JPH0557429U - Ball joint - Google Patents

Abstract

(57) [Abstract] [Purpose] The preset load of the ball joint that holds the ball stud 1 through the upper bearing 6 and the lower bearing 7 by the casing 5 and the cover 8 does not change significantly due to dimensional errors of the components. At the same time, the upper bearing 6 is prevented from being damaged when a large axial load is applied. A lower bearing 7 is formed of a main part 7a having a large spring constant and a sub-part 7b having a small spring constant, and when each part is assembled and a preset load is applied, a space between the main part 7 and a cover 8 is provided. The gap 11 is interposed.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The ball joint of the present invention is incorporated into a suspension mechanism that connects a vehicle wheel and a vehicle body, and is used to displaceably connect links.

[0002]

[Prior Art]

 FIG. 5 is a vertical cross-sectional view of a conventionally used ball joint of this type. A ball stud 1 is formed with a screw portion 2, a taper shaft portion 3, and a ball portion 4 from the upper end (upper and lower sides depend on the drawing; the same applies hereinafter). A casing 5 surrounds the ball portion 4, and an upper bearing 6 is interposed between the casing and the ball portion 4. 7 is a lower bearing that supports the lower surface of the ball portion 4, 8 is a cover that is screwed to the lower portion of the casing 5 and that supports the upper bearing 6 and the lower bearing 7, and 9 closes the gap between the upper end of the casing 5 and the shaft portion 3. Flexible boots. A hole 10 is provided in the center of the lower bearing 7 to retain grease, and the space between the ball portion 4 and both bearings 6 and 7 is lubricated. Both bearings 6 and 7 are made of an elastic material such as nylon or Delrin, and have a vertical cross section formed into a circle as shown in FIG.

When one of the links of the suspension mechanism is connected to the screw part 2 and the casing 5 is connected to the other link, both links are connected so as to be displaceable in all the lateral directions of the tapered shaft part 3. ..

In the conventional ball joint configured as described above, a load is applied to the tapered shaft portion 3 in the axial downward direction. In this case, mainly the lower bearing 7 is elastically compressed and displaced, and the elastic force supports the axial load. The relationship between the magnitude of the supporting force in the axial direction and the displacement of the lower bearing 7 in the axial direction has a linear shape as shown by line A in FIG. 3 described later.

A preset load is applied to the lower bearing 7 by assembling the cover 8 into the casing 5 during assembly. The preset load has the following properties.

(1) When the preset load of the lower bearing 7 is increased, the swing torque of the ball stud 1 is increased, which adds resistance to the movement of the linked links. From this point of view, the smaller the preset load is, the better.

(2) When a load is applied to the ball stud 1 in the axial direction, the lower bearing 7 is elastically compressed, and the elastic bearing force determined by the spring constant thereof supports the load. From this point of view, it is preferable to increase the spring constant of the lower bearing 7 and increase the preset load. When the preset load is small, the amount of compression of the lower bearing 7 due to the axial load is large, and the displacement of the ball portion 4 is also large, so that there is a risk of damaging the upper bearing 6.

(3) Further, since the respective parts of the ball stud 1 are slightly different in size due to manufacturing errors, in order to reduce the change of the preset load at the time of assembly due to the size error, the spring of the lower bearing 7 is reduced. It is desirable that the constant is small.

[0009]

[Problems to be solved by the device]

 However, if the preset load of the lower bearing 7 is made small for the reasons (1) and (3) above, the displacement of the ball portion 4 becomes large when a large axial load is applied as described above (2), There is a risk of damaging the upper bearing 6.

[0010]

[Means for Solving the Problems]

 According to this invention, the lower bearing is formed of a main part having a large spring constant and a sub-part having a small spring constant, and a gap is provided between the main part and the cover when the sub-part is compressed and a preset load is applied. Intervening.

[0011]

[Action]

 During assembly, only the sub-part of the lower bearing, which has a small spring constant, is compressed and displaced, so even if there is a dimensional error in the component parts, the change in the elastic bearing force of the sub-part will be small and the preset load will change significantly. There is no such thing. Even if the axial load is small, only the secondary part acts to support this load. When the axial load becomes large, the gap between the main part and the cover disappears, and the main part with a large spring constant is also compressed and exerts a large supporting force with a small displacement to support it. It will not be damaged.

[0012]

【Example】

 FIG. 1 is a vertical sectional view showing an embodiment of a ball joint according to the present invention. The same parts as those of the conventional structure shown in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted.

The feature of this structure is that the lower bearing 7 abuts on the ball portion 4 and has a large-diameter circular main portion 7a having a large spring constant, and a small circular constant having a small spring constant protruding downward from the center thereof. It is formed by the sub-part 7b and the gap is provided between the cover 8 and the main part 7a at the time of assembly. That is, a recess 8a is formed in the cover 8 to accommodate the small-diameter sub-part 7b, and when the sub-part 7b is brought into contact with the bottom of the recess 8a, a gap 11 is present between the lower surface of the main part 7a and the cover 8. To do so. As the shape of the lower bearing 7, as shown in FIG. 2, an annular protruding portion having a small spring constant may be formed in the peripheral portion to serve as the sub portion 7b.

In the lower bearing thus formed, the relationship between the displacement of the lower bearing and the elastic supporting force generated by this displacement has a polygonal shape as indicated by lines B and B ′ in FIG. The line B shows the relationship between the displacement of the sub portion 7b and the supporting force, and the line B'shows the relationship between the displacement of the main portion 7a and the supporting force. The lower bearing 7 operates as follows.

(1) When assembling the ball stud, when the component parts have a dimensional error and the compression amount of the lower bearing for applying the preset load is different, the sub-part 7b having a small spring constant is used. Only the pres- sure is compressed, so the change in preset load is small and is within the allowable range.

This will be described with reference to FIG. If there is a difference in the amount of displacement of the lower bearing 7 of the two assembled ball studs due to the dimensional error of the component parts, and if one is a and the other is b, the difference between the preset loads in this case is m It becomes the size of.

The comparison with the lower bearing of the conventional ball joint (FIG. 5) is as follows. In the conventional ball joint, the relationship between the displacement of the lower bearing and the supporting force is as shown by the line A in Fig. 3, and similarly, the displacements of the two lower bearings whose displacement amounts are a and b are the same. The difference in preset load is n (n> m), and the difference in preset load becomes large for the same dimensional error of parts. In the ball joint of the present invention, since there is a gap 11 between the cover 8 and the main portion 7a, the change in the supporting force due to the deformation of the lower bearing to the extent that a preset load is applied is caused by the deformation of only the sub portion 7b. Appearing along the line B of No. 3, the main part 7a is not compressed.

(2) When a large axial load is applied to the ball stud 1, the sub portion 7b is compressed until the gap 11 is eliminated, and then the compression of the main portion 7a starts along line B'in FIG. .. Since the main portion 7a has a large spring constant, it is compressed by a small displacement of the ball portion to generate a large supporting force to support the ball portion 4. Therefore, no excessive force is applied to the upper bearing 6.

When the axial load is small and the compressive displacement of the small diameter portion 7b is not enough to eliminate the gap 11, the axial load is supported only by the supporting force generated by the sub portion 7b.

As shown in FIG. 2, when an annular sub-portion 7c having the same spring constant as the sub-portion 7b of FIG. Is also the same.

FIG. 4 shows an example in which the lower surface of the main portion 7a of the lower bearing 7 is slowly projected by a smaller amount than the sub portion 7c that annularly projects from the peripheral edge. Since the contact with the cover 8 is gradually performed, the change in the axial supporting force does not suddenly occur. That is, in FIG. 3, the straight lines B and B'are connected by the curved C line.

[0022]

[Effect of the device]

 (1) Since the lower bearing is made up of a main part with a large spring constant and a small auxiliary part, and a preset load during assembly is applied using the sub-part with a small spring constant, dimensional errors during manufacturing will not occur in each part. If so, the preset load does not change significantly for this reason.

(2) Further, when a large axial load is applied, the displacement of the ball stud 1 is suppressed by the action of the main part having a large spring constant, so that the upper bearing is not damaged. ..

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a ball joint showing an embodiment of the present invention.

FIG. 2 is a vertical sectional view showing a second example of the lower bearing of the present invention.

FIG. 3 is a diagram showing the relationship between the axial support force and the axial displacement of the lower bearing of the present invention.

FIG. 4 is a vertical cross-sectional view showing a third example of the lower bearing of the present invention.

FIG. 5 is a vertical sectional view of a conventional ball joint.

[Explanation of symbols]

 1 Ball Stud 2 Screw Part 3 Tapered Shaft Part 4 Ball Part 5 Casing 6 Upper Bearing 7 Lower Bearing 7a Main Part 7b Sub Part 7c Sub Part 8 Cover 8a Recess 9 Boot 10 Hole 11 Gap

Claims (1)

[Scope of utility model registration request] 1. A side surface of a ball portion (4) of a ball stud (1) having a screw portion (2) at a tip portion, a tapered shaft portion (3) at an intermediate portion, and a ball portion (4) at a base portion. A ball stud supported by a casing (5) via an upper bearing (6), and the lower surface of the ball portion (4) supported by a cover (8) connected to the casing (5) via a lower bearing (7). In the above, the lower bearing (7) is inserted into the main portion (7a) having a large spring constant that abuts on the ball portion and the recess (8a) of the cover (8) protruding from the main portion (7a) toward the cover (8). And a sub-part (7b) (7c) having a small spring constant, and a preset load is applied to the concave part (8) of the cover (8).
It is provided by compression of the sub-part (7b) by the bottom of a), and a gap (11) is provided between the main part (7a) and the cover (8) when a small load including a preset load is applied to the ball stud (1). ) Intervening ball joint.