Centrifugal fan volute for testing

Abstract

The centrifugal fan volute for testing comprises a front cover plate, a rear cover plate, an annular wall and multiple adjusting mechanisms, the annular wall is located between the front cover plate and the rear cover plate, each adjusting mechanism comprises a rotating shaft, an adjusting rod, a first limiting plate and a second limiting plate, the first limiting plate and the second limiting plate are connected to the two ends of the adjusting rod correspondingly, and the first limiting plate is located on the side, away from the rear cover plate, of the front cover plate; the second limiting plate is located on the side, away from the front cover plate, of the rear cover plate, and at least one end of the adjusting rod is a threaded end which is in threaded connection with the first limiting plate or the second limiting plate. The number of the rotating shafts is two, the first limiting plate is rotatably connected to the front cover plate around one rotating shaft, the second limiting plate is rotatably connected to the rear cover plate around the other rotating shaft, and the rotating shaft arranged corresponding to the threaded end is detachably connected with the front cover plate or the rear cover plate. According to the centrifugal fan volute for testing, the problem that mechanical interference exists in the screwing process of the limiting plate relative to the threaded end is solved.

Description

Technical Field

[0001] The present application relates to the technical field of fans, and in particular to a centrifugal fan volute for testing. Background Art

[0002] During the testing process of traditional centrifugal fans, the design and manufacture of the volute structure faces a significant challenge. Whenever the test data reveals design deficiencies and a new design solution needs to be tried, a new volute needs to be processed, which leads to a long waiting time for proofing and significantly increases the length of the test cycle. This not only affects the time to market of the product, but also significantly increases the development cost. Therefore, it is necessary to design a centrifugal fan volute with adjustable profile for testing to avoid the need to process a new volute multiple times during the test process.

[0003] A common centrifugal fan volute for testing includes a front cover plate, a rear cover plate, an annular wall, and multiple adjustment mechanisms. The annular wall is located between the front cover plate and the rear cover plate. The multiple adjustment mechanisms are distributed along the circumference of the annular wall to adjust the contour of the annular wall. Specifically, each adjustment mechanism includes an adjustment rod and two limit plates respectively connected to both ends of the adjustment rod. The front cover plate and the rear cover plate are respectively provided with convex bulges, and the two limit plates are respectively rotatably connected to the convex bulges, and the adjustment rod is stopped on the outer side of the annular wall. As the limit plates rotate around the convex bulge to different positions, the position of the adjustment rod is adjusted, thereby achieving the contour adjustment of the annular wall.

[0004] In order to make the front cover plate and the rear cover plate tightly fixed to the annular wall, the two limit plates are respectively located on the two sides of the front cover plate and the rear cover plate that are away from each other, and the adjustment rod is provided with a threaded end, which is used to be threadedly connected with the limit plate. By screwing the limit plate connected to the threaded end, the limit plate moves along the axial direction of the adjustment rod, thereby adjusting the spacing between the two limit plates, and then realizing the tight connection between the front cover plate, the rear cover plate and the annular wall through the two limit plates. However, due to the existence of the convex bulge, the convex bulge easily hinders the limit plate from rotating around the threaded end, that is, there is mechanical interference in the process of screwing the limit plate relative to the threaded end, resulting in the limit plate being unable to press the front cover plate and the rear cover plate. Utility Model Content

[0005] Based on this, it is necessary to provide a centrifugal fan volute for testing that can avoid mechanical interference during the process of screwing the limit plate relative to the threaded end.

[0006] A centrifugal fan volute for testing, the centrifugal fan for testing comprises a front cover plate, a rear cover plate, an annular wall and a plurality of adjustment mechanisms, the annular wall is located between the front cover plate and the rear cover plate, the plurality of adjustment mechanisms are spaced along the circumference of the annular wall, and are used to connect the annular wall to the front cover plate and the rear cover plate and to adjust the profile of the annular wall. Each adjustment mechanism comprises a rotating shaft, an adjusting rod, and a first limiting plate and a second limiting plate respectively connected to both ends of the adjusting rod, the first limiting plate is located on the side of the front cover plate away from the rear cover plate, the second limiting plate is located on the side of the rear cover plate away from the front cover plate, at least one end of the adjusting rod is configured as a threaded end, and the threaded end is threadedly connected to the first limiting plate or the second limiting plate. The number of rotating shafts is configured as two, the first limiting plate is rotatably connected to the front cover plate around one of the rotating shafts, the second limiting plate is rotatably connected to the rear cover plate around the other rotating shaft, and the rotating shaft corresponding to the threaded end is configured to be detachably connected to the front cover plate or the rear cover plate.

[0007] In one embodiment, the rotating shaft is magnetically connected to the front cover plate or the rear cover plate.

[0008] In one embodiment, the rotating shaft includes a connecting block and a magnet, one end of the magnet is connected to the connecting block, and the other end is used to adsorb the front cover plate or the rear cover plate.

[0009] In one embodiment, the connection block has a positioning protrusion, the magnet is provided with a through hole, the front cover plate or the rear cover plate is provided with a positioning hole, and the positioning protrusion is used to penetrate the through hole and be inserted into the positioning hole.

[0010] In one embodiment, the cross-sectional shape of the positioning protrusion matches the shape of the positioning hole and is used to limit the connection block from rotating relative to the front cover plate or the rear cover plate.

[0011] In one embodiment, the cross section of the positioning protrusion is in the shape of an elongated strip, and the positioning hole is configured as a racetrack-shaped hole corresponding to the positioning protrusion.

[0012] In one embodiment, the test centrifugal fan volute further includes a sealing gasket, which is sandwiched between the front cover plate and the annular wall, and sandwiched between the rear cover plate and the annular wall. The sealing gasket is provided with an avoidance groove, which is connected to the positioning hole and is used to avoid the positioning protrusion.

[0013] In one embodiment, the rotating shaft is relatively stationary with the front cover plate or the rear cover plate, and the rotating shaft surface is provided with scale lines, and the first limit plate and the second limit plate are provided with marking parts corresponding to the scale lines. The marking parts are used to cooperate with the scale lines to record the angle of rotation of the first limit plate relative to the front cover plate around the rotating shaft, or the marking parts are used to cooperate with the scale lines to record the angle of rotation of the second limit plate relative to the rear cover plate around the rotating shaft.

[0014] In one embodiment, the rotating shaft further comprises a plastic scale sheet, the plastic scale sheet is fixedly connected to the connecting block, and the scale lines are arranged on the plastic scale sheet.

[0015] In one of the embodiments, one of the plastic scale sheet and the connecting block is provided with a positioning groove, and the other is provided with a positioning block, and the positioning block is used to engage with the positioning groove.

[0016] Compared with the prior art, the adjustment process of the adjustment mechanism of the test centrifugal fan volute provided by the present application can be as follows: first, the first limit plate is screwed around the threaded end to the required position, and then the shaft is installed on the front cover plate, and then the first limit plate and the second limit plate are respectively rotated around the two shafts to adjust the profile of the annular wall. In this way, the shaft can avoid interfering with the rotation of the first limit plate around the threaded end, that is, the problem of mechanical interference in the process of screwing the first limit plate relative to the threaded end is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 A schematic diagram of a first-person perspective of a centrifugal fan volute for testing provided in this application;

[0019] Figure 2 A schematic diagram of a second perspective of a centrifugal fan volute for testing provided in this application;

[0020] Figure 3 A front view of a centrifugal fan volute for testing provided in this application;

[0021] Figure 4 for Figure 3 Sectional view at AA;

[0022] Figure 5 An axonometric view of the adjustment mechanism provided for this application;

[0023] Figure 6 An exploded view of a rotating shaft in an embodiment provided in the present application.

[0024] Figure numerals: 100, test centrifugal fan volute; 10, front cover; 11, positioning hole; 12, arc-shaped through hole; 20, rear cover; 30, annular wall; 40, adjustment mechanism; 41, rotating shaft; 411, connecting block; 411a, positioning protrusion; 411b, positioning groove; 412, magnet; 412a, through hole; 413, plastic scale; 413a, scale line; 413b, positioning block; 42, adjusting rod; 421, threaded end; 43, first limit plate; 431, identification portion; 44, second limit plate; 50, sealing gasket; 51, avoidance groove. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0026] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it may be directly on the other component or there may also be a central component. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may be a central component at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in the specification of this application are for illustrative purposes only and do not represent the only implementation method.

[0027] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0028] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first feature is directly in contact with the second feature, or the first feature and the second feature are indirectly in contact through an intermediate medium. Moreover, a first feature being “above”, “above” or “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below” or “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0029] Unless otherwise defined, all technical and scientific terms used in the specification of this application have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in the specification of this application includes any and all combinations of one or more related listed items.

[0030] See also Figure 1 , Figure 2 and Figure 5 The present application provides a centrifugal fan volute 100 for testing. Figure 1 A schematic diagram of a first-person perspective of a centrifugal fan volute for testing provided in this application; Figure 2 A schematic diagram of a second perspective of a centrifugal fan volute for testing provided in this application; Figure 5 Axonometric view of the adjustment mechanism provided for this application.

[0031] The test centrifugal fan volute 100 includes a front cover plate 10, a rear cover plate 20, an annular wall 30 and a plurality of adjustment mechanisms 40. The annular wall 30 is located between the front cover plate 10 and the rear cover plate 20. The plurality of adjustment mechanisms 40 are distributed at intervals along the circumference of the annular wall 30 and are used to connect the annular wall 30 to the front cover plate 10 and the rear cover plate 20 and to adjust the profile of the annular wall 30. Each adjustment mechanism 40 includes a rotating shaft 41, an adjustment rod 42, and a first limit plate 43 and a second limit plate 44 respectively connected to both ends of the adjustment rod 42. The first limit plate 43 is located on the side of the front cover plate 10 away from the rear cover plate 20, and the second limit plate 44 is located on the side of the rear cover plate 20 away from the front cover plate 10. At least one end of the adjustment rod 42 is configured as a threaded end 421, and the threaded end 421 is threadedly connected to the first limit plate 43 or the second limit plate 44. The number of rotating shafts 41 is configured to be two, the first limiting plate 43 is rotatably connected to the front cover plate 10 around one of the rotating shafts 41, the second limiting plate 44 is rotatably connected to the rear cover plate 20 around the other rotating shaft 41, and the rotating shaft 41 corresponding to the threaded end 421 is configured to be detachably connected to the front cover plate 10 or the rear cover plate 20.

[0032] That is to say, the adjustment mechanism 40 can be arranged in the following three forms.

[0033] Embodiment 1

[0034] like Figure 1 As shown, one end of the adjusting rod 42 is configured as a threaded end 421, and the threaded end 421 is threadedly connected to the first limiting plate 43, and the rotating shaft 41 on the first limiting plate 43 is detachably connected to the front cover plate 10, and the other end of the adjusting rod 42 is fixedly connected to the second limiting plate 44, and the connection method between the rotating shaft 41 on the second limiting plate 44 and the rear cover plate 20 is not limited.

[0035] Embodiment 2

[0036] One end of the adjusting rod 42 is configured as a threaded end 421, which is threadedly connected to the second limiting plate 44, and the rotating shaft 41 on the second limiting plate 44 is detachably connected to the rear cover 20. The other end of the adjusting rod 42 is fixedly connected to the first limiting plate 43, and the connection method between the rotating shaft 41 on the first limiting plate 43 and the rear cover 20 is not limited.

[0037] Embodiment 3

[0038] Both ends of the adjusting rod 42 are configured as threaded ends 421, one of the threaded ends 421 is threadedly connected to the first limit plate 43, and the rotating shaft 41 on the first limit plate 43 is detachably connected to the front cover 10, and the other threaded end 421 is threadedly connected to the second limit plate 44, and the rotating shaft 41 on the second limit plate 44 is detachably connected to the rear cover 20.

[0039] The following takes the first embodiment as an example to introduce the structure of the adjustment mechanism 40 and the principle of the adjustment mechanism 40 connecting the annular wall 30 to the front cover plate 10 and the rear cover plate and adjusting the profile of the annular wall 30 .

[0040] By screwing the first limiting plate 43 threadedly connected thereto around the threaded end 421, the spacing between the first limiting plate 43 and the second limiting plate 44 can be adjusted, so that the first limiting plate 43 can cooperate with the second limiting plate 44 to clamp the annular wall 30 between the front cover plate 10 and the rear cover plate 20, that is, the annular wall 30 is firmly connected between the front cover plate 10 and the rear cover plate 20. In addition, by rotating the first limiting plate 43 and the second limiting plate 44 around the two rotating shafts 41 respectively, the position of the adjusting rod 42 relative to the first limiting plate 43 and the second limiting plate 44 can be adjusted, and then the different positions of the annular wall 30 along the circumferential direction are limited by a plurality of adjusting rods 42 spaced apart along the circumferential direction of the annular wall 30 to adjust the profile of the annular wall 30. Furthermore, by configuring the rotating shaft 41 on the first limit plate 43 to be detachably connected to the corresponding front cover plate 10, the adjustment process of the adjustment mechanism 40 can be: first, after the first limit plate 43 is screwed around the threaded end 421 to the required position, the rotating shaft 41 is installed on the front cover plate 10, and then the first limit plate 43 and the second limit plate 44 are respectively rotated around the two rotating shafts 41 to adjust the profile of the annular wall 30. In this way, it is possible to avoid the rotating shaft 41 interfering with the rotation of the first limit plate 43 around the threaded end 421, that is, the problem of mechanical interference in the process of screwing the first limit plate 43 relative to the threaded end 421 is solved.

[0041] Furthermore, the other end of the non-threaded end 421 of the adjusting rod 42 is welded to the second limiting plate 44. The rotating shaft 41 is arranged at the axis of the first limiting plate 43, and the other rotating shaft 41 is arranged at the axis of the second limiting plate 44. The front cover plate 10 and the rear cover plate 20 are respectively provided with an arc-shaped through hole 12 extending around the rotating shaft 41, and the arc-shaped through hole 12 is used to pass the adjusting rod 42.

[0042] In one embodiment, the rotating shaft 41 on the first limiting plate 43 is connected to the front cover plate 10 by magnetic adsorption. Since the ring wall 30 moves along the inner side of the front cover plate 10 during the adjustment of the profile of the ring wall 30, the inner side of the front cover plate 10 needs to be as flat as possible to avoid interference with the movement of the ring wall 30. Compared with detachable connection methods such as riveting, screw connection or clamping, in this embodiment, the rotating shaft 41 on the first limiting plate 43 is connected to the front cover plate 10 by magnetic adsorption, which will not affect the flatness of the inner side of the front cover plate 10.

[0043] Optionally, see Figure 3 , Figure 4 and Figure 6 ,in, Figure 3 A front view of a centrifugal fan volute for testing provided in this application; Figure 4 for Figure 3 Sectional view at AA; Figure 6 An exploded view of a rotating shaft in an embodiment provided in the present application.

[0044] The rotating shaft 41 includes a connecting block 411 and a magnet 412 , wherein one end of the magnet 412 is connected to the connecting block 411 , and the other end is used to attract the front cover 10 . The magnet 412 is bonded to the connecting block 411 .

[0045] Alternatively, in other embodiments, the rotating shaft 41 may also be configured as a whole magnet.

[0046] For further information, please refer to Figure 4 and Figure 6 The connection block 411 has a positioning protrusion 411a, the magnet 412 has a through hole 412a, the front cover 10 has a positioning hole 11, and the positioning protrusion 411a is used to penetrate the through hole 412a and be inserted into the positioning hole 11. In this way, the positioning protrusion 411a cooperates with the positioning hole 11 to play a positioning role, so that the rotating shaft 41 can be quickly and accurately installed at the desired position on the front cover 10.

[0047] In one embodiment, the cross-sectional shape of the positioning protrusion 411a matches the shape of the positioning hole 11 and is used to limit the connection block 411 from rotating relative to the front cover plate 10 or the rear cover plate 20. In this way, it can be ensured that the rotating shaft 41 is installed on the front cover plate 10 and is stationary relative to the front cover plate.

[0048] Alternatively, if Figure 6 As shown, the cross section of the positioning protrusion 411 a is in the shape of an elongated strip, and the positioning hole 11 is configured as a racetrack-shaped hole corresponding to the positioning protrusion 411 a.

[0049] Alternatively, in other embodiments, the cross-section of the positioning protrusion 411a may also be triangular, rectangular, or other irregular polygonal shapes, and the shape of the positioning hole 11 matches the cross-sectional shape of the positioning protrusion 411a, so that the rotating shaft 41 can also be prevented from rotating.

[0050] like Figure 4 As shown, the test centrifugal fan volute 100 also includes a sealing gasket 50, which is sandwiched between the front cover plate 10 and the annular wall 30, and between the rear cover plate 20 and the annular wall 30. The sealing gasket 50 is provided with an avoidance groove 51, which is connected to the positioning hole 11 and is used to avoid the positioning protrusion 411a. The sealing gasket 50 is used to seal the front cover plate 10 and the annular wall 30, and to seal the rear cover plate 20 and the annular wall 30. By providing the avoidance groove 51 on the sealing gasket 50, the avoidance groove 51 can reserve a deformation margin for the sealing gasket 50 facing the positioning hole 11, thereby preventing this part of the sealing gasket 50 from being deformed toward the positioning hole 11 after being squeezed, and pushing the positioning protrusion 411a in the positioning hole 11 out of the positioning hole 11.

[0051] like Figure 1 Figure 5 and Figure 6 As shown, the rotating shaft 41 is relatively stationary with the front cover plate 10 or the rear cover plate 20, and a scale line 413a is provided on the surface of the rotating shaft 41, and an identification portion 431 is provided on the first limit plate 43 and the second limit plate 44 respectively corresponding to the scale line 413a, and the identification portion 431 is used to cooperate with the scale line 413a to record the rotation angle of the first limit plate 43 around the rotating shaft 41 relative to the front cover plate 10, or the identification portion 431 is used to cooperate with the scale line 413a to record the rotation angle of the second limit plate 44 around the rotating shaft 41 relative to the rear cover plate 20.

[0052] Optionally, in one embodiment, if Figure 6 As shown, the rotating shaft 41 also includes a plastic scale sheet 413, which is fixedly connected to the connecting block 411, and the scale lines 413a are opened on the plastic scale sheet 413. In this embodiment, by providing the plastic scale sheet 413, it is easier to process and form dense and high-precision scale lines 413a on the plastic scale sheet 413. Specifically, the scale lines 413a can be formed by 3D printing. Among them, the scale lines 413a are set on the surface of the plastic scale sheet 413 away from the connecting block 411.

[0053] Alternatively, in other embodiments, the scale line 413 a may be directly opened on the surface of the connecting block 411 .

[0054] Furthermore, one of the plastic scale sheet 413 and the connecting block 411 is provided with a positioning groove 411b, and the other is provided with a positioning block 413b, and the positioning block 413b is used to engage with the positioning groove 411b. In this way, the positioning block 413b is used to not only play the role of assembly positioning with the positioning groove 411b, but also can fix the plastic scale sheet 413 to the connecting block 411.

[0055] Furthermore, the plastic scale piece 413 is bonded to the connecting block 411 , so that the firmness of the connection between the plastic scale piece 413 and the connecting block 411 can be further improved.

[0056] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the scope of patent protection of the present application shall be subject to the attached claims.

Claims

1. A centrifugal fan volute for testing, comprising a front cover plate (10), a rear cover plate (20), an annular wall (30) and a plurality of adjustment mechanisms (40), wherein the annular wall (30) is located between the front cover plate (10) and the rear cover plate (20), and the plurality of adjustment mechanisms (40) are distributed at intervals along the circumference of the annular wall (30) and are used to connect the annular wall (30) to the front cover plate (10) and the rear cover plate (20) and to adjust the profile of the annular wall (30); It is characterized in that Each of the adjusting mechanisms (40) comprises a rotating shaft (41), an adjusting rod (42), and a first limiting plate (43) and a second limiting plate (44) respectively connected to two ends of the adjusting rod (42), wherein the first limiting plate (43) is located on a side of the front cover plate (10) away from the rear cover plate (20), and the second limiting plate (44) is located on a side of the rear cover plate (20) away from the front cover plate (10), and at least one end of the adjusting rod (42) is configured as a threaded end (421), and the threaded end (421) is threadedly connected to the first limiting plate (43) or the second limiting plate (44); The number of the rotating shafts (41) is configured to be two, the first limiting plate (43) is rotatably connected to the front cover plate (10) around one of the rotating shafts (41), and the second limiting plate (44) is rotatably connected to the rear cover plate (20) around the other rotating shaft (41); and the rotating shaft (41) corresponding to the threaded end (421) is configured to be detachably connected to the front cover plate (10) or the rear cover plate (20).

2. The test centrifugal fan volute according to claim 1, characterized in that: The rotating shaft (41) is magnetically adsorbed and connected to the front cover plate (10) or the rear cover plate (20).

3. The test centrifugal fan volute according to claim 2, characterized in that: The rotating shaft (41) comprises a connecting block (411) and a magnet (412); one end of the magnet (412) is connected to the connecting block (411), and the other end is used to adsorb the front cover plate (10) or the rear cover plate (20).

4. The test centrifugal fan volute according to claim 3, characterized in that: The connecting block (411) has a positioning protrusion (411a), the magnet (412) is provided with a through hole (412a), the front cover plate (10) or the rear cover plate (20) is provided with a positioning hole (11), and the positioning protrusion (411a) is used to penetrate the through hole (412a) and be inserted into the positioning hole (11).

5. The test centrifugal fan volute according to claim 4, characterized in that: The cross-sectional shape of the positioning protrusion (411a) matches the shape of the positioning hole (11), and is used to limit the connection block (411) from rotating relative to the front cover plate (10) or the rear cover plate (20).

6. The test centrifugal fan volute according to claim 4, characterized in that: The cross section of the positioning protrusion (411a) is in the shape of an elongated strip, and the positioning hole (11) is configured as a racetrack-shaped hole corresponding to the positioning protrusion (411a).

7. The test centrifugal fan volute according to claim 4, characterized in that: The test centrifugal fan volute further comprises a sealing gasket (50), wherein the sealing gasket (50) is sandwiched between the front cover plate (10) and the annular wall (30), and between the rear cover plate (20) and the annular wall (30); The sealing gasket (50) is provided with an avoidance groove (51), and the avoidance groove (51) is connected to the positioning hole (11) and is used to avoid the positioning protrusion (411a).

8. The test centrifugal fan volute according to claim 3, characterized in that: The rotating shaft (41) and the front cover plate (10) or the rear cover plate (20) are relatively stationary, and a scale line (413a) is provided on the surface of the rotating shaft (41), and marking parts (431) are provided on the first limiting plate (43) and the second limiting plate (44) respectively corresponding to the scale line (413a); The identification portion (431) is used to cooperate with the scale line (413a) to record the angle of rotation of the first limit plate (43) around the rotation axis (41) relative to the front cover plate (10), or the identification portion (431) is used to cooperate with the scale line (413a) to record the angle of rotation of the second limit plate (44) around the rotation axis (41) relative to the rear cover plate (20).

9. The centrifugal fan volute for testing according to claim 8, characterized in that: The rotating shaft (41) further comprises a plastic scale sheet (413), wherein the plastic scale sheet (413) is fixedly connected to the connecting block (411), and the scale line (413a) is provided on the plastic scale sheet (413).

10. The test centrifugal fan volute according to claim 9, characterized in that: One of the plastic scale sheet (413) and the connecting block (411) is provided with a positioning groove (411b), and the other is provided with a positioning block (413b), and the positioning block (413b) is used for snap-fitting with the positioning groove (411b).

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