Blocking Lever Handle Geometry for Intuitive One-Handed Actuation
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Solution Overview
Problem
Existing handheld work apparatuses require operators to actuate both the blocking lever and the actuating lever simultaneously, which can be inconvenient and not very intuitive, often necessitating a release of the handle grip.
Innovation Solution
The handheld work apparatus is designed with a handle and a blocking lever that can be pivoted by the thumb within the natural pivot movement, allowing the actuating lever to be operated with the index finger or another free finger without needing to slide the thumb forward.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the blocking lever and actuating lever are arranged to be pressed simultaneously with one hand, then the device can be operated with one hand, but the operation becomes inconvenient and not intuitive, requiring release of handle grip
Solution Approach 1:
The patent divides the operation sequence into two distinct steps: first pressing the blocking lever with the thumb to unlock it, then pressing the actuating lever with the index finger or another free finger. This segmentation allows each finger to perform its function independently without requiring simultaneous coordination, making the operation more intuitive and comfortable while maintaining one-handed operation capability.
2Device complexity
If the rotational axis of the blocking lever is arranged parallel to the longitudinal axis of the handle, then the structure is simplified, but the thumb slides off the blocking lever during pivot movement, requiring longitudinal thumb movement and release of firm grip
Solution Approach 1:
The patent introduces an asymmetric angular relationship between the rotational axis of the blocking lever and the longitudinal axis of the handle, with the angle in the range of 10° to 60°. This asymmetric arrangement ensures that during thumb pivot movement, the thumb remains engaged with the blocking lever surface, preventing sliding off while maintaining a firm grip on the handle. The angular offset creates a geometric constraint that guides the thumb movement along the lever surface.
Data Source
AI summary
A handheld work apparatus includes a work tool. The work apparatus defines a longitudinal plane and includes a handle having a longitudinal axis. The blocking lever is mounted so as to be pivotable about a rotational axis. The blocking lever blocks the actuating lever in a blocking or disable position and enables the actuating lever for actuation in at least one operating enable position. In the direction of view perpendicular to the longitudinal plane, the longitudinal axis of the handle and the rotational axis of the blocking lever conjointly define an angle (α). The angle (α) lies in a range of from 10° to 60°.