A rear axle lightweight fixed universal joint

Abstract

The application relates to the field of automobile transmission technology, and particularly discloses a rear axle lightweight fixed type universal joint, which comprises an outer ball cage and a star-shaped sleeve, a retainer is arranged in the outer ball cage, a plurality of steel balls are arranged between the outer ball cage and the star-shaped sleeve, a plurality of windows for restraining the steel balls are arranged on the retainer in an equidistant manner, the star-shaped sleeve is rotationally assembled in the outer ball cage through the retainer and the steel balls, and the inner wall of the outer ball cage is provided with an inner spherical surface. In the application, the steel balls between the outer ball channel one and the inner ball channel one are constrained at the spatial intersection points of the trajectory lines between the two, the steel balls between the inner ball channel two and the outer ball channel two are constrained at the spatial intersection points of the trajectory lines between the two, the moving trajectories of the steel balls are constrained through the cooperation of the first type ball channel and the second type ball channel, the working angle of the universal joint is adjusted, and the lightweight is realized while meeting the rear axle steering requirements.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of automobile transmission technology, in particular to a rear axle lightweight fixed universal joint. BACKGROUND

[0002] Traditional fuel vehicles are dominated by front-wheel drive structure due to engine layout and transmission system complexity. New energy vehicles completely break through the technical barrier by replacing the engine, gearbox, transmission shaft and fuel tank with a three-electricity system (motor / electronic control / battery). Industry data shows that rear-wheel drive accounts for more than 70% of pure electric vehicles priced above 150,000 yuan, becoming the mainstream choice in the mid-to-high-end market.

[0003] In the existing technology, when fixed slip cross ball track + end slip cross universal joint is used, the defect is that the maximum swing angle is 22 degrees, which cannot meet the market requirement of rear-wheel drive steering of 30 degrees. When ordinary large-angle fixed universal joint + three-ball pin movable universal joint is used for rear-wheel drive steering, the defect is that the weight is large and the transmission efficiency is low, which cannot meet the requirements of lightweight and high efficiency in the existing market.

[0004] Therefore, the defects of the existing technical solutions are as follows:

[0005] 1. The fixed slip cross ball track + end slip cross universal joint structure cannot meet the rear-wheel drive steering rigidity standard, i.e., the working swing angle is greater than 30 degrees.

[0006] 2. The overall weight of the fixed universal joint + three-ball pin movable universal joint structure is heavy, which cannot meet the demand for range and energy efficiency improvement.

[0007] 3. The power transmission efficiency of the ordinary large-angle universal joint structure is low, which is not suitable for high-torque motors.

[0008] Therefore, we propose a rear axle lightweight fixed universal joint. SUMMARY

[0009] The present application provides a rear axle lightweight fixed universal joint, which has the beneficial effects of being applicable to rear axle steering structure, lightweight, small internal friction, and high NVH performance, solving the problems mentioned in the above background technology.

[0010] The application provides the following technical scheme: a rear axle lightweight fixed universal joint, comprising an outer cage and a star-shaped sleeve, a retainer is arranged in the outer cage, a plurality of steel balls are arranged between the outer cage and the star-shaped sleeve, a plurality of windows for restraining the steel balls are arranged on the retainer in an equidistant manner, the star-shaped sleeve is rotationally assembled in the outer cage through the retainer and the steel balls, an inner spherical surface is arranged on the inner wall of the outer cage, cage ball channels are arranged on the outer cage in a central symmetric manner along the inner spherical surface, an outer spherical surface is arranged on the outer wall of the star-shaped sleeve, star sleeve ball channels are arranged on the star-shaped sleeve in a central symmetric manner along the outer spherical surface, and the cage ball channels and the star sleeve ball channels cooperate to restrain the movement track of the steel balls; the cage ball channels and the star sleeve ball channels are combined to form a first type of raceway and a second type of raceway for restraining the movement track of the steel balls.

[0011] As a preferred scheme of the application, the cage ball channels comprise an inner channel one and an inner channel two, the inner channel one and the inner channel two are alternately distributed along the inner spherical surface in sequence, the center point of the inner channel one is located on the right side of the center line of the inner spherical surface, and the center point of the inner channel two is located on the left side of the center line of the inner spherical surface; the star sleeve ball channels comprise an outer channel one and an outer channel two, the outer channel one and the outer channel two are alternately distributed along the outer spherical surface in sequence, the center point of the outer channel one is located on the left side of the center line of the outer spherical surface, and the center point of the outer channel two is located on the right side of the center line of the outer spherical surface; the first type of raceway is formed by the combination of the inner channel one and the outer channel one; and the second type of raceway is formed by the combination of the inner channel two and the outer channel two.

[0012] As a preferred scheme of the application, the maximum rotation angle of the star-shaped sleeve in the outer cage through the steel ball is 32°, and the track line of the steel ball moving along the inner channel one, the outer channel one, the inner channel two and the outer channel two is in a circular arc shape. 32°, the track line of the steel ball moving along the inner channel one, the outer channel one, the inner channel two and the outer channel two is in a circular arc shape.

[0013] As a preferred scheme of the application, the inner channel one and the inner channel two are alternately arranged in four groups along the inner spherical surface, and the outer channel one and the outer channel two are alternately arranged in four groups along the outer spherical surface; and eight steel balls are equidistantly distributed along the center line of the retainer.

[0014] As a preferred scheme of the application, the inner channel one and the inner channel two on the outer cage are each provided with a riveting structure for riveting the steel ball, the riveting structure is located at the outermost side of the inner channel one and the inner channel two, and the steel ball can move along the inner channel one and the inner channel two raceways to the maximum extent.

[0015] As a preferred scheme of the application, the retainer is gap-fitted with the inner spherical surface, and the gap size is 0.01-0.5 mm.

[0016] As a preferred scheme of the present application, the center points of the outer ball cage, the retainer and the star-shaped sleeve coincide with each other, and the center lines of the inner spherical surface and the outer spherical surface in the initial state coincide with each other.

[0017] As a preferred scheme of the present application, the angle between the central axis of the star-shaped sleeve and the central axis of the outer ball cage is , and the angle between the central axis of the retainer and the central axis of the outer ball cage is , wherein .

[0018] As a preferred scheme of the present application, the included angle between the tangent of the contact surface of the inner ball track and the tangent of the contact surface of the outer ball track is the opening angle ai, and the included angle between the tangent of the contact surface of the inner ball track and the tangent of the contact surface of the outer ball track is ao, wherein the opening angle ai = the opening angle ao = 14°, and the directions of the opening angle ai and the opening angle ao are opposite.

[0019] The present application has the following advantages:

[0020] 1. In the scheme, the opening angles ai and ao of the inner ball tracks of the outer ball cage and the star-shaped sleeve are equal in angle and opposite in direction, so that the axial component force of the steel ball acting on the contact surface of the window of the retainer can be offset, thereby reducing the axial load and the stress generated thereby that the retainer bears under high working swing angle, which significantly enhances the structural strength and anti-deformation ability of the retainer, and effectively prevents plastic deformation of the retainer due to excessive axial force under the limit working condition close to or reaching the maximum design swing angle.

[0021] 2. In the scheme, by increasing the fitting gap between the inner spherical surface and the outer spherical surface, more lubricating oil can enter the contact area, a more uniform oil film can be formed, dry friction between the retainer and the outer ball cage can be reduced, wear can be reduced, and transmission efficiency can be improved. Moreover, as a guide, if the outer circle is too tight, it will produce "jumping" rotation when the steel ball deflects. After loosening the gap, the retainer can fine-tune its posture under the action of the corner, so that the rolling track of the steel ball is smoother.

[0022] 3. In the scheme, the steel ball between the outer raceway one and the inner raceway one is constrained at the spatial intersection of the track line between the inner raceway one and the outer raceway one, the steel ball between the inner raceway two and the outer raceway two is constrained at the spatial intersection of the track line between the inner raceway two and the outer raceway two, the movement track of the steel ball is constrained through the cooperation of the first type raceway and the second type raceway, so as to adjust the working angle of the universal joint, so that the universal joint meets the rear axle steering requirement, and the problem of affecting transmission caused by too large angle is avoided.

[0023] 4. In the scheme, the steel ball is riveted at the raceway opening of the inner raceway one, and the riveting point of the opening is used to limit the position of the limit swing angle of the steel ball, so as to avoid the steel ball from being out of place. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a top view structural schematic diagram of a rear axle lightweight fixed universal joint in the application;

[0025] Figure 2 It is an exploded view of a rear axle lightweight fixed universal joint in the application;

[0026] Figure 3 It is a top view structural schematic diagram of a star-shaped sleeve in the application;

[0027] Figure 4 It is a bottom view structural schematic diagram of a star-shaped sleeve in the application;

[0028] Figure 5 It is a three-dimensional structural schematic diagram of a retainer in the application;

[0029] Figure 6 It is a position schematic diagram of a riveting point in the riveting structure in the application;

[0030] Figure 7 It is a raceway track schematic diagram of the inner raceway one and the inner raceway two in the application;

[0031] Figure 8 It is a raceway track schematic diagram of the outer raceway one and the outer raceway two in the application;

[0032] Figure 9 It is a raceway track schematic diagram of the first type raceway composed of the inner raceway one and the outer raceway one in the application;

[0033] Figure 10 It is a raceway track schematic diagram of the second type raceway composed of the inner raceway two and the outer raceway two in the application;

[0034] Figure 11 It is a schematic diagram of the maximum working swing angle of the star-shaped sleeve in the outer cage in the application;

[0035] Figure 12The schematic diagram of the opening angle between the inner raceway one and the outer raceway one in the application;

[0036] Figure 13 The schematic diagram of the opening angle between the inner raceway two and the outer raceway two in the application.

[0037] In the figure: 1, outer cage; 10, cage raceway; 11, inner surface; 100, inner raceway one; 110, inner raceway two; 2, retainer; 20, window; 3, star sleeve; 30, star sleeve raceway; 31, outer surface; 300, outer raceway one; 310, outer raceway two; 4, steel ball; 5, knuckle center. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the application.

[0039] As Figures 1-13 shown, the application provides a rear axle lightweight fixed universal joint, which comprises an outer cage 1 and a star sleeve 3. The outer cage 1 is internally provided with a retainer 2. A plurality of steel balls 4 are arranged between the outer cage 1 and the star sleeve 3. A plurality of windows 20 for constraining the steel balls 4 are equidistantly arranged on the retainer 2. The star sleeve 3 is rotationally assembled in the outer cage 1 through the retainer 2 and the steel balls 4. An inner surface 11 is arranged on the inner wall of the outer cage 1. Cage raceways 10 are centrally and symmetrically arranged on the outer cage 1 along the inner surface 11. An outer surface 31 is arranged on the outer wall of the star sleeve 3. Star sleeve raceways 30 are centrally and symmetrically arranged on the star sleeve 3 along the outer surface 31. The cage raceways 10 and the star sleeve raceways 30 cooperate to constrain the movement track of the steel balls 4. The maximum rotation angle of the star sleeve 3 in the outer cage 1 is 32° through the steel balls 4. The cage raceways 10 and the star sleeve raceways 30 combine to form a first type of raceway and a second type of raceway for constraining the movement track of the steel balls 4. The plurality of steel balls 4 respectively move along the first type of raceway and the second type of raceway composed of the cage raceways 10 and the star sleeve raceways 30 in an arc shape.

[0040] Reference Figures 1-10, the center points of the outer ball cage 1, the retainer 2 and the star-shaped sleeve 3 coincide with each other, and the coinciding position is the center of the spline type 5, the ball cage channel 10 includes an inner channel one 100 and an inner channel two 110, the inner channel one 100 and the inner channel two 110 are alternately distributed along the inner spherical surface 11, the star sleeve channel 30 includes an outer channel one 300 and an outer channel two 310, the outer channel one 300 and the outer channel two 310 are alternately distributed along the outer spherical surface 31, wherein the center point of the inner channel one 100 is located on the right side of the center line of the inner spherical surface 11, the center point of the inner channel two 110 is located on the left side of the center line of the inner spherical surface 11, the center point of the outer channel one 300 is located on the left side of the center line of the outer spherical surface 31, and the center point of the outer channel two 310 is located on the right side of the center line of the outer spherical surface 31; the constraint scheme of the steel ball 4 is specifically that the channel center axis of the inner channel one 100 is located on a straight line parallel to the central axis of the outer ball cage 1 and axially offset to the right side of the center of the spline type 5 by a distance, the channel center axis of the outer channel one 300 is located on a straight line parallel to the central axis of the star-shaped sleeve 3 and axially offset to the left side of the center of the spline type 5 by a distance, the outer channel one 300 and the inner channel one 100 combine to form a first type of rolling channel, and the steel ball 4 located between the outer channel one 300 and the inner channel one 100 is constrained at the spatial intersection point of the trajectory line between the inner channel one 100 and the outer channel one 300; the channel center axis of the inner channel two 110 is located on a straight line parallel to the central axis of the outer ball cage 1 and axially offset to the left side of the center of the spline type 5 by a distance, the channel center axis of the outer channel two 310 is located on a straight line parallel to the central axis of the star-shaped sleeve 3 and axially offset to the right side of the center of the spline type 5 by a distance, the inner channel two 110 and the outer channel two 310 combine to form a second type of rolling channel, and the steel ball 4 located between the inner channel two 110 and the outer channel two 310 is constrained at the spatial intersection point of the trajectory line between the inner channel two 110 and the outer channel two 310; that is, the movement trajectory of the steel ball 4 is constrained by the cooperation of the first type of channel and the second type of channel, so that the maximum rotation angle of the star-shaped sleeve 3 in the outer ball cage 1 does not exceed 32°, so that the universal joint structure can meet the working swing angle requirement of the rear axle in the rear drive steering. 32°, thereby enabling the universal joint structure to meet the working swing angle requirement of the rear axle in the rear drive steering.

[0041] In the embodiment, the inner channel one 100 and the inner channel two 110 are alternately provided with four groups along the circumference of the inner spherical surface 11, the outer channel one 300 and the outer channel two 310 are alternately provided with four groups along the circumference of the outer spherical surface 31 on the outer wall of the star-shaped sleeve 3; the steel balls 4 are equally spaced and distributed along the center line of the retainer 2, and there are eight steel balls 4, and the working angle between the star-shaped sleeve 3, the retainer 2 and the outer ball cage 1 is ​32°, so the trajectory variation of the steel ball 4 and the range of the cage 2 to keep the steel ball 4 are reduced, so the thickness of the cage 2 can be reduced to meet the requirement of light weight, and the wrapping degree of the steel ball 4 by the raceway 1 composed of the inner raceway 100 and the outer raceway 300 and the raceway 2 composed of the inner raceway 110 and the outer raceway 310 is improved, so the design value of the pressure angle is indirectly improved to improve the load capacity of the raceway and reduce the positioning diameter of the raceway, and because the effective swing angle of the cage 2, the star sleeve 3 and the outer cage 1 is reduced, the effective use range is reduced, so the use wear is reduced and the service life is improved under the condition of meeting the requirement of weight reduction.

[0042] Reference Figure 1 , Figure 12 and Figure 13 The included angle between the tangent of the contact surface of the inner raceway 100 and the tangent of the contact surface of the outer raceway 300 is the opening angle αi, and the included angle between the tangent of the contact surface of the inner raceway 110 and the tangent of the contact surface of the outer raceway 310 is αo, wherein the opening angle αi=the opening angle αo=14°, and the directions of the opening angles αi and αo are opposite, the opposite opening angles can offset the axial component force of the steel ball 4 passing through the window 20 of the cage 2, the balance of the axial force greatly reduces the axial load and the stress generated thereby borne by the cage 2 under high working swing angle, which significantly enhances the structural strength and deformation resistance of the cage 2, and effectively prevents the cage 2 from plastic deformation due to excessive axial force, especially in the limit working condition close to or reaching the maximum design swing angle.

[0043] Reference Figures 7-10, the trajectory lines of the steel ball moving along the inner raceway one 100, the outer raceway one 300, the inner raceway two 110 and the outer raceway two 310 are circular arcs, the center lines of the inner spherical surface 11 and the outer spherical surface 31 coincide with each other in the initial state, the trajectory line of the steel ball 4 moving along the inner raceway one 100 is a circular arc which offsets a distance to the right of the center line of the inner spherical surface 11, the radius of the circular arc is R1, the trajectory line of the steel ball 4 moving along the outer raceway one 300 is a circular arc which offsets a distance to the left of the center line of the outer spherical surface 31, the radius of the circular arc is R2, the trajectory line of the steel ball 4 moving along the inner raceway two 110 is a circular arc which offsets a distance to the left of the center line of the inner spherical surface 11, the radius of the circular arc is R3, the trajectory line of the steel ball 4 moving along the outer raceway two 310 is a circular arc which offsets a distance to the right of the center line of the outer spherical surface 31, the radius of the circular arc is R4, wherein the center points of R1 and R3 are located to the right of the nodal center 5, the center points of R2 and R4 are located to the left of the nodal center 5, the offset distances between the center lines of the inner raceway one 100, the inner raceway two 110, the outer raceway one 300 and the outer raceway two 310 and the center line of the outer spherical surface 31 are e, the distances from the center of the steel ball to the inner raceway one 100, the inner raceway two 110, the outer raceway one 300 and the outer raceway two 310 are PCR, then e = PCR*sin (α0 / 2) needs to be met, wherein α0 is the raceway opening angle, since α0 = αi, the offset distances of the center lines of the inner raceway one 100, the inner raceway two 110, the outer raceway one 300 and the outer raceway two 310 to the left and right sides of the center line of the outer spherical surface 31 are equal.

[0044] It should be noted that the circular arcs formed by the trajectory lines of the steel ball moving along the inner raceway one 100, the inner raceway two 110, the outer raceway one 300 and the outer raceway two 310 have their centers offset from the center line axis of the inner spherical surface 11, so that the two raceways respectively constrain the moving trajectory of the steel ball 4, and therefore the moving trajectory of the steel ball 4 can be constrained by setting raceways with different angles to limit the swing amplitude of the star-shaped sleeve 3 in the outer cage 1, so as to achieve the purpose of adjusting the maximum swing angle of the star-shaped sleeve 3. Therefore, in addition to the above-mentioned scheme, the cage raceway 10 with uniform center points and the star sleeve raceway 30 with uniform center points can also be used, and at this time the center points of the cage raceway 10 and the star sleeve raceway 30 are in central symmetry, which can also constrain the moving trajectory of the steel ball 4 to achieve the same purpose.

[0045] Reference Figures 1-13, the retainer 2 is in clearance fit with the inner spherical surface 11, and the clearance is 0.01-0.5mm, the clearance fit of the retainer 2 and the inner spherical surface 11 can facilitate the penetration of lubricating oil, thereby reducing the jerk generated during use, and improving the NVH performance, in the embodiment, the clearance between the side wall of the retainer 2 and the outer wall of the inner spherical surface 11 is 0.3 microns, which allows more grease to enter the contact area, and a more uniform oil film can be formed, reducing dry friction between the retainer 2 and the outer spherical cage 1, reducing wear and improving transmission efficiency, and the retainer 2 acts as a guide, if the outer circle is too tight, it will produce "jumping" rotation when the steel ball 4 deflects, after loosening the clearance, the retainer 2 can fine-tune its posture under the action of the corner, making the rolling track of the steel ball 4 smoother.

[0046] Reference Figure 1 and Figure 11 , the angle formed between the central axis of the star-shaped sleeve 3 and the central axis of the outer spherical cage 1 is , the angle formed between the central axis of the retainer 2 and the central axis of the outer spherical cage 1 is , wherein , when the swing amplitude of the star-shaped sleeve 3 is in the initial state, , are all 0°, when the swing amplitude of the star-shaped sleeve 3 is in the maximum limit angle, the angle formed between the central axis of the star-shaped sleeve 3 and the central axis of the outer spherical cage 1 is 32°, at this time, , the steel ball 4 is constrained by the rolling track one formed by the inner raceway one 100 and the outer raceway one 300 and the rolling track two formed by the inner raceway two 110 and the outer raceway two 310, the four steel balls 4 in the four rolling tracks one interact with the four steel balls 4 in the four rolling tracks two, and maintain a balanced state.

[0047] Reference Figure 6 , the inner raceway one 100 and the inner raceway two 110 on the outer spherical cage 1 are provided with riveting structures for riveting the steel ball 4, the riveting structures are located at the outermost side of the inner raceway one 100 and the inner raceway two 110, and the steel ball 4 can move along the inner raceway one 100 and the inner raceway two 110 rolling track to the maximum, because the working angle is reduced, the rear axle lightweight fixed type universal joint needs to be placed in the limit position, and the star-shaped sleeve 3, the outer spherical cage 1 and the retainer 2 cannot stably limit the steel ball 4, resulting in the risk of the steel ball 4 being pulled out under the limit torque, so the riveting is performed at the raceway opening part of the inner raceway one 100, and the limit swing angle position of the steel ball 4 is limited by the riveting points of the opening part, to avoid the steel ball 4 from being pulled out.

[0048] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting; it is not intended to be used to limit the scope of the present application. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this application belongs. The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

Claims

1. A lightweight fixed universal joint for rear axle, comprising an outer ball cage (1) and a star-shaped sleeve (3), wherein a retainer (2) is provided inside the outer ball cage (1), and a plurality of steel balls (4) are provided between the outer ball cage (1) and the star-shaped sleeve (3), and a plurality of windows (20) for constraining the steel balls (4) are provided equidistantly on the retainer (2), and the star-shaped sleeve (3) is rotatably assembled inside the outer ball cage (1) through the retainer (2) and the steel balls (4), characterized in that: The inner wall of the outer ball cage (1) is provided with an inner spherical surface (11). The outer ball cage (1) is provided with a ball cage track (10) in a centrally symmetrical manner along the inner spherical surface (11). The outer wall of the star-shaped sleeve (3) is provided with an outer spherical surface (31). The star-shaped sleeve (3) is provided with a star-shaped track (30) in a centrally symmetrical manner along the outer spherical surface (31). The ball cage track (10) and the star-shaped track (30) cooperate to constrain the movement trajectory of the steel ball (4). The ball cage track (10) and the star-shaped track (30) are combined to form a first type of track and a second type of track for constraining the movement trajectory of the steel ball (4). The ball cage fairway (10) includes inner fairway one (100) and inner fairway two (110), which are alternately distributed along the inner spherical surface (11). The center point of inner fairway one (100) is located to the right of the center line of the inner spherical surface (11), and the center point of inner fairway two (110) is located to the left of the center line of the inner spherical surface (11). The star-shaped fairway (30) includes outer fairway one (300) and outer fairway two (310), which are alternately distributed along the outer spherical surface (31). The center point of outer fairway one (300) is located to the left of the center line of the outer spherical surface (31), and the center point of outer fairway two (310) is located to the right of the center line of the outer spherical surface (31). The first type of raceway is formed by combining the inner raceway one (100) and the outer raceway one (300); the second type of raceway is formed by combining the inner raceway two (110) and the outer raceway two (310). The angle formed between the tangent of the inner ball track one (100) and the contact surface of the steel ball (4) and the tangent of the outer ball track one (300) and the contact surface of the steel ball (4) is the opening angle αi, and the angle formed between the tangent of the inner ball track two (110) and the contact surface of the steel ball (4) and the tangent of the outer ball track two (310) and the contact surface of the steel ball (4) is αo.

2. The lightweight fixed universal joint for rear axles according to claim 1, characterized in that: The center points of the outer ball cage (1), the cage (2) and the star sleeve (3) coincide with each other, and the point of coincidence is the segment center (5). In the initial state, the center lines of the inner spherical surface (11) and the outer spherical surface (31) coincide with each other.

3. A lightweight fixed universal joint for rear axles according to claim 2, characterized in that: The star-shaped sleeve (3) rotates within the outer ball cage (1) by a maximum angle of ±32° via the steel ball (4).

4. A lightweight fixed universal joint for rear axles according to claim 2, characterized in that: The angle formed between the central axis of the star-shaped sleeve (3) and the central axis of the outer ball cage (1) is... The angle formed between the central axis of the cage (2) and the central axis of the outer ball cage (1) is... ,in, .

5. A lightweight fixed universal joint for rear axles according to claim 1, characterized in that: The retainer (2) is fitted with the inner spherical surface (11) with a clearance of 0.01 to 0.5 mm.

6. A lightweight fixed universal joint for rear axles according to claim 1, characterized in that: The inner ball track one (100) and the inner ball track two (110) are arranged in four alternating groups along the inner spherical surface (11), and the outer ball track one (300) and the outer ball track two (310) are arranged in four alternating groups along the outer spherical surface (31); the steel balls (4) are distributed in eight equidistant groups along the center line of the cage (2).

7. A lightweight fixed universal joint for rear axles according to claim 6, characterized in that: The trajectory of the steel ball (4) moving along the inner track one (100), the outer track one (300), the inner track two (110) and the outer track two (310) is arc-shaped.

8. A lightweight fixed universal joint for rear axles according to claim 1, characterized in that: The opening angle αi = the opening angle αo = 14°, and the opening angle αi and the opening angle αo are opposite in orientation.

9. A lightweight fixed universal joint for rear axles according to any one of claims 1 to 8, characterized in that: The inner ball track one (100) and the inner ball track two (110) on the outer ball cage (1) are both provided with a riveting structure for riveting the steel ball (4). The riveting structure is located on the outermost side of the inner ball track one (100) and the inner ball track two (110). The steel ball (4) can move along the inner ball track one (100) and the inner ball track two (110) to the maximum extent.

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