The present invention relates generally to ball and socket assemblies and more particularly to ball joints for the suspension systems of vehicles.
In some four wheel drive systems, a pair of ball joints fixedly attach an axle with a knuckle. Each of the ball joints has a housing and a ball stud that can articulate and rotate relative to one another. The housing contains a pair of bearings that are disposed on opposite axial sides of a ball portion of the ball stud for allowing this rotation and articulation. In addition to allowing the ball stud to articulate and rotate, the bearings also generally fix the ball stud with the housing in an axial direction. However, in certain circumstances, such as when the ball joint is improperly installed in the vehicle, this limited axial movement of the ball stud relative to the housing can put the ball joint in a bind. This condition may result in a phenomenon typically known as “memory steer” whereby the vehicle wants to keep turning in a direction after completing a turn in the same direction.
One aspect of the present invention is related to a ball joint assembly that includes a housing with an inner wall which surrounds an inner bore that extends along a central axis. The ball joint assembly further includes a ball stud with a ball portion and a shank portion. The ball portion is received in the inner bore of the housing, and the shank portion projects out of the inner bore through an open end of the housing. First and second preload members are disposed in the inner bore on opposite axial sides of the ball portion and are in contact with the ball portion. The preload members are of an elastomeric material. At least one of the preload members is compressed to urge the ball portion to a central location.
The ball joint assembly is advantageous because it allows the ball stud to move relative to the housing in the axial direction without binding up. This is accomplished with minimal (if any) increase in the torque required to articulate or rotate the ball stud relative to the housing and with little to no increase in cost.
According to another aspect of the present invention, the first and second preload members are of identical construction. This configuration allows for manufacturing cost savings through economies of scale.
According to yet another aspect of the present invention, each of the preload members is annular in shape and circles the central axis.
According to still another aspect of the present invention, each of the preload members has a corrugated top with a plurality of peaks and a plurality of valleys, and each of the preload members has a corrugated bottom with a plurality of peaks and a plurality of valleys.
According to a further aspect of the present invention, for each of the preload members, the peaks of the corrugated top are circumferentially aligned with the peaks of the corrugated bottom and the valleys of the corrugated top are circumferentially aligned with the valleys of the corrugated bottom.
According to yet a further aspect of the present invention, each of the preload members has an inner surface which faces towards the central axis, and the inner surface is tapered radially outwardly on the peaks.
According to still a further aspect of the present invention, each of the preload members is made as a monolithic piece of the elastomeric material.
According to another aspect of the present invention, the contact between the preload members and the ball portion of the ball stud is direct contact.
According to yet another aspect of the present invention, the housing is deformed to capture the ball portion of the ball stud and the preload members in the inner bore of the housing.
Another aspect of the present invention is related to a method of making a ball joint assembly. The method includes the step of preparing a housing which has an inner bore and at least one open end. The method continues with the step of inserting a first preload member into the inner bore. The method proceeds with the step of inserting a ball portion of a ball stud into the inner bore such that the shank portion of the ball stud extends out of the inner bore through the at least one open end. The method continues with the step of inserting a second preload member into the inner bore. The method proceeds with the step of compressing at least one of the first and second preload members to impart a biasing force on the ball portion of the ball stud. The method continues with the step of closing the housing to capture the first and second preload members and the ball portion of the ball stud in the inner bore.
According to another aspect of the present invention, the steps of compressing the first and/or second preload members is simultaneous to the step of closing the housing.
According to yet another aspect of the present invention, the step of closing the housing to capture the first and second preload members and the ball portion of the ball stud in the inner bore includes swaging an end of the housing.
According to still another aspect of the present invention, the step of closing the housing to capture the first and second preload members and the ball portion of the ball stud in the inner bore includes engaging a cover plate with the housing.
According to a further aspect of the present invention, each of the first and second preload members is in direct contact with the ball portion of the ball stud.
According to yet a further aspect of the present invention, each of the preload members has a corrugated top and a corrugated bottom.
These and other aspect, features and advantages of the invention will become more readily appreciated when considered in connection with the following detailed description of the presently preferred embodiment and best mode, appended claims and accompanying drawings, in which:
Referring to the Figures, wherein like numerals indicate corresponding parts throughout the several views, a vehicle suspension system which includes an exemplary pair of ball joint assemblies 20 constructed in accordance with one aspect of the present invention is generally shown in
Referring now to
Referring now to
Both the main body piece 34 and the bearing sleeve 36 of the housing 26 are preferably made of metal, such as iron, steel, a steel alloy, aluminum, or an aluminum alloy and are preferably shaped through casting, forging and/or machining. In the first exemplary embodiment, the main body piece 34 is made of non-gas carbonized AISI 1018 steel, and the bearing sleeve 36 is made of gas carbonized AISI 1018 steel, and thus, the bearing sleeve 36 is made of a material that is harder than the material of the main body piece 34 to absorb forces and resist wear while allowing the relatively softer main body piece 34 to be deformed during a swaging operation, which is described in further detail below.
The ball joint assembly 20 further includes a ball stud 44 with a ball portion 46 and a shank portion 48. The ball portion 46 is received in the inner bore of the housing 26, and the shank portion 48 projects out of the housing 26 through the open first end 38 for connection with the axle 22 or the knuckle 24. The ball portion 46 of the ball stud 44 has a semi-spherically curved exterior surface with an outer diameter that is similar to the constant diameter of the inner wall of the housing 26 such that an equator of the ball portion is in direct contact or near contact with the inner wall three hundred and sixty degrees (360°) around the central axis A. This allows radial loads to be directly transferred between the ball stud 44 and the housing 26 during operation of the vehicle. However, the contact between the ball portion 46 and the inner wall is a clearance fit such that the ball stud 44 can move or rotate relative to the housing 26 along the central axis A as the ball joint assembly 20 is installed on the vehicle and during operation of the vehicle. It should also be appreciated that, depending on the orientation of the ball stud 44 when the ball joint assembly 20 is installed on the vehicle, the contact between the ball portion 46 and the inner wall may not be along the equator of the ball portion 46.
Referring back to
A pair of preload members 52 (a first preload member 52a and a second preload member 52b) are disposed in the inner bore of the housing 26 and are in direct contact with opposite hemispheres of the ball portion 46 of the ball stud 44. The preload members 52a, 52b are of identical construction, thus leading to reduced manufacturing costs through economies of scale. Each of the preload members 52a, 52b has an annular shape which surrounds the central axis A. Each preload member 52a, 52b also has an outer surface, an inner surface, a top surface, and a bottom surface. When installed in the inner bore of the housing 26, the preload members 52a, 52b are in clearance fit relationships with the bearing sleeve 36.
The top and bottom surfaces of the preload member 52 are each corrugated (i.e., castellated) with a plurality of peaks 54 and a plurality of valleys 56. The valleys 56 separate adjacent peaks 54 from one another around the preload member 52. The peaks 54 on the corrugated top are circumferentially aligned with the peaks 54 on the corrugated bottom such that the preload member 52 has a greater height in the areas of the peaks 54 as compared to the areas of the valleys 56. Each preload member 52 also has an increased thickness in the areas of the peaks 54 and a reduced thickness in the areas of the valleys 56. The inner surface is tapered radially outwardly on the peaks 54. That is, in each of the areas with the peaks 54, the inner surface extends parallel to the central axis A at the midplane. The inner surface then tapers radially outwardly in both axial directions, i.e., towards the top in one direction and towards the bottom in an opposite direction. As shown in
In the first exemplary embodiment of the ball joint assembly 20, a top edge of the housing adjacent the open first end 38 of the inner bore is deformed (for example, through swaging) to present a radially inwardly extending lip 58 which partially closes the open first end 38 to capture the bearing sleeve 36; the first and second preload members 52a, 52b; and the ball portion 46 of the ball stud 44 in the inner bore. After the swaging operation is completed, the bearing sleeve 36 extends in the axial direction a fixed length from the lower wall to the lip 58 of the housing 26.
The first and second preload members 52a, 52b are spaced axially from one another within the inner bore of the housing 26 by a gap, and the contact between the ball portion 46 of the ball stud 44 housing 26 occurs within this gap. The exterior surface of the ball portion 46 of the ball stud 44 may be provided with one or more lubricant grooves (not shown) for improving the flow of lubrication within the inner bore.
Each preload member 52 is made as a monolithic piece of an elastomeric material, such as rubber, for biasing the ball portion 46 of the ball stud 44 into a central location within the inner bore (
During installation of the ball joint assembly 20 on a vehicle, the first and second preload members 52a, 52b allow for the ball stud 44 to move relative to the housing 26 along the central axis A with minimal impact on the torque required to articulate and rotate the ball stud 44. Thus, the ball joint assembly 20 is prevented from binding up, as can occur in other known ball joint assemblies where minimal or no axial movement of the ball stud is possible. For example,
An alternate embodiment of the ball joint assembly 120 is generally shown in
Another aspect of the present invention is related to a method of making a ball joint assembly 20, such as the ball joint assembly 20 shown in
Preferably, the steps of compressing the first and second preload members 52a, 52b and of closing the housing 26 are simultaneous. For example, in one embodiment, the housing 26 is swaged to both capture the preload members 52a, 52b and the ball portion 46 of the ball stud 44 in the inner bore. In another embodiment, the cover plate 160 is pressed into engagement with a groove that is formed into the housing 126.
Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than specifically described. It should also be appreciated that the terms “upper”, “lower” and “bottom” are in reference to the orientations of the enabling embodiment of the invention shown in the Figures and are not meant to require any certain orientation. Additionally, it is to be understood that all features of all claims and all embodiments can be combined with each other, as long as they do not contradict each other.
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Entry |
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International Search Report, dated Nov. 29, 2019 (PCT/US2019/050505). |
Number | Date | Country | |
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20200080590 A1 | Mar 2020 | US |