Dust cover and ball joint

Abstract

This technology provides a way to reduce the risk of damage to a dust cover in which a reinforcing ring is embedded in the fixed portion. [Solution] The dust cover 12 is used in a ball joint. The dust cover comprises a fixed portion that is fixed to a socket, a sealing portion having an inner surface that contacts the outer surface of the shaft portion of the ball stud, and a body portion 53 located between the fixed portion 52 and the sealing portion and surrounding the shaft portion of the ball stud. A reinforcing ring is embedded in the fixed portion 52. The dust cover 12 further comprises an annular tilt-suppressing projection 56 that protrudes from the inner surface of the end of the body portion 53 on the fixed portion side, and which suppresses tilting of the body portion on the side on which the ball stud oscillates toward the inner surface when the ball stud oscillates.

Description

Technical Field

[0001] The present disclosure relates to a dust cover and a ball joint.

Background Art

[0002] A dust cover is used for a ball joint provided in various devices such as a vehicle to prevent intrusion of water, dust, etc. into the joint portion and to prevent outflow of grease from the joint portion. Conventionally, for example, a dust cover as described in Patent Document 1 has been proposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Generally, there are two types of structures for fixing a dust cover to a socket: one in which the part to be fixed is tightened from the outer circumference with a fastener, and another in which a reinforcing ring is embedded in the part to be fixed. In the former case, the dust cover can be forcibly removed from the mold after it has been molded, but in the latter case, because a reinforcing ring is embedded in the part to be fixed, the dust cover cannot be forcibly removed from the mold after it has been molded. Therefore, in the latter case, the inner diameter of the body of the dust cover must be less than or equal to the inner diameter of the part to be fixed. In this case, when the ball stud swings, the body of the dust cover on the side where the ball stud swings tends to tilt inward, and when the body tilts inward, it can come into contact with the ball stud. If the body of the dust cover repeatedly comes into contact with the ball stud due to the repeated swinging of the ball stud, the body may deteriorate and break. To prevent the body from tilting inward, it is conceivable to increase the height of the mating surface (outer surface) of the socket into which the fixed part is fitted; however, in that case, the swing angle will be limited.

[0005] This disclosure has been made in view of the aforementioned problems, and one exemplary objective of a certain aspect thereof is to provide a technology that can reduce the risk of damage to a dust cover in which a reinforcing ring is embedded in the fixed portion. [Means for solving the problem]

[0006] To solve the above problems, a dust cover in one aspect of the present disclosure is a dust cover used in a ball joint, the ball joint comprising a ball stud having a shaft portion and a spherical portion provided at one end of the shaft portion, and a socket having a bearing portion that supports the spherical portion and supports the ball stud so that it can rotate and swing freely. The dust cover comprises a fixed portion that is fixed to the socket, a sealing portion having an inner surface that contacts the outer surface of the shaft portion of the ball stud, and a body portion located between the fixed portion and the sealing portion and surrounding the shaft portion of the ball stud. A reinforcing ring is embedded in the fixed portion, and the dust cover further comprises an annular tilt-suppressing projection that protrudes from the inner surface of the end of the body portion on the fixed portion side, which suppresses tilting of the body portion on the side on which the ball stud swings toward the inner surface when the ball stud swings.

[0007] Another aspect of the present disclosure is a dust cover. This dust cover is used in a ball joint, the ball joint comprising a ball stud having a shaft portion and a spherical portion provided at one end of the shaft portion, and a socket having a bearing portion that supports the spherical portion and supports the ball stud rotatably and swingably. The dust cover comprises a fixed portion fixed to the socket, a sealing portion having an inner surface that contacts the outer surface of the shaft portion of the ball stud, and a body portion located between the fixed portion and the sealing portion and surrounding the shaft portion of the ball stud. A reinforcing ring is embedded in the fixed portion, and the dust cover comprises a tilt suppression portion that suppresses tilting of the body portion on the side of the ball stud that is swinging toward the inner circumference when the ball stud swings.

[0008] Another aspect of the present disclosure is a ball joint, which includes the dust cover described above. [Effects of the Invention]

[0009] According to one aspect of this disclosure, a technology can be provided that can reduce the risk of damage to a dust cover in which a reinforcing ring is embedded in the fixed portion. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view of a ball joint equipped with a dust cover according to an embodiment. [Figure 2] This is a cross-sectional view of the dust cover in Figure 1 when it is not attached. [Figure 3] Figure 3(a) is an enlarged cross-sectional view showing the protrusion that prevents the dust cover from collapsing and its surroundings when not installed, and Figure 3(b) is an enlarged cross-sectional view showing the protrusion that prevents the dust cover from collapsing and its surroundings when installed. [Figure 4] Figures 4(a) to 4(c) show the results of a simulation of how the dust cover of the comparative example deforms due to the oscillation of the ball stud. [Figure 5] Figures 5(a) to 5(c) show the results of a simulation of how the dust cover according to the embodiment deforms due to the oscillation of the ball stud. [Modes for carrying out the invention]

[0011] Preferred embodiments will be described below with reference to the drawings. These embodiments are illustrative and not limiting to the disclosure, and not all features or combinations thereof described in the embodiments are necessarily essential to the disclosure. The same or equivalent components, members, and processes shown in each drawing will be denoted by the same reference numerals, and redundant descriptions will be omitted where appropriate.

[0012] Figure 1 is a cross-sectional view of a ball joint 100 equipped with a dust cover 12 according to an embodiment. Figure 1 shows a cross-section including the central axis C1 of the socket 30 and the central axis C2 of the shaft portion 21 of the ball stud 20. Figure 1 shows the ball stud 20 in a state of oscillation relative to the socket 30. The oscillation angle θ is the acute angle formed by the central axis C1 and the central axis C2 in the cross-section including the central axes C1 and C2. Figure 2 is a cross-sectional view when the dust cover 12 is not attached. Figure 2 shows a cross-section including the central axis of the dust cover 12. Figure 3(a) is an enlarged cross-sectional view showing the tilt-suppression projection 56 and its surroundings of the dust cover 12 when it is not attached, and Figure 3(b) is an enlarged cross-sectional view showing the tilt-suppression projection 56 and its surroundings of the dust cover 12 when it is attached.

[0013] Hereafter, for the sake of explanation, the side of the socket 30 on which the knuckle 40 is provided will be referred to as the upper side, and the opposite side as the lower side, in the direction along the central axis C1. However, the orientation in which the ball joint 100 is used is not particularly limited, and it can be used in any orientation.

[0014] The ball joint 100 is used, for example, in the suspension and steering systems of automobiles. The ball joint 100 comprises a joint mechanism 10 and a dust cover 12.

[0015] The joint mechanism 10 includes a ball stud 20, a socket 30, and a knuckle 40. The ball stud 20 is a rod-shaped member. The ball stud 20 has a cylindrical shaft portion 21 and a spherical spherical portion 22. The spherical portion 22 is provided at one end of the shaft portion 21.

[0016] The socket 30 is a component that supports the ball stud 20 so as to be rotatable and swingable. The socket 30 has a housing portion 31, a bottom plate 32, and a bearing portion 33.

[0017] The housing part 31 is, for example, a cylindrical member. At the upper end of the housing part 31, an annular and stepped fixing part 31a to which a fixed part 52 of the dust cover 12 is fixed as described later is formed. The fixing part 31a has a fitting surface (outer peripheral surface) 31b and a seating surface 31c. The fitting surface 31b is a cylindrical surface centered on the central axis C1. The seating surface 31c is a plane perpendicular to the central axis C1 and is a disk-shaped (i.e., a circular plate shape with a hole in the center) plane through which the central axis C1 passes at its center. At the lower end of the fitting surface 31b, the inner peripheral end of the seating surface 31c is continuous.

[0018] The housing part 31 has two upper surfaces, an inner upper surface 31d and an outer upper surface 31e. The outer upper surface 31e is located outside the inner upper surface 31d. The inner upper surface 31d is a plane perpendicular to the central axis C1 and is a disk-shaped plane through which the central axis C1 passes at its center. The outer upper surface 31e has the shape of a side surface of a truncated cone centered on the central axis C1.

[0019] The bottom plate 32 is a plate-shaped member that forms the bottom surface of the socket 30 by closing the opening on the lower end side of the housing part 31.

[0020] The bearing part 33 is accommodated in the space formed by the housing part 31 and the bottom plate 32. The bearing part 33 supports the spherical part 22 of the ball stud 20. Specifically, the bearing part 33 has a spherical bearing surface 34 with the same diameter as the radius of curvature of the spherical part 22. The ball stud 20 is supported by the bearing part 33 in a state where the surface of the spherical part 22 contacts the bearing surface 34. Grease is filled in the gap between the surface of the spherical part 22 and the bearing surface 34. Therefore, the ball stud 20 is rotatable about the central axis C2 of the shaft part 21 and is swingable in a state inclined with respect to the central axis C1 of the socket 30.

[0021] The knuckle 40 is an annular body integrally formed with the other end of the shaft part 21.

[0022] The dust cover 12 is a cylindrical member. The dust cover 12 prevents the intrusion of dust or moisture into the connecting part between the spherical part 22 and the bearing part 33 and the outflow of grease from the connecting part.

[0023] The dust cover 12 comprises a sealing portion (small diameter portion of the dust cover) 51, a fixed portion (large diameter portion of the dust cover) 52, a body portion 53, an upper reinforcing ring 54, a lower reinforcing ring 55, and a collapse suppression projection (hereinafter also simply referred to as "projection") 56 which acts as a collapse suppression portion to suppress collapse of the body portion 53. The sealing portion 51, the fixed portion 52, the body portion 53, and the projection 56 are integrally formed elastic materials such as rubber (for example, chloroprene rubber).

[0024] The sealing portion 51 is an annular body that forms one end of the cylindrical dust cover 12. The fixed portion 52 is an annular body that forms the other end of the cylindrical dust cover 12. The body portion 53 is a cylindrical body located between the sealing portion 51 and the fixed portion 52, and is integrally formed with them. The projection 56 is an annular projection that protrudes inward near the boundary between the body portion 53 and the fixed portion 52.

[0025] The sealing portion 51 surrounds the shaft portion 21. The sealing portion 51 is fitted to the outer circumferential surface 21a of the shaft portion 21, and, in the illustrated example, to the outer circumferential surface 21a of the shaft portion 21 opposite to the spherical portion 22 relative to the flange portion 23, and also in contact with the lower surface 40a of the knuckle 40. That is, the inner circumferential surface 51a of the sealing portion 51 is in close contact with the outer circumferential surface 21a of the shaft portion 21, and the upper end surface 50b of the sealing portion 51 is in close contact with the lower surface 40a of the knuckle 40. The flange portion 23 is the portion of the shaft portion 21 that protrudes in an annular shape outward from the surrounding portion in the direction along the central axis C2.

[0026] An annular upper reinforcing ring 54 is embedded inside the seal portion 51. The upper reinforcing ring 54 is made of, for example, resin or metal. The seal portion 51 is tightened to the shaft portion 21 by the upper reinforcing ring 54 and is firmly fixed to the shaft portion 21.

[0027] The fixed portion 52 constitutes the other end of the cylindrical dust cover 12. The fixed portion 52 is fixed to the socket 30. The lower surface 52a of the fixed portion 52 sits on the seating surface 31c of the fixing portion 31a of the housing portion 31, and the inner circumferential surface 52b fits into the fitting surface 31b of the fixing portion 31a of the housing portion 31.

[0028] An annular lower reinforcing ring 55 is embedded inside the fixed portion 52. The lower reinforcing ring 55 is made of, for example, resin or metal. The fixed portion 52 is tightened against the mating surface 31b by the lower reinforcing ring 55 and firmly fixed to the mating surface 31b.

[0029] It is also conceivable that the dust cover 12 may not have an upper reinforcing ring 54. In this case, instead of embedding the upper reinforcing ring 54 in the sealing portion 51, the sealing portion 51 may be tightened from the outer circumference with an annular fastener.

[0030] The body portion 53 surrounds the shaft portion 21 of the ball stud 20. The body portion 53 is a membrane that elastically deforms in conjunction with the rotation and oscillation of the ball stud 20 relative to the socket 30. When the ball stud 20 oscillates, the body portion 53 contracts on the side of the oscillating ball stud 20 (left side in Figure 1) and expands on the opposite side of the oscillating ball stud 20 (right side in Figure 1).

[0031] The projection 56 protrudes inward from the inner circumferential surface of the lower end of the body portion 53.

[0032] The dust cover 12 is molded, for example, by setting the upper reinforcing ring 54 and the lower reinforcing ring 55 in a predetermined mold and injecting a material such as rubber into the mold.

[0033] The above describes the basic configuration of the dust cover 12 and the ball joint 100 equipped therewith.

[0034] When the ball stud 20 rotates relative to the socket 30, the sealing portion 51 of the dust cover 12 slides against the shaft portion 21 of the ball stud 20. Also, when the ball stud 20 oscillates relative to the socket 30, the body portion 53 of the dust cover 12 deforms. Therefore, even when the ball stud 20 rotates or oscillates relative to the socket 30, the sealing function of the dust cover 12 is maintained.

[0035] The projection 56 of the dust cover 12 will be described in more detail with reference to Figures 3(a) and 3(b).

[0036] When the dust cover 12 is not installed, the height h1 (see Figure 3(a)) from the lower surface 52a of the fixed portion 52 to the lowest part of the projection 56 is lower than the height h2 (see Figure 3(b)) of the inner upper surface 31d of the housing portion 31, with the seating surface 31c as the reference surface. As a result, when the dust cover 12 is installed, the projection 56 presses against the housing portion 31 of the socket 30. Specifically, the projection 56 presses against the inner upper surface 31d, the outer upper surface 31e, or the mating surface 31b of the housing portion 31. Therefore, the projection 56 and thus the lower end of the body portion 53 are pushed outward, and the inward tilting of the housing portion 31 is suppressed.

[0037] Preferably, when the dust cover 12 is not installed, the height h1 (see Figure 3(a)) from the lower surface 52a of the fixed portion 52 to the lowest part of the projection 56 is lower than the height h3 (see Figure 3(b)) of the upper end of the fitted surface 31b with the seating surface 31c as the reference surface, i.e., the height h3 of the fitted surface 31b. In this case, when the dust cover 12 is installed, the projection 56 is pressed against the fitted surface 31b of the housing portion 31 or against the outer upper surface 31e of the housing portion 31 and pushed upward. In either case, the projection 56 and thus the lower end of the body portion 53 are pushed more strongly outward, and the inward tilting of the housing portion 31 is more reliably suppressed.

[0038] However, if the projection 56 is too thin, its rigidity will be low, and even if the projection 56 presses against the housing portion 31 of the socket 30, only the projection 56 will deform, and the body portion 53 will not be pushed outwards. Depending on the material, for example, the width W of the projection 56 on the dust cover 12 when not attached (see Figure 3(a)) may be 0.5 mm or more and 1.5 mm or less.

[0039] When the dust cover 12 is not attached, the inner diameter of the projection 56, that is, the inner diameter D1 of the part of the projection 56 located on the innermost circumference (see Figure 3(a)), is smaller than the outer diameter D2 of the mating surface 31b (see Figure 3(b)), preferably 2 mm or more smaller. When the inner diameter D1 is 2 mm or more smaller than the outer diameter D2, the projection 56 and, consequently, the lower end of the body portion 53 are pushed relatively strongly outward, more reliably suppressing the inward tilting of the housing portion 31.

[0040] When not attached, the projection 56 of the dust cover 12 may protrude inward and downward, as shown in Figure 3(a). As a result, when attached, the projection 56 of the dust cover 12 is pushed upward more strongly by the mating surface 31b or the outer upper surface 31e of the housing portion 31 compared to when it is not attached, that is, compared to when the projection 56 protrudes inward and upward when not attached. Consequently, the projection 56 and, by extension, the lower end of the body portion 53 are pushed more strongly outward, and the inward tilting of the housing portion 31 is more reliably suppressed.

[0041] When the dust cover 12 is not attached, the projection 56 may protrude inward from the boundary 58 between the body portion 53 and the fixed portion 52, as shown in Figure 3(a). Generally, when the lower reinforcing ring 55 is embedded in the fixed portion 52, when the dust cover 12 is attached, the mating surface 31b of the socket 30 exists at least up to the boundary 58 between the body portion 53 and the fixed portion 52. Therefore, if the projection 56 protrudes from the boundary 58, the projection 56 will reliably press against the mating surface 31b of the socket 30.

[0042] The projections 56 are typically formed continuously in the circumferential direction, i.e., in a ring shape. However, the projections 56 may be formed intermittently in the circumferential direction. For example, the projections 56 may be formed intermittently at equal intervals in the circumferential direction.

[0043] The inventors conducted simulations to verify the effect of the dust cover 12 being equipped with a projection 56 to prevent it from collapsing.

[0044] Figures 4(a) to 4(c) show the results of a simulation of how the dust cover 112 of the comparative example deforms due to the oscillation of the ball stud 20. The dust cover 112 of the comparative example is configured similarly to the dust cover 12 of this embodiment, except that it does not have the projection 56.

[0045] Figures 4(a), (b), and (c) show the cases where the oscillation angle θ is 0°, 15°, and 20°, respectively. When the oscillation angle θ is 0°, the central axis C2 of the shaft portion 21 of the ball stud 20 coincides with the central axis C1 of the socket 30. As shown in Figures 4(b) and (c), when the ball stud 20 oscillates, the side of the lower end of the body portion 53 that the ball stud 20 oscillates on (the left side in Figures 4(b) and (c)) tilts inward and comes into contact with the ball stud 20.

[0046] Figures 5(a) to 5(c) show the results of a simulation of how the dust cover 12 according to the embodiment deforms due to the oscillation of the ball stud 20.

[0047] Figures 5(a), (b), and (c) show the cases where the oscillation angle θ is 0°, 15°, and 20°, respectively. As shown in Figures 5(b) and (c), when the ball stud 20 oscillates, the side of the lower end of the body portion 53 on which the ball stud 20 oscillates (the left side in Figures 5(b) and (c)) does not tilt inward.

[0048] According to the above embodiment, the projection 56 presses against the inner upper surface 31d, the outer upper surface 31e, or the mating surface 31b of the housing portion 31. As a result, the projection 56 and, consequently, the lower end of the body portion 53 are pushed outward, preventing the housing portion 31 from collapsing inward, preventing contact between the body portion 53 and the ball stud 20, and thus preventing damage to the body portion 53.

[0049] Since only a projection 56 is provided on the inner circumferential surface, no special process is required for molding the dust cover 12 or for assembling the dust cover 12 to the joint mechanism 10, and conventional technology can be used as is.

[0050] The present disclosure has been described above based on embodiments. These embodiments are illustrative, and it will be understood by those skilled in the art that various modifications are possible in combinations of their components and processing processes, and that such modifications are also within the scope of the present disclosure.

[0051] The present disclosure has been described above based on embodiments. These embodiments are illustrative, and it will be understood by those skilled in the art that various modifications are possible in combinations of their components and processing processes, and that such modifications are also within the scope of the present disclosure. Such modifications will be described below.

[0052] The above embodiments and variations can be generalized to obtain the following embodiments.

[0053] [Aspect 1] A dust cover used in a ball joint, The ball joint comprises a ball stud having a shaft portion and a spherical portion provided at one end of the shaft portion, and a socket having a bearing portion that supports the spherical portion and that rotatably and swingably supports the ball stud. This dust cover is The part to be fixed to the socket, A sealing portion having an inner circumferential surface that contacts the outer circumferential surface of the shaft portion of the ball stud, A body portion located between the fixed portion and the sealing portion, which surrounds the shaft portion of the ball stud, Equipped with, A reinforcing ring is embedded in the fixed portion. This dust cover further comprises an annular tilt-preventing projection that protrudes from the inner circumferential surface of the end of the body portion on the fixed portion side, and which suppresses tilting of the body portion on the side on which the ball stud oscillates when the ball stud oscillates. Dust cover.

[0054] [Aspect 2] The aforementioned tilt-preventing projection presses against the socket. A dust cover as described in Embodiment 1.

[0055] [Aspect 3] When not installed, the tilt-preventing projection protrudes toward the inner circumference and toward the opposite side of the sealing portion in the axial direction. A dust cover according to embodiment 1 or 2.

[0056] [Aspect 4] The aforementioned tilt-preventing projection protrudes from the boundary between the body portion and the fixed portion. A dust cover according to any one of embodiments 1 to 3.

[0057] [Aspect 5] A dust cover used in a ball joint, The ball joint comprises a ball stud having a shaft portion and a spherical portion provided at one end of the shaft portion, and a socket having a bearing portion that supports the spherical portion and that rotatably and swingably supports the ball stud. This dust cover is The part to be fixed to the socket, A sealing portion having an inner circumferential surface that contacts the outer circumferential surface of the shaft portion of the ball stud, A body portion located between the fixed portion and the sealing portion, which surrounds the shaft portion of the ball stud, Equipped with, A reinforcing ring is embedded in the fixed portion. This dust cover is equipped with a tilt suppression part that suppresses the tilting of the body portion on the side of the ball stud that is tilted toward the inner circumference when the ball stud is tilted. Dust cover.

[0058] [Aspect 6] The aforementioned tilt-preventing portion is an annular projection that protrudes from the inner circumferential surface of the end of the body portion on the side of the fixed portion. The dust cover according to claim 5.

[0059] [Aspect 7] A ball joint comprising a dust cover according to any one of embodiments 1 to 6. [Explanation of Symbols]

[0060] 12 Dust cover, 20 Ball stud, 21 Shaft, 30 Socket, 31 Housing, 31a Fixing part, 31b Fitting surface, 31c Sealing surface, 51 Seal part, 52 Fixed part, 53 Body, 55 Lower reinforcing ring, 56 Anti-tilting projection, 100 Ball joint.

Claims

1. A dust cover used in a ball joint, The ball joint comprises a ball stud having a shaft portion and a spherical portion provided at one end of the shaft portion, and a socket having a bearing portion that supports the spherical portion and that rotatably and swingably supports the ball stud. This dust cover is The part to be fixed to the socket, A sealing portion having an inner circumferential surface that contacts the outer circumferential surface of the shaft portion of the ball stud, A body portion located between the fixed portion and the sealing portion, which surrounds the shaft portion of the ball stud, Equipped with, A reinforcing ring is embedded in the fixed portion. This dust cover further comprises an annular tilt-preventing projection that protrudes from the inner circumferential surface of the end of the body portion on the fixed portion side, and which suppresses tilting of the body portion on the side on which the ball stud oscillates when the ball stud oscillates. Dust cover.

2. The aforementioned tilt-preventing projection presses against the socket. The dust cover according to claim 1.

3. The aforementioned tilt-preventing projection, when not installed, protrudes toward the inner circumference and toward the opposite side of the sealing portion in the axial direction. The dust cover according to claim 1.

4. The aforementioned tilt-preventing projection protrudes from the boundary between the body portion and the fixed portion. The dust cover according to claim 1.

5. A dust cover used in a ball joint, The ball joint comprises a ball stud having a shaft portion and a spherical portion provided at one end of the shaft portion, and a socket having a bearing portion that supports the spherical portion and that rotatably and swingably supports the ball stud. This dust cover is The part to be fixed to the socket, A sealing portion having an inner circumferential surface that contacts the outer circumferential surface of the shaft portion of the ball stud, A body portion located between the fixed portion and the sealing portion, which surrounds the shaft portion of the ball stud, Equipped with, A reinforcing ring is embedded in the fixed portion. This dust cover is equipped with a tilt suppression part that suppresses the tilting of the body portion on the side of the ball stud that is tilted toward the inner circumference when the ball stud is tilted. Dust cover.

6. The aforementioned tilt-preventing portion is an annular projection that protrudes from the inner circumferential surface of the end of the body portion on the side of the fixed portion. The dust cover according to claim 5.

7. A ball joint comprising a dust cover according to any one of claims 1 to 6.

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