This paper considers the issue of improving the reliability of an electromechanical actuator in which the possibility of ball screw jamming has been excluded. For this purpose, an analysis of design solutions which allows to increase the reliability of an electromechanical ball screw linear actuator was carried out, design of ball screw with a separator was developed and patented, experimental studies of an actuator prototype with ball screw with a separator were carried out. The proposed constructive solution of ball screw, in which the nut is made without an internal thread, significantly simplifies the design and manufacturing technology. For experimental determination of static and dynamic characteristics of the actuator containing ball screw with a separator a mathematical model has been designed and a prototype similar to the electromechanical actuator with ball screw with ball recirculation has been made. The experiments showed that compared actuators have practically same static and dynamic characteristics, but the efficiency of the ball screw with a separator is lower than that of ball screw with ball recirculation, the reasons for the decrease and ways to increase efficiency in ball screw with a separator are considered.

No abstract

The work is devoted to the topical problem of choosing a scheme of a linear electromechanical drive, developed as an alternative to an autonomous electro-hydraulic drive. Mass characteristics of the main functional elements of the actuators: electric motors and ball screws are considered. Synchronous motors and a collector motors were considered in this work as an electric motor. Ball-screw transmissions with separator and ball-screw transmissions with recirculation of balls were considered in this work as a ball-screw transmission. Comparison was made according to functional, technological and economic criteria of two schemes for construction of linear electromechanical drives: with intermediate mechanical transmission based on a collector motor and based on a permanent magnet synchronous motor without an intermediate mechanical transmission. The comparison showed that the scheme with an intermediate mechanical transmission has better mass characteristics compared to the scheme without an intermediate mechanical transmission with similar dynamic characteristics. The presented comparison results can be useful in solving the problem of choosing schemes for newly developed electric electromechanical steering drives.

Extensive use of ball screws with separators is due to manufacturing simplicity and increased reliability as compared to ball screws with recirculating rolling elements. The issues of determining the efficiency of such mechanisms have not been sufficiently studied. The paper presents analytically derived primary dimension ratios for parts of ball screws with separators, taking into account those tolerances that should be observed to ensure that the mechanism assembly is guaranteed and the preloads affecting the breakaway forces and the mechanism efficiency are prevented. We provide guidelines for designing parts of ball screws with separators. We plotted the interacting forces in the parts constituting ball screws with separators and analytically determined the efficiency of such mechanisms as a function of contact angles and lead angles. The experimental investigation results concerning electro-mechanical drive prototypes based on ball screws confirm the analytical expressions obtained. Adhering to the dimension ratios proposed for parts of ball screws with separators reveals that the analytically and experimentally determined efficiency values converge. Using the efficiency plots presented for ball screws with separators while designing electromechanical drives is appropriate to assess energy losses in mechanical transmissions

No abstract