Recoil Starter Spring Ramp Torque Absorption

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional recoil starters for small internal combustion engines experience uneven pulling forces and kickback due to abrupt torque changes, leading to user discomfort and potential structural failures from misalignment and buckling of components.

Innovation Solution

A recoil starter system with a drive member, pulley member, and spring member that inhibits relative axial movement, featuring a connecting arrangement with retainers and a spring support ramp to absorb torque fluctuations and provide a smooth pulling force, allowing for rotational movement beyond 90 degrees and preventing unwanted spring motion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional recoil starters are used with rigid spring connections, then the structure is simple, but the pulling force becomes uneven and causes kickback due to abrupt torque changes

Engineering Contradiction:

Improvesmoothness of pulling forceVSAvoidcomplexity of spring connection mechanism

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The spring connection mechanism is designed to be dynamic rather than rigid, allowing the spring to rotate and flex within a defined range (beyond 90 degrees) to accommodate torque fluctuations. This dynamic connection absorbs abrupt torque changes and provides smooth pulling force while maintaining structural simplicity

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system allows the spring connection angle to change dynamically during operation, enabling rotation beyond the traditional 90-degree limit. This parameter change optimizes the force transmission path and reduces kickback while maintaining ease of manufacture

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the spring member is rigidly connected to the drive member and pulley member, then assembly is simple, but misalignment during rotation causes buckling and premature failure

Engineering Contradiction:

Improveresistance to buckling and premature failureVSAvoidcomplexity of retention connection

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The retention members are designed to be flexible rather than rigid, allowing them to deflect and accommodate misalignment between the drive member and pulley member during rotation. This dynamic retention system prevents buckling and premature failure while maintaining assembly simplicity

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The retention members function as flexible elements that can bend and adapt to rotational misalignment, preventing the spring from buckling while maintaining a simple structural design without complex alignment mechanisms

Inventive Principle:

Principle #30Flexible shells and thin films

3Ease of operation

If the spring member is allowed to rotate freely, then the pulling force can accommodate torque variations, but unwanted spring motion occurs causing instability

Engineering Contradiction:

Improveaccommodation of torque variationsVSAvoidstability of spring position

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The spring support ramp is designed to preemptively counteract unwanted spring motion by providing a guiding surface that constrains the spring's rotational path. This preliminary constraint allows torque variation accommodation while preventing instability

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The spring support ramp acts as an intermediary element between the spring member and the housing, mediating the spring's motion to allow necessary rotation for torque accommodation while preventing unwanted movement that would cause instability

Inventive Principle:

Principle #24Intermediary (Mediator)

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 provides a smooth and constant pulling force, reducing user discomfort and preventing premature failure by absorbing torque variations and maintaining structural integrity through the spring member's engagement with the drive and pulley members.

Implementation Method 1

a spring member coupled between the drive member and the pulley member

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The spring member may include portions which engage the outer surfaces drive member and the pulley member to inhibit relative axial movement

Methodology Applied

Scientific EffectSpring: Spring

Implementation Method 3

one retainer includes a radially-extending annular lip, and the other retainer is engageable with the annular lip

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Implementation Method 4

The other retainer may include a plurality of retention members, each of the plurality of retention members being spaced apart about the axis and engageable with the annular lip

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS8132553B2Recoil starter system

Publication Date: 2012.03.13 TECHTRONIC OUTDOOR PRODS TECH

AI summary

A recoil starter system and method. The system may include a drive member, a pulley member, and a spring member. The drive member may include a first retainer, and the pulley member may include a second retainer, the retainers being engageable to connect the drive member and the pulley member and to inhibit relative axial movement between the pulley member and the drive member. The spring member may be configured to absorb and limit the variations in the pulling torque produced by the engine resulting in a smooth and constant pull force.