IC Engine Testing

please contact me reference simple engines

snipped-for-privacy@tiscali.co.u

-- bolma

----------------------------------------------------------------------- bolmas's Profile:

this thread:

I take it that you are aware that this is not a new invention. I haven't got quotes of the prior art, but have seen articles about it a couple of decades ago.

Mark Rand RTFM

Simple. Take an average modern engine and fit your pistons to it. Do before and after tests on a rolling road of which there are hundreds about. That will still cost a few hundred quid but if you're so sure this works you'll find the money.

Maybe it works at very low piston speeds but not at real life engine speeds. I have no idea but it won't cost much to find out. You could also just time the acceleration over a measured distance and calculate the extra bhp. Most of the equations you need are on my website or the web. Personally I think the major manufacturers would already be doing it if it worked.

Hmm, Ive read the technical bit and I dont see how it could work. Certianly I doubt that anywhere near 30% extra efficiency can be gained from a more mechaicaly complex system. AFAICS you use the explosion to compress a spring and then use the spring to drive the conecting rod (massive oversimplification?) I suppose that at certain resonany frequencys you might get a bit more out from the engine, but it would be a very narrow speed range (frequency). Can anyone enlighten me or is it really a solidified snake oil?

As to prior art I remember seeing an article about this type of thing in Engineering on Campus or some such comic when I was at university, about 1996 iirc.

Dave

Did you get a quite from Ricardo's? hehe. now that will make your eyes water! The company I was involved with sometime ago spent a lot of money there ;-) They eventually employed some of the Ricardo guys.

I've used the 30bhp water brake from Dynomite. OK, except you have very little control over the brake, especially at lower torques. I think that one cost about 3 grand. It's really designed for karting people, not real scientific work.

They replaced it eventually with a more sophisticated Magtrol dyno.

Pleny of 4 stroke model aero engines on ebay. They can be quite useful testbeds especially the larger ones.

Most ideas have been covered sometime or other. I worked with a company (still trading) with a quack engine design (I can say that now ;-) )

It's a tough business to be in fullstop. Getting manufacturers interested is very tough.

In 8 years I saw millions of pounds poured into the idea, and nothing much gained in that time. About the only good thing that cam out of it were fairly good toy engines ;-)

Might be worth the original poster trying to get in touch with UNICEG I think it's managed from Loughborough(sp) uni. There maybe someone in that group willing to help.

Wayne....

In article , Mark Rand writes

As I just posted in another reply, I am fairly new to this myself and not the best person to answer this, but my understanding is that the previous work on sprung pistons was for other purposes, and using quite different designs. The patent work has of course been done by a qualified patent agent. But thanks for the thought anyway.

David

In article , Dave Baker writes

This is also planned, but more difficult to get good quantitative data.

Works fine at 4,000 rpm.

Still, thanks for the thought.

David

In article , snipped-for-privacy@bem.fki-et.com writes

The problem is that in a normal engine the ignition takes place before TDC, and can do no useful work in this position. Thus the gas heats up far more than necessary and loses lots of energy as heat. Storing part of this energy in a spring and releasing it back on the downward stroke enables it to do useful work. The thermodynamics is sound, and it has been shown to work in practice. Tests to date have shown improvement over all the working speed range, though the benefits vary a bit. The problem is designing a spring which is stiff enough and has an adequate fatigue life.

I am fairly new to this myself and not the best person to answer this, but my understanding is that the previous work on sprung pistons was for other purposes, and using quite different designs.

David

In article , Wayne Weedon writes

Indeed so; they are one of the companies I referred to!

Interesting thought; we had been looking at lawn mower engines. Of course, I should have mentioned we need a 4-stroke engine.

Thanks for the input.

David

I have to resist to comment that.

Dynos should be available used. Schenck is one of the manufacturers. They also can be made by oneself, depending on the size of engine you want to test. There are several principles: A brake (hard to get the heat away) A water brake (like a pump with adjustable loss) An electrical dyno and cooled resistors An electrical brake (howsthatcalled. It is a slotted disk rotating in an magnetic field).

HTH, Nick

Ok, I think I follow that. Thanks for the explaination. Its not very clear on your website, whcih is where my confusion came from.

Dave

That still is true for the spring piston.

That still is true for the spring piston. OK, it reduces the compression*) and thus the efficency.

The gas is the spring. It stores the energy (not as good). In the down stroke, when the spring releases, it increases the pressure/temperature and thus will increase the loss. The problem with the biggest force in TDC has already been addressed with desaxiated crank shafts and con rods with a joint (and an additional lever).

Temperature, number of cycles and wheight will kill that design. BTW: How do you prevent the piston from rotating? What with the air being pumped in and out of the piston and making losses?

*) Would require some math. Are you aware that we are talking about accelerations of the pistion in the ballpark of 10000m/s^2? Yes, g = 9.81m/s^2. 30000m/s^2 is considered the maximum allowable. 1000 times normal the wheight of the piston will strech the spring, the gas pressure should be to low to compensate that. Thus you are increasing the stroke of the engine.

Nick

In article , snipped-for-privacy@bem.fki-et.com writes

Dave,

I didn't write the website - I've only been involved for a few weeks - but I will pass the comment on, thanks.

David

Is this an 'Atkinson Cycle' engine? as at

expands the power stroke, much like running a steam engine notched up, so the expansion of the gas does more work. Is the spring top piston not actually shortening the induction stroke, and thus doing the same sort of thing?

Dave

David,

Get yourself a 4 stroke motor generator setup, and use the generator as your dynamometer. Easy to vary the load. (You may need to knobble the AVR driving the generator field though)

AWEM

A bit of. But the Atkinson has a much better compression/expansion index. And it does the 4 strokes in one revolution of the crank. That (compression/expansion) is much easier solved with the miller-cycle. The setup with the conrod with a link and a lever has a different name that I can't remember.

Guestimating, I think the stroke gets longer (the acceleration is about

1000 of earth's accel.). I would need more numbers to calculate that, but I think the electrical engineers already solved all that mechanical crap in the first 5 minutes. :-)) It also will be interesting to hear how the piston sounds when it hammers against the stop-ring that is at the bottom of the piston shown on the site. Or how that sounds when the ring finally is falling out. Or how the valves sound when they hit the piston because the pockets (or dome) on its head rotated.

Nick

Eddy current brake.

David did you see my reference to UNICEG? Universities Internal Combustion Engine Group.

They are quite a helpful bunch of engine people. The group also has members from just about all main car companies.

For engine people the presentations often held at various uni's are very interesting. Last one I went to was at Kings College in about 2002, presentations from memory were from Ricardo's, Lotus, Ford, and a couple of barking mad engine designers including the one I worked for!

I also have fairly good relationships with a couple of ex ricardo people, who are quite helpful.

Wayne...