Rounded Rectangular Coupling for Image Forming Apparatus
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Solution Overview
Problem
Existing driving force transmission units in image forming apparatuses suffer from misalignment of shaft axes, leading to irregular contact at coupling contact portions, uneven driving force transmission, and potential damage to couplings during engagement and disengagement, resulting in vibrations and image defects.
Innovation Solution
A driving force transmission unit with a first coupling having a rounded rectangular shape in cross-section, including a circular arc portion, and a second coupling with corresponding contact portions, where the contact areas are positioned to prevent tilting and ensure point contact, reducing contact resistance and preventing damage during engagement and disengagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional couplings with contact portions are used to transmit rotary driving force, then driving force transmission is achieved, but misalignment of shaft axes causes irregular contact and potential damage to couplings
Solution Approach 1:
The invention replaces conventional flat or angular contact portions with curved surface contact portions. The drive-side coupling has a curved outer surface while the driven-side coupling has a curved inner surface, allowing point contact that naturally accommodates shaft misalignment without causing irregular stress concentration or coupling damage.
2Ease of operation
If shaft alignment is not precisely maintained, then ease of assembly is improved, but irregular contact at coupling portions causes uneven driving force transmission and vibrations
Solution Approach 1:
The curved contact surfaces allow the couplings to self-align during assembly, accommodating minor shaft misalignments while maintaining stable driving force transmission. The curvature enables smooth rolling contact that reduces vibrations and ensures uniform force distribution.
Solution Approach 2:
The curved surface geometry enables the couplings to automatically adjust and align themselves during assembly and operation, eliminating the need for precise pre-alignment of shafts. The design self-corrects for minor misalignments through the natural rolling motion of the curved contact surfaces.
3Power
If conventional coupling contact portions are used, then driving force transmission is achieved, but contact resistance increases during engagement and disengagement
Solution Approach 1:
The curved contact surfaces enable point contact with rolling motion during engagement and disengagement, significantly reducing friction and contact resistance compared to conventional flat or sliding contact mechanisms. This reduces energy loss while maintaining effective torque transmission.
Data Source
AI summary
A driving force transmission unit includes a first coupling, a second coupling, and a first rotary shaft. The first coupling includes a first contact portion and a hole, the inner circumferential surface of which has a rounded rectangular shape in cross section including a circular arc portion. The second coupling includes a second contact portion disposed at a position facing the first contact portion to contact the first contact portion along a direction of rotation of the second coupling. The first rotary shaft is connected to the first coupling and includes a shaft portion, an outer circumferential surface which has a rounded rectangular shape in cross section including a circular arc portion inserted into the hole of the first coupling.