Constant velocity joint

Abstract

This constant velocity joint comprises: an outer race; an inner race disposed in the outer race; multiple balls which are arranged between the outer race and the inner race and act as a medium for transmitting rotational power between the outer race and the inner race; a ball cage accommodating the multiple balls; a boot adapter disposed at one side of the outer race; and a ball retainer disposed at the other side of the outer race. The outer race and the boot adapter, and the outer race and the ball retainer are bonded to each other through contact surfaces on which sealant layers are formed; and the sealant layers are formed by pressing pre-sealant patterns applied on the contact surfaces. The contact surfaces have a ten-point average surface roughness (Rz) in the range of 10 to 50 ㎛.

Description

constant velocity joint

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

[0002] A constant velocity joint, 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, a constant velocity joint is designed to transmit the rotational power generated by the vehicle's power source at a constant velocity.

[0003] In general, a ball-type constant velocity joint is configured to transmit rotational power between an outer race and an inner race via balls accommodated in a window of a ball cage, which are arranged between the outer race and the inner race. The balls are arranged in a space formed by an outer ball groove formed on the inner surface of the outer race and an inner ball groove formed on the outer surface of the inner race corresponding to the outer ball groove, and act as a medium for transmitting rotational power between the outer race and the inner race. In this regard, the outer ball groove and the inner ball groove that accommodate the balls can be implemented in various forms, and as one example, a constant velocity joint having an outer ball groove and an inner ball groove that are formed to intersect each other with respect to the longitudinal direction of the joint has been introduced. This type of constant velocity joint is called a cross-groove type constant velocity joint.

[0004] In certain types of cross-groove type constant velocity joints, a ball retainer and a boot adapter are respectively attached to the longitudinal ends of the outer race to accommodate balls. Sealants are applied to the contact surfaces of the outer race and the ball retainer, and the contact surfaces of the outer race and the boot adapter, to enhance bonding performance. The properties of the sealant layer are affected by factors such as the surface roughness of the contact surface of the outer race, the pressure applied during bonding, the pressurized area, and the sealant area. Optimizing these conditions is required to realize optimal sealing properties by the sealant layer.

[0005] 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.

[0006] The problem to be solved by the present invention is to provide a constant velocity joint that can improve the sealing characteristics between an outer race and a boot adapter and between an outer race and a ball retainer.

[0007] 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.

[0008] A constant velocity joint according to an embodiment of the present invention includes an outer race, an inner race disposed within the outer race, a plurality of balls disposed between the outer race and the inner race and acting as a medium for transmitting rotational power between the outer race and the inner race, a ball cage accommodating the plurality of balls, a boot adapter disposed on one side of the outer race, and a ball retainer disposed on the other side of the outer race. The outer race and the boot adapter and the outer race and the ball retainer are joined to each other through a contact surface on which a sealing material layer is formed, and the sealing material layer is formed by pressing a pre-sealing material pattern applied on the contact surface. The contact surface has a 10-point average surface roughness (Rz) in a range of 10 to 50 ㎛.

[0009] The above pre-sealing material pattern can be formed by pressurization using a press jig, and the press jig can be configured to apply a pressure in the range of 1.25 to 2.5 MPa to form the pre-sealing material pattern.

[0010] The ratio of the contact area of ​​the above pre-sealing material pattern to the pressing area of ​​the press jig may be in the range of 10 to 40%.

[0011] The ratio of the area of ​​the sealing layer to the area of ​​the contact surface may be in the range of 50 to 100%.

[0012] The above contact surface can be formed to have the above 10-point average surface roughness (Rz) through one or more of turning, knurling pattern processing, discontinuous dimple pattern processing, or continuous groove pattern processing.

[0013] According to the present invention, the sealing characteristics between the outer race and the boot adapter and between the outer race and the ball retainer can be improved by controlling the surface roughness of the contact surface, the pressure of the press jig, the ratio of the contact area of ​​the pre-sealing material pattern and the pressurized area of ​​the press jig, the ratio of the area of ​​the sealing material layer and the area of ​​the contact surface, etc.

[0014] 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.

[0015] 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.

[0016] FIG. 1 is a perspective view of a drive shaft including a constant velocity joint according to an embodiment of the present invention.

[0017] Figure 2 is a partial cross-sectional view of a constant velocity joint according to an embodiment of the present invention.

[0018] Figure 3 is a front view of a constant velocity joint according to an embodiment of the present invention with the boot, boot adapter, and ball retainer removed.

[0019] FIG. 4 is a drawing showing an outer ball groove and an inner ball groove of a constant velocity joint according to an embodiment of the present invention projected onto a plane.

[0020] Fig. 5 is a perspective view showing the power transmission shaft and boot removed from the constant velocity joint of Fig. 1.

[0021] Figure 6 is a cross-sectional view taken along line AA of Figure 5.

[0022] Figure 7 is an exploded perspective view of the outer race and inner race of a constant velocity joint according to an embodiment of the present invention.

[0023] Figure 8 is an exploded perspective view of a ball cage and a ball of a constant velocity joint according to an embodiment of the present invention.

[0024] Fig. 9 (a) shows the shape of a pre-sealing material pattern formed on a contact surface of a boot adapter of a constant velocity joint according to an embodiment of the present invention, and (b) shows the shape of a sealing material layer formed by pressing.

[0025] Fig. 10 (a) shows a pattern of a pre-sealing material formed on a contact surface of a ball retainer of a constant velocity joint according to an embodiment of the present invention, and (b) shows a shape of a sealing material layer formed by pressing.

[0026] FIG. 11 is a drawing for explaining a process of pressing a sealant pattern applied using a press jig in an embodiment of the present invention.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] FIG. 1 is a perspective view of a constant velocity joint according to an embodiment of the present invention, and FIG. 2 is a partial cross-sectional view of a so-called cross groove type constant velocity joint according to an embodiment of the present invention. FIG. 3 is a perspective view showing the constant velocity joint of FIG. 1 with the power transmission shaft, the boot, the boot adapter, and the ball retainer removed, and FIG. 4 is a drawing showing the outer ball groove and the inner ball groove of the constant velocity joint according to an embodiment of the present invention projected onto a plane. Referring to FIGS. 1 and 2, a constant velocity joint (10) according to an embodiment of the present invention can be connected to a power transmission shaft (101). The constant velocity joint (10) can be fastened to one end of the power transmission shaft (101), and a constant velocity joint (103) can be fastened to the other end of the power transmission shaft (101).

[0032] The constant velocity joint (10) may be a ball-type constant velocity joint that transmits rotational power using a ball. The constant velocity joint (10) includes an outer race (11) and an inner race (21). The outer race (11) has a shape that penetrates in the longitudinal direction and includes first and second outer ball grooves (13, 14) formed on the inner surface. The inner race (21) is arranged in an inner space of the outer race (11) and includes first and second inner ball grooves (23, 24) formed on the outer surface. The first outer ball groove (13) and the first inner ball groove (23) form a pair, and a ball (31) is arranged in a space formed by the pair of the first outer ball groove (13) and the first inner ball groove (23). In addition, the second outer ball groove (14) and the second inner ball groove (24) form a pair, and balls (31) are arranged in the space formed by the pair of the second outer ball groove (14) and the second inner ball groove (24). The balls (31) can be arranged along the circumferential direction, and each ball (31) can be arranged in a window (35) of the ball cage (33). The balls (31) can be arranged along the circumferential direction.

[0033] Referring to FIGS. 3 and 4, the first outer ball groove (13) and the second outer ball groove (14) are inclined in opposite directions with respect to the longitudinal direction, and the first and second outer ball grooves (13, 14) are arranged alternately along the circumferential direction. Similarly, the first inner ball groove (23) and the second inner ball groove (24) are inclined in opposite directions with respect to the longitudinal direction, and the first and second inner ball grooves (23, 24) are arranged alternately along the circumferential direction. At this time, the first outer ball groove (13) and the first inner ball groove (23), which form a pair, are inclined in opposite directions with respect to the longitudinal direction, and the second outer ball groove (14) and the second inner ball groove (24), which form a pair, are inclined in opposite directions with respect to the longitudinal direction. A constant velocity joint having this type of ball groove is known as a cross groove type constant velocity joint.

[0034] Fig. 5 is a perspective view showing the constant velocity joint of Fig. 1 with the power transmission shaft and the boot removed, and Fig. 6 is a rear perspective view of the constant velocity joint of Fig. 5. Referring to Figs. 5 and 6, a boot adapter (41) is fastened to one side of the outer race (11), and a ball retainer (51) is fastened to the other side of the outer race (11). The outer race (11) has a first contact surface (11a) and a second contact surface (11b) on both sides in the longitudinal direction, and the boot adapter (41) and the ball retainer (51) are fastened to the outer race (11) in a state of contacting the first and second contact surfaces (11a, 11b), respectively. The outer race (11) includes a plurality of coupling holes (11c) extending in parallel with the longitudinal direction, and the boot adapter (41) and the ball retainer (51) also include coupling holes (42, 52) formed at corresponding positions, respectively. By inserting and fixing a coupling means such as a coupling rod into the coupling holes (42, 11c, 52), the boot adapter (41), the outer race (11), and the ball retainer (51) can be fixed to the transmission of the vehicle.

[0035] The boot adapter (41) includes a boot fastening portion (43) to which the boot (61) is fastened, and the boot fastening portion (43) may have a roughly hollow cylindrical shape extending along the longitudinal direction of the constant velocity joint (10). As shown in FIGS. 1 and 2, one end of the boot (61) is fixed to the boot fastening portion (43) and the other end is fixed to the power transmission shaft (101). In addition, the boot adapter (41) includes a ball contact portion (45) extending radially outward from one end of the boot fastening portion (43). The ball contact portion (45) forms a contact surface (46) that contacts the first contact surface (11a) of the outer race (11). The ball contact portion (45) can form a free space when the ball (31) is transported longitudinally in the outer and inner ball grooves of the outer race (11) and the inner race (21). The coupling hole (42) described above can be formed in the ball contact surface (46).

[0036] The ball retainer (51) includes a retaining portion (53) for securing a longitudinal transport space for the ball (31) and preventing it from coming off, and a ball contact portion (55) extending radially outward from one end of the retaining portion (53). The ball contact portion (55) forms a contact surface (56) that comes into contact with the second contact surface (11b) of the outer race (11). The coupling hole (52) described above may be formed in the contact surface (56).

[0037] In an embodiment of the present invention, a sealing material is applied to each of the contact surface (46) of the boot adapter (41) and the contact surface (56) of the ball retainer (51), thereby implementing sufficient sealing characteristics for grease sealing between the outer race (11) and the boot adapter (41) and between the outer race (11) and the ball retainer (51).

[0038] First, in an embodiment of the present invention, the 10-point average surface roughness (Rz) value of the surface to which the sealant is applied may fall within the range of 10 to 50 ㎛. At this time, the surface to which the sealant is applied may be the contact surface (46) of the boot adapter (41), the contact surface (56) of the ball retainer (51), or the contact surface (11a, 11b) of the outer race (11). Fig. 9 (a) illustrates the shape of the pre-sealing material pattern (71) formed on the contact surface (46) of the boot adapter (41) of the constant velocity joint, and (b) shows the shape of the sealing material layer (73) obtained by changing the shape of the sealing material pattern (71) by pressurization by a jig. And, in (a) of Fig. 10, a pre-sealing material pattern (81) formed on a contact surface (56) of a ball retainer (51) of a constant velocity joint is shown, and in (b), a shape of a sealing material layer (83) obtained by changing the shape of the sealing material pattern (81) by pressurization by a jig is shown.

[0039] As a result of conducting an actual test, it was confirmed that there was no grease leakage when the surface roughness (Rz) of the contact surface where the sealing layer is formed was in the range of 11 to 25 ㎛. In addition, when a sample with a surface roughness (Rz) of the surface where the sealing material is applied was immersed in water and an air pressure of 0.5, 1.0, and 1.5 bar was applied to conduct an air leakage test, it was confirmed that excellent sealing performance was secured in which no air bubbles were generated in the inflated state of the boot even when an air pressure of 1.5 bar was injected.

[0040] In order to secure the above-mentioned surface roughness, the surface on which the sealant is applied can utilize turning processing, knurling pattern processing, discontinuous dimple pattern processing, continuous groove pattern processing, etc.

[0041] Fig. 11 is a drawing for explaining a process of pressing a pre-sealing material pattern (71 or 81) applied by a press jig (91). The pressing pressure of the press jig (91) may fall within a range of 1.25 to 2.5 MPa. In addition, the ratio of the contact area of ​​the pre-sealing material pattern (71, 81) to the pressing area of ​​the press jig (91) may fall within a range of 10 to 40%.

[0042] Additionally, the ratio of the area of ​​the sealing layer (73, 83) to the area of ​​the contact surface (46, 56) may fall within the range of 50 to 100%.

[0043] 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. Outer race, Inner lace placed within the above outer lace, A plurality of balls arranged between the outer race and the inner race and acting as a medium for transmitting rotational power between the outer race and the inner race, A ball cage for accommodating the above plurality of balls, A boot adapter positioned on one side of the above outer race, and Including a ball retainer arranged on the other side of the above outer race, The above outer race and the above boot adapter and the above outer race and the above ball retainer are joined to each other through a contact surface on which a sealing layer is formed, The above sealant layer is formed by pressing a pre-sealing material pattern applied on the above contact surface, The above contact surface is a constant velocity joint having a 10-point average surface roughness (Rz) in the range of 10 to 50 ㎛.

2. In paragraph 1, The above pre-sealing material pattern is formed by pressurization using a press jig. The above press jig is a constant velocity joint configured to apply a pressure in the range of 1.25 to 2.5 MPa so as to pressurize the above pre-sealing material pattern.

3. In paragraph 2, A constant velocity joint in which the ratio of the contact area of the above pre-sealing material pattern to the pressurized area of the above press jig is in the range of 10 to 40%.

4. In paragraph 3, A constant velocity joint in which the ratio of the area of the sealing layer to the area of the contact surface is in the range of 50 to 100%.

5. In paragraph 1, A constant velocity joint in which the above contact surface is formed to have the 10-point average surface roughness (Rz) through at least one of turning, knurling pattern processing, discontinuous dimple pattern processing, or continuous groove pattern processing.

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