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Limits and measurement methods for noise emitted by accelerating motor vehicles
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GB 1495-2002: PDF in English GB 1495-2002
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 13.140
Z 32
Replacing GB 1495, partially replacing GB 1496-79
Limits and measurement methods for noise
emitted by accelerating motor vehicles
ISSUED ON. JANUARY 04, 2002
IMPLEMENTED ON. OCTOBER 01, 2002
Issued by. State Environmental Protection Administration;
General Administration of Quality Supervision, Inspection and
Quarantine.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Definitions ... 5
4 Noise limit ... 6
5 Measurement methods ... 7
Annex A (standard) Measurement methods for noise emitted by accelerating
motor vehicles ... 8
Annex AA Requirements for noise measurement test road ... 15
Annex AB Record of measurement for noise emitted by accelerating motor
vehicles ... 23
Limits and measurement methods for noise
emitted by accelerating motor vehicles
1 Scope
This Standard specifies the limits for noise emitted by accelerating new
produced motor vehicles.
This Standard specifies the measurement methods for noise emitted by
accelerating new produced motor vehicles.
This Standard is applicable to Category-M and Category-N1 motor vehicles.
2 Normative references
The following standards contain the provisions which, through reference in this
Standard, constitute the provisions of this Standard. For dated references,
subsequent amendments (excluding corrections) or revisions do not apply to
this Standard. However, the parties who enter into agreement based on this
Standard are encouraged to investigate whether the latest versions of these
documents are applicable.
GB 3785-83, Electroacoustics - Sound level meters
GB/T 15173-94, Sound calibrators
GB/T 12534-90, Motor vehicles - General rules of road test method
ISO 10844-1994, Acoustics - Specification of test tracks for the purpose of
measuring noise emitted by road vehicles 2
ISO 10534 1996, Acoustics - Determination of sound absorption coefficient
and impedance in impedance tubes - Part 1. Method using standing wave
ratio 3
GB/T 17692-1999, Measurement methods of net power for automotive
engines
1 The classification for motor vehicles is in accordance with GB/T 15089-1994 “Classification of power-
driven vehicles and trailers”.
2 This Standard is under the jurisdiction of National Technical Committee on Acoustics of Standardization
Administration of China.
3 This Standard is under the jurisdiction of National Technical Committee on Acoustics of Standardization
Administration of China.
3 Definitions
For the purposes of this document, the following definitions apply.
3.1 Motor vehicle’s category
In terms of noise outside the motor vehicle, a category of motor vehicle refers
to a category of motor vehicles that have no difference in the following main
aspects.
3.1.1 Body shape or structural material (especially the engine compartment and
its sound insulation material).
3.1.2 Length and width of motor vehicle.
3.1.3 Engine type (ignition or compression ignition, two-stroke or four-stroke,
reciprocating or rotary piston), number of cylinders and displacement, number
of carburetor and type or fuel injection system type, valve arrangement, rated
power and corresponding speed; or the category of drive motor (for electric
vehicles).
3.1.4 Drive train, gear number and its speed ratio.
3.1.5 Noise reduction system or components as defined in 3.2 and 3.3 below.
3.1.6 For vehicles other than Category-M1 and Category-N1, if the difference
between 3.1.2 and 3.1.4 does not result in a change in the noise measurement
method (such as gear selection), the engine of the same type and (or) when
the total transmission ratio is different, it can be regarded as the same category.
3.2 Noise reduction system
Noise reduction system refers to the complete set of components necessary to
limit the motor vehicle and its exhaust noise. When the noise reduction
component’s designations or trademarks in the system are different, or the size
and shape of the components, material properties, assembly, working principle
are different, or the number of intake/exhaust mufflers is different, the system
shall be regarded as different types of noise reduction systems.
3.3 Noise reduction system components
The noise reduction system component refers to one of the individual
components that constitute the noise reduction system, such as the exhaust
pipe, the expansion chamber, the muffler, etc. It is considered a component of
the noise reduction system when the presence of the air filter is essential to
ensure that the specified noise limits are met. The exhaust manifold shall not
be considered as a component of the noise reduction system.
Annex A
(Normative)
Measurement methods for noise emitted by accelerating motor vehicles
A.1 Measuring instruments
A.1.1 Acoustic measurement
A.1.1.1 The sound level meter for measurement or other equivalent
measurement system shall not be lower than the requirements of the Type 1
sound level meter specified in GB 3785. “A” frequency weighting characteristics
and “F” time weighting characteristics shall be used for measurement. When
using a system that automatically samples and measures the A-weighted sound
level, the reading interval shall not exceed 30 ms.
A.1.1.2 Before and after measurement, the sound level meter must be
calibrated according to the manufacturer's specifications with a Level 1 acoustic
calibrator in accordance with GB/T 15173. If no adjustment is made, if the
difference between the previous calibration reading and the previous calibration
reading exceeds 0.5 dB, the measurement result after the previous calibration
is considered invalid. The readings during calibration shall be recorded in the
form in Annex AB.
A.1.2 Measurements of rotating speed, vehicle speed
An engine tachometer or vehicle speed measuring instrument with an accuracy
better than ±2% must be used to monitor the rotating speed or vehicle speed.
Do not use the same type of instrument on the vehicle.
A.1.3 Meteorological parameter measurement
The accuracy of the thermometer shall be within ±1°C. The accuracy of the
anemometer shall be within ±1.0 m/s.
A.1.4 All measuring instruments shall be periodically inspected in accordance
with the relevant national standards for measuring instruments.
A.2 Measuring conditions
A.2.1 Measuring site
A.2.1.1 The sound field conditions that shall be achieved at the measuring site
(see Figure 1) are. when placing a non-directional small sound source at the
center of the site (point O), the sound level deviation in all directions on the
hemisphere does not exceed ±1dB. If the following conditions are met, the
venue can be considered to have reached this sound field condition.
a) there are no large acoustic reflectors, such as fences, rocks, bridges or
buildings, within a radius of 50m based on the center of the measurement
site (point O);
b) the surface of the test road and the rest of the site are dry, and there is no
sound absorbing material such as snow, tall grass, loose soil or slag;
c) there are no obstacles affecting the sound field near the microphone, and
no one is standing between the sound source and the microphone; the
observer conducting the measurement shall also be in a position that does
not affect the measured value of the instrument.
A.2.1.2 The measurement site shall be substantially horizontal, solid, and flat,
and the test road shall not produce excessive tire noise. This road surface shall
meet the requirements of Annex AA
A.2.2 Meteorological conditions
Measurements shall be carried out in good weather. The wind speed at the
height of the microphone shall not exceed 5 m/s when measuring. Note that the
measurement results are not affected by gusts. A suitable hood can be used,
but its influence on the sensitivity and directionality of the microphone shall be
considered.
The measuring instrument for meteorological parameters shall be placed near
the measuring site with a height of 1.2 m.
A.2.3 Background noise
The background noise (A-weighted sound level) shall be at least 10 dB lower
than the measured vehicle noise.
A.2.4 Vehicle
A.2.4.1 The vehicle to be tested shall be empty, without trailer or semi-trailer
(except for vehicles that cannot be decomposed).
A.2.4.2 The tires used in the vehicle to be tested are selected by the vehicle
manufacturer and must be one of the types specified for the vehicle. The tires
with any partial depth less than 1.6 mm must not be used. The tire must be
charged to the factory's no-load air pressure.
A.2.4.3 Before starting the measurement, the technical condition of the vehicle
under test shall comply with the technical conditions of the vehicle (especially
the acceleration performance of the vehicle) and the relevant provisions of GB/T
A.3.2 Determinations of vehicle gear selection and approach speed
The meanings of the symbols used in this article are as follows.
S. Engine rated rotating speed;
NA. Steady rotating speed of the engine when approaching Line AA’.
A.3.2.1 Manual transmission
A.3.2.1.1 Gear selection
a) For M1 and N1 vehicles, when using a transmission with no more than four
forward gears, apply the second gear for measurement;
b) For M1 and N1 vehicles, when using a transmission with more than four
forward gears, measurements shall be made in the second and third gears
respectively.
If the engine speed exceeds S when passing Line BB' when measuring
with the second gear, the NA shall be reduced by 5%S successively until
the engine speed exceeds S through Line BB'. If the NA drops to idle speed
and the speed through Line BB' still exceeds S, then only the third gear is
used.
However, for M1 vehicles with more than four forward gears and engines
with a rated power greater than 140kW and a rated power/maximum mass
ratio greater than 75 kW/t, if the vehicle uses the third gear, its tail end
passes Line BB' at a speed greater than 61 km/h, only the third gear shall
be used for measurement.
c) For vehicles other than M1 and N1, vehicles with a total number of forward
gears X (including speed ratios obtained by the auxiliary or multi-speed
ratio drive axle) shall be measured separately for each gear equal to or
greater than X/n. For vehicles with an engine rated power not greater than
225 kW, take n=2. For vehicles with a rated power greater than 225 kW,
take n=3. If X/n is not an integer, the gear corresponding to the higher
integer shall be selected. The upshift measurement is started from the X/n
gear until the engine speed is first lower than the rated speed when the
tail passes Line BB' at the end of the gear.
NOTE. If the main transmission has eight speed ratios and the auxiliary transmission has two
speed ratios, the drive train has 16 gear positions. If the rated power of the engine is 230 kW,
then . Then the gear that starts to measure is the sixth gear (that
is, the sixth gear of the 16 gears obtained by the main and auxiliary transmission combination),
the next measurement gear is the seventh gear, and so on.
A.3.2.1.2 Determination of approach speed
30, 40, 50 km/h (if the maximum speed of the lane is less than 50 km/h, the
maximum speed is 3/4) to Line AA'.
A.3.3 Accelerated driving operation
A.3.3.1 The vehicle shall approach Line AA' at the gear position and steady
speed specified above, and its speed change shall be controlled within ±1 km/h.
If the engine speed is controlled, the speed change shall be controlled within
±2% or ±50 r/min (whichever is greater).
A.3.3.2 When the front end of the vehicle reaches Line AA', the accelerator
pedal must be stepped as quickly as possible (i.e., the throttle or accelerator is
fully open) and remain unchanged until the rear end of the vehicle passes Line
BB' and then the pedal is released as quickly as possible (that is, the throttle or
accelerator is closed).
A.3.3.3 The vehicle shall accelerate in a straight line through the measuring
area, and its longitudinal center plane shall be as close as possible to the center
Line CC'.
A.3.3.4 If the vehicle is composed of a tractor and a trailer that is not easily
separated, it is determined that the tail end does not consider the trailer when
passing Line BB'.
A.3.4 Sound level measurement
A.3.4.1 At least four measurements shall be performed on each side of the
vehicle.
A.3.4.2 The maximum sound level of the vehicle that accelerates through the
measurement area shall be measured. The measured value of each
measurement shall be subtracted by 1 dB(A) as the measurement result.
A.3.4.3 If the difference between four consecutive measurements on the same
side of the vehicle is not more than 2 dB (A), the measurement is considered
valid.
A.3.4.4 Take arithmetic average of four measurements on each side under each
gear (or near speed) condition. Then take the larger of the averages on two
sides as the intermediate result.
A.3.5 Determination of maximum noise level of vehicle
A.3.5.1 Corresponding to the gear condition of a) in A.3.2.1.1, directly take the
intermediate result as the maximum noise level.
A.3.5.2 Corresponding to the gear condition of b) in A.3.2.1.1, if the second and
third gears are used, the arithmetic mean of the intermediate results of the two
Annex AA
Requirements for noise measurement test road
AA1 Introduction
This Annex, based on the main content of ISO 10844.1994 “Acoustics --
Specification of test tracks for the purpose of measuring noise emitted by road
vehicles”, specifies technical requirements for test road construction and
physical properties to be achieved and their measurement methods.
AA2 Terms
This Annex adopts the following terms.
AA2.1 Void ratio
Void ratio refers to the percentage of pore volume between aggregates in road
concrete to the total volume of concrete, expressed as Ve. These pores are
either interconnected (closed pores) or open to the surrounding atmosphere
(open pores). The void ratio of the test road is determined by the following
formula based on the obtained core sample.
Where,
ρA - Apparent density of core sample;
ρR - Maximum theoretical density of core sample.
The apparent density ρA is determined by the following formula.
ρA = m/V
Where,
m - Mass of the core sample obtained by test road;
V - Volume of this core sample, excluding air volume of the opening gap of the
road surface.
The density is determined according to the mass and volume of the binder
contained in each core sample, the mass and volume of the aggregate, given
by.
If the road surface does not meet the void ratio requirements, its sound
absorption coefficient must meet. α≤0.10. See AA3.5.2 for its measurement
method.
NOTE. Although road builders are more familiar with void ratio, the most relevant characteristic
is the sound absorption coefficient. However, the sound absorption coefficient is measured only
when the void ratio cannot meet the requirements. Because the measurement and correlation
of void ratio have large uncertainties, it is possible to erroneously negate certain roads based
solely on the measurement of void ratio.
AA3.3 Road surface construction depth
The average road surface construction depth measured by volume method
shall meet. MTD≥0.4mm, the measurement method can be found in AA3.5.3.
AA3.4 Road uniformity
It is necessary to ensure that the road surface depth and void ratio of the road
surface in the test area are as uniform as possible.
NOTE. It shall be noted that if the rolling effect is different in some areas, the
road surface construction shall be different and shall be uneven.
AA3.5 Inspection cycle
In order to check whether the road has consistently met the requirements of the
road surface construction depth, void ratio or sound absorption coefficient
specified in this Annex, periodic road inspection shall be carried out at the
following intervals.
a) For void ratio or sound absorption coefficient
When the road is newly paved, check once. If the new road meets the
requirements, there is no need to perform periodic inspections. If the new
road surface does not meet the requirements, it can be checked after a
period of time, because the road space shall be blocked and become
dense over time.
b) For road surface construction depth
When the road is newly paved, check once. When starting the noise test
(NOTE. it shall be done 4 weeks after paving). Check once a year after
that.
AA4 Design of test road
AA4.1 Area
Compaction, relative to Marshall
compaction 98%
g) The appropriate mix temperature shall be selected prior to rolling so that
the next void can be achieved to achieve the desired void ratio. In order
to improve the possibility of meeting the technical requirements of AA3.1
to AA3.4, the degree of compaction shall be studied. Not only to study the
right mix temperature, but also to study the appropriate number of passes
and to choose the right rolling machine.
AA5 Measurement methods
AA5.1 Measurement of void ratio
In order to perform this measurement, it is necessary to obtain the paved core
at least 4 locations in the test area between Line AA' line and Line BB' line (see
Figure AA1). In order to avoid causing unevenness or unevenness on the rim,
the core sample shall be taken from the vicinity of the rim and shall not be taken
on it. At least two core samples shall be taken near the rim. One core shall be
taken between the rim and the two microphones.
If the conditions for the homogeneity are not met (see AA3.4), they shall be
taken elsewhere in the test area.
The void ratio of each core sample shall be determined. Then calculate the
average of all core samples. Compare with the requirements of A.3.1. In
addition, there must no core sample with a void ratio greater than 10%. It is
necessary to remind the paver of the test road that problems may arise due to
sampling in the test area where the pipeline or wire is heated. Installation of
these devices must be carefully designed to avoid future sampling locations. It
is recommended to leave some areas of approximately 200 × 300mm without
tubes or wires, or to make them deeper so that they shall not be damaged when
sampling from the road.
AA5.2 Measurement of sound absorption coefficient
Sound absorption coefficient (normal incidence) is measured by impedance
tube, the method is in accordance with ISO 10534-1.
The requirements for sampling are the same as for the measurement of void
ratio (see AA5.1). The sound absorption coefficient is measured in the
frequency range of 400 to 800 Hz and 800 to 1600 Hz (at least at the center
frequency of the octave). The maximum of these two frequency ranges shall be
measured. Then, calculate the average the measurements of all core samples,
using the average as the final result.
AA5.3 Measurement of road surface construction
Depth measurement of road surface construction shall be carried out at 10
locations on the rim of the test runway. After averaging, compare with the
specified minimum depth. The measurement method is detailed in Annex A of
ISO 10844.
AA6 Stability and maintenance over time
AA6.1 Aging effect
As with any other road surface, the tire/road noise level measured on the test
surface may increase slightly during the 6~12 months’ period after the paving
is completed. The road shall reach the required characteristics after four weeks
of paving. The effect of this aging on the noise of trucks is generally less than
the impact on passenger cars. The stability of the road surface over time
depends mainly on the degree of calendaring and compaction of the vehicle on
the road. Periodic inspection shall be carried out in accordance with the
provisions of AA3.
AA6.2 Road maintenance
Loose gravel or dust that significantly reduces the depth of the effective road
surface construction shall be removed. In the winter when it is frozen, no salt
shall be used to prevent freezing. Salt may temporarily or permanently change
the characteristics of the road surface and cause noise increase.
AA6.3 Resurfacing road in test area
Resurface the road area if necessary. If the test area other than the test track
(width as 3 m shown in Figure AA1) meets the requirements for void ratio or
sound absorption coefficient, there is no need to resurfacing it.
AA7 Report on test road and noise test
AA7.1 Report on road check
AA7.1.1 Test runway position
AA7.1.2 The type of bitumen, the penetration, the type of stone, and the
maximum theoretical density (DR) of concrete are taken from the thickness of
the wear layer and the grading curve determined by core sample of test runway.
AA7.1.3 Compaction method (type of roller compactor, weight of mill and
number of crushing).
AA7.1.4 Mixture temperature, ambient temperature and wind speed during
paving.
AA7.1.5 Pavement paving date and contractor
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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