Dust cover and sealing structure

Abstract

This dust cover includes an elastic body having an annular first end section. The first end section includes: an annular end surface; an annular first protrusion that protrudes from the end surface; and an annular second protrusion that protrudes from the end surface more on the radial-direction outer side of the end surface than the first protrusion. In plan view, the apex of the first protrusion is closer to the outer circumferential edge than to the inner circumferential edge of the first protrusion.

Description

Dust cover and sealing structure

[0001] The present invention relates to a dust cover and sealing structure.

[0002] For example, dust covers for protecting ball joints have been proposed in the past. For example, Patent Document 1 discloses a configuration in which the end of the dust cover is fixed to a socket and two annular bead seals are formed on the end surface of the dust cover.

[0003] Japanese Patent Application Laid-Open No. 2008-232249

[0004] Dust covers are required to have high sealing performance to prevent the intrusion of water sprayed at high pressure. In consideration of the above circumstances, one aspect of the present disclosure aims to provide a dust cover that can highly effectively prevent the intrusion of liquid or dust.

[0005] In order to solve the above problems, a dust cover according to one aspect of the present disclosure is a dust cover having an elastic body including a first annular end portion, the first end portion including a annular end face, a first annular protrusion protruding from the end face, and a second annular protrusion protruding from the end face radially outward of the first protrusion, and the top of the first protrusion is closer to the outer peripheral edge than the inner peripheral edge of the first protrusion in a planar view.

[0006] A sealing structure according to one aspect of the present disclosure is a sealing structure comprising a support member including an annular support surface and an outer peripheral surface protruding from the support surface, and a dust cover attached to the support member, wherein the dust cover includes an elastic body including an annular first end portion attached to the support member, the first end portion including an annular end face facing the support surface, an annular first protrusion protruding from the end face, and an annular second protrusion protruding from the end face radially outward of the first protrusion, and the apex of the first protrusion is closer to the outer peripheral edge than the inner peripheral edge of the first protrusion in a planar view.

[0007] FIG. 1 is a cross-sectional view of a ball joint according to an embodiment; FIG. 2 is a cross-sectional view enlarging the vicinity of a first end; FIG. 3 is a plan view of the first end; FIG. 4 is a cross-sectional view enlarging a first protrusion; FIG. 5 is a cross-sectional view enlarging a second protrusion; FIG. 6 is a cross-sectional view enlarging a third protrusion; FIG. 7 is a cross-sectional view of a first protrusion in a modified example; FIG. 8 is a cross-sectional view of a second protrusion in a modified example; FIG. 9 is a cross-sectional view of a third protrusion in a modified example.

[0008] The embodiments for carrying out the present disclosure will be described with reference to the drawings. Note that the dimensions and scale of each element in each drawing may differ from those of the actual product. Furthermore, the embodiment described below is an exemplary embodiment that may be envisioned when carrying out the present disclosure. Therefore, the scope of the present disclosure is not limited to the embodiment exemplified below.

[0009] A: Embodiment Fig. 1 is a cross-sectional view illustrating the configuration of a ball joint 100 according to one embodiment of the present disclosure. The ball joint 100 of this embodiment is used in various devices, such as a suspension system or steering system of an automobile. As illustrated in Fig. 1, the ball joint 100 includes a joint mechanism 10 and a dust cover 20.

[0010] In the following description, the central axis C of the ball joint 100 is assumed, and the direction along the central axis C is referred to as the axial direction Z. The axial direction Z is divided into axial direction Z1 and axial direction Z2. The axial direction Z1 is one direction along the central axis C, and the axial direction Z2 is the direction opposite to the axial direction Z1. Furthermore, the direction along the circumference of an imaginary circle of any diameter centered on the central axis C is referred to as the circumferential direction, and the direction of the radius of the imaginary circle is referred to as the "radial direction." In the radial direction, the direction toward the central axis C is referred to as the "inside," and the direction away from the central axis C is referred to as the "outside." Furthermore, observing an arbitrary element along the line of sight in the axial direction Z is referred to as a "planar view."

[0011] As illustrated in FIG. 1 , the joint mechanism 10 includes a stud 12, a knuckle 13, and a socket 14. The stud 12 is a rod-shaped structure (ball stud) including a spherical portion 121 and an attachment portion 122. The spherical portion 121 is a spherical portion that forms the tip of the stud 12. The attachment portion 122 is a cylindrical portion that is formed with a larger diameter than other portions of the stud 12. The knuckle 13 is fixed to the stud 12. The attachment portion 122 is located between the spherical portion 121 and the knuckle 13.

[0012] The socket 14 is a structure that supports the stud 12. Specifically, the socket 14 includes a bearing portion 15 and a support member 16. A concave spherical bearing surface 151 is formed in the bearing portion 15. The stud 12 is supported by the bearing portion 15 with the surface of the spherical portion 121 in contact with the bearing surface 151. A lubricant is filled in the gap between the surface of the spherical portion 121 and the bearing surface 151. Therefore, the stud 12 is supported by the bearing portion 15 in a state where it can rotate and swing. The support member 16 is a cylindrical structure that surrounds and supports the bearing portion 15. The central axis C is also expressed as the central axis of the socket 14 (bearing portion 15 or support member 16).

[0013] The dust cover 20 is a cover for protecting the joint mechanism 10. Specifically, the dust cover 20 is attached to the joint mechanism 10 to prevent moisture or dust from adhering to the connecting portion between the spherical portion 121 and the bearing portion 15 and to prevent the lubricant applied to the connecting portion from leaking out. As can be understood from the above description, the joint mechanism 10 and the dust cover 20 form a sealed structure that seals the connecting portion between the spherical portion 121 and the bearing portion 15.

[0014] The dust cover 20 includes a first reinforcing ring 21, a second reinforcing ring 22, and an elastic body 23. The elastic body 23 is a generally cylindrical member made of an elastic material. The elastic body 23 is disposed so as to surround the stud 12. Examples of materials for the elastic body 23 include various rubber materials such as chloroprene rubber (CR), silicone rubber (SR), acrylic rubber (ACM), urethane rubber (U), polyurethane rubber (PUR), vinyl methyl silicone rubber (VMQ), ethylene propylene diene rubber (EPDM), and fluororubber (FKM). The central axis C is also referred to as the central axis of the dust cover 20.

[0015] As illustrated in FIG. 1 , the elastic body 23 of this embodiment is a cylindrical elastic membrane integrally formed with a first end 231, a second end 232, and a body portion 233. The first end 231 is an annular portion constituting the end of the elastic body 23 in the axial direction Z1. The first end 231 is fixed to the support member 16. On the other hand, the second end 232 is an annular portion constituting the end of the elastic body 23 in the axial direction Z2. The second end 232 is fixed to the mounting portion 122 of the stud 12. The body portion 233 is a portion located between the first end 231 and the second end 232. The body portion 233 elastically deforms in conjunction with the swinging of the stud 12 relative to the socket 14. As described above, the dust cover 20 is attached to the mounting portion 122 of the stud 12 and the support member 16 of the socket 14.

[0016] The first reinforcing ring 21 and the second reinforcing ring 22 are annular structures having higher rigidity than the elastic body 23. The first reinforcing ring 21 is embedded in a first end 231 of the elastic body 23. The first reinforcing ring 21 reinforces the mechanical strength of the first end 231 and the fixation of the first end 231 to the support member 16. The second reinforcing ring 22 is embedded in a second end 232 of the elastic body 23. The second reinforcing ring 22 reinforces the mechanical strength of the second end 232 and the fixation of the second end 232 to the mounting portion 122.

[0017] The first reinforcing ring 21 and the second reinforcing ring 22 are formed, for example, from a metal material. Examples of metal materials used for the first reinforcing ring 21 and the second reinforcing ring 22 include stainless steel, SPCC (Steel Plate Cold Commercial), and SPHC (Steel Plate Hot Commercial). The first reinforcing ring 21 and the second reinforcing ring 22 may also be formed, for example, from a high-rigidity resin material. The dust cover 20 exemplified above is integrally formed by insert molding using the first reinforcing ring 21 and the second reinforcing ring 22 as insert parts. That is, the dust cover 20 is a molded product in which the first reinforcing ring 21, the second reinforcing ring 22, and the elastic body 23 are integrally formed.

[0018] Fig. 2 is an enlarged cross-sectional view of the vicinity of the first end 231 (region α in Fig. 1). Fig. 2 shows the first end 231 in a state where it is not attached to the support member 16. Fig. 2 also shows the outline of the support member 16 by a chain line. Fig. 3 is a plan view of the first end 231 as viewed in the axial direction Z2.

[0019] As illustrated in FIGS. 1 and 2 , a mounting portion 161 is formed at the end of the outer peripheral surface of the support member 16 in the axial direction Z2. The mounting portion 161 is an annular recess that accommodates the first end 231 of the elastic body 23. Specifically, the support member 16 includes a support surface 162 and an outer peripheral surface 163. The support surface 162 is an annular flat surface facing the axial direction Z2. The outer peripheral surface 163 is a cylindrical surface that protrudes from the support surface 162 in the axial direction Z2. In other words, the support surface 162 is an annular region that protrudes radially outward from the outer peripheral surface 163. The mounting portion 161 is an annular space formed by a step formed by the support surface 162 and the outer peripheral surface 163.

[0020] As illustrated in Fig. 2, the first end portion 231 includes an end face 31, an inner peripheral surface 32, and an outer peripheral surface 33. The end face 31 is an annular flat surface facing the axial direction Z1 and faces the support surface 162 of the support member 16. The end face 31 is formed with openings 34 corresponding to support pins used to support the first reinforcing ring 21 during the insert molding process of the dust cover 20. Specifically, as illustrated in Fig. 3, a plurality of openings 34 are formed at intervals in the circumferential direction. The outer peripheral surface 33 of the first end portion 231 is a cylindrical surface that extends along the central axis C.

[0021] 2 and 3, a first protrusion 40 and a second protrusion 50 are coaxially formed on the end surface 31 of the first end portion 231. Each of the first protrusion 40 and the second protrusion 50 is an annular bead that protrudes from the end surface 31 in the axial direction Z1 and is formed integrally with the first end portion 231.

[0022] The second protrusions 50 are located radially outward of the first protrusions 40. Specifically, the second protrusions 50 are formed with a larger diameter than the first protrusions 40 and surround the entire circumference of the first protrusions 40 in a plan view. As illustrated in Fig. 3 , a plurality of openings 34 are formed in the region of the end face 31 between the first protrusions 40 and the second protrusions 50. That is, the first protrusions 40 are located outside the plurality of openings 34, and the second protrusions 50 are located inside the plurality of openings 34.

[0023] 4 is an enlarged cross-sectional view of the first projection 40. As illustrated in FIGS. 2 to 4, the first projection 40 includes an apex 41, an inner circumferential surface 42, and an outer circumferential surface 43. The apex 41 is the tip portion of the first projection 40 that faces the axial direction Z1 (i.e., the portion that includes the ridge line). The apex 41 is formed in a curved shape (specifically, an R-shape) that continuously connects the inner circumferential surface 42 and the outer circumferential surface 43.

[0024] The inner circumferential surface 42 is a surface of revolution that forms the inner circumference of the first protrusion 40. That is, the inner circumferential surface 42 connects the apex 41 and the end face 31 on the radially inner side of the apex 41. Specifically, the inner circumferential surface 42 is an inclined surface that is inclined with respect to the end face 31 on the inner side of the apex 41. The arc-shaped boundary line where the inner circumferential surface 42 and the end face 31 intersect is the inner circumferential edge Ea1 of the first protrusion 40.

[0025] The outer peripheral surface 43 is a surface of revolution that forms the outer periphery of the first projection 40. That is, the outer peripheral surface 43 connects the apex 41 and the end face 31 on the outer side of the apex 41 in the radial direction. Specifically, the outer peripheral surface 43 is an inclined surface that is inclined with respect to the end face 31 on the outer side of the apex 41. The arc-shaped boundary line where the outer peripheral surface 43 and the end face 31 intersect is the outer peripheral edge Ea2 of the first projection 40.

[0026] In a plan view, the apex 41 of the first projection 40 is closer to the outer peripheral edge Ea2 than to the inner peripheral edge Ea1 of the first projection 40. That is, the apex 41 is located radially outward from the midpoint between the inner peripheral edge Ea1 and the outer peripheral edge Ea2. Specifically, as illustrated in FIG. 4 , the radial dimension Wa1 of the inner peripheral surface 42 exceeds the radial dimension Wa2 of the outer peripheral surface 43 (Wa1 > Wa2). Therefore, the angle Ga1 of the inner peripheral surface 42 relative to the end face 31 is less than the angle Ga2 of the outer peripheral surface 43 relative to the end face 31 (Ga1 < Ga2). As described above, the cross-sectional shape of the first projection 40 is a substantially triangular shape with the apex 41 located radially outward.

[0027] 5 is an enlarged cross-sectional view of the second projection 50. As illustrated in FIGS. 2 and 5, the second projection 50 includes an apex 51, an inner circumferential surface 52, and an outer circumferential surface 53. The apex 51 is the tip portion of the second projection 50 that faces the axial direction Z1 (i.e., the portion that includes the ridge line). The apex 51 is formed in a curved shape (specifically, an R-shape) that continuously connects the inner circumferential surface 52 and the outer circumferential surface 53.

[0028] The inner circumferential surface 52 is a surface of revolution that forms the inner circumference of the second projection 50. That is, the inner circumferential surface 52 connects the apex 51 and the end face 31 on the radially inner side of the apex 51. Specifically, the inner circumferential surface 52 is an inclined surface that is inclined with respect to the end face 31 on the inner side of the apex 51. The arc-shaped boundary line where the inner circumferential surface 52 and the end face 31 intersect is the inner circumferential edge Eb1 of the second projection 50.

[0029] The outer peripheral surface 53 is a surface of revolution that forms the outer periphery of the second projection 50. That is, the outer peripheral surface 53 connects the apex 51 and the end face 31 on the radially outer side of the apex 51. Specifically, the outer peripheral surface 53 is an extension of the outer peripheral surface 33 of the first end portion 231. That is, the outer peripheral surface 33 of the first end portion 231 and the outer peripheral surface 53 of the second projection 50 are located within a common arc surface. The boundary between the outer peripheral surface 53 and the end face 31 is the outer peripheral edge Eb2 of the second projection 50.

[0030] In a plan view, the apex 51 of the second projection 50 is closer to the outer peripheral edge Eb2 than to the inner peripheral edge Eb1 of the second projection 50. That is, the apex 51 is located radially outward from the midpoint between the inner peripheral edge Eb1 and the outer peripheral edge Eb2. Specifically, as illustrated in FIG. 5 , the radial dimension Wb1 of the inner peripheral surface 52 is greater than the radial dimension Wb2 of the outer peripheral surface 53 (Wb1 > Wb2). Furthermore, while the outer peripheral surface 53 is perpendicular to the end face 31 (Gb2 = 90°), the inner peripheral surface 52 is inclined relative to the end face 31 at an angle Gb1 that is less than the angle Gb2 of the outer peripheral surface 53 relative to the end face 31 (Gb1 < Gb2). As described above, the cross-sectional shape of the second projection 50 is generally triangular, with the apex 51 located radially outward.

[0031] The width Wa of the first protrusion 40 is greater than the width Wb of the second protrusion 50 (Wa > Wb). The width Wa of the first protrusion 40 is the distance between the inner peripheral edge Ea1 and the outer peripheral edge Ea2 in the radial direction. The width Wb of the second protrusion 50 is the distance between the inner peripheral edge Eb1 and the outer peripheral edge Eb2 in the radial direction. The width Wa and the width Wb are set to, for example, 0.4 mm or more.

[0032] The height Ha of the first protrusions 40 and the height Hb of the second protrusions 50 are equal (Ha = Hb). The height Ha of the first protrusions 40 is the distance between the end face 31 and the tip of the apex 41. The height Hb of the second protrusions 50 is the distance between the end face 31 and the tip of the apex 51. The heights Ha and Hb are set to dimensions of, for example, 0.1 mm or more. As described above, the width Wa of the first protrusions 40 exceeds the height Ha of the first protrusions 40 (Wa > Ha), and the width Wb of the second protrusions 50 exceeds the height Hb of the second protrusions 50 (Wb > Hb).

[0033] As described above, in this embodiment, the first protrusion 40 and the second protrusion 50 are provided on the end surface 31 of the first end 231, which more effectively prevents liquid or dust sprayed from the outside from entering the dust cover 20 than an embodiment in which only one annular protrusion is formed on the end surface 31 of the first end 231 (hereinafter referred to as the “comparative example”). For example, the first protrusion 40 acts to reduce the flow rate of fluid sprayed from the outside, and the second protrusion 50 acts to block fluid that has entered the gap between the end surface 31 and the support surface 162.

[0034] In the comparative example, a portion of the first end 231 that is spaced apart from one of the protrusions on the end face 31 may be excessively deformed so as to approach the support surface 162. In contrast to the comparative example, in the present embodiment, the posture of the first end 231 is stably supported by the first protrusion 40 and the second protrusion 50 that are spaced apart from each other in the radial direction. Therefore, compared to the comparative example, there is an advantage in that excessive deformation of the first end 231 can be suppressed.

[0035] Furthermore, in this embodiment, the apex 41 of the first protrusion 40 is closer to the outer peripheral edge Ea2 than to the inner peripheral edge Ea1 of the first protrusion 40. Therefore, in the annular region of the support surface 162 that contacts the first protrusion 40, the contact pressure acting from the first protrusion 40 on the radially outer portion exceeds the contact pressure acting on the radially inner portion. As a result of the above-described uneven distribution of the contact pressure from the first protrusion 40, the first protrusion 40 can more effectively prevent liquid or dust from entering inward through the gap between the end face 31 of the first end 231 and the support surface 162 of the support member 16, compared to, for example, a configuration in which the cross section of the first protrusion 40 is simply semicircular.

[0036] In particular, in this embodiment, the apex 51 of the second protrusion 50 is closer to the outer peripheral edge Eb2 than to the inner peripheral edge Eb1 of the second protrusion 50. Therefore, in the annular region of the support surface 162 that contacts the second protrusion 50, the contact pressure acting from the second protrusion 50 on the radially outer portion exceeds the contact pressure acting on the radially inner portion. As a result of the above-described uneven distribution of the contact pressure from the second protrusion 50, the second protrusion 50 can more effectively prevent liquid or dust from entering inward through the gap between the end face 31 of the second end 232 and the support surface 162 of the support member 16, compared to, for example, a configuration in which the cross section of the second protrusion 50 is simply semicircular.

[0037] 2, the inner circumferential surface 32 of the first end portion 231 is a tapered surface of revolution (specifically, a truncated cone surface) that expands in diameter toward the end face 31. Specifically, the inner diameter D1 of the inner circumferential surface 32 at the end portion in the axial direction Z1 is greater than the inner diameter D2 of the inner circumferential surface 32 at the opposite end portion (i.e., the end portion in the axial direction Z2) (D1 > D2). In other words, the inner circumferential surface 32 is inclined with respect to the axial direction Z. The inner circumferential surface 32 contacts the outer circumferential surface 163 of the support member 16.

[0038] 2 , the first reinforcing ring 21 includes an engagement end 211. The engagement end 211 is a blade-like portion that is exposed from the inner circumferential surface 32 of the first end 231 when the first end 231 is attached to the support member 16. The engagement end 211 bites into the outer circumferential surface 163 of the support member 16, thereby firmly fixing the first end 231 to the support member 16.

[0039] A third protrusion 60 is formed on the inner circumferential surface 32. The third protrusion 60 is an annular protrusion that protrudes radially inward from the inner circumferential surface 32 and is formed integrally with the first end portion 231. The third protrusion 60 is located in the axial direction Z1 of the inner circumferential surface 32. That is, the third protrusion 60 protrudes radially inward from the inner circumferential surface 32 at a position closer to the end face 31 than the inner circumferential surface 32. Specifically, the third protrusion 60 is located between the end face 31 and the engagement end 211 in the axial direction Z. As described above, the third protrusion 60 is located between the inner circumferential surface 32 and the end face 31 of the first end portion 231.

[0040] 6 is an enlarged cross-sectional view of the third projection 60. As illustrated in FIGS. 2 and 6, the third projection 60 includes an apex 61, a first side surface 62, and a second side surface 63. The apex 61 is the tip portion of the third projection 60 (i.e., the portion including the ridge line). The apex 61 is formed in a curved shape (specifically, an R-shape) that continuously connects the first side surface 62 and the second side surface 63.

[0041] The first side surface 62 is a cylindrical surface of revolution that intersects with the inner circumferential surface 32 in the axial direction Z1 of the inner circumferential surface 32. The first side surface 62 faces the outer circumferential surface 163 of the support member 16. The inner circumferential surface 32 and the first side surface 62 may be expressed as constituting the inner circumferential surface of the first end portion 231. The second side surface 63 is an annular flat surface facing the axial direction Z1. Specifically, the second side surface 63 is an extension of the end surface 31 of the first end portion 231. That is, the end surface 31 of the first end portion 231 and the second side surface 63 of the third protrusion 60 are located in a common plane perpendicular to the axial direction Z. The dimension Hc1 of the first side surface 62 in the axial direction Z exceeds the dimension Hc2 of the second side surface 63 in the radial direction (Hc1 > Hc2). The dimension Hc2 of the second side surface 63 is, for example, 0.1 mm or greater.

[0042] The inner diameter of the third projection 60 is smaller than the outer diameter of the outer peripheral surface 163 of the support member 16. Therefore, the first side surface 62 of the third projection 60 contacts the outer peripheral surface 163 of the support member 16 with a predetermined interference. Similarly, the inner peripheral surface 32 of the first end 231 contacts the outer peripheral surface 163 of the support member 16 with a predetermined interference. As described above, the inner peripheral surface 32 expands in diameter in the axial direction Z1, and therefore the interference at the end of the inner peripheral surface 32 in the axial direction Z2 exceeds the interference at the end of the inner peripheral surface 32 in the axial direction Z1. In other words, the closer the portion of the inner circumferential surface 32 is to the body portion 233, the higher the contact pressure with the outer peripheral surface 163 of the support member 16.

[0043] As described above, in this embodiment, the third protrusion 60 is formed to protrude from the inner circumferential surface 32 of the first end portion 231. Therefore, the third protrusion 60 can effectively prevent the intrusion of liquid or dust that has passed through the first protrusion 40 and the second protrusion 50. Specifically, the third protrusion 60 blocks moisture or dust from passing through the gap between the inner circumferential surface 32 of the first end portion 231 and the outer circumferential surface 163 of the support member 16 in the axial direction Z2.

[0044] In particular, in this embodiment, the third protrusion 60 is located between the end face 31 and the engagement end 211 in the axial direction Z. Therefore, compared to, for example, a configuration in which the third protrusion 60 is formed in the axial direction Z2 of the engagement end 211, the third protrusion 60 can more effectively prevent the intrusion of liquid or dust.

[0045] B: Modifications Specific modifications that can be added to the above-mentioned embodiments are exemplified below. Two or more embodiments arbitrarily selected from the following examples may be combined as appropriate within the scope of not mutually contradicting each other.

[0046] (1) The shape of the first protrusion 40 may be modified as appropriate. For example, as illustrated in Fig. 7, the outer peripheral surface 43 may be perpendicular to the end face 31 of the first end portion 231 (Ga2 = 90°). Similarly, the shape of the second protrusion 50 may be modified as appropriate. For example, as illustrated in Fig. 8, the outer peripheral surface 53 of the second protrusion 50 may be an inclined surface inclined at an angle Gb2 (Gb2 < 90°) with respect to the end face 31 of the first end portion 231.

[0047] (2) In the above-described embodiment, the outer peripheral surface 53 of the second protrusion 50 is an extension of the outer peripheral surface 33 of the first end portion 231. However, as shown in FIG. 9, the outer peripheral surface 53 of the second protrusion 50 may be positioned radially inward from the outer peripheral surface 33 of the first end portion 231.

[0048] In addition, according to the configuration in which the outer peripheral surface 53 of the second protrusion 50 is an extension surface from the outer peripheral surface 33 of the first end portion 231 as illustrated in Figure 2, compared to the configuration in Figure 9 in which the second protrusion 50 is located inside the outer peripheral surface 53, there is an advantage in that it is possible to effectively prevent liquid or dust from entering the gap between the end surface 31 of the first end portion 231 and the support surface 162 of the support member 16.

[0049] (3) In the above-described embodiment, the inner circumferential surface 32 of the first end portion 231 is a surface of revolution that expands in diameter in the axial direction Z1, and the first side surface 62 of the third protrusion 60 is a cylindrical surface of revolution. However, the angular relationship between the inner circumferential surface 32 and the first side surface 62 is not limited to the above example. For example, as illustrated in FIG. 10 , a configuration is also conceivable in which the inner circumferential surface 32 of the first end portion 231 is a cylindrical surface of revolution, and the first side surface 62 of the third protrusion 60 is a tapered surface of revolution that contracts in diameter toward the end surface 31. Note that the third protrusion 60 may be omitted. That is, the inner circumferential surface 32 may extend to the end surface 31.

[0050] (4) In the above embodiment, the width Wa of the first projection 40 is greater than the width Wb of the second projection 50 (Wa > Wb), but the width Wa and the width Wb may be equal (Wa = Wb) or may be less than the width Wb (Wa < Wb). In addition, the height Ha of the first projection 40 and the height Hb of the second projection 50 may be different.

[0051] (5) In the above-described embodiment, the dust cover 20 includes the first reinforcing ring 21 and the second reinforcing ring 22. However, one or both of the first reinforcing ring 21 and the second reinforcing ring 22 may be omitted. In a configuration in which the first reinforcing ring 21 is omitted, the first end 231 may be fastened to the support member 16 by an annular fastening member such as a circlip or a band. Similarly, in a configuration in which the second reinforcing ring 22 is omitted, the second end 232 may be fastened to the mounting portion 122 by an annular fastening member such as a circlip or a band.

[0052] (6) One or more of the configurations exemplified in the above-described embodiments may be omitted as desired. For example, the above-described embodiments include the following configurations: [Configuration 1] a configuration in which the top 41 of the first projection 40 is closer to the outer peripheral edge Ea2 of the first projection 40 than to the inner peripheral edge Ea1 of the first projection 40 in a plan view; and [Configuration 2] a configuration in which the top 51 of the second projection 50 is closer to the outer peripheral edge Eb2 of the second projection 50 than to the inner peripheral edge Eb1 of the second projection 50 in a plan view. However, one or both of Configurations 1 and 2 may be omitted.

[0053] For example, examples of forms in which configuration 1 is omitted include a configuration in which the top 41 of the first protrusion 40 is closer to the inner peripheral edge Ea1 than to the outer peripheral edge Ea2 of the first protrusion 40 in a planar view, or a configuration in which the top 41 of the first protrusion 40 is equidistant from the inner peripheral edge Ea1 and the outer peripheral edge Ea2 of the first protrusion 40 in a planar view.

[0054] Furthermore, examples of configurations in which configuration 2 is omitted include a configuration in which the top 51 of the second protrusion 50 is closer to the inner peripheral edge Eb1 than to the outer peripheral edge Eb2 of the second protrusion 50 in a planar view, or a configuration in which the top 51 of the second protrusion 50 is equidistant from the inner peripheral edge Eb1 and the outer peripheral edge Eb2 of the second protrusion 50 in a planar view.

[0055] (7) The term "nth" (n is a natural number) in this application is used only as a formal and convenient label to distinguish each element in the description and does not have any substantive meaning. Therefore, there is no room for restrictive interpretation of the position of each element or the order of manufacture, etc., based on the term "nth."

[0056] C: Supplementary Notes From the above-described exemplary embodiments, the following configurations can be understood, for example.

[0057] A dust cover according to one aspect (Aspect 1) of the present disclosure is a dust cover comprising an elastic body including an annular first end portion, the first end portion including an annular end surface, a first annular protrusion protruding from the end surface, and a second annular protrusion protruding from the end surface radially outward of the first protrusion, the apex of the first protrusion being closer to the outer periphery than the inner periphery of the first protrusion in a plan view. According to this aspect, the first and second protrusions are provided on the end surface of the first end portion, which can more effectively prevent liquid or dust from entering the dust cover than a configuration in which only a single annular protrusion is formed on the end surface of the first end portion. Furthermore, the apex of the first protrusion is closer to the outer periphery than the inner periphery of the first protrusion. Therefore, compared to, for example, a configuration in which the top of the first protrusion is closer to the inner peripheral edge than the outer peripheral edge of the first protrusion, or a configuration in which the top of the first protrusion is equidistant from the inner and outer peripheral edges of the first protrusion (for example, a configuration in which the cross section of the first protrusion is a simple semicircle), the first protrusion can effectively prevent liquid or dust from entering inward through the gap between the end face of the first end and the support surface to which the first end is attached.

[0058] In a specific example (Aspect 2) of Aspect 1, the apex of the second protrusion is closer to the outer peripheral edge of the second protrusion than to the inner peripheral edge of the second protrusion in a planar view. In the above aspect, the apex of the second protrusion is closer to the outer peripheral edge of the second protrusion than to the inner peripheral edge of the second protrusion. Therefore, compared to a configuration in which the apex of the second protrusion is closer to the inner peripheral edge of the second protrusion than to the outer peripheral edge of the second protrusion, or a configuration in which the apex of the second protrusion is equidistant from the inner and outer peripheral edges of the second protrusion (for example, a configuration in which the cross section of the second protrusion is simply semicircular), the second protrusion can more effectively prevent liquid or dust from entering inward through the gap between the end face of the first end and the support surface to which the first end is attached.

[0059] In a specific example (Aspect 3) of Aspect 1 or Aspect 2, the outer peripheral surface of the second protrusion is an extension of the outer peripheral surface of the first end. According to the above aspect, since the outer peripheral surface of the second protrusion is an extension of the outer peripheral surface of the first end, it is possible to more effectively prevent liquid or dust from entering the gap between the end face of the first end and the support surface to which the first end is attached, compared to, for example, an embodiment in which the second protrusion is located radially inward from the outer peripheral surface of the first end. Note that a configuration in which the outer peripheral surface of the second protrusion is an extension of the outer peripheral surface of the first end means, for example, a configuration in which the outer peripheral surface of the first end and the outer peripheral surface of the second protrusion form a single surface of revolution, i.e., a configuration in which there is no step between the outer peripheral surface of the first end and the outer peripheral surface of the second protrusion.

[0060] In a specific example (Aspect 4) of any of Aspects 1 to 3, the first end further includes an inner circumferential surface that expands in diameter toward the end face, and an annular third protrusion that protrudes radially inward from the inner circumferential surface at a position closer to the end face than the inner circumferential surface. In the above aspects, the third protrusion protrudes from the inner circumferential surface of the first end. Therefore, the third protrusion can effectively prevent the intrusion of liquid or dust that has passed through the first and second protrusions.

[0061] In a specific example (Aspect 5) of Aspect 4, the valve further includes a reinforcing ring embedded in the first end portion, the reinforcing ring including an annular engagement end exposed from the inner circumferential surface of the first end portion, and the third protrusion is located axially between the end surface and the engagement end. In the above aspect, the third protrusion is located axially between the end surface and the engagement end. Therefore, the third protrusion can effectively prevent the intrusion of liquid or dust.

[0062] A sealing structure according to one aspect (aspect 6) of the present disclosure is a sealing structure comprising a support member including an annular support surface and an outer peripheral surface protruding from the support surface, and a dust cover attached to the support member, wherein the dust cover includes an elastic body including an annular first end portion attached to the support member, the first end portion including an annular end face facing the support surface, an annular first protrusion protruding from the end face, and an annular second protrusion protruding from the end face radially outward of the first protrusion, and the apex of the first protrusion is closer to the outer peripheral edge than the inner peripheral edge of the first protrusion in a planar view.

[0063] 100...ball joint, 10...joint mechanism, 12...stud, 13...knuckle, 14...socket, 15...bearing portion, 16...support member, 20...dust cover, 21...first reinforcing ring, 211...engagement end, 22...second reinforcing ring, 23...elastic body, 31...end surface, 32...inner peripheral surface, 33...outer peripheral surface, 34...opening, 40...first protrusion, 41...top portion, 42...inner peripheral surface, 43...outer peripheral surface, 50...second protrusion, 51...top, 52...inner peripheral surface, 53...outer peripheral surface, 60...third protrusion, 61...top, 62...first side surface, 63...second side surface, 121...spherical portion, 122...mounting portion, 151...bearing surface, 161...mounting portion, 162...support surface, 163...outer peripheral surface, 231...first end, 232...second end, 233...body portion.

Claims

1. A dust cover comprising an elastic body including an annular first end portion, the first end portion including an annular end face, a first annular protrusion protruding from the end face, and a second annular protrusion protruding from the end face radially outward of the first protrusion, the apex of the first protrusion being closer to the outer circumferential edge of the first protrusion than to the inner circumferential edge of the first protrusion in a plan view.

2. The dust cover according to claim 1, wherein the top of the second protrusion is closer to the outer circumferential edge than to the inner circumferential edge of the second protrusion in a plan view.

3. The dust cover according to claim 2, wherein the outer circumferential surface of the second protrusion is an extension of the outer circumferential surface of the first end portion.

4. A dust cover as claimed in claim 1, wherein the first end further includes an inner circumferential surface that expands in diameter towards the end face, and a third annular projection that protrudes radially inward from the inner circumferential surface at a position closer to the end face than the inner circumferential surface.

5. The dust cover of claim 4, further comprising a reinforcing ring embedded in the first end portion, the reinforcing ring including an annular engaging end exposed from the inner circumferential surface of the first end portion, and the third protrusion being located between the end surface and the engaging end in the axial direction.

6. A sealing structure comprising: a support member including an annular support surface and an outer peripheral surface protruding from the support surface; and a dust cover attached to the support member, wherein the dust cover includes an elastic body including an annular first end portion attached to the support member, the first end portion including an annular end face facing the support surface, a first annular protrusion protruding from the end face, and a second annular protrusion protruding from the end face radially outward of the first protrusion, and wherein the apex of the first protrusion is closer to the outer peripheral edge than the inner peripheral edge of the first protrusion in a plan view.

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