Angle Grinder Protective Cover Locking Lever Mechanism

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Solution Overview

Problem

Existing electric hand tools, particularly angle grinders, have protective hoods that are not easily adjustable without tools, which can lead to inadequate protection when the tool bursts, as the current designs often result in unintentional loosening of the protective hood due to the force of detaching tool parts.

Innovation Solution

A design where the locking cam reaches through the protective hood neck radially and the locking lever's pivot axis is parallel to the output shaft, allowing for ergonomic adjustment and secure locking, preventing unintentional loosening, and enabling one-handed operation with a spring-loaded mechanism for easy adjustment and secure fixation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the locking lever is arranged with pivot axis perpendicular to the output shaft (prior art), then the latching mechanism can be actuated, but the protective hood may unintentionally loosen when the tool bursts due to radial force direction

Engineering Contradiction:
Improvesecurity of protective hood positionVSAvoidergonomic adjustability
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent inverts the conventional arrangement by placing the pivot axis of the locking lever parallel to the output shaft instead of perpendicular. This inversion changes the direction of the locking force from radial to axial, preventing unintentional loosening when the tool bursts while maintaining ergonomic adjustability

Inventive Principle:
Principle #13The other way round (Inversion)

2Strength

If the clamp is made of metal and securely fixed to the protective hood neck (prior art), then the connection is strong, but the clamp must first be attached and may require readjustment

Engineering Contradiction:
Improveconnection strengthVSAvoidease of attachment
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The locking lever with spring element automatically engages with the toothed section on the flange when the protective hood is mounted. The spring-loaded mechanism self-adjusts to secure the connection without requiring separate clamp attachment or readjustment operations by the user

Inventive Principle:
Principle #25Self-service

3Reliability

If the locking cam is arranged to reach through the protective hood neck radially (invention), then unintentional loosening is prevented, but the structural complexity increases

Engineering Contradiction:
Improveprevention of unintentional looseningVSAvoidlocking mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking lever serves multiple functions: it provides the locking action through the cam mechanism, acts as the actuating element for adjustment, and works with the spring element to provide both securing and release functions. This multi-functionality reduces the need for separate components despite the radial cam arrangement

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

This design ensures the protective hood remains securely in position even when the tool bursts, providing enhanced user safety and ease of adjustment without requiring tool attachment or repositioning of the machine, while also simplifying manufacturing and maintaining secure attachment to the flange.

Implementation Method 1

The locking lever is pretensioned in the radial direction on a neck of the flange, in particular by means of a spring element

Methodology Applied
Scientific EffectSpring: Spring

Data Source

PatentEP1908549B1Power tool, especially an angle grinder, with a protective cover
Publication Date: 2010.02.17 METABOWERKE
  • EP1908549B1 patent drawingFigure 1~3
  • EP1908549B1 patent drawingFigure 4

AI summary

The device has a protective cover (12) partially surrounding a grinding tool with a base body and provided with a protective cover neck that is connected with the base body. The cover is detachably fixed at a flange (20) by a locking lever (18) in a rotation position, and the locking lever engages an opening in the protective cover with a locking cam. A swiveling axis of the locking lever is arranged parallel to the output shaft, and the openings are arranged in the protective cover neck of the protective cover.