EP1816665B1 - Latch mechanism with movable pivoting axis - Google Patents

Abstract

The mechanism has movable contacts (4) connected rigidly to a contact holder (17) and pivoted between two positions of a fixed contact. A movable trigger (5) has a ratchet (9) maintaining a connecting rod (3) by supporting against the holder in locking and unlocking positions. A spiral spring (6) is constituted of end branches (16a, 16b), where the branch (6b) is connected to the holder by a welded portion to displace a pivoting axle with respect to support zones of the contacts. The branch implements a pressure support for each movable contact on the fixed contact.

Description

The present invention relates to a lock mechanism for electrical protection apparatus lines and persons of circuit breaker type comprising at least one movable contact designed to cooperate with one or more fixed contacts. Such a mechanism is movable between a locked closed position and an unlocked opening position of the line or lines controlled by the electrical apparatus.

The latter comprises an operating member that allows the control of a change of position of the lock mechanism and reflects if necessary an unlocking thereof for example due to the appearance on at least one line of electrical conditions incompatible with the maintaining the locked position. The operating member is conventionally connected to the lock mechanism by means of a connecting rod.

Traditionally, a lock mechanism comprises at least one movable contact supported by a contact carrier (s) pivoting along a first axis between two positions respectively in support and at a distance from a fixed contact. When locking the mechanism, a force from one end of the rod, from the actuator, is transmitted to the contact carrier (s).

Lock mechanisms have the function of mechanically amplifying the energy provided by measurement systems, and their principle of amplification is based on a mechanical system powered by a spring, whose unstable equilibrium is ensured essentially by forces friction. These are in particular implemented at the aforementioned end of the rod and the contact carrier (s).

In the event of a problem on the line, a moving trigger passes back to the mechanism information that is given by one of the measurement systems, usually magnetic or thermal, in order to unlock it when it is in the closed position of the contacts. This trigger includes a member for maintaining the link resting on the contact carrier (s), in the locking phase and in the locked position.

As the trigger moves and releases the end of the linkage, the frictionally stable mechanical relationship mentioned above is undone, allowing the mechanism to be unlocked.

Reminder means of the contact carrier (s) in the open position of each movable contact, that is to say at a distance from a fixed contact, are implemented as soon as the rod is released.

To ensure the stability of the lock mechanism in the closed position, it must have a deformable structure. The possibility of deformation is, in the known locks, provided by elastic means which generally allow a relative displacement between several parts and the implementation of a pressure support of each movable contact on a fixed contact.

In addition to the mechanical stability of the lock in the closed position, these resilient means provide sufficient pressure to avoid electrical problems when closing the circuit, making the circuit breaker much more reliable and avoiding the progressive degradation of the fixed and movable contacts. These means allow the surplus absorption of wear of the contacts.

In certain known configurations, the return means of the contact carrier (s) in the open position, movable contact at a distance from the fixed contact, and the elastic means for implementing a pressure bearing of the one on the other are insured by two separate jurisdictions.

However, there are also configurations in which a single spring simultaneously performs both functions. This is the case of the system described in the patent EP 0 506 503 in the name of the applicant.

In both cases, the assembly of the entire lock, involving a particular positioning of the spring or springs, is generally not easy to automate, and therefore economically less favorable in terms of industrialization of the assembly of the devices. electric.

In the case where a spring is interposed between the movable contact and the contact carrier (s), the structure is more complex, in particular because of the number of parts to be assembled according to mobile links, and because the installation of the springs requires a wedging of their ends so that they ensure their recall function. This complexity has a direct impact on the cost of manufacturing the product.

This problem of mounting the ends of the spring is found elsewhere in the solution described in document EP 0 506 503 for the single spring used.

One of the objectives of the present invention is to reduce the cost of the industrialization of the devices, and thus to simplify as much as possible the lock mechanism itself, as well as its mounting in the devices. An original configuration has been designed to meet this objective.

One of the major benefits of the new design is to avoid adjustments once the lock mechanism is mounted in the housing.

To satisfy these objectives, and others that will be apparent as the following description is read, the lock mechanism according to the invention is characterized principally by the fact that each movable contact is rigidly connected to the contact carrier ( s), and in that the elastic means for implementing the pressure support of each movable contact on a fixed contact are connected to the contact carrier (s) by a connection ensuring the displacement of the first pivot axis relative to at or the contact areas movable contact / fixed contact as soon as said support occurs.

The rigidity of the mobile contact / contact-carrier connection (s) allows a considerable simplification of the technical solution, as well as the industrialization process which only manages a rigid and compact assembly instead of several separate parts constituting the mechanism. lock as in most solutions of the prior art.

To ensure the stability of the lock in the locked position, according to a completely original solution, it is the axis of the initial pivoting of the contact carrier (s) which moves relative to the contact area movable contact / fixed contact. In other words, instead of ensuring a first displacement of the mechanism to bring the contacts in support, then a deformation about the same axis for pressing under pressure as in most solutions of the prior art, said deformation takes place with respect to the contact zone. This solution allows a significant technological simplification of the lock mechanism.

This can then comprise means for guiding the displacement of the first pivot axis.

According to a first variant, these elastic means consist of a pin spring with a rectilinear branch whose one end is fixed to the housing of the electrical apparatus, and whose other end is bent perpendicularly to said branch and ensures the pivot of the rotation of the contact carrier (s) according to the first axis by rotary adjustment of the bent portion in a port of the contact carrier (s).

In this case, the guide is provided by the spring itself, whose length of the branch is obviously invariable. There is no need to add external guidance elements.

Advantageously, this bent portion may further serve as a pivot to the trigger.

Furthermore, the return means of each movable contact at a distance from a fixed contact may consist of a pin spring with a branch whose one end is fixed to the housing of the electrical apparatus, said branch pressing the contact carrier (s) and exerting an antagonistic action to that of the rod.

These return means are then formed in the same way that the elastic means allowing the displacement of the first pivot axis, which they are however distinct.

This analogy is also found in the end of said branch, which is bent substantially perpendicular to the plane of movement of each movable contact, the end bent portion being this time housed in a slideway in the contact carrier (s).

The advantage of the slide is the ability to reorient the forces relative to the branch of the spring, so that it works over its entire length and not in compression, for which the stiffness is very high and unproductive.

Preferably, the pin springs respectively resilient means for implementing the pressure support and the return means of each movable contact respectively on and away from a fixed contact are in one piece, and are connected at their attachment to the housing.

As a result, there remains only one mounting point for the housing, of a single component, which further simplifies assembly.

More preferably, said springs can be connected by an additional branch. It can then be straight, developing substantially in the direction of movement of the free end of each movable contact.

In this case, the attachment to the housing is particularly facilitated because the spring, now in one piece, can be clipped into an outgrowth of the housing provided for this purpose.

The contact-holder / mobile contact assembly is thus no longer pivotable directly relative to said housing, but can be considered as "floating" with respect to the latter, provided with the possibility of moving in a complex non-moving motion. limited to a simple pivoting.

According to another variant, the elastic means for implementing an elastic support of each movable contact on a fixed contact consist of a spring comprising a pin-shaped branch, one end of which is connected to the housing of the electrical apparatus, said branch being positioned at rest so as to be deformed by the contact carrier (s) moving during locking as soon as a movable contact contact / fixed contact occurs, the contact carrier (s) being connected to the housing by a bonded connection inserted in a housing or a groove allowing its pivoting along the first axis and guiding its movement relative to the contact area movable contact / fixed contact.

In this case, the branch of the hairpin spring is not used for guiding the movements of the contact carrier (s), which is provided by the connection pad / housing or groove.

At this stage, it is only a question of elastic means allowing pressure support mobile contact / fixed contact.

The same branch may however be positioned at rest so as to be deformed by the contact carrier (s) during its entire movement, in order to also act as a means of return of each movable contact at a distance from a fixed contact. .

As in the previous configuration, the same spring is then used to achieve the return means of each movable contact at a distance from a fixed contact on the one hand, and the elastic pressure bearing means on the other hand.

One hypothesis is that one end of the hairpin branch is attached to the housing.

It is also possible that the hairpin branch is one of the end branches of a spiral spring whose spiral central portion surrounds a stud and the other end leg is in permanent support against a relief protruding from the housing. In this case, the mechanical connection of the hairpin branch with the case is certainly more complicated but present, as will be more apparent in the following, advantages at the time of assembly.

According to one possibility, the contact carrier (s) comprises a journal inserted in a rotating fit and sliding in a housing of the housing.

This connection ensures the mechanical functions specific to this connection, namely a pivoting along a first axis and a subsequent movement, the characteristics of said link to be combined with the return means described above for a return to the position initial release when the mechanism is unlocked.

The housing or the groove guiding the journal, in a movement that can be curvilinear and allow if necessary a friction of the movable contact on the fixed contact.

This housing comprises according to one possibility u-shaped walls oriented so that the opening of the U opens in the direction of the moving contact. Said housing is not completely closed, which can be seen as an additional advantage at the time of assembly.

More preferably, the spiral central portion of the spring surrounds the U-shaped housing.

In such a configuration, the location of the complex mechanical connection described above is also used as one of the attachment points of the spiral spring.

According to one possibility, the hairpin branch is driven by a pin protruding from the contact carrier (s).

The trigger pin with respect to the contact carrier (s) can be freely arranged on the contact carrier (s), provided that the function provided by the trigger is ensured. In this case, preferably, the trigger pivots about a pad coaxial with the movable pin in the housing housing, said stud protruding from the opposite face of the contact carrier (s).

There is therefore a single axis for the various pivoting involved in the contact carrier links with the boxes on the one hand, and the triggers with the contact carrier (s) on the other hand.

The contact carrier (s) may comprise conventionally a ramp on which rests one of the ends of the rod, said ramp cooperating with a pawl of the trigger to maintain the end of the rod resting on the ramp locking phase and locked position.

It is through this ramp that the force conveyed by the rod at the time of locking is transmitted to the lock mechanism. The existence of ratchet makes it possible to maintain the end of the rod in contact with this ramp, and therefore to transmit the effort.

According to one possibility, the movable contact (s) are in one piece with the contact carrier (s). In other words, there is no real contact carrier (s) but a reduced mechanism to one or more mobile contacts on which apply the efforts necessary to perform the functions of the mechanism.

According to one possible configuration, a bimetallic strip can be rigidly attached to the end of the or one of the movable contacts opposite its bearing zone against a fixed contact.

Alternatively, the bimetal can be in one piece with a moving contact, which further simplifies the moving assembly by removing one of its components.

In this case, the bimetallic / mobile contact is secured to the contact carrier (s) in the vicinity of the contact area movable contact / fixed contact, and comprises a bending section whose free end is disposed opposite a protrusion of the trigger. The bending section develops, from the securing means to the contact holder (s), opposite the contact zone along a certain length allowing sufficient flexion to actuate the trigger.

Preferably, the protrusion of the trigger is then placed in the vicinity of the member or pawl for maintaining the rod bearing against the contact carrier (s).

The lock mechanism, comprising in its purest version one or more movable contacts, a bimetallic strip and a trigger, becomes extremely compact and easy to mount, and is suitable for automating the assembly. The mechanism, mounted floating thanks to special connections that connect it to the housing, do not require any further particular adjustment later.

The pooling of certain functions, such as the pivot axis, the return spring and the elastic pressure support means in the first configuration, finally make it possible to achieve an economically extremely interesting lock mechanism.

• la figure 1 représente, en perspective, le mécanisme de serrure selon la première version avec un organe de manoeuvre pour sa commande ;
• la figure 2 montre, en vue perspective, la solution de la figure 1 implantée dans un appareil électrique du type disjoncteur ;
• les figures 3a et 3b montrent une autre configuration de la version des figures précédentes, implantée dans un disjoncteur respectivement en position de fermeture et d'ouverture des contacts ;
• la figure 4 est une vue en perspective plaquée d'une seconde variante basée sur un ressort spiralé ;
• les figures 5a et 5b représentent deux vues respectivement avant et arrière du mécanisme de la figure 4, les contacts séparés et en présence d'un moteur magnétique ;
• les figures 6a et 6b correspondent aux précédentes, avec les contacts fixe et mobile en appui en pression ; et
• les figures 7a à 7c montrent une alternative dans laquelle le contact mobile et le bilame sont une seule et même pièce.

The invention will now be described in more detail, with reference to the appended figures, for which:

• the figure 1 represents, in perspective, the lock mechanism according to the first version with an operating member for its control;
• the figure 2 shows in perspective the solution of the figure 1 implanted in an electric apparatus of the circuit-breaker type;
• the Figures 3a and 3b show another configuration of the version of the preceding figures, located in a circuit breaker respectively in the closed position and opening of the contacts;
• the figure 4 is a perspective perspective view of a second variant based on a spiral spring;
• the Figures 5a and 5b represent two views respectively front and back of the mechanism of the figure 4 the separate contacts and in the presence of a magnetic motor;
• the Figures 6a and 6b correspond to the previous ones, with the fixed and mobile contacts in pressure support; and
• the Figures 7a to 7c show an alternative in which the movable contact and the bimetallic strip are one and the same piece.

With reference to the figure 1 , the lock mechanism, designated by the general reference (1), is connected to an actuator (2) via a rod (3). The mechanism (1) consists primarily of a movable contact (4), a trigger (5) and a spring (6). The latter consists of three branches (6a, 6b, 6c) and ends with two bent portions (7a, 7b).

The portion (7b) serves as a pivot axis for the movable contact (4) and the trigger (5). The bent portion (7a) cooperates with the movable contact (4) via a slide (8) of parallel shape to the contact (4).

The trigger (5) comprises, at one of its ends, a pawl (9) for locking the end (3a) of the rod (3) bearing against a ramp (11) of the movable contact (4). At its opposite end, the trigger comprises a driver (10) provided to cooperate with a thermal bimetallic strip.

The lock mechanism represented in figure 1 is intended to be mounted in the housing of an electrical appliance, for example by clipping, the fixing being preferably at the level of the rounding separating the portions (6b, 6c) of the spring (6).

The whole of the figure 1 appears, on the opposite side and implanted in the case B of an electrical apparatus, in figure 2 . The operating member (2) is positioned so that the link (3) exerts an action, via its end (3a), against a ramp (11) of the movable contact (4) so as to pivoting against a fixed contact (12). This movement is carried out against the spring (6), and particularly its branch (6a), bearing via the bent portion (7a), in the slide (8), in the vicinity of the action zone of the end (3a) of the rod (3).

As soon as the movable contact (4) bears against the fixed contact (12), the deformation of the system, necessary for the mechanical stability of the locking, is effected by elastic displacement of the branch (6b) of the spring (6), and consequently by displacement of the bent end (7b).

The entire lock mechanism (1) moves inside the housing (B) of the electrical apparatus as soon as the movable contact (4) is supported on the fixed contact (12). This displacement makes it possible on the one hand to achieve a correct contact pressure between contact (s) fixed (s) and mobile (s), and also if necessary to make up the wear of the electrical contacts.

As this also appears in Figures 3a and 3b , the release (5) is rotatably mounted on the movable contact (4) around the pivot (7b) to release the end (3a) of the link (3) by moving the pawl (9) in case of occurrence of an overcurrent or short circuit on the line. In the event of a short-circuit, for example, the striker (14) of a traditional magnetic motor (M) can rotate it counter-clockwise, causing the release of the link (3) and the separation of the moving contacts. (4) and fixed (12) under the effect of the branch (6a) of the spring (6). The movable contact (4) further comprises a thermal bimetallic strip (13) rigidly attached to it at its end opposite to that which can bear on the fixed contact (12).

When an overcurrent occurs in the circuit, the bimetallic strip (13) deforms and comes into contact with the driver (10), which it causes by also causing a rotation of the trigger (5) in the same direction as before, and release of the link (3), ie the opening of the circuit.

The assembly of the mechanism of the lock (1) according to the invention, which makes it possible to ensure the pressure support of the movable contact (4) on the fixed contact, is achieved by means of a protrusion (15) emerging of the housing (B) and which clearly appears in figure 3b . This protuberance (15), in which is for example clipped the spring, is located at the rounded portion separating the bent portions (6b, 6c) of the spring (6).

Another version of the device according to the invention appears in the Figures 4 to 6 . The same references are retained when they concern the same components. With reference to the figure 4 , a control member (2) is connected via a link (3) to a contact carrier (s) (17) to which the movable contact (4) is rigidly connected, a trigger (5) being pivotally mounted around a pivot (18) protruding from the contact carrier (s) (17).

In this version, the spring (16) is a spiral spring having two end branches respectively (16a) and (16b), the latter being keyed in abutment on a relief (19) protruding from the housing B, the latter being in part occurrence symbolized by a rectangular portion of the envelope.

The other end (16a) of the spiral spring (16) cooperates with a stud (20) protruding from the contact carrier (s) (17) which urges the spring (16) when the contact carrier (s) rotates in the direction clockwise.

The central portion of the spiral spring (16) is wrapped around an inverted U-shaped housing (21) for accommodating a journal (22) protruding from the contact carrier (s) (17). This trunnion (22) is coaxial with the stud (18) around which the trigger (5) pivots.

The Figures 5a and 5b show in two opposite incidences the operation of the lock mechanism, the movable contact (4) being here at a distance from the fixed contact (12).

In the figure 5a in particular, the housing portion (B) and the U-shaped housing (21) are shown transparently for explanatory purposes. In this figure, the lock mechanism is unlocked, and the mechanical connection between the contact carrier (s) (17) and the housing (B) is defined by the trunnion system (22) / housing (21). An action on the control lever (2), in order to close the circuit, leads the end (3a) of the rod (3) to exert an action against the ramp (11). The contact-holder (17) / movable contact (4) / release (5) assembly pivots in the clockwise direction, the journal (22) being freely rotatable in the housing (21).

With reference to the figure 5b as the angular displacement increases from the above starting position, the end limb of the spring (16) flexes. Given the support of the other end (16b) against the stud (19), the spring (16) stores energy.

As soon as the movable contact (4) bears against the fixed contact (12), as shown in FIG. Figures 6a and 6b , and considering that the operating lever (2) on the one hand and therefore the rod (3) on the other hand continue their movement before the final locking in the locked position, the pin (22) moves in the housing ( 21) towards the exit of the U. However, the path is limited and remains inside the U-shaped wall. The entire mechanism then moves in the same way.

As in the version of Figures 1 to 3 a bimetallic strip (13) is rigidly mounted on the movable contact (4). Its deformations allow, by contact with the coach (10), the pivoting of the trigger (5), and consequently the release of the end (3a) of the rod (3). Said pivoting can also be triggered by the striker (14) of the magnetic motor (M).

The energy stored in the spring (16) during the previous rotation, for the purpose of locking, is then released, and the device returns to its initial position as illustrated in FIG. Figures 5a and 5b .

According to an alternative appearing Figures 7a to 7c , the bimetallic strip (13) and the movable contact (4) are only one piece (4 ') forming the two fractions. In this case, so that the bending of the blade can intervene in good conditions, it is necessary that the attachment (23) to the contact carrier (s) (17) is made close to the contact area movable contact (4). ') / fixed contact (12).

Bending is made to the control handle (2), and the trigger (5) now has either a driver (10), but a protuberance (10 ') located at the barrel of this controller, in the vicinity of the rod support zone (3) / ramp (11).

As for the previous bimetallic versions (13) fixed to the moving contact (4), this configuration eliminates any adjustment of the position of the bimetal after mounting the product.

Claims (24)

1. Lock mechanism (1) for electrical apparatus of the circuit breaker type protecting lines and individuals, comprising at least one mobile contact (4) intended to cooperate with one or more fixed contacts (12), the said mechanism (1) being mobile between a locked position closing the line or lines controlled by the electrical apparatus and an unlocked position opening them, a member (2) for operating it, making it possible to induce a position change of the mechanism (1) and revealing any unlocking due to the occurrence on at least one line of electrical conditions incompatible with keeping it closed, the said operating member (2) being connected via a rod (3) to the said locking mechanism (1), which comprises:

   - at least one mobile contact (4) supported by a contact holder (17) and pivoting about a first axis between two positions, respectively bearing on and at a distance from a fixed contact (12), a force coming from one end of the rod (3) being transmitted to the contact holder (17) with a view to locking the mechanism (1);

   - a mobile trigger (5) sending to the lock mechanism (1) the information given by a magnetic (M) or thermal measurement system (13) with a view to unlocking it when it is in the position closing the contacts (4, 12), the said trigger (5) having a member (9) for keeping the rod (3) bearing against the contact holder (17) in the locking phase and in the locked position;

   - means for returning the contact holder (17) into the position opening each mobile contact (4) at a distance from a fixed contact (12) in the event of the rod (3) being released, leading to the mechanism (1) being unlocked; and

   - resilient means for making each mobile contact (4) bear with pressure on a fixed contact (12) in order to absorb the wear of the contact (4, 12);

   characterised in that each mobile contact (4) is rigidly connected to the contact holder (17), and the resilient means (6b, 16) for making each mobile contact (4) bear with pressure on a fixed contact (12) are connected to the contact holder (17) by a connection (7b; 21, 22) which displaces the first pivoting axis with respect to the mobile contact (4)/fixed contact (12) bearing zone or zones as soon as the said bearing takes place.
2. Lock mechanism (1) according to the preceding claim, characterised in that it comprises means (7b; 21) for guiding the displacement of the first pivoting axis.
3. Lock mechanism (1) according to one of the preceding claims, characterised in that the said resilient means consist of a hairpin spring having a branch (6b) with a straight shape, one end of which is fixed to the housing (B) of the electrical apparatus and the other end (7b) of which is bent perpendicularly to the said branch (6b) and provides the pivot for the rotation of the contact holder about the first axis by rotational fitting of the bent portion (7b) into a hole of the contact holder.
4. Lock mechanism (1) according to the preceding claim, characterised in that the bent portion (7b) serves as a pivot for the trigger (5).
5. Lock mechanism (1) according to one of the preceding claims, characterised in that the means for returning each mobile contact (4) to a distance from a fixed contact (12) consist of a hairpin spring with a branch (6a) one of the ends of which is fixed to the housing (B) of the electrical apparatus, the said branch (6a) bearing on the contact holder and exerting there an action antagonistic to that of the rod (3).
6. Lock mechanism (1) according to the preceding claim, characterised in that the free end (7a) of the said branch (6a) is bent substantially perpendicularly to the displacement plane of each mobile contact (4), the bent end portion (7a) being accommodated in a slideway (8) formed in the contact holder.
7. Lock mechanism (1) according to one of Claims 3 to 6, characterised in that the hairpin springs (6b, 6a) of the resilient means for making each mobile contact (4) bear with pressure on a fixed contact (12), and of the means for returning each mobile contact (4) to a distance from a fixed contact (12), respectively, are integral and are connected where they are fastened to the housing (B).
8. Lock mechanism (1) according to the preceding claim, characterised in that the said springs (6b, 6a) are connected by an additional branch (6c).
9. Lock mechanism (1) according to the preceding claim, characterised in that the branch (6c) has a straight shape extending substantially in the displacement direction of the free end of each mobile contact (4).
10. Lock mechanism (1) according to one of Claims 1 and 2, characterised in that the resilient means for making each mobile contact (4) bear resiliently on a fixed contact (12) consist of a spring (16) having a hairpin branch (16a) one end of which is connected to the housing (B) of the electrical apparatus, the said branch (16a) being positioned at rest so as to be deformed by the contact holder (17) being displaced during locking as soon as mobile contact (4)/fixed contact (12) bearing takes place, the contact holder (17) being connected to the housing (B) by a stud connection (22) inserted into a socket (21) or a groove allowing it to pivot about the first axis and guiding its displacement with respect to the mobile contact (4)/fixed contact (12) bearing zone.
11. Lock mechanism (1) according to the preceding claim, characterised in that the said branch (16a) is positioned at rest so as to be deformed by the contact holder (17) throughout its full movement, with a view to also acting as means for returning each mobile contact (4) to a distance from a fixed contact (12).
12. Lock mechanism (1) according to one of Claims 10 and 11, characterised in that one of the ends of the hairpin branch is fixed to the housing (B).
13. Lock mechanism (1) according to one of Claims 10 to 11, characterised in that the hairpin branch (16a) constitutes one of the end branches of a coil spring (16), the coiled central portion of which encloses a stud (21) and the other end branch (16b) of which bears permanently against a projection (19) protruding from the housing (B).
14. Lock mechanism (1) according to one any of Claims 10 to 13, characterised in that the contact holder (17) comprises a journal (22) inserted with a rotational and sliding fit into a socket (21) of the housing (B).
15. Lock mechanism (1) according to the preceding claim, characterised in that the said socket (21) has walls erected in a U-shape so that the opening of the U faces in the direction of the mobile contact (4).
16. Lock mechanism (1) according to Claims 13 to 15, characterised in that the central coiled portion of the spring (16) encloses the U-shaped socket (21).
17. Lock mechanism (1) according to one of Claims 10 to 16, characterised in that the hairpin branch (16a) is driven by a pin (20) protruding from the contact holder (17).
18. Lock mechanism (1) according to one of Claims 14 to 17, characterised in that the trigger (5) pivots about a stud (18) coaxial with the mobile journal (22) in the socket (21) of the housing (B), the said stud (18) protruding from the opposite face of the contact holder (17).
19. Lock mechanism according to any one of the preceding claims, characterised in that the contact holder (17) comprises a ramp (11) on which one of the ends (3a) of the rod (3) bears, the said ramp (11) cooperating with a catch (9) of the trigger (5) in order to keep the end (3a) of the rod (3) bearing on the ramp (11) in the locking phase and in the locked position.
20. Lock mechanism (1) according to any one of the preceding claims, characterised in that the mobile contact(s) (4) is or are integral with the contact holder (17).
21. Lock mechanism (1) according to any one of the preceding claims, characterised in that a bimetallic strip (13) is secured rigidly to the end of the mobile contact or one of the mobile contacts (4), opposite to its zone bearing against a fixed contact (12).
22. Lock mechanism (1) according to any one of Claims 1 to 19, characterised in that the bimetallic strip (13) is integral with a mobile contact (4).
23. Lock mechanism (1) according to the preceding claim, characterised in that the bimetallic strip (13)/mobile contact (4) is secured to the contact holder (17) in the vicinity of the mobile contact (4)/fixed contact (12) bearing zone and comprises a bending segment, the free end of which is arranged facing an outcrop (10') of the trigger (5).
24. Lock mechanism (1) according to the preceding claim, characterised in that the outcrop (10') of the trigger is placed in the vicinity of the member (9) for keeping the rod (3) bearing against the contact holder (17).

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