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]

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.

[Niels Abildgaard]

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.

Thank You for thinking.
Great minds thinks alike
Your idea is almost the same i had when talking of a spark chain

A 0.05mm mowing airgap between cylinder wall and piston in low pressure
A normal spark plug gap 0.5mm on center of top of piston in high pressure
A 0.05 mowing airgap opposite the first on other side of cylinder.

Will be back after some dog walking in wood and put up a sketch.

[Niels Abildgaard]

Those mowing-piston sparkplugs I have drawn up til now are not worth publishing.
The  drawing of a micro CHP plant( at start this topic) has two stationary conventional spark plug holes.
 I stick to that for the time being.

[Niels Abildgaard]

The obvious place to have the ignition system is  in the crosshead rod getting energy from a stationary coil integrated with the gland around the piston rod.
Modern 37mm AA shells have systems that measure nozzle velocity very accurately and set the time fuse.
An ignition system within a crossheadrod of say 12mm dia and mowing 34mm ,must be order of magnitudes easier to make.
I seem to remember a couple of days ago that british electricity system price was 0.7£ per kWh for hours on end.
I gues your system gas price is 0.05£
A combination of baseload(66% of max?) made by nuclear,rest by wind or waves or such a Junkers CHP I propose will be economic optimum.
The numbers needed are staggering.
Old crows that feed here can do worse than discussing future electricity strategy.
Interested?

[gipetto]

That's a good point about a crosshead being suitable for an electricity conduit. i wasn't sure that you were going to use crossheads, considering they add a lot of complexity and unreliability to a gasoline engine.
My father has a share in a windfarm. the turbines are in the megawatt range. I am irish and in the eu so our economic situation is not as bad as the uk. the country does buy a lot of nuclear power from the uk through an interconnector.
I've often thought of building a battery bank from electric car cells and using it to power the farm from 5pm to 7pm when energy is most expensive. My health doesn't allow big projects currently, i lack energy.
I worked on a dairy farm once where they had constructed a generator from a car engine. they had fitted a belt pulley inside the gearbox and used it to drive an over the counter generator. I think if i wanted inexpensive power used auto parts would be the way to go, as they are almost free when they age out of service.
I think it's important to be realistic and realise that hobby engines will never give good service in industrial use.
My neighbour is a carpenter and may have built a wind turbine based on the otherpower.com plan. Lately i've been wondering if it were possible to build such an epoxy type axial generator without expensive magnets by emulating the brushless alternator design. that is to say, use two rings of enamelled wire on the stator instead of the current one. pass a field current into one ring, and draw the output power from another ring. the rotor would have two rings also, but with diodes.

[gipetto]

I came across this video a few minutes ago. it mentions that by rotating the valves like a sleeve valve engine does it is possible to get an increase in efficiency by avoiding ring stiction. I thought of your engine because i reasoned the cylinder could be spun since it lacked a cylinder head.
<a href="https://www.youtube.com/watch?v=yomaQvs0esA" target="_blank">http://www.youtube.com/watch?v=yomaQvs0esA</a>

[Niels Abildgaard]

Thank you for video.
For my paramotor concept and lubricated with bio-de-gradeable oil in raw amounts it is worth a thougth.
For my crosshead  one -family house altar,life saver  much less so.
(The Bristol sleeve valves with lots of ports were not known for  lubrication oil frugality.)
The game here is to make the say 35mm times 2 times 40mm cylinder,piston-rings and crosshead of diamond and  gland
.
Lowest known dry friction  and quite some wear resistance

For better picture and further procedings see link

https://www.homemodelenginemachinist.com/threads/piston-ignition-points.36761/



Donor parts for concept proof engine from cheap Chineese gensets

[gipetto]

I wasn't suggesting that you use sleeve valves in the design, merely that you could rotate the cylinder, either in a reciprocating fashion, with the motion overlapping when the piston comes to top dead center and bottom dead center, or in a single direction of continuous rotation. in theory continuous rotation would be more efficient, but this has an increased complexity.

There are so many different ways to get increased efficiency from an engine. for example i don't know if you are familiar with the jowett jupiter r4. it is an early 4 cylinder boxer ohv that used offset cranks. the clever thing is one pair of cylinders balances the other pair so there's no vibration but quite a large increase in power, comparable to a weak turbo iirc.

If you wanted to you could scale your opposed piston engine up so that it's a two cylinder, then offset both cranks and have one pair of pistons accelerating while the other decelerates. this would only work if the pistons meet in the middle i think.

<a href="https://www.youtube.com/watch?v=hVJntOsL5zk" target="_blank">http://www.youtube.com/watch?v=hVJntOsL5zk</a>