Design of the ball screw-driven elevator for use in the building industry

With the rapid population growth, the need for elevators is being increased. The common type of elevator used in the building industry is a cable-lifted elevator which requires an elevator pit, machine room, and also counter-weight. Hydraulic elevators have been used for high loads and a few floors and do not require to machine room on the roof. Screw systems such as power screw used more for industrial lifters, due to its low speed, frictional losses, and heat production at higher speeds and also the possibility of buckling. Ball screw has soft motion, low sound and vibration, as well as very low frictional losses, which can have a higher speed than a power screw, and therefore may be applied for the elevator. For this purpose, the design of a ball screw-driven elevator for carrying of six people in three floors with a speed of 0.6 m/s has been considered. The conceptual design of the elevator and its components, selection of appropriate ball screw and nut, design of the straight bevel gear, and finally, the determination of the motor power and speed in both conditions with and without counter-weight have been presented. Comparison of these systems with the conventional traction system show that at the same speed, this method requires a motor with higher power in the case of no counter-weights, but if the speed is reduced to 0.45 m/s, a motor with less power is needed and among the other benefits such as the elimination of the pit, machine room, and the counter-weight, makes this method to be more preferable comparatively and easier to implement in the residential buildings. If the counter-weight is used, the power of the motor is reduced significantly and the system may be performed utilizing the existed single-phase current in home buildings using a proper inverter.