JPS59202038A - Manufacture of temperature sensor - Google Patents

Abstract

PURPOSE:To obtain a temperature sensor with complete characteristics with an accurate positioning made possible by a method wherein leads are connected axially at both ends of a thermistor, after one lead is bent in U-shape to parallel the other, a resin is fastened on both the leads and the assembly is inserted into a case. CONSTITUTION:One of leads 1 and 2 connected to both ends of a thermistor 3, for example, the lead 1 is bent in U-shape and a resin 5 is fastened the leads 1 and 2 by injection molding. The resin 5 is so roughly equal to the inner diameter of a large inner diameter section 41 of a case 4 to be insertable thereinto. Then, the tip 43 of the case 4 is filled with an insulation oil, silicone rubber or the like and after the thermistor 3 is inserted thereinto, the rear end of the resin 5 is fixed with a resin 6 or the like. In this manner, a temperature sensor excellent in the durability suitable for automobiles can be formed with a high yield as such with complete characteristics without positional deviation in the thermistor, dispensing with a defoaming process or the like for bubbles as generated when the resin 5 is injected and hardened afterwards.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a temperature sensor suitable for use in, for example, a water temperature gauge, an oil temperature gauge, or an air temperature needle for automobiles.

BACKGROUND OF THE INVENTION FIGS. 1A to 1C are diagrams showing a conventional manufacturing method of this type of temperature sensor. First, as shown in FIG. 1(a), one of the lead wires 1 and 2 of the glass-sealed thermistor 3 has lead wires 1 and 2 led out in the axial direction at both ends.
For example, after bending the lead wire 1 and forming it into an appropriate shape such as a U-shape, as shown in FIG. Insert the thermistor 3 side toward the tip side. Next, as shown in FIG. 1C, insulating resin 5 is injected and filled around the thermistor 3 and lead wires 1 and 2 inserted into the inner diameter portion 41 of the case 4 and hardened. The insulating resin 5 is
It serves as a support member that supports the thermistor 3 and its lead wires 1.2 within the case 4. The outer peripheral surface of the case 4 has a stepped shape in which the diameter becomes smaller toward the tip, and a threaded portion 42 for mounting is provided on the outer periphery of the intermediate step, and the thermistor 3 is positioned at the tip 43. ing. In addition, the inner diameter portion 41
The tip portion where the thermistor 3 is located is formed to have a small diameter in order to improve the heat conduction characteristics from the case 4 to the thermistor 3. Reference numeral 44 represents a flange portion for determining the mounting position.

Disadvantages of the Prior Art However, the conventional manufacturing method described above has the following drawbacks.

(a) After inserting the thermistor 3 and the lead wire 1.2 into the inner diameter part 41 of the case 4, the thermistor 3 and its lead wire 1.2 can be fixed in a predetermined position until the insulating resin 5 is injected and filled. Difficult, thermistor 3 and lead wire 1.
2 is very likely to cause misalignment. Therefore, due to the misalignment of the thermistor 3 with respect to the inner wall surface of the case 4, the heat conduction characteristics from the case 4 to the thermistor 3 and the resulting temperature detection characteristics vary in each temperature detection sensor, making it difficult to use sensors with uniform characteristics. It was difficult to manufacture with good yield.

(b) The inner diameter part 41 of the case 4 is a bag-like space without an outlet, and there is no air vent hole when injecting and filling the insulating resin 5.
There was also the problem that bubbles were generated inside the insulating resin 5, and the heat conduction characteristics of the insulating resin 5 were changed due to the bubbles.

(c) This problem caused by foam can be solved by adding a defoaming step, but this has the disadvantage of increasing the number of steps.

(d) From the perspective of the temperature detection operation by the thermistor 3, it has a structure that allows it to come into direct contact with the temperature to be measured, such as water, oil, or air.
It is best to leave the space where the temperature to be measured flows through without filling it. However, in the conventional device, since the entire inner diameter portion 41 of the case 4 is filled with the insulating resin 5, it is impossible to adopt such a structure, and there is a limit to the improvement in detection sensitivity.

(E) When trying to obtain a small temperature sensor, the case 4 and its inner diameter portion 41 are naturally reduced in size, making it difficult to inject and fill the insulating resin 5.

Purpose of the Invention The present invention solves two conventional technical problems, and makes it possible to reliably insert and position a thermistor at a predetermined position in a case without causing any positional scratches, and to use an insulating resin. The purpose of the present invention is to provide a manufacturing method that can efficiently manufacture temperature sensors with uniform characteristics at a high yield, even if they are small, with no room for bubbles to form inside, and without the need for a defoaming process. shall be.

Structure of the Invention In order to achieve the above object, the manufacturing method of the invention is characterized in that after resin is fixed to at least the lead wire of the thermistor, the thermistor is inserted into the inner diameter of the case.

Embodiment FIGS. 2(a) to 2(d) are diagrams showing steps of a method for manufacturing a temperature sensor according to the present invention. First, as shown in FIG. 2(a), a glass-sealed thermistor 3 with lead wires 1 and 2 led out in the axial direction at both ends is placed so that the lead wires 1 and 2 are parallel to each other with an appropriate distance between them. After forming into a U-shape, an insulating resin 5 is fixed to the intermediate portion of the lead wires 1 and 2, as shown in FIG. 2(b). This insulating resin 5 is fixedly formed by means such as injection molding.

Suitable examples of the insulating resin 5 include epoxy resin, nylon, polyethylene resin, silicone resin, glass epoxy resin, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), or polycarbonate. As a result, as shown in FIG. 2(C), a thermistor is obtained in which an insulating resin 5 having a circular shape or the like that fits the inner diameter of the case described later is fixed to the intermediate portion of the lead wires 1 and 2.

- As described in , the present invention has a structure in which the insulating resin 5 is fixed in advance to the leads lit and 2 of the formed thermistor 3. It is possible to securely fix the material while maintaining the positional relationship at a predetermined constant value.

Next, as shown in FIG. 2(d), the thermistor 3 is inserted into the inner diameter portion 41 of the case 4 made of a metal material with good thermal conductivity, with the thermistor 3 facing toward the tip.

The inner diameter portion 41 of the case 4 has a structure in which an inner diameter portion 411 having an inner diameter approximately equal to the outer diameter of the insulating resin 5 and an inner diameter portion 412 having a smaller diameter than the inner diameter portion 4↓1 are connected in a stepped manner. When the insulating resin 5 is press-fitted into the inner diameter portion 411, the thermistor 3 is assembled so as to be located at the inner diameter portion 412. In this press-fitting assembly process, the tip end surface 51 of the insulating resin 5 comes into contact with the stepped surface 413 formed between the inner diameter portions 411 and 412, and the inner diameter portion 412
The thermistor 3 is positioned at. The rear end of the insulating resin 5 is fixed with a resin 6.

Further, the inner diameter portion 412 in which the thermistor 3 is accommodated may be filled with a filler 7 having good thermal conductivity, such as oil, silicone rubber, resin, compound, or the like.

As described above, in the present invention, the lead wire 1.
2 and thermistor 3 to a predetermined constant value, the insulating resin 5 is fixed and inserted into the case 4, and the assembling process is performed while positioning. There is no room for misalignment during the process, the relative positional relationship of the thermistor 3 to the inner surface of the inner diameter portion 41 of the case 4 is kept constant, and stable temperature detection characteristics without variations can be obtained even for individual temperature sensors. , yield is improved.

Further, since the step of injecting and filling the inner diameter portion 41 of the case 4 with insulating resin is not necessary, there is no generation of bubbles and fluctuations in temperature detection characteristics due to the generation of bubbles, and a defoaming step is also not necessary.

Furthermore, there is no insulating resin injection filling process, and the thermistor 3 is pre-filled.
It is only necessary to insert the lead wire 1.2 with the insulating resin 5 fixed into the inner diameter part 41 of the case 4. For example, as shown in FIG. It is also possible to improve the heat detection sensitivity by providing a structure in which the thermistor 3 is brought into direct contact with the temperature-tested atmosphere.

FIGS. 4(a) and 4(b) are diagrams showing manufacturing steps in another embodiment of the present invention. The feature of this embodiment is that after forming the lead wires 1 and 2, an insulating resin 5 is fixed to the body including not only the lead wires 1 and 2 but also the thermistor 3, and this is placed inside the inner diameter part 41 of the case 4. It was press-fitted.

In the above embodiment, the insulating resin 5 is formed into a substantially circular shape, but the outer shape of the insulating resin 5 is
In addition to the shape of 1, various shapes can be taken. For example, as shown in FIG. 5, the outer circumferential surface of the insulating resin 5 and the inner circumferential surface of the inner diameter portion 411 into which the insulating resin 5 is inserted may be tapered to simplify the insertion of the insulating resin 5. In this case, instead of fixing the rear end of the insulating resin 5 with the resin 6, it is also possible to adopt a structure in which it is pressed with a spring or the like. Furthermore, as shown in FIG.
It is also possible to adopt a structure that improves the bonding strength between the two.

Effects of the Present Invention As described above, the method for manufacturing a temperature sensor according to the present invention is characterized by fixing resin to at least the Riet wire of the thermistor, and then inserting the thermistor into the inner diameter of the case. It is possible to securely insert and position the patented thermistor in the specified position within the case without causing positional deviation, and there is no room for bubbles to occur in the insulating resin, eliminating the need for a degassing process, etc., and making it compact. It is possible to provide a manufacturing method that can efficiently manufacture temperature sensors with uniform characteristics at a high yield.

[Brief explanation of the drawing]

FIGS. 1(a) to (C) are diagrams showing the manufacturing process of a conventional temperature sensor, FIGS. 2(a) to (d) are diagrams schematically showing the steps of the manufacturing method according to the present invention, and FIG. The figure is a sectional view at the final step in another embodiment, FIGS. 4(a) and 4(b) are diagrams schematically showing the steps in another embodiment, and FIG.
The figure is a sectional view at the final step in yet another embodiment, No. 6
The figure is a sectional view of essential parts in yet another embodiment. l, 2...Lead wire 3@Φ・Thermistor 4...
Inner cavity 5... Insulating resin Fig. 1 43 4z Fig. 4

Claims (6)

[Claims] (1) A method for manufacturing a temperature sensor, which comprises fixing resin to at least the lead wire of the thermistor, and then inserting the thermistor into the inner diameter of the case. (2) The lead wires are composed of a pair connected to both ends of the thermistor in the axial direction, one of which is bent into a U shape and led out in parallel in the same direction, and the resin is fixed to the middle part thereof. A method of manufacturing a temperature sensor according to claim 1, characterized in that: (3) The method of manufacturing a temperature sensor according to claim 1 or 2, wherein a portion of the case in which the thermistor is located has a through hole communicating with the outside. (4) The lead wire is composed of a pair connected to both ends of the thermistor in the axial direction, one of which is bent into a U shape and led out in parallel in the same direction, and the lead wire including the thermistor is 2. The method of manufacturing a temperature sensor according to claim 1, wherein the resin is fixed to the substrate. (5) The outer circumferential surface of the resin and the inner circumferential surface of the case that abuts the outer circumferential surface of the resin have a taper. 4
2. Method for manufacturing the temperature sensor described in section. (6) A portion of the lead wire to which the resin is fixed,
The method for manufacturing a temperature sensor according to claim 1, 2, 3, 4, or 5, characterized in that the temperature sensor is bent in a zigzag manner.