In this corpus, filing activity concentrates around a small group of Japanese OEMs and their dedicated transmission suppliers, most notably the Nissan-Jatco pairing, which co-assigns 137 shared families, and Toyota's related corporate entities at 112. Aisin AW, Honda, Subaru, Torotrak and NSK also appear as active filers. The pattern reflects how CVT development has historically been organised around tight OEM-supplier relationships rather than independent component makers.

No. Filings peaked at 90 in 2018 and had fallen to 6 by the 2022 midpoint, with near-zero counts in the most recent tracked years. Some of that recent drop reflects the roughly 18-month lag between filing and publication, so the very latest years will always look artificially low. But the multi-year decline from the 2018 peak is real and suggests the core mechanical claim space is heavily occupied rather than expanding.

Belt and pulley CVT claims, including hydraulic actuator designs like US8029395B2 from Subaru, form the bulk of the F16H gearing cluster and dominate current commercial designs. Toroidal variator patents, such as US6045481A and US6931316B2, are older and carry very high citation counts, showing they were foundational to slip-control and ratio-control methods even though toroidal CVTs saw less commercial adoption than belt designs. Both approaches sit inside the same IPC subclasses, so a search by IPC code alone will not separate them.

The thinnest claim density relative to the mechanical core sits in software-defined ratio control tied to hybrid drivetrains (B60W, 428 records against a corpus of 2,290), chain-CVT-specific actuator geometries, and toroidal designs adapted for electrified powertrains. These are areas where the underlying mechanical patents are dense but the control-integration and electrification overlap is comparatively under-claimed, making them worth a freedom-to-operate check before assuming the space is closed.

US8029395B2, assigned to Subaru and granted in 2011, claims a specific hydraulic actuator architecture for belt-type CVTs: a movable sheave with a first cylinder, a drum with two portions, and two plungers that together form first and second hydraulic chambers. It is a mechanical design for reducing manufacturing cost while keeping smooth actuation, not a method claim over hydraulic actuation generally. Anyone designing a belt CVT actuator with a similarly structured dual-chamber, dual-plunger arrangement should review its specific claim language rather than assume the general concept of hydraulic pulley actuation is blocked.