Face spline structure, and power transmission device including drive shaft and wheel hub assembly coupled to each other via face spline structure

Abstract

The present invention relates to a face spline structure, which is used to transmit driving force to a vehicle, and a power transmission device, which includes a drive shaft and a wheel hub assembly coupled to each other via the face spline structure. The face spline structure includes a first face spline and a second face spline that engage with each other to enable the transmission of rotational power. A first gap between a peak portion of the first face spline and a root portion of the second face spline engaging therewith and a second gap between a peak portion of the second face spline and a root portion of the first face spline engaging therewith each fall within a range of 0.2 mm to 0.7 mm.

Description

A power transmission device having a drive shaft and a wheel hub assembly that are coupled to each other through a face spline structure and a face spline structure.

[0001] The present disclosure relates to a power transmission device including a face spline structure used to transmit driving force of a vehicle and a drive shaft and a wheel hub assembly coupled to each other by the face spline structure.

[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 absorb the various directional displacements generated during vehicle operation while transmitting rotational driving force. They can be implemented in various forms, such as a zebra joint.

[0003] The constant velocity joint can be connected to a wheel hub to transmit power, and the constant velocity joint and the wheel hub are typically connected to each other through a spline structure to rotate together.

[0004] It is common to connect the constant velocity joint and the wheel hub through splines formed to extend axially on the constant velocity joint, but recently, a method has been introduced to dynamically connect the constant velocity joint and the wheel hub through splines formed on a surface perpendicular to the axial direction of the constant velocity joint, the so-called face spline. In the method using the face spline, the constant velocity joint and the wheel hub are connected to each other so as to rotate together through face splines formed on each of the surfaces facing each other.

[0005] In this type of coupling utilizing face splines, teeth formed on a plane perpendicular to the axial direction of the wheel hub mesh with the constant velocity joint of the drive shaft. When the constant velocity joint and the face spline of the wheel hub are combined, the peak and root of the teeth are in contact, which can cause wear on the tooth surfaces during driving, adversely affecting NVH.

[0006] 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 prior art in the field to which this technology belongs.

[0007] <Prior Art Literature>

[0008] - Republic of Korea Patent Publication No. 10-1960098

[0009] - Republic of Korea Patent Publication No. 10-2001883

[0010] - Republic of Korea Patent Publication No. 10-1573923

[0011] - Republic of Korea Patent No. 10-1696907

[0012] The problem to be solved by the present invention is to provide a method for minimizing wear of a constant velocity joint of a drive shaft and a face spline of a wheel hub and increasing durability.

[0013] 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.

[0014] A face spline structure according to an embodiment of the present invention includes a first face spline and a second face spline that mesh with each other to enable transmission of rotational power. A first gap between a peak portion of the first face spline and a root portion of the meshed second face spline and a second gap between a peak portion of the second face spline and a root portion of the meshed first face spline are each in a range of 0.2 mm to 0.7 mm.

[0015] The first interval and the second interval may be equal to each other.

[0016] The first gap and the second gap may be configured to have a minimum of 2 mm or more when the first and second face splines wear out.

[0017] The ratio of the tooth height of the first face spline to the tooth height of the second face spline may fall within a range of 1.0 to 1.2.

[0018] In a state where the first and second face splines are meshed with each other, at a half point of the tooth height of the second face spline, the tooth thickness of the first face spline can be formed to be greater than the inter-tooth distance of the second face spline.

[0019] In a state where the first and second face splines are meshed with each other, at a half point of the tooth height of the second face spline, a ratio of the tooth thickness of the first face spline to the tooth distance of the second face spline may fall within a range of 1 to 1.2.

[0020] The first face spline and the second face spline may each include an inclined surface connecting the peak portion and the root portion, and the first face spline and the second face spline may be configured to transmit the rotational power through contact of the inclined surfaces.

[0021] A power transmission device according to an embodiment of the present invention includes a drive shaft including a constant velocity joint having a first face spline; and a wheel hub assembly including a wheel hub having a second face spline that engages the first face spline to enable transmission of rotational power. A first gap between a peak portion of the first face spline and a root portion of the second face spline that engages the first face spline and a second gap between a peak portion of the second face spline and a root portion of the first face spline that engages the first face spline are each in a range of 0.2 mm to 0.7 mm.

[0022] According to the present invention, wear of the constant velocity joint of the drive shaft and the face spline of the wheel hub can be minimized and durability can be increased. In particular, contact between the interlocking peak and root portions can be prevented, thereby preventing wear and increasing durability.

[0023] 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.

[0024] 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.

[0025] FIG. 1 is a perspective view of a drive shaft to which a spline structure according to an embodiment of the present invention is applied.

[0026] FIG. 2 is a perspective view showing a power transmission device that is a combination of a drive shaft and a wheel hub assembly to which a face spline structure is applied according to an embodiment of the present invention.

[0027] FIG. 3 is an exploded perspective view of a drive shaft and wheel hub assembly to which a face spline structure according to an embodiment of the present invention is applied.

[0028] FIG. 4 is a cross-sectional view showing a state in which the first and second face splines of the face spline structure according to an embodiment of the present invention are engaged.

[0029] FIG. 5 is a drawing for explaining a change in the gap between the peak portion and the root portion due to wear of the inclined surface of the face spline structure according to an embodiment of the present invention.

[0030] FIG. 6 is a drawing for explaining the relationship between the tooth heights of interlocking teeth of a face spline structure according to an embodiment of the present invention.

[0031] FIG. 7 is a drawing for explaining the relationship between the tooth thickness and tooth spacing of teeth that mesh with each other in a face spline structure according to an embodiment of the present invention.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] Fig. 1 is a perspective view of a drive shaft to which a spline structure is applied according to an embodiment of the present invention. Fig. 2 is a perspective view showing a combination of a drive shaft to which a face spline structure is applied according to an embodiment of the present invention and a wheel hub, and Fig. 3 is an exploded perspective view of the drive shaft to which a face spline structure is applied according to an embodiment of the present invention and a wheel hub in an exploded state. Fig. 2 illustrates a constant velocity joint (10) of a drive shaft and a wheel hub assembly (20) in a partially cut state, and Fig. 3 illustrates a wheel hub assembly (20) in a partially cut state.

[0037] Referring to FIGS. 1 to 3, a constant velocity joint (10) to which a face spline structure according to an embodiment of the present invention can be applied may be a constant velocity joint of a type called a Rzeppa joint, and includes an outer joint member (12), an inner joint member (13) disposed within the outer joint member (12), a plurality of power transmission balls (14) disposed between the outer joint member (12) and the inner joint member (13), and a ball cage (15) accommodating the plurality of power transmission balls (14). The power transmission balls (14) may be disposed in ball grooves provided in the outer joint member (12) and the inner joint member (13), respectively, so as to transmit the rotational power of the inner joint member (13) to the outer joint member (12). A connecting shaft (16) is fastened to the inner joint member (13) so as to rotate together with the inner joint member (13). A constant velocity joint (10) may be connected to one end of a connecting shaft (16), and another constant velocity joint (not shown) may be connected to the other end of the connecting shaft (16). Typically, a power transmission device including a connecting shaft (16) and a pair of constant velocity joints connected to both ends thereof is referred to as a drive shaft.

[0038] The outer joint member (12) may have a cup shape with a U-shaped cross-section with one side open, and the inner joint member (13) is arranged in the inner space of the outer joint member (12). A boot (17) may be respectively fastened to the open end of the outer joint member (12) and the connecting shaft (16). The components and operating principles of this constant velocity joint (10) are self-evident to those skilled in the art, and therefore, a detailed description thereof will be omitted.

[0039] For example, a wheel hub assembly (20) includes a wheel hub (21) and a rolling bearing (22). The wheel hub (21) has a substantially cylindrical shape, and the rolling bearing (22) rotatably supports the wheel hub (21). The rolling bearing (22) may include an inner ring (23) that is axially fitted and fastened to an outer surface of the wheel hub (21), an outer ring (24) that is fixedly fastened to a fixed body of the vehicle, such as a body or a knuckle, while being positioned radially outside the inner ring (23), and a ball-shaped rolling element (25) that is interposed between the inner ring (23) and the outer ring (24) or between the wheel hub (21) and the outer ring (24). As illustrated in FIGS. 2 and 3, a plurality of rolling elements (25) may be arranged in two rows.

[0040] A fastening bolt (26) fastens the wheel hub (21) and the outer joint member (12) to each other in an axially fixed manner. The outer joint member (12) may include a shaft portion (121), a shoulder portion (122), and a mouth portion (123), and the fastening bolt (26) may be fastened to the shaft portion (121). Meanwhile, the wheel hub (21) and the outer joint member (12) each have face splines (101, 102) and are fastened to each other so as to rotate together through the engagement of the face splines (101, 102).

[0041] The face spline (101) of the outer joint member (12) can be formed on the outer circumferential surface of the shoulder portion (122) to face the wheel hub (21). In addition, the face spline (102) of the wheel hub (21) is formed on a surface facing the face spline (101) of the outer joint member (12). Since the outer joint member (12) and the wheel hub (21) are rotationally constrained and fastened to each other through the face splines (101, 102), the wheel hub (21) rotates by the rotation of the outer joint member (12). As a result, the rotational power of the constant velocity joint (10) can be transmitted to the wheel hub (21).

[0042] Fig. 4 is a cross-sectional view showing a state in which first and second face splines of a face spline structure according to an embodiment of the present invention are engaged. In Fig. 4, the first face spline (101) may be a face spline formed on an outer joint member (12) of a constant velocity joint (10), and the second face spline (102) may be a face spline formed on a wheel hub (21) of a wheel hub assembly (20).

[0043] The first face spline (101) and the second face spline (102) may have similar shapes. For example, the teeth of the first face spline (101) may include a root portion (101a), a peak portion (101b), and an inclined surface (101c) connecting the root portion (101a) and the peak portion (101b). Similarly, the teeth of the second face spline (102) may include a root portion (102a), a peak portion (102b), and an inclined surface (102c) connecting the root portion (102a) and the peak portion (102b). The first face spline (101) and the second face spline (102) are inserted so that the peak portions (101b, 102b) are close to the opposite root portions (101a, 102a), and at least a portion of the inclined surfaces (101c, 102c) are in surface contact with each other in the interlocked state. At this time, the first face spline (101) and the second face spline (102) are configured so that the peak portions (101b, 102b) do not touch the facing root portions (101a, 102a).

[0044] According to an embodiment of the present invention, referring to FIG. 4, a gap (G1) is formed between a peak portion (101b) of a first face spline (101) and a root portion (102a) of a second face spline (102), and a gap (G2) is formed between a peak portion (102b) of the second face spline (102) and a root portion (101a) of the first face spline (101). Here, the gaps (G1, G2) may each fall within a range of 0.2 mm to 0.7 mm. In addition, the gaps (G1, G2) may be equal to each other. Here, the values ​​of the gaps (G1, G2) may be nominal values.

[0045] As the vehicle is driven, wear occurs on the inclined surfaces (101c, 102c) that come into contact with each other, and as the wear progresses, the gap (G1, G2) between the peak portions (101b, 102b) and the root portions (101a, 102a) that face each other decreases. In an embodiment of the present invention, the gap (G1, G2) between the peak portions (101b, 102b) and the root portions (101a, 102a) that face each other is configured to be secured to a minimum limit value, for example, 0.2 mm or more, as the wear progresses. Fig. 5 shows a relationship for calculating the amount of decrease in the gap (G1) between the peak portions (101b) and the root portions (102a) due to wear of the inclined surfaces (101c, 102c). Referring to FIG. 5, the amount of decrease (y) in the gap (G1) between the peak portion (101b) and the root portion (102a) can be calculated from the amount of wear (x) of the inclined surfaces (101c, 102c) of the teeth and the inclination angle (α) of the inclined surfaces (101c, 102c) by the following mathematical expression 1.

[0046]

[0047] For example, when the inclination angle (α) of the inclined surface (101c, 102c) is 27.5 degrees, the decrease amount (y) of the gap (G1) between the peak portion (101b) and the root portion (102a) according to the wear amount (x) of the inclined surface (101c, 102c) can be calculated as the value shown in Table 1 below by the above mathematical expression 1.

[0048] Wear amount (x, mm) 0.05 0.15 0.25 0.10 0.20 0.30 Reduction amount (y, mm) 0.09 5 0.28 8 0.48 0 0.19 2 0.38 5 0.577

[0049] FIG. 6 is a drawing for explaining the relationship of tooth heights of interlocking teeth of a face spline structure according to an embodiment of the present invention. Referring to FIG. 6, the tooth height (H1) of the tooth profile of the first face spline (101), i.e., the distance between the root portion (101a) and the peak portion (101b), and the tooth height (H2) of the tooth profile of the second face spline (102), i.e., the distance between the root portion (102a) and the peak portion (102b), may be formed differently from each other. For example, the tooth height (H2) of the tooth profile of the second face spline (102) may be greater than the tooth height (H1) of the tooth profile of the first face spline (101) (H2 > H1). As a specific example, the ratio of the tooth height (H2) of the tooth profile of the second face spline (102) to the tooth height (H1) of the tooth profile of the first face spline (101) may be a value falling within a range of 1.0 to 1.2. FIG. 7 is a drawing for explaining the relationship between the tooth thickness and the tooth spacing of the teeth that mesh with each other in the face spline structure according to an embodiment of the present invention. Referring to FIG. 7, at the half point of the tooth height, the tooth thickness (T1) of the first face spline (101) may be formed to be greater than the intertooth distance (D2) of the second face spline (102). Here, the tooth height means the vertical distance between the root and the peak of each tooth. In addition, the half point of the tooth height means the half point of the tooth height of the face spline that forms the valley between the teeth, and in FIG. 7, it corresponds to the half point of the tooth height (H2) at the root portion (102a) of the second face spline (102). As a specific example, at a point halfway between the tooth heights of the second face spline (102), the ratio of the tooth thickness (T1) of the first face spline (101) to the tooth-to-tooth distance (D2) of the second face spline (102) may fall within a range of 1 to 1.2. This can prevent the peak portions and root portions of the teeth that mesh with each other from touching each other.In order to help understanding, Fig. 7 shows the first face spline (101) and the second face spline (102) superimposed before they are meshed with each other. In an actual meshed state, the inclined surfaces of the two tooth shapes come into contact with each other due to deformation of the tooth shapes of the first face spline (101) and the second face spline (102).

[0050] 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. Includes a first face spline and a second face spline that mesh with each other to enable transmission of rotational power, A face spline structure wherein a first gap between a peak portion of the first face spline and a root portion of the second face spline that meshes with it and a second gap between a peak portion of the second face spline and a root portion of the first face spline that meshes with it are each in a range from 0.2 mm to 0.7 mm.

2. In paragraph 1, The above first interval and the above second interval are the same face spline structures.

3. In paragraph 1, A face spline structure in which the first gap and the second gap are configured to have a minimum of 0.2 mm or more when the first and second face splines wear out.

4. In paragraph 1, A face spline structure in which a ratio of the tooth height of the first face spline to the tooth height of the second face spline falls within a range of 1.0 to 1.

2.

5. In paragraph 1, A face spline structure in which, when the first and second face splines are meshed with each other, at a half point of the tooth height of the second face spline, the tooth thickness of the first face spline is formed to be greater than the inter-tooth distance of the second face spline.

6. In paragraph 5, A face spline structure in which, when the first and second face splines are meshed with each other, a ratio of the tooth thickness of the first face spline to the tooth inter-distance of the second face spline at a half point of the tooth height of the second face spline is in a range of 1 to 1.

2.

7. In paragraph 1, The first face spline and the second face spline each include an inclined surface connecting the peak portion and the root portion, A face spline structure in which the first face spline and the second face spline are configured to transmit the rotational power through contact with the inclined surface.

8. A drive shaft including a constant velocity joint having a first face spline; and A wheel hub assembly comprising a wheel hub having a second face spline that engages the first face spline to enable transmission of rotational power; A power transmission device wherein a first gap between a peak portion of the first face spline and a root portion of the second face spline that meshes with it and a second gap between a peak portion of the second face spline and a root portion of the first face spline that meshes with it are each in a range from 0.2 mm to 0.7 mm.

9. In paragraph 8, The above first interval and the above second interval are the same power transmission devices.

10. In paragraph 8, A power transmission device wherein the first gap and the second gap are configured to have a minimum of 0.2 mm or more when the first and second face splines wear out.

11. In Article 8, A power transmission device wherein a ratio of the tooth height of the first face spline to the tooth height of the second face spline is in a range of 1.0 to 1.

2.

12. In paragraph 8, A power transmission device wherein, when the first and second face splines are meshed with each other, at a half point of the tooth height of the second face spline, the tooth thickness of the first face spline is formed to be greater than the tooth inter-distance of the second face spline.

13. In Article 12, A power transmission device wherein, when the first and second face splines are meshed with each other, a ratio of the tooth thickness of the first face spline to the tooth interspace of the second face spline at a half point of the tooth height of the second face spline is in a range of 1 to 1.

2.

14. In paragraph 8, The first face spline and the second face spline each include an inclined surface connecting the peak portion and the root portion, A power transmission device in which the first face spline and the second face spline are configured to transmit the rotational power through contact with the inclined surface.

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