Mechanical sealing structure for axial flow pump and axial flow pump

Abstract

The utility model discloses a mechanical sealing structure for an axial flow pump and the axial flow pump, and relates to the technical field of axial flow pumps. The mechanical sealing device comprises a mechanical sealing shaft sleeve, a medium side sealing part, an atmosphere side sealing part and an inner sealing box body, the inner sealing box body is arranged among the medium side sealing part, the axial flow pump shell and the atmosphere side sealing part in a sealing manner; a protective sleeve is arranged at the end, close to the medium side sealing part, of the mechanical seal shaft sleeve, and a crushing notch capable of rotationally crushing crystals in a medium is formed in the side wall of the protective sleeve. The medium side sealing part comprises a medium side compensation ring arranged between the inner sealing box body and the mechanical sealing shaft sleeve; the atmosphere side sealing part comprises an atmosphere side gland which is arranged between the inner sealing box body and the mechanical sealing shaft sleeve and is detachably connected with the axial flow pump shell; an atmosphere side compensation ring is arranged between the inner side of the atmosphere side gland and the mechanical seal shaft sleeve; a first spacer fluid annulus is arranged between the medium side sealing part and the mechanical seal shaft sleeve and between the atmosphere side sealing part and the mechanical seal shaft sleeve, and a second spacer fluid annulus is arranged between the inner sealing box body and the medium side compensation ring.

Description

Technical Field

[0001] This utility model relates to the field of axial flow pump technology, and in particular to a mechanical seal structure for an axial flow pump and an axial flow pump. Background Technology

[0002] Axial flow pumps are pumps that use the force exerted by the blades of a rotating impeller on the liquid to transport it along the axial direction. They come in several types, including vertical, horizontal, inclined, and through-flow pumps, and typically have a large flow rate. In an axial flow pump, the pump shaft drives the impeller to rotate via a prime mover (such as an electric motor). The high-speed rotation of the impeller, based on the lift principle of airfoils, generates thrust on the liquid, thereby achieving liquid transport.

[0003] Because the rotating shaft (pump shaft) of an axial flow pump is a cantilever structure with relatively thick and heavy impellers, low rotational speed, and significant shaft vibration, the mechanical seal structure mounted on it is prone to failure. Some pumped media are prone to crystallization and contain particulate impurities and high chloride ion content; large crystal blocks can easily cause the end face of the mechanical seal structure to break. Furthermore, the large flow rate of the medium in an axial flow pump results in large crystals severely impacting the end face of the mechanical seal structure, causing fluctuations in the mechanical seal structure, leading to accelerated wear, and affecting the service life of the mechanical seal structure.

[0004] The existing conventional mechanical seal structure cannot completely isolate the impact of large crystals and the fluctuation of the pump shaft. The mechanical seal structure needs to be replaced frequently, resulting in cost waste. In addition, some pumps are particularly large, and the replacement process inevitably leads to the damage and replacement of other parts on the pump, which affects the operation of the entire device.

[0005] Therefore, a mechanical seal structure for axial flow pumps and an axial flow pump are proposed to overcome the shortcomings of existing technologies. Utility Model Content

[0006] The purpose of this invention is to provide a mechanical seal structure and an axial flow pump for axial flow pumps, overcoming the problem in the prior art where the mechanical seal structure is subject to fluctuations due to severe impact from crystallization, leading to increased wear and affecting the service life of the mechanical seal structure. In this invention, an effective seal is achieved through a cartridge-type mechanical seal structure composed of a medium-side sealing part, an atmospheric-side sealing part, and an inner sealing box. Furthermore, by setting a compensation ring and injecting pressurized isolation fluid, the damage caused by the impact fluctuations of crystallization is buffered, thereby improving the service life of the mechanical seal structure for axial flow pumps.

[0007] The purpose of this utility model is achieved as follows: a mechanical seal structure for an axial flow pump includes a mechanical seal bushing, a medium-side sealing part, an atmospheric-side sealing part, and an inner sealing housing; the inner sealing housing is sealed between the medium-side sealing part, the axial flow pump housing, and the atmospheric-side sealing part; a protective sleeve is provided at one end of the mechanical seal bushing near the medium-side sealing part, and the side wall of the protective sleeve is provided with a breaking notch that can rotate and break up crystals in the medium; the medium-side sealing part includes a component disposed between the inner sealing housing and the mechanical seal bushing, capable of axial sealing movement and radial floating to compensate for... The medium-side compensation ring for compensating for impact displacement includes an atmospheric-side sealing portion comprising an atmospheric-side pressure cap disposed between the inner sealing housing and the mechanical seal bushing and detachably connected to the axial flow pump housing; an atmospheric-side compensation ring capable of axial movement to compensate for impact displacement is disposed between the inner side of the atmospheric-side pressure cap and the mechanical seal bushing; a first isolation fluid annulus is disposed between the radially inner side of the medium-side sealing portion and the atmospheric-side sealing portion and the mechanical seal bushing; and a second isolation fluid annulus capable of communicating with the first isolation fluid annulus is disposed between the inner sealing housing and the medium-side compensation ring.

[0008] In a preferred embodiment of this utility model, the medium-side sealing portion includes a medium-side non-compensating ring, a medium-side compensating ring, and a first axial elastic compensating power unit disposed along the axial direction. The first end of the medium-side compensating ring and the medium-side non-compensating ring are exposed outside the inner sealing housing. The inner side of one end of the medium-side non-compensating ring, the radial inner side of the medium-side compensating ring and the first axial elastic compensating power unit are radially spaced from the mechanical seal bushing. The medium-side non-compensating ring seals and abuts against the mechanical seal bushing and the first end of the medium-side compensating ring. The first axial elastic compensating power unit axially abuts against the second end of the medium-side compensating ring to keep the first end of the medium-side compensating ring sealingly abutting against the medium-side non-compensating ring. The medium-side non-compensating ring and the mechanical seal bushing are circumferentially fixed relative to each other. The medium-side compensating ring and the inner sealing housing are circumferentially fixed relative to each other.

[0009] In a preferred embodiment of this utility model, a backflow sleeve is provided between the medium-side compensation ring and the mechanical seal bushing. The inner wall of the backflow sleeve and the mechanical seal bushing are radially spaced apart, and the outer wall of the backflow sleeve and the inner wall of the medium-side compensation ring are radially spaced apart. The end of the backflow sleeve near the medium-side non-compensation ring is open. The end of the backflow sleeve away from the medium-side non-compensation ring is fixed between the inner sealing box and the atmospheric pressure cover.

[0010] In a preferred embodiment of this utility model, the first axial elastic compensation power unit includes a first spring and a spring seat. The end of the spring seat away from the non-compensation ring on the medium side is provided with a first spring connecting groove. The two ends of the first spring are respectively abutted and connected to the bottom of the first spring connecting groove and the end of the backflow sleeve away from the non-compensation ring on the medium side. The end of the spring seat near the non-compensation ring on the medium side is connected to the second end of the compensation ring on the medium side. The end of the spring seat away from the non-compensation ring on the medium side is axially spaced from the backflow sleeve. The side wall of the spring seat away from the mechanical seal sleeve is radially spaced from the inner wall of the inner sealing box.

[0011] In a preferred embodiment of the present invention, a first anti-rotation pin is provided between the medium-side non-compensating ring and the mechanical seal bushing; a first shoulder is provided on the medium-side non-compensating ring, the first shoulder abuts axially against the end head of the mechanical seal bushing, and a bushing medium-side sealing part is provided between the inner wall of the medium-side non-compensating ring and the outer wall of the end head of the mechanical seal bushing.

[0012] In a preferred embodiment of this utility model, a floating second anti-rotation pin is provided between the inner sealing box and the medium-side compensation ring; an inner box medium-side sealing part is provided between the inner wall of the inner sealing box and the medium-side compensation ring on the side of the second anti-rotation pin near the medium-side non-compensation ring; an inner box housing sealing part is provided between the outer wall of the inner sealing box and the inner wall of the axial flow pump housing, and an inner box housing sealing part is provided between the end outer wall of the inner sealing box and the axial flow pump housing; an inner box atmospheric-side sealing part is provided between the inner sealing box and the atmospheric-side pressure cover.

[0013] In a preferred embodiment of this utility model, the atmospheric side sealing part includes an atmospheric side non-compensating ring, an atmospheric side compensating ring, and a second axial elastic compensating power part. The atmospheric side non-compensating ring axially abuts against the atmospheric side pressure cap and the atmospheric side compensating ring. The second axial elastic compensating power part axially abuts against the second end of the atmospheric side compensating ring so that the first end of the atmospheric side compensating ring remains sealed against the atmospheric side non-compensating ring. The atmospheric side non-compensating ring and the atmospheric side pressure cap are circumferentially fixedly arranged relative to each other. The atmospheric side compensating ring and the mechanical seal bushing are circumferentially fixedly arranged relative to each other.

[0014] In a preferred embodiment of this utility model, a limiting block is connected to the end of the atmospheric side pressure cover away from the inner sealing box, and the limiting block axially locks and positions the mechanical seal bushing.

[0015] In a preferred embodiment of the present invention, the second axial elastic compensation power unit includes a second spring and a spring box. The spring box is fixedly sleeved on the mechanical seal bushing. A second spring connecting groove is provided at one end of the spring box near the atmospheric side non-compensation ring. The two ends of the second spring are respectively abutted and connected to the bottom of the second spring connecting groove and the second end of the atmospheric side compensation ring. A third anti-rotation pin is provided between the spring box and the atmospheric side compensation ring.

[0016] In a preferred embodiment of the present invention, the inner sidewall of the atmospheric side pressure cover is provided with a second shoulder and a third shoulder, and a fourth anti-rotation pin is provided between the sidewall of the atmospheric side pressure cover located between the second shoulder and the third shoulder and the atmospheric side non-compensation ring. The fourth shoulder is provided on the sidewall of the atmospheric side non-compensation ring, and the fourth shoulder seals against the second shoulder.

[0017] In a preferred embodiment of the present invention, the atmospheric pressure cover is provided with an isolation liquid outlet that conducts through the first isolation liquid annulus, the inner sealing box is provided with a plurality of first isolation liquid inlets that conduct through the second isolation liquid annulus, and the atmospheric pressure cover is provided with a second isolation liquid inlet that can communicate with the first isolation liquid inlet.

[0018] The purpose of this utility model can also be achieved by providing an axial flow pump, including the aforementioned mechanical seal structure for axial flow pumps.

[0019] As described above, the mechanical seal structure for axial flow pumps and the axial flow pump of this utility model have the following beneficial effects:

[0020] The mechanical seal bushing, medium-side sealing part, atmospheric-side sealing part and inner sealing box of this utility model constitute a cartridge mechanical seal structure. The mechanical seal structure for axial flow pumps of this utility model can be assembled before installation into the sealing space between the axial flow pump housing and the mechanical seal bushing. When installing the mechanical seal structure on site, there is no need for repeated adjustments, the impact on the sealing end face is small, the labor intensity and human installation errors are reduced, and time is saved.

[0021] Pressurized isolation fluid is injected into the first isolation fluid annulus between the medium-side sealing part and the atmospheric-side sealing part, and the second isolation fluid annulus between the inner sealing box and the medium-side compensation ring. The pressure of the pressurized isolation fluid is higher than the medium pressure, which can prevent the medium on the medium side from carrying crystals into the sealing end face of the medium-side sealing part, effectively reducing pump shaft fluctuation, buffering radial wear, reducing damage to the sealing surface, and improving the service life of the mechanical seal structure for axial flow pumps.

[0022] This invention features a protective sleeve on the medium side, which protects the sealing end face of the medium side and prevents breakage and fluctuations caused by the impact of large crystals. The protective sleeve rotates together with the mechanical seal shaft sleeve, and large crystals are broken by the breakage notch when they approach the sealing end face, thereby improving the operational stability and service life of this invention.

[0023] This invention enables axial positioning of the mechanical seal bushing through a limiting block, reducing the influence of external factors.

[0024] The inner sealing chamber of this invention is provided with multiple isolation liquid inlets, which allow the isolation liquid to enter the first isolation liquid annulus and the second isolation liquid annulus evenly, effectively mitigating fluctuations. Attached Figure Description

[0025] The following figures are intended only to illustrate and explain the present invention and do not limit the scope of the present invention. Wherein:

[0026] Figure 1 This is a cross-sectional view of the mechanical seal structure for the axial flow pump of this utility model.

[0027] Figure 2 for Figure 1 Enlarged view of point A in the middle.

[0028] Figure 3 for Figure 1 View from direction B in the middle.

[0029] Figure 4 This is a structural diagram of the medium-side sealing part of this utility model.

[0030] Figure 5 This is a structural diagram of the atmospheric side sealing part of this utility model.

[0031] In the picture:

[0032] 100. Mechanical seal structure for axial flow pump; 101. First isolation fluid annulus; 102. Second isolation fluid annulus; 1. Mechanical seal shaft sleeve; 2. First O-ring seal; 3. Second O-ring seal; 4. Medium-side non-compensating ring; 5. Medium-side compensating ring; 6. Backflow sleeve; 7. Third O-ring seal; 8. Second anti-rotation pin; 9. Spring seat; 10. First spring; 11. Protective sleeve; 111. Breaking notch; 12. Spring box; 13. Set screw; 14. Second spring; 15. Fourth O-ring seal; 16. Third anti-rotation pin; 17. Atmospheric side makeup 18. Non-compensating ring on the atmospheric side; 19. Fifth O-ring seal; 20. Fourth anti-rotation pin; 21. Limiting block; 22. Locking ring; 23. First plug; 24. First fastening bolt; 25. Second plug; 26. Second fastening bolt; 27. Axial flow pump housing; 28. Sixth O-ring seal; 29. ​​Atmospheric side gland; 30. Seventh O-ring seal; 31. Eighth O-ring seal; 32. Third fastening bolt; 33. Inner sealing housing; 34. Ninth O-ring seal; 35. First anti-rotation pin; 36. Fourth fastening bolt; 37. Pump shaft. Detailed Implementation

[0033] To provide a clearer understanding of the technical features, objectives, and effects of this utility model, the specific embodiments of this utility model are now described with reference to the accompanying drawings.

[0034] The specific embodiments of the present invention described herein are for illustrative purposes only and should not be construed as limiting the present invention in any way. Under the teachings of this invention, those skilled in the art can conceive of any possible modifications based on this invention, and these should all be considered within the scope of this invention. It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intervening element. The terms "mounted," "connected," and "linked" should be interpreted broadly; for example, they can refer to mechanical or electrical connections, or internal connections between two elements, and can be direct or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible embodiments.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0036] This utility model provides a mechanical seal structure for an axial flow pump, which is disposed within the axial flow pump cavity between the axial flow pump housing 27 and the pump shaft 37 to achieve sealing of the axial flow pump. Figures 1 to 5 As shown, the mechanical seal structure 100 for axial flow pumps of this utility model includes a mechanical seal sleeve 1, a medium-side sealing part, an atmospheric-side sealing part, and an inner sealing housing 33. The mechanical seal sleeve 1 can be fixedly sleeved on the pump shaft 37 and rotates together with the pump shaft 37, playing a role in protecting the pump shaft, reducing friction, and sealing. The mechanical seal sleeve 1 and the pump shaft 37 can be sealed by a first O-ring seal 2. The inner sealing housing 33 is sealed between the medium-side sealing part, the axial flow pump housing 27, and the atmospheric-side sealing part, and can be integrated and assembled before being installed on the axial flow pump housing 27.

[0037] like Figure 1 , Figure 3 , Figure 4 As shown, a protective sleeve 11 is provided at one end of the mechanical seal bushing 1 near the sealing part on the medium side. The protective sleeve 11 can rotate with the mechanical seal bushing 1. The end of the protective sleeve 11 near the sealing part on the medium side is open. A breaking notch 111 is provided on the side wall of the protective sleeve 11 to break up crystals in the medium. In a specific embodiment, a threaded hole is provided on the end face of the mechanical seal bushing 1 on the medium side, and the protective sleeve 11 is connected to the mechanical seal bushing 1 by a fourth fastening bolt 36. The breaking notch 111 is a square notch for breaking up crystals.

[0038] The medium-side sealing part includes a medium-side compensating ring 5 disposed between the inner sealing housing 33 and the mechanical seal bushing 1, which can move axially for sealing and float radially for sealing to compensate for impact displacement; the atmospheric-side sealing part includes an atmospheric-side pressure cover 29 disposed between the inner sealing housing 33 and the mechanical seal bushing 1, the atmospheric-side pressure cover 29 being detachably and sealingly connected to the axial flow pump housing 27, specifically, a sixth O-ring seal 28 is provided between the atmospheric-side pressure cover 29 and the axial flow pump housing 27; at least one atmospheric-side compensating ring 17 that can move axially to compensate for impact displacement is provided between the inner side of the atmospheric-side pressure cover 29 and the mechanical seal bushing 1.

[0039] A first isolation fluid annulus 101 is provided between the radial inner side of the medium-side sealing part and the atmospheric-side sealing part and the mechanical seal bushing 1, and a second isolation fluid annulus 102 that can communicate with the first isolation fluid annulus 101 is provided between the inner sealing box 33 and the medium-side compensation ring 5.

[0040] The mechanical seal bushing 1, medium-side sealing part, atmospheric-side sealing part, and inner sealing housing 33 of this utility model constitute a cartridge mechanical seal structure. The mechanical seal structure for axial flow pumps can be assembled before installation into the sealing space between the axial flow pump housing 27 and the pump shaft 37. During on-site installation, repeated adjustments are unnecessary, minimizing the impact on the mechanical seal end face, reducing labor intensity and human error, and saving time. All component dimensions are designed and integrated according to their normal operating positions, requiring no adjustments to the mechanical seal structure before installation. This ensures the end face of the mechanical seal structure remains in its normal operating position, preventing human adjustment from causing the sealing end face to exceed the design parameter range.

[0041] Pressurized isolation fluid is injected into the first isolation fluid annulus 101 between the medium-side sealing part and the atmospheric-side sealing part, and the second isolation fluid annulus 102 between the inner sealing box 33 and the medium-side compensation ring 5. The pressure of the pressurized isolation fluid is higher than that of the medium, which can prevent the medium on the medium side from carrying crystals into the sealing end face of the medium-side sealing part, effectively reducing the fluctuation of the pump shaft, buffering radial wear, reducing damage to the sealing surface, and improving the service life of the mechanical seal structure for axial flow pumps.

[0042] The protective sleeve 11 can protect the sealing end face of the medium side of this utility model, avoiding breakage and fluctuation caused by the impact of large crystals. The protective sleeve 11 rotates together with the mechanical seal sleeve 1. When large crystals approach the sealing end face (the sealing surface between the medium side compensation ring 5 and the medium side non-compensation ring 4), they are broken by the breakage notch 111, thereby improving the operational stability and service life of this utility model.

[0043] Furthermore, such as Figure 1 , Figure 4 As shown, the medium-side sealing part includes a medium-side non-compensation ring 4, a medium-side compensation ring 5, and a first axial elastic compensation power part arranged in an axial abutment. The first end of the medium-side compensation ring 5 and the medium-side non-compensation ring 4 are exposed in the inner sealing housing 33. The inner side of one end of the medium-side non-compensation ring 4, the radial inner side of the medium-side compensation ring 5 and the first axial elastic compensation power part are arranged radially spaced from the mechanical seal bushing 1, forming the medium-side segment of the first isolation fluid annulus 101.

[0044] The medium-side non-compensating ring 4 seals against the first end of the mechanical seal sleeve 1 and the medium-side compensating ring 5. The first axial elastic compensating power unit axially abuts against the second end of the medium-side compensating ring 5 so that the first end of the medium-side compensating ring 5 remains sealed against the medium-side non-compensating ring 4. That is, the first axial elastic compensating power unit provides the axial force required for the medium-side compensating ring 5 and keeps it sealed against the medium-side non-compensating ring 4. The first axial elastic compensating power unit can move elastically, so that the medium-side compensating ring 5 can move axially. When the medium and the crystals therein impact the end face of this utility model, the medium-side compensating ring 5 moves axially to compensate for the axial impact displacement, ensuring that the first end of the medium-side compensating ring 5 remains sealed against the medium-side non-compensating ring 4, preventing the entry of crystal blocks, and playing a buffering role.

[0045] The medium-side non-compensation ring 4 and the mechanical seal bushing 1 are circumferentially fixed together, and the medium-side non-compensation ring 4 rotates synchronously with the mechanical seal bushing 1; the medium-side compensation ring 5 and the inner sealing box 33 are circumferentially fixed together, and the medium-side compensation ring 5 is circumferentially fixed.

[0046] Between the sealing end faces where the medium-side compensation ring 5 and the medium-side non-compensation ring 4 are fitted, a liquid film formed by the isolation fluid provides lubrication in the micro gaps (the micro-local area near the radial outer side can be lubricated by the external medium due to pressure; the gaps between the sealing end faces are very small, and crystals cannot enter, so there is no wear of the sealing end faces by crystals) and prevents the medium with crystals from entering the sealing end faces, thereby reducing the wear of the sealing surface.

[0047] Furthermore, such as Figure 1 , Figure 4 As shown, a backflow sleeve 6 is provided between the medium-side compensation ring 5 and the mechanical seal bushing 1. The inner wall of the backflow sleeve 6 and the mechanical seal bushing 1 are radially spaced apart, and the outer wall of the backflow sleeve 6 and the inner wall of the medium-side compensation ring 5 are radially spaced apart. The annular space between the inner wall of the backflow sleeve 6 and the mechanical seal bushing 1 is the first isolation fluid annular space 101, and the annular space between the outer wall of the backflow sleeve 6 and the inner wall of the medium-side compensation ring 5 is the second isolation fluid annular space 102. The end of the backflow sleeve 6 near the medium-side non-compensation ring 4 is open. The end of the backflow sleeve 6 away from the medium-side non-compensation ring 4 is fixed between the inner sealing box 33 and the atmospheric pressure cover 29.

[0048] Furthermore, such as Figure 1 , Figure 4 As shown, the first axial elastic compensation power unit includes a first spring 10 and a spring seat 9. The end of the spring seat 9 away from the non-compensation ring 4 on the medium side is provided with a first spring connecting groove. The two ends of the first spring 10 are respectively connected to the bottom of the first spring connecting groove and the end of the backflow sleeve 6 away from the non-compensation ring 4 on the medium side. The first spring 10 provides spring force to keep the compensation ring 5 on the medium side always axially attached to the non-compensation ring 4 on the medium side.

[0049] One end of the spring seat 9 near the medium-side non-compensating ring 4 is connected to the second end of the medium-side compensating ring 5. The end of the spring seat 9 away from the medium-side non-compensating ring 4 is axially spaced from the backflow sleeve 6. The side wall of the spring seat 9 away from the mechanical seal sleeve 1 is radially spaced from the inner wall of the inner sealing housing 33. The annular space between the side wall of the spring seat 9 away from the mechanical seal sleeve 1 and the inner wall of the inner sealing housing 33 is the second isolation fluid annular space 102. The axial space between the spring seat 9 and the backflow sleeve 6 connects the second isolation fluid annular space 102 and the first isolation fluid annular space 101. The first isolation fluid annular space 101 and the second isolation fluid annular space 102 are filled with pressurized isolation fluid, which can buffer the radial fluctuation of the pump shaft and reduce the impact caused by the pump shaft fluctuation.

[0050] Furthermore, such as Figure 1 , Figure 4 As shown, a first anti-rotation pin 35 is provided between the medium-side uncompensated ring 4 and the mechanical seal bushing 1. The first anti-rotation pin 35 prevents relative rotation between the medium-side uncompensated ring 4 and the mechanical seal bushing 1, ensuring that the medium-side uncompensated ring 4 can rotate synchronously with the mechanical seal bushing 1. Specifically, a first compensation ring slot through which the first anti-rotation pin 35 passes is provided on the medium-side uncompensated ring 4, and a bushing interface for inserting the first anti-rotation pin 35 is provided on the side wall of the mechanical seal bushing 1.

[0051] A first shoulder is provided on the medium-side non-compensation ring 4, and the first shoulder abuts the end of the mechanical seal bushing 1 axially. A bushing medium-side sealing part is provided between the inner wall of the medium-side non-compensation ring 4 and the outer wall of the end of the mechanical seal bushing 1. In a specific embodiment, the bushing medium-side sealing part is a second O-ring seal 3.

[0052] Furthermore, such as Figure 1 , Figure 2 , Figure 4 As shown, a floating second anti-rotation pin 8 is provided between the inner sealing housing 33 and the medium-side compensation ring 5. Specifically, a housing pin hole is provided on the inner sealing housing 33. To prevent the second anti-rotation pin 8 from falling off, a third fastening bolt 32 is threaded to the top of the housing pin hole. There is an axial gap between the third fastening bolt 32 and the second anti-rotation pin 8, and a floating gap is provided between the second anti-rotation pin 8 and the housing pin hole. A second compensation ring groove is provided on the medium-side compensation ring 5. The contact surface between the second anti-rotation pin 8 and the second compensation ring groove is flat, ensuring that the second anti-rotation pin 8 can slightly adjust the contact surface according to the direction of force during operation, and always maintain a fine adjustment angle during operation to meet the floating requirements of the medium-side compensation ring 5.

[0053] An inner sealing portion for the inner sealing housing 33 is provided between the second anti-rotation pin 8 and the media-side compensation ring 5 on the side near the media-side non-compensation ring 4. Specifically, the inner sealing portion for the media-side is a third O-ring 7 to prevent the media from mixing with the isolation liquid. In one specific embodiment, the second anti-rotation pin 8 (floating anti-rotation pin) adopts a T-shaped structure.

[0054] The outer wall of the inner sealing housing 33 is spaced apart from the inner wall of the axial flow pump housing 27, and an inner housing sealing part is provided between the outer wall of the end of the inner sealing housing 33 and the axial flow pump housing 27; specifically, the inner housing sealing part is a ninth O-ring seal 34.

[0055] An inner sealing chamber atmospheric side sealing part is provided between the inner sealing chamber 33 and the atmospheric side pressure cover 29. Specifically, a fifth shoulder is provided on the inner wall of the atmospheric side pressure cover 29, and a chamber protrusion ring extending into the atmospheric side pressure cover 29 is provided at the end of the inner sealing chamber 33 away from the medium-side non-compensation ring 4. The end of the backflow sleeve 6 away from the medium-side non-compensation ring 4 is fixed between the end face of the chamber protrusion ring and the fifth shoulder. The inner sealing chamber atmospheric side sealing part includes an eighth O-ring 31 between the axial end faces of the inner sealing chamber 33 and the atmospheric side pressure cover 29, and a seventh O-ring 30 between the chamber protrusion ring and the inner wall of the atmospheric side pressure cover 29. The inner sealing chamber 33 and the atmospheric side pressure cover 29 are fixedly connected by a first fastening bolt 24.

[0056] Furthermore, such as Figure 1 , Figure 5 As shown, the atmospheric side sealing part includes an atmospheric side non-compensating ring 18, an atmospheric side compensating ring 17, and a second axial elastic compensation power part. The atmospheric side non-compensating ring 18 axially abuts against the atmospheric side pressure plate 29 and the atmospheric side compensating ring 17. The second axial elastic compensation power part axially abuts against the second end of the atmospheric side compensating ring 17 so that the first end of the atmospheric side compensating ring 17 is sealed against the atmospheric side non-compensating ring 18. The atmospheric side non-compensating ring 18 and the atmospheric side pressure plate 29 are circumferentially fixedly arranged. The atmospheric side compensating ring 17 and the mechanical seal bushing 1 are circumferentially fixedly arranged.

[0057] Furthermore, such as Figure 1 , Figure 5 As shown, the end of the atmospheric side pressure cover 29 away from the inner sealing box 33 is connected to a limiting block 21, and the limiting block 21 is axially locked onto the mechanical seal bushing 1. Specifically, a limiting groove is provided on the outer wall of the mechanical seal bushing 1, and the limiting block 21 is locked into the limiting groove. The limiting block 21 is connected to the atmospheric side pressure cover 29 by a second fastening bolt 26.

[0058] Because the pump shaft of an axial flow pump is generally quite long, and the axial flow pump is fixed on the process pipeline, the process medium expands and contracts due to temperature changes after the axial flow pump is running. This utility model has fewer positioning connections with the axial flow pump cavity, and the limiting block 21 can be used to achieve axial positioning of the mechanical seal sleeve, reducing the influence of external factors.

[0059] Furthermore, such as Figure 1 , Figure 5 As shown, the second axial elastic compensation power unit includes a second spring 14 and a spring box 12. The spring box 12 is fixedly sleeved on the mechanical seal bushing 1. Specifically, the spring box 12 is connected to the mechanical seal bushing 1 by a set screw 13, and a protruding collar is provided on the mechanical seal bushing 1. The end of the spring box 12 away from the atmosphere side non-compensation ring 18 axially abuts against the end face of the collar for axial limiting.

[0060] A second spring connecting groove is provided at one end of the spring box 12 near the atmospheric side non-compensation ring 18. The two ends of the second spring 14 are respectively connected to the bottom of the second spring connecting groove and the second end of the atmospheric side compensation ring 17. The second spring 14 provides spring force to keep the atmospheric side compensation ring 17 always axially attached to the atmospheric side non-compensation ring 18.

[0061] A third anti-rotation pin 16 is provided between the spring box 12 and the atmospheric side compensation ring 17. The atmospheric side compensation ring 17 is circumferentially fixed to the mechanical seal bushing 1 by the third anti-rotation pin 16, the spring box 12 and the set screw 13, so that it can rotate synchronously with the mechanical seal bushing 1.

[0062] To ensure a good seal, a fourth O-ring 15 is provided between the atmospheric side compensation ring 17 and the mechanical seal bushing 1.

[0063] Furthermore, such as Figure 1 , Figure 5 As shown, the inner wall of the atmospheric side pressure cover 29 is provided with a second shoulder and a third shoulder. A fourth anti-rotation pin 20 is provided between the side wall of the atmospheric side pressure cover 29 between the second shoulder and the third shoulder and the atmospheric side non-compensation ring 18. A fourth shoulder is provided on the side wall of the atmospheric side non-compensation ring 18. The fourth shoulder seals against the second shoulder. Specifically, the fourth shoulder and the second shoulder are sealed by a fifth O-ring seal 19.

[0064] Furthermore, a locking ring 22 is fitted on one end of the mechanical seal bushing 1 that extends to the atmosphere. The locking ring 22 fixes the mechanical seal bushing 1 to the pump shaft 37, preventing relative axial and radial movement between the mechanical seal bushing 1 and the pump shaft 37.

[0065] Furthermore, such as Figure 1 , Figure 5As shown, the atmospheric pressure cover 29 is provided with an isolation liquid outlet that connects to the first isolation liquid annulus 101, and the inner sealing box 33 is provided with multiple first isolation liquid inlets that connect to the second isolation liquid annulus 102. The atmospheric pressure cover 29 is provided with a second isolation liquid inlet that can communicate with the first isolation liquid inlet. The isolation liquid enters the second isolation liquid annulus 102 and the first isolation liquid annulus 101 through the second isolation liquid inlet, the annulus between the axial flow pump housing 27 and the inner sealing box 33, and the first isolation liquid inlet. The isolation liquid flows out of the first isolation liquid annulus 101 through the isolation liquid outlet.

[0066] To avoid pressure fluctuations from a single point of entry of the isolation fluid, multiple first isolation fluid inlets are provided on the inner sealing housing 33, so that the isolation fluid enters the first isolation fluid annulus 101 and the second isolation fluid annulus 102 evenly, effectively mitigating the fluctuations.

[0067] In one specific embodiment, the inner sealing housing 33 is provided with four first isolation liquid inlets; the atmospheric side pressure cover 29 is provided with two second isolation liquid inlets and two isolation liquid outlets, one of which is a commonly used port and the other is a spare port. When not in use, they are sealed by the second plug 25 and the first plug 23 respectively. The multiple second isolation liquid inlets and outlets facilitate the application of various pipeline connections.

[0068] This utility model also provides an axial flow pump, including the aforementioned mechanical seal structure 100 for axial flow pumps. The mechanical seal structure 100 for axial flow pumps is disposed in the axial flow pump cavity between the axial flow pump housing 27 and the pump shaft 37, thereby achieving a seal for the axial flow pump.

[0069] The above description is merely an illustrative embodiment of this utility model and is not intended to limit the scope of this utility model. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of this utility model should fall within the protection scope of this utility model.

Claims

1. A mechanical seal structure for an axial flow pump, characterized in that, The system includes a mechanical seal bushing, a medium-side sealing portion, an atmospheric-side sealing portion, and an inner sealing housing. The inner sealing housing is sealed between the medium-side sealing portion, the axial flow pump housing, and the atmospheric-side sealing portion. A protective sleeve is provided at one end of the mechanical seal bushing near the medium-side sealing portion, and the side wall of the protective sleeve has a breakage notch capable of rotating and breaking crystals within the medium. The medium-side sealing portion includes a medium-side compensating ring disposed between the inner sealing housing and the mechanical seal bushing, capable of axial sealing movement and radial floating to compensate for impact displacement. The atmospheric-side sealing portion includes an atmospheric-side pressure cap disposed between the inner sealing housing and the mechanical seal bushing, and detachably connected to the axial flow pump housing. An atmospheric-side compensating ring capable of axial movement to compensate for impact displacement is provided between the inner side of the atmospheric-side pressure cap and the mechanical seal bushing. A first isolation fluid annulus is provided between the radially inner sides of the medium-side sealing portion and the atmospheric-side sealing portion and the mechanical seal bushing, and a second isolation fluid annulus capable of communicating with the first isolation fluid annulus is provided between the inner sealing housing and the medium-side compensating ring.

2. The mechanical seal structure for an axial flow pump as described in claim 1, characterized in that, The medium-side sealing portion includes a medium-side non-compensating ring, a medium-side compensating ring, and a first axial elastic compensating power unit arranged axially abutting against each other. The first end of the medium-side compensating ring and the medium-side non-compensating ring are exposed outside the inner sealing housing. The inner side of one end of the medium-side non-compensating ring, the radial inner side of the medium-side compensating ring and the first axial elastic compensating power unit are radially spaced from the mechanical seal bushing. The medium-side non-compensating ring seals against the mechanical seal bushing and the first end of the medium-side compensating ring, and the first axial elastic compensating power unit axially abuts against the second end of the medium-side compensating ring to keep the first end of the medium-side compensating ring sealing against the medium-side non-compensating ring. The medium-side non-compensating ring and the mechanical seal bushing are circumferentially fixed relative to each other. The medium-side compensating ring and the inner sealing housing are circumferentially fixed relative to each other.

3. The mechanical seal structure for an axial flow pump as described in claim 2, characterized in that, A backflow sleeve is provided between the medium-side compensation ring and the mechanical seal bushing. The inner wall of the backflow sleeve and the mechanical seal bushing are radially spaced apart, and the outer wall of the backflow sleeve and the inner wall of the medium-side compensation ring are radially spaced apart. The end of the backflow sleeve near the medium-side non-compensation ring is open. The end of the backflow sleeve away from the medium-side non-compensation ring is fixed between the inner sealing box and the atmospheric pressure cover.

4. The mechanical seal structure for an axial flow pump as described in claim 3, characterized in that, The first axial elastic compensation power unit includes a first spring and a spring seat. The end of the spring seat away from the non-compensation ring on the medium side is provided with a first spring connecting groove. The two ends of the first spring are respectively abutted and connected to the bottom of the first spring connecting groove and the end of the backflow sleeve away from the non-compensation ring on the medium side. The end of the spring seat near the non-compensation ring on the medium side is connected to the second end of the compensation ring on the medium side. The end of the spring seat away from the non-compensation ring on the medium side is axially spaced from the backflow sleeve. The side wall of the spring seat away from the mechanical seal sleeve is radially spaced from the inner wall of the inner sealing box.

5. The mechanical seal structure for an axial flow pump as described in claim 2, characterized in that, A first anti-rotation pin is provided between the medium-side non-compensation ring and the mechanical seal bushing; a first shoulder is provided on the medium-side non-compensation ring, the first shoulder abuts axially against the end head of the mechanical seal bushing, and a bushing medium-side sealing part is provided between the inner wall of the medium-side non-compensation ring and the outer wall of the end head of the mechanical seal bushing.

6. The mechanical seal structure for an axial flow pump as described in claim 2, characterized in that, A floating second anti-rotation pin is provided between the inner sealing box and the medium-side compensation ring. An inner box medium-side sealing part is provided between the inner wall of the inner sealing box and the medium-side compensation ring on the side of the second anti-rotation pin near the medium-side non-compensation ring. The outer wall of the inner sealing box is spaced apart from the inner wall of the axial flow pump housing, and an inner box housing sealing part is provided between the end outer wall of the inner sealing box and the axial flow pump housing. An inner box atmospheric-side sealing part is provided between the inner sealing box and the atmospheric-side pressure cover.

7. The mechanical seal structure for an axial flow pump as described in claim 2, characterized in that, The atmospheric side sealing part includes an atmospheric side non-compensating ring, an atmospheric side compensating ring, and a second axial elastic compensating power part. The atmospheric side non-compensating ring axially abuts against the atmospheric side pressure cap and the atmospheric side compensating ring. The second axial elastic compensating power part axially abuts against the second end of the atmospheric side compensating ring so that the first end of the atmospheric side compensating ring remains sealed against the atmospheric side non-compensating ring. The atmospheric side non-compensating ring and the atmospheric side pressure cap are circumferentially fixed to each other. The atmospheric side compensating ring and the mechanical seal bushing are circumferentially fixed to each other.

8. The mechanical seal structure for an axial flow pump as described in claim 7, characterized in that, The end of the atmospheric pressure cover away from the inner sealing box is connected to a limiting block, which axially locks and positions the mechanical seal bushing.

9. The mechanical seal structure for an axial flow pump as described in claim 7, characterized in that, The second axial elastic compensation power unit includes a second spring and a spring box. The spring box is fixedly sleeved on the mechanical seal bushing. A second spring connecting groove is provided at one end of the spring box near the atmospheric side non-compensation ring. The two ends of the second spring are respectively abutted and connected to the bottom of the second spring connecting groove and the second end of the atmospheric side compensation ring. A third anti-rotation pin is provided between the spring box and the atmospheric side compensation ring.

10. The mechanical seal structure for an axial flow pump as described in claim 7, characterized in that, The inner wall of the atmospheric side pressure cover is provided with a second shoulder and a third shoulder. A fourth anti-rotation pin is provided between the side wall of the atmospheric side pressure cover between the second shoulder and the third shoulder and the atmospheric side non-compensation ring. A fourth shoulder is provided on the side wall of the atmospheric side non-compensation ring. The fourth shoulder seals against the second shoulder.

11. The mechanical seal structure for an axial flow pump as described in claim 1, characterized in that, The atmospheric pressure cover is provided with an isolation liquid outlet that conducts through the first isolation liquid annulus, the inner sealing box is provided with multiple first isolation liquid inlets that conduct through the second isolation liquid annulus, and the atmospheric pressure cover is provided with a second isolation liquid inlet that can communicate with the first isolation liquid inlet.

12. An axial flow pump, characterized in that, Includes the mechanical seal structure for axial flow pumps as described in any one of claims 1 to 11.

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