EP0585261B1 - Mechanism for an automatic switch - Google Patents

Abstract

The mechanism has a hand-operating toggle (1) fitted inside a casing (2) and spring-loaded in the off direction on which is articulated a lever (3, 4). During switch-on, a contact lever (5) pivoting about a spindle (2d) against the force of a spring (7) is supported on the lever. The contact lever (5) acts on a fixed contact (6) and can be clamped in the made position against the force of the spring (7). It is the purpose of the invention to simplify the supporting link between the lever (3, 4) and the contact lever (5) in order to obtain uniform release forces with only slight spreads within a production run of switches. To this end, between the hand-operating toggle (1) and the contact lever (5) is fitted a toggle lever consisting of a tension lever (3) and a bracket (4) which, in its stable position, is virtually tensioned and in which the form of the tension lever (3) causes its two articulated arms to assume a precisely defined top dead centre position. Thus during switch-on and in the on position, the toggle lever (3, 4) acts as a rigid lever. Only a substantially perpendicular load on its joint (3b/4a) applied via a release lever (9) towards dead centre causes the toggle lever (3, 4) to assume an unstable position under the effect of the contact lever's (5) return through the force of the spring (7). This releases the rigid connection between the hand-operating toggle (1) and the contact lever (5) so that the lever arm (5c) on the contact side can pivot into its breaking position. The mechanism of the invention is particularly suitable for fault-current protective switches and automatic cut-outs.

Description

The invention relates to a mechanism for a circuit breaker with the features of the preamble of claim 1.

Such a mechanism is known from DE-PS 500 098 for an electromagnetic overcurrent switch. The toggle lever mechanism described therein consists of several articulated brackets that press a spring-loaded contact lever against a fixed contact when the hand lever is switched on. The articulated brackets forming the toggle lever are mutually adjusted by means of a screw in order to precisely maintain the over-center position. In the area of the hinge axis, a curved surface is formed directly on a tab or attached as a separate part, on which a plunger of a release element acts. The curve of very differently curved shape should be approximately the same distance from the plunger during the switch-on movement, so that the plunger can push through the knee joint immediately after contact with an overcurrent. With this mechanism, the curve is very difficult to adapt to the movement sequence of the joint during the switch-on process and deviates considerably from the ideal condition depending on the contact wear and the different tolerances of the components. Therefore, a large actuation path of the plunger is required in order to cancel the over-dead center position of the knee joint lever and to interrupt the switch even under unfavorable conditions. With modern current-limiting circuit breakers with their short switch-off times, there are hardly any such long paths for the tripping devices. In addition, the trigger point is too imprecise. Another disadvantage is in the adjustment of the dead center position of the two articulated arms. In the case of mass production, as is customary with automatic switches, such an additional adjustment point can hardly be realized. In addition to the additional costs, the levers are much too large and heavy with an adjusting screw. To accelerate such a knee joint lever, the release forces must also be higher, which in turn would have stronger magnetic and thermal release elements.

Furthermore, a switching mechanism is known from DE 23 36 222 A1, in which a spring-mounted contact lever interacts with a manual control knob via several hinged tabs. One of these tabs holds a pin that is longitudinally guided in a slot, which in turn can be hooked behind a rotatably mounted pawl and thereby locks the entire mechanism. The double-armed contact lever is guided with a slot on a fixed axis and can be swiveled around it. On the side facing away from the contact point, a spring acts on the contact lever, which in the switched-on position tensions the entire mechanism and generates the contact pressure. This switching mechanism is disadvantageous in that several articulated arms are required, which are additionally locked with a latching mechanism. The achievement of low unlatching forces is achieved here only by a large component effort.

The invention has for its object to simplify the above-mentioned toggle lever mechanism and to improve it for a modern automatic switch, in particular a line and / or residual current circuit breaker, in such a way that the stable, almost extended over-center position of the toggle lever without Adjustment or setting work is given automatically and independently of the installation position of the switch, and the force and travel components required to release the latching are determined very precisely and can be maintained in series production with only slight scatter. At the same time, at every point of the switch-on movement, from the first touch of the contacts to the full, self-tightened switch-on position, a uniform and precisely defined trigger curve, which is always traceable regardless of the state of the contact point, should be achieved.

This object is achieved by a mechanism with the characterizing features of patent claim 1. Developments and advantageous embodiments of the invention are the subject of the dependent claims.

The mechanism according to the invention is advantageous in that the knee joint lever, in its almost extended, stable dead center position, acts practically like a rigid lever, and its two articulated arms only support one another without any additional parts. Due to the special design of the stretching lever and the round wire bracket in large-scale production, the over-center travel for all switches with small tolerances can be precisely maintained. All joint partners have a consistently high surface quality, so that only slight bearing friction occurs at the joint points and especially in the knee joint. In addition, the mechanism is hardly susceptible to vibrations and its pivot points are insensitive to dust or burn-off particles. The triggering force can also be precisely specified via the precise triggering path, because this is mainly determined by the stretching movement resulting from the over-dead center path up to the dead center position against the force of the contact lever spring. On the other hand, it is Influence of the tension spring buckling the two articulated arms in the direction of the over-center position due to their special arrangement in the switch-on position and thus also in the event of release.

A particular advantage of the invention is that during the switch-on process, a release cam of the extension lever and a shaft of the round wire bracket together describe a circular path which is precisely defined by the contact lever and is only flat. As a result, an exact, always constant tripping curve is defined, regardless of the state of the contact point and its changing erosion reserve when switching on, from the first contact touch to the fully self-locking switch-on position. Especially when it is switched on, it is triggered immediately and before the toggle end position is reached. It is also advantageous that the knee joint lever jumps into its unstable position only when the dead center position is exceeded, thereby releasing the contact lever for the switch-off movement, while if the trigger movement is insufficient, for example after a brief thermal load, it returns to the original stable over dead center position specified by the mechanism .

Fig. 1

zeigt den Mechanismus mit den für das Verständnis der Erfindung erforderlichen Bauteilen in Einschaltstellung, der in

Fig. 2

während des Auslösevorganges kurz nach Überschreitung des Totpunktes wiedergegeben ist. In

Fig. 3

ist die Ausschaltstellung des Mechanismus mit einschaltbereitem Handbedienungsknebel dargestellt. In jeweils größerem Maßstab zeigen

Fig. 4

die Übertotpunktlage des Kniegelenkhebels gemäß Fig. 1 schematisch,

Fig. 5

ein Bewegungsdiagramm des Kniegelenkhebels über der Auslösekurve während des Einschaltvorganges und

Fig. 6

in einer noch größeren Darstellung die Lagerung des Runddraht-Bügels im Streckhebel und seine Zuordnung zum Auslösenocken.

The invention is explained in more detail below on the basis of an exemplary embodiment shown in the drawing.

Fig. 1

shows the mechanism with the components required for understanding the invention in the on position, which in

Fig. 2

is reproduced shortly after the dead center is reached during the triggering process. In

Fig. 3

the switch-off position of the mechanism is shown with the ready-to-use manual control knob. Show on a larger scale

Fig. 4

the dead center position of the knee joint lever according to FIG. 1 schematically,

Fig. 5

a movement diagram of the knee lever over the trigger curve during the switch-on and

Fig. 6

in an even larger representation, the storage of the round wire bracket in the stretching lever and its assignment to the trip cam.

The mechanism shown in its functional level according to FIGS. 1 to 3 has a manual control knob 1 designed for manual switching, which for the most part is arranged within a housing 2 of the automatic switch, which is only indicated, and is pivotably mounted on an axis 2a fixed to the housing between fixed stops 2b, 2c. The hand control toggle protrudes approximately diametrically opposite its handle 1a protruding from the housing and has a bore 1b in which a stretching lever 3 is pivotably articulated by means of an axis 3a. Together with a U-shaped round wire bow 4 acting as a support lever, this forms a knee joint lever which will be described in more detail and which represents the essence of the invention.

The stretching lever 3 is a molded plastic part with a bearing bore 3b determining the joint for one leg 4a of the round wire bracket 4, the other leg 4b, which is supported on one side on a stop surface 3e, engages in a link 5a of a rigid contact lever 5. This is held approximately in the middle with an elongated hole 5b on a further housing-fixed axis 2d and pivotable about it, so that its contact-side lever arm 5c can be brought into the closed position with a fixed contact piece 6. A spring 7 which is suspended in the housing with an eyelet 7a and which has a hook 7b approximately between the link 5a and the elongated hole 5b on the contact lever 5 attacks, pulls this in the switched-on position (FIG. 1) against the bracket 4 of the knee joint lever located in its stable, almost extended over-center position together with the extension lever 3. The bracket shaft of the leg 4b supports the half-shell-shaped link 5a reliably and reliably, so that the spring 7 presses the contact lever 5, which is preferably designed as a flat part and is displaceable on the axis 2d, clockwise against the fixed contact piece 6 and generates the contact pressure.

Another, but considerably weaker tension spring 8 engages the stretching lever 3. This tension spring is suspended in a hook extension 3c and inside the housing in such a way that due to its direction of pull, particularly when switched off (FIG. 3), a pivoting moment is exerted clockwise and thus in the direction of the over-center position on the extension lever 3. 2 and 3, the lever arm predetermined by the line of action of the tension spring around the bearing point 1b / 3a of the extension lever is considerably larger than in FIG. 1, as is readily apparent from the figures. In contrast, in the switched-on position (Fig. 1) due to the choice of the points of application of the tension spring 8, its direction of action almost coincides with the connecting line of its suspension point (at 7a) in the housing and the axis 3a, so that the pivoting torque is almost "zero", and the release force is not affected. In this position, however, the tension spring 8 continues to load the manual control toggle 1 in the switch-off direction by exerting a clockwise torque on it about the axis 2a via the bearing point 1b, 3a of the extension lever.

On another axis 2e fixed to the housing is a the release lever 9 overlapping the contact lever 5, which can be pivoted clockwise in a known manner, for example in the case of a circuit breaker, by a thermal or magnetic release element (not shown). The release lever 9 has an area on the outer edge which is matched to the switching movements and the release behavior and has a release contour 9a and thus works on a specifically arranged release cam 3d of the extension lever 3 (FIG. 1, FIG. 5, FIG. 6).
This is in turn provided in the functional level of the mechanism below the semicircular trigger cam 3d with the aforementioned precise stop surface 3e, to which the bow shaft 4b 'of the round wire bow 4 bears on one side in the dead center position such that the bow shaft and release cam lie one behind the other in the axial direction and with the same curve provided are congruently arranged (Fig. 1 and 6). As a result, when they are switched on, they jointly describe a circular path with a large radius around the contact lever axis 2d. Especially this precisely fixed circular path of release cams 3d and bracket shaft 4b ', as it is shown in principle in Fig. 5 in its essential phases during the switch-on process by pivoting the manual control knob 1 from the position "0" to the position "I", simplifies the adjustment the release contour 9a of the release lever 9 considerably. The actual functionally important trigger contour 9a therefore also runs in a circular arc around the center of the contact lever axis 2d concentrically to the cam track, so that from the first contact (position "B") to complete switch-on (position "I") at any time and without delay under the same conditions Triggering can take place. Especially when it is switched on, the mechanism therefore unlatches immediately after touching the contacts 5c, 6 regardless of their condition and erosion.

From Fig. 5 it can also be seen that the articulation point 3b / 4a between the stretching lever 3 and the bracket 4 runs through a very unsteady curve during the switching-on process. Especially in the last phase of the switch-on movement, when the other joint 1b / 3a on the hand control toggle 1 swings over the connection line of axis 2a and shank shaft 4b 'indicated in a thin broken line, and the mechanism tenses itself, joint 3b / 4a of the knee joint lever runs from Maximum point back in a curve. In contrast to the almost linear circular path of the release cam 3d, this strongly curved curve at the articulation point 3b / 4a can only be reproduced with difficulty with a release lever and in any case requires a considerable free travel of the release member until the knee joint lever is pushed through.

The stop surface 3e, which is located below the unlatching cam and is particularly dimensionally matched to the two bearing points 3a, 3b, is also of significant importance, since in the almost stretched stable position of the knee joint lever formed from the extension lever 3 and bracket 4, the over-dead center path "X" is precisely specified (length of the Distance "X" in Fig. 4 schematically exaggerated). Depending on the spring forces and the lever arms of different lengths, this over-center travel determines the triggering behavior of the mechanism, so that a careful adjustment of the distance "X" will be necessary in accordance with the respective force relationships. Ultimately, however, the exact dimension in the large series can be closely tolerated, since in addition to the metallic axle parts to be precisely manufactured in diameter (axis 3a, bracket shafts 4a ', 4b'), only a molded part dimension of the extension lever 3 is received. All other dimensional deviations from the mechanism and housing parts, on the other hand, have practically no influence within the scope of customary manufacturing tolerances on this almost extended over-center position.

The knee joint lever, which acts as a rigid lever in the switched-on position (FIG. 1, FIG. 4), is also pivoted with its bearing axis 3a forming a second knee joint on the hand control knob 1 itself via dead center, based on the applicable connecting line (not shown) between the toggle axis 2a and the bracket shaft 4b 'engaging the contact lever. The entire mechanism is thus predominantly clamped in force in equilibrium via the spring 7, which is arranged approximately parallel to the stretching lever 3 and pulls approximately at right angles on the contact lever 5, the housing stop 2b and the fixed contact piece 6 forming the counter bearings. In contrast, the influence of the tension spring 8 is only of minor importance.

If the trigger lever 9 experiences a clockwise rotation in the switched-on position according to FIG. 1 - be it creeping through a thermal trigger or suddenly due to a magnetic trigger - its trigger contour 9a presses against the trigger cam 3d, and the stretching lever 3 describes a pivoting movement in a counterclockwise direction about its axis 3a. In the same sense, the bracket shaft 4a 'mounted in the stretching lever moves, while the bracket shaft 4b' supporting the contact lever 5 'is released from the stop surface 3e. Is the stretching lever finally pivoted so far on the release cam 3d that the knee joint forming shank 4a 'has traveled the distance "X" to the dead center position, the force acting on the release lever 9 due to the slightly stretching articulated arms must overcome the higher tension of the spring 7, the stable position is eliminated, and the knee joint lever jumps into its unstable position (FIG. 2). The entire tensioning of the mechanism is thus released and the contact lever 5 pivots about the axis 2d counterclockwise under the action of the spring 7 now providing the opening force. The lever arm 5c on the contact side lifts off the fixed contact piece 6 and reaches the switch-off position (FIG. 3).

If the hand control knob 1 is not held here, the tension spring 8 acting on the stretching lever 3 also pulls it into the position shown in FIG. 3 at about the same time, the hand control knob now coming to rest on the opposite stop 2c. Here, the axis 3a has moved on a circular path about the toggle axis 2a and thus the point of application of the tension spring 8 on the hook extension 3c to such an extent that a strong clockwise pivoting moment pulls the stretching lever 3 and thus the bracket 4 in the direction of the stable position. The in the scenery 5a of the contact lever with sufficient longitudinal play, but laterally guided bracket shaft 4b 'can only dodge to the extent that the extension lever with its abutment surface 3e in any case lies against the bracket shaft 4b' and the knee joint lever immediately returns to its almost extended Takes over dead center position (Fig. 3).

The mechanism is now ready to be switched on again. A corresponding, preferably manual, left-hand pivoting movement on the handle 1a then pushes the stretching lever 3, which also pivots on the axis 3a in the opposite sense together with the round wire bracket 4 as a practically rigid lever in the direction of the contact lever 5, which is pushed on its link 5a by the bracket shaft 4b 'finally reaches the switch-on position shown in FIG. 1; unless the trigger lever 9 already unlatches the mechanism during the switch-on movement, for example when it is switched on.

Claims (6)

1. Mechanism for an automatic switch, in which a contact lever (5), which is pivotable about an axle (2d) fast with the housing and during the switching-on operation bears against a toggle joint lever (3, 4), is bringable against the force of a spring (7) with its lever arm (5c) at the contact side into closed setting with a fixed contact member (6) by means of a manual operating knob (1) and the toggle joint lever (3, 4), which is articulated thereat to be pivotable and disposed in a stable position with almost straight over-dead-centre position of both its joint arms (3, 4), and braceable to be self-retaining in this setting, as well as with a trigger lever (9), which is separately borne to be pivotable and through which an about right-angled loading of the toggle joint in direction of the dead-centre position is caused by way of a trigger dog (3d) formed at one joint arm and the supporting effect of the toggle joint lever (3, 4) can be cancelled so that the contact lever (5) can pivot into the open setting by its lever arm (5c) at the contact side due to the force of the spring (7), characterised thereby, that the toggle joint lever, which is formed out of the straightening lever (3), which is borne at the manual operating lever (1), and a U-shaped round wire bracket (4), in its stable position retained by the spring (7) engaging at the contact lever (5) is disposed in an exactly defined over-dead-centre position solely by reason of an abutment surface (3e), which is arranged at the straightening lever (3) and matched with particular accuracy to both its bearing places (3a, 3b) and the round wire bracket (4), that the abutment surface (3e), which limits the over-dead-centre travel (x) of the toggle joint lever (3, 4) at the free bracket shank (4b′) at one end, is arranged in a plane parallel to the trigger dog (3d) and directly therebesides and that the roller-shaped trigger dog (3d) in the over-dead-centre position is arranged at the straightening lever (3) congruently in axial direction with that free limb (4b) of the round wire bracket (4), which acts on the contact lever (5), in such a manner that the trigger dog (3d) and the limb (4b) are guided together by the contact lever (5) about its axle (2d) on an exactly defined circular path of great radius during the switching-on operation and also during the manual switching-off at the manual operating knob (1) and the trigger lever (9) displays a circularly arcuate trigger outline (9a), which is arranged concentrically with this circular path about the same centre (axle 2d).
2. Mechanism according to claim 1, characterised thereby, that both the joint arms (3, 4) of the toggle joint lever are braced to bear each against the other in the almost straight stable position by a moment of a spring (tension spring 8) acting on them in the sense of their over-dead-centre position.
3. Mechanism according to claim 1 and 2, characterised thereby, that the straightening lever (3) borne at the manual operating knob (1) is drawn in the direction of the over-dead-centre position of the toggle joint lever (3, 4) by means of a tension spring (8) engaging tangentially at the manual operating knob (1) and at the same time loading it in switching-off direction.
4. Mechanism according to one of the claims 1 to 3, characterised thereby, that the abutment surface (3e) for the bracket shank (4b′) is shaped on at the straightening lever (3) together with the trigger dog (3d) between the latter and the contact lever (5) with reference to the functional plane of the automatic switch, wherein the trigger dog (3d) and the bracket shank (4b′) are arranged to lie one behind the other in axial direction with the same radial outline on the side of the trigger lever (9).
5. Mechanism according to one of the claims 1 to 4, characterised thereby, that the preferably rigid contact lever (5) is borne by an elongate hole (5b) on the axle (2d) fast with the housing and, in its lever arm lying opposite the contact place (5c, 6), displays a gate (5a), which matched to the wire diameter of the bracket (4) as well as to the switching movements, is guided within the limbs (4b) of the bracket (4), which engage at the contact lever (5), and is stabilised there against the force of the spring (7) with its bracket shank (4b′) lying thereagainst during the switching-on operation as well as in the switched-on setting.
6. Mechanism according to one of the claims 1 to 5, characterised thereby, that the stable position of both the joint arms (3, 4) is ended only after traversing the entire over-dead-centre travel (distance "X") in the hinge point (3b, 4a) due to a disengaging movement which is in a given case in slow motion and which is initiated by a thermal, magnetic or also another trigger organ of the automatic switch and transmitted from the trigger lever (9) to the trigger dog (3d) and the toggle joint lever under the influence of the opening contact lever (5) assumes its unstable position, whilst - in the case of an incomplete disengaging movement nearly to the dead centre - both the joint arms (3, 4) return into their original over-dead-centre position under the influence of the tension spring (8).

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