EP1792326B1 - Bistable electromagnetic actuator with integrated lock - Google Patents

Abstract

The invention concerns an actuator comprising a fixed outer yoke (10), a mobile core (30) including a central shaft (39) extending along a longitudinal axis (X), a fixed field coil (20) surrounding the central cylinder (39) and a number N of fixed magnetic assemblies (23, 24) uniformly distributed about the longitudinal axis (X). Proximate to each end of the central cylinder (39), the core (30) comprises a number N of magnetic polar surfaces (33, 34) extending transversely to the axis (X). The core (30) is mobile in translation (T) along the axis (X) under the action of a current flowing through the coil (20) to drive mobile contacts of the switching device and the core (30) is mobile in rotation (R) by about 1/2N turn about the axis (X), without driving the mobile contacts.

Description

The present invention relates to an electromagnetic actuator usable in a switch electrical appliance, in particular of the circuit-breaker, disconnector and / or switch type, comprising a bistable control electromagnet for switching movable contacts of the appliance between an open position and a closed position. and comprising means for switching the apparatus into a triggered or engaged state. This type of actuator is suitable for use in low voltage or medium voltage equipment.

In such a switch device, there is usually an autonomous trigger mechanism, generally called lock, which is intended to open the contact poles and lock the movable contacts in the open position. This lock can be manually controlled or can be motorized depending on the destination of the device. It comprises for example a spring system which must be able to open the movable contacts in all cases, including when no current is present in the electromagnet or when the current flowing in the electromagnet is opposed to the movement opening. To overcome the effort of the electromagnet, so often requires an important device that is cumbersome and expensive, especially in a high-power installation where very significant mechanical forces are involved. mechanical means, such as spring systems, or a reserve of electrical energy stored elsewhere and usable for triggering the lock. In addition, mechanical or electronic devices are also needed to confirm the triggering order of the lock and to ensure the maintenance of the open triggered position. The EP0078324A which is considered to be the closest state of the art describes an electromagnetic actuator according to the preamble of claim 1.

The object of the invention is to provide a bistable electromagnetic actuator which internally integrates a trigger lock, thus avoiding the need for a separate lock. A switch device using this actuator would then have the enormous advantage of being lighter, less bulky and less expensive than a conventional device, for similar performance.

For this, the invention describes a bistable electromagnetic actuator for switch electrical apparatus, comprising a fixed outer yoke of ferromagnetic material, a movable core comprising a central shaft along a longitudinal axis, a fixed excitation coil surrounding the central shaft and a number N of sets fixed magnets evenly distributed about the longitudinal axis. In the vicinity of each end of the central shaft, the core has a number N of magnetic pole surfaces extending transversely to the longitudinal axis beyond the central shaft. The core is movable in translation along the longitudinal axis under the action of an electric current flowing in the coil for driving mobile contacts of the switch device, and the core is mechanically rotatable, preferably of approximate value. 1 / 2N turn around the longitudinal axis, without driving the moving contacts.

According to one characteristic, the N magnetic assemblies are composed of a number N of magnets fixed to the yoke and of a number N of flux concentrator elements made of ferromagnetic material placed between the N magnets and the N corresponding polar surfaces of the core. mobile. In the engaged state, each magnetic pole surface is substantially aligned along the longitudinal axis with each corresponding concentrator element.

According to another characteristic, the actuator further comprises return means for keeping the movable core in the open position in the triggered state.

According to another characteristic, the actuator comprises means for reducing the friction occurring during the rotational movement of the movable core, said friction reduction means comprising parts of non-magnetic material which also serve as an air gap for the core.

The invention also relates to an electrical switch device comprising a plurality of movable contacts cooperating with fixed contacts to switch an electrical load, and comprising such an electromagnetic actuator.

• la figure 1 représente une vue en coupe longitudinale BB d'un exemple simplifié d'un actionneur électromagnétique conforme à l'invention, dans une position fermée,
• la figure 2 représente la même vue en coupe de l'exemple de la figure 1, dans une position ouverte,
• les figures 3 et 4 montrent une vue en coupe transversale AA de l'actionneur de la figure 1, respectivement dans un état enclenché et un état déclenché,
• la figure 5 reprend la figure 3 en vue transversale de dessus,
• la figure 6 détaille un exemple simplifié d'un mécanisme de liaison entre le noyau mobile et des contacts mobiles de l'appareil.

Other features and advantages will appear in the detailed description which follows with reference to an embodiment given by way of example and represented by the appended drawings in which:

• the figure 1 is a longitudinal sectional view BB of a simplified example of an electromagnetic actuator according to the invention, in a closed position,
• the figure 2 represents the same sectional view of the example of the figure 1 , in an open position,
• the Figures 3 and 4 show a cross-sectional view AA of the actuator of the figure 1 , respectively in an engaged state and a triggered state,
• the figure 5 resumes figure 3 in transverse view from above,
• the figure 6 details a simplified example of a link mechanism between the mobile core and mobile contacts of the apparatus.

An electromagnetic actuator is used in a low voltage or medium voltage switchgear electrical apparatus. This actuator acts on movable contacts 58 for each power pole of the apparatus through a movable core 30. The actuator can assume a stable open position in which the movable contacts 58 are separated from corresponding fixed contacts 59 of the apparatus and a stable closed position in which the movable contacts 58 are pressed against the corresponding fixed contacts 59. The actuator also has a latched state that allows movement between these open and closed positions and a triggered state that keeps the moving and stationary contacts separate and that prohibits movement to the closed position.

With reference to the figures presented, the actuator is of the type comprising an outer yoke 10 and a fixed excitation coil 20 with a movable central core 30 and a number N of fixed magnetic elements. When the actuator is in the engaged state, the core 30 is movable in translation along a longitudinal axis X under the action of an electric control current flowing in the coil 20, so as to take the open position or the position closed.

The outer yoke 10 is made of ferromagnetic material (such as soft iron, mild steel or others). According to the preferred embodiment, it comprises a body 11 extending along a longitudinal axis X and extended by a number N of upper flanges 13 (see references 13a, 13b, 13c, 13d on the figure 5 ) at an upper end of the body 11 and the same number N of lower flanges 14 at the other lower end of the body 11. These flanges 13,14 are perpendicular to the central axis X, directed towards the axis X, regularly distributed around the X axis at each end of the body 11 and separated from each other by notches 17.

The movable core 30 is made of ferromagnetic material and comprises a central shaft 39 which extends along the longitudinal axis X and which is surrounded by the fixed coil 20. The shaft 39 is for example cylindrical. In the vicinity of its ends, it is extended by an upper plate 31 and a lower plate 32 fixed to the barrel 39. The plates 31, respectively 32, each have a number N of projections or branches in the form of radial pole teeth 33, respectively 34, which extend perpendicular to the X axis, deviating from the X axis beyond the central shaft 39 and regularly distributed around the axis X. Between the advances 33,34 of the plates 31,32 are a number N of indentations 37 whose periphery is closer to the X axis than the periphery of the 33,34 adjacent advances. The figure 3 thus shows an upper plate 31 notched with four advances 33a, 33b, 33c, 33d separated by four notches 37 between them. According to the invention, the advanced N 33, respectively 34, plates 31, 32 respectively, of the movable core 30 form as many magnetic polar surfaces 33, respectively 34, movable actuator whose role will be detailed below.

The actuator also comprises a number N of fixed magnetic assemblies which are regularly distributed around the X axis. Each magnetic assembly is preferably composed of a permanent magnet 23 bonded to a concentrator element 43 of magnetic flux. The actuator therefore has a number N of magnetic assemblies (composed of N magnets 23a, 23b, 23c, 23d and N concentrator elements 43a, 43b, 43c, 43d, see figure 4 ), identical to the number N of polar surfaces 33,34 existing on each plate 31,32 of the core 30 and the number N of flanges 13,14 at each end of the cylinder head 10.

The N magnets 23a, 23b, 23c, 23d are fixed against the inner wall of the body 11 of the cylinder head 10. They are for example of parallelepipedal shape to simplify their manufacture and can be positioned and maintained by various conventional means, such as parts plastic holding or wedging (not shown in the figures) and the shape arrangements of the inner wall of the cylinder head 10. The magnetization axes of the N magnets 23a, 23b, 23c, 23d lie in a plane perpendicular to the X axis and are indifferently either all directed to the X axis, or all directed away from the X axis.

The N concentrator elements 43a, 43b, 43c, 43d are made of ferromagnetic material and are fixed against the inner wall of the magnets 23a, 23b, 23c, 23d, between the magnets and the coil 20. In the embodiment shown, they have a parallelepiped shape and are also held in place by various conventional means of wedging. Each concentrator element 43 should preferably at least cover the whole of the inner wall of the corresponding magnet 23 and have a length along the upper X axis on each side to the length of the corresponding magnet, as shown in FIGS. Figures 1 & 2 . When the actuator is in the engaged state, the N concentrator elements 43 are substantially aligned along the X axis with the N polar surfaces 33,34 corresponding to the plates 31,32 of the core 30. In addition, the N concentrating elements 43 are substantially aligned along the X axis with the N upper flanges 13 and N corresponding lower flanges 14 of the yoke 10.

Thanks to these characteristics, these concentrating elements have the function of deflecting the magnetic flux lines B generated by the magnets 23a, 23b, 23c, 23d in a direction substantially parallel to the X axis in one direction or the other, in function of the position of the mobile core 30.

When the actuator is in the engaged state, the core 30 is movable in translation (arrow T) along the longitudinal axis X under the action of the coil 20 between the open and closed positions. The actuator is designed so that these two positions are stable and it is necessary to reverse the direction of the control current flowing in the coil 20 to move from one to the other position. Returning means, such as a return spring 50 placed between the movable core 30 and any fixed support of the apparatus (see figure 6 ), are also provided to facilitate a translational movement of the core 30, in the closed position to open position.

The actuator has drive means 51 in translation, which enable the movable core 30 to drive a movable slide 52, but only during its translational movement T. In the embodiment shown in FIG. figure 6 , the drive means 51 comprise a pivot connection 51 placed between the movable core 30 and the slider 52. This pivot connection 51 drives the slider 52 which itself drives a movable bridge 53 carrying the movable contact or 58 of each pole power of the device. A contact pressure spring 55 positioned between the movable bridge 53 and the slider 52 makes it possible to press the movable contacts 58 onto the corresponding fixed contacts 59 of the power pole in the closed position.

The actuator is designed so that, in the closed position (see figures 1 & 3 ), the upper ends of the concentrator elements 43a, 43b, 43c, 43d are opposite the polar surfaces 33a, 33b, 33c, 33d of the upper plate 31. Similarly, the polar surfaces 34 of the lower plate 32 are opposite lower flanges 14 of the cylinder head 10. A magnetic flux B coming from the magnets 23 can therefore flow in the actuator, by going along the following path: magnets 23, concentrating elements 43, polar surfaces 33 of the upper plate 31 of the core 30, barrel central 39, polar surfaces 34 of the lower plate 32, lower flanges 14 of the yoke 10, body 11 and magnets 23.

Conversely, when the actuator is in the open position (see figures 2 & 3 ), the pole surfaces 33a, 33b, 33c, 33d of the upper plate 31 are facing the upper flanges 13a, 13b, 13c, 13d of the yoke 10. Similarly, the lower ends of the concentrator elements 43a, 43b, 43c, 43d are next to the surfaces The magnetic flux B from the magnets then travels the following path: magnets 23, concentrator elements 43, polar surfaces 34 of the lower plate 32 of the core 30, central shaft 39, polar surfaces 33 of the plate upper 31, upper flanges 13 of the yoke 10, body 11 and magnets 23.

The stability of the two open and closed positions is thus ensured, even without the circulation of a coil current. To always keep a residual gap both in the open position and in the closed position, the actuator has one or more pieces 19 of non-magnetic material, such as bronze or plastic. These parts 19 have the form of plates or rings and are positioned for example against the inner face of the flanges 13, 14 (see Figures 1 & 2 ), but could also be positioned on the ends of the concentrator elements 43 or on the polar surfaces 33,34.

According to the invention, the core 30 is also rotatable (arrow R) about the longitudinal axis X under the action of a mechanical trigger device. This triggering device, not shown in the figures, can be indifferently manual or motorized depending on the type of switch device to which the actuator is intended. The rotational movement allows the actuator to move from an engaged state (indicated in figure 3 ) to a triggered state (indicated in figure 4 ). The amplitude of the rotational movement between the engaged state and the triggered state is preferably approximately 1 / 2N turn around the X axis. Conventional mechanical stops make it possible to limit the rotational stroke of the core 30 to the desired value. . The pivot connection 51 is designed so that the rotational movement of the core 30 does not alter the position of the slider 52 and therefore does not cause the movable contacts 58.

The polar magnetic surfaces 33, 34, formed by the advances of the plates 31, 32, have, in the engaged state, large magnetic contact surfaces S positioned either opposite the flanges 13 or 14 of the cylinder head 10 or facing the one or other of the ends of the concentrator elements 43, allowing the passage of the magnetic flux. Thus, the magnetic flux B generated by the magnets can circulate with minimum air gaps and create a magnetic holding force F which is proportional to the contact surfaces S and the square of the flow B. When a trigger device will cause a rotation of the mobile core 30, the pole surfaces 33,34 will no longer be aligned with the concentrator elements 43 or with the flanges 13,14, so that the contact surfaces S will decrease rapidly. The magnetic retention force F applied to the core 30 will thus also decrease rapidly.

After a rotation of about 1 / 2N turn (see figure 4 ), the actuator is in the triggered state. The polar surfaces 33a, 33b, 33c, 33d, 34 are now substantially opposite the notches 17 of the yoke 10 and therefore completely offset from the N concentrating elements 43a, 43b, 43c, 43d, N edges 13a, 13b, 13c, 13d and N edges 14, creating very important air gaps. Likewise, the flanges 13, 14 and the concentrator elements 43 are substantially aligned with the notches 37 of the core 30. The corresponding magnetic contact surfaces S are therefore eliminated and the magnetic retention force F applied to the core 30 is also practically zero. . It could also be envisaged that, depending on the dimensions chosen for the polar surfaces, the flanges and the concentrating elements, a rotation less than 1 / 2N turns is sufficient to reduce sufficiently the contact surfaces S, so as to make negligible the stress of hold F and thus get the triggered state.

The return force, generated by the return spring 50, is calculated to be less than the holding force F when the actuator is in an engaged state, which gives stable open and closed positions even in the absence In contrast, in the tripped state, the holding force F has practically disappeared and the only force applied in translation to the movable core 30 remains the restoring force exerted by the return spring 50 (FIG. Auxiliary increase of contact pressure springs 55), so that the movable core 30 is automatically translated in translation to the open position causing the opening of the movable contacts 58. The size of the spring 50 does not need to be very important to ensure this function, which contributes to the compactness of the device, because it has only a residual effort to fight in the triggered state.

If any electrical current flows in the coil 20, it can not cause an engine force likely to cause a translation of the core 30 as the triggered state will be maintained. Indeed, the gaps formed by the offset of the polar surfaces 33a, 33b, 33c, 33d, 34 are too important to circulate a significant magnetic flux in the core 30, thereby removing the contribution of the magnets 23. The triggered state therefore guarantees maintaining the open position and therefore the separation of the contacts as would a separate lock that would act on the mobile contacts autonomously.

The actuator is preferably provided with friction reduction means which appear during the rotational movement of the core 30. Advantageously, these friction reduction means may be composed in particular by the rings or plates 19 previously described to maintain residual air gaps in open and closed positions. These pieces 19 are therefore chosen in a non-magnetic material which also makes it possible to reduce the frictional forces of the moving core 30 during its rotational movements, such as bronze or teflon. The parts 19 may also comprise only such an anti-friction coating. Other additional means may be used to reduce the friction of the movable core (grooves in the frame of the coil, etc.).

The number N is at least equal to two to obtain in particular a good distribution of the forces in the mobile core 30. This then makes a rotation of about 1/4 turn around the X axis between the engaged state and the triggered state. In this case, the outer yoke 10 may be made of two identical and symmetrical parts with respect to X, each part having an approximate shape of C and comprising an upper rim 13, a body 11 and a lower rim 14, as suggested in FIG. figure 1 . The actuator then has a substantially parallelepipedal overall shape which is advantageously very compact and simple to produce.

In the embodiment presented Figures 3 to 5 the number N is equal to four and the movement of the rotating core is about 1/8 of a turn. In this case, the stroke of the rotational movement necessary to reach the triggered state is advantageously very short. The body 11 of the yoke 10 is then preferably cylindrical as shown in the figures. However, according to another variant, the body of the yoke may also have a polygonal structure having N facets in a transverse sectional plane.

An odd number N is also possible, as for example N equal to three. In this variant, all the different parts of the actuator three in number are then spaced about 120 ° between them around the axis X.

Consequently, the electromagnetic actuator described in the invention simultaneously performs the functions of closing and opening the power pole contacts by virtue of its translational movement between two stable positions and the triggering and interlocking functions of a lock. thanks to its rotational movement. It is robust enough to be used in low voltage or medium voltage devices. An electrical switch device comprising such an actuator will then have the distinction of being more compact, lighter, simpler to manufacture (less parts to assemble) and therefore more economical than a conventional device with a separate lock. Such an apparatus will also not require having a permanent energy reserve (with for example capacities), capable of separating the contacts movable in a safe way even if it is impossible to supply a control current in the coil.

It is understood that one can, without departing from the scope of the invention, imagine other variants and refinements of detail and even consider the use of equivalent means.

Claims (13)

1. Bistable electromagnetic actuator for electrical switch device, comprising a fixed external yoke (10), a moving core (30) comprising a central shaft (39) extending along a longitudinal axis (X), a fixed excitation coil (20) surrounding the central shaft (39):

   - the actuator comprises a number N of fixed magnetic assemblies (23, 43) evenly distributed about the longitudinal axis (X),

   - in the vicinity of each end of the central shaft (39), the core (30) comprises a number N of magnetic polar surfaces (33, 34) extending transversally to the longitudinal axis (X) beyond the central shaft (39),

   - the core (30) is mobile translation-wise (T) along the longitudinal axis (X) between an open position and a closed position under the action of an electric current circulating in the coil (20), to drive the moving contacts (58) of the switch device,
   characterized in that

   - the core (30) is mobile rotation-wise (R) about the longitudinal axis (X) between an engaged state and a tripped state, without driving the moving contacts (58).
2. Electromagnetic actuator according to Claim 1, characterized in that the core (30) is mobile rotation-wise (R) by a value roughly equal to 1/2N turns about the longitudinal axis (X).
3. Electromagnetic actuator according to Claim 1, characterized in that the N magnetic assemblies consist of a number N of magnets (23) fixed to the yoke (10) and a number N of flux concentrating elements (43) made of ferromagnetic material placed between the N magnets (23) and the N corresponding polar surfaces (33, 34) of the mobile core (30).
4. Electromagnetic actuator according to Claim 3, characterized in that, the external yoke (10) comprises a number N of top flanges (13) and a number N of bottom flanges (14), each top (13) and bottom (14) flange being substantially aligned along the longitudinal axis (X) with a corresponding concentrating element (43) of the mobile core (30).
5. Electromagnetic actuator according to Claim 3, characterized in that, in the engaged state, each magnetic polar surface (33, 34) of the mobile core (30) is substantially aligned along the longitudinal axis (X) with each corresponding concentrating element (43).
6. Electromagnetic actuator according to Claim 1, characterized in that the mobile core (30) comprises two plates (31, 32) fixed to the ends of the central shaft (39) and each offering a number N of overhangs (33, 34) to form the polar magnetic surfaces of the core (30) and a number N of notches (37) between each polar surface (33, 34) .
7. Electromagnetic actuator according to Claim 1, characterized in that the actuator also comprises return means (50) according to the translation movement, to maintain the mobile core (30) in the open position in the tripped state.
8. Electromagnetic actuator according to Claim 1, characterized in that the actuator comprises driving means (51) enabling the mobile core (30) to drive, translation-wise, a sliding piece (52) co-operating with the moving contacts (58).
9. Electromagnetic actuator according to Claim 1, characterized in that the actuator comprises friction-reducing means (19) that appear during the rotation movement of the mobile core (30), said friction-reducing means comprising parts (19) made of non-magnetic material also used as air gap for the core (30).
10. Electromagnetic actuator according to Claim 1, characterized in that the actuator comprises a number N of magnetic assemblies (23, 43) equal to two.
11. Electromagnetic actuator according to Claim 1, characterized in that the actuator comprises a number N of magnetic assemblies (23, 43) equal to four.
12. Electromagnetic actuator according to Claim 11, characterized in that the external yoke (10) and the central shaft (39) of the core (30) are substantially cylindrical in shape.
13. Electrical switch device comprising a number of moving contacts (58) co-operating with fixed contacts (59) to switch over an electrical load, characterized in that the switch device comprises an electromagnetic actuator according to one of the preceding claims.

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