Protective Hood End Stop for Kinetic Energy Absorption

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Solution Overview

Problem

Existing handheld work apparatuses, such as cut-off machines, face challenges in reliably absorbing and dissipating the kinetic energy of cutting wheel parts that break during operation, as the protective hood's freedom of movement is limited, potentially leading to damage to components.

Innovation Solution

The apparatus incorporates an operating stop designed as an energy absorption element that moves away from a counter-body upon excess load, featuring a predetermined breaking point or material deformation to absorb kinetic energy, and is integrated with a counter-body and end stop to restrict pivoting movement, ensuring reliable energy dissipation and component protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the protective hood is designed with limited freedom of movement to maintain structural stability, then the reliability of the apparatus is improved, but the protective hood cannot reliably dissipate high kinetic energy during burst tests

Engineering Contradiction:

Improvestructural stabilityVSAvoidkinetic energy dissipation

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The operating stop is designed to transition from a rigid constraint to a dynamic energy absorption element. Upon impact with the counter-body during burst tests, the operating stop deforms plastically or breaks at a predetermined point, allowing the protective hood to move dynamically and absorb kinetic energy while maintaining structural integrity during normal operation

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The operating stop's mechanical properties are designed to change under different load conditions. During normal operation, it maintains rigid constraints, but under excessive load (burst test conditions), it undergoes material deformation or breaking, changing from a rigid structure to an energy-absorbing element that allows controlled movement

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If the operating stop is designed as a rigid constraint to reliably restrict pivoting movement, then the ease of operation is improved, but the counter-body components are damaged during burst tests due to excessive kinetic energy

Engineering Contradiction:

Improvepivoting movement restrictionVSAvoidcounter-body component integrity

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The operating stop is designed with a predetermined breaking point or material deformation characteristic that acts as a safety mechanism. This design anticipates potential excessive loads during burst tests and prepares the system to absorb energy through controlled deformation, preventing damage to the counter-body components before the damage can occur

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The operating stop's material deformation or breaking under excessive load, which might seem like a failure, is actually designed to convert the harmful kinetic energy into beneficial energy absorption. This controlled failure mode protects the counter-body components by dissipating energy that would otherwise cause damage

Inventive Principle:

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

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 effectively restricts the pivoting movement of the protective hood, preventing damage to the counter-body and ensuring safe operation even in burst tests by absorbing excess kinetic energy, thus protecting the apparatus components.

Implementation Method 1

The operating stop is designed as an energy absorption element which, in the event of an excess load acting on the operating stop due to the counter-body, moves away from the counter-body in order to absorb kinetic energy of the protective hood

Methodology Applied

Scientific EffectEnergy absorption: Deformation

Implementation Method 2

The operating stop restricts the pivoting movement of the protective hood to the second operating position

Methodology Applied

Scientific EffectMechanical constraint: Mechanical Force

Data Source

PatentUS20250326042A1Handheld work apparatus

Publication Date: 2025.10.23 ANDREAS STIHL AG & CO KG

AI summary

A handheld work apparatus includes a housing (2). A drive motor (3) is arranged in the housing (2) for driving a tool (2) that rotates about an axis of rotation (8). A protective hood (51) at least partially covers the tool (5). An operating stop (120) is fixed relative to the housing (2) and a counter-body (110) is arranged on the protective hood (51) and corresponds to the operating stop (120). The operating stop (120) is designed as an energy absorption element which, in the event of an excess load acting on the operating stop (120) due to the counter-body (110), moves away from the counter-body (110) in order to absorb kinetic energy of the protective hood (51) and to protect components of the counter-body (110). The work apparatus (1) includes an end stop (101) for restricting the rotational movement of the protective hood (51) to an end position (25).