Volute, centrifugal fan and range hood

Abstract

The utility model provides a volute, a centrifugal fan and a range hood, the volute comprises an annular wall, an upper cover plate and a lower cover plate, and the upper cover plate is connected with the lower cover plate through the annular wall; the upper cover plate is positioned in a diffusion section area of the outlet of the volute and is bent towards the inner side of the volute; and / or, the lower cover plate is positioned in the diffusion section area of the outlet of the volute and is bent towards the inner side of the volute; the diffusion section area, located at the outlet of the volute, of the upper cover plate and / or the lower cover plate is bent towards the inner side of the volute to form an approximately trapezoidal section, so that the flowing state of airflow in the outlet area of the volute is improved, and eddy current loss is reduced.

Description

Technical Field

[0001] The utility model relates to the field of centrifugal fans, in particular to a volute, a centrifugal fan and a range hood. Background Art

[0002] The volute is one of the core components of a centrifugal fan, and the three-dimensional flow inside it is relatively complex and accompanied by vortices. The external characteristic laws of centrifugal fans with different volumes are different. As the opening degree of the volute increases, the highest efficiency point of the fan operation will migrate from small flow to large flow. At present, the national standard of range hoods "GB / T 17713-2022" includes the maximum air volume condition and the working air volume condition, corresponding to the large flow and small flow conditions of the fan respectively. Generally, it is considered that small-volume centrifugal fans have relatively small volute opening degrees, and have higher efficiency and lower noise under the working air volume condition, while large-volume centrifugal fans have larger opening degrees and have higher efficiency and lower noise under the maximum air volume condition. How to better balance the performance of the fan under the two conditions is one of the important problems in the design of multi-wing centrifugal fans for range hoods at present.

[0003] According to the flow characteristics of the rotary surface of the centrifugal fan: the rotation of the impeller makes the gas obtain kinetic energy, and the air flow in the volute accelerates circumferentially. As Figure 1 shown, under the maximum air volume condition, due to the relatively small resistance of the fan pipe network, the air flow will continue to accelerate and reach the maximum upstream of the volute tongue, resulting in an increase in the dynamic pressure at the volute outlet. Under the working air volume condition, as Figure 2 shown, due to the relatively large resistance of the pipe network, the air flow begins to decelerate near the maximum opening degree of the volute, resulting in an increase in the static pressure at the volute outlet.

[0004] Therefore, the flow field distribution in the diffuser section at the volute outlet is different due to the different pipe network resistances, resulting in differences in the internal flow fields of the fan under the two conditions. In addition, according to the flow characteristics of the meridian plane of the centrifugal fan: the air flow at the impeller outlet impacts the volute ring wall, forming vortex pairs with opposite directions and alternating intensities on the volute cross-section, which will cause eddy current losses. Figure 3 Fig. is the flow field distribution diagram of the diffuser section at the volute outlet of the prototype under the maximum air volume condition; Figure 4 Fig. is the flow field distribution diagram of the diffuser section at the volute outlet of the prototype under the working air volume condition.

[0005] In the prior art, the maximum air volume condition and at least one intermediate working point are selected on the centrifugal fan curve as independent design conditions. On the basis of the selected impeller size, a new volute profile is designed by weighted superposition according to the importance degree and the occurrence probability of each condition.

[0006] The prior art has proposed a volute profile design method with a wider efficient operating range and better performance under user conditions from the design level of the volute profile. However, in actual design, due to the limitation of the fan frame size, the upper limit of the opening adjustment of the volute profile is restricted, which affects the improvement of the fan performance. On the other hand, the prior art pays relatively little attention to the internal flow field of the fan and does not involve structural improvements in terms of optimizing the flow field details. Especially in the two operating conditions of the range hood, due to the different sizes of the pipe network resistance, there are differences in the internal flow field of the fan. Especially in the diffuser section area at the volute outlet, under the maximum air volume condition, due to the small pipe network resistance of the fan, the air flow continues to flow and reaches the maximum upstream of the volute tongue, resulting in an increase in the dynamic pressure at the volute outlet; while under the operating air volume condition, due to the large pipe network resistance, the air flow starts to decelerate and flow near the maximum opening of the volute, resulting in an increase in the static pressure at the volute outlet.

[0007] The conventional volute profile design is based on the "equal circulation method". According to the requirements of air volume, pressure, rotational speed, etc. under the preset operating conditions, the structural parameters of the fan are calculated, and its cross-section is generally rectangular. When the opening or flow area of the volute is designed unreasonably, it will cause a significant increase in the steady flow here, affecting the fan performance. For the characteristics of the vortex flow field, the most ideal cross-section of the volute is circular, and its air outlet efficiency is the highest. However, if the cross-section is designed as circular, the impeller diameter will limit the height of the impeller when it reaches a certain size. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the defects of the low air outlet efficiency and unsatisfactory flow characteristics of the volute with a rectangular cross-section in the prior art, and provide a volute, a centrifugal fan, and a range hood.

[0009] The present invention solves the above technical problems through the following technical solutions:

[0010] In the first aspect, a volute of a centrifugal fan is provided, and the volute includes an annular wall, an upper cover plate, and a lower cover plate, and the upper cover plate is connected to the lower cover plate through the annular wall;

[0011] The upper cover plate is bent inward toward the volute in the diffuser section area at the volute outlet; and / or,

[0012] The lower cover plate is bent inward toward the volute in the diffuser section area at the volute outlet.

[0013] Optionally, taking the center of the impeller of the centrifugal fan as the coordinate origin, a plane rectangular coordinate system is established;

[0014] The upper cover plate is bent at an angle of a first bending angle toward the inner side of the volute within the diffuser section area at the outlet of the volute, bounded by a first broken line; wherein, when the first broken line is perpendicularly projected onto the plane rectangular coordinate system, the perpendicular projection of one end point of the first broken line is located in the second quadrant of the plane rectangular coordinate system, and the perpendicular projection of the other end point of the first broken line is located at the intersection of the volute profile line and the negative half-axis of the horizontal axis; the first bending angle is the included angle between the intersection line of the plane where the first bending part is located and the plane where the outlet end of the volute is located and the plane where the first cover plate is located, the first bending part is the part of the upper cover plate bent toward the inner side of the volute bounded by the first broken line, and the first cover plate is the part of the upper cover plate that is not bent; and / or,

[0015] The lower cover plate is bent at an angle of a second bending angle toward the inner side of the volute within the diffuser section area at the outlet of the volute, bounded by a second broken line; wherein, when the second broken line is perpendicularly projected onto the plane rectangular coordinate system, the perpendicular projection of one end point of the second broken line is located in the second quadrant of the plane rectangular coordinate system, and the perpendicular projection of the other end point of the second broken line is located at the intersection of the volute profile line and the negative half-axis of the horizontal axis; the second bending angle is the included angle between the intersection line of the plane where the second bending part is located and the plane where the outlet end of the volute is located and the plane where the second cover plate is located, the second bending part is the part of the lower cover plate bent toward the inner side of the volute bounded by the second broken line, and the second cover plate is the part of the lower cover plate that is not bent.

[0016] Optionally, the radius of the fillet of the first bending part is less than or equal to the width of the first gap; wherein, the first gap is the axial gap between the first cover plate and the upper end ring of the impeller of the centrifugal fan.

[0017] Optionally, the radius of the fillet of the second bending part is less than or equal to the width of the second gap; wherein, the second gap is the axial gap between the second cover plate and the lower end ring of the impeller.

[0018] Optionally, the angle of the first bending angle is less than or equal to the first angle; wherein, the first angle is the angle at which the bending position of the first bending part is located in the plane of the upper disc of the impeller.

[0019] Optionally, the angle of the second bending angle is less than or equal to the second angle; wherein, the second angle is twice the first angle.

[0020] Optionally, the angle of the first bending angle is equal to the first angle, and the second bending angle is twice the first bending angle.

[0021] In a second aspect, a centrifugal fan is provided, and the centrifugal fan includes the volute as described in the first aspect.

[0022] Optionally, the centrifugal fan includes an air outlet hood, the inlet end of the air outlet hood is connected to the outlet end of the volute, and the inlet cross-section of the air outlet hood matches the outlet cross-section of the volute.

[0023] In a third aspect, an oil fume extractor is provided, and the oil fume extractor includes the centrifugal fan as described in the second aspect.

[0024] On the basis of conforming to the common knowledge in the art, the above preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0025] The positive and progressive effects of the present invention are as follows: by bending the upper cover plate and / or the lower cover plate inwardly toward the volute in the diffuser section area of the volute outlet to form an approximately trapezoidal cross-section, the flow state of the air flow in the volute outlet area is improved, and the eddy current loss is reduced. Description of the Drawings

[0026] Figure 1 It is the airflow diagram in the volute of the prototype under the maximum air volume condition;

[0027] Figure 2 It is the airflow diagram in the volute of the prototype under the working air volume condition;

[0028] Figure 3 It is the flow field distribution diagram of the diffuser section at the volute outlet of the prototype under the maximum air volume condition;

[0029] Figure 4 It is the flow field distribution diagram of the diffuser section at the volute outlet of the prototype under the working air volume condition;

[0030] Figure 5 It is the structural schematic diagram of the volute of a centrifugal fan provided in Embodiment 1 of the present invention;

[0031] Figure 6 It is the cross-sectional view of the volute of a centrifugal fan provided in Embodiment 1 of the present invention;

[0032] Figure 7 It is another plane rectangular coordinate system provided in Embodiment 1 of the present invention;

[0033] Figure 8 It is the top view of the volute of a centrifugal fan provided in Embodiment 1 of the present invention;

[0034] Figure 9 It is the top view of the volute of a centrifugal fan provided in Embodiment 1 of the present invention;

[0035] Figure 10 It is the main effect diagram of the average air volume corresponding to different first bending angles α and second bending angles β of the volute of a centrifugal fan provided in Embodiment 1 of the present invention under the working air volume condition;

[0036] Figure 11 The main effect diagram of the average total pressure efficiency corresponding to different first bending angles α and second bending angles β of the volute of a centrifugal fan provided in Embodiment 1 of the present utility model under the working air volume condition;

[0037] Figure 12 The main effect diagram of the average air volume corresponding to different first bending angles α and second bending angles β of the volute of a centrifugal fan provided in Embodiment 1 of the present utility model under the maximum air volume condition;

[0038] Figure 13 The main effect diagram of the average total pressure efficiency corresponding to different first bending angles α and second bending angles β of the volute of a centrifugal fan provided in Embodiment 1 of the present utility model under the maximum air volume condition;

[0039] Figure 14 The structural schematic diagram of a centrifugal fan provided in Embodiment 2 of the present utility model. Specific embodiments

[0040] The present utility model will be further described below by way of embodiments, but the present utility model is not limited to the scope of the described embodiments.

[0041] In the embodiments of the present utility model, prefix words such as "first" and "second" are only used to distinguish different described objects, and have no limiting effect on the position, order, priority, quantity or content of the described objects. The use of ordinal numbers and other prefix words for distinguishing described objects in the embodiments of the present utility model does not constitute a limitation on the described objects. The statements of the described objects refer to the description in the claims or the context of the embodiments, and should not constitute an unnecessary limitation due to the use of such prefix words. In addition, in the description of this embodiment, unless otherwise specified, the meaning of "a plurality" is two or more.

[0042] The total pressure efficiency in the present utility model reflects the conversion efficiency of the range hood for air volume and air pressure under the specified air volume. Specifically, the total pressure efficiency refers to the ratio of the total pressure value at the standard state of air under the specified air volume (usually 7m 3 / min) and this air volume to the input power of the main motor. The larger this ratio, the higher the conversion efficiency of the centrifugal fan for air volume and air pressure, that is, the better the performance of the range hood.

[0043] Embodiment 1

[0044] Figure 5 The structural schematic diagram of the volute of a centrifugal fan provided for this embodiment, the volute includes an annular wall 101, an upper cover plate 102 and a lower cover plate 103, and the upper cover plate 102 is connected to the lower cover plate 103 through the annular wall 101.

[0045] In an alternative embodiment, the upper cover plate is bent inward toward the volute at the diffuser section area of the volute outlet.

[0046] In an alternative embodiment, the lower cover plate is bent inward toward the volute at the diffuser section area of the volute outlet.

[0047] In an alternative embodiment, both the upper cover plate and the lower cover plate are bent inward toward the volute at the diffuser section area of the volute outlet.

[0048] In this embodiment, due to the axial dynamic and static interference clearance between the volute and the impeller, the circumferential vortex pair flow will cause leakage loss here; especially under the working air volume condition, due to the increase in pressure inside the volute, the leakage loss increases. In view of the above vortex pair flow loss and dynamic and static interference clearance, the upper cover plate and / or the lower cover plate are bent inward toward the volute at the diffuser section area of the volute outlet to form an approximately trapezoidal cross-section, improving the flow state of the air flow in the volute outlet area and reducing the eddy current loss.

[0049] In an alternative embodiment, a plane rectangular coordinate system is established with the center of the impeller of the centrifugal fan as the coordinate origin.

[0050] The upper cover plate is bent inward toward the volute at the diffuser section area of the volute outlet by an angle of the first bending angle with the first broken line as the boundary; wherein, the first broken line is vertically projected onto the plane rectangular coordinate system, the vertical projection of one end point of the first broken line is located in the second quadrant of the plane rectangular coordinate system, and the vertical projection of the other end point of the first broken line is located at the intersection of the volute profile line and the negative half-axis of the horizontal axis; the first bending angle is the included angle between the intersection line of the plane where the first bending part is located and the plane where the outlet end of the volute is located and the plane where the first cover plate is located, the first bending part is the part of the upper cover plate bent inward toward the volute with the first broken line as the boundary, and the first cover plate is the part of the upper cover plate that is not bent.

[0051] The lower cover plate is bent inward toward the volute at the diffuser section area of the volute outlet by an angle of the second bending angle with the second broken line as the boundary; wherein, the second broken line is vertically projected onto the plane rectangular coordinate system, the vertical projection of one end point of the second broken line is located in the second quadrant of the plane rectangular coordinate system, and the vertical projection of the other end point of the second broken line is located at the intersection of the volute profile line and the negative half-axis of the horizontal axis; the second bending angle is the included angle between the intersection line of the plane where the second bending part is located and the plane where the outlet end of the volute is located and the plane where the second cover plate is located, the second bending part is the part of the lower cover plate bent inward toward the volute with the second broken line as the boundary, and the second cover plate is the part of the lower cover plate that is not bent.

[0052] In this embodiment, as Figure 6 shown, taking the center of the impeller of the centrifugal fan as the origin of coordinates, an XY plane rectangular coordinate system is established. The vertical projection A1 of one end point of the first broken line is located in the second quadrant of the plane rectangular coordinate system, and the vertical projection A2 of the other end point of the first broken line is located at the intersection of the profile line of the volute and the negative half-axis of the horizontal axis.

[0053] Among them, the establishment of the plane rectangular coordinate system is not restricted. In another specific example, a plane rectangular coordinate system as Figure 7 shown can also be established. The vertical projection A1 of one end point of the first broken line is located in the first quadrant of the plane rectangular coordinate system, and the vertical projection A2 of the other end point of the first broken line is located in the second quadrant of the plane rectangular coordinate system.

[0054] As Figure 8 shown, the first bending angle α is the included angle between the intersection line of the plane where the first bending part is located and the plane where the outlet end of the volute is located and the plane where the first cover plate is located, and the second bending angle β is the included angle between the intersection line of the plane where the second bending part is located and the plane where the outlet end of the volute is located and the plane where the second cover plate is located.

[0055] Among them, in another specific example, the included angle between the plane where the first bending part is located and the plane where the first cover plate is located can also be selected as the first bending angle, and the included angle between the plane where the second bending part is located and the plane where the first cover plate is located can be selected as the first bending angle.

[0056] In an optional embodiment, the fillet radius of the first bending part is less than or equal to the width of the first gap; wherein, the first gap is the axial gap between the first cover plate and the upper end ring of the impeller of the centrifugal fan.

[0057] In an optional embodiment, the fillet radius of the second bending part is less than or equal to the width of the second gap; wherein, the second gap is the axial gap between the second cover plate and the lower end ring of the impeller.

[0058] In this embodiment, as Figure 9 shown, the fillet radius R1 of the first bending part is less than or equal to the width B1 of the first gap; the fillet radius R2 of the second bending part is less than or equal to the width B2 of the second gap. In this embodiment, the turbulence intensity in the bending regions of the upper cover plate and the lower cover plate is further reduced through the fillet design.

[0059] In an optional embodiment, the angle of the first bending angle is less than or equal to the first angle; wherein, the first angle is the angle at which the bending position of the first bending part is located in the plane of the upper disk of the impeller.

[0060] In an alternative embodiment, the angle of the second bending angle is less than or equal to a second angle; wherein, the second angle is twice the first angle.

[0061] When the volute is applied to the scenario of a range hood, the first bending angle and the second bending angle can be determined by combining the average air volume and the average total pressure efficiency under the working air volume condition and the maximum air volume condition. Among them, Figure 10 is the main effect diagram of the average air volume corresponding to different first bending angles α and second bending angles β under the working air volume condition; Figure 11 is the main effect diagram of the average total pressure efficiency corresponding to different first bending angles α and second bending angles β under the working air volume condition; Figure 12 is the main effect diagram of the average air volume corresponding to different first bending angles α and second bending angles β under the maximum air volume condition; Figure 13 is the main effect diagram of the average total pressure efficiency corresponding to different first bending angles α and second bending angles β under the maximum air volume condition.

[0062] In this embodiment, when the angle of the first bending angle is less than or equal to the first angle, as Figure 10 and 11 shown, for the whole range hood under the working air volume condition, the first bending angle α shows a positive correlation trend with the air volume and the total pressure efficiency; as Figure 12 and 13 shown, for the whole range hood under the maximum air volume condition, the first bending angle α shows a negative correlation trend with the air volume and the total pressure efficiency.

[0063] In this embodiment, when the angle of the second bending angle is less than or equal to the second angle, as Figure 10 and 11 shown, for the whole range hood under the working air volume condition, the second bending angle β shows a positive correlation trend with the air volume and the total pressure efficiency; as Figure 12 and 13 shown, for the whole range hood under the maximum air volume condition, the second bending angle β shows a negative correlation trend with the air volume and the total pressure efficiency.

[0064] In an alternative embodiment, the angle of the first bending angle is equal to the first angle, and the second bending angle is twice the first bending angle.

[0065] In this embodiment, when the angle of the first bending angle is equal to the first angle and the angle of the second bending angle is equal to twice the angle of the first bending angle, the performance of the volute is further improved.

[0066] Embodiment 2

[0067] Figure 14Schematic diagram of the structure of a centrifugal fan provided in this embodiment. The centrifugal fan includes a volute 201 as described in Embodiment 1.

[0068] In this embodiment, by bending the upper cover plate and / or the lower cover plate in the diffuser section area at the outlet of the volute towards the inner side of the volute to form an approximately trapezoidal cross-section, the flow state of the air flow in the volute outlet area is improved, and the eddy current loss is reduced.

[0069] In an alternative embodiment, as Figure 14 shown, the centrifugal fan includes an air outlet hood 202. The inlet end of the air outlet hood is connected to the outlet end of the volute, and the inlet cross-section of the air outlet hood matches the outlet cross-section of the volute.

[0070] In this embodiment, the inlet cross-section of the air outlet hood matches the outlet cross-section of the volute, better matching the oncoming flow of the gas at the volute outlet, and further realizing the improvement of the performance of the centrifugal fan and the reduction of noise.

[0071] Embodiment 3

[0072] This embodiment provides a range hood, and the range hood includes the centrifugal fan as described in Embodiment 2. Since there is an axial dynamic and static interference gap between the volute and the impeller, the circumferential vortex pair flow will generate leakage loss here; especially under the working air volume condition, due to the increase in pressure inside the volute, the leakage loss increases. However, in this embodiment, the centrifugal fan of the range hood applies the volute as described in Embodiment 2. For the above-mentioned vortex pair flow loss and dynamic and static interference gap, the upper cover plate and / or the lower cover plate of the volute are bent towards the inner side of the volute in the diffuser section area at the outlet of the volute to form an approximately trapezoidal cross-section, improving the flow state of the air flow in the volute outlet area and reducing the eddy current loss. Therefore, this range hood can take into account the performance and noise under two conditions, namely the working air volume condition and the maximum air volume condition.

[0073] Although the specific embodiments of the present invention have been described above, those skilled in the art should understand that this is only for illustration. The protection scope of the present invention is defined by the appended claims. Without departing from the principles and essence of the present invention, those skilled in the art can make various changes or modifications to these embodiments, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A volute of a centrifugal fan, characterized in that: The volute comprises an annular wall, an upper cover plate and a lower cover plate, wherein the upper cover plate is connected to the lower cover plate through the annular wall; The upper cover plate is located in the diffuser section area of ​​the volute outlet and is bent toward the inner side of the volute; and / or, The lower cover plate is located in the diffuser section area of ​​the volute outlet and is bent toward the inner side of the volute.

2. The volute according to claim 1, characterized in that: Take the impeller center of the centrifugal fan as the coordinate origin and establish a plane rectangular coordinate system; The upper cover plate is located in the diffuser section area of ​​the volute outlet and is bent toward the inner side of the volute at a first bending angle with the first fold line as the boundary; wherein, the first fold line is vertically projected onto the plane rectangular coordinate system, the vertical projection of one end point of the first fold line is located in the second quadrant of the plane rectangular coordinate system, and the vertical projection of the other end point of the first fold line is located at the intersection of the volute profile line and the negative semi-axis of the horizontal axis; the first bending angle is the angle between the intersection of the plane where the first bending portion is located and the plane where the outlet end of the volute is located and the plane where the first cover plate is located, the first bending portion is the portion of the upper cover plate that is bent toward the inner side of the volute with the first fold line as the boundary, and the first cover plate is the portion of the upper cover plate that is not bent; and / or, The lower cover plate is located in the diffusion section area of ​​the volute outlet and is bent toward the inner side of the volute at a second bending angle with the second fold line as the boundary; wherein, the second fold line is vertically projected onto the plane rectangular coordinate system, the vertical projection of one end point of the second fold line is located in the second quadrant of the plane rectangular coordinate system, and the vertical projection of the other end point of the second fold line is located at the intersection of the volute profile line and the negative semi-axis of the horizontal axis; the second bending angle is the angle between the intersection of the plane where the second bending portion is located and the plane where the outlet end of the volute is located and the plane where the second cover plate is located, the second bending portion is the portion of the lower cover plate that is bent toward the inner side of the volute with the second fold line as the boundary, and the second cover plate is the portion of the lower cover plate that is not bent.

3. The volute according to claim 2, characterized in that: The fillet radius of the first bending portion is less than or equal to the width of the first gap; wherein the first gap is the axial gap between the first cover plate and the upper end ring of the impeller of the centrifugal fan.

4. The volute according to claim 2, characterized in that: The fillet radius of the second bending portion is less than or equal to the width of the second gap; wherein the second gap is the axial gap between the second cover plate and the lower end ring of the impeller.

5. The volute according to claim 2, characterized in that: The angle of the first bending angle is less than or equal to the first angle; wherein, the first angle is the angle at which the bending position of the first bending portion is located in the plane where the impeller upper plate is located.

6. The volute according to claim 5, characterized in that: The second bending angle is less than or equal to a second angle; wherein the second angle is twice the first angle.

7. The volute according to claim 6, characterized in that: The first bending angle is equal to the first angle, and the second bending angle is twice the first bending angle.

8. A centrifugal fan, characterized in that: The centrifugal fan comprises a volute as described in any one of claims 1-7.

9. The centrifugal fan according to claim 8, characterized in that: The centrifugal fan comprises an air outlet hood, the inlet end of the air outlet hood is connected to the outlet end of the volute, and the inlet cross section of the air outlet hood matches the outlet cross section of the volute.

10. A range hood, characterized in that: The range hood comprises the centrifugal fan as claimed in claim 8 or 9.

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