The present invention features a hot air engine system designed to improve the overall efficiency of the engine. The engine features a mechanism for oscillating a piston cylinder such that the pivot point is at the bottom of the cylinder. This mechanism improves the overall efficiency of the engine by reducing the side forces that are produced when the back and forth motion of a piston is converted into rotational movement. To achieve this mechanism, a set of arms is attached to the piston cylinder and extend into the displacer chamber and are attached to the displacer. When the displacer oscillates during operation of the engine, the arms swing, and the cylinder rod swings in line with the arms, causing the cylinder rod to pivot at the bottom of the cylinder. This engine system runs on almost boiling water and can use industrial wastewater as a fuel source.

A hydraulic system employing an electronically commutated fluid working machine having working chambers, each having one or more electronically controllable valves actively controlled by a controller to regulate the net displacement of working fluid into or out of low- and high-pressure manifolds on a cycle by cycle basis to meet an indicated demand. The high-pressure manifold has an additional outlet, regulated by a controllable outlet valve. If the demand indicated by a demand signal is expected to cause pulsatile flow or vibrations which may excite resonant modes, the controller causes the displacement of working fluid by the working chambers to exceed the demand indicated by the demand signal, and the controller simultaneously opens an electronically controllable outlet valve to allow some of the excess flow to leave, such that the net displacement of fluid meets the demanded displacement of fluid, while mitigating the pulsatile flow or undesirable vibrations.

Highly efficient pressure differential rotary engines can include rotatable cylinders arranged radially around a central stationary shaft. Each of the cylinders can house one or more pistons, and the cylinders and pistons can rotate together about the central stationary shaft. Pressure differentials within the cylinders can be used to power the rotation of the cylinders about the central stationary shaft.

An improved sealing system for a poppet valve rotating sleeve internal combustion engine with rotating liners. A hydrodynamic face seal assembly includes a spring pre-load assembly provides a uniform loading to a primary sealing ring. A secondary seal is provided between the primary sealing ring and the cylinder head. Hydrodynamic face seal features are provided either on the mating face of the primary sealing ring or on the annular face of the rotating liner. The hydrodynamic face seal features include an inner sealing zone, and an outer loading zone with a plurality of hydrodynamic lift pads, and dam features which create converging surfaces. A lubricant is provided to the annular face of the rotating liner, so that a lubricant layer can be maintained between the primary sealing ring mating face and the rotating liner.

A rotating liner driving mechanism for converting existing engines castings to a rotating liner configuration (RLE) with minor changes to the engine or casting. A pulley is connected to the main accessory belt in the front of the engine and drives a shaft parallel to the crankshaft but external to the engine. Via a 90 degree gearbox, the driving rotation is turned about normal to the crankshaft and block deck face. This shaft drives a driving gear through a gear cover, which then drives one of the liners. Gears in the liner flanges propagate the rotation to all liners. An inline engine needs only one set of pulleys and driving mechanisms, but a V-engine may require two, one for each bank of cylinders. The driving pulley can have mechanisms included so that the gear ratio between crankshaft and rotating liners can be varied during engine operation.

Highly efficient pressure differential rotary engines can include rotatable cylinders arranged radially around a central stationary shaft. Each of the cylinders can house one or more pistons, and the cylinders and pistons can rotate together about the central stationary shaft. Pressure differentials within the cylinders can be used to power the rotation of the cylinders about the central stationary shaft.