Two-Position Linear Electromagnetic Gear-Shifting Actuator and the Influence of Ferromagnetic Material Proximity on Its Performance

Abstract

This paper investigates a magnet-free, two-position electromagnetic gear-shifting actuator designed for mobile machinery applications. Unlike conventional hydraulic, pneumatic, or electromechanical systems, the proposed actuator employs tangential electromagnetic forces to engage and disengage gears without permanent magnets, thereby eliminating concerns about cost, sustainability and supply chains of the rare-earth materials. A systematic design methodology is presented, starting with simplified two-coil configurations and progressing to multi-coil topologies with advanced flux-guiding strategies - resembling a linear actuator. Axisymmetric finite-element simulations are used to evaluate force characteristics, transient dynamics, and sensitivity to environmental variations. Particular emphasis is placed on the influence of surrounding ferromagnetic structures, which are shown to significantly alter the magnetic flux distribution and reduce actuation force if not properly accounted for. Case studies demonstrate that while two- and three-coil designs suffer from force sags and premature flux leakage, a multi-coil (e.g. six-coil) topology can sustain the required engagement forces in most environments, though performance degrades under full ferromagnetic enclosure. Results indicate that actuator performance strongly depends on spatial clearance from ferromagnetic components, rotor mass, and coil switching dynamics. The findings provide practical design guidelines for integrating magnet-free electromagnetic shifters into electric vehicle drivetrains, highlighting both the opportunities for sustainable materials and the challenges of flux management in constrained environments.