Screw Compressor Efficiency Patents: Who Leads, Trends 2026
- Filing has cooled since a 2017 peak of 15 records, with the 2022 midpoint down to 2 — this is a mature, not a growing, filing area.
- Japan leads receiving offices with 62 filings, ahead of the United States (45) and the EPO (38), showing where enforcement risk concentrates first.
- The five most-cited records all date to before 1997, meaning the foundational injection-cooling and sealing claims are decades old and likely expired or expiring.
What this landscape covers
This landscape tracks 241 patent families filed between 2015 and 2026 that combine screw compressor hardware claims with explicit efficiency language — volumetric efficiency, leakage reduction, isentropic efficiency or efficiency improvement — inside the core rotary-piston pump classification F04C18/16 and its efficiency-adjacent subclasses. The scope is deliberately narrow: it captures compressors where efficiency is claimed as the invention’s point, not compressors in general.
Because publication typically lags filing by around 18 months, the most recent year in the trend chart understates real filing activity and should be read as a floor, not a ceiling.
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Filing trend and technology composition
Two views of the same 241-family dataset: how filing volume has moved year over year, and which IPC subclasses the claims actually sit in.
A peak year behind us
Filings hit 15 in 2017 and had fallen to 2 by the 2022 midpoint, with the trend continuing toward zero into the most recent partial year. Read the tail end cautiously given publication lag, but the multi-year decline from peak is a real signal that core claim space has already been staked out.
Concentrated in rotary-piston machinery
Every record sits in F04C by construction of the search, but secondary classification shows real spread: F01C (rotary-piston machines, 38 records) and F25B (refrigeration and heat pumps, 27) are the largest adjacent groups, followed by F04B (positive-displacement pumps, 25) and F16J (seals and gaskets, 21). The small F16C, C23C and F01P counts mark bearings, coatings and cooling as thinly claimed extensions rather than core battlegrounds.
Shares are the percentage of the 241 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Screw Compressor Efficiency Enhancement with Eureka
This page is one run against one query. Ask Eureka your own question about screw compressor efficiency enhancement and every answer comes back with the patent numbers behind it.
Try EurekaThe foundational and representative filings
US5037282A — Rotary screw compressor with oil drainage
Filed via PCT and granted to Svenska Rotor Maskiner, this patent claims meshing male and female rotor shaft extensions journalled in bearings within high- and low-pressure end sections, with oil supplied to the bearing chambers for lubrication and cooling. Its distinguishing feature is draining the low-pressure end section's bearing chambers back into the working space through a defined path, rather than routing that oil through a separate external return.Granted 1991-08-06 · assignee Svenska Rotor Maskiner AB
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US3913346A | Liquid refrigerant injection system for hermetic electric motor driven helical screw compressor | 155 |
| 2 | US5653585A | Apparatus and methods for cooling and sealing rotary helical screw compressors | 101 |
| 3 | US3795117A | Injection cooling of screw compressors | 90 |
| 4 | US4180986A | Refrigeration system on/off cycle | 79 |
| 5 | US4490102A | Volumetric screw compressor | 56 |
| 6 | US4181474A | Vertical axis hermetic rotary helical screw compressor with improved rotary bearings and oil management | 53 |
| 7 | US6216474B1 | Part load performance of variable speed screw compressor | 50 |
| 8 | US5009583A | Shaft seal and bearing members for a rotary screw compressor | 45 |
| 9 | JP1984176490A | Screw compressor | 36 |
| 10 | WO1995018945A1 | Cooling and sealing rotary screw compressors | 30 |
Ranked by citation count within this searched corpus; older filings accumulate citations simply by having been available longer, so treat this as a map of influence, not of current commercial relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the numbers mean for a filing decision
Three read-throughs from the trend, geography and citation data — useful for deciding where a new filing is likely to face crowded prior art versus open ground.
Peak filing activity is behind this field
The drop from 15 filings in 2017 to 2 by 2022, with the trend continuing toward the most recent partial year, indicates that the core mechanical approaches to volumetric and isentropic efficiency in screw compressors were substantially claimed in the mid-2010s. New entrants should expect to compete on refinement claims rather than foundational geometry.
Japan is the primary filing venue, not the US
With 62 filings in Japan against 45 in the United States and 38 at the EPO, freedom-to-operate work for this technology needs to start with Japanese-office prior art, not default to a US-first search strategy.
The most influential prior art predates modern efficiency claims
The highest-cited records — covering liquid refrigerant injection, cooling and sealing, and injection cooling generally — were all published between the mid-1970s and mid-1990s. Their core mechanisms are long expired, which typically pushes remaining active risk into narrower, more recent dependent claims rather than the base concepts.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to screw compressor efficiency enhancement, with the prior art for and against each one.
Who holds the ground and where it is open
Assignee activity is spread thin: co-assignee pairings top out at two shared filings, and the most active named organisations show no filings in the latest tracked year, consistent with a field past its filing peak.
Collaboration is limited and inventor-anchored
The strongest co-assignee links pair a single corporate assignee with a named individual inventor at two shared filings each, rather than showing sustained multi-party programmes. This points to inventor-driven filing rather than joint-venture-style technology sharing.
Even the most active assignees have gone quiet recently
Every organisation tracked in the recent-momentum view — including Trane International, MAYEKAWA, Kobe Steel and Svenska Rotor Maskiner — shows zero filings in the latest year. That is consistent with the broader trend decline rather than any single company exiting the field.
No single assignee dominates the full period
With 241 families spread across many named assignees and no co-filing cluster exceeding two shared records, this is a long-tail landscape: useful prior art is distributed across many single-digit filers rather than concentrated in two or three portfolios.
| Assignee | Recent year | YoY |
|---|---|---|
| Kobe Steel, Ltd. | 0 | — |
| Mayekawa Mfg. Co., Ltd. | 0 | — |
| Trane International Inc. | 0 | — |
| DUNHARM BUSH INC | 0 | — |
| Svenska Rotor Maskiner AB | 0 | — |
| Compair UK Limited | 0 | — |
| Hokuetsu Industries Co., Ltd. | 0 | — |
| Ebara Corporation | 0 | — |
Where to take this analysis
The landscape points to a mature core with narrow openings at the edges. Two directions make sense depending on what you are deciding.
Check freedom-to-operate against Japanese filings first
With 62 of the tracked filings routed through the Japanese receiving office, any new efficiency claim in rotor geometry or oil management should be checked against that corpus before US or EPO prior art.
Explore assignee filings in EurekaProbe the thin secondary IPC branches for open claims
F16C, C23C and F01P each carry single-digit record counts against a 241-family core, suggesting bearing, coating and cooling approaches to efficiency remain comparatively open.
Run a white space search in EurekaCommon questions about this landscape
This landscape includes only records that combine screw compressor hardware — twin-screw, rotary screw or helical designs — with explicit efficiency language in the title or claims, such as volumetric efficiency, isentropic efficiency, leakage reduction or efficiency improvement. It is filtered to the F04C18/16 core classification and related efficiency subclasses, so general compressor patents without an efficiency claim are excluded. That makes the 241-family count a focused subset, not a count of all screw compressor patents.
The trend shows 15 filings in 2017 falling to 2 by the 2022 midpoint, and continuing to decline into the most recent partial year. This pattern typically means the foundational mechanical approaches — rotor profile, injection cooling, bearing sealing — were already well claimed by the mid-2010s, pushing later filers toward narrower, incremental improvements. It does not mean the underlying technology stopped being commercially relevant; filing volume and market activity are not the same measure.
Japan is the largest receiving office in this dataset with 62 filings, ahead of the United States at 45 and the European Patent Office at 38. If you are planning to manufacture or sell screw compressor technology, a Japanese-office prior art search should come before a US-only search, since the volume of relevant claims there is meaningfully higher. China, the UK and WIPO/PCT filings should also be checked, though at lower volumes of 25, 15 and 14 respectively.
The five most-cited records in this landscape were published between the mid-1970s and mid-1990s, including foundational work on liquid refrigerant injection and injection cooling of screw compressors. Given standard patent terms, the base claims in these records have very likely expired, which is why later filers build on their disclosed mechanisms rather than avoiding them. Always verify current legal status directly rather than assuming expiry from publication date alone, since term extensions and jurisdiction-specific rules can vary.
The secondary IPC composition shows F16C (bearings and couplings), C23C (coatings) and F01P (cooling) each carrying only single-digit record counts against the 241-family core, compared to 38 records in F01C and 27 in F25B. That imbalance suggests bearing lubrication paths, rotor surface coatings for leakage control, and oil-free cooling circuits are comparatively under-claimed relative to the core rotor and refrigeration-cycle claims. Any new filing strategy should verify this directly against current full-text claims before assuming an opening exists.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.