Centrifugal fan capable of improving stress condition of bearing

Abstract

A centrifugal fan capable of improving the stress condition of a bearing comprises a main shaft, an impeller and a volute, the volute comprises an air duct bent plate provided with an air outlet, the two sides of the air duct bent plate are covered with an air inlet side plate and a transmission side plate respectively, an air inlet is formed in the air inlet side plate, and the main shaft is arranged in a through hole of the transmission side plate in a penetrating mode and connected with the impeller. The main shaft is sleeved with a sealing shaft disc, the sealing shaft disc and the transmission side plate form a transmission side cavity through a comb tooth sealing structure, then the transmission side cavity is communicated with a low-pressure air inlet area of the air inlet through an air guide pipe, and a low-pressure balance area can be formed in the transmission side cavity relative to a high-pressure air outlet area in the volute. The pressure difference between the low-pressure air inlet area and the high-pressure air outlet area can generate axial force towards the air inlet side plate on the impeller and the main shaft, the pressure difference between the two sides of the sealing shaft disc can generate axial force towards the transmission side plate on the sealing shaft disc and the main shaft, the two axial forces are opposite in direction, the stress condition of the bearing is remarkably improved, the service life of the bearing is prolonged, and the service life of the bearing is prolonged. And the fan failure rate is reduced.

Description

Technical Field

[0001] The utility model relates to the field of centrifugal fans, in particular to a centrifugal fan capable of improving the stress condition of a bearing. Background Art

[0002] Centrifugal fans are widely used in various industries of the national economy. In industrial production, due to the influence of factors such as the working environment, operating conditions and the structural characteristics of the fan itself, centrifugal fans often experience various mechanical failures in long-term operation. Among them, bearing failure accounts for a large proportion of the total failures of centrifugal fans. When the centrifugal fan is in operation, the impeller works on the airflow, making the pressure on the outlet side of the fan much greater than that on the inlet side, resulting in a large pressure difference. The pressure difference acts on the impeller to generate axial force, and the axial force of the impeller acts on the main shaft, and finally all acts on the main shaft bearings. Therefore, the bearings must bear all the axial forces and the radial forces inherent in the operation of the fan rotor. Therefore, the bearings are subjected to complex forces, harsh working conditions, easy wear and high failure rates. It is necessary to reduce the axial force borne by the bearings and improve the bearing stress conditions in order to increase the service life of the bearings and reduce the failure rate of the fan. Utility Model Content

[0003] In order to solve the problem in existing centrifugal fans that the main shaft bearings are easily damaged by axial forces due to pressure difference, the utility model provides a centrifugal fan capable of improving the bearing stress condition.

[0004] The utility model adopts the following technical solution to solve the above technical problems: a centrifugal fan capable of improving the bearing stress condition, comprising a main shaft, an impeller and a volute, the volute comprising a duct bend plate with an air outlet, an air inlet side plate and a transmission side plate on both sides of the duct bend plate, the impeller is located inside the volute, the air inlet side plate is provided with an air inlet, the main shaft is passed through the through hole of the transmission side plate and is connected to the impeller, a sealing shaft disc is provided on the main shaft, the outer circumference of the sealing shaft disc is provided with a circle of outer sealing teeth, the transmission side plate is located inside the volute A circle of inner sealing teeth is provided on the side, and the outer sealing teeth of the sealing shaft disc and the inner sealing teeth of the transmission side plate cooperate to form a comb tooth sealing structure, so that the side of the sealing shaft disc away from the impeller cooperates with the transmission side plate to form a transmission side cavity. An air duct is connected to the transmission side plate, one end of the air duct is connected to the transmission side cavity, and the other end of the air duct extends from the outside of the volute to the air inlet, and is connected to the low-pressure air inlet area inside the air inlet, so that a low-pressure balance area matching the low-pressure air inlet area can be formed in the transmission side cavity relative to the high-pressure air outlet area inside the volute.

[0005] Preferably, a step surface facing the main shaft is provided in the middle of the transmission side plate, and the inner sealing teeth are provided on the inner side of the step surface.

[0006] According to the above technical solution, the beneficial effects of the utility model are:

[0007] The centrifugal fan of the utility model is provided with a sealing shaft disc on the main shaft. The sealing shaft disc and the transmission side plate form a transmission side cavity through a comb-teeth sealing structure, and the transmission side cavity is connected to the air inlet through the air guide duct. When the fan is running and the main shaft drives the impeller to rotate, a low-pressure air inlet area is formed inside the air inlet because the impeller continuously works on the airflow, and a high-pressure air outlet area is formed inside the volute. The pressure difference between the low-pressure air inlet area and the high-pressure air outlet area acts on the impeller, which will generate an axial force toward the air inlet side plate on the impeller and the main shaft. Since a low-pressure balance area can be formed in the transmission side cavity, a pressure difference will also be generated on both sides of the sealing shaft disc, which will generate an axial force toward the transmission side plate on the sealing shaft disc and the main shaft. The two axial forces are in opposite directions. Under their interaction, the axial force originally acting on the bearing will be significantly reduced or completely offset, thereby significantly improving the stress condition of the bearing, increasing the service life of the bearing, and reducing the failure rate of the fan. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a cross-sectional schematic diagram of the utility model;

[0009] Figure 2 for Figure 1 A partial enlarged view of the sealing shaft disc area.

[0010] Markings in the figure: 1. Main shaft, 2. Impeller, 3. Air duct bend plate, 4. Air inlet side plate, 5. Transmission side plate, 6. Air inlet, 7. Sealing shaft disc, 8. External sealing teeth, 9. Internal sealing teeth, 10. Air guide duct. DETAILED DESCRIPTION

[0011] With reference to the accompanying drawings, the specific implementation is as follows:

[0012] like Figure 1 、 2 As shown, a centrifugal fan capable of improving bearing stress conditions includes a main shaft 1, an impeller 2 and a volute. The volute includes a duct bend plate 3 with an air outlet, and the two sides of the duct bend plate 3 are respectively covered with an air inlet side plate 4 and a transmission side plate 5. The impeller 2 is located inside the volute, and the air inlet side plate 4 is installed with an air inlet 6. The main shaft 1 is passed through the through hole of the transmission side plate 5 and is connected to the impeller 2. When the main shaft 1 drives the impeller 2 to rotate, the air flow will flow into the interior of the volute from the air inlet 6, and will be pressurized by the rotation of the impeller 2 before flowing out from the air outlet. Therefore, a low-pressure air inlet area will be formed inside the air inlet 6, and a high-pressure air outlet area will be formed inside the volute. The pressure difference between the low-pressure air inlet area and the high-pressure air outlet area acts on the impeller 2, which will generate an axial force on the impeller 2 and the main shaft 1 toward the air inlet side plate 4.

[0013] like Figure 1 、 2As shown, the main shaft 1 is fitted with a sealing disc 7, the outer circumference of which is provided with a circle of outer sealing teeth 8. The middle portion of the transmission side plate 5 is provided with a stepped surface facing the main shaft 1, and the inner side of the stepped surface is provided with a circle of inner sealing teeth 9. The outer sealing teeth 8 of the sealing disc 7 and the inner sealing teeth 9 of the transmission side plate 5 cooperate to form a comb-teeth sealing structure, so that the side of the sealing disc 7 away from the impeller 2 cooperates with the transmission side plate 5 to form a transmission side cavity. Figure 2 As shown, there is a gap between the inner hole of the transmission side plate 5 and the main shaft 1, but the amount of air that can flow through the gap is extremely small, so the transmission side cavity can be regarded as a closed space.

[0014] like Figure 1 、 2 As shown, an air duct 10 is connected to the transmission side plate 5, one end of the air duct 10 is connected to the transmission side cavity, and the other end of the air duct 10 extends from the outside of the volute to the air inlet 6, and is connected to the low-pressure air inlet area inside the air inlet 6. Therefore, the air pressure in the transmission side cavity will be close to or consistent with the low-pressure air inlet area, so that a low-pressure balance area matching the low-pressure air inlet area can be formed in the transmission side cavity relative to the high-pressure air outlet area inside the volute. Therefore, the side of the sealing shaft disc 7 facing the impeller 2 is the high-pressure air outlet area, and the side of the sealing shaft disc 7 facing the transmission side plate 5 is the low-pressure balance area. A pressure difference will also be generated on both sides of the sealing shaft disc 7, which will generate an axial force towards the transmission side plate 5 on the sealing shaft disc 7 and the main shaft 1. Therefore, the main shaft 1 will be subjected to two axial forces in opposite directions at the same time. Under their interaction, the axial force acting on the bearing of the main shaft 1 will be significantly reduced or completely offset, significantly improving the stress condition of the bearing, increasing the service life of the bearing, and reducing the failure rate of the fan.

Claims

1. A centrifugal fan capable of improving bearing stress conditions, characterized in that: The invention comprises a main shaft (1), an impeller (2) and a volute, wherein the volute comprises an air duct curved plate (3) with an air outlet, and the two sides of the air duct curved plate (3) are respectively covered with an air inlet side plate (4) and a transmission side plate (5), the impeller (2) is located inside the volute, and the air inlet side plate (4) is provided with an air inlet (6), the main shaft (1) is passed through a through hole of the transmission side plate (5) and is connected to the impeller (2), a sealing shaft disc (7) is sleeved on the main shaft (1), and a circle of outer sealing teeth (8) is provided on the outer circumferential surface of the sealing shaft disc (7), a circle of inner sealing teeth (9) is provided on one side of the transmission side plate (5) located inside the volute, and the sealing shaft disc ( The outer sealing teeth (8) of the impeller (7) and the inner sealing teeth (9) of the transmission side plate (5) cooperate to form a comb-tooth sealing structure, so that the side of the sealing shaft disc (7) away from the impeller (2) cooperates with the transmission side plate (5) to form a transmission side cavity, and an air guide duct (10) is connected to the transmission side plate (5), one end of the air guide duct (10) is connected to the transmission side cavity, and the other end of the air guide duct (10) extends from the outer side of the volute to the air inlet (6) and is connected to the low-pressure air inlet area inside the air inlet (6), so that a low-pressure balance area matching the low-pressure air inlet area can be formed in the transmission side cavity relative to the high-pressure air outlet area inside the volute.

2. A centrifugal fan capable of improving bearing stress according to claim 1, characterized in that: A step surface facing the main shaft (1) is provided in the middle of the transmission side plate (5), and the inner sealing teeth (9) are arranged on the inner side of the step surface.

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