Worm Drive Assembly With Conical Bushing for Anti-Rotation Fit
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Solution Overview
Problem
Existing drives for movable objects, such as stairlifts, face issues with unintentional tipping, swiveling, twisting, wear-related uncontrolled rotation, and axial/radial misalignment of gear components, which compromise safety and compliance with safety regulations.
Innovation Solution
A drive mechanism featuring a worm shaft with conical raised sections, a conical bushing, and a worm gear with alternating teeth and gaps, which ensures a tight fit to prevent uncontrolled rotation and misalignment by engaging with the worm wheel, even in cases of mechanical wear or damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional worm shaft and worm gear components are used without additional protective features, then the drive mechanism is simple in structure, but the components are prone to unintentional rotation, wear-related misalignment, and loss of positional stability
Solution Approach 1:
The conical bushing is pre-installed on the worm shaft with conical raised sections that protrude into the worm gear's gaps. This preliminary configuration ensures that before any wear or damage occurs, the raised sections are already positioned to engage with the worm gear teeth, preventing unintentional rotation and maintaining axial/radial alignment from the outset
Solution Approach 2:
The conical bushing acts as an intermediary component between the worm shaft and the worm gear. It provides a stable mounting interface that prevents direct contact and wear between the worm shaft and housing, while the raised sections on the bushing serve as mediators that engage with the worm gear to prevent rotational slippage and maintain precise positioning
2Duration of action of stationary object
If the worm shaft and worm gear components are designed without wear compensation features, then manufacturing and assembly are simpler, but the components suffer from uncontrolled rotation and misalignment due to wear over time
Solution Approach 1:
The conical bushing with raised sections provides a protective mechanism that compensates for wear before it causes failure. As the worm shaft and gear wear over time, the raised sections maintain engagement with the gear teeth, cushioning against the effects of wear and preventing sudden loss of alignment or uncontrolled rotation that would otherwise occur after a certain service life
Solution Approach 2:
The conical shape of the bushing and raised sections allows for parameter changes in the engagement geometry as wear occurs. The conical geometry provides self-adjusting characteristics where the contact points between the raised sections and worm gear teeth can shift slightly to accommodate wear, maintaining functional alignment and preventing radial/axial misalignment even as the components age
Data Source
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AI summary
Drive for a movable object. The drive (1) has at least one worm shaft (5) into which at least one worm wheel (7) engages. The worm shaft (5) includes at least one raised section (4). At least one bushing (3) is arranged which bears against the worm shaft (5).