Transient Power of A Vehicle P M V Subbarao Professor Mechanical Engineering Department Matching of Transient Horse to TransientCar….

Total Vehicular Resistance at Constant Velocity   AR = air resistance [N] RR = rolling resistance [N]             GR = gradient resistance [N] TR = total resistance [N]            

Urban Drive Cycle

Transient Nature of I.C. Engine

Instantaneous Engine Cylinder Volume

Generation of Primary Dynamic Forces

Inertial or Transient Forces on Vehicle Transient forces are primarily comprised of acceleration related forces where a change in velocity is required. These include: The rotational inertia requirements (FI ) and The translational mass (Fma). If rotational mass is added to a translating vehicle, it adds not only rotational inertia but also translational inertia.

Inertial Resistance of A Vehicle where: FIR = inertia resistance [N]         meff-vehicle = Vehicle mass + Equivalent mass of rotating parts [kg] mvehicle = Vehicle mass [kg] meq = Equivalent mass of rotating parts [kg] a = car acceleration [m/s2], (from 0 to 100 km/h in: 6 s (4.63 m/s2), 18 s (1.543 m/s2))

Equivalent Mass of Rotating Parts Torque due to any rotating part (ex. Wheel) = angular acceleration k = radius of gyration Typical Distribution of Polar Inertia : wheels and axles = 78% , propeller shaft = 1.5%, Engine = 6%, Flywheel and clutch =14.5%  

Equivalent Mass of All Rotating Parts Therefore the equivalent mass of all rotational parts including losses is represented as:

Required Torque & Power at Wheels InstantaneousTractive Effort demanded by a vehicle):

Model for Prediction of Instantaneous Fuel Consumption & Emissions Vehicle Resistance Model

Engine Model

Multi Cylinder Engine Torque

Pune Urban Drive Cycle

Engine RPM during Urban Driving Cycle Time, sec

MPFI-SI Engine Fuel Consumption

If Engine Idles during Breaking

Fuel Savings due to Idling Logic MECH 435

Idling Engine During Braking : Fuel Consumption

Engine Model

First Law Analysis: USUF FUEL A I R SI Engine CI Engine Intake Process:

Current SI Engine & Future CI Engine A I R FUEL Current CI Engine & Future SI Engine