Author(s): Unai Gaztañaga

Abstract: While belt-type and toroidal continuously variable transmissions dominate the passenger-car market, both suffer from efficiency losses that widen at extreme speed ratios. A nutating-disc CVT offers an alternative traction-drive architecture with inherently high torque density and a compact axial envelope. This research presents the kinematic design and multi-body dynamics (MBD) simulation of a nutating-disc CVT sized for a 1.2 L light passenger vehicle. The mechanism uses a disc tilted at a nutation angle that varies from 8° to 22°, coupled to a Ravigneaux planetary output stage, to achieve an overall speed-ratio range of 0.4 to 1.8. A transient MBD model built in MSC ADAMS incorporated Hertzian contact mechanics, temperature-dependent traction-fluid rheology, and bearing and seal friction sub-models. Peak mechanical efficiency reached 93.1% at a speed ratio of 1.0 and remained above 88% across the central 60% of the ratio range. The dominant power-loss contributor was traction-contact slip, accounting for 38.7% of total losses, followed by bearing friction (22.4%) and oil churning (18.1%). Compared with a reference push-belt CVT of similar ratio coverage, the nutating-disc concept showed 1.8 percentage points higher average efficiency over a simulated urban drive cycle. Package volume was 18.3% smaller, and estimated mass was 11.6% lower. These simulation-based findings position the nutating-disc CVT as a promising candidate for further hardware prototyping and dynamometer validation.

DOI: https://www.doi.org/10.22271/27078205.2026.v7.i2a.83

Pages: 27-31 | Views: 148 | Downloads: 67

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