JPH0350628Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to the structure of a coaxial plug that is highly heat-resistant and liquid-tight, and particularly relates to a coaxial plug for electrically connecting a heat-sensitive element used inside a microwave oven to a microwave oven. Regarding the structure of the plug. [Prior Art] One method for controlling the temperature of a microwave oven is to detect the temperature of an object to be heated (food) and control high-frequency oscillation based on the temperature change. According to this method, a temperature probe is provided inside the microwave oven, and the temperature is detected by contacting or inserting the temperature probe into the object to be heated. A temperature probe consists of a heat sensitive element such as a thermistor, a shielded cord extending from the heat sensitive element, and a coaxial plug coupled to the tip of the shielded cord. By connecting this coaxial plug to the jack of a microwave oven, changes in the electrical variables of the heat-sensitive element are detected by a temperature detection control device. This detection signal is then applied to the magnetron power supply control device to control the microwave. The temperature probe and jack are located within the heating chamber of the microwave oven. For this reason, in recent microwave ovens that also use infrared heaters, where the temperature inside the heating chamber becomes extremely high, a high degree of heat resistance is now required of the temperature probe. To meet this requirement, coaxial plugs for temperature probes use materials with excellent heat resistance, such as polyphenylsulfone resin, as an insulator between the outer electrode and the center electrode. [Problems to be solved by the invention] Thermal problems were solved by using a resin with excellent heat resistance. However, because the expansion rate of resin at high temperatures is greater than that of metal electrodes, and because the resin thins due to exposure to high temperatures, a very small gap may be created between the contact surface between the external electrode of the coaxial plug and the resin. There is. Therefore, a degree of freedom in rotation is created between the external electrode and the resin. In this case, abnormal stress is applied to the connection between the coaxial plug and the shielded cord, which has the drawback of causing a short circuit or disconnection accident. Furthermore, water vapor generated from the heated object during cooking will enter the coaxial plug through this gap, condensing at the connection between the center electrode and the shield cord, forming water droplets, and causing a short circuit. . An object of the present invention is to provide a liquid-tight coaxial plug that can eliminate these drawbacks. [Means for Solving the Problems] A liquid-tight coaxial plug according to the present invention includes a cylindrical external electrode, a center electrode disposed inside the external electrode, and a space filled between the external electrode and the center electrode. The coaxial plug has a coaxial plug having an insulator, characterized in that silicone rubber is used as the insulator. Silicone rubber is a rubber-like elastic material whose main component is organic polysiloxane with a three-dimensional network, and additives such as inorganic fillers and heat-resistant stabilizers are added as necessary. The chemical structure of the organic polysiloxane and the types of inorganic fillers, heat stabilizers, etc. are appropriately selected depending on the application. Such silicone rubber can be easily obtained by curing uncured silicone rubber (many commercially available) before forming a three-dimensional network through a chemical reaction. Silicone rubber has both heat resistance and rubber-like elasticity, and does not cause thinning even when exposed to high temperatures, and no gaps are created between the outer electrode and the center electrode and the silicone rubber. Condensation reactions, radical reactions, and addition reactions are common and well known as curing reactions for silicone rubber. The condensation reaction is In the formula, R represents a hydrocarbon group, and the other three bonds of the silicon atom do not participate in the reaction. radical reaction is It is expressed as The addition reaction is It is expressed as Among these three types of chemical reactions, in the case of the addition reaction of formula (4), there are no reaction by-products. Therefore, silicone rubber cured by addition reaction does not have any adverse effects such as foaming or decomposition due to by-products when exposed to high temperatures. Therefore, in the present invention, if the uncured silicone rubber injected between the outer electrode and the center electrode is of the type that hardens by an addition reaction, there will be no by-products, and it will have better heat resistance. preferable. [Example] Next, an example of the present invention will be described with reference to the drawings. FIG. 1 is a vertical cross-sectional view of a main part of an embodiment of the present invention. This coaxial plug includes a cylindrical outer electrode 10 made of a metal material, a center electrode 20 made of a metal material disposed coaxially inside the outer electrode 10, and a space between the outer electrode 10 and the center electrode 20. It consists of an insulator 30. The center electrode 20 includes a chip 21 located at the tip of the coaxial plug, and a chip 21 located at the tip of the coaxial plug.
It consists of a tip pin 22 extending in the axial direction from the tip.
The other end 23 of the tip pin 22 protrudes from the insulator 30 and is connected to the core wire of a shielded cord (not shown) by soldering. The insulator 30 is made of silicone rubber that is cured by an addition reaction. This silicone rubber can be used as a repeating unit.

【formula】

【formula】

An uncured liquid silicone having the formula is cured using a platinum-based catalyst. The coaxial plug of this embodiment has the following advantages. a) Since silicone rubber is used as the insulator, there is no thinning phenomenon even when exposed to high temperatures, and there is no gap between the electrode and the electrode. As a result, moisture does not enter through the gap, and insulation resistance does not decrease. b. Since silicone rubber that is cured through an addition reaction is used, there are no alcohol by-products or radical decomposition products compared to those using a condensation reaction or a radical reaction. These by-products are often acidic substances or compounds easily derived into acidic substances. It is known that acidic substances lower the molecular weight of silicone rubber and thereby lower mechanical properties, but addition-type silicone rubber does not have this effect. c The coaxial plug of this example can be used as part of a microwave temperature probe as described above, but the silicone rubber is recognized as safe under the Japanese Food Sanitation Act and the US Food Act (FDA). There are many cases. FIG. 2 is a longitudinal sectional view of a second embodiment of the present invention. This coaxial plug also mainly includes a cylindrical external electrode 110 formed of a metal material, and this external electrode 1.
It consists of a center electrode 120 made of a metal material coaxially arranged inside the electrode 10 and an insulator 130 filled between the outer electrode 110 and the center electrode 120. The center electrode 120 consists of a tip 21 located at the tip of the coaxial plug and a tip pin 122 extending from the tip 121 in the axial direction. The external electrode 110 has an injection hole 111 for injecting the insulator 130.
is formed. Chip 121 and external electrode 11
0, an insulating collar 140 made of polyphenylsulfone resin is fitted. Insulation collar 14
An air vent hole 141 is formed on the chip 121 side of 0. The shielded cord 150 includes, in order from the inside, a core wire 151, an endothelial insulator 152, a yield wire 153,
It is composed of a sheath 154. These are sequentially cut out, and the shield wire 153 is electrically connected to the external electrode 110 via the metal sleeve 160. Small diameter portion 161 of metal sleeve 160
is fixed to the shield wire 153 by caulking, and the large diameter portion 162, together with the external electrode 111, is fixed to the sheath 154 by caulking. The core wire 151 of the shielded cord 150 is connected to the connecting fitting 1
70 to the tip pin 122. A body 180 serving as a knob is integrally formed with an insulator 130 on the shielded cord 150 side of the coaxial plug. The insulator 130 is made of silicone rubber, which is the same material as the insulator 30 in FIG. This silicone rubber is in a liquid state before hardening, and the external electrode 110
It is press-fitted from the injection hole 111. At this time, air inside the external electrode 110 can escape through the air vent hole 141. At the same time as this silicone filling, the body 180 is also molded integrally with the insulator 130. The coaxial plug of the second embodiment has the following advantages in addition to the advantages a to c described in the first embodiment. d Since the silicone rubber covers the connecting portion between the tip pin and the core wire, the insulation performance is superior to that of the first embodiment. e Silicone rubber is more prone to bending and stretching than conventional resin insulators, but since the resin insulating collar is fitted between the chip and the external electrode, the chip becomes mechanically unstable. is prevented. f Since air vent holes are formed in the insulating collar, no air bubbles are generated in the silicone rubber when the silicone rubber is press-fitted, and the problem of insulation deterioration due to air bubbles is solved. <Example> As a comparative example, a coaxial plug shown in FIG. 1 in which the insulator 30 was made of polyphenylsulfone resin was prepared. As examples of the present invention, coaxial plugs of the first embodiment and the second embodiment were prepared. Coaxial plugs are used inside microwave ovens in the following ways: After being kept at the maximum temperature of a microwave oven, approximately 250°C, for a specified period of time, it is washed with hot or cold water. Therefore, the following test method was adopted. First, the coaxial plug was left in a constant temperature bath at 250°C for a certain period of time, and then boiled for 30 minutes. After such treatment, the insulation resistance between the electrodes was measured. The insulation resistance before the test was essentially infinite, but after the test it became as shown in Table 1.

[Table] As shown above, the coaxial plug of the present invention showed excellent insulation resistance even after being held at a high temperature and then boiled. This indicates that the silicone rubber had excellent sealing properties and no moisture entered the coaxial plug. [Effects of the invention] As explained above, the liquid-tight coaxial plug of the invention uses silicone rubber as the insulator, and due to the rubber-like elasticity and heat resistance of silicone rubber, it can be insulated even under adverse conditions of high temperature and high humidity. There is no gap between the object and each electrode, and excellent sealing performance is maintained.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of the main part of the first embodiment of the present invention,
FIG. 2 is a longitudinal sectional view of a second embodiment of the present invention. 10,110...External electrode, 20,120...Center electrode, 30,130...Insulator.

Claims (1)

[Claims for Utility Model Registration] (1) A coaxial plug having a cylindrical external electrode, a center electrode disposed inside the external electrode, and an insulator filled between the external electrode and the center electrode. A liquid-tight coaxial plug characterized in that silicone rubber is used as the insulator. (2) The liquid-tight coaxial plug according to claim 1, wherein the silicone rubber is cured by an addition reaction. (3) The center electrode consists of a tip located at the tip of the coaxial plug and a tip pin extending in the axial direction from the tip, and the tip pin is connected to the core wire of the shielded cord inside the outer electrode, and The liquid-tight coaxial plug according to claim 1, characterized in that the material covers at least the tip pin and the connecting portion between the tip pin and the core wire. (4) an insulating collar made of synthetic resin is fitted between the chip and the external electrode, and the external electrode has at least one injection hole for injecting the insulator into the external electrode; The liquid-tight coaxial plug according to claim 3, wherein the insulating collar is formed with at least one air vent hole. (5) The liquid-tight coaxial plug according to claim 4, wherein the silicone rubber is cured by an addition reaction.