Pruning Shear Drive Mechanism for Angular Adjustment
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Solution Overview
Problem
Existing pruning shears face challenges in adjusting the angle of the cutting head relative to the handle without altering the width of the cutting jaw, with existing solutions either being complex, expensive, or difficult to reassemble for maintenance.
Innovation Solution
A drive mechanism incorporating a second wheel with guide surfaces and an upper line that adjusts by winding on and off specific guide surfaces to maintain constant length, allowing for angular adjustment of the cutting head without altering the drive line length, thus simplifying the adjustment process and eliminating the need for locking mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the cutting head is adjusted relative to the elongated handle by winding the drive line on the drive wheel, then the angular position of the cutting head can be changed, but the drive line length changes causing the cutting jaw width to alter and requiring additional work to restore maximum size
Solution Approach 1:
The drive line is divided into two separate lines: a first line connected to the drive wheel for power transmission, and a second line (upper line) connected to the second wheel for angular adjustment. This segmentation allows independent adjustment of the cutting head angle without affecting the drive line length and cutting jaw width.
Solution Approach 2:
The second wheel acts as an intermediary mechanism between the cutting head and the drive mechanism. It provides a dedicated adjustment function for angular position without interfering with the primary drive function, thereby eliminating the need to release and restore the drive line length.
2Manufacturing precision
If a complex drive mechanism is used to adjust the cutting head angle without changing the drive line length, then the cutting jaw width remains constant, but the device complexity increases and becomes expensive to manufacture
Solution Approach 1:
The drive mechanism is segmented into two independent subsystems: one for power transmission (drive wheel and drive line) and one for angular adjustment (second wheel and upper line). This segmentation maintains cutting jaw width consistency while keeping the overall mechanism simple and cost-effective.
Solution Approach 2:
The second wheel serves multiple functions: it enables angular adjustment of the cutting head, maintains constant upper line length during adjustment, and prevents unintended return to straight position through its guide surface geometry. This multi-functionality reduces the need for additional complex components.
3Stability of the object's composition
If the drive mechanism is made complex to prevent unintended return to straight position, then adjustment stability improves, but the ease of repair and reassembly deteriorates
Solution Approach 1:
The mechanism is divided into modular components (drive wheel, second wheel, counterparts) that can be independently assembled and disassembled. This segmentation maintains adjustment stability while facilitating easy repair and reassembly.
Solution Approach 2:
The guide surfaces on the second wheel and counterparts are designed to automatically maintain the upper line in the correct position and prevent unintended return to straight position through their geometric configuration, eliminating the need for additional locking mechanisms or complex stabilization devices.
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
The invention relates to pruning shears comprising a cutting head (12) with a spring-loaded blade (18) acting in cooperation with a counter blade (20), a drive mechanism (16) connected to the cutting head (12), and an elongated handle (14) connected to the drive mechanism (16). The drive mechanism comprises a first and a second counterpart (32, 34), optionally rotating with respect to one another about an axis (36), allowing the cutting head (12) to be adjusted with respect to the elongated handle (14), and an upper line arrangement allowing the blade (18) to be turned about a hinge point (19) and the cutting head to be adjusted in such a manner that the blade (18) does not rotate about the hinge point (19).