Engine technologies and innovations..

[Zico]

After the V-power thread I thought it would be interesting to discuss the many various technologies and ideas/innovations for the IC engine. So I'll start the ball rolling with..

The Rand cam engine.. Radmax Rotary- http://www.regtech.com/

Design

The engine functions by using two opposing and identical disc-shaped rotors that are offset by 90 degrees around the central shaft. These rotors have a sinusoidal side profile with two "bumps" and two "valleys". Both rotors turn in the same direction within the housing and are separated by a central section. Inlaid in this central section are 12 vanes that can slide between one or the other rotor housing but do not turn with the engine's rotation. Since both rotors are offset and opposed, the straight-line distance between the two rotors is always the same. This allows for the vanes to move from one side to the other without breaking. The rotors are also called Cams, due to the camming action they use to move the vanes.

As opposed to a w*nkel engine, which has a moving combustion chamber, the rand-cam engine's combustion chamber is fixed due to the stationary nature of the vanes, yet varies in size due to the rotor's motion.



Advantages

The advantage of the rand-cam engine is its compactness and power output. Whereas a 4-cycle piston engine's piston only fires once every other turn of the crankshaft, and a w*nkel engine fires once every turn of the e-shaft, a Rand-cam engine fires 24 times per revolution of its main shaft. It can also achieve high compression ratios for diesel operation.


Current status

The engine is currently under development by the US based company Regi U.S., Inc and has reportedly reached the prototype stage. According to their published information, the prototype will deliver 42 bhp from a unit only 6 inches wide by 6 inches long and can run on Ethanol, Natural Gas, Diesel, LPG (Propane) and Hydrogen. There are immediate plans to demonstrate the engine. The first intended users are military contractors.


Im struggling to understand or visualise the cycle with this... but the 6 x 6 inches prototype produces 42 bhp !! Impressive stuff..

Edit- visualisation here.. http://www.regtech.com/Radmax_Technology/

and prototype pics here.. http://www.regtech.com/Radmax_Technology/Prototype_Engine/

[airshifter]

It looks as though it would be a nightmare to keep the system sealed. Essentially the combustion chamber is moving on one axis, and the intake and exhaust ports move on another axis.

It does seem it would make very good use of space. There are constant cycles of every stroke in the combustion process of a 4 cycle engine taking place.

I'm rather confused how lubrication of the moving parts would take place, as the seal to the upper and lower cams is exposed to the combustion chamber, since it really is the combustion chamber.

[Magnus]

Since SAABs efforts to construct an engine with a variable compression system through tilting the head, I would like to mention that this is the idea of Per Gillbrandt at SAAB. He has been theyre in-house genious for many years now, all though I think he is about to/recently retired.
The engine though posed bigger problems then anticipated and I think the development is put on hold for now.

[airshifter]

I remember reading about the variable compression engine, and thinking from the start it was a rather complex way to do things. I thought of several different ways that from a casual point of view seemed to be less complex, and wondered why engineers with more ability couldn't find a simpler way.

One of the ways that came to mind was simply adding a moving part to the cylinder head that sealed like a piston. Picture the way an intake or exhaust valve works, but make is a sealed protrusion in the way a piston seals with rings. This could be shaped in a way that fits within the limits of the cylinder head space, as it wouldn't have to be round. It could be actuated with a cam or servo motor, since it wouldn't be a constant or instantaneous need device.

Granted it wouldn't be a simple task, as cylinder head and piston design would have to allow for clearance while keeping a suitable combustion chamber shape. With todays technology activating and sealing it wouldn't be difficult though. It just seemed to me it would still be way easier and cheaper to produce than an engine that hinges.

The second quick idea was simply having the crankshaft rise or drop. Though again not a simple task, it still seemed to be less complex than the hinge thing.