Flywheel Energy Storage Patents: Who Leads, Where Gaps Are 2026
- Filings have already peaked. 2019 was the high point at 33 filings; by the 2022 midpoint activity had settled to 24, and the trend since reads flat to declining rather than growing.
- The top tier is real but not dominant. The leading assignee holds 26 records, and the top 5 combined account for 23.8% of all 408 records in scope — concentrated, but with a long tail of single- and few-filing entrants behind it.
- Electric-machine claims dominate the class map. H02K (motors & generators) appears on 86.0% of records, while grid-facing H02J claims sit on just 19.6% — the rotor and motor side is crowded, the power-electronics interface less so.
What the flywheel energy storage patent record shows
Flywheel energy storage stores electricity as rotational kinetic energy in a spinning rotor, then recovers it through a motor/generator running in reverse. The patent record in scope here — 408 records filed between 2015 and mid-2026 — is built around the search terms that define the modern engineering problem: composite rotor construction, magnetic bearings that remove friction losses, vacuum containment to cut windage, and the control electronics that manage self-discharge and grid frequency regulation. This is a mechanical-electrical hybrid field, and the IPC composition reflects that split.
Because publication typically lags filing by around 18 months, the most recent year in the trend (2026) is necessarily undercounted and should be read as a floor, not a ceiling. The picture that emerges from the rest of the window — a clear 2019 peak followed by a plateau — is unlikely to be reversed by that undercount alone.
Let an AI agent run this analysis on your own technology
Pick a task. Every answer cites the patents behind it.
Filing trend and technology composition
Filing volume and IPC composition together show a field that grew through the late 2010s, plateaued, and remains concentrated in electric-machine claims rather than in the grid or vehicle interfaces around it.
A 2019 peak followed by a flat-to-declining plateau
Filings rose from 19 in 2017 to a peak of 33 in 2019, then settled near the 2022 midpoint value of 24 — a pattern consistent with a technology that established its core claims early and has not since accelerated. The 2026 figure is partial due to publication lag and should not be read as a drop-off.
Electric machines dominate; grid interface is comparatively open
H02K (motors & generators) covers 86.0% of the 408 records, and F16F (springs & vibration dampers, relevant to rotor suspension) covers 41.4%. F16C (bearings & couplings) sits at 23.0% and H02J (power supply & grid systems) at 19.6% — the mechanical rotor and drive claims are far more heavily filed than the electrical grid-interface side, and vehicle-propulsion classes (B60L, B60K) each sit under 6%.
Shares are the percentage of the 408 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 with Eureka
This page is one run against one query. Ask Eureka your own question about flywheel energy storage and every answer comes back with the patent numbers behind it.
Try EurekaThe patents that anchor this field
Flywheel energy storage with PM, induction, or variable reluctance machine (US20190199164A1)
An integrated flywheel energy storage device includes an inner stator with multiple stator cores and coils arranged across electrical phases, and an outer rotor housing supporting active rotor poles that may be permanent magnets, copper relining, an induction squirrel cage, or variable reluctance poles. A vacuum containment housing surrounds the outer rotor housing, whose rotational moment of inertia stores kinetic energy as a kinetic battery for multi-phase output.Filed by Hamilton Sundstrand Corporation, 2019-06-27 — illustrates how rotor topology and vacuum containment claims are frequently bundled in a single filing.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US6710489B1 | Axially free flywheel system | 184 |
| 2 | US5614777A | Flywheel based energy storage system | 145 |
| 3 | US6897587B1 | Energy storage flywheel with minimum power magnetic bearings and motor/generator | 121 |
| 4 | US6262505B1 | Flywheel power supply having axial magnetic bearing for frictionless rotation | 112 |
| 5 | US4077678A | Energy storage apparatus | 102 |
| 6 | US5398571A | Flywheel storage system with improved magnetic bearings | 95 |
| 7 | US5214981A | Flywheel energy storage with superconductor magnetic bearings | 92 |
| 8 | US6664680B1 | Flywheel device with active magnetic bearings | 90 |
| 9 | US5767595A | Flywheel system for mobile energy storage | 83 |
| 10 | US4860611A | Energy storage rotor with flexible rim hub | 82 |
Citation counts favour older filings by construction — a searched corpus accumulates citations over time — so treat this table as a signal of technical influence on later filers, not of current commercial relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
Put your own technology through the same analysis
Eureka on the web
When you want the answer in the next five minutes.
The agent works the prompt against patents and technical literature, citing every source.
Run your analysis now →MCP server & REST API
When it has to run inside your own pipeline.
Patent search, landscape analysis and assignee resolution as MCP tools. Drop them into any agent framework, or call REST directly.
Browse MCP servers →What the numbers mean for a filing decision
Three patterns stand out once the ranking, class mix and receiving-office split are read together: concentration without total dominance, a mechanical claim base that is far more crowded than the electrical one, and a jurisdictional split that tracks the two largest manufacturing bases.
The top tier is thick but not a monopoly
The leading assignee holds 26 records and the top 5 combined reach 23.8% of the 408 records in scope. That leaves the large majority of filings spread across a long tail of single- and few-filing entrants — room to compete, but only outside the specific rotor and bearing claims the leaders already hold.
Rotor and motor claims crowd out the grid interface
H02K (motors & generators) sits on 86.0% of records while H02J (power supply & grid systems) sits on just 19.6%. Anyone designing a new machine topology is filing into dense prior art; anyone working the frequency-regulation and grid-coupling side has materially more open space.
Growth has already plateaued
Filing activity peaked in 2019 at 33 and had settled to 24 by the 2022 midpoint, with no clear reacceleration since. Recent-year momentum by assignee is similarly quiet across the tracked leaders, suggesting the core claim space was staked out early rather than being actively contested now.
Filing activity splits almost evenly between two offices
The United States (128) and China (120) lead receiving-office counts, well ahead of Europe (44), WIPO/PCT (41), Canada (17) and Australia (14). A freedom-to-operate check that only covers one of the two leading offices is checking half the field.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to flywheel energy storage, with the prior art for and against each one.
Who holds the claims, and where the field is still open
The ranked leaders combine large industrial players, dedicated flywheel specialists and a long tail of academic and single-filing entrants. Recent-year momentum across the tracked leaders is largely flat, which is consistent with a field whose core mechanical claims were staked out several years ago.
One clear leader, no runaway dominance
The top-ranked assignee holds 26 of the 408 records in scope — enough to set the pace on rotor and bearing design, but not enough to foreclose the field. Fifth place holds 16 records and tenth place holds 10, showing a gradual taper rather than a cliff.
Dedicated flywheel firms have gone quiet recently
Several assignees with an early flywheel focus — including dedicated flywheel-storage specialists and legacy motor/generator suppliers — show zero filings in the latest tracked year. That does not mean exit from the field, but it does mean their most recent published claims are the ones to check first for freedom-to-operate.
Co-filing is limited and mostly domestic
Only 10 co-assignee pairs appear across the dataset, and the strongest pairing links a Chinese energy-technology firm with a national defence-engineering research institute. Cross-border co-filing is rare here — most assignees, including the leaders, file independently.
| Assignee | Recent year | YoY |
|---|---|---|
| Jiangsu University | 1 | 0% |
| Satcon Technology Corporation | 0 | — |
| KineticCore Solutions LLC | 0 | — |
| HELIX POWER CORP | 0 | — |
| The Boeing Company | 0 | — |
| WATTSUP POWER AS | 0 | — |
| Amber Kinetics Inc. | 0 | — |
| University of Chicago | 0 | — |
Where to take this analysis
The dataset points to two practical next steps: checking freedom-to-operate against the densest rotor and bearing claims, and scoping a filing strategy for the grid-interface and self-discharge branches that remain comparatively open.
Run a freedom-to-operate check on rotor and bearing claims
With H02K at 86.0% of records and F16C at 23.0%, any new rotor or magnetic-bearing design should be checked against the leading assignees' most-cited filings before committing engineering resources.
Explore prior art in EurekaScope claims in the grid-interface white space
H02J coverage at 19.6% of records is comparatively light next to the mechanical classes, suggesting room for well-drafted frequency-regulation and grid-coupling claims that do not collide with the existing rotor-heavy portfolio.
Map white space in EurekaFrequently asked questions
The dataset in scope for this analysis contains 408 published records filed between 2015 and mid-2026, drawn from a search combining flywheel-specific terms with IPC classes covering motors, springs and power-supply systems. This is a defined search scope, not a count of every flywheel-related filing worldwide, so figures should be read as representative of the field's shape rather than an exhaustive total. Publication lag of roughly 18 months means the most recent year is understated in any such count.
The ranking is concentrated but not dominated by a single player: the top assignee holds 26 of the 408 records, and the top 5 combined account for 23.8% of all records in scope. Behind that leading group sits a long tail of assignees with far fewer filings each, including academic institutions and smaller specialist firms. This shape means new entrants can still find open claim space outside the specific rotor and bearing designs the leaders have already filed.
Electric machine design dominates: IPC class H02K, covering motors and generators, appears on 86.0% of the 408 records in scope. Springs and vibration-damping components (F16F) appear on 41.4%, and bearings and couplings (F16C) on 23.0%. Grid-facing power-supply systems (H02J) appear on only 19.6% of records, and vehicle-propulsion classes are smaller still — indicating the mechanical rotor and drive side is far more heavily claimed than the electrical grid interface.
Filing activity peaked in 2019 at 33 filings and had fallen back to 24 by the 2022 midpoint, with no clear resumption of growth since. Recent-year momentum data across several tracked leading assignees shows zero filings in the latest year, reinforcing a flat-to-declining picture rather than an accelerating one. The most recent year figure is still partial due to publication lag, but the multi-year plateau preceding it is a more reliable signal than any single year.
The clearest gaps sit in the grid-interface and control-electronics side of the field rather than in rotor or bearing mechanics, since H02J (power-supply and grid systems) covers only 19.6% of the 408 records against 86.0% for motor and generator claims. Specific branches worth examining include frequency-regulation control loops, self-discharge mitigation electronics, and hybrid flywheel-battery grid interfaces, all of which sit below the dense mechanical claim base. Co-filing is also rare in this field, with only 10 co-assignee pairs identified, suggesting collaborative filing strategies are underused.
Research Flywheel Energy Storage in depth with Eureka
Go past this page: query the whole flywheel energy storage corpus yourself, in your own scope.
Every answer comes back with patent numbers you can open.
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.