FR2699730A1 - Miniature circuit breaker with lateral exhaust of the breaking gases. - Google Patents

Abstract

An electrical circuit breaker comprising a molded insulating housing (2) having a rear plinth (4) and two side walls (6) extending forwardly from the rear plinth, said enclosure enclosing a main arc extinguishing chamber. deionization plates producing cut-off gases. The circuit breaker further comprises an elongated gas discharge piece (32) having one end opening into the main chamber and its other open end located at said rear base (4) of the housing (2).

Description

MINIATURE LATERAL EXHAUST CIRCUIT BREAKER

CUTTING GASES

  The present invention relates generally to circuit breakers which are in the form of modular electrical equipment intended to be included in an industrial electrical installation or

  domestic, low voltage or medium voltage.

  The invention relates more particularly to a miniature electric circuit breaker comprising a molded insulating housing, of generally parallelepiped shape, having a rear fixing base, arranged on a rear face of the housing, and two lateral faces extending forwardly at from the rear base, said housing containing a main chamber

  of arc extinction with deionization plates.

  Document FR-A-2 663 458 relates to a

  miniature electric circuit breaker of the type described below

  above In this circuit breaker of the prior art, there is further provided a decompression chamber communicating the output of the main chamber with the external medium, this output being effected through a discharge orifice which is located at the level of the mounting base In addition, in this circuit breaker of the prior art, the decompression chamber comprises a baffle which is located in the vicinity of the discharge orifice This circuit breaker of the prior art has the advantage that the gases from cut out of the circuit breaker housing at its rear base, and therefore, the cut gases are thus diverted to a posterior zone, devoid of live parts under voltage. Thus, this known arrangement improves the reliability of the circuit breaker by reducing the possibilities of electrical priming at the level of the live active parts external to the circuit breaker, in particular at the level of the external terminals and of the electric wires d e connection, because there is generally no active part under voltage arranged at the

  in the vicinity of the rear base of the circuit breaker.

  However, in such a circuit breaker of the prior art, the space available between the main chamber and the rear base is relatively small, in particular, the distance separating the zone through which the gases exit from the main chamber and the evacuation opening made through the rear base is relatively small, for example of the order of 8 to 15 mm On the other hand, this decompression chamber is limited by internal walls whose sum of surfaces remains relatively small The chicane which is provided inside this decompression chamber remains relatively ineffective because it is located in a too small space and because it is too close to the area through

  which gases escape from the main chamber.

  It follows from this that the gases which escape through the evacuation orifice provided in the rear base remain relatively hot and dense, these gases thus being able to create electrical discharges and also being able to prematurely age certain parts of the housing of the circuit breaker, in particular of the parts of the plastic casing situated at the level of the decompression chamber and at or near the evacuation orifice of the rear base. An object of the present invention is to provide a miniature electric circuit breaker in which the gases produced in the main chamber

  arc extinguishers are more effectively decompressed.

  Another object of the invention consists in proposing such a circuit breaker in which there is provided a more efficient decompression chamber, without however

  cause an increase in complexity.

  Another object of the invention consists in proposing such a circuit breaker which can also make it possible to arrange such a decompression chamber which is sufficiently effective to be able to not include

exhaust port.

  Another object of the invention consists in proposing such a circuit breaker in which an outlet orifice for the decompression chamber can be easily formed in a part of the rear base, at a place in this rear base situated at a relatively great distance from the area through which the gases

  escape from the master bedroom.

  The invention therefore relates to an electrical circuit breaker comprising a molded insulating housing having a rear base and two side walls extending forward from the rear base, said housing containing a main arc extinguishing chamber with deionization plates producing cut-off gases According to an essential characteristic of the invention, the circuit breaker further comprises: an opening formed in one of said side walls, opening into said main chamber; an elongated gas evacuation piece, comprising a recess formed longitudinally in a lateral face of the evacuation piece, this recess opening longitudinally only at one of the ends of the evacuation piece, the exhaust having its said side face applied against said side wall of the housing so as to constitute with this side wall an elongated gas evacuation chamber having one closed end and its other end open, said evacuation piece being positioned so that said opening opens into the gas discharge chamber in the vicinity of its closed end and that its other open end is located at said level

rear base of the housing.

  According to a particular embodiment of the invention, the circuit breaker further comprises a cover which has the general shape of a flat plate and which is mounted laterally on said housing parallel to said side wall of the housing, said piece of evacuation being maintained between the cover and the wall

side of the housing.

  According to another embodiment of the invention, said side wall of the housing comprises on its external face of the ribs so that said discharge piece is applied against the side wall of the housing by cooperating with these ribs so that these ribs maintain in position the 'evacuation piece and contribute to the seal between the

  drain piece and housing.

  According to another embodiment of the invention, said gas evacuation chamber has a generally elongated and curved shape in a plane parallel to the plane of the side wall of the housing so that the distance traveled by the gases the

  along the evacuation chamber is increased.

  According to another embodiment of the invention, said gas evacuation chamber has a generally elongated and curved shape in a plane parallel to the plane of the side wall of the housing so that the gases which flow along the chamber evacuation out of the evacuation chamber in an ejection direction substantially perpendicular to the outer face of said rear base

of the housing.

  These and other objects, features and advantages of the present invention will be better

  understood during the detailed description of examples of

  embodiment which follows, illustrated by the appended figures among which: FIG. 1 is a side view of a circuit breaker according to the invention, certain parts and parts of parts being removed in order to show certain internal details of the circuit breaker; Figure 2 is a view similar to that of Figure 1 but in which parts and parts of different parts are removed to show other details of the same circuit breaker according to the invention; Figure 3 is a view similar to that of Figure 2 but in which one of the parts removed in Figure 2 has been returned, in order to show still other details of the same circuit breaker according to the invention; Figure 4 is a partial sectional view along the line IV-IV of Figure 3, in which all parts or parts of parts are present; Figure 5 is a partial sectional view along line V-V of Figure 3, in which all parts or parts of parts are present; and Figure 6 is a view similar to that of Figure 4 but concerning an alternative embodiment of the

circuit breaker according to the invention.

  In FIGS. 1, 2 and 3, the same circuit breaker according to the present invention is shown These three figures differ only in that, from one figure to another, certain parts or parts of parts are removed differently in order to reveal more easily certain internal parts of the device If reference is made to FIGS. 1 and 4, it can be seen that, generally and conventionally, the circuit breaker comprises a housing 2 which has a generally parallelepiped shape and which is generally made of an insulating plastic material The housing 2 comprises a rear base 4 (FIG. 5) which is used * for fixing the circuit breaker and two lateral surfaces 6 (only one is visible in FIGS. 1 to 5), these two lateral surfaces extending forward from the rear base 4 The housing 2 also conventionally comprises an upper wall 8, a lower wall and a front wall 12 The walls 4, 8, 10 and 12 consequently connect the two faces side 6 so as to constitute the general parallelepiped shape of the housing 2 The housing 2 contains the whole of the conventional mechanism of the circuit breaker and in particular it contains a main arc extinguishing chamber 14 (FIG. 1) which comprises a number of deionization plates 16 arranged between two conductive elements 18 and 20 On the side wall 6 is formed an opening 22 (FIG. 2) which opens into the main chamber 14 and which makes it possible to evacuate the cutting gases through this opening 22 Consequently, the cut-off gases generated in the main chamber 14 are evacuated laterally through

  the opening 22 formed in the side wall 6.

  The housing 2 also comprises, at the side face 6, a raised periphery 24 which extends radially outward from the side wall 6 and whose external edge 26 is adapted

  to conventionally receive a side cover 28.

  Consequently, when the cover 28 is mounted against the rim 26, the assembly constitutes a lateral space 30 which is substantially closed and which extends between the side wall 6 and the cover 28 according to a relatively small thickness, for example between 3 and 8 mm. As can be seen in Figures 3, 4 and 5, in the lateral space 30, is arranged a part

  gas exhaust 32 which is described in detail above

  after The gas discharge part 32 has a general shape of a chute, that is to say that, as can be seen in the sectional view of Figure 5, this part 32 has a section which is in the shape of an inverted U, this over its entire length The gas discharge part 32 thus has an elongated shape which extends from an area located above the opening 22 to an area located at the level of the external face of the rear base 4, as can be seen in

particular in Figure 3.

  As can be seen in FIG. 5, the gas evacuation piece 32 is applied against the external face of the side wall 6 of the housing 2, so that its internal hollow part constitutes with the side wall 6 a chamber 34 which is called hereinafter "expansion chamber" because this chamber 34 is intended to relax the cut-off gases which are produced in the main chamber 14 of the circuit breaker and which pass into the expansion chamber 34 through the opening 22 These cut-off gases therefore enter the expansion chamber 34 at the opening 22 and move along this chamber to its open end 36 which is located at the external face of the rear base 4 of the housing 2 Consequently, the breaking gases exit from the circuit breaker at the rear base 4 of the latter, like this

  is represented by the arrow in figure 3.

  In Figure 2, we can see in top view the circuit breaker in which we see the side wall 6 of the housing 2 but in which the gas discharge part 32 has been removed Arrows in Figure 2 indicate the path of the gases cutoff from their outlet at the level of the window 22 to the outlet 36 of the expansion chamber 34 The gas discharge part 32 is fixed in a relatively leaktight manner on the side wall 6 by means of ribs 38, 40 which are provided in protuberances on the external face of the side wall 6 and which allow an interlocking of the gas discharge part 32 on these ribs These ribs 38, 40 further ensure positioning of the discharge part 32 as well as an improvement in the seal between the discharge piece 32 and the side wall 6 of the housing 2 Furthermore, as can be seen in FIGS. 3 and 5, the gas discharge piece 32 comprises, in a way classic in itself, fixing lugs 42, 44, 46 which each include a hole through which passes a

  stud 48 formed in protrusion on the side wall 6.

  In other words, it can be said that the gas discharge piece 32 is of elongated shape, comprising a recess 34 formed longitudinally in a lateral face 50 of the discharge piece, this recess 34 opening longitudinally only at level d one of the ends 36 of the evacuation piece, the evacuation piece having its said side face 50 applied against said side wall 6 of the housing 2 so as to constitute with this side wall 6 a gas evacuation chamber 34 elongated having a closed end 52 and its other open end 36, said discharge piece 32 being positioned so that said opening 22 opens into the gas discharge chamber 34 in the vicinity of its closed end 52 (FIG. 4) and that its other open end 36 (Figure 3) is located

  at said rear base 4 of the housing 2.

  The cover 28 has the general shape of a flat plate and is mounted laterally on said housing parallel to said side wall of the housing, said discharge piece 32 being held between the

  cover 28 and the side wall 6 of the housing 2.

  Preferably, as can be seen in FIG. 3, the gas evacuation chamber 34 has a generally elongated and curved shape or provided with elbows 54, 56 while remaining in a plane parallel to the plane of the side wall 6 of the housing 2 so that the distance traveled by the gases along the evacuation chamber is increased On the other hand, this curvature or these elbows of the evacuation chamber 34 ensures that the gases which flow along the evacuation chamber leave the evacuation chamber in an ejection direction substantially perpendicular to the external face of said rear base 4

  of housing 2 (arrow in Figure 3).

  The evacuation chamber 34 has a relatively flattened shape, that is to say that the thickness of this chamber measured in a direction perpendicular to the side wall 6 is small (for example 1 to 4 mm) relative to the width of the chamber measured in a direction parallel to the side wall 6 (for example 7 to 15 mm) and to its length measured also in a direction parallel to the side wall 6 (for example 30 to 80 mm) This flat shape ensures a efficient cooling of the gases without excessive local heating of certain parts of the circuit breaker On the other hand, this gas evacuation chamber 34 is advantageously housed in

  a part of the circuit breaker which is otherwise unused.

  Preferably, the housing 2, the gas discharge part 32 and the cover 28 are produced

  made of insulating molded plastic.

Claims (4)

  1 electrical circuit breaker comprising a molded insulating housing (2) having a rear base (4) and two side walls (6) extending forward from the rear base, said housing containing a main arc extinguishing chamber (14) with deionization sheets (16) producing cutting gases, characterized in that it further comprises: an opening (22) formed in one of said side walls (6), opening into said main chamber (14 ); a gas discharge piece (32) of elongated shape, comprising a recess (34) formed longitudinally in a lateral face (50) of the discharge piece, this recess opening longitudinally only at one of the ends (36 ) of the discharge piece, the discharge piece (32) having its said side face (50) applied against said side wall (6) of the housing (2) so as to constitute with this side wall a elongated gas discharge (34) having one closed end (52) and its other open end (36), said discharge piece (32) being positioned so that said opening (22) opens into the discharge chamber gas (34) in the vicinity of its closed end (52) and that its other open end (36) is located at said rear base (4) of the housing (2).   2 electrical circuit breaker according to claim 1, characterized in that it further comprises a cover (28) which has a general shape of a flat plate and which is mounted laterally on said housing (2) parallel to said side wall (6) of the housing, said discharge piece (32) being held between the cover and the side wall of the housing. 3 Electric circuit breaker according to one of   previous claims, characterized in that   said side wall (6) of the housing comprises on its external face ribs (38, 40) so that said discharge piece (32) is applied against the side wall (6) of the housing by cooperating with these ribs (38 , 40) so that these ribs hold the discharge piece in position and contribute to   the seal between the discharge piece and the housing.   4 Electric circuit breaker according to one of   previous claims, characterized in that   said gas discharge chamber (34) has a generally elongated and curved shape (54, 56) in a plane parallel to the plane of the side wall of the housing so that the distance traveled by the gases along   the evacuation chamber be increased.   Electric circuit breaker according to one of   previous claims, characterized in that   said gas discharge chamber (34) has a generally elongated and curved shape (54, 56) in a plane parallel to the plane of the side wall of the housing so that the gases which flow along the discharge chamber exit the evacuation chamber in an ejection direction substantially perpendicular to   the outer face of said rear base (4) of the housing (2).