Todd William Fritz

Integration of Triaxial Hall-Effect Sensor Technology for Gear Position Sensing in Commercial Vehicle Transmissions

The proliferation of microprocessor architecture onboard transmission control modules has seen sensors play a crucial role in feedback control. This paper presents a linear position sensor module with a Hall-effect element for gear position sensing in a commercial vehicle transmission. Finite-element analysis model of the sensor performance has been performed, and the model has been validated against experimental data from the sensor prototype. The significance of this paper is that a low-cost linear position sensor module has been developed with high linearity, high output resolution (37.5 μm), and high accuracy (0.25 mm) for gear position sensing. The complete sensor system is designed for ease of manufacturing and application in harsh transmission environments, such as high-temperature profiles ranging from -40 °C to +135 °C.

Gearbox Speed Sensor Design and Performance Optimization

The speed sensing applications of a gearbox demand high operational air-gaps, tight switching and timing accuracy, and excellent overall reliability. High teeth density and small-diameter helical (nonsymmetrical) teeth profiles with fine teeth pitch pose significant challenges to rotational speed sensing. For many embedded control systems, such as an automated mechanical transmission, it is critical that before the transmission control module decides whether to open or close a clutch, the speed of a shaft and the corresponding gear have to be synchronized. This requires high fidelity in the accuracy of the computed shafts speed. This paper presents a low-cost rotational speed sensor module with high output accuracy and resolution for gear speed sensing in a commercial vehicle gearbox. The sensor performance has been modeled using finite element analysis, and the model has been validated against experimental data from the sensor prototype. The complete sensor module is designed for ease of manufacturing and application in harsh transmission environments such as high temperature profiles ranging from -40°C to 125°C.