Flywheel Energy Storage Patents: Leaders, Trends & White Space 2026
- Filing peaked in 2017 at 6 records and has not recovered, with the 2022 midpoint back down to 3 — this is a mature claim space, not a growth one.
- H02K (electric motors & generators) touches 94 of 100 families, while B64G (spacecraft) appears in only 3 — the aerospace angle is barely claimed relative to the grid-storage core.
- The most-cited record, US6710489B1, carries 184 citations, and the top five most-cited patents all predate 2006 — influence here is historical, not a signal of current activity.
What the flywheel energy storage patent record actually shows
The dataset covers 100 published patent families filed against a search built around magnetic bearing rotors, composite flywheels, vacuum containment and high-speed rotor claims, spanning 2015 through the 2026 cut-off. Filing activity is not accelerating: it peaked in 2017 and has trended flat-to-down since, with the 2022 midpoint sitting at half the peak. That pattern is consistent with a technology whose core mechanical claims were staked out a decade or more ago, and where new filings are now incremental refinements rather than foundational architecture.
Classification data confirms where the claim density actually sits. H02K (electric motors and generators) appears in the overwhelming majority of families, with H02J (grid integration) and F16F (springs and vibration damping) as secondary clusters. Bearing and shaft mechanics (F16C) and motor control (H02P) are present but thinner, and spacecraft applications (B64G) barely register — a gap worth noting given flywheels' established role in satellite attitude control and power regulation.
Filing trend and technology composition
Publication counts for the most recent one to two years understate true filing activity, since publication typically lags filing by around 18 months. Read the trend and IPC breakdown together: they show where claim density has built up and where it has not.
A decade past its filing peak
Filings ran at 6 in 2017, fell toward a 2022 midpoint of 3, and sit at 1 in the most recent (partial) year. There is no second wave visible in this corpus — flywheel storage patent activity in this search scope is contracting, not building.
Concentrated in motor/generator architecture
H02K covers 94 of 100 families, making it the dominant classification by a wide margin. H02J (39) and F16F (37) form a secondary tier tied to grid interconnection and vibration isolation; F16C, F03G, H02P, H01F and B64G thin out fast, marking the edges of where this technology has been claimed.
Shares are the percentage of the 100 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Flywheel Energy Storage Technology Landscape with Eureka
This page is one run against one query. Ask Eureka your own question about flywheel energy storage technology landscape and every answer comes back with the patent numbers behind it.
Try EurekaThe patents setting the citation baseline
US20190199164A1 — Flywheel energy storage with pm, induction, or variable reluctance machine
An integrated flywheel energy storage device includes an inner stator with multiple stator cores and coils arranged in electrical phases, and an outer rotor housing carrying active rotor poles that may be permanent magnets, copper relining, an induction squirrel cage, or variable reluctance poles. A vacuum containment housing surrounds the rotor. The rotor's moment of inertia stores kinetic energy as a kinetic battery, discharging it as multi-phase electrical output.Filed by Hamilton Sundstrand Corporation, 2019-06-27.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US6710489B1 | Axially free flywheel system | 184 |
| 2 | US6897587B1 | Energy storage flywheel with minimum power magnetic bearings and motor/generator | 121 |
| 3 | US6664680B1 | Flywheel device with active magnetic bearings | 90 |
| 4 | US20050040776A1 | Flywheel energy storage systems | 85 |
| 5 | US4870310A | Portable crash-survivable kinetic energy storage machine | 73 |
| 6 | US20100018344A1 | Composite Hub for High Energy-Density Flywheel | 66 |
| 7 | US6707187B1 | Flywheel system with tilt switch | 60 |
| 8 | US6995529B2 | Flywheel energy storage systems | 57 |
| 9 | US6798092B1 | Low outgas flywheel motor/generator | 44 |
| 10 | US20030061898A1 | Crash management system for implementation in flywheel systems | 29 |
Citation counts inside a searched corpus accumulate over time, so older filings will always lead. Treat this table as a map of foundational prior art to design around, 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 things stand out once the trend, the classification spread and the citation graph are read side by side: the field's core mechanics were settled early, most recent activity is refinement rather than invention, and a handful of assignee-inventor pairs account for a disproportionate share of related filings.
The core architecture is not being re-invented
A 2017 peak followed by a decline to a 2022 midpoint of 3, and 1 in the latest partial year, indicates the foundational magnetic-bearing and composite-rotor mechanics were largely claimed in the prior decade. New entrants are more likely to be filing around existing architecture than proposing new ones.
Motor/generator claims dominate; spacecraft use is thin
H02K appears in 94 of 100 families, versus just 3 for B64G. Flywheels are established in satellite and spacecraft power systems, so a classification gap this wide against the terrestrial grid-storage core suggests aerospace-specific claim language is comparatively open.
Influence sits with pre-2006 filings
All five most-cited records in this corpus predate 2006. That is a citation-count artefact of corpus age as much as a statement about relevance, but it also means the prior art anyone files against today was set a generation ago and is well tested.
Collaboration is narrow and inventor-led
Only 7 co-assignee pairs appear across the dataset, the strongest being a single inventor pairing appearing 4 times. This is a field of largely solo corporate filers rather than joint ventures or cross-licensing consortia.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to flywheel energy storage technology landscape, with the prior art for and against each one.
| Assignee | Co-assignee | Shared families |
|---|---|---|
| MCMULLEN PATRICK T | HUYNH CO SI | 4 |
| INDIGO ENERGY INC | GABRYS CHRISTOPHER W | 2 |
| INDIGO ENERGY INC | CAMPBELL DAVID R | 2 |
| Université Laval (Laval University) | TREMBLAY LOUIS | 2 |
| Université Laval (Laval University) | DUBOIS MAXIME R | 2 |
| Université Laval (Laval University) | DESJARDINS MICHAEL | 2 |
| Université Laval (Laval University) | RUEL JEAN | 1 |
With only 7 co-assignee pairs in 100 families, most filers here are protecting positions independently rather than through joint development.
Who holds the ground, and where none of them are currently filing
Recent-year momentum across the leading assignees in this dataset is flat: none of the most cited or most active assignees on record show filings in the latest year, which fits the broader picture of a field that has stopped expanding its claim base.
The historical leaders have gone quiet
Assignees with the deepest filing histories in this corpus, including Beacon Power Corp, Indigo Energy Inc and Helix Power Corp, show zero filings in the most recent year. That does not mean these programmes are dead, but it does mean current activity is not visible in this dataset's newest layer.
A small number of named inventors anchor the strongest links
The MCMULLEN PATRICK T and HUYNH CO SI pairing appears 4 times, ahead of the two Indigo Energy Inc pairings at 2 each. Tracking named inventors, not just corporate assignees, is useful here given how often the same individuals recur across filings.
US filing leads, but PCT and China are not far behind
United States receives the largest share of filings at 39, with WIPO (PCT) at 14 and China at 12 close behind Europe at 11. Australia and Canada each hold 7, indicating the technology has been protected across a genuinely international spread rather than concentrated in one jurisdiction.
| Assignee | Recent year | YoY |
|---|---|---|
| Management Services Group, Inc. (trading as Global Technology Systems) | 0 | — |
| SIBLEY LEWIS B | 0 | — |
| BEACON POWER CORP | 0 | — |
| KAZAK TECH INC | 0 | — |
| HELIX POWER CORP | 0 | — |
| INDIGO ENERGY INC | 0 | — |
| Université Laval (Laval University) | 0 | — |
| MCMULLEN PATRICK T | 0 | — |
Where to take this from here
The dataset points to specific next steps depending on whether the goal is freedom-to-operate, competitive tracking, or identifying open claim space.
Run a freedom-to-operate check on the top-cited patents
US6710489B1, US6897587B1 and US6664680B1 anchor the citation graph and likely define the boundaries of magnetic bearing and active-bearing rotor claims that any new filing needs to design around.
Explore prior art in EurekaTrack the quiet incumbents
Beacon Power Corp, Indigo Energy Inc and Helix Power Corp show no recent filings in this corpus but hold historical depth; watch for continuation filings or ownership changes rather than assuming the position is abandoned.
Set up assignee monitoring in EurekaScope a filing in the under-claimed branches
Spacecraft power regulation and variable reluctance rotor pole design both sit well below the H02K core in filing density, suggesting room for a narrowly drafted first claim.
Draft claim scope in EurekaCommon questions on flywheel energy storage patents
The dataset's most cited and historically active assignees include Beacon Power Corp, Indigo Energy Inc, Helix Power Corp and Kazak Tech Inc, alongside individual inventor filings such as Sibley Lewis B. None of these leading assignees show filings in the latest tracked year, which suggests the field's most established players have either shifted strategy, been acquired, or are simply not filing new patents in this specific claim space right now. For current commercial activity, cross-reference these names against company filings and news rather than relying on patent data alone, since publication lags filing by roughly 18 months.
Based on this dataset, filing activity is slowing. It peaked in 2017 at 6 records, dropped to a 2022 midpoint of 3, and stands at just 1 in the most recent partial year. This flat-to-declining trend suggests the foundational mechanical architecture, particularly around magnetic bearings and composite rotors, was substantially claimed in the prior decade, and that recent activity is incremental rather than foundational. The most recent year should still be read cautiously given normal publication delay.
H02K, covering electric motors and generators, dominates this corpus, appearing in 94 of 100 families. H02J (power supply and grid systems) and F16F (springs and vibration dampers) form a secondary tier at 39 and 37 families respectively. Bearing and shaft mechanics under F16C, and motor control under H02P, are present but thinner, while spacecraft-related B64G classifications appear in only 3 families, marking a comparatively open area relative to the terrestrial grid-storage focus of the rest of the corpus.
US6710489B1, titled 'Axially free flywheel system', is the most cited record in this corpus at 184 citations. High citation counts inside a fixed, searched corpus tend to accumulate with age rather than purely reflect ongoing relevance, and this patent predates 2006 along with the other four most-cited records in the dataset. That said, its citation depth marks it as foundational prior art for axial flywheel bearing configurations, and any new filing in that specific mechanical space should be checked against it directly.
The classification data points to several under-claimed branches: spacecraft and satellite power regulation applications (B64G overlaps with the H02K core), variable reluctance rotor pole configurations, vacuum containment thermal management, and motor control algorithms specifically for high-speed rotor stability. These branches show meaningfully lower filing density than the H02K, H02J and F16F core, but a formal freedom-to-operate search is still recommended before treating any of them as genuinely clear.
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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.