Hedge Shears with Planetary Gear Transmission
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Solution Overview
Problem
Conventional hedge shears require excessive user effort due to constant cutting power throughout the cutting process, and the integration of metal transmission means in blades makes them expensive and prone to branch interference.
Innovation Solution
A cutting tool design featuring pivotally attached blades with a planetary gear system, where toothed transmission parts engage to increase cutting power progressively as the blades move from open to closed positions, eliminating the need for metal transmission within the blades and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If transmission means are formed directly in the blade using metal material, then the cutting power can be increased, but the manufacturing cost increases and branches can enter between the teeth during operation
Solution Approach 1:
The patent replaces expensive metal transmission means with cheaper plastic transmission means. The plastic transmission means are formed as integral parts of the handles through injection molding, eliminating the need for separate metal components. This significantly reduces manufacturing cost while maintaining functional effectiveness.
Solution Approach 2:
The patent substitutes metal mechanical transmission components with plastic transmission means. The plastic transmission means achieve the same mechanical advantage and power transmission function as metal components but through a different material system that is easier and cheaper to manufacture.
2Power
If transmission means are formed directly in the blade using metal material, then the cutting power can be increased, but branches can enter between the teeth of the transmission means during operation
Solution Approach 1:
The patent replaces expensive metal transmission means with cheaper plastic transmission means. The plastic transmission means are formed as integral parts of the handles through injection molding, eliminating the need for separate metal components. This significantly reduces manufacturing cost while maintaining functional effectiveness.
3Device complexity
If conventional constant cutting power is used throughout the cutting movement, then the structure is simple, but excessive user effort is required and cutting efficiency is low
Solution Approach 1:
The patent implements a dynamic cutting power transmission system where the cutting power varies during the cutting movement. The transmission means are designed to provide progressive power transmission, delivering maximum cutting force at the end of the cutting stroke where it is most needed, while requiring less force during the initial phase when branches are being gathered. This dynamic power distribution significantly improves cutting efficiency and reduces user effort.
4Device complexity
If transmission means are formed directly in the blade, then the structure is compact, but they are made of expensive metal and are laborious to manufacture
Solution Approach 1:
The patent merges the transmission means with the handles by forming them as integral parts through injection molding. The transmission means are no longer separate components that need to be manufactured and assembled, but are instead molded directly into the handle structure. This eliminates additional manufacturing steps and reduces assembly complexity.
Solution Approach 2:
The patent replaces expensive metal transmission means with cheaper plastic transmission means. The plastic transmission means are formed as integral parts of the handles through injection molding, eliminating the need for separate metal components. This significantly reduces manufacturing cost while maintaining functional effectiveness.
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 progressive power transmission increases cutting force by two- to threefold, reducing user effort and manufacturing costs by using less expensive materials like plastic for the transmission components.
Implementation Method 1
a first cutting blade (6) pivotally attached to a first handle (2) at a first pivot-point (40) and a second cutting blade (8) pivotally attached to a second handle (4) at a second pivot-point (42), wherein the cutting blades (6, 8) are further attached to one another at a third pivot-point (10)
Implementation Method 2
The shape of the toothed transmission parts (12, 14, 16, 18, 20, 22) as well as their mutual arrangement together with the pivot-points (10, 40, 42) enable a power transmission from the handles (2, 4) to the cutting blades (6, 8)
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a cutting tool comprising a first handle (2), a second handle (4), a first cutting blade (6) attached to the first handle (2) at a first pivot point (40), as well as a second cutting blade (8) attached to the second handle (4) at a second pivot point (42), the first and the second cutting blades (6, 8) being engaged with one another at a pivot point (10) such that the first and the second cutting blades (6, 8) are movable in a scissor-like manner between an open position and a closed position in response to a relative rotational movement of the first and the second handles (2, 4). The invention is characterized in that the first handle (2) comprises a first toothed transmission part (12) and the second handle (4) comprises a second toothed transmission part (14), the first and the second toothed transmission parts (12, 14) being arranged to be engaged with one another.