Angled Locking Lever Layout for Ergonomic Hand-Guided Tools
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Solution Overview
Problem
Hand-held work devices with safety levers require simultaneous operation of locking and actuating levers, which is uncomfortable and not intuitive, often necessitating the operator to release their grip on the handle.
Innovation Solution
The ergonomic design positions the locking lever's axis of rotation at an angle between 10° to 60° relative to the handle's longitudinal axis, allowing the locking lever to be actuated with the thumb and the actuating lever with the index finger without compromising the grip, featuring a spring unit for biasing the locking lever and wing elements for easy operation in various grip positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the locking lever is arranged parallel to the handle's longitudinal axis, then the structure is simple, but the operator must push the thumb forward in the longitudinal direction which requires abandoning the fixed hand position
Solution Approach 1:
The locking lever is arranged asymmetrically at an angle of 10° to 60° relative to the handle's longitudinal axis, specifically oriented toward the rear end of the handle. This asymmetric angular arrangement allows the thumb to operate the locking lever through natural pivoting movement without requiring forward pushing motion, thereby maintaining a stable fixed hand position on the handle while keeping the structure relatively simple.
2Reliability
If both locking lever and operating lever are pressed simultaneously, then safety is ensured, but the operation becomes uncomfortable and not intuitive
Solution Approach 1:
The locking lever must be operated first to unlock the operating lever before the operating lever can be actuated. This preliminary action sequence ensures safety by preventing accidental activation while making the operation more intuitive, as the operator naturally follows the sequential unlocking-activating pattern rather than attempting to press both levers simultaneously.
3Device complexity
If the thumb is used to operate the locking lever with parallel arrangement, then the structure is simple, but the thumb slips off during pivoting movement
Solution Approach 1:
By arranging the locking lever at an asymmetric angle of 10° to 60° toward the rear end of the handle rather than parallel to the longitudinal axis, the pivoting movement of the thumb during operation is optimized. This angular arrangement ensures the thumb maintains stable contact with the locking lever throughout the pivoting motion, preventing slippage while keeping the configuration relatively simple.
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
Enables ergonomic and intuitive operation of hand-held work devices, allowing the operator to maintain a firm grip while easily activating the locking and actuating levers, improving usability for both right- and left-handed users.
Implementation Method 1
a spring unit for the locking lever interacts with a contour on the locking lever, wherein the contour extends over an angular section around the rotational axis of the locking lever and has a lower section formed in the direction of the rotational axis of the locking lever. In particular, it is provided that the spring unit, resting in the lower section of the contour, preloads the locking lever toward the locked position.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a hand-held tool with a tool (3). The tool comprises a handle (26), the handle (26) having a longitudinal axis (18). The locking lever (5) is pivotally mounted about a pivot axis (8). The locking lever (5) locks the actuating lever (4) in a locked position (10) and releases the actuating lever for actuation in at least one operating position (11, 11'). The longitudinal axis (18) of the handle (26) forms an angle (α) with the pivot axis (8) of the locking lever (5) perpendicular to the longitudinal plane (27) in the viewing direction, the angle (α) being in a range of 10° to 60°.