Constant velocity joint

Abstract

This constant velocity joint comprises: an outer race including a plurality of outer ball tracks; an inner race including a plurality of inner ball tracks which are paired with the outer ball tracks; a plurality of balls, each disposed in a space formed by a paired outer ball track and inner ball track; and a ball cage disposed between the outer race and the inner race and accommodating the plurality of balls. The track trajectory of each outer ball track includes a center trajectory which has a circular arc shape and a first and a second side trajectory which continue from the center trajectory and are respectively disposed at an open side and a connection side of the outer race. The first side trajectory is inclined toward the longitudinal axis of the outer race.

Description

Constant velocity joint

[0001] The present disclosure relates to a constant velocity joint used to transmit rotational power of a vehicle.

[0002] The driveshaft, also known as a halfshaft, serves to transmit power to the wheels at a constant speed. It functions to minimize power loss while actively responding to steering displacement or vibrations and shocks from the road surface. Typically, a driveshaft includes an inboard joint that receives rotation from the transmission or motor, an outboard joint that transmits rotational force to the wheels, and an interconnecting shaft that links the inboard and outboard joints. Generally, the outboard joint is configured to allow for rotational displacement of the wheels, while the inboard joint has a structure capable of compensating for changes in displacement angle and axial length resulting from the movement of the outboard joint.

[0003] Outboard joints are configured to allow rotational displacement while not permitting axial longitudinal displacement, and are typically implemented as Rzeppa joints, which are classified as fixed constant velocity joints. A fixed constant velocity joint comprises an outer race, an inner race, a ball cage, and multiple balls. The ball cage is equipped with multiple windows arranged along the circumference, and the balls are housed within these windows. Additionally, the balls are inserted into ball tracks formed in the outer race and the inner race, respectively, acting as a medium for transmitting rotational force between the inner and outer races. Due to their structure, such fixed constant velocity joints exhibit high internal friction, resulting in a lower output torque relative to the input torque and reduced power transmission efficiency. This contributes to decreased vehicle fuel economy and reduced durability of the constant velocity joint. Therefore, it is necessary to reduce internal friction. In addition, in conventional high-angle constant velocity joints, the open side portion of the ball track of the outer race is formed as a straight ball track parallel to the longitudinal axis, which causes a problem where material is not properly filled during the forging of the inner race, and this can cause a problem where unmachined parts remain during the finishing process of the ball track. Furthermore, the connecting side portion of the ball track of the outer race is formed as a circular track, and the depth of the ball track at the inner end where the ball is located under high-angle conditions becomes shallow, resulting in a small thickness of the part supporting the ball, which is disadvantageous for securing strength under high-angle conditions.

[0004] The matters described in the technical background section of this invention are written to enhance understanding of the background of the invention and may include matters that are not prior art already known in the field to which this technology belongs.

[0005] The problem that the present invention aims to solve is to provide a constant velocity joint that reduces internal friction and facilitates the ejection of the mold during the forging of an inner race, thereby increasing the lifespan of the mold.

[0006] The technical problems that the present invention aims to solve are not limited to those mentioned above, and other technical problems not mentioned will be understood by those skilled in the art from the description below.

[0007] A constant velocity joint according to an embodiment of the present invention comprises: an outer race comprising a plurality of outer ball tracks; an inner race comprising a plurality of inner ball tracks paired with the outer ball tracks; a plurality of balls each disposed in the space formed by the paired outer ball tracks and the inner ball tracks; and a ball cage disposed between the outer race and the inner race and accommodating the plurality of balls. The track trajectory of the outer ball tracks includes a center trajectory in the shape of an arc, and first and second side trajectories that follow the center trajectory and are respectively disposed on the open side and the coupled side of the outer race. The first side trajectory is formed to be inclined toward the longitudinal axis of the outer race.

[0008] The above first side trajectory may have a straight line shape.

[0009] The first side trajectory above may be inclined at an angle ranging from 0.5 to 2 degrees toward the longitudinal axis of the outer race, based on a direction parallel to the longitudinal axis of the outer race.

[0010] The first side trajectory can be configured to correspond to the tangent of the center trajectory at the connection point connecting the center trajectory and the first side trajectory.

[0011] The above second side trajectory may have a straight line shape.

[0012] The second side trajectory can be configured to correspond to the tangent of the center trajectory at the connection point connecting the center trajectory and the second side trajectory.

[0013] The above first side trajectory may have an arc shape.

[0014] The radius of curvature of the first side trajectory may be larger than the radius of curvature of the center trajectory.

[0015] The center of curvature of the center trajectory may be located on the longitudinal axis of the outer race, and the center of curvature of the first side trajectory may be located beyond the longitudinal axis of the outer race.

[0016] The above second side trajectory may have an arc shape.

[0017]

[0018] The radius of curvature of the first and second side trajectories above may be larger than the radius of curvature of the center trajectory above.

[0019] The center of curvature of the center trajectory may be located on the longitudinal axis of the outer race, and the radii of curvature of the first and second side trajectories may be located beyond the longitudinal axis of the outer race.

[0020] The track trajectory of the inner race may have a shape that is symmetrical to the track trajectory of the outer race with respect to the joint center line.

[0021] The outer ball track and the inner ball track may have an opening angle facing the open side of the outer race in a non-angled state, and the opening angle may be in the range of 11 to 14 degrees.

[0022] The center trajectory and the first side trajectory may be connected to each other at a first connection point, and the center trajectory and the second side trajectory may be connected to each other at a second connection point. The first connection point may be spaced apart from the joint center line toward the open side of the outer race, and the second connection point may be spaced apart from the joint center line toward the joining side of the outer race. The center of curvature of the center trajectory may be spaced apart from the joint center line toward the open side of the outer race.

[0023] The center of curvature of the above center trajectory may be located on the longitudinal axis of the above outer race.

[0024] The angle between the line connecting the center of curvature of the center trajectory and the second connection point and the track center line passing through the center of curvature of the center trajectory and perpendicular to the longitudinal axis of the outer race may be in the range of 15 to 17 degrees.

[0025] A constant velocity joint according to another embodiment of the present invention comprises: an outer race comprising a plurality of outer ball tracks; an inner race comprising a plurality of inner ball tracks paired with the outer ball tracks; a plurality of balls respectively disposed in the space formed by the paired outer ball tracks and the inner ball tracks; and a ball cage disposed between the outer race and the inner race and accommodating the plurality of balls. The track trajectory of the outer ball tracks includes a center trajectory in the shape of an arc, and first and second side trajectories that follow the center trajectory and are respectively disposed on the open side and the coupling side of the outer race. The first side trajectory is formed to be inclined toward the longitudinal axis of the outer race. The outer ball tracks and the inner ball tracks have an opening angle toward the open side of the outer race in a non-angled state. The center of curvature of the center trajectory is spaced apart from the joint center line toward the open side of the outer race.

[0026] The above opening angle may be in the range of 11 to 14 degrees. The center trajectory and the first side trajectory may be connected to each other at a first connection point, and the center trajectory and the second side trajectory may be connected to each other at a second connection point. The first connection point may be spaced apart from the joint center line toward the open side of the outer race, and the second connection point may be spaced apart from the joint center line toward the joining side of the outer race. The angle between the line connecting the center of curvature of the center trajectory and the second connection point and the track center line passing through the center of curvature of the center trajectory and perpendicular to the longitudinal axis of the outer race may be in the range of 15 to 17 degrees.

[0027] The first side trajectory may have a straight line shape, and the first side trajectory may be inclined at an angle ranging from 0.5 to 2 degrees toward the longitudinal axis of the outer race with respect to a direction parallel to the longitudinal axis of the outer race.

[0028] According to the present invention, efficiency can be improved by reducing internal friction, and the lifespan of the mold can be increased by facilitating the ejection of the mold during the forging of the ine race.

[0029] In addition to this, various effects that can be obtained or predicted by the embodiments of the present invention are disclosed directly or implicitly in the detailed description of the embodiments of the present invention.

[0030] The drawings attached below are intended to aid in understanding the present invention and provide embodiments of the invention together with the detailed description. However, the technical features of the present invention are not limited to specific drawings, and the features disclosed in each drawing may be combined with one another to form new embodiments. The embodiments of this specification may be better understood by referring to the following description in conjunction with the attached drawings, in which similar reference numerals refer to identical or functionally similar elements.

[0031] FIG. 1 is a perspective view of a constant velocity joint according to an embodiment of the present invention.

[0032] FIG. 2 is an exploded perspective view of a constant velocity joint according to an embodiment of the present invention.

[0033] Figure 3 is a cross-sectional view taken along line AA of Figure 1.

[0034] FIG. 4 shows a cross-section of the outer race of a constant velocity joint according to an embodiment of the present invention.

[0035] FIG. 5 shows a cross-section of the inner race of a constant velocity joint according to an embodiment of the present invention.

[0036] Figure 6 is a diagram showing the simulation results of torque loss due to internal friction according to the joint angle of a constant velocity joint according to an embodiment of the present invention.

[0037] Figure 7 is a diagram showing the simulation results of the failure torque according to the joint angle of a constant velocity joint according to an embodiment of the present invention.

[0038] FIG. 8 shows a cross-section of the outer race of a constant velocity joint according to another embodiment of the present invention.

[0039] Embodiments of the present invention are described below with reference to the attached drawings so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the described embodiments.

[0040] The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the invention. As used herein, the singular form is intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “comprising” as used herein indicate the presence of the specified features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, components, and / or groups thereof. As used herein, the term “and / or” includes any one or all combinations of one or more items listed in association. The term “combined” indicates a physical relationship between two components where the components are directly connected to each other or indirectly connected through one or more mediating components.

[0041] In describing the components of the present invention, terms such as first, second, A, B, (a), (b), etc., may be used. These terms are intended only to distinguish the components from other components and do not limit the essence, order, or sequence of the components. Where it is stated that a component is "connected," "combined," or "connected" to another component, it should be understood that the component may be directly connected, combined, or connected to the other component, but that another component may also be "connected," "combined," or "connected" between each component.

[0042] FIG. 1 is a perspective view of a constant velocity joint according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view of a constant velocity joint according to an embodiment of the present invention. FIG. 3 is a cross-sectional view taken along line AA of FIG. 1. Referring to FIG. 1 to 3, the constant velocity joint (10) includes an outer race (11), an inner race (12), a plurality of balls (13), and a ball cage (14). Although not explicitly shown in the drawings, the outer race (11) and the inner race (12) may each be connected to different power transmission elements. The outer race (11) and the inner race (12) rotate at a constant velocity by the action of the balls (13), thereby enabling rotational power, i.e., torque transmission, between the power transmission elements each connected to the outer race (11) and the inner race (12). For example, the inner race (12) can be connected to the connecting shaft of the drive shaft through a spline connection, and the outer race (11) can be connected to the wheel hub through a spline connection.

[0043] The outer race (11), having a cross-sectional shape approximately U-shaped, includes a closed joint side (15), an open side (16), and an internal space (17). The outer race (11) forms a longitudinal axis (X), and the joint side (15) and the open side (16) are positioned opposite each other along the longitudinal axis (X). The inner race (12) is inserted into the internal space (17) of the outer joint (11) through the open side (16). The inner race (12) includes a through hole (19) formed along the longitudinal direction, and a power transmission element can be inserted into the through hole (19) and fastened to rotate together with the inner race (12).

[0044] The inner surface (21) forming the inner space (17) of the outer race (11) has a roughly spherical shape, and correspondingly, the outer surface (22) of the inner race (12) may have a roughly spherical shape. Additionally, correspondingly, the ball cage (14) may have an outer surface and an inner surface that are roughly spherical in shape. The outer surface of the ball cage (14) faces the inner surface (21) of the outer race (11), and the inner surface of the ball cage (14) faces the outer surface (22) of the inner race (12). The ball cage (14) includes a plurality of windows (23) that each accommodate a plurality of balls (13). Through this structure, as is known, the outer race (11) and the inner race (12) are configured to be able to form an angle between them. FIGS. 1 to 3 illustrate a state in which the outer race (11) and the inner race (12) are aligned coaxially, i.e., in a non-angled state, and in the angled state, relative angular displacement occurs between the inner race (12) and the outer race (11). When an angled state occurs between the outer race (11) and the inner race (12), angular displacement of the ball cage (14) occurs together, and at this time, positional displacement of the ball (13) also occurs.

[0045] The outer race (11) includes a plurality of outer ball tracks (27) formed by being recessed radially outward on the inner surface (21), and correspondingly, the inner race (12) includes a plurality of inner ball tracks (28) formed by being recessed radially inward on the outer surface (22). The outer ball tracks (27) and the inner ball tracks (28) form pairs, and each ball (13) is placed in the space formed by the pair of outer ball tracks (27) and inner ball tracks (28). The outer ball tracks (27) and the inner ball tracks (28) may each be provided in eight numbers and may be arranged at equal intervals along the circumferential direction. Accordingly, the balls (13) are also provided in eight numbers. By providing eight balls, the outer diameter of the outer race (11) can be significantly reduced compared to the case where six balls are used. For example, when using 6 balls, the outer diameter of the outer race must be about 100 mm to satisfy the requirements, but in the embodiment of the present invention, by using 8 balls, the outer diameter of the outer race can be about 90 mm. In this way, by using 8 balls, the outer diameter of the outer race can be reduced by approximately 10% or more compared to the case where 6 balls are used.

[0046] The paired outer ball track (27) and inner ball track (28) form a funnel angle (α) facing the open side (16) in a non-angled state, and the funnel angle (α) can be set to fall within the range of 11 to 14 degrees. Since locking may occur when the angle is cut if the funnel angle is smaller than 11 degrees, the lower limit of the funnel angle is set to 11 degrees. In addition, by setting the upper limit to 14 degrees, which is smaller than the 16 degrees of the funnel angle of a typical fixed constant velocity joint, internal friction caused by the funnel angle is minimized, and accordingly, the loss of output torque relative to input torque is minimized, thereby maximizing efficiency. Here, the funnel angle may refer to the angle formed by the tangent at the point of contact between the ball and the outer ball track and the tangent at the point of contact with the inner ball track, or the angle formed between the center trajectory of the ball moving on the outer ball track and the center trajectory of the ball moving on the inner ball track.

[0047] FIG. 4 shows a cross-section of the outer race of a constant velocity joint according to an embodiment of the present invention, and FIG. 5 shows a cross-section of the inner race of a constant velocity joint according to an embodiment of the present invention. FIG. 6 shows a cross-section of the outer race, inner race, and ball of a constant velocity joint in a non-angled state according to an embodiment of the present invention.

[0048] Referring to FIG. 4, the track trajectory (31) of the outer ball track (27) comprises three parts: a center trajectory (32), and first and second side trajectories (33, 34) respectively connected to the center trajectory (32). The center trajectory (32) intersects the joint center line (C0). The first side trajectory (33) is connected to the center trajectory (32) so as to be located on the open side (16), and the second side trajectory (34) is connected to the center trajectory (32) so as to be located on the connected side (15). That is, a first connection point (P) connecting the center trajectory (32) and the first side trajectory (33). O1) is spaced apart from the joint center line (C0) toward the open side (16), and a second connection point (P) connecting the center trajectory (32) and the second side trajectory (34) O2 ) is spaced apart from the joint center line (C0) toward the joining side (15). At this time, the track trajectory (31) can be understood as the trajectory formed by the center of the ball (13) when the ball (13) moves on the outer ball track (27), and the joint center line (C0) can be understood as a line passing through the centers of the balls (13) facing each other in a non-angled state as shown in FIG. 3.

[0049] The center trajectory (32) of the outer ball track (27) has an arc shape, and the center of curvature (P) of the center trajectory (32) OC ) is positioned on the longitudinal axis (X) of the outer race (11) and is spaced apart from the joint center line (C0) toward the open side (16). Here, the center of curvature (P) of the arc-shaped center trajectory (32) OC The ball track center line (C) is a line perpendicular to the longitudinal axis (X) while passing through ) OT Defined as ). The center of curvature (P) of the center trajectory (32) OC ) and the second connection point (P O2 The line connecting ) and the ball track center line (C OT The angle (A1) between ) is set to fall within the range of 15 to 17 degrees.

[0050] The center of curvature (P) of the center trajectory (32) C ) and the second connection point (P O2 The line connecting ) and the ball track center line (C OT The angle (A1) between ) is made to fall within this range, and the second side trajectory (34) is the second connection point (P O2By making it a tangent at ), the amount of the side surface of the track supporting the ball (13) can be made larger than that of a conventional wave joint, thereby enabling relatively large torsional strength under high angle of cut conditions. When the constant velocity joint (10) forms an angle of approximately 20 degrees, the position of the ball (13) is approximately at the second connection point (P O2 It is located at ). Since the angle of cut is less than 20 degrees under normal driving conditions of the vehicle, when the angle of cut is 20 degrees or less for efficiency, the ball (13) moves on a center trajectory (32) without discontinuous sections, thereby maintaining the torque efficiency of the vehicle advantageously.

[0051] The first side trajectory (33) has a straight line shape inclined toward the longitudinal axis (X) with respect to a direction parallel to the longitudinal axis (X) of the outer race (11). That is, the angle (A2) between the first side trajectory (33) and the line (X0) parallel to the longitudinal axis (X) of the outer race (11) is set to fall within the range of 0.5 to 2 degrees. The first side trajectory (33) is the second connection point (P O2 It is configured to correspond to the tangent of the center trajectory (32) at ), and for this purpose, the first connection point (P O1 ) is the ball track center line (C T It is slightly spaced apart from the open side (16) from ). The second side trajectory (34) may also have a straight line shape, and the second connection point (P O2 It is configured to correspond to the tangent of the arc-shaped center trajectory (32) in ).

[0052] The track trajectory (41) of the inner ball track (28) can be formed to be symmetrical with respect to the outer ball track (27). Referring to FIG. 5, the track trajectory (41) of the inner ball track (28) includes a center trajectory (42) and first and second side trajectories (43, 44) respectively connected to the center trajectory (42). The center trajectory (42) intersects the joint center line (C0). The first side trajectory (43) is connected to the center trajectory (42) so as to be located on the open side (16), and the second side trajectory (44) is connected to the center trajectory (42) so as to be located on the joining side (15). That is, a first connection point (P) connecting the center trajectory (42) and the first side trajectory (43). I1 ) is spaced apart from the joint center line (C0) toward the open side (16), and a second connection point (P) connecting the center trajectory (42) and the second side trajectory (44) I2 ) is spaced apart from the joint center line (C0) toward the joining side (15). At this time, the track trajectory (41) can be understood as the trajectory formed by the center of the ball (13) as the ball (13) moves on the inner ball track (28).

[0053] The center trajectory (42) of the inner ball track (28) corresponds to the center trajectory (32) of the outer ball track (27) and has a shape symmetrical to the center line (32) of the outer ball track (27) with respect to the joint center line (C0). That is, the center trajectory (42) of the inner ball track (28) has an arc shape, and the center of curvature (P) of the center trajectory (42) C ) is spaced apart from the joint center line (C0) toward the open side (16). Here, the center of curvature (P) of the arc-shaped center trajectory (42) IC The ball track center line (C) that passes through ) and is perpendicular to the longitudinal axis (X1). IT Defined as ).

[0054] The first side trajectory (43) may have a straight line shape, and the first connection point (P I1It is configured to correspond to the tangent of the arc-shaped center trajectory (42) in ). The second side trajectory (43) is the longitudinal axis (X) of the inner race (12). I The longitudinal axis (X) with respect to the direction parallel to ) I It has a straight line shape that is tilted toward the ) side. That is, the second side trajectory (43) is tilted so that it gets closer to the longitudinal axis (X1) as it moves to the left in FIG. 4.

[0055] As explained above, by having the first side trajectory (33) of the outer ball track (27) have a straight line shape inclined toward the longitudinal axis (X) of the outer race (11), the second side trajectory (44) of the inner ball track (28) is also symmetrically inclined toward the longitudinal axis (X) of the inner race (12). I It has a straight line shape inclined toward the direction of the inner race, and accordingly, it can easily come out of the mold during cold forging in the manufacturing process of the inner race, and as a result, the load on the mold is reduced, and the lifespan of the mold can be increased. In addition, as described above, the angle (A2) between the first side trajectory (33) and the line (X0) parallel to the longitudinal axis (X) of the outer race (11) is set to fall within the range of 0.5 to 2 degrees, and if the angle (A2) is less than 0.5 degrees, the mold cannot come out easily, and a load may be applied to the mold. In addition, the reason for setting the upper limit of the angle (A2) to 2 degrees is that if it is greater than 2 degrees, it causes an unfavorable result in which the maximum cutting amount of the joint is reduced.

[0056] FIG. 6 is a diagram showing the simulation results of torque loss due to internal friction according to the joint angle of a constant velocity joint according to an embodiment of the present invention, and FIG. 7 is a diagram showing the simulation results of failure torque according to the joint angle of a constant velocity joint according to an embodiment of the present invention. Referring to FIG. 6, the constant velocity joint according to an embodiment of the present invention can reduce torque loss due to internal friction compared to a conventional joint. While conventional Z-wave joints typically have an opening angle of 16 degrees, the opening angle of the constant velocity joint according to an embodiment of the present invention is set low in the range of 11 to 14 degrees, thereby reducing internal friction and improving the fuel efficiency of the vehicle and the durability of the joint. Additionally, referring to FIG. 7, while the ball track of a conventional general Z-wave joint has a single arc-shaped ball track trajectory, the ball track of the constant velocity joint according to an embodiment of the present invention includes one arc-shaped trajectory and two straight trajectories, so strength can be significantly improved under high-angle conditions.

[0057] FIG. 8 shows a cross-section of the outer race of a constant velocity joint according to another embodiment of the present invention. Referring to FIG. 8, the outer race (60) includes a plurality of outer ball tracks (61) formed on the inner circumference, and the track trajectory (62) of the outer ball track (61) includes three trajectories, namely a center trajectory (63), a first side trajectory (64), and a second side trajectory (65). The center trajectory (63) and the first side trajectory (64) are at a first connection point (P 01 ) is connected by, and the center trajectory (63) and the second side trajectory (65) are connected by the second connection point (P 02 It is led by ).

[0058] All three trajectories (63, 64, 65) have arc shapes. The center trajectory (63) intersects the joint center line (C0), and the center of curvature (P) of the center trajectory (63) OC1) is located on the longitudinal axis (X) of the outer race (61) and is spaced apart from the joint center line (C0) toward the open side (66). Accordingly, the center of curvature (P) of the center trajectory (63) OC1 The ball track center line (C) passing through ) OT ) is spaced apart from the joint center line (C0) to the open side (66).

[0059] The radius of curvature of the first and second side trajectories (64, 65) is formed to be larger than the radius of curvature of the center trajectory (63). Specifically, the center of curvature (P) of the first side trajectory (64) OC2 The center of curvature (P) of the ) and the second side trajectory (65) OC3 ) is spaced apart from the joint center line (C0) toward the open side (66) and is located beyond the longitudinal axis (X) of the outer race. Also, the center of curvature (P) of the first side trajectory (64) OC2 ) is the joint center line (C0) and the ball track center line (C OT Located between ), and the center of curvature (P) of the second side trajectory (65). OC3 ) is the ball track center line (C OT It is spaced apart from the open side (66). By configuring the first side trajectory (64) located on the open side (66) into an arc shape and configuring the corresponding side trajectory of the inner race into an arc shape, the inner race can easily exit the mold during cold forging, thereby reducing the load on the mold and increasing the mold life. Additionally, since the second side trajectory (65) located on the joining side of the outer race has an arc shape, the amount of the side surface of the track supporting the ball is larger than that of a conventional joint, so relatively high strength can be secured under high angle of cut conditions.

[0060] Although embodiments of the present invention have been described above, the scope of the present invention is not limited thereto and includes all changes and modifications within the scope recognized as equivalents that can be easily changed by a person skilled in the art from the embodiments of the present invention.

Claims

1. An outer race including multiple outer ball tracks; An inner race comprising a plurality of inner ball tracks paired with the above outer ball track; A plurality of balls each disposed in the space formed by the paired outer ball track and the inner ball track; and It includes a ball cage disposed between the outer race and the inner race and accommodating the plurality of balls, The track trajectory of the outer ball track includes an arc-shaped center trajectory, and first and second side trajectories that follow the center trajectory and are respectively disposed on the open side and the connecting side of the outer race. The above first side trajectory is a constant velocity joint formed to be inclined toward the longitudinal axis of the outer race.

2. In Paragraph 1, The above first side trajectory is a constant velocity joint having a straight line shape.

3. In Paragraph 2, The above first side trajectory is a constant velocity joint that is inclined at an angle ranging from 0.5 to 2 degrees toward the longitudinal axis of the outer race, based on a direction parallel to the longitudinal axis of the outer race.

4. In Paragraph 3, The above first side trajectory is a constant velocity joint configured to correspond to the tangent of the center trajectory at the connection point connecting the center trajectory and the first side trajectory.

5. In Paragraph 2, The above second side trajectory is a constant velocity joint having a straight line shape.

6. In Paragraph 5, The above second side trajectory is a constant velocity joint configured to correspond to the tangent of the center trajectory at the connection point connecting the center trajectory and the second side trajectory.

7. In Paragraph 1, The above first side trajectory is a constant velocity joint having an arc shape.

8. In Paragraph 7, A constant velocity joint in which the radius of curvature of the first side trajectory is larger than the radius of curvature of the center trajectory.

9. In Paragraph 8, The center of curvature of the above center trajectory is located on the longitudinal axis of the above outer race, and The center of curvature of the first side trajectory is a constant velocity joint located beyond the longitudinal axis of the outer race.

10. In Paragraph 7, The above second side trajectory is a constant velocity joint having an arc shape.

11. In Paragraph 10, A constant velocity joint in which the radius of curvature of the first and second side trajectories is larger than the radius of curvature of the center trajectory.

12. In Paragraph 11, The center of curvature of the above center trajectory is located on the longitudinal axis of the above outer race, and The radius of curvature of the first and second side trajectories is a constant velocity joint located beyond the longitudinal axis of the outer race.

13. In Paragraph 1, A constant velocity joint having a shape in which the track trajectory of the inner race is symmetrical to the track trajectory of the outer race with respect to the joint center line.

14. In Paragraph 1, The outer ball track and the inner ball track have an opening angle facing the open side of the outer race in a non-angled state, and The above opening angle is a constant velocity joint in the range of 11 to 14 degrees.

15. In Paragraph 1, The above center trajectory and the above first side trajectory are connected to each other at a first connection point, and The above center trajectory and the above second side trajectory are connected to each other at a second connection point, and The first connection point is spaced apart from the joint center line toward the open side of the outer race, and The second connection point is spaced apart from the joint center line toward the joining side of the outer race, and The center of curvature of the above center trajectory is a constant velocity joint spaced apart from the joint center line toward the open side of the outer race.

16. In Paragraph 15, The center of curvature of the above center trajectory is a constant velocity joint located on the longitudinal axis of the above outer race.

17. In Paragraph 16, A constant velocity joint in which the angle between the line connecting the center of curvature of the center trajectory and the second connection point and the track center line passing through the center of curvature of the center trajectory and perpendicular to the longitudinal axis of the outer race falls within the range of 15 to 17 degrees.

18. An outer race comprising multiple outer ball tracks; An inner race comprising a plurality of inner ball tracks paired with the above outer ball track; A plurality of balls each disposed in the space formed by the paired outer ball track and the inner ball track; and It includes a ball cage disposed between the outer race and the inner race and accommodating the plurality of balls, The track trajectory of the outer ball track includes an arc-shaped center trajectory, and first and second side trajectories that follow the center trajectory and are respectively disposed on the open side and the connecting side of the outer race. The first side trajectory is formed to be inclined toward the longitudinal axis of the outer race, and The outer ball track and the inner ball track have an opening angle facing the open side of the outer race in a non-angled state, and The center of curvature of the above center trajectory is a constant velocity joint spaced apart from the joint center line toward the open side of the outer race.

19. In Paragraph 18, The above opening angle falls within the range of 11 to 14 degrees, and The above center trajectory and the above first side trajectory are connected to each other at a first connection point, and The above center trajectory and the above second side trajectory are connected to each other at a second connection point, and The first connection point is spaced apart from the joint center line toward the open side of the outer race, and The second connection point is spaced apart from the joint center line toward the joining side of the outer race, and A constant velocity joint in which the angle between the line connecting the center of curvature of the center trajectory and the second connection point and the track center line passing through the center of curvature of the center trajectory and perpendicular to the longitudinal axis of the outer race falls within the range of 15 to 17 degrees.

20. In Paragraph 18, The above first side trajectory has a straight line shape, and The above first side trajectory is a constant velocity joint that is inclined at an angle ranging from 0.5 to 2 degrees toward the longitudinal axis of the outer race, based on a direction parallel to the longitudinal axis of the outer race.

Images