Noise reduction protective screen for range hood and design method thereof

Abstract

The application discloses a noise reduction protective screen of an oil fume extractor and a design method thereof. The noise reduction protective screen of the oil fume extractor is arranged at an air inlet of an impeller. The noise reduction protective screen of the oil fume extractor comprises a protective screen body. The protective screen body is arranged between the impeller and an oil screen along an axial direction of the impeller. The protective screen body comprises a first profile and a second profile. The first profile is arranged at an edge of the protective screen body. A plurality of air inlet holes are formed in the first profile. At least one arc-shaped structure is arranged on a cross section of the first profile. The arc-shaped structure extends from the edge of the protective screen body to the axis. The second profile is arranged at the axis of the protective screen body and corresponds to an impeller nut of the oil fume extractor. A guide surface is arranged on a cross section of the second profile. The second profile is not ventilated along the axial direction of the protective screen body. The airflow is constrained by the special-shaped cross section, the airflow resistance entering the impeller is reduced, and the noise is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of range hood noise reduction protective screen and its design method. BACKGROUND

[0002] With the increasing demand of users for cooking operation space, thin design of range hood gradually becomes a new trend. With the continuous progress of fan and motor technology, the range hood industry continues to launch ultra-thin design range hood. However, due to the reduction of fan air duct in the thickness direction, the size needs to be increased in the radial direction to meet the requirements of air volume and noise control. This leads to the increase of impeller diameter and fan inlet. For side suction range hood with open inlet design, the flow rate decreases after the inlet of the whole machine is enlarged, which affects the suction and exhaust effect of oil fume. And due to the limitation of the appearance size of the whole machine (the thickness of the whole machine b ≤ 200 mm, the height of the smoke collection cavity h ≤ 420), the upper half of the fan inlet is blocked, which leads to poor inlet flow state and high working noise.

[0003] The existing range hood usually increases the fan speed to meet the air volume requirement, but the fan speed increases at the same time, which increases the energy consumption and noise. SUMMARY

[0004] The technical problem to be solved by the present application is to overcome the defects of large energy consumption, large noise and poor oil fume suction effect of the range hood in the prior art, and to provide a range hood noise reduction protective screen and its design method.

[0005] The present application solves the above technical problems by the following technical solutions:

[0006] A range hood noise reduction protective screen is provided, which corresponds to the inlet of the impeller, and comprises:

[0007] The protective screen body is arranged between the impeller and the oil screen along the axial direction of the impeller, and comprises a first profile and a second profile. The first profile is arranged at the edge of the protective screen body, and a plurality of air inlet holes are formed in the first profile. At least one arc-shaped structure is arranged on the cross section of the first profile, and the arc-shaped structure extends from the edge of the protective screen body towards the axis. The second profile is located at the axis of the protective screen body and corresponds to the impeller nut of the range hood. The second profile has a guide surface on its cross section, and the second profile is not ventilated along the axis of the protective screen body.

[0008] In the scheme, by setting the cross section of the protective net body into a first profile and a second profile, the first profile includes at least one arc structure, and the second profile has a guide surface to constrain the airflow, that is, the cross section of the protective net body is a special-shaped cross section, compared with a flat panel, the air intake into the impeller can be ensured in the limited area of the first profile, the airflow resistance into the impeller is reduced, the turbulence of the airflow is reduced, and then the noise is reduced. In addition, without increasing the impeller speed, the power consumption and use cost are reduced, the guide plate and the smoke collecting cavity do not need to be improved, the overall structure of the range hood is changed little, the existing type of range hood can be directly replaced, and the universality is higher.

[0009] Preferably, the distance between the axis of the protective net body and the impeller nut in the axial direction of the impeller is a first distance, the distance between the protective net body and the oil screen in the axial direction of the impeller is a second distance, and the first distance is A times the sum of the first distance and the second distance, wherein the value range of A is 0.6-0.75.

[0010] In the scheme, by setting the first distance and the second distance between the protective net body and the impeller nut and the oil screen, and the first distance being A times the sum of the first distance and the second distance, the airflow resistance into the impeller is reduced by the distance setting relationship, and the effect of reducing resistance and noise is improved.

[0011] Preferably, the cross section of the protective net body in the axial direction of the impeller forms a coordinate system from the axis of the protective net body in the radial direction of the protective net body and the axial direction perpendicular to the radial direction, wherein the axis extending towards the oil screen in the axial direction of the protective net body is the positive direction of the X axis, the axis extending towards the upper half region of the protective net body perpendicular to the positive direction of the X axis is the positive direction of the Y axis, and the first profile is located in the coordinate system and forms the arc structure through the connection line of the first endpoint, the second endpoint and the third endpoint.

[0012] In the scheme, by the above setting, the arc structure is simulated by the first endpoint, the second endpoint and the third endpoint in the coordinate system, the cross section of the first profile is optimized, the flow loss of the impeller inlet airflow is reduced, and the effect of reducing resistance is improved.

[0013] Preferably, the first endpoint is located at the edge of the protective net body, the X axis coordinate of the second endpoint is BH, the Y axis coordinate is CR, the X axis coordinate of the third endpoint is DH, and the Y axis coordinate is ER, wherein the value range of B is -0.02- -0.1, the value range of C is 0.8-0.9, the value range of D is -0.6- -0.75, the value range of E is 0.5-0.6, and R is the radius of the air inlet ring sleeved on the edge of the protective net body.

[0014] In this scheme, the above settings are used to optimize the first endpoint, the second endpoint, and the third endpoint within a certain range.

[0015] Preferably, the X-axis coordinate of the first endpoint is -16.5 and the Y-axis coordinate is 166, the X-axis coordinate of the second endpoint is -0.5 and the Y-axis coordinate is 145, the X-axis coordinate of the third endpoint is -15.4 and the Y-axis coordinate is 88.3, ​​and the line connecting the first endpoint, the second endpoint, the third endpoint and the axis of the protective net body forms a plane of rotation.

[0016] In this scheme, the above-mentioned settings are used to form a rotating surface, which rotates along the axis of the main body of the protective net to form the main body of the protective net.

[0017] Preferably, the connecting line is a curve.

[0018] In this scheme, the connecting lines are curves, so that the cross-section of the first surface has an arc-shaped structure. Compared with straight lines, the sequential connection of curves can increase the flow rate of the airflow entering the impeller while keeping the radius of the main body of the protective net unchanged.

[0019] Preferably, the curve is an arc, and the surface of rotation has a first arc, a second arc, a third arc, and a fourth arc. The center of the first arc has an X-axis coordinate of -26.9 and a Y-axis coordinate of 141.6. The center of the second arc has an X-axis coordinate of -15.5 and a Y-axis coordinate of 144.9. The center of the third arc has an X-axis coordinate of 84.5 and a Y-axis coordinate of 88. The center of the fourth arc has an X-axis coordinate of -15 and a Y-axis coordinate of 30.8.

[0020] In this scheme, the above settings are used to connect the first end point, the second end point, the third end point, and the axis of the main body of the protective net through the first arc, the second arc, the third arc, and the fourth arc in sequence to form the first surface and the second surface. This allows for accurate positioning of the center coordinates of the first arc, the second arc, the third arc, and the fourth arc in the coordinate system, thereby improving the accuracy of the arcs and reducing the flow loss of the impeller inlet airflow.

[0021] Preferably, the noise reduction and protection net of the range hood further includes sound-absorbing cotton, which is covered on the second profile and corresponding to the impeller nut, and the thickness of the sound-absorbing cotton is 5-8mm.

[0022] In this solution, sound-absorbing cotton is installed to further reduce the noise generated by the range hood fan during operation. At the same time, the sound-absorbing cotton is installed corresponding to the fan impeller nut to reduce the noise generated by turbulence impacting the main body of the protective net.

[0023] A design method of a noise reduction protective screen of a range hood, the design method being used for the noise reduction protective screen of the range hood as described above, and comprising the following steps:

[0024] S1. By geometric parameterization modeling, a finite element analysis software is used to simulate and calculate the internal flow field of the range hood, a coordinate system is established, and the coordinates of the first end point, the second end point and the third end point are simulated in the coordinate system.

[0025] S2. Connecting the first end point, the second end point, the third end point and the origin of the coordinate system forms a first profile and a second profile.

[0026] In this scheme, by analyzing the internal flow field of the range hood, a coordinate system is established to simulate the first profile and the second profile, so that the main body cross section of the protective screen is a special-shaped cross section, thereby realizing the reduction of the flow resistance of the impeller inlet airflow and the reduction of the noise.

[0027] Preferably, in step S1, the following is further included:

[0028] A plurality of air inlet holes are formed in the first profile, and the opening rate of the air inlet holes is 50% to 70%.

[0029] In this scheme, by the above setting, the airflow flow rate entering the impeller is ensured without increasing the impeller speed.

[0030] The positive progress effect of the present application is that: by setting the cross section of the protective screen main body into the first profile and the second profile, the first profile includes at least one arc structure, and the second profile has a guide surface to constrain the airflow, that is, the cross section of the protective screen main body is a special-shaped cross section, compared with a flat panel, the air intake amount entering the impeller can be ensured in the limited first profile, the airflow resistance entering the impeller is reduced, the airflow turbulence condition is reduced, and the noise is reduced. In addition, the impeller speed does not need to be increased, the power consumption and the use cost are reduced, the guide vane and the smoke collecting cavity do not need to be improved, the overall structure of the range hood is slightly changed, the range hood of the present application can be directly replaced on the existing type of range hood, and the universality is stronger. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a perspective view of the range hood of a preferred embodiment of the present application.

[0032] Figure 2 It is a position relationship diagram of the protective screen main body and the fan impeller of a preferred embodiment of the present application.

[0033] Figure 3 It is a position relationship diagram of the protective screen main body and the impeller nut of a preferred embodiment of the present application.

[0034] Figure 4A perspective view of a protective screen body according to a preferred embodiment of the present application.

[0035] Figure 5 A side view of a protective screen body according to a preferred embodiment of the present application.

[0036] Figure 6 A position relationship diagram of a first profile and a second profile in a coordinate system according to a preferred embodiment of the present application.

[0037] Figure 7 A position relationship diagram of an arc and an arc center in a coordinate system according to a preferred embodiment of the present application.

[0038] Explanation of reference signs:

[0039] Range hood 1000

[0040] Protective screen body 100

[0041] First profile 10

[0042] Air inlet hole 11

[0043] Arc-shaped structure 12

[0044] Second profile 20

[0045] Guide surface 21

[0046] Impeller 200

[0047] Impeller nut 201

[0048] Smoke collecting cavity 300

[0049] Deflector 400

[0050] First end point 1

[0051] Second end point 2

[0052] Third end point 3

[0053] First arc 101

[0054] Second arc 102

[0055] Third arc 103

[0056] Fourth arc 104

[0057] Sound-absorbing cotton 4 DETAILED DESCRIPTION

[0058] The present application will be further described by way of examples without limiting the present application to the examples described.

[0059] The present embodiment provides a range hood noise reduction protective screen, and the specific structure is as followsFigure 1 、 Figure 2 、 Figure 3 、 Figure 4 and Figure 5 As shown in the drawings, the range hood noise reduction protection net is arranged corresponding to the air inlet of the impeller 200, and the range hood noise reduction protection net comprises:

[0060] The protection net body 100 is arranged between the impeller 200 and an oil screen (not shown in the drawings) along the axial direction of the impeller 200, and the protection net body 100 comprises a first profile 10 and a second profile 20. The first profile 10 is arranged at the edge of the protection net body 100, a plurality of air inlet holes 11 are formed in the first profile 10, at least one arc-shaped structure 12 is arranged on the cross section of the first profile 10, the arc-shaped structure 12 extends from the edge of the protection net body 100 to the axis, the second profile 20 is located at the axis of the protection net body 100 and is arranged corresponding to the impeller nut 201 of the range hood 1000, the cross section of the second profile 20 has a guide surface 21, and the second profile 20 is not ventilated along the axial direction of the protection net body 100.

[0061] Specifically, the range hood 1000 comprises a smoke collecting cavity 300 and a guide plate 400. The guide plate 400 is hinged to the inlet of the smoke collecting cavity 300 and forms a guide area when the guide plate 400 is opened, and guides the airflow, i.e. the oil fume, into the smoke collecting cavity 300 when the fan is working. This is the prior art and will not be described in detail here. It can be understood that the impeller 200 part of the fan is arranged corresponding to the inlet of the smoke collecting cavity 300, which makes the airflow have a certain resistance when entering the smoke collecting cavity 300 and the inlet of the impeller 200, and forms a flow dead zone. The area mainly surrounds the edge of the air inlet ring 5, which is a structure that is sleeved on the outer circumferential side of the protection net body 100. On this basis, the protection net body 100 structure is improved in this embodiment. First, the cross section of the protection net body 100 along the axial direction of the impeller 200 is arranged as the first profile 10 and the second profile 20. The first profile 10 and the second profile 20 are of different cross sections. The first profile 10 has at least one arc-shaped structure 12 from the edge of the protection net body 100 to the axis, so as to increase the cross-sectional area within the limited radius of the protection net body 100 through the arc-shaped structure 12, and then improve the airflow flow rate when the airflow enters through the air inlet hole 11 to enter the inlet of the impeller 200. And the first profile 10 arranged near the flow dead zone can improve the airflow velocity, improve the aerodynamic performance, and improve the air inlet speed and uniformity of the range hood 1000 as a whole and the air inlet efficiency. According to the test results, the air inlet efficiency is improved by 1-2 points. The test results are calculated after being measured by the existing measuring instrument. This is the prior art and will not be described in detail here.

[0062] Compared with the flat plate, the first profile 10 can ensure the air intake into the impeller 200, reduce the air flow resistance into the impeller 200, and reduce the turbulence of the air flow, thereby reducing the noise. In addition, the second profile 20 is provided with a guide surface 21 on the cross section, which is arranged near the axis of the protective net body 100, so as to constrain the air flow to the axis of the protective net body 100 through the guide surface 21 and guide the air flow to the first profile 10, thereby improving the air flow efficiency on the second profile 20, improving the aerodynamic performance of the protective net body 100, enhancing the negative pressure strength of the flow field of the range hood 1000, and keeping the air intake effect of each surface, i.e. the smoke suction effect consistent.

[0063] In addition, without increasing the rotation speed of the impeller 200, the power consumption and use cost are reduced, the flow guide plate 400 and the smoke collecting cavity 300 do not need to be improved, the overall structure of the range hood 1000 is slightly changed, and the range hood 1000 of the existing model can be directly replaced, which is more universal.

[0064] Further, in the embodiment, the distance between the axis of the protective net body 100 and the impeller nut 201 in the axial direction of the impeller 200 is a first distance, the distance between the protective net body 100 and the oil screen in the axial direction of the impeller 200 is a second distance, and the first distance is A times the sum of the first distance and the second distance, wherein the value range of A is 0.6-0.75.

[0065] Specifically, the sum of the distances between the impeller nut 201, the protective net body 100 and the oil screen arranged in sequence in the axial direction of the impeller 200 is the sum of the first distance and the second distance, wherein the first distance is H1, the second distance is H2, and H1=A(H1+H2). By setting the distance relationship between the impeller nut 201, the protective net body 100 and the oil screen, the air impact flow loss between the front cover plate of the fan impeller 200 and the protective net body 100 and the oil screen is reduced, and the air impact flow loss between the protective net body 100, the oil screen and the impeller nut 201 is also reduced, thereby improving the effect of reducing resistance and noise.

[0066] According to the test results, the impact noise can be reduced by 1-2 dB. The test results are measured by the existing decibel measuring instrument, which is the prior art and will not be described in detail here.

[0067] As Figure 6 and Figure 7As shown, in the embodiment, the cross section of the protective screen body 100 along the axial direction of the impeller 200 is formed with a coordinate system along the radial direction and the axial direction perpendicular to the radial direction of the protective screen body 100 from the axis of the protective screen body 100, wherein the axis extending along the axial direction of the protective screen body 100 towards the oil screen is the X-axis positive direction, the axis perpendicular to the X-axis positive direction and extending towards the upper half region of the protective screen body 100 is the Y-axis positive direction, and the first profile 10 is located in the coordinate system and forms an arc-shaped structure 12 by connecting the first end point 1, the second end point 2 and the third end point 3.

[0068] Specifically, the axis at the protective screen body 100 is the origin of the coordinate system, i.e. the O point, the axis extending along the axial direction of the protective screen body 100 towards the oil screen is the X-axis positive direction, it can be understood that the axis extending from the O point towards the impeller nut 201 is the X-axis negative direction, the axis perpendicular to the X-axis positive direction and extending towards the upper half region of the protective screen body 100 is the Y-axis positive direction, and the axis perpendicular to the X-axis positive direction and extending towards the lower half region of the protective screen body 100 is the Y-axis negative direction, so as to form an XOY coordinate system along the cross section of the protective screen body 100 along the axial direction of the impeller 200, and by establishing the XOY coordinate system, the first profile 10 and the second profile 20 connected in sequence from the edge of the protective screen body 100 towards the axis are simulated, and for the cross section of the first profile 10, the first end point 1, the second end point 2 and the third end point 3 coordinates established in the XOY coordinate system are connected in sequence to realize, the first end point 1, the second end point 2 and the third end point 3 are connected to form a plurality of arc-shaped structures 12, so as to form the cross section of the first profile 10 by the plurality of arc-shaped structures 12, compared with the simulation mode of the plurality of end points arranged in disorder, the end point position is accurate when simulated by the XOY coordinate system, the boundary point of the first profile 10 is simpler, the time for optimizing the first profile 10 is reduced, the flow loss of the inlet gas flow of the impeller 200 is reduced, and the drag reduction effect is improved.

[0069] In the embodiment, the first end point 1 is located at the edge of the protective screen body 100, the X-axis coordinate of the second end point 2 is BH, and the Y-axis coordinate is CR, the X-axis coordinate of the third end point 3 is DH, and the Y-axis coordinate is ER, wherein the value range of B is -0.02- -0.1, the value range of C is 0.8-0.9, the value range of D is -0.6- -0.75, the value range of E is 0.5-0.6, and R is the radius of the air inlet ring 5 sleeved on the edge of the protective screen body 100.

[0070] Specifically, the coordinates of the first end point 1, the second end point 2 and the third end point 3 are simulated in the XOY coordinate system, wherein B, C, D and E are coefficients, so as to optimize the first end point 1, the second end point 2 and the third end point 3 in a certain range. The first end point 1 is the starting point of the first profile 10 because it is arranged at the edge of the protective screen body 100, and the first end point 1, the second end point 2 and the third end point 3 are sequentially connected and finally connected with the origin O of the XOY coordinate system, thereby forming the first profile 10 and the second profile 20. It can be understood that the air inlet ring 5 is sleeved on the edge of the protective screen body 100, and the air inlet ring 5 itself has a circular arc to guide the airflow in a special cross-section. The radius of the circular arc in the cross-section of the air inlet ring 5 is R, and the value of R is determined according to the model of the range hood 1000. This is a prior art and will not be described in detail here.

[0071] Further, the X-axis coordinate of the first end point 1 is -16.5, and the Y-axis coordinate is 166. The X-axis coordinate of the second end point 2 is -0.5, and the Y-axis coordinate is 145. The X-axis coordinate of the third end point 3 is -15.4, and the Y-axis coordinate is 88.3. The connection between the first end point 1, the second end point 2, the third end point 3 and the axis of the protective screen body 100 forms a rotation surface.

[0072] Specifically, according to the coordinate range of the first end point 1, the second end point 2 and the third end point 3, the finite element analysis software in the prior art is used for analysis to obtain specific coordinates. The connection between the first end point 1, the second end point 2, the third end point 3 and the axis of the protective screen body 100 forms a rotation surface connected with the first profile 10 and the second profile 20. The rotation surface is rotated along the axis of the protective screen body 100 to form the protective screen body 100.

[0073] In this embodiment, the connection is a curve. The cross-section of the first profile 10 has an arc structure 12. Compared with a straight line, the curve can improve the flow rate of the airflow into the impeller 200 when the radius of the protective screen body 100 remains unchanged.

[0074] Further, the curve is a circular arc, and the rotation surface has a first circular arc 101, a second circular arc 102, a third circular arc 103 and a fourth circular arc 104. The center of the first circular arc 101 has an X-axis coordinate of -26.9 and a Y-axis coordinate of 141.6. The center of the second circular arc 102 has an X-axis coordinate of -15.5 and a Y-axis coordinate of 144.9. The center of the third circular arc 103 has an X-axis coordinate of 84.5 and a Y-axis coordinate of 88. The center of the fourth circular arc 104 has an X-axis coordinate of -15 and a Y-axis coordinate of 30.8. The first end point, the second end point, the third end point and the axis of the protective screen body are connected by the first circular arc 101, the second circular arc 102, the third circular arc 103 and the fourth circular arc 104, so as to further improve the airflow constraint and drag reduction effect.

[0075] Specifically, the first end point 1 and the second end point 2 are connected by the first circular arc 101, the second end point 2 and the third end point 3 are connected by the second circular arc 102 and the third circular arc 103, and the third end point 3 and the axis of the protective net body 100 are connected by the fourth circular arc 104, so that the surfaces of the first profile 10 and the second profile 20 are smaller in air flow resistance. By accurately positioning the center coordinates of the first circular arc 101, the second circular arc 102, the third circular arc 103 and the fourth circular arc 104 in the XOY coordinate system, the circular arc accuracy is improved, and the flow loss of the impeller 200 inlet air flow is reduced.

[0076] It can be understood that the first circular arc 101, the second circular arc 102 and the third circular arc 103 in the embodiment are arc structures 12 in the first profile 10 after rotation, and the fourth circular arc 104 in the embodiment is a guide surface 21 after rotation.

[0077] Of course, in other embodiments, the curve can also be an elliptical line or other irregular line type, which is prior art and will not be described in detail here.

[0078] In the embodiment, the range hood noise reduction protective net further comprises sound-absorbing cotton 4, which is arranged on the second profile 20 and corresponds to the impeller nut 201. The thickness of the sound-absorbing cotton 4 is 5-8mm.

[0079] Specifically, the shape of the sound-absorbing cotton 4 is the same as that of the second profile 20, and is attached to the side of the second profile 20 facing the impeller nut 201. The material of the sound-absorbing cotton 4 can be pp / pet bi-component or polyurethane material in the prior art.

[0080] Since the impeller 200 inlet is often the area with the strongest intensity of aerodynamic noise radiation, the sound-absorbing cotton 4 is arranged on the second profile 20 and corresponds to the impeller nut 201, directly facing the impeller 200 inlet and corresponding to the impeller nut 201, so that the airflow impacting the second profile 20 from the impeller nut 201 fully contacts the sound-absorbing cotton 4, achieving the best sound absorption effect. According to the measurement by the decibel measuring instrument, the decibel noise reduction effect is 0.3-0.7dB compared with the traditional protective net.

[0081] The embodiment also provides a design method of a range hood noise reduction protective net. The design method is used for the range hood noise reduction protective net, and comprises the following steps:

[0082] S1, by geometric parameterization modeling, using finite element analysis software to simulate and calculate the flow field in the range hood 1000, establishing a coordinate system and simulating the coordinates of the first end point 1, the second end point 2 and the third end point 3 in the coordinate system;

[0083] S2, connecting the first end point 1, the second end point 2, the third end point 3 and the coordinate system origin forms the first profile 10 and the second profile 20.

[0084] It can be understood that the finite element analysis software and the geometric parameterized modeling are optimization software and optimization methods in the prior art. By modeling and analyzing the protective net body 100 in the flow field, the airflow flow dead zone and the airflow resistance distribution position of the fan impeller 200 inlet are obtained, and the XOY coordinate system is established to simulate the coordinates of the first end point 1, the second end point 2 and the third end point 3. According to the finite element analysis software, the specific numerical values of the coordinates of the first end point 1, the second end point 2 and the third end point 3 are determined. Finally, the first end point 1, the second end point 2 and the third end point 3 and the coordinate system origin are connected to form the first profile 10 and the second profile 20 to form a rotary surface. The rotary surface is rotated around the axis direction of the protective net body 100 to obtain the protective net body 100, so that the cross section of the protective net body 100 is a special-shaped cross section, thereby realizing the reduction of the airflow resistance of the impeller 200 inlet and the reduction of the noise.

[0085] Further, in step S1, the following is further included:

[0086] A plurality of air inlet holes 11 are formed in the first profile 10, and the opening rate of the air inlet hole 11 is 50% to 70%.

[0087] Specifically, the shape of the air inlet hole 11 can be a circular hole, a quadrilateral hole, a hexagonal hole, etc. The opening rate of the air inlet hole 11 on the first profile 10 is 50% to 70% to ensure the airflow flow rate entering the impeller 200, without the need to increase the rotation speed of the impeller 200. The air inlet efficiency of the fan impeller 200 is improved by 1 to 2 points, the inlet air speed and uniformity of the range hood 1000 are improved, and the negative pressure strength of the flow field and the consistency of the oil fume suction effect of each surface are enhanced.

[0088] Although the specific embodiments of the present application are described above, those skilled in the art should understand that this is only an example, and the protection scope of the present application is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present application, and these changes and modifications all fall within the protection scope of the present application.

Claims

1. A noise reduction protective screen of a range hood, the noise reduction protective screen is arranged corresponding to an air inlet of an impeller, characterized in that, The range hood noise reduction protection net comprises: The protection net body is arranged between the impeller and the oil net along the axial direction of the impeller, and comprises a first profile and a second profile. The first profile is arranged at the edge of the protection net body, and a plurality of air inlet holes are formed in the first profile. At least one arc-shaped structure is arranged on the cross section of the first profile, and the arc-shaped structure extends from the edge of the protection net body to the axis. The second profile is located at the axis of the protection net body and is arranged corresponding to the impeller nut of the range hood. The cross section of the second profile has a guide surface. The second profile is not ventilated along the axial direction of the protection net body. The distance between the axis of the protection net body and the impeller nut along the axial direction of the impeller is a first distance, and the distance between the protection net body and the oil net along the axial direction of the impeller is a second distance. The first distance is A times the sum of the first distance and the second distance, wherein the value range of A is 0.6-0.

75.

2. The noise reducing screen for an exhaust hood according to claim 1, wherein The cross section of the protection net body along the axial direction of the impeller forms a coordinate system along the radial direction and the axial direction perpendicular to the radial direction at the axis of the protection net body. The axis extending along the axial direction of the protection net body towards the oil net is the X-axis positive direction, and the axis perpendicular to the X-axis positive direction and extending towards the upper half region of the protection net body is the Y-axis positive direction. The first profile is located in the coordinate system and forms the arc-shaped structure through the connection of the first end point, the second end point and the third end point.

3. The noise reducing screen for an exhaust hood according to claim 2, wherein The first end point is located at the edge of the protection net body, the X-axis coordinate of the second end point is BH, and the Y-axis coordinate is CR. The X-axis coordinate of the third end point is DH, and the Y-axis coordinate is ER, wherein the value range of B is -0.02-0.1, the value range of C is 0.8-0.9, the value range of D is -0.6-0.75, the value range of E is 0.5-0.6, and R is the radius of the air inlet hole ring sleeved on the edge of the protection net body.

4. The noise reducing screen for an exhaust hood according to claim 3, wherein The X-axis coordinate of the first end point is -16.5, and the Y-axis coordinate is 166. The X-axis coordinate of the second end point is -0.5, and the Y-axis coordinate is 145. The X-axis coordinate of the third end point is -15.4, and the Y-axis coordinate is 88.

3. The connection line of the first end point, the second end point, the third end point and the axis of the protection net body forms a rotation surface.

5. The noise reducing screen for an exhaust hood according to claim 4, wherein The connection line is a curve.

6. The noise reducing screen for an exhaust hood according to claim 5, wherein The curve is a circular arc, and the rotation surface has a first circular arc, a second circular arc, a third circular arc and a fourth circular arc. The center of the first circular arc has an X-axis coordinate of -26.9 and a Y-axis coordinate of 141.

6. The center of the second circular arc has an X-axis coordinate of -15.5 and a Y-axis coordinate of 144.

9. The center of the third circular arc has an X-axis coordinate of 84.5 and a Y-axis coordinate of 88. The center of the fourth circular arc has an X-axis coordinate of -15 and a Y-axis coordinate of 30.

8.

7. The noise reducing screen of claim 1, wherein, The range hood noise reduction protection net further comprises sound-absorbing cotton, which is arranged on the second profile and corresponds to the impeller nut, and the thickness of the sound-absorbing cotton is 5-8 mm.

8. A design method of a noise-reducing protective screen for a range hood, the design method being used for the noise-reducing protective screen for a range hood according to any one of claims 1 to 7, characterized in that, The design method of the range hood noise reduction protection net comprises the following steps: S1, through geometric parameterization modeling, the finite element analysis software is used to simulate and calculate the internal flow field of the range hood, a coordinate system is established, and the coordinates of the first end point, the second end point and the third end point are simulated in the coordinate system; S2, connecting the first end point, the second end point, the third end point and the origin of the coordinate system to form a first profile and a second profile.

9. The method of designing a noise reducing screen for a range hood as claimed in claim 8, wherein, In step S1, it further comprises: A plurality of air inlet holes are formed in the first profile, and the opening rate of the air inlet hole is 50%-70%.

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