A centrifugal ventilator for agricultural seeding machinery

Abstract

The present invention relates to the field of centrifugal fan industry, and particularly relates to a centrifugal ventilator for agricultural seeding machinery, which comprises a volute, an impeller and a collector. The volute and the collector are fixedly connected, and the impeller is arranged inside the volute. The impeller includes a front disc and a rear disc. An air suction port is arranged in the middle of the front disc. A plurality of blades are arranged in a circumferential array on the rear disc. The outlet angle ∠2 of the large blade during installation is 166°-170°. On the projection plane of the rear disc, the length L5 of the straight blade part is 112-115, the radius R5 of the curved blade part and the small blade is 28.8-30.3, and the arc length is 48.7-51.3. A radial clearance L12 is arranged between the collector and the impeller, and L12 is 4.5-5.5. The centrifugal ventilator for agricultural seeding machinery of the present invention has an increased total pressure of the fan, a larger volume flow rate, a higher fan efficiency, and a lower fan noise, achieving the effects of improving the fan efficiency, increasing the fan flow rate range and reducing the noise, and can effectively control the seeding speed and distance, and improve the seeding environment.

Description

Technical Field

[0001] The present invention relates to the field of centrifugal fans, and particularly to a centrifugal ventilator for agricultural seeding machinery. Background Art

[0002] In modern agricultural production, the popularization rate of agricultural mechanization is getting higher and higher. As a key pneumatic conveying device in agricultural machinery, the performance of the centrifugal ventilator directly affects the efficiency and energy efficiency of agricultural seeding machinery. In recent years, with the continuous improvement of the global requirements for energy conservation and environmental protection, although the performance indicators of centrifugal ventilators have been increasingly improved, the centrifugal ventilators currently used in agricultural seeding machinery still generally have problems such as low flow rate, insufficient pressure, low efficiency, and excessive noise, making it difficult to meet the requirements of society and users.

[0003] Therefore, the performance of the centrifugal ventilators currently used in agricultural seeding machinery needs to be further optimized. Summary of the Invention

[0004] The purpose of the present invention is to provide a centrifugal ventilator for agricultural seeding machinery, aiming to solve the problems of low flow rate, insufficient pressure, low efficiency, and high noise of centrifugal fans in the prior art.

[0005] To achieve the above purpose, the present invention provides a centrifugal ventilator for agricultural seeding machinery, including a volute, an impeller, and a collector. The volute and the collector are fixedly connected, and the impeller is arranged inside the volute; the impeller includes a front disc and a rear disc. An air suction port is arranged in the middle of the front disc, and a plurality of blades are arranged in a circumferential array on the rear disc;

[0006] The blades are of sheet metal structure, including large blades and small blades. Two small blades are arranged between two adjacent large blades, and the quantity ratio of large blades to small blades is 1:2;

[0007] The large blade includes a straight blade part, a curved blade part, a circular arc-shaped leading edge arranged at the front end of the straight blade part, a trailing edge arranged at the end of the curved blade part, a first side edge connecting between the first ends of the leading edge and the trailing edge, and a second side edge connecting between the second ends of the leading edge and the trailing edge. The first side edge is the side close to the air suction port, and the second side edge is the side far from the air suction port. The leading edge includes a first straight line segment, an arc segment, and a second straight line segment connected in sequence. The first straight line segment is connected to the first side edge, and the second straight line segment is connected to the second side edge. The leading edge inclines from the first straight line segment to the second straight line segment in the direction of the wheel shaft of the impeller;

[0008] In dimensionless terms, the outlet angle ∠2 of the large blade during installation is 166° - 170°. On the projection plane of the rear disc, the length L5 of the straight blade part is 112 - 115, the radius R5 of the curved blade part and the small blade is 28.8 - 30.3, and the arc length is 48.7 - 51.3;

[0009] The diameter φ1 of the outer peripheral circle formed by the outer ends of all the blades of the impeller is 495 - 505, the diameter φ2 of the inner peripheral circle formed by the inner ends of all the small blades is 428 - 434, the diameter φ3 of the inner peripheral circle formed by the inner ends of all the large blades is 199 - 201, and the width L8 of the trailing edge is 104.5 - 107.5;

[0010] A radial gap L12 is provided between the collector and the impeller, and L12 is 4.5 - 5.5.

[0011] Further, ∠2 is 168°, L5 is 113.6, R5 is 29.5 and the arc length is 50, φ1 is 500, φ2 is 430.9, φ3 is 200, L8 is 106, and L12 is 5;

[0012] The number of large blades is 16, and the number of small blades is 32.

[0013] Further, the impeller is intercepted by a plane passing through the central axis of the impeller. On the cross-section, the diameter φ4 of the air suction port is 422 - 428, the length L6 of the first straight line segment is 5.5 - 6.5, the radius R6 of the arc segment is 88 - 92 and the arc length is 14 - 16, and the length L7 of the second straight line segment is 9.4 - 10.6.

[0014] Further, the diameter φ4 of the air suction port is 425, the length L6 of the first straight line segment is 6, the radius R6 of the arc segment is 90 and the arc length is 14.82, and the length L7 of the second straight line segment is 10.

[0015] Further, the collector includes a connecting portion, a flaring portion, an air inlet, and a guiding air port. The collector is fixedly connected to the volute through the connecting portion, and the flaring portion partially extends into the inner cavity of the volute;

[0016] The collector is intercepted by a plane passing through the central axis of the collector. On the cross-section, the flaring part includes a first flaring straight segment, a first flaring arc segment, a second flaring straight segment, and a second flaring arc segment that are connected in sequence. The first flaring straight segment is annular and forms an air inlet on its inner circumference. The diameter φ5 of the air inlet is 425 - 427.5. The diameter of the flaring part first gradually decreases and then gradually increases in the direction away from the first flaring straight segment. The radius R7 of the first flaring arc segment is 19 - 21 and the arc length is 22 - 24.5. The length L11 of the second flaring straight segment is 96 - 98.4. The radius R8 of the second flaring arc segment is 73.5 - 76.5 and the arc length is 128 - 133.6. The diameter φ6 at the narrowest part of the flaring part is 299 - 301. One end of the second flaring arc segment away from the air inlet forms an air guiding port. The diameter φ7 of the air guiding port is 403 - 405. The vertical distance L9 between the narrowest part of the flaring part and the air inlet is 130 - 132. The vertical distance L13 between the narrowest part of the flaring part and the air guiding port is 72 - 74. The length L10 of the flaring part extending into the volute is 29.2 - 30.8.

[0017] Further, the diameter φ5 of the air inlet is 426.3, the radius R7 of the first flaring arc segment is 20 and the arc length is 23.2, the length L11 of the second flaring straight segment is 97.2, the radius R8 of the second flaring arc segment is 75 and the arc length is 130.8, the diameter φ6 at the narrowest part of the flaring part is 300, one end of the second flaring arc segment away from the air inlet forms an air guiding port, the diameter φ7 of the air guiding port is 404, the vertical distance L9 between the narrowest part of the flaring part and the air inlet is 131, the vertical distance L13 between the narrowest part of the flaring part and the air guiding port is 73, and the length L10 of the flaring part extending into the volute is 30.

[0018] Further, the profile line of the volute includes a first diffusing straight segment, a volute tongue segment, a first arc segment, a second arc segment, a third arc segment, and a second diffusing straight segment that are tangent to each other in sequence; the first diffusing straight segment and the second diffusing straight segment enclose an air outlet, and the first arc segment, the second arc segment, and the third arc segment are not concentric.

[0019] Taking the center of the impeller as the coordinate origin to establish a rectangular coordinate system, when the first diffusing straight segment is in the third quadrant, the coordinates of the center O1 of the first arc segment are (21.9, 21.9), the radius R2 is 313 - 318.2 and the arc length is 688 - 692.5, the coordinates of the center O2 of the second arc segment are (21.9, -21.9), the radius R3 is 357.4 - 361.4 and the arc length is 563 - 566, the coordinates of the center O3 of the third arc segment are (-21.9, -21.9), the radius R4 is 402 - 405 and the arc length is 631.7 - 634.7, and the first diffusing straight segment is parallel to the second diffusing straight segment.

[0020] Further, a rectangular coordinate system is established with the center of the impeller as the coordinate origin. When the first diffuser straight section is located in the third quadrant, the center O1 of the first arc segment has coordinates (21.9, 21.9), the radius R2 is 315.6, and the arc length is 690.3. The center O2 of the second arc segment has coordinates (21.9, -21.9), the radius R3 is 359.4, and the arc length is 564.5. The center O3 of the third arc segment has coordinates (-21.9, -21.9), the radius R4 is 403.1, and the arc length is 633.2.

[0021] Further, the height L4 of the air outlet is 224 - 226, and the width L3 is 174 - 176;

[0022] The radius R1 of the volute tongue section is 24 - 26, and the arc length is 53.8 - 55.6. The length L1 of the first diffuser straight section is 78 - 80, and the length L2 of the second diffuser straight section is 310 - 316. A tangent is drawn to the volute tongue section with the tangent point of the volute tongue section and the first arc segment as the tangent point, and the angle ∠1 between this tangent and the first diffuser straight section is 53° - 56.4°.

[0023] Further, the height L4 of the air outlet is 225, and the width L3 is 175;

[0024] The radius R1 of the volute tongue section is 25, and the arc length is 54.7. The length L1 of the first diffuser straight section is 79, and the length L2 of the second diffuser straight section is 313.1. A tangent is drawn to the volute tongue section with the tangent point of the volute tongue section and the first arc segment as the tangent point, and the angle ∠1 between this tangent and the first diffuser straight section is 54.69°.

[0025] A centrifugal ventilator for agricultural seeding machinery provided by the present invention:

[0026] (1) It adopts sheet metal large blades designed with straight blade parts and curved blade parts, designs a circular arc leading edge structure, and designs two small blades between adjacent large blades. The straight blade part can guide the airflow, control the airflow direction, accelerate the flow field between the blades, optimize the pressure loss between the blades, suppress the blade tip vortex and the airflow disturbance at the blade inlet angle, improve the pressure loss caused by first accelerating and then decelerating, increase the effective flow range of the fan, the fan efficiency, and optimize the aerodynamic performance of the fan;

[0027] (2) By reasonably designing the radial clearance between the collector and the front disc of the impeller, the impact flow loss in the internal flow field of the fan is reduced, the fan efficiency is improved, the fan noise is reduced, the stability of the flow field at the fan inlet is enhanced, and the problems of the air flow reacting force on the impeller when the distance between the two is too short, the air flow being interrupted when the distance between the two is too long, generating eddy currents, and further reducing the fan efficiency and increasing the noise are solved. The collector adopts an air inlet design with a conical contraction followed by an arc expansion, enabling the air flow to enter the impeller more smoothly, suppressing eddy currents, improving the fan energy efficiency, and further reducing the fan noise;

[0028] (3) The volute profile designed with an equilateral primitive enables the internal flow field of the fan to flow uniformly; through the design of the air outlet, a reasonable air velocity is obtained at the air outlet, the ratio of the outlet dynamic pressure and the inlet static pressure is balanced, and the fan obtains higher efficiency. Brief Description of the Drawings

[0029] Figure 1 It is a schematic structural diagram of the centrifugal fan for agricultural seeding machinery of the present invention;

[0030] Figure 2 It is a schematic diagram of the volute profile;

[0031] Figure 3 It is a partially sectioned side view of the volute;

[0032] Figure 4 It is a schematic structural diagram of the impeller;

[0033] Figure 5 It is a schematic side view structure diagram of the impeller;

[0034] Figure 6 It is a side view sectional view of the collector;

[0035] Figure 7 It is a schematic structural diagram of the centrifugal fan for agricultural seeding machinery in the prior art;

[0036] Figure 8 It is a performance curve graph of the centrifugal fan for agricultural seeding machinery of the present invention;

[0037] Figure 9 It is a performance curve graph of the centrifugal fan for agricultural seeding machinery in the prior art.

[0038] Explanation of the Reference Numerals:

[0039] Volute 1; First diffuser straight section 11; Volute tongue section 12; First arc section 13; Second arc section 14; Third arc section 15; Second diffuser straight section 16; Air outlet 17;

[0040] Impeller 2; large blade 21; leading edge 211; first straight segment 2111; arc segment 2112; second straight segment 2113; trailing edge 212; straight blade part 213; curved blade part 214; front disc 22; rear disc 23; air suction port 24; small blade 25;

[0041] Air collector 3; connecting part 31; flaring part 32; first flaring straight segment 321; first flaring arc segment 322; second flaring straight segment 323; second flaring arc segment 324; air inlet 33; air guiding port 34. Specific implementation mode

[0042] The present invention will be described in detail below in conjunction with specific embodiments.

[0043] In the present invention, unless otherwise clearly specified and limited, when terms such as "arranged on", "connected", "connected" appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection or an integral connection; it can be directly connected or connected through one or more intermediate media. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations. For the direction words in the present invention, they are used to better explain the characteristics and the relationships between the characteristics. It should be understood that when the placement direction of the present invention changes, the directions of the characteristics and the relationships between the characteristics also change correspondingly. Therefore, the direction words do not constitute an absolute limiting effect on the characteristics and the relationships between the characteristics in space, but only play a relative limiting role.

[0044] The present invention uses a dimensionless method to describe the structural parameters of the centrifugal ventilator for agricultural seeding machinery. That is, based on this dimensionless basic structure, reasonable equal-proportion scaling can be carried out during actual production (for example, when the diameter of the outer peripheral circle formed by the outermost ends of multiple blades is 500 mm, it can be scaled by 0.1 - 30 times, etc.). This reasonable equal-proportion scaling also falls within the protection scope of the present invention.

[0045] Please refer to Figures 1-6 , a centrifugal ventilator for agricultural seeding machinery, including a volute 1, an impeller 2 and an air collector 3. The volute 1 and the air collector 3 are fixedly connected, and the impeller 2 is arranged in the volute 1; the impeller 2 includes a front disc 22 and a rear disc 23. An air suction port 24 is arranged in the middle of the front disc 22, and a plurality of blades are arranged in a circumferential array on the rear disc 23;

[0046] The blades are of sheet metal structure. The blades include large blades 21 and small blades 25. Two small blades 25 are arranged between two adjacent large blades 21, and the quantity ratio of the large blades 21 to the small blades 25 is 1:2;

[0047] The large blade 21 includes a straight blade portion 213, a curved blade portion 214, an arc-shaped leading edge 211 disposed at the front end of the straight blade portion 213, a trailing edge 212 disposed at the end of the curved blade portion 214, a first side connected between the first ends of the leading edge 211 and the trailing edge 212, and a second side connected between the second ends of the leading edge 211 and the trailing edge 212. The first side is the side close to the air suction port 24, and the second side is the side away from the air suction port 24. The leading edge 211 includes a first straight segment 2111, an arc segment 2112, and a second straight segment 2113 connected in sequence. The first straight segment 2111 is connected to the first side, and the second straight segment 2113 is connected to the second side. The leading edge 211 is inclined from the first straight segment 2111 to the second straight segment 2113 in the direction of the axle of the impeller 2;

[0048] In dimensionless terms, the outlet angle ∠2 of the large blade 21 during installation is 166° - 170°. On the projection plane of the rear disc 23, the length L5 of the straight blade portion 213 is 112 - 115, the radius R5 of the curved blade portion 214 and the small blade 25 is 28.8 - 30.3, and the arc length is 48.7 - 51.3;

[0049] The diameter φ1 of the outer peripheral circle formed by the outer ends of all the blades of the impeller 2 is 495 - 505, the diameter φ2 of the inner peripheral circle formed by the inner ends of all the small blades 25 is 428 - 434, the diameter φ3 of the inner peripheral circle formed by the inner ends of all the large blades 21 is 199 - 201, and the width L8 of the trailing edge 212 is 104.5 - 107.5. A radial clearance L12 is provided between the collector 3 and the impeller 2, and L12 is 4.5 - 5.5. Preferably, ∠2 is 168°, L5 is 113.6, R5 is 29.5 and the arc length is 50, φ1 is 500, φ2 is 430.9, φ3 is 200, L8 is 106, L12 is 5; the number of large blades 21 is 16, and the number of small blades 25 is 32.

[0050] Through the above technical solutions, (1) the sheet metal large blade 21 designed with the straight blade part 213 and the curved blade part 214 has an arc-shaped leading edge 211 structure. Two small blades 25 are designed between adjacent large blades 21. The straight blade part 213 can divert the air flow, which can not only control the air flow direction but also accelerate the flow field between the blades, so as to optimize the pressure loss between the blades, suppress the blade tip vortex and the air flow disturbance at the blade inlet angle, improve the pressure loss caused by the initial acceleration and subsequent deceleration, increase the effective flow range of the fan, improve the fan efficiency and optimize the aerodynamic performance of the fan; (2) by reasonably designing the radial clearance between the air collector 3 and the front disc 22 of the impeller, the impact flow loss in the internal flow field of the fan is reduced, the fan efficiency is improved, the fan noise is reduced, the stability of the flow field at the fan inlet is improved, and the problems that when the distance between them is too short, an air flow reaction force is generated on the impeller 2, and when the distance between them is too long, the air flow is interrupted to generate eddy currents, thereby reducing the fan efficiency and causing excessive noise are solved.

[0051] In this embodiment, the impeller 2 is intercepted by a plane passing through the central axis of the impeller 2. On the cross section, the diameter φ4 of the air suction port 24 is 422 - 428, the length L6 of the first straight line segment 2111 is 5.5 - 6.5, the radius R6 of the arc segment 2112 is 88 - 92 and the arc length is 14 - 16, and the length L7 of the second straight line segment 2113 is 9.4 - 10.6. Preferably, the diameter φ4 of the air suction port 24 is 425, the length L6 of the first straight line segment 2111 is 6, the radius R6 of the arc segment 2112 is 90 and the arc length is 14.82, and the length L7 of the second straight line segment 2113 is 10.

[0052] In this embodiment, the air collector 3 includes a connecting part 31, a flaring part 32, an air inlet 33 and an air guiding port 34. The air collector 3 is fixedly connected to the volute 1 through the connecting part 31, and a part of the flaring part 32 extends into the inner cavity of the volute 1;

[0053] The collector 3 is intercepted by a plane passing through the central axis of the collector 3. On the cross-section, the flaring part 32 includes a first flaring straight segment 321, a first flaring arc segment 322, a second flaring straight segment 323, and a second flaring arc segment 324 that are sequentially connected. The first flaring straight segment 321 is in a circular ring shape and an air inlet 33 is formed on its inner circumference. The diameter φ5 of the air inlet 33 is 425 - 427.5. The diameter of the flaring part 32 first gradually decreases and then gradually increases in the direction away from the first flaring straight segment 321. The radius R7 of the first flaring arc segment 322 is 19 - 21 and the arc length is 22 - 24.5. The length L11 of the second flaring straight segment 323 is 96 - 98.4. The radius R8 of the second flaring arc segment 324 is 73.5 - 76.5 and the arc length is 128 - 133.6. The diameter φ6 at the narrowest part of the flaring part 32 is 299 - 301. One end of the second flaring arc segment 324 away from the air inlet 33 forms an air guiding port 34. The diameter φ7 of the air guiding port 34 is 403 - 405. The vertical distance L9 between the narrowest part of the flaring part 32 and the air inlet 33 is 130 - 132. The vertical distance L13 between the narrowest part of the flaring part 32 and the air guiding port 34 is 72 - 74. The length L10 of the flaring part 32 extending into the volute 1 is 29.2 - 30.8.

[0054] Preferably, the diameter φ5 of the air inlet 33 is 426.3, the radius R7 of the first flaring arc segment 322 is 20 and the arc length is 23.2, the length L11 of the second flaring straight segment 323 is 97.2, the radius R8 of the second flaring arc 324 segment is 75 and the arc length is 130.8, the diameter φ6 at the narrowest part of the flaring part 32 is 300, one end of the second flaring arc segment 324 away from the air inlet 33 forms an air guiding port 34, the diameter φ7 of the air guiding port 34 is 404, the vertical distance L9 between the narrowest part of the flaring part 32 and the air inlet 33 is 131, the vertical distance L13 between the narrowest part of the flaring part 32 and the air guiding port 34 is 73, and the length L10 of the flaring part 32 extending into the volute 1 is 30.

[0055] Through the above technical solution, in cooperation with the improvements of the impeller 2 and the volute 1, the collector 3 adopts an air inlet design with a tapered contraction followed by an arc expansion, enabling the air flow to enter the impeller 2 more smoothly. The straight blade part 213 of the flow channel is configured as a rectifying grid for rectification, suppressing eddy currents, improving the energy efficiency of the fan, and further reducing the noise of the fan.

[0056] In this embodiment, the profile line of the volute 1 includes a first diffusing straight segment 11, a volute tongue segment 12, a first arc segment 13, a second arc segment 14, a third arc segment 15, and a second diffusing straight segment 16 that are sequentially tangent and connected; the first diffusing straight segment 11 and the second diffusing straight segment 16 enclose an air outlet 17, and the first arc segment 13, the second arc segment 14, and the third arc segment 15 are not concentric;

[0057] Taking the center of the impeller 2 as the origin of the coordinate system to establish a rectangular coordinate system. When the first diffuser straight line segment 11 is in the third quadrant, the coordinates of the center O1 of the first arc segment 13 are (21.9, 21.9), the radius R2 is 313 - 318.2, and the arc length is 688 - 692.5. The coordinates of the center O2 of the second arc segment 14 are (21.9, -21.9), the radius R3 is 357.4 - 361.4, and the arc length is 563 - 566. The coordinates of the center O3 of the third arc segment 15 are (-21.9, -21.9), the radius R4 is 402 - 405, and the arc length is 631.7 - 634.7. The first diffuser straight line segment 11 is parallel to the second diffuser straight line segment 16.

[0058] Preferably, taking the center of the impeller 2 as the origin of the coordinate system to establish a rectangular coordinate system. When the first diffuser straight line segment 11 is in the third quadrant, the coordinates of the center O1 of the first arc segment 13 are (21.9, 21.9), the radius R2 is 315.6, and the arc length is 690.3. The coordinates of the center O2 of the second arc segment 14 are (21.9, -21.9), the radius R3 is 359.4, and the arc length is 564.5. The coordinates of the center O3 of the third arc segment 15 are (-21.9, -21.9), the radius R4 is 403.1, and the arc length is 633.2.

[0059] In this embodiment, the height L4 of the air outlet 17 is 224 - 226, and the width L3 is 174 - 176;

[0060] The radius R1 of the volute tongue section 12 is 24 - 26, and the arc length is 53.8 - 55.6. The length L1 of the first diffuser straight line segment 11 is 78 - 80, and the length L2 of the second diffuser straight line segment 16 is 310 - 316. Taking the tangent point of the volute tongue section 12 and the first arc segment 13 as the tangent point to make a tangent to the volute tongue section 12, the included angle ∠1 between this tangent and the first diffuser straight line segment 11 is 53° - 56.4°. It should be noted that in the volute 1, adjacent arc segments are all set to be tangent to each other, that is, the volute tongue section 12 is tangent to the first arc segment 13, the first arc segment 13 is tangent to the second arc segment 14, and the second arc segment 14 is tangent to the third arc segment 15. When making a tangent with the tangent point of adjacent arc segments as the tangent point, this tangent is tangent to these two adjacent arc segments.

[0061] Preferably, the height L4 of the air outlet 17 is 225, and the width L3 is 175;

[0062] The radius R1 of the volute tongue section 12 is 25, and the arc length is 54.7. The length L1 of the first diffuser straight line segment 11 is 79, and the length L2 of the second diffuser straight line segment 16 is 313.1. Taking the tangent point of the volute tongue section 12 and the first arc segment 13 as the tangent point to make a tangent to the volute tongue section 12, the included angle ∠1 between this tangent and the first diffuser straight line segment 11 is 54.69°.

[0063] Through the above technical solution, the spiral casing 1 profile designed with equilateral elements enables the fluid field inside the spiral casing 1 to flow evenly; through the design of the air outlet 17, a reasonable wind speed is obtained at the air outlet 17, the ratio of the dynamic pressure at the outlet and the static pressure at the inlet is balanced, and in combination with the improvements to the impeller 2 and the collector 3, the fan obtains higher efficiency.

[0064] For the verification of this embodiment, Figure 7 the centrifugal fan used in the prior art shown in 3 is taken as the comparative example, and the impeller diameter is 500 mm; based on the preferred structural parameters provided in this embodiment, and with the diameter of the impeller 2 (i.e., the outer peripheral circle diameter formed by the outermost ends of multiple blades) being 500 mm, a centrifugal fan for agricultural seeding machinery of the present invention is prepared as the test example for testing. The test results are converted into test data under the test conditions of an atmospheric pressure of 101325 Pa, an atmospheric temperature of 20 °C, a fan speed of 1450 r / min, and a medium density of 1.2 kg / m Figure 8 to obtain the test data of the test example shown in Table 1 and Figure 9 the performance curve shown in

[0065] Table 1

[0066]

[0067] Table 2

[0068]

[0069] It can be seen from the test data and performance curves that in the test example, the total pressure range of the fan is 1725.6 Pa - 2328.1 Pa, the effective flow rate range of the fan is 2109.5 m³ / h - 8489.1 m³ / h, the highest point of the fan efficiency is 70.784%, and the A-weighted sound level is 82.161 at this time. In the comparative example, the total pressure range of the fan is 1660.8 Pa - 2129.7 Pa, the effective flow rate range of the fan is 1747.1 m³ / h - 6610.0 m³ / h, the highest point of the fan efficiency is 64.500%, and the A-weighted sound level is 90.501 at this time. Further, at the same or similar total pressure, such as when the total pressure in the test example is 2203.8 Pa and the total pressure in the comparative example is 2206.4 Pa, the fan flow rate in the test example is 6641.0 m³ / h, while the fan flow rate in the comparative example is 5136.7 m³ / h, the fan efficiency in the test example is 66.751%, while the fan efficiency in the comparative example is 64.303%, the noise in the test example is 84.676 dB, while the noise in the comparative example is 88.263 dB. In summary, compared with the centrifugal fan used in agricultural seeding machinery in the prior art, the total pressure of the centrifugal fan for agricultural seeding machinery of the present invention is increased, the volumetric flow rate is larger, the fan efficiency is higher, it can effectively control the seeding speed and distance, and the fan noise is lower, improving the seeding environment.

[0070] Compared with the prior art, the total pressure of the centrifugal fan for agricultural seeding machinery of the present invention is increased, the volumetric flow rate is larger, the fan efficiency is higher, and the fan noise is lower, achieving the effects of improving the fan efficiency, increasing the fan flow rate range, and reducing the noise, and can effectively control the seeding speed and distance, improving the seeding environment.

[0071] Without conflict, the above-mentioned embodiments and the features in the embodiments can be combined with each other.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A centrifugal fan for agricultural sowing machinery, comprising a volute, an impeller and a collector, wherein the volute and the collector are fixedly connected, and the impeller is arranged in the volute; the impeller comprises a front disc and a rear disc, wherein a suction port is arranged in the middle of the front disc, and a plurality of blades are arranged in an array around the rear disc, and the characteristics are as follows: The blade is a sheet metal structure, and includes a large blade and a small blade. Two small blades are arranged between two adjacent large blades, and the ratio of the number of large blades to the number of small blades is 1:2; The large blade includes a straight blade portion, a curved blade portion, an arc-shaped leading edge arranged at the front end of the straight blade portion, a trailing edge arranged at the end of the curved blade portion, a first side edge connected between the first ends of the leading edge and the trailing edge, and a second side edge connected between the second ends of the leading edge and the trailing edge, the first side edge is a side edge close to the air suction port, the second side edge is a side edge away from the air suction port, the leading edge includes a first straight line segment, an arc segment, and a second straight line segment connected in sequence, the first straight line segment is connected to the first side edge, the second straight line segment is connected to the second side edge, and the leading edge is inclined along the first straight line segment toward the second straight line segment toward the direction of the wheel shaft of the impeller; In dimensionless terms, the outlet angle ∠2 when the large blade is installed is 166°-170°. On the projection surface of the rear disc, the length L5 of the straight blade is 112-115, the radius R5 of the curved blade and the small blade is 28.8-30.3 and the arc length is 48.7-51.3; The diameter φ1 of the outer circle formed by the outer ends of all blades of the impeller is 495-505, the diameter φ2 of the inner circle formed by the inner ends of all small blades is 428-434, the diameter φ3 of the inner circle formed by the inner ends of all large blades is 199-201, and the width L8 of the trailing edge is 104.5-107.5; A radial clearance L12 is provided between the collector and the impeller, and L12 is 4.5-5.5; The collector includes a connecting portion, a flaring portion, an air inlet and an air guide port. The collector is fixedly connected to the volute through the connecting portion, and the flaring portion partially extends into the inner cavity of the volute. The collector is intercepted by a plane passing through the central axis of the collector. In the cross section, the flared portion includes a first flared straight line segment, a first flared arc segment, a second flared straight line segment and a second flared arc segment which are sequentially connected. The first flared straight line segment is annular and an air inlet is formed on the inner circumference. The diameter φ5 of the air inlet is 425-427.

5. The diameter of the flared portion gradually decreases and then gradually increases in the direction away from the first flared straight line segment. The radius R7 of the first flared arc segment is 19-21 and the arc length is 22-24.

5. The length of the second flared straight line segment is φ6. L11 is 96-98.4, the radius R8 of the second flared arc segment is 73.5-76.5 and the arc length is 128-133.6, the diameter φ6 of the narrowest part of the flared portion is 299-301, and an air guide port is formed at the end of the second flared arc segment away from the air inlet, the diameter φ7 of the air guide port is 403-405, the vertical distance L9 between the narrowest part of the flared portion and the air inlet is 130-132, the vertical distance L13 between the narrowest part of the flared portion and the air guide port is 72-74, and the length L10 of the flared portion extending into the volute is 29.2-30.

8.

2. A centrifugal fan for agricultural sowing machinery according to claim 1, characterized in that: ∠2 is 168°, L5 is 113.6, R5 is 29.5 and the arc length is 50, φ1 is 500, φ2 is 430.9, φ3 is 200, L8 is 106, and L12 is 5; There are 16 large leaves and 32 small leaves.

3. A centrifugal fan for agricultural sowing machinery according to claim 1, characterized in that: The impeller is cut with a plane passing through the central axis of the impeller. In the cross section, the diameter φ4 of the air intake port is 422-428, the length L6 of the first straight line segment is 5.5-6.5, the radius R6 of the arc segment is 88-92 and the arc length is 14-16, and the length L7 of the second straight line segment is 9.4-10.

6.

4. A centrifugal fan for agricultural sowing machinery according to claim 3, characterized in that: The diameter φ4 of the air suction port is 425, the length L6 of the first straight line segment is 6, the radius R6 of the arc segment is 90 and the arc length is 14.82, and the length L7 of the second straight line segment is 10.

5. The centrifugal fan for agricultural sowing machinery according to claim 1, characterized in that: The diameter φ5 of the air inlet is 426.3, the radius R7 of the first expansion arc segment is 20 and the arc length is 23.2, the length L11 of the second expansion straight line segment is 97.2, the radius R8 of the second expansion arc segment is 75 and the arc length is 130.8, the diameter φ6 of the narrowest part of the expansion part is 300, and an air guide port is formed at the end of the second expansion arc segment away from the air inlet, the diameter φ7 of the air guide port is 404, the vertical distance L9 between the narrowest part of the expansion part and the air inlet is 131, the vertical distance L13 between the narrowest part of the expansion part and the air guide port is 73, and the length L10 of the expansion part extending into the volute is 30.

6. A centrifugal fan for agricultural seeding machinery according to claim 1, characterized in that: The profile of the volute includes a first diffuser straight line segment, a volute tongue segment, a first arc segment, a second arc segment, a third arc segment and a second diffuser straight line segment which are tangentially connected in sequence; the first diffuser straight line segment and the second diffuser straight line segment enclose an air outlet, and the first arc segment, the second arc segment and the third arc segment are not co-centered; A rectangular coordinate system is established with the center of the impeller as the coordinate origin. When the first diffuser straight line segment is located in the third quadrant, the coordinates of the center O1 of the first arc segment are (21.9, 21.9), the radius R2 is 313-318.2, and the arc length is 688-692.

5. The coordinates of the center O2 of the second arc segment are (21.9, -21.9), the radius R3 is 357.4-361.4, and the arc length is 563-566. The coordinates of the center O3 of the third arc segment are (-21.9, -21.9), the radius R4 is 402-405, and the arc length is 631.7-634.

7. The first diffuser straight line segment is parallel to the second diffuser straight line segment.

7. A centrifugal fan for agricultural seeding machinery according to claim 6, characterized in that: A rectangular coordinate system is established with the center of the impeller as the coordinate origin. When the first diffuser straight line segment is located in the third quadrant, the coordinates of the center O1 of the first arc segment are (21.9, 21.9), the radius R2 is 315.6 and the arc length is 690.

3. The coordinates of the center O2 of the second arc segment are (21.9, -21.9), the radius R3 is 359.4 and the arc length is 564.

5. The coordinates of the center O3 of the third arc segment are (-21.9, -21.9), the radius R4 is 403.1 and the arc length is 633.

2.

8. A centrifugal fan for agricultural seeding machinery according to claim 7, characterized in that: The height L4 of the air outlet is 224-226, and the width L3 is 174-176; The radius R1 of the volute tongue segment is 24-26 and the arc length is 53.8-55.6, the length L1 of the first diffuser straight line segment is 78-80, the length L2 of the second diffuser straight line segment is 310-316, and a tangent 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 ∠1 between the tangent and the first diffuser straight line segment is 53°-56.4°.

9. A centrifugal fan for agricultural sowing machinery according to claim 8, characterized in that: The height L4 of the air outlet is 225 and the width L3 is 175; The radius R1 of the volute tongue segment is 25 and the arc length is 54.7, the length L1 of the first diffuser straight line segment is 79, the length L2 of the second diffuser straight line segment is 313.1, and a tangent 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 ∠1 between the tangent and the first diffuser straight line segment is 54.69°.

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