Caterpillar Inc.

Lisa A Creger

George G Codina

Thomas M Baker

John W Crayton

Timothy A Boston

J Thomas Vachon

A sensor apparatus for detecting both ferrous and non-ferrous particles in a fluid including a housing adapted for insertion into a fluid line, the housing having a collection cavity formed therewithin for trapping and holding metallic particles which are suspended in the fluid as the fluid passes through the sensor. A first coil wound below the collection cavity and a second coil wound about the collection cavity, the inductance of the first coil being responsive to the temperature of the fluid passing through the sensor and the inductance of the second coil being responsive to the ferrous and non-ferrous particle accumulation within the collection cavity. An electromagnetic coil is spaced above the second coil to attract ferrous particles away from the vicinity of the second coil. Based upon eddy current principles and because eddy currents are a function of material conductivity, a first energization of the second coil generates a signal indicative of the total ferrous and non-ferrous particle accumulation within the collection cavity and a second energization of the second coil with the electromagnetic coil likewise energized generates a signal indicative of just the non-ferrous particle accumulation within the collection cavity. A microprocessor coupled to the coils calculates the percentage of ferrous and non-ferrous particles in the collection cavity and outputs such information for diagnostic, prognostic and trend analysis purposes.

Fluid particle sensor apparatus and method for detecting ferrous and non-ferrous metals

In one aspect of the present invention, an apparatus for determining an extended length of a hydraulic cylinder is disclosed. A piston and rod are contained within a cylindrical housing of the hydraulic cylinder. A coil is wound about the rod and is attached to the piston and an end of the cylindrical housing. The coil extends and retracts with the reciprocating movement of the piston. An oscillator is coupled to the coil and produces a position signal in response to the inductance of the coil. A circuit receives the position signal, and determines the incremental linear position and velocity of the piston and rod relative to the housing in response to the frequency of the position signal.

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Metamora, IL, United States of America

Lisa A Creger