Angle Grinder Protective Hood Locking Mechanism

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Solution Overview

Problem

Existing electric tools, such as angle grinders, often lack effective and simple safety mechanisms to securely attach and prevent unauthorized removal of protective hoods, leading to potential user injury from sparks and tool fragments.

Innovation Solution

The implementation of a safety device comprising a safety ring, safety screws, and a safety clip that securely attaches to the tool's bearing plate, with features like axial grooves and radial projections to block disassembly, making it difficult for users to remove the protective hood without authorization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protective hood is provided to protect users from sparks and tool fragments, then user safety is improved, but the device complexity increases due to additional mounting and locking mechanisms

Engineering Contradiction:
Improveuser safetyVSAvoidmounting mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking mechanism is segmented into multiple independent locking elements (first locking mechanism and second locking mechanism) that can engage with corresponding detents separately, allowing the protective hood to be secured through multiple discrete locking actions rather than a single complex mechanism

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The protective hood is pre-equipped with multiple locking elements and corresponding detents are pre-positioned on the bearing plate, enabling the user to perform preliminary locking actions during assembly that prevent accidental removal later

Inventive Principle:
Principle #10Preliminary action

2Reliability

If a locking device is added to prevent unauthorized removal of the protective hood, then security is improved, but the ease of operation deteriorates due to more complex user interactions required

Engineering Contradiction:
Improvesecurity against unauthorized removalVSAvoidease of hood removal
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The locking mechanisms are designed to be dynamically engageable and disengageable through simple user actions (such as pressing release elements or rotating components), allowing the protective hood to transition between locked and unlocked states without complex procedures

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The security function is divided into multiple independent locking mechanisms that can be engaged or disengaged separately, allowing partial access or incremental security adjustments rather than requiring complete disassembly of a single complex lock

Inventive Principle:
Principle #1Segmentation

3Reliability

If multiple locking mechanisms are implemented to make removal difficult, then security is improved, but the device complexity increases due to additional components

Engineering Contradiction:
Improvesecurity against tamperingVSAvoidnumber of locking components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Multiple locking mechanisms are merged into an integrated assembly where locking elements, detents, and release mechanisms work together as a unified security system, reducing the number of separate components compared to implementing multiple independent locking devices

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The locking mechanisms serve multiple functions: they prevent unauthorized removal, provide tamper detection capability, and enable controlled access during maintenance, allowing a single set of locking components to fulfill several security and operational requirements

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

Data Source

PatentEP3892420B1Electrical tool
Publication Date: 2025.01.29 C & E FEIN GMBH & CO KG
  • EP3892420B1 patent drawingFigure 1
  • EP3892420B1 patent drawingFigure 2
  • EP3892420B1 patent drawingFigure 3

AI summary

The invention relates to an electric tool (1), in particular an angle grinder (2), with a drive motor (4) housed in a housing (3) which drives a rotor shaft (5), with a tool spindle (7) having a tool holder (8) which is connected to the rotor shaft (5) by an angle gear (6) which is housed in a gear head (9), with a bearing plate (10) having a spindle passage (11) in which the tool spindle (7) is rotatably mounted, wherein the bearing plate (10) has a mounting flange (12) on which a protective hood (13) can be rotatably mounted, the removal of which from the mounting flange (12) is at least made more difficult by a locking device (21).The locking device (21) is selected from a group comprising at least one locking pin (20) received in the receiving flange (12), a locking ring (27) preferably secured to the receiving flange (12) by a snap-fit ​​connection or by a press-fit connection, a locking plate (33) screwed to the bearing plate (10) by several locking screws (34), a locking clip (44) attached to the bearing plate (10) and a locking tab (50) formed on the protective hood (13).