JPH109970A - Temperature sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature sensor which omits a lead wire to be passed through the inside of a metal pipe, whose structure is simplified and in which the diameter of an metal pipe can be made small by a method in which one end of the external connecting terminal at a sensor element is connected electrically to the metal pipe and the metal pipe constitutes a part of a derivation wire. SOLUTION: The outside diameter of a metal pipe 3 is decided only by the wall thickness of the pipe 3, by the diameter of a lead wire 4b and by a gap required when the lead wire is inserted into the metal pipe 3. That is to say, it is decided in such a way that (the diameter of the metal pipe 3)>=(the diameter of the lead wire 4b)+2×(the wall thickness of the metal pipe 3)+(the insertion gap), and it has noting to do with the diameter of a sensor element 1 and with the wall thickness of an insulating tube. As a result, a temperature sensor can be miniaturized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a miniaturized temperature sensor.

[0002]

2. Description of the Related Art FIG. 1 shows the structure of a conventional temperature sensor.
As shown in FIG. 1, the temperature sensor includes a sensor element 1, external connection terminals 2a and 2b, a metal tube 3, lead wires 4a and 4b, and an insulating tube 5. That is, the sensor element 1
External connection terminals 2a, 2
b, the lead wires 4a and 4b are electrically connected and pulled out, the outside thereof is covered with the insulating tube 5, and the outside thereof is covered with the metal tube 3.

[0003]

The outer diameter of the metal tube which determines the size of the temperature sensor has the following five items. Since the dimensions satisfying these items are required, it is difficult to reduce the size. There was a problem.

The first point is the diameter of the sensor element 1, which is an element for detecting temperature.

The second point is that, since the lead wire is drawn out from both ends of the sensor element 1, it is necessary to turn out the lead wire 4a connected to the external connection terminal 2a at one end of the sensor element. This is the diameter of the lead wire 4a. The lead wires 4a and 4b are connected to the external connection terminals 2b.
It is necessary to use a coated wire to prevent electrical contact with the metal tube 3 and the metal tube 3.

The third point is that the insulating tube 5 must be covered in order to avoid contact between the sensor element 1 and the metal tube 3, and 2 × (thickness of the insulating tube 5) is required.

[0007] Fourth, in order to insert the insulating tube 5 covering the sensor element into the metal tube 3, it is necessary to provide a gap between the insulating tube 5 and the metal tube 3.

The fifth point is the thickness of the metal tube 3, which requires 2 × (the thickness of the metal tube 3).

Therefore, the equation for determining the diameter of the metal tube 3 is as follows. Diameter of metal tube 3 ≧ (diameter of sensor element 1) + (diameter of lead wire 4a) + 2 × (thickness of insulating tube 5) +
(Insertion gap) + 2 x (thickness of metal tube 3)

[0010]

In order to solve the above problem, in view of reducing the diameter of the metal tube, one end of an external connection terminal of the sensor element is electrically connected to the metal tube,
In addition, since the metal tube forms a part of the lead wire, the lead wire that passes through the inside of the metal tube is omitted, so that the structure can be simplified and the diameter of the metal tube can be reduced.

[0011]

FIG. 2 is a sectional view showing a temperature sensor according to a first embodiment of the present invention.
Generally, the diameter of the sensor element can be made smaller than the diameter of the metal tube. As is apparent from FIG. 2, the outer diameter of the metal tube 3 is determined only by the thickness of the metal tube 3, the diameter of the lead wire 4b, and the gap when the metal tube 3 is inserted into the metal tube 3. That is, (diameter of metal tube 3) ≧ (diameter of lead wire 4b) + 2 ×
(Thickness of the metal tube 3) + (insertion gap), which is not related to the diameter of the sensor element 1 and the thickness of the insulating tube 5, so that the temperature sensor can be downsized.

Specifically, in the present invention, the outer diameter φ0.
SUS304 with dimensions of 8mm, inner diameter φ0.3mm, length 30mm
A metal pipe having an external connection terminal 2a, 2b at one end of the metal pipe 3 having an outer diameter of 0.5 mm and a hole diameter of 0.3
An external connection terminal 2b, which is one end of a platinum temperature sensor element 1 having a size of 5 mm and a length of 2 mm, is electrically connected by applying a conductive paste 6. A lead wire 4b obtained by stripping the tip of a ceramic-coated electric wire having an outer diameter of 0.2 mm is fixed to the external connection terminal 2a, which is the other end of the sensor element 1, through the through hole of the sensor element 1 with a conductive paste 6. . In order to protect the sensor element 1, an epoxy resin 7 is applied very thinly to form an insulating film.

[0013]

Second Embodiment FIG. 3 is a sectional view of a temperature sensor according to a second embodiment of the present invention.
The sensor element 1 is electrically connected so that the center of the external connection terminal 2a at one end coincides with the center of the sensor element 1.
The lead wire 4b is electrically connected to the external connection terminal 2b at the other end of the metal tube 3 and inserted into the metal tube 3, and the external connection terminal 2a and the metal tube 3 are electrically connected. In this case, the diameter of the metal tube 3 is (diameter of the metal tube 3) ≧ (diameter of the sensor element 1) +2
× (thickness of metal tube) + 2 × (insertion gap), and the size can be reduced regardless of the thickness of the insulating tube 5 and the diameter of the lead wire 4a.

[0014]

Embodiment 3 and Embodiment 4 FIGS. 4 and 5 show a second embodiment of the present invention.
FIGS. 4 and 5 are cross-sectional views of a temperature sensor in which the distal end portion of the metal tube is processed into a shape into which an external connection terminal at one end is fitted in FIGS. A metal pipe machined into one end of the metal tube 3 so as to fit the external connection terminal is used.
Are arranged and fixed by the conductive paste 6, so that the sensor element 1 and the metal tube 3 can be easily positioned on the same center line.

[0015]

Embodiment 5 FIG. 6 is a sectional view of a temperature sensor according to one embodiment of the present invention in the scope of claim 3. In this figure, the metal tube 3 and the end of the lead wire 4a are electrically connected in order to draw out the lead wire 4a from the same direction as the lead wire 4b in the temperature sensor of FIG. As a result, a temperature sensor capable of extending the lead wire was obtained.

[0016]

As described above, according to the present invention, instead of simply arranging the sensor element inside the metal tube, the sensor element is directly electrically connected to the metal tube to serve as a lead wire. Accordingly, only one lead wire is required to pass through the through hole inside the metal tube, and the structure can be simplified, and as a result, a small temperature sensor can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a conventional temperature sensor.

FIG. 2 shows a first embodiment according to the present invention;
FIG. 3 is a cross-sectional view showing the temperature sensor of FIG.

FIG. 3 shows a second embodiment according to the first embodiment of the present invention;
FIG. 3 is a cross-sectional view showing the temperature sensor of FIG.

FIG. 4 shows a third embodiment according to the second aspect of the present invention.
FIG. 3 is a cross-sectional view showing the temperature sensor of FIG.

FIG. 5 is a fourth embodiment according to the second aspect of the present invention.
FIG. 3 is a cross-sectional view showing the temperature sensor of FIG.

FIG. 6 shows a fifth embodiment according to the third aspect of the present invention.
FIG. 3 is a cross-sectional view showing the temperature sensor of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sensor element 2a External connection terminal 2b External connection terminal 3 Metal tube 4a Lead wire 4b Lead wire 5 Insulation tube 6 Conductive paste 7 Epoxy resin

Claims (3)

[Claims] 1. A sensor element having at least two external connection terminals is disposed at a tip of a metal tube having a through hole therein, and one end of the external connection terminal is electrically connected to the metal tube. A temperature sensor wherein an end is electrically connected to a lead wire, and the lead wire is drawn out through a through hole inside the metal tube. 2. The temperature sensor according to claim 1, wherein the distal end of said metal tube is formed into a shape into which an external connection terminal at one of said ends is fitted. 3. The temperature sensor according to claim 1, wherein a lead wire other than the lead wire is electrically connected to a position other than the sensor element connection portion of the metal tube. Temperature sensor.