Road Load Power Equations

Application of Road Load Power Equations

ME480/588

Road Load Power

Vehicle Modeling ProjectEquinox Data

The frontal area of the vehicle is 2.686 m2The drag coefficient is 0.417The mass is 1713 kg

Assume the tires are Michelin PAX Challenge X 235-710 R460A on 225-460A Rim, with a radius of 355 mm and a coefficient of rolling resistance, f = 0.00675.

Fiat Transmission Data

Transmission Gear, Gear Ratio, Drivetrain Efficiency, Gamma

1, 3.917, 0.90, 0.52, 2.040, 0.91, 0.33, 1.321, 0.93, 0.14, 0.954, 0.97, 0.055, 0.755, 0.98, 0.036, 0.626, 0.98, .025Final Drive Ratio = 5.545

Ballard Integrated Transaxle

Rear Transaxle Final Drive Ratio = 10.10, Drivetrain Efficiency = 0.98

Assume standard atmospheric pressure and temperature.

Constant Speed Application

=0=0

Drive Cycle Application

Federal Urban Driving Schedule (FUDS)

Highway Fuel Economy Test (HFET)

US06

SC03

Cold temperature test- FUDS at 20F ambient

EPA Fuel Economy Rating Tests

EPA Test Conditions

Federal Urban Driving Schedule

Simulates urban driving in Los Angeles in 1975

Highway Fuel Economy Test

Simulates highway driving in Los Angeles in 1975

US06

Simulates high speed and aggressive driving

SC03

Run with A/C on and 95ambient temperature

Combined Fuel Economy Rating

Old method thru 2007-55% FUDS, 45% HFET

New Method- 40 CFR 600.114-08 - Vehicle-specific 5-cycle fuel economy and carbon-related exhaust emission calculations.

Federal Urban Driving Schedule (FUDS)Time Speedsec mph0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.010 0.011 0.012 0.013 0.014 0.015 0.016 0.017 0.018 0.019 0.020 0.021 3.022 5.923 8.624 11.525 14.326 16.927 17.328 18.129 20.730 21.731 22.432 22.533 22.1

=0

Highway Fuel Economy Test (HFET)Time Speedsecs mph0 01 02 03 24 4.95 8.16 11.37 14.58 17.39 19.610 21.811 2412 25.813 27.114 2815 2916 3017 30.718 31.519 32.220 32.921 33.522 34.123 34.624 34.925 35.126 35.727 35.928 35.829 35.330 34.931 34.532 34.633 34.8

=0

Acceleration Application

known calculate

Given a known Pdw-what is the maximum acceleration as a function of V?





=0

Engine Data

Motor Data

Through-the-Road





Matlab ProjectEquinox Data

The frontal area of the vehicle is 2.686 m2The drag coefficient is 0.417The mass is 1713 kg

Assume the tires are Michelin PAX Challenge X 235-710 R460A on 225-460A Rim, with a radius of 355 mm and a coefficient of rolling resistance, f = 0.00675.

Fiat Transmission Data





Assume standard atmospheric pressure and temperature.

Matlab Project

For an Equinox with two 150-lbm passengers aboard, perform the following analyses using MATLAB:

1. Prepare a graph that shows the "engine" power (kw) required to propel the Equinox along level ground as a function of vehicle speed (km/hr). Show the total power and the various contributors (drivetrain losses, aerodynamics power, rolling resistance) to the power for vehicle speeds ranging from 30 to 100 km/hr. For this analysis, use the drivetrain properties for 5th gear.

Constant Speed Application

=0=0

Matlab Project

2. Prepare a graph showing the drive wheel power (kw) required to propel the Equinox on the FUDS and the HFET driving schedules. The FUDS and HFET cycles are available in the Course Materials section.

a. Use the simplifying assumption that the equivalent mass of the rotating parts is 6% of the static mass.

Federal Urban Driving Schedule (FUDS)Time Speedsec mph0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.010 0.011 0.012 0.013 0.014 0.015 0.016 0.017 0.018 0.019 0.020 0.021 3.022 5.923 8.624 11.525 14.326 16.927 17.328 18.129 20.730 21.731 22.432 22.533 22.1

=0

Highway Fuel Economy Test (HFET)Time Speedsecs mph0 01 02 03 24 4.95 8.16 11.37 14.58 17.39 19.610 21.811 2412 25.813 27.114 2815 2916 3017 30.718 31.519 32.220 32.921 33.522 34.123 34.624 34.925 35.126 35.727 35.928 35.829 35.330 34.931 34.532 34.633 34.8

=0

Matlab Project

2. Prepare a graph showing the drive wheel power (kw) required to propel the Equinox on the FUDS and the HFET driving schedules. The FUDS and HFET cycles are available in the Course Materials section.

b. Use the following simplified shift schedule:Shift Speed (mph)1-2 9.572-3 18.373-4 28.384-5 39.305-6 49.652-1 5.7433-2 11.024-3 17.025-4 23.586-5 29.79

Up-shifting Gears

Criteria for shifting from 12

Vehicle is accelerating

AND

Shifting threshold has been passed

and

Down-shifting Gears

Criteria for shifting from 21

Vehicle is decelerating

AND

Shifting threshold has been passed

and

Shifting

Note: has different values for each transmission gear

Matlab Project

3. Calculate the acceleration potential of the hybrid Equinox, i.e., determine the minimum time for 1000 rpm in 1st gear to a distance of 1/4 mile and prepare a graph showing the vehicle speed versus time. Prepare a graph showing the maximum acceleration versus vehicle speed for each transmission gear, for an engine speed range of 1000 rpm to 4500 rpm, to determine the optimum transmission shift points.

Engine Data

Motor Data

Through-the-Road





Shifting for Max Acceleration

Dont use the provided shift schedule

Shifting occurs at crossing points from a vs. V plot

Shifting occurs at constant vehicle speed Shifting is instantaneous

Engine Speed changes when shift occurs

Motor Speed doesnt change when shift occurs

Front powertrain efficiency changes with gear shifts

changes with gear shifts

Rear powertrain efficiency doesnt change with gear shifts

Speed vs Time

Distance vs Time

Matlab Project

Deliverables:Submit a brief report containing problem statement, summary of engine data and vehicle parameters, graphs, MATLAB code and discussion of results.

Due Date- Thursday September 24

Documents

Road Load Power Equations