Hand-Held Power Tool Locking Mechanism for Secure Tool Exchange
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Solution Overview
Problem
The handling of hand-held power tools is cumbersome due to the need for simultaneous axial movement of the actuating sleeve and screwdriver bit for unlocking, and the risk of tilting or slipping when attaching socket wrenches, leading to discomfort and instability.
Innovation Solution
A locking device with a retaining element, such as a C-ring, and a spring element that applies a predetermined force to hold the actuating element in place, combined with an elastically deformable holding member for secure attachment of tools with internal polygonal couplings, ensuring easy and secure tool exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an actuating sleeve is used to unlock and remove the screwdriver bit, then the locking function is achieved, but both the actuating sleeve and screwdriver bit must be moved in the same axial direction which makes handling cumbersome
Solution Approach 1:
The locking device is segmented into independent functional components: the actuating sleeve for unlocking, the retaining element for securing the locked position, and the spring element for automatic return. This segmentation allows each component to perform its specific function independently, simplifying the operation sequence and making handling more convenient.
Solution Approach 2:
Instead of requiring the user to actively disengage the locking mechanism by moving the actuating sleeve in the same direction as bit removal, the design inverts the logic: the actuating sleeve moves in the opposite direction (axially towards the holder) to trigger unlocking, while the bit is removed in the conventional direction. This inversion separates the unlocking motion from the bit removal motion, greatly improving ease of operation.
2Reliability
If a U-shaped retaining spring is used to fix the socket wrench, then the connection is achieved, but tilting of the socket wrench or unintentional slippage of the retaining spring must be avoided which reduces user comfort
Solution Approach 1:
The retaining function is extracted from the main body of the tool holder and implemented as a separate, dedicated retaining element (such as a C-ring with radial extensions) that can be independently optimized. This retaining element works in conjunction with a groove structure to provide positive mechanical engagement, eliminating the need for complex spring mechanisms and reducing the risk of tilting or slippage, thereby improving user comfort.
Solution Approach 2:
The retaining element is designed to engage uniformly with the groove structure in the tool holder, creating an equipotential mechanical connection that distributes forces evenly. This uniform engagement prevents tilting and ensures stable connection without requiring the user to worry about misalignment or slippage, enhancing overall user comfort and confidence during operation.
3Device complexity
If the actuating element is not blocked in the locking position, then the structure is simpler, but the actuating element may move unintentionally during operation reducing reliability
Solution Approach 1:
The retaining element with radial extensions is positioned to preemptively block the actuating element in its locked position before any unintentional movement can occur. This preliminary blocking action prevents the need for complex locking mechanisms while ensuring the actuating element remains firmly in place during operation, achieving both simplicity and reliability.
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 enables reliable and stable connection of tools, simplifying the handling and secure attachment of both insert and application tools, enhancing user comfort and tool holder stability.
Implementation Method 1
a spring element which is designed to actuate the actuating element with a predetermined spring force in the direction of the first insertion tool into the locking position
Implementation Method 2
an elastically deformable retaining element can be attached for holding the second insert tool
Data Source
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AI summary
In a handheld machine tool comprising a tool holder (150), which has an inner polygonal holder (290) and an outer polygonal holder (210), wherein the inner polygonal holder (290) is designed to be connected to a first inserted tool that can be locked in the inner polygonal holder (290) by means of a locking device (240) associated with the tool holder (150), and the outer polygonal holder (210) is designed to be connected to a second inserted tool having an inner polygonal coupling that can be slid onto the outer polygonal holder (210), the locking device (240) comprises an actuating element (244) which, in order to unlock the first inserted tool, can be displaced from a locked position into an unlocked position in an axial direction pointing away from the first inserted tool.