Chongqing Cummins Diesel Generator Set Diesel Engine Class 3 Noise

With the rapid development of the national economy, the gap in urban and rural power supply is growing larger, and the number of diesel generator sets is increasing day by day. Especially in large and medium - sized cities with a relatively concentrated population, when diesel generator sets are widely used, their noise has become a noise source that cannot be ignored. The noise of diesel generator sets mainly comes from two major parts: the diesel engine (including combustion noise, mechanical noise, intake noise, exhaust noise, fan noise, and surface radiation noise, etc.) and the generator (including aerodynamic noise, mechanical noise, electromagnetic noise, and transmission noise, etc.). To reduce the noise of generator sets, it is necessary to control the main noise sources, and accurately identifying the main sound sources is the key to control. Dingbo Power, a Chongqing Cummins diesel generator manufacturer, briefly introduces the following content.

Three types of noise from Chongqing Cummins diesel generator sets

1. Intake and exhaust noise

Intake and exhaust noise is the strongest noise source of the diesel engine. Intake noise is mainly caused by the pressure pulsation of air in the intake pipe, generating low - frequency noise; when air flows through the cross - section of the intake valve at high speed, high - frequency eddy - current noise is generated; there is also the noise from the supercharger compressor of a turbocharged diesel engine. Exhaust noise is mainly due to the pressure pulsation of exhaust gas in the exhaust pipe, generating low - and medium - frequency noise; and high - frequency eddy - current noise at the cross - section of the exhaust valve.

2. Combustion noise

Combustion noise is the main noise source of an internal combustion engine. The periodic and sharp changes in gas pressure caused by the combustion of the combustible mixture in the cylinder subject parts such as the piston, cylinder head, cylinder block, connecting rod, piston pin, and crankshaft to impact loads, resulting in structural vibration and noise. The main factors affecting combustion noise include structural factors, operating factors, and other factors.

(1)Structural factors: The design of the combustion chamber structure and the entire combustion system has a significant impact on the pressure rise ratio, the maximum explosion pressure, and the cylinder pressure spectrum curve, thus affecting the generated noise. Generally, among direct - injection combustion chambers, the open - type combustion chamber produces the highest noise, the spherical combustion chamber has relatively lower noise, and the indirect - injection combustion chamber has the lowest noise. Combustion noise is transmitted to the outside through structural parts such as the diesel engine cylinder liner, engine block, and cylinder head. Since the rigidity of these structural parts is relatively high and their natural vibration frequencies are in the medium - and high - frequency ranges, the low - frequency components cannot be transmitted smoothly. Therefore, the main components of the combustion noise heard by human ears belong to the medium - and high - frequency ranges. Combustion noise is transmitted through the crank - connecting rod mechanism. Reducing the cylinder diameter and increasing the piston stroke, that is, using a larger S/D value while keeping the cylinder working volume unchanged, can effectively reduce the transmission of combustion noise.

(2)Operating factors: Noise changes with the rotation speed and load. Generally, the noise of direct - injection diesel generator sets increases with the increase of rotation speed and load, while that of indirect - injection diesel generators increases less.

(3)Other factors: Factors such as the injection timing of the diesel generator, fuel quality, mixture quality, and various factors affecting the pressure rise ratio all affect combustion noise.

3. Mechanical noise

Due to the periodic changes and mutual impacts of the forces between the internal components of the diesel engine, the surface vibration is caused, resulting in noise. Mechanical noise increases rapidly with the increase of rotation speed. The main components that generate mechanical noise include the piston, cylinder head, cylinder block, cylinder liner, connecting rod, piston pin, crankshaft, valve train, transmission gears, fuel injection pump, etc. The design, manufacturing quality, and material selection of these components have an important impact on noise. The structural stiffness, rotation speed, and clearance of moving parts of the diesel engine are the main factors affecting mechanical noise.

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