Rotating Eccentric Locking Element for Tool Holder Wear Reduction

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Solution Overview

Problem

The existing tool holders for hand-held power tools, such as demolition hammers, often feature wear-prone folding mechanisms that can lead to the tool being accidentally released and falling out due to mechanical wear over time, compromising operational reliability.

Innovation Solution

A tool holder design with a rotatably mounted locking element that is eccentrically positioned relative to the receiving element, allowing for a secure locking and unlocking mechanism without the need for a folding mechanism, utilizing a spring-loaded locking sleeve that engages the tool in a form-fitting manner, ensuring the tool remains securely in place.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a folding locking mechanism is used, then the tool holder can lock and release the tool, but the mechanism becomes wear-prone and may open on its own after some use

Engineering Contradiction:
Improvelocking mechanism reliabilityVSAvoidservice life of locking mechanism
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent replaces the folding locking mechanism with a rotatable locking element that rotates about the receiving element. This substitution eliminates the folding action that causes wear and eventual failure, while maintaining the locking and releasing functions through a different mechanical motion (rotation instead of folding).

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

Instead of using a folding motion to achieve locking and releasing, the invention inverts the approach by using rotational motion. The locking element rotates about the receiving element, with the locking position achieved through rotation rather than folding, thereby solving the wear problem inherent in folding mechanisms.

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

2Ease of operation

If a folding mechanism is used, then the tool can be locked and released, but the mechanism is stiff when new and becomes worn after use

Engineering Contradiction:
Improvelocking and releasing operationVSAvoidmechanical wear resistance
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent substitutes the folding mechanical system with a rotational mechanical system. The locking element rotates about the receiving element, providing a different kinematic chain that avoids the stiffening and wear issues characteristic of folding mechanisms while preserving the ease of locking and releasing operations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention introduces dynamic characteristics by allowing the locking element to rotate freely about the receiving element, rather than relying on a folding mechanism that becomes stiff when new. The rotational motion provides consistent operational characteristics throughout the service life of the locking mechanism.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3826811B1Tool holder and hand-held machine tool
Publication Date: 2024.09.18 HILTI AG
  • EP3826811B1 patent drawingFigure 1
  • EP3826811B1 patent drawingFigure 2
  • EP3826811B1 patent drawingFigure 3

AI summary

The invention relates to a tool holder for a hand-held machine tool, in particular for a demolition breaker or hammer drill, comprising a holder element for holding a tool and a locking element which is mounted on the holder element in an eccentric and rotatable manner for locking the tool in the tool holder. The locking element can be brought from an unlocked state, in which the tool can be removed from the holder element, into a locked state, in which the locking element surrounds the tool in a formfitting manner, and vice versa by rotating the locking element about the holder element.