A hydraulic Trangine consists of a combustion or power piston in a conventional cylinder with a conventional four-stroke-cycle head and poppet valves operatable by a conventional camshaft, but driving a hydraulic piston instead of a crank. The hydraulic piston is in a circuit with a pair of phase-adjustable hydraulic pistons, each driving a separate crank, but with the two cranks connected by a differential that controls the phasing. Phase control alters the flow capacity of the hydraulic system and is the means whereby the stroke of the conventional combustion piston is adjusted to meet instantaneous load demands. Compression ratio of the combustion cylinder is simultaneously optimized by appropriate movement of a fourth hydraulic piston in the same circuit thereby controlling the volume of the hydraulic system, forcing the combustion piston to either move up, increasing the compression ratio, or down, decreasing the compression ratio. As an automotive powertrain, acceleration requirements are met by increasing the displacement of the combustion cylinder instead of by increasing its firing frequency. An analogous mechanical Trangine can also be constructed but is more difficult to describe verbally. However, both mechanical and hydraulic types of Trangine powertrains are included herein, along with their modes of operation. Either type is shown to possess the attributes of a reciprocating internal combustion-engine/infinitely-variable-transmission combination, as well as a means for limiting the maximum combustion chamber pressure.
For the hydraulic Trangine, the inherent capability for regenerative braking is described for Trangines having multiple combustion chambers. Hydraulic transmission efficiency is evaluated and related to the clearance between the piston and cylinder. Application of the Trangine concept to specific combustion processes, e.g., HCCI (Homogeneous-Charge Compression-Ignition), is also described.