Draught fan noise reduction worm tongue

Abstract

The invention discloses a draught fan noise reduction worm tongue. The draught fan noise reduction worm tongue comprises a worm tongue body and is characterized in that the upper side face and the lower side face of the worm tongue body are each provided with a noise reduction cavity, an outer cover matched with the worm tongue body is arranged outside the worm tongue body, and noise reduction holes in one-to-one correspondence to the noise reduction cavities are formed in the outer cover. Compared with the prior art, the draught fan noise reduction worm tongue has the beneficial effects thatthe noise reduction cavities are formed in the upper side face and the lower side face of the worm tongue body, the noise reduction holes in one-to-one correspondence to the noise reduction cavities are formed in the outer cover of the worm tongue body, each noise reduction cavity is matched with the corresponding noise reduction hole to form an independent noise reduction cavity, the worm tonguecan be subject to noise reduction through the Helmholtz resonant silencing principle, the structure is simple, and the noise reduction and silencing effects are better.

Description

technical field [0001] The invention relates to a range hood, in particular to a fan noise reduction volute tongue. Background technique [0002] The main function of the volute tongue of the fan used in the range hood is to intercept the flow (to prevent the impeller from idling and not to go out). Generally speaking, the volute tongue can be divided into sharp tongue, deep tongue, short tongue and flat tongue. For the traditional straight volute Tongue, the deeper the volute tongue, the smaller the gap between it and the impeller, the efficiency is improved, but the noise is increased. The distribution of the flow velocity of the airflow in the volute along the axial direction is basically a quadratic curve distribution with a high velocity in the middle and a small flow velocity at both ends. From the results of fluid simulation analysis, it can be seen that the velocity near the fan outlet is large and the velocity at both ends is small. , so there is an obvious seconda...

AI Technical Summary

Problems solved by technology

[0003] In order to reduce the noise of the fan and eliminate the vortex, people have improved the structure of the volute tongue, as disclosed in the Chinese invention patent application with the application number 201110427490. The range hood of the fan" forms a concave part on the volute tongue part of the scroll case to the outside of the scroll case, so that the concave part is arc-shaped from the direction of the air outlet. The air flow is rectified to reduce the noise generated at the volute tongue when the range hood is working, but the gap between the lower end surface of the volute tongue and the impeller is the same, so the fan is easy to generate vortices on the front and rear sides of the volute tongue when it is working

Another example is the "range hood and its volute case and volute tongue" disclosed in the Chinese invention patent application whose application number is 201210210890.X (application publication number is 103512064A). Make the airflow at the volute tongue more smooth, which in turn helps to reduce noise. Although the improved volute tongue is conducive to reducing noise due to the local deceleration of the airflow in the middle of the volute tongue, but because the upper connecting surface of the volute tongue is a plane, The front and rear airflows on both sides of the volute go out normally, but because the middle airflow velocity is high, the middle airflow and the front and rear airflows hit the connecting surface almost at the same time, resulting in increased noise superposition

The volute tongue structure disclosed above mainly reduces noise by changing the profile structure of the air inlet side of the volute tongue. Although it also has a good noise reduction effect, it is not easy to process the volute tongue, which increases the manufacturing cost of the volute tongue.

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