Grease seal structure for vehicle constant velocity joint and constant velocity joint including the same

Abstract

The grease seal structure can provide a grease seal that seals the grease filled between the outer ring and the inner ring of the constant velocity joint and includes a shroud that can be supported in close contact with each of the outer ring and the inner ring, a clamp cap fastened to the outer ring to restrict movement of the outer ring in an axial direction and capable of pressing the shroud in the axial direction of the outer ring and thereby bringing the shroud in close contact with the outer ring, and a seal ring capable of being fastened to the shroud to press the shroud against the outer peripheral surface of the inner ring.

Description

Technical Field

[0001] The present invention relates to a constant velocity joint for transmitting driving force of a vehicle, and more specifically to a grease sealing structure for sealing the grease of the constant velocity joint. Background Technology

[0002] A constant velocity joint is a device that transmits rotational driving force and is used to transmit rotational driving force by connecting with the drive shaft, transmission shaft, etc. of a vehicle.

[0003] Constant velocity joints, such as Rzeppa universal joints, consist of an outer ring, an inner ring, multiple balls disposed between the outer and inner rings, and a ball cage housing these balls. In such constant velocity joints, the outer ring typically has an open side through which the balls, ball cage, and inner ring are inserted. The space between the outer and inner rings containing the balls and ball cage is filled with grease for lubrication. To seal the grease, a shroud is typically attached to both the outer and inner rings. Generally, the shroud is secured to both the outer and inner rings using a press-fit method with clamps. Typically, a clamp is used to press and secure one side of the shroud to the radially outer surface of the outer ring, and another clamp performs the same operation on the radially outer surface of the inner ring. The shroud is subjected to continuous shape deformation and load, thus requiring excellent durability to maintain the grease seal. Because the shroud is fixed to the radially outer surface of the outer ring, the radius of rotation increases, creating a serious problem of potential radial expansion of the shroud.

[0004] In particular, when constant velocity joints are applied to drive shafts, which rotate at very high speeds such as 6000 RPM and 8000 RPM, it is difficult to maintain a grease seal using conventionally widely used crimping methods with clamps. Drive shafts not only rotate at approximately three times the speed of drive shafts typically used in front or rear wheels, but they also have a large radius of rotation, resulting in significant potential for radial expansion. Therefore, when conventional sealing structures are applied to constant velocity joints used in drive shafts, problems arise with guard damage and grease leakage.

[0005] <Existing Literature>

[0006] - U.S. Patent No. US8,313,107 (November 20, 2012)

[0007] - U.S. Patent No. US9,494,199 (November 15, 2016) Summary of the Invention

[0008] Technical Purpose

[0009] The purpose of this invention is to provide a grease sealing structure for constant velocity joints that can effectively prevent damage to the protective cover and grease leakage, even when applied to constant velocity joints with high-speed rotation and a large rotation radius.

[0010] Technical solution

[0011] According to an embodiment of the present invention, a grease sealing structure provides a seal for grease filled between an outer ring and an inner ring of a constant velocity universal joint and includes: a shroud formed to be tightly fitted and supported on both the outer ring and the inner ring; a clamping cap configured to be fastened to the outer ring to restrict movement of the outer ring in the axial direction and to compress the shroud in the axial direction of the outer ring to ensure a tight fit between the shroud and the outer ring; and a sealing ring configured to be fastened to the shroud to press the shroud against the outer peripheral surface of the inner ring.

[0012] The cover may include a first fixing part configured to be fastened to an outer ring, a second fixing part configured to be fastened to an inner ring, and a connecting part connecting the first fixing part and the second fixing part. The first fixing part may be supported on the outer ring in the axial direction by a clamping cap, and the second fixing part may be configured to be supported on the inner ring in the radial direction by a sealing ring.

[0013] The clamping cap may include: a fastening portion that is fastened to the outer ring to restrict movement in the axial direction; and a support portion that extends radially from one end of the fastening portion to compress the first fixing portion in the axial direction.

[0014] The clamping cap may also include a motion limiting portion that bends radially inward from one end of the fastening portion to limit movement in the axial direction.

[0015] The clamping cap may also include an expansion limiting portion that extends axially from the inner end of the support portion and is formed to be positioned radially outside the connection portion of the cover.

[0016] The connecting portion of the shield may include an axial extension extending from the radially inner end of the first fixing portion in the axial direction and a corrugated portion with a corrugated shape connecting the axial extension and the second fixing portion, and the expansion limiting portion may be configured to surround the outer side of the axial extension.

[0017] The expansion limiting portion can be configured to be spaced apart from the outer surface of the axial extension when the outer and inner rings are in a state where they are not angularly displaced from each other.

[0018] The expansion limiting portion can be configured such that the distance between it and the outer surface of the axial extension remains constant along the axial direction.

[0019] The expansion limiting portion can be configured such that the distance separating it from the outer surface of the axial extension gradually increases or decreases along the axial direction.

[0020] A constant velocity universal joint according to an embodiment of the present invention includes: an outer ring having a plurality of outer ball grooves; an inner ring having a plurality of inner ball grooves respectively mating with the outer ball grooves; a plurality of balls respectively positioned in the spaces formed by the mating outer ball grooves and inner ball grooves; a ball carrier receiving the plurality of balls; and a grease sealing structure providing grease to fill the space between the outer ring and the inner ring containing the balls and the ball carrier. The grease sealing structure includes: a shield formed to be tightly fitted and supported on both the outer ring and the inner ring; a clamping cap configured to be fastened to the outer ring to restrict movement of the outer ring in the axial direction and to compress the shield in the axial direction of the outer ring to ensure a tight fit between the shield and the outer ring; and a sealing ring configured to be fastened to the shield to press the shield against the outer peripheral surface of the inner ring.

[0021] A groove can be formed on the support surface of the first fixing part of the outer ring, and the first fixing part can be provided with a sealing protrusion inserted into the groove.

[0022] A groove can be formed on the support surface of the second fixing part of the inner ring at a position corresponding to the sealing ring.

[0023] Invention Effects

[0024] According to the present invention, since the cover is fixed by applying pressure to the outer ring in the axial direction of the outer ring by the clamping cap attached to the outer ring, the rotation radius of the cover can be minimized and excessive expansion of the cover can be prevented. Attached Figure Description

[0025] Figure 1 This is a front view of a constant velocity universal joint with a grease-sealed structure according to an embodiment of the present invention.

[0026] Figure 2 This is an exploded perspective view of a constant velocity universal joint with a grease-sealed structure according to an embodiment of the present invention.

[0027] Figure 3 It is along Figure 1 The sectional view taken from line III-III.

[0028] Figure 4 yes Figure 3 A magnified view of a portion of the image. Detailed Implementation

[0029] In the following detailed description of embodiments of the present invention, with reference to the accompanying drawings.

[0030] Reference Figures 1 to 3The constant velocity universal joint 10 includes an outer ring 11 and an inner ring 13 configured to connect to separate power transmission elements. Balls 15 serve as the medium for transmitting torque and are positioned between the outer ring 11 and the inner ring 13, housed within cavities 171 of a ball carrier 17. Multiple balls 15 can be provided, and the outer ring 11 and the inner ring 13 may each have paired outer ball grooves 114 and inner ball grooves 133 forming spaces to accommodate each ball 15. Rotational power transmission between the outer ring 11 and the inner ring 13 is achieved through the balls 15 positioned within the spaces formed by the outer ball grooves 114 and the inner ball grooves 133. Figure 2 An example is shown with eight balls 15, but the number of balls 15 is not limited to this and can vary, for example, six, ten, etc.

[0031] The outer ring 11 may include a power transmission portion 111 with an outer ball groove 114 formed on its inner surface, a connecting portion 113 configured to connect to a power transmission shaft (not shown), and a connecting portion 112 connecting the power transmission portion 111 and the connecting portion 113. The outer ring 11 may form a through hole 118 extending along the axial direction X1 and penetrating the power transmission portion 111, the connecting portion 112, and the connecting portion 113. The inner ring 13 may include a power transmission portion 131 with an inner ball groove 133 formed on its outer surface and a shaft portion 132 extending from the power transmission portion 131 in the axial direction X2. The inner ring 13 may form a through hole 138 extending along the axial direction X2 and penetrating the power transmission portion 131 and the shaft portion 132. For example, when the constant velocity universal joint according to an embodiment of the present invention is installed between the differential gear and the drive shaft, the inner ring 13 can be coupled to the output shaft of the differential gear inserted in the through hole 138 via spline coupling, and the connecting portion 113 of the outer ring 11 can be coupled to the hollow shaft of the drive shaft via welding.

[0032] The outer ring 11 and the inner ring 13 can be configured to rotate while being angularly displaced from each other to transmit power. Figure 3 In this design, the longitudinal axes X1 and X2 of the outer ring 11 and the inner ring 13 are represented as being coaxial without angular displacement. In the angular displacement state, the relative positions of the outer ring 11 and the inner ring 13 change, causing the two longitudinal axes X1 and X2 to no longer align parallel to each other. The constant velocity universal joint according to an embodiment of the invention is designed to allow the outer ring 11 and the inner ring 13 to rotate while simultaneously displacing angularly within a predetermined angular range.

[0033] Although not shown in the figure, grease fills the space between the balls 15 and the ball carrier 17 for lubrication. (See reference...) Figure 2 and Figure 3In order to prevent grease from leaking through the through hole 118 of the outer ring 11 and the through hole 138 of the inner ring 13, the grease retainers 25 and 27 that can block these through holes 118 and 138 can be coupled to the outer ring 11 and the inner ring 13, respectively.

[0034] A grease seal structure 20 provides a grease seal between the outer ring 11 and the inner ring 13. The grease seal structure 20 may include a shroud 19, a clamping cap 21, and a sealing ring 23. The shroud 19 fits tightly with both the outer ring 11 and the inner ring 13 to prevent grease filling the space between the balls 15 and the ball carrier 17 from leaking through the space between the outer ring 11 and the inner ring 13. The shroud 19 can be compressed by the clamping cap 21 to fit tightly with the outer ring 11 and can be compressed by the sealing ring 23 to fit tightly with the inner ring 13.

[0035] The cover 19 may include a first fixing portion 191 for fastening to the outer ring 11, a second fixing portion 194 for fastening to the inner ring 13, and connecting portions 192 and 193 connecting the first fixing portion 191 and the second fixing portion 194. The cover 19 may be made of a material capable of elastic deformation, such as rubber. The connecting portions 192 and 193 may be configured to allow shape deformation during operation in a state of angular displacement. The first fixing portion 191 may be configured to fit tightly with an axial support surface 116 provided at the axial end X1 of the outer ring 11, and the second fixing portion 194 may be configured to fit tightly with a radial support surface 134 provided on the radially outer surface of the inner ring 13.

[0036] In one embodiment of the present invention, such as Figure 3 and Figure 4 As shown, the first fixing part 191 can extend substantially perpendicular to the axial direction X1 of the outer ring 11, and the second fixing part 194 can extend substantially parallel to the axial direction X2 of the inner ring 13. In embodiments of the present invention, as Figure 3 and Figure 4 As shown, the connecting portion may include two parts: an axially extending portion 192 extending substantially parallel to the axial direction X2 of the inner ring 13 from the inner end of the first fixing portion 191, and a corrugated portion 193 having a corrugated shape for connecting one end of the axially extending portion 192 to the second fixing portion 194. The corrugated portion 193 may have a corrugated shape extending in a sawtooth shape relative to the radial direction, thereby allowing for [various connections] in both the axial direction X2 and the radial direction ([missing information]). Figure 4 It can easily shift in the vertical direction.

[0037] The clamping cap 21 is configured to be fixed to the outer ring 11 and to pressurize the first fixing portion 191, which is to be securely fixed to the axial support surface 116, in the axial direction X1. For more details, see... Figure 4The clamping cap 21 includes a fastening portion (i.e., an axial extension 211) attached to the power transmission portion 111 of the outer ring 11, and a support portion 212 extending radially inward from one end of the axial extension 211 to press and clamp the first fixing portion 191 in the axial direction X1. The axial extension 211 has a hollow cylindrical shape and can be press-fitted with the power transmission portion 111. In this respect, the motion limiting portion 214 is deformed by a chamfering to be engaged by the claws 219 of the outer ring 11, thereby providing a fastening force in the axial direction X1. For example, the motion limiting portion 214 can be... Figure 4 The dashed circle shows the parallel axial extension 211 extending to the outer ring 11, which is press-fitted with the outer ring 11, and after press-fitting, it can be crimped to achieve the desired fit. Figure 4 The shape is deformed as shown to be fastened to the claw 219 of the outer ring 11. In this respect, to make the deformation of the motion limiting part 214 easier, a slope 215 can be provided on the outer surface of the motion limiting part 214.

[0038] like Figure 3 and Figure 4 As shown, while the clamping cap 21 is constrained in the axial direction X2 by the axial extension 211 and the motion limiting part 214 and fixed to the outer ring 11, the support part 212 presses against the first fixing part 191 in the axial direction X1. As a result, the first fixing part 191 of the cover 19 is tightly attached to the axial support surface 116 of the power transmission part 111 while being pressurized in the axial direction X1. Since the first fixing part 191 of the cover 19 is fixed to the axial support surface 116 of the outer ring 11 instead of the radial outer periphery of the outer ring 11, the rotation radius can be reduced.

[0039] Meanwhile, in order to enhance the sealing characteristics between the first fixing part 191 and the axial support surface 116, a groove 115 can be formed on the axial support surface 116, and the first fixing part 191 can be provided with a sealing protrusion 195 inserted in the groove 115. The groove 115 and the sealing protrusion 195 can have an annular shape extending along the circumferential direction of the power transmission part 111 of the outer ring 11.

[0040] The second fixing portion 194 of the cover 19 can be positioned radially inside the first fixing portion 191 and axially spaced apart. By pressing the radially outer surface of the second fixing portion 194 with the sealing ring 23, the second fixing portion 194 can be pressed tightly and attached to the radial support surface 134 of the inner ring 13. In this regard, in order to enhance the sealing characteristics between the second fixing portion 194 and the radial support surface 134, a groove 135 can be formed at a position corresponding to the position of the sealing ring 23, and a portion of the second fixing portion 194 can be configured to be inserted into the groove 135 due to its shape deformation when pressed.

[0041] Meanwhile, according to an embodiment of the present invention, an expansion limiting portion 213 is provided to limit the axial extension portion 192 in the radial direction ( Figure 4 The expansion in the vertical direction (within the structure) limits the radial expansion of the shield 19. For example... Figure 4 As shown, the expansion limiting portion 213 can extend from the radially inner end of the support portion 212, substantially parallel to the axial direction X1. The expansion limiting portion 213 can have a hollow cylindrical shape that extends in the axial direction X1 while being radially outwardly separated from the outer periphery of the axial extension portion 192. By limiting the radial expansion of the cover 19 by the expansion limiting portion 213, excessive expansion of the cover 19 can be prevented, and stress on the cover 19 can be minimized, thereby improving its durability. In addition, the expansion limiting portion 213 can also be used to protect the radially outer surface of the cover 19 from external contaminants or impacts. The distance between the expansion limiting portion 213 of the clamping cap 21 and the axial extension portion 192 of the cover 19 can be of an appropriate size, and the gap between them can be kept consistent along the axial direction or can be configured to increase or decrease.

[0042] Although embodiments of the present invention have been described above, the scope of the present invention is not limited thereto, but also includes all modifications and variations that are readily made by those skilled in the art and are considered equivalents thereto.

[0043] Industrial applicability

[0044] This invention relates to a constant velocity universal joint that can be used in vehicle drive mechanisms, and therefore has industrial applicability.

Claims

1. A grease sealing structure for sealing grease filled between the outer and inner rings of a constant velocity universal joint, comprising: The protective cover is formed to fit tightly against and be supported on both the outer ring and the inner ring; A clamping cap is configured to fasten to the outer ring to restrict movement of the outer ring in the axial direction and to press the cover in the axial direction of the outer ring to ensure a tight fit between the cover and the outer ring; as well as A sealing ring is configured to fasten to the shield to press the shield against the outer peripheral surface of the inner ring. The protective cover includes: The first fixing part is configured to be fastened to the outer ring and is supported on the outer ring in the axial direction by the clamping cap; The second fixing part is configured to be fastened to the inner ring and supported on the inner ring in the radial direction by the sealing ring; and The connecting part connects the first fixing part and the second fixing part. The clamping cap includes: A fastening part, which is fastened to the outer ring to restrict movement in the axial direction; A support portion, extending radially from one end of the fastening portion to press against the first fixing portion in the axial direction; and An expansion limiting portion extends axially from the inner end of the support portion and is positioned radially outward of the connecting portion of the cover. The connecting portion of the shield includes an axially extending portion extending radially inner from the first fixing portion in the axial direction, and a corrugated portion with a corrugated shape connecting the axially extending portion and the second fixing portion. The expansion limiting portion is configured to surround the outer side of the axial extension and to be spaced apart from the outer surface of the axial extension when the outer ring and the inner ring are not angularly displaced from each other.

2. The grease sealing structure according to claim 1, wherein, The clamping cap also includes a motion limiting portion that bends radially inward from one end of the fastening portion to limit movement in the axial direction.

3. The grease sealing structure according to claim 1, wherein, The expansion limiting portion is configured such that the distance between it and the outer surface of the axial extension remains constant along the axial direction.

4. The grease sealing structure according to claim 1, wherein, The expansion limiting portion is configured such that the distance separating it from the outer surface of the axial extension gradually increases or decreases along the axial direction.

5. A constant velocity universal joint, comprising: The outer ring forms multiple outer ball grooves; The inner ring has a plurality of inner ball grooves that are respectively paired with the outer ball grooves; Multiple balls are respectively positioned in the space formed by the paired outer ball groove and the inner ball groove; A ball cage that accommodates a plurality of the said balls; and A grease-sealing structure that provides grease to fill the space between the outer ring and the inner ring containing the balls and the ball cage. The grease sealing structure includes: The protective cover is formed to fit tightly against and be supported on both the outer ring and the inner ring; A clamping cap, configured to fasten to the outer ring to restrict movement of the outer ring in the axial direction and to compress the shield in the axial direction of the outer ring to ensure a tight fit between the shield and the outer ring; and A sealing ring is configured to fasten to the shield to press the shield against the outer peripheral surface of the inner ring. The protective cover includes: The first fixing part is configured to be fastened to the outer ring and is supported on the outer ring in the axial direction by the clamping cap; The second fixing part is configured to be fastened to the inner ring and supported on the inner ring in the radial direction by the sealing ring; and The connecting part connects the first fixing part and the second fixing part. The clamping cap includes: A fastening part, which is fastened to the outer ring to restrict movement in the axial direction; A support portion, extending radially from one end of the fastening portion to press against the first fixing portion in the axial direction; and An expansion limiting portion extends axially from the inner end of the support portion and is positioned radially outward of the connecting portion of the cover. The connecting portion of the shield includes an axially extending portion extending radially inner from the first fixing portion in the axial direction, and a corrugated portion with a corrugated shape connecting the axially extending portion and the second fixing portion. The expansion limiting portion is configured to surround the outer side of the axial extension and to be spaced apart from the outer surface of the axial extension when the outer ring and the inner ring are not angularly displaced from each other.

6. The constant velocity universal joint according to claim 5, wherein, The clamping cap also includes a motion limiting portion that bends radially inward from one end of the fastening portion to limit movement in the axial direction.

7. The constant velocity universal joint according to claim 5, wherein, The expansion limiting portion is configured such that the distance between it and the outer surface of the axial extension remains constant along the axial direction.

8. The constant velocity universal joint according to claim 5, wherein, The expansion limiting portion is configured such that the distance separating it from the outer surface of the axial extension gradually increases or decreases along the axial direction.

9. The constant velocity universal joint according to claim 5, wherein, A groove is formed on the support surface of the first fixing part on the outer ring, and the first fixing part is provided with a sealing protrusion inserted into the groove.

10. The constant velocity universal joint according to claim 5, wherein, A groove is formed on the support surface of the inner ring supporting the second fixing part at a position corresponding to the sealing ring.

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