Miniature Gearbox Output Shaft Axial Positioning via Segmented Design
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Solution Overview
Problem
Miniature gearboxes experience axial movement and potential disengagement or sticking issues with their output shafts due to reduced interference fit under alternating loads, affecting performance and service life.
Innovation Solution
The output shaft features a shaft body and a coaxially arranged positioning part with a larger diameter, providing a limiting fit with the planetary carrier and shell, along with a snap ring and spacer for axial stability, preventing movement and ensuring secure attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If interference fit is used to secure the output shaft to the planetary carrier, then initial axial stability is achieved, but the fit magnitude decreases under alternating loads leading to axial movement
Solution Approach 1:
The output shaft is divided into two functional segments: a shaft body for rotation and a separate positioning part for axial constraint. This segmentation allows the positioning part to maintain a dedicated limiting fit with the planetary carrier that is not subject to the same wear and deformation issues as a unified interference fit design, thereby resolving the contradiction between initial stability and long-term durability under alternating loads.
Solution Approach 2:
A positioning part is introduced as an intermediary element between the output shaft and the planetary carrier. This positioning part features a larger diameter and creates a limiting fit relationship that effectively prevents axial movement. The intermediary positioning part absorbs the stress of alternating loads, protecting the primary shaft-body-carrier interface and maintaining reliable axial constraint throughout the service life.
2Ease of manufacture
If the output shaft is designed with a simple cylindrical structure, then manufacturing is easy, but axial movement and disengagement occur under load
Solution Approach 1:
The output shaft is segmented into a shaft body and a positioning part with different diameters. The positioning part has a larger diameter specifically designed to create a limiting fit with the planetary carrier, providing reliable axial positioning. This segmentation maintains relative structural simplicity while effectively preventing axial movement and disengagement under load.
3Reliability
If the positioning part has a larger diameter than the shaft body, then axial limiting fit is improved, but device complexity increases
Solution Approach 1:
The output shaft is segmented into two cylindrical parts with different diameters: a shaft body and a positioning part. The positioning part has a larger diameter that enables effective limiting fit with the planetary carrier, improving reliability. The segmentation is minimal and both parts are simple cylinders, keeping the overall structural complexity low while achieving the desired limiting fit effectiveness.
Data Source
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AI summary
Provided are a micro gearbox and an output shaft thereof, wherein the micro gearbox comprises a shell (1), a planetary carrier (2) which is arranged in the shell (1) and attached to the inner end face of an output end (11) of the shell (1), and an output shaft (3) which penetrates through the output end (11) of the shell (1) and is rotatably positioned on the planetary carrier (2); the output shaft (3) comprises a shaft body (31), and a positioning part (32) coaxially arranged at the tail end of the shaft body (31), the positioning part (32) and the planetary carrier (2) are in limiting fit along the center axis of the output shaft (3) and towards the outer end of the shaft body (31), and the outer end of the shaft body (31) and the outer end face of the output end (11) are in limiting fit along the center axis and towards the tail end of the shaft body (31); in this way, axial movement of the output shaft (3) is effectively avoided, the overall operating stability of the micro gearbox is improved, the service life of the micro gearbox is prolonged, and the micro gearbox is simple in structure and convenient to machine and assemble.