High-stability transmission gear set for automobile parts

Abstract

The invention provides a high-stability transmission gear set for automobile parts, and relates to the technical field of transmission gear sets, the high-stability transmission gear set comprises a differential gear set, the differential gear set comprises a connecting shaft rod, a half axle gear, a planet shaft frame and a planet gear, and a driven gear is fixedly installed outside the connecting shaft rod located below a differential shell. The ends of the two connecting shaft rods are located in the middle of the planet shaft frame, the two half-axle gears are installed outside the two connecting shaft rods, the planet gears are rotatably installed on the outer side wall of the planet shaft frame, gear teeth are arranged on the surfaces of the half-axle gears and the surfaces of the planet gears, and the half-axle gears and the planet gears are meshed through the gear teeth on the surfaces of the half-axle gears and the surfaces of the planet gears. The tooth crest of each gear tooth is provided with a tooth crest edge trimming surface, and the tooth shape of the gear is slightly modified, so that the impact at the initial stage of gear meshing can be reduced, the meshing process is smoother, vibration and noise are reduced, and the smoothness of gear operation is improved.

Description

Technical Field

[0001] This invention belongs to the field of transmission gear set technology, and more specifically, relates to a high-stability transmission gear set for automotive parts. Background Technology

[0002] In fields such as automotive differentials that involve planetary gears and half-shaft gear transmissions, traditional design and manufacturing technologies have many problems that seriously affect the performance, reliability, and service life of the transmission system.

[0003] Gear meshing problem

[0004] Tooth tip collision: Traditional planetary gears and half-shaft gears are not designed with sufficient consideration for the initial meshing stage and changes in speed. Rigid collisions easily occur between the tooth tips and the roots of opposing teeth. This not only generates significant noise but also accelerates gear wear, shortens gear lifespan, and in severe cases, may even damage the gears, affecting the normal operation of the entire transmission system.

[0005] Material heat treatment issues

[0006] Improper control of carburized layer depth: Traditional material heat treatment processes make it difficult to precisely control the depth of the carburized layer. If the carburized layer at the tooth root is too thin, it may lead to insufficient tooth root strength and easy breakage under stress. On the other hand, if the carburized layer at the tooth tip is too thick, it will affect the meshing clearance, making the gear transmission unsmooth and generating vibration and noise.

[0007] Planetary carrier structure problem

[0008] Stress concentration and deformation: Under high torque conditions, stress concentration is severe around the shaft bore of traditional planetary carriers, leading to slight deformation of the carrier. This not only affects the normal meshing of the planetary gears and axle gears but also reduces the load-bearing capacity of the planetary carrier, limiting the torque transmission capability of the transmission system and failing to meet the requirements of some applications with high power demands.

[0009] Lubrication problem

[0010] Insufficient lubrication at high speeds: Under high-speed differential conditions, traditional lubrication path designs cannot ensure that lubricating oil is sprayed to the meshing area in a timely and effective manner, making it difficult to form a stable oil film. This leads to increased friction between gears, accelerated wear, and seriously affects the service life and transmission efficiency of the gears.

[0011] In summary, existing planetary gear and half-shaft gear transmission technologies have significant shortcomings in tooth profile design, material heat treatment, planetary carrier structure, and lubrication, and cannot meet the demands of modern industry for efficient, reliable, and long-life transmission systems. Summary of the Invention

[0012] To address the aforementioned technical problems, this invention provides a highly stable transmission gear set for automotive parts.

[0013] A high-stability transmission gear set for automotive parts includes a differential gear set. The differential gear set includes connecting shafts, half-shaft gears, a planetary carrier, and planetary gears. A driven gear is fixedly installed on the connecting shafts located below the differential housing. The ends of the two connecting shafts are located in the middle of the planetary carrier, and two half-shaft gears are installed outside the two connecting shafts. Several planetary gears are rotatably installed on the outer wall of the planetary carrier. The surfaces of the half-shaft gears and planetary gears are provided with gear teeth, and the half-shaft gears and planetary gears mesh with each other through the gear teeth on their own surfaces. Each gear tooth has a tooth tip trimming surface at the tooth tip, and the gear teeth on the surfaces of the half-shaft gears and planetary gears have a tooth-direction drum-shaped trimming surface formed in the middle of the tooth surface.

[0014] Preferably, several gear shafts are fixedly mounted on the surface of the planetary shaft carrier, and an annular bushing is fixedly mounted on the surface of each gear shaft. The annular bushing is close to the root of the gear shaft, the thickness of the annular bushing is 3mm, and the diameter of the annular bushing is larger than the inner diameter of the planetary gear. The tooth tip trimming surface at the tooth tip of each gear tooth is trimmed with a linear trimming of 0.03mm. The tooth direction drum-shaped trimming surface of each gear tooth protrudes 0.01mm from the middle of the tooth surface in the tooth width direction to the tooth thickness direction. Each planetary gear bore is provided with a roller-rolled surface on the inner wall of the shaft hole, and each roller-rolled surface on the inner wall of the shaft hole is reinforced by roller rolling.

[0015] Preferably, several directional oil injection holes with a diameter of 2mm are provided along the tangential direction near the meshing point of the planetary gear and the half-shaft gear on the planetary carrier. The directional oil injection holes adopt a stepped design. The interior of the directional oil injection holes includes a front oil injection hole and a rear oil injection hole. The diameter of the front oil injection hole is 3mm and the diameter of the rear oil injection hole is 2mm. The directional oil injection holes are used to deliver lubricating oil. Each gear tooth on the planetary gear has an annular oil reservoir at the root of the tooth. Each annular oil reservoir is used to store a small amount of lubricating oil from the directional oil injection holes. The differential gear set includes two differential housings facing opposite directions. The interior of both differential housings has a bushing groove. The two differential housings are installed outside the planetary carrier and the half-shaft gear.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] I. Regarding micro-molding of tooth profiles, edge trimming of the tooth tips of planetary gears and half-shaft gears can prevent rigid collisions between the tooth tips and the roots of opposing teeth during the initial meshing stage, especially when the speed changes. Cushioning of the tooth direction can compensate for slight axis parallelism errors during gear installation, ensuring uniform load distribution along the tooth width during meshing and preventing localized overloads at both ends. This can be achieved using the relevant functions of a CNC gear grinding machine, without the need to change cutting tools, making it convenient and quick.

[0018] II. Regarding the fine-tuning of material heat treatment, controlling the deviation of the carburized layer depth can avoid abnormal meshing clearance caused by the carburized layer at the tooth root being too thin or the carburized layer at the tooth tip being too thick. Extending the low-temperature tempering holding time and adopting a stepped cooling method can reduce the slow change in gear size caused by the decomposition of residual austenite, which is conducive to improving the stability of gear size and ensuring the stability of meshing clearance.

[0019] Thirdly, regarding the local reinforcement of the planetary carrier, adding an annular boss around the planetary carrier shaft hole can reduce stress concentration at the shaft hole and reduce the slight deformation of the planetary carrier under high torque; rolling reinforcement of the inner wall of the shaft hole can improve the wear resistance of the shaft hole and help maintain the fit clearance. These improvements can enhance the supporting rigidity of the planetary carrier.

[0020] IV. In terms of lubrication path optimization, the newly added directional oil injection holes allow lubricating oil to be directly sprayed into the meshing area, forming a stable oil film even under high-speed differential conditions. An oil reservoir is designed at the transition fillet of the planetary gear tooth root, which can carry the stored lubricating oil into the meshing area under low-speed or short-term oil shortage conditions, avoiding increased wear caused by insufficient instantaneous lubrication and enhancing the stability of the oil film in the meshing area. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the differential gear set of the present invention;

[0022] Figure 2 This is a schematic diagram of the planetary bearing structure of the present invention;

[0023] Figure 3 This is a schematic diagram of the differential housing structure of the present invention;

[0024] Figure 4 This is a schematic diagram of the half-shaft gear structure of the present invention;

[0025] Figure 5 This is a schematic diagram of the gear shaft structure of the present invention;

[0026] Figure 6 This is a schematic diagram of the meshing structure of the half-shaft gear and planetary gear 2 of the present invention;

[0027] Figure 7 This is the present invention. Figure 6 A magnified structural diagram at point A;

[0028] Figure 8 This is a schematic diagram of the overall structure of the planetary gear of the present invention;

[0029] Figure 9 This is the present invention. Figure 8 Enlarged overall structural diagram at point B;

[0030] Figure 10 This is a schematic diagram of the overall structure of the directional oil injection hole of the present invention.

[0031] In the figure, the correspondence between the component names and the attached drawing numbers is as follows: 1. Differential gear set; 11. Sleeve groove; 12. Differential housing; 13. Driven gear; 14. Connecting shaft; 15. Ball bearing; 16. Half shaft gear; 17. Planetary shaft carrier; 18. Gear shaft; 19. Annular bushing; 2. Planetary gear; 21. Gear teeth; 22. Tooth direction drum-shaped correction surface; 23. Tooth tip edge correction surface; 24. Shaft hole inner wall rolling surface; 25. Annular oil reservoir; 26. Front oil injection hole; 27. Rear oil injection hole; 3. Directional oil injection hole. Detailed Implementation

[0033] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0034] Please see Figure 1 Figure 1 shows a differential gear set. This invention provides a high-stability transmission gear set for automotive parts, including a differential gear set 1. The differential gear set 1 includes connecting shafts 14, half-shaft gears 16, a planetary carrier 17, and planetary gears 2. A driven gear 13 is fixedly mounted on the connecting shafts 14 located below the differential housing 12. The ends of the two connecting shafts 14 are located in the middle of the planetary carrier 17, and two half-shaft gears 16 are mounted on the outside of the two connecting shafts 14. Several planetary gears 2 are rotatably mounted on the outer wall of the planetary carrier 17. The half-shaft gears 16 and the driven gears 2... The surface of the planetary gear 2 is provided with gear teeth 21, and the half-shaft gear 16 and the planetary gear 2 mesh with each other through the gear teeth 21 on their own surfaces. Each gear tooth 21 has a tooth tip trimming surface 23 at the tooth tip, and the gear teeth 21 on the surfaces of the half-shaft gear 16 and the planetary gear 2 have a tooth direction drum-shaped correction surface 22 in the middle of the tooth surface. The differential gear set 1 includes two differential housings 12 facing opposite directions. The interior of the two differential housings 12 is provided with a sleeve groove 11, and the two differential housings 12 are installed on the planetary shaft carrier 17 and the half-shaft gear 16.

[0035] Several gear shafts 18 are fixedly mounted on the surface of the planetary carrier 17, and an annular sleeve 19 is fixedly mounted on the surface of each gear shaft 18. The annular sleeve 19 is close to the root of the gear shaft 18, and its thickness is 3mm. The diameter of the annular sleeve 19 is larger than the inner diameter of the planetary gear 2. The annular sleeve 19 effectively reduces the stress concentration coefficient at the shaft hole of the planetary gear 2, reduces the slight deformation of the planetary carrier under high torque, and avoids the planetary gear being overloaded due to the tilt of the shaft hole. The tooth tip trimming surface 23 at the tooth tip of each gear tooth 21 adopts a linear trimming of 0.03~0.05mm to avoid the initial stage of gear meshing ( Especially when the rotational speed changes, the rigid collision between the tooth tip and the root of the opposing tooth is a problem. Traditional tooth tips have a right-angle transition, which can easily cause a "tooth-biting" impact at the moment of meshing. After micro-repair, a smooth transition is formed, which reduces the peak contact stress. The tooth-direction drum-shaped correction surface 22 of each gear tooth 21 protrudes 0.01 to 0.02 mm from the middle of the tooth surface to the tooth thickness direction in the tooth width direction, and narrows at both ends in a linear trend to offset the slight axis parallelism error during gear installation (allowable error ≤ 0.02 mm / m), ensuring that the load is evenly distributed along the tooth width during meshing and avoiding local overload at both ends (traditional flat tooth surfaces are prone to the problem of "contact at both ends and suspension in the middle").

[0036] Each planetary gear 2 has a bore inner wall rolling surface 24, and each bore inner wall rolling surface 24 is reinforced by rolling to reduce the surface roughness of the bore inner wall, improve the wear resistance of the bore, and form a residual compressive stress layer of 0.1-0.2 mm. Several directional oil injection holes 3 with a diameter of 2 mm are opened tangentially near the meshing point between the planetary gear 2 and the half-shaft gear 16 on the planetary shaft carrier 17. The directional oil injection holes 3 are connected to the internal lubrication oil passages of the planetary shaft carrier 17 (using the pumping effect of the differential gear set 1 to supply oil). The directional oil injection holes 3 adopt a stepped design. The interior of the directional oil injection hole 3 includes a front oil injection hole 26 and a rear oil injection hole 27. The diameter of the nozzle 26 is 3mm, and the diameter of the rear oil injection hole 27 is 2mm, so that the lubricating oil is directly sprayed into the meshing area. Even under high-speed differential conditions (such as sharp turns), a stable oil film can still be formed, reducing vibration caused by dry friction. The directional oil injection hole 3 is used to deliver lubricating oil. Each gear tooth 21 on the planetary gear 2 has an annular oil reservoir 25 at the root of the tooth. Each annular oil reservoir 25 is used to store a small amount of lubricating oil from the directional oil injection hole 3. The annular oil reservoir 25 stores a small amount of lubricating oil. Under low-speed or short-term oil shortage conditions (such as the moment of cold start), the rotation of the planetary gear 2 carries the oil in the annular oil reservoir 25 into the meshing area, avoiding the aggravation of wear caused by insufficient instantaneous lubrication.

[0037] Working principle: The external drive gear meshes with the driven gear 13, causing the driven gear 13 to rotate. When the car is traveling straight, the rotation of the driven gear 13 will cause the entire assembly to rotate. When the driven gear 13 rotates, it will cause the differential gear set 1 to rotate as a whole. When the car needs to turn, a speed difference occurs between the two connecting shafts 14. At this time, the two half-shaft gears 16 and four planetary gears 2 inside the differential housing 12 mesh and rotate. The sleeve groove 11 inside the differential gear set 1 is used to fit the gear shaft 18. When the planetary gear 2 rotates, the annular sleeve 19 on the surface of the gear shaft 18 can provide greater torque protection for the planetary gear 2, improving the safety between the gear shaft 18 and the planetary gear 2. During normal operation, oil from the oil pump will be sprayed onto the half-shaft gears 16 and planetary gears 2 through the directional oil injection holes 3. The multiple annular oil reservoirs 25 inside the planetary gears 2 can temporarily store lubricating oil, thereby improving the smoothness of meshing between the two and reducing the degree of damage.

[0038] The half-shaft gear 16 and planetary gear 2 in this device undergo fine-tuning during material heat treatment to improve dimensional stability.

[0039] Improved areas: Uniformity of heat treatment on gear tooth surfaces and core

[0040] Process steps:

[0041] Carburized layer depth deviation control: The upper and lower deviations of the existing carburized layer depth (conventional 0.8~1.2mm) are tightened from ±0.15mm to ±0.08mm. By optimizing the carbon potential curve of the carburizing furnace (carbon potential 1.0% in the first 2 hours and reduced to 0.8% in the last 3 hours), the difference in carburized layer depth between the tooth root and the tooth tip is ensured to be ≤0.1mm.

[0042] Function: To prevent abnormal meshing clearance caused by excessively thin carburized layer at the tooth root (prone to fatigue fracture) or excessively thick carburized layer at the tooth tip (prone to embrittlement), and to reduce dimensional deformation after long-term use.

[0043] Extended low-temperature tempering holding time: Based on the existing tempering process (gear shaft 180℃×2 hours), the holding time of the directional oil injection hole is extended by 3 minutes, and a "step cooling" method is adopted (gear shaft 180℃ → ball bearing 150℃ → differential housing 1 planetary gear 2℃, directional oil injection hole 3 minutes in each stage), so that the residual austenite content is reduced from ≤8% to ≤5%.

[0044] Function: To reduce the slow change in gear dimensions caused by the decomposition of residual austenite (tooth thickness deviation ≤0.01mm after long-term use) and ensure the stability of meshing clearance.

[0045] The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A high-stability transmission gear set for automotive parts, comprising a differential gear set (1), characterized in that: The differential gear set (1) includes connecting shafts (14), half-shaft gears (16), planetary carriers (17), and planetary gears (2). A driven gear (13) is fixedly installed on the connecting shafts (14) located below the differential housing (12). The ends of the two connecting shafts (14) are located in the middle of the planetary carriers (17), and two half-shaft gears (16) are installed on the outside of the two connecting shafts (14). Several planetary gears (2) are rotatably mounted on the connecting shafts (14). The outer wall of the planetary shaft carrier (17), the surface of the half-shaft gear (16) and the planetary gear (2) are provided with gear teeth (21), and the half-shaft gear (16) and the planetary gear (2) mesh with each other through the gear teeth (21) on their own surfaces. Each gear tooth (21) has a tooth tip trimming surface (23) at the tooth tip, and the gear teeth (21) on the surface of the half-shaft gear (16) and the planetary gear (2) have a tooth direction drum-shaped trimming surface (22) formed in the middle of the tooth surface.

2. The high-stability transmission gear set for automotive parts as described in claim 1, characterized in that, Several gear shafts (18) are fixedly mounted on the surface of the planetary shaft carrier (17), and an annular bushing (19) is fixedly mounted on the surface of each gear shaft (18), with the annular bushing (19) close to the root of the gear shaft (18).

3. The high-stability transmission gear set for automotive parts as described in claim 1, characterized in that, The thickness of the annular bushing (19) is 3 mm, and the diameter of the annular bushing (19) is greater than the inner diameter of the planetary gear (2).

4. The high-stability transmission gear set for automotive parts as described in claim 1, characterized in that, The tooth tip trimming surface (23) at the tip of each gear tooth (21) is trimmed with a linear trimming of 0.03 mm.

5. The high-stability transmission gear set for automotive parts as described in claim 1, characterized in that, The tooth-direction drum-shaped correction surface (22) of each gear tooth (21) protrudes 0.01 mm in the tooth width direction through the middle of the tooth surface towards the tooth thickness direction.

6. The high-stability transmission gear set for automotive parts as described in claim 1, characterized in that, Each planetary gear (2) has a bore diameter with a roller-rolled surface (24) on the inner wall of the shaft hole, and each roller-rolled surface (24) on the inner wall of the shaft hole is reinforced by roller rolling.

7. The high-stability transmission gear set for automotive parts as described in claim 1, characterized in that, Several directional oil injection holes (3) with a diameter of 2 mm are provided along the tangential direction at the position of the planetary shaft carrier (17) near the meshing point of the planetary gear (2) and the half shaft gear (16).

8. The high-stability transmission gear set for automotive parts as described in claim 7, characterized in that, Several directional oil injection holes (3) adopt a stepped design. The interior of the directional oil injection hole (3) includes a front oil injection hole (26) and a rear oil injection hole (27). The diameter of the front oil injection hole (26) is 3mm, and the diameter of the rear oil injection hole (27) is 2mm. The directional oil injection hole (3) is used to deliver lubricating oil.

9. The high-stability transmission gear set for automotive parts as described in claim 8, characterized in that, Each gear tooth (21) on the planetary gear (2) has an annular oil reservoir (25) at the root of the tooth, and each annular oil reservoir (25) is used to store a small amount of lubricating oil from the directional oil injection hole (3).

10. The high-stability transmission gear set for automotive parts as described in claim 1, characterized in that, The differential gear set (1) includes two differential housings (12) facing opposite directions. Both differential housings (12) have sleeve grooves (11) inside, and the two differential housings (12) are mounted on the planetary carrier (17) and the half shaft gear (16).

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