Temperature threshold detector

Claim 3

The apparatus of claim 1 wherein said first and second electrical conductors are elongate, said spacing structure being correspondingly elongate, whereby a rise in temperature exceeding said threshold value at any position along said sensor can be indicated.

Claim 4

The apparatus of claim 2 wherein said first electrical conductor is configured as a wire, and said second electrical conductor is configured as a sheath disposed around but spaced from said wire.

Claim 5

The apparatus of claim 3 wherein said second electrical conductor is configured as a generally cylindrical sheath disposed coaxially around said wire, said spacing structure being of generally annular configuration separating said sheath from said wire.

Claim 6

The apparatus of claim 2 wherein said first and second electrical conductors are configured as wires.

Claim 7

The apparatus of claim 5 wherein said spacing structure is of generally flat configuration with edges configured to receive said wires.

Claim 8

The apparatus of claim 5 wherein said spacing structure is disposed around said first wire, said second wire being in contact with said spacing structure.

Claim 9

The apparatus of claim 7 wherein said first and second electrical conductors are embedded in said spacing structure.

Claim 10

The apparatus of claim 8 further comprising a protective sleeve disposed around said spacing structure.

Claim 11

The apparatus of claim 7 wherein said spacing structure comprises a first portion disposed around said first electrical conductor and a second portion disposed around said second electrical conductor, said first electrical conductor and surrounding first portion of said spacing structure being positioned adjacent and in twisted relationship with respect to said second electrical conductor and surrounding second portion of said spacing structure.

Claim 12

The apparatus of claim 1 wherein said first and second electrical conductors are made of dissimilar metals selected from the group consisting of transition elements.

Claim 13

The apparatus of claim 11 wherein said first and second electrical conductors are made of dissimilar metals selected from the group of transition elements consisting of rare earth elements.

Claim 14

The apparatus of claim 1 wherein one of said first and second electrical conductors is made of an alloy, a constituent of said alloy being selected from the group consisting of transition elements.

Claim 15

The apparatus of claim 1 wherein one of said first and second electrical conductors is made of copper.

Claim 16

The apparatus of claim 14 wherein said first electrical conductor is made of copper, and wherein said second electical conductor is made of an alloy of copper and nickel.

Claim 17

A thermal survey apparatus for indicating location of a temperature rise above a predetermined value in a device to be monitored for temperature change, said thermal survey apparatus comprising a plurality of elongate temperature threshold detectors, each of said temperature threshold detectors being capable of independently indicating temperature rise above said predetermined value, said temperature threshold detectors being positionable in thermal contact with said device so that an occurrence of temperature rise above said predetemined value in said device can be independently indicated by at least two of said temperature threshold detectors in order to provide coordinates for locating said temperature rise above said predetermined value in said device, each of said temperature threshold detectors including: (a) a sensor positionable in thermal contact with said device, said sensor having: (i) a first electrical conductor, (ii) a second electrical conductor, and (iii) a spacing structure separating said first and second electrical conductors, said first and second electrical conductors being made of dissimilar metals, said spacing structure being made of an ionic salt selected from the group consisting of KNO 3 and NaNO 3 , said ionic salt having an electrical resistivity that is temperature dependent so that said spacing structure when exposed to temperatures below said predetermined value provides substantial electrical isolation between said first and second electrical conductors, and so that said spacing structure when exposed to temperatures above said predetermined value acts with the dissimilar metals of said first and second electrical conductors to cause a self-generated electromotive force to develop across said first and second electrical conductors, and (b) an instrument for indicating temperature rise above said predetermined value, said instrument having a first electrical lead connected to said first electrical conductor and a second electrical lead connected to said second electrical conductor, said electromotive force driving said instrument.

Claim 18

A thermal survey apparatus for indicating location of a temperature rise above a predetermined value in a device to be monitored for temperature change, said thermal survey apparatus comprising a plurality of elongate temperature threshold detectors, each of said temperature threshold detectors being capable of independently indicating temperature rise above said predetermined value, said temperature threshold detectors being positionable in thermal contact with said device so that an occurrence of temperature rise above said predetemined value in said device can be independently indicated by at least two of said temperature threshold detectors in order to provide coordinates for locating said temperature rise above said predetermined value in said device, each of said temperature threshold detectors including: (a) a sensor positionable in thermal contact with said device, said sensor having: (i) a first electrical conductor, (ii) a second electrical conductor, and (iii) a spacing structure separating said first and second electrical conductors, said first and second electrical conductors being made of dissimilar metals, said spacing structure being made of an ionic salt selected from the group consisting of KNO 3 and NaNO 3 , said ionic salt having an electrical resistivity that is temperature dependent so that said spacing structure when exposed to temperatures below said predetermined value provides substantial electrical isolation between said first and second electrical conductors, and so that said spacing structure when exposed to temperatures above said predetermined value acts with the dissimilar metals of said first and second electrical conductors to cause a self-generated electromotive force to develop across said first and second electrical conductors, and (b) an instrument for indicating temperature rise above said predetermined value, said instrument having a first electrical lead connected to said first electrical conductor and a second electrical lead connected to said second electrical conductor, said electromotive force driving said instrument.

Claim 19

The thermal survey apparatus of claim 16 wherein said temperature threshold detectors are arranged in a generally planar grid.

Claim 20

The thermal survey apparatus of claim 17 wherein said temperature threshold detectors are interwoven with respect to each other.

Claim 21

The thermal survey apparatus of claim 16 wherein said temperature threshold detectors are arranged in a contoured grid pattern conforming generally to contours of said device to be monitored for temperature change.