Sealing in rotary positive displacement machines based on trochoidal geometry that comprise a helical rotor that undergoes planetary motion within a helical stator is described. Seals can be mounted on the rotor, the stator, or both. The rotor can have a hypotrochoidal cross-section, with the corresponding stator cavity profile being the outer envelope of the rotor as it undergoes planetary motion, or the stator cavity can have an epitrochoidal cross-section with the corresponding rotor profile being the inner envelope of the trochoid as it undergoes planetary motion. In some embodiments, the geometry is offset in a manner that provides advantages with respect to sealing in the rotary machine. In multi-stage embodiments, the rotor-stator geometry remains substantially constant or varies along the axis of the rotary machine.

A positive displacement rotary motion device including in one example a pulse detonation device. Also; an indexing system for a rotor assembly where in one example the indexing system regulates the rotational location of drive rotors. In one example the rotors are configured to rotate about a shaft.

A positive displacement rotary motion device including in one example a pulse detonation device. Also; an indexing system for a rotor assembly where in one example the indexing system regulates the rotational location of drive rotors. In one example the rotors are configured to rotate about a shaft.

A spherical compressor is provided. A cylinder body and a cylinder head are combined to form a spherical inner cavity. A sliding chute swinging mechanism is arranged between a piston shaft and a piston shaft hole or between a turntable shaft and a turntable shaft hole. The turntable shaft is driven to rotate so that a piston swings along a sliding chute relative to the axis of the piston shaft hole, or a turntable swings along the sliding chute relative to the axis of the turntable shaft hole, so as to form a V1 working chamber and a V2 working chamber with alternatively variable volumes in the spherical inner cavity.

A spherical compressor is provided. A cylinder body and a cylinder head are combined to form a spherical inner cavity. A sliding chute swinging mechanism is arranged between a piston shaft and a piston shaft hole or between a turntable shaft and a turntable shaft hole. The turntable shaft is driven to rotate so that a piston swings along a sliding chute relative to the axis of the piston shaft hole, or a turntable swings along the sliding chute relative to the axis of the turntable shaft hole, so as to form a V1 working chamber and a V2 working chamber with alternatively variable volumes in the spherical inner cavity.

The invention provides a pump comprising a pump inlet, a pump outlet, at least two threaded rotors and a pressure controlled valve, the pressure controlled valve being capable of controlling re-circulation of fluid from the pump outlet to the pump inlet. The pressure controlled valve can be a control valve. The invention also provides a multiple stage pump assembly comprising at least two pumps arranged in series, wherein at least one of the pumps is the aforementioned pump.

The invention provides a pump comprising a pump inlet, a pump outlet, at least two threaded rotors and a pressure controlled valve, the pressure controlled valve being capable of controlling re-circulation of fluid from the pump outlet to the pump inlet. The pressure controlled valve can be a control valve. The invention also provides a multiple stage pump assembly comprising at least two pumps arranged in series, wherein at least one of the pumps is the aforementioned pump.

Sealing in rotary positive displacement machines based on trochoidal geometry that comprise a helical rotor that undergoes planetary motion within a helical stator is described. Seals can be mounted on the rotor, the stator, or both. The rotor can have a hypotrochoidal cross-section, with the corresponding stator cavity profile being the outer envelope of the rotor as it undergoes planetary motion, or the stator cavity can have an epitrochoidal cross-section with the corresponding rotor profile being the inner envelope of the trochoid as it undergoes planetary motion. In some embodiments, the geometry is offset in a manner that provides advantages with respect to sealing in the rotary machine. In multi-stage embodiments, the rotor-stator geometry remains substantially constant or varies along the axis of the rotary machine.

Sealing in rotary positive displacement machines based on trochoidal geometry that comprise a helical rotor that undergoes planetary motion within a helical stator is described. Seals can be mounted on the rotor, the stator, or both. The rotor can have a hypotrochoidal cross-section, with the corresponding stator cavity profile being the outer envelope of the rotor as it undergoes planetary motion, or the stator cavity can have an epitrochoidal cross-section with the corresponding rotor profile being the inner envelope of the trochoid as it undergoes planetary motion. In some embodiments, the geometry is offset in a manner that provides advantages with respect to sealing in the rotary machine. In multi-stage embodiments, the rotor-stator geometry remains substantially constant or varies along the axis of the rotary machine.

An air compressor system useful for supplying a stream of compressed air for an end user is disclosed which includes a refrigerated dryer useful to remove moisture and harvest it from the compressed air. The refrigerated dryer includes an evaporator and a condenser, where the evaporator is useful to produce the moisture from the compressed air. The air compressor system includes an expansion tank which collects the harvested moisture from the evaporator. The expansion tank can include a low liquid level sensor useful to determine a low liquid level of condensate in the expansion tank. The low liquid level sensor can produce a signal indicating a low level of condensate which can be used to shut off a pump that pulls water from the expansion tank and provides it to the condenser of the refrigerated dryer.