Sealing structure of centrifugal pump

Abstract

A sealing structure of a centrifugal pump comprises a shell, a driving motor and a flow channel used for fluid circulation are arranged in the shell, the driving motor comprises a stator, a rotor and an output shaft driven by the rotor to rotate, and one end of the output shaft is exposed in the flow channel and used for being connected with an impeller. The shell is internally provided with a placing cavity for placing the rotor and the stator, the placing cavity is internally provided with an isolation sleeve, the isolation sleeve enables the inside and the outside of the placing cavity to form a first placing cavity and a second placing cavity for placing the rotor and the stator respectively, and the first placing cavity and the second placing cavity are isolated through the isolation sleeve. The beneficial effects of the utility model are that the arrangement of the isolation sleeve divides the placing cavity into the first placing cavity and the second placing cavity, thereby realizing the physical isolation between the stator and the fluid, effectively preventing the fluid (such as pumped liquid) from invading into the stator area, avoiding the short circuit or corrosion problem caused by the contact of the stator winding with the fluid, and prolonging the service life of the stator winding. Therefore, the reliability and the service life of the motor are obviously improved.

Description

Technical Field

[0001] The utility model relates to a sealing structure, in particular to a sealing structure of a centrifugal pump. Background Art

[0002] In new energy vehicles, such as electric and hybrid vehicles, the battery cooling system is a critical component for ensuring safe and efficient battery pack operation. It maintains the battery temperature within an ideal range to prevent performance degradation or thermal runaway caused by overheating. A centrifugal pump, the core driving force of this system, circulates the coolant (typically an ethylene glycol-water solution) and is used to manage heat dissipation in the battery pack. The centrifugal pump uses a brushless motor with a coaxial direct drive to drive the impeller. When the motor is activated, the impeller rotates at high speed, generating centrifugal force that draws coolant from the battery pack inlet into the pump chamber. The pressurized fluid is then transferred to an external radiator or heat exchanger for heat exchange. The cooled fluid is then recirculated back to the battery pack for continuous temperature regulation. This process operates automatically while the vehicle is driving or charging, ensuring a stable battery temperature between 20°C and 40°C, thereby enhancing battery life and overall vehicle efficiency. The entire system features a compact design that fits within the vehicle's tight confines, and its flow and pressure parameters are monitored in real time by an electronic control unit (ECU).

[0003] However, while existing centrifugal pumps achieve high efficiency through a narrow air gap between the stator and rotor of a brushless motor, their leak-proof structure between the motor cavity and the pump chamber has significant deficiencies. This structure utilizes a dynamic sealing system composed of rubber parts, including a dynamic seal and a static seal mounted on the shaft. During rotation, the dynamic seal gradually moves toward the static seal and abuts against it to form a seal. A flow hole is provided to prevent fluid from invading the dynamic and static seals, obstructing sealing contact, and to slow the time it takes for fluid to enter the motor. However, this design places extremely high demands on the machining precision and assembly process of the sealing components, and even the slightest carelessness can lead to assembly deviations. Furthermore, the rubber material is susceptible to wear and aging during long-term relative motion, significantly shortening its service life and reducing its sealing effectiveness, which can lead to coolant intrusion into the motor. This not only increases maintenance costs but also potentially impacts the reliability of the battery cooling system. Utility Model Content

[0004] In view of the deficiencies in the prior art, the utility model provides a sealing structure of a centrifugal pump with better sealing effect.

[0005] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows: A sealing structure of a centrifugal pump, comprising a shell, a driving motor and a flow channel for fluid circulation provided in the shell, the driving motor comprising a stator, a rotor and an output shaft driven to rotate by the rotor, one end of the output shaft being exposed in the flow channel and used to connect to an impeller, a placement cavity for placing the rotor and stator provided in the shell, an isolation sleeve provided in the placement cavity, the isolation sleeve forming a first placement cavity and a second placement cavity for placing the rotor and stator inside and outside the placement cavity respectively, the first placement cavity and the second placement cavity being isolated by the isolation sleeve.

[0006] The beneficial effects of the present invention are as follows: by providing an isolation sleeve to separate the placement chamber into a first placement chamber (for placing the rotor) and a second placement chamber (for placing the stator), physical isolation between the stator and the fluid is achieved, effectively preventing fluid (such as pumped liquid) from invading the stator area, avoiding short circuits or corrosion problems in the stator winding due to contact with the fluid, thereby significantly improving the reliability and service life of the motor. At the same time, the isolation sleeve adopts a static seal structure (rather than providing a dynamic seal on the output shaft), which simplifies the overall design, reduces manufacturing costs and maintenance difficulties; the static seal has more stable sealing performance and reduces the risk of fluid leakage, making it particularly suitable for applications with high-pressure or corrosive fluids. In addition, this design can also reduce pump vibration and noise, because the isolation sleeve, as a fixed component, avoids mechanical wear and imbalance problems that may be caused by dynamic seals. As a preferred embodiment, the isolation sleeve can be constructed as a thin-walled stainless steel cylinder, secured to the inner wall of the placement chamber by welding or flange connection. This structure ensures the penetration of magnetic flux while providing sufficient mechanical strength and pressure resistance, ensuring complete isolation between the first and second placement chambers. The inner and outer surfaces of the isolation sleeve can be polished to reduce fluid flow resistance and enhance corrosion resistance. As a preferred embodiment, the isolation sleeve is made of a non-magnetic material (such as austenitic stainless steel or titanium alloy), which maintains magnetic coupling efficiency while resisting fluid erosion. The isolation sleeve can be centrally installed to evenly distribute sealing pressure, thereby preventing deformation or rupture of the isolation sleeve during high-speed operation of the pump.

[0007] Furthermore, the two end surfaces of the isolation sleeve facing the inner wall of the placement cavity are respectively embedded in the placement cavity and form a sealed connection with the placement cavity.

[0008] This technical solution enhances the stability and sealing reliability of the isolation sleeve by embedding the end face of the isolation sleeve into the placement cavity to form a sealed connection. The embedded design allows the isolation sleeve to fit tightly with the shell structure, avoiding loosening or displacement caused by vibration or thermal expansion of the pump body, thereby ensuring long-term effective isolation between the first placement cavity and the second placement cavity, and preventing the fluid from penetrating into the stator area from the end gap. This structure also simplifies the assembly process, reduces the need for additional fixings, and reduces manufacturing costs. At the same time, the embedded connection improves the rigidity of the overall structure, helps to disperse mechanical stress, and prolongs the service life of the pump. As a preferred method, the embedded part of the isolation sleeve can adopt a stepped flange structure and match the corresponding groove on the inner wall of the placement cavity, and achieve initial fixation through interference fit; the sealed connection can be completed by coating an elastic sealant on the flange surface or setting a pre-loaded gasket, so that a reliable seal can be formed by applying axial pressure during assembly without the need for complex tools. As a preferred method, the inner wall of the placement cavity can be designed as a conical groove with a guiding bevel, and the end face of the isolation sleeve is correspondingly set as a conical boss. During installation, the self-locking principle of the cone surface is used to achieve automatic centering and expansion, ensuring uniform contact of the sealing surface, thereby maintaining the sealing integrity under high temperature or high pressure conditions.

[0009] Furthermore, sealing grooves are provided on both end surfaces of the placement cavity facing the isolation sleeve, and the cross-section of the sealing groove overlaps with the portion of the isolation sleeve embedded in the placement cavity. A sealing member is provided in the sealing groove, and the sealing member is tightly arranged between the isolation sleeve and the inner wall of the placement cavity.

[0010] This technical solution achieves enhanced sealing of the embedded part of the isolation sleeve by providing a sealing groove on the end face of the placement cavity and installing a seal. The overlapping design of the sealing groove and the embedded part ensures that the sealing force acts directly on the embedded area of ​​the isolation sleeve, effectively blocking the fluid penetration path and improving the sealing effect; the expansion setting of the seal can compensate for manufacturing tolerances and thermal deformation, maintain long-term sealing stability, and avoid leakage caused by pump body vibration or temperature changes. This structure also simplifies maintenance, the seal is easy to replace, and downtime is reduced. In addition, the overlapping cross-section design optimizes pressure distribution, reduces local stress concentration, and extends component life. As a preferred method, the sealing groove can be designed as a rectangular or V-shaped cross-section with a width slightly smaller than the diameter of the seal to provide pre-compression space; the seal is preferably an O-ring rubber ring or a metal C-ring, which is radially expanded by axial compression during installation to fill the micro-gap between the isolation sleeve and the placement cavity, thereby achieving dynamic sealing. As a preferred method, the inner wall of the sealing groove can be provided with rough texture or micro grooves to increase the friction coefficient with the seal and prevent the seal from shifting under the impact of high-pressure fluid; in terms of working principle, when the pump is running, the fluid pressure acts on the seal, causing it to further expand and tighten, forming a self-reinforcing sealing effect, ensuring its reliable operation.

[0011] Furthermore, the first insertion cavity is communicated with the flow channel.

[0012] This technical solution allows the fluid to directly contact the rotor by connecting the first insertion chamber with the flow channel, providing an efficient cooling mechanism. When the impeller is working, the fluid is sucked into or discharged from the flow channel, and part of the fluid enters the first insertion chamber and continues to flow through the surface of the rotor, taking away the heat generated by the rotor, thereby controlling the temperature rise and preventing efficiency loss or component damage caused by overheating. This design does not require an additional cooling system, simplifies the pump structure, and reduces energy consumption; at the same time, the fluid circulation can also lubricate the rotor bearings, reduce wear, and improve overall efficiency. In addition, in low-temperature fluid applications, the thermal expansion problem of the rotor material can be avoided. As a preferred method, the connecting structure can be designed to open a plurality of radial through holes on the side wall of the shell, evenly distributed at the interface between the first insertion chamber and the flow channel to ensure uniform flow of the fluid; a filter can be installed in the through hole to prevent impurities from entering and affecting the operation of the rotor. As a preferred method, the connecting path is in the form of a spiral guide groove, which is integrated on the inner wall of the placement cavity. When the fluid flows into the flow channel, the guide groove guides the fluid to form a vortex, thereby enhancing the heat exchange efficiency and reducing the flow resistance. In terms of working principle, when the fluid passes through the guide groove, it flushes the rotor surface and the heat is quickly dissipated through convection, thereby stabilizing the rotor temperature.

[0013] Furthermore, after the stator is energized, the magnetic lines of force penetrate the isolation sleeve and act on the rotor.

[0014] This technical solution ensures that the isolation sleeve does not interfere with magnetic force transmission, allowing the magnetic field generated by the stator to effectively penetrate the isolation sleeve to drive the rotor, maintaining efficient motor operation. This avoids magnetic loss or efficiency loss caused by the introduction of the isolation sleeve, ensuring the pump's output power and response speed. Furthermore, the magnetic flux penetration design simplifies motor control, eliminating the need for additional compensation circuitry and improving system reliability. Furthermore, it supports contactless transmission, reduces mechanical wear, and is suitable for high-speed or heavy-load conditions. Preferably, the isolation sleeve can be made of a high-permeability non-ferromagnetic material, such as 316L stainless steel or Hastelloy, to reduce eddy current losses. Its surface can be annealed to optimize the lattice structure and ensure low-resistance penetration of magnetic flux. Preferably, the isolation sleeve is designed as a thin-walled cylinder with axial or circumferential flux-enhancing grooves (such as a shallow groove array) to guide and concentrate the magnetic flux. In principle, when the stator coil is energized, the magnetic field is directly coupled to the rotor permanent magnets through the thin-walled region of the isolation sleeve. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is an axonometric diagram of an embodiment of the present utility model;

[0016] Figure 2 This is a disassembly diagram of an embodiment of the utility model;

[0017] Figure 3A cross-sectional view of an embodiment of the present utility model;

[0018] Figure 4 This is an axonometric view of the drive motor and isolation sleeve according to an embodiment of the present utility model;

[0019] Figure 5 This is a disassembled diagram of the drive motor and isolation sleeve according to an embodiment of the present utility model. DETAILED DESCRIPTION

[0020] The sealing structure of a centrifugal pump in the embodiment of the present invention is as follows Figure 1-5 As shown, the housing 1 includes a drive motor 2 and a flow channel 3 for fluid circulation. The drive motor 2 includes a stator 21, a rotor 22, and an output shaft 23 driven by the rotor 22. One end of the output shaft 23 is exposed in the flow channel 3 and is used to connect to an impeller 231. The impeller 231 is a pump impeller assembly in the prior art and is used to drive the fluid flow. The housing 1 also includes a placement chamber 4 for the rotor 22 and stator 21. The placement chamber 4 is provided with an isolation sleeve 5. The isolation sleeve 5 forms a first placement chamber 41 for the rotor 22 and a second placement chamber 42 for the stator 21 inside and outside the placement chamber 4, respectively. The first placement chamber 41 and the second placement chamber 42 are separated by the isolation sleeve 5, thereby effectively preventing fluid from invading the stator 21 area. The two end faces of the isolation sleeve 5 facing the inner wall of the placement chamber 4 are embedded in the placement chamber 4 and form a sealed connection with the placement chamber 4. The two end faces of the placement chamber 4 facing the isolation sleeve 5 are provided with sealing grooves 51. The cross section of the sealing groove 51 overlaps with the portion of the isolation sleeve 5 embedded in the placement chamber 4. The sealing groove 51 is provided with a sealing member 52. The sealing member 52 is tightened and arranged between the isolation sleeve 5 and the inner wall of the placement chamber 4 to achieve a stable and reliable sealing effect. The first insertion chamber 41 is connected to the flow channel 3 to facilitate the entry of fluid into it when the pump is working to cool the rotor 22. The isolation sleeve 5 is made of non-magnetic material. The magnetic lines of force generated by the stator 21 after being energized can penetrate the isolation sleeve 5 and act on the rotor 22 to ensure the normal operation of the motor.

[0021] When the centrifugal pump is started, the stator 21 of the drive motor 2 is energized to generate a rotating magnetic field. The magnetic lines of force pass through the isolation sleeve 5 and act on the rotor 22, driving the rotor 22 and the output shaft 23 to rotate. The output shaft 23 drives the impeller 231 to rotate in the flow channel 3, promoting the flow of fluid. Due to the isolation effect of the isolation sleeve 5, the fluid can only enter the first insertion chamber 41 through the flow channel 3, while the second insertion chamber 42 remains dry, avoiding fluid contact with the stator 21 winding and preventing short-circuit damage; at the same time, the fluid continues to cool the rotor 22 in the first insertion chamber 41 to control its temperature rise. The static sealing structure of the isolation sleeve 5 achieves efficient sealing through the expansion of the seal 52 in the sealing groove 51, which is more reliable and low-cost than dynamic sealing.

[0022] The above embodiment is only one preferred embodiment of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention are all included in the protection scope of the present invention.

Claims

1. A centrifugal pump sealing structure, comprising a housing, a drive motor and a flow channel for fluid circulation disposed within the housing, the drive motor comprising a stator, a rotor, and an output shaft driven for rotation by the rotor, one end of the output shaft being exposed in the flow channel and connected to an impeller, characterized in that: A placement cavity for placing the rotor and the stator is provided in the shell, and an isolation sleeve is provided in the placement cavity. The isolation sleeve forms a first placement cavity and a second placement cavity for placing the rotor and the stator inside and outside the placement cavity respectively, and the first placement cavity and the second placement cavity are isolated by the isolation sleeve.

2. The sealing structure of a centrifugal pump according to claim 1, characterized in that: The two end surfaces of the isolation sleeve facing the inner wall of the placement cavity are respectively embedded in the placement cavity and form a sealed connection with the placement cavity.

3. The sealing structure of a centrifugal pump according to claim 2, characterized in that: The placement cavity is provided with sealing grooves on both end surfaces facing the isolation sleeve, and the cross section of the sealing groove overlaps with the portion of the isolation sleeve embedded in the placement cavity. A sealing member is provided in the sealing groove, and the sealing member is tightly arranged between the isolation sleeve and the inner wall of the placement cavity.

4. The sealing structure of a centrifugal pump according to claim 1, characterized in that: The first insertion cavity is communicated with the flow channel.

5. The sealing structure of a centrifugal pump according to claim 1, characterized in that: After the stator is energized, the magnetic lines of force penetrate the isolation sleeve and act on the rotor.

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