Ball joint

1. A ball joint comprising:

a ball stud that has a stud portion with one end being coupled to a structure body and the other end being joined in one piece with a spherical body portion;

a housing that includes a space in which the spherical body portion of the ball stud is supported swingably and rotatably; and

a support member that is arranged between the housing and the spherical body portion,

wherein the support member is an elastic body having a given thickness, and has a first opening for the stud portion to protrude therethrough and a spherical space inside to accommodate the spherical body portion therein,

wherein a thickness of the support member at a lower portion closer to an opening at a lower side is in a tapered shape that is gradually thinner toward the opening at the lower side from a portion of the support member at a level of a center position of the spherical body portion that is accommodated in a spherical space of the support member, and

wherein the housing has a spherical inner face along an outer periphery of the spherical body portion, and the support member that is displaceably pressed by a pressure regulating member is arranged between the outer periphery of the spherical body portion that is inserted toward the spherical inner face.

2. The ball joint according to claim 1 ,

wherein the housing has a clamped portion as the pressure regulating member at a peripheral end of the housing, and

wherein the clamped portion has a shape to be clamped so as to press the support member so that the ball portion accommodated in the spherical inner face of the housing via the support member is swingable and rotatable.

3. The ball joint according to claim 2 ,

wherein clamping with the clamped portion is made to set a tightening margin between the housing and the support member by the clamping such that a swing-and-slide torque of the ball stud is 0.5 Nm or less.

4. The ball joint according to claim 1 ,

wherein the support member is in a tubular shape that includes a second opening that opens on an opposite side of the first opening.

5. The ball joint according to claim 4 ,

wherein a diameter of the first opening of the support member is [90%±5%] of a spherical diameter passing through a center of the ball portion.

6. The ball joint according to claim 4 ,

wherein an end of the second opening of the support member is set to a position, where the support member intersects with a straight line that forms an angle θ 1 at a center of the ball portion with a reference line passing through the center, and the angle θ 1 is set in a range satisfying [41°≤θ 1 ≤49°].

7. The ball joint according to claim 6 ,

wherein a thickness of the support member from the reference line to a lower end of the housing is set between 0.4 mm and 2.0 mm.

8. The ball joint according to claim 4 further comprising at least one groove that is formed in a concave shape having a given width from the first opening toward the second opening in an inner face of the spherical space of the support member,

wherein a depth of the groove is set in a dimensional range between 0.1 mm and 0.5 mm.

9. The ball joint according to claim 4 ,

wherein the housing includes a recess circumferentially formed in a concave groove shape between the first opening and the second opening in the spherical inner face, and

wherein a support portion is formed in the recess to receive a lower end of the support member when the clamped portion is clamped, after the support member is arranged in the recess.

10. The ball joint according to claim 4 ,

wherein a spherical inner face of the housing is formed such that a cross-sectional shape of a gap between the spherical inner face of the housing and an outer periphery of the spherical body portion is in a taper shape from a level of a center position of the spherical body portion toward the second opening.

11. The ball joint according to claim 1 ,

wherein a taper angle θ 2 of the lower portion in a taper shape of the support member is in a range satisfying [2°≤θ 2 ≤14.5°].

12. The ball joint according to claim 1 ,

wherein a thickness at the lower portion in a taper shape of the support member is set to be 0.4 mm or more.