Hand-held Tool Gearbox Bistable Spring Actuator
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Solution Overview
Problem
Existing hand-held power tools with switchable transmissions are difficult to operate, especially when wearing work gloves, and can be damaged due to improper gear shifting, leading to unstable gear positions.
Innovation Solution
A hand-held power tool with a bistable spring element as the actuating element, pivotably mounted between the switching element and the transmission housing, ensuring stable gear positions and reducing switching force, allowing for safe and reliable gear changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a sliding element is used for gear shifting, then the transmission can be switched between gears, but the operation becomes difficult especially when wearing work gloves
Solution Approach 1:
The patent changes the fundamental parameter of the actuating mechanism from a sliding element to a pivotable lever element. This parameter change transforms the shifting operation from linear sliding motion to rotational pivoting motion, which is significantly easier to operate with gloves on while maintaining the gear switching function.
Solution Approach 2:
The patent substitutes the sliding mechanical mechanism with a pivotable lever mechanism. The lever element pivots about an axis and engages different gear positions through rotational motion rather than linear sliding, replacing the problematic sliding element with a more operable mechanical system.
2Reliability
If a sliding element is used for gear shifting, then gear changes can be made, but improper shifting can damage the planetary gear
Solution Approach 1:
The patent incorporates a detent mechanism that provides tactile feedback and positional confirmation. The lever element engages with detent positions that correspond to correct gear settings, providing feedback to the operator and preventing improper shifting that could damage the planetary gear.
Solution Approach 2:
The detent mechanism acts as a preventive measure by physically guiding the lever element into correct gear positions before engagement. This beforehand cushioning prevents improper shifting from occurring in the first place, protecting the planetary gear from damage.
3Stability of the object's composition
If a sliding element is used for gear shifting, then the transmission can be switched, but the shifting position becomes unstable
Solution Approach 1:
The detent mechanism provides stable positional feedback by creating distinct engagement positions for the lever element. Each gear position is clearly defined by a detent engagement, ensuring stable gear positioning while maintaining smooth operation through the lever's natural pivoting motion.
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 bistable spring element enables smooth, comfortable, and safe gear shifting with reduced switching force, ensuring correct gear changes and a compact, grease-tight construction, while allowing for defined switching positions and accelerated gear changes.
Implementation Method 1
The actuating element is designed as a bistable spring element and is arranged at least in sections in the region between the switching element and the transmission housing
Data Source
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AI summary
In a hand-held power tool (100) with a switchable gearbox (118) for driving a drive shaft (120), which is arranged in a gearbox housing (190) and can be switched between at least a first gear and a second gear via a switching element (166), a pivotably mounted actuating element (150) is associated with the switching element (166), which is designed as a bistable spring element (400) and is arranged at least sectionally in the area between the switching element (166) and the gearbox housing (190), wherein the bistable spring element (400) can be actuated for gear switching and assumes a stable switching position in at least one switching position of the switching element (166), which is assigned to the first or second gear, and assumes an unstable position in an intermediate position of the switching element (166), which is arranged between the switching positions of the switching element (166) assigned to the first and second gear.