JP7400482B2 - Dust cover and ball joint - Google Patents

Description

The present invention relates to a dust cover and a ball joint.

For example, a ball joint installed in various devices such as an automobile includes a ball stud having a spherical portion installed at one end, and a socket including a bearing portion that supports the spherical portion. A dust cover is installed on the ball joint to prevent dust and moisture from adhering to it and preventing grease from flowing out. For example, Patent Document 1 discloses a configuration in which a dust cover is formed into a bellows shape in order to ensure followability to the rocking motion of a ball stud.

International Publication No. 2019/058796

However, in a configuration in which the dust cover is formed in a bellows shape, the dust cover may deform so as to bulge upward. When the dust cover is deformed upward, the knuckle fixed to the ball stud may come into contact with the outer peripheral surface of the dust cover. In consideration of the above circumstances, an object of the present invention is to suppress contact of the knuckle with the dust cover.

A dust cover according to one aspect of the present invention includes a ball stud including a shaft portion in which a flange is formed and a spherical portion installed at one end of the shaft portion, and a bearing portion 33 that supports the spherical portion. An elastically deformable dust cover used for a ball joint comprising a socket, a fixed part fixed to the socket, and a seal part having an inner circumferential surface in contact with an outer circumferential surface of the shaft part. , a body part located between the fixed part and the seal part, and a connecting part located between the body part and the seal part are integrally formed, and the body part is located between the fixed part and the seal part. a first portion that is continuous with the first portion, a second portion that is located between the first portion and the connecting portion, and a second portion that is located between the first portion and the second portion, and that is continuous with the first portion and the a third portion protruding toward the ball stud side with respect to the two portions, and an inner circumferential surface of the connecting portion intersects with a first stepped surface facing the outer circumferential surface of the collar portion and the first stepped surface. an annular first step portion including a first base surface; an annular second step portion including a second step surface protruding from the first base surface and a second base surface intersecting the second step surface; including.

A ball joint according to one aspect of the present invention is a ball joint that includes a joint mechanism and a dust cover, and the joint mechanism includes a shaft portion on which a flange is formed and a shaft portion installed at one end of the shaft portion. The dust cover includes a ball stud including a spherical part and a socket including a bearing part 33 that supports the spherical part, and the dust cover contacts a fixed part fixed to the socket and an outer peripheral surface of the shaft part. A seal portion having an inner circumferential surface, a body portion located between the fixed portion and the seal portion, and a connecting portion located between the body portion and the seal portion are integrally formed, and the The body portion includes a first portion continuous to the fixed portion, a second portion located between the first portion and the connecting portion, and a second portion located between the first portion and the second portion. , a third portion protruding toward the ball stud with respect to the first portion and the second portion; an annular first step portion including a first base surface intersecting the first step surface; a second step surface protruding from the first base surface; and a second base surface intersecting the second step surface. and an annular second step portion.

According to the present invention, contact of the knuckle with the dust cover can be suppressed.

FIG. 1 is a cross-sectional view illustrating the configuration of a ball joint according to an embodiment. FIG. 3 is a sectional view of the dust cover. FIG. 3 is an enlarged cross-sectional view of a connecting portion of the dust cover. FIG. 3 is a partially enlarged cross-sectional view of the dust cover in an attached state. FIG. 3 is a cross-sectional view for explaining the problem of comparison. FIG. 3 is a cross-sectional view for explaining the effects of the embodiment.

Preferred embodiments of the present invention will be described below with reference to the drawings. Note that the dimensions and scale of each element in each drawing are appropriately different from the actual product.

A: Embodiment FIG. 1 is a cross-sectional view illustrating the configuration of a ball joint 100 according to a preferred embodiment of the present invention. The ball joint 100 of this embodiment is a structure used in various devices such as a suspension system or a steering system of an automobile. As illustrated in FIG. 1, the ball joint 100 includes a joint mechanism 11 and a dust cover 12.

The joint mechanism 11 is a mechanism that includes a ball stud 20, a socket 30, and a knuckle 40. A cross section through the central axis of the socket 30 is shown in FIG.

The ball stud 20 is a rod-shaped structure that includes a cylindrical shaft portion 21 and a spherical spherical portion 22 . The spherical part 22 is installed at one end of the shaft part 21. The shaft portion 21 is formed with a flange portion 23 that protrudes from the outer circumferential surface. The flange portion 23 is an annular projection along the circumferential direction of the shaft portion 21 . The knuckle 40 is a coupling member connected to an end of the shaft portion 21 on the opposite side to the spherical portion 22 with the collar portion 23 interposed therebetween.

The socket 30 is a structure that supports the ball stud 20 in a rotatable and swingable state. Specifically, the socket 30 includes a housing portion 31, a bottom plate 32, and a bearing portion 33. The housing portion 31 is, for example, a cylindrical structure. The bottom plate 32 is a plate-like member that forms the bottom surface of the socket 30 by closing the opening of the housing portion 31 .

The bearing portion 33 is accommodated in a space formed by the housing portion 31 and the bottom plate 32, and supports the spherical portion 22 of the ball stud 20. Specifically, a spherical bearing surface 34 having the same diameter as the radius of curvature of the spherical portion 22 is formed in the bearing portion 33 . The ball stud 20 is supported by the bearing portion 33 with the surface of the spherical portion 22 in contact with the bearing surface 34 . The gap between the surface of the spherical portion 22 and the bearing surface 34 is filled with grease. Therefore, the ball stud 20 is rotatable about the central axis of the shaft portion 21 and swingable at an angle with respect to the central axis of the socket 30.

The dust cover 12 is a structure installed on the joint mechanism 11 in order to prevent dust or moisture from adhering to the connecting portion between the spherical portion 22 and the bearing portion 33 and preventing grease applied to the connecting portion from flowing out. . The dust cover 12 is a cylindrical elastic body made of an elastic material such as rubber (for example, chloroprene rubber). Generally speaking, the dust cover 12 is installed to surround the ball stud 20.

FIG. 2 is a sectional view of the dust cover 12 in a state where it is not installed on the joint mechanism 11 (hereinafter referred to as "uninstalled state"). As illustrated in FIG. 2, the dust cover 12 of this embodiment is an elastic body in which a fixed portion 51, a seal portion 52, a body portion 53, and a connecting portion 54 are integrally formed. In FIG. 2, a central axis C of the dust cover 12 is illustrated.

The fixed portion 51 constitutes one end of the dust cover 12 in the direction of the central axis C. The seal portion 52 constitutes the other end of the dust cover 12 in the direction of the central axis C. The body portion 53 and the connecting portion 54 are located between the fixed portion 51 and the seal portion 52. Specifically, the body portion 53 is continuous with the fixed portion 51 and the connecting portion 54 is continuous with the seal portion 52. That is, the connecting portion 54 is located between the body portion 53 and the seal portion 52. The body portion 53 and the connecting portion 54 are continuous with each other.

As illustrated in FIG. 1, the fixed portion 51 is fixed to the socket 30. Specifically, the fixed portion 51 is an annular portion surrounding the end portion of the housing portion 31 . The fixed portion 51 is tightened from the outer circumferential side by a tightening member 61. The tightening member 61 is an annular member attached to the outer circumferential surface of the fixed portion 51 so as to surround the fixed portion 51 . For example, a circlip or a band is exemplified as the tightening member 61. By tightening from the tightening member 61, the fixed portion 51 is fixed to the socket 30 with the inner circumferential surface of the fixed portion 51 in close contact with the outer circumferential surface of the housing portion 31.

The seal portion 52 is an annular portion surrounding the shaft portion 21 . Specifically, the seal portion 52 surrounds a portion of the shaft portion 21 on the side opposite to the spherical portion 22 with respect to the collar portion 23 . A lip portion 521 is formed on the surface of the seal portion 52 facing the knuckle 40 and protrudes from the surface. The tip of the lip portion 521 contacts the surface of the knuckle 40.

The seal portion 52 is tightened from the outer circumferential side by a tightening member 62. The tightening member 62 is an annular member attached to the outer peripheral surface of the seal portion 52 so as to surround the seal portion 52 . For example, a circlip or a band is exemplified as the tightening member 62. Due to the tightening from the tightening member 62, the inner circumferential surface of the seal portion 52 is maintained in close contact with the outer circumferential surface of the shaft portion 21. As described above, the ball stud 20 is rotatable while being in close contact with the inner circumferential surface of the seal portion 52.

The body portion 53 is a membrane-like portion that elastically deforms in conjunction with the rotation and rocking of the ball stud 20 relative to the socket 30. As illustrated in FIG. 2, the body portion 53 of this embodiment is formed in a bellows shape including a first portion 531, a second portion 532, and a third portion 533. The first portion 531 is an annular portion continuous with the fixed portion 51 . The second portion 532 is an annular portion continuous to the connecting portion 54. That is, the second portion 532 is located between the first portion 531 and the connecting portion 54. The first portion 531 and the second portion 532 are convex portions that protrude toward the side opposite to the central axis C (that is, to the outside in the radial direction). That is, the first portion 531 and the second portion 532 can also be referred to as mountain-shaped portions when viewed from the outside of the body portion 53.

The third portion 533 is an annular portion located between the first portion 531 and the second portion 532. Specifically, the third portion 533 is continuous with each of the first portion 531 and the second portion 532. The third portion 533 is a convex portion that protrudes toward the central axis C side (that is, radially inward). That is, the third portion 533 can also be referred to as a valley-shaped portion when viewed from the outside of the body portion 53. As understood from the above description, the third portion 533 protrudes toward the ball stud 20 with respect to the first portion 531 and the second portion 532. The third portion 533 can also be referred to as a portion having a smaller diameter than the first portion 531 and the second portion 532. According to the configuration in which the body portion 53 is formed in a bellows shape as described above, there is an advantage that the amount of deformation of the dust cover 12 can be secured while suppressing the outer shape of the dust cover 12.

The connecting portion 54 is an annular portion that connects the body portion 53 and the seal portion 52. That is, the connecting portion 54 is continuous with each of the body portion 53 and the seal portion 52. FIG. 3 is an enlarged cross-sectional view of the vicinity of the connecting portion 54. As shown in FIG. As illustrated in FIGS. 2 and 3, the inner circumferential surface of the connecting portion 54 has a stepped structure including a first stepped portion 541 and a second stepped portion 542.

The first step portion 541 is a step portion including a first step surface S1 and a first base surface F1. The first step surface S1 is a circular arc surface centered on the central axis C. As illustrated in FIG. 1, the first step surface S1 faces the outer circumferential surface of the collar portion 23 in the shaft portion 21. As illustrated in FIG. Specifically, the first step surface S1 is in close contact with the outer circumferential surface of the collar portion 23. That is, the outer circumferential surface of the flange portion 23 is covered with the first step surface S1. As illustrated in FIG. 3, the inner diameter D1 of the first stepped surface S1 exceeds the inner diameter D0 of the seal portion 52 (D1>D0). According to the configuration in which the outer circumferential surface of the flange portion 23 is covered with the first step surface S1 as described above, the possibility that the inner circumferential surface of the body portion 53 comes into contact with the flange portion 23 is reduced.

The first base surface F1 of the first step portion 541 is a surface (a plane or a curved surface) that intersects the first step surface S1. The first base surface F1 of this embodiment is a flat surface perpendicular to the central axis C, and is formed in an annular shape centered on the central axis C. The inner diameter of the first base surface F1 corresponds to the inner diameter D1 of the first stepped surface S1.

The second step portion 542 is a step portion including a second step surface S2 and a second base surface F2. The second stepped surface S2 is a circular arc surface centered on the central axis C. The second stepped surface S2 protrudes from the first base surface F1. As illustrated in FIG. 1, the second stepped surface S2 faces the outer circumferential surface of the shaft portion 21 with an interval therebetween. Specifically, the second stepped surface S2 faces the outer circumferential surface of the shaft portion 21 between the collar portion 23 and the spherical portion 22. As illustrated in FIG. 3, the inner diameter D2 of the second step surface S2 exceeds the inner diameter D1 of the first step surface S1 (D2>D1).

The second base surface F2 is a surface (a plane or a curved surface) that intersects the second step surface S2. The second base surface F2 of this embodiment is a flat surface perpendicular to the central axis C, and is formed in an annular shape centered on the central axis C. The inner diameter of the second base surface F2 corresponds to the inner diameter D2 of the second stepped surface S2. The second base surface F2 is continuous with the inner circumferential surface of the body portion 53 (second portion 532). The second base surface F2 presses the inner circumferential surface of the third portion 533 in the process of the ball stud 20 swinging relative to the socket 30.

As illustrated in FIG. 3, the height H2 of the second stepped surface S2 (that is, the dimension in the direction parallel to the central axis C) exceeds the height H1 of the first stepped surface S1 (H2>H1). Further, the width W2 of the second base surface F2 (the radial dimension centered on the central axis C) exceeds the width W1 of the first base surface F1 (W2>W1). The height H1 and the height H2 are set to, for example, 0.5 mm or more, and the width W1 and the width W2 are set to, for example, 0.5 mm or more. However, the dimensions regarding each surface are not limited to the above examples.

As understood from FIG. 2, the outer circumferential surface of the connecting portion 54 in the unattached dust cover 12 is inclined with respect to the central axis C. Specifically, as understood from FIG. 3, the outer circumferential surface of the connecting portion 54 is an inclined surface in which the circumferential edge E1 on the seal portion 52 side has a smaller diameter than the circumferential edge E2 on the body portion 53 side. The outer circumferential surface of the connecting portion 54 can also be referred to as a sloped surface that is closer to the knuckle 40 (that is, farther from the spherical portion 22) as the position is closer to the seal portion 52. On the other hand, the second base surface F2 of the dust cover 12 in the unattached state is a flat surface perpendicular to the central axis C, as described above. Therefore, as illustrated in FIG. 3, the thickness T of the connecting portion 54 in the direction of the central axis C continuously increases from the peripheral edge E2 of the connecting portion 54 on the body portion 53 side to the second step surface S2. According to the above configuration, the third portion 533 is pressed by the second base surface F2 compared to a configuration in which the second base surface F2 is an inclined surface that is farther from the spherical part 22 as the position nearer to the second step surface S2 increases. easy.

FIG. 4 is a partially enlarged sectional view of the dust cover 12 in a state where it is mounted on the joint mechanism 11 (hereinafter referred to as the "mounted state"). FIG. 4 illustrates a state in which the ball stud 20 stands upright with respect to the socket 30 (hereinafter referred to as the "upright state"). The upright state is a state in which the central axis of the shaft portion 21 and the central axis of the socket 30 are parallel (that is, a state in which the ball stud 20 is not swinging).

As illustrated in FIG. 4, the second base surface F2 of the dust cover 12 in the installed state contacts the inner circumferential surface of the third portion 533 of the body portion 53 in the upright state. Further, the second base surface F2 of the dust cover 12 in the attached state is inclined with respect to the central axis C. Specifically, the second base surface F2 in the attached state is an inclined surface that is closer to the spherical portion 22 (that is, farther from the knuckle 40) as the position closer to the second step surface S2. That is, the second base surface F2 in this embodiment is a surface perpendicular to the central axis C of the dust cover 12 (uninstalled state), or an inclined surface closer to the spherical portion 22 at a position closer to the second stepped surface S2. (installed state). According to the above configuration, the third portion 533 is pressed by the second base surface F2, compared to a configuration in which the second base surface F2 is an inclined surface that is farther from the spherical part 22 at a position closer to the second step surface S2. It has the advantage of being easy to use.

FIG. 5 is a sectional view of the dust cover 12 in an attached state in a configuration in which the second stepped portion 542 is not formed on the inner circumferential surface of the connecting portion 54 (hereinafter referred to as a “comparison example”). In comparison, there is a tendency that sufficient rigidity of the connecting portion 54 cannot be ensured. In a configuration in which the rigidity of the connecting portion 54 is insufficient, the second portion 532 of the body portion 53 may undergo deformation (hereinafter referred to as “upward deflection”) in which the second portion 532 of the body portion 53 bulges toward the knuckle 40 in the process of inclining the ball stud 20. ) may occur. When the upward deflection occurs, the knuckle 40 comes into contact with the outer peripheral surface of the second portion 532, as indicated by the symbol α in FIG. In a configuration where upward deflection is likely to occur as described above, there is room for improvement in the durability of the dust cover 12 (second portion 532). Further, in a configuration in which the rigidity of the connecting portion 54 is not sufficiently ensured, there is a possibility that the dust cover 12 is twisted in conjunction with the rotation of the ball stud 20. Although it is possible to suppress upward deflection by ensuring a sufficient overall film thickness of the connecting portion 54, this time the rigidity of the connecting portion 54 becomes excessive, resulting in moderate deformation of the dust cover 12. becomes difficult.

FIG. 6 is a partially enlarged sectional view of the dust cover 12 of this embodiment. In FIG. 6, a state in which the ball stud 20 is swung relative to the socket 30 is illustrated. In this embodiment, in addition to the first step portion 541 , a second step portion 542 is formed on the inner circumferential surface of the connecting portion 54 . Therefore, the rigidity of the connecting portion 54 is ensured appropriately. Further, during the swinging process of the ball stud 20, the second base surface F2 presses the inner circumferential surface of the third portion 533. Therefore, as illustrated in FIG. 6, the upward deflection of the second portion 532 of the body portion 53 is suppressed compared to the comparative example of FIG. That is, the possibility that the knuckle 40 comes into contact with the outer peripheral surface of the second portion 532 is reduced. Therefore, according to this embodiment, it is possible to ensure sufficient durability of the dust cover 12. Further, according to the present embodiment, a step-like structure including the first step portion 541 and the second step portion 542 is formed on the inner circumferential surface of the connecting portion 54. Therefore, the rigidity of the connecting portion 54 is suppressed compared to a configuration in which the entire thickness of the connecting portion 54 is ensured sufficiently, and as a result, it is possible to appropriately deform the dust cover 12.

B: Modifications Specific modifications added to each of the embodiments exemplified above will be exemplified below. Two or more aspects arbitrarily selected from the examples below may be combined as appropriate to the extent that they do not contradict each other.

(1) In the above embodiment, the first stepped portion 541 and the second stepped portion 542 are formed on the inner peripheral surface of the connecting portion 54, but three or more stepped portions may be formed on the inner peripheral surface of the connecting portion 54. You can. In a configuration in which three or more step portions are formed on the inner circumferential surface of the connecting portion 54, two step portions selected from the two or more step portions are referred to as a “first step portion” and a “second step portion”. ”.

(2) In the above embodiment, the second base surface F2 of the dust cover 12 is in contact with the inner circumferential surface of the third portion 533 in the upright state. A configuration in which the inner circumferential surface of the portion 533 is not contacted is also adopted.

(3) In the above embodiment, the height H2 of the second stepped surface S2 exceeds the height H1 of the first stepped surface S1, but the relationship between the height H1 and the height H2 is as shown in the above example. but not limited to. For example, a configuration in which the height H2 is less than the height H1, or a configuration in which the height H2 and the height H1 are equivalent is also envisaged. Further, in the above-described embodiment, a configuration is illustrated in which the width W2 of the second base surface F2 exceeds the width W1 of the first base surface F1, but the relationship between the width W1 and the width W2 is not limited to the above example. For example, a configuration in which the width W2 is smaller than the width W1, or a configuration in which the width W2 and the width W1 are equivalent is also assumed.

DESCRIPTION OF SYMBOLS 10... Ball joint, 11... Joint mechanism, 12... Dust cover, 20... Ball stud, 21... Shaft part, 22... Spherical part, 23... Flange part, 30... Socket, 31... Housing part, 32... Bottom plate, 33 ...Bearing part, 34...Bearing surface, 40...Knuckle, 51...Fixed part, 52...Seal part, 53...Body part, 54...Connection part, 61...Tightening member, 62...Tightening member, 100...Ball joint , 521...Lip part, 531...First part, 532...Second part, 533...Third part, 541...First step part, 542...Second step part, C...Central axis, E1...Periphery, F1...th 1 base surface, F2...second base surface, S1...first step surface, S2...second step surface.

Claims (4)

Elasticity used in a ball joint comprising a ball stud including a shaft portion on which a flange is formed and a spherical portion installed at one end of the shaft portion, and a socket including a bearing portion that supports the spherical portion. A deformable dust cover,
a fixed part fixed to the socket;
a seal portion having an inner circumferential surface that contacts an outer circumferential surface of the shaft portion;
a body portion located between the fixed portion and the seal portion;
A connecting portion located between the body portion and the seal portion is integrally formed,
The body portion is
a first portion continuous to the fixed portion;
a second portion located between the first portion and the connecting portion;
a third portion located between the first portion and the second portion and protruding toward the ball stud side with respect to the first portion and the second portion;
The inner circumferential surface of the connecting portion is
a first step surface that faces the outer peripheral surface of the flange ; and a first base surface that intersects with the first step surface on the body side of the first step surface and is located outside of the first step surface. an annular first step portion including;
a second step surface that protrudes from the first base surface toward the body section ; and a second step surface that intersects with the second step surface on the body side of the second step surface and is located outside of the second step surface . an annular second step portion including two base surfaces ;
In the process of swinging of the ball stud, the second base surface presses the inner circumferential surface of the third portion toward the spherical portion.
dust cover. The outer circumferential surface of the connecting portion is an inclined surface in which the circumferential edge on the sealing portion side has a smaller diameter than the circumferential edge on the body portion side,
The dust cover according to claim 1, wherein the second base surface is a plane perpendicular to the central axis of the dust cover, or an inclined surface that is closer to the spherical portion at a position closer to the second stepped surface. The dust according to claim 1 or 2, wherein the thickness of the connecting portion in the direction of the central axis of the dust cover increases continuously from the peripheral edge of the connecting portion on the body side to the second stepped surface. cover. A ball joint comprising a joint mechanism and a dust cover,
The joint mechanism is
A ball stud including a shaft portion on which a flange is formed and a spherical portion installed at one end of the shaft portion;
a socket including a bearing part that supports the spherical part,
The dust cover is
a fixed part fixed to the socket;
a seal portion having an inner circumferential surface that contacts an outer circumferential surface of the shaft portion;
a body portion located between the fixed portion and the seal portion;
A connecting portion located between the body portion and the seal portion is integrally formed,
The body portion is
a first portion continuous to the fixed portion;
a second portion located between the first portion and the connecting portion;
a third portion located between the first portion and the second portion and protruding toward the ball stud side with respect to the first portion and the second portion;
The inner circumferential surface of the connecting portion is
a first stepped surface facing the outer circumferential surface of the flange ; and a first base surface located on the outside of the first stepped surface and intersecting the first stepped surface on the body side of the first stepped surface. an annular first step portion including;
a second step surface that protrudes from the first base surface toward the body ; and a second step surface that intersects with the second step surface on the body side of the second step surface and is located outside of the second step surface . an annular second step portion including two base surfaces ;
In the process of swinging of the ball stud, the second base surface presses the inner circumferential surface of the third portion toward the spherical portion.
ball joint.

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