Impurity removal fan and impurity removal system for corn harvester and corn harvester

Abstract

The utility model relates to the technical field of agricultural machinery, and discloses an impurity removal fan for a corn harvester, an impurity removal system and the corn harvester. The impurity removal fan comprises a fan shell, a transmission shaft and an impeller; the transmission shaft is rotatably arranged on the fan shell; the impeller is arranged on the transmission shaft and comprises a plurality of spiral fan blades; a normal plane is taken along a rotating shaft of the spiral fan blade, from the direction of the normal plane, the rotating direction of the spiral fan blade serves as the positive direction, otherwise, the rotating direction of the spiral fan blade serves as the negative direction, an intersection line of the normal plane and the spiral fan blade serves as a blade generatrix, the blade generatrix is in the shape of a multi-section arc line with continuous slopes, the curvature of the arc line section close to the axis is positive, and the curvature of the arc line section away from the axis is negative. According to the impurity removal fan, the problem that the fan is prone to being blocked when many impurities exist can be effectively solved, the impurity removal efficiency is improved, and energy consumption is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of agricultural machinery, and particularly relates to a corn harvester impurity removal fan, an impurity removal system and a corn harvester. BACKGROUND

[0002] In the corn harvesting process, the impurity removal fan is one of the key components, which mainly functions to remove the impurities (such as corn leaves, straws, bracts, etc.) generated in the corn harvesting process, so as to reduce the working load of the peeling machine and improve the harvesting efficiency and quality.

[0003] However, the prior art uses a flat blade, an arc-shaped blade with a single curvature direction, to perform air suction and impurity removal, and the shape of the blade along the axial direction is flat. In this way, the following disadvantages exist:

[0004] Low impurity removal efficiency: the flat blade and the arc-shaped blade with a single curvature direction have a much higher air outlet speed than air inlet speed during impurity removal, and the wind field distribution is thus uneven, which cannot effectively absorb and remove the impurities and is prone to idling, and cannot solve the problem of blockage of the elevator. Prone to blockage: due to the uneven wind field distribution, the impurities are thrown out of the fan before entering the innermost side of the blade, so that the utilization rate of the outer side of the blade is low, and the impurities accumulated on the inner side are prone to blockage, affecting the normal operation of the fan. High energy consumption: in order to achieve a certain impurity removal effect, the existing fan needs higher speed and greater power or wider blades, which increases energy consumption. CONTENT OF THE INVENTION

[0005] The application aims to provide a corn harvester impurity removal fan, an impurity removal system and a corn harvester, to solve the problems of low impurity removal efficiency, blockage and high energy consumption of the existing impurity removal fan.

[0006] In order to achieve the above-mentioned purpose, the application provides a corn harvester impurity removal fan in the first aspect, which comprises:

[0007] a fan housing;

[0008] a transmission shaft rotatably arranged on the fan housing; and

[0009] a impeller arranged on the transmission shaft, the impeller comprising a plurality of spiral vanes;

[0010] wherein, along the rotation axis of the spiral vane, a tangent plane is taken, viewed from the tangent plane direction, the rotation direction of the spiral vane is taken as the positive direction, and vice versa, the intersection line between the tangent plane and the spiral vane is a blade generatrix, and the shape of the blade generatrix is a plurality of arc lines with continuous slopes, the curvature of the arc line segment close to the axis of the transmission shaft (200) is positive, and the curvature of the arc line segment away from the axis of the transmission shaft (200) is negative.

[0011] As a further improvement of the above technical solution,

[0012] In some embodiments, the shape of the vane generatrix is a multi-segment circular arc line with continuous slope.

[0013] In some embodiments, the curvature of the circular arc segment close to the axis of the transmission shaft (200) is positive, and the curvature of the circular arc segment away from the axis of the transmission shaft (200) is negative.

[0014] In some embodiments, the shape of the vane generatrix is a two-segment circular arc line with continuous slope, which includes a first circular arc segment and a second circular arc segment.

[0015] In some embodiments, the first circular arc segment is close to the axis of the transmission shaft (200) and has positive curvature, and the second circular arc segment is away from the axis of the transmission shaft (200) and has negative curvature.

[0016] In some embodiments, a point in the vane generatrix with a curvature of 0 is defined as N, and the length of the line segment from the N point to the outer surface of the transmission shaft in the radial direction to the outside of the spiral fan is L.

[0017] In some embodiments, the distance from the N point to the outer surface of the transmission shaft is L1, the distance from the N point to the outside of the spiral fan is L2, and L1:L2=0.34~0.46.

[0018] In some embodiments, a point in the vane generatrix with a curvature of 0 is defined as N, and the length of the line segment from the N point to the outer surface of the transmission shaft in the radial direction to the outside of the spiral fan is L, and the width of the spiral fan is H.

[0019] In some embodiments, the distance from the N point to the outer surface of the transmission shaft is L1, the distance from the N point to the outside of the spiral fan is L2, and L1:L2=0.34~0.46.

[0020] In some embodiments, a point where the vane generatrix intersects with the outer circle of the transmission shaft is defined as O, a point on the outermost side of the vane generatrix is defined as M, a point in the vane generatrix with a curvature of 0 is defined as N, and the vane generatrix also has a point A.

[0021] In some embodiments, the angle between the tangent line of the vane generatrix at point A and the radial line passing through point O is θ, when point A coincides with point O, θ is greater than 0 degrees, when point A moves along the vane generatrix from point O to point N, θ gradually increases, and when point A moves along the vane generatrix from point N to point M, θ gradually decreases.

[0022] In some embodiments, the helical line around the transmission shaft on which the spiral fan rotates is the helical guide line of the spiral fan, and the ratio of the helical pitch of the helical guide line to the width of the spiral fan and the radius of revolution of the spiral fan is inversely proportional.

[0023] In some embodiments, the fan housing is provided with a reserved air inlet and a reserved air outlet.

[0024] The second aspect of the present application provides a corn harvester impurity removal system, comprising the corn harvester impurity removal fan provided in the first aspect.

[0025] The third aspect of the present application provides a corn harvester, comprising the corn harvester impurity removal system provided in the second aspect.

[0026] Compared with the prior art, the present application provides a corn harvester impurity removal fan, an impurity removal system and a corn harvester, which have the following beneficial effects:

[0027] The impeller of the corn harvester impurity removal fan provided in the present application comprises a plurality of spiral vanes, the blade generatrix of each spiral vane is in the shape of a plurality of arc lines with continuous slopes, the curvature of the arc line segment close to the axis of the transmission shaft is positive, and the curvature of the arc line segment away from the axis of the transmission shaft is negative. In this way, since the curvature of the arc line segment close to the axis of the transmission shaft is positive, the arc line of the blade generatrix close to the transmission shaft of the spiral vane is convex forward, the relative speed of the impurities and the blade is backward and the absolute speed is forward during the radial movement of the impurities, the speed difference between the impurities and the blade at the inlet is reduced, the running impact is reduced, and the flow of the impurities is smoother; since the curvature of the arc line segment away from the axis of the transmission shaft is negative, the arc line of the blade generatrix away from the transmission shaft of the spiral vane is concave backward, a larger high-pressure area space is reserved, and there is still enough space to retain high-pressure air in the case of more impurities, which ensures the ability of the fan to maintain the maximum static pressure, effectively avoids the problem that the fan is easily blocked when there are more impurities, improves the impurity removal efficiency, and reduces the energy consumption.

[0028] In addition, the axial spiral of the spiral vane can push the impurities to move axially into the inside of the spiral vane during the radial movement of the impurities, which reduces the speed difference between the axial movement and the radial movement of the material of the wide-blade fan, and effectively avoids the problem that the inside of the spiral vane of the wide-blade fan has low utilization rate.

[0029] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0030] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, and are used together with the following specific embodiments to explain the present application, but do not constitute a limitation on the present application. For those skilled in the art, other drawings can be obtained from the structures shown in the drawings without creative labor. In the drawings:

[0031] Figure 1A partial structural schematic diagram of a dust removal fan for a corn harvester provided in an embodiment of this application;

[0032] Figure 2 for Figure 1 The image shows the front view of the dust removal fan used in a corn harvester.

[0033] Figure 3 for Figure 1 The image shows a top view of a corn harvester with its exhaust fan concealed.

[0034] Explanation of reference numerals in the attached figures

[0035] 100. Fan casing; 110. Reserved air inlet; 120. Reserved air outlet;

[0036] 200. Drive shaft;

[0037] 300, Impeller; 310, Helical fan blade; 311, Blade generatrix; 311a, First circular arc segment; 311b, Second circular arc; 312, Helical conductor; 312a, Inner helical conductor; 312b, Outer helical conductor;

[0038] V1 is the rotation direction of the spiral fan blades; V2 is the direction of waste entering; V3 is the direction of waste exiting. Detailed Implementation

[0039] The specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0040] The present application will now be described in detail with reference to the accompanying drawings and exemplary embodiments.

[0041] Example 1

[0042] Please see Figure 1 and Figure 2 This embodiment provides a dust removal fan for a corn harvester, hereinafter referred to as the dust removal fan. The main function of the dust removal fan is to remove the debris (such as corn leaves, stalks, husks, etc.) generated during the corn harvesting process, so as to reduce the workload of the peeling machine and improve harvesting efficiency and quality.

[0043] The exhaust fan provided in this embodiment includes: a fan housing 100, a drive shaft 200, and an impeller 300; the drive shaft 200 is rotatably mounted on the fan housing 100 and is used for drive connection with a motor; the impeller 300 is mounted on the drive shaft 200 and includes multiple spiral blades 310, which can also be understood as a three-dimensional twisted blade shape.

[0044] The fan shell 100 is provided with a reserved air inlet 110 and a reserved air outlet 120.

[0045] In the embodiment, a tangent plane is taken along the rotation axis of the spiral fan blade 310, and the spiral fan blade 310 is taken as a positive direction in the direction of the tangent plane, and vice versa. The intersection line between the tangent plane and the spiral fan blade 310 is a blade generatrix 311. The shape of the blade generatrix 311 is a plurality of arc lines with continuous slopes. The curvature of the arc line segment close to the axis of the transmission shaft 200 is positive, and the curvature of the arc line segment away from the axis of the transmission shaft 200 is negative.

[0046] Further, the shape of the blade generatrix 311 is a plurality of circular arc lines with continuous slopes. The curvature of the circular arc segment close to the axis is positive, and the curvature of the circular arc segment away from the axis is negative. It can be understood that the circular arc line structure is convenient for processing and manufacturing, and reduces production cost.

[0047] It should be noted that the existing impurity removal fan uses flat blades, arc-shaped blades with a single curvature direction, which causes the radial velocity of the impurities to be low at the inlet, the speed difference between the fan blades and the impurities at the inlet to be too large, the impurities to impact more when flowing along the surface of the blades, and the impurities to be easily entangled. The space in the high-pressure area close to the fan shell of the flat or forwardly convex blades is small. After the area is occupied by the impurities, the remaining space is small, and it is difficult to leave enough space to accommodate the compressed air under the centrifugal action, so it is difficult to ensure the static pressure at the outlet of the fan, and the fan is easily blocked when there are many impurities. Widening the fan blades can effectively improve the theoretical flow of the fan, but since the material moves along the axial direction and also moves along the radial direction, the axial movement speed of the impurities in the centrifugal fan is often less than the radial movement speed, so the inner side of the fan blade far from the air inlet is difficult to contact the impurities, and the utilization rate of the blade is not high.

[0048] The impurity removal fan provided in the embodiment has the arc line of the blade generatrix 311 of the spiral fan blade 310 close to the transmission shaft 200 being forwardly convex, and the relative speed of the impurities and the blade in the radial movement process is backward and the absolute speed is forward, which reduces the speed difference between the impurities and the blade at the inlet, reduces the running impact, and makes the flow of the impurities more smooth.

[0049] Further, the arc line of the blade generatrix 311 of the spiral fan blade 310 away from the transmission shaft 200 is rearwardly concave, which reserves a larger end high-pressure area space, and there is still enough space to retain high-pressure air when there are many impurities, which ensures the ability of the fan to maintain the maximum static pressure, effectively avoids the problem that the fan is easily blocked when there are many impurities, improves the impurity removal efficiency, and reduces energy consumption.

[0050] In addition, the axial spiral of the spiral fan blade 310 can drive the impurities to move axially towards the inside of the spiral fan blade 310 during the radial movement, reducing the speed difference between the axial and radial movements of the material in the wide-blade fan, and effectively avoiding the problem of low utilization rate of the inside of the wide-blade spiral fan blade 310.

[0051] Furthermore, this embodiment also provides a waste removal system for a corn harvester, including the waste removal fan provided in Embodiment 1 above.

[0052] This embodiment also provides a corn harvester, including the aforementioned corn harvester debris removal system.

[0053] Example 2

[0054] Please see Figure 1 and Figure 2 This embodiment provides a waste removal fan, whose main function is to remove waste (such as corn leaves, stalks, husks, etc.) generated during corn harvesting, so as to reduce the workload of the peeling machine and improve harvesting efficiency and quality.

[0055] The exhaust fan provided in this embodiment includes: a fan housing 100, a drive shaft 200, and an impeller 300; the drive shaft 200 is rotatably mounted on the fan housing 100 and is used for drive connection with a motor; the impeller 300 is mounted on the drive shaft 200 and includes multiple spiral fan blades 310. The fan housing 100 is provided with a reserved air inlet 110 and a reserved air outlet 120.

[0056] Take the normal plane along the rotation axis of the spiral fan blade 310. From the direction of the normal plane, the direction of rotation of the spiral fan blade 310 is the positive direction, and the opposite direction is the negative direction. The intersection line of the normal plane and the spiral fan blade 310 is the blade generatrix 311.

[0057] In this embodiment, the shape of the blade generatrix 311 is a double-segment circular arc with a continuous slope. The double-segment circular arc includes a first circular arc segment 311a and a second circular arc segment 311b. The first circular arc segment 311a is close to the axis and has a positive curvature, while the second circular arc segment 311b is far from the axis and has a negative curvature.

[0058] Furthermore, the point with a curvature of 0 in the blade generatrix 311 is defined as N, and the length of the line segment from point N to the outer side of the spiral fan blade 310 along the radial direction on the outer surface of the transmission shaft 200 is defined as L.

[0059] The distance from point N to the outer surface of the drive shaft 200 is L1, and the distance from point N to the outer side of the spiral fan blade 310 is L2, where L1:L2 = 0.34~0.46. This ensures a larger high-pressure zone space on the outer side of the spiral blade, allowing it to accommodate more air and impurities, improving impurity removal efficiency, and preventing impurity blockage.

[0060] In some embodiments, L1:L2 can be selected in the range of 0.4-0.45.

[0061] Alternatively, L1:L2 can also be selected as 0.41, 0.415, 0.42, 0.427, 0.43, 0.431, 0.436, 0.442 or 0.44, etc. It should be understood that the above are only illustrative and not as a limitation on the scope of protection of the present application.

[0062] Please refer to Figure 3 Further, define the point with 0 curvature in the blade generatrix 311 as N, the length of the line segment from the outer surface of the transmission shaft 200 to the outside of the spiral fan blade 310 along the radial direction through the point N as L, and the width of the spiral fan blade 310 as H; wherein H:L = 1-1.35. It can be understood that too large depth of the impurity removal fan can result in waste of the width of the spiral fan blade 310 and insufficient utilization; too small depth can result in insufficient air volume, so that the width of the spiral fan blade 310 can be reasonably utilized within the range and sufficient air volume can be ensured.

[0063] In some embodiments, H:L can be selected in the range of 1-1.3.

[0064] Alternatively, H:L can also be selected as 0.11, 0.113, 0.118, 0.12, 0.123, 0.125, 0.127 or 0.129, etc. It should be understood that the above are only illustrative and not as a limitation on the scope of protection of the present application.

[0065] Please refer to Figure 1 and Figure 2 A plurality of virtual points are defined on the blade generatrix 311, the plurality of virtual points are respectively the point O at the intersection of the blade generatrix 311 and the outer circle of the transmission shaft 200, the point M at the outermost side of the blade generatrix 311, the point N with 0 curvature in the blade generatrix 311, and the point A in the blade generatrix 311.

[0066] Wherein, the angle between the tangent line of the blade generatrix 311 at the point A and the radial line of the point O passing through the point O is θ, when the point A coincides with the point O, θ is greater than 0 degrees, when the point A moves along the blade generatrix 311 from the point O to the point N, θ gradually increases, and when the point A moves along the blade generatrix 311 from the point N to the point M, θ gradually decreases.

[0067] Alternatively, the angle range of θ at the point O is 20°-32°. The angle range of θ at the point M is 0°-12°.

[0068] Please refer to Figure 3, the helical line of the spiral fan blade 310 rotating around the transmission shaft 200 is defined as a spiral guide line 312 of the spiral fan blade 310, and the spiral guide line 312 is divided into two (i.e., an inner spiral guide line 312a and an outer spiral guide line 312b). The blade generatrix 311 moves along the spiral guide line 312 to form the curved surface of the spiral fan blade 310. Any two points (point O and point M) on the blade generatrix 311 move along the inner and outer spiral guide lines 312 with the same pitch, the same rotation direction, and different rotation diameters during the movement of the tangent plane along the transmission shaft 200 in one direction, and guide the generatrix to form the blade curved surface. In the direction perpendicular to the air inlet outward (i.e., the opposite direction of the direction of the remaining materials), the spiral direction of the spiral guide line 312 is left-handed. In order to further improve the pushing effect of the spiral fan blade 310 on the remaining materials, the ratio of the pitch of the spiral guide line 312 to the width of the spiral fan blade 310 and the radius of revolution of the spiral fan blade 310 is inversely proportional (the wider the blade of the spiral fan blade 310, the smaller the pitch of the fan guide line).

[0069] Optionally, the slope of the inner spiral guide line 312a relative to the transmission shaft 200 is 0.1-0.2. The slope of the outer spiral guide line 312b relative to the transmission shaft 200 is 0.4-0.6.

[0070] In some embodiments, the curvature radius of the first circular arc line segment 311a is R1, the curvature radius of the second circular arc line segment 311b is R2, and R1:R2=1:1.15.

[0071] Compared with the prior art, the impurity removal fan provided in the embodiment has the following advantages. Since the curvature of the arc line segment of the blade generatrix 311 close to the shaft center is positive, the arc line of the blade generatrix 311 close to the transmission shaft 200 of the spiral fan blade 310 is convex forward. During the radial movement of the remaining materials, there is a relative speed backward and an absolute speed forward between the remaining materials and the blade, which reduces the speed difference between the remaining materials and the blade at the inlet, reduces the running impact, and makes the flow of the remaining materials more smooth.

[0072] Further, since the curvature of the arc line segment far from the shaft center is negative, the arc line of the blade generatrix 311 far from the transmission shaft 200 of the spiral fan blade 310 is concave backward, which retains a larger high-pressure area space. In the case of more remaining materials, there is still enough space to retain high-pressure air, which ensures the ability of the fan to maintain the maximum static pressure, effectively avoids the problem that the fan is easily blocked when there are more remaining materials, improves the impurity removal efficiency, and reduces the energy consumption.

[0073] In addition, the axial spiral of the spiral fan blade 310 can push the remaining materials to move axially inward during the radial movement, which reduces the speed difference between the axial movement and the radial movement of the wide-blade fan materials, and effectively avoids the problem of low utilization rate of the inner side of the wide-blade spiral fan blade 310.

[0074] Further, the embodiment also provides a corn harvester impurity removal system, which comprises the impurity removal fan provided in the above embodiment two.

[0075] The embodiment also provides a corn harvester, which comprises the corn harvester impurity removal system provided in the above.

[0076] It should be noted that, in the present application, the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0077] In the description of the present application, it should be understood that the terms "first", "second" are only used for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0078] In the present application, unless otherwise specifically defined and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected or in communication with each other; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication or interaction relationship of two elements, unless otherwise specifically limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0079] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0080] Although the embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and are not to be construed as limiting the present application, and the person skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A dust removal fan for a corn harvester, characterized in that, include: Fan casing (100); A drive shaft (200) is rotatably mounted on the fan housing (100); and An impeller (300) is disposed on the drive shaft (200), and the impeller (300) includes a plurality of spiral fan blades (310). Wherein, along the rotation axis of the spiral fan blade (310), take the normal plane. From the direction of the normal plane, take the rotation direction of the spiral fan blade (310) as the positive direction and the opposite direction as the negative direction. The intersection line of the normal plane and the spiral fan blade (310) is the blade generatrix (311). The shape of the blade generatrix (311) is a multi-segment arc with a continuous slope. The curvature of the arc segment near the axis of the transmission shaft (200) is positive, and the curvature of the arc segment away from the axis of the transmission shaft (200) is negative.

2. The dust removal fan for a corn harvester according to claim 1, characterized in that, The shape of the blade generatrix (311) is a multi-segment circular arc with a continuous slope; The curvature of the arc segment near the center of the drive shaft (200) is positive, while the curvature of the arc segment away from the center of the drive shaft (200) is negative.

3. The dust removal fan for a corn harvester according to claim 1, characterized in that, The shape of the blade generatrix (311) is a double-segment circular arc with a continuous slope, the double-segment circular arc including a first circular arc segment (311a) and a second circular arc segment (311b). The first arc segment (311a) is close to the axis of the drive shaft (200) and has a positive curvature, while the second arc segment (311b) is far from the axis of the drive shaft (200) and has a negative curvature.

4. The dust removal fan for a corn harvester according to claim 3, characterized in that, Define N as the point with 0 curvature in the blade generatrix (311), and define L as the length of the line segment from point N to the outer side of the spiral fan blade (310) along the radial direction on the outer surface of the transmission shaft (200); Wherein, the distance from point N to the outer surface of the transmission shaft (200) is L1, and the distance from point N to the outer side of the spiral fan blade (310) is L2, L1:L2=0.34~0.

46.

5. The dust removal fan for a corn harvester according to claim 3, characterized in that, Define N as the point with 0 curvature in the blade generatrix (311), L as the length of the line segment from point N to the outside of the spiral fan blade (310) along the radial direction on the outer surface of the transmission shaft (200), and H as the width of the spiral fan blade (310). Where H:L = 1~1.

35.

6. The dust removal fan for a corn harvester according to claim 3, characterized in that, The point at the intersection of the outer circle of the blade generatrix (311) and the transmission shaft (200) is defined as O, the outermost point of the blade generatrix (311) is defined as M, the point with curvature of 0 in the blade generatrix (311) is defined as N, and the blade generatrix (311) is also provided with point A. The angle between the tangent of the blade generatrix (311) at point A and the radial line of the axis of the transmission shaft (200) passing through point O is θ. When point A coincides with point O, θ is greater than 0 degrees. When point A moves from point O to point N along the blade generatrix (311), θ gradually increases. When point A moves from point N to point M along the blade generatrix (311), θ gradually decreases.

7. The dust removal fan for a corn harvester according to claim 1, characterized in that, The spiral line of the spiral fan blade (310) rotating around the transmission shaft (200) is defined as the spiral guide wire (312) of the spiral fan blade (310). The pitch of the spiral guide wire (312) is inversely proportional to the ratio of the width of the spiral fan blade (310) to the radius of rotation of the spiral fan blade (310).

8. The dust removal fan for a corn harvester according to any one of claims 1-7, characterized in that, The fan casing (100) is provided with a reserved air inlet (110) and a reserved air outlet (120).

9. A waste removal system for a corn harvester, characterized in that, Includes a dust removal fan for a corn harvester according to any one of claims 1-8.

10. A corn harvester, characterized in that, Includes the waste removal system for a corn harvester as described in claim 9.

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