Increasing more and more the con-rod length, you finally get a harmonic or pure sinusoidal piston motion. Such a piston motion increases the constant volume portion of combustion and so increases the efficiency and the pick power at high revs. What actually the long rod makes is to keep the piston around TDC for more time. But the height of the engine would be enormous and the long con-rod would bend immediately.

The following slide explains the Pulling Rod Engine or PRE presented at www.pattakon.com web site, compared to conventional



here they are shown the internals of a four stroke PRE (the con-rod can move without hitting the piston and the cylinder, i.e. no need for oversquare design)



and here is a combact Junkers-PRE in section view (two stroke power concentration and at the same time four stroke lubrication, built-in scavenging pumps, four stroke like torque curve, through scavenging, improved efficiency due to the slow motion of the piston at TDC, etc). An electric power station based on this single cylinder Junkers-PRE is absolutely free from vibrations,making it ideal for Hybrid cars, Hybrid vehicles, autonomous robots etc.



In general, to see the relevant animations enter into the Pattakon PRE , click on an image to download the 'exe' file and then open it.



The conventional engine offers a sub-sinusoidal piston motion around TDC. This PRE engine offers an over-sinusoidal piston motion around TDC, i.e. it increases a lot the constant volume portion of combustion. The shorter the con-rod length, the longer the time the piston stays near TDC. The PRE engine can be overquare, square or undersquare.

In the plot below what you see is the piston travel versus the crank angle for a conventional engine, the PattakonPRE (both using conrod to stroke ratio equal to 1.65) and the Harmonic engine.




If the conventional is revving at 1.35 times SLOWER than the PRE (for instance the conventional is revving at 5600 rpm while the PRE is revving at 7500 rpm), then around TDC the working medium (air or mixture) cannot see any difference. The orange curve in plot below is (around TDC) identical to the blue curve of the PRE.



If the conventional is revving at 1,35 times FASTER than the PRE, then around BDC the working medium cannot see any difference again. The orange curve in the plot below is (around BDC) identical to the blue curve of the PRE.



So the PRE as regards TDC is nothing but a conventional revving at significantly slower revs, and as regards the BDC, the PRE is nothing but a conventional revving at significantly faster revs.

It is obvious that the valve lift profiles (if valves are used) have to be change to suit to the PRE piston motion, as well as the spark advance (or the injection advance in case of Diesel). If necessary, the PRE can use Pattakon’s Variable Valve Actuation (or VVA) system in order to optimize breathing along the whole rev range.



I’ll be glad to hear your objections and answer your questions.

Thanks
Manolis Pattakos

What is the volumetric efficiency of this? I must admit it looks pretty interesting..