Hybrid Powertrain Torque Control for Stability Events
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Solution Overview
Problem
Existing hybrid powertrain control systems face challenges in efficiently managing torque inputs from internal combustion engines and electric machines to optimize fuel economy, emissions, and drivability, particularly in responding to operator inputs and varying operating conditions.
Innovation Solution
A method for controlling the internal combustion engine in a hybrid powertrain system that determines an accelerator output torque request and an allowable range of input torque, allowing the engine to meet preferred torque inputs within this range, while adjusting engine operation to stay within the allowable torque limits when preferred torque exceeds engine capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is controlled to meet the preferred input torque when within the allowable range, then fuel economy and emissions are optimized, but the system must also ensure the engine operates within the allowable torque range to maintain stability control and traction control
Solution Approach 1:
The control system dynamically adjusts the allowable torque range based on current operating conditions including stability control and traction control requirements. The method determines an allowable range of input torque that varies with operating conditions, allowing the engine to operate optimally when conditions permit while ensuring safety and control requirements are always met. This dynamic adaptation resolves the contradiction by making the torque range flexible rather than fixed.
Solution Approach 2:
The system changes the torque parameter limits based on detected operating conditions. When stability control or traction control events occur, the allowable torque range is adjusted to prevent wheel slip or loss of control. The control system monitors various parameters and modifies the acceptable torque operating window accordingly, enabling fuel optimization within safe and effective boundaries.
2Productivity
If the engine operates at preferred torque inputs for optimal efficiency, then fuel economy improves, but the system must respond quickly to operator inputs and maintain control during traction and stability events
Solution Approach 1:
The control system pre-determines the allowable torque range based on current operating conditions before actual torque application occurs. By calculating and establishing the boundaries of acceptable torque inputs in advance, the system can quickly respond to operator requests without needing to compute limits in real-time during transient events. This preliminary establishment of torque boundaries enables both efficient operation and rapid response.
3Loss of energy
If the control system tightly manages torque inputs to optimize fuel economy and emissions, then system efficiency improves, but the complexity of controlling multiple torque-generative devices increases
Solution Approach 1:
The control system acts as an intermediary that coordinates torque inputs from the internal combustion engine and electric machines. Rather than allowing direct, independent control of each torque-generative device, the system mediates their combined output through a unified control strategy that determines allowable torque ranges. This intermediary control layer simplifies the overall management of multiple devices while maintaining optimization of energy efficiency.
Data Source
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AI summary
An internal combustion engine (14) is mechanically coupled to a hybrid transmission (10) to transmit mechanical power to an output member (64). A method for controlling the internal combustion engine (14) includes determining an accelerator output torque request based upon an operator input to the accelerator pedal, and determining an axle torque response type. A preferred input torque from the engine (14) to the hybrid transmission (10) is determined based upon the accelerator output torque request. An allowable range of input torque from the engine (14) which can be reacted with the hybrid transmission (10) is determined based upon the accelerator output torque request and the axle torque response type. The engine (14) is controlled to meet the preferred input torque when the preferred input torque is within the allowable range of input torque from the engine (14). The engine (14) is controlled within the allowable range of input torque from the engine (14) when the preferred input torque is outside the allowable range of input torques from the engine (14).