Trochilics the science of rotating mechanical devices aptly describes the Quad cycle engine. Its rotating piston has wide areas of practical application. They range from Stirling cycle, internal combustion, to high-pressure gas or steam and with adaptive alterations to gaseous or fluid pumping.

The piston is composed of two mirror image gull wing segments intermeshed and rotating about a common central axis. Varying the relative segment velocities in rotation, forms four variable quadrants. The quadrants are functionally a four-cylinder engine requiring no mechanically driven valves. Each segment is integrally connected to a rotating gear cage that converts the undulating piston motion to a liner rotating output shaft. The segmented piston has a preferred direction of rotation imposed by the mechanically leveraged action of the gear cage.

Intake of a working gas or combustible mixture is initiated by a quadrant expanding as it passes the intake port drawing in the working fluid. The gas is compressed and transported to a heated expansion cavity in the Stirling engine or ignited in the internal combustion engine. Expanding gasses vector the quadrant through its power phase that ends when exposed to an exhaust port, followed by a decreasing volume exhausting the expended gas.

All four quadrants operate in a like manner providing a continuous power stroke through the entire 360°of rotation. This gives a power to weight advantage in the mock four-cylinder trochilic design. Engine efficiency can be enhanced by the addition of a trochilic expansion stage or pre-stage compression piston.

In reciprocating engines, the flywheel kinetic energy is used to counter piston direction change, but maintenance of that energy comes at the expense of total energy out put of the engine. With the trochilic piston, the delta in mass velocity of the primary piston segment is equal and opposite that of the secondary segment. Direct transfer of kinetic energy from one segment to the other result in near zero energy loss from piston velocity changes. Also, note that it takes two revolutions in four-cycle reciprocating engines to extract energy for a given displacement whereas the Trochilic engine takes only one.

Trochilic Quad cycle engines do not employ compression rings, as conventional engines. This design approach improves efficiency through the reduction of friction losses and reduced engine wear. Piston to cylinder clearance must however be held to very close tolerances. A simple method for adjusting and maintaining piston to cylinder wall spacing is employed. The sidewalls can be positioned to within the practical limits imposed by surface irregularities and thermal expansion. Ablative ceramics provides minimum clearance at its nominal operating temperature. Proprietary technology, not discussed in this forum, keep internal component temperatures much lower than might be expected limiting the difficulties of thermal expansion.

A benefit of the trochilic design is no loading between piston and cylinder walls. In the absence of contact friction, lubrication is not required as in previous engines. The piston and expansion stresses are borne by the main end bearings not by piston to cylinder contact.

With a solar collector, the hybrid Trochilic engine can supply power to the power grid for financial benefit as well as for direct consumption. The unusual nature of this engine allows its use in the open cycle, requiring no recycling gas heat exchanger. At times of insufficient solar activity, for the power required, the open cycle hybrid Trochilic engine can function from a dual energy source. That is, the engine can run on internal combustion to whatever level required to assist the solar function to the desired power out put level. This also puts the need for battery back up and storage into an area of special requirements.