Graded drainage structure of multi-stage safety injection pump
By designing a multi-stage hierarchical drainage structure on the pump cylinder of a multi-stage low-voltage insufficiency of the nuclear power plant, the problems of low efficiency and incompleteness of the traditional drainage structure are solved, and more efficient and thorough wastewater discharge is achieved, reducing maintenance risks.
Patent Information
- Application Number
- CN202420741552.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-10
- Publication Date
- 2025-03-18
- Estimated Expiration
- 2034-04-10
AI Technical Summary
The drainage structure of the multi-stage low-voltage insufficiency pump in traditional nuclear power plants is single, resulting in low drainage efficiency and the inability to completely discharge wastewater from the pump body, increasing the difficulty and risk of subsequent maintenance work.
A multi-stage staging drainage structure is designed. By setting up multiple drainage holes and drainage pipe groups on the pump cylinder, and setting up inner holes and collection tanks at the suction section and the multi-stage middle section, the staging discharge of wastewater is achieved.
It improves the efficiency of water discharge in the pump, ensures that the wastewater discharge in the pump body is more thorough, reduces the probability of wastewater residue, and reduces the risk and difficulty of subsequent maintenance or maintenance.
Smart Images
Figure CN222633436U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of nuclear power pumps, in particular to a multi-stage injection pump graded drainage structure. Background Art
[0002] Traditional nuclear power plant multi-stage low-pressure injection pumps usually have only one drainage port, and the water in the pump is discharged from this location. This method not only has low drainage efficiency, but also easily leads to incomplete drainage and water remaining in the pump body. If more water with radioactive media remains in the pump, it will increase the difficulty of subsequent maintenance work and increase the risk. Utility Model Content
[0003] The purpose of the utility model is to provide a multi-stage injection pump graded drainage structure, which can improve the efficiency of water discharge in the pump, and the water in the pump body is discharged more thoroughly, with less waste water remaining in the pump body, reducing the difficulty of subsequent detection work and reducing the risk of maintenance operations.
[0004] The embodiment of the utility model is achieved as follows:
[0005] In a first aspect, the utility model provides a multi-stage injection pump graded drainage structure, comprising:
[0006] A pump barrel, a central shaft, a suction section, a multi-stage impeller and a multi-stage middle section, wherein the central shaft is rotatably mounted on the pump barrel, and the multi-stage impellers are all sleeved outside the central shaft; the multi-stage middle sections are connected in sequence, and the suction section is connected to the first-stage middle section of the multi-stage middle sections; the pump barrel has a suction chamber corresponding to the suction section and an outlet chamber corresponding to the last-stage impeller of the multi-stage impeller, the suction chamber is provided with a first drainage pipe group, and the outlet chamber is provided with a second drainage pipe group.
[0007] In an optional embodiment, a suction inner hole is provided through the outer wall of the suction section, and the suction inner hole connects the area enclosed by the suction section and the suction chamber; a first drainage hole is provided through the wall of the pump cylinder, and the first drainage hole connects the suction inner hole; and the first drainage pipe group is connected to the first drainage hole.
[0008] Based on the above scheme, wastewater in the area surrounded by the suction section can enter the first drainage hole from the suction inner hole, and then enter the first drainage pipe group from the first drainage hole, and be discharged through the first drainage pipe group, which is convenient for drainage.
[0009] In an optional embodiment, a first collecting groove is provided on the inner circumferential surface of the pump cylinder, and the suction inner hole and the first drainage hole are both connected to the first collecting groove.
[0010] Based on the above scheme, the water in the area surrounded by the suction section first enters the first collecting tank from the suction inner hole, and the waste water is collected to enter the first drainage pipe group from the first drainage hole, so the drainage efficiency is high.
[0011] In an optional embodiment, a second drainage hole is provided through the cylinder wall of the pump cylinder, and the second drainage pipe group is connected to the second drainage hole.
[0012] Based on the above solution, the waste water in the outlet cavity directly enters the second drainage hole, then enters the second drainage pipe group from the second drainage hole, and is discharged through the second drainage pipe group, so that the waste water is easily discharged.
[0013] In an optional embodiment, a first-stage inner hole is provided on the first-stage middle section, a third drainage hole is provided on the pump barrel, the first-stage inner hole is connected to the third drainage hole, and a third drainage pipe group is provided at the third drainage hole.
[0014] Based on the above scheme, the wastewater in the area enclosed by the middle section of the first stage can enter the inner hole of the first stage, enter the third drainage hole from the inner hole of the first stage, and then be discharged from the third drainage pipe group. The wastewater in the area enclosed by the middle section of the first stage can not only be discharged from the outlet mouth, but also from the inner hole of the first stage. The wastewater discharge efficiency is high, and it is not easy for wastewater to remain in the area enclosed by the middle section of the first stage.
[0015] In an optional embodiment, a second collecting groove is provided on the inner circumferential surface of the pump cylinder, and the first-stage inner hole and the third drainage hole are both connected to the second collecting groove.
[0016] Based on the above solution, due to the design of the second collecting trough, the drainage area is increased, and the wastewater discharge efficiency in the area surrounded by the middle section of the first stage is high.
[0017] In an optional embodiment, a secondary inner hole is provided on the secondary middle section of the multi-stage middle section, a fourth drainage hole is provided on the pump barrel, the secondary inner hole is connected to the fourth drainage hole, and a fourth drainage pipe group is provided at the fourth drainage hole.
[0018] Based on the above scheme, the wastewater in the area enclosed by the secondary middle section can enter the secondary inner hole, enter the fourth drainage hole from the secondary inner hole, and then be discharged from the fourth drainage pipe group. The wastewater in the area enclosed by the secondary middle section can not only be discharged from the outlet mouth, but also be discharged from the secondary inner hole. The wastewater discharge efficiency is high, and it is not easy for wastewater to remain in the area enclosed by the secondary middle section.
[0019] In an optional embodiment, the axis of the secondary inner hole is arranged at an acute angle with the axis of the central axis, and the height of the orifice of the secondary inner hole close to the suction section is lower than the height of the other orifice of the secondary inner hole.
[0020] Based on the above scheme, the design of the secondary inner hole is more reasonable, which not only meets the discharge of wastewater from the secondary inner hole, but also ensures that the structural strength of the secondary middle section is not affected, and the secondary middle section is safe and reliable to use.
[0021] In an optional embodiment, the multi-stage injection pump graded drainage structure also includes a pump cover connected to the pump barrel and an end cover connected to the pump cover, the end cover and the pump cover cooperate to define an outer cavity, and the outer cavity is provided with a fifth drainage pipe group.
[0022] Based on the above scheme, during the operation of the injection pump, part of the wastewater inside the pump barrel will enter the outer cavity through the gap between the balance drum and the balance sleeve arranged at the center axis, resulting in the presence of wastewater in the outer cavity. Through the design of the fifth drain pipe group, the wastewater in the outer cavity can be discharged from the fifth drain pipe group, thereby reducing the probability of wastewater remaining in the outer cavity, which is beneficial to subsequent maintenance operations.
[0023] In an optional embodiment, the first drain pipe group or the second drain pipe group includes a drain pipe fixedly connected to the pump cylinder and a valve installed on the drain pipe.
[0024] Based on the above scheme, the first drainage pipe group or the second drainage pipe group has a simple structure and is easy to assemble. By controlling the valve, it is convenient to adjust the operating state of the drainage pipe and is not likely to affect the normal operation of the injection pump.
[0025] The beneficial effects of the embodiments of the utility model are:
[0026] In summary, the multi-stage injection pump graded drainage structure provided in this embodiment can allow external water to be sucked into the pump body when the injection pump is operating normally, and then be discharged from the water outlet on the pump barrel after flowing along the set path. When the injection pump is finished running, it is necessary to discharge the wastewater inside the injection pump, which not only avoids the impact of the wastewater on the service life of the injection pump, but also reduces the risk of subsequent inspection or maintenance of the injection pump. At this time, open the first drain pipe group and the second drain pipe group, and the wastewater in the pump barrel can be discharged from the first drain pipe group and the second drain pipe group at the same time, with a large drainage area and high drainage efficiency, and reduces the probability of wastewater remaining in the pump, so that drainage is more thorough, and subsequent maintenance or inspection of the injection pump is not easily affected by the residual internal wastewater, which reduces the difficulty of operation and reduces the risk of operation. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.
[0028] Figure 1 It is a structural schematic diagram of a multi-stage injection pump graded drainage structure according to an embodiment of the utility model;
[0029] Figure 2 It is a schematic structural diagram of the first drainage pipe group according to an embodiment of the utility model.
[0030] icon:
[0031] 100-pump barrel; 101-first drain hole; 102-second drain hole; 103-third drain hole; 104-fourth drain hole; 105-first collecting tank; 106-second collecting tank; 200-central axis; 300-suction section; 310-suction inner hole; 400-multi-stage impeller; 500-first stage middle section; 501-first stage inner hole; 510-secondary stage middle section; 511-secondary inner hole; 600-balance drum; 610-balance sleeve; 700-pump cover; 701-fifth drain hole; 800-end cover; 801-external cavity; 900-first drain pipe group; 901-drain pipe; 902-valve; 910-second drain pipe group; 920-third drain pipe group; 930-fourth drain pipe group; 940-fifth drain pipe group. DETAILED DESCRIPTION
[0032] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.
[0033] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0034] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.
[0035] In the description of the present utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, or the orientation or position relationship in which the utility model product is usually placed when in use, which is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.
[0036] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.
[0037] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" 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 it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0038] In the prior art, a multi-stage injection pump is only provided with a drainage structure at the outlet. When the injection pump is running, the drainage structure at the outlet is opened to discharge the wastewater in the pump. Due to the single drainage structure, there are problems such as low drainage efficiency and incomplete drainage, which results in wastewater remaining in the pump, increasing the difficulty of maintenance work and the risk of maintenance.
[0039] In view of this, the designer provides a multi-stage injection pump graded drainage structure, which improves the drainage efficiency by increasing the drainage area, reduces the probability of wastewater remaining in the pump body, and discharges the wastewater more thoroughly.
[0040] Please combine Figure 1In this embodiment, the graded drainage structure of the multi-stage injection pump includes a pump barrel 100, a central shaft 200, a suction section 300, a multi-stage impeller 400 and a multi-stage middle section. The central shaft 200 is rotatably mounted on the pump barrel 100, and the multi-stage impellers 400 are all sleeved outside the central shaft 200; the multi-stage middle sections are connected in sequence, and the suction section 300 is connected to the first-stage middle section 500 in the multi-stage middle sections; the pump barrel 100 has a suction chamber corresponding to the suction section 300 and an outlet chamber corresponding to the last-stage impeller in the multi-stage impeller 400, the suction chamber is provided with a first drainage pipe group 900, and the outlet chamber is provided with a second drainage pipe group 910.
[0041] Based on the above, the working principle of the multi-stage injection pump graded drainage structure provided in this embodiment is as follows:
[0042] During operation, close the first drain pipe group 900 and the second drain pipe group 910 to avoid affecting the normal operation of the injection pump. During the operation of the injection pump, external water can be sucked into the pump body from the water inlet on the pump barrel 100, and discharged from the water outlet on the pump barrel 100 after flowing along the set path. When the injection pump is finished running, it is necessary to discharge the wastewater inside the injection pump, which not only avoids the impact of wastewater on the service life of the injection pump, but also reduces the risk of subsequent inspection or maintenance of the injection pump. At this time, open the first drain pipe group 900 and the second drain pipe group 910, and the wastewater in the pump barrel 100 can be discharged from the first drain pipe group 900 and the second drain pipe group 910 at the same time, with a large drainage area and high drainage efficiency, and reduces the probability of wastewater remaining in the pump, and the drainage is more thorough. Subsequent maintenance or overhaul of the injection pump is not easily affected by the residual wastewater inside, reducing the difficulty of operation and reducing the risk of operation.
[0043] The following embodiments illustrate the details of the multi-stage injection pump graded drainage structure provided by the present application by way of examples.
[0044] Please combine Figure 1 In this embodiment, the graded drainage structure of the multi-stage injection pump includes a pump barrel 100, a central shaft 200, a suction section 300, a multi-stage impeller 400, a multi-stage middle section, a balance drum 600, a balance sleeve 610, a pump cover 700, an end cover 800, a first drainage pipe group 900, a second drainage pipe group 910, a third drainage pipe group 920, a fourth drainage pipe group 930 and a fifth drainage pipe group 940.
[0045] The pump cover 700 cooperates with the pump barrel 100, and the end cover 800 cooperates with the pump cover 700, and the pump cover 700 and the end cover 800 define an outer cavity 801. The central shaft 200 is disposed in the pump barrel 100 and rotatably cooperates with the pump barrel 100 through a bearing. At the same time, the central shaft 200 passes through the pump cover 700 and the end cover 800. The balance drum 600 is sleeved on the outside of the central shaft 200 and rotates with the central shaft 200. The balance sleeve 610 is sleeved on the outside of the balance drum 600. The balance sleeve 610 is fixedly connected to the pump cover 700. There is an annular gap between the balance sleeve 610 and the balance drum 600. The chamber surrounded by the pump barrel 100 is connected to the outer cavity 801 through the annular gap, that is, the wastewater in the area surrounded by the pump barrel 100 will enter the outer cavity 801 through the annular gap.
[0046] The multi-stage impellers 400 are all fixed on the central shaft 200 and arranged in sequence in the axial direction of the central shaft 200, and the multi-stage impellers 400 rotate with the central shaft 200. For example, in this embodiment, the impeller is provided with three stages. The multi-stage middle sections are all arranged in the pump barrel 100, and the multi-stage middle sections are fixedly connected in sequence. For example, in this embodiment, when the impeller is three-stage, the middle section is two-stage, namely, the first-stage middle section 500 corresponding to the first-stage impeller and the secondary middle section 510 corresponding to the secondary impeller. The suction section 300 is fixedly connected to the side of the first-stage middle section 500 away from the secondary middle section 510.
[0047] The first drain pipe group 900, the second drain pipe group 910, the third drain pipe group 920 and the fourth drain pipe group 930 are all connected to the pump barrel 100. The first drain pipe group 900 is used to discharge waste water corresponding to the suction section 300, the second drain pipe group 910 is used to discharge waste water corresponding to the outlet cavity, that is, the final impeller, the third drain pipe group 920 is used to discharge waste water corresponding to the primary middle section 500, and the fourth drain pipe group 930 is used to discharge waste water corresponding to the secondary middle section 510. The fifth drain pipe group 940 is installed on the pump cover 700 and is used to discharge waste water corresponding to the outer cavity 801.
[0048] With such a design, the wastewater in the injection pump can be discharged through the first drain pipe group 900, the second drain pipe group 910, the third drain pipe group 920, the fourth drain pipe group 930 and the fifth drain pipe group 940. The wastewater discharge efficiency is high and less wastewater remains in the pump body, which is beneficial to the subsequent maintenance work of the injection pump and can improve the safety of the maintenance work.
[0049] Optionally, the first drain hole 101, the second drain hole 102, the third drain hole 103 and the fourth drain hole 104 are provided on the cylinder wall of the pump cylinder 100, and the first collecting groove 105 and the second collecting groove 106 are provided on the inner wall surface of the pump cylinder 100, the first drain hole 101 is connected to the first collecting groove 105; the third drain hole 103 is connected to the second collecting groove 106. The first drain pipe group 900 is connected to the first drain hole 101, the second drain pipe group 910 is connected to the second drain hole 102, the third drain pipe group 920 is connected to the third drain hole 103, the fourth drain pipe group 930 is connected to the fourth drain hole 104, and the fourth drain hole 104 is connected to the outer cavity 801.
[0050] Optionally, a fifth drainage hole 701 is provided on the pump cover 700 , and the fifth drainage pipe set 940 is connected to the fifth drainage hole 701 .
[0051] Optionally, the outer wall of the suction section 300 is penetrated with a suction inner hole 310, and the two ends of the suction inner hole 310 are respectively connected to the area surrounded by the suction section 300 and the first collection tank 105, and the wastewater at the suction section 300 enters the first collection tank 105 from the suction inner hole 310, and then enters the first drainage pipe group 900 from the first collection tank 105, and is discharged from the first drainage pipe group 900. Due to the design of the first collection tank 105, the wastewater is concentrated in the first collection tank 105 and discharged, and the discharge efficiency is high.
[0052] Similarly, the first-stage middle section 500 is provided with a first-stage inner hole 501, one end of which is connected to the area surrounded by the first-stage middle section 500 and the second collecting tank 106. Wastewater in the area surrounded by the first-stage middle section 500 enters the second collecting tank 106 from the first-stage inner hole 501, and then enters the second drainage pipe group 910 from the second collecting tank 106 and is discharged. Since the second collecting tank 106 has the function of collecting wastewater, the wastewater discharge efficiency is improved.
[0053] The secondary middle section 510 is provided with a secondary inner hole 511, the axis of the secondary inner hole 511 and the axis of the central axis 200 form an acute angle, the height of the opening of the secondary inner hole 511 close to the suction section 300 is lower than the height of the other opening of the secondary inner hole 511, the secondary inner hole 511 is directly connected to the fourth drainage hole 104, and the waste water in the rest of the area surrounded by the secondary middle section 510 enters the fourth drainage hole 104 from the secondary inner hole 511, and then is discharged through the fourth drainage pipe group 930. Since the secondary inner hole 511 is inclined, the machinable area of the secondary middle section 510 is reasonably utilized, and the drainage efficiency is improved while ensuring the structural strength of the secondary middle section 510.
[0054] Please combine Figure 1 and Figure 2In this embodiment, optionally, the structures of the first drain pipe group 900, the second drain pipe group 910, the third drain pipe group 920, the fourth drain pipe group 930 and the fifth drain pipe group 940 can be set to be the same. For example, the first drain pipe group 900 is taken as an example for description. The first drain pipe group 900 includes a drain pipe 901 and a valve 902. The drain pipe 901 can be a metal pipe. The drain pipe 901 is welded to the pump barrel 100, and the port of the drain pipe 901 is connected to the first drain hole 101. The valve 902 is installed on the drain pipe 901, and the valve 902 can control the on and off of the drain pipe 901 and adjust the flow rate. It should be understood that the drain pipe 901 of the fifth drain pipe group 940 is welded to the pump cover 700.
[0055] Furthermore, the valve 902 may be, but is not limited to, a regulating valve.
[0056] The multi-stage injection pump graded drainage structure provided in this embodiment has the following advantages: when the injection pump has finished running, the first drainage pipe group 900, the second drainage pipe group 910, the third drainage pipe group 920, the fourth drainage pipe group 930 and the fifth drainage pipe group 940 are opened, and the waste water of the pump body can be discharged from the first drainage pipe group 900, the second drainage pipe group 910, the third drainage pipe group 920, the fourth drainage pipe group 930 and the fifth drainage pipe group 940 respectively. The drainage efficiency is high, the drainage is more thorough, the difficulty of subsequent maintenance work is reduced, and the safety of the maintenance work is improved.
[0057] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.
Claims
1. A multi-stage injection pump graded drainage structure, characterized in that: include: A pump barrel (100), a central shaft (200), a suction section (300), a multi-stage impeller (400) and a multi-stage middle section, wherein the central shaft (200) is rotatably mounted on the pump barrel (100), and the multi-stage impeller (400) is sleeved outside the central shaft (200); the multi-stage middle sections are connected in sequence, and the suction section (300) is connected to the first-stage middle section (500) of the multi-stage middle sections; the pump barrel (100) has a suction chamber corresponding to the suction section (300) and an outlet chamber corresponding to the last-stage impeller of the multi-stage impeller (400), the suction chamber is provided with a first drainage pipe group (900), and the outlet chamber is provided with a second drainage pipe group (910).
2. The multi-stage injection pump graded drainage structure according to claim 1 is characterized in that: The outer wall of the suction section (300) is penetrated by a suction inner hole (310), and the suction inner hole (310) is connected to the area surrounded by the suction section (300) and the suction chamber; the cylinder wall of the pump cylinder (100) is penetrated by a first drainage hole (101), and the first drainage hole (101) is connected to the suction inner hole (310); the first drainage pipe group (900) is connected to the first drainage hole (101).
3. The multi-stage injection pump graded drainage structure according to claim 2 is characterized in that: The inner circumferential surface of the pump barrel (100) is provided with a first collecting groove (105), and the suction inner hole (310) and the first drainage hole (101) are both connected to the first collecting groove (105).
4. The multi-stage injection pump graded drainage structure according to claim 1 is characterized in that: A second drainage hole (102) is provided through the wall of the pump cylinder (100), and the second drainage pipe group (910) is connected to the second drainage hole (102).
5. The multi-stage injection pump graded drainage structure according to claim 1 is characterized in that: The first-stage middle section (500) is provided with a first-stage inner hole (501), the pump barrel (100) is provided with a third drainage hole (103), the first-stage inner hole (501) is connected to the third drainage hole (103), and a third drainage pipe group (920) is provided at the third drainage hole (103).
6. The multi-stage injection pump graded drainage structure according to claim 5 is characterized in that: A second collecting groove (106) is provided on the inner circumferential surface of the pump barrel (100), and the first-stage inner hole (501) and the third drainage hole (103) are both connected to the second collecting groove (106).
7. The multi-stage injection pump graded drainage structure according to claim 1 is characterized in that: A secondary inner hole (511) is provided on the secondary middle section (510) in the multi-stage middle section, a fourth drainage hole (104) is provided on the pump barrel (100), the secondary inner hole (511) is connected to the fourth drainage hole (104), and a fourth drainage pipe group (930) is provided at the fourth drainage hole (104).
8. The multi-stage injection pump graded drainage structure according to claim 7 is characterized in that: The axis of the secondary inner hole (511) is arranged at an acute angle with the axis of the central axis (200), and the height of the orifice of the secondary inner hole (511) close to the suction section (300) is lower than the height of the other orifice of the secondary inner hole (511).
9. The multi-stage injection pump graded drainage structure according to claim 1, characterized in that: The multi-stage injection pump graded drainage structure also includes a pump cover (700) connected to the pump barrel (100) and an end cover (800) connected to the pump cover (700), wherein the end cover (800) cooperates with the pump cover (700) to define an outer cavity (801), and the outer cavity (801) is provided with a fifth drainage pipe group (940).
10. The multi-stage injection pump graded drainage structure according to claim 1, characterized in that: The first drainage pipe set (900) or the second drainage pipe set (910) comprises a drainage pipe (901) fixedly connected to the pump barrel (100) and a valve (902) installed on the drainage pipe (901).