Development of tolerance-based design optimization technology for the horizontal magnetized structure of acoustic vehicle alerting system

Noise generation for helping people recognize the driving status of vehicles at low speeds has become legalized with the spread of electric and hydrogen vehicles, which requires a virtual engine sound generator. Furthermore, these generators require a slim design for installation in the vehicle. Therefore, in this study, in order to examine the relationship between the design parameters of the horizontal magnetized structure for maintaining the electromagnetic force performance and minimizing the actuator thickness, an independent analysis using a single variable and an investigation of the characteristic change due to multiple variables were sequentially performed. With respect to factor analysis of multiple variables, a screening analysis for performance improvement factors and an impact analysis for effects were conducted using a full factorial design. To verify the nonlinear characteristics, the significance of the curvature effect was verified by adding a central point to the analytical points of view, and a nonlinear regression model of the prediction model was derived using the face-centered central composite design of the response surface methodology. Five design parameters were found to influence the electromagnetic force performance and thickness minimization in the horizontal magnetized structure: magnet thickness, magnet adapter thickness, plate thickness, yoke position, and yoke thickness. Furthermore, when the tolerance management level of the design in the manufacturing process of each design parameter was limited to 3σ, the confidence level was predicted to increase to the range of 98.69–99.73% for the electromagnetic force performance and to the range of 97.64–99.73% for thickness minimization