JPH10239162A - Temperature-detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to suppress the deterioration of insulation property by using Al2 O3 for an insulator constituting the double-core pipe became Cr2 O3 that is generated on the surface inside a metal cap and is scattered into an inner space does not react with Al2 O3 even if it is adhered to the edge part of an insulator being made of Al2 O3 of a double-core pipe. SOLUTION: The edge part of a metal pipe 5 is inserted into the opening of a metal cap 1 by approximately 3mm, the cap 1 is tentatively fixed by caulking a site that is approximately 3mm from the opening edge in a circumferential shape, and further a seam melting machining is performed in a circumferential shape at a position that is approximately 1.5mm from the open edge of the cap 1 by laser welding 6, thus securing the airtightness of the cap 1. The material of the cap 1 is thinned up to approximately 0.2-0.3mm to meet pyrogenic response performance, thus securing a durability for 1,000 deg.C heat resistance and heat cycle. By using Al2 O3 for the insulator 4 of a double-core pipe 12 regarding the material of the cap 1, the remarkable reduction in an insulation resistance at a high temperature can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature detecting device used for detecting temperatures in various places, and more particularly to a system for purifying an exhaust gas of an automobile which requires a heat resistance of 1000.degree. This is useful for detecting the temperature inside the converter.

[0002]

2. Description of the Related Art In recent years, an exhaust gas purifying apparatus for an automobile, that is, a temperature detecting apparatus used for detecting a temperature inside a catalytic converter, has a heat resistance of 1000 ° C. and a conventional 900 ° C.
In addition to durability against heat cycles between room temperature and normal temperature, the need for early confirmation of the operation of the purification system requires improvement in thermal response performance.

[0003] A conventional temperature detecting device will be described below. FIG. 5 is a half sectional front view of a conventional temperature detecting device.
As shown in FIG. 5, in the conventional temperature detecting device, a metal tube 25 is arranged around the whole of two metal wires 23 except for both ends, and an insulator made of MgO is provided between the metal wire 23 and the metal tube 25. 24, and a bottomed cylindrical metal cap 21 made of a Cr-containing metal attached to an end of the two-core tube 26 so as to house the temperature detecting element 22.
It was the composition provided with.

[0004]

However, in the above-mentioned conventional configuration, the diameter of the two-core tube 26 is reduced to a diameter of 3.5 mm or less in order to ensure high thermal response, and the thickness of the metal cap 21 is reduced. Is converted to Mg used as an insulating material.
The insulation distance of the insulator 24 of O, that is, the insulation distance of the metal tube 25 with respect to the metal wire 23 forming the two-core tube 26 is 0.5 mm
If the metal cap 21 is left continuously at a high temperature, Cr ₂ O ₃ generated on the surface of the metal cap 21 scatters inside the metal cap 21, and the end of the insulator 24 of the two-core tube 26. Of MgCr ₂ as a compound
The generation of O ₄ has a problem that the insulation resistance between the metal wire 23 and the metal tube 25 of the two-core tube 26 is significantly reduced.

An object of the present invention is to provide a temperature detecting device capable of high thermal response, heat resistance at 1000 ° C., and heat cycle resistance without impairing insulation performance.

[0006]

The temperature detecting device of the present invention uses Al ₂ O ₃ as an insulator of a two-core tube.

According to the present invention, the absolute construction of the two-core tube is provided.
Al on the edge_TwoO_ThreeBy using the table inside the metal cap
Generated on the surface and scatters into the space inside the metal cap
Cr _TwoO_ThreeIs a two-core tube Al_TwoO_ThreeDew on the end of the insulator consisting of
No reaction occurs even if it adheres to the protruding part, suppressing the deterioration of insulation performance.
Can be controlled.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention
Is to place a metal tube around the two metal wires except for both ends,
Al is placed between the metal tube and the metal wire._TwoO_ThreeInsulation consisting of
The two-core tube filled with the body and fixed, and the two-core tube
A temperature sensing element connected to one end of a metal wire
At the end of the two-core tube so as to house the temperature detecting element.
And a bottomed cylindrical metal cap made of a Cr-containing alloy
A temperature detecting device comprising: the metal tube and the metal wire;
Al to the insulator between_TwoO_ThreeThe use of the metal
Empty inside the metal cap generated on the surface inside the cap
Cr scattering between_TwoO_ThreeIs Al_TwoO_ThreeExposed part of insulator end
MgCr as in the conventional temperature detector _TwoO_Four
Compounds are no longer generated, and the gold constituting the two-core tube
It is possible to suppress the decrease in insulation resistance between the metal wire and the metal tube.
it can.

According to a second aspect of the present invention, there is provided a temperature detecting apparatus using a Ni-Cr alloy having a Cr content of 19 wt% or more and 30 wt% or less for a metal cap, and a third aspect of the present invention. The invention of NCH1 whose material is standardized in JIS C 2502 as a metal cap,
NCF601, AS specified in JIS G4901
This is a temperature detector characterized by being one of NCF617 standardized in TMB 166. It is suitable for thinning of a two-core tube and thinning of a metal cap. Durability and high thermal response performance can be ensured.

[0010] According to a fourth aspect of the present invention, the two metal wires have a Ni content of 19 wt% or more and 30 wt% or less.
And a temperature detecting device using a Cr alloy.
In the invention described in (1), the material of the two metal wires is JI
NCH1, JIS G specified in SC 2502
NCF601, ASTM B1 specified in 4901
A temperature detector that is one of the NCF617 standardized in No.66, and is suitable for thinning of the metal wire accompanying the thinning of the two-core tube, heat resistance at 1000 ° C, durability to heat cycles, and high thermal response. Performance can be ensured.

According to a sixth aspect of the present invention, there is provided a temperature detecting device in which the whole of the two-core tube is subjected to a heat treatment at a temperature of 900 ° C. or more before attaching the metal cap to the two-core tube.
In other words, by performing a heat treatment on the metal wire and the metal tube in advance and forming an oxide film on the surface, the oxidation of the surface of the metal wire and the metal tube of the two-core tube when the temperature detecting device is exposed to a high temperature. It is possible to prevent the oxygen deficiency state inside the metal cap from adversely affecting the temperature detecting element, and to ensure heat resistance of 1000 ° C.

The invention according to claim 7 is a temperature detecting device in which the entire metal cap is subjected to a heat treatment at a temperature of 900 ° C. or more before being attached to the two-core tube. By forming an oxide film on the surface, the oxygen deficiency inside the metal cap due to oxidation of the surface of the metal cap when the temperature detection device is exposed to a high temperature adversely affects the temperature detection element. Prevent 1
000 ° C. heat resistance can be secured.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a half sectional front view of a temperature detecting device according to an embodiment of the present invention.
FIG. 2 is an enlarged sectional view thereof. FIGS. 3 and 4 are a top view and a front view, respectively, of the temperature detecting element used in the temperature detecting device according to the present embodiment.

In FIG. 1, 1 is 0.2 to 0.3 in thickness.
mm with a bottomed cylindrical metal cap made of NCH1 standardized to JIS C 2502, the tip side of which is closed,
The rear end side is open. A temperature detecting element 2 is housed inside the tip of the metal cap 1 as shown in FIG. As shown in FIGS.
Electrode 2a consisting of a tubular platinum pipe and Al ₂ O ₃ , C
It is composed of a columnar NTC thermistor 2b composed of r ₂ O ₃ and Fe ₂ O ₃ components. In the temperature detecting element 2, Ni-
A 0.3 mm diameter metal wire 3 made of a Cr alloy penetrates and is welded and electrically connected at the end of an electrode 2a made of a platinum pipe as shown in FIG.

As shown in FIG. 1, the entirety of the two metal wires 3 except for both ends is fixed by an insulator 4 made of Al ₂ O ₃ , and furthermore, a metal tube of SUS310S having a diameter of 3.15 mm is formed around the insulator. 5 covered. Here, the two metal wires 3, the insulator 4, the metal tube 5, and the like constitute a two-core tube 12.

Next, the end of the metal tube 5 is inserted into the opening of the metal cap 1 by about 3 mm.
Is temporarily fixed by caulking a portion of about 3 mm from the opening end into a circumferential shape, and is further circumferentially formed by laser welding 6 at a position about 1.5 mm from the opening end of the metal cap 1. Seam welding is performed to ensure airtightness inside the metal cap 1.

Further, a lead wire 7 is electrically connected to each of the other ends of the metal wires 3 of the two-core tube 12 so that an electric signal can be taken out to the outside. Rubber material 8 made of cylindrical silicon having two through holes
Has been penetrated. Further, the rubber material 8 is inserted into a pipe-shaped metal case 9, and the outer periphery of one end of the metal case 9 is plastically deformed inward to be in close contact with the internal rubber material 8, so that the airtightness inside the temperature detecting device is improved. Is secured. The other end of the metal case 9 is arranged on the outer peripheral portion of the metal tube 5 of the two-core tube 12, and is fixed and sealed by laser welding 10.

The metal cap 1 and the two-core tube 12 are
Heat treatment is performed in advance at a temperature of 900 to 1100 ° C. to form an oxide film layer.

Here, the material of the metal cap 1 is reduced in thickness to 0.2 to 0.3 mm in order to satisfy the high thermal response performance. Durability to heat cycles can be ensured. In addition, NC specified by JIS G 4901 as a Ni-Cr alloy or an alloy of Fe-Ni-Cr type composition
F601, NCF6 specified in ASTM B166
17 are available.

The material of the two metal wires 3 is reduced in diameter to 0.2 to 0.3 mm in order to satisfy the high thermal response performance. Heat resistance and durability against heat cycles can be ensured. Other NCH standardized in JIS C 2502
1 and Fe-Ni-Cr based alloys as JIS G4
NCF601, ASTM B 16
6 can be used. When such a material is oxidized in the air, its surface becomes Cr ₂ O ₃
An oxide film mainly composed of, for example, enhances heat resistance, and can be used even at a high temperature of 1000 ° C. or in a thermal cycle environment even if the oxide film has a small thickness and a small diameter. is there.

Alloy of Ni-Cr System Composition and Fe-Ni
In the alloy of -Cr-based composition (NCF based composition), when the content of Cr is more than 19 wt%, although components of the oxide film to be the product has Cr ₂ O ₃ as the main, is less than 19 wt% NiO-Cr ₂ O ₃ and NiO-Cr ₂ O ₃ -Fe ₂
Since O ₃ is mixed, the heat resistance and the heat cycle resistance to the reduction in thickness and diameter are reduced, and the performance cannot be secured. Further, in the alloy having the Ni-Cr composition, the Cr content is 3%.
When the content is 0 wt% or more, the oxidation resistance is excellent, but the mechanical strength at high temperature is weakened, and the practical use is generally up to 30 wt%.

Next, a 1000 ° C. heat resistance test was performed on the conventional temperature detector in which the insulator of the two-core tube was MgO and the temperature detector according to the embodiment of the present invention. The results are shown in (Table 1). Table 2 shows the results of a heat cycle test of the conventional temperature detecting device and the temperature detecting device according to the embodiment of the present invention.

[0023]

[Table 1]

[0024]

[Table 2]

Further, Table 3 shows the results of the resistance value fluctuations in the embodiment of the present invention in which the two-core tube 12 was subjected to the heat treatment and the conventional example in the standing test at 1000 ° C. Further, (Table 4) shows the results of the resistance value fluctuation in the embodiment of the present invention in which the metal cap 1 was subjected to the heat treatment and the conventional example in the 1000 ° C. standing test.

[0026]

[Table 3]

[0027]

[Table 4]

In Table 1, the insulation resistance value is DC25.
Insulation value between metal tube and metal wire when V is applied, 850 ° C
3 shows the insulation resistance value at the temperature of FIG. Regarding the performance, the insulation value for determination was set to 100 kΩ, which was 300 times or more the resistance value (300Ω) of the temperature detection element used in the embodiment of the present invention, that is, the NTC thermistor at a temperature of 850 ° C.

In Table 2, as a test condition of the thermal cycle test, a process in which the temperature detecting device is exposed to 900 ° C. for 5 minutes and then exposed to room temperature (room temperature) for 5 minutes is defined as one cycle. This was repeated 10,000 cycles. As the evaluation, the progress of oxidation of the metal wire after the test was judged from the appearance.

In Tables 3 and 4, the rate of change in resistance refers to the rate of change in resistance of the temperature detector before and after the heat resistance test at 1000 ° C., and indicates the rate of change of resistance at 850 ° C. . Also, the performance was set within ± 5%.

According to Table 1, in the case of the present embodiment, the insulator 4 of the two-core tube 12 is made of A in the material of each metal cap 1.
It has been found that by setting to l ₂ O ₃ , a remarkable decrease in the insulation resistance value at a high temperature can be suppressed.

As shown in Table 2, in the case of the present embodiment, no remarkable progress of oxidation of the material of each metal wire 3 was observed even in a severe thermal cycle, and a structure having high thermal mechanical strength was obtained. Was confirmed.

From Table 3, it was confirmed that in the case of the present embodiment, by setting the heat treatment temperature of the two-core tube 12 to 900 ° C. or more, a remarkable increase in the resistance value at a high temperature can be suppressed.

From Table 4, it was confirmed that in the case of the present embodiment, by setting the heat treatment temperature of the metal cap to 900 ° C. or higher, a remarkable increase in the resistance value at a high temperature can be suppressed.

In this embodiment, the materials of the metal cap 1 and the metal wire 3 are NCH1, Ni--Cr alloy, NC
Although F601 and NCF617 have been studied, it goes without saying that this object can also be achieved mainly for a metal material that mainly forms an oxide film of Cr ₂ O ₃ .

[0036]

As described above, the present invention impairs insulation performance by using a Cr-based alloy material for the metal cap and the metal wire and using Al ₂ O ₃ for the insulator of the two-core tube. Thus, an excellent temperature detecting device having high thermal response, high heat resistance and heat cycle performance can be realized without the need.

Further, the two-core tube and the metal cap are previously set to 9
By performing the heat treatment at a temperature of 00 ° C. or more, the fluctuation of the resistance value at a high temperature can be suppressed small, and an excellent temperature detecting device having high heat resistance can be realized.

[Brief description of the drawings]

FIG. 1 is a half sectional front view of a temperature detecting device according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of the same.

FIG. 3 is a top view of the temperature detecting element according to the embodiment of the present invention.

FIG. 4 is a front view of the same.

FIG. 5 is a half sectional front view of a conventional temperature detecting device.

[Explanation of symbols]

1 metal cap 2 temperature detecting element 3 metal wire 4 Al ₂ O ₃ insulator 5 metal tube 12 two-core tube

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Tamai 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (7)

[Claims] 1. A two-core tube in which a metal tube is disposed around the two metal wires except for both ends thereof, an insulator is filled between the metal tube and the metal wire and fixed, and the two-core tube is fixed. A temperature detecting element connected to one end of a metal wire constituting a tube, and a bottomed cylindrical metal made of a Cr-containing alloy attached to an end of the two-core tube so as to house the temperature detecting element. Equipped with a cap,
A temperature detecting device, wherein the insulator is Al ₂ O ₃ . 2. The temperature detecting device according to claim 1, wherein the metal cap is a Ni—Cr alloy, and the Cr content is 19 wt% or more and 30 wt% or less. 3. The metal cap is made of JIS C
NCH1 specified in 2502, JIS G 490
The temperature detection device according to claim 1, wherein the temperature detection device is one of NCF 601 specified by No. 1 and NCF 617 specified by ASTM B166. 4. The temperature detecting device according to claim 1, wherein the two metal wires are a Ni—Cr alloy and have a Cr content of 19 wt% or more and 30 wt% or less. 5. The material of the two metal wires is JIS C
NCH1 specified in 2502, JIS G 490
The temperature detection device according to claim 1, wherein the temperature detection device is one of NCF 601 specified by No. 1 and NCF 617 specified by ASTM B166. 6. The temperature detecting device according to claim 1, wherein the whole of the two-core tube is heat-treated at a temperature of 900 ° C. or more and 1200 ° C. or less before attaching the metal cap. 7. The temperature detecting device according to claim 1, wherein the entire metal cap is heat-treated at a temperature of 900 ° C. or more and 1200 ° C. or less before being attached to the two-core tube.