EP2743959B1 - Thermal trip device and current breaking apparatus comprising one such device - Google Patents

Description

TECHNICAL AREA

The present invention relates to thermal tripping devices for use in low-voltage electrical power cut-off devices in general, and in particular, electrical power cut-off devices installed at home and commonly called "branch circuit breakers".

STATE OF THE PRIOR ART

We know, for example from the document US 3,234,348 such an apparatus housed in an insulating casing and comprising at least one unipolar phase assembly and a control mechanism, said unipolar phase assembly comprising a breaking chamber accommodating a fixed contact and a movable contact, the different moving contacts of the different sets. being carried by a movable contact-carrying shaft, these movable contacts being able to be brought into an open position manually or automatically via, for each subset, a thermal protection device able to actuate the control mechanism of in order to open the contacts when an overcurrent occurs in the circuit to be protected, said thermal protection device comprising, on the one hand, an active bimetal capable of producing a heating when an overcurrent occurs above a certain level above the value of the nominal current, this heating leading to a thermal trip e of the control mechanism of the device so as to cause an opening of the contacts, on the other hand, a so-called compensation bimetal, intended to compensate for the variations that the changes in the ambient temperature determine in the circuit temperature, the bimetallic strip of compensation being mounted in rotation about a fixed axis first belonging to a support of the so-called first apparatus, the two bimetals being secured to one another at one of their ends by means of a hooking device, this hooking device being deactivated when the occurrence of an overcurrent, this deactivation causing actuation by the bimetallic compensation of the control mechanism in the direction of an opening of the contacts.

Such thermal trip devices are known in which the bimetallic bimetallic strip has a bent portion intended to allow it to be fixed by welding to a metal part, while preserving its length. This metal part has a crimped metal axis. This metal shaft is pivotally connected to a metal plate, the active bimetal being welded to this plate.
The rotation of the assembly comprising the bimetallic strip, the metal part and the seamed axis, this rotation being caused by the deactivation of the attachment device, makes it possible to obtain the thermal release of the device, this causing the opening contacts.
The aforementioned metal part further comprises an orifice for attaching a rod for resetting the assembly.
However, the presence of this bent part generates a certain inaccuracy on the deflection of this bimetallic compensation. On the other hand, this solution requires the realization of a weld, uses a large number of parts, and requires adjustments to make bimetallic parallel.
Other disadvantages include that thermal conduction occurs by the common axis and a direct thermal radiation of the active bimetal to the bimetallic compensation.

SUMMARY OF THE INVENTION

The present invention solves these drawbacks and proposes a thermal tripping device as well as a power cut-off device comprising such a device, this device implementing a reduced number of parts, eliminating the need to perform a weld, limiting the number of adjustments to be made, and considerably reducing the phenomena of thermal conduction and direct thermal radiation from the active bimetal to the bimetallic compensator.

For this purpose, the subject of the present invention is a thermal tripping device of the kind mentioned above, this device being characterized in that the compensation bimetal is fixedly mounted at least partly in a recess provided in an insulating electrical support part, said support being arranged with respect to the active bimetal in such a way that it forms a screen capable of protecting the bimetallic compensating of the thermal radiation generated by the active bimetal.
Thanks to these characteristics, the thermal radiation emitted by the active bimetal is stopped and is not transmitted to the bimetallic compensator.

According to a particular characteristic, the aforementioned bimetallic strip is plugged at least partly into said part.
Thanks to these characteristics, it is no longer necessary to perform a weld and the bent portion intended to allow this weld bimetallic compensation on a metal part is no longer necessary. The imprecision on the deflection generated by the bent portion is removed, and the settings to make the bimetallic parallel are removed.

According to another feature, the aforementioned housing comprises a space capable of allowing limited deflection of the bimetallic strip.
Thus, beyond a certain ambient temperature value, there is no longer any thermal compensation, which makes it possible to avoid thermal runaway.

According to another feature, the aforementioned support piece is made of plastic.

According to another characteristic, this support part comprises, in the vicinity of one of said first ends, a bearing portion adapted to be pivotally mounted about the axis of rotation of the compensation bimetallic strip, said axis being fixed to a fixed support of the device.

Thus, the pivot connection is made between this part and the axis of rotation, which avoids the crimping of an axis.
In addition, this bearing portion prevents heat transmission between the two bimetals.

According to another characteristic, the active bimetal is fixed by a said one of its ends, located opposite the so-called first end of the support part, to the aforementioned fixed support of the device, the bearing part allowing to avoid the thermal conduction between the active bimetallic and the bimetallic compensating via the axis of rotation of the bimetallic compensating.

Another subject of the present invention is a current-breaking device comprising a thermal tripping device comprising the aforementioned characteristics taken alone or in combination.

According to a particular characteristic, this apparatus is characterized in that this support part cooperates with a resetting device able to recall the hooking device in the activated position after the opening of the contacts following the occurrence of an overcurrent.

According to another characteristic, the so-called second axis of rotation of the movable contact-carrier shaft and the so-called first axis of rotation of the compensating bimetallic strip are brought close to one another and extend substantially in parallel. one in relation to the other, and in that the movable contact-carrying shaft comprises a so-called first piece cooperating with a so-called second piece integral in rotation with the compensating bimetallic strip, these two parts being arranged relative to one another to the other such that after triggering of the mechanism, during driving of the movable contact shaft in the direction of the opening of the contacts, the so-called first part rotates the so-called second piece and therefore the bimetallic compensating in a direction opposite to that having triggered the mechanism, until the re-latching of the two bimetallines relative to each other.

According to another characteristic, this apparatus comprises biasing means of the bimetallic strip to a trigger position of the control mechanism.

According to another characteristic, these return means comprise a spring bearing by one of its ends, on the so-called first support of the axis of rotation of the bimetallic strip, and by its opposite end, on the insulating support housing the bimetallic compensation.

According to another characteristic, this apparatus is a branch circuit breaker.

BRIEF DESCRIPTION OF THE FIGURES

• La figure 1 est une vue en perspective, illustrant une platine supportant les différents éléments d'un appareil de coupure du courant selon l'invention,
• La figure 2 est une vue en perspective correspondant à la figure 1, avant le montage des pièces de confinement de la coupure sur la platine,
• Les figures 3 à 7 sont des vues en perspective selon des orientations différentes, illustrant un bilame de compensation monté dans une pièce formant support selon l'invention,
• Les figures 8 et 9 illustrent une pièce formant support seule, respectivement selon deux orientations différentes,
• La figure 10 illustre un ensemble comportant le support des bilames destiné à être fixé sur une platine appartenant à un appareil selon l'invention,
• Les figures 11 et 12 sont deux vues partielles en perspective, illustrant selon deux orientations différentes, l'arbre porte-contacts mobiles et le dispositif de protection thermique, ainsi que le dispositif de réarmement du bilame de compensation, selon l'invention,
• Les figures 13,14 et 15 sont des vues partielles en perspective, illustrant ces éléments respectivement pour les trois figures, dans une position fermée non déclenchée du mécanisme, dans une position fermée déclenchée du mécanisme et en position ouverte réarmée du mécanisme.

But other advantages and features of the invention will become more apparent in the detailed description which follows and refers to the accompanying drawings given solely by way of example and in which:

• The figure 1 is a perspective view, illustrating a plate supporting the various elements of a current-breaking device according to the invention,
• The figure 2 is a perspective view corresponding to the figure 1 , before mounting the containment parts of the cut on the plate,
• The Figures 3 to 7 are perspective views in different orientations, illustrating a bimetallic strip mounted in a support part according to the invention,
• The Figures 8 and 9 illustrate a single support piece, respectively in two different orientations,
• The figure 10 illustrates an assembly comprising the bimetallic support intended to be fixed on a plate belonging to an apparatus according to the invention,
• The Figures 11 and 12 are two partial views in perspective, illustrating in two different orientations, the movable contact-carrying shaft and the thermal protection device, and the resetting device of the bimetallic strip, according to the invention,
• The Figures 13.14 and 15 are partial perspective views, illustrating these elements respectively for the three figures, in a closed position not triggered mechanism, in a closed position triggered the mechanism and reset open position of the mechanism.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

On the figure 1 has been shown a plate P on which are mounted the various elements of an electrical protection device such as a branch circuit breaker allowing an individual to be connected to the electrical network, said circuit breaker being intended to be located between a meter and a table electric. This assembly is intended to be mounted in an insulating housing (not shown), this housing having an opening for the passage of a lever M for the operation of the apparatus and having access openings to input terminals and to output terminals intended to be electrically connected respectively to the meter and to the electrical panel.

This device is of the multipole type and mainly comprises a control mechanism 1 and, according to this particular embodiment, four unipolar assemblies 2, 3, 4, 5 comprising three assemblies 2, 3, 4 intended to cut a phase and an assembly. unipolar 5 for the neutral cut, each of these sets being associated an input terminal and an output terminal. Each unipolar assembly 2, 3, 4, 5 comprises a fixed contact 6 electrically connected by a flexible conductor to one of the terminals, and a movable contact 7 electrically connected by a flexible conductor to the other of the terminals.

This movable contact 7 is supported by a movable contact holder shaft 8 common to all the unipolar assemblies, and adapted to be rotated by a control mechanism 1 between a position in which the fixed and movable contacts 6 and 7 are open. position in which the fixed and mobile contacts are closed.

The control of the opening of the contacts can be effected either manually by the operation of a lever M belonging to the control mechanism 1, or automatically by means of a protective device comprising a magnetic protection device 9 against instantaneous overloads of electric current, and a thermal protection device 10 against prolonged overloads of electric current.

Thus, each unipolar phase assembly 2,3,4 comprises an electric circuit comprising, mounted in series with the fixed contacts 6 and mobile 7, a thermal protection device 10 and a magnetic protection device 9. These two protection devices 9 Each comprise an actuator adapted to act on a so-called transfer rod 11, said bar extending substantially parallel to the alignment direction of the unipolar assemblies 2, 3, 4 and being intended to transmit the trigger or release command. opening of the contacts to the control mechanism 1, which acts to drive the shaft 8 movable contact carrier in an open position of the contacts 6,7 of all unipolar assemblies.

This apparatus also comprises a differential protection device comprising a differential relay 38 capable of sending an opening command to the control mechanism 1 during an imbalance caused by a receiver having a fault current, this device not being related with the invention will not be described in more detail.

As this is more particularly illustrated on the figure 2 each unipolar subset of said phase 2,3,4 further comprises a so-called containment piece of the cut-off 17, more commonly known as "capoule", which is intended to be fixed on the plate P and comprises a recess 21 of substantially parallelepipedal shape closed at its lower part by the plate P. This recess 21 forms a breaking chamber intended to accommodate an arc extinguishing chamber 22, a fixed contact 6 and a movable contact 7.

As more particularly illustrated on the figure 2 according to this particular embodiment of the invention, the confinement part 17 supports on the one hand the coil 25 of the magnetic protection device 9, which is soldered on a shunt 39 described in the following and on the other hand, the bimetallic strips of the thermal protection device 10, which comprise an active bimetallic strip 26 and a so-called bimetallic bimetallic strip 27 whose function will be described in the following.

Thus, this apparatus also comprises a nominal current calibration shunt 39 which it is desired to define for the apparatus in question, this shunt being screwed on the distributor and being connected by one of its ends to the coil 25 magnetic protection device.

It will be noted that the shunt is in parallel with the coil and the bimetal, the coil and the bimetal being in series or in parallel with each other.

In operation, this apparatus is connected by connecting the respective mechanisms of the different assemblies to the corresponding phases and to the neutral of the power supply network, by means of the input connectors, while the user's installation to be protected is connected. to the output connectors. Functionally, the thermal protection device 10 serves to signal lower overcurrents, for example up to ten times the rated current established for the device, while the coil 25 is responsible for reporting overcurrent greater than this value.

Thus, the magnetic protection device 9 allows instantaneous response to large point overcurrents, such as those resulting from short circuits, so that when such a short circuit occurs, the magnetic device 9 acts on the movable contact carrier 8 so as to cause the opening of the contacts 6,7, by the separation between the movable contacts 7 and the fixed contacts 6.

If the current flowing in the apparatus is below the established calibration limit, the portion of the current that passes through the bimetal 26 has the effect that it heats up and takes a steady state temperature in which it does not cause automatic triggering.

When an overcurrent occurs which exceeds the mentioned calibration limit, but does not reach the excessively high values as is the case for overconsumption in the controlled installation, the bimetal 26 signals said overcurrent by a greater heating, said bimetal then undergoes a bending which allows to trigger the initiation of the opening of the contacts at these levels of overcurrent.

When it bends, the so-called active bimetal 26 releases the compensating bi-metal 27, so that the latter operates the transfer bar 11, thereby causing the contacts 6.7 to open.

Thus, when strong overcurrents, such as those resulting from short-circuits, occur, the coil 25 gives rise to a magnetic trip opening of the contacts of the device, whereas when overcurrents occur of lower value which originate from overconsumption in the controlled installation, the active bimetal 26 gives rise, via the compensation bimetal 27, to a thermal tripping which likewise causes the opening of the contacts.

Note that in a manner known per se, a screw is provided, by means of which one can adjust the voltage of the bimetal to adapt the bending of the latter as a function of temperature.

The compensating bi-metal 27 makes it possible, in a manner known per se, to compensate for the variations to which the changes in the ambient temperature can give rise in the behavior of the active bimetal 26, so that the thermal tripping always occurs in accordance with the intensity of the nominal calibration, ie by compensating for the variations that changes in the ambient temperature may cause in the temperature that the circuit takes under the effect of the current.

Thus, the active bimetal 26 is sensitive to the current flowing through it, while the bimetallic strip 27 is sensitive only to ambient temperature.

As illustrated more particularly in the figure 10 , the active bimetal 26 is fixed by one of its ends on a support said first 30. According to the invention, and as illustrated on the Figures 3 to 9 , the bimetallic strip 27 is mounted in a second said insulating support 28, comprising at one of its ends a bearing portion 36 adapted to receive the hinge pin 29 of the bimetallic strip 27, said pin being integral with the said first support 30, which is intended to be fixed on the plate P.

This bimetallic strip 27 is fixedly mounted in a housing 28a of the support part 28, by plugging 37, so that said bimetallic compensation can move in a space e in a direction substantially perpendicular to the plane in which it s' extends, this functional game allowing only a limited deflection of the bimetallic strip. Thus, according to the invention, this support part 28 makes it possible to prevent the transmission of the thermal radiation to the active bimetal 26.

According to a very advantageous embodiment of the invention, this support part is multifunctional, comprising a screen part, a part intended for rearming, and a bearing part.

According to this embodiment, the bimetallic strip is in direct contact only with a plastic material, which limits the conduction phenomena.

The two bimetallic strips are connected to each other at their free ends facing each other by means of an attachment device 31.

A spring 32 ( fig.12 ) is intended to be mounted around the bearing portion 36 of the insulating support 28, being supported by one of its ends, on the so-called first support 30, and by its opposite end, on the insulating support said second 28 housing the bimetallic strip 27, so that when the attachment device 31 is deactivated, the spring 32 recalls the bimetallic strip 27 in a position in which it presses on the transfer bar 11 so as to cause a triggering of the device that opens the contacts.

The second axis of rotation 33 of the shaft 8 movable contact carrier and the axis of rotation said first 29 of the bimetallic strip 27 are brought closer to each other and extend substantially parallel to each other. report to the other. And the movable contact shaft-holder 8 is integral with a so-called first part 34 adapted to cooperate with a so-called second part 35 integral with the insulating support 28 of the compensating bimetallic strip 27 so as to recall this compensating bimetallic strip in a position of engagement with the active bimetal 26 against the aforementioned spring 32.

Advantageously, this so-called first piece 34 and this so-called second piece 35 are integrally formed respectively with the movable contact holder shaft 8 and with the insulating support 28 of the compensation bimetallic strip 27.

The operation of a current-breaking device according to the invention will be described in the following with reference to the Figures 13 to 15 .

On the figure 13 , the mechanism 1 of the device is in the closed position not triggered.

In this position, the two bimetals 26,27 are secured by the attachment device 31, and the two parts respectively first 34 and second 35, are spaced apart from each other.

When an overcurrent occurs which exceeds the mentioned calibration limit, but does not reach the excessively high values as is the case for overconsumption in the controlled installation, said overcurrent causes a greater heating of the bimetal 26. It results in a differential deflection between the active bimetallic strip 26 and the bimetallic strip 27 which makes it possible to deactivate the fastening device 31.

The return spring 32 comes into action so as to drive the piece 28 supporting the compensating bimetallic strip 27 and thus, the bimetallic strip, in rotation about the so-called first axis 29, towards a position in which it acts on the transfer bar 11.

In this position illustrated on the figure 14 the so-called first 34 and second 35 pieces are in a close position, but not in contact.

This corresponds to an instantaneous position in which the piece 28 has finished acting on the piece 11, but in which the opening of the contacts has not yet taken place.

It follows a rotation of the contact carrier 8 to a position in which the contacts 6.7 are open, this position being illustrated on the figure 15 .

During this rotation of the shaft 8 movable contact holders in the counterclockwise direction, towards the open position of the fixed and movable contacts 6 and 7, the so-called first part 34 comes into contact with the so-called second part 35 and causes this last and thus the bimetallic strip 27 in a clockwise rotation to restore the latching between the two bimetals 26,27, which corresponds to a rearm position bimetallic illustrated on the figure 7 .

Of course, the invention is not limited to the embodiments described and illustrated which have been given by way of example.

Thus, the invention applies to any thermal tripping device, as well as to any electrical device for cutting the current comprising it, said device comprising an active bimetallic strip and a bimetallic strip.

Claims (12)

1. Thermal trip device for an electrical current breaking apparatus housed in an insulating housing and comprising at least one single-pole phase assembly (2, 3, 4, 5) and one control mechanism (1), said single-pole phase assembly comprising a breaking chamber housing a fixed contact (6) and a moving contact (7), the different moving contacts (7) of the different assemblies being borne by a moving contact-holding shaft (8), these moving contacts (7) being able to be brought into an open position manually or automatically via, for each subassembly, a thermal protection device (10) suitable for actuating the control mechanism (1) so as to open the contacts upon the occurrence of an overcurrent in the circuit to be protected, said thermal protection device (10) comprising, on the one hand, a so-called active bimetal strip (26) suitable for producing an overheating when an overcurrent occurs above a certain level above the rated current value, this overheating leading to a thermal tripping of the control mechanism (1) of the apparatus so as to result in an opening of the contacts, and on the other hand, a so-called compensation bimetal strip (27), intended to compensate the variations that the changes of the ambient temperature determine in the temperature of the circuit, the compensation bimetal strip (27) being mounted to rotate about a so-called first fixed axis (29) belonging to a support of the so-called first apparatus, the two bimetal strips being secured to one another at one of their ends by means of an attachment device (31), this attachment device (31) being deactivated upon the occurrence of an overcurrent, this deactivation resulting in the actuation by the compensation bimetal strip (27) of the control mechanism (1),
   characterized in that the compensation bimetal strip (27) is mounted in a fixed manner at least partly in a recess (28a) provided in an insulating electrical support-forming part (28), said support (28) being arranged relative to the active bimetal strip (26) in such a way that it forms a screen suitable for protecting the compensation bimetal strip (27) from the thermal radiation generated by the active bimetal strip (26).
2. Device according to Claim 1, characterized in that the abovementioned compensation bimetal strip (27) is at least partly plugged into said part (28).
3. Device according to Claim 1 or 2, characterized in that the abovementioned recess (28a) comprises a space (e) suitable for allowing a limited deflection of the compensation bimetal strip (27).
4. Device according to any one of the preceding claims, characterized in that the abovementioned support-forming part (28) is made of plastic.
5. Device according to any one of the preceding claims, characterized in that this support-forming part (28) comprises, in the vicinity of a so-called first of its ends, a bearing-forming part (36) suitable to be mounted to pivot about the axis of rotation (29) of the compensation bimetal strip (27), said axis (29) being fixed to a fixed support (30) of the apparatus.
6. Device according to Claim 5, characterized in that the active bimetal strip (26) is fixed by a so-called first of its ends, situated facing the so-called first end of the support-forming part (28), to the abovementioned fixed support (30) of the apparatus, the bearing-forming part (36) making it possible to avoid the thermal conduction between the active bimetal strip (26) and the compensation bimetal strip (27) via the axis of rotation (29) of the compensation bimetal strip (27).
7. Current breaking apparatus comprising a thermal trip device according to any one of Claims 1 to 6.
8. Current breaking apparatus according to Claim 7, characterized in that this support-forming part (28) co-operates with a re-arming device (34, 35) suitable for returning the attachment device (31) to the activated position after the opening of the contacts following the occurrence of an overcurrent.
9. Apparatus according to Claim 7 or 8, characterized in that the so-called second axis (33) of rotation of the moving contact-holding shaft (8) and the so-called first axis (29) of rotation of the compensation bimetal strip (27), are brought into proximity of one another and extend substantially parallel to one another and in that the moving contact-holding shaft (8) comprises a so-called first part (34) co-operating with a so-called second part (35) secured in rotation to the compensation bimetal strip (27), these two parts (34, 35) being arranged relative to one another in such a way that, after a tripping of the mechanism (1), when the moving contact-holding shaft (8) is driven in the direction of the opening of the contacts (6, 7), the so-called first part (34) drives the so-called second part (35), and therefore the compensation bimetal strip (27), in rotation in a direction opposite to that having resulted in the tripping of the mechanism (1), until the reattachment of the two bimetal strips (26, 27) relative to one another is obtained.
10. Apparatus according to Claim 9, characterized in that it comprises return means (32) for returning the compensation bimetal strip (27) to a position of tripping of the control mechanism (1).
11. Apparatus according to Claim 10, characterized in that these return means comprise a spring (32) bearing by one of its ends on the so-called first support (30) of the axis of rotation (29) of the compensation bimetal strip, and by its opposite end on the insulating support-forming part (28) housing the compensation bimetal strip (27).
12. Apparatus according to any one of Claims 7 to 11, characterized in that it is a main circuit breaker.

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