Sliding structure of vehicle steering intermediate shaft and preparation method therefor

Abstract

A sliding structure of a vehicle steering intermediate shaft and a preparation method therefor, which belong to the technical field of vehicle steering systems. The sliding structure is characterized by comprising an outer tube and a sliding shaft arranged in the outer tube, wherein the outer tube is formed by integrally molding or fixedly connecting a connecting tube and a sliding tube; an outer circular face of the sliding shaft is provided with an outer sliding structure, an inner wall of the sliding tube is provided with an inner sliding structure, and the sliding shaft and the outer tube are in meshing transmission connection by means of the outer sliding structure and the inner sliding structure; and a friction coating is provided on the surface of the outer sliding structure, a shaft sleeve is provided on part or all of the surface of the inner sliding structure, and the shaft sleeve and the friction coating form a sliding friction pair. The present invention can significantly reduce frictional force, has a small sliding force, small angular backlash, high motion precision and high wear resistance, meets the requirements of long service life, and can be widely applied in various vehicle steering systems, thereby improving the steering flexibility and stability.

Description

Vehicle steering intermediate shaft sliding structure and preparation method thereof TECHNICAL FIELD

[0001] The present application relates to a vehicle steering intermediate shaft sliding structure and a preparation method thereof, and belongs to the technical field of vehicle steering systems. BACKGROUND

[0002] In a vehicle steering system, a steering intermediate shaft is a transmission component for connecting a steering column and a steering gear, so as to transmit torque and rotation angle, and is usually composed of a universal joint yoke and a sliding pair connecting the universal joint yokes. At present, the commonly used sliding pairs of the steering intermediate shaft include hexagonal spline, involute spline and ball spline sliding structures, but the above sliding structures all have different degrees of defects.

[0003] The hexagonal spline sliding structure has the defects of large angular play, unsmooth sliding and poor wear resistance; the involute spline sliding structure has the defects of large sliding force and poor wear resistance; and the ball spline sliding structure has a very high cost and no market competitiveness.

[0004] The above traditional sliding structures often have problems of unsmooth sliding, low service life or high cost due to unreasonable design or improper material selection. Therefore, developing a new type of sliding structure and a preparation method thereof to improve the performance and durability of the vehicle steering system has become a problem to be solved in the current vehicle industry.

[0005] SUMMARY

[0006] The technical purpose of the present application is to provide a vehicle steering intermediate shaft sliding structure and a preparation method thereof, which have the advantages of simple structure, smooth sliding, wear resistance and low cost, in view of the shortcomings of the prior art.

[0007] The first purpose of the present application is to provide a vehicle steering intermediate shaft sliding structure, characterized in that it comprises an outer tube and a sliding shaft arranged in the outer tube, the outer tube is integrally formed or fixedly connected by a connecting tube and a sliding tube; an outer sliding structure is arranged on the outer surface of the sliding shaft, an inner sliding structure is arranged on the inner wall of the sliding tube, the sliding shaft and the outer tube are connected in transmission through the engagement of the outer sliding structure and the inner sliding structure; a friction coating is arranged on the surface of the outer sliding structure, and a shaft sleeve is arranged on part or all of the surface of the inner sliding structure, the shaft sleeve and the friction coating forming a pair of sliding friction pairs.

[0008] The combination of the sliding shaft, the sliding pipe and the shaft sleeve is the core component of the sliding structure. The outer sliding structure is arranged on the outer surface of the sliding shaft along the axial direction, and the sliding movement of the intermediate shaft is appropriate. The surface of the outer sliding structure is treated by special surface treatment, such as adding a friction coating to reduce the friction coefficient and wear resistance. The sliding pipe is made of a good wear-resistant precision drawn pipe or a precision machined steel pipe, and the inner sliding structure can be selected in various forms such as spline structure, multi-tooth structure, clover or key structure according to actual needs. The combination of the sliding shaft with the friction coating and the sliding pipe with the shaft sleeve ensures low sliding force and high service life.

[0009] Further, the shaft sleeve is made of a three-layer composite material plate, and the three-layer composite material plate is composed of a steel plate layer (base material), a copper powder layer (intermediate layer) and a PTFE composite formula layer (outer layer, friction working surface) from bottom to top.

[0010] In the above scheme, the shaft sleeve is an important component in the sliding structure, and its main function is to reduce the friction and wear between the sliding shaft and the sliding pipe. The shaft sleeve is made of special materials, and the combination of the steel plate (which can be plated with copper on the surface of the steel plate to improve the durability and strength), the sintered copper powder layer and the PTFE composite formula layer has good self-lubricating property and wear resistance.

[0011] Further, the material components of the PTFE composite formula layer include PTFE powder, reinforcing fibers, thermoplastic polyfluoroethylene propylene and nano-aluminum oxide; the thermoplastic polyfluoroethylene propylene after heating can infiltrate the surface of each material, so that the composite material forms an organic whole, thereby improving the bonding force between each material and the mechanical properties of the whole composite material.

[0012] Further, the friction coating on the surface of the outer sliding structure is a friction-reducing material coating, or a wear-resistant material coating, or a mixed coating of friction-reducing material and wear-resistant material. The mixed coating can be formed by first electroplating a metal layer (preferably chromium plating) on the surface of the outer sliding structure to form a wear-resistant layer and increase the wear resistance, and then spraying a friction-reducing material coating.

[0013] Further, the friction-reducing material coating can be made of molybdenum disulfide or PTFE composite spraying material, and the PTFE composite spraying material is composed of PTFE, N-methyl-2-pyrrolidone, 1,2,4-trimethylbenzene, methyl isobutyl ketone and carbon black.

[0014] Further, the inner sliding structure includes a plurality of circular arc grooves uniformly distributed in the circumferential direction; the shaft sleeve is a circular arc sleeve matched with the circular arc grooves and is fixedly attached to the corresponding circular arc grooves; the outer sliding structure is a plurality of circular arc protrusions uniformly distributed in the circumferential direction to engage and transmit with the circular arc grooves with the shaft sleeve; the number of circular arc grooves, circular arc protrusions and circular arc sleeves is consistent and corresponds one-to-one.

[0015] Further, the shaft sleeve is fitted with the corresponding circular arc groove and has consistent curvature, and the meshing contact area of the circular arc protrusion and the corresponding shaft sleeve can be adjusted in size as needed to ensure that the torque and rotation angle are completed; for example, for the working condition of transmitting large torque and requiring low sliding force, the inner and outer sliding structures with larger meshing contact area can be selected; for the working condition of not requiring high torque and requiring strict sliding force, the inner and outer sliding structures with slightly smaller meshing contact area can be selected. Specifically,

[0016] The groove bottom profile line (in the circumferential direction) of each circular arc groove is composed of a single curvature circular arc line or smoothly connected by a plurality of circular arc lines with varying curvatures; the outer profile line of each circular arc protrusion has local or overall consistent curvature with the curvature of the groove bottom profile line of the corresponding circular arc groove.

[0017] Further, a small protruding boss is arranged between the two adjacent circular arc grooves to prevent the shaft sleeve from sliding in the circumferential direction after installation.

[0018] Further, the outer side end of the inner wall of the sliding pipe is provided with a protruding pressing rib, and the connecting pipe is provided with a limiting step at the contact position with the sliding pipe to limit the shaft sleeve from axially sliding from both ends of the shaft sleeve. The end face of the sliding shaft can also be prevented from axially moving by using a retaining ring or a circlip.

[0019] Further, the sliding structure of the present application can be arranged at any position of the intermediate shaft as needed and is suitable for application scenarios with long sliding distance. In order to reduce the cantilever effect, a lubricating body is arranged on the outer side wall of the sliding shaft away from the outer sliding structure. The lubricating body can be annular and is installed in the annular groove on the outer side wall of the sliding shaft. The lubricating body is gap-fitted with the inner wall of the connecting pipe and forms another sliding friction pair with the connecting pipe.

[0020] The above scheme can effectively reduce the cantilever effect and improve the flexibility and stability of the steering system. At the same time, the arrangement of the lubricating body can further reduce the friction coefficient and reduce wear and energy consumption. The annular lubricating body is at least one and is sintered after being pressure-cast in a mold using PTFE powder.

[0021] Further, in order to prevent foreign matter from entering the sliding working area, a double-sealing design is adopted.

[0022] An inner dust cover is arranged at the inner cavity of the sliding pipe and the outer side end of the sliding shaft to prevent foreign matter from entering the friction pair, and the inner dust cover is made of a low-friction coefficient material to maintain low friction force while sealing; a corrugated outer dust cover (connected with the external assembly) is further arranged at the outer side end of the sliding pipe to ensure full sealing within the sliding range. The double-sealing structure can effectively prevent dust, water and other impurities from entering the sliding friction pair, thereby ensuring the stability and durability of the sliding structure.

[0023] The second object of the present application is to provide a preparation method of the vehicle steering intermediate shaft slip structure, comprising:

[0024] (1) Preparation of the slip pipe

[0025] The slip pipe is prepared by using pipe material for broaching, and the inner surface is broached into a predetermined inner sliding structure shape, the inner sliding structure is a plurality of circular arc grooves uniformly distributed in the circumferential direction, and a small boss is arranged between adjacent two circular arc grooves to prevent the shaft sleeve from slipping in the circumferential direction; the slip pipe is connected with the connecting pipe to form an integrated body (which can also be integrally formed), forming an outer pipe to ensure that the connecting pipe and the slip pipe are connected tightly;

[0026] (2) Preparation of the slip shaft

[0027] ① Drawing forming is adopted to form an outer sliding structure on the outer cylindrical surface of the slip shaft, the outer sliding structure is a circular arc protrusion for meshing transmission with the circular arc groove; for occasions with strict requirements on slip force and angular play, the outer sliding structure can be ground after drawing forming; the surface of the slip shaft is plated with a metal layer as needed;

[0028] ② The surface of the slip shaft is cleaned, degreased and preheated, and the drying temperature is 110-130°C;

[0029] ③ The PTFE composite spraying material after stirring is loaded into a spray gun, and the outer sliding structure surface of the slip shaft is uniformly sprayed to form a friction coating, and the thickness of the friction coating is 0.005-0.015mm;

[0030] ④ The sprayed slip shaft is dried at 170-190°C for 2h to enhance the bonding force;

[0031] (3) Preparation of the shaft sleeve

[0032] ① A layer of copper powder is laid on a steel plate and sintered and heat preserved to obtain a copper powder plate;

[0033] The steel plate is copper plated as needed, and the thickness is 0.3-2.5mm; the copper powder is 100-400 mesh, and the laying thickness is 0.20-0.30mm, the sintering temperature is 880-910°C, and the heat preservation time is 30min;

[0034] ② A mud-like PTFE composite formula material is laid on the surface of the copper powder plate and plasticized and heat preserved to obtain a three-layer composite material plate; the laying thickness of the mud-like PTFE composite formula material is 0.01-0.10mm, the plasticizing temperature is 365-385°C, and the heat preservation time is 50min;

[0035] ③ using the finishing mill to roll the three-layer composite material plate, the composite material is rolled into the copper powder aperture, and the aperture of the composite material layer is removed, the compactness of the composite material is increased, and the finished three-layer composite material plate with a thickness of 0.48-2.48 mm is obtained;

[0036] ④ the finished three-layer composite material plate is cut into small plate materials (such as: the length and width size is selected to be 21.1mm*70mm) meeting the size requirements;

[0037] ⑤ the small plate materials are bent into bearing shell shape through a forming die, and the bending curvature and angle meet the product requirements;

[0038] ⑥ the small plate materials are shaped using a shaping mandrel to form the finished bearing sleeve with a circular arc shape;

[0039] (4) Assemble the sliding structure

[0040] ① the prepared circular arc finished bearing sleeve is assembled into the circular arc groove of the sliding pipe, so that the curvature of the bearing sleeve is consistent with the curvature of the corresponding circular arc groove;

[0041] ② the end surface of the sliding pipe can adopt a pressing rib or increase a check ring or a clasp spring to prevent the bearing sleeve from moving axially; or a combination of the pressing rib and the limiting step is adopted for axial limiting;

[0042] ③ a shaping tool with the same shape as the sliding shaft but higher precision is used to shape the bearing sleeve, so as to ensure the fit and consistency of the bearing sleeve and the circular arc groove of the sliding pipe;

[0043] ④ the sliding shaft is inserted into the outer pipe, so that the inner sliding structure and the outer sliding structure form a pair of sliding friction pairs, the sliding shaft and the bearing sleeve adopt small gap fit, and the gap size depends on the specific requirements of the sliding force and the angular play; an inner dust cover is additionally arranged in the inner cavity of the sliding pipe and the outer side of the sliding shaft, so as to prevent foreign matters from invading;

[0044] ⑤ for the application scene with a long sliding distance, the cantilever effect is prevented, a lubricating body is arranged on the outer side wall of the end of the sliding shaft away from the outer sliding structure, so that the lubricating body and the inner surface of the connecting pipe form a sliding friction pair with gap fit; the lubricating body can be annular, the number is at least one, and the lubricating body is sintered after being pressure cast in a mold using PTFE powder.

[0045] The vehicle intermediate shaft sliding structure can greatly reduce the friction, has low sliding force, small angular play, high motion precision and high wear resistance, meets the long service life requirement, can be widely applied to various vehicle steering systems, improves the flexibility and stability of steering, and reduces the maintenance cost. Meanwhile, the added sealing structure and the supplementary structure (annular lubricating body) further improve the stability and durability of the steering system. It is verified through experiments that the sliding structure has excellent performance in the long-term use process, and has significant economic benefits and social benefits. BRIEF DESCRIPTION OF DRAWINGS

[0046] Fig. 1 is a sectional view of the slip structure of the present application;

[0047] Fig. 2 is an exploded view of the slip structure of the present application

[0048] Fig. 3 is a schematic view of the structure of the slip tube of the present application (with a shaft sleeve);

[0049] Fig. 4 is an end view of Fig. 3;

[0050] Fig. 5 is a schematic view of the structure of the slip shaft of the present application;

[0051] Fig. 6 is a schematic view of the installation of the slip shaft and the annular lubricating body of the present application;

[0052] Fig. 7 is an enlarged view of a portion of Fig. 1;

[0053] Fig. 8 is a comparison view of the rib before and after pressing of portion A of Fig. 7;

[0054] Fig. 9 is an enlarged view of portion B of Fig. 7;

[0055] Fig. 10 is a schematic view of the inner and outer slip structures of the present application with a larger engagement contact area;

[0056] Fig. 11 is a schematic view of the inner and outer slip structures of the present application with a smaller engagement contact area;

[0057] Fig. 1-2: connecting tube 1, limiting step 1-1, slip tube 2, circular arc groove 2-1, small boss 2-2, rib groove 2-3, rib 2-4, slip shaft 3, circular arc protrusion 3-1, annular groove 3-2, shaft sleeve 4, annular lubricating body 5, inner dust cover 6, outer dust cover 7, connecting shaft 8. DETAILED DESCRIPTION

[0058] Example 1

[0059] As shown in Figs. 1-2, a slip structure for a vehicle steering intermediate shaft includes an outer tube formed by the close connection of a connecting tube 1 and a slip tube 2, a slip shaft 3 disposed in the outer tube, and a shaft sleeve 4, wherein:

[0060] 1) As shown in Figs. 3-4, the inner wall of the slip tube is provided with an inner slip structure, which is four circular arc grooves 2-1 evenly and spacedly distributed in the circumferential direction, forming petal grooves;

[0061] 2) As shown in Fig. 5, the outer cylindrical surface of the slip shaft is provided with an outer slip structure, which is four circular arc protrusions 3-1 evenly distributed in the circumferential direction, to engage and transmit with the circular arc grooves with the shaft sleeve; a friction coating is sprayed on the surface of the slip shaft;

[0062] 3), as shown in Figure 3-4, the shaft sleeve is four circular arc sleeve matching the circular arc groove, and fixed in the corresponding circular arc groove; the shaft sleeve is made of three layers of composite material plate of steel plate layer, copper powder layer and PTFE composite formula layer; the sliding shaft and the sliding pipe are engaged and transmitted through the circular arc groove with the shaft sleeve and the circular arc protrusion with the friction coating, and form a pair of sliding friction pairs.

[0063] As shown in Figure 3-4, a small boss 2-2 is provided between the two adjacent circular arc grooves to prevent the shaft sleeve from sliding in the circumferential direction after installation.

[0064] Example 2

[0065] On the basis of Example 1, when the sliding pipe is located at the upper end of the connecting pipe, or for application scenarios with longer sliding distance, in order to reduce the cantilever effect, as shown in Figures 5-6, two annular grooves 3-2 are provided on the outer side wall of the sliding shaft away from the sliding pipe, and an annular lubricating body 5 is installed in the annular groove. The annular lubricating body is gap-fitted with the inner wall of the connecting pipe and forms another sliding friction pair with it. The annular lubricating body is sintered after being pressure cast with PTFE powder in a mold.

[0066] Example 3

[0067] On the basis of Example 1 or 2, as shown in Figures 7-9, the inner wall of the sliding pipe is pressed to form a rib groove 2-3 and a protruding rib 2-4, and the connecting pipe is provided with a limiting step 1-1 at the contact position with the sliding pipe to prevent the shaft sleeve from sliding axially.

[0068] Example 4

[0069] On the basis of Example 1 or 2 or 3, as shown in Figures 1-2, an inner dust cover 6 is provided at the outer end of the sliding pipe and the outer side of the sliding pipe is also provided with a corrugated outer dust cover 7 to ensure full sealing in the sliding range.

[0070] In Figure 1, the sliding shaft is connected with a connecting shaft 8 as the upper end of the sliding structure, and the other end of the connecting pipe is the lower end of the entire sliding structure and is connected with a universal joint fork.

[0071] Example 5

[0072] On the basis of Example 1, for the working conditions of transmitting large torque and requiring low sliding force, the inner and outer sliding structures with larger meshing contact area can be selected, as shown in Figure 10. The groove bottom profile line (in the circumferential direction) of each circular arc groove is composed of a single curvature circular arc line, the shaft sleeve is fitted with the corresponding circular arc groove with consistent curvature, and the outer profile line (in the circumferential direction) of each circular arc protrusion has consistent curvature with the curvature of the groove bottom profile line of the corresponding circular arc groove, so that the meshing contact area of the inner and outer sliding structures reaches the maximum.

[0073] The radius of each circular-arc groove is less than the radius of the circle on which the bottom of the four circular-arc grooves is located, so as to increase the chord height of each circular-arc groove and the torque transmission capacity of the circular-arc.

[0074] Embodiment 6

[0075] Based on the embodiment 1, for the working condition with low torque requirement and strict sliding force requirement, the inner and outer sliding structures with slightly smaller meshing contact area can be selected, as shown in Fig. 11, the bottom profile line (in the circumferential direction) of each circular-arc groove is composed of a single curvature circular-arc line, and the shaft sleeve is in close contact with the corresponding circular-arc groove with consistent curvature.

[0076] The outer profile line (in the circumferential direction) of each circular-arc protrusion is composed of three circular-arc lines with different curvatures, the curvatures of the two circular-arc lines on the outer side are consistent with the curvature of the circular-arc groove, and the curvature of the circular-arc line in the middle section is greater than the curvatures of the two circular-arc lines on the outer side, so that the sliding shaft does not contact the shaft sleeve in the middle section (in the circumferential direction) of the circular-arc protrusion, the meshing contact area is reduced, and the sliding force can be significantly reduced.

[0077] Embodiment 7

[0078] A preparation method of a sliding structure of a vehicle steering intermediate shaft, comprising:

[0079] (1) Preparation of the sliding pipe

[0080] The sliding pipe is subjected to broaching processing using pipe material, and the inner surface is broached into a predetermined inner sliding structure shape, the inner sliding structure is four circular-arc grooves uniformly distributed in the circumferential direction, and a small boss is arranged between adjacent two circular-arc grooves to prevent the shaft sleeve from sliding in the circumferential direction; the sliding pipe and the connecting pipe are connected into one body to form an outer pipe, so as to ensure that the connecting pipe and the sliding pipe are tightly connected;

[0081] (2) Preparation of the sliding shaft

[0082] ① Drawing forming is adopted to form an outer sliding structure on the outer cylindrical surface of the sliding shaft, and the outer sliding structure is a circular-arc protrusion for meshing transmission with the circular-arc groove; for the occasions with strict sliding force and angular play requirements, the outer sliding structure can be subjected to grinding processing after the drawing forming;

[0083] ② The surface of the sliding shaft is subjected to degreasing treatment and preheating treatment, and the drying temperature is 110℃-130℃;

[0084] ③ The PTFE composite spraying material after stirring is loaded into a spray gun, and the outer sliding structure surface of the sliding shaft is uniformly sprayed to form a friction coating, and the thickness of the coating is 0.005-0.015mm;

[0085] The spraying material of the friction coating is PTFE composite spraying material, and the components of the PTFE composite spraying material include PTFE, N-methyl-2-pyrrolidone, 1,2,4-trimethylbenzene, methyl isobutyl ketone and carbon black;

[0086] ④The sprayed sliding shaft is dried at 170-190℃ for 2h to enhance the bonding force;

[0087] (3) Preparation of the shaft sleeve

[0088] ①A layer of copper powder is laid on the steel plate, and sintering and heat preservation are performed to obtain a copper powder plate;

[0089] The thickness of the steel plate is 0.6-0.8mm, the copper powder is 100-200 mesh, the laying thickness is 0.20-0.30mm, the sintering temperature is 880-910℃, and the heat preservation time is 30min;

[0090] ②The surface of the copper powder plate is laid with a mud-like PTFE composite formula material, and plasticizing and heat preservation are performed to obtain a three-layer composite material plate; the laying thickness of the mud-like PTFE composite formula material is 0.01-0.10mm, the plasticizing temperature is 365-385℃, and the heat preservation time is 50min;

[0091] ③The three-layer composite material plate is subjected to rolling treatment using a finishing mill to obtain a finished three-layer composite material plate with a thickness of 0.98±0.02mm;

[0092] ④The finished three-layer composite material plate is cut into small plate materials meeting the size requirements;

[0093] ⑤The small plate materials are formed and bent into bearing shell shapes by a forming die, and the bending curvature and angle meet the product requirements;

[0094] ⑥The small plate materials are shaped using a shaping mandrel to form a finished shaft sleeve with a circular arc shape;

[0095] (4) Assembly of the sliding structure

[0096] ①The prepared circular arc finished shaft sleeve is assembled into the circular arc groove of the sliding pipe, so that the curvature of the shaft sleeve is consistent with the curvature of the corresponding circular arc groove;

[0097] ②The shaft sleeve is subjected to axial limiting using the combination of the above-mentioned rib and limiting step;

[0098] ③The shaft sleeve is shaped using a shaping tool with the same shape as the sliding shaft but higher precision to ensure the fit and consistency of the shaft sleeve and the circular arc groove of the sliding pipe;

[0099] (4) Insert the sliding shaft into the outer tube, so that the inner sliding structure and the outer sliding structure form a pair of sliding friction pairs, and a small gap is adopted between the sliding shaft and the shaft sleeve, and the size of the gap depends on the specific requirements of the sliding force and the angular play; an inner dust cover is additionally arranged on the inner cavity of the sliding tube and the outer side of the sliding shaft to prevent foreign matter from entering;

[0100] (5) For application scenarios with a longer sliding distance, prevent cantilever effect, and at the end of the sliding shaft away from the outer sliding structure, the outer side wall is provided with a PTFE annular lubricating body, so that the lubricating body and the inner surface of the connecting pipe form a gap fit sliding friction pair.

Claims

1. A vehicle steering intermediate shaft slip structure characterized by, The outer tube is integrally formed or fixedly connected by a connecting tube and a sliding tube; The outer surface of the sliding shaft is provided with an outer sliding structure, and the inner wall of the sliding tube is provided with an inner sliding structure, and the sliding shaft is engaged and transmission connected with the outer tube through the outer sliding structure and the inner sliding structure; The surface of the outer sliding structure is provided with a friction coating, and the surface of the inner sliding structure is partially or entirely provided with a shaft sleeve, and the shaft sleeve and the friction coating form a pair of sliding friction pairs.

2. The vehicle intermediate shaft slip structure of claim 1 wherein, The shaft sleeve is made of a three-layer composite plate, and the three-layer composite plate is composed of a steel plate layer, a copper powder layer and a PTFE composite formula layer from bottom to top.

3. The vehicle intermediate shaft slip structure of claim 2 wherein, The surface of the outer sliding structure is coated with a friction coating of a friction-reducing material, or a wear-resistant material, or a mixture of a friction-reducing material and a wear-resistant material.

4. The vehicle intermediate shaft slip structure of claim 2 wherein, The inner sliding structure comprises a plurality of circular-arc grooves uniformly distributed in the circumferential direction; the shaft sleeve is a circular-arc shaft sleeve matched with the circular-arc grooves and fixedly attached in the corresponding circular-arc grooves; The outer sliding structure is a plurality of circular-arc protrusions uniformly distributed in the circumferential direction to be engaged and transmission connected with the circular-arc grooves with the shaft sleeve; the number of the circular-arc grooves, the circular-arc protrusions and the circular-arc shaft sleeves is consistent and one-to-one corresponding.

5. The vehicle intermediate shaft slip structure of claim 4 wherein, The groove bottom profile line of each circular-arc groove is composed of a single-curvature circular-arc line or smoothly connected by a plurality of circular-arc lines with varying curvatures; The outer profile line of each circular-arc protrusion has a curvature locally or entirely consistent with the curvature of the groove bottom profile line of the corresponding circular-arc groove.

6. The vehicle transaxle slip structure of claim 5 wherein, The outer side end of the inner wall of the sliding tube is provided with a protruding pressing rib to prevent the shaft sleeve from axially sliding; the connecting tube is provided with a limiting step at the contact position with the sliding tube to prevent the shaft sleeve from axially sliding.

7. A vehicle intermediate shaft slip structure according to claim 1, 2, 3, 4, 5 or 6 wherein, The outer side wall of the sliding shaft at the end away from the outer sliding structure is provided with a lubricating body; the lubricating body is gap-fitted with the inner wall of the connecting tube and forms a sliding friction pair with the inner wall of the connecting tube to prevent cantilever effect.

8. The vehicle transaxle slip structure of claim 6 wherein, The outer side end of the sliding shaft is provided with an inner dust cover, and the outer side end of the sliding tube is provided with an outer dust cover.

9. The method of claim 1, wherein the method further comprises the step of: The preparation of the sliding tube comprises the following steps: ​ (1) The sliding tube is prepared by using a pipe material for broaching processing to form a predetermined inner sliding structure on the inner surface of the sliding tube, the inner sliding structure comprising a plurality of circular-arc grooves uniformly distributed in the circumferential direction and a small protrusion arranged between adjacent two circular-arc grooves to prevent the shaft sleeve from circumferentially sliding; The sliding tube is fixedly connected with the connecting tube to form an outer tube; (2) The preparation of the sliding shaft comprises the following steps: ① The outer surface of the sliding shaft is formed with an outer sliding structure by drawing forming, and the outer sliding structure is a circular-arc protrusion engaged and transmission connected with the circular-arc groove; for occasions with strict requirements on sliding force and angular play, the outer sliding structure can be ground after drawing forming; ② The surface of the sliding shaft is cleaned, degreased and preheated; ③ The PTFE composite sprayed material after stirring is loaded into a spray gun to uniformly spray the surface of the outer sliding structure of the sliding shaft to form a friction coating; ④ The sprayed sliding shaft is dried; (3) The preparation of the shaft sleeve comprises the following steps: ① A layer of copper powder is laid on a steel plate and sintered and heat preserved to obtain a copper powder plate; ② The surface of the copper powder plate is paved with a mud-like PTFE composite formula material, and plasticized and heat preserved to obtain a three-layer composite plate; ③ The three-layer composite plate is rolled to obtain a finished three-layer composite plate; ​ ​ (4) Assembling the sliding structure ① Put the prepared circular arc product shaft sleeve into the circular arc groove of the sliding tube, so that the curvature of the shaft sleeve is consistent with the curvature of the corresponding circular arc groove; ② The end face of the sliding tube can be provided with a pressing rib or a retaining ring or a snap spring to prevent the shaft sleeve from moving axially; ③ Use a shaping tool that is the same shape as the sliding shaft but has higher precision to shape the shaft sleeve to ensure the fit and consistency of the shaft sleeve and the circular arc groove of the sliding tube; ④ Insert the sliding shaft into the outer tube to form a pair of sliding friction pairs of the inner sliding structure and the outer sliding structure; add an inner dust cover to the inner cavity of the sliding tube and the outer side of the sliding shaft; ⑤ For application scenarios with a longer sliding distance, a lubricating body is arranged on the outer side wall of the end of the sliding shaft away from the outer sliding structure, so that the lubricating body and the inner surface of the connecting pipe form a sliding friction pair with a gap fit. ​ ​ ​

Images