Load washer

• US 5,222,399 A
• Filed: 11/19/1991
• Issued: 06/29/1993
• Est. Priority Date: 02/01/1991
• Status: Expired due to Term

• Current Assignee: Key Safety Systems, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Original Assignee: Fel-Pro Incorporated
• Inventors: Kropp, Harry C.
• Primary Examiner(s): Woodiel, Donald O.
• Assistant Examiner(s): Dougherty, Elizabeth L.
• Application Number:
  US07/794,486
• Time in Patent Office: 588 Days
• Field of Search: 73/862.54, 73/862.68, 73/761, 73/862.04, 73/862.541, 73/862.041, 338/4, 338/47, 338/99, 338/114, 341/34, 310/366
• US Class Current: 73/862.68
• CPC Class Codes: F16B 31/028 with a load-indicating washer or washer assembly
• CPC Class Codes: G01L 1/20 by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids of piezo-resistive materials G01L1/18; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
• CPC Class Codes: G01L 5/243 using washers

Abstract

A load washer comprising a pair of thin metal washers between which a contact sensor is positioned. The contact sensor includes pairs of confronting electrodes at a plurality of spaced zones with a pressure sensitive resistive material between each pair, which, under pressure, provide an indication of the force applied to the load washer.

Claims

1. A thin circular load washer comprising:

a first thin plate defining an outer perimeter and a central opening,

a second thin plate defining an outer perimeter and a central opening, and

a load sensor positioned and permanently mounted between said plates, said load sensor defining a central opening and comprising,

first electrode means on a first thin plastic sheet,

second electrode means on a second thin plastic sheet confronting said first electrode means to define a plurality of pairs of confronting electrodes defining a plurality of points of confrontation of said first and second electrode means, said points of confrontation being distributed in equidistantly spaces zones around said load washer and within said outer perimeters,

a pressure sensitive resistive material interposed between said pairs of electrodes at each of said points of confrontation, and

conductors for all of said first and second electrode means extending beyond said outer perimeters and existing only at one peripheral location on said perimeters, and each said conductor terminating in a contact.

2. A load washer in accordance with claim 1, and wherein the first plate is thin and flat, and said second plate is thin and flat and defines an upstanding peripheral flange surrounding said first plate, and said load sensor is mounted therebetween.

3. A load washer in accordance with claim 1, and wherein said plates define means for preventing the transmission of shear loads to said load sensor.

4. A load washer comprising:

a first thin plate defining an outer perimeter,

a second thin plate defining an outer perimeter, and

a load sensor positioned between said plates, said load sensor comprising,

first electrode means,

second electrode means confronting said first electrode means within said outer perimeters,

a pressure sensitive resistive material between said electrode means at each said intersection,

conductors for said first and second electrode means extending beyond said outer perimeters, and each said conductor terminating in a contact,

and wherein said first and second electrode means each include a plurality of electrodes defining plural points of confrontation, said points of confrontation being distributed in circumferentially equidistantly spaced zones.

5. A load washer in accordance with claim 4, and wherein there are at least three equidistantly circumferentially spaced zones.

6. A load washer in accordance with claim 5, and wherein said load washer is generally circular in plan view and said zones are generally radially equidistant from the center of said loud washer and are spaced equidistantly from each other along a circle generated about the center of said load washer.

7. A load washer which is generally circular in plan view defining a central opening for a bolt comprising:

a first thin plate defining an outer perimeter,

a second thin plate defining an outer perimeter, and

a load sensor positioned between said plates, said load sensor comprising,

first electrode means comprising at least two electrodes,

second electrode means comprising at least two electrodes crossing and intersecting said first electrode means to define points of confrontation thereof within said outer perimeters, said electrode means defining plural points of confrontation, said points of confrontation being distributed in at least three equidistantly spaced zones, said zones being generally radially equidistant from the center of said load washer and being spaced equidistantly from each other along a circle generated about the center of said load washer,

a pressure sensitive resistive material between said electrode means at said points of confrontation, and

conductors for said first and second electrode means extending beyond said outer perimeters, and each said conductor terminating in a contact.

8. A load washer in accordance with claim 7, and wherein said plates are thin and flat and said load sensor is thin and flat and permanently mounted therebetween.

9. A load washer in accordance with claim 8, and wherein said plates define means for preventing the transmission of shear loads to said load sensor.

10. A load washer in accordance with claim 7, and wherein the first plate is thin and flat, and said second plate is thin and flat and defines an upstanding peripheral flange surrounding said first plate and said load sensor is mounted therebetween.