Constant velocity joint

Abstract

A constant velocity joint according to the present invention includes: a housing having three first guide grooves and three second guide grooves; a first spider including a first hub and three first journals, each of which protrudes radially outward from the first hub; three first roller assemblies which operate as a medium for transmitting rotational power between the first journals and the housing; a first torque transmission shaft fastened to the first hub; a first spring for elastically supporting the first spider and the first torque transmission shaft fastened to each other with respect to the housing; a second spider including a second hub and three second journals, each of which protrudes radially outward from the second hub; three second roller assemblies which operate as a medium for transmitting rotational power between the second journals and the housing; a second torque transmission shaft fastened to the second hub; and a second spring for elastically supporting the second spider and the second torque transmission shaft fastened to each other with respect to the housing.

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, used to transmit power in an automobile, is a device that transmits rotational power at a constant velocity. Typically, a constant velocity joint is part of a so-called driveshaft, which transmits power generated by a vehicle's drivetrain, such as a transmission in an internal combustion engine vehicle or a motor in an electric vehicle, to the wheels at a constant velocity. The driveshaft actively responds to the steering of the wheels or vibrations or shocks from the road surface, transmitting power while minimizing power loss. A driveshaft typically includes an inboard joint that receives power from the transmission or motor, an outboard joint that transmits rotational power to the wheels, and an intermediate shaft that connects the inboard and outboard joints.

[0003] Conventional drive shafts have long axial lengths due to the constant velocity joints attached to each end of the intermediate shaft, which poses space constraints for installation. In particular, in a full-scale electric vehicle platform, a motor may be installed at each wheel, reducing the gap between the motor and the wheel, making conventional drive shafts difficult to install. Therefore, a short constant velocity joint with excellent torque transmission efficiency is required. U.S. Patent No. 7,591,729 describes a double constant velocity joint consisting of two constant velocity joints. However, structural improvements and increased efficiency are needed.

[0004] 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.

[0005] The problem to be solved by the present invention is to provide a constant velocity joint that is short in length but has excellent torque transmission efficiency.

[0006] 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.

[0007] A constant velocity joint according to an embodiment of the present invention comprises: a housing having three first guide grooves and three second guide grooves arranged along a circumferential direction; a first spider including a first hub disposed within the housing and three first journals each protruding radially outward from the first hub and disposed in the first guide grooves; three first roller assemblies each fastened to the first journal and operating as a medium for transmitting rotational power between the first journal and the housing; a first torque transmission shaft fastened to the first hub so as to rotate together with the first spider; a first spring elastically supporting the first spider and the first torque transmission shaft, which are fastened to each other, with respect to the housing; a second spider including a second hub disposed within the housing and three second journals each protruding radially outward from the second hub and disposed in the first guide grooves; three second roller assemblies each fastened to the second journal and operating as a medium for transmitting rotational power between the second journal and the housing; A second torque transmission shaft coupled to the second hub so as to rotate together with the second spider; and a second spring elastically supporting the second spider and the second torque transmission shaft coupled to each other with respect to the housing.

[0008] The first spider and the second spider may be arranged on both sides of the longitudinal direction of the housing, and the first and second springs may be arranged in a compressed state between the first spider and the second spider to urge the first spider and the first torque transmission shaft, which are fastened to each other, and the second spider and the second torque transmission shaft, which are fastened to each other, toward the outside of the housing.

[0009] The first spider and the first torque transmitting shaft, which are coupled to each other, and the second spider and the second torque transmitting shaft, which are coupled to each other, may be configured to be movable along the longitudinal direction of the housing, and the first and second springs may be configured to maintain a compressed state over the entire stroke range of the first spider and the first torque transmitting shaft, which are coupled to each other, and the second spider and the second torque transmitting shaft, which are coupled to each other.

[0010] The first and second spiders may be aligned in the same direction along the circumferential direction.

[0011] The first and second spiders may be aligned at a predetermined angle along the circumferential direction. The predetermined angle may be a value within the range of 55 degrees to 65 degrees.

[0012] A constant velocity joint according to another embodiment of the present invention may further include a spring plate for supporting the first and second springs.

[0013] The spring plate may be configured to be detachable from the housing.

[0014] The above spring plate can be fastened to a protruding jaw or a recessed groove provided in the housing.

[0015] A constant velocity joint according to another embodiment of the present invention may further include first and second spring caps respectively disposed between the first and second springs and the first and second torque transmission shafts. The ends of the first and second torque transmission shafts may be formed as convex curved surfaces, and the first and second spring caps may each include concave curved surfaces that contact the ends of the first and second torque transmission shafts.

[0016] The first and second torque transmission shafts and the first and second spring caps may be configured to make spherical contact.

[0017] The first and second springs may have any one of a cylindrical, conical, spherical, and single-piece shape.

[0018] According to the present invention, by arranging two spiders within a single housing to implement two tripod constant velocity joints and supporting the spiders by springs, the overall length of the constant velocity joint can be reduced and the efficiency can be improved.

[0019] 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.

[0020] Figure 1 is a perspective view of a constant velocity joint according to an embodiment of the present invention.

[0021] Figure 2 is a cross-sectional view taken along line II-II of Figure 1.

[0022] Figure 3 is a cross-sectional view taken along line Ⅲ-Ⅲ of Figure 1.

[0023] Figure 4 is a cross-sectional view of a constant velocity joint according to another embodiment of the present invention.

[0024] FIG. 5 is a perspective view of a portion of an outer joint member of a constant velocity joint according to an embodiment of the present invention.

[0025] FIG. 6 is a perspective view of a portion of an outer joint member of a constant velocity joint according to another embodiment of the present invention.

[0026] Fig. 7 is a drawing showing a spring and a spring plate of a constant velocity joint according to an embodiment of the present invention.

[0027] FIG. 8 is a drawing showing a spring and a spring plate of a constant velocity joint according to another embodiment of the present invention.

[0028] FIG. 9 is a drawing showing a torque transmission shaft, a spider, and a spring cap connected to each other of a constant velocity joint according to an embodiment of the present invention.

[0029] Fig. 10 is a partial cross-sectional view of a constant velocity joint according to an embodiment of the present invention.

[0030] Fig. 11 is a drawing showing examples of springs of a constant velocity joint according to an embodiment of the present invention.

[0031] Fig. 12 is a cross-sectional view showing the maximum discharge state of the torque transmission shaft and spider connected to each other of the constant velocity joint according to an embodiment of the present invention.

[0032] Fig. 13 is a cross-sectional view showing the maximum insertion state of the torque transmission shaft and spider connected to each other in a constant velocity joint according to an embodiment of the present invention.

[0033] Figure 14 is a graph comparatively showing the efficiency of a constant velocity joint according to an embodiment of the present invention and a conventional constant velocity joint.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] In describing the components of the present invention, when it is described that a component is “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 another component may also be “connected,” “coupled,” or “connected” between each component.

[0038] Fig. 1 is a perspective view of a constant velocity joint according to an embodiment of the present invention, Fig. 2 is a cross-sectional view taken along line II-II of Fig. 1, and Fig. 3 is a cross-sectional view taken along line III-III of Fig. 1. Referring to Figs. 1 to 3, a constant velocity joint (10) according to an embodiment of the present invention includes two constant velocity joints. The constant velocity joint (10) includes one outer joint member, i.e., a housing (11), and two inner joint members, i.e., first and second spiders (12, 13).

[0039] The housing (11) is used in common for two constant velocity joints, and the first and second spiders (12, 13) are arranged facing each other. Two torque transmission shafts, i.e., the first and second torque transmission shafts (15, 16), are respectively fastened to the spiders (12, 13). For example, the first torque transmission shaft (15) may be connected to a transmission of an automobile, and the second torque transmission shaft (16) may be connected to a wheel of the automobile.

[0040] The torque transmission shafts (15, 16) are fastened to the spiders (12, 13) so as to rotate together with the spiders (12, 13). For example, the torque transmission shafts (15, 16) may be fastened to the spiders (12, 13) via a spline structure. As illustrated in FIG. 2, the combination of the first spider (12) and the first torque transmission shaft (15), and the combination of the second spider (13) and the second torque transmission shaft (16) may be arranged to face each other symmetrically. The combination of the first spider (12) and the first torque transmission shaft (15), and the combination of the second spider (13) and the second torque transmission shaft (16) may be configured to be identical to each other in terms of structure and function.

[0041] The housing (11) and the first and second spiders (12, 13) are configured to implement the structure of a tripod constant velocity joint. The housing (11) has a tubular structure and includes three first guide grooves (17) for the first spider (12) and three second guide grooves (18) for the second spider (13).

[0042] Referring to FIGS. 2 and 3, the first spider (12) includes a hub (21) and three first journals (23) protruding radially from the hub (21), each journal (23) being movably arranged in three first guide grooves (17), respectively. Similarly, the second spider (12) includes a hub (25) and three second journals (27) protruding radially from the hub (25), each journal (27) being movably arranged in three second guide grooves (18), respectively. The first and second spiders (12, 13) are configured to be axially movable with respect to the housing (11) and tiltable so as to allow angular displacement with respect to the housing (11).

[0043] The hub (21) of the first spider (12) includes an axially penetrating through hole (24), and a first torque transmission shaft (15) is inserted into and fixed in the through hole (24). Similarly, the hub (25) of the second spider (13) includes an axially penetrating through hole (26), and a second torque transmission shaft (16) is inserted into and fixed in the through hole (26).

[0044] The first roller assembly (31) is connected to the first journal (23), and the second roller assembly (32) is connected to the second journal (27). The first roller assembly (31) functions to mediate power transmission while functioning as a bearing between the housing (11) and the first spider (12). The first roller assembly (31) connected to the first journal (23) is configured to be movable together with the first journal (23) in the longitudinal direction, i.e., in a direction parallel to the axial direction of the housing (11), in the guide groove (17). Similarly, the second roller assembly (32) functions to mediate power transmission while functioning as a bearing between the housing (11) and the second spider (13). The second roller assembly (32) connected to the second journal (27) is configured to be movable together with the second journal (27) in the longitudinal direction, i.e., in a direction parallel to the axial direction of the housing (11), in the guide groove (18). In this way, a sliding type constant velocity joint is implemented that allows axial strokes of the first and second torque transmission shafts (15, 16) to the housing (11).

[0045] The first and second roller assemblies (31, 32) are respectively arranged in the first and second guide grooves (17, 18) of the housing (11) while being fastened to the first and second journals (23, 27), respectively. The roller assemblies (31, 32) fastened to the journals (23, 27) are formed to be movable together with the journals (23, 27) in the longitudinal direction, i.e., in a direction parallel to the axial direction of the housing (11), in the guide grooves (17, 18). Movement of the roller assemblies (31, 32) within the guide grooves (17, 18) enables axial relative movement of the housing (11) and the spider (12, 13). In addition, the roller assembly (31, 32) is fastened to the journal (23, 27) so as to be tiltable with respect to the journal (23, 27), whereby power transmission can be achieved while simultaneously changing the tilt angle of the roller assembly (31, 32) with respect to the journal (23, 27) and linearly moving the journal (23, 27) and the roller assembly (31, 32) in the cut state of the housing (11) and the spider (12, 13). For example, the first roller assembly (31) may include an inner roller (35) arranged along the periphery of the journal (23) and an outer roller (36) arranged on the outer side of the inner roller (35). Similarly, the second roller assembly (32) may include an inner roller (37) arranged along the periphery of the journal (27) and an outer roller (38) arranged on the outer side of the inner roller (37).

[0046] The end (41) of the first torque transmission shaft (15) passing through the first spider (12) is elastically supported by the first spring (43) against the first spring plate (44). Similarly, the end (45) of the second torque transmission shaft (16) passing through the second spider (13) is elastically supported by the second spring (47) against the second spring plate (48). The first and second spring plates (44, 48) can be fixedly installed within the housing (11), and the first and second springs (43, 47) are supported by the first and second spring plates (44, 46), respectively, and are arranged in a compressed state by the ends (41, 45) of the first and second torque transmission shafts (15, 16). At this time, the first and second springs (43, 47) in a compressed state elastically press the first and second torque transmission shafts (15, 16) in a direction that pushes them outward from the housing (11). The first spider (12) and the first torque transmission shaft (15), which are connected to each other, are elastically supported by the first spring (43), and the second spider (13) and the second torque transmission shaft (16), which are connected to each other, are elastically supported by the second spring (47), so that the force generated in the axial direction of the housing (11), the so-called axial force (GAF), can be absorbed by the first and second springs (34, 47).

[0047] One end of the first spring (43) is inserted into a recessed groove (51) provided in the first spring plate (44), and a first spring cap (53) can be fastened to the other end of the first spring (43). The spring cap (53) can include a bottom portion (55) and a side portion (56). The bottom portion (55) is supported by the end (41) of the first torque transmission shaft (15), and the side portion (56) is configured to surround the outer side of the first spring (43). Similarly, one end of the second spring (47) is inserted into a recessed groove (61) provided in the second spring plate (48), and a second spring cap (63) can be fastened to the other end of the second spring (47). The spring cap (63) can include a bottom portion (65) and a side portion (66). The bottom part (65) is supported on the end (45) of the second torque transmission shaft (16), and the side part (66) is configured to wrap around the outside of the second spring (47).

[0048] By means of the above structure, the length of the housing (11) can be reduced while ensuring sufficient stroke of the first and second torque transmission shafts (15, 16).

[0049] To prevent leakage of grease filled inside the housing (11), first and second boots (71, 72) may be provided. The first boot (71) may be fastened to one end of the housing (11) and the first torque transmission shaft (15), respectively, and the second boot (72) may be fastened to the other end of the housing (11) and the second torque transmission shaft (16), respectively. The first and second boots (71, 72) may be diaphragm boots and may be fixed by clamps.

[0050] Fig. 4 is a cross-sectional view of a constant velocity joint according to another embodiment of the present invention. Referring to Fig. 4, spiders (12, 13) are arranged circumferentially and offset within the housing (11) so as to have a predetermined phase difference, i.e., a phase difference of 55 to 65 degrees, in the circumferential direction. This allows the overall length of the constant velocity joint to be reduced and its efficiency to be further improved.

[0051] FIG. 5 is a partial perspective view of an outer joint member of a constant velocity joint according to an embodiment of the present invention, and FIG. 6 is a partial perspective view of an outer joint member of a constant velocity joint according to another embodiment of the present invention. Referring to FIG. 5, a protruding projection (81) for supporting a spring plate (44) may be provided on the inside of a housing (11). The spring plate (44) may be configured in a form that can be separated from the housing (11) and may be installed in the housing (11) while being supported by the protruding projection (81). Meanwhile, referring to FIG. 6, a recessed groove (82) into which a spring plate (44) is inserted may be provided on the inside of a housing (11). The spring plate (44) may be configured in a form that can be separated from the housing (11) and may be installed in the housing (11) while being seated in the recessed groove (82).

[0052] Fig. 7 is a drawing showing a spring and a spring plate of a constant velocity joint according to an embodiment of the present invention, and Fig. 8 is a drawing showing a spring and a spring plate of a constant velocity joint according to another embodiment of the present invention. Referring to Fig. 7, the spring plate (44) may have a recessed groove (51) into which the spring (43) is inserted. Meanwhile, referring to Fig. 8, the spring plate (83) may have a protrusion (84) inserted into the spring (43). The spring (43) can be more firmly supported by the recessed groove (51) or the protrusion (84).

[0053] FIG. 9 is a drawing showing a torque transmission shaft, a spider, and a spring cap connected to each other of a constant velocity joint according to an embodiment of the present invention. Referring to FIG. 9, the end (41) of the first torque transmission shaft (15) may be formed as a convex curved surface, for example, a convex spherical surface, and correspondingly, the bottom (55) of the first spring cap (53) may be formed as a concave curved surface, for example, a concave spherical surface. Similarly, the end (45) of the second torque transmission shaft (16) may be formed as a convex curved surface, and correspondingly, the bottom (65) of the second spring cap (63) may be formed as a concave curved surface.

[0054] Fig. 10 is a partial cross-sectional view of a constant velocity joint according to an embodiment of the present invention, and Fig. 11 is a drawing showing examples of springs of a constant velocity joint according to an embodiment of the present invention. Referring to Fig. 10, a spring (43) in the form of a cylindrical coil spring can elastically support a torque transmission shaft (15). Meanwhile, as illustrated in Fig. 11, the spring (43) may have a shape not only of a cylindrical shape but also of a conical shape (b) whose diameter gradually decreases toward one side, a spherical shape (c) whose diameter is small in the center, and a single-end shape (d) whose diameter is large in the center. The shape of the spring (43) may be selected to avoid interference with other elements or to suit the design of the spring plate.

[0055] Fig. 12 is a cross-sectional view showing the maximum discharge state of the torque transmission shaft and spider connected to each other of the constant velocity joint according to an embodiment of the present invention, and Fig. 13 is a cross-sectional view showing the maximum insertion state of the torque transmission shaft and spider connected to each other of the constant velocity joint according to an embodiment of the present invention. As shown in Figs. 12 and 13, the torque transmission shaft (15) and the spider (12) connected to each other are allowed to move in the direction of the arrows to be discharged from the housing (11) or inserted into the housing (11), and the spring (43) is maintained in a compressed state throughout the entire stroke. That is, as shown in Fig. 12, when the torque transmission shaft (15) and the spider (12) connected to each other are maximally discharged from the housing (11), the spring (43) is configured to be maintained in a compressed state. This can prevent the spring (43) from being separated from the spring plate (44) or the spring cap (53). In addition, as shown in Fig. 13, when the torque transmission shaft (15) and spider (12) are connected to each other and inserted into the housing (11) as far as possible, the spring (43) must be compressed within the allowable load.

[0056] Figure 14 is a graph comparatively showing the efficiency of a constant velocity joint according to an embodiment of the present invention and a conventional constant velocity joint. Referring to Figure 14, it can be seen that the constant velocity joint of the present invention significantly reduces torque loss compared to a conventional constant velocity joint.

[0057] 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. A housing having three first guide grooves and three second guide grooves arranged along the circumferential direction; A first spider including a first hub disposed within the housing and three first journals each protruding radially outward from the first hub and each disposed in the first guide groove; Three first roller assemblies each fastened to the first journal and acting as a medium for transmitting rotational power between the first journal and the housing; A first torque transmitting shaft connected to the first hub so as to rotate together with the first spider; A first spring that elastically supports the first spider and the first torque transmission shaft, which are connected to each other, with respect to the housing; A second spider including a second hub disposed within the housing and three second journals each protruding radially outward from the second hub and each disposed in the first guide groove; Three second roller assemblies each fastened to the second journal and acting as a medium for transmitting rotational power between the second journal and the housing; a second torque transmitting shaft connected to the second hub so as to rotate together with the second spider; and A constant velocity joint including a second spring that elastically supports the second spider and the second torque transmission shaft, which are connected to each other, with respect to the housing.

2. In paragraph 1, The first spider and the second spider are arranged on both sides of the longitudinal direction of the housing, A constant velocity joint in which the first and second springs are arranged in a compressed state between the first spider and the second spider to press the first spider and the first torque transmission shaft, which are connected to each other, and the second spider and the second torque transmission shaft, which are connected to each other, toward the outside of the housing.

3. In paragraph 1, The first spider and the first torque transmission shaft, which are connected to each other, and the second spider and the second torque transmission shaft, which are connected to each other, are configured to be movable along the longitudinal direction of the housing, A constant velocity joint wherein the first and second springs are each configured to maintain a compressed state over the entire stroke range of the first spider and the first torque transmission shaft which are connected to each other and the second spider and the second torque transmission shaft which are connected to each other.

4. In paragraph 1, The first and second spiders are constant velocity joints aligned in the same direction along the circumferential direction.

5. In paragraph 1, The first and second spiders are constant velocity joints that are aligned at a predetermined angle along the circumferential direction.

6. In paragraph 5, The above predetermined angle is a constant velocity joint having a value in the range of 55 to 65 degrees.

7. In paragraph 1, A constant velocity joint further comprising a spring plate for supporting the first and second springs.

8. In paragraph 7, A constant velocity joint in which the spring plate is configured to be detachable from the housing.

9. In paragraph 8, The above spring plate is a constant velocity joint that is fastened to a protruding jaw or a recessed groove provided in the housing.

10. In paragraph 1, Further comprising first and second spring caps respectively disposed between the first and second springs and the first and second torque transmission shafts, The ends of the first and second torque transmission shafts are formed as convex curved surfaces, A constant velocity joint in which the first and second spring caps each include a concave surface that contacts the ends of the first and second torque transmission shafts.

11. In paragraph 10, A constant velocity joint in which the first and second torque transmission shafts and the first and second spring caps are configured to make spherical contact.

12. In paragraph 1, The above first and second springs are constant velocity joints having any one of a cylindrical, conical, spherical, and single-piece shape.

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