Relay with bridge contact spring

An electrical relay assembly has a spring action bridge contact for engaging with two counter contact elements. The bridge contact is connected with an armature at one end of a longitudinal first section. The other end of the first section is connected to a linearly directed second section having two contact points facing opposite the counter contact elements. The first section has a lateral width not greater than the distance between the contact points. A lever action of the contact points about two different axes thereby results, as a consequence of which a frictional effect is produced at the contact points. The bridge contact is particularly applicable for the switching of low currents.

BACKGROUND OF THE INVENTION 
The invention relates to an electrical relay with an excitation coil, an 
armature, and at least two counter contact elements, provided with 
connection elements, which are adjacently arranged in one plane, in which 
the counter contact elements are electrically bridged by a bridge contact 
actuatable by the armature which has a spring action about two different 
axes. 
The utilization of bridge contacts has long been conventional in the case 
of contactors and heavy current relays. A double contact interruption, 
which can be achieved with a bridge contact activated by an armature 
stroke, is of particular advantage in the case of switching high currents. 
In the known bridge contact constructions the bridge contact is 
customarily switched by the armature via an actuation slide which engages 
the bridge approximately in the center between the two contact points. In 
the case of this central actuation virtually no frictional movement, or 
rolling movement, in the region of the contact points results. During the 
switching of high currents this may not be necessary since, in the case of 
contacts, great contact forces, or switching forces, are in play anyway 
through which a reliable contact making and a reliable contact separation 
is assured. 
In the case of weak or low-voltage current contact relays, the trend to 
increasingly smaller models inevitably leads to the contact clearances 
becoming smaller. However, the switching capability, particularly in the 
case of inductive loads, is also thus reduced. The application of bridge 
contacts, in spite of a small armature stroke, could improve switching 
capability; however, standing in the way of an application of bridge 
contacts conventional in the case of contactors are the disadvantages that 
the contact resistances, due to double contact interruption, are 
comparatively high, particularly if films of foreign material form on the 
contact surfaces. In the case of purely perpendicular contact actuation 
without frictional movements and rolling movements, such films of foreign 
material can not be rubbed off, so that the contact forces which are 
comparatively small in midget relays no longer suffice for a good contact 
making. 
It is an object of the invention to provide a relay with bridge contacts 
such that it is suited for the switching of very small currents and 
exhibit a long life. The relay is practical over a wide load range 
extending from very small currents to very large currents. In addition, an 
embodiment of such a relay is to be produced which, pursuant to 
application of the inventive principles, is constructed very simply and 
with few parts and can likewise be sealed so as to be liquid-tight in a 
simple fashion. 
SUMMARY OF THE INVENTION 
A contact relay is provided with a bridge contact fixed at one end in 
operative connection with the armature and having two contact points 
arranged at the free end of the bridge contact disposed opposite the 
counter contact elements. The bridge contact is formed with a longitudinal 
first section having a lateral width which corresponds to no more than 
half the distance between the two contact points. The two contact points 
are arranged offset on a second linear section relative to the 
longitudinal axis of the first section such that, upon touching of the 
counter contacts, a spring lever action about the first section's clamping 
axis as well as an additional spring lever action about an axis offset to 
the clamping axis can be obtained. 
In the inventive relay, through the design and arrangement of the bridge 
contact, a thrust-friction-rolling-movement on the contact points is 
produced which arises through the two generally perpendicular spring lever 
actions between clamping of the spring on the armature and the counter 
contact elements. Through this frictional movement films of foreign 
material, which would otherwise increase the contact resistance, are 
penetrated through during switching and simultaneously, the foreign 
particles disposed on the contact surfaces are also rubbed away. During 
the connection of DC current, uneven locations produced due to the 
occurring material migration are leveled immediately during occurrence. 
In one embodiment the bridge contact is designed in T-formation, whereby it 
is clamped on the armature with one end of the base leg and bears the 
contact points, respectively, at the free ends of the cross leg. In 
another embodiment, the bridge contact spring can possess a longitudinal 
first leg which is clamped on the armature with one end and which supports 
at its free end, at least on one side, a second contacts leg via a lateral 
intermediate bar. The bridge contact can also be designed to be 
meander-shaped along the first section with lateral cut-outs occurring 
between the clamping point and the contact points. 
The contact-frictional movement intended with the invention is particularly 
favorable obtained if the clamping first section axis of the bridge 
contact is laterally offset relative to the armature rotational axis. The 
counter contact elements may emerge in one plane from a base member and 
through oppositely angled sections to form contact points which are one 
over the other in one plane. The bridge contact may be provided with a 
second section contact element such that a double contact making between 
the bridge contact and two, parallel-switched counter contact elements can 
be achieved. The application range of the relay for small and large 
switching loads is thereby substantially expanded. 
A further application of the inventive principle is in the case of a relay 
in which the coil has its axis is arranged horizontally and the armature 
is arranged essentially parallel to the coil axis. The bridge contact 
extends over the entire coil length above the plate shaped armature. In 
the region of a first coil flange, a terminal lug running perpendicularly 
to the coil axis is connected to one end of the bridge contact and the 
other end of the bridge contact, in the region of an opposite second coil 
flange, is disposed opposite the two counter contact elements which extend 
perpendicularly to the coil axis at their connection elements on opposed 
sides of the second coil flange, and which, with their contact-making ends 
disposed opposite the bridge contact spring, are bent oppositely relative 
to one another into a common plane. Such a relay can be simply 
manufactured from a few parts. 
With the bridge contact spring above the coil, air paths and leakage paths 
necessary for high currents can be well-realized. The bridge contact 
disposed above the coil, prior to the application of a housing cap, is 
easily accessible from the exterior for the purpose of adjustment. 
Adjustment of a synchronous contact making on both contact points on the 
bridge contact can be made by bombardment with laser beams, for example, 
such as taught in German OS No. 2,918,100. 
The plate-shaped armature is mounted with one end on a leg of the coil 
core, which upwardly bent in U-formation, and connected with the bridge 
contact via an intermediate insulating part. This insulating part can be 
formed through extrusion coating or other embedding of the armature. 
However, it is also possible to connect the armature with the insulating 
part through plugging. In an expedient embodiment, the insulating part 
exhibits a flexible leg running parallel to the terminal lug portion of 
the bridge contact and serves as reset spring for the armature. This 
flexible leg can be supported against an offset tongue of the bridge 
contact in the region of the terminal lug. On the opposite end of the 
insulating part a projecting leg can likewise be provided in order to 
insulate the armature against the counter contact elements. 
In a further embodiment the armature is arranged with the bridge contact 
within the coil along the coil axis. The bridge contact possesses, at the 
end face before the second coil flange, a cross leg with which it is 
disposed opposite the counter contact elements. The bridge contact can be 
connected with the armature in a suitable manner. In this case, a U-shaped 
yoke with its center portion outside the coil is so arranged that a yoke 
leg serves the purpose of bearing the armature and the second yoke leg 
forms, with the armature, the operating air gap. The bridge contact is 
anchored in the first coil flange to simultaneously serve as the armature 
reset spring.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 shows a T-shaped bridge contact 1, such as is suitable for an 
electrical contact relay for the switching of weak or low voltage current. 
It is clamped in a support 2 at one end of a longitudinally extending 
first leg 1a. The support 2 is fixedly connected with a non-illustrated 
movable armature. The bridge contact 1 is thus actuated via this support 2 
and not via a separate contact slide. A transverse second leg 1b possesses 
at the ends contact points or rivets 3 and 4 which cooperate with 
respective counter contact elements. 
Through this construction and the type of actuation a double spring lever 
action can be obtained on the bridge contact 1. Acting as lever arm in 
longitudinal direction is the leg 1a having a lever arm length via which a 
thrust-friction-rolling-movement on the contact points can be obtained. 
Acting perpendicularly thereto is the cross lever action of the transverse 
leg 1b, in which the lever, in relation to the first leg longitudinal 
axis, amounts to half the width b between the two contact points 3 and 4. 
Both levers become effective due to the armature actuation during the 
contact making and during the contact opening, whereby a friction movement 
with rubbing and clamping effects are obtained on the contact points. 
The bridge contact 1 with an electric connection element renders a relay 
particularly well-adapted to various switching problems. As, shown in FIG. 
2, for example, a double contact making can be obtained, whereby the 
switching voltage U is applied between the connections of the bridge 
contact 1, on the one hand, and parallel-connected counter contact 
elements 5 and 6, on the other hand. Such a double contact making 
increases switching safety, particularly in the case of switching of small 
loads. 
As shown in FIG. 3, a switching voltage U may be connected between the two 
counter contact elements 5 and 6 so that the bridge contact 1 is merely 
employed as a contact bridge without a separate connection. In this case 
double the contact clearance obtainable in the case of a bridge contact is 
utilized. 
As shown in FIG. 4, a switching voltage U is again connected between the 
bridge contact 1 and the two counter contact elements 5 and 6. These 
counter contact elements, however, are not directly parallel-connected; 
rather, a resistance 7 is connected in series with the counter contact 
element 5. Moreover, the counter contact element 5 possesses a smaller 
contact clearance d1 in comparison to the contact clearance d2 of the 
counter contact element 6 relative to the bridge contact 1. The counter 
contact element 5 thus serves as a precursor contact which switches 
earlier. This arrangement can be of advantage in the case of high current 
peaks. 
FIG. 5 schematically illustrates a sample embodiment for the application of 
the inventive bridge contact assembly in an electrical contact relay with 
a pivotable armature 8 which is mounted via an insulating support 9 on a 
base member 10. Connected to the armature 8, via the support 9, is a 
T-shaped bridge contact comprising a longitudinal portion 11 and a cross 
piece 11a. The longitudinal portion 11 is fixedly clamped in the support 9 
and jointly participates in the switching movements of the armature 8 
about its rotational axis 12. Two counter contact elements 13 and 14 are 
anchored in one plane in the base member 10. At their free ends they are 
respectively bent off at an angle relative to one another such that they 
form counter contact points 13a and 14a, respectively, which are disposed 
above one another in one plane. The counter contacts 13a and 14a cooperate 
with the cross piece 11a of the bridge contact 11. The contact element 
profiles 15 are respectively applied over the entire width of the 
contact-making parts 13a, 14a, and 11a, so that they are disposed in a 
cross shape above one another and guarantee reliable contact making during 
the occurring frictional movement. 
A somewhat modified embodiment of the inventive bridge contact assembly 16 
is shown in FIG. 6 in which a longitudinal portion 16a is anchored at one 
end in the support 9. This portion 16a supports, at its free end, via a 
crossbar 16b, a contact bridge portion 17 which has a linear axis 
extending parallel to the longitudinal portion 16a and, with its two free 
ends, respectively, makes contact with two spaced-apart counter contact 
elements 18 and 19. The double spring lever action of this contact bridge 
again results about an axis passing through the anchor point 20 as well as 
relatively about the longitudinal axis of the portion 16a. 
An intensified frictional movement is provided in the embodiments according 
to FIGS. 5 and 6 in that the clamping point 20 possesses a relatively 
large clearance a in relation to the armature rotational axis 12. During 
switching the bridge contact 16 thereby executes a relatively large 
movement in its longitudinal direction which results in a corresponding 
frictional movement on the contact points. 
FIG. 7 shows a further version of the inventive bridge contact assembly 
having a meander-shaped longitudinal base portion 21, having lateral 
cut-out spaces 22 and 23. A twice cross-sectional reduction thus occurs 
between the crosspiece contact bridge 24 and the anchor point 25 
preferably to approximately one-third of the spring width to save 
material. 
A modified embodiment of the inventive bridge contact 26 is shown in FIG. 
8. Therein, at the free end of the longitudinal base portion 26a, a pair 
of contact legs 28 are formed on opposed free ends of a crossbar 27. The 
individual contact legs 28 together generate, as a contact bridge, the 
additional spring lever action in relation to the clamping point 29. 
In FIGS. 9 through 11, a simple, compact or midget electrical contact relay 
is shown in which one of the above-described bridge contacts can be 
employed. The relay possesses a base member 31 which simultaneously serves 
as coil member for a winding 32. In the coil member a U-shaped core 33 is 
arranged whose two lateral legs 34 and 35 respectively lie adjacent spaced 
coil flanges 36 and 37. This core 33 can expediently be injected into the 
base member 31. Also, the coil can be extrusion-coated with plastic. On 
the core leg 34 an armature 38 is mounted which is disposed in 
plate-shaped fashion above the coil, parallel to the linear axis of the 
coil. The opposed free end of the armature 38, with its free end, forms a 
working movement air gap 39 with the core leg 35. 
The armature 38 is supported in an insulating material part 40 which, for 
example, can be formed through extrusion coating of the armature. This 
insulating material part 40 could, however, also accommodate the armature 
through plugging-in or another type of mounting. Disposed above the 
insulating material part 40 is a bridge contact 41 which extends 
perpendicularly over the entire coil length and which is fixedly connected 
via the insulating part 40 with the armature 38. For mounting, for 
example, pins, bars, or other extensions can be provided on the insulating 
material member 40, which extensions, through heat deformation on the 
lateral edge or in recesses of the spring 41, retain the latter. The 
bridge contact 41, in the region of the coil flange 36, is downwardly bent 
at a right angle and thus forms a terminal lug 42 which is plugged through 
a recess 43 of the base member 31 and is anchored there with a tongue 
portion 44 bent off at an angle. A free leg 45 of the insulating material 
part 40, which leg is disposed in the region of the coil flange 36, serves 
as reset spring for the armature. The lower end of the leg 45 is supported 
via a nose tip 47 on a bent-out tongue 48 of the bridge contact 41. 
The free end of the bridge contact 41 which, for example, can be designed 
to have a T-formation according to FIG. 1, bears a contact profile 49 
which cooperates with two counter contact elements 50 and 51. These two 
counter contact elements, with their connection parts 50a and 51a, are 
respectively arranged laterally of the coil flange 37 and, with their 
contact making ends 50b and 51b, are bent in a common plane beneath the 
bridge contact spring 41. They are additionally insulated from the 
armature, and the core, through the leg 52 of the insulating material part 
40. Through the lateral arrangement of the counter contact element a good 
heat transfer to ambient is provided. The coil flange 37 is formed, in the 
region between the two counter contact elements, with a chamber 53 for the 
accomodation of a getter tab 54 which is mounted between lamellar ribs 55 
in the base member. These lamellae form additional insulating paths 
between the counter contacts which cannot be readily bridged even by 
melted or burn off products. 
The relay is closed by a cap 56 of plastic which is placed in inverted 
position over the base member 31. The cap is sealed on the lower side with 
a fleece 57 which is saturated with synthetic resin. A rib 58 formed on 
the cap serves to limit the stroke of the armature, and the bridge contact 
spring 41. Moreover, the contact spring may be adjusted from above, for 
example, with laser beams, prior to application of the cap. 
A further modified embodiment is shown in FIG. 12. In this case the coil 
member 61 forms a continuous axial cavity 62 in which a rod-shaped 
armature 63 is arranged. A U-shaped yoke 64 is inserted from below in 
recesses of the coil member 61 such that it forms a bearing point for the 
armature 63 with its leg 65 in the region of the coil flange 66, whereas 
the leg 67 in the region of the coil flange 68 forms a working air gap 
with the armature. 
Connected with the armature 63 is a bridge contact spring 69 which, over 
the entire length of the coil tube, is disposed above the armature, and, 
with its leg 70, bent off at an angle, serving as terminal lug, is 
anchored in the coil flange 66. Through suitable pre-stress the bridge 
contact spring can simultaneously serve as a reset spring for the 
armature. The bridge contact spring may also be designed in T-formation 
also in this case, whereby the cross leg 71 is disposed at the end face 
before the coil winding in the region of the coil flange 68 and forms two 
contact points opposite two counter contact elements 72. The counter 
contact elements 72, like the counter contact elements 50 and 51, are 
laterally mounted on the coil flange and their contact making ends are 
bent off at an angle into a horizontal plane beneath the contact leg 71 of 
the bridge contact spring. Over the contact points a getter tab 73 is 
mounted in a suitable manner in the coil member. This relay is also closed 
with a cap 74. 
Although various minor modifications may be suggested by those versed in 
the art, it should be understood that I wish to embody within the scope of 
the patent warranted hereon all such modifications as reasonably and 
properly come within the scope of my contribution to the art.