Rotation Shaft Mounting Structure With Relaxed Tolerance Fit

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Solution Overview

Problem

Existing mounting structures for bearings and power transmitters on rotation shafts in conveyors require strict dimensional tolerances, leading to increased manufacturing costs due to difficulty in processing.

Innovation Solution

A mounting structure for a rotation shaft with a first portion having a circular cross-section and a second portion with a non-circular cross-section, where the bearing is mounted on the first portion and the power transmitter is engaged with the second portion, allowing for relaxed dimensional tolerances while maintaining secure mounting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If strict dimensional tolerances are set for the inner circumferential surface of the power transmitter, then the mounting stability is improved, but the manufacturing cost increases

Engineering Contradiction:
Improvemounting stabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The rotation shaft is segmented into a first portion with a first outer circumferential surface and a second portion with a second outer circumferential surface having different diameters. The bearing is mounted on the first portion while the power transmitter is mounted on the second portion, allowing different dimensional tolerances for different mounting surfaces. This segmentation enables the power transmitter's inner circumferential surface to have relaxed tolerances while maintaining mounting stability through the differentiated shaft portions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different portions of the rotation shaft are given different local qualities in terms of dimensional precision. The first outer circumferential surface (for the bearing) and the second outer circumferential surface (for the power transmitter) have different diameters and can have different tolerance levels. This local differentiation allows the power transmitter mounting area to have relaxed tolerances while other areas maintain higher precision where needed.

Inventive Principle:
Principle #3Local quality

2Reliability

If strict dimensional tolerances are set for the rotation shaft components, then the mounting stability is improved, but the manufacturing process complexity increases

Engineering Contradiction:
Improvemounting stabilityVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The rotation shaft is divided into distinct segments (first portion and second portion) with different outer circumferential surfaces. This segmentation allows each portion to be manufactured with appropriate tolerances for its specific function, simplifying the overall manufacturing process by avoiding the need for uniform strict tolerances across the entire shaft while still maintaining mounting stability through the differentiated structure.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4692954A1Mounting structure, developing device, and image forming apparatus
Publication Date: 2026.02.11 RICOH CO LTD
  • EP4692954A1 patent drawingFigure 1
  • EP4692954A1 patent drawingFigure 2~3
  • EP4692954A1 patent drawingFigure 4~6

AI summary

A mounting structure includes a rotation shaft (60), a bearing (52), and a power transmitter (54). The rotation shaft (60) has a first portion (60a) and a second portion (60b). The first portion (60a) has a first outer circumferential surface. The second portion (60b) is near the first portion (60a) in an axial direction of the rotation shaft (60) and has a second outer circumferential surface inside the first outer circumferential surface of the first portion (60a). The second outer circumferential surface has a non-circular cross section. The bearing (52) is on the first portion (60a) of the rotation shaft (60) and rotatably supports the rotation shaft (60). The power transmitter (54) covers a part of the first outer circumferential surface of the first portion (60a) and is engaged with the second outer circumferential surface of the second portion (60b) to transmit a rotational force to the rotation shaft (60).