Bicycle Tire-Tooth Assist Drive for Lightweight Wheel Removal
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Solution Overview
Problem
Existing electrical assistance devices for bicycles face challenges such as increased mass sensitivity, complex wheel dismantling due to electrical connections, and architectural impacts on bicycle frames, as well as issues with stone retention and friction-driven wheel mechanisms.
Innovation Solution
A bicycle with an electrical assistance device featuring a motor pinion that meshes tangentially with rubber teeth on the tire, where the fixing means are carried by the frame, allowing for easy assembly and disassembly, and a separable subassembly including the electric machine, control, and battery, which can be folded and stored compactly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a hub motor is used to drive the wheel, then the wheel can be driven directly, but the mass is significant and located at the wheel making it very sensitive for the cyclist
Solution Approach 1:
The motor is extracted from the wheel hub and relocated to the bicycle frame. The motor unit is mounted on the frame with arms that connect to the wheel axle, separating the heavy motor mass from the wheel while maintaining direct wheel drive capability through the arm mechanism.
2Power
If a hub motor is used, then the wheel can be driven, but the wheel dismantling process is complicated by electrical connections and specific hub fasteners
Solution Approach 1:
The motor is extracted from the wheel hub, eliminating electrical connections and specialized fasteners from the wheel assembly. The wheel can now be removed and serviced using standard bicycle tools and procedures, while the motor remains mounted on the frame.
Solution Approach 2:
The drive system is segmented into separate components: the motor unit mounted on the frame, the transmission arms connecting to the axle, and the wheel itself. This modular segmentation allows the wheel to be independently removed and serviced without affecting the motor or electrical systems.
3Adaptability or versatility
If a geared motor unit driving the crankset is used, then the existing drivetrain can be utilized, but the bicycle architecture is significantly altered requiring specific frame designs
Solution Approach 1:
The motor unit is designed with universal mounting arms that can accommodate different wheel axle configurations. The arms connect to the existing wheel axle without requiring specialized frame designs, allowing the system to work with standard bicycle frames while providing electric assist.
4Power
If rim teeth are used for motor pinion meshing, then the wheel can be driven, but the rim teeth are susceptible to trapping pebbles
Solution Approach 1:
The tooth meshing interface is moved from the rim surface to the tire sidewall area. The motor pinion teeth mesh with corresponding teeth on the tire rather than the rim, changing the spatial dimension of the drive interface to a location less susceptible to pebble accumulation and more easily accessible for maintenance.
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 solution provides a lightweight, easy-to-maintain, and architecturally non-intrusive electrical assistance system that reduces weight and complexity during maintenance, while ensuring efficient power transmission and minimizing noise and stone retention.
Implementation Method 1
a motor pinion (3) driven by the rotor (2) of the electric machine (2), wherein the motor pinion (3) has teeth which mesh tangentially with complementary teeth (51) mainly made of rubber and attached to the tire (5) of the bicycle wheel
Implementation Method 2
the motor pinion (3) has teeth which mesh tangentially with complementary teeth (51) mainly made of rubber attached to the tire (5)
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates, in particular, to an electric power-assist device for bicycles, said device comprising: an electric machine (2) comprising a rotor; means (4) for securing the electric machine; a battery (7) for powering the electric machine; means for controlling the electric machine; a driving pinion (3) driven by the rotor of the electric machine; and a frame (10), said device being characterised in that the driving pinion can mesh tangentially with complementary teeth (51) solidly connected to a tyre (5) of a rear wheel (61) of the bicycle, and in that the securing means are borne by the frame, said frame comprising arms (101, 102, 103, 104) that can be secured to the axle of the rear wheel of the bicycle.