Vehicle Freewheel Helical Engagement for Low-Wear Torque Transfer
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Solution Overview
Problem
Existing freewheels in vehicles, particularly electric bikes, face issues with wear and noise due to tooth engagement mechanisms, and lack robustness in torque transfer management.
Innovation Solution
A freewheel design incorporating a helical mechanism with a friction element and a return element, allowing for precise translational displacement of the freewheel element to engage or disengage gear cogs, utilizing a thread or magnetic force for efficient torque transfer and low-wear operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring-loaded gear cog engagement mechanism is used, then the freewheel can interrupt torque transfer, but the teeth of the sawtooth cog sliding against each other cause wear and noise
Solution Approach 1:
The patent replaces the traditional mechanical tooth engagement system with a friction-based system. The friction element presses against the shaft to create friction closure, which actuates the helical mechanism to engage or disengage the gear cogs. This substitution eliminates the sliding contact between gear teeth, thereby reducing wear and noise while maintaining reliable torque transfer interruption.
Solution Approach 2:
The friction element serves as an intermediary between the shaft rotation and the gear cog engagement. Instead of the gear teeth directly interacting, the friction element mediates the force transfer through friction, which then actuates the helical mechanism. This intermediary approach allows for controlled engagement without direct tooth sliding, reducing harmful wear and noise.
2Object-generated harmful factors
If a helical mechanism with friction element is used, then wear and noise are reduced, but the device complexity increases
Solution Approach 1:
The patent combines multiple functions into integrated components. The friction element is axially displaceably arranged on the shaft and also serves as part of the actuation mechanism for the helical mechanism. The helical mechanism itself is formed by interlocking helix-shaped elements on the freewheel element and friction element, merging the engagement and actuation functions into a unified structure that reduces overall system complexity despite the advanced mechanism.
3Reliability
If the gear cog engagement is forced by the helical mechanism, then undesired slipping is prevented, but the manufacturing precision requirements increase
Solution Approach 1:
The patent replaces precision-dependent mechanical tooth alignment with a friction-based actuation system. The friction element creates friction closure that actuates the helical mechanism, which in turn engages the gear cogs. This substitution reduces the need for extremely precise manufacturing of the gear tooth interfaces, as the engagement is driven by the controlled friction-based actuation rather than relying solely on precise manufacturing tolerances.
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 achieves a robust, low-wear, and low-noise freewheel operation with rapid re-engagement capabilities, preventing undesired slipping and ensuring reliable torque transfer.
Implementation Method 1
a predetermined friction closure is formed between the second shaft and the friction element in the circumferential direction of the second shaft
Implementation Method 2
The freewheel element and the friction element are coupled to each other by means of a helical mechanism. The helical mechanism is in this case configured to effect a translational displacement of the freewheel element and the friction element relative to each another when the freewheel element and friction element rotate relative to each other
Data Source
AI summary
A freewheel of a vehicle, in particular a two-wheeler, includes (i) a first shaft, (ii) a second shaft having a first gear cog, (iii) a freewheel element having a second gear cog, and (iv) a friction element. The first gear cog and the second gear cog are configured to, when engaged with each other, effect a torque transfer between the second shaft and the freewheel element. The freewheel element is arranged to be displaceable in an axial direction on the first shaft. The freewheel element is arranged to be non-rotatable relative to the first shaft in the circumferential direction. The freewheel element and the friction element are connected to one another by way of a helical mechanism which is configured to effect a translational displacement of the freewheel element and the friction element relative to one another when the freewheel element and friction element rotate relative to one another.