This paper focuses on a physics-based model of a chain CVT. The study starts from kinematics of an infinitely small chain segment, and then investigates the fundamental dynamics of the chain segment. A speed-dependent continuous friction model is employed that accounts for both micro-slip and macro-slip conditions. Pulley axial dynamics is studied and is coupled with chain segment radial movement. The classical pulley deformation (Sattler's model) is included in the model. Simulation results show that pulley deformation plays an important role in defining the chain CVT dynamics. Unlike a rigid pulley, sliding angle with a deformable pulley is not a constant. Internal forces like chain tension and normal contact force are not monotonic function of angular position within the wrap. The simulation results compare well, qualitatively and quantitatively, with data published in literature and clamp force ratio (KpKs) values from dynamometer testing.

Improving automobile fuel efficiency is an important research and development effort in the automotive industry. In the transmission area, it is generally understood that optimum fuel economy can be achieved via a combination of highly efficient power transfer (gears, for example) and an ability to transmit power at an infinite number of ratios (CVT, for example). In this paper, a geared infinitely variable transmission (IVT) is analyzed for efficiency through static analysis. This IVT is based on a non-circular gear concept described in [1, 2]. This IVT consists of multiple function generators with each function generator comprising two sets of non-circular gear sets whose outputs are combined with a summing planetary gear set. Each function generator provides the desired gear ratio for only a part of the driving rotation. So, multiple function generators are combined along with multiple one-way clutches to provide an infinitely variable transmission. This paper first explains the operating principle of the geared IVT. A static analysis of the IVT powerflow is derived and it is shown that this powerflow exhibits a torque recirculation phenomenon, which is not desired. This recirculation phenomenon is expected to be present in all similarly arranged IVTs where two inputs are combined using a planetary gear set to provide infinite gear ratio capability. The efficiency of the IVT is calculated based on assumed individual component efficiency and it is shown that, owing to torque recirculation, the efficiency of this transmission may not compare well with that of current automatic transmissions for a passenger car application.

With the advent of CAE, simulation of engineering design processes is gaining rapid progresses in order to reduce design cycle time and prototype building and testing practices. An automobile drive train is a typical example whose design and acceptance of prototype is an expensive and time consuming process. Here we demonstrate how this design process can be speeded up through simulation of drive train dynamics that can match with test results; thus reducing design cycle time and gain better understanding by parameter variation during the design stages. A typical AWD (All Wheel Drive) is simulated here for torsional dynamics of the entire drive train from the engine to the wheels through torque converter, transmission gear box, transfer case, propeller shafts, differentials and axles to the four wheels. We show that the simulation results can confidently predict test values.

"Double Transition Shift" refers to the shift process in a special structured automatic transmission which employs more than one pair of clutches and brakes to perform a gear shift. Since more elements are involved during the shift process, the double transition shift algorithm is much more complicated than the traditional gearbox. Therefore, the development of the control strategy to accomplish the optimal driveability becomes a challenge for automotive control engineers.In this paper, a patented double transition transmission is studied for shifting process using a dynamic analysis and driveability control algorithm simulation. A dynamic model is developed based on multi-body dynamics theory in which all elements interactions with varies motion states and forces are considered.A simulation model of the whole vehicle and the transmission is established. Based on the parametric study, the control strategy is proposed and a well behaved driveability during the double transition shift process is achieved.

Friction Launch transmissions use a wet multi-plate clutch to replace the torque converter in an automatic transmission. The main benefit of this technology is fuel economy improvement as a result of eliminating the losses in the torque converter. By using one of the range clutches inside the transmission instead of an input clutch in place of the converter, the benefits of this integrated friction launch technology, such as reduction in mass, packaging, and cost, can be enhanced. The availability of new automatic transmissions with higher number of speeds and wider overall ratio spreads makes this technology more viable than ever before. This project focuses on control issues with the friction launch clutch which include developing robust control algorithms for launch and creep, and providing damping to the driveline, when required, and ensuring acceptable vehicle drivability. This paper describes in detail the development of vehicle launch control algorithms. Vehicle test data is presented to show that the control strategy developed in this project significantly reduces the gap between the drivability of a starting clutch vehicle and a torque converter equipped vehicle.