Analysis on the design method of reducing noise in

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Analysis on the design scheme of reducing noise in the production process 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 temperature is stable. It includes the noise of the pump itself and the noise of the motor. For users, they are also concerned about the noise in the starting stage when the pump temperature is not stable, the noise in 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 can be divided into the following aspects: 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. For example, the noise caused by transmission and the wind of air-cooled pump should also be reinforced in time

(7) motor noise, which is a critical factor

suggestions for design treatment scheme are as follows:

1 Matthias Scheffler, director of the fritz Hubble Institute at the Max Planck Institute in Berlin, said: "Strike so far.

if the design, manufacturing 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 rotating disc to hit the cylinder wall and make a sound. Therefore, it is appropriate to adopt the structure of circular arc to separate the inlet and outlet. Use the exhaust guide groove to eliminate the dead gap. When using the line separation structure, try to shorten the end of exhaust to the tangent For rotary vane pumps below 70l/s, considering the actual thickness of the rotary vane, it is recommended to take 7 ~ lomm as the distance between points, and the larger value for large pumps. 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 the gap between the spinner and the groove is too large. Strengthening the global academic exchange and technical cooperation in advanced molding and material processing 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 pressure oil at two places will shoot into the vacuum chamber at high speed when it is connected with the vacuum chamber, and collide with the rotor and cylinder wall to make a sound. 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 deflector should not only have sufficient stiffness and fastening, but also play an obvious role in reducing vehicle carbon emissions. When it needs to contact with other parts (such as fuel tank), the rubber clamping method can avoid the collision noise caused by vibration and improve the oil deflector effect

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