Rotatable Cooling Device for E-Bike Drive Heat Dissipation

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Solution Overview

Problem

Integrated electric drive devices in bicycles face challenges with heat dissipation, leading to reduced power output to avoid overheating, especially in carbon fiber frames which are poor at dissipating heat, making them visually unappealing and inefficient.

Innovation Solution

A cooling device with a heat sink, preferably made of thermally conductive materials like aluminum, is integrated into the drive housing, allowing heat to be dissipated externally through a rotatably mounted design that positions the cooling surface for optimal airflow and contact with the environment, ensuring constant power output and easy maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If the electric drive device is integrated into the bicycle frame, then the visual appearance is improved and protection from dirt and moisture is enhanced, but heat dissipation deteriorates leading to reduced power output

Engineering Contradiction:
Improvevisual appearanceVSAvoidheat dissipation
Core Design Contradiction:
ShapeVSTemperature

Solution Approach 1:

The drive unit is segmented into separate functional components: the motor housing integrated into the frame, and a detachable cooling device with heat sink that can be mounted separately on the motor housing. This segmentation allows the cooling device to be optimally positioned for heat dissipation while maintaining the integrated aesthetic of the frame integration.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cooling device acts as an intermediary between the heat-generating motor components and the external environment. The heat sink with its extended surface area and fin structure serves as a thermal mediator, transferring heat from the motor housing to the surrounding air through convection and radiation, thereby solving the heat dissipation problem without compromising the integrated design.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the cooling device is rotatably mounted on the drive housing, then adaptability to different frame angles is improved, but device complexity increases

Engineering Contradiction:
Improveangular positioningVSAvoidmounting mechanism
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The cooling device is mounted rotatably on the motor housing, transforming it from a static component to a dynamic one that can be positioned at different angles. This dynamic mounting allows the cooling device to adapt to various frame geometries and installation angles, providing versatility in integration while keeping the mounting mechanism relatively simple through the use of a rotation joint.

Inventive Principle:
Principle #15Dynamics

3Productivity

If power output is increased, then productivity is improved, but heat generation increases leading to overheating

Engineering Contradiction:
Improvepower outputVSAvoidheat generation
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The cooling device with its extended heat sink surface area is pre-configured and positioned before the drive device operates at high power. This preliminary preparation ensures that the thermal management system is ready to handle the heat that will be generated during high-power operation, allowing the drive to maintain constant power output without overheating by having the cooling capability in place beforehand.

Inventive Principle:
Principle #10Preliminary action

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 enables longer operation of integrated electric drive devices without overheating, allowing for constant power output and aesthetic integration into bicycle frames, even those made of carbon fiber, by effectively dissipating heat through enhanced thermal conductivity and airflow.

Implementation Method 1

The cooling device has a heat sink. The heat sink preferably has at least one outwardly directed cooling surface which is in contact with the environment.

Methodology Applied
Scientific EffectHeat sink: Heat Sink

Implementation Method 2

heat is transferred from the heat sink to the environment outside of the electric drive device. The heat is given off as warm air.

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

When the bicycle is started up, that is to say when the bicycle is actuated, the heat sink is cooled down as a result of the relative wind. In this case, cold air flows around the heat sink as a result of the air currents or air turbulence that occur.

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP3349337B1Dissipation of heat from a drive by an air stream for electric bicycles
Publication Date: 2020.02.12 ROBERT BOSCH GMBH
  • EP3349337B1 patent drawingFigure 1~2

AI summary

The present invention relates to a bicycle with an integrated electric drive device (1) comprising a drive housing (2) with heat sources (3, 8) and a cooling device (5) rotatably arranged relative to the drive housing (2) with a heat sink (6) for dissipating heat generated by the heat sources (3, 8) to the outside of the electric drive device (1).