CN209875500U - Low noise fan and range hood - Google Patents

Abstract

The utility model discloses a low-noise fan, which comprises a volute and an air outlet. The volute includes a volute panel and a volute coaming, and the connection between the air outlet and the volute coaming forms the volute tongue structure of the volute. The volute panel adjacent to the volute tongue and the volute coaming are equipped with noise reduction areas. The noise reduction area includes a number of through holes for noise elimination. The perforation rate of the through holes on the volute is controlled at 2%‑2.5% , which is covered with sound-absorbing material close to the outside of the noise reduction area. The utility model sets the noise reduction area on the volute and determines the optimum opening ratio of the through hole, thereby significantly reducing the noise generated when the fan is running and achieving an obvious noise reduction effect. Through the cooperation between the sound-absorbing cotton fixing bracket and the motor reinforcement bracket, the structure of the volute is tightened, and the vibration of the fan is minimized. The close contact between the sound-absorbing cotton and the volute enhances the sealing of the volute and meets the noise reduction requirements. Under the premise of function, the air performance index of the range hood is also taken into account.

Description

Low noise fan and range hood

technical field

The utility model relates to the technical field of kitchen appliances, in particular to a low-noise fan and a range hood.

Background technique

At present, the range hood has become one of the essential electrical appliances in the modern family kitchen. With the development of society, people have higher and higher requirements for the experience in the cooking process. According to authoritative statistics, in addition to the air volume and smoking effect In addition, one of the important factors that greatly affect the user experience during use is noise. For range hoods, during normal operation, the main source of noise is the air duct system based on the volute and the fan. The noise generated by the air duct system mainly includes the following categories: 1. During the operation of the range hood, when the airflow flows through the inner surface of the volute, a turbulent boundary layer is formed, and the pressure pulsation of the turbulent airflow in the boundary layer acts on the volute. Noise is generated on the inner surface. Second, since the motor will vibrate during rotation, the vibration will be transmitted to the volute through the motor installation point to form resonance, which will further cause greater noise.

In addition, the applicant found through a large number of experiments that at the air outlet of the volute, especially at the volute tongue at the junction of the arc-shaped cavity and the direct-flow cavity of the air outlet, due to the sudden change of the airflow direction here, the internal The impact on the surface forms a larger range, causing the sound intensity in this area to protrude larger.

Contents of the invention

Aiming at the problems existing in the prior art, the purpose of the utility model is to provide a fan capable of noise reduction and vibration reduction, which is used to reduce the noise generated by the range hood during use.

In order to achieve the above object, the technical scheme of the utility model is as follows:

A low-noise fan, comprising a volute and an air outlet, the volute includes a volute panel and a volute coaming, the connection between the air outlet and the volute coaming forms the volute tongue structure of the volute, and the adjacent The position of the volute tongue and the coaming of the volute are provided with a noise reduction area, which includes a plurality of through holes for noise elimination. The perforation rate of the through holes on the volute is controlled at 2%-2.5%. The outside of the noise area is covered with sound-absorbing material.

Further, the volute panel includes a front panel and a rear panel which are arranged oppositely and have overlapping projections, and both the front panel and the rear panel are provided with noise reduction areas.

Further, the air inlet of the fan is opened on the front panel, the axis passing through the center of the air inlet from left to right is the x-axis, the axis passing through the center of the air inlet from bottom to top is the y-axis, and the noise reduction on the front panel The area is set within the second quadrant formed by the x-axis and the y-axis.

Further, the noise reduction area on the front panel is set within the range of 8° to 90° counterclockwise rotation of the positive semi-axis of the y-axis.

Further, the noise reduction area on the rear panel is set within the range of the second quadrant and the fourth quadrant formed by the x-axis and the y-axis.

Further, the noise reduction area on the rear panel is set within the range of 40° to 150° counterclockwise rotation of the positive semi-axis of the y-axis.

Further, the sound-absorbing material is sound-absorbing cotton, and the sound-absorbing cotton is installed on the volute through a sound-absorbing cotton fixing bracket.

Further, the sound-absorbing cotton fixing bracket is detachably connected to the volute through screws or rivets.

Further, the rear panel is provided with a motor mounting bracket for fixing the motor on the volute, and a motor reinforcement bracket is connected to the motor mounting bracket to reduce the resonance between the motor and the volute.

The utility model also provides a range hood, which includes a casing and an air suction port arranged on the casing. A low-noise fan is arranged inside the casing, and the air inlet communicates with the air suction port.

The utility model sets the noise reduction area at the position adjacent to the volute tongue of the fan volute panel and the volute coaming, so that the sound wave generated by the air flow passes through the through hole of the noise reduction area, and the air in the through hole rubs against the hole wall. , to convert a considerable part of the sound energy into heat energy, so that the energy carried by the sound wave is attenuated, and the technical effect of noise reduction is achieved. The noise reduction area is set adjacent to the volute tongue of the volute, so that the airflow flowing through the volute tongue can be buffered on the inner surface of the volute, effectively weakening the noise scattered by the airflow from the volute tongue, and the noise reduction effect is remarkable. At the same time, the noise reduction area is selectively set on the volute panel, which reduces the difficulty of processing, and the structure is more concise under the premise of satisfying the noise reduction function.

According to the main spectrum section of the noise distribution of the range hood, the utility model controls the perforation rate of the through hole on the volute to 2%-2.5%. Within the range of the perforation rate, the area with strong sound intensity can be scattered out of the volute. The noise of the range hood has been significantly weakened, the noise reduction effect is obvious, the operating environment of the range hood has been greatly improved, and a good user experience has been brought to the user.

By coating the sound-absorbing material outside the noise reduction area, on the one hand, the noise scattered inside the volute is further absorbed, and on the other hand, air leakage is avoided, achieving good sealing and use effects of the range hood.

The sound-absorbing cotton is fixed on the outer surface of the volute through the sound-absorbing cotton fixing bracket, so that the sound-absorbing cotton is more firmly attached to the volute. The sound-absorbing cotton is in close contact with the through hole of the volute, which reduces the loss of air performance indicators on the one hand, and at the same time reduces the vibration of the range hood to a certain extent, making the range hood more stable during operation.

In addition, the motor reinforcement bracket enhances the stability of the installation of the motor on the volute, suppresses the vibration of the motor, and reduces the resonance noise of the motor and the volute when the range hood is running.

The utility model provides a range hood using a low-noise fan, which effectively reduces the noise generated by the range hood during operation, improves the cooking environment in the kitchen, and brings good user experience to users.

In the utility model, the volute panel on which the motor is installed is the rear panel, and the other end face of the volute is the front panel.

Description of drawings

Fig. 1 is the structural schematic diagram of the front panel of the low-noise fan of the present invention;

Figure 2 is a schematic structural diagram of the rear panel of the low-noise fan;

Fig. 3 is a structural schematic diagram of a low-noise fan volute casing;

Figure 4 is a schematic diagram of the installation of the front panel and sound-absorbing cotton;

Figure 5 is a schematic diagram of the installation of the rear panel and sound-absorbing cotton;

Figure 6 is a schematic diagram of the installation of the volute coaming and sound-absorbing cotton;

Fig. 7 is the installation diagram of fan;

Figure 8 shows the peak value comparison of the resonant sound frequency range of the volute before and after installing the fan reinforcement bracket.

In the figure: 1 volute panel, 1-1 front panel, 1-2 rear panel, 1-21 motor mounting bracket, 1-22 mounting foot piece, 1-23 reinforcement rib, 1-3 motor reinforcement bracket, 2 volute Hoarding, 3 noise reduction area, 4 sound-absorbing cotton, 5 volute tongue, 6 motor, 7 sound-absorbing cotton fixing bracket.

Detailed ways

In order to clearly illustrate the design idea of the utility model, the utility model will be described below in conjunction with examples.

In the description of the present utility model, it should be noted that the orientations or positional relationships indicated by the terms "upper", "lower", "horizontal", "top" and "bottom" are all based on the orientations or positional relationships shown in the drawings. The positional relationship is only for the convenience of describing the present utility model and simplifying the description, but does not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present utility model. In addition, the terms "first" and "second" are used for descriptive purposes only, and should not be understood as indicating or implying relative importance.

Example 1

As shown in Figures 1 to 3, a low-noise fan in this embodiment includes a volute and an air outlet. The volute is composed of a volute panel 1 and a volute coaming 2, and the connection between the air outlet and the volute coaming is formed. The volute tongue 5, the position of the volute panel 1 adjacent to the volute tongue 5, and the volute coaming are all provided with a noise reduction area 3 to reduce the operating noise of the fan. The noise reduction area 3 includes a plurality of through holes for noise elimination. The perforation rate on the volute is controlled at 2%-2.5%.

By setting the noise reduction area composed of multiple through holes on the position of the volute panel adjacent to the volute tongue and the arc surface of the volute casing, the noise generated by the impact on the inner surface of the volute caused by the sharp change of the airflow direction passes through the micro The hole, on the one hand, effectively buffers the hard impact of the airflow on the inner surface of the volute, and on the other hand, greatly attenuates the energy carried by the sound wave of the airflow when passing through the hole, thus greatly weakening the impact caused by the turbulent boundary layer pulse. The noise generated by the inner surface of the volute.

The noise reduction area in the utility model corresponds to the sound intensity simulation result of the air duct. After a large number of sound intensity simulations, it is found that the areas with high sound intensity on the surface of the volute are mainly the curved surface of the volute coaming and the front and rear panels near the air outlet. Therefore, in order to solve the noise of the fan duct system, you should first The noise at the above three positions is processed, and the three positions are also closely related to the volute tongue.

The perforation rate of the through holes on the volute refers to the ratio of the sum of the areas of the through holes to the total area of the volute. In this embodiment, the perforation rate of the through hole in the noise reduction area is related to the noise spectrum, and the main spectrum segment of the range hood noise is within 5000 Hz. According to the relationship between the perforation rate and the absorption noise spectrum segment, when the through hole When the perforation rate on the volute is controlled at 2%-2.5%, the noise reduction area has an obvious noise reduction effect. Specifically, it is found that when the perforation rate is 2.18%, that is, the through-hole diameter is 2mm, and the hole spacing is 12mm, the noise reduction effect is optimal. Under this perforation rate, the noise reduction area has a significant attenuation effect on the noise scattered from the area with strong sound intensity of the volute, and the effect is the best.

The principle of noise reduction in the utility model is as follows:

When the sound passes through the hole in the form of sound waves, the air in the tiny holes will move under the action of the sound waves, causing friction between the air and the hole wall. Due to the friction and viscous force, a considerable part of the sound energy is converted into Heat energy, so that the energy of the sound wave is attenuated to achieve the purpose of noise reduction.

After the noise with reduced sound energy passes through the through hole, it is further absorbed by the sound-absorbing cotton wrapped outside the through hole, so as to achieve good noise reduction and airtight effects. The sound-absorbing cotton has a porous structure, and its noise reduction principle is the same as that of the noise passing through the through hole. The energy carried by the sound wave is converted into heat energy in the hole structure. After the sound energy is attenuated, the sound intensity of the noise is significantly weakened. Technical effect .

In the utility model, by setting the noise reduction area at the position of the volute tongue of the fan volute, the impact of the airflow acting on the inner surface of the volute tongue is fundamentally relieved, the energy carried by the sound wave of the airflow is converted, and the energy of the noise is converted into heat energy , so as to achieve the technical purpose of reducing noise.

Example 2

As shown in Figures 1-3, combined with Figures 4-6, the low-noise fan of this embodiment includes a volute and an air outlet, wherein the volute is composed of a volute panel 1 and a volute enclosure 2, and the volute panel 1 Including the front panel 1-1 and the rear panel 1-2, the volute coaming plate 2 installed between the front panel 1-1 and the rear panel 1-2 constitutes the shell structure of the integral volute, forming the running channel of the airflow in the fan . The connection between the air outlet and the volute coaming forms the volute tongue mechanism of the volute, and the noise reduction area 3 is set on the front panel 1-1 and the rear panel 1-2 adjacent to the volute tongue 5 and on the volute coaming 2 , The noise reduction area 3 is evenly distributed with a plurality of through holes for noise elimination, and the perforation rate of the through holes on the volute is 2.18%, and the outer side of the through holes is covered with sound-absorbing cotton for further absorbing noise. By setting the noise reduction area on the volute panel and the volute coaming, the turbulent boundary layer acts on the pulse air flow on the inner surface of the volute to pass through the micropores, and the sound wave energy carried by the air flow is effectively buffered Transformation is formed in the micropores, from kinetic energy to potential energy. Specifically, through the friction between the air in the micropores and the pore wall, as well as the friction and viscous force, the energy carried by the airflow is converted into heat energy. The energy of the sound wave is attenuated to achieve the purpose of noise reduction. The sound-absorbing cotton further covers the through hole, further absorbs the noise passing through the through hole, and avoids air leakage. On the premise of ensuring good air performance indicators, it meets the functional requirements for noise reduction.

In this embodiment, for the position of the volute tongue, especially the position where the front panel 1-1 of the volute and the rear panel 1-2 correspond to the volute tongue 5, the noise reduction area is set, which is consistent with the flow state of the airflow during the operation of the fan. corresponding. During the operation of the fan, at the volute tongue near the air outlet, the airflow in the volute changes from the surrounding direction to the straight-line throwing state, and the sudden change of the airflow direction forms a large-scale impact on the inner surface of the volute. The noise reduction area at the volute tongue can effectively buffer the impact caused by the airflow, greatly reducing the energy carried by the sound waves of the airflow, thereby effectively reducing the noise generated by the fan during operation and improving the operating environment of the range hood. According to the main frequency spectrum of range hood noise, combined with the relationship between the perforation rate of the through hole on the volute and the absorption noise spectrum, it is found that the optimum perforation rate of the through hole on the volute is 2.18%. The noise area can effectively weaken the noise scattered from the area with strong sound intensity of the volute, and the noise reduction effect is the best, bringing a good user experience to the user.

The air inlet of the fan is opened on the front panel. Taking the center of the air inlet as the reference, the axis passing through the center of the air inlet from left to right is the x-axis, and the axis passing through the center of the air inlet from bottom to top is the y-axis. The noise reduction area on the front panel is set within the second quadrant formed by the x-axis and the y-axis. Furthermore, the noise reduction area on the front panel is set within the range of 8° to 90° anticlockwise rotation of the positive semi-axis of the y-axis; The relationship between the rear panel and the front panel is relatively set, and it is an overlapping projection relationship. The noise reduction area on the rear panel is set within the overlapping range of the projection of the second quadrant and the fourth quadrant on the front panel. Further, The noise reduction area on the rear panel is set within the range of 40° to 150° anticlockwise rotation of the positive semi-axis of the y-axis. It should be pointed out that there is no continuous opening area on the rear panel. The purpose of this setting is to take care of the distribution area of strong sound waves and the two aspects of the motor installation structure, which not only ensures the reduction of the area of strong sound waves. Noise effect, but also make the motor installation more stable.

Referring to Figures 1-2, the volute panel installed on the motor 6 in this embodiment is the rear panel 1-2, and the corresponding other end surface is the front panel 1-1. From the perspective of motor installation, it is necessary to install the rear panel 1-2 2. A reinforcing rib 1-23 is provided in the noise reduction area close to the volute tongue 5 to ensure the stability of the structure and reduce the possibility of resonance as much as possible.

In this embodiment, by covering the outer surface of the noise reduction area with sound-absorbing cotton 4, the sound wave scattered from the through hole of the volute is further absorbed, so that the noise passing through the through hole is further reduced by the absorption of the sound-absorbing cotton , so as to achieve an obvious noise reduction effect. The noise reduction principle of the fan volute in this embodiment mainly includes two parts. First, through holes are provided on the volute panel and the volute coaming to reduce the noise generated by the airflow on the inner surface of the volute. When the noise passes through the hole in the form of sound waves, the air in the hole will move under the action of the sound waves and cause friction with the hole wall, so that a considerable part of the sound energy is converted into heat energy in the form of frictional heat, making the sound waves The energy carried can be attenuated to achieve the purpose of noise reduction; when the noise after the attenuation of the sound energy passes through the through hole and enters the sound-absorbing cotton, the sound-absorbing cotton also uses the form of vibration and friction of the air in the hole to generate heat under the action of sound waves, so that the sound energy is converted As heat energy, the noise energy is further attenuated, so as to achieve the technical purpose of further noise reduction. The noise reduction area cooperates with the sound-absorbing cotton to make the opening area on the volute form a covered state. Under the premise of ensuring noise reduction, the airtightness of the fan volute is improved, thereby achieving good air performance indicators.

Here it needs to be emphasized again that at the position of the volute tongue at the junction of the arc cavity of the volute and the DC cavity of the air outlet, due to the sudden change in the direction of the airflow here, a large-scale impact is formed on the inner surface of the volute, resulting in a relatively prominent sound intensity in this area. big. In the prior art, most of them only consider the way of setting through holes on the volute coaming and covering the sound-absorbing material. Although the noise is reduced to a certain extent, it does not consider the impact of the airflow turbulent boundary layer on the volute panel. The impact on the inner wall, the utility model through opening holes on the front and rear panels and covering the sound-absorbing cotton, cooperates with the noise reduction area on the volute coaming to form a three-dimensional noise reduction area distribution of the volute, and realizes the full Azimuth and more effective noise reduction effect. In addition, by selectively setting the noise reduction area on the volute panel, the processing difficulty of the equipment is reduced, and the loss of air volume caused by too many openings is avoided. The overall equipment is more concise.

The sound-absorbing cotton in the utility model is PET/PP two-component sound-absorbing cotton. The two-component sound-absorbing cotton uses PET (polyterephthalic acid) with low water absorption, anti-bacteria, degradable, light weight, and flame-retardant properties. Class) and PP (polypropylene) fibers, through melt-spinning PP, stretching it into long fibers in high-temperature and high-pressure air, so as to control the process of PP fiber crystallization and structure construction, and then cooling at a certain speed to make It crystallizes quickly, and then mixes it with hollow spiral ultrafine PET short fibers in the structure builder at an appropriate temperature, so that the inside of the sound-absorbing cotton forms a distribution of holes of different sizes, which is more conducive to the absorption of noise in the sound-absorbing cotton, so as to achieve Excellent noise reduction effect. Due to the special manufacturing process of this kind of sound-absorbing cotton, it can ensure that it can absorb noise in a wide frequency band. The optimal parameters of the sound-absorbing cotton in the utility model are: density 600g/m ² , thickness 20mm. Of course, those skilled in the art can also select the type and parameters of the sound-absorbing material according to the actual noise reduction requirements, such as glass fiber sound-absorbing cotton, sound-insulating felt, etc., which will not be repeated here.

Referring to Fig. 4-Fig. 6, the sound-absorbing cotton 4 of this embodiment is installed on the volute through the sound-absorbing cotton fixing bracket 7, the sound-absorbing cotton fixing bracket 7 is connected to the volute through screws, and the sound-absorbing cotton fixing bracket 7 is connected to the corresponding on the volute The screw holes can have a good restraint effect on the sound-absorbing cotton 4 , so that the sound-absorbing cotton 4 is tightly attached to the surface of the volute and closely contacts with the through hole on the noise reduction area 3 . This fixing method reduces the loss of air performance indicators, and also reduces the vibration of the range hood to a certain extent. The assembly is simple and the process is reliable, so that the range hood is more stable during operation.

Referring to Fig. 7, the rear panel 1-2 of the volute includes a motor mounting bracket 1-21 for fixing the motor 6 on the volute, and the motor 6 and the volute panel 1 are connected close to the motor mounting bracket 1-21 Resonant Motor Reinforcement Brackets 1-3. The motor mounting bracket 1-21 includes four mounting feet 1-22 connected to the volute rear panel 1-2. Since the structure of the mounting feet 1-22 is relatively weak, the motor 6 can easily pass through the motor during operation. The joint resonates with the volute panel 1, and the applicant has found through a large number of tests that the noise spectrum generated by the vibration at the installation foot piece 1-22 is between 200HZ-220HZ, and the resonance noise changes with the change of the motor speed. In this embodiment, a motor reinforcement bracket 1-3 is added between the rear panel 1-2 and the motor 6, and the shape of the motor reinforcement bracket 1-3 is the same as that of the motor installation bracket 1-21. The two brackets are closely fitted, and the motor 6, the motor mounting bracket 1-21 and the volute panel 1 are connected and fixed by screws and nuts, which improves the connection rigidity and enhances the stability of the installation of the motor 6 on the volute , so that the vibration of the motor is suppressed, reducing the resonance noise of the motor 6 and the volute when the range hood is running. It can be seen from Fig. 8 that when the connection rigidity at the position of the mounting feet 1-22 is enhanced, the peak noise generated by resonance at the frequency of 200HZ is significantly reduced, and the noise generated by the entire volute is effectively improved. The motor reinforcement bracket in this embodiment is installed on the contact side between the motor and the rear panel. According to the design concept of the utility model, it can also be installed on the other side of the rear panel, which can also achieve the effect of enhancing the rigidity of the mounting feet. In addition, in addition to the detachable connection of screws and nuts, the two brackets can also be fixed by welding to further reduce the vibration of the motor during operation. Of course, from the perspective of strengthening the connection rigidity, it can also be realized by directly thickening the motor installation area on the rear panel without providing a motor reinforcement bracket. The structure is simple, the installation is convenient, and the production cost of the equipment is reduced.

This embodiment also provides a range hood including the above-mentioned low-noise fan, including a casing and an air suction port arranged on the casing. The vents are connected. During the use of the range hood, the noise generated by the range hood is greatly reduced by setting the noise reduction area and sound-absorbing cotton on the volute, and improving the connection rigidity of the motor on the volute, and significantly weakening the connection between the motor and the volute. Vibration between shells.

It needs to be pointed out that 1. The utility model cooperates with the sound-absorbing cotton fixing bracket and the motor reinforcing bracket to make the structure of the volute more fastened, realize the synergistic effect of the two, and minimize the vibration generated by the fan and the volute ;2. Set the noise reduction area through the opening on the volute, and cover the sound-absorbing cotton on the outside, so that the noise on the inner wall of the volute passes through the through hole and the sound-absorbing cotton successively, ensuring the noise reduction effect; 3. The sound-absorbing cotton and the volute The close contact of the casing enhances the sealing of the volute, and also takes into account the air performance index of the range hood while satisfying the noise reduction function.

It should be noted that, in addition to covering the sound-absorbing material in the noise reduction area, in order to further avoid air leakage, all the outer surfaces of the volute can be wrapped with sound-absorbing cotton to minimize the noise; the sound-absorbing cotton fixing bracket can also use rivets or The form of welding is connected with the volute to increase the flexibility of installation; the through hole in the noise reduction area is preferably circular, and can also be hexagonal or other polygonal; in addition, in order to ensure the best 2.18% of the through hole on the volute The perforation rate, the diameter of the circular through hole in the noise reduction area can also be 1mm, and the hole spacing is 6mm.

Finally, it can be understood that the above embodiments are only exemplary embodiments adopted to illustrate the principles of the present invention, but the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the principle and essence of the present utility model, and these variations and improvements are also regarded as the protection scope of the present utility model.

Claims (10)

1. The utility model provides a low noise fan, includes spiral case and air outlet, its characterized in that, the spiral case includes spiral case panel and spiral case bounding wall, and the air outlet constitutes the spiral case tongue structure of spiral case with the junction of spiral case bounding wall, and the position and the spiral case bounding wall of neighbouring spiral case tongue on the spiral case panel all are provided with the area of making an uproar, and the area of making an uproar includes a plurality of through-holes that are used for the noise elimination, and the perforation rate control of through-hole on the spiral case is at 2% -2.5%, hugs.

2. The low noise blower of claim 1, wherein the volute panel comprises a front panel and a rear panel that are disposed opposite to each other and have overlapping projections, and the front panel and the rear panel are each provided with a noise reduction region.

3. The low noise fan according to claim 2, wherein the front panel is provided with an air inlet of the fan, an axis passing through a center of the air inlet from left to right is an x-axis, an axis passing through the center of the air inlet from bottom to top is a y-axis, and the noise reduction area on the front panel is arranged in a second quadrant range formed by the x-axis and the y-axis.

4. The low noise blower of claim 3, wherein the noise reduction region on the front panel is disposed within an interval of 8 ° to 90 ° of counterclockwise rotation of the positive y-axis half shaft.

5. The fan of claim 3, wherein the noise reduction region of the rear panel is disposed within the range of the second quadrant and the fourth quadrant of the x-axis and the y-axis.

6. The low noise blower of claim 5, wherein the noise reduction region on the rear panel is disposed within an interval of 40 ° to 150 ° of counterclockwise rotation of the positive y-axis half shaft.

7. The low noise blower of claim 1, wherein the sound-absorbing material is sound-absorbing cotton, and the sound-absorbing cotton is mounted on the scroll casing by a sound-absorbing cotton fixing bracket.

8. The low noise blower of claim 7, wherein the sound-absorbing cotton fixing bracket is detachably connected to the scroll case by a screw or a rivet.

9. The low noise blower according to claim 2, wherein a motor mounting bracket for fixing the motor to the volute is provided on the rear panel, and a motor reinforcing bracket for reducing resonance between the motor and the volute is connected to the motor mounting bracket.

10. A range hood, including the outer casing and locating the inlet scoop on the outer casing, characterized by that, there is the low-noise blower as stated in any claim 1-9 in the said outer casing, the air intake of the low-noise blower communicates with inlet scoop of the range hood.