A coupling for a submersible progressing cavity pump

Abstract

The present invention belongs to the technical field of couplings for transmitting rotational motion, and particularly relates to a coupling for a submersible progressing cavity pump. The coupling includes a flexible rod, an output shaft connecting sleeve and a rotor connecting sleeve. The two ends of the flexible rod are respectively an output shaft connecting end and a rotor connecting end; both the output shaft connecting end and the rotor connecting end are provided with a stop portion, and a stop structure is provided on the protector output shaft or the output shaft connecting sleeve, and on the screw pump rotor or the rotor connecting sleeve. The stop portion and the stop structure are in circumferential stop cooperation; both the output shaft connecting end and the protector output shaft have external threads, and both ends of the output shaft connecting sleeve have internal threads. The output shaft connecting end and the protector output shaft are both threadedly connected to the output shaft connecting sleeve; both the rotor connecting end and the screw pump rotor have external threads, and both ends of the rotor connecting sleeve have internal threads. The rotor connecting end and the screw pump rotor are both threadedly connected to the rotor connecting sleeve. The connecting rotating device can withstand the alternating load of the complex motion of the screw pump and reduce the risk of failure.

Description

Technical Field

[0001] The present invention belongs to the technical field of couplings for transmitting rotational motion, and particularly relates to a coupling for a submersible progressing cavity pump. Background Art

[0002] A submersible progressing cavity pump unit for lifting fluids from deep wells usually consists of a series of interconnected modular components, including a motor, a protector, and a progressing cavity pump. Each part includes an external radial housing and an internal transmission shaft element, and the transmission shaft elements of different adjacent parts are connected to each other in a coupling assembly through some connecting devices. The conventional connecting device is a set of mating spline connections. During the operation of a conventional progressing cavity pump with spline connections, the motor drives various shaft elements to transmit power to the progressing cavity pump to transport fluids to the surface. The transmission shaft element rotates clockwise and the axial force points to the motor, thereby generating a compressive load transmitted by the transmission shaft element. The compressive load keeps the connection intact during the rotation of the shaft and splines; the thrust bearing in the protector can bear the axial force and protect the motor.

[0003] However, when the submersible progressing cavity pump is used in the application of coalbed methane drainage and gas production, in order to solve the problem of the difficulty in implementing gas and sand prevention measures caused by the equipment inlet being in the middle of the equipment, an inverted submersible progressing cavity pump structure is usually adopted. The axial force of this structure unit is a tensile load, and the spline connection will be separated and disengaged during the operation of the unit. A pin or a key is used at the connection to bear the tensile load to prevent the connection from disengaging. If a threaded connection is used, it will also disengage during reverse rotation. Both the spline or threaded structure need to add pins or keys to prevent the connection from disengaging. However, adding pins or keys requires drilling holes in the shaft, reducing the bearing area of the shaft and seriously reducing the mechanical properties and load-bearing capacity of the shaft. The rotor of the progressing cavity pump performs planetary motion, and a flexible rod must be used for the coupling of the submersible progressing cavity pump between the rotor and the output shaft of the submersible protector. The flexible rod is subjected to an eccentric torque and bears an alternating cyclic load. With the connection structure of pins or keys, fatigue fracture failure is very likely to occur.

[0004] Therefore, it is necessary to provide an improved technical solution to address the deficiencies of the above-mentioned existing technologies. Summary of the Invention

[0005] The purpose of the present invention is to provide a coupling for a submersible progressing cavity pump to at least solve problems such as shaft fracture caused by bending and alternating loads of units in inclined wells and horizontal wells.

[0006] To achieve the above purpose, the present invention provides the following technical solution:

[0007] A coupling for a submersible progressing cavity pump, the coupling is used to connect the rotor of the progressing cavity pump and the output shaft of the protector. The coupling includes a flexible rod, an output shaft connecting sleeve, and a rotor connecting sleeve. The two ends of the flexible rod are respectively an output shaft connecting end and a rotor connecting end;

[0008] Both the output shaft connection end and the rotor connection end are provided with stop portions. A stop structure is provided on the protector output shaft or the output shaft connecting sleeve, and a stop structure is provided on the screw pump rotor or the rotor connecting sleeve. The stop portions and the stop structures are in circumferential stop cooperation to prevent the flexible rod from rotating relative to the screw pump rotor and the protector output shaft.

[0009] External threads are provided on both the output shaft connection end and the protector output shaft. Internal threads are provided at both ends of the output shaft connecting sleeve. The output shaft connection end is threadedly connected to one end of the output shaft connecting sleeve, and the protector output shaft is threadedly connected to the other end of the output shaft connecting sleeve.

[0010] External threads are provided on both the rotor connection end and the screw pump rotor. Internal threads are provided at both ends of the rotor connecting sleeve. The rotor connection end is threadedly connected to one end of the rotor connecting sleeve, and the screw pump rotor is threadedly connected to the other end of the rotor connecting sleeve.

[0011] For the coupling for a submersible screw pump as described above, preferably, when the stop portion is a square, hexagonal, or octagonal shaft, the stop structure is a square, hexagonal, or octagonal hole.

[0012] When the stop portion is a square, hexagonal, or octagonal hole, the stop structure is a square, hexagonal, or octagonal shaft.

[0013] For the coupling for a submersible screw pump as described above, preferably, the front end of the protector output shaft is a hexagonal column, and an external thread structure is provided at the rear of the hexagonal column on the protector output shaft.

[0014] A hexagonal hole is provided at the end of the output shaft connection end. The hexagonal hole is used for plug-in cooperation with the hexagonal column at the front end of the protector output shaft. An external thread is provided around the hexagonal hole of the output shaft connection end.

[0015] Two sections of internal threads are axially provided inside the output shaft connecting sleeve. The internal thread at the front is in cooperation with the external thread on the protector output shaft, and the internal thread at the rear is in cooperation with the external thread on the output shaft connection end.

[0016] For the coupling for a submersible screw pump as described above, preferably, the coupling for a submersible screw pump further includes a pressure plate and a screw. A tapered surface that inclines inward is provided at the rear of the output shaft connection end on the flexible rod. The pressure plate is annular, and a tapered pressing surface is provided on the inner circumference of the pressure plate. The screw passes through the pressure plate and is threadedly connected to the output shaft connecting sleeve to press the pressing surface of the pressure plate against the tapered surface of the flexible rod.

[0017] The coupling for a submersible progressing cavity pump as described above. Preferably, the structure of the end of the rotor shaft is the same as that of the output shaft of the protector, the structure of the rotor connection end is the same as that of the output shaft connection end, and the structure of the rotor connection sleeve is the same as that of the output shaft connection sleeve.

[0018] The coupling for a submersible progressing cavity pump as described above. Preferably, the front section of the rotor of the progressing cavity pump has an external thread.

[0019] The end of the rotor connection end has an external thread, and a hexagonal shaft is provided in the front part of the external thread structure on the rotor connection end.

[0020] The rotor connection sleeve includes an upper connection sleeve and a lower connection sleeve. Two internal threads are axially provided inside the lower connection sleeve. The internal thread at the front is matched with the external thread of the rotor connection end, and the internal thread at the rear is matched with the external thread on the rotor of the progressing cavity pump.

[0021] The coupling for a submersible progressing cavity pump as described above. Preferably, a stepped shaft is provided on the outer wall at the front end of the lower connection sleeve, and a stepped hole is provided in the inner wall at the rear end of the upper connection sleeve. The stepped shaft on the lower connection sleeve is inserted into the stepped hole in the upper connection sleeve.

[0022] The coupling for a submersible progressing cavity pump as described above. Preferably, the upper connection sleeve and the lower connection sleeve are welded and connected at the place where their outer walls are in contact with each other.

[0023] The coupling for a submersible progressing cavity pump as described above. Preferably, the lower connection sleeve and the rotor of the progressing cavity pump are welded and connected at the place where their outer walls are in contact with each other.

[0024] The coupling for a submersible progressing cavity pump as described above. Preferably, the material of the flexible rod is titanium alloy.

[0025] Beneficial effects:

[0026] The connection and rotation device of the present invention has a simple structure, is convenient for assembly and disassembly, and is easy for on-site installation. The connection and rotation device is connected to the protector output shaft and the screw pump rotor by setting a threaded structure and a hexagonal hole or hexagonal shaft structure. Among them, the hexagonal hole or hexagonal shaft connection structure can transmit a large torque without causing the flexible rod to break; the threaded structure prevents the shaft from separating and disengaging. On this basis, the present invention sets a pressure plate and screws, or a welding method to further ensure the firm and reliable connection of the coupling for the submersible screw pump with the protection shaft and the rotor; compared with the method of setting pins or keys in the prior art, the coupling for the submersible screw pump of the present invention does not damage the cross-sectional structure of the shaft, the flexible rod has a high strength, can withstand the alternating load generated by the complex movement of the screw pump, prevent the flexible rod from breaking, and reduce the risk of the unit malfunctioning. By setting a connecting sleeve to cooperate with the flexible rod to connect with the protector output shaft and the screw pump rotor, the problem that titanium alloy and alloy steel are not easy to weld is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 FIG. is a schematic connection diagram of the coupling for the submersible screw pump in the embodiment of the present invention;

[0028] Figure 2 FIG. is a schematic structural diagram of the output shaft connection end of the flexible rod in the embodiment of the present invention;

[0029] Figure 3 FIG. is a schematic structural diagram of the rotor connection end of the flexible rod in the embodiment of the present invention;

[0030] Figure 4 FIG. is a partial enlarged view of the pressure plate and screws in the embodiment of the present invention.

[0031] In the figure: 1. Protector output shaft; 2. Output shaft connecting sleeve; 3. Pressure plate; 4. Screw; 5. Flexible rod; 6. Upper connecting sleeve; 7. Lower connecting sleeve; 8. Screw pump rotor; 51. First external thread; 52. Hexagonal hole; 53. Hexagonal shaft; 54. Second external thread. DETAILED DESCRIPTION OF THE INVENTION

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0033] In the description of the present invention, the orientation or positional relationship indicated by the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and does not require the present invention to be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. The terms "connected" and "coupled" used in the present invention should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be directly connected or indirectly connected through an intermediate component. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0034] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0035] According to a specific embodiment of the present invention, as Figures 1-4 shown, the present invention provides a coupling for a submersible progressing cavity pump. The coupling for the submersible progressing cavity pump can be used in a submersible progressing cavity pump unit or other types of submersible oil pump units.

[0036] The coupling is used to connect the rotor 8 of the progressing cavity pump and the output shaft 1 of the protector. The coupling includes a flexible rod 5, an output shaft connecting sleeve 2, and a rotor connecting sleeve. The two ends of the flexible rod 5 are respectively an output shaft connecting end and a rotor connecting end. The direction from the output shaft connecting end to the rotor connecting end of the flexible rod 5 is defined as the front-rear direction.

[0037] Both the output shaft connecting end and the rotor connecting end are provided with a stop portion. A stop structure is provided on the output shaft 1 of the protector or the output shaft connecting sleeve 2, and a stop structure is provided on the rotor 8 of the progressing cavity pump or the rotor connecting sleeve. The stop portion and the stop structure are in circumferential stop cooperation to prevent the flexible rod 5 from rotating relative to the rotor 8 of the progressing cavity pump and the output shaft 1 of the protector. External threads are provided on both the output shaft connecting end and the output shaft 1 of the protector. Two sections of internal threads are provided on the output shaft connecting sleeve 2 in the front-rear direction. The output shaft connecting end is threadedly connected to one end of the output shaft connecting sleeve 2, and the output shaft 1 of the protector is threadedly connected to the other end of the output shaft connecting sleeve 2. External threads are provided on both the rotor connecting end and the rotor 8 of the progressing cavity pump. Two sections of internal threads are provided on the rotor connecting sleeve in the front-rear direction. The rotor connecting end is threadedly connected to one end of the rotor connecting sleeve, and the rotor 8 of the progressing cavity pump is threadedly connected to the other end of the rotor connecting sleeve. By providing a stop structure to transmit torque circumferentially and a threaded connection structure to prevent the flexible rod 5 from separating from the output shaft and the rotor axially, the coupling for the submersible progressing cavity pump can be more firmly and stably connected between the output shaft 1 of the protector and the rotor 8 of the progressing cavity pump, and can stably transmit the acting force.

[0038] When the blocking part is a square, hexagonal, or octagonal shaft, the blocking structure is a square, hexagonal, or octagonal hole; when the blocking part is a square, hexagonal, or octagonal hole, the blocking structure is a square, hexagonal, or octagonal shaft. In this embodiment, the blocking part on the output shaft connection end adopts a hexagonal hole 52 structure, and the blocking part on the rotor connection end adopts a hexagonal shaft 53 structure. Whether it is the hexagonal hole 52 or the hexagonal shaft 53, its own shape is an axisymmetric structure with a uniform structure, which can withstand a large torque and prevent the flexible rod 5 from breaking. In other embodiments, the blocking part can also adopt a shaft or hole structure with multiple sides such as triangular, square, and octagonal.

[0039] The front end of the protector output shaft 1 is a hexagonal column, and an external thread structure is provided at the rear of the hexagonal column on the protector output shaft 1; a hexagonal hole 52 is provided at the end of the output shaft connection end, and the hexagonal hole 52 is used for plug-in cooperation with the hexagonal column at the front end of the protector output shaft 1. A first external thread 51 is provided on the periphery of the hexagonal hole 52 at the output shaft connection end; two internal threads are axially provided inside the output shaft connecting sleeve 2. The internal thread at the front is matched with the external thread on the protector output shaft 1, and the internal thread at the rear is matched with the first external thread 51 on the output shaft connection end.

[0040] The inside of the output shaft connecting sleeve 2 is a stepped hole structure. The diameter of the internal thread at the front inside the output shaft connecting sleeve 2 is smaller than the diameter of the internal thread at the rear. The pitch of the internal thread at the front is the same as that of the internal thread at the rear. The output shaft connecting sleeve 2 is installed from front to back.

[0041] The coupling for the submersible progressing cavity pump further includes a pressure plate 3 and a screw 4. The rear part of the output shaft connection end on the flexible rod 5 has an inwardly inclined conical surface. The pressure plate 3 is annular, and the inner circumference of the pressure plate 3 has a conical pressing surface. The screw 4 passes through the pressure plate 3 and is threadedly connected to the output shaft connecting sleeve 2 to press the pressing surface of the pressure plate 3 against the conical surface of the flexible rod 5.

[0042] The pressure plate 3 presses against the end face of the output shaft connecting sleeve 2 from back to front. The pressure plate 3 is provided with a through hole through which the screw 4 passes. By tightening the screw 4, the pressure plate 3 is pressed against the rear end face of the output shaft connecting sleeve 2, and the pressing surface and the conical surface on the flexible rod 5 are blocked from each other in the front-rear direction. Through the arrangement of the pressure plate 3 and the screw 4, it is possible to prevent the threaded connections between the output shaft connecting sleeve 2, the protector output shaft 1, and the flexible rod 5 from loosening and ensure the firm and reliable connection.

[0043] The front section of the progressing cavity pump rotor 8 is an external thread; the end of the rotor connection end is a second external thread 54, and a hexagonal shaft 53 is provided in front of the second external thread 54 on the rotor connection end; the rotor connecting sleeve includes an upper connecting sleeve 6 and a lower connecting sleeve 7. Two internal threads are axially provided inside the lower connecting sleeve 7. The internal thread at the front is matched with the second external thread 54 on the rotor connection end, and the internal thread at the rear is matched with the external thread on the progressing cavity pump rotor 8.

[0044] A stepped shaft is provided on the outer wall at the front end of the lower connecting sleeve 7, and a stepped hole is provided in the inner wall at the rear end of the upper connecting sleeve 6. The stepped shaft on the lower connecting sleeve 7 is inserted into the stepped hole in the upper connecting sleeve 6.

[0045] Since there is only an external thread structure on the screw pump rotor 8 and no hexagonal structure, by providing two connecting sleeves, among which the upper connecting sleeve 6 has a hexagonal hole 52 and the lower connecting sleeve 7 has internal threads at both ends, the flexible rod 5 is connected to the screw pump rotor 8. That is, through the transfer of the upper connecting sleeve 6 and the lower connecting sleeve 7, two external thread structures and a hexagonal shaft 53 structure are firmly connected together.

[0046] The upper connecting sleeve 6 and the lower connecting sleeve 7 are welded and connected at the place where their outer walls are in contact with each other; the lower connecting sleeve 7 and the screw pump rotor 8 are welded and connected at the place where their outer walls are in contact with each other. By welding and connecting, the loosening of the threaded connection between the lower connecting sleeve 7, the screw pump rotor 8 and the flexible rod 5 is avoided, ensuring the reliability of the connection.

[0047] In other embodiments, the structure of the end of the rotor shaft is the same as that of the output shaft 1 of the protector, the structure of the rotor connection end is the same as that of the output shaft connection end, and the structure of the rotor connecting sleeve is the same as that of the output shaft connecting sleeve 2. With such a setting, the structure of the flexible rod 5 is symmetrically the same at both ends, and the welding process can be reduced, making assembly and disassembly more convenient.

[0048] The material of the flexible rod 5 is titanium alloy. In this application, the flexible rod 5 is used in cooperation with the output shaft connecting sleeve 2 and the rotor connecting sleeve to connect the output shaft 1 of the protector and the screw pump rotor 8, without welding the flexible rod 5 to the output shaft 1 of the protector and the screw pump rotor 8 (the material of which is alloy steel), solving the problem that titanium alloy and alloy steel are not easy to weld.

[0049] In summary, the connection and rotation device of the present invention has a simple structure, is convenient for assembly and disassembly, and is convenient for on-site installation. The connection and rotation device is connected to the output shaft of the protector and the screw pump rotor by setting a threaded structure and a structure of a hexagonal hole or a hexagonal shaft. Among them, the hexagonal hole or hexagonal shaft connection structure can transmit a large torque, while the threaded structure prevents the shaft from separating and disengaging. The coupling for the submersible screw pump of the present invention can withstand the alternating load generated by the complex movement of the screw pump, prevent the flexible rod from breaking, and reduce the risk of the unit malfunctioning.

[0050] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are within the scope of the claims of the present invention awaiting approval.

Claims

1. A coupling for a submersible progressing cavity pump, which is used to connect the rotor of the progressing cavity pump and the output shaft of the protector. Characterized in that, The coupling includes a flexible rod, an output shaft connecting sleeve and a rotor connecting sleeve. The two ends of the flexible rod are respectively an output shaft connecting end and a rotor connecting end; Both the output shaft connecting end and the rotor connecting end are provided with a stop portion. A stop structure is provided on the protector output shaft or the output shaft connecting sleeve, and a stop structure is provided on the progressing cavity pump rotor or the rotor connecting sleeve. The stop portion and the stop structure are in circumferential stop cooperation to prevent the flexible rod from rotating relative to the progressing cavity pump rotor and the protector output shaft; External threads are provided on both the output shaft connecting end and the protector output shaft. Internal threads are provided at both ends of the output shaft connecting sleeve. The output shaft connecting end is threadedly connected to one end of the output shaft connecting sleeve, and the protector output shaft is threadedly connected to the other end of the output shaft connecting sleeve; External threads are provided on both the rotor connecting end and the progressing cavity pump rotor. Internal threads are provided at both ends of the rotor connecting sleeve. The rotor connecting end is threadedly connected to one end of the rotor connecting sleeve, and the progressing cavity pump rotor is threadedly connected to the other end of the rotor connecting sleeve. When the stop portion is a square, hexagon, or octagon shaft, the stop structure is a square, hexagon, or octagon hole; When the stop portion is a square, hexagon, or octagon hole, the stop structure is a square, hexagon, or octagon shaft. The front end of the protector output shaft is a hexagon column, and an external thread structure is provided at the rear of the hexagon column on the protector output shaft; A hexagon hole is provided at the end of the output shaft connecting end. The hexagon hole of the output shaft connecting end is used for plug-in cooperation with the hexagon column at the front end of the protector output shaft. An external thread is provided on the periphery of the hexagon hole of the output shaft connecting end; Two sections of internal threads are axially provided inside the output shaft connecting sleeve. The internal thread at the front is matched with the external thread on the protector output shaft, and the internal thread at the rear is matched with the external thread on the output shaft connecting end. The coupling for the submersible progressing cavity pump further includes a pressure plate and a screw. The rear part of the output shaft connecting end on the flexible rod has an inwardly inclined conical surface. The pressure plate is annular, and the inner circumference of the pressure plate has a conical pressing surface. The screw passes through the pressure plate and is threadedly connected to the output shaft connecting sleeve to press the pressing surface of the pressure plate against the conical surface of the flexible rod; The front section of the progressing cavity pump rotor is an external thread; The end of the rotor connecting end is an external thread, and the front part of the external thread structure on the rotor connecting end is a hexagon shaft; The rotor connecting sleeve includes an upper connecting sleeve and a lower connecting sleeve. Two sections of internal threads are axially provided inside the lower connecting sleeve. The internal thread at the front is matched with the external thread on the rotor connecting end, and the internal thread at the rear is matched with the external thread on the progressing cavity pump rotor.

2. The coupling for a submersible progressing cavity pump according to claim 1, Characterized in that, The end structure of the progressing cavity pump rotor is the same as that of the protector output shaft, the structure of the rotor connecting end is the same as that of the output shaft connecting end, and the structure of the rotor connecting sleeve is the same as that of the output shaft connecting sleeve.

3. The coupling for a submersible progressing cavity pump according to claim 1, characterized in that, a stepped shaft is provided on the outer wall of the front end of the lower connecting sleeve, a stepped hole is provided in the inner wall of the rear end of the upper connecting sleeve, and the stepped shaft on the lower connecting sleeve is inserted into the stepped hole in the upper connecting sleeve.

4. The coupling for a submersible progressing cavity pump according to claim 1, characterized in that, the upper connecting sleeve and the lower connecting sleeve are welded and connected at the place where their outer walls are in contact with each other.

5. The coupling for a submersible progressing cavity pump according to claim 1, characterized in that, the lower connecting sleeve and the rotor of the progressing cavity pump are welded and connected at the place where their outer walls are in contact with each other.

6. The coupling for a submersible progressing cavity pump according to any one of claims 1-5, characterized in that, the flexible rod is made of titanium alloy.

Images