GB/T 22036-2017 PDF in English
GB/T 22036-2017 (GB/T22036-2017, GBT 22036-2017, GBT22036-2017)
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Coast-by methods for measurement of tyre-to-road sound emission
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GB/T 22036-2017: PDF in English (GBT 22036-2017) GB/T 22036-2017
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 83.160.10
G 41
Replace GB/T 22036-2008
Coast-by methods for measurement of tyre-to-road sound
emission
(ISO 13325:2003, Tyres - Coast-by methods for measurement of tyre-to-road
sound emission, MOD)
ISSUED ON: DECEMBER 29, 2017
IMPLEMENTED ON: NOVEMBER 1, 2018
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of PRC;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative references ... 6
3 Terms and definitions ... 7
4 General rule ... 7
5 Test site ... 7
6 Measuring instruments ... 8
7 Meteorological conditions and background noise ... 10
8 Preparation and adjustment of tyres ... 11
9 Test road verification ... 12
Appendix A (Normative) Vehicle method ... 13
Appendix B (Normative) Trailer method ... 19
Coast-by methods for measurement of tyre-to-road sound
emission
1 Scope
This standard specifies the test method for measuring the noise of the tyre mounted on
a test vehicle or trailer under coast-by conditions. Coasting refers to the condition in
which the engine is off, there is no power drive, the transmission is in neutral, and the
test tyre is in a free rolling state. The tyre noise test results of the vehicle method are
closer to the actual effect than the trailer method, but the tyre noise is affected by the
suspension parameters; the trailer method test results are closer to the actual noise
produced by a single tyre.
This standard applies to new passenger car tyres and truck tyres. It is neither suitable
for measuring the tyre noise (sound field distribution) of vehicles under normal driving
conditions, nor is it suitable for measuring the traffic noise and the degree of harm of
vehicles at a given position under normal driving conditions.
2 Normative references
The following documents are essential to the application of this document. For the dated
documents, only the versions with the dates indicated are applicable to this document;
for the undated documents, only the latest version (including all the amendments) is
applicable to this standard.
GB/T 3785.1-2010 Electroacoustics - Sound level meters - Part 1: Specifications
(IEC 61672-1:2002, IDT)
GB/T 6326 Tyre terms and definitions (GB/T 6326-2014, ISO 4223-1:2002,
Definitions of some terms used in tyre industry - Part 1: Pneumatic tyres, NEQ)
GB/T 15173-2010 Electroacoustics - Sound calibrators (IEC 60942:2003, IDT)
ISO 362.1 Measurement of noise emitted by accelerating road vehicles - Engineering
method - Part 1: M and N categories
ISO 10844 Acoustics - Specification of test tracks for measuring noise emitted by
road vehicles and their tyres
requirements of GB/T 3785.1-2010 and GB/T 15173-2010 at intervals not exceeding 1
year.
When the wind speed reaches 2 m/s or more, the microphone shall use a windshield.
The test site and the road surface shall comply with the requirements of ISO 10844, as
shown in Figure 1. In addition, there are no acoustic reflectors within the radius shown
in Figure 1.
6.2 Microphone
Two microphones shall be used in the test, one on each side of the vehicle (or trailer).
There shall be no acoustic reflectors near the microphones, and no person shall stand
between the sound source and the microphones. The observer who makes the
measurement shall also stand at least 20 m away from the microphone so as not to affect
the measurement results of the instrument.
The microphone shall be located 1.2 m±0.02 m above the ground and 7.5 m±0.05 m
from the centerline of travel of the vehicle. Its reference axis shall be horizontal and
perpendicular to the centerline of travel of the vehicle.
6.3 Temperature measurement
6.3.1 General remarks
For air and test road surface temperatures, the accuracy of the thermometer or other
temperature-measuring instruments shall be within ±1 °C. Infrared thermometers
cannot be used to measure air temperature.
The type of temperature sensor used shall be documented.
The temperature can be continuously recorded by instruments and equipment. If
conditions are not available, single values can be measured and recorded.
Air temperature and test road surface temperature measurements are mandatory, and
the final readings shall be rounded to the nearest integer of degrees Celsius from the
actual measured value.
Whether it is the vehicle method or the trailer method, the temperature measurement
shall be throughout the whole process of the tyre noise measurement, or the average
value of the temperature at the beginning and end of the test shall be used.
6.3.2 Air temperature
The temperature sensor shall be placed in a sheltered place near the microphone, e.g.,
it is exposed to air currents and out of direct sunlight; a sunshade screen or similar
device can be used to achieve the same effect. The temperature sensor shall be located
1.2 m±0.1 m above the test road surface to reduce the influence of low airflow caused
by heat radiation from the test road surface.
6.3.3 Test road surface temperature
The temperature sensor shall be placed in a position where the temperature is
representative of the temperature in the wheel tracks, without interfering with the
measurement of the tyre noise.
If a contact temperature sensor is used, an adhesive with good thermal conductivity
shall be used between the road surface and the sensor to ensure adequate thermal
conduction.
If a thermal radiation thermometer is used, the height shall be chosen to ensure that a
measuring spot that is ≥0.1 m from the thermometer is covered.
The test road surface shall not be artificially cooled before and during the test.
6.4 Measurement of the wind speed
The accuracy of the anemometer shall be within ±1 m/s. The anemometer shall be at
the height of the microphone, between A-A and B-B, and not more than 20 m from the
centerline of travel (see Figure 1); it shall record the wind direction at the same time.
6.5 Measurement of the speed
The speed measuring device shall be able to test the speed of the test vehicle or trailer
and ensure that the error is within ±1 km/h.
7 Meteorological conditions and background noise
7.1 Meteorological conditions
Measurements shall be taken in good weather conditions. During the test, the wind
speed at the height of the microphone shall not exceed 5 m/s. When the air temperature
is within the range of 5 °C to 40 °C or the road surface temperature is within the range
of 5 °C to 50 °C, the test can be carried out. It shall be noted that the measurements
shall not be affected by gusts of wind.
7.2 Temperature correction
The temperature correction is only applicable to passenger car tyres and truck tyres (the
Appendix A
(Normative)
Vehicle method
A.1 Overview
A.1.1 Test vehicle
The test vehicle shall have two axles, each with two tyres, and shall be able to withstand
the load specified in A.1.4.
A.1.2 Wheelbase
The wheelbase between the two axles on which the test tyres are installed shall be:
a) ≤3.5 m, suitable for passenger car tyres.
b) ≤5.0 m, suitable for truck tyres.
A.1.3 Measures to reduce the impact of the vehicle on tyre noise during the test
In order to ensure that tyre noise is not affected by the structure of the test vehicle, the
following requirements and suggestions shall be put forward for the test vehicle:
a) Requirements:
1) Mudguards or other additional devices shall not be installed;
2) No additional components that may affect noise radiation are allowed near the
edge of the wheel (tyre and rim);
3) Wheel alignment (toe-in of the front wheel, camber of the front wheel, kingpin
caster angle of the vehicle) shall be checked on the vehicle without load, and
it shall fully meet the factory requirements of the vehicle manufacturer;
4) Sound-absorbing materials cannot be installed on the guards around the wheels
or on the bottom of the vehicle;
5) The windows and sunroof of the vehicle shall be closed during the test.
b) Recommendations to avoid additional noise:
a) For passenger car tyres and truck tyres (the single-tyre load index is ≤121 and the
speed category is N and above), the speed shall be 70 km/h~90 km/h.
b) For truck tyres whose single-tyre load index is less than or equal to 121 and the
speed category is M and below or truck tyres whose single-tyre load index is ≥122,
the speed shall be 60 km/h~80 km/h.
See A.2.2 for relevant reference speeds.
A.1.8 Determination of test data (A-weighted sound level)
Each time the test vehicle passes between the A-A line and the B-B line, the maximum
sound pressure level of the two microphones shall be recorded.
If there is a significant difference (abnormal) between the recorded maximum sound
pressure level and the actual sound pressure level, the measurement is invalid. For
example, under the same speed conditions, repeated tests are carried out many times,
and the repeatability of the results is poor (the maximum A-weighted sound level varies
greatly), then the measurement is considered invalid.
A.1.9 Number of measurements
For each microphone located on the left and right sides, the measuring shall be carried
out at least 4 times at a speed higher than the reference speed (see A.2.2), and at least 4
times at a speed lower than the reference speed. These speeds shall be evenly distributed
within the range of test speeds specified in A.1.7 roughly. It shall be ensured that the
measuring is carried out with the reference speed used as the standard for 4 times.
A.1.10 Recommended frequency spectrum measurement
It is recommended to measure the one-third-octave band frequency spectrum curve of
“A” frequency weighting characteristic at the same time, and the result shall be
consistent with the result of “F” time weighting characteristic. The data shall be the
one-third-octave band frequency spectrum curve corresponding to the maximum A-
weighted sound level when the vehicle passes by.
A.2 Data processing
A.2.1 Temperature correction
See 7.2.
A.2.2 Reference speeds
In order to obtain the standard noise at a certain speed, the reference speed Vref is defined
Appendix B
(Normative)
Trailer method
B.1 Towing vehicles and trailers
B.1.1 Overview
The test equipment consists of a towing vehicle and a trailer.
B.1.1.1 Towing vehicle
B.1.1.1.1 A-weighted sound level
The rolling sound of the towing vehicle can be minimized by appropriate measures,
such as the use of low-noise tyres, shielding, and aerodynamic skirts. Ideally, the A-
weighted sound level of the tyre measured in the towing vehicle test is at least 10 dB(A)
lower than the A-weighted sound level measured in the combination test of the towing
vehicle and the trailer. In this case, multiple measurements on the towing vehicle alone
are not necessary. Since the noise emitted by the towing vehicle does not need to be
deducted, the measurement accuracy of the noise emitted by the trailer tyres can be
greatly improved. The A-weighted sound level difference and the A-weighted sound
level of the tyre shall be recorded.
B.1.1.1.2 Load
In the combination test of the towing vehicle and the trailer and the test of the towing
vehicle only, the load on the tyres of the towing vehicle shall not change. In order to
obtain a constant load, a counterweight shall be added during the test of the towing
vehicle alone.
B.1.1.2 Trailer
B.1.1.2.1 Single-axle trailer
The trailer shall be a single-axle, two-wheel trailer with a drawbar and facility for
varying wheel loads. In order to minimize the impact of baffle reflections, closed floors
and paneling cannot be used. The tyres shall be exposed, not covered by tyre covers or
mudguards.
B.1.1.2.2 Drawbar length
B.3 Measurement procedure
B.3.1 Overview
In this test, two sets of measurements shall be made:
a) Carry out the towing vehicle test alone, and record the measured A-weighted
sound level according to the following procedure.
b) Carry out the combination test of towing vehicle and trailer, and record the test
results of the A-weighted sound level.
B.3.2 Vehicle position
The towing vehicle or towing vehicle and trailer combination shall approach the line E-
E with the engine off (the transmission in neutral and the clutch disengaged), and the
centerline of the vehicle shall be as close as possible to the centerline of the travel, as
shown in Figure B.1.
B.3.3 Reference speed
Before the towing vehicle enters the test zone (E-E or F-F, as shown in Figure B.1), it
shall reach a sufficient speed, so that when the engine of the towing vehicle is turned
off, the vehicle and the trailer can coast into the test zone. Between A-A and B-B, for
passenger car tyres and truck tyres (the single-tyre load index is less than or equal to
121 and the speed category is N and above), the reference speed shall be (80±1) km/h;
for truck tyres whose single-tyre load index is less than or equal to 121 and the speed
category is M and below or truck tyres whose single-tyre load index is 122 and above,
the reference speed shall be (70±1) km/h.
B.3.4 Data collection
B.3.4.1 Noise measurement
In the test zone between A-A and B-B, as shown in Figure B.1, the sound pressure level
and maximum sound pressure level of the tyre that vary with the position and the time
during the test shall be recorded throughout the test. In addition, during the test tyre
passes through the entire measurement area, it is necessary to record the sound pressure
level of each microphone based on the F weighing time interval of no more than 0.01
s. In the subsequent analysis, this latter set of data will be used as the time history sound
pressure level.
The time history measurement starts when the trailer is at the A-A line and ends when
it is at the B-B line (see Figure B.1).
a) Preparation:
1) Set the time trigger point on the trailer.
2) Measure the distance from the trailer to the towing vehicle.
3) As shown in Figure B.1, determine the locations of E-E, A-A, P-P, B-B, and F-
F on the test site; set the trigger device so that the sound pressure level
recording begins at E-E and stops at F-F.
4) For passenger car tyres and truck tyres (the single tyre load index is less than
or equal to 121 and the speed category is N and above), the reference speed
between A-A and B-B shall be (80±1.0) km/h; for truck tyres whose single tyre
load index is less than or equal to 121 and the speed category is M and below
or whose single tyre load index is 122 and above, the reference speed shall be
(70±1.0) km/h. Measure the speed of the test tyre from A-A to B-B, which is
equivalent to the section from A-A to B-B displayed by the trailer’s time
indicator.
5) Set the data collector so that the time history is always from E-E to F-F for the
towing vehicle alone test or the combination test of the towing vehicle and the
trailer. According to B.3.6, set the trigger to generate the indication pulse when
P-P is reached, and compare the time history records.
6) Check air temperature and wind speed measuring instruments.
b) Solo test (towing vehicle alone), at least five times:
1) When the towing vehicle passes each microphone position, record the
maximum A-weighted sound pressure level and the time history of this sound
pressure level; carry out this measurement procedure continuously until the
five maximum sound pressure levels are within ±0.5 dB compared with their
arithmetic mean, and record the position of each microphone.
2) Five time histories shall be temperature-corrected.
3) Use these five time histories to determine the time history of the average sound
pressure level.
4) Carry out 1) to 3) in b) of this test at the beginning and end of each series of
tests. If the air temperature does not change by more than 5 °C during the test
period, the trailer test can be carried out.
c) Combination test (towing vehicle and trailer), at least five times:
1) When the towing vehicle passes each microphone position, record the
maximum A-weighted sound pressure level and the time history of this sound
pressure level; carry out this measurement procedure continuously until the
five maximum sound pressure levels are within ±0.5 dB compared with their
arithmetic mean, and record the position of each microphone.
2) Five time histories shall be temperature-corrected.
3) Use these five time histories to determine the time history of the average sound
pressure level.
B.4 Determination of the sound pressure level of tyre noise
B.4.1 Taking into account the influence of the towing vehicle
Before the calculation of the A-weighted sound level of the coast-by tyre, a test shall be
carried out to ensure the data is valid. The difference between the measured values from
the towing vehicle alone test and the combination test of towing vehicle and trailer shall
be sufficient enough to ensure accurate calculation of the A-weighted sound level of the
tyre.
This difference is judged by the following two methods.
a) Maximum sound pressure level difference ≥10 dB
For two microphones, if the average value of the maximum A-weighted sound level
of the towing vehicle alone is at least 10 dB less than the average value of the
maximum A-weighted sound level of the towing vehicle and trailer combination,
then the measurement is valid; it means that all environmental conditions and
background sounds, etc. have met the requirements. In this case, the A-weighted
sound of the tyre level is the average value of the maximum A-weighted sound levels
measured during the combination test of the towing vehicle and the trailer, as shown
in the formula (B.2):
where:
Ltyre --- A-weighted sound level of the test tyre (that is, the value in the report).
b) Maximum A-weighted sound level difference < 10 dB
For one or two microphones, if the difference between the average maximum sound
pressure level of the towing vehicle alone and the average maximum A-weighted
alone and the combination (towing vehicle and trailer) are correct; if the difference is
< 10 dB, then the tyre A-weighted sound level is calculated by the logarithmic
subtraction of the combination (towing vehicle and trailer) and the towing vehicle sound
pressure levels as given in the following formula. For this logarithmic subtraction, the
average time history values noted in Figure B.2 above are applied. The tyre A-weighted
sound level in the report is the calculation result of the formula (B.3).
where:
LTP --- The maximum A-weighted sound level of the test pass (the combination of
towing vehicle and trailer);
LT --- A-weighted sound level measured by the towing vehicle at the same position
as LTP without a trailer.
B.4.3 Determination procedure of sound pressure level
If the average maximum A-weighted sound level of the combination (towing vehicle
and trailer) measured by the left and right microphones is 10 dB greater than the average
maximum A-weighted sound level of the towing vehicle alone, then the sound pressure
level of the combination is equal to the tyre A-weighted sound level [as calculated by
steps a), b), and c) in B.3], the following procedures are unnecessary.
If the difference is less than 10 dB, proceed as follows:
a) Align the appropriate solo towing vehicle and the combination average A-
weighted sound level time histories and determine the arithmetic difference for
each increment in time. Record the A-weighted sound level difference at the point
of the maximum sound pressure level of the combination (towing vehicle and
trailer). Repeat this step for each test.
If the difference is >10 dB, then the A-weighted sound level of the combination
is equal to the A-weighted sound level of the tyre.
b) If the calculated difference is less than 10 dB and greater than 3 dB, determine the
logarithmic difference of the maximum average time history A-weighted sound
levels of the combination (towing vehicle and trailer) and the towing vehicle
alone when the maximum A-weighted sound level of the combination (towing
vehicle and trailer) occurs.
c) If the difference is less than 3 dB, the measurement is invalid. The A-weighted
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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