Energy transfer machine

A machine comprising:

• an outer stator having inward-facing cavities;
• a carrier mounted within the outer stator for rotation within the outer stator about a first axis positioned substantially centrally with respect to the inward-facing cavities of the outer stator;
• an inner rotor mounted to the carrier for rotation about a second axis, the second axis moving with the carrier and being substantially parallel to the first axis and positioned eccentrically relative to the first axis, the position of the second axis relative to the first axis defining a crank angle;
• the inner rotor having outward-facing projections arranged to mesh with the inward-facing cavities of the outer stator to form primary chambers within the inward-facing cavities of the outer stator which have primary chamber seals which seal and unseal as the inner rotor rotates about the second axis and the carrier rotates about the first axis;
• the outward-facing projections and the inward-facing cavities being configured to form, after or at the same time as a sealing crank angle of a primary chamber of the primary chambers, a sub-chamber contact or near-contact seal extending across the primary chamber to form a first sub-chamber and a second sub-chamber of the primary chamber at a sub-chamber sealing crank angle, and the contact or near-contact seal unsealing at a sub-chamber unsealing crank angle before an unsealing crank angle of the primary chamber;
• a first sub-chamber geometric compression ratio being defined, before the sub-chamber sealing crank angle or after the sub-chamber unsealing crank angle, by a primary chamber geometric compression ratio relative to the sealing crank angle of the primary chamber, and the first sub-chamber geometric compression ratio being defined, between the sub-chamber sealing crank angle and the sub-chamber unsealing crank angle, by the primary chamber geometric compression ratio as of the sub-chamber sealing crank angle multiplied by a further geometric compression ratio of the first sub-chamber relative to the sub-chamber sealing crank angle, and a second sub-chamber geometric compression ratio being defined, before the sub-chamber sealing crank angle or after the sub-chamber unsealing crank angle, by the primary chamber geometric compression ratio, and the second sub-chamber geometric compression ratio being defined, between the sub-chamber sealing crank angle and the sub-chamber unsealing crank angle, by the primary geometric compression ratio as of the sub-chamber sealing crank angle multiplied by a further geometric compression ratio of the second sub-chamber relative to the sub-chamber sealing crank angle,
• the first sub-chamber geometric compression ratio reaching a maximum at a first sub-chamber minimum volume crank angle between the sub-chamber sealing crank angle and the unsealing crank angle of the primary chamber.