Electric Propulsion Unit With Coaxial Differential and Flexible Coupling
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Solution Overview
Problem
Existing electric propulsion units for saddle-type vehicles are bulky and costly due to complex gear transmissions, leading to increased weight, power losses, and fuel consumption.
Innovation Solution
A compact propulsion unit design with a coaxial differential and flexible coupling between the drive shaft and bevel gear drive, reducing mechanical components and tolerances, and utilizing a single electric motor to drive both rear wheels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a complex gear transmission is used to transmit power from the electric motor to the differential, then the power transmission is achieved, but the weight, bulk, cost, and power losses increase
Solution Approach 1:
The patent removes the complex gear transmission system from between the electric motor and differential. The electric motor is directly coupled to the differential, extracting the unnecessary intermediate transmission components while maintaining power transmission functionality.
Solution Approach 2:
The electric motor and differential are merged into a single integrated unit, eliminating the need for separate transmission components. This direct coupling combines the motor and differential functions into one compact assembly, reducing overall weight and complexity.
2Power
If a complex gear transmission is used to transmit power from the electric motor to the differential, then the power transmission is achieved, but the bulk and cost increase
Solution Approach 1:
The complex gear transmission components are extracted and removed from the propulsion unit. Only the essential differential mechanism remains, significantly reducing the volume occupied by transmission components.
Solution Approach 2:
The motor and differential are combined into a compact integrated unit, minimizing the overall volume of the propulsion system while maintaining full power transmission capability.
3Power
If a complex gear transmission is used to transmit power from the electric motor to the differential, then the power transmission is achieved, but the power losses increase
Solution Approach 1:
The intermediate gear transmission components that cause power losses are extracted and removed. The direct coupling between motor and differential eliminates multiple gear meshing points, reducing mechanical energy loss.
4Power
If precise tolerances are required for the coupling between motor and transmission, then the power transmission efficiency is improved, but the manufacturing difficulty and cost increase
Solution Approach 1:
A flexible coupling element is introduced between the motor and differential. This flexible connection compensates for tolerance variations, allowing assembly without extremely precise tolerances while maintaining effective power transmission.
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 achieves a more efficient, lightweight, and cost-effective propulsion system with reduced mechanical losses and simplified assembly, enhancing the overall performance and reducing production costs.
Implementation Method 1
The flexible coupling protects the bevel gear drive against peaks. Moreover, thanks to the flexible coupling there is no need for very precise tolerances for the coupling between motor and transmission. Small errors in parallelism and orthogonality are balanced by the deformable elements, typically made of rubber
Data Source
Figure 1
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Figure 3~4
AI summary
A saddle-type riding vehicle is described having an electric propulsion unit (9). The propulsion unit comprises a casing (23) and, inside the casing (23), a differential (33) connected to a left transmission axle-shaft (39a) and to a right transmission axle-shaft (39b), coaxial with each other and both rotating around a rotation axis (B-B); An electric motor (31) is provided, integral with the casing (23) and having a drive shaft (47) with a rotation axis (A-A) 90°-oriented with respect to the left axle-shaft (39a) and to the right axle-shaft (39b).