Chain Tightener With Irreversible Wedge for Torque Reversal

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Solution Overview

Problem

Existing mechanical power transmission chain systems face challenges in maintaining correct chain tightening levels over time, especially in applications with torque reversals, such as motorcycle primary transmission systems, due to chain wear and elastic lengthening, leading to noise, flapping, and reduced system lifespan.

Innovation Solution

A mechanical power transmission chain system with a tightener featuring a base, a tightening shoe in dragging contact with the chain, and a sliding wedge under the thrust of a first spring, accompanied by an elastic thrust member to ensure progressive tightening, capable of withstanding high stresses and torque reversals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If a quadrilateral tightening system is used, then chain lengthening due to wear can be recovered, but the system cannot oppose chain movement during torque reversal

Engineering Contradiction:

Improvechain tightening capabilityVSAvoidability to handle torque reversal

Core Design Contradiction:

Duration of action of moving objectVSAdaptability or versatility

Solution Approach 1:

The tightening shoe is made dynamically adaptable through a nonreturn mechanism that allows it to move with the chain during torque reversal while maintaining tightening capability. The shoe can transition between fixed and movable states depending on the operational phase, enabling it to handle both chain wear compensation and torque reversal conditions effectively.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If traveling circular trajectory shoes are used, then torque reversal can be opposed, but only small chain-lengthenings can be compensated

Engineering Contradiction:

Improveability to handle torque reversalVSAvoidchain tightening capability

Core Design Contradiction:

Adaptability or versatilityVSDuration of action of moving object

Solution Approach 1:

The tightening system is segmented into distinct functional components: a base for mounting, a movable tightening shoe for applying force to the chain, and a nonreturn mechanism for controlling movement direction. This segmentation allows each component to specialize in specific functions, enabling the system to handle both significant chain lengthening and torque reversal effectively.

Inventive Principle:

Principle #1Segmentation

3Force

If spring-thrust tightening shoes are used, then chain tightening is provided, but the shoe cannot oppose high torque reversals

Engineering Contradiction:

Improvechain tightening forceVSAvoidability to handle high torque reversal

Core Design Contradiction:

ForceVSAdaptability or versatility

Solution Approach 1:

The spring thrust is designed to provide sufficient tightening force under normal operating conditions, while the nonreturn mechanism provides additional capability to handle excessive forces during torque reversal. The spring force is calibrated to maintain proper chain tension during motor pulling phases, while the mechanical nonreturn structure engages to prevent shoe movement during high-stress braking phases.

Inventive Principle:

Principle #16Partial or excessive action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system effectively maintains adequate chain tightening at all motor speed conditions, even when the chain is worn and lengthened, reducing noise and extending the transmission system's lifespan by compensating for irreversible and reversible chain length changes.

Implementation Method 1

a sliding wedge under the thrust of a first spring in an irreversible manner between the base and the shoe

Methodology Applied

Scientific EffectSpring: Spring

Implementation Method 2

between said wedge and said shoe there is an elastic thrust member for thrusting the shoe in the tightening direction

Methodology Applied

Scientific EffectElastic thrust: Elasticity

Data Source

PatentUS7338399B2Chain power-transmission system with mechanical tightener

Publication Date: 2008.03.04 SOC ITALANA CATENE CALIBRATE REGINA

AI summary

A mechanical power-transmission system with chain including a mechanical tightener acting on a branch of the chain and having in turn a base, a tightening shoe in dragging contact with the chain and a sliding wedge under the thrust of a first spring in an irreversible manner between the base and the shoe to cause progressive withdrawal of the base and the shoe in the tightening direction of the chain so that between the wedge and the shoe there is an elastic thrust member for thrusting the shoe in the tightening direction.