Electrical sensing system for measuring ferrous particles within a fluid

• US 4,731,578 A
• Filed: 05/02/1985
• Issued: 03/15/1988
• Est. Priority Date: 05/02/1985
• Status: Expired due to Term

• Current Assignee: Vickers Incorporated (Eaton Corporation PLC.)
• Original Assignee: Aeroquip Corporation (Eaton Corporation PLC.)
• Inventors: Tsaprazis, Edward
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US06/729,759
• Time in Patent Office: 1,048 Days
• Field of Search: 324/204, 324/225, 324/228, 324/234, 324/236, 324/237, 324/238, 324/327, 324/59, 73/64, 340/631, 361/180
• US Class Current: 324/204
• CPC Class Codes: F01M 2001/1042 comprising magnetic parts
• CPC Class Codes: F16N 29/00 Special means in lubricating arrangements or systems providing for the indication or detection of undesired conditions; Use of devices responsive to conditions in lubricating arrangements or systems
• CPC Class Codes: G01N 15/0656 using electric, e.g. electrostatic methods or magnetic methods by investigating individual particles G01N15/1031, G01N15/12
• CPC Class Codes: G01N 27/74 of fluids G01N24/00 takes precedence
• CPC Class Codes: G01N 33/2858 metal particles

Abstract

This invention relates to a device for detecting electrically inductive particles in a fluid medium and is of particular use for detecting ferrous particles in the lubricant of an engine or mechanical transmissions thereby giving warning of malfunction of the engine or the transmission. The invention is of particular importance for the operation of an internal combustion engine, especially highly stressed helicopter and aircraft engines wherein prior warning of a malfunction permits corrective action prior to a catastrophic failure.

Claims

1. Article for sensing ferrous contamination in a fluid comprising:

(a) a generally cylindrical magnet;

(b) a first electrical coil located co-axially on one end of said magnet, said coil having a hole lengthwise through its center;

(c) a pole piece of said magnet occupying the hole in said first coil and concentric with said magnet disposed at one end of the magnet, said pole piece of the magnet being available to accumulate ferrous contamination present in a fluid whereby any ferrous accumulation changes the induction of the coil;

(d) a second coil, indentical in composition and inductance to said first coil, the axis of the second coil being concentric to the axis of said magnet and located on the opposite end of the generally cylindrical magnet from the said first coil, the inductance of said second coil being unaffected by said ferrous accumulation;

(e) frequency generation means for generating a fixed, known frequency sine wave signal of a known amplitude;

(f) an electrical bandpass filter including means connecting said first and second coils as the frequency determinative element of the filter, both of said coils being equally affected by variations in external operating conditions, whereby changes in the outputs of said coils due to such variations cancel each other in said filter, the input of the filter being operatively connected to said frequency generation means;

(g) amplification means operatively connected to the output of said filter.