Author Topic: Low noise Two stroke? (Read 15368 times)

Niels Abildgaard · « **on:** January 11, 2015, 07:35:06 AM »

Shown here is a proposed 24 times 24 mm engine that is different.

Roger B · « **Reply #1 on:** January 11, 2015, 07:45:36 AM »

Are you using the poppet valve for the exhaust like the GM two stoke diesels?

Niels Abildgaard · « **Reply #2 on:** January 11, 2015, 08:51:32 AM »

Quote from: Roger B on January 11, 2015, 07:45:36 AM

Are you using the poppet valve for the exhaust like the GM two stoke diesels?

Most two stroke diesels to day have exhaust valves,but not actuated directly from crank and not as sidevalves.
Pistons are not really good at controling unsymetric exhaust.

Allen Smithee · « **Reply #3 on:** January 11, 2015, 09:10:03 AM »

An interesting concept Is it intended to have rear disk/drum valve induction - if so what is the reason for the hollow crankshaft? I'm not sure you'd get away with the short piston at these sizes; it ma need a longer skirt.

My only other thought would be that the exhaust valve looks rather small compared to the sort of size exhaust port you'd typically see on an engine like this.

AS

Niels Abildgaard · « **Reply #4 on:** January 11, 2015, 10:27:16 AM »

The hollow crank is a leftover from having normal crankwindov inlet.
Away with that.
The Piston guiding length is around 20 mm compared to 24 mm diameter.No standard car pistons are more I think.
The valve is half bore diameter.
The normal two stroke exhaust port is going down to piston edge at lower dead point mostly to avoid burning.It is the blowdovn area that is important.

lohring · « **Reply #5 on:** January 11, 2015, 06:00:41 PM »

You are throwing away a good combustion chamber shape with the flat head design. It's tough to beat the rapid opening and high flow of piston controlled ports, especially with the high frequency of cam operated valves. Poppet valve engines have mostly been used on lower speed engines. The double piston engine has more potential for high power in a uniflow design.

The sleeve valve two stroke has many of the advantages of a double piston in a single cylinder uniflow design, but was never fully developed. See http://www.modelenginemaker.com/index.php?topic=4395.0 I wouldn't think a two stroke sleeve valve would be harder to make than a poppet valve with its cam. The sleeve can be operated with an eccentric on the crankshaft with a link to give the sleeve a rotary and reciprocating motion like the dummy piston on the Crecy. Ricardo used this mechanism on his single cylinder test engines. See http://www.amazon.com/High-Speed-Internal-Combustion-Engine/dp/B001TGPTGE/ref=sr_1_1?s=books&ie=UTF8&qid=1420998982&sr=1-1&keywords=ricardo+high+speed+internal+combustion+engine For a detailed description of the test program that lead to the Crecy.

Lohring Miller

Niels Abildgaard · « **Reply #6 on:** January 11, 2015, 07:11:07 PM »

Hello Lohring

Easy, it is just a game and nobody has been robbed yet.
Your arguments about chamber design is surely Right but are Briggs and Stratton sidevalve engines copies still being made in big numbers?
A two stroke of this kind can maybe be better than B&S SV engines.
Let us compare
Both have 4 bearings
2 for crank and either 2 for camshaft(B&S) or two for balanceshaft.
Two gearwheels .Crank and either cam or balanceshaft two cams and valves versus one of each
Exhaust noise equal as same amount goes through exhaust valves.
If the new can use 1% oil /fuel , real oil pollution will be less.
I was visiting a Chinese homepage that offered two stroke moped cranks for 2$ (and for BMW FS650 for Fifteen.)
If the new one can be lighter and much less harsh, lawnmover engineers will raise their hands in joy.

Niels Abildgaard · « **Reply #7 on:** January 12, 2015, 04:47:40 AM »

Hello Allen and Lohring

If You see a two stroke cylinder as a volume between two restrictions ,inlet and exhaust,it will be obvious that the exhaust shall be smaller than inlet to reach max charge.What the valve does is most likely to make tuned exhaust strategy valueless.It is the very violent blowdown that keep tuned pipes going energywise.It is also the very same violence that makes port exhaust noissy.On the plus side for an exhaust valve is that timing can be unsymetric.
I still think it looks lovely.
Some belgians make sidevalve aircraft engines and claim better fuel consumption than Rotax 912.

http://www.d-motor.eu/nl/fuel-consumption-110.htm

lohring · « **Reply #8 on:** January 12, 2015, 03:08:40 PM »

I'm obviously trying to get someone to build a sleeve valve two stroke. I was inspired by Ricardo's book in the late 1950s. There have been several model four stroke sleeve valve engines built, a much more difficult problem. Briggs and Stratton engines are designed for low cost, not high performance. The flat head Ford V8 is similar. You can't get the high compression and large valves that high performance engines need in a flat head. If you aren't worried by performance, any number of designs will run.

Lohring Miller

Allen Smithee · « **Reply #9 on:** January 12, 2015, 05:02:52 PM »

Quote from: lohring on January 12, 2015, 03:08:40 PM

If you aren't worried by performance, any number of designs will run.

...most of them built and sold by Vauxhall

AS

dieselpilot · « **Reply #10 on:** January 12, 2015, 05:05:09 PM »

Lohring, I've been throwing around the sleeve valve two stroke idea for a while. It would be just for fun though.

Niels Abildgaard · « **Reply #11 on:** January 12, 2015, 06:14:34 PM »

Hello Lohring

I have the RR Crecy two stroke sleeve valve book.It could be heard in Lands End when being tested in Derby.
British sleeve valve development was a dead end and probably a rather expensive one.
Nothing that was done by Bristol sleeve valves was not equalled by normal valves and the napier things where grounded soon after war end.
My two stroke sidevalve proposal can surely have a higher compression ratio than Harleys as there is only one valve.
A belgian 60 kW sidevalve aircraft engine claim 260 gram per kWh and weigh 1 kg per kW.This is on par with the top of the pop Rotax 912 that uses 280 gram.The watercooled Continental that circled the world was more mass but used only 240 at best point.
My sidevalve two stroke is better than your sleevething.

Niels Abildgaard · « **Reply #12 on:** January 13, 2015, 11:57:35 AM »

Mass produsable singlesidevalvesingle.
The camcrank is not for amateurs

Allen Smithee · « **Reply #13 on:** January 13, 2015, 02:33:40 PM »

Why not?

AS

lohring · « **Reply #14 on:** January 13, 2015, 02:55:14 PM »

It's ironic that I'm building an engine of almost exactly your same design. It's a two stroke, but it is a flash steam engine. That layout has become almost standard in "modern" flash steam engines. See http://www.modelenginemaker.com/index.php?topic=2760.0 Here, compression isn't as much of a factor and simplicity is. Low valve train inertia helps at 10,000 rpm. A long valve stem is also a plus to seal the 1000+ psi steam. The piston and materials are much different.

The last big aircraft piston engine designs mostly used sleeve valves, even in the US. Most were never built and the turbine made them obsolete in any case. There were a lot of advantages, especially in cylinder wear and combustion chamber design. The sealing problems were solved, even in air cooled cylinders. Except in aircraft piston engines, there was never much incentive to explore radical new designs after the 1920s. All the engines actually used in WW II were 1930s designs at the latest. Today you get a lot bigger benefits from electronic engine management. The cost to change engine manufacturing lines is huge. Some of the push rod V 8 engine designs date from the mid 1950s.

Good luck

Lohringh Miller

BillTodd · « **Reply #15 on:** January 13, 2015, 03:04:55 PM »

The more I look at it the more I like it Niels

Opening the exhaust later and slower than a conventional piston-ported two-stroke should make it considerably quieter.

If it needs a bigger exhaust flow you could easily double up on the valves.

There's a bit about tuning side valve heads in the classic 'tuning for speed' book - I'll scan anything of interest for you.

Bluechip · « **Reply #16 on:** January 13, 2015, 03:18:26 PM »

Quote from: BillTodd on January 13, 2015, 03:04:55 PM

The more I look at it the more I like it Niels Opening the exhaust later and slower than a conventional piston-ported two-stroke should make it considerably quieter.

If it needs a bigger exhaust flow you could easily double up on the valves.

There's a bit about tuning side valve heads in the classic 'tuning for speed' book - I'll scan anything of interest for you.

Download whole book here in .pdf.

http://tuningforspeed.com/

Dave

Niels Abildgaard · « **Reply #17 on:** January 13, 2015, 04:19:27 PM »

Dave That's a lovely book and I would have payed for it if I had known it existence
Bill thank You for remembering the title
Lohring Thank You
AS Hardened and profile ground?

Allen Smithee · « **Reply #18 on:** January 14, 2015, 08:11:56 AM »

Quote from: Niels Abildgaard on January 13, 2015, 04:19:27 PM

AS Hardened and profile ground?

Yes, but that's not the only way of making it. It wouldn't be that difficult to make the cam as a separate part and silver-solder, weld, bolt or even glue it in place.

PDR

Niels Abildgaard · « **Reply #19 on:** January 14, 2015, 10:16:58 AM »

Hi Allen
You are of course rigth and I am trying to make counterbalance shaft drive gearwheel and cam as one part.Up til now it has looked horrible.

Niels Abildgaard · « **Reply #20 on:** January 15, 2015, 09:36:49 AM »

With the camgear and balanceshaft and exhaust valve more or less as shown the following benefit for mankind can be had.
Vibration as a four cylinder fourstroke(almost).
Fuel wastage between the 40% of a simple twostroke and the 10- 20 % of a normal fourstroke.
Lubrication 2 % oil in gas (If cam and valve allow it).
Different

Niels Abildgaard · « **Reply #21 on:** May 17, 2015, 01:14:33 PM »

Have made a little progress but need to find a bigger (44-48 mm) dia piston (two or four stroke) with a 12 mm wrist pin hole.
The first order mass balance is not important in first try.

Admiral_dk · « **Reply #22 on:** May 17, 2015, 03:06:20 PM »

Hej Niels

It looks like you're using moped parts as crank and piston - nice crankcase

Looking forward to see the rest of the story.

Mvh Per

Niels Abildgaard · « **Reply #23 on:** May 17, 2015, 03:54:13 PM »

Hello Per

If somebody like the shown lot they can have it free.
Am getting older and have to get rid of surplus.
I am more tempted to make something of the next lot shown below.
The crank is modified so that it balances as an inverted V2 90 degree as shown with the pistons on picture.
By playing around with piston diameter difference and cam profiles it must be possible to equalize output from two cylinders eating from a common crankcase.If one spark plug cable is disconnected rpm shall be same whatever cable.

Niels Abildgaard · « **Reply #24 on:** May 17, 2015, 08:24:49 PM »

The shown crankshafts are from Poland and cheap.
Stroke is 44 mm.

There is another source of two stroke parts here:

http://www.agm-engine.co.uk/accessories-c-72.html

from a AGM30 motor with 30mm stroke.Try and se what a complete ignition system cost.
I have ordered two cranks 26 euro each and not much postage from HongKong.
It will be interesting to try and make a normal doublesided crank,ie how accurate the two parts are relative to each other.
If OK I will count AGM30 cranks instead of sheeps when going to sleep.

Niels Abildgaard · « **Reply #25 on:** November 20, 2015, 11:16:39 AM »

A further phantasy

lohring · « **Reply #26 on:** November 20, 2015, 04:33:14 PM »

An update on the sleeve valve two stroke:

A video of a modern two stroke engine by the incredibly talented Neil Hintz (pictures below):

<a href="https://www.youtube.com/watch?v=qDjG4bNCLWw" target="_blank">http://www.youtube.com/watch?v=qDjG4bNCLWw</a>

<a href="https://www.youtube.com/watch?v=bwsu5td6nko" target="_blank">http://www.youtube.com/watch?v=bwsu5td6nko</a>

From Harry Ricardo's testing

lohring · « **Reply #27 on:** November 20, 2015, 04:36:35 PM »

Pictures as promised:

BillTodd · « **Reply #28 on:** November 20, 2015, 07:01:24 PM »

The afore mentioned Crecy:

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

Roger B · « **Reply #29 on:** November 20, 2015, 07:25:19 PM »

Amazing work on that sleeve valve two stroke

something to aspire to

Niels Abildgaard · « **Reply #30 on:** November 20, 2015, 07:39:31 PM »

The Crecy was not low noise and the crankcase oil stayed golden.
This means that all piston and sleevevalve lubricant took the easy way out.
Some pollution

BillTodd · « **Reply #31 on:** November 21, 2015, 12:59:04 PM »

Quote from: Niels Abildgaard on November 20, 2015, 07:39:31 PM

The Crecy was not low noise and the crankcase oil stayed golden.
This means that all piston and sleevevalve lubricant took the easy way out.
Some pollution

All true Neils, but then the crecy was for military use and they just didn't care

Just thinking , given that you are trying to design a relatively low performance, quiet and clean two stroke (i.e. something ideal for portable generators etc.). How about a stepped piston (twin) design, so you can separate the crankcase oil ?

Your poppet valve and cam might need some pretty good lubrication, which would be potentially smokey if in a petroil mix.

Niels Abildgaard · « **Reply #32 on:** July 24, 2022, 01:42:25 PM »

Please find the papers from a two stroke lovers get together 2020

https://drive.google.com/drive/folders/1YNYWcnGSqsfYqu_EV1XM_g0HQ9pOxbmv

Niels Abildgaard · « **Reply #33 on:** June 19, 2023, 04:24:21 PM »

Until some prior art can be found I feel very proud as spiritual father of this:

https://www.fvt.at/ka/en/references/layout-and-design-of-an-innovative-range-extender-engine.html

My first written describtion is this I seem to remember

https://www.homemodelenginemachinist.com/threads/sidevalve-single.23909/#post-258381

If You know of some prior art please let me know as roof/ceeling here in house is getting uncomfortably low.

Niels Abildgaard · « **Reply #34 on:** June 29, 2023, 07:34:14 PM »

The austrians from the above link are working to dominate future EV car range extenders.

They have claimed more than once that crankcase charging will not allow a three-way catalyst so they do it the Detroit diesel way.

Is it true?
By crankcase scavenging with air only and total loss lubrication about 1% of fuel amount it hard to imagine that catalyst cannot burn that?

https://drive.google.com/drive/folders/1YNYWcnGSqsfYqu_EV1XM_g0HQ9pOxbmv

Kirchberger Graz

Admiral_dk · « **Reply #35 on:** June 29, 2023, 09:15:20 PM »

Hi Niels

I might be reading this wrong - but beside a kind of Fuel / Range Extender - nothing much has come from all these studies, that will see us having a Two-Stroke in our next wheehicle ....

I have ambivalent relationship to Two-Strokes, as I loved to ride them in my youth, but also tired of all the extra maintenance / lower reliability, compared to Four-Strokes ....

Mvh Per

AlexS · « **Reply #36 on:** July 11, 2023, 10:58:17 AM »

Interesting documents you shared.

Ah if used as range extender for fixed rpm and load it might work out. And as UNIMORE showed a separated oiling system. And ad Kirchberger showed a Uniflow exhaust valve setup.
Only maybe have to test it with trying to use hydrogen or a blend for combustion this should give a weight/power output. I know you can generate electricity form hydrogen fuel cells. But there you have to condition the PEM cells and require (as far as I know) platina or similar resources (availability?).
So as second option?

Niels Abildgaard · « **Reply #37 on:** July 11, 2023, 01:14:50 PM »

Quote from: AlexS on July 11, 2023, 10:58:17 AM

Interesting documents you shared.

Ah if used as range extender for fixed rpm and load it might work out. And as UNIMORE showed a separated oiling system. And ad Kirchberger showed a Uniflow exhaust valve setup.
Only maybe have to test it with trying to use hydrogen or a blend for combustion this should give a weight/power output. I know you can generate electricity form hydrogen fuel cells. But there you have to condition the PEM cells and require (as far as I know) platina or similar resources (availability?).
So as second option?

I think it is the real solution and my question is if the charge free crankcase is nessecary for going threeway catalysing.
The main road is to keep charge low(MEP =6bar), and uniflow.In that case a V2 with common crankcase
will be much simpler and lower mass.
Click on the picture and open in another window
It shows a comparison of a crankcase scavenged 100/150 mm bore/stroke cylinder with a blower fed doing same work

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Author Topic: Low noise Two stroke? (Read 15368 times)