EP2030214B1 - Line circuit breaker and magnet yoke for a line circuit breaker - Google Patents

Abstract

In line circuit breakers with a combined overcurrent/short-circuit current tripping device, tripping should take place in a well defined manner in the case of an overcurrent and in the case of a short-circuit current. For this purpose, gaps (A, B) need to be set precisely. If the housing is made from a cost-effective housing material such as thermosetting plastic it is subject to shrinkage. As a result, the mentioned gaps may change. According to the invention, firstly an armature (24) is mounted in such a way that it changes its rest rotary position in the event of shrinkage of the housing. A magnet yoke (28) as part of the overcurrent/short-circuit current tripping device is mounted and shaped in such a way that the rotation is compensated for precisely, so that the mentioned gaps do not change despite the shrinkage.

Description

The invention relates to a circuit breaker, as in the document " US 3950 714 A discloses, according to the preamble of claim 6 and a magnetic yoke for a circuit breaker according to the preamble of claim 1.

The circuit breaker has a housing. In the housing, a switching device with a switch on and off switch and a combined overcurrent short-circuit current tripping device are arranged. Such a combined overcurrent short-circuit current trip device has been developed to use as few components as possible. It comprises, on the one hand, an armature and, on the other hand, a magnetic yoke, to which a bimetal element is attached, through which current flows when the switch is switched on. Further, a field line exit plate is arranged on the magnetic yoke, emerge at the outgoing from the bimetallic element in current flow and guided by the magnetic yoke magnetic field lines. The bimetallic element is arranged on a first side of the armature. In the undisturbed system, it bends in overcurrent and presses on the anchor. The field line exit plate is arranged on an opposite second side of the armature. At a short-circuit current, it magnetically attracts the armature. Thus, in both overcurrent and short-circuit current, the armature is rotated from a rest rotational position in the same predetermined direction. Upon rotation, it may cause the switch to turn off, for example, via a latch mechanism.

Cost-effective housing materials, such as thermosetting plastics (including urea compounds), are subject to a housing shortage over the life of the device. This is problematic because many components should be stored on the housing. The housing shrinkage then has the consequence that distances change the components to each other. This can have a negative effect on thermal tripping (overcurrent tripping) and magnetic tripping (short-circuit tripping).

The problem has often been solved by the fact that the entire switching mechanism was stored in metal, so that the housing fade could have no effect on the release. These constructions are very expensive.

Alternatively, low-shrinkage or shrinkage-free housing compositions, for example melamine compounds, were used. This solution is more expensive than the use of shrinkage-prone duoplastic materials.

It is an object of the invention to provide a cost-effective construction in which it is nevertheless ensured that the thermal and magnetic tripping takes place reliably.

The object is achieved by a circuit breaker with the features of claim 6 and by a magnetic yoke having the features of claim 1.

According to the invention, a housing is thus used which is subject to shrinkage and the armature is mounted in such a way that it changes its rest rotational position when the housing is weak. The magnetic yoke is mounted so that it also absorbs forces at a housing loss. It is shaped so that the absorbed forces cause a change in the position of the bimetallic element and the field line exit plate such that the change in the rest rotational position of the armature is counteracted. Preferably, this change is compensated (completely, as far as this is possible during a rotation).

The inherently disturbing shrinkage is thus deliberately not decoupled from the anchor, but instead the shrinkage is additionally exploited on the side of the magnetic yoke so that the shrinkage effect on the armature and the shrinkage effect on the magnetic yoke act exactly opposite.

Preferably, in the circuit breaker according to claim 6, an inventive magnetic yoke is used. Such a magnetic yoke for a circuit breaker has the property that a current-conducting bimetallic element can be fastened to it. It has a base body which is designed to guide magnetic field lines emanating from a bimetallic element attached to the magnetic yoke, when current flows, to a flat field line exit plate, through the surface normal of which a first direction is defined. On two opposite sides of the magnetic yoke bearing sections are defined with which the magnetic yoke is storable in a housing. The bearing portions further allow the introduction of forces from the housing into the magnetic yoke in a second and a third direction (which are generally substantially opposite one another). These directions are substantially perpendicular to the first direction, and by definition at an angle of 75 ° to 105 ° (preferably 85 ° to 95 °, particularly preferably 90 °) to the first direction.

The magnetic yoke according to the invention is characterized in that a flexible element is arranged between one of the two bearing sections and the main body, which deflects upon introduction of forces acting in the second and third direction and thereby enables a movement of the field line exit plate in a direction substantially the first direction is the same. By definition, it deviates from this direction by at most 20 ° (preferably by at most 10 °) (this deviation may be arbitrary from the direction of deviation).

In simple terms, it can be said that the magnetic yoke absorbs forces in one dimension and converts them in one movement into a dimension perpendicular thereto.

For this purpose, preferably, the bendable element is rod-shaped and has two rod positions with (compared to the other rod shape) reduced cross-section; which serve as predetermined bending points. By specifying the predetermined bending points, the type of bending is defined particularly clearly, so that the movement of the field line exit plate can be well-defined and the goal can be realized to counteract the change in the rest rotational position of the anchor very accurately.

In a preferred embodiment, the rod-shaped bendable element extends in a straight line at an angle of 35 ° to 55 ° (preferably 45 °) to the first direction on the one hand and to the second direction on the other hand from a bearing portion to the base body. In other words, the rod-shaped bendable element extends "obliquely". As a result, the forces acting in an optimal manner.

Preferably, one of the two bearing portions, between which and the base body, the bendable element is arranged, formed as a T-shaped foot. The foot allows on a first leg the engagement of a screw to define a position of the foot and thus of the yoke and on another (opposite) leg an abutment to hold the foot at different positions of the screw.

In a further preferred embodiment, the magnetic yoke is formed as a stamped and bent part. It is thus particularly inexpensive to produce.

FIG 1

schematisch einen Querschnitt durch einen erfindungsgemäßen Leitungsschutzschalter veranschaulicht,

FIG 2

eine perspektivische Darstellung der wichtigsten Schaltelemente des Leitungsschutzschalters aus FIG 1 veranschaulicht,

FIG 3

das bei dem Leitungsschutzschalter aus FIG 1 und FIG 2 verwendete Magnetjoch in Seitenansicht veranschaulicht,

FIG 4

das Magnetjoch aus FIG 3 in dem erfindungsgemäßen Leitungsschutzschalter von der Seite veranschaulicht, um so die Wirkungsweise des Magnetjochs zu erläutern.

Hereinafter, a preferred embodiment of the invention will be described with reference to the drawings, in which

FIG. 1

schematically illustrates a cross section through a circuit breaker according to the invention,

FIG. 2

a perspective view of the main switching elements of the circuit breaker FIG. 1 illustrates

FIG. 3

that at the circuit breaker off FIG. 1 and FIG. 2 used magnetic yoke in side view,

FIG. 4

the magnetic yoke FIG. 3 illustrated in the circuit breaker of the invention from the side, so as to explain the operation of the magnetic yoke.

An in FIG. 1 shown, designated as a whole with 8 circuit breaker comprises a housing 10 which consists of a material such as thermoset, which is subject to housing shrinkage. The actual switching device comprises a fixed contact 12 and a swiveling on the fixed contact 12 moving contact 14. The moving contact 14 is by means of a handle 16 in the in FIG. 1 spent switching position shown, wherein the handle 16 via a bracket 18 and a contact carrier 20 moves the moving contact 14.

On the contact carrier 20 engages a pawl 22, which engages in an anchor 24 in the ground state, ie, when the switch-on is to maintain, see in particular the illustration in FIG. 2 , If the armature 24 is pivoted clockwise, the pawl 22 is disengaged, and via the contact carrier 20, this causes a lifting of the moving contact 14 of the fixed contact 12 and thus an interruption of the on state.

Such rotation of the armature 24 can be initiated in two different ways. First, a bimetallic element 26 is provided, which is attached to a magnetic yoke 28. The attachment is particularly good in FIG. 4 to recognize. At rest, the bimetallic element 26 should have a distance A to the armature 24. The bimetallic element is traversed by current in the on state. When overcurrents, the bimetallic element heats up, bending. The bimetallic element 26 bends in this case to the armature 24, overcomes the distance A and ultimately presses on the armature 24 so that it moves in a clockwise direction. It is thus a mechanism for overcurrent tripping. simultaneously can be done with the help of the magnet yoke 28 even with short circuit currents tripping. For this purpose, a field line exit plate 30 is formed on the magnetic yoke 28, specifically on the other side of the armature 24 in comparison to the bimetallic element 26, in FIG FIG. 1 ie, to the left of the armature 24 instead of the bimetal element 26 to the right of the armature 24. In the initial position, a distance B between the field line exit plate 30 and the armature 24 is defined. In a short-circuit current, the bimetallic element 26 is traversed by a greatly increased current. The magnetic yoke 28 guides the magnetic field lines emanating from the current-carrying bimetallic element 26 to the field line exit plate 30, so that a magnetically attractive force is exerted by the field line exit plate 30 on the armature 24 and this is attracted. Even then he turns clockwise. It is thus a short-circuit release mechanism in addition to the thermal release mechanism. While in the thermal release mechanism, the bimetallic element 26 overcomes the distance A and then presses on the armature 24, the magnetic yoke 28 pulls the armature 24 from the opposite side in short circuit, so that the distance B is overcome, as well as a rotation of the same in the clockwise. The pawl 22 then latches out, and the electrical contact between the moving contact 14 and the fixed contact 12 is released, so the power interrupted.

In both types of triggering, it is important that the respective distance A or B is set precisely, so that the triggering is well-defined. To set the distances A and B is a locking screw 32, which engages in a T-shaped foot 34 of the magnetic yoke 28, more specifically in a leg 36 of the foot 34. The magnetic yoke is supported and held by the opposite leg 38 in a recess 40 in the housing. The position of the screw 32 is fixed. Upon rotation of the screw 32 thus does not change the position of the screw, but that of the magnetic yoke 28, in which the screw 32 engages. Accordingly, the distance A can be reduced and increased and at the same time the distance B are increased or decreased.

The shrinkage of the housing 10 with a longer housing life can now cause the distances A and B change, so that the triggering is no longer well-defined. The construction as shown in the FIG causes the fading to have opposite effects. The armature 24 is mounted in a bearing 41 on the housing 10. At a loss of the housing 10, the armature rotates clockwise, but not so far that the pawl 22 is triggered. In this case, the distance A is increased and the distance B is reduced. Structurally, it is now provided that the magnet yoke 28 exactly compensates for these changes in the distances A and B.

This in FIG. 3 The magnetic yoke shown as a whole has a main body 42 which has the function of guiding magnetic field lines. The magnetic field lines originating from the bimetallic element 26 are guided. For fastening the bimetallic element 26 is a fastening element 44 ( FIG. 4 ), for which there is space at an upper portion 46 of the magnetic yoke 28. The upper portion 46 functions as a storage section. As in FIG. 4 shown, the bearing portion 46 engages in a recess 48 in the housing 10 a. As an opposite bearing portion of the foot 34, which acts as mentioned above in the housing in the recess 40 acts.

Between the base body 42 and the foot 34, a bendable element 50 is arranged. The bendable element 50 consists of a rod 52 which tapers towards the foot 34 at a location 54 which simultaneously forms the lower leg of the T-shape of the foot 34. Towards the base body 42, the rod-shaped element 52 likewise tapers at a point 56 which is approximately at the height of the field line exit plate 30. The tapered points 54 and 56 serve as predetermined bending points. The entire rod 52 is substantially at an angle of α on the foot 34 and at an angle β on a surface normal 58 of the field line exit plate 30. α and β amount both about 45 °. This is made possible by the fact that the foot 34 is approximately perpendicular to the field line exit plate 30. If the housing fades, the forces F _shrinkage now act via the bearings 40 and 48 (see arrows in FIG FIG. 3 , also in FIG. 4 ) on the bearing sections 34 and 46, respectively. By the forces F _shrinkage , two directions of the force effect are defined which are approximately perpendicular to the surface normal 58. The actual angle slightly deviates from 90 °, but it moves in a range of 75 ° to 105 °.

By the forces F _shrinkage , the magnetic yoke 28 is now compressed. At the weakest points, this leads to a bending. These are the points 54 and 56. Thus, the rod-shaped element 52 kinks, in the image to the left, so that the base body 42 moves with the field line exit plate 30 corresponding to the arrow 60. The direction of movement according to the arrow 60 is almost equal to a direction predetermined by the surface normal 58. In any case, the direction of movement 60 does not deviate more than 20 ° from the direction predetermined by the surface normal 58.

The dimensions of the Magnetjochteile are selected in the yoke 28 so that the above-mentioned rotational movement of the armature, which is introduced via the bearing 40 of the housing 10 at its fading, is counteracted. As mentioned above, the armature 24 slightly rotates clockwise in case of fading, thereby increasing the distance A and decreasing the distance B. By the forces F _shrinkage simultaneously induced in the _shrinkage , the movement corresponding to the case 60 is caused. By the movement 60, the distance B is increased again. The dimensions should be such that the distance B again corresponds to the distance that is defined in the ground state. The movement 60 applies to the entire base body 42 and thus also to the upper part 46. Thus, the bimetallic element 26 also moves in the direction indicated by the arrow 60. Thus, the increase in the distance A is counteracted by the rotation of the armature 24 in the clockwise direction in case of shrinkage of the housing 10.

The construction therefore explicitly takes into account that the armature 24 moves due to shrinkage. The magnetic yoke 28 is designed so that this does not come into play, but that the housing shrinkage simultaneously causes a second effect (on the magnetic yoke 28), which counteracts the initial effect (on the armature 24). This counteracting effect is made possible in particular by the provision of the bendable rod-shaped element 52, in particular by the two predetermined bending points 54 and 56.

Claims (7)

1. Magnet yoke (28) for a line circuit breaker (8), on which a conductive bimetallic element (26) is arranged and which has a base body (42), which is designed to guide magnet field lines emerging from the bimetallic element (26) during the current flow to a field line outlet plate (30), by the surface normal (58) of which a first direction is defined and with mounting sections (34, 46) being defined on two opposite sides of the magnet yoke (28), with which the magnet yoke (28) can be supported in a housing (10) and which allows the introduction of forces (F _shrinkage ) from the housing (10) into the magnet yoke (28) in a second and third direction at a predetermined angle to the first direction in each instance,
   characterised in that
   a deformable element (52) is arranged between one of the two mounting sections (34, 46) and the base body (42), which element deforms with the introduction of forces (F _shrinkage ) acting in the second and third direction and as a result allows a movement of the field line outlet plate (30) in a direction (6), which essentially corresponds to the first direction.
2. Magnet yoke (28) according to claim 1,
   characterised in that
   the elastic element (52) is rod-shaped and has two points (54, 56) with a reduced cross-section which are used as desired flexion points.
3. Magnet yoke (28) according to claim 2, characterized in that the rod-shaped elastic element (52) extends linearly at an angle of (α, β) of 35° to 55° in respect of the first direction on the one hand and in respect of the second direction on the other hand from a mounting section (34) to the base body (42).
4. Magnet yoke according to one of the preceding claims,
   characterised in that
   one of the two mounting sections between which and the base body (42) the flexible element (52) is arranged, is embodied as a T-shaped foot (34) which at one limb (36) enables a screw (32) to engage in order to define a position of the foot (34) and thus of the magnet yoke (28) and at another limb (38) provides a counter bearing in order to hold the foot (34) in place in different positions of the screw (32).
5. Magnet yoke (28) according to one of the preceding claims, characterized in that it is embodied as a stamped bending part.
6. Line circuit breaker (8), with a housing (10), in which a switching device (12, 14, 16, 18, 20, 22) with a switch (12, 14) that can be switched on and off and a combined overcurrent short circuit current tripping device (24, 26, 28) are arranged, with the overcurrent short circuit current tripping device on the one hand including an armature (24) and on the other hand including a magnet yoke (28), on which a bimetallic element (26) is fastened, by means of which current flows when the switch is switched on, with a field line outlet plate (30) being arranged on the magnet yoke (28), on which field line outlet plate magnetic field lines emerging from the bimetallic element during current flow and guided by the magnet yoke (28) appear, with the bimetallic element (26) being arranged on one side of the armature (24) in order to press against the armature (24) during overcurrent and also with the field line outlet plate (30) being arranged on an opposite side of the armature (24) in order to magnetically attract the armature during short circuit current so that both during overcurrent and during short circuit current the armature (24) is rotated out of a rotational position at rest in the same predetermined direction, with the rotation potentially causing the switch to be switched off,
   characterised in that
   the housing (10) is subject to shrinkage and the armature (24) is mounted such that during the housing shrinkage, its rotational position at rest changes and the magnet yoke (28) is mounted (40, 48) such that it likewise receives forces (F _shrinkage ) during a housing shrinkage and that the magnet yoke (28) is moulded such that the received forces effect a change (60) in the position of the bimetallic element (26) and the field line outlet plate (30) such that the change in the rotational position at rest of the armature is counteracted and this is preferably balanced out.
7. Line circuit breaker (8) according to claim 6,
   characterised in that
   the magnet yoke is a magnet yoke (28) according to one of claims 1 to 5.

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