Tandem type plunger pump

Abstract

The utility model provides a tandem type plunger pump. The tandem type plunger pump comprises a pump body, a driving mechanism and plungers. The pump body is provided with a compression cavity and a driving cavity, and the part, located in the driving cavity, of the driving mechanism is connected with the plunger so as to drive the plunger to reciprocate in the compression cavity and the driving cavity; a sealing structure is arranged between the compression cavity and the driving cavity and is used for preventing grease in the driving cavity from entering the compression cavity; and an exhaust part is arranged on the sealing structure, communicates with the outside and is used for balancing the pressure difference in the driving cavity. The sealing structure is used for preventing grease in the driving cavity from entering the compression cavity; meanwhile, the exhaust part is arranged on the sealing structure, the driving cavity is communicated with the outside through the exhaust part, and the pressure difference generated in the driving cavity when the plunger moves in a reciprocating mode can be balanced, so that the influence of the pressure difference in the driving cavity on the movement of the plunger is avoided, and the driving efficiency of the plunger pump is guaranteed.

Description

Technical Field

[0001] This application relates to the field of plunger pump technology, specifically to a tandem plunger pump. Background Technology

[0002] A plunger pump is a type of pump that uses the reciprocating motion of a plunger within a pump cylinder to create a volume change between the plunger and the pump wall, repeatedly drawing in and discharging liquid and increasing its pressure. It relies on the reciprocating motion of the plunger within the cylinder to change the volume of the sealed working cavity, thereby achieving liquid suction and pressure transfer.

[0003] In existing plunger pumps, one end of the plunger is connected to the drive chamber, and the other end extends into the cylinder to reciprocate in the compression chamber to pressurize and draw in liquid. The drive chamber is filled with grease for lubrication. Therefore, a seal is formed between the drive chamber and the compression chamber to prevent grease from being carried into the compression chamber during the plunger's movement.

[0004] However, since the plunger is equipped with a corresponding sealing ring for sealing, the plunger will generate heat by friction with the sealing ring during reciprocating motion. The heat is difficult to dissipate and will affect the performance of the sealing ring or the pump body. On the other hand, due to the reciprocating motion of the plunger, a certain pressure difference will be generated in the drive chamber, causing the pressure in the drive chamber to be unbalanced, which will affect the reciprocating motion of the plunger and thus reduce the driving efficiency of the plunger pump.

[0005] Therefore, there is room for further improvement in the existing plunger pump technology. Utility Model Content

[0006] In view of this, and addressing the technical problem that the sealing structure between the drive chamber and the compression chamber in the prior art plunger pump causes a pressure difference in the drive chamber, affecting the driving efficiency of the plunger pump, this application provides a series plunger pump, in which an exhaust section is provided in the sealing structure, which can avoid the generation of a pressure difference in the drive chamber and ensure the driving efficiency of the plunger pump.

[0007] This application provides a tandem piston pump, including a pump body, a drive mechanism, and pistons;

[0008] The pump body is provided with a compression chamber and a drive chamber. The part of the drive mechanism located in the drive chamber is connected to the plunger to drive the plunger to reciprocate within the compression chamber and the drive chamber.

[0009] A sealing structure is provided between the compression chamber and the drive chamber, and the sealing structure is used to prevent grease in the drive chamber from entering the compression chamber;

[0010] The sealing structure is provided with an exhaust section, which is connected to the outside and is used to balance the pressure difference in the drive chamber.

[0011] Compared with the prior art, this application provides a series plunger pump, which has a sealing structure between the drive chamber and the compression chamber of the pump body to prevent grease in the drive chamber from entering the compression chamber; at the same time, an exhaust part is provided on the sealing structure, and the drive chamber is connected to the outside through the exhaust part, which can balance the pressure difference generated in the drive chamber when the plunger reciprocates, thereby avoiding the influence of the pressure difference in the drive chamber on the plunger movement and ensuring the driving efficiency of the plunger pump.

[0012] Preferably, the pump body is provided with a sealing cavity, and the compression cavity and the drive cavity are located at both ends of the sealing cavity;

[0013] The sealing structure is disposed within the sealing cavity.

[0014] Preferably, the exhaust section includes a first exhaust port and a second exhaust port;

[0015] The first vent is disposed at one end of the sealing cavity near the driving cavity, and the first vent is used to communicate the driving cavity with the sealing cavity;

[0016] The second vent is located at one end of the sealing cavity near the compression cavity, and the second vent is used to connect the sealing cavity to the outside.

[0017] Preferably, the pump body includes a radially disposed first end face, and the first exhaust port opens on the first end face;

[0018] The second vent hole opens on the circumferential sidewall of the pump body;

[0019] Wherein, the projection of the second exhaust hole on the first end face does not overlap with the first exhaust hole.

[0020] Preferably, the sealing structure includes a first sealing element and a second sealing element, wherein the first sealing element and the second sealing element are sleeved on the plunger;

[0021] The first seal is disposed at the end of the sealing cavity near the compression cavity, and the second seal is disposed at the end of the sealing cavity near the drive cavity;

[0022] The second vent is located between the first seal and the second seal.

[0023] Preferably, the sealing structure further includes a support member, which is sleeved on the plunger;

[0024] The support member is located between the first seal and the second seal, and the support member is used to axially limit the first seal and the second seal.

[0025] Preferably, the support member includes a support ring and support columns, and at least two support columns are provided, which are circumferentially spaced at the ends of the support ring;

[0026] The inner diameter of the circle formed by the support column is larger than the inner diameter of the support ring.

[0027] Preferably, the sealing cavity includes a first cavity and a second cavity, the first cavity being used to install the support member, and the second cavity being used to install the second sealing member;

[0028] Wherein, the inner diameter of the first cavity is larger than the inner diameter of the second cavity, and the outer diameter of the support member is smaller than the inner diameter of the first cavity.

[0029] Preferably, the second sealing element includes an inner ring and an outer ring, wherein the outer side of the inner ring is connected to the inner side of the outer ring;

[0030] The inner ring has at least one stop on its inner side;

[0031] The inner ring includes a first end, which protrudes toward the support member. The outer side of the first end is an inclined surface, and the inner side of the support column is in contact with the inclined surface.

[0032] Preferably, the pump body includes a first pump body and a second pump body, the first pump body and the second pump body are connected in series, the first pump body can output low-pressure liquid, and the second pump body can output high-pressure liquid;

[0033] The first pump body is provided with a main liquid inlet, and the second pump body is provided with a main liquid outlet.

[0034] The tandem piston pump disclosed in this application has at least the following technical advantages:

[0035] 1. By setting a sealing structure between the drive chamber and the compression chamber, it is possible to prevent grease in the drive chamber from entering the compression chamber. At the same time, an exhaust section is set on the sealing structure. The drive chamber is connected to the outside through the exhaust section, which can balance the pressure difference in the drive chamber and prevent the plunger from being obstructed due to the pressure difference in the drive chamber, thus ensuring the driving efficiency of the plunger pump.

[0036] 2. By setting up a sealing cavity, a space is created to house the two seals. The second exhaust port is placed between the two seals, which can effectively seal the compression cavity and also provide an effective pressure differential to the drive cavity.

[0037] 3. By setting a support between the two seals, the axial distance between the two seals can be limited, ensuring that the seals will not easily shift, thereby ensuring the sealing of the seals. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of a series plunger pump provided in an embodiment of this application;

[0039] Figure 2 This is a partial cross-sectional structural schematic diagram of a series plunger pump provided in an embodiment of this application;

[0040] Figure 3 This is a three-dimensional structural schematic diagram of a pump body provided in an embodiment of this application;

[0041] Figure 4 This is a partial three-dimensional cross-sectional structural diagram of a series plunger pump provided in an embodiment of this application;

[0042] Figure 5 yes Figure 2 A magnified view of part A;

[0043] Figure 6 yes Figure 3 A magnified view of part B;

[0044] Figure 7 This is a three-dimensional structural schematic diagram of a support ring provided in an embodiment of this application;

[0045] Figure 8 This is a three-dimensional cross-sectional structural diagram of the second sealing element provided in an embodiment of this application.

[0046] Reference numerals: 1. First pump body; 2. Second pump body; 3. First motor; 4. Second motor; 5. Plunger; 6. Main inlet; 7. Main outlet; 8. Drive chamber; 9. Compression chamber; 10. Sealing chamber; 11. First seal; 13. Second seal; 14. Support; 15. First end face; 16. First cavity; 17. Second cavity; 18. First vent; 19. Second vent; 20. Inner ring; 21. Outer ring; 22. First end; 23. Second end; 24. First stop; 25. Second stop; 26. Third stop; 27. Support ring; 28. Support column. Detailed Implementation

[0047] To enable those skilled in the art to better understand the technical solutions of this disclosure, the following detailed, clear, and complete description of this disclosure is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this disclosure and are not intended to limit it.

[0048] In the description of this application, the use of "first" and "second" is for the purpose of distinguishing technical features only, and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the order of the technical features indicated.

[0049] Those skilled in the art should understand that in the disclosure of this application, the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on this application.

[0050] The present application will now be described in further detail with reference to the accompanying drawings, see below. Figures 1 to 8 illustrate.

[0051] This application provides a tandem piston pump for pressurizing and outputting liquids; such as Figure 1 As shown, it includes a pump body and a drive mechanism. The pump body has a main inlet 6, a suction chamber and a main outlet 7. Atmospheric liquid enters the suction chamber through the main inlet 6, and the drive mechanism outputs power to control the liquid pressure in the suction chamber. Pressurized liquid flows out through the main outlet 7 to meet the liquid discharge requirements of different pressures.

[0052] Among them, such as Figure 2 As shown, the pump body is provided with a compression chamber 9 that communicates with the suction chamber and a drive chamber 8 for installing the drive mechanism. The drive mechanism is at least partially disposed in the drive chamber 8. The plunger 5 is located in both the compression chamber 9 and the drive chamber 8. One end of the plunger 5 is connected to the drive mechanism in the drive chamber 8, and the other end extends toward the compression chamber 9 and at least partially extends into the compression chamber 9. The drive mechanism provides power to drive the plunger 5 to reciprocate. By changing the volume of the plunger 5 in the compression chamber 9, liquid suction or pressurization is achieved.

[0053] In this application, a sealing structure is provided on the pump body. This sealing structure acts between the compression chamber 9 and the drive chamber 8, sealing the compression chamber 9 to prevent the plunger 5 from carrying grease from the drive chamber 8 into the compression chamber 9 during reciprocating motion; simultaneously, it also effectively prevents grease from escaping from the drive chamber 8. For example, Figure 2 , Figures 4 to 5 As shown, the sealing structure is provided with an exhaust section, and the drive chamber 8 is connected to the outside through the exhaust section. When the plunger 5 reciprocates in the drive chamber 8 and generates a pressure difference, the pressure difference in the drive chamber 8 can be balanced through the exhaust section, thereby preventing the plunger 5 from being obstructed due to the pressure difference in the drive chamber 8 and ensuring the driving efficiency of the plunger pump.

[0054] It should be noted that, in this application, if Figure 1As shown, the pump body includes a first pump body 1 and a second pump body 2. The drive mechanism includes a first motor 3 and a second motor 4. The first pump body 1 is connected to the first motor 3, and the second pump body 2 is connected to the second motor 4. A total inlet 6 is located on the first pump body 1, and a total outlet 7 is located on the second pump body 2. Liquid flows in from the total inlet 6 of the first pump body 1, then flows into the second pump body 2, and flows from the total outlet 7 of the second pump body 2 to the outlet pipe. The first pump body 1 is a low-pressure pump used to output low-pressure liquid; the second pump body 2 is a high-pressure pump used to output high-pressure liquid. That is, in this application, a sealing structure can be provided on either the first pump body 1 or the second pump body 2.

[0055] Specifically, the sealing structure will be further described; such as Figures 2 to 6 As shown, the pump body is provided with a sealing cavity 10, and the compression cavity 9 and the drive cavity 8 are located at both ends of the sealing cavity 10, respectively. The sealing cavity 10 is connected to the compression cavity 9 and the drive cavity 8. The end of the plunger 5 away from the drive mechanism passes through the drive cavity 8, the sealing cavity 10 and the compression cavity 9 in sequence. The sealing cavity 10 is a straight cylindrical structure, and the sealing structure is set inside the sealing cavity 10 to form corresponding seals for the compression cavity 9 and the drive cavity 8 at both ends.

[0056] Among them, such as Figure 3 and Figure 6 As shown, the exhaust section includes a first exhaust port 18 and a second exhaust port 19. The first exhaust port 18 is located at one end of the sealing cavity 10 near the driving cavity 8, and is used to communicate between the driving cavity 8 and the sealing cavity 10; wherein, as Figure 4 , Figure 6 As shown, a first end face 15 is radially arranged on the side of the pump body near the drive chamber 8, and a first exhaust port 18 is opened on the first end face 15 and extends through the first end face 15 axially.

[0057] like Figure 4 , Figure 6 As shown, the second vent 19 is located at one end of the sealing cavity 10 near the compression cavity 9. The second vent 19 opens on the circumferential sidewall of the pump body, that is, the second vent 19 penetrates the sidewall of the pump body radially. The second vent 19 is used to communicate the sealing cavity 10 with the outside. At least one first vent 18 and one second vent 19 are provided. In this embodiment, one first vent 18 is provided and two second vent 19 are provided, with the two vents spaced apart circumferentially along the sealing cavity 10.

[0058] In particular, the projection of the second vent hole 19 on the first end face 15 does not overlap with the first vent hole 18, thereby reducing the probability of grease entering the sealing cavity 10 from the first vent hole 18 and blocking the first vent hole 18, ensuring the stability of the pressure difference balance of the drive cavity 8, and further ensuring the driving stability of the plunger pump.

[0059] Correspondingly, such as Figure 2 , Figure 5 As shown, the sealing structure includes a first sealing element 11 and a second sealing element 13, which are sleeved on the plunger 5. The first sealing element 11 is disposed at the end of the sealing cavity 10 near the compression cavity 9, wherein the first sealing element 11 is at least partially located in the compression cavity 9 and at least partially located in the sealing cavity 10. The first sealing element 11 is used to seal between the compression cavity 9 and the sealing cavity 10. The second sealing element 13 is disposed at the end of the sealing cavity 10 near the drive cavity 8, and the second sealing element 13 is used to block the drive cavity 8, which can effectively prevent most of the grease in the drive cavity 8 from entering the sealing cavity 10.

[0060] Among them, such as Figure 4 As shown, the second exhaust port 19 is located between the first seal 11 and the second seal 13, which can ensure that the gas flows into the sealing cavity 10 from the second exhaust port 19 and then enters the driving cavity 8 from the sealing cavity 10 to balance the pressure difference, and ensure that the compression cavity 9 is not connected to the outside, thus ensuring the effective sealing of the compression cavity 9.

[0061] Furthermore, such as Figure 4 , Figure 5 As shown, the sealing structure also includes a support member 14, which is sleeved on the plunger 5 and located between the first seal 11 and the second seal 13. The end face of the support member 14 near the first seal 11 is in contact with the first seal 11, and the end face of the support member 14 near the second seal 13 is in contact with the second seal 13. The support member 14 is used to limit the axial distance between the first seal 11 and the second seal 13, ensuring that the two seals will not move and become misaligned under the friction of the plunger 5, thereby ensuring the sealing performance of the seals.

[0062] Specifically, such as Figure 7 As shown, the support member 14 includes a support ring 27 and support columns 28. The support ring 27 is an annular structure with a certain width in the radial direction. At least two support columns 28 are provided. The support columns 28 are plate-shaped structures and are circumferentially spaced on the end face of the support ring 27 facing the second seal 13, and are equidistant from each other. The radial width of the support column 28 is smaller than the radial width of the support ring 27. The inner diameter of the support ring 27 is almost the same as the outer diameter of the plunger 5. The support ring 27 is used for fixing so that the support member 14 can be stably connected to the plunger 5.

[0063] Among them, such as Figure 5As shown, the inner diameter of the circumference formed by the support column 28 is larger than the inner diameter of the support ring 27, so that there is a gap between the inner wall of the support column 28 and the outer wall of the plunger 5. While ensuring the structural strength of the support member 14, the contact area between the support member 14 and the plunger 5 is reduced. When the plunger 5 is in operation, the plunger 5 generates heat through friction with the seal. Since there is a space between the support column 28 and the plunger 5, it can play a certain role in heat dissipation, preventing the plunger 5 from overheating and affecting the performance of other components.

[0064] Furthermore, such as Figure 5 , Figure 7 As shown, the axial thickness of the inner ring of the support ring 27 is smaller than that of the outer ring, which can reduce the contact area between the inner ring of the support ring 27 and the plunger 5 and assist in heat dissipation.

[0065] Based on any of the above embodiments, the second sealing element 13 can be further extended; such as... Figure 5 , Figure 8 As shown, the second sealing element 13 includes an inner ring 20 and an outer ring 21. The inner ring 20 and the outer ring 21 are coaxially arranged. The outer side of the inner ring 20 is connected to the inner side of the outer ring 21. The outer side of the inner ring 20 is provided with a radial connecting ring. The inner ring 20 is connected to the outer ring 21 through the radial connecting ring so that there is a radial gap between the inner ring 20 and the outer ring 21.

[0066] Among them, such as Figure 8 As shown, the end of the connecting ring facing the first seal 11 is flush with the end of the outer ring 21; the inner ring 20 includes a first end 22 and a second end 23, the first end 22 being close to the first seal 11, and the second end 23 being close to the second seal 13, wherein the first end 22 protrudes beyond the end of the outer ring 21 in the direction of the support member 14, wherein the outer surface of the first end 22 is an inclined surface, and the outer diameter of the first end 22 near the second seal 13 is larger than the outer diameter near the first seal 11; as shown Figure 5 As shown, the end of the support column 28 facing the second seal 13 acts on the inclined surface, that is, the inner diameter of the circumference formed by the support column 28 is smaller than the outer diameter of the end of the first end 22 near the first seal 11, so that the inner side of the support column 28 fits against the inclined surface; by setting the inclined surface, the support column 28 can overlap the second seal 13, forming a radial limit on the second seal 13, preventing the second seal 13 from separating from the plunger 5; and it can also ensure the structural strength and effective sealing of the second seal 13.

[0067] Furthermore, such as Figure 5 , Figure 8As shown, the inner ring 20 has at least one stop on its inner side, and the stop has a triangular cross-section. In this embodiment, the inner ring 20 has three stops on its inner side, namely a first stop 24, a second stop 25, and a third stop 26. The first stop 24 is located at the first end 22, and the second stop 25 and the third stop 26 are located at the second end 23. The second stop 25 is located between the first stop 24 and the third stop 26, and the three stops have different inner diameters. The third stop 26 has the smallest inner diameter, and the inner diameter of the third stop 26 is smaller than the outer diameter of the plunger 5. It has better sealing performance with the plunger 5 and can reduce the probability of grease in the drive chamber 8 entering between the second seal 13 and the piston.

[0068] In addition, such as Figure 4 As shown, the first vent hole 18 is located between the second seal 13 and the drive cavity 8. In the radial direction, the distance between the inner side of the first vent hole 18 and the axis of the sealing cavity 10 is less than the distance between the outer ring 21 and the axis of the sealing cavity 10. This ensures that if grease in the drive cavity 8 flows into the sealing cavity 10 through the first vent hole 18, most of it will enter the space between the second seal 13 and the drive cavity 8, effectively preventing the grease from moving across the second seal 13 towards the first seal 11 and avoiding grease blockage of the second vent hole 19.

[0069] Correspondingly, such as Figure 5 As shown, the sealing cavity 10 includes a first cavity 16 and a second cavity 17. The first cavity 16 is mainly used to install the support member 14, that is, the support member 14 is basically located inside the first cavity 16, wherein the outer diameter of the support member 14 is smaller than the inner diameter of the first cavity 16. The second cavity 17 is used to install the second sealing member 13, and the outer diameter of the second sealing member 13 is basically the same as the inner diameter of the second cavity 17. Moreover, the inner diameter of the first cavity 16 is larger than the inner diameter of the second cavity 17, which makes the space inside the second cavity 17 larger, increasing the heat dissipation space at the support member 14 and effectively assisting the plunger 5 in heat dissipation.

[0070] In actual use, if a pressure difference is generated in the drive chamber 8 during the reciprocating movement of the plunger 5, the plunger 5 will rub against the second seal 13, causing the second seal 13 to move slightly. However, since the support 14 axially limits the second seal 13 and radially limits the inner ring 20 of the second seal 13, the inner ring 20 will not move easily, but the outer ring 21 will move slightly. Therefore, a gap is generated between the outer ring 21 and the sealing chamber 10, and the drive chamber 8 is temporarily connected to the outside through the first exhaust port 18 and the second exhaust port 19. This balances the pressure difference in the drive chamber 8, ensures the smooth movement of the plunger 5, and ensures the driving efficiency of the plunger pump.

[0071] It should be noted that the various embodiments of this application can be arbitrarily combined into new embodiments, provided that the solutions do not conflict and the technical solutions can coexist.

[0072] The present application has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present application. The descriptions of the embodiments above are only for the purpose of helping to understand the present application and its core ideas. It should be noted that those skilled in the art can make several improvements and modifications to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A tandem plunger pump, characterized in that, Includes pump body, drive mechanism and plunger (5); The pump body is provided with a compression chamber (9) and a drive chamber (8). The part of the drive mechanism located in the drive chamber (8) is connected to the plunger (5) to drive the plunger (5) to reciprocate within the compression chamber (9) and the drive chamber (8). A sealing structure is provided between the compression chamber (9) and the drive chamber (8), and the sealing structure is used to prevent grease in the drive chamber (8) from entering the compression chamber (9); The sealing structure is provided with an exhaust section, which is connected to the outside and is used to balance the pressure difference inside the drive chamber (8).

2. The tandem plunger pump according to claim 1, characterized in that, The pump body is provided with a sealing cavity (10), and the compression cavity (9) and the drive cavity (8) are located at both ends of the sealing cavity (10); The sealing structure is disposed within the sealing cavity (10).

3. The tandem plunger pump according to claim 2, characterized in that, The exhaust section includes a first exhaust port (18) and a second exhaust port (19). The first vent (18) is disposed at one end of the sealing cavity (10) near the driving cavity (8), and the first vent (18) is used to connect the driving cavity (8) and the sealing cavity (10); The second vent (19) is located at one end of the sealing cavity (10) near the compression cavity (9), and the second vent (19) is used to connect the sealing cavity (10) to the outside.

4. The tandem plunger pump according to claim 3, characterized in that, The pump body includes a radially arranged first end face (15), and the first exhaust port (18) is open on the first end face (15); The second exhaust port (19) is opened on the circumferential side wall of the pump body; The projection of the second exhaust hole (19) onto the first end face (15) does not overlap with the first exhaust hole (18).

5. The tandem plunger pump according to claim 3, characterized in that, The sealing structure includes a first sealing element (11) and a second sealing element (13), which are fitted onto the plunger (5); The first seal (11) is disposed at the end of the sealing cavity (10) near the compression cavity (9), and the second seal (13) is disposed at the end of the sealing cavity (10) near the drive cavity (8); The second vent (19) is located between the first seal (11) and the second seal (13).

6. The tandem piston pump according to claim 5, characterized in that, The sealing structure also includes a support member (14), which is sleeved on the plunger (5); The support member (14) is located between the first seal (11) and the second seal (13), and the support member (14) is used to axially limit the first seal (11) and the second seal (13).

7. The tandem plunger pump according to claim 6, characterized in that, The support member (14) includes a support ring (27) and support columns (28), wherein at least two support columns (28) are provided, and the support columns (28) are circumferentially spaced at the ends of the support ring (27); The inner diameter of the circle formed by the support column (28) is larger than the inner diameter of the support ring (27).

8. The tandem plunger pump according to claim 6, characterized in that, The sealing cavity (10) includes a first cavity (16) and a second cavity (17), the first cavity (16) being used to install the support member (14), and the second cavity (17) being used to install the second sealing member (13). Wherein, the inner diameter of the first cavity (16) is greater than the inner diameter of the second cavity (17), and the outer diameter of the support member (14) is smaller than the inner diameter of the first cavity (16).

9. The tandem plunger pump according to claim 7, characterized in that, The second seal (13) includes an inner ring (20) and an outer ring (21), wherein the outer side of the inner ring (20) is connected to the inner side of the outer ring (21); The inner ring (20) has at least one stop on its inner side; The inner ring (20) includes a first end (22), which protrudes toward the support member (14). The outer side of the first end (22) is an inclined surface, and the inner side of the support column (28) is in contact with the inclined surface.

10. The tandem plunger pump according to claim 1, characterized in that, The pump body includes a first pump body (1) and a second pump body (2), the first pump body (1) and the second pump body (2) are connected in series, the first pump body (1) can output low-pressure liquid, and the second pump body (2) can output high-pressure liquid; The first pump body (1) is provided with a main liquid inlet (6), and the second pump body (2) is provided with a main liquid outlet (7).

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