Specification and test methods for exhaust muffler of motorcycles and mopeds
1 Scope
This standard specifies the technical requirements and test methods, inspection rules as well as marking, packaging, transportation and storage for exhaust muffler of motorcycles and mopeds.
This standard is applicable to exhaust muffler of motorcycles and mopeds.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments to (excluding any corrigendum), or revisions of, any of these publications do not apply. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the latest editions of the standards indicated below. For undated references, the latest edition applies.
GB/T 191 Packaging - Pictorial marking for handling of goods
GB/T 3241 Octave-band and fractional-octave-band filters
GB/T 3785 Electric, sonic properties and measuring methods for sound level meters
GB/T 4570 Test method of durability for motorcycles and mopeds
GB/T 5363 Method of bed test of gasoline engine for motorcycles and mopeds
GB/T 5378 General rules of running test for motorcycles and mopeds
GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values
GB 16169 Limit and measurement method of noise emitted by accelerating motorcycles and mopeds
GB/T 20076 Measurement methods of maximum torque and maximum net power of engines for motorcycles and mopeds
3 Terms and definitions
For the purpose of this standard, the following terms and definitions apply.
3.1
exhaust muffler
integral part used to exhaust the exhaust gas after engine combustion to the atmosphere and effectively reduce the noise of exhaust gas flow
Note: An exhaust muffler generally consists of the integral parts from the exhaust inlet to the exhaust port of the exhaust muffler, including the pollution control device and fiber sound-absorbing materials that may be installed on the exhaust muffler.
3.2
exhaust noise
noise generated when exhaust gas after engine combustion is discharged from exhaust port of exhaust device
3.3
measure of exhaust muffler
measure of engine power and exhaust noise to install the muffler to be test
3.4
hollow pipe
device that has the same boundary dimension and wall thickness as the muffler to be tested, does not contain all internal partitions, internal air ducts and tail end covers of the exhaust muffler, and has all welding process holes of the outer cylinder blocked
3.5
measure of hollow pipe
measure of engine power and exhaust noise to install the hollow pipe to substitute the exhaust muffler
3.6
insertion loss
difference of sound pressure levels of exhaust noise through the exhaust port during measure of hollow pipe and measure of muffler at the speed when the engine reaches the maximum net power, D, expressed in dB(A)
Note: Under normal circumstances, the size, shape and sound field distribution of the pipe orifice remain approximately the same, so the insertion loss is equal to the difference of noise sound pressure levels before and after installing the muffler at a given measuring point.
The insertion loss, D, shall be calculated using Formula (1):
Foreword I
1 Scope
2 Normative references
3 Terms and definitions
4 Technical requirements
5 Test methods
6 Inspection rules
7 Marking, packaging, transportation and storage
Annex A (Informative) Records for testing power loss ratio and insertion loss of exhaust mufflers
Annex B (Informative) Records for testing exhaust noise and insertion loss in each octave band in spectrum analysis
