Portable Friction Drive Device for E-Bike Tire Contact
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric drive systems for bikes are heavy and impractical due to numerous moving parts, and they fail to provide dynamic friction for braking and recharging, as well as free rolling, with existing solutions often pushing the drive wheel away from the tire during recharging.
Innovation Solution
A portable electric friction drive system with a bike bracket that securely attaches the friction drive device using a rigid attachment mechanism, featuring an inclination control arrangement to adjust the tilt of the drive wheel, allowing it to maintain a neutral inclination angle for efficient recharging and reduce unnecessary motor usage, eliminating the need for additional movable parts and minimizing friction losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional hub engine or crankcase engine is used, then the bike can achieve electric drive function, but the system becomes heavy and complex with many moving parts
Solution Approach 1:
The patent extracts the motor from the traditional hub or crankcase positions and relocates it to a portable friction drive device that contacts the tire externally. This separation allows the main bike structure to remain simple while the electric drive function is provided by an independent, removable unit with fewer integrated moving parts.
Solution Approach 2:
The friction drive device serves multiple functions: it provides electric drive assistance when the motor activates the drive wheel, enables regenerative braking when the tire drives the drive wheel to recharge the battery, and allows free rolling when disengaged. This multi-functionality eliminates the need for separate systems for each operation mode.
2Ease of operation
If the drive wheel is pivotally coupled to the friction drive device, then the device can adjust position, but it pushes the drive wheel away from the tire during recharging
Solution Approach 1:
The patent implements dynamic adjustment of the drive wheel's inclination angle through an inclination control arrangement that can tilt the drive wheel relative to the tire. This dynamic positioning allows the system to optimize the contact angle for both drive mode and regenerative braking mode, ensuring the drive wheel remains properly engaged with the tire during recharging rather than being pushed away.
Solution Approach 2:
The system changes the inclination angle parameter of the drive wheel to optimize performance in different operating modes. By adjusting this geometric parameter, the drive wheel maintains proper contact with the tire during regenerative braking, maximizing energy recovery efficiency.
3Loss of energy
If the motor rotates continuously for regenerative braking, then energy can be recovered, but magnetic and electrical losses occur unnecessarily when drive assistance is not required
Solution Approach 1:
The friction drive device operates autonomously in regenerative braking mode, where the rotating tire directly drives the drive wheel and motor without requiring external control input. The system automatically engages energy recovery when the bike is braking, capturing kinetic energy that would otherwise be lost, while remaining passive during free rolling to minimize energy consumption.
Solution Approach 2:
The motor operates periodically rather than continuously - activating only when drive assistance is needed or when regenerative braking is occurring. During free rolling or coasting, the motor remains inactive, eliminating unnecessary magnetic and electrical losses while still enabling energy recovery during deceleration phases.
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 a lightweight, efficient, and secure attachment system that allows for dynamic friction control, enabling higher energy efficiency by using the motor only when needed for braking or recharging, and allowing the bike wheel to rotate freely, thereby increasing recharge efficiency and extending battery life.
Implementation Method 1
an electric motor connected to the drive wheel, wherein the electric motor is configured to drive the drive wheel
Implementation Method 2
a drive wheel arranged at a front part of the friction drive device, adapted to be contactable to a tire of the bike at a contact point
Implementation Method 3
The inclination control arrangement is configured to control the inclination of the imaginary line between the second drive device attachment point and the contact point of the drive wheel by adjusting the tilt of the friction drive device over the second drive device attachment point. The inclination control arrangement is arranged at the rear part of the friction drive device and is configured to tilt the friction drive device by moving the friction drive device in a direction substantially perpendicular to said imaginary line to cause a rotational movement over the second drive device attachment point.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention relates to an electric drive system for a bike comprising a portable electric friction drive device (1) and a bike bracket (13) configured to be mounted on a bike. A first drive device attachment point (3') is located at a rear part of the friction drive device. A second drive device attachment point (4') is located between the front part of the friction drive device and the rear part of the friction drive device so that the friction drive device is configured to rest against the second bracket attachment point (4). An inclination control arrangement (2) is configured to control the inclination of the imaginary line between the second drive device attachment point and a contact point (9') of the drive wheel (9) by adjusting the tilt of the friction drive device over the second drive device attachment point. Further, the invention relates to a portable electric friction drive device. Yet further, the invention relates to bike (60, 70) having at least one wheel, comprising the electric drive system, wherein the drive wheel is arranged to be contactable to the tire of said wheel at said contact point.