Sealing structure of a coupling
By designing a convex, curved sealing lip in the coupling sealing structure, the problem of grease leakage caused by centrifugal force is solved, the sealing performance is improved, and the sealing effect of the grease is ensured.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-15
- Publication Date
- 2026-07-14
AI Technical Summary
In the prior art, lip seals may leak grease and air together under centrifugal force, resulting in insufficient sealing.
A coupling sealing structure was designed, wherein the lip of the sealing member is convex in the radial direction and bends on the outer ring surface. The rate of increase of the rotation radius of the bending surface on the end side is smaller than that on the base side, thereby reducing the centrifugal force pushing out the grease.
By reducing the centrifugal force pushing out the grease, the sealing performance is improved, preventing the grease from leaking out of the sealing components and enhancing the sealing effect.
Smart Images
Figure CN224497156U_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a sealing structure for couplings used, for example, on the drive shaft of a vehicle. Background Technology
[0002] Patent Document 1 describes an example of such a sealing structure. To briefly describe this structure, the star-shaped shaft, which serves as the universal joint's cross shaft, has shaft portions protruding in four directions: up, down, left, and right. Bearings are mounted on these shaft portions, with an outer ring serving as the outer ring. A lip seal is provided to seal the outer ring and shaft portions in a liquid-tight state. Inside this lip seal, the pressure increases due to factors such as rising temperature. In this situation, there is a possibility that the grease or other substances sealed inside may leak out. To avoid or suppress this, an air venting path is provided between the lip seal and the star-shaped shaft, allowing the pressure inside the outer ring to escape to the outside when it rises. Therefore, the lip seal described in Patent Document 1 can suppress deformation of the seal caused by the grease lip of the lip seal flipping up or opening due to pressure changes inside the outer ring.
[0003] Existing technical documents
[0004] Patent documents
[0005] Patent Document 1: Japanese Patent Application Publication No. 2009-257406 Utility Model Content
[0006] The problem to be solved by the utility model
[0007] The lip seal described in Patent Document 1 allows pressure inside the outer ring to escape, preventing deformation of the lip or opening of the seal. However, in this structure, because the internal pressure increases, it forms an open lip shape. Therefore, when centrifugal force acts on the lip, or when centrifugal force acts on the lubricating material inside the lip, causing the lubricating material to push the lip open, air inside will escape to the outside, just like when the internal pressure increases. Therefore, when centrifugal force is applied frequently or for a long time, there is a possibility that the internal lubricating material will leak to the outside along with the air.
[0008] This utility model was developed in response to the aforementioned technical issues. Its purpose is to provide a sealing structure for couplings that reduces the leakage of lubricating grease due to centrifugal force and improves sealing performance.
[0009] Methods for solving problems
[0010] To achieve the above objectives, this utility model provides a sealing structure for a coupling. The coupling has four support shafts protruding radially relative to the axis of rotation, arranged at equal intervals circumferentially in a star-shaped shaft configuration. A fork-shaped connector can be rotatably fitted onto the support shafts via a bearing lubricated by a lubricating material, connecting the rotating shafts to the fork-shaped connector. Thus, a pair of rotating shafts can be rotatably connected via the star-shaped shafts. The bearing is characterized by having an outer ring that holds the rotating body and is equipped with a sealing member. The sealing member, when fitted onto the support shaft, contacts the outer surface of the outer ring to achieve a liquid-sealed seal between the support shaft and the outer ring. The sealing member is equipped with a lip, which extends from the surface of the bearing when fitted onto the support shaft. The base of the support shaft extends toward the outer ring and contacts the outer surface of the outer ring. The lip is convex outward in the radial direction relative to the central axis of the support shaft, and the end portion is curved from the outside to the inside in the radial direction of the outer ring and contacts the outer surface of the outer ring. Furthermore, the inner surface of the lip becomes a curved surface with the radius of rotation gradually increasing from the rotation center axis of the star-shaped shaft to the end portion side that contacts the outer surface of the outer ring. The curved surface has a bend on the side closer to the base than the end portion. The rate of increase of the radius of rotation in the curved surface on the end portion side, which contains the bend, is smaller than the rate of increase of the radius of rotation in the curved surface on the base side, which contains the bend.
[0011] Effects of the utility model
[0012] The sealing structure of this coupling has a smaller rate of increase in the radius of rotation of the curved surface containing the bend at the end than that containing the bend at the base. That is, the angle of the curved surface near the end relative to the outer surface of the outer ring is larger than the angle relative to the direction in which the lubricating material flows out. Therefore, the component force exerted by centrifugal force in the direction towards the end (towards the bottom of the outer ring) is reduced. In other words, the force causing the grease to escape outward due to centrifugal force is weakened, reducing the leakage of grease from the sealing member and improving sealing performance. Attached Figure Description
[0013] Figure 1 This is a diagram used to illustrate the structure of a universal joint.
[0014] Figure 2 This is a diagram used to illustrate the structure of the star shaft of a universal joint, and it is a cross-sectional view cut by a plane perpendicular to the axis of rotation.
[0015] Figure 3 This is a diagram illustrating the sealing structure of the coupling of this utility model. Figure 2The enlarged cross-sectional view of part A in the figure.
[0016] Explanation of reference numerals in the attached drawings: 1 Universal coupling, 2 Joint, 3 Star shaft, 4 Support shaft, 5 Bearing, 6 Roller, 7 Cover, 8 Sealing component, 8a Base, 8b Grease lip, 8c Dustproof lip, 8d End portion, 8e Bend surface, 8f Bend portion, 9 Boss portion, 10 Grease, 11 Space, F Centrifugal force, S Rotating shaft Detailed Implementation
[0017] The embodiments of this utility model are described below with reference to the accompanying drawings. Furthermore, the embodiments described below are merely one example of implementing this utility model and do not limit the scope of this utility model.
[0018] This utility model is a sealing structure for a coupling used to connect rotating shafts. As an example of a coupling, in... Figure 1 The figure shows a universal joint that uses a star-shaped shaft. Figure 1 The universal joint shown (hereinafter, sometimes simply referred to as the joint) 1 is a previously known structure, constructed by connecting a pair of double-convex joints (or fork joints) 2 using a common star shaft 3. Rotating shafts are connected to each joint 2, and each joint 2 is rotatable relative to the star shaft 3. Thus, each rotating shaft S is connected in a bent state at the location of the star shaft 3, and torque can be transmitted between them in this bent state.
[0019] As is well known, the star-shaped shaft 3 is a component that appears cross-shaped when viewed from the front, having support shafts 4 that protrude in four mutually orthogonal directions—up, down, left, and right—relative to the center in the circumferential direction. Figure 2 A portion of it is shown in a cross-sectional diagram. For the star-shaped shaft, one joint 2 is rotatably fitted to a pair of upper and lower support shafts 4, and another joint 2 is rotatably fitted to a pair of left and right support shafts 4. Thus, one joint 2 can rotate around the upper and lower pair of support shafts 4, and the other joint 2 can rotate around the left and right pair of support shafts 4, so that they can be rotatably connected while the rotating shaft S is bent relative to each other at a predetermined angle.
[0020] The connection structure between each support shaft 4 and joint 2 is described below. Figure 2 The mating parts are shown in cross-sectional views. Additionally, the mating parts of the support shaft 4 and the joint 2 exist at four locations, the same number as the number of support shafts 4. However, since they are all identical structures, the same reference numerals are used for parts or components with the same name.
[0021] A bearing 5 is positioned between the support shaft 4 and the joint 2 in a manner that allows them to rotate relative to each other. The bearing 5 can also be any bearing known in the past, such as a sliding bearing or a rotary bearing. Figure 2 In the example shown, a roller bearing is used as bearing 5. That is, bearing 5 is a rotary bearing in which multiple rollers (or rotating pins) 6 arranged along the outer circumferential surface of the support shaft 4 serve as rotating bodies. These rollers 6 are arranged along the inner circumferential surface of the cover 7 with their rotational axis parallel to the central axis of the support shaft 4. The rollers 6 are held in close contact with the outer circumferential surface of the support shaft 4 by the cover 7. Thus, the outer circumferential surface of the support shaft 4 forms the inner housing of bearing 5, and the inner circumferential surface of the cover 7 forms the outer ring of bearing 5.
[0022] like Figure 2 As shown, the cover 7 is a cylindrical metal component with a bottom that covers the entire end portion of the support shaft 4. Thus, the end side of the support shaft 4 or bearing 5 (the outer side in the radial direction of the star shaft 3) is covered by the bottom of the cover 7, shielding it from the outside and preventing the intrusion of dust or moisture, or leakage of lubricating material. Conversely, at the root portion of the support shaft 4, in other words, at the open end of the cover 7, a sealing member 8 made of an elastic material such as rubber is provided.
[0023] The sealing member 8 is provided to prevent dust or mud from entering the bearing 5 from the root side of the support shaft 4, and also to prevent leakage of lubricating materials such as grease. Figure 2 As shown, the sealing member 8 is integrally formed in a ring shape. In contrast, at the root portion of the support shaft 4, a large-diameter boss 9 is formed, which is slightly larger than the outer diameter of the support shaft 4 (the outer diameter of the portion in contact with the roller 6). The sealing member 8 is fitted into this boss 9 in a liquid-tight state.
[0024] exist Figure 3 The cross-sectional shape of the sealing member 8 is shown in magnified view. Here, as... Figure 2 or Figure 3 As shown, the cross section is a cross section cut in a plane perpendicular to the rotation center axis of the star-shaped axis 3, or a cross section cut in a plane containing the central axis of the sealing member 8 (or the central axis of the support shaft 4 or the cover 7 assembled thereon).
[0025] The sealing member 8 has a thick base 8a that fits into the aforementioned boss 9, and two lips 8b and 8c extending from the base 8a toward the opening end of the cover 7. One lip 8b is a thin annular piece extending from the inner circumferential side of the base 8a in the axial direction (towards the opening end of the cover 7), and will be referred to below as the grease lip 8b. The other lip 8c is a thin annular piece extending from the outer circumferential side of the base 8a in the axial direction (towards the opening end of the cover 7), and will be referred to below as the dustproof lip 8c.
[0026] Compared to the dustproof lip 8c, the grease lip 8b has a smaller diameter and a shorter axial length. The grease lip 8b contacts the side of the end side of the cover 7 (the root side of the support shaft 4), with its tip pointing outwards in the radial direction of the support shaft 4. In contrast, the dustproof lip 8c is an annular piece with a diameter approximately the same as the outer diameter of the cover 7, and its axial length is longer than that of the grease lip 8b. Furthermore, the end portion 8d of the dustproof lip 8c approximately reaches the outer circumferential surface of the cover 7 and contacts its outer surface. Thus, the inner circumference of the cover 7 is shielded from the outside by these lips 8b and 8c, preventing dust or stopping or suppressing leakage of lubricating material.
[0027] The shape of the dustproof lip 8c will now be described in more detail. The dustproof lip 8c has a shape that curves from the outside to the inside in the radial direction of the cover 7 and contacts the outer peripheral surface of the end side of the cover 7 or the outer surface of the corner from the outer peripheral surface to the side surface. Furthermore, as... Figure 3 As shown in the enlarged view, the inner surface of the dustproof lip 8c has a cross-sectional shape that is convex and arc-shaped, and has a curved surface 8e with a radius of rotation that gradually increases from the rotation center axis of the star-shaped shaft 3 to the end portion 8d that contacts the outer surface of the cover 7.
[0028] The curved surface 8e has a bend 8f on the side closer to the base 8a than the end portion 8d. The rate of increase of the radius of rotation of the curved surface 8e sandwiched by the bend 8f on the end portion 8d side is smaller than the rate of increase of the radius of rotation of the curved surface 8e sandwiched by the bend 8f on the base 8a side. Here, the rate of increase of the radius of rotation is the increase per unit amount of the distance (radius of rotation) between the curved surface 8e and the center of rotation of the star-shaped axis 3 relative to the central angle at that center of rotation.
[0029] The grease 10 used as the lubricating material for the bearing 5 is stored in a space 11 surrounded by the end side of the cover 7 (the root side of the support shaft 4) or the inner circumferential side of the cover 7 and the radially inner side of the support shaft 4 of the grease lip 8b.
[0030] Next, the function and effect of the sealing structure of the coupling of this utility model will be explained. When the star shaft 3 rotates, as... Figure 2 , 3 As shown, a centrifugal force F is generated in the radial direction of the rotation center axis. The centrifugal force F also acts on the grease 10 inside the sealing member 8. Inside the dust lip 8c, the grease 10 is pressed against the curved surface 8e, which serves as the inner circumferential surface. As described earlier, this curved surface 8e is formed as a surface with a gradually increasing radius of rotation (radius from the rotation center of the star-shaped shaft 3) at the end side of the dust lip 8c. Therefore, the grease 10 pressed against the curved surface 8e is pushed along this curved surface 8e towards the end side of the grease lip 8c. If... Figure 3As illustrated in the cross-sectional view, the smaller the angle between the direction of the centrifugal force F and the tangent to the curved surface 8e, the greater the force that pushes the grease 10 along the direction of the curved surface 8e. In other words, when the centrifugal force F is decomposed into a component Fa in the normal direction at a specified point on the curved surface 8e and a component Fb in the direction (tangential direction) along the curved surface 8e, the component Fb in the tangential direction becomes the force that pushes the grease 10 along the direction of the curved surface 8e.
[0031] As described above, a bend 8f is provided on the curved surface 8e. The rate of increase of the radius of rotation of the curved surface 8e sandwiched by the bend 8f on the end portion 8d side is smaller than the rate of increase of the radius of rotation of the curved surface 8e sandwiched by the bend 8f on the base portion 8a side. Therefore, the angle between the direction of the centrifugal force F and the tangent to the curved surface 8e decreases on the base portion 8a side and increases on the end portion 8d side, with the bend 8f as the boundary. If this is explained using the component force Fb along the curved surface 8e, this component force Fb increases on the base portion 8a side and decreases on the end portion 8d side, with the bend 8f as the boundary. Since the force that pushes the grease 10 along the curved surface 8e or such action is the force or action that pushes the grease 10 out of the sealing member 8, in the above embodiment, this force (component force Fb) becomes smaller at the end portion 8d side of the dust lip 8c, thereby reducing the leakage of grease 10 from the sealing member 8 and improving the sealing performance.
Claims
1. A sealing structure for a coupling, the coupling having a star-shaped shaft formed by four support shafts projecting radially relative to a rotation center axis and equally spaced in the circumferential direction, such that a fork-shaped joint can be rotatably fitted onto the support shafts via bearings lubricated by a lubricating material, connecting a rotating shaft to the fork-shaped joint, thereby rotatably connecting a pair of rotating shafts via the star-shaped shafts, characterized in that... The bearing has an outer ring that holds the rotating body. A sealing member is provided, which, when fitted onto the support shaft, contacts the outer surface of the outer ring to seal the space between the support shaft and the outer ring in a liquid-tight manner. The sealing member is equipped with a lip that extends from the base fitted into the support shaft toward the outer ring and contacts the outer surface of the outer ring. The lip is convex outward in the radial direction relative to the central axis of the support shaft, and the end portion is curved inward in the radial direction of the outer ring and contacts the outer surface of the outer ring. Furthermore, the inner surface of the lip becomes a curved surface with a radius of rotation that gradually increases from the rotation center axis of the star-shaped axis to the end portion that contacts the outer surface of the outer ring. The curved surface has a bend on the side closer to the base than the end portion. The rate of increase of the radius of rotation in the curved surface sandwiched between the bends on the end side is smaller than the rate of increase of the radius of rotation in the curved surface sandwiched between the bends on the base side.