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Quality inspection of products for motorcycles and mopeds Quality evaluation method of exhaust muffler
1 Subject content and applicable scope
This standard specifies the performance evaluation method of exhaust muffler for motorcycles and mopeds by sampling inspection.
This standard is applicable to performance sampling inspection, supervision and management, grade evaluation and new product identification of exhaust muffler for motorcycles and mopeds.
2 Normative references
GB/T 2828 Sampling procedures and tables for lot-by-lot inspection by attributes
GB/T 3241 Octave and third-octave band filters used for the analysis of sound and vibration
GB/T 3785 Electric, sonic properties and measuring methods for sound level meters
GB/T 5363 Method of bed test of gasoline engine for motorcycles and mopeds
3 Sampling requirements
3.1 Sampling object
Formally approved finished mufflers that are mass-produced or batch-produced in this evaluation period, and have passed the acceptance inspection conducted by the inspection department of the enterprise.
3.2 Sampling method
Random sampling.
3.3 Sampling period
The sampling period is one year for inspection by departments. The sampling period and quantity of self-inspection shall be determined by the enterprise at discretion.
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3.4 Sampling quantity
When the inspection department conducts random sampling inspection from time to time, three mufflers shall be extracted at a time for inspecting performance, leakproofness, appearance and assembly quality (one substitute pipe shall be provided by the manufacturer). One of the three can only be used for testing reliability (vibration resistance).
3.5 Sampling base
For sampling in the finished product warehouse of the manufacturer, the sampling base shall be greater than 20 times the sample size. For sampling in assembly site and users’ places, sampling base will not be restricted.
3.6 Double sampling
Double sampling is not allowed for any inspections, except that one double sampling is allowed for unqualified products identified in factory self-inspection (in the double sampling inspection, twice amount of unqualified samples shall be inspected for unqualified items and related items, and the products subject to double sampling inspection can only be graded as acceptable products or below).
4 Terms
4.1
exhaust muffler
air duct with special structure or sound-absorbing lining that can effectively reduce the exhaust noise of engine
4.2
measure of muffler
measure of engine power and exhaust noise to install the muffler to be tested
4.3
substitute pipe
hollow pipe with the same boundary dimension and wall thickness as the muffler to be tested
4.4
measure of hollow pipe
measure of engine power and exhaust noise to install the substitute pipe
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4.5
insertion loss
difference of sound power levels radiated through the exhaust port during measure of hollow pipe and measure of muffler
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 sound pressure levels before and after installing the muffler at a given measuring point.
4.6
power loss ratio
ratio of the difference between powers obtained in measure of hollow pipe and measure of muffler respectively to the power value obtained in measure of hollow pipe when the carburetor throttle is fully open at the rated speed of the engine
5 Technical requirements
5.1 The muffler assembly, parts and components shall be manufactured according to the drawings and technical documents approved by the prescribed procedures, and shall meet the requirements of this standard. In case of involving its performance, installation and interchangeability, the remodel design of muffler can only be carried out with the consent of the relevant competent department.
5.2 The metal stamping parts of muffler shall meet the technical requirements concerned. External surface shall be subjected to rust-proof treatment.
5.3 Non-metallic parts of muffler shall have corrosion resistance, and can work normally within the service conditions and service temperature range.
5.4 The shell and partition of muffler shall have sufficient rigidity and thickness to prevent regenerative noise caused by airflow and surface radiation noise greater than exhaust noise.
5.5 Muffler and its parts shall be welded firmly with smooth and uniform welds and without obvious welding defects such as lack of weld, blowholes, overlaps, slag inclusion and excessive penetration. They shall also be free of internal foreign matters such as slags.
5.6 The muffler shall have smooth and flat appearance and protective coating on the surface. The surface of such coating shall be firm, uniform in color and free of obvious bumps and abrasions.
5.7 The connection of the inlet end of the muffler and the engine must be sealed reliably and free of air leakage.
1 Subject content and applicable scope
2 Normative references
3 Sampling requirements
4 Terms
5 Technical requirements
6 Test apparatus
7 Test items
8 Test methods
9 Evaluation method
Additional explanation:
