The noise source of micro pump and effective solution of noise reduction

With the progress of science and technology, more and more devices have been introduced into people's life and work. However, the running noise of these devices directly affects the user experience and sense of quality of products. We often encounter customers consulting low noise micro pump, especially in the medical, household appliances and other industries, low noise is an important performance requirement.

So, how can we reduce the noise of the micro dc water pump? This article will analyze noise sources and show effective methods of micropump noise reduction, giving you a more comprehensive understanding of how low noise micropumps are implemented.

1.The noise source of the micro dc water pump

Pump noise is a reflection of the characteristics of the pump working state, and mainly produced by its inner parts or the flowing medium.
From the source, noise is mainly divided into: fluid power noise, electromagnetic noise, mechanical noise, hydraulic noise.
Fluid dynamic noise: When the micro dc pump is working, it continuously generates pulses of fluid pressure, which excites the vibration of the pump body, valves, pipes and other components to radiate noise to the outside world. The test found that the larger the flow of the pump or pump motor running speed is higher, the fluid power noise will be more obvious.
Electromagnetic noise: Electromagnetic noise is mainly caused by the periodically changing radial electromagnetic force or unbalanced magnetic pulling force in the motor, which causes magnetostriction and vibration of the core and winding. Electromagnetic noise is also related to the vibration characteristics of the stator and rotor itself.

Mechanical noise: It is the main source of micro pump noise, produced by the pump internal bearing friction, gasket friction and rotor imbalance impact shaft, etc.
Hydraulic noise: It’s mainly caused by pump impeller blades, cavitation, uneven flow velocity distribution at the impeller inlet, vortex, and surge phenomena.

2.Noise control methods of micro dc water pump

In order to effectively reduce the noise during pump operation, micro quiet water pump products can adopt the following technologies and methods to reduce the noise and vibration during work:

a.Design

For pump noise, there are many related important design points: electronic control scheme, motor design, parts processing accuracy, assembly accuracy, pump head shape design, etc. Among them, the frictional sound influenced by bare pump noise, parts accuracy and the flow sound influenced by pump head design are the main source. After cooperating with the customer's products, the noise of the whole device and the design of the motor and the electric control scheme are the main ones. The following is a simple analysis of the electronic control scheme, parts accuracy, assembly accuracy.

--Electric control scheme
As there is a switching process in the commutation of the motor, each commutation will cause a vibration of the motor, which is called torque ripple. Field-oriented Control (FOC) scheme can accurately control the size and direction of the magnetic field, making the motor torque stable and improving the noise of the bare pump. At present, both FOC and non-FOC schemes of TOPSFLO can achieve high motor efficiency points in the industry, which is available for customers.

--Parts processing accuracy
All parts that produce relative motion during work will produce friction noise, such as rotor and shaft, rotor and gasket. The dynamic balance of the rotor is a very important factor affecting the noise of the motor. Because the rotor is unbalanced, periodic centrifugal force will occur during rotation, causing vibration and noise. Therefore, the accuracy of the parts must be controlled very precisely in order to effectively control the noise. TOPSFLO adopts imported high-precision ceramic shaft, magnetic quiet rotor, rotor unbalance is much lower than the market average value.

--Assembly accuracy
There are many control points in the pump assembly, such as the coaxiality of the rotor and the stator, the verticality of the shaft, and so on. These, if not well controlled, can cause the same periodic noise as a poor rotor balance. TOPSFLO adopts imported materials and high precision molds to ensure the perfect coordination between components during assembly.

b.Test
The silent room is a noise control measure that uses sound insulation to cover the noise source in a small space so that the noise is rarely transmitted. The shape of the silent room is often designed to be close to the outline of the sound source and installed as close as possible to the sound source. The sound insulation wall of the TOPSFLO silent room adopts a super energy-concentrating sound insulation wall, with a total of 20 layers and a thickness of 400mm. It has all-weather anti-interference ability against external noise and vibration, and provides the best conditions for the shock and noise reduction of the quiet water pump.

c.Installation and operation
Strictly implement the installation procedure during installation to prevent sound sources.
During installation, be sure to use the standard rubber shock-absorbing mounting feet and flexible hoses to connect the pipes, which can effectively slow down the transmission of vibration noise through the equipment chassis and gas pipelines.

In addition, it is possible to reduce mechanical noise by adding sound-insulating materials or boxes to the outside of the pump. It should be noted that some high-power micro-pumps are equipped with heat dissipation, and the heat dissipation part needs to maintain air circulation. When adding sound insulation measures, the heat dissipation part needs to be exposed to avoid overheating and shutdown of the pump.

Pay attention to exhaust (empty) in operation, ensure the allowable suction height or ensure the necessary NPSH, and control the minimum flow of the pump and the overload flow of the pump.

3.Silent micro pump recommendation

TOPSFLO silent water pump series adopts DC magnetic drive three-phase motor, patented silent suspension rotor, and comprehensively uses flow channel optimization and sealing optimization to achieve a noise value of ≤25dB (A), which is 5-10dB(A) lower than the industry average. When running, the sound made by the water pump is softer than the sound of flipping a book, and only slightly higher than the sound of falling leaves. It is very popular with customers in small household appliances, plumbing mattresses, medical beauty and other sub-sectors.

For more product details, please contact TOPSFLO pre-sales engineer to check the product manual.