Electromagnetic relay

The relay has a T-shaped core and a U-shaped armature, the transverse web of the latter being mounted on the free end section of the core longitudinal limb, and the free ends of its longitudinal arms forming two parallel operating air gaps with respect to the transverse limbs of the core. In this way, particularly simple assembly and an operating air gap with large pole areas can be achieved using a small number of simple parts.

BACKGROUND OF THE INVENTION 
The invention relates to an electromagnetic relay having 
a coil winding which is arranged on a coil former between coil flanges, 
a T-shaped core having a longitudinal limb and two transverse limbs, the 
longitudinal limb extending axially through the coil former, 
a U-shaped armature having two longitudinal arms, which run on both sides 
of the coil, and a transverse web, a first end section of the armature 
being mounted in the region of a first coil flange on an end section of 
the core, and its second end section forming an operating air gap with the 
core in the region of the second coil flange, and 
having a contact arrangement having at least one stationary contact element 
and at least one moving contact spring, the contact spring being operated 
by the armature via an operating device which can be moved transversely 
with respect to the coil axis. 
Such a relay has been disclosed, for example, in DE 34 43 094 A1. There, 
the T-shaped core is expanded into an E-shape or M-shape by projections of 
the ends of the transverse limbs, which extend parallel to the center 
limb. The U-shaped armature is mounted at the ends of its longitudinal 
arms on these projections of the core, so that its transverse web forms 
the operating air gap with the free end of the center limb of the core. 
This type of armature mounting on an E-shaped core always involves 
additional bearing elements in the form of a bearing spring, which not 
only involves corresponding complexity during production with stamping and 
bending, but also during assembly with corresponding adjustment and 
riveting or welding processes. However, such an armature cannot be secured 
in its mounting in any other way. In addition, there is only a relatively 
small pole area in the operating air gap between the armature transverse 
limb the core end, and this pole area cannot readily be enlarged, either. 
SUMMARY OF THE INVENTION 
The aim of the present invention is to design a relay of the type mentioned 
initially such that it can be assembled in a particularly simple manner 
using only a small number of parts which are of simple design and are easy 
to produce, in which case it is nevertheless possible to achieve reliable 
operation and a high pull-in reliability by virtue of a relatively large 
pole area in the operating air gap. 
The same is achieved according to the invention in that the armature is 
mounted via its transverse web on the free end section of the longitudinal 
limb of the core, and in that the free ends of the armature longitudinal 
arms form two parallel operating air gaps with the free ends of the core 
transverse limbs. 
Thus, in comparison to the known relay, the armature mounting and the 
operating air gap are arranged interchanged in the relay according to the 
invention, so that the U-shaped end of the armature encloses the first 
coil flange and is thus secured just by virtue of its arrangement in the 
longitudinal direction of the coil axis. Since the armature can also be 
secured in other directions in the region of a coil flange by simple 
structural design, there is no need for any bearing spring, with its 
corresponding production and assembly effort. On the other hand, the two 
parallel operating air gaps at the free ends of the armature permit a 
relatively large pole area. This pole area can additionally be enlarged by 
the core transverse limbs each being provided at their ends with 
projections in the direction of the armature longitudinal arms, so that 
the T-shape of the core is expanded, as indicated, into an M-shape or an 
E-shape. 
In order to secure the armature in its mounting, the first coil flange in a 
preferred embodiment has an attachment, and this attachment and the 
armature have projections and/or recesses which engage in one another. The 
armature can then be further secured in its mounting by a housing cap that 
is plugged on. 
The contact spring that is operated by the armature is preferably arranged 
approximately parallel to the coil axis on the side of the coil opposite 
the armature, and the armature movement is transmitted to the contact 
spring by a slide which is guided between the transverse limbs of the core 
on the one side and the adjacent coil flange on the other side, such that 
it moves at right angles to the coil axis. An attachment on the said 
housing cap can also provide additional guidance for the slide. 
The first coil flange can have a projection in the form of a base beyond 
the attachment for the armature mounting, which base defines a base plane 
which the coil axis extends at a right angle. The at least one contact 
spring and the at least one mating contact element are then expediently 
anchored at right angles to the base and plane in the base, associated 
connecting pins are passed through the base to the exterior, at right 
angles. At least one stop is preferably provided on the second coil flange 
for the contact-making ends of these contact elements, and this stop 
defines the rest position of the mating contact element and/or of the 
contact spring. 
The moving ends of the armature longitudinal arms are preferably 
pre-stressed away from the core into a rest position by means of a 
resetting spring force and, furthermore, a fulcrum is preferably in each 
case provided in the center region of these longitudinal limbs, and by 
means of a stop on a housing part, the resetting spring force forces the 
transverse web of the armature into its bearing on the core. This ensures, 
even without any bearing spring, that the armature has the smallest 
possible air gap to the core in its rest position, resulting in good flux 
transfer and high pull-in sensitivity. Since this resetting spring force 
is preferably applied by the contact spring, the number of individual 
parts in the relay can be kept particularly small. The fulcrum in the 
center region of the armature can be produced by shoulders (which are 
integrally formed at the sides) on the armature longitudinal arms in 
conjunction with a corresponding rib or groove on the inside of the 
housing cap, so that no additional parts or assembly processes are 
required. 
The invention will be explained in more detail in the following text with 
reference to an exemplary embodiment and using the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The relay illustrated in the drawing comprises a coil former 1, a T-shaped 
or approximately M-shaped core 2, a U-shaped armature 3, a slide 4 in the 
form of a card, a stationary contact spring 5, a moving contact spring 6, 
a cap 7 as well as two coil connecting pins 8 which are anchored in the 
coil former. 
The coil former 1 has an axial through-opening 11 as well as a first flange 
12 and a second flange 13, between which a winding 10 is fitted. At the 
end, an attachment 14 for armature mounting is integrally formed on the 
coil flange 12, and merges into a base plate 15. Furthermore, limiting 
pins 16 for the armature are integrally formed on the attachment 14 and, 
furthermore, plug-in slots 17 are formed in this attachment, through which 
plug-in slots 17 the connecting elements 51 and 61, respectively, of the 
contact springs 5 and 6 can be passed through the base plate 15, at right 
angles, to the exterior. Furthermore, a stop tab 18 for the stationary 
contact spring 5 is integrally formed on the second coil flange 13. 
The T-shaped core 2 has a longitudinal limb 21 which is introduced into the 
through-opening 11 in the coil former, as well as two transverse limbs 22, 
to each of whose ends side arms 23 are fitted, parallel to the 
longitudinal limb 21. The U-shaped armature 3 comprises two longitudinal 
arms 31 and a transverse web 32, the latter of which is mounted on the 
free end section 24 of the core 2 and is then located in a recess between 
the first coil flange 12 and the base plate 15. The two securing pins 16 
of the base attachment 14, which engage in corresponding recesses 33 in 
the armature, ensure that the armature is secured against lateral 
movements, without this impeding its switching movement. The free ends of 
the longitudinal arms 31 are broadened to form hook-shaped pole ends 34 
which engage around the second coil flange 13 and form two parallel 
operating air gaps with the transverse limbs 22 as well as their side arms 
23 of the core. 
The stationary contact spring 5 and moving contact spring 6 are anchored in 
the plug-in slots 17 in the base attachment 14 by means of their 
connecting elements 51 and 61, respectively, which are integrally formed 
or are attached in a known manner. In the present example, the two contact 
springs 5 and 6 are of identical design and are provided with end sections 
53 and 63 (FIG. 3) which have respective contacts 52 and 62. The mutual 
overlap in order to make contact is provided by an L-shaped bend at their 
moving, contact-making ends. 
The contact springs 5 and 6 are just cut from a flat metal sheet without 
bending, and are inserted into the coil former. The mutual offset between 
their contact-making ends results simply from the geometry of the coil 
former and of the slide 4. This slide is located between the coil flange 
13 and the transverse limbs 22 of the core. It has a recess aperture or 
opening 41 through which the core longitudinal limb 21 is passed. Once the 
parts have been joined together, the end section 53 (which is bent in an 
L-shape) of the stationary contact spring 5 (see FIGS. 2 and 3) rests on 
the stop tab 18 on the coil former 1, and is thus given its rest 
pre-stressing. On the other side, the end section 63 (which is bent in an 
L-shape) of the moving contact spring 6 rests on the slide 4. When the 
slide 4 is operated by the armature, the end section 63 is moved in the 
direction of the end section 53 of the stationary contact spring 5, and 
lifts the latter off its stop on the tab 18. This is how the contact force 
is produced. 
After assembly of the described individual parts, the cap 7 is fitted over 
the relay. It forms a closed housing with the base plate 15. As can be 
seen from FIG. 4, the cap 7 has in the region of its top a ventilation 
hole 71 which opens into an inwardly projecting attachment 72. The latter 
attachment forms an additional guide for the slide 4. As can also be seen 
from FIG. 4, the armature 3 is pre-stressed via the slide 4 into its rest 
position by means of the resetting force of the operating contact spring 
6. In this case, lateral shoulders 35 on the armature abut against ribs 72 
on the cap, forming a fulcrum 73 for the armature. The mounted end or the 
transverse web 32 of the armature is forced by the lever effect, via this 
fulcrum 73, into the bearing and against the end section 24 of the core. 
This results in reproducible flux transfer conditions in the armature 
mounting, and correspondingly low pull-in excitation.