Circuit breaker case

Claim 2

In a molded case circuit breaker, a case of electrical insulating material divided longitudinally into two approximate half cases, said case enclosing a movable contact and a stationary contact, said movable contact being carried by a pivotal movable arm into and out of engagement with said stationary contact, said case also enclosing an arcing chamber, each half case having a side wall and an end wall together defining three sides of said arcing chamber, said end walls having inner and outer recessed portions together forming a passage extending generally in the direction of travel of the movable contact and for venting said arc gases to one side, one of said end walls including an integral barrier entending therefrom and projecting from said end wall in alignment with the associated side wall, and said passage is inclined transverse to the length of said case and in the direction to vent the arc gases against said barrier.

Claim 3

The circuit breaker recited in claim 1 wherein said end walls also include overlapping portions forming a part of said passage.

Claim 4

The circuit breaker recited in claim 1 and further including grids of magnetizable material inclined at angles generally similar to the angle traversed by the movable contact arm in moving from the contacts closed to the contacts open positions, and said end walls including at least one slot inclined at an angle which intersects the angles of the grids for obstructing entry of a foreign object into the arcing chamber.

Claim 5

In a molded case circuit breaker, a case of electrical inSulating material divided longitudinally through its width into two approximate half cases, said case enclosing a movable contact and a stationary contact, said movable contact being carried by a pivotal movable arm into and out of engagement with said stationary contact, said case also enclosing an arcing chamber and a main chamber, each half case having a side wall, a top wall, a bottom wall and an end wall together defining five sides of said arcing chamber when said half cases are assembled together, an insulator plate defining the sixth side of said arcing chamber, said insulator plate having two margins and a tang therebetween, said insulator plate also having two slots one on each side of said tang and between said tang and one of said margins, said insulator plate also having a space below said tang and intermediate said margins into which said tang may expand when heated, said movable arm having spaced side plates movable through said slots, said half cases including wall means for supporting said insulator plate, and at least one of said margins having a surface in abutment with a portion of said tang for guiding the expansion and contraction of said tang.

Claim 6

In a molded case circuit breaker, a case of electrical inSulating material divided longitudinally through its width into two approximate half cases, said case enclosing a movable contact and a stationary contact, said movable contact being carried by a pivotal movable arm into and out of engagement with said stationary contact, said case also enclosing an arcing chamber and a main chamber, each half case having a side wall, a top wall, a bottom wall and an end wall together defining five sides of said arcing chamber when said half cases are assembled together, an insulator plate defining the sixth side of said arcing chamber, said insulator plate having two margins and a tang therebetween, said insulator plate also having two slots one on each side of said tang and between said tang and one of said margins, said insulator plate also having a space below said tang and intermediate said margins into which said tang may expand when heated, said movable arm having spaced side plates movable through said slots, said half cases including wall means for supporting said insulator plate, and at least one of said margins having a surface in abutment with a portion of said tang for guiding the expansion and contraction of said tang.

Claim 7

The circuit breaker recited in claim 4 wherein said wall means includes a slot to receive a portion of said insulator plate, said tang being free to move within said slot as it expands and contracts.

Claim 8

The circuit breaker recited in claim 4 wherein said insulator plate includes a vertical portion having said tang and an upper portion overlying the arcing chamber and hinged to said vertical portion.

Claim 9

In a molded case circuit breaker, a case of electrical insulating material divided longitudinally into two approximate half cases, said case enclosing a movable contact and a stationary contact, said movable contact being carried by a pivotal movable arm into and out of engagement with said stationary contact, said case also enclosing an arcing chamber, each half case having a side wall and an end wall together defining three sides of said arcing chamber, said end walls having inner and outer overlapping recessed portions together forming a vertical passage which, when viewed in cross section, is sloped transverse to said side walls throughout its length and has a sloped exit opening, defined by a sloped wall, whereby said arc gases are vented, at least in part, across the plane of the nearest side wall.

Claim 10

In a molded case circuit breaker, a case of electrical insulating material divided longitudinally into two approximate half cases, said case enclosing a movable contact and a stationary contact, said movable contact being carried by a pivotal movable arm into and out of engagement with said stationary contact, said case also enclosing an arcing chamber, each half case having a side wall and an end wall together defining three sides of said arcing chamber, said end walls having inner and outer overlapping recessed portions together forming a vertical passage which, when viewed in cross section, is sloped transverse to said side walls throughout its length and has a sloped exit opening, defined by a sloped wall, whereby said arc gases are vented, at least in part, across the plane of the nearest side wall.

Claim 11

The structure recited in claim 7 wherein the inner wall forming said vertical passage has at least one downwardly sloped slot.