Temperature sensor including thermosensitive element

Patent metadata

Field	Value
Publication number	US-9714869-B2
Application number	US-201113695078-A
Country	US
Kind code	B2
Filing date	Apr 26, 2011
Priority date	Apr 28, 2010
Publication date	Jul 25, 2017
Grant date	Jul 25, 2017

Abstract

A temperature sensor 1 includes: a thermosensitive element 2 composed of a low-thermal expansion ceramics having a coefficient of linear expansion of 3×10 −6 /° C. to 5×10 −6 /° C. and of which electrical characteristics change depending on temperature; a pair of electrode films 20 provided on the surfaces of the thermosensitive element 2 ; and a pair of lead wires having a coefficient of linear expansion of 15×10 −6 /° C. or less and bonded to the electrode films 20 . When the coefficients of linear expansion of the thermosensitive element 2 , the electrode film 20 , and the lead wire 21 are respectively T a (/° C.), T b (/° C.), and T d (/° C.), the temperature sensor 1 satisfies a relationship T a ≦T b ≦T d .

First claim

What is claimed is:

1. A temperature sensor comprising:
a thermosensitive element composed of a low-thermal expansion ceramics having a coefficient of linear expansion of 3×10 −6 /° C. to 5×10 −6 /° C. and of which electrical characteristics change depending on temperature;
a pair of electrode films provided on the surfaces of the thermosensitive element, wherein the electrode films are composed of an alloy containing at least Cr and Fe of which a main component is Cr; and
a pair of lead wires having a coefficient of linear expansion of 15×10 −6 /° C. or less and bonded to the electrode films,
wherein, when coefficients of linear expansion of the thermosensitive element, the electrode films, and the lead wires are denoted by Ta(/° C.), Tb(/° C.), and Td(/° C.) respectively, the coefficients of the linear expansion of the thermosensitive element, the electrode films, and the lead wires are set to satisfy a relationship of Ta≦Tb≦Td and
the coefficient of the linear expansion of the electrode films, Tb(/° C.), is 11×10 −6 /° C. or less.

2. The temperature sensor according to claim 1 , comprising a protective layer that seals the thermosensitive element and the electrode films together with a portion of the lead wire.

3. The temperature sensor according to claim 1 , the Cr—Fe is an alloy containing 60 wt % to 90 wt % Cr and 40 wt % to 10 wt % Fe.

4. The temperature sensor according to claim 1 , wherein the thermosensitive element includes a matrix phase composed of matrix particles composed of silicon nitride.

5. The temperature sensor according to claim 4 , comprising a protective layer that seals the thermosensitive element and the electrode films together with a portion of the lead wire.

6. The temperature sensor according to claim 1 , wherein the bonding material, the electrode films and the lead wires are composed of an alloy containing at least Cr and Fe.

7. The temperature sensor according to claim 6 , wherein the electrode film is formed on overall surfaces of a pair of opposing surfaces of the thermosensitive element and, on a bonding surface bonding both the thermosensitive element and the bonding material, a shortest distance between an end portion of the thermosensitive element and the bonding material is at least 0.1 mm or more.

8. The temperature sensor according to claim 7 , wherein the thermosensitive element includes a matrix phase composed of matrix particles composed of silicon nitride.

9. The temperature sensor according to claim 8 , comprising a protective layer that seals the thermosensitive element and the electrode films together with a portion of the lead wire.

10. The temperature sensor according to claim 1 , wherein
the electrode films and the lead wires are mutually bonded via a bonding material composed of metal,
when a coefficient of linear expansion of the bonding material is denoted by Tc(/° C.), the coefficients of the liner expansion of the thermosensitive element, the electrode film, the lead wire, and the bonding material are set to satisfy a relationship of Ta≦Tb≦Tc≦Td, and
the coefficient of the linear expansion of the bonding material, Tc (/° C.), is set to be Tc≦12×10 −6 .

11. The temperature sensor according to claim 10 , wherein the electrode film is formed on overall surfaces of a pair of opposing surfaces of the thermosensitive element and, on a bonding surface bonding both the thermosensitive element and the bonding material, a shortest distance between an end portion of the thermosensitive element and the bonding material is at least 0.1 mm or more.

12. The temperature sensor according to claim 11 , wherein the thermosensitive element includes a matrix phase composed of matrix particles composed of silicon nitride.

13. The temperature sensor according to claim 12 , comprising a protective layer that seals the thermosensitive element and the electrode films together with a portion of the lead wire.

14. The temperature sensor according to claim 10 , wherein the bonding material and the lead wires are composed of an alloy containing at least Cr and Fe.

15. The temperature sensor according to claim 14 , wherein the electrode films are formed on overall surfaces of a pair of opposing surfaces of the thermosensitive element and, on a bonding surface bonding both the thermosensitive element and the bonding material, a shortest distance between an end portion of the thermosensitive element and the bonding material is at least 0.1 mm or more.

16. The temperature sensor according to claim 15 , wherein the thermosensitive element includes a matrix phase composed of matrix particles composed of silicon nitride.

17. The temperature sensor according to claim 16 , comprising a protective layer that seals the thermosensitive element and the electrode films together with a portion of the lead wire.

Assignees

• Satou Motoki
• Hori Tsunenobu
• Kuzuoka Kaoru
• Ogawa Chiaki
• Inoguchi Kazuhiro
• Denso Corp

Inventors

• Satou Motoki
• Hori Tsunenobu
• Kuzuoka Kaoru
• Ogawa Chiaki
• Inoguchi Kazuhiro

Classifications

• G01K1/12 Primary

  for preventing damage due to heat overloading · CPC title

• G01K7/02 Primary

  using thermoelectric elements, e.g. thermocouples · CPC title

• G01K7/22

  the element being a non-linear resistance, e.g. thermistor (G01K7/26 takes precedence) · CPC title

• H01C7/008

  Thermistors (H01C7/02 - H01C7/06 take precedence) · CPC title

• H01C1/148

  the terminals embracing or surrounding the resistive element (H01C1/142 takes precedence) · CPC title