[Enginetuner]

Hello

Sorry my english is very bad. I come from Switzerland

I want built a free piston engine from Stelzer.

http://www.faktuell.de/StelzerMotor/
http://www.stelzer-motor.de/

Who has built this or alike free piston engine?

I am search a drawing about free piston engine.


Why is my last post delete?

regards

enginetuner

[dynosor]

I think you could make your own drawings from the diagrams on this page:

http://www.faktuell.de/StelzerMotor/...ionflash.shtml

I would dimension the design such that the exhaust ports open before the inlet port. The animation shows the inlet port opening before the exhaust.


I see a few challenges with the linear free piston engine concept:

How would one couple the linear motion and turn it into rotation to drive a vehicle?

Also, the operating rod acts as an inlet valve by means of a step in its diameter. The larger of the two rod diameters needs to be a gas tight seal with the inlet port. I don't see how you can maintain a good seal here with low friction unless rings are used. If a ring is used, it will tend to catch as it re-enters the port during the compression stroke.

The diagrams do show a cone combustion chamber, but I think the cone angle at expanded ring diameter needs to be much shallower to cam the rings back down to port diameter without breaking them.

How do you start a free piston engine? If you can couple the pistons to a vehicle transmission, then that same mechanism could be used in reverse to start it.

[Enginetuner]

Hello Dynosor

I want this engine not for a vehicle. I want this engine for a small block-type thermal power station.

I want start the engine with a linear electric generator/engine. A parmanent magnet and a Coil. Neodyn magnet and i make with this generator electric energy.

The seal from intake valve is not the problem. The conic intake canal is not conic but only many canals.

[harryn]

There are a number of groups which are working to improve the free piston engine for generating electricity - same concept as you.

I think they are a very good idea, but in some ways, the horizontal free piston engine is rather complex for a hobby build.

I have toyed with the idea of building one so that it is powered from just one side of the engine.
- The piston would be going up and down vertically instead of horizontally.
- The power stroke would be "going up", and gravity would bring the piston back down naturally after it has reach TDC for compression.
- If it is done right, it might be feasible to stratify the fuel - air mix so that it does not blow so much fuel out of the exhaust during intake - a substantial challenge with current designs.

I am thinking that this will greatly simplify the timing of the ignition and potentially allow a much longer power stroke, which might also improve efficiency. Obviously, the downside is that it will reduce the power output of a given engine size and weight rather substantially, but maybe this is a reasonable approach for a stationary engine - generator.

I noticed that most very large commercial high performance diesel engines use piston speeds of no more than 10 meters / sec to optimize fuel consumption, so that might be a useful data point.
Please keep us posed on

[Enginetuner]

Hello harryn

Thanks for your information.

The small piston speeds (10m/s) is for a long engine live.

This engine is too very nice
http://www.lceproject.org/en/index-en.php.

regards

Enginetuner

[crayner]

Dynosor

The slug in the middle of the rod connecting the two pistons is a magnet and the housing contains a coil of wire - when a magnet passes through the coil a current is induced - this would charge a battery and in turn power electric motors

Sandia labs did extensive mil research on the linear alternator as a means for powering remote cell relay towers - with so few moving parts, they need little to no maintenance and can be run on natural gas. Just the thing to provide backup power to a communications link in the middle of nowhere that normally runs on solar power, in case a large fallout cloud blocks sunlight for say a month or so...

[balsaman]

Must be a real shaker.

Eric

[harryn]

Must be a real shaker.

Eric

I noticed that too - pretty heavy duty vibration isolation. It is also useful to note the comment that it takes a heavy duty controls algorithm to make it all work. The challenge with the combustion from both sides is that the exact piston position needs to be monitored to make it all work.

If you build a free piston engine fired from just one side (and use gravity return), then it is more or less self regulating. I suppose it will be similar to having a 2 cycle jack hammer when running from a vibration perspective.

[crayner]

I've been looking at this one for some time... (18+ months or so) which is how I found the links from Livermore, Sandia and Los Alamos national labs... a strange type of fuel injection computer/controller would control spark - the piston travel obviously would slow with the compression, however, depending on idling frequency (60 HZ or a multiple thereof perhaps?) a combination of compression and detonation/spark advance would reverse the piston assembly.

A start capacitor discharged backwards through the power coil would be the initial compression stroke, making the magnetic slug act as a solenoid.

Main inefficiencies were due to thermal/resistive losses in the coil and the strength/isolation of the magnet - they were playing with superconducting windings and liquid nitrogen, but when you're a physicist employed by a think tank, WTF...

[RICHARD ZASTROW]

A pair of these units in the same block would counter each other, wouldn't they? (similar to flat opposed 2-cycle engines) The origins of "tuned exhaust" was to regulate engines to a certain rpm many years ago. Those were straight pipes of a "tuned" length. These were the precursors to the scavanging reverse cone pipes used on motorcycles, snowmobiles etc. nowdays. (Yes, on 4-cycles as well.)

Interesting engines and concept.

[harryn]

Hi Richard

Depending on exactly how it is built, it is possible to counter the forces, at least in theory. Since the pistons are not mechanically linked with a crankshaft, the timing could be a bit tricky. If the two pistons became sufficiently out of synch that they started generating secondary oscillations, life could get pretty interesting - really shaking.

I was toying around with trying to couple the concept with a homogeneous charge engine concept. This runs more like a diesel in that no ignition system is needed - seems like it would be much easier to control, but who knows when you start finding out what is really needed to make an engine work.

[crayner]

The fun part of this project would be the programming of a multidimensional ignition map to function across altitudes, humidity and cycles per minutes (would it idle at 60Hz or would some kind of phase conversion be needed?) - the speed of the burn in the cylinder is what stops the piston assembly from plowing through the head as well as determining the maximum compression numbers and idle speed - it's almost like taking something that shouldn't work and by applying an embedded system, sensors, etc, forcing it to work (akin to a F117 actually flying)

[RICHARD ZASTROW]

Would opposing compression on opposite end of the cylinder keep the "crash" from occurring? Could the firing be kept in sync by ignition timing? Control cycles per minute to numbers like 3600 (60*60) for 60 Hz? Just a thought, I know less than "0" about electronics/electricity.

[rbyrer]

It looks like it should work fine but I can't understand how you initially get it going.

[riyas]

can u help me 4 the miniproject " study of free piston engine".
i hop u can.
i also need some drawing of the above.

[mepren1]

Probably needs to be 2 cycle in order to provide lubrication for the rod etc, don't ya think

[Andy-7300]

Probably needs to be 2 cycle in order to provide lubrication for the rod etc, don't ya think

In this design there's is no lubrication needed;

http://www.freepistonpower.com/FP3.aspx

[fly_boy_bc]

http://ca.groups.yahoo.com/group/Cfair6/files/

[moha152]

Hello,

please I am looking for plans for this type of engine. where can i find?

regards

Moh