ChinaAutoRegs|GB/T 14365-1993英文版翻译 声学 机动车辆定置噪声测量方法
ACOUSTICS – MEASUREMENT OF NOISE EMITTED BY STATIONARY ROAD VEHICLES
现行适用版为GB/T 14365-2017《声学机动车辆定置噪声声压级测量方法》。
1. SUBJECT MATTER AND SCOPE
This Standard specifies the test method for the determination of noise emitted by stationary road vehicles in all categories. Stationary means vehicle is not in motion with engine in idle condition. The results obtained by the method stipulated in this Standard can be used to evaluate and verify the main noise source of motor vehicles − noise being measured in proximity to the exhaust and noise near engine. However, the results obtained directly from the test using this method cannot be used for marking the maximum noise level of moving vehicles.
2. NORMATIVE REFERENCES
GB/T 3785-83 − Electric, sonic properties and measuring methods for sound level meters
3. TEST ENVIRONMENT
3.1. Test Site
3.1.1. Any open space may be considered as a suitable test site if it consists of a flat area made of concrete, asphalt or hard materials. The edges of the test site shall be at least 3 m from the extremities of the vehicle (See Figure 1 and Figure 2). Any significant obstacles outside the test site, for example, stationary vehicles, buildings, advertisement board, trees and parallel walls, etc. shall in addition not be closer than 3 m to the microphone during the test.
3.1.2. With the exception of the observer and driver, no person whose presence influences the meter reading shall remain in the site during the test.
3.2. Background Noise
3.2.1. The level of background noise (including any wind) at each measurement position shall be at least 10 dB less than the levels measured during the tests. The background noise in this standard means noise outside the vehicle.
3.2.2. In case the level of background noise is 6 to 10 dB(A) lower than the levels measured, the results measured shall be corrected by deducting the value given in Table 1. The test results are deemed invalid if the difference is lower than 6 dB(A).
3.3. Wind Speed
3.3.1. Windproof cover shall apply to the sound level meter if the wind speed is greater than 2 m/s.
In the meantime, care needs to be taken to avoid the influence of gusts of wind noise during the test.
3.3.2. The test results are deemed invalid if the wind speed is greater than 5 m/s.
4. INSTRUMENTATION
4.1. Instrumentation for Acoustical Measurements
4.1.1. The sound level meter (or the equivalent measuring system) shall meet the Type I or II instruments requirements specified in GB 3785.
4.1.2. The measurements shall be made using the frequency weighting “A”, and the fast gear.
4.1.3. The sound level meter shall be calibrated and adjusted according to instructions at the beginning and at the end of each series of measurements. The difference of the two calibrations shall not exceed 1 dB. The precision of the calibrator shall be greater than or equal to ± 0.5 dB.
4.2. Instrumentation for Measuring Engine Speed
The precision of the engine speed meter shall be greater than 3%.
5. TEST PROCEDURE
5.1. Positioning and Preparation of the Vehicle
5.1.1. The vehicle shall be located in the centre of the test area, with the gear in neutral, handbrake applied, and with clutch engaged. In the case of a motorcycle having no neutral gear position, measurements shall be carried out with the rear wheel raised off the ground.
5.1.2. The engine hood (bonnet), windows and doors shall remain shut. On-board air conditioning and auxiliary shall not be in operation.
5.1.3. Engine outlet water temperature and lubricant temperature shall meet the requirements of the manufacturer during the test.
5.2. Number of Measurements
Repeated measurements shall be carried out at each measuring position. The measurements shall be considered valid if the range of three measurements made immediately one after the other is not greater than 2 dB. The arithmetic mean value given by these three measurements shall constitute the result.
5.3. Measurement of Noise in Proximity to the Exhaust (see Figure 1)
5.3.1. Microphone Positions
5.3.1.1. The height of the microphone above the ground shall be equal to that of the outlet orifice of the exhaust gases, but in any case shall not be less than 0.2 m.
5.3.1.2. Unless otherwise indicated by the manufacturer of the sound level meter, its reference axis for free field conditions shall be parallel to the ground and shall make an angle of 45° ± 10° with the vertical plane containing the direction of the gas flow. The microphone shall be placed towards the outlet orifice and located at a distance of 0.5 m from the latter. The microphone shall be placed towards the external side of the vehicle.
5.3.1.3. In the case of a vehicle provided with two or more exhaust outlets spaced not more than 0.3 m apart and connected to a single silencer, only one measurement position shall be used; the microphone position shall be related to the outlet orifice nearest to the external side of the vehicle. When two or more exhaust outlets are at the same level the outlet which is the highest above the ground shall be chosen.
5.3.1.4. For vehicles provided with multiple exhaust outlet orifices spaced more than 0.3 m apart, one measurement shall be made for each outlet as if it were the only one, and the highest level noted.
5.3.1.5. For vehicles with a vertical exhaust, the microphone shall be placed at the height of the exhaust outlet, orientated upwards and with its axis vertical. It shall be placed at a distance of 0.5 m from the side of the vehicle nearer to the outlet orifice.
5.3.1.6. When the vehicle is such that the microphone cannot be placed according 5.3.1.1 and 5.3.1.2, because of the design (for example spare wheel, oil tank, battery), a figure clearly showing the place chosen for the microphone shall be drawn when the measurement is carried out. As far as possible, the microphone shall be placed at a distance greater than 0.2 m from the nearest obstacle and its reference axis for free field conditions shall be orientated towards the exhaust gas orifice.
5.3.2. Engine Operating Conditions
5.3.2.1. The Engine Measuring Speed
− for petrol engine vehicles, except motorcycles, obtain ¾ nr ± 50 r/min;
− for diesel engine vehicles, except motorcycles, obtain ¾ nr ± 50 r/min;
− for motorcycles, obtain ½ nr ± 50 r/min, when nr > 5 000 r/min; Obtain ¾ nr ± 50 r/min, when nr ≤ 5 000 r/min;
Where
nr is the rated engine speed as indicated by the manufacturer.
5.3.2.2. The noise measured during a period of operation consisting of a brief maintenance of the above constant engine speed and as rapidly as possible deceleration from constant speed to idling speed. The highest level only shall be recorded.
5.4. Measurement of Noise near the Engine (see Figure 2)
5.4.1. Microphone Position
5.4.1.1. The height of the microphone above the ground shall be 0.5 m. The microphone shall be placed 0.5 m from the extremities of the vehicle passenger side and pointed towards the vehicle. Its reference axis for free field conditions shall be parallel to the ground and situated in a vertical plane whose position depends on the type of vehicle as follows:
− engine in front: vertical plane pass through the front axle;
− engine at the rear: vertical plane pass through the rear axle;
− engine at the centre and motorcycles : vertical plane pass through the midpoint of the wheel base.
5.4.1.2. For two wheel motorcycles, the microphone shall be placed on the right hand side of the motorcycle in the forward direction. For motorcycle with side car, the microphone shall be placed on the left hand side of the motorcycle in the forward direction. The microphone shall be pointed towards the vehicle and placed at a distance of 0.5 m from the ground and 0.5 m from the external side of the motorcycle.
5.4.2. Engine Operating Conditions
During the test, the engine shall be accelerated from idling speed, as rapidly as possible to achieve the speed specified in 5.3.2, and keep the engine speed as long as is necessary by using an appropriate device. The noise shall be measured during the period specified above. The highest noise level only shall be recorded.
6. DATA PROCESSING
Recording the measuring data into the following table.
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