A large-angle multi-steel-ball constant-velocity Cardan joint

Abstract

The present invention discloses a large-angle multi-ball ball cage constant velocity universal joint, wherein the center line of the inner spherical surface where the inner cavity of the bell housing is located coincides with the center line of the outer spherical surface where the outer surface of the star gear sleeve is located; in the 0-degree state of the universal joint, when the steel ball rolls along the inner raceway of the bell housing, the trajectory of the center of the steel ball is a single-segment arc A, and when the steel ball rolls along the outer raceway of the star gear sleeve, the trajectory of the center of the steel ball is a single-segment arc B; the centers of the arc A and the arc B are both on the axis of the universal joint; the eccentricity between the center line of the arc A and the center line of the inner / outer spherical surface is E1; the eccentricity between the center line of the arc B and the center line of the inner / outer spherical surface is E2; E2 = D3 / 2 * TAN(12~19), E1 = (1.3~2.2) * E2. The maximum envelope outer diameter of the bell housing of the present invention is relatively small. On the basis that the diameter of the shaft rod is not reduced, the static torsion and fatigue strength are not reduced, and the durability of the universal joint remains unchanged or is further improved, the maximum angle can reach 52° or even a larger angle.

Description

Technical Field

[0001] The present invention belongs to the field of automotive parts and relates to a large-angle multi-ball ball cage constant velocity universal joint. Background Art

[0002] The high-performance constant velocity universal drive shaft assembly of a passenger car usually consists of a fixed universal joint, a sliding universal joint, and an intermediate shaft connected between the universal joints. With the global resource tension and the increasing attention of governments around the world to environmental protection, the lightweight of automobiles has become an inevitable trend in the current development of the automotive industry. This requires that the universal joint should adopt a compression design as much as possible, with a small envelope size, high strength and durability. At the same time, the universal joint needs to have the characteristics of high efficiency to avoid power loss. In addition, the turning radius of the automobile is required to be as small as possible to facilitate vehicle turning, which requires the universal joint to have a larger maximum angle.

[0003] Traditional ball cage constant velocity universal joints include: RZ type and UF type. The maximum angle of the former can only reach 47°, and the maximum angle of the latter can only reach 50°, neither of which can reach 52°. For the new ball cage constant velocity universal joints disclosed in the literature, the maximum universal joint angle can reach 52°, but when the universal joint trajectory is in the shape of an S or composed of multiple arcs and straight lines, a larger maximum envelope outer diameter of the bell housing is required, the weight is heavier, the raceway trajectory is complex, and the processing is complex. Unless there is a specific multi-axis hard milling equipment for processing, it cannot be processed with an ordinary imported grinding machine. The processing cost and detection cost are both high, which limits the further lightweight development of automobiles. In addition, no matter how the shape of the raceway trajectory of the traditional ball cage constant velocity universal joint changes, for the bell housing and the star-shaped sleeve, the offset distance between the raceway and the spherical surface always remains basically the same, or there are extremely small differences, and the maximum difference can only reach 0.1 mm. Summary of the Invention

[0004] The purpose of the present invention is to solve the above problems existing in the prior art and provide a large-angle multi-ball ball cage constant velocity universal joint. The maximum envelope outer diameter of the bell housing of this universal joint is smaller than that of other types of universal joints of the same specification. On the basis that the shaft diameter, static torque and fatigue strength are not reduced, and the durability of the universal joint remains unchanged or is further improved, the maximum angle can reach 52° or even a larger angle, the trajectory is simple, the shape is simple, it is convenient for processing, and the cost is relatively low.

[0005] To achieve the above object, the technical solution of the present invention is: a large-angle multi-steel ball constant velocity universal joint, including a bell housing with an inner cavity, a star gear located in the inner cavity of the bell housing, an annular cage, and n steel balls, where n = 6, 7, 8, 9, 10; there are n steel balls maintained in a plane by an annular cage with n evenly spaced windows between the raceway of the star gear and the raceway of the bell housing, and there is an interference fit between the two raceways and the steel balls; the inner wall of the bell housing and the outer wall of the annular cage form a set of spherical pairs, and the inner wall of the annular cage and the outer wall of the star gear form another set of spherical pairs, and both sets of spherical pairs are in a small clearance fit; the spherical surface where the inner cavity of the bell housing is located is the inner spherical surface, and the spherical surface where the outer surface of the star gear is located is the outer spherical surface, and the center lines of the inner spherical surface and the outer spherical surface coincide; there are n identical inner raceways opened on the inner cavity surface of the bell housing, and n identical outer raceways are opened on the outer surface of the star gear at positions corresponding to the inner raceways; when the steel ball rolls along the inner raceway of the bell housing, the trajectory of the center of the steel ball is a single-segment arc A, and when the steel ball rolls along the outer raceway of the star gear, the trajectory of the center of the steel ball is a single-segment arc B; in the 0-degree state of the universal joint, the centers of arc A and arc B are both on the axis of the universal joint; the center line of arc A is located on the side of the axis of the universal joint rod, and the eccentricity from the center line of the inner / outer spherical surface is E1; the center line of arc B is located on the side of the mouth of the bell housing, and the eccentricity from the center line of the inner / outer spherical surface is E2; the diameter D of each steel ball and the diameter D3 of the circle where the center of each steel ball is located are known values, and the offset distance E2 of the outer raceway of the star gear = D3 / 2 * TAN(12°~19°), and the offset distance E1 of the inner raceway of the bell housing = (1.3~2.2) * E2.

[0006] Further preferably, the outer spherical surface diameter D5 of the cage = D3 + (7 mm ~ 9 mm), and the inner spherical surface diameter D6 = D3 - (3 mm ~ 7 mm).

[0007] Further preferably, the diameter D2 at the mating part of the bell housing and the dust cover = D3 + D + (20 mm ~ 32 mm).

[0008] Further preferably, the maximum outer diameter D1 of the bell housing = D2 + (0 mm ~ 0.5 mm).

[0009] The present invention realizes the function of a universal joint with a large angle (up to 52° or even a larger angle) by specifically designing the offset distance ratio between the bell housing and the spider sleeve to form a large gap. On the basis of not reducing the static torque, quasi-static torque and fatigue strength, not reducing the wear performance, not reducing the durability and even improving the durability, without increasing the envelope size and even having a smaller maximum outer diameter of the bell housing envelope compared with other types of universal joints of the same specification, and without reducing the shaft diameter, by setting a large difference in the offset distance between the bell housing and the spider sleeve, and then shortening the axial displacement of the steel ball on the bell housing track. When the steel ball rolls along the inner raceway of the bell housing, the trajectory of the steel ball center and when the steel ball rolls along the outer raceway of the spider sleeve, the trajectory of the steel ball center are both single-segment arcs, with simple trajectories and simple shapes, which are convenient for processing, have lower processing costs and lower detection costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 FIG. is a schematic diagram of the internal structure of the present invention in the 0° angle state;

[0011] Figure 2 FIG. is a schematic diagram of the internal structure of the present invention in the 52° angle state;

[0012] Figure 3 FIG. is a front view cross-sectional view of the bell housing in the present invention;

[0013] Figure 4 FIG. is a front view cross-sectional view of the spider sleeve in the present invention;

[0014] Figure 5 FIG. is a left view of the spider sleeve in the present invention;

[0015] Figure 6 FIG. is a front view cross-sectional view of the cage in the present invention;

[0016] Figure 7 FIG. is a right view of the cage in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] The following further describes the present invention in conjunction with specific embodiments.

[0018] As Figures 1 to 7As shown in the figure, this embodiment includes a bell-shaped housing 2 with an inner cavity, a star-shaped sleeve 1 located in the inner cavity of the bell-shaped housing 2, an annular cage 3, and eight (which can also be six, seven, nine, or ten) steel balls 4. There are eight steel balls 4 maintained in a plane by an annular cage 3 with eight (which can also be six, seven, nine, or ten) windows 9 evenly distributed between the raceways of the star-shaped sleeve 1 and the raceways of the bell-shaped housing 2. There is an interference fit between the two raceways and the steel balls 4. The inner wall of the bell-shaped housing 2 and the outer wall of the annular cage 3 form a set of spherical pairs, and the inner wall of the annular cage 3 and the outer wall of the star-shaped sleeve 1 form another set of spherical pairs. Both sets of spherical pairs are in small clearance fit. The spherical surface where the inner cavity of the bell-shaped housing 2 is located is the inner spherical surface, and the spherical surface where the outer surface of the star-shaped sleeve 1 is located is the outer spherical surface. The center line 6 of the inner spherical surface coincides with the center line 7 of the outer spherical surface. Eight identical inner raceways 11 are provided on the inner surface of the bell-shaped housing 2, and eight identical outer raceways 10 are provided on the outer surface of the star-shaped sleeve 1 at positions corresponding to the inner raceways. When the steel ball 4 rolls along the inner raceway 11 of the bell-shaped housing 2, the trajectory of the center of the steel ball is a single-segment arc A, and when the steel ball 4 rolls along the outer raceway 10 of the star-shaped sleeve 1, the trajectory of the center of the steel ball is a single-segment arc B. In the 0° angle state of the universal joint, the centers of arc A and arc B are both on the universal joint axis 12. The center line 8 of arc A is located on the axonometric view of the universal joint shaft, and the eccentricity from the inner / outer spherical surface center line is E1; the center line 5 of arc B is located on the side of the bell-shaped housing mouth, and the eccentricity from the inner / outer spherical surface center line is E2. The diameter D of each steel ball is a given value, and the diameter D3 of the circle where the centers of each steel ball are located is set according to D and the evaluation of the wear performance of the universal joint, and it is also a known value. The offset distance E2 of the outer raceway of the star-shaped sleeve 1 = D3 / 2 * TAN(12°~19°), and the offset distance E1 of the inner raceway of the bell-shaped housing 2 = (1.3~2.2) * E2.

[0019] The offset distance E1 of the bell-shaped housing 2 and the offset distance E2 of the star-shaped sleeve 1 in this embodiment are not equal, and E1 = (1.3~2.2) * E2. The following examples are used to schematically analyze the relationship between the deflection angle of the cage 3 and the universal joint angle. See Figure 2 , assuming the universal joint angle is 52°, the offset distance E1 = 6.9518 mm, and the offset distance E2 = 4.3449 mm. The two are 1.6 times, and the difference in their offset distances is relatively large.

[0020] A is the center of the star-shaped sleeve raceway, B is the center of the bell-shaped housing raceway, and O is the center of the circle where the centers of each steel ball are located. In triangle AOB, the angle ∠AOB = 180° - 52° = 128°.

[0021] Using the cosine theorem, the value of AB can be calculated. AB = SQRT(E1^2 + E2^2 - 2 * E1 * E2 * COS(128°)) = 10.218,

[0022] Using the sine theorem, ∠ABO can be calculated as ASIN(E2 / (E1 / SIN(128°)) = 19.578°,

[0023] The deflection angle of the cage is ∠O1OO1’ = 19.578°, which is the angle of rotation of the cage.

[0024] Thus, it can be known that when the universal joint angle is 52°, the deflection angle of the cage is 19.578°. This angle is smaller than the deflection angle of the cage of the conventional universal joint. Therefore, the projection length of the stroke of the steel ball on the raceway in the bell housing in the axial direction is relatively small, meeting the stroke requirement and enabling the realization of a large angle of the universal joint. At the same time, the maximum outer diameter of the bell housing envelope of this universal joint is relatively small compared to other types of universal joints of the same specification.

[0025] Preferably, the outer spherical diameter D5 of the cage 3 = D3 + (7 mm to 9 mm); the inner spherical diameter D6 of the cage 3 = D3 - (3 mm to 7 mm).

[0026] Preferably, the diameter D2 at the mating part of the bell housing 2 and the dust cover = D3 + D + (20 mm to 32 mm).

[0027] Preferably, the maximum outer diameter D1 of the bell housing 2 = D2 + (0 mm to 0.5 mm).

[0028] O1'A' and O1'B' come from Figure 1 , O1A and O1B come from Figure 2 , which respectively represent the line segments between the characteristic points of the universal joint at 0 degrees and a specific angle. O1A = O1'A' = SQRT((D3 / 2) ^ 2 - E2^2), O1B = O1'B' = SQRT((D3 / 2) ^ 2 - E1^2).

[0029] For a universal joint with given parameters, the values of the line segments O1A and O1B are constant, which respectively represent the distance from the center of the steel ball to the center of the raceway of the spider at the universal joint state and the distance from the center of the steel ball to the center of the raceway of the bell housing. At a universal joint angle of 0°, the centers of both raceways are on the longitudinal axis of the universal joint, and the raceway trajectory is a single arc with no radial offset of the center;

[0030] Since E1 < E2, thus O1A < O1B, but the difference between them is not large. Taking Figure 2 the example dimensions of

[0031] O1A = 34.208 mm, O1B = 34.265 mm, with a difference of 0.057 mm.

[0032] At any angle, the steel balls roll and slide between the inner raceway and the outer raceway. For the inner and outer raceways, they have a constant linear velocity V. Due to the different radii of O1A and O1B, the angular velocities ω are different with respect to the inner and outer raceways. For the outer raceway of the spider that is connected to the shaft rod, the angular velocity is ω1, and for the inner raceway of the bell housing, the angular velocity is ω2, where ω1 > ω2, but the difference is very small. Taking an example, ω2 = (34.208 / 34.265) * ω1 = 0.99834ω1.

[0033] That is to say, the rotational speed transmitted from the transmission end is transmitted to the universal joint at the wheel end and the wheel. The rotational speed will have an extremely small reduction. However, during the rotation and operation of the universal joint, the angular velocities of the spider and the bell housing, which represent the input and output parts respectively, remain constant, and the specific values differ very little, that is, the constant velocity property remains unchanged. Such a designed universal joint is still a pure constant velocity universal joint.

[0034] In Figure 1 , the wedge angle of the universal joint is δ = 2ε. Taking the example of Figure 2 , when the angle of the universal joint is 0°, the wedge angle is 18.9°; when the angle of the universal joint is 52°, the wedge angle is 17.1°. At this angle, the universal joint will not self-lock.

[0035] According to the dimension settings, within the range of 0° to 52° of the universal joint, the quasi-static torsional strength can reach the strength of the same-specification shielding constant velocity universal joint (because the rotation angle of the cage is small, and in the case of a large universal joint angle, the cage is strongly supported by the bell housing, so the quasi-static torsional strength is large. The quasi-static torsional strength mainly targets the strength of the cage at a large universal joint angle).

[0036] According to the dimension settings and the possible application of multiple steel balls, within the range of 0° to 52° of the universal joint, the wear performance of the corresponding design of the present invention is higher than that of the same-specification 6-ball shielding constant velocity universal joint (due to the application of multiple balls and the small deflection angle of the cage).

[0037] According to the dimension settings, within the range of 0° to 52° of the universal joint, the diameter of the shaft rod does not decrease, and the static torsional and fatigue strengths can meet the same requirements as those of the shielding constant velocity universal joint.

[0038] The above-described embodiments are only preferred and exemplary, and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A large-angle multi-steel ball constant velocity universal joint, characterized in that: It includes a bell-shaped housing with an inner cavity, a star-shaped sleeve located in the inner cavity of the bell-shaped housing, an annular cage, and n steel balls, where n = 6, 7, 8, 9, 10; there are n steel balls maintained in a plane by an annular cage with n evenly spaced windows between the raceways of the star-shaped sleeve and the raceways of the bell-shaped housing, and there is an interference fit between the two raceways and the steel balls; the inner wall of the bell-shaped housing and the outer wall of the annular cage form a set of spherical pairs, and the inner wall of the annular cage and the outer wall of the star-shaped sleeve form another set of spherical pairs, and both sets of spherical pairs are in small clearance fit; the spherical surface where the inner cavity of the bell-shaped housing is located is the inner spherical surface, and the spherical surface where the outer surface of the star-shaped sleeve is located is the outer spherical surface, and the center line of the inner spherical surface coincides with the center line of the outer spherical surface; there are n identical inner raceways provided on the inner surface of the inner cavity of the bell-shaped housing, and n identical outer raceways are provided on the outer surface of the star-shaped sleeve at positions corresponding to the inner raceways; when the steel balls roll along the inner raceways of the bell-shaped housing, the trajectory of the center of the steel balls is a single-segment arc A, and when the steel balls roll along the outer raceways of the star-shaped sleeve, the trajectory of the center of the steel balls is a single-segment arc B; in the 0-degree state of the universal joint, the centers of arc A and arc B are both on the axis of the universal joint; the center line of arc A is located on the side of the universal joint shaft rod, and the eccentricity from the inner / outer spherical surface center line is E1; the center line of arc B is located on the side of the mouth of the bell-shaped housing, and the eccentricity from the inner / outer spherical surface center line is E2; the diameter D of each steel ball and the diameter D3 of the circle where the center of each steel ball is located are known values, the offset distance E2 of the outer raceway of the star-shaped sleeve = D3 / 2 * TAN(12°~19°), and the offset distance E1 of the inner raceway of the bell-shaped housing = (1.3~2.2) * E2.

2. The large-angle multi-steel-ball constant-velocity universal joint according to claim 1, characterized in that: The outer spherical surface diameter D5 of the cage = D3 + (7 mm ~ 9 mm), and the inner spherical surface diameter D6 = D3 - (3 mm ~ 7 mm).

3. The large-angle multi-steel-ball constant velocity universal joint according to claim 1 or 2, characterized in that: The diameter D2 at the mating part of the bell-shaped housing and the dust cover = D3 + D + (20 mm ~ 32 mm).

4. The large-angle multi-steel-ball constant-velocity universal joint according to claim 3, characterized in that: The maximum outer diameter D1 of the bell-shaped housing = D2 + (0 mm ~ 0.5 mm).

5. The large-angle multi-steel ball constant velocity universal joint according to claim 1 or 2, characterized in that: The maximum outer diameter D1 of the bell-shaped housing = D2 + (0 mm ~ 0.5 mm).

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