Rotary-Knob Hinge Locking for Stable Tree Trimmer Angle Adjustment
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Solution Overview
Problem
Existing hinges for hand tools, particularly tree trimmers, suffer from angle instability due to plastic deformation under pressure, leading to loosening and inadequate fixation.
Innovation Solution
A hinge design featuring a rotary knob and push element mechanism, where rotating the knob linearly moves the push element against a contact surface, secured by complementary threads and optionally a spring element, ensuring stable locking and adjustable stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a plastic hinge is used for adjustable angle fixation, then the hinge can be easily adjusted and fixed, but the plastic deforms under pressure causing the hinge to loosen and lose stability
Solution Approach 1:
The hinge combines plastic components (first hinge part, second hinge part) with a metal spring element to create a composite structure. The plastic provides ease of adjustment and molding complexity, while the metal spring provides elastic force and stability under pressure, preventing the loosening problem of pure plastic hinges.
Solution Approach 2:
The spring element is pre-loaded to exert a continuous counteracting force against the contact surface between hinge parts. This preliminary elastic force compensates for the plastic deformation that would otherwise cause loosening, maintaining stable angle fixation without requiring additional locking mechanisms.
2Reliability
If a screw is used to clamp the hinge, then the hinge can be fixed stably, but the structure becomes more complex and requires additional components
Solution Approach 1:
The spring element serves multiple functions simultaneously: it provides the locking force to prevent loosening, acts as a buffer against plastic deformation, and enables angle adjustment through its elastic compression and expansion. This self-service mechanism eliminates the need for separate screws or clamps, reducing structural complexity while maintaining stability.
Solution Approach 2:
The invention extracts the essential function of angle fixation and stabilization from complex screw-clamp mechanisms, achieving the same stability through a simpler spring-based elastic connection between the first and second hinge parts.
3Adaptability or versatility
If the hinge angle is adjustable, then the user can optimize the working position, but the hinge may become loose over time due to plastic flow under pressure
Solution Approach 1:
The spring element's elastic properties allow it to dynamically adapt to different hinge angles while maintaining stable fixation. When the user adjusts the angle, the spring compresses or expands accordingly, providing continuous stabilizing force that prevents loosening regardless of the selected angle position.
Solution Approach 2:
The spring element is positioned to preemptively counteract the plastic deformation forces that occur during angle adjustment and use. By providing continuous elastic support before loosening can occur, the spring ensures long-term angle fixation stability while preserving adjustability.
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 stable and adjustable hinge that maintains the desired angle, preventing loosening and enhancing user control through mechanical force transmission.
Implementation Method 1
the rotary knob and the push element are coupled via at least one pair of complementary threads, so that the rotation of the rotary knob results in the linear movement of the push element
Implementation Method 2
at least one spring element is arranged between the push element and the contact surface of the second hinge part
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention relates to a hinge (10) for a hand tool, in particular for a tree trimmer or the like. The hinge (10) comprises a first hinge part (12) including a first half-shell (16) and a second half-shell (18), a second hinge part (14) pivotable relative to the first hinge part (12) around a swivel axis (54) of the hinge (10) and a rotary knob (20) arranged rotatable at the first hinge part (12) and rotatable around the swivel axis (54). A push element (22) is linearly moveable along the swivel axis (54) inside the first hinge part (12). The push element (22) is pressed or pressable against a contact surface (42) of the second hinge part (14) by rotating the rotary knob (20), so that the hinge (10) is locked or at least rough-running.