Oscillating I.C. Engine

[gbritnell]

Brian,
I have never seen the Duclos engine so I don't know how it is configured but here's some 2 stroke information relative to what I see you have posted.
First off 2 cycle engines are ported (intake and exhaust). They receive the intake charge from a pressurized crankcase through porting. Once the charge has been ignited and burned it exits through cylinder porting that it higher than the intake transfer ports.
On you engine it looks like the carb is feeding directly into the combustion chamber. I don't understand how this can work. The biggest reason being as the engine needs to take it's charge on the downstroke every cycle. The second thing is where is your exhaust porting?
I'm not trying to throw a wrench in you design but I would like more information on how this engine cycles. (fire, exhaust, intake, compression, fire)
gbritnell

[Jasonb]

George, its a 4-stroke.

Fires with both valves shut, as the piston comes back up the exhaust is opened by the usual cam arrangement, as the piston goes back down the inlet valve is opened by the vacuum as its an atmospheric valve, valve closes and mixture is compressed as the piston comes back up and then you start all over again.

The carb feeds through the inlet valve into the box on the side which is best described as the head rather than straight into the combustion chamber proper.

This is the one from the Monitor, think of the block as a cylinder head, inlet valve at the top, exhaust at teh bottom plug on the left in this case and the small hole on the right is where it joins the combustion chamber rather than the usual whole dia of the bore

[gbritnell]

Ok, I see now! How is the exhaust valve operated. By that I mean how does the pushrod come from the cam to the valve with the cylinder oscillating?
gbritnell

[jschoenly]

Cool design!  Judging by the valve cage placement, I'm assuming the valves are stationary, only the cylinder is doing the moving/oscillating.  Fun stuff!

[Jasonb]

Thats it only the cylinder moves the "valve block" is solid to the green support so can be linked up like any other hit & miss

[BillTodd]

Brian

ATM you have a face seal on the cylinder valve box interface which means it has to take the full combustion pressure and slide.

 I wonder if you'd be better off with an external ring seal? (Something like a couple of piston rings) 

Bill

[Jasonb]

The Duclos original design just used the single O ring and that seemed to work.

Also as Brian has a liking for using O rings as piston rings he is in effect using a piston ring to seal things

[Brian Rupnow]

Hang on boys, I'm modelling as fast as I can!!! Wife and I had to drive to Hamilton this morning to welcome my newest grandchild, Benjamin--8 pounds 7 ounces born at 6:30 this morning.--Mom and baby are doing well---Ben looks just like me--No hair and no teeth!!! This engine is a four cycle. The carburetor is attached solidly to the dark green cylinder support stanchion, which does not move. Strange as it may seem, the valves are both mounted in the same block that holds the carburetor, so the valves don't move either. There is a cam lobe on the far side of the red gear, setting in a cut out area in the pale green crankshaft support and the "pinkish/purplish" rectangular part with the round dark blue pin in it is the exhaust valve pushrod. That round dark blue pin is the "exhaust valve lockout latch" that the "hit and miss lever" catches on to send the engine into "miss" mode.---More to come!!!---Brian

[b.lindsey]

Congrats on the new grandbaby Brian...glad to hear everyone is doing well too!!

Bill

[Brian Rupnow]

The modelling is completed for this engine, except for riser blocks under the baseplate so the flywheel doesn't hit the bench-top. NOW---This is the point at which I may do something really crazy!!! Remember how, in another thread I asked about an offset, gear driven flywheel. You will see that even if this flywheel did have "deflector blades" soldered into the lightening holes in the flywheel web, to create a fan effect, the air wouldn't blow on the cylinder where I want it to. Now--If I extended that crankshaft support block closest to the flywheel about 2 1/2" horizontally, moved the flywheel over the same amount and mounted it on a stub shaft attached to the crankshaft support block, and popped a couple of 2.5" o.d. spur gears in there, the flywheel would be right where I need it to be.  One gear mounted on the end of the crankshaft and one mounted on the flywheel--the fan effect from the flywheel would blow directly over the cylinder fins. If it didn't work, I can replace the extended crankshaft support with one similar to what is shown in the model, move the flywheel back, and remove the gears. All I would be "out of pocket" for would be a couple of purchased hardened gears. (I could even make the gears myself for that matter.)---Whatcha think???

[Jasonb]

If you do that don't forget to redraw the cylinder and head fins at 90deg so the air blows through them for maximum effect.

Think I would mount the crankshaft gear inboard of teh support between the governor bracket, glywheel may even fit close to the carb rather than stuck right out the side.

[Brian Rupnow]

Jason----Since this will be a hit and miss engine, and will be drawing ambient room temperature air in and out of the cylinder during all of the "miss" cycles, it won't get very hot anyways. I just want the air around the fins to move a bit. It's a kind of "Any air movement is better than no air movement at all" kind of thing.

[Heffalump]

Best to think about which looks prettiest in that case Brian 

[Allen Smithee]

If you bored radial holes in the rim of the flywheel and then cowled it you could duct the air centrifugally expelled from the flywheel around to the vicinity of the head fins. You'd only get a mild draft at these speeds, but it would meet the "some air is better than no air" principle. You could get a similar effect by attaching angled vanes to the side(s) of the flywheel and then cowling the region of the vanes, so that air is drawn in at the centre.

Or if you just want "different" you could make the piston rod drive a rocker and then a connecting rod so that the crankshaft itself could be relocated to the same place you want your geared setup to put it, but without the risk of torsional vibration & resonances from the gear backlash.

Failing that you could just install a woman next to the cylinder head because my wife assures me that a woman will always bring a breath of fresh air to any overheated situation. If increased cooling is needed you just ask the woman if she's putting on weight - this will instantly drop the temperature by 30-40 degrees (a technique I use to save on aircon running costs at home on hot summer days).

£0.09 supplied,

AS

[Jasonb]

Having just built the 1/2 scale Gade I'd say no air is quite good enough

Thats air cooled and does not get very hot.

Suppose its a toss up between the engine having to work harder due to the extra friction and drag from the gears, shafts and fan which will make it run hotter and the cooling effect the fan will give