Axial force balancing mechanism of multi-stage centrifugal pump and multi-stage centrifugal pump

Abstract

The invention discloses a multi-stage centrifugal pump axial force balance mechanism and a multi-stage centrifugal pump, the multi-stage centrifugal pump axial force balance mechanism comprises a pump shaft assembly, a bearing seat, a first balance assembly and a second balance assembly, one end of the pump shaft assembly is provided with a last-stage impeller, and the bearing seat is movably arranged on the outer side of the pump shaft assembly in a sleeving mode; a stop piece is arranged between the bearing seat and the pump shaft assembly, the first balance assembly is fixedly arranged on the outer side of the pump shaft assembly in a sleeving mode, a pressure reduction channel is arranged between the outer side wall of the first balance assembly and the inner side wall of the bearing seat, and the first balance assembly is arranged on the side, close to the last-stage impeller, of the stop piece. And the second balance assembly is fixedly arranged at the end, away from the last-stage impeller, of the pump shaft assembly in a sleeving mode and located on the outer side of the bearing seat, and an adjustable gap is formed between the second balance assembly and the stopping piece, so that the axial force eliminating effect can be remarkably improved, and meanwhile the structure is simple, and the cost is low. And the compactness of the multi-stage pump can be greatly improved.

Description

Technical Field

[0001] The present application relates to the technical field of centrifugal pumps, and further to an axial force balancing mechanism for a multi-stage centrifugal pump and a multi-stage centrifugal pump. Background Art

[0002] A multistage pump is a centrifugal pump that achieves high-pressure output by combining multiple centrifugal impellers. It generates centrifugal force through the rotation of the impeller, so that the fluid gains energy, and gradually increases the pressure and energy of the liquid through multiple stages in series. Multistage pumps are usually used in situations where high lift is required, such as urban water supply, water conservancy projects, and fire protection projects. The design of the multistage pump enables it to be efficient, energy-saving, and occupy a small area. It usually consists of an inlet section, an outlet section, a middle section, an impeller, a balancing system, a packing, a guide vane, a gland, and a bearing. Multistage pumps can transport clean water or other liquid chemicals, and the medium temperature generally does not exceed 80 degrees Celsius. In terms of application scenarios, multistage pumps are widely used in water supply and drainage systems in mines, factories, and cities, as well as various industrial applications that require high-pressure output. Its high efficiency and reliability make it an ideal choice in many industrial fields.

[0003] The axial force in a multistage pump refers to the axial force acting on the rotor during the operation of the pump due to the asymmetry of the liquid flow and the internal structure of the pump. These forces may cause the rotor to move axially and move toward the suction port, causing vibration and possibly causing friction of the impeller ring to damage the pump body, affecting the normal operation and life of the pump. Therefore, in order to eliminate the adverse effects of axial force on multistage pumps, people often use a back-to-back design of multistage impellers or set up independent axial force balancing devices. However, the existing axial force elimination effect is poor, and there are still many axial forces that cannot be eliminated. In addition, the design structure is complex, resulting in excessive size.

[0004] To this end, the present invention is dedicated to providing an axial force balancing mechanism for a multi-stage centrifugal pump and a multi-stage centrifugal pump to solve the above technical problems. Summary of the invention

[0005] In response to the above technical problems, the purpose of the present application is to provide an axial force balancing mechanism for a multi-stage centrifugal pump and a multi-stage centrifugal pump, wherein the first balancing component eliminates the axial force by reducing the pressure and abutting against the stopper, and the second balancing component further eliminates the axial force by abutting against the stopper, which can significantly improve the effect of eliminating the axial force and has a simple structure, thereby reducing the adverse effects of the balancing mechanism on the size of the multi-stage pump.

[0006] In order to achieve the above object, the present application provides an axial force balancing mechanism for a multi-stage centrifugal pump, comprising:

[0007] A pump shaft assembly, one end of which is provided with a final-stage impeller;

[0008] A bearing seat, wherein the bearing seat is movably sleeved on the outside of the pump shaft assembly so that the pump shaft assembly can rotate relative to the bearing seat, and a stopper is provided between the bearing seat and the pump shaft assembly;

[0009] A first balancing component, wherein the first balancing component is sleeved and fixed on the outside of the pump shaft component and is arranged inside the bearing seat, a decompression channel is arranged between the outer side wall of the first balancing component and the inner side wall of the bearing seat, the first balancing component is arranged on a side of the stopper close to the final-stage impeller, and an adjustable balancing chamber is formed between the stopper and the first balancing component, and the adjustable balancing chamber is communicated with both the decompression channel and the pump inlet of the bearing seat;

[0010] A second balancing component, wherein the second balancing component is sleeved and fixed on an end of the pump shaft component away from the final-stage impeller and is located on the outer side of the bearing seat, and an adjustable gap is formed between the second balancing component and the stopper;

[0011] Wherein, the pump shaft assembly is suitable for moving along the extension direction of the bearing seat to adjust the size of the adjustable balance chamber and the adjustable gap.

[0012] In some embodiments, the stopper is sleeved on the outside of the pump shaft assembly and is connected and fixed to the inner side wall of the bearing seat;

[0013] A first guide groove is arranged on a side of the stopper close to the second balancing component, and a second guide groove connected with the first guide groove is arranged on an inner wall of the stopper, and the first guide groove is used for liquid to flow in to form a liquid film between the second balancing component and the bearing seat.

[0014] In some embodiments, the first balancing assembly includes a balancing drum and a first thrust plate, and the balancing drum is sleeved and fixed on the outside of the pump shaft assembly;

[0015] A mounting groove matched with the first thrust plate is arranged on one side of the balance drum away from the last-stage impeller to fix the first thrust plate on the balance drum. The first thrust plate and the stopper are arranged correspondingly to form the adjustable gap.

[0016] In some embodiments, the second balancing assembly includes a mounting seat and a second thrust plate, wherein the mounting seat is sleeved and fixed on the outer side of an end of the pump shaft assembly away from the final stage impeller;

[0017] An inner groove matching with the second thrust plate is arranged on one side of the mounting seat close to the stopper to fix the second thrust plate on the mounting seat. The second thrust plate and the stopper are arranged correspondingly to form the adjustable balance chamber.

[0018] In some embodiments, the pump shaft assembly includes a transmission shaft and a shaft sleeve, wherein the shaft sleeve is sleeved and fixed on the outside of the transmission shaft and is arranged corresponding to the stopper;

[0019] The sides of the balance drum and the mounting seat that are close to each other are respectively connected to the two ends of the shaft sleeve in the extending direction.

[0020] In some embodiments, a labyrinth-shaped sealing groove is provided on the outer side wall of the balance drum to form the pressure relief channel.

[0021] In some embodiments, the stopper includes a first bearing and a second bearing in sequence in a direction close to the last-stage impeller, and the first bearing and the second bearing are both provided with the first guide groove and the second guide groove;

[0022] The second guide groove of the first bearing is communicated with the first guide groove of the second bearing.

[0023] In some embodiments, the first thrust plate, the second thrust plate, and the stopper are made of the same material.

[0024] In some embodiments, the adjustable gap has a size of 0.5 mm-1 mm.

[0025] A multistage centrifugal pump comprises any one of the above-mentioned multistage centrifugal pump axial force balancing mechanisms.

[0026] Compared with the prior art, the multi-stage centrifugal pump axial force balancing mechanism and the multi-stage centrifugal pump provided in the present application have the following beneficial effects:

[0027] 1. The present invention provides an axial force balancing mechanism for a multistage centrifugal pump, wherein an adjustable balancing chamber is formed between a first balancing component and a stopper, and an adjustable gap is formed between a second balancing component and a stopper. When the balancing mechanism is in different working states, the size of the adjustable balancing chamber and the adjustable gap can be adjusted as the pump shaft assembly moves. When operating at rated conditions or lower head conditions, the axial force is shared by the first balancing component and the second balancing component. The first balancing component eliminates most of the axial force by forming a pressure difference, and the second balancing component eliminates the remaining axial force by contacting and squeezing with the stopper. When operating at high head conditions, the axial force is shared by the first balancing component. While the first balancing component eliminates most of the axial force by the pressure difference, it can also contact and squeeze with the stopper to eliminate the remaining axial force, thereby significantly improving the balancing effect of the axial force. It can be seen that only the first balancing component, the second balancing component and the stopper are needed to achieve the balance of the axial force, which can significantly reduce the number of components and the difficulty and versatility of the balancing device design. Moreover, the balancing mechanism can withstand axial forces in two opposite directions, effectively reducing the axial size of the adjustable balancing chamber, thereby ensuring the compactness of the multistage pump.

[0028] 2. The present invention provides an axial force balancing mechanism for a multi-stage centrifugal pump, in which a first guide groove and a second guide groove are arranged on the stopper. The first guide groove can form a liquid film between the second balancing component and the end face of the stopper. The liquid film can reduce the direct contact between the two, prevent the occurrence of dry friction, protect the components from damage, ensure the smooth operation of the equipment, reduce wear and extend the service life. Similarly, the second guide groove can guide the liquid to between the bearing and the sleeve to play a role in lubrication, cooling and preventing dry friction.

[0029] 3. The present invention provides an axial force balancing mechanism for a multi-stage centrifugal pump, in which a sleeve is arranged on the outside of the transmission shaft, and the sleeve and the stopper are arranged correspondingly, which can provide radial support for the transmission shaft, provide higher stability and support for the high-speed rotating transmission shaft, and ensure that the transmission shaft has good coaxiality during operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The preferred implementation scheme will be described below in a clear and understandable manner with reference to the accompanying drawings to further illustrate the above-mentioned characteristics, technical features, advantages and implementation methods of the present application.

[0031] Figure 1 It is a structural schematic diagram of an axial force balancing mechanism of a multi-stage centrifugal pump provided by the present invention;

[0032] Figure 2 is a structural schematic diagram of a first balancing component provided by the present invention;

[0033] Figure 3 is a structural schematic diagram of a second balancing component provided by the present invention;

[0034] Figure 4 It is a structural schematic diagram of the bearing provided by the present invention.

[0035] Description of Figure Numbers:

[0036] Bearing seat 1, first bearing 11, second bearing 12, first guide groove 13, second guide groove 14, first balancing assembly 2, adjustable balancing chamber 21, balancing drum 22, labyrinth sealing groove 221, first thrust plate 23, second balancing assembly 3, adjustable gap 31, mounting seat 32, second thrust plate 33, transmission shaft 41, and shaft sleeve 42. DETAILED DESCRIPTION

[0037] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the specific implementation methods of the present application will be described below with reference to the accompanying drawings. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0038] In order to simplify the drawings, only the parts related to the application are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "one" not only means "only one", but also means "more than one".

[0039] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0040] In this document, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0042] In addition, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0043] The principle of a multistage centrifugal pump is based on the Navier-Stokes equation (NS equation) in fluid mechanics. It allows the liquid to be continuously accelerated and pressurized as it passes through the pump by setting up multiple impellers and guide vanes (also called guide vanes or baffles) inside the pump casing. When the motor drives the pump shaft to rotate, the impeller rotates with it, converting mechanical energy into kinetic energy and potential energy of the liquid. After the liquid enters the first-stage impeller, it is accelerated and part of its kinetic energy is converted into pressure energy, and then flows into the guide vane, which redistributes the kinetic energy of the liquid, reduces eddy current losses, and guides the liquid to the next-stage impeller. This process is repeated between each stage of the impeller and the guide vane. The pressure of the liquid increases once each stage passes, and finally a high-lift delivery is achieved. The design of the multistage centrifugal pump enables each stage to effectively increase the energy of the liquid, which makes the multistage centrifugal pump very useful in situations where high lift is required.

[0044] In a multi-stage centrifugal pump, when the liquid flows through the impeller, an axial force pointing to the low-pressure area is generated due to the different pressures before and after the impeller. The axial force elimination effect of the existing multi-stage centrifugal pump axial force elimination mechanism is poor, and there is still a lot of axial force that cannot be eliminated. In addition, the design structure is complex, resulting in excessive size.

[0045] In this regard, the present invention provides an axial force balancing mechanism for a multi-stage centrifugal pump, which can improve the axial force balancing effect while reducing the adverse effects of the balancing mechanism on the size of the multi-stage centrifugal pump, thereby meeting the demand for miniaturization of the multi-stage centrifugal pump.

[0046] For details, see the appendix of the manual. Figures 1 to 4A multi-stage centrifugal pump axial force balancing mechanism includes a pump shaft assembly, a bearing seat 1, a first balancing assembly 2 and a second balancing assembly 3, wherein one end of the pump shaft assembly is equipped with a final-stage impeller, and a bearing seat 1 is provided on the outside of the pump shaft assembly. The pump shaft assembly can rotate relative to the bearing seat 1 to drive the final-stage impeller to rotate, and a stopper is provided between the pump shaft assembly and the bearing seat 1. Correspondingly, a first balancing assembly 2 is provided on the outer fixed sleeve of the pump shaft assembly, and the first balancing assembly 2 is located inside the bearing seat 1, and a decompression channel is formed between its outer wall and the inner wall of the bearing seat 1. In addition, the first balancing assembly 2 is arranged on the side of the stopper close to the final-stage impeller, and a gap is provided between the stopper to form an adjustable balancing chamber 21 between the first balancing assembly 2 and the stopper, and the adjustable balancing chamber 21 is connected to the decompression channel and the inlet of the pump.

[0047] In addition, a second balancing assembly 3 is sleeved and fixed on the other end of the pump shaft assembly away from the final impeller. The second balancing assembly 3 is located outside the bearing seat 1 and is spaced apart from the stopper to form an adjustable gap 31 between the second balancing assembly 3 and the stopper.

[0048] In addition, one end of the pump shaft assembly passes through the bearing seat 1, and the pump shaft assembly can move along the extension direction of the bearing seat 1 as needed, so as to adjust the size of the adjustable balance chamber 21 and the adjustable gap 31 to achieve the balance control of the pump. Generally speaking, the pump shaft assembly will move relative to the extension direction of the bearing seat 1 under the action of axial force and pressure difference during operation.

[0049] The specific principle of balancing the axial force in actual use is as follows: the high-pressure fluid enters the adjustable balancing chamber 21 through the decompression channel, and the decompression channel can achieve the decompression effect on the high-pressure fluid, so that a pressure difference is formed at both ends of the first balancing component 2 (the pressure on the side of the first balancing component 2 away from the final impeller is higher than the pressure on the side away from the final impeller), thereby generating an upward force through the pressure difference to achieve the purpose of eliminating part of the axial force. See the attached figure of the specification Figure 1 When the multistage centrifugal pump works at rated conditions or at a lower head condition, the first balancing component 2 and the second balancing component 3 jointly bear the axial force under such conditions. When the multistage centrifugal pump works at rated conditions or at a lower head condition, the pressure difference of the first balancing component 2 is smaller than the magnitude of the axial force, so that the axial force drives the pump shaft component to move downward to reduce the adjustable gap 31 and increase the adjustable balancing chamber 21 until the second balancing component 3 is completely in contact with and squeezed with the end of the stopper away from the last-stage impeller. At this time, the stopper can provide an upward supporting force to the second balancing component 3, that is, provide an upward supporting force to the pump shaft component, thereby further balancing the axial force (that is, balancing the part of the axial force that is not balanced by the first balancing component 2).

[0050] When the multistage centrifugal pump is working at a high head, the pressure difference of the first balancing component 2 is greater than the axial force, so that the pressure difference drives the pump shaft component to move upward to increase the adjustable gap 31 and reduce the adjustable balancing chamber 21, until the first balancing component 2 is completely in contact with the end of the stopper away from the last-stage impeller, and the stopper can provide a downward supporting force to the first balancing component 2, that is, a downward supporting force to the pump shaft component, thereby achieving axial force balance. Under this condition, the stopper will not support the first balancing component 2, so under this condition, the balance of the axial force is completely borne by the first balancing component 2.

[0051] Compared with the axial force elimination method of the prior art, the axial force balancing mechanism of a multistage centrifugal pump provided in this embodiment can eliminate part of the axial force through the pressure difference, and can further eliminate the remaining axial force through the stopper and the first balancing component 2 or the second balancing component 3, and can well balance the axial force under both low head and high head conditions. Moreover, this embodiment has a simple structure, requires fewer components, and can significantly reduce the space occupied by the axial force balancing mechanism, thereby reducing the volume of the multistage centrifugal pump.

[0052] In one embodiment, see the attached specification Figure 1 This embodiment further describes the pump shaft assembly. The pump shaft assembly includes a transmission shaft 41 and a sleeve 42. The sleeve 42 is sleeved and fixed on the outside of the transmission shaft 41 and is arranged corresponding to the stopper. A final stage impeller is arranged at one end of the transmission shaft 41. Both ends of the sleeve 42 in the extension direction are respectively connected to the sides of the first balancing assembly 2 and the second balancing assembly 3 that are close to each other.

[0053] Furthermore, the stopper is sleeved on the outside of the pump shaft assembly, that is, sleeved on the outside of the pump shaft 41 , and is fixedly mounted on the inner wall of the bearing seat 1 .

[0054] It can be understood that the arrangement of the shaft sleeve 42 and the stopper can provide radial support for the transmission shaft 41 at the same time, ensuring that the pump shaft has good coaxiality during operation and providing higher stability and support for the high-speed rotating rotor.

[0055] For further information, see the appendix to the manual. Figure 2 The first balancing assembly 2 is composed of a balancing drum 22 and a first thrust plate 23, wherein the balancing drum 22 is fixedly sleeved on the outside of the shaft sleeve 42. An installation groove matching the first thrust plate 23 is provided at one end of the balancing drum 22 away from the final impeller, and the installation groove is used to fix the first thrust plate 23 on the balancing drum 22. The first thrust plate 23 and the stopper are arranged correspondingly to each other, and an adjustable balancing chamber 21 is formed therebetween.

[0056] The second balancing assembly 3 is composed of a mounting seat 32 and a second thrust plate 33, wherein the mounting seat 32 is fixed to the outside of the end of the pump shaft assembly away from the final impeller. An inner groove adapted to the second thrust plate 33 is provided on the side of the mounting seat 32 close to the stopper, and the inner groove is used to firmly mount the second thrust plate 33 in the mounting seat 32. In addition, the second thrust plate 33 is arranged opposite to the stopper to form an adjustable gap 31 therebetween.

[0057] It is understood that, see the attached manual Figure 1 The mounting groove is provided in the middle of the balancing drum 22 so that the inner ring of the balancing drum 22 is connected to one end of the sleeve 42, and the first thrust plate 23 provided in the mounting groove is provided correspondingly to the stopper. Accordingly, the inner groove is provided in the middle of the mounting seat 32 so that the inner ring of the mounting seat 32 is connected to the other end of the sleeve 42, and the second thrust plate 33 provided in the inner groove is provided correspondingly to the stopper. Therefore, when the transmission shaft 41 moves, the transmission shaft 41, the sleeve 42, the first balancing assembly 2 and the second balancing assembly 3 move synchronously relative to the stopper.

[0058] There are many ways to connect the sleeve 42, the balance drum 22 and the mounting seat 32 to the transmission shaft 41. Generally, they can be connected and fixed by a flat key. All of the above are within the scope of protection of the present invention.

[0059] In one embodiment, see the attached specification Figure 1 and Figure 4 This embodiment provides a specific structure of a stopper. A first guide groove 13 is provided at one end of the stopper close to the second balancing component 3, and the first guide groove 13 is provided at the end of the stopper. When the axial force balancing mechanism is working, the fluid can enter between the second balancing component 3 and the stopper through the first guide groove 13 under the action of the centrifugal pump, thereby forming a liquid film between the second thrust plate 33 and the stopper, thereby reducing friction, reducing wear, and extending the service life of the components. In addition, the liquid film can absorb and take away the heat generated by friction to prevent overheating.

[0060] In addition, preferably, a first guide groove 13 is also provided at one end of the stopper close to the last-stage impeller to form a liquid film between the stopper and the first balancing assembly 2. Accordingly, a second guide groove 14 connected to the first guide groove 13 is provided on the inner side wall of the stopper, and the second guide groove 14 can introduce liquid between the stopper and the shaft sleeve 42 for lubrication and cooling between the bearing and the shaft sleeve 42 to prevent dry friction.

[0061] Furthermore, the present embodiment further describes the stopper. The stopper includes a first bearing 11 and a second bearing 12, and the first bearing 11 and the second bearing 12 are sequentially arranged in a direction close to the final impeller. Accordingly, the first guide groove 13 is provided at one end of the first bearing 11 and the second bearing 12 that are away from each other. In addition, the inner walls of the first bearing 11 and the second bearing 12 are both provided with a second guide groove 14, which is connected to the first guide groove 13 on the corresponding bearing.

[0062] Preferably, the second guide groove 14 of the first bearing 11 is also connected to the second guide groove 14 of the second bearing 12 to allow the liquid to flow in the balancing mechanism.

[0063] In addition, the first thrust plate 23, the second thrust plate 33 and the stopper are made of the same material, that is, hard wear-resistant alloy, to ensure the service life of the balancing mechanism.

[0064] The size of the adjustable gap 31 is set to 0.5 mm-1 mm, which greatly reduces the axial size of the balance chamber, thereby making the axial size of the device more compact.

[0065] In one embodiment, see the attached specification Figure 2 A labyrinth-shaped sealing groove 221 is provided on the outer side wall of the balance drum 22, and the labyrinth-shaped sealing groove 221 is extended along the circumference of the balance drum 22 and along the length direction of the balance drum 22 to form a decompression channel between the balance drum 22 and the bearing seat 1. Preferably, the labyrinth-shaped sealing groove can be set as a toothed groove to further enhance the decompression effect of the decompression channel.

[0066] In one embodiment, this embodiment provides a multistage centrifugal pump, including a multistage centrifugal pump axial force balancing mechanism described in any of the above embodiments. The multistage centrifugal pump provided in this embodiment can effectively balance the axial force through the cooperation of the first balancing component 2, the second balancing component 3 and the stopper, reduce the axial movement of the pump shaft component, improve the operating stability of the pump, and reduce the wear between the second balancing component 3 and the stopper, thereby extending the service life of the second balancing component 3. In addition, balancing the axial force can also reduce faults such as broken shafts caused by unbalanced axial force, thereby improving the stability and reliability of the multistage pump.

[0067] It should be noted that the above embodiments can be freely combined as needed. The above are only preferred implementations of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application, and these improvements and modifications should also be regarded as the protection scope of the present application.

Claims

1. A multi-stage centrifugal pump axial force balancing mechanism, characterized in that: include: A pump shaft assembly, one end of which is provided with a final-stage impeller; A bearing seat, wherein the bearing seat is movably sleeved on the outside of the pump shaft assembly so that the pump shaft assembly can rotate relative to the bearing seat, and a stopper is provided between the bearing seat and the pump shaft assembly; A first balancing component, wherein the first balancing component is sleeved and fixed on the outside of the pump shaft component and is arranged inside the bearing seat, a decompression channel is arranged between the outer side wall of the first balancing component and the inner side wall of the bearing seat, the first balancing component is arranged on a side of the stopper close to the final-stage impeller, and an adjustable balancing chamber is formed between the stopper and the first balancing component, and the adjustable balancing chamber is communicated with both the decompression channel and the pump inlet of the bearing seat; A second balancing component, wherein the second balancing component is sleeved and fixed on an end of the pump shaft component away from the final-stage impeller and is located on the outer side of the bearing seat, and an adjustable gap is formed between the second balancing component and the stopper; Wherein, the pump shaft assembly is suitable for moving along the extension direction of the bearing seat to adjust the size of the adjustable balance chamber and the adjustable gap.

2. The axial force balancing mechanism of a multi-stage centrifugal pump according to claim 1, characterized in that: The stopper is sleeved on the outer side of the pump shaft assembly and is connected and fixed to the inner side wall of the bearing seat; A first guide groove is arranged at the end of the stopper, and a second guide groove connected with the first guide groove is arranged on the inner wall of the stopper. The first guide groove is used for liquid to flow in to form a liquid film between the second balancing component and the stopper.

3. The axial force balancing mechanism of a multi-stage centrifugal pump according to claim 2, characterized in that: The first balancing assembly comprises a balancing drum and a first thrust plate, wherein the balancing drum is sleeved and fixed on the outer side of the pump shaft assembly; A mounting groove matched with the first thrust plate is arranged on one side of the balance drum away from the last-stage impeller to fix the first thrust plate on the balance drum. The first thrust plate and the stopper are arranged correspondingly to form the adjustable balance chamber.

4. The axial force balancing mechanism of a multi-stage centrifugal pump according to claim 3, characterized in that: The second balancing assembly comprises a mounting seat and a second thrust plate, wherein the mounting seat is sleeved and fixed on the outer side of an end of the pump shaft assembly away from the final stage impeller; An inner groove matching with the second thrust disk is arranged on one side of the mounting seat close to the stopper to fix the second thrust disk on the mounting seat. The second thrust disk and the stopper are arranged correspondingly to form the adjustable gap.

5. The axial force balancing mechanism of a multi-stage centrifugal pump according to claim 4, characterized in that: The pump shaft assembly comprises a transmission shaft and a shaft sleeve, wherein the shaft sleeve is sleeved and fixed on the outer side of the transmission shaft and is arranged corresponding to the stopper; The sides of the balance drum and the mounting seat that are close to each other are respectively connected to the two ends of the shaft sleeve in the extending direction.

6. A multi-stage centrifugal pump axial force balancing mechanism according to any one of claims 3 to 5, characterized in that: A labyrinth-shaped sealing groove is arranged on the outer side wall of the balance drum to form the decompression channel.

7. The axial force balancing mechanism of a multi-stage centrifugal pump according to claim 6, characterized in that: The stopper includes a first bearing and a second bearing in sequence in a direction close to the last-stage impeller, and the first bearing and the second bearing are both provided with the first guide groove at ends away from each other; The second guide groove is arranged on the inner wall of the first bearing and the second bearing, and is communicated with the corresponding first guide groove.

8. The axial force balancing mechanism of a multi-stage centrifugal pump according to claim 5, characterized in that: The first thrust plate, the second thrust plate and the stopper are made of the same material.

9. The axial force balancing mechanism of a multi-stage centrifugal pump according to any one of claims 1 to 5, characterized in that: The size of the adjustable gap is 0.5mm-1mm.

10. A multistage centrifugal pump, characterized in that: It comprises an axial force balancing mechanism for a multi-stage centrifugal pump as described in any one of claims 1-9.

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