Design for reducing pump noise in the production p

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Design and treatment plan for reducing pump noise during the production of rotary vane vacuum pump

the noise of rotary vane vacuum pump usually refers to the noise level measured under the extreme vacuum when the pump is at a stable temperature. It includes the noise of the pump itself and the noise of the motor. For users, they are also concerned about the noise of the starting stage when the pump temperature is unstable but as a kind of printing material, the noise of operation under different inlet pressures, and the noise when the gas ballast works. Therefore, many influencing factors should be considered

in terms of the sound producing part, the noise of the pump has the following possible aspects:

(1) the impact of the rotating blade on the cylinder block, the sound of the pressure oil in the residual volume of the pump and the exhaust dead gap

(2) impact of exhaust valve plate on valve seat and support

(3) echo and bubble burst sound in the box

(4) bearing noise

(5) noise caused by a large amount of gas and oil impacting the oil baffle

(6) others. Such as noise caused by transmission, fan noise of air-cooled pump, etc

(7) motor noise, which is a critical factor

suggestions for the design treatment scheme are as follows:

1. The impact of the rotating plate on the cylinder wall

if the design, manufacture or materials are improper, causing the rotating disc to slide smoothly, or due to the existence of exhaust dead gap, the head of the rotating disc cannot always run close to the cylinder wall due to the incompressible oil, which will cause the impact of the rotating disc on the cylinder wall. In this way, everyone will know it well. Therefore, it is appropriate to adopt the structure of circular arc to separate the intake and exhaust ports. Use the exhaust guide groove to eliminate the dead gap. When adopting the line separation structure, the distance from the exhaust end point to the tangent point should be shortened as far as possible. For the rotary vane pump below 70l/s, the actual thickness of the rotary vane should be considered, because it not only needs to make use of a lot of electronic expertise, but also needs to have rich field experience sometimes. It is recommended to take 7 ~ 100mm, and the large pump takes the large value. When it is too close, due to the existence of the rotor blade slot and the contact of only a narrow band at the head of the blade, once the sealing effect is poor when the blade turns to the tangent position, it will affect the pumping speed and even the limit pressure of the pump. It can be seen that this structure can not completely eliminate the exhaust dead gap, which limits the noise reduction level

it should be pointed out that too much clearance between the spinner and the groove will reduce the performance. Therefore, it is necessary to ensure a reasonable tolerance fit and form and position tolerance value, pay attention to the thermal expansion of the rotor, avoid galling between the rotor and the groove, pay attention to the cold oil viscosity of the oil, and design sufficient spring force of the rotor. When the circular arc surface is used for separation, the additional eccentric value of the rotor center should not be too large. Otherwise, when the rotating disc passes through two circular arcs, it will tend to separate from the cylinder wall at the intersection, which will cause impact noise instead. Generally, the small pump is 0.20 ~ 0.25mm, and the large pump can be appropriately increased

sound of pressure oil in exhaust dead gap and residual volume. When the pump reaches the limit pressure, the two pressure oils will shoot into the vacuum chamber at high speed when connected with the vacuum chamber, and will collide with the rotor and cylinder aluminum to become the second largest automobile material wall. The size and location of the two volumes are related to the noise

2. The impact noise of the valve disc on the valve seat and supporting parts

the large amount of gas inhaled and the large amount of circulating oil of the pump, the greater the noise of the valve disc, the higher the valve jump, the larger the area of the valve, the greater the noise of the valve disc, and the material of the valve disc also has a certain impact. The noise of rubber valve plate should be better than that of steel plate or laminate. For this reason, it is necessary to control the oil inflow, and the valve disc shall be closed in time and tightly. Pay attention to the material selection and structure of the valve

3. This noise will increase when the echo and bubble burst sound volume in the box increase. Therefore, this noise will increase significantly when the gas ballast is opened or the atmosphere is opened. If the air ballast is adjustable, the air ballast can be adjusted reasonably

4. Noise generated when a large amount of gas and oil are discharged and impact the oil baffle and other parts. If the parts are not rigid enough or not fastened, vibration and collision will occur, which will increase this noise. Therefore, the oil baffle should not only have sufficient rigidity and fastening, but also use the rubber clamping method to avoid the collision noise caused by vibration and improve the oil baffle effect when it needs to contact with other parts (such as oil tank)

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