Opposed Piston Diesel Engine
Half-baked idea.
I've been looking at Opposed-piston_engines and I'm interested in them, particularly the M4+2 This is my try at designing one.
A different approach: http://www.gizmag.com/duke-engines-axial/33631/ or this: https://www.youtube.com/watch?v=aZB0Go3Kj-k
Goals
The goal of the engine is to simplify design. With a focus on fewer parts and easier to fix. Because of CNC manufacturing, the solid parts can be complex and precise, so long as replacing them is simple.
Pistons
The pistons are opposed in a single chamber. I'd like to see if the pistons can be machined with enough precision to not need rings.
Even further in the half baked ideas would be to intentionally leave a very small gap (sub millimeter) to reduce friction. The pistons could be aligned either with air pressure or magnetism (particularly induction).
Timing Profile
I drew out the timing profile, and I think it's possible, though it's interesting.
The piston chamber has a opening at either end for intake and outlet, but no valves. There is a fuel injector closer to the intake side. P1 is the piston on the intake side and P2 is on the outlet side. Position I is the outside edge of the inlet, C is the center (and the point of combustion) and O is the far side of the outlet.
I think the piston cams will be wedged between two camshafts - one to push and one to pull.
Intake and Combustion
Intake begins with the pistons touching. P2 is driven by a cam linearly from I to C. When P2 is halfway through this motion, P1 beings moving, also linearly, but at twice the speed. The result being that P1 and P2 begin with no gap under the intake, a gap opens up, then closes towards the center. The fuel injector is timed to fire just after P1 closes the intake. The pistons come close enough to compress the air and begin diesel combustion.
The compression ration needs to be about 25:1.
It may also make sense to put the fuel injector just outside the intake and fire it just as P2 begins to move.
Expansion
At this point rather than the cam driving the pistons, the pistons switch over to deliver power. So the