A rotational engine system comprises a rotational engine and a propulsion system. The rotational engine includes an outer ring enclosure, an inner ring component, and a drive gear. The inner ring component includes a piston and a drive gear engagement portion. The piston is configured to travel within the outer ring enclosure along a circumference of the outer ring enclosure. The drive gear engagement portion is configured to rotate as the piston travels along the circumference of the circular shape of the outer ring enclosure. The drive gear is coupled to the drive gear engagement portion of the inner ring component such that rotation of the drive gear engagement portion rotationally drives the drive gear. The propulsion system is configured to deliver propulsive energy to propel the piston along the circumference of the outer ring enclosure.

A rotary internal combustion engine with a housing having a fluid passage defined therethrough opening into a portion of its inner surface engaging each peripheral or apex seal of the rotor. An injector has an inlet for fluid communication with a pressurized lubricant source and a selectively openable and closable outlet in fluid communication with the fluid passage for delivering the pressurized lubricant to each seal through the fluid passage. A housing for a Wankel engine and a method of lubricating peripheral seals of a rotor in an internal combustion engine are also discussed.

A rotary internal combustion engine with a housing having a fluid passage defined therethrough opening into a portion of its inner surface engaging each peripheral or apex seal of the rotor. An injector has an inlet for fluid communication with a pressurized lubricant source and a selectively openable and closable outlet in fluid communication with the fluid passage for delivering the pressurized lubricant to each seal through the fluid passage. A housing for a Wankel engine and a method of lubricating peripheral seals of a rotor in an internal combustion engine are also discussed.

Pressure changing devices and methods of making and using the same are disclosed. One pressure changing device includes an elliptic cylinder and a piston that has an external surface with a trochoid cross-section. Another pressure changing device includes a piston and a rotating cylinder that has an internal surface with a trochoid cross-section. Another pressure changing device includes two fixed axes, one for rotation of one component and another for orbiting or oscillation of the other component. The devices and methods include stacked pressure changing devices with one or more common shafts. The pressure changing device may be easier and less expensive to manufacture and repair than prior pressure changing devices of the same or similar functionality, and can provide efficient gap sealing in a high-pressure expansion part of a compression or expansion cycle.

A rotary internal combustion engine includes an arcuate compression chamber, an arcuate expansion chamber, an output shaft, and a piston coupled to the output shaft for movement through the arcuate compression chamber and the arcuate expansion chamber. The piston has a leading end, a trailing end, an inlet valve that is located at the leading end of the piston for receiving a compressible fluid from the compression chamber and an outlet valve that is located at the trailing end of the piston for expelling a combustion gas into the arcuate expansion chamber.

A rotary internal combustion engine includes an arcuate compression chamber, an arcuate expansion chamber, an output shaft, and a piston coupled to the output shaft for movement through the arcuate compression chamber and the arcuate expansion chamber. The piston has a leading end, a trailing end, an inlet valve that is located at the leading end of the piston for receiving a compressible fluid from the compression chamber and an outlet valve that is located at the trailing end of the piston for expelling a combustion gas into the arcuate expansion chamber.

A rotary engine has a rotor with a rotor pocket for receiving air-fuel mixture that is combusted therein to propel the rotor within the housing. The rotary engine may have one or more intake spray injectors that spray fuel into the rotor pocket and onto the rotor face within the intake chamber to effectively cool the rotor pocket and rotor face. An air channel extension of the rotor pocket may be configured in the housing and/or in the rotor to extend from the compression chamber into the ignition-combustion chamber to relieve some pressure in the trailing compression chamber of a rotor face to minimize negative work. A supplemental air-fuel conduit may be configured to supply high-pressure gas from the compression chamber to an ignition injector(s). A thrust nozzle may be configured within the rotor pocket to direct combustion gases therethrough to propel the rotor and increase efficiency.

Aircraft power plants including combustion engines, and associated methods for recuperating waste heat from such aircraft power plants are described. A method includes transferring the heat rejected by the internal combustion engine to supercritical CO.sub.2 (sCO.sub.2) used as a working fluid in a heat engine. The heat engine converts at least some the heat transferred to the sCO.sub.2 to mechanical energy to perform useful work onboard the aircraft.

A compound engine assembly including an air conduit having an inlet in fluid communication with ambient air around the compound engine assembly, a compressor having an inlet in fluid communication with the air conduit, an engine core including at least one rotary internal combustion engine and having an inlet in fluid communication with an outlet of the compressor, a turbine section having an inlet in fluid communication with an outlet of the engine core and configured to compound power with the engine core; and at least one heat exchanger in fluid communication with the air conduit, each heat exchanger configured to circulate a fluid of the engine assembly in heat exchange relationship with an airflow from the air conduit circulating therethrough. A method of supplying air to a compound engine assembly is also discussed.

An oblong-shaped rotor engine with improved high sealing performance includes an upper end cover, a lower end cover, a rotor, three combustion chambers, three isolation zones, a fuel spray ignition unit, a sealing pin row and an eccentric driving shaft, a sealing pin row, which seals the transition zone between different combustion cylinders, wherein the engine according to this invention can better avoid the effect of structural wear, effectively enhance the sealing performance between combustion chambers and abate gas leakage between cylinders, wherein the designed profile and sealing means can enlarge the design error margin for engines, abate the processing difficulty of engines, and effectively decrease the production costs of engines.