Centrifugal fan, fan system and range hood using the fan system

Abstract

The present invention relates to a centrifugal fan, a fan system and a range hood using the fan system. The centrifugal fan comprises: a volute and an impeller arranged in the volute, wherein the air outlet of the volute is provided with a guide surface for guiding the airflow inside the volute to the air outlet; a rectifier plate arranged in the volute and adjacent to the air outlet, and located on the side of the guide surface facing the impeller, wherein the rectifier plate separates the flow channel of the volute at the air outlet into a first flow channel close to the impeller and a second flow channel away from the impeller. The low-energy fluid area and the recirculation area at the air outlet are reduced, the high-pressure area at the outlet turn of the centrifugal fan is dispersed, and a passive "pressure relief" treatment is performed on it, the pressure gradient and velocity gradient at the turn are reduced, and the high-pressure airflow is prevented from diffusing from the outlet turn to the impeller area due to the increase of the flue resistance, so that the impeller cuts the high-pressure airflow and generates the possibility of noise, thereby eliminating the "puff" return air abnormal sound under the condition of large resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of centrifugal fans, and in particular to a centrifugal fan, a fan system and a range hood using the fan system. Background Art

[0002] Centrifugal fans are a common air supply device, commonly used in products such as range hoods and air conditioners. Centrifugal fans usually include a volute, an impeller installed in the volute, and a motor that drives the impeller to rotate. When the impeller rotates, negative pressure suction is generated in the center of the fan, sucking the oil smoke under the range hood into the fan, which is then accelerated by the fan and collected by the volute and guided to be discharged outdoors.

[0003] For thin range hoods, the fan system generally adopts a horizontal fan with a top-outlet air outlet. For example, the Chinese invention patent application with application number CN202011091494.0 (authorization announcement number: CN112377462B) discloses a centrifugal fan, including a volute, an impeller arranged in the volute, and a guide device, wherein the volute is provided with an air inlet and an air outlet, the direction of the air outlet is parallel to the axial direction of the impeller, the guide device is arranged in the volute and corresponds to the air outlet, so as to guide the radial air outlet of the impeller to the air outlet, wherein the guide surface of the guide device is composed of three curves to form a curved surface, which can effectively guide the airflow to turn, reduce the turning energy loss and aerodynamic noise.

[0004] For this type of top-out horizontal centrifugal fan, under some working conditions, due to factors such as the installation of the range hood's external exhaust pipe and environmental issues, the flue resistance is very large. When the resistance reaches a certain value, the range hood will produce a "puff" return air abnormal sound, which seriously affects the sound quality of the whole machine and makes the user experience worse. The usual way to deal with this phenomenon is to check the blockage of the user's external exhaust pipe and clear it, but this method does not fundamentally solve the abnormal sound problem. Through experiments, the applicant found that the reason why the range hood produces a "puff" return air abnormal sound is that there is an obvious and large-scale low-energy fluid zone and recirculation zone at the outlet of the top-out horizontal fan, which seriously affects the gas flow at the outlet, causing the airflow to accumulate and swirl at the outlet, and further causing the pressure at the back of the fan system (that is, the turning point) to rise sharply. In addition, due to the existence of the flue resistance, the high-pressure area will spread to the impeller area, and the high-speed rotating impeller cutting the high-pressure airflow will produce airflow noise.

[0005] In addition, for the dual fan system in the above patent application, Figure 1 As shown, when only one side of the motor is running, the outlet airflow will flow back to the other side (specifically the side where the motor is not running) under the combined action of the outlet low-energy fluid, the swirling airflow and the flue resistance, and then be discharged from the air inlet on the other side, affecting the oil fume extraction effect and the user's intuitive experience.

[0006] Therefore, the existing centrifugal fans need to be further improved. Summary of the invention

[0007] The first technical problem to be solved by the present invention is to provide a centrifugal fan which can effectively improve the problem of abnormal return air noise under high resistance conditions in view of the current status of the prior art.

[0008] The second technical problem to be solved by the present invention is to provide a fan system that can effectively improve the problem of abnormal return air noise under high resistance conditions in view of the current status of the prior art.

[0009] The third technical problem to be solved by the present invention is to provide a range hood using the above-mentioned fan system in view of the current status of the prior art.

[0010] The technical solution adopted by the present invention to solve the above-mentioned first technical problem is: a centrifugal fan, comprising:

[0011] A volute and an impeller disposed in the volute, wherein the volute has an air outlet, the air outlet direction of the volute air outlet is parallel to the axial direction of the impeller, and the air outlet of the volute has a guide surface for guiding the airflow inside the volute to the air outlet;

[0012] A rectifying plate is arranged in the volute, adjacent to the air outlet, and located on the side of the guide surface facing the impeller. The rectifying plate separates the flow channel of the volute at the air outlet into a first flow channel close to the impeller and a second flow channel away from the impeller.

[0013] The above-mentioned guide surface can be formed by the bending change of the cover plate or the annular wall of the volute itself, or it can be formed by adding a corresponding guide component in the volute. Preferably, in order to facilitate processing and reduce processing costs, the volute includes a first cover plate, a second cover plate and an annular wall connected between the first cover plate and the second cover plate, the first cover plate is provided with the above-mentioned air inlet, the second cover plate is provided with the above-mentioned air outlet, and a guide plate is provided between the first cover plate and the second cover plate adjacent to the air outlet, which is inclined from the first cover plate to the position of the air outlet of the second cover plate in the direction away from the impeller. The side wall surface of the guide plate facing the impeller is the guide surface, and the rectifying plate is an arc-shaped plate with a substantially consistent inclination direction with the guide plate.

[0014] In order to solve the problem of oil smoke backflow, the rectifier plate has a first side away from the air outlet and a second side adjacent to the air outlet. The rectifier plate is also provided with a first check valve plate and a second check valve plate. The first check valve plate is rotatably connected to the first side of the rectifier plate and can open or close the first flow channel. The second check valve plate is rotatably connected to the second side wall of the rectifier plate and can open or close the second flow channel. Since the first check valve plate and the second check valve plate are respectively connected to two relatively distant side positions of the rectifier plate, the interference problem between the two check valve plates when they are opened is avoided, and there is no influence between the two, thereby ensuring the stability of the air outlet when the first flow channel and the second flow channel are opened.

[0015] In order to ensure that the addition of the check valve plate will not affect the flow guiding effect of the rectifier plate, the first check valve plate is linked with the second check valve plate, so as to have a first state of synchronously opening the corresponding first flow channel and the second flow channel and a second state of synchronously closing the corresponding first flow channel and the second flow channel:

[0016] In the first state, the first check valve plate covers the wall surface of the rectifying plate facing the impeller, and the second check valve plate is connected to the area where the second side edge of the rectifying plate is located and extends along the airflow direction there, so that the first check valve plate, the rectifying plate and the second check valve plate form a complete rectifying plate structure;

[0017] In the second state, the first check valve plate closes the first flow channel, and the second check valve plate closes the second flow channel.

[0018] When the two check valve plates synchronously open the corresponding first flow channel and second flow channel in the first state, the first check valve plate, the rectifier plate and the second check valve plate form a complete rectifier plate structure. The complete rectifier plate structure composed of the three has a longer extension length than the aforementioned single rectifier plate. In particular, after the second check valve plate is opened, the extension length of the rectifier plate is increased and can even extend beyond the air outlet, so that the airflow can still be guided by the second check valve when flowing out of the air outlet, thereby ensuring the guidance effect.

[0019] In order to ensure that the two check valve plates can effectively close the corresponding flow channels and avoid the problem of oil fume backflow, in the second state, the first check valve plate is inclined from the first side edge of the rectifier plate toward the side edge of the impeller adjacent to the air outlet, so that the first check valve plate is located as a whole in the first flow channel, and the second check valve plate covers the outlet of the second flow channel and is basically flush with the plane where the air outlet is located.

[0020] The above-mentioned first check valve plate is inclined when the first flow channel is closed. This arrangement can, on the one hand, ensure the sealing of the first flow channel cover and reduce the problem of oil fume backflow; on the other hand, it can prevent the oil fume carried by the low-energy fluid area above from condensing here and causing oil pollution to accumulate. It can also ensure that the oil pollution flows smoothly into the volute and is collected in the oil cup, avoiding the accumulation of oil pollution, breeding bacteria, and generating odor, which will cause trouble to users.

[0021] In order to realize the linkage cooperation between the two check valve plates and simplify the connection structure between the rectifier plate and the two check valve plates, a connecting rod mechanism connected between the first check valve plate and the second check valve plate is also included so that the two can be opened or closed synchronously. The connecting rod mechanism includes:

[0022] A first connecting rod is provided on the rectifying plate and has a first end located on the rectifying plate facing the impeller and a second end located on the rectifying plate facing away from the impeller, the first connecting rod being rotatably connected to the rectifying plate with a straight line parallel to the rotation center of the first check valve plate as a rotation axis;

[0023] a second connecting rod, a first end of which is rotatably connected to the first check valve plate, and a second end of which is rotatably connected to the first end of the first connecting rod;

[0024] A third connecting rod has a first end rotatably connected to the second check valve plate, and a second end rotatably connected to the second end of the first connecting rod.

[0025] In order to achieve adaptive diversion according to different air volumes, the rectifier plate and the first and second check valve plates arranged on the rectifier plate together constitute a check valve diversion assembly, and the check valve diversion assembly can also be driven by a driving mechanism to move closer to or away from the impeller to change the size of the first flow channel and the second flow channel.

[0026] Since the fan is in different air volume gears, the pressure gradient of the flow channel at the air outlet is also different. Therefore, the drive mechanism can be set to drive the check valve guide assembly to move forward and backward to match different pressure gradients.

[0027] In order to achieve stable sliding of the check valve guide assembly in the front-to-back direction, the air outlet of the volute has a slide groove arranged along the front-to-back direction in the area corresponding to the left and right sides of the rectifier plate, and the left and right sides of the rectifier plate are constrained in the corresponding slide grooves by means of pin shafts for forward and backward sliding. The driving mechanism includes a driving motor arranged on the rectifier plate, a gear is provided on the output shaft of the driving motor, and a rack is provided on the volute, the extension direction of which is consistent with the extension direction of the slide groove, and the gear is meshed with the rack.

[0028] The technical solution adopted by the present invention to solve the above-mentioned second technical problem is: a fan system, including two of the above-mentioned centrifugal fans, the two centrifugal fans are symmetrically arranged in the left and right directions, and the air outlets on the two centrifugal fan volutes are connected to form a complete air outlet.

[0029] For a fan system with two fans with check valves on the rectifier plate, when the impeller on one side is not running, the first check valve and the second check valve on the air outlet side can close the first flow channel and the second flow channel corresponding to the air outlet on that side to prevent backflow into the fan on the other side when the fan is started.

[0030] The technical solution adopted by the present invention to solve the above-mentioned third technical problem is: a range hood, including a casing and the above-mentioned fan system, the casing is flat as a whole, and the top of the casing has an opening that is opposite to the air outlet of the fan system and is used to connect to an external air outlet hood.

[0031] Compared with the prior art, the advantages of the present invention are as follows: the rectifier plate arranged at the air outlet with a turn of the volute can separate the flow channel at the air outlet into a first flow channel close to the impeller and a second flow channel away from the impeller, thereby not only reducing the low-energy fluid area and the reflow area at the air outlet, but also dispersing the high-pressure area at the outlet turn of the centrifugal fan, performing a passive "pressure relief" treatment on it, reducing the pressure gradient and velocity gradient at the turn, and preventing the high-pressure airflow from the outlet turn to the impeller area due to the increase of the flue resistance, causing the impeller to cut the high-pressure airflow and generate noise, thereby eliminating the "puff" return air abnormal sound under high resistance conditions. In the preferred embodiment, the rectifier plate is provided with a check valve sheet to form a check valve guide assembly, which can not only effectively dredge the flue airflow, prevent the backflow and accumulation of the airflow here, but also reduce the problem of oil fume backflow in the dual fan system in the single open state. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of smoke backflow of a dual-fan system in the prior art;

[0033] Figure 2 A schematic diagram of the three-dimensional structure of a fan system according to an embodiment of the present invention;

[0034] Figure 3 is a schematic diagram of the three-dimensional structure of the fan system according to an embodiment of the present invention from another angle;

[0035] Figure 4 for Figure 2 Schematic diagram of the three-dimensional structure after omitting the second cover plate on the top;

[0036] Figure 5 for Figure 2A schematic diagram of the three-dimensional structure after the check valve guide assembly at the air outlet of the volute of the right centrifugal fan is omitted;

[0037] Figure 6 is a schematic diagram of the three-dimensional structure of a range hood according to an embodiment of the present invention;

[0038] Figure 7 is a schematic diagram of the three-dimensional structure of the range hood according to the embodiment of the present invention from another angle;

[0039] Figure 8 It is a vertical cross-sectional view of a part of the range hood according to an embodiment of the present invention cut along the front-to-back direction (the check valve flow guide assembly is in a state of closing the corresponding first flow channel and the second flow channel);

[0040] Fig. 9 It is a vertical cross-sectional view of a part of the range hood according to an embodiment of the present invention cut along the front-to-back direction (the check valve flow guide assembly is in a state where the corresponding first flow channel and second flow channel are opened);

[0041] Fig.10 It is a schematic diagram of the three-dimensional structure of the flow guide assembly of the check valve according to the embodiment of the present invention in the second state;

[0042] Fig.11 It is a schematic diagram of the three-dimensional structure of the flow guide assembly of the check valve according to an embodiment of the present invention in a first state;

[0043] Fig.12 A vertical cross-sectional view of a portion of the range hood according to an embodiment of the present invention cut along the front-to-back direction;

[0044] Fig.13 A simulation speed cloud diagram comparing the range hood according to the embodiment of the present invention with a conventional range hood;

[0045] Fig.14 A simulated pressure cloud diagram comparing the range hood according to the embodiment of the present invention with a conventional range hood. DETAILED DESCRIPTION

[0046] The present invention is further described in detail below with reference to the accompanying drawings.

[0047] In the specification and claims of the present invention, terms indicating directions, such as "front", "rear", "up", "down", "left", "right", "side", "top", "bottom", etc., are used to describe various exemplary structural parts and elements of the present invention, but these terms are used here only for the purpose of convenience of description and are determined based on the exemplary orientations shown in the accompanying drawings. Since the embodiments disclosed in the present invention can be arranged in different directions, these terms indicating directions are only used as explanations and should not be regarded as limitations. For example, "up" and "down" are not necessarily limited to directions opposite to or consistent with the direction of gravity.

[0048] See also Figure 2-Figure 14 A fan system includes two centrifugal fans arranged symmetrically in the left-right direction, wherein each centrifugal fan includes a volute 10 and an impeller 20 disposed in the volute 10, and the impeller 20 is driven to rotate by a main motor 21 to provide negative pressure. The volute 10 includes a first cover plate 11 and a second cover plate 12 disposed opposite to each other and an annular wall 13 connected between the first cover plate 11 and the second cover plate 12.

[0049] The first cover plate 11 of the volute 10 is provided with an air inlet 110, which is directly opposite to the port of the impeller 20 and arranged downward. The second cover plate 12 of the volute 10 is provided with an air outlet 120, which is arranged upward, that is, parallel to the axial direction O of the impeller 20, see Figure 2 The air outlets 120 on the two centrifugal fan volutes 10 are connected to form a complete air outlet 120. The volutes 10 of the two centrifugal fans share the same annular wall 13 portion near the air outlet 120, that is, the volutes 10 of the two centrifugal fans share the same annular wall 13 portion to form a middle partition 132, which separates the flow channels at the air outlets 120 of the two centrifugal fans. The volute tongues 131 on the annular wall 13 of the two centrifugal fan volutes 10 are symmetrically arranged relative to the middle partition 132, see Figure 2 .

[0050] See also Figure 5 , shows a schematic diagram of the three-dimensional structure of the fan system after the check valve guide assembly 3 at the air outlet 120 of the right centrifugal fan volute 10 is omitted. It can be seen that in order to achieve the purpose of guiding the airflow inside the volute 10 to the air outlet 120 from the second cover plate 12, a guide plate 15 is also provided between the first cover plate 11 and the second cover plate 12 adjacent to the air outlet 120, which is inclined from the first cover plate 11 to the position of the air outlet 120 of the second cover plate 12 in the direction away from the impeller 20. The guide plate 15 is an arc-shaped plate, and the side wall surface of the guide plate 15 facing the impeller 20 is concave in the direction away from the impeller 20 to form a guide surface 150. Furthermore, an inclined guide vane 17 is also provided on the guide surface 150 of the guide plate 15, and the guide vane 17 extends from the above-mentioned guide surface to the direction away from the guide surface, which can improve the guide effect, suppress the airflow instability caused by uneven airflow caused by vortexes in the airflow near the guide surface, thereby reducing noise. For the structure and arrangement of the above-mentioned guide plate 17, please refer to the prior application of the applicant: application number 202011091494.0, entitled: "A guide device, a centrifugal fan and a range hood having the guide device", which will not be repeated here.

[0051] Each centrifugal fan of the fan system is provided with a check valve guide assembly 3 at the air outlet 120, wherein the check valve guide assembly 3 includes a rectifying plate 30, a first check valve plate 31 and a second check valve plate 32. Fig.10 and Fig.11 , two sets of symmetrical check valve guide assemblies 3 are shown. The two symmetrical check valve guide assemblies 3 can be installed at the air outlets 120 of two centrifugal fans of the fan system respectively.

[0052] See also Figure 4 The rectifying plate 30 is located on the side of the guide plate 15 facing the impeller 20 and is spaced apart from the guide plate 15. The left and right sides of the rectifying plate 30 are connected to the annular wall 13 of the volute 10. The upper side of the rectifying plate 30 is adjacent to the air outlet 120 and is substantially on the same horizontal plane as the air outlet 120. Specifically, the upper side of the rectifying plate 30 is recorded as the second side 302, and the lower side away from the air outlet 120 is recorded as the first side 301. Figure 8 It can be seen that the first side 301 of the rectifying plate 30 is spaced a certain distance from the first cover plate 11 of the volute 10, and is approximately located in the middle of the first cover plate 11 and the second cover plate 12. In order to ensure the smoothness of the airflow at the air outlet 120, the rectifying plate 30 is an arc-shaped plate substantially consistent with the inclination direction of the guide plate 15, thereby dividing the flow channel of the volute 10 at the air outlet 120 into a first flow channel 141 close to the impeller 20 and a second flow channel 142 away from the impeller 20.

[0053] The rectifier plate 30 arranged at the turned air outlet 120 of the volute 10 can separate the flow channel at the air outlet 120 into a first flow channel 141 close to the impeller 20 and a second flow channel 142 away from the impeller 20. Therefore, not only the low-energy fluid area and the recirculation area at the air outlet 120 are reduced, but also the high-pressure area at the turning point of the air outlet 120 of the centrifugal fan is dispersed, and a passive "pressure relief" treatment is performed on it, which reduces the pressure gradient and velocity gradient at the turning point, and prevents the high-pressure airflow from diffusing from the turning point of the air outlet 120 to the impeller 20 area due to the increase of flue resistance, causing the impeller 20 to cut the high-pressure airflow and generate noise, thereby eliminating the "puff" return air abnormal sound under high resistance conditions.

[0054] The first check valve plate 31 is rotatably connected to the first side 301 of the rectifying plate 30 via the first rotating shaft 331, and can open or close the first flow channel 141. The second check valve plate 32 is rotatably connected to the second side wall of the rectifying plate 30 via the second rotating shaft 332, and can open or close the second flow channel 142. Since the first check valve plate 31 and the second check valve plate 32 are respectively connected to two relatively far sides of the rectifying plate 30, the interference problem between the two check valve plates when they are opened is avoided, and there is no influence between the two, thereby ensuring the stability of the air outlet when the first flow channel 141 and the second flow channel 142 are opened.

[0055] The first check valve plate 31 and the second check valve plate 32 of this embodiment are connected by a connecting rod structure so as to be able to move synchronously. The connecting rod mechanism 40 includes a first connecting rod 41, a second connecting rod 42 and a third connecting rod 43 which are connected in sequence.

[0056] The rectifier plate 30 has a movable opening (not shown), and the first connecting rod 41 is inserted into the rectifier plate 30 through the movable opening. Specifically, the movable opening of the rectifier plate 30 has a third connecting seat 303 composed of a bent sheet, and the middle part of the first connecting rod 41 is rotatably connected to the third connecting seat 303 through a pin. The first connecting rod 41 has a first end located on the side of the rectifier plate 30 facing the impeller 20 and a second end located on the side of the rectifier plate 30 facing away from the impeller 20. The rotation axis of the first connecting rod 41 is parallel to the straight line of the rotation center of the first check valve plate 31 (or the straight line where the rotation center of the second check valve plate 32 is located).

[0057] The first end of the second connecting rod 42 is rotatably connected to the first connecting seat 310 on the first check valve plate 31, and the second end is rotatably connected to the first end of the first connecting rod 41. The first end of the third connecting rod 43 is rotatably connected to the second connecting seat 320 on the second check valve plate 32, and the second end is rotatably connected to the second end of the first connecting rod 41.

[0058] When the centrifugal fan is running, under the action of the air flow pressure, the two check valve plates of the check valve guide assembly 3 flip upward, thereby synchronously opening the corresponding first flow channel 141 and the second flow channel 142 in the first state, such as Figure 2 In the figure, the right fan of the fan system shows the first state in which the two check valves open the corresponding flow channels. In the first state, the first check valve 31 covers the wall surface of the rectifier plate 30 facing the impeller 20, and specifically can be attached to the wall surface of the rectifier plate 30. The second check valve 32 is connected to the area where the second side 302 of the rectifier plate 30 is located, and extends along the airflow direction of the second side 302 of the rectifier plate 30, so that the first check valve 31, the rectifier plate 30 and the second check valve 32 form a complete rectifier plate 30 structure, see Fig. 9 In the first state, the second check valve disc 32 tilts upward from front to back, so that when the centrifugal fan stops running, the second check valve disc 32 deflects downward under the action of gravity, and at the same time drives the first check valve disc 31 to deflect downward, thereby synchronously closing the corresponding first flow channel 141 and the second flow channel 142, so that the check valve guide assembly 3 remains in the second state.

[0059] In the first state where the two check valve plates synchronously open the corresponding first flow channel 141 and the second flow channel 142, the complete rectifier plate 30 structure formed by the first check valve plate 31, the rectifier plate 30 and the second check valve plate 32 has a longer extension length and can even extend beyond the air outlet 120, so that the airflow can still be guided by the second check valve when flowing out of the air outlet 120, thereby ensuring the guidance effect at the air outlet 120.

[0060] like Figure 2 As shown, the left fan of the fan system shows the second state in which the two check valves close the corresponding flow channels. In the second state, the first check valve 31 is inclined from the first side edge 301 of the rectifier plate 30 toward the side edge of the air outlet 120 adjacent to the impeller 20, so that the first check valve 31 is located in the first flow channel 141 as a whole. The second check valve 32 covers the outlet of the second flow channel 142 and is substantially flush with the plane where the air outlet 120 is located, see Figure 8 The first check valve plate 31 is arranged obliquely when the first flow channel 141 is closed. On the one hand, it can ensure the sealing of the first flow channel 141 and reduce the problem of oil fume backflow when the single-side fan is running; on the other hand, it can prevent the oil fume carried by the low-energy fluid area above from condensing here and causing oil pollution to accumulate, and can also ensure that the oil pollution flows smoothly into the volute 10 and is collected in the oil cup, avoiding the accumulation of oil pollution, breeding bacteria, and generating odor, which brings troubles to users.

[0061] Continue to see Figure 8 and Fig. 9 It can be seen that the first connecting rod 41 is a rod structure with a slight curvature, thereby ensuring that when the first check valve plate 31 is in the state of closing the first flow channel 141, the portion of the first connecting rod 41 located in the first flow channel 141 can basically fit with the guide surface of the rectifying plate 30, so that the first check valve plate 31 can also fit on the side wall of the rectifying plate 30 as much as possible, see Fig. 9 .

[0062] Since the fan is in different air volume gears, the pressure gradient of the flow channel at the air outlet 120 is also different. Therefore, in order to achieve adaptive diversion according to different air volumes, the check valve guide assembly 3 can also be driven by the driving mechanism to move closer to or farther away from the impeller 20, thereby changing the size of the first flow channel 141 and the second flow channel 142 (that is, the effective flow area) to match different pressure gradients. When the fan system switches to a high air volume gear, the second air channel away from the impeller 20 generates airflow accumulation, which increases the back pressure gradient. The check valve guide assembly 3 needs to move forward, that is, move in the direction close to the impeller 20, thereby increasing the effective flow area of ​​the second flow channel 142 and the effective flow area of ​​the first flow channel 141. Reduced, improve the airflow accumulation phenomenon. Conversely, when the fan system switches to a low air volume gear, the check valve guide assembly 3 moves backward, that is, moves in the direction away from the impeller 20, thereby increasing the effective flow area of ​​the first flow channel 141 and reducing the effective flow area of ​​the second flow channel 142. By adjusting the front and rear positions of the check valve guide assembly 3, the low-energy fluid area and the recirculation area at the top air outlet 120 can be improved in a targeted manner, and the airflow in the flow channel there is effectively unblocked to prevent the backflow and accumulation of the airflow here, thereby achieving the purpose of adaptive diversion, improving the overall performance of the range hood, and maximizing the air volume and reducing noise.

[0063] A driving motor 50 is also fixed on the rectifying plate 30, and a gear (not shown) is provided on the output shaft of the driving motor 50. A rack 52 extending forward and backward is provided on the middle partition 132 of the annular wall 13 of the volute 10, and the gear is meshed with the rack 52. When the driving motor 50 rotates forward and reversely, the rectifying plate 30 (and the two check valve plates provided on the rectifying plate 30) can be driven to move forward or backward through the gear rack transmission. In addition, in order to ensure that the rectifying plate 30 can slide stably in the front-to-back direction when driven by the driving motor 50, the rectifying plate 30 is also provided with a first limit stop shoulder 301 that can be placed on the top side edge of the middle partition 132 (extending horizontally in the front-to-back direction) adjacent to the top side edge of the middle partition 132, thereby ensuring that the rectifying plate 30 can slide smoothly in a straight line along the top side edge of the middle partition 132.

[0064] When the fan system is not running, the check valve guide assembly 3 is in the initial position as a whole. In this initial position, the two check valve plates on the rectifier plate 30 close the corresponding first flow channel 141 and the second flow channel 142 to prevent the backflow of oil smoke. When the fan system is running, the two check valve plates on the rectifier plate 30 are opened and in the diversion state. At this time, the position of the check valve guide assembly 3 can be adjusted according to the air volume of different gears (detected by the corresponding air volume or air pressure sensor) to match different pressure gradients and achieve the best diversion effect.

[0065] The present embodiment also relates to a range hood, comprising a housing 60 and the above-mentioned fan system. The housing 60 is flat as a whole, and the top of the housing 60 has an opening 61 directly opposite to the air outlet 120 of the fan system, which can be used to connect to an external air outlet hood (not shown). The bottom of the housing 60 has an air inlet 62, which is opposite to the air inlet 110 of the fan system. A butterfly plate 63 is also provided below the air inlet 62 of the housing 60, and a duct structure is formed between the butterfly plate 63 and the bottom wall of the housing 60 for external airflow to enter the air inlet 62.

[0066] See also Fig.13 and Fig.14 ,in, Fig.13 The simulation speed cloud diagram of the range hood of this embodiment compared with the conventional range hood is shown. Fig.13 The left part in the middle is a conventional range hood without the check valve guide assembly 3, and the right part is a range hood with the check valve guide assembly 3 of this embodiment. It can be seen that the airflow at the air outlet 120 of the conventional range hood without the check valve guide assembly 3 accumulates to the rear, and a large range of low-energy fluid area and recirculation area appear in the front. After adding the check valve guide assembly 3, the low-energy fluid area and the recirculation area are greatly reduced, which is conducive to the flow of air.

[0067] Fig.14 The simulated pressure cloud diagram comparing the range hood of this embodiment with the conventional range hood is shown. Fig.14 The left part in the middle is a conventional range hood without the check valve guide assembly 3, and the right part is a range hood in this embodiment with the check valve guide assembly 3. It can also be seen that the back pressure distribution at the air outlet 120 of the conventional range hood without the check valve guide assembly 3 is uneven, and the high-pressure area is obviously moved forward (towards the position of the impeller 20). After adding the check valve guide assembly 3, the back pressure distribution is improved, and the range of the high-pressure area is significantly reduced.

[0068] Through experimental tests, after adding the check valve guide component 3, while solving the above practical problems, the overall performance has also been improved (specifically, the air volume is increased and the noise is reduced), and the improvement effect is as follows:

[0069]

Claims

1. A centrifugal fan, comprising: A volute (10) and an impeller (20) disposed in the volute (10), wherein the volute (10) is provided with an air outlet (120), the air outlet direction of the air outlet (120) of the volute (10) is parallel to the axial direction (O) of the impeller (20), and the air outlet (120) of the volute (10) is provided with a guide surface (150) for guiding the airflow inside the volute (10) toward the air outlet (120); The invention is characterized in that it also includes: a rectifying plate (30) disposed in the volute (10), adjacent to the air outlet (120), and located on a side of the guide surface (150) facing the impeller (20), wherein the rectifying plate (30) separates a flow channel of the volute (10) at the air outlet (120) into a first flow channel (141) close to the impeller (20) and a second flow channel (142) away from the impeller (20); The volute (10) comprises a first cover plate (11), a second cover plate (12) and an annular wall (13) connected between the first cover plate (11) and the second cover plate (12); the first cover plate (11) is provided with an air inlet (110), the second cover plate (12) is provided with the air outlet (120); a guide plate (15) is provided between the first cover plate (11) and the second cover plate (12) adjacent to the air outlet (120), and is inclined from the first cover plate (11) to the position of the air outlet (120) of the second cover plate (12) in a direction away from the impeller (20); the side wall surface of the guide plate (15) facing the impeller (20) is the guide surface (150); and the rectifying plate (30) is an arc-shaped plate having a substantially consistent inclination direction with the guide plate (15); The rectifying plate (30) has a first side (301) away from the air outlet (120) and a second side (302) adjacent to the air outlet (120); the rectifying plate (30) is also provided with a first check valve plate (31) and a second check valve plate (32); the first check valve plate (31) is rotatably connected to the first side (301) of the rectifying plate (30) and can open or close the first flow channel (141); the second check valve plate (32) is rotatably connected to the second side wall of the rectifying plate (30) and can open or close the second flow channel (142); The first check valve plate (31) and the second check valve plate (32) are linked to each other, thereby having a first state of synchronously opening the corresponding first flow channel (141) and the second flow channel (142) and a second state of synchronously closing the corresponding first flow channel (141) and the second flow channel (142): In the first state, the first check valve plate (31) covers the wall surface of the rectifying plate (30) facing the impeller (20), and the second check valve plate (32) is connected to the area where the second side edge (302) of the rectifying plate (30) is located and extends along the flow direction of the airflow there, so that the first check valve plate (31), the rectifying plate (30) and the second check valve plate (32) form a complete rectifying plate (30) structure; In the second state, the first check valve plate (31) closes the first flow channel (141), and the second check valve plate (32) closes the second flow channel (142); It also includes a connecting rod mechanism (40) connected between the first check valve plate (31) and the second check valve plate (32) so that the two can be opened or closed synchronously, and the connecting rod mechanism (40) includes: A first connecting rod (41) is passed through the rectifying plate (30) and has a first end located on a side of the rectifying plate (30) facing the impeller (20) and a second end located on a side of the rectifying plate (30) facing away from the impeller (20). The first connecting rod (41) is rotatably connected to the rectifying plate (30) with a straight line parallel to the rotation center of the first check valve plate (31) as a rotation axis. a second connecting rod (42), a first end of which is rotatably connected to the first check valve plate (31), and a second end of which is rotatably connected to the first end of the first connecting rod (41); A third connecting rod (43) has a first end rotatably connected to the second check valve plate (32), and a second end rotatably connected to the second end of the first connecting rod (41).

2. The centrifugal fan according to claim 1, characterized in that: In the second state, the first check valve plate (31) is inclined from the first side edge (301) of the rectifying plate (30) toward the side edge of the air outlet (120) adjacent to the impeller (20), so that the first check valve plate (31) is entirely located in the first flow channel (141), and the second check valve plate (32) covers the outlet of the second flow channel (142) and is substantially flush with the plane where the air outlet (120) is located.

3. The centrifugal fan according to claim 1, characterized in that: The rectifying plate (30) and the first check valve plate (31) and the second check valve plate (32) arranged on the rectifying plate (30) together constitute a check valve guide assembly (3); the check valve guide assembly (3) can also be driven by a driving mechanism to move closer to or farther from the impeller (20) so as to change the size of the first flow channel (141) and the second flow channel (142).

4. The centrifugal fan according to claim 3, characterized in that: The air outlet (120) of the volute (10) is located in an area corresponding to the left and right sides of the rectifier plate (30) and has a slide groove arranged in the front-to-back direction. The left and right sides of the rectifier plate (30) are constrained in the corresponding slide grooves by means of a pin shaft to slide back and forth. The driving mechanism comprises a driving motor (50) arranged on the rectifier plate (30), a gear is arranged on the output shaft of the driving motor (50), and a rack (52) is arranged on the volute (10) with an extension direction consistent with the extension direction of the slide groove, and the gear is meshed with the rack (52).

5. A fan system, characterized in that: It comprises two centrifugal fans as claimed in any one of claims 1 to 4, the two centrifugal fans are symmetrically arranged in the left-right direction, and the air outlets (120) on the two centrifugal fan volutes (10) are connected to form a complete air outlet (120).

6. A range hood, characterized in that: It comprises a casing (60) and the fan system as claimed in claim 5, wherein the casing (60) is flat as a whole, and the top of the casing (60) has an opening (61) facing the air outlet (120) of the fan system and used to connect to an external air outlet cover.

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