Two concentric Cardan joints interconnect an inclined power shaft (blue) with two rotors (red, green). As the power shaft rotates with constant angular velocity, the rotors rotate with variable and different angular velocities.
Pistons (gray) secured on the rotors orbit about the toroidal cavity axis, approaching and moving away from each other two times per power shaft rotation (cat and mouse motion).
Four independent chambers into the toroidal cavity are formed.
The displacement of a chamber versus the power shaft angle is shown at the following plot:
while the pure sinusoidal curve (blue) is added for comparison.
The following plot (click to enlarge) gives the angle, the angular velocity and the kinetic energy of each rotor versus the power shaft angle, for constant angular velocity of the power shaft.
The black curve is the displacement of a chamber.
The green curve is the total kinetic energy of the two rotors.
Some of the advantages of the toroidal engine: simplicity, riddance of valves, perfect four-cycle aspiration, efficient combustion chamber, lightweight and compact structure etc.
Its Achilles' heel has always been the mechanism interconnecting the rotating / oscillating pistons to the power shaft.
For equal piston diameters, the torque on the crankshaft of the conventional engine is way lower as compared to the torque on each rotor shaft of the toroidal rotary engine. This is because of the long, and constant, eccentricity of the piston of the toroidal rotary engine, making crucial the use of massive and robust "mechanism" between the power shaft and the rotor shafts.
Here, the two concentric Cardan joints that interconnect the power shaft with the two rotors, are disposed out and at the one side of the toroidal cavity, so that the toroidal cavity poses no limits on their dimensions and strength, while the casing needs be strong only at the one side of the toroidal cavity.
Here the "motion converting mechanism" comprises nothing else than the two concentric Cardan joints, i.e. besides the power shaft and the two rotors (with their pistons), all it takes is two yokes (or crosses):
The angular displacement of the toroidal cavity about the center of the concentric Cardan joints varies continuously the compression ratio and the displacement of the engine, as shown in the following drawing, which is not stereoscopic. At left the engine has higher compression ratio:
In the case of a pump (with two intake ports 180 degrees apart, and two discharge ports, also 180 degrees apart) there is the option of feeding two independent circuits by the same pump, like the heart does.
There is also the option of continuously variable capacity from zero to a maximum: the toroidal cavity of the pump is angularly displaceable about the center of the two concentric Cardan joints. Used as the oil pump of an engine, it can control the oil pressure by controlling its own capacity, avoiding the relief valve and the energy lost there.
Rotary Portable Flyer
The two shafts counter-rotate in synchronization to each other without additional synchronizing means.
The two shafts / propellers are driven directly by the same combustion forces.
The loads on the bearings of the rotor-pistons and the inertia vibrations are substantially reduced as compared to the single power-shaft-rotary.
The glow plug "sees" each of the four combustion chambers the right moment (a spark-plug / high voltage circuit is optional).
With four combustions per rotation, easier starting and higher power to weight ratio, it competes the OPRE Portable Flyer.
While in the reciprocating engine the location and the size of the intake valves / ports are limited, in the rotary engine they are not, enabling any Miller cycle like Mazda's SkyActive, Nissan's DIG-S, Toyota's PRIUS.
With a simple control over the intake port (widely variable intake port closing), the rotary can achieve the unlimited-Miller-cycles of the PatAir and most of the MultiAir modes of the PatAir.
Click on any image below to download the relevant animation (first check the size).
After opening the animation (7.3MB) press the . key of the keyboard to enter in "step-by-step" mode. Press a few times the . key
to move the piston to a TDC and then press (or keep pressed) the Space Bar key to control the compression ratio (for simplicity it is shown displaceable the power shaft and not the toroidal casing). Press ,
key to get back to "animation" mode. Move the mouse above the animation to change the rhythm. Double click the mouse, or
press ESC key, to quit the animation.
The complete engine from various viewpoints (2.3MB).
To see stereoscopically is easy, stunning and useful.
For more about stereoscopy click Stereoscopy .
The stereoscopic representation shows many, otherwise invisible, details.
And there is always the option to concentrate on one only image (6.3MB).
The rotary engine mechanism from various viewpoints (3.9MB).
The principle (two concentric Cardan joints), stereoscopically. The power shaft is the green, the one rotor is secured to the cyan part, the other rotor is secured to the blue part (2.0MB).
Rotary Portable Flyer, controllable windows exe animation (2.3 MB).