EP0020312A1

EP0020312A1 - Single-pole circuit breaker

Info

Publication number: EP0020312A1
Application number: EP80830032A
Authority: EP
Inventors: Aldo Vescovi; Francesco Cravino
Original assignee: Bassani SpA; Bassani Ticino SpA
Current assignee: Bassani SpA; Bassani Ticino SpA
Priority date: 1979-06-01
Filing date: 1980-05-27
Publication date: 1980-12-10
Also published as: IT1121759B; ATE2982T1; IT7923210A0; DE3062602D1; EP0020312B1; ES489020A0; MX148216A; ES8103466A1; BR8002196A

Abstract

The present invention relates to a single-pole circuit breaker, wherein the mechanic components of the snap mechanism, such as the manual operating member (8), the latching cradle (12) and the movable contact carrier (29) have a flattened shape so that they are assembled in a superimposed position thus allowing the reduction of the size of the circuit breaker, all said components being shaped such in a way that they may be easily produced by simple blanking, without requiring further machinings and still assuring the best intervention chances particularly in overload or short circuit current conditions.

Description

This invention relates to a sinqle-pole circuit breaker.
Single-pole circuit breakers are already known and are employed for protecting single phases of an electrical circuit against overload and short circuit current conditions.
According to the known art said single-pole circuit breakers are installed one by one, or juxtaposed in a certain number, and interconnected so that the manual operation takes place simultaneously for all the circuit breakers as well as the automatic operation takes place simultaneous ly for all the juxtaposed circuit breakers, even when it occours an anomalous current condition in a single phase of the electric circuit.
Said known circuit breakers are provided with a snap mechan ism comprising a manual operating member, a movable contact carrier, having one end fulcremed on said manual operating member and supporting on the other end the movable contact of the single pole circuit breaker, and a latchinq or set cradle for the automatic opening, said latching cradle being pivoted at one end on a stationary pin and having, at the other end, a tip designed to be latched to the latch aperture or notch of a trip lamina, said trip lamina being designed to disengage said latching cradle when an overload or a short circuit current condition occurs, a spring being interconnected between said movable contact carrier and said manual operating member, or between said movable cont act carrier and said latching cradle,and being designed to cooperate with the above mentioned members to define an over-center articulation for snapping the mechanism towards the open or close position and to supply the contact pressure between the movable and the stationary contacts.
The single-pole circuit breakers so conceived, are installed in a great number both in home and in industrial electric wirings and are juxtaposed on suitable supports. Conseguently, the problem of the mass production of said single-pole circuit breakers and at low cost, as well as the problem of the diminution of their size even though the must assure the required intervention characteristic,arise.
The object of the present invention is to provide a single pole circuit breaker of the kind hereinbefore described that can be produced in a high series and that can be mechanically assembled so that, the labour may be reduced, furthermore a single-pole circuit breaker the mechanic components of which are designed and shaped such in a way that they may be easily produced only by simple blanking, without reguiring further machinings, and that are interconnected to contribute to the reduction of the encumbran ce of the circuit breaker still assuring the best interven tion chances, particularly, in the event of short-circuit current, assuring a sudden opening which cannot be obtained by the similar single-pole circuit breaker of the prior art.
The single-pole circuit breaker according to the present invention is characterized by a manual operating member havinq a flattened shape of reduced thickness, parallel to the flat walls of the moulded case and being outlined as a circular sector and having its apex shaped as a fork pivot ed on a fixed pin not projecting from the thickness of said circular sector, by a latching cradle having a flattened shape as well and being pivoted such in a way that it may be superimposed and it may run over said manual operating member, said latching cradle carrying in its middle port ion a pin projecting in the direction away from the manual operating member, by a movable contact carrier having a portion remote form the movable contact which is also flattened and is provided with an end shaped as a fork, pivoted on the pin carried by the latching cradle, so that said manual operating member, said latching cradle and said movable contact carriar are partially superimposed one with respect to the other in the direction of the thickness of the moulded case, the whole encumbrance being therefore reduced, said single-pole circuit breaker being also characterized by an over-center snapping spring con nected between said movable contact carrier and said man ual operating member in respective engaging points compris ind, therebetween both the pivoting pin of said manual oper ating member and the pivoting pin of said movable contact carrier.
According to a preferred embodiment of the invention, the single-pole circuit breaker is characterized by a relief provided on a side of sai.d manual operating member, projec ting from the surface thereof facing the latching cradle and by an appendix projecting outwards said latching cradle said appendix generating a recess with the outer edge of the latching cradle, said recess being engaged by said relief to limit the tripping movement of the latching crad le when an automatic opening takes place, the engagement and the runninq of said relief along the edge of said append ix serving to drive said latching cradle in the latched pos ition when the manual operating member is operated to reset the circuit breaker.
According to a further embodirent of the invention, the single-pole circuit breaker, s characterized by the fact that the movable contact carrier is provided with an ending portion, carrying the movable contact, having an arcuate shape, with the convex edge remote from the stationary contact, said convex edge ending with a projecting straigth edge, while a shoulder rising from the wall of the moulded case is provided opposite said convex edge, so that, in condition of manual opening, said convex edge abuts against said shoulder, while, in condition of automatic opening, said straigth edge abuts against the shoulder because of a composite movement due to the movement of the movable cont act carrier around its pivoting pin and to the movement of the latching cradie so that, in the latter condition, the spacement between the stationary and the movable contacts is increased.
According to a further embodiment of the invention,the single-pole circuit breaker is characterized by the fact that said arcuate portion of the movable contact carrier is provided with an inner end projecting towards the pivot ing pin of the latching cradle while the nearer end of the latching cradle is provided with a projection designed to interfere with said inner end of the arcuate portion during the automatic opening and in the event the fixed and the movable contacts get welded together, said interference caus ing the detachement of the movable contact and avoiding the rebound of the latter towards the stationary contact.
An embodiment of the invention by way of example will be pointed out more fully hereinafter with reference to the accompanying drawings, wherein:

Figure 1 is a front view of the sinqle-pole circuit breaker in closed condition and having removed the upper shell of the case.
Figure 2 shows the circuit breaker of fiq. 1 in condit ion of manual opening;
Figure 3 shows the same circuit breaker in condition of automatic opening;
Figure 4 shows the circuit breaker in an intermediate condition of the automatic opening step;
Figure 5 is a side view of the moulded case of the single-pole circuit t breaker of figg. from 1 to 4.

Referring to said figures the single-pole circuit breaker, according to the present invention, is contained in a moul ded case composed by a bottom she11 1 and a covering shell 2 coupling along an edge 3, the covering shell 2 having a depth lesser that the depth of the bottom shell 1 and being removed in fig. 1-2-3-4.
Said moulded case, according to the known art, is produced by moulding shells 1 and 2, preferably in a insulating mat erial that cannot be deformed in condition of overheating and cannot be scored by the sparkinq of the contacts, such as dicyanamide or aldehyde resins and the like.
The bottom shell 1 shows a peripheral wall 4 higher than the wall of the covering shell 2 and is provided with a bottom wall 5 from which pins, ribs or seats project and that are obtained by being moulded integral with the bot tom shell and that will be recited from time to time in the specification.
The moulded case on one of its sides is provided with an opening 6 through which the handle 7 of the manual operat- inq member 8 does pass, the latter having a flattened shape of reduced thickness and outlined as a circular sector.
The arcuate edge of the operating member 8 is limited by an arcuate wall 9 the arc amplitude of which does close the opening 6 in every position of the manual operating member
Said manual operating member 8 is provided at it apex with a fork 10, having an arcuate bottom and engaging a pin 11 rising from the bottom wall 5, so that the manual operating member 8 may swing around the pin 11 and may be easily mounted mechanically, thus avoiding the centering problems.
Over the flattened portion of the manual operating member 8, a latching cradle 12 runs, said latching cradle having an end 13 provided with a hole through which it may be pivoted on a pin 14 projecting from the bottom wall 5. The same end 13 is provided with a projection 15 designed to constitute a thrust member for the movable contact carrier in a way that will be specified hereinafter.
The other end 16 of the latching cradle 12 ends with a tip 17 designed to be latched on the upper edge of an opening 18 provided on a trip lamina 19.
Said trip lamina 19 has its upper end accomodated in a seat 20 provided at the peripheral portion of the bottom shell 1.
At the other end 21 said trip lamina 19 is connected to a bimetallic lamina 23 by means of a calibration screw 22, the head of the latter being accessible through an opening 22'.
The trip lamina 19, near its and 21 holds up a movable armature 24 of magnetizable iron, which has the shape of a plate of proper thikness.
this arrangement allows the tripping i of the tip 17 by displacement of the trip 1 amina 19 either in the event of an overload current that by heating the bimetallic lamina 23, causes the bending of the 1 alter and the pulling of the trip lamina 19, or in the event of a short circuit current that causes the sudden attraction of the armature 24 towards the bimetallic lamina 23.
The bimetallic lamina 23, in turn, is electrically connected to a terminal 25, to which an external conductor is fixed, the connection beinq realized throught a riqid conductor 26 having one of its ends connected to the upper end 27 of the bimetallic lamina.
The other end 28 of the bimetallic lamina 23 is electrically connected to a movable contact carrier 29 through a flexible conductor 30.
The latchinq cradle 12, in its middle portion, is provided with an appendix 31 projecting outward, said appendix def- ininq a recess 32 with the outer edge of the same latching cradle.
A relief 33 projects near the edge of the manual operating member 8 end from the surface facing the latching cradle 12, said relief being shaped as a circular sector and being designed to interfere with the appendix 31 and the recess 32 alternaatively in a way that will be descrihed hereinafter.
An arm 34 is provided after the arcuate portion of the mov able contact carrier 29, said arm 34 having the distal end shaped as a fork 35 the bottom of said fork being arc uated, so that the fork may be pivotable on a pin 36 prov ided in the middle portion of the latching cradle 12.
The movable contact carrier 29 carries a movable contact 37 designed to get in touch with a stationary contact 38, carried by a stationary contact carrier 39 integral with a terminal 40 to a which a second exterior conductor is fixed.
The movable contact carrier 29 can be of the kind carrying two juxtaposed movable contacts designed to touch two corresponding stationary contacts according to the known art.
An arcuate spring 41 is connected between the manual oper- atinq member 8 and the movable contact carrier 29 and its function is to bias the movable contact carrier towards the manual operating member 8.
Said arcuate spring 41 is constituted by a spring steel bar and is bent at its upper end, as to provide a pivoting pin in a hole 42 of the manual operating member 8 and it is also ben at its lower end to provide a pivotinq pin in a hole 43 of the movable contact carrier 29.
From the arrangement above discussed it may be seen that the manual operating member 8, the latching cradle 12 and the arm 34 of the movable contact carrier 29 are all Flattened members of reduced thikness so that they do not reg uire specific machinings, therefore they may be produced at a low cost. Moreover, said members are partially oven apped one on top of the other, the encumbrance of the whole over-center snapping mechanish being reduced with respect to the mechanisms of the known art. It is also evident that said members, comprising the arcuate spring 41, are connec ted such in a way that the may be easily assembled mechanically without relevant centering problems of the pins.
Purthemore is has to be noted that the pivoting pin 11 of the manual operating member 8 and the pivoting pin 36 of the movable contact carrier 29 are disposed between the ending pins of the arcuate sprinq 41 so that in the closed position they are both on one side of the line passing through the ending pins of the spring 41while in the open position, both automatic and manual, they are disposed on the opposite side of said line.
Moreover, this arrangement supplies a bias to the latching cradle 12, said bias at the tripping moment makes the latching cradle move upward, i.e. towards the manual operating member 8.
The upward movement of the latching cradle 12 had already been obtained by some of the prior art circuit breakers, but the latching cradle, the movable contact carrier and the manual operating member required a complex construction, said complex construction not allowing the mechanical assembly, as it may be noted in the single-pole circuit breaker disclosed in the U.S. Patent n. 3.818.168.
The operation of the single-poie circuit breaker of the invention will be specified with reference to figures 2, 3
Fig. 2 shows the circuit t breaker in the manually open condition reached by moving the manual operating member 8 by means of the handle 7.
The swinging of the manual operating member H causes the displacement of the hole 42 so that as soon as the line joinig holes 42 and 43 has passed over the pin 36, corresponding to the over-center position, the movable contact carrier snaps in the open position rotating around said pin 36 that remains stationary with the latching cradle 12.
The convex edge of the arcuate portion of the movable cont act carrier 29 interferes with a shoulder 44 provided by a web rising from the bottom wall 5, as to limit the opening path of the contact 37 with respect to the stationary contacts 38.
Fig. 3 shows the single pole circuit breaker in the automat ic open condition, as a consequence of an overload or of short circuit current. In this case the latching cradle 12 is released by the trip lamina 19 and, because of the bias exerced by the movable contact carrier 29, it rotates upward i.e. towards the handle 7.
The pin 36 is conseguently dispidced from the right side on the line connecting holes 42 and 43 (fiq.1) to the left side of said line (fig.3) causing the snap opening of the movable contact carrier 29 as soon as it passes beyond the over center (fiq.3).
In this event the movable contact carrier not only does rotate aruound the pin 36, but it follows the upward displac ement of said pin.
Consequently, the straight portion 34' of the arcuate edge abuts against the shoulder 44 obtaining a width of the spacement between the stationary and the movable contacts greater that the spacement obtained with the manual operation.
in said automatic open position, the spring 41 has caused the displacement of the manual operating member 8 to an intermediate position, as shown in fiq.3, said intermediate position being determined by the interference of the relief 33 with the recess 32.
The reset of the circuit breaker from the automatic open position of fig.3 takes place as follows.
The handle 7 of the manual operating member 8 is initially displaced toward the right side (i.e. towards the manual open position), consequently the latching cradle 12 moves because of the interference betweer the relief 33 and the recess 32 until the tip 17 or the latching cradle 12 is engaged by the hole 18 of the trip lamina 19, reaching the position of fiq.2,
Durinq this displacement, the relief 33 runs along the closed edge of the appendix 31 and the movable contact carrier 29 is moved for positioning its convex edge against the shoulder 33.
At this moment the circuit t breaker may be operated in the "on" position displacing the manual operating member 8 towards its closed position, reaching the condition of fig.1.
Fig.4 is related to a condition that may occur in case of automatic opening.
In effect, it may occur that the movable and stationary contacts 37 - 38, may become stuck togheter because of the welding of the materials,otherwise it may occur that the movable contact carrier 29, after an initial opening movement, tends to return towards the stationary contact.
The projection 15, carried by the end 13 of the latching cradle 12, has the aim to cause the detachement of the movable contact 37 from the stationary contact 38 and the return stroke of the movable contact carrier to the close position.
In effect after the tripping of the latching cradle 12 and during its rotation. if the movable contact 37 is welded to the stationary contact 38, the projection 15 interferences wich the projecting end 29', causing the detachement of the movable contact.
On the other end, if the movable contact carrier 29,once it is, detached is caused to return toward the closed position, it will in any case meet the projection 15 and will be prevented to return to said closed position.
This description is made only by way of example and not as a limitation to the scope of the invention, many variations and modifications may be made and will become appar ent to those skilled in the art; said modification and variations fall within the true spirit and scope of the invention as pointed out by the appended claims.

Claims

1. Single-pole circuit breaker of the kind comprising a moulded case (1), an over-center snap mechanism composed by a manual operating member (8) swinging around a respective fixed pin (16) by a hatching cradle (12) having one end inged on a pivoting pin (14) fixed to the moulded case (1) and the other end provided with a tip (17) designed to engage a trip lamina (19) able to trip said tip (17) in over-load or short current conditions, by a movable contact carrier (29) designed to move in "ON" or "OFF" position a movable contact (37) with respect to a stationary contact (38) and by a pulling spring (41) having one end engaged to said movable contact carrier (29) and the other end engaged to the manual operating member (8) or to the latching cradle (12) provided to cooperate with the engaged members to perform an over-center mechanism for supporting in "ON" and "OFF" position said movable contact carrier (29) and to supply the contact pressure between the stationary and the movable contacts, characterized in that said manual operating member (8) has a flattened shape of reduced thickness, parallel to the flat walls of the moul ded case and is outlined as a circular sector and has its apex shaped as a fork (10) pivoted on a fixed pin (11) not protecting from the thickness of said circular sector; by a latching cradle (12) having a flattened shape and being pivoted such in a way that it may be superimposed and it may run over said manual operating member (8); said latching cradle (12) carrying in its middle portion a pin (36) projecting in the direction away from the manual oper ating member (8) , by a movable contact carrier (29) having a portion (34) remote From the movable contact (37) which is also flattened and is provided with an end shaped as a fork, pivoted on the pin (36) carried by the latching cradle, so that said manual operating member (8) said latching cradle (12) and said movable contact carrier (29) are part- tially superimposed one with respect to the other in the direction of the thickness of the moulded case (1), the whole encumbrance being therefore reduced, said sinqle-pole circuit breaker being also characterized by an over-cen ter snapping spring (41) connected between said movable contact carrier (29) and said manual operating member (8) in respective engaging points (42-43) comprising therebet ween, both the pivoting pin (11) of said manual operating member (8) and the pivoting pin (36) of said movable contact carrier (29).

2. Single-pole circuit breaker according to claim 1 characterized in that a relief (33) is provided on a side of said manual operating member (8) projecting from the surface thereof and facing the latching cradle (12) and by an appen dix (31) projecting outward said latching cradle, said appen dix (31) generating a recess with the outer edge of the latching cradle (12), said recess being engaged by said relief thus limiting the tripping movement of the latching cradle (12) when an automatic opening takes place, the engagement and the running of said relief (33) along the edge of said appendix (31) serving to drive said latching cradle (12) in the latched position when the manual operating member (8) is operated ro resed the circuit breaker.

3. Single-pole circuit breaker according to claims 1 and 2 characterized in that the stationary contact carrier, in the automatic open position, spaces the movable contact(37) From the stationary contact (38) and characterized by the fact that a movable contact carrier (29) is provided with an ending portion carrying the movable contact (37) having an arcuate shape, with the convex edge remote from the sta tionary contact, said convex edge ending with a projecting straight edge (34') while a shoulder (44) rising from the wall of the moulded case is provided opposite said convex edge, so that in condition of manual opening said convex edge abuts against said shoulder, while in condition of automatic opening said straight edge (34') abuts against the shoulder because of a composite movement due to the movement of the movable contact carrier around its pivotinq pin (36) and to the movement of the latching cradle, so that the latter condition the spacement between the station ary and the movable contacts is increased.

4. Single-pole circuit breaker according to claims 1 and 3, characterized by the fact that said arcuate portion of the movable contact carrier is provided with an inner end (29') projecting towards the pivoting pin (14) of the latching cradle while the nearer end of the latching cradle is provided with a projection (15) designed to interfere with said inner end (29') of the arcuate portion during the automatic opening and in event the fixed and the movable contacts get welded together, said interference causing the detachement of the movable contact and avoiding the rebound of the latter towards the stationary contacts.