Overlapping Screw Gear Structure for Compact Long Stroke
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Solution Overview
Problem
Existing helical gear designs for orthodontic applications face challenges in achieving a balance between compactness and stroke length, often compromising mechanical properties by using screws of significantly different diameters and complex thread configurations, which affect the efficiency and stability of the device.
Innovation Solution
The helical gear design features screws with threaded sections divided into multiple partial sections, allowing for axial insertion and overlap, with mating threads in the nut extending over a significant portion of their axial length, enabling a compact yet stable structure that enhances the stroke length and mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If one screw is designed with a significantly larger diameter than the other to achieve greater stroke, then the stroke length is improved, but the mechanical properties of the smaller screw are significantly worsened
Solution Approach 1:
The patent applies nesting by allowing the first screw to be inserted into the second screw axially, with their threaded sections overlapping by at least 50% of the axial dimension. This nested configuration enables both screws to share the mechanical load, preventing the smaller screw from bearing excessive stress while achieving extended stroke through the overlapping threaded sections that engage with a common nut.
2Volume of moving object
If the threaded sections are made shorter to reduce device size, then the compactness is improved, but the stroke length is reduced
Solution Approach 1:
The patent utilizes the axial dimension by allowing significant overlap (at least 50%) of the threaded sections of the two screws. This axial overlapping arrangement enables the threaded sections to engage with a common nut in a way that extends the effective stroke length without proportionally increasing the overall device volume, achieving a favorable size-to-stroke ratio.
3Stability of the object's composition
If the screws are inserted axially into one another with significant overlap, then the compactness and stability are improved, but the complexity of thread configuration increases
Solution Approach 1:
The patent segments the threaded sections of both screws into multiple partial sections (at least two each) arranged axially. This segmentation allows the screws to be inserted into one another with overlapping threaded sections that engage with corresponding partial sections in the common nut, distributing the mechanical interaction across multiple segments and enhancing stability while managing complexity through modular thread design.
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
This design achieves a large stroke with a very compact form factor and improved stability, suitable for orthodontic applications such as palatal expansion, by allowing screws to overlap significantly and providing a continuous thread configuration within the nut, thereby optimizing the mechanical properties and functionality of the device.
Implementation Method 1
a first screw (1) with a right-hand thread (15) and a second screw (2) with a left-hand thread (25), and a common nut (3), in which the first and second screws (1, 2) can be screwed into the mating threads from opposite sides of the nut (3)
Data Source
Figure 1~3
Figure 4~6
Figure 7~8
AI summary
The invention relates to a screw gear comprising a first and a second screw (1, 2), the first screw (1) of which has a threaded section (13) with a right-hand side thread (15) and the second screw (2) of which has a threaded section (23) with a left-hand side screw (25), and a common nut (3), which has two mating threads (5, 6). The threaded sections (13, 23) of the first and second screw (1, 2) have at least two respective sub-sections (13a, 13b; 23a, 23b), the outer surfaces of which form circumferential parts of circular cylindrical lateral surfaces provided with the right-hand side or left-hand side thread (15, 25). At least one of the screws (1, 2) has a slot (16, 26) starting from the base end (12, 22) of the screw in the region of the longitudinal central axis (17, 27) of the screw, said slot separating the sub-sections (13a, 13b; 23a, 23b), wherein the first and second screws (1, 2), the base ends (12, 22) of which are to be oriented towards each other, can be plugged axially into each other.