Engine Knock Control via Effective Octane and Fluid Injection
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Solution Overview
Problem
Existing engine control methods for alcohol-fueled engines, which consider only the inherent octane number, lead to overconsumption and complex calculations due to the non-linear relationship between fuel composition and octane number, resulting in inefficient fuel usage and frequent refueling.
Innovation Solution
A method that adjusts ignition spark timing and fluid injection based on the inherent octane, dilution, and evaporation effects of the fuel, using a combination of direct and port injection, with adjustments made according to engine operating conditions and molar composition to optimize fuel economy and knock control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuel injection is controlled based only on inherent octane number, then engine knock can be addressed, but fuel overconsumption occurs and refueling frequency increases
Solution Approach 1:
The patent changes the control parameters from considering only inherent octane number to considering multiple parameters including dilution effect and evaporation effect. This allows for more accurate fuel injection control that accounts for the actual cooling and knock-mitigating properties of the fuel, preventing overconsumption while maintaining reliable knock control.
Solution Approach 2:
The system uses feedback from knock sensors and engine operating conditions to dynamically adjust fuel injection amounts. By monitoring actual engine knock and adjusting injection based on the combination of octane, dilution, and evaporation effects, the system optimizes fuel usage while maintaining knock control.
2Reliability
If spark timing is retarded to address engine knock, then knock is controlled, but engine efficiency and fuel economy deteriorate
Solution Approach 1:
The patent changes the approach by not relying solely on spark timing retardation. Instead, it uses fuel injection control based on a comprehensive model including dilution effect and evaporation effect to address knock, allowing spark timing to be maintained at more efficient settings while still controlling knock.
Solution Approach 2:
The patent introduces the concept of an effective octane number that combines inherent octane, dilution effect, and evaporation effect as an intermediary parameter. This allows the system to control knock through fuel composition adjustments rather than relying primarily on spark timing changes, thereby preserving engine efficiency.
3Measurement precision
If the non-linear relationship between fuel composition and octane number is considered, then accurate knock control is achieved, but calculation complexity increases
Solution Approach 1:
The patent transforms the non-linear relationship into a linear model by introducing the effective octane number concept that combines inherent octane, dilution effect, and evaporation effect in a linear fashion. This simplifies the calculations while maintaining accuracy in predicting knock resistance based on fuel composition.
Solution Approach 2:
The patent segments the octane number determination into distinct components: inherent octane, dilution effect, and evaporation effect. Each component can be calculated separately and then combined linearly to determine the effective octane number, simplifying the overall calculation process while maintaining precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves engine fuel economy by judiciously using spark retard and knock control fluid injection, addressing engine knock while providing desired engine dilution, thereby reducing fuel consumption and optimizing engine performance.
Implementation Method 1
an injected fuel may also have a charge cooling effect that depends on the composition of the fuel
Implementation Method 2
alcohol fuels may also have a higher charge cooling effect that is not represented in the octane number
Implementation Method 3
an injected fuel may also have a charge cooling effect and an engine dilution effect that depends on the composition of the fuel
Data Source
AI summary
Methods and systems are provided for improving fuel usage while addressing knock by adjusting the use of spark retard and direct injection of a knock control fluid based on engine operating conditions and the composition of the injected fluid. One or more engine parameters, such as EGR, VCT, boost, throttle position, and CMCV, are coordinated with the direct injection to reduce torque and EGR transients.