A balanced high-speed centrifugal fan

Abstract

The present invention discloses a balanced high-speed centrifugal fan, which includes a motor, a first-stage volute and a second-stage volute respectively arranged on the first end face pump cover and the second end face pump cover of the motor. A first-stage impeller and a second-stage impeller connected to the first end and the second end of the motor rotor are respectively arranged inside the first-stage volute and the second-stage volute. The first-stage impeller and the second-stage impeller are installed back to back. The outlet of the first-stage volute is connected to the inlet of the second-stage volute through a connecting pipe. A first bearing structure and a second bearing structure are respectively arranged at positions of the motor rotor close to the first end and the second end. A balance drum is arranged on the rotor section between the second bearing structure and the second-stage impeller. A high-pressure chamber is formed in the region between the first end face of the balance drum and the rear cover plate of the second-stage impeller. A low-pressure chamber is formed in the region between the second end face of the balance drum and the second end face pump cover of the motor. There is a gap between the outer cylindrical surface of the balance drum and the inner wall of the shaft hole of the second end face pump cover. A vent hole is arranged on the second end face pump cover.

Description

Technical Field

[0001] The present invention relates to the field of centrifugal fans, and particularly to a balanced high-speed centrifugal fan. Background Art

[0002] For current high-speed centrifugal fans, especially those with a rotational speed above 8000 r / min, due to the limitations of the bearing's ultimate rotational speed and axial force, magnetic levitation or air-floating bearings are generally used, which makes the manufacturing technology complex and the cost very high, restricting their popularization and promotion. For example, there is a high-speed two-stage centrifugal blower based on air dynamic pressure bearings disclosed in the Chinese Patent Grant Publication No. CN208417019U. This patent uses air dynamic pressure bearings to balance the axial force and has the above-mentioned disadvantages of complex technology, high cost, and restricted popularization and promotion. Summary of the Invention

[0003] The purpose of the present invention is to provide a balanced high-speed centrifugal fan to solve the above problems in view of the above-mentioned deficiencies and defects of the prior art.

[0004] The technical problems solved by the present invention can be achieved by the following technical solutions:

[0005] A balanced high-speed centrifugal fan includes a motor, a first-stage volute and a second-stage volute respectively arranged on the first-end pump cover and the second-end pump cover of the motor. A first-stage impeller and a second-stage impeller connected to the first end and the second end of the motor rotor are respectively arranged in the first-stage volute and the second-stage volute. The first-stage impeller and the second-stage impeller are installed back to back. The outlet of the first-stage volute is connected to the inlet of the second-stage volute through a connecting pipe. A first bearing structure and a second bearing structure are respectively arranged at positions of the motor rotor close to the first end and the second end. A balance drum is arranged on the rotor section between the second bearing structure and the second-stage impeller. A high-pressure chamber is formed in the region between the first end face of the balance drum and the rear cover plate of the second-stage impeller. A low-pressure chamber is formed in the region between the second end face of the balance drum and the second-end pump cover of the motor. There is a gap connecting the high-pressure chamber and the low-pressure chamber between the outer circular surface of the balance drum and the inner wall of the shaft hole of the second-end pump cover. A vent hole is arranged on the second-end pump cover.

[0006] In a preferred embodiment of the present invention, the vent hole is connected to the air inlet of the first-stage volute.

[0007] In a preferred embodiment of the present invention, a number of uniformly distributed spiral seal grooves are machined on the outer circular surface of the balance drum.

[0008] In a preferred embodiment of the present invention, the pitch of a single spiral seal groove is equal to the height of the balance drum, the wrap angle of the spiral seal groove is 360°, and the spiral direction of the spiral seal groove is opposite to the spiral direction of the second-stage impeller.

[0009] In a preferred embodiment of the present invention, the depth of the spiral seal groove is 0.5 - 1 mm, the width of the spiral seal groove is 3 - 5 mm, and the clearance is 0.3 - 0.7 mm.

[0010] In a preferred embodiment of the present invention, the first end face of the balance drum is in tight contact with the middle hub end face of the secondary impeller, and the second end face of the balance drum is in tight contact with the stepped structure on the motor rotor.

[0011] In a preferred embodiment of the present invention, the outer diameters and the inlet inner diameters of the primary impeller and the secondary impeller are equal or not much different, so that the pressure generated by the secondary impeller is slightly greater than that generated by the primary impeller, and the axial force on the secondary impeller is slightly greater than the axial force on the primary impeller, and the axial force acting on the fan is balanced.

[0012] In a preferred embodiment of the present invention, both the first bearing structure and the second bearing structure are high-speed thrust ceramic ball bearings or other forms of high-speed ball bearings that can meet the rated speed requirements.

[0013] In a preferred embodiment of the present invention, a corrugated pressure spring washer is provided on the outer ring of the first bearing structure.

[0014] Due to the adoption of the above technical solutions, in the present invention, by providing a balance drum, the requirement for the rotational speed of the bearing under the same design working conditions is reduced, and the axial force received by the bearing is balanced. In addition, the present invention can also adopt ordinary high-speed thrust ceramic ball bearings or other forms of high-speed ball bearings that can meet the rated speed requirements, the fan structure is simpler, the production cost is reduced, and thus it becomes possible to widely promote and apply the high-speed fan in various industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0016] Figure 1 It is a schematic cross-sectional view of an embodiment of the present invention.

[0017] Figure 2 It is a schematic structural view of an embodiment of the present invention.

[0018] Figure 3 It is Figure 1 The enlarged view at position a of

[0019] Figure 4 It is Figure 3 The enlarged view at position b of

[0020] Figure 5 is Figure 3 an enlarged view of part c of

[0021] Figure 6 is the front view of the balance drum according to an embodiment of the present invention.

[0022] Figure 7 is the schematic structural view of the balance drum according to an embodiment of the present invention. Detailed implementation manners

[0023] In order to make the technical means, creative features, achieved purposes and functions of the present invention easy to understand, the present invention will be further described below.

[0024] Refer to Figures 1 to 7 a balanced high-speed centrifugal fan shown in the figure, which includes a motor 104, a first-stage volute 110 and a second-stage volute 112 respectively arranged on the first end face pump cover 107 and the second end face pump cover 101 of the motor 104. The outlet of the first-stage volute 110 is connected to the inlet of the second-stage volute 112 through a connecting pipe 111. A first-stage impeller 108 and a second-stage impeller 100 are respectively arranged in the first-stage volute 110 and the second-stage volute 112. The first-stage impeller 108 and the second-stage impeller 100 are respectively fixed to the first end and the second end of the motor rotor 109. In this embodiment, the first-stage impeller 108 and the second-stage impeller 100 are installed back-to-back. The outer diameters and the inner diameters of the inlets of the first-stage impeller 108 and the second-stage impeller 100 are equal or not much different, so that the pressure generated by the second-stage impeller 100 is slightly greater than the pressure generated by the first-stage impeller 108, and the axial force on the second-stage impeller 100 is slightly greater than the axial force on the first-stage impeller 108. The axial force acting on the fan is balanced. It is found in the prototype production that the requirement for the rotational speed of the bearing is lower, and more than 75% to 80% of the axial force of the fan can be balanced by the back-to-back installed impellers, which can make the bearing have a longer service life.

[0025] A first bearing structure 106 and a second bearing structure 103 are respectively arranged at the positions of the motor rotor 109 close to the first end and the second end. In this embodiment, both the first bearing structure 106 and the second bearing structure 103 are high-speed thrust ceramic ball bearings, and the fan structure is simpler, reducing the production cost. Of course, the first bearing structure 106 and the second bearing structure 103 can also be other forms of high-speed ball bearings that meet the rated rotational speed requirements. In order to further balance the axial force of the first bearing structure 106, a pre-tightening force is applied to the bearing, and a corrugated pressure spring washer 105 is arranged on the outer ring of the first bearing structure 106.

[0026] A balance drum 102 is provided on the rotor section between the second bearing structure 103 and the second-stage impeller 100. Specifically, the first end face of the balance drum 102 is in tight contact with the middle hub end face 100a of the second-stage impeller 100, and the second end face of the balance drum 102 is in tight contact with the stepped structure 109a on the motor rotor 109. A high-pressure chamber P1 is formed in the region between the first end face of the balance drum 102 and the rear cover plate of the second-stage impeller 100, and a low-pressure chamber P2 is formed in the region between the second end face of the balance drum 102 and the second end face pump cover 101 of the motor 104. There is a gap b1 connecting the high-pressure chamber P1 and the low-pressure chamber P2 between the outer circumferential surface of the balance drum 102 and the inner wall of the shaft hole of the second end face pump cover 101. A vent hole d is provided on the second end face pump cover 101, and the vent hole d is communicated with the air inlet of the first-stage volute 110. Since the air inlet of the first-stage volute 110 in this embodiment is communicated with the outside atmosphere, the vent hole d in this embodiment is directly set as a through-hole structure.

[0027] A number of uniformly distributed spiral seal grooves 102a are machined on the outer circumferential surface of the balance drum 102. The number of the spiral seal grooves 102a is preferably 3 to 5. The number of the spiral seal grooves 102a in this embodiment is 3. The pitch H of a single spiral groove is equal to the height B of the balance drum, and the wrap angle of the spiral seal groove 102a is 360°. The pitch H and the wrap angle of the spiral seal groove 102a should not be too large. If they are too large, it will increase the power consumption and manufacturing cost. The spiral direction of the spiral seal groove 102a is opposite to the rotation direction of the second-stage impeller 100, which plays a role in reducing the axial force. If the spiral direction of the spiral seal groove 102a is the same as the rotation direction of the second-stage impeller 100, the axial force will increase and the leakage amount will also increase. The shape of the spiral seal groove 102a can be V-shaped, U-shaped, rectangular, etc. Considering the convenience of machining, the rectangular shape is adopted in this embodiment. The rectangular size should not be too large, otherwise it will increase the power consumption. Therefore, the depth h1 of the spiral seal groove 102a in this embodiment is 0.5 to 1 mm, the width b2 of the spiral seal groove 102a is 3 to 5 mm, and the gap b1 is 0.3 to 0.7 mm.

[0028] The spiral seal groove 102a is used to prevent the gas in the high-pressure chamber P1 from leaking to the low-pressure chamber P2, and the remaining axial force is balanced by the balance drum 102. Due to the reasons of production and manufacturing, there will still be 2 - 5% of the residual axial force after balancing by the double-stage impeller and the balance drum 102. This part of the axial force can directly act on the bearing.

[0029] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A balanced high-speed centrifugal fan, comprising a motor, a first-stage volute and a second-stage volute respectively arranged on the first end face pump cover and the second end face pump cover of the motor. A first-stage impeller and a second-stage impeller connected to the first end and the second end of the motor rotor are respectively arranged in the first-stage volute and the second-stage volute. The first-stage impeller and the second-stage impeller are installed back to back. The outlet of the first-stage volute is connected to the inlet of the second-stage volute through a connecting pipe. A first bearing structure and a second bearing structure are respectively arranged at positions of the motor rotor close to the first end and the second end. It is characterized in that, A balance drum is arranged on the rotor section between the second bearing structure and the secondary impeller. The area between the first end face of the balance drum and the rear cover plate of the secondary impeller forms a high-pressure chamber. The area between the second end face of the balance drum and the second end face pump cover of the motor forms a low-pressure chamber. There is a gap connecting the high-pressure chamber and the low-pressure chamber between the outer cylindrical surface of the balance drum and the inner wall of the shaft hole of the second end face pump cover. A vent hole is arranged on the second end face pump cover; A number of uniformly distributed spiral sealing grooves are machined on the outer cylindrical surface of the balance drum; The pitch of a single spiral sealing groove is equal to the height of the balance drum, the spiral sealing groove has a wrap angle of 360°, and the spiral direction of the spiral sealing groove is opposite to the rotation direction of the secondary impeller; The depth of the spiral sealing groove is 0.5 - 1 mm, the width of the spiral sealing groove is 3 - 5 mm, and the gap is 0.3 - 0.7 mm; The first end face of the balance drum is in tight contact with the middle hub end face of the secondary impeller, and the second end face of the balance drum is in tight contact with the stepped structure on the motor rotor; The outer diameters and inlet inner diameters of the primary impeller and the secondary impeller are equal or not much different, so that the pressure generated by the secondary impeller is slightly greater than the pressure generated by the primary impeller, and the axial force on the secondary impeller is slightly greater than the axial force on the primary impeller, and the axial force acting on the fan is balanced; The spiral sealing groove prevents the gas in the high-pressure chamber from leaking to the low-pressure chamber, and the balance drum balances the remaining axial force. Due to manufacturing reasons, there will still be a 2 - 5% residual axial force after balancing by the double-stage impeller and the balance drum. This part of the axial force can directly act on the bearing.

2. The balanced high-speed centrifugal fan according to claim 1, characterized in that, The vent hole is communicated with the air inlet of the primary volute.

3. The balanced high-speed centrifugal fan according to claim 1, wherein Both the first bearing structure and the second bearing structure are high-speed thrust ceramic ball bearings or other forms of high-speed ball bearings that can meet the rated speed requirements.

4. A balanced high-speed centrifugal fan according to claim 1, characterized in that, A corrugated pressure spring washer is arranged on the outer ring of the first bearing structure.

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