Piston spark ignition points?

[Niels Abildgaard]

I am using the last part of life for walking my dog and save humanity.
One idea is to make  4/6 kW combined power and heat from gas put  in an opposed ,crosshead Junkers scheme when other sources are down or to expensive
and
the other is a powered paraglider poweplant of ca 20kW.
Both will benefit enormeously if ignition points can sit in center of pistons.
Has this been solved before and where?

[Admiral_dk]

Hej Niels

I have honestly only seen this with a single piston - where one Point was part of the Piston (ground Electrode) and placed as a tip in the middle.

Haven't got a clue right now on how to for instance isolate a complete ; Crank, Rod (easy) and piston from the rest Electrically - and basically will have to rule that option out.

Having just the Centre Electrode poking out into the Middle from the Cylinder Wall - might be feasible - but not with Phased Cranks (unless you can live with a very low compression ration) ....

So how about CI (Compression Ignition) - like Model 'Diesels' ...???
They are very efficient and simple - except when you want 'Variable Compression' with a dual Crank ....

Per       

[gipetto]

gasoline direct injection i believe it's called in modern vehicles. it's used in hyundai's hilariously unreliable theta 2 engines. it does work but the gasoline vapour tends to strip the lubricating oil from the cylinder and the vapour enters the sump leading to accelerated engine wear.
Hears a weird idea though. suppose you put a magneto and spark plug inside a piston, then a magnet inside the cylinder liner to trigger it. it would have to withstand the heat of combustion.
there was also a thermonuclear internal combustion design that used lasers through a glass aperture to ignite a fuel pellet through fusion.

[Niels Abildgaard]

I have honestly only seen this with a single piston - where one Point was part of the Piston (ground Electrode) and placed as a tip in the middle.

Hello Per

Was it SAAB and when?

[Niels Abildgaard]

Hears a weird idea though. suppose you put a magneto and spark plug inside a piston, then a magnet inside the cylinder liner to trigger it. it would have to withstand the heat of combustion.

there was also a thermonuclear internal combustion design that used lasers through a glass aperture to ignite a fuel pellet through fusion.

Not so weird idea.

Some 35mm AA gun shells have exact velocity measured and wanted fuse setting done when leaving barrel.

Laser ignition is difficult due to dirtying of window ater more than a few ignitions

[Roger B]

All the succesful opposed piston engines I am aware of have been two stroke diesesl (generally following Junkers). There were a couple of early 4 stroke gas/petroleum engines, one of which used hot tube ignition (Saurer).

How about a Piezo ignition module in the crown of the, hopefully cooler, inlet piston operated by a push rod from the exhaust piston approaching TDC.

[Admiral_dk]

I honestly don't remember who made the Piston as part for the Plug (so to speak) - but SAAB is a good bet - they where rather inventive ....

I can't see an Ignition system integrated into the Piston being a reliable option - all those vibrations have a very negative effect ....

I don't see Rogers option having a variable Timing option ....

Per   

[Niels Abildgaard]

All the succesful opposed piston engines I am aware of have been two stroke diesesl (generally following Junkers). There were a couple of early 4 stroke gas/petroleum engines, one of which used hot tube ignition (Saurer).

How about a Piezo ignition module in the crown of the, hopefully cooler, inlet piston operated by a push rod from the exhaust piston approaching TDC.

Quite some Fairbanks Morse OP engines are or have been sold for natural gas with spark ignition methinks.
Piezzoes are in consideration.

[Roger B]

This company, Enginuity Power Systems, seems to be some way along the CHP path with an opposed piston 4 stroke. Here is a diagram of their system and a couple of links. As it is a 4 stroke there seems to be space for a conventional spark plug.

https://www.nature.com/articles/s41467-024-48627-0

https://enginuitypowersystems.com/about-us/technology/

[rdean33422]

I have been following this thread and I may be confused but this is a 2 piston, 2 crankshaft, opposed model I built a while back.

<a href="https://www.youtube.com/watch?v=n1f60qCrowM" target="_blank">http://www.youtube.com/watch?v=n1f60qCrowM</a>

I may have completely misunderstood so just disregard if I did.
Ray
.
 

[gipetto]

niels is trying to improve the efficiency of the opposed piston engine. there's nothing wrong with that, if he doesn't get trapped in a money pit.
As regards the electric isolation spark problem, I guess you could isolate one side of the engine from the other, by using viton rubber rings on the pistons, and an insulator on one end of the cylinder liner.
Another approach is to not do any isolation, and instead ensure every part has an electrical connection. Then instead of using dc or ac to make the spark use radio frequency. I have enclosed a picture of an antenna i once built. you can see that below the coaxial feedpoint there is a bridge between both sides of the antenna. That is one of the mysteries of rf, because what appears as a short at dc is an insulator at rf, so you may be able to add some tuning stubs to the engine to create the necessary electrical isolation.

[Niels Abildgaard]

I have been following this thread and I may be confused but this is a 2 piston, 2 crankshaft, opposed model I built a while back.

<a href="https://www.youtube.com/watch?v=n1f60qCrowM" target="_blank">http://www.youtube.com/watch?v=n1f60qCrowM</a>

I may have completely misunderstood so just disregard if I did.
Ray
.

Hello Ray

Much noise about nothing but lovely.
Flywheels live from mass and rps.
Big flywheel split in two and put on each crank give more uniform running , good for both generator or prop drive.
When You are at modifying it cross the chain and perfect balance can be achieved.

[Niels Abildgaard]

niels is trying to improve the efficiency of the opposed piston engine. there's nothing wrong with that, if he doesn't get trapped in a money pit.
As regards the electric isolation spark problem, I guess you could isolate one side of the engine from the other, by using viton rubber rings on the pistons, and an insulator on one end of the cylinder liner.
Another approach is to not do any isolation, and instead ensure every part has an electrical connection. Then instead of using dc or ac to make the spark use radio frequency. I have enclosed a picture of an antenna i once built. you can see that below the coaxial feedpoint there is a bridge between both sides of the antenna. That is one of the mysteries of rf, because what appears as a short at dc is an insulator at rf, so you may be able to add some tuning stubs to the engine to create the necessary electrical isolation.

Thank You for interest and proposals.
I have seen pictures of ball bearings destroyed by sparking and my micro CHP shall run hours without attention.
I hope that a high tension chain over two moving isolated 0.05mm airgaps between piston and cylinder wall in low pressure zone and a high tension spark gap in piston center could work .
Same technology as in old fashioned distributors  on V-8 and the like.
Worth trying and if not working no disaster

[Niels Abildgaard]

It is many years since I have seen the inside of a spark distributer between coil and 4 sparkplugs.
What was the gap materials and how wide was the rotating gap?


Next problem is where to put the two sliding gap per piston in my world saving  crosshead opposed piston configuration?
In crosshead/crank sections or between the  the glands in the cylinder division?

In crosshead chambers we can have a non ignitable lubricant.
In the cylinder division there will be lots of ignitables and fuel.
One can argue that the width of the sliding low pressure spark gaps can be kept down to 0.05mm so the sparks can easily jump but not ignite anything or it does not keep burning like in a miners safety lamp.

A single cylinder opposed piston engine (Junkerator) can make the most efficient EV-range extender if we can integrate swishning and ignition in the two opposing pistons.

If someone wants richness and fame start Googling   


   Drallmeier  and opposed piston


  Interesting reading

[gipetto]

I find some of your concepts difficult to understand, i believe it to be a language issue and illustrations would clarify your comments. i am having trouble with your high tension chain spark.
Here's another idea, suppose that you moved the cylinder with a crank and con rod, so the spark plug location was kept between both pistons. you could mill a relief in each piston, and have the plug protrude half ways into the cylinder.
Another idea is to make a piston with a partial spark plug inside it. the electrode would be at the center of the piston, and have an ceramic tube and metal rod that moves radially outward to where it brushes against a contact in the cylinder liner.
The cylinder liner also has a ceramic tube and metal contact, so that when both contacts touch and the timing is correct the spark is fired.
The advantage of this approach is that you could change the spark plug without tearing down the engine, since all that you would need to do is ensure that the cylinder plug is over the piston plug before unscrewing them. This is similar to how the wrist pins are removed on some subaru boxer engines.