Automatic return deep-sea plunger pump suction and discharge structure and plunger pump

Abstract

The present invention relates to an automatic return deep-sea plunger pump suction and discharge structure and a plunger pump, comprising a cylinder body, a stepped plunger cavity is arranged in the cylinder body, the stepped plunger cavity comprises a first plunger cavity, a connecting cavity and a second plunger cavity which are coaxially and sequentially arranged, a plunger is slidably arranged in the stepped plunger cavity, the plunger comprises a first plunger part which cooperates with the first plunger cavity and a second plunger part which cooperates with the second plunger cavity, a connecting plunger part which passes through the connecting cavity is arranged between the first plunger part and the second plunger part, a first sealing member is arranged between the connecting plunger part and the connecting cavity, a ball head is arranged at the end of the second plunger part which extends out of the cylinder body, the first plunger cavity connects a suction channel and a discharge channel, the cross-sectional area of ​​the first plunger part is greater than the cross-sectional area of ​​the second plunger part, and the difference between the cross-sectional area of ​​the first plunger part and the cross-sectional area of ​​the second plunger part is greater than a set value, the suction and discharge structure of the present invention has a simple structure and a long service life.

Description

Technical Field

[0001] The invention relates to the technical field of plunger pumps, and in particular to an automatic return deep-sea plunger pump suction and discharge structure and a plunger pump. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] As a key basic component of seawater hydraulic system, deep-sea plunger pump is the key research object in seawater hydraulic transmission technology. Among various structural forms of hydraulic pumps, plunger pump works best, so most of the existing plunger pumps are swash plate axial plunger type. Swash plate axial piston pump works by using the volume change and pressure change caused by the reciprocating motion of the plunger in the plunger hole in the cylinder. When working, the driving spindle drives the swash plate to rotate, and then drives the plunger to reciprocate. Every time the driving spindle rotates one circle, the plunger performs a round of reciprocating motion, and the plunger pump performs a suction and discharge of liquid.

[0004] Compared with the working condition of the plunger pump in the air, in the deep sea environment, one end of the plunger of the plunger pump suction and discharge mechanism is in a high-pressure seawater environment, and the other end is in the plunger cavity. The pressure in the plunger cavity changes periodically between negative pressure and high pressure. Since the plunger cavity is in a negative pressure state when the plunger returns, the ambient pressure is much higher than the plunger cavity pressure. Under the action of the pressure difference, a huge force will be generated to hinder the return of the plunger. Therefore, a return mechanism is required to provide a return force to complete the return action of the plunger. The return mechanisms of the commonly used plunger pump suction and discharge mechanisms are as follows:

[0005] (1) Center spring return: The center spring is used to compress the return disk, thereby driving the plunger to return. However, in deep sea environments, the spring is difficult to provide such a large return force and cannot solve the return problem.

[0006] (2) Clearance return: This method fixes the swash plate and the return plate, thereby limiting the sliding shoe between the swash plate and the return plate and retaining a certain gap. However, when the return force is large, a large pulling force will be generated on the return plate, requiring a complex return assembly, and the return plate is prone to fatigue damage under the action of alternating loads.

[0007] (3) Use spring return for each small plunger, and use the spring force to press the plunger onto the swash plate. On the one hand, the spring is difficult to provide the required return force, and on the other hand, the high-frequency expansion and contraction of the spring can easily cause fatigue damage to the spring.

[0008] (4) Auxiliary pump oil supply return: In this method, the pressure generated by the auxiliary pump to replenish oil is always pressed on the return plate, but it is difficult to achieve in deep sea environment. The system is complex and heavy, which reduces the maneuverability of the submersible.

[0009] At present, the return mechanism of deep-sea plunger pumps often adopts the gap return method, which has a complex structure, and the return plate is easily fatigued and damaged under the action of alternating loads. In addition, the friction and wear between the return plate and the sliding shoe are serious, which greatly reduces the working stability and life of the plunger pump. Summary of the invention

[0010] In view of the deficiencies in the prior art, the purpose of the present invention is to provide an automatic return deep-sea plunger pump suction and discharge structure and a plunger pump, which have a simple structure, good working stability and a long service life.

[0011] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0012] In a first aspect, an embodiment of the present invention provides an automatic return deep-sea plunger pump suction and discharge structure, including a cylinder body, a stepped plunger cavity is provided in the cylinder body, the stepped plunger cavity includes a first plunger cavity, a connecting cavity and a second plunger cavity which are coaxially and sequentially arranged, a plunger is slidably provided in the stepped plunger cavity, the plunger includes a first plunger portion which cooperates with the first plunger cavity and a second plunger portion which cooperates with the second plunger cavity, a connecting plunger portion which passes through the connecting cavity is provided between the first plunger portion and the second plunger portion, a first sealing member is provided between the connecting plunger portion and the connecting cavity, a ball head is provided at the end of the second plunger portion extending out of the cylinder body, the first plunger cavity connects a suction channel and a discharge channel, the cross-sectional area of ​​the first plunger portion is greater than the cross-sectional area of ​​the second plunger portion, and the difference between the cross-sectional area of ​​the first plunger portion and the cross-sectional area of ​​the second plunger portion is greater than a set value;

[0013] The set value is the ratio of the product of the set negative pressure value, the force-bearing area of ​​the inner end surface of the second plunger part and the ambient pressure.

[0014] Optionally, a first guide cavity is provided on the side of the first plunger cavity away from the connecting cavity, the diameter of the first guide cavity is larger than the diameter of the first plunger cavity, one end of the first guide cavity is coaxially connected to the first plunger cavity, and the other end extends to the end face of the cylinder body, and a first guide sleeve is provided between the cavity surface of the first guide cavity and the first plunger part, and the first guide sleeve is slidably matched with the first plunger part.

[0015] Optionally, one end of the first guide sleeve contacts a first guide end cover fixed to the outer end surface of the cylinder body, and the other side is provided with a second seal, and the first guide sleeve presses the second seal onto a step surface formed between the first plunger cavity and the first guide cavity.

[0016] Optionally, a second guide cavity is provided on the side of the second plunger cavity away from the connecting cavity, the diameter of the second guide cavity is larger than the diameter of the second plunger cavity, one end of the second guide cavity is connected to the second plunger cavity, and the other end extends to the end surface of the cylinder body, and a second guide sleeve is provided between the cavity surface of the second guide cavity and the second plunger part, and the second guide sleeve is slidably matched with the second plunger part.

[0017] Optionally, one end of the second guide sleeve contacts a second guide cover fixed on the outer end surface of the cylinder body, and the other side is provided with a third seal, and the second guide sleeve presses the third seal onto a step surface formed between the second plunger cavity and the second guide cavity.

[0018] Optionally, the first plunger cavity is connected to a balancing channel arranged in the cylinder body, one end of the balancing channel is connected to the first plunger cavity, and the other end is provided with a plug, the balancing channel is connected to one end of the connecting channel, and the other end of the connecting channel is connected to the liquid inlet channel.

[0019] Optionally, a liquid inlet one-way valve is provided at the liquid inlet channel so that liquid in the liquid inlet channel can only flow into the second plunger chamber from outside the cylinder body, and a liquid discharge channel is provided with a liquid discharge one-way valve so that liquid in the liquid discharge channel can only flow from the second plunger chamber to outside the cylinder body.

[0020] Optionally, the second plunger part is integrally connected to the connecting plunger part, one end of the connecting plunger part is connected to the second plunger part, and the other end is provided with an internal threaded hole, and the end of the first plunger part used for connecting the connecting plunger part is provided with an external threaded shaft section, and the external threaded shaft section is threadedly connected to the internal threaded hole to connect the first plunger part, the connecting plunger part and the second plunger part into a whole;

[0021] or

[0022] The first plunger portion, the second plunger portion and the connecting plunger portion are integrally connected.

[0023] Optionally, a connecting portion is provided between the end of the second plunger portion extending outside the cylinder body and the ball head, and a diameter of the connecting portion is smaller than a diameter of the second plunger portion.

[0024] In a second aspect, an embodiment of the present invention provides a plunger pump provided with the automatic return deep-sea plunger pump suction and discharge structure described in the first aspect.

[0025] The beneficial effects of the present invention are as follows:

[0026] 1. The automatic return deep-sea plunger pump suction and discharge structure of this embodiment has a cross-sectional area of ​​the first plunger part that is larger than that of the second plunger part and the difference between the cross-sectional areas of the first plunger part and the second plunger part is larger than a set value, and the set value is the ratio of the set negative pressure value, the force area of ​​the inner end face of the second plunger part and the cross-sectional area of ​​the first plunger part. Therefore, during the suction and discharge process, the entire plunger is subjected to a thrust in the direction of the ball head, thereby realizing automatic return. Automatic return can be realized by designing the cross-sectional areas of the two plunger parts without the need to adopt complex structures such as a return disk, making the entire suction and discharge structure simple, reducing suction and cavitation phenomena, and avoiding the defect of severe wear of the return disk. The weight of the plunger pump can be effectively reduced, the working stability of the plunger pump can be improved, and the service life of the plunger pump can be extended.

[0027] 2. In the automatic return deep-sea plunger pump suction and discharge structure of this embodiment, the second plunger part is connected to the ball head through a connecting part, and the diameter of the connecting part is smaller than the diameter of the second plunger part, so that an annular groove is formed between the ball head and the second plunger part. When the ball head and the sliding shoe move relative to each other, the annular groove provides space for the movement of the sliding shoe, which can adapt to the situation where the sliding shoe has a large swing amplitude when the inclination angle of the swash plate is large, thereby improving the applicability of the suction and discharge structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] Figure 1 It is a schematic diagram of the overall structure of Embodiment 1 of the present invention;

[0030] Figure 2 Schematic diagram of the plunger cavity in the cylinder body of embodiment 1 of the present invention;

[0031] Figure 3 is a schematic diagram of the plunger structure of Example 1 of the present invention;

[0032] Figure 4 This is a schematic diagram of the force on the plunger of Embodiment 1 of the present invention;

[0033] Figure 5 is a schematic diagram of the plunger structure of Example 2 of the present invention;

[0034] Among them, 1. first guide end cover, 2. first guide sleeve, 3. second grid ring, 4. cylinder body, 5. first plunger, 6. first grid ring, 7. second plunger, 8. liquid inlet check valve, 9. liquid discharge check valve, 10. third grid ring, 11. second guide sleeve, 12. second guide end cover;

[0035] 401. second guide cavity, 402. second plunger cavity, 403. liquid inlet channel, 404. connecting cavity, 405. connecting channel, 406. balance channel, 407. first plunger cavity, 408. first guide cavity;

[0036] 501. external threaded shaft section, 502. right end surface of the first plunger portion, 503. first plunger portion, 504. left end surface of the first plunger portion;

[0037] 701. ball head, 702. second plunger part, 703. inner end surface of the second plunger part, 704. connecting plunger part, 705. annular mounting groove;

[0038] 801. Ball head, 802. Annular groove, 803. Connecting part, 804. Second plunger part, 805. Connecting plunger part, 806. Annular mounting groove. DETAILED DESCRIPTION

[0039] Example 1

[0040] This embodiment provides an automatic return deep-sea plunger pump suction and discharge structure, such as Figure 1 As shown, it includes a cylinder body 4, a stepped plunger cavity is provided in the cylinder body 4, a stepped plunger is provided in the stepped plunger cavity, the plunger is slidably arranged in the stepped plunger cavity, and can perform reciprocating linear motion along its own axis, one end of the plunger extends to the outside of the cylinder body and is provided with a ball head 701, and the ball head 701 is used to cooperate with the sliding shoe.

[0041] In this embodiment, the side of the plunger extending out of the cylinder body 4 is defined as the right side, and the other side of the cylinder body 4 is defined as the left side.

[0042] like Figure 2 As shown, along the direction from the left side to the right side of the cylinder body 4, the stepped piston chamber includes a first piston chamber 407, a connecting chamber 404 and a second piston chamber 402 which are coaxially arranged in sequence, and a first guide chamber 408 is coaxially arranged on the left side of the first piston chamber 407. One end of the first guide chamber 408 is connected to the first piston chamber 407, and the other end extends to the left end face of the cylinder body 4.

[0043] A second guide cavity 401 is coaxially disposed on the right side of the second plunger cavity 402 . One end of the second guide cavity 401 is communicated with the second plunger cavity 402 , and the other end extends to the right end surface of the cylinder body 4 .

[0044] Correspondingly, such as Figure 3 As shown, along the direction from the left side to the right side of the cylinder body 4, the plunger is composed of a first plunger 5 and a second plunger 7. The overall plunger structure formed by the combination includes a first plunger portion 503, a connecting plunger portion 704 and a second plunger portion 702 which are coaxially arranged in sequence. The first plunger portion 503, the connecting plunger portion 704 and the second plunger portion 702 all adopt a cylindrical structure, and the first guide cavity 408, the first plunger cavity 407, the connecting cavity 404, the second plunger cavity 402 and the second guide cavity 401 also adopt cylindrical cavities.

[0045] The first plunger portion 503 is slidably matched with the first plunger cavity 407 , the second plunger portion 702 is slidably matched with the second plunger cavity 402 , the connecting plunger portion 704 passes through the connecting cavity 404 , and the connecting plunger portion 704 is slidably matched with the connecting cavity 404 .

[0046] In order to isolate the pressure of the first plunger cavity 407 and the second plunger cavity 402, a first seal is provided between the connecting plunger portion 704 and the cavity surface of the connecting cavity 404. Preferably, the first seal adopts a first grid ring 6, and the first grid ring 6 is arranged in an annular mounting groove 705 arranged on the outer peripheral surface of the connecting plunger portion 704.

[0047] The diameter of the connecting plunger portion 704 is smaller than the diameters of the first plunger portion 503 and the second plunger portion 702, and the diameter of the second plunger portion 702 is smaller than the diameter of the first plunger portion 503. Correspondingly, the diameter of the connecting cavity 404 is smaller than the diameters of the first plunger cavity 407 and the second plunger cavity 402, and the diameter of the second plunger cavity 402 is smaller than the diameter of the first plunger cavity 407.

[0048] Furthermore, in order to guide the movement of the first plunger part 503, the diameter of the first guide cavity 408 is larger than the diameter of the first plunger cavity 407, and a first guide sleeve 2 is provided between the first plunger part 503 and the cavity surface of the first guide cavity 408, and the first plunger part 503 is slidably connected to the first guide sleeve 2 to guide its movement.

[0049] A first guide end cover 1 is provided on the left side of the first guide sleeve 2, and a second seal is provided on the right side. The first guide end cover 1 is fixedly connected to the left end face of the cylinder body 4, and the second seal is pressed against the step surface formed by the first guide cavity 408 and the first plunger cavity 407 through the first guide sleeve 1.

[0050] Preferably, the first guide end cover 1 is fixed to the left end surface of the cylinder body 4 by a plurality of bolts, and the second sealing member adopts a second grid ring 3.

[0051] Furthermore, in order to guide the movement of the second plunger part 702, the diameter of the second guide cavity 401 is larger than the diameter of the second plunger cavity 702, and a second guide sleeve 11 is provided between the second plunger part 702 and the cavity surface of the second guide cavity 401, and the second plunger part 702 is slidably connected to the second guide sleeve 11 to guide its movement.

[0052] A second guide end cover 12 is provided on the right side of the second guide sleeve 11, and a third sealing member is provided on the left side of the second guide sleeve 11. The second guide end cover 12 is fixed to the right end surface of the cylinder body 4, and the third sealing member is pressed against the step surface formed by the second guide cavity 401 and the second plunger cavity 402 through the second guide sleeve 11.

[0053] Preferably, the second guide end cover 12 is fixed to the right end surface of the cylinder body 4 by a plurality of bolts, and the third sealing member is a third grid ring 10 .

[0054] The cylinder body is provided with a liquid inlet channel 403 and a liquid discharge channel. One end of the liquid inlet channel 403 is connected to the second plunger cavity 402, and the other end extends to the surface of the cylinder body 4. One end of the liquid discharge channel is connected to the second plunger cavity 402, and the other end extends to the surface of the cylinder body 4 for connecting to an external water tank.

[0055] The liquid inlet channel 403 is provided with a liquid inlet one-way valve 8 so that the liquid in the liquid inlet channel 403 can only flow from the outside of the cylinder body 4 toward the second plunger chamber 402 .

[0056] The discharge channel is provided with a discharge one-way valve 9 so that the liquid in the discharge channel can only flow from the second plunger cavity 402 toward the outside of the cylinder body 4 .

[0057] The first plunger cavity 407 is connected to one end of a balancing channel 406 arranged in the cylinder body, and the other end of the balancing channel 406 extends to the surface of the cylinder body 4, and the end extending to the surface of the cylinder body 4 is provided with a plug 13 for sealing, and a connecting channel 405 is provided between the balancing channel 406 and the liquid inlet channel 403, one end of the connecting channel 405 is connected to the balancing channel 406, and the other end is connected to the liquid inlet channel 403, and the connection position with the liquid inlet channel 403 is located upstream of the liquid inlet check valve 8.

[0058] When the plunger reciprocates, the volume between the left end face of the second plunger part 702 and the left end 410 of the second plunger chamber 402 changes. When the plunger advances, the plunger moves to the right, the discharge one-way valve 9 opens, and the suction one-way valve 8 closes, completing the discharge process. When the plunger returns, the plunger moves to the left, the suction one-way valve 8 opens, and the discharge one-way valve 9 closes, completing the suction process.

[0059] In this embodiment, the cross-sectional area S1 of the first plunger portion 503 is greater than the cross-sectional area S4 of the second plunger portion 702, and the difference between the cross-sectional areas of the first plunger portion 503 and the second plunger portion 702 is greater than a set value; the set value is the ratio of the product of the set negative pressure value P3, the force area S3 of the inner end face 703 of the second plunger portion, and the ambient pressure P1. With this setting, during the suction and discharge process, the entire plunger is subjected to a thrust toward the ball head, thereby achieving automatic return.

[0060] The negative pressure value P3 and the ambient pressure P1 can be set according to the actual seawater environment, which will not be described in detail here.

[0061] Specifically, Figure 4 As shown, the area of ​​the left end face 504 of the first plunger part is S1. When it is in a seawater environment, the environmental pressure it is subjected to is P1, and P1 is facing the right side. The force-bearing area of ​​the right end face 502 of the first plunger part is S2, and S2 is the difference between the cross-sectional area of ​​the first plunger part 503 and the cross-sectional area of ​​the connecting plunger part 704. The force it is subjected to is P2. Since the first plunger cavity 407 is connected to the external water tank through the balance channel 406 and the connecting channel 405, the water pressure in the external water tank is very small, so P2 can be ignored, so P2=0. The force-bearing area of ​​the left end face 703 of the second plunger part is S3, and S3 is the difference between the cross-sectional area of ​​the second plunger part and the cross-sectional area of ​​the connecting plunger part. The force on the left end face 703 of the second plunger part is P3. The area of ​​the right end face of the second plunger part is S4. When it is in a seawater environment, the environmental pressure it is subjected to is P4, and P4 is facing the left side, and P1=P4.

[0062] When in the water absorption stroke, the plunger moves to the right, P3 faces the left, the volume of the second plunger cavity on the left side of the second plunger part 702 increases, forming a negative pressure, the P3 value is very small, the liquid absorption check valve 8 is opened, the liquid discharge check valve 9 is closed, P1 is the ambient pressure, P2 = 0, and the overall force of the plunger is as follows:

[0063] F1=P1S1-P3S3-P4S4=P1(S1-S4)-P3S3

[0064] because Therefore, F1>0, the entire plunger is pushed toward the ball head, that is, toward the right side, thus completing the automatic return.

[0065] When in the drainage stroke, the plunger moves to the left, the volume of the second plunger cavity on the left side of the second plunger part 702 decreases, forming a high pressure, and P3 is equal to the external environmental pressures P1 and P4, the suction check valve 8 is closed, and the discharge check valve 9 is opened, and the overall force on the plunger is as follows:

[0066] F2=P1S1+P3S3-P4S4=P1(S1-S4)+P3S3

[0067] Since S1-S4 is greater than 0, S1-S4>-S3, so F2>0, the entire plunger is pushed toward the ball head, that is, to the right, and can complete automatic return.

[0068] In this embodiment, automatic return can be achieved by designing the cross-sectional area of ​​the two plunger parts without the need to adopt complex structures such as a return plate, thereby simplifying the entire suction and discharge structure, reducing suction and cavitation phenomena, and avoiding the defect of severe wear of the return plate. The weight of the plunger pump can be effectively reduced, the working stability of the plunger pump can be improved, and the service life of the plunger pump can be extended.

[0069] Furthermore, in this embodiment, the first plunger portion and the connecting plunger portion 704 are coaxial integrated structures, and an internal threaded hole is provided on the left side of the connecting plunger portion 704. Correspondingly, the right end face of the first plunger portion 503 is provided with an external threaded shaft segment 501 matching the internal threaded hole, and the external threaded shaft segment 501 is threadedly connected to the connecting plunger portion 704 through the internal threaded hole, so that the first plunger portion 503, the second plunger portion 702 and the connecting plunger portion 704 form an integral plunger structure.

[0070] Example 2

[0071] This embodiment provides an automatic return deep-sea plunger pump suction and discharge structure, such as Figure 5As shown, compared with Example 1, the difference lies in that the first plunger portion 807, the connecting plunger portion 805 and the second plunger portion 804 adopt an integrated structure, the outer peripheral surface of the connecting plunger portion 805 is provided with an annular mounting groove 806 for installing the first seal, and a connecting portion 803 is provided between the right end portion of the second plunger portion 804 and the ball head 801, and the diameter of the connecting portion 803 is smaller than the diameter of the second plunger portion 804, so that an annular groove 802 is formed between the ball head 801 and the second plunger portion 804, and when the ball head 801 and the sliding shoe move relative to each other, the annular groove provides space for the movement of the sliding shoe, can adapt to the situation where the sliding shoe swings with a large amplitude when the inclination angle of the swash plate is large, and improves the applicability of the suction and discharge structure.

[0072] Furthermore, the connecting portion 802 is integrally connected to the second plunger portion 804 and the ball head 801 .

[0073] Example 3

[0074] This embodiment provides a plunger pump, which is provided with the automatic return deep-sea plunger pump suction and discharge structure described in Example 1 or Example 2. The remaining structure of the plunger pump can adopt the existing technology and will not be described in detail here.

[0075] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An automatic return deep-sea plunger pump suction and discharge structure, including a cylinder body, characterized in that: A stepped plunger cavity is provided in the cylinder body, the stepped plunger cavity includes a first plunger cavity, a connecting cavity and a second plunger cavity which are coaxially and sequentially arranged, a plunger is slidably provided in the stepped plunger cavity, the plunger includes a first plunger portion which cooperates with the first plunger cavity and a second plunger portion which cooperates with the second plunger cavity, a connecting plunger portion which passes through the connecting cavity is provided between the first plunger portion and the second plunger portion, a first sealing member is provided between the connecting plunger portion and the connecting cavity, a ball head is provided at the end of the second plunger portion extending out of the cylinder body, the second plunger cavity is connected to the liquid suction channel and the liquid discharge channel, the cross-sectional area of ​​the first plunger portion is greater than the cross-sectional area of ​​the second plunger portion, and the difference between the cross-sectional area of ​​the first plunger portion and the cross-sectional area of ​​the second plunger portion is greater than a set value; The set value is the ratio of the product of the set negative pressure value, the force-bearing area of ​​the inner end surface of the second plunger part and the ambient pressure; The first plunger cavity is connected to a balance channel arranged in the cylinder body. One end of the balance channel is connected to the first plunger cavity, and the other end is provided with a plug. The balance channel is connected to one end of the connecting channel, and the other end of the connecting channel is connected to the liquid suction channel.

2. The automatic return deep-sea plunger pump suction and discharge structure according to claim 1, characterized in that: A first guide cavity is provided on the side of the first plunger cavity away from the connecting cavity. The diameter of the first guide cavity is larger than the diameter of the first plunger cavity. One end of the first guide cavity is coaxially connected to the first plunger cavity, and the other end extends to the end face of the cylinder body. A first guide sleeve is provided between the cavity surface of the first guide cavity and the first plunger part, and the first guide sleeve is slidably matched with the first plunger part.

3. The automatic return deep-sea plunger pump suction and discharge structure according to claim 2, characterized in that: One end of the first guide sleeve contacts the first guide end cover fixed on the outer end surface of the cylinder body, and the other side is provided with a second sealing member. The first guide sleeve presses the second sealing member on the step surface formed between the first plunger cavity and the first guide cavity.

4. The automatic return deep-sea plunger pump suction and discharge structure according to claim 1, characterized in that: A second guide cavity is provided on the side of the second plunger cavity away from the connecting cavity. The diameter of the second guide cavity is larger than the diameter of the second plunger cavity. One end of the second guide cavity is connected to the second plunger cavity, and the other end extends to the end surface of the cylinder body. A second guide sleeve is provided between the cavity surface of the second guide cavity and the second plunger part, and the second guide sleeve is slidably matched with the second plunger part.

5. The automatic return deep-sea plunger pump suction and discharge structure according to claim 4, characterized in that: One end of the second guide sleeve contacts the second guide end cover fixed on the outer end surface of the cylinder body, and the other side is provided with a third sealing member. The second guide sleeve presses the third sealing member onto a step surface formed between the second plunger cavity and the second guide cavity.

6. The automatic return deep-sea plunger pump suction and discharge structure according to claim 1, characterized in that: The suction channel is provided with a suction one-way valve so that the liquid in the suction channel can only flow from the outside of the cylinder body into the second plunger cavity, and the discharge channel is provided with a discharge one-way valve so that the liquid in the discharge channel can only flow from the second plunger cavity to the outside of the cylinder body.

7. The automatic return deep-sea plunger pump suction and discharge structure according to claim 1, characterized in that: The second plunger part is integrally connected to the connecting plunger part, one end of the connecting plunger part is connected to the second plunger part, and the other end is provided with an internal threaded hole, and the end of the first plunger part used for connecting the connecting plunger part is provided with an external threaded shaft section, and the external threaded shaft section is threadedly connected to the internal threaded hole to connect the first plunger part, the connecting plunger part and the second plunger part into a whole; or The first plunger portion, the second plunger portion and the connecting plunger portion are integrally connected.

8. The automatic return deep-sea plunger pump suction and discharge structure according to claim 1, characterized in that: A connecting portion is provided between the end of the second plunger portion extending outside the cylinder body and the ball head, and a diameter of the connecting portion is smaller than a diameter of the second plunger portion.

9. A plunger pump provided with the automatic return deep-sea plunger pump suction and discharge structure according to any one of claims 1 to 8.

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