Self-injection structure of centrifugal pump

Abstract

The utility model discloses a self-ejection structure of a centrifugal pump. The self-ejection structure comprises a machine shell, an inducer, an ejector, an impeller and a main shaft. The machine shell is a cavity shell provided with a liquid inlet and a liquid outlet. The end part of the main shaft extends into the shell; the impeller is arranged on the outer side of the main shaft in a sleeving mode and arranged in the machine shell. The inducer is connected to the end, close to the impeller, of the spindle. The ejector is arranged on the outer side of the inducer in a sleeving manner, and the ejector is connected to the interior of the machine shell; and the shell and the ejector are provided with a jet flow channel in the radial direction. The problems that in the prior art, a cavitation phenomenon exists when a pump set inducer rotates at a high speed, so that the efficiency of a pump set is reduced, and vibration and noise are generated are solved. The technical effects that the leading edge vortex of the inducer is eliminated, the cavitation performance of the inducer is improved, and the anti-cavitation capacity of the pump set is improved are achieved.

Description

Technical Field

[0001] The present application relates to the technical field of centrifugal pumps, and in particular to a self-ejection structure of a centrifugal pump. Background Art

[0002] Compound impeller centrifugal pumps with front inducers are widely used fluid machinery, offering numerous advantages in terms of energy transfer efficiency, stability, and pressure capacity. With the continuous advancement of technology, researchers are continuously improving and optimizing these centrifugal pumps to enhance their performance.

[0003] Currently, inducers are axial-flow impellers. When rotating at high speed, the high peripheral speed and the impact of leakage flow through the impeller tip clearance can cause a sudden drop in the inducer inlet pressure. When the inlet pressure falls below the local vapor pressure, cavitation occurs. This cavitation reduces pump efficiency and is accompanied by vibration and noise. It can also cavitate hydraulic components such as the inducer, potentially resulting in serious consequences. Therefore, inducer cavitation needs to be addressed urgently. Utility Model Content

[0004] The embodiment of the present application solves the problem in the prior art that cavitation occurs when the inducer rotates at high speed, thereby reducing the efficiency of the pump group and generating vibration and noise, by providing a self-ejection structure for a centrifugal pump.

[0005] An embodiment of the present utility model provides a self-ejection structure of a centrifugal pump, comprising a casing, an inducer, an ejector, an impeller and a main shaft; the casing is a hollow shell provided with a liquid inlet and a liquid outlet; the end of the main shaft extends into the interior of the casing; the impeller is sleeved on the outside of the main shaft, and the impeller is arranged inside the casing; the inducer is connected to the end of the main shaft close to the impeller; the ejector is sleeved on the outside of the inducer, and the ejector is connected to the interior of the casing; the casing and the ejector are provided with jet channels in the radial direction.

[0006] In a possible implementation, a first sealing ring is further included; the first sealing ring is sleeved on the outer side of the impeller, and the first sealing ring is connected to the inner side of the casing; a first sealing gap is provided between the first sealing ring and the impeller in the radial direction.

[0007] In a possible implementation, it also includes a machine cover and a second sealing ring; the machine cover is a hollow shell; one end of the machine cover is sleeved on the outside of the impeller, and the machine cover is connected to the end of the shell away from the liquid inlet; the second sealing ring is sleeved on the outside of the impeller, and the second sealing ring is connected to the inside of the machine cover; the second sealing ring and the impeller are provided with a second sealing gap in the radial direction.

[0008] In a possible implementation, a connecting shaft is further included; the connecting shaft is connected to one end of the main shaft close to the liquid inlet; the inducer is sleeved on the outside of the connecting shaft and connected to the connecting shaft.

[0009] In one possible implementation, the ejector includes a fixed ring and a de-rotation plate; the de-rotation plate is connected to the outer side of the fixed ring; the fixed ring is sleeved on the outer side of the inducer; the de-rotation plate is connected to the inner side of the casing; and the jet channel is provided between the fixed ring and the casing.

[0010] In one possible implementation, the inducer includes a hub and a plurality of blades; the plurality of blades are connected to the outer side of the hub at intervals; the hub is sleeved on the outer side of the connecting shaft and connected to the connecting shaft; the ejector is sleeved on the outer side of the blades, and a blade tip gap is provided between the ejector and the blades in the radial direction.

[0011] In a possible implementation, a bearing is further included; the bearing is arranged between the main shaft and the machine cover.

[0012] In a possible implementation, a fixed blade cascade is further included; the fixed blade cascade is connected to a channel of the casing near the liquid inlet.

[0013] In a possible implementation, the housing further includes reinforcing ribs; the reinforcing ribs are arranged on the outside of the housing.

[0014] In a possible implementation, an axial gap is provided between the impeller and the ejector in the axial direction; and a front chamber is provided between the impeller and the casing.

[0015] One or more technical solutions provided in this application have at least the following technical effects:

[0016] The embodiment of the present utility model adopts a self-ejection structure of a centrifugal pump, including a casing, an inducer, an ejector, an impeller and a main shaft; the ejector is sleeved on the outside of the inducer and connected to the inside of the casing; a jet channel is provided in the radial direction between the casing and the ejector; a first sealing gap is provided in the radial direction between the first sealing ring and the impeller; a front chamber is provided between the impeller and the casing, when the pump group is operating normally, a small amount of high-pressure fluid at the outlet of the impeller flows through the front chamber through the first sealing gap, part of the fluid passing through the first sealing gap enters the jet channel, and another part of the fluid passing through the first sealing gap flows to the inlet of the impeller through the axial gap between the impeller and the ejector, wherein the fluid entering the jet channel can be ejected from the outlet of the jet channel to the leading edge of the inducer, thereby increasing the pressure at the leading edge of the inducer, and can effectively reduce the leakage fluid of the inducer at the blade tip gap, thereby reducing the leading edge vortex of the inducer, improving the cavitation performance of the inducer, and enhancing the anti-cavitation ability of the pump group. This application solves the existing problem of cavitation when the inducer rotates at high speed, which reduces pump efficiency and generates vibration and noise. It achieves the technical effect of reducing the leading edge vortex of the inducer, improving the cavitation performance of the inducer, and enhancing the anti-cavitation capability of the pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 A cross-sectional view of a centrifugal pump self-ejection structure provided in an embodiment of the present application;

[0019] Figure 2 for Figure 1 A magnified view of point A;

[0020] Figure 3 An axonometric view of an ejector provided in an embodiment of the present application;

[0021] Figure 4 This is an axonometric view of the inducer provided in an embodiment of the present application.

[0022] Icons: 1- casing; 2- inducer; 21- hub; 22- blades; 23- tip clearance; 3- ejector; 31- fixed ring; 32- anti-rotation plate; 33- jet channel; 34- axial clearance; 4- impeller; 5- main shaft; 6- first sealing ring; 61- first sealing clearance; 7- machine cover; 8- second sealing ring; 81- second sealing clearance; 9- connecting shaft; 10- bearing; 11- fixed blade cascade; 12- reinforcing rib; 13- front chamber. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] In the description of the embodiments of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" 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 embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limitations on the present invention. The terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. In addition, 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 a communication between the internal parts of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to the specific circumstances.

[0025] At present, there are two main solutions to the cavitation of inducer 2. One is to optimize the geometric parameters of inducer 2 to improve the cavitation performance of inducer 2. The other is to use an external pipeline to guide the high-pressure fluid to the inlet of inducer 2, thereby compensating for the inlet pressure to improve the cavitation performance of inducer 2. However, the external pipeline will cause the pump group to be bulky, making the operating system more complicated, and there is also the problem of uneven pressure compensation in the inlet area of ​​​​inducer 2. Therefore, on the basis of not changing the external structure of the pump group, the present application utilizes a part of the space of the casing 1 to design an ejector 3, and the ejector 3 is connected to the first sealing gap 61 to form a self-ejection structure. The technical effects of reducing the leading edge vortex of inducer 2, improving the cavitation performance of inducer 2, and enhancing the anti-cavitation ability of the pump group are achieved.

[0026] The present invention provides a centrifugal pump self-ejection structure. Figure 1-4As shown, it includes a casing 1, an inducer 2, an ejector 3, an impeller 4 and a main shaft 5; the casing 1 is a hollow shell with a liquid inlet and a liquid outlet; the end of the main shaft 5 extends into the interior of the casing 1; the impeller 4 is sleeved on the outside of the main shaft 5, and the impeller 4 is arranged inside the casing 1; the inducer 2 is connected to the end of the main shaft 5 close to the impeller 4; the ejector 3 is sleeved on the outside of the inducer 2, and the ejector 3 is connected to the interior of the casing 1; the casing 1 and the ejector 3 are provided with a jet channel 33 in the radial direction.

[0027] For example, when the pump group is operating normally, a small amount of high-pressure fluid exists at the outlet of the impeller 4, flowing through the front chamber 13 and the first sealing gap 61. Part of the fluid passing through the first sealing gap 61 enters the jet channel 33, and another part of the fluid passing through the first sealing gap 61 flows to the inlet of the impeller 4 through the axial gap 34 between the impeller 4 and the ejector 3. The fluid entering the jet channel 33 can be ejected from the outlet of the jet channel 33 to the leading edge of the inducer 2, thereby increasing the pressure at the leading edge of the inducer 2, and can effectively reduce the leakage of the inducer 2 at the blade tip gap 23, thereby reducing the leading edge vortex of the inducer 2, improving the cavitation performance of the inducer 2, and enhancing the anti-cavitation ability of the pump group.

[0028] In the embodiment of this application, Figure 1-4 As shown, it also includes a first sealing ring 6; the first sealing ring 6 is sleeved on the outside of the impeller 4, and the first sealing ring 6 is connected to the inner side of the casing 1; the first sealing ring 6 and the impeller 4 are provided with a first sealing gap 61 in the radial direction.

[0029] Illustratively, the first sealing ring 6 is coaxially arranged with the ejector 3 and connected to the housing 1 via fastening screws. A first sealing gap 61 is formed between the first sealing ring 6 and the impeller 4. The first sealing gap 61 prevents collision between the impeller 4 and the first sealing ring 6. Furthermore, the first sealing gap 61 can guide the high-pressure fluid into the jet channel 33.

[0030] In the embodiment of this application, Figure 1-4 As shown, the self-ejection structure of the centrifugal pump also includes a machine cover 7 and a second sealing ring 8; the machine cover 7 is a cavity shell; one end of the machine cover 7 is sleeved on the outside of the impeller 4, and the machine cover 7 is connected to the end of the casing 1 away from the liquid inlet; the second sealing ring 8 is sleeved on the outside of the impeller 4, and the second sealing ring 8 is connected to the inside of the machine cover 7; the second sealing ring 8 and the impeller 4 are provided with a second sealing gap 81 in the radial direction.

[0031] Illustratively, the second sealing gap 81 can prevent the impeller 4 from colliding with the second sealing ring 8; and can also guide a small amount of fluid to the bearing 10, thereby lubricating the bearing 10. It should be noted that the medium of the pump group is generally a viscous fluid.

[0032] In the embodiment of this application, Figure 1-4 As shown, the centrifugal pump self-ejection structure also includes a connecting shaft 9; the connecting shaft 9 is connected to one end of the main shaft 5 close to the liquid inlet; the inducer 2 is sleeved on the outside of the connecting shaft 9 and connected to the connecting shaft 9.

[0033] In the embodiment of this application, Figure 1-4 As shown, the ejector 3 includes a fixed ring 31 and a de-rotation plate 32; the de-rotation plate 32 is connected to the outer side of the fixed ring 31; the fixed ring 31 is sleeved on the outer side of the inducer 2; the de-rotation plate 32 is connected to the inner side of the casing 1; a jet channel 33 is provided between the fixed ring 31 and the casing 1.

[0034] Exemplarily, the structure of the ejector 3 is annular, and a plurality of de-rotation plates 32 are provided. The plurality of de-rotation plates 32 are evenly arranged circumferentially around the fixed ring 31. The space between two adjacent de-rotation plates 32 forms a jet channel 33 together with the outer wall of the fixed ring 31 and the inner wall of the casing 1.

[0035] In the embodiment of this application, Figure 1-4 As shown, the inducer 2 includes a hub 21 and a plurality of blades 22; the plurality of blades 22 are connected to the outer side of the hub 21 at intervals; the hub 21 is sleeved on the outer side of the connecting shaft 9 and is connected to the connecting shaft 9; the ejector 3 is sleeved on the outer side of the blades 22, and a blade tip gap 23 is provided between the ejector 3 and the blades 22 in the radial direction.

[0036] Exemplarily, the de-rotation plate 32 is connected to the casing 1 by fastening screws; the outer cylindrical surface of the de-rotation plate 32 fits against the inner wall of the casing 1; a mounting groove is provided on the casing 1, the de-rotation plate 32 is arranged in the mounting groove, and the end of the de-rotation plate 32 close to the liquid inlet is in contact with the casing 1.

[0037] Exemplarily, a gap of 0.1 mm to 0.15 mm is maintained between the ejector 3 and the impeller 4 to prevent collision between the impeller 4 and the ejector 3 .

[0038] Exemplarily, a plurality of jet channels 33 are provided, and the plurality of jet channels 33 are evenly arranged in the circumferential direction of the fixed ring 31. The inlet of the jet channel 33 is connected to the first sealing gap 61, and the outlet of the jet channel 33 is connected to the leading edge of the inducer 2. The outlet of the jet channel 33 of the present application has a smooth transition, thereby reducing the jet loss.

[0039] Exemplarily, the depth of the jet channel 33 is 3-5 times that of the first sealing gap 61 , the purpose of which is to decelerate and pressurize the jet, thereby compensating for the higher pressure at the leading edge of the inducer 2 ;

[0040] Exemplarily, the function of jet channel 33 is to guide the high-pressure fluid in first sealing gap 61 to flow to the leading edge of inducer 2, thereby increasing the pressure at the leading edge of inducer 2, eliminating the leading edge vortex, and also preventing backflow from occurring in blade tip gap 23 of inducer 2, thereby improving the cavitation characteristics of inducer 2.

[0041] Exemplarily, the multiple anti-rotation plates 32 are all arc partitions, and the multiple anti-rotation plates 32 are evenly distributed in the circumferential direction of the fixed ring 31. The number of anti-rotation plates 32 is equal to the number of jet channels 33, and is usually 4n. The value of n is a positive integer. The smaller the size of the pump group, the smaller the value of n.

[0042] For example, the function of the de-swirl plate 32 is to suppress the high-pressure jet in the jet channel 33 from forming a circumferential vortex, which can reduce the jet loss; and the de-swirl plate 32 can also be installed in the casing 1 to position the ejector 3 as a whole.

[0043] Exemplarily, inducer 2 is located between fixed blade cascade 11 and impeller 4, and is arranged on the same central axis as impeller 4. Inducer 2 is fixedly connected to connecting shaft 9 through the internal thread of hub 21. During installation, the end face of inducer 2 is positioned in coordination with the end face of impeller 4.

[0044] Exemplarily, the inducer 2 includes a constant pitch inducer 2 and a variable pitch inducer 2 , and the number of blades 22 of the inducer 2 is usually set to 2 or 3; the inducer 2 can increase the inlet pressure of the impeller 4, thereby reducing the cavitation phenomenon of the impeller 4.

[0045] In the embodiment of this application, Figure 1-4 As shown, a bearing 10 is also included; the bearing 10 is arranged between the main shaft 5 and the machine cover 7.

[0046] In the embodiment of this application, Figure 1-4 As shown, the machine body further includes a fixed blade cascade 11 ; the fixed blade cascade 11 is connected to a channel of the casing 1 near the liquid inlet.

[0047] Exemplarily, the fixed blade 11 is arranged in the liquid inlet channel of the casing 1. A plurality of fixed blades 11 are provided, and the plurality of fixed blades 11 are evenly distributed in the circumferential direction of the casing 1. The fixed blade 11 has a flow-guiding function, which can eliminate the inlet vortex of the inducer 2, thereby preventing the vortex from spreading upstream.

[0048] For example, the number of fixed blades 11 is generally 1-2, and the effect is best when the number is coprime with the number of blades 22 .

[0049] In the embodiment of this application, Figure 1-4 As shown, the housing 1 further includes a reinforcing rib 12 ; the reinforcing rib 12 is arranged on the outer side of the housing 1 .

[0050] Exemplarily, a plurality of reinforcing ribs 12 are evenly arranged on the outer side of the casing 1 in the circumferential direction. The function of the reinforcing ribs 12 is to strengthen the strength of the casing 1, reduce the weight of the casing 1 while meeting the strength of the casing 1, and prevent the casing 1 from deforming at the jet channel 33.

[0051] In the embodiment of this application, Figure 1-4 As shown, an axial gap 34 is provided between the impeller 4 and the ejector 3 in the axial direction; a front chamber 13 is provided between the impeller 4 and the casing 1 .

[0052] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other. Each embodiment focuses on the differences from other embodiments.

[0053] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some or all of the technical features therein can be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. A centrifugal pump self-ejection structure, characterized in that: It comprises a casing (1), an inducer (2), an ejector (3), an impeller (4) and a main shaft (5); The housing (1) is a hollow housing with a liquid inlet and a liquid outlet; The end of the main shaft (5) extends into the interior of the housing (1); The impeller (4) is sleeved on the outside of the main shaft (5), and the impeller (4) is arranged inside the casing (1); The inducer (2) is connected to the end of the main shaft (5) close to the impeller (4); The ejector (3) is sleeved on the outside of the inducer (2), and the ejector (3) is connected to the inside of the casing (1); The housing (1) and the ejector (3) are provided with a jet channel (33) in the radial direction.

2. The centrifugal pump self-ejection structure according to claim 1, characterized in that: Also includes a first sealing ring (6); The first sealing ring (6) is sleeved on the outer side of the impeller (4), and the first sealing ring (6) is connected to the inner side of the casing (1); The first sealing ring (6) and the impeller (4) are provided with a first sealing gap (61) in the radial direction.

3. The centrifugal pump self-ejection structure according to claim 1, characterized in that: It also includes a machine cover (7) and a second sealing ring (8); The machine cover (7) is a cavity shell; One end of the machine cover (7) is sleeved on the outside of the impeller (4), and the machine cover (7) is connected to an end of the housing (1) away from the liquid inlet; The second sealing ring (8) is sleeved on the outer side of the impeller (4), and the second sealing ring (8) is connected to the inner side of the machine cover (7); The second sealing ring (8) and the impeller (4) are provided with a second sealing gap (81) in the radial direction.

4. The centrifugal pump self-ejection structure according to claim 1, characterized in that: Also includes a connecting shaft (9); The connecting shaft (9) is connected to one end of the main shaft (5) close to the liquid inlet; The inducer (2) is sleeved on the outside of the connecting shaft (9) and is connected to the connecting shaft (9).

5. The centrifugal pump self-ejection structure according to claim 1, characterized in that: The ejector (3) comprises a fixed ring (31) and a de-rotation plate (32); The anti-rotation plate (32) is connected to the outer side of the fixed ring (31); The fixed ring (31) is sleeved on the outer side of the inducer (2); The anti-rotation plate (32) is connected to the inner side of the housing (1); The jet channel (33) is provided between the fixed ring (31) and the housing (1).

6. The centrifugal pump self-ejection structure according to claim 4, characterized in that: The inducer (2) includes a hub (21) and a plurality of blades (22); A plurality of blades (22) are connected to the outer side of the hub (21) at intervals; The hub (21) is sleeved on the outside of the connecting shaft (9) and is connected to the connecting shaft (9); The ejector (3) is sleeved on the outside of the blade (22), and a blade tip gap (23) is provided between the ejector (3) and the blade (22) in the radial direction.

7. The centrifugal pump self-ejection structure according to claim 3, characterized in that: Also includes a bearing (10); The bearing (10) is arranged between the main shaft (5) and the machine cover (7).

8. The centrifugal pump self-ejection structure according to claim 1, characterized in that: Also included is a fixed blade cascade (11); The fixed blade grid (11) is connected to a channel of the casing (1) close to the liquid inlet.

9. The centrifugal pump self-ejection structure according to claim 1, characterized in that: The housing (1) further includes reinforcing ribs (12); The reinforcing ribs (12) are arranged on the outside of the housing (1).

10. The centrifugal pump self-ejection structure according to claim 1, characterized in that: An axial gap (34) is provided between the impeller (4) and the ejector (3) in the axial direction; A front chamber (13) is provided between the impeller (4) and the casing (1).

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