Foldable large axial flow fan impeller device and working method thereof

Abstract

The invention discloses a foldable large-scale axial flow fan impeller device and a working method thereof, and belongs to the technical field of fluid machinery, the foldable large-scale axial flow fan impeller device comprises a hub, the hub is connected with four damping blocks and four L-shaped plate mounting seats through bolt fasteners, the damping blocks are arranged below the L-shaped plate mounting seats, the L-shaped plate mounting seats are connected with L-shaped plates through rotating shafts, and the L-shaped plates are connected with the damping blocks through rotating shafts. The L-shaped plate is fixedly connected with a blade through a U-shaped clamp, the L-shaped plate drives the blade to rotate around the rotating shaft to be folded or unfolded, the blade is parallel to the axis direction of the hub in the folded state, and a preset angle is formed between the blade and the end face of the hub in the unfolded state; according to the foldable large axial flow fan impeller device adopting the structure, the time for factory disassembly and classification and the time for on-site assembly and angle adjustment are shortened; and the effectiveness of dynamic balance is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of fluid machinery, and in particular to a foldable large-scale axial flow fan impeller device and a working method thereof. Background Art

[0002] In the field of fluid machinery, large axial flow fans are used in applications requiring convenient transportation and installation, such as process air cooling, direct air cooling, and power plant cooling. However, the transportation and installation of impeller units present significant challenges. Integral impellers are expensive to transport, and diameters greater than 3m require specialized vehicles. Separate impellers, on the other hand, require disassembly of the blades and impeller after factory testing, sorting and packaging them, and then reassembly and adjustment on site. This adds significant additional work, is inefficient, and makes it difficult to ensure installation quality on site.

[0003] Furthermore, disassembling and reassembling the impeller after dynamic balancing will destroy the results of the dynamic balancing work. Furthermore, due to equipment and space limitations at the installation site, it is difficult to re-test the dynamic balance after assembly. Although it is possible to mark the corresponding locations after the dynamic balancing test and tighten the various connectors to the marked positions during on-site assembly, due to different viewing angles, it is difficult to achieve complete consistency with the pre-disassembly results, resulting in a loss of dynamic balancing accuracy.

[0004] Moreover, there are defects in the installation of blades: when the blades are installed horizontally, the installation is simplest and easy to understand, but at this time the blade root and blade shaft are subjected to large alternating loads, which can easily cause fatigue damage. In order to ensure the safety of the structure, the size of the blade root and blade shaft can only be increased, resulting in increased weight and increased cost; when the blades are installed at a fixed angle to the horizontal plane, they are only suitable for fixed speed use and have a narrow range of application; the selection of flexible blade shafts is difficult and the range of application is limited.

[0005] In summary, the existing technology has obvious deficiencies in the transportation, installation efficiency, dynamic balance maintenance and blade structure design of large axial flow fan impellers, and a new technical solution is urgently needed to solve the above problems. Summary of the Invention

[0006] The object of the present invention is to provide a foldable large-scale axial flow fan impeller device and a working method thereof, so as to solve the problems mentioned in the above background technology.

[0007] To achieve the above-mentioned objectives, the present invention provides a foldable large-scale axial flow fan impeller device, including a hub, wherein the hub is connected to four shock-absorbing blocks and four L-plate mounting seats by bolt fasteners, the shock-absorbing blocks are arranged below the L-plate mounting seats, the L-plate mounting seats are connected to the L-plate via a rotating shaft, the L-plate is fixedly connected to the blades via a U-shaped clip, and the L-plate drives the blades to rotate around the rotating shaft to fold or unfold. In the folded state, the blades are parallel to the axial direction of the hub, and in the unfolded state, the blades are at a preset angle to the end face of the hub.

[0008] Preferably, the L-plate is threadedly connected to the hub via a limiting bolt, and the limiting bolt is used to fix the position of the blade in the folded or unfolded state, wherein in the unfolded state, the end of the limiting bolt abuts against the shock-absorbing block to limit the blade angle θ, and the limiting bolt needs to be removed during the folding or unfolding operation to allow the L-plate to rotate.

[0009] Preferably, the hub is made of carbon structural steel.

[0010] Preferably, the shock absorbing block is made of damping rubber, and its damping coefficient is calculated based on the mass, rotation speed and number of blades of the fan system.

[0011] Preferably, the thickness of the shock-absorbing block is determined according to the angle θ between the blade and the end face of the hub.

[0012] Preferably, the L-plate is made of elastic steel, and the rotating shaft is made of high-strength alloy steel.

[0013] A method for operating a foldable large-scale axial flow fan impeller device comprises the following steps:

[0014] S1. Perform preliminary assembly of the device, perform force analysis on the blades, adjust the angle θ between the blades and the hub end face, and determine the thickness of the shock absorber based on the angle θ;

[0015] S2. Before leaving the factory, unfold the blades to an angle of θ and secure them with limit bolts before completing a dynamic balance test and factory inspection. After the inspection and adjustment are complete, remove the limit bolts, rotate the blades around the axis and fold them until they are parallel to the hub axis. Reinstall the limit bolts and tighten them to secure the folded state.

[0016] S3. Transport to the site, remove the limit bolts in the folded state and rotate the blades around the axis to an angle θ. Reinstall the limit bolts and check. After the inspection is correct, install the impeller to the main shaft of the axial flow fan.

[0017] Therefore, the present invention adopts a foldable large axial flow fan impeller device with the above structure and its working method, which has the following beneficial effects:

[0018] (1) Shorten the packaging time by half, ensure the product dynamic balance is consistent before and after installation, shorten the on-site installation time by half, and reduce the installation cost by a quarter.

[0019] (2) The design of the shock absorber can effectively reduce the vibration of the power system and transmission system, reduce fatigue damage at the impeller root, and increase service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1This is a schematic diagram of the single-blade impeller structure of a foldable large-scale axial flow fan impeller device of the present invention;

[0021] Figure 2 This is a force analysis diagram of a foldable large-scale axial flow fan impeller device when the blades are horizontal;

[0022] Figure 3 This is a force analysis diagram of a foldable large-scale axial flow fan impeller device after the blade angle is adjusted;

[0023] Figure 4 This is a schematic diagram of the position of the limiting bolts of a foldable large-scale axial flow fan impeller device of the present invention;

[0024] Figure 5 This is a schematic diagram of a foldable large-scale axial flow fan impeller device in a folded state;

[0025] Figure 6 This is a schematic diagram of a foldable large-scale axial flow fan impeller device in an unfolded state;

[0026] Figure numerals: 1, wheel hub; 2, shock-absorbing block; 3, L-plate; 4, rotating shaft; 5, L-plate mounting seat; 6, U-shaped clip; 7, blade; 8, limiting bolt. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0028] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the usual meanings understood by persons of ordinary skill in the field to which the present invention belongs. The words "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0029] Example

[0030] like Figure 1As shown, a foldable large-scale axial flow fan impeller device includes a hub 1, which is made of carbon structural steel. Except for the keyhole position, the other structures adopt a central symmetrical design, and the balance accuracy level is G2.5; the hub 1 is connected to four shock-absorbing blocks 2 and four L-plate mounting seats 5 by bolt fasteners, the shock-absorbing blocks 2 are arranged below the L-plate mounting seats 5, and the L-plate mounting seats 5 are connected to the L-plate 3 through the rotating shaft 4. The L-plate 3 is made of elastic steel, and the rotating shaft 4 is made of high-strength alloy steel. In this embodiment, the L-plate 3 is made of high-quality spring steel to ensure its fatigue strength. The rotating shaft 4 is made of alloy steel, and the hardness reaches HRC 50-60 after quenching and tempering, and the wear resistance is good; the L-plate 3 is fixedly connected to the blade 7 by the U-shaped clip 6, and the L-plate 3 drives the blade 7 to rotate around the rotating shaft 4 to fold or unfold. In the folded state, the blade 7 is parallel to the axial direction of the hub 1, and in the unfolded state, the blade 7 is at a preset angle to the end face of the hub 1.

[0031] The L-plate 3 is threadedly connected to the hub 1 through a limit bolt 8. The limit bolt 8 is used to fix the position of the blade 7 in the folded or unfolded state. In the unfolded state, the end of the limit bolt 8 abuts against the shock-absorbing block 2 to limit the angle θ of the blade 7. During the folding or unfolding operation, the limit bolt 8 needs to be removed to allow the L-plate 3 to rotate.

[0032] The material of the shock absorber block 2 is damping rubber, and its damping coefficient is calculated based on the mass, rotational speed and number of blades 7 of the fan system. The shock absorber block 2 should be in a relatively free state when the impeller is running stably. At this time, the bending moment load on the impeller root is minimal. Therefore, different fan models should be equipped with shock absorber blocks 2 of different thicknesses; the thickness of the shock absorber block 2 is determined according to the angle θ between the blade 7 and the end face of the hub 1.

[0033] The process of obtaining the thickness of the shock-absorbing block 2 is as follows:

[0034] When the fan is running stably, the blade 7 is mainly subjected to external forces in three directions, namely centrifugal force F 离 , gravity F 重 , and pressure F 压 , the directions of the three forces are as follows Figure 2 As shown, the size is calculated by the following formula:

[0035] F 离 =m·ω 2 ·r;

[0036] Wherein, m is the mass of the object (unit: kilogram, kg), ω is the angular velocity of rotation (unit: radian / second, rad / s), and r is the radius of rotation (the distance from the object to the rotation axis 4, unit: meter, m).

[0037] F 压 =p×A;

[0038] Where p is the pressure (unit: Pascal, Pa, i.e. N / m2 ), A is the force area (unit: square meters, m 2 ).

[0039] Among them F 压 It is constantly changing, alternating load superposition F 重 Acting on the blade shaft, it produces a variable bending moment on the blade shaft, which is easy to cause fatigue damage to the impeller root. In order to reduce its fatigue effect, the thickness of the shock absorber 2 needs to be adjusted so that the direction of the blade 7 is equal to the resultant force F of the three external forces. 合 The directions are consistent, that is, the blade 7 has an angle θ with the horizontal plane.

[0040] θ≈tan -1 [(F 重 +F 压 ) / F 高 ];

[0041] At this time, the radial force of gravity and pressure on the blade shaft is balanced by the centrifugal force, and the blade shaft only bears axial tension. Figure 3 shown.

[0042] The blades 7 are initially installed at a calculated angle, and the shock-absorbing blocks 2 and the limit bolts 8 are used to adjust the blades 7 within a certain angle range so that the centrifugal force component offsets the pressure and gravity of the blades 7. At this time, the blade shaft only bears a small part of the bending moment caused by tension and speed changes, which greatly reduces the impact of alternating loads and improves its fatigue life. At the same time, the use of the shock-absorbing blocks 2 reduces the transmission of the vibration of the blades 7 to the entire equipment, thereby expanding the applicable range of the fan speed.

[0043] A method for operating a foldable large-scale axial flow fan impeller device comprises the following steps:

[0044] S1. Perform preliminary assembly of the device, perform force analysis on the blade 7, adjust the angle θ between the blade 7 and the end face of the hub 1, and determine the thickness of the shock absorber 2 based on the angle θ;

[0045] S2. Before leaving the factory, unfold the blade 7 to the angle θ, fix it with the limit bolt 8, and complete the dynamic balance test and factory inspection. The position of the limit bolt 8 is as follows: Figure 4 As shown, after the inspection and adjustment are completed, the limiting bolt 8 is removed, and the blade 7 is rotated around the rotating shaft 4 and folded to be parallel to the axis direction of the hub 1. The limiting bolt 8 is reinstalled and tightened to fix the folded state. The folded state of the blade 7 is as shown in FIG. Figure 5 As shown;

[0046] S3, transport to the site, remove the limit bolts 8 in the folded state and rotate the blade 7 around the rotation axis 4 to an angle θ, the blade 7 is in the unfolded state as shown in FIG. Figure 6 As shown, reinstall the limit bolt 8 and check it. After the inspection is correct, install the impeller to the main shaft of the axial flow fan.

[0047] Therefore, the present invention adopts a foldable large-scale axial flow fan impeller device and its working method of the above structure, which reduces the time of factory disassembly, classification and on-site assembly and angle adjustment; and ensures the effectiveness of dynamic balancing.

[0048] Finally, it should be noted that the above embodiments are only preferred specific implementation methods of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with this technical field, within the technical scope disclosed by the present invention, can make equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A foldable large axial flow fan impeller device, characterized by: The wheel hub includes four shock-absorbing blocks and four L-plate mounting seats connected to the wheel hub by bolt fasteners. The shock-absorbing blocks are arranged below the L-plate mounting seats. The L-plate mounting seats are connected to the L-plates via rotating shafts. The L-plates are fixedly connected to blades via U-shaped clips. The L-plates drive the blades to rotate around the rotating shaft to fold or unfold. In the folded state, the blades are parallel to the axial direction of the wheel hub. In the unfolded state, the blades are at a preset angle to the end face of the wheel hub.

2. A foldable large axial flow fan impeller device according to claim 1, characterized in that: The L-plate is threadedly connected to the wheel hub via a limiting bolt, and the limiting bolt is used to fix the position of the blade in the folded or unfolded state. In the unfolded state, the end of the limiting bolt abuts against the shock-absorbing block to limit the blade angle θ. During the folding or unfolding operation, the limiting bolt needs to be removed to allow the L-plate to rotate.

3. The foldable large-scale axial flow fan impeller device according to claim 1, characterized in that: The hub is made of carbon structural steel.

4. The foldable large-scale axial flow fan impeller device according to claim 1, characterized in that: The material of the shock-absorbing block is damping rubber, and its damping coefficient is calculated based on the mass, rotation speed and number of blades of the fan system.

5. The foldable large-scale axial flow fan impeller device according to claim 4, characterized in that: The thickness of the shock-absorbing block is determined according to the angle θ between the blade and the end face of the hub.

6. The foldable large-scale axial flow fan impeller device according to claim 1, characterized in that: The L-plate is made of elastic steel, and the rotating shaft is made of high-strength alloy steel.

7. A method for operating the foldable large-scale axial flow fan impeller device according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Perform preliminary assembly of the device, perform force analysis on the blades, adjust the angle θ between the blades and the hub end face, and determine the thickness of the shock absorber based on the angle θ; S2. Before leaving the factory, unfold the blades to an angle of θ and secure them with limit bolts before completing a dynamic balance test and factory inspection. After the inspection and adjustment are complete, remove the limit bolts, rotate the blades around the axis and fold them until they are parallel to the hub axis. Reinstall the limit bolts and tighten them to secure the folded state. S3. Transport to the site, remove the limit bolts in the folded state and rotate the blades around the axis to an angle θ. Reinstall the limit bolts and check. After the inspection is correct, install the impeller to the main shaft of the axial flow fan.

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