CN218093632U - Centrifugal fan and range hood - Google Patents

Abstract

The utility model relates to a centrifugal fan and range hood, include: a volute; the impeller is arranged in the volute and provided with a first axis extending forwards and backwards; the current collector is arranged at an air inlet of the volute, comprises a flow guide part and a radial flow guide part, the projection of the radial outer side of the radial flow guide part in the axial direction is recorded as a first projection, the first projection is a circle, and the center of the first projection is positioned on a first axis of the impeller; the projection of the radial inner side of the radial flow guide part in the axial direction is marked as a second projection, the second projection is an ellipse, the long axis of the second projection basically extends vertically, and the geometric center of the second projection is positioned on one side, away from the air outlet, of the circle center of the first projection. The variable cross-section flow collector is formed, the flow separation of the area below the inlet of the flow collector can be reduced, the speed gradient distribution is reduced, and the effective air inlet area at the inlet of the fan is increased, so that the working efficiency of the range hood is improved in the whole working condition range, and the working noise is reduced.

Description

Centrifugal fan and range hood

Technical Field

The utility model relates to a centrifugal fan technical field especially relates to a centrifugal fan and range hood, further relates to a centrifugal fan is vertical arrangement's european style range hood.

Background

The centrifugal fan is an important air supply device and is commonly used in products such as a range hood, an air conditioner and the like. The centrifugal fan is generally composed of a collector, a volute, an impeller, a motor and the like. The current collector is used as an important component of the fan, is arranged at an air inlet of the fan, is in a ring shape and generally comprises an installation part, a radial flow guide part and an axial flow guide part, and has the functions of ensuring that gas smoothly and uniformly enters the impeller, reducing flow loss and improving the efficiency of the fan. If the collector is not designed reasonably, the inlet condition is deteriorated, the performance of the fan is reduced, and the pneumatic performance and the noise of the range hood are influenced.

Because part of high-pressure gas in the volute is easy to leak from a dynamic and static junction area of the impeller and the volute and flows back to the impeller again, the efficiency is reduced and the noise is increased. In order to improve the problem, for example, the Chinese patent with the application number of CN201910463522.8 (the granted publication number of CN 110145481B) discloses an air inlet ring disclosed in the specification of a centrifugal fan applying the air inlet ring, wherein the inner circle and the outer circle of the air inlet ring are eccentric to form the air inlet ring with a variable cross section, so that the vortex at the air inlet is more stable, the strength is higher, the position and the distribution range of the vortex move towards the center of an impeller, the flow is increased in the whole working condition range, and the efficiency is improved. And when the air inlet extends forwards and the axis of the impeller horizontally extends from front to back, the included angle between the connecting line between the second circle center and the first circle center and the horizontal direction is 0-60 degrees, and the second circle center is positioned on one side of the first circle center, which is far away from the air outlet.

However, because of the different application scenarios of the centrifugal fans, especially in the european range hood, the centrifugal fan is generally vertically installed in the fan frame, the current collector guides the airflow flowing from bottom to top into the fan to play a role in guiding the airflow, the air near the lower area of the air inlet of the fan is not easy to enter the impeller flow channel through a large flow turn, and the impeller always keeps high-speed rotation, so that the flow separation and turbulence are easy to occur in the lower area of the air inlet of the fan, and turbulence noise is caused. Meanwhile, in the European-style range hood, the air inflow of the corresponding area at the lower part of the air inlet is relatively more, the air inlet of the upper area of the air inlet is relatively less, and the circular current collector scheme in the patent can aggravate the condition that the air inlet of the upper area of the air inlet is relatively less, so that the working efficiency of the impeller is low, and the pneumatic performance and the noise of the centrifugal fan are influenced. In addition, because a certain movement gap exists between a rotating component (impeller) and a static component (volute) of the centrifugal fan, when the impeller rotates, pressure difference is generated between two sides of the gap, and partial fluid leaks from a high-pressure side to a low-pressure side through the gap.

Therefore, further improvement is needed in the existing centrifugal fan.

SUMMERY OF THE UTILITY MODEL

The utility model discloses the first technical problem that will solve is to prior art's current situation, provides one kind and can improve the flow state of centrifugal fan entry, reduces separation and torrent problem that flows, and then improves the centrifugal fan of aerodynamic performance.

The utility model discloses the second technical problem that solve provides an use above-mentioned centrifugal fan's range hood to prior art's current situation.

The utility model provides a technical scheme that first technical problem adopted does: a centrifugal fan, comprising:

the front side of the volute is provided with an air inlet, and the upper part of the volute is provided with an air outlet;

the impeller is arranged in the volute and is provided with a first axis extending forwards and backwards;

the flow collector is arranged at an air inlet of the volute and comprises a flow guide part, the flow guide part comprises a radial flow guide part, the projection of the radial outer side of the radial flow guide part in the axial direction is recorded as a first projection, the first projection is a circle, and the center of the first projection is positioned on the first axis of the impeller;

the projection of the radial inner side of the radial flow guide part in the axial direction is marked as a second projection, the second projection is an ellipse, the long axis of the second projection basically extends vertically, and the geometric center of the second projection is positioned on one side, away from the air outlet, of the circle center of the first projection.

Generally, the radial inner side of the radial flow guiding part of the current collector is set to be an ellipse-like structure which is wide in the upper part and wide in the lower part and narrow in the left part and the right part, so that the flow state of the inlet of the centrifugal fan can be effectively improved, in order to better match with a top-suction range hood (euro type machine) with a vertically arranged fan, the distribution condition of the flow field of the circumferential direction of the current collector is further improved and optimized, the projection of the inner side of the impeller in the axial direction is recorded as a third projection, the third projection is a circle, the lowest point of the second projection is coincided with the lowest point of the third projection, the highest point of the second projection is positioned below the highest point of the third projection, along the radial direction of the third projection, the second projection is provided with a first characteristic point corresponding to a point on the third projection, the distance from the first characteristic point of the second projection to a point corresponding to the third projection is recorded as a first distance, and the first distance is gradually increased from the lowest point to the highest point of the second projection.

The first distance should be reasonably designed, and particularly, the first distance between the highest point on the second projection and the highest point of the third projection is too small, the improvement situation of the flow state of the centrifugal fan inlet is not obvious, the first distance at this position is too large, which affects the air volume of the centrifugal fan inlet, the first distance between the highest point on the second projection and the highest point of the third projection is d1, where the value range of d1 is: 6-15 mm.

In order to improve the circumferential flow field distribution condition of the current collector, a contour line obtained by sectioning a radial flow guide part of the current collector on a plane passing through a first axis of the impeller is marked as a first curve, 4 control points are distributed on the first curve, a flow guide surface starting point Pg, a height control point Ph, a curvature control point Pc and a flow guide surface cut-off point Pd are respectively arranged along the flow direction of an air flow, the starting point Pg is positioned at the position of the radial outer side of the radial flow guide part, and the flow guide surface cut-off point Pd is positioned at the position of the radial inner side of the radial flow guide part, the curvature control point Pc is located on a plane where a front side wall of the volute is located, the radial distance between the curvature control point Pc and a guide surface starting point Pg is c, the height control point is located on a middle axis m between the starting point Pg and a guide surface cut-off point Pd, the vertical distance between the height control point Ph and the plane where the front side wall of the volute is located is h, and the radial distance between the curvature control point Pc and the guide surface cut-off point Pd is l, wherein h and l of each first curve corresponding to the radial guide part in the circumferential direction are equal, and h = 8-21mm, l = 1-3 mm.

In order to better improve the state of the local flow field, a guide surface starting point Pg, a height control point Ph, a curvature control point Pc and a guide surface cutoff point Pd on the first curve are smoothly connected by adopting a Bezier curve.

In order to facilitate structural design of the current collector and better match the flow state of the whole machine under different operating conditions, the distance between a plane M of the radial inner side of the radial flow guide part and the front disc of the impeller is M, wherein the value range of M is as follows: 4-5 mm.

For the size looks adaptation with centrifugal fan's impeller, the impeller radius is R2, the radius Rg of the first projection of radial guiding part, wherein, rg = R2+ R0, R0's value range is: 10-20 mm.

In order to better match the flowing state of the whole machine under different operating conditions, the flow guide part further comprises an axial flow guide part extending from the radial flow guide part along the first axis towards the inside of the volute, and the axial height of the axial flow guide part is gradually increased from bottom to top of the axial flow guide part.

The depth of the axial flow guide part extending into the impeller is increased, so that backflow can be restrained, the flow speed of the air inlet is large, the axial effective air inlet height of the blades can be reduced due to the overlong axial flow guide part, performance loss is caused, the matching relation between the structure of the flow collector and the impeller needs to be reasonably designed aiming at the characteristic that the flow speed of the bottom of the flow collector is large, gas separation is reduced, the air quantity is increased, the upper part of the axial flow guide part is overlapped with the impeller in the up-down direction, and a gap is reserved between the lower part of the axial flow guide part and the front disc of the impeller.

In order to reduce the air inlet resistance and improve the state of a local flow field better, the axial flow guide part is smoothly connected with the radial flow guide part, the current collector further comprises an annular installation part positioned outside the flow guide part, and the annular installation part is smoothly connected with the radial flow guide part.

The utility model provides a technical scheme that second technical problem adopted does: a range hood comprises a casing and the centrifugal fan, wherein the centrifugal fan is arranged in the casing, and a first axis of an impeller of the centrifugal fan extends horizontally.

Compared with the prior art, the utility model has the advantages that: the radial inner side of the radial flow guide part of the flow collector is provided with the circular structure, the radial outer side of the radial flow guide part is provided with the elliptical structure, the flow collector with the variable cross section is formed, the flow separation of the lower region of the inlet of the flow collector can be reduced, the speed gradient distribution is reduced, the effective air inlet area of the inlet of the fan is increased, and therefore the working efficiency of the range hood is improved and the working noise is reduced in the whole working condition range, particularly the large-flow working condition. Particularly, when the centrifugal fan is vertically placed in a fan frame of the range hood, on one hand, the flow separation of gas flowing from the fan frame to a fan inlet can be reduced, and the effective flow area is increased; on the other hand, the turbulent flow state of the air in the upper area in the fan frame can be improved, and the turbulent flow noise is reduced.

Drawings

Fig. 1 is a schematic perspective view of a current collector according to an embodiment of the present invention;

fig. 2 is a front view of a current collector according to an embodiment of the present invention;

fig. 3 is a rear view of a current collector of an embodiment of the present invention;

fig. 4 is a schematic structural diagram of a state of the current collector and the impeller in cooperation according to an embodiment of the present invention;

fig. 5 is a cut-away perspective view of a current collector in accordance with an embodiment of the present invention;

FIG. 6 is a schematic view of the structure of FIG. 3 without the sound absorbing member;

fig. 7 is a front view of a centrifugal fan according to an embodiment of the present invention;

FIG. 8 isbase:Sub>A cross-sectional view taken at A-A of FIG. 7;

fig. 9 is a schematic perspective view of a range hood according to an embodiment of the present invention (only the casing is shown);

fig. 10 is a speed cloud chart comparing the range hood according to the embodiment of the present invention with the existing range hood;

fig. 11 is a pressure cloud chart comparing the range hood of the embodiment of the present invention with the existing range hood.

Detailed Description

The present invention will be described in further detail with reference to the following embodiments.

Terms indicating directions, such as "front", "rear", "upper", "lower", "left", "right", "side", "top", "bottom", and the like, are used in the specification and claims of the present invention to describe various example structural parts and elements of the present invention, but these terms are used herein only for convenience of description and are determined based on example orientations shown in the drawings. Because the disclosed embodiments may be oriented in different directions, the directional terms are used for descriptive purposes and are not intended to be limiting, e.g., "upper" and "lower" are not necessarily limited to directions opposite or coincident with the direction of gravity.

Referring to fig. 1 to 11, a collector for a centrifugal fan, which is arranged at an air inlet 41 of the centrifugal fan, comprises a deflector ring 10 and a sound absorbing member 30. The deflector ring 10 includes an annular mounting portion 11 and a deflector portion.

Referring to fig. 1, the annular mounting portion 11 has a central axis 110, and opposite first and second directions A1 and A2 are formed along the central axis 110, wherein a direction of the soot flow path is taken as the second direction A2. The flow guide portion comprises a radial flow guide portion 12 and an axial flow guide portion 13, and the radial flow guide portion 12 is an arc-shaped wall which extends from the inner side of the annular installation portion 11 to the inner side in a radial direction and protrudes in a bending mode towards the first direction A1. The axial flow guide 13 is an annular wall formed by the inner side of the radial flow guide 12 extending in the second direction A2.

In order to reduce aerodynamic noise, especially low and medium frequency noise, at the air inlet 41, one side (i.e. leeward side) of the first flow guiding portion facing away from the incoming airflow direction is provided with noise reduction unit cavities sequentially arranged at intervals along the circumferential direction of the first flow guiding portion, wherein each noise reduction unit cavity is filled with a sound absorption member 30. The sound absorbing member 30 may be made of various porous sound absorbing materials in the prior art, and the sound absorbing member 30 of the present embodiment is preferably made of polyurethane sound absorbing cotton in order to ensure the service life of the sound absorbing member 30. The first deflector has an adhesive coating on the lee side for fixing the sound absorbing member 30 filled in the cavity of the noise reducing unit.

Referring to fig. 8, the leeward side of the first deflector further has a first annular partition 121 and a second annular partition 122 extending along the second direction A2 and spaced apart from each other in the radial direction of the deflector ring 10. The first annular partition 121 and the second annular partition 122 each extend in the second direction A2, and the first annular partition 121 and the second annular partition 122 are disposed substantially coaxially.

Referring to fig. 5 and 6, the first annular partition plate 121 is located outside the second annular partition plate 122, and a first annular cavity 21 is defined between the first annular partition plate and the second annular partition plate, first partition plates 126 are further disposed in the first annular cavity 21 along the circumferential direction, and each first partition plate 126 divides the first annular cavity 21 into a plurality of first noise reduction cavities 210, where the first partition plates 126 are uniformly distributed along the circumferential direction of the first annular cavity 21 at intervals. In addition, a second annular cavity 22 located outside the first annular cavity 21 is defined between the first annular partition 121 and a portion of the radial flow guide part 12 away from the axial flow guide part 13 (i.e., an outer portion of the radial flow guide part 12 in the radial direction), and second partition plates 127 arranged at intervals in sequence are further disposed in the second annular cavity 22 along the circumferential direction, and each second partition plate 127 partitions the second annular cavity 22 into a plurality of second noise reduction cavities 220. A third annular cavity 23 located inside the first annular cavity 21 is defined between the second annular partition 122 and a portion of the radial flow guide portion 12 adjacent to the axial flow guide portion 13 (i.e., an inner portion of the radial flow guide portion 12 in the radial direction), third partition plates 128 are further circumferentially arranged inside the third annular cavity 23 at intervals, and each third partition plate 128 divides the third annular cavity 23 into a plurality of third noise reduction cavities 230. The first noise reduction cavity 210, the second noise reduction cavity 220 and the third noise reduction cavity 230 form the noise reduction unit cavity of the radial flow guide portion 12 of the present embodiment.

Since the aerodynamic noise is the main noise source of the fan and comprises the discrete noise and the broadband vortex noise generated by periodically induced unsteady force, the arrangement of the noise reduction unit cavities uniformly arranged in the circumferential direction can enable the collector to obtain relatively better broadband sound absorption characteristics on the whole. The number of the first noise reduction cavities 210 in the first annular cavity 21, the number of the second noise reduction cavities 220 in the second annular cavity 22, and the number of the third noise reduction cavities 230 in the third annular cavity 23 are the same, and are all n, wherein n is greater than or equal to 6, so that the volume of the noise reduction unit cavity is relatively small, noise reduction frequency is facilitated to approach to medium and low frequency within a certain range, and the fan noise frequency can be well matched. Still further, in the present embodiment, the first noise reduction cavities 210, the second noise reduction cavities 220, and the third noise reduction cavities 230 are arranged in a staggered manner in the radial direction of the flow guide ring 10. In order to ensure the consistency of the noise reduction effect of the current collector in the circumferential direction, the widths of the first annular cavity 21 and the second annular cavity 22 in the radial direction are substantially consistent, which is denoted by t, where the value range of t is: 2-4 mm. While the radial width of the third annular groove varies (in particular, in cooperation with the radially inner oval configuration of the radial flow guide 12), as can be seen in fig. 5, the width of the top of the third annular groove is greater than the width of the bottom. In particular, the second annular partition 122 has a minimum distance tn from the radially inner side of the radial flow guide 12, tn preferably being 2mm, see in particular fig. 6.

In the present embodiment, the dimensions of the first annular partition, the second annular partition, the first partition 126, the second partition 127 and the third partition 128 in the axial direction of the baffle ring 10 need to be limited so that the current collector is mounted on the front cover plate of the blower scroll 40, wherein the rear end of the first annular partition, the rear end of the second annular partition, the rear end of each first partition 126, the rear end of each second partition 127 and the rear end of each third partition 128 are located on the same plane parallel to the plane of the annular mounting portion 11. Further, in order to reduce the end face leakage of the fan, the outer surface (i.e., the rear end face) of the sound absorbing member 30 filled in the noise reduction unit cavity is a flat surface which is flush with the inner wall surface of the upper cover plate of the scroll case 40, as shown in detail in fig. 8.

Referring to fig. 6, the wall thickness of the first, second, first, second and third annular separators 126, 127 and 128 in this embodiment is δ, which corresponds to the wall thickness of the header, where δ = 1-2 mm. Wherein the first, second, first, second and third annular separator plates 126, 127 and 128 are designed in one piece with the body of the collector.

In the present embodiment, the noise reduction unit cavities arranged at intervals in the circumferential direction on the leeward side of the radial flow guide part 12 of the collector and the sound absorption member 30 filled therein constitute an acoustic liner device, which can better eliminate turbulent noise of the collector back cavity, wherein the volume of the noise reduction unit cavities is relatively small, which is beneficial to the approach of noise reduction frequency to middle and low frequencies in a certain range, and can better match with fan noise frequency.

Referring to fig. 7 and 8, the present embodiment further relates to a centrifugal fan, which includes a volute 40, an impeller 50, a motor and the above-mentioned collector. The impeller 50 is disposed inside the volute 40 and is rotated by a motor.

An air inlet 41 is formed on the front side (i.e. the front cover plate) of the scroll casing 40, and an air outlet 42 is formed on the upper portion of the scroll casing 40. The impeller 50 has a first axis O extending back and forth, see fig. 9.

The projection of the radial outer side of the radial flow guide 12 of the collector in the axial direction is denoted as a first projection 123, the first projection 123 is a circle, and the center O1 of the first projection 123 is located on the first axis O of the impeller 50. The projection of the radial inner side of the radial flow guide 12 in the axial direction is denoted as a second projection 124, which second projection 124 is an ellipse. In a state where the collector is assembled to the air outlet 42 of the volute 40 of the centrifugal fan, the major axis a of the second projection 124 extends substantially vertically (the minor axis extends substantially horizontally), and the geometric center O2 of the second projection 124 is located on a side of the center of the first projection 123 away from the air outlet 42 (i.e., is arranged below the first axis O of the impeller 50).

Generally, the radial inner side of the radial flow guiding portion 12 of the collector is configured to be an ellipse-like structure with a wide upper portion and a wide lower portion and a narrow left portion and a narrow right portion, so as to effectively improve the flow state of the inlet of the centrifugal fan, and in order to better match a top-suction range hood (euro-type machine) with a vertically disposed fan, and further improve and optimize the flow field distribution of the circumferential direction of the collector, a projection of the inner side of the impeller 50 in the axial direction is denoted as a third projection 51, the third projection 51 is a circle, wherein a lowest point of the second projection 124 coincides with a lowest point of the third projection 51, a highest point of the second projection 124 is located below the highest point of the third projection 51, along the radial direction of the third projection 51, a first characteristic point corresponding to a point on the third projection 51 is provided on the second projection 124, a distance from the first characteristic point of the second projection 124 to a point on the third projection 51 corresponding to the first characteristic point is denoted as a first distance, and the first distance is gradually increased from the lowest point to the highest point of the second projection 124.

Referring to fig. 3, the first distance should be reasonably designed, and in particular, the first distance dn between the highest point on the second projection 124 and the highest point of the third projection 51 is too small, the improvement condition of the flow state of the centrifugal fan inlet is not obvious, the first distance is too large, the air volume of the centrifugal fan inlet is affected, and the first distance between the highest point on the second projection 124 and the highest point of the third projection 51 is d1, where the value range of d1 is: 6-15 mm.

In particular, the contour of the radial flow guide 12 of the collector, cut in a plane Sn passing through the first axis O of the impeller 50 (which may be understood as a meridian control surface of the impeller 50), is denoted as a first curve 125. As shown in fig. 2 and 3, feature points are drawn at intervals of 45 ° through a first axis O of the impeller 50 to form 8 sub-noon control surfaces, the feature points are P1, P2 \ 8230 \ P8, and corresponding meridian control surfaces are S1, S2 \ 8230 \ 8230: \ 8230and S8, respectively, starting from 12 points in the clockwise direction.

Each first curve 125 is distributed with 4 control points, which are a guide surface starting point Pg, a height control point Ph, a curvature control point Pc and a guide surface cut-off point Pd along the flowing direction of the air flow, the starting point Pg is located at the position of the radial outer side of the radial guide part 12, the guide surface cut-off point Pd is located at the position of the radial inner side of the radial guide part 12, the curvature control point Pc is located on the plane of the front side wall of the volute 40, the radial distance between the curvature control point Pc and the guide surface starting point Pg is c, the height control point is located on the middle axis m between the starting point Pg and the guide surface cut-off point Pd, the vertical distance between the height control point Ph and the plane of the front side wall of the volute 40 is h, the radial distance between the curvature control point Pc and the guide surface cut-off point Pd is l, wherein h and l of each first curve 125 corresponding to the radial guide part 12 in the circumferential direction are equal, and h = 8-1mm, l = 1-3 mm.

In order to facilitate the introduction of the gas into the fan and to reduce the flow separation at the fan inlet, the curved surfaces of the radial flow guiding portions 12 of the flow collectors are mixed by the characteristic curve boundaries on the meridian control surfaces. In order to better improve the state of the local flow field, a guide surface starting point Pg, a height control point Ph, a curvature control point Pc and a guide surface cutoff point Pd on the first curve 125 are smoothly connected by a bezier curve. More specifically, the axial flow guiding part 13 of the current collector is smoothly connected with the radial flow guiding part 12, and the annular mounting part 11 of the current collector is smoothly connected with the radial flow guiding part, so that the air inlet resistance can be reduced, and the local flow field state can be better improved.

As shown in fig. 2, the radius of the impeller 50 of the centrifugal fan in this embodiment is R2, and the radius Rg of the first projection 123 of the radial flow guiding portion 12, where Rg = R2+ R0, and the range of R0 is: 10-20 mm. The distance between the radial inner plane M of the radial flow guide part 12 and the front disc of the impeller 50 is M1, wherein the value range of M1 is as follows: 4-5 mm.

As can be seen from fig. 4 and 8, the axial height of the axial flow guide portion 13 of the present embodiment gradually increases from bottom to top. The effect of restraining backflow can be achieved by increasing the depth of the axial flow guide part extending into the impeller 50, but the flow velocity at the air inlet 41 is high, and the effective air inlet height in the axial direction of the blade can be reduced if the axial flow guide part is too long, so that performance loss is caused, and aiming at the characteristic that the flow velocity at the bottom of the current collector is relatively high, the matching relationship between the structure of the current collector and the impeller 50 needs to be reasonably designed to reduce gas separation and improve air volume, therefore, the upper part of the axial flow guide part 13 of the embodiment is overlapped with the impeller 50 in the up-down direction, and a gap Q is formed between the lower part of the axial flow guide part 13 and a front disc of the impeller 50. In particular, the amount of the solvent to be used,

the axial flow guide part 13 axially extends towards the inside of the volute 40 at a collector outlet area corresponding to P1, P2, P3, 8230A and P8, wherein the distances from each control point to the front disc surface of the impeller 50 are b1, b2, b3, 8230A and b8 in sequence. Where-4 mm = b1 < b2= b8 < b3= b7=0 < b4= b6 < b5 < m, a distance b1 between the upper portion of the axial flow guide 13 and the front disk surface of the impeller 50 is shown in fig. 4 (the upper portion of the axial flow guide 13 and the impeller 50 overlap in the up-down direction, and therefore takes a negative value). Other distances b2, b3, \ 8230 \ 8230; b8 can be analogized.

Fig. 9 shows a top-suction type range hood, which includes a casing 60 and the above-mentioned centrifugal fan, the centrifugal fan is disposed in the casing 60, and the first axis O of the impeller 50 of the centrifugal fan extends horizontally.

The radial inner side of the radial flow guide part 12 of the flow collector is provided with the circular structure, the radial outer side of the radial flow guide part 12 is provided with the elliptical structure, the flow collector with the variable cross section is formed, the flow separation of the lower region of the inlet of the flow collector can be reduced, the speed gradient distribution is reduced, the effective air inlet area at the inlet of the fan is increased, and therefore the working efficiency of the range hood is improved and the working noise is reduced within the whole working condition range, particularly the large-flow working condition. Particularly, when the centrifugal fan is vertically placed in a fan frame of the range hood, on one hand, the flow separation of gas flowing from the fan frame to a fan inlet can be reduced, and the effective flow area is increased; on the other hand, the turbulent flow state of the air in the upper area in the fan frame can be improved, and the turbulent flow noise is reduced. In addition, the collector has designed the sealed device of making an uproar that falls that mutually supports with impeller 50 at the leeward side, has promoted the gas tightness of fan, has reduced inside terminal surface leakage problem to utilize and inhale sound piece 30 and carry out choked flow and sound absorption, further reduce backward flow and noise problem, promoted fan efficiency and reduced the complete machine noise.

The effect of the current collector of this embodiment on improving the inlet of the fan of the european style range hood is shown in fig. 10 and fig. 11, the left drawings are the techniques of this embodiment, and the right drawings are the prior art (the projections of the radial inner side and the radial outer side of the radial flow guide portion 12 in the axial direction are both circles). As can be seen from the speed cloud chart in fig. 8 and the pressure cloud chart in fig. 9, the air volume of the european style range hood adopting the embodiment is improved to a certain extent in the bottom area of the fan inlet, mainly because the characteristic curve of the current collector in the embodiment on the circumferential control plane is designed according to the flow characteristic of the fan inlet, particularly in the bottom area of the fan inlet, the vertically upward air flow can better adhere to the flow guide surface of the current collector to enter the fan, so that the flow separation at the position is reduced. In addition, in the top region in the fan frame, the current collector of this embodiment is adopted to compare prior art and has reduced the air current stagnation region to weaken turbulence intensity, promote the performance of lampblack absorber, reduce the complete machine noise.

Claims (11)

1. A centrifugal fan, comprising:

the front side of the volute (40) is provided with an air inlet (41), and the upper part of the volute is provided with an air outlet (42);

an impeller (50) disposed within the volute (40) and having a first axis (O) extending fore and aft;

the flow collector is arranged at an air inlet (41) of the volute (40) and comprises a flow guide part, the flow guide part comprises a radial flow guide part (12), the projection of the radial outer side of the radial flow guide part (12) in the axial direction is marked as a first projection (123), the first projection (123) is a circle, and the center of the first projection (123) is positioned on a first axis (O) of the impeller (50);

the method is characterized in that: the projection of the radial inner side of the radial flow guide part (12) in the axial direction is marked as a second projection (124), the second projection (124) is an ellipse, the long axis of the second projection (124) extends vertically basically, and the geometric center of the second projection (124) is positioned on one side, away from the air outlet (42), of the circle center of the first projection (123).

2. The centrifugal fan of claim 1, wherein: the projection of the inner side of the impeller (50) in the axial direction is recorded as a third projection (51), the third projection (51) is a circle, the lowest point of the second projection (124) coincides with the lowest point of the third projection (51), the highest point of the second projection (124) is located below the highest point of the third projection (51), and along the radial direction of the third projection (51), the second projection (124) has a first feature point corresponding to a point on the third projection (51), the distance from the first feature point of the second projection (124) to the point on the third projection (51) corresponding to the first feature point is recorded as a first distance, and the first distance gradually increases from the lowest point to the highest point of the second projection (124).

3. The centrifugal fan of claim 2, wherein: a first distance between a highest point on the second projection (124) and a highest point of the third projection (51) is d1, wherein a value range of d1 is as follows: 6-15 mm.

4. The centrifugal fan according to any one of claims 1 to 3, wherein: a contour line obtained by sectioning a radial flow guide part (12) of the flow collector on a plane passing through a first axis (O) of the impeller (50) is marked as a first curve (125), 4 control points are distributed on the first curve (125), and a flow guide surface starting point Pg, a height control point Ph, a curvature control point Pc and a flow guide surface cut-off point Pd are respectively arranged along the flow direction of air flow, wherein the starting point Pg is positioned at the position of the radial outer side of the radial flow guide part (12), and the flow guide surface cut-off point Pd is positioned at the position of the radial inner side of the radial flow guide part (12), the curvature control point Pc is located on a plane where a front side wall of the volute (40) is located, the radial distance between the curvature control point Pc and a guide surface starting point Pg is c, the height control point is located on a middle axis m between the starting point Pg and a guide surface cut-off point Pd, the vertical distance between the height control point Ph and the plane where the front side wall of the volute (40) is located is h, and the radial distance between the curvature control point Pc and the guide surface cut-off point Pd is l, wherein h and l of each first curve (125) corresponding to the radial guide portion (12) in the circumferential direction are equal, and h = 8-12mm, l = 1-3 mm.

5. The centrifugal fan of claim 4, wherein: and the starting point Pg of the flow guide surface, the height control point Ph, the curvature control point Pc and the cutoff point Pd of the flow guide surface on the first curve (125) are smoothly connected by a Bezier curve.

6. The centrifugal fan according to any one of claims 1 to 3, wherein: the distance between a plane M of the radial inner side of the radial flow guide part (12) and a front disc of the impeller (50) is M, wherein the value range of M is as follows: 4-5 mm.

7. The centrifugal fan according to any one of claims 1 to 3, wherein: the radius of the impeller (50) is R2, and the radius Rg of the first projection (123) of the radial guide part (12), wherein Rg = R2+ R0, and the value range of R0 is as follows: 10-20 mm.

8. The centrifugal fan according to any one of claims 1 to 3, wherein: the water conservancy diversion portion still includes certainly radial water conservancy diversion portion (12) are followed axial water conservancy diversion portion (13) that first axis (O) extend towards the inside of spiral case (40), the axial height of axial water conservancy diversion portion (13) certainly axial water conservancy diversion portion (13) from bottom to top increases gradually.

9. The centrifugal fan of claim 8, wherein: the upper part of the axial flow guide part (13) is overlapped with the impeller (50) in the vertical direction, and a gap is reserved between the lower part of the axial flow guide part (13) and a front disc of the impeller (50).

10. The centrifugal fan of claim 8, wherein: axial water conservancy diversion portion (13) with radial water conservancy diversion portion (12) smooth phase to each other, the collector still including being located annular installation department (11) outside the water conservancy diversion portion, this annular installation department (11) with radial water conservancy diversion smooth phase to each other.

11. A range hood, its characterized in that: comprising a casing (60) and a centrifugal fan according to any one of claims 1-10, which is arranged in the casing (60) and the first axis (O) of the impeller (50) of which extends horizontally.

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