Measuring and testing – With fluid pressure – Leakage
Reexamination Certificate
2000-07-26
2001-10-02
Williams, Hezron (Department: 2856)
Measuring and testing
With fluid pressure
Leakage
C073S046000, C403S027000
Reexamination Certificate
active
06295863
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method of determining sealing failure in a ball joint by sensing changes in a dielectric characteristic of the ball joint grease.
BACKGROUND OF THE INVENTION
Ball joints are commonly used in numerous vehicle applications, such as stabilizer bar links, suspension control arms, tie rod ends, etc. These ball joints are typically positioned underneath the vehicle and exposed to the elements such that they are subject to seal failure and leakage.
Ball joints used in vehicles require oscillation and rotation between the parts they connect. This motion requires the use of an elastomeric seal between the ball joint stud and socket. Water leakage around elastomeric ball joint boots and into suspension stabilizer bar ball joints, or other ball joints, can cause corrosion of the ball, failure of the ball joint, and other problems. Under current tests or service procedures, water leakage can only be detected after the fact by a time-consuming and destruction tear-down of the ball joint. This destructive tear-down of the ball joint is obviously undesirable, particularly when the ball joint has not failed.
Accordingly, it is desirable to provide an improved method and apparatus for determining ball joint leakage in a manner which does not require tear-down of the ball joint.
DISCLOSURE OF INVENTION
Accordingly, the present invention provides an improved method and apparatus for determining seal failure in a ball joint by measuring changes in a dielectric characteristic of the ball joint grease to determine if such changes are indicative of failure of the ball joint seal.
More specifically, the present invention provides a method of determining seal failure in a ball joint, including a stud having a ball embedded in grease within a sealed socket assembly. The method includes the steps of: a) measuring a dielectric characteristic of the grease; and b) determining that the sealed socket assembly has failed if the measured dielectric characteristic substantially varies from a predetermined value.
The measured dielectric characteristic may be capacitance or resistance. In a preferred embodiment, the capacitance is measured by connecting a capacitance gauge to the stud and to a clamping ring which secures a rubber boot around the socket assembly. The measuring step may include periodically monitoring the dielectric characteristic with an in-vehicle control module, or connecting a capacitance gauge to the ball joint in a vehicle service environment. In other words, the capacitance gauge may be integral with the ball joint assembly and operatively connected to a vehicle control system, or the capacitance gauge may be selectively connected to determine sealing integrity of the ball joint.
An apparatus in accordance with the invention includes a stud having a ball at a distal end thereof, and a sealed socket having grease therein. The ball is embedded within the grease. A capacitance gauge is operatively connected across the grease to measure changes in capacitance of the grease which would indicate seal failure. The capacitance may be measured in real-time on the vehicle.
Accordingly, an object of the invention is to provide an improved method and apparatus for determining seal failure in a ball joint in a manner in which tear-down of the ball joint is not required.
The above object and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.
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The American Heritage® Dictionary of the English Language, Third Edition copyright© 1992 by Houghton Mifflin Company. Electronic version licensed from INSO Corporation.*
McGraw-Hill Encyclopedia of Physics, 1983, McGraw-Hill, Inc, p. 230.
Ginder John Matthew
Stewart William McMurray
Brown Gregory P.
Ford Global Technologies Inc.
Garber C D
Williams Hezron
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