Potted device

Details Potted device Potted device

1999-09-23

2001-06-12

Barrera, Ramon M. (Department: 2832)

Electricity: magnetically operated switches, magnets, and electr

Magnets and electromagnets

Magnet structure or material

C335S278000, C336S096000

Reexamination Certificate

active

06246309

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a potted device, especially a potted, explosionprotected electromagnet comprising a coil, preferably embedded in a potting compound in a housing, and a ferromagnetic circuit, which can be connected to external lines via contact elements arranged inside the housing and likewise embedded in the potting compound.
2. Description of the Related Art
Potted devices have been known for a long time and are described, for example, by DE-G 90 03 343.4.
As it is a requirement for potted, explosion-protected electromagnets that the potting compound must ensure proper electric insulation to prevent any explosive gas mixture from reaching any ignition sources, and that the potting compound be capable of withstanding mechanical strains and of guarding the respective operational equipment from chemical influences, it is necessary to embed the contact elements, required for connecting external lines, in the potting compound as well. In addition it must be provided to arrange the contact elements inside the housing in a space separated from the surroundings, whereby it is additionally guaranteed that no explosive gas mixtures can reach the contact elements.
In the case of certain known devices, as described for example in Applicant's leaflet 7501453.05.04.96, the contact elements are arranged in a cavity of the housing that is accessible from the outside and can be opened, for example, by a plate.
Such an arrangement of the contact elements makes the operation of leading up the external lines and connecting them with the contact element(s) problematic and time-consuming, especially as tools, for example screwdrivers or the like, can be used inside the cavity of the housing only with great difficulty.
BRIEF SUMMARY OF THE INVENTION
Now, it is the object of the present invention to improve a potted device of the kind described in the preamble in such a way as to permit easy production and a simple structure and to ensure that the external lines can be easily led up to, and establish contact with, the contact elements.
This object is achieved with a potted device of the before-mentioned kind by the fact that the contact elements are arranged in a cavity in such a way as to protrude beyond the potting compound that closes the housing off at its end face, the cavity being formed by a cover element that can be mounted on the housing in the area of the contact elements, and that a wiring duct, which is connected with the cavity, is provided in the potting compound.
Making the contact elements protrude beyond the potting compound, that closes the housing off at its end face, and arranging a wiring duct, connected with the cavity, in the potting compound provides the particularly important advantage to facilitate the operation of leading up the external lines to the contact elements and to permit tools, such as screwdrivers or the like, to be optimally used.
Another advantage lies in the fact that the cavity in which the contact elements must be arranged to protect them from exposure to explosive gas mixtures or the like is formed by a preferably domed cover element that covers the housing in the area of the contact elements on its end face and that can be fixed to the housing after contact to the contact elements has been established. In combination with that cover element the protruding contact elements permit easy assembly of the external lines and an explosion-proof arrangement of the contact elements in the cavity formed by the cover element. It is understood that the cover element need not necessarily be domed, but may also exhibit any other shape providing a cavity. A still further advantage lies in the fact that due to the plane supporting surface of the cover a plane sealing element can be used.
As in many cases not only the contact elements but also circuits or other components, including fuses for example, must be embedded in the potting compound together with the contact elements, the coil and the ferromagnetic circuit, and as the thermoplastic compound is injected around those electric components at high pressure so that damage to the components cannot be excluded, it is provided in a very favorable embodiment that the contact elements and other electric components are arranged in a pot-shaped component that can be fixed in the housing, and are embedded in a thermoset molding compound. This ensures that especially the very delicate fuses will not be damaged.
The coil, the ferromagnetic circuit and the before-mentioned pot-shaped component, filled with the thermoset molding compound, are enclosed by a thermoplastic molding compound applied by injection molding.


REFERENCES:
patent: 3657677 (1972-04-01), Hunt et al.
patent: 4412196 (1983-10-01), Teichert
patent: 5359982 (1994-11-01), Taruya
patent: 5466887 (1995-11-01), Hasegawa
patent: 05 14 65 514 (1969-12-01), None
patent: 90 03 343 (1990-07-01), None
patent: 42 358 22 (1993-04-01), None
patent: 0 187 902 (1986-07-01), None
patent: 0662 696 (1995-07-01), None
Leaflet No. 7501453-05.04.96 by Herion-Werke KG (German Version). No Date.
Leaflet No. 7501453-4/99 by IMI Norgren-Herion Fluidtronic GmbH & Co. KG (German and English Version). No Date.

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