Front-End Motor-Generator System for Hybrid Vehicles
Solution Overview
Problem
Existing hybrid electric vehicle systems face challenges in scaling up to handle high-torque outputs of large engines, particularly commercial vehicle diesel engines, due to engineering difficulties and inefficiencies in energy management, leading to increased weight, cost, and complexity, as well as limitations in independently meeting accessory power demands without auxiliary power units.
Innovation Solution
A hybrid electric vehicle system with a front-end motor-generator arrangement that includes a switchable coupling and torque transfer segment, allowing for flexible torque exchange between the engine crankshaft and motor-generator, enabling independent operation of engine accessories and supplemental propulsion, while minimizing space and weight requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a starter-generator is mounted at the front end of a large internal combustion engine, then the electric motor must be larger to handle higher torque demands, but this increases weight, size, and cost prohibitively
Solution Approach 1:
A belt drive system serves as an intermediary between the engine crankshaft and the electric motor. The belt drive transmits torque from the engine to the motor, allowing the motor to be sized for electrical power needs rather than mechanical torque needs. This decouples the torque transmission function from the motor itself, enabling the use of a smaller, lighter motor that can still handle the high torque demands of large engines.
Solution Approach 2:
The patent replaces direct mechanical coupling with a belt drive system, substituting a flexible mechanical transmission for rigid direct connection. This allows the electric motor to be decoupled from the high-torque mechanical environment of the engine, enabling the motor to be sized appropriately for its electrical function rather than being oversized to handle peak mechanical torque loads.
2Force
If the belt drive is enlarged to handle high torque demands, then torque capacity is sufficient, but the belt and pulleys become so much larger and heavier that they are weight, size and cost prohibitive
Solution Approach 1:
The belt drive system uses dynamic tensioning and pulley design to maximize torque transmission efficiency. By optimizing the belt tension, pulley diameter ratio, and wrap angle, the system achieves high torque capacity without requiring excessively large components. The dynamic design allows the belt drive to handle peak torque demands while maintaining reasonable component sizes and weights.
Solution Approach 2:
The patent optimizes multiple parameters of the belt drive system including belt material properties, pulley diameter ratios, belt tension forces, and wrap angles to achieve maximum torque transmission efficiency. By carefully selecting and adjusting these parameters, the system achieves the required torque capacity with minimized component sizes and weights, avoiding the need for oversized belts and pulleys.
3Adaptability or versatility
If multiple individual electric motors are used to drive engine accessories, then accessory power demands are met independently, but vehicle weight, cost, and system complexity increase significantly
Solution Approach 1:
A single electric motor mounted at the front end of the engine is designed to perform multiple functions: driving engine accessories (alternator, water pump, air conditioning compressor), providing regenerative braking, and assisting with engine starting. This multi-functional motor replaces what would otherwise require multiple separate motors, significantly reducing system complexity, weight, and cost while maintaining the ability to independently control accessory power demands.
Solution Approach 2:
The patent combines multiple previously separate functions (accessory drive, regenerative braking, engine starting assistance) into a single integrated electric motor system. By merging these functions into one motor with a common drive system and control architecture, the patent achieves independent accessory control without the complexity and cost of multiple separate motor systems.
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 enhances fuel efficiency, reduces emissions, and eliminates the need for heavy auxiliary power units by efficiently managing energy and torque distribution, allowing for independent operation of accessories and supplemental propulsion, thus improving overall vehicle performance and reducing costs.
Implementation Method 1
a motor-generator and an electrical energy storage system have been the focus of considerable attention in the automotive field
Implementation Method 2
hybrid electric systems' ability to recapture energy which would otherwise be wasted (such as mechanical energy from braking that would otherwise be dissipated as thermal energy to the environment)
Data Source
AI summary
A system and method are provided for hybrid electric internal combustion engine applications in which a motor-generator, a narrow switchable coupling and a torque transfer unit therebetween are arranged and positioned in the constrained environment at the front of an engine in applications such as commercial vehicles, off-road vehicles and stationary engine installations. The motor-generator is preferably positioned laterally offset from the switchable coupling, which is co-axially-arranged with the front end of the engine crankshaft. The switchable coupling is an integrated unit in which a crankshaft vibration damper, an engine accessory drive pulley and a disengageable clutch overlap such that the axial depth of the clutch-pulley-damper unit is nearly the same as a conventional belt drive pulley and engine damper. The front end motor-generator system includes an electrical energy store that receives electrical energy generated by the motor-generator when the coupling is engaged. When the coupling is disengaged, the motor-generator may drive the pulley portion of the clutch-pulley-damper to drive the engine accessories using energy returned from the energy store, independent of the engine crankshaft.