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2020

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08

Do you know the noise sources of micro diaphragm pumps?

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    The micro diaphragm pump is typical among micro pumps. It uses the reciprocating motion of the membrane driven by the motor to generate vacuum, inhale and press the fluid, completely isolate the motion mechanism and transport media, and the media is free of pollution. Stationary sealing without leakage; Good stability. Small size and light weight; Not afraid of idling. No lubrication and maintenance, low noise

    The micro diaphragm vacuum pump does not need a pump when pumping water. It immediately absorbs water, pumps water, and is not afraid of dry rotation when there is no water. Many advantages of micro diaphragm pump make it widely used in the instrument industry.

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    From the source, the noise of the micro diaphragm pump is mainly divided into three parts: hydrodynamic noise, mechanical noise of mechanical moving parts and motor noise.

   Hydrodynamic noise refers to the noise generated by the vibration of pump, valve, pipe and other parts when the micro pump continuously generates the pulse of fluid pressure during operation. When aspirating, the air inlet valve opens, the exhaust valve closes, and the air enters the pump chamber. Severe pressure fluctuations occur at the air inlet and inside the valve. The pressure wave of the gas is released from the air inlet through sound waves, forming intake noise. The hydrodynamic noise is determined by the working principle of the vacuum pump. Improving the pump design can reduce the noise, but this active noise reduction effect is far from meeting people's expectations.

   Mechanical noise is not the main source of micro pump noise, but the vibration of pump inner membrane, bearing friction, eccentric movement of crankshaft and connecting rod, impact of check valve, etc. These noises have randomness and represent broadband characteristics. In terms of active noise reduction, it is necessary to improve material selection, design, assembly and processing accuracy, balance, etc.

   The electromagnetic noise is mainly caused by the magnetostriction and vibration of the iron core caused by the periodically changing radial electromagnetic force or unbalanced magnetic tension of the motor. The electromagnetic noise is also related to the vibration characteristics of the stator and rotor itself. When the impact force and natural frequency resonate, even if the electromagnetic force is large or small, it will also produce a lot of noise. In order to reduce electromagnetic noise, sinusoidal windings should be used as far as possible to reduce harmonic components, and appropriate air gap magnetic density should be selected.

   Machine noise is the most important part of motor noise, such as bearing noise, rotor imbalance, installation eccentricity, etc. Carbon brushes also vibrate and make noise. In order to reduce mechanical noise, sealed bearings are generally used to prevent impurities from entering. The processing of bearing balls, inner rings and outer rings must meet the design requirements and have strict demagnetization cleaning procedures.

 

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