Three-Speed EV Gearbox Using Planetary Sets and Selectable Clutches
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electric vehicles with single-speed gearboxes face limitations in providing sustained high torque and varying speeds, leading to suboptimal range and performance for on-road usage, and often feature complex gearing arrangements with packaging constraints.
Innovation Solution
A three-speed gearbox assembly for electric drive vehicles, incorporating four planetary gear sets and selectively engageable clutches, including a one-way clutch, to provide multiple gear ratios and differential functions without the need for complex controls or dedicated differential assemblies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If higher ratio gearing is used to provide sustained high torque, then torque capability is improved, but vehicle range and performance are worsened
Solution Approach 1:
The patent applies dynamics by implementing a multi-speed gearbox that allows the vehicle to dynamically change gear ratios based on driving conditions. The system transitions from a fixed single-speed configuration to a dynamic multi-speed system with selectable gear ratios, enabling optimal torque multiplication at low speeds and efficient direct drive at high speeds, thus resolving the contradiction between torque capability and range/performance adaptability
Solution Approach 2:
The patent changes the gear ratio parameter from a fixed single value to multiple selectable values. By providing a first gear ratio for high torque, a second gear ratio for sustained high torque, and a third gear ratio for high-speed operation, the system can adjust the transmission ratio parameter to match different operating requirements, resolving the contradiction between torque capability and overall vehicle performance
2Adaptability or versatility
If complex gearing arrangements are used to achieve multiple speeds, then speed variability is improved, but device complexity and packaging constraints are worsened
Solution Approach 1:
The patent merges multiple planetary gear sets into a single integrated transmission unit. By combining a first planetary gear set, a second planetary gear set, and a third planetary gear set into one compact multi-speed gearbox assembly, the system achieves multiple gear ratios without requiring separate gearboxes or complex external linkages, thus reducing overall device complexity while maintaining speed variability
Solution Approach 2:
The planetary gear sets serve multiple functions simultaneously: they provide gear ratio multiplication, enable differential motion between wheels, and allow for compact packaging. The same planetary gear mechanism that provides gear reduction also serves as the differential mechanism, eliminating the need for separate differential assemblies and reducing overall system complexity
Data Source
AI summary
A three-speed gearbox assembly for an electric drive vehicle includes four planetary gear sets connected to an electric motor output. A first clutch is configured to selectively couple the motor output to the first planetary gear set. A second clutch is configured to selectively ground a first portion of the first planetary gear set and a portion of the second planetary gear set to a housing. A selectable one-way clutch (SOWC) is configured to selectively ground a second portion of the first planetary gear set. The gearbox assembly is selectively switchable between (i) a first gear where the SOWC is engaged and the first and second clutches are disengaged, (ii) a second gear where the second clutch is engaged and the first clutch and the SOWC are disengaged, and (iii) a third gear where the first clutch is engaged and the second clutch and the SOWC are disengaged.