Patent Application
20150179382
The present invention relates to a control mechanism for a circuit-breaking device for low-voltage systems. The present invention also relates to a circuit-breaking device comprising said control mechanism.
It is common knowledge that low-voltage circuit-breaking devices (i.e. in applications with working voltages up to 1000V AC/1500V DC), such as automatic circuit-breakers, isolators and contactors, generally called “switching devices” and hereinafter simply called circuit-breakers, are devices designed to enable the proper operation of specific parts of electric systems and of the installed loads. Automatic circuit-breakers, for instance, ensure that the required rated current can flow towards the various users, enabling the loads to be reliably connected to and disconnected from the circuit, and enabling the automatic isolation of the circuit being protected from the electrical energy source.
It is also well known that circuit-breakers comprise a housing, one or more electric poles, each of which is associated with at least one pair of contacts suitable for coupling and uncoupling with one another. The circuit-breakers of the known state of the art also comprise a control mechanism that induces a relative movement of the pairs of contacts so that they can occupy at least one coupled position (when the circuit-breaker is closed) and at least one uncoupled position (when the circuit-breaker is open). The control mechanism conventionally takes effect on the moving contacts by means of a main shaft operatively connected to the moving contacts, or by means of a moving part that operatively supports said moving contacts. The control mechanism conventionally comprises a supporting frame that supports a kinematic chain with at least one element operatively connected to the moving part to enable the latter's displacement.
The control mechanisms usually comprise at least one tripping element that is enabled by a protection device in the event of an anomaly in the circuit in which the circuit-breaker is installed, e.g. a short circuit or an overload. A protection device, such as a thermal, thermomagnetic or electronic device, directly or indirectly enables the kinematic chain of the control mechanism in order to induce a rapid separation of the contacts and the consequent automatic opening of the circuit-breaker.
It is common knowledge that, during the working life of a circuit-breaker, virtually every component is subject to wear and tear, as a result of the considerable thermal and mechanical stresses to which it is normally liable for instance, and particularly during circuit-breaking manoeuvres or tripping due to short circuits. The functionality of the circuit-breaker depends, however, on the perfect efficiency of all of its parts, and particularly of the hinged joints that constitute the control mechanism. It is consequently necessary for these members to be suitably sized in order to guarantee an adequate working life of the appliance. In particular, the hinged joints that must guarantee a perfect functionality and efficiency in the long term.
The known control mechanisms have several drawbacks, above all in terms of their reliability. These controls comprise a relatively large number of mechanical elements, especially hinged joints that are crucial particularly in terms of weight and cost. In addition, they restrict the opportunities to install other mechanical parts in the vicinity if the latter's movements might intercept the pins forming part of the hinges. Moreover, fixing the pins to the corresponding supporting means during the assembly of the appliance normally entails the application of further retaining elements, such as elastic rings, split rings (Benzing or Seeger) or plugs, and more or less laborious and complex mechanical procedures.
The above-described technical demands have been translated into the custom of constructing relatively bulky controls containing a large number of components. These circumstances represent drawbacks that have a negative fallout on the global cost of manufacture and usage of the circuit-breakers. In a word, a contradiction has become apparent between the installation needs to increasingly miniaturise the circuit-breaker, reducing the number of components involved and the overall weight, and the need to increase or at least maintain its technical performance.
Based on these considerations, the principal aim of the present invention is to produce a control mechanism for a circuit-breaking device for use in low-voltage systems that enables the above-mentioned drawbacks to be overcome.
This aim is achieved by means of a control device according to the content of claim 1. Further advantageous features of the present invention are identified in the dependent claims.
The description that follows refers, exclusively for descriptive purposes, to a control mechanism installed in a single-switching multipolar circuit-breaking device for low-voltage systems. This is clearly on the understanding that the principles and technical solutions expounded in the description of the inventive concept also hold for other applications of the control mechanism, such as may be related to its use in double-switching circuit-breakers with a different number of poles.
Further characteristics and advantages will emerge more clearly from the description of a preferred, but not exclusive embodiment of the control mechanism according to the present invention, a non-limiting example of which is illustrated in the attached drawings, wherein:
figures from 13 to 15 are views of control mechanisms of the known state of the art.
The circuit-breaking device 1 comprises a control mechanism 30 according to the present invention that is operatively connected to said at least one moving contact to enable the latter's displacement between one position in which it is coupled with the corresponding fixed contact and at least one position in which it is uncoupled therefrom. The control mechanism 30 comprises a plurality of elements 31,32,33,34,35,36 at least a first element of which is pivotally connected to a second element by pin-shaped connection means.
The first and second elements preferably each comprise a pair of facing lateral portions that are connected by a transverse connecting portion. The pin-shaped connection means comprise a pair of pin-shaped ends, each of which emerges from one side of a lateral portion of the first element. The pin-shaped connection means also comprise a pair of seats, each of which is defined on a lateral portion of the second element. The pin-shaped ends are inserted in the seats so as to configure an axis of mutual rotation between the first and the second elements, and thereby enable the rotation of one of said elements in relation to the other.
The control mechanism 30 comprises elastic means operatively connected to the moving contact 20 to accelerate its coupling and uncoupling with the fixed contact 10. According to the invention, these elastic means are arranged so that they exert a retaining force on the pin-shaped ends sufficient to keep them coupled with the corresponding seats in which they are inserted. Said retaining force basically prevents the pin-shaped ends from emerging from their seats during the normal operation of the circuit-breaking device 1. This ensures the stability of the control mechanism's structure and thereby also its functionality.
According to a preferred embodiment of the invention, the elastic means are configured so as to exert a force on the pin-shaped ends such that the corresponding axis of mutual rotation maintains a substantially fixed position with respect to the corresponding seats, meaning by this that the elastic means come to bear in such a manner that the pin-shaped ends undergo no displacement with respect to their corresponding seats, and vice versa. Basically, the only allowable movement remains the mutual rotation of the two elements around their axis of mutual rotation, which occurs substantially in a fixed position with respect to a reference system integral with one of said elements.
The control mechanism 30 preferably also comprises retaining means configured so as to prevent the pin-shaped ends from emerging from their seats during the assembly of the control mechanism 30. In practice, said second retaining means serve the purpose of facilitating the assembly of the control mechanism 30 by keeping the pin-shaped ends inside their respective seats. The use of such retaining means enables the separate assembly of the control mechanism 30. This facilitates the process of assembly of the circuit-breaking device 1 in that the control mechanism 30 can be defined in advance and in an entirely independent manner.
The pin-shaped ends are preferably made in one piece with the lateral portions of the first element, for instance by means of a metal or plastic moulding process. According to a first possible embodiment, the pin-shaped ends are configured so as to emerge each on one internal side of one of the lateral portions of the first element so that they are facing each other. According to this embodiment, each of the pin-shaped ends emerges from a corresponding lateral portion in the direction of the opposite lateral portion. As explained in more detail later on, with this embodiment the first and the second elements are connected in such a manner that the lateral portions of the second element come to be located operatively in between the lateral portions of the first element.
According to an alternative embodiment to the one described above, the pin-shaped ends are configured so that they each emerge from an external side of one of the lateral portions of the first element. In this second embodiment, the two elements are connected so that the lateral portions of the first element come to be located operatively in between the lateral portions of the second element.
In the embodiment shown in the figures, the control mechanism 30 is operatively connected to the moving contacts 20 by means of the moving part 50. More precisely, the control mechanism 30 takes effect on the moving part 50 to determine its rotation around its longitudinal axis 400, which is translated into a displacement of the moving contacts 20. More precisely, the control mechanism 30 occupies a first operative configuration (hereinafter called the closed configuration) as a result of which each moving contact 20 is coupled with a corresponding fixed contact 10. The control mechanism 30 occupies a second configuration determined by a manual action on one of its operative elements (the manual opening configuration), as a result of which each moving contact 20 is separated from its corresponding fixed contact 10. The control mechanism 30 can also occupy a third configuration determined by the tripping of a protection device 135 due to the occurrence of a malfunction, such as a short circuit on the line in which the circuit-breaker 1 is installed.
With reference to the exploded view in
The elements of the control mechanism 30 are operatively connected so as to define at least one kinematic chain that takes effect on the moving contacts 20 by means of the moving part 50.
The control mechanism 30 comprises a supporting frame 31 consisting of a first pair of lateral supporting portions 41 connected by a first transverse connecting portion 21. The supporting frame 31 is basically the element that supports the kinematic chain in the mechanism and that maintains a substantially fixed position with respect to the housing 2 of the circuit-breaker during the operation of the control mechanism 30.
According to a preferred embodiment of the invention shown in
In detail, the supporting frame 31 comprises a pair of pin-shaped connecting ends 81 (see
With reference to
The first pin-shaped connection means comprise a first pair of pin-shaped ends 71 (hereinafter also indicated using the expression first pin-shaped ends 71) that each emerge from one of the lateral portions 42. More precisely, the first pin-shaped ends 71 are made in one piece with a corresponding lateral portion 42 emerging on the outer side of the external portion. The first pin-shaped connection means also comprise a first pair of seats 61 (hereinafter also indicated using the expression first seats 61), in each of which one of the first pin-shaped ends 71 of the main hook 32 is inserted. In particular, as shown in
In an alternative embodiment to the one shown in
With reference once again to
The control mechanism 30 shown in the figures comprises a third element 33 hereinafter indicated by the term “fork” 33. The structure of the fork 33 comprises a third pair of facing lateral portions 43 that are connected together by means of a third connecting portion 23. The fork 33 is operatively connected to the main hook 32 by means of second pin-shaped connection means that configure a second axis of mutual rotation 102 (see
The fork 33 is connected to a fourth operative element 34 in the control mechanism 30, hereinafter indicated using the term “control rod” 34, which comprises a fourth pair of lateral portions 44 transversely connected by a fourth transverse portion 24. The control rod 34 is operatively connected to the fork 33 by means of third pin-shaped connection means, which configure a third axis of mutual rotation 103 (see
The control rod 34 also comprises a second pair of connecting ends 82 made in one piece with the fourth lateral portions 44 so as to occupy mutually facing positions. Each of these second connecting ends 82 emerges from the internal side of a lateral portion and is inserted in corresponding operative seats (not shown) defined on the body of the moving part 50. More precisely, once said second connecting ends 82 have been inserted in the corresponding operative seats, they define an axis of mutual rotation for the control rod 34 in relation to the moving part 50, and vice versa. Said axis is located off-centre with respect to the axis of rotation of the moving part 50. As a result, the displacement of the control rod 34 determines the rotation of the moving part 50 and consequently of the moving contacts 20 contained therein.
The control mechanism 30 comprises a fifth operative element 35, hereinafter indicated using the term “lever-holder element 35”, which comprises a fifth pair of lateral portions 45 that are connected by a fifth transverse portion 25 at least partially folded into a U shape. Said fold serves the purpose of supporting a lever 35B extending from the housing 2 of the circuit-breaker 1 once it has been assembled. In practice, the lever 35B constitutes the interface between the control mechanism 30 and its operation from outside the mechanism, which may, for instance, be manual or servo-assisted. As explained in more detail later on, the lever 35B occupies a specific position depending on the operative configuration of the control mechanism 30 (closed, open or tripped). As a result, an operator can ascertain the operative status of the circuit-breaker 1 by observing the position of the lever 35B.
The lever-holder element 35 is operatively connected to the supporting frame 31 by fourth connection means comprising a fourth pair of pin-shaped ends 74 (hereinafter indicated with the term fourth pin-shaped ends 74) that are made in one piece with the supporting frame 31. The fourth connection means also comprise a fourth pair of seats 64 (hereinafter also indicated using the expression fourth seats 64), each of which is defined on one of the fifth lateral portions 45 of the lever-holder element 35. Once the fourth pin-shaped ends 74 have been inserted in the corresponding fourth seats 64, they define a fourth fixed axis of rotation 104 (see
As already mentioned above, the control mechanism 30 comprises a tripping element 36 that is operatively connected to the supporting frame 31 by fifth pin-shaped connection means according to the invention. More precisely, the tripping element 36 structurally consists of a sixth pair of facing lateral portions 46, which are connected by a fifth transverse connecting portion 26. The latter comprises a first hooked end 85 that serves the purpose of intercepting a second hooked end (not shown) of the main hook 32.
The fifth pin-shaped connection means comprise a fifth pair of pin-shaped ends 75 made in one piece with the sixth lateral portions 46 of the tripping element 36. More precisely, each of these fifth pin-shaped ends 75 emerges from an external side of one of the lateral portions 46. The fifth connection means also comprise a fifth pair of facing seats 65, each on one of the first lateral portions 41 of the supporting frame 31. Each of the fifth pin-shaped ends 75 is inserted in a corresponding fifth seat 65 so as to configure a fifth fixed axis of rotation 105 enabling the rotation of the tripping element 36.
With reference to the perspective view in
In the embodiment illustrated herein, the elastic means comprise a pair of control springs 37 operatively connected at one end to symmetrical portions of the fourth transverse portion 24 of the control rod 34, and at the other end to symmetrical portions of the fifth transverse portion 25 of the lever-holder element 35. In other words, the two control springs 37 lie parallel to one another and are connected to respective portions of the rod 34 and of the lever-holder element 35 by means of suitable hooks 37B. An elastic force comes to bear on the pin-shaped ends 71,72,73,74,74 of the coupled elements so that they maintain a stable position inside the corresponding seats 61,62,63,64,65 in which they are inserted. In other words, the control springs 37 come to bear on the various elements of the control mechanism 30 so as to keep each element constantly connected to the others. In practice, the control springs 37 exert a force on the various pin-shaped ends 71,72,73,74, with at least one component that is always concordant with the direction in which they were inserted in their corresponding seats 61,62,63,64,65. More precisely, whatever the configuration of the control mechanism 30, the control springs 37 always contribute to the generation of a positive action on the various pin-shaped ends 71,72,73,74,75 designed to keep them inserted in the corresponding seats 61,62,63,64,65.
In the control mechanism 30 the control springs 37 also serve the purpose of providing the mechanism itself with the elastic force needed to accelerate the rotation of the moving part 50, i.e. the opening or closing of the contacts, by means of the control rod 34. A further function of the springs 37 consists in ensuring the necessary pressure of the juxtaposed electric contacts when the circuit-breaker is in the closed position.
The above-described configuration of the elastic means is particularly advantageous in that it exploits the action of kinematic thrust elements (i.e. the control springs 37) to keep the control mechanism 30 stably assembled. This makes it possible, for instance, to widen the range of the tolerance relating to the dimensions of the pin-shaped ends and of the seats, with obvious advantages in terms of the overall manufacturing costs.
The passage from the closed configuration of
It is also clear that the above-described opening movement would not be possible if a traditional hinged joint, consisting of a continuous transverse pin supported by opposite portions of the mechanism, were used instead of the first pair of pin-shaped ends 71. In other words, any transverse pin coinciding with the axis 102 would not allow for the passage of the control springs 37, and the consequent displacement of the lever-holder element 35. From the above description, it is self-evident that eliminating the through pins enables movements that would otherwise be impossible.
The technical solutions adopted for the circuit-breaking device according to the invention fully enable the previously-stated technical aim to be satisfied. In particular, the use of pin-shaped connection means according to the above-described principles increases the reliability of the circuit-breaker, while also simplifying its construction. The circuit-breaking device thus conceived may undergo numerous modifications and variants, all coming within the scope of the inventive concept. Moreover, all the details may be substituted by others that are technically equivalent. In particular, the pairs of the pin-shaped ends and corresponding seats may be functionally exchanged without altering the inventive concept. Similarly, reversing the side from which each pin-shaped end emerges in relation to the corresponding lateral portion has no influence on the inventive concept.
In practice, any materials may be used, of any shape or size, according to need and the state of the art.
| Number | Date | Country | Kind |
|---|---|---|---|
| MI2009A000009 | Jan 2009 | IT | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13142704 | Jun 2011 | US |
| Child | 14525805 | US |
