Hybrid Generator Torque Control for Engine Torsional Vibration
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Solution Overview
Problem
Range extended plug-in hybrid electric vehicles face disadvantages due to the need for additional mass in flywheels to mitigate torsional vibrations from reciprocating piston engines, which increases weight, reduces electric range, and negatively impacts performance and fuel economy.
Innovation Solution
An electronic controller uses a combustion model to predict torque variations from the reciprocating piston engine and adjusts the high voltage generator's operation to compensate for these variations, eliminating the need for a heavy flywheel by phase-shifting the torque required to drive the generator, utilizing a resilient rotary drive coupling with a flywheel of predefined inertia and a drive plate of lower inertia.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a heavy flywheel is added to reduce torsional vibrations, then engine operation smoothness is improved, but vehicle weight increases and electric range is reduced
Solution Approach 1:
The patent replaces the mechanical solution of adding a heavy flywheel with an electronic control system that uses a combustion model to predict torque variations and actively controls the generator torque in real-time. This substitution of mechanical inertia-based vibration reduction with electronic active control achieves the same smoothing effect without the weight penalty.
Solution Approach 2:
The system uses a combustion model that continuously receives inputs from engine sensors (crankshaft position, camshaft position, throttle position, etc.) to predict upcoming torque variations. This feedback loop allows the controller to preemptively adjust generator torque to counteract predicted engine torque fluctuations, maintaining smooth operation without additional mass.
2Stability of the object's composition
If a heavy flywheel is added to reduce torsional vibrations, then engine operation smoothness is improved, but performance and fuel economy are reduced
Solution Approach 1:
By replacing the heavy mechanical flywheel with an electronic control system, the patent eliminates the inertial penalty that would otherwise require additional energy for acceleration and reduce overall vehicle performance. The electronic system provides the same vibration reduction function without the trade-off in productivity.
Solution Approach 2:
The system dynamically adjusts generator torque in real-time based on predicted engine torque variations, allowing the vehicle to maintain optimal performance characteristics. Unlike a fixed heavy flywheel that constantly adds inertia, the electronic system provides adaptive, variable compensation that responds to changing operating conditions without permanent performance penalties.
3Object-affected harmful factors
If a heavy flywheel is added to reduce torsional vibrations, then the magnitude of vibrations is reduced, but the complexity of the system increases
Solution Approach 1:
The electronic controller performs multiple functions: it manages generator torque control, predicts torque variations using the combustion model, and compensates for vibrations. By making the controller multi-functional, the patent avoids adding separate dedicated vibration reduction hardware, thereby reducing overall system complexity despite the sophisticated control algorithm.
Solution Approach 2:
Replacing the simple but heavy mechanical flywheel with an electronic control system actually reduces overall system complexity in terms of physical components. The electronic solution uses software-based combustion modeling and control algorithms that can be implemented within existing controller hardware, avoiding the need for additional mechanical parts, mounting structures, and associated complexity.
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 solution reduces the mass added to the vehicle, maintains smooth engine operation, and enhances performance and fuel efficiency by minimizing the need for additional weight, while effectively managing torsional vibrations without a heavy flywheel.
Implementation Method 1
a high voltage electrical generator driven via a coupling by the reciprocating piston engine
Implementation Method 2
a resilient rotary drive coupling with a flywheel of predefined inertia and a drive plate of lower inertia
Implementation Method 3
a flywheel of predefined inertia fastened to one end of a crankshaft
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A range extended plug-in hybrid electric vehicle 5 is disclosed having a high voltage electric generator 22 driven by a reciprocating piston engine 10 via a coupling 11 that includes a flywheel 11F fastened to a crankshaft 10C of the reciprocating piston engine 10, a resilient rotary drive 11S and a drive plate 11D driveably connected to an input shaft 22S of the high voltage electric generator 22. An electronic controller 31 is used to model variations in output torque (T) from the reciprocating piston engine 10 and control the driving torque (G) required for the high voltage electric generator 22 based upon the modelled torque variations.