JPH055291Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a ball joint in which the spherical head of a ball stud is rotatably fitted into the fitting hole of a socket via a ball seat, and in particular, This invention relates to improving the lubricity between the head and the ball seat.

Prior Art A ball stud having a shaft and a spherical head;
On the other hand, the inner wall surface on the opening side is a curved surface having approximately the same curvature as the spherical head, and the socket has a fitting hole for accommodating the spherical head with the shaft protruding from the opening. A ball joint in which the spherical head of the stud is slidably fitted into the fitting hole of the socket, thereby connecting the ball stud and the socket so that they can rotate freely in all directions relative to each other, For example, it is often used in the connection between the car body and the lower arm of a car.
And, as a type of ball joint like this,
A resin ball sheet is interposed between the spherical head and the inner wall surface of the fitting hole, the spherical head is wrapped in a band shape, and the spherical head is slid between the spherical head and the ball sheet. Some devices are designed to stabilize the friction torque by preventing friction on the inner wall surface of the fitting hole or fitting hole.

As such a ball seat, for example,
As disclosed in Japanese Patent No. 44980, the end of the ball stud located on the shaft side has a cylindrical shape in the free state, but it is different from the spherical head and the inner wall surface of the fitting hole. Conventionally, devices have been used that are deformed along the spherical head by being interposed between them, and wrap the spherical head in a band shape. Since one end has a cylindrical shape in the free state, it is easier to cut out from the mold and assemble into the ball joint than a ball seat, which has the same shape as the spherical head even in the free state. It has the advantage of being easy to attach.

Problems to be Solved by the Invention However, in the conventional ball seat described above, the lubricating oil reservoir is only provided in an annular shape at the center of the spherical head, so the ball seat and the spherical head are not necessarily connected. It cannot be said that the space between the two is sufficiently lubricated, and there is a risk that the friction torque between the two may fluctuate or seizure may occur due to insufficient lubrication. On the other hand, as described in, for example, Japanese Utility Model Application Publication No. 59-88511, a portion of the inner wall surface of the ball seat that makes sliding contact with the spherical head is connected from the top side of the spherical head to the shaft side. It is conceivable to provide multiple grooves to guide the lubricant, but even in that case, the portion of the groove on the shaft side may be damaged due to the deformation of the ball seat when it is assembled to the ball joint. There was a problem in that the lubricity was impaired due to crushing, and the surface pressure locally increased, making it impossible to obtain uniform sliding performance.

Further, as described in Japanese Patent Application Laid-Open No. 100548/1983, a plurality of cut portions are provided at the end of the shaft portion that is deformed along the shape of the spherical head, and the cut portions are connected to the cut portions. It is also possible to form multiple grease lubrication grooves, but in this case, the overall rigidity may decrease due to division at the cut portion, and stress concentration may occur at the boundary between the cut portion and the lubrication groove. Due to this, the durability of the ball seat was significantly reduced, and there was also a problem of grease leaking from the cut portions.

Means for Solving the Problems The present invention has been made to solve the above problems, and its gist is that, as mentioned above, the ball seat is located on the shaft side of the ball stud. A ball whose end portion has a cylindrical shape in a free state, but is deformed along the spherical head by being interposed between the spherical head and the inner wall surface of the fitting hole. At the joint, a plurality of grooves communicating from the top side of the spherical head to the shaft side are provided in a portion of the inner wall surface of the ball seat that makes sliding contact with the spherical head, and the grooves are connected to the shaft side in a free state. The width of the groove is made wider as it approaches the shaft, and a tapered surface is provided on the outer circumferential side of the end of the ball seat on the shaft side, the diameter of which decreases toward the edge.

Function and Effect of the Invention In this way, the ball seat is interposed between the spherical head and the inner wall surface of the fitting hole, and the end of the ball seat on the shaft side is deformed along the spherical head. Even in this state, the portion of the groove provided on the inner wall surface of the ball seat on the shaft portion side is not crushed. Therefore, by introducing the lubricant into the groove, the space between the spherical head and the ball seat is well lubricated, and fluctuations in friction torque between the two and seizure due to poor lubrication are prevented. . In particular, since this groove is widened only on the shaft side, the strength and rigidity of the ball seat is better compared to the case where the groove width is widened over the entire groove or a cut section is provided. It is maintained to improve durability, and
There are no problems with grease coming out.

In addition, the tapered surface is provided so that the wall thickness of the end on the shaft side is made thinner as it approaches the edge, and as mentioned above, the groove width on the shaft side is widened, so the end is narrowed. In this situation, the contact pressure between the spherical head and the spherical head is prevented from increasing locally, and together with the improvement of lubrication performance, fluctuations and seizure of the friction torque are more effectively prevented, and the friction torque is almost uniform. Sliding performance can be obtained.

Furthermore, although such ball seats are generally integrally molded, a tapered surface is provided on the outer peripheral side at the end of the shaft side of the groove, that is, the side that forms a cylindrical shape in the free state, and the groove width of the groove is By gradually increasing the width, there is an advantage that the work of cutting out the mold from the mold becomes easier.

The width of the groove on the shaft side of the groove is preferably such that the groove width is approximately constant in the deformed state so that the ball seat will not be completely crushed even if it is deformed along the spherical head. The closer you get to the shaft, the wider it becomes.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

In FIG. 1, 10 indicates a shaft portion 12 and a spherical head portion 14.
The spherical head 14 is fitted into the fitting hole 18 of the socket 16 via a ball seat 20 so as to be rotatable in all directions. The inner wall surface 24 on the one opening 22 side of the fitting hole 18 is a spherical surface with approximately the same curvature as the spherical head 14, and the spherical head 14 is seated on the inner wall surface 24 with the ball seat 20 sandwiched therebetween. ing. Further, the shaft portion 12 projects outward from the opening 22 and is fixed to the body of an automobile (not shown), and a dust cover 26 is provided between the shaft portion 12 and the socket 16. Opening 2
It covers 2.

The ball seat 20 is integrally molded from a hard resin material such as polyacetal, and is interposed between the spherical head 14 and the fitting hole 18 so as to wrap around the spherical head 14 in a band shape.
End portion 28 of this ball seat 20 on the shaft portion 12 side
has a cylindrical shape in a free state as shown in FIG. 2, while the other end side of the inner wall surface 30 is a spherical surface with approximately the same curvature as the spherical head 14. Further, in the inner wall surface 30 of the ball seat 20 in its free state, four grooves 32 are provided at equal intervals in the circumferential direction in the axial direction from the end 28 side, and the end 28 of the grooves 32 The side portions are formed into wide portions 34 in which the groove width becomes tapered toward the edge. On the other hand, on the outer peripheral side of the end portion 28, there is a tapered surface 29 whose diameter becomes smaller toward the end edge.
The wall thickness becomes thinner as it gets closer to the edge. The ball seat 20 is interposed between the spherical head 14 and the fitting hole 18, so that the end 28 side portion of the ball seat 20 is interposed between the spherical head 14 and the fitting hole 18.
The groove 32 is narrowed along the spherical head 14 to reach the state shown in FIG. That is, the groove 32 has a length dimension sufficient to communicate from the top side of the spherical head 14 to the shaft 12 side at the portion where the inner wall surface 30 makes sliding contact with the spherical head 14 in such a mounted state. Moreover, the wide portion 34 is made wide enough not to be completely crushed despite the deformation due to such narrowing. Note that the dimensions of the wide portion 34 vary depending on the size of the ball seat 20, etc., but for example, when the groove width a of the groove 32 is 1.8 mm,
It is appropriate that the groove width b of the opening is set to 3.6 mm, which is twice that width, and the taper length c is further set to about 7 mm, which is about twice the groove width b.

In addition, a tapered surface 29 is provided on the outer peripheral side of the end portion 28, and the wall becomes thinner as it approaches the edge. , and the spherical head 14 is effectively prevented from becoming locally high, and the above-mentioned narrowing down is performed smoothly.

On the other hand, a press plate 36 is fixed to the other opening of the fitting hole 18, and the press plate 36 holds the ball seat 20 in a state where it wraps around the spherical head 14 in a band shape. Relative displacement (rattling) between the ball stud 10 and the socket 16 is prevented. Further, a predetermined lubricant such as grease is filled between the holding plate 36, the dust cover 26, and the spherical head 14, and the inside of the groove 32. The lubricant provides lubrication between the wall surface 30 and the wall surface 30. Note that the socket 16 is fixed to a lower arm of an automobile (not shown) via a mounting portion 38.

In such a ball joint, the groove 32 provided on the inner wall surface 30 of the ball seat 20
Even in the installed state shown in FIG. 1, the grooves 32 are maintained in a communicating state without being crushed.
By introducing lubricant into the spherical head 14
The space between the ball seat 20 and the ball seat 20 is well lubricated, and fluctuations in friction torque and seizure are prevented. Further, the groove width a of the groove 32 is relatively narrow, and only the groove width on the end portion 28 side that is deformed in the installed state is widened, so the strength and rigidity of the ball seat 20 is increased by providing the groove 32. not be damaged,
Compared to the case where the groove width is widened or cut across the entire groove 32, the durability of the ball seat 20 is improved and there are no problems such as grease coming out.

Further, the end portion 28 on the side of the shaft portion 12 is provided with a tapered surface 29 on the outer peripheral side, so that the wall thickness becomes thinner as it approaches the end portion, and a wide portion 34 is provided so that the groove width of the groove 32 is tapered. Since the end portion 28 is widened, even when the end portion 28 is narrowed down, the contact pressure between the end portion 28 and the spherical head 14 is prevented from increasing locally.
Therefore, together with improved lubricity, fluctuations in friction torque and seizure of the ball seat 20 are more effectively prevented, and substantially uniform sliding performance can be obtained.

On the other hand, such a ball seat 20 is generally integrally molded by injection molding or the like, and in this way, a tapered surface 29 is provided on the outer peripheral side of the end portion 28, and the groove 32 on the end portion 28 side is tapered and widened. This also has the advantage of facilitating the work of removing the mold from the mold.

Although one embodiment of the present invention has been described above in detail based on the drawings, the present invention can also be implemented in other embodiments.

For example, in the above embodiment, the present invention was applied to a ball joint inserted between the body and the lower arm of a car, but the present invention can also be applied to other parts of a car or to something other than a car. The same can be applied to ball joints.

Furthermore, although four grooves 32 are provided in the above embodiment, the number of grooves 32 is greater than the number of grooves 32 provided in the ball seat 20.
They may be set as appropriate depending on the size of the spacer, and they do not necessarily need to be provided at equal intervals in the circumferential direction.

Although no other examples are given, the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view showing a ball joint that is an embodiment of the present invention. 2 is a longitudinal sectional view showing the ball seat of the ball joint of FIG. 1. FIG. 10...Ball stud, 12...Shaft portion, 14
... Spherical head, 16 ... Socket, 18 ... Fitting hole, 20 ... Ball seat, 22 ... Opening, 2
4... Inner wall surface, 28... End, 29... Tapered surface, 30... Inner wall surface, 32... Groove.

Claims (1)

[Claims for Utility Model Registration] A ball stud having a shaft portion and a spherical head;
an inner wall surface on one opening side is a curved surface having approximately the same curvature as the spherical head, and a socket having a fitting hole for accommodating the spherical head with the shaft protruding from the opening; A ball seat is provided between the spherical head and the inner wall surface of the fitting hole to wrap the spherical head in a band shape, and an end of the ball seat on the shaft side is in a free state. In a ball joint of the type that has a cylindrical shape and is deformed along the spherical head by being interposed between the spherical head and an inner wall surface of the fitting hole, the ball seat A plurality of grooves communicating from the top side of the spherical head to the shank side are provided in a portion of the inner wall surface of the spherical head that makes sliding contact with the spherical head, and the groove width of the grooves on the shank side in a free state is set as above. What is claimed is: 1. A ball joint, characterized in that the diameter of the ball seat increases as it approaches the shaft, and the diameter decreases toward the edge of the ball seat on the outer peripheral side of the end of the ball seat on the shaft side.