Hybrid Vehicle Torque Control for Lean Combustion Shock
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Solution Overview
Problem
In hybrid vehicles, lean combustion of the internal combustion engine leads to increased torque variation, reducing the torque down amount and making it difficult to achieve sufficient torque reduction during speed changes, which can result in torque shock and durability issues.
Innovation Solution
A control apparatus for hybrid vehicles that determines the air-fuel ratio of the internal combustion engine before speed changes and adjusts it to be leaner, allowing for increased torque down by either enhancing the electric motor's output distribution or enriching the air-fuel ratio to increase the torque down capability, thereby mitigating torque shock and durability problems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lean combustion is performed in the internal combustion engine to improve fuel consumption efficiency, then fuel efficiency is improved, but torque variation increases and torque down amount decreases
Solution Approach 1:
The control apparatus predicts speed change timing in advance and performs preliminary torque down control by adjusting ignition timing or fuel injection before the actual speed change occurs. This preliminary action ensures sufficient torque reduction capability is maintained even during lean combustion, preventing torque shock while preserving fuel efficiency benefits.
Solution Approach 2:
The control system dynamically adjusts ignition timing and fuel injection parameters based on real-time detection of speed change conditions and air-fuel ratio. During lean combustion, the system flexibly modifies combustion control strategies to maintain adequate torque down capability when speed change is predicted, while returning to optimal lean combustion control when speed change is not imminent.
2Reliability
If torque down control is performed during speed change to prevent torque shock, then torque shock is prevented, but in lean combustion the torque cannot be reduced enough due to increased torque variation
Solution Approach 1:
The control apparatus detects speed change timing in advance and performs preliminary torque down control by adjusting ignition timing or fuel injection parameters before the speed change occurs. This advance preparation ensures sufficient torque reduction capability is available even during lean combustion, effectively preventing torque shock while maintaining torque down effectiveness.
Solution Approach 2:
The control system changes combustion parameters (ignition timing, fuel injection amount) based on detected speed change conditions and air-fuel ratio. During lean combustion with predicted speed change, the system adjusts these parameters to maintain adequate torque down capability, effectively resolving the contradiction between torque shock prevention and torque down effectiveness.
3Use of energy by moving object
If the air-fuel ratio is kept lean to maintain fuel efficiency, then fuel efficiency is maintained, but torque variation increases causing reduction in torque down amount
Solution Approach 1:
The control system dynamically adjusts ignition timing and fuel injection parameters based on real-time detection of speed change conditions while maintaining lean air-fuel ratio. This dynamic adjustment stabilizes torque output during lean combustion by compensating for torque variation through predictive control, allowing fuel efficiency to be maintained without excessive torque fluctuation.
Solution Approach 2:
The control apparatus changes combustion parameters (ignition timing, fuel injection amount) in response to detected speed change conditions while maintaining lean air-fuel ratio. These parameter adjustments reduce torque variation during lean combustion, ensuring both fuel efficiency is maintained and torque stability is improved when needed.
Data Source
AI summary
A control apparatus for a hybrid vehicle is provided with: an air-fuel ratio determinator configured to determine an air-fuel ratio of an internal combustion engine in a predetermined period until speed change by a transmission is actually performed; and a controller configured to control at least one of the internal combustion engine and an electric motor in such a manner that a possible amount of torque down of the internal combustion engine is increased if the air-fuel ratio of the internal combustion engine is lean in the predetermined period. By this, it is possible to avoid a detrimental effect, such as a torque shock, deterioration of durability of a friction material, and the like, which can occur in the speed change.