External Rotor Motor for Driveshaft Torque
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Bicycles with driveshaft transmission systems and internal rotor electric auxiliary motors face inefficiencies in torque transfer and complex design, leading to clumsy and ineffective propulsion assistance.
Innovation Solution
Implementing an external rotor type electric motor with a planetary gear and one-way overrunning clutch between the driveshaft and wheel hub, allowing for higher torque delivery and a compact, maintenance-free design, while minimizing service needs and maintaining a sleek appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an internal rotor type electric auxiliary motor is arranged in the crank area, then the motor can assist the user while pedalling, but the motor appears clumsy and the design becomes complex
Solution Approach 1:
The motor is relocated from the traditional crank area to the rear wheel hub area, changing the spatial dimension of motor placement. This allows the motor to be integrated into the wheel hub structure rather than the crank, achieving a cleaner overall design while maintaining auxiliary propulsion functionality
Solution Approach 2:
The motor is nested within the rear wheel hub structure, with the stator positioned inside the hub and the rotor extending outward. This nesting approach allows the motor to be compactly integrated into the wheel assembly, reducing overall complexity and improving aesthetics
2Power
If an internal rotor type electric auxiliary motor is arranged at the driveshaft, then the motor can provide auxiliary power, but the motor has small diameter and cannot provide sufficient torque
Solution Approach 1:
The motor design transitions from internal rotor to external rotor configuration, where the rotor extends outward from the hub rather than being contained within. This dimensional change allows for a larger effective diameter and greater torque output while maintaining compact integration with the wheel hub
Solution Approach 2:
The motor parameters are optimized by changing from internal to external rotor configuration, increasing the effective radius and moment arm for torque generation. This parameter change enables the motor to deliver sufficient torque for effective auxiliary propulsion
3Speed
If a large gear transmission is arranged in the crank to increase shaft revolutions, then the shaft can run at higher rpm, but the crank becomes complex and clumsy
Solution Approach 1:
The complex gear transmission system is extracted from the crank area and relocated to the rear wheel hub. This extraction simplifies the crank design, allowing it to maintain a clean, traditional appearance while the necessary speed multiplication is achieved through the motor's direct integration with the hub and drivetrain
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 provides a bicycle with efficient torque assistance, reduced maintenance requirements, and a stylish design by leveraging the external rotor motor's higher torque and compact construction, ensuring effective power transfer and comfortable riding with minimal mechanical complexity.
Implementation Method 1
The invention further comprises a planetary gear and a one-way overrunning clutch, said one-way overrunning clutch and said planetary gear being arranged between the driveshaft and the rotor part
Implementation Method 2
The invention further comprises a planetary gear and a one-way overrunning clutch, said one-way overrunning clutch and said planetary gear being arranged between the driveshaft and the rotor part
Implementation Method 3
an electric motor for propelling said vehicle, said electric motor being arranged at said driveshaft
Data Source
AI summary
A vehicle with a driveshaft transmission system having a driveshaft and a hub at a wheel of the vehicle, a battery pack and an electric motor for propelling the vehicle arranged at the driveshaft as well as a driveshaft transmission system. The electric motor can be a motor of the external rotor type having an inner stator part and an outer rotor part, the inner stator part having a central passage for the driveshaft. The driveshaft transmission system has an auxiliary motor with a planetary gear and a one-way overrunning clutch, the one-way overrunning clutch and the planetary gear being arranged between the driveshaft and the rotor part.