Electric Motor Bicycle Rim Drive Cog Torque Transmission
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Solution Overview
Problem
Electric motor assisted bicycles face limitations in generating sufficient torque for steep inclines and rugged terrain, are often complex and prone to premature wear, and suffer from inefficiencies that reduce their range and capabilities.
Innovation Solution
The design features a bicycle with a drive cog coupled to a plurality of bearings around the wheel rim, driven by an electric motor, allowing for efficient torque transmission and seamless transition between human-powered and motor-assisted modes, using a clutch to enable freewheeling and regenerative recharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the electric motor is coupled directly to the wheel hub or chain ring, then the system structure is compact, but the torque generation capability is insufficient for steep inclines and rugged terrain
Solution Approach 1:
The patent moves the drive mechanism from the traditional hub or chain ring location to the rim perimeter of the wheel. By positioning multiple drive cogs around the rim perimeter rather than at the rotational axis, the system achieves greater torque multiplication through the increased radius, while maintaining a relatively simple overall structure.
Solution Approach 2:
The drive system is segmented into multiple independent drive cogs positioned around the rim perimeter, each engaging with corresponding bearings. This segmentation allows the torque to be distributed across multiple contact points, increasing overall torque capacity and providing redundancy if one engagement point fails.
2Ease of operation
If the drive cog is permanently engaged with the bearings, then the motor can continuously drive the wheel, but the bicycle cannot be pedaled in conventional manner without disengagement
Solution Approach 1:
The system transitions from a static engaged state to a dynamic state where the drive cog can be selectively engaged or disengaged from the bearings. This allows the bicycle to switch between motor-assisted mode (engaged) and conventional pedaling mode (disengaged), providing operational flexibility without compromising drive reliability when engaged.
3Reliability
If the system uses traditional hub or chain ring drive, then the structure is simpler, but the system is prone to premature wear, damage or malfunction
Solution Approach 1:
The patent extracts the drive engagement from the traditional hub or chain ring location and relocates it to the rim perimeter. This separation removes the drive mechanism from areas subject to high stress and contamination, reducing wear and damage while maintaining a relatively simple overall system architecture.
4Use of energy by moving object
If the electric motor is positioned at the wheel center, then the weight distribution is balanced, but the torque transmission efficiency is reduced
Solution Approach 1:
The drive mechanism is relocated from the central rotational axis to the rim perimeter, utilizing the increased radius to maximize torque transmission efficiency. The motor remains positioned at the wheel center for balanced weight distribution, while the drive cogs extend outward to engage the rim, effectively separating the motor positioning function from the torque application point.
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 enhances torque delivery, reduces power consumption, and extends the range and performance of electric motor assisted bicycles, making them more effective for hill climbing and off-road use while maintaining conventional pedaling capabilities.
Implementation Method 1
the electric motor is coupled to the drive cog via a clutch, such as, for example, a needle bearing clutch or an electromagnetic clutch, to selectively transmit power from the electric motor to the drive cog
Implementation Method 2
a plurality of bearings uniformly spaced around a perimeter of a rim of one of the front and rear wheels, each of the plurality of bearings including a cylindrical engagement profile
Data Source
AI summary
An electric motor assisted bicycle is provided having a fork, a frame, a front wheel, a rear wheel, and pedals drivingly coupled to at least one of the front and rear wheels to enable human powered motion of the bicycle. The bicycle further includes a plurality of bearings uniformly spaced around a perimeter of a rim of one of the front and rear wheels and an electric motor drive system coupled to the bicycle to selectively provide electric motor assisted motion thereof. The electric motor drive system includes an electric motor coupled to the bicycle and a drive cog drivingly coupled to the electric motor, the drive cog positioned to sequentially engage the plurality bearings when driven by the electric motor to power the bicycle in a motor assisted manner. Other bicycle systems and components and related methods are also provided.