Patent ID: 8154375

Claim:
An overcurrent protection device having a trip free mechanism, the overcurrent protection device comprising: a housing; a button fitting inside an inner periphery of an opening of the housing, and having a receiving space formed therein and corresponding to a bottom end thereof, wherein the receiving space has an extended rod received therein, and the extended rod has a top end connected to the button; an elastic element sleeved on the extended rod, and having a top end abutting against the button and a bottom end abutting against a stopping block formed on an inner wall of the housing; a first wire terminal mounted in the housing, and having a first end protruding out of the housing; a memory alloy plate having a first end connected to a second end of the first wire terminal, and a free end having a first contact at a position between the first end and a second end of the memory alloy plate, wherein the first contact is aligned with the extended rod, and wherein when the free end is forced by an external force to overcome a critical deformation stress of the free end, the free end is triggered to deform, and when the temperature of the memory alloy plate is over a predetermined temperature due to an overload of a current passing through the memory alloy plate, the free end returns to an original status prior to deformation based on a thermal memory effect; a second wire terminal mounted in the housing, and having a first end protruding out of the housing and a second end provided with a second contact aligned with the first contact; and an elastic metal sheet having a first end movably connected to a position of the memory alloy plate close to the first end thereof, and a second end movably connected to an end edge of the free end of the memory alloy plate, wherein when a top surface of the button is pressed, a bottom end of the extended rod pushes the first contact, so that the free end is shifted to overcome a critical deformation stress of the free end for triggering the free end to deform, and the first contact contacts the second contact, while the first wire terminal is electrically connected to the second wire terminal, wherein the elastic element is compressed between the button and the stopping block, so that an elastic force accumulated by the compression of the elastic element is released when the button is released, and the button is shifted away from the first contact to separate the bottom end of the extended rod from the first contact and to provide a space for the free end to return the original status prior to deformation of the memory alloy plate, such that the free end returns to the original status prior to deformation based on the thermal memory effect to separate the first contact from the second contact when the temperature of the memory alloy plate is over the predetermined temperature due to the overload of the current passing through the memory alloy plate.