Curved Handle Lever for Ergonomic One-Handed Tool Control

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing hand-held, motor-driven work devices lack ergonomic and flexible control elements for convenient one-handed operation, particularly in gardening and forestry tools.

Innovation Solution

The operating device features a control element with a curved and/or angled finger contact area that aligns optimally with the user's finger position, allowing pivoting movement perpendicular or at an angle to the handle shaft, combined with a pivot axis design that facilitates easy operation using the thumb or index finger.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a conventional control element is used on hand-held work devices, then the device structure remains simple, but the ease of operation and user comfort deteriorate due to lack of ergonomic design

Engineering Contradiction:
Improveease of operationVSAvoiddevice complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The control element features a curved finger contact area that follows the natural contour of a user's finger, replacing straight or angular contact surfaces. This curved geometry allows the finger to rest comfortably along the control element's length, distributing pressure evenly and enabling ergonomic operation without increasing overall device complexity

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The control element incorporates a differentiated structure where only the finger contact area is curved and ergonomically shaped, while other portions of the control element maintain simpler geometries. This localized application of ergonomic design provides enhanced ease of operation at the critical interaction point without unnecessarily complicating the entire control mechanism

Inventive Principle:
Principle #3Local quality

2Ease of operation

If a control element with extended finger contact area is implemented, then user comfort improves, but the control element length increases

Engineering Contradiction:
Improveuser comfortVSAvoidcontrol element length
Core Design Contradiction:
Ease of operationVSLength of moving object

Solution Approach 1:

By curving the finger contact area to follow the finger's natural contour, the design effectively increases the usable contact length along the finger's axis without proportionally increasing the control element's physical length. The curved geometry allows a shorter control element to provide the same ergonomic benefit as a longer straight element would

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Ease of operation

If the pivot axis is positioned for optimal finger operation, then ease of operation improves, but the control element design becomes more complex

Engineering Contradiction:
Improveease of operationVSAvoidcontrol element design
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The pivot axis positioning and curved finger contact area are implemented as integrated local features of the control element, rather than as separate complex mechanisms. The curvature is confined to the finger contact zone, and the pivot axis is positioned to naturally support this curved geometry, creating an ergonomic solution that adds minimal complexity to the overall control element design

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3760025B1Operating device with handle and engine-driven working machine
Publication Date: 2025.12.17 ANDREAS STIHL AG & CO KG
  • EP3760025B1 patent drawingFigure 1~2
  • EP3760025B1 patent drawingFigure 3
  • EP3760025B1 patent drawingFigure 4~5

AI summary

1. Operating device with handle and motor-driven work device. 2.1. The invention relates to a hand-held, motor-driven work device and to an operating device therefor, wherein the operating device comprises a hand-gripping handle shaft (2), a control element receiving area (3) adjoining the handle shaft (2), and an operating unit acting on the operation of the device, which includes a control element that is movably held on the control element receiving area (3) for actuation by a finger of a hand gripping the handle shaft (2) and has a finger contact area (5) extending along an outer surface (3a) of the control element receiving area (3). 2.2.In the operating device according to the invention, the operating element is a pivoting operating lever (4) which is pivotably mounted on the operating element receiving area (3) about a pivot axis (SA), wherein the pivot axis (SA) extends with a principal directional component (HS) perpendicular to a longitudinal axis (LG) of the handle shaft (2), and wherein the finger contact area (5) has a curved and/or angled profile in a longitudinal extension along the outer side (3a) of the operating element receiving area (3) with a circumferential directional component (UK) and an axial directional component (AK). 2.3. Use e.g. for hand-held, battery-operated garden/forestry tools.