A centrifugal fan, a range hood using the centrifugal fan, and a control method

Abstract

The present invention discloses a centrifugal fan, including a volute, wherein the volute includes an annular wall, an outlet and a volute tongue, and is characterized in that a vortex generator is provided on the annular wall, located at the rear section of the volute profile and close to the outlet of the volute. Also disclosed is a range hood using the centrifugal fan, and a control method for the range hood. By providing a vortex generator at the rear section of the volute profile, the flow separation phenomenon at the fan outlet is improved, thereby reducing aerodynamic noise; and the height of the vortex generator can be automatically adjusted according to the flow rate of the airflow under different working conditions to adapt to different boundary layer thicknesses of the volute wall, thereby ensuring that a better rectification and noise reduction effect can be achieved under different working conditions, thereby improving the performance of the range hood.

Description

Technical Field

[0001] The invention relates to kitchen equipment, in particular to a centrifugal fan, a range hood using the centrifugal fan, and a control method of the range hood. Background Art

[0002] The working principle of the centrifugal fan is that the motor drives the impeller to rotate to do work on the airflow, and the air is discharged radially through the expansion effect of the volute. Due to different smoke exhaust environments, household range hoods will operate under corresponding working conditions according to the resistance of the outlet flue. Figure 20 to Figure 23 According to the working conditions of the standard air performance test bench for range hoods, four typical working conditions are selected from large resistance to small resistance for fluid simulation, and the pressure distribution cloud diagram in the fan and the air outlet section under typical working conditions is obtained. It can be seen from the figure that under the four working conditions, due to the influence of the fan structure and the outlet environment, obvious flow separation and strong pressure pulsation will occur near the fan outlet, which will cause energy loss and strong aerodynamic noise.

[0003] In order to improve the flow state of airflow entering the fan and reduce gas flow loss and flow noise, noise reduction devices are usually installed at the inlet and outlet of the fan. For example, a noise reduction volute disclosed in Chinese patent application number 201720526157.7 includes a volute enclosure, a side panel, a first sound absorbing component, a second sound absorbing component, an air guide ring and an outlet mounting plate. The side panels are arranged on both sides of the volute enclosure. The tops of the volute enclosure and the side panels form an air outlet. An air inlet is provided on the side panel. The air guide ring is arranged on one side of the volute enclosure and is located on the outside of the side panel. The first sound absorbing component is arranged on either side of the volute enclosure and is located between the side panel and the volute enclosure. The second sound absorbing component is arranged between the air guide ring and the side panel. For example, the applicant's application number is 2016101. Chinese Patent No. 11243.1 discloses a fan volute for a range hood, comprising a volute tongue, the volute tongue comprising a volute tongue inner wall, the volute tongue forming a closed cavity, at least one longitudinal partition is arranged in the cavity along the axial direction of the volute, and a plurality of radial partitions are arranged along the axial direction perpendicular to the volute, the longitudinal partitions and the radial partitions divide the cavity into a plurality of independent closed silencing cavities, a hole is opened on the volute tongue inner wall portion corresponding to each silencing cavity, and by dividing the cavity in the volute tongue into a plurality of independent closed small cavities, the air column in the cavity rubs against the cavity inner wall to consume sound energy, thereby absorbing and reducing noise.

[0004] The above-mentioned noise reduction devices arranged at the inlet or outlet of the fan do not significantly improve the internal flow field characteristics of the fan, and therefore need to be further improved. Summary of the invention

[0005] The first technical problem to be solved by the present invention is to provide a centrifugal fan that can achieve better rectification and noise reduction effects under different working conditions in response to the problems existing in the above-mentioned prior art.

[0006] The second technical problem to be solved by the present invention is to provide a range hood using the centrifugal fan.

[0007] The third technical problem to be solved by the present invention is to provide a control method for the above range hood.

[0008] The technical solution adopted by the present invention to solve the above-mentioned first technical problem is: a centrifugal fan, including a volute, the volute including an annular wall, an outlet and a volute tongue, characterized in that a vortex generator is arranged on the annular wall, located at the rear section of the volute profile and close to the outlet of the volute.

[0009] Preferably, the profile of the volute is an involute spiral, the starting point of the profile of the volute is close to the volute tongue, and the rear section of the profile of the volute is at 240° to 300° of the spiral.

[0010] Preferably, to facilitate the adjustment of the height of the vortex generator, the vortex generator includes a push rod motor, outer blades and inner blades. The push rod motor is fixed on the outer side of the annular wall of the volute, and the output shaft of the push rod motor extends into the inner side of the annular wall. The outer blades and the inner blades are located on the inner side of the annular wall. The inner blades are arranged inside the outer blades and connected to the output shaft of the push rod motor, so that the inner blades can make a linear motion relative to the outer blades towards or away from the annular wall.

[0011] Preferably, in order to minimize aerodynamic noise caused by disturbance, the outer blades and the inner blades are both in an airfoil shape.

[0012] The technical solution adopted by the present invention to solve the above-mentioned second technical problem is: a range hood using the centrifugal fan as described above, wherein a working condition detection device for detecting the working condition of the range hood is arranged inside the range hood, and the working condition detection device is electrically connected to the vortex generator, so that the corresponding action of the vortex generator can be controlled according to different detected working conditions.

[0013] According to one aspect of the present invention, an air outlet hood is provided at the outlet of the centrifugal fan, an outlet pipe is provided on the top of the air outlet hood, the operating condition detection device is a flow velocity measuring device provided on the outlet pipe, the flow velocity measuring device includes a Pitot tube provided on the inner side of the peripheral wall of the outlet pipe, and a feedback unit which processes the flow velocity information measured by the Pitot tube and feeds it back to the vortex generator to control the action of the vortex generator.

[0014] According to another aspect of the present invention, an air outlet hood is provided at the outlet of the centrifugal fan, an outlet pipe is provided on the top of the air outlet hood, the operating condition detection device is a flow rate measuring device provided on the outlet pipe, the flow rate measuring device includes a static pressure tube provided on the inner side of the peripheral wall of the outlet pipe, and a feedback unit which processes the flow rate information measured by the Pitot tube and feeds it back to the vortex generator to control the action of the vortex generator.

[0015] In order to make the airflow at the Pitot tube or static pressure tube uniform and the measurement more accurate, the flow velocity measuring device also includes a rectifying grid arranged in the outlet pipe. On the oil fume flow path, the Pitot tube or static pressure tube is located downstream of the rectifying grid.

[0016] According to another aspect of the present invention, the centrifugal fan also includes an impeller and a motor for driving the impeller, and the operating condition detection device is a power detection module, which includes a power detection unit arranged on the bus bar of the motor and used to detect the power of the motor, and a feedback unit that processes the power information measured by the power detection unit and feeds it back to the vortex generator to control the action of the vortex generator.

[0017] According to another aspect of the present invention, the centrifugal fan also includes an impeller, and the operating condition detection device is a speed measurement module, which includes a speed measurement unit for detecting the speed of the impeller, and a feedback unit for processing the speed information measured by the speed measurement unit and feeding it back to the vortex generator to control the action of the vortex generator.

[0018] The technical solution adopted by the present invention to solve the third technical problem is: a control method of the range hood as described above, comprising the following steps:

[0019] 1) Calibration: Calibrate the data detected by the working condition detection device obtained under experimental conditions, and write the corresponding relationship between the calibrated data representing the working condition and the height of the eddy current generator into the feedback unit of the working condition detection device;

[0020] 2) Flow rate measurement: When the current working condition of the range hood changes, the current data detected by the working condition detection device is processed by the feedback unit;

[0021] 3) Adjusting the height of the vortex generator: The feedback unit obtains the corresponding relationship between the pre-stored calibrated data and the height of the vortex generator, determines the working condition corresponding to the current data and the height to which the vortex generator needs to be adjusted under this working condition, and drives the inner blade to move through the push rod motor.

[0022] Compared with the prior art, the advantages of the present invention are: by arranging a vortex generator at the rear section of the volute profile, the flow separation phenomenon at the fan outlet is improved, thereby reducing aerodynamic noise; and the height of the vortex generator can be automatically adjusted according to the flow rate of the airflow under different working conditions to adapt to the different volute wall boundary layer thicknesses, thereby ensuring that a better rectification and noise reduction effect can be achieved under different working conditions, thereby improving the performance of the range hood. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of a first embodiment of a range hood of the present invention;

[0024] Figure 2 is a cross-sectional view of a first embodiment of a range hood of the present invention;

[0025] Figure 3 A schematic diagram of a centrifugal fan of a range hood according to a first embodiment of the present invention;

[0026] Figure 4 is a cross-sectional view of a centrifugal fan of a range hood according to a first embodiment of the present invention;

[0027] Figure 5 A schematic diagram of a vortex generator of a centrifugal fan of a range hood according to a first embodiment of the present invention;

[0028] Figure 6 A cross-sectional view of a vortex generator of a centrifugal fan of a range hood according to a first embodiment of the present invention;

[0029] Figure 7 is a schematic diagram of an outlet duct of a first embodiment of a range hood of the present invention;

[0030] Figure 8 is a cross-sectional view of an outlet duct of a first embodiment of a range hood of the present invention;

[0031] Fig. 9 for Figure 8 A schematic diagram of the partial enlargement of Ⅰ;

[0032] Fig.10 is a control flow chart of a first embodiment of the range hood of the present invention;

[0033] Figure 11-1 A schematic diagram of a state A of a vortex generator of a centrifugal fan of a range hood according to a first embodiment of the present invention;

[0034] Figure 11-2 It is a schematic diagram of a state B of a vortex generator of a centrifugal fan of a range hood according to a first embodiment of the present invention;

[0035] Figure 11-3It is a schematic diagram of a state C of a vortex generator of a centrifugal fan of a range hood according to a first embodiment of the present invention;

[0036] Figure 11-4 It is a schematic diagram of a state D of a vortex generator of a centrifugal fan of a range hood according to a first embodiment of the present invention;

[0037] Fig.12 is a schematic diagram of an outlet duct of a second embodiment of a range hood of the present invention;

[0038] Fig.13 is a cross-sectional view of an outlet duct of a second embodiment of a range hood of the present invention;

[0039] Fig.14 for Fig.13 A partial II enlarged schematic diagram of

[0040] Fig.15 is a control flow chart of a second embodiment of the range hood of the present invention;

[0041] Fig.16 is a schematic diagram of a centrifugal fan of a range hood according to a third embodiment of the present invention;

[0042] Fig.17 is a control flow chart of a third embodiment of the range hood of the present invention;

[0043] Fig.18 is a cross-sectional view of a fourth embodiment of a range hood of the present invention;

[0044] Fig.19 is a control flow chart of a fourth embodiment of the range hood of the present invention;

[0045] Fig. 20 It is a pressure cloud diagram of the No. 3 orifice plate of the range hood in the prior art;

[0046] Fig.21 It is a pressure cloud diagram of the No. 5 orifice plate of the range hood in the prior art;

[0047] Fig. 22 It is a pressure cloud diagram of the No. 7 orifice plate of the range hood in the prior art;

[0048] Fig.23 It is a pressure cloud diagram of the No. 9 orifice plate of the range hood in the prior art. DETAILED DESCRIPTION

[0049] The present invention is further described in detail below with reference to the accompanying drawings.

[0050] Embodiment 1

[0051] See also Figure 1 to Figure 4A range hood includes a fume hood 1, a chassis 2 disposed above the fume hood 1, and a centrifugal fan 3 disposed in the chassis 2. An air outlet hood 4 is disposed at the outlet of the centrifugal fan 3, and an outlet pipe 5 is disposed on the top of the air outlet hood 4, and the two are interconnected. An air inlet 11 is provided on the fume hood 1. Thus, under the action of the centrifugal fan 3, oil smoke is sucked into the range hood from the bottom through the air inlet 11, and discharged to a common flue through the air outlet hood 4 and the outlet pipe 5.

[0052] The centrifugal fan 3 includes a volute 31, an impeller 32 disposed in the volute 31, a front air guide plate 35, and a rear air guide plate 36. The volute 31 includes an annular wall 311, a front end of the annular wall 311 is fixed to the front air guide plate 35, and a rear end of the annular wall 311 is fixed to the rear air guide plate 36. The annular wall 311, the front air guide plate 35, and the rear air guide plate 36 further define an outlet 312 of the volute 31. The volute 31 also has a volute tongue 313.

[0053] A vortex generator 33 is provided at the rear section of the annular wall 311, near the outlet 312 of the volute 31. In this embodiment, there are a plurality of vortex generators 33, which are arranged at intervals from the position near the front air guide plate 35 to the position near the rear air guide plate 36. The profile of the annular wall 311 is an involute spiral line, and the vortex generator 33 is provided at the rear section of the profile of the annular wall 311. The starting point of the profile of the annular wall 311 is close to the volute tongue 313, and the rear section of the profile refers to 240° to 300° of the spiral line.

[0054] See also Figure 5 and Figure 6 The vortex generator 33 includes a push rod motor 331, an outer blade 332 and an inner blade 333. The push rod motor 331 is preferably a servo motor, which is fixed on the outer side of the annular wall 311 of the volute 31, and the output shaft 3311 of the push rod motor 331 extends into the inner side of the annular wall 311. The outer blade 332 and the inner blade 333 are located on the inner side of the annular wall 311, wherein the inner blade 332 is arranged inside the outer blade 332 and connected to the output shaft 3311 of the push rod motor 331. Thus, the push rod motor 331 can push the inner blade 333 to move closer to or away from the annular wall 311 relative to the outer blade 332. The outer blade 332 and the inner blade 333 are metal blades in the shape of an airfoil, which can be rectangular, elliptical, trapezoidal, etc.

[0055] Since the fluid has viscosity, when it flows along the wall, a boundary layer will be formed near the wall due to the resistance of the wall surface. The calculation formula of the boundary layer thickness is as follows:

[0056]

[0057] Re = ρvx / μ;

[0058] Among them, δ is the boundary layer thickness, Re is the Reynolds number, v is the fluid velocity, μ is the dynamic viscosity, and x is the coordinate. It can be seen that the greater the flow velocity, the greater the Reynolds number, and the smaller the boundary layer thickness.

[0059] The vortex generator 33 is often used to delay the occurrence of flow separation on the lower surface at a large angle of attack, and the installation direction is along the airflow direction. The principle of the vortex generator 33 is: an airfoil-shaped blade device is set on the wall surface through which the fluid flows. When the airflow flows through the blade, a series of shedding vortices are generated at the rear. These shedding vortices can enhance the turbulent kinetic energy of the downstream boundary layer, making it difficult for the downstream fluid to flow separate from the wall. The height of the vortex generator 33 (the overall height of the inner blades 333 and the outer blades 332 relative to the annular wall 311 of the volute 31) is related to the thickness of the boundary layer, which is generally about half the thickness of the boundary layer. The height of the vortex generator 33 of the present application can be adjusted within the range of 2mm to 20mm, preferably, 3mm to 6mm.

[0060] The vortex generator 33 used in the present application has an airfoil shape, which can minimize the aerodynamic noise caused by disturbance. Moreover, since the height of the vortex generator 33 is only at the millimeter level, the disturbance generated basically stays in the boundary layer, and the noise generated will not affect the overall noise of the range hood.

[0061] In order to automatically adjust the height of the vortex generator 33, a working condition detection device is provided inside the range hood and is electrically connected to the push rod motor 331 of the vortex generator 33. Figure 2 , Figure 7 to Figure 9 The working condition detection device is a flow rate measuring device arranged on the outlet pipe 5, including a rectifying grid 61 arranged in the outlet pipe 5, a pitot tube 62 arranged on the inner side of the peripheral wall of the outlet pipe 5 and a feedback unit 63 on the outer side of the peripheral wall of the outlet pipe 5. On the oil smoke flow path, the pitot tube 62 is located downstream of the rectifying grid 61. The feedback unit 63 includes a scale adjustment loop 631, an operational amplifier 632 and a main controller 63. The main controller 63 is electrically connected to the push rod motor 331 of the vortex generator 33. The rectifying grid 61 allows the airflow to be rectified by the rectifying grid 61 after entering the outlet pipe 5, so that the airflow near the pitot tube 62 is uniform and the measurement is more accurate. The pitot tube 62 adopts the existing technology, and a static pressure measuring hole 621 for measuring the static pressure Ps is opened on its outer peripheral wall, and a total pressure measuring hole 622 for measuring the total pressure Pt is opened at the bottom. According to the formula:

[0062]

[0063] Where ρ is the smoke density, from which the flow velocity v flowing through the pitot tube 62 can be obtained. The flow velocity information is processed and fed back to the vortex generator 33 through the feedback unit 63 connected to the pitot tube 62, and then the inner blade 333 is driven by the push rod motor 331 to adjust the height of the vortex generator 33, thereby having a better inhibitory effect on the flow separation phenomenon and aerodynamic noise under different working conditions and improving the fan performance.

[0064] For a specific model, the air performance test is first carried out in the laboratory to measure the PQ curve, and the flow rate value corresponding to the orifice plate working condition is obtained by flow conversion, and written into the feedback unit 63 after calibration, so that the feedback unit 63 is controlled according to the calibration value (including the data corresponding to the flow rate v and the height of the vortex generator 33). The calculation formula of the boundary layer thickness is as described above. According to the flow rate v, the thickness of the boundary layer on the surface of the volute 31 can be roughly estimated, so that the height of the vortex generator 33 is adjusted to the corresponding value. The height of the vortex generator 33 is generally between 0.5 and 1 of the boundary layer thickness.

[0065] An example of a control method for a particular model of range hood, such as Fig.10 The process shown includes the following steps:

[0066] 1) Calibration: After the flow velocity obtained from the experiment is calibrated, the corresponding relationship between each calibrated flow velocity and the height of the vortex generator 33 is written into the feedback unit 63;

[0067] 2) Measuring flow rate: When the current ambient airflow changes during the operation of the range hood, the pitot tube 62 measures the current flow rate v (in m / s), which is processed by the feedback unit 63, including the flow rate v and the scale adjustment loop 631 (such as a potentiometer) as two inputs of the operational amplifier 632, and the output of the operational amplifier 632 is transmitted to the main controller 633;

[0068] 3) Adjusting the height of the vortex generator 33: The main controller 633 reads the pre-stored correspondence with the height of the vortex generator 33 according to the measured flow velocity v, determines the corresponding working condition and the height to which the vortex generator 33 needs to be adjusted under this working condition, and drives the inner blade 333 to move through the push rod motor 331: If v∈(0,5] (indicating the working condition of orifice plate No. 3 and greater resistance), the height of the vortex generator 33 is adjusted to 6mm (state A, Figure 11-1 ); if v∈(5,8] (indicates the working condition between orifice plate No. 3 and orifice plate No. 5), the height of the vortex generator 33 is adjusted to 5 mm (state B, Figure 11-2 ); if v∈(8,13.5] (indicating the working condition between orifice plate No. 5 and orifice plate No. 7), the height of the vortex generator 33 is adjusted to 4 mm (state C, Figure 11-3); if v∈(13.5,16] (indicating the working condition between orifice plate No. 7 and orifice plate No. 9), the height of the vortex generator 33 is adjusted to 3 mm (state D, Figure 11-4 ). The greater the flow velocity v, the smaller the height of the vortex generator 33.

[0069] Embodiment 2

[0070] See also Figure 12 to Figure 14 In this embodiment, the difference from the first embodiment is that the working condition detection device is a static pressure measuring device arranged on the outlet pipe 5, including a rectifying grid 61 arranged in the outlet pipe 5, a static pressure pipe 62' arranged on the inner side of the peripheral wall of the outlet pipe 5, and a feedback unit 63 on the outer side of the peripheral wall of the outlet pipe 5. In the oil fume flow path, the static pressure pipe 62' is located downstream of the rectifying grid 61. The rectifying grid 61 allows the airflow to be rectified by the rectifying grid 61 after entering the outlet pipe 5, so that the airflow near the static pressure pipe 62' is uniform and the measurement is more accurate. The static pressure pipe 62' adopts the existing technology, and a static pressure measuring hole 621' for measuring the static pressure Ps is opened on its outer peripheral wall. After the static pressure is measured, the feedback unit 63 processes the flow velocity information and feeds it back to the vortex generator 33.

[0071] For control methods, see Fig.15 , which is different from the first embodiment in that a static pressure tube 62' is used to detect the flow velocity v.

[0072] Embodiment 3

[0073] See also Fig.16 In this embodiment, the difference from the above-mentioned embodiment 1 is that the operating condition detection device is a power detection module 7, which is arranged on the bus 341 of the motor 34 of the centrifugal fan 3 for driving the impeller 32, and includes a power detection unit 71 and a feedback unit. The detection unit 71 is used to detect the power of the motor 34. The function of the feedback unit is the same as that of the embodiment 1. The measured power information is processed and fed back to the vortex generator 33, and then the height of the blades of the vortex generator 33 is adjusted by the push rod motor 331.

[0074] For a specific model, air performance tests are first carried out in the laboratory to measure the PQ curve, and the flow rate value corresponding to the orifice plate is obtained through flow conversion. After calibration, it is written into the feedback unit, and the feedback unit is controlled according to the calibration value (including data corresponding to the power and the height of the vortex generator 33).

[0075] An example of a control method for a particular model of range hood, such as Fig.17 The process shown includes the following steps:

[0076] 1) Calibration: After the power obtained from the experiment is calibrated, the corresponding relationship between each calibrated power and the height of the vortex generator 33 is written into the feedback unit;

[0077] 2) Power measurement: When the operating conditions of the range hood change during operation, the power detection unit 71 measures the power P (unit W) of the motor 34, which is processed by the feedback unit, including the power of the motor 34 and the scale adjustment loop 631 (such as a potentiometer) as two inputs of the operational amplifier 632, and the output of the operational amplifier 632 is transmitted to the main controller 633;

[0078] 3) Adjusting the height of the vortex generator 33: The main controller 633 reads the pre-stored correspondence with the height of the vortex generator 33 according to the measured power of the motor 34, determines the corresponding working condition and the height to which the vortex generator 33 needs to be adjusted under this working condition, and drives the inner blade 333 to move through the push rod motor 331: when P∈[145,155)(indicating the working condition of orifice plate No. 3 and greater resistance), the height of the vortex generator is adjusted to 6mm (state A); when P∈[155,185)(indicating the working condition between orifice plate No. 3 and orifice plate No. 5), the height of the vortex generator is adjusted to 5mm (state B); when P∈[185,225)(indicating the working condition between orifice plate No. 5 and orifice plate No. 7), the height of the vortex generator is adjusted to 4mm (state C); when P∈[225,260)(indicating the working condition between orifice plate No. 7 and orifice plate No. 9), the height of the vortex generator is adjusted to 3mm (state D). The greater the power P, the smaller the height of the vortex generator 33 .

[0079] Embodiment 4

[0080] See also Fig.18 In this embodiment, the difference from the first embodiment is that the working condition detection device is a speed measurement module, including a speed measurement unit 81 and a feedback unit. The speed measurement unit 81 is used to detect the speed of the impeller 32, including a reflector 811 and a laser emitting and receiving device 812, wherein the reflector 81 is arranged on the middle plate 321 of the impeller 32, and the laser emitting and receiving device 82 is arranged in the front side of the chassis 2. The function of the feedback unit is the same as that of the first embodiment, and the measured speed information is processed and fed back to the vortex generator 33, and then the height of the blades of the vortex generator 33 is adjusted by the push rod motor 331.

[0081] For a specific model, the air performance test is first carried out in the laboratory to measure the PQ curve and the speed corresponding to the orifice working condition, and then write them into the feedback unit after calibration. In the feedback unit, the feedback unit is controlled according to the calibration value (including the data corresponding to the speed and the height of the vortex generator 33).

[0082] According to the control example of a specific model of range hood, such as Fig.19 As shown, the following steps are included:

[0083] 1) Calibration: After the rotation speed (unit: rms) obtained from the experiment is calibrated, the corresponding relationship between each calibrated rotation speed and the height of the vortex generator 33 is written into the feedback unit;

[0084] 2) Measuring flow rate: When the current working condition of the range hood changes during operation, the speed measuring unit 81 measures the current speed R, which is processed by the feedback unit, including the speed of the impeller 32 and the scale adjustment loop 631 (such as a potentiometer) as two inputs of the operational amplifier 632, and the output of the operational amplifier 632 is transmitted to the main controller 633;

[0085] 3) Adjusting the height of the vortex generator 33: The main controller 633 reads the pre-stored correspondence with the height of the vortex generator 33 according to the measured rotation speed R, determines the corresponding working condition and the height to which the vortex generator 33 needs to be adjusted under this working condition, and drives the inner blade 333 to move through the push rod motor 331: when R∈[1400,1450)(indicating the working condition of orifice plate No. 3 and greater resistance), the height of the vortex generator is adjusted to 6mm (state A); when R∈[1350,1400)(indicating the working condition between orifice plate No. 3 and orifice plate No. 5), the height of the vortex generator is adjusted to 5mm (state B); when R∈[1250,1350)(indicating the working condition between orifice plate No. 5 and orifice plate No. 7), the height of the vortex generator is adjusted to 4mm (state C); when R∈[1100,1250)(indicating the working condition between orifice plate No. 7 and orifice plate No. 9), the height of the vortex generator is adjusted to 3mm (state D). The smaller the rotation speed R is, the smaller the height of the vortex generator 33 is.

Claims

1. A centrifugal fan, comprising a volute (31), wherein the volute (31) comprises an annular wall (311), an outlet (312) and a volute tongue (313), characterized in that: A vortex generator (33) is provided on the annular wall (311) at a rear section of the profile of the volute (31) and close to an outlet (312) of the volute (31); the profile of the volute (31) is an involute spiral; the starting point of the profile of the volute (31) is close to the volute tongue (313); and the rear section of the profile of the volute (31) is at 240° to 300° of the spiral; The vortex generator (33) comprises a push rod motor (331), an outer blade (332) and an inner blade (333); the push rod motor (331) is fixed on the outer side of the annular wall (311) of the volute (31); the output shaft (3311) of the push rod motor (331) extends into the inner side of the annular wall (311); the outer blade (332) and the inner blade (333) are located on the inner side of the annular wall (311); the inner blade (333) is arranged inside the outer blade (332) and connected to the output shaft (3311) of the push rod motor (331), so that the inner blade (333) can make a linear motion relative to the outer blade (332) to approach or move away from the annular wall (311).

2. The centrifugal fan according to claim 1, characterized in that: The outer blades (332) and the inner blades (333) are both in an airfoil shape.

3. A range hood using the centrifugal fan as claimed in claim 1 or 2, wherein a working condition detection device for detecting the working condition of the range hood is arranged inside the range hood, and the working condition detection device is electrically connected to the vortex generator (33), so that the corresponding action of the vortex generator (33) can be controlled according to different detected working conditions.

4. The range hood according to claim 3, characterized in that: An air outlet hood (4) is provided at the outlet of the centrifugal fan, an outlet pipe (5) is provided at the top of the air outlet hood (4), the operating condition detection device is a flow rate measuring device provided on the outlet pipe (5), the flow rate measuring device comprises a Pitot tube (62) provided on the inner side of the peripheral wall of the outlet pipe (5), and a feedback unit (63) for processing flow rate information measured by the Pitot tube (62) and feeding it back to the vortex generator (33) so as to control the operation of the vortex generator (33).

5. The range hood according to claim 3, characterized in that: An air outlet hood (4) is provided at the outlet of the centrifugal fan, an outlet pipe (5) is provided at the top of the air outlet hood (4), the operating condition detection device is a flow rate measuring device provided on the outlet pipe (5), the flow rate measuring device comprises a static pressure tube (62') provided on the inner side of the peripheral wall of the outlet pipe (5), and a feedback unit (63) for processing the flow rate information measured by the pitot tube (62) and feeding it back to the vortex generator (33) so as to control the action of the vortex generator (33).

6. The range hood according to claim 4 or 5, characterized in that: The flow rate measuring device further comprises a rectifying grid (61) arranged in the outlet pipe (5), and the Pitot tube (62) or the static pressure tube (62') is located downstream of the rectifying grid (61) on the oil smoke flow path.

7. The range hood according to claim 3, characterized in that: The centrifugal fan further comprises an impeller (32) and a motor (34) for driving the impeller (32); the operating condition detection device is a power detection module (7); the power detection module (7) comprises a power detection unit (71) arranged on a busbar (341) of the motor (34) and used to detect the power of the motor (34); and a feedback unit for processing power information measured by the power detection unit (71) and feeding it back to the vortex generator (33) to control the operation of the vortex generator (33).

8. The range hood according to claim 3, characterized in that: The centrifugal fan further comprises an impeller (32), the operating condition detection device is a speed measurement module (8), and the speed measurement module (8) comprises a speed measurement unit (81) for detecting the speed of the impeller (32), and a feedback unit for processing the speed information measured by the speed measurement unit (81) and feeding it back to the vortex generator (33) to control the operation of the vortex generator (33).

9. A method for controlling a range hood according to any one of claims 3 to 8, comprising the following steps: 1) Calibration: calibrating the data detected by the working condition detection device obtained under experimental conditions, and writing the corresponding relationship between the calibrated data representing the working condition and the height of the vortex generator (33) into the feedback unit (63) of the working condition detection device; 2) Measuring flow rate: when the current working condition of the range hood changes during operation, the current data detected by the working condition detection device is processed by the feedback unit (63); 3) Adjusting the height of the vortex generator (33): The feedback unit (63) reads the corresponding relationship between the pre-stored calibrated data and the height of the vortex generator (33), determines the working condition corresponding to the current data and the height to which the vortex generator (33) needs to be adjusted under this working condition, and drives the inner blade (333) to move through the push rod motor (331).

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