Abstract
Synchronized gear shift units are present today in Manual Transmissions (MT) [1], Automated Manual Transmissions (AMT) [2] and Double Clutch Transmissions (DCT) [3], as well as in special applications of commercial vehicle transmissions and 4WD - applications. In any of these applications, but especially in the MT, the acting force and time needed to complete the synchronization are crucial parameters for shift comfort. Although shift comfort is a result of several effects, like double bumps, nibble, driveline vibrations, unlock problems etc., this paper focuses on the shift effort during synchronization as main influence. This paper introduces a new synchronization concept, the Kyowa High Performance (Hi-Per) Synchronizer "KHS" Its basic innovation is a small change to the geometry of a standard synchronizer unit, leading to a substantial amplification of the shift force acting at the synchronizer ring. As a result, the required synchronization force is minimized and the shift comfort is substantially improved at the same time. On the other hand, if the synchronization force is maintained, the shift time can be minimized. This paper provides information about the basic design along with sophisticated calculations, simulation and test bench results at all important working conditions. The research also concentrates on suitable friction materials under realistic conditions. The "KHS" is therefore able to provide improved comfort and minimized shift effort at virtually no additional costs of production.
Keywords: Shift Comfort, Synchronizers, Dynamic Simulation, Test Bench, Manual Transmission.