PLANETARY TYPE ROTARY-LINEAR MOTION CONVERTING DEVICE

摘要

A planetary type rotary-linear motion converting device configured in such a manner that a sun shaft has a large amount of stroke, that the device can be produced at high productivity, and that the device is highly durable.  A planetary type rotary-linear motion converting device comprises: a sun shaft (1) having a sun gear (11) and a helical ridge (12); planetary shafts (4) having planetary gears (41) meshing with the sun gear (11) of the sun shaft (1) and also having helical grooves (42) engaging with the helical ridge (12) of the sun shaft (1); and a nut (2) having an internal gear (21) meshing with the planetary gears (41) of the planetary shafts (4) and engaging with the helical grooves (42) in the planetary shafts (4).  When the sun shaft (1) is rotated relative to the nut (2), the planetary shafts (4) move linearly relative to the sun shaft (1) in the axis direction of the sun shaft (1).  Those regions of the planetary shafts (4) in which the planetary gears (41) are formed and those regions of the planetary shafts (4) in which the helical grooves (42) are formed are separated from each other in the axis direction of the planetary shafts (4).  The sun gear (11) meshing with the planetary gears (41) of the planetary shafts (4) is formed on the helical ridge (12) of the sun shaft (1).