Screw Compressor Patents: Leaders, Trends & White Space 2026
- Filing peaked in 2017 at 41 records and has declined since, with the 2022 midpoint at just 12 — this is a maturing claim space, not a growing one.
- The top 5 assignees hold 33.1% of all 484 records, and the top 10 hold 55.0% — concentration builds fast after the leader, then flattens into a long tail.
- Rotary-piston pumps (F04C) cover 94.0% of records, while separation processes (B01D) sit at just 7.4% — a narrow band carries almost every filing.
What this landscape covers
This dataset covers 484 published records filed between 2015 and mid-2026 under a search scoped to rotor profile and clearance, volumetric and isentropic efficiency, oil separation, variable Vi, and pulsation and noise, within IPC classes F04C18, F04C29 and F25B1. It captures both oil-injected and oil-free screw compressor designs, spanning refrigeration, industrial gas handling and commercial vehicle braking-air applications.
Publication lags filing by roughly 18 months, so the most recent year in the trend line is understated and should be read as a floor, not a ceiling. Family counts, not raw document counts, are used for the assignee ranking to neutralise multi-jurisdiction filing strategies.
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Filing trend and technology composition
Two views of the same 484 records: how filing volume has moved year over year, and how those records distribute across IPC subclasses.
A peak in 2017, then a steady decline
Filings hit 41 in 2017, the high point of the window, then fell to 12 by the 2022 midpoint and to a single record in the partial 2026 year. Read the tail end cautiously — publication lag means 2025 and 2026 are still filling in.
Concentrated in rotary-piston pumps
F04C (rotary-piston pumps) appears in 94.0% of the 484 records, confirming this is the anchor classification for the field. F25B (refrigeration and heat pumps, 16.9%) and F04B (positive-displacement pumps, 13.6%) are the next largest adjacent classes, while B01D (separation processes, 7.4%) and F01C (rotary-piston machines, 3.5%) mark the smaller peripheral branches. Because records can carry multiple IPC codes, these shares sum to well over 100% of the record total — that overlap is expected and reflects how compressor filings routinely span mechanical and thermal classifications.
Shares are the percentage of the 484 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Screw Compressors with Eureka
This page is one run against one query. Ask Eureka your own question about screw compressors and every answer comes back with the patent numbers behind it.
Try EurekaThe most-cited records in this space
Oil injected screw compressor (US6991443B2)
An oil injected screw compressor integrates the oil separating mechanism with the compressor body for a compact design. Male and female rotors sit in a rotor casing with shafts arranged horizontally; an inner cylindrical wall beneath the rotor casing runs on a vertical axis, with an outer wall arranged concentrically. A lower casing joins hermetically to the outer wall, and oil in the compressed working gas is primarily separated from that gas by this arrangement before discharge.Filed by Hitachi Industrial Equipment Systems Co., Ltd., published 2006-01-31.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US3922114A | Hermetic rotary helical screw compressor with improved oil management | 98 |
| 2 | US4957517A | Sound attenuating liquid-gas separator | 69 |
| 3 | US6217304B1 | Multi-rotor helical-screw compressor | 61 |
| 4 | US4179248A | Oil equalization system for parallel connected hermetic helical screw compressor units | 61 |
| 5 | US6364645B1 | Screw compressor having a compressor screw housing and a spaced outer housing | 60 |
| 6 | US4662190A | Integral slide valve-oil separator apparatus in a screw compressor | 58 |
| 7 | JP2004137934A | Adjustable vi type inverter screw compressor | 55 |
| 8 | US4220197A | High speed variable delivery helical screw compressor/expander automotive air conditioning and waste heat ene… | 55 |
| 9 | US4181474A | Vertical axis hermetic rotary helical screw compressor with improved rotary bearings and oil management | 53 |
| 10 | US6045344A | Oil-cooled type screw compressor | 48 |
Citation counts are drawn from within this searched corpus and favour older filings that have had more time to accumulate citations — treat them as a signal of influence on later filers, not a measure of current relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the filing pattern tells you
Three findings that shape where to file next and what prior art to clear first.
A steep top, then a long tail
The leader holds 40 records against a fifth-place figure of 24 and a tenth-place figure of 19 — concentration is real at the very top but flattens quickly. Below the ranked leaders sits a long tail of single- and few-filing entrants, typical of a field where the core mechanical layout is settled and remaining innovation is incremental.
Filing activity has cooled since 2017
Volume ran flat-to-declining from the 2017 peak through the 2022 midpoint of 12 records, and several of the most active historical filers show zero filings in the latest year. That pattern points to a technology where the dominant design is established and new filing is increasingly defensive rather than exploratory.
Rotary-piston claims dominate the class map
F04C covers the overwhelming majority of records, with F25B and F04B as the next-largest adjacent classes at 16.9% and 13.6%. Separation processes (B01D, 7.4%) and rotary-piston machines (F01C, 3.5%) are comparatively thin, suggesting less claim density around post-compression handling than around the core rotor mechanism itself.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to screw compressors, with the prior art for and against each one.
Who holds the claims
Filing is concentrated among a handful of industrial compressor and refrigeration manufacturers, with collaboration patterns that trace specific engineering partnerships.
One clear leader, then a graded drop-off
The top assignee holds 40 records, well ahead of the fifth-place figure of 24 and the tenth-place figure of 19. That gap suggests one organisation has built a defensive filing programme around its core rotor and oil-management designs rather than relying on a single flagship patent.
A small set of recurring co-filing relationships
Ten co-assignee pairs appear in the dataset, with the strongest pairing recurring at 17 shared records. These repeated pairings point to stable engineering partnerships around specific rotor or compressor-housing designs rather than one-off joint filings.
Filing is spread across three major offices
The United States, Japan and China each receive more filings than the EPO, WIPO or India, indicating three separate regional battlegrounds rather than one dominant filing venue. A freedom-to-operate check for this technology needs to clear all three, not just one.
| Assignee | Recent year | YoY |
|---|---|---|
| Kobe Steel, Ltd. | 0 | — |
| Gree Electric Appliances, Inc. of Zhuhai | 0 | — |
| Hitachi, Ltd. | 0 | — |
| Knorr-Bremse Systeme fuer Nutzfahrzeuge GmbH | 0 | — |
| Hitachi Industrial Equipment Systems Co., Ltd. | 0 | — |
| Mitsubishi Electric Corporation | 0 | — |
| American Standard Inc. | 0 | — |
| Carrier Corporation | 0 | -100% |
Where to take this analysis
The dataset points to specific follow-up work depending on whether you are clearing freedom-to-operate or scouting where to file next.
Map the top assignee's full claim scope
With 40 records versus 19 at tenth place, the leading assignee likely holds layered claims across rotor profile, oil separation and housing geometry. A claim-by-claim breakdown clarifies which sub-areas are actually blocked versus merely occupied.
Explore assignee claim scope in EurekaCheck the under-claimed sub-areas against your own design
Variable Vi control and discharge pulsation damping show thinner filing density than the core rotor mechanism. Before assuming open space, confirm there is no unpublished pending application in the 18-month lag window.
Run a white-space check in EurekaVerify jurisdiction coverage for your target markets
With filings split across the US, Japan and China at comparable volumes, a single-jurisdiction search will miss significant prior art. Cross-check all three major offices plus the EPO and WIPO filings before finalising a filing strategy.
Compare jurisdiction coverage in EurekaCommon questions about screw compressor patents
The dataset ranks 100 companies by patent family count, and the leading assignee holds 40 of the 484 records in scope, well ahead of the fifth-place figure of 24 and tenth-place figure of 19. This is not a single-company monopoly — the top 5 combined account for 33.1% of all records and the top 10 for 55.0%, meaning nearly half of all filings come from outside the ranked leaders. Anyone doing competitive tracking should watch the leader closely but also monitor the long tail, since single-filing entrants can still hold a blocking claim in a narrow sub-area.
Filing activity peaked in 2017 at 41 records and has trended flat to declining since, with the 2022 midpoint at just 12 records. Several historically active assignees show zero filings in the most recent year. Because publication lags filing by roughly 18 months, the very latest years understate true activity, but the multi-year decline predates that lag effect and reflects a genuinely cooling filing pace rather than a reporting artefact.
Rotary-piston pump claims under IPC class F04C appear in 94.0% of the 484 records, making it by far the dominant classification. Refrigeration and heat pump applications (F25B) and general positive-displacement pumps (F04B) are the next-largest adjacent areas at 16.9% and 13.6% respectively. Separation processes and rotary-piston machines outside the core F04C class are comparatively thin, which is where a lower-density claim landscape may leave more room to file.
US6991443B2 covers an oil-injected screw compressor with an oil separating mechanism integrated directly into the compressor body, using a rotor casing with horizontally arranged male and female rotor shafts and a concentric inner-and-outer wall arrangement beneath the casing for compact oil separation. It does not block every oil-injected design — it specifically constrains the integrated separator geometry described in its claims. Designs using external or differently arranged separation mechanisms, or oil-free architectures entirely, sit outside its direct scope, though a full freedom-to-operate check should confirm this against the claim language itself.
The United States leads with 110 filings, followed closely by Japan at 99 and China at 81, with the EPO, WIPO and India trailing at 60, 31 and 25 respectively. This three-way split across the US, Japan and China means a filing or clearance strategy focused on only one of these jurisdictions will miss a substantial share of relevant prior art. Companies scouting global freedom-to-operate should treat all three as primary search venues rather than picking one as representative.
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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.