A double-suction centrifugal fan having backward unequal-thickness curved blades

Abstract

This invention relates to the field of centrifugal fan technology, and particularly to a double-suction centrifugal fan with backward-curved blades of unequal thickness. The fan includes a volute, an impeller, and a collector. Both the impeller and the collector are housed within the volute, and the collector is fixedly connected to the volute. The impeller comprises a front plate and a rear plate, with multiple blades arranged in a circular array on the rear plate. An air intake is located in the center of the front plate. The impeller includes a first impeller and a second impeller with identical structures, symmetrically arranged on both sides of the rear plate. On the projection surface of the rear plate, the blades include straight sections away from the hub and curved sections near the hub. The curved sections include an outer arc and an inner arc. The minimum thickness of the curved sections is t1, and the maximum thickness is t2. The curved sections are configured with unequal thickness, where the thickness gradually increases from t1 to t2 and then gradually decreases back to t1. The thickness of the straight sections is t1, and t2 is 1.9-2.1 times that of t1. This invention, with its backward-curved blades, provides a double-suction centrifugal fan with higher pressure, higher efficiency, and lower noise.

Description

Technical Field

[0001] This invention relates to the field of centrifugal fan technology, and in particular to a double-suction centrifugal fan with backward-curved blades of unequal thickness. Background Technology

[0002] A double-suction centrifugal fan is a ventilation device that draws in gas symmetrically from both sides and relies on the centrifugal force generated by the rotation of the impeller to transport the medium. It can achieve an air volume of approximately twice that of a single-suction fan of the same specification without significantly increasing the radial dimension and inlet velocity of the machine, thus enabling large-volume air delivery. It is widely used in ventilation and air exchange in industrial fields such as factories, hotels, and shopping malls, as well as in civil fields.

[0003] Currently, dual-suction centrifugal fans generally suffer from problems such as insufficient pressure, low efficiency, and high noise, making it difficult to meet the needs of society and users.

[0004] Existing technology needs improvement. Summary of the Invention

[0005] The purpose of this invention is to provide a double-suction centrifugal fan with backward-curved blades of unequal thickness, which aims to solve the problems of insufficient pressure, low efficiency and high noise that are common in existing double-suction centrifugal fans.

[0006] To achieve the above objectives, a double-suction centrifugal fan with backward-curved blades of unequal thickness is provided, comprising a volute, an impeller, and a collector. Both the impeller and the collector are disposed within the volute, and the collector is fixedly connected to the volute. The impeller comprises a front plate and a rear plate, with multiple blades arranged in an array around the rear plate, and an air intake is provided in the center of the front plate.

[0007] The impeller includes a first impeller and a second impeller with identical structures and symmetrically arranged on both sides of the rear disc;

[0008] The blade includes a leading edge, a trailing edge, a first side connecting the first end of the leading edge and the trailing edge, and a second side connecting the second end of the leading edge and the trailing edge. The first side is the side closest to the air inlet, and the second side is the side furthest from the air inlet. The leading edge includes a leading edge arc segment connected to the first side and a leading edge straight segment connected to the second side. The leading edge straight segment is parallel to the trailing edge.

[0009] On the projection surface of the rear disc, the blade includes a straight section of the blade away from the hub and an arc section of the blade close to the hub. The arc section of the blade includes an outer arc and an inner arc. The minimum thickness of the arc section of the blade is t1 and the maximum thickness is t2. The arc section of the blade is set to a structure with unequal thickness, where the thickness gradually increases from t1 to t2 and then gradually decreases back to t1. The thickness of the straight section of the blade is t1, and t2 is 1.9-2.1 times that of t1.

[0010] The inlet angle ∠2 during blade installation is 151°-153°, and the outlet angle ∠3 during blade installation is 43.6°-44.4°.

[0011] There are 10 leaves.

[0012] Furthermore, the circumference diameter φ4 formed by the outermost ends of all the blades is 500mm, the circumference diameter φ5 formed by the innermost ends of all the blades is 310mm-312mm, and the diameter of the air inlet φ6 is 328.5mm-331.5mm.

[0013] On the projection surface of the rear disc, the length L2 of the straight section of the blade is 59.5mm-60.5mm, the radius R2 of the outer arc of the blade is 207mm-209mm and the arc length is 124mm-126mm, the radius R3 of the inner arc of the blade is 299mm-301mm and the arc length is 122mm-124mm, and t1 is 2.9mm-3.1mm.

[0014] Furthermore, the front disc is designed with a single-arc structure;

[0015] The impeller is sectioned by a plane passing through its central axis. On the cross-section:

[0016] The radius R5 of the front disc is 86mm-89mm and the arc length is 114mm-118mm. The radius R4 of the leading edge arc segment is 49mm-51mm and the arc length is 50mm-53mm. The length L4 of the leading edge straight segment is 156mm-158mm. The length L5 of the trailing edge is 158.5mm-161.5mm.

[0017] Furthermore, two conical guide plates are symmetrically arranged in the middle of the rear disc;

[0018] The height L3 of the air guide plate, from the air intake towards the rear plate, is 79.7mm-80.3mm;

[0019] The impeller is cut off by a plane passing through the central axis of the impeller. On the cross section, the radius R6 of the conical arc of the guide plate is 114mm-118mm and the arc length is 143mm-148mm.

[0020] Furthermore, the collector includes a connecting part and a guide section. The guide section includes a straight guide section connected to the connecting part and a curved guide section away from the connecting part. The collector is fixedly connected to the volute through the connecting part. The connecting part is annular and has an air inlet on its inner circumference. The outlet of the guide section is annular and has an air inlet on its inner circumference.

[0021] From the air inlet to the air outlet, the straight section of the air guide and a part of the curved section of the air guide form a tapering section, and another part of the curved section of the air guide forms a widening section. The air guide section is designed to be a guide structure that first tapes out from the tapering section to the widening section and then widens out.

[0022] The air guide arc section extends into the front disc of the impeller, and a radial clearance is provided between the collector and the impeller.

[0023] Furthermore, the diameter of the air inlet φ1 is 497mm-503mm, the diameter of the air guide φ3 is 323mm-327mm, and the diameter of the narrowest part of the air guide arc φ2 is 307.6mm-312.5mm;

[0024] The collector is cut off by a plane passing through the central axis of the collector. In the cross section: the radius R1 of the air guide arc is 49mm-51mm and the arc length is 81mm-83mm, the length L1 of the air guide straight section is 72mm-73mm, and the included angle ∠1 formed between the air guide straight section and the connecting part is 153°-157°.

[0025] The length L11 of the collector extending into the front disc of the impeller is 7.1mm-7.9mm, and the radial clearance length L12 between the collector and the impeller is 3.3mm-3.7mm.

[0026] Furthermore, the profile of the volute includes a first diffuser straight section, a volute tongue section, a first arc section, a second arc section, a third arc section, a fourth arc section, and a second diffuser straight section that are connected tangentially in sequence. The first diffuser straight section and the second diffuser straight section enclose and form an air outlet. The first arc section, the second arc section, the third arc section, and the fourth arc section are not concentric and their centers form an eccentric square.

[0027] A rectangular coordinate system is established with the impeller center O as the origin. When the first diffuser section is located in the second quadrant, the coordinates of the center O3 of the first arc segment are (-27.5, -7.5), the radius R8 is 289mm-290mm, and the arc length is 190mm-193mm. The coordinates of the center O4 of the second arc segment are (47.5, -7.5), the radius R9 is 365mm-366.5mm, and the arc length is 563mm-567mm. The coordinates of the third arc segment are... The center O1 of the circle has coordinates (47.5, 67.5), radius R10 has a length of 439.7mm-441.7mm and arc length of 689mm-695mm. The center O2 of the fourth arc segment has coordinates (-27.5, 67.5), radius R11 has a length of 514.5mm-517mm and arc length of 806mm-815mm. The first diffuser straight segment is set at an angle, and the included angle ∠5 formed by the first diffuser straight segment and the second diffuser straight segment is 59°-61°.

[0028] Furthermore, the height L9 of the air outlet is 595mm-605mm, and the width L10 of the air outlet is 642mm-653mm;

[0029] The radius R7 of the volute tongue segment is 16mm-17mm and the arc length is 62mm-64mm. The length L6 of the first diffuser straight segment is 220mm-224mm, and the length L8 of the second diffuser straight segment is 370mm-374mm. A tangent line is drawn to the volute tongue segment with the tangent point between the volute tongue segment and the first arc segment as the tangent point. The angle ∠4 between this tangent line and the first diffuser straight segment is 5.75°-6.44°.

[0030] Furthermore, the tongue of the volute is designed as a concave V-shaped structure, and the concave section of the concave V-shaped structure is designed as a rounded transition structure. The width L7 of the tongue gap is 82mm-84mm.

[0031] In the side view of the volute, the angle ∠6 between the concave section and the height direction of the air outlet is 68.8°-71.2°.

[0032] Furthermore, it also includes a motor, a drive shaft, a bearing bracket, a bearing, and a base. The motor is connected to the impeller via the drive shaft, and the drive shaft is mounted on the bearing bracket via the bearing. The volute, the motor, and the bearing bracket are all fixedly mounted on the base.

[0033] The distance between the bearing and the collector is L13, which is 0.35-0.45 times φ1.

[0034] The double-suction centrifugal fan with backward-curved blades of unequal thickness provided by the present invention has the following beneficial effects:

[0035] (1) The impeller adopts a double suction structure with symmetrical design on both sides of the rear plate. The blades adopt a biomimetic design with straight sections and curved arcs of unequal thickness. That is, the front section of the air inlet of the blade arc section adopts unequal thickness curvature and the rear section adopts a curved blade structure. The straight section of the blade adopts a straight design for air outlet. This combination allows the airflow to first climb and accelerate along the blade arc section and then smoothly transition along the blade straight section. Because the airflow can flow along the blade arc direction when it enters, the vortex area and impact area are reduced. The straight outlet is conducive to airflow stability, which improves the fan flow, pressure and efficiency and reduces the fan noise. The matching design of the number of blades, inlet angle and outlet angle, and the thickness of the blade arc section and the blade straight section further optimizes the gas flow path. The unequal thickness design can effectively reduce the maximum bending stress that the blades bear during operation, enhance the reliability of the blade structure, further improve the blockage at the impeller air inlet and suppress the internal separation of the impeller flow path, further improve the fan flow, pressure and efficiency and reduce the fan noise.

[0036] (2) The conical guide plates on both sides of the impeller rear plate are designed to match the movement trajectory of the airflow. The height and curvature of the guide plates are designed to guide the airflow, which effectively reduces the vortex generated by the direct impact of the airflow on the rear plate, thereby further improving the fan flow, pressure and efficiency, and further reducing the fan noise.

[0037] (3) The collector is designed by combining the air guide arc section and the air guide straight section. The air guide straight section and part of the air guide arc section form a tapering section, and the other part of the air guide arc section forms a widening section. The horn-shaped nozzle arc collector formed by stretching a certain arc and height is smoothly connected with the arc front plate to form a gap fit transition dock, which reduces the mutual impact loss of airflow, reduces the impact of airflow after entering the impeller to generate vortices, and accelerates the airflow. It effectively ensures that the airflow enters the impeller smoothly, increases the fan air volume and air pressure, and significantly improves the performance efficiency.

[0038] (4) An eccentric square logarithmic spiral volute profile structure is adopted, and the outward expansion design of the first diffuser straight section makes the airflow at the outlet form an angle, which can convert part of the kinetic energy of the airflow at the outlet into static pressure energy, ensuring smooth and efficient airflow in the volute, reducing the impact and energy loss of the airflow, and further improving the efficiency of the fan.

[0039] (5) The volute tongue adopts an inner groove, arc V-shaped deep tip design, and the outlet is a V-shaped opening with an arc transition at the V-shaped opening. The air outlet of the volute forms an accelerated pressure resistance section structure. By matching the design of the volute tongue section and the volute tongue gap, the curvature of the volute tongue section and the longitudinal offset of the volute tongue are changed, which reduces the airflow backflow area, reduces the air velocity at the outlet, reduces noise, and has higher static pressure efficiency.

[0040] (6) The fan structure adopts a two-bearing and volute separation design. The bearings at both ends are a certain distance away from the air inlet to avoid the bearings blocking the airflow into the collector, eliminating the impact of the airflow entering the impeller, and allowing the airflow to enter the impeller smoothly, which further improves the fan flow, pressure and efficiency, and reduces the fan noise. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the structure of a double-suction centrifugal fan with backward-curved blades of unequal thickness according to the present invention;

[0042] Figure 2 This is a schematic diagram of the profile of the volute.

[0043] Figure 3 This is a side view of the volute structure.

[0044] Figure 4 This is a schematic diagram of the three-dimensional structure of the cochlear tongue;

[0045] Figure 5 This is a schematic diagram of the impeller structure;

[0046] Figure 6 This is a side sectional view of the impeller.

[0047] Figure 7 This is a schematic diagram of the three-dimensional structure of the blade;

[0048] Figure 8 This is a side sectional view of the collector;

[0049] Figure 9 This is a performance curve diagram of the present invention;

[0050] Figure 10 This is a performance curve graph with a proportional ratio.

[0051] Explanation of reference numerals in the attached figures:

[0052] 1. Volute; 11. First diffuser straight section; 12. Volute tongue section; 13. First arc section; 14. Second arc section; 15. Third arc section; 16. Fourth arc section; 17. Second diffuser straight section; 18. Air outlet; 19. Volute tongue; 191. Concave section;

[0053] Impeller 2; First impeller 201; Second impeller 202; Blade 21; Straight section of blade 211; Arc section of blade 212; Outer arc of blade 213; Inner arc of blade 214; Leading edge arc section 215; Straight section of leading edge 216; Trailing edge 217; Front plate 22; Rear plate 23; Guide plate 231; Air inlet 24;

[0054] Collector 3; Connector 31; Air guide section 32; Straight air guide section 321; Arc air guide section 322; Air inlet 33; Air outlet 34;

[0055] 4. Drive shaft; 5. Bearing bracket; 6. Base. Detailed Implementation

[0056] The present invention will be described in detail below with reference to specific embodiments.

[0057] In this invention, unless otherwise explicitly specified and limited, terms such as "set in," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or a connection through one or more intermediate media. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. The directional terms appearing in this invention are for the purpose of better describing the characteristics of the features and the relationships between them. It should be understood that when the orientation of this invention changes, the orientation of the characteristics of the features and the relationships between them also changes accordingly. Therefore, directional terms do not constitute an absolute spatial limitation on the characteristics of the features and the relationships between them, but only a relative limitation.

[0058] The structural parameters used in this invention are only for illustrating the technical solution of this invention. That is, based on the basic structural parameters of this invention, reasonable proportional scaling can be performed in actual production (for example, when the diameter of the outer circumference circle formed by the outer ends of all the blades of the impeller is 500mm, it can be scaled by 0.1-30 times, etc.). Such reasonable proportional scaling also falls within the protection scope of this invention.

[0059] Please see Figure 1-10 A double-suction centrifugal fan with backward-curved blades of unequal thickness includes a volute 1, an impeller 2, and a collector 3. The impeller 2 and the collector 3 are both disposed inside the volute 1, and the collector 3 is fixedly connected to the volute 1. The impeller 2 includes a front plate 22 and a rear plate 23. Multiple blades 21 are arranged in a ring on the rear plate 23, and an air inlet 24 is provided in the middle of the front plate 22.

[0060] Impeller 2 includes a first impeller 201 and a second impeller 202 with the same structure and symmetrically arranged on both sides of the rear disc 23;

[0061] The blade 21 includes a leading edge, a trailing edge 217, a first side connecting the first end of the leading edge and the trailing edge 217, and a second side connecting the second end of the leading edge and the trailing edge 217. The first side is the side closest to the air inlet 24, and the second side is the side furthest from the air inlet 24. The leading edge includes a leading edge arc segment 215 connected to the first side and a leading edge straight segment 216 connected to the second side. The leading edge straight segment 216 is parallel to the trailing edge 217.

[0062] On the projection surface of the rear disc 23, the blade 21 includes a straight blade section 211 away from the hub and an arc blade section 212 close to the hub. The arc blade section 212 includes an outer arc 213 and an inner arc 214. The minimum thickness of the arc blade section 212 is t1 and the maximum thickness is t2. The arc blade section 212 is set to a structure with an unequal thickness where the thickness gradually increases from t1 to t2 and then gradually decreases back to t1. The thickness of the straight blade section 211 is t1, and t2 is 1.9-2.1 times that of t1.

[0063] The inlet angle ∠2 of blade 21 during installation is 151°-153°, and the outlet angle ∠3 of blade 21 during installation is 43.6°-44.4°; preferably, ∠2 is 152° and ∠3 is 44°.

[0064] There are 10 leaves.

[0065] Through the above technical solution, compared with conventional single-plate curved and airfoil-shaped impellers 2, the impeller 2 of this application adopts a double-suction structure symmetrically designed on both sides of the rear plate 23. The blades 21 adopt a biomimetic design of straight sections and arc-shaped unequal thickness bends. That is, the front section of the air inlet end of the blade arc section 212 adopts an unequal thickness bend and the rear section adopts a curved blade structure, and the straight section of the blade 211 adopts a straight design for air outlet. This combination allows the airflow to first climb and accelerate along the blade arc section 212 and then smoothly transition along the blade straight section 211. Because the airflow can flow along the blade arc direction when it enters, the vortex region and the impact are reduced. The straight outlet of the blower is conducive to airflow stability, which improves the fan flow rate, pressure and efficiency, and reduces fan noise. The matching design of the number of blades 21, the inlet and outlet angles, and the thickness of the blade arc section 212 and the blade straight section 211 further optimizes the gas flow path. The unequal thickness design can effectively reduce the maximum bending stress on the blades during operation, enhance the reliability of the blade 21 structure, further improve the blockage at the impeller 2 air inlet 24 and suppress the internal separation of the impeller flow channel, further improve the fan flow rate, pressure and efficiency and reduce fan noise.

[0066] In this embodiment, the circumferential diameter φ4 formed by the outermost ends of all blades 21 is 500mm, the circumferential diameter φ5 formed by the innermost ends of all blades 21 is 310mm-312mm, and the diameter φ6 of the air intake 24 is 328.5mm-331.5mm; preferably, φ5 is 311mm and φ6 is 330mm.

[0067] On the projection plane of the rear disc 23, the length L2 of the straight section 211 of the blade is 59.5mm-60.5mm, the radius R2 of the outer arc 213 of the blade is 207mm-209mm and the arc length is 124mm-126mm, the radius R3 of the inner arc 214 of the blade is 299mm-301mm and the arc length is 122mm-124mm, and t1 is 2.9mm-3.1mm. Preferably, L2 is 60mm, R2 is 208.2mm and the arc length is 125.2mm, and R3 is 300mm and the arc length is 122.9mm.

[0068] Through the above technical solution, the parameters such as impeller diameter, blade curvature, and blade length were optimized. The combination of unequal thickness bending at the front end of the blade arc section 212 and curved blade structure at the rear end, and straight design of the blade straight section 211 for air outlet, allows the airflow to first climb and accelerate along the blade arc section 212 and then smoothly transition along the blade straight section 211. Because the airflow can flow along the blade arc direction when it enters, the vortex zone and impact zone are reduced. The straight outlet is conducive to airflow stability, improves the fan flow, pressure and efficiency, and reduces fan noise.

[0069] In this embodiment, the front disc 22 is configured as a single arc-shaped structure;

[0070] Take a section of impeller 2 with a plane passing through the central axis of impeller 2. On the cross-section:

[0071] The radius R5 of the front disc 22 is 86mm-89mm and the arc length is 114mm-118mm; the radius R4 of the leading edge arc segment 215 is 49mm-51mm and the arc length is 50mm-53mm; the length L4 of the leading edge straight segment 216 is 156mm-158mm; and the length L5 of the trailing edge 217 is 158.5mm-161.5mm. Preferably, R5 is 87.5mm and the arc length is 116.2mm, R4 is 50mm and the arc length is 51.5mm, and L5 is 160mm.

[0072] Through the above technical solutions, the arc-shaped front plate 22 and the arc-segment plus straight-segment leading edge design further optimize the path of airflow into impeller 2, guide the airflow into the flow channel of impeller 2 more efficiently, improve the fan flow and efficiency, and reduce fan noise.

[0073] In this embodiment, two conical guide plates 231 are symmetrically arranged in the middle of the rear plate 23;

[0074] From the air intake 24 toward the rear plate 23, the height L3 of the guide plate 231 is 79.7mm-80.3mm; preferably, L3 is 80mm.

[0075] The impeller 2 is cut along a plane passing through its central axis. In the cross-section, the radius R6 of the conical arc of the guide plate 231 is 114mm-118mm and the arc length is 143mm-148mm. Preferably, R6 is 116mm and the arc length is 145.6mm.

[0076] Through the above technical solution, the conical guide disks 231 with symmetrical design on both sides of the rear disc 23 of the impeller 2 are designed with the height and curvature of the guide disks 231 to match the movement trajectory of the airflow, which effectively reduces the vortex generated by the direct impact of the airflow on the rear disc 23, thereby further improving the fan flow, pressure and efficiency, and further reducing the fan noise.

[0077] In this embodiment, the collector 3 includes a connecting part 31 and an air guide section 32. The air guide section 32 includes a straight air guide section 321 connected to the connecting part 31 and an arc-shaped air guide section 322 away from the connecting part 31. The collector 3 is fixedly connected to the volute 1 through the connecting part 31. The connecting part 31 is annular and has an air inlet 33 formed on its inner circumference. The outlet of the air guide section 32 is annular and has an air guide outlet 34 formed on its inner circumference.

[0078] From the air inlet 33 to the air guide 34, the straight section 321 and part of the curved section 322 form a tapering section, and another part of the curved section 322 forms a widening section. The air guide section 32 is configured as an air guide structure that first tapes out from the tapering section to the widening section and then widens.

[0079] The air guide arc section 322 extends into the front disc 22 of the impeller 2, and a radial gap is provided between the collector 3 and the impeller 2.

[0080] Through the above technical solution, the collector 3, through the combined design of the air guide arc section 322 and the air guide straight section 321 of the air guide section 32, forms a tapering section with the air guide straight section 321 and part of the air guide arc section 322, and another part of the air guide arc section 322 forms a widening section. The funnel-shaped collector 3, which is stretched to a certain arc and height, forms a smooth transition with the arc-shaped front plate 22 to form a gap fit, which reduces the mutual impact loss of airflow, reduces the impact of airflow entering the impeller 2 to generate vortices, and accelerates the airflow. This effectively ensures that the airflow enters the impeller 2 smoothly, increases the fan's air volume and air pressure, and significantly improves its performance and efficiency.

[0081] In this embodiment, the diameter φ1 of the air inlet 33 is 497mm-503mm, the diameter φ3 of the air guide 34 is 323mm-327mm, and the diameter φ2 at the narrowest point of the air guide arc 322 is 307.6mm-312.5mm; preferably, φ1 is 500mm, φ3 is 325mm, and φ2 is 310mm.

[0082] The collector 3 is cut along a plane passing through its central axis. In the cross-section: the radius R1 of the air guide arc 322 is 49mm-51mm and the arc length is 81mm-83mm; the length L1 of the air guide straight section 321 is 72mm-73mm; and the included angle ∠1 formed between the air guide straight section 321 and the connecting part 31 is 153°-157°. Preferably, R1 is 50mm and the arc length is 81.6mm, L1 is 72.5mm, and ∠1 is 155°.

[0083] The collector 3 extends into the front disc 22 of the impeller 2 by a length L11 of 7.1mm-7.9mm, and the radial clearance length L12 between the collector 3 and the impeller 2 is 3.3mm-3.7mm. Preferably, L11 is 7.5mm and L12 is 3.5mm.

[0084] In this embodiment, the profile of the volute 1 includes a first diffuser straight section 11, a volute tongue section 12, a first arc section 13, a second arc section 14, a third arc section 15, a fourth arc section 16, and a second diffuser straight section 17 connected tangentially in sequence. The first diffuser straight section 11 and the second diffuser straight section 17 enclose and form an air outlet 18. The first arc section 13, the second arc section 14, the third arc section 15, and the fourth arc section 16 are not concentric and their centers form an eccentric square.

[0085] A rectangular coordinate system is established with the center O of impeller 2 as the origin. When the first diffuser section 11 is located in the second quadrant, the coordinates of the center O3 of the first arc section 13 are (-27.5, -7.5), the radius R8 is 289mm-290mm, and the arc length is 190mm-193mm. The coordinates of the center O4 of the second arc section 14 are (47.5, -7.5), the radius R9 is 365mm-366.5mm, and the arc length is 563mm-567mm. The coordinates of the third arc section 15 are... The center O1 of the circle has coordinates (47.5, 67.5), radius R10 has a length of 439.7mm-441.7mm and arc length of 689mm-695mm. The center O2 of the fourth arc segment 16 has coordinates (-27.5, 67.5), radius R11 has a length of 514.5mm-517mm and arc length of 806mm-815mm. The first expanding straight segment 11 is inclined, and the included angle ∠5 formed by the first expanding straight segment 11 and the second expanding straight segment 17 is 59°-61°. Preferably, R8 is 289.5mm and arc length is 191.5mm, R9 is 365.7mm and arc length is 565.1mm, R10 is 440.7mm and arc length is 692.2mm, R11 is 515.7mm and arc length is 810.1mm, and ∠5 is 60°.

[0086] Through the above technical solution, the structure of the impeller 2 and the collector 3 is matched, and an eccentric square logarithmic spiral volute profile structure is adopted. The outward expansion design of the first diffuser straight section 11 makes the airflow at the outlet 18 form an angle, which enables part of the kinetic energy of the airflow at the outlet 18 to be converted into static pressure energy, ensuring smooth and efficient airflow in the volute 1, reducing the impact and energy loss of the airflow, and further improving the efficiency of the fan.

[0087] In this embodiment, the height L9 of the air outlet 18 is 595mm-605mm, and the width L10 of the air outlet 18 is 642mm-653mm; preferably, L9 is 600mm and L10 is 647.6mm.

[0088] The radius R7 of the volute tongue segment 12 is 16mm-17mm and the arc length is 62mm-64mm. The length L6 of the first diffuser straight segment 11 is 220mm-224mm, and the length L8 of the second diffuser straight segment 17 is 370mm-374mm. A tangent line is drawn to the volute tongue segment 12 with the tangent point between it and the first diffuser straight segment 13. The angle ∠4 between this tangent line and the first diffuser straight segment 11 is 5.75°-6.44°. Preferably, R7 is 16.5mm and the arc length is 62.7mm, L6 is 222mm, L8 is 372.5mm, and ∠4 is 6.1°.

[0089] Through the above technical solution, the air outlet 18 is designed with a certain width and height to match the impeller 2. The inclined air outlet 18 pressure-resistant section design ensures smooth and efficient airflow within the volute 1, reduces airflow impact and energy loss, and improves fan efficiency.

[0090] In this embodiment, the volute tongue 19 of the volute 1 is configured as a concave V-shaped structure, and the concave section 191 of the concave V-shaped structure is configured as a rounded transition structure. The width L7 of the volute tongue gap is 82mm-84mm; preferably, L7 is 83mm.

[0091] In the side view of the volute 1, the angle ∠6 between the concave section 191 and the air outlet 18 in the height direction is 68.8°-71.2°. Preferably, ∠6 is 70°.

[0092] Through the above technical solution, the volute tongue 19 adopts an inner groove arc V-shaped deep tip design, and the outlet has a V-shaped opening with an arc transition at the V-shaped opening. The air outlet 18 of the volute 1 forms an accelerated pressure resistance section structure. By matching the design of the volute tongue section 12 and the volute tongue gap to change the curvature of the volute tongue section 12 and the longitudinal offset of the volute tongue 19, the airflow backflow area is reduced, the air velocity of the air outlet 18 is reduced, the noise is reduced, and the static pressure efficiency is higher.

[0093] In this embodiment, it also includes a motor, a drive shaft 4, a bearing bracket 5, a bearing, and a base 6. The motor is connected to the impeller 2 via the drive shaft 4. The drive shaft 4 is mounted on the bearing bracket 5 via the bearing. The volute 1, the motor, and the bearing bracket 5 are all fixedly mounted on the base 6.

[0094] The distance between the bearing and the collector 3 is L13, where L13 is 0.35-0.45 times φ1. Preferably, L13 is 0.4 times φ1.

[0095] Through the above technical solution, the fan structure adopts a design with two bearings and the volute 1 separated. The bearings at both ends are a certain distance away from the air inlet 33 to avoid the bearings blocking the airflow into the collector 3, eliminate the impact of the airflow entering the impeller 2, and allow the airflow to enter the impeller 2 smoothly, which further improves the fan flow, pressure and efficiency, and reduces the fan noise.

[0096] It should be noted that the essential components involved in this invention, such as the motor, transmission shaft 4, bearing bracket 5, and base 6, are not improvements of this invention, and those skilled in the art are familiar with the structure and working principle of the basic components, so they will not be described in detail here.

[0097] To verify this embodiment, based on the preferred structural parameters provided in this embodiment, a double-suction centrifugal fan with backward-curved blades of unequal thickness was tested using an impeller 2 with a diameter of 600 mm (i.e., the diameter of the outer circumference formed by the outer ends of all blades 21 of the impeller 2). Simultaneously, a conventional double-suction centrifugal fan with an impeller 2 having a diameter of 600 mm and conventional blades 21 was tested as a comparative example. The test results were converted to atmospheric pressure of 101325 Pa, atmospheric temperature of 20 ℃, fan speed of 2450 r / min, and medium density of 1.2 kg / m³. 3 Test data under test conditions, and test examples yielded the test data shown in Table 1. Figure 9 The performance curves shown are used to derive test data as shown in Table 2. Figure 10 The performance curves shown represent the volumetric flow rate (qvsglGu), A-weighted sound level (LAGu), fan efficiency (ηr), impeller power (PrGu), total pressure (pFGu), and static pressure (psFGu).

[0098] Table 1

[0099]

[0100] Table 2

[0101]

[0102] The test data and performance curves show that, compared to the comparative example and the test case, under the same or similar impeller power settings, the embodiment outperforms the comparative example in terms of fan efficiency, total pressure, and A-weighted sound level. Specifically, the test case achieved an optimal fan efficiency of 80.602% at its second operating point, with a total pressure of 2773.5 Pa and an A-weighted sound level of 92.353 dB; while the comparative example achieved an optimal fan efficiency of 70.272% at its second operating point, with a total pressure of 2417.5 Pa and an A-weighted sound level of 94.753 dB. The test case generally exhibits higher total pressure and efficiency, and lower fan noise than the comparative example.

[0103] Meanwhile, with the same or similar impeller power, in the test example, during the stable operation of the fan at operating points 2-5, the fan efficiency ranged from 74.738% to 80.602%, the total pressure ranged from 1866.7 Pa to 2773.5 Pa, and the A-weighted sound level ranged from 91.026 dB to 92.353 dB. In the comparative example, during the stable operation of the fan at operating points 2-5, the fan efficiency ranged from 66.968% to 70.272%, the total pressure ranged from 1663.9 Pa to 2417.5 Pa, and the A-weighted sound level ranged from 93.226 dB to 94.753 dB.

[0104] The results above show that the double-suction centrifugal fan with backward-curved blades of unequal thickness of the present invention has higher pressure, higher efficiency and lower noise.

[0105] Where there is no conflict, the above embodiments and features can be combined with each other.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A double-suction centrifugal fan with backward-curved blades of unequal thickness, comprising a volute, an impeller, and a collector, wherein the impeller and the collector are both disposed within the volute, and the collector is fixedly connected to the volute; the impeller comprises a front plate and a rear plate, wherein multiple blades are arranged in a circumferential array on the rear plate, and an air intake is disposed in the center of the front plate, characterized in that: The impeller includes a first impeller and a second impeller with identical structures and symmetrically arranged on both sides of the rear disc; The blade includes a leading edge, a trailing edge, a first side connecting the first end of the leading edge and the trailing edge, and a second side connecting the second end of the leading edge and the trailing edge. The first side is the side closest to the air inlet, and the second side is the side furthest from the air inlet. The leading edge includes a leading edge arc segment connected to the first side and a leading edge straight segment connected to the second side. The leading edge straight segment is parallel to the trailing edge. On the projection surface of the rear disc, the blade includes a straight section of the blade away from the hub and an arc section of the blade close to the hub. The arc section of the blade includes an outer arc and an inner arc. The minimum thickness of the arc section of the blade is t1 and the maximum thickness is t2. The arc section of the blade is set to a structure with unequal thickness, where the thickness gradually increases from t1 to t2 and then gradually decreases back to t1. The thickness of the straight section of the blade is t1, and t2 is 1.9-2.1 times that of t1. The inlet angle ∠2 during blade installation is 151°-153°, and the outlet angle ∠3 during blade installation is 43.6°-44.4°. The number of leaves is 10; The diameter of the circle formed by the outermost ends of all the blades, φ4, is 500mm; the diameter of the circle formed by the innermost ends of all the blades, φ5, is 310mm-312mm; and the diameter of the air inlet, φ6, is 328.5mm-331.5mm. On the projection surface of the rear disc, the length L2 of the straight section of the blade is 59.5mm-60.5mm, the radius R2 of the outer arc of the blade is 207mm-209mm and the arc length is 124mm-126mm, the radius R3 of the inner arc of the blade is 299mm-301mm and the arc length is 122mm-124mm, and t1 is 2.9mm-3.1mm. The front disc is designed with a single-arc structure; The impeller is sectioned by a plane passing through its central axis. On the cross-section: The radius R5 of the front disc is 86mm-89mm and the arc length is 114mm-118mm; the radius R4 of the leading edge arc segment is 49mm-51mm and the arc length is 50mm-53mm; the length L4 of the leading edge straight segment is 156mm-158mm; and the length L5 of the trailing edge is 158.5mm-161.5mm. Two conical guide plates are symmetrically arranged in the middle of the rear disc; The height L3 of the air guide plate, from the air intake towards the rear plate, is 79.7mm-80.3mm; The impeller is cut off by a plane passing through the central axis of the impeller. On the cross section, the radius R6 of the conical arc of the guide plate is 114mm-118mm and the arc length is 143mm-148mm. The collector includes a connecting part and a guide section. The guide section includes a straight guide section connected to the connecting part and an arc guide section away from the connecting part. The collector is fixedly connected to the volute through the connecting part. The connecting part is annular and has an air inlet on its inner circumference. The outlet of the guide section is annular and has an air inlet on its inner circumference. From the air inlet to the air outlet, the straight section of the air guide and a part of the curved section of the air guide form a tapering section, and another part of the curved section of the air guide forms a widening section. The air guide section is designed to be a guide structure that first tapes out from the tapering section to the widening section and then widens out. The air guide arc section extends into the front disc of the impeller, and a radial clearance is provided between the collector and the impeller.

2. A double-suction centrifugal fan with backward-curved blades of unequal thickness according to claim 1, characterized in that: The diameter of the air inlet φ1 is 497mm-503mm, the diameter of the air guide φ3 is 323mm-327mm, and the diameter of the narrowest part of the air guide arc φ2 is 307.6mm-312.5mm. The collector is cut off by a plane passing through the central axis of the collector. In the cross section: the radius R1 of the air guide arc is 49mm-51mm and the arc length is 81mm-83mm, the length L1 of the air guide straight section is 72mm-73mm, and the included angle ∠1 formed between the air guide straight section and the connecting part is 153°-157°. The length L11 of the collector extending into the front disc of the impeller is 7.1mm-7.9mm, and the radial clearance length L12 between the collector and the impeller is 3.3mm-3.7mm.

3. A double-suction centrifugal fan with backward-curved blades of unequal thickness according to claim 2, characterized in that: The profile of the volute includes a first diffuser straight section, a volute tongue section, a first arc section, a second arc section, a third arc section, a fourth arc section, and a second diffuser straight section that are connected tangentially in sequence. The first diffuser straight section and the second diffuser straight section enclose and form an air outlet. The first arc section, the second arc section, the third arc section, and the fourth arc section are not concentric and their centers form an eccentric square. A rectangular coordinate system is established with the impeller center O as the origin. When the first diffuser section is located in the second quadrant, the coordinates of the center O3 of the first arc segment are (-27.5, -7.5), the radius R8 is 289mm-290mm, and the arc length is 190mm-193mm. The coordinates of the center O4 of the second arc segment are (47.5, -7.5), the radius R9 is 365mm-366.5mm, and the arc length is 563mm-567mm. The coordinates of the third arc segment are... The center O1 of the circle has coordinates (47.5, 67.5), radius R10 has a length of 439.7mm-441.7mm and arc length of 689mm-695mm. The center O2 of the fourth arc segment has coordinates (-27.5, 67.5), radius R11 has a length of 514.5mm-517mm and arc length of 806mm-815mm. The first diffuser straight segment is set at an angle, and the included angle ∠5 formed by the first diffuser straight segment and the second diffuser straight segment is 59°-61°.

4. A double-suction centrifugal fan with backward-curved blades of unequal thickness according to claim 3, characterized in that: The height of the air outlet L9 is 595mm-605mm, and the width of the air outlet L10 is 642mm-653mm; The radius R7 of the volute tongue segment is 16mm-17mm and the arc length is 62mm-64mm. The length L6 of the first diffuser straight segment is 220mm-224mm, and the length L8 of the second diffuser straight segment is 370mm-374mm. A tangent line is drawn to the volute tongue segment with the tangent point between the volute tongue segment and the first arc segment as the tangent point. The angle ∠4 between this tangent line and the first diffuser straight segment is 5.75°-6.44°.

5. A double-suction centrifugal fan with backward-curved blades of unequal thickness according to claim 4, characterized in that: The volute tongue is designed with a concave V-shaped structure, and the concave section of the concave V-shaped structure is designed with a rounded transition structure. The width L7 of the volute tongue gap is 82mm-84mm. In the side view of the volute, the angle ∠6 between the concave section and the height direction of the air outlet is 68.8°-71.2°.

6. A double-suction centrifugal fan with backward-curved blades of unequal thickness according to claim 5, characterized in that: It also includes a motor, a drive shaft, a bearing bracket, a bearing, and a base. The motor is connected to the impeller via the drive shaft, and the drive shaft is mounted on the bearing bracket via the bearing. The volute, the motor, and the bearing bracket are all fixedly mounted on the base. The distance between the bearing and the collector is L13, which is 0.35-0.45 times φ1.

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