MAGNET ARMATURE, CONTACTOR HAVING A MAGNETIC ARMATURE, AND METHOD FOR SWITCHING A CONTACTOR

Abstract

The invention specifies a magnet armature for a contactor, a contactor, and a method for switching a contactor. The magnet armature allows the risk of the contacts of a contactor sticking to be reduced and to this end comprises a first spring element with a first stiffness and a second element with a second stiffness. The first spring element is deformed during the movement from an inoperative position to a central position. The second spring element is deformed during the movement from the central position to an end position.

Claims

1. A magnet armature, comprising a first spring element with a first stiffness k1, a second spring element with a second stiffness k2, an inoperative position, an end position and a central position between the inoperative position and the end position, wherein the first spring element is provided to be elastically deformed during the movement from the inoperative position to the central position, but not during the movement from the central position to the end position, the second spring element is provided to be elastically deformed during the movement from the central position to the end position, but not during the movement from the inoperative position to the central position.

2. The magnet armature according to claim 1, wherein the first spring element and the second spring element are arranged in series.

3. The magnet armature according to claim 2, further comprising a bush between the first spring element and the second spring element.

4. The magnet armature according to claim 3, further comprising a cylindrical section which the first spring element, the bush and the second spring element coaxially surround, wherein the end of the first spring element which faces the bush is provided to move relative to the cylindrical section during the movement from the inoperative position to the central position, but not during the movement from the central position to the end position, the bush and that end of the second spring element which faces the bush are provided to move relative to the cylindrical section during the movement from the central position to the end position, but not during the movement from the inoperative position to the central position.

5. The magnet armature according to claim 1, wherein a movement from the inoperative position to the end position corresponds to a displacement by a distance h=h1+h2 which is between 1.5 and 2.5 mm long, and the movement from the inoperative position to the central position constitutes a displacement by h1, and the movement from the central position to the end position constitutes a displacement by h2.

6. The magnet armature according to claim 1, wherein a movement from the inoperative position to the central position corresponds to a displacement by a distance h1 which lies in an interval of between 0.4 times and 0.6 times the distance h=h1+h2 of the displacement from the inoperative position to the end position.

7. The magnet armature according to claim 1, wherein 3.3?k2/k1?3.6.

8. The magnet armature according to claim 1, wherein 0.5 N/mm?k1?0.9 N/mm and 2.3 N/mm?k2?2.7 N/mm.

9. The magnet armature according to claim 1, comprising a cylindrical section and further comprising a contact stamp and a magnetizable material, wherein the contact stamp comprises an electrically conductive material and, in its end position, is provided to interconnect two electrical contacts, and the magnetizable material comprises iron, cobalt or nickel.

10. The magnet armature according to claim 1, wherein the cylindrical section has a first subsection with a first diameter, a second subsection with a second diameter and a step between the two subsections, the step between the two subsections constitutes a fourth stop, and the fourth stop constitutes a stop for the bush.

11. The magnet armature according to claim 10, wherein the bush touches the fourth stop during the movement from the inoperative position to the central position, and the bush does not touch the fourth stop during the movement from the central position to the end position.

12. The magnet armature according to claim 11, wherein the bush decouples the two springs at least in one position.

13. A contactor (SCH), comprising a magnet armature according to claim 1 having a bush between the two spring elements, a yoke and a guide with a mechanical stop, wherein the magnet armature and the yoke form an electromagnetic actuator which is provided to move the magnet armature relative to the yoke and to the guide, the bush does not touch the mechanical stop in positions between the inoperative position and the central position, the bush touches the mechanical stop in positions between the central position and the end position.

14. The contactor according to claim 13, wherein the guide has a third stop, the third stop constitutes a limit for the movement of the magnet armature, and the magnet armature, in its inoperative position, touches the third stop.

15. A method for switching an electromagnetic contactor having a solenoid, a contact stamp, a first spring element and a second spring element, comprising the steps of: activating the solenoid in an inoperative position, accelerating the contact stamp against the restoring force of the first spring element up to a central position, moving the contact stamp against the restoring force of the second spring element up to an end position.

16. The magnet armature according to claim 2, wherein a movement from the inoperative position to the end position corresponds to a displacement by a distance h=h1+h2 which is between 1.5 and 2.5 mm long, and the movement from the inoperative position to the central position constitutes a displacement by h1, and the movement from the central position to the end position constitutes a displacement by h2.

17. The magnet armature according to claim 3, wherein a movement from the inoperative position to the end position corresponds to a displacement by a distance h=h1+h2 which is between 1.5 and 2.5 mm long, and the movement from the inoperative position to the central position constitutes a displacement by h1, and the movement from the central position to the end position constitutes a displacement by h2.

18. The magnet armature according to claim 2, wherein a movement from the inoperative position to the central position corresponds to a displacement by a distance h1 which lies in an interval of between 0.4 times and 0.6 times the distance h=h1+h2 of the displacement from the inoperative position to the end position.

19. The magnet armature according to claim 3, wherein a movement from the inoperative position to the central position corresponds to a displacement by a distance h1 which lies in an interval of between 0.4 times and 0.6 times the distance h=h1+h2 of the displacement from the inoperative position to the end position.

20. The magnet armature according to claim 2, comprising a cylindrical section and further comprising a contact stamp and a magnetizable material, wherein the contact stamp comprises an electrically conductive material and, in its end position, is provided to interconnect two electrical contacts, and the magnetizable material comprises iron, cobalt or nickel.

Description

[0048] The operating principle and exemplary embodiments are shown with reference to schematic figures and explained in greater detail below.

[0049] FIG. 1: shows a cross section through a simple embodiment of a magnet armature MA in its inoperative position,

[0050] FIG. 2: shows a cross section through a simple embodiment in its central position,

[0051] FIG. 3: shows a cross section through a simple embodiment of the contactor in its end position,

[0052] FIG. 4: shows a cross section through an embodiment of a magnet armature with a spring element for tolerance compensation and with a contact stamp,

[0053] FIG. 5: shows a cross section through a contactor with a magnet armature and with a contact stamp, a first electrode and a second electrode in a gas-filled hollow space, corresponding to the examples of FIGS. 5 and/or 6.

[0054] FIG. 6: shows a cross section through an embodiment of a magnet armature MA with a third A3 and a fourth stop A4,

[0055] FIG. 7: shows a cross section through the embodiment of FIG. 6 in the central position,

[0056] FIG. 8: shows a cross section through the embodiment of FIG. 6 in the end position,

[0057] FIG. 1 shows the cross section through a simple embodiment of a magnet armature MA in its inoperative position RP. The magnet armature MA has a first spring element F1 and a second spring element F2. The two spring elements F1, F2 determine the restoring forces during the movement from its inoperative position to its end position. In particular, the first spring element F1 determines the restoring force during the movement from the inoperative position to the central position. The restoring force during the movement from the central position to the end position is determined by the spring stiffness of the second spring element F2. In this case, h1 is the length of the distance which is covered during the movement from the inoperative position to the central position. In this case, h=h1+h2 is the length of the distance which is covered during the movement from the inoperative position to the end position.

[0058] FIG. 1 shows, in addition to the magnet armature MA, a guide F? which limits the movement of the armature during the movement between the positions to a displacement along an axis. The guide F? can therefore constitute a guide rail with a first stop A1. A bush B is arranged between the first spring element F1 and the second spring element F2. The magnet armature MA has a cylindrical section ZA. The first spring element F1, the second spring element F2 and the bush B are arranged coaxially around the cylindrical section ZA.

[0059] The contact stamp KS is arranged at one end of the cylindrical section ZA. A magnetizable material M is arranged at the other end of the cylindrical section ZA. If the magnet armature MA, shown horizontally, moves to the left relative to the guide F?, the spring element with the lower spring stiffness, here the first spring element F1, is substantially compressed. If the second spring element F2 has a considerably higher spring stiffness or the second spring element F2 is under a pretension which is greater than the tension of the first spring element F1 in the central position, the second spring element F2 is not compressed or compressed only to an insignificant extent during the movement from the inoperative position RP to the central position MP. In this case, the bush B moves by the distance h1, until the bush B strikes the first stop A1, during the movement from the inoperative position RP to the central position MP. During this phase of the movement, the restoring force which acts on the magnet armature MA is provided substantially or exclusively by the spring stiffness of the first spring element F1.

[0060] FIG. 2 shows the magnet armature in its central position MP. In this case, the bush B touches the first stop A1. If the magnet armature is further moved to the left relative to the guide F?, the bush B is supported on the first stop A1, so that the first spring element F1 cannot be compressed further. The second spring element F2 is necessarily compressed during the further movement.

[0061] Accordingly, FIG. 3 shows the magnet armature in its end position EP. In this case, the second spring element F2 is compressed until the magnet armature reaches its end position which can be prespecified, for example, by a second mechanical stop A2.

[0062] The magnet armature is now located in a position in which an electrical switch which forms part of the magnet armature is closed by two electrodes touching the contact stamp.

[0063] A short closing time can be achieved during closing since the solenoid has to work only against the weak restoring force of the first spring element F1 and as a result can be rapidly accelerated, in particular in the critical initial phase. Rapid opening of the electrical switch is achieved by the second, stronger restoring force of the second spring element F2 immediately taking effect during deactivation of the solenoid.

[0064] Therefore, overall, a magnet armature is specified which allows both rapid closing and also rapid opening and which reduces, in particular, the burning time of an arising arc and the risk of the contacts sticking.

[0065] FIG. 4 shows an embodiment of the magnet armature MA in which a displaceable bush B is likewise arranged between a first spring element with a first spring stiffness k1 and a second spring element with a second spring stiffness k2. The rear end of the magnet armature MA has, in the direction of the contact stamp KS, a conical raised portion which is arranged coaxially around a cylindrical section of the contact stamp. The associated guide has a correspondingly shaped conical recess which faces the end of the armature. A self-centering guide is therefore obtained when the switch is closed. A further spring element FTA, which can compensate for vertical tolerances and generates the actual contact force, is arranged between the contact stamp KS and the remaining section of the armature MA. A section which is composed of an insulating material IM is arranged between the further spring element FTA and the remaining section of the armature in order to DC-isolate the electrical contacts, which are to be connected by means of the contact stamp KS, and the magnet armature.

[0066] FIG. 5 shows a cross section through a possible embodiment of a contactor SCH in its inoperative position RP. In addition to the magnet armature with its magnetizable material M, the contactor SCH has a yoke J in which electrical windings of a coil SP are arranged. FIG. 5 additionally shows a hollow space HR in which ends of a first electrode and of a second electrode are situated opposite the contact stamp KS. If the magnet armature is moved initially against the resistance force of the first spring element and subsequently against the stronger resistance force of the second spring element, the contact stamp KS is pushed against the ends of the two electrodes EL1, EL2, as a result of which the two electrodes EL1, EL2 are interconnected with one another. A gas, for example a noble gas, is contained in the hollow space HR in order to extinguish an arc as quickly as possible, in particular when the contact is opened, in order to protect the material of the electrodes and of the contact stamp KS.

[0067] FIG. 6 shows an embodiment of the magnet armature MA with a fourth stop A4 and an embodiment of the contactor SCH with a third stop A3, in each case in the inoperative position RP. The position of the armature MA and the guide F? in the inoperative position RP is determined by the third stop A3.

[0068] FIG. 7 shows an embodiment of the magnet armature MA with a fourth stop A4 and of the contactor SCH with a third stop A3 in the central position MP. This position constitutes a moment in the movement sequence in which the second spring element F2 is active.

[0069] FIG. 8 shows an embodiment of the magnet armature MA with a fourth stop A4 and of the contactor SCH with a third stop A3 in the end position EP. The position of the armature MA and of the guide F? in the end position EP is determined by the second stop A2.

[0070] The following is clear from FIGS. 6, 7 and 8: in order to realize a defined value for h1 independently of the ratio of the spring rates and in order to decouple the spring forces, the cylindrical section ZA has the fourth mechanical stop A4 in the form of a step in the diameter. As a result, the second spring element F2 and the first spring element F1 are decoupled during a phase during activation until the central position of the contactor SCH is reached. In particular, the mechanical stops one, A1, and four, A4, decouple the springs F1, F2.

[0071] The invention specifies a contactor which, in spite of its magnet armature being of complex construction, has an improved electrical performance, can comply with customary geometric dimensions and therefore can be easily integrated into existing external circuit environments.

[0072] Neither the magnet armature nor the contactor nor the method for switching the contactor are limited to the exemplary embodiments shown. Magnet armatures with additional stops, apparatuses for pretensioning, in particular, the second spring element, and further measures for reducing the loading on the electrodes of a contactor constitute subjects according to the invention.

LIST OF REFERENCE SYMBOLS

[0073] A1: First mechanical stop [0074] A2: Second mechanical stop [0075] A3: Third mechanical stop [0076] A4: Fourth mechanical stop [0077] B: Bush [0078] EL1: First electrode [0079] EL2: Second electrode [0080] EP: End position [0081] F1: First spring element [0082] F2: Second spring element [0083] FTA: Spring element for tolerance compensation [0084] F?: Guide [0085] h: Distance of the length of the movement from the inoperative position to the end position [0086] h1: Distance of the movement from the inoperative position to the central position [0087] h2: Length of the distance of the movement from the central position to the end position [0088] HR: Hollow space [0089] IM: Insulating material [0090] J: Yoke [0091] KS: Contact stamp [0092] M: Magnetizable material [0093] MA: Magnet armature [0094] MP: Central position [0095] RP: Inoperative position [0096] SCH: Contactor [0097] ZA: Cylindrical section [0098] ZA1: First subsection [0099] ZA2: Second subsection