Volum alfa model

Discussion on Stirling or "hot air" engines (all types)
Horex
Posts: 13
Joined: Sat Apr 08, 2017 8:48 pm

Volum alfa model

Postby Horex » Sun Apr 09, 2017 4:25 pm

hi
Is same volume of cylinders important on a Alfa model?
/johannes

Ian S C
Posts: 1983
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Volum alfa model

Postby Ian S C » Sun Apr 09, 2017 8:00 pm

Horex, yes it seems to be, I dn't know what happens if you try to build for a low temperature, or even if that is possible.
When I built my ALPHA motor, I bored one piece of metal double the length required, then cut it in half to give two cylinders of equal diameter, then made the pistons to fit.
Ian S C

cbstirling2
Posts: 119
Joined: Sat Dec 17, 2016 9:35 pm

Re: Volum alfa model

Postby cbstirling2 » Mon Apr 10, 2017 5:50 am

As for low temperature, the phase angle matters: http://www.stirlingengineforum.com/view ... f=1&t=2206
With a gamma Ltd, the cylinder volume between the hot and cold sides is the same as well since both are contained in the displacer cylinder. Since the pressure differential from LTD Motors is very small the power cylinder is very small.
With an alpha motor you can feel the compression from turning around and that is the pressure differential that is used. But if you change the phase angle that will have an effect on that pressure differential.
CBStirling2

Horex
Posts: 13
Joined: Sat Apr 08, 2017 8:48 pm

Re: Volum alfa model

Postby Horex » Tue Apr 11, 2017 4:49 pm

I made a new cylinder, so both are now ca 4 ccm. But the motor will not run.
Some one told me that altitude over sea level can make problem. I live at 2200 meter.(Mexico) Have someone heard about that ?
/johannes

cbstirling2
Posts: 119
Joined: Sat Dec 17, 2016 9:35 pm

Re: Volum alfa model

Postby cbstirling2 » Tue Apr 11, 2017 8:40 pm

Please post a picture.
With the head vented, the flywheel should spend like crazy.
With the cylinder head sealed, the piston should not slide out on its own.
CBStirling2

Ian S C
Posts: 1983
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Volum alfa model

Postby Ian S C » Tue Apr 11, 2017 11:54 pm

The altitude shouldn't make too much difference (I think)the ratio of the internal: external pressures is the important thing, and although the pressure is lower, the ratio will remain the same. Someone else may know better.
Ian S C

Horex
Posts: 13
Joined: Sat Apr 08, 2017 8:48 pm

Re: Volum alfa model

Postby Horex » Wed Apr 12, 2017 5:44 pm

Hi
Here is my Alpha motor. Same volume on both cylinder (4ccm), much more running friction with all parts connected.
The "regenerator" is only wood, to stop heat on the surface of the metal pipe to go between cylinders.
Attachments
s24.JPG
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cbstirling2
Posts: 119
Joined: Sat Dec 17, 2016 9:35 pm

Re: Volum alfa model

Postby cbstirling2 » Wed Apr 12, 2017 7:47 pm

Very good looking model. Thinking the issues may be air leaks or friction...
I worry about the wood sealing, I'd use hose instead.
If you remove the transfer pipe, does the engine freely spin with almost no friction?
While it madly spins frees, if you block the ports does the engine quickly stops?
I would only use graphite lubrication.
CBStirling2

Horex
Posts: 13
Joined: Sat Apr 08, 2017 8:48 pm

Re: Volum alfa model

Postby Horex » Wed Apr 12, 2017 9:13 pm

The stroke is 20 mm, diameter 16 mm. Wrong relationship ?
The cylinder top on the warm cylinder is made of steel, I think it will keep holding the heat from the flame.
The length of the pistons is maximal.
The flywheels is heavy so it can keep holding the speed.
It is big different of "friction" with/without transfer pipe or cylinder top.
Shall the pistons be as light as possible? I am using iron. Can I use aluminium ?
I have used motor-oil in the cylinder, but I will try to find graphite lubrication. Do you have some idea of what I can use?
Shall the top of the warm cylinder wall be as thin as possible?
Can I put something between cylinder and the top so it will be absolute no leak?
Best from
Johannes

Ian S C
Posts: 1983
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Volum alfa model

Postby Ian S C » Thu Apr 13, 2017 3:17 am

It is normal to have what is known as a Heylandt Crown on the hot piston, this is a thin walled hollow cylinder similar in construction to the displacer in a BETA, or GAMMA motor, in your motor it would be about 14 mm diameter, by about twice that long. The transfer port comes out of the cylinder at the TDC of the compression part of the cylinder(about half way up the cylinder. this would allow for better heating of your motor without the heavy cylinder head.
This is my Ross Yoke ALPHA motor, the transfer port is in the cylinder head that covers the cold cylinder, and is at the base of the hot cap on the hot cylinder.
Ian S C
[img]
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Ian S C
Posts: 1983
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Volum alfa model

Postby Ian S C » Fri Apr 21, 2017 6:24 am

Just done a rough sketch of a Heylandt Crown.
Ian S C

Ian S C
Posts: 1983
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Volum alfa model

Postby Ian S C » Fri Apr 21, 2017 6:28 am

Just done a rough sketch of a Heylandt Crown. The top may be attached with high temp shaft lock adhesive of the Loctite type. Ian S C
[img]
IMG_20170421_0002%20(640x585).jpg
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Horex
Posts: 13
Joined: Sat Apr 08, 2017 8:48 pm

Re: Volum alfa model / Heylandt Crown

Postby Horex » Fri Apr 21, 2017 8:53 pm

Hi Ian
I have made a new drawing, is this a correct understanding from my side ?
Is "Heylandt Crown" the name of the part I put on the top of the cylinder, or the function ?
Shall I warm the cylinder or the hot-cap ?

/johannes
Attachments
HC.jpg
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Ian S C
Posts: 1983
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Volum alfa model

Postby Ian S C » Sat Apr 22, 2017 3:36 am

That's getting near, the piston(LH end)is a sliding fit in the cylinder, and should be about one to one and a half times the diameter long. The heat should be applied to the (RH end), at , and beyond the end of the crown.
Ian S C

Horex
Posts: 13
Joined: Sat Apr 08, 2017 8:48 pm

Re: Volum alfa model

Postby Horex » Sat Apr 22, 2017 9:10 am

Hi Ian and everybody.
How to use Heylandt Crown
Is this drawing better now before I run to the lathe?
All comments from anyone are welcome.

/johannes


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