Hybrid Powertrain Engine Load Control for Misfire Prevention
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Solution Overview
Problem
In hybrid electric vehicle powertrains, if the minimum engine load is not tightly controlled, it can lead to misfire conditions and overcharging of the battery, as the engine torque can vary unpredictably due to electronic throttle control algorithms, affecting fuel efficiency and emissions.
Innovation Solution
A method is implemented to monitor engine load using a mass air flow sensor signal, adjusting the minimum allowable torque limit and employing a minimum engine torque adder to maintain stable combustion, using a ramp and hold technique or proportional-integral control to prevent over-correction and ensure engine stability at low loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the minimum engine load is not tightly controlled, then the engine can operate more freely according to driver demand, but misfire conditions occur and battery overcharging happens
Solution Approach 1:
The system continuously monitors engine load conditions and compares the measured load against a calibrated minimum load threshold. When the load falls below the threshold, the control algorithm automatically adjusts the minimum torque limit to prevent misfire conditions and battery overcharging, creating a closed-loop feedback control system that maintains reliable operation while allowing flexible engine management.
Solution Approach 2:
The minimum torque limit is not fixed but dynamically adjusted based on real-time engine load conditions. The control system modifies the torque limit parameter in response to changing operating conditions, allowing the engine to operate freely when conditions are favorable while preventing misfire and overcharging when load becomes too low.
2Speed
If electronic throttle control is used to meet driver demand, then vehicle responsiveness improves, but minimum engine load varies unpredictably causing misfire
Solution Approach 1:
The control system takes preliminary action by establishing a minimum torque limit before the engine load can drop too low. When the measured load approaches the minimum threshold, the system proactively adjusts the torque limit to prevent misfire conditions from occurring, countering the unpredictable torque variations caused by electronic throttle control.
Solution Approach 2:
The minimum torque limit acts as an intermediary parameter between the electronic throttle control system and the engine combustion system. It mediates the relationship by providing a buffer that smooths out unpredictable torque variations while still allowing the electronic throttle to respond quickly to driver demands.
3Use of energy by moving object
If the engine operates at very low load, then fuel economy improves, but battery overcharging occurs
Solution Approach 1:
The control system monitors engine load and provides feedback to adjust the minimum torque limit, preventing operation at loads that would cause battery overcharging. This feedback mechanism allows the engine to operate at efficient low loads when appropriate while automatically preventing conditions that would harm the battery.
Solution Approach 2:
The system changes the minimum torque parameter dynamically based on operating conditions. When conditions indicate risk of battery overcharging, the parameter is adjusted to maintain a safe minimum load, balancing fuel economy goals with battery protection requirements.
Data Source
AI summary
A control method is disclosed for maintaining a calibrated minimum load for an engine in a vehicle powertrain with an engine. The possibility of engine misfire due to low engine loads is reduced. Further, undesired high temperature of an engine exhaust gas catalytic converter due to prolonged operation of the powertrain at low engine loads is avoided.