Temperature sensor

Patent metadata

Field	Value
Publication number	US-9752936-B2
Application number	US-201514748423-A
Country	US
Kind code	B2
Filing date	Jun 24, 2015
Priority date	Jun 25, 2014
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

In a temperature sensor, two seal members seal the open opposite ends of a cladding member (a forward end and a rear end), so that water absorption by an insulator of a sheath member can be restrained. The seal members are formed to have an insulation resistance equal to that of a conductor-fixing material. Therefore, even when the temperature sensor is used in a high-temperature environment, the insulation performance of the seal members does not become lower than the insulation performance of the conductor-fixing material, so that the formation of a leakage current path can be suppressed. According to the temperature sensor, the electrical property of a temperature sensitive element can be sensed accurately, and a reduction in the accuracy of temperature sensing can be restrained.

First claim

What is claimed is:

1. A temperature sensor comprising:
a temperature sensitive element having an electrical property that changes with temperature;
a sheath member including at least one conductor extending in a lengthwise direction of the temperature sensor and is electrically connected to the temperature sensitive element directly or through another member, an insulator formed of an insulating material and surrounding the at least one conductor, a metallic cladding member covering the insulator and open at opposite ends in the lengthwise direction, and seal members sealing the open opposite ends of the metallic cladding member with the at least one conductor extending outward from the metallic cladding member through the seal members; and
a covering member formed mainly of glass and covering a junction between the at least one conductor and the temperature sensitive element or a junction between the another member and the temperature sensitive element,
wherein:
an electric resistance of the temperature sensitive element increases with the temperature, and
an insulation resistance of the seal members is equal to or greater than an insulation resistance of the covering member.

2. A temperature sensor according to claim 1 , wherein the insulator of the sheath member is formed of magnesia (MgO).

3. A temperature sensor according to claim 1 , wherein the seal members of the sheath member are formed mainly of glass.

4. A temperature sensor according to claim 1 , further comprising a mounting member supporting the sheath member and including a contact surface for contacting an external member,
wherein,
in the lengthwise direction of the temperature sensor, a side on which the temperature sensitive element is disposed is defined as a forward end side and a side opposite the forward end side is defined as a rear end side,
the mounting member holds the sheath member such that a forward end of the metallic cladding member is disposed forward of the contact surface of the mounting member and that a rear end of the metallic cladding member is disposed rearward of the contact surface of the mounting member,
the seal members include a forward seal member disposed at the forward end of the metallic cladding member and a rear seal member disposed at the rear end of the metallic cladding member, and
an insulation resistance of the forward seal member is equal to or greater than an insulation resistance of the rear seal member.

Assignees

• Ngk Spark Plug Co

Inventors

• Nakanishi Hiroaki
• Oya Seiji

Classifications

• G01K2205/04

  for measuring exhaust gas temperature · CPC title

• G01K1/08 Primary

  Protective devices, e.g. casings · CPC title