Conductive particle sensor using a magnet

• US 5,179,346 A
• Filed: 05/24/1991
• Issued: 01/12/1993
• Est. Priority Date: 05/24/1991
• Status: Expired due to Fees

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: McGee, Brian G., Rytter, Noel J.
• Primary Examiner(s): Harvey, Jack B.
• Assistant Examiner(s): Regan, Maura K.
• Application Number:
  US07/705,457
• Time in Patent Office: 599 Days
• Field of Search: 324/693, 324/204, 324/219, 324/228, 340/631, 340/627, 335/305, 204/61.09, 73/10
• US Class Current: 324/693
• CPC Class Codes: G01N 15/0656 using electric, e.g. electrostatic methods or magnetic methods by investigating individual particles G01N15/1031, G01N15/12

Abstract

An apparatus is adapted to detect particles within a fluid. The apparatus includes first and second electrodes within a housing. The first and second electrodes form a "V" shaped recess. A magnet is positioned within the housing to attract ferrous particles into the recess. The resistance between the first and second electrodes is measured as an indication of particles within the fluid.

Claims

1. An apparatus for sensing electrically conductive particles within a fluid, comprising:

a housing having first and second portions;

a magnet having a first pole and a second pole and being positioned within said first portion of said housing, said first and second poles defining a reference plane;

a first electrode having a first contact surface and being positioned within said second portion of said housing and extending in a direction generally away from said magnet;

a second electrode having a second contact surface and being positioned within said second portion of said housing and extending in a direction generally away from said magnet, said first and second contact surfaces being spaced apart and each having an angular relationship with said reference plane; and

means for sensing the electrical resistance between said first and second contact electrodes and responsively producing a signal indicative of the presence of said electrically conductive particles.

2. An apparatus, as set forth in claim 1, wherein the said first and second contact surfaces form a v-shaped cavity.

3. An apparatus, as set forth in claim 1, wherein the magnitude of said signal is indicative of the amount of particles within said fluid.

4. An apparatus, as set forth in claim 1, wherein the magnitude of said signal is indicative of the size of the particles within said fluid.

5. An apparatus, as set forth in claim 1, wherein said first and second electrodes are composed of steel.

6. An apparatus, as set forth in claim 1, wherein said first and second electrodes are composed of a ferrous and electrically conductive material.

7. An apparatus, as set forth in claim 1, wherein said means for responsively producing a signal indicative of the presence of said electrically conductive particles includes means for producing a pulse width modulated signal having a duty cycle inversely proportional with said electrical resistance.

8. An apparatus, as set forth in claim 1, wherein said housing is composed of a substantially transparent material.

9. An apparatus, as set forth in claim 8, wherein said housing has a generally cylindrical shape centered about an axis perpendicular to said reference plane.

10. An apparatus, as set forth in claim 9, wherein said housing is threaded about at least a portion of the outside diameter of said housing.

11. An apparatus, as set forth in claim 10, wherein said housing includes first and second unthreaded surfaces positioned opposite each other, said first and second unthreaded surfaces being substantially flat and substantially perpendicular to said first and second electrodes.

12. An apparatus, as set forth in claim 1, wherein said housing is composed of a polyethersulfone.

13. An apparatus, as set forth in claim 1, wherein said housing is composed of a polyethersulfone reinforced with glass fibers.

14. An apparatus, as set forth in claim 1, wherein said housing includes an inner shell and an outer shell.

15. An apparatus, as set forth in claim 14, wherein said inner shell is composed of a substantially transparent material.

16. An apparatus, as set forth in claim 1, wherein said housing has a generally cylindrical shape centered about an axis perpendicular to said reference plane.

17. An apparatus, as set forth in claim 16, wherein said housing is threaded about at least a portion of the outside diameter of said housing.

18. An apparatus for sensing electrically conductive particles within a fluid, comprising:

a housing first and second portions;

a magnet having a first pole and a second pole and being positioned with said first portion of said housing, said first and second poles defining a reference frame;

a first electrode having a first contact surface and being positioned within said second portion of said housing and extending in a direction generally away from said magnet;

a second electrode having a second contact surface and being positioned within said second portion of said housing and extending in a direction generally away from said magnet, said fist and second contact surfaces being spaced apart and each having an angular relationship with said reference frame, wherein said first and second electrodes each include a guide portion and an insert portion; and

,

means for sensing the electrical resistance between said fist and second contact electrodes and responsively producing a signal indicative of the presence of said electrically conductive particles.

19. An apparatus, as set forth in claim 18, wherein said insert portions are composed of a ferrous and electrically conductive material and said guide portions are composed of an electrically conductive material.

20. An apparatus, as set forth in claim 18, wherein said insert portions are composed of steel and said guide portions are composed of brass.

21. An apparatus for sensing electrically conductive particles within a fluid, comprising:

a housing having first and second portions;

a magnet having a first pole and a second pole and being positioned with said first portion of said housing, said first and second poles defining a reference frame;

a first electrode having a first contact surface and being positioned within said second portion of said housing and extending in a direction generally away from said magnet;

a second electrode having a second contact surface and being positioned within said second portion of said housing and extending in a direction generally away from said magnet, said first and second contact surfaces being spaced apart and each having an angular relationship with said refer e frame, wherein said fist and second contact surfaces have a length extending along said fist and second poles, respectively, said angular relationship varying along said length; and

,

means for sensing the electrical resistance between said first and second contact electrodes and responsively producing a signal indicative of the presence of said electrically conductive particles.

22. An apparatus, as set forth in claim 21, wherein said inner shell is composed of a polyethersulfone.

23. An apparatus, as set forth in claim 22, wherein said polyethersulfone is reinforced with glass fibers.

24. An apparatus for sensing electrically conductive particles within a fluid, comprising:

a housing having first and second portions;

a magnet having a first pole and a second pole and being positioned with said first portion of said housing, said fist and second poles defining a reference frame;

a first electrode having a first contact surface and being positioned within said second portion of said housing and extending in a direction generally away from said magnet;

a second electrode having a second contact surface and being positioned within said second portion of said housing and extending in a direction generally away from said magnet, said first and second contact surfaces being spaced apart and each having an angular relationship with said reference frame; and

,

means for sensing the electrical resistance between said fist and second contact electrodes and responsively producing a signal indicative of the presence of said electrically conductive particles, wherein said sensing means includes;

a resistor having first and second terminals, said first and second terminals being connected to said fist and second electrodes, and

means for measuring the electrical resistance across said first and second terminals.

25. An apparatus for sensing electrically conductive particles within a fluid, comprising:

a housing first and second portions;

a magnet having a first pole and a second pole and being positioned with said first portion of said housing, said first and second poles defining a reference frame;

a first electrode having a first contact surface and being positioned within said second portion of said housing and extending in a direction generally away from said magnet;

a second electrode having a second contact surface and being positioned within said second portion of said housing and extending in a direction generally away from said magnet, said first and second contact surfaces being spaced apart and each having an angular relationship with said reference frame; and

,

mean of sensing the electrical resistance between said first and second contact electrodes and responsively producing a signal indicative of the presence of said electrically conductive particles, wherein said housing includes a recess for said magnet and including a detachable plate adapted to hold said magnet within the recess of said housing.

26. An apparatus for sensing the presence of electrically conductive particles within a fluid, comprising:

a housing having first and second portions, said housing having a generally cylindrical shape centered about an axis and being composed of a substantially transparent material;

a magnet having a first pole and a second pole and being positioned within a recess of said first portion of said housing, said first and second poles defining a reference plane, said axis being perpendicular to said reference plane;

a detachable plate adapted to hold said magnet within the recess of said housing;

a first electrode having a first contact surface and being positioned within said second portion of said housing;

a second electrode having a second contact surface and being positioned within said second portion of said housing, said fist and second contact surfaces being spaced apart;

wherein said hosing is threaded about at least a portion of the outside diameter of said housing and includes first and second unthreaded surfaces positioned opposite each other and substantially perpendicular to said first and second electrodes; and

means for sensing the electrical resistance between said first and second contact electrodes and responsively producing a signal indicative to the presence of said electrically conductive particles.

27. An apparatus, as set forth in claim 26, wherein said housing is composed of a polyethersulfone.

28. An apparatus, as set forth in claim 26, wherein said housing is composed of a polyethersulfone reinforced with glass fibers.

29. An apparatus for sensing the presence of electrically conductive particles within a fluid, comprising:

a housing having first and second portions, said housing having a generally cylindrical shape centered about an axis and being composed of a substantially transparent material;

a magnet having a first pole and a second pole and being positioned within a recess of said first portion of said housing, said first and second poles defining a reference plane, said axis being perpendicular to said reference plane;

a first electrode having a first contact surface and being positioned adjacent said first pole within said second portion of said housing and extending in a direction generally away from said first pole;

a second electrode having a second contact surface and being positioned adjacent said second pole within said second portion of said housing and extending in a direction generally away from said second pole, said first and second contact surfaces being spaced apart and each having an angular relationship with said reference plane; and

a detachable plate adapted to hold said magnet within the recess of said housing;

wherein said housing is threaded about at least a portion of the outside diameter of said housing and includes first and second unthreaded surfaces positioned opposite each other and substantially perpendicular to said first and second electrodes; and

means for sensing the electrical resistance between said first and second contact electrodes and responsively producing a signal indicative of the presence of said electrically conductive particles.

30. An apparatus for sensing the presence of electrically conductive particles within a fluid, comprising:

a housing having an inner shell and an outer shell, said housing having a generally cylindrical shape centered about an axis, said inner shell being composed of a substantially transparent material, said housing having first and second portions;

a magnet having a first pole and a second pole and being positioned within a recess of said first portion of said housing, said first and second poles defining a reference plane, said axis being perpendicular to said reference plane;

a first electrode having a first contact surface and being positioned adjacent said first pole within said second portion of said housing and extending in a direction generally away from said first pole;

a second electrode having a second contact surface and being positioned adjacent said second pole within said second portion of said housing and extending in a direction generally away from said second pole, said first and second contact surfaces being spaced apart and each having an angular relationship with said reference plane; and

a detachable plate adapted to hold said magnet within the recess of said housing;

wherein said housing is threaded about at least a portion of the outside diameter of said housing and includes first and second unthreaded surfaces positioned opposite each other and substantially perpendicular to said first and second electrodes; and

means for sensing the electrical resistance between said first and second contact electrodes and responsively producing a signal indicative of the presence of said electrically conductive particles.