A universal joint

Abstract

This invention proposes a universal joint, belonging to the technical field of connection devices, comprising a water cap assembly and a mandrel installed inside the water cap assembly; the water cap assembly includes a hinged water cap, one end of which is provided with a sealing cavity, the bottom of which is provided with a hemispherical groove, and the sidewall of the sealing cavity is provided with several strip grooves, which communicate with the hemispherical groove; a sealing spherical surface is installed in the hemispherical groove; the side of the mandrel is provided with several torsion transmission planes arranged in a circumferential array, which are connected to the sealing spherical surface; the surface of the torsion transmission plane is provided with a mounting hole, in which a mushroom-shaped pin is rotatably installed, and the outer surface of the mushroom-shaped pin is in contact with the surface of a sliding bushing slidably installed in the strip groove. The contact between the outer surface of the mushroom-shaped pin and the surface of the sliding bushing, and the engagement between the hemispherical groove and the sealing spherical surface, achieves surface contact, increases the force-bearing area, reduces wear, and extends the service life of the device.

Description

Technical Field

[0001] This invention belongs to the field of connection device technology, and specifically relates to a universal joint. Background Technology

[0002] Some mechanical operations often require universal joints to transmit torque to drive the drill bit. For example, screw drills require universal joints to transmit the torque of the screw motor rotor to the drive shaft to drive the drill bit. Currently, there are two common types of universal joints: double universal joints and integrated flexible universal joints. These two types of universal joints are widely used but have some problems, such as: universal joint seal failure leading to wear and failure; and integrated universal joints having a limited service life and being prone to fatigue fracture.

[0003] CN108006093A discloses a universal joint cross shaft, comprising: a cross-shaped universal joint base, with end caps at all four ends of the universal joint base; the universal joint base also has longitudinal oil passages and transverse oil passages inside, the longitudinal oil passages penetrating the center of the universal joint base and a pair of longitudinal end caps; the transverse oil passages penetrating the center of the universal joint base and a pair of transverse end caps; and radial oil holes are provided on the end caps, connecting to the longitudinal or transverse oil passages. This invention reduces flow path, resistance, and oil consumption, while increasing lubrication, reducing dry friction that could cause the drive shaft to jam during operation, thus preventing vehicle accidents, and extending the service life of the universal joint cross shaft assembly.

[0004] The aforementioned universal joints and universal shafts use steel balls to transmit torque. These torque transmission methods cannot achieve surface contact between the force-bearing components during the entire movement process, and are mostly line contact and point contact. Even if the universal shaft is always in a lubricated environment, wear and vibration impact will occur. The vibration impact generated by these non-comprehensive contacts will also lead to seal failure and accelerate the damage of the universal joint.

[0005] Based on the above problem analysis and combined with the field requirements, this invention patent designs a surface contact sealing universal joint, which aims to improve the service life of conventional universal joints and reduce drilling accidents. Summary of the Invention

[0006] To address the above problems, this invention proposes a universal joint, comprising a water cap assembly and a spindle installed inside the water cap assembly;

[0007] The water cap assembly includes a hinged water cap, one end of which is provided with a sealing cavity, the bottom of which is provided with a hemispherical groove, and the sidewall of which is provided with a plurality of strip grooves, and the strip grooves are connected to the hemispherical grooves.

[0008] One end of the mandrel is provided with a sealing spherical surface, which is installed in a hemispherical groove; the side of the mandrel is provided with a plurality of torsion transmission planes arranged in a circumferential array, which are connected to the sealing spherical surface; the surface of the torsion transmission plane is provided with a mounting hole, in which a mushroom nail is rotatably installed, and the outer surface of the mushroom nail is in contact with the surface of the sliding liner block slidably installed in the strip groove.

[0009] Furthermore, the center of the spherical surface of the mushroom-shaped nail coincides with the center of the sealing spherical surface.

[0010] Furthermore, the hinged water cap is provided with an oil storage cavity, which is connected to the hemispherical groove through a connecting hole, and the oil storage cavity, the hemispherical groove and the strip groove are filled with lubricating oil.

[0011] Furthermore, a compensation piston is installed at the end of the oil storage chamber away from the connecting hole.

[0012] Furthermore, a groove is provided on the surface of the sealing ball, and the groove communicates with the strip groove and the connecting hole.

[0013] Furthermore, the universal joint also includes a sealing bearing and a sealing sleeve that interlock with each other. The outer surface of the sealing bearing is sealed and installed on the inner surface of the sealing cavity, and the arc surface of the sealing bearing is sealed and installed on the pressing ball surface of the mandrel. The pressing ball surface is located on the outer surface of the mandrel and is located on the side of the mounting hole away from the sealing ball surface.

[0014] The sealing sleeve is located between the mandrel and the hinged water cap, with the end of the sealing sleeve away from the sealing bearing sealed to the outer surface of the mandrel.

[0015] Furthermore, a conical retaining ring is provided in the groove near the surface of the pressing ball of the sealing bearing, and the conical retaining ring is in contact with the pressing ball.

[0016] Furthermore, an O-ring is provided in the groove of the inner wall of the sealing cavity, and the O-ring fits into the sealing bearing.

[0017] Furthermore, the universal joint also includes a clamping sleeve and a clamping disc spring in contact with each other. The clamping sleeve is threadedly installed in the sealing cavity, and the end of the clamping disc spring away from the clamping sleeve is in contact with the sealing rubber sleeve.

[0018] Furthermore, the universal joint also includes a second retaining ring and a support sleeve, the second retaining ring being located between the clamping sleeve and the clamping disc spring, and the support sleeve being located between the second retaining ring and the hinged water cap.

[0019] Furthermore, the universal joint also includes a limiting sleeve, which is sealed to the spindle, and the limiting sleeve contacts the end of the sealing rubber sleeve away from the sealing bearing, and the limiting sleeve contacts the clamping sleeve.

[0020] Beneficial effects of this invention:

[0021] 1. The outer surface of the mushroom-shaped nail of the present invention is in contact with the surface of the sliding liner, and the hemispherical groove is in sync with the sealing sphere, thereby achieving surface contact, increasing the force-bearing area, reducing wear, and improving the service life of the device.

[0022] 2. In this invention, the center of the spherical surface of the outer surface of the mushroom-shaped nail coincides with the center of the sealing spherical surface, ensuring that the sealing spherical surface and the hemispherical groove of the universal joint spindle can slide along the spherical surface, reducing friction.

[0023] 3. The sealing sphere of the present invention is provided with a groove, which is connected to the strip groove and the groove is connected to the connecting hole, so that the lubricating oil in the sealing cavity of the hinged water cap can be fully immersed into the sealing cavity and provide lubrication effect for the spherical contact surface.

[0024] 4. The universal joint of the present invention also includes a clamping sleeve and a clamping disc spring. The clamping sleeve is installed on the outside of the spindle, and the other part is installed on the inside of the sealing cavity and contacts the clamping disc spring. The end of the clamping disc spring away from the clamping sleeve contacts the sealing rubber sleeve. The clamping disc spring is used to provide preload force, thereby keeping the sealing bearing in contact with the clamping ball surface and improving the sealing effect.

[0025] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A schematic diagram of the universal joint structure in an embodiment of the present invention is shown.

[0028] Figure 2 A schematic cross-sectional view of the mandrel and water cap assembly of the universal joint in an embodiment of the present invention is shown.

[0029] Figure 3 It shows Figure 2 A magnified view of a portion of the image.

[0030] Figure 4 A cross-sectional schematic diagram of the assembly of the mandrel and water cap of the universal joint in an embodiment of the present invention is shown.

[0031] Figure 5 A schematic diagram of the mandrel structure of the universal joint in an embodiment of the present invention is shown.

[0032] Figure 6 It shows Figure 5 A partial schematic diagram.

[0033] Figure 7 A schematic diagram of the mandrel cross-section of the universal joint in an embodiment of the present invention is shown.

[0034] Figure 8 A schematic diagram of the principle of the universal joint in an embodiment of the present invention is shown.

[0035] Figure 9 A schematic diagram illustrating the working principle of the mushroom-shaped pin in the universal joint according to an embodiment of the present invention is shown.

[0036] In the diagram, 1 is the spindle; 101 is the mounting hole; 102 is the groove; 103 is the torque transmission plane; 104 is the sealing spherical surface; and 105 is the clamping spherical surface.

[0037] 2. Water cap assembly; 201. Limiting sleeve; 202. Compression sleeve; 203. Sealing bearing; 204. Hinged water cap; 205. Sealing rubber sleeve; 206. Compression disc spring; 207. Sliding liner; 208. Mushroom pin; 209. First retaining ring; 210. Compensating piston; 211. Connecting hole; 212. Conical retaining ring; 213. Support sleeve; 214. Second retaining ring; 215. O-ring seal; 216. Oil filling hole; 217. Oil reservoir; 218. Sealing cavity; 2181. Hemispherical groove; 2182. Strip groove. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] like Figure 1 As shown, Figure 1 A schematic diagram of the universal joint structure in an embodiment of the present invention is shown. (Reference) Figure 1A universal joint includes a water cap assembly 2 and a spindle 1 installed inside the water cap assembly 2. The water cap assembly 2 includes a hinged water cap 204, one end of which is provided with a sealing cavity 218. The bottom of the sealing cavity 218 is provided with a hemispherical groove 2181, and the sidewall of the sealing cavity 218 is provided with a plurality of strip grooves 2182, which communicate with the hemispherical grooves 2181. The communicating strip grooves 2182 and hemispherical grooves 2181 allow lubricating oil to pass through and lubricate all contact points. Specifically, the hinged water cap 204 is mutually restrained by a sliding bushing 207 and a mushroom pin 208, and the remaining gaps are filled with a large amount of grease. Since all internal components are in surface contact, this sealed universal joint has high rigidity and service life during torque transmission. If the internal sliding liner 207 or mushroom nail 208 is severely worn, it can be replaced and re-lubricated individually, without scrapping the entire sealing universal joint, thus saving costs for the company.

[0040] In this invention, a sealing spherical surface 104 is provided at one end of the mandrel 1, and the sealing spherical surface 104 is installed in a hemispherical groove 2181; a plurality of torsion transmission planes 103 arranged in a circumferential array are provided on the side of the mandrel 1, and the torsion transmission planes 103 are connected to the sealing spherical surface 104. The mandrel 1 has a slender rod structure, one end of which is connected to the torque output end, and the other end is a universal joint structure. The end of the mandrel 1 has a torsion transmission plane 103 and a sealing spherical surface 104. A mounting hole 101 is provided on the surface of the torsion transmission plane 103, and a mushroom-shaped pin 208 is rotatably installed in the mounting hole 101, and the outer surface of the mushroom-shaped pin 208 is in contact with the surface of the sliding bushing 207 slidably installed in the strip groove 2182. Specifically, refer to Figure 5 , Figure 6 and Figure 7 In this embodiment, the right end of the mandrel 1 has a hexagonal structure (i.e., a regular hexagonal prism, meaning there are six torsion transmission planes 103, which can also be set to eight as needed). Mounting holes 101 are drilled at the centers of the six torsion transmission planes 103 for assembling mushroom-shaped pins 208. The right end face of the mandrel 1 has a spherical structure, with grooves 102 milled into it. This facilitates the lubricating oil in the sealing cavity 218 of the hinged water cap 204 to fully penetrate the sealing cavity 218, providing lubrication for the spherical contact surfaces (i.e., the contact surface between the mushroom-shaped pin 208 and the sliding bushing 207, the contact surface between the sealing bearing 203 and the pressing spherical surface 105, and the contact surface between the sealing spherical surface 104 and the hemispherical groove 2181).

[0041] Furthermore, a groove 102 is provided on the sealing spherical surface 104, which communicates with the strip groove 2182 and the connecting hole 211. The groove 102 facilitates the entry of lubricating oil into the strip groove 2182 and then into the contact surface between the mushroom pin 208 and the sliding liner 207, thus achieving a continuous supply of lubricating oil.

[0042] Specifically, refer to Figure 5 The left end of mandrel 1 has a special straight thread that connects to the rotor of the screw motor. The right end of the thread has a certain taper, which provides a certain degree of erosion resistance. Mandrel 1 also has a marking groove for stamping to facilitate subsequent traceability. The middle part of mandrel 1 has a variable diameter structure. Finite element analysis shows that the variable diameter in the middle, with a large fillet transition, can effectively alleviate stress concentration and prevent fatigue fracture of mandrel 1 during long-term operation, thus avoiding downhole accidents.

[0043] Please refer to Figure 2 , Figure 2 This diagram shows a cross-sectional view of the universal joint's spindle and water cap assembly in an embodiment of the invention. The center of the spherical surface of the mushroom-shaped pin 208 coincides with the center of the sealing spherical surface 104. This ensures that the spheres are aligned during rotation, resulting in consistent rotational stroke and reduced jamming.

[0044] Specifically, the hinged water cap 204 is provided with an oil storage cavity 217, which is connected to the hemispherical groove 2181 through a connecting hole 211. The oil storage cavity 217, the hemispherical groove 2181, and the strip groove 2182 are filled with lubricating oil. This is to ensure that the lubricating oil in the sealing cavity 218 of the hinged water cap 204 fully penetrates the interior of the sealing cavity 218, providing lubrication for the spherical contact surfaces (i.e., the contact surface between the mushroom pin 208 and the sliding bushing 207, the contact surface between the sealing bearing 203 and the pressing spherical surface 105, and the contact surface between the sealing spherical surface 104 and the hemispherical groove 2181). The hinged water cap 204 is provided with an oil injection hole 216, which is connected to the sealing cavity 218 and is misaligned with the strip groove 2182.

[0045] Furthermore, a compensating piston 210 is installed at the end of the oil reservoir 217 away from the connecting hole 211. The universal joint also includes a sealing bearing 203 and a sealing sleeve 205. The outer surface of the sealing bearing 203 is sealed and installed on the inner surface of the sealing cavity 218, and the arc surface of the sealing bearing 203 is sealed and installed on the pressing ball surface 105 of the spindle 1. The pressing ball surface 105 is located on the outer surface of the spindle 1 and on the side of the mounting hole 101 away from the sealing ball surface 104. The sealing sleeve 205 is located between the spindle 1 and the hinged water cap 204, and the sealing sleeve 205 is located at the end of the sealing bearing 203 away from the pressing ball surface 105. The sealing sleeve 205 is engaged with the sealing bearing 203, and the end of the sealing sleeve 205 away from the sealing bearing 203 is sealed and connected to the outer surface of the spindle 1. To protect the universal joint from wear and ensure effective torque transmission, a lubrication and sealing structure is incorporated. The sealing sleeve 205 is tightly fitted to the spindle 1 to prevent external mud pressure from compressing and tearing the sealing sleeve 205. Since the sealing sleeve 205 is in long-term contact with drilling fluid, it requires corrosion and oil resistance.

[0046] Specifically, a tapered retaining ring 212 is provided in the groove near the surface of the pressing spherical surface 105 of the sealing bearing 203, and the tapered retaining ring 212 fits against the pressing spherical surface 105. This achieves a seal on the strip-shaped groove 2182, preventing lubricating oil from escaping. An O-ring 215 is provided in the groove on the inner wall of the sealing cavity 218, and the O-ring 215 fits against the sealing bearing 203, improving the sealing performance.

[0047] refer to Figure 2 and Figure 3 The universal joint also includes a clamping sleeve 202 and a clamping disc spring 206 that are in contact with each other. The clamping disc spring 206 is threadedly installed in the sealing cavity 218, and the end of the clamping disc spring 206 away from the clamping sleeve 202 is in contact with the sealing rubber sleeve 205. The end of the clamping sleeve 202 away from the clamping disc spring 206 extends out of the sealing cavity 218 and is connected to the hinged water cap 204. The clamping disc spring 206 is used to provide preload force, thereby keeping the sealing bearing 203 in contact with the clamping spherical surface 105.

[0048] Furthermore, the articulated water cap 204 is provided with an oil filling hole 216, which is sealed with an oil plug. After the overall structure is assembled, lubricating grease needs to be filled into the entire articulated sealing cavity 218 through the oil filling hole 216 of the articulated water cap 204. The articulated water cap 204 is provided with an oil reservoir 217, which is equipped with a compensating piston 210. The oil reservoir 217 is equipped with a compensating piston 210 to balance the internal and external pressure difference of the sealing cavity 218 (to balance the internal and external pressure of the sealing sleeve 205 and prevent the sealing sleeve 205 from tearing due to pressure difference) and to replenish the lubricating grease in the sealing cavity 218, ensuring that the structure always has lubricating grease during operation. A threaded connection is used between the hinged water cap 204 and the clamping sleeve 202. The clamping sleeve 202 clamps the sealing sleeve 205 and the sealing bearing 203 by clamping the disc spring 206. The spherical surface of the sealing bearing 203 cooperates with the clamping spherical surface 105 of the mandrel 1 to achieve spherical limit. At the same time, the sealing bearing 203 is provided with a sealing structure. The outer circle seal of the sealing bearing 203 and the sealing cavity 218 achieve sealing. The spherical sealing structure of the sealing bearing 203 is clamped with the clamping spherical surface 105 of the mandrel 1 to achieve sealing.

[0049] The universal joint also includes a second retaining ring 214 and a support sleeve 213. The second retaining ring 214 is located between the clamping sleeve 202 and the clamping disc spring 206, and the support sleeve 213 is located between the second retaining ring 214 and the hinge cap 204. By placing the second retaining ring 214 between the clamping disc spring 206 and the sealing sleeve 205, the force is evenly distributed to the sealing sleeve 205, preventing the sealing sleeve 205 from being damaged due to concentrated force. The support sleeve 213 is used to limit and position the clamping disc spring 206.

[0050] Specifically, the universal joint also includes a limiting sleeve 201, which is sealed to the spindle 1. The limiting sleeve 201 contacts the end of the sealing sleeve 205 away from the sealing bearing 203, and the limiting sleeve 201 contacts the clamping sleeve 202. The function of the limiting sleeve 201 is to alleviate the direct erosion of the gap between the end face of the clamping sleeve 202 and the sealing sleeve 205 by high-pressure drilling fluid, prevent the formation of eddy currents that erode the parts, and improve service life.

[0051] The positioning of the spindle 1 and the water cap assembly 2 is achieved by the sealing spherical surface 104 at the bottom of the spindle 1 and the pressing spherical surface 105 on the back. The sealing spherical surface 104 and the pressing spherical surface 105 on the back are two spherical structures with the same center but different radii. The sealing spherical surface 104 is used in conjunction with the hinged water cap 204. Its purpose is to ensure that the sealing spherical surface 104 and the hemispherical groove 2181 of the spindle 1 in the universal joint can slide along the spherical surface to reduce friction. The universal joint's torsion transmission structure is achieved through a sliding bushing 207 and a mushroom-shaped pin 208 with an arc surface. The bottom of the sliding bushing 207 engages with the strip groove 2182. The concave arc surface of the sliding bushing 207 engages with the convex arc surface of the mushroom-shaped pin 208 to achieve surface contact for arc surface rotation. The arc surfaces of the mushroom-shaped pin 208 are planar structures and can move along the plane of the spindle 1. To ensure that the rotation axis of the mushroom-shaped pin 208 passes through the center of the spindle 1, a cylindrical structure is provided in the middle of the plane of the mushroom-shaped pin 208. The cylinder of the mushroom-shaped pin 208 engages with the mounting hole 101 on the torsion transmission plane 103 to achieve rotational freedom around the cylinder in any direction. The axis of the cylindrical hole in the torsion transmission plane 103 all passes through the center of the ball. Before assembly, the mushroom-shaped nail 208 and the hinged water cap 204 need to be assembled first, and then the mushroom-shaped nail 208 needs to be mated with the hinged water cap 204. Because its structure is six-sided (setting the torsion transmission plane 103 to six sides is more reasonable, but it can also be set to two, three, four, five, seven, or eight sides; the maximum is eight due to space constraints), the mushroom-shaped nail 208 and the sliding bushing 207 have surface contact, which improves the torsion transmission force between the sliding bushing 207 and the hinged water cap 204. The clamping spherical surface 105 of the mandrel 1 is a large-radius spherical structure that fits with the spherical surface of the sealing bearing 203. The sealing sleeve 205 is connected to the sealing bearing 203. The end face is fitted with a clamping disc spring 206. The clamping disc spring 206, the sealing sleeve 205 and the sealing bearing 203 are fitted onto the surface of the clamping spherical surface 105 using a clamping sleeve 202. The clamping sleeve 202 is threadedly connected to the threaded port of the hinged water cap 204. In order to prevent external media from entering the sealing sleeve 205, a limiting sleeve 201 is fitted at its other end. When the drilling fluid flushes, the limiting sleeve 201 can effectively block the drilling fluid from eroding the mandrel 1 through its conical surface.

[0052] refer to Figure 8 and Figure 9Taking the center of the sealing spherical surface 104 at the right end of the mandrel 1 as the reference point, the mandrel 1 is the y-axis, the central axis of any mushroom nail 208 is the x-axis, and the axis perpendicular to it is the z-axis. As shown in the figure, the mandrel 1 can rotate arbitrarily up, down, left, and right within the plane formed by the x-axis and z-axis (that is, by slightly rotating along the axis of the central axis of any mushroom nail 208, with a rotation angle of less than 2 degrees). When the mandrel 1 rotates, the mushroom nail 208 will be restrained by the mandrel 1 and rotate around the x-axis. When the mushroom nail 208 rotates, the mandrel 1 and the water cap assembly 2 achieve a bending effect. The linkage between the mandrel 1, the sliding bushing 207, and the mushroom nail 208 realizes the motion mechanism of the overall universal joint rotating in all directions, thereby enabling the present invention to achieve the effect of bending at any angle between the mandrel 1 and the water cap assembly 2.

[0053] Assembly process:

[0054] During assembly, refer to Figure 2 and Figure 3 The hinged water cap 204 is connected to the assembly via the sealing cavity 218. The sliding bushing 207 and mushroom pin 208 are bonded together using the adhesive of lubricating oil. The sealing bearing 203 is assembled with the O-ring 215 and the second retaining ring 214, which are then inserted into the spindle 1. The sealing sleeve 205 is inserted from the left end of the spindle 1. During assembly, care should be taken not to damage the sealing sleeve 205. The sealing sleeve 205 and the sealing bearing 203 have assembly grooves, which are used for connection. Before assembly, the sealing bearing 203 needs to be cleaned with a cleaning agent and wiped clean to remove any oil stains. Rubber adhesive is evenly applied to the sealing cavity 218. After assembling the sealing sleeve 205 and the sealing bearing 203, the assembly part is locked with a hose clamp. After the adhesive is completely bonded, the hose clamp is removed and cleaned.

[0055] Fill the bonded sealing sleeve 205 with grease and assemble it into the area shown in Figure 2 of the water cap assembly. The main purpose of the grease is to ensure that the sealing sleeve 205 is not damaged by the high-pressure drilling fluid downhole. Install the clamping disc spring 206 onto the sealing sleeve 205, and connect the clamping sleeve 202 to the threaded connection of the hinged water cap 204. Tighten the torque and spot weld with electric welding to prevent downhole disengagement. Since there is a certain gap between the end face of the clamping sleeve 202 and the sealing sleeve 205, the function of the limiting sleeve 201 is to alleviate the direct erosion of the gap between the end face of the clamping sleeve 202 and the sealing sleeve 205 by the high-pressure drilling fluid, avoid the formation of eddy currents that erode the parts, and improve service life.

[0056] After assembly, use a high-pressure grease injector to fill the sealing cavity 218 with a large amount of grease. Stop grease injection after a large amount of grease overflows from the assembly hole of the hinged water cap 204. Press the O-ring 215 of the compensating piston 210 into the sealing cavity 218, ensuring that the end face of the compensating piston 210 is flush with the end face of the hole of the second retaining ring 214. Install the first retaining ring 209 and insert the retaining ring for limiting. After grease injection, seal the compensating piston 210 with a threaded plug.

[0057] Working principle:

[0058] In use, the screw motor rotor is threadedly connected to the end of the mandrel 1 away from the water cap assembly 2. The end of the water cap assembly 2 away from the mandrel 1 is threadedly connected to the drive shaft. When the high-pressure drilling fluid passes through the screw motor, the screw motor drives the non-mandrel 1 to start rotating. Since the downhole drill has a certain bending angle and the rotor performs planetary motion in the screw stator housing, the sealed universal joint rotates synchronously with the screw motor rotor after bending at a certain angle (a small bending angle, with an angle range of 0-2 degrees), transmitting torque and transferring the kinetic energy generated by the screw motor to the drill bit clamped at the drive shaft head for rock breaking and drilling.

[0059] During operation, the screw drill itself has a certain bend angle, and its main purpose is to transmit the kinetic energy generated by the screw motor to the drill bit. When passing through the bend angle, the hinge structure will bend according to the direction of the bend angle. The purpose of designing it as a universal joint is to improve the service life of the universal joint under such high torque and high-speed rotational torque transmission. After assembly, the mushroom nail 208 can rotate around the cylinder of the mandrel 1, ensuring that the arc surface of the mushroom nail 208 still maintains surface contact at any angle. The sealing cavity 218 is a strip groove 2182 corresponding to the assembled mandrel 1. After the overall assembly is completed, it is different from the previous hinged universal joint. Because its interior is in surface contact and the mushroom pins 208 and sliding bushings 207 in each direction are mutually restrained, when it bends to one side, the mushroom pins 208 in the bending direction and the sliding bushings 207 directly emit a slight rotation. The other mushroom pins 208 and the sliding bushings 207 are mutually restrained due to different bending angles. The sliding bushings 207 and the strip groove 2182 will have a slight displacement. Due to the structural constraints such as the pressure disc spring 206 and the pressure sleeve 202, this slight displacement will quickly return to its original position according to the rotation of the universal joint. It is through the operating mechanism of this structure that the internal stress generated in this part is released and stress concentration is eliminated. Therefore, the present invention is more robust and has better rigidity. After conventional universal joints are assembled, there will be a certain gap in order to meet the bending requirements, but the present invention will not have this phenomenon. The advantage of surface contact is that it has greater toughness and service life. Moreover, if the internal mushroom nail 208 and sliding bushing 207 are severely worn, the spindle 1 can be disassembled and the internal parts replaced as needed, without scrapping the entire spindle 1.

[0060] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A universal joint, characterized in that, It includes a water cap assembly (2) and a spindle (1) installed inside the water cap assembly (2); The water cap assembly (2) includes a hinged water cap (204), one end of which is provided with a sealing cavity (218), the bottom of which is provided with a hemispherical groove (2181), and the sidewall of which is provided with a plurality of strip grooves (2182), and the strip grooves (2182) are connected to the hemispherical grooves (2181); One end of the mandrel (1) is provided with a sealing spherical surface (104), which is installed in a hemispherical groove (2181); the side of the mandrel (1) is provided with a plurality of torsion transmission planes (103) arranged in a circular array, which are connected to the sealing spherical surface (104); the surface of the torsion transmission plane (103) is provided with a mounting hole (101), in which a mushroom nail (208) is rotatably installed, and the outer surface of the mushroom nail (208) is in contact with the surface of the sliding liner (207) which is slidably installed in the strip groove (2182).

2. A universal joint according to claim 1, characterized in that, The center of the sphere of the mushroom nail (208) coincides with the center of the sphere of the sealing sphere (104).

3. A universal joint according to claim 1, characterized in that, The articulated water cap (204) is provided with an oil storage cavity (217), which is connected to the hemispherical groove (2181) through a connecting hole (211). The oil storage cavity (217), the hemispherical groove (2181) and the strip groove (2182) are filled with lubricating oil.

4. A universal joint according to claim 3, characterized in that, A compensating piston (210) is installed at the end of the oil storage chamber (217) away from the connecting hole (211).

5. A universal joint according to claim 1, characterized in that, The sealing spherical surface (104) is provided with a groove (102), which is connected to the strip groove (2182) and the connecting hole (211).

6. A universal joint according to claim 1, characterized in that, The universal joint also includes a sealing bearing (203) and a sealing sleeve (205) that interlock with each other. The outer surface of the sealing bearing (203) is sealed and installed on the inner surface of the sealing cavity (218), and the arc surface of the sealing bearing (203) is sealed and installed on the pressing ball surface (105) of the mandrel (1). The pressing ball surface (105) is located on the outer surface of the mandrel (1) and on the side of the mounting hole (101) away from the sealing ball surface (104). The sealing sleeve (205) is located between the mandrel (1) and the hinged water cap (204), and the end of the sealing sleeve (205) away from the sealing bearing (203) is sealed and connected to the outer surface of the mandrel (1).

7. A universal joint according to claim 6, characterized in that, The sealing bearing (203) has a conical retaining ring (212) in the groove near the surface of the pressing spherical surface (105), and the conical retaining ring (212) fits against the pressing spherical surface (105).

8. A universal joint according to claim 6, characterized in that, An O-ring (215) is provided in the groove of the inner wall of the sealing cavity (218), and the O-ring (215) fits against the sealing bearing (203).

9. A universal joint according to any one of claims 6-8, characterized in that, The universal joint also includes a clamping sleeve (202) and a clamping disc spring (206) in contact with each other. The clamping sleeve (202) is threadedly installed in the sealing cavity (218), and the end of the clamping disc spring (206) away from the clamping sleeve (202) is in contact with the sealing rubber sleeve (205).

10. A universal joint according to claim 9, characterized in that, The universal joint also includes a second retaining ring (214) and a support sleeve (213). The second retaining ring (214) is located between the clamping sleeve (202) and the clamping disc spring (206), and the support sleeve (213) is located between the second retaining ring (214) and the hinged water cap (204).

11. A universal joint according to claim 9, characterized in that, The universal joint also includes a limiting sleeve (201), which is sealed to the spindle (1), and the limiting sleeve (201) contacts the end of the sealing rubber sleeve (205) away from the sealing bearing (203), and the limiting sleeve (201) contacts the clamping sleeve (202).

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