1、_ 6$(7HFKQLFDO6WDQGDUGV%RDUG5XOHVSURYLGHWKDW7KLVUHSRUWLVSXEOLVKHGE6$(WRDGYDQFHWKHVWDWHRIWHFKQLFDO 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 tKHUHIURPLVWKHVROHUHVSRQVL
2、ELOLWRIWKHXVHU SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2014 SAE International All rights reserved. No part of this publication may be reproduced, st
3、ored 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: +1 724-776-4970 (outside USA) Fax: 724-776-079
4、0 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J2264_201401 SURFACE VEHICLE RECOMMENDED PRACTICE J2264 JAN2014 Issued 1995-04 Revised 2014-01 Superseding J2264
5、APR1995 Chassis Dynamometer Simulation of Road Load Using Coastdown Techniques RATIONALE This procedure has been revised to include a new fixed-run test option, provisions for four-wheel drive dynamometer and 20F testing, and updates to definitions and nomenclature aimed at harmonizing these quantit
6、ies across related SAE documents. FOREWORD Electric chassis roll dynamometers provide the means for rapid, accurate, automatic adjustment of dynamometer loading to simulate vehicle road load over the entire speed range through which the vehicle is tested. Precise calibration of chassis roll torque m
7、easurement and speed instrumentation, accurate measurement of base inertia, and controls employing valid algorithms have resulted in accurate dynamometer load coefficient measurements using coastdown techniques without requiring onerous computation and data manipulation by users. Variability of each
8、 dynamometer and between dynamometers is low, permitting load coefficients obtained on one dynamometer to be used on other similar dynamometers. To achieve this interchangeability of loading coefficients, operational factors are specified with the objective of keeping test variability at the low lev
9、els of the dynamometer. This procedure was originally developed in conjunction with the introduction of the 1.219 m (48 in) diameter single-roll electric dynamometer for vehicle emissions and fuel economy testing, however, the methodology is generic to any dynamometer capable of carrying out the roa
10、d load derivation described, regardless of roll size, geometry, or roll surface roughness and is intended to provide a standard of best practice for all vehicle testing requiring accurate road load simulation. SAE INTERNATIONAL J2264 Revised JAN2014 Page 2 of 22 TABLE OF CONTENTS 1. SCOPE 2 1.1 Purp
11、ose . 2 2. REFERENCES 3 2.1 Applicable Documents 3 2.2 Related Publications . 3 3. DEFINITIONS . 4 4. EQUIPMENT . 8 4.1 Dynamometer 8 4.2 Restraint System . 9 4.3 Air Circulation/Cooling . 9 5. COASTDOWN COMPUTATIONS 9 5.1 Integration for Analytically-Obtained Values of t . 10 5.2 Example Calculatio
12、n Sequence 10 6. ROAD LOAD DERIVATION PROCEDURE 13 6.1 Summary . 13 6.2 Recommended Pre-Test Calibration Check . 13 6.3 Vehicle Preparation . 13 6.4 Dynamometer Set-Up . 14 6.5 Vehicle Installation on Dynamometer . 14 6.6 Vehicle Preconditioning. 15 6.7 Road Load Derivation Runs 15 6.8 Iterative Pro
13、cedure 15 6.9 Fixed-Run Procedure 16 6.10 Dynamometer Calibration Verification Coastdown . 17 6.11 Special provisions for Testing at 20F (-7c) . 17 6.12 Road Load Derivation Report . 17 7. NOTES 18 7.1 Conversion Factors . 18 7.2 Marginal Indicia . 19 APPENDIX A SAMPLE REPORTS . 20 FIGURE 1 FLOW CHA
14、RT OF COASTDOWN CALCULATION AND ERROR CORRECTION SEQUENCE 12 FIGURE A1 ROAD LOAD DERIVATION DISPLAY 21 FIGURE A2 TYPICAL MEASURED-TARGET COASTDOWN REPORT . 22 1. SCOPE This procedure covers vehicle operation and electric dynamometer load coefficient adjustment to simulate track road load within dyna
15、mometer inertia and road load simulation capabilities. 1.1 Purpose To provide a uniform procedure for adjusting an electric chassis roll dynamometer to provide accurate simulation of the resistance which must be overcome by the vehicle powertrain to maintain steady speed on a flat road, as determine
16、d by track coastdown tests on that vehicle. SAE INTERNATIONAL J2264 Revised JAN2014 Page 3 of 22 2. REFERENCES 2.1 Applicable Documents The following publications form a part of this specification to the extent specified herein. Unless otherwise indicated, the latest issue of SAE publications shall
17、apply. 2.1.1 HWFET Publication Available from the Superintendent of Documents, U.S. Government Printing Office, Mail Stop: SSOP, Washington, DC 20402-9320. HWFET, Highway Fuel Economy Test, 40 CFR Part 600, Subpart B and Appendix I 2.1.2 Other Publications Dynamometer Performance Evaluation and Qual
18、ity Assurance Procedures (AMA) for a 48 inch Single Roll, Electric Light Duty Chassis Dynamometer 2.2 Related Publications The following publications are provided for information purposes only and are not a required part of this SAE Technical Report. 2.2.1 SAE Publications Available from SAE Interna
19、tional, 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 J1263 Road Load Measurement and Dynamometer Simulation Using Coastdown Techniques SAE Paper 780257 DeRaad, L., “The Influence of Road Surface Texture o
20、n Tire Rolling Resistance,“ SAE Technical Paper 780257, 1978, doi:10.4271/780257. SAE Paper 810166 Oswald, A. and Browne, L., “The Airflow Field Around An Operating Tire and Its Effect on Tire Power Loss,“ SAE Technical Paper 810166, 1981, doi:10.4271/810166. SAE Paper 900760 Metz, L., Akouris, C.,
21、Agney, C., and Clark, M., “Moments of Inertia of Mounted and Unmounted Passenger Car and Motorcycle Tires,“ SAE Technical Paper 900760, 1990, doi:10.4271/900760. SAE Paper 930391 DAngelo, S., Mears, W., and Brownell, C., “Large-Roll Chassis Dynamometer with AC Flux-Vector PEU and Friction-Compensate
22、d Bearings,“ SAE Technical Paper 930391, 1993, doi:10.4271/930391. SAE Paper 930392 Mears, W., DAngelo, S., and Paulsell, C., “Performance Tests of a Large-Roll Chassis Dynamometer with AC Flux-Vector PEU and Friction-Compensated Bearings,“ SAE Technical Paper 930392, 1993, doi:10.4271/930392. SAE P
23、aper 940486 %URZQHOO a shorter soak time up to a minimum of 4 h may be used if consistent with good engineering judgment. b. If actual 20F target coefficients are not available, multiply each term (i.e., F0, F1, F2) of the 68 - 86F Target coefficients by 1.1 and use these as the 20F Target coefficie
24、nts. c. 2SWLRQDOOWZRFRQVHFXWLYHFFOHV WKHILUVWVHFRQGVRIWKH 86FFOH PDEHXVHGWRprecondition the vehicle in-lieu of the two consecutive HWFET cycles specified in Section 6.6. 2) Set coefficients (Dx) derived at 68-86F may be used for testing at 20F (-7C), if consistent with good engineering judegment. 6.
25、12 Road Load Derivation Report Sample reports of road load derivation test results are included in Appendix A. Other formats which include the required information may be used. SAE INTERNATIONAL J2264 Revised JAN2014 Page 18 of 22 7. NOTES 7.1 Conversion Factors 7.1.1 Distance 1 m = 39.3701 in = 3.2
26、808 ft 1 km = 0.62137 mi = 3280.8 ft 1 inch = 25.40 mm = 2.540 cm = 0.0254 m = 1/12 ft 1 mile = 1609.3 m = 1.6093 km = 5280 ft 7.1.2 Speed 1 km/h = 0.62137 mi/h = 0.27778 m/s = 0.91134 ft/s 1 mi/h = 1.6093 km/h = 0.44704 m/s = 1.4667 ft/s 7.1.3 Acceleration 1 (km/h)/s = 0.62137 mi/h/s = 0.27778 m/s2
27、= 0.91134 ft/s21 mi/h/s = 1.6093 (km/h)/s = 0.44704 m/s2= 1.4667 ft/s27.1.4 Mass 1 lb = 0.4536 kg 1 kg = 2.2046 lb 7.1.5 Force 1 N = 0.224809 lb = 0.029974 HP at 50 mi/h 1 lb = 4.4482 N = 0.13333 HP at 50 mi/h 7.1.6 Torque 1 Nm = 0.73756 lbft = 8.8507 lbin 1 lbft = 1.3558 Nm = 12 lbin 7.1.7 Pressure
28、 1 kPa = 0.145037 psi = 0.3196 in Hg = 0.01 bar 1 lb/in2= 6.89476 kPa = 2.2036 in Hg = 0.06895 bar 7.1.8 Energy 1 Nm = 0.73756 ftlb = 1 J = 1 Ws 1 ftlb = 1.3358 NM = 1.3558 J 7.1.9 Power 1 kW = 1.34102 hp = 3600 Nkm/h 1 hp = 2684 Nkm/h = 0.7457 kW = 375 lbmi/h = 550 lbft/s 7.1.10 Standard Gravitatio
29、nal Acceleration 1 g = 35.303 (km/h)/s = 9.80665 m/s2= 21.937 mi/h/s = 32.174 ft/s2SAE INTERNATIONAL J2264 Revised JAN2014 Page 19 of 22 7.1.11 Force Coefficients (Cx) a. C0, 1N = 0.22481 lb 1lb = 4.4482 N b. C11 N/(km/h) = 0.3618 lb/mi/h = 3.6 N/(m/s) 1 lb/mi/h = 2.764 N/(km/h) = 9.9503 N/(m/s) c.
30、C21 N/(km/h)2= 0.5823 lb/mi/h2= 12.957 N/(m/s)21 lb/mi/h2= 1.7176 N/(km/h)2= 22.255 N/(m/s)27.2 Marginal Indicia A change bar (l) located in the left margin is for the convenience of the user in locating areas where technical revisions, not editorial changes, have been made to the previous issue of
31、this document. An (R) symbol to the left of the document title indicates a complete revision of the document, including technical revisions. Change bars and (R) are not used in original publications, nor in documents that contain editorial changes only. PREPARED BY THE SAE J2264 REVISION TASK FORCE
32、OF THE SAE LIGHT DUTY VEHICLE PERFORMANCE AND ECONOMY MEASUREMENTS STANDARDS COMMITTEE SAE INTERNATIONAL J2264 Revised JAN2014 Page 20 of 22 APPENDIX A - SAMPLE REPORTS Appendix A is included as an illustration of the road load derivation computation results. It contains samples of typical vehicle d
33、ata and the details of force curve matching and error correction. Other formats that are demonstrated to produce the same results may also be used. A.1 SCOPE Appendix A covers samples of road load derivation reports generated by the dynamometer. A.2 SAMPLE DYNAMOMETER REPORTS A.2.1 Road Load Derivat
34、ion Display Figure A1 is a printout of the summarized coastdown road load derivation results which is displayed on the dynamometer video monitor. The following describes the information on this report: a. BRAKE, COVER, CRADLE, DIRECTION, LOSS RECORD, COMMENT, etc. - Dynamometer status information. b
35、. DIFF LIMIT - The specified maximum acceptable force difference between the force-versus-speed curves derived from the Target coefficients and from the Measured coefficients, found anywhere within the coastdown speed interval. c. DYNO MEASURED - These are the Measured coefficients computed from the
36、 times measured as the vehicle coasts through each speed interval. d. DYNO SETTING - These are the Set coefficients e. HIGH SPEED - The upper speed of the coastdown speed range. f. HWY INERTIA - ME, the inertia value used in coastdown computations when a vehicle is on the rolls. g. INERTIA - MSet, t
37、he inertia to be simulated by the dynamometer. h. LOW SPEED - The lower speed of the coastown speed range. i. MAXIMUM DIFF - The maximum force difference found between the force versus speed curves derived from the Measured coefficients and from the Target coefficients, over the coastdown speed rang
38、e. j. SET - The final Set coefficients (Dx). k. TARGET - These are the Target coefficients, (Fx). l. VEH - These are the Vehicle coefficients (Lx) representing the vehicle drivetrain friction, determined from the average of the Measured coefficients for the final series of coastdowns which satisfied
39、 the verification runs. SAE INTERNATIONAL J2264 Revised JAN2014 Page 21 of 22 FIGURE A1 - ROAD LOAD DERIVATION DISPLAY A.2.1.1 Typical Measured-Target Coastdown Comparison Figure A2 is a printout of results from one of the coastdowns where the dynamometer is comparing the combined vehicle-dynamomete
40、r loading against the target road load. The following describes the information on this report: a. DIFFERENCE LIMIT - Same as DIFF LIMIT in FIGURE A1. b. FORCE ACTUAL - The road load force, with error correction, at the midpoint of the SPEED RANGE c. FORCE TARGET - The road load force at the midpoin
41、t of the SPEED INTERVAL calculated from TARGET coefficients. d. INERTIA - Same as in Figure A1. e. MAXIMUM DIFFERENCE, etc. - Same as MAXIMUM DIFF in Figure A1. f. MEASURED - Same as DYNO MEASURED in Figure A1. g. POWER ACTUAL - The road load power, with error correction, based on the road load forc
42、e at the midpoint of the SPEED RANGE, resulting from computation based on the TIME ACTUAL. SAE INTERNATIONAL J2264 Revised JAN2014 Page 22 of 22 When power is listed on the dynamometer reports, it is calculated from the corresponding force and mid-range speed: 3600VFkWmid (Eq. A1)where: F = Road loa
43、d force, N Vmid= Mid-speed of coastdown speed interval, km/h h. POWER TARGET - The road load power at the midpoint of the SPEED INTERVAL calculated from TARGET coefficients. i. SET - Same as DYNO SETTING in Figure A1. j. SPEED RANGE - The top and bottom speed of each interval over which the coastdow
44、n is timed. This is the same as “Coastdown speed interval“ under 3.3. k. TARGET - Same as TARGET in Figure A1. l. TIME ACTUAL - The coastdown time actually measured for the SPEED RANGE. m. TIME TARGET - The theoretical coastdown time for the accompanying SPEED RANGE, based on integration of the TARGET coefficients. n. TOTAL HWY INERTIA - Same as HWY INERTIA in Figure A1. o. VEHICLE - Calculated by subtracting the SET coefficients from the MEASURED coefficients. These represent the parasitic friction of the vehicle drivetrain. . FIGURE A2 - TYPICAL MEASURED-TARGET COASTDOWN REPORT
