In this work, a novel cam-based air hybrid system is proposed. Leveraging recent advancements in variable valve actuation technologies, the proposed system uses cam switching to switch between 4-stroke and 2-stroke modes and cam phasing to vary event timing. This system does not provide variable lift and duration, however, it achieves air displacement control by straddling the valve events about the top dead center and bottom dead center piston positions. In this way, the valvetrain is able to respond to varying torque demand during driving and braking.;In addition, we extend the idea of the air hybrid to the plug-in air hybrid with 2-stage compression and expansion. The 2-stage plug-in operation gives the air hybrid a significant driving range which does not require internal combustion. Considerations are made for the plug-in system components, plug-in charging, and associated driving costs.;The cam-driven air hybrid vehicle is modeled in MATLAB/SIMULINK with detailed considerations for thermodynamics, valvetrain requirements and control, and powertrain requirements and control. The vehicle is simulated under standard driving conditions. The results of the cam-driven system are compared with those of a camless system in order to gauge the level of compromise when using a less flexible valvetrain.;As a result of the extensive modeling process, a toolbox of MATLAB functions and SIMULINK blocks was created and has been adapted for general purpose thermodynamic modeling. A detailed user guide with background theory and examples was written to accompany the library, now named ThermoBox, and has been included as a chapter in this thesis. ThermoBox has been made freely available and open-source over the Internet, in an effort to aid other researchers to quickly model their systems, and has already seen application in modeling of a Rankine cycle for waste heat recovery in heavy duty trucks and modeling of pneumatic actuators for laparoscopic surgery robotics.;(Abstract shortened by UMI.)
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