Housing for an electromechanical component

A component housing for an electromechanical component as an aeration opening provided with an insulating shaft formed by an insulating wall extending from the housing wall. The insulating shaft is open to the interior of the housing at an end lying opposite the aeration opening to form an insulating path between voltage carrying parts within the housing and neighboring metallic parts outside of the housing after the aeration opening is opened.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention is directed generally to a housing for an 
electromechanical component having a tightly closed hollow interior and an 
outwardly open or openable aeration opening, and in particular to a 
plastic housing for an electromagnetic relay or similar switching 
equipment. 
2. Description of the Related Art 
Relays which have plastic housings are usually sealed with an adhesive, a 
casting resin, or the like so that the sensitive parts within the housing, 
and in particular the contacts, are protected against the harmful 
influences of washing solutions, soldering agents and the like. 
Under certain circumstances, however, the tightly closed housing can be 
disadvantageous for the further useful life of the relay or similar 
component since the plastic housing, the coil and other parts in the relay 
emit various vapors, gases and the like over the course of time that are 
harmful to the contacts and that generate a microclimate within the closed 
housing. Such emissions may be more harmful to the contacts than normal 
ambient air. It is therefore often standard practice to provide an 
aeration opening in the housing that can be opened only after the 
integration of a relay into the housing. Thus, for example, it is known to 
puncture a prepared, thin walled section of a relay wall, as disclosed in 
German Published Application 30 39 702, or to cut off a cylindrical or 
rectangular bleb at a housing corner as disclosed in German Patent 
Document 87 03 079. However, the possibility of initially covering a 
passage formed in the housing with a foil and then of pulling the foil off 
after the relay has been washed and soldered is also possible. 
There is the risk with such aeration openings that metal parts arranged 
inside the housing in the area of the aeration opening do not have 
adequately long insulating paths from other voltage carrying parts outside 
of the housing. This can occur, for example, when a relay is integrated on 
a first printed circuit board and an aeration opening on an upper side of 
the relay lies in the immediate proximity of an interconnect or a voltage 
carrying terminal member of a second adjacent printed circuit board. 
Difficulties particularly derive when mains relays are involved wherein 
long creep and air paths, for example of at least 8 mm, are required and 
prescribed for protection against electrical shocks. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a housing for an 
electromechanical component which has an aeration opening such that, even 
with integration in the proximity of metallic external parts, the required 
insulating distances are provided from the outside of the housing to 
metallic or voltage carrying parts within the interior of the housing and 
can thus always be guaranteed. 
This and other objects and advantages of the invention are achieved in that 
the aeration opening into the interior of the housing discharges into an 
insulating shaft that is separated from metallic parts within the interior 
of the housing by an insulating wall proceeding from the housing wall and 
that is open toward the interior of the housing at least at an end lying 
opposite the aeration opening. 
The required insulating paths are thus guaranteed by the insulating 
shielding of the aeration opening in the interior of the housing of the 
invention regardless of where the component is integrated and regardless 
of the proximity of metallic or voltage carrying parts. When the aeration 
opening is provided in a corner region of the housing, then the insulating 
wall is expediently applied so that it separates a corner region as an 
insulating shaft together with the side walls of the housing. 
In another case, it is also expedient that the insulating wall extends in 
the form of a tube jacket from the aeration opening in the interior of the 
housing. The cross section of the tube can be circular, rectangular, or of 
another arbitrary shape. It is possible to utilize any unused cavities in 
the interior of the housing as an insulating shaft without increasing the 
volume of the housing. However, if possible, the aeration opening and the 
insulating shaft should be applied optimally close to the switching 
contacts since that is where the aeration is most effective for increasing 
the useful life of the electromechanical component. 
Since the aeration opening is usually provided in a wall at the upper side 
of a cap composed of insulating material, it is expedient to also directly 
apply the insulating wall which forms the insulating shaft to the cap.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows a relay housing in partial cross section, whereby a pedestal 1 
having two stationary contact elements 2 and 3 as well as a middle contact 
spring 4 are shown merely schematically within the interior of the 
housing. The actuation of the contacts occurs in the usual way and thus is 
not described in detail here. 
Together with a cap 5, the pedestal 1 forms a housing for the relay that is 
also sealed at its underside with casting compound 14. To create an 
aeration opening 6, a wall 5a at an upper side of the housing is provided 
with a shoulder 5b at a corner on which a severable peg or bleb 7, also 
referred to as a "nip-off pin", is provided. A channel which forms the 
aeration opening 6 after the bleb 7 has been severed is provided within 
the bleb extending from inside the housing. 
A printed circuit board 8 is also shown schematically in FIG. 1, arranged 
above the relay housing. The printed circuit board 8 includes a voltage 
carrying terminal pin 9, which accidentally, or otherwise, comes to lie 
above the aeration opening 6 of the relay housing. In this case, it can 
thus be assured that the air path, or insulating path 10, shown by a 
dotted line in FIG. 1 extending between the pin 9 and the contact elements 
2 and 3 in the interior of the relay is adequately long to guarantee the 
required safety against electrical sparking and arc-overs. A sufficiently 
long air path is guaranteed in that an insulating shaft 11 is formed in 
the interior of the housing connected to the aeration opening 6. An 
additional insulating wall 12, which is shown integrally formed with the 
cap 5, provides the insulating shaft 11. 
By referring to FIG. 2 it can be seen that the aeration opening 6 lies at a 
corner of the relay housing. The insulating shaft 11 thus likewise is 
limited to the housing corner and is formed by the insulating wall 12 
together with small sections of the side walls 5c and 5d of the housing 
cap 5. Together, these wall sections separate a small volume of air in the 
housing interior to form the insulating shaft 11. The shape and arrangement 
of the wall is shown in FIG. 2 cutting generally diagonally across the 
corner of the housing, with small end sections extending perpendicular to 
each respective side wall. The aeration opening 6 is initially closed to 
keep out contaminating agents during the manufacturing and soldering of 
the relay and is subsequently opened by cutting off the bleb 7 to free the 
aeration opening 6. 
In FIG. 3 is shown a further development of the invention in which a 
further partition 13 is applied to the pedestal 1 in addition to the 
insulating wall 12 molded in the cap 5. The insulating path 10 is thereby 
further lengthened as shown to form a labyrinth like, or convoluted, air 
path by of the overlap between the insulating wall 12 and the partition 
13. 
A further possible embodiment of the invention is shown in FIG. 4 in which 
only a housing cap 15 is merely shown, in cross section. The illustrated 
cap 15 has a weakened or thin section 16 somewhere in the middle region of 
its upper side which may be penetrated to obtain the desired aeration 
opening. An insulating shaft 17 in the form of a tube as applied to the 
cap 15 under and in communication with the weakened section 16. The 
insulating shaft is formed by an insulating wall or tube jacket 18 in this 
case. The position of the particular tubular insulating shaft 17 is 
dependent upon the special relationships and arrangements of the 
components available within the component housing. 
Thus, there is shown and described a component housing for a relay or the 
like which an aeration opening discharging into an interior of the housing 
and provided with an insulating shaft separated from any metallic parts in 
the housing by an insulating wall which extends from the housing wall. The 
insulating shaft is open to the housing interior at an end opposite the 
aeration opening. This provides sufficiently long insulating paths between 
voltage carrying components in the housing interior and neighboring 
metallic parts outside of the housing. 
Although other modifications and changes may be suggested by those skilled 
in the art, it is the intention of the inventor to embody within the 
patent warranted hereon all changes and modifications as reasonably and 
properly come within the scope of his contribution to the art.