Constant velocity joint and drive shaft comprising same

Abstract

This constant velocity joint comprises an outer race forming a plurality of outer ball tracks, an inner race forming a plurality of inner ball tracks corresponding to the plurality of outer ball tracks, a ball cage forming a plurality of windows, and a plurality of torque transfer balls respectively accommodated in the windows. The outer race and the inner race are configured to implement an articulation function causing a relative angular displacement with respect to each other. The inner race is fastened with the connection shaft of a drive shaft through a ball spline coupling structure. The ball spline coupling structure comprises an outer spline groove, an inner spline groove, a sleeve member, and a plurality of spline balls accommodated in a sleeve window formed in the sleeve member. The outer race has a spherical inner circumference having a first diameter, and the diagonal length of the inner race is less than the first diameter.

Description

Constant velocity joint and drive shaft including the same

[0001] The present disclosure relates to a constant velocity joint used to transmit driving force of an automobile and a driveshaft including the same.

[0002] A constant velocity joint (CVJ), a power transmission component, is a component of the drivetrain that transmits the driving force generated by a vehicle's power source, such as an internal combustion engine or electric motor, to the wheels. As is well known, CVJs are designed to transmit rotational driving force while allowing for angular and axial displacement that occurs during vehicle operation.

[0003] Typically, a constant velocity joint is formed as part of a so-called driveshaft or halfshaft. The driveshaft comprises a connecting shaft and a pair of constant velocity joints connected to each end of the shaft. Among the pair of constant velocity joints of the driveshaft, the constant velocity joint located on the widthwise inner side of the vehicle is commonly referred to as an inboard joint, and the constant velocity joint located on the widthwise outer side is commonly referred to as an outboard joint. Such a driveshaft is configured to have an axial displacement function in addition to the angular function of both constant velocity joints. A common method for implementing the axial displacement function of the driveshaft is to configure one of the constant velocity joints, particularly the inboard joint, as a constant velocity joint with a structure capable of axial displacement, such as a tripod constant velocity joint. However, the tripod constant velocity joint is structurally and cost-effectively disadvantaged compared to the so-called Rzeppa joint.

[0004] Another method for implementing axial displacement of a drive shaft is to apply a ball spline structure to the connecting shaft, as disclosed in Korean Patent No. 10-2179859, assigned to the applicant of the present application. Furthermore, when a vehicle starts suddenly, the vehicle can sway from side to side. This phenomenon is caused by the resonance between the generated axial force (GAF) of the drive shaft and the output of the engine or electric motor. Minimizing this phenomenon is a key issue in vehicle design, and a method using a premium tripod constant velocity joint that minimizes the axial force has been introduced to address this issue. However, the improvement achieved by applying this premium tripod constant velocity joint is limited in vehicles with high overall height. A drive shaft with a ball spline connecting shaft offers a promising alternative for reducing this phenomenon and offers the advantage of increasing overall vehicle height. Furthermore, the ball spline structure also offers the advantage of excellent NVH performance. However, connecting shafts with ball spline structures have diameters that are up to 60% larger than those of conventional hollow or solid connecting shafts, requiring a large installation space, which poses challenges in automotive design. Furthermore, connecting shafts with ball spline structures are heavier than conventional ones, negatively impacting fuel and electric vehicle efficiency. Furthermore, their manufacturing process is more complex, leading to higher manufacturing costs. Therefore, a solution that can overcome the aforementioned drawbacks while utilizing the numerous advantages of the ball spline structure is desired.

[0005] <Prior Art Literature>

[0006] - Republic of Korea Patent No. 10-2179859

[0007] The matters described in the technical background of this invention are written to enhance understanding of the background of the invention and may include matters that are not already known in the field to which this technology belongs.

[0008] The problem to be solved by the present invention is to provide a constant velocity joint and a drive shaft including the same, which can reduce the diameter and weight of a connecting shaft while adopting the advantages of a ball spline structure and have a simple manufacturing process and low manufacturing cost.

[0009] The technical problems to be solved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0010] A constant velocity joint configured to be coupled to a connecting shaft of a drive shaft according to an embodiment of the present invention includes an outer race forming a plurality of outer ball tracks, an inner race forming a plurality of inner ball tracks corresponding to the plurality of outer ball tracks, a ball cage interposed between the outer race and the inner race and forming a plurality of windows, and a plurality of torque transmitting balls each arranged in a space formed by a pair of the outer ball tracks and the inner ball tracks while being accommodated in each of the windows. The inner race is configured to be coupled to the connecting shaft through a ball spline coupling structure so as to implement a length displacement function due to relative displacement along the axial direction of the connecting shaft. The above ball spline coupling structure includes an outer spline groove provided on the inner race, an inner spline groove provided on the connecting shaft corresponding to the outer spline groove, a sleeve member interposed between the inner race and the connecting shaft, and a plurality of spline balls arranged in a space formed by the pair of outer and inner spline grooves while being accommodated in a sleeve window formed on the sleeve member. The outer race includes a spherical inner surface having a first diameter, and a diagonal length of the inner race is smaller than the first diameter.

[0011] The outer race may include a mating side and an open side, and the outer race may include a recessed space formed to accommodate at least a portion of an end of the connecting shaft when the connecting shaft is relatively displaced toward the mating side.

[0012] The above spline balls are arranged to form a row, and the row of spline balls can be arranged to overlap the torque transmitting balls along the axial direction of the constant velocity joint in a non-cut state of the constant velocity joint.

[0013] A drive shaft configured to transmit a rotational driving force according to an embodiment of the present invention includes a connecting shaft and a constant velocity joint connected to the connecting shaft. The constant velocity joint includes an outer race forming a plurality of outer ball tracks, an inner race forming a plurality of inner ball tracks corresponding to the plurality of outer ball tracks, a ball cage interposed between the outer race and the inner race and forming a plurality of windows, and a plurality of torque transmitting balls each arranged in a space formed by a pair of the outer ball tracks and the inner ball tracks while being accommodated in each of the windows. The inner race is connected to the connecting shaft through a ball spline coupling structure so as to enable longitudinal displacement. The above ball spline coupling structure includes an outer spline groove provided on the inner race, an inner spline groove provided on the connecting shaft corresponding to the outer spline groove, a sleeve member interposed between the inner race and the connecting shaft, and a plurality of spline balls arranged in a space formed by the pair of outer and inner spline grooves while being accommodated in a sleeve window formed on the sleeve member. The outer race includes a spherical inner surface having a first diameter, and a diagonal length of the inner race is smaller than the first diameter.

[0014] The above spline balls can be arranged to form a row, and the row of spline balls can be arranged to overlap the torque transmitting balls along the axial direction of the constant velocity joint in the non-cut state of the constant velocity joint.

[0015] The ball cage may include a first inclined surface provided on the inner surface of one end portion, and the inner race may include a second inclined surface provided on one end portion. The first and second inclined surfaces may be configured to contact each other when the ball cage and the inner race are bent relative to the outer race for assembly of the torque transmitting ball.

[0016] The outer race may include a mating side and an open side, and the outer race may include a recessed space formed to accommodate at least a portion of an end of the connecting shaft when the connecting shaft is relatively displaced toward the mating side.

[0017] The inner surface of the ball cage may include a sunken opening. The distance between the opposing openings may be formed to be greater than the outer diameter of the inner race, and the width of the opening may be greater than the width of the protrusion between the inner ball tracks of the inner race.

[0018] Ball center diameter (BCD) of the above torque transmitting ball TB ) for the diameter (D) of the torque transmitting ball TB ) of the ratio (=D) TB / BCD TB ) can be in the range of 0.243 to 0.279, and the ball center diameter (BCD) of the spline ball SB ) for the diameter of the above spline ball (D) SB ) of the ratio (=D) SB / BCD SB ) can be in the range of 0.116 to 0.185. The ball center diameter (BCD) of the torque transmitting ball TB ) of the above spline ball center diameter (BCD) SB ) of the ratio (=BCD) SB / BCD TB ) can range from 0.464 to 0.507.

[0019] A drive shaft configured to transmit a rotational driving force according to another embodiment of the present invention includes a connecting shaft and a constant velocity joint connected to the connecting shaft. The constant velocity joint includes an outer race forming a plurality of outer ball tracks, an inner race forming a plurality of inner ball tracks corresponding to the plurality of outer ball tracks, a ball cage interposed between the outer race and the inner race and forming a plurality of windows, and a plurality of torque transmitting balls each arranged in a space formed by a pair of the outer ball tracks and the inner ball tracks while being accommodated in each of the windows. The inner race is connected to the connecting shaft through a ball spline coupling structure so as to enable longitudinal displacement. The above ball spline coupling structure includes an outer spline groove provided on the inner race, an inner spline groove provided on the connecting shaft corresponding to the outer spline groove, a sleeve member interposed between the inner race and the connecting shaft, and a plurality of spline balls arranged in a space formed by the pair of outer and inner spline grooves in a state where they are received in a sleeve window formed on the sleeve member. The outer race includes a coupling side and an open side, and the outer race includes a recessed space formed so as to receive at least a portion of an end of the connecting shaft in a state where the connecting shaft is relatively displaced toward the coupling side.

[0020] According to the present invention, by connecting the inner race and the connecting shaft through a ball spline joint structure and imparting an axial length displacement function, the diameter and weight of the connecting shaft can be reduced. In addition, simplification of the manufacturing process and reduction in manufacturing costs can be achieved.

[0021] In addition, various effects that can be obtained or expected due to embodiments of the present invention are disclosed directly or implicitly in the detailed description of the embodiments of the present invention.

[0022] The accompanying drawings, which are intended to aid in understanding the present invention, provide embodiments of the present invention along with a detailed description. However, the technical features of the present invention are not limited to any specific drawings, and the features disclosed in each drawing may be combined to form new embodiments. The embodiments of the present specification may be better understood by referring to the following description in conjunction with the accompanying drawings, in which similar reference numerals designate identical or functionally similar elements.

[0023] Figure 1 is a drawing showing a drive shaft to which a constant velocity joint according to an embodiment of the present invention is applied.

[0024] Figure 2 is a perspective view of a constant velocity joint according to an embodiment of the present invention.

[0025] Figure 3 is a front view of a constant velocity joint according to an embodiment of the present invention.

[0026] Figure 4 is a cross-sectional view taken along line AA of Figure 3.

[0027] Figure 5 is a cross-sectional view taken along line BB of Figure 3.

[0028] Figure 6 is a partial cross-sectional view of a constant velocity joint according to an embodiment of the present invention.

[0029] FIG. 7 is a partial cross-sectional view showing a state in which the inner race is cut off relative to the outer race in a constant velocity joint according to an embodiment of the present invention.

[0030] Figure 8 is a longitudinal cross-sectional view of an outer race of a constant velocity joint according to an embodiment of the present invention.

[0031] Fig. 9 is a cross-sectional view of an outer race of a constant velocity joint according to an embodiment of the present invention.

[0032] Fig. 10 is a side view of an inner race according to an embodiment of the present invention.

[0033] Fig. 11 is a cross-sectional view taken along line CC of Fig. 10.

[0034] Figure 12 is a cross-sectional view taken along line DD of Figure 10.

[0035] Fig. 13 is a perspective view of a ball cage of a constant velocity joint according to an embodiment of the present invention.

[0036] Fig. 14 is a cross-sectional view of a ball cage of a constant velocity joint according to an embodiment of the present invention.

[0037] FIG. 15 is a drawing showing a state during the process of inserting the inner race of a constant velocity joint according to an embodiment of the present invention into a ball cage.

[0038] Fig. 16 is a drawing showing a state in which the inner race of a constant velocity joint according to an embodiment of the present invention is inserted into a ball cage.

[0039] FIG. 17 is a drawing for explaining a process of assembling a torque transmission ball in a constant velocity joint according to an embodiment of the present invention, with the inner race and ball cage assembled to the outer race.

[0040] Fig. 18 is a perspective view of a sleeve of a constant velocity joint according to an embodiment of the present invention.

[0041] Fig. 19 is a perspective view showing a state in which a ball is assembled to a sleeve of a constant velocity joint according to an embodiment of the present invention.

[0042] Fig. 20 is a cross-sectional view showing a state in which a ball spline coupling structure is applied to the inner race of a constant velocity joint according to an embodiment of the present invention.

[0043] Fig. 21 is a drawing showing a state in which the connecting shaft moves relative to the inner race in a moving-out direction in the state of Fig. 6.

[0044] Fig. 22 is a drawing showing a state in which the connecting shaft has moved relative to the inner race in the moving-in direction in the state of Fig. 6.

[0045] Fig. 23 is a cross-sectional view showing a state in which a cutting occurs in a drive shaft according to an embodiment of the present invention while the connecting shaft has moved as far as possible in the moving-in direction with respect to the inner race.

[0046] It should be understood that the drawings referenced above are not necessarily drawn to scale and are intended to provide brief representations of various features that illustrate the fundamental principles of the present invention. For example, specific design features of the present invention, including specific dimensions, orientations, positions, and shapes, will be determined in part by the specific intended application and usage environment.

[0047] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the described embodiments.

[0048] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It should also be understood that the terms "comprises" and / or "comprising," as used herein, indicate the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude 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 and all combinations of one or more of the associated listed items. The term "coupled" indicates a physical relationship between two components in which the components are directly connected to one another or are indirectly connected through one or more intervening components.

[0049] When describing components of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only intended to distinguish the components from other components, and the nature, order, or sequence of the components are not limited by the terms. When a component is described as being "connected," "coupled," or "connected" to another component, it should be understood that the component may be directly connected, coupled, or connected to the other component, but that another component may also be "connected," "coupled," or "connected" between each component.

[0050] FIG. 1 is a drawing showing a drive shaft (10) to which a constant velocity joint (13) according to an embodiment of the present invention is applied. Referring to FIG. 1, the drive shaft (10) includes an interconnecting shaft (11) and a pair of constant velocity joints (13, 14) each fastened to both ends of the interconnecting shaft (11). The interconnecting shaft (11) may be formed as a solid or hollow shaft, as necessary.

[0051] The constant velocity joints (13, 14) may be fixed constant velocity joints without an axial displacement function or plunge-type constant velocity joints with an axial displacement function. For example, the constant velocity joints (13, 14) may be so-called fixed constant velocity joints that do not have an axial displacement function or allow limited axial displacement by play, for example, constant velocity joints of the Rzeppa joint type. Either of the constant velocity joints (13, 14) may be used as an inboard joint and the other may be used as an outboard joint. For example, the constant velocity joint according to the embodiment of the present invention indicated by reference numeral 13 may be used as an inboard joint and the constant velocity joint indicated by reference numeral 14 may be used as an outboard joint. In Fig. 1, the constant velocity joint (13) is illustrated in a partially cut-away state.

[0052] Boots (15, 16) for grease sealing can be fastened to each of the constant velocity joints (13, 14). Both ends of the boot (15) can be fixed to the constant velocity joint (13) and the connecting shaft (11) by a fixing means such as a ring-shaped clamp, and both ends of the boot (16) can be fixed to the constant velocity joint (14) and the connecting shaft (11) by a fixing means such as a ring-shaped clamp, respectively.

[0053] Fig. 2 is a perspective view of a constant velocity joint according to an embodiment of the present invention, and Fig. 3 is a front view of a constant velocity joint according to an embodiment of the present invention. Fig. 8 is a cross-sectional view of an outer race of a constant velocity joint according to an embodiment of the present invention. Referring to Figs. 2, 3, and 8, a constant velocity joint (13) includes an outer race (21), an inner race (22), a ball cage (23), and a torque transmission ball (24). The outer race (21) may have a roughly U-shape with one side open and is configured to receive power from a power source.

[0054] The outer race (21) may have a closed-structured coupling side and an open side formed on the opposite side of the coupling side, and may be connected to a power source through the coupling side. In Fig. 8, the right side corresponds to the coupling side, and the left side corresponds to the open side. The inner race (22) and the ball cage (23) are inserted into the internal space of the outer race (21) through the open side of the outer race (21).

[0055] The inner race (22) is arranged in the inner space of the outer race (21). The inner race (22) is connected to the connecting shaft (11) in a power-transmittable manner so that rotational power can be transmitted to the connecting shaft (11). Power transmission between the inner race (22) and the connecting shaft (11) is achieved through a ball spline coupling structure (40) to be described later.

[0056] As shown in FIGS. 8 and 9, the outer race (21) forms outer ball tracks (25, 26) on the inner surface, and as shown in FIGS. 10 and 11, the inner race (22) forms inner ball tracks (27, 28) on the outer surface. The outer ball tracks (25, 26) and the inner ball tracks (27, 28) are formed at positions corresponding to each other, and a torque transmission ball (24) is arranged in a space formed by the pairs of outer and inner ball tracks (25, 27) (26, 28) corresponding to each other. Rotational power between the outer race (21) and the inner race (22) can be transmitted via the torque transmission balls (24). For example, the torque transmission balls (24) may be provided in eight numbers, and the eight torque transmission balls (24) may be arranged at equal intervals along the circumferential direction.

[0057] Referring to Figures 8 and 9, the inner surface (51) of the outer race (21) has an inner diameter (D O) is formed as a spherical surface, and the outer ball tracks (25, 26) can be formed by being sunken radially outward from the inner surface (51). Meanwhile, referring to FIGS. 10 to 12, the inner race (22) forms a through hole (31) extending in the axial direction, and the outer surface (52) of the inner race (22) has an outer diameter (D I ) is formed as a spherical surface, and the inner ball track (27, 28) can be formed by being sunken radially inward from the outer surface (52).

[0058] Fig. 13 is a perspective view of a ball cage of a constant velocity joint according to an embodiment of the present invention, and Fig. 14 is a cross-sectional view of a ball cage of a constant velocity joint according to an embodiment of the present invention. Referring to Figs. 3, 13, and 14, the ball cage (23) may be interposed between the inner circumferential surface of the outer race (21) and the outer circumferential surface of the inner race (22), and may include a plurality of windows (29) each accommodating a torque transmission ball (24). For example, the outer circumferential surface (53) and the inner circumferential surface (54) of the ball cage (23) may each be formed into a spherical surface.

[0059] Fig. 4 is a cross-sectional view taken along line AA of Fig. 3, and Fig. 5 is a cross-sectional view taken along line BB of Fig. 3. Referring to Figs. 4 and 5, the outer ball tracks (25) and the inner ball tracks (27), which are paired with each other, may form an opening angle (α) toward the open side, and the outer ball tracks (26) and the inner ball tracks (28), which are paired with each other, may form an opening angle (β) toward the engagement side. At this time, the pair of outer and inner ball tracks (25, 27) having the opening angle (α) toward the open side and the pair of outer and inner ball tracks (26, 28) having the opening angle (β) toward the engagement side may be arranged alternately along the circumferential direction. Here, the concept of opening angle is generally known in the technical field to which the present invention belongs, and may mean the angle formed between the central trajectory of a ball moving on the outer ball track and the central trajectory of a ball moving on the inner ball track. A constant velocity joint having opening angles facing opposite directions in a non-cut state like this is known as a so-called counter ball track joint. This can minimize the deflection of the ball cage (23) when torque is applied, thereby enabling self-centering of the ball cage (23) and reducing internal friction, which can minimize the loss of output torque compared to the input torque of the constant velocity joint, thereby contributing to improving fuel efficiency or power efficiency of the vehicle.

[0060] The constant velocity joint (13) according to the embodiment of the present invention can be configured to allow angular displacement of the outer race (21) and the inner race (22), i.e., an angular function, to be achieved. For example, the outer race (21), the inner race (22), and the ball cage (23) are configured in the form of a zebra joint so that relative angular displacement of the outer race (21) and the inner race (22) can be achieved. FIG. 6 illustrates a case where the outer race (21) and the inner race (22) are aligned, i.e., in a non-angular state, and FIG. 7 illustrates a state where the inner race (22) is angular with respect to the outer race (21). The angular angle (A1) shown in FIG. 7 means the angle formed by the axial direction (X1) of the constant velocity joint (13) with respect to the axial direction of the drive shaft (10), i.e., the axial direction (X) of the connecting shaft (11).

[0061] The constant velocity joint (13) according to an embodiment of the present invention is configured so that the angular function and the axial displacement function occur separately from each other. The angular function can be implemented through the inner surface of the outer race (21), the outer surface of the inner race (22), and the shape of the ball cage (23) as described above. Meanwhile, the axial displacement function is for the longitudinal displacement of the drive shaft (10) in the axial direction (X), and is implemented through a ball spline joint structure between the inner race (22) and the connecting shaft (11).

[0062] In the embodiment of the present invention, by implementing the length displacement function through the ball spline joint structure between the inner race (22) and the connecting shaft (11), there is no need to configure the connecting shaft as a tubular shaft as in the past, and the outer diameter of the connecting shaft can be significantly reduced to be close to that of a conventional solid connecting shaft without a length displacement function. In this respect, the connecting shaft (11) can be applied as a solid shaft. The reduction in the outer diameter of the connecting shaft leads to an improvement in the degree of freedom for the interior space during automobile design. In addition, by implementing the length displacement function through the ball spline joint structure between the inner race (22) and the connecting shaft (11), the weight can be reduced and the manufacturing cost can also be significantly reduced compared to the case where the length displacement function is applied to a conventional tubular connecting shaft. In addition, the application of the ball spline joint structure can significantly reduce the axial induced force (GAF) of the automobile, which provides superior NVH performance compared to a conventional constant velocity joint.

[0063] Referring to FIGS. 13 and 14, the ball cage (23) includes an opening (61) for assembling the inner race (22). As shown in FIG. 14, the opening (61) is formed so as to extend from one end of the window (29) to the end of the ball cage (23), and is formed in a sunken shape at the edge area of ​​the inner surface (54) of the ball cage (23). The openings (61) facing each other have an inlet diameter (D C ) and the inlet diameter (D C ) is the outer diameter (D) of the inner race (22) I ) is formed to be larger than (D C >D I ) In addition, the width (W) of the opening (61) C ) is the width (W) of the protrusion (56) of the inner race (22) shown in Fig. 11. I ) is formed to be larger than (W C > W I) By these structures and dimensions, as shown in FIGS. 15 and 16, the inner race (22) can be assembled into the ball cage (23) through the opening (61) of the ball cage (23).

[0064] FIG. 17 is a drawing for explaining a process of assembling a torque transmission ball (24) in a state where an inner race (22) and a ball cage (23) are assembled to an outer race (21) in a constant velocity joint according to an embodiment of the present invention. In order to assemble a torque transmission ball (24) in a state where the inner race (22) and the ball cage (23) are assembled to the outer race (21), the inner race (22) and the ball cage (23) must be bent at an appropriate angle or more with respect to the outer race (21), and for this purpose, the end of the inner race (22) bent during the angle cutting is configured to enter the internal space of the outer race (21). In order to implement this, the diagonal length (L) of the inner race (22) I ) is the inner diameter (D) of the inner surface (51) of the outer race (21) O ) is configured to be smaller than (L I < D O ) By this, the inner race (22) can be bent sufficiently as desired in the inner space of the outer race (21), so that the torque transmission ball (24) can be easily assembled into the window (29) of the ball cage (23) along the direction of the arrow in Fig. 17.

[0065] In order to allow the inner race (22) and ball cage (23) to be bent at a larger angle when assembling the torque transmitting ball (24), an inclined surface (63) is formed on the inner surface (54) of the ball cage (23), and correspondingly, an inclined surface (64) is formed on the outer surface of the inner race (22). The inclined surface (63) of the ball cage (23) is formed to be inclined so as to be radially outward from the spherical inner surface (54) of the ball cage (23), and the inclined surface (64) of the inner race (22) is formed to be inclined so as to be radially inward. As illustrated in the dotted circle of Fig. 17, the two inclined surfaces (63, 64) are configured to contact each other when the inner race (22) and the ball cage (23) are bent to the maximum extent, thereby allowing the inner race (22) and the ball cage (23) to be bent at a greater angle with respect to the outer race (21). Accordingly, when assembling the torque transmitting ball (24), the window (29) of the ball cage (23) can be more exposed to the outside of the outer race (21), thereby allowing the assembly of the torque transmitting ball (24).

[0066] The inner race (22) and the connecting shaft (11) are connected to each other so as to enable axial relative displacement while transmitting rotational power through a ball spline coupling structure (40). The ball spline coupling structure (40) includes a plurality of outer spline grooves (41), a plurality of inner spline grooves (42), a sleeve member (43), and a plurality of rows of spline balls (44). The rows of spline balls (44) are arranged to overlap the torque transmitting balls (24) along the axial direction of the constant velocity joint in the non-cut state of the constant velocity joint. The outer spline groove (41) is formed on the inner peripheral surface forming the through hole (31) of the inner race (22), as shown in FIGS. 11 and 12, and the inner spline groove (42) is formed correspondingly on the outer peripheral surface of the connecting shaft (11). The outer spline groove (41) and the inner spline groove (42) are paired with each other to form a space into which a plurality of rows of spline balls (44) are inserted. The outer spline groove (41) and the inner spline groove (42) extend in a direction parallel to the axial direction (X) of the connecting shaft (11), and the spline balls (44) are configured to roll and / or slide in the space formed by the outer and inner spline grooves (41, 42). Rolling and / or sliding of the spline balls (44) can cause an axial relative displacement between the inner race (22) and the connecting shaft (11), and the axial relative displacement between the inner race (22) and the connecting shaft (11) leads to a change in the axial length of the drive shaft (10). Meanwhile, the outer and inner spline grooves (41, 42) may have a cross-sectional shape such as an arch or a Gothic-arch, and the spline ball (44) may contact the side surfaces of the outer and inner spline grooves (41, 42) so that the inner race (22) and the connecting shaft (11) may rotate together about the axial direction (X).

[0067] Fig. 18 is a perspective view of a sleeve of a constant velocity joint according to an embodiment of the present invention, and Fig. 19 is a perspective view showing a state in which a ball is assembled to a sleeve of a constant velocity joint according to an embodiment of the present invention. Referring to Figs. 18 and 19, the sleeve member (43) may have a hollow cylinder shape having a thin thickness so as to be interposed in the space between the outer circumferential surface of the connecting shaft (11) and the inner circumferential surface of the inner race (22). The sleeve member (43) has a plurality of sleeve windows (45) each accommodating a plurality of rows of spline balls (44). The plurality of sleeve windows (45) may be arranged at equal intervals along the circumferential direction. Each sleeve window (45) extends in a direction parallel to the axial direction (X) of the connecting shaft (11). The radially outer portion of the spline ball (44) placed in the sleeve window (45) is accommodated in the outer spline groove (41), and the radially inner portion is accommodated in the inner spline groove (42).

[0068] Referring to FIGS. 18 and 19, a plurality of spline balls (44) forming a row are accommodated in each sleeve window (45), and at this time, adjacent spline balls (44) can be in contact with each other. The sleeve window (45) can be formed in the shape of a long hole having a constant width (W). Since a plurality of spline balls (44) are arranged to form a row in one long sleeve window (45), the total length (B) of the row of the same number of spline balls is reduced. This leads to a reduction in the length of the ball spline coupling structure (40), and a compact constant velocity joint can be implemented. That is, referring to FIG. 20, the length (B) of the row of the plurality of spline balls (44) is reduced, and thereby the total length (T) of the inner race (22) can be minimized while ensuring that the axial length displacements (L1, L2) satisfy the required values.

[0069] In addition, in an embodiment of the present invention, a plurality of spline balls (44) forming a row are accommodated in a single long sleeve window (45) at the same time, so that contact is made between the spline balls (44) during sliding and / or rolling behavior of the spline balls (44), which leads to a reduction in friction.

[0070] FIG. 21 is a drawing showing a state in which the connecting shaft has moved relative to the inner race in a moving-out direction in the state of FIG. 6, and FIG. 22 is a drawing showing a state in which the connecting shaft has moved relative to the inner race in a moving-in direction in the state of FIG. 6. FIG. 6 illustrates a state in which the centers of the rows of a plurality of spline balls (44) of the ball spline coupling structure (40) are aligned with the joint center plane (P), and when the connecting shaft (11) moves toward the open side of the outer race (21) in the state of FIG. 6, that is, moves in the moving-out direction (leftward in FIG. 21), it is located in the state of FIG. 21, and conversely, when it moves toward the coupling side of the outer race (21), that is, moves in the moving-in direction (rightward in FIG. 22), it is located in the state of FIG. 22. Fig. 21 illustrates a state in which the movement in the moving-out direction is maximum, and Fig. 22 illustrates a state in which the movement in the moving-in direction is maximum. Based on the position in Fig. 6, the maximum movement distance (L2) in the moving-out direction and the maximum movement distance (L1) in the moving-in direction can be understood as being equal to the corresponding length displacement amounts illustrated in Fig. 20. Through this ball spline coupling structure (40), a drive shaft having a determined total length displacement amount (=L1+L2) can be implemented.

[0071] A structure is applied to limit the range of movement of the connecting shaft (11) during the moving-out and moving-in behavior of the connecting shaft (11) and to prevent the spline ball (44) and the sleeve member (43) from coming off. Referring to FIGS. 6 and 21, a first movement limiting member, i.e., a first retaining ring (47), and a second movement limiting member, i.e., a second retaining ring (48), are provided to limit the movement of the spline ball (44) during the moving-out behavior of the connecting shaft (11). The first retaining ring (47) is installed on the inner surface of one end of the inner race (22) and configured to support the outermost spline ball (44), thereby preventing the spline ball (44) from coming off the inner race (22). Meanwhile, the second retaining ring (48) is installed on the outer surface of the end of the connecting shaft (11) and configured to support the outermost spline ball (44), thereby preventing the spline ball (44) from being separated from the connecting shaft (11). As shown in Fig. 21, when the connecting shaft (11) is moved as far as possible in the moving-out direction, the ends on both sides of the row of the plurality of spline balls (44) are respectively supported by the first retaining ring (47) and the second retaining ring (48). Accordingly, on the one hand, the spline ball (44) and the sleeve member (43) are prevented from being separated from the inner race (22), and on the other hand, the moving-out movement of the connecting shaft (11) is restricted.

[0072] Meanwhile, referring to FIG. 6 and FIG. 22, a third movement limiting member, i.e., a third retaining ring (49), is provided to limit the movement of the spline ball (44) when the connecting shaft (11) moves in the moving-in motion. The third retaining ring (49) is installed on the inner surface of the other end of the inner race (22) and configured to support the outermost spline ball (44), thereby preventing the spline ball (44) from being separated from the inner race (22). When the connecting shaft (11) is moved as much as possible in the moving-in direction as shown in FIG. 22, one end of a row of a plurality of spline balls (44) is supported by the third retaining ring (49). Accordingly, the spline ball (44) and the sleeve member (43) are prevented from being separated from the inner race (22) when the moving-in motion is performed.

[0073] As illustrated in FIGS. 21 and 22, the first to third retaining rings (47, 48, 49) are configured to contact the spline ball (44) without contacting the sleeve member (43). This prevents the sleeve member (43) from colliding with the first to third retaining rings (47, 48, 49) and being damaged. The first to third retaining rings (47, 48, 49) described above may also be installed by being inserted into the groove. Meanwhile, in another embodiment, the retaining rings may be replaced with staking portions formed by staking.

[0074] Fig. 23 is a cross-sectional view showing a state in which a cutting has occurred in a state in which a connecting shaft has moved to the maximum in the moving-in direction with respect to an inner race in a drive shaft according to an embodiment of the present invention. As illustrated in Figs. 8 and 23, the outer race (21) has a recessed space (67) to avoid interference with the connecting shaft (11) during cutting. The recessed space (67) may be positioned between the ends of the outer ball grooves (25, 26) and the mating side of the outer race (21) so as to avoid interference with the end of the connecting shaft (11) that has moved in the moving-in direction in the cutting state. The recessed space (67) may have an approximately ring shape that is recessed radially outward. Due to the recessed space (67), interference between the end of the connecting shaft (11) and the outer race (21) can be avoided as illustrated in Fig. 23, thereby enabling a larger cutting angle.

[0075] According to an embodiment of the present invention, for package optimization, the diameter (D) of the torque transmission ball (24) TB ), diameter (D) of spline ball (44) SB ), ball center diameter (BCD) of the torque transmission ball (24) TB ), and the ball center diameter (BCD) of the spline ball (44) SB ) regulates the size and ratio of the torque transmitting ball (24). Here, the ball center diameter (BCD, Ball Center Diameter) (BCD TB ) means the diameter of the circle formed by the centers of multiple torque transmitting balls (24) in a non-cutting state, and is indicated in Fig. 9. In addition, the ball center diameter (BCD) of the spline ball (44) SB ) means the diameter of the circle formed by the centers of multiple spline balls (44). The ball center diameter (BCD) of the torque transmitting ball (24) TB ) for the diameter (D) of the torque transmitting ball (24) TB ) of the ratio (=D) TB / BCD TB) can be a value in the range of 0.243 to 0.279, and the ball center diameter (BCD) of the spline ball (44) SB ) Diameter (D) of spline ball (44) SB ) of the ratio (=D) SB / BCD SB ) can be a value in the range of 0.116 to 0.185. Also, the ball center diameter (BCD) of the torque transmitting ball (24) TB ) Ball center diameter (BCD) of spline ball (44) SB ) of the ratio (=BCD) SB / BCD TB ) can be a value in the range of 0.464 to 0.507.

[0076] These values ​​were derived based on the allowable range of Hertz contact stress, which is a theoretical output value of durability performance, and the details are shown in Table 1 below.

[0077] ItemMinimumMedianMaximumTorque Transmission Ball Diameter (mm)17.0018.0019.00Number of Tracks (Balls)888BCD (mm)68.0069.0070.00Diameter / BCD0.2430.2610.279Hz Allowable range of contact stress - Applicable torque: 4,100 Nm - Optimum range: 2200~2400 MPA2,4092,3002,201Spline BallSpline Ball Diameter (mm)4.005.006.00Number of Grooves (Rows of Balls)888BCD (mm)32.5033.5034.50Diameter / BCD0.1160.1490.185Hz Allowable range of contact stress - Applicable torque: 4,100 Nm - Optimum range: 3400~4600 MPA4,5883,9143,432 BCD of spline ball / BCD of torque transmitting ball 0.4640.4860.507

[0078]

[0079] Although the 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 that can be easily modified by a person having ordinary skill in the art to which the present invention pertains and are recognized as equivalent from the embodiments of the present invention.

Claims

1. In a constant velocity joint configured to be connected to a connecting shaft of a drive shaft, Outer race forming multiple outer ball tracks; An inner race forming a plurality of inner ball tracks corresponding to the plurality of outer ball tracks, A ball cage interposed between the outer race and the inner race and forming a plurality of windows, and It includes a plurality of torque transmitting balls, each of which is arranged in a space formed by a pair of the outer ball track and the inner ball track, in a state where each is accommodated in the window, The above inner race is configured to be connected to the connecting shaft through a ball spline coupling structure so as to implement a length displacement function by relative displacement along the axial direction of the connecting shaft. The above ball spline joint structure An outer spline groove provided in the inner race above, An inner spline groove provided on the connecting shaft corresponding to the outer spline groove; A sleeve member interposed between the inner race and the connecting shaft, and It comprises a plurality of spline balls arranged in a space formed by a pair of outer and inner spline grooves so as to be received in a sleeve window formed in the sleeve member, The above outer race includes an inner surface having a spherical shape having a first diameter, A constant velocity joint in which the diagonal length of the inner race is smaller than the first diameter.

2. In paragraph 1, The above outer race includes a joining side and an open side, A constant velocity joint in which the outer race includes a recessed space formed so as to accommodate at least a portion of an end of the connecting shaft while the connecting shaft is relatively displaced toward the engaging side.

3. In paragraph 1, A constant velocity joint in which the above spline balls are arranged to form a row, and the row of spline balls is arranged to overlap the torque transmitting balls along the axial direction of the constant velocity joint in the non-cut state of the constant velocity joint.

4. In a drive shaft configured to transmit rotational driving force, connecting shaft, and Including a constant velocity joint connected to the above connecting shaft, The above constant velocity joint Outer race forming multiple outer ball tracks; An inner race forming a plurality of inner ball tracks corresponding to the plurality of outer ball tracks, A ball cage interposed between the outer race and the inner race and forming a plurality of windows, and It includes a plurality of torque transmitting balls, each of which is arranged in a space formed by a pair of the outer ball track and the inner ball track, in a state where each is accommodated in the window, The above inner race is connected to the connecting shaft through a ball spline joint structure to enable length displacement, The above ball spline joint structure An outer spline groove provided in the inner race above, An inner spline groove provided on the connecting shaft corresponding to the outer spline groove; A sleeve member interposed between the inner race and the connecting shaft, and It comprises a plurality of spline balls arranged in a space formed by a pair of outer and inner spline grooves so as to be received in a sleeve window formed in the sleeve member, The above outer race includes an inner surface having a spherical shape having a first diameter, A drive shaft having a diagonal length of the inner race smaller than the first diameter.

5. In paragraph 4, A drive shaft in which the above spline balls are arranged to form a row, and the row of spline balls is arranged to overlap the torque transmitting balls along the axial direction of the constant velocity joint in the non-cut state of the constant velocity joint.

6. In paragraph 4, The above ball cage includes a first inclined surface provided on the inner surface of one end, The inner race includes a second inclined surface provided on one end, A drive shaft wherein the first and second inclined surfaces are configured to contact each other when the ball cage and the inner race are bent relative to the outer race for assembly of the torque transmitting balls.

7. In paragraph 4, The above outer race includes a joining side and an open side, A drive shaft wherein the outer race includes a recessed space formed to accommodate at least a portion of an end of the connecting shaft when the connecting shaft is relatively displaced toward the engaging side.

8. In paragraph 4, The inner surface of the above ball cage includes an opening in a sunken shape, The distance between the above-mentioned openings facing each other is formed to be larger than the outer diameter of the inner race, A drive shaft wherein the width of the above opening is greater than the width of the projection between the inner ball tracks of the inner race.

9. In paragraph 4, Ball center diameter (BCD) of the above torque transmitting ball TB ) for the diameter of the torque transmitting ball (D) TB ) of the ratio (=D) TB / BCD TB ) is in the range of 0.243 to 0.279, Ball center diameter (BCD) of the above spline ball SB ) for the diameter of the above spline ball (D) SB ) of the ratio (=D) SB / BCD SB ) is in the range of 0.116 to 0.185, The ball center diameter (BCD) of the above torque transmitting ball TB ) for the above ball center diameter (BCD) of the above spline ball SB ) of the ratio (=BCD) SB / BCD TB ) is a drive shaft within the range of 0.464 to 0.

507.

10. In a drive shaft configured to transmit rotational driving force, connecting shaft, and Including a constant velocity joint connected to the above connecting shaft, The above constant velocity joint Outer race forming multiple outer ball tracks; An inner race forming a plurality of inner ball tracks corresponding to the plurality of outer ball tracks, A ball cage interposed between the outer race and the inner race and forming a plurality of windows, and It includes a plurality of torque transmitting balls, each of which is arranged in a space formed by a pair of the outer ball track and the inner ball track, in a state where each is accommodated in the window, The above inner race is connected to the connecting shaft through a ball spline joint structure to enable length displacement, The above ball spline joint structure An outer spline groove provided in the inner race above, An inner spline groove provided on the connecting shaft corresponding to the outer spline groove; A sleeve member interposed between the inner race and the connecting shaft, and It comprises a plurality of spline balls arranged in a space formed by a pair of outer and inner spline grooves so as to be received in a sleeve window formed in the sleeve member, The above outer race includes a joining side and an open side, A drive shaft wherein the outer race includes a recessed space formed to accommodate at least a portion of an end of the connecting shaft when the connecting shaft is relatively displaced toward the engaging side.

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