Rotary Engine 101: Mechanics
Hopefully you have already checked out some of the animations. If so, you will be familiar with the odd motion the rotor makes in the housing that somehow keeps all the apex seals on the trochoid surface at one time while each working chamber changes volume. It may seem miraculous, but really it is simple math, er...calculus and trig. Anyway, it's really not that hard to understand on a visual basis, so let's take that approach.
[397K Animated GIF]
The seemingly complex motion of the rotor is actually the combination of two simple motions: Rotation and Orbit. The rotor rotates on its bearing, which mates to the eccentric shaft journal. The orbit is introduced by the eccentric shaft which, itself, is merely rotating, but with the journal offset from its center. Riding on the journal, the entire rotor is caused to orbit the eccentric shaft, irrespective of its own rotation. The real magic, however, is synchronizing the two motions so as to achieve the desired results, which is planetary motion (rotation and orbit).

Please be patient while animations load. Each animated GIF is approximately 400K

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Simple Rotation
[391K Animated GIF]
Simple Orbit
[398K Animated GIF]
Planetary Motion
[389K Animated GIF]
Copyright © 2001 by Blake Qualley. All Rights Reserved.