Hybrid Powertrain Growl Mitigation via Torque Control
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Solution Overview
Problem
Hybrid powertrain systems experience noise, vibration, and harshness (NVH) issues due to conditions that enable 'growl,' a perceptible rumble caused by locked clutches with lash, which current control systems fail to effectively mitigate.
Innovation Solution
A method to control the hybrid powertrain by monitoring conditions conducive to growl and avoiding operation in regions where growl is possible by adjusting engine speed, engine torque, and motor torque to prevent clutch engagement in ranges that lead to NVH issues, using a control algorithm that assigns penalties for operating in undesirable regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the powertrain operates in regions that optimize fuel economy and emissions, then fuel efficiency is improved, but NVH issues (growl) occur due to locked clutches with lash
Solution Approach 1:
The control algorithm proactively identifies and avoids powertrain operating regions that would cause growl conditions before they occur. By predicting problematic regions based on engine speed, torque, and motor torque parameters, the system takes preventive action to steer operation away from these regions, thereby eliminating NVH issues before they manifest while maintaining fuel-efficient operation in acceptable regions.
Solution Approach 2:
The system dynamically adjusts operating parameters (engine speed, engine torque, motor torque) to transition the powertrain out of growl-prone regions. By modifying these parameters in real-time based on current operating conditions, the control algorithm shifts the operating point to regions that maintain fuel efficiency while avoiding the specific parameter combinations that trigger clutch lash and growl conditions.
2Object-affected harmful factors
If the control system restricts operation to avoid growl regions, then NVH issues are reduced, but the range of available operating regions is limited
Solution Approach 1:
The control algorithm dynamically adapts the avoidance strategy based on real-time operating conditions. Rather than imposing static restrictions, the system continuously evaluates current engine speed, torque, and motor torque conditions to determine whether to avoid specific regions. This dynamic approach allows the powertrain to access a broader range of operating regions when conditions permit, while only restricting operation in growl-prone regions when the specific conditions for growl are present.
3Use of energy by moving object
If current control systems manage torque distribution, then fuel economy and emissions are optimized, but they fail to prevent growl conditions caused by clutch lash
Solution Approach 1:
The control algorithm incorporates feedback mechanisms that continuously monitor powertrain operating conditions and adjust torque distribution accordingly. By feeding back information about current engine speed, torque, and motor torque levels, the system real-time optimizes torque management to simultaneously achieve fuel economy goals while preventing entry into growl conditions, thereby improving both fuel efficiency and drivability reliability.
Data Source
AI summary
A hybrid powertrain includes an engine, an electric machine, and a transmission. A method to control the powertrain includes monitoring operation of the powertrain, determining whether conditions necessary for growl to occur excluding motor torque and engine torque are present, and if the conditions are present controlling the powertrain based upon avoiding a powertrain operating region wherein the growl is enabled.