EP3109878B1 - Vacuum interrupter and electrical protection apparatus comprising such an interrupter - Google Patents

Description

TECHNICAL AREA

The present invention relates to a vacuum interrupter comprising a cartridge elongated under vacuum, said cartridge comprising a cylindrical envelope closed by two so-called first and second bottoms respectively, in which are housed two arcing contacts of which one fixed is integral with one said first, aforementioned funds, while the other, mobile, is mounted at the end of a rod mounted to slide axially inside the cartridge, through the bottom said second, between a first position called closed bulb in which the arcing contacts are butt and open position of the bulb in which the arcing contacts are separated, and a compression spring capable of exerting a contact pressure force on the movable arc contact in the closed position of the arc contacts.

The present invention also relates to low or medium voltage electrical protection equipment such as a switch or a circuit breaker comprising such a bulb.

STATE OF THE PRIOR ART

Vacuum circuit breakers, such as those described in the document, are known FR 2721434 comprising housed in a sealed enclosure filled with a dielectric gas, a so-called main circuit having two main contacts, and a so-called secondary circuit having two said so-called arc contacts connected in parallel with the main contacts. This main circuit is intended to be traversed by the permanent current while the secondary circuit is intended to hold the short-circuit current before and during the opening of the contacts and the transient recovery voltage after the opening of the main contacts and the transfer of current to the arcing contacts.

In this type of apparatus, it is customary to provide the provision of an additional contact pressure spring for counteracting the repulsive forces generated by the current flowing through the arcing contacts during the break.

Apparatuses known as vacuum interrupters are also known as described in the documents WO 2006074975 , EP 2182536 in which only the breaking of the nominal current is carried out inside the vacuum interrupter.

In such devices, the contact pressure is usually provided by the pressure difference between the outside and the inside of the vacuum bulb.

In this case, the repulsive force generated by the current flowing inside the bulb is not sufficient to modify the value of the contact force. Thus, there is no reason to use an additional contact spring as is the case for circuit breakers.

However, such a vacuum interrupter connected in parallel with the main contacts has to face two main constraints, which are as follows:
When manufacturing the cartridge of the bulb on a large scale, it must be taken into account that dispersions along the length of the ceramic tubes of which the cartridges are constituted, can be observed, which will directly impact the contact pressures.

During the operation of the moving contacts, vibrations can be transmitted inside the bulb and generate micro loss of contact, in the absence of other devices than the local atmospheric pressure to maintain the contacts end to end.

These two constraints can be amplified if the bulb is used under an uncontrolled atmospheric pressure and in particular in the case of a high altitude installation.

In this case, it is possible to add a contact pressure spring at the end of the moving contact, as is the case for some light bulbs. Vacuum used in circuit breakers. However, this solution has the disadvantage of considerably increasing the length of the device consisting of the bulb, the spring and the movable contact, while the objective is to make more compact the switch with its bulb connected in parallel.

The document is also known JP S43 12016 describing a vacuum interrupter having the features of the preamble of claim 1.

SUMMARY OF THE INVENTION

The present invention solves this problem and proposes a vacuum interrupter and an electrical protection device having it having an improved contact pressure without increasing the size of the bulb.

For this purpose, the subject of the present invention is a vacuum interrupter according to claim 1.

According to a particular characteristic, the aforementioned guiding device is fixed to the so-called second bottom wall of the bulb.

According to another characteristic, the aforementioned spring is supported by one of its ends, on the aforementioned guide device and at its opposite end, on the moving arc contact.

According to another feature, this bulb further comprises a sealing bellows mounted around the rod and intended to seal between the inner portion of the bulb and the outside of the bulb, and the aforesaid spring is mounted within the aforementioned bellows.

According to another characteristic, said bellows is fixed sealingly, by one of its ends said first, on said second said bottom, and its opposite end, said second, to the aforementioned rod. Advantageously, this bellows is fixed by its so-called second end to a bellows support, which is fixedly mounted around the rod.

According to another characteristic, the aforementioned guiding device is fixed to said second said bottom wall by means of a dome-shaped fastening element, said dome having an orifice through which it is mounted around the stem and being fixed by its base on the so-called second bottom wall of the bulb, this cupola being intended to receive the annular portion of the guiding device, this guiding device being fixed to the so-called second bottom wall, by crimping this annular portion and dome.

According to a particular embodiment, the above-mentioned guiding device and the aforementioned fastening element form an integral part of a pre-existing part belonging to the bulb, which piece thus ensures the functions of guiding the rod, and of maintaining and positioning of the aforementioned compression spring inside the bulb.

The present invention also relates to a low or medium voltage electrical protection apparatus comprising a vacuum interrupter having the above-mentioned characteristics taken alone or in combination.

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

SUMMARY OF THE INVENTION

• La figure 1 est une vue en coupe axiale d'une ampoule à vide selon l'invention, avant le montage du ressort et de l'élément de guidage du ressort, en position fermée des contacts,
• La figure 2 est une vue en coupe axiale de cette même ampoule, après le montage de ces deux éléments, toujours en position fermée des contacts,
• La figure 3 est une vue en coupe axiale de cette même ampoule en position ouverte des contacts,
• La figure 4 est une vue en coupe axiale de l'élément de guidage seul,
• La figure 5 est une vue de face du ressort,
• La figure 6 est une vue en coupe axiale du soufflet d'étanchéité situé à l'intérieur ce cette ampoule,
• Les figures 7 et 8 sont respectivement une vue en perspective et une vue en coupe axiale, d'un dispositif de fixation de l'élément de guidage précité à l'intérieur de l'ampoule, selon l'invention, et
• Les figures 9,10 et 11 sont respectivement trois vues en perspective illustrant respectivement trois étapes successives permettant la mise en place et la fixation de l'élément de guidage précité.

But other advantages and features of the invention will appear better in the detailed description which follows and refers to the accompanying drawings given by way of example and in which:

• The figure 1 is an axial sectional view of a vacuum interrupter according to the invention, before the spring and the spring guide element are mounted, in the closed position of the contacts,
• The figure 2 is an axial sectional view of the same bulb, after the assembly of these two elements, always in the closed position of the contacts,
• The figure 3 is an axial sectional view of this same bulb in the open position of the contacts,
• The figure 4 is an axial sectional view of the guide element alone,
• The figure 5 is a front view of the spring,
• The figure 6 is an axial sectional view of the sealing bellows located inside this bulb,
• The Figures 7 and 8 are respectively a perspective view and a view in axial section, of a fixing device of the aforementioned guide element inside the bulb, according to the invention, and
• The Figures 9,10 and 11 are respectively three perspective views respectively illustrating three successive steps for the establishment and fixing of the aforementioned guide element.

In the figures, we see a vacuum bulb A for use in low or medium voltage electrical protection equipment such as a circuit breaker or an electrical switch. This bulb is generally disposed in a branch circuit connected in parallel with a circuit said main comprising the main contacts of the aforementioned apparatus. When this bulb is integrated in a circuit breaker, these arc contacts are intended to hold the short-circuit current, while when this bulb is integrated in a switch, it is intended to ensure the power cut.

In a manner known per se, this bulb A comprises a vacuum elongated cartridge comprising a cylindrical envelope 1 closed by two funds 2,3. The two aforementioned arc contacts 4,5 comprise a first arcing contact 4, said fixed, integral with one of the two funds, while the other arcing contact 5, said moving contact, is mounted in end of a rod 6, which rod 6 is slidably mounted through the other 3, said second, of the two funds, through a guide member 7 fixed relative to said second bottom 3 and passing through an opening 8 provided in said bottom 3.

This so-called mobile arc contact 5 is thus able to be displaced by means of said control rod 6 between a so-called open position remote from the fixed arc contact 4 and a so-called closed position in which these two contacts are brought together and in contact in order to allow the passage of the current.

Such a bulb also comprises a so-called sealing bellows 9 intended to ensure the seal between the inner part of the bulb and the part outside of the bulb while moving the stem. This bellows 9 is mounted around the rod and is supported by one 9a of its ends 9a, 9b, on the bottom 3 said second of the casing 1 and, by its opposite end 9b, on a portion 5a of the rod 6 located at the rear of the moving arc contact 5 via a support member 10 of the bellows 9, this support being fixedly mounted around the rod and on which is fixed this end 9b of the bellows. This support is supported on the rear face 5a of the movable arc contact 5. This support element 10 of the bellows is shown separately on the figure 6 and has a cylindrical portion 10a partly closed by a bottom portion 10b having an opening 10c adapted to allow the passage of the rod 6, and whose free edge is extended by a portion 10d extending substantially parallel to the wall of the bottom 10b and forming a bearing surface and fixing for the end 9b of the bellows.

This bulb also comprises a spring 11, said contact pressure spring, adapted to ensure a certain contact pressure between the stationary and movable arcing contacts in the closed position of the contacts.

This spring 11 is supported by one 11a of its ends, on the aforementioned rear face 5a of the movable arcing contact 5, via the aforementioned bellows support member 10 on which it rests, and by its opposite end 11b, on the free end 7a of said guide element 7, this element being shown separately on the figure 4 .

This guide element 7 comprises a cylindrical portion 7b, one of the free edges 7a cooperates with the spring 11, while the other free edge 7c is extended by an annular portion 7d extending in a plane extending substantially perpendicularly. to the axis of the rod 6. This annular portion 7d is intended to bear on the outer face 3a of the bottom wall 3, said second of the bulb, by means of a fixing support 12, in cupola shape having an orifice 12a, this support being shown separately on the Figures 7 and 8 , which support is intended to allow the fixing of the guide member 7 on said bottom wall 3 by crimping, as will be explained in the following.

The assembly of a bulb according to the invention will be described in the following with reference to the figures.

On the figure 1 which also corresponds to the figure 9 , the bellows support 10 and the bellows 9 have been mounted around the rod 6, then the so-called second bottom wall 3 mounted around the free outer end of the rod 6 and fixed on the corresponding free edge of the cylindrical envelope 1 of the bulb A.

Then, the cupola support 12 is mounted around the outer free end of the rod 6 and fixed to the so-called second bottom wall 3 by brazing. Then, the contact pressure spring, or compression spring 11, is also mounted around the rod 6, and brought to bear, by one of its free ends, on the bellows support 10.

Then, the guide element 7 of the spring 11, is in turn mounted around the rod 6 to come into contact with the spring, as illustrated on the figure 10 . In this position, the annular portion 7d is housed inside the dome 12.

After which, this guide element 7 is fixed by crimping, as illustrated in FIG. figure 11 , so as to bring the material belonging to the dome 12 on the guide member 7 and thus immobilize the latter relative to the so-called second bottom wall 3 of the bulb A.

The bulb A thus obtained is as shown on the figures 2 and 3 with the bulb in the closed position on the figure 2 , and in the open position on the figure 3 .

Thus, one of the surfaces on which the spring 11 is based is constituted by the free end 7a of the guide element 7, which surface has a fixed position relative to the bulb A, while the other The bearing surface of the spring 11 is constituted by a face 5a of the movable arc contact 5, this surface being mobile.

Thus, according to this embodiment of the invention, a compression spring is inserted into the housing of the bellows and held in place and in position by the guide device of the movable contact.

As this spring is limited in size, this provision therefore implies a very precise calculation of the contact pressure force which is necessary both to compensate for the assembly of the bulb and to compensate for the micro loss of contact.

According to another non-illustrated embodiment of the invention, the guiding device and its attachment support on the envelope of the bulb, are an integral part of a pre-existing part of the bulb, which part is fixed relative to the envelope of the bulb, so that this part performs the functions of guiding the rod supporting the movable contact, and maintaining and positioning the compression spring in the bulb. This embodiment makes it possible to obtain a reduction in the number of parts and thus a reduction in the manufacturing cost of this bulb.

It has therefore been realized thanks to the invention a vacuum bulb for solving the two previously mentioned constraints on the one hand to the dispersions along the length of the ceramic tubes and on the other hand, the presence of vibrations if the contacts are not not maintained end to end, while maintaining the compactness of the bulb.

The invention therefore makes it possible to remain in the bulk of the vacuum interrupter while having an improved contact pressure.

The invention applies advantageously but not exclusively to a vacuum interrupter intended to be integrated in a switch, but could also be used in a circuit breaker in addition to another contact pressure device.

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

Claims (10)

1. Vacuum interrupter of the kind comprising an elongate cartridge under vacuum, said cartridge comprising a cylindrical jacket (1) blocked by two end walls (2, 3), respectively called first and second, in which are housed two arc contacts (4, 5) of which one (4), which is fixed, is secured to one, called first, of the abovementioned end walls, while the other (5), which is mobile, is mounted at the end of a rod (6) mounted to slide axially inside the cartridge, through the other of the end walls, called second (3), between a first so-called closed position of the interrupter in which the arc contacts (4, 5) are end-to-end and an open position of the interrupter in which the arc contacts are separated, and a compression spring (11) suitable for exerting a contact pressure force on the mobile arc contact (5) in the position of closure of the arc contacts (4, 5),
   said abovementioned compression spring (11) being mounted inside the interrupter A around the rod (6), and bearing, by one (11a) of its ends (11a, 11b), on the mobile arc contact (5), and, by its opposite end (11b), on a part (7) fixed relative to the jacket (1) of the interrupter A, this fixed part (7) ensuring the holding and the positioning of the spring (11) inside the interrupter A and comprising a device for guiding the rod (6) inside the interrupter A, said device being mounted around the rod (6), the fixed part (7) comprising a cylindrical portion (7b) of which one (7a) of the free edges is intended to cooperate with the mobile arc contact (5), while the other free edge (7c) is folded in bracket form so as to form an annular wall (7d) extending in a plane substantially at right angles to the axis of the abovementioned cylindrical portion (7b), the abovementioned cylindrical portion (7b) being intended to be mounted around the rod (6);
   characterized in that the abovementioned cylindrical portion is intended to be mounted inside the interrupter A, while the abovementioned annular portion (7d) is intended to be brought to bear on the outer face (3a) of the abovementioned so-called second end wall (3).
2. Vacuum interrupter according to Claim 1, characterized in that the abovementioned guiding device is fixed to the so-called second end wall (3) of the interrupter A.
3. Vacuum interrupter according to Claim 1 or 2, characterized in that the abovementioned spring (11) bears, by one (11b) of its ends (11a, 11b), on the abovementioned guiding device and, by its opposite end (11a), on the mobile arc contact (5).
4. Vacuum interrupter according to any one of the preceding claims, characterized in that it further comprises a sealing bellows (9) mounted around the rod (6) and intended to ensure the seal-tightness between the internal part of the interrupter A and the outside of the interrupter, and in that the abovementioned spring (11) is mounted inside the abovementioned bellows (9).
5. Vacuum interrupter according to Claim 4, characterized in that the abovementioned bellows (9) is fixed in a seal-tight manner, by one (9a) of its end walls, called first, onto the abovementioned so-called second end (3), and by its opposite end (9b), called second, to the abovementioned rod (6).
6. Vacuum interrupter according to Claim 4 or 5, characterized in that the abovementioned bellows (9) is fixed by its so-called second end (9b) to a bellows support (10), which is fixedly mounted around the rod (6).
7. Vacuum interrupter according to any one of Claims 2 to 6, characterized in that the abovementioned fixed part (7) is fixed to the abovementioned so-called second end wall (3) via a fixing element (12) in the form of a dome, this dome comprising an orifice (12a) by which it is mounted around the rod (6) and being fixed by its base (12b) onto the so-called second end wall (3) of the interrupter, this dome being intended to receive the annular portion (7d) of the fixed part (7), this fixed part being fixed to the abovementioned so-called second end wall (3), by crimping this annular portion (7d) and the dome (12).
8. Vacuum interrupter according to Claim 1, characterized in that the abovementioned guiding device and a fixing element in the form of a dome, this dome comprising an orifice by which it is mounted around the rod (6), form an integral part of a pre-existing piece belonging to the interrupter, which piece thus ensures the functions of guiding the rod, and of securing and positioning the abovementioned compression spring inside the interrupter.
9. Low- or medium-voltage electrical protection apparatus comprising a vacuum interrupter A according to any one of Claims 1 to 8.
10. Electrical protection apparatus according to Claim 9, characterized in that it is a switch or a circuit breaker.

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