Modular Three-Speed EV Transmission With Dual Planetary Gearsets
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Solution Overview
Problem
Existing transmission designs for electric and hybrid drive systems are not optimized for the distinct speed and torque curves of electric motors, leading to inefficiencies and the need for more complex, less reliable components.
Innovation Solution
A modular transmission system utilizing a combination of planetary gearsets, brakes, and clutches to provide multiple gear ratios and reverse capabilities, allowing for simplified operation and reduced wear parts, with the option for hybrid electric and internal combustion engine configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional transmission designs optimized for internal combustion engines are used, then engine speed and torque curves are well-matched, but electric motor speed and torque curves are not efficiently accommodated
Solution Approach 1:
The transmission is divided into two separate planetary gearsets (first and second planetary gearsets) with distinct functions. The first planetary gearset provides a first gear ratio while the second planetary gearset provides a second gear ratio, allowing each gearset to be independently optimized for electric motor characteristics rather than requiring a single complex geartrain optimized for combustion engines
Solution Approach 2:
The transmission uses controllable coupling mechanisms (clutches and brakes) to dynamically engage or disengage different gear pathways based on operating conditions. This allows the transmission to adaptively select between different gear ratios and operational modes to match the variable speed and torque characteristics of electric motors
2Productivity
If multiple planetary gearsets are used to achieve efficient gear ratios, then gear ratio efficiency improves, but the number of components and manufacturing complexity increases
Solution Approach 1:
The output shaft of the first planetary gearset is directly coupled to the input shaft of the second planetary gearset, merging the two gearsets into a compact integrated unit. This direct coupling eliminates the need for intermediate shafts, bearings, and housings that would otherwise be required, simplifying manufacturing while maintaining the efficiency benefits of multiple gear ratios
Solution Approach 2:
The shared shaft between the two planetary gearsets serves multiple functions: it acts as the output shaft for the first gearset, the input shaft for the second gearset, and provides a common mounting structure for both gearsets. This multi-functionality reduces the total number of components required and simplifies the overall manufacturing process
3Reliability
If traditional transmission components are used, then engine power is effectively transmitted, but wear parts increase and reliability decreases for electric drive systems
Solution Approach 1:
The transmission replaces traditional mechanical friction-based clutches and brakes with electromagnetic or electro-hydraulic actuation systems. This substitution eliminates the sliding friction and wear associated with traditional mechanical engagement mechanisms, significantly improving reliability for electric drive applications while reducing the number of wear-prone parts
Data Source
AI summary
A drive system for a vehicle that includes a transmission with three forward and three reverse gears. The transmission is optionally coupled to an electric motor as part of a fully electric or hybrid drive system. The transmission optionally includes a first and a second planetary gearset, a first and a second brake, and a clutch which may be separated into individual drive modules, optionally in separate detachable housings. A single electric motor may be provided with a single transmission, or multiple electric motors may be included to individually drive multiple separate tires, tracks, or other earth engaging elements. Single or multiple motors may be arranged upstream or downstream of the transmission, and they may be aligned parallel with or perpendicular to a drive axle.