| 摘要 |
PURPOSE:To enhance cooling efficiency, by constituting the title apparatus so that cooling air is blown to a normal use electromagnet until a non-normal use electromagnet reaches dangerous temp. and an air blow passage is altered when the non-normal use electromagnet reaches the dangerous temp. to blow cooling air to the non-normal use electromagnet. CONSTITUTION:When only a non-normal use electromagnet is used, the non-normal use electromagnet is at ambient temp. and a butterfly valve 11 is revolved by the elasticity of a return spring 13 to change over an air blow passage so as to blow cooling air only to a normal use electromagnet. When the non-normal use electromagnet is used, the non-normal use electromagnet rises in its temp. and, when the temp. thereof reaches dangerous temp., the elasticity of a shape memory alloy spring 12 becomes stronger than that of the return spring 13 and the valve 11 is reversely revolved to change over the air blow passage so as to be capable of blowing cooling air to all of electromagnets. When the temp. of the non-normal use electromagnet falls, the return valve 11 is again revolved by the return spring to form the air blow passage so as to blow cooling air to the non-normal use electromagnet. By this method, cooling air is selectively blown to the electromagnet to be cooled and cooling efficiency can be enhanced. |
