Author Topic: Piston spark ignition points?  (Read 1910 times)

Offline Niels Abildgaard

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Re: Piston spark ignition points?
« Reply #15 on: January 11, 2025, 09:30:31 AM »
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.

Offline Niels Abildgaard

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Re: Piston spark ignition points?
« Reply #16 on: January 12, 2025, 09:40:57 AM »
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.
« Last Edit: January 12, 2025, 09:44:41 AM by Niels Abildgaard »

Offline Niels Abildgaard

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Re: Piston spark ignition points?
« Reply #17 on: January 14, 2025, 03:20:35 PM »
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?

Offline gipetto

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Re: Piston spark ignition points?
« Reply #18 on: January 14, 2025, 06:37:04 PM »
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.

Offline gipetto

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Re: Piston spark ignition points?
« Reply #19 on: January 18, 2025, 07:07:44 PM »
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>

Offline Niels Abildgaard

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Re: Piston spark ignition points?
« Reply #20 on: January 24, 2025, 11:53:06 AM »
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
« Last Edit: January 24, 2025, 05:52:52 PM by Niels Abildgaard »

Offline gipetto

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Re: Piston spark ignition points?
« Reply #21 on: January 24, 2025, 11:06:56 PM »
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>

 

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