1、UDC 534.61 : 621.43: 534.835.46 DEUTSCHE NORM January 1987 Airborne noise emission, enveloping surface method I Internal combustion engines I Measurement of noise emitted by machines I DIN I 45635 Part 11 Geruschmessung an Maschinen; Luftschallemission, Hllflchen-Verfahren; Verbrennungsmotoren In ke
2、eping with current practice in standards published by the International Organization for Standardization (ISO), a comma has been used throughout as the decimal marker. Supersedes September 1974 edition. Contents Page 1 Scope and field of application 1 2 Designation 1 3 Terminology, quantities. . 1 4
3、 Instrumentation . 2 5 Object under test and test conditions . 2 6 Testprocedure 4 1 This standard, together with DIN 45 635 Part 1, April 1984 edition, provides a basis for determining noise emitted by internal combustion engines (direct noise emission and airborne noise emission) by standard meth-
4、 ods so as to obtain reproducible results. The sound power level is used as the principal noise emission parameter. (See Supplement 2 to DIN 45 635 for information regarding noise emission parameters.) This standard applies to internal combustion engines, including engines for - industrial applicati
5、ons (e.g. stationary engines); - prime movers for working equipment and working machines; - water vehicles; - rail vehicles; - road vehicles; - machines. The measurement method specified in this standard only permits determination of the noise of internal combustion engines but not that radiated fro
6、m driven machinery. The result of a measurement made in accordance with this standard can be classified as of grade 2 accuracy or grade 3 accuracy according to which of the requirements regarding the acoustic measurement conditions given in table 1 of DIN 45 635 Part 1 have been complied with. The r
7、esults may only be classified as of grade 2 accuracy, as specified in subclause 5.5 of DIN 45 635 Part 1, if the test environment represents a largely free field over a reflecting plane (required environmental correction, KZA, less than 2 dB) and if the background noise level is low enough (required
8、 background noise correction, engine speed: as defined in DIN 6271 Part 1; octane number: as defined in DIN 51 600; cetane number: as defined in DIN 51 601. Continued on pages 2 to 8 Beuth Verlag GmbH. Berlin. has the exclusive right of sale for German Standards (DIN-Normen! DIN 45 635 Part 1 1 Engi
9、. Price group 6 06.88 Sales No. O1 06 Page 2 DIN 45 635 Part 11 4 Instrumentation The requirements to be met by the instrumentation are specified in clause 4 and table 1 b) of DIN 45 635 Part 1. ular type of application and site of use, other main oper- ating conditions may also be specified. The re
10、quirements to be complied with when making acoustic measurements shall be regarded as met if the power of the engine under test does not deviate by more than f 10% from the power previously agreed. The ambi- ent and inlet temperature during measurement shall not exceed 320 K. The speed and power of
11、the engine shall be determined in accordance with the acceptance con- ditions specified in IS0 3046 Parts 2 and 3, and stated in the test report together with the temperatures measured and the octane number or cetane number of the fuel, which is to comply with the specifications of the engine manufa
12、cturer. 5 5.1 Object under test 5.1 .I Engine surface noise For the purposes of this standard, engine surface noise is the noise emitted from the surface of an internal combus- tion engine, including any required auxiliary equipment (see DIN 6271 Part l), such as fuel pump, water pump, supercharger,
13、 heater radiator, or radiator-fan system. If one or more items of auxiliary equipment are not fitted directly on the engine, so that the noise emitted by these items is not included in the measurement, this shall be noted in the test report. If the engine is completely or partly enclosed, the sur- f
14、ace of the enclosure including any air ducting compo- nents shall be taken as the engine surface. The orifice noise (inlet and exhaust noise) shall be eliminated during measurement, e.g. by passing the inlet and exhaust noise through pipes into other rooms or into the atmosphere. The noise of driven
15、 machines, gearbox or brakes (such as Froude brakes used for power measurement) shall also be eliminated by screening off, or be treated as background noise. Where this is not pos- sible, it shall be stated in the test report. 5.1.2 Engine surface noise and inlet noise (e.g. in the case of large eng
16、ines) For the purposes of this standard, inlet noise is the noise emitted from the air inlet opening. To measure this noise, the engine shall be equipped as described in subclause 5.1.1 for measuring the surface noise only (the exhaust noise shall be eliminated for this purpose). The inlet condition
17、s (provision of filters, exhaust silencers, etc.) shall be specified in the test report. 5.1.3 Engine surface noise including inlet and exhaust noise (e.g. in the case of small engines) Object under test and test conditions For the purposes of this standard, exhaust noise is the noise emitted from t
18、he exhaust orifice. The engine shall be equipped as described in subclause 5.1.1. The inlet conditions and the type and arrangement of the exhaust pipe shall be specified in the test report. 5.1.4 Orifice noise For the purposes of this standard, orifice noise is the generic term covering both inlet
19、and exhaust noise. See appendix A for method of determining The orifice noise. 5.2 Operating condition of engine Where possible, an operating condition conforming to a “main operating condition“ as specified in DIN 45 635 Part 1, in which the engine is operated at its continuous power and at the cor
20、responding speed, shall be selected for the noise measurement, the continuus power being converted to the standard reference conditions (IS0 standard power output as specified in DIN 6271 Part 1). Since, in practice, one and the same engine may be oper- ated under different conditions, depending on
21、the partic- 5.3 Installation of engine The auxiliary devices fitted to the engine under test and required for its operation, as specified in DIN 6271 Part 1, January 1984 edition, appendix A, shall be included in the measurement. Any departures from this requirement shall be stated in the test repor
22、t, together with the types of gearbox and machine used for loading the engine. The noise emitted from gearboxes or from the driven machine shall be regarded as background noise. Suitable measures shall be taken to ensure that this back- ground noise does not raise the total noise level by an amount
23、more than is permissible for the relevant accu- racy grade. During measurement, the engine shall prefer- ably be mounted on a resilient mounting base, any por- tion of the sound emitted from that base or from an adjoining structure being treated as background noise. 5.4 Reference box, measurement su
24、rface, measurement distance and measuring points 5.4.1 Reference box and measurement surface A hypothetical reference surface in the form of the smallest possible rectangular parallelepiped (reference box) enclosing the engine shall be used, protruding com- ponents that are not significant radiators
25、 of sound energy being ignored. For safety reasons, the reference box may be enlarged so as to include hazardous zones, e.g. moving parts on a stationary machine. The measurement surface shall be conformal to the reference box, at measurement dis- tance d, and shall terminate on the sound reflecting
26、 planes at the installation site (e.g. on the floor) or shall itself form a closed enveloping surface (e.g. in semi- anechoic rooms with absorbant floors). The microphone positions shall lie on this measurement surface. 5.4.2 Measurement distance The measurement distance between the reference box an
27、d the measurement surface, d, shall be 1 m, with a minimum of 0,5 m. A distance larger than 1 m may only be used if the environmental requirements specified in DIN 45 635 Part 1 are complied with. 5.4.3 Number and arrangement of measuring points The measuring points shall be evenly distributed on th
28、e measurement surface so as to ensure a complete coverage of the sound field. Their number and arrangement, which are a function of the engine size, the degree of uniform- ity of the sound field and of dimensions 11, Z2 and 1, of the reference box, shall be as shown in figures 1 to 4. DIN 45 635 Par
29、t 11 Page 3 The arrangement of measuring points shall be the same for grade 2 and grade 3 accuracy, the arrangement shown in figures 2,3 and 4 having been simplified in comparison with that specified in DIN 45 635 Part 1. Preliminary measurements have shown that a measure- ment using this simplified
30、 arrangement of measuring points gives results (with maximum deviations of * 1 dB) which are almost identical to those obtained with meas- urement using the complete set of measuring points described in DIN 45 635 Part I. The arrangement of measuring points for small engines (11 and 1, not exceeding
31、 2 m and l3 not exceeding 2.5 m) is shown in figure 1 (basic arrangement with nine meas- uring points). If preliminary measurements on a compar- able type of engine show that the A-weighted sound power level determined by measurements at only five measuring points (points 1, 2,3,4 and 9 in figure 1)
32、 always lies by a fixed level difference, ALw), above the value obtained with the arrangement using 9 meas- uring points, the simplified arrangement (5 points) may be used and ALwA deducted from the measured sound power level. If one of the measuring points shown in the figures can- not be used for
33、lack of space or for other reasons, it shall be displaced on the measurement surface in its measure- ment plane so that the distance from the specified meas- urement site is as small as possible. The position of the measuring point so modified and the reasons for moving it shall be stated in the tes
34、t report. The measuring points in the vicinity of the inlet or exhaust orifice shall be arranged so that the gas stream does not impinge on the microphone. 5.5 Test environment 5.5.1 Reflection properties of test environment To obtain a test result of grade 2 accuracy, a test envi- ronment is requir
35、ed with an environmental correction, K2*, not exceeding 2 dB. This correction shall be deter- Figure 1. Arrangement of measuring points (9 meas- uring points) and measurement surface for internal combustion engines with a reference box having the following dimensions: 1, 5 2 m; 1, 5 2 m; I, 525 m mi
36、ned as specified in subclause B. 2.1 or B. 2.2, item a) or b) of DIN 45 635 Part 1. To obtain a test result of grade 3 accuracy, a test envi- ronment is required with an environmental correction, K2*, not exceeding 7 dB. In many cases, owing to the acoustic characteristics of the test room and the t
37、est bed (mainly in the case of large engines) only grade 3 accuracy can be achieved. By agreement with the customer or the inspection body, however, the accuracy may be improved by using special methods of measurement (e.g. measurement of sound intensity). Noise generated by wind at the microphones
38、shall be deemed to be background noise. For measurements made in the open air, the wind velocity shall be less Figure 2. Arrangement of measuring points (12 measuring points) and measurement surface for internal combustion engines with a reference box having the following dimensions: 11 between 2 an
39、d 4 m; 1, I2 m; 1, I 2,5 m l) Numerous investigations have shown that ALwa is equal to about 1,5 dB. Page 4 DIN 45 635 Part 11 Figure 3. Arrangement of measuring points (15 measuring points) and measurement surface for internal combustion engines with a reference box having the following dimensions:
40、 1, 4 m; l2 4 2 m; 134 m; 1, 2 m and/or I, 2,5 m than 6 m/s; any windscreen required should be used in accordance with the data supplied by the micro- phone manufacturer. See DIN 45 635 Part 1 for further information. 5.5.2 Background noise All noise that is not generated by the engine under test or
41、 is directly emitted from components or orifices that do not form part of the object under test (see subclauses 5.1 and 5.3) shall be deemed to be background noise. The measurement method for obtaining grade 2 accuracy may only be used if the background noise correction, Kl, does not exceed 1,3 dB.
42、For grade 3 accuracy, this correction shall not exceed 3 dB (see clauses 6 and 7). 6 Test procedure 6.1 General The environmental conditions may have an adverse effect on the microphone used. Allowance shall be made for detrimental influences (e.g. strong electric or magnetic fields, wind, impingeme
43、nt of air discharge from the engine under test, temperature) by correctly selecting and/or positioning the microphone. At the measuring points, the microphone shall be oriented with its main axis of sound incidence perpendicular to the measure- ment surface, but, at the corner measurement points, po
44、inted towards the corresponding corner point of the reference box and at the edges, pointed in the direction of the shortest distance between the measuring point DIN 45 635 Part 11 Page 5 Difference between sound pressure level measured wim the engine running and back- level alone, AL, in dB ground
45、sound and the corresponding edge of the reference box. To minimize the possibility of interference caused by the person making the measurement, the microphone should preferably be mounted on a stand and connected to the sound level meter by a cable, the distance between the level meter and the perso
46、n and the microphone being at least 1.5 m. Correction KI, to be deducted from the sound pressure leve measured with the engine running, to obtain the sound pressure level of the engine, in dB 6.2 Measurements using a sound level meter Measurement with a sound level meter shall be made using the time
47、 weighting characteristic “slow“. If the fluctuations in A-weighted sound power level are less than * 3 dB, the noise level shall be considered to be steady, the level being taken as the average of the maxi- mum and minimum levels during the period of observa- tion. Where these fluctuations are grea
48、ter than 2 3 dB, the noise level shall be considered to be non-steady. I 3 3.0 5 6 7 8 9 10 10 4 1 6.3 Measurements using RC-smoothing Where true integration systems are used, the integration time shall be equal to the measurement time. or integrating systems 6.4 Measurements with engine running Onc
49、e the measurement surface has been determined, the correct microphone position has been selected and the steady-state operating condition of the engine has been reached, the A-weighted total level and, where required, the octave band or one-third octave band sound pressure level (for the frequency range of interest) shall be meas- ured for each microphone position, with the engine in operation, simultaneous measurement at all microphone positions not being required. For each measuring point, the measurement time shall be not less than four seconds for all measurements. 6.5 Measuremen
