Ball Joint
A ball joint is provided that when a load equal to or greater than a first predetermined value is applied in the axial direction of a ball stud, if a cushion seat is deformed by a predetermined amount, an opposing surface portion contacts a first load receiving portion of a ball seat, preventing the cushion seat from being deformed by a predetermined amount in the central axis direction. When a load equal to or greater than a second predetermined value greater than the first is applied in the axial direction of the ball stud, a second load receiving portion of the ball seatcontacts a bottom surface portion of an inner chamber of a socket, whereby an axial load onto the cushion seat is reduced, and the ball seat prevents the cushion seat from being deformed by a predetermined amount or more in the axial direction.
1. A ball joint comprising:
a socket with an inner chamber having an opening portion at one end thereof and having a bottom surface portion at the other end thereof;
a bearing seat with an opening at one end thereof and housed in the inner chamber of said socket so that the opening is communicated with said opening portion;
a ball stud with a ball portion rotatably held by the bearing seat and housed in the inner chamber of said socket and a stud portion provided in a protruding manner from the ball portion and inserted through said opening and said opening portion; and
a cylindrical elastic member interposed between said bearing seat and an inner surface of said socket, the cylindrical elastic member being positioned apart from the bottom surface portion in a state where no load has been applied in an axial direction to the ball stud by an outside force and being provided with an opposing surface portion on an inner circumferential side thereof, wherein
said bearing seat comprises:
a first load receiving portion that has a cylindrical outer surface extending toward the bottom surface in a direction parallel to the axial direction, the first load receiving portion being configured opposite and apart from said opposing surface portion to define a gap between the first load receiving portion and said opposing surface portion when no load has been applied to the ball stud by an outside force in the axial direction, and being configured to come into contact with said opposing surface portion when an external force equal to or greater than a first predetermined value is applied to said ball stud in the axial direction, thereby preventing the cylindrical elastic member from being deformed toward the central axis by more than a predetermined amount; and
a second load receiving portion that is configured below the cylindrical elastic member and spaced apart from said bottom surface portion when no load has been applied to the ball stud by an outside force in the axial direction, such that a space between the second load receiving portion and said bottom surface portion is greater than the gap between the first load receiving portion and said opposing surface portion, and that is configured to come into contact with said bottom surface portion when an external force equal to or greater than a second predetermined value greater than said first predetermined value is applied to said ball stud in the axial direction, thereby preventing the cylindrical elastic member from being deformed toward the central axis by more than the predetermined amount in cooperation with the first load receiving portion.
2. The ball joint as set forth in claim 1 , wherein
the first load receiving portion is on an outer circumferential surface of an end portion of the bearing seat located at the bottom surface portion side of the socket, and the second load receiving portion, is at the end portion of the bearing seat, in a plane shape.