One assignee holds by far the largest share of the 1,621 records in scope, with a record count well above the next-ranked companies — the fifth-place assignee sits at 59 records and the tenth at 18. The top 5 assignees combined account for 64.8% of all records, and the top 10 reach 77.1%, so ownership in this field is concentrated rather than spread evenly across many filers. Anyone assessing risk in this space should start with the leading few portfolios rather than treating the field as fragmented.

Filing activity peaked in 2019 at 156 records and has declined since, falling from 133 in 2021 to 39 in 2024 — a -71% drop over that three-year span, using 2024 as the last year the data can treat as complete. Figures for 2025 and 2026 are still incomplete because publication typically lags filing by around 18 months, so those most recent years will rise as more records publish. On the evidence available, the trend through 2024 is a genuine pullback from the 2019 peak rather than a plateau.

US11976889B2, assigned to Danfoss and published in 2024, claims a plate heat exchanger where the gasket groove itself carries a reinforcing pattern — specifically a first recess and a second recess at different levels running lengthwise along the groove, on top of the groove’s base level. It is a detail-level claim on gasket groove geometry rather than a claim on the overall plate stack or apparatus architecture. For anyone drafting in this area, it is a useful marker of how current claims are being drawn tightly around groove reinforcement rather than broader plate or gasket material innovations.