Electricity: magnetically operated switches – magnets – and electr – Electromagnetically actuated switches – Polarity-responsive
Patent
1993-10-29
1995-08-08
Donovan, Lincoln
Electricity: magnetically operated switches, magnets, and electr
Electromagnetically actuated switches
Polarity-responsive
335202, H01H 5122
Patent
active
054402859
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention generally relates to a closed type electromagnetic relay, and more particularly to a closed type electromagnetic relay with the characteristic insulating structure of a coil block.
BACKGROUND OF THE INVENTION
In a conventional electromagnetic relay of a closed type intended to guard against the ambient atmosphere, a coil block, which is an internal component of the electromagnetic relay, has sometimes been coated with an insulating resin through injection molding to enhance the insulating properties between a coil of the coil block and a contacting point.
To seal the electromagnetic relay of the above-described type, the electromagnetic relay is first installed in the vacuum space at high temperatures for vacuum process. After the air inside the electromagnetic relay is discharged and an inert gas fills the electromagnetic relay in the inert gas atmosphere, the electromagnetic relay is sealed.
Meanwhile, an example of a compact-size electromagnetic relay such as proposed in Japanese Patent Laid-Open Publication No. 02-319922 (319922/1990) secures an insulation distance between the coil and contacting point by providing an insulating member between a movable block arranged at the lower side of the coil block and the coil block.
If the insulating resin is coated all over the coil winding section of the coil block through injection molding, it is necessary for a mold to be vented in order to prevent a short shot (insufficient filling) or a burn mark, and moreover, it is quite difficult to set the molding conditions, e.g., injection pressure, temperatures of the mold and the like.
Since the electromagnetic relay is put in the high temperature atmosphere during the vacuumizing process, the coated resin may be broken by the gas generated from the coil or the like, thus making it hard to obtain a desired dielectric strength between the coil and contacting point.
Moreover, an extraordinary force exerted on the coil resulting from the pressure of the resin during injection molding causes the coil to break in some cases.
SUMMARY OF THE INVENTION
The present invention provides a closed type electromagnetic relay which substantially eliminates the above-described inconveniences inherent in the prior art, whereby a coil block is easily coated with an insulating resin without causing coil to break during sealing or the coated resin to break after sealing.
In the conventional electromagnetic relay, the insulating member is processed separately beforehand, so that the number of components of the electromagnetic relay is disadvantageously increased. The positioning accuracy is accordingly required to be tight. Otherwise, the distance between a fixed contacting point of a fixed contact element integrally formed with the insulating member and a movable contacting point of a movable block is prone to vary. What's worse, the insulation distance secured by the insulating member is not enough.
Accordingly, the present invention also provides an electromagnetic relay having superior insulating properties in which the distance between contacting points can be set correctly.
In order to accomplish the above-described advantages of the present invention, a sealed type electromagnetic type is provided which has a contact opening/closing mechanism arranged in the vicinity of a coil block consisting of a coil wound around an iron core. An insulating resin is injection molded to the surface of the coil block so that a part of the side opposite the contact opening/closing mechanism of the coil block is exposed. The force impressed to the coil from the resin pressure during injection molding is eased by the exposed part and moreover the gas generated from the coil or the like after injection molding is discharged through the exposed part.
In another aspect of an electromagnetic relay of the present invention, fixed contact elements are integrally formed by the forming process with a coil block comprising a coil wound around an iron core. The coil block is resin molded at least up to a pa
REFERENCES:
patent: 4517537 (1985-05-01), Weiser et al.
patent: 4912438 (1990-03-01), Yokoo
patent: 5270674 (1993-12-01), Nakanishi et al.
Japanese Utility Model Laid-Open Publication No. 51-162950, published Dec. 25, 1976.
Japanese Utility Model Laid-Open Publication No. 47-29436, published Dec. 4, 1972.
Japanese Patent Laid-Open Publication No. 59-224024, published Dec. 15, 1984.
Nakanishi Yoichi
Noda Masayuki
Sako Kazumi
Sato Ryuichi
Takegahara Ikuo
Donovan Lincoln
Omron Corporation
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