Electrical switching device with locking function

Abstract

Disclosed is a switching device having an electromagnetic actuation device for driving a movable contact, which actuation device has an excitation coil for generating a magnetic field, a magnetic yoke for amplifying the flux density of the magnetic field, and a magnet armature which can be pulled from a starting position to a pulled position by the magnetic field and which is connected to the movable contact. The actuation device includes a locking element which at least partly consists of a ferromagnetic material and is arranged such that by virtue of the effect of the magnetic field, the locking element is brought from the unlocking position to the locking position. The magnetic yoke is designed to have a discontinuity when the locking element is in the locking position, and the discontinuity of the magnetic yoke is closed by the locking element when the locking element is in the unlocking position.

Claims

1. A switching device comprising at least one stationary contact and a movable contact cooperating therewith, and comprising an electromagnetic actuation device for driving the movable contact, wherein the electromagnetic actuation device comprises an excitation coil for generating a magnetic field, a magnetic yoke for amplifying the flux density of the magnetic field, and a magnet armature configured to be pulled by the magnetic field from a starting position to a pulled position and connected to the movable contact, wherein the electromagnetic actuation device further comprises a locking element movable from a locking position, in which the locking element prevents movement of the magnet armature and/or the movable contact, into an unlocking position, in which the locking element releases a movement of the magnet armature and/or of the movable contact, wherein the locking element consists at least partially of a ferromagnetic material and is configured so as to be transferred from the unlocking position into the locking position due to the action of the magnetic field, wherein the magnetic yoke is configured such that the magnetic yoke has a discontinuity when the locking element is in the locking position, the discontinuity of the magnetic yoke being closed by the locking element when the locking element is in the unlocking position, and wherein the magnetic yoke comprises an upper yoke plate and a lower yoke plate that are arranged parallel to and spaced apart from one another and substantially perpendicular to the magnet armature and between which the excitation coil is arranged, the locking element being arranged on the two yoke plates such that the two yoke plates are completed to form a U-shaped section when the locking element is in the unlocking position.

2. The switching device according to claim 1, wherein the electromagnetic actuation device is configured to amplify the magnetic flux acting on the magnet armature when the discontinuity of the magnetic yoke is closed by the locking element.

3. The switching device according to claim 2, wherein the electromagnetic actuation device is configured to pull the magnet armature against the force of a return spring of the electromagnetic actuation device when the magnetic yoke is closed, whereas the magnetic flux acting on the magnet armature is insufficient to pull the magnet armature against the force of the return spring when the magnetic yoke is interrupted.

4. The switching device according to claim 1, wherein the locking element is configured in the manner of a swivel armature.

5. The switching device according to claim 1, wherein the locking element is biased into the locking position by a resetting element, preferably in the form of a pretensioning spring.

6. The switching device according to claim 1, wherein a direction of movement of the locking element extends transversely to a direction of movement of the magnet armature.

7. The switching device according to claim 6, wherein the direction of movement of the locking element forms an angle of 70 to 90 with the direction of movement of the magnet armature.

8. The switching device according to claim 1, wherein the locking element has a projection that cooperates with a back taper formed on the magnet armature or on the movable contact to lock or release the magnet armature and/or the movable contact.

9. The switching device according to claim 8, wherein the projection in the locking element is configured in the form of an elongated hole extending essentially perpendicular to the magnet armature, the magnet armature extending through the elongated hole and the magnet armature having an annular groove that forms the back taper and cooperates with the elongated hole in the locking element for locking or unlocking the magnet armature.

10. The switching device according to claim 1, wherein the locking element is formed in several parts and has an activating part and a locking part, the locking part and the activating part being hingedly connected to one another.

11. The switching device according to claim 10, wherein the activating part and the locking part form an angle of 80 to 100 with one another, the locking part being arranged essentially parallel to the two yoke plates and an elongated hole being formed in the locking part.

12. The switching device according to claim 1, wherein the locking element in its locking position locks the magnet armature in the starting position.

13. The switching device according to claim 10, wherein the at least one stationary contact and the movable contact cooperating therewith are open when the magnet armature is in the starting position.

Description

(1) In the drawings:

(2) FIG. 1: shows a schematic section through a switching device according to the invention with the magnet armature in the starting position and the locking element in the locking position,

(3) FIG. 2: shows the switching device according to the invention as shown in FIG. 1 with the magnet armature still in the starting position and the locking element in the unlocking position,

(4) FIG. 3: illustrates the switching device according to the invention from FIGS. 1 and 2 after unlocking the magnet armature with the magnet armature in the pulled position,

(5) FIG. 4: is side view of a second embodiment of a switching device according to the invention with the magnet armature in the starting position and the locking element in the locking position, and

(6) FIG. 5: is a perspective view of the switching device of FIG. 4 after unlocking the magnet armature with the magnet armature in the pulled position.

(7) For the following embodiments, identical parts are indicated by identical reference signs. If a figure contains reference signs that are not described in detail in the associated figure description, reference is made to previous or subsequent figure descriptions.

(8) FIG. 1 shows a schematic section through a switching device 1 according to the invention. The switching device 1 has two stationary contacts 2 and a movable contact in the form of a contact bridge 3. In the illustration of FIG. 1, the electrical contacts are open.

(9) The switching device 1 also has an electromagnetic actuation device for driving the movable contact 3. The electromagnetic actuation device has an excitation coil 4 for generating a magnetic field that acts on a magnet armature 6 configured as a tie rod. The excitation coil 4 is wound on a bobbin 14. The tie rod 6 is connected at its upper end to a contact carrier 11, which in turn is connected to the contact bridge via corresponding contact pressure springs 13.

(10) The electromagnetic actuation device further has a magnetic yoke for amplifying the magnetic flux acting on the armature 6. The magnetic yoke has a U-shaped section 5 surrounding the excitation coil on three sides. The two legs of the U-shaped section 5 cover the two end faces of the hollow cylindrical bobbin 14. The two legs have corresponding bores 15, through which the magnet armature 6 extends. At the open end of the U-shaped section, a likewise ferromagnetic locking element 7 is hinged to the lower leg of the U-shaped section. The locking element 7 is designed in the manner of a swivel armature and is arranged on the U-shaped section 5 of the magnetic yoke so that it may be pivoted via the joint 8.

(11) In the starting position of the magnet armature 6 shown in FIG. 1, the locking element 7 is initially in a locking position when the excitation coil is switched off. For this purpose, the locking element 7 has an outwardly projecting nose 10 at the free end, which is latched with a hook 12 projecting from the contact carrier 11. Upon switching off the actuation device the locking element 7 is reliably held in the locking position by a pretensioning spring 9, which in the example shown is configured as a tension spring and is fastened to a housing element not shown herein.

(12) Upon energizing the excitation coil 4, the locking element 7, which is configured as a swivel armature, is attracted by the U-shaped section 5 of the magnetic yoke due to the magnetic flux, so that the free end of the locking element 7 moves towards the free end of the upper leg of the U-shaped section 5. The hook 12 is thereby released, unlocking the magnet armature. The locking element 7 is now in an unlocking position. At the same time, the locking element 7 thereby closes the magnetic yoke of the excitation coil (FIG. 2), so that the magnetic flux acting on the magnet armature is increased and the magnet armature is moved from the starting position to the pulled position (FIG. 3) against the force of a return spring (not shown), so that the electrical contacts are closed.

(13) FIG. 4 shows a side view of a further embodiment of a switching device 1 according to the invention in the locking position of the locking element 7. In this position, the contact points of the switching device 1 are open (OFF position). The structure of the switching device 1 according to the second embodiment essentially corresponds to the structure of the switching device shown in FIGS. 1 to 3. Therefore, only the differences will be referred to in the following. For elements of the switching device 1 according to the second embodiment that are not described, reference is made to the preceding description of FIGS. 1 to 3.

(14) According to the embodiment shown in FIG. 4, the magnetic yoke includes two yoke plates, an upper yoke plate 5.1 and a lower yoke plate 5.2. The two yoke plates 5.1, 5.2 are arranged parallel to each other. Bolts 17 extending perpendicular to the yoke plates 5.1, 5.2 are arranged between the two yoke plates 5.1, 5.2 and hold the yoke plates 5.1, 5.1 at a distance from each other. The bolts 17 are connected to the two yoke plates 5.1, 5.2. The bolts 17 are preferably made of a non-magnetic steel or plastic. Tests have shown that bolts made of magnetic materials also show good results. The two yoke plates 5.1, 5.2 extend essentially perpendicular to the longitudinal axis of the magnet armature 6. The excitation coil 4 is arranged between the two yoke plates 5.1, 5.2.

(15) The locking element 7 is formed in two parts and includes an activating part 7.1 and a locking part 7.2. The activating part 7.1 is preferably formed from a ferromagnetic material and is also part of the magnetic yoke. Furthermore, the activating part 7.1 is configured in the manner of a swivel armature and is pivotably connected to the lower yoke plate 5.2 of the magnetic yoke via a first joint 8, i.e. it is connected the yoke plate 5.2 facing away from the contact points. The locking part 7.2 is pivotably connected to the activating part 7.1 via a second joint 16. The locking part 7.2 is configured in the form of a slide. The locking part 7.2 extends approximately at right angles to the activating part 7.1. Depending on the position of the activating part 7.1, the locking part 7.2 therefore forms an angle of approximately 80 to 100, preferably approximately 85 to 95, with the activating part 7.1. The locking part 7.2 extends essentially parallel to the upper yoke plate 5.1 of the magnetic yoke, i.e. the yoke plate facing the contact points. The locking part 7.2 thus extends essentially at right angles to the direction of movement of the magnet armature 6.

(16) The locking part 7.2 may be guided on the upper yoke plate 5.1. Furthermore, the locking part 7.2 has a pin 19 extending in the longitudinal direction of the locking part 7.2. Starting from the end face of the locking part 7.2 facing away from the activating part 7.1, the pin 19 extends in the longitudinal direction of the locking part 7.2 in extension of the locking part 7.2. The upper yoke plate 5.1 has a groove (see FIG. 5) that extends essentially perpendicular to the direction of movement of the magnet armature 6 in the upper yoke plate 5.1. The pin 19 of the locking part 7.2 is guided in the groove 20 of the upper yoke plate 5.1. A pretensioning spring 9 is arranged between the pin 19 of the locking part 7.2 and the opposite end of the groove 20 in the upper yoke plate 5.1. One end of the pretensioning spring 9 is attached to the pin 19, the other end of the pretensioning spring is attached to the locking part 7.2. The locking part 7.2 is movable relative to the magnet armature 6 parallel to the yoke plates 5.1, 5.2.

(17) Furthermore, the locking part 7.2 has an elongated hole 21 that extends in the longitudinal direction of the locking part 7.2. The elongated hole 21 is clearly visible in FIG. 5. The magnet armature 6 has an anchor rod 6.1 that, starting from a part of the magnet armature 6 arranged in the excitation coil 4, extends upwards to the contact carrier 11. The anchor rod 6.1 of the magnet armature 6 is essentially cylindrical and passes through the elongated hole 21 of the locking part 7.2. In the region, in which the anchor rod 6.1 passes through the elongated hole 21 of the locking part 7.2, the anchor rod 6.1 has an annular groove 22. In the vicinity of the annular groove 22, the diameter of the anchor rod 6.1 is thus smaller than in portions of the anchor rod 6.1 above and below the locking part 7.2. The width of the annular groove 22 in the anchor rod 6.1 is slightly larger than the thickness of the locking part 7.2. The width of the elongated hole 21 in the locking part 7.2 is slightly larger than the diameter of the anchor rod 6.1 of the magnet armature 6 below the annular groove 21. The magnet armature 6 or the anchor rod 6.1 are therefore able to move up and down perpendicular to the locking part 7.2 through the elongated hole 21 in the locking part 7.2 when the locking part 7.2 is not engaged with the annular groove 22 in the anchor rod 6.1.

(18) In FIG. 4, the switching device 1 is shown in the locking position. Here, the activating part 7.1 is pivoted outward about the joint 8, i.e. away from the excitation coil 4, so that an air gap 23 is formed between the upper yoke plate 5.1 of the magnetic yoke and the upper end of the activating part 7.1. This air gap 23 forms the discontinuity of the magnetic yoke in the locking position. Thus, the locking part 7.2 is pulled outward, that is, to the right in FIG. 4, so that one end of the elongated hole 21 in the locking part 7.2 abuts the bottom of the annular groove 22 in the anchor rod 6.1 of the magnet armature 6. The locking part 7.2 thus engages in the annular groove 22 of the anchor rod 6.1 of the magnet armature 6 and locks the magnet armature 6 in the axial direction. The magnet armature 6 can thus be moved neither up nor down and the contact points of the switching device 1 are locked in the open position. In order to reliably hold the locking element 7, i.e. in particular the locking part 7.2, in the locking position when the actuation device is switched off, the pretensioning spring 9 is provided. As already described, the pretensioning spring 19 is inserted into the groove 20 in the upper yoke plate 5.1 of the magnetic yoke and is attached to the yoke plate 5.1 and to the locking part 7.2 and presses the locking part 7.2 into the locking position.

(19) FIG. 5 shows the second embodiment of the switching device 1 of FIG. 4 after unlocking the magnet armature with the magnet armature in the pulled position. In this position, the contact points of the switching device 1 are closed (ON position).

(20) For unlocking the magnet armature 6 the excitation coil 4 is energized. As a result, the activating part 7.1 of the locking element 7, which is designed as a swivel armature, is attracted by the two yoke plates 5.1, 5.2 due to the magnetic flux. The free upper end of the activating part 7.1 is moved towards the free end of the upper yoke plate 5.1 and the air gap 23, and thus also the magnetic yoke is closed. At the same time, the locking part 7.2 is also moved essentially perpendicular to the direction of movement of the magnet armature 6. The end of the elongated hole 21 of the locking part 7.2 is pushed out of the annular groove 22 of the anchor rod 6.1 of the magnet armature 6. The locking part 7.2 is now in an unlocking position. This releases or unlocks the magnet armature 6. The magnet armature or the anchor rod 6.1 can move up and down through the elongated hole 21 in the locking part 7.2.

(21) As described, the air gap 23 is closed at the same time. The activating part 7.1 thus then closes the magnetic yoke of the excitation coil 4. In this second embodiment, the magnetic yoke is formed by the two yoke plates 5.1, 5.2 and the locking element, or in particular the activating part 7.1 of the locking element 7. As a result, the magnetic flux acting on the magnet armature 6 is amplified and the magnet armature 6 is moved from the starting position to a pulled position against the force of a return spring not shown. As a result, the contact carrier 11 with the contact bridge 3 arranged thereon is moved in the direction of the stationary contacts 2 and the electrical contacts are closed.

LIST OF REFERENCE SIGNS

(22) 1 Switching device 2 Stationary contact 3 Contact bridge (movable contact) 4 Excitation coil 5 U-shaped section of the magnetic yoke 5.1 Upper yoke plate 5.2 Lower yoke plate 6 Magnet armature 6.1 Anchor rod 7 Locking element 7.1 Activating part 7.2 Locking part 8 Joint 9 Pretensioning spring 10 Nose 11 Contact carrier 12 Hook 13 Contact pressure spring 14 Bobbin 15 Hole 16 Second joint 17 Bolt 19 Pin 20 Groove 21 Elongated hole 22 Annular groove 23 Air gap