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
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4、 Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org J1491 REI. JUL2006 SURFACE VEHICLE RECOMMENDED PRACTICE Issued 1985-06 Reissued 2006-07 Superseding J1491 OCT2002 (R) Vehicle Acceleration Measurement RATIONALE SAE J1491 Acceleration and Launch Performance is being
5、updated to: reflect current practice, add standard test conditions, and clarify measurement parameters. 1. SCOPE To define a test procedure that will provide a repeatable measure of a vehicles launch response and maximum accelleration performance. 1.1 Purpose This SAE Recommended Practice provides a
6、 standardized means of measuring launch response and acceleration performance of passenger cars and light-duty trucks. 2. REFERENCES There are no referenced publications specified herein. 3. DEFINITIONS 3.1 Time Zero The time used in the calculation for Launch Response Time and Acceleration Response
7、 Time. It is derived as specified in Section 9. 3.2 Launch Response Time Vehicle response in seconds from driver control input measured by a) initial throttle pedal movement (automatic transmission) or b) clutch movement (manual transmission) to Initial Vehicle Movement. See 3.3. 3.3 Initial Vehicle
8、 Movement (IVM) Movement of vehicle a distance of 0.3048 m (one foot) from rest position. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1491 Reissued JUL2006 - 2 - 3.4 Acceleration Response Ti
9、me Vehicle response in seconds from IVM to test end speed or distance. The Acceleration Response Time for distance is usually calculated at one quarter mile (0.402km). 3.5 Unloaded Vehicle Weight The weight of the vehicle as built with production parts with maximum capacity of all fluids necessary f
10、or operation of the vehicle. 3.6 Miles per Hour Miles per hour is a unit of speed, expressing the number of international miles covered per hour. The common abbreviation in everyday use is mph, although mi/h, using the SI method of expressing derived units, is sometimes used, especially in the Unite
11、d States. The preferred SI unit for velocity is m/s, although km/h is often used as a replacement for mph. 4. INSTRUMENTATION (All instrumentation must be calibrated.) 4.1 Speed Instrumentation to measure vehicle speed as a function of elapsed time meeting the following specifications: a. Time 1. Ac
12、curacy 0.1 s 2. Resolution 0.1 s b. Vehicle Speed 1. Accuracy 0.8 km/h (0.50 mph) 2. Resolution 0.4 km/h (0.25 mph) c. Engine Speed (tachometer) 1. Accuracy 50 rpm 2. Resolution 25 rpm 4.2 Distance (One Foot) Optional Equipment to measure Initial Vehicle Movement. 1. Accuracy 5 mm 2. Resolution 12.5
13、 mm NOTE: This equipment is optional since the one foot distance used in calculations may be made by integration of speed. 4.3 Temperature The ambient temperature measurement devices must have a resolution of 1 C (2 F) and an accuracy of 1 C (2 F). The sensing elements must be shielded from radiant
14、heat sources. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1491 Reissued JUL2006 - 3 - 4.4 Atmospheric Pressure A barometer with an accuracy of 0.7 kPa (0.2 in Hg). 4.5 Wind Wind speed and di
15、rection during the test should be continuously monitored. Wind measurements should permit the determination of average longitudinal and crosswind components to within 2 km/h (1 mph). 4.6 Vehicle Weight Vehicle weight should be measured to an accuracy of 5 kg (10 lb) per axle. 4.7 Tire Pressure Shoul
16、d be measured to an accuracy of 7 kPa (1 psi). 4.8 Distance (optional) A distance indicating device is required for the 402 m (1/4 mile) test so that driver knows when to end test. This device must be capable of indicating distance to within 1 ft and must be capable of accuracy within 1 m in 1 km (5
17、 ft in 1 mile). Fixed markers at the side of the test road can also be used. NOTE: The 0.3048 m (one foot) test point will be measured using the speed and time during the data calculations. 4.9 Throttle Position Monitor (optional) A readout to monitor/regulate throttle position. This can be used to
18、monitor/regulate wheel spin on some vehicles. 4.10 Accelerometer (optional) An accelerometer may be used to help in the analysis of data by providing information on shift points. An accelerometer with 2.0 g capability, 1% accuracy and .005 g resolution is suggested. 5. TEST MATERIAL 5.1 Test Vehicle
19、 The test vehicle will normally be representative of a standard production built vehicle; any nonstandard equipment must be noted (i.e., roof racks, optional mirrors, fog lamps, spoilers, optional axle ratio, etc.). Record any equipment that is removed for test. The vehicle mass shall be set for the
20、 intended test purpose and recorded. Consideration should be made to test automatic transmission shift modes like “sport” or “power.” 5.2 Test Fuel Commercially available fuel as recommended by the manufacturer will normally be used for test purposes. If the information is available or if a special
21、test fuel is used, the fuel specifications should be recorded, such as: fuel generic type, gasoline octane rating or diesel cetane rating, brand name, specific gravity, Reid vapor pressure. 5.3 Lubricants Lubricants used shall conform to the manufacturers recommendation for the predominant weather c
22、ondition in which the vehicle is being tested. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1491 Reissued JUL2006 - 4 - 6. TEST CONDITIONS 6.1 Ambient Conditions Tests should be run as close
23、as possible to the standard conditions: TABLE 1 STANDARD AMBIENT CONDITIONS Standard Condition Correction preferred but not required if within this range Test Range Ambient temperature 20 C (68 F)(1)15 25 C (59 77 F) 1.0 and 32 C (30 and 90 F) Barometric Pressure (absolute) 98.21 kPa (29.0 in Hg)(1)
24、98-100 kPa 90-102 kPa Relative Humidity 50% 40 60% 95% 1. Standard condition temperature and pressure are based on SAE J2263, “Roadload Measurement Using Onboard Anemometry and Coastdown Techniques.” 6.2 Adverse Weather Conditions The tests may not be run during foggy, rainy, or snowy conditions. 6.
25、3 Wind Velocity The tests may not be conducted when wind speeds average more than 24 km/h (15 mph) (or when peak wind speeds are more than 32 km/h (20 mph). 6.4 Road Conditions The roads must be dry, clean, smooth, and must not exceed 0.5% grade. In addition, the grade should be constant and the roa
26、d should be straight. The road surface should be concrete or rolled asphalt (or equivalent) and in good condition; testing should not be conducted on slippery roads. 6.5 Speed Limitation These tests should be run on a controlled track or proving grounds. If run on public roads or highways, speed sho
27、uld not exceed posted speed limit, and vehicle should not interfere with traffic flow or otherwise operate in a manner that would be hazardous. 7. VEHICLE PREPARATION 7.1 Break-In The vehicle should have at least 1609 km (1000 miles) of operation or mileage to assure vehicle performance is stabilize
28、d as determined by manufacturer. Tires must have at least 75% of the tread remaining and tread must be in good condition. All tires must have at least 161 km (100 miles) of run in before test. 7.2 Vehicle Check List The vehicle must be inspected and adjusted where necessary to meet manufacturers spe
29、cifications, particularly if vehicle is exhibiting abnormal performance characteristics during acceleration. Tune and time engine, and make all other adjustments, such as front end alignment, and functional checks in accordance with manufacturers published procedures. Operate, observe, and reset, if
30、 necessary, the throttle system linkage to ensure that wide open throttle occurs. If the vehicle is equipped with automatic transmission, ensure that automatic transmission shift points are within manufacturers published specifications. Ensure that brake drag is not excessive. Copyright SAE Internat
31、ional Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1491 Reissued JUL2006 - 5 - 7.3 Instrumentation The speed-time measurement device and other necessary test equipment must be installed so that they do not hinder vehicl
32、e operation or alter the operating characteristics of the vehicle. 7.4 Test Weight The vehicle weight shall be set for the intended test purpose and recorded. 7.5 Tire Pressure The cold tire pressure should be the standard recommended by the manufacturer for the vehicle test weight and installed tir
33、es. 7.6 Vehicle Warm-up The vehicle must be driven a minimum of 32 km (20 miles) at an average speed of 88 km/h (55 mph 5 mph) immediately prior to the test. Alternative schedules that provide equivalent vehicle warm-up can be substituted. There should not be more than a 5 min time lapse between the
34、 warm-up and the start of test. 8. TEST PROCEDURE 8.1 Test Schedules Summary Perform wide open throttle (WOT) accelerations from a standing start and record the following: Launch Response Time (Control Input to IVM) Acceleration Response Time (IVM to test end speed) Also perform the following test a
35、t wide-open-throttle: 64 to 97 km/h (40 to 60 mph) Elapsed Time 8.2 Automatic Transmission Operating Procedure From a standing start with engine at idle (braked, if necessary), with the shift selector in the “drive” position for normal operation, accelerate with wide-open-throttle. The vehicle shoul
36、d be operated to achieve maximum performance with minimum wheel spin. Begin recording data the instant the drivers foot moves the accelerator pedal. 8.3 Manual Transmission Operating Procedure From a standing start, the vehicle should be operated to achieve maximum performance with minimum wheel spi
37、n. Clutch operation, as well as shift point selection, should be optimized for performance without exceeding the maximum specified engine rpm. Begin recording data at the instant of clutch pedal movement. 8.4 Test Procedure 40 to 60 Starting from a stabilized 64 km/h (40 mph), accelerate with wide-o
38、pen throttle to 97 km/h (60 mph). Manual transmissions should be run both in top gear and top gear less one, with 4- or 5-speed transmissions. Test in 4th and 5th gear with a 6-speed manual transmission. Three-speed manual transmission should be run in top gear only. Manual transmissions should not
39、be downshifted during this test. Begin recording data on throttle or clutch pedal movement per the manual or automatic procedure in 8.3 or 8.4 as applicable. Automatic transmissions will be allowed to downshift as determined by the vehicle transmission controls. Copyright SAE International Provided
40、by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1491 Reissued JUL2006 - 6 - 8.5 Number of Tests and Delay 8.5.1 Run a minimum of three pairs of tests, with each pair conducted in opposing directions. When difficulty is experienced
41、in one run, the pair is excluded. 8.5.2 A delay period of 30 seconds (default) or as requested by engineer is required between runs to maintain “closed-loop” mode. The delay avoids built-in engine control calibration overrides or changes which may occur under repeated back-to-back runs. The delay in
42、terval must be done with the vehicle moving to allow powertrain cool down. 8.6 Operation of Accessories The headlamps are to be off. If the vehicle is equipped with pop-up lamps, the lamp pods should be in the down position. The lights should be on if required for safe vehicle operation, and so note
43、d in test results. The heater blower motor shall be used in the “low“ position only. Vehicles equipped with air conditioning should have the compressor clutch wire disconnected before the start of test. Radio operation is optional. All other electrical accessories must be in the off position. Window
44、s should remain closed during test runs. Traction control system shall be in the “state providing maximum acceleration” determined by the requesting engineer. 9. DATA REDUCTION 9.1 Data Calculation 9.1.1 Time Zero. Launch and Acceleration Response Only Time Zero is the time at which the pedal has go
45、ne through 10% of its travel. See Figure 1. FIGURE 1 GRAPHICAL DEFINITIONS 9.1.2 One Foot Calculate the one foot distance by integrating the speed/time data to obtain a distance plot. See Figure 1. It may also be measured directly using optional instrumentation. Copyright SAE International Provided
46、by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1491 Reissued JUL2006 - 7 - 9.1.3 Launch Response Time Calculate Launch Response Time from Time Zero (% Pedal) to the end of Initial Vehicle Movement (One foot distance). 9.1.4 Accele
47、ration Response Time Calculate Acceleration Response Time from the end of Initial Vehicle Movement (One foot distance) to specific test end speed or distance. These test end speeds are typically at 30 mph (48.3 kph) and 60 mph (96.6 kph). The Acceleration Response Time for distance is usually calcul
48、ated at one quarter mile (0.402 km). 9.1.5 Interval 64 to 97 km/h (40 to 60 mph) Elapsed Time Calculate Elasped Time from initial throttle or clutch pedal movement (use calculated % pedal similar to Launch Response Time (Figure 1) to end speed (97 km/h (60 mph). 9.2 Data Presentation 9.2.1 Vehicle and Test description Record descriptions of the following systems: Vehicle (including manufacturer, model, year, odometer, VIN, weight, optional equipment) engine, transmission, tire and tire p
