Switching devices, such as switchgears, are also designated as switching magnets, are disclosed, for example, in DE 36 35 551 A1 and DE-GM 83 17 753, and are readily obtainable on the market. The switching component is made up essentially of a tubular bolt which, when the coil undergoes electric excitation, traverses a predetermined path to the plug receptacle of a connector plate, thereby initiating a switching process, for example, in the case of a valve blocking and allowing the passage of fluid flows. If such switching devices are used in areas of high humidity, such as occurs among other situations in formation of condensate, the moisture advances to the interior of the housing, and especially to the coil element with the winding. The moisture leads to disabling of the switching device as corrosion occurs. While it has already been proposed to avoid this problem by enclosing the housing of the switching device entirely in a plastic sealing compound providing protection from moisture, this proposal results in an overly large switching device ill suited for use in automotive technology (mobile technology), where in essence only little installation space is available.
FR 1 348 792 proposes using rubber sealing rings (O rings) mounted on the end in seats of housing covers of the switching device and between the housing and the plug receptacle of the connector plate to effect sealing potential points of entry of moisture into the housing, rather than by sealing a plastic sealing compound. In this instance as well, however, it has been found that the sealing from penetration of moisture, in particular in the area of the plug connector of the connector plate, is not satisfactory. Embrittlement of the sealing rings, which may accompany aging of the switching device, results in complete destruction of the sealing effect.
Another magnetic coil configuration is disclosed in DE 198 54 100 A1. An encapsulated coil with a spray-applied plug socket is provided for connection of electric connection leads. A metal housing encloses the encapsulated coil. The contact lug associated with the protective lead connection extends through the plug socket, and is connected to the metal housing. To prevent entry of moisture into the sealed space of the plug socket as a result of capillary action between the contact lug and the plastic enclosing it, a recess is provided between the plug socket and the outer surface of the encapsulated coil, into which the metal housing is introduced. A connecting element, which effects electric connection of the contact lug with the metal housing, extends through the recess inside the plug socket. A sealing element enclosing the connecting element is mounted in the recess in the plug socket. Magnetic coil configurations such as this are employed in industrial hydraulics for actuation of electromagnetically operated hydraulic valves in which metal parts accessible from the exterior are to be connected to a grounded lead connection.
For a generic switching device disclosed in DE 43 41 087 C2, an attempt has been made to solve this problem where the plug receptacle has a contact surface for application of an annular sealing component. The contact surface projects a predetermined axial distance beyond the bottom of the connector plate facing the external circumference of the housing. When installation has been completed, at least the gap between connector plate and the external circumference of the housing is closed to effect sealing by applying pressure to the annular rubber sealing element. In this way, moisture can no longer reach the interior of the housing, and in particular the coil element with the winding. This solution is costly to implement. The parts in question must interact with minimal tolerances, something which appreciably increases manufacturing complexity and consequently manufacturing costs. In addition, since a rubber sealing ring is used, when the switching device is in service over a long period failure from embrittlement or loosening of the sealing ring in question cannot be excluded.