JP3669749B2 - Ball joint - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ball joint used for an automobile suspension or the like, and particularly relates to a structure of a ball seat.
[0002]
[Prior art]
A conventional ball joint 35 shown in FIG. 8 includes a ball sheet 42 having a two-piece structure. The ball joint 35 has a socket 36 having an opening 38 formed in the lower portion thereof, and an upper ball sheet 40 formed of a hard synthetic resin in a substantially hemispherical shell shape is inserted into the socket 36 from the opening 38. The The upper hemisphere of the spherical head 6 of the stud 5 is inserted into the upper ball sheet 40, and the shaft portion 7 of the stud 5 is projected out of the socket 36 through the opening 38. Further, a lower ball sheet 41 formed in an annular shape having a flange with a hard synthetic resin is put on the lower hemisphere of the spherical head 6, and a cap 39 is put on the lower ball sheet 41. The outer edge portion of the cap 39 is applied to a stepped portion 43 formed along the opening 38 of the socket 36, and is fixed by caulking the lower edge of the opening 38 inward. At this time, the outer edge portion 44 of the lower ball sheet 41 is sandwiched between the socket 36 and the cap 39 and fixed.
[0003]
Here, as shown in FIG. 9, the convex portion 46 formed on the lower end surface of the upper ball sheet 40 fits into the concave portion 47 provided on the upper end surface of the lower ball sheet 41, thereby relatively rotating both of them. Stop is planned. Therefore, by fixing the lower ball sheet 41 with the cap 39, absolute rotation prevention of both the ball sheets 40, 41 is also achieved.
[0004]
A ball joint 50 shown in FIG. 10 includes a ball sheet 54 having a one-piece structure. The ball joint 50 includes a socket 51 having an opening 53 formed in a lower portion thereof, and a ball sheet 54 is inserted into the socket 51 from the opening 53. The ball sheet 54 is integrally formed of a hard synthetic resin so that the upper part has a substantially hemispherical shell shape and the lower part has a substantially cylindrical shape. The spherical head 6 of the stud 5 is inserted into the ball sheet 54, and the shaft portion 7 of the stud 5 is projected out of the socket 51 through the opening 53. Further, a cap 55 is put on the lower end portion of the ball sheet 54. The outer edge 57 of the cap 55 is applied to a step 56 formed along the opening 53 of the socket 51 and fixed by caulking the lower edge of the opening 53 inward. By this caulking, the lower end portion of the ball seat 54 is compressed by a predetermined tightening allowance.
[0005]
[Problems to be solved by the invention]
However, in the case of the ball sheets 40 and 41 made of the hard synthetic resin having the two-piece structure, the tightening pressure of the cap 39 that fixes the ball sheets 40 and 41 is applied to the outer edge portion 44 of the lower ball sheet 41, In 41 and the spherical head 6, the variation in component dimensions directly affected the rotational torque. Therefore, depending on the variation, there is a backlash between the spherical head 6 of the stud 5 and the ball seat 42 and the rotational torque becomes low, or the spherical head 6 of the stud 5 and the ball seat 42 are tightened and rotated. There is a problem that the torque may become extremely high and the characteristic value at the time of assembly varies.
[0006]
In the case of the hard synthetic resin ball sheet 54 having the one-piece structure, the tightening pressure of the cap 55 that fixes the ball sheet 54 is directly applied to the lower end portion of the ball sheet 54. The tightening allowance in the axial direction changed and had a great influence on the rotational torque of the stud 5. That is, since the ball seat 54 made of a hard synthetic resin has a high elastic coefficient and a large rate of change in the preload with respect to the elastic deformation amount, the dimensional variation greatly affects the characteristic value of the rotational torque at the time of assembly. There was a problem that caused
[0007]
Further, the ball sheets 40, 41, and 54 of the one-piece structure and the two-piece structure are distorted by slight wear and plastic deformation that cannot be avoided during use, and the spherical head 6 The preload between the stud 5 and the ball seats 40, 41, when the rotational torque of the stud 5 is extremely reduced or severely deteriorated after a short period of use. There was a case where a backlash between the two and 54 occurred. When the ball joints 35 and 50 are in such a state, when these ball joints 35 and 50 are used, for example, in an automobile suspension, there is a possibility that excellent riding comfort cannot be secured.
[0008]
An object of the present invention is to solve the above-mentioned problems, eliminate variations in characteristic values such as rotational torque between the stud and the ball seat during assembly, and assemble the characteristic values even when receiving external input over a long period of time. An object of the present invention is to provide a ball joint that can be maintained in the state of time and can ensure excellent riding comfort for a long period of time when the ball joint is used, for example, in an automobile suspension.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a ball joint according to the present invention includes a bottomed container-like socket having an opening, a spherical head disposed in the socket, and a shaft protruding from the opening to the outside of the socket. A ball seat interposed between the socket and the spherical head, and a cap for compressing the mouth of the ball sheet in the axial direction. In the ball joint, the ball sheet is provided with a slit extending in the axial direction from the mouth, and a main sheet made of a hard synthetic resin that wraps the upper and lower hemispheres of the spherical head, and a mouth of the main sheet A soft synthetic resin backup sheet that is arranged on the outer periphery of the portion and is compressed with a tightening margin by the cap so as to bite into the slit and integrate with the main sheet It was.
[0010]
Here, the “axial direction” means the direction of the central axis of the ball seat. Examples of the “hard synthetic resin” include polyacetal. Examples of the “soft synthetic resin” include polyester elastomer and polyurethane. The “tightening allowance” refers to an amount of the backup sheet that is elastically compressed and deformed by being pressed by the cap.
[0011]
The main sheet of the present invention may be provided with a protrusion that bites into the backup sheet on the outer peripheral surface of the mouth. Examples of the “protrusions” include ridges and protrusions. Further, a recess such as a groove or a hole can be provided instead of the “projection”.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.
First, FIGS. 1-4 has shown the ball joint of 1st embodiment. The socket 2 of the ball joint 1 of the present embodiment is provided with a spherical hollow storage chamber 3, which has a bottomed container shape. A grease reservoir 12 is recessed in the top of the spherical shape of the storage chamber 3. An opening 4 is formed in the lower portion of the storage chamber 3, and a stepped portion 21 is provided around the opening 4. A cap 20 for holding the spherical head 6 in the storage chamber 3 is applied to the stepped portion 21 via a ball sheet 10 described later, and is fixed by caulking the lower edge of the opening 4 inward. Yes.
[0013]
The stud 5 is integrally formed from a spherical head 6 disposed in the storage chamber 3 and a shaft portion 7 protruding downward from the storage chamber 3.
[0014]
Between the storage chamber 3 and the spherical head 6, a ball sheet 10 composed of a main sheet 8 made of polyacetal as a hard synthetic resin and a backup sheet 9 made of a polyester elastomer as a soft synthetic resin is placed on the stud 5. The spherical head 6 is interposed.
[0015]
The main sheet 8 is formed in a substantially spherical shell shape in which a circular hole 13 matching the opening of the grease reservoir 12 is provided in the upper part, and a mouth part 14 for inserting the spherical head 6 of the stud 5 is provided in the lower part. ing. Below the equator portion 11 of the main sheet 8 is an outer peripheral surface 26 on which the backup sheet 9 is arranged on the outer side, and the thickness of the main sheet 8 is reduced. As shown in FIG. 2, slits 25, 25... Extending from the mouth portion 14 in the axial direction are provided on the outer peripheral surface 26.
[0016]
The backup sheet 9 is formed in an annular shape and disposed on the outer peripheral surface 26. The backup sheet 9 protrudes from the step portion 21 before being pressed by the cap 20, and is pressed in the axial direction by the cap 20, as shown by a two-dot chain line in FIG. When this occurs, a fastening allowance A is provided that is elastically compressed and deformed to the same level as the stepped portion 21. That is, when the bottom portion 22 of the backup sheet 9 is pressed by the cap 20, the tightening allowance A is elastically compressed and deformed, and the outer peripheral surface 26 of the main sheet is pressed inward by the elastic force, whereby the spherical head 6 Appropriate preload is applied.
[0017]
At this time, as shown in FIG. 4, the soft synthetic resin backup sheet 9 having a low elastic coefficient bites into the slit 25 of the main sheet 8 made of a hard synthetic resin having a high elastic coefficient. 9 is integrated.
[0018]
In addition, a dust cover 16 that covers the vicinity of the opening 4 of the socket 2 is fixed to the annular mounting groove 15 formed on the outer periphery of the socket 2 by an annular fitting 17 that is insert-molded at the upper end of the dust cover 16. The sliding seal portion 18 formed integrally with the lower end portion of the dust cover 16 is slidably attached to a flange-shaped plate 19 fixed to the outer periphery of the shaft portion 7.
[0019]
The ball joint 1 configured as described above has the following operations and effects. That is, a large load component in the axial direction of the stud 5 due to external input from the suspension generated when the ball joint 1 is used and in a direction perpendicular thereto is a portion mainly above the equator portion 11 of the main seat 8 in contact with the spherical head 6. Receive. Since the main sheet 8 is formed of polyacetal, it is not greatly deformed or broken by the load component.
[0020]
As described above, when the bottom portion 22 of the backup sheet 9 is pressed by the cap 20, the fastening allowance A is elastically compressed and deformed, and the outer peripheral surface 26 of the main sheet is pressed inward by the elastic force. An appropriate preload is applied to the spherical head 6. Here, since the backup sheet 9 is formed of a polyester elastomer, the elastic modulus is low, and the change rate of the preload with respect to the elastic deformation amount is small, so that the tightening allowance A can be increased. Further, since the backup sheet 9 bites into the slit 25 of the main sheet 8, the tightening allowance A can be further increased. As a result, as described in [0006], the conventional hard synthetic resin ball sheet 54 has a high elastic coefficient. Therefore, as shown by a broken line in FIG. Thus, the variation in the tightening allowance greatly affects the rotational torque. In the ball seat 10 of the present invention, as shown by the solid line in FIG. 5, the variation range of the rotational torque is a. Can be reduced. That is, variations in part dimensions such as a tightening allowance during assembly are absorbed, and characteristics such as rotational torque during assembly are stabilized.
[0021]
Furthermore, since the tightening allowance A can be increased as described above, even if the main seat 8 is slightly worn during use, the preload due to the tightening allowance A hardly changes. In addition, the backup sheet 9 has a large elastic deformation range, and as described above, since a large load component is not applied below the equator portion of the main sheet, it may be plastically deformed beyond the elastic deformation range. There ’s nothing, no hesitation. Therefore, even if external input is received over a long period of time, an appropriate preload between the stud 5 and the ball seat 10 can be maintained, and of course, no play occurs between the stud 5 and the ball seat 10. .
[0022]
Further, as described above, the backup sheet 9 bites into the slit 25 of the main sheet 8 at the time of assembly, whereby the backup sheet 9 and the main sheet 8 are integrated, and the relative detent effect of the ball sheet 10 is enhanced.
[0023]
As described above, according to the ball joint of the present embodiment, the necessary function as the ball joint 1 is synergistically improved by the ball sheet 10 including the two sheets 8 and 9 having different properties. The excellent ride comfort of the initial automobile can be ensured over a long period of time.
[0024]
Next, FIG. 6 shows the main seat 27 of the ball seat 30 used for the ball joint of the second embodiment. The main sheet 27 is different from the first example in that protrusions 28, 28... Are provided on the outer peripheral surface 29 of the mouth portion 14, and the same configuration as the first embodiment is common to the drawings. The description is abbreviate | omitted and attached | subjected.
[0025]
In the second embodiment, as shown in FIG. 7, since the backup sheet 9 whose bottom 22 is pressed by the cap 20 is made of a soft synthetic resin having a low elastic coefficient, the protrusion 28 of the main sheet 27 made of hard synthetic resin. As a result, the main sheet 27 and the backup sheet 9 are integrated. For this reason, the anti-rotation effect of the ball sheet 30 is further enhanced.
[0026]
In addition, this invention is not limited to the structure of the said embodiment, For example, as follows, it can also be changed and embodied suitably in the range which does not deviate from the meaning of invention.
(1) In 1st embodiment or 2nd embodiment, extending a slit above the equator part of a main sheet.
(2) In the first embodiment or the second embodiment, the thickness of the outer peripheral surface of the mouth portion of the main sheet is not reduced, but is the same as the thickness of the upper portion of the main sheet.
(3) In the second embodiment, the protrusion illustrated as the protrusion is a protrusion. In addition, a recess such as a groove or hole should be provided instead of the protrusion.
[0027]
【The invention's effect】
Since the ball joint according to the present invention is configured as described above, the characteristics of the rotational torque between the stud and the ball seat during assembly are eliminated, and the characteristics can be obtained even when external input is received over a long period of time. The value can be maintained as it is at the time of assembly, and when the ball joint is used, for example, in an automobile suspension, an excellent effect that an excellent ride comfort in the initial use can be secured over a long period of time. Play.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a ball joint according to a first embodiment embodying the present invention.
FIG. 2 is a front view of a main seat of the ball joint.
3 is an enlarged cross-sectional view showing a main part P in FIG. 1. FIG.
4 is a cross-sectional view taken along the line IV-IV in FIG. 3;
FIG. 5 is a graph showing the relationship between the tightening allowance of the ball joint and the rotational torque.
FIG. 6 is a front view of a main seat of a ball joint according to a second embodiment embodying the present invention.
FIG. 7 is a cross-sectional view of outer peripheral surfaces of the main sheet and a backup sheet.
FIG. 8 is a cross-sectional view of a conventional ball joint.
FIG. 9 is a perspective view of a ball seat of the ball joint.
FIG. 10 is a cross-sectional view of a conventional ball joint.
[Explanation of symbols]
1 Ball joint 2 Socket 5 Stud 6 Spherical head 8 Main sheet 9 Backup sheet 10 Ball sheet 14 Portion 20 Cap 25 Slit 28 Projection 29 Outer surface

Claims (2)

There is a bottomed container-shaped socket having an opening, a stud having a spherical head disposed in the socket, a shaft protruding from the opening to the outside of the socket, and a mouth through which the shaft is inserted. In a ball joint comprising a ball seat interposed between the socket and the spherical head, and a cap for compressing the mouth portion of the ball seat in the axial direction,
The ball seat is
A main sheet made of a hard synthetic resin provided with a slit extending in the axial direction from the mouth, and enclosing the upper and lower hemispheres of the spherical head;
It is arranged on the outer periphery of the mouth portion of the main sheet, and is composed of a soft synthetic resin backup sheet that bites into the slit and is integrated with the main sheet by being compressed with a tightening margin by the cap. Ball joint to be. The ball joint according to claim 1, wherein a protrusion that bites into the backup sheet is provided on an outer peripheral surface of the mouth portion of the main sheet.

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