# US 2009/0268779 A1 · Temperature sensor element and method of manufacturing the same

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- Number: US 2009/0268779 A1
- Document ID: US20090268779A1
- Status: Published application
- Kind: A1
- Application number: 12/111,405
- Filed: 2008-04-29
- Published: 2009-10-29
- Earliest claimed: 2008-04-29
- Assignees: Ngk Spark Plug Co., Ltd.
- Inventors: Nobuyuki Hotta; Kazushige Ohbayashi
- Web page: https://patentgrep.com/patent/US20090268779A1

## CPC

- G01K 7/04: the object to be measured not forming one of the thermoelectric materials
- G01K 1/10: for preventing chemical attack
- G01K 1/18: for reducing thermal inertia
- G01K 2205/04: for measuring exhaust gas temperature
- G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00)

## Abstract

A temperature sensor element 10 has a reduced thermal conduction path from a measurement object to a sensitive end portion 22 of a thermocouple 21 and a high-dense insulating ceramic base body 20. Since the temperature sensor element 10 has excellent thermal conductivity from the measurement object to the sensitive end portion 22 of the thermocouple 21, it is also excellent in responsiveness at the time of temperature detection. Further, corrosion and material deterioration of the thermocouple 21 is unlikely to occur because the thermocouple 21 does not directly contact the measurement object (exhaust gas). As a result, the temperature sensor element 10 exhibits excellent durability. Therefore, the temperature sensor element 10 exhibits a good responsiveness at the time of temperature detection as well as excellent durability.

## Claims

### Claim 1

A temperature sensor element, comprising:
an elongated sintered body extending in an axial direction, said sintered body having an outer surface for exposure to a matter to be measured, said sintered body being formed by sintering insulating ceramic material;
a sensitive member embedded in the sintered body; and
a signal output portion formed on a rear end side of the sintered body for outputting an electric signal received from the sensitive member to the outside,
wherein the sensitive member is comprised of a thermocouple embedded in the sintered body in a state that a detection end portion is disposed on a front end side of the sintered body in the axial direction, and
wherein the sintered body is in contact with the detection end portion of the sensitive member and is a dense material which has gas impermeability in a region from an outer surface of the sintered body to the sensitive member.

### Claim 2 (depends on 1)

A temperature sensor element according to the claim 1,
wherein the sintered body has porosity of 10% or less in a region from a front end thereof to a portion where the detection end portion is embedded in the axial direction.

### Claim 3 (depends on 1)

A temperature sensor element according to the claim 1,
wherein the thermocouple is comprised of tungsten or an alloy containing tungsten as a principal component.

### Claim 4 (depends on 1)

A temperature sensor element according to the claim 1,
wherein the thermocouple includes at least an alloy-made negative leg containing tungsten and rhenium where the rhenium content is greater than that of a positive leg.

### Claim 5 (depends on 1)

A temperature sensor element according to the claim 1,
wherein the sintered body is made of insulating ceramic containing silicon nitride or alumina as a principal component.

### Claim 6 (depends on 1)

A temperature sensor element according to the claim 1,
wherein the sintered body has a configuration that, in the cross section perpendicular to the axial direction, a cross-sectional area of a portion where the detection end portion of the thermocouple is embedded is smaller than that of a portion where the signal output portion of the thermocouple is formed.

### Claim 7 (depends on 1)

A temperature sensor element according to the claim 1,
wherein, in the sintered body, a portion where the detection end portion of the thermocouple is embedded assuming a plate-like shape in the cross-section perpendicular to the axial direction.

### Claim 8

A method for manufacturing a temperature sensor element, comprising:
a lengthy sintered body extending in an axial direction and made of insulating ceramic;
a thermocouple embedded in the sintered body; and
a signal output portion outputting an electric signal to the outside according to an electromotive force of the thermocouple,
the method comprising, the steps of:
forming an unsintered body made of insulating ceramic before firing in which the thermocouple is embedded; and
forming a dense sintered body which has gas impermeability in a region from an outer surface of the sintered body to the thermocouple.