1、_SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising theref
2、rom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2010 SAE International All rights reserved. No part of this publication ma
3、y be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA)
4、Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J1263_201003SURFACEVEHICLERECOMMENDEDPRACTICEJ1263 MAR2010 Issued 1979-06Revised 2010-03 Supersedi
5、ng J1263 JAN2009 Road Load Measurement and Dynamometer Simulation Using Coastdown Techniques RATIONALEThe value change and proper unit formatting correct oversights in the original document.FOREWORDThis procedure was originally designed in the English units system and has been converted to the metri
6、c (MKS) system of units. This will explain the somewhat awkward values used in this procedure. 1. SCOPE This procedure covers measurement of vehicle road load on a dry, straight, level road at speeds less than 113 km/h (70 mi/h). 1.1 Purpose This SAE Recommended Practice provides uniform testing pro
7、cedures for measuring the road load force on a vehicle as a function of vehicle velocity and for simulation of that road load force at 80 km/h (50 mi/h) on a hydrokinetic chassis dynamometer. For application to electric dynamometers, refer to SAE J2263. 2. REFERENCES 2.1 Applicable Publications The
8、following publications form a part of this specification to the extent specified herein. Unless otherwise specified, the latest issue of SAE publications shall apply. 2.1.1 SAE Publication Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside
9、USA and Canada) or 724-776-4970 (outside USA), www.sae.org.SAE J1100 Motor Vehicle Dimensions SAE J1263 Revised MAR2010 - 2 -2.1.2 Federal Regulations Available from the Superintendent of Documents, U.S. Government Printing Office, Mail Stop: SSOP, Washington, DC 20402-9320.Code of Federal Regulatio
10、ns, 40 CFR 600, Appendix I 2.2 Related Publications The following publications are provided for information purposes only and are not a required part of this document. 2.2.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (insid
11、e USA and Canada) or 724-776-4970 (outside USA), www.sae.org.R. A. White and h. h. Korst, “The Determination of Vehicle Drag Contribution from Coast-Down Test,“ SAE Paper 720099, 1972T. P. Yasin, “The Analytical Basis of Automobile Coastdown Testing,“ SAE Paper 780334, 1978 B. Dayman, Jr., “Tire Rol
12、ling Resistance Measurements from Coast-Down Tests,“ SAE Paper 760153, 1976 G. D. Thompson, “Prediction of Dynamometer Power Absorption to Simulate Light Duty Truck Road Load,“ SAE Paper 770844, 1977 J. R. Smith, J. C. Tracy, and D. s. Potter, “Tire Rolling ResistanceA Speed Dependent Contribution,“
13、 SAE Paper 780255, 1978 B. Dayman, Jr., “Realistic Effects of Winds on the Aerodynamics Resistance of Automobiles,“ SAE Paper 780337, 1978 3. DEFINITIONS 3.1 Test Weight Is the weight of the vehicle as tested; including driver, operator (if necessary), and all instrumentation. 3.2 Test Mass Is the m
14、ass of the vehicle as tested; including driver, operator (if necessary), and all instrumentation. 3.3 Effective Mass Is equal to the sum of the test mass and the effective mass of rotating components. 3.4 Effective Mass of Rotating Components The rotational inertia of driveline and non-drive axle co
15、mponents that rotate with the wheels, expressed as additional “linear mass“. For passenger cars without dual drive tires, if the actual effective mass of rotating components is unknown, the effective mass of all rotating components may be estimated as 3.0% of the vehicle test mass. 3.5 Frontal Area
16、Is the area of the orthogonal projection of the vehicle including tires and suspension components onto a plane perpendicular to the longitudinal axis of the vehicle. SAE J1263 Revised MAR2010 - 3 -4. SYMBOLS a = Slope of the actual dynamometer horsepower1/t curve (kW-s or hp-s) A = Vehicle frontal a
17、rea (see 8.6) (m2or ft2)b = Zero intercept of the actual dynamometer horsepower1/ t curve (kW or hp) CD= Aerodynamic drag coefficient (dimensionless) CD= Aerodynamic drag coefficient for nonzero yaw (dimensionless) (see 10.2)CDY= Crosswind aerodynamic drag coefficient (dimensionless) D = Denominator
18、 of expressions to determine a and b from vehicle-dynamometer coastdown data Dtot= Total drag force (N or lb) f0, f2= Coefficients of the zeroth and second order terms (respectively) in the road load force equation (N or lb and N/km/h2 or lb/mph2)f0, f2= Coefficients of the zeroth and second order t
19、erms (respectively) in the road load force equation (N or lb and N/kmh2 or lb/mph2) corrected to standard conditions g = Acceleration of gravity 9.81 m/s2or 32.174 ft/s2l = Moment of inertia of tire, wheel, and brake rotor or drum kg-m2or ft-lb-s2IW = Inertia weight or equivalent weight of inertia s
20、imulation mechanism (N or lb) k = Drag coefficient dependence on yaw angle kt= Temperature coefficient of rolling resistance (C-1or F-1)M = Vehicle test mass (kg or slugs) me= Effective mass of a wheel, tire, and brake assembly (kg or slugs) MDLC= Total equivalent mass of drivetrain components (kg o
21、r slugs) MIW= Equivalent mass of dynamometer inertia simulation mechanism (IWC/g) (kg or slugs) Me= Total effective vehicle mass (kg or slugs) N = Number of data points used in Part 2 P0= Reference atmospheric pressure 736.6 mm Hg (29.00 in Hg) r = Tire rolling radius (m or ft) S = +1 or -1, dependi
22、ng on vehicle coastdown direction t0= Time (seconds) t-t0= Coastdown time interval (seconds) t = Vehicle coastdown time on the chassis dynamometer(s) T = Ambient temperature of test area (K or R) T0= Standard temperature (20 C = 293.15 K, 68 F = 527.67 R) V = Vehicle speed (km/h or mi/h) V = Vehicle
23、 velocity (km/h or mi/h) V1, V0= Final and initial speeds in the calculation of the coastdown time interval (km/h or mi/h) vx= Component of wind parallel to track (km/h or mi/h) vy= Component of wind perpendicular to track (km/h or mi/h) W = Vehicle test weight (N or lb) Ww= Weight of tire, wheel, a
24、nd brake rotor or drum (N or lb) = Coefficient of rolling resistance (dimensionless) 0= Velocity-independent coefficient of rolling resistance (dimensionless) = Velocity-dependent coefficient of rolling resistance (km/h-2or mi/h-2) = Air mass density (kg/m3or slugs/ft3) = Aerodynamic yaw angle (radi
25、ans) 5. PART 1VEHICLE ROAD LOAD MEASUREMENT 5.1 Instrumentation All instrumentation must be calibrated. 5.2 Speed Time An instrument to measure vehicle speed as a function of elapsed time is used in this procedure. The device must meet the following specifications: SAE J1263 Revised MAR2010 - 4 -a.
26、Time: 1. Accuracy 0.1% of total coastdown time interval 2. Resolution 0.1 s b. Speed: 1. Accuracy 0.4 km/h (0.25 mi/h) 2. Resolution 0.2 km/h (0.1 mi/h) 5.3 Temperature The temperature indicating devices must have a resolution of 1 C or 2 F and an accuracy of 1 C or 2 F. The sensing element must be
27、shielded from radiant heat sources. 5.4 Atmospheric Pressure A barometer with an accuracy of 0.7 kPa or 0.2 in Hg is necessary. 5.5 Wind Wind speed and direction during the test should be continuously monitored. Wind measurements should permit the determination of average longitudinal and crosswind
28、components to within 1.6 km/h (1 mi/h). 5.6 Vehicle Weight Vehicle weight should be measured to an accuracy of 5 kg (10 lb) per axle. 5.7 Tire Pressure Should be measured to an accuracy of 3 kPa (0.5 psi). 6. TEST MATERIAL 6.1 Test Vehicle The test vehicle should be uniquely described on the Vehicle
29、 Road Test Data Sheet (see Figure 1). In particular, any modifications from the normal configuration of the vehicle should be noted. 7. TEST CONDITIONS 7.1 Ambient Temperature Ambient temperatures shall be between 5 C and 35 C (41 to 95 F). Data obtained at temperatures outside this range cannot be
30、reliably adjusted to standard conditions by Section 10.5. 7.2 Fog Tests may not be run during foggy conditions. SAE J1263 Revised MAR2010 - 5 -7.3 Winds Tests may not be conducted when wind speeds average more than 16 km/h (10 mi/h) (or when peak wind speeds are more than 20 km/h 12.3 mi/h). The ave
31、rage of the component of the wind velocity perpendicular to the test road may not exceed 8 km/h (5 mi/h). 7.4 Road Conditions Roads must be dry, clean, smooth, and must not exceed 0.5% grade. In addition, the grade should be constant and the road should be straight since variations in grade or strai
32、ghtness can significantly affect results. (The road surface should be concrete or rolled asphalt (or equivalent) in good condition since rough roads can significantly affect rolling resistance.)7.5 Coastdown Speed Range The range of speeds over which the vehicle is coasted should be as long as possi
33、ble considering the length of the straightaway. The speed interval must include 80 km/h (50 mi/h) and should include the range of 100 to 40 km/h (60 to 25 mi/h). 8. VEHICLE PREPARATION 8.1 Break-In The test vehicle should have accumulated a minimum of 500 km (300 miles) prior to testing. The tires s
34、hould have accumulated a minimum of 3500 km (2175 miles) and should have at least 50% of the original tread depth remaining. In addition, if a twin roll dynamometer is to be used, the drive axle tires should have a minimum of 1 h at 80 km/h (50 mi/h) on the dynamometer rolls before conducting the dy
35、namometer road load simulation portion of this procedure. All tire break-in should be performed on the test vehicle or under load conditions similar to those imposed by the test vehicle. 8.2 Vehicle Check-In The following items should be compared to manufacturers recommendation and recorded on the V
36、ehicle Road Test Data Sheet (see Figure 1) prior to the test: a. Tire type, size, and cold inflation pressure (see 8.5) b. Wheel size, conditions, and presence of wheel covers c. Brake adjustment d. Lubricants in the drivetrain and in the nondriving wheel bearings e. Vehicle suspension heights 8.3 I
37、nstrumentation The speed-time measuring device and other necessary equipment must be installed so that they do not hinder vehicle operation or alter the operating characteristics of the vehicle. 8.4 Pretest Weight The weight of the vehicle prior to testing should be appropriate for the vehicle repre
38、sented; for example, consideration should be given to the effect of the added weight of the test instrumentation. SAE J1263 Revised MAR2010 - 6 -8.5 Tire Pressure Inflate the tires of the test vehicle to the manufacturers recommended cold inflation pressure, corrected for the temperature difference
39、(if any) between the vehicle tires and the test area. The tire pressure should be increased 1 psi for each 13 F that the vehicle preparation area temperature the test is above the test temperature or 1 kPa for each Celsius degree. Record the actual inflation pressure and preparation area temperature
40、 on the Vehicle Road Test Data Sheet (see Figure 1). FIGURE 1 - VEHICLE ROAD TEST DATA SHEET SAE J1263 Revised MAR2010 - 7 -8.6 Vehicle Frontal Area The vehicle frontal area must be known, measured, or estimated and the value recorded on the Vehicle Road Test Data Sheet (see Figure 1). The frontal a
41、rea may be estimated by the following equation: A = 0.8 (H101) x (W103) (Eq. 1) where:H101 = Body height (meters feet) measured according to SAE J1100 W103 = Body width (meters feet) measured according to SAE J1100 8.7 Vehicle Warm-Up The vehicle must be driven a minimum of 30 min at an average spee
42、d of 80 km/h (50 mi/h) immediately prior to the test. 9. COASTDOWN TEST 9.1 Alternating Directions A minimum of 10 runs are made in alternating directions. The runs must be paired for the data reduction process in order to reduce error. 9.2 Procedure The vehicle windows must be closed. At the start
43、of each run, accelerate the vehicle to a speed 8 km/h (5 mi/h) above the high point of the coastdown speed range, start the recording equipment, and shift into neutral and let the engine idle. The vehicle clutch must be engaged. At a speed less than the lower point of the coastdown speed range, stop
44、 the recording equipment, engage the transmission, and prepare for the next run. Vehicle regenerative braking shall be disabled during coastdown testing, minimizing any changes to the mechanical system (see SAE J1634). 9.3 Lane Changes While coasting, lane changes should be avoided if at all possibl
45、e. If necessary, they should be done as slowly as possible and over a distance of at least a half kilometer (a quarter mile). If such a gradual change cannot be made, abort the run. 9.4 Data to be Recorded Record the direction and number of each run (including aborted runs) in such a way that the sp
46、eed time data can be separated by run number. Record the ambient temperature and atmospheric pressure after the warm-up and after the test. Average the two values to determine the value to be used in the data reduction. The total wind and either the wind direction or the crosswind component of the t
47、otal wind must be recorded. The wind quantities should be recorded, screened for gusts exceeding the ambient condition limits in 7.3, and averaged. Record the results on the Vehicle Road Test Data Sheet (see Figure 1). 9.5 Vehicle Test Weight or Mass After the coastdown run, weigh the vehicle to det
48、ermine the vehicle test weight or mass. Include the weight of the fifth wheel, driver, and all instrumentation used. Record on the Vehicle Road Test Data Sheet (see Figure 1). SAE J1263 Revised MAR2010 - 8 -9.6 Axle Weights Measure each axle weight as in 9.5 except with the fifth wheel (if used) in
49、the operating position and off the scale. Record on the Vehicle Road Test Data Sheet (see Figure 1). 10. DATA REDUCTION This section prescribes the technique for analyzing a set of coastdown data and the correction factors employed in the determination of the coefficients of the road load force equation. These corrected coefficients are used to calculate the time required to freely
