Dust cover and ball joint

Abstract

This dust cover 12 is used for a ball joint 100. The dust cover 12 includes a fixed part 52 fixed to a socket 30, a seal part 51 having an inner peripheral surface in contact with an outer peripheral surface of a shaft part 21 of a ball stud 20, and a body part 53 which is located between the fixed part 52 and the seal part 51 and which surrounds the shaft part 21 of the ball stud 20. The body part 53 has a bellows structure, and, when the ball stud 20 is tilted at a predetermined angle or more, is positioned on a central axis C2 side of the shaft part 21 of the ball stud 20 with respect to a tangent line L1 which touches the outer peripheral surface of a ridge which is the closest to the seal part 51 among a plurality of ridges, the tangent line L1 being parallel to the central axis C2.

Description

Dust cover and ball joint

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

[0002] Dust covers are used in ball joints installed in various devices such as vehicles to prevent water and dust from entering the joint and to prevent grease from leaking out from the joint. Conventionally, dust covers have been proposed, for example, as described in Patent Document 1.

[0003] Japanese Patent Application Laid-Open No. 2021-134899

[0004] As ball joints continue to grow larger, the space around the dust cover is becoming smaller. Repeated contact between the dust cover and other components of the ball joint or peripheral parts caused by the repeated rocking of the ball stud can cause the dust cover to deteriorate and potentially break. While it is possible to avoid this contact by shortening the membrane length of the dust cover's body, thereby reducing the dimensions of the body in the radial direction of the socket, this would result in a reduced sealing performance.

[0005] The present disclosure has been made in consideration of such problems, and one exemplary purpose of one aspect thereof is to provide a technology that can maintain relatively high sealing performance while reducing the risk of damage to the dust cover.

[0006] A dust cover according to one embodiment of the present disclosure is a dust cover for use in a ball joint, the ball joint comprising: a ball stud having a shank and a spherical portion provided at one end of the shank; a socket having a bearing portion that supports the spherical portion and supports the ball stud rotatably and pivotably; a fixed portion fixed to the socket; a seal portion having an inner peripheral surface that contacts the outer peripheral surface of the shank of the ball stud; and a body portion located between the fixed portion and the seal portion and surrounding the shank of the ball stud. When the ball stud pivots by a predetermined angle or more, the body portion exhibits a wave-like shape on the side where the ball stud pivots, and is located on the central axis side of a tangent line that is tangent to the outer peripheral surface of the peak closest to the seal portion and that is parallel to the central axis of the shank of the ball stud.

[0007] Another aspect of the present disclosure is a ball joint, the ball joint including the dust cover described above.

[0008] According to one aspect of the present disclosure, it is possible to maintain a relatively high sealing performance and reduce the risk of damage to the dust cover.

[0009] Fig. 2 is a cross-sectional view of a ball joint equipped with a dust cover according to an embodiment; Fig. 3 is a cross-sectional view of the dust cover of Fig. 1 when not attached; Fig. 4 is an enlarged cross-sectional view of the dust cover of Fig. 1 and its periphery; Fig. 5 is an enlarged cross-sectional view of the dust cover of Fig. 1 and its periphery;

[0010] Preferred embodiments will be described below with reference to the drawings. The embodiments are illustrative and do not limit the disclosure, and all features and combinations described in the embodiments are not necessarily essential to the disclosed invention. The same or equivalent components, parts, and processes shown in each drawing will be assigned the same reference numerals, and redundant descriptions will be omitted as appropriate.

[0011] Please refer to Figures 1 to 4. Figures 1, 3, and 4 show a cross section including the central axis C1 of the socket 30 and the central axis C2 of the shank 21 of the ball stud 20. Figures 1 and 4 show the ball stud 20 swung to the maximum relative to the socket 30, i.e., the swing angle θ of the ball stud 20 relative to the socket 30 is the maximum angle θ ｍａｘ The pivot angle θ is the acute angle formed by the central axes C1 and C2 in a cross section including the central axes C1 and C2. Fig. 3 shows the ball stud 20 standing upright relative to the socket 30. The ball stud 20 being upright means that the central axis C2 of the shank 21 of the ball stud 20 coincides with the central axis C1 of the socket 30, i.e., the ball stud 20 is not pivoting. Fig. 2 shows a cross section including the central axis of the dust cover 12 when not attached.

[0012] The ball joint 100 is used, for example, in a suspension system or a steering system of an automobile. The ball joint 100 includes a joint mechanism 10 and a dust cover 12.

[0013] 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 includes a cylindrical shank 21 and a spherical portion 22. The spherical portion 22 is provided at one end of the shank 21.

[0014] The socket 30 is a member that supports the ball stud 20 so that it can rotate and swing freely. The socket 30 has a housing portion 31, a bottom plate 32, and a bearing portion 33. The housing portion 31 is, for example, a cylindrical member. The bottom plate 32 is a plate-like member that closes the opening of the housing portion 31 and forms the bottom surface of the socket 30.

[0015] The bearing 33 is housed in the space formed by the housing 31 and the bottom plate 32. The bearing 33 supports the spherical portion 22 of the ball stud 20. Specifically, the bearing 33 has a spherical bearing surface 34 with a diameter equal to the radius of curvature of the spherical portion 22. The ball stud 20 is supported by the bearing 33 with the surface of the spherical portion 22 in contact with the bearing surface 34. Grease is filled in the gap between the surface of the spherical portion 22 and the bearing surface 34. Therefore, the ball stud 20 is rotatable about the central axis C2 of the shank 21 and is also pivotable at an angle relative to the central axis C1 of the socket 30.

[0016] The knuckle 40 is an annular body that is integrally formed with the other end of the shaft portion 21 .

[0017] The dust cover 12 is a cylindrical member that prevents dust or moisture from entering the connecting portion between the spherical portion 22 and the bearing portion 33 and prevents grease from leaking out from the connecting portion.

[0018] The dust cover 12 includes a sealing portion (dust cover small diameter portion) 51, a fixed portion (dust cover large diameter portion) 52, a body portion 53, an upper reinforcing ring 54, and a lower reinforcing ring 55. The sealing portion 51, the fixed portion 52, and the body portion 53 are integrally formed of an elastic body such as rubber (e.g., chloroprene rubber).

[0019] 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 that is located between the sealing portion 51 and the fixed portion 52 and is formed integrally with them.

[0020] The seal portion 51 surrounds the shaft portion 21. The seal portion 51 is fitted to the outer peripheral surface 21a of the shaft portion 21, or, if the shaft portion 21 has a flange portion 23 as in the illustrated example, to the outer peripheral surface 21a of the shaft portion 21 on the opposite side of the spherical portion 22 with respect to the flange portion 23, and is also in contact with the underside 40a of the knuckle 40. That is, the inner peripheral surface 51a of the seal portion 51 is in close contact with the outer peripheral surface of the shaft portion 21, and the upper end surface 50b of the seal portion 51 is in close contact with the underside 40a of the knuckle 40. The flange portion 23 is a 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.

[0021] 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 fastened to the shaft portion 21 by the upper reinforcing ring 54, and is firmly fixed to the shaft portion 21.

[0022] The fixed portion 52 constitutes the other end of the cylindrical dust cover 12. The fixed portion 52 is fitted into the socket 30. The fixed portion 52 surrounds the upper end of the housing portion 31 and is fitted onto the outer peripheral surface of the upper end. The inner peripheral surface of the fixed portion 52 is in close contact with the outer peripheral surface of the upper end of the housing portion 31. 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 fastened to the upper end of the housing portion 31 by the lower reinforcing ring 55 and is firmly fixed to the upper end of the housing portion 31.

[0023] It is also possible to consider a configuration in which the dust cover 12 does not include at least one of the upper reinforcing ring 54 and the lower reinforcing ring 55. For example, instead of embedding a reinforcing ring, the sealing portion 51 and the fixed portion 52 may be fastened from the outer periphery with an annular fastener.

[0024] The body portion 53 surrounds the shank 21 of the ball stud 20. The body portion 53 is a membrane that elastically deforms in response to the rotation and pivoting of the ball stud 20 relative to the socket 30. When the ball stud 20 pivots, the body portion 53 contracts on the side where the ball stud 20 pivots (the left side in FIGS. 1 and 3) and expands on the side opposite the side where the ball stud 20 pivots (the right side in FIGS. 1 and 3). To achieve this, the cross section of the body portion 53, including its central axis, has a wave shape with its amplitude generally perpendicular to the central axis when the dust cover 12 is not attached (see FIG. 2) and when the ball stud 20 is upright with the dust cover 12 attached (see FIG. 3). Specifically, the body portion 53 has a wave shape including a first peak portion 531 , a second peak portion 532 , and a valley portion 533 located between the first peak portion 531 and the second peak portion 532 .

[0025] The first peak 531 is an annular portion that is continuous with the seal portion 51. The second peak 532 is an annular portion that is continuous with the fixed portion 52. The first peak 531 and the second peak 532 have a cross-sectional shape that is convex on the side opposite the central axis C1, in other words, on the outer periphery of the dust cover 12. The first peak 531 and the second peak 532 can also be described as mountain-shaped portions when viewed from the outside of the body portion 53.

[0026] The valley portion 533 is located between the first peak portion 531 and the second peak portion 532 and is an annular portion that is continuous with each of the first peak portion 531 and the second peak portion 532. The valley portion 533 has a cross-sectional shape that is convex toward the central axis C1, in other words, toward the inner periphery of the dust cover 12. The valley portion 533 can also be described as a valley-shaped portion when viewed from the outside of the body portion 53. The valley portion 533 has a smaller diameter than the first peak portion 531 and the second peak portion 532.

[0027] When the ball stud 20 pivots, the body 53 on the side where the ball stud 20 pivots deforms or contracts, with the first crest 531, second crest 532, and valley 533 crushing in a direction generally along the central axis C2 and the first crest 531 and second crest 532 moving closer together, and on the side opposite the side where the ball stud 20 pivots, the first crest 531, second crest 532, and valley 533 expanding in a direction generally along the central axis C2 and the first crest 531 and second crest 532 moving apart. Therefore, when the ball stud 20 pivots, the body on the side where the ball stud 20 pivots exhibits a wave shape.

[0028] By employing a corrugated body portion 53, it is possible to make the dimension of the body portion 53 relatively small in the radial direction X (i.e., the direction perpendicular to the central axis C1) of the socket 30. Furthermore, because the body portion 53 has a corrugated shape, it is possible to make the membrane length of the body portion 53 long while making the dimension of the body portion 53 relatively small in the radial direction X, thereby achieving stable sealing performance.

[0029] The above is the basic configuration of the dust cover 12 and the ball joint 100 equipped with it.

[0030] When the ball stud 20 rotates relative to the socket 30, the seal portion 51 of the dust cover 12 slides against the shaft portion 21 of the ball stud 20. When the ball stud 20 swings relative to the socket 30, the body portion 53 of the dust cover 12 deforms. Therefore, even when the ball stud 20 rotates or swings relative to the socket 30, the dust cover 12 maintains its sealing function.

[0031] Next, the dust cover 12 will be described in detail.

[0032] The dust cover 12 has the following feature (A), and preferably has at least one of the features (B) to (E).

[0033] (A) Refer to FIG. 4. The dust cover 12 is attached to the ball stud 20 at a predetermined angle θ ｔｈ During the above swinging, that is, when the ball stud 20 is swinging, the swing angle θ of the ball stud 20 relative to the socket 30 is angle θｔｈ In this case, in a cross section including the central axis C1 and the central axis C2, the entire body portion 53 is configured to be located on the central axis C2 side of a tangent line L1 that is tangent to the outer peripheral surface 531a of the first crest 531 and is parallel to the central axis C2 of the shank 21 of the ball stud 20. In other words, the dust cover 12 is configured to be "positioned so that the angle θ of the ball stud 20 is ｔｈ During the above swinging, the second peak portion 532 is configured not to protrude beyond the tangent line L1 to the side opposite the central axis C2 in a cross section including the central axis C1 and the central axis C2.

[0034] As a non-limiting example, the angle θ ｔｈ is 20°, and the maximum angle θ ｍａｘ may be 30°.

[0035] When the feature (A) is provided, if the membrane length of the body portion 53 is relatively short, contact between the body portion 53 and the socket 30 can be avoided as shown in FIG.

[0036] When the feature (A) is provided, if the membrane length of the body portion 53 is relatively long, the body portion 53 comes into contact with the socket 30. Here, the angle θ of the ball stud 20 ｔｈ If the second crest 532 protrudes from the tangent line L1 toward the opposite side of the central axis C2 during the above-described pivoting motion, the second crest 532 is pinched relatively tightly between the first crest 531 and the socket 30 each time the ball stud 20 pivots, and the second crest 532 is therefore prone to deterioration. ｔｈ If the second peak portion 532 does not protrude toward the opposite side of the central axis C2 from the tangent line L1 during the above-described swinging motion, the second peak portion 532 will not be sandwiched between the first peak portion 531 and the socket 30, or will be sandwiched relatively weakly, and therefore the second peak portion 532 will not deteriorate easily.

[0037] In any case, if the dust cover 12 has the feature (A), it will be less likely to be damaged.

[0038] In addition, the angle θ ｔｈ is the maximum angle θ ｍａｘ Typically, the maximum angle θ ｍａｘ Therefore, in the configuration of the feature (A), the angle θ ｔｈ"When the oscillation is greater than θ" is defined as "when the oscillation is maximum (i.e., θ = θ ｍａｘ (in the case of

[0039] (B) The dust cover 12 is attached to the ball stud 20 at an angle θ ｔｈ During the above swinging motion, in a cross section including the central axes C1 and C2, the entire body portion 53 is positioned on the opposite side of the central axis C2 with respect to a tangent line L2 that is tangent to the inner peripheral surface of the seal portion 51 and is parallel to the central axis C2 of the shank 21 of the ball stud 20. Note that when the shank 21 has a flange 23, the dust cover 12 is configured to be "positioned so that the angle θ of the ball stud 20 is ｔｈ During the above swinging motion, in a cross section including the central axis C1 and the central axis C2, the entire body portion 53 may be configured to be positioned on the opposite side of the central axis C2 with respect to a tangent line L3 that contacts the outer peripheral surface of the flange portion 23 and is parallel to the central axis C2 of the shank 21 of the ball stud 20.

[0040] Here, if the body portion 53 is pinched between the shaft portion 21 of the ball stud 20 and the housing portion 31 of the socket 30 when the ball stud 20 swings, the body portion 53 may be cut, or may deteriorate and break as it is repeatedly pinched.

[0041] In contrast, when feature (B) is provided, the entire body 53 of the dust cover 12 is located on the opposite side of the tangent line L2 or L3 from the central axis C2 of the shank 21 of the ball stud 20. As a result, the body 53 does not come into contact with the shank 21 of the ball stud 20 even when the ball stud 20 pivots by a predetermined angle or more, and therefore the body 53 is prevented from being pinched between the shank 21 of the ball stud 20 and the housing 31 of the socket 30.

[0042] Again, the angle θ ｔｈ is the maximum angle θ ｍａｘ Typically, the maximum angle θ ｍａｘ Therefore, in the configuration of the feature (B), the angle θ ｔｈ "When the oscillation is greater than θ" is defined as "when the oscillation is maximum (i.e., θ = θ ｍａｘ (in the case of

[0043] (C) The seal portion 51 and the body portion 53 of the dust cover 12 are in contact with the ball stud 20 when the ball stud 20 is upright and when the ball stud 20 is oscillating (at an angle θ ｔｈ Even during the above-described swinging motion, the seal portion 51 and the body portion 53 are not in contact with the flange 23 of the shaft 21 of the ball stud 20. In this case, deterioration of the seal portion 51 and the body portion 53 due to repeated contact with the flange 23 can be avoided.

[0044] (D) Refer to Figure 2. The dust cover 12 is preferably formed to satisfy the following formulas (1) and (2) when not attached. In this case, when the dust cover 12 is attached, the dimension of the body portion 53 in the radial direction X becomes relatively small. d1 > d3 ... (1) d2 > d3 ... (2) where, d1: maximum inner diameter of the first peak portion 531 when not attached, d2: maximum inner diameter of the second peak portion 532 when not attached, and d3: minimum inner diameter d3 of the valley portion 533 when not attached.

[0045] (E) See Figure 3. The dust cover 12 is formed to satisfy the following formulas (3) and (4) when the ball stud 20 is upright. In this case, the outer diameter of the body portion 53 of the dust cover 12 when attached is relatively small. d4>d6>d5 (3) d8>d7 (4) where, d4: outer diameter of the fixed portion 52 when attached d5: maximum outer diameter of the first peak portion 531 when attached d6: maximum outer diameter of the second peak portion 532 when attached d7: inner diameter of the seal portion 51 when attached d8: minimum outer diameter of the valley portion 533 when attached

[0046] The present disclosure has been described above based on the embodiments. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of the respective components and processing steps, and that such modifications are also within the scope of the present disclosure.

[0047] The present disclosure has been described above based on the embodiments. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of the respective components and processing steps, and that such modifications are also within the scope of the present disclosure. Such modifications will be described below.

[0048] In the embodiment, as shown in FIGS. 2 and 3, the cross section of the body portion 53 including its central axis has a wave shape with the amplitude direction generally perpendicular to the central axis when the dust cover 12 is not attached and when the ball stud 20 is upright with the dust cover 12 attached. However, the present invention is not limited to this, and the body portion 53 may have a wave shape with the amplitude direction generally perpendicular to the central axis when the dust cover 12 is not attached and when the ball stud 20 is upright. ｔｈ During the above swinging motion, it is sufficient that the portion of the body on the side where the ball stud 20 swings exhibits a wave shape including the first crest 531, the second crest 532, and the valley 533. In other words, the body 53 does not have to be wave-shaped when the dust cover 12 is not attached and when the ball stud 20 is upright with the dust cover 12 attached.

[0049] The above-described embodiment and modifications can be generalized to obtain the following aspects.

[0050] [Aspect 1] A dust cover for use in a ball joint, wherein the ball joint comprises: a ball stud having a shank and a spherical portion provided at one end of the shank; and a socket having a bearing portion that supports the spherical portion and supporting the ball stud so that it can rotate and swing freely; a fixed portion fixed to the socket; a seal portion having an inner peripheral surface that contacts the outer peripheral surface of the shank of the ball stud; and a body portion located between the fixed portion and the seal portion and surrounding the shank of the ball stud, wherein when the ball stud swings by a predetermined angle or more, the body portion has a wave-like shape on the side where the ball stud swings, and is located on the central axis side of a tangent line that is tangent to the outer peripheral surface of the peak closest to the seal portion, and which is parallel to the central axis of the shank of the ball stud.

[0051] [Aspect 2] The dust cover according to aspect 1, wherein the body portion is located closer to the central axis than the tangent line when the ball stud swings to a maximum extent.

[0052] [Aspect 3] The dust cover according to Aspect 1, wherein the body portion is located on the opposite side of a tangent line that contacts the inner peripheral surface of the seal portion and is parallel to the central axis of the ball stud when the ball stud pivots by the predetermined angle or more.

[0053] [Aspect 4] The dust cover according to aspect 1, wherein the seal portion and the body portion are out of contact with the flange portion of the shank of the ball stud when the ball stud pivots by the predetermined angle or more.

[0054] [Aspect 5] A ball joint equipped with the dust cover according to any one of aspects 1 to 4.

[0055] The present disclosure relates to a dust cover and a ball joint.

[0056] 12 Dust cover, 20 Ball stud, 21 Shaft portion, 30 Socket, 51 Sealing portion, 52 Fixed portion, 53 Body portion, 100 Ball joint, 531 First crest portion, 532 Second crest portion, 533 Root portion.

Claims

1. A dust cover for use in a ball joint, the ball joint comprising: a ball stud having a shaft portion and a spherical portion attached to one end of the shaft portion; a socket having a bearing portion that supports the spherical portion and supporting the ball stud so that it can rotate and swing freely; a fixed portion fixed to the socket; a seal portion having an inner peripheral surface that contacts the outer peripheral surface of the shank of the ball stud; and a body portion located between the fixed portion and the seal portion and surrounding the shank of the ball stud, wherein when the ball stud swings by a predetermined angle or more, the body portion has a wave-like shape on the side where the ball stud swings, and is located on the central axis side of a tangent line that is tangent to the outer peripheral surface of the peak closest to the seal portion and is parallel to the central axis of the shank of the ball stud.

2. A dust cover according to claim 1, wherein the body portion is located on the central axis side of the tangent line when the ball stud swings to its maximum extent.

3. A dust cover as described in claim 1, wherein the body portion is located on the opposite side of a tangent line that contacts the inner surface of the seal portion and is parallel to the central axis of the ball stud when the ball stud swings by more than the specified angle.

4. A dust cover according to claim 1, wherein the seal portion and the body portion are not in contact with the flange portion of the shank of the ball stud when the ball stud swings by more than the predetermined angle.

5. A ball joint equipped with a dust cover according to any one of claims 1 to 4.

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