Nut for ball screw

A nut for a ball screw comprising:

• a nut having an outer surface and a threaded path defined through the nut, and
• multiple dual-narrowed paths located between the threaded path and the outer surface of the nut, the dual-narrowed paths defined through a central axis of the nut and substantially being parallel to the threaded path, each of the dual-narrowed paths having a high-speed area and two low-speed areas, the high-speed area located between the two low-speed areas, a diameter of each of the dual-narrowed paths being reduced from two ends toward the high-speed area;
• multiple micro fans disposed in, the dual-narrowed paths so as to drive air flows in the dual-narrowed paths to reduce temperature;
• a control portion to control operation of the micro fans;
• and
• multiple temperature sensing portions disposed between the threaded path and the outer surface of the nut to sense temperature, the control portion connected with the temperature sensing portions so as to individually control the micro fans.