Crowned Gear Noise Reduction in Image Forming Apparatus

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Solution Overview

Problem

Image forming apparatuses experience increased noise due to vibration caused by misalignment between drive and driven gears, particularly in configurations with high torque loads and manufacturing or assembly errors, leading to inefficient gear meshing and image quality deterioration.

Innovation Solution

Employing a crowned gear with a crowning amount less than 50 µm for the driven gear, which reduces vibration and noise by optimizing tooth contact and load distribution during gear meshing, and ensuring the face width of the crowned gear is between 8 mm and 30 mm to maintain effective contact ratio and rotational smoothness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a crowned gear with larger crowning amount is used, then gear meshing stability is improved, but noise and vibration increase due to excessive tooth thickness variation

Engineering Contradiction:
Improvegear meshing stabilityVSAvoidnoise and vibration
Core Design Contradiction:
Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The patent optimizes the crowning amount parameter to a specific range (less than 50 μm) to achieve the best balance between gear meshing stability and noise reduction. This parameter optimization resolves the contradiction by finding the optimal value that provides sufficient stability without excessive tooth thickness variation that causes noise and vibration.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If manufacturing precision is improved to reduce misalignment, then gear meshing efficiency is improved, but manufacturing cost and complexity increase

Engineering Contradiction:
Improvegear alignment precisionVSAvoidmanufacturing complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The crowned gear design incorporates a predetermined crowning amount that proactively compensates for potential misalignment issues before they occur during operation. This beforehand cushioning approach reduces the need for extremely high manufacturing precision while maintaining good gear meshing efficiency, thereby reducing manufacturing complexity and cost.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Force

If the face width of the crowned gear is increased, then load distribution is improved, but rotational smoothness deteriorates due to reduced contact ratio

Engineering Contradiction:
Improveload distributionVSAvoidrotational smoothness
Core Design Contradiction:
ForceVSStability of the object's composition

Solution Approach 1:

The patent optimizes the face width parameter within a specific range (8 mm to 30 mm) to balance load distribution and rotational smoothness. By controlling the face width within this range, the gear achieves adequate load distribution while maintaining sufficient contact ratio for smooth rotation, resolving the contradiction between these two requirements.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3722884B1Image forming apparatus
Publication Date: 2022.08.24 RICOH CO LTD
  • EP3722884B1 patent drawingFigure 1
  • EP3722884B1 patent drawingFigure 2~3
  • EP3722884B1 patent drawingFigure 4A~4B

AI summary

An image forming apparatus (500) includes a driven unit (18, 600) and a drive transmitter (30). The drive transmitter (30) includes a drive source (31), a drive gear (32), and a driven gear (33). The drive source (31) is configured to drive the driven unit (18, 600). The drive gear (32) is configured to receive a driving force from the drive source (31). The driven gear (33) is meshed with the drive gear (32). The drive transmitter (30) is configured to transmit the driving force from the drive source (31) to the driven unit (18, 600). The drive gear (32) or the driven gear (33) is a crowned gear crowning-processed and the crowned gear has a crowning amount less than 50 µm.