A low-resistance powder concentrator rotor structure

Abstract

A low-resistance powder concentrator rotor structure, a rotor upper cover plate, a rotor middle plate and a rotor lower cover plate are arranged from top to bottom on the outside of a rotor shaft sleeve and a rotor cone, the rotor upper cover plate and the rotor middle plate are connected with the rotor shaft sleeve or the rotor cone through a rotor connecting plate, and the rotor lower cover plate is directly connected with the rotor cone; a plurality of inclined grooves are formed on the rotor upper cover plate and the rotor middle plate; the rotor connecting plates are arranged in pairs, have the same shape and are symmetrical about the rotor axis; the shapes of the adjacent two rotor connecting plates are different, the included angles with the horizontal plane are different, and the rotor connecting plates are arranged in the form of vertical plates, so that the high-speed airflow in the rotor cage is hindered and scattered. The present application interferes with the generation of the resistance surface of the connecting part position by the special connecting plate and vertical rod arrangement, so that the number of the connecting parts in the same plane or cone surface is small, the ventilation cross-sectional area is increased, and the power consumption of the vertical mill system fan is reduced.

Description

Technical Field

[0001] This invention relates to the field of vertical mill classifiers, specifically to a low-resistance rotor structure for a vertical mill classifier, which can reduce the resistance of powder passing through the rotor, thereby reducing ventilation power consumption, saving energy in production, and improving the economic efficiency of the mill. Background Technology

[0002] A vertical mill classifier is a separation device located above a vertical mill. Its function is to separate the finished fine powder of the required fineness, discharging it through the outlet into the mill cavity. Coarse powder that does not meet the fineness requirement cannot pass through the classifier's separation mechanism and returns to the vertical mill's grinding mechanism for further grinding. Currently, the basic classification principle of various vertical mill classifiers is consistent; they are all designed based on the planar vortex classification mechanism. A common structural feature is a cage-shaped classifying rotor at the center of the classifier. The material being ground is carried away by the system's airflow, forming a high-concentration dust-laden gas that reaches the cage-shaped classifying rotor. The rotating cage-shaped rotor creates a forced vortex classification flow field. Qualified fine powder enters the rotor through the gaps between the blades and is then discharged through the outlet, while unqualified coarse powder falls into the vertical mill's grinding area for further grinding.

[0003] With the continuous development and progress of society, traditional manufacturing enterprises face higher standards and requirements. For any equipment, energy efficiency is increasingly becoming a key indicator for users. Lower unit power consumption in vertical mill classifiers signifies superior performance and reflects more advanced technology. To improve the production efficiency and reduce power consumption of vertical mill classifiers, improvements were made to the cage rotor, resulting in the invention of a low-resistance classifier rotor structure.

[0004] Currently, most air classifier rotor structures consist of: a central bushing or rotor cone; rotor blades evenly distributed along the outer edge; and cover plates that fix the rotor blades along the height. These cover plates are secured by circumferentially distributed uprights. Small-diameter rotor cover plates are typically one-piece, with circumferentially distributed spokes of a certain width connecting to the rotor bushing or conical rotor body. Large-diameter rotor cover plates are connected to the rotor bushing or rotor cone by connecting plates or steel pipes. These common rotor structures currently suffer from the following problems:

[0005] (1) An integrated rotor cover or a flat rotor connecting plate is adopted. In order to ensure structural strength and rigidity, the rotor cover and rotor connecting plate have a certain width. This structure results in a small rotor outlet cross-sectional area, which leads to high rotor ventilation resistance, resulting in high ventilation power consumption of the vertical mill system and the inability to effectively reflect the economy of the vertical mill system.

[0006] (2) The rotor connecting plates or rotor connecting steel pipes are distributed on the same plane or conical surface. Currently, all the connecting plates or other types of connecting parts of the classifier rotor are horizontally distributed on the same surface, or obliquely connected to the rotor cone and distributed on the same conical surface. This will result in a large number of rotating components on the same plane, forming a resistance surface near the rotating plane, resulting in high rotor ventilation resistance.

[0007] (3) The rotor wears out quickly. Due to the use of an integrated rotor cover or a flat connecting plate, the dust-laden gas will maintain a high speed and rotate around the rotor shaft to form a vortex after entering the rotor. The fluid resistance is high and the speed of the powder is very high, which will accelerate the wear of the rotor structure. Summary of the Invention

[0008] The technical problem to be solved by this invention is: how to reduce the resistance of powder passing through the rotating drum and reduce the power consumption of the vertical mill system. Therefore, a low-resistance classifier rotor structure is provided.

[0009] The specific technical solution of the present invention is as follows:

[0010] A rotor structure for a low-resistance air classifier includes a rotor bushing and a rotor cone fixed outside the rotor bushing. From top to bottom, an upper rotor cover plate, a middle rotor plate, and a lower rotor cover plate are respectively arranged on the outer sides of the rotor bushing and the rotor cone. The upper rotor cover plate and the middle rotor plate are connected to the rotor bushing or the rotor cone via rotor connecting plates, and the lower rotor cover plate is directly connected to the rotor cone. Several inclined slots are formed on the upper rotor cover plate and the middle rotor plate, and rotor blades are arranged in each inclined slot.

[0011] Furthermore, rotor uprights are provided on the inner side of the rotor top cover plate and the rotor intermediate plate, and the rotor uprights are distributed on the outer side of the rotor bushing with unequal diameters along the circumference.

[0012] The rotor connecting plates are arranged in pairs, with the same shape and symmetrical about the rotor axis; adjacent rotor connecting plates have different shapes and different angles with the horizontal plane, and the rotor connecting plates are arranged in a vertical manner. In the height direction, the rotor connecting plates arranged at different angles obstruct and disperse the high-speed airflow inside the rotor cage.

[0013] Both the rotor top cover plate and the rotor intermediate plate are circular ring plates, and the inclined slots are evenly arranged on the outermost side of the circular ring plates along the circumference.

[0014] Both the upper cover plate and the middle plate of the rotor have protruding parts of unequal lengths on their inner sides. The protruding parts are evenly distributed along the circumference. Adjacent protruding parts have different lengths, while protruding parts at relative positions have the same length. Through holes are opened on the protruding parts, and the distance of the through holes relative to the center varies depending on the length of the protruding parts. The rotor upright passes through the through holes of the protruding parts on the upper cover plate and the middle plate of the rotor, and the lower part of the rotor upright is fixed to the lower cover plate of the rotor.

[0015] The rotor top cover and rotor intermediate plate have eight protruding parts of unequal length on the inner side of the plate, which are divided into four groups. Two protruding parts facing each other form a group. They are symmetrical with respect to the center. The lengths of adjacent protruding parts are not equal. The protrusion distance of the protruding parts is determined by the fixed rotor uprights. The radius r of each group of rotor uprights relative to the rotor axis is different, and r1>r2>r3>r4. The distance of each group of uprights from the rotor axis increases, with an increment of a.

[0016] The rotor connecting plate includes a rotor connecting upper plate and a rotor connecting middle plate. The rotor connecting upper plate includes a first rotor connecting upper plate, a second rotor connecting upper plate, a third rotor connecting upper plate, and a fourth connecting upper plate arranged sequentially adjacent to each other. The first rotor connecting upper plate is connected to a rotor bushing at one end and to a protruding part at the other end. The second, third, and fourth rotor connecting upper plates are connected to a rotor cone at one end and to different protruding parts on the rotor upper cover plate at the other end. The rotor connecting middle plate includes a first rotor connecting middle plate, a second rotor connecting middle plate, a third rotor connecting middle plate, and a fourth connecting middle plate arranged sequentially adjacent to each other. The rotor connecting middle plate is connected to different protruding parts on the rotor middle plate at one end and to the rotor cone at the other end.

[0017] The first rotor connecting upper plate has an angle α1=0° with the horizontal plane, one end is connected to the fixed rotor upper cover plate, and the other end is connected to the fixed rotor shaft sleeve. The first rotor connecting middle plate has an angle 0°≤α2≤15° with the horizontal plane, one end is connected to the fixed rotor middle plate, and the other end is connected to the fixed rotor cone.

[0018] The second rotor connecting plate has an angle of 15°≤α3≤30° with the horizontal plane, one end of which is connected to the fixed rotor upper cover plate and the other end of which is connected to the fixed rotor cone; the second rotor connecting middle plate has an angle of α4=0° with the horizontal plane, one end of which is connected to the fixed rotor middle plate and the other end of which is connected to the fixed rotor cone.

[0019] The angle between the upper plate of the third rotor and the horizontal plane is 30°≤α5≤45°, one end is connected to the upper cover plate of the fixed rotor, and the other end is connected to the cone of the fixed rotor; the angle between the middle plate of the third rotor and the horizontal plane is 15°≤α6≤30°, one end is connected to the middle plate of the fixed rotor, and the other end is connected to the cone of the fixed rotor.

[0020] The fourth connecting plate has an angle of 45°≤α7≤60° with the horizontal plane, one end of which is connected to the fixed rotor upper cover plate and the other end of which is connected to the fixed rotor cone; the fourth connecting middle plate has an angle of 30°≤α8≤45° with the horizontal plane, one end of which is connected to the fixed rotor middle plate and the other end of which is connected to the fixed rotor cone.

[0021] The beneficial effects of this invention are as follows:

[0022] (1) Reduce power consumption of vertical mill system. By using special connecting plates and uprights, the generation of resistance surface at the connecting parts is interfered with. At the same time, the special arrangement of connecting parts reduces the number of connecting parts on the same plane or conical surface, increasing the ventilation cross-sectional area. The vertically placed connecting plates also increase the ventilation cross-sectional area, effectively reducing the ventilation resistance inside the rotor and reducing the pressure loss at the rotor. This helps to reduce the power consumption of the vertical mill system fan and improve the economy of the vertical mill system.

[0023] (2) Reduce power consumption and rotor wear in vertical mill classifiers. By fixing the vertical mill and using connecting plates that are distributed at different angles to the horizontal plane, the formation of eddies inside the rotor cage can be effectively interfered with. As the eddy phenomenon is weakened, the dust-laden gas will pass through the inside of the rotor in a shorter distance, reducing rotor structural wear caused by eddies. At the same time, the special connecting plate arrangement structure, by eliminating the thrust of eddies, is equivalent to applying a driving force to the rotor, reducing the power consumption of the classifier.

[0024] (3) Improved working efficiency of the air classifier. Because this structure reduces the ventilation resistance of the rotor and effectively reduces the eddy current intensity inside the rotor, the pressure drop of dust-laden gas passing through the rotor is smaller, the resistance is smaller, and the distance required to pass through the rotor is shorter, which is conducive to the rapid passage of qualified powder through the rotor and avoids the qualified powder from continuing to circulate in the mill. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the rotor structure;

[0026] Figure 2 A schematic diagram of a rotor structure with rotor blades added;

[0027] Figure 3 This is a top view of the rotor structure;

[0028] Figure 4 This is a schematic diagram of the cross-section at orientation A;

[0029] Figure 5 This is a schematic diagram of the cross-section at orientation B;

[0030] Figure 6 This is a schematic diagram of the cross-section at orientation C;

[0031] Figure 7 This is a schematic diagram of the cross-section at orientation D. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0034] like Figure 1 , Figure 2 As shown, a low-resistance air classifier rotor structure includes a rotor sleeve 1 and a rotor cone 2 fixed outside the rotor sleeve 1. From top to bottom, an upper rotor cover plate 3, a middle rotor plate 6, and a lower rotor cover plate 7 are respectively arranged on the outer sides of the rotor sleeve 1 and the rotor cone 2. The upper rotor cover plate 3 and the middle rotor plate 6 are connected to the rotor sleeve 1 or the rotor cone 2 respectively via rotor connecting plates. The lower rotor cover plate 7 is directly connected to the rotor cone 2. Several inclined slots 5 are formed on the upper rotor cover plate 3 and the middle rotor plate 6, and rotor blades 16 are arranged in each inclined slot 5.

[0035] Both the rotor cover plate 3 and the rotor intermediate plate 6 are annular plates, and the inclined grooves 5 are evenly arranged on the outermost side of the annular plates along the circumference.

[0036] Furthermore, rotor uprights 4 are provided on the inner sides of the rotor upper cover plate 3 and the rotor intermediate plate 6, and the rotor uprights 4 are distributed unequally in diameter along the circumferential direction on the outer side of the rotor bushing 1. Further, protruding portions 17 of unequal lengths are provided on the inner sides of both the rotor upper cover plate 3 and the rotor intermediate plate 6. The protruding portions 17 are evenly distributed along the circumferential direction, with adjacent protruding portions 17 having different lengths, while protruding portions 17 in relatively opposite positions have the same length. Through holes are opened on the protruding portions 17, and the distance of the through holes relative to the center varies depending on the length of the protruding portion. The rotor uprights 4 pass through the through holes of the protruding portions 17 on the rotor upper cover plate 3 and the rotor intermediate plate 6. The lower part of the rotor uprights 4 is fixed to the rotor lower cover plate 7. According to the arrangement of the through holes on the rotor upper cover plate 3 and the rotor intermediate plate 6, the rotor uprights 4 are distributed unequally in the circumferential direction about the axis.

[0037] Furthermore, the rotor upper cover plate 3 and the rotor intermediate plate 6 have eight protruding portions 17 of unequal lengths on their inner sides, divided into four groups of two opposing protruding portions 17, symmetrical about the center, with adjacent protruding portions having unequal lengths. The protrusion distance of the protruding portions 17 is determined by the fixed rotor upright 4. Figure 3 As shown, there are 8 rotor uprights 4 evenly distributed along the circumference of the rotor, with two uprights in opposite directions forming a group. The 8 rotor uprights 4 are divided into four groups. The radius r of each group of rotor uprights 4 relative to the rotor axis is different, ensuring that r1>r2>r3>r4. The distance of each group of uprights from the rotor axis increases by an increment of a, i.e., r3=r4+a, r2=r3+a, r1=r2+a. This structure reduces the number of rotor uprights 4 located in the same cylindrical surface, distributing them with different radii in different cylindrical surfaces. At the same time, the two rotor uprights 4 in the same group are symmetrically distributed, ensuring that the rotor's center of mass is located on the rotor axis, thus ensuring the dynamic balance of the rotor rotation.

[0038] Meanwhile, one end of the rotor connecting plate is connected to the rotor upper cover plate 3 and the extended portion 17 of the rotor intermediate plate 6, and the other end is connected to the rotor bushing 1 or the rotor cone 2. The rotor connecting plates are arranged in pairs, with identical shapes and symmetrical about the rotor axis. Adjacent rotor connecting plates have different shapes and different angles with the horizontal plane. Furthermore, the rotor connecting plates are arranged vertically. The different angles of the rotor connecting plates in the height direction prevent the interior of the rotor cage from becoming an unobstructed space, effectively hindering and dispersing high-speed airflow, and ensuring good dynamic balance during rotor rotation.

[0039] The rotor connecting plate includes a rotor connecting upper plate and a rotor connecting middle plate. The rotor connecting upper plate includes a first rotor connecting upper plate 8, a second rotor connecting upper plate 10, a third rotor connecting upper plate 12, and a fourth connecting upper plate 14 arranged sequentially adjacent to each other. The first rotor connecting upper plate 8 is connected to the rotor bushing 1 at one end and to the protruding part 17 at the other end. The second rotor connecting upper plate 10, the third rotor connecting upper plate 12, and the fourth connecting upper plate 14 are connected to the rotor cone 2 at one end and to different protruding parts 17 on the rotor upper cover plate 3 at the other end.

[0040] The rotor connecting plate includes a first rotor connecting plate 9, a second rotor connecting plate 11, a third rotor connecting plate 13, and a fourth connecting plate 15 arranged sequentially adjacent to each other; wherein, one end of the rotor connecting plate is connected to different protruding parts 17 on the rotor intermediate plate 6, and the other end is connected to the rotor cone 2.

[0041] like Figure 4 , Figure 5 , Figure 6 , Figure 7As shown, this is a cross-sectional view of the rotor along four different orientations (ABCD). The rotor uprights 4 and rotor connecting plates located on the same cross-section are symmetrically distributed about the rotor center, and each group of rotor connecting plates has a different angle with the horizontal plane.

[0042] Figure 4 In the middle section, the first rotor connecting plate 8 has an angle α1=0° with the horizontal plane, one end of which is connected to the fixed rotor upper cover plate 3, and the other end is connected to the fixed rotor shaft sleeve 1. The first rotor connecting middle plate 9 has an angle 0°≤α2≤15° with the horizontal plane, one end of which is connected to the fixed rotor middle plate 6, and the other end is connected to the fixed rotor cone 2.

[0043] Figure 5 In the middle section, the second rotor connecting plate 10 has an angle of 15°≤α3≤30° with the horizontal plane, one end of which is connected to the fixed rotor upper cover plate 3, and the other end is connected to the fixed rotor cone 2; the second rotor connecting middle plate 11 has an angle of α4=0° with the horizontal plane, one end of which is connected to the fixed rotor middle plate 6, and the other end is connected to the fixed rotor cone 2.

[0044] Figure 6 In the middle section, the third rotor connecting plate 12 has an angle of 30°≤α5≤45° with the horizontal plane, one end of which is connected to the fixed rotor upper cover plate 3, and the other end is connected to the fixed rotor cone 2; the third rotor connecting middle plate 13 has an angle of 15°≤α6≤30° with the horizontal plane, one end of which is connected to the fixed rotor middle plate 6, and the other end is connected to the fixed rotor cone 2.

[0045] Figure 7 In the middle section, the fourth connecting upper plate 14 has an angle of 45°≤α7≤60° with the horizontal plane, one end of which is connected to the fixed rotor upper cover plate 3, and the other end is connected to the fixed rotor cone 2; the fourth connecting middle plate 15 has an angle of 30°≤α8≤45° with the horizontal plane, one end of which is connected to the fixed rotor middle plate 6, and the other end is connected to the fixed rotor cone 2.

[0046] All of the rotor connecting plates mentioned above are arranged with vertical ribs, which further enhances the rigidity of the rotor.

[0047] The working principle of this invention is:

[0048] The connecting plates are designed with vertical ribs, and each set of connecting plates has a different angle with the horizontal plane. The distribution of connecting plates with different angles reduces the number of connecting plates in the same plane or conical surface, thereby reducing the resistance of that plane and facilitating the passage of powder. At the same time, the vertically placed connecting plates can weaken the intensity of the vortex inside the rotor cage, reduce the circumferential airflow velocity, and slow down the wear rate of the rotor structure. The rotor uprights are distributed with unequal diameters relative to the rotor shaft center. Compared with rotor uprights with equal diameters, the unequal diameter structure reduces the number of uprights on the same cylindrical surface, which can effectively reduce the resistance of the upright cylindrical surface. This low-resistance classifier rotor structure can reduce the resistance of powder passing through the rotating cage, reduce the power consumption of the vertical mill system, and improve economic efficiency.

[0049] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several changes and improvements without departing from the overall concept of the present invention, and these should also be considered within the scope of protection of the present invention.

Claims

1. A low-resistance classifier rotor structure, characterized by: The system includes a rotor bushing (1) and a rotor cone (2) fixed outside the rotor bushing (1). From top to bottom, a rotor upper cover plate (3), a rotor intermediate plate (6), and a rotor lower cover plate (7) are respectively provided on the outer side of the rotor bushing (1) and the rotor cone (2). The rotor upper cover plate (3) and the rotor intermediate plate (6) are respectively connected to the rotor bushing (1) or the rotor cone (2) through a rotor connecting plate. The rotor lower cover plate (7) is directly connected to the rotor cone (2). Several inclined slots (5) are opened on the rotor upper cover plate (3) and the rotor intermediate plate (6). Each inclined slot (5) is provided with a rotor blade (16). Furthermore, rotor uprights (4) are provided on the inner side of the rotor upper cover plate (3) and the rotor intermediate plate (6), and the rotor uprights (4) are distributed on the outer side of the rotor bushing (1) with unequal diameters along the circumferential direction; Both the upper cover plate (3) and the middle plate (6) of the rotor are provided with protruding parts (17) of unequal length. The protruding parts (17) are evenly distributed along the circumferential direction. The lengths of adjacent protruding parts (17) are different, while the lengths of protruding parts (17) at relative positions are the same. Through holes are opened on the protruding parts (17). The distance of the through holes relative to the center is different depending on the length of the protruding parts. The rotor upright (4) passes through the through holes of the protruding parts (17) on the upper cover plate (3) and the middle plate (6) of the rotor. The lower part of the rotor upright (4) is fixed to the lower cover plate (7) of the rotor. The rotor connecting plates are arranged in pairs, with the same shape and symmetrical about the rotor axis; adjacent rotor connecting plates have different shapes and different angles with the horizontal plane, and the rotor connecting plates are arranged in a vertical manner. In the height direction, the rotor connecting plates arranged at different angles obstruct and disperse the high-speed airflow inside the rotor cage.

2. The rotor structure of a low-resistance air classifier according to claim 1, characterized in that: Both the rotor top cover plate (3) and the rotor intermediate plate (6) are circular ring plates, and the inclined grooves (5) are evenly arranged on the outermost side of the circular ring plates along the circumference.

3. The rotor structure of a low-resistance air classifier according to claim 1, characterized in that: The rotor cover plate (3) and the rotor intermediate plate (6) have eight protruding parts (17) of unequal length on the inner side of the plate, which are divided into four groups. Two protruding parts (17) facing each other form a group. They are symmetrical with respect to the center. The lengths of adjacent protruding parts are not equal. The protrusion distance of the protruding parts (17) is determined by the fixed rotor uprights (4). The radius r of each group of rotor uprights (4) relative to the rotor axis is different, and r1> r2> r3> r4. The distance of each group of uprights from the rotor axis increases, with an increment of a.

4. The rotor structure of a low-resistance air classifier according to claim 1, characterized in that: The rotor connecting plate includes a rotor connecting upper plate and a rotor connecting middle plate. The rotor connecting upper plate includes a first rotor connecting upper plate (8), a second rotor connecting upper plate (10), a third rotor connecting upper plate (12), and a fourth connecting upper plate (14) arranged sequentially and adjacently. The first rotor connecting upper plate (8) is connected to the rotor bushing (1) at one end and to the protruding part (17) at the other end. The second rotor connecting upper plate (10), the third rotor connecting upper plate (12), and the fourth connecting upper plate (14) are connected to the rotor cone (2) at one end and to different protruding parts (17) on the rotor upper cover plate (3) at the other end. The rotor connecting middle plate includes a first rotor connecting middle plate (9), a second rotor connecting middle plate (11), a third rotor connecting middle plate (13), and a fourth connecting middle plate (15) arranged sequentially and adjacently. The rotor connecting middle plate is connected to different protruding parts (17) on the rotor middle plate (6) at one end and to the rotor cone (2) at the other end.

5. The rotor structure of a low-resistance air classifier according to claim 4, characterized in that: The first rotor connecting plate (8) has an angle α1=0° with the horizontal plane, one end of which is connected to the fixed rotor upper cover plate (3), and the other end is connected to the fixed rotor bushing (1). The first rotor connecting middle plate (9) has an angle 0°≤α2≤15° with the horizontal plane, one end of which is connected to the fixed rotor middle plate (6), and the other end is connected to the fixed rotor cone (2). The second rotor connecting plate (10) has an angle of 15°≤α3≤30° with the horizontal plane, one end of which is connected to the fixed rotor upper cover plate (3), and the other end is connected to the fixed rotor cone (2); the second rotor connecting middle plate (11) has an angle of α4=0° with the horizontal plane, one end of which is connected to the fixed rotor middle plate (6), and the other end is connected to the fixed rotor cone (2). The third rotor connecting plate (12) has an angle of 30°≤α5≤45° with the horizontal plane, one end of which is connected to the fixed rotor upper cover plate (3), and the other end is connected to the fixed rotor cone (2); the third rotor connecting middle plate (13) has an angle of 15°≤α6≤30° with the horizontal plane, one end of which is connected to the fixed rotor middle plate (6), and the other end is connected to the fixed rotor cone (2). The fourth connecting plate (14) has an angle of 45°≤α7≤60° with the horizontal plane, one end of which is connected to the fixed rotor upper cover plate (3), and the other end is connected to the fixed rotor cone (2); the fourth connecting middle plate (15) has an angle of 30°≤α8≤45° with the horizontal plane, one end of which is connected to the fixed rotor middle plate (6), and the other end is connected to the fixed rotor cone (2).

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