# US 2022/0044844 A1 · Heat detection line and multi-core cable

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- Number: US 2022/0044844 A1
- Document ID: US20220044844A1
- Status: Published application
- Kind: A1
- Application number: 17/381,934
- Filed: 2021-07-21
- Published: 2022-02-10
- Earliest claimed: 2020-08-07
- Assignees: Hitachi Metals, Ltd.
- Applicants: Hitachi Metals, Ltd.
- Inventors: Masashi MORIYAMA; Yoshinori Tsukamoto; Detian Huang
- Web page: https://patentgrep.com/patent/US20220044844A1

## CPC

- H01B 7/324: {comprising temperature sensing means}
- G01K 7/16: using resistive elements
- G01K 11/06: using melting, freezing, or softening
- H01B 7/18: {Protection against damage caused} by wear, mechanical force or pressure; {Sheaths; Armouring}
- H01B 17/58: Tubes, sleeves, beads, or bobbins through which the conductor passes
- H01B: CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES (selection for magnetic properties H01F1/00; waveguides H01P {; printed circuits H05K})
- G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00)

## Abstract

A heat detection line includes a twisted pair wire composed of a pair of heat detecting wires being twisted together. Each heat detecting wire includes a conductor and an insulator covering a periphery of the conductor. The conductor is non-magnetic and composed of a copper alloy with a tensile strength of 900 MPa or more. A multi-core cable includes the heat detection line, a plurality of electric wires, and a sheath covering the heat detection line and the plurality of electric wires together. A melting point of the insulator of the heat detection line is lower than a melting point of an insulator of each of the plurality of electric wires.

## Claims

### Claim 1

A heat detection line, comprising:
a twisted pair wire comprising a pair of heat detecting wires being twisted together, each heat detecting wire comprising a conductor and an insulator covering a periphery of the conductor,
wherein the conductor is non-magnetic and comprises a copper alloy with a tensile strength of 900 MPa or more.

### Claim 2 (depends on 1)

The heat detection line, according to claim 1, wherein when the insulators are softened or melted at a given temperature, the conductors of the pair of heat detecting wires move toward a center of the twisted pair wire and contact each other, by a force which allows the conductors to move closer to each other.

### Claim 3 (depends on 2)

The heat detection line, according to claim 2, wherein a melting point of the insulator is greater than 80° C. and less than 100° C.,
wherein short circuit does not occur in an environment of 80° C., while the short circuit occurs within 5 minutes in an environment of 100° C.

### Claim 4 (depends on 3)

The heat detection line, according to claim 3, wherein the short circuit occurs within approximately 3 minutes in the environment of 100° C.

### Claim 5 (depends on 1)

The heat detection line, according to claim 1, wherein the conductor comprises phosphor bronze including 7 mass % or more and 9 mass % or less of Sn, and 0.03 mass % or more and 0.35 mass % or less of P.

### Claim 6 (depends on 1)

The heat detection line, according to claim 1, wherein an elongation of the conductor is 10% or less.

### Claim 7 (depends on 1)

The heat detection line, according to claim 1, wherein a periphery of the twisted pair wire is covered by a jacket,
wherein the jacket includes an inner layer and an outer layer, and
wherein a thickness of the outer layer is greater than a thickness of the inner layer.

### Claim 8 (depends on 1)

The heat detection line, according to claim 1, wherein a periphery of the twisted pair wire is covered by a jacket,
wherein a reinforcing layer is provided around the jacket, and
wherein the reinforcing layer is a tape layer comprising a resin tape being wound spirally around the jacket.

### Claim 9

A multi-core cable, comprising:
a heat detection line comprising a twisted pair wire comprising a pair of heat detecting wires being twisted together, each heat detecting wire comprising a conductor and an insulator covering a periphery of the conductor, wherein the conductor is non-magnetic and comprises a copper alloy with a tensile strength of 900 MPa or more;
a plurality of electric wires; and
a sheath covering the heat detection line and the plurality of electric wires together,
wherein a melting point of the insulator of the heat detection line is lower than a melting point of an insulator of each of the plurality of electric wires.

### Claim 10 (depends on 9)

The multi-core cable, according to claim 9, wherein the plurality of electric wires are spirally twisted around the heat detection line.