Topological design of parallel hybrid transmission with electric torque support

In the last years hybrid Transmissions have spread worldwide in the automotive industry due to their excellent power performance and good fuel economy. The design of parallel hybrid automatic manual transmission (AMT) with electric torque support using one electric motor is a good solution of obtaining high transmission efficiency and low manufacturing cost. The gear pairs between the combustion engine (CE) shaft and electric motor (EM) shaft are assigned to form the new architecture of three degrees of freedom (DOFs) AMT with electric torque support, which provides several CE gears ratios and several EM gears ratios. All theoretical layouts of parallel hybrid AMT with three shafts are presented and classified into four types. And the synthesis of the gear ratios sequence is developed to satisfy power shifting. The gear ratios can be divided into direct gear ratio and generated gear ratio. The ratio design of generated gear is dependent on the ratio of the direct gears, so the design of gear ratio can be transformed into the solution of over-determined nonlinear equations. An algorithm of minimax solution for over-determined nonlinear equations is presented to design and evaluate gear ratios. The three-DOF three-shaft AMT with electric torque support are designed to obtain seven CE gear ratios. This paper helps to further the understanding of the systematic design of parallel hybrid AMT with electric torque support.