A submersible reverse drive single-cylinder single-suction double-discharge reciprocating piston pump

Abstract

The present invention relates to a submersible reverse-drive single-cylinder single-suction double-displacement reciprocating plunger pump, belonging to the field of pump technology. The pump comprises a pump body, a reciprocating drive mechanism, and a plunger; the reciprocating drive mechanism drives the plunger via a transmission rod; the plunger chamber comprises a large-diameter chamber and a small-diameter chamber constituting a liquid discharge chamber, and the lower end portion of the small-diameter chamber is a plunger hole structure; the plunger comprises a small-diameter plunger portion and a large-diameter plunger portion, and the outer diameter of the small-diameter plunger portion is larger than the outer diameter of the transmission rod; the large-diameter plunger portion is sealed with a gap between the large-diameter chamber and the large-diameter chamber, thereby dividing the large-diameter chamber into a liquid inlet chamber and a transfer chamber; a liquid discharge channel and a liquid inlet channel are provided on the plunger, respectively used to connect the small-diameter chamber with the transfer chamber, and to connect the liquid inlet chamber with the transfer chamber; a liquid discharge check valve is arranged on the liquid discharge channel, and a liquid suction check valve is arranged on the liquid inlet channel. The pump discharges solution medium during both the up and down strokes of the plunger, thereby improving the balance of the equipment, and can be used in fields such as oil extraction.

Description

Technical Field

[0001] The present invention relates to the technical field of pumps, in particular to a submersible reverse-driven single-cylinder single-suction double-displacement reciprocating plunger pump. Background Art

[0002] In fields such as oil production, it is necessary to use an oil well pump to pump underground oil and other solution media to the surface; the specific structure of the oil well pump is usually constructed using a plunger pump, for example, an axial plunger pump with publication number CN110578663A is used for construction, mainly based on the advantages of the axial plunger pump such as compact structure, good process, small size, light weight and high discharge pressure.

[0003] The pump body structure of the plunger pump can be specifically Figure 1 and Figure 2 The pump body structure 01 shown is constructed, and the pump body structure 01 includes a pump body 02 provided with a plunger chamber 020, a plunger 04 installed in the plunger chamber 020 so as to be axially reciprocating, and a reciprocating drive mechanism located on the ground; for the reciprocating drive mechanism, a kowtow machine arranged on the ground is usually used for construction.

[0004] To drive the plunger 04 of the underground plunger pump, the reciprocating drive mechanism requires a drive rod 05 extending into the plunger chamber 020 to drive the plunger 04 to move back and forth vertically. In this embodiment, a fitting connection hole 043 is provided on the plunger 04 for fitting with the drive rod 05. Other specific connection methods can also be used for fixed connection.

[0005] like Figure 1 and Figure 2 As shown, the plunger 04 during movement will separate the plunger chamber 020 into a liquid inlet chamber 021 and a liquid discharge chamber 022, and the liquid inlet chamber 021 is connected to the outside through a liquid inlet hole 023 provided on the pump body 02, while the liquid discharge chamber 022 is connected to the outside through a liquid discharge hole provided on the pump body 02; an upper liquid discharge channel 042 and a lower liquid discharge channel 041 arranged vertically are arranged inside the plunger, and the upper liquid discharge channel 042 and the lower liquid discharge channel 041 constitute a liquid discharge channel 040 for connecting the liquid inlet chamber 021 and the liquid discharge chamber 022; a non-return one-way valve 032 for discharge is provided in the liquid discharge channel 040 for preventing the solution medium from flowing back from the liquid discharge chamber 022 to the liquid inlet chamber 021; and a non-return one-way valve 031 for suction is provided on the liquid inlet hole 023 for preventing the solution medium from flowing back from the liquid inlet chamber 021 to the outside.

[0006] During use, when the reciprocating drive mechanism drives the plunger 04 upward via the transmission rod 05, negative pressure is generated in the liquid inlet chamber 021, opening the one-way valve 031 for liquid suction, allowing external petroleum or other liquid medium to enter the liquid inlet chamber 021 through the liquid inlet hole 023. Furthermore, the upward movement of the plunger 04 compresses the volume of the discharge chamber 022, closing the one-way valve 032 and closing the discharge channel 040, allowing the liquid in the discharge chamber 022 to be discharged to the outside through the discharge hole. This allows the underground petroleum or other liquid medium to be pumped to the surface. However, during use, there are the following problems: using a reciprocating drive mechanism arranged from above will result in a larger land occupation area and increase investment costs; the most important problem is that during use, petroleum is only discharged during the upward movement, resulting in uneven power distribution of the drive mechanism, which leads to large driving force pulsation. Furthermore, contact between the transmission rod and the oil rod will cause eccentric wear, which reduces the service life of the equipment.

[0007] In order to solve the above problems, a submersible reverse-driven plunger pump is usually used and equipped with four one-way ball valves as check valves. However, due to the limitations of the product structure and size, the layout is extremely difficult, the workmanship is poor, and there are many failures. Summary of the Invention

[0008] The main purpose of the present invention is to provide a submersible reverse-drive reciprocating piston pump that can achieve a double-discharge function based on a single-cylinder single-suction system during use, thereby effectively improving the power balance of the drive equipment and better realizing the layout of the submersible reverse drive.

[0009] Another object of the present invention is to provide a submersible reverse-driven single-cylinder single-suction double-discharge reciprocating piston pump, so that during use, it can achieve the purpose of approximately double equal discharge based on single-cylinder single-suction.

[0010] In order to achieve the above-mentioned main purpose, the reciprocating plunger pump provided by the present invention is a submersible reverse-drive single-cylinder single-suction double-row plunger pump; the plunger pump includes a pump body provided with a plunger chamber, a reciprocating drive mechanism and a plunger which can be vertically moved in the plunger chamber; the reciprocating drive mechanism is located on the lower side of the pump body, and drives the plunger to move back and forth based on the transmission rod; the transmission rod passes through the through hole provided on the pump body in a liquid-tight manner; from bottom to top, the plunger chamber includes a large-diameter chamber and a small-diameter chamber constituting a discharge chamber; the small-diameter chamber is connected to the outside through a discharge hole provided on the pump body, and the small-diameter chamber includes a section of a plunger hole structure; the plunger includes a small-diameter plunger part and a large-diameter plunger part which are arranged up and down and solidly connected, and the outer diameter of the small-diameter plunger part is larger than the outer diameter of the transmission rod; the small-diameter plunger The large-diameter plunger part is in sealing cooperation with the clearance of the plunger hole structure, and the small-diameter chamber is liquid-sealed; the large-diameter plunger part is in sealing cooperation with the clearance of the large-diameter chamber; from top to bottom, the large-diameter plunger part moves to separate the large-diameter chamber into a liquid inlet chamber part and a transfer chamber part with variable volume; the liquid inlet chamber part is connected with the outside through the liquid inlet hole provided on the pump body; a liquid inlet channel and a lower liquid discharge channel part arranged vertically are provided inside the large-diameter plunger part, and an upper liquid discharge channel part is provided on the small-diameter plunger part; the upper liquid discharge channel and the lower liquid discharge channel are connected to form a liquid discharge channel for connecting the small-diameter chamber and the transfer chamber part; the liquid inlet channel is used to connect the liquid inlet chamber part and the transfer chamber part; a one-way valve for liquid discharge for non-return is arranged on the liquid discharge channel, and a one-way valve for liquid suction for non-return is arranged on the liquid inlet channel.

[0011] In the above technical solution, the structure of the internal plunger chamber of the pump body and the structure of the plunger are improved, mainly by arranging the plunger chamber to include a large-diameter chamber and a small-diameter chamber that are interconnected, and correspondingly setting the plunger to a small-diameter plunger part and a large-diameter plunger part that are fixedly connected, and arranging a drainage channel and a liquid inlet channel inside the plunger; so that during operation, when the reciprocating drive mechanism drives the plunger upward through the transmission rod, the non-return function of the one-way valve for drainage closes the drainage channel, thereby generating a negative pressure in the transfer chamber and opening the one-way valve for suction, opening the liquid inlet channel, and thereby sucking petroleum and other solution media into the transfer chamber; at the same time, because the small-diameter plunger part occupies part of the small-diameter chamber, the solution medium is discharged from the drainage hole. When the reciprocating drive mechanism drives the plunger downward through the transmission rod, the one-way valve for liquid discharge is opened to open the liquid discharge channel, and the one-way valve for liquid suction is cut off to close the liquid inlet channel. Since the small-diameter plunger part withdraws from part of the small-diameter chamber, the solution medium enters the liquid discharge chamber from the transfer chamber, and since the outer diameter of the small-diameter plunger part is larger than the outer diameter of the transmission rod, the volume of the solution medium entering the liquid discharge chamber is larger than the new volume of the liquid discharge chamber due to the withdrawal of the small-diameter plunger part, so that part of the solution medium is discharged from the liquid discharge hole, so that the solution medium is discharged from the liquid discharge hole in both the upward and downward strokes of the plunger. Therefore, during use, the double-row function is realized based on the single-cylinder single-suction, thereby effectively improving the power balance of the driving equipment and better realizing the layout of the submersible reverse drive.

[0012] The specific solution is that the pump body includes a small-diameter cavity for enclosing a small-diameter chamber, and a large-diameter cavity for enclosing a large-diameter chamber; the upper port of the large-diameter chamber is an open structure; the small-diameter cavity and the large-diameter cavity are connected to each other, so that the large-diameter chamber and the small-diameter chamber are connected.

[0013] A more specific solution is that the lower end portion of the small-diameter cavity is liquid-tightly sleeved inside the upper end portion.

[0014] The preferred solution is that the drainage hole is arranged on the top of the pump body.

[0015] The preferred solution is that the multiple liquid inlet holes are evenly distributed along the circumference of the pump body.

[0016] The preferred solution is that the pump body is a cylindrical structure, and both the small-diameter chamber and the large-diameter chamber are circular cavity structures.

[0017] A preferred solution is that the small-diameter chamber includes a housing cavity located adjacent to and above the plunger hole structure; the lower end of the small-diameter chamber is a plunger hole structure that seals against the small-diameter plunger; and on a plane perpendicular to the vertical axis, the projection of the housing cavity wall lies outside the projection of the plunger hole structure, with a difference of at least a predetermined distance. This technical solution facilitates the machining of the pump body structure in which the small-diameter chamber is located.

[0018] In order to achieve the above-mentioned other purpose, the preferred solution provided by the present invention is that in the process of the plunger moving upward by a unit distance relative to the pump body, the ratio of the suction volume to the discharge volume is 1.9 to 2.1; the suction volume is the volume of the solution medium sucked into the transfer chamber during the upward movement of the plunger; the discharge volume is the volume of the solution medium discharged from the small-diameter chamber during the upward movement of the plunger.

[0019] In the above technical solution, based on the preset structure and size ratio of the plunger and the transmission rod, the ratio of the liquid absorption volume to the liquid discharge volume is 1.9 to 2.1, thereby roughly achieving double equal discharge in the upward and downward strokes of the plunger, that is, the volume of the solution medium discharged in the two strokes is roughly the same.

[0020] A further solution is that the ratio of the suction volume to the discharge volume is 2.

[0021] In order to achieve the other purpose mentioned above, the preferred solution provided by the present invention is that the dimensions of the plunger and the transmission rod satisfy the ratio of the first value to the second value of 1.95 to 2.05; the first value is the difference between the square of the radius of the large-diameter plunger and the square of the radius of the transmission rod, and the second value is the square of the radius of the small-diameter plunger.

[0022] In the above technical solution, based on the preset structure and size ratio of the plunger and the transmission rod, double equal discharge in the upward and downward strokes of the plunger is roughly achieved, that is, the volume of the solution medium discharged in the two strokes is roughly the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural diagram of an existing plunger pump;

[0024] Figure 2 for Figure 1 Schematic diagram of the plunger structure of the plunger pump shown;

[0025] Figure 3 Schematic diagram of the structure of the plunger pump in an embodiment of the present invention;

[0026] Figure 4 Schematic diagram of the structure of the plunger in an embodiment of the present invention;

[0027] Figure 5 Schematic diagram of the structure of the plunger in an embodiment of the present invention;

[0028] Figure 6 Schematic diagram of the structure of the plunger and the transmission rod in an embodiment of the present invention;

[0029] Figure 7 This is a structural diagram of the plunger's downward movement in an embodiment of the present invention;

[0030] Figure 8 Schematic diagram of the structure of the upward movement of the plunger in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the embodiments and the accompanying drawings.

[0032] The main concept of the present invention is to improve the structure of the existing plunger pump to construct a submersible reverse-drive single-cylinder single-suction double-displacement reciprocating plunger pump. Therefore, in the process of pumping a solution medium such as crude oil, the solution medium can be pumped based on one and a half strokes in one reciprocating stroke, and the solution medium is discharged during the entire reciprocating stroke, thereby improving the driving balance of the drive device. Based on this main concept, the structure and shape of the pump body are not limited to the schematic structure in the following embodiments. For example, a non-circular cross-sectional structure can be adopted, the number and structural dimensions of the discharge channels and the liquid inlet channels are configured according to actual needs, and the small-diameter cavity and the large-diameter cavity in the cavity structure are arranged, processed and connected according to actual needs.

[0033] Example

[0034] See also Figures 3 to 8The reciprocating plunger pump 1 of the present invention is a submersible reverse-driven single-cylinder single-suction double-discharge type, that is, a single suction based on a single plunger can achieve the discharge of the solution medium throughout the entire process. Structurally, the reciprocating plunger pump 1 includes a pump body 2 provided with a plunger chamber 9, a reciprocating drive mechanism not shown in the figure, and a plunger 3 vertically movably placed in the plunger chamber 9. In this embodiment, the main structures of the plunger 4, the plunger chamber 9 and the pump body 2 are all cylindrical structures, and can also be set to other shapes according to actual needs. In addition, the specific structure of the reciprocating drive mechanism can be designed with reference to existing products, for example, the reciprocating drive mechanism disclosed in the patent document with publication number CN110578663A can be used.

[0035] In order to construct a submersible reverse drive structure, the reciprocating drive mechanism is configured to be located on the lower side of the pump body 2, that is, vertically located below the pump body 2, so that it can enter the ground together with the pump body 2 during use, thereby effectively reducing the occupation of the ground source. At this time, if the solution medium can be discharged throughout the entire process based on a single cylinder and single suction, the underground arrangement of the reciprocating drive mechanism can be well realized. In this technical solution, this embodiment drives the plunger 3 to move back and forth vertically through the transmission rod 11. Specifically, the transmission rod 11 passes through the through hole provided on the pump body 2 and enters the plunger chamber 9 of the pump body 2 from the outside, and by arranging a sealing device 42 and a sealing device mounting bracket 41 on the pump body, a liquid-tight through hole is set up to achieve a sealing setting between the transmission rod 11 and the pump body 2. As Figure 4 and Figure 5 As shown, in order to facilitate the connection between the transmission rod 11 and the plunger 3, a rod fitting hole 53 for fittingly connecting the upper end of the transmission rod 11 is provided on the lower end of the plunger.

[0036] Regarding the specific structure of the plunger chamber 9, as shown in FIG. Figures 3 to 8 As shown, from bottom to top, the plunger chamber 9 includes a large-diameter chamber 20 and a small-diameter chamber 70 that are connected to each other. The small-diameter chamber 70 constitutes the drainage chamber in this embodiment, and the small-diameter chamber 70 is connected to the outside through a drainage hole 71 provided on the pump body 2, thereby discharging a solution medium such as crude oil and cement slurry from the plunger chamber 9. In this embodiment, in order to facilitate the gap sealing cooperation between the small-diameter chamber 70 and the plunger 3 and achieve a liquid sealing effect, the lower end portion of the small-diameter chamber 70 is provided with a plunger hole structure 701; it can also be provided with a plunger hole structure 701 in the middle area or the upper section according to actual needs to meet the drainage requirements.

[0037] For the specific structure of the plunger 3, as shown in FIG. Figures 3 to 8As shown, corresponding to the large and small diameter vertical distribution structure of the plunger chamber 9, the plunger 3 includes a large-diameter plunger portion 5 and a small-diameter plunger portion 6, which are solidly connected. The outer diameter of the small-diameter plunger portion 6 is larger than the outer diameter of the transmission rod 11, so that the solution medium can be discharged from the drainage hole 71 throughout the entire stroke. During operation, the small-diameter plunger portion 6 is sealed with the gap between the lower end of the small-diameter chamber 70 constituting the plunger hole structure 701, and the lower end of the small-diameter chamber 70 is liquid-sealed, thereby isolating the large-diameter chamber 20 from the small-diameter chamber 70, preventing the solution medium such as crude oil from directly flowing between the large-diameter chamber 20 and the small-diameter chamber 70, thereby affecting the pumping effect. During operation, the large-diameter plunger portion 5 and the large-diameter chamber 20 are sealed and matched. The large-diameter plunger portion 5 moves in a top-down direction, dividing the large-diameter chamber 20 into a liquid inlet chamber 201 and a transfer chamber 202, the volume of which is variable as the large-diameter plunger portion 5 moves. The liquid inlet chamber 201 is directly connected to the outside through a liquid inlet hole 21 provided on the pump body 2. That is, a solution medium such as crude oil enters the plunger chamber 20, specifically, enters the interior of the liquid inlet chamber 201, through the liquid inlet hole 21 under the action of pressure. In this embodiment, the structural dimensions, number, and specific position of the liquid inlet hole 21 and the liquid discharge hole 71 can be configured according to actual needs. In this embodiment, the liquid discharge hole 71 is arranged on the top of the pump body 2, and the plurality of liquid inlet holes 21 are evenly distributed along the circumference of the pump body 2.

[0038] In order to realize the transportation of a solution medium such as crude oil to the small-diameter chamber 70 constituting the drainage chamber through the transfer chamber 202, a liquid inlet channel 51 and a lower liquid discharge channel portion 52 are arranged inside the large-diameter plunger portion 5, and an upper liquid discharge channel portion 61 is provided on the small-diameter plunger portion 6; the specific structures of the liquid inlet channel 51, the lower liquid discharge channel portion 52 and the upper liquid discharge channel portion 61 can be constructed using a channel structure directly formed inside the plunger structure, or can be constructed using a pipeline arranged inside it. The upper drainage channel 61 and the lower drainage channel 52 are directly connected to form the drainage channel 8 in this embodiment, which is used to connect the small-diameter chamber 70 and the transfer chamber 202; the liquid inlet channel 51 is used to connect the liquid inlet chamber 201 and the transfer chamber 202; in order to avoid the backflow problem of the solution medium during the transportation process, a one-way valve 44 for drainage is arranged on the drainage channel 8, and a one-way valve 43 for suction is arranged on the liquid inlet channel 51. In this embodiment, the one-way valve 44 for drainage and the one-way valve 43 for suction are both constructed with one-way valves, and the specific structure refers to the existing product design; in order to facilitate the arrangement of the above-mentioned two one-way valves for non-return, in this embodiment, both are arranged on the channel located inside the large-diameter plunger 5.

[0039] In order to better construct the above-mentioned layout structure of large and small diameter chambers and save pump body construction materials, in this embodiment, the pump body 2 specifically includes a small diameter cavity 7 for enclosing a small diameter chamber 70, and a large diameter cavity 29 for enclosing a large diameter chamber 20. In order to facilitate the connection of the two cavity structures, the upper end portion of the large diameter chamber 20 is set as an open structure; and the small diameter cavity 7 is docked with the large diameter cavity 29, so that the large diameter chamber 20 and the small diameter chamber 70 are connected. In this embodiment, the lower end portion of the small diameter cavity 7 is liquid-tightly sleeved within the upper end portion of the large diameter chamber 20, that is, the connection is made using a sleeve structure, which is easy to manufacture and seal. The specific structure of the pump body 2 can be arranged in an equal-sized structure, or it can be constructed in an integral structure instead of the above-mentioned segmented splicing structure.

[0040] As described above, in this embodiment, the pump body 2 is configured as a cylindrical structure, so that the small-diameter chamber 70 , the large-diameter chamber 20 and the plunger 3 are all configured as cylindrical structures.

[0041] like Figure 7 As shown, in order to facilitate the manufacture of the small-diameter cavity 7, in this embodiment, the small-diameter chamber 70 is configured to include a accommodating cavity portion 702 and a lower port portion which is a plunger hole structure 701, and the accommodating cavity portion 702 is located on the adjacent upper side of the plunger hole structure 701; and on a plane perpendicular to the vertical direction, the cavity wall projections of the accommodating cavity portion 702 are all located outside the projection of the plunger hole structure 702, and the difference is greater than a predetermined distance, that is, during the upward movement of the small-diameter plunger 6, the distance between it and the inner wall surface of the accommodating cavity portion 702 is greater than the distance between it and the inner wall of the plunger hole structure 702, thereby storing part of the solution medium; specifically, the accommodating cavity portion 702 is located in the plunger hole structure 701, both of which are cylindrical cavity structures, and the central axes of the two are arranged collinearly, and the radius of the accommodating cavity portion 702 is greater than the radius of the plunger hole structure 701.

[0042] Based on Figures 3 to 8 The structure shown in the figure, the working process of this reciprocating piston pump is as follows:

[0043] (1) Figure 7As shown, when the reciprocating drive mechanism drives the plunger 3 to move down the stroke L2 through the transmission rod 11, due to the pressure of the solution medium such as crude oil, the discharge one-way valve 44 is opened to open the discharge channel 8, and the suction one-way valve 43 is closed to close the liquid inlet channel 51. In this process, the small-diameter plunger portion 6 withdraws from part of the small-diameter chamber 70, and the large-diameter plunger portion 5 occupies part of the transfer chamber 202, so that the crude oil and other solution medium sealed in the transfer chamber 202 is pressed from the transfer chamber 202 into the discharge cavity, that is, into the vacant small-diameter chamber 70. In addition, since the outer diameter of the small-diameter plunger portion 6 is larger than the outer diameter of the transmission rod 11 in terms of structural dimensions, the volume of the solution medium entering the discharge cavity is larger than the new volume of the discharge cavity due to the withdrawal of the small-diameter plunger portion 6, so that part of the solution medium is discharged from the discharge hole 71, and thus the solution medium is discharged from the discharge hole 71 during the downward movement of the plunger.

[0044] (2) Figure 8 As shown, when the reciprocating drive mechanism drives the plunger 3 to move up the stroke L2 through the transmission rod 11, due to the pressure of the solution medium such as crude oil, the non-return function of the one-way valve 44 for discharge closes the discharge channel 8, thereby generating a negative pressure in the transfer chamber 202 and causing the one-way valve 43 for suction to open, thereby opening the liquid inlet channel 51, thereby sucking the solution medium such as crude oil into the transfer chamber 202; at the same time, because the small-diameter plunger portion 6 occupies part of the small-diameter chamber 70, the solution medium is discharged from the discharge hole 71, and thus the solution medium is discharged from the discharge hole 71 during the upward movement of the plunger.

[0045] From the description of the above working process, it can be seen that during use, the solution medium is discharged from the drainage hole 71 in both the upward and downward strokes of the plunger 3, that is, this embodiment realizes the double-row function based on single-cylinder single suction, thereby effectively improving the power balance of the driving equipment, so as to better realize the layout of the submersible reverse drive.

[0046] Preferably, in order to achieve approximately equal discharge flow throughout the entire process, that is, a roughly double-equal discharge effect, in this embodiment, the structural dimensions of the plunger 3 and the transmission rod 11 are configured so that in the process of the plunger 3 moving upward by a unit distance relative to the pump body 2, the ratio of the suction volume to the discharge volume is 1.9 to 2.1, and preferably the ratio of the suction volume to the discharge volume is 2; wherein the suction volume is configured as the volume of the solution medium inside the transfer chamber 202 during the process, and the discharge volume is the volume of the solution medium discharged from the small-diameter chamber 70 during this upward movement.

[0047] In order to achieve the above-mentioned roughly double-even row effect, in this embodiment, for the cylindrical plunger 3 and the plunger chamber 20, the structural dimensions of the plunger 3 and the transmission rod 11 can be configured to satisfy the ratio of the first value to the second value of 1.95 to 2.05; wherein the first value is configured as the difference between the square of the radius of the large-diameter plunger 5 and the square of the radius of the transmission rod 11, and the second value is configured as the square of the radius of the small-diameter plunger 6, and the radii here are both outer diameters.

[0048] According to the above description, it can be seen that during the working process, the driving motor of the reciprocating drive mechanism is always in a working state, so its power in one stroke will be smaller than the power of the unidirectional oil pump. As the ratio of the suction volume to the discharge volume is close to 2, the power of the driving motor of the reciprocating drive mechanism is roughly half of that of the unidirectional oil pump, which can effectively reduce the requirements for the equipment.

Claims

1. A submersible reverse-drive single-cylinder single-suction double-displacement reciprocating plunger pump, comprising a pump body provided with a plunger chamber, a reciprocating drive mechanism, and a plunger vertically movably disposed within the plunger chamber; the reciprocating drive mechanism is located on the lower side of the pump body and drives the plunger to reciprocate based on a drive rod; the drive rod passes through a through hole provided in the pump body in a liquid-tight manner; from bottom to top, the plunger chamber comprises a large-diameter chamber and a small-diameter chamber constituting a liquid discharge chamber; the small-diameter chamber communicates with the exterior via a liquid discharge hole provided in the pump body, and the small-diameter chamber includes a segmented portion having a plunger hole structure; and is characterized in that: The plunger includes a small-diameter plunger portion and a large-diameter plunger portion arranged vertically and solidly connected, and the outer diameter of the small-diameter plunger portion is larger than the outer diameter of the transmission rod; the small-diameter plunger portion is in sealing cooperation with the plunger hole structure to liquid-seal the small-diameter chamber; the large-diameter plunger portion is in sealing cooperation with the large-diameter chamber, and the large-diameter plunger portion moves from top to bottom to separate the large-diameter chamber into a liquid inlet chamber and a transfer chamber with variable volume; the liquid inlet chamber is connected to the outside through a liquid inlet hole provided on the pump body; A liquid inlet channel and a lower liquid discharge channel portion are vertically arranged inside the large-diameter plunger portion, and an upper liquid discharge channel portion is provided on the small-diameter plunger portion; the upper liquid discharge channel and the lower liquid discharge channel are connected to form a liquid discharge channel for connecting the small-diameter chamber and the transfer chamber portion; the liquid inlet channel is used to connect the liquid inlet chamber portion and the transfer chamber portion; a one-way valve for liquid discharge is arranged on the liquid discharge channel, and a one-way valve for liquid suction is arranged on the liquid inlet channel; The pump body includes a small-diameter cavity for enclosing the small-diameter cavity, and a large-diameter cavity for enclosing the large-diameter cavity; the upper port portion of the large-diameter cavity is an open structure; the small-diameter cavity is docked with the large-diameter cavity, so that the large-diameter cavity and the small-diameter cavity are connected.

2. The submersible reverse drive single-cylinder single-suction double-displacement reciprocating plunger pump according to claim 1, characterized in that: The lower end portion of the small-diameter cavity is fluid-tightly sleeved inside the upper end portion.

3. The submersible reverse drive single-cylinder single-suction double-displacement reciprocating piston pump according to claim 1 or 2, characterized in that: The drainage hole is arranged on the top of the pump body.

4. The submersible reverse drive single-cylinder single-suction double-displacement reciprocating plunger pump according to claim 3, characterized in that: The small-diameter chamber includes an accommodating cavity portion, and the accommodating cavity portion is located adjacent to the upper side of the plunger hole structure; the lower end portion of the small-diameter chamber is the plunger hole structure; On a plane perpendicular to the vertical direction, projections of the cavity walls of the accommodating cavity are all located outside the projections of the plunger hole structure and are separated by a predetermined distance.

5. The submersible reverse drive single-cylinder single-suction double-displacement reciprocating piston pump according to claim 3, characterized in that: During the upward movement of the plunger relative to the pump body by a unit distance, the ratio of the suction volume to the discharge volume is 1.9 to 2.1; the suction volume is the volume of the solution medium sucked into the transfer chamber during the upward movement of the plunger; The liquid discharge volume is the volume of the solution medium discharged from the small-diameter chamber during the upward movement of the plunger.

6. The submersible reverse drive single-cylinder single-suction double-displacement reciprocating piston pump according to claim 3, characterized in that: The dimensions of the plunger and the transmission rod satisfy a ratio of a first value to a second value of 1.95 to 2.05; the first value is the difference between the square of the radius of the large-diameter plunger and the square of the radius of the transmission rod, and the second value is the square of the radius of the small-diameter plunger.

7. The submersible reverse drive single-cylinder single-suction double-displacement reciprocating piston pump according to claim 1 or 2, characterized in that: The plurality of liquid inlet holes are evenly distributed along the circumference of the pump body.

8. The submersible reverse drive single-cylinder single-suction double-displacement reciprocating piston pump according to claim 1 or 2, characterized in that: The pump body is a cylindrical structure, and both the small-diameter chamber and the large-diameter chamber are circular cavity structures.

9. The submersible reverse drive single-cylinder single-suction double-displacement reciprocating plunger pump according to claim 1 or 2, characterized in that: The small-diameter chamber includes an accommodating cavity portion, and the accommodating cavity portion is located adjacent to the upper side of the plunger hole structure; the lower end portion of the small-diameter chamber is the plunger hole structure; On a plane perpendicular to the vertical direction, projections of the cavity walls of the accommodating cavity are all located outside the projections of the plunger hole structure and are separated by a predetermined distance.

10. The submersible reverse drive single-cylinder single-suction double-displacement reciprocating piston pump according to claim 1 or 2, characterized in that: During the upward movement of the plunger relative to the pump body by a unit distance, the ratio of the suction volume to the discharge volume is 1.9 to 2.1; the suction volume is the volume of the solution medium sucked into the transfer chamber during the upward movement of the plunger; The liquid discharge volume is the volume of the solution medium discharged from the small-diameter chamber during the upward movement of the plunger.

11. The submersible reverse drive single-cylinder single-suction double-displacement reciprocating piston pump according to claim 10, characterized in that: The ratio of the suction volume to the discharge volume is 2.

12. The submersible reverse drive single-cylinder single-suction double-displacement reciprocating piston pump according to claim 1 or 2, characterized in that: The dimensions of the plunger and the transmission rod satisfy a ratio of a first value to a second value of 1.95 to 2.05; the first value is the difference between the square of the radius of the large-diameter plunger and the square of the radius of the transmission rod, and the second value is the square of the radius of the small-diameter plunger.

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