CN209875500U - Low-noise fan and range hood - Google Patents

Abstract

The utility model discloses a low noise fan, including spiral case and air outlet, the spiral case includes spiral case panel and spiral case bounding wall, and the air outlet constitutes the spiral tongue structure of spiral case with the junction of spiral case bounding wall, all is provided with on the adjacent spiral tongue position of spiral case panel and the spiral case bounding wall and falls the region of making an uproar, falls the region of making an uproar and 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 closely the regional outside cladding of making an uproar of. The utility model discloses a set up on the spiral case and fall the region of making an uproar to confirm the best percent opening of through-hole, thereby show produced noise when reducing the fan operation, reach obvious noise reduction effect. Through inhaling cotton fixed bolster of sound and mutually supporting with the motor reinforcement support, make the self structure of spiral case more fastening, fall the fan vibration to minimumly, inhale the in close contact with of sound cotton and spiral case, strengthened the leakproofness of spiral case, also compromise range hood's air performance index under the prerequisite that satisfies the function of making an uproar of falling.

Description

Low-noise fan and range hood

Technical Field

The utility model relates to a kitchen appliance technical field especially relates to a low noise fan and range hood.

Background

At present, the range hood has become one of the electrical apparatus that modern family kitchen articles for use are indispensable, and along with the development of society, people experience the requirement of feeling more and more high to cooking in-process, according to authoritative data statistics, except amount of wind and smoking effect, the noise is exactly one of the important factor that greatly influences user's use experience in the use. For the range hood, in the normal use and operation process, the main source of noise is an air duct system mainly comprising a volute and a fan. The noise generated by the duct system is mainly classified into the following types: when the range hood runs, airflow forms a turbulent boundary layer when flowing through the inner surface of the volute, and pressure pulsation of airflow turbulence in the boundary layer acts on the inner surface of the volute to generate noise. Secondly, because the motor can produce the vibration at the rotation in-process, the vibration passes through the motor mounting point and transmits to the volute and forms resonance, further brings great noise.

In addition, the applicant finds out through a large number of experiments that at the air outlet of the volute, particularly at the volute tongue of the volute where the arc-shaped cavity and the air outlet direct-current cavity are intersected, the air flow direction suddenly changes sharply, a large range of impact is formed on the inner surface of the position, and the sound intensity of the area is greatly protruded.

Disclosure of Invention

Problem to prior art existence, the utility model aims to provide a can eliminate the noise and fall and weaken the fan of vibration for reduce the noise that range hood produced in the use.

In order to achieve the above purpose, the utility model discloses technical scheme as follows:

the utility model provides a low noise fan, includes spiral case and air outlet, 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 of through-hole on the spiral case is controlled at 2% -2.5%, hugs closely.

Furthermore, the volute panel comprises a front panel and a rear panel which are oppositely arranged and have overlapped projections, and noise reduction areas are arranged on the front panel and the rear panel.

Furthermore, the front panel is provided with an air inlet of the fan, an axis passing through the circle center of the air inlet from left to right is an x axis, an axis passing through the circle 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.

Further, the noise reduction region on the front panel is set in the interval range of 8-90 degrees of counterclockwise rotation of the positive half shaft of the y axis.

Furthermore, the noise reduction area on the rear panel is arranged in the range between a second quadrant and a fourth quadrant formed by the x axis and the y axis.

Further, the noise reduction region on the rear panel is set within an interval of 40 ° to 150 ° of counterclockwise rotation of the y-axis positive half shaft.

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 support.

Further, inhale the cotton fixed bolster of sound through screw or rivet with the spiral case can be dismantled and be connected.

Furthermore, a motor mounting bracket for fixing the motor on the volute is arranged on the rear panel, and a motor reinforcing bracket for reducing the resonance of the motor and the volute is connected to the rear panel in a manner of being close to the motor mounting bracket.

The utility model also provides a range hood, include the shell and locate the inlet scoop on the shell, be equipped with the low noise fan in the shell, the air intake with the inlet scoop intercommunication.

The utility model discloses a set up on the position of the neighbouring spiral shell tongue of fan spiral case panel and spiral case bounding wall and fall the area of making an uproar, the sound wave that makes the air current produce passes the through-hole of falling the area of making an uproar to the form of air and pore wall friction in the through-hole turns into heat energy as partly sound energy, thereby makes the energy that the sound wave carried obtain the decay, reaches the technological effect of making an uproar. The noise reduction area is arranged at the position close to the volute tongue of the volute, so that the airflow flowing through the volute tongue is buffered on the inner surface of the volute, the noise of the airflow scattered from the volute tongue of the volute is effectively weakened, and the noise reduction effect is obvious. Meanwhile, the noise reduction area is selectively arranged on the volute panel, the processing difficulty is reduced, and the structure is simpler on the premise of meeting the noise reduction function.

The utility model discloses according to range hood noise distribution's main frequency spectrum section, with the perforation rate control of through-hole on the spiral case at 2% -2.5%, in this perforation rate within range, can make the strong regional scattered noise that comes out of spiral case sound intensity obtain showing weakening, the noise reduction effect is obvious, has improved range hood's operational environment by a wide margin, brings good use for the user and experiences.

The noise-absorbing material is coated on the outer side of the noise-reducing area, so that on one hand, noise scattered out of the interior of the volute is further absorbed, on the other hand, air leakage is avoided, and good sealing and using effects of the range hood are achieved.

The sound-absorbing cotton is fixed on the outer surface of the volute through the sound-absorbing cotton fixing support, 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 part of the volute, so that on one hand, the loss of air performance indexes is reduced, and meanwhile, the vibration of the range hood during operation is reduced to a certain extent, and the range hood is more stable during operation.

In addition, the motor reinforcing support enhances the stability of the motor mounted on the volute, so that the vibration of the motor is inhibited, and the resonance noise of the motor and the volute when the range hood operates is reduced.

The utility model provides a pair of adopt range hood of low noise fan has effectively reduced the noise that range hood produced when the operation, has improved the culinary art environment in kitchen, brings good user experience for the user.

The utility model discloses in, the spiral case panel of motor installation is the rear panel, and another terminal surface of spiral case is the front panel.

Drawings

Fig. 1 is a schematic structural view of a front panel of a low noise fan according to the present invention;

FIG. 2 is a schematic structural view of a rear panel of the low noise blower;

FIG. 3 is a schematic structural view of a volute enclosure of the low-noise fan;

FIG. 4 is a schematic view of the installation of the front panel and the sound-absorbing cotton;

FIG. 5 is a schematic view of the installation of the rear panel and the sound-absorbing cotton;

FIG. 6 is a schematic view of the installation of the volute coaming and the sound-absorbing cotton;

FIG. 7 is a schematic view of the installation of a blower;

FIG. 8 is a comparison of the peak values of the resonant acoustic frequency bands of the front and rear volutes with the fan reinforcing bracket installed.

In the figure: the novel sound absorption device comprises a volute panel 1, a front panel 1-1, a rear panel 1-2, a motor mounting support 1-21, mounting foot pieces 1-22, reinforcing ribs 1-23, a motor reinforcing support 1-3, a volute coaming 2, a noise reduction area 3, sound absorption cotton 4, a volute tongue 5, a motor 6 and a sound absorption cotton fixing support 7.

Detailed Description

To clearly illustrate the design concept of the present invention, the following description is made with reference to the examples.

In the description of the present invention, it should be noted that the terms "upper", "lower", "horizontal", "top", "bottom", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

Example 1

As shown in fig. 1-3, the low-noise fan of the present embodiment includes a volute and an air outlet, the volute is composed of a volute panel 1 and a volute enclosure 2, a volute tongue 5 is formed at a connection portion of the air outlet and the volute enclosure, a noise reduction area 3 for reducing operating noise of the fan is disposed on both a position of the volute panel 1 adjacent to the volute tongue 5 and the volute enclosure, the noise reduction area 3 includes a plurality of through holes for eliminating noise, and a perforation rate of the through holes on the volute is controlled to be 2% -2.5%.

The noise reduction area formed by the through holes is arranged on the volute panel close to the volute tongue and the arc surface of the volute enclosing plate, so that noise generated by impact on the inner surface of the volute due to rapid change of the airflow direction passes through the micropores, on one hand, hard impact of the airflow on the inner surface of the volute is effectively buffered, on the other hand, energy carried by airflow sound waves is greatly attenuated when the energy passes through the through holes, and therefore the noise generated by impact of turbulent boundary layer pulses on the inner surface of the volute can be greatly weakened.

The utility model provides a noise reduction region is corresponding with the sound intensity analog result in wind channel. After a large amount of sound intensity simulations, it is found that the areas with larger sound intensity on the surface of the volute mainly include the arc-shaped surface of the volute coaming and the front and rear panels close to the air outlet, so that in order to solve the noise of the fan air duct system, the noise at the three positions should be processed, and the three positions are also closely related to the volute tongue.

The perforation rate of the through holes on the volute casing refers to the ratio of the sum of the areas of the through holes to the total area of the volute casing. In this embodiment, the perforation rate of the through holes in the noise reduction region is related to the frequency spectrum of noise, the main frequency spectrum section of the range hood noise is within 5000HZ, and according to the relationship between the perforation rate and the noise absorption frequency spectrum section, when the perforation rate of the through holes on the volute is controlled to be 2% -2.5%, the noise reduction region has an obvious noise reduction effect. It was found that the noise reduction effect is optimal when the perforation rate is 2.18%, i.e. the through hole diameter is 2mm and the hole pitch is 12 mm. Under the perforation rate, the noise reduction area has obvious weakening effect on noise scattered from the area with stronger spiral casing sound intensity, and the effect is optimal.

The utility model discloses the principle of making an uproar falls in as follows:

when sound passes through the through hole in a sound wave mode, air in the tiny hole moves under the action of the sound wave, so that friction between the air and the hole wall is caused, and a part of sound energy is converted into heat energy due to the action of friction and viscous force, so that the energy of the sound wave is attenuated, and the purpose of reducing noise is achieved.

Noise after the acoustic energy reduces is through the through-hole after, further by the cladding in the through-hole outside inhale the cotton absorption of sound to reach good noise reduction and airtight effect. The sound-absorbing cotton is internally provided with a porous structure, the noise reduction principle of the sound-absorbing cotton is the same as that of the noise passing through the through holes, the energy carried by the sound waves is converted into heat energy in the porous structure, and the sound intensity of the noise reaches the technical effect of obviously weakening after the sound energy is attenuated.

The utility model discloses in set up the area of making an uproar through the snail tongue position at the fan spiral case and fall, fundamentally has alleviated the impact that the air current acted on snail tongue internal surface, makes the energy that the air current sound wave carried obtain the conversion, makes the energy transformation of noise heat energy to reach the technical purpose who weakens the noise.

Example 2

As shown in fig. 1-3, and with reference to fig. 4-6, the low noise blower of this embodiment includes a volute and an air outlet, where the volute is composed of a volute panel 1 and a volute enclosure 2, the volute panel 1 includes a front panel 1-1 and a rear panel 1-2, and the volute enclosure 2 installed between the front panel 1-1 and the rear panel 1-2 forms a casing structure of an integral volute, so as to form an operation channel of an air flow in the blower. The connecting part of the air outlet and the volute surrounding plate forms a volute tongue mechanism of the volute, noise reduction areas 3 are arranged at the positions, adjacent to the volute tongue 5, of the front panel 1-1 and the rear panel 1-2 and on the volute surrounding plate 2, a plurality of through holes for eliminating noise are uniformly distributed in the noise reduction areas 3, the perforation rate of the through holes on the volute is 2.18%, and sound absorption cotton for further absorbing noise is coated on the outer sides close to the through holes. Specifically, through the friction between air in the micropores and the hole wall and the action of friction and viscous force, the energy carried by the air flow is converted into heat energy, so that the energy of the sound wave is attenuated, and the purpose of reducing noise is achieved. Inhale the sound cotton and further wrap-around to the through-hole, further absorb the noise that passes the through-hole, and avoid leaking out, under the prerequisite that guarantees to have good air performance index, satisfied the functional demand to making an uproar that falls.

In the embodiment, the noise reduction area is set for the volute tongue position, particularly the positions of the front panel 1-1, the rear panel 1-2 and the volute tongue 5 of the volute, and corresponds to the circulation state of the air flow in the operation process of the fan. In the operation process of the fan, at the volute tongue part close to the air outlet, the air flow is converted into a linear throwing-out state from the surrounding direction in the volute, and the sharp change of the air flow direction forms a large-range impact on the inner surface of the volute. The noise reduction area at the volute tongue part can effectively buffer impact caused by airflow, so that energy carried by airflow sound waves is greatly weakened, noise generated when the fan operates is effectively reduced, and the use environment of the range hood is improved. According to the main frequency spectrum section of the noise of the range hood, the relation between the perforation rate of the through hole on the volute and the noise absorption frequency spectrum section is found, the optimal perforation rate of the through hole on the volute is 2.18%, under the perforation rate, the noise reduction area can effectively weaken the noise scattered out from the area with stronger volute sound intensity, the noise reduction effect is best, and good use experience is brought to a user.

An air inlet of the fan is formed in the front panel, the axis which penetrates through the circle center of the air inlet from left to right is an x axis, the axis which penetrates through the circle center of the air inlet from bottom to top is a y axis, the noise reduction area on the front panel is arranged in the range of a second quadrant formed by the x axis and the y axis, and further, the noise reduction area on the front panel is arranged in the range of 8-90 degrees of anticlockwise rotation of a positive half shaft of the y axis; the rear panel and the front panel are oppositely arranged and in an overlapped projection relationship, the noise reduction area on the rear panel is arranged in an interval range overlapped with the projections of the second quadrant and the fourth quadrant on the front panel, and further, the noise reduction area on the rear panel is arranged in an interval range of 40-150 degrees of anticlockwise rotation of the positive half shaft of the y axis. Need point out and not set up coherent trompil region on the rear panel, the aim at who sets up like this has concurrently looked after the stronger distribution region of sound wave to and two aspects of motor mounting structure, has both guaranteed the stronger regional noise reduction of sound wave, also makes more firm of motor installation.

Referring to fig. 1-2, in the present embodiment, the volute panel mounted on the motor 6 is a rear panel 1-2, and the corresponding other end surface is a front panel 1-1, and from the perspective of motor mounting, it is necessary to provide reinforcing ribs 1-23 in the noise reduction area of the rear panel 1-2 near the volute tongue 5, so as to ensure structural stability and reduce the possibility of generating resonance as much as possible.

In the embodiment, the sound-absorbing cotton 4 is coated on the outer surface of the noise-reducing area, so that sound waves scattered from the through hole of the volute are further absorbed, noise passing through the through hole is further reduced by the absorption of the sound-absorbing cotton, and an obvious noise-reducing effect is achieved. The noise reduction principle of the fan volute in the embodiment mainly comprises two parts, namely, firstly, a through hole is formed in a volute panel and a volute enclosing plate to reduce noise generated by airflow on the inner surface of the volute, when the noise passes through the through hole in a sound wave mode, air in the through hole moves under the action of the sound wave and rubs with the hole wall, so that a considerable part of sound energy is converted into heat energy in a friction heat mode, the energy carried by the sound wave is attenuated, and the purpose of noise reduction is achieved; when the noise after the sound energy attenuation passes through the through hole and enters the sound-absorbing cotton, the sound-absorbing cotton is internally provided with a mode of generating heat by vibration and friction of air in the hole under the action of sound waves, so that the sound energy is converted into heat energy, the noise energy is further attenuated, and the technical purpose of further reducing the noise is achieved. The noise reduction area is matched with the sound absorption cotton, so that the perforated area on the volute forms a coating state, and on the premise of ensuring noise reduction, the airtightness of the fan volute is improved, and a good air performance index is achieved.

Here, it should be emphasized again that, at the volute tongue position at the junction of the arc-shaped chamber of the volute and the direct-flow chamber of the air outlet, the airflow direction abruptly changes here, so that a large-range impact is formed on the inner surface of the volute, and the sound intensity of the area is greatly protruded. Among the prior art, the mode that sets up through-hole and cladding sound absorbing material on the spiral case bounding wall has only been considered to the majority, though reduced the noise to a certain extent, but do not consider the impact of air current turbulent flow boundary layer on to spiral case panel inner wall, the utility model discloses a carry out trompil and cladding on the front and back panel and inhale the cotton form of sound, mutually support with the regional of making an uproar of falling on the spiral case bounding wall, constitute the three-dimensional regional distribution of making an uproar of falling of spiral case, realized omnidirectional and more effectual noise reduction effect. In addition, the noise reduction area is selectively arranged on the volute panel, the processing difficulty of the equipment is reduced, the air volume loss caused by too many holes is avoided, and the whole equipment is simpler on the premise of meeting the noise reduction function.

The utility model provides an inhale the sound cotton for PET/PP two ingredient inhales the sound cotton, two ingredients are inhaled the sound cotton and have been chooseed the water absorption rate low for use, fungi-proofing, the degradable, matter is light, PET (poly terephthalic acid) and PP (polypropylene) fibre that performance such as fire-retardant is outstanding, spout the silk through melting PP, stretch into long fibre with it in high temperature highly-compressed air, control the process that PP fibre crystallization and structure were built with this, later make its quick crystallization with certain speed cooling, then carry out the hybrid forming with the superfine PET short-staple of cavity spiral at the structure builder under appropriate temperature, make the inside hole that constitutes not of sound cotton size and distribute, be favorable to the noise to absorb in the sound cotton more, thereby reach excellent noise reduction. Due to the special manufacturing process of the sound-absorbing cotton, the sound-absorbing cotton can absorb noise in a wide frequency band. The utility model discloses well inhale cotton optimal parameter of sound does: density 600g/m²And the thickness is 20 mm. Of course, the kind and parameters of the sound-absorbing material, such as the sound-absorbing cotton made of glass fiber, the sound-insulating felt, etc., can be selected by those skilled in the art according to the actual noise reduction requirements, and will not be described herein.

Referring to fig. 4-6, the sound-absorbing cotton 4 of the present embodiment is installed on the spiral case by the sound-absorbing cotton fixing bracket 7, the sound-absorbing cotton fixing bracket 7 is connected with the spiral case by screws, and the sound-absorbing cotton 4 can be well constrained by the corresponding screw holes on the sound-absorbing cotton fixing bracket 7 and the spiral case, so that the sound-absorbing cotton 4 is tightly attached to the surface of the spiral case and is in close contact with the through holes on the noise reduction area 3. The fixing mode reduces the loss of air performance indexes, simultaneously reduces the vibration of the range hood during working to a certain extent, has simple assembly and reliable process, and ensures that the range hood is more stable during operation.

Referring to fig. 7, the rear panel 1-2 of the volute comprises motor mounting brackets 1-21 for fixing the motor 6 on the volute, and motor reinforcing brackets 1-3 for reducing the resonance of the motor 6 and the volute panel 1 are connected to the motor mounting brackets 1-21 in a manner of being close to the motor mounting brackets. The motor mounting bracket 1-21 comprises four mounting leg pieces 1-22 connected with the volute casing rear panel 1-2, and the mounting leg pieces 1-22 are weak in position structures, so that the motor 6 can easily resonate with the volute casing panel 1 through the connection part in the operation process, and the applicant finds through a large number of tests that the noise frequency spectrum generated by vibration at the mounting leg pieces 1-22 is between 200HZ and 220HZ, and the resonant noise changes along with the change of the rotating speed of the motor. In the embodiment, a motor reinforcing bracket 1-3 is additionally arranged between the rear panel 1-2 and the motor 6, and the shape of the motor reinforcing bracket 1-3 is the same as that of the motor mounting bracket 1-21. The two supports are tightly attached, and the motor 6, the motor mounting supports 1-21 and the volute panel 1 are connected and fixedly mounted through the screws and the nuts, so that the connection rigidity is improved, the mounting stability of the motor 6 on the volute is enhanced, the vibration of the motor is inhibited, and the resonance noise of the motor 6 and the volute when the range hood operates is reduced. As can be seen from fig. 8, after the connection rigidity at the positions of the mounting leg pieces 1-22 is enhanced, the noise peak value caused by resonance at the frequency of 200HZ is obviously reduced, and the noise generated by the whole volute is effectively improved. The motor in this embodiment consolidates the support and installs the contact side at motor and rear panel, according to the utility model discloses a design idea, can also install the another side at the rear panel, also can reach the effect of reinforcing installation foot piece rigidity equally. In addition, the detachable connection mode of the screw and the nut is adopted, and the two brackets can be fixed in a welding mode, so that the vibration of the motor during operation is further reduced. Certainly, from the angle of reinforcing connection rigidity, also can adopt not to establish motor and consolidate the support, directly realize the mode that motor installation region carries out thickening on the rear panel, simple structure, simple to operate reduces the cost of manufacture of equipment.

The embodiment also provides a range hood comprising the low-noise fan, which comprises a shell and an exhaust inlet arranged on the shell, wherein the low-noise fan is arranged inside the shell, and the air inlet of the low-noise fan is communicated with the exhaust inlet of the range hood. In the use process of the range hood, the noise reduction area and the sound absorption cotton are arranged on the volute, the connection rigidity of the motor on the volute is improved, the noise generated by the range hood is greatly reduced, and the vibration between the motor and the volute is obviously weakened.

It is important to point out that 1, the utility model makes the self structure of the volute more tight through the mutual matching of the sound-absorbing cotton fixing bracket and the motor reinforcing bracket, realizes the synergistic effect of the two, and makes the vibration generated by the fan and the volute reduced to the minimum; 2. a noise reduction area is arranged on the volute through the opening, and the outer side of the volute is coated with sound absorption cotton, so that noise on the inner wall of the volute sequentially passes through the through holes and the sound absorption cotton, and the noise reduction effect is guaranteed; 3. the sound-absorbing cotton is in close contact with the volute, so that the sealing performance of the volute is enhanced, and the air performance index of the range hood is considered on the premise of meeting the noise reduction function.

It should be noted that, except for covering the noise reduction region with the sound-absorbing material, in order to further avoid air leakage, all the outer surfaces of the volute can be covered with the sound-absorbing cotton, so that the noise is reduced to the minimum; the sound-absorbing cotton fixing bracket can also be connected with the volute in a rivet or welding mode, so that the mounting flexibility is improved; the through holes in the noise reduction area are preferably circular and can also be hexagonal or other polygons; in addition, in order to ensure the optimal perforation rate of the through holes on the volute of 2.18 percent, the diameter of the circular through holes arranged in the noise reduction area can be 1mm, and the hole distance is 6 mm.

Finally, it is to be understood that the above embodiments are merely exemplary embodiments that have been employed to illustrate the principles of the present invention, and that the present invention is not limited thereto. It will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention, and these changes and modifications are to be considered as the protection scope of the invention.

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.