EP1962319A2 - 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.

Here, the at least one first return spring is mounted between a stationary in the switching device arranged first support point and a magnet armature arranged second support point. These support points are offset laterally with respect to a system axis running parallel to the direction of movement of the magnet armature. The at least one first return spring is movably mounted with its second support point in a slotted guide on the armature.

The return spring is thus mounted stationary with respect to a housing or main body of the switching device with its first support point. With respect to this base body, the first return spring thus also retains its orientation, while the second support point slides along the magnet armature moving relative to the main body in the slide guide. In other words, the first return spring experiences only a change in length along its longitudinal direction, but no rotation or tilting with respect to the body.

The extension axis of the first return spring is in this case advantageously transversely to the system axis, ie the direction of movement of the armature with respect to the main body. For a parallel to the system axis extending portion of the slotted guide so that in the direction of the system axis force exerted on the armature force is zero.

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.

By using a slotted guide, in which the second support point of the at least one first return spring is mounted, a path-force curve is achieved, which depends on the path of the slide guide. The force of the spring is determined by the current angle of this path to the system axis. By changing this angle, the amount of that force component which acts on the armature in the direction of the system axis changes. Thus, a non-linear force curve can be realized by adjusting the angle. 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. It is therefore an optimal path-force curve realized that can be adapted to the appropriate application and can differ significantly from the previously known from the prior art path-force curves. By a slotted guide thus a particularly large variability in the design of the path-force characteristic is generated. Furthermore, a further fineness of the force-displacement curve can be achieved by the combination with other return springs and their corresponding dimensioning.

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

die Funktionsweise eines Ausführungsbeispiels einer Rückstellfederanordnung gemäß der Erfindung anhand von schematischen Prinzipdarstellungen,

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

the operation of an embodiment of a return spring arrangement according to the invention with reference to schematic schematic diagrams,

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 is a compression spring in the exemplary embodiment, is guided with its second support point 54 in a slide guide 70 which is rigidly connected to the magnet armature 6. In the example, the spring axis 62 is arranged transversely to the system axis 58 fixed in the housing of the switching device. The force exerted by the first return spring 50 total force F _{1ges, 0} now has a counter to the direction 56 of the closing movement directed to the system axis 58 parallel holding force F _{1p, 0} and a vertical to the path of the slide guide 70 component F _{1s, 0} . The relationship the total force F _{1ges, 0} exerted by the first restoring spring 50 in the direction of this spring axis 62 to the effective holding force F _{1p, 0} now depends on the actual angle β of the path of the guide link 70 relative to the system axis 58. For β = 45 ° F _1ges0 / F _{1p, 0} = 1. 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.

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.

Now moves the armature 6 under the action of the electromagnet 1 to this, so shifts with decreasing distance d guided in the slide guide 70 second support point 54 to a point at which the path of the slide guide 70 extends parallel to system axis 58 , Such an operating situation is in Fig. 6 shown. Then, the restoring force F _1p applied in a direction opposite to the direction of movement 56 by the first return spring 50 is zero. The course of the restoring force F _1p as a function of the distance d depends exclusively on the track shape of the link guide 70 relative to the system axis 58 and the spring constant and bias of the first return spring 50.

The course of the restoring forces is in Fig. 7 played. 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 proportion 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 illustrates the course of the force exerted by the first return spring 50 restoring force F _1p , depending on the shape of the slide guide 70 already disappears after a short distance traveled by the armature. The resulting total restoring force F is represented by the curve c. It can be seen from the figure that with the aid of the first return spring 50 a force curve can be achieved in which at least it is ensured that the restoring forces acting on the magnet armature during the closing movement do not increase, in the example even during the entire travel being smaller than the total holding force F ₀ are. The situation according to the prior art is represented by curve d.

In the in the 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 (5)

Electromagnetic switching device with an electromagnet (1) and a movable armature (6), and with at least one on the magnet armature (6) acting first return spring (50) on the armature (6) in an OPEN position, a non-zero holding force (F _{1p, 0} ), and which is mounted on the magnet armature (6) in such a way that the direction of the total force (F _1ges ) exerted on the magnet armature (6) depends on the position of the magnet armature (6) such that is opposite to the direction of movement of the closing movement of the magnet armature (6) acting component (F _1p ) of the total force (F _1ges ) in the OPEN position, wherein the at least one first return spring (50) between a stationary arranged in the switching device first support point (52) and one of the magnet armature (6) arranged second support point (54) is mounted, wherein first (52) and second support point (54) relative to a direction parallel to the direction of movement (56) of the magnet armature (6) System axis (58) are offset laterally to each other, such that the at least one first return spring (50) with its second support point (54) in a slotted guide (70) is movably mounted on the armature (6). Electromagnetic switching device according to claim 1, wherein the extension axis of the first return spring is transverse to the system axis. Electromagnetic switching device according to one of the preceding claims, wherein the first return spring (50) is a compression spring. Electromagnetic switching device according to one of the preceding claims, in which the component (F _1p ) of the total force (F _1ges ) exerted on the magnet armature (6) by the first return spring (50) is negative at at least one movement position of the magnet armature (6). Electromagnetic switching device according to one of the preceding claims, with at least one second return spring (8) whose spring axis (61) is oriented parallel to the direction of movement (56) of the magnet armature (6).

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