EP0570647B1 - Switch latch for a circuit breaker and circuit breakers incorporating it - Google Patents

Abstract

Circuit breaker latch mechanism, of the type comprising an operating member (5) equipped with an actuating knob (5a) and normally pushed back into the open position of the contacts by a return spring (96), a connecting rod (39), one end of which is mounted eccentrically on the operating member (5), a contact holder (41) pivoting around an axis and having a ramp (54) against which the other end (39a) of the connecting rod (39) can come to bear and buttress, at least one moving contact (17, 29) mounted on the pivot axis of the contact(s) holder (41) so as to be able to pivot slightly relative to the latter so as to exert a contact pressure on a fixed contact (20, 35) and a pawl (42) pivoted on the contact holder (41). This pawl (42) is associated with a trip means (43) capable, when it is actuated, of causing the swinging of the pawl (42) and the release of the connecting rod (39), and optionally of driving the contact holder (41) into the open position for a forced wrenching of the moving contact (17, 29). Each moving contact (17, 29) is retained angularly on the pivot axis of the contact holder (41) by an elastic member (76) having a bearing point on the said pivot axis and at least two bearing points on the moving contact (17, 29), so as to urge the latter, with respect to the said pivot axis, in the direction of the contact pressure on the fixed contact (20, 35). <IMAGE>

Description

The present invention relates to a lock mechanism for a magneto-thermal circuit breaker or similar device, in particular for phase and neutral circuit breaker. It also relates to circuit breakers fitted with this mechanism.

Line protection circuit breakers include, in a housing, a circuit extending between two terminals and include a thermal trip bimetal for protection of the line against overloads and an electromagnetic tripping device comprising a coil with an associated plunger core to a striker, to ensure, in the event of a short circuit, the tripping by opening of a movable contact cooperating with one or more fixed contacts. The phase and neutral circuit breakers comprise, in addition to the phase stage as described, a neutral stage with fixed and mobile contacts, the mobile neutral contact being actuated jointly with the mobile phase contact.

The actuation of the movable contact is generally carried out by a locking mechanism, of the toggle type, usually comprising an operating member with a lever type lever actuated manually and causing a rod tending to push back a pivoting contact carrier which carries one or several movable contacts to bring them each in pressure contact against a fixed contact, up to a position in which the return in the opposite direction, towards the contact opening, is normally prevented by a pawl preventing the link, by pressing the toggle joint on the contact carrier, from escaping and to release this one. Manual opening is carried out by operating the handle in the opposite direction. The disjunction is generally caused by the action of the bimetallic strip or the striker of the coil against a trigger lever so as to cause the release of the pawl and therefore the escape of the link, and, in the case of magnetic disjunction, the forced opening of the contact carrier. The return spring of the contact carrier also serves to ensure the contact pressure.

Such a mechanism is described, for example, in the document FR-A-2 648 615. A mechanism according to the preamble of claim 1 is described in the document EP-A-0 224 396, which shows an elastic member being a spring of the pin type.

These mechanisms have a certain degree of complication and do not lend themselves to automatic manufacture due to the number of parts that constitute them and the spatial and functional constraints that are specific to them.

The present invention proposes to remedy these drawbacks and to provide a lock mechanism suitable for automated mounting in a circuit breaker, both in the case of a simple circuit breaker and in the case of a phase and neutral circuit breaker. .

Another object of the invention is to provide a lock mechanism making it possible, in the case of a phase and neutral circuit breaker, to assign independent contact pressures to the movable phase and neutral contacts.

Another object of the invention is to provide a particularly simple, inexpensive lock mechanism that takes up as little space as possible.

Finally, yet another objective is to be able to assemble the devices according to the invention along a single mounting axis.

The subject of the invention is therefore a mechanism according to claim 1.

The great novelty consists in the fact that it is no longer necessary to mount the lock mechanism as a sub-assembly ready to be assembled, since the two supports of the spring are on the movable contact. This means that this torsion type spring can be mounted on the movable contact without the contact carrier being attached to it. And therefore, the automation of the various elements of the moving assembly can be total.

Preferably, the elastic return member is a spring of the pin type.

More preferably, the pawl and the triggering means are made in one piece, in particular in molded plastic, and are pivoted on the pivot axis of the contact carrier (s).

In the case of phase and neutral circuit breakers, the contact carrier preferably has at least one pivot on which the pawl-tripping means assembly is placed and a movable contact with its elastic contact member. Preferably then, opposite said pivot, the contact carrier has a recess whose median axis is aligned with that of the pivot and by which the contact carrier can be pivotally placed on a shaft end carried by the circuit breaker housing and capable of receiving the other movable contact and its elastic contact member. It goes without saying that, instead of this recess, the contact carrier can also include another pivot for supporting a movable contact and its elastic contact member. The contact holder preferably being made of molded plastic, the pivot (s) can advantageously come from molding. However, it is understood that one can also use added pivots.

If necessary, the two elastic contact members can be of different strengths.

The pawl and the triggering means are preferably made in one piece from molded plastic. The rearming of the pawl, that is to say its return to the closed position, can advantageously be ensured by the return spring of the operating member.

In the case of phase and neutral circuit breakers, the contact carrier is made of molded plastic and has a transverse head serving to support the return spring of the contact carrier, separated from the body of the contact carrier by a light in V having said ramp-up ramp, and the body of the contact carrier has, on its lateral faces, the pivot and the recess respectively, as well as each time a finger located closer to the head than the pivot or the recess and, with respect to the latter, opposite the operating member.

Very advantageously, identical mobile contacts can be used, formed of metal parts with flat cross sections and comprising, in an enlarged part, a notch in the form of a secondary quasi-orifice engaging around the aforesaid finger and a lateral lug forming a fulcrum for the elastic contact member, the widened part being extended by an elongated part having the actual electrical contact point, and, on the opposite edge of said elongated part, a notch forming the second point of support for the elastic contact member.

The main orifice of the enlarged part is provided oblong, so that the elastic members perfectly play their role of increasing the pressure of the movable contact on the fixed contact.

The invention also relates to circuit breakers comprising such a lock mechanism.

Very advantageously, this lock mechanism lends itself perfectly to automated mounting piece by piece in a circuit breaker box, as is moreover apparent from the part of the description which follows and which relates to an mounting method. However, it goes without saying that such a mechanism could also be pre-assembled, in particular thanks to the use of a single added pivot axis.

• les figures 1 et 2 sont des vues en coupe longitudinale d'un disjoncteur de phase et de neutre selon l'invention, avec neutre à gauche, la figure 1 montrant l'étage de phase et la figure 2, l'étage de neutre;
• la figure 3 est une vue extérieure du disjoncteur selon les figures 1 et 2, montrant un petit côté dudit appareil;
• les figures 4 et 5 sont des vues en coupe longitudinale d'un disjoncteur de phase et de neutre selon l'invention avec neutre à droite, la figure 4 montrant l'étage de neutre et la figure 5, l'étage de phase;
• la figure 6 est une vue analogue à la figure 3, pour le disjoncteur selon les figures 4 et 5;
• la figure 7 est une vue éclatée d'un mécanisme de serrure selon l'invention ;
• les figures 8 à 12 sont des vues du mécanisme de serrure sans l'organe de manoeuvre, respectivement vue de droite, vue en coupe selon le plan de coupe IX-IX, vue de face, vue de gauche et vue en perspective de la vue de la figure 10 ;
• les figures 13 à 15 sont des vues partielles schématiques du disjoncteur selon l'invention, destinées à montrer le fonctionnement du mécanisme de serrure, les figures 13 à 15 représentant le mécanisme en position d'ouverture des contacts, en cours de fermeture des contacts et à l'état contacts fermés;

The invention will now be described in more detail using an embodiment of a phase and neutral circuit breaker and its method of assembly in neutral configuration on the left and neutral on the right, in conjunction with the drawing in which:

• Figures 1 and 2 are views in longitudinal section of a phase and neutral circuit breaker according to the invention, with neutral on the left, Figure 1 showing the phase stage and Figure 2, the neutral stage;
• Figure 3 is an external view of the circuit breaker according to Figures 1 and 2, showing a small side of said device;
• Figures 4 and 5 are views in longitudinal section of a phase and neutral circuit breaker according to the invention with neutral on the right, Figure 4 showing the neutral stage and Figure 5, the phase stage;
• Figure 6 is a view similar to Figure 3, for the circuit breaker according to Figures 4 and 5;
• Figure 7 is an exploded view of a lock mechanism according to the invention;
• Figures 8 to 12 are views of the lock mechanism without the operating member, respectively right view, sectional view along the section plane IX-IX, front view, left view and perspective view of the view of Figure 10;
• FIGS. 13 to 15 are schematic partial views of the circuit breaker according to the invention, intended to show the operation of the lock mechanism, FIGS. 13 to 15 showing the mechanism in the contact opening position, during the closing of the contacts and in the closed contacts state;

The circuit breakers according to the invention are preferably modular devices, that is to say whose width is equal to a multiple of a defined module. They usually include a housing having a base 1 provided with means 2 for fixing and / or clipping (with retractable latch, not shown) on a support rail, not shown, and a top 3 having an opening 4 for the passage of the actuating handle 5a of an operating member 5 of a lock mechanism which will be described later. The housing still usually has two short sides 6 and 7 having the electrical connection terminals and two large faces 8 and 9 called lateral faces, which are parallel to the median plane of the housing.

By convention, the left and right sides are defined with respect to the median plane of the device placed, by its base, against a vertical surface, with the actuating handle 5a in the "On" position upwards. By way of example, FIGS. 1 and 2 are partial left views of the interior of an apparatus according to the invention, and in FIG. 3, the right side of the sheet corresponds to the right side of the case, face 9.

We first refer to Figures 1 to 3 relating to a circuit breaker with neutral on the left.

In Figure 3, we see that the housing of this circuit breaker is formed of three parts, two left half-shells 10 and right 11 and an intermediate part forming a spacer 12 which will be described later.

The partial left views of FIGS. 1 and 2 reveal the phase and neutral stages of the circuit breaker respectively.

• un circuit de phase comportant d'une part une borne de raccordement 25 accessible par le petit côté 7 du boîtier, une tresse conductrice 26 reliée à une extrémité de la bilame thermique 27, dont l'autre extrémité est connecté à une seconde tresse conductrice souple 28 reliée au contact mobile 29, ce qui constitue le sous-ensemble thermique 30, et d'autre part, un sous-ensemble magnétique 31 comportant une borne de raccordement 32, accessible par le petit côté 6 du boîtier, et un moyen de disjonction électromagnétique à bobine de disjonction 33 et culasse 34, se prolongeant par un contact fixe 35;
• ce dernier ainsi que la lame 26 présentent chacun un prolongement formant des électrodes de commutation d'arc électrique ou lame de guidage d'arc, respectivement 37 et 36; et
• un sous-ensemble "déions" usuel 38 est placé entre ces deux électrodes 36 et 37.

The phase stage includes (Figure 1):

• a phase circuit comprising on the one hand a connection terminal 25 accessible from the short side 7 of the housing, a conductive braid 26 connected to one end of the thermal bimetal strip 27, the other end of which is connected to a second flexible conductive braid 28 connected to the movable contact 29, which constitutes the thermal sub-assembly 30, and on the other hand, a magnetic sub-assembly 31 comprising a connection terminal 32, accessible by the small side 6 of the housing, and a means of disjunction electromagnetic coil 33 and cylinder head 34, extending by a fixed contact 35;
• the latter as well as the blade 26 each have an extension forming electric arc switching electrodes or arc guiding blade, respectively 37 and 36; and
• a usual "deion" sub-assembly 38 is placed between these two electrodes 36 and 37.

• un circuit de neutre comportant d'une part un sous-ensemble contact mobile de neutre, sous la référence 13, incluant successivement une borne de raccordement 14, dite à cage, accessible par le petit côté 7 du boîtier, une lame conductrice 15, une tresse conductrice souple 16 et un contact mobile 17, et d'autre part un sous-ensemble contact fixe, sous la référence 18, incluant une lame pliée 19 présentant une partie formant le contact fixe proprement dit 20 et une borne de raccordement 21 accessible par le petit côté 6 du boîtier; dans chacun de ces sous-ensembles, comme dans ceux qui vont suivre, les éléments successifs sont reliés électriquement;
• les lames 15 et 18 présentent chacune un prolongement formant électrode de commutation électrique d'arc, respectivement 22 et 23;
• un sous-ensemble "déions" usuel 24 formant chambre d'extinction d'arc, constituée d'un empilement de tôles, est placé entre les deux électrodes 22 et 23.

The neutral stage includes (Figure 2):

• a neutral circuit comprising on the one hand a mobile neutral contact sub-assembly, under the reference 13, successively including a connection terminal 14, called a cage, accessible by the short side 7 of the housing, a conductive blade 15, a flexible conductive braid 16 and a movable contact 17, and on the other hand a fixed contact sub-assembly, under the reference 18, including a folded blade 19 having a portion forming the actual fixed contact 20 and a connection terminal 21 accessible by the short side 6 of the housing; in each of these subsets, as in those which will follow, the successive elements are electrically connected;
• the blades 15 and 18 each have an extension forming an electric arc switching electrode, respectively 22 and 23;
• a conventional "deion" sub-assembly 24 forming an arc extinguishing chamber, consisting of a stack of sheets, is placed between the two electrodes 22 and 23.

It can be seen that the phase and neutral terminals are respectively shifted in height, for the purpose of polarization.

The circuit breaker further comprises the above-mentioned operating member 5 with its actuating handle 5a, intended to act, by means of a link 39, on the lock mechanism 40 which mainly comprises a movable contact carrier 41 with a toggle joint device, cooperating with the link 39 and with a pawl 42 integral with a trigger lever 43, with the lock mechanism 40, which is biased by the coil 33 and by the bimetallic strip 27, in the latter case via a trainer 44.

In the case of a circuit breaker with neutral on the right, the general arrangement of the phase and neutral stages is the same as previously, except their place on either side of the median plane of the housing, as well as 'We can see in Figures 4 and 6. We note in particular the identical orientation of the various components in the plane of the housing, compared to the previous embodiment.

As a result, the left and right half-shells as well as the spacer are specific to the chosen configuration, neutral on the left or neutral on the right. For the present case, a left half-shell 10 'is used for the neutral side, a spacer 12' and a right half-shell 11 'for the phase stage.

We will now describe the lock mechanism 40 according to the invention, referring to FIGS. 7 to 15.

To simplify the presentation, we will consider, with reference to FIGS. 7 to 15, that this lock mechanism 40 generally comprises the movable contacts and the operating member 5 with its actuation handle 5a and its spring. recall 96.

The operating member has a pivot axis 45 and, laterally, an extension 46 pierced with a passage 47 parallel to said pivot axis 46 and in which one of the two end branches of the link can be articulated 39, which has a U shape. The return spring 96 has a first branch 96a secured to the operating member and a second branch 96b intended to bear against the pawl 42 to ensure rearming as will be seen below. .

The mechanism also includes the contact carrier 41 made of molded insulating material and having an upper transverse head 48 provided, opposite the operating member 5, with a bearing 49 serving to support a powerful return spring 50 of the contact carrier 41 in the open position of the contacts. Axially, the head 48 has a part 48a, connecting to the body 55 of the contact carrier 41 and having an elongated lumen 51, substantially V-shaped in cross section, the shape of which will appear better in FIGS. 11 and 12, and which receives the second end arm 39a of the link. The light 51 comprises a first part 52 which is substantially horizontal when the device is placed on its base 1 (see FIGS. 13 to 15), then, on the operating member side 5, a second part 53, descending and shorter, which characterized by an inclined thrust surface 54 cooperating with said second end arm 39a of the link 39. The assembly of the light allows the guided deflection inside thereof, of this end 39a of link, the part 52 forming a zone of exhaust.

The body 55 of the contact carrier 41 has on one side a cylindrical protuberance 56 forming a pivot (hereinafter pivot 56), which is characterized by two parts of different diameters, namely a part 57 of large diameter, body side 55, and an outer part 58, of smaller diameter. This pivot 56 is hollow and therefore has a first outer section 60 of large diameter extending by a second inner section 62, of smaller diameter.

In addition, the body 55 has laterally two arcuate shoulders 63, symmetrical to one another, one of which overhangs the part 58 of the pivot 56 and which both overhang fingers 64 also provided on each of the sides of the body 55 The upper surface of the body 55, with the same curvature as said shoulders 63, forms the transition surface between the two parts 52 and 53 of the lumen 51, with the pushing surface 54. This surface is made to allow passage and movement of the end 39a of the link.

The mechanism further comprises a molded plastic part which joins the pawl 42 and the trigger lever 43 and which has, on one of its faces and transverse to it, a cylinder trunk 65 whose light s' fits on the part 57 of the pivot 56 for pivoting mounting on the contact carrier 41. The pawl 42, formed by a protruding rim on the same side as the cylinder trunk 65, is intended to normally block the end 39a of the link 39 in the inclined part 53 of the light 51 and it can be erased so as to allow said rod end 39a to escape in the part 52 of the light 51, when the magnetic disjunction means are actuated or under the influence of the bimetallic strip. The return spring 96 then allows the pawl 42 to be reset under the action of the branch 96b when, starting from the disjunction position, the lever 5a is brought back in a trigonometric direction to the "On" position (FIG. 15).

Indeed, the trigger lever 43 has an intermediate surface 66 intended to be struck by the percussion rod or striker of the electromagnetic coil 33 and, at its end opposite to the previous one, a spout 67 mechanically connecting the bimetallic strip 27 to the lever 43 via the driver 44 (Figures 3 and 4) to ensure thermal disjunction.

The movable contacts 17 and 29, which can be neutral or phase depending on the embodiment of the circuit breaker, are identical and have, in a head 68, a main orifice 69, which is slightly oblong, intended to come on the axis pivoting mechanism, that is to say, in the embodiment described and shown (Figures 7, 9,10), either on the part 58 of the pivot 56 for the left movable contact, or on a tip shaft carried by a housing half-shell and coming to be placed in the recess 59 of the contact carrier 41, for the right movable contact. A notch in the form of a quasi-orifice 70 is also provided in the head 68 and is intended to be engaged on the finger 64 of the contact carrier 41, a finger which in reality acts as an axis of articulation of the movable contact when one arrives in the contact position. It should indeed be noted that the pivoting axis of the movable contacts is different from that of the lock, for reasons considered later.

The head 68 is extended by an elongated part 72 having the actual electrical contact point, reference 73, and, on the side opposite this last, a notch 74. Finally, on its edge opposite to said elongated part 72, the head has a lateral lug 71 coming from folding.

Each movable contact 17, 29 is associated with a powerful contact spring 76, having a turn, having two branches 77, 78 forming at rest a slightly obtuse angle, the branch 77 further comprising an end 79 folded at right angles to the outside. . This spring is shaped so as to normally maintain the movable contact on its axis and, in the closed position, to ensure the contact pressure on the corresponding fixed contact. The turn of the spring 76 is placed around the axis (pivot 56 or end of the shaft of the housing), while the branch 77, by its end 79, and the branch 78 engage in the notches 74 and against the lugs 71, respectively. The establishment of the spring is done under stress by bringing the two branches 77,78 towards one another.

The parts forming the contacts being identical whatever their mounting side, it goes without saying that for one, the spring 76 will be placed on the contact carrier side 41, and for the other, outside with respect to this last, as can be seen in particular in FIGS. 7 and 9.

We now refer to Figures 13 to 15.

The actuator 5 no longer being entirely in the "Stop" position, but in an intermediate position, shown in FIG. 13, the open contact position is guaranteed by the action in direct trigonometric direction of the powerful spring 50 on the assembly constituted by the contact carrier 41, the movable contacts 17 and 29 and the pawl 42. The free end 39a of the rod 39 is then held by the pawl 42 against the inclined thrust surface 54. The action of the pawl 42 is possible because the spring 96 brings it closer to the contact carrier.

When the operating member 5 is rotated in a trigonometric direction, the end 39a of the rod 39 pushes the inclined thrust surface 54 and thus makes the said assembly rotate clockwise against the action of the spring 50 until closing of the contacts, FIG. 14. The contact takes place before the extreme position of the member 5. From this moment, the head 68 of the movable contacts, until it abuts on the pivot 94 via a portion of orifice 69 takes off from this stop. The contact carrier 41 continues to rotate and the movable contacts bear more strongly against the fixed contacts under the action of their contact spring 76, while the operating member 5 reaches its extreme "On" position: this is the wear stroke.

This wear stroke is in particular intended to compensate for the play which would possibly result from the wear of the contacts, and which would create contact problems, making the circuit breaker much less reliable.

The stable position guaranteed by the toggle consisting of the lever 5 and the link 39 tends to press the lever against its stop.

If, with the contact in the closed position (FIG. 15), the driver 44 pulls the lower end of the lever 43 in a trigonometric direction, the pivoting of the latter moves the pawl 42 which releases the end 39a of the link 39. due to the inclination of the thrust surface 54, and under the simultaneous effect of the spring 50 and the reactions of the springs 76, the end 39a of the rod escapes towards the part 52 of the light 51 and the holder contacts 41 suddenly rotates counterclockwise, which leads to the opening of the contacts. This is what occurs following a progressive overload of the protected circuit, thus causing the deformation of the bimetallic strip and consequently the displacement of the driver.

If, starting from this same closed contact position in FIG. 15, a sudden overcurrent appears, this time it is the striker of the coil 33 which strikes the surface 66 of the lever 42, and the latter switches in a trigonometric direction , which releases the pawl 42 and the link 39 as before.

It should be noted that there is recovery of the wear stroke only when the striker is at the end of the stroke. At this time, there is no longer any support between the fixed contacts and the movable contacts, which have a sufficient distance between them so that the arc created can start towards the breaking chamber.

It is only after the striker has reached its end position that the wear stroke is recovered. In this way, there is no chronological interference between the disjunction phase and the recovery phase of said wear stroke, which would obviously delay, otherwise, the dynamic spacing of the contacts.

Claims (13)

1. Circuit-breaker lock mechanism of a type comprising at least one moving contact (17, 29) cooperating with one or more fixed contacts (20, 35) and ensuring breaking through the opening of the moving contact or contacts (17, 29) in the event of excess current, comprising an operating device (5) mounted on a pivot shaft (95), equipped with an actuating lever (5a) and normally forced back into the position of opening of the contacts by a return spring (96), a rocker bar (39), one end of which is mounted on the operating device (5) so as to be off-centre with respect to the said pivot shaft (95), a contact carrier (41) pivoting about a shaft and having a slope (54) against which the other end (39a) of the rocker bar (39) can come to bear and be braced, at least one moving contact (17, 29) being mounted on the pivot shaft of the contact carrier (41) so as to be able to pivot slightly with respect to the latter in order to exert a contact pressure on a fixed contact (20, 35), and a catch (42) pivoting on the contact carrier (41) and intended to lock the end (39a) of the rocker bar in the closed position of the contacts, the catch (42) being associated with a breaking means (43) which is able, when actuated, to cause the catch (42) to tilt and the rocker bar (39) to be released, and, if necessary, to drive the contact carrier (41) into the open position so as to pull away the moving contact (17, 29) by force, the moving contact or contacts (17, 29) being held angularly on the pivot shaft (94) of the contact carrier (41) by an elastic member (76) having a bearing point on the said pivot shaft (94) and at least one bearing point on the moving contact (17 or 29), so as to push the latter, with respect to the said pivot shaft (94), in the direction of the contact pressure on the fixed contact (20, 35), characterised in that the elastic member (76) has at least two bearing points on the moving contact (17 or 29, and 71), the two bearing points acting elastically in opposite directions about the pivot shaft (94), the bearing point tending to close the contacts exerting a greater force than the other bearing point.
2. Lock mechanism according to Claim 1, characterised in that the elastic contact member (76) is a spring of the hairpin type.
3. Lock mechanism according to Claim 1 or 2, characterised in that the catch (42) and the breaking means (43) are made in one piece and pivoted on the pivot shaft of the contact carrier (41).
4. Lock mechanism according to Claim 3, applied to phase and neutral circuit breakers, characterised in that the contact carrier (41) has at least one pivot (56) on which are located the assembly consisting of the catch (42) and the breaking means (43) and at least one moving contact (17, 29) with its elastic contact member (76).
5. Lock mechanism according to Claim 4, characterised in that, opposite the said pivot (56), the contact carrier (41) has a cavity (59) with its median axis aligned with that of the pivot (56) and by which the contact carrier (41) may be located pivotingly on an end of a shaft (94) carried by the casing of the circuit breaker and able to receive the other moving contact (17, 29) and an elastic contact member (76).
6. Lock mechanism according to Claim 5, characterised in that the elastic contact members (76) associated with the two moving contacts (17, 29) are of different strengths.
7. Lock mechanism according to any one of Claims 1 to 6, characterised in that it has a draw spring (50) pulling the contact carrier (41) in the direction of opening of the contacts.
8. Lock mechanism according to any one of Claims 1 to 7, characterised in that the resetting of the catch (42), that is to say its return to the closure position, is provided by the return spring (96) of the operating device (5).
9. Lock mechanism according to any one of Claims 4 to 8, characterised in that the contact carrier (41) is made of moulded plastic and has a cross-head (48) serving as a support for the return spring (50) for the contact carrier (41) and separated from the body of the contact carrier by a V-shaped aperture (51) presenting the said bracing slope (54), and in that the body (55) of the contact carrier (41) has, on its lateral faces, the pivot and the cavity respectively, and on each occasion a pin (64) serving as an articulation for the moving contact and situated closer to the head (48) than the pivot or cavity and, with respect to the latter, opposite the operating device (5).
10. Lock mechanism according to Claim 9, characterised in that the moving contacts (17, 29) are identical and made of metal pieces with a flattened cross section and comprise, in a widened part (68), a main orifice (69), a secondary orifice (70) coming to engage around the said pin (64) and a lateral lug (71) forming a bearing point for the elastic contact member (76), the widened part (68) being extended by an elongate part (72) having the electric contact point and, on the opposite side of the said elongate part (72), a notch (74) forming a second bearing point for the elastic contact member (76).
11. Lock mechanism according to Claim 10, characterised in that the main orifice (69) of the widened part (68) of the moving contacts (29, 17) is oblong.
12. Lock mechanism according to Claim 3, characterised in that the catch (42) and the breaking means (43) are made in one piece from moulded plastic.
13. Circuit breaker characterised in that it has a lock mechanism according to any one of Claims 1 to 12.

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