

Cheers,

Mark

What is the effect on emissions and fuel economy using your modifications?

Interesting idea, I haven't taken the time to fully appreciate the system, but if it works. My question would be, that's a lot more moving parts on one of the engines most beat on areas. I mean there is more power and force excerted on the crank than really anywhere else so, especially as HP increases, how well does it wear, how prone to breakage is it?

It appears this is something you are retrofitting on existing engines, anything you have to watch out for specifically?

Smash

Well, you can look at it in either an economy or power aspect if you're talking about keeping the same displacement. Our old Buddy Martin S. has done the calculations for the Briggs Engine and reports an expected increase in efficiency by 12% using the existing camshaft timing. On the Briggs Engine (and for that matter, any 4-stroke application), the camshaft is going to have to be modified to prevent taking in more air/fuel mixture than normal, since the piston is still relatively low in the cylinder when the intake valve closes and true compression begins. Right away, if nothing else changes, your trapped compression ratio is going to be much higher than it was originally - you're packing a greater amount of mixture into the same combustion space. As Martin once said, 'It's self-supercharging.' So, if you wanted to have the same fuel amount, you have to close the intake valve later to get the original sized fuel charge. Assuming you've done that, then each power stroke will start with the same amount of cylinder pressure. In the conventional Engine, the exhaust valve must open when the crank has rotated around 100 to 120 degrees so that it will be fully open when the piston turns the corner and starts back up. On the Briggs Engine, that amounts to about 83% of the total piston travel before the cylinder pressure is released. With my crank in there, the piston travels 97% of its total stroke before the exhaust valve opens (with the stock camshaft), but with the dwell at the bottom, the valve has plenty of time to open before the piston starts back up. Also, because I've 'over-expanded' the cylinder pressure, there is less cylinder pressure when the exhaust valve opens, so the exhaust note won't be nearly as loud. Anyway, it boils down to getting more work out of the cylinder for the same amount of fuel, so that's where the efficiency and economy comes in. In the case of 2-strokes, the same logic applies - the exhaust port can be lowered, which allows you to push the piston further down the bore with the available cylinder pressure, but with the piston dwell, you can still scavenge the cylinder nicely.

On emissions, I'm not that well versed, but I know that the piston will move away from TDC (Top Dead Center) quicker than normally. That tells me that the combustion gases will be cooling quicker than normal, and I've always been under the impression that the retained heat of combustion is what causes the NOx problems. Besides, if you only need a certain amount of power (such as in automotive applications), you don't care about the displacement - you only need X-amount of power. My crank should allow you to have a smaller displacement Engine, which would use less fuel to make the needed power, so emissions would have to be lower - you're burning less fuel to make that power.

Does anyone here have a degree in Chemistry, or a better explanation on the formation of pollutants? I'd like to know myself!

Hey Smash, you must have been posting as I was typing. Yes, there is more mechanical complexity than a simple piston, conrod, and crank going on in there. As far as wear goes, in my next prototype, I've lengthened the connecting rod so that the increased leverage I get with my crank doesn't cause excessive conrod angle, relative to the centerline of the cylinder. That means that the piston won't have as much of a side load against the cylinder walls. On the actual mechanism, everything is composed of rolling elements (nothing is sliding). Concerning the gear teeth wear, I don't really worry about that either - the gears are bathed in oil constantly, and the actual amount of loading they have to put up with is minimal. Even if you look at the tremendous force that gets transmitted along the length of the conrod, the amount of torque that the gear teeth see is only the product of the force times the moment arm. In the case of the Briggs Engine, that amount of moment arm only amounts to about a quarter of an inch or less. The gears are really only there to be positioning elements. All of the force still goes through the crankpin.

As far as retrofitting the crank into an existing crankcase, I think that's going to be difficult - there generally isn't going to be enough room to fit everything inside there. But, something I'd like to try is to take a crankcase from a larger Engine and fit my crank in there, but instead of the original stroke length, my crank would have a shorter stroke. If you were to start with something like a CR500, it would reduce the Engine displacement to around a 350 cc (I'm just pulling these numbers out of the air, by the way.) You would start with something bigger and build a smaller Engine out of it if you wanted to use existing components. The nice thing about doing something like that is that the transmission could still be used. Plus, if I were going to build a 350 cc Engine from scratch, I would have an over-square design to keep the piston speed in a range that prevents it from hurting itself.

What would happen if you threw in the V V C H idea too http://pilotodyssey.com/PO/viewtopic.php?t=3112
you think their would be and gains ?

Not a chemist or anything, but pollutants are mostly unburnt gas. That's why catalytic converters were put on cars, to heat up and help burn off any gas that made it past the exhaust stroke.

In what you said, you move away from TDC (Top Dead Center) faster, but to me it appears your power stroke lasts longer, which would burn more completely... I'll have to do some more thinking on this one...

Smash

Ah - the Hoser Variable Volume Chamber! I don't see how it could hurt, especially since the piston would be dwelling at the bottom and not providing any reason for the crankcase gases to be moving (other than due to the pressure in the crankcase and the suction that the expansion chamber provided.) Like everything else, I think the Engine ports and timing would have to be optimized for it, but yeah, I think it could only help. The cool thing is that all the conventional 'go fast' ideas (super- and turbo-charging, EFI, variable valve timing, etc.) all can be applied to this crank arrangement.

Smash, you are correct that I'm extending the power stroke - that's the core principal behind the idea. Again, I don't know chemistry, but I'd rather have the temperature of the gas remain in the gas instead of allowing it to soak into the cylinder walls, so the rapid piston movement should help reduce the possibility of detonation. If that's the case, then you can start playing with more compression to get even more power out of the thing.