Universal joint cross shaft with reinforced structure

Abstract

The invention relates to the technical field of automobile chassis transmission shaft universal joints, in particular to a universal joint cross shaft of a reinforced structure. The universal joint cross shaft with the reinforced structure comprises a shaft body, a shaft head and reinforcing ribs. The four shaft heads are distributed in the circumferential direction of the shaft body. The projections of the four shaft heads in the axial direction of the shaft body are in a cross shape. The shaft head comprises a shaft neck, a first convex ring and a second convex ring; the plurality of reinforcing ribs are respectively arranged between the adjacent shaft heads; the reinforcing ribs are arranged around the axis of the shaft body in the length direction; the surface of the reinforcing rib comprises a first curved surface; the reference section passes through the axis of the shaft body; the reference cross section penetrates through part of the reinforcing ribs; in the reference section, a connecting line from the midpoint of the section line of the first curved surface to the geometric center point is a reference line; the included angle between the reference line and the axis of the shaft body is an acute angle. Therefore, the problem that the overall strength of the cross shaft is improved while the light weight of the cross shaft is guaranteed and the design tends to be equal in strength is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile chassis transmission shaft universal joints, in particular to a reinforced universal joint cross shaft. Background Art

[0002] Universal joints are key transmission components in automobiles, and their performance directly impacts a vehicle's power transmission efficiency, driving stability, and handling safety. In automotive powertrain systems, universal joints are primarily used to connect drive shafts with different axes, enabling variable-angle power transmission. For example, between the engine and drive axle, the relative position of the input and output shafts constantly changes due to factors such as frame deformation and suspension vibration. The universal joint's structural characteristics allow for stable torque transmission even when there is an angle between the two shafts, ensuring smooth transmission of power from the engine to the wheels. A cross-axle universal joint is a type of universal joint that includes a cross-axle, rolling elements, sealing rings, and end caps. The cross-axle typically consists of a shaft body and four shaft heads extending outward from the body in four directions. The cross-axle's structural design tends to be uniform in strength. The shaft head consists of a journal, a first raised ring, and a second raised ring. However, the processing technology of different parts of the cross shaft is different. For example, the shaft body is in a forged blank process structure state, the first convex ring near the shaft body is mostly in a lathe state, and the second convex ring and the shaft neck near the journal are in a grinding and finishing state, resulting in differences in the accuracy of the physical quality control of the cross shaft. In the static torsional strength destructive test, the fracture locations of the universal joint cross shaft are different. The journal neck, the gap between the two adjacent shaft heads on the shaft body, and the first convex ring and the second convex ring may all fail. The cross shaft structure design is currently tending to be lightweight. Therefore, when the processing technology of multiple parts of the cross shaft is different, how to improve the overall strength of the cross shaft while ensuring the lightweight of the cross shaft and the tendency towards equal strength design has become a technical problem that needs to be solved urgently. Summary of the Invention

[0003] In order to solve the problem of improving the overall strength of the cross shaft while ensuring the lightweight and uniform strength design of the cross shaft, the present invention provides a reinforced universal joint cross shaft, comprising:

[0004] A shaft body, wherein the midpoint of the shaft body in its own axial direction is the geometric center point; and the surface of the shaft body is the forging blank surface;

[0005] A shaft head, wherein four shaft heads are distributed along the circumference of the shaft body; the axis of the shaft head is perpendicular to the axis of the shaft body; the projections of the four shaft heads along the axial direction of the shaft body are cross-shaped; the shaft head and the shaft body are integrally formed; the shaft head comprises a shaft neck, a first convex ring and a second convex ring; the shaft neck, the first convex ring and the second convex ring are coaxially arranged; the diameter of the shaft neck is smaller than the diameter of the first convex ring; the diameter of the first convex ring is smaller than the diameter of the second convex ring; the first convex ring and the second convex ring are located at the end of the shaft neck close to the shaft body; the second convex ring is located on the side of the first convex ring close to the shaft body; the surfaces of the shaft neck and the first convex ring are both ground and finished surfaces; the surface of the second convex ring is a lathe-machined surface;

[0006] Reinforcing ribs, wherein a plurality of the reinforcing ribs are provided; the plurality of the reinforcing ribs are distributed between adjacent shaft heads; the length direction of the reinforcing ribs is arranged around the axis of the shaft body; the surface of the reinforcing ribs includes a first curved surface; the reference section passes through the axis of the shaft body; the reference section passes through part of the reinforcing ribs; in the reference section, the line connecting the midpoint of the section line of the first curved surface to the geometric center point is the reference line; the angle between the reference line and the axis of the shaft body is an acute angle.

[0007] In some embodiments, the axis of the shaft body is perpendicular to the central plane, and the geometric center point is located in the central plane; in the reference section, the center of the section line of the first curved surface is located on the side of the reference line close to the central plane.

[0008] In some embodiments, the angle between the reference line and the central plane is between 24° and 30°.

[0009] In some embodiments, the surface of the reinforcing rib also includes a first plane and a second plane; the first curved surface is located between the first plane and the second plane; the first plane is located on the side of the first curved surface away from the center plane; in the reference section, the length of the cross-sectional line of the first plane is less than the length of the cross-sectional line of the second plane.

[0010] In some embodiments, the surface of the reinforcing rib further includes two transition curved surfaces; one of the transition curved surfaces is located between the first plane and the surface of the shaft body, and the other transition curved surface is located between the second plane and the surface of the shaft body.

[0011] In some embodiments, the angle between the first plane and the central plane is 4° to 10°.

[0012] In some embodiments, the angle between the second plane and the axis of the shaft body is between 11° and 17°.

[0013] In some embodiments, the height of the reinforcing rib protruding from the surface of the shaft body is 1 mm to 2 mm.

[0014] In some embodiments, four of the reinforcing ribs form a group; each group of the reinforcing ribs is concentrically arranged; and there are two groups of the reinforcing ribs arrayed along the axial direction of the shaft body.

[0015] In some embodiments, the reinforced universal joint cross shaft further includes a bearing; four bearings are provided; the bearings are arranged in a one-to-one correspondence with the shaft heads; and the bearings are sleeved on the shaft neck.

[0016] In order to solve the problem of improving the overall strength of the cross shaft while ensuring lightweight and uniform strength design, the present invention has the following advantages:

[0017] By providing multiple reinforcing ribs between adjacent shaft heads, the weak area of ​​stress concentration at the connection between the shaft head and the shaft body can be precisely reinforced, reducing the local high stress caused by the sudden change in the root force when the shaft head is subjected to stress. At the same time, the reinforcing ribs are arranged around the axis of the shaft body in the length direction, forming an annular reinforcement structure evenly distributed along the circumference, which can evenly transfer the torque and stress borne by the cross shaft to the shaft body, avoiding excessive local structural loads. The first curved surface of the reinforcing rib surface is at an acute angle to the axis of the shaft body in the reference section, which makes the length of the reinforcing rib set on the shaft body longer, rather than setting it to the shortest length in the middle of the adjacent shaft heads. In a complex stress scenario, the stress is dispersed to a larger range on the shaft body in the inclined direction, avoiding stress concentration caused by sudden changes in structural dimensions. In addition, the synergistic effect of the "multi-point support" of multiple reinforcing ribs significantly improves the overall stiffness of the connection between the shaft body and the shaft head, thereby improving the overall strength and service life of the cross shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of a reinforced universal joint cross shaft structure according to an embodiment is shown;

[0019] Figure 2 Shown Figure 1 AA sectional view of the reinforced universal joint cross shaft;

[0020] Figure 3 Shown Figure 2 A schematic diagram of the structure of the cross-sectional area in FIG.

[0021] Figure 4 Shown Figure 2 A local enlarged schematic diagram of point B in FIG.

[0022] Figure 5 A schematic diagram of the reinforced universal joint cross shaft structure of another embodiment is shown.

[0023] Figure numerals: 10 shaft body; 20 shaft head; 21 shaft neck; 22 first convex ring; 23 second convex ring; 30 reinforcing rib; 31 first curved surface; 32 first plane; 33 second plane; 34 transition curved surface; 40 reference line; 50 center plane; 60 bearing. DETAILED DESCRIPTION

[0024] The present disclosure will now be discussed with reference to several exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the present disclosure, rather than to imply any limitation on the scope of the present disclosure.

[0025] As used herein, the term "including" and its variations are to be interpreted as open-ended terms meaning "including, but not limited to." The term "based on" is to be interpreted as "based, at least in part, on." The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment." The term "another embodiment" is to be interpreted as "at least one other embodiment." Terms such as "upper," "lower," "left," "right," "front," "back," "top," "bottom," "inner," "outer," "vertical," "horizontal," "transverse," and "longitudinal" indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. These terms are primarily intended to better describe the present application and its embodiments and are not intended to limit the devices, elements, or components indicated to having a specific orientation, or to being constructed and operated in a specific orientation. Furthermore, some of the above terms may be used to indicate other meanings besides orientation or positional relationships. For example, the term "on" may, in certain circumstances, be used to indicate a dependency or connection relationship. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances. Furthermore, the terms "installed," "disposed," "provided with," "connected," and "connected" are to be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances. In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements, or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise specified, "plurality" means two or more.

[0026] Example 1:

[0027] The universal joint is one of the key transmission components of an automobile, and its performance directly affects the vehicle's power transmission efficiency, driving stability, and handling safety. A cross-axis universal joint is a type of universal joint, which includes a cross-axis, rolling elements, sealing rings, and end covers. The cross-axis usually includes an axis body 10 and four axis heads 20 extending outward from the axis body 10 in four directions. At present, the structural design of the cross-axis tends to be equal strength and lightweight. In order to solve the problem of improving the overall strength of the cross-axis while ensuring the lightweight and equal strength design of the cross-axis, this embodiment discloses a reinforced structural universal joint cross-axis.

[0028] In this embodiment, if Figure 1 As shown, the reinforced universal joint cross shaft is composed of a shaft body 10 , a shaft head 20 and a reinforcement rib 30 .

[0029] The shaft body 10, the midpoint of the shaft body 10 in its own axial direction is the geometric center point. The surface of the shaft body 10 is a forged blank surface, which reduces the processing cost while ensuring the strength of the shaft body 10. The shaft head 20, there are four shaft heads 20 distributed along the circumference of the shaft body 10, the axis of the shaft head 20 is perpendicular to the axis of the shaft body 10, and the projections of the four shaft heads 20 along the axial direction of the shaft body 10 are cross-shaped. The four shaft heads 20 are evenly divided into two groups. The two shaft heads 20 in the same group are located on the same axis. The two groups of shaft heads 20 respectively cooperate with the two external universal joint forks to form the core transmission unit in the automobile chassis, realizing the variable angle power transmission function of the cross-axis universal joint.

[0030] The shaft head 20 is integrally formed with the shaft body 10, eliminating the extra weight and stress concentration associated with welding and other connection methods, thereby enhancing the overall strength of the cross shaft. The shaft head 20 comprises a journal 21, a first raised ring 22, and a second raised ring 23. These three components are coaxially arranged. The diameter of the journal 21 is smaller than that of the first raised ring 22, which in turn is smaller than that of the second raised ring 23. This results in the diameters of the journal 21, first raised ring 22, and second raised ring 23 increasing in sequence. The first and second raised rings 22 and 23 are located at the end of the journal 21 closest to the shaft body 10, while the second raised ring 23 is located on the side of the first raised ring 22 closer to the shaft body 10. This results in the journal 21, first raised ring 22, and second raised ring 23 gradually increasing in diameter as they move from the journal 21 toward the shaft body 10. Furthermore, because the shaft head 20 is integrally formed with the shaft body 10 and made of the same material, the upper limits of stress and torque that these three components can withstand increase in sequence. By arranging the first convex ring 22 and the second convex ring 23 in this way, the torque applied to the journal 21 can be transferred to the shaft body 10, thereby reducing the sudden change in the maximum torque applied to both the journal 21 and the shaft body 10 and improving the overall strength of the cross shaft.

[0031] Multiple reinforcing ribs 30 are provided. These ribs 30 are distributed between adjacent shaft heads 20. During cross-shaft rotation, adjacent shaft heads 20 are subject to stress and torque transmitted by the external universal joint yoke. This arrangement allows the area of ​​the shaft body 10 between adjacent shaft heads 20 to withstand greater stress, thereby increasing the strength of the weak area at the connection between the shaft head 20 and the shaft body 10, where stress is concentrated, and reducing localized high stress caused by sudden changes in force at the base of the shaft head 20 when the shaft head 20 is subjected to stress.

[0032] The surface of the shaft body 10 is a forged blank, the surfaces of the journal 21 and the first raised ring 22 are ground and finished, and the surface of the second raised ring 23 is a lathe-machined surface. Because the machining processes for the four aforementioned parts are not identical, and given the same material dimensions, materials with lower machining precision generally have lower strength, in order to achieve equal strength design, the diameter of the parts with lower machining precision needs to be larger. This is one of the reasons why the diameters of the journal 21, first raised ring 22, and second raised ring 23 are set to increase in sequence. Therefore, compared to increasing the overall thickness of the shaft body 10 and the shaft head 20 to improve strength, adding reinforcing ribs 30 only in the key stress-bearing areas can improve strength without significantly increasing the overall size and weight of the cross shaft, which is in line with the trend of lightweight design.

[0033] The length direction of the reinforcing ribs 30 is arranged around the axis of the shaft body 10, corresponding to the circumferential distribution of the shaft head 20 along the shaft body 10, forming an annular reinforcement structure evenly distributed along the circumferential direction, which can evenly transfer the torque and stress borne by the shaft head 20 to the shaft body 10, avoiding excessive local structural loads and improving the overall strength of the cross shaft.

[0034] like Figure 4 As shown, the surface of the reinforcing rib 30 includes a first curved surface 31. The reference section passes through the axis of the shaft body 10 and partially penetrates the reinforcing rib 30. In the reference section, the line connecting the midpoint of the cross section of the first curved surface 31 to the geometric center point is the reference line 40. The angle between the reference line 40 and the axis of the shaft body 10 is acute. If the reinforcing rib 30 is installed at the shortest point between adjacent shaft heads 20 on the shaft body 10, the angle between the reference line 40 and the axis of the shaft body 10 is a right angle. The length of this section of the reinforcing rib 30 is relatively short, and the degree of strength improvement is limited. Moreover, the degree of strength improvement provided by this section of the reinforcing rib 30 at the opening position between adjacent shaft heads 20 on the shaft body 10 is significantly greater than the degree of strength improvement provided by the reinforcing rib 30 at the journal 21, the first raised ring 22, the second raised ring 23, and the areas of the shaft body 10 away from the opening position, which is not conducive to the equal strength design of the reinforced universal joint cross.

[0035] The present invention sets the angle between the reference line 40 and the axis of the shaft body 10 to be an acute angle, which can extend the length of the reinforcing rib 30 on the shaft body 10, so that in a complex force scenario, the reinforcing rib 30 can disperse the stress to a larger range on the shaft body 10 along the inclined direction, and can improve the strength of the journal 21, the first convex ring 22, the second convex ring 23 and the opening position between adjacent shaft heads 20 on the shaft body 10 to a similar extent, minimize the quality difference of the journal 21, the first convex ring 22, the second convex ring 23 and the opening position, improve the overall strength of the cross shaft while ensuring that all parts tend to be of equal strength.

[0036] Furthermore, if Figure 2 As shown, the axis of the shaft body 10 is perpendicular to the center plane 50, and the geometric center point is located in the center plane 50. In the reference cross section, the center point of the cross-section line of the first curved surface 31 is located on the side of the reference line 40 close to the center plane 50, and the reference line 40 passes through the midpoint of the cross-section line of the first curved surface 31 and the geometric center point. This makes the average height of the side of the reinforcing rib 30 close to the center plane 50 protruding from the surface of the shaft body 10 higher. Because the reinforcing rib 30 is located between adjacent shaft heads 20, it can further enhance the strength of the journal 21, the first convex ring 22, the second convex ring 23 and the opening position between the adjacent shaft heads 20 on the shaft body 10. This improves the overall strength of the cross shaft while ensuring that each part tends to be of equal strength.

[0037] Furthermore, if Figure 3 As shown, the included angle α1 between the reference line 40 and the center plane 50 is within the range of 24° to 30°. Finite element static strength analysis of the cross-shaft in this embodiment shows that when α1 is set within the range of 24° to 30°, the maximum equivalent stress of the cross-shaft decreases more significantly when loaded with the same torque than when it is set within other acute angle ranges, thereby significantly improving the overall strength of the cross-shaft.

[0038] Preferably, α1 can be set to 27.4°. Under the premise of loading the same torque, the maximum equivalent stress of the cross shaft decreases the most and the overall strength of the cross shaft increases the most.

[0039] Furthermore, if Figure 4 As shown, the surface of the reinforcing rib 30 further includes a first plane 32 and a second plane 33. The first curved surface 31 is located between the first plane 32 and the second plane 33, and the first plane 32 is located on the side of the first curved surface 31 away from the center plane 50. Figure 4As shown, in the reference cross section, the length of the cross-section of the first plane 32 is shorter than the length of the cross-section of the second plane 33. The cross-sections of the first and second planes 32 and 33 are marked in red. This arrangement further increases the width of the reinforcing ribs 30 toward the gap between adjacent shaft bodies, ultimately improving the overall strength of the cross-axle while ensuring that all parts are of equal strength.

[0040] Furthermore, if Figure 4 As shown, the surface of the reinforcing rib 30 also includes two transition curved surfaces 34. One transition curved surface 34 is located between the first plane 32 and the surface of the shaft body 10, and the other transition curved surface 34 is located between the second plane 33 and the surface of the shaft body 10. This arrangement ensures a smooth transition between the first plane 32, the second plane 33, and the shaft body 10, avoiding stress concentration areas and reducing processing difficulty.

[0041] Furthermore, if Figure 3 and Figure 4 As shown, the included angle β1 between the first plane 32 and the center plane 50 is between 4° and 10°. Finite element static strength analysis of the cross-shaft in this embodiment shows that when β1 is set within the range of 4° to 10°, the maximum equivalent stress of the cross-shaft decreases more significantly when loaded with the same torque than when set within other angle ranges, thereby significantly improving the overall strength of the cross-shaft.

[0042] Preferably, β1 can be set to 5°. Under the premise of loading the same torque, the maximum equivalent stress of the cross shaft decreases the most and the overall strength of the cross shaft increases the most.

[0043] Furthermore, if Figure 3 and Figure 4 As shown, the included angle β2 between the second plane 33 and the axis of the shaft body 10 is between 11° and 17°. Finite element static strength analysis of the cross-shaft in this embodiment shows that when β2 is set within the range of 11° to 17°, the maximum equivalent stress of the cross-shaft decreases more significantly when loaded with the same torque than when set within other angle ranges, thereby further improving the overall strength of the cross-shaft.

[0044] Preferably, β2 can be set to 14°. Under the premise of loading the same torque, the maximum equivalent stress of the cross shaft decreases the most and the overall strength of the cross shaft increases the most.

[0045] In other embodiments, β2 may be set to twice β1 to improve the overall strength of the cross shaft.

[0046] Furthermore, if Figure 1 and Figure 4As shown, the height L1 of the reinforcing rib 30 protruding from the surface of the shaft body 10 is 1mm to 2mm. Finite element static strength analysis of the cross-shaft in this embodiment shows that when L1 is set within the range of 1mm to 2mm, the maximum equivalent stress of the cross-shaft decreases more significantly under the same torque loading than when it is set at other height ranges, thereby significantly improving the overall strength of the cross-shaft. This configuration also minimizes the weight change of the cross-shaft, meeting the requirements of lightweight design.

[0047] Preferably, L1 can be set to 1.25 mm. Under the premise of loading the same torque, the maximum equivalent stress of the cross shaft decreases the most and the overall strength of the cross shaft increases the most.

[0048] Furthermore, if Figure 1 As shown, four reinforcing ribs 30 form a group. Each group of reinforcing ribs 30 is concentrically arranged, corresponding to the length of the ribs 30 surrounding the axis of the shaft body 10. Two groups of reinforcing ribs 30 are arranged along the axis of the shaft body 10. These two groups of reinforcing ribs 30 can be symmetrically arranged on either side of the center plane. This ensures a more comprehensive and stable strength-enhancing effect of the reinforcing ribs 30, effectively preventing stress transfer and improving the overall strength of the cross-axle while ensuring a uniform strength design.

[0049] Furthermore, if Figure 5 As shown, the reinforced universal joint cross also includes bearings 60. Four bearings 60 are provided, one corresponding to each shaft head 20. Bearings 60 are sleeved onto the shaft journal 21. The surface of the shaft head 20 mates with the inner ring of the bearing 60, while the outer ring of the bearing 60 mates with the external universal joint fork shaft hole, achieving low-friction rotation. The first and second raised rings 22, 23 limit axial displacement of the bearings 60, preventing looseness and ensuring stable torque transmission.

[0050] Furthermore, the bearing 60 can be configured as a needle roller bearing 60. The needle roller bearing 60 has a smaller radial cross-section, providing reliable support at the radially confined cross-shaft journal 21. Furthermore, compared to other bearings 60 with the same load capacity, the needle roller bearing 60 has slender needles, a simplified structure, and uses less material, resulting in a lighter overall weight, meeting the requirements of lightweight design.

[0051] Finite element static strength analysis was performed on the cross-shaft before and after the modification in this embodiment. The pre-modification state was without ribs, while the post-modification state was with ribs. The rib parameters were set to: α1 at 27.4°, β1 at 5°, β2 at 14°, and L1 at 1.25mm. Under the same torque, the maximum equivalent stress of the cross-shaft before the modification was 813 MPa, while the maximum equivalent stress after the modification was 791 MPa, a 2.7% decrease. The maximum equivalent stress values ​​for the shaft body 10, first raised ring 22, second raised ring 23, journal 21, and the cross-shaft as a whole are shown in the table below. The maximum equivalent stress values ​​for each component decreased to varying degrees, correspondingly improving the strength of each component, thereby enhancing the overall strength of the cross-shaft. The strength increase was particularly significant at the first raised ring 22 and journal 21. This allows for structural control of the fracture location of the universal joint cross-shaft during the static torsional strength destructive test, thereby facilitating control of the overall strength and structural design of the universal joint cross-shaft.

[0052] The following table is a comparison of the maximum equivalent stress data of the finite element static strength analysis before and after the cross shaft improvement:

[0053]

[0054] The experimental results show that while the strength of the cross shaft is improved after the improvement, the weight of the cross shaft is 3.3179 kg before the improvement and 3.3225 kg after the improvement, with a weight change of 0.14%. This has little impact on the weight of the parts and meets the requirements of lightweight design.

[0055] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present disclosure, and that in actual applications, various changes may be made thereto in form and detail without departing from the scope of the present disclosure.

Claims

1. A reinforced universal joint cross shaft, characterized in that: The reinforced universal joint cross shaft comprises: A shaft body, wherein the midpoint of the shaft body in its own axial direction is the geometric center point; and the surface of the shaft body is the forging blank surface; A shaft head, wherein four shaft heads are distributed along the circumference of the shaft body; the axis of the shaft head is perpendicular to the axis of the shaft body; the projections of the four shaft heads along the axial direction of the shaft body are cross-shaped; the shaft head and the shaft body are integrally formed; the shaft head comprises a shaft neck, a first convex ring and a second convex ring; the shaft neck, the first convex ring and the second convex ring are coaxially arranged; the diameter of the shaft neck is smaller than the diameter of the first convex ring; the diameter of the first convex ring is smaller than the diameter of the second convex ring; the first convex ring and the second convex ring are located at the end of the shaft neck close to the shaft body; the second convex ring is located on the side of the first convex ring close to the shaft body; the surfaces of the shaft neck and the first convex ring are both ground and finished surfaces; the surface of the second convex ring is a lathe-machined surface; Reinforcing ribs, wherein a plurality of the reinforcing ribs are provided; the plurality of the reinforcing ribs are distributed between adjacent shaft heads; the length direction of the reinforcing ribs is arranged around the axis of the shaft body; the surface of the reinforcing ribs includes a first curved surface; the reference section passes through the axis of the shaft body; the reference section passes through part of the reinforcing ribs; in the reference section, the line connecting the midpoint of the section line of the first curved surface to the geometric center point is the reference line; the angle between the reference line and the axis of the shaft body is an acute angle.

2. The reinforced universal joint cross shaft according to claim 1, characterized in that: The axis of the shaft body is perpendicular to the central plane, and the geometric center point is located in the central plane; in the reference cross section, the center of the cross-sectional line of the first curved surface is located on the side of the reference line close to the central plane.

3. The reinforced universal joint cross shaft according to claim 2, characterized in that: The angle between the reference line and the central plane is between 24° and 30°.

4. The reinforced universal joint cross shaft according to claim 2, characterized in that: The surface of the reinforcing rib also includes a first plane and a second plane; the first curved surface is located between the first plane and the second plane; the first plane is located on the side of the first curved surface away from the center plane; in the reference section, the length of the cross-sectional line of the first plane is less than the length of the cross-sectional line of the second plane.

5. The reinforced universal joint cross shaft according to claim 4, characterized in that: The surface of the reinforcing rib further includes two transition curved surfaces; one of the transition curved surfaces is located between the first plane and the surface of the shaft body, and the other transition curved surface is located between the second plane and the surface of the shaft body.

6. The reinforced universal joint cross shaft according to claim 4, characterized in that: The angle between the first plane and the central plane is 4° to 10°.

7. The reinforced universal joint cross shaft according to claim 4, characterized in that: The included angle between the second plane and the axis of the shaft body is 11° to 17°.

8. The reinforced universal joint cross shaft according to claim 1, characterized in that: The height of the reinforcing rib protruding from the surface of the shaft body is 1mm~2mm.

9. The reinforced universal joint cross shaft according to claim 1, characterized in that: Four reinforcing ribs form a group; each group of reinforcing ribs is concentrically arranged; and there are two groups of reinforcing ribs arrayed along the axial direction of the shaft body.

10. The reinforced universal joint cross shaft according to claim 1, characterized in that: The reinforced universal joint cross shaft further includes a bearing; four bearings are provided; the bearings are arranged in a one-to-one correspondence with the shaft heads; and the bearings are sleeved on the shaft neck.

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