Motor vehicle main speed reducer assembly free of pre-tightening and adjusting shim

Abstract

The invention discloses a motor vehicle main reducer assembly free of pre-tightening and adjusting gaskets, which comprises a main bevel gear, a double-row bearing unit assembly and a gear shaft, an inner ring of the double-row bearing unit assembly is matched with a shaft neck of the gear shaft, an outer ring of the double-row bearing unit assembly is matched with a bearing seat, and the double-row bearing unit assembly is pressed through a pressing plate connected to the bearing seat. According to the structure of the device, the heat productivity of the bearing is greatly reduced, the heat dissipation efficiency is greatly improved, and the thermal expansion and cold contraction of each part of the bearing are basically kept consistent, so that the clearance value of the bearing is ensured to be between 0 and a tiny value, and a main speed reducer assembly is always in an optimal working state. Meanwhile, due to the fact that the length of the bearing is short, the installation height of the main speed reducer assembly is shortened, arrangement is more compact, and an adjusting gasket is omitted. The rigidity, precision and efficiency of the main speed reducer assembly are greatly improved, the service life of the main speed reducer assembly is greatly prolonged, an engine with higher horsepower and a retarder with higher torque can be assembled, and much convenience and support are provided for rear engine vehicle types.

Description

Technical Field

[0001] This invention relates to the field of motor vehicle drive axles, specifically a motor vehicle main reducer assembly that requires no preload and no adjustment shims. Background Technology

[0002] Main reducer assembly ( Figure 14 , 15 The main reducer is a core component of the drive axle. Its function is to change the transmission direction of the torque from the drive shaft to the wheel ends of the rear axle, and to significantly reduce the speed of the drive shaft. In the main reducer assembly, there are two back-to-back single-row tapered roller bearings used to bear the load and torque borne by the main bevel gear.

[0003] Most existing drive axle main reducer assemblies use hypoid gears for their main bevel gears. These gears have high strength, a large number of meshing teeth, smooth operation with low noise, and high load-bearing capacity. However, they require high precision and stability in installation and operation. The axial clearance of the two tapered roller bearings in the main reducer assembly has the greatest impact on the normal operation and fatigue life of the main bevel gears. If the preload is too high when preloading these two tapered roller bearings, resulting in too small a bearing clearance, it will intensify the friction between the rollers and the inner and outer races, leading to increased vibration and significantly affecting transmission efficiency, even to the point of jamming the drive axle transmission system. If the preload is too low, it will produce a large clearance, greatly reducing the rigidity of the main reducer assembly and also generating significant vibration. Large clearance also directly affects the normal meshing of the driving and driven gears, reducing the number of teeth meshing simultaneously, decreasing the working area of ​​the gear pair, and causing stress concentration, ultimately leading to a significant reduction in the fatigue life of the gear pair.

[0004] Furthermore, during operation, the two tapered roller bearings in the main reducer assembly experience significant axial and radial forces due to the large axial force on the bearing closest to the large end of the main bevel gear. The heat generated by this sliding friction between the large flange of the inner ring and the large end face of the roller is far greater than the heat generated by the rolling friction between the roller and the inner and outer raceways. Additionally, the inner ring's inner bore connects to the gear shaft, and both the inner ring and gear shaft are located at the heart of the main reducer assembly, meaning heat can only be dissipated through gear oil and the small end of the gear shaft, resulting in poor heat dissipation. Conversely, the heat generated by the rolling friction between the outer ring and the roller is relatively... The outer ring has a small clearance, and the outer diameter of the outer ring is an interference fit with the inner bore of the bearing housing. The surface area of ​​the outer ring is about twice that of the inner bore. Therefore, the heat generated by rolling friction between the outer ring and the rollers is easily transferred through the bearing housing and dissipated into the air, causing the temperature rise of the inner ring to be much higher than that of the outer ring. In other words, the expansion of the inner ring is much greater than that of the outer ring, resulting in a smaller clearance value after the bearing has been running. If the clearance is not large enough during preload, the bearing is prone to seizing. If the clearance is designed to be too large during preload, the rigidity of the gear shaft will be too small, and the working surface of the gear pair will be in an abnormal working state. All of these factors seriously affect the normal meshing of the gear pair and shorten its fatigue life. Therefore, in the assembly of existing main reducer assemblies, it is necessary to control both the magnitude of the preload and the magnitude of the axial clearance of the bearing. However, even so, it is still impossible to guarantee the rigidity of the gear shaft and the normal meshing of the gear pair. Therefore, the current solution is to add two tapered roller bearings on the gear shaft (see...). Figure 18 and 19 The distance between bearings I1002 and II1003 in the structure is used to resolve this contradiction. This is because the cantilever support structure mounts two tapered roller bearings on the shaft on one side of the large end of the main bevel gear. Figure 14 Furthermore, the bearing closest to the gear is a large tapered angular bearing. As the previous analysis shows, to prevent the two bearings from seizing during operation, there must be a sufficiently large clearance. If the two bearings are too close together (see...),... Figure 18 When the main bevel gear is subjected to radial force, the center of force on the main bevel gear will shift by a distance δ1. Such a large offset cannot guarantee the rigidity of the gear shaft, and the gear pair cannot mesh properly; only by increasing the distance between the two bearings (see...) Figure 19When the main bevel gear is subjected to radial force, the center of force on the main bevel gear will shift by a distance δ2. Compared with δ1, δ2 is much smaller. Even if the rigidity of the main bevel gear shaft and the normal meshing requirements of the gear pair are barely met, it is only a temporary solution. It also makes the height of the main reducer assembly too high. Especially for rear-engine vehicles, the excessively high main reducer assembly not only leads to insufficient installation space for the drive shaft, but also easily causes the equivalent angle between the drive shaft and the main reducer assembly to be too large, resulting in excessive angular acceleration, which will cause vibration to the main and driven gears, thus causing resonance and abnormal noise of the main reducer assembly. In addition, the bearing clearance has not been reduced, and vibration, noise and temperature rise during bearing operation still exist.

[0005] Existing main reducer assembly straddle-type support structure (see...) Figure 15 The key feature of this type of gear is that both ends of the main bevel gear are supported by bearings. This significantly increases the support rigidity and reduces the load on the tapered roller bearings on the main bevel gear shaft, improving gear meshing conditions. Therefore, the load-bearing capacity of the gear is higher than that of the cantilever type. The working conditions of the two tapered roller bearings on the gear shaft are only an improvement over the cantilever structure; the problem is not fundamentally solved. Furthermore, the straddle-type support requires bearing housings on the main reducer assembly housing to support the guide bearings (see...). Figure 15 This results in a complex housing structure for the main reducer assembly, leading to high manufacturing costs. Although the distance between the two back-to-back single-row tapered roller bearings mounted on the journal at the large end of the main bevel gear is reduced compared to the cantilever structure, it still cannot fully meet the height requirements of the main reducer assembly for rear-engine vehicles.

[0006] Regardless of whether it's the cantilever structure or the straddle-type support structure mentioned above, in order to precisely control the rigidity of the main reducer assembly and the normal meshing of the gear pairs, existing main reducer assemblies must also have adjusting shims installed between the inner rings of the two tapered roller bearings (see...). Figure 14 , Figure 15 The adjusting shim 8) controls the axial clearance by controlling the width of the adjusting shim, thereby achieving precise control of the rigidity of the main reducer assembly and the normal meshing of the gear pair. However, controlling the clearance between the inner rings of the two tapered roller bearings is labor-intensive, inefficient, and costly. Even with automatic detection of various parameters by the machine, it is still impossible to eliminate defective products. As a result, the first-time assembly pass rate is only about 80%. Defective products need to be repeatedly disassembled, the thickness of the adjusting shim needs to be corrected, and then reinstalled.

[0007] In summary, the clearance of the bearing on the main bevel gear shaft of the main reducer assembly has a significant impact on the vibration, noise, temperature rise, load and fatigue life of the main reducer assembly. The optimal working condition is that the bearing on the large end side of the main bevel gear always operates under a condition of 0 clearance. Summary of the Invention

[0008] The purpose of this invention is to provide a motor vehicle main reducer assembly that requires no preload and no adjustment shims, including a main bevel gear, a double-row bearing unit assembly, and a gear shaft.

[0009] The gear shaft and the main bevel gear are an integral structure.

[0010] The gear shaft is equipped with a double-row bearing unit assembly.

[0011] The double-row bearing unit assembly includes a first row of tapered roller bearings and a second row of tapered roller bearings.

[0012] The first row of tapered roller bearings is located on the side closest to the main bevel gear.

[0013] The first row of tapered roller bearings includes an inner ring I, rollers I, and outer flanges I.

[0014] The second row of tapered roller bearings includes an inner ring II, rollers II, and outer flanges II.

[0015] The first and second rows of tapered roller bearings share the same outer ring. The outer ring is a hollow rotating body structure. The inner wall of the outer ring includes outer raceway I and outer raceway II.

[0016] The outer ring is fitted with outer flange I and outer flange II at its two ends respectively. Outer flange I and outer flange II are respectively located near the outer raceway I and outer raceway II.

[0017] The outer flange I / outer flange II and the outer ring are either a single part or two parts that are attached together.

[0018] The inner ring I and inner ring II are assembled on the gear shaft.

[0019] Furthermore, the inner ring I and inner ring II are coaxially and closely assembled on the gear shaft.

[0020] The inner ring I is a hollow rotating structure. The outer wall of the inner ring I is divided into a small flange I and an inner raceway I. The inner raceway I is located near the outer flange I. The taper of the inner raceway I is symmetrically assembled with the taper of the outer raceway I in the same direction, and the two together form an annular space I. Several rollers I are assembled within the annular space I.

[0021] The inner ring II is a hollow rotating structure. The outer wall of the inner ring II is divided into a small flange II and an inner raceway II. The inner raceway II is located near the outer flange II. The taper of the inner raceway II is symmetrically assembled with the taper of the outer raceway II in the same direction, and the two together form an annular space II. Several rollers II are assembled within the annular space II.

[0022] The end face of the small flange I of the inner ring I and the end face of the small flange II of the inner ring II are fitted together.

[0023] Furthermore, the taper of inner raceway I is greater than the taper of inner raceway II.

[0024] Furthermore, the inner holes of both outer flange I and outer flange II are tapered holes.

[0025] The taper of the tapered hole on the outer flange I is parallel to the axis of roller I. The taper of the tapered hole on the outer flange II is parallel to the axis of roller II.

[0026] Furthermore, when the outer edge I / outer edge II and the outer ring are an integral structure, an arc-shaped groove is provided between the end face of the outer edge I / outer edge II and the outer ring, and the central angle corresponding to the arc-shaped groove is 270°.

[0027] Furthermore, when the outer retaining edge I adopts a split structure, the outer retaining edge I is a hollow, stepped rotating structure, including a conical segment I and a cylindrical segment I. The conical segment I and the cylindrical segment I are connected by a stepped surface I.

[0028] The conical section I and the outer raceway I of the outer ring are in a clearance fit. The stepped surface I is in contact with the end face I of the outer ring. The end face I is the end closest to the outer raceway I.

[0029] When the outer retaining edge II adopts a split structure, the outer retaining edge II is a hollow, stepped rotating structure, including a conical segment II and a cylindrical segment II. The conical segment II and the cylindrical segment II are connected by a stepped surface II.

[0030] The conical section II and the outer raceway II of the outer ring are in a clearance fit. The stepped surface II is in contact with the end face II of the outer ring. The end face II is the end closest to the outer raceway II.

[0031] Furthermore, the outer raceway I and the outer raceway II are connected by an arc-shaped transition section.

[0032] Furthermore, the contact angle of the first row of tapered roller bearings is 10° to 45°. The contact angle of the second row of tapered roller bearings is 0° to 44°.

[0033] Furthermore, the first row of tapered roller bearings also includes a retainer I. The retainer I is installed within an annular space I. A plurality of rollers I are assembled within the window of the retainer I.

[0034] The second row of tapered roller bearings also includes a retainer II. The retainer II is installed within an annular space II. Several rollers II are assembled within the window of the retainer II.

[0035] Furthermore, the main reducer assembly also includes a bearing flange cover, a bearing housing, a flange, and a pressure plate.

[0036] The gear shaft is assembled in the inner ring I and inner ring II of the double row bearing unit assembly. One end of the gear shaft is connected to the main bevel gear through the stepped surface III, and the other end is connected to the flange through a spline. The flange, inner ring I and inner ring II are clamped on the gear shaft by a pressure plate.

[0037] The small flange I end of the inner ring I contacts the small flange II end of the inner ring II, while the inner raceway I end of the inner ring I abuts against the stepped surface III.

[0038] The small flange II end of the inner ring II contacts the small flange I end of the inner ring I, while the inner raceway II end of the inner ring II abuts against the flange.

[0039] The double-row bearing unit assembly is assembled in the inner hole of the bearing housing.

[0040] The outer flange I, outer flange II, and outer ring are axially positioned by the stepped surface IV, and are clamped in the inner hole of the bearing housing by the flange cover. The bearing flange cover is fastened to the side of the bearing housing near the main bevel gear with screws.

[0041] The technical effects of this invention are undeniable, and its beneficial effects are as follows:

[0042] A. This invention has advantages such as good assembly performance, compact structure, light weight, large load capacity, high transmission efficiency, low temperature rise, low noise, low cost, no need for pre-tightening, no need for adjusting shims, and ultra-long fatigue life;

[0043] B. Based on the force conditions of the main bevel gear, this invention innovatively designs a double-row bearing unit assembly. Since the second row of bearings in this assembly only bears pure radial loads and occasional axial loads, the contact angle of the second row bearings is reduced to a very small value, thus eliminating the large derived axial loads generated by the large cone angle in existing bearings (see...). Figure 16 Q 62 ), reduced to a negligible level (see Figure 17 Q4 is the radial force (and due to the small contact angle, there is almost no derived axial force). On the one hand, the derived axial load is greatly reduced, saving energy. On the other hand, the significant reduction in derived axial load greatly reduces the heat generation of the bearing, so that the clearance value of the double row bearing unit assembly 4 assembled on the main bevel gear shaft is between 0 and a very small value, and the same clearance is maintained during operation. This keeps the main reducer assembly of the vehicle in the optimal working state of near-zero clearance, greatly extending the maintenance-free mileage and life of the main reducer assembly of the vehicle.

[0044] C. The bearing unit of this invention has a short overall length, which can significantly shorten the height of the main gear shaft, resulting in a shorter installation height of the main reducer assembly, a more compact layout, and a reduced transmission shaft angle. This is beneficial for the overall layout of a rear-mounted engine and helps reduce noise and vibration. Furthermore, it significantly optimizes and simplifies the installation and adjustment procedure of the main bevel gear support bearing, eliminating the process and steps of controlling the preload between the two tapered roller bearings of the main reducer assembly using adjusting shims. This greatly improves the rigidity, precision, efficiency, and lifespan of the main reducer assembly. It can be equipped with engines with higher horsepower and retarders with higher torque, providing numerous conveniences and support for rear-engine vehicles. Attached Figure Description

[0045] Figure 1 A schematic diagram of a motor vehicle main reducer assembly that requires no preload and no adjustment shims;

[0046] Figure 2 This is a schematic diagram of a double-row bearing unit assembly 4.

[0047] Figure 3 Product schematic diagram of a double-row bearing unit assembly 4, in which two outer flanges and an outer ring are integrated into a single part;

[0048] Figure 4 A schematic diagram of a double-row bearing unit assembly 4, which consists of three parts: two outer flanges and one outer ring.

[0049] Figure 5 This is a schematic diagram showing the axial clearance of the bearing and its relative bearing life.

[0050] Figure 6 Schematic diagram of the outer ring of the double row bearing unit assembly;

[0051] Figure 7 Schematic diagram of the inner ring of the second row of tapered rollers in double-row bearing unit assembly 4;

[0052] Figure 8 A schematic diagram of the inner ring of the first row of tapered rollers in the double-row bearing unit assembly 4;

[0053] Figure 9 A schematic diagram of the second row of tapered roller bearings in the double-row bearing unit assembly 4;

[0054] Figure 10 A schematic diagram of the first row of tapered roller bearings in the double-row bearing unit assembly 4;

[0055] Figure 11 A schematic diagram of the retainer for the second row of tapered roller bearings in the double-row bearing unit assembly 4;

[0056] Figure 12 A schematic diagram of the retainer for the first row of tapered roller bearings in the double-row bearing unit assembly 4;

[0057] Figure 13 The diagram shows the outer flange, where (a) is a schematic diagram of the outer flange of the first row tapered roller bearing in the double row bearing unit assembly 4; and (b) is a schematic diagram of the outer flange of the second row tapered roller bearing in the double row bearing unit assembly 4.

[0058] Figure 14 A schematic diagram of an existing cantilever main reducer assembly;

[0059] Figure 15 This is a schematic diagram of an existing straddle-type main reducer assembly, which is a structural schematic diagram of using two sets of single-row tapered roller bearings and one set of single-row support guide bearings;

[0060] Figure 16 A schematic diagram of the force analysis of an existing main reducer assembly;

[0061] Figure 17 This is a schematic diagram of the force analysis of a main reducer assembly that requires no preload and no adjustment shims according to the present invention;

[0062] Figure 18 This is a schematic diagram showing the impact of the small distance between the two bearings in the existing main reducer assembly on the stiffness of the main bevel gear and the meshing of the main and driven gears.

[0063] Figure 19 This diagram illustrates the impact of increasing the distance between the two tapered roller bearings in the existing main reducer assembly on the stiffness of the main bevel gear and the meshing of the driving and driven gears.

[0064] Figure 20 This is a schematic diagram showing that even a large temperature rise does not affect the increase in bearing clearance of the flange of the double-row bearing unit assembly.

[0065] In the diagram: 1. Main bevel gear; 2. Bearing flange cover; 3. Bearing housing; 4. Double row bearing unit assembly; 5. Gear shaft; 6. Flange; 7. Pressure plate; 41. First row tapered roller bearing; 42. Second row tapered roller bearing; 401. Inner ring I; 402. Roller I; 403. Retainer I; 404. Outer flange I; 405. Outer flange II; 406. Retainer II; 407. Roller II; 408. Inner ring II; 409. Small flange I; 4011. Inner raceway I; 4012. Small flange II; 4091. Inner raceway II; 4092. Outer raceway I; 4051. Outer raceway II; 4052. Conical section I; 4041. Cylindrical section I; 4042. Stepped surface I; 4043. Conical section II; 4061. Cylindrical section II; 4062. Stepped surface II; 4063. Stepped surface III; 401. Stepped surface IV;

[0066] Adjusting shim 8, main bevel gear Ⅲ1001, bearing 1002, bearing 1003. Detailed Implementation

[0067] The present invention will be further described below with reference to embodiments, but it should not be construed that the scope of the present invention is limited to the following embodiments. Various substitutions and modifications made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention should be included within the scope of protection of the present invention.

[0068] Example 1:

[0069] As is well known, the clearance of a bearing has a significant impact on bearing load, life, temperature rise, noise, and vibration. Figure 5 This is a schematic diagram showing the relationship between axial clearance and relative life of a roller bearing. Zero clearance represents the optimal operating state for the bearing, as it results in the longest bearing life. As clearance increases, the noise, vibration, temperature rise, and load on the rolling bearing all deteriorate. Due to the presence of bearing clearance, the internal components of the bearing cannot bear the load evenly and uniformly. For example, the raceway of the stationary inner or outer ring is divided into load-bearing and non-load-bearing areas. The entire raceway working surface is borne by a localized load area, and surface spalling occurs in this area due to stress concentration. Because of the clearance, the inner and outer raceways and rollers actually bear a super-load rather than a uniform and average load, thus significantly shortening the bearing life.

[0070] For the two single-row tapered roller bearings on the gear shaft of the existing drive axle main reducer assembly, in addition to causing the aforementioned harmful effects, the clearance also significantly affects the stiffness of the gear shaft and the meshing of the driving and driven gears, making it impossible for the driving and driven gears to function properly. The existing solution is to increase the distance between the two tapered roller bearings to improve the stiffness of the gear shaft and reduce the offset of the gear shaft centerline (see...). Figure 18 and 19 Although such improvements can increase the rigidity of the gear shaft and improve the meshing state of the driving and driven gears, they still do not fundamentally solve the problem.

[0071] For the main reducer assembly with a straddle-mounted support structure, although the distance between the two single-row tapered roller bearings is very close, the clearance of these two single-row tapered roller bearings is the same as that of the cantilever bearings. The reason why the two bearings are so close is because a support guide bearing is provided near the small end of the main bevel gear (see...). Figure 15 Large clearances still seriously affect the normal operation and fatigue life of the driving and driven gears and bearings.

[0072] In summary, the clearance of the two single-row tapered roller bearings on the gear shaft of the main reducer assembly of a motor vehicle drive axle is a key factor affecting the rigidity of the main reducer assembly and the normal meshing of the driving and driven gear pairs. The only solution to ensure that the main bevel gear is in its optimal working condition is to control the clearance of the two single-row tapered roller bearings to a state of 0 to a very small positive clearance during operation.

[0073] See Figure 1 This embodiment provides a motor vehicle main reducer assembly that requires no preload and no adjustment shims, including a main bevel gear 1, a double-row bearing unit assembly 4, and a gear shaft 5.

[0074] The gear shaft 5 and the main bevel gear 1 are an integral structure.

[0075] The gear shaft 5 is equipped with a double-row bearing unit assembly 4.

[0076] The double-row bearing unit assembly 4 includes a first row of tapered roller bearings 41 and a second row of tapered roller bearings 42.

[0077] The first row of tapered roller bearings 41 is located on the side closest to the main bevel gear 1.

[0078] The first row of tapered roller bearings 41 includes an inner ring I 401, rollers I 402, and outer flanges I 404.

[0079] The second row of tapered roller bearings 42 includes an inner ring II 409, rollers II 408, and outer flanges II 406.

[0080] The first row of tapered roller bearings 41 and the second row of tapered roller bearings 42 share the same outer ring 405. The outer ring 405 is a hollow rotating body structure. The inner wall of the outer ring 405 includes outer raceway I 4051 and outer raceway II 4052.

[0081] The outer ring 405 is equipped with outer flange I 404 and outer flange II 406 at its two ends respectively. The outer flange I 404 and outer flange II 406 are respectively close to the outer raceway I 4051 and outer raceway II 4052.

[0082] The outer flange I 404, outer flange II 406, and outer ring 405 are either a single part or two parts that are attached together.

[0083] The inner ring I 401 and inner ring II 409 are assembled on the gear shaft 5.

[0084] Example 2:

[0085] The main structure of this embodiment is the same as that of embodiment 1. Furthermore, the inner ring I 401 and the inner ring II 409 are coaxially and closely assembled on the gear shaft 5.

[0086] The inner ring I 401 is a hollow rotating structure. The outer wall of the inner ring I 401 is divided into a small flange I 4011 and an inner raceway I 4012. The inner raceway I 4012 is located near the outer flange I 404. The taper of the inner raceway I 4012 is symmetrically assembled in the same direction as the taper of the outer raceway I 4051, and the two together form an annular space I. Several rollers I 402 are assembled within the annular space I.

[0087] The inner ring II 409 is a hollow rotating structure. The outer wall of the inner ring II 409 is divided into a small flange II 4091 and an inner raceway II 4092. The inner raceway II 4092 is located near the outer flange II 406. The taper of the inner raceway II 4092 is symmetrically assembled in the same direction as the taper of the outer raceway II 4052, forming an annular space II. Several rollers II 408 are assembled within the annular space II.

[0088] The end face of the small flange I4011 of the inner ring I401 and the end face of the small flange II4091 of the inner ring II409 are fitted together.

[0089] Example 3:

[0090] The main structure of this embodiment is the same as that of embodiment 2. Furthermore, the taper of the inner raceway I 4012 is greater than the taper of the inner raceway II 4092.

[0091] Example 4:

[0092] The main structure of this embodiment is the same as any one of embodiments 1 to 3. Furthermore, the inner holes of the outer flange I 404 and the outer flange II 406 are both tapered holes.

[0093] The taper of the tapered hole of the outer flange I404 is parallel to the axis of roller I402 (here, the axis refers to the center axis of roller I402 when it is assembled between the inner and outer rings).

[0094] The taper of the tapered hole of the outer flange II406 is parallel to the axis of the roller II408 (the axis here refers to the center axis of the roller II408 when it is assembled between the inner and outer rings).

[0095] Example 5:

[0096] The main structure of this embodiment is the same as any one of embodiments 1 to 4. Further, see [link to embodiment 1]. Figure 3 When the outer edge I 404 / outer edge II 406 and the outer ring 405 are an integral structure (i.e., the outer edge I 404 / outer edge II 406 and the outer ring 405 are a single part), an arc-shaped groove is provided between the end faces of the outer edge I 404 / outer edge II 406 and the outer ring 405, and the central angle corresponding to the arc-shaped groove is 270°.

[0097] Example 6:

[0098] The main structure of this embodiment is the same as any one of embodiments 1 to 5. Furthermore, when the outer retaining edge I404 adopts a split structure (i.e., the outer retaining edge I404 and the outer ring 405 are two parts), the outer retaining edge I404 is an internally hollow stepped rotating body structure, including a conical segment I4041 and a cylindrical segment I4042. The conical segment I4041 and the cylindrical segment I4042 are connected by a stepped surface I4043.

[0099] The conical section I 4041 and the outer raceway I 4051 of the outer ring 405 are in a clearance fit. The stepped surface I 4043 is in contact with the end face I of the outer ring 405. The end face I is the end closest to the outer raceway I 4051.

[0100] When the outer flange II 406 adopts a split structure (i.e., the outer flange II 406 and the outer ring 405 are two parts), the outer flange II 406 is a hollow, stepped rotating body structure, including a conical segment II 4061 and a cylindrical segment II 4062. The conical segment II 4061 and the cylindrical segment II 4062 are connected by a stepped surface II 4063.

[0101] The conical section II 4061 and the outer raceway II 4052 of the outer ring 405 are in clearance fit. The stepped surface II 4063 is in contact with the end face II of the outer ring 405. The end face II is the end closest to the outer raceway II 4052.

[0102] Example 7:

[0103] The main structure of this embodiment is the same as any one of embodiments 1 to 6. Furthermore, the outer raceway I 4051 and the outer raceway II 4052 are connected by an arc-shaped transition segment.

[0104] Example 8:

[0105] The main structure of this embodiment is the same as any one of embodiments 1 to 7. Furthermore, the contact angle of the first row of tapered roller bearings 41 is 10° to 45°. The contact angle of the second row of tapered roller bearings 42 is 0° to 44°.

[0106] Example 9:

[0107] The main structure of this embodiment is the same as any one of embodiments 1 to 8. Furthermore, the first row of tapered roller bearings 41 also includes a retainer I 403. The retainer I 403 is installed within the annular space I. A plurality of rollers I 402 are assembled within the window of the retainer I 403.

[0108] The second row of tapered roller bearings 42 also includes a retainer II 407. The retainer II 407 is installed within the annular space II. A plurality of rollers II 408 are fitted within the window of the retainer II 407.

[0109] Example 10:

[0110] The main structure of this embodiment is the same as any one of embodiments 1 to 9. Furthermore, the main reducer assembly also includes a bearing flange cover 2, a bearing seat 3, a flange 6, and a pressure plate 7.

[0111] The gear shaft 5 is assembled in the inner ring I 401 and inner ring II 409 of the double row bearing unit assembly 4. One end of the gear shaft 5 is connected to the main bevel gear 1 through the stepped surface III 101, and the other end is connected to the flange 6 through a spline (the outer circle of the gear shaft 5 away from the main bevel gear 1 is provided with an external spline, which mates with the internal spline hole of the flange 6). The flange 6, inner ring I 401 and inner ring II 409 are clamped on the gear shaft 5 by the pressure plate 7.

[0112] The small flange I4011 end of the inner ring I401 contacts the small flange II4091 end of the inner ring II409, while the inner raceway I4012 end of the inner ring I401 abuts against the stepped surface III101.

[0113] The small flange II4091 end of the inner ring II409 contacts the small flange I4011 end of the inner ring I401, while the inner raceway II4092 end of the inner ring II409 abuts against the flange 6.

[0114] The double-row bearing unit assembly 4 is assembled in the inner hole of the bearing housing 3. The inner hole of the bearing housing 3 has a stepped surface Ⅳ301.

[0115] The outer flange I 404, outer flange II 406, and outer ring 405 are axially positioned by the stepped surface IV 301, and are clamped in the inner hole of the bearing housing 3 by the flange cover 2. The bearing flange cover 2 is fastened to the side of the bearing housing 3 near the main bevel gear 1 with screws.

[0116] When the bearing flange cover 2 is fastened to the end face of the bearing housing 3 with screws, there is a certain gap between the bearing flange cover 2 and the end face of the bearing housing 3.

[0117] Example 11:

[0118] The main structure of this embodiment is the same as any one of embodiments 1 to 10. Furthermore, the main reducer assembly includes a main bevel gear 1, a bearing flange cover 2, a bearing seat 3, a double-row bearing unit assembly 4, a gear shaft 5, a flange 6, and a pressure plate 7.

[0119] See Figure 2 , Figure 3 and Figure 4The double-row bearing unit assembly 4 includes two single-row tapered roller bearings. The contact angle of the first row of tapered roller bearings 41 is 10°-45°, and the contact angle of the second row of tapered roller bearings 42 is 0°-44°.

[0120] The first row of tapered roller bearings 41 of the two single-row tapered roller bearings includes an inner ring I 401, rollers I 402, a retainer 403, and an outer flange I 404. The second row of tapered roller bearings 42 of the two single-row tapered roller bearings includes an outer flange II 406, a retainer II 407, rollers II 408, and an inner ring II 409. The first row of tapered roller bearings 41 and the second row of tapered roller bearings 42 share an outer ring 405.

[0121] See Figure 1 The main bevel gear 1 and the gear shaft 5 are a single integral part. The inner ring I 401, inner ring II 409, and flange 6 are clamped onto the gear shaft 5 by a pressure plate 7. The outer ring 405 of the double-row bearing unit assembly 4 is connected to the inner hole of the bearing housing 3. The outer ring 405, outer flange I 404, and outer flange 406 are clamped between the stepped surface IV 301 of the bearing housing 3 and the bearing flange cover 2 by the bearing flange cover 2.

[0122] Depending on the structure of various drive axles, the internal structure of the double-row bearing unit assembly 4 varies. It can be an integrated structure where the outer ring 405, outer flange I 404, and outer flange 406 are combined into a single part; or a separate structure where the outer ring 405, outer flange I 404, and outer flange 406 are three separate parts; or any one of the outer ring 405, outer flange I 404, and outer flange 406 is integrated into a single part. Without changing the function, the change to a separate structure is only for ease of implementation and to improve load-bearing capacity from a manufacturing perspective.

[0123] The technical advantages of this embodiment include good assembly performance, compact structure, light weight, large load capacity, high transmission efficiency, low temperature rise, low noise, low cost, no need for pre-tightening, no need for adjusting shims, and ultra-long fatigue life. It also offers advantages such as convenient maintenance.

[0124] Example 12:

[0125] The main structure of this embodiment is the same as any one of embodiments 1 to 11, and further includes a main bevel gear 1, a bearing flange cover 2, a bearing seat 3, a double row bearing unit assembly 4, a gear shaft 5, a flange 6, and a pressure plate 7.

[0126] The gear shaft 5 is installed in the double-row bearing unit assembly 4, and one end of the gear shaft 5 is connected to the main bevel gear 1 through the stepped surface Ⅲ101, while the other end is connected to the flange 6 through a spline and clamped by the pressure plate 7.

[0127] The double-row bearing unit assembly 4 is installed in the inner hole of the bearing housing 3.

[0128] The double-row bearing unit assembly 4 includes a first row of tapered roller bearings 41 and a second row of tapered roller bearings 42.

[0129] The first row of tapered roller bearings 41 has a contact angle of 10° to 45° and is mainly used to bear radial and axial loads, including inner ring I 401, roller I 402, bearing retainer I 403 and outer flange I 404.

[0130] The second row of tapered roller bearings 42 has a contact angle of 0° to 44° and is mainly used to bear radial loads and occasional axial loads, including inner ring II 409, roller II 408, bearing retainer II 407 and outer flange II 406.

[0131] The first row of tapered roller bearings 41 and the second row of tapered roller bearings 42 share the same outer ring 405. The outer ring 405 is a hollow rotating body structure. The inner wall of the outer ring 405 includes outer raceway I 4051 and outer raceway II 4052. The outer raceway I 4051 and outer raceway II 4052 are connected by an arc-shaped transition section.

[0132] The inner ring I 401 and inner ring II 409 are coaxially assembled on the gear shaft 5, with the larger end of the inner ring I 401 close to the side of the main bevel gear 1.

[0133] The inner ring I401 is a hollow rotating structure, and its outer side wall is divided into a small flange I4011 and an inner raceway I4012. The inner raceway I4012 is close to the main bevel gear 1 and abuts against the stepped surface III101, while the end face of the small flange I4011 is in contact with the end face of the small flange II4091 of the inner ring II409.

[0134] The taper of the inner raceway I 4012 and the taper of the outer raceway I 4051 are symmetrically assembled in the same direction, forming an annular space I. A bearing retainer I 403 is installed in the annular space I, and several rollers I 402 are assembled in the window of the bearing retainer I 403.

[0135] The inner ring II 409 is a hollow rotating structure, and its outer side wall is divided into a small flange II 4091 and an inner raceway II 4092. The inner raceway II 4092 is close to the side of the flange 6 and abuts against the small end face of the flange 6, while the end face of the small flange II 4091 is in contact with the end face of the small flange I 4011 of the inner ring I 401.

[0136] The taper of the inner raceway II 4092 and the taper of the outer raceway II 4052 are symmetrically assembled in the same direction, forming an annular space II between them. A retainer II 407 is installed in the annular space II, and several rollers II 408 are assembled in the window of the retainer II 407.

[0137] The outer flange I 404 and outer flange II 406 are rotating structures, respectively assembled in annular space I and annular space II, and in contact with the outer ring 405.

[0138] The outer flange I 404, outer flange II 406 and outer ring 5 are axially positioned by the stepped surface IV 301 of the inner hole of the bearing seat 3, and are clamped in the hole of the bearing seat 3 by the bearing flange cover 2. The bearing flange cover 2 is clamped on the end face of the bearing seat 3 near the main bevel gear 1 with screws. After the bearing flange cover 2 is fastened to the end face of the bearing seat 3 with screws, there is a certain gap between the end face of the bearing flange cover 2 and the end face of the bearing seat 3.

[0139] The outer edge I 404, outer ring 405 and outer edge II 406 are either an integral structure or a separate structure.

[0140] When the outer retaining edge I404 adopts a split structure, the outer retaining edge I404 is a hollow, stepped rotating body structure, including a conical segment I4041 and a cylindrical segment I4042. The conical segment I4041 and the cylindrical segment I4042 are connected by a stepped surface I4043.

[0141] The conical section I4041 and the outer raceway I4051 of the outer ring 405 are in clearance fit. The stepped surface I4043 is in contact with the end face I of the outer ring 405.

[0142] When the outer retaining edge II406 adopts a split structure, the outer retaining edge II406 is a hollow, stepped rotating body structure, including a conical segment II4061 and a cylindrical segment II4062. The conical segment II4061 and the cylindrical segment II4062 are connected by a stepped surface II4063.

[0143] The conical section II 4061 and the outer raceway II 4052 of the outer ring 405 are in clearance fit. The stepped surface II 4063 is in contact with the end face II of the outer ring 405.

[0144] Example 12:

[0145] The main structure of this embodiment is the same as any one of embodiments 1 to 11. Further, see [link to embodiment 1]. Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 , Figure 11 , Figure 12 and Figure 13The double-row bearing unit assembly 4 consists of two rows of tapered roller bearings. Because the main reducer assembly significantly reduces the speed of the drive shaft, the main bevel gear applies both a large radial load and a large axial load to the first row of tapered roller bearings 41 (see...). Figure 17 Therefore, the first row of tapered roller bearings 41 adopts a large contact angle design to enable it to simultaneously bear large radial and axial loads. Correspondingly, the components of the first row of tapered roller bearings 41—inner ring I 401, roller I 402, cage 403, outer flange I 404, and outer ring 405—are all large cone angle parts. The main bevel gear applies only radial loads and occasional axial loads to the second row of tapered roller bearings 42 (see...). Figure 17 Therefore, the second row of tapered roller bearings 42 adopts a small contact angle design, the purpose of which is to make the second row of tapered roller bearings 42 mainly bear radial loads. Accordingly, the various parts that make up the second row of tapered roller bearings 42, such as the outer ring 405, outer flange 406, retainer 407, roller 408, and inner ring II 409, are all small cone angle parts.

[0146] Example 13:

[0147] The main structure of this embodiment is the same as any one of embodiments 1 to 12. Furthermore, this embodiment uses an innovatively designed double-row bearing unit assembly 4 to ensure that the double-row bearing unit assembly 4 is always in a working state with 0 to a small positive clearance, thereby ensuring that the support stiffness of the main reducer assembly meets the design requirements and that the bevel gear of the main reducer assembly is in the optimal working state.

[0148] As is well known, the key parameters affecting the support stiffness of the existing main reducer assembly and the meshing of the driving and driven gear pairs are the clearance of the two single-row tapered roller bearings on the main bevel gear shaft. Although it is very easy to control the axial clearance of the two single-row tapered roller bearings on the main bevel gear shaft to be near 0 in terms of manufacturing, the contact angle of the first row tapered roller bearing 41 is about 28° (see...). Figure 16The axial load borne by the main bevel gear is entirely transferred to the first row of tapered roller bearings 41, and then from the large flange of the inner ring of the first row of tapered roller bearings 41 to the large end face of the rollers. Because there is sliding friction between the large flange of the inner ring and the large end face of the rollers, the heat generated in this area is much greater than the heat generated by rolling friction in other areas. Furthermore, since the inner ring is connected to the main bevel gear shaft through its inner bore, it transfers heat to the gear shaft. The gear shaft is located at the center of the main reducer assembly, making it difficult for the heat to dissipate. This results in a much greater temperature rise and expansion of the inner ring compared to the outer ring. To prevent the first row of tapered roller bearings 41 from seizing during operation, a sufficiently large clearance must be designed for them. The contact angle of the second row of tapered roller bearings 42 in existing main reducer assemblies is generally around 13° (see...). Figure 14 , 15 16) A portion of the radial load Q4 borne by the main bevel gear is transferred to the second row of tapered roller bearings 42. Although the second row of tapered roller bearings 42 does not bear axial load under normal operating conditions, a large derived axial load Q is generated due to the still large contact angle of 13°. 62 A large sliding friction torque is generated between the large flange of the inner ring and the large end face of the roller. According to the principle of frictional heat generation, the temperature rise of the inner ring is much higher than that of the outer ring. In order to prevent the second row of tapered roller bearings 42 from seizing, the clearance of the second row of tapered roller bearings 42 must be well controlled.

[0149] The main problem with existing main reducer assemblies is that, to ensure proper meshing of the driving and driven gear pairs, the radial runout or radial offset of the main bevel gear and gear shaft must be strictly controlled within a very small range. On the other hand, because the main reducer assembly performs the functions of reducing speed and changing the direction of torque transmission, the driven gear applies a large axial and radial force to the main bevel gear. The main bevel gear then transmits this large axial and radial force to the two single-row tapered roller bearings, causing significant friction between the inner rings and rollers of these bearings due to sliding friction. The heat generated between the outer rings and rollers of the two single-row tapered roller bearings is far less than that between the inner rings and rollers due to rolling friction. This results in a significantly greater temperature rise and expansion of the inner ring compared to the outer ring. To prevent the two single-row tapered roller bearings from seizing during operation, a sufficiently large clearance must be designed for them. However, this large clearance, in turn, reduces the rigidity of the gear shaft, making it impossible to ensure proper meshing of the driving and driven gear pairs, thus creating a vicious cycle. This contradiction has remained unresolved since the invention of the main reducer assembly. To maximize the rigidity of the gear shaft, the only solution is to increase the distance between the two single-row tapered roller bearings (see...). Figure 18 and 19Furthermore, designing the two single-row tapered roller bearings to be large enough is clearly a stopgap measure, not a fundamental solution that addresses the root cause of the problem.

[0150] This embodiment achieves the goal of making the temperature rise of the inner and outer rings and rollers almost the same through innovative bearing internal structure design (see...). Figure 17 This embodiment features several innovative designs, the most important of which are as follows: First, it integrates two existing single-row tapered roller bearings into a single double-row bearing unit assembly 4; second, it eliminates the need for adjusting shims; third, it moves the large flanges of the two existing single-row tapered roller bearings from the inner ring to the two end faces of the outer ring of the double-row bearing unit assembly 4; fourth, it designs a clearance fit between the conical surface I4041 of the outer flange and the outer raceway I4051 of the outer ring 405; and fifth, based on the different loads borne by the two single-row tapered roller bearings in the double-row bearing unit assembly 4, it designs the two single-row tapered roller bearings into an asymmetrical structure to improve transmission efficiency and reduce temperature rise.

[0151] In this embodiment, the first row of tapered roller bearings 41 in the double-row bearing unit assembly 4 still adopts a large contact angle design (see...). Figure 17 , 20 As analyzed above, the main bevel gear 1 applies a large radial and axial load to the inner ring I401 of the first row of tapered roller bearings 41. The inner ring I401 transfers the load to the roller I402, which in turn transfers it to the outer raceway I4051 and outer flange I404 of the outer ring 5. A huge axial load is generated between the large end face of the roller I402 and the working surface of the outer flange I404. Due to sliding friction, a large amount of heat is generated on the outer flange I404 and the roller I402. Correspondingly, due to the friction between the inner raceway I4012 of the roller I402 and the outer raceway I4051 of the inner ring I401, the outer raceway I4051 of the outer ring 405... The heat generated by rolling friction between rollers I 402 and outer flange I 404 is far less than the heat generated by sliding friction. Since both rollers I 402 and outer flange I 404 are in contact with the outer ring 405, heat is easily transferred to the outer ring 405. The outer ring 405 is installed inside the inner hole of the bearing housing 3. The area of ​​the outer circle of the outer ring 405 is about twice the area of ​​the inner hole of the inner rings I 401 and II 409. The heat dissipation effect of the outer ring 405 through the bearing housing 3 is much better than that of the inner rings I 401 and II 409, making it easy for the heat on rollers I 402 and outer flange I 404 to be transferred away through the outer ring 405 and the bearing housing 3. In addition, this embodiment adopts an innovative design for the outer flange I 404 (see... Figure 13 The dimensions of the conical surface I4041 of the outer flange I404 are designed to be approximately 0.2 mm smaller than the dimensions of the outer raceway I4051 of the outer ring 405, creating a certain gap between the conical surface I4041 of the outer flange I404 and the outer raceway I4051 of the outer ring 405 (see...). Figure 20 In this way, even if the outer flange I404 expands significantly due to temperature rise, it only reduces the gap between the conical surface I4011 of the outer flange I404 and the outer raceway I4051 of the outer ring 405. When the main reducer assembly stops working, the outer flange I404 shrinks back to its original size. That is, the expansion and contraction of the outer flange I404 has no effect on the bearing clearance.

[0152] In addition, since the double row bearing unit assembly 4 uses gear oil for lubrication and cooling, some of the heat generated by its internal components is also carried away by the lubricating oil.

[0153] As the preceding analysis shows, although the temperature rise of the outer ring 405, roller I 402, and outer flange I 404 is much greater than that of the inner ring, through innovative design, most of the heat generated by these three parts is transferred to the air through the bearing housing 3. The outer flange I 404 is a thin-walled part with a small height; although the heat generated on its working surface cannot be completely dissipated at once, causing the outer flange I 404 to expand, this expansion does not affect the clearance change. In summary, through the above innovative design, the temperature rise of all parts of the first row of tapered roller bearings 41 is basically the same during operation, and the clearance of the first row of tapered roller bearings 41 remains basically unchanged. Even if there are slight variations, they are only slightly larger, having almost no impact on the support stiffness of the main reducer assembly and the meshing of the driving and driven gear pairs.

[0154] Another innovative design of this embodiment is that, based on the characteristic that the second row of tapered roller bearings 42 in the double-row bearing unit assembly 4 only bears pure radial loads and occasional axial loads, a very small contact angle design is adopted (see...). Figure 17 When the main bevel gear 1 transmits a portion of the radial load Q4 to the second row of tapered roller bearings 42, the contact angle of the second row of tapered roller bearings 42 is very small, and the derived axial load generated by the pure radial load is also very small. Therefore, the sliding friction between the working surface of the outer flange II 406 and the large end face of the roller II 408 is very small, and the heat generated is very small. Since the outer ring 405 is installed inside the inner hole of the bearing housing 3, the heat generated by both sliding friction and rolling friction inside the second row of tapered roller bearings 42 is very small and can be easily transferred out through the outer ring 405, so that the temperature rise of the inner and outer rings of the second row of tapered roller bearings 42 is basically the same.

[0155] In summary, the design of the double-row bearing unit assembly 4 in this embodiment takes into account the sliding friction between the outer flange I 404 and the roller I 402, resulting in greater heat generation from the outer flange I 404, outer ring 405, and roller I 402 compared to the inner ring. However, since the heat dissipation of the outer ring is better than that of the inner ring, with an appropriate contact angle, it can be ensured that all parts of the entire double-row bearing unit assembly 4 have essentially the same temperature rise. The clearance of the double-row bearing unit assembly 4 during operation can be controlled at the level of the main reducer assembly at the factory, that is, between 0 and a very small positive clearance, with the gear offset δ1 (or δ2) approximately equal to 0 (see...). Figure 18 and 19 The support stiffness of the main reducer assembly meets the design requirements, and the main and driven gear pairs are in the optimal meshing state.

[0156] Example 14:

[0157] The main structure of this embodiment is the same as any one of embodiments 1 to 13. Furthermore, since the axial clearance of the double-row bearing unit assembly 4 is almost zero during operation, it not only meets the design requirements for the support stiffness of the main reducer assembly, ensuring the optimal meshing state of the driving and driven gear pairs, but also significantly improves the fatigue life of the double-row bearing unit assembly 4 and the driving and driven gears. Simultaneously, due to the significant reduction in the contact angle of the second-row tapered roller bearing 42, the derived axial load generated by the second-row tapered roller bearing 42 under pure radial load is reduced to almost zero. Therefore, the transmission efficiency of the main reducer assembly is improved, the energy consumption of the main reducer assembly is reduced, and the temperature rise of the main reducer assembly is reduced. Because the bearings and gears inside the main reducer assembly are in optimal working condition and the heat generation is at its lowest, the gear oil life can be maintained at its maximum, extending the maintenance time of the entire main reducer assembly and reducing maintenance costs.

[0158] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A motor vehicle main reducer assembly that requires no preload and no adjustment shims, characterized in that: It includes a main bevel gear (1), a double-row bearing unit assembly (4), and a gear shaft (5); The gear shaft (5) and the main bevel gear (1) are an integral structure; The gear shaft (5) is equipped with a double row bearing unit assembly (4); The double-row bearing unit assembly (4) includes a first row of tapered roller bearings (41) and a second row of tapered roller bearings (42); The first row of tapered roller bearings (41) is located on the side closest to the main bevel gear (1); The first row of tapered roller bearings (41) includes an inner ring I (401), rollers I (402) and outer flanges I (404); The second row of tapered roller bearings (42) includes an inner ring II (409), rollers II (408) and an outer flange II (406); The first row of tapered roller bearings (41) and the second row of tapered roller bearings (42) share the same outer ring (405); the outer ring (405) is a hollow rotating body structure; the inner wall of the outer ring (405) includes outer raceway I (4051) and outer raceway II (4052); The outer ring (405) is equipped with outer flange I (404) and outer flange II (406) at both ends respectively; the outer flange I (404) and outer flange II (406) are respectively close to the outer raceway I (4051) and outer raceway II (4052); The outer flange I (404) / outer flange II (406) and the outer ring (405) are either a single part or two parts that are attached together. The inner ring I (401) and inner ring II (409) are assembled on the gear shaft (5).

2. The motor vehicle main reducer assembly that requires no preload and no adjustment shims as described in claim 1, characterized in that: The inner ring I (401) and inner ring II (409) are coaxially and closely assembled on the gear shaft (5); The inner ring I (401) is a hollow rotating structure; the outer wall of the inner ring I (401) is divided into a small flange I (4011) and an inner raceway I (4012); the inner raceway I (4012) is located near the outer flange I (404); the taper of the inner raceway I (4012) and the taper of the outer raceway I (4051) are symmetrically assembled in the same direction, and the two together form an annular space I; a number of rollers I (402) are assembled in the annular space I. The inner ring II (409) is a hollow rotating structure; the outer side wall of the inner ring II (409) is divided into a small flange II (4091) and an inner raceway II (4092); the inner raceway II (4092) is located near the outer flange II (406); the taper of the inner raceway II (4092) and the taper of the outer raceway II (4052) are symmetrically assembled in the same direction, and the two together form an annular space II; a number of rollers II (408) are assembled in the annular space II. The end face of the small flange I (4011) of the inner ring I (401) and the end face of the small flange II (4091) of the inner ring II (409) are fitted together.

3. The motor vehicle main reducer assembly that requires no preload and no adjustment shims as described in claim 2, characterized in that: The taper of inner raceway I (4012) is greater than that of inner raceway II (4092).

4. The motor vehicle main reducer assembly that requires no preload and no adjustment shims as described in claim 1, characterized in that: The inner holes of the outer flange I (404) and the outer flange II (406) are both tapered holes; The taper of the tapered hole of the outer flange I (404) is parallel to the axis of roller I (402); the taper of the tapered hole of the outer flange II (406) is parallel to the axis of roller II (408).

5. A motor vehicle main reducer assembly that requires no preload and no adjustment shims as described in claim 1, characterized in that: When the outer edge I (404) / outer edge II (406) and the outer ring (405) are an integral structure, an arc-shaped groove is provided between the end faces of the outer edge I (404) / outer edge II (406) and the outer ring (405), and the central angle corresponding to the arc-shaped groove is 270°.

6. A motor vehicle main reducer assembly that requires no preload and no adjustment shims as described in claim 1, characterized in that: When the outer edge I (404) adopts a split structure, the outer edge I (404) is a hollow stepped rotating body structure, including a conical segment I (4041) and a cylindrical segment I (4042); the conical segment I (4041) and the cylindrical segment I (4042) are connected by a stepped surface I (4043); The conical segment I (4041) and the outer raceway I (4051) of the outer ring (405) are in clearance fit; the stepped surface I (4043) is in contact with the end face I of the outer ring (405); the end face I is the end closest to the outer raceway I (4051); When the outer edge II (406) adopts a split structure, the outer edge II (406) is a hollow stepped rotating body structure, including a conical segment II (4061) and a cylindrical segment II (4062); the conical segment II (4061) and the cylindrical segment II (4062) are connected by a stepped surface II (4063); The conical segment II (4061) and the outer raceway II (4052) of the outer ring (405) are in clearance fit; the stepped surface II (4063) is in contact with the end face II of the outer ring (405); the end face II is the end closest to the outer raceway II (4052).

7. A motor vehicle main reducer assembly that requires no preload and no adjustment shims as described in claim 1, characterized in that: The outer raceway I (4051) and outer raceway II (4052) are connected by an arc-shaped transition section.

8. A motor vehicle main reducer assembly that requires no preload and no adjustment shims as described in claim 1, characterized in that: The contact angle of the first row of tapered roller bearings (41) is 10° to 45°; the contact angle of the second row of tapered roller bearings (42) is 0° to 44°.

9. A motor vehicle main reducer assembly that requires no preload and no adjustment shims according to claim 2, characterized in that: The first row of tapered roller bearings (41) further includes a retainer I (403); the retainer I (403) is installed in an annular space I; a plurality of rollers I (402) are assembled in the window of the retainer I (403); The second row of tapered roller bearings (42) also includes a retainer II (407); the retainer II (407) is installed in an annular space II; and a plurality of rollers II (408) are assembled in the window of the retainer II (407).

10. A motor vehicle main reducer assembly that requires no preload and no adjustment shims according to claim 2, characterized in that: The main reducer assembly also includes a bearing flange cover (2), a bearing housing (3), a flange (6), and the pressure plate (7); The gear shaft (5) is assembled in the inner ring I (401) and inner ring II (409) of the double row bearing unit assembly (4), and one end of the gear shaft (5) is connected to the main bevel gear (1) through the stepped surface III (101), and the other end is connected to the flange (6) through the spline. The flange (6), inner ring I (401) and inner ring II (409) are clamped on the gear shaft (5) by the pressure plate (7). The small side I (4011) end of the inner ring I (401) contacts the small side II (4091) end of the inner ring II (409), while the inner raceway I (4012) end of the inner ring I (401) abuts against the step surface III (101). The small flange II (4091) end of the inner ring II (409) contacts the small flange I (4011) end of the inner ring I (401), while the inner raceway II (4092) end of the inner ring II (409) abuts against the flange (6). The double-row bearing unit assembly (4) is assembled in the inner hole of the bearing housing (3); The outer flange I (404), outer flange II (406) and outer ring (405) are axially positioned by the stepped surface IV (301), and the outer flange I (404), outer flange II (406) and outer ring (405) are clamped in the inner hole of the bearing seat (3) by the flange cover (2); the bearing flange cover (2) is fastened to the side of the bearing seat (8) near the main bevel gear (1) with screws.

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