Rotary-linear movement change mechanism and actuator

Abstract

The invention provides a rotary-linear movement change mechanism and an actuator, capable of simultaneously accomplishing two contradictious technical objects of minaturization and large action amount. The rotary-linear movement change mechanism (3) comprises a planet gear mechanism (5), first, second screw shafts (8,32), a transmission unit (7), a main shaft (9) and a sleeve (33). The planet gear mechanism (5) drives a sun gear (20) by an electric machine (4) to make a planet gear (24) rotate and revolve. The first screw shaft (8) is integrated with the transmission unit (7), thus the main shaft (9) linearly moves. The second screw shaft (32) is integrated with a planet gear shaft (23). The transmission unit (7) rotates together with the revolution of the planet gear (24) and linearly moves along the second screw shaft (32). A cover (2B) makes the sleeve not rotate and freely integrated with the transmission unit (7) to perform the linear movement.

Description

technical field [0001] The present invention relates to a rotation-linear motion conversion mechanism that converts rotation into linear motion, and an actuator using the rotation-linear motion conversion mechanism. Background technique [0002] Generally, a thread is used as a general rotary-linear motion conversion mechanism for converting rotary motion into linear motion (linear motion). For example, there is a configuration in which a planetary gear mechanism is combined with a thread as a reduction gear mechanism disclosed in Patent Document 1. The planetary gear mechanism has a drive shaft (input shaft), a driven shaft (output shaft), a fixed shaft, and a common basic shaft. ), a planetary gear, and a planetary carrier (output shaft) that transmits torque through the orbital motion of the planetary gear and rotates. [0003] The planetary differential screw type rotary-linear motion conversion mechanism disclosed in the above-mentioned Patent Document 1 incorporates a...

AI Technical Summary

Problems solved by technology

[0005] However, in the above-mentioned conventional planetary differential screw type rotary-linear motion conversion mechanism, the stroke of the control shaft is ensured by the amount of movement of the sun shaft, so if the maximum stroke of the control shaft is long, the overall length of the sun shaft will also become longer. Since the amount of movement increases, there is a problem that it becomes larger in the direction of movement

In addition, in the case of accelerating the linear motion of the sun shaft, it is possible to cope with it by increasing the rotation speed of the nut. However, if the rotation speed is increased too much, the screw parts of the nut, the planetary shaft, and the sun shaft are worn away, and cracks are likely to occur. Issues that cause reduced durability

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