Tripod constant-velocity joint

Abstract

This tripod constant-velocity joint comprises: a housing having three guide grooves; a spider comprising a hub disposed in the housing and three journals protruding radially outward from the hub and arranged in the respective guide grooves; and three roller assemblies acting as intermediaries for transmitting rotational power between the journals and housing. Each guide groove comprises a ceiling surface, and first and second power transmission surfaces on either side of the ceiling surface. Each roller assembly comprises an inner roller and an outer roller disposed on the outer side of the inner roller. The first and second power transmission surfaces allow transmission of power via interaction with the outer surface of the outer rollers. Each outer roller comprises a first tilt-limiting surface provided on the inside end of the outer surface, and the housing comprises second tilt-limiting surfaces that come in contact with the first tilt-limiting surfaces to limit further tilting of the outer rollers when same are tilted.

Description

Tripod constant velocity joint

[0001] The present disclosure relates to a tripod 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] A tripod constant velocity joint, a type of constant velocity joint, is a sliding type constant velocity joint that can allow angular displacement and axial length displacement, and is mainly used as an inboard joint of a half shaft. A conventional tripod constant velocity joint includes a housing containing three axial guide grooves, a spider containing three radially protruding journals, and three roller assemblies each fastened to the journals.

[0004] To address the problem of generated axial force (GAF) occurring in a tripod constant velocity joint, a tripod constant velocity joint including a roller assembly composed of an outer roller and an inner roller has been proposed. When the constant velocity joint is articulated and operates, the outer roller rotates in rolling contact with the guide groove of the housing. However, if the outer roller tilts in the axial plane of the housing, unnecessary contact occurs on the opposite side of the rolling contact surface of the outer roller and the guide groove, preventing stable rolling motion and generating excessive internal friction. This causes noise and vibration, which deteriorates the NVH performance of the vehicle and causes the problem of shudder, a lateral vibration.

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

[0006] The problem to be solved by the present invention is to provide a tripod constant velocity joint that enables smooth rolling movement by preventing unnecessary contact from occurring on the opposite side of the rolling contact surface of the outer roller and the guide groove due to excessive tilting of the outer roller.

[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 tripod constant velocity joint according to an embodiment of the present invention comprises: a housing having three guide grooves arranged along a circumferential direction; a spider including a hub disposed within the housing and three journals each protruding radially outward from the hub and disposed in the guide grooves; and three roller assemblies each fastened to the journals and acting as a medium for transmitting rotational power between the journals and the housing. The guide grooves include a ceiling surface and first and second power transmission surfaces provided on both sides of the ceiling surface. The roller assembly includes an inner roller disposed to surround the journal and an outer roller disposed on an outer side of the inner roller. The first and second power transmission surfaces are configured to transmit power by interaction with an outer circumferential surface of the outer roller. The outer roller includes a first tilting limiting surface provided on an inner end of an outer surface, and the housing includes a second tilting limiting surface that contacts the first tilting limiting surface when the outer roller is tilted to limit further tilting of the outer roller.

[0009] The above outer roller may be configured to contact the ceiling surface of the other side of the outer surface when tilted while one side of the outer surface is in contact with the first power transmission surface.

[0010] The first tilting restriction surface may have a convex curved shape, and the second tilting restriction surface may have a flat shape.

[0011] The first tilting restriction surface may have a flat shape, and the second tilting restriction surface may have a convex curved shape.

[0012] The first tilting restriction surface and the second tilting restriction surface may each have a flat shape.

[0013] A preset gap may exist between the first tilting restriction surface and the second tilting restriction surface while the outer roller is not tilted and is in close contact with the first power transmission surface.

[0014] The above preset gap may be in the range of 0.005 mm to 0.1 mm.

[0015] The first tilting restriction surface may be provided on each side of the center line of the first and second power transmission surfaces, and the second tilting restriction surface may be provided on each side of the center line of the first and second power transmission surfaces.

[0016] The ratio of the outer diameter of the outer roller to the pitch circle diameter of the housing may be in the range of 0.8 to 0.95.

[0017] The ratio of the radius of curvature of the first tilting restriction surface to the radius of curvature of the outer surface of the outer roller may be in the range of 0.4 to 0.6.

[0018] According to the present invention, by limiting the tilting of the outer roller, unnecessary contact does not occur on the opposite side of the rolling contact surface of the outer roller and the guide groove, thereby enabling smooth rolling movement.

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

[0021] Fig. 2 is a front view of a tripod constant velocity joint according to an embodiment of the present invention.

[0022] FIG. 3 is a partial cross-sectional view of a tripod constant velocity joint according to an embodiment of the present invention.

[0023] FIG. 4 is a drawing for explaining the tilting limitation of the outer roller due to contact between the bottom surface of the guide groove of the tripod constant velocity joint and the outer roller according to an embodiment of the present invention.

[0024] FIG. 5 is a drawing for explaining the tilting limitation of the outer roller due to contact between the side surface of the guide groove of the tripod constant velocity joint and the outer roller according to an embodiment of the present invention.

[0025] FIG. 6a is a drawing showing the shape of a tilting limit surface of a tripod constant velocity joint according to another embodiment of the present invention.

[0026] FIG. 6b is a drawing showing the shape of a tilting limiting surface of a tripod constant velocity joint according to another embodiment of the present invention.

[0027] FIG. 7 is a drawing showing a state in which the outer roller of a tripod constant velocity joint according to an embodiment of the present invention is in close contact with the power transmission surface of the housing and is not tilted.

[0028] FIG. 8 is a drawing showing the side of a guide groove and the shape of an outer roller of a tripod constant velocity joint according to another embodiment of the present invention.

[0029] Figure 9 is a front view of a tripod constant velocity joint according to an embodiment of the present invention.

[0030] Fig. 10 is a graph comparatively showing the force generated due to internal friction of a tripod constant velocity joint according to an embodiment of the present invention and a conventional tripod constant velocity joint.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] FIG. 1 is a perspective view of a tripod constant velocity joint according to an embodiment of the present invention, and FIG. 2 is a front view of a tripod constant velocity joint according to an embodiment of the present invention. FIG. 3 is a partial cross-sectional view of a tripod constant velocity joint according to an embodiment of the present invention. Referring to FIGS. 1 to 3, a tripod constant velocity joint (10) includes a housing (11), a spider (12), and a roller assembly (13). The housing (11) and the spider (12) may be configured to be respectively fastened to a power transmission element, and the roller assembly (13) is configured to be interposed between the housing (11) and the spider (12) to perform a power transmission mediating and bearing function. Here, the housing (11) may be referred to as an outer joint member, and the spider (12) may be referred to as an inner joint member.

[0036] The housing (11) may have a cup shape with one axial side open. Referring to FIGS. 1 to 3, the housing (11) has a central cavity (14) of a roughly cylindrical shape extending in the axial direction, and three guide grooves (15) arranged at equal intervals along the circumference of the central cavity (14) and extending in a direction parallel to the axial direction. Each guide groove (15) may be formed to be recessed radially outward from the central cavity (14).

[0037] A spider (12) is disposed within a housing (11). Referring to FIGS. 1 to 3, the spider (12) includes a hub (16) and three journals (17) that protrude radially outward from an outer surface of the hub (16). The hub (16) is disposed in a central cavity (14) of the housing (11), and the three journals (17) are formed to protrude radially outward from the outer surface of the hub (16), respectively. The three journals (17) are arranged at equal intervals along the circumferential direction on the outer surface of the hub (16) and can be respectively disposed in guide grooves (15) of the housing (11). The spider (12) is 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).

[0038] The hub (16) of the spider (12) forms a through hole (18) extending longitudinally, and an intermediate shaft (not shown) is inserted into the through hole (18). The intermediate shaft is fastened to the hub (16) so as to rotate together with the hub (16), and may be fastened to the spider (12) via, for example, a spline structure.

[0039] Three roller assemblies (13) are respectively fastened to three journals (17). Referring to FIGS. 2 and 3, the roller assemblies (13) are arranged in the guide grooves (15) of the housing (11) while being fastened to the journals (17). The roller assemblies (13) serve as bearings between the housing (11) and the spider (12) and mediate power transmission. The roller assemblies (13) fastened to the journals (17) are formed to be able to move together with the journals (17) in the longitudinal direction, i.e., in a direction parallel to the axial direction of the housing (11), in the guide grooves (15). Movement of the roller assemblies (13) within the guide grooves (15) enables relative axial movement of the housing (11) and the spider (12). In addition, the roller assembly (13) is fastened to the journal (17) so as to be tiltable with respect to the journal (17), whereby power transmission can be achieved while simultaneously changing the tilt angle of the roller assembly (13) with respect to the journal (17) and linearly moving the roller assembly (13) in the cut state of the housing (11) and the spider (12). For example, the roller assembly (13) may include an inner roller (21) arranged along the circumference of the journal (17), an outer roller (23) arranged on the outside of the inner roller (21), a needle bearing (22) interposed between the inner roller (21) and the outer roller (23), and a retaining ring (24) fastened to the outer roller (23) to prevent the inner roller (21) from coming off.

[0040] Referring to Fig. 3, the outer surface of the journal (17) includes a convex surface, and the inner roller (21) may have a cylindrical shape. The outer surface of the outer roller (23) includes a convex surface, and the convex outer surface of the outer roller (23) contacts the housing (11) to transmit torque.

[0041] The guide groove (15) of the housing (11) in which the roller assembly (13) is arranged extends in a direction parallel to the longitudinal axis of the housing (11), i.e., in the depth direction in FIG. 2. The guide groove (15) may be formed by three surfaces formed on the inner surface of the housing (11), i.e., a first power transmission surface (31), a second power transmission surface (32), and a ceiling surface (33). The first and second power transmission surfaces (31, 32) face the convex outer surface of the outer roller (23), and when torque is transmitted, one of the first and second power transmission surfaces (31, 32) contacts the outer surface of the outer roller (23) depending on the rotational direction, so that power is transmitted. The first and second power transmission surfaces (31, 32) may have a concave curved shape corresponding to the convex outer surface of the outer roller (23). For example, when power is transmitted to the spider (12) while the housing (11) rotates clockwise in FIG. 2, the first power transmission surface (31) contacts the outer surface of the outer roller (23) to transmit power. Conversely, when power is transmitted to the spider (12) while the housing (11) rotates counterclockwise in FIG. 2, the second power transmission surface (32) contacts the outer surface of the outer roller (23) to transmit power. When power is transmitted while the spider (12) is angled relative to the housing (11), the outer roller (23) performs a rolling motion on the first power transmission surface (31, 32). In this respect, among the first and second power transmission surfaces (31, 32), the surface that performs the power transmission function can be referred to as a rolling contact surface.

[0042] A structure is applied in which the tilting of the outer roller (23) is limited. First, referring to FIG. 4, when the outer roller (23) is tilted in the indicated tilt direction (T1) while the first power transmission surface (31) and the outer peripheral surface of the outer roller (23) form a rolling contact surface, the central axis (X1) of the outer roller (23) tilts from the reference state (X0) and the outer end of the outer roller (23) contacts the ceiling surface (33), thereby limiting the tilting of the outer roller (23). That is, when the outer roller (23) is tilted so that the portion corresponding to the opposite side of the rolling contact surface moves radially outward, the outer end of the joint radially of the outer roller (23) contacts the ceiling surface (33), thereby limiting the tilting of the outer roller (23).

[0043] Referring to FIG. 5, when the outer roller (23) is tilted in the indicated tilt direction (T2) while the first power transmission surface (31) and the outer surface of the outer roller (23) form a cloud contact surface, the central axis (X2) of the outer roller (23) tilts from the reference state (X0), and the tilting limiting surface (52) provided at the inner end of the outer roller (23) comes into contact with the tilting limiting surface (51) provided at the housing (11). The tilting limiting surface (52) of the outer roller (23) may be provided at the inner end of the outer surface of the outer roller (23), and the tilting limiting surface (51) of the housing (11) may be arranged adjacent to the power transmission surfaces (31, 32).

[0044] The tilting limiting surface (52) of the outer roller (23) and the tilting limiting surface (51) provided on the inner surface of the housing (11) are brought into contact with each other, thereby limiting the additional tilting of the outer roller (23). That is, when the outer roller (23) is tilted so that the portion corresponding to the opposite side of the rolling contact surface moves radially inward, the tilting limiting surface (52) provided on the inner end of the joint radially of the outer roller (23) on the side forming the rolling contact surface comes into contact with the tilting limiting surface (51) provided on the inner surface of the housing (11), thereby limiting the tilting of the outer roller (23). As a result, the tilting of the outer roller (23) is limited, thereby enabling smooth rolling movement.

[0045] The tilting limiting surface (51) provided in the housing (11) may have a flat shape, and the tilting limiting surface (52) provided in the outer roller (23) may have a convex shape.

[0046] FIG. 6A is a drawing showing the shape of a tilting restriction surface of a tripod constant velocity joint according to another embodiment of the present invention. FIG. 6B is a drawing showing the shape of a tilting restriction surface of a tripod constant velocity joint according to still another embodiment of the present invention. First, referring to FIG. 6A, the tilting restriction surface (53) provided on the housing (11) has a convex shape, and the tilting restriction surface (54) provided on the outer roller (23) has a flat shape. Next, referring to FIG. 6B, both the tilting restriction surface (55) provided on the housing (11) and the tilting restriction surface (56) provided on the outer roller (23) have a flat shape. At this time, when the outer roller (23) tilts, the corner of the outer peripheral surface of the outer roller (23) may be configured to contact the tilting restriction surface (55) of the housing (11).

[0047] FIG. 7 is a drawing showing a state in which an outer roller is in close contact with a power transmission surface of a housing and is not tilted in a tripod constant velocity joint according to an embodiment of the present invention. FIG. 7 shows a state in which the outer roller (23) is in close contact with a first power transmission surface (31) of a housing (11) in a non-tilted state, and at this time, the outer surface of the outer roller (23), the upper surface in FIG. 7, is parallel to the ceiling surface (33) of the housing (11). In this state, as shown in the dotted circle, a gap (G) exists between the tilting restriction surface (51) of the housing (11) and the tilting restriction surface (52) of the outer roller (23), and this gap (G) may fall within a range of 0.005 to 0.055 mm. This gap allows for a slight tilting of the outer roller (23) as described above.

[0048] Also, referring to FIG. 7, the ratio of the tilting limit surface (52) of the outer roller (23) to the radius of curvature (R1) of the outer surface of the outer roller (23) may fall within the range of 0.4 to 0.6.

[0049] FIG. 8 is a drawing showing the side surface of the guide groove and the shape of the outer roller of the tripod constant velocity joint according to another embodiment of the present invention. Referring to FIG. 8, the tilting limitation structure (61, 62), that is, the structure of two tilting limitation surfaces that can contact each other as described above, may be provided on each side of the center line (CL) of the power transmission surface (31, 32) of the housing (11). Here, the center line (CL) may be defined as a line connecting the peak points of the first and second power transmission surfaces (31, 32).

[0050] Fig. 9 is a front view of a tripod constant velocity joint according to an embodiment of the present invention. According to an embodiment of the present invention, the outer diameter (D) of the outer roller (23) O ) and the pitch circle diameter (PCD) of the housing (11) (PCD H) can be in the range of 0.8 to 0.95. Here, the pitch circle diameter of the housing (11) can be defined as the diameter of a circle inscribed in the center line (CL) of the power transmission surfaces (31, 32) of the three guide grooves (15).

[0051] Figure 10 is a graph comparatively showing the force generated due to internal friction of a tripod constant velocity joint according to an embodiment of the present invention and a conventional tripod constant velocity joint. The tripod constant velocity joint according to an embodiment of the present invention significantly reduces the force generated due to internal friction by limiting the tilting of the outer roller, which leads to improved efficiency.

[0052] 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 guide grooves arranged along the circumference; A spider including a hub disposed within the housing and three journals each protruding radially outward from the hub and each disposed in the guide groove; and It comprises three roller assemblies each fastened to the journal and acting as a medium for transmitting rotational power between the journal and the housing, The above guide groove includes a ceiling surface and first and second power transmission surfaces provided on both sides of the ceiling surface, The roller assembly includes an inner roller arranged to surround the journal and an outer roller arranged on the outside of the inner roller, The first and second power transmission surfaces are configured so that power can be transmitted by interaction with the outer surface of the outer roller, The above outer roller includes a first tilting limiting surface provided on the inner end of the outer surface, A tripod constant velocity joint, wherein the housing includes a second tilting limiting surface that contacts the first tilting limiting surface when the outer roller is tilted to limit further tilting of the outer roller.

2. In paragraph 1, A tripod constant velocity joint in which the outer roller is configured to contact the ceiling surface on the other side of the outer surface when tilted while one side of the outer surface is in contact with the first power transmission surface.

3. In paragraph 1, The above first tilting limit surface has a convex curved shape, The above second tilting limit surface is a tripod constant velocity joint having a flat shape.

4. In paragraph 1, The above first tilting limit surface has a flat shape, The above second tilting limit surface is a tripod constant velocity joint having a convex curved shape.

5. In paragraph 1, A tripod constant velocity joint in which the first tilting restriction surface and the second tilting restriction surface each have a flat shape.

6. In paragraph 1, A tripod constant velocity joint in which a preset gap exists between the first tilting restriction surface and the second tilting restriction surface while the outer roller is not tilted and is in close contact with the first power transmission surface.

7. In paragraph 6, The above preset gap is a tripod constant velocity joint in the range of 0.005 mm to 0.1 mm.

8. In paragraph 1, The above first tilting limiting surface is provided on each side of the center line of the first and second power transmission surfaces, The above second tilting limiting surface is a tripod constant velocity joint provided on each side of the center line of the first and second power transmission surfaces.

9. In paragraph 1, A tripod constant velocity joint in which the ratio of the outer diameter of the outer roller to the pitch circle diameter of the housing is in the range of 0.8 to 0.

95.

10. In paragraph 1, A tripod constant velocity joint in which the ratio of the radius of curvature of the first tilting restriction surface to the radius of curvature of the outer surface of the outer roller is in the range of 0.4 to 0.6.

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