Horizontal multi-stage pump

Abstract

The utility model relates to a horizontal multi-stage pump, which solves the problems that a connecting frame and a pump cover seat are of an integrated structure, the size is large, the weight is heavy, more raw materials are consumed, a sealing assembly is difficult to assemble and the like in the prior art, and adopts the technical scheme that the horizontal multi-stage pump comprises a motor and a pump body which are connected through the connecting frame, and a multi-stage impeller string arranged in the pump body, the pump cover is arranged at the inner end of the pump body, the mechanical seal is arranged on the rotating shaft, the mechanical seal is matched with the pump cover, a pump cover seat is arranged on the rotating shaft, the pump cover seat is limited between the pump cover and the connecting frame, and the inner side of the pump cover seat is matched with the pump cover and used for limiting axial and radial displacement of a static ring of the mechanical seal. The mechanical seal has the advantages that the connecting frame and the pump cover seat are of a split structure, the size and weight are greatly reduced, raw material consumption is reduced, the heat dissipation cavity is formed between the connecting frame and the pump cover seat, heat dissipation of the static ring on the mechanical seal is facilitated, the sealing assembly is convenient to assemble, and the assembling efficiency and the sealing reliability are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to water pump field especially relates to a horizontal multistage pump. BACKGROUND

[0002] At present, horizontal multistage pump is widely used in water supply, water treatment, system pressure boosting, heating and ventilation and other system fields, but due to the high pressure in the pump, the rigidity of part structure is insufficient, and the product designed according to the problem itself has other design problems, which affects the user's pump experience, and even affects the normal and safe operation of the whole application system.

[0003] For example, the patent name is multistage centrifugal pump set (its announcement number is CN101832272B), and the technical scheme disclosed is as follows: Figure 4 As shown in the figure, the motor and the pump body are connected through the bearing support 13, the pump body and the bearing support 13 are provided with the inner lining part (equivalent to the pump cover 9 involved in this paper) 28 of stainless steel, the inner lining part 28 is provided with the outward flange ring (equivalent to the inner ring cylinder part involved in this paper) 1 extending axially towards the motor direction corresponding to the rotating shaft 3 (motor shaft or pump shaft), the outer end of the outward flange ring is in a free end state, and the outward flange ring of the inner lining part 28 is matched with the mechanical seal 2 arranged on the rotating shaft.

[0004] For the outward flange ring, when the multistage centrifugal pump set works, the mechanical seal is easy to deform the outer end of the outward flange ring 1 on the inner lining part 28, which leads to the failure of sealing effect, and further affects the normal working efficiency of the pump.

[0005] In addition, the outer end (i.e. the end away from the pump body) of the bearing support 13 is provided with a bearing assembly cavity (a bearing 4 is arranged in the bearing assembly cavity) and an axial sealing cavity (i.e. the axial sealing assembly is closer to the pump body relative to the bearing assembly cavity) arranged on the inner side of the bearing assembly cavity, the axial sealing cavity is provided with a sealing assembly 5, and during assembly, the bearing 4 and the sealing assembly 5 are assembled to the rotating shaft and move axially with the rotating shaft, and the bearing and the axial sealing assembly are assembled into the bearing assembly cavity and the axial sealing cavity respectively. Since the axial sealing cavity is located on the inner side of the bearing assembly cavity and has a small size, it is difficult to determine whether the axial sealing assembly is assembled in place, not only the assembly is complicated, but also the assembly is easy to be out of place and lead to leakage, which causes the leakage into the motor and causes the failure problem. Moreover, the bearing support 13 has sufficient radial length to set the bearing assembly cavity and the axial sealing cavity with sufficient depth, at the same time, the outer diameter of the bearing support 13 is adapted to the outer diameter of the corresponding parts of the pump body and the motor, which is used to connect the pump body and the motor, so that the bearing support 13 has large volume and large weight, and consumes a large amount of raw materials. SUMMARY

[0006] The utility model discloses a horizontal multistage pump which adopts a split structure of the connecting frame and the pump cover seat, can greatly reduce the volume of the pump cover seat, reduce the weight of the pump cover seat and reduce the raw material consumption, and can form a heat dissipation cavity between the connecting frame and the pump cover seat, which is beneficial to the heat dissipation of the static ring on the mechanical seal, thereby improving the use reliability and service life of the mechanical seal.

[0007] The utility model discloses a horizontal multistage pump which adopts a split structure of the connecting frame and the pump cover seat, can greatly reduce the volume of the pump cover seat, reduce the weight of the pump cover seat and reduce the raw material consumption, and can form a heat dissipation cavity between the connecting frame and the pump cover seat, which is beneficial to the heat dissipation of the static ring on the mechanical seal, thereby improving the use reliability and service life of the mechanical seal.

[0008] As a further improvement and supplement to the above technical solution, the utility model adopts the following technical measures:

[0009] As a preferred embodiment, the rotating shaft is provided with a sealing assembly, and a sealing cavity is formed between the outer side of the pump cover seat and the inner side of the connecting frame. The sealing assembly is arranged in the sealing cavity and is used to prevent the leakage of liquid into the interior of the motor in the axial direction. Since the connecting frame and the pump cover seat are of a split structure, the sealing assembly can be assembled separately in an open space. After assembly, the connecting frame and the pump cover seat are assembled, which greatly facilitates the assembly of the sealing assembly and greatly improves the assembly efficiency. At the same time, the sealing reliability of the sealing assembly is greatly improved, thereby improving the use reliability and service life of the motor. The arrangement of the sealing assembly is beneficial to preventing the leakage of liquid from the pump body along the rotating shaft to the sealing cavity on the outside and into the interior of the motor, thereby ensuring the use reliability of the motor.

[0010] As preferred, the sealing assembly comprises a water baffle ring and a skeleton seal, both of which are matched with the rotating shaft, the rotating shaft is provided with an assembly groove, the water baffle ring is axially positioned and matched with the assembly groove, the inner end (i.e. the end towards the pump body) of the connecting frame is provided with a sealing ring groove, and the skeleton seal is embedded in the sealing ring groove. During assembly, the sealing skeleton seal is embedded in the sealing ring groove, the pump cover seat is placed on the rotating shaft, and then the water baffle ring is embedded in the assembly groove, and finally the connecting frame is matched with the rotating shaft, the pump body, the pump cover and the pump cover seat. Therefore, when assembling the water baffle ring and the skeleton seal, there is enough operating space around, and there is no other interference, which is convenient and efficient to operate, and can also ensure the assembly position reliability, thereby improving the reliability and service life of the motor.

[0011] As preferred, the outer diameter of the pump cover seat is smaller than the inner diameter of the connecting frame, and the pump cover seat and the connecting frame have a heat dissipation cavity. The connecting frame is a shell structure, the outer side of which is connected with the motor, the inner side of which has a larger inner cavity in the middle region, and the inner end of the outer periphery of the inner side is connected with the pump body. The pump cover seat is arranged in the inner cavity of the connecting frame, the outer diameter of the pump cover seat is smaller than the inner diameter of the connecting frame, and the thickness of the pump cover seat is also smaller than the depth of the inner cavity of the connecting frame, so that the volume of the pump cover seat is relatively small. After the combination of the pump cover seat and the connecting frame, there is also a heat dissipation cavity between them. Compared with the bearing support of the prior art, the weight and raw materials consumed corresponding to the heat dissipation cavity can be saved. Therefore, the improved technical solution is convenient for assembling the sealing assembly, which is conducive to reducing the volume and raw material consumption, and also conducive to forming a heat dissipation cavity to provide a heat dissipation effect for the static ring, thereby improving the sealing performance and service life of the mechanical seal.

[0012] As preferred, the pump cover seat and / or the connecting frame are provided with a drainage hole, the drainage hole communicates the sealing cavity and the heat dissipation cavity, the outer wall of the connecting frame is provided with a drainage channel, and the heat dissipation cavity communicates the drainage channel with the external space. The liquid in the pump body can penetrate along the rotating shaft to the leakage in the sealing cavity, and then be discharged through the drainage hole, which is conducive to preventing the leakage from entering the motor, thereby ensuring the reliability of the motor.

[0013] As preferred, the middle part of the pump cover is provided with an axial assembly through hole, the inner ring wall of the pump cover is provided with an axially outwardly folded inner ring cylinder part, the outer ring wall of the static ring of the mechanical seal is in abutting fit with the inner ring wall of the inner ring cylinder part, the outer end face of the static ring is in abutting fit with the inner end wall of the pump cover seat, and a sealing ring is arranged between the static ring and the inner ring cylinder part and / or the pump cover seat. The inner cavity of the inner ring cylinder part forms an assembly cavity of the static ring, and the static ring is radially limited. The outer end face of the static ring is abutted by the inner end wall of the pump cover seat, and the two ends of the static ring are axially limited by the pump cover seat and the dynamic ring assembly of the mechanical seal respectively. The sealing ring is used for sealing the gap between the static ring and the inner ring cylinder part and the pump cover seat, reducing the leakage of the liquid in the pump body through the gap, being beneficial to ensuring the hydraulic efficiency of the pump, and being beneficial to reducing the possibility of the leaked liquid entering the motor along the rotating shaft, thereby being beneficial to ensuring the use reliability of the motor.

[0014] In addition, in the technical solution, the inner ring cylinder part corresponds to the outwardly folded ring in the prior art, the outer end of the inner ring cylinder part is a free end, and because the two side walls of the inner ring cylinder part are in abutting fit with the static ring and the pump cover seat respectively, the inner ring cylinder part is completely limited in the gap between the static ring and the pump cover seat, which is beneficial to improving the deformation resistance of the inner ring cylinder part and avoiding deformation caused by external force, thereby being beneficial to ensuring the sealing reliability of the mechanical seal.

[0015] As preferred, the outer end of the static ring is provided with a convex ring, the outer end of the static ring is provided with a first stop, the inner end wall of the pump cover seat is provided with a stepped concave ring recessed towards the outer end direction, the convex ring is inserted into the stepped concave ring, and an axial and radial stop fit is formed between the stepped concave ring and the first stop. It is beneficial to further limit the axial and radial displacement of the static ring, stabilize the position of the static ring, and improve the sealing effect of the static ring.

[0016] As preferred, the outer end of the pump cover seat is provided with a second stop recessed towards the inner end direction, the inner end of the connecting frame is provided with an insertion ring protruding towards the inner side direction, the insertion ring is inserted into the second stop, and the connecting frame is used for limiting the axial and radial displacement of the outer end of the pump cover seat. It is beneficial to improve the assembly stability between the pump cover seat and the connecting frame, thereby being beneficial to the sealing reliability of the sealing assembly arranged between the pump cover seat and the connecting frame.

[0017] As preferred, the outer edge of the connecting frame is provided with a cylinder part extending towards the inner side direction, the end of the cylinder part is provided with an insertion slot recessed towards the outer end direction, the outer edge of the pump cover is provided with an axially outwardly folded outer ring cylinder part, and the outer ring cylinder part and the outer end of the pump body are inserted into the insertion slot to form a connection. It is beneficial to improve the connection reliability between the connecting frame and the pump cover and the pump body.

[0018] Preferably, the inner end of the cylindrical portion has a first pressing ring surface, the pump cover is provided with a second pressing ring surface and a third pressing ring surface, and the pump cover seat is provided with a fourth pressing ring surface, the first pressing ring surface and the second pressing ring surface form a surface contact pressing fit, and the third pressing ring surface and the fourth pressing ring surface form a surface contact pressing fit. The pump cover, the pump cover seat and the connecting frame form a surface contact pressing fit, which is beneficial to improve the assembly reliability of the pump cover, the pump cover seat and the connecting frame.

[0019] The utility model discloses have beneficial effect: 1, adopt the connecting frame and pump cover seat of split structure, can reduce the volume of pump cover seat greatly, reduce the weight of pump cover seat and reduce raw material consumption, and can form the heat dissipation cavity between connecting frame and pump cover seat, be favorable to the static ring heat dissipation on mechanical seal, thereby be favorable to improve the use reliability and service life of mechanical seal. 2, because the two side walls of inner ring cylinder portion form the pressing fit with static ring and pump cover seat respectively, make inner ring cylinder portion completely limit in the clearance between static ring and pump cover seat, be favorable to improve the deformation resistance of inner ring cylinder portion, avoid the deformation condition under the action of external force, thereby be favorable to ensure the sealing reliability of mechanical seal. 3, connecting frame and pump cover seat are split structure, not only convenient sealing assembly, improve the assembly efficiency, and also be favorable to improve the accuracy of sealing assembly assembly position, ensure the sealing effect of sealing assembly, further be favorable to ensure the motor use reliability. 4, the setting of drain hole, be favorable to make the liquid in the pump body along the shaft to the liquid leakage in the sealing cavity through drain hole and discharge, be favorable to prevent the possible liquid leakage into the motor, further be favorable to ensure the motor use reliability. 4, the heat dissipation cavity is formed between pump cover seat and connecting frame, be favorable to improve the heat dissipation effect of static ring, thereby be favorable to improve the sealing performance and service life of mechanical seal. 5, the setting of drainage channel, not only be favorable to the liquid leakage in the heat dissipation cavity and timely discharge to the external space, avoid the accumulation and the liquid leakage to the inside of motor, be favorable to further ensure the motor operation reliability, also be favorable to the heat of static ring through the discharge of liquid leakage and be transferred to liquid leakage, further be favorable to improve the heat dissipation effect of static ring. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a partial sectional structure schematic view of the utility model.

[0021] Figure 2 It is Figure 1 The partial structure amplification schematic view of.

[0022] Figure 3 It is Figure 2 The amplification structure schematic view of A part in.

[0023] Figure 4 It is a structure schematic view of prior art.

[0024] Fig. 1, 1, the outer ring; 2, mechanical seal; 3, rotating shaft; 4, bearing; 5, sealing assembly; 7, motor; 8, pump body; 9, pump cover; 10, pump cover seat; 11, connecting frame; 12, static ring; 13, sealing cavity; 14, water baffle ring; 15, skeleton seal; 16, heat dissipation cavity; 17, drain hole; 18, drainage channel; 19, inner ring cylinder part; 20, sealing ring; 21, first stop; 22, convex ring; 23, bearing support; 24, second stop; 25, cylindrical part; 26, plug-in slot; 27, outer ring cylinder part; 28, first pressing ring surface; 29, second pressing ring surface; 30, third pressing ring surface; 31, fourth pressing ring surface. DETAILED DESCRIPTION

[0025] The technical scheme of the utility model is further specifically explained below by examples and in conjunction with the drawings. In the technical scheme, the direction towards the motor is the "outer" direction, and the direction towards the pump body is the "inner" direction.

[0026] Embodiment: As shown in the figure, a horizontal multi-stage pump comprises a motor 7 and a pump body 8 connected by a connecting frame 11, a multi-stage impeller string arranged in the pump body 8, a pump cover 9 arranged at the inner end of the pump body 8, and a mechanical seal 2 arranged on the rotating shaft 3, wherein the mechanical seal 2 cooperates with the pump cover 9. Figures 1-3

[0027] The difference between the technical scheme and the prior art is that the pump cover seat 10 is arranged on the rotating shaft 3, the pump cover seat 10 is limited between the pump cover 9 and the connecting frame 11, the inner side of the pump cover seat 10 cooperates with the pump cover 9, and is used for limiting the axial and radial displacement of the static ring 12 of the mechanical seal 2.

[0028] The difference between the technical scheme and the prior art is that the connecting frame 11 and the pump cover seat 10 of the split structure replace the bearing 4 support in the prior art. The connecting frame 11 and the pump cover seat 10 of the split structure can greatly reduce the volume of the pump cover seat 10, reduce the weight of the pump cover seat 10 and reduce the consumption of raw materials, and can form a heat dissipation cavity 16 between the connecting frame 11 and the pump cover seat 10, which is beneficial to the heat dissipation of the static ring 12 on the mechanical seal 2, thereby improving the use reliability and service life of the mechanical seal 2.

[0029] In the technical scheme, the outer end of the connecting frame 11 is provided with a bearing 4 chamber for arranging the bearing 4. The inner end middle area of the connecting frame 11 cooperates with the pump cover seat 10 to arrange a sealing cavity 13 for arranging a sealing assembly 5.

[0030] The above technical scheme is further explained as follows:

[0031] ​In actual application, the shaft 3 is provided with a sealing assembly 5, a sealing cavity 13 is formed between the outer side of the pump cover base 10 and the inner side of the connecting frame 11, and the sealing assembly 5 is arranged in the sealing cavity 13, so that the sealing assembly 5 can prevent liquid leakage from entering the inside of the motor 7 in the axial direction.

[0032] In the technical solution, the connecting frame 11 and the pump cover base 10 are in a split structure, so that the sealing assembly 5 can be assembled in an open space, and then the connecting frame 11 and the pump cover base 10 are assembled after the assembly is completed, which can greatly facilitate the assembly of the sealing assembly 5, greatly improve the assembly efficiency, and greatly improve the sealing reliability of the sealing assembly 5, thereby improving the use reliability and service life of the motor 7. The sealing assembly 5 can prevent liquid in the pump body 8 from penetrating into the sealing cavity 13 along the shaft 3 to the outside, and then entering the inside of the motor 7, thereby ensuring the use reliability of the motor 7.

[0033] In actual application, the sealing assembly 5 includes a water baffle 14 and a skeleton seal 15 which are matched with the shaft 3, the shaft 3 is provided with an assembly groove, the water baffle 14 is axially positioned and matched with the assembly groove, and the inner end (i.e., the end facing the pump body 8) of the connecting frame 11 is provided with a sealing ring groove, and the skeleton seal 15 is embedded in the sealing ring groove.

[0034] In the technical solution, the skeleton seal 15 is embedded in the sealing ring groove, the pump cover base 10 is sleeved on the shaft 3, and then the water baffle 14 is embedded in the assembly groove, and finally the connecting frame 11 is matched with the shaft 3, the pump body 8, the pump cover 9 and the pump cover base 10.

[0035] Therefore, the technical solution has sufficient operation space around when assembling the water baffle 14 and the skeleton seal 15, and there is no other interference, which is convenient and efficient to operate, and can ensure the assembly position reliability, thereby improving the use reliability and service life of the motor 7.

[0036] In actual application, the outer diameter of the pump cover base 10 is smaller than the inner diameter of the connecting frame 11, and the pump cover base 10 and the connecting frame 11 have a heat dissipation cavity 16.

[0037] In the technical solution, the connecting frame 11 is a shell-shaped structure, the outer side of which is connected with the motor 7, the middle part of the inner side of which has a larger inner cavity, and the inner end of the periphery of the inner side forms a connection with the pump body 8. The pump cover seat 10 is arranged in the inner cavity of the connecting frame 11, the outer diameter of the pump cover seat 10 is smaller than the inner diameter of the connecting frame 11, and the thickness of the pump cover seat 10 is also smaller than the depth of the inner cavity of the connecting frame 11, so that the volume of the pump cover seat 10 is relatively small. After the combination of the pump cover seat 10 and the connecting frame 11, the heat dissipation cavity 16 is also formed between the two, compared with the bearing 4 support of the prior art, the weight and raw materials consumed corresponding to the volume of the heat dissipation cavity 16 can be saved. Therefore, the improved technical solution is convenient for assembling the sealing assembly 5, is conducive to reducing the volume and raw material consumption, is also conducive to forming the heat dissipation cavity 16, providing the heat dissipation effect of the static ring 12, thereby being conducive to improving the sealing performance and service life of the mechanical seal 2.

[0038] In actual application, the pump cover seat 10 can also be provided with heat dissipation fins or heat dissipation holes for increasing the heat dissipation area and enhancing the heat dissipation effect of the static ring 12 and improving the heat dissipation efficiency.

[0039] In actual application, the pump cover seat 10 and / or the connecting frame 11 are provided with a drainage hole 17, the drainage hole 17 communicates the sealing cavity 13 and the heat dissipation cavity 16, the outer wall of the connecting frame 11 is provided with a drainage channel 18, and the heat dissipation cavity 16 communicates the drainage channel 18 and the external space.

[0040] In the technical solution, the liquid in the pump body 8 can be permeated along the rotating shaft 3 to the sealing cavity 13 outside, and the leakage liquid can be discharged through the drainage hole 17, which is conducive to preventing the leakage liquid from entering the motor 7, thereby being conducive to ensuring the use reliability of the motor 7.

[0041] In actual application, the middle part of the pump cover 9 is provided with an axial assembly through hole, the inner ring wall of the pump cover 9 has an inner ring cylinder part 19 which is axially outwardly folded, the outer ring wall of the static ring 12 of the mechanical seal 2 is in abutting fit with the inner ring wall of the inner ring cylinder part 19, the outer end surface of the static ring 12 is in abutting fit with the inner end wall of the pump cover seat 10, and the sealing ring 20 is arranged between the static ring 12 and the inner ring cylinder part 19 and / or the pump cover seat 10.

[0042] In the technical solution, the inner cavity of the inner ring cylinder part 19 forms an assembly cavity of the static ring 12, and the static ring 12 is radially limited. The outer end surface of the static ring 12 is pressed against the inner end wall of the pump cover base 10, and the two ends of the static ring 12 are axially limited by the pump cover base 10 and the dynamic ring assembly of the mechanical seal 2 respectively. The sealing ring 20 is used to seal the gap between the static ring 12 and the inner ring cylinder part 19 and the pump cover base 10, so as to reduce the leakage of liquid in the pump body 8 through the gap, which is not only beneficial to ensure the hydraulic efficiency of the pump, but also beneficial to reduce the possibility of the leaked liquid entering the motor 7 along the rotating shaft 3, thereby being beneficial to ensure the use reliability of the motor 7.

[0043] In the technical solution, the inner ring cylinder part 19 corresponds to the existing technology of the outward turning ring 1, and the outer end of the inner ring cylinder part 19 is a free end. Since the two side walls of the inner ring cylinder part 19 are respectively in abutting fit with the static ring 12 and the pump cover base 10, the inner ring cylinder part 19 is completely limited in the gap between the static ring 12 and the pump cover base 10, so as to avoid deformation caused by external force, thereby being beneficial to ensure the sealing reliability of the mechanical seal 2.

[0044] In actual application, in order to further limit the axial and radial displacement of the static ring 12 and stabilize the position of the static ring 12, thereby being beneficial to improve the sealing effect of the static ring 12, the outer end of the static ring 12 is provided with a convex ring 22, the outer end of the static ring 12 has a first stop 21, the inner end wall of the pump cover base 10 is provided with a stepped concave ring recessed towards the outer end direction, the convex ring 22 is inserted into the stepped concave ring, and the stepped concave ring and the first stop 21 form an axial and radial stop displacement fit.

[0045] In actual application, in order to improve the assembly stability between the pump cover base 10 and the connecting frame 11, thereby being beneficial to the sealing reliability of the sealing assembly 5 arranged between the pump cover base 10 and the connecting frame 11, the outer end of the pump cover base 10 is provided with a second stop 24 recessed towards the inner end direction, the inner end of the connecting frame 11 has an insertion ring protruding towards the inner side direction, the insertion ring is inserted into the second stop 24, and the connecting frame 11 limits the axial and radial displacement of the outer end of the pump cover base 10.

[0046] In actual application, in order to improve the connection reliability between the connecting frame 11 and the pump cover 9 and the pump body 8, the outer edge of the connecting frame 11 has a cylindrical part 25 extending towards the inner side direction, the end of the cylindrical part 25 is provided with an insertion groove 26 recessed towards the outer end direction, the outer edge of the pump cover 9 has an outer ring cylinder part 27 outwardly turned in the axial direction, and the outer ring cylinder part 27 and the outer end of the pump body 8 are inserted into the insertion groove 26 to form a connection.

[0047] In actual application, the inner end of the cylindrical part 25 is provided with a first pressing ring surface 28, the pump cover 9 is provided with a second pressing ring surface 29 and a third pressing ring surface 30, and the pump cover base 10 is provided with a fourth pressing ring surface 31, the first pressing ring surface 28 and the second pressing ring surface 29 form a surface contact pressing fit, and the third pressing ring surface 30 and the fourth pressing ring surface 31 form a surface contact pressing fit.

[0048] In the technical solution, the pump cover 9, the pump cover base 10 and the connecting frame 11 form a surface contact pressing fit, which is beneficial to improve the assembly reliability of the pump cover 9, the pump cover base 10 and the connecting frame 11.

[0049] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. In the above embodiments, the present application can be variously changed and modified. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A horizontal multistage pump comprising a motor (7) and a pump body (8) connected by a connecting frame (11), a string of multistage impellers arranged inside the pump body (8), a pump cover (9) arranged at the inner end of the pump body (8), a mechanical seal (2) arranged on a rotating shaft (3), the mechanical seal (2) cooperating with the pump cover (9), characterized in that The rotating shaft (3) is provided with a pump cover seat (10), which is limited between the pump cover (9) and the connecting frame (11), the inner side of the pump cover seat (10) is matched with the pump cover (9) for limiting the axial and radial displacement of the static ring (12) of the mechanical seal (2).

2. The horizontal multi-stage pump according to claim 1, characterized in that The rotating shaft (3) is provided with a sealing assembly (5), the outer side of the pump cover seat (10) and the inner side of the connecting frame (11) have a sealing cavity (13), the sealing assembly (5) is arranged in the sealing cavity (13), and the sealing assembly (5) is used for preventing the axial leakage of liquid into the inside of the motor (7).

3. The horizontal multi-stage pump according to claim 2, characterized in that The sealing assembly (5) comprises a water baffle ring (14) and a skeleton seal (15) which are matched with the rotating shaft (3), the rotating shaft (3) is provided with an assembly groove, the water baffle ring (14) is axially positioned and matched with the assembly groove, and the inner end of the connecting frame (11) is provided with a sealing ring groove, and the skeleton seal (15) is embedded in the sealing ring groove.

4. The horizontal multi-stage pump according to claim 3, characterized in that The outer diameter of the pump cover seat (10) is smaller than the inner diameter of the connecting frame (11), and the pump cover seat (10) and the connecting frame (11) have a heat dissipation cavity (16).

5. The horizontal multi-stage pump according to claim 4, characterized in that The pump cover seat (10) and / or the connecting frame (11) are provided with a drain hole (17), the drain hole (17) communicates the sealing cavity (13) and the heat dissipation cavity (16), the outer wall of the connecting frame (11) is provided with a drain channel (18), and the heat dissipation cavity (16) communicates the drain channel (18) and an external space.

6. The horizontal multi-stage pump according to any one of claims 1 to 5, characterized in that The middle part of the pump cover (9) is provided with an axial assembly through hole, the inner ring wall of the pump cover (9) has an inner ring cylinder portion (19) which is folded outward in the axial direction, the outer ring wall of the static ring (12) is in abutting fit with the inner ring wall of the inner ring cylinder portion (19), the outer end surface of the static ring (12) is in abutting fit with the inner end wall of the pump cover seat (10), and a sealing ring (20) is arranged between the static ring (12) and the inner ring cylinder portion (19) and / or the pump cover seat (10).

7. The horizontal multi-stage pump according to claim 5, characterized in that The outer end of the static ring (12) is provided with a convex ring (22), the outer end of the static ring (12) has a first stop opening (21), the inner end wall of the pump cover seat (10) is provided with a stepped concave ring which is recessed towards the outer end direction, the convex ring (22) is inserted into the stepped concave ring, and the stepped concave ring and the first stop opening (21) are in axial and radial stop displacement fit.

8. The horizontal multi-stage pump according to claim 6, characterized in that The outer end of the pump cover seat (10) is provided with a second stop opening (24) which is recessed towards the inner end direction, the inner end of the connecting frame (11) has an insertion ring which is protruded towards the inner side direction, the insertion ring is inserted into the second stop opening (24), and the connecting frame (11) is used for limiting the axial and radial displacement of the outer end of the pump cover seat (10).

9. The horizontal multi-stage pump according to claim 8, characterized in that The outer edge of the connecting frame (11) has a cylindrical portion (25) extending towards the inner side, the end of the cylindrical portion (25) is provided with a plug-in slot (26) recessed towards the outer end, the outer edge of the pump cover (9) has an outer ring cylindrical portion (27) folded axially outwards, the outer ring cylindrical portion (27) and the outer end of the pump body (8) are inserted into the plug-in slot (26) to form the connection.

10. The horizontal multi-stage pump according to claim 9, characterized in that The inner end of the cylindrical portion (25) has a first pressing ring surface (28), the pump cover (9) is provided with a second pressing ring surface (29) and a third pressing ring surface (30), the pump cover seat (10) is provided with a fourth pressing ring surface (31), the first pressing ring surface (28) and the second pressing ring surface (29) form a surface contact pressing fit, and the third pressing ring surface (30) and the fourth pressing ring surface (31) form a surface contact pressing fit.

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