Cable sensor

• US 6,534,999 B2
• Filed: 11/15/2001
• Issued: 03/18/2003
• Est. Priority Date: 11/16/2000
• Status: Expired due to Fees

• Current Assignee: Measurement Specialties, Inc. (France) (TE Connectivity Limited)
• Original Assignee: Measurement Specialties, Inc. (France) (TE Connectivity Limited)
• Inventors: Brown, Richard Hunter
• Primary Examiner(s): Oda, Christine
• Assistant Examiner(s): Deb, Anjan K.
• Application Number:
  US09/991,190
• Publication Number:
  US 20020079905A1
• Time in Patent Office: 488 Days
• Field of Search: 324/543, 324/544, 324/539, 324/525, 735/143.4, 737/21, 737/27, 738/626.8, 340/545.4, 174/28, 174/102.R, 174/105.R, 174/106.R, 174/102.SC
• US Class Current: 324/543
• CPC Class Codes: G01B 7/18 using change in resistance
• CPC Class Codes: G01R 31/58 Testing of lines, cables or conductors testing of electric windings G01R31/72
• CPC Class Codes: H01B 7/328 comprising violation sensing means

Abstract

A sensor cable (10) for detecting and/or locating a deformation of the cable includes a conductive core (20), a dielectric layer (40), a controlled resistive layer (50), a piezoresistive layer (60), and an outer shield (70). Deformation of the cable (10) creates a change in resistance between the shield (70) and the controlled resistive layer (50), and also creates a piezoelectric-induced voltage between the conductive core (20) and the controlled resistive layer (50). The incidence and/or location of a deformation of the cable is deducible from electrical parameters, indicative of the change in resistance and the induced voltage, measured at one or both ends of the sensor cable.

Claims

1. A sensor cable having a first end and a second end, said cable comprising:

an outer shield, a piezoresistive portion positioned within said outer shield, a controlled resistive portion positioned within said piezoresistive portion, a dielectric portion positioned within said controlled resistive portion, and a conductive core positioned within said dielectric portion.

2. A sensor cable in accordance with claim 1, wherein said cable is one of flat cable and a cylindrical cable.

3. A sensor cable in accordance with claim 2 wherein said cable is a cylindrical cable comprising:

a conductive core positioned within said cable, a dielectric layer concentrically positioned radially outward and adjacent said conductive core, a controlled resistive layer concentrically positioned radially outward and adjacent said dielectric layer, a piezoresistive layer concentrically positioned radially outward and adjacent said resistive layer, and an outer shield concentrically positioned radially outward and adjacent said piezoresistive layer.

4. A sensor cable in accordance with claim 1, further comprising an outer jacket, wherein said outer shield is positioned within said outer jacket.

5. A sensor cable in accordance with claim 1, wherein

a deformation of said cable creates a change in resistance between said shield and said controlled resistive portion;

electrical parameters between said controlled resistive portion and said shield are detectable at each end of said cable; and

a location of said deformation is deducible by comparing detected electrical parameters indicative of said change in resistance at each corresponding end of said cable.

6. A sensor cable in accordance with claim 5, wherein said electrical parameters comprise at least one of resistance, voltage, and current.

7. A sensor cable in accordance with claim 1, wherein said dielectric portion has piezoelectric properties.

8. A sensor cable in accordance with claim 7, wherein:

a deformation of said cable creates a piezoelectrically-induced voltage between said conductive core and said controlled resistive portion;

corresponding voltage values are detectable at each end of said cable between said core wire and said controlled resistive portion; and

a location of said deformation is deducible by comparing detected voltage values at each corresponding end of said cable.

9. A sensor cable in accordance with claim 1, further comprising an insulated center conductor positioned within said conductive core.

10. A sensor cable in accordance with claim 9, wherein, electrical connections between said center conductor and said controlled resistive portion at said first end of said cable provide a means for at least one of detecting and locating a deformation of said cable from said second end of said cable.

11. A method for making a sensor cable, said method comprising the steps of:

providing an outer shield;

positioning a piezoresistive portion within said outer shield;

positioning a controlled resistive portion within said piezoresistive portion;

positioning a dielectric portion within said controlled resistive portion; and

positioning a conductive core within said dielectric portion.

12. A method in accordance with claim 11, further comprising the step of positioning an insulated center conductor within said conductive core.

13. A method in accordance with claim 11, further comprising the step of positioning an outer jacket around said outer shield.

14. A method for detecting the presence of a deformation of a sensor cable comprising a first end, a second end, a conductive core, a dielectric layer, a controlled resistive layer, a piezoresistive layer, and an outer shield, said method comprising the steps of:

detecting electrical parameters indicative of a change in resistance between said shield and said controlled resistive layer at each end of said cable corresponding to said deformation; and

comparing said detected electrical parameters at each corresponding end of said cable to detect a presence of said deformation.

15. A method in accordance with claim 14, further comprising the step of locating said deformation by comparing said detected electrical parameters at each corresponding end of said cable.

16. A method in accordance with claim 14, wherein said electrical parameters comprise at least one of resistance, voltage, and current.

17. A method in accordance with claim 14, wherein a deformation of said cable creates a piezoelectrically-induced voltage between said conductive core and said controlled resistive layer, said method further comprising the step of:

locating said deformation by comparing detected voltage values indicative of said piezoelectrically-induced voltage at each corresponding end of said cable.

18. A method in accordance with claim 14, wherein said conductive core further comprises an insulated center conductor positioned within said conductive core and said center conductor is electrically coupled to said controlled resistive layer at said first end of said cable, said method comprising the step of:

detecting said electrical parameters indicative of a change in resistance between said shield and said controlled resistive layer at said second end of said cable.