6 Cycle Internal Combustion Engine

[Rdean33422]

I have seen engines where there is one cylinder and one piston but each end of the cylinder is a combustion chamber. The engine fires on both sides of the piston. This interested me so I looked deeper into the design and found there are several engines using this system and at first glance I thought I can make this. No problem.
Boy was I wrong as this design brings up several major problems. At first I thought I could just treat each end of the cylinder as a separate 4 cycle engine and use a distributor to control the spark. Use a side shaft with two cams at a 2 to 1 ratio of the crank shaft for the exhaust valves. What I found was that no mater how you configured the valve timing there would be a cycle when one side had fired and the other side was starting into compression. Most of the power from the first side would be lost.
Back for more research and found that several of these engines use 6 cycles.

Power
Exhaust
Exhaust
Exhaust
Intake
Compression

Yes the exhaust valve is held open for 1 1/2 revolutions or 3 strokes but you have to remember that there are two combustion chambers and as they overlap so the idle time is not too long. There are other ways of making a 6 cycle engine also but this is the way I'm going to attempt to do it. Attempt is right as there are many different operations I have never done before such as the valve timing for the 6 cycles.
The cam shaft now will make one revolution for every three revolutions of the crank shaft.

I'm just going to jump right in and see how it goes.

I salvaged a nice 10mm shaft from a hydro window opener or supporter.


I turned a piston from a piece of aluminum and with a light press and some red loctite positioned it in the center of the rod.


I bored 2" aluminum cylinder to 1.250 inside diameter for a nice piston fit.

I did make a rudimentary drawing of what it might look like.

Thanks for looking
Ray

 

[Rdean33422]

The picture shows the piston and two cylinder heads. The cylinder heads have an o-ring inside the extension part to seal the piston rod but still allow it to slide back and forth.


I have never done an internal o-ring groove before so i made a new tool.
It is just mild steel with about half the diameter milled off and a relief groove turned behind it.


It worked just fine once the height of the tool holder was adjusted.

Thanks for looking
Ray

 

[TonyM]

Looking forward to this one.

 

[Rdean33422]

Great to have you along Tony.
Much of this design is new to me so it will be a learning experience.

Ray

 

[JimSvarv]

Double acting engines exist for sure.
But I'm not sure how much it matter that a power stroke is at a compression stroke.
The power would be taken from the flywheel anyway.

It would be like a 180 degree crank inline twin which works for sure.

Your engine will be a bit like a hit and miss, maybe it runs a bit cooler with the gas cycling back and forth a bit.

Anyway always fun to see what you come up with!

Here is a kinda funny engine which is like the lower half of a double acting engine.
https://www.pattakon.com/pattakonPPE.htm

 

[Sprocket]

Ray,
I've been working on my interpretation of Phil Duclos' 6-cycle "Oddball". He used a 3:1 gear ratio and a long duration exhaust cam. The exhaust valve stays open for about 1/2 of the gear rotation, or 1-1/2 full crank rotations. It fires only every third rotation instead of every other.
It is a single cylinder, but I'm sure you can make it work for two with the side shaft fairly easily.
Also, for double acting cylinders, think of Doug Kelley's "Snow" engine. Your start looks a lot like half a "Snow". It is also a side shaft.
I enjoy your builds, can't believe how fast you work,
Doug