Engine Torque Control via Air-Spark Transition
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Solution Overview
Problem
Existing vehicle powertrain control systems face challenges in maintaining accurate torque control, particularly when operating at or below the minimum torque required for combustion stability, leading to potential fuel wastage and degraded fuel economy due to clipping torque at a minimum torque limit.
Innovation Solution
A method is introduced where the vehicle controller transitions from air adjustment to spark adjustment during non-idle speed engine combustion operations, maintaining desired engine torque by reducing airflow while maintaining spark retard when torque is above the minimum, and using spark control when torque is below the minimum, ensuring accurate torque delivery even at low loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If torque is clipped at a minimum torque limit to ensure combustion stability, then combustion stability is maintained, but fuel economy deteriorates due to excessive spark retard and torque inaccuracies
Solution Approach 1:
The system dynamically transitions between air control and spark control modes based on operating conditions. When operating above minimum torque, air control is used; when operating at or below minimum torque, spark control takes over. This dynamic switching allows the system to maintain combustion stability while minimizing spark retard and improving fuel economy in low-load conditions.
Solution Approach 2:
The system changes the control parameter from air flow to spark timing when torque approaches the minimum limit. This parameter change allows continuous torque control below the minimum torque point by adjusting spark timing, thereby reducing excessive spark retard and improving fuel economy while maintaining combustion stability.
2Power
If air control is used to reduce torque when operating above minimum torque, then torque control is achieved, but combustion stability may be compromised when torque approaches minimum torque
Solution Approach 1:
The system implements a dynamic control strategy that switches between air control and spark control based on the operating point. When torque is above the minimum, air control is active; when torque approaches or goes below the minimum, the system transitions to spark control. This ensures continuous and stable torque control across the entire operating range while maintaining combustion stability.
Solution Approach 2:
The control system acts as an intermediary that manages the transition between air control and spark control. By introducing a hybrid control mode that combines both air and spark adjustments near the minimum torque point, the system ensures smooth torque control without compromising combustion stability.
3Reliability
If spark retard is increased to maintain combustion stability at low loads, then combustion stability is ensured, but fuel economy is degraded
Solution Approach 1:
The system changes the control parameter from air flow to spark timing when operating at or below minimum torque. By using spark control with minimal spark retard instead of excessive air control, the system reduces fuel consumption while maintaining combustion stability in low-load conditions.
Solution Approach 2:
The system uses feedback from torque sensing and operating condition monitoring to determine when to switch from air control to spark control. This feedback mechanism ensures that spark retard is applied only when necessary to maintain combustion stability, thereby minimizing fuel consumption.
Data Source
AI summary
Methods and systems are provided for engine torque control. Mutually exclusive airflow adjustments and spark adjustments are used to provide accurate engine torque control when operating near combustion stability limits. Torque offset values and proportional-integral control terms are adjusted responsive to tip-in/tip-out events to improve torque control response times.