Coaxial Crown-Gear Gearbox With Sliding Cursor for Compact Reliability
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Solution Overview
Problem
Existing gearboxes with coaxial wheels are bulky, heavy, complex, and prone to dirt ingress, leading to reliability issues.
Innovation Solution
A gearbox design with coaxial conical front toothed wheels featuring a cursor mechanism that allows for compact, simple construction and reliable operation, enabling easy integration into bicycle hubs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gear mechanisms are used to achieve coaxial wheel arrangement, then gear transmission function is realized, but the gearbox becomes bulky and heavy
Solution Approach 1:
The patent implements nesting by placing the cursor mechanism inside the hollow interior of the driven wheel, and positioning the driving wheel within the same spatial envelope. The cursor slides within the driven wheel's interior space, and both wheels share a common axial space, effectively nesting components within each other to minimize overall gearbox volume and weight.
Solution Approach 2:
The patent transitions from traditional parallel shaft arrangements to a coaxial configuration where both driving and driven wheels share the same axis. This dimensional reorganization allows the cursor to slide radially inward and outward along the common axis, enabling gear engagement/disengagement in a compact radial space rather than requiring extended axial space.
2Reliability
If conventional gear mechanisms are used to achieve coaxial wheel arrangement, then gear transmission function is realized, but the structure becomes complex
Solution Approach 1:
The patent merges the cursor function with the gear engagement mechanism. The cursor itself serves as both the sliding element for ratio change and the carrier for the small gear. The crown gears are integrated directly into the wheel perimeters, eliminating separate engagement mechanisms. This consolidation reduces the number of independent components and simplifies the overall structure.
Solution Approach 2:
The cursor performs multiple functions: it serves as the sliding element for gear engagement/disengagement, as the carrier for the small gear, and as a structural connector between the driving and driven wheels. The conical surfaces on both wheels provide both structural support and the geometric basis for the cursor's angular positioning, combining multiple functions into unified components.
3Reliability
If conventional gear mechanisms are used, then gear transmission is achieved, but protection from dirt becomes difficult leading to reliability decrease
Solution Approach 1:
The cursor and small gear are nested within the hollow interior of the driven wheel, creating a enclosed space that is protected from external contaminants. The driving wheel is positioned within the same enclosed spatial envelope, and the crown gears engage in this protected interior space, effectively shielding the gear transmission from dirt and debris.
4Reliability
If conventional gear mechanisms are used, then gear transmission function is achieved, but the gearbox becomes bulky
Solution Approach 1:
The patent implements nesting by placing the cursor mechanism inside the hollow interior of the driven wheel, and positioning the driving wheel within the same spatial envelope. The cursor slides within the driven wheel's interior space, and both wheels share a common axial space, effectively nesting components within each other to minimize overall gearbox volume and weight.
Solution Approach 2:
The patent transitions from traditional parallel shaft arrangements to a coaxial configuration where both driving and driven wheels share the same axis. This dimensional reorganization allows the cursor to slide radially inward and outward along the common axis, enabling gear engagement/disengagement in a compact radial space rather than requiring extended axial space.
Data Source
AI summary
A gearbox (10) is provided and includes a driving wheel (4) and a driven wheel (3) rotating on a common axis (13) and a cursor (9) arranged transversally to the axis (13) and sliding with respect to it. The wheels (4, 3) have crown gears (5A, 5B) arranged on different diameters of the drive (4) and driven wheels (3). The crown gears (5A, 5B) have teeth protruding from facing surfaces (21, 22) of the wheels (4, 3). The cursor (9) has two gears (7A, 7B) arranged at its ends, rotating around the axis (19) of the cursor (9) and configured to transmit motion from the driving wheel (4) to the driven wheel (3), engaging each gear (7A, 7B) in respective crown gears (5A, 5B) of the driving wheels (4) and driven wheels (3). The cursor (9) slides inside a seat (15) made in the axis (13).