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.orgJ1492 OCT2008 SURFACEVEHICLERECOMMENDEDPRACTICEIssued 1992-03Revised 2008-10 Superseding J1492 MAY1998 (R) Measurement of Light Vehicle Stationary Exhaust System Sound Level Engine Speed Sweep Method RATIONALEPrior SAE
5、 Standards assumed vehicles could be operated at rated engine speed for the purpose of stationary sound pressure level testing. Technical development of vehicles and engines have changed the operation of many engines and vehicles under stationary conditions. This standard incorporates the changes in
6、 exhaust system configuration and the use of engine management and fuel cut-off systems during stationary conditions. INTRODUCTIONThis sound pressure level measurement procedure has been developed for use in engineering evaluation of the sound pressure level performance of road vehicle in the vicini
7、ty of the exhaust systems. The method is intended to check vehicles in use and also to determine variations in the exhaust sound pressure level, which can result from: the wear, maladjustment, or modification of particular components when the defect does not appear by visual inspection; the partial
8、or complete removal of devices reducing the emission of certain sound pressure levels. It is possible to determine some of these variations by comparing the measurements with reference measurements made under similar conditions using the same method. Other variations can only be detected when the en
9、gine is operated at realistic load. 1. SCOPE This SAE Recommended Practice establishes the test procedure, environment, and instrumentation to be used for measuring the exterior exhaust sound level for passenger cars, multipurpose vehicles, and light trucks under stationary conditions providing a co
10、ntinuous measure of exhaust system sound level over a range of engine speeds. This document applies only to road vehicles equipped with an internal combustion engine. The method is designed to meet the requirements of simplicity as far as they are consistent with reproducibility of results under the
11、 operating conditions of the vehicle. It is within the scope of this document to measure the stationary A-weighted sound pressure level during: measurements at the manufacturing stage measurements at official testing stations measurements at roadside testing Copyright SAE International Provided by I
12、HS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1492 Revised OCT2008 - 2 -It does neither specify a method to check the exhaust sound pressure level when the engine is operated at realistic load nor a method to check the exhaust sound
13、pressure levels against a general noise limit for categories of road vehicles. It provides the means for detecting exhaust system resonances with the potential to affect both exterior and interior sound quality.This document incorporates certain provisions of ISO 5130:2007 for measuring the sound le
14、vel of exhaust systems. (See Appendix A.) 2. REFERENCES 2.1 Applicable Publications The following publications form a part of this specification to the extent specified herein. The latest issue of SAE publications shall apply. 2.1.1 SAE Publications Available from SAE International, 400 Commonwealth
15、 Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org.SAE J184 Qualifying a Sound Data Acquisition System SAE J1349 Engine Power Test CodeSpark Ignition and Compression IgnitionNet Power Rating2.1.2 ANSI Publications Available from AN
16、SI, 25 West 43rd Street, New York, NY 10036-8002, Tel: 212-642-4900, www.ansi.org.ANSI S1.4-1983 Specification for Sound Level Meters ANSI S1.40-1984 Specification for Acoustical Calibrators 2.1.3 ISO Publication Available from ANSI, 25 West 43rd Street, New York, NY 10036-8002, Tel: 212-642-4900, w
17、ww.ansi.org.ISO 5130:2007 AcousticsMeasurement of noise emitted by stationary road vehiclesSurvey method 2.1.4 IEC Publications Available from International Electrotechnical Commission, 3, rue de Verambe, P.O. Box 131, 1211 Geneva 20, Switzerland, Tel: +41-22-919-02-11, www.iec.ch.IEC 60942 Electroa
18、cousticsSound calibrators IEC 61672-1 ElectroacousticsSound level metersPart 1: Specifications 3. DEFINITIONS 3.1 Rated Engine Speed, S Engine speed at which the engine develops its rated maximum net power as defined in SAE J1349. 3.2 Target Engine Speed Engine speed for testing defined in the Recom
19、mended Practice. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1492 Revised OCT2008 - 3 -3.3 Target Engine Speed Range Allowable range of engine speed for valid test based on target engine spe
20、ed and 5% tolerance. 4. INSTRUMENTATION 4.1 The instrumentation necessary to conduct this test shall meet minimum performance requirements as specified herein.4.2 A sound level meter meeting the Type and S1A requirements of ANSI S1.4-1983 or IEC 61672-1. 4.2.1 The sound level meter shall be set for
21、the fast exponential time-averaging characteristic and A-weighting network. 4.3 The calibration of the sound level meter shall be checked and adjusted according to the manufacturers instructions using a calibrator meeting the requirements of ANSI S1.40-1984 or IEC 60942 at the start of measurements
22、and rechecked and recorded at the end of them. (See 8.2.) If the calibration readings of the sound level meter change by more than 0.5 dB during a series of measurements, the test shall be considered invalid. 4.4 A microphone windscreen may be used, provided that it does not affect the microphone re
23、sponse more than 1 dB for frequencies from 20 to 4000 Hz and 1.5 dB from 4000 to 10 000 Hz. 4.5 Engine speed shall be measured with an instrument having an accuracy of 2% or better at the speeds required for the measurements being performed. 5. TEST ENVIRONMENT 5.1 A suitable test site shall be out-
24、of-doors and consist of a level concrete, asphalt, or similar hard material flat surface,free from snow, grass, loose soil, ashes, or other sound absorbing material. It shall be in an open space free from large reflecting surfaces, such as parked vehicles, buildings, billboards, trees, shrubbery, pa
25、rallel walls, people, etc. within a 3 m radius from the microphone location and any point on the vehicle. As an alternative to outside testing, a large hemi-anechoic chamber may be used. The hemi-anechoic chamber shall fulfil the acoustical requirements given above. These requirements shall be met i
26、f the testing facility meets the 3 m distance criteria above and has a cut-off frequency below the lower of: One-third-octave band below the lowest fundamental frequency of the engine during test conditions; 100 Hz. NOTE: Indoor testing facilities noise performance is specified in terms of the cut-o
27、ff frequency (Hz). This is the frequency above which the room can be assumed to act as a semi-anechoic space. 5.2 Background Noise The ambient sound level (including wind effects) from sources other than the vehicle being tested shall be at least 10 dB below that produced by the test vehicle. 5.3 Me
28、teorological Conditions The tests shall not be carried out if the wind speed, including gusts, exceeds 5 m/s, during the sound measurement interval.Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE
29、 J1492 Revised OCT2008 - 4 -6. MICROPHONE ORIENTATION The microphone shall be located at a distance of 0.5 m 0.01 m from the reference point of the exhaust pipe defined in Figure 1 and at an angle of 45 (5) to the vertical plane containing the flow axis of the pipe termination. The microphone shall
30、be at the height of the reference point, but not less than 0.2 m from the ground surface. The reference axis of the microphone shall lie in a plane parallel to the ground surface and shall be directed towards the reference point on the exhaust outlet. If two microphone positions are possible, the lo
31、cation farthest laterally from the vehicle longitudinal centerline shall be used.If the flow axis of the exhaust outlet pipe is at 90 to the vehicle longitudinal centerline, the microphone shall be located atthe point, which is furthest from the engine. If a vehicle has two or more exhaust outlets s
32、paced less than 0.3 m apart and connected to a single silencer, only one measurement shall be made. The microphone shall be located relative to the outlet farthest from the vehicle longitudinal centerline, or when such outlet does not exist, to the outlet, which is highest above the ground. For vehi
33、cles having an exhaust provided with outlets spaced more than 0.3 m apart, one measurement is made for each outlet as if it were the only outlet and the highest sound pressure level shall be noted. For vehicles with a vertical exhaust (e.g. commercial vehicles) the microphone shall be placed at the
34、height of the exhaust outlet. Its axis shall be vertical and oriented upwards. It shall be placed at a distance of 0.5 m 0.01 m from the exhaust pipe reference point as defined in Figure 1, but never less than 0.2 m from the side of the vehicle nearest to the exhaust. For vehicles, where the referen
35、ce point of the exhaust pipe is not accessible, or located under the vehicle body, as shown in Figures 2b and 2c, because of the presence of obstacles which form part of the vehicle (e.g. spare wheel, fuel tank, battery compartment), the microphone shall be located at least 0.2 m from the nearest ob
36、stacle, including the vehicle body, and its axis of maximum sensitivity shall face the exhaust outlet from the position least concealed by the above mentioned obstacles.When several positions are possible, as shown in Figure 2c, the microphone position giving the lowest value of d1or d2shall be used
37、. Figures 2a - d show examples of the position of the microphone, depending on the location of the exhaust pipe. NOTE: For the purpose of roadside checking, the reference point may be moved to the outer surface of the vehicle body. 7. PREPARATION OF THE VEHICLE The vehicle transmission shall be in n
38、eutral position and the clutch engaged, or in parking position for automatic transmission, and the parking brake applied for safety. The vehicle air conditioner, if equipped, shall be turned off. If the vehicle is fitted with fan(s) having an automatic actuating mechanism, this system shall not be i
39、nterfered with during the sound pressure level measurements. The engine hood or compartment cover shall be closed.Before each series of measurements, the engine shall be brought to its normal operating temperature, as specified by the manufacturer.Copyright SAE International Provided by IHS under li
40、cense with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1492 Revised OCT2008 - 5 -T = Top view S = Side view A = Mitered pipe B = Bent down pipe C = Straight pipe D = Vertical pipe 1 = Reference point 2 = Road surface FIGURE 1 - OUTLET PIPE DETAILS Copyr
41、ight SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1492 Revised OCT2008 - 6 -FIGURE 2A - EXAMPLES OF MICROPHONE POSITIONS FOR VARIOUS EXHAUST LOCATIONS:REAR ACCESSABLE EXHAUST OUTLET Copyright SAE Inter
42、national Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1492 Revised OCT2008 - 7 -FIGURE 2B - EXAMPLES OF MICROPHONE POSITIONS FOR VARIOUS EXHAUST LOCATIONS:ANGLED SIDE OUTLET AND UNDERBODY ANGLED OUTLET FIGURE 2C - EXAMP
43、LES OF MICROPHONE POSITIONS FOR VARIOUS EXHAUST LOCATIONS:UNDERBODY REAR OUTLETCopyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1492 Revised OCT2008 - 8 -FIGURE 2D - EXAMPLES OF MICROPHONE POSITI
44、ONS FOR VARIOUS EXHAUST LOCATIONS:VERTICAL OUTLET 7.1 Test Operation 7.1.1 General The sound level meter shall be set for the fast exponential time-averaging characteristic. 7.1.2 Target Engine Speed The target engine speed shall be: 75% of the rated engine speed S for vehicles with S 5000 min-1; 37
45、50 min-1for vehicles with a rated engine speed 5000 S 7500 min-1; 50% of the rated engine speed S for vehicles with S 7500 min-1;with a tolerance of 5%. If the vehicle cannot reach the target engine speed as specified above, the target engine speed shall be 5% below the maximum possible engine speed
46、 for the stationary test. 7.1.3 Engine Operation Conditions The engine speed shall be gradually increased from idle to the target engine speed, not exceeding the tolerance band as given in 6.4.2 and or 6.4.3 and held constant for at least 1 second. Then the throttle control shall be rapidly released
47、 and the engine speed shall be returned to idle. The sound pressure level shall be measured during this entire cycle. The maximum sound level meter reading shall be taken as the test value. The measurement shall be regarded as valid if the test engine speed is held at the target engine speed range f
48、or at least 1 second. NOTE: The change from idle up to target engine speed should occur over a 10 to 15 second interval. Some engines exhibit sensitivity to the rate of increase. The longer time interval tends to reduce run-to-run variability. 7.1.4 Vehicles equipped with a multi-mode exhaust system and a manual exhaust mode control switch shall be tested according to 6.5.2 with the mode switch in all positions. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo
