DESCRIPTION

 

       Ongoing advances in vehicle electronics, sensors and controllers have been integrated with mechanical components and have, in the aggregate, made possible increases in fuel efficiency and performance. Also made vehicles increasingly complex.

 

       The WHY and HOW of many new systems are far from obvious, even to the mechanically inclined and experienced however. This book provides a perspective of the impact of recent advances in vehicle components, systems, their interactions and effect on fuel efficiency; and discusses the operation of its primary components.

 

      The book has 2 parts:

 

      Part 1 discusses and quantifies the forces that resist the motion of a vehicle for any driving condition, the ‘road load’.  The road load defines the torque the powertrain must deliver to the drive wheels to propel the vehicle to cruise at a steady speed for that specific driving condition, or to accelerate or coast, and, depending on the efficiency of the powertrain and chassis components, the rate at which fuel will be consumed to produce that torque and power output.

 

      Part 1 also introduces the thinking process and procedures used to develop a vehicle road load map and predictions of performance.  A reality check.

 

      Part 2 discuses characteristics of powertrain, chassis systems and ancillaries that impact fuel efficiency and performance. It discusses the idiosyncrasies of the Otto, Diesel and Atkinson cycles, reciprocating cycles based on the slider-crank mechanism; their combustion processes, valve events and timing that define their torque curve and specific fuel consumption.  Also, it discusses cam phasers, variable valve lift and duration that can modify the engine torque curve, and direct fuel injection that allows higher compression ratios in gas engines.

 

      Also, matching the transmission and final drive ratios to the engine torque and speed characteristics to suit the requirements of road vehicles.

 

      Familiarity with these topics enables a discussion of electric drive, stop-start light hybrids and gas-electric hybrid vehicle powertrains, their different architectures; inherent range limitation, batteries, etc.

 

      Part 2 includes the summary of a report that identifies the relative development time and vehicle development and tooling costs associated with meeting fuel economy targets; by means of 1) improvements to spark ignition engines, 2) diesel engines and 3) electric drive and gas-electric hybrid powertrains. The report was commissioned by the National Highway Traffic Safety Administration and prepared by the National Academies of Sciences in conjunction with expert automotive engineers.

A reality check.

 

      Lastly, the composition of the roughly 240 million US Vehicle fleet, which historically replaces 6% (annually) of older vehicles in the fleet with new product.