Constant velocity joint and driveshaft 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 transmission balls received in the respective windows. The outer race and the inner race are configured to enable the implementation of a tilting function causing relative angular displacement with respect to each other. The inner race is fastened to a connecting shaft of a driveshaft through a ball spline coupling structure. The ball spline coupling structure comprises: outer spline grooves; inner spline grooves; a sleeve member; and a plurality of spline balls received in sleeve windows formed in the sleeve member. The spline balls are arranged so as to form rows, and the rows of the spline balls are arranged so as to overlap the torque transmission balls along the axial direction of the constant velocity joint in the non-tilted state of the constant velocity joint.

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 outer race and the inner race are configured to be able to implement an angular function that causes a relative angular displacement with respect to each other. The inner race is coupled to the connecting shaft through a ball spline coupling structure so as to be able to implement a length displacement function due to a relative displacement along an axial direction of the connecting shaft. The above ball spline coupling structure includes an outer spline groove provided in the inner race, an inner spline groove provided in 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 a pair of the outer and inner spline grooves in a state of being received in a sleeve window formed in the sleeve member.

[0011] 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.

[0012] The above torque transmission balls can be provided in eight pieces.

[0013] The outer ball track may include a first outer ball track and a second outer ball track, and the inner ball track may include a first inner ball track paired with the first outer ball track and a second inner ball track paired with the second outer ball track. The pair of the first outer ball track and the first inner ball track and the pair of the second outer ball track and the second inner ball track may be configured to have opening angles in opposite directions when in a non-cut state.

[0014] The above outer race and the above inner race can be configured to allow axial relative displacement by a gap between the outer race and the inner race.

[0015] 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 outer race and the inner race are configured to be able to implement an angular function that causes a relative angular displacement with respect to each other. The inner race is connected to the connecting shaft through a ball spline coupling structure so as to be able to implement a length displacement function due to a relative displacement along an 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 in a state of being accommodated in a sleeve window formed on the sleeve member. The sleeve window is formed to extend in a direction parallel to the axial direction of the connecting shaft, and the plurality of spline balls are arranged in the sleeve window so as to form a row by being adjacent to each other so as to be in contact with each other.

[0016] The inner race may have a through hole, and one end of the connecting shaft may be movably inserted into the through hole. The outer spline groove may be formed on the inner surface of the inner race forming the through hole, and the inner spline groove may be formed on the outer surface of the connecting shaft so as to face the outer spline groove.

[0017] The outer race may have a coupling side and an open side, and the connecting shaft may be configured to perform a moving-out behavior moving away from the coupling side and a moving-in behavior moving toward the coupling side through the ball spline coupling structure. The ball spline coupling structure may include a first movement limiting portion provided at one end of the inner race to limit a movement of the spline ball during the moving-out behavior of the connecting shaft, a second movement limiting portion provided at the end of the connecting shaft to limit a movement of the spline ball during the moving-out behavior of the connecting shaft, and a third movement limiting portion provided at the other end of the inner race to limit a movement of the spline ball during the moving-in behavior of the connecting shaft.

[0018] The outer race may have a coupling side and an open side, and the connecting shaft may be configured to perform a moving-out behavior moving away from the coupling side and a moving-in behavior moving toward the coupling side through the ball spline coupling structure. The ball spline coupling structure may include a first movement limiting portion provided at one end of the inner race to limit the behavior of the spline ball during the moving-out behavior of the connecting shaft, a second movement limiting portion provided at the end of the connecting shaft to limit the behavior of the spline ball during the moving-out behavior of the connecting shaft, and a third movement limiting portion provided at the other end of the inner race to limit the behavior of the spline ball during the moving-in behavior of the connecting shaft. The first to third movement limiting portions may be configured to limit the behavior of the spline ball by directly contacting the spline ball without contacting the sleeve member.

[0019] The above connecting shaft may have a solid structure.

[0020] The outer ball track may include a first outer ball track and a second outer ball track, and the inner ball track may include a first inner ball track paired with the first outer ball track and a second inner ball track paired with the second outer ball track. The pair of the first outer ball track and the first inner ball track and the pair of the second outer ball track and the second inner ball track may be configured to have opening angles in opposite directions when in a non-cut state.

[0021] The above torque transmission balls can be provided in eight pieces.

[0022] 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 outer race and the inner race are configured to be able to implement an angular function that causes a relative angular displacement with respect to each other. The inner race is connected to the connecting shaft through a ball spline coupling structure so as to be able to implement a length displacement function due to a relative displacement along the axial direction of the connecting shaft. The outer race and the inner race are configured to enable axial relative displacement due to a clearance between the outer race and the inner race.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] Figure 2 is a perspective view of a constant velocity joint according to an embodiment of the present invention.

[0028] Figure 3 is a front view of a constant velocity joint according to an embodiment of the present invention.

[0029] Figure 4 is a cross-sectional view taken along line AA of Figure 3.

[0030] Figure 5 is a cross-sectional view taken along line BB of Figure 3.

[0031] Figure 6 is a partial cross-sectional view of a constant velocity joint according to an embodiment of the present invention.

[0032] 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.

[0033] Fig. 8 is a cross-sectional view of an outer race of a constant velocity joint according to an embodiment of the present invention.

[0034] Figure 9 is a perspective view of a ball cage of a constant velocity joint according to an embodiment of the present invention.

[0035] Fig. 10 is a side view of an inner race according to an embodiment of the present invention.

[0036] Fig. 11 is a cross-sectional view taken along line CC of Fig. 10.

[0037] Fig. 12 is a perspective view of a sleeve of a constant velocity joint according to an embodiment of the present invention.

[0038] Fig. 13 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.

[0039] Fig. 14 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.

[0040] Fig. 15 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.

[0041] Fig. 16 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.

[0042] FIG. 17 is a drawing showing a state in which an inner race is axially displaced relative to an outer race toward the mating side in a constant velocity joint according to an embodiment of the present invention.

[0043] FIG. 18 is a drawing showing a state in which an inner race is axially displaced relative to an outer race toward the open side in a constant velocity joint according to an embodiment of the present invention.

[0044] Fig. 19 is a drawing comparatively showing the axial friction load of a constant velocity joint according to an embodiment of the present invention and a conventional constant velocity joint.

[0045] Figure 20 is a graph showing the outer diameter of the outer race for securing optimal durability performance according to the number of torque transmitting balls, i.e., the number of outer and inner ball tracks.

[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] The outer race (21) forms outer ball tracks (25, 26) on the inner surface, and 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, eight torque transmission balls (24) may be provided, and the eight torque transmission balls (24) may be arranged at equal intervals along the circumferential direction. The number of torque transmission balls (24) is not limited thereto, and may be variously changed to six, ten, etc. It is particularly preferable that the number of torque transmitting balls (24) is eight. Fig. 20 is a graph showing the outer diameter of the outer race for securing optimal durability performance according to the number of torque transmitting balls, i.e., the number of outer and inner ball tracks. At this time, the outer diameter of the outer race according to the number of torque transmitting balls was calculated based on the value that optimizes the Hertzian contact stress, which is a theoretical calculation value of durability performance. As a result, it can be seen that the outer diameter of the outer race can be made the smallest when the number of torque transmitting balls is eight. This is because when the number of torque transmitting balls exceeds eight, the internal dimensions must be increased to satisfy the Hertzian contact stress, which results in the adverse effect of increasing the outer diameter of the outer race.

[0057] Referring to FIGS. 3 and 9, the ball cage (23) may be interposed between the inner surface of the outer race (21) and the outer 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 surface and the inner surface of the ball cage (23) may each be formed as a spherical surface.

[0058] 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 an opening angle is generally known in the technical field to which the present invention belongs, and may mean an angle formed between the central trajectory of a ball moving on an outer ball track and the central trajectory of a ball moving on an 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.

[0059] The constant velocity joint (13) according to an 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 (X) of the drive shaft (10), i.e., the axial direction (X) of the connecting shaft (11).

[0060] 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).

[0061] 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.

[0062] Fig. 10 is a side view of an inner race according to an embodiment of the present invention, and Fig. 11 is a cross-sectional view taken along line CC of Fig. 10. The inner race (22) forms a through hole (31) extending in the axial direction, and an inner ball track (27, 28) in the form of a sunken groove is formed on the outer circumferential surface of the inner race (22).

[0063] 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 illustrated in FIG. 11, 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).

[0064] Fig. 12 is a perspective view of a sleeve of a constant velocity joint according to an embodiment of the present invention, and Fig. 13 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. 12 and 13, 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).

[0065] Referring to FIGS. 11, 12, and 13, 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 contact 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. 14, 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.

[0066] In addition, in the embodiment of the present invention, since a plurality of spline balls (44) forming a row are accommodated in a single elongated sleeve window (45) at the same time, contact is made between the spline balls (44) during sliding and / or rolling behavior of the spline balls (44), which leads to friction reduction. FIG. 19 is a drawing showing the results of an axial friction test in a case where a plurality of spline balls (44) are accommodated in a single sleeve window (45) as in the embodiment of the present invention (illustrated by a solid line) and a comparative example (illustrated by a dotted line) in which each spline ball is independently accommodated in a different sleeve window. As illustrated in FIG. 19, it was found that the axial friction load was significantly reduced in the embodiment of the present invention.

[0067] FIG. 15 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. 16 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. 15), it is located in the state of FIG. 15, 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. 16), it is located in the state of FIG. 16. Fig. 15 illustrates a state in which the movement in the moving-out direction is maximum, and Fig. 16 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 to be the same as the corresponding length displacement amounts illustrated in Fig. 14. Through this ball spline coupling structure (40), a drive shaft having a determined total length displacement amount (=L1+L2) can be implemented.

[0068] 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 15, 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 from 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. 15, 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.

[0069] Meanwhile, referring to FIGS. 6 and 16, 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 far as possible in the moving-in direction as shown in FIG. 16, 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.

[0070] As illustrated in FIGS. 15 and 16, 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.

[0071] Fig. 17 is a drawing showing a state in which an inner race is axially relatively displaced toward a mating side with respect to an outer race in a constant velocity joint according to an embodiment of the present invention, and Fig. 18 is a drawing showing a state in which an inner race is axially relatively displaced toward an open side with respect to an outer race in a constant velocity joint according to an embodiment of the present invention. According to an embodiment of the present invention, a clearance is configured to exist between the inner surface of the outer race (21) and the outer surface of the ball cage (23) and between the inner surface of the ball cage (23) and the outer surface of the inner race (22), and the axial relative displacement between the outer race (21) and the inner race (22) is configured to be possible by this clearance. For example, FIG. 17 illustrates a state in which the inner race (22) is relatively displaced by a length (S1) set from the joint center plane (P) to the engagement side of the outer race (21), and FIG. 18 illustrates a state in which the inner race (22) is relatively displaced by a length (S2) set from the joint center plane (P) to the open side of the outer race (21). By setting an appropriate clearance and thereby configuring the axial relative displacement between the outer race (21) and the inner race (22) to be possible, some of the required axial displacement can be covered by the relative displacement of the outer race (21) and the inner race (22), and thereby the maximum axial displacement of the ball spline coupling structure (40) can be reduced.

[0072] 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 outer race and the above inner race are configured to implement an angle function that causes a displacement of the relative angle with respect to each other, The above inner race is 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 A constant velocity joint including 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.

2. 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 connecting shaft in the non-cut state of the constant velocity joint.

3. In paragraph 1, The above torque transmitting ball is a constant velocity joint equipped with eight balls.

4. In paragraph 1, The above outer ball track includes a first outer ball track and a second outer ball track, The inner ball track comprises a first inner ball track paired with the first outer ball track and a second inner ball track paired with the second outer ball track, A constant velocity joint in which the pair of the first outer ball track and the first inner ball track and the pair of the second outer ball track and the second inner ball track are configured to have opening angles in opposite directions in a non-cut state.

5. In paragraph 1, A constant velocity joint in which the outer race and the inner race are configured to enable axial relative displacement by a gap between the outer race and the inner race.

6. 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 outer race and the above inner race are configured to implement an angle function that causes a displacement of the relative angle with respect to each other, The above inner race is 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 sleeve window is formed to extend long in a direction parallel to the axis of the above connecting shaft, A drive shaft in which the plurality of spline balls are arranged in a row in the sleeve window so as to be adjacent to each other and in contact with each other.

7. In paragraph 6, The above inner race has a through hole, One end of the above connecting shaft is movably inserted into the through hole, The above outer spline groove is formed on the inner surface of the inner race forming the through hole, A drive shaft in which the inner spline groove is formed on the outer surface of the connecting shaft so as to face the outer spline groove.

8. In paragraph 6, The above outer race has a joining side and an open side, The above connecting shaft is configured to perform a moving-out behavior moving away from the coupling side and a moving-in behavior moving toward the coupling side through the ball spline coupling structure. The above ball spline joint structure A first movement limiting member provided at one end of the inner race to limit the movement of the spline ball during the moving-out movement of the connecting shaft; A second movement limiting member provided at the end of the connecting shaft so as to limit the movement of the spline ball during the moving-out movement of the connecting shaft, and A drive shaft including a third movement limiter provided on the other end of the inner race so as to limit movement of the spline ball during the moving-in movement of the connecting shaft.

9. In paragraph 6, The above outer race has a joining side and an open side, The above connecting shaft is configured to perform a moving-out behavior moving away from the coupling side and a moving-in behavior moving toward the coupling side through the ball spline coupling structure. The above ball spline joint structure A first movement limiting member provided at one end of the inner race to limit the movement of the spline ball during the moving-out movement of the connecting shaft; A second movement limiting member provided at the end of the connecting shaft so as to limit the movement of the spline ball during the moving-out movement of the connecting shaft, and Including a third movement limiter provided on the other end of the inner race so as to limit the movement of the spline ball during the moving-in movement of the connecting shaft; A drive shaft wherein the first to third movement limiting members are configured to limit movement of the spline ball by directly contacting the spline ball without contacting the sleeve member.

10. In paragraph 6, The above connecting shaft is a drive shaft having a solid structure.

11. In paragraph 6, The above outer ball track includes a first outer ball track and a second outer ball track, The inner ball track comprises a first inner ball track paired with the first outer ball track and a second inner ball track paired with the second outer ball track, A drive shaft wherein the pair of the first outer ball track and the first inner ball track and the pair of the second outer ball track and the second inner ball track are configured to have opening angles in opposite directions in a non-cut state.

12. In paragraph 6, A drive shaft having eight of the above torque transmitting balls.

13. 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 outer race and the above inner race are configured to implement an angle function that causes a displacement of the relative angle with respect to each other, The above inner race is 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, A drive shaft in which the outer race and the inner race are configured to enable axial relative displacement by a clearance between the outer race and the inner race.

Images