Toothed Belt Pulley Pitch Offset for Bicycle Mesh Stability

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Solution Overview

Problem

Toothed belt drives in bicycles, especially those with less torsion-resistant frames, experience mesh failures due to misalignment and changes in center distance under load, leading to potential injuries and belt breakage.

Innovation Solution

A toothed belt pulley with a predetermined pitch smaller than the toothed belt pitch, featuring grooves and teeth configuration that aligns with the belt's profile geometry to maintain proper meshing even under torsion and high drive torques.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a toothed belt pulley with pitch matching the toothed belt is used, then the meshing is precise under ideal conditions, but mesh failures occur under load due to frame torsion and center distance changes

Engineering Contradiction:

Improvepitch matchingVSAvoidmesh failure prevention

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent changes the pitch parameter of the toothed belt pulley from matching the belt pitch exactly to being smaller than the belt pitch. This parameter modification creates clearance that allows the pulley to accommodate frame torsion and center distance changes without causing mesh failures, while still maintaining reliable power transmission.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the center distance is shortened to accommodate flexible frames, then the frame flexibility is maintained, but the toothed belt forms an arc and causes mesh failure

Engineering Contradiction:

Improveframe flexibilityVSAvoidmesh failure prevention

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies beforehand cushioning by designing the pulley with a smaller pitch than the belt, which creates built-in clearance that cushions against the adverse effects of center distance shortening and frame torsion. This pre-designed tolerance prevents the belt from forming harmful arcs and avoids mesh failures under variable operating conditions.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Weight of moving object

If conventional toothed belt pulleys are used with flexible frames, then the bicycle structure is lightweight, but mesh failures lead to safety risks

Engineering Contradiction:

Improvebicycle weightVSAvoidmesh failure risks

Core Design Contradiction:

Weight of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of frame flexibility and center distance changes into a beneficial feature by designing the pulley with smaller pitch. The clearance created by this design allows the flexible frame to move without causing mesh failures, transforming what was previously a harmful factor into an acceptable characteristic of the system.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS20250347338A1Toothed Belt Pulley with Improved Mesh and Belt Drive, Bicycle and Kit

Publication Date: 2025.11.13 NICOLAI KARLHEINZ

AI summary

A toothed belt pulley for a toothed belt with a predetermined pitch, the toothed belt pulley comprises teeth arranged along a circumferential direction of the toothed belt pulley and grooves arranged in the circumferential direction between in each case adjacent teeth of the toothed belt pulley, and the toothed belt pulley comprises a pitch which is smaller than the pitch of the toothed belt. A belt drive comprising a toothed belt pulley and a toothed belt, and a kit for a belt drive comprising at least two toothed belt pulleys for the same toothed belt of predetermined pitch. Finally, a bicycle with a toothed belt pulley and/or a belt drive is proposed.