JPH11201832A - Temperature sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature sensor at low costs and having preferable characteristic as costs of the temperature sensor are very high since an output led-out lead wire is composed of a platinum wire in the temperature sensor using a thin film temperature detection element. SOLUTION: A temperature detection portion of a temperature sensor comprises a metal pipe 1; a ceramic substrate 2 which is inserted into the inside of the metal pipe 1 and is longer than the metal pipe 1 having a film-like temperature detection element 3 and a film-like electrode 4 fetching electrically an output of the temperature detection element 3; an inorganic filler material burying a gap between the metal pipe 1 and the ceramic substrate 2; and a protection cap 6 arranged at an end of the metal pipe 1 and protecting a portion having the temperature detection element 3 of the ceramic substrate 2. Thus, as an expensive platinum wire is not used for a lead wire, it is possible to attain the temperature sensor at low costs and having preferable characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a temperature sensor.

[0002]

2. Description of the Related Art Conventionally, among sensors for detecting various temperatures, a temperature sensor using a thin-film thermistor element as a temperature-sensitive element has been proposed, for example, in Japanese Patent Application No. 8-54601. FIG. 9 shows a schematic sectional view of such a temperature sensor. The temperature sensor element 51 is composed of a thin film ceramic sintered body formed on a substrate. Temperature sensor element 51
The element electrical resistance take-out part of is formed by a platinum film,
They are connected to lead wires 65 and 66 made of platinum. The lead wires 65 and 66 are arranged inside the tubular metal housing 63 in a state where they are insulated from each other by the electrically insulating glass 61 and 62. The tubular metal housing 63 is fixed to a flange 64. The temperature is electrically detected as a resistance value of the temperature sensor element 51.

[0003]

SUMMARY OF THE INVENTION Such a sensor is
In recent years, when an attempt is made to apply the present invention to an exhaust gas purification system of an automobile which is being studied for environmental protection, a good temperature sensor including characteristics and reliability can be constructed. The use of wires results in a significantly more costly temperature sensor. Since the platinum wire actually used for the temperature sensor was about 0.54 g,
Calculating from the platinum price as of July 1997 (about 1500 yen / g), it costs about 800 yen only for the value of platinum, and the conventional technique has a problem that the cost of the temperature sensor becomes extremely high.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a low-cost temperature sensor having good characteristics.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a metal pipe, a film-shaped temperature detecting element inserted inside the metal pipe, and an output of the temperature detecting element. A ceramic substrate having a film-like electrode to be taken out, a ceramic substrate longer than the metal pipe, an inorganic filler for filling a gap between the metal pipe and the ceramic substrate, and a temperature detection of the ceramic substrate provided at an end of the metal pipe. A configuration including a protective cap for protecting a portion having the element, or a metal pipe, and a film-shaped temperature detection element inserted into the metal pipe and electrically extracting an output of the temperature detection element and the temperature detection element. A ceramic substrate longer than the metal pipe having the electrodes described above, and the ceramics disposed at both ends of the metal pipe and inserted through the metal pipe. Those having a cap-shaped supporting member for fixing the plate, the arrangement comprising a protection cap for protecting the portion including the temperature detecting element of said ceramic substrate.

Thus, a low-cost temperature sensor having good characteristics can be constructed.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The invention according to claim 1 of the present invention is characterized in that a metal pipe is inserted inside the metal pipe,
A ceramic substrate longer than the metal pipe having a film-shaped temperature detection element and a film-shaped electrode for electrically extracting the output of the temperature detection element; an inorganic filler filling a gap between the metal pipe and the ceramic substrate; A protective cap disposed at an end of the metal pipe and protecting a portion of the ceramic substrate having the temperature detecting element, for forming a film-shaped electrode on the ceramic substrate longer than the metal pipe. The temperature sensor can be realized without using an expensive platinum wire.

According to a second aspect of the present invention, the inorganic filler comprises at least one component of alumina, zirconia, and silica. It has the effect that it can be fixed stably to the pipe.

According to a third aspect of the present invention, the inorganic filler has an L content.
Since i ₂ O is added and Li ₂ O suppresses foaming during curing of the inorganic filler, it has an effect that the ceramic substrate can be stably and accurately fixed to the metal pipe even at a high temperature.

[0010] According to a fourth aspect of the present invention, a metal pipe is provided.
A ceramic substrate longer than the metal pipe, which is inserted into the metal pipe and has a film-shaped temperature detecting element and a film-shaped electrode for electrically extracting an output of the temperature detecting element, and is disposed at both ends of the metal pipe. And a cap-shaped support member for fixing the ceramic substrate inserted into the metal pipe, and a protective cap for protecting a portion of the ceramic substrate having a temperature detecting element, wherein the film-shaped electrode is made of metal. Since the film is formed on a ceramic substrate longer than the pipe, a temperature sensor can be realized without using an expensive platinum wire.

According to a fifth aspect of the present invention, a hole is formed in the protective cap, and a temperature change around the temperature sensor is directly transmitted to the temperature detecting element through the hole. It has the effect that it can be realized.

According to a sixth aspect of the present invention, a cap-shaped support member is formed with a bottom, and a plurality of irregularities are provided on an inner peripheral wall of a hole provided on the bottom surface. Since the metal pipe is in contact with the ceramic substrate, the metal pipe and the ceramic substrate can be easily and reliably fixed.

According to a seventh aspect of the present invention, the cap-like supporting member and the protective cap are made of a nickel-chromium alloy, and have an effect of holding and protecting the ceramic substrate up to a high temperature.

According to the present invention, the support member and the protective cap provided at the end of the metal pipe are fixed to the metal pipe at the same time. Since both can be easily fixed, the cost can be reduced. It has an effect that a temperature sensor can be manufactured.

According to a ninth aspect of the present invention, the lead-out portion of the film-like electrode is soldered to the lead wire, and the soldered portion is molded with resin, so that the electrode and the lead wire can be easily connected. In addition, since the temperature sensor is completely sealed, a low-cost and highly reliable temperature sensor can be formed.

According to the tenth aspect of the present invention, since the resin is made of silicon or polyimide, and both of them are high heat resistant resins, they have an effect that a highly reliable temperature sensor can be formed.

According to the eleventh aspect of the present invention, since the lead wire is covered with a Teflon-based resin and is made of a high heat-resistant resin, it has an effect that a highly reliable temperature sensor can be constituted.

According to a twelfth aspect of the present invention, the film-shaped electrode is made of a platinum paste, and at least the portion to be soldered is only the glass-containing conductive paste, and the glass-containing conductive paste overlaps the platinum paste. It has an effect that high reliability of the connection portion can be secured by soldering on a glass-containing conductive paste having good solder erosion and tensile strength of the lead wire.

According to a thirteenth aspect of the present invention, the glass-containing conductive paste has a silver-palladium-based composition or a silver-palladium-platinum-based composition. Since it is good, it has an effect that high reliability of the connection portion can be secured.

According to a fourteenth aspect of the present invention, the temperature detecting element is formed of platinum or a thermistor, and has an effect of being able to measure with high accuracy up to a high temperature.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 is a schematic sectional view of a temperature sensor according to a first embodiment of the present invention, FIG. 2 is a configuration diagram of a temperature detecting portion of FIG. 1, and FIG. The sectional views after assembly are shown. 1 to 3,
The same parts are given the same numbers. Reference numeral 1 denotes a metal pipe made of heat-resistant stainless steel having an outer diameter of 3 mm and a thickness of 0.4 mm, into which an alumina ceramic substrate 2 longer than the metal pipe 1 is inserted. A temperature detecting element 3 in the form of a film is formed on the tip of the ceramic substrate 2 by a CVD method. Here, a thermistor made of a composite oxide of Al, Cr and Fe was used as the temperature detecting element. On the surface of the temperature detecting element 3, a pair of film-shaped electrodes 4 for electrically detecting the resistance value is formed. Here, the electrode 4 was formed by printing and firing a platinum paste. An enlarged view of the electrode 4 is shown in FIG. The portion from which the electrode is taken out, that is, the portion to be soldered, is formed by printing and firing only the silver-palladium-based glass-containing conductive paste 4a. The electrode 4 made of platinum paste and the glass-containing conductive paste 4a have an overlapping portion 4b. The gap between the metal pipe 1 and the ceramic substrate 2 is filled with an inorganic filler 5. The inorganic filler 5 is mainly composed of alumina,
It is formed by injecting a paste-like filler containing silica and Li ₂ O into a gap between the metal pipe 1 and the ceramic substrate 2 by a prescribed amount with a dispenser, and then hardening at 150 ° C. A protection cap 6 made of a nickel-chromium alloy for protecting the temperature detection element 3 is inserted into the metal pipe 1 at a portion of the ceramic substrate 2 having the temperature detection element 3 and is caulked and welded. The protective cap 6 has two holes 6a as shown in FIG.

The glass-containing conductive paste 4a is connected by soldering to a lead wire 7 covered with a Teflon-based resin, and the entire soldered portion is molded with a polyimide resin 8 so that a part of the lead wire 7 is covered. I have. This state is shown in FIG. Further, the lead wire 7 is fixed by an insulator 9 made of glass fiber reinforced resin. Reference numeral 10 denotes a nut for attaching a temperature sensor provided on the outer periphery of the metal pipe 1.

The temperature was detected electrically as a change in the resistance value of the temperature detecting element 3 depending on the temperature.

A temperature sensor having such a configuration was prototyped and its output characteristics were evaluated. As a result, it was confirmed that not only a change in resistance value due to temperature, which is a basic characteristic, but also a reliability equivalent to that of the conventional example could be obtained. Further, in response, a speedup of 30 to 40% as compared with the conventional example was realized. This is because the temperature change is directly transmitted to the temperature detecting element 3 by providing the hole 6 a in the protective cap 6. Also,
Regarding cost, about 0.01 g of platinum paste is used, so the price of platinum paste (about 3500 yen / g)
Approximately 35 yen is calculated from the conventional platinum wire (about 8 yen).
00 yen), which is a twentieth or less of the cost.

In the present embodiment, the inorganic filler 5 is composed mainly of alumina and contains silica and Li ₂ O, but may be composed of alumina or silica alone or zirconia. Also, it could have been composed of a plurality of these. This is because all of them have good electrical insulation under a high temperature atmosphere,
Was also good. Further, the reason why Li ₂ O is added to the inorganic filler 5 is that foaming is suppressed at the time of curing of the filler and the filler can be densely filled.

Although the resin 8 is made of polyimide in the present embodiment, it may be made of silicon. In the case of silicon, stress due to the difference in thermal expansion between the ceramic substrate 2 and the lead wire 7 can be reduced, and the resistance to thermal shock is further enhanced than when polyimide is used.

Further, although the silver-palladium-based glass-containing conductive paste 4a was used, the same characteristics were obtained with the silver-palladium-platinum-based conductive paste. Further, the temperature detection element 3 uses a thermistor, but this may be platinum. In this case, although the rate of change in resistance due to temperature is smaller than that of the thermistor, since the film can be formed simultaneously with the electrode 4, there is an advantage that the number of steps is reduced, and an appropriate temperature detecting element may be selected according to the application.

From the above, good output characteristics and
A low-cost temperature sensor was realized.

(Embodiment 2) The temperature sensor according to the second embodiment of the present invention has many structural parts that are the same as those of the first embodiment. Omitted. That is, the feature of the present embodiment is that the ceramic substrate 2 is not fixed with the inorganic filler 5 but is fixed with a cap-shaped support member. Hereinafter, the temperature sensor actually manufactured in this manner will be described.

FIG. 6 is an exploded perspective view of the temperature detecting portion in FIG. 1, FIG. 7 is a perspective view when the temperature detecting portion is assembled, and FIG. 8 is a sectional view of FIG. Reference numeral 11 denotes a cap-shaped support member made of a nickel-chromium alloy. As shown in FIG. 6, the support member 11 is formed into a bottomed shape by press working, and a plurality of holes 12 having a plurality of irregularities are formed on the bottom surface. This support member 11 was inserted into both ends of the metal pipe 1, and was fixed by caulking and welding. At this time, the protection cap 6 was inserted into the outer periphery of one of the support members 11, and the two were simultaneously caulked and welded. The ceramic substrate 2 is inserted into the concave-convex hole 12 formed in the support member 11 as shown in FIG.
Here, a concave-convex hole 12 is formed in the support member 11. This is because the ceramic substrate 2 can be inserted from any direction, so that the productivity is improved. Due to the difference in thermal expansion of the ceramic substrate 2, the ceramic substrate 2 can freely extend in the substrate length direction.
Since any of the irregularities of the support member 11 is always in contact with the ceramic substrate 2 in the thickness and width directions of the substrate, the ceramic substrate 2 can be held against vibration. That is, the ceramic substrate 2 has a feature that it can be fixed in such a manner that it can move in the substrate length direction and cannot move in the substrate thickness and width directions.

The output characteristics of the temperature sensor manufactured in this manner exhibited good output characteristics and reliability, as in the first embodiment, and it was confirmed that high-speed response could be realized. Also, as in the first embodiment, expensive platinum wires are not used as in the first embodiment, so that the cost can be reduced.

The present embodiment is characterized in that no filling step and curing step are required because no inorganic filler is used as compared with the first embodiment.

With the above configuration, a low-cost temperature sensor having good output characteristics can be realized.

[0034]

As is apparent from the above description, according to the present invention, the metal pipe, the film-shaped temperature detecting element inserted into the metal pipe, and the output of the temperature detecting element are electrically connected. A ceramic substrate having a film-like electrode to be taken out, a ceramic substrate longer than the metal pipe; an inorganic filler filling a gap between the metal pipe and the ceramic substrate; and a temperature detecting element for the ceramic substrate disposed at an end of the metal pipe. Or a protective cap that protects the portion having, or a metal pipe, and a film-shaped temperature detecting element inserted into the metal pipe and electrically extracting the output of the film-shaped temperature detecting element and the temperature detecting element. A ceramic substrate longer than the metal pipe having electrodes; and the ceramic substrate disposed at both ends of the metal pipe and inserted through the metal pipe. A cap-shaped supporting member for fixing,
With a configuration having a protective cap for protecting a portion of the ceramic substrate having a temperature detection element,
Low cost, because expensive platinum wire is not used for the lead wire
In addition, an advantageous effect that a temperature sensor having good characteristics can be provided can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a temperature sensor according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a temperature detecting portion of the temperature sensor.

FIG. 3 is a sectional view of a temperature detecting portion of the temperature sensor.

FIG. 4 is an enlarged view of an electrode portion of the temperature sensor.

FIG. 5 is a perspective view of an electrode part of the temperature sensor.

FIG. 6 is an exploded perspective view of a temperature detecting portion of a temperature sensor according to a second embodiment of the present invention.

FIG. 7 is a perspective view of a temperature detecting portion of the temperature sensor.

FIG. 8 is a sectional view of a temperature detecting portion of the temperature sensor.

FIG. 9 is a schematic sectional view of a conventional temperature sensor.

[Explanation of symbols]

 Reference Signs List 1 metal pipe 2 ceramic substrate 3 temperature detecting element 4 electrode 4a glass-containing conductive paste 4b overlapping portion 5 inorganic filler 6 protective cap 7, 65, 66 lead wire 8 resin 9 insulator 10 nut 11 support member 12 uneven hole 51 Temperature sensor element 61, 62 Electrically insulating glass 63 Tubular metal housing 64 Flange

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kiyoshi Saito 1006 Kazuma Kadoma, Kadoma City, Osaka Inside Matsushita Electric Industrial Co., Ltd.

Claims (14)

[Claims] A ceramic substrate inserted into the metal pipe and having a film-shaped temperature detecting element and a film-shaped electrode for electrically extracting an output of the temperature detecting element, the ceramic substrate being longer than the metal pipe; A temperature sensor comprising: an inorganic filler filling a gap between the metal pipe and the ceramic substrate; and a protection cap disposed at an end of the metal pipe and protecting a portion of the ceramic substrate having a temperature detecting element. 2. The temperature sensor according to claim 1, wherein the inorganic filler comprises at least one component of alumina, zirconia, and silica. 3. The temperature sensor according to claim ₂ , wherein Li ₂ O is added to the inorganic filler. 4. A ceramic substrate longer than the metal pipe having a metal pipe, a film-shaped temperature detecting element inserted into the metal pipe, and a film-shaped electrode for electrically extracting an output of the temperature detecting element. A cap-shaped support member disposed at both ends of the metal pipe and fixing the ceramic substrate inserted through the metal pipe; and a protective cap for protecting a portion of the ceramic substrate having a temperature detecting element. Sensor. 5. The temperature sensor according to claim 1, wherein a hole is provided in the protective cap. 6. The temperature sensor according to claim 4, wherein the cap-shaped support member is formed with a bottom, and a plurality of irregularities are provided on an inner peripheral wall of a hole provided on the bottom surface. 7. The temperature sensor according to claim 1, wherein the cap-shaped support member and the protective cap are made of a nickel-chromium alloy. 8. The temperature sensor according to claim 4, wherein the support member and the protection cap provided at the end of the metal pipe are fixed to the metal pipe at the same time. 9. The temperature sensor according to claim 1, wherein a portion where the film-shaped electrode is taken out is soldered to a lead wire, and the soldered portion is molded with a resin. 10. The temperature sensor according to claim 9, wherein the resin is made of silicon or polyimide. 11. The temperature sensor according to claim 9, wherein the lead wire is covered with a Teflon-based resin. 12. A film-like electrode comprising a platinum paste,
The temperature sensor according to claim 9, wherein at least a portion to be soldered is only the glass-containing conductive paste, and the glass-containing conductive paste is provided so as to overlap the platinum paste. 13. The temperature sensor according to claim 12, wherein the glass-containing conductive paste has a silver-palladium-based composition or a silver-palladium-platinum-based composition. 14. The temperature sensor according to claim 1, wherein the temperature detection element is platinum or a thermistor.