Centrifugal fan for oil and smoke exhaust machine and method for manufacturing volute profile line thereof

Abstract

The invention relates to a centrfugal fan for an oil and smoke exhaust machine and a method for manufacturing a volute profile line thereof. The centrfugal fan comprises a volute, a blade wheel, an air inlet ring and a motor, wherein the volute is provided with an air inlet and an air outlet; the blade wheel is arranged in the volute; the air inlet ring is arranged on the air inlet; the motor drives the blade wheel to rotate; the volute comprises a volute top plate, a volute enclosing plate and a volute base plate; and the volute enclosing plate is connected between the volute top plate and the volute base plate. The centrfugal fan is characterized in that the outline of the inner side face of the volute enclosing plate is the volute profile line, and the volute profile line is formed by the smooth transitional connection of a first straight line DE, a first arc line EF, a second arc line FG, a spiral line GH and a second straight line HI. According to the invention, after considering problems in the prior art and aiming at the characteristics of large impellor size and small volute size of the centrifugal fan for the oil and smoke exhaust machine, a design method of the volute profile line of the centrifugal fan is presented, thereby making great contribution to improving the air rate, air pressure and efficiency of the centrifugal fan for the oil and smoke exhaust machine and reducing the pneumatic noises.

Description

technical field [0001] The invention relates to a centrifugal fan used for a range hood and a method for generating a volute profile thereof. Background technique [0002] Existing centrifugal fans have been widely used in range hoods due to their advantages of large suction, low noise, and compact structure. The volute is one of the core components of the centrifugal fan. Its function is to concentrate the gas leaving the impeller, guide it to the outlet of the volute, and convert part of the dynamic pressure of the gas into static pressure. The volute shape of the centrifugal fan determines the shape of the volute, which has a great influence on the air volume, wind pressure, efficiency and aerodynamic noise of the centrifugal fan. The production method of conventional centrifugal fan volute is as follows: Figure 5 As shown, the volute profile is formed by the first straight line D 1 E. 1 , Arc E 1 f 1 , logarithmic spiral F 1 G 1 and the second straight line G 1 ...

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Problems solved by technology

[0003] like Figure 5 As shown, the logarithmic helix J in the volute type line 1 f 1 G 1 The equation of the volute is based on "the flow of wind flowing through different sections of the volute is proportional to the angle formed between the section and the initial section of the volute (ie In the formula, Q φ is the flow of any cross-section, Q is the flow of the end cross-section)", but it is actually derived from the assumption that a part of the impeller outlet near the exit of the volute (such as Figure 5 Shaded area) does not go around the logarithmic helix J 1 f 1 G 1 rotating flow, but directly from the volute outlet D 1 h 1 Outflow, therefore, the volute shape line designed by this method will cause the airflow at the exit of the impeller to be very uneven, and the velocity near the exit of the volute (shaded part) is very high, and the unevenness of the airflow at the exit of the impeller will further develop after the airflow enters the volute Deterioration, resulting in vortex in the volute, greatly reducing the air volume, wind pressure and efficiency of the fan, and the large pressure gradient in the volute will also increase the vortex noise

[0004] In addition, the distance t between the volute tongue and the impeller of the volute profile designed by conventional methods will be very small, which will increase the rotational noise

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