JP2021099139A - Ball joint - Google Patents

Abstract

To provide a ball joint which eases stress concentration at a bottom part of a retainer which receives a ball part to achieve a long life of the retainer.SOLUTION: A ball joint includes: a ball stud having a ball part and a shaft part protruding in a radial direction from an outer peripheral surface of the ball part; and a retainer formed of an elastic material and having a recessed part, in which the ball part may be fitted and which has a substantially spherical shape, and a through hole penetrating downward from a bottom surface of the recessed part. In the through hole, an inner peripheral surface inclines so that a bore diameter increases from one opening located at the front surface side of the recessed part to the other opening located at the opposite side of the through hole with respect to the one opening.SELECTED DRAWING: Figure 1

Description

The present invention relates to a ball joint used for a suspension portion of a vehicle, an arm portion of a robot, and the like.

Conventionally, a ball stud having a ball portion, a socket (housing), and a sliding member housed in the socket are provided as a ball joint, and the ball portion rotates into a substantially spherical recess of a holding body (receiving portion). Those that are slidably held are known (Patent Documents 1 to 3).
Further, in order to improve the rotational slidability of the ball portion, it has been proposed to arrange a fiber cloth impregnated with rubber or resin in the recess of the holding body (Patent Document 4).

In such a ball joint, the holding body that receives the ball portion applies stress such as an impact to the bottom portion in contact with the ball portion. However, since stress tends to concentrate on a part of the bottom of the holder, the bottom of the holder wears in a relatively short period of time and reaches the end of its life.

Japanese Patent No. 4863638 Japanese Unexamined Patent Publication No. 2012-021600 Japanese Unexamined Patent Publication No. 2012-17751 Japanese Patent No. 5975783

An object of the present invention is to provide a ball joint that relaxes stress concentration at the bottom of a holder that receives a ball portion and extends the life of the holder.

The ball joint of the present invention is made of a ball stud having a ball portion and a shaft portion protruding in the radial direction from the outer peripheral surface of the ball portion, an elastic material, and a substantially spherical recess into which the ball portion can be fitted. A holding body having a through hole penetrating downward from the bottom surface of the recess is provided. The through hole has an inner peripheral surface such that the diameter increases from one opening located on the surface side of the recess toward the other opening located on the opposite side of the through hole with respect to the one opening. Is sloping.

According to the present invention, the holding body has a through hole penetrating downward from the bottom surface of a substantially spherical recess into which the ball portion can be fitted, and the through hole has an inclined inner peripheral surface, so that it is an elastic material. Even if stress due to rotational sliding of the ball is applied to the bottom of the holder, the stress is dispersed and the bottom of the holder is suppressed from being worn, and as a result, the life of the holder can be extended. it can.

It is sectional drawing of the ball joint which concerns on one Embodiment of this invention. It is a partial cross-sectional view which shows the vicinity of the bottom part of the holding body in a ball joint. It is the schematic which shows the simulation result which shows the pressure distribution of the holding body shown in FIG. 2 which concerns on Example. It is a partial cross-sectional view which shows the vicinity of the bottom part of the holding body which becomes the comparative example of this invention. It is a schematic diagram which shows the simulation result which shows the pressure distribution of the holding body as a comparative example.

Hereinafter, the ball joint according to the embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the ball joint 100 includes a ball stud 1, a housing 2, a holding body 3 housed inside the housing 2, and a dust cover (cover member) 4.

(Ball stud)
The ball stud 1 is made of a metal material and has a ball portion 11 housed inside the housing 2 and a shaft portion 12 protruding in the radial direction from the outer peripheral surface of the ball portion 11. The ball portion 11 is held by the holding body 3, and a sliding member 5 is arranged between the ball portion 11 and the holding body 3. The sliding member 5 is provided along the outer peripheral surface of the ball portion 11, and is integrated with the dust cover 4 by extending the upper portion into the dust cover 4. Further, the holding body 3, the dust cover 4, and the sliding member 5 are integrally molded.

(housing)
The housing 2 is a metal member having openings at the upper and lower ends, and is provided with openings 21 at the lower ends. An edge portion 22 protruding toward the internal space is formed at the upper end portion of the housing 2, and the edge portion 22 prevents the holding body 3 from coming out of the housing 2.

(Holder)
The holding body 3 is made of an elastic material such as resin or rubber, and is made of a material having a lower elastic modulus than the sliding member 5. Further, the holding body 3 is softer than the sliding member 5.

That is, examples of the elastic material constituting the retainer 3 include natural rubber, nitrile rubber, chloroprene rubber, hypolon, polybutadiene rubber, ethylene-propylene rubber (EPM), and ethylene-propylene-diene ternary copolymer (EPDM). , Hydrogenated acrylonitrile butadiene rubber (H-NBR), silicon rubber, fluororubber, acrylic rubber, styrene butadiene rubber, chlorinated polyethylene rubber, miraculous urethane, thermosetting polyurethane, thermoplastic polyurethane or elastomers such as thermoplastic polyester. And one or more of these are used. The elastomer may contain a vulcanizing agent, a vulcanization accelerating aid and a reinforcing agent. Examples of the vulcanizing agent include organic peroxides such as dicumyl peroxide, organic sulfur compounds, and metal oxides. Examples of the vulcanization accelerator include fatty acids such as stearic acid and metal oxides. Examples of the reinforcing agent include carbon black and white carbon. Further, for example, anti-aging agents, fillers, plasticizers, pressure-sensitive adhesives and the like can also be blended. In addition to these, a solid lubricant such as graphite, silicone oil, fluorine powder, or molybdenum disulfide may be contained in order to reduce the sliding resistance.

The holding body 3 is formed with a substantially spherical recess 31 into which the ball portion 11 can be fitted and a through hole 32 penetrating downward from the bottom of the recess 31. The through hole 32 is a relief margin when the holding body 3 is pressed downward by the ball portion 11. Further, the holding body 3 is integrated with the dust cover 4.

The through hole 32 has a larger diameter from one opening 33 located on the surface side of the recess 31 toward the other opening 34 located on the opposite side of the through hole 32 with respect to the one through hole 32. , The inner peripheral surface is inclined. As a result, even if stress is applied to the holding body 3, the relief allowance of the holding body 3 is secured, so that the stress is dispersed and it is possible to prevent the stress from being excessively concentrated on a part of the holding body 3. Further, the through hole 32 communicates with the opening 21 at the lower end of the housing 2.

As shown in FIG. 2, when the diameter d1 of one opening 33 in the through hole 32 is D, the diameter d2 of the other opening is preferably 1.2D or more, preferably 1.2D to 1.5D. .. When the diameter d2 of the other opening 34 is smaller than 1.2D, the stress is not sufficiently dispersed, so that the holding body 3 is likely to be broken or worn.

The width d3 of the holding body 3 is preferably 1.5D or more, preferably 1.6D to 2D, where D is the diameter d1 of one opening 33 (however, the width d3 of the holding body 3> the other. The diameter d2 of the opening 34).
Further, the thickness t of the bottom portion of the holding body 3 (that is, the length parallel to the axial direction of the through hole 32) is preferably 0.03D to 0.1D, where D is the diameter d1 of one opening 33. Should be 0.05D or more. If the thickness t of the bottom portion of the holding body 3 is thinner than this, the wear resistance of the bottom portion of the holding body 3 may decrease.

The outer peripheral edge portion 33a of one opening 33 of the through hole 32 is preferably curved (R-shaped) or chamfered. As a result, the stress applied to the outer peripheral edge portion 33a can be dispersed.
For the same reason, the outer peripheral portion 35 of the bottom portion of the holding body 3 is also preferably curved (R-shaped) or chamfered.

(Dust cover)
Returning to FIG. 1, the dust cover 4 is a tubular member that covers the base end portion 12a of the shaft portion 12 of the ball stud 1 over the entire circumference, and has the same elasticity as the holding body 3 such as synthetic resin or rubber. It is made of material. The dust cover 4 has a bulging portion 41 bulging in the radial direction from the edge portion 22 of the housing 2 and a fixing portion 42 fixed to the shaft portion 12 above the bulging portion 41, and is in contact with the ball stud 1. Absent.
The bulging portion 41 is arranged away from the shaft portion 12, while the fixed portion 42 is in contact with the shaft portion 12. Further, a sliding member 5 is embedded in the lower end portion of the bulging portion 41 up to the height of the upper end portion of the housing 2. The bulging portion 41 is pulled or compressed in the inclined direction of the shaft portion 12 as the ball portion 11 rotates and slides.

The fixed portion 42 is formed in a substantially annular shape having a diameter smaller than that of the bulging portion 41, and the shaft portion 12 is inserted inside. Further, the fixed portion 42 is thicker than the bulging portion 41, and the vertical cross-sectional shape (one side sandwiching the center) is rectangular in length (height) longer than in width (horizontal length). A convex portion 44 protruding inward in the radial direction is formed on the inner peripheral surface of the fixed portion 42, and the fixed portion 42 is fixed to the shaft portion 12 by fitting the convex portion 44 into the concave portion 13 of the shaft portion 12. ing.

(Sliding member)
The sliding member 5 is arranged between the outer peripheral surface of the ball portion and the inner peripheral surface of the recess of the holding body, and is in contact with the contact portion 51 that abuts on the outer peripheral surface of the ball portion 11 so as to be separated from the ball portion 11. It has an extending portion 52 extending from the contact portion 51, and holds the ball portion 11 so as to be rotatable and slidable. The contact portion 51 is in contact with the ball portion 11, but the extending portion 52 is not in contact with the ball portion 11. Further, the sliding member 5 extends from the inner peripheral surface of the recess 31 of the holding body 3 to the inner peripheral surface of the through hole 32.

The sliding member 5 is made of a cloth impregnated with rubber or resin. Since cloth is used as the main body of the sliding member 5, the slidability of the ball portion 11 can be improved as compared with the sheet made of rubber or the like, and a gap between the sliding member 5 and the ball portion 11 is not generated. can do. Further, since the cloth is impregnated with rubber or resin, it is superior in abrasion resistance and shock absorbing power as compared with a sheet made of cloth alone, and has good adhesiveness to the holding body 3.

As the cloth of the sliding member 5, a cloth made of fibers (threads) of a general material can be used, and for example, aramid, nylon, urethane, cotton, silk, linen, acetate, rayon, and fluorine can be used. Weaving or knitting can be used by using fibers containing fibers, fibers (threads) made of materials such as polyester, and combinations thereof. Further, a non-woven fabric in which fibers (threads) are entwined can also be used.

The rubber impregnated in the cloth described above may be any rubber that can be impregnated with the cloth, for example, urethane rubber, nitrile rubber, silicon rubber, fluororubber, acrylic rubber, ethylene-propylene rubber, butyl rubber, isoprene rubber, chlorinated polyethylene. Rubber, epichlorohydrin rubber, hydride nitrile rubber, chloroprene rubber, polybutadiene rubber, styrene butadiene rubber, natural rubber and the like can be used alone, or these rubbers can be modified in various ways. These rubbers can be used alone or in a blend of a plurality of types of rubbers. Further, as the rubber, in addition to the vulcanizing agent, an appropriate amount of a vulcanization accelerator, an antiaging agent, a softening agent, a plasticizer, a filler, a colorant, etc., which have been conventionally used as a rubber compounding agent, is used. Can be blended. In addition to these, the rubber may contain a solid lubricant such as graphite, silicone oil, fluorine powder, or molybdenum disulfide in order to improve the lubricity of the cloth.

Examples of the resin impregnated in the cloth described above include acrylic resin, polyester resin, urethane resin, vinyl chloride resin, polypropylene, polycarbonate, PET resin, fluororesin, polyethylene, AS resin, ABS resin, PEEK resin, polystyrene resin, and poly. A thermoplastic resin such as vinyl chloride, polyvinylidene chloride, polyvinyl acetate, nylon, alkyd resin, phenol resin, epoxy resin, polyphenylene sulfide resin, or a thermosetting resin can be used.

As a method for impregnating the cloth with rubber or resin, first, the rubber or resin is dissolved in a solvent to make it liquid, and the cloth is dipped in the obtained solution (dipping treatment). The cloth is then removed and the excess solution is removed from the cloth and dried.

When the sliding member 5 manufactured by the above method is arranged between the outer surface of the ball portion 11 and the holding body 3, the sliding member 5 is adhered to the ball portion 11 and the holding body 3 by the impregnated rubber or resin. However, the use of an adhesive can further enhance these adhesiveness.

Next, a method of assembling the ball joint 100 will be described.
First, a member is prepared in which the sliding member 5 is attached to the inner surface of the holding body 3, and the holding body 3, the dust cover 4, and the sliding member 5 are integrally molded.
Next, the ball portion 11 of the ball stud 1 is fitted to the holding body 3, and the ball portion 11 is pressed against the sliding member 5 to assemble the ball stud 1 to the holding body 3. In the present embodiment, since the dust cover 4 and the sliding member 5 are integrated, the shaft portion 12 of the ball stud 1 becomes the dust cover 4 as the ball portion 11 is fitted to the holding body 3. The dust cover 4 is attached to the shaft portion 12 by being inserted inside. Subsequently, the holding body 3 to which the ball stud 1 is assembled is housed in the housing 2.

A member in which the holding body 3, the dust cover 4, and the sliding member 5 are integrally molded may be housed in the housing 2 in advance, and then the ball portion 11 may be fitted to the holding body 3.

As described above, the holding body 3 has a through hole 32 penetrating downward from the bottom surface of a substantially spherical recess 31 into which the ball portion 11 can be fitted, and the through hole 32 has an inclined inner peripheral surface. Therefore, even if stress is applied to the bottom of the holding body 3 made of an elastic material, the stress is dispersed, and the holding body 3 is prevented from being broken and worn at an early stage, and as a result, the life of the holding body 3 is extended. Can be planned.

Further, since the sliding member 5 made of cloth is arranged between the ball portion 11 and the holding body 3, the slidability of the ball portion 11 can be improved. Further, since the cloth of the sliding member 5 is impregnated with rubber or resin, the sliding member 5 has excellent wear resistance and shock absorption, so that a ball joint 100 having excellent durability can be obtained. it can.

Further, since the dust cover 4 and the sliding member 5 are integrally formed, the place where foreign matter enters the inside of the dust cover 4 is limited to the contact portion (fixing portion 42) of the dust cover 4 with the shaft portion 12. Therefore, the rate of foreign matter entering the dust cover 4 can be reduced.

Hereinafter, the ball joint of the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples.
(Example)
The pressure distribution of the holding body 3 having the shape shown in FIG. 2 was simulated by the FEM (finite element method).
The shape of the holder 3 used is as shown below.
Diameter d1: 12 mm of one opening 33
Diameter of the other opening 34 d2: 16 mm
Width d3 of holder 3: 24 mm
The outer peripheral edge portion 33a of one opening 33 has a curved surface shape (R shape), and the outer peripheral portion 35 of the bottom portion of the holding body 3 also has a curved surface shape (radius of curvature: 2.5 mm). The simulation results are shown in FIG.

(Comparison example)
The pressure distribution of the holding body 3'shown in FIG. 4 was simulated in the same manner as in the examples. The holding body 3'used was carried out except that the inner peripheral surface of the through hole 32'was not inclined, and therefore the diameter of one opening 33'and the diameter of the other opening 34'are the same 12 mm. It has the same shape as the holding body 3 of the example.
The simulation result for the holding body 3'shown in FIG. 4 is shown in FIG.

As shown in FIG. 5, the holding body 3'of the comparative example has stress concentrated particularly near the through hole 32', whereas as shown in FIG. 3, the holding body 3 of the example has the holding body 3 of the embodiment. It can be seen that the stress concentration near the through hole 32 is relaxed and the stress is dispersed.

1 Ball stud 2 Housing 21 Opening 3, 3'Retaining body 31 Recession 32, 32'Through hole 33, 33'One opening 34, 34'Other opening 35 Outer circumference 4 Dust cover 41 Swelling part 42 Fixed part 5 Moving member 11 Ball part 12 Shaft part 100 Ball joint 207 Holding sheet

Claims (5)

A ball stud having a ball portion and a shaft portion protruding in the radial direction from the outer peripheral surface of the ball portion,
A holding body made of an elastic material and having a substantially spherical recess into which the ball portion can be fitted and a through hole penetrating downward from the bottom surface of the recess are provided.
The through hole has an inner peripheral surface such that the diameter increases from one opening located on the surface side of the recess toward the other opening located on the opposite side of the through hole with respect to the one opening. A ball joint characterized by being tilted. The ball joint according to claim 1, wherein the diameter of the other opening is 1.2D to 1.5D, where D is the diameter of the one opening. The ball joint according to claim 1 or 2, wherein the outer peripheral edge portion of the one opening has a curved surface shape or a chamfered shape. A sliding member is arranged at least between the outer peripheral surface of the ball portion and the inner peripheral surface of the recess of the holding body so that the ball portion can rotate and slide, and the sliding member is made of rubber or resin. The ball joint according to any one of claims 1 to 3, which comprises a cloth impregnated with. The ball joint according to claim 4, wherein the sliding member extends from the inner peripheral surface of the recess to the inner peripheral surface of the through hole.

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