Starter Device Rope Guide Deflection Roller Ergonomics

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Solution Overview

Problem

Existing starter devices for internal combustion engines in backpack power tools have complex configurations that complicate the starting process, particularly when the starter handle needs to be oriented differently.

Innovation Solution

A starter device with a rope guide featuring a deflection roller and a rope outlet opening that extends across a peripheral angle of at least 60°, allowing the starter handle to be positioned at various angles without requiring a complex rotary bearing, and incorporating a guide element to securely hold the starter rope, reducing friction and wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a complex rotary bearing is used to enable the starter handle to be positioned at different angles, then the adaptability of the starter device is improved, but the device complexity increases

Engineering Contradiction:

Improveability to position starter handle at different anglesVSAvoidcomplexity of rotary bearing mechanism

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent removes the complex rotary bearing mechanism entirely and replaces it with a simplified rope guide system consisting of a deflection roller and an arc-shaped rope outlet opening. The starter rope is guided through the arc-shaped opening, allowing the handle to be pulled at different angles without requiring a rotary bearing to accommodate angular movement.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The deflection roller serves as an intermediary element that redirects the starter rope through the arc-shaped rope outlet opening. This mediator allows the rope to change direction smoothly, enabling the handle to be positioned at various angles while maintaining a simple overall structure without complex rotary mechanisms.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the rope outlet opening is arranged along a circumferential section of the deflection roller with a peripheral angle of at least 60°, then the ease of operation is improved, but the area occupied by the rope guide increases

Engineering Contradiction:

Improveease of orienting starter handleVSAvoidarea occupied by rope guide

Core Design Contradiction:

Ease of operationVSArea of stationary object

Solution Approach 1:

The rope outlet opening is designed as an arc-shaped circumferential section of the deflection roller, utilizing curvature to enable angular adjustment. The arc shape with a peripheral angle of at least 60° allows the starter rope to be pulled at multiple angles while maintaining a compact design that efficiently uses the available space around the deflection roller.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Reliability

If a guide element is arranged at the rope outlet opening to hold the starter rope, then the reliability of the starter device is improved, but the device complexity increases

Engineering Contradiction:

Improvesecurity of starter rope positioningVSAvoidcomplexity of guide element structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A guide element is positioned specifically at the rope outlet opening where the starter rope exits the arc-shaped section. This localized guide ensures the rope maintains proper positioning and alignment at the critical exit point, improving reliability without requiring a complex overall structure. The guide element is only where needed, not throughout the entire mechanism.

Inventive Principle:

Principle #3Local quality

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 solution simplifies the starting process by enabling easy orientation of the starter handle and reducing the forces required to start the engine, while also minimizing wear and preventing damage to the rope guide.

Implementation Method 1

reducing friction and wear

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

reducing friction and wear

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 3

minimizing wear and preventing damage to the rope guide

Methodology Applied

Scientific EffectWear: Wear

Data Source

PatentUS10794351B2Starter device for an internal combustion engine and backpack power tool with an internal combustion engine and with a starter device for the internal combustion engine

Publication Date: 2020.10.06 ANDREAS STIHL AG & CO KG

AI summary

A starter device for an internal combustion engine has a rope pulley and a starter rope wound onto the rope pulley. A rope guide guiding the starter rope from the guide pulley to a rope outlet opening of the starter device is provided. A guide element positioned at the rope outlet opening holds the starter rope in the rope outlet opening. The rope guide has at least one deflection element that is arranged at the rope outlet opening. The deflection element has two tangents which are intersecting each other at an angle of less than 90°. The deflection element has a minimal radius of a length that is longer than a length of a diameter of the starter rope. The starter handle can be positioned relative to the rope outlet opening at different orientations and enables ergonomic starting of the internal combustion engine of a backpack power tool.