Electric Cycle Propulsion Unit Thermal Management
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Solution Overview
Problem
Existing pedal-assisted cycle propulsion units are bulky, heavy, and aesthetically unattractive due to the need for large motor units, heavy battery packs, and inefficient thermal management, which compromises compactness, lightness, and cost-effectiveness while increasing the risk of malfunction from excessive heating.
Innovation Solution
A compact rear propulsion unit design with an electric machine where the rotor is coaxial and external to the stator, with the electronic unit positioned inside the housing and supported by an intermediate thermally conductive element for efficient heat dissipation, and a decentralized transmission system that optimizes torque delivery and cooling by leveraging air flow during motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the propulsion unit includes various components including the motor unit provided with stator and rotor, the battery pack and the means of transmission of the movement of the motor unit to the crank axis, then the drive torque and motor autonomy are improved, but the weight and bulkiness increase
Solution Approach 1:
The electronic unit is integrated inside the propulsion unit housing rather than being placed externally, merging multiple components into a single compact assembly. This reduces the overall bulkiness while maintaining all necessary functions for drive torque generation.
Solution Approach 2:
The electronic unit is nested within the containment space of the propulsion unit, with the rotor being coaxial and external to the stator. This nested arrangement optimizes space utilization and reduces the overall footprint and weight of the propulsion unit while maintaining full functionality.
2Power
If the propulsion unit includes various components including the motor unit provided with stator and rotor, the battery pack and the means of transmission of the movement of the motor unit to the crank axis, then the drive torque and motor autonomy are improved, but the compactness and lightness deteriorate
Solution Approach 1:
The electronic unit is integrated inside the propulsion unit housing rather than being placed externally, merging multiple components into a single compact assembly. This reduces the overall bulkiness while maintaining all necessary functions for drive torque generation.
Solution Approach 2:
The electronic unit is nested within the containment space of the propulsion unit, with the rotor being coaxial and external to the stator. This nested arrangement optimizes space utilization and reduces the overall footprint and weight of the propulsion unit while maintaining full functionality.
3Volume of moving object
If the components of the propulsion unit are tightly packed to limit the overall dimensions, then the compactness is improved, but the thermal stress on the motor increases
Solution Approach 1:
An intermediate thermally conductive element is introduced between the electronic unit and the containment space wall. This intermediary component facilitates efficient heat transfer from the electronic unit to the external environment, allowing compact packaging while managing thermal stress through the thermal conduit function of the intermediate element.
4Temperature
If the electronic unit is placed outside the propulsion unit for easy cooling, then the thermal management is improved, but the aesthetic appearance deteriorates and the overall dimensions increase
Solution Approach 1:
The electronic unit is integrated inside the propulsion unit housing rather than being placed externally, merging multiple components into a single compact assembly. This reduces the overall bulkiness while maintaining all necessary functions for drive torque generation.
Solution Approach 2:
An intermediate thermally conductive element is introduced between the electronic unit and the containment space wall. This intermediary component facilitates efficient heat transfer from the electronic unit to the external environment, allowing compact packaging while managing thermal stress through the thermal conduit function of the intermediate element.
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 achieves a compact, lightweight, and aesthetically pleasing propulsion unit with improved thermal management, enhanced stability, and efficient power assistance, while maintaining drive torque and autonomy, thus overcoming the limitations of prior art.
Implementation Method 1
The electronic unit is positioned inside said housing and supported by an intermediate thermally conductive element so as to improve the dissipation of the heat generated by the electronic unit
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Propulsion unit (8) for an electric pedal assisted cycle (EPAC) comprising an electric machine (12) having a stator (14) and a rotor (16), rotatable about a motor axis (M-M), said rotor (16) being operatively connected to a crank pin (18), defining a crank axis (X-X), mechanically connected to the pedals (20), wherein the propulsion unit (8) comprises at least an electronic unit (32) for operating and controlling the functioning of the electric machine (12), wherein the propulsion unit (8) comprises at least a pair of housings (24,26) defining a containment space (28) which houses the electric machine (12) and at least partially the crank pin (18), wherein the propulsion unit (8) comprises transmission means (36) of the motion from the rotor (16) to the crank pin (18), wherein the electronic unit (32) is contained and supported inside said containment space (28) by an intermediate support element (40), said intermediate support element (40) being in contact with at least one of said housings (24,26) so as to dissipate the heat through these to the outside of the propulsion unit (8).