Pole Hedge Trimmer Drive Shaft Safety Lock
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Solution Overview
Problem
Motor-driven tools like pole hedge trimmers and saws pose a risk of accidental activation when the cutting unit is folded back, potentially injuring the operator, as existing designs lack a mechanism to prevent activation in this position.
Innovation Solution
A device with a turnable connection system using conical gear wheels and a spring-loaded mechanism that blocks the drive shaft when the cutting unit is in the folded position, ensuring it cannot be activated unless turned to a working position, eliminating the risk of accidental start-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the cutting unit is made turnable and foldable to a transport position, then the adaptability and ease of transport are improved, but the safety of the operator deteriorates due to risk of accidental activation
Solution Approach 1:
The patent applies preliminary anti-action by implementing a mechanical blocking mechanism that prevents the drive shaft from rotating when the cutting unit is in the folded transport position. The blockable drive shaft arrangement creates a preliminary counter-force that stops the cutting elements from being activated, directly counteracting the potential harmful effect of accidental activation while preserving the foldable design's adaptability benefits
2Object-affected harmful factors
If a safety mechanism is added to prevent accidental activation, then the operator safety is improved, but the device complexity increases
Solution Approach 1:
The patent merges the safety function with the existing mechanical structures of the pole hedge trimmer. The blocking mechanism is integrated into the drive shaft and cutting unit assembly, using components that are already part of the tool's basic structure. This combining approach achieves accidental activation prevention without adding separate, complex safety systems, thus improving safety while minimizing the increase in device complexity
3Volume of moving object
If the cutting unit is folded back to transport position, then the loss of space and portability are improved, but the safety deteriorates due to potential contact with throttle control
Solution Approach 1:
The patent extracts the cutting unit from its operational position and folds it back to a compact transport position alongside the shaft tube. This extraction and repositioning achieves space savings and improved portability while the separate blocking mechanism ensures that even in this compact configuration, the cutting elements remain inactive and cannot be accidentally activated through throttle contact
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
Prevents accidental activation of the cutting unit when folded, enhancing operator safety and allowing for easy angular adjustment of the cutting area without the need for electrical components, suitable for various shaft tube lengths and as an accessory for bush cutters.
Implementation Method 1
A device with a conical gear wheel system and spring-loaded mechanism that blocks the drive shaft when the cutting unit is in the folded transport position
Implementation Method 2
A device with a conical gear wheel system and spring-loaded mechanism
Data Source
AI summary
A device for a motor driven tool such as a pole hedge trimmer, a pole saw or the like. The tool includes a drive unit that via a shaft tube is connected to a cutting unit. The cutting unit is turnably secured at the shaft tube by the device which is a turnable connection, wherein the cutting unit is movable between a range of at least two working positions and a transport position. The cutting unit is provided with one or several movable cutting elements and the tool is provided with locking structure for locking the movement of the cutting elements when the cutting unit is in the transport position.