Hybrid WHR Drive Decoupling for Variable-Speed Energy Recovery
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Solution Overview
Problem
Current waste heat recovery (WHR) systems in hybrid vehicles are limited in efficiency due to their series connection with motor/generators, restricting the speed of the WHR system to match the motor/generator speed, which can hinder optimal operation and energy conversion.
Innovation Solution
A WHR hybrid power drive system that includes a WHR power unit, a motor/generator, and a mechanical linkage, allowing independent operation and decoupling of the WHR drive shaft from the motor/generator drive shaft, enabling variable speed rotation and simultaneous power transfer between the WHR drive shaft, motor/generator drive shaft, and output shaft, optimized for maximum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the WHR system is series connected with the motor/generator to match speeds, then the system structure is simplified, but the WHR system cannot operate at optimal speed and energy conversion is hindered
Solution Approach 1:
The patent segments the powertrain into independent WHR drive shaft and motor/generator drive shaft, allowing each to operate independently at optimal speeds. The WHR system is separated from the motor/generator series connection, enabling the WHR expanders to rotate at speeds optimized for waste heat conversion while the motor/generator operates at its own optimal speed range.
Solution Approach 2:
The patent implements dynamic speed control through a multi-speed transmission system with selectable gear ratios. The WHR drive shaft can be coupled to the motor/generator drive shaft through different transmission ratios, allowing the WHR system to operate at variable speeds that optimize energy conversion from waste heat while adapting to different vehicle operating conditions.
2Device complexity
If the WHR drive shaft is coupled to the motor/generator drive shaft through fixed ratio transmission, then power transfer is simplified, but the WHR system cannot adapt to varying operating conditions for maximum efficiency
Solution Approach 1:
The patent employs a multi-speed transmission system with selectable gear ratios that can be dynamically changed based on operating conditions. The transmission includes multiple planetary gear sets that can be engaged or disengaged to provide different speed ratios, allowing the WHR system to adapt to varying vehicle speeds, loads, and thermal conditions for maximum energy recovery efficiency.
Solution Approach 2:
The patent changes the transmission ratio parameter dynamically by engaging different gear sets in the multi-speed transmission. This allows the speed relationship between the WHR drive shaft and motor/generator drive shaft to be adjusted according to operating conditions, optimizing the WHR system performance across different vehicle operating ranges.
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
This configuration enhances the WHR system's efficiency by allowing independent operation and variable speed control, optimizing the performance of both the WHR power unit and the motor/generator, thereby improving energy conversion and utilization of waste heat.
Implementation Method 1
The WHR power unit is structured to convert thermal energy into rotation of a WHR drive shaft
Data Source
AI summary
A vehicle system includes an engine, a transmission, a differential, and a waste heat recovery (WHR) drive that converts thermal energy into mechanical and electrical energy. The WHR drive can include a WHR power unit structured to convert thermal energy into rotation of a WHR drive shaft. A motor/generator having a motor/generator shaft can selectively operate as a motor or a generator. A mechanical linkage is structured to selectively link an output shaft to one of the WHR drive shaft and the motor/generator drive shaft independently of the other of the WHR drive shaft and the motor/generator drive shaft. The output shaft is selectively coupled to one of the engine, the transmission, or the differential. The vehicle system may also include a traction motor to provide drive to the vehicle. The output shaft can be selectively coupled to the traction motor or the engine.