Bicycle Single-Motor Power Unit With Torque-Limiting Pinion
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Solution Overview
Problem
Existing electric bicycles are often heavy, unsuitable for sport activities, require continuous device activation, and may cause back wheel spin on wet roads, leading to safety issues and limited customization options.
Innovation Solution
A single motor power unit integrated into a bicycle frame with a pinion dynamometric system and freely rotating bearings, allowing the motor to assist pedaling discreetly and safely, preventing axis breakage and gearhead wear, and enabling customizable operation through a central processor unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a traditional auxiliary engine is mounted onto a bicycle frame, then the bicycle gains motorized assistance for pedaling, but the bicycle becomes significantly heavier (over 15-20 kg addition)
Solution Approach 1:
The power unit is divided into separate functional components: a compact motor (200W), a planetary gearbox, a crankshaft pinion gearhead, and a propulsor pinion gearhead. This segmentation allows for a more space-efficient and weight-optimized design compared to traditional auxiliary engines, reducing the overall weight addition to approximately 1.8 kg while maintaining motorized assistance capability.
2Speed
If the pinion is always rotated when the engine is not running, then the engine can provide immediate assistance, but the pinion is subject to amortization and provides resistance
Solution Approach 1:
The system employs a dynamic engagement mechanism where the propulsor pinion gearhead is connected to the crankshaft pinion gearhead through a bearing that allows free rotation when the motor is not running. This dynamic design eliminates resistance and wear during idle periods while enabling immediate motor assistance when activated, resolving the contradiction between response speed and component durability.
3Ease of operation
If the engine keeps the pedals running in case of an accident or stuck pedals, then the pedals remain movable, but the axis may break due to excessive force
Solution Approach 1:
The system incorporates a dynamometric system with a spring mechanism that provides beforehand cushioning. When excessive force is applied to the pedals (such as during an accident or stuck pedal situation), the spring compresses to absorb the excess energy, preventing axis breakage while maintaining pedal mobility. This protective mechanism activates only under abnormal conditions, resolving the contradiction between ease of operation and structural strength.
4Ease of operation
If the back wheel is allowed to spin freely on wet roads, then the bicycle can move easily, but the user may be put in danger
Solution Approach 1:
The central processor unit continuously monitors wheel rotation and provides feedback control. When the back wheel spins freely on wet roads, the system detects this condition and can intervene by adjusting motor assistance or providing warnings to the user, thereby maintaining wheel mobility while preventing dangerous situations through active feedback control.
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 solution provides discreet, efficient, and safe pedaling assistance, maintaining the bicycle's lightweight nature, preventing damage from unexpected stops, and allowing customizable support, enhancing usability for various riders and terrain without adding noticeable weight or resistance.
Implementation Method 1
The motor is fitted with a planetary gearbox
Implementation Method 2
The crank shaft pinion gearhead is connected to a crank shaft through a bearing
Implementation Method 3
a pinion with dynamometric system to prevent the axis from breaking
Data Source
Figure 1
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AI summary
The invention is a single motor power unit, suitably for being mounted onto a bicycle frame, which is fitted with a motor (7), related power supply (13), bearings (8), crank shaft pinion gearhead (11), propulsor pinion gearhead (10), planetary gearbox (15) and central processor unit (12). It is characterized in that the propulsor pinion gearhead (10) is connected to a pinion with dynamometric system (19), having an at least approximately identical axis, and to a planetary gearbox (15) therethrough, while the inside of the bearing (8) is in fixed connection with the crank shaft (9) and the outside of the bearing (8) is in fixed connection with the crank shaft pinion gearhead (11). The invention is also the procedure for placing the power unit according to claim suitably into a bicycle frame.