Screw pump

Abstract

The invention relates to the technical field of oilfield exploitation, in particular to a screw pump. The screw pump includes an outer stator, a rotor, an inner stator, and a driving member. The rotor is sleeved with the outer stator, a first spiral cavity is formed between the outer stator and the rotor, and a first suction end and a first discharge end are arranged at the two ends of the first spiral cavity respectively. The rotor is sleeved outside the inner stator, a second spiral cavity is formed between the rotor and the inner stator, two ends of the second spiral cavity are respectively provided with a second suction end and a second discharge end, and the second suction end is communicated with the first discharge end. External fluid is input into the first spiral cavity from the first suction end, and the fluid sequentially passes through the first discharge end, the second suction end, the second spiral cavity and the second discharge end to be output. The first spiral cavity and the second spiral cavity are opposite in fluid conveying direction, axial thrust borne by the rotor can be reduced or even completely eliminated, the efficiency of the screw pump can be improved, and the service life of the screw pump is prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of oilfield exploitation, and in particular to a screw pump. Background Art

[0002] When the screw pump is working, the power equipment drives the screw pump rotor to rotate, sucking the underground fluid through the lower part of the screw pump, and causing the fluid to flow upward and be discharged from the upper end of the screw pump, thus generating axial thrust on the screw pump rotor. In order to balance the axial thrust of the screw pump rotor, thrust bearings are usually used. Thrust bearings are difficult to dissipate heat underground and are easily damaged, shortening the service life of the screw pump. In addition, the axial thrust increases the friction of the thrust bearing, reducing the efficiency of the screw pump. Summary of the invention

[0003] The embodiment of the present application aims to provide a screw pump, so as to at least improve the problem of the screw pump rotor being subjected to axial thrust.

[0004] In order to solve the above technical problems, the embodiments of the present application adopt the following technical solutions: The embodiment of the present application provides a screw pump for conveying fluid, and the screw pump includes an outer stator, a rotor, an inner stator and a driving member. The outer stator is provided with a first spiral inner wall. The rotor is provided with a first spiral outer wall and a second spiral inner wall, the outer stator is sleeved outside the rotor, a first spiral cavity is formed between the first spiral outer wall and the first spiral inner wall, and a first suction end and a first discharge end are respectively provided at both ends of the first spiral cavity. The inner stator is provided with a second spiral outer wall, the rotor is sleeved outside the inner stator, a second spiral cavity is formed between the second spiral outer wall and the second spiral inner wall, and a second suction end and a second discharge end are respectively provided at both ends of the second spiral cavity, and the second suction end is communicated with the first discharge end. The driving member is connected to the rotor, and the driving member can drive the rotor to rotate relative to the outer stator and the inner stator, so as to input the external fluid from the first suction end into the first spiral cavity, and the fluid is sequentially output through the first discharge end, the second suction end, the second spiral cavity and the second discharge end.

[0005] In some embodiments, the outer stator is further provided with a first liquid passage cavity and a first suction port, the first suction port connects the first liquid passage cavity with the outside, and the first liquid passage cavity is connected with the first suction end.

[0006] In some embodiments, the screw pump also includes an inner cylinder, which is rotatably disposed in the outer stator, and one end of the inner cylinder is connected to one end of the rotor, and the first liquid passage chamber is formed between the inner cylinder and the outer stator, and the inner cylinder is provided with a second liquid passage chamber, and the second liquid passage chamber is connected to the second discharge end.

[0007] In some embodiments, the screw pump further includes an inner shaft fixed in the inner cylinder, and one end of the inner shaft is connected to one end of the inner stator, and the second liquid passage chamber is formed between the inner shaft and the inner cylinder.

[0008] In some embodiments, the screw pump further comprises a first fixed sleeve, which is fixed in the outer stator, and the first fixed sleeve is arranged on the side of the first liquid passage chamber away from 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.

[0009] In some embodiments, the outer stator is further provided with a liquid outlet cavity, and the liquid outlet cavity is provided on a side of the first fixed sleeve away from the first liquid passage cavity. The screw pump further comprises a connecting sleeve, and the connecting sleeve is connected between the first fixed sleeve and the inner shaft, and the connecting sleeve is provided with a liquid passage hole, and the liquid passage hole is respectively connected to the liquid outlet cavity and the second liquid passage cavity.

[0010] In some embodiments, the screw pump further includes a first bearing connected between the first fixing sleeve and the inner cylinder.

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

[0012] In some embodiments, a sealed cavity is further provided at one end of the outer stator, and the sealed cavity is respectively connected to the first discharge end and the second suction end.

[0013] In some embodiments, the screw pump further comprises a connecting shaft, wherein at least a portion of the connecting shaft is disposed in the sealed cavity. The driving member is connected to one end of the outer stator, and two ends of the connecting shaft are respectively connected to the driving member and the rotor.

[0014] In some embodiments, a second suction port is provided at an end of the connecting shaft away from the driving member, and the second suction port is respectively connected to the sealing cavity and the second suction end.

[0015] In some embodiments, the screw pump further comprises a second fixed sleeve fixed in the outer stator, and the second fixed sleeve is arranged on a side of the sealed cavity away from the first discharge end, and the connecting shaft is rotatably connected to the second fixed sleeve. The driving member is arranged on a side of the second fixed sleeve away from the sealed cavity, and one end of the connecting shaft passes through the second fixed sleeve and is connected to the driving member.

[0016] In some embodiments, the screw pump further includes a second bearing connected between the second fixing sleeve and the connecting shaft.

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

[0018] In some embodiments, the screw pump further comprises a coupling connected between the driving member and the connecting shaft.

[0019] In the screw pump of the embodiment of the present application, a second spiral chamber and a first spiral chamber are respectively formed on the inner and outer sides of the rotor, and the first spiral chamber and the second spiral chamber have opposite conveying directions of the fluid, 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.

[0020] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] One or more embodiments are exemplarily described by corresponding drawings, which do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and the figures in the drawings do not constitute proportional limitations unless otherwise stated.

[0022] Figure 1 is a cross-sectional view of a screw pump according to an embodiment of the present application; Figure 2 yes Figure 1 A partial enlarged view of the middle A; Figure 3 yes Figure 1 A partial enlarged view of point B in the middle; Figure 4 yes Figure 1 A partial enlarged view of point C in the middle.

[0023] The reference numerals in the specific implementation manner are as follows: 100. Screw pump; 1. External stator; 1a. First hollow section; 1b. Spiral section; 1c. Second hollow section; 101. First spiral inner wall; 102. First liquid passage cavity; 103. First suction port; 104. Liquid outlet cavity; 105. Sealing cavity; 2. rotor; 201. first spiral outer wall; 202. second spiral inner wall; 203. connecting part; 2031. third suction port; 3. inner stator; 301. second spiral outer wall; 4. Driving parts; 5. Inner cylinder; 501. Second liquid chamber; 6. Inner shaft; 7. First fixed sleeve; 8. First bearing; 9. First sealing ring; 10. Connecting sleeve; 1001. Liquid hole; 11. Second fixed sleeve; 12. Connecting shaft; 1201. Second suction port; 1202. Connecting groove; 13. Second bearing; 14. Second sealing ring; 15. Coupling; a, first spiral cavity; a1, first suction end; a2, first discharge end; b, second spiral chamber; b1, second suction end; b2, second discharge end. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. It should be noted that when an element is described as "fixed on" another element, it can be directly on another element, or there can be one or more centered elements therebetween. When an element is described as "connected" to another element, it can be directly connected to another element, or there can be one or more centered elements therebetween. It should be noted that, if there is no conflict, the various features in the embodiments of the present application can be combined with each other, all within the scope of protection of the present application. In addition, although the functional modules are divided in the device schematic diagram and the logical order is shown in the flow chart, in some cases, the steps shown or described can be performed in a different order from the module division in the device schematic diagram or the flow chart.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0026] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0027] In the description of the embodiments of the present application, the use of words such as "first" and "second" to define components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above words have no special meanings and therefore cannot be understood as limiting the scope of protection of the present application. In the description of the embodiments of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0028] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0029] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0030] See also Figure 1 The embodiment of the present application provides a screw pump 100 for conveying fluid, and the screw pump 100 includes an outer stator 1, a rotor 2, an inner stator 3 and a driving member 4. The outer stator 1 is provided with a first spiral inner wall 101. The rotor 2 is provided with a first spiral outer wall 201 and a second spiral inner wall 202. The outer stator 1 is sleeved outside the rotor 2, and a first spiral cavity a is formed between the first spiral outer wall 201 and the first spiral inner wall 101. The two ends of the first spiral cavity a are respectively provided with a first suction end a1 and a first discharge end a2. The inner stator 3 is provided with a second spiral outer wall 301, and the rotor 2 is sleeved outside the inner stator 3. The second spiral cavity b is formed between the second spiral outer wall 301 and the second spiral inner wall 202. The two ends of the second spiral cavity b are respectively provided with a second suction end b1 and a second discharge end b2, and the second suction end b1 is connected to the first discharge end a2. The driving member 4 is connected to the rotor 2, and the driving member 4 can drive the rotor 2 to rotate relative to the outer stator 1 and the inner stator 3 to input the external fluid from the first suction end a1 into the first spiral chamber a, and the fluid is output in sequence through the first discharge end a2, the second suction end b1, the second spiral chamber b and the second discharge end b2.

[0031] For the above outer stator 1, see Figure 1 The outer stator 1 is hollow and includes a first hollow section 1a, a spiral section 1b and a second hollow section 1c connected in sequence. The inner diameter of the first hollow section 1a and the inner diameter of the second hollow section 1c are both larger than the inner diameter of the spiral section 1b. The spiral section 1b is provided with a first suction end a1 at one end facing the first hollow section 1a, and a first discharge end a2 at one end facing the second hollow section 1c. The inner wall of the spiral section 1b is provided in a spiral shape to form a first spiral inner wall 101, and the rotor 2 is at least partially provided in the spiral section 1b.

[0032] In some embodiments, the outer stator 1 is configured as a double-layer structure, and the outer stator 1 includes an outer stator outer layer and an outer stator inner layer (not shown in the figure), the outer stator outer layer is coated on the outer stator inner layer, and the first spiral inner wall 101 is arranged on the outer stator inner layer. Among them, the outer stator outer layer is made of metal material, such as stainless steel material, galvanized alloy material, etc., to ensure the strength of the outer stator 1; the outer stator inner layer is made of flexible material, such as rubber, silicone, etc., to improve the deformable adaptability, thereby ensuring the sealing performance of the first spiral cavity a. It can be understood that in some other embodiments, the outer stator 1 can also be configured as a single-layer structure, such as only made of metal material, or only made of non-metallic material, which is not limited here.

[0033] For rotor 2 above, see Figure 1 The rotor 2 is hollow, the outer wall of the rotor 2 is spirally formed to form a first spiral outer wall 201, the inner wall of the rotor 2 is spirally formed to form a second spiral inner wall 202, and 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 is meshed with the first spiral inner wall 101.

[0034] In some embodiments, the rotor 2 is configured as a double-layer structure, including a rotor outer layer and a rotor inner layer (not shown in the figure), the rotor outer layer is coated on the outside of the rotor inner layer, the first spiral outer wall 201 is arranged on the rotor outer layer, and the second spiral inner wall 202 is arranged on the rotor inner layer. The rotor outer layer is made of metal material, such as stainless steel material, galvanized alloy material, etc., which can ensure the strength of the rotor 2; the rotor inner layer is made of rubber material to improve the deformable adaptability, thereby ensuring the sealing performance of the second spiral chamber b.

[0035] It is understandable that in some other embodiments, the rotor 2 may also be configured with an outer layer made of rubber material and an inner layer made of metal material. In some other embodiments, the rotor 2 may also be configured with a single-layer structure, such as being made of only metal material, or only non-metal material, which is not limited here.

[0036] For the inner stator 3 above, see Figure 1 , the inner stator 3 is roughly columnar, and the outer wall of the inner stator 3 is arranged in a spiral shape to form a second spiral outer wall 301, and the second spiral outer wall 301 is meshed with the second spiral inner wall 202. The second spiral outer wall 301 is provided with a second discharge end b2 at one end facing the first hollow section 1a, and the second spiral outer wall 301 is provided with a second suction end b1 at one end facing the second hollow section 1c. Among them, the inner stator 3 is configured to be non-rotatable relative to the outer stator 1, so that the rotor 2 can rotate simultaneously relative to the outer stator 1 and the inner stator 3. The inner stator 3 is made of metal material, such as stainless steel, galvanized alloy material, etc., to enhance the strength of the inner stator 3.

[0037] For the above-mentioned driving member 4, the driving member 4 is detachably mounted on the outer stator 1, and the output shaft of the driving member 4 is connected to the rotor 2, and the output shaft of the driving member 4 can drive the rotor 2 to rotate. Among them, the driving member 4 adopts a motor. It can be understood that in some other embodiments, the structure of the driving member 4 can be set according to actual needs, such as using a rotary cylinder, a rotary hydraulic cylinder, etc., which is not limited here.

[0038] It can be understood that the first spiral inner wall 101 and the first spiral outer wall 201 are designed to enclose a first spiral chamber 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 chamber a, so as to transport the fluid in the first spiral chamber 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 chamber b, so as to transport the fluid in the second spiral chamber b to the second discharge end b2.

[0039] It should be noted that in the embodiment of the present application, 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 spiral chamber a and the second spiral chamber b are opposite, that is, the thrust directions of the first spiral outer wall 201 and the second spiral inner wall 202 on the fluid are opposite, thereby greatly 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 antagonized by a thrust bearing, and the thrust bearing needs to be provided with a seal to isolate the lubricating oil and the pumped fluid, resulting in difficulty in heat dissipation of the thrust bearing. Therefore, a larger 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. In addition, the axial thrust causes the friction of the thrust bearing to increase, reduces the rotation speed of the rotor 2, and reduces the efficiency of the screw pump 100. The embodiment of the present 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. In addition, the friction of the thrust bearing is reduced, and the efficiency of the screw pump 100 is improved. Optionally, the screw pump 100 omits the thrust bearing, that is, adopts a radial bearing, which is conducive to reducing the cost of the screw pump 100.

[0040] In some embodiments, see Figure 1, the outer stator 1 is also provided with a first liquid passage cavity 102 and a first suction port 103. The first liquid passage cavity 102 is provided inside the first hollow section 1a, and the first suction port 103 is provided on the wall of the first hollow section 1a. The first suction port 103 connects the first liquid passage cavity 102 with the outside, and the first liquid passage cavity 102 is connected with 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 submerges the first suction port 103, so that the external fluid can be sucked into the first suction end a1. The number of the first suction ports 103 can be multiple, and the multiple first suction ports 103 are distributed at intervals.

[0041] In some embodiments, see Figure 1 The screw pump 100 further includes an inner cylinder 5, which is rotatably arranged in the first hollow section 1a of the outer stator 1, and a first liquid passage cavity 102 is formed between the inner cylinder 5 and the first hollow section 1a. Specifically, one end of the rotor 2 away from the driving 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 driving member 4, and the other end of the inner cylinder 5 is rotatably connected to the outer stator 1, and 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 cavity 501 is arranged inside the inner cylinder 5, and the second liquid passage cavity 501 is connected to the second discharge end b2. Among them, the inner cylinder 5 is made of a flexible material, such as a flexible metal, plastic or composite material, which can both produce deformation and withstand torque. When the screw pump 100 is working, the rotor 2 rotates eccentrically relative to the outer stator 1, so the inner cylinder 5 is set to a flexible material so that the inner cylinder 5 can produce deformation when rotating, avoid rigid impact, reduce noise and extend service life.

[0042] In some embodiments, see Figure 1 The screw pump 100 also includes an inner shaft 6, which is fixed in the inner tube 5, and a second liquid chamber 501 is formed between the inner shaft 6 and the inner tube 5. Specifically, one end of the inner stator 3 away from the driving 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 driving member 4; the other end of the inner shaft 6 extends to the outside of the inner tube 5, and the other end of the inner shaft 6 is fixedly connected to the outer stator 1, so that the outer stator 1 and the inner stator 3 are fixed. Among them, the inner shaft 6 is made of a flexible material, such as a flexible metal, plastic or composite material, which can both produce deformation and withstand torque. When the rotor 2 rotates relative to the inner stator 3, it will drive the inner stator 3 to displace in the circumferential direction. Therefore, the inner shaft 6 is set to a flexible material so that the inner stator 3 of the inner shaft 6 can be deformed when displaced in the circumferential direction, avoiding rigid impact, reducing noise and extending service life.

[0043] In some embodiments, see Figure 2The screw pump 100 further includes a first fixed sleeve 7, which is fixed in the outer stator 1, and the first fixed sleeve 7 is arranged 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 arranged in the first hollow section 1a, and the first fixed sleeve 7 is respectively sleeved outside the inner cylinder 5 and the inner shaft 6, and the first hollow section 1a, the inner cylinder 5 and the first fixed sleeve 7 are enclosed together to form the first liquid passage chamber 102.

[0044] In some embodiments, see Figure 2 The screw pump 100 further includes a first bearing 8, which is connected between the first fixed sleeve 7 and the inner cylinder 5. The inner cylinder 5 is rotatably connected to the first fixed sleeve 7 by the first bearing 8, which is conducive to reducing the friction between the inner cylinder 5 and the first fixed sleeve 7. In this embodiment, the first bearing 8 is a sliding copper sleeve. It is understandable that in some other embodiments, the first bearing can be set according to actual needs, such as being set to a ball bearing, a sliding bearing or a thrust bearing, which is not limited here.

[0045] In some embodiments, see Figure 2 The screw pump 100 further includes a first sealing ring 9, which is connected between the first fixed sleeve 7 and the inner tube 5. Specifically, the first sealing ring 9 is sleeved on the outer wall of the inner tube 5, the first sealing ring 9 abuts against the inner wall of the first fixed sleeve 7, and the first sealing ring 9 is arranged at an end of the first bearing 8 away from the first liquid chamber 102, so as to increase the sealing effect between the first fixed sleeve 7 and the inner tube 5.

[0046] In some embodiments, see Figure 1 and Figure 2 The outer stator 1 is further provided with a liquid outlet cavity 104, which is provided on the side of the first fixed sleeve 7 away from the first liquid passage cavity 102. Specifically, the liquid outlet cavity 104 is provided in the middle of the first hollow section 1a, and the interior of the first hollow section 1a is divided into the first liquid passage cavity 102 and the liquid outlet cavity 104. The liquid outlet cavity 104 is communicated with the second liquid passage cavity 501, and the fluid at the second discharge end b2 can be discharged to the liquid outlet cavity 104 through the second liquid passage cavity 501.

[0047] In some embodiments, see Figure 2The screw pump 100 further includes a connecting sleeve 10, which is connected between the first fixed sleeve 7 and the inner shaft 6. Specifically, a mounting groove is provided at one end of the first fixed sleeve 7 away from the first liquid passage chamber 102, and the connecting sleeve 10 is arranged in the mounting groove, and the connecting sleeve 10 is sleeved outside the inner shaft 6, so that the inner shaft 6 is fixedly connected to the first fixed sleeve 7. The connecting sleeve 10 is provided with a liquid passage hole 1001, and the liquid passage hole 1001 is connected to the liquid outlet chamber 104 and the second liquid passage chamber 501 respectively, and the fluid in the second liquid passage chamber 501 can be discharged to the liquid outlet chamber 104 through the liquid passage hole 1001. The number of the liquid passage holes 1001 can be multiple, and the multiple liquid passage holes 1001 are spaced around the central axis of the connecting sleeve 10.

[0048] In some embodiments, the connecting sleeve 10 is detachably arranged on the first fixed sleeve 7. When installing, the inner shaft 6 is first connected to the connecting sleeve 10, so as to facilitate the assembly and maintenance of the screw pump 100. The connecting sleeve 10 is annular, and the inner shaft 6 can be directly plugged into the connecting sleeve 10, so that it is not necessary to connect it through fasteners such as screws, which is conducive to improving the efficiency of disassembly and assembly between the inner shaft 6 and the connecting sleeve 10, and reducing the cost of the screw pump 100. The hole in the middle of the connecting sleeve 10 can be in a non-circular shape such as a square or a hexagon, and is adapted to the end of the inner shaft 6 plugged into the connecting sleeve 10, so that the inner shaft 6 can be prevented from rotating relative to the connecting sleeve 10. Similarly, the hole in the middle of the first fixed sleeve 7 can be in a non-circular shape such as a square or a hexagon, and is adapted to the contour of the connecting sleeve 10, so that the connecting sleeve 10 can be prevented from rotating relative to the first fixed sleeve 7.

[0049] In some embodiments, see Figure 1 One end of the outer stator 1 is also provided with a sealed cavity 105, which is connected to the first discharge end a2 and the second suction end b1. Specifically, the second hollow section 1c is provided with a sealed cavity 105 inside, and the fluid at the first discharge end a2 passes through the sealed cavity 105 and is sucked into the second spiral cavity b from the second suction end b1.

[0050] In some embodiments, see Figure 3 The screw pump 100 further includes a second fixing sleeve 11 fixed in the outer stator 1, and the second fixing sleeve 11 is arranged on the side of the sealing cavity 105 away from the first discharge end a2, and the end of the sealing cavity 105 is sealed by the second fixing sleeve 11. The second fixing sleeve 11 is detachably connected to the outer stator 1, which is convenient for maintenance and disassembly of the screw pump 100.

[0051] In some other embodiments, see Figure 1The screw pump 100 also includes a connecting shaft 12, which is at least partially disposed in the sealed cavity 105. The connecting shaft 12 is rotatably inserted into the second fixed sleeve 11, and the two ends of the connecting shaft 12 are respectively connected to the driving member 4 and the rotor 2. Specifically, the driving member 4 is connected to the end of the second hollow section 1c away from the spiral section 1b, and one end of the rotor 2 extends from the spiral section 1b into the sealed cavity 105. The output shaft of the driving member 4 is connected to one end of the connecting shaft 12, and the other end of the connecting shaft 12 passes through the second fixed sleeve 11 and extends to the sealed cavity 105 to connect with the rotor 2. By setting the connecting shaft 12, the driving member 4 outside the sealed cavity 105 can be connected to the rotor 2 to prevent the driving member 4 from contacting the fluid in the sealed cavity 105. Among them, the inner shaft 6 is made of a flexible material, such as flexible metal, plastic or composite material, which can both produce deformation and withstand torque.

[0052] In some embodiments, see Figure 4 The end of the connecting shaft 12 away from the driving member 4 is provided with a second suction port 1201, and the second suction port 1201 is connected to the sealing cavity 105 and the second suction end b1 respectively. The second suction port 1201 is close to the port of the rotor 2, so as to be connected to the second suction end b1 in the rotor 2. The number of the second suction ports 1201 can be multiple, and the multiple second suction ports 1201 are arranged at intervals along the circumference of the connecting shaft 12.

[0053] In some embodiments, see Figure 4 , a connecting portion 203 is provided at one end of the rotor 2, and a connecting groove 1202 is provided at one end of the connecting shaft 12, and the connecting portion 203 is inserted into the connecting groove 1202 to connect the rotor 2 to the connecting shaft 12. The connecting portion 203 is provided with a third suction port 2031, and the third suction port 2031 is communicated with the inside of the rotor 2, and the third suction port 2031 is directly opposite to the second suction port 1201 to communicate with the second suction port 1201. The number of the second suction ports 1201 and the third suction port 2031 is equal, and corresponds one to one, so as to increase the flow rate of the sealed cavity 105 flowing into the second suction end b1. Among them, the second suction port 1201 is provided at the groove wall of the connecting groove 1202, so as to communicate with the third suction port 2031 of the connecting portion 203, and communicate with the sealed cavity 105 outside the connecting shaft 12.

[0054] In some embodiments, see Figure 3The screw pump 100 further includes a second bearing 13, which is connected between the second fixed sleeve 11 and the connecting shaft 12. The connecting shaft 12 is rotatably connected to the second fixed sleeve 11 by the second bearing 13, which is conducive to reducing the friction between the connecting shaft 12 and the second fixed sleeve 11. In this embodiment, the second bearing 13 is a sliding copper sleeve. It is understandable that in some other embodiments, the structure of the second bearing 13 can be set according to actual needs, such as a ball bearing, a sliding bearing or a thrust bearing, etc., which is not limited here.

[0055] In some embodiments, see Figure 3 The screw pump 100 further includes a second sealing ring 14 , which is connected between the second fixing sleeve 11 and the connecting shaft 12 to increase the sealing effect between the second fixing sleeve 11 and the connecting shaft 12 .

[0056] In some embodiments, see Figure 3 The screw pump 100 further includes a coupling 15, which is connected between the driving member 4 and the connecting shaft 12. The coupling 15 is provided to facilitate installation and removal of the driving member 4.

[0057] In the screw pump 100 of the embodiment of the present application, a second spiral chamber b and a first spiral chamber a are respectively formed on the inner and outer sides of the rotor 2, and the first spiral chamber a and the second spiral chamber b have opposite conveying directions for the fluid, 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.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Under the concept of the present application, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of the present application as described above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A screw pump for conveying fluid, characterized in that: include: An outer stator is provided with a first spiral inner wall; The rotor is provided with a first spiral outer wall and a second spiral inner wall, the outer stator is sleeved outside the rotor, a first spiral cavity is formed between the first spiral outer wall and the first spiral inner wall, and two ends of the first spiral cavity are respectively provided with a first suction end and a first discharge end; The inner stator is provided with a second spiral outer wall, the rotor is sleeved outside the inner stator, a second spiral cavity is formed between the second spiral outer wall and the second spiral inner wall, a second suction end and a second discharge end are respectively provided at two ends of the second spiral cavity, and the second suction end is communicated with the first discharge end; A driving member is connected to the rotor, and the driving member can drive the rotor to rotate relative to the outer stator and the inner stator to input external fluid from the first suction end into the first spiral cavity, and the fluid is output through the first discharge end, the second suction end, the second spiral cavity and the second discharge end in sequence.

2. The screw pump according to claim 1, characterized in that: The outer stator is further provided with a first liquid passage cavity and a first suction port, wherein the first suction port connects the first liquid passage cavity with the outside, and the first liquid passage cavity is connected with 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 arranged in the outer stator, and one end of the inner cylinder is connected to one end of the rotor, the first liquid passage cavity is formed between the inner cylinder and the outer stator, and the inner cylinder is provided with a second liquid passage cavity, and the second liquid passage cavity is connected to the second discharge end.

4. The screw pump according to claim 3, characterized in that: The screw pump further includes an inner shaft fixed in the inner cylinder, one end of the inner shaft is connected to one end of the inner stator, and the second liquid passage cavity is formed between the inner shaft and the inner cylinder.

5. The screw pump according to claim 4, characterized in that: The screw pump further comprises a first fixing sleeve fixed in the outer stator, and the first fixing sleeve is arranged on a side of the first liquid passage chamber away from 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.

6. The screw pump according to claim 5, characterized in that: The outer stator is further provided with a liquid outlet cavity, and the liquid outlet cavity is provided on a side of the first fixed sleeve away from the first liquid passage cavity; The screw pump further comprises a connecting sleeve, wherein the connecting sleeve is connected between the first fixed sleeve and the inner shaft, and the connecting sleeve is provided with liquid holes, wherein the liquid holes are respectively connected with the liquid outlet cavity and the second liquid passage cavity.

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

8. The screw pump according to any one of claims 1 to 7, characterized in that: A sealed cavity is further provided at one end of the outer stator, and the sealed cavity is respectively connected to the first discharge end and the second suction end.

9. The screw pump according to claim 8, characterized in that The screw pump further comprises a connecting shaft, wherein the connecting shaft is at least partially disposed in the sealing cavity; The driving member is connected to one end of the outer stator, and two ends of the connecting shaft are respectively connected to the driving member and the rotor.

10. The screw pump according to claim 9, characterized in that A second suction port is provided at one end of the connecting shaft away from the driving member, and the second suction port is respectively connected to the sealing cavity and the second suction end.

11. The screw pump according to claim 9, characterized in that: The screw pump further comprises a second fixed sleeve fixed in the outer stator, and the second fixed sleeve is arranged on a side of the sealing cavity away from the first discharge end, and the connecting shaft is rotatably connected to the second fixed sleeve; The driving member is arranged on a side of the second fixing sleeve away from the sealing cavity, and one end of the connecting shaft passes through the second fixing sleeve and is connected to the driving member.

12. The screw pump according to claim 11, characterized in that The screw pump further comprises a second bearing, wherein the second bearing is connected between the second fixing sleeve and the connecting shaft; and / or The screw pump further comprises a second sealing ring, wherein the second sealing ring is connected between the second fixing sleeve and the connecting shaft; and / or The screw pump further comprises a coupling, which is connected between the driving member and the connecting shaft.

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