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4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/standards.sae.org/J1270_201710 SURFACE VEHICLE INFORMATION REPORT J1270 OCT2017 Issued 1979-10 Revised 2006-09 Re
5、affirmed 2017-10 Superseding J1270 SEP2006 Measurement of Passenger Car, Light Truck, and Highway Truck and Bus Tire Rolling Resistance RATIONALE J1270 has been reaffirmed to comply with the SAE Five-Year Review policy. FOREWORD This information report is a companion document to SAE Recommended Prac
6、tice, J1269, Rolling Resistance Measurement Procedure for Passenger Car, Light Truck and Highway Truck and Bus Tires. It provides background information and explanations related to the use of the Measurement Procedure and follows the same format as SAE J1269. 1. SCOPE1.1 Basic Methods The force, tor
7、que, and power methods of measurement are all in common use and should yield the same test results. Effects of steering, traction, surface texture, and non-steady-state tire operations are excluded from the recommended practice because they are still in the research stage. 1.1.1 Force Method The chi
8、ef advantage of the force method is that the only parasitic losses in the measurement are tire spindle bearing losses and aerodynamic losses associated with rotation of the tire and its wheel. The main disadvantage of this method is that the spindle force measured can contain a severe error caused b
9、y load misalignment and load-spindle force interaction (“crosstalk”). Elimination or compensation of these effects is necessary. A minor disadvantage is that the loaded radius of the tire must be measured in order to convert spindle force to rolling resistance. 1.1.2 Torque Method The torque method
10、has the advantage that the measurement is direct: rolling resistance is the net torque divided by the test wheel radius. The main disadvantage of the torque method is that parasitic losses contained in the measurement include rotational test wheel losses as well as tire spindle losses. Hence, the pa
11、rasitic losses are larger than those of the force method and can be of the same order of magnitude as the rolling resistance itself. In addition, speed-hunting oscillations in the drive motor can introduce errors. 1.1.3 Power Method The advantage of the power method is that no force or torque transd
12、ucer is necessary; a voltmeter and an ammeter to measure the electrical energy input to the drive system are sufficient. The chief disadvantage of the power method is that electrical losses are included in the measurement in addition to all the other parasitic losses of the system. Thus, the parasit
13、ic losses are even larger than those of the torque method. In some laboratories, special control may be needed to prevent line voltage fluctuations from creating power surges which can distort the readings. 2. REFERENCES 2.1 Applicable Publications The following publications form a part of the speci
14、fication to the extent specified herein. Unless otherwise indicated, the latest 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.
15、 SAE J1269 Rolling Resistance Measurement Procedure for Passenger Car, Light Truck, and Highway Truck and Bus Tires 2.1.2 Other Publications 1. D. J. Schuring and G. L. Hall, “Ambient Temperature Effects on Tire Rolling Loss,” Rubber Chemistry and Technology, Vol. 54, No. 5, pp. 11131123 (1981). 2.
16、R. Masaki, Y. Tanida, C. Ikeya, and I. Harada, “Research on Rolling Resistance of Tires,” J. Mech. Lab., Japan, Vol. 4, No. 1, p. 43 (1958). 3. S. K. Clark, “Rolling Resistance Forces In Pneumatic Tires,” DOT/TSC, Report No. DOT-TSC-76-1 (January 1976). 4. J. R. Luchini, “Test Surface Curvature Redu
17、ction Factor For Truck Tire Rolling Resistance,” SAE Paper No. 821264 (1982). 3. DEFINITIONS 3.1 Rolling Resistance The definition given in the recommended practice applies only to the free-rolling mode. The universal rolling resistance definition from which it is derived is defined as the energy ex
18、pended by the tire per unit distance traveled. 3.2 Rolling Resistance Coefficient No further background information is required in this section. 3.3 Loaded Radius No further background information is required in this section. 3.4 Maximum Load The maximum tire load is expressed in kilograms (kg) or p
19、ounds (lb), which are units of mass. For use in the recommended practice, these units must be converted to units of force, either to the newton (N) or the pound-force (lbf). SAE INTERNATIONAL J1270 OCT2017 Page 2 of 8_ 3.5 Base Inflation Pressure Base inflation pressure is the inflation pressure cor
20、responding to the maximum load listed in the tire load tables of the current TRA Yearbook or in corresponding tables published by similar organizations concerned with standardization. 3.6 Capped Inflation Pressure As the tire with inflation pressure capped is run under load, the rising tire temperat
21、ure will cause the inflation pressure to increase. Thus, capped inflation pressure reflects actual road service conditions. 3.7 Regulated Inflation Pressure Pressure is most commonly regulated by a constant pressure source attached to the tire through a rotating union. 3.8 Ambient Temperature An ove
22、rall ambient room temperature representing air temperatures throughout the test room is difficult to define and measure. Therefore, a location close to the cooler part of the tire/wheel assembly was selected for ambient temperature measurements. 3.9 Ambient Reference Temperature Variations in rollin
23、g resistance occur with changes in ambient temperature. Because precise control of room temperature is difficult, rolling resistance data must be referred to 24 C (75 F) according to paragraph 7.4 of SAE J1269. 4. TEST EQUIPMENT An objective of the recommended practice is to provide a test procedure
24、 that nearly all test organizations can adopt as standard. Since the most common equipment is the laboratory test wheel, it serves as a standard for the procedure. However, most of the provisions of this recommended practice do apply to flat-surface laboratory test apparatus. Note that rolling resis
25、tance results from a laboratory test wheel are usually slightly higher than corresponding results from a flat surface test machine because of the greater tire deflection on the curve test wheel surface (see 8.3). 4.1 Test Surface 4.1.1 Test Wheel Diameter Most standard laboratory test wheels have a
26、diameter of 1.708 m (67.23 in) derived from a circumferential length of 1/300 mile. 4.1.2 Width Most laboratory test wheels have a surface width of at least 0.30 m (12 in). 4.1.3 Texture Rolling resistance is affected by road texture in a manner still under study. The selection of medium-coarseness
27、abrasive-type surface for this test procedure is designed to simulate results on a dry, well-maintained public roadway. Periodic renewal of the surface is necessary because contamination or wear adds variability to the test results. 4.2 Test Rims The test rim selected should represent a rim used as
28、original equipment and conform to specifications of the TRA or similar organizations. Because of the wide variety of rims available for some tire sizes, and because the rim may affect rolling resistance, it is important to report test rim width and contour along with the test results. Since rim runo
29、ut may affect rolling resistance, good quality rims must be used. SAE INTERNATIONAL J1270 OCT2017 Page 3 of 8_ 4.3 Alignment and Control Accuracies The limits given are selected to minimize the error of rolling resistance data and thus to aid accurate comparisons of different rolling resistance faci
30、lities. The limits reflect standard deviations from the true value; they do not cover systematic errors, which must be eliminated by careful calibration and proper data processing. 4.3.1 Force Method Misalignment of the tire load may result in a significant spindle force component that could be misi
31、nterpreted as rolling resistance. To eliminate this effect, very low limits for tire load offsets would be required (on the order of 0.005 degree for angular offset and 0.02 mm for fore-aft offset). To avoid maintaining impractically low load offsets, a correction technique for load misalignment mus
32、t be developed for facilities employing the force method. The load misalignment correction technique is frequently combined with the correction technique for load-spindle force crosstalk (see 7.2). 4.3.2 Torque Method The large polar moment of inertia of the test wheel gives rise to substantial torq
33、ue variations even if speed variations are very small. Since these torque variations can be misread as rolling resistance, they must be filtered out either statistically or electronically. 4.3.3 Power Method If surface speed cannot be controlled to 0.3 km/h (0.2 mph) for passenger car and light truc
34、k tires, or controlled to 0.8 km/h (0.5 mph) for highway truck and bus tires, the input electrical power should be averaged over several speed cycles and the average speed used in the rolling resistance calculation. 4.4 Instrumentation Accuracy The values selected reflect common accuracies of modern
35、 equipment. In laboratories where more accurate instruments are available, better measurement resolution is encouraged. The specific values recommended are adequate for the following: TABLE 1 INSTRUMENTATION ACCURACY Typical Normal Load Typical Rolling Resistance Produced Passenger Car Tire 5 kn (11
36、00 lbf) 35 N ( 8 lbf) Light Truck Tire 10 kn (2200 lbf) 100 N (22 lbf) Highway Truck and Bus Tires 22 kn (5000 lbf) 220 N (50 lbf) 4.4.1 Force Method This method requires measurement of spindle force and loaded radius. The force measurement must be very precise; it requires careful selection or spec
37、ification of current-technology equipment. 4.4.2 Torque Method This method requires precise measurement of input torque. Modern torque cells may require separate over-torque protection to ensure the needed resolution. 4.4.3 Power Method This method requires precise measurement of electrical power an
38、d speed. The speed resolution required for this method is higher than for the other methods because the average speed during the measurement interval is used in the calculation of rolling resistance. SAE INTERNATIONAL J1270 OCT2017 Page 4 of 8_ 5. TEST CONDITIONS 5.1 Load and Inflation PressureStand
39、ard Test The capped inflation pressure test condition (Test Point 1) in combination with the regulated inflation pressure test conditions constitute the basis for predicting rolling resistance over a wide range of operating conditions. 5.2 Load and Inflation PressureAlternate Test The accuracy of th
40、e predicted values at various loads and inflation pressures is not compromised if the first test point is run at regulated inflation pressure, indicated as Test Point 1A. The final capped inflation pressure at temperature equilibrium of Test Point 1 will usually be close to the regulated inflation p
41、ressure at Test Point 1A so that both points will yield very similar rolling resistance values. Regulated pressure is believed to enhance testing efficiency and to improve the predictive accuracy of the regression model (see 8.2). Note, however, that the alternate test does not deliver information a
42、bout the pressure rise that would occur under normal road service conditions. 5.3 Test Sequence Experiments have suggested that steady-state conditions are achieved more quickly for steps of decreasing rolling resistance. Thus, in order to shorten the total test and at the same time ensure steady-st
43、ate values at all test conditions, testing in the order of decreasing values of rolling resistance is recommended. 5.4 Standard Reference Condition (SRC) for PC and LT Tires The SRC is intended to serve as a simple, single-point measurement that can be used for comparison of the coefficient of rolli
44、ng resistance between tires of different sizes, under their typical use conditions, and for high volume rolling resistance evaluations. 5.5 Test Speed A single speed is recommended, because rolling resistance at equilibrium (steady-state) is relatively insensitive to speed over the range from 60 to
45、100 km/h (40 to 60 mph). 5.6 Ambient Temperature The recommended procedure is a compromise of sufficient accuracy for temperature compensations (see 7.4) within the range between 20 C (68 F) and 28 C (82 F). A representative temperature average is required for each test point. The control of ambient
46、 temperature varies between different laboratories, and various methods may be used to obtain an average temperature for each point. A method for obtaining an average would be to measure the ambient temperature at the beginning, middle, and end of a test point and average the three values. Other ave
47、raging techniques may provide similar results. The intent here is to measure an average temperature and not to take an instantaneous temperature reading. An instantaneous reading may not accurately reflect ambient conditions because the ambient temperature may change during a test. 6. TEST PROCEDURE
48、 6.1 Break-In The cool-down period of at least 2 h for passenger car and light truck tires, or at least 6 h for highway truck and bus tires is recommended to assure that the tire has reached a uniform temperature equal to the ambient temperature. If the tire has undergone other tests prior to the rolling resistance test, break-in may not be necessary. SAE INTERNATIONAL J1270 OCT2017 Page 5 of 8_
