JPS641728Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a sealed relay with a plastic case, and its purpose is to eliminate nitrogen oxides and NOx by the arc generated from the switching contacts.
is generated, and the NOx and moisture react to form nitric acid.
The purpose of the present invention is to provide a sealed relay that prevents HNO ₃ from corroding the metal parts that make up the opening/closing contacts and the drive device.

Conventionally, in sealed relays with plastic cases, the plastic itself has moisture permeability, so moisture gradually enters through the case during use, and when arcing occurs at the switching contacts, the arc causes nitrogen oxide NOx and moisture. reacts to produce nitric acid, HNO ₃ , which corrodes metal parts. For this reason, some relays have metal plating applied to the outer surface of the plastic case to prevent moisture from entering inside the relay, but it is impossible to remove the moisture that gets inside during the manufacturing process, and even if it were removed, the metal plating would peel off. Or, if the plating film becomes thin over the entire surface after long-term use, the corrosion will begin.

In addition, the moisture permeability of plastic materials is
The following is stated on page 100 of PLASTICS DATABOOK (edited by the Plastics Technical Data Editorial Committee and published by Kogyo Kenkyukai Co., Ltd. on September 15, 1962). (Unit: [g・mil/m ²・day]) Pinylidene chloride (39℃) 1.5-7 Polycarbonate (20℃) 31 Vinyl chloride (38℃) 32 Polystyrene (39℃) 133 Polypropylene (38℃) 8.7 Vinylidene chloride, polycarbonate, and the like are often used as plastic cases for relays, but metal materials are considered to have zero moisture permeability unless they have pinholes.

The present invention was made in view of these matters, and one embodiment of the present invention is shown below in Figures 1 to 4.
This will be explained based on the diagram.

A plastic case 1 is made of a transparent or opaque material, and a nitrogen oxide NOx adsorption metal layer 2 such as copper or nickel is provided on the entire inner surface by plating or sputtering. 3 is a base on which a switching contact (not shown) and a driving device are attached;
Opening/closing contacts and lead pins 4, 5, and 6 electrically conductively connected to the drive device are provided on the base 3 and protrude outward.

The base 3 is attached by closing the opening of the case 1, so that the opening/closing contacts and the driving device are housed inside the case 1. 7 is a sealing layer made of material such as epoxy resin, and base 3
The base 3, the lead pins 4, 5, 6, and the edge of the case 1 are sealed together.

Regarding the chemical resistance of plastics and metals at room temperature, please refer to the above-mentioned PLASTICS
It is listed on page 80 of DATABOOK, and the following is an excerpt for 10% nitric acid. (Evaluation scale: E=Excellent, G=Good, F=Good, P=Poor) Vinyl chloride resin; E Copper; P Polycarbonate; E Brass; P Polypropylene; E Here, the evaluation of E indicates reaction to nitric acid. Things that are difficult to do,
The P rating indicates that the material is likely to react with nitric acid.

The plastic case 1 is made of a plastic case 1 and a transparent material, as shown in FIGS. The switching contacts or the drive device can be made visible from the outside.

In such a sealed relay, moisture that attempts to enter through the plastic case 1 is blocked by the adsorbent metal layer 2 of the case 1.

In addition, moisture that slightly infiltrates into the interior through the notched windows 2a, 2a or exists inside during the manufacturing process will evaporate due to the rise in internal temperature, and the inner surface of the case 1, which is at a low temperature in contact with the outside air (more specifically, the moisture metal layer 2
surface).

and nitrogen oxide NOx due to arcing of switching contacts.
When this occurs, the nitrogen oxide NOx also adheres to the inner surface of the case 1 and reacts with the moisture already attached to form nitric acid _HNO3 . Then this nitric acid _HNO3
reacts with the adsorbed metal layer 2 on the inner surface of the case 1 made of a material that easily reacts with this, becoming stable as, for example, copper nitrate or nickel nitrate, and does not float inside the case 1 as nitric acid gas. In other words, if there is no adsorbed metal layer 2,
When the temperature of the relay drops, nitric acid gas floats inside the case 1 and adheres to metal parts such as switching contacts and drive devices, gradually corroding them.

As described above, according to the present invention, the opening/closing contact and its driving device are sealed in the plastic case 1, and a nitrogen oxide adsorption metal layer such as copper or nickel is provided over almost the entire inner surface of the plastic case 1. In some cases, the adsorbent metal layer adsorbs nitrogen oxides generated from switching contacts and moisture that enters the plastic case during the manufacturing process, and as a result, the nitrogen oxides and moisture react on the adsorbent metal layer. Nitric acid is produced, and this nitric acid reacts with the adsorbed metal layer to produce silver nitrate, nickel nitrate, etc., thereby preventing nitric acid gas from floating, thereby preventing corrosion of the switching contacts, their driving devices, and the constituent metal parts. It can be prevented.

In addition, since the adsorbent metal layer is provided on almost the entire inner surface of the plastic case, even if it is used in a humid place, it will largely prevent moisture from penetrating into the inside of the case. The amount of moisture that reacts with nitrogen oxide is extremely small, making it possible to more reliably prevent corrosion of the opening/closing contacts, their driving devices, and their constituent metal parts.

For these reasons, it is advantageous over conventional products with metal plating on the outer surface in that there is no need to take into account the influence of moisture during the manufacturing process, and the adsorbed metal layer is less likely to be damaged.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of one embodiment of the present invention, Fig. 2 is a sectional front view thereof, Fig. 3 is a perspective view of another embodiment of the invention, and Fig. 4 is a sectional front view thereof. It is. 1...Plastic case, 2...Adsorption metal layer.

Claims (1)

[Scope of utility model registration request] A sealed relay characterized in that a switching contact and its driving device are sealed in a plastic case, and a nitrogen oxide adsorbing metal layer such as copper or nickel is provided over substantially the entire inner surface of the plastic case.