HOT-GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES, NOT OTHERWISE PROVIDED FOR

Description

F02G covers positive-displacement engines powered by hot gases or combustion products, including Stirling engines, Ericsson engines, and related thermodynamic cycles that operate by expanding heated working fluids rather than traditional combustion-driven piston mechanisms. This subclass also encompasses systems for capturing and utilizing waste heat from combustion engines where such applications are not specifically covered elsewhere in the classification scheme. Technologies include heat exchangers, regenerators, and energy recovery systems integrated with engine plants. Adjacent classes F02B–F02F address conventional internal combustion engines, while F02G specifically focuses on alternative thermal cycles and waste-heat utilization not classified in specialized engine or heating sections.

Filing statistics

IPC subclass F02G recorded 9,170 patent applications worldwide between 2013 and 2023. Annual filings declined from 1,097 in 2013 to 404 in 2023 (-63%), peaking at 1,134 applications in 2016. The most active applicants in class F02 are TOYOTA MOTOR CORPORATION (8,687 applications), ROBERT BOSCH (8,328 applications) and FORD GLOBAL TECHNOLOGIES (7,423 applications).

Source: EPO PATSTAT, worldwide filings