Patent ID: 6538549
Filing Date: 2003-03-25
Classification: H01H

Abstract:
An electrical circuit breaker for protecting an electrical circuit, the electrical circuit breaker comprising:a housing; first and second electrical terminals affixed to the housing, the first and second electrical terminals configured to electrically couple the electrical circuit breaker to the electrical circuit; a contact arm including first and second portions, the first portion electrically coupled to the first terminal and rotatably mounted within the housing, and the second portion having an arm contact affixed and electrically coupled thereto; a cam including first and second portions, the first portion rotatably mounted within the housing, the second portion movably coupled to the contact arm such that rotation of the cam in a first rotational direction through a first amount of rotation causes rotation of the contact arm in a second rotational direction and further rotation of the cam in the first rotational direction through a second amount of rotation beyond the first amount of rotation causes rotation of the contact arm in a direction counter to the second rotational direction; a torque generating member configured to apply a torque to the cam tending to rotate the cam in the first rotational direction; and a bimetal blade electrically coupled to the second electrical terminal, the bimetal blade configured to change shape based upon an amount of electrical current above a threshold level for at least a predetermined amount of time passing through the bimetal blade, the bimetal blade having a blade contact affixed and electrically coupled thereto, the bimetal blade shaped and positioned with respect to the contact arm such that the blade contact contacts the arm contact to prevent the contact arm from rotating in the second rotational direction when the amount of electrical current flowing through the bimetal blade is below the threshold level, the bimetal blade shaped and positioned with respect to the contact arm to allow the contact arm to rotate in the second rotational direction with the cam rotating in the first rotational direction through the first amount of rotation and to allow the arm contact to remain in contact with the blade contact when the amount of electrical current flowing through the bimetal blade increasingly exceeds the threshold level by up to a first amount of electrical current for at least a predetermined amount of time.