Bicycle Tyre Sidewall Teeth for Electric Assist
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Solution Overview
Problem
Existing bicycle tires with integrated electrical assistance devices face issues with teeth retention of foreign objects and inadequate dimensioning for motor pinion engagement, leading to inefficiencies in torque transmission and noise generation.
Innovation Solution
A bicycle tire design featuring continuous, substantially radial generator teeth on the sidewall, made of elastomeric material with a specific shear modulus and triangular section geometry, optimized for engagement with motor pinion teeth, ensuring efficient torque transmission and reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If teeth are positioned on the rim for electrical assistance device, then motor pinion can engage with the teeth, but stones are likely to be retained on the teeth
Solution Approach 1:
The teeth are extracted from the rim and repositioned to the tire sidewall, separating the engagement function from the rim structure. This allows the rim to remain smooth and free of stone retention issues while the sidewall teeth provide the necessary motor pinion engagement.
2Power
If generator teeth are positioned on the tire sidewall, then torque transmission is enabled, but the teeth must be precisely dimensioned for motor pinion engagement
Solution Approach 1:
The tooth parameters (pitch, module, profile) are specifically changed and optimized to match the motor pinion dimensions. The patent defines precise geometric parameters including pitch p, tooth height h, and triangular section dimensions to ensure proper meshing and torque transmission while maintaining manufacturability.
3Reliability
If the elastomeric material has high shear elasticity modulus, then tooth displacement is reduced for better engagement, but the material becomes less flexible
Solution Approach 1:
The shear elasticity modulus G* is changed to specific ranges (0.5-5 MPa) to achieve the optimal balance. This parameter change ensures that tooth displacement d remains between 0.15-0.3 times the tooth height h, providing stable engagement while maintaining sufficient material flexibility for the elastomeric compound.
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 design maintains contact with complementary teeth under motor torque, reduces noise, and is tolerant of misalignment and foreign bodies, enhancing the efficiency and reliability of electrical assistance systems.
Implementation Method 1
each tooth comprising an elastomeric material having a modulus of shear elasticity G*, the shear elasticity modulus G* of the elastomeric material of the teeth being at least equal to a threshold shear elasticity modulus G* s, the threshold shear elasticity modulus G* s being such that the displacement d of the top of each tooth is equal to 0.2 times the height h of the tooth, under the action of a uniform pressure
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~4B
AI summary
Bicycle tyre and, more particularly, a bicycle tyre intended to collaborate with an electrical assistance device. The object of the invention is to propose a bicycle tyre (1) comprising a toothset (5) of substantially radial generatrix (G) positioned circumferentially on a side wall (2) of the tyre and intended to collaborate with a complementary toothset of a driving pinion of an electrical assistance device for a bicycle. According to the invention, as the toothset (5) is made up of teeth (51) which are equidistant by a pitch p, each tooth (51) having a length l in the direction of the generatrix (G) and a cross section that is substantially triangular, in a plane perpendicular to the generatrix (G), of height h, each tooth (51) comprising an elastomeric material having a shear elastic modulus G*, the shear elastic modulus G* of the elastomeric material of the teeth (51) is at least equal to a threshold shear elastic modulus G*s, the threshold shear elastic modulus G*s being such that the shifting d of the tip of each tooth (51) is equal to 0.2 times the height h of the tooth (51) under the action of a uniform pressure applied by the complementary toothset to the side forming the smallest angle of opening, equal to 650/(1 × h × (2.67-0.33 × p)).