Filing activity in this corpus concentrates among a handful of established compressor and HVAC manufacturers, including Daikin, Hitachi, Mitsubishi Electric and Mayekawa, alongside foundational US filings from firms like Trane. Rather than naming a single leader, the useful takeaway is that the field is concentrated at the top with a long tail of smaller filers. Recent-year momentum for the named leaders is flat or negative, which given publication lag likely reflects incomplete recent data rather than reduced activity.

Oil-injected designs dominate the most-cited historical patents in this corpus, with claims focused on oil atomization, cooling and separation to manage sealing and lubrication between rotors. Oil-free approaches appear far less frequently in the highly-cited set and show up as a smaller share of the overall filing volume, suggesting comparatively less-crowded claim space around dry or oil-free sealing geometries. Anyone filing in oil-free sealing should still check against the general clearance-sealing prior art, since sealing principles often transfer across both approaches.

The trend in this dataset shows a peak of 161 filings in 2018 easing to 81 by the 2022 midpoint, which typically indicates that core mechanical claim space — rotor profile geometry, basic sealing arrangements, standard oil management — was substantially filed earlier in the window. It does not mean the underlying technology stopped being commercially relevant; screw compressors remain widely deployed in HVAC and industrial gas handling. New filings now tend toward narrower refinements such as variable-speed control integration rather than foundational mechanical claims.

Japan leads with 654 filings in this corpus, ahead of the European Patent Office at 484, the United States at 400, and China at 376; WIPO/PCT filings add another 219 seeking multi-jurisdiction coverage. This distribution means a freedom-to-operate analysis focused only on US patents would miss the offices carrying the largest filing density. Japan's lead likely reflects the concentration of major compressor and HVAC manufacturers headquartered there.

US10941770B2, assigned to Trane International, claims a variable capacity screw compressor that runs the rotor at an optimum peripheral velocity independent of synchronous motor speed, using a variable-speed drive commanded by a controller to exceed synchronous speed at full-load capacity. This specific mechanism — decoupling rotor speed from motor synchronous speed via controller-commanded VSD — is what the claims protect, not variable-speed compression in general. Designs achieving capacity control through slide valves, bypass ports, or VSD schemes tied to synchronous speed reference points would sit outside this specific claim construction, though a full claim chart is needed to confirm freedom to operate.