Great video, thanks for explaining! I found my way here trying to understand Alfadan's large displacement, inline four engine they are developing. Seems the traditional connecting rods have been replaced by some proprietary Scotch yoke. Paired up with the cylinder head being valveless, this engine sounds promising!
I have Master Degree in political science... But I'm intereted in physics and electeonics stuff... Right now I'm starting my on home school in physics and electronics. Your video is helpful and inspiring.. Thank you very much..
What is the point vs. a standard engine crankshaft mechanism? To avoid the sideways pulling force on the piston? But it is replaced with sliding friction between the pin and the slot.
Also I noticed you use plastic tubing over the cam rod. Do you have to do that? I have not seen that on wooden models.Thanks! This is the best video on making one!
Probably to reduce wear on the surfaces sliding on each other. It may also reduce the clicking noise when the pin breaks contact with one side of the cam rod and makes contact with the other side when changing the direction of the linear movement.
The scotch yoke is not found in regular combustion engines. There is only one from the 1940´s which was never build because it had all sorts of problems, but no modern engine uses this mechanism.
1. No movement/inertia of the linear moving parts in any other direction, so less stress when reversing direction. 2. The linear output is purely sinusoidal-the piston exactly follows the pin on the wheel, whereas with a crank the distance between the pin rotating on the wheel and the piston varies due to the varying angle of the connecting rod (from 0° when the pin/piston is at TDC & BDC up to a maximum angle at 90° away). This results in a lower linear acceleration of the piston when moving away from TDC/BDC until mid-stroke, and then higher acceleration from mid-stroke until the end of the stroke (the higher and lower being relative to the acceleration of the pin on the rotating wheel in that direction). Thus a crank distorts the linear motion output so it is not purely sinusoidal. The shorter the connecting rod relative to the offset of the crank (i.e. the wheel radius) the more the distortion.
The motion of the piston here is exactly sinusoidal. Does anyone know how far off the motion would be from a sine with a tilting piston rod like all engines and compressors use? (well at least those that use a reciprocating piston)
Saudações LS Ludic Science. Saudações a todos. Mecanismos simples e curioso. Converte o movimento circular em linear no embolo. O oposto também é possível. Realmente interessante. Tudo de bom.
Like a reciprocating engine, it would require a flywheel for momentum so it wouldn't get stuck at top dead center or bottom dead center. Would also require initial rotary motion applied to the wheel when starting, as linear force applied when the rotating pin is at TDC or BDC would present a simple shear force on the pin and would not cause it to rotate. Alternatively, a second piston/cylinder arrangement in parallel operation but offset so both pistons are not at TDC or BDC at the same time.
