Front End Motor-Generator System for High Torque Hybrid Engines
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Solution Overview
Problem
Existing hybrid electric vehicle systems face challenges in scaling up drive train components to handle high torque outputs of large engines, interdependence of engine and motor-generator operation, and inability to independently meet accessory loads without auxiliary power units, which are costly and space-constrained.
Innovation Solution
A front end motor-generator system with a motor-generator laterally offset from the engine crankshaft, supported by a torque transfer segment, and a switchable coupling that allows flexible torque transfer between the engine and motor-generator, enabling independent operation of engine accessories and reducing fuel consumption and emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If starter-generators are mounted at the front end of large internal combustion engines, then the system can serve both as generator and engine starter reducing weight and cost, but the electric motor must be larger to handle much higher torque demands making the system weight, size and cost prohibitive
Solution Approach 1:
The system separates the starter and generator functions into distinct electric motors rather than using a single integrated starter-generator. This allows each motor to be optimized for its specific function and sized appropriately, avoiding the need for an oversized motor that would be required if a single unit had to handle both high-torque starting and generation functions.
Solution Approach 2:
A belt drive system is introduced as an intermediary between the electric motors and the engine crankshaft. This belt drive acts as a torque multiplier, allowing smaller electric motors to generate the high torque needed for starting large engines without requiring the motors themselves to be oversized.
2Force
If thicker and broader drive belts and pulleys are used to handle high torque demands, then the belt drive can transfer sufficient torque, but the belts and pulleys become so much larger and heavier that they are weight, size and cost prohibitive
Solution Approach 1:
The system replaces direct mechanical coupling with a belt drive system that uses friction and tension rather than rigid mechanical connection. This allows torque to be transferred effectively without requiring excessively large and heavy components, as the belt drive can be optimized for the specific torque requirements.
3Productivity
If hybrid electric systems use rear-end motor-generator integration, then the motor-generator can deliver torque directly to the driveline and be directly driven during regenerative braking, but the systems face challenges scaling up components to handle high torque outputs of large engines
Solution Approach 1:
A torque transfer segment with gear reduction is introduced as an intermediary between the front-end motor-generator and the engine accessories. This gear reduction system allows the motor-generator to operate at optimal speeds while delivering appropriate torque to various accessories, simplifying the scaling challenge by decoupling motor speed from accessory speed.
Solution Approach 2:
The system moves the motor-generator from traditional rear-end integration to front-end mounting on the engine, changing the spatial dimension of integration. This front-end position provides better access for large engines and allows the motor-generator to drive accessories directly through the torque transfer segment, avoiding the scaling issues associated with rear-end integration in large engine applications.
4Adaptability or versatility
If auxiliary power units are used to meet accessory loads independently, then the system can operate without the vehicle engine, but auxiliary power units are costly and space-constrained
Solution Approach 1:
The motor-generator system is designed to perform multiple functions: it can generate electrical power when the engine is running, drive accessories independently when the engine is off, and provide torque assistance during vehicle operation. This multi-functionality eliminates the need for separate auxiliary power units, reducing both cost and space requirements while maintaining the capability to operate accessories independently.
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.