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 there
2、from, 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 2006 SAE International All rights reserved. No part of this publication m
3、ay 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.org J1269 REV. SEP2006 SURFACE VEHICLE RECOMMENDED PRACTICE Issued 1979-11 Revised 2006-09 Superseding J1269 SEP2000 Rolling Resistance Measurement Procedure for Passenger Car, Light Truck, and Highway Truck and Bus Tire
5、s RATIONALE This procedure is intended to provide a standard method for gathering data on a uniform basis, to be used for various purposes (for example, tire comparisons, determination of load or pressure effects, correlation with test results from fuel consumption tests, etc.). This document has be
6、en modified in order to provide a relevant single point test condition (Standard Reference Condition SRC) appropriate for high volume rolling resistance testing such as for regulatory or comparative purposes. FOREWORD This SAE Recommended Practice provides methods for determining rolling resistance
7、of passenger car, light truck, and highway truck and bus tires under controlled conditions. The procedure is intended to provide a way of gathering data on a uniform basis, to be used for various purposes (for example, tire comparisons, determination of load or pressure effects, correlation with tes
8、t results from fuel consumption tests, etc.). A companion document, SAE Information Report J1270, Measurement of Passenger Car, Light Truck, and Highway Truck and Bus Tire Rolling Resistance, enlarges on this subject and gives background information. The format of both documents is the same, with co
9、rresponding topics presented under the same headings. 1. SCOPE This SAE Recommended Practice applies to the laboratory measurement of rolling resistance of pneumatic passenger car, light truck, and highway truck and bus tires. The procedure applies only to the steady-state operation of free-rolling
10、tires at zero slip and inclination angles; it includes the following three basic methods: 1.1 Force Method Measures the reaction force at the tire spindle and converts it to rolling resistance. 1.2 Torque Method Measures the torque input to the test machine and converts it to rolling resistance. 1.3
11、 Power Method Measures the power input to the test machine and converts it to rolling resistance. SAE J1269 Revised SEP2006 - 2 - 2. REFERENCES 2.1 Applicable Publications The following publications form a part of the specification to the extent specified herein. Unless otherwise indicated, the late
12、st revision of SAE publications shall apply. 2.1.1 SAE Publication Available from SAE, 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 J1270 Measurement of Passenger Car, Light Truck, and Highway Truck, and
13、Highway Truck and Bus Tire Rolling Resistance 2.1.2 Tire and Rim Association Available from Tire and Rim Association, 175 Montrose West Avenue, Suite 150, Copley, OH 44321. Tire and Rim Association Yearbook 3. DEFINITIONS The following definitions apply wherever the terms and expression are used in
14、this document and in SAE J1270. 3.1 Rolling Resistance Rolling resistance of the free-rolling tire is the scalar sum of all contact forces tangent to the test surface and parallel to the wheel plane of the tire. 3.2 Rolling Resistance Coefficient Rolling resistance coefficient is the ratio of the ro
15、lling resistance to the load on the tire. 3.3 Loaded Radius Loaded radius is the perpendicular distance from the axis of rotation of the loaded tire to the surface on which it is rolling. 3.4 Maximum Load Maximum load is molded on the tire sidewall and listed as the load limit in the tire load table
16、s of the current Tire 2 h or more for passenger and light truck tire, 6 h or more for highway truck and bus tires. If the standard test is used (5.1), the tire must be inflated on the test rim at least 1 h before testing. 6.3 Warm-Up The tire must be run on the test surface under each set of conditi
17、ons long enough to achieve a steady-state value of rolling resistance. SAE J1269 Revised SEP2006 - 8 - The following warm-up time is required for the first condition: 30 min for passenger car tires 60 min for light truck tires 90 min for highway truck and bus tires For each of the remaining conditio
18、ns, the following warm-up time is required: 10 min for passenger car tires 15 min for light truck tires 30 min for highway truck and bus tires The achievement of steady-state conditions can be verified by monitoring the rolling resistance. 6.4 Measurement and Recording 6.4.1 Identification The follo
19、wing information for the identification of each test should be recorded, if applicable. 6.4.1.1 Tire Identification a. Manufacturer b. Brand name c. Tire size and load range (if applicable) d. Tire maximum load (see 3.4) e. Tire base inflation pressure (see 3.5) f. Serial number g. Break-in informat
20、ion h. Use - history of tire i. Other pertinent information 6.4.1.2 Test Machine Identification a. Test wheel diameter b. Test wheel surface texture and general condition c. Tire mounting configuration d. Method of parasitic loss determination e. Other pertinent information SAE J1269 Revised SEP2006
21、 - 9 - 6.4.1.3 Test Conditions a. Date and time b. Rim width and contour c. Rotational direction (clockwise or counter-clockwise) determined for the tire side with serial number. 6.4.2 Test Variables The following test data must be recorded immediately after the warm-up period for each load-pressure
22、 combination: a. Warm-up time period b. Speed c. Load d. Inflation pressure e. Spindle force, input torque, or input electrical power, as appropriate f. Loaded radius (required for force method) g. Ambient temperature (see 5.5) 6.5 Measurement of Parasitic Losses Parasitic losses can be determined b
23、y different techniques. Two commonly used methods for estimating parasitic losses are: 6.5.1 Skim Reading Load on the tire must be reduced to a value just sufficient to maintain tire rotation at test speed without slippage. The following skim loads are recommended: 100 N (20 lbf) for passenger car t
24、ires 150 N (35 lbf) for light truck tires 220 N (50 lbf) for highway truck and bus tires 6.5.2 Machine Offset Reading The tire and wheel assembly is removed from the test surface. At test speed, input torque or input electrical power is read (whichever applies). Note that this method does not apply
25、if the force method is used. Note also that the parasitic losses of the rotating tire and wheel assembly are not measured and must be determined separately. 7. DATA REDUCTION 7.1 Net Readings via Subtraction of Parasitic Readings Parasitic losses must be subtracted from the gross readings to yield n
26、et spindle force, net torque, or net electrical power (whichever applies). Two commonly used techniques for estimating the effect of parasitic losses are: 7.1.1 Skim Reading (for Force, Torque, and Power Method) Subtract the skim reading from the reading for each test condition. SAE J1269 Revised SE
27、P2006 - 10 - 7.1.2 Machine Offset Reading (For Torque and Power Method) Subtract the machine offset reading and, in addition, the tire spindle bearing loss from the reading for each test condition. 7.2 Compensation for Load-Spindle Force Interaction and Load Misalignment Compensation for both load-s
28、pindle force interaction (“crosstalk”) and load misalignment must be determined for each of the test points (5.1 or 5.2). This is accomplished either by recording the spindle force for both forward and reverse tire rotation, or by dynamic machine calibration. If spindle force is recorded for forward
29、 and reverse direction (at each test condition), compensation is achieved by subtracting the “reverse” value from the “forward” value and dividing the result by two. If dynamic machine calibration is elected, the compensation terms may be easily incorporated in the data reduction process. 7.3 Rollin
30、g Resistance Calculation Rolling resistance must be calculated by using a formula appropriate to the measuring method. 7.3.1 Force Method ()R/R1FFLXR+= (Eq. 1) where: FR= rolling resistance, N (lbf) FX= magnitude of net tire spindle force, N (lbf) RL= loaded radius, m (in) R = test wheel radius, m (
31、in) 7.3.2 Torque Method R/TFR= (Eq. 2) where: FR= rolling resistance, N (lbf) T = net input torque, Nm (lbfin) R = test wheel radius, m (in) 7.3.3 Power Method v/PcFR= (Eq. 3) where: FR= rolling resistance, N (lbf) c = 3.60 for speed in km/h c = 0.503 for speed in mph P = net power input, W v = test
32、 surface speed, km/h (mph) SAE J1269 Revised SEP2006 - 11 - 7.4 Data Adjustment to Ambient Reference Temperature Individual values of rolling resistance must be adjusted to reference temperature of 24 C (75 F) by use of the relation: ()()lbfN,TTk1FFRARRR+= (Eq. 4) where: FRR= rolling resistance at A
33、mbient Reference Temperature, N (lbf) FR= rolling resistance measured at a test point, N (lbf) TA= average ambient temperature measured at a test point, C (F) TR= Ambient Reference Temperature k = temperature adjustment factor, (C)-1or (F)-1The factor k is determined empirically; current results (Se
34、e Ref. 1 of SAE J1270) indicate an average value of k = 0.0060 (C)-1or 0.0033 (F)-1. 8. DATA ANALYSIS For some purposes, additional conversion and analysis of the data are desirable. The calculations shown as follows are presented for convenience and easy reference. 8.1 Rolling Resistance Coefficien
35、t The rolling resistance coefficient is calculated by dividing the rolling resistance by the load on the tire: ZRRF/FC = (Eq. 5) where: CR= rolling resistance coefficient, dimensionless FR= rolling resistance, N (lbf) FZ= tire load, N (lbf) 8.2 Multiple Linear Regression The test data for a single t
36、ire or the data for a sample of several nominally identical tires may be used for this analysis. The data are fitted by a least-squares regression model as follows: Passenger Car Tires ( )p/2Z10ZRAFAAFF += (Eq. 6) Light Truck Tires 2p/Z4p/Z3p/2Z10RFAFAAFAAF += (Eq. 7) Highway Truck and Bus Tires 2p/
37、Z3p/Z2Z10RFAFAFAAF += (Eq. 8) FR= equilibrium rolling resistance, N (lbf) )lbf(N,loadtireFZ= (Eq. 9) SAE J1269 Revised SEP2006 - 12 - p = equilibrium inflation pressure, kPa (psi) tscoefficien)etc(A,A,A210 (Eq. 10) The resulting regression equation may be used to calculate values for rolling resista
38、nce at loads and pressures other than those tested, but extrapolation far beyond the range of the test matrix, particularly for the region of high load and low pressure, is not advised. 8.3 Flat Surface Approximation Rolling resistance data generated on a test wheel may be converted to a flat surfac
39、e approximation by means of the following expression:2()2/1R/r1FFRWRf+= (Eq. 11) where: FRf= rolling resistance on a flat surface, N (lbf) FRW= rolling resistance on a test wheel, N (lbf) r = nominal tire radius, m (in) R = test wheel radius, m (in) 9. NOTES 9.1 Marginal Indicia The change bar (l) l
40、ocated in the left margin is for the convenience of the user in locating areas where technical revisions have been made to the previous issue of the report. An (R) symbol to the left of the document title indicates a complete revision of the report. PREPARED BY THE SAE HIGHWAY TIRE FORUM COMMITTEE 2This expression for the flat surface approximation is not yet proven for universal application. Its inclusion does not constitute an endorsement of its validity, but merely signifies that it represents current state-of-the-art knowledge. See SAE J1270 for further comments.
