Air Cycle Machines Patents: Who Leads, Where the Gaps Are 2026
- 82.0% of filings sit with five assignees. the leader alone accounts for 1,277 of the 2,041 records in scope, leaving a long tail for everyone else.
- Filing activity has pulled back. 2021 to 2024 filings fell 41% (127 to 75), from a 2017 peak of 274 — publication lag means the last year or two will still fill in.
- B64D aircraft-equipment claims dominate the field. 76.9% of records carry a B64D class, while separation processes and heat-exchanger detail claims sit far thinner at 10.3% and 6.1%.
Filing growth compares 2021 (127 records) with 2024 (75) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 2,041 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
Air cycle machine and pack design patents cover the compressor, turbine, condenser and water-extraction hardware that conditions bleed air for aircraft cabins, along with the ducting and control logic that ties an air conditioning pack together. The search string used here pairs core pack terms with the specific mechanical failure points and outputs engineers actually claim around: ram air duct routing, water extractor performance, expansion turbine work extraction, compressor surge margins, condenser design, and pack outlet temperature control.
The scope runs from 2015 through the current data cut-off in mid-2026, spanning 2,041 published records assigned to 2,041 patent families. Because families rather than raw document counts anchor the assignee ranking, the concentration figures below are not inflated by continuation filings or multi-jurisdiction duplicates.
Filing trend and technology composition
Two views of the same 2,041-record dataset: how filing volume has moved year over year, and which IPC subclasses carry the claim density within those records.
Filing trend: a 2017 peak, then a step down
Filings peaked at 274 in 2017. From 2021 to 2024 — the most recent span that can be read as complete once publication lag is accounted for — filings dropped from 127 to 75, a 41% decline. Treat 2025 and 2026 figures as still filling in rather than as evidence of a further fall.
IPC composition: aircraft-equipment claims dominate
B64D (aircraft equipment) appears on 76.9% of the 2,041 records, far ahead of F25B refrigeration and heat-pump claims (17.1%) and F02C gas-turbine plant claims (14.0%). Separation processes (B01D, 10.3%), heat-exchanger details (F28F, 6.1%), turbine mechanics (F01D, 5.5%), pump hardware (F04D, 5.5%) and general air-conditioning control (F24F, 5.5%) sit well below that, marking where claim density thins out. Because records can carry multiple classes, these shares add up to more than 100% and should be read against the 2,041-record total, not against each other.
Shares are the percentage of the 2,041 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Air Cycle Machines and Pack Design with Eureka
This page is one run against one query. Ask Eureka your own question about air cycle machines and pack design and every answer comes back with the patent numbers behind it.
Try EurekaMost-cited records and a representative filing
US20190291875A1 — Cooling system, air conditioning pack, and method for conditioning air
An air conditioning pack of a cooling system includes an air cycle machine assembly, a cabin air compressor assembly, and a mixing duct. The air cycle machine assembly includes a compressor configured to receive an air stream that includes bleed air to generate a compressed air stream. The air cycle machine assembly utilizes a first portion of the compressed air stream to power the compressor. The cabin air compressor assembly receives a second portion of the compressed air stream, and utilizes the second portion to generate compressed ram air. The mixing duct receives the compressed ram air and allows it to mix with the air stream upstream of the compressor.Filed by The Boeing Company, published 2019-09-26.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US9005199B2 | Heat management configurations for controlling heat dissipation from electrosurgical instruments | 360 |
| 2 | US5461882A | Regenerative condensing cycle | 334 |
| 3 | US9737358B2 | Heat management configurations for controlling heat dissipation from electrosurgical instruments | 263 |
| 4 | US5442905A | Integrated power and cooling environmental control system | 212 |
| 5 | US4262495A | Cabin-air recirculation system powered by cabin-to-ambient pressure differential | 203 |
| 6 | US5299763A | Aircraft cabin air conditioning system with improved fresh air supply | 202 |
| 7 | US5704218A | Integrated environmental control system | 174 |
| 8 | US20110306968A1 | Heat management configurations for controlling heat dissipation from electrosurgical instruments | 146 |
| 9 | US4966005A | Advanced hybrid air/vapor cycle ECS | 142 |
| 10 | US20140251585A1 | Micro-lattice Cross-flow Heat Exchangers for Aircraft | 127 |
Citation counts favour older records simply by virtue of having had longer to accumulate them — read this table as a map of influential prior art, not a ranking of current importance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Three readings of the same dataset, each pointing at a different decision a filer or licensing team needs to make.
Five assignees hold most of the claim space
The leading assignee alone accounts for 1,277 records, and the next four combined bring the top-5 share to 1,674 records — 82.0% of everything in scope. That leaves the remaining 18% spread across a long tail of single- and few-filing entrants, which is a narrow gap for a newcomer to work through without a licensing conversation.
Filing volume has stepped down from its 2017 peak
After peaking at 274 filings in 2017, annual output fell to 127 by 2021 and to 75 by 2024 — a 41% decline across that three-year window. The leading assignees show no filings in the latest tracked year, but publication lag of roughly 18 months means the most recent years understate true filing activity rather than confirming a further drop.
Aircraft-equipment claims crowd the core, thinner elsewhere
B64D aircraft-equipment claims sit on more than three-quarters of the 2,041 records, while refrigeration (F25B) and gas-turbine (F02C) classes trail well behind. Separation processes, heat-exchanger detail and air-conditioning control classes each sit at 10% or under, marking where claim density is comparatively light.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to air cycle machines and pack design, with the prior art for and against each one.
Who is filing, and where the door is still open
The assignee ranking covers 100 companies drawn from the full set of 2,041 records — it is not a top-50 or top-100 cut, it is the entire ranking the dataset returns.
One assignee dominates the family count
The top-ranked assignee alone accounts for well over half of all records in scope, a scale that reflects decades of incumbency in pack hardware supply to the major airframers rather than a recent filing surge.
A steep drop after the leader
By the fifth position, family counts have fallen to 62 — a fraction of the leader's total — showing how sharply concentration tapers even within the top tier before it flattens into the tail.
The tail starts early
By rank ten, family counts are down to 17, and the top 10 combined still only reach 90.2% of all records — meaning the remaining 90 ranked assignees split the last one-tenth of the field between them.
| Assignee | Recent year | YoY |
|---|---|---|
| Hamilton Sundstrand Corp | 0 | -100% |
| Honeywell International Inc | 0 | — |
| The Boeing Company | 0 | — |
| RTX Corp | 0 | -100% |
| United Technologies Corp | 0 | — |
| Airbus Operations GmbH | 0 | — |
| Rolls-Royce plc | 0 | -100% |
| Liebherr Aerospace Lindenberg GmbH | 0 | — |
Where to take this analysis
The figures above set the boundaries of the field; the next step is usually narrower — a freedom-to-operate check on a specific mechanism, or a closer look at what the leading assignees are still actively filing.
Check freedom-to-operate on a specific mechanism
Run a targeted search against the co-assignee and inventor combinations behind the densest B64D and F25B claims before committing to a design direction.
Explore in Patsnap Eureka →Track the leading assignees' active filings
Recent-year momentum shows the top assignees at zero filings in the latest tracked year, which given publication lag is worth revisiting as later years fill in.
Set up monitoring in Patsnap Eureka →Common questions on air cycle machine patents
Very concentrated at the top. The top five assignees together hold 1,674 of the 2,041 records in scope, or 82.0% of the field, and the single leading assignee accounts for 1,277 records on its own. Beyond the top ten — which reach 90.2% combined — coverage falls off quickly into a long tail of assignees with only a handful of filings each. This means most freedom-to-operate questions in this field come back to a small handful of incumbents rather than a diffuse field of small filers.
Filing volume has declined from a 2017 peak of 274 to 75 in 2024, a 41% drop between 2021 and 2024 specifically. That said, publication lags actual filing dates by roughly 18 months, so 2025 and 2026 figures in any dataset will look artificially low and should not be read as continued decline. The honest read is that the field cooled off after 2017 rather than that it is actively contracting today.
B64D, the aircraft-equipment classification, appears on 76.9% of the 2,041 records in scope, making it by far the densest claim area. F25B refrigeration and heat-pump claims (17.1%) and F02C gas-turbine plant claims (14.0%) follow well behind. Separation processes, heat-exchanger detail, turbine mechanics, pump hardware and general air-conditioning control classes each sit at or below 10.3%, marking the areas with comparatively lighter claim density.
US20190291875A1, filed by The Boeing Company and published 2019-09-26, describes an air conditioning pack combining an air cycle machine compressor stage, a separate cabin air compressor assembly, and a mixing duct that blends compressed ram air back into the bleed air stream upstream of the compressor. It matters because it sits squarely in the B64D and F02C claim clusters that carry the densest coverage in this dataset, so any new pack architecture that splits compression duties between a bleed-air-driven stage and an independently powered stage needs to be checked against it specifically.
The densest claim clusters sit in core B64D aircraft-equipment and F25B refrigeration classes, while adjacent mechanisms — water extractor coalescing media, expansion turbine bearing health monitoring, compressor surge margin sensing, and pack outlet temperature blending control — show comparatively thin coverage relative to the core architecture. These are not unclaimed, but they carry far fewer records than the dominant pack-cycle claims, making them worth a closer look before assuming the space is occupied. A prior-art search focused specifically on these sub-mechanisms, rather than on the pack as a whole, is the more efficient way to confirm actual white space.
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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.