PlainPatent

CPC technology class · F23

F23M - Casings

Casings, linings, walls or doors specially adapted for combustion chambers, e.g. firebridges; devices for deflecting air, flames or combustion products in combustion chambers; safety arrangements specially adapted for combustion apparatus; details of combustion chambers, not otherwise provided for. 568 US utility patents granted 2015–2025, with the leading assignees and year-by-year grant trajectory.

568
US patents granted
#9/12
in F23
3.7%
F23 class share
-28%
5-yr velocity

The verdict

According to USPTO PatentsView, Casings ranks #526 of 670 CPC technology areas - 568 US patents granted since 2015, with recorded grant volume down 28% over five years.

#526
of 670 CPC technology areas
568
US patents granted, 2015–2025
General Electric
leading assignee (45)
-28%
grant velocity, last 5 yrs

How F23M's grant cadence moved

Between 2020–2024, F23M recorded 221 grants versus 308 in 2015–2019 (-28% equal-window velocity). Across complete years, output peaked in 2019 at 89 grants and bottomed in 2024 at 25 (+256% peak-over-trough). Lead assignee Ansaldo Energia Switzerland AG holds 3.0% of the class ; the top three share 6.2%.

Leaderboard read

F23M concentration, lead at 3.0%

Ansaldo Energia Switzerland AG leads this historical grant record at 3.0% of F23M - us corporation assignees hold 55% of class grants (83 of 150). Figures describe granted US utility patents in this CPC subclass, not current investment or legal strength.

Leader's share
3.0%

17 of 568 grants

Top three share
6.2%

of the class's recorded grants

Lead over #2
5

more grants than 8 Rivers Capital, LLC

Where F23M sits inside F23

Among 12 subclasses in F23 (Combustion APPARATUS; Combustion Processes), F23M ranks #9 and holds 3.7% of the parent class's 15,279 recorded grants. Sibling chips below are the other subclasses in the same parent class, not the nationwide volume/lead-share peers further down.

F23R 4,138 F23D 2,623 F23N 1,763 F23C 1,571 F23J 1,082 F23G 1,073 F23L 922 F23K 754

Rising assignees active in F23M

Company-wide grant multiples (2022–2024 vs 2019–2021) among assignees with ≥5 patents in this subclass. Growth is company-wide; class patent counts are subclass-specific.

  1. #1 8 Rivers Capital, LLC 1.35x 31 → 42 company-wide · 12 in F23M
  2. #2 Brand Shared Services LLC 1.00x 8 → 8 company-wide · 6 in F23M
  3. #3 Rinnai Corporation 0.54x 50 → 27 company-wide · 6 in F23M
  4. #4 Ansaldo Energia Switzerland AG 0.07x 101 → 7 company-wide · 17 in F23M

F23M grants by year, peak 2019 (89)

US utility-patent grants per year in F23M, 2015–2025 - recent five years are down 28% versus 2015–2019.

020406080100 20152016201720182019202020212022202320242025 16

Who leads F23M?

The 12 most active assignees in Casings, Linings, Walls OR Doors Specially Adapted FOR Combustion Chambers, e.g. FIREBRIDGES; Devices FOR Deflecting AIR, Flames OR Combustion Products IN Combustion CHAMBERS; Safety Arrangements Specially Adapted FOR Combustion APPARATUS; Details OF Combustion Chambers, NOT Otherwise Provided FOR - wider bars mean more grants

patents

What this shows General Electric is the most active filer in F23M, holding 45 of the 568 patents in this class. Concentration at the top signals how contestable this technology area is for new entrants.

Source USPTO PatentsView, granted utility patents As of 2015–2025 grant years
View data table
Top patent holders in CPC subclass F23M
Rank Company Patents in F23M
#1 Ansaldo Energia Switzerland AG 17
#2 8 Rivers Capital, LLC 12
#3 Rinnai Corporation 6
#4 Ansaldo Energia IP UK Limited 6
#5 Brand Shared Services LLC 6
#6 Blasch Precision Ceramics, Inc. 6
#7 Ener-Core Power, Inc. 5
#8 Clearsign Combustion Corporation 4
#9 ClearSign Technologies Corporation 4
#10 Palmer Labs, LLC 4
#11 EBERSPÄCHER Climate Control Systems GMBH 3
#12 Total Raffinage Chimie 3
#13 OCV Intellectual Capital, LLC 3
#14 Fosbel, Inc. 3
#15 TPS IP, LLC 3
#16 Rolls-Royce High Temperature Composites, Inc. 2
#17 Refractory Intellectual Property GMBH & Co. KG 2
#18 Eltek S.p.A. 2
#19 Paul Wurth S.A. 2
#20 Ensyn Renewables, Inc. 2

Footprint here vs. claim strategy

Each dot is a leading F23M assignee, placed by how many patents it holds in this class (horizontal) against its company-wide average claims per patent (vertical) - a read on whether the class is led by broad-but-shallow filers or focused deep-claim players.

Top 14 F23M assignees by class footprint. Bubble size = patents in F23M. Source: USPTO PatentsView (claim depth is company-wide across all classes). Scatter plot of 14 data points (bubble-sized by third dimension). 010203040 05101520 Patents in F23M Avg claims / patent (company-wide) Ansaldo Energia…8 Rivers CapitalRinnaiAnsaldo Energia Ip UkBrand Shared ServicesBlasch Precision…Ener-core PowerClearsign CombustionClearsignPalmer LabsEberspÄCher Climate…Total Raffinage ChimieOcv Intellectual…Fosbel
Top 14 F23M assignees by class footprint. Bubble size = patents in F23M. Source: USPTO PatentsView (claim depth is company-wide across all classes).

Classes near F23M's 568-grant footprint

Nationwide nearest neighbors for F23M (#526 of 670 by volume ; lead share 7.9%) - not the F23 parent-class siblings above.

Nearest by grant volume

B41N 568 B64B 560 B60M 559 B63J 559

Nearest by lead-assignee share

F02F 7.9% B23F 7.9% G09F 7.9% B60H 8.0%

Questions about F23M

Which company holds the most patents in F23M?
General Electric Company leads F23M with 45 patents (3.0% of the subclass). By PatentsView assignee type, us corporations account for 55% of class grants.
Which F23M assignees grew fastest recently?
Among assignees with ≥5 grants in F23M, 8 Rivers Capital, LLC shows the highest company-wide grant multiple (1.35x: 31 grants in 2019–2021 → 42 in 2022–2024) while holding 12 patents in this subclass. Growth is company-wide, not class-only.
How does F23M compare inside parent class F23?
Inside F23 (Combustion APPARATUS; Combustion Processes), F23M ranks #9 of 12 subclasses by grant volume and holds 3.7% of the parent class total. The largest sibling is F23R (4,138 grants).

What to do with this data

F23M in context - here's where to go next.

  • Ansaldo Energia Switzerland AG leads F23M with 17 grants in this class. See full portfolio
  • F23M ranks #526 of 670 by grant volume among all tracked CPC technology areas. See the ranking
  • Inside parent class F23, the largest sibling subclass is F23R with 4,138 grants. Explore F23R

Figures reflect USPTO PatentsView grant data through 2026-05-15; pending applications not yet granted are not counted.

Methodology - F23M figures are USPTO PatentsView granted-utility totals for this subclass (568 grants in the tracked window).

Every figure on PlainPatent is rendered directly from USPTO source data, no number is typed in by an editor. This page draws directly on USPTO source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.