Field of the Invention
The invention relates to a contact spring. The contact spring includes the following parts: a bottom spring with a centrally disposed spring arm base formed by a rectangular frame, a connection part formed on one end of the spring arm base for electrical conductors, and two spring arms adjoining an opposite end and formed onto broad sides of the spring arm base. The spring arms converge toward one another on a free end and then open into a plug-in funnel. Respective indentations facing one another and disposed on long edges keep the spring arms spaced apart, in the vicinity of a contact zone. A detent sleeve connected to the spring arm base surrounds the spring arms.
It is well known that in disconnectable electrical contacting devices, in particular plug devices of the kind formed by a female part, such as a contact spring, and a connecting part, such as a contact blade, the contact force is of decisive significance for the reliability of the electrical connection.
There is also a demand for contact surfaces capable of good conduction, that is, which are not corroded or are non-scaling, so as to assure interference-free current transfer at the contact surface and to minimize the contact resistance.
Furthermore, disconnectable contacts constructed as a plug device should be simple to manipulate, both in the manufacture of the electrical terminals and in making the plug connection.
German Published, Non-Prosecuted Patent Application DE 196 11 698 A1 discloses a contact spring of the type defined at the outset, with resilient contact legs on both sides for contact blades intended to carry high current, in which the above demands are maximally met. However, in the use of that known contact spring, it has been found that while the contact force is still at about greater than 3 N after a certain number of plug-in operations and thus does not fall below the specified holding force for an introduced blade contact, nevertheless the requisite plugging force rises to approximately 10 N, thereby making manipulation more difficult. Under some circumstances, that can make the connection defective, or if the holding force is too low the connection can come loose or be interrupted.