Axial permanent magnetic levitation magnetic force transmission pump

Abstract

This invention discloses an axial permanent magnet levitation magnetic drive pump, comprising a pressure-bearing component consisting of a pump body, a pump cover, and an isolation sleeve. The pump shaft is housed within the pressure-bearing component, and a sliding bearing supporting the pump shaft is located within the pump cover. An impeller and an inner magnetic rotor are connected to both ends of the pump shaft, respectively. An outer magnetic rotor, corresponding to the inner magnetic rotor, is connected to one end of a drive shaft. The other end of the drive shaft is connected to a matching motor. An isolation sleeve is provided between the inner and outer magnetic rotors. An axial permanent magnet levitation bearing is located within the pressure chamber. The axial permanent magnet levitation bearing includes a static magnetic component and a moving magnetic component. The static magnetic component includes multiple annular static magnetic rings arranged axially and a static magnetic encapsulation sleeve covering their surface. The moving magnetic component includes multiple annular moving magnetic rings arranged axially and a moving magnetic encapsulation sleeve covering their surface. This invention, through magnetic coupling of a special magnetic circuit, withstands the axial forces generated by impeller hydraulics and rotor self-weight, thereby improving the long-term stability of the magnetic drive pump operation.

Description

Technical Field

[0001] This invention belongs to the field of magnetic pump technology, and in particular relates to an axial permanent magnet levitation magnetic drive pump. Background Technology

[0002] Magnetic drive pumps are fluid transport machines that rely on permanent magnet non-contact transmission technology to solve the leakage problems of traditional dynamic seal pumps. Currently, magnetic drive pumps are widely used in the petroleum and petrochemical industries and in the field of special liquid transportation, effectively solving the safety and environmental impact of leaks in the transportation of flammable, explosive, and toxic liquids. These industries also have high reliability requirements for the equipment used, demanding long-term reliable operation; the API 685 standard requires reliable operation for at least 3 years of continuous operation. However, because magnetic drive pumps use a sealed isolation sleeve to disconnect the shaft of traditional dynamic seal pumps, the internal shaft is immersed in the transported medium. The internal rotor needs to be supported by medium-lubricated bearings to maintain the rotation center and axial position. But most media have very low viscosity and poor lubricity, requiring various force balancing methods to reduce or even eliminate the force on the medium-lubricated bearings to ensure reliability. In particular, axial force is a significant concern. Due to the different surface areas of the two impeller discs in a centrifugal pump, the pressure exerted on the front and rear cover plates during impeller operation results in substantial axial force. Therefore, magnetic pumps are designed with an axial force balancing structure to address this issue. For example, Chinese patent document CN2486753Y discloses a magnetic drive pump that uses a balancing hole and an enlarged rear sealing ring, with an axial throttling ring added in the middle to act as a balancing disc. When subjected to axial force, the clearance of the axial throttling ring changes, causing a change in the pressure difference across this clearance, thereby altering the pressure in the pressure regulating zone and automatically balancing the hydraulic axial force, preventing stress on the thrust bearing. Chinese patent document CN201148979Y discloses an axial force self-balancing magnetic drive multistage centrifugal pump that uses impellers placed back-to-back to cancel out the axial forces on the impellers in both directions, achieving balance. These hydraulic balancing schemes are suitable for single-stage closed-loop centrifugal pumps and multi-stage impeller pumps with a small impeller inlet diameter compared to the impeller outer diameter. However, for single-stage high specific speed mixed-flow pumps and axial-flow pumps with a large impeller inlet-to-impeller outer diameter ratio, especially mixed-flow pumps where the impeller rear cover outer diameter is smaller than the impeller inlet diameter, and two-stage impeller centrifugal pumps with different inlet sizes, the impeller front cover area is too small or even nonexistent, making it impossible to generate hydraulic thrust towards the drive end. No matter how the structure is designed, it cannot balance its own hydraulic axial force. Therefore, the above-mentioned hydraulic balancing schemes cannot be used to eliminate the force on the thrust bearing. Thrust bearings that rely on medium lubrication obviously cannot withstand such a large axial force due to the very low viscosity of the medium, and cannot operate reliably for a long time. As a result, there are currently no magnetic pumps of this type on the open market.

[0003] Chinese patent document CN2437877Y discloses a rare-earth permanent magnet magnetic levitation high-power magnetic pump. It employs an annular magnet on the rotor and a magnet of the same pole on the lower part of the axially corresponding base, relying on the repulsion of like poles to support the rotor and reduce the stress on the radial bearing. This magnetic bearing is used to reduce the stress on the radial bearing, not as a replacement, because the stiffness of permanent magnet magnetic bearings is relatively low and cannot fully maintain the high-precision radial positioning required for rotor rotation. The axial thrust bearing described in this patent is still a conventional thrust sliding bearing. In addition, Chinese patent document CN107100878A discloses a magnetic pump with magnetic levitation bearings, comprising a pump body, impeller, permanent magnet thrust ring, permanent magnet rotor, electromagnetic bearing, bearing positioning sleeve, controller, pump cover, bearing seat, connecting frame, pump shaft, outer magnetic rotor, isolation sleeve, inner magnetic rotor, and motor; the bearing seat is fitted between the pump shaft and the connecting frame, with a first electromagnetic bearing and a second electromagnetic bearing respectively at both ends; the pump shaft is sequentially fitted with a first permanent magnet thrust ring, a first permanent magnet rotor, a second permanent magnet rotor, and a second permanent magnet thrust ring; the two permanent magnet rotors are in a suspended state and never contact the two electromagnetic bearings; the two permanent magnet thrust rings are in a suspended state and never contact the two electromagnetic bearings. The magnetic pump with magnetic levitation bearings provided by this invention solves the structural defects of traditional magnetic pumps, enabling the two pairs of friction pairs in the pump to have non-contact, non-frictional wear, no lubrication required, and high speed characteristics during operation, thereby improving the service life of the magnetic pump. However, it mainly uses electromagnetic levitation technology to solve the wear of the thrust ring, which has a relatively complex structure. Moreover, the bearing needs to be connected to the circuit in a flammable and explosive medium, which does not meet the explosion-proof requirements and is difficult to apply in flammable and explosive media, thus its practicality is not strong. At the same time, this patent also requires the placement of a position feedback sensor in the medium pressure chamber, which makes control difficult and implementation difficult. The electromagnetic levitation bearing requires electricity, and once the power is accidentally lost, the rotor will be directly rubbed by the force, which will cause the bearing to be damaged. Therefore, its reliability and practicality are poor, and the cost is high.

[0004] Traditional permanent magnet thrust bearings employ an axially magnetized, plane-to-plane magnetic circuit with opposite poles. They consist of a moving magnetic disk mounted on the rotor and a stationary magnetic disk mounted on the base. The magnetic field is axial, relying on the principle of like poles repulsion to withstand axial forces. Because the rotor requires bidirectional thrust to maintain a stable axial position, two pairs of back-to-back or face-to-face moving and stationary magnetic disks are needed. The magnetic forces acting on the two moving magnetic disks are in opposite directions. When the distance between the pairs of disks is equal, the total axial magnetic force is zero, meaning the rotor is in its original position. Once the rotor is subjected to axial force and moves to one side, the distance between the pair of magnetic poles on one side decreases, increasing the magnetic force on the moving disk; conversely, the distance between the pair of magnetic poles on the other side increases, decreasing the magnetic force on the moving disk. The total magnetic force is opposite to the direction of the force until a stable position is reached. However, because the magnetic forces acting on the two moving magnetic disks are in opposite directions, part of the magnetic thrust force on one side is canceled out by the magnetic thrust force on the other side, resulting in low magnetic efficiency and low magnet utilization. Moreover, the magnetic force is proportional to the disk area, and a certain disk diameter is required to withstand a certain magnetic force. Since the disk is located in the liquid being transported, the friction loss between the disk and the liquid is proportional to the 4th to 5th power of the diameter, resulting in large rotational friction loss and low efficiency. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an axial permanent magnet levitation magnetic drive pump. Through magnetic coupling, it can withstand the axial forces generated by impeller hydraulics and rotor self-weight, eliminating the need for traditional mechanical load-bearing thrust bearings or complex, expensive, unreliable, and unsafe electromagnetic levitation bearings. This expands the applicability of magnetic pumps and improves their long-term stability and reliability.

[0006] An axial permanent magnet levitation magnetic drive pump includes a pressure-bearing housing composed of a pump body, a pump cover, and an isolation sleeve. The pump shaft is disposed inside the pressure-bearing housing. A sliding bearing supporting the pump shaft is provided inside the pump cover. An impeller and an inner magnetic rotor are respectively connected to both ends of the pump shaft. An outer magnetic rotor corresponding to the inner magnetic rotor is connected to one end of a drive shaft. The other end of the drive shaft is connected to a matching motor. An isolation sleeve is provided between the inner magnetic rotor and the outer magnetic rotor. The pump is characterized in that an axial permanent magnet levitation bearing is provided in the pressure chamber of the pressure-bearing housing.

[0007] The axial permanent magnet suspension bearing includes a static magnetic component fixed to the pump cover and a moving magnetic component fixed to the pump shaft. Both the static magnetic component and the moving magnetic component are cylindrical. The static magnetic component includes multiple annular static magnetic rings arranged along the axial direction and a static magnetic encapsulation sleeve covering the surface of the annular static magnetic rings. The moving magnetic component includes multiple annular moving magnetic rings arranged along the axial direction and a moving magnetic encapsulation sleeve covering the surface of the annular moving magnetic rings.

[0008] Each annular static magnetic ring and annular moving magnetic ring has the same axial width; both annular static magnetic rings and annular moving magnetic rings are radially magnetized, and the polarities of adjacent annular static magnetic rings and adjacent annular moving magnetic rings are opposite; the number of annular static magnetic rings and annular moving magnetic rings is the same, and in the free state without external force, the polarities of the annular static magnetic rings and annular moving magnetic rings facing each other are opposite.

[0009] In this invention, when the pump is not operating, the annular moving magnetic ring in the moving magnetic component is coupled to the annular stationary magnetic ring in the stationary magnetic component due to the attraction of opposite magnetic poles. The annular moving magnetic ring and the annular stationary magnetic ring are directly opposite each other, and the rotor has no axial displacement. During operation, the pump shaft is subjected to axial force and moves axially. The moving magnetic component rotates with the pump shaft and moves axially under the action of hydraulic force. At this time, the annular moving magnetic ring in the moving magnetic component will generate axial displacement relative to the annular stationary magnetic ring in the stationary magnetic component, causing the moving and stationary magnetic poles to shift. The magnetic pole of each annular moving magnetic ring is attracted by the opposite magnetic pole of the annular stationary magnetic ring that was originally facing it, and at the same time, it is repelled by the like magnetic pole adjacent to it in the direction of movement. The magnetic force on each magnetic ring is twice that when there is only a single magnetic ring. The magnetic force increases rapidly, so that the annular moving magnetic ring is subjected to a large magnetic force opposite to the direction of axial displacement. The magnetic force increases with the increase of the offset, and finally stops axial movement at the equilibrium position of magnetic force and axial force, thereby realizing the function of a thrust bearing.

[0010] The static magnetic component also includes a bearing housing, which is fixed to the pump cover, and the static magnetic sleeve is sealed to the bearing housing by welding;

[0011] The moving magnetic component also includes a rotor base, which is fixed to the pump shaft, and the moving magnetic sleeve is sealed to the rotor base by welding.

[0012] Preferably, the operating gap between the stationary magnetic component and the moving magnetic component is 0.3–3 mm. By setting this operating gap, it is ensured that the stationary and moving components do not collide and operate reliably, while also increasing the magnetic field strength at the operating gap and reducing the use of magnetic materials.

[0013] Preferably, there are at least two annular stationary magnetic rings and two annular moving magnetic rings, and the axial width of each annular stationary magnetic ring and annular moving magnetic ring is 5 to 15 times the operating clearance. The specific number depends on the magnitude of the axial force. Compared with a single magnetic ring with the same total axial width, the magnetic force is greater. Each magnetic ring can generate twice the maximum magnetic force, and a small axial displacement can generate a large thrust magnetic force, resulting in higher magnet utilization.

[0014] Preferably, the radial thickness of the annular static magnetic ring and the annular moving magnetic ring are equal, and the thickness is 2 to 10 times the operating gap depending on the magnitude of the force, which ensures both a small volume and a high utilization rate of magnetic materials.

[0015] Preferably, each annular static magnet and annular moving magnet are assembled from multiple sector-shaped permanent magnets in the same radial magnetization direction, with each permanent magnet having the same radial thickness, which facilitates magnetization and manufacturing.

[0016] Furthermore, the permanent magnet is a rare earth permanent magnet such as neodymium iron boron or samarium cobalt.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. This invention uses an axial permanent magnet magnetic levitation bearing in a conventional centrifugal magnetic pump to replace the conventional mechanical thrust bearing, which is prone to wear and damage from starting impact. Through magnetic non-contact coupling, it can fully bear the axial force generated by impeller hydraulics and rotor self-weight, thereby improving the operational reliability of the conventional centrifugal magnetic pump.

[0019] 2. By applying axial permanent magnet magnetic levitation bearings, traditional dynamic seal pumps such as mixed flow pumps, axial flow pumps, and asymmetric two-stage centrifugal pumps that cannot use hydraulic axial force balancing can be converted into leakage-free magnetic drive pumps. At the same time, the non-contact thrust ensures long-term operational reliability.

[0020] 3. The cylindrical multi-magnetic-coil alternating magnetic pole magnetic circuit of the present invention can maintain a stable axial alignment position of the pump rotor when it is stopped and not subjected to hydraulic axial force. It also has the advantage of generating a larger bearing magnetic force than the traditional magnetic circuit. When subjected to hydraulic axial force, it can stabilize the rotor in a suitable position with less displacement, avoid excessive axial displacement of the rotor affecting the hydraulics, and ensure the normal work of the impeller.

[0021] 4. The cylindrical magnetic circuit of the present invention can increase the number of magnetic rings and expand along the axial direction according to the magnitude of the axial force, without the need to increase the diameter, thereby minimizing the friction loss between the magnetic pump and the liquid being transported during operation and reducing the operating loss of the magnetic pump.

[0022] 5. The axial permanent magnet levitation magnetic bearing using the cylindrical magnetic circuit of the present invention has no limitation on radial diameter and can be installed at a suitable position inside the magnetic pump. It makes full use of the existing rotation space inside the magnetic pump for conformal installation, so that the external structural dimensions remain basically unchanged and no or little additional disc friction loss from friction with the liquid medium is generated. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the cantilevered axial permanent magnet levitation magnetic drive pump structure in an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of one structure of the axial permanent magnet suspension bearing in this invention;

[0025] Figure 3This is a schematic diagram of another structure of the axial permanent magnet suspension bearing in this invention;

[0026] Figure 4 This is a diagram showing the arrangement of the cylindrical magnetic circuit in this invention;

[0027] Figure 5 This is a schematic diagram of the magnetic ring assembly structure in an axial permanent magnet levitation magnetic bearing.

[0028] Figure 6 This is a schematic diagram of the structure of the axial permanent magnet levitation magnetic drive pump with two-end support in Embodiment 2 of the present invention. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be noted that the embodiments described below are intended to facilitate the understanding of the present invention and do not constitute any limitation thereof.

[0030] Example 1

[0031] like Figure 1 As shown, this embodiment is a cantilevered axial permanent magnet levitation magnetic drive pump, including a hydrodynamic component consisting of an impeller and a pump body. The impeller 2 is mounted on the pump shaft 11 and located inside the pump body 1, with its opening sealed by a pump cover 3 connected to the pump body 1. A medium-lubricated sliding bearing 10 is installed inside the pump cover 3 to maintain the rotation center of the rotor. An inner magnetic rotor 6 is mounted on one end of the pump shaft 11, and an outer magnetic rotor 5 is connected to one end of the drive shaft. The other end of the drive shaft is connected to a matching motor 7. The motor 7 serves as the power input component, driving the rotation and causing the inner magnetic rotor 6 located in the pressure chamber of the isolation sleeve 4 to rotate together, thereby driving the coaxial impeller 2 to perform work.

[0032] A unique axial magnetic levitation bearing is installed between the pump cover 3 and the pump shaft 11. The static magnetic component 9 is fixed on the pump cover 3, and the moving magnetic component 8 is fixed on the rotor. The two have a radial operating gap of 0.3 to 3 mm to achieve non-contact load bearing.

[0033] like Figure 2 As shown, the static magnetic component 9 includes a bearing housing 91, multiple annular static magnetic rings 92, and a static magnetic enclosure 93. The surfaces of the multiple annular static magnetic rings 92 are covered by the static magnetic enclosure 93, and the ends of the static magnetic enclosure 93 are sealed to the bearing housing 91 by welding. The bearing housing 91 is fixed to the pump cover 3.

[0034] The moving magnetic component 8 includes a rotor base 81, multiple annular moving magnetic rings 82, and a moving magnetic enclosure 83. The surfaces of the multiple annular moving magnetic rings 82 are covered by the moving magnetic enclosure 83, and the ends of the moving magnetic enclosure 83 are sealed to the rotor base 81 by welding. The rotor base 81 is fixed to the pump shaft 11.

[0035] The static magnetic component 9 and the moving magnetic component 8 are mutually matched cylindrical shapes. Figure 2 In this configuration, the static magnetic component 9 is on the inner side, and the moving magnetic component 8 is on the outer side. Alternatively, the static magnetic component 9 can be on the outer side, and the moving magnetic component 8 can be on the inner side, as shown below. Figure 3 As shown.

[0036] like Figure 4 As shown, the axial width of each annular static magnetic ring 92 and annular moving magnetic ring 82 is equal; both the annular static magnetic ring 92 and the annular moving magnetic ring 82 are radially magnetized, and the polarities of adjacent annular static magnetic rings 92 and adjacent annular moving magnetic rings 82 are opposite, that is, the N / S poles are alternately arranged along the axial direction; the number of annular static magnetic rings 92 and annular moving magnetic rings 82 is the same, and the polarities of the annular static magnetic rings 92 and annular moving magnetic rings 82 facing each other are opposite when in a free state without external force.

[0037] like Figure 5 As shown, each magnetic ring can be assembled from multiple sector-shaped permanent magnets 12 of the same grade and magnetic properties in the same radial magnetization direction. Each permanent magnet 12 has the same radial thickness and is made of rare earth permanent magnets such as neodymium iron boron or samarium cobalt.

[0038] When the pump is not working, the annular moving magnetic ring 82 in the moving magnetic component 8 is coupled to the annular static magnetic ring 92 in the static magnetic component 9 due to the attraction of opposite magnetic poles. The annular moving magnetic ring 82 and the annular static magnetic ring 92 are directly opposite each other, and the rotor has no axial displacement. When the pump is running, the pump shaft 11 is subjected to axial force and moves axially. The moving magnetic component 8 rotates and moves axially with the pump shaft 11. At this time, the annular moving magnetic ring 82 in the moving magnetic component 8 will undergo axial displacement relative to the annular stationary magnetic ring 92 in the stationary magnetic component 9, resulting in magnetic pole offset. The magnetic pole of each annular moving magnetic ring 82 is attracted by the opposite magnetic pole originally facing the annular stationary magnetic ring 92, and at the same time, it is repelled by the like magnetic pole adjacent to the magnetic pole in the direction of movement. The magnetic force on each magnetic ring is twice that when there is only a single magnetic ring. The magnetic force increases rapidly, so that the annular moving magnetic ring 82 is subjected to a large magnetic force opposite to the direction of axial displacement. The magnetic force increases with the increase of offset, and finally stops axial movement at the equilibrium position of magnetic force and axial force, thereby realizing the function of thrust bearing.

[0039] Example 2

[0040] like Figure 6 As shown, this embodiment is a two-end supported axial permanent magnet levitation magnetic drive pump. The first-stage impeller 2A and the second-stage impeller 2B are mounted on the pump shaft 11 and located inside the pump body 1. A media-lubricated radial sliding bearing 10A at the drive end and a radial sliding bearing 10B at the suction end are installed inside the pump cover 3 to maintain the rotor's rotation center.

[0041] The primary impeller 2A has a larger inlet diameter than the secondary impeller 2B, making it unable to self-balance the axial force. The axial force is borne by a permanent magnet axial suspension bearing, as described below.

[0042] In the axial permanent magnet levitation magnetic drive pump with two-end support, a unique axial magnetic levitation bearing is installed between the pump cover 3 and the pump shaft 11. The static magnetic component 9 is fixedly mounted on the pump cover 3, and the moving magnetic component 8 is fixedly mounted on the rotor. The two have a radial operating clearance of 0.3 to 3 mm to achieve non-contact load bearing. Through magnetic coupling, it bears the axial force generated by the impeller hydraulic force and the rotor's own weight.

[0043] The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An axial permanent magnet levitation magnetic drive pump, comprising a pressure-bearing housing composed of a pump body, a pump cover, and an isolation sleeve, wherein a pump shaft is disposed within the pressure-bearing housing, a sliding bearing supporting the pump shaft is provided within the pump cover, an impeller and an inner magnetic rotor are respectively connected to both ends of the pump shaft, an outer magnetic rotor corresponding to the inner magnetic rotor is connected to one end of a drive shaft, the other end of the drive shaft is connected to a matching motor, and an isolation sleeve is provided between the inner magnetic rotor and the outer magnetic rotor, characterized in that, An axial permanent magnet suspension bearing is installed inside the pressure chamber of the pressure-bearing shell. The axial permanent magnet suspension bearing includes a static magnetic component fixed to the pump cover and a moving magnetic component fixed to the pump shaft. Both the static and moving magnetic components are cylindrical. The static magnetic component includes multiple annular static magnetic rings arranged axially and a static magnetic encapsulation sleeve covering the surface of the annular static magnetic rings. The moving magnetic component includes multiple annular moving magnetic rings arranged axially and a moving magnetic encapsulation sleeve covering the surface of the annular moving magnetic rings. The number of annular static and moving magnetic rings is at least two. The axial width of each annular static and moving magnetic ring is 5 to 15 times the operating clearance. The radial thickness of the annular static and moving magnetic rings is equal, which is 2 to 10 times the operating clearance. Each annular static and moving magnetic ring is assembled from multiple sector-shaped permanent magnets in the same radial magnetization direction, and each permanent magnet has the same radial thickness. The operating clearance between the static and moving magnetic components is 0.3 to 3 mm. Each annular static magnetic ring and annular moving magnetic ring has the same axial width; both annular static magnetic rings and annular moving magnetic rings are radially magnetized, and the polarities of adjacent annular static magnetic rings and adjacent annular moving magnetic rings are opposite; the number of annular static magnetic rings and annular moving magnetic rings is the same, and in the free state without external force, the polarities of the annular static magnetic rings and annular moving magnetic rings facing each other are opposite. When the pump is running, the annular moving magnetic ring in the moving magnetic component is axially displaced relative to the annular stationary magnetic ring in the stationary magnetic component, causing the magnetic poles to shift. Each annular moving magnetic ring's magnetic pole is attracted by the opposite magnetic pole originally facing the annular stationary magnetic ring, while simultaneously being repelled by the same magnetic pole adjacent to that pole in the direction of movement. The magnetic force increases as the shift increases, and eventually stops axially moving at the equilibrium position of the magnetic force and axial force, thus realizing the function of the thrust bearing.

2. The axial permanent magnet levitation magnetic drive pump according to claim 1, characterized in that, The static magnetic component also includes a bearing housing, which is fixed to the pump cover, and the static magnetic sleeve is sealed to the bearing housing by welding; The moving magnetic component also includes a rotor base, which is fixed to the pump shaft, and the moving magnetic sleeve is sealed to the rotor base by welding.

3. The axial permanent magnet levitation magnetic drive pump according to claim 1, characterized in that, The permanent magnet is made of rubidium iron boron or samarium cobalt.

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