Wolfgang
The Mazda rotary engine has a eccentric shaft with a .591” throw. The combustion pressures on the surfaces of the rotor are applied against this small crank to produce torque. The first third of the combustion is applied against the top dead center as the shaft moves with the rotor. The second third produces torque against the crank. The last third is not used as the exhaust port is exposed. Incidentally the last third is the most potent as the crank has just reached the three o’clock position.
The reason they do not use the last third of a stroke is because they have not figured out how to get separation from the intake stroke. When the port is moved ahead the exhaust has the freedom to go around the apex seal when it crosses the port and apply pressure to the intake manifold and fill the cavity.
When I mentioned the reed type exhaust in an earlier post I failed to say that they should also be designed to be a one way valve to function successfully.
Regardless I find that the use of a crankshaft with slightly over a one half inch throw is absurd. The damage to gear systems that I designed prototyped and tested confirm that the potential torque of a direct drive from the rotor is substantial.
I have a ball bearing inserted at the front of the rotor making the connection between the rotor and a machined down e-shaft. The front of the engine is stock. The center of the rotor spins in a true circle cone about seven degrees from a cut off drive shaft 5 ˝ “ from the bearing.
I am currently using a five sided connection but I realize that this is not as good as a triangle.
The connection consists of a round plate with a triangle milled (with its sides at right angle) in the center. This plate is welded in the rotor just behind the bearing. The back of the e-shaft is cut leaving only one half inch of the lobe. A triangle is then milled in the center of the shaft.
A shaft 5 ˝” long is then machined with triangle ends that taper seven degrees.
The engine is assembled with the shaft making the connection between the rotor and the exit shaft. If everything is tight it will turn smoothly. .
Cheers
Ken  |