Screw motor

Abstract

The invention provides a screw motor. The screw motor comprises a stator and a rotor; wherein the stator comprises a stator shell and a stator cavity, a spiral cavity channel is arranged in the cavity, the contour line of the stator cavity is a petal-shaped line formed by sequentially connecting a plurality of groups of convex first arc sections and concave second arc sections end to end, and arc-shaped transition sections are arranged between the first arc sections and the second arc sections; the stator is arranged on the rotor in a sleeved mode, and the outer surface of the stator is matched with the inner surface of the spiral cavity channel. According to the screw motor provided by the invention, the arc-shaped transition section is arranged at the position where interference is possibly generated in the stator cavity, so that interference between the stator and the rotor is reduced, and meanwhile, the sealing performance of a cavity formed between the stator and the rotor when the screw drill works is ensured to the greatest extent.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas mining engineering machinery, and in particular to a screw motor. Background Art

[0002] The ultra-deep layers of 10,000 meters in my country's Tarim, Sichuan, Junggar and other basins have huge oil and gas potential. With the exploration and development of deeper strata and the understanding of their geological characteristics, higher requirements are placed on the extreme performance of drilling tools.

[0003] In the process of drilling the formation, the main equipment used is the screw drill. The stator cavity lining of the traditional screw drill is made of rubber, which has an interference fit with the rotor. During the operation of the screw motor, the interference between the stator and the rotor is eliminated by the deformation of the rubber lining in the stator cavity, so that the screw drill can operate normally. However, as the operation time increases, the rubber lining gradually ages and becomes damaged, which eventually leads to jamming or leakage during the operation of the screw motor.

[0004] In addition, as the drilling depth increases, the temperature of the deep well may reach 300 degrees Celsius and the pressure may exceed 150MPa, which also puts higher requirements on the performance of the screw drill. In this environment, the rubber parts of the screw drill with rubber lining will gradually deform and decompose, eventually causing the screw motor to fail. Therefore, only all-metal screw motors can be used for deep well drilling. Since the metal rotor and metal stator parts cannot be fitted by interference, only clearance fit can be adopted. However, since the motor line of the metal screw motor is the inner and outer cycloid line, interference will still occur between the stator and the rotor during operation, causing jamming and leakage. Finally, the internal water power of the screw motor is insufficient, which delays the drilling progress.

[0005] In summary, there is an urgent need to improve the screw motor to further reduce the adverse effects of mutual interference between the stator and the rotor. Summary of the invention

[0006] In view of the problems in the prior art, an embodiment of the present invention provides a screw motor, which can at least partially solve the problems in the prior art.

[0007] In one aspect, the present invention provides a screw motor, comprising: a stator and a rotor;

[0008] The stator comprises a stator housing and a stator cavity, wherein a spiral cavity is arranged in the cavity, wherein the contour line of the stator cavity is a petal-shaped line formed by connecting multiple groups of first convex circular arc segments and second concave circular arc segments end to end in sequence, and an arc-shaped transition section is arranged between the first circular arc segment and the second circular arc segment;

[0009] The stator is sleeved on the rotor, and the outer surface of the stator matches the inner surface of the spiral cavity.

[0010] Furthermore, the stator cavity is made of rubber material.

[0011] Furthermore, the stator and the rotor are interference fit.

[0012] Furthermore, the stator cavity is made of metal and is integrally formed with the stator housing.

[0013] Furthermore, the stator and the rotor are clearance-fitted.

[0014] Furthermore, the first arc segment and the second arc segment have a first equidistant radius relative to the contour line of the stator, and the arc-shaped transition segment has a second equidistant radius relative to the contour line of the stator, and the second equidistant radius is greater than the first equidistant radius.

[0015] Furthermore, the position of the arc-shaped transition section corresponds to the position of the buckle line on the contour line of the stator.

[0016] Furthermore, the starting and ending positions of the arc-shaped transition section correspond to the starting and ending positions of the buckle line.

[0017] On the other hand, the present invention further provides a screw drilling tool, comprising: an anti-drop assembly, a screw motor according to any one of the aforementioned embodiments, a universal joint, and a transmission shaft connected in sequence.

[0018] In another aspect, the present invention further provides a method for optimizing a stator cavity contour of a screw motor, comprising:

[0019] Obtain the cycloid shape of the stator cavity;

[0020] Based on the cycloid line shape and a preset first equidistant radius, drawing an equidistant curve of the cycloid line shape;

[0021] Acquire position information of a buckle line on the equidistant curve, wherein the position information includes a start and end position of the buckle line on the equidistant curve;

[0022] The position to be optimized on the stator cavity is determined based on the position information, and the contour line of the position to be optimized is optimized.

[0023] The screw motor provided by the embodiment of the present invention sets an arc transition section at a position in the stator cavity where interference may occur, thereby reducing the interference between the stator and the rotor, and at the same time ensuring the sealing of the chamber formed between the stator and the rotor when the screw drill is working to the greatest extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0025] Figure 1 It is a schematic diagram of the structure of a screw drill provided in one embodiment of the present invention.

[0026] Figure 2 A schematic diagram of the anti-drop assembly structure provided in an embodiment of the present invention.

[0027] Figure 3 A schematic structural diagram of a screw motor provided in an embodiment of the present invention.

[0028] Figure 4 This is a schematic diagram of the end surface line of the screw motor stator provided in an embodiment of the present invention.

[0029] Figure 5 A schematic diagram of the cycloid line shape and the corresponding equidistant curve of the screw motor stator provided in an embodiment of the present invention.

[0030] Figure 6 A schematic diagram of the position of the buckle line provided in an embodiment of the present invention.

[0031] Figure 7 A schematic flow chart of a method for optimizing the stator cavity contour of a screw motor provided in an embodiment of the present invention.

[0032] Figure 8 A schematic structural diagram of a universal joint provided in an embodiment of the present invention.

[0033] Fig. 9 This is a schematic diagram of the transmission shaft structure provided by an embodiment of the present invention.

[0034] Fig.10 A schematic diagram of a ring structure provided in an embodiment of the present invention.

[0035] Fig.11 A schematic structural diagram of an inner sleeve provided in an embodiment of the present invention.

[0036] Fig.12 A schematic structural diagram of an upper spacer sleeve assembly provided in an embodiment of the present invention.

[0037] Fig.13 A schematic structural diagram of a PDC thrust bearing provided in an embodiment of the present invention.

[0038] Fig.14 A schematic structural diagram of a bearing outer ring provided in an embodiment of the present invention.

[0039] Fig.15 A schematic structural diagram of a bearing inner ring provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention more clear, the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention. It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other arbitrarily.

[0041] Figure 1 Schematic diagram of the screw drill structure provided by an embodiment of the present invention. Figure 1 As shown, the screw drill provided by the embodiment of the present invention comprises: an anti-drop assembly 1, a screw motor 2, a universal shaft 3 and a transmission shaft 4 which are connected in sequence.

[0042] Specifically, Figure 1 As shown, the screw drill provided by the embodiment of the present invention comprises an anti-drop assembly 1, a screw motor 2, a universal shaft 3 and a transmission shaft 4 which are connected in sequence. The upper end of the rotor in the screw motor is connected to the anti-drop assembly 1. The drilling fluid enters through the anti-drop assembly 1 under the action of the high-pressure pump group on the ground. As the drilling fluid pressure increases, the rotor of the screw motor is driven to perform planetary motion in the stator. The lower end of the rotor is connected to the universal shaft 3, which converts the planetary motion of the rotor into fixed axis motion, transmits the power output to the transmission shaft 4, and drives the screw drill to operate.

[0043] Figure 2 A schematic diagram of the anti-drop assembly structure provided by an embodiment of the present invention, such as Figure 2 As shown, on the basis of the above-mentioned embodiments, the anti-drop assembly 1 further includes an upper end joint (1-1), a lock nut (1-2), a chuck (1-3) and a tension joint (1-4). The screw drill provided in the embodiment of the present invention does not use a bypass valve assembly, but uses a conversion joint to connect the all-metal screw drill with the drill pipe. The drilling fluid is pumped into the anti-drop assembly 1 through the ground high-pressure pump group. As the ground pump pressure continues to increase, the drilling fluid flows into the screw motor 2, and the screw motor rotates.

[0044] Figure 3 A schematic diagram of the structure of a screw motor provided in an embodiment of the present invention, Figure 4 The end surface line diagram of the screw motor stator provided by the embodiment of the present invention is as follows: Figure 3 Figure 4As shown, on the basis of the above embodiments, further, the screw motor 2 includes: a rotor (2-1) and a stator (2-2); the stator (2-2) includes a stator housing (2-2-1) and a stator cavity (2-2-2), a spiral cavity is arranged in the stator cavity (2-2-2), and the contour line of the stator cavity (2-2-2) is a petal-shaped line formed by connecting multiple groups of convex first arc segments 2a and concave second arc segments 2b in sequence, and an arc-shaped transition segment 2c is arranged between the first arc segment 2a and the second arc segment 2b;

[0045] The convexity of the first arc segment 2a is a protrusion in the centrifugal direction of the stator inner cavity, and correspondingly, the concavity of the second arc segment 2b is a depression in the centripetal direction of the stator inner cavity.

[0046] The stator (2-2) is sleeved on the rotor (2-1), and the outer surface of the stator (2-2) matches the inner surface of the spiral cavity.

[0047] In traditional screw drills, the stator cavity is made of rubber, and the fitting relationship between it and the rotor is an interference fit. However, in order to ensure the sealing of the screw motor cavity, the rotor in the existing design will interfere with the stator cavity when performing planetary motion in the stator cavity. However, since the stator cavity is made of rubber, smaller interference can be offset by the elasticity of the rubber. However, such a setting cannot effectively eliminate interference when faced with larger interference, and will also aggravate the wear and aging of the rubber cavity.

[0048] At the same time, with the exploration and exploitation of resources in deeper formations, the working depth of screw drills has also increased. When operating in deeper formations, the temperature may be as high as 300 degrees Celsius and the pressure may exceed 150MPa, which has a great impact on the screw drill itself. The first thing to be affected is the stator cavity made of rubber. Under high temperature and high pressure environment, the stator cavity that continues to work will deform and decompose faster, eventually leading to the failure of the screw motor. The current solution is mainly to replace the rubber stator with a full metal stator to prevent its deformation under high temperature and high pressure environment. However, since the stator and rotor are both made of metal at this time, their matching relationship can only be clearance matching. However, even so, the linear shape of the screw motor movement is still the inner and outer cycloid linear shape. During operation, there is still interference and jamming between the stator and the rotor. At this time, there is no longer a stator cavity made of rubber material that can offset all or part of the interference through deformation, resulting in jamming or leakage between the metal stator and the metal rotor, which ultimately leads to insufficient water power in the screw motor.

[0049] In summary, whether it is a metal stator or a rubber stator, interference will occur when it cooperates with the rotor. Therefore, an embodiment of the present invention provides a screw motor, and an arc-shaped transition section is arranged at the position where interference occurs in the stator cavity to reduce the interference between the stator and the rotor, while at the same time ensuring to the greatest extent the sealing of the chamber formed between the stator and the rotor when the screw drill is working.

[0050] On the basis of the above embodiments, further, the stator cavity (2-2-2) is made of rubber material.

[0051] Specifically, the stator (2-2) comprises a stator shell (2-2-1) and a stator cavity (2-2-2); the stator cavity (2-2-2) is a cylindrical rubber sleeve made of rubber integrally molded, a spiral cavity is formed at the center, and the outer wall of the stator cavity (2-2-2) is in contact with the inner wall of the stator shell.

[0052] When the stator cavity (2-2-2) is made of rubber, since the rubber itself has a certain elasticity, the stator (2-2) and the rotor (2-1) are in an interference fit.

[0053] On the basis of the above-mentioned embodiments, further, the stator cavity (2-2-2) is made of metal and is integrally formed with the stator housing (2-2-1).

[0054] Since the stator (2-2) and the rotor (2-1) are metal-to-metal fit, and metal does not have elasticity, the stator (2-2) and the rotor (2-1) are clearance fit.

[0055] In order to ensure that there is a gap between the stator and the rotor while ensuring the sealing performance when the stator and the rotor are matched, preferably, the gap can be 0.3mm, 0.5mm, or 1.0mm.

[0056] Figure 4 The end surface line diagram of the screw motor stator provided by the embodiment of the present invention is as follows: Figure 4 As shown, on the basis of the above embodiments, further, the first arc segment 2a and the second arc segment 2b have a first equidistant radius relative to the contour line of the stator, and the arc transition segment 2c has a second equidistant radius relative to the contour line of the stator cavity, and the second equidistant radius is greater than the first equidistant radius.

[0057] Specifically, the end surface line shape of the existing screw motor stator is a petal-shaped line shape formed by connecting multiple groups of convex first arc segments 2a and concave second arc segments 2b, but no arc transition segment 2c is set between the first arc segment 2a and the second arc segment 2b.

[0058] Figure 5 The cycloid line shape and the corresponding equidistant curve diagram of the screw motor stator provided in the embodiment of the present invention are as follows: Figure 5 As shown, the star-shaped curve on the inside is a cycloid curve (5-1) of a screw motor stator, and the petal-shaped curve outside the cycloid curve (5-1) is its corresponding equidistant curve (5-2). The equidistant curve (5-2) is also the contour line of the screw motor stator cavity.

[0059] exist Figure 5 In the case shown, the distances from points on the cycloid line (5-1) of the screw motor stator to corresponding points on the equidistant curve (5-2) are equal, and are both first equidistant radii. The first equidistant radius is selected and set according to actual needs to ensure that the interference between the stator and the rotor is minimized, while the sealed chamber formed by the stator and the rotor during operation also has good sealing properties. This embodiment is not specifically limited here.

[0060] Based on the cycloid line shape (5-1) of the screw motor stator and the equidistant curve (5-2) drawn according to the first equidistant radius selected as needed, as shown in Figure 5 As shown, the equidistant curve (5-2) forms a corresponding buckle line (5-3) at the position between the first arc segment 2a and the second arc segment 2b.

[0061] The fundamental reason for the buckle line (5-3) is that the normal lines of any two adjacent points on the cycloid intersect within the equidistant radius. The stator produced at this time is not a strict cycloid equidistant curve. In other words, when the rotor performs planetary motion in the stator, interference will occur at the position corresponding to the buckle line (5-3), resulting in wear, jamming or leakage.

[0062] Based on the above situation, the present invention sets an arc transition section 2c for the position shown on the contour line of the screw motor stator cavity that will interfere with the rotor. Since the buckle line (5-3) is formed at the corresponding position between the first arc section 2a and the second arc section 2b on the equidistant curve (5-2), the arc transition section 2c is set between the first arc section 2a and the second arc section 2b in the contour line of the screw motor stator cavity.

[0063] Since the position of the buckle line (5-3) corresponds to the contour line of the screw motor stator cavity, interference will occur during the rotation of the rotor, so it is necessary to slightly increase the distance between it and the rotor when it runs to this position. For the arc-shaped transition section 2c, the equidistant radius between any point on it and the cycloid line (5-1) of the screw motor stator is increased, that is, the arc-shaped transition section 2c has a second equidistant radius relative to the contour line of the stator cavity, and the second equidistant radius is larger than the first equidistant radius.

[0064] On the basis of the above-mentioned embodiments, further, the position of the arc-shaped transition section 2c corresponds to the position of the buckle line (5-3) on the contour line of the stator cavity.

[0065] Preferably, the starting and ending positions of the arc-shaped transition section 2c correspond to the starting and ending positions of the buckle line (5-3).

[0066] Figure 6 A schematic diagram of the position of the buckle line provided in an embodiment of the present invention, such as Figure 6 As shown, the curve where points A and B are located is the cycloid of the screw motor stator. Points C and D are the equidistant points of points A and B on the equidistant curve, respectively, and the equidistant radius is r. a .from Figure 6 It can be seen that the point D, which is equidistant from point B, has a loop, resulting in the formation of a buckle line between points C and D.

[0067] Since points C and D correspond to points A and B respectively, a buckle line is formed between points C and D, corresponding to the arc-shaped transition section 2c. That is to say, points C and D are the starting point and end point of a buckle line. When the arc-shaped transition section 2c on the contour line of the screw motor stator cavity corresponds to the buckle line, the starting and end point positions of the arc-shaped transition section 2c also correspond to the starting point and end point of the buckle line.

[0068] Figure 7 A schematic diagram of a process flow of a screw motor stator cavity contour optimization method provided by an embodiment of the present invention, such as Figure 7 As shown, the method includes:

[0069] S101: Obtaining a cycloid line shape of a stator cavity;

[0070] When it is necessary to optimize the contour line of a specific screw motor stator cavity to reduce the interference between the stator and the rotor, the cycloid line shape of the stator cavity is firstly obtained.

[0071] S102: Drawing an equidistant curve of the cycloid line shape based on the cycloid line shape and a preset first equidistant radius;

[0072] The cycloid line of the stator is also called the stator bone line. Its equidistant curve refers to the outer envelope of a series of circles with the center on the stator bone line and the radius as the first equidistant radius. The distance from each point on it to the corresponding point on the stator bone line is the first equidistant radius.

[0073] Regarding the first equidistant radius, it is selected and set according to actual needs to ensure that the interference between the stator and the rotor is minimized, while the sealed chamber formed by the stator and the rotor during operation also has good sealing performance. This embodiment does not make any specific limitations here.

[0074] S103: Acquire position information of the buckle-binding line on the equidistant curve, wherein the position information includes the starting and ending positions of the buckle-binding line on the equidistant curve;

[0075] An equidistant curve drawn based on the first equidistant radius has multiple buckle lines on it, and the starting and ending positions of the buckle lines on the equidistant curve are obtained as position information of the buckle lines.

[0076] There is a corresponding relationship between the contour line of the stator cavity and the equidistant curve of the stator, and the position information of the buckle line determined on the equidistant curve also corresponds to the position information of the position where interference may exist on the contour line of the stator cavity.

[0077] S104: Determine a position to be optimized on the stator cavity based on the position information, and optimize a contour line of the position to be optimized.

[0078] Based on the above correspondence, the specific position on the stator cavity contour line where interference occurs with the rotor can be determined. This is the position to be optimized. When the rotor performs planetary motion in the stator cavity, interference occurs to the position to be optimized, and the contour line of the position to be optimized needs to be corrected.

[0079] Specifically, since the position on the stator cavity of the screw motor corresponding to the buckle line will cause interference during the rotation of the rotor, it is necessary to slightly increase the distance between it and the rotor when it runs to this position, and set a corresponding arc transition section at the position to be optimized, that is, increase the equidistant radius between any point on it and the stator bone line of the screw motor, that is, the position to be optimized has a second equidistant radius relative to the contour line of the stator cavity, and the second equidistant radius is larger than the first equidistant radius, thereby avoiding interference with the position to be optimized during the movement of the rotor.

[0080] The method for optimizing the stator cavity contour line of a screw motor provided in an embodiment of the present invention optimizes the stator cavity contour by identifying the buckle lines appearing on the stator equidistant curve and setting an arc-shaped transition section with a larger equidistant radius according to the position of the buckle lines, thereby reducing the interference between the stator and the rotor.

[0081] Figure 8 A schematic diagram of the structure of a universal joint shaft provided in an embodiment of the present invention is shown in FIG. Figure 8 As shown, on the basis of the above embodiments, the lower end of the rotor is further connected to the universal shaft 3, including a rotor joint (3-1), a movable seat (3-2), a movable shaft (3-3), a limit pin (3-4) and a connecting rod (3-5). The drilling fluid is discharged through the screw motor 2 and enters the channel between the universal shaft 3 and the housing. With the continuous output of the motor's hydraulic energy, the drilling fluid flows into the transmission shaft 4.

[0082] Fig. 9 A schematic diagram of the transmission shaft structure provided by an embodiment of the present invention, such as Fig. 9As shown, on the basis of the above embodiments, further, the lower end of the universal shaft 3 is connected to the transmission shaft 4, including a water cap (4-1), a transmission shaft (4-2), an upper TC bearing static ring (4-3), an upper TC bearing dynamic ring (4-4), an upper spacer assembly (4-5), a transmission shaft housing (4-6), a PDC thrust bearing (4-7), a shaft washer (4-8), a locking mechanism (4-9), a lower TC bearing static ring (4-10), a lower TC bearing dynamic ring (4-11), and a semicircular key (4-12).

[0083] The upper spacer assembly (4-5) includes a ring sleeve (4-13) and an inner sleeve (4-14). Fig.10 A schematic diagram of a ring structure provided in an embodiment of the present invention, Fig.11 A schematic diagram of the structure of an inner sleeve provided in an embodiment of the present invention, Fig.12 The schematic diagram of the structure of the upper spacer assembly provided in the embodiment of the present invention, the structure of the upper spacer assembly (4-5) and the ring sleeve (4-13) and the inner sleeve (4-14) is as follows Fig.10 , Fig.11 and Fig.12 shown.

[0084] Fig.13 A schematic diagram of the structure of a PDC thrust bearing provided in an embodiment of the present invention is shown in FIG. Fig.13 As shown, on the basis of the above-mentioned embodiments, further, the PDC thrust bearing (4-7) includes a bearing outer ring (4-15), a bearing inner ring (4-16), an outer spacer (4-17) and an inner spacer (4-18).

[0085] Fig.14 A schematic diagram of the structure of a bearing outer ring provided in an embodiment of the present invention, Fig.15 The structure diagram of the bearing inner ring provided in the embodiment of the present invention is as follows: Fig.14 and Fig.15 As shown, the outer ring (4-15) of the bearing is added with a polycrystalline diamond composite sheet, such as Fig.14 The raised part in the middle makes the entire bearing group more wear-resistant and prolongs the service life of the transmission shaft assembly. In addition, the drilling fluid enters the transmission shaft to play a lubricating role.

[0086] In the description of this specification, the description with reference to the terms "one embodiment", "a specific embodiment", "some embodiments", "for example", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0087] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A screw motor, characterized in that: include: stator and rotor; in The stator comprises a stator housing and a stator cavity, wherein a spiral cavity is arranged in the stator cavity, wherein the contour line of the stator cavity is a petal-shaped line formed by connecting a plurality of groups of first convex circular arc segments and second concave circular arc segments end to end in sequence, and an arc-shaped transition section is arranged between the first circular arc segment and the second circular arc segment; The stator is sleeved on the rotor, and the outer surface of the stator matches the inner surface of the spiral cavity.

2. The screw motor according to claim 1, characterized in that: The stator cavity is made of rubber.

3. The screw motor according to claim 2, characterized in that: The stator and the rotor are in interference fit.

4. The screw motor according to claim 1, characterized in that: The stator cavity is made of metal and is integrally formed with the stator housing.

5. The screw motor according to claim 4, characterized in that: The stator and the rotor are clearance-fitted.

6. The screw motor according to any one of claims 1 to 5, characterized in that: The first arc segment and the second arc segment have a first equidistant radius relative to the contour line of the stator cavity, and the arc-shaped transition segment has a second equidistant radius relative to the contour line of the stator, and the second equidistant radius is greater than the first equidistant radius.

7. The screw motor according to claim 6, characterized in that: The position of the arc-shaped transition section corresponds to the position of the buckle line on the contour line of the stator cavity.

8. The screw motor according to claim 7, characterized in that: The starting and ending positions of the arc-shaped transition section correspond to the starting and ending positions of the buckle line.

9. A screw drill, characterized in that: include: An anti-drop assembly, a screw motor as described in any one of claims 1 to 8, a universal joint shaft and a transmission shaft connected in sequence.

10. A method for optimizing the stator cavity contour of a screw motor, characterized in that: include: Obtain the cycloid shape of the stator cavity; Based on the cycloid line shape and a preset first equidistant radius, drawing an equidistant curve of the cycloid line shape; Acquire position information of a buckle line on the equidistant curve, wherein the position information includes a start and end position of the buckle line on the equidistant curve; The position to be optimized on the stator cavity is determined based on the position information, and the contour line of the position to be optimized is optimized.

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