Molded-case electric circuit breaker with contact arm latch

Claim 2

In an electric circuit breaker having a pivotable contact arm structure movable between an open position and a closed position, a toggle mechanism including a pivotable cradle movable between a set position and a tripped position, a collapsible toggle joint movable between a collapsed position and a straightened position for actuating the contact arm structure between the open and closed positions, respectively, when the cradle is in its set position, a manual operating mechanism movable between an OFF position and an ON position and including a means to move the cradle from its tripped position to its set position as the manual operating mechanism is moved to the OFF position, and an overcenter spring-biasing means connected between the manual operating mechanism and the toggle joint for actuating the toggle joint between the collapsed and straightened positions when the manual operating mechanism is moved substantially to the OFF and ON positions, respectively, the improvement comprising releasable complementary interlock means on the contact arm structure and cradle, respectively, effective when the cradle is in the set position and the manual operating mechanism is in the OFF position to prevent movement of the contact arm structure to its closed position until the biasing means is substantially beyond its overcenter position and in a state of increased tension as a resulT of movement of the manual operating mechanism substantially to the ON position, and interlock defeating means on said manual operating mechanism for defeating the interlock means upon further movement of the manual operating mechanism toward the ON position, whereby the toggle joint straightens under the force of the increased tension of the biasing means to drive the contact arm structure to its closed position, the interlock means comprising a contact arm latch fixedly secured to the contact arm structure and a complementary latching shoulder on the cradle and positioned adjacent the contact arm latch when the contact arm structure is in its open position, and the contact arm latch including a latching surface latched with the latching shoulder on the cradle when the cradle is in its set position and the contact arm structure is in its open position.

Claim 3

A circuit breaker as claimed in claim 1 wherein the contact arm latch comprises a resilient member extending outwardly from the contact arm structure and including said latching surface.

Claim 4

An electric circuit breaker as claimed in claim 2 wherein the interlock defeating means on the manual operating mechanism includes a roller which travels in an arcuate path determined by pivotable movement of the manual operating mechanism, the contact arm latch lies in the arcuate path when the contact arm structure is in said open position so that, upon movement of said manual operating mechanism toward ON position, the roller engages the contact arm latch to force the latching surface out of latching engagement with the complementary latching shoulder on the cradle thereby to defeat the releasable interlock means.

Claim 5

An electric circuit breaker as claimed in claim 3 wherein the contact arm latch is generally L-shaped and has a base portion secured to said contact arm structure.

Claim 6

An electric circuit breaker as claimed in claim 4 wherein the portion of the contact arm latch extending outwardly from the contact arm structure has a laterally extending portion an edge of which defines the latching surface.

Claim 7

In a circuit breaker having an elongated contact arm structure pivotable about one end portion in one direction to an open position and in an opposite direction to a closed position, a toggle mechanism including a releasably latchable cradle pivotable about one end portion in one direction to a set position and in an opposite direction to a tripped position, said toggle mechanism also including a collapsible toggle joint movable to a collapsed position and to a straightened position for driving the contact arm structure to the open and closed positions, respectively, a manual operating mechanism pivotable in one direction to an OFF position and in an opposite direction to an ON position, means for pivoting the cradle from its tripped position to its set position when the manual operating mechanism is moved substantially to the OFF position, and an overcenter spring biasing means connected between the manual operating mechanism and the toggle joint for driving the toggle joint to the collapsed position when the spring biasing means is moved to a first overcenter position with respect to the toggle joint in response to the movement of the manual operating mechanism substantially to the OFF position and for driving the toggle joint to the straightened position when the spring biasing means is moved to a second overcenter position with respect to the toggle joint in response to the movement of the manual operating mechanism substantially to the ON position, the improvement comprising a contact arm latch fixedly secured to the contact arm structure generally intermediately thereof, said contact arm latch having a latching surface spaced above and facing toward the contact arm structure, a latching shoulder on an end portion of the cradle positioned adjacent the contact arm latch when the contact arm structure is in its open position, said latching shoulder portion facing away from the contact aRm structure and engaging the latching surface on the contact arm latch when the cradle is in the set position and the contact arm structure is in its open position, thereby preventing movement of the contact arm structure to its closed position until the spring-biasing means is substantially beyond its second overcenter position and in a state of increased tension as a result of movement of the manual operating mechanism substantially to the ON position, and means on the manual operating mechanism for mechanically driving the contact arm latch out of engagement with the cradle thereby to effect movement of the contact arm structure to the closed position.

Claim 8

In a circuit breaker having an elongated contact arm structure pivotable about one end portion in one direction to an open position and in an opposite direction to a closed position, a toggle mechanism including a releasably latchable cradle pivotable about one end portion in one direction to a set position and in an opposite direction to a tripped position, said toggle mechanism also including a collapsible toggle joint movable to a collapsed position and to a straightened position for driving the contact arm structure to the open and closed positions, respectively, a manual operating mechanism pivotable in one direction to an OFF position and in an opposite direction to an ON position, means for pivoting the cradle from its tripped position to its set position when the manual operating mechanism is moved substantially to the OFF position, and an overcenter spring biasing means connected between the manual operating mechanism and the toggle joint for driving the toggle joint to the collapsed position when the spring biasing means is moved to a first overcenter position with respect to the toggle joint in response to the movement of the manual operating mechanism substantially to the OFF position and for driving the toggle joint to the straightened position when the spring biasing means is moved to a second overcenter position with respect to the toggle joint in response to the movement of the manual operating mechanism substantially to the ON position, the improvement comprising a contact arm latch fixedly secured to the contact arm structure generally intermediately thereof, said contact arm latch having a latching surface spaced above and facing toward the contact arm structure, a latching shoulder on an end portion of the cradle positioned adjacent the contact arm latch when the contact arm structure is in its open position, said latching shoulder portion facing away from the contact aRm structure and engaging the latching surface on the contact arm latch when the cradle is in the set position and the contact arm structure is in its open position, thereby preventing movement of the contact arm structure to its closed position until the spring-biasing means is substantially beyond its second overcenter position and in a state of increased tension as a result of movement of the manual operating mechanism substantially to the ON position, and means on the manual operating mechanism for mechanically driving the contact arm latch out of engagement with the cradle thereby to effect movement of the contact arm structure to the closed position.