1. Field of the Invention
The present invention relates to a ball joint used for a connecting portion in a stabilizer for automobiles and an assembling method therefor.
2. Related Art
FIG. 4 shows such a conventional ball joint. The ball joint has a ball stud 2 having a spherical head 2a at an end thereof, and the head 2a is slidably fitted into a resin ball seat 3 which is contained in a cylindrical housing 4. The ball stud 2 is universally supported by the ball seat 3 so as to swing and rotate around the axis thereof. The ball seat 3 is formed with a rivet-shaped engaging portion 3b at the bottom thereof. The engaging portion 3b penetrates the bottom of the housing 4 and engages with the bottom, whereby the ball seat 3 is secured to the housing 4 and is prevented from rotating and separating with respect to the housing 4. Reference numeral 6 is a lamp shade-shaped dust cover and reference numeral 7 is a supporting bar which is integrally secured to the housing 4.
The above ball joint is assembled in the following manner. As shown in FIG. 5, plural protrusions 3a are integrally formed at the bottom of the ball seat therewith. As shown in FIG. 6, the bottom of the housing 4 is formed with through holes 4a into which the protrusions 3a are inserted. In assembling a ball joint, the spherical head 2a of the ball stud 2 is fitted into the ball seat 3; then, the ball seat 3 is fitted into the housing 4 when inserting the protrusions into the through holes 4a. Subsequently, the protrusions 3a projecting from the through holes 4a are heated by a heater, or the like, and are crushed to form an engaging portion 3b as shown in FIG. 6.
According to the ball joint, since the engaging portions 3b of the ball seat project from the bottom of the housing 4, the size in the height direction (axial direction) cannot be short. Moreover, the ball seat 3 is loaded with forces to rotate and pull it out with respect to the housing 4 via the ball stud 2. When the force is too large, the engaging force of the engaging portion may not be sufficient to prevent such movement in some cases. In order to cope with this problem, it may be proposed to thicken the diameter of the protrusion 3a of the ball seat 3 and the engaging portion 3b or the thickness thereof. However, by doing so, disadvantages in which the housing 4 is large and the protrusion 3b is elongated may increase. That is, it has been difficult to reconcile efficient engaging force of the ball seat 3 and compact design of the ball joint.
An object of the present invention is to provide a ball joint and an assembling method therefor, in which the engaging force of a portion which functions for preventing from rotating and pulling the ball seat out can be sufficiently ensured and compact design can be obtained.
The present invention provides a ball joint comprising: a ball stud having a spherical head at an end thereof; a ball seat into which the spherical head is slidably fitted so as to universally support the ball stud; and a housing for accommodating the ball seat. The ball seat and the housing have surfaces opposing each other, and recesses communicated with each other are formed on the surfaces. The recesses are filled with a resin, so that relative movement of the ball seat with respect to the housing is restricted.
According to the ball joint of the invention, since the relative movement of the ball seat with respect to the housing is restricted, rotation and pulling out of the ball seat from the housing can be prevented. Since the resin is filled in the interior of the housing, the size of the ball joint is not increased by the resin. The engaging force with respect to the relative movement can be increased by suitably designing the size, depth, and the shape of the recess and by selecting the material of the resin. Therefore, the engaging force of the ball seat with respect to the housing to prevent from rotating and pulling the ball seat out can be sufficiently ensured and the design can be compact.
The present invention provides an assembling method for a ball joint comprising: a ball stud having a spherical head at an end thereof; a ball seat into which the spherical head is slidably fitted so as to universally support the ball stud; and a housing for accommodating the ball seat. The ball seat and the housing have surfaces opposing each other, and recesses communicated with each other are formed on the surfaces. The recesses are filled with a resin, so that relative movement of the ball seat with respect to the housing is restricted. A resin charging opening for charging the resin in the recesses is formed in the housing. The spherical head is fitted into the ball seat, the ball seat is accommodated in the housing, a liquid resin is charged from the resin charging opening to the recesses, and the resin is hardened. According to the assembling method of the invention, the ball joint of the invention can be suitably assembled.