E-Bike Drive Power Distribution for Low-Noise Plastic Gears
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Solution Overview
Problem
Conventional electric drives for bicycles are expensive and noisy due to the need for metallic wheels to handle high torques, which limits production costs and increases noise development.
Innovation Solution
The transmission is equipped with at least two offset output gears that split the drive power, reducing torque at each engagement point, allowing for the use of less expensive plastic wheels and minimizing noise by distributing the load across multiple points of engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a bicycle has both a drivetrain and an electric drive, then the bicycle can operate in multiple modes (pedaling, electric drive, coasting), but the structure becomes complex and components are redundant
Solution Approach 1:
The patent combines the drivetrain and electric drive into an integrated power distribution system where the electric drive unit includes a motor, generator, and battery that work together with the bicycle's drivetrain. The generator is driven by the pedals and charges the battery, which then powers the motor to assist pedaling or enable coasting, eliminating the need for separate redundant systems.
Solution Approach 2:
The electric drive unit performs multiple functions: the generator converts mechanical energy from pedaling into electrical energy to charge the battery, while the motor converts electrical energy from the battery into mechanical energy to assist the drivetrain. This multi-functional design allows the system to operate in multiple modes without requiring separate dedicated components for each function.
2Duration of action of moving object
If energy is stored in a battery for later use, then power can be distributed when needed, but the battery adds weight to the bicycle
Solution Approach 1:
The system dynamically changes the state of energy storage and delivery by charging the battery during high-energy input periods (downhill coasting or intense pedaling) and discharging it during high-power demand periods (acceleration or climbing). This parameter-based energy management allows the battery to serve as a buffer that smooths power delivery without requiring excessive capacity, thereby limiting weight increase.
3Device complexity
If the bicycle uses only a drivetrain without electric drive, then the structure is simple, but the bicycle cannot coast downhill or generate electricity from pedaling
Solution Approach 1:
The generator is directly driven by the bicycle's drivetrain through the chain and sprockets, so that during downhill coasting or intense pedaling, the kinetic energy of the bicycle automatically drives the generator to produce electrical energy that charges the battery. The system serves itself by converting excess mechanical energy into stored electrical energy without requiring external intervention or complex control systems.
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 design reduces production costs and noise issues by allowing the use of plastic wheels while maintaining performance, and also increases ground clearance by positioning the drive components compactly above the pedal crankshaft.
Implementation Method 1
a generator to convert mechanical energy into electrical energy to be stored in the battery
Implementation Method 2
a motor to convert electrical energy into mechanical energy to drive the drivetrain
Data Source
Figure 1~2
Figure 3~4
AI summary
The present invention relates to an electric drive (2) for a bicycle (1), the electric drive - comprising an electric motor (5) which has an input shaft (8), - comprising an output shaft (6) which is connected to a driving gear (11) for conjoined rotation in order to couple same to a wheel drive (4) of the bicycle (1), - comprising a transmission (7) which drivingly connects the input shaft (8) to the output shaft (6), - wherein the transmission has an output gear (12), which is connected to the output shaft (6) for conjoined rotation in a rotational drive direction (13), and at least two drive gears, namely a first drive gear (14) and a second drive gear (15), which each mesh with the output gear (12) at a distance from each other in the circumferential direction (16) in order to drive the output gear (12), -wherein the transmission (7) has a power distribution (17) which divides a drive power of the electric motor (5) between the drive gears (14, 15).