| 摘要 |
PURPOSE:To perform prevention of overload under two conditions of a temperature rise of winding and others and an overcurrent by breaking a power supply at an arbitrary temperature with a shape memory alloy. CONSTITUTION:An electric motor turns a tool by rotation of a rotor 2. If an overload is put on said motor and electric current increases, a contact 7 generates heat and said heat is applied to a shape memory alloy 8. If said shape memory alloy 8 is heated to a transformation point, said contact 7 starts coming into touch with the shape memory alloy 8. Accordingly, electric current having flown via the contact 7 is broken and said rotation of the rotor 2 is stopped too. If the shape memory alloy 8 is built in a part influenced by an operating temperature, it operates alike also by temperature rise of winding and others. |
