This landscape identifies 1,297 patent families filed or published between 2015 and mid-2026, drawn from title and abstract language naming vacuum pumps, dry screw vacuum pumps or liquid ring vacuum pumps combined with performance claim terms like ultimate pressure or corrosive gas handling. Because publication lags filing by roughly 18 months, the 2025 and 2026 counts understate true filing activity and will rise as more records publish. Treat the 2021 peak of 75 families as the clearest recent high point rather than the endpoint of the trend.

Rotary-piston pump mechanisms, classified under IPC group F04C, account for 980 of the 1,297 records in this corpus — more than double the 470 records under general positive-displacement pump classification F04B. This means screw-type and vane-type rotary mechanisms are the most heavily claimed segment of the field, and new filings there face the densest prior art. Smaller clusters under F01C, H01J, B01D and H02K show where pump mechanics intersect with adjacent fields like separation processes and motor design.

Filing activity peaked at 75 families in 2021, up from 42 in 2017, but had already fallen to 51 by the 2022 midpoint and continues to decline toward the present partial year. This pattern points to a maturing claim landscape rather than one still expanding, with core mechanical architectures largely staked out and newer filings likely concentrating on narrower performance or control claims. The apparent recent drop should be read partly as publication lag rather than a genuine stop.

China leads with 300 filings at its receiving office, ahead of the United States at 284, followed by the European Patent Office at 228, Japan at 127, WIPO PCT filings at 84 and the United Kingdom at 83. This ordering suggests that recent claim activity in ultimate-pressure and pumping-speed language is shifting toward the Chinese patent office, and freedom-to-operate reviews should weight China at least as heavily as the US going forward.

US4225288A, assigned to Siemens Aktiengesellschaft and granted in 1980, claims a pump set combining a compressor with a liquid ring vacuum pump, sized so a relatively small liquid ring pump can draw and hold vacuum under 40 Torr. It is a representative early example of staged compressor-plus-liquid-ring architecture rather than the most-cited patent in this corpus. Its relevance today is as a template: later claims on staged vacuum systems and ultimate-pressure control build directly on this compressor-matching approach, so designs using a similar staged configuration should check its claim scope and expiry status.

The comparatively thin filing density in condensable-vapor handling for dry screw pumps, corrosive-gas-resistant seal geometries, and motor-integrated multistage staging suggests these branches are less occupied than the core rotary-piston mechanism claims. Power-consumption control electronics specific to vacuum pumps also shows lighter coverage relative to the mechanical claim clusters. These are not guaranteed-clear areas, but they warrant a closer novelty search before assuming the space is as crowded as the core F04C claims.