A full-time contact shock-absorbing universal shaft assembly

Abstract

The present application relates to a full-time contact damping type universal shaft assembly, belonging to the technical field of screw drill tools for oil and natural gas drilling, comprising: a universal shaft, which includes an intermediate shaft and a universal joint sleeved on the end of the intermediate shaft, the end of the intermediate shaft has a plurality of spaced external teeth along the circumferential direction, and the inner universal joint has a plurality of spaced internal teeth along the circumferential direction, the external teeth and the internal teeth are meshed with each other, thereby performing a variable angle transmission connection; an elastic member, the tooth surface of the external teeth contacting the internal teeth is the external teeth stress surface, and the tooth surface of the internal teeth contacting the external teeth is the internal teeth stress surface, and the elastic member is arranged between the external teeth stress surface and the internal teeth stress surface, so that the adjacent external teeth and internal teeth are in full-time contact. The elastic member of the present application enables the external teeth at both ends of the intermediate shaft and the internal teeth of the universal joint to contact at the same time, dispersing the torque generated by the motor to the external teeth of each intermediate shaft and the internal teeth of the universal joint, reducing the contact stress of each external tooth and internal tooth, thereby improving the service life of the universal shaft assembly.

Description

Technical Field

[0001] The present application relates to the technical field of screw drill tools for oil and natural gas drilling, and in particular to a full-time contact shock-absorbing universal shaft assembly. Background Art

[0002] In the exploitation of oil and gas, screw drilling tools are increasingly used. The screw drilling tools include a bypass valve assembly, a motor assembly, a universal shaft assembly and a transmission shaft assembly. Each component is connected in sequence from top to bottom. The upper end of the universal shaft is connected to the motor rotor, and the lower end is connected to the transmission shaft. Its function is to convert the planetary motion of the motor rotor into the fixed axis motion of the transmission shaft, so that the torque and speed generated by the motor are smoothly transmitted to the drill bit.

[0003] As oil and gas production is committed to continuously reducing operating costs, increasing the working torque output by screw drill bits to the drill bit has become a commonly used method to effectively increase mechanical drilling speed and reduce costs. As the torque of the screw drill increases, the torque borne by the universal joint increases. Therefore, it is necessary to improve the load-bearing capacity of the universal joint and extend the service life of the universal joint.

[0004] In the related art, there are sealed and unsealed universal joint assemblies, but they all include an upper joint, a ball seat, a support ball, an intermediate shaft, a lower joint, etc., and have the main function of transmitting motor torque and motion. The upper joint is connected to the lower end of the rotor, and the lower joint is connected to one end of the transmission shaft or the water cap. The upper joint and the lower joint are parts with an internal tooth structure. The upper joint and the lower joint are connected by an intermediate shaft with external teeth at both ends, which can be rotated and connected respectively, so that the torque generated by the motor can be transmitted to the drill bit.

[0005] However, after the motor rotor is installed in the stator, there is an eccentricity between the center line of the rotor and the center line of the stator, and due to the bending angle of the screw drill structure, there is an angle between the axis of the intermediate shaft with external teeth at both ends and the axes of the upper joint and the lower joint, so that the external teeth at both ends of the intermediate shaft and the internal teeth of the upper joint and the lower joint, which were initially designed as coaxial, cannot contact at the same time. In addition, during the rotation of the motor rotor, there is a periodic gap change between the external teeth of the intermediate shaft and the internal teeth of the upper joint and the lower joint, which leads to a periodic change in contact stress.

[0006] During the use of the universal joint assembly, since a certain number of external teeth at both ends of the intermediate shaft and the same number of internal teeth of the upper joint and the lower joint cannot contact at the same time, and the torque generated by the motor is very large, there will be a situation where only part of the external teeth and part of the internal teeth are in contact, and the force acting on these parts of the external teeth and internal teeth is very large. As the motor rotates, these external teeth and internal teeth generate stress alternately, and the torque of the motor cannot be dispersed to each pair of external teeth and internal teeth, which is easy to cause fatigue fracture of the external teeth and internal teeth, resulting in premature failure of the universal joint assembly. Summary of the invention

[0007] An embodiment of the present application provides a full-time contact shock-absorbing universal joint assembly to solve the problem in the related art that a certain number of external teeth of the universal joint assembly and the same number of internal teeth of the upper joint and the lower joint cannot contact at the same time, which easily causes fatigue fracture of the external teeth and the internal teeth, leading to premature failure of the universal joint assembly.

[0008] The embodiment of the present application provides a full-time contact shock-absorbing universal shaft assembly, comprising:

[0009] A universal shaft, the universal shaft comprising an intermediate shaft and a universal joint sleeved on the end of the intermediate shaft, the end of the intermediate shaft having a plurality of spaced external teeth along the circumferential direction, the universal joint having a plurality of spaced internal teeth along the circumferential direction, the external teeth meshing with the internal teeth to achieve a variable angle transmission connection;

[0010] The elastic member, along the rotation direction of the universal shaft, the tooth surface of the outer teeth contacting the inner teeth is the outer tooth stress surface, and the tooth surface of the inner teeth contacting the outer teeth is the inner tooth stress surface. The elastic member is arranged between the outer tooth stress surface and the inner tooth stress surface so that the adjacent outer teeth and inner teeth are in full contact.

[0011] In some embodiments: the elastic member is a first disc spring.

[0012] In some embodiments: the axis of the first disc spring is perpendicular to the outer tooth stress surface or the inner tooth stress surface, and the first disc spring is provided with one or more, and the plurality of the first disc springs are located between the outer tooth stress surface and the inner tooth stress surface in a matched, overlapped or flat manner.

[0013] In some embodiments: a positioning hole for accommodating the elastic member is formed on the outer tooth stress-bearing surface and / or the inner tooth stress-bearing surface, and the elastic member is at least partially exposed outside the positioning hole.

[0014] In some embodiments: the positioning hole is a circular blind hole, and the diameter of the positioning hole is larger than the outer diameter of the elastic member.

[0015] In some embodiments: a ball seat and a ball head are provided in the universal joint, a ball socket slidably connected to the ball head is provided on the ball seat, and the ball head is movably connected between the ball seat and the intermediate shaft;

[0016] A shock absorbing element elastically connected to the universal joint is arranged at one end of the ball seat away from the ball socket, and the shock absorbing element axially elastically supports the ball seat and the universal joint to be away from each other.

[0017] In some embodiments: the shock absorbing element is a second disc spring.

[0018] In some embodiments: the axis of the second disc spring is parallel or colinear with the axis of the ball seat, and the second disc spring is provided with one or more, and the plurality of second disc springs are located between the ball seat and the universal joint in a matched, overlapped or flat manner.

[0019] In some embodiments: a mounting hole for accommodating the shock absorbing element is provided in the universal joint, and an end of the ball seat away from the ball socket is located in the mounting hole and is slidably connected to the mounting hole.

[0020] In some embodiments: an oil filling hole for injecting grease into the universal joint is opened on the side wall of the universal joint, the grease is filled between the external teeth and the internal teeth through the oil filling hole, and the oil filling hole is threadedly connected with an oil plug;

[0021] A split ring, a sealing sleeve and a locking nut are provided between the universal joint and the intermediate shaft, the split ring is located in the universal joint and abuts against the end surface of the internal teeth, and the outer wall of the locking nut is threadedly connected to the inner wall of the universal joint;

[0022] One end of the sealing sleeve is clamped between the split ring and the locking nut, and the other end of the sealing sleeve is in contact with the outer wall of the intermediate shaft. A throat clamp is sleeved on the sealing sleeve to lock the sealing sleeve on the intermediate shaft.

[0023] The beneficial effects of the technical solution provided by this application include:

[0024] An embodiment of the present application provides a full-time contact shock-absorbing universal shaft assembly. Since the full-time contact shock-absorbing universal shaft assembly of the present application is provided with a universal shaft, the universal shaft includes an intermediate shaft and a universal joint sleeved on the end of the intermediate shaft, the end of the intermediate shaft has a plurality of spaced external teeth along the circumferential direction, and the inner part of the universal joint has a plurality of spaced internal teeth along the circumferential direction, and the external teeth and the internal teeth are meshed with each other, thereby performing a variable angle transmission connection; an elastic member, along the rotation direction of the universal shaft, the tooth surface of the external teeth contacting the internal teeth is the external teeth stress surface, and the tooth surface of the internal teeth contacting the external teeth is the internal teeth stress surface, and the elastic member is arranged between the external teeth stress surface and the internal teeth stress surface, so that the adjacent external teeth and internal teeth are in full-time contact.

[0025] Therefore, the full-time contact shock-absorbing universal shaft assembly of the present application is provided with an elastic member between the external tooth stress surface and the internal tooth stress surface, and the elastic member can elastically deform to support the adjacent external tooth stress surface and internal tooth stress surface. The deformation of the elastic member can be used to make up for the gap between the external tooth stress surface of the intermediate shaft and the internal tooth stress surface of the universal joint, so that the multiple external teeth at both ends of the intermediate shaft can contact the multiple internal teeth of the universal joint at the same time. When the universal shaft rotates, the elastic member allows the external teeth at both ends of the intermediate shaft and the internal teeth of the universal joint to contact at the same time, dispersing the torque generated by the motor to the external teeth of each intermediate shaft and the internal teeth of the universal joint, reducing the contact stress of each external tooth and internal tooth, thereby increasing the service life of the universal shaft assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 This is a schematic diagram of the structure of an embodiment of the present application;

[0028] Figure 2 for Figure 1 Cross-sectional view along AA direction.

[0029] Reference numerals:

[0030] 1. Universal joint; 2. Shock absorbing element; 3. Ball seat; 4. Ball head; 5. Intermediate shaft; 6. Elastic member; 7. Split ring; 8. Sealing sleeve; 9. Locking nut; 10. Hose clamp; 11. Internal teeth; 11a. Internal teeth bearing surface; 12. Mounting hole; 13. Oil plug; 31. Ball socket; 51. External teeth; 51a. External teeth bearing surface; 51b. Positioning hole. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0032] The embodiment of the present application provides a full-time contact shock-absorbing universal joint assembly, which can solve the problem in the related art that a certain number of external teeth of the universal joint assembly and the same number of internal teeth of the upper joint and the lower joint cannot contact at the same time, which easily causes fatigue fracture of the external teeth and the internal teeth, resulting in premature failure of the universal joint assembly.

[0033] See also Figure 1 and Figure 2 As shown, the embodiment of the present application provides a full-time contact damping type universal shaft assembly, comprising:

[0034] The universal shaft includes an intermediate shaft 5 and a universal joint 1 mounted on both ends of the intermediate shaft 5. The universal joint 1 located at the top end of the intermediate shaft 5 is used to connect the motor rotor, and the universal joint 1 located at the bottom end of the intermediate shaft 5 is used to connect the transmission shaft. A universal shaft housing (not shown) is also provided outside the intermediate shaft 5 and the universal joint 1 mounted on both ends of the intermediate shaft 5.

[0035] A plurality of spaced-apart external teeth 51 are provided at the end of the intermediate shaft 1 along the circumferential direction, and a plurality of spaced-apart internal teeth 11 are provided inside the universal joint 1 along the circumferential direction. The external teeth 51 and the internal teeth 11 mesh with each other, whereby the universal joint 1 and the intermediate shaft 5 are connected in a variable angle transmission manner, thereby converting the planetary motion of the motor rotor into the fixed axis motion of the transmission shaft.

[0036] The elastic member 6, along the rotation direction of the universal shaft (clockwise rotation), the tooth surface of the external tooth 51 contacting the internal tooth 11 is the external tooth force-bearing surface 51a, and the tooth surface of the internal tooth 11 contacting the external tooth 51 is the internal tooth force-bearing surface 11a. The elastic member 6 is arranged between the external tooth force-bearing surface 51a and the internal tooth force-bearing surface 11a so that the adjacent external teeth 51 and internal teeth 11 are in contact at all times.

[0037] There is an angle between the axis of the intermediate shaft 5 with external teeth 51 at both ends and the axis of the universal joint 1, so that the gap formed between the external teeth 51 at both ends of the intermediate shaft 5 initially designed as coaxial and the internal teeth 11 of the universal joint 1 is filled by the elastic member 6 and made to contact each other, so that each external tooth 51 and internal tooth 11 can transmit the torque of the motor rotor.

[0038] In the full-time contact damping type universal shaft assembly of the embodiment of the present application, an elastic member 6 is arranged between the external tooth stress surface 51a of the external tooth 51 and the internal tooth stress surface 11a of the internal tooth 11, and the elastic member 6 can be elastically deformed to support the adjacent external tooth stress surface 51a and internal tooth stress surface 11a. The deformation of the elastic member 6 can be used to make up the gap between the external tooth stress surface 51a of the intermediate shaft 5 and the internal tooth stress surface 11a of the universal joint 1, so that the multiple external teeth 51 at both ends of the intermediate shaft 5 can contact the multiple internal teeth 11 of the universal joint 1 at the same time.

[0039] When the universal joint rotates, the elastic member 6 enables the outer teeth 51 at both ends of the intermediate shaft 5 to contact the inner teeth 11 of the universal joint 1 at the same time, dispersing the torque generated by the motor rotor to each outer tooth 51 of the intermediate shaft 5 and the inner tooth 11 of the universal joint 1, reducing the contact stress between each outer tooth 51 and the inner tooth 11, thereby increasing the service life of the universal joint assembly.

[0040] In some alternative embodiments: See Figure 1 and Figure 2 As shown, the embodiment of the present application provides a full-time contact damping type universal shaft assembly, the elastic member 6 of which is preferably but not limited to a first disc spring. The first disc spring is used to elastically support the outer tooth stress surface 51a and the inner tooth stress surface 11a.

[0041] The disc springs used in the embodiments of the present application have the following characteristics: short travel, heavy load, small space required, easy combination and use, can be used individually, or in series or in parallel, easy to repair and replace, economical, high safety, long service life, etc. In particular, the disc springs with heavy load and small space required are very suitable for the universal shaft assembly of the present application.

[0042] In some alternative embodiments: See Figure 1 and Figure 2 As shown, the embodiment of the present application provides a full-time contact damping type universal shaft assembly, the axis of the first disc spring of the full-time contact damping type universal shaft assembly is perpendicular to the external tooth force surface 51a or the internal tooth force surface 11a. The first disc spring bears static or dynamic loads acting in the axial direction at the upper inner edge and the lower outer edge, and deforms after being compressed in the axial direction until it is flattened, and acts as a live load in the form of stored energy.

[0043] The number of first disc springs in the embodiment of the present application can be one or more as needed. When multiple first disc springs are arranged between the outer tooth stress surface 51a and the inner tooth stress surface 11a, the multiple first disc springs can be located between the outer tooth stress surface 51a and the inner tooth stress surface 11a in a matching, overlapping or flat manner to adjust the elastic force between the outer tooth stress surface 51a and the inner tooth stress surface 11a.

[0044] In some alternative embodiments: See Figure 2 As shown, an embodiment of the present application provides a full-time contact shock-absorbing universal joint assembly, wherein a positioning hole 51b for accommodating an elastic member 6 is provided on the outer tooth stress surface 51a or the inner tooth stress surface 11a of the full-time contact shock-absorbing universal joint assembly, and the elastic member 6 is at least partially exposed outside the positioning hole 51b to ensure that the two ends of the elastic member 6 can contact the outer teeth 51 and the inner teeth 11 respectively, so that the elastic member 6 produces elastic deformation.

[0045] The positioning hole 51b is preferably, but not limited to, a circular blind hole, and the diameter of the positioning hole 51b is larger than the outer diameter of the elastic member 6, so that the elastic member 6 can freely produce elastic deformation in the positioning hole 51b. The height of the part of the elastic member 6 exposed outside the positioning hole 51b should be greater than the maximum distance between the outer tooth force-bearing surface 51a and the inner tooth force-bearing surface 11a.

[0046] In some alternative embodiments: See Figure 1 As shown, an embodiment of the present application provides a full-time contact shock-absorbing universal shaft assembly, in which a ball seat 3 and a ball head 4 are provided in a universal joint 1, a ball socket 31 slidably connected to the ball head 4 is provided on the ball seat 3, a ball socket 31 slidably connected to the ball head 4 is also provided at the end of the intermediate shaft 5, and the ball head 4 is movably connected between the ball seat 3 and the intermediate shaft 5.

[0047] A shock absorbing element 2 elastically connected to the universal joint 1 is provided at one end of the ball seat 3 away from the ball socket 31, and the shock absorbing element 2 axially elastically supports the ball seat 3 and the universal joint 1 to be away from each other. The shock absorbing element 2 can buffer the impact force caused by the axial clearance of the bearing on the transmission shaft and the small axial stringing of the motor rotor during the rotation process, thereby improving the service life of the screw drill.

[0048] In some alternative embodiments: See Figure 1 As shown, an embodiment of the present application provides a full-time contact shock-absorbing universal joint assembly, the shock-absorbing element 2 of the full-time contact shock-absorbing universal joint assembly is preferably but not limited to a second disc spring, and the second disc spring offsets the impact force caused by the up and down axial movement of the motor rotor, the intermediate shaft 5 and the transmission shaft through its own elastic deformation.

[0049] The disc springs used in the embodiments of the present application have the following characteristics: short travel, heavy load, small space required, easy combination and use, can be used individually, or in series or in parallel, easy to repair and replace, economical, high safety, long service life, etc. In particular, the disc springs with heavy load and small space required are very suitable for the universal shaft assembly of the present application.

[0050] The axis of the second disc spring in the embodiment of the present application is parallel or colinear with the axis of the ball seat 3. The number of second disc springs can be one or more than one as needed. When multiple second disc springs are arranged between the ball seat 3 and the universal joint 1, the multiple second disc springs are located between the ball seat 3 and the universal joint 1 in a matched, overlapped or flat manner to adjust the elastic force between the ball seat 3 and the universal joint 1.

[0051] A mounting hole 12 for accommodating the shock absorbing element 2 is provided in the universal joint 1, and one end of the ball seat 3 away from the ball socket 31 is located in the mounting hole 12 and is slidably connected to the mounting hole 12. The mounting hole 12 is used to provide a positioning and mounting space for the shock absorbing element 2 and the ball seat 3, so that the shock absorbing element 2 can be installed in a set position and direction, ensuring that the shock absorbing element 2 can reliably absorb shock in the universal joint 1.

[0052] In some alternative embodiments: See Figure 1 As shown, the embodiment of the present application provides a full-time contact damping type universal shaft assembly, and an oil injection hole for injecting grease into the universal joint 1 is provided on the side wall of the universal joint 1 of the full-time contact damping type universal shaft assembly. The grease is filled between the external teeth 51 and the internal teeth 11 through the oil injection hole to lubricate the contact surface between the external teeth 51 and the internal teeth 11, and the contact surface between the ball head 4 and the ball seat 3 and the intermediate shaft 5, and an oil plug 13 is threadedly connected to the oil injection hole.

[0053] A split ring 7, a sealing sleeve 8 and a locking nut 9 are provided between the universal joint 1 and the intermediate shaft 5. The split ring 7 is located inside the universal joint 1 and abuts against the end surface of the internal tooth 11. The outer wall of the locking nut 9 is threadedly connected to the inner wall of the universal joint 1. One end of the sealing sleeve 8 is clamped between the split ring 7 and the locking nut 9, and the other end of the sealing sleeve 8 is in contact with the outer wall of the intermediate shaft 5. A throat clamp 10 is sleeved on the sealing sleeve 8 to lock the sealing sleeve 8 on the intermediate shaft 5.

[0054] How it works

[0055] An embodiment of the present application provides a full-time contact shock-absorbing universal shaft assembly. Since the full-time contact shock-absorbing universal shaft assembly of the present application is provided with a universal shaft, the universal shaft includes an intermediate shaft 5 and a universal joint 1 sleeved on the end of the intermediate shaft 5. The end of the intermediate shaft 5 has a plurality of spaced-apart external teeth 51 along the circumferential direction, and the universal joint 1 has a plurality of spaced-apart internal teeth 11 along the circumferential direction. The external teeth 51 are meshed with the internal teeth 11, thereby performing a variable-angle transmission connection.

[0056] The elastic member 6, along the rotation direction of the universal shaft, the tooth surface of the external tooth 51 contacting the internal tooth 11 is the external tooth force-bearing surface 51a, and the tooth surface of the internal tooth 11 contacting the external tooth 51 is the internal tooth force-bearing surface 11a. The elastic member 6 is arranged between the external tooth force-bearing surface 51a and the internal tooth force-bearing surface 11a so that the adjacent external teeth 51 and internal teeth 11 are in full-time contact.

[0057] Therefore, the full-time contact damping type universal shaft assembly of the present application is provided with an elastic member 6 between the external tooth stress surface 51a and the internal tooth stress surface 11a, and the elastic member 6 can be elastically deformed to support the adjacent external tooth stress surface 51a and the internal tooth stress surface 11a. The deformation of the elastic member 6 can be used to make up the gap between the external tooth stress surface 51a of the intermediate shaft 5 and the internal tooth stress surface 11a of the universal joint 1, so that the multiple external teeth 51 at both ends of the intermediate shaft 5 can contact the multiple internal teeth 11 of the universal joint 1 at the same time.

[0058] When the universal joint rotates, the elastic member 6 enables the outer teeth 51 at both ends of the intermediate shaft 5 and the inner teeth 11 of the universal joint 1 to contact each other at the same time, dispersing the torque generated by the motor to each outer tooth 51 of the intermediate shaft 5 and the inner teeth 11a of the universal joint 1, reducing the contact stress between each outer tooth 51 and the inner tooth 11, thereby increasing the service life of the universal joint assembly.

[0059] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0060] It should be noted that, in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0061] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A full-time contact damping type universal joint shaft assembly, characterized in that: include: A universal shaft, the universal shaft comprising an intermediate shaft (5) and a universal joint (1) sleeved on the end of the intermediate shaft (5), the end of the intermediate shaft (5) having a plurality of spaced external teeth (51) along the circumferential direction, the universal joint (1) having a plurality of spaced internal teeth (11) along the circumferential direction, the external teeth (51) and the internal teeth (11) meshing with each other, thereby achieving a variable angle transmission connection; The elastic member (6) is configured such that, along the rotation direction of the universal shaft, the tooth surface of the external teeth (51) contacting the internal teeth (11) is the external teeth stress-bearing surface (51a), and the tooth surface of the internal teeth (11) contacting the external teeth (51) is the internal teeth stress-bearing surface (11a), and the elastic member (6) is arranged between the external teeth stress-bearing surface (51a) and the internal teeth stress-bearing surface (11a), so that the adjacent external teeth (51) and the internal teeth (11) are in full-time contact; The elastic member (6) is a first disc spring; The axis of the first disc spring is perpendicular to the outer tooth stress surface (51a) or the inner tooth stress surface (11a), and one or more first disc springs are provided, and the plurality of first disc springs are located between the outer tooth stress surface (51a) and the inner tooth stress surface (11a) in a manner of matching, overlapping or laying flat; The outer tooth stress-bearing surface (51a) and / or the inner tooth stress-bearing surface (11a) are provided with a positioning hole (51b) for accommodating the elastic member (6), and the elastic member (6) is at least partially exposed outside the positioning hole (51b); The positioning hole (51b) is a circular blind hole, and the diameter of the positioning hole (51b) is greater than the outer diameter of the elastic member (6).

2. A full-time contact damping type universal joint shaft assembly as claimed in claim 1, characterized in that: The universal joint (1) is provided with a ball seat (3) and a ball head (4); the ball seat (3) is provided with a ball socket (31) slidably connected to the ball head (4); the ball head (4) is movably connected between the ball seat (3) and the intermediate shaft (5); The end of the ball seat (3) away from the ball socket (31) is provided with a shock absorbing element (2) elastically connected to the universal joint (1), and the shock absorbing element (2) axially elastically supports the ball seat (3) and the universal joint (1) to be away from each other.

3. A full-time contact damping type universal joint shaft assembly as claimed in claim 2, characterized in that: The shock absorbing element (2) is a second disc spring.

4. A full-time contact damping type universal joint shaft assembly as claimed in claim 3, characterized in that: The axis of the second disc spring is parallel or colinear with the axis of the ball seat. One or more second disc springs are provided, and the plurality of second disc springs are located between the ball seat (3) and the universal joint (1) in a matched, overlapped or flat manner.

5. A full-time contact damping type universal joint shaft assembly as claimed in claim 2 or 3, characterized in that: The universal joint (1) is provided with a mounting hole (12) for accommodating the shock absorbing element (2); an end of the ball seat (3) away from the ball socket (31) is located in the mounting hole (12) and is slidably connected to the mounting hole (12).

6. A full-time contact damping type universal joint shaft assembly as claimed in claim 2, characterized in that: An oil injection hole for injecting grease into the universal joint (1) is provided on the side wall of the universal joint (1), and the grease is filled between the external teeth (51) and the internal teeth (11) through the oil injection hole, and the oil injection hole is threadedly connected to an oil plug (13); A split ring (7), a sealing sleeve (8) and a locking nut (9) are provided between the universal joint (1) and the intermediate shaft (5); the split ring (7) is located inside the universal joint (1) and abuts against the end surface of the internal tooth (11); the outer wall of the locking nut (9) is threadedly connected to the inner wall of the universal joint (1); One end of the sealing sleeve (8) is clamped between the split ring (7) and the locking nut (9), and the other end of the sealing sleeve (8) is in contact with the outer wall of the intermediate shaft (5). A throat clamp (10) is sleeved on the sealing sleeve (8) to lock the sealing sleeve (8) on the intermediate shaft (5).

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