A centrifugal fan volute

Abstract

The invention relates to a centrifugal fan volute which comprises an air outlet and a cavity for accommodating an impeller. A volute tongue protruding toward the cavity is arranged in a position, close to the air outlet, of the inner wall of the volute. A molded line of the volute comprises a starting line AP located at one end of the molded line and corresponding to the position of the volute tongue and a finishing line HG located at the other end of the molded line. A first connecting line PD and a second connecting line DG are successively arranged between the starting line AP and the finishing line HG. The starting point P of the first connecting line PD is located on the volute tongue, the point D of the first connecting line PD is in a position of a minimum gap between the inner wallof the volute and the outer circumference of the impeller, a connecting line between the point D and the center of circle O of the impeller is OD, and the second connecting line DG is partially in mirror symmetry to the first connecting line PD relative to the connecting line OD. Therefore, the distance from the minimum gap to the volute tongue is changed. A lampblack air flow passing the volutetongue turns greatly and oil-gas separation and accumulation caused by impact of the air flow in the minimum gap are reduced, so that follow-up accumulation of oil stains on the volute tongue is further reduced.

Description

technical field [0001] The invention relates to the field of fans, in particular to a centrifugal fan volute. Background technique [0002] Household range hoods use centrifugal fans to extract oily air out of the kitchen and discharge it to the public flue or directly to the outside. Among them, centrifugal fans have been widely used in range hoods due to their advantages such as large suction, low noise, and compact structure. application. [0003] The volute is one of the core components of the centrifugal fan. Its function is to concentrate the gas leaving the impeller, export it to the outlet of the volute, and convert the dynamic pressure into static pressure. The volute of the existing centrifugal fan includes a front cover, a rear cover, and a surrounding wall connecting the front cover and the rear cover. A volute tongue is installed near the volute exit. The function of the volute tongue is to divert the gas directed to the volute exit and prevent part of the gas...

AI Technical Summary

Problems solved by technology

But in fact, due to the non-axisymmetric shape of the volute, especially the influence of the volute tongue, a non-uniform pressure field will be formed at the outlet of the impeller, which will inevitably make the flow field at the outlet of the impeller, that is, the flow field at the inlet of the volute.

[0004] The applicant has previously applied for a Chinese utility model patent "a centrifugal fan volute" with the patent number CN201720594983.5 (the authorized announcement number is CN206957987U). The volute line also includes a first helix with a constant expansion angle. CD and the second helix EM whose expansion angle tapers, the first helix CD is connected to the starting line AC, the second helix EM is connected to the end line MN, and the ring wall is in front of and behind the outer side of the fan outlet The width is greater than the front and rear width of the inner side. The design of the volute uses the front and rear dimensions of the volute to compensate for the flow loss caused by the smaller left and right dimensions of the volute. When the tongue is intercepted, it is easy to separate the oil fume, and the grease accumulates and flows to the lowest point of the snail tongue, especially when the weather is cold. After a long time of use, the oil droplets accumulate and accumulate, and after drying, it is easy to form solid droplets at the snail tongue, so that the snail tongue and The smaller the impeller gap, it is easy to cause the noise to increase significantly, and even whistling; while the ordinary shallow tongue or concave volute tongue can reduce the accumulation of grease to a certain extent, but the actual gap also increases, making the maximum static pressure and The actual flow of users has decreased

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