WIP plans: sleeve valve single

Nerd1000 · Tuesday at 8:14 AM

I've been working on this on and off for a while, but since moving to Germany I can't work on my diesel project so I've gotten back to it. Basic parameters are a bore and stroke of 32mm for 25cc total displacement.

Sleeve valves work by moving up and down and oscillating from side to side driven by a crank mechanism. The timing is set by the movement of the sleeve and the ports cut into it. Given that this is to be a fairly low speed model, I wanted pretty mild timing which works out to smallish ports. The sleeve is driven by a peg that slides in a bronze ball. Note the junk head (basically a fixed piston complete with rings that acts as the cylinder head).

If it works out, I'd like to have the possibility of making a 3 cylinder radial version. What's puzzling me a bit is the inlet and exhaust layout, I'm not sure the best way of hooking all the ports from a round cylinder to a single carb and exhaust. Anyone got suggestions?

lohring.miller · Tuesday at 10:56 AM

Below is how the Bristol and similar sleeve valves were laid out. The common port allows an easier manifold design. See https://www.enginehistory.org/members/articles/Shilling.shtml for information as well as pictures.

Lohring Miller

Nerd1000 · Wednesday at 2:25 AM

lohring.miller said:
Below is how the Bristol and similar sleeve valves were laid out. The common port allows an easier manifold design. See https://www.enginehistory.org/members/articles/Shilling.shtml for information as well as pictures.

Lohring Miller
View attachment 162683

Yes it let them space out the ports in the cylinder evenly. My design has the same approach but the smaller ports mean the two that would make the common port in the sleeve don't quite meet up

Peter Twissell · Wednesday at 10:11 AM

I'm not sure I understand the question but...

If your ports are smaller for mild timing (i.e. zero overlap?) then it is to be expected that the cylinder inlet and exhaust ports do not both meet up with the sleeve common port.

Are you asking for suggestions on the cylinder / sleeve port locations, or manifold design?

Nerd1000 · Wednesday at 10:59 AM

Peter Twissell said:
I'm not sure I understand the question but...

If your ports are smaller for mild timing (i.e. zero overlap?) then it is to be expected that the cylinder inlet and exhaust ports do not both meet up with the sleeve common port.

Are you asking for suggestions on the cylinder / sleeve port locations, or manifold design?

Manifold mostly. I'll mess with some ideas and see how they look I think.

Peter Twissell · Wednesday at 11:21 AM

Ok, here's a suggestion:
On the outside of the cylinder, machine channels which extend downward from each inlet port and upward from each exhaust port (or vice-versa). Machine a manifold ring with two annular grooves on the inside diameter, so that when it is pressed onto the cylinder, one groove communicates with the inlet channels and the other communicates with the exhaust channels.
The manifold ring would need a land between the grooves wide enough to cover the ports themselves.

Better gas flow might be achieved if the ports were machined through the cylinder wall at angles, e.g. exhaust ports machined so that they emerge through the outside surface of the cylinder at an upward angle and inlet ports at a downward angle. This would allow for a narrower land between grooves in the manifold ring.

Depending on your preferred fuel and use of this engine, it may be preferable to use the ring for inlets only and fit seperate exhaust headers, to improve exhaust heat rejection and allow for more finned are on the cylinder. This would be closer to the Bristol Centaurus design.