JP2002022555A - Temperature sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature sensor with excellent thermal responsiveness used to measure the temperature of cooling water or the like for automobile. SOLUTION: A metallic body 7 is interposed between a case 1 of the temperature sensor and a thermistor element 2. The thermistor element 2 is made to abut to an inner circumferential surface of the case 1 by means of the metallic body 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature sensor for measuring the temperature of cooling water or the like of an automobile.

[0002]

2. Description of the Related Art In a conventional temperature sensor, a thermistor element is disposed inside a metal case having one end opened, and the opening of the metal case is sealed with a coupler. Was filled with silicone oil.

[0003]

However, silicon oil has a high specific heat, and since the silicon oil having a high specific heat is interposed between the sensor element and the metal case, it becomes difficult for external heat to be transmitted to the thermistor element. The thermal response of the temperature sensor was low.

Accordingly, the present invention is to solve such a problem and to provide a temperature sensor having excellent thermal response.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a case having a one-end opening made of metal, a thermistor element disposed in the case, and And a terminal having one end connected to the thermistor element and the other end led out to the outside, and the thermistor element is a temperature sensor brought into contact with the case via a metal body. Thus, the thermal conductivity between the thermistor element and the case is increased, and the thermal response of the temperature sensor can be improved.

According to a second aspect of the present invention, in the temperature sensor according to the first aspect of the present invention, the metal body is disposed so as to cover substantially the entire surface of the thermistor element. By arranging, the contact area with the thermistor element is increased and the heat conduction efficiency can be increased.

According to a third aspect of the present invention, there is provided the temperature sensor according to the first aspect, wherein the coupler is press-fixed to the opening of the case and an elastic body is interposed between the coupler and the case. In a temperature sensor in which a metal body is interposed between the thermistor element and the case, the elastic body is elastically deformed when the coupler is pressed against the case, so that the hermeticity of the inside of the case at the contact portion can be improved.

According to a fourth aspect of the present invention, there is provided a temperature sensor according to the third aspect, wherein the elastic body is formed of nitrile rubber or ethylene propylene rubber, wherein the elastic body is formed of nitrile rubber or ethylene propylene rubber. This can further enhance the hermeticity inside the case.

According to a fifth aspect of the present invention, there is provided a temperature sensor according to the third aspect, wherein a washer made of metal is interposed between the coupler and the elastic body, wherein the temperature sensor is made of metal between the elastic body and the coupler. By interposing the washer, it is possible to prevent the elastic body from being damaged due to the mounting of the coupler.

According to a sixth aspect of the present invention, there is provided a temperature sensor according to the fifth aspect, wherein the washer is formed of aluminum or a copper alloy, and these materials have high thermal conductivity and deteriorate thermal response of the temperature sensor. Because of the low hardness, processing is easy and high accuracy can be obtained.

The invention according to claim 7 is the temperature sensor according to claim 1, wherein the coupler is formed of a synthetic resin obtained by adding glass to polybutylene terephthalate, wherein glass is added to polybutylene terephthalate as a coupler material. Those having a low specific heat can prevent deterioration of the thermal response in the coupler portion.

In the temperature sensor, a metal body is interposed between the case and the thermistor element, and the thermistor element is brought into contact with the inner peripheral surface of the case via the metal body.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

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

In this temperature sensor, a thermistor element 2 having a negative resistance with respect to temperature is disposed in a case 1 having one end opening made of brass, and an opening located at an upper portion of the case 1 is made of resin. Seal with the molded coupler 3,
The upper end of the opening of the case 1 is caulked to the front surface side of the coupler 3 so that the inside of the case 1 is sealed.

Further, the coupler 3 has two terminals 4 for external connection with gold plating on the surface of a copper alloy, a thermistor element 2, and a lead made of two copper alloys for connecting the thermistor element 2 and the terminal 4. Wire 5 is insert molded. Each of the two lead wires 5 is inserted into a fluorine-based tube 6 to prevent a short circuit therebetween.

In this temperature sensor, FIG.
As shown in FIG. 1, a metal body 7 is interposed between the surface of the thermistor element 2 and the inner peripheral surface of the case 1. According to this configuration, heat transmitted from outside the case 1 is
This is transmitted to the thermistor element 2 via the metal body 7. That is, in the configuration of the conventional temperature sensor, silicon oil having a high specific heat is interposed between the thermistor element 2 and the case 1, and the thermal responsiveness is deteriorated because the specific heat of the silicon oil is high. By changing the silicon oil to the metal body 7, the thermal conductivity between the thermistor element 2 and the case 1 increases, and as a result, the thermal response of the temperature sensor can be improved.

The metal body 7 is disposed so as to cover substantially the entire surface of the thermistor element 2 so that the thermistor element 2
And the heat transfer efficiency can be further increased.

Actually, the metal body 7 has a thickness of 0.1 to 0.2.
The thermistor element 2 is formed by press working so as to have a millimeter bottomed cylindrical shape, and the thermistor element 2 is inserted and fixed into the metal body 7 and inserted into the case 1.

In order to fix the metal body 7 to the thermistor element 2, the thermistor element 2 is pressed into the metal body 7, or after the thermistor element 2 is inserted into the metal body 7, the metal body 7 is punched. The metal member 7 can be fixed by performing deformation processing such as caulking or by integrally forming the metal body 7 at the time of forming the coupler 3 in the same manner as the terminal 4. However, in the deformation processing, the processed periphery bulges up to the case 1. In some cases, the fitting may be displaced due to the molding resin and the insertability into the case 1 may be deteriorated. In this embodiment, the fixing by press-fitting may be difficult. Has adopted.

In view of the fact that the water resistance to the thermistor element 2 is deteriorated by changing the silicon oil to the metal body 7, the elastic body 8 is arranged at the contact portion between the case 1 and the coupler 3. When the opening of the case 1 is swaged to the coupler 3, the elastic body 8 is elastically deformed by the pressing and the abutting portion can be securely sealed. It is possible to ensure the same waterproofness as the one injected with.

Further, it is preferable that the elastic body 8 is made of nitrile rubber or ethylene propylene rubber and has a rectangular or circular cross section.

That is, nitrile rubber and ethylene propylene rubber are excellent in heat resistance and durability as characteristics, and have a remarkable advantage in a use environment of a temperature sensor. In the case of elastic deformation, it spreads uniformly in the contact portion between the case 1 and the coupler 3, and the sealing at the contact portion can be enhanced.

Further, the elastic body 8 may be damaged by burrs or the like generated on the surface of the resin-molded coupler 3 at the time of caulking, but a metal washer 9 is provided between the elastic body 8 and the coupler 3. The damage of the elastic body 8 due to the caulking step can be prevented by interposing the elastic member 8.

The washer 9 is preferably made of aluminum or a copper alloy.

That is, these materials have high thermal conductivity and do not degrade the thermal response of the temperature sensor, and since they are low in hardness, they can be easily processed and high accuracy can be obtained.

FIG. 1 shows the shape of the coupler 3.
In order to fix the thermistor element 2 in the case 1 as shown in FIG.
The resin is integrally molded up to the lower end of the
The influence of the resin forming the coupler 3 on the thermal responsiveness is suppressed by reducing the thickness of the resin molded portion adjacent to the thermistor element 2 as much as possible.

Further, regarding the resin material for forming the coupler 3, a synthetic resin obtained by adding about 30% of glass to polybutylene terephthalate is used. Generally, as a resin material of such a coupler 3, a synthetic resin obtained by adding glass to polybutylene terephthalate, polyamide, or polyphenylene sulfide is used. As described above, in a temperature sensor that requires high thermal responsiveness, it is important to use a synthetic resin obtained by adding glass to polybutylene terephthalate.

When actually comparing the thermal responsiveness of a temperature sensor equipped with a coupler using these three types of synthetic resins,
Those using polybutylene terephthalate have improved thermal responsiveness for about 0.3 seconds compared to those using other polyamides or polyphenylene sulfide.

Although not implemented in this embodiment, by performing fin processing on the outer surface of the case 1 near the thermistor element 2, the surface area in this portion can be increased, and the surface area of this part can be increased. With the increase, the thermal response of the temperature sensor can be improved.

Next, the evaluation results regarding the thermal responsiveness of this temperature sensor will be shown.

The evaluation method is as follows. First, a temperature sensor is attached to an evaluation connector, and the resistance value of the temperature sensor at 72.4 ° C., which is a temperature for evaluating thermal responsiveness, is measured. And stabilize its resistance value. Then, the temperature sensor stabilized at ordinary temperature was moved so as to be completely immersed together with the evaluation connector in a constant temperature bath boiled to 100 ° C., and measured at 72.4 ° C.
Thermal time constant (τ) is the time required to reach the resistance value at
Is what you want.

As a result, τ was about 5 seconds in the conventional temperature sensor in which the case 1 was filled with silicone oil, whereas τ was about 1 in the temperature sensor of the present embodiment.
Seconds, and the result was that the thermal response was improved by about 80%.

[0034]

As described above, according to the present invention, the thermal response of the temperature sensor can be improved by bringing the thermistor element into contact with the case via the metal body.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view of a part around the thermistor element of the temperature sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Case 2 Thermistor element 3 Coupler 4 Terminal 7 Metal body 8 Elastic body 9 Washer

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Keiji Shiraishi 55-12 Osumihama, Kyotanabe-shi, Kyoto Matsushita Nitto Electric Co., Ltd. F term (reference) 2F056 QC04 QC05 QC16

Claims (7)

[Claims] 1. A case made of metal having an open end, a thermistor element disposed in the case, a coupler for closing an opening of the case, and one end connected to the thermistor element and the other end led out. A temperature sensor comprising: a terminal; and the thermistor element abutting on the case via a metal body. 2. The temperature sensor according to claim 1, wherein the metal body is disposed so as to surround substantially the entire surface of the thermistor element. 3. The temperature sensor according to claim 1, wherein the coupler is press-fixed to an opening of the case, and an elastic body is interposed at a contact portion between the coupler and the case. 4. The temperature sensor according to claim 3, wherein the elastic body is formed of nitrile rubber or ethylene propylene rubber. 5. The temperature sensor according to claim 3, wherein a washer made of metal is interposed between the coupler and the elastic body. 6. The temperature sensor according to claim 5, wherein the washer is formed of aluminum or a copper alloy. 7. The temperature sensor according to claim 1, wherein the coupler is formed of a synthetic resin obtained by adding glass to polybutylene terephthalate.