A planetary roller screw

Abstract

The invention relates to a planetary roller screw, belonging to the field of roller screw design; including screw, two inner ring gears, nuts, two bearing cages, two wire lock rings, n rollers and positioning pins ; n rollers are evenly distributed on the outer wall of the screw along the circumferential direction; two bearing cages are set on the outer wall of the screw; and the two bearing cages are respectively located at both axial ends of the roller; The two ends extend into two bearing cages respectively; the two internal ring gears are respectively set on the outer walls of the n rollers at both axial ends; the nuts are set on the outer walls of the n rollers; Solid connection; 2 steel wire lock rings are arranged at the axial outer end of the contact between the corresponding bearing cage and the nut; realize axial limit; the invention combines the characteristics of planetary gear transmission and thread transmission to convert rotational motion into linear motion.

Description

technical field [0001] The invention belongs to the field of roller screw design and relates to a planetary roller screw. Background technique [0002] Compared with ball screws, differential planetary roller screws have stronger bearing capacity, higher rigidity, simpler structure, and higher reliability, and are widely used in heavy-duty fields such as braking mechanisms and electromechanical servos. However, the differential planetary roller screw has the problem of unstable transmission ratio. The reason is that the movement and load are transmitted between the roller and the nut only by friction, without any rolling limiting mechanism, and are subject to manufacturing and assembly under load. Influenced by precision, etc., there will be a relative slip between the nut and the roller, resulting in a change in the transmission ratio of the planetary roller screw, making it impossible to achieve a fixed transmission ratio transmission. In the past, the effect of slip was ...

AI Technical Summary

Problems solved by technology

However, the differential planetary roller screw has the problem of unstable transmission ratio. The reason is that the movement and load are transmitted between the roller and the nut only by friction, without any rolling limiting mechanism, and are subject to manufacturing and assembly under load. Influenced by precision, etc., there will be a relative slip between the nut and the roller, resulting in a change in the transmission ratio of the planetary roller screw, and it is impossible to achieve a fixed transmission ratio transmission.

In the past, the influence of slip was eliminated by increasing the pre-tightening force. For example, a planetary roller screw transmission mechanism was proposed in the CN103133619A patent. This method can meet the effect of eliminating slip for small load conditions, but when the load exceeds the preload, it will still cause slip and cannot achieve constant transmission ratio transmission

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