Fastest
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 →https://www.patsnap.com/resources/blog/rd-blog/abnormal-combustion-in-hydrogen-engines-patent-landscape/ · Patsnap · data cut-off 2026-07-31 · downloaded from the live page
Patent Landscape · Hydrogen EnginesAbnormal combustion patents in hydrogen engines: who controls knock, pre-ignition and backfire claims
- 22.3% concentration. The five most active filers together hold 2,042 of the 9,152 records in scope — a concentrated top with a long tail below it.
- Engine control and ignition dominate. F02D and F02P together anchor the field, at 32.7% and 27.1% of records respectively, well ahead of testing and measurement classes.
- Filing kept climbing into 2024. Filings rose from 254 in 2021 to 327 in 2024, a +29% increase, before the expected 18-month publication lag flattens the most recent years.
9,152
Published Records
22%
Top-5 Share of All Records
+29%
Filing Growth 2021→2024
US
Leading Jurisdiction
Filing growth compares 2021 (254 records) with 2024 (327) — 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 9,152 records in scope (CR5), not by the ranked leaders only.
Published byPatsnap Research··7 min readSourced from Patsnap Eureka
Field Overview
What this landscape covers
Abnormal combustion in hydrogen engines spans a specific set of failure modes — pre-ignition, backfire and knock — that arise from hydrogen's wide flammability range, low ignition energy and fast flame speed. The search set pulls records that combine these combustion-event terms with control-side language: injection timing, mixture stratification, hot-spot formation, residual gas influence, detection and control strategy. That pairing matters because a patent that only mentions knock in passing, without a control or detection claim, sits outside the set this page describes.
The 9,152 records in scope run from 2015 through the 2026-07-31 cut-off, giving a decade-long view of how engine-control and ignition-system filings have layered onto the older combustion-diagnostics base built for gasoline and diesel knock.
Records in scope by filing year
Source: Patsnap Eureka. Assignee ranking and totals. Derived from a Patsnap search on Abnormal Combustion in Hydrogen Engines covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
Let an AI agent run this analysis on your own technology
Pick a task. Every answer cites the patents behind it.
10,000 free credits to start
The Numbers
Filing trend and technology composition
Two views of the same 9,152-record set: how filing activity has moved year over year, and which IPC subclasses carry the claim volume.
A decade of steady, then accelerating, filing
Annual filings moved from 222 in 2017 to a peak of 327 in 2024, with the 2021-to-2024 span alone up 29%. Years after 2024 read lower only because publication lags filing by roughly 18 months — they are not yet complete and should not be read as a slowdown.
Engine control and ignition lead; measurement and testing trail
F02D (engine control) and F02P (ignition systems) are the two largest subclasses at 32.7% and 27.1% of the 9,152 records respectively. G01L, G01N and G01M — pressure measurement, material analysis and test-rig classes — sit well behind at 15.2%, 11.4% and 8.6%, and F02B (internal-combustion engines generally) accounts for 7.9%. Because records can carry multiple IPC classes, these shares add up to more than 100% and should be read individually, not summed.
Shares are the percentage of the 9,152 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Source: Patsnap Eureka. Filing trend and technology composition. Derived from a Patsnap search on Abnormal Combustion in Hydrogen Engines covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.
Go deeper on Abnormal Combustion in Hydrogen Engines with Eureka
This page is one run against one query. Ask Eureka your own question about abnormal combustion in hydrogen engines and every answer comes back with the patent numbers behind it.
Try EurekaKey Patents
A representative control-strategy claim
Representative Filing
US6925987B2 — Method for setting a knock determination period, fuel injection timing and control apparatus for an internal combustion engine
TOYOTA JIDOSHA KABUSHIKI KAISHA
Under engine operating conditions in which a default setting for a knock determination period overlaps with a fuel injection period during which fuel is injected by a fuel injector, the fuel injection timing and the knock determination period are set in correlation with each other such that the knock determination period is shorter than its default setting so the fuel injection period and the knock determination period no longer overlap. Accordingly, it is possible to avoid a case in which noise produced by operation of the fuel injector rides on an output signal from a knock sensor during the knock determination period, thus inhibiting a decrease in accuracy of knock determination.Filed by Toyota, published 2005-08-09 — a foundational timing-coordination approach that later hydrogen-specific filings build against or design around.
Most-cited records in the searched corpus
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20080168403A1 | Detecting and interpreting real-world and security gestures on touch and hover sensitive devices | 1,030 |
| 2 | US5589369A | Cells homozygous for disrupted target loci | 1,014 |
| 3 | WO2014093701A1 | Functional genomics using crispr-CAS systems, compositions, methods, knock out libraries and applications the… | 678 |
| 4 | US20140357530A1 | Functional genomics using crispr-cas systems, compositions, methods, knock out libraries and applications the… | 613 |
| 5 | US20130123338A1 | Novel cationic lipids and methods of use thereof | 526 |
| 6 | US20120202871A1 | Cationic lipids and methods for the delivery of therapeutic agents | 518 |
| 7 | US8569256B2 | Cationic lipids and methods for the delivery of therapeutic agents | 513 |
| 8 | WO2009132131A1 | Amino lipid based improved lipid formulation | 476 |
| 9 | WO2011141705A1 | Novel cationic lipids and methods of use thereof | 406 |
| 10 | WO2010039900A2 | Non-human mammals for the production of chimeric antibodies | 406 |
Citation counts inside this corpus skew toward older, foundational filings; treat them as a signal of influence rather than of current filing activity — several of the most-cited records here sit outside the hydrogen-engine core and reflect broader combustion-diagnostics prior art pulled in by the search terms.
Each row carries its publication number; clicking a row searches Eureka by that number.
Source: Patsnap Eureka. Citation counts and representative records. Derived from a Patsnap search on Abnormal Combustion in Hydrogen Engines covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
Run it yourself
Put your own technology through the same analysis
Where to run it
For builders
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 →Signal Check
What the filing pattern actually indicates
Three read-throughs from the same dataset, aimed at where a technical or IP team should look next.
Concentration
22.3%
of 9,152 records held by the top 5
A concentrated top, then a long tail
The five most active filers hold 2,042 records between them, and the top ten extend that to 3,097, or 33.8% of all records in scope. Below that threshold, filing activity spreads across the remaining 90 ranked companies, suggesting the core engine-control and ignition claim space is contested by a handful of automakers and Tier 1 suppliers while a much larger group files narrower, single-application improvements.
Ranking covers 100 companies, counted in records
Technology mix
32.7%
of records in F02D engine control
Control logic outweighs hardware
Engine control (F02D) and ignition systems (F02P) together dominate the composition, ahead of pressure measurement, material testing and dedicated internal-combustion-engine classes. That skew toward control and ignition claims — rather than sensor hardware or engine architecture — points to detection thresholds, timing correction and control-strategy logic as the areas with the densest prior art.
IPC shares sum above 100% because records carry multiple classes
Momentum
+29%
filing growth, 2021 to 2024
Growth through the last complete year
Filings rose from 254 in 2021 to 327 in 2024, the most recent year that can be treated as complete given an 18-month publication lag. Several of the leading assignees show a drop to zero filings in the latest partial year in the raw feed, which is an artefact of that lag rather than evidence of retreat from the space.
2025 and 2026 figures are still filling in
Eureka AI Agent
Looking for what nobody has claimed yet?
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to abnormal combustion in hydrogen engines, with the prior art for and against each one.
Source: Patsnap Eureka. Co-assignee relationships and derived observations. Derived from a Patsnap search on Abnormal Combustion in Hydrogen Engines covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
Who's Filing
The competitive set behind the ranking
Japanese automakers and their component suppliers anchor the leading positions, with a European Tier 1 and a US OEM inside the top group; the co-assignee pairs below show how closely an automaker and its component arm file together.
Leader position
674
records
A single filer well ahead of the field
The top-ranked assignee holds 674 records, more than double the fifth-place total of 269, which itself is well ahead of tenth place at 158. That gap between first and fifth is the clearest sign of a dominant filer rather than a tightly bunched leadership group.
Counted in patent families / records
Filing partnerships
171
shared records, strongest pair
Automaker–supplier pairs file together
The strongest co-assignee pair shares 171 records, and the next two strongest pairs sit at 112 and 106. These patterns point to joint engine-control development between an automaker and its component or research affiliate rather than arm's-length licensing.
10 co-assignee pairs identified in the dataset
Geographic filing
2,024
US-filed records
US, Japan and China carry most volume
The United States (2,024) and Japan (1,953) lead receiving-office counts, with China (1,386), the EPO (1,091), WIPO/PCT (640) and the UK (273) following. That spread indicates a field being protected across the three largest engine-manufacturing markets rather than concentrated in a single jurisdiction.
Receiving office counts, not deduplicated by family
Recent-year filing momentum
| Assignee | Recent year | YoY |
|---|---|---|
| Toyota Motor Corporation | 0 | -100% |
| Denso Corporation | 0 | — |
| Mitsubishi Electric Corporation | 0 | — |
| Robert Bosch GmbH | 0 | -100% |
| Nissan Motor Co., Ltd. | 0 | — |
| Mazda Motor Corporation | 0 | — |
| Ford Global Technologies, LLC | 0 | — |
| Hitachi, Ltd. | 0 | — |
Source: Patsnap Eureka. Assignee-level momentum. Derived from a Patsnap search on Abnormal Combustion in Hydrogen Engines covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
Next Steps
Where to take this analysis
The dataset points to specific next questions rather than a single conclusion — the right next step depends on whether you are scoping freedom-to-operate or looking for a filing gap.
Check freedom-to-operate against the leading cluster
With 22.3% of records held by five filers and dense co-assignee filing between automakers and their supplier arms, a claim chart against the leading cluster's engine-control and ignition filings is the fastest way to confirm exposure before committing R&D spend.
Run a claim comparison in EurekaMap the under-claimed branches in detail
The gate chips above point to specific sub-areas with thinner filing density than F02D or F02P; a targeted search across those branches can surface whether a first-filed claim is still realistically available.
Explore white space in EurekaSource: Patsnap Eureka. Forward-looking reading of the same dataset. Derived from a Patsnap search on Abnormal Combustion in Hydrogen Engines covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
FAQ
Common questions on this landscape
The dataset's assignee ranking shows a single filer well ahead of the rest, at 674 records against a fifth-place total of 269 and a tenth-place total of 158. The five most active filers together hold 2,042 records, or 22.3% of the 9,152 records in scope, and the top ten extend that to 33.8%. Beyond the leading group, filing activity spreads across a long tail of the remaining ranked companies, most holding far fewer records each.
Filings rose from 254 in 2021 to 327 in 2024, a 29% increase over that three-year span, and 2024 is the peak year recorded so far. Filing counts for 2025 and 2026 appear lower in the raw data, but that reflects the roughly 18-month lag between filing and publication rather than an actual drop in activity. Any read of the trend should treat 2024 as the most recent complete year.
The two largest IPC subclasses are F02D (engine control), covering 32.7% of the 9,152 records, and F02P (ignition systems), covering 27.1%. Pressure measurement (G01L), material analysis (G01N) and test-rig classes (G01M) follow at 15.2%, 11.4% and 8.6% respectively, with general internal-combustion-engine classifications (F02B) at 7.9%. Because a single record can carry several IPC classes, these percentages add up to more than 100% and should each be read against the full 9,152-record base, not against each other.
US6925987B2 is a Toyota filing, published 2005-08-09, that claims a method for setting a knock determination period so it no longer overlaps with the fuel injection period, avoiding injector noise corrupting the knock sensor signal. It covers the specific technique of shortening the knock determination window and correlating it with injection timing rather than knock detection or hydrogen combustion generally. Anyone building a knock-window-versus-injection-timing coordination scheme should check this filing directly rather than assume it only affects gasoline applications, since the claim language is engine-general.
The densest claim activity sits in engine control (F02D) and ignition systems (F02P), which together anchor the field; adjacent areas such as hydrogen-specific hot-spot suppression coatings, non-optical backfire-onset detection and residual gas fraction estimation for lean hydrogen mixtures show comparatively thinner coverage. These are not guaranteed-clear areas, but they sit outside the two dominant subclasses and are worth a targeted search before committing to a filing strategy. Co-assignee filing patterns also suggest that joint automaker-supplier development, rather than solo filing, may be the more contested route in the core control space.
Answers are grounded in the same dataset. Derived from a Patsnap search on Abnormal Combustion in Hydrogen Engines covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
Research Abnormal Combustion in Hydrogen Engines in depth with Eureka
Go past this page: query the whole abnormal combustion in hydrogen engines 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.