A lightweight universal joint, spline matching pair and transmission shaft

Abstract

The present invention discloses a lightweight universal joint, a spline mating pair and a transmission shaft, and relates to the field of automobile transmission shafts. The lightweight universal joint includes a ball socket, a ball head and a straight shaft. The ball socket is a thin-walled structure, and the ball socket is no longer used to transmit transmission torque; the ball head is hingedly installed in the ball socket, and a transmission hole is provided on the ball head. The straight shaft passes through the transmission hole. Both ends of the ball socket are connected with fixed wings, and the fixed wings are provided with bearing holes and transmission keys. The lightweight spline mating pair includes a spline shaft and a spline sleeve, and the spline shaft and the spline sleeve are both thin-walled structures. The lightweight transmission shaft includes the lightweight universal joint, and / or the lightweight spline mating pair. The present invention realizes non-cutting processing by integrally forming the ball socket and the spline mating pair with thin-walled structures, greatly improving production efficiency and quality stability, greatly reducing part weight and processing costs, and meeting the lightweight development requirements of automobile parts.

Description

Technical Field

[0001] The present invention relates to the field of automobile transmission shafts, and in particular to a lightweight universal joint, a spline fitting pair and a transmission shaft. Background Art

[0002] This application is a further optimization and improvement based on the Chinese patent technology CN202021793026.3, application date: 2020-08-20, publication number: CN213176523U, and is an improvement made to meet the requirements of the automotive industry for lightweight drive shafts. In order to achieve lightweight, the drive shafts of the existing technology generally use lightweight materials such as aluminum alloys and carbon fibers to achieve the purpose of reducing the weight of parts. However, such lightweight materials are generally expensive, which increases the cost of the drive shaft and increases the difficulty of production. The process is complicated and there are still technical deficiencies. There are also quality risks in the connection between carbon fiber and steel. Delamination is prone to occur between different materials, thereby reducing product strength and causing quality accidents. Compared with the traditional cross-axis drive shaft, Chinese patent technology CN202021793026.3 has reduced weight, but the ball socket processing technology is complex, the processing efficiency is low, the processing cost is high, and it is difficult to achieve standardization. In addition, since the ball socket is a key load-bearing component and bears the function of transmitting torque, the overall force is relatively large, requiring a high structural strength. The wall thickness and weight of the part are difficult to further reduce. The weight is heavy and cannot meet the requirements of mass production and lightweighting of automotive drive shafts. In addition, the huge torque borne by the ball socket can easily cause deformation of the main structure of the ball socket, which will further affect the fitting accuracy of the parts. There is a need for further structural optimization to achieve the goals of reducing weight, simplifying the process, improving production efficiency and processing quality stability, improving product performance, and reducing product costs. At the same time, the manufacturing process of the splined mating pair of the spline sleeve and spline shaft of the existing drive shaft is also relatively complex and heavy, which requires improvement. Summary of the Invention

[0003] The main purpose of the present invention is to provide a lightweight universal joint, a spline mating pair and a drive shaft to meet the requirements of the automotive industry for lightweight and standardization of drive shafts, and at the same time solve the problems of patent technology CN202021793026.3, such as high cost, complex processing technology, low processing efficiency, and inability to adapt to the requirements of mass production of automobile drive shafts; at the same time, optimize the stress state and function of the universal joint and the ball socket, so that the ball socket body no longer transmits torque, and mainly assumes the function of sealing lubricating oil, thereby reducing the stress deformation of the ball socket, improving the structural process of the ball socket, reducing the manufacturing difficulty, improving the processing efficiency of the ball socket, and reducing the weight and processing cost of the ball socket; optimize the structural process of the spline sleeve and the spline shaft, through large diameter and small wall thickness, optimize the material distribution, maximize the material properties, improve the spline bearing capacity, reduce the stress and sliding friction of the spline, reduce the spline wear, improve the spline life, reduce the weight of the spline mating pair, simplify the manufacturing process of the spline mating pair, improve production efficiency, reduce product cost, and improve product quality.

[0004] In order to solve the above-mentioned problems existing in the transmission shaft of the prior art, the present invention provides a lightweight universal joint, including a ball socket, a ball head, and a straight shaft. The ball socket is a thin-walled structure, and the ball socket is no longer used to transmit transmission torque; the ball head is rotatably installed in the ball socket, and a transmission hole is provided on the ball head. The straight shaft passes through the transmission hole and passes through the center of the ball head. Fixed wings are connected to both ends of the ball socket, and a bearing hole and a transmission key are provided on the fixed wings.

[0005] In this invention, the main body of the ball socket no longer transmits torque; its primary function is to provide a sealed, lubricated space for other transmission components within the socket. This significantly improves the stress state of the universal joint and addresses the existing technical issues of conventional universal joints, where the main body of the ball socket is required to transmit torque, resulting in relatively high stress on the entire socket and the tendency for high torque to cause deformation of the socket structure. Furthermore, by connecting the fixed wing to the external component, changes in the external component's connection dimensions can be accommodated by adjusting the fixed wing. This eliminates the impact of external connection dimensional changes on the ball socket structure, allowing standardized mass production of the core ball socket component to meet the high-volume production requirements of automobiles.

[0006] Furthermore, the ball socket is an integral thin-walled one-piece molded structure or a split thin-walled structure.

[0007] Furthermore, it also includes rolling bodies, which are arranged at both ends of the straight shaft, and raceway surfaces are arranged at both ends of the transmission hole. The outer surface of the rolling body cooperates with the raceway surface of the transmission hole to transmit torque. The rolling body can rotate around the axis of the straight shaft and can roll on the raceway surface of the transmission hole.

[0008] Furthermore, the outer surface of the rolling body is a conical surface, the conical surface of the rolling body cooperates with the raceway surface of the transmission hole, the contact generatrix of the two is a straight line, and the extension line of the contact generatrix passes through the center of the ball head.

[0009] Furthermore, a limiting mechanism is included, and the limiting mechanism is used to axially limit the rolling element.

[0010] Furthermore, it also includes an axial support mechanism for axially supporting and positioning the straight shaft.

[0011] Furthermore, the axial support mechanism shown is a steel ball or a friction pad.

[0012] Furthermore, the ball socket is an integral thin-walled integrally formed structure, a plug hole is symmetrically provided on the ball socket, a plug interface is provided on the fixed wing, the plug interface is plugged into the plug hole, and the straight shaft is rotatably supported on the bearing hole of the fixed wing.

[0013] Furthermore, the ball socket is an integrally-molded structure.

[0014] Furthermore, the ball socket is a split structure, including a ball socket I and a ball socket II. The ball socket I and the ball socket II are both integrally formed thin-walled structures. The ball socket I and the ball socket II are interconnected and symmetrically arranged.

[0015] Furthermore, both the ball socket I and the ball socket II are provided with an inner spherical surface, a bearing hole and a fixing cylinder, the fixing wing is connected to the fixing cylinder through the bearing hole, and the straight shaft is rotatably supported on the bearing hole.

[0016] Furthermore, a sealing fixing surface is provided on the ball socket I and the ball socket II respectively, and a sealing groove is provided on the sealing fixing surface and a sealing ring is placed thereon to achieve a sealed connection between the ball socket I and the ball socket II.

[0017] Furthermore, the wall thickness of the ball socket is 0.2-5 mm.

[0018] Furthermore, the diameter of the lip of the ball socket is smaller than the ball diameter of the ball head.

[0019] Furthermore, a positioning spherical surface is provided at the middle portion of the straight shaft, a constraint surface is provided at the middle portion of the transmission hole of the ball head, and the positioning spherical surface is constrained to fit within the constraint surface of the transmission hole.

[0020] The present invention also provides a lightweight spline fitting pair, comprising a spline shaft and a spline sleeve, wherein the spline shaft and the spline sleeve are both thin-walled structures, and the spline shaft and the spline sleeve form a slidable spline fitting pair through spline fitting.

[0021] Existing spline pairs typically feature small diameters and large wall thicknesses. By appropriately increasing the spline pitch diameter while reducing the wall thickness, we optimize the diameters and wall thicknesses of the spline shaft and sleeve, optimizing material distribution, minimizing material utilization, and maximizing material performance. This large diameter and small wall thickness improves the spline's load-bearing capacity, reduces stress and sliding friction, reduces wear, increases spline life, and enhances spline performance. Furthermore, the design is more suitable for advanced cold forming and non-cutting machining processes, reducing processing costs and improving product quality.

[0022] Furthermore, an internal spline is provided at one end of the spline shaft, and the spline shaft is fixedly connected to the external spline corresponding to the ball head handle at one end of the transmission shaft through the internal spline; an external spline is also provided on the outside of the spline shaft, and the external spline on the spline shaft is slidably fitted with the internal spline provided at one end of the spline sleeve, and the other end of the spline sleeve is fixedly connected to the external spline corresponding to the ball head handle at the other end of the transmission shaft through its internal spline.

[0023] Furthermore, it also includes a spline oil storage cylinder, which is nested in the inner cavity of the spline shaft to form an oil storage cavity. The spline shaft is provided with a plurality of oil distribution holes, which are communicated with the oil storage cavity.

[0024] Furthermore, the internal splines and external splines of the spline shaft and the spline sleeve are involute splines, rectangular splines, or plum blossom splines.

[0025] The present invention also provides a lightweight transmission shaft, comprising a universal joint and / or a spline mating pair, wherein the universal joint is the aforementioned lightweight universal joint, and / or the spline mating pair is the aforementioned lightweight spline mating pair.

[0026] Furthermore, a sealing port is provided on the ball socket of the lightweight universal joint, and a dust cover is connected to the sealing port. One end of the dust cover is connected to the sealing port, and the other end is connected to the handle of the ball head or the spline sleeve of the transmission shaft.

[0027] Furthermore, the ball socket and the dust cover are an integrally formed structure.

[0028] Furthermore, a filter is provided at one end of the dust cover connected to the spline sleeve or the handle of the ball head, and an exhaust hole is provided on the ball head. The inner cavity of the dust cover is connected to the central cavity of the spline mating pair through the exhaust hole, and external air can enter the inner cavity of the dust cover after being filtered through the filter.

[0029] The present invention has the following beneficial effects:

[0030] 1. The ball and socket and spline mating pairs are both integrally formed with a thin-wall structure, achieving no or minimal cutting processing. This not only significantly improves production efficiency and quality stability, reduces weight by about 40-70%, saves a large amount of steel, meets the lightweight development requirements of automotive parts, but also significantly improves product performance and reduces the vibration and noise of the drive shaft.

[0031] 2. The ball socket is connected to the external part through the fixed wing. When the connection size of the external part changes, it can be adapted by changing the fixed wing, so that the change of the external connection size no longer affects the structure of the ball socket, and the standardized mass production of the ball socket can be realized, which meets the mass production requirements of automobiles.

[0032] 3. The stress state of the universal joint is completely improved through structural optimization design, so that torque transmission is mainly completed through the fixed wing, bearing, straight shaft, rolling element and ball head. The main structure of the ball socket no longer bears the task of transmitting torque. The ball socket mainly serves the function of oil storage and sealing, which fundamentally reduces the load on the ball socket. As a result, the ball socket can achieve a lighter structural design such as injection molding or stamping, saving material utilization, improving product performance and quality, and reducing costs.

[0033] 4. The ball socket is injection molded and the spline mating pair is cold formed, which eliminates the original complicated cutting process, not only improving the processing quality of the parts, but also saving a lot of processing costs and extending the product life.

[0034] 5. The spline oil storage cylinder lubrication structure design distributes the lubricating oil evenly on the inner surface of the spline part of the spline shaft, which can make the lubricating oil more evenly and reliably distributed on the sliding surface of the spline mating pair under the action of the rotating centrifugal force. At the same time, it can prevent the lubricating oil from piling up or deviating to one side to cause eccentricity and affect the dynamic balance of the transmission shaft, thereby improving the utilization efficiency of the lubricating oil.

[0035] 6. The cooperation between the positioning spherical surface of the straight shaft and the restraining surface in the middle part of the ball head transmission hole can transfer the axial pull-out force of the ball head to the positioning spherical surface of the straight shaft through the restraining surface, effectively reducing the centering load of the ball socket, allowing the universal joint to bear a greater ball head pull-out force, strengthening the centering ability, effectively protecting the ball socket, and increasing the life of the ball socket.

[0036] 7. The setting of the limiting mechanism of the rolling element can transfer the axial force on the rolling element to the straight shaft. Since the rolling elements are arranged symmetrically, the axial force becomes a pair of equal and opposite balanced forces acting on the straight shaft, thereby avoiding damage to other components by the force and making the overall structure of the universal joint more balanced and reasonable.

[0037] 8. The axial support mechanisms set at both ends of the straight shaft can provide axial support for the straight shaft, and further provide axial support and centering for the ball head through the rolling elements, while sharing the supporting force of the ball socket on the ball head, thereby improving the ability of the universal joint to resist vibration wear.

[0038] 9. The present invention can solve the problems of high cost, complex process and quality risks in high-end transmission shafts such as aluminum alloy / carbon fiber in the prior art.

[0039] 10. The present invention breaks through the limitations of the existing technology in structure and manufacturing process, subverts the design ideas and process routes of the existing transmission shaft, and opens up a new design concept and development idea for the transmission shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A front view of a first embodiment of a lightweight universal joint according to the present invention;

[0041] Figure 2 for Figure 1 EE cross-sectional view;

[0042] Figure 3 for Figure 2 The cap is equivalently replaced by a retaining ring and a steel ball;

[0043] Figure 4 for Figure 2 The limiting mechanism in the diagram is replaced by a bolt equivalent to a retaining ring;

[0044] Figure 5 for Figure 1 FF cross-sectional view;

[0045] Figure 6 for Figure 1 A magnified view of point A;

[0046] Figure 7 It is a three-dimensional schematic diagram of a ball head, and the handle of the ball head has splines;

[0047] Figure 8 for Figure 1 Schematic diagram of the three-dimensional structure assembly of the lightweight universal joint;

[0048] Figure 9 for Figure 1 Schematic diagram of the three-dimensional structure of the ball socket, wherein (a) is a front perspective view of the ball socket, and (b) is a rear perspective view of the ball socket;

[0049] Figure 10 for Figure 1 Schematic diagram of the three-dimensional structure of the fixed wing, where (a) is a top-down perspective view of the fixed wing, and (b) is a bottom-down perspective view of the fixed wing;

[0050] Figure 11 It is a structural schematic diagram of a second embodiment of a lightweight universal joint;

[0051] Figure 12 for Figure 11 BB cross-sectional view;

[0052] Figure 13 This is a schematic diagram of the structure of the friction pad as an axial support mechanism;

[0053] Figure 14 Schematic diagram of the structure of the bolt as a limiting mechanism;

[0054] Figure 15 for Figure 11 CC cross-sectional view;

[0055] Figure 16 for Figure 11 DD cross-sectional view;

[0056] Figure 17 for Figure 11 Schematic diagram of the three-dimensional structure of the ball socket, wherein (a) is a bottom-up three-dimensional diagram of the ball socket, and (b) is a top-down three-dimensional diagram of the ball socket;

[0057] Figure 18 for Figure 11 Schematic diagram of the three-dimensional structure of the fixed wing, where (a) is a top-down perspective view of the fixed wing, and (b) is a bottom-down perspective view of the fixed wing;

[0058] Figure 19 for Figure 11 Schematic diagram of the three-dimensional structure of the lightweight universal joint, with the fixed wing omitted in the figure;

[0059] Figure 20 It is a structural schematic diagram of the third embodiment of the lightweight universal joint;

[0060] Figure 21 for Figure 20 HH cross-sectional view;

[0061] Figure 22 A three-dimensional diagram of the spline shaft and spline sleeve Figure 1 , wherein (a) is a three-dimensional schematic diagram of a spline shaft, and (b) is a three-dimensional schematic diagram of a spline sleeve;

[0062] Figure 23 A three-dimensional diagram of the spline shaft and spline sleeve Figure 2 , wherein (a) is a three-dimensional schematic diagram of a spline shaft, and (b) is a three-dimensional schematic diagram of a spline sleeve;

[0063] Figure 24 It is a structural schematic diagram of a first embodiment of the transmission shaft;

[0064] Figure 25 It is a structural schematic diagram of a second implementation scheme of the transmission shaft;

[0065] Figure 26 for Figure 24 QQ sectional view, in which the spline shaft and spline sleeve are Figure 22 The splined shaft and splined hub shown;

[0066] Figure 27 for Figure 24 JJ sectional view;

[0067] Figure 28 for Figure 25 KK sectional view, in which the spline shaft and spline sleeve are Figure 23 The splined shaft and splined hub shown;

[0068] Figure 29 for Figure 28 LL cross-sectional view;

[0069] Figure 30 It is a structural schematic diagram of a third embodiment of the transmission shaft;

[0070] Figure 31 A three-dimensional diagram of the spline shaft and spline sleeve Figure 3 , wherein (a) is a three-dimensional schematic diagram of a spline shaft, and (b) is a three-dimensional schematic diagram of a spline sleeve;

[0071] Figure 32 Schematic diagram of the structure of the fourth implementation scheme of the transmission shaft. DETAILED DESCRIPTION

[0072] The present invention will be further described below with reference to the accompanying drawings.

[0073] Example 1:

[0074] like Figure 1 、 Figure 11 and Figure 20 As shown in FIG. 1 , a lightweight universal joint of the present invention comprises a ball socket 3, a ball head 1, and a straight shaft 2. The ball socket 3 is a thin-walled structure. The ball head 1 is rotatably mounted in the ball socket 3. A transmission hole is provided on the ball head 1. The straight shaft 2 passes through the transmission hole. Fixed wings 8 are connected to both ends of the ball socket 3. Figure 10 As shown, the fixed wing 8 is provided with a bearing hole 8-1 and a transmission key 8-2.

[0075] Specifically, the ball head 1 is rotatably mounted in the ball socket 3 and rotatably mounted on the straight shaft 2 through a transmission hole. The ball socket is provided with an inner spherical surface Q. The outer surface of the ball head 1 rotates concentrically with the inner spherical surface Q of the ball socket 3. A fixed wing 8 is installed at each end of the ball socket 3. The transmission key 8-2 on the fixed wing 8 is connected to the input or output port of the transmission system. The fixed wing 8 receives the torque transmitted from the end of the straight shaft and transmits it to the transmission system connected thereto through the transmission key 8-2. Alternatively, the fixed wing 8 receives the torque transmitted from the transmission system connected thereto through the transmission key 8-2, and then transmits it to the end of the straight shaft, whereupon the torque is transmitted to the ball head 1 through the straight shaft, thereby realizing universal joint power transmission. In this power transmission mode, the ball socket 3 body no longer transmits the transmission torque, and its main function is to provide a closed lubrication space for other transmission components in the ball socket 3. Therefore, by installing fixed wings at both ends of the ball socket 3 for transmitting torque, the present invention solves the existing technical problem that the main structure of the ball socket of a conventional universal joint needs to transmit torque, resulting in a relatively large force on the ball socket 3 as a whole, and high torque easily leads to deformation of the ball socket structure. This significantly improves the stress state of the universal joint. Furthermore, by connecting the fixed wings to the external parts, changes in the connection dimensions of the external parts can be accommodated by changing the fixed wings. This eliminates the impact of changes in the external connection dimensions on the ball socket structure, allowing standardized mass production of the core ball socket component to meet the high-volume production requirements of automobiles.

[0076] The ball socket of the present invention is a thin-walled structure, and the ball socket of the thin-walled structure is made by injection molding, compression molding, stretching molding and other non-cutting processing techniques, which simplifies the manufacturing. However, since the main structure of the ball socket of the traditional universal joint needs to transmit torque, the ball socket must have a thicker wall thickness to ensure its structural strength, and the traditional ball socket processing cost is high. The present invention reduces the wall thickness of the ball socket, which greatly reduces the weight of the component. The lightweight universal joint of the present invention completely improves the stress state of the universal joint through structural optimization design, so that the torque transmission is mainly completed through the fixed wing, bearing, straight shaft, rolling body and ball head. The ball socket mainly assumes the function of oil storage and sealing, which fundamentally and significantly reduces the load of the ball socket, thereby realizing a light and thin structural design of the ball socket, saving materials, improving product performance and quality, and reducing costs.

[0077] Further, if Figure 1 、 Figure 11 and Figure 20As shown, the universal joint of the present invention also includes a rolling body 7, which is provided with a conical surface 7-2 and a fixed surface 7-1. The transmission hole of the ball head 1 passes through the ball head and is symmetrically arranged along the center planes CC, FF and NN of the ball head. The axis of the transmission hole passes through the center of the ball head 1, and the two ends of the transmission hole are raceway surfaces 1-1. The rolling body 7 is symmetrically and coaxially assembled on the straight shaft 2. The conical surface 7-2 of the rolling body 7 cooperates with the raceway surface 1-1 of the transmission hole of the ball head 1. The contact generatrix M of the two is a straight line, and the extension line of the contact generatrix M passes through the center of the ball head 1 R. The rolling body 7 can roll around the center of the ball head 1 along the surface of the transmission hole raceway surface 1-1; the two symmetrically arranged rolling bodies 7 also serve as the inner rings of the bearings, and respectively cooperate with the bearings 9 at both ends of the straight shaft through their fixed surfaces 7-1, and are further fixed to the bearing hole G of the ball socket 3 or the bearing hole of the fixed wing through the bearing 9. The ball socket 3 is wrapped around the outer spherical surface of the ball head 1 through its inner spherical surface Q.

[0078] Further, if Figure 1 、 Figure 11 and Figure 20 As shown, the ball socket 3 is also provided with a sealing port T. One end of the dust cover 11 is connected to the sealing port T of the ball socket 3, and the other end is fixedly wrapped around the handle of the ball head 1 (including the extension part fixedly connected to the ball head 1, such as the shaft tube, etc.) or the spline sleeve, thereby forming a sealed space between the dust cover and the ball socket. The ball head part, rolling element, straight shaft, and bearing of the ball head 1 are wrapped and sealed together, and grease is added at the same time.

[0079] Further, if Figure 2-4 As shown in 12-14, a limiting mechanism is provided at both ends of the straight shaft, and the limiting mechanism is used to limit the axial position of the rolling element 7.

[0080] Figure 2-3 12-13 show an implementation of the limiting mechanism, which includes a retaining ring groove and a retaining ring 5. The retaining ring grooves are arranged at both ends of the straight shaft 2, and the retaining ring 5 is clamped in the retaining ring grooves.

[0081] Furthermore, the retaining ring is an open elastic retaining ring, which is clamped in the retaining ring groove of the straight shaft through the retaining ring's own elasticity after assembly.

[0082] Further, if Figure 8 As shown, for the convenience of assembly, the retaining ring 5 is a split semi-annular structure. The retaining rings 5 used in pairs can form a complete annular retaining ring, which is stuck in the retaining ring grooves at both ends of the straight shaft 2. The two semi-annular retaining rings 5 used in pairs can be tightly clamped together by a tightening device to prevent the retaining ring 5 from falling out of the retaining ring groove of the straight shaft 2. Figure 1 and Figure 8The tightening device shown is a cap 24, which is mounted on the end of the straight shaft and constrains the two semi-annular retaining rings 5 used in pair in the cylindrical inner cavity of the cap 24. Figure 11-13 、 Figure 19 The tightening device shown is a retaining spring 6. An annular groove is provided on the outer circumference of the retaining ring 5. The retaining spring 6 can be sleeved in the annular groove of the retaining ring 5, thereby tightening the two semi-annular retaining rings 5 used in pairs together. Equivalently, the retaining spring 6 can also be replaced by an iron wire, by which the two retaining rings 5 used in pairs are wound and tightened together. The cap 24 can also be a tubular structure with openings at both ends, which will not be described in detail here. The limiting structure supports the symmetrically arranged rolling bodies 7 between the retaining rings 5 at both ends of the straight shaft 2, restricting the outward movement of the rolling bodies 7 along the axis of the straight shaft, and bearing the axial force along the axis direction of the straight shaft generated when the rolling bodies are driven. Of course, the retaining ring 5 can also be equivalently replaced by other structures such as a retaining column and a baffle.

[0083] Figure 4 and Figure 14 Another embodiment of a limiting mechanism is shown. The limiting mechanism includes a bolt X and internal threads formed at both ends of a straight shaft 2, with the bolt X being secured to both ends of the straight shaft 2 via the internal threads. Alternatively, the limiting mechanism includes a nut and external threads formed at both ends of the straight shaft 2, with the nut being secured to both ends of the straight shaft 2 via the external threads. Specifically, internal or external threads are provided at both ends of the straight shaft 2, and the bolt or nut is screwed onto the threads at both ends of the straight shaft, thereby clamping the symmetrically arranged rolling elements 7 between the bolts or nuts at both ends of the straight shaft, limiting the outward movement of the rolling elements 7 along the straight shaft axis and absorbing the axial force generated along the straight shaft axis during rolling element transmission.

[0084] The limiting mechanism transfers the axial force generated by the rolling element transmission to the straight shaft. Due to the symmetrical arrangement of the rolling elements, this axial force is transformed into a pair of equal and oppositely balanced forces acting on the straight shaft, thus preventing damage to other components and ensuring a more balanced and rational force distribution throughout the universal joint. After enduring this axial tensile force, the straight shaft's ability to withstand bending and torsion is enhanced, improving its stress state.

[0085] Further, if Figure 5 and Figure 15 As shown, a lip K is provided on the ball socket 3, and the diameter of the lip K is smaller than the ball diameter of the ball head.

[0086] Preferably, the wall thickness of the ball socket is 0.2-5 mm.

[0087] Further, if Figure 1 、 6As shown in Figure 11, the middle part of the straight shaft 2 is provided with a positioning spherical surface 2-1, and the middle part of the ball head transmission hole is provided with a constraint surface 1-2. After the straight shaft 2 passes through the transmission hole of the ball head, its positioning spherical surface 2-1 cooperates with the constraint surface 1-2 of the transmission hole, and the constraint surface 1-2 limits the position of the positioning spherical surface 2-1. Figure 6 As shown, the positioning spherical surface 2 - 1 is a spherical surface protruding from the outer surface of the straight shaft 2 .

[0088] The cooperation between the positioning spherical surface 2-1 of the straight shaft and the restraining surface 1-2 in the middle of the ball head transmission hole can enable the straight shaft to directly bear the ball head pull-out force, strengthen the centering ability, effectively protect the ball socket, and increase the life of the ball socket.

[0089] Further, if Figure 20-21 As shown, a hinge pin Y can also be provided. A hinge hole 2-2 is provided in the middle of the straight shaft 2, with the axis of the hinge hole 2-2 perpendicularly intersecting the axis of the straight shaft 2. A fixing hole 1-3 is provided on the ball head 1, with the axis of the fixing hole 1-3 passing through the center R of the ball head 1 and perpendicular to the center plane CC of the ball head. The hinge pin Y passes through the fixing hole 1-3 of the ball head and is hinged to the hinge hole 2-2 of the straight shaft, allowing the straight shaft to swing around the axis of the hinge pin Y within the transmission hole of the ball head. The structural arrangement of the hinge pin further enhances the centering effect.

[0090] Furthermore, axial support mechanisms are provided at both ends of the straight shaft 2. Figure 2-4 , 11-14, the axial support mechanism is a cap 24, a steel ball or a friction pad P. Note: When the axial support mechanism is the cap 24, the cap 24 serves as both a clamping device for the semi-annular retaining ring 5 and an axial support mechanism. Specifically, as Figure 11-14 The steel ball or friction pad P is arranged between the end of the straight shaft 2 and the bottom of the bearing hole G, or as Figure 2-4 As shown, a steel ball or a friction pad P is provided between the end of the straight shaft 2 and the top of the inner cavity of the fixed wing 8 for axially supporting the straight shaft.

[0091] The axial support mechanisms provided at both ends of the straight shaft, namely the steel balls 4 or the wear-resistant pads P, can provide axial support for the straight shaft, and further provide axial support and centering for the ball head through the rolling elements, while sharing the supporting force of the ball socket on the ball head, thereby improving the ability of the universal joint to resist vibration wear.

[0092] The positioning spherical surface 2-1 of the straight shaft and the axial support mechanism and the limiting mechanism and the rolling body 7 provided at both ends of the straight shaft 2 can jointly constrain and position the ball head so that the ball head remains in the correct fitting position.

[0093] Example 2:

[0094] like Figure 11-17 , Figure 19 As shown, the ball socket 3 is a split thin-walled structure, which is divided into two parts, ball socket I 31 and ball socket II 32. Ball socket I 31 and ball socket II 32 are symmetrically arranged and sealed, and are combined into a space for accommodating the ball head part of the ball head 1 and the straight shaft 2, rolling element 7 and bearing. Both ball socket I 31 and ball socket II 32 are provided with an inner spherical surface Q, a bearing hole G and a fixing cylinder S. The fixing wing 8 wraps and clamps the fixing cylinder S of the corresponding ball socket through the bearing hole 8-1, and the transmission torque is transferred through the fixing cylinder S, so that the ball socket body no longer bears the function of transmitting torque.

[0095] Preferably, the ball socket I 31 and the ball socket II 32 are both thin-walled parts formed in one piece and are symmetrically arranged along the center plane CC of the ball head. Figure 17 As shown, each of the sockets I 31 and II 32 is provided with a sealing fixing surface 12, which securely connects the sockets I 31 and II 32 to form a single-piece socket. In one embodiment, the sealing fixing surface 12 is further provided with a sealing groove 14, which is an annular groove recessed from the surface of the sealing fixing surface. When the sealing fixing surfaces 12 of the sockets I 31 and II 32 are fitted together, the sealing grooves 14 of the sockets I 31 and II 32 form a sealed cavity. A sealing ring 15 is placed in the sealed cavity. The sealing ring 15 is squeezed by the sealing grooves 14 of the sockets I 31 and II 32, thereby forming a seal between the sealing fixing surfaces of the sockets I 31 and II 32. Together with the dust cover 11, the sealing ring 15 forms a complete sealing structure of the universal joint. Of course, the sealing fixing surface 12 of the ball socket I 31 and the sealing fixing surface 12 of the ball socket II 32 can also adopt a concave-convex sealing fit (such as setting a protrusion on one sealing fixing surface and a groove on the other sealing fixing surface, and the protrusion and the groove are sealed together), a plane sealing fit (such as setting a sealing gasket between the two sealing fixing surfaces and applying sealant), etc.

[0096] Preferably, the sealing fixing surfaces of the ball socket I 31 and the ball socket II 32 can be fixedly connected by rivets 13 , bolted connection, welding, etc. as needed.

[0097] Example 3:

[0098] like Figure 1-5 , Figure 8-9 As shown, the ball socket 3 is an integral thin-walled integrally formed structure, that is, the main body of the ball socket is an integral thin-walled integrally formed structure, and the two ends of the ball socket 3 are symmetrically provided with plug holes 3-1, and the fixed wing 8 is also provided with a plug interface 8-3, and the plug interface 8-3 of the fixed wing 8 is sealed and plugged into the plug hole 3-1 of the ball socket. Preferably, an oil seal groove is provided at the mouth of the plug hole 3-1, and the sealing ring 27 is compressed and placed between the oil seal groove and the plug interface to form a reliable seal (as shown in FIG. Figure 1 As shown), the bearing hole 8-1 of the fixed wing 8 is used to support the fixed bearing 9.

[0099] The main body of the ball socket 3 can be integrally formed with a thin steel plate, or can be made of non-metallic materials such as resin, nylon, plastic, etc.

[0100] When the ball socket 3 is made of an elastic material, a steel frame can be pre-embedded in the socket 3's insertion hole 3-1. This allows the socket 3 to be integrated with the steel frame when the main body of the ball socket 3 is integrally formed from the elastic material. This provides rigidity for the insertion hole 3-1, which then forms an interference fit with the insertion interface 8-3 of the fixed wing 8, improving the sealing and reliability of the connection. Furthermore, the insertion hole 3-1 of the ball socket 3 must be securely connected to the insertion interface 8-3 of the fixed wing 8 and secured with a clamp or other means.

[0101] Preferably, the sealing port T of the ball socket is fixedly connected to the dust cover 11. The ball socket and the dust cover can be manufactured as two separate parts, and then fixed together through the sealing port T of the ball socket and the connecting port of the dust cover 11 by means of a clamp or the like. The dust cover and the ball socket can also be integrally formed into an integral part.

[0102] like Figure 20 As shown, when the ball socket and the dust cover 11 are an integrally formed structure and the material used is a soft elastic material, the insertion hole 3-1 of the ball socket can increase the rigidity of the ball socket bearing hole by pre-embedded steel frame to facilitate assembly.

[0103] Example 4:

[0104] like Figure 22 、 Figure 24 、 26 -27 shows a lightweight spline mating pair, including a spline shaft 16 and a spline sleeve 17. Both the spline shaft 16 and the spline sleeve 17 are thin-walled structures. The spline shaft 16 and the spline sleeve 17 are fitted together by the concave and convex shapes of the mating surfaces to form a slidable spline mating pair. By appropriately increasing the diameter of the spline pitch circle and reducing the wall thickness, the diameter and wall thickness of the spline shaft and the spline sleeve are optimized, the material distribution is optimized, the bearing capacity of the spline is improved, and the stress and sliding friction of the spline are reduced.

[0105] Furthermore, it also includes a spline oil storage cylinder 22, which is nested in the inner cavity of the spline shaft 16. One end of the spline shaft is fixedly connected to the ball head, and the other end is connected to one end of the spline oil storage cylinder, and the other end of the spline oil storage cylinder is connected to the ball head, thereby forming an oil storage chamber 23 among the spline oil storage cylinder 22, the spline shaft 16 and the ball head. The spline shaft 16 is provided with a plurality of oil distribution holes 16-2, and the oil distribution holes 16-2 are communicated with the oil storage chamber 23. The lubricating oil is stored in the oil storage chamber. When the transmission shaft rotates at high speed, the lubricating oil in the oil storage chamber can reach the sliding mating surface of the spline shaft and the spline sleeve through the oil distribution holes provided on the spline shaft under the action of the rotating centrifugal force, thereby lubricating the spline mating pair.

[0106] Specifically, the spline shaft 16 and the spline sleeve 17 are both thin-walled structures, and a concave and convex spline structure is formed on the surface of the thin-walled round tube by cold drawing or die pressing, forming a sliding spline pair. One end of the spline pair is matched with the handle spline of the universal joint ball head through the spline shaft and welded and reinforced, and the other end of the spline pair is matched with the handle spline of the other universal joint ball head through the spline sleeve and welded and reinforced, thereby connecting the two universal joints together through the spline pair. When the distance between the two universal joints changes, the spline shaft of the spline pair can slide and retract in the spline sleeve to adapt to the change in the length of the transmission shaft. The spline of the ball head handle is as follows: Figure 7 As shown, the splines of the corresponding spline shaft and spline sleeve are matched, and the figure takes a conventional involute spline as an example.

[0107] The spline mating pair of the present invention adopts a thin-wall structure and is integrally formed. On the one hand, it eliminates the original complex cutting process, which not only improves the processing quality of the parts but also saves a lot of processing costs. On the other hand, due to the significant reduction in weight, the spline mating pair can be processed by surface nitriding at a lower cost, which greatly improves the wear resistance of the parts and increases the product life.

[0108] The spline oil storage cylinder lubrication structure design of the present invention distributes the lubricating oil evenly on the inner surface of the spline part of the spline shaft, so that the lubricating oil can be more evenly and reliably distributed to the sliding surface of the spline mating pair through the oil distribution holes provided on the spline shaft under the action of the rotating centrifugal force, thereby improving the utilization efficiency and lubricating effect of the lubricating oil, and at the same time preventing the lubricating oil from agglomerating or deviating to one side to cause eccentricity and affect the dynamic balance of the transmission shaft.

[0109] like Figure 24 As shown, a dust cover 11 is also provided. One end of the dust cover 11 is fixedly connected to the sealing port T of the ball socket body, and the other end is connected to the spline sleeve 17.

[0110] The end of the dust cover 11 connected to the spline sleeve 17 is also provided with a vent 25 and a filter 18. The ball head is provided with an exhaust hole 16-1, one end of which is connected to the inner cavity 26 of the dust cover 11 and the other end is connected to the central chamber 21 of the spline fitting pair. The air in the central chamber 21 of the spline fitting pair can be connected to the inner cavity 26 of the dust cover 11 through the exhaust hole 16-1 provided on the ball head, and further connected to the filter 18 through the vent 25. Through the filter 18, breathing exchange is achieved with the external air to balance the pressure changes in the central chamber 21 of the spline fitting pair. The above is the breathing function of the spline fitting pair.

[0111] Figure 22 It is a three-dimensional schematic diagram of an arc-shaped spline shaft and a spline sleeve. The concave and convex shape of the spline surface is a curved surface composed of arc surfaces that are staggered and tangent to each other. The cross-section of the spline is a plum blossom shape, as shown in the figure. Figures 26-27 As shown; Figure 23 It is a three-dimensional schematic diagram of a rectangular spline shaft and a spline sleeve. The cross-sectional shape of the spline is a rectangular spline. Of course, there are many other forms of splines, such as trapezoidal splines, involute splines, triangular splines, etc., which are not listed here.

[0112] Furthermore, the sliding surface of the spline mating pair can be coated with nylon. After the spline shaft and / or spline sleeve are coated with nylon, the aforementioned spline oil reservoir lubrication method can be replaced by self-lubrication through nylon, thereby eliminating the need for spline oil reservoirs, oil distribution holes, and other structural arrangements.

[0113] Example 5:

[0114] This embodiment 5 is a variation of embodiment 4. Figure 25 As shown, it differs from Example 4 in that it also includes an oil storage plug 28, which seals one end of the spline oil storage cylinder 22. An oil storage chamber 23 is formed between the spline oil storage cylinder 22, the oil storage plug 28, and the spline shaft 16. The spline shaft 16 is provided with a plurality of oil distribution holes 16-2, which communicate with the oil storage chamber 23.

[0115] The present invention forms a closed oil storage chamber 23 between the spline oil storage cylinder 22, the oil storage plug 28 and the inner surface of the spline part of the spline shaft. At the same time, a plurality of oil distribution holes 16-2 are provided on the outer surface of the spline part of the spline shaft. The outer surface of the spline part of the spline shaft communicates with the oil storage chamber 23 through the oil distribution holes 16-2. The lubricating oil is stored in the oil storage chamber 23. The spline shaft 16 and the spline sleeve 17 are put together through the spline fitting to form a spline fitting pair. When the spline shaft 16 slides in the spline sleeve 17, the lubricating oil in the oil storage chamber 23 can reach the sliding fitting surface of the spline fitting pair through the oil distribution holes 16-2, thereby lubricating the spline fitting pair.

[0116] Preferably, a bell mouth 22-1 is provided at one end of the spline oil reservoir 22. When the spline oil reservoir 22 is coaxially nested within the inner cavity of the spline shaft 16, the bell mouth 22-1 blocks one end of the inner cavity of the spline portion of the spline shaft, while the other end of the spline oil reservoir 22 is connected to the oil storage plug 28, which also blocks the other end of the inner cavity of the spline portion of the spline shaft, thereby forming a closed oil storage chamber 23 between the spline oil reservoir, the oil storage plug, and the inner surface of the spline portion of the spline shaft.

[0117] like Figure 25 As shown, a spline dust cover 19 is also provided. One end of the spline dust cover 19 is fixedly connected to the spline shaft 16 , and the other end is connected to the spline sleeve 17 .

[0118] like Figure 29 As shown, the end of the spline dust cover 19 connected to the spline sleeve 17 is further provided with a vent 25 and a filter 18. The end of the spline shaft 16 away from the spline sleeve 17 is provided with an exhaust hole 16-1. One end of the exhaust hole 16-1 is connected to the inner cavity 20 of the spline dust cover 19, and the other end is connected to the central cavity 21 of the spline mating pair. The air in the central cavity 21 of the spline mating pair can be connected to the inner cavity 20 of the spline dust cover 19 through the exhaust hole 16-1 provided on the spline shaft 16, and further connected to the filter 18 through the vent 25. The air is exchanged with the outside air through the filter 18 to balance the pressure changes in the central cavity 21 of the spline mating pair. The above is the breathing function of the spline mating pair.

[0119] Example 6:

[0120] This embodiment 6 is another variation of embodiment 4, such as Figure 30-31 As shown, a lightweight spline mating pair includes a spline shaft 16 and a spline sleeve 17. The spline shaft 16 and the spline sleeve 17 are both thin-walled structures. The spline shaft 16 and the spline sleeve 17 are slidable spline mating pairs formed by involute spline mating. The spline shaft 16 and the spline sleeve 17 are involute splines. One end of the spline shaft 16 is provided with an internal spline, which is connected to the external spline (such as the external spline) provided on the ball head handle at one end of the transmission shaft. Figure 7 One end of the spline sleeve 17 slides with the outer spline of the spline shaft 16 through the internal spline, and the other end of the spline sleeve 17 slides with the outer spline of the ball head handle at the other end of the transmission shaft through the internal spline (as shown in FIG. Figure 7 The spline shaft 16, spline sleeve 17 and the ball shank of the transmission shaft are fixed by internal and external splines and then welded, which can improve the connection strength between the spline shaft 16, spline sleeve 17 and the ball shank of the transmission shaft.

[0121] Preferably, a dust cover 11 is further provided, one end of which is fixedly connected to the sealing port T of the ball socket body and the other end is connected to the spline sleeve 17. Alternatively, a spline dust cover 19 is further provided, one end of which is fixedly connected to the spline shaft 16 and the other end is connected to the spline sleeve 17.

[0122] Example 7:

[0123] like Figures 24-25 、 Figure 30 As shown, a lightweight transmission shaft includes a pair of lightweight universal joints and / or a pair of lightweight spline mating pairs, the lightweight universal joints are the lightweight universal joints described in any one of Examples 1-3, and / or the lightweight spline mating pairs are the lightweight spline mating pairs described in any one of Examples 4-6.

[0124] The lightweight drive shaft of the present invention has a ball socket and spline mating pair that both adopt a thin-wall structure and are integrally formed, realizing no-cutting or low-cutting processing, which not only greatly improves production efficiency and quality stability, but also greatly reduces part weight and processing costs, with a weight reduction of about 40-70%. It not only saves a large amount of steel and meets the lightweight development requirements of automotive parts, but also greatly improves product performance, the fitting accuracy of parts is higher, and the vibration and noise of the drive shaft are reduced.

[0125] Example 8:

[0126] The lightweight universal joint in Example 7 can be equivalently replaced by a cross-axis universal joint or a ball cage universal joint of traditional structure, which will not be repeated here.

[0127] Example 9:

[0128] The lightweight spline pair in Example 7 can be equivalently replaced by a spline shaft and spline sleeve of a traditional structure, such as Figure 32 As shown, it will not be repeated here. In this embodiment, the spline shaft 16 is integrally formed with the ball head 1, and the vent 16-1 is formed on the spline shaft 16. Because the spline shaft 16 and the ball head 1 are integrally formed, the shank of the ball head 1 is both a part of the ball head 1 and the spline shaft. Thus, the vent 16-1 provided on the ball head can also be described as the vent 16-1 provided on the spline shaft 16. Preferably, the end of the spline sleeve 17 away from the spline shaft 16 is connected to the other ball head 1 via a shaft tube.

[0129] In the description of this patent technology, it should also be noted that, unless otherwise clearly specified and limited, the terms "set," "install," "connect," "connect," and "fix" 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 an indirect connection through an intermediate medium, or it can be internal communication between two components. For ordinary technicians in this field, the specific meanings of the above terms in this patent technology can be understood according to specific circumstances.

[0130] Of course, the above content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of the embodiments of the present invention. The present invention is not limited to the above examples. Equal changes and improvements made by ordinary technicians in this field within the essential scope of the present invention should fall within the scope of the patent.

Claims

1. A lightweight universal joint, comprising a ball socket (3), a ball head (1), and a straight shaft (2), characterized in that: The ball socket (3) is a thin-walled structure and is no longer used to transmit transmission torque; the ball head (1) is rotatably mounted in the ball socket (3); a transmission hole is provided on the ball head (1); the straight shaft (2) passes through the transmission hole and passes through the center (R) of the ball head; both ends of the ball socket (3) are connected to fixed wings (8); the fixed wings (8) are provided with a bearing hole (8-1) and a transmission key (8-2); The ball socket (3) is an integral thin-walled integrally formed structure, and two plug holes (3-1) are symmetrically provided on the ball socket (3). The fixed wing (8) is provided with a plug interface (8-3), and the plug interface (8-3) is plugged into the plug hole (3-1). The straight shaft (2) is rotatably supported on the bearing hole (8-1) of the fixed wing (8).

2. A lightweight universal joint, comprising a ball socket (3), a ball head (1), and a straight shaft (2), characterized in that: The ball socket (3) is a thin-walled structure and is no longer used to transmit transmission torque; the ball head (1) is rotatably mounted in the ball socket (3); a transmission hole is provided on the ball head (1); the straight shaft (2) passes through the transmission hole and passes through the center (R) of the ball head; both ends of the ball socket (3) are connected to fixed wings (8); the fixed wings (8) are provided with a bearing hole (8-1) and a transmission key (8-2); The ball socket (3) is a split structure, comprising a ball socket I (31) and a ball socket II (32), wherein the ball socket I (31) and the ball socket II (32) are both thin-walled structures formed in one piece, and the ball socket I (31) and the ball socket II (32) are connected to each other and arranged symmetrically; The ball socket I (31) and the ball socket II (32) are both provided with an inner spherical surface (Q), a bearing hole (G) and a fixing cylinder (S); the fixing wing (8) is connected to the fixing cylinder (S) through the bearing hole (8-1); and the straight shaft (2) is rotatably supported on the bearing hole (G).

3. The lightweight universal joint according to claim 1, characterized in that: The ball socket (3) is an integrally-molded structure.

4. The lightweight universal joint according to claim 2, characterized in that: The ball socket I (31) and the ball socket II (32) are respectively provided with a sealing fixing surface (12), and the sealing fixing surface (12) is also provided with a sealing groove (14) and a sealing ring (15) placed thereon, for achieving a sealed connection between the ball socket I (31) and the ball socket II (32).

5. The lightweight universal joint according to claim 3 or 4, characterized in that: The invention also includes a rolling body (7), wherein the rolling body (7) is arranged at both ends of the straight shaft (2), and a raceway surface (1-1) is arranged at both ends of the transmission hole. The outer surface of the rolling body (7) cooperates with the raceway surface (1-1) of the transmission hole to transmit torque. The rolling body (7) can rotate around the axis of the straight shaft and can roll on the raceway surface (1-1) of the transmission hole.

6. The lightweight universal joint according to claim 5, characterized in that: The outer surface of the rolling body (7) is a conical surface (7-2), the conical surface (7-2) of the rolling body (7) cooperates with the raceway surface (1-1) of the transmission hole, the contact generatrix (M) of the two is a straight line, and the extension line of the contact generatrix (M) passes through the center (R) of the ball head (1).

7. The lightweight universal joint according to claim 6, characterized in that: It also includes a limiting mechanism, which is used to axially limit the rolling body (7).

8. The lightweight universal joint according to claim 7, characterized in that: It also includes an axial support mechanism for axially supporting and positioning the straight shaft.

9. The lightweight universal joint according to claim 8, characterized in that: The axial support mechanism is a steel ball (4) or a friction pad (P).

10. The lightweight universal joint according to any one of claims 1-4 or 6-8, characterized in that: The wall thickness of the ball socket is 0.2-5 mm.

11. The lightweight universal joint according to any one of claims 1 to 4 or 6 to 8, characterized in that: The diameter of the lip (K) of the socket is smaller than the ball diameter of the ball head.

12. A lightweight universal joint according to any one of claims 1-4 or 6-8, characterized in that: A positioning spherical surface (2-1) is provided at the middle portion of the straight shaft (2), a constraint surface (1-2) is provided at the middle portion of the transmission hole of the ball head (1), and the positioning spherical surface (2-1) is constrained and fitted within the constraint surface (1-2) of the transmission hole.

13. A lightweight transmission shaft comprising a universal joint and / or a splined pair, characterized in that: The universal joint is the lightweight universal joint according to any one of claims 1 to 12.

14. The lightweight transmission shaft according to claim 13, characterized in that: The spline fitting pair comprises a spline shaft (16) and a spline sleeve (17), both of which are thin-walled structures, and the spline shaft (16) and the spline sleeve (17) form a slidable spline fitting pair through spline fitting.

15. The lightweight transmission shaft according to claim 14, characterized in that: One end of the spline shaft (16) is provided with an internal spline, and the spline shaft (16) is fixedly connected to an external spline corresponding to the ball head handle at one end of the transmission shaft through the internal spline; an external spline is also provided on the outside of the spline shaft (16), and the external spline on the spline shaft (16) is slidably matched with the internal spline provided at one end of the spline sleeve (17), and the other end of the spline sleeve (17) is fixedly connected to an external spline corresponding to the ball head handle at the other end of the transmission shaft through its internal spline.

16. The lightweight transmission shaft according to claim 14, characterized in that: It also includes a spline oil storage cylinder (22), which is nested in the inner cavity of the spline shaft (16) to form an oil storage cavity (23). The spline shaft (16) is provided with a plurality of oil distribution holes (16-2), and the oil distribution holes (16-2) are in communication with the oil storage cavity (23).

17. The lightweight transmission shaft according to any one of claims 14 to 16, characterized in that: The inner splines and outer splines of the spline shaft and the spline sleeve are involute splines, rectangular splines or plum blossom splines.

18. The lightweight transmission shaft according to claim 17, characterized in that: A sealing port (T) is provided on the ball socket of the lightweight universal joint, a dust cover (11) is connected to the sealing port (T), one end of the dust cover (11) is connected to the sealing port (T), and the other end is connected to the handle of the ball head (1) or the spline sleeve of the transmission shaft.

19. The lightweight transmission shaft according to claim 18, characterized in that: The dust cover (11) is further provided with a filter (18) at one end connected to the spline sleeve (17) or the handle of the ball head. An exhaust hole (16-1) is provided on the ball head. The inner cavity (26) of the dust cover (11) is connected to the central cavity (21) of the spline mating pair through the exhaust hole (16-1). External air can enter the inner cavity (26) of the dust cover (11) after being filtered by the filter (18).

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