screw pump

Abstract

This application relates to the field of oilfield development technology, and more particularly to a screw pump. The screw pump includes an outer stator, a rotor, an inner stator, and a drive unit. The outer stator is fitted over the rotor, forming a first helical cavity between the outer stator and the rotor. The first helical cavity has a first suction end and a first discharge end at its two ends. The rotor is fitted over the inner stator, forming a second helical cavity between the rotor and the inner stator. The second helical cavity has a second suction end and a second discharge end at its two ends, with the second suction end communicating with the first discharge end. External fluid is input into the first helical cavity from the first suction end, and the fluid sequentially passes through the first discharge end, the second suction end, the second helical cavity, and the second discharge end before being output. The first and second helical cavities convey fluid in opposite directions, which can reduce or even completely eliminate the axial thrust on the rotor, thus improving the efficiency of the screw pump and extending its service life.

Description

Technical Field

[0001] This application relates to the field of oilfield extraction technology, and in particular to a screw pump. Background Technology

[0002] When a screw pump is operating, the power unit drives the screw pump rotor to rotate, drawing underground fluid into the lower part of the pump and causing it to flow upwards and exit from the upper part. This generates an axial thrust on the screw pump rotor. To balance this axial thrust, thrust bearings are typically used. However, thrust bearings have difficulty dissipating heat underground, making them prone to damage and shortening the pump's lifespan. Furthermore, the axial thrust increases friction in the thrust bearings, reducing the pump's efficiency. Summary of the Invention

[0003] The embodiments of this application aim to provide a screw pump that can at least improve the problem of axial thrust on the screw pump rotor.

[0004] In order to solve the above-mentioned technical problems, the embodiments of this application adopt the following technical solutions:

[0005] This application provides a screw pump for conveying fluid. The screw pump includes an outer stator, a rotor, an inner stator, and a drive component. The outer stator has a first helical inner wall. The rotor has a first helical outer wall and a second helical inner wall. The outer stator is sleeved on the outside of the rotor, and a first helical cavity is formed between the first helical outer wall and the first helical inner wall. The two ends of the first helical cavity are respectively provided with a first suction end and a first discharge end. The inner stator has a second helical outer wall, and the rotor is sleeved on the outside of the inner stator. A second helical cavity is formed between the second helical outer wall and the second helical inner wall. The two ends of the second helical cavity are respectively provided with a second suction end and a second discharge end. The second suction end communicates with the first discharge end. The drive component is connected to the rotor and can drive the rotor to rotate relative to the outer stator and the inner stator, so as to input external fluid from the first suction end into the first helical cavity, and the fluid sequentially passes through the first discharge end, the second suction end, the second helical cavity, and the second discharge end before being discharged.

[0006] In some embodiments, the outer stator is further provided with a first liquid passage chamber and a first suction port, the first suction port communicating the first liquid passage chamber with the outside, and the first liquid passage chamber communicating with the first suction end.

[0007] In some embodiments, the screw pump further includes an inner cylinder rotatably disposed within the outer stator, with one end of the inner cylinder connected to one end of the rotor, a first liquid passage chamber formed between the inner cylinder and the outer stator, and the inner cylinder having a second liquid passage chamber communicating with the second discharge end.

[0008] In some embodiments, the screw pump further includes an inner shaft fixed inside the inner cylinder, with one end of the inner shaft connected to one end of the inner stator, and the inner shaft and the inner cylinder forming a second liquid passage chamber.

[0009] In some embodiments, the screw pump further includes a first fixing sleeve fixed inside the outer stator, and the first fixing sleeve is disposed on the side of the first liquid passage chamber opposite to the first suction end. The other end of the inner cylinder is rotatably connected to the first fixing sleeve, and the other end of the inner shaft is fixedly connected to the first fixing sleeve.

[0010] In some embodiments, the outer stator further includes a liquid outlet chamber located on the side of the first fixed sleeve opposite to the first liquid passage chamber. The screw pump also includes a connecting sleeve connected between the first fixed sleeve and the inner shaft. The connecting sleeve has a liquid passage hole that communicates with the liquid outlet chamber and the second liquid passage chamber.

[0011] In some embodiments, the screw pump further includes a first bearing connected between the first fixed sleeve and the inner cylinder.

[0012] In some embodiments, the screw pump further includes a first sealing ring connected between the first fixed sleeve and the inner cylinder.

[0013] In some embodiments, one end of the outer stator is further provided with a sealing cavity, which is connected to the first discharge end and the second suction end respectively.

[0014] In some embodiments, the screw pump further includes a connecting shaft, which is at least partially disposed within the sealed cavity. The drive element is connected to one end of the outer stator, and the two ends of the connecting shaft are respectively connected to the drive element and the rotor.

[0015] In some embodiments, the end of the connecting shaft opposite to the driving member is provided with a second suction port, which is connected to the sealing cavity and the second suction end respectively.

[0016] In some embodiments, the screw pump further includes a second fixed sleeve fixed inside the outer stator, and the second fixed sleeve is disposed on the side of the sealing cavity opposite to the first discharge end. The connecting shaft is rotatably connected to the second fixed sleeve. The driving member is disposed on the side of the second fixed sleeve opposite to the sealing cavity, and one end of the connecting shaft passes through the second fixed sleeve and is connected to the driving member.

[0017] In some embodiments, the screw pump further includes a second bearing connected between the second fixed sleeve and the connecting shaft.

[0018] In some embodiments, the screw pump further includes a second sealing ring, which is connected between the second fixed sleeve and the connecting shaft.

[0019] In some embodiments, the screw pump further includes a coupling connected between the drive member and the connecting shaft.

[0020] In the screw pump of this application embodiment, a second helical cavity and a first helical cavity are formed on the inner and outer sides of the rotor, respectively, and the first helical cavity and the second helical cavity convey fluid in opposite directions, thereby greatly reducing or even completely eliminating the axial thrust of the rotor, which is beneficial to improving the efficiency of the screw pump and extending its service life.

[0021] The above description is merely an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0022] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0023] Figure 1 This is a cross-sectional view of a screw pump according to an embodiment of this application;

[0024] Figure 2 yes Figure 1 A magnified view of a section at point A in the middle;

[0025] Figure 3 yes Figure 1 A magnified view of a section at point B in the middle;

[0026] Figure 4 yes Figure 1 A magnified view of a section at point C.

[0027] The reference numerals in the detailed embodiments are as follows:

[0028] 100. Screw pump;

[0029] 1. Outer stator; 1a. First hollow section; 1b. Spiral section; 1c. Second hollow section; 101. Inner wall of the first spiral; 102. First liquid passage chamber; 103. First suction inlet; 104. Liquid outlet chamber; 105. Sealing chamber;

[0030] 2. Rotor; 201. Outer wall of the first spiral; 202. Inner wall of the second spiral; 203. Connecting part; 2031. Third suction port;

[0031] 3. Inner stator; 301. Outer wall of the second helix;

[0032] 4. Drive components;

[0033] 5. Inner cylinder; 501. Second liquid passage chamber;

[0034] 6. Inner shaft; 7. First fixed sleeve; 8. First bearing; 9. First sealing ring; 10. Connecting sleeve; 1001. Liquid passage hole; 11. Second fixed sleeve; 12. Connecting shaft; 1201. Second suction port; 1202. Connecting groove; 13. Second bearing; 14. Second sealing ring; 15. Coupling;

[0035] a) First spiral cavity; a1) First suction end; a2) First discharge end;

[0036] b, second spiral cavity; b1, second suction end; b2, second discharge end. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. It should be noted that when an element is described as being "fixed" to another element, it can be directly on the other element, or one or more intervening elements may exist between them. When an element is described as being "connected" to another element, it can be directly connected to the other element, or one or more intervening elements may exist between them. It should be noted that, unless otherwise specified, the various features in the embodiments of this application can be combined with each other, all within the scope of protection of this application. Furthermore, although functional modules are divided in the device schematic diagram and a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different module division or in a different order than that shown in the device schematic diagram or the flowchart.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0039] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" 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 the embodiments of this application and simplifying the description, and are not intended to 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, they should not be construed as limitations on the embodiments of this application.

[0040] In the description of the embodiments of this application, the terms "first," "second," etc., are used to define components merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0041] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0042] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0043] Please see Figure 1 This application provides a screw pump 100 for conveying fluid. The screw pump 100 includes an outer stator 1, a rotor 2, an inner stator 3, and a drive component 4. The outer stator 1 has a first helical inner wall 101. The rotor 2 has a first helical outer wall 201 and a second helical inner wall 202. The outer stator 1 is sleeved on the outside of the rotor 2. A first helical cavity a is formed between the first helical outer wall 201 and the first helical inner wall 101. The two ends of the first helical cavity a are respectively provided with a first suction end a1 and a first discharge end a2. The inner stator 3 has a second helical outer wall 301. The rotor 2 is sleeved on the outside of the inner stator 3. A second helical cavity b is formed between the second helical outer wall 301 and the second helical inner wall 202. The two ends of the second helical cavity b are respectively provided with a second suction end b1 and a second discharge end b2. The second suction end b1 communicates with the first discharge end a2. The drive unit 4 is connected to the rotor 2. The drive unit 4 can drive the rotor 2 to rotate relative to the outer stator 1 and the inner stator 3 so as to input the external fluid from the first suction end a1 into the first spiral cavity a, and the fluid is output sequentially through the first discharge end a2, the second suction end b1, the second spiral cavity b and the second discharge end b2.

[0044] For the aforementioned outer stator 1, please refer to Figure 1 The outer stator 1 is hollow and includes a first hollow section 1a, a helical section 1b, and a second hollow section 1c connected in sequence. The inner diameters of the first hollow section 1a and the second hollow section 1c are both larger than the inner diameter of the helical section 1b. The helical section 1b has a first intake end a1 facing the first hollow section 1a and a first discharge end a2 facing the second hollow section 1c. The inner wall of the helical section 1b is helical to form a first helical inner wall 101, and the rotor 2 is at least partially disposed within the helical section 1b.

[0045] In some embodiments, the outer stator 1 is configured with a double-layer structure, comprising an outer stator layer and an inner stator layer (not shown in the figure). The outer stator layer covers the inner stator layer, and the first spiral inner wall 101 is disposed in the inner stator layer. The outer stator layer is made of a metallic material, such as stainless steel or galvanized alloy, to ensure the strength of the outer stator 1. The inner stator layer is made of a flexible material, such as rubber or silicone, to improve deformability and adaptability, thereby ensuring the sealing performance of the first spiral cavity a. It is understood that in some other embodiments, the outer stator 1 may also be configured with a single-layer structure, such as being made only of metallic materials or only of non-metallic materials; this is not limited here.

[0046] For rotor 2 mentioned above, please refer to Figure 1 The rotor 2 is hollow, and its outer wall is spiral-shaped to form a first spiral outer wall 201. The inner wall of the rotor 2 is spiral-shaped to form a second spiral inner wall 202. The spiral directions of the first spiral outer wall 201 and the second spiral inner wall 202 are opposite. The first spiral outer wall 201 meshes with the first spiral inner wall 101.

[0047] In some embodiments, the rotor 2 is configured with a double-layer structure, including an outer rotor layer and an inner rotor layer (not shown in the figure). The outer rotor layer covers the inner rotor layer, a first helical outer wall 201 is disposed on the outer rotor layer, and a second helical inner wall 202 is disposed on the inner rotor layer. The outer rotor layer is made of a metal material, such as stainless steel or galvanized alloy, to ensure the strength of the rotor 2; the inner rotor layer is made of rubber to improve deformability and adaptability, thereby ensuring the sealing performance of the second helical cavity b.

[0048] It is understood that in some other embodiments, the rotor 2 may also have an outer layer made of rubber and an inner layer made of metal. In some other embodiments, the rotor 2 may also have a single-layer structure, such as being made only of metal or only of non-metallic materials, and this is not limited here.

[0049] For the aforementioned inner stator 3, please refer to Figure 1 The inner stator 3 is generally cylindrical, and its outer wall is spiral-shaped to form a second spiral outer wall 301, which meshes with the second spiral inner wall 202. The second spiral outer wall 301 has a second discharge end b2 at one end facing the first hollow section 1a, and a second suction end b1 at the other end facing the second hollow section 1c. The inner stator 3 is configured not to rotate relative to the outer stator 1, allowing the rotor 2 to rotate simultaneously relative to both the outer stator 1 and the inner stator 3. The inner stator 3 is made of metal, such as stainless steel or galvanized alloy, to enhance its strength.

[0050] The aforementioned drive component 4 is detachably mounted on the outer stator 1, and its output shaft is connected to the rotor 2, allowing the rotor 2 to rotate. The drive component 4 is an electric motor. It is understood that in some other embodiments, the structure of the drive component 4 can be customized according to actual needs, such as using a rotary cylinder or a rotary hydraulic cylinder, which is not limited here.

[0051] Understandably, the first spiral inner wall 101 and the first spiral outer wall 201 are designed to form a first spiral cavity a between the outer stator 1 and the rotor 2. When the rotor 2 rotates in the outer stator 1, the first spiral outer wall 201 applies a thrust toward the first discharge end a2 to the fluid in the first spiral cavity a, so as to transport the fluid in the first spiral cavity a to the first discharge end a2. Similarly, when the rotor 2 rotates around the inner stator 3, the second spiral inner wall 202 applies a thrust toward the second discharge end b2 to the fluid in the second spiral cavity b, so as to transport the fluid in the second spiral cavity b to the second discharge end b2.

[0052] It should be noted that in this embodiment, the second suction end b1 and the first discharge end a2 are located at the same end of the rotor 2, and the second suction end b1 is connected to the first discharge end a2. Therefore, the fluid flow directions in the first helical cavity a and the second helical cavity b are opposite, that is, the thrust directions of the first helical outer wall 201 and the second helical inner wall 202 on the fluid are opposite, thereby significantly reducing or even completely eliminating the axial thrust of the rotor 2. In the prior art, the axial thrust of the rotor 2 is usually counteracted by a thrust bearing. The thrust bearing needs to be equipped with a seal to isolate the lubricating oil and the pumped fluid, resulting in difficulty in heat dissipation of the thrust bearing. Therefore, a large axial thrust will aggravate the heating and damage of the thrust bearing, accelerate the damage of the thrust bearing, and shorten the service life of the screw pump 100. Furthermore, the axial thrust leads to an increase in the friction of the thrust bearing, reducing the speed of the rotor 2 and reducing the efficiency of the screw pump 100. The embodiments of this application can significantly reduce or even completely eliminate the axial thrust of the rotor 2, thereby reducing the wear of the thrust bearing, extending the service life of the screw pump 100, and reducing the cost and failure rate of the screw pump 100. Furthermore, it reduces the friction of the thrust bearing, improving the efficiency of the screw pump 100. Optionally, the screw pump 100 can omit the thrust bearing, i.e., use a radial bearing, which helps to reduce the cost of the screw pump 100.

[0053] In some embodiments, please refer to Figure 1 The outer stator 1 is also provided with a first liquid passage chamber 102 and a first suction port 103. The first liquid passage chamber 102 is located inside the first hollow section 1a, and the first suction port 103 is disposed on the wall of the first hollow section 1a. The first suction port 103 connects the first liquid passage chamber 102 to the outside and is also connected to the first suction end a1. When the screw pump 100 is working, the outer stator 1 is placed in the external fluid, and the external fluid covers the first suction port 103, allowing the external fluid to be drawn into the first suction end a1. There can be multiple first suction ports 103, which are spaced apart.

[0054] In some embodiments, please refer to Figure 1The screw pump 100 also includes an inner cylinder 5, which is rotatably disposed within the first hollow section 1a of the outer stator 1, forming a first liquid passage chamber 102 between the inner cylinder 5 and the first hollow section 1a. Specifically, one end of the rotor 2 away from the drive member 4 extends into the first hollow section 1a, one end of the inner cylinder 5 is connected to the end of the rotor 2 away from the drive member 4, and the other end of the inner cylinder 5 is rotatably connected to the outer stator 1. The rotor 2 can drive the inner cylinder 5 to rotate relative to the outer stator 1. The inner cylinder 5 is hollow, and a second liquid passage chamber 501 is provided inside the inner cylinder 5, which communicates with the second discharge end b2. The inner cylinder 5 is made of a flexible material, such as flexible metal, plastic, or composite material, which can both deform and withstand torque. When the screw pump 100 is working, the rotor 2 rotates eccentrically relative to the outer stator 1. Therefore, the inner cylinder 5 is made of a flexible material so that it can deform during rotation, avoiding rigid impact, reducing noise, and extending service life.

[0055] In some embodiments, please refer to Figure 1 The screw pump 100 also includes an inner shaft 6, which is fixed inside the inner cylinder 5, forming a second liquid passage chamber 501 between the inner shaft 6 and the inner cylinder 5. Specifically, one end of the inner stator 3 away from the drive member 4 extends into the first hollow section 1a, and one end of the inner shaft 6 is connected to the end of the inner stator 3 away from the drive member 4; the other end of the inner shaft 6 extends to the outside of the inner cylinder 5, and is fixedly connected to the outer stator 1, so that the outer stator 1 and the inner stator 3 are fixed together. The inner shaft 6 is made of a flexible material, such as flexible metal, plastic, or composite material, which can both deform and withstand torque. When the rotor 2 rotates relative to the inner stator 3, it will cause the inner stator 3 to move circumferentially. Therefore, the inner shaft 6 is made of a flexible material so that the inner stator 3 can deform during circumferential displacement, avoiding rigid impact, reducing noise, and extending service life.

[0056] In some embodiments, please refer to Figure 2 The screw pump 100 also includes a first fixed sleeve 7, which is fixed inside the outer stator 1. The first fixed sleeve 7 is disposed on the side of the first liquid passage chamber 102 away from the first suction end a1. The end of the inner shaft 6 away from the inner stator 3 is fixedly connected to the first fixed sleeve 7, and the end of the inner cylinder 5 away from the rotor 2 is rotatably connected to the first fixed sleeve 7. Specifically, the first fixed sleeve 7 is detachably disposed inside the first hollow section 1a, and the first fixed sleeve 7 is respectively sleeved on the outer side of the inner cylinder 5 and the inner shaft 6. The first hollow section 1a, the inner cylinder 5, and the first fixed sleeve 7 together enclose the first liquid passage chamber 102.

[0057] In some embodiments, please refer to Figure 2The screw pump 100 also includes a first bearing 8, which is connected between the first fixed sleeve 7 and the inner cylinder 5. The first bearing 8 rotatably connects the inner cylinder 5 and the first fixed sleeve 7, which helps reduce the friction between them. In this embodiment, the first bearing 8 is a sliding copper sleeve. It is understood that in some other embodiments, the first bearing can be configured according to actual needs, such as a ball bearing, a sliding bearing, or a thrust bearing, and is not limited here.

[0058] In some embodiments, please refer to Figure 2 The screw pump 100 also includes a first sealing ring 9, which is connected between the first fixed sleeve 7 and the inner cylinder 5. Specifically, the first sealing ring 9 is sleeved on the outer wall of the inner cylinder 5, abuts against the inner wall of the first fixed sleeve 7, and is located at the end of the first bearing 8 away from the first liquid passage chamber 102, so as to increase the sealing effect between the first fixed sleeve 7 and the inner cylinder 5.

[0059] In some embodiments, please refer to Figure 1 and Figure 2 The outer stator 1 is also provided with a liquid outlet chamber 104, which is located on the side of the first fixed sleeve 7 opposite to the first liquid passage chamber 102. Specifically, the liquid outlet chamber 104 is located in the middle of the first hollow section 1a, dividing the interior of the first hollow section 1a into the first liquid passage chamber 102 and the liquid outlet chamber 104. The liquid outlet chamber 104 communicates with the second liquid passage chamber 501, and the fluid from the second discharge end b2 can be discharged to the liquid outlet chamber 104 through the second liquid passage chamber 501.

[0060] In some embodiments, please refer to Figure 2 The screw pump 100 also includes a connecting sleeve 10, which connects the first fixed sleeve 7 and the inner shaft 6. Specifically, the first fixed sleeve 7 has a mounting groove at one end away from the first liquid passage chamber 102. The connecting sleeve 10 is disposed in the mounting groove and sleeved over the inner shaft 6, so that the inner shaft 6 is fixedly connected to the first fixed sleeve 7. The connecting sleeve 10 has liquid passage holes 1001, which are respectively connected to the liquid outlet chamber 104 and the second liquid passage chamber 501. Fluid in the second liquid passage chamber 501 can be discharged to the liquid outlet chamber 104 through the liquid passage holes 1001. There can be multiple liquid passage holes 1001, which are distributed at intervals around the central axis of the connecting sleeve 10.

[0061] In some embodiments, the connecting sleeve 10 is detachably disposed on the first fixed sleeve 7. During installation, the inner shaft 6 is first connected to the connecting sleeve 10, thereby facilitating the assembly and maintenance of the screw pump 100. The connecting sleeve 10 is annular, and the inner shaft 6 can be directly inserted into the connecting sleeve 10, thus eliminating the need for fasteners such as screws. This improves the efficiency of disassembly and assembly between the inner shaft 6 and the connecting sleeve 10 and reduces the cost of the screw pump 100. The hole in the middle of the connecting sleeve 10 can be non-circular, such as square or hexagonal, and is adapted to the end of the inner shaft 6 inserted into the connecting sleeve 10, thereby preventing the inner shaft 6 from rotating relative to the connecting sleeve 10. Similarly, the hole in the middle of the first fixed sleeve 7 can be non-circular, such as square or hexagonal, and is adapted to the contour of the connecting sleeve 10, thereby preventing the connecting sleeve 10 from rotating relative to the first fixed sleeve 7.

[0062] In some embodiments, please refer to Figure 1 The outer stator 1 is also provided with a sealing cavity 105 at one end, which is connected to the first discharge end a2 and the second suction end b1 respectively. Specifically, the second hollow section 1c is provided with a sealing cavity 105 inside, and the fluid from the first discharge end a2 is drawn into the second spiral cavity b from the second suction end b1 after passing through the sealing cavity 105.

[0063] In some embodiments, please refer to Figure 3 The screw pump 100 also includes a second fixing sleeve 11, which is fixed inside the outer stator 1. The second fixing sleeve 11 is disposed on the side of the sealing cavity 105 away from the first discharge end a2, and seals the end of the sealing cavity 105 through the second fixing sleeve 11. The second fixing sleeve 11 is detachably connected to the outer stator 1, which facilitates the maintenance and disassembly of the screw pump 100.

[0064] In some other embodiments, please refer to Figure 1 The screw pump 100 also includes a connecting shaft 12, which is at least partially disposed within the sealing cavity 105. The connecting shaft 12 is rotatably inserted through the second fixed sleeve 11, and its two ends are respectively connected to the drive member 4 and the rotor 2. Specifically, the drive member 4 is connected to the end of the second hollow section 1c opposite to the helical section 1b, and one end of the rotor 2 extends from the helical section 1b into the sealing cavity 105. The output shaft of the drive member 4 is connected to one end of the connecting shaft 12, and the other end of the connecting shaft 12 extends through the second fixed sleeve 11 into the sealing cavity 105 and connects to the rotor 2. By providing the connecting shaft 12, the drive member 4 outside the sealing cavity 105 can be connected to the rotor 2, preventing the drive member 4 from contacting the fluid inside the sealing cavity 105. The inner shaft 6 is made of a flexible material, such as flexible metal, plastic, or composite material, which can both deform and withstand torque.

[0065] In some embodiments, please refer to Figure 4The connecting shaft 12 has a second suction port 1201 at one end opposite to the drive component 4. The second suction port 1201 is connected to the sealing cavity 105 and the second suction end b1. The second suction port 1201 is located near the port of the rotor 2, thereby communicating with the second suction end b1 inside the rotor 2. There can be multiple second suction ports 1201, which are spaced apart circumferentially along the connecting shaft 12.

[0066] In some embodiments, please refer to Figure 4 One end of the rotor 2 is provided with a connecting portion 203, and one end of the connecting shaft 12 is provided with a connecting groove 1202. The connecting portion 203 is inserted into the connecting groove 1202 to connect the rotor 2 and the connecting shaft 12. The connecting portion 203 is provided with a third suction port 2031, which communicates with the interior of the rotor 2 and is directly opposite the second suction port 1201. The number of second suction ports 1201 and third suction ports 2031 are equal and correspond one-to-one to increase the flow rate of the sealed cavity 105 into the second suction end b1. The second suction port 1201 is located on the groove wall of the connecting groove 1202, thereby communicating with the third suction port 2031 of the connecting portion 203 and with the sealed cavity 105 outside the connecting shaft 12.

[0067] In some embodiments, please refer to Figure 3 The screw pump 100 also includes a second bearing 13, which is connected between the second fixed sleeve 11 and the connecting shaft 12. The second bearing 13 rotatably connects the connecting shaft 12 and the second fixed sleeve 11, which helps reduce the friction between them. In this embodiment, the second bearing 13 is a sliding copper sleeve. It is understood that in some other embodiments, the structure of the second bearing 13 can be configured according to actual needs, such as a ball bearing, a sliding bearing, or a thrust bearing, etc., and is not limited here.

[0068] In some embodiments, please refer to Figure 3 The screw pump 100 also includes a second sealing ring 14, which is connected between the second fixed sleeve 11 and the connecting shaft 12 to increase the sealing effect between the second fixed sleeve 11 and the connecting shaft 12.

[0069] In some embodiments, please refer to Figure 3 The screw pump 100 also includes a coupling 15, which connects the drive component 4 and the connecting shaft 12. The coupling 15 facilitates the installation and removal of the drive component 4.

[0070] In the screw pump 100 of this application embodiment, a second helical cavity b and a first helical cavity a are formed on the inner and outer sides of the rotor 2, respectively. The first helical cavity a and the second helical cavity b convey fluid in opposite directions, thereby greatly reducing or even completely eliminating the axial thrust of the rotor 2, which is beneficial to improving the efficiency of the screw pump 100 and extending its service life.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them; under the concept of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of this application as described above, which are not provided in detail for the sake of brevity; although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A screw pump for conveying fluid, characterized in that, include: The outer stator has a first spiral inner wall; The rotor has a first helical outer wall and a second helical inner wall, the helical directions of the first helical outer wall and the second helical inner wall are opposite, the outer stator is sleeved on the outside of the rotor, a first helical cavity is formed between the first helical outer wall and the first helical inner wall, and a first suction end and a first discharge end are respectively provided at both ends of the first helical cavity; The inner stator has a second spiral outer wall, and the rotor is sleeved on the outside of the inner stator. A second spiral cavity is formed between the second spiral outer wall and the second spiral inner wall. The two ends of the second spiral cavity are respectively provided with a second suction end and a second discharge end. The second suction end and the first discharge end are located at the same end of the rotor, and the second suction end is connected to the first discharge end. A driving component is connected to the rotor. The driving component can drive the rotor to rotate relative to the outer stator and the inner stator so as to input external fluid from the first suction end into the first spiral cavity, and the fluid sequentially passes through the first discharge end, the second suction end, the second spiral cavity and the second discharge end for output. The fluid flow directions in the first spiral cavity and the second spiral cavity are opposite.

2. The screw pump according to claim 1, characterized in that, The outer stator is further provided with a first liquid passage chamber and a first suction port. The first suction port connects the first liquid passage chamber to the outside, and the first liquid passage chamber is connected to the first suction end.

3. The screw pump according to claim 2, characterized in that, The screw pump also includes an inner cylinder, which is rotatably disposed inside the outer stator, and one end of the inner cylinder is connected to one end of the rotor. A first liquid passage chamber is formed between the inner cylinder and the outer stator. The inner cylinder is provided with a second liquid passage chamber, which is connected to the second discharge end.

4. The screw pump according to claim 3, characterized in that, The screw pump also includes an inner shaft, which is fixed inside the inner cylinder, and one end of the inner shaft is connected to one end of the inner stator. The inner shaft and the inner cylinder form the second liquid passage chamber.

5. The screw pump according to claim 4, characterized in that, The screw pump also includes a first fixing sleeve, which is fixed inside the outer stator, and the first fixing sleeve is disposed on the side of the first liquid passage chamber opposite to the first suction end; The other end of the inner cylinder is rotatably connected to the first fixed sleeve, and the other end of the inner shaft is fixedly connected to the first fixed sleeve.

6. The screw pump according to claim 5, characterized in that, The outer stator is also provided with a liquid outlet cavity, which is located on the side of the first fixed sleeve opposite to the first liquid outlet cavity; The screw pump also includes a connecting sleeve, which is connected between the first fixed sleeve and the inner shaft. The connecting sleeve is provided with a liquid passage hole, which is connected to the liquid outlet chamber and the second liquid passage chamber respectively.

7. The screw pump according to claim 5, characterized in that, The screw pump further includes a first bearing, which is connected between the first fixed sleeve and the inner cylinder; and / or The screw pump also includes a first sealing ring, which is connected between the first fixed sleeve and the inner cylinder.

8. The screw pump according to any one of claims 1-7, characterized in that, One end of the outer stator is also provided with a sealing cavity, which is connected to the first discharge end and the second suction end respectively.

9. The screw pump according to claim 8, characterized in that, The screw pump also includes a connecting shaft, which is at least partially disposed within the sealed cavity; The drive unit is connected to one end of the outer stator, and the two ends of the connecting shaft are respectively connected to the drive unit and the rotor.

10. The screw pump according to claim 9, characterized in that, The end of the connecting shaft opposite to the driving component is provided with a second suction port, which is connected to the sealing cavity and the second suction end respectively.

11. The screw pump according to claim 9, characterized in that, The screw pump also includes a second fixed sleeve, which is fixed inside the outer stator, and the second fixed sleeve is disposed on the side of the sealing cavity opposite to the first discharge end, and the connecting shaft is rotatably connected to the second fixed sleeve; The driving component is disposed on the side of the second fixed sleeve away from the sealing cavity, and one end of the connecting shaft passes through the second fixed sleeve and is connected to the driving component.

12. The screw pump according to claim 11, characterized in that, The screw pump further includes a second bearing, which is connected between the second fixed sleeve and the connecting shaft; and / or The screw pump further includes a second sealing ring, which is connected between the second fixed sleeve and the connecting shaft; and / or The screw pump also includes a coupling that connects the drive unit and the connecting shaft.

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