Konceptstudie av drivmodul till bandskotare med hybriddrift

Sammanfattning: BAE Systems Hägglunds has a long history of producing high performance terrain tracked vehicles (mostly for military applications), and they are now aiming at developing a tracked forwarder with similar techniques.The forwarder will be of series hybrid type where a diesel engine via a generator will power the motors (one for each drive wheel). Thanks to individually controlled motors and the gentle rubber tracks, this forwarder is calculated to have a considerably higher average speed in the terrain and to be more gentle to the soil. The forwarder with a weight of 11 metric tons and a load capacity of 15 metric tons is specified to have an average working speed of 7-10 km/h, a top speed in terrain of 15 km/h and a top speed on roads of 40 km/h.This master’s thesis aims at developing a conceptual design of the forwarder’s drive module which includes electric motor, gear unit, brake and drive wheel.To investigate if the requirements can be fulfilled a study of the dimensioning loading scenarios has been carried out. The resulting needs regarding the torque has been considered in order to determine the required gear ratios for different motor options. A planetary gear unit is intended for the supply of the gear ratio between the electric motor and the drive wheel and with the results from the study of the different loading scenarios models of the motor and gear unit could be chosen as reference models in the concept generation part. The concepts were evaluated with a Pugh matrix in order to choose the most suitable one for further development. In the further development work the CAD models have been detailed and a verifying FEM analysis of the base in the design has been performed.The result is a conceptual design where the electric motor and the gear unit have been placed inside of the drive wheel and a disc brake system has been placed outside of the drive wheel. As gear unit a system with two steps has been chosen for adaption to the current demands regarding gear ratio and available geometrical space. The chosen motor is a permanent magnet synchronous motor with a peak torque of 324 Nm, a nominal torque of 172 Nm and a maximum efficiency of 94 %. This will result in a fulfillment of the requirements regarding the performance of the forwarder.