JP2009210027A - Ball joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ball joint capable of reducing abrasion in a resin sheet. <P>SOLUTION: This ball joint includes: a ball stud 18 for arranging a spherical head part 23 having a spherical-like outside surface in its end part; a resin sheet for covering the outside surface of the spherical head part 23 and slidably holding the spherical head part 23; a lubricant filled between the spherical head part 23 and the resin sheet; and a housing for storing the spherical head part 23 and the resin sheet. A plurality of fine dimples 42 are formed on the whole outside surface area of the spherical head part 23. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ball joint.

Some ball joints contain a metal ball in a cylindrical housing (see, for example, Patent Document 1). A synthetic resin resin sheet is interposed between the housing and the ball. The ball slides with respect to the resin sheet.
JP 2003-262213 A

As described above, the ball slides with respect to the resin sheet. For this reason, the resin sheet may be worn and the ball may be rattled. Such rattling is one of the causes of reducing ball joint characteristics (for example, torque characteristics, silence characteristics, etc.).
Then, the objective of this invention is providing the ball joint which can reduce the abrasion of a resin sheet.

  In order to achieve the above object, the invention according to claim 1 is characterized in that a spherical head (23, 39) in which irregularities (42, 43, 45, 46) for holding a lubricant are formed on a spherical outer surface. A ball stud (18, 31) having a surface, a resin sheet (17, 30) covering the outer surface and holding the ball head slidably, and a space between the ball head and the resin sheet And a ball joint (12, 13) including the lubricant and a housing (16, 29) in which the ball head and the resin sheet are accommodated.

In this section, alphanumeric characters in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.
According to this invention, the ball head of the ball stud and the resin sheet are accommodated in the housing, and the ball head is covered with the resin sheet in the housing. The ball head is slidable with respect to the resin sheet, and a lubricant is filled between the ball head and the resin sheet. Furthermore, unevenness for holding the lubricant is formed on the outer surface of the spherical spherical head. Therefore, at least a part of the lubricant filled between the ball head and the resin sheet is held in the recess. Therefore, the lubricant is not lost between the ball head and the resin sheet, and the good lubrication state of the ball head with respect to the resin sheet is reliably maintained. Thereby, wear of the resin sheet caused by sliding of the ball head is reduced.

The unevenness may be formed on a part of the outer surface of the ball head, or may be formed on the entire outer surface. By forming the unevenness on the entire outer surface of the sphere head, the lubricant can be held on the entire outer surface of the sphere head. Thereby, the lubricity of the ball head can be improved.
The invention according to claim 2 is the ball joint according to claim 1, wherein the unevenness includes a plurality of dimples (42) formed in the entire area of the outer surface.

  According to the present invention, the lubricant can be held in the plurality of dimples. Thereby, the lubricity of the ball head with respect to the resin sheet is ensured. Therefore, wear of the resin sheet caused by sliding of the ball head is reduced. Furthermore, since the plurality of dimples are formed over the entire outer surface of the ball head, the lubricity of the ball head is further improved. Further, since the surface area of the ball head is increased by forming a plurality of dimples, more lubricant can be held on the outer surface of the ball head.

The invention according to claim 3 is the ball joint according to claim 1, wherein the unevenness includes a plurality of concave grooves (45) formed over the entire outer surface and extending along the outer surface.
According to this invention, the lubricant can be held in the plurality of concave grooves. Thereby, the lubricity of the ball head with respect to the resin sheet is ensured. Therefore, wear of the resin sheet caused by sliding of the ball head is reduced. Furthermore, since the plurality of concave grooves are formed in the entire outer surface of the ball head, the lubricity of the ball head is further improved. In addition, since the plurality of concave grooves can function as dynamic pressure grooves, the spherical head can be brought into non-contact with the resin sheet when the spherical head slides with respect to the resin sheet. Thereby, abrasion of the resin sheet caused by sliding of the ball head can be further reduced.

Embodiments of the present invention will be specifically described below with reference to the drawings.
FIG. 1 is a schematic diagram illustrating a schematic configuration of a steering apparatus 1 including a ball joint according to an embodiment of the present invention. The steering device 1 includes a steering wheel 2 as a steering member and a rack and pinion mechanism 3 as a turning mechanism for turning steered wheels (not shown).

The steering wheel 2 is connected to the rack and pinion mechanism 3 via a steering shaft 4 and an intermediate shaft 5. The rotation of the steering wheel 2 is transmitted to the rack and pinion mechanism 3 via the steering shaft 4 and the intermediate shaft 5.
The rack and pinion mechanism 3 includes a pinion shaft 6 and a rack shaft 7. The pinion shaft 6 includes a shaft portion 8 connected to the intermediate shaft 5 and a pinion 9 connected to the tip of the shaft portion 8. The rotation of the steering wheel 2 is transmitted to the pinion shaft 6 via the steering shaft 4 and the intermediate shaft 5.

The rack shaft 7 extends along the left-right direction of the vehicle. A rack 10 is formed on the rack shaft 7. The pinion 9 and the rack 10 are meshed with each other. The rotation of the pinion shaft 6 is converted into an axial movement of the rack shaft 7 by the rack 10 and the pinion 9.
The rack shaft 7 is inserted into a cylindrical housing 11. Both end portions of the rack shaft 7 protrude from the housing 11. One end of a tie rod 14 is connected to each end of the rack shaft 7 via an inner ball joint 12. An outer ball joint 13 is provided at the other end of the tie rod 14 (so-called tie rod end). Although not shown, the steered wheels are connected to the outer ball joint 13 via a knuckle arm.

  A cylindrical rack boot 15 is disposed at each end of the housing 11. One end of each rack boot 15 is fitted around the end of the housing 11 and is fixed to the end. Further, the other end of each rack boot 15 is externally fitted to the tie rod 14 and is fixed to the tie rod 14. The end of the housing 11 and the inner ball joint 12 are covered with a corresponding rack boot 15. The rack boot 15 prevents foreign matters such as water and dust from entering the housing 11 and the inner ball joint 12.

  In the steering operation (rotation operation), as described above, the rotation of the steering wheel 2 is transmitted to the pinion shaft 6 by the steering shaft 4 and the intermediate shaft 5, and the rotation of the pinion 9 is moved in the axial direction of the rack shaft 7 through the rack 10. Converted. The axial movement of the rack shaft 7 at that time is transmitted to the tie rod 14 via the inner ball joint 12, and the movement of the tie rod 14 is further transmitted to the knuckle arm via the outer ball joint 13.

FIG. 2 is a cross-sectional view of a part of the steering device 1 including the inner ball joint 12 and the outer ball joint 13.
The inner ball joint 12 includes a housing 16 connected to the end of the rack shaft 7, and a resin sheet 17 and a ball stud 18 held by the housing 16. The housing 16 includes a holding portion 19 that holds the resin sheet 17 and the ball stud 18, and a connecting portion 20 that is connected to an end portion of the rack shaft 7. The holding part 19 has a cylindrical shape with one end sealed, and has an opening. The holding part 19 has an outer diameter near the opening that is smaller than the other part. The resin sheet 17 has a cup shape and includes a peripheral wall portion 21 and a bottom portion 22. The resin sheet 17 is disposed such that the bottom portion 22 is positioned at the bottom of the holding portion 19.

  The ball stud 18 is integrally formed with a spherical head 23 having a spherical outer surface and a rod 24 extending so as to protrude from the spherical head 23. The spherical head 23 is covered with the resin sheet 17 in the holding part 19, and the rod 24 protrudes from the holding part 19. A part of the tie rod 14 is constituted by a ball stud 18. That is, the tie rod 14 includes a ball stud 18 and a connecting shaft 25 connected to the rod 24 of the ball stud 18.

  A male screw portion 26 is formed at the tip portion (right end portion in FIG. 2) of the rod 24. The male screw portion 26 is screwed into a female screw hole 27 formed in the connecting shaft 25. The male screw portion 26 is screwed into the female screw hole 27, whereby the connecting shaft 25 is coaxially connected to the ball stud 18. A lock nut 28 is screwed into the male screw portion 26. The ball stud 18 and the connecting shaft 25 are fixed to each other by a lock nut 28. The screwing amount of the male screw portion 26 with respect to the female screw hole 27 is adjusted by a lock nut 28. The toe angle of the steered wheel can be adjusted by adjusting the screwing amount of the male screw portion 26 into the female screw hole 27.

  The ball head 23 is held so as to be wrapped in the holding portion 19 via the resin sheet 17. The inner peripheral surface of the resin sheet 17 has a shape along the outer surface of the ball head 23. The ball head 23 is slidable with respect to the resin sheet 17. A lubricant such as grease is filled between the resin sheet 17 and the ball head 23. The ball stud 18 can swing with respect to the housing 16 with the ball head 23 as a fulcrum. Therefore, the movement of the rack shaft 7 (see FIG. 1) in the axial direction is not transmitted linearly in the axial direction to the tie rod 14, but is transmitted in the angular direction in which the inner ball joint 12 swings.

  On the other hand, the outer ball joint 13 includes a housing 29 and a resin sheet 30 and a ball stud 31 held by the housing 29. The housing 29 includes a cylindrical member 32 in which the resin sheet 30 is disposed, and a closing plate 33 fixed to the one end so as to close one end (the lower end in FIG. 2) of the cylindrical member 32. The cylindrical member 32 is integrally formed at the distal end portion of the connecting shaft 25, for example.

  The resin sheet 30 includes a cup-shaped first sheet 34 and a plate-shaped second sheet 35. The first sheet 34 is integrally provided with a peripheral wall portion 36 and a bottom portion 37. The first sheet 34 is disposed such that the peripheral wall portion 36 is along the inner peripheral surface of the cylindrical member 32. The second sheet 35 is interposed between the bottom 37 of the first sheet 34 and the closing plate 33. The resin sheet 30 is held between an annular flange 38 projecting inward from the other end (upper end in FIG. 2) of the cylindrical member 32 and the closing plate 33.

  The ball stud 31 is integrally formed with a spherical head 39 having a spherical outer surface and a rod 40 protruding upward from the spherical head 39. The spherical head 39 is covered with the first sheet 34 in the cylindrical member 32, and the rod 40 protrudes from the cylindrical member 32. The spherical head 39 is held by the housing 29 via the first sheet 34. That is, the ball stud 31 is held by the housing 29 via the first seat 34.

  The inner peripheral surface of the first sheet 34 is shaped along the outer surface of the ball head 39. The spherical head 39 is slidable with respect to the resin sheet 30. A lubricant such as grease is filled between the first sheet 34 and the ball head 39. The ball stud 31 can swing with respect to the housing 29 with the ball head 39 as a fulcrum. Further, the ball stud 31 is rotatable around the central axis of the rod 40. The outer ball joint 13 transmits the movement of the tie rod 14 to the knuckle arm in the swinging angular direction.

  A cylindrical cover 41 is attached to the housing 29 and the ball stud 31. One end of the cover 41 is fitted around the end of the cylindrical member 32 and is fixed to the end. The other end of the cover 41 is externally fitted to the rod 40 and is fixed to the rod 40. An end of the cylindrical member 32 and a part of the rod 40 are covered with a cover 41. The cover 41 prevents foreign matters such as water and dust from entering the outer ball joint 13.

Thus, the ball joint according to the present invention can be used as the inner ball joint 12 and the outer ball joint 13 of the steering device 1. Next, a specific configuration of the ball joint according to this embodiment will be described.
FIG. 3 is an enlarged view of a part of the ball stud 18 including the ball head 23. 4 is an enlarged view of the ball head 23, and FIG. 5 is a cross-sectional view of the dimple 42 formed on the ball head 23. As shown in FIG. FIG. 6 is a schematic diagram for explaining an example of a method for processing a plurality of dimples 42.

  In the following, with reference to FIGS. 3 to 6, the surface shape of the ball head 23 of the ball stud 18 provided in the inner ball joint 12 and a method of processing the plurality of dimples 42 formed on the ball head 23. Will be described. Although description of the ball stud 31 of the outer ball joint 13 is omitted, the ball head 39 of the ball stud 31 has the same surface shape as the ball stud 18 of the inner ball joint 12.

With reference to FIGS. 3 to 5, a plurality of dimples 42 (concaves) are formed on the entire outer surface of the ball head 23. FIG. 3 illustrates a part of the plurality of dimples 42. A portion where the dimple 42 is not formed on the outer surface of the spherical head 23 is a protrusion 43. As shown in FIG. 5, the dimples 42 and the protrusions 43 are smoothly connected.
Each dimple 42 is, for example, a circle having a diameter of about several micrometers to several millimeters. The depth of each dimple 42 is, for example, about several tens of micrometers. That is, a plurality of fine irregularities are formed on the entire outer surface of the ball head 23, and the outer surface of the ball head 23 has a matte shape. By forming a plurality of dimples 42 on the spherical head 23, the surface area of the spherical head 23 is increased.

  At least a part of the lubricant filled between the ball head 23 and the resin sheet 17 is held by the plurality of dimples 42. That is, a part of the lubricant filled between the ball head 23 and the resin sheet 17 enters each dimple 42 and is held in the dimple 42. Therefore, even if sliding of the ball head 23 with respect to the resin sheet 17 is repeated, the lubricant is not lost from between the ball head 23 and the resin sheet 17, and the ball head 23 with respect to the resin sheet 17 is good. A proper lubrication state is reliably maintained. Thereby, the abrasion of the resin sheet 17 caused by the sliding of the ball head 23 can be reduced.

Further, since the surface area of the ball head 23 is enlarged, more lubricant can be held on the outer surface of the ball head 23. Further, since the dimples 42 and the projections 43 are smoothly connected, the resin sheet 17 is scraped off by the connecting portion between the dimples 42 and the projections 43 when the ball head 23 slides with respect to the resin sheet 17. Is prevented.
Next, an example of a method for processing the plurality of dimples 42 will be described with reference to FIG.

  The plurality of dimples 42 can be formed by, for example, shot blasting. Specifically, the ball stud 18 (here, a plurality of dimples 42 are not formed, which means an intermediate body of the ball stud 18) is rotated around the central axis of the rod 24. In this state, for example, shot grains having a diameter of about 1 mm are sprayed from the shot nozzle 44 toward the spherical head 23. When shot grains are sprayed toward the spherical head 23, the shot grains collide with the spherical head 23, and the spherical head 23 is plastically deformed by the impact. Thereby, a plurality of fine dimples 42 are formed on the outer surface of the spherical head 23.

  By subjecting the spherical head 23 to shot blasting, a plurality of fine dimples 42 can be easily formed over the entire outer surface of the spherical head 23. Further, since the dimple 42 is formed by plastic deformation of the spherical head 23, the connecting portion between the dimple 42 and the projection 43 can be made smooth. Further, for example, when cutting is performed on the ball head 23 before shot blasting, the outer surface of the ball head 23 is removed by removing burrs and edge portions generated by the cutting by shot blasting. Can be smooth. Thereby, when the ball | bowl head 23 slides with respect to the resin sheet 17, it can prevent that the resin sheet 17 is scraped off by a burr | flash or an edge part.

  As described above, in the present embodiment, by providing the plurality of dimples 42 and forming the irregularities for holding the lubricant on the outer surface of the spherical head 23, the spherical head 23 with respect to the resin sheet 17 is excellent. The lubrication state can be reliably maintained. Thereby, the abrasion of the resin sheet 17 caused by the sliding of the ball head 23 can be reduced. In addition, it is only necessary to form a plurality of dimples 42 on the outer surface of the ball head 23, and other configurations included in the inner ball joint 12 can use conventional ones. It is possible to reduce the wear of the resin sheet 17 while suppressing the increase of.

Further, although a specific description of the ball stud 31 of the outer ball joint 13 has been omitted, the outer ball joint 13 also reduces the wear of the resin sheet 30 caused by the sliding of the ball head 39, as with the inner ball joint 12. In addition, an increase in manufacturing cost of the outer ball joint 13 can be suppressed.
FIG. 7 is an enlarged view of a part of a ball stud 18 according to another embodiment of the present invention. FIG. 8 is an enlarged view of the ball head 23 of the ball stud 18 according to another embodiment. 7 and 8, the same components as those shown in FIGS. 1 to 6 described above are denoted by the same reference numerals as those in FIGS. 1 to 6 and the description thereof is omitted.

The main difference between the present embodiment and the previous embodiment is that the dimples 42 are formed on the outer surface of the ball head 23 in the previous embodiment, whereas the ball head is different in this embodiment. A plurality of concave grooves 45 extending along the outer surface of the portion 23 are formed. A portion where the concave groove 45 is not formed on the outer surface of the spherical head 23 is a convex 46.
Each concave groove 45 has an annular shape extending along the circumferential direction of the spherical head 23, for example. These concave grooves 45 are arranged in parallel. The plurality of grooves 45 are arranged in a direction along the central axis of the rod 24, for example. Further, as shown in FIG. 8, the concave groove 45 and the convex 46 are smoothly connected. The width W1 of each concave groove 45 is, for example, about 1 millimeter. The depth D1 of each concave groove 45 is, for example, about 10 micrometers. That is, a plurality of fine irregularities are formed on the entire outer surface of the spherical head 23. By forming the plurality of concave grooves 45 in the spherical head 23, the surface area of the outer surface of the spherical head 23 is enlarged.

  By forming a plurality of concave grooves 45 on the outer surface of the spherical head 23, at least a part of the lubricant filled between the spherical head 23 and the resin sheet 17 is held in the concave grooves 45. Thus, it is possible to prevent the lubricant from being lost between the ball head 23 and the resin sheet 17. Thereby, the favorable lubricating state of the ball head 23 with respect to the resin sheet 17 can be reliably maintained. Therefore, the wear of the resin sheet 17 caused by the sliding of the ball head 23 can be reduced. Further, since the plurality of concave grooves 45 can function as dynamic pressure grooves, when the spherical head 23 slides with respect to the resin sheet 17, the spherical head 23 is not in contact with the resin sheet 17. Can be completely lubricated. Thereby, the abrasion of the resin sheet 17 caused by the sliding of the spherical head 23 can be further reduced.

FIG. 9 is a schematic diagram for explaining an example of a method for processing the plurality of concave grooves 45, and shows the ball stud 18 and the schematic configuration of the electrolytic processing machine 47. The electrolytic processing machine 47 includes an electrolytic bath 48 in which an electrolytic solution is stored, an electrode tool 49 partially immersed in the electrolytic solution, and a power supply 50.
The plurality of concave grooves 45 can be formed by, for example, electrolytic processing. Specifically, the electrode tool 49 is connected to the negative electrode of the power supply 50, and the ball stud 18 (here, since the plurality of concave grooves 45 are not formed means an intermediate body of the ball stud 18). Connected to the positive electrode.

Thereafter, a part of the electrode tool 49 and the ball head 23 of the ball stud 18 are immersed in the electrolytic solution in the electrolytic cell 48. The electrode tool 49 is disposed so that the machining surface 51 faces the ball head 23 in the electrolytic solution. Although not shown, a plurality of grooves corresponding to the plurality of grooves 45 are formed on the machining surface 51 of the electrode tool 49.
Next, the electrode tool 49 and the ball stud 18 are energized with the machining surface 51 of the electrode tool 49 facing the ball head 23 in the electrolytic solution. Further, the ball stud 18 is rotated around the central axis of the rod 24 while the electrode tool 49 and the ball stud 18 are energized. At this time, an electrolytic solution is interposed between the machining surface 51 of the electrode tool 49 and the ball head 23.

  When the electrode tool 49 and the ball stud 18 are energized, the outer surface of the ball head 23 is melted and a plurality of recesses corresponding to the shape of the processed surface 51 are formed on the outer surface of the ball head 23. Further, when the ball stud 18 is rotated around the central axis of the rod 24, a plurality of concave grooves extending in the circumferential direction along the outer surface are formed on the outer surface of the ball head 23. Thereby, a plurality of concave grooves 45 are formed in the entire outer surface of the ball head 23. By performing electrolytic processing, a plurality of concave grooves 45 can be easily formed in the entire outer surface of the ball head 23. Further, by performing electrolytic processing, it is possible to easily form a plurality of concave grooves 45 with high dimensional accuracy.

FIG. 10 is a diagram for explaining another example of the processing method of the plurality of concave grooves 45. In FIG. 10, (a) to (d) show a state in which resist coating, exposure, resist removal, and etching are performed on the ball head 23, respectively.
The plurality of concave grooves 45 can be formed by etching, for example. Specifically, as shown in FIG. 10A, the ball stud 18 (here, a plurality of concave grooves 45 are not formed, meaning an intermediate body of the ball stud 18) is the center of the rod 24. It is rotated around the axis. In this state, the resist solution is discharged from the resist solution supply nozzle 52 toward the spherical head 23. Thereby, the resist solution is supplied to the entire outer surface of the ball head 23 (resist application step). As a result, a resist film is formed over the entire outer surface of the ball head 23.

  Next, as shown in FIG. 10B, irradiation is performed through a mask 53 in which a pattern corresponding to the plurality of concave grooves 45 is formed in a state where the ball stud 18 is rotated around the central axis of the rod 24. Light is irradiated from the source 54 to the spherical head 23 (exposure process). Thereafter, as shown in FIG. 10C, the resist removing liquid is supplied from the resist removing liquid supply nozzle 55 to the ball head 23 in a state where the ball stud 18 is rotated around the central axis of the rod 24. Thereby, an unnecessary resist film is removed (resist removal step), and only a portion where the plurality of concave grooves 45 are formed on the outer surface of the ball head 23 is exposed.

  After the unnecessary resist film is removed, as shown in FIG. 10D, the etching solution is supplied from the etching solution supply nozzle 56 to the ball head 23 of the ball stud 18 rotated around the central axis of the rod 24. Supplied (etching process). Thereby, the outer surface of the sphere head 23 is melted by the etching liquid, and a plurality of concave grooves 45 are formed in the entire outer surface of the sphere head 23. By performing the etching process, a plurality of concave grooves 45 can be easily formed in the entire outer surface of the ball head 23. Further, by performing the etching process, it is possible to easily form the plurality of concave grooves 45 with high dimensional accuracy.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the contents of the above-described embodiments, and various modifications can be made within the scope of the claims. For example, in the above-described embodiment, the case where the present invention is applied to the inner ball joint 12 and the outer ball joint 13 has been described. The invention may be applied.

  In the above-described embodiment, the case where the device using the ball joint according to the present invention is a steering device has been described. However, the ball joint according to the present invention may be used in a device other than the steering device. Furthermore, in the above-described embodiment, the case where the steering device is a manual steering device has been described. However, the present invention is not limited to this, and the steering device may be other hydraulic or electric steering devices.

It is a mimetic diagram showing a schematic structure of a steering device provided with a ball joint concerning one embodiment of the present invention. It is a sectional view of a part of a steering device including an inner ball joint and an outer ball joint. It is an enlarged view of a part of a ball stud including a ball head. It is an enlarged view of a ball head. It is sectional drawing of the dimple formed in the bulb | ball head. It is the schematic for demonstrating an example of the processing method of several dimples. It is a partially enlarged view of a ball stud according to another embodiment of the present invention. It is an enlarged view of the ball head of a ball stud concerning the other embodiment. It is the schematic for demonstrating an example of the processing method of a some groove. It is a figure for demonstrating the other example of the processing method of a some groove.

Explanation of symbols

DESCRIPTION OF SYMBOLS 12 ... Inner ball joint (ball joint), 13 ... Outer ball joint (ball joint), 16 ... Housing, 17 ... Resin sheet, 18 ... Ball stud, 23 ... Ball head Part, 29 ... housing, 30 ... resin sheet, 31 ... ball stud, 39 ... ball head, 42 ... dimple (concave), 43 ... convex, 45 ... concave Groove, 46 ... convex

Claims (3)

A ball stud having a spherical head formed with irregularities for holding a lubricant on a spherical outer surface;
A resin sheet that covers the outer surface and slidably holds the ball head;
A lubricant filled between the ball head and the resin sheet;
A ball joint comprising: a ball head and a housing in which a resin sheet is accommodated.   The ball joint according to claim 1, wherein the unevenness includes a plurality of dimples formed over the entire area of the outer surface. The ball joint according to claim 1, wherein the unevenness includes a plurality of concave grooves formed along the entire outer surface and extending along the outer surface.

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