Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
BACR~:ROUND OF THE INVE:NTION
The invention is directed to a contact spring set for high
electrical currents having two elongated contact elements that have
thair respective main parts arranged approximately parallel. The
respective one ends of these contact elements are fastenad and
their respective opposite free ends are movable relative to one
another for the purpose of contacting.
Such a contact spring set of a traditional prior art type is
shown in Figure 3 in terms of its fundamental structure. A
stationary contact spring 21 and a movable contact spring 22 are
each respectively clamped in a carrier 23 at one side. They carry
cont~ct pieces 24 and 25 in the proximity of their free ends, these
contact pieces 24 and 25 touching one another in one switch
position, and thus producing contact. The movable contact spring
22 is thereby pressed against the stationary contact spring 21 (in
the direction of the ar--ow 27) by an actuation member 26, as a
result whereof the contact force is produced. The contact force
could also be produced hy a corresponding prestress of the movable
contact spring 22, which would then yield a normally closed
contact. An actuation memher would then have to act opposite the
arrow 27 for opening the contact.
When, given a closed contact according to the illustration in
Figure 3, a high current i flows across the two contact springs 21
and 22, then an electrodynamic force that is indicated by the arrow
28 results~ due to the two opposite current flows in the contact
springs. This electrodynamic force attempts to press the two
contact springs apart. When the contacting force exerted via the
actuation member 26 or by a prestress is not adequate, then the
electrodynamic forces can lead to an opening of the contacts. As
2~9~2
long as the magnet systems of high-current relays were designed
correspondingly large, adequately high contacting forces were
always produced in any case so that the electrodynamic open~ng
forces did not take effect. Due to the general miniaturization
even of relays for high breaking capacities given simultaneous
reduction of the control power, the necessary contacting forces for
carrying high pulsed currents may no longer be produced und~r
certain circumstances with the magnet system that has been reduced
in terms of its volume. As mentioned, the parallel contact springs
are pressed apart by the electrodynamic forces, so that an opening
of the contacts occurs during the current pulse. ~his results in
a high-power arc ~,hat can lead to a welding of the contacts. Such
pulse currents, for example, can be short-circuit currents of 1000
A, whereas the relay itself is designed only for a constant current
of, for example ~ A.
In order to control this problem, considerably larger relays had
to be previously employed than would ~lave been necessary for the
constant current to be carried. The only other possibility was in
accepting a welding of the contacts, given a short-circuit.
8UMMARY OF ~E _NVEN~ION
It is an object of the invention to create a contact spr'ing set
of the type initially cited that resolves the aforementioned
problem, whereby no opening of the contacts due to the
electrodynamic forces is possible, even given the occurrence of
extremely high currents.
This object is achieved according to the invention in that the
contacting section of the first contact elemsnt is provided at a
clip-shaped section bent off from the main part which embraces the
second contact element. This is provided such that the contacting
210'~9~2
section of the second contact element lies between th2 ~ain part
and the contacting section of the Eirst contact element.
In the invention, thus the contacting location between the two
contact elements is turned, so to speak, toward the outside away
from the parallel contact elements due to a corresponding, bow-
shaped design of a contacting section. Thus, the contacting
location no longer lies between the main parts of the two contact
elements or contact springs, but lies at the outside of the one
contact element. The switch motion and the direction of the
contacting force are thus turned around, so that the electrodynamic
forces between the main parts of the two contact ~lements no longer
oppose the contacting force, but even internsify it.
BRIEF_DE8CRIPTION OF THE DRAWINGa
Figure 1 is a contact spring set designed according to the
invention, and shown schematically in a side view;
Figure 2 is a somewhat modified contact spring set shown in a
perspectlve view; and
Figure 3 is a side view oE a contact spring set of thP prior art
already set forth above.
~CRIPTION OF THB PREFERRED ~MBODIM2N~
The contact spring set de~cribed in Figure 1 has a stationary
contact spring 1 and a movable contact spring 2, both of which have
their one end anchored in a carrier 3 and a main longitudinally
extending part. The free end 2a of the movable contact spring is
bent U-shaped around the free end la of the stationary contact
spring, so that the contacting section 2b has its contact piece 5
residing opposite the outside of the stationary contact spring with
its contact piece 4. The U-shaped section is thus formed of a
middle segmQnt which is perpendicular to the main longitudinally
~ ~ 2~19~
extending main part of the contact element 2, and of an end segment
serving as the contacting section 2b.
The closed condition of the contact shown in Figure 1 is procluced
by an actuation member 6 that is moved in the direction of the
arrow 7 and thus produces the contacting force. When an extremely
high pulsed current i is not sent through the closed contact,
electrodynamic forces 8 take effect that attempt to press the main
parts of the contact springs 1 and 2 apart. Since the contacting,
however, occurs between the outsides of the stationary contact
spring 1 and the bent-off section 2b, the electrodynamic forces act
in the direction of the contacting force and intensity it.
The principle of reversing the direction of the contactin~ force
shown in Figure 1 can also be analogously applied for modified
contact spring sets, and for break contacts as well.
The contact spring set of Figure 1 c70uld thus be operated as a
break-contact if the contact spring 2 were pre-stressed in the
direction of the arrow 7. The contact could then be opened in the
direction of the arrow 7' with an actuation member 6'.
Figure 2 shows a futher example of a break-contact. Here, a
stationary contact spring 11 is arranged together with a movable
contact spring 12 such that a section lla bent of in bow-shaped
fashion carries a contacting section llb at the outside of the
movable contact spring 12. The contact pieces 14 and 15 in the
illustrated example are in contacting contact with one another
since this involves a break contact, i.e. a prestress in the
direction of the arrow 17 holcls the contact closed in the quiescent
condition. This contact can be opened with an actuation member 16
upon actuation. In this case too, a current pulse, together with
the electrodynamic forces resulting therefrom, acts in the sense
of closing the contact, so that a chattering or arc is also thus
avoided.
Although various minor changes and modifications might be
proposed by those skilled in the art, it will be understood that
I wish to include within the claims of the patent warranted hereon
all such changes and modifications as reasonably come within my
contribution to the art.
