GB2160362A

GB2160362A - Electromagnetic device

Info

Publication number: GB2160362A
Application number: GB08513724A
Authority: GB
Inventors: Klaus Greefe; Richard Kommert; Rudolf Sellner; Erwin Muders
Original assignee: BBC BROWN BOVERI and CIE; Brown Boveri und Cie AG Germany
Current assignee: BBC BROWN BOVERI and CIE; BBC Brown Boveri AG Germany
Priority date: 1984-06-13
Filing date: 1985-05-31
Publication date: 1985-12-18
Also published as: GB2160362B; GB8513724D0; EP0166266B1; AU4360685A; EP0166266A3; DE3421874A1; NZ212394A; EP0166266A2; IN161869B; AU586427B2; DE3583545D1

Description

SPECIFICATION Electromagnetic device An electromagnetic device is an apparatus in which mechanical movement is caused by varying an electrical current through the device. Such devices are often called Electromagnetic Trigger devices when they cause movement when the electric current exceeds a threshold value.

Such trigger devices have application in lowvoltage switch gear where they trigger a latching switch. They may be used for protection against short circuits. They usually have a hinged armature magnet.

The response value can be adjusted by a spring which engages on the rotor. The electromagnetic trigger devices are ofgreat importance for the operation of current limiting circuit breakers and quick-break switches.

A hinged armature magnet is known from French Patent 1513052. In this case, the hinged armature is mounted in such a way that it is mounted on two correspondingly formed pins disposed in front ofthe yoke knife edge by means of two rectangular recesses cut in the hinged armature, and is secured by means of a tension spring which engages behind the yoke knife edge on the hinged armature. The tension spring determines atthe same time the rest position of the hinged armature. It can be seen that the hinged armature is only secured in its mounting in the direction of the pins by the tension spring. This proves to be disadvantageous, since in certain circumstances, e.g. in the case ofshockofthetriggerdevice, the hinged armature can spring out of its mounting. A corresponding strengthening ofthetension spring is not possible, because the response value of the hinged armature magnet and therefore the trigger device is adjusted by means of the tension spring force.

The aim of the invention is to improve the hinged armature mounting in the case of a hinged armature magnet of the type described above in orderto increase operating safety.

This aim is achieved by the electromagnetic device

Claims

of claim 1. The advantages obtained with the invention consist in particular in that the hinged armature remains secure in its mounting independently of the mounting position of the hinged armature magnet and in the case of shock. Further, an exact rest position ofthe hinged armature with a defined air gap is achieved by the hinged armature mounting according to the invention, as is necessary in order to obtain a constant, exact response value forthe trigger device. Further advantageous developments of the invention are covered in the sub-claims. The invention is explained below with the aid of an embodiment illustrated in the drawings, in which: Fig. lisa side view of a hinged armature magnet in the rest position; Fig. 2 is a side view of the hinged armature magnet according to Fig. 1, in the operating position; Fig. 3 is a section in the plane Ill-Ill of the hinged armature magnet; Fig. 4 is a rear view of the hinged armature magnet. Fig. 1 shows a hinged armature magnetforan electromag netic trigger device which is not described in detail. The hinged armature magnet 1 has a rectangularly bent yoke 2 comprising a low retentivity substance (iron). On the inside of one yoke limb a cylindrical iron core 3 is secured, on which a coil 4 is pushed. The free end of the other yoke limb is formed in the manner of a shoulder by means of a web-like extension 8thereofwhich is disposed in the centre. The shoulders are slanted on their rear facets in such a way that the outer edges form a knife edge5 (Figure 2). The hinged armature 6 has two limbs 16which are disposed at one end in the shape of a fork. The hinged armature 6 is mounted in such a way that the limbs 16 are supported on the yoke knife edge and for lateral locking receivetheweb-like extension 8 between themselves in a matching manner. Below the hinged armature6thereisa limiting pin 9 which is integrally formed on the web-like extension 8, and which holds the hinged armature 6 on the yoke knife edge 5. Further,the endsofthe limbs 1 6 of the hinged armature 6 are provided with engaging studs 10 which engage behind the yoke knife edge 5. The engaging studs 10 are integ rally formed on the hinged armature by means of a shearing action during the punching process. An anchoring spring 12, designed as a tension spring, is suspended in a borehole 11 arranged asymmetrically on the hinged armature 6 and secured by its other end to a transverse pin 13 of the web-like extension 8 of the yoke 2. The anchoring spring 12 which engages on the hinged armature 6 holds the latter in the rest position in which the hinged armature assumes the "open" position, i.e. is not attracted. In the case of a shortcircuitthe hinged armature magnet 1 responds in the shortest time possible and the hinged armature is attracted. Atrigger lever 14 of a latching switch, which is not described in detail, is moved into position 15 by means of the hinged armature 6 moving to the operating position (Fig. 2), and the latching switch is thus unlocked, the contacts of the switchgearopened and the short circuit current switched off. There is of course also the possibility of designing the hinged armature magnet 1 in such a way that, on triggering the hinged armature 6 is moved, in the reverse direction, by the spring 12 out of the "attracted" position (Fig. 2) in which the hinged armature rests against the iron core 3, into the "release" position (Fig. 1), in which the hinged armature is at a distance from the iron core 3, the hinged armature thereby actuating the latching switch. The mounting thus remains unchanged. CLAIMS

1. An electromagnetic device comprising a rectangularly bent yoke, a coil with an iron core secured on a limb of the yoke, with a knife edge on the otheryoke limb, a limiting pin beyond the knife edge, a hinged armature mounted between the yoke knife edge and the limiting pin, the armature being formed with an engaging stud to engage one side of the knife edge in ordertolockthehingedarmaturetogetherwiththe yoke, and a spring to bias the armature in one direction aboutthe knife edge.

2. A device as claimed in Claim 1 wherein the yoke has a web-like extension beyond the knife edge and the hinged armature is forked atone end so asto be supported on the yoke knife edge by both its fork limb ends with the web-like extension disclosed between theforked limbendsforlateral securing.

3. A device as claimed in Claim 1 or Claim 2 whereinthe engaging stud isformed intergrallyon the hinged armature by means of a shearing action during a punching process.

4. A device as claimed in any one of Claims 1 to 3 wherein the limiting pin is integral with saidweb-like extension.

5. An electromagnetic device substantially as herein before described with reference to and as illustrated in the accompanying drawings.