EP1962318B1 - Electromagnetic switching device - Google Patents

Abstract

The electromagnetic switching device comprises an electromagnet (1), mobile armature and reset spring (50). The total force of the armature is against the direction of the motion of the armature. A reset spring is stationary arranged in a supporting place (52) another reset spring is stored in the other supporting place (54). Both supporting place is kept parallel to the direction of the motion of the armature, running system axle is transferred laterally to each other. A reset spring with supporting place in a gear shift (70) is stored at the armature (6).

Description

The invention relates to an electromagnetic switching device with an electromagnet and a movable armature, which is mounted in the switching device with a force acting against the closing force and in an OPEN position different from zero holding force.

The basic operation of such an electromagnetic switching device is based on the Fig. 1 to 3 explained using the example of a contactor. According to Fig. 1 contains such a switching device, an electromagnet 1 with a magnetic yoke 2, on the example, two magnetic coils 4 are arranged for magnetic excitation. An armature 6 associated with the magnetic yoke 2 is resiliently mounted in a housing 10 of the switching device which is illustrated only symbolically by a return spring arrangement constructed from two return springs 8 connected in parallel. Magnetic yoke 2, solenoid 4 and armature 6 form an electromagnetic drive of the switching device. The armature 6 is non-positively connected via a prestressed contact spring 12 with a movable contact bridge 14. The movable contact bridge 14 are associated with two fixed contact carrier 16. The magnet armature 6 forms the actuator of the magnetic drive for the relative movement between the contact bridge 14 and the contact carrier sixteenth

The contact bridge 14 and the fixed contact carrier 16 are each provided with contact pieces or contacts 18. The switching contact formed by the movable contact bridge 14 and the fixed contact carrier 16 is in the open position (OPEN position). In this switched-off state, the contacts 18 are at a distance s ₀ and the pole faces 20 and 60 of the magnetic yoke 2 and the armature 6 are at a distance d = H. The return springs 8 are biased so that the armature 6 in the rest position of the OPEN position with a biasing or holding force F _{0 is} pressed against a stop 22.

When switching on the magnetic coils 4, the armature 6 is against the action of the force exerted by the return springs 8 holding force F = F ₀ in the direction of the magnetic yoke 2 in motion, as illustrated in the figure by the arrows.

Fig. 2 now shows a situation in which the contacts 18 touch the first time, the armature 6 has thus covered a distance s ₀ . At this time, the pole faces 20, 60 are at a distance d = d _s = Hs ₀ . The further closing movement of the armature 6 is now carried out against the force exerted by the return springs 8 increasing spring forces and in addition against the action of the force exerted by the parallel contact spring 12, also increasing spring force. Since the spring force exerted by the preloaded contact spring 12 is significantly greater than the spring force exerted by the return spring 8, the total restoring force acting on the armature 6 increases abruptly.

In the course of the force acting on the armature 6 magnetic force is greater than the force exerted by the return spring 8 and the contact spring 12 restoring force, and the armature 6 can continue to move in the direction of the magnetic yoke 2 until finally, as in Fig. 3 is shown, rests in an end or rest position with its pole faces 60 on the pole faces 20 of the magnetic yoke 2 (d = 0).

The associated force curve is in Fig. 4 applied. There, the force exerted on the armature 6 by the return springs 8 and the contact spring 12 restoring force F against the distance d between the pole faces 60, 20 of the armature 6 and the magnetic yoke 2 is applied. The curve shows that the return springs 8 (FIG. Fig. 1 ) in the OPEN position exert the holding force F ₀ . If current flows through the magnetic coils 4, the armature 6 moves under the action of the electromagnet In this movement increases with increasing length contraction of the return springs 8, the forces exerted on the magnet armature 6, oppositely directed restoring force F corresponding to the sum of the spring constant of the return springs 8 linearly to. At a distance d = d _S , the contacts 18 and the force acting on the armature 6 restoring force F increases by the connection of the biased contact spring 12 abruptly.

The holding force F ₀ exerted on the magnet armature 6 in the OPEN position secures the switching device in this position against accidental closing in the case of external mechanical vibration or impact load. Accordingly, during the entire distance traveled between d ₀ and d _S , the magnet armature 6 must always overcome the restoring force F exerted by the return springs 8, starting from a finite value required for mechanical securing of the magnet armature 6 in the OPEN position (holding force F ₀ ) increases successively. In order nevertheless to achieve short switching times (high closing forces), it is therefore necessary to design and dimension the magnet system 2, 4, 6 such that the magnetic force acting on the magnet armature 6 is significantly higher than the restoring force exerted by the return springs 8. A disadvantage is the constant increase in the restoring forces over the entire working range (magnetic lifting). This results in relatively large, unneeded forces that must be overcome by a correspondingly powerful designed magnetic drive.

From the DE 3340904 A1 a switching device is known which includes a return spring arrangement of two arranged in the manner of a two-armed knee lever lever compression springs. The switching device thus has a negative restoring force characteristic, that is, the force acting on the armature in the direction of its axis of displacement restoring force is reduced in the course of the closing operation of the switching arrangement.

The invention is based on the object to provide an electromagnetic switching device with improved spring force characteristic.

The above object is achieved according to the invention with an electromagnetic switching device having the features of claim 1. According to these features, the electromagnetic switching device includes at least a first, acting on the armature return spring, the non-zero holding force on the armature in an OPEN position exerts, and which is mounted on the armature such that the direction of the force exerted on the armature total force on the position of the armature such that the counter to the direction of movement of the closing movement of the armature acting component of the total force in the OPEN position is maximum. Furthermore, the switching device comprises at least a second return spring whose spring axis is oriented parallel to the direction of movement of the magnet armature.

By this measure, a path-force curve can be realized, in which a high holding force in the OPEN position is possible without the restoring force acting on the armature during the closing movement with decreasing distance from the electromagnet or increasing distance from the rest position in the OPEN position increases.

The first return spring is mounted on the housing or main body of the switching device with its first support point and the movable armature with its second support point each fixed but pivotally. During the movement of the armature along the system axis, the first return spring is pivoted, resulting in a change in the direction of the force exerted by this spring force on the armature. This also changes the amount of that component of force that acts on the armature in the direction of the system axis. Thus, a nonlinear force curve can be realized by the angle of the spring axis with respect to the system axis. It It is even possible that the force becomes negative at at least one movement position of the armature, that is, at least one position between the OPEN and CLOSED positions. In the OPEN position, a high holding force is exerted by the spring. During a closing operation of the switching device, the force direction of the return spring changes such that the force exerted on the armature in the direction of the system axis passes through a zero point and finally exerts a counterforce on the armature, which acts in the direction of the CLOSED position.

According to the invention, the first return spring is supplemented by the use of at least one further restoring spring whose spring axis is oriented parallel to the direction of movement of the magnet armature. This always exerts a force on the magnet armature in the direction of the OPEN position. By appropriate choice of the individual force curves and their superposition, therefore, an optimal path-force curve is realized, which can be adapted to the corresponding application and can differ significantly from the previously known from the prior art path-force curves.

Advantageous embodiments of the invention are given in the dependent claims.

Fig. 1-3

jeweils ein elektromagnetisches Schaltgerät gemäß dem Stand der Technik in einer Prinzipdarstellung zu verschiedenen Zeitpunkten des Einschaltvorganges,

Fig. 4

ein Diagramm, in die auf den Magnetanker des in Fig. 1-3 dargestellten Schaltgerätes von den Rückstellfedern und der Kontaktfeder ausgeübte Rückstellkraft in Abhängigkeit vom Abstand der Polflächen aufgetragen ist,

Fig. 5,6

ein Schaltgerät mit einer Rückstellfederanordnung gemäß einer ersten Ausführungsform der Erfindung in einer OFFEN-Stellung bzw. in einer Stellung während des Schaltvorganges jeweils in einem Prinzipbild,

Fig. 7

ein Diagramm, in dem die auf den Magnetanker ausgeübte Rückstellkraft gegen den Abstand von den Polflächen bei dem in Fig. 5,6 dargestellten Ausführungsbeispiel aufgetragen ist,

For further explanation of the invention reference is made to the drawing. Show it:

Fig. 1-3

in each case an electromagnetic switching device according to the prior art in a schematic representation at different times of the switch-on,

Fig. 4

a diagram pointing to the magnet armature of the in Fig. 1-3 shown switching device is applied by the return springs and the contact spring restoring force as a function of the distance of the pole faces,

Fig. 5.6

a switching device with a return spring arrangement according to a first embodiment of the invention in an OPEN position or in a position during the switching operation in each case in a schematic diagram,

Fig. 7

a diagram in which the force exerted on the armature restoring force against the distance from the pole faces at the in Fig. 5.6 illustrated embodiment is applied,

According to Fig. 5 is the magnetically mounted in a switching device, consisting of a soft magnetic material magnet armature 6 in the OPEN position on a stop 30, against which it is pressed by the action of at least a first return spring 50 and at least one second return spring 8.

The first return spring 50, which in the exemplary embodiment is a compression spring, is mounted with a first support point 52 in the housing of the switching device, i. fixed in the switching device. A first support point 52 and second support point 54 are laterally offset with respect to a system axis 58 running parallel to the direction 56 of the closing movement and are located transversely to this system axis 58 relative to a system axis 58 extending transverse axis from each other at a distance D.

The second return spring 8 corresponds structurally explained in the prior art return spring and is also designed in the embodiment as a compression spring whose spring axis 61 is oriented parallel to the direction of movement 56.

The force exerted by the first return spring 50 on the armature 6 total force F _{1ges, 0} has a counter to the direction 56 of the closing movement directed, parallel to the system axis 58 component - that is that of the first return spring 50 applied restoring or holding force F _{1p, 0} - and a perpendicular component F _{1s, 0} , which provides no contribution to the holding force. This perpendicular to the direction of movement 56 extending component F _{1s, 0} is compensated in a symmetrical arrangement when mirror-symmetrical to the system axis 58, a corresponding further first return spring 50 is arranged. The entire holding force F ₀ is composed of the holding force F _{1p, 0} exerted by the first return spring 50 and the holding force F ₂₀ exerted by the second return spring 8.

Under the influence of a force exerted by the only symbolically illustrated in the figure electromagnet 1 magnetic or closing force now moves the armature 6 against the action of the forces exerted by the first and second return spring 50, 8 restoring forces F _1p , F ₂ on the pole faces of the electromagnet 1 to. During this closing movement, the restoring force F ₂ exerted by the second return spring 8 increases linearly in accordance with the spring characteristic of the second return spring 8 with increasing reduction of the distance d between the armature 6 and the pole face of the electromagnet 1. During this closing movement, the total force F _1ges exerted by the first return spring 50 on the magnet _{armature also} increases. At the same time, however, their direction changes, since the angle α between spring axis 62 of first return spring 50 and system axis 58 increases steadily. By this change in direction exerted by the first return spring restoring force F _1p decreases. In order to enable such a change in direction, the first and second support points 52, 54 are mounted on the housing or on the magnet armature 6 so as to be pivotable at least to a limited extent.

In Fig. 6 is now a position shown in which the spring axis 62 of the first return spring 50 is oriented perpendicular to the system axis 58 (α = 90 °) so that the total force F exerted by the first return spring 50 _1ges perpendicular to the system axis 58 and perpendicular to the direction of movement 56 of the Magnetic armature 6 is directed. In this position exercises thus the first return spring 50 no restoring force counter to the further closing movement of the magnet armature 6 and F _1p = 0. In the course of the closing movement, the first return spring 50 introduces a spring force into the magnet armature 6 whose parallel to the direction of movement 56 or system axis 58 Component or restoring force F _{1 is directed} in the direction of movement 56 and thus contributes to an additional acceleration of the armature 6.

Which adjusting in this way the course of parallel to the system axis 58 oriented restoring forces F _1p of the first return spring 50 and F ₂ of the second return spring 8 and the sum of the open position until contact of the contacts is in Fig. 7 shown. The figure shows that the resulting at d = H holding force F ₀ from the holding force F _{1p, 0 of} the first return spring 50 and the holding force F _{20 of} the second return spring 8 composed. Curve a shows the course of the force exerted by the second return spring 8 restoring force F ₂ , which analogous to in Fig. 4 shown force profile with decreasing distance d increases linearly. Curve b shows the course of the force exerted by the second return spring 50, directed parallel to the system axis 58 restoring force F _1p , which in the embodiment starting from the OPEN position d = H decreases steadily and the distance d = d _{0 changes} the sign, ie in the Same direction acts as the force exerted by the electromagnet 1 magnetic force.

The sum F of the restoring forces F _1p , F ₂ exerted by the first return spring 50 and the second return spring 8 is shown in curve c. This curve shows that the sum force exerted by the two return springs 8, 50 acting in the direction of the system axis decreases non-linearly starting from a high holding force F ₀ . By comparison, in dashed line a situation is plotted as it results in the prior art, when the restoring force generated only by a biased second return spring 8 which exerts the same holding force F ₀ in the OPEN position.

At the in FIGS. 5 and 6 illustrated embodiments, a second return spring is arranged in addition to the first return spring, as it also finds use in switching devices in the prior art. Of the FIG. 7 However, it can be seen that the return spring has only the function to supplement the possibly with the first return spring too low holding power. The spring constant and the holding force of the second return spring can then be correspondingly reduced in accordance with the proportion of the total holding force available from the first return spring. In principle, it is also possible to install in the switching device only one or more first return springs, so that the armature can cover a major part of the switching path, without restoring forces acting on him.

In the exemplary embodiments, both first and second return springs are designed as compression springs. In principle, it is also possible to use tension springs instead of compression springs. In addition, by appropriate storage or slide guide of the first return spring (s) and return spring arrangements are possible in which second return springs are no longer required.

Claims (4)

1. Electromagnetic switching device with an electromagnet (1) and a movable magnet armature (6), and with at least one first resetting spring (50) acting on the magnet armature (6) which, in an OPEN position, exercises a holding force (F_1p,0) which is not zero on the magnet armature (6) and which is supported on the magnet armature (6) such that the direction of the overall force (F_1ges) exerted by it on the magnet armature (6) depends on the position of the magnet armature (6) such that the component (F_1p) of the overall force (F_1ges) acting against the direction of movement of the closing movement of the magnet armature (6) is at its maximum in the OPEN position, characterised by at least a second resetting spring (8), of which the spring axis (61) is oriented in parallel to the direction of movement (56) of the magnet armature (6) and which exerts a force on the magnet armature (6) acting against the direction of movement of the closing movement of the magnet armature (6) in the OPEN position.
2. Electromagnetic switching device according to claim 1, in which the at least one first resetting spring (50) is supported between a first support point (52) disposed at a fixed location in the switching device and a second support point (54) disposed at a fixed location on the magnet armature (6), wherein first (52) and second support point (54) are offset laterally to one another relative to a system axis (58) running in parallel to the direction of movement (56) of the magnet armature (6).
3. Electromagnetic switching device according to one of the preceding claims, in which the first resetting spring (50) is a compression spring.
4. Electromagnetic switching device according to one of the preceding claims, in which the component (F_1p) of the overall force (F_1ges) exerted on the magnet armature (6) by the first resetting spring (50) is negative at at least one position of movement of the magnet armature (6).

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