Dual e-Axle Gear Ratio Layout for Torque-Speed Flexibility
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Solution Overview
Problem
Conventional electric vehicles with single-speed e-axles lack flexibility in gear ratios, leading to inefficient performance across different operating conditions, and do not have a neutral position, which is beneficial for towing and failure mitigation.
Innovation Solution
A dual electric axle system with one multi-ratio e-axle and one single-speed e-axle, allowing independent gear ratio control for each axle, enabling neutral position operation, and reconfiguration for optimal torque/speed combinations without increasing mass or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single predetermined gear ratio is used for all axles, then the device complexity is reduced and manufacturing cost is lowered, but the adaptability to different operating conditions deteriorates
Solution Approach 1:
The patent divides the axle system into multiple independent e-axles, each capable of having different gear ratios. Instead of using a complex multi-ratio mechanism in every axle, the system segments the gear ratio variation across different axles, allowing each axle to be simpler while the overall system achieves adaptability through differentiation between axles.
Solution Approach 2:
The patent applies different gear ratios to different axles based on their specific operational requirements. Each axle can be optimized with a gear ratio suited to its local function and operating conditions, rather than using a uniform gear ratio throughout the entire vehicle system.
2Force
If a higher axle ratio is selected for quick starts with high torque, then the force for initiating motion is improved, but the speed for high-speed operation deteriorates
Solution Approach 1:
The patent segments the torque-speed requirements by assigning different gear ratios to different axles. One axle can be optimized with a higher gear ratio for torque-intensive operations like vehicle initiation, while another axle uses a lower gear ratio for high-speed operation, eliminating the need to compromise between these conflicting requirements.
Solution Approach 2:
The system dynamically selects which axle to power or which gear ratio to use based on real-time operating conditions. The control system can switch between different axle configurations to optimize performance for either torque delivery or speed, making the overall system adaptable rather than static.
3Productivity
If a compromise axle ratio is selected for mid-range speeds, then the efficiency at moderate operating points is improved, but the performance at extreme operating points (low speed/high torque or high speed/low torque) deteriorates
Solution Approach 1:
The patent segments the operating range coverage by assigning different gear ratios to different axles. One axle handles low-speed/high-torque operations while another handles high-speed/low-torque operations, ensuring that extreme operating points are covered without sacrificing mid-range efficiency in either axle.
Solution Approach 2:
The multi-axle system with different gear ratios provides universal coverage across the entire operating spectrum. Each axle serves multiple functions depending on operating conditions, with the system as a whole capable of handling diverse operating points that would be impossible for a single fixed gear ratio to optimize.
4Adaptability or versatility
If multi-ratio e-axles are used for both front and rear drive, then the adaptability to different operating conditions is improved, but the device complexity and cost increase
Solution Approach 1:
The patent segments the multi-ratio capability across different axles rather than implementing it in every axle. By having different gear ratios in different axles, the system achieves multi-ratio functionality without requiring complex shifting mechanisms in each individual e-axle, thereby reducing overall device complexity while maintaining adaptability.
5Device complexity
If a single-speed e-axle without neutral capability is used, then the device complexity is reduced, but the ability to disengage motor and gears from wheels for towing or failure mitigation deteriorates
Solution Approach 1:
The e-axle system incorporates neutral capability as a universal feature across all axles, enabling them to be disengaged from the wheels when needed. This multi-functional capability allows the same axle structure to serve both driven and neutral functions, providing towing and failure mitigation capabilities without requiring fundamentally different axle designs.
Data Source
AI summary
The electric axle (e-axle) system having variable gear ratios is disclosed. The e-axle system can include a first axle assembly having one axle gear ratio and a second axle assembly having two or more axle gear ratios that are selectively and independently controlled. In addition, each of the first and second axle assemblies is independently controlled to be in a neutral position.