Ball Joint

This invention relates to a ball joint constituting part of a linkage mechanism for operating an automobile wiper or the like or of a door hinge mechanism of a hatchback automobile rear door, to hold a ball portion of a ball stud, thereby coupling together the ball stud and a rod or like work.

Japanese Patent Public Disclosure SHO No. 59-77120 discloses a plastic ball joint which comprises two halves of substantially the same shape each having a shell with a semi-spherical recess and a mounting portion provided on the shell for mounting it on a work. The two halves of the ball joint are coupled together by a hinge, and they are closed together by bending the hinge such that the recess of each of them holds one half of the ball portion of the ball stud. In this state, the ball joint is mounted on a panel with the mounting portions locked in a mounting hole formed in the panel.

In this ball joint, each mounting portion depends from the bottom portion of each shell, and the lower ends of the two mounting portions are linked by the hinge. Thus, by bending the hinge the two mounting portions are closed together into a single portion, while the two shells hold the ball portion of the stud with one half of the ball portion received in each recess. In this state, the mounting portions are inserted through the mounting hole of the work, whereby the ball joint is mounted on the work to thereby couple the work and ball stud. In this ball joint, however, the two recesses facing each other are disposed above the surface of the work when the ball joint is mounted. That is, a large space is required above the work, so that the ball joint is not suited for use in a small space. Further, although the mounting hole of the work maintains the two mounting portions enclosed and closed together, the two recesses holding the ball portion of the stud, particularly their portions adjacent to the open end enclosing a stem portion of the ball portion, are upwardly spaced apart from the mounting portions. Therefore, the mounting hole of the work, although it encloses the two mounting portions, does not substantially contribute to the holding together of the two recesses. In other words, it is necessary to separately provide means for strongly holding together the two recesses in the closed state. Otherwise, a strong force externally applied to the ball portion of the ball stud will cause detachment of the ball portion by forcing apart the two recesses.

An object of the invention is to provide a ball joint which can be readily used even in a small space and can reliably hold the ball portion of the ball stud against detachment even when a strong force is externally applied to the ball portion.

The ball joint according to the invention, like the prior art ball joint mentioned above, consists of a onepiece plastic molding. According to the invention, a connecting piece for engaging the bottom of the shells is provided, each of the halves is united by a hinge to each end of the connecting piece, and the mounting portions are provided on the side surface of the halves.

The two halves, which are united by the connecting piece, are joined together by bending the hinge at each end of the connecting piece. By so doing, the connecting piece comes to rest on the bottom of each shell, whereby a ball portion of a ball stud is held in the two recesses. When the ball joint in this state is forcibly inserted through a mounting hole formed in the work, the mounting portions provided on the side surface of the shells are hooked in the mounting hole of the work, so that the joint is mounted on the work with the shells enclosed in a face-to-face joined state in the mounting hole of the work. The ball joint according to the invention thus can be used in a small space as well. The detachment of the ball portion of the ball stud is prevented because the shells joined together are enclosed in the mounting hole of the work and are prevented from being forced part.

The above and other objects and features of the invention will become more apparent from the following detailed description with reference to the accompanying drawings.

FIG. 1 is an exploded perspective view showing an embodiment of the ball joint according to the invention;

FIG. 2 is a sectional view showing the ball joint of FIG. 1 mounted on a work;

FIG. 3 is a sectional view similar to but different in angle by 90.degree. from FIG. 2; and

FIG. 4 is a sectional view taken along line IV--IV in FIG. 3.

Referring to the Figures, reference symbols "A" and "B" designate halves of a ball joint according to the invention. These halves have substantially the same shape. They respectively have shells 2a and 2b having semi-spherical recesses 1 and anchor-shaped mounting portions 3a and 3b projecting obliquely from the opposite sides of the respective shells. The two halves "A" and "B" are linked by thin hinges 5a and 5b to respective ends of a connecting piece 4, which is adapted to engage the bottom surface 1' of the shells 2a and 2b. The halves "A" and "B" and connecting piece 4 are formed as a one-piece plastic molding.

The shells 2a and 2b have respective outer flanges 6a and 6b provided on their front side, on which recesses 1 of the shells are open. In this embodiment, the shells are provided with projections 7a and recesses 7b which engage one another when they are closed together. They are also provided with pawls 8a and 8b which mesh with one another when they are closed.

In use, the two shells 2a and 2b are first opened as shown in FIG. 1, and then they are fitted on the ball portion 9' of ball stud 9 such that the halves of the ball portion are received in the respective recesses. The two shells 2a and 2b are then abutted face to face by bending the hinges 5a and 5b at the ends of the connecting piece 4. At this time, the projections 7a provided on the shell 2a are inserted into the recesses 7b provided on the side of the other shell 2b, whereby the two shells are positioned relative to each other. Also, the pawls 8a and 8b on the two shells are meshed with one another as shown in FIG. 4 to hold the two shells in the joined state. Thus, the ball portion 9' of the ball stud 9 is held for rocking in all directions in the recesses 1 of the shells.

Subsequently, to couple the ball stud 9 to a work 10, the shells 2a and 2b joined together are forcibly inserted with the connecting piece 4 first through a mounting hole 10' of the work. As a result, the mounting portions 3a and 3b are pushed and inwardly flexed by the edge of the mounting hole 10'. When the flanges 6a and 6b of the shells reach the surface of the work, stepped free end portions 3' of the mounting portions 3a and 3b are hooked on the edge of the mounting hole, and the mounting portions 3a and 3b are slightly elastically restored. Thus, the halves "A" and "B" joined together are mounted on the work by the flanges 6a and 6b and mounting portions 3a and 3b providing residual restoring forces.

In the case of the instant embodiment, the mounting hole 10' formed in the work has a circular portion, in which the shells 2a and 2b joined together are fitted, and diametrically opposed notch portions, in which the mounting portions 3a and 3b are locked in the hooked state.

Thus, when a strong force tending to pull the ball portion 9' of the ball stud out of the recesses 1 of the shells is applied with the ball joint mounted on the work, the two halves of the joint will not be detached from the work. In addition, since the two shells joined together are enclosed in the mounting hole, they will not be forced apart, but the externally applied force is withstood to reliably prevent detachment of the ball portion 9'. When the two shells 2a and 2b are joined together by bending the hinges 5a and 5b of the connecting piece 4, they are positioned with respect to each other by projections 11a and 11b projecting from their bottom and hole 4' formed in the connecting piece 4, i.e., with the projections received in the hole.

Further, while in the above embodiment the mounting portions 3a and 3b are shown to be in an anchor-like form, this is by no means limitative.

As has been described in the foregoing, according to the invention the flanges 6a and 6b of the shells project from the surface of the work, and the shells are held in the state that they are joined together in the mounting hole of the work. The ball joint according to the invention thus can be used even in a small space. Further, in case where an external force tending to pull the ball portion of the ball stud out of the recesses is applied to the ball portion, the detachment of the ball portion can be prevented because the shells joined together are enclosed in the mounting hole of the work and prevented from being forced apart.