Synchronization processes and synchronizer mechanisms in manual transmissions

Abstract

The transmission system is one of the main parts that determines the behavior, power and fuel economy of a vehicle. Transmission performance is usually related to gear e ciency, gear noise and gear shift comfort during gear change. Synchronizer mechanisms allow gear changing in a smooth way, noiseless and without vibrations, both for the durability of the transmission and the comfort for the users. As a consequence, it is aimed an improvement of the dynamic shift quality, by reducing shifting time and e ort, especially in heavy truck applications. This Master's Thesis project deals with a study of the synchronization processes in manual transmission gearboxes with focus on commercial vehicles. A description of the di erent types of synchronizers is given, followed by its components and how they interact with each other in order to complete the gear changing process namely the synchronization process. Then, quality factors are indenti ed and their e ect on the performance and thus synchronizer e ciency. In this project a model of the manual transmission synchronizer is developed. It is divided into eight di erent phases corresponding to di erent events in the process. Only the rst three phases have been implemented in Matlab and simulated with di erent values of some design parameters in order to analyze the reponse. The results show a good qualitative agreement with the literature.