JPS61142430A - Temperature detector - Google Patents

Abstract

PURPOSE:To prevent infiltration of moisture from outside, by working the outside of the opening of an inner case housed in a metal case for electric insulation in a concave ring to seal. CONSTITUTION:A concave-ring-shaped flange is formed outside the opening of an inner case 14. The filling and molding of a molding resin 16 into a metal case 11 are performed as being heated. The metal case 11 and a terminal 17 are molded in one-piece being held on a resin mold securely so that the inside of the inner case and the part of the opening formed in a concave ring will be filled sufficiently. Thus, as the part of the opening thus formed in a concave ring is filled sufficiently with the molding resin, a sealing can be made to keep moisture from infiltrating inside in the combination of material having any coefficient of thermal expansion thereby preventing deterioration in the electric insulation resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a temperature detector for detecting the temperature of liquids such as water and oil.

BACKGROUND OF THE INVENTION Conventionally, this type of temperature detector has had a structure as shown in FIG. In FIG. 2, an inner case 4 is inserted into a metal case 1, a ceramic element 2 and a terminal 7 are connected via a lead wire 3 with solders 5 and 8, and a molded resin 6 is inserted from above. It was filled and molded in one piece.

Problems to be Solved by the Invention However, with such a structure, if the metal case 1, inner case 4, and molded resin 6 are made of different materials, each has a different coefficient of thermal expansion. A gap may be formed at the interface of the molded resin 6 or the interface between the inner case 4 and the molded resin 6, or peeling may occur due to changes in the thermal environment during use. Therefore, if a conventional structure is used in a humid place or exposed outdoors, moisture will infiltrate through the above-mentioned gap as the environmental temperature changes, and the moisture will reach the lead wire 3 or the ceramic element 2. Then, metal case 1 and terminal 70
There was a problem in that the electrical insulation resistance between the two was significantly deteriorated.

Therefore, the present invention aims to solve these problems.
This prevents insulation from deteriorating even when used under adverse thermal conditions.

Means for Solving the Problem In order to solve this problem, the present invention has a method in which the outside of the opening of the inner case, which is the joint between the inner case and the filled resin (molded resin), is shaped into a concave annular shape. be.

With this configuration, even if the inner case and the molded resin are made of different materials and have different coefficients of thermal expansion, the inner case can be sealed with the inner or outer surface of the concave annular part provided on the outside of the concave annular opening. It is resistant to changes in the thermal environment during use and does not cause deterioration of electrical insulation.

In other words, when comparing the materials of the inner case and molded resin, if the molded resin material has a larger coefficient of thermal expansion than the material of the inner case, it will be filled and molded at high temperature, then cooled and expanded in the core direction on the outer surface of the inner case. Due to heat shrinkage, stress is constantly applied and the seal can be removed. On the other hand, if the molded resin material has a smaller coefficient of thermal expansion, it is filled and molded at a high temperature and then cooled to form a seal on the inner surface of the inner case, which is processed into a concave annular shape.

As a result of the above, even if there is a change in ambient temperature below the heat distortion temperature of the resin used, there will be no gap between the inner case and the molded resin, so there will be no infiltration of moisture and no deterioration of electrical insulation resistance. It becomes.

Embodiment Hereinafter, one embodiment of the present invention will be described based on all the attached drawings.

In Figure 1, 11 has mounting screws on the outside,
In consideration of thermal responsiveness, the tip part which is the heat sensitive part is a thin metal case, and an inner case 14 with a bottom made of an insulating material such as resin is inserted into the metal case. The opening has a concave annular collar on the outside. Moreover, the inner case 14 is inserted so that the heat-sensitive part (tip part) is in contact with the inner surface of the case 11, but the opening on the opposite side is inserted while maintaining a sufficient distance from the inner surface of the case. From above, the ceramic element 18
Terminals 17i and 17i for external extraction are relay-connected with solder 18 and solder 15 through the wire 13, respectively, and are inserted from the ceramic element 12 side and set in a resin molding mold, and the molded resin 16 is placed in the metal case. It is filled and molded while being injected. Filling and molding is performed in a heated state, and while the metal case 11 and terminal 17 are securely held in the resin molding mold, the inside of the inner case and the concave ring-shaped part of the opening are sufficiently filled. It is integrally molded.

As described above, even if the thermal expansion cases of the inner case material and the molded resin material are different, the concave annular part of the inner case is fully filled with molded resin into the part where the opening is processed into a concave annular shape. As a result, a seal is maintained on the inner circumferential surface, preventing moisture from penetrating inside.

In other words, if you choose a material whose coefficient of thermal expansion is larger for the molding resin than for the inner case material, the two materials will simultaneously shrink in the core direction after being filled and molded at a high temperature, but the molding resin will shrink at the same time. Since the degree of shrinkage is greater in the inner case, shrinkage stress is constantly applied to the outer circumferential surface of the inner case, creating a seal in this area. Also, the coefficient of thermal expansion is opposite, and molded resin material has /
In the case of JS, heat shrinkage stress is constantly applied to the inner circumferential surface of the concave annular part of the inner case, and a seal is created at this part.

Therefore, with this structure, the seal can be removed with any combination of materials having any coefficient of thermal expansion, preventing moisture from entering the interior and causing no deterioration of electrical insulation resistance.

Effects of the Invention The present invention prevents moisture from entering from the outside by forming a concave ring on the outside of the opening of an inner case for electrical insulation used when housed in a metal case to create a seal. I can do it. In particular, the seal can be maintained even if the material undergoes thermal expansion or contraction due to changes in ambient temperature, making it thermally and mechanically strong. Furthermore, the operating temperature range is widened, and use in liquid is also possible.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a temperature sensor according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of a conventional temperature sensor. 1.11...Metal case, 2,12...
・Ceramic element, 3, 13...Lead wire, 4
, 14...Inner case, 5.15...
... Solder, 6.16 ... Molding resin, 7,17
...Terminal, 8,18...Solder. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure fl... Metal case Figure 2 1i

Claims (1)

[Claims] A resin inner case is provided inside the metal case, and a ceramic semiconductor element such as a thermistor is housed inside, and molded resin is filled with the terminal pulled out to the outside.This is an integrally molded temperature sensor. A temperature sensor characterized by having a concave annular shape on the outside of the opening of the inner case, which is the joining part of the inner case.