Pruning Tool Reverse Pulley System for Variable Branch Diameter Cutting
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Solution Overview
Problem
Existing pruning tools require adjustment of pulling force and distance for cutting branches of varying diameters, which can be cumbersome and inefficient, especially when dealing with thicker branches.
Innovation Solution
A pruning tool with an elongated handle and a movable working device, featuring a reverse pulley system that allows the pulling member to be detachably fixed to a stop element for cutting thinner branches and directly to the actuation handle for cutting thicker branches, adjusting the pulling force and distance accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a reverse pulley system with detachable pulling member is used, then the pulling force and distance can be adjusted for different branch sizes, but the device complexity increases
Solution Approach 1:
The pulling member is designed to be detachably attachable to different positions (stop element or actuation handle) depending on the cutting task. This dynamic reconfiguration allows the same device to adapt between two different mechanical advantage configurations: one for thin branches and another for thick branches, providing versatility without requiring multiple complete tools.
Solution Approach 2:
The pulling member is divided into segments that can be detachably connected to different attachment points. The pulling member can be detached from the stop element and reattached to the actuation handle, or vice versa. This segmentation enables flexible reconfiguration of the force transmission path to match different cutting requirements.
2Force
If multiple pulleys and long pulling members are used to achieve high cutting power, then the cutting force increases, but the pulling way becomes independent from branch diameter requiring full movement range
Solution Approach 1:
The system dynamically adjusts the mechanical advantage ratio by reconfiguring the pulling member attachment point. When attached to the stop element, it provides higher mechanical advantage for thick branches; when attached to the actuation handle, it provides lower mechanical advantage for thin branches. This dynamic adjustment allows the pulling distance to be optimized for each specific cutting task rather than requiring the full range for all situations.
Solution Approach 2:
The mechanical advantage parameter is changed by altering the attachment configuration of the pulling member. The system switches between two discrete parameter states: a high mechanical advantage state for thick branches and a low mechanical advantage state for thin branches. This parameter change allows the operator to match the pulling distance and force characteristics to the specific branch diameter being cut.
3Ease of operation
If the pulling member is detachably fixed to the stop element, then the pulling way is reduced for thin branches, but the device cannot provide sufficient pulling force for thick branches
Solution Approach 1:
The system provides dynamic reconfigurability where the pulling member can be detached from the stop element and reattached to the actuation handle when thicker branches need to be cut. Conversely, for thin branches, the pulling member is attached to the stop element to reduce pulling way. This dynamic switching allows the operator to optimize the force-distance characteristics according to the specific cutting task.
Solution Approach 2:
The same pulling member and attachment mechanism serve multiple functions: it can be attached to the stop element for thin branch cutting with reduced pulling way, or detached and reattached to the actuation handle for thick branch cutting with increased pulling force. This multi-functionality eliminates the need for separate tools for different branch sizes.
4Force
If the pulling member is detachably fixed to the actuation handle, then the pulling force is increased for thick branches, but the pulling way becomes too long for thin branches
Solution Approach 1:
The system allows dynamic reconfiguration where the pulling member can be detached from the actuation handle and reattached to the stop element when thinner branches need to be cut. This reduces the pulling way to an appropriate length. The dynamic switching between attachment points allows optimization of the force-distance relationship for each specific cutting scenario.
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
Enables easy adjustment of pulling force and distance, allowing for efficient cutting of branches of varying sizes with reduced operator effort, as the same actuating force can cut both thinner and thicker branches with minimal effort.
Implementation Method 1
The actuation handle is coupled to the working device by means of a pulling member in order to transmit actuating forces on the working device
Implementation Method 2
Known pruning tools comprise different pulley block systems to transmit the pulling force to the working device. In order to achieve high cutting power with less effort for the operator, often several pulleys and long pulling members are needed.
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5B
AI summary
The invention is directed to a pruning tool (100, 200, 300, 400), in particular a branch pruner, a lopper or a secateur, comprising an elongated handle (102, 202, 302, 402), whereby a movable working device (106) is arranged at a first end portion (104) of the handle, further comprising an actuation handle (114, 214, 314, 414) being arranged on the elongated handle (102, 202, 302, 402) and being movable along the elongated handle (102, 202, 302, 402) between a first position and a second position, further comprising a stop element (116, 216, 316, 416) being fixed on the handle (102, 202, 302, 402) in order to limit the movement of the actuation handle (114, 214, 314, 414) in the direction of the working device (106), whereby the actuation handle (114, 214, 314, 414) is coupled to the working device (106) by means of a pulling member (122, 222, 322, 422) in order to transmit actuating forces on the working device (106), and whereby in order to perform a first cutting action a first end (124, 224, 324, 424) of the pulling member (122, 222, 322, 422) is detachable fixable to the stop element (116, 216, 316, 416) and whereby in order to perform a second cutting action the first end (124, 224, 324, 424) of the pulling member (122, 222, 322, 422) is detachable fixable to the actuation handle (114, 214, 314, 414).