Ball-Coupled Worm Drive for High-Torque Low-Wear Transmission
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Solution Overview
Problem
Existing worm drives face issues with undue wear between the teeth of the gear and worm, particularly when attempting to transmit high torques, as previous solutions like using peripheral magnets or circulating balls either complicate manufacturing or fail to effectively handle shear forces and torque transmission.
Innovation Solution
A worm drive configuration featuring integrally formed cups on the worm wheel to hold balls, which are in rolling contact with a concavely tapering worm thread, allowing for a higher torque transmission with reduced shear forces and enhanced coupling through angled cup alignment, minimizing separation forces and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If peripheral magnets with balls are used to achieve rolling contact between worm and gear, then wear is reduced, but device complexity increases and reliability decreases due to magnet demagnetization risk
Solution Approach 1:
The patent extracts the balls from the conventional peripheral magnet configuration and relocates them to circulate through a tunnel formed through the worm. This removes the need for complex peripheral magnet assemblies on the gear wheel while maintaining the rolling contact benefit. The balls are now held by the worm structure itself rather than requiring separate magnet holdings on the gear.
Solution Approach 2:
The patent introduces a tunnel structure as an intermediary element that guides and contains the balls as they circulate between the worm and gear. This tunnel acts as a mediator that ensures proper ball positioning and circulation path without requiring complex magnet assemblies, simplifying the overall device while maintaining rolling contact functionality.
2Object-affected harmful factors
If balls are held by peripheral magnets to provide rolling contact, then wear is reduced, but reliability decreases due to shear forces on balls and magnet demagnetization
Solution Approach 1:
The patent removes the peripheral magnets from the system entirely and replaces them with a tunnel structure integrated into the worm. The balls are now contained and guided by the tunnel geometry rather than magnetic forces, eliminating the reliability issues associated with magnet demagnetization and shear forces on magnet-held balls.
Solution Approach 2:
The patent replaces the magnetic holding system with a purely mechanical tunnel structure. Instead of relying on magnetic forces to hold and guide the balls, the system uses the physical geometry of the tunnel to contain and direct ball circulation, providing more reliable mechanical containment without magnetic field dependencies.
3Device complexity
If conventional sliding contact is used between worm and gear, then device complexity is low, but undue wear occurs between teeth
Solution Approach 1:
The patent introduces balls as intermediary elements that circulate through a tunnel in the worm and make contact with both the worm and gear surfaces. These balls mediate the interaction between worm and gear, transforming the direct sliding contact into a rolling contact mechanism, thereby reducing wear while maintaining relative simplicity.
Solution Approach 2:
The patent employs spherical balls as the rolling contact elements. The spherical geometry of the balls enables rolling motion between the worm and gear surfaces, replacing sliding contact with rolling contact to reduce wear. The curved spherical surfaces are optimized for rolling interaction while maintaining structural simplicity.
4Power
If worms with longer arc contact are used (helical, hourglass, or globoid), then torque transmission is improved, but wear increases due to sliding contact over larger area
Solution Approach 1:
The patent uses circulating balls as intermediaries that contact both the extended arc surface of the globoid worm and the corresponding gear teeth. The balls transform the sliding contact that would occur over the extended arc into rolling contact, allowing the worm to maintain its torque-transmitting geometric features while eliminating the associated wear problems.
Solution Approach 2:
The patent employs spherical rolling elements that contact the curved surfaces of the globoid worm over an extended arc. The spherical geometry of the balls enables rolling motion along the curved worm surface, allowing the worm to maintain its complex torque-optimizing shape while the balls handle the contact in a rolling manner to reduce wear.
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 configuration enables efficient high-torque transmission with reduced wear and separation forces, allowing the worm wheel to handle extreme torque loads without additional bearings, while maintaining a robust and efficient mechanical coupling.
Implementation Method 1
the balls are in rolling contact with a concavely tapering worm thread
Data Source
Figure 1~1A
Figure 2
Figure 3
AI summary
A worm drive has a worm and a worm wheel. Meshing assemblies are formed about the worm wheel each comprising a ball and a cup receiving a portion of the ball. Each cup is orientated at an acute angle toward the worm drive relative to a periphery of the wheel. The worm presents a concavely tapering side profile complementing a peripheral portion of the worm wheel. Consequently portions of the balls mesh with the worm and are free to rotate and so reduce shear forces between the worm and the worm wheel in use.