Abstract
This paper deals with a powershift automated manual transmission, i.e. an automated manual transmission with a torque gap filler, which essentially integrates, in a typical manual transmission layout, a torque gap filler assembly with the aim of reducing the torque gap that occurs during gearshifts. The torque gap filler consists of an additional mechanical link between the engine and the transmission output shaft, thus enabling the engine power to flow through this parallel path also when the launch clutch is disengaged, with clear benefits in terms of both sportiness and passenger comfort. This paper is the first part of a two-part study which, after a general description of the transmission architecture and its working principle, examines a practical implementation of the torque gap filler concept; the additional mechanical components and their integration into a traditional automated manual transmission are presented. Then, kinematic analysis and dynamic analysis of the transmission are proposed. The evolution of the transmission speeds are studied in the whole working range of the vehicle; the equations of motion are derived and used to show the effect of the torque gap filler on the torque transmitted to the wheels and consequently on the vehicle acceleration during gearshifts. The companion paper (Part 2) covers control issues and provides experimental validation.
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