High-Performance Rotor Cooling with Ducted Liquid in Completely Cold-Formed Modular Motor Shaft

TL;DR

This paper introduces a novel tooth-guided liquid-cooling shaft design for electric motors that significantly enhances cooling efficiency and thermal management through optimized internal channels, improving motor performance and durability.

Contribution

The paper presents a new rotor-cooling shaft concept with cold-formed internal channels that reduces vortex formation and boosts heat transfer, outperforming conventional designs in efficiency.

Findings

Up to 110% higher cooling efficiency at low speeds

Maintains comparable pressure levels to conventional shafts

Improves thermal performance and durability of electric motors

Abstract

This paper suggests a novel rotor-cooling shaft concept for high-performance electric motors that increases the effectiveness of cooling and is yet simple and cost-effective to manufacture. We investigate the thermal performance of four shaft geometries for rotor cooling in automotive applications. The proposed tooth-guided liquid-cooling shaft design aims to solve the high churning loss of conventional cooled rotor shafts due to internal vortex formation and their still limited heat transfer. Therefore, we optimize heat transfer efficiency and pressure management by incorporating cold-formed internal channels that restrict vortex formation beyond a degree that improves heat transfer. We evaluated key performance metrics, including heat transfer rate, outlet temperature, pressure drop, and velocity profiles, under varying rotational speeds, inlet flow rates, and coolant temperatures. Computational fluid analysis demonstrates that the tooth-guided design outperforms conventional hollow shafts and achieves up to 110% higher cooling efficiency at low rotational speeds, while it maintains comparable pressure levels. These findings provide practical insight into geometry-driven thermal optimization and offer a path toward improving the performance and durability of electric motors.