Fuel Efficient Engines Engine Technologies and how they affect our economy in terms of fuel conservation and ecology

How do we define efficiency? Definition How do we define efficiency? In terms of fuel economy in km/L or L/100 km for cars and trucks In terms of load carrying capacity for commercial vehicles In terms of bsfc for other engines In terms of low emissions for all engines

Main Technologies available today To improve Efficiency Variable Valve Timing and Lift, Cylinder deactivation, Turbochargers and Superchargers, Integrated Starter and Generator Systems, Direct or Indirect Fuel Injection with Turbo-charging/Supercharging, Charge Stratification, HCCI

Variable Valve Timing and Lift Also called Variable Valve actuation, variable cam timing, Variable Valve Timing (VVT) Variable-valve Timing-and-lift Electronic Control (VTEC)®

Cylinder deactivation Some refer to it as Variable Displacement or Displacement on Demand or Multiple Displacement System It was first introduced by GM in the 1980s In 2003 Cadillac built a V16 1000hp engine of size 13.6L. It could run on 8 or even on 4 cylinders “on demand” to give economy. A GM V-6 could run on 3 cylinders at light load to improve fuel economy by 6-8% In 2004, Honda introduced an i-VTEC V6 (an update of the venerable J-series), but in this case, i-VTEC had nothing to do with cam phasing. Instead, i-VTEC referred to Honda's cylinder deactivation technology, which closes the valves on one bank of (3) cylinders during light load and low speed (below 80 mph) operation.

Supercharging and Turbo-charging Requires reduction in compression ratio or change in spark timing to reduce knock. When provided with after cooling, the reduction in compression ratio is less Either increased power can be obtained with the same size engine or it is possible to reduce the size for the same power and hence reduce fuel consumption

Integrated Starter/generator Systems These systems automatically turn the engine off when the vehicle comes to a stop and restart it instantaneously when the accelerator is pressed so that fuel isn't wasted for idling. In addition, regenerative braking is often used to convert mechanical energy lost in braking into electricity, which is stored in a battery and used to power the automatic starter.

Fuel Injection Applied to the S.I.Engine There are three possible locations: 1. Inlet Manifold. 2. Inlet Port. 3. Direct Cylinder.

Direct Cylinder Injection Fuel is injected directly into the cylinder Possible to operate ultra lean – one report claims 65:1 air-fuel ratio under normal running – stratified charge Stoichiometric operation under normal running - homogeneous charge Rich mixture for full power operation – homogeneous charge

Semi-direct Injection or Port Injection Injectors Positioned in Each Induction Manifold Branch Just in Front of Inlet Port Injection at Low Pressure (2-6 Bar) Need Not Be Synchronized With Engine Induction Cycle Fuel Can Be Discharged Simultaneously to Each Induction Pipe Where it is Mixed and Stored Until Inlet Valve Opens Need Not Be Timed – Requires Low Discharge Pressures – Injectors Not Exposed to Combustion Products so Complexity Reduced – Less Cost

Charge Stratification

THE HCCI ENGINE