AU713111B2

AU713111B2 - Armature for magnetic trigger

Info

Publication number: AU713111B2
Application number: AU11321/97A
Authority: AU
Inventors: Adolf Tetik
Original assignee: Felten and Guilleaume Austria AG
Current assignee: Felten and Guilleaume Austria AG
Priority date: 1995-12-28
Filing date: 1996-12-18
Publication date: 1999-11-25
Anticipated expiration: 2016-12-18
Also published as: SK88698A3; CZ199398A3; HU222336B1; HUP9901164A2; PL181900B1; GR3032197T3; DE59603247D1; AU1132197A; HUP9901164A3; PL327232A1; SK285089B6; WO1997024746A1; EP0870315A1; AT410858B; ATE185219T1; NO982912L; NO982912D0; CZ287121B6; ATA211195A; EP0870315B1

Abstract

The invention relates to an armature (10) for magnetic trigger mechanisms (1) for safety switches, in particular for automatic cut-out switches, which comprises a sheet-metal strip which is formed to produce a sleeve of circular-ring cross-section. The ends (20) of said strip are aligned in relation to the armature (10) axis and lie close to each other at least in places. The stop for driving the tripping tappet(14) is a tongue (12) which along with the sheet-metal strip forms one member and is aligned transversely to the axis of the armature (10). To keep the air gap in the joint region (21) of the sleeve as small as possible, the edges (20) in the joint region (21) of the armature (10) can rest flatly against each other.

Description

1 ARMATURE FOR MAGNETIC TRIGGER 0O *c 5 S. 0 5

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The present invention relates generally to armatures for actuating the release of magnetic triggers for safety switches. In particular, the invention relates to an armature having a metal strip formed into a sleeve and a stop for carrying with it a trigger ram.

Currently, armatures used in magnetic triggers for safety switches are manufactured predominantly by a metal machining process. This is not only a time-intensive and cost-intensive manufacturing method, which is associated with not inconsiderable material losses, but the armatures for safety switches manufactured in this way have a comparatively high mass which disadvantageously influences the response characteristic of the magnetic trigger fitted with such an armature.

An armature of the type initially described above is known from DE25 31 215 A, in which the edges of the metal strip rolled in to the armature do not touch 15 one another at the meeting point. In addition to this the stop for entraining the trigger ram on the armature is formed by a recess in which a formed shape of the armature ram engages. The disadvantage to this known armature is that the metal strip end surfaces running in the direction of movement of the magnetic armature form an armature slot and are arranged at a distance from one another 20 such that eddy currents are minimised. Such an armature with the desired air gap is, as trials have demonstrated, unsatisfactory in magnetic triggers.

The object of the invention is to make available a simple-to-manufacture and effective armature for magnetic triggers for safety switches.

The present invention accordingly provides an armature for actuating a 25 trigger ram of a magnetic trigger for a safety switch, the armature including a metal strip shaped into a sleeve and a stop for carrying with the sleeve the trigger ram, wherein edges of the metal strip running parallel to the axis of the armature at least partially touch one another at a meeting point and wherein the stop includes at least one tab which is aligned transversely to the axis of the armature and is formed integrally with the armature.

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~ik J iii: i' ~l__jii The proposed armature for magnetic triggers according to the present invention can be manufactured not only by shaping, for example in a rolling process, from a corresponding strip section, a punched blank, for instance, but also offers the advantage of a smaller mass than previously used armatures manufactured by metal machining. In addition, it has shown up surprisingly that the armature according to the present invention is of considerable advantage in magnetic triggers, because there is no air gap present to influence the magnetic properties of the armature since the edges of the metal strip rolled into the armature touch one another at least partially.

The tab of the armature according to the present invention, which serves as a cam for the trigger ram, enables simple construction of the trigger ram and, l if required, can be made as usual, since the necessary shaping in the prior art DE 25 31 215A is not required.

Further advantages, characteristics and details of the invention will 15 emerge from the following description, in which reference is made to the S accompanying diagrams.

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s 25 so Figure 1 shows a magnetic trigger in cross-section, Figure 2 shows in partial cross-section the magnetic trigger without guide sleeve, armature and trigger ram, Figure 3 shows in partial cross-section and on an enlarged scale the structural unit of guide sleeve, armature according to the present invention and trigger ram as well as reset spring, Figure 4, 5 and 6 show in partial section an armature according to the present invention, and Figure 7 shows another embodiment of the armature according to the present invention.

Magnetic triggers 1 having the known structure illustrated in Figure 1 are utilised in automatic cutouts. They consist of a yoke 2 made of a magnetically conductive material to which bracket 4, comprised of an electrically conductive II material, of fixed contact 3 of the automatic cutout is connected. Further, magnetic trigger 1 has a field winding 5 which is connected electrically conductively by way of terminals (not illustrated here) to the line to be protected.

Set in the interior of coil 5 is a guide sleeve 6, most frequently made of synthetic material which is patched by means of a sleeve-shaped stop 7 connected to yoke 2 of magnetic trigger 1. By way of example this sleeve-shaped stop 7 is connected by flanging of its tapered projection 8 with yoke 2 and bracket 4 made of electrically conductive material, whereby at the same time the connection is made between electrically conductive bracket 4 carrying fixed contact 3 and yoke 2.

Arranged in guide sleeve 6, as in Figure 3, is an armature 10 made from a magnetically conductive material which can slide displaceably and which has Sat its end 11 averted from stop sleeve 7 an inwards projecting stop which is formed in the embodiment by a tab 12 and on which end 13 of a trigger ram 14 15 accommodated inside armature 10 is supported. Placed over front section 15 of

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"0 ,6 trigger ram 14 is a recuperating spring 16 which lies with its front end 17 on end 18 of stop sleeve 7 taken up in the interior of magnetic trigger 1 and which holds trigger ram 14 in its ready position illustrated in Figure 3.

When triggering occurs, when the magnetic field generated by coil 5 is adequate, armature 10 is drawn to the right of Figure 1 and in the process entrains trigger ram 14 over its tab 12, such that the latter actuates with its front end 19 a trigger mechanism (not illustrated here), by means of which and in a manner known in and of itself a movable contact is raised from fixed contact 3 o°°6° S and the automatic cutout consequently interrupts the current.

As illustrated in Figures 4, 5 and 6 armature 10 used in accordance with the proposal of the invention in above-described magnetic trigger 1 or a magnetic trigger of similar construction, is made from a punched sheet section having essentially rectangular contours which is formed into a ring or a sleeve.

Here the punched sheet section is formed into a ring, or sleeve, such that edges 20 aligned parallel to the axis of armature 10 lie closely on one another and such that at meeting point 21 of these edges 20 there is no, or only minimal, air gap. To ensure that edges 20 parallel to the axis of the metal strip formed into _ii_ ilii//l/_i__ armature 10 lie closely on one another, during manufacture of armature 10 from the metal blank it can be bent over so that edges 20 of the metal blank running in an axial direction can also at least partially lie closely on one another in finished armature 10 and there is no air gap disadvantageously influencing the magnetic properties of the armature.

For the purpose of entraining trigger ram 14 accommodated inside armature 10 in the event of triggering with movement of armature 10 (at least one) tab 12, angled radially inwards, is provided which in the embodiment shown is formed integrally with the metal strip forming actual armature On both sides of root 25 of tab 12 bent at right angles there are recesses 26 provided such that root 25 of tab 12 can be bent in such a way that tab 12 running transversely to the axis of armature 10 does not project beyond S° adjacent end surface 27 of armature In the embodiment of armature 10 illustrated in Figure 5 edges 20 are aligned flush on one another. This may be achieved simply by these edges being designed at an incline during manufacture or punching of the sheet metal section to the plane of the (not yet deformed, therefore flat) sheet metal section.

SWith this particular embodiment there is not an air gap in the region of meeting point 21 for practical reasons.

In the embodiment of armature 10 according to Figure 7 edges 20 meet at a small sharp angle and touch each other only in the region of their inner edges 28. The air gap in the vicinity of meeting point 21 is so small here also that essentially it does not disadvantageously influence the desired magnetic properties of armature In principle any magnetically conductive material is suitable to be used for armature Soft magnetic materials have proven to be especially suitable, as known for direct current relays. The preferred soft magnetic materials have a magnetic saturation of 1.4 to 2.0 T at a field strength of 4000 A/m. An especially preferred material for armature 10 according to the present invention is the material described in DIN 17 405 (September 1979) with RFe80 (materials number 1.1014), which has a magnetic saturation of 1.6 T at a field strength of 4000 A/m.

In summary, a preferred embodiment of the invention can be represented as follows: An armature 10 for magnetic trigger 1 for safety switches, especially for automatic cutouts, comprises a metal strip shaped into a sleeve having a circular cross-section, whose edges 20 aligned with the axis of armature 10 lie in close contact with one another at least partially. The stop for entraining trigger ram 14 is a tab 12 designed integrally with the metal strip and aligned transversely to the axis of armature 10. In order to keep the air gap in the vicinity of meeting point 21 of the sleeve as small as possible, edges 20 can lie flush on one another in the region of meeting point 21 of armature 0

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Claims

1. An armature for actuating a trigger ram of a magnetic trigger for a safety switch, the armature including a metal strip shaped into a sleeve and a stop for carrying the trigger ram with the sleeve, wherein edges of the metal strip running parallel to the axis of the armature at least partially touch one another at a meeting point and wherein the stop includes at least one tab which is aligned transversely to the axis of the armature and is formed integrally with the armature.

2. An armature as claimed in Claim 1, wherein the metal strip is rolled into a sleeve having a circular cross-section. *6 0 1

3. An armature as claimed in Claim 1 or 2, wherein the tab forms a right angle with the wall of the armature and is bent inwards.

4. An armature as claimed in any one of Claims 1 to 3, wherein the root of the tab lying in the wall of the armature is punched free on both sides through recesses. OO.•

5. An armature as claimed in any one of Claims 1 to 4, wherein the tab is arranged inside an end surface, adjacent to the tab, of the sleeve forming the armature.

6. An armature as claimed in Claim 5, wherein an outer surface of the tab lies flush with the adjacent end surface of the armature. 0 °a

7. An armature as claimed in any one of Claims 1 to 6, wherein the edges of the metal strip formed into the armature lie flush on one another in the vicinity of the meeting point.

8. An armature as claimed in Claim 7, wherein edge surfaces of the metal strip in the region of the edges are inclined to the plane of the metal strip when the metal strip is still flat.

9. An armature as claimed in any one of Claims 1 to 6, wherein the edges of the metal strip formed into the armature lie with inner edges touching one another in the vicinity of the meeting point.

An armature as claimed in Claim 9, wherein edge surfaces of the metal strip in the vicinity of the edges are aligned normally with the plane of the metal strip when the metal strip is still flat.

11. An armature as claimed in any one of Claims 1 to 10, wherein the 0 S• armature includes a soft magnetic material having a magnetic saturation of 1.64 to 2.0 T at a field strength of 4000 A/m. 0

12. An armature as claimed in Claim 11, wherein the magnetic saturation is approximately 1.6 T at a field strength of 4000 A/m.

13. An armature as claimed in any one of Claims 1 to 12, wherein the armature consists of the material RFE 80 according to DIN 17 405. 0.0

14. An armature substantially as herein described with reference to Figures 3-7 of the accompanying drawings. DATED this 23rd day of September 1999 00 FELTEN GUILLEAUME AUSTRIA AG *4 WATERMARK PATENT TRADEMARK ATTORNEYS 290 BURWOOD ROAD HAWTHORN VICTORIA 3122 AUSTRALIA DOC 28 AU1132197.WPC SKP:RLT:SLB K^^ ,7 I