Telescopic Pruner Pull-Cord Routing With Internal Pulleys
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Solution Overview
Problem
Existing telescopic hand tools with multiple tubes often have visible and externally guided pull cords, which can be cumbersome and prone to friction losses, making operation less efficient and exposed to damage.
Innovation Solution
A telescopic hand tool design with a pull cord arranged substantially inside the tubes, utilizing deflection and guiding pulleys to redirect the pulling means, minimizing visible exposure and reducing friction through internal guidance and optimized length adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pull cord is arranged externally and guided in grooves on the tube surface, then the pull cord is easily accessible and simple to operate, but the pull cord is exposed to damage, prone to friction losses, and visually cumbersome
Solution Approach 1:
The pull cord is nested within the hollow interior of the telescopic tubes, running through the internal cavity rather than externally. This nesting arrangement protects the pull cord from external damage while keeping it accessible through the handle assembly, resolving the contradiction between protection and accessibility.
Solution Approach 2:
Deflection pulleys are introduced as intermediary elements to redirect the pull cord force from the handle to the telescopic sections. These pulleys enable the pull cord to operate effectively from an internal position without requiring external routing, maintaining ease of operation while achieving protection.
2Loss of energy
If the pull cord is routed externally along the tube, then the cord is easily accessible for operation, but friction losses increase and the tool appears cumbersome
Solution Approach 1:
The pull cord is nested within the tube interior, eliminating contact with external grooves or guides that would create friction. This internal routing reduces energy loss while simultaneously simplifying the external appearance by hiding the cord and its routing mechanisms.
3Length of moving object
If three tubes are used to achieve small minimum length and large maximum length, then the telescopic range is improved, but the pull cord becomes more complex and more prone to external damage
Solution Approach 1:
The pull cord runs through the hollow interior of all three nested tubes, protecting it from external damage regardless of the number of telescopic sections. This internal routing maintains pull cord durability while enabling the three-tube configuration to achieve its full telescopic range potential.
4Loss of energy
If the pull cord is arranged inside the tubes, then the pull cord is protected from damage and friction losses are reduced, but the routing becomes more complex requiring deflection pulleys
Solution Approach 1:
Deflection pulleys serve as intermediary elements that manage the complexity of internal routing by providing smooth redirection points for the pull cord. These pulleys are positioned at strategic locations within the tube assembly, enabling efficient force transmission while containing the routing complexity within the protected internal volume.
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 design provides a more efficient and protected operation with reduced friction losses, allowing easy handling and minimizing exposure of the pull cord to damage, while maintaining a compact and extendable structure.
Implementation Method 1
a number of deflection pulleys arranged at the back ends of the tubes and at the front ends of the outer tube and the intermediate tube, wherein the deflection pulleys are provided for redirecting the pulling means
Implementation Method 2
a hoist pulley slidable within the inner tube and connected to the tool head by a rod, a cord or the like, wherein the hoist pulley is provided for redirecting the pulling means
Data Source
Figure 1~5
Figure 6~9
AI summary
The present invention relates to a telescopic hand tool (10), in particular a telescopic pruner. The telescopic hand tool (10) comprises an outer tube (12), at least one intermediate tube (14) slidable within the outer tube (12) and an inner tube (16) slidable within the intermediate tube (14). At least one tool head (18) is connected or connectable to the front end of the inner tube (16). A back handle (28) is detachably arranged at the back end of the outer tube (12). A pull sleeve (22) is slidable along the outer tube (12). A pulling means (30) has a flat cross-section and is arranged substantially inside the tubes (12, 14, 16), wherein the one end portion of the pulling means (30) is connected to a fixation point (52) at the front end of the outer tube (12), while the other end portion of the pulling means (30) is connected to the pull sleeve (22). A further pulling means (48) extends between a joint (50) arranged at the pulling means (30) and the back handle (28). A number of deflection pulleys (32, 34, 36) is arranged at the back ends of the tubes (12, 14, 16) and at the front ends of the outer tube (12) and the intermediate tube (14), wherein the deflection pulleys (32, 34, 36) are provided for redirecting the pulling means (30). A hoist pulley is slidable within the inner tube (16) and connected to the tool head (18) by a rod, a cord or the like, wherein the hoist pulley is provided for redirecting the pulling means (30). An elongated groove (40) is formed in the outer side of the outer tube (12) and extending parallel to said outer tube (12), wherein first and second portions of the pulling means (30) are arranged one to another and guided within the groove (40), and wherein the first portion of the pulling means (30) is connected to the pull sleeve (22) by a fixation (46) .