EP1430490A1 - Electromagnetic actuator - Google Patents

Abstract

The invention relates to a bistable electromagnetic actuator, in particular a drive for a vacuum interrupter chamber, comprising a yoke, at least one permanent magnet, at least one coil and at least one displaceable armature. A first magnetic flux is generated by the armature and the yoke in such a way that the armature is held in one position and the coil generates a second magnetic flux that actuates the armature. The permanent magnet is located between the yoke and a fixed magnetic return element, in such a way that the magnetic fluxes run via the magnetic return element. In addition, the armature outside the yoke at least partially covers a front face of the yoke, said face running perpendicularly to the direction of displacement of the armature.

Description

 ELECTROMAGNETIC ACTUATOR

description

The invention relates to an electromagnetic actuator, in particular an electromagnetic drive for a switching device, according to the preamble of claim 1.

Such electromagnetic drives are known, inter alia, from WO 95/07542. 1 shows, in principle, such a known electromagnetic drive 10, which has a circumferential yoke 11, which has two parallel longitudinal webs 12 and 13 and a respective cross web 14 and 15. Approximately in the middle, the longitudinal webs 12 and 13 have opposing pole shoes 16 and 17, to which permanent magnets 18 and 19 are attached. Between the permanent magnets 18 and 19 there is an armature 20 to which a rod 21 or 22 made of non-magnetic material is attached or fastened, each of which passes through an opening 23 and 24 in the transverse webs 14 and 15. Between the pole pieces 16 and 17 or the permanent magnets 18 and 19 and the cross piece 14 or the cross piece 15 there is a coil 25, 26. Depending on the excitation of the coil 25 or 26, the armature 20 can be shown in FIG. 1 Position are moved, the air gap 27, which has the dimension d, is minimized in this position. If the coil 25 is excited, then the armature is driven in the direction of arrow P until its end face facing the crossbar 14 abuts the inner surface of the crossbar 14.

In this way, a well-functioning bistable electromagnetic drive is formed for a switching device, in particular for vacuum circuit breakers. The measures taken to avoid eddy currents in both the yoke 11 and the armature 20 have already been taken into account in another patent application (German patent application 197 09 089.3).

In one embodiment, only the rod 21 is provided; the rod 22 is not required for an electromagnetic drive for a vacuum chamber and could at most serve to guide the armature 20.

The force with which the armature 20 is attracted to the lower or upper crosspiece depends on the effective area.

The object of the invention is to further improve an electromagnetic actuator of the type mentioned.

This object is achieved according to the invention by the features of claim 1.

The force with which the anchor or anchors are attracted to the yoke is also significantly increased by increasing the effective area.

How the arrangement for increasing the area can be made can be found in the subclaims.

The previous descriptions are based on a bistable design with two anchors, one on each of the two end faces of the yokes. In another embodiment, it is possible to build a monostable actuator with only one armature. The same coil is then used both for switching on and - in the opposite direction of the current - for switching off. The actuator is held in the off position by a spring when it is not switched on. , o 10108

The invention and further advantageous refinements and improvements of the invention are to be explained and described in more detail with reference to the drawing, in which some exemplary embodiments of the invention are shown.

Show it:

2 and 3 different embodiments of an electromagnetic drive,

4 shows a graphical representation of force profiles for a drive according to the prior art and a drive according to the invention,

5 to 9 further embodiments of the invention, with two anchors,

10 to 20 each an electromagnetic drive with an armature,

21 shows an electromagnetic drive according to the invention in accordance with a first embodiment with two armatures as a rectangular configuration of FIG. 9, FIG. 22 shows a perspective illustration of a cylindrical embodiment of FIG. 9, FIG. 23 shows an embodiment of an electromagnetic drive with two

Coils and different armatures and Fig. 24 the application of an electromagnetic according to the invention

Drive with an anchor for driving a vacuum interrupter.

Reference is now made to FIG. 2.

A drive 30 according to the invention has two elongated yoke parts 31 and 32 which are aligned parallel to one another. Approximately in the middle both yoke parts 31 and 32 have pole shoes 33 and 34, which point towards one another as projections; permanent magnets 35 and 36 are attached to the inner surface of the pole shoes 33 and 34. Between the permanent magnets 35 and 36 there is a yoke element 37 made of magnetic cal material, which is fixedly assigned to the two yoke parts 31 and 32. The yoke element 37 has a central bore 38, which is aligned parallel to the course of the yoke parts 31 and 32 and parallel to the course of the yoke element and sits there in the middle in the yoke element 37. The bore 38 is penetrated by a rod 39 made of non-magnetic material, to which the armature 40 and 41 are attached. The anchors 40 and 41 cover the adjacent end faces of the yoke parts 31 and 32.

Recesses 44 and 45 emanate from the end faces 42 and 43, which then step over into the pole shoes 33 and 34. The spaces 46 and 47 formed between the yoke element 37 and the recesses 44 and 45 serve to accommodate one coil 48 and 49, respectively.

2 shows the electromagnetic drive, in which the armature 41 bears against the end faces 43 a and 43 b of the yoke parts 31 and 32.

1, an air gap is only formed between the armature 20 and the lower or upper crosspiece 15, 14, in the present embodiment, an air gap 50 is obtained between the yoke element 37 and the armature 41 and an air gap 51 in each case and 52 between the end face 43 b or 43 a and the armature 41. This results in an increase in the attraction area and an increase in the attraction force of the magnet armature in the position shown in FIG. 2. If the coil 48 is now actuated, the armature 40 is attracted against the end faces 42 a and 42 b of the yoke and there are also three air gaps (without reference numbers): the air gaps between the armature 40 and the end faces 42 a and 42 b and the air gap between the armature 40 and the yoke element 37. The holding force is thus increased by a factor "(area at the air gap 50 + area at the air gap 51 + area at the air gap 52) divided by - area at the air gap 50", up to a maximum of 100 Because of their connection to the rod 39, both anchors 40 and 41 move at the same speed and are matched to one another in such a way that the distance between the anchors 40, 41 and the associated end faces on the yoke and on the yoke element alternately in both positions is. Of course, the distance between the armature 41 and the yoke parts 31 and 32 and the yoke element 37 could be different from the distance of the armature 40 from the yoke parts 31 and 32 and the yoke element 37, depending on the requirements.

If the air gaps 51, 50 and 52 assigned to the armature 41 are smaller in the tightened position than the air gaps assigned to the armature 40, then the holding force in this tightened position is greater than when the armature 40 has tightened. Such a design could e.g. B. may be necessary if the force required by the application is different in the on and off position.

3 shows a further embodiment of the invention. The drive 55 has two yoke parts 56 and 57 which, in addition to the recesses 44 and 45 (which should have the same reference number here to show the similarity), have further recesses 58 and 59 in which the armatures 40 and 41 are accommodated; one could also say that axially extending arms 60, 61 and 62, 63 are provided on the yoke parts 56 and 57, which cover the armatures 40 and 41 over their entire path of movement. As a result, in addition to the air gaps 51 and 52, an air gap 64 and 65 is formed between the outer peripheral surface of the armature 41 and the arms 62 and 63; Corresponding air gaps 66 and 67 are also between the arms 60 and 61 and the armature 40. This increases the force at greater distances between the armature 40 and the yoke parts 56 and 57, the distance d being able to be varied depending on the task and requirements.

4 shows a graphical representation of the tightening force F over the movement path W of the armature. The solid line L 1 shows the force-displacement curve of the embodiment according to FIG. 1. The tightening force is Fi for the armature in the position shown in FIG. 1 and F ₂ for the other position.

The dashed line L 2 shows the force-path curve for the embodiment according to FIG. 2. It can be seen that a force F _{2 is} measured in the respective tightened state, which is approximately twice as large as the force Ft; it crosses the line L 1 or L 2, what on it is to be attributed to the fact that the tightening force becomes smaller at a certain distance than the tightening force in the embodiment according to FIG. 1. The third line L ₃ lies above the line L ₂ in the positive or in the negative range; the tightening force F ₃ corresponds approximately to the tightening force F ₂ and, in contrast to the course of the line L 2, the tightening force does not drop as steeply as the tightening force according to the line L _2, which has the advantage of a higher work capacity. It can be seen that the two columns 64 and 65 or 66 and 67 contribute to an improvement in the force-displacement line.

The construction of the drive 70 (FIG. 5) differs from the drive according to FIG. 3. Here, the two yoke parts 31 and 32 are encompassed on both ends by a C-shaped body 71, 72, with the free ends facing one another the armature 71 and 72 each form an air gap 77, 78 and 79 and 80 with the associated outer surface of the two yoke parts 31, 32.

In the embodiment of the drive 81 according to FIG. 6, only U-shaped anchors 82 and 83 are provided with an otherwise identical structure, the inner surfaces of the legs 84, 85, 86 and 87 being able to interact with the yoke parts 31 and 32 in their entirety , which, if necessary, makes it possible to influence the tightening forces further than the arrangement according to FIG. 5.

FIG. 7 shows a variant of the arrangement of FIG. 3.

The drive 90 has two U-shaped armatures 91 and 92 which engage behind a recess 93 or 94 and 95 or 96 with arms 97, 98 or 99 or 100.

7 shows a variant of the arrangement according to FIG. 8. The yoke parts have recesses 101, 102 and 103 and 104. The associated anchors 105 and 106 are approximately U-shaped with legs 107, 108 and 109 and 110, which in the recesses 101, 102 and 103, 104 engage. In addition, the anchors 105, 106 have the legs 107, 108 and 109, 110 projecting projections 11, 112, 113 and 114, which with the associated end faces of the yoke parts 115 and 116 to form an air gap 117 and 118 between the armature 113th and the yoke parts 115, 116 and form the armature 111 and the corresponding end faces of the yoke parts 115 and 116.

9 shows a further embodiment of the invention with two anchors. The drive has the overall reference number 120 and comprises two yoke parts 121 and 122, which have an E-shape with legs 123 and 124 or 125 and 126 in the region of their free ends and in the middle in between each have a web 127 and 128 serving as a pole piece. The permanent magnets 129 and 130 are located on the inner surfaces of the webs 127 and 128. Coils 131 and 132 are arranged on both sides of the webs between the legs 123 and the webs 127 or 125 and 127 or 124 and 128 or 126 and 128. Between the two permanent magnets there is a yoke element 133 with a central bore 134 through which a rod 135 made of non-magnetic material extends. The free ends of the rods are firmly connected to T-shaped anchors 136 and 137; the longitudinal web 138 and 139 engages at least partially between the coils 131 and 132, the position of the free end of the longitudinal web 139 lying against the adjacent end face of the yoke element 133 in the position shown in FIG. 9, forming an air gap 140 therewith. The transverse webs 141 and 142 then each form an air gap 143 and 144 with the outer surfaces of the legs 125 and 126 or 145 and 146; in addition, between the free ends of the legs 125 and 126 and the longitudinal web 139 or between the free ends of the legs 123 and 124 and the longitudinal web 138 air gaps 147 and 148 and ^' respectively. 149 and 150 provided.

The drives described above always have two armatures with two coils. As another embodiment, drives with only one armature and one coil can be used, as shown below. This monostable arrangement has the advantages of reduced material consumption, small ^'design and a simpler structure. This contrasts with the disadvantages of the required switch-off spring, the additional holding force required to keep the switch-off spring tensioned in the on position, the required actuation of the coil in both current directions and the higher stress on the permanent magnet material due to demagnetization during switch-off. ö

With regard to the monostable drives, reference is made to FIG. 10. The drive 200 described here has two approximately U-shaped yoke parts 201 and 202. A coil 205 is inserted in the space 203 and 204 formed by the U-shape of the two yoke parts 201 and 202; the drive 200 also has a T-shaped armature which corresponds to the armature 136 and here bears the reference number 206. On a cross bar

207 a longitudinal web 208 is formed, which engages between the other legs 209 and 21.0 and partly in the coil 205. Permanent magnets 210 and 211 connect to the lower legs 201 and 202 in the drawing, at their free ends, and a yoke element 212 is provided between these two permanent magnets, also partially protruding into the coil. Several air gaps are thus provided: on the one hand between the transverse web 207 and the outer surfaces of the legs 209 and 210, then between the free ends of the legs 209 and 210 and the longitudinal web 208 and between the free front end of the longitudinal web

208 and the inference element.

The principle of this monostable actuator can be applied to all configurations according to FIGS. 2, 3 and 5 to 8.

11 shows a drive 220 with a U-shaped yoke 221. A permanent magnet 223 is attached to the inside of the crossbar 222, and a return element 224 is fastened to this permanent magnet 223, so that an E-shape is thereby formed with the Legs 225 and 226, the yoke element 224 together with the permanent magnet 223 being encompassed as a central leg by a coil 227.

For this purpose, an anchor 228 is provided, which is C-shaped, with between the mutually facing leg ends 229 of the C-shape and the outer surface of the leg 225 or 230 and 226 and between the free ends of the legs 225 and 226 and the yoke element 224 and an air gap is formed for each armature.

In the embodiment according to FIG. 12, the drive 231 has a U-shaped yoke 232, on the leg ends of which recesses 233 and 234 are provided; in this return y

An elongated flat armature 235 engages jumps, whereby an air gap is formed on the one hand between the outer peripheral surface of the armature 235 and the recess 233 and 234 and the broad side surface of the armature 235 and the steps 236 and 237 and the yoke element 224.

The same reference numbers are intended to indicate that the same functions are fulfilled here.

In the embodiment according to FIG. 13, the difference from that of FIG. 11 can be seen in the fact that the armature 240 is U-shaped and, with its legs 241 and 242, comprises the legs 225 and 226 of the yoke 222.

FIG. 14 shows a single-coil drive in which the yoke 250 is U-shaped, legs 251 and 252 being the same as the end faces or ends of the yokes 215 and 216 of FIG. 8; since the armature has the same shape as that of the drive according to FIG. 8, the armature shown in FIG. 14 has been given the same reference number 105.

15 corresponds to the embodiment according to FIG. 7, so that reference is made to the description there. The difference is that the yoke 260 with its legs 261 and 262 is U-shaped and the free leg ends have a recess 263 and 264 into which the armature 91 engages in the manner shown in FIG. 7.

The embodiments according to FIGS. 16 to 20, which lack a permanent magnet, essentially have a three-legged, E-shaped yoke, with a coil surrounding the inner leg; the anchor provided here is either U-shaped and engages in a recess on the outside; In the embodiment according to FIG. 19, two projections engage in an inner recess between the outer legs (see FIG. 14), and in the embodiment according to FIG. 18 the anchor is an elongated flat component. The perspective illustration according to FIG. 21 comes close to the embodiment according to FIG. 9; these are opposing yoke parts 121 and 122 with the coils 131 and 132 and the armatures 136 and 137; in between, as shown in FIG. 21, is the yoke element 133. Between the two armatures 136 and 137, the rod 135 made of non-magnetic material is arranged.

As can be seen from FIG. 22, the same or equivalent construction can also be such that the yoke, the armatures, the coils and the yoke element each form a circular cylindrical shape. It can be imagined that all the drives, which are shown in Figures 1 to 20, can also be cylindrical. The same also applies to the drives described below in accordance with FIGS. 23 and 24.

Reference is now made to FIG. 23. There is shown a two-armature and two-coil drive which is similar to the embodiment according to FIG. 9, the armature 137 according to FIG. 9 being replaced by an armature 270, so that the air gaps 271 and 272 between the adjacent legs 273 and 274 and the anchor 270 appropriate attention must be paid. The drive has the two E-shaped yoke parts 277 and 278; anchor 279 is T-shaped. The anchor 279 corresponds to the anchor 136.

The embodiment according to FIG. 24 shows the use of a drive with a coil 300 and two U-shaped yoke parts 301 and 302. Permanent magnets 307 and 308 are fastened to the free ends of the legs 304 and 306 and in between there is a yoke element 309 which is penetrated by a rod 310 in a central bore 311 and is connected in the region of the coil 300 with a T-shaped armature which bears the reference number 136 to show that the design is similar to the embodiment according to FIG the difference that only one coil is provided.

The rod 310 is connected via the spring element 311 to the movable contact stem 312 of a vacuum interrupter chamber 313, the free end of the rod 310 having an extension 314 which is caught in a collecting basket 315, see the extension 314 and the bottom 316 a spring 317 is arranged, which serves as a contact pressure spring.

The vacuum chamber is constructed in a manner known per se: it has a cylinder body 318 made of ceramic, which is covered at both ends by a cover! 319 and 320 is completed. The end of the contact stem 312 protruding into the cylinder 313 carries the movable contact piece 321 and between the cover 320 and the movable contact piece 323 a bellows 322 is arranged, which is connected on the one hand to the cover 320 and on the other hand to the contact piece 321 in a vacuum-tight manner. The cover 319 is vacuum-tightly penetrated by a fixed contact stem 323, on the free end of which the fixed contact piece 324 is attached. With 325 a power supply or discharge is designated; that which is connected to the movable contact stem 312 is not shown; it is formed, for example, by a movable copper cord.

Between the area of the yoke parts 301 and 302 and the collecting basket 315, the rod has a plate 326 fastened thereon; on this plate 326 engages one end of a compression spring 327, the other end of which is supported on a stationary plane. When the contact pieces 321 and 324 are to be brought into the switched-on position, the coil 300 is excited so that the armature 136 is drawn into the interior of the two yoke parts 301 and 302, in the direction of the arrow P. This compresses the spring 327 and accordingly stores energy , A certain contact force is applied to the contact pieces 321 and 324 via the contact pressure spring 317.

When the switch is to be turned off, coil 300 is energized in the reverse direction of current. This moves the armature in the opposite direction of the arrow P. This is supported by the spring 327, which is an energy storage spring.

24, a drive is provided which has only one coil. Of course, any drive can be provided, which is shown in Figures 1 to 23, that is also a drive with two coils.

Claims

claims 1. Bistable electromagnetic actuator, in particular drive for a vacuum interrupter, with a yoke, with at least one permanent magnet, with at least one coil, with at least one movable armature, so that a magnetic first flux is generated by the armature and the yoke, so that the Armature is held in position, the coil generates a second magnetic flux with which the armature is actuated, characterized in that the permanent magnet is arranged between the yoke and a fixed yoke element, so that the magnetic fluxes pass over the yoke element, and that the armature at least partially covers an end face of the yoke that is perpendicular to its direction of movement outside the yoke. 2. Actuator according to claim 1, characterized in that the yoke has two yoke bodies which each have a pole piece approximately in the center, which face one another and to which a permanent magnet is attached. 3. Actuator according to claim 1, characterized in that the yoke, armature, magnets are rectangular. 4. Actuator according to claim 1, characterized in that the yoke is cylindrical and has a strip of smaller diameter inside, on the inside of which an annular permanent magnet is fastened, and that both the yoke element are cylindrical. 5. Actuator according to one of the preceding claims, characterized in that the armature completely covers the end face of the yoke. 6. Actuator according to one of claims 1 to 4, characterized in that the yoke has a stepped recess in the region of its end face, fits into the armature. 7. Actuator according to claim 6, characterized in that the stepped recess is arranged on the inside of the yoke. 8. Actuator according to one of claims 1 to 6, characterized in that the armature comprises the end face and partially the outside of the yoke. 9. Actuator according to claim 8, characterized in that the armature has a C-shaped cross section, the mutually facing leg ends comprising the yoke on the outside thereof. 10: Actuator according to one of the preceding claims, characterized in that the armature is cup-shaped. 11. Actuator according to claim 10, characterized in that the armature carries a projection on the inside of the cup wall as a circumferential rib. 12. Actuator according to one of the preceding claims, characterized in that the armature engages in a recess on the outside of the yoke. 13. Actuator according to one of the preceding claims, characterized in that the armature has a projection in the center, with which it partially dips into the yoke. 14. Actuator according to one of the preceding claims, characterized in that two anchors located at opposite ends of the yoke are provided, which are connected to one another by means of a rod extending through the yoke element made of non-magnetic material. 15. Actuator according to one of the preceding claims, characterized in that only one armature and one coil are provided, that the magnetic yoke is O-shaped and the permanent magnet and the yoke element are fastened in the center between the legs on the yoke web, the permanent magnet being located between the yoke element and the yoke web, so that the actuator is monostable. 16. Actuator according to one of claims 1 to 13, characterized in that the yoke is E-shaped. 17. Actuator according to one of the preceding claims, characterized in that only 1 armature is provided, that the yoke is cup-shaped. 18. Actuator according to claim 17, characterized in that the permanent magnet and the yoke element is fastened to the bottom of the pot in the middle, the permanent magnet being located between the yoke element and the bottom of the pot. 19. Actuator according to one of the preceding claims, characterized in that a projection is formed on the bottom of the pot and carries the permanent magnet at its end, the projection simultaneously serving as a yoke element. 20. Actuator according to one of the preceding claims, characterized in that suitable measures are taken to avoid eddy currents, such as lamination, slitting or segmentation.