ABSTRACT
Combustion, energy, and the IC engine The core of any modern automobile is the power train (Figure 2.1), which is a series of devices that convert chemical potential energy to kinetic energy and do the work of moving the vehicle. The power train is made up of the engine, transmission, differentials, driveshafts/half shafts, the axles, and the wheels. The engine is the device that converts chemical potential energy into kinetic energy via rotation of the crankshaft and flywheel. The transmission transmits the kinetic energy of the flywheel to the driveshaft or half shafts and exerts the greatest control over the final drive ratio, or the number of flywheel rotations per rotation of the wheels. Essentially, it facilitates smoother and quicker acceleration. In some vehicles, power is transferred from the transmission directly to half shafts and then to the wheels via the constant-velocity joints, which are a special bit of engineering that allows uninterrupted power transfer to the wheels no matter the positional state of the suspension. In other vehicles, the transmission rotates a driveshaft that sends the power to a differential gear assembly. The differential converts the kinetic energy of driveshaft rotation into rotation of the axle(s) oriented 90° with respect to the driveshaft. The rotating axle or axle half shafts then cause rotation of the wheels. We will visit chemical concepts related to the transmission and various other drivetrain components in subsequent chapters. However, in this chapter, we focus on the engine itself, the reactions and fuels it uses to generate power, and the ways that we can adjust the power output of an engine by varying the engine chemistry and combustion stoichiometry.
