Multi-mode Electromechanical Transmission for Electric Vehicles
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Solution Overview
Problem
Traditional vehicle transmissions rely on mechanical gear systems, which limit flexibility and efficiency in speed and torque conversions, especially in electric vehicles that require innovative solutions for propulsion and accessory power without mechanical engine input.
Innovation Solution
A multi-mode electromechanical variable transmission system incorporating planetary devices, electromagnetic machines, and an energy storage system, allowing for selective reconfiguration between various operating modes using clutches and brakes, enabling electric-only operation and efficient power distribution between wheels and accessories.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional mechanical gear systems are used for speed and torque conversions, then the transmission structure is simple and reliable, but the flexibility and efficiency in speed and torque conversions are limited
Solution Approach 1:
The transmission system is divided into multiple independent planetary gear sets (first planetary gear set, second planetary gear set) that can be selectively engaged or disengaged. Each gear set can operate independently or in combination, allowing flexible speed and torque conversions without requiring a completely complex integrated mechanism. This segmentation enables the system to achieve multiple transmission ratios while maintaining manageable complexity.
Solution Approach 2:
The transmission system employs dynamic engagement and disengagement of planetary gear sets through clutches and brakes, allowing the system to adapt its configuration in real-time based on operating conditions. The selective coupling of gear sets enables dynamic adjustment of speed and torque characteristics, providing versatility while maintaining a relatively simple base structure that only becomes complex when actively reconfigured.
2Adaptability or versatility
If mechanical engine input is used to drive the transmission, then the propulsion system is simple, but electric vehicles cannot efficiently operate without mechanical engine input
Solution Approach 1:
The transmission system is designed to accept power input from multiple sources - either mechanical engine input or electrical motors. The planetary gear sets and connecting shafts can be driven by electrical motors in electric vehicle mode, or by mechanical engine input in hybrid mode. This multi-functionality allows the same transmission structure to serve both propulsion and accessory power needs without requiring separate systems, thereby achieving versatility without proportionally increasing complexity.
Solution Approach 2:
The system replaces the traditional purely mechanical engine-driven transmission with an electromechanical system where electrical motors can directly drive the planetary gear sets. This substitution eliminates the need for a mechanical engine while maintaining the transmission's core functions. The electrical motors provide precise control over speed and torque, enhancing efficiency in electric vehicle operation without requiring a completely new transmission architecture.
3Productivity
If planetary gear sets are selectively coupled to provide multiple gear ratios, then speed and torque conversion efficiency is improved, but the transmission mechanism becomes more complex
Solution Approach 1:
Multiple planetary gear sets are merged into a single integrated transmission system with shared components such as the connecting shaft and common housing. The first and second planetary gear sets are coupled through the connecting shaft, allowing them to work together as a unified system. This merging reduces the overall complexity compared to having separate independent gear systems, while still providing multiple gear ratios through selective engagement of the combined gear sets.
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 system provides flexible and efficient speed and torque management, enabling electric vehicles to operate without mechanical engine input, enhancing propulsion and accessory power delivery across different modes, improving energy efficiency and operational versatility.
Implementation Method 1
a first electromagnetic device and a second electromagnetic device configured to receive electrical energy from an energy storage device and provide rotational mechanical energy to the transmission
Data Source
AI summary
A drive system for a vehicle includes first and second electrical machines, a transmission, and an electrical energy supply. The transmission includes first and second gear sets, a connecting shaft coupled to the first gear set, a driveshaft configured to transport power from the electrical machines to a tractive element of the vehicle, and a clutch. The first gear set is coupled to the first electrical machine. The second gear set is coupled to the second electrical machine. Carriers of the first and second gear sets are coupled. The clutch selectively rotationally couples the carriers to the driveshaft when engaged. The drive system operates in an electric only configuration whereby the electrical energy supply provides electrical energy to at least one of the electrical machines to drive at least one of the connecting shaft and the driveshaft without a mechanical energy input to the transmission from an engine.