Rotary Transmitting Assembly Axial Runout Reduction

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Solution Overview

Problem

Conventional rotary motion to linear motion conversion devices face issues with secure positioning and axial runout under high axial and radial loads, leading to potential dislodging of components.

Innovation Solution

A rotary transmitting assembly comprising a housing, hollow shaft, rod member, and bearings with a stopper member, featuring stepped shaft portions and circular support parts to ensure secure axial and radial fixation, reducing axial runout and preventing rod member movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional bearings are used to support the rod member under high axial and radial load, then the rod member can be supported rotatably, but the components are easy to come off and positioning is insecure

Engineering Contradiction:

Improvesecure positioning of bearing componentsVSAvoidresistance to high axial and radial load

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The bearing components are extended in the axial dimension by adding stepped shaft portions that protrude axially from the bearing. This axial extension provides additional contact surfaces and positioning features that prevent the bearing components from coming off under load, thereby improving reliability without compromising load-bearing strength.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The stepped shaft portions are nested within the bearing structure, with inner circumferential stepped shaft portions and outer circumferential stepped shaft portions arranged concentrically. This nested arrangement allows the bearing components to support each other and distribute loads more effectively, enhancing both positioning security and load resistance.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Manufacturing precision

If conventional bearing arrangement is used, then the rod member can rotate on the housing, but axial runout occurs under load

Engineering Contradiction:

Improvereduction of axial runoutVSAvoidhigh axial load on bearing

Core Design Contradiction:

Manufacturing precisionVSForce

Solution Approach 1:

The stepped shaft portions are designed to make preliminary contact with the bearing components before full rotation begins. This preliminary contact establishes precise axial positioning and prevents axial runout from occurring during operation, even under high axial loads.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The stepped shaft portions provide localized contact points with specific geometric features that are optimized for axial positioning. These localized features concentrate the load-bearing function at specific points while maintaining overall rotational freedom, thereby reducing axial runout without compromising the ability to handle high axial loads.

Inventive Principle:

Principle #3Local quality

3Reliability

If conventional ball nut arrangement is used, then rotary motion can be converted to linear motion, but rod member movement in axial direction cannot be prevented

Engineering Contradiction:

Improveprevention of rod member axial movementVSAvoidadditional fixation structures

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The stepped shaft portions serve multiple functions: they provide rotational support, prevent axial movement of the rod member, and maintain positioning of the bearing components. By integrating these multiple functions into a single structural feature, the invention prevents rod member axial movement without significantly increasing device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Ease of manufacture

If bearing components are simplified for ease of assembly, then manufacturing becomes easier, but components become easy to dislodge under load

Engineering Contradiction:

Improveassembly of bearing componentsVSAvoidresistance to component dislodging

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The bearing support structure is segmented into distinct stepped shaft portions (inner and outer circumferential portions) that can be manufactured and assembled separately. Each segment provides specific positioning functions, and their modular nature facilitates ease of assembly while the interlocking geometry of the segments prevents dislodging under load.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9879766B2Rotary transmitting assembly, device for converting rotary motion to linear motion, and motor

Publication Date: 2018.01.30 NIDEC CORP(JP)

AI summary

A rotary transmitting assembly may include a housing having a bearing surface sustaining a bearing; a hollow shaft coupled to the housing, wherein the hollow shaft has an outer circumferential stepped shaft portion and an inner circumferential stepped shaft portion; a rod member coupled to the housing and having a contacting portion and a protruding part, wherein the contacting portion contacts a part of the hollow shaft and the protruding part abuts the inner circumferential stepped shaft portion. The bearing may include a circular inner support part and a circular outer support part supporting the hollow shaft and the rod member, wherein the circular inner support part abuts the outer circumferential stepped shaft portion and the circular outer support part abuts the bearing surface of the housing. A stopper member may be fixed to the rod member, wherein the stopper member abuts the circular inner support part.