CN111852905B

CN111852905B - Centrifugal fan and range hood with same

Info

Publication number: CN111852905B
Application number: CN202010618468.2A
Authority: CN
Inventors: 胡承杰; 王伟; 张鲁涛
Original assignee: Ningbo Fotile Kitchen Ware Co Ltd
Current assignee: Ningbo Fotile Kitchen Ware Co Ltd
Priority date: 2020-06-30
Filing date: 2020-06-30
Publication date: 2022-01-25
Anticipated expiration: 2040-06-30
Also published as: CN111852905A

Abstract

The invention discloses a centrifugal fan, which comprises a volute, an impeller and a current collector, wherein the impeller and the current collector are arranged in the volute, an air inlet is formed in the volute, the current collector is arranged at the air inlet, the impeller and the current collector have a common axis, the current collector comprises an annular installation part connected with the volute and a flow guide part used for guiding airflow, the flow guide part comprises a radial flow guide part extending inwards from the radial inner side of the installation part and an axial flow guide part extending inwards from the radial inner side of the radial flow guide part to the inner part of the volute after penetrating through the air inlet, the impeller comprises a front ring, a rear ring and blades arranged between the front ring and the rear ring, and the centrifugal fan is characterized in that: on the axial section of the collector, the axial flow guide part is a curve gradually expanding towards the radial outside from one end connected with the radial flow guide part towards the direction of the impeller, a concave part is formed at the end part connected with the front ring of each blade, and the concave part is formed by the radial inside of each blade sinking towards the radial outside.

Description

Centrifugal fan and range hood with same

Technical Field

The invention relates to a power system, in particular to a centrifugal fan and a range hood applying the centrifugal fan.

Background

The multi-wing centrifugal fan has the characteristics of high pressure, low noise and the like, so that the multi-wing centrifugal fan system is generally used as a power source in the society at present, and an impeller rotating at a high speed is utilized to complete two functions of acting and filtering in a volute. When the impeller rotates, negative pressure suction is generated in the center of the fan to suck the oil smoke below the range hood into the fan, and the oil smoke is accelerated by the fan and then is collected by the volute and guided to be discharged out of the room.

In order to improve the flow condition of the air inlet of the fan, a current collector is arranged at the air inlet of the volute to rectify the air before entering the impeller; on the other hand, the root of the collector is matched with the impeller, so that the backflow and the vortex flow generated between the impeller and the volute front cover due to the existence of a gap are inhibited. The multi-wing centrifugal fan with the multifunctional flow guide device disclosed in the Chinese patent with the application number of 201110432232.0 comprises the multifunctional flow guide device and a fan main body, wherein the multifunctional flow guide device comprises a flow collector and a flow guider, and is connected with the fan main body in an installing mode through an installing edge on the flow collector, the multifunctional flow guide device has multiple functions of flow collection, rectification, flow guide, condensation and separation of oil smoke, collection of liquid and oil, safety protection and the like, can obviously improve an impeller inlet gas flow field, reduces gas flow loss and flow noise, improves the air volume and the efficiency of the fan, and obtains the maximum air pressure.

In the existing multi-wing centrifugal fan system, after airflow enters the volute from the axial direction, the airflow can flow out from the impeller in the radial direction only by turning a larger angle, so that the turbulence degree of the airflow is increased; the axial air guide surface is close to the front ring of the impeller, and eddy current is easily generated at the position between the axial air guide surface and the front ring of the impeller, so that edge noise is generated (squeaking is generated when the frequency is proper). Moreover, the cooperation between the collector and the impeller presents other problems: when the axial clearance is too small, airflow cannot be quickly converted from axial flow to radial flow after entering the impeller, so that low-speed vortex flow is formed at the front end of the impeller, and the work-doing capacity of the impeller is reduced; when the axial clearance is properly increased, although the airflow entering the impeller can better complete the speed direction conversion, the low-speed vortex flow can be reduced, and the work-doing capability of the front end of the impeller is improved, the leakage flow between the current collector and the impeller is slightly increased, and the work-doing capability of the impeller is also reduced.

Disclosure of Invention

The first technical problem to be solved by the present invention is to provide a centrifugal fan, which can effectively prevent volume loss and ensure air intake, in view of the above-mentioned deficiencies in the prior art.

The second technical problem to be solved by the invention is to provide a range hood with the centrifugal fan.

The technical scheme adopted by the invention for solving the first technical problem is as follows: the utility model provides a centrifugal fan, includes the spiral case, sets up impeller and current collector in the spiral case, be formed with the air intake on the spiral case, current collector sets up in air intake department, impeller and current collector have common axis, current collector includes the annular installation department of being connected with the spiral case and is used for the water conservancy diversion portion of guide air current, the water conservancy diversion portion includes the radial water conservancy diversion portion that inwards extends by the radial inboard of installation department and by the radial inboard of radial water conservancy diversion portion, pass the air intake and to the inside axial water conservancy diversion portion that extends of spiral case, the impeller includes preceding circle, back circle and sets up the blade between preceding circle and back circle, its characterized in that: on the axial section of the collector, the axial flow guide part is a curve gradually expanding towards the radial outside from one end connected with the radial flow guide part towards the direction of the impeller, a concave part is formed at the end part connected with the front ring of each blade, and the concave part is formed by the radial inside of each blade sinking towards the radial outside.

Preferably, in order to facilitate the flow of the air flow, the air flow is sufficiently guided to the impeller, an included angle between tangents of two ends of the axial flow guide part on a section passing through the axis and facing the end part of the impeller is theta, and the value range of the theta is 10-180 degrees.

In order to further reduce the volume loss, one end of the blade facing the air inlet is flush with one end of the axial flow guide part facing the impeller, or one end of the blade facing the air inlet is closer to the air inlet than the other end of the axial flow guide part facing the impeller.

In order to further reduce the volume loss, a flange protruding towards the direction of an air inlet of the volute is arranged on the periphery of the outer side of the front ring of the impeller.

In order to slow down the large vortex caused by wind speed impact, make the airflow adhere to the wall to play the role of combing and noise reduction, and simultaneously prevent the fluctuation of the tail end of the current collector, a bulge is arranged on the inner side of the axial flow guide part.

In order to gradually increase the flow velocity of the air flow and make up for the insufficient negative pressure caused by the concave part arranged on the blade, the width of the bulge in the circumferential direction is gradually increased on the air flow path, so that the shape of the bullet is formed.

Preferably, in order to better guide the air flow, the cross section of the protrusion on the axis is increased along the normal direction of the cross section of the axial flow guide part on the air flow path, and the cross section area of the protrusion on the radial cross section is gradually increased.

To avoid airflow rotation, the ridge line of each protrusion is perpendicular to the mounting portion.

Preferably, the minimum distance between the part of the concave part close to the outlet end of the blade and the outer side of the front ring is more than 3 mm.

The technical scheme adopted by the invention for solving the second technical problem is as follows: a range hood, its characterized in that: a centrifugal fan as described above is applied.

Compared with the prior art, the invention has the advantages that: the concave part is formed on the blade, and the shape gradually expanding outwards towards the blade is formed on the last section of the axial flow guide part of the flow collector, so that airflow can be smoothly guided into the impeller, the wind speed is reasonably adjusted, squeaking sound is avoided, the volume loss of the centrifugal fan is reduced, and the interference between the blade and the flow collector is avoided; the turnup on the front ring can effectively prevent the airflow in the volute from flowing to the inner side of the impeller blade, and the gap between the turnup and the collector is relatively small, so that the flowing resistance is increased, and the volume loss is less likely to occur; the inner side of the axial flow guide part of the current collector is provided with the bulge, so that large vortex caused by wind speed impact is slowed down, airflow adheres to the wall to play a role in combing and noise reduction, and the tail end of the current collector is prevented from fluctuating; through making the arch width crescent in the air current direction for the air current velocity of flow crescent makes up the blade and offers the negative pressure that the depressed part arouses not enough.

Drawings

FIG. 1 is a schematic view of a centrifugal fan according to a first embodiment of the present invention;

FIG. 2 is a sectional view of a centrifugal fan in accordance with a first embodiment of the present invention;

fig. 3 is a schematic view of the collector of a centrifugal fan according to a first embodiment of the invention;

fig. 4 is a cross-sectional view of a collector of a centrifugal fan according to a first embodiment of the present invention;

FIG. 5 is a schematic view of an impeller of a centrifugal fan in accordance with a first embodiment of the present invention;

FIG. 6 is a schematic view of a collector of a centrifugal fan according to a second embodiment of the invention;

fig. 7 is a cross-sectional view of a collector of a centrifugal fan according to a second embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar functions.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present invention and to simplify the description, but are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and that the directional terms are used for purposes of illustration and are not to be construed as limiting, for example, because the disclosed embodiments of the present invention may be oriented in different directions, "lower" is not necessarily limited to a direction opposite to or coincident with the direction of gravity. Furthermore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

Example one

Referring to fig. 1 and 2, a centrifugal fan can be used as a power system in the field of range hood and other requirements. Comprises a volute 1, an impeller 2 arranged in the volute 1 and a motor 3 for driving the impeller 2 to rotate. An air inlet 11 is formed on the volute 1, and a current collector 4 is arranged at the air inlet 11. The volute 1 comprises a front cover plate 12, a rear cover plate 13 and a middle annular wall 14 arranged between the front cover plate 12 and the rear cover plate 13, wherein the air inlet 11 is formed in the front cover plate 12.

Referring to fig. 2 to 4, the collector 4 includes a mounting portion 41 connected to the volute 1 and a flow guide portion 42 for guiding the air flow, and the mounting portion 41 is disposed on an outer side (a side away from the impeller 2) of the volute 1, is annular, and is fixedly connected to an outer periphery of the air inlet 11 of the volute 1. The flow guide portion 42 is hollow and cylindrical, and has a ventilation opening 423 formed in the middle thereof coaxially with the impeller 2 (axis X described below), the flow guide portion 42 includes a radial flow guide portion 421 extending inward from the radially inner side of the mounting portion 41, and an axial flow guide portion 422 extending from the radially inner side of the radial flow guide portion 421 through the air inlet 11 into the scroll casing 1, and the axial flow guide portion 422 extends in the axial direction of the impeller 2 (axis X described below). The axial flow guide part 422 has a curved section in the axial direction of the impeller 2, and the curved section protrudes inward of the axial flow guide part 422 (gradually expands toward the impeller 2), that is, the position at or near the middle in the axial direction is the position with the smallest caliber, the two ends in the axial direction are the positions with the largest caliber, and the end part near the impeller 2 extends outward of the axial flow guide part 422. Preferably, the cross-section is circular. The axial flow guide part 422 with the arc-shaped cross section of the collector 4 can change the direction of the airflow entering the impeller 2, so that the vortex formed at the position when the airflow turns is avoided, and the rectification efficiency is improved. The air flow at the air intake opening 11 is gradually formed by the coanda effect. The axial flow guide part 422 is oriented to the end part of the impeller 2, and the included angle between the tangent lines of the two ends on the section passing through the axis X is theta, and preferably, the value range of theta is 10-180 degrees. The included angle between the tangent line passing through the axial flow guide part 422 and facing the end part of the impeller 2 and the radial direction is 0-90 degrees.

Referring to fig. 2 and 5, the impeller 2 includes a front ring 21, a rear ring 22, and a plurality of blades 23 disposed between the front ring 21 and the rear ring 22. The impeller 2 has an axis X. Each vane 23 is formed with a recessed portion 231 at an end portion connected to the front ring 21, and the recessed portion 231 is formed by recessing the radially inner side of each vane 23 in the radially outer side direction. Alternatively, it is also possible to perform chamfering, that is, chamfering each blade 23 at the end connected to the front ring 21 to form a slope (not shown), the slope extending from the inlet end to the outlet end of the blade 23 in a direction gradually approaching the rear ring 22. When the blade 23 is a straight blade, the inclined plane is a flat plane, and when the blade 23 is an arc blade, the inclined plane is a curved plane.

Since the vanes 23 are generally not able to provide flow near the front ring 21, this portion can be scooped out without affecting the overall air flow and static pressure of the centrifugal fan. After the excavation, while operating without interfering with the collector 4. The minimum distance (the distance between projections on the radial surface of the impeller 2) between the part of the concave part 231 close to the outlet end of the blade 23 and the outer side of the front ring 21 is more than 3mm, so that reasonable operation is ensured, and the air inlet of the centrifugal fan can be optimized.

Compared with the common impeller, the structure of the vane 23 can eliminate the low-speed vortex flow formed at the front end of the impeller. Generally, axial and radial clearances exist between the impeller 2 and the collector 4, which tend to cause backflow of the air flow, and the backflow phenomenon is more serious when the axial clearance increases. With the adoption of the collector 4 with the shape, part of the airflow changes from the axial direction to the speed which is collinear with the tangent line of the end part of the axial flow guiding part 422 of the collector 4 close to the impeller 2 before entering the impeller 2, and the backflow phenomenon is obviously inhibited. In addition, the distance between the impeller 2 and the air inlet 11 can be reasonably reduced when the arc is towards the impeller 2 under the condition that the minimum inlet diameter D0 of the collector 4 is not changed (the gap between the collector 4 and the inner side of the blade 23 of the impeller is reduced), and the volume loss is effectively prevented.

The end of the vane 23 facing the intake port 11 is flush with the end of the axial flow guide 422 facing the impeller 2, or the end of the vane 23 facing the intake port 11 is closer to the axial flow guide 422.

The front ring 21 of the impeller 2 is provided with a flange 211 protruding towards the air inlet 11 of the volute 1 on the outer periphery, and the flange 211 can effectively block the airflow in the volute 1 from flowing to the inner side of the blade 23 of the impeller 2. Meanwhile, the gap between the turned-over edge 211 on the front ring 21 of the impeller 2 and the collector 4 is relatively small, so that the resistance to flow is increased, and the volume loss is less likely to occur. Even if a volume loss occurs, the loss is small, and the lost flow does not affect the inflow but is reintroduced into the impeller 2 due to the structure of the axial flow guide 422 of the collector 4.

Example two

Referring to fig. 6 and 7, in the present embodiment, the difference from the first embodiment is that, inside the axial flow guide portion 422, there are provided at least two protrusions 43 arranged at intervals along the circumferential direction of the axial flow guide portion 422, preferably at even intervals, so as to prevent the air flow from fluctuating at the tail end of the collector 4. Therefore, the resistance on the inner side wall surface of the axial flow guide part 422 is increased, and the large vortex caused by wind speed impact is reduced, so that the sound generated when the airflow passes through is more comfortable, and the airflow entering along the axial flow guide part 422 is better combed.

In the air flow path, the width (size in the circumferential direction) of the projection 43 is gradually increased to form a bullet shape, so that the wind against the wall surface can naturally flow in a streamline shape, and the loss caused by the impact on the projection 43 is avoided. The projections 43 are higher in a section through the axis X in a direction normal to the section of the axial flow guide 422, the projections 43 having a spacing d0 between a radially inner side and a radially outer side, d0 being progressively larger. The cross-sectional area of the radial cross-section is gradually increased to ensure that the air does not bypass the radial cross-section when flowing and diffusing against the wall surface of the current collector 4, so that a large vortex is formed at the position of the air inlet 11. Further, since the width of the protrusion 43 varies as described above, the wind speed against the collector 4 increases from small to large, and the insufficient negative pressure due to the recess 231 close to the blade 23 can be compensated.

To prevent the airflow from rotating, the ridge line of each protrusion 43 is perpendicular to the mounting portion 41.

Claims

1. A centrifugal fan comprises a volute (1), an impeller (2) and a current collector (4) which are arranged in the volute (1), wherein an air inlet (11) is formed in the volute (1), the current collector (4) is arranged at the air inlet (11), the impeller (2) and the current collector (4) have a common axis (X), the current collector (4) comprises an annular mounting part (41) connected with the volute (1) and a flow guide part (42) used for guiding airflow, the flow guide part (42) comprises a radial flow guide part (421) which extends inwards from the radial inner side of the mounting part (41) and an axial flow guide part (422) which extends from the radial inner side of the radial flow guide part (421) to the inside of the volute (1) through the air inlet (11), the impeller (2) comprises a front ring (21), a rear ring (22) and blades (23) which are arranged between the front ring (21) and the rear ring (22), the method is characterized in that: on the axial cross section of the current collector (4), the axial flow guide part (422) is a curve gradually expanding towards the radial outer side from one end connected with the radial flow guide part (421) towards the direction of the impeller (2), a concave part (231) is formed at the end part connected with the front ring (21) of each blade (23), and the concave part (231) is formed by the radial inner side of each blade (23) being concave towards the radial outer side; a projection (43) is arranged on the inner side of the axial flow guide part (422).

2. The centrifugal fan of claim 1, wherein: the axial flow guide part (422) faces to the end part of the impeller (2), and the included angle between tangent lines of two ends on the section passing through the axis (X) is theta, and the value range of the theta is 10-180 degrees.

3. The centrifugal fan according to claim 1 or 2, wherein: the end of the blade (23) facing the air inlet (11) is flush with the end of the axial flow guide part (422) facing the impeller (2), or the end of the blade (23) facing the air inlet (11) is closer to the air inlet (11) than the end of the axial flow guide part (422) facing the impeller (2).

4. The centrifugal fan according to claim 1 or 2, wherein: and a flanging (211) which is convex towards the direction of the air inlet (11) of the volute (1) is arranged on the outer side periphery of the front ring (21) of the impeller (2).

5. The centrifugal fan according to claim 1 or 2, wherein: the width of the projection (43) in the circumferential direction is gradually increased in the air flow path, thereby forming the shape of a bullet head.

6. The centrifugal fan of claim 5, wherein: on the air flow path, the cross section of the bulge (43) on the passing axis (X) is increased along the normal direction of the cross section of the axial flow guide part (422), and the cross section area of the bulge (43) on the radial cross section is gradually increased.

7. The centrifugal fan of claim 5, wherein: the ridge line of each protrusion (43) is perpendicular to the mounting portion (41).

8. The centrifugal fan according to claim 1 or 2, wherein: the minimum distance between the part of the concave part (231) close to the outlet end of the blade (23) and the outer side of the front ring (21) is more than 3 mm.

9. A range hood, its characterized in that: use of a centrifugal fan according to any of claims 1 to 8.