Cone Ring Transmission in E-Bike Crank for Quiet Shifting

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Solution Overview

Problem

Existing electric bicycles with bottom bracket motor configurations face limitations in achieving a compact design and smooth gear shifting, particularly under load, with noise and mechanical jumps in transmission ratio changes.

Innovation Solution

A compact design incorporating a continuously variable cone ring transmission with a crank mechanism, where the cone ring gear is integrated within the crank mechanism, allowing stepless gear ratio adjustment and quiet operation, eliminating the need for a separate shifting device on the rear wheel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a derailleur gear or hub gear is arranged on the rear wheel, then gear shifting is enabled, but the vehicle structure becomes more complex and the center of gravity rises

Engineering Contradiction:

Improvegear shifting capabilityVSAvoidvehicle structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines the gear shifting function with the bottom bracket motor by integrating a cone ring transmission directly into the crank mechanism. The transmission ring is displaceably arranged between two cones within the bottom bracket assembly, merging the previously separate functions of motor housing and gear shifting mechanism into a single integrated unit. This eliminates the need for separate derailleur or hub gear systems on the rear wheel.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent moves the gear shifting function from the rear wheel dimension to the bottom bracket dimension. By placing the cone ring transmission at the bottom bracket, the system changes the spatial dimension where gear shifting occurs, allowing continuous variable ratio changes without requiring rear wheel components and thereby simplifying the overall vehicle structure.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If a derailleur gear or hub gear is arranged on the rear wheel, then gear shifting is enabled, but the center of gravity rises affecting handling

Engineering Contradiction:

Improvegear shifting capabilityVSAvoidcenter of gravity

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If conventional gear shifting is used, then gear ratio changes are possible, but noise and mechanical jumps occur during shifting

Engineering Contradiction:

Improvegear ratio change capabilityVSAvoidnoise and mechanical jumps

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent employs a continuously variable transmission system where the transmission ring can be smoothly displaced between the two cones to achieve continuous gear ratio changes. This dynamic system allows the gear ratio to be adjusted at any point during operation without fixed discrete steps, enabling seamless transitions that eliminate mechanical jumps and reduce noise compared to conventional fixed-ratio shifting mechanisms.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent replaces the conventional mechanical derailleur or hub gear system with a cone ring friction-based transmission system. Instead of using chain tensioning and derailleur levers, the system uses friction contact between the transmission ring and conical surfaces to transfer power, allowing smooth continuous ratio changes without the noise and jumps characteristic of traditional mechanical shifting systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Enables a compact and efficient electric bicycle design with seamless interaction between pedal and electric drive, allowing continuous torque and speed control, reducing noise and mechanical jumps during gear changes, and providing a low center of gravity for improved handling.

Implementation Method 1

a cone ring gear with a transmission ring that is displaceably arranged between two cones... One of the cones serves as the drive and the other as the output of the cone ring gear

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentEP2986492B1Vehicle operable by means of a motor and using muscle power

Publication Date: 2020.01.01 ROBERT BOSCH GMBH

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AI summary

The present invention relates to a vehicle operable by means of motor power and/or pedaling power, in particular an electric bicycle, comprising a crank assembly (2) having a bottom bracket shaft (20), a chainwheel (4) which outputs drive torque for the vehicle to a chain (5), an electric drive (3) and a cone ring transmission (10) for the continuously variable changing of a transmission ratio, wherein said cone ring transmission (10) and the electric drive (3) are provided on said crank assembly (2) and wherein the cone ring transmission (10) is connected to the crank assembly (2) and arranged in such a way that a torque produced by a rider is transmitted to said chainwheel (4).