Ball joint

Abstract

To reduce a mold width of a housing mold for insert molding of a ball joint.SOLUTION: A ball joint J1 includes: a ball stud 10 formed by integrally joining a ball part 10b to the other end part of a stud part 10s connected at one end part with a structure; and a resin housing 21 which has an inner spherical surface 21a including the ball part 10b through a ball seat 30 and has an opening space from which the stud part 10s joined to the ball part 10b protrudes. The housing 21 includes: a body part 21b having the inner spherical surface 21a; a flange part 21d protruding in an annular form on an outer peripheral surface of the body part 21b; a dome part 21g protruding in a semi-spherical form below the flange part 21d; and a bar grip part 21j having a connection part 21h connected to the flange part 21d.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a ball joint that plays a role in reducing shocks from road surfaces in a vehicle. [Background technology]

[0002] A vehicle's suspension reduces the shock transmitted from the road surface to the vehicle body, while the stabilizer increases the vehicle body's roll rigidity (rigidity against twisting). The suspension and stabilizer are connected via a stabilizer link. The stabilizer link is made up of a rod-shaped support bar with ball joints on both ends.

[0003] An example of this type of ball joint is ball joint J, the cross section of which is shown in Figure 18. This ball joint J is configured such that ball portion 10b of metal ball stud 10 is rotatably housed (encompassed) in a resin cup-shaped housing 11, with ball seat 30 interposed therebetween.

[0004] The housing 11 includes a body portion 11b having an inner spherical surface 11a of a spherical curved shape that encompasses the ball portion 10b up to the position of the opening 11c. The inner spherical surface 11a is also referred to as the housing inner spherical surface 11a. The outer peripheral surface of the body portion 11b forms a roughly spherical shape that conforms to the housing inner spherical surface 11a. In addition, the outer peripheral surface of the body portion 11b includes upper and lower flange portions 11g and 11k that go around in an annular shape both above and below a horizontal line H that imaginarily passes through the center of the ball portion 10b.

[0005] The upper and lower flanges 11g, 11k are parallel to each other and spaced apart from each other, protruding outward, with a circular groove 11j formed between the flanges 11g, 11k. The upper portion of the circumferential upper end 11f of the housing 11 forms a protrusion 11f2 that protrudes outward in a circular shape parallel to the horizontal line H. A circular groove 11i is formed between this protrusion 11f2 and the upper flange 11g.

[0006] Housing 11 is insert molded by pouring resin into a housing mold (not shown) so as to cover ball portion 10b via ball seat 30, and also so as to integrally bond the outer peripheral surface of housing 11 with the tip of a support bar (see support bar 100 in FIG. 2) disposed along horizontal line H. When support bar 100 is horizontal along horizontal line H, the axis of ball stud 10 is configured to be perpendicular to horizontal line H (also called equator H) as indicated by vertical line V.

[0007] In the insert molding, first, the ball portion 10b is enclosed in a ball seat 30 having a protruding portion 30a that surrounds the upper end side portion. When the enclosed ball portion 10b is set in a housing mold and resin is poured in, a recessed portion 11q that is recessed by the protruding portion 30a is formed in a circumferential shape at a position of the housing inner spherical surface 11a that is a virtual horizontal extension of the upper flange portion 11g of the body portion 11b. In other words, the protruding portion 30a of the ball seat 30 is fitted into the recessed portion 11q of the housing inner spherical surface 11a. In this fitted state, the ball portion 10b is enclosed in the ball seat 30 fixed to the body portion 11b, and the ball joint J is formed.

[0008] The ball stud 10 has a structure in which a spherical ball portion 10b is integrally connected to one end of a rod-shaped stud portion 10s. A male thread 10n is threaded into the stud portion 10s, and a flange portion 10a1 and a small flange portion 10a2 are formed at a distance from each other on the tip side (ball portion 10b side) of the male thread 10n, which extend in a circular shape. A dust cover 13 for dust prevention is disposed between the flange portion 10a1 and the upper end portion 11f of the housing 11. The upper end portion of the dust cover 13 is fixed between the flange portion 10a1 and the small flange portion 10a2, and the lower end portion is fixed to a groove portion 11i of the upper end portion 11f of the housing 11.

[0009] The upper end 11f of the housing 11 has a tapered surface 11f1 that slopes inward from the upper end surface. The angle of inclination of the tapered surface 11f1 is set to satisfy a predetermined pivot angle of the ball stud 10 when the ball stud 10 pivots (arrow α1).

[0010] In such a ball joint J, as the vehicle suspension strokes, the ball portion 10b sways and slides on the housing inner spherical surface 11a via the ball seat 30, and the characteristics of this swaying and sliding are defined as the swaying torque and the rotational torque (also referred to as each torque). When the ball portion 10b rotates, if the frictional force on the housing inner spherical surface 11a increases and each torque increases, the ride quality deteriorates.

[0011] When the interference between the ball portion 10b and the housing inner spherical surface 11a is reduced in the housing 11, each torque can be reduced, but at the same time, the elastic lift amount increases. The elastic lift amount is the amount of movement of the ball portion 10b via the ball seat 30 on the housing inner spherical surface 11a. When the elastic lift amount increases, the ball portion 10b moves significantly in the housing 11, causing play in the ball joint J and leading to abnormal noise while the vehicle is running. In other words, there is a contradictory relationship between each torque and the elastic lift amount, such that when each torque decreases, the elastic lift amount increases. For example, there are ball joints of this type described in Patent Documents 1, 2, and 3. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Patent No. 3168229 [Patent Document 2] Patent No. 3369659 [Patent Document 3] JP 2014-028984 A Summary of the Invention [Problem to be solved by the invention]

[0013] As described above, ball joint J has a double flange structure with flange portions 11g, 11k on the outer periphery of housing 11 that protrude outward in parallel to each other on top and bottom sides of equator H. In this structure, groove portion 11j is present in an annular shape between upper and lower flange portions 11g, 11k. Because of this uneven protruding structure in the direction of equator H, if the housing mold only has a cavity capable of forming housing 11, the housing mold will not be able to be removed once the resin poured into the housing mold has solidified.

[0014] Therefore, the housing mold has a configuration in which it can be divided into two in the vertical direction and has a slide mold that can slide in the left-right direction (opposite directions) along the equator H. If a housing mold having this slide mold is used, the housing mold can be removed by sliding the slide mold along the equator H after the poured resin has solidified.

[0015] However, a housing mold with a sliding configuration requires a width to slide left and right along the equator H. This means that the width of the housing mold becomes large, for example about 300 mm, and as a result, there is an issue that the mold width (or flat area) becomes large. When the housing mold width becomes large, the number of housing molds that can be placed on one base decreases. This reduces the number of ball joints that can be insert molded at one time, and increases equipment costs and production takt time.

[0016] The present invention has been made in view of the above background, and an object of the present invention is to provide a ball joint that enables the width of a housing mold for insert molding the ball joint to be reduced. [Means for solving the problem]

[0017] In order to solve the above-mentioned problems, the ball joint of the present invention is a ball joint comprising: a ball stud having one end connected to a structure and a metallic spherical portion integrally joined to the other end of a stud portion, the other end of which is connected to a structure; and a resin housing having an inner spherical surface which contains the spherical portion up to the position of the opening, and a space which opens so that the stud portion joined to the spherical portion can protrude, the housing comprising a body portion having an inner spherical surface which contains the spherical portion up to the position of the opening, and a ring-shaped body portion which is disposed on the outer circumferential surface of the body portion along a horizontal line which imaginarily passes through the center of the spherical portion, The ball joint has a flange portion that protrudes in a circumferential direction, a dome portion that protrudes hemispherically along the inner spherical surface below the flange portion, and a bar grip portion to which a support bar that is connected to the other ball joint is fixed, and the bar grip portion has a cylindrical shape and comprises a cylindrical portion into which the support bar is inserted, a connection portion that connects the flange portion, the dome portion, and the cylindrical portion along the horizontal line, and at least two stay portions that extend from the cylindrical portion to the flange portion along the upper or lower side of the connection portion. Effect of the Invention

[0018] According to the present invention, the width of the housing mold for insert-molding the ball joint can be reduced. [Brief description of the drawings]

[0019] [Figure 1] 1 is a side view showing a configuration of a ball joint according to an embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view taken along line II-II of FIG. 1. [Diagram 3] FIG. 2 is a perspective view showing the configuration of a ball joint according to the present embodiment, as viewed obliquely from above. [Figure 4] FIG. 2 is a perspective view showing the configuration of the ball joint of the present embodiment, as viewed obliquely from below. [Diagram 5] FIG. 2 is a top perspective view showing the configuration of a ball joint according to the present embodiment. [Figure 6] FIG. 2 is a bottom perspective view showing the configuration of the ball joint of the present embodiment. [Figure 7] 1 is a cross-sectional view showing a configuration of a ball joint not including a ball seat according to an embodiment of the present invention. [Figure 8] FIG. 4 is a side view showing the configuration of a ball joint according to Modification 1 of the present embodiment. [Figure 9] 11 is a perspective view showing the configuration of a ball joint of Modification 1, as viewed obliquely from above. FIG. [Figure 10] 11 is a perspective view showing the configuration of a ball joint of Modification 1, as viewed obliquely from below. FIG. [Figure 11] FIG. 11 is a top perspective view showing the configuration of a ball joint according to Modification 1. [Figure 12] FIG. 11 is a perspective view showing the configuration of a ball joint of Modification 1 as viewed from below. [Figure 13] FIG. 11 is a side view showing the configuration of a ball joint according to Modification 2 of the embodiment. [Figure 14] FIG. 11 is a perspective view showing the configuration of a ball joint of Modification 2, as viewed obliquely from above. [Figure 15] 11 is a perspective view showing the configuration of a ball joint of Modification 2, as viewed obliquely from below. FIG. [Figure 16] FIG. 11 is a perspective view showing the configuration of a ball joint of Modification 2 as viewed from below. [Figure 17] FIG. 11 is a bottom perspective view showing the configuration of a ball joint according to Modification 3 of the present embodiment. [Figure 18] FIG. 1 is a vertical cross-sectional view of a conventional ball joint. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, in all the drawings in this specification, the same reference numerals are used to designate corresponding components, and the description thereof will be omitted as appropriate. <Embodiment> Fig. 1 is a side view showing the configuration of a ball joint according to an embodiment of the present invention, Fig. 2 is a cross-sectional view taken along line II-II shown in Fig. 1.

[0021] However, the stud portion 10s of the ball joint J1 is fixed to the suspension or stabilizer described above. The suspension or stabilizer constitutes a structure described in the claims. In the ball joint J1 shown in Figures 1 and 2, the tip side of the stud portion 10s is the "upper" side, and the dome portion 21g (described later) side of the housing 21 is the "lower" side.

[0022] The ball joint J1 of the embodiment shown in FIG. 1 differs from the conventional ball joint J (FIG. 18) in that the housing 21 has the following shape.

[0023] The housing 21 is made of resin and includes a cup-shaped (see FIG. 2) body 21b that contains the ball portion (spherical portion) 10b of the metal ball stud 10, an annular flange portion 21d that goes around the outer circumferential surface of the body portion 21b, an upper end portion 21f that protrudes cylindrically above the flange portion 21d, and a dome portion 21g that protrudes below the flange portion 21d. The dome portion 21g forms a semispherical surface that protrudes below the flange portion 21d and has a plurality of ribs 21k that extend radially from this semispherical surface. The housing 21 further includes a bar grip portion 21j that is connected to the flange portion 21d via a connecting portion 21h and into which a support bar 100 for connecting a ball joint is inserted.

[0024] However, an axis (vertical line) V that passes perpendicular to a horizontal line H that passes through the center of ball portion 10b coincides with the axis of ball stud 10. Furthermore, horizontal line H coincides with the center of ball portion 10b, the axis of horizontally disposed support bar 100, and an axis (also called the flange axis) that passes radially through the center of the thickness width of flange portion 21d. Horizontal line H is parallel to the axis of support bar 100 and is also called the equator H because it passes horizontally through the center of ball portion 10b.

[0025] The housing 21 is insert molded by pouring resin into a housing mold for forming the body portion 21b, flange portion 21d, upper end portion 21f, dome portion 21g, and bar grip portion 21j. During this insert molding, the ball portion 10b enclosed by the ball seat 30 of the ball stud 10 is assembled with the housing mold along a vertical line V. Furthermore, the tip portion of the support bar 100 is assembled with the housing mold along a horizontal line H, and is insert molded so as to be integrally joined with the housing 21.

[0026] However, the housing type can be separated into upper and lower parts along the horizontal line H of the ball joint J1.

[0027] The ball stud 10 has a high degree of sphericity achieved by integrating the ball portion 10b and the stud portion 10s by resistance welding, enabling smooth movement with low torque. However, if the ball portion 10b can be machined to be spherical, the ball stud 10 may be an integrated ball stud 10 in which the ball portion 10b and the stud portion 10s are made of a single metal material.

[0028] The ball stud 10 has a rod-shaped stud portion 10s and a spherical ball portion 10b integrally connected to one end of the stud portion 10s. A male thread 10n is threaded into the stud portion 10s, and a flange portion 10a1 and a small flange portion 10a2 are formed below the male thread 10n (toward the ball portion 10b) and are spaced apart from each other and extend in a circular manner. A dust cover 13 is disposed between the flange portion 10a1 and the small flange portion 10a and between the upper end portion 21f of the housing 21 and the upper surface of the flange portion 21d.

[0029] 2, the inner spherical surface (housing inner spherical surface) 21a of the housing 21 that contains the spherical ball portion 10b is spherically curved along the spherical shape of the ball portion 10b. The housing inner spherical surface 21a that is molded in close contact with the ball portion 10b tightens the ball portion 10b due to molding shrinkage.

[0030] The body 21b of the housing 21 that contains the ball portion 10b has an outer circumferential surface that conforms to the inner spherical surface, so that the thickness of the portion other than the flange portion 21d is substantially uniform or uniform. In other words, the thickness of the spherical curved shape of the body 21b excluding the flange portion 21d is substantially uniform.

[0031] The frictional force between the housing inner spherical surface 21a and the ball portion 10b is desirably within an appropriate range for realizing a low-torque stabilizer link. In other words, it is desirable that the frictional force be able to reduce the rocking torque and rotational torque (each torque) of the ball stud 10 so as to improve the ride comfort of the vehicle, and to reduce the amount of elastic lift so as to prevent rattling from occurring in the ball joint J1.

[0032] In the body portion 21b of the housing 21 described above, the thickness toward the center of the ball portion 10b is uniform or approximately uniform, so the tightening force of the ball portion 10b is uniform or approximately uniform, making it possible to reduce torque. Furthermore, since the flange portion 21d is single, molding shrinkage that tightens the ball portion 10b is reduced, achieving low torque.

[0033] Here, the suspension of the vehicle reduces the shock transmitted from the road surface to the vehicle body, and the stabilizer increases the roll rigidity of the vehicle body, and the suspension and the stabilizer are connected via a stabilizer link. The stabilizer link is configured by providing the above-mentioned ball joint J1 on both ends of a rod-shaped support bar 100.

[0034] The support bar 100 is made of a metal material such as a steel pipe, and its tip (see FIG. 2) is pressed in the direction in which the ball stud 10 extends to deform it into a flat plate. The support bar 100 may be made of resin or other materials other than metal. Furthermore, if the support bar 100 is made of resin, it may be formed integrally with the housing 21.

[0035] Next, the housing 21 will be described in detail. As shown in Fig. 2, the body 21b of the housing 21 has a wall thickness designed not to be damaged when the ball portion 10b rotates, and the outer peripheral surface of the body 21b is provided with one flange portion 21d (Fig. 1) that protrudes outward and goes around in an annular shape. The cross-sectional shape of the upper end portion 21f above the flange portion 21d is straight on the outer peripheral side and tapered on the inner peripheral side (tapered surface 1f1).

[0036] In other words, the upper end portion 21f of the body portion 21b has a tapered surface 1f1 that slopes from the upper end surface toward the inner circumference, and the inclination angle of this tapered surface 1f1 is an angle that satisfies the predetermined swing angle of the ball stud 10 when the ball stud 10 swings (arrow α1).

[0037] The bar grip portion 21j has a cylindrical shape with its axis extending along the equator H, and is connected to the flange portion 21d and the dome portion 21g of the body portion 21b via a connecting portion 21h. A support bar 100 is inserted and fixed inside the cylindrical bar grip portion 21j with its tip facing the housing 21. The support bar 100 has an elliptical cone shape that slopes upward from the top and bottom crushed tip toward the rear end.

[0038] The connecting portion 21h of the bar grip portion 21j has an upper inclined surface (also called an upper inclined surface) 1h1 along the upper inclination of the elliptical cone shape of the support bar 100, and a lower inclined surface (also called a lower inclined surface) 1h2 along the lower inclination. The tips of the upper and lower inclined surfaces 1h1 and 1h2 are joined to the flange portion 21d. The central axes of this flange portion 21d, the bar grip portion 21j having the connecting portion 21h, and the support bar 100 coincide with the equator H. The upper inclined surface 1h1 constitutes a downward inclined surface as described in the claims.

[0039] The upper inclined surface 1h1 of the connection part 21h is inclined at an angle θ1 with respect to the outer peripheral surface of the bar grip part 21j along the equator H. This inclined surface 1h1 is formed to prevent the dust cover 13 from being pinched between the bar grip part 21j and the ball stud 10 when the ball stud 10 swings and tilts, preventing the ball stud 10 from being unable to swing at the required swing angle (referred to as preventing the stud from swinging). The lower inclined surface 1h2 of the connection part 21h is also inclined at the same angle as the upper inclined surface 1h1. In other words, the outer periphery of the connection part 21h is an elliptical cone-shaped outer periphery.

[0040] As shown in FIG. 3 or 4, stays 1j1 and 1j2 are provided on both sides of the connecting portion 21h in a plan view, each of which has a vertical width and extends in the direction of the equator H. The stays 1j1 and 1j2 (two stays) on both sides have their ends facing the housing 21 connected to both the flange portion 21d and the dome portion 21g, and their rear ends connected to the cylindrical portion of the bar grip portion 21j. The stays 1j1 and 1j2 on both sides are divided into a portion that joins to the upper surface of the flange portion 21d (FIG. 3) and a portion that abuts against the lower surface of the flange portion 21d (FIG. 4) at their tip ends. That is, each stay 1j1 and 1j2 has a double stay structure that extends in parallel to connect the bar grip portion 21j to the flange portion 21d and the dome portion 21g.

[0041] The upper ends of both stays 1j1, 1j2 are inclined along an upper inclined surface 1h1 as shown in Fig. 3, and further have tapered surfaces 1a, 2a that slope downward toward the other stay as shown in Fig. 5. The inclination along the upper inclined surface 1h1 of each stay 1j1, 1j2 and the tapered surfaces 1a, 2a are formed to prevent the stud from becoming unable to swing as described above.

[0042] Returning to Fig. 3, the upper inclined surface 1h1 of the connecting portion 21h of the bar grip portion 21j is provided with a stay 1j3 (also called an upper middle stay 1j3) that extends parallel to the stays 1j1 and 1j2 at the middle of the stays. The upper middle stay 1j3 has a convex cross section and extends from the inclined surface 1h1 in a convex shape with the same height and width. Furthermore, the height of the upper middle stay 1j3 is lower than the stays 1j1 and 1j2. This is to prevent the stud from becoming unable to swing as described above.

[0043] 4, a stay 1j4 (also referred to as a lower middle stay 1j4) is provided on the lower inclined surface 1h2 of the connecting portion 21h of the bar grip portion 21j, extending parallel to the stays 1j1 and 1j2 at the middle of the stays 1j1 and 1j2. The lower middle stay 1j4 has a convex cross section, is taller than the stays 1j1 and 1j2, and extends from the bar grip portion 21j to the dome portion 21g.

[0044] 1, the lower end line of the lower middle stay 1j4 extends at the same height as the lower end line of the bar grip portion 21j extending parallel to the equator H. The lower end line of this lower middle stay 1j4 is located lower than the lower end lines of the both side stays 1j1, 1j2. Therefore, the absolute height of the lower middle stay 1j4 itself is high, and the strength is accordingly increased, further increasing the strength connecting the bar grip portion 21j and the dome portion 21g.

[0045] In this manner, the two side stays 1j1, 1j2, the upper middle stay 1j3 and the lower middle stay 1j4 reinforce the connection between the body portion 21b of the housing 21 and the bar grip portion 21j.

[0046] However, the thickness of the width perpendicular to the equator H of each of the stays 1j1 to 1j4, for example the thickness t1 of the width shown representatively by the upper middle stay 1j3 in Fig. 5, is basically 3 mm, and is preferably between 2 and 4 mm. At least two stays, 1j1 and 1j2 on both sides, which constitute the above-mentioned double stay structure, are required.

[0047] Further, each of the stays 1j1 and 1j2 may be configured such that the upper side of the connection portion 21h (see FIG. 3) extends to the flange portion 21d and the upper end portion 21f of the body portion 21b.

[0048] If the stays 1j1, 1j2 on both sides are separated above and below the equator H, a total of two stays are required on both sides above the equator H and two stays on both sides below. In addition to the stays on both sides, an upper middle stay 1j3 and a lower middle stay 1j4 are used to make three stays on each side, which further increases the reinforcing strength. Alternatively, a configuration may be used in which a total of two stays are provided on both sides above the equator H and one stay is provided in the middle on the lower side.

[0049] Next, as shown in Fig. 4, dome portion 21g is provided with a plurality of reinforcing ribs 21k that protrude radially (see Fig. 6). These ribs 21k serve to reinforce dome portion 21g, which has a reduced strength due to the change from the double flange structure of the conventional double flange portions 11g, 11k (Fig. 18) to the single flange structure of single flange portion 21d.

[0050] 2, each rib 21k forms a triangular shape (shaded portion with narrow gap) on the side that is surrounded by a tangent k1 extending from a position (indicated by arrow Y2) on a concentric circle spaced a predetermined distance from the center (indicated by arrow Y1) of dome portion 21g to the circumferential edge of flange portion 21d, the hemispherical surface of dome portion 21g, and the lower surface of flange portion 21d. By providing ribs 21k with this triangular shape on the side radially from the center of the hemispherical surface, the strength of dome portion 21g is increased.

[0051] In this example, as shown in FIG. 6, the angle θ2 between the ribs 21k is 25 degrees, and the angle θ3 between the ribs 21k at both ends in the circumferential direction that spread radially is 200 degrees. That is, the ribs 21k are provided at equal intervals in the circumferential direction. The angle θ3 is at least 180 degrees or more, and may be an angle at which the ribs 21k at both ends of the radial shape do not come into contact with the stays 1j1 and 1j2 on both sides. The angle θ2 between the ribs 21k may be an angle that provides a reinforcing strength that does not damage the dome portion 21g when the ball portion 10b swings. The number of ribs 21k provided can be changed by changing such angles θ2 and θ3.

[0052] For example, by setting the arrangement interval of the ribs 21k according to the angle θ2 to 10 mm or less, it is possible to effectively protect the dome portion 21g from external impact. It is preferable that the thickness t2 of the rib 21k is basically 1 to 3 mm and is changed according to the required reinforcing strength.

[0053] <Configuration without ball seat> The above-described ball joint J1 may be a ball joint J2 without the ball seat 30, as shown in FIG.

[0054] In the ball joint J2, the body 21b of the housing 21 has a housing inner spherical surface 21a that directly includes the ball portion 10b up to the position of the opening 21c. In addition, a horizontal surface 1f2 that goes around horizontally is provided below the tapered portion 1f1 that goes around the inside of the upper end 21f of the body 21b. The horizontal surface 1f2 prevents the ball portion 10b from coming off.

[0055] In this way, PA66 (Polyamide 66) + GF30 (a material made of PA66 with 30% glass fiber by weight) is used for the housing 21 when the ball seat 30 is not included. By using this material, when the ball portion 10b is directly held by the housing 21, the torque is reduced and the surface pressure is lowered, improving the spread of grease.

[0056] However, the material of the housing 21 may be any material that satisfies the strength requirements, for example, engineering plastics such as PEEK (polyetheretherketone), PA6 (Polyamide 6), PPS (Poly Phenylene Sulfide Resin), and POM (polyoxymethylene), super engineering plastics, and CFRP (Carbon Fiber Reinforced Plastics) are used.

[0057] In addition, by using GF (Carbon Fiber) 50 for the housing 21, the amount of molding shrinkage can be reduced even with the same shape, and further torque reduction can be achieved.

[0058] The inner spherical surface 21a of the housing 21, which is insert-molded from such a thermoplastic resin, has a predetermined wear resistance because the ball portion 10b of the ball stud 10 sways and slides on the inner spherical surface 21a.

[0059] <Effects of the embodiment> The effect of the ball joint J1 (or J2) according to this embodiment will be described below. The ball joint J1 includes a ball stud 10 having a metal ball portion 10b integrally joined to one end of a stud portion 10s, the other end of which is connected to a structure, and a resin housing 21 having an inner spherical surface 21a that encompasses the ball portion 10b and has an open space through which the stud portion 10s joined to the ball portion 10b can protrude.

[0060] (1) The housing 21 includes a body portion 21b having an inner spherical surface 21a that includes the ball portion 10b up to the position of the opening, a flange portion 21d that is disposed on the outer circumferential surface of the body portion 21b on an equator H that virtually passes through the center of the ball portion 10b and protrudes in an annular manner, and a dome portion 21g that protrudes hemispherically along the inner spherical surface 21a below the flange portion 21d. Furthermore, the housing 21 includes a bar grip portion 21j to which a support bar 100 that is connected to the other ball joint is fixed.

[0061] The bar grip portion 21j has a cylindrical shape and includes a cylindrical portion into which the support bar 100 is inserted, a connection portion 21h that connects the flange portion 21d along a horizontal line H, and at least two stays 1j1, 1j2 (two stay portions) that extend from the cylindrical portion to the flange portion 21d and the dome portion 21g along the upper or lower side of the connection portion 21h.

[0062] According to this configuration, at least two spaced apart stays 1j1, 1j2 are provided that connect the annular flange portion 21d and dome portion 21g protruding from the outer circumferential surface of the body portion 21b in the housing 21 to the bar grip portion 21j along the equator H. These stays 1j1, 1j2 can reinforce the connection between the body portion 21b (flange portion 21d and dome portion 21g) and the bar grip portion 21j. Since the stays 1j1, 1j2 extend along the equator H, the housing mold for insert molding the ball joint J1 can be formed by dividing it into two parts in the vertical direction along the equator H.

[0063] Conventionally, the housing type could be divided into two parts vertically and had a slide type that could slide left and right along the equator H. This slide type required width. For example, the width was about 300 mm.

[0064] However, in this embodiment, the housing mold for insert molding the ball joint J2 (FIG. 7) can be formed by dividing it into two parts in the vertical direction along the equator H. This eliminates the need for lateral sliding as in the past, allowing the width to be narrower. As a specific example, this width can be approximately 100 mm. In this way, according to the ball joint J2 of this embodiment, the width of the housing mold for insert molding the ball joint J2 can be reduced.

[0065] This allows the number of housing molds that can be placed on one base to be increased, thereby increasing the number of ball joints that can be insert molded at one time, thereby reducing equipment costs and production takt time.

[0066] (2) The two stays 1j1, 1j2 are configured to extend from the cylindrical portion of the bar grip portion 21j along the underside of the connection portion 21h to the flange portion 21d and the dome portion 21g.

[0067] According to this configuration, the stays 1j1 and 1j2 connect the flange portion 21d and the dome portion 21g to the bar grip portion 21j, so that the connection strength between the bar grip portion 21j and the body portion 21b can be further reinforced.

[0068] (3) The two stays 1j1, 1j2 are configured to extend from the cylindrical portion of the bar grip portion 21j to the body portion 21b along both the upper and lower sides of the connection portion 21h.

[0069] According to this configuration, the stays 1j1 and 1j2 can further reinforce the connection strength between the bar grip portion 21j and the body portion 21b.

[0070] (4) A dust cover 13 for dust prevention is provided between an upper position spaced away from the ball portion 10b of the ball stud 10 toward the structure and an annular surface of the flange portion 21d facing the structure. The flange portion 21d is configured to be disposed on the line of the equator H.

[0071] According to this configuration, by locating flange portion 21d on the line of equator H, the attachment position of dust cover 13 to lower flange portion 21d can be aligned with the center of ball portion 13b. In the case of single flange portion 21d (FIG. 2) aligned with the center of ball portion 13b, the length from the center of ball portion 10b to opening 21c can be made shorter than in the conventional double flange structure (see FIG. 18).

[0072] Therefore, when the housing is molded using the housing mold, the lifting length required to lift the stud portion 10s and the center block corresponding to the ball portion 10b is shorter than in the conventional double flange structure, and the torque required to lift the stud portion 10s can be reduced.

[0073] In addition, the distance between the position above the ball portion 10b of the ball stud 10 and the upper surface of the flange portion 21d for attaching the dust cover 13 can be made shorter than in the conventional double flange structure. This allows the dust cover 13 to be made more compact.

[0074] (5) The connection portion 21h of the bar grip portion 21j has a downwardly inclined surface (upper inclined surface 1h1) that slopes downward toward the flange portion 21d and the dome portion 21g, and the two stays 1j1, 1j2 are configured to be inclined downwardly along the downwardly inclined surface.

[0075] With this configuration, when the ball stud 10 swings and tilts, the dust cover 13 becomes pinched between the bar grip portion 21j and the ball stud 10, preventing the ball stud 10 from becoming unable to swing at the required swing angle (preventing the stud from becoming unable to swing).

[0076] (6) The downwardly sloping upper surfaces of the two stays 1j1, 1j2 are configured to have tapered surfaces 1a, 2a that slope downward toward the horizontal line H on the side of the other stay 1j1, 1j2.

[0077] According to this configuration, by providing the tapered surfaces 1a, 2a on the downwardly sloping upper surfaces of the stays 1j1, 1j2, the prevention of the stud becoming unable to swing as described above can be more appropriately achieved.

[0078] (7) The dome portion 21g has a hemispherical outer peripheral surface provided with a plurality of ribs 21k that extend radially from a circle concentric with the center of the hemisphere.

[0079] According to this configuration, the multiple ribs 21k extend radially from the outer circumferential surface of the dome portion 21g, forming an arch shape with high strength. Therefore, the multiple ribs 21k can reinforce the dome portion 21g. Also, the ribs 21k are provided radially (see Figs. 4 and 10) along the semispherical shape of the dome portion 21g protruding below the ball joints J1 and j2, so they do not interfere with the vertical separation function of the housing type described above.

[0080] (8) The plurality of ribs 21k are configured so that the angle between the ribs 21k on both ends in the circumferential direction that extend radially is at least 180 degrees or more.

[0081] According to this configuration, the radially expanding ribs 21k are formed over at least half of the hemispherical dome portion 21g, thereby increasing the reinforcing strength of the dome portion 21g provided by the ribs 21k.

[0082] (9) The multiple ribs 21k are provided at equal intervals around the circumference of the hemispherical dome portion 21g.

[0083] According to this configuration, the radially expanding ribs 21k are provided at equal intervals in the circumferential direction of the hemispherical dome portion 21g, so that the force of reinforcing the dome portion 21g of each rib 21k is uniform. This makes it possible to further increase the reinforcing strength of the dome portion 21g. In other words, it is possible to further increase the strength that protects the dome portion 21g from external impacts.

[0084] (10) As in the ball joint J1 (FIG. 2), the ball joint further includes the ball seat 30 that is provided between the ball portion 10b and the housing inner spherical surface 21a and that encloses the ball portion 10b.

[0085] According to this configuration, the ball joint J1 having the housing 21 with the ball seat 30 shown in FIG. 2 can also obtain the same effects as the above-mentioned ball joint J2 (FIG. 7).

[0086] <First Modification of the Embodiment> FIG. 8 is a side view showing the configuration of a ball joint according to the first modification of the embodiment of the present invention.

[0087] The ball joint J2 of Modification 1 shown in Fig. 8 differs from the ball joint J1 of the embodiment (Fig. 1) in that, as shown in Fig. 9 or 10, the shapes of the stays 1j5, 1j6 on both sides and the upper middle stay 1j7 (see Fig. 9) and the lower middle stay 1j8 (see Fig. 10) between these stays 1j5, 1j6 are as follows: where, reference numeral 21A denotes a housing.

[0088] The two side stays 1j5, 1j6 are provided so as to extend from both side portions of the upper inclined surface 1h1 and the lower inclined surface 1h2 of the connection portion 21h of the bar grip portion 21j shown by dashed lines in Figure 8 (both side portions in the width direction perpendicular to the equator H in the horizontal direction (see Figures 11 and 12)) to a diameter position perpendicular to the equator H in the horizontal direction of the flange portion 21d as follows.

[0089] That is, the stays 1j5, 1j6 on both sides are spaced apart from each other as they move away from the cylindrical portion of the bar grip portion 21j, as shown in Fig. 11 or 12. Furthermore, each stay 1j5, 1j6 extends from both sides of the bar grip portion 21j through both sides of the upper inclined surface 1h1 and the lower inclined surface 1h2, and further extends to the above-mentioned annular diameter position through the edge portions of the annular upper and lower surfaces of the flange portion 21d. Also, as shown in Fig. 12, the tip portions of the stays 1j5, 1j6 joined (connected) to the lower side of the flange portion 21d are joined to the radial ribs 21k on both ends and extend to the above-mentioned diameter position.

[0090] The side shape of each stay 1j5, 1j6 is a triangle (see FIG. 9) as follows. That is, as shown in FIG. 8, the width is slightly narrower than the width between the top and bottom of the bar grip portion 21j, and the upper end line slopes downward and the lower end line slopes upward toward the flange portion 21d, forming a narrower triangle. The strength of the stays 1j5, 1j6 in this triangle shape is high, so that the connection strength between the flange portion 21d and the bar grip portion 21j can be further increased.

[0091] The upper end side of each stay 1j5, 1j6 is inclined along an upper inclined surface 1h1 as shown in Fig. 9, and further has tapered surfaces 5a, 6a that slope downward toward the other stay as shown in Fig. 11. The inclination along the upper inclined surface 1h1 of each stay 1j5, 1j6 and the tapered surfaces 5a, 6a are formed to prevent the stud from becoming unable to swing as described above.

[0092] In addition, the lower end side of each stay 1j5, 1j6 is inclined along a lower inclined surface 1h2 as shown in FIG. 10, and further has tapered surfaces 5b, 6b that are inclined downward toward the other stay as shown in FIG.

[0093] As shown in Fig. 9, the upper intermediate stay 1j7 is provided between the stays 1j5 and 1j6 on the upper inclined surface 1h1 of the connecting portion 21h and extends parallel to them. The upper intermediate stay 1j7 has a convex cross section, is higher than the stays 1j5 and 1j6 on the both sides (see Fig. 8), and extends away from the upper end 21f of the body portion 21b so as to be connected to the circumferential edge of the flange portion 21d. The end face 7a of the upper intermediate stay 1j7, which is away from the upper end 21f, is a tapered end face 7a that slopes downward toward the upper end 21f.

[0094] The downward inclination above the flange portion 21d of each of the two stays 1j5, 1j6 and the tapered end surface 7a are formed to prevent the stud from becoming unable to swing as described above.

[0095] Next, the lower intermediate stay 1j8 is provided on the lower inclined surface 1h2 of the connecting portion 21h between the stays 1j5 and 1j6 and extends parallel to them, as shown in Fig. 10. The lower intermediate stay 1j8 has a convex cross section and extends from the bar grip portion 21j to the dome portion 21g at a height higher than the stays 1j5 and 1j6.

[0096] 8, the lower end line of the lower intermediate stay 1j8 extends at the same height as the lower end line of the bar grip portion 21j extending parallel to the equator H. This lower end line is located lower than the lower end lines of the two side stays 1j5, 1j6. Therefore, the absolute height of the lower intermediate stay 1j8 itself is high, and the strength is accordingly increased, further increasing the strength connecting the bar grip portion 21j and the dome portion 21g.

[0097] However, the thickness of the width perpendicular to the equator H of each of the stays 1j5-1j8, for example the thickness t3 of the width shown representatively by the upper middle stay 1j7 in Fig. 11, is basically 3 mm, and is preferably between 2 and 4 mm. At least two stays, 1j5 and 1j6 on both sides, which constitute the above-mentioned double stay structure, are required.

[0098] In this manner, the two side stays 1j5, 1j6, the upper middle stay 1j7 and the lower middle stay 1j8 of the ball joint J2 reinforce the connection between the body portion 21b (flange portion 21d and dome portion 21g) of the housing 21 and the bar grip portion 21j.

[0099] The stays 1j5 and 1j6 on both sides of the ball joint J2 are longer and have a larger side area than the stays 1j1 and 1j2 (FIG. 1) of the above-mentioned ball joint J1, and further have a larger joining area to the flange portion 21d. Therefore, the stays 1j5 and 1j6 of the ball joint J2 can reinforce the connection between the body portion 21b (flange portion 21d and dome portion 21g) of the housing 21 and the bar grip portion 21j more firmly than the stays 1j1 and 1j2 of the ball joints J1 and J2.

[0100] <Modification 2 of the embodiment> FIG. 13 is a side view showing the configuration of a ball joint according to Modification 2 of the embodiment of the present invention.

[0101] The ball joint J3 of the modified example 2 shown in Fig. 13 differs from the ball joint J2 (Fig. 8) of the modified example 1 in three points, where reference numeral 21B denotes a housing.

[0102] The first point is that the upper and lower thicknesses t1 of the flange portion 21dB of the ball joint J3 are made thicker than the flange portion 21d (FIG. 8) of the ball joint J2.

[0103] The second point is that, as shown in FIG. 14, the diameter D1 of the upper end 21fB of the body 21b is made larger than the upper end 21f of the ball joint J2, and the thickness t2 of the upper end 21fB is made thicker.

[0104] The third point is that the area of ​​the triangular side surface of each of the stays 1j5B, 1j6B (see FIG. 16) of the bar grip portion 21j shown in FIG. 13 is made larger than the area of ​​the triangular side surface of the ball joint J2.

[0105] 13, the flange portion 21dB is raised upward to increase the thickness t1, and the height of the upper end portion 21fB is reduced by the amount of the raised portion.

[0106] Furthermore, each stay 1j5B, 1j6B of the bar grip portion 21j forms a narrowing triangular shape with an upper end line sloping downward and a lower end line sloping upward from the upper and lower ends of the bar grip portion 21j toward the upper and lower surfaces of the center through which the vertical line V of the flange portion 21dB passes. This triangular shape connects the upper and lower ends of the bar grip portion 21j with the upper and lower surfaces of the center of the flange portion 21dB, which has a thicker thickness t1, and therefore has a larger area than the triangular shape of the ball joint J2.

[0107] As shown in Fig. 14, the upper end side of the stays 1j5B, 1j6B is inclined from the upper end of the bar grip portion 21j to the upper surface of the flange portion 21dB, and forms an inclined surface 1j10 having a recessed inclined portion 1h3 in the center. Both sides of the recessed inclined portion 1h3 are wide slope surfaces. This inclined surface 1j10 is formed to prevent the stud from becoming unable to swing as described above.

[0108] As shown in Fig. 15, the lower end sides of the stays 1j5B and 1j6B are inclined from the lower end of the bar grip portion 21j so as to be joined to the ribs 21k on both ends, forming an inclined surface 1j11 having a recessed inclined portion 1h4 in the center. Both sides of the recessed inclined portion 1h4 are wide slope surfaces. As shown in Fig. 16, the inclined surface 1j11 is provided with a lower intermediate stay 1j8B that connects from the lower end of the bar grip portion 21j through the center of the recessed inclined portion 1h4 to the dome portion 21g.

[0109] In the ball joint J3 configured as described above, the thickness t1 of the flange portion 21dB and the thickness t2 of the upper end 21fB of the body portion 21b are increased, and the stays 1j5B, 1j6B connecting the bar grip portion 21j and the housing 21B are also increased overall in size, thereby further increasing the strength of the entire ball joint J3.

[0110] <Modification 3 of the embodiment> FIG. 17 is a side view showing the configuration of a ball joint according to the third modified example of the embodiment of the present invention.

[0111] The ball joint J4 of the modified example 3 shown in Fig. 17 differs from the ball joint J3 of the modified example 2 (Fig. 16) in that a plurality of hexagonal recesses 21m are provided in a honeycomb pattern on the underside of the dome portion 21g side of the flange portion 21dC. However, the recesses 21m can also be expressed as holes or cavities. The recesses 21m may also be polygonal other than a hexagon, circular including an ellipse, or other shapes.

[0112] When the recess 21m is provided in this manner, the pressure can be increased when the resin is poured into the housing mold to insert-mold the housing 21C, thereby forming a stronger housing 21C with a higher density.

[0113] In addition, the specific configuration can be modified as appropriate without departing from the spirit of the present invention. The ball joints J1 to J4 having the ball seat fixing structure of the present invention are applicable to joints of robot arms such as industrial robots and humanoid robots, and to devices such as excavators and cranes where the arms rotate at joints. [Explanation of symbols]

[0114] 10 Ball Stud 10b Ball section 10s Stud section 13 Dust cover 21 Housing 21a Housing inner spherical surface 21b Torso 21c aperture 21d, 21dB, 21dC flange 21f Upper end 21f1 Tapered surface 21g Dome section 21h Connection 1h1 Upper slope (downward slope) 1h2 Lower slope 21j Bar grip part 1j1,1j2,1j5,1j6,1j5B,1j6B Stay 1a, 1b, 5a, 5b, 6a, 6b Tapered surface 1j3,1j7 Upper middle stay 7a Tapered end face 1j4, 1j8, 1j8B Lower intermediate stay 21k Rib 21m depression 30 Ball seat 100 Support Bar J1, J2, J3, J4 ball joints

Claims

1. A ball joint comprising: a ball stud having one end connected to a structure and the other end of a stud having a metallic spherical portion integrally joined thereto; and a resin housing having an inner spherical surface that contains the spherical portion and has an open space through which the stud portion joined to the spherical portion can protrude, The housing includes: a body portion having an inner spherical surface that includes the spherical portion up to the position of the opening; a flange portion that is disposed on the outer circumferential surface of the body portion along a horizontal line that virtually passes through the center of the spherical portion and that protrudes in an annular manner; a dome portion protruding hemispherically along the inner spherical surface below the flange portion; a bar grip portion to which a support bar connected to the other ball joint is fixed, The bar grip portion is A cylindrical portion having a cylindrical shape and into which the support bar is inserted; a connection portion that connects the flange portion and the dome portion to the cylindrical portion along the horizontal line; At least two stay portions extending from the cylindrical portion to the flange portion along at least an upper side of the connection portion, a dust cover is provided between a position of the ball stud spaced from the spherical portion toward the structure and an annular surface of the flange portion facing the structure; The flange portion is disposed on the horizontal line, The connection portion of the bar grip portion has an inclined surface that is inclined toward the horizontal line from the opening side, The two stay portions are provided in an inclined manner along the inclined surface. A ball joint characterized by

2. The inclined upper surface of the two stay portions has a tapered surface that is inclined toward the horizontal line on the other stay portion side.

2. The ball joint of claim 1.

3. A plurality of ribs extending radially from a concentric circle with respect to the center of the hemisphere are provided on the hemispherical outer circumferential surface of the dome portion.

3. The ball joint according to claim 1 or 2, further comprising:

4. The plurality of ribs are arranged so that the angle between the ribs at both ends in the circumferential direction of the radially extending ribs is at least 180 degrees.

4. The ball joint according to claim 3.

5. The plurality of ribs are provided at equal intervals in the circumferential direction of the hemispherical dome portion.

5. A ball joint according to claim 3 or 4.

6. A ball joint comprising: a ball stud having one end connected to a structure and the other end of a stud having a metallic spherical portion integrally joined thereto; and a resin housing having an inner spherical surface that contains the spherical portion and has an open space through which the stud portion joined to the spherical portion can protrude, The housing includes: a body portion having an inner spherical surface that includes the spherical portion up to the position of the opening; a flange portion that is disposed on the outer circumferential surface of the body portion along a horizontal line that virtually passes through the center of the spherical portion and that protrudes in an annular manner; a dome portion protruding hemispherically along the inner spherical surface below the flange portion; a bar grip portion to which a support bar connected to the other ball joint is fixed, The bar grip portion is A cylindrical portion having a cylindrical shape and into which the support bar is inserted; a connection portion that connects the flange portion and the dome portion to the cylindrical portion along the horizontal line; At least two stay portions extending from the cylindrical portion to the flange portion along the upper and lower sides of the connection portion, The connection portion of the bar grip portion has an inclined surface that is inclined toward the horizontal line from the opening side, The two stay portions are provided to extend from both sides of the connection portion in a width direction perpendicular to the horizontal line to a diameter position of the flange portion perpendicular to the horizontal line, The two stay portions form a triangular shape in which the upper end side on the opening side and the lower end side opposite to the upper end side are inclined toward the horizontal line from the bar grip portion toward the flange portion. A ball joint characterized by

7. An upper intermediate stay portion is provided between the two stay portions of the inclined surface of the connection portion, and extends parallel to the two stay portions, spaced apart from the body portion, from the bar grip portion to a circumferential edge portion of the flange portion, The end surface of the upper intermediate stay portion separated from the body portion is a tapered end surface inclined toward the horizontal line.

7. A ball joint as claimed in claim 6.

8. A lower intermediate stay portion is provided on the back surface of the inclined surface of the connecting portion, between the two stay portions, in parallel with the two stay portions, so as to be connected from the bar grip portion to the dome portion.

8. A ball joint according to claim 6 or 7.

9. A ball seat that includes the spherical portion and is provided between the spherical portion and the inner spherical surface.

9. The ball joint according to claim 1, further comprising:

10. A plurality of recesses are provided on the lower surface of the flange portion on the dome portion side.

10. A ball joint according to claim 1 , wherein the ball joint is a ball joint having a diameter of 100 mm or less.

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