Hedge Trimmer Cutter Assembly Branch Removal
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Solution Overview
Problem
Hedge trimmers experience reduced workability due to branch tips getting caught in elongated holes, causing resistance during pruning operations.
Innovation Solution
A cutter assembly with overlapping lower and upper cutters, featuring elongated holes with first and second removal structures on their inner circumferential faces, which contact and remove branches that have entered, preventing them from getting caught and allowing smooth operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If elongated holes are formed on blades for weight reduction, then weight is reduced, but branch tips get caught in the holes causing resistance during operation
Solution Approach 1:
The patent extracts the harmful function of the elongated hole by adding a removal structure that actively removes branch tips before they can get caught. The removal structure (protrusion or groove) takes out the branch tip from the hole, preventing the harmful catching action while preserving the weight reduction benefit of the elongated hole itself.
Solution Approach 2:
The patent converts the potentially harmful effect of the elongated hole (branch tips getting caught) into a beneficial effect by using the hole's opening as a guide for the removal structure. The removal structure utilizes the hole's geometry to efficiently remove branch tips, transforming what could be a harmful catching mechanism into a useful branch removal feature.
2Weight of moving object
If elongated holes are formed on blades, then weight is reduced, but workability is reduced due to resistance from caught branches
Solution Approach 1:
The removal structure extracts branch tips from the elongated holes during the cutting operation. By actively removing the branches that would otherwise cause resistance, the system maintains high productivity despite the presence of elongated holes for weight reduction.
Solution Approach 2:
The removal structure is designed to automatically remove branch tips as part of the normal cutting operation. The protrusion or groove structure self-activates when a branch tip enters the elongated hole, requiring no additional manual intervention to prevent catching or improve workability.
3Ease of operation
If removal structure is added to elongated holes, then branch removal function is improved, but device complexity increases
Solution Approach 1:
The removal structure is applied locally only at the critical areas where branch tips enter the elongated holes, rather than modifying the entire cutter structure. This localized approach (protrusion or groove at specific positions on the elongated hole) provides effective branch removal while minimizing overall structural complexity.
Solution Approach 2:
The removal structure is segmented as a simple geometric feature (protrusion or groove) that can be independently added to the elongated hole without affecting the rest of the cutter design. This segmentation allows the removal function to be added with minimal impact on the overall device complexity.
Data Source
AI summary
A cutter assembly for a hedge trimmer comprises a lower cutter and an upper cutter overlap each other and slidable along their longitudinal direction. Each of the lower cutter and the upper cutter has a cutter main body and a plurality of cutting edges protruding laterally from the cutter main body. At least the cutter main body of the lower cutter has an elongated hole penetrating the cutter main body of the lower cutter in its thickness direction and extending along the longitudinal direction. The elongated hole is exposed to an outside of the cutter assembly. An area along the longitudinal direction on an inner circumferential face of the elongated hole has at least one removal structure having a function of contacting a branch that has entered the elongated hole, and thereby removing the branch from within the elongated hole.