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 2008 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.orgJ2263 DEC2008 SURFACEVEHICLERECOMMENDEDPRACTICEIssued 1996-10Revised 2008-12 Superseding J2263 OCT1996 Road Load Measurement Using Onboard Anemometry and Coastdown Techniques RATIONALEThis revision updates units and in
5、troduces minor procedural refinements and formatting. 1. SCOPE This SAE Recommended Practice establishes a procedure for determination of vehicle road load force for speeds between 115 and 15 km/h (71.5 and 9.3 mi/h). It employs the coastdown method and applies to vehicles designed for on-road opera
6、tion. The final result is a model of road load force (as a function of speed) during operation on a dry, level road under reference conditions of 20 C (68 F), 98.21 kPa (29.00 in-Hg), no wind, no precipitation, and the transmission in neutral.1.1 Background This document supplements SAE J1263 FEB96.
7、 SAE J1263 remains an alternative method for evaluating vehicle road load force during low wind conditions. This procedure incorporates recent advances in test equipment and data analysis; it defines vehicle road load force over an extended speed interval. Major changes are inclusion of real time an
8、emometry to measure and compensate for wind conditions directly in front of the vehicle and use of a three term equation to model road force over a 115 to 15 km/h (71.5 to 9.3 mi/h) speed range. (The previous procedure relied on average wind conditions measured at distances up to several kilometers
9、from the vehicle. Also, road load force was modeled by a two term equation and was, typically, simulated on a hydrokinetic dynamometer capable of being adjusted to reproduce this force at only one speed; performance at other speeds was a function of dynamometer characteristics.) In addition, this pr
10、ocedure specifically discusses and authorizes “split” coastdown runs which must be used when the test track is too short to allow a complete coastdown run due to the vehicles performance, weight, or road load force characteristics. 2. REFERENCES 2.1 Applicable Publication The following publication f
11、orms a part of this specification to the extent specified herein. Unless otherwise indicated, the latest issue of SAE publications shall apply. SAE J2263 Revised DEC2008 - 2 -2.1.1 SAE Publication Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323
12、(inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org.SAE J1263 Road Load Measurement and Dynamometer Simulation Using Coastdown Techniques 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
13、SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org.SAE Paper 720099 The Determination of Vehicle Drag Contribution from Coast-Down Test, R. A. White and H. H. Korst
14、 SAE Paper 760106 Test Procedures for the Evaluation of Aerodynamic Drag on Full-Scale Vehicles in Windy Environments, W. H. Walston, F. T. Buckley, Jr., and C. H. Marks SAE Paper 760153 Tire Rolling Resistance Measurements from Coast-Down Tests, B. Dayman, Jr. SAE Paper 760850 Analysis of Coast-Dow
15、n Data to Access Aerodynamic Drag Reduction on Full-Scale Tractor-Trailer Trucks in Windy Environments, F. T. Buckley, Jr., C. H. Marks, W. H. Walston, Jr. SAE Paper 770844 Prediction of Dynamometer Power Absorption to Simulate Light Duty Truck Road Load, G. D. ThompsonSAE Paper 780255 Tire Rolling
16、ResistanceA Speed Dependent Contribution, J. R. Smith, J. C. Tracy, and D. S. PotterSAE Paper 780334 The Analytical Basis of Automobile Coastdown Testing, T. P. Yasin SAE Paper 780337 Realistic Effects of Winds on the Aerodynamics Resistance of Automobiles, B. Dayman, Jr.SAE Paper 940420 A Detailed
17、Drag Study Using the Coastdown Method, M. A. Passmore and G. M. Le Good SAE Paper 950626 ABCDAn Improved Coast Down Test and Analysis Method, F. T. Buckley, Jr. SAE Paper 970269 Determination of Coastdown Mechanical Loss Ambient Correction Factors for Use with SAE J2263 Road Tests, R. W. Andrews and
18、 D. J. Pruess 2.2.2 ISO Publication Available from ANSI, 25 West 43rd Street, New York, NY 10036-8002, Tel: 212-642-4900, www.ansi.org.ISO/DIS 10521:1991-07-31 Motor vehicle road loadDetermination under reference atmospheric conditions and reproduction on chassis dynamometer 2.2.3 Other Publication
19、Japan TRIAS 23-4 1999 SAE J2263 Revised DEC2008 - 3 -2.2.4 Sample Program A working sample program is furnished as a proposed method of following this document. The full executable program, sample data, instructions and the underlaying Visual Basic code is furnished and can be obtained by contacting
20、 Carl Paulina, paulina.carlepa.gov, at the US Environmental Protection Agency in Ann Arbor, Michigan. 3. DEFINITIONS 3.1 Constrained Analysis The vehicles frontal area and aerodynamic drag coefficient have been independently determined and those values will be used in the equation of motion. 3.2 Dri
21、veline The rotating components of a vehicle mechanically connected to the driving wheels when the transmission is in neutral gear. This includes the brake disks/drums, driveshafts, differential, propeller shaft, transmission output shaft, and some components within the transmission. 3.3 Effective Ve
22、hicle Mass The sum of the vehicle 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 components that rotate with the wheels is expressed as additional “linear” mass. For passenger cars without dual
23、 drive tires (or other driveline components which are likely to increase real rotational inertia to greater than 1.5% per axle) and 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 Mec
24、hanical Drag The force opposing vehicle movement due to tire rolling resistance and friction in the driveline and non-drive axle components.3.6 Road Load Force The total force encountered by a vehicle by reason of motion on a level, smooth surface; it includes aerodynamic and mechanical drag compone
25、nts and is expressed as a function of vehicle speed. 3.7 Test Mass The mass of the vehicle at the conclusion of the test; including driver, instrument operator (if any), and all instrumentation.SAE J2263 Revised DEC2008 - 4 -4. SYMBOLS See Table 1. TABLE 1 - SYMBOLS Symbol Units Description A m2fron
26、tal area a0andeg-ncoefficients for aerodynamic drag, as a function of yaw angle AmN coefficient of mechanical drag BmN/(km/h) coefficient of mechanical drag CmN/(km/h)2coefficient of mechanical drag Baro kPa barometric pressure Cd(Y) coefficient of aerodynamic drag at yaw angle Y D N drag DaeroN aer
27、odynamic drag scaler in direction of motion DfN front axle drag (including driveline) DgravN gravitational drag DmechN mechanical drag scaler in direction of motion DrN rear axle drag (including driveline) DtireN tire rolling resistance scaler in direction of motion (dV/dt) ms-2acceleration g ms-2gr
28、avitational constant 9.80665 m/s2(dh/ds) sine of slope M kg mass of vehicle Mekg effective vehicle mass (including rotating components) kg/m3air density t s time T C temperature V km/h vehicle velocity Vrkm/h apparent wind speed relative to vehicle Y deg yaw angle of apparent wind relative to direct
29、ion of vehicle travelW N Weight 5. INSTRUMENTATION 5.1 Calibration All instrumentation shall be calibrated. 5.2 Time (Elapsed) time shall be measured to an accuracy of 0.001 s and shall be recorded to a resolution of 0.01 s. 5.3 Vehicle Speed Vehicle speed shall be measured to an accuracy of 0.2 km/
30、h (0.1 mi/h) and shall be recorded to a resolution of 0.2 km/h (0.1 mi/h). SAE J2263 Revised DEC2008 - 5 -5.4 Relative Wind Speed Relative wind speed may be measured at the approximate mid-point of the vehicles frontal cross section and approximately 2 m in front of it. Relative wind speed shall be
31、measured to an accuracy of 1 km/h (0.6 mph) and shall be recorded to a resolution of 1 km/h (0.6 mi/h). Calibration of the anemometer shall include corrections for vehicle “blockage.” (This is not the only possible measurement location. Caution must be used to determine the wind velocity correction
32、factor at the exact measurement location.) 5.5 Relative Wind Direction (Yaw) Wind direction relative to the direction of vehicle travel may be measured at the approximate mid-point of the vehicles cross section and approximately 2 m in front of it. Relative wind direction shall be measured to an acc
33、uracy of 3 degrees and shall be recorded to a resolution of 1 degree, the “dead band” of the instrument shall not exceed 10 degrees and shall be directed toward the rear of the vehicle. Calibration of the instrument shall include corrections for vehicle “blockage.” (This is not the only position tha
34、t can be used. Caution must be used to determine the yaw angle measured versus actual wind angle transfer function for the exact measurement location) 5.5.1 Exception When the relative wind direction instrument is calibrated by means of operation on the vehicle undergoing the road load determination
35、, and where such calibration occurs as part of the test sequence (including pre- and post-test operation) and without removing or installing the instrument, the accuracy requirements set forth in do not apply. (Under these limitations, the calibration of the instrument to account for vehicle blockag
36、e makes an “accuracy” specification unnecessary; as long as the instrument responds the same way during calibration and testing, the needs of the procedure are satisfied.) 5.6 Ambient Temperature Resolution and accuracy of 1 C (1.8 F), true air temperature (shielded from the sun and track); temperat
37、ure shall be measured in a location such that it is not influenced by the vehicle. 5.7 Atmospheric Pressure Resolution and accuracy to 0.3 kPa (0.1 in-hg), data from a central facility weather station is acceptable. Track side pressure readings are preferred. 5.8 Tire Pressure Tire pressure shall be
38、 measured to an accuracy of 5 kPa (1 psi). 5.9 Vehicle Mass Vehicle (and axle) mass shall be measured to an accuracy of 10 kg (22 lb). For vehicles over 4000 kg (8818 lb), the accuracy requirement is 20 kg (44 lb). 6. VEHICLE PREPARATION 6.1 Break-In It is recommended that the vehicle and tires shou
39、ld have accumulated a minimum of 3500 km (2175 miles) and preferably 6500 km (4039 miles) of road service prior to testing. Tires may be broken-in using a different vehicle but under similar load conditions as the test vehicle. This is not an absolute requirement but is suggested to ensure repeatabl
40、e and representative test results. SAE J2263 Revised DEC2008 - 6 -6.2 Vehicle Check-In The test vehicle shall be identified. Any differences from the normal configuration or any mechanical malfunctions shall be described. The following information shall be recorded prior to the test: a. Vehicle desc
41、ription including make, model, model year, body style, VIN, engine, and transmission type. b. Tire size, manufacturer, tire performance code (TPC) or equivalent (if available), DOT identification number for each tire (if available), and the amount of tread on each tire. c. Aerodynamic drag coefficie
42、nt only if “constrained analysis” is to be used. d. Frontal area. e. Vehicle ride heights measured using the procedure specified by the manufacturer. Or, if no such procedure is specified, to top of the wheel well, or equivalent, for each wheel at test conditions. f. Manufacturers minimum recommende
43、d tire inflation pressure. g. Wheel bearing and brake drag for abnormal conditions. h. Confirm vehicle alignment to manufacturers mean specification and record. 6.3 Vehicle Maintenance If necessary, fluid levels shall be corrected to manufacturers specifications. 6.4 Instrumentation Any instrumentat
44、ion shall be installed on the vehicle in such a manner as to minimize effects on the operating characteristics of the vehicle. 6.5 Fuel The vehicle fuel tank should be filled. For multiple fuel tanks, only the main (largest) tank shall be filled. This is for easeof testing only and the amount may be
45、 adjusted for ballasting requirements.6.6 Tire Pressure The vehicle tires shall be inflated to the vehicle manufacturers minimum recommended inflation pressure, adjusted for changes in temperature between the tire soak area temperature at the time of inflation and the test track ambient temperature.
46、 (For normal passenger vehicle tires this correction is approximately a 1 kPa increase for each degree Celsius that the tire temperature exceeds the track ambient temperature.) The tire pressure must be set and recorded prior to moving the vehicle to avoid false readings. 6.6.1 Option Where tire tem
47、peratures are not stable or when the test is not to be run immediately after vehicle preparation, the tires shall be inflated to the manufacturers minimum recommended tire pressure plus 10%. The vehicle shall be parked near the test track area with the tires shielded from the sun for a minimum of 4
48、h. 7. TEST CONDITIONS 7.1 Temperature Ambient temperature shall be between 5 and 35 C (41 to 95 F). SAE J2263 Revised DEC2008 - 7 -7.2 Wind Average wind speed shall not exceed 35 km/h (21.7 mi/h). Wind gusts shall not exceed 50 km/h (31.3 mi/h). Average cross winds shall not exceed 15 km/h (9.3 mi/h
49、). 7.3 Fog and Precipitation Tests may not be run during fog or precipitation conditions. 7.4 Road Conditions The test road must be dry, clean, straight, smooth, be hard surfaced, not have excessive crown, and have a constant grade of no more than 0.5%. (There is no grade restriction if the grade is known as a function of position and vehicle position will be recorded, or calculated, on a real-time basis. The force due to
