Cylinder-Specific Knock Control via Variable Liquid Additive Injection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current knock control methods in internal combustion engines, such as ignition angle retardation and water injection, face inefficiencies and risks, including increased exhaust gas temperatures and water consumption, which affect engine performance and safety.
Innovation Solution
A method for cylinder-specific knock control using variable water injection quantities and cycles, directly or indirectly into the combustion chamber, based on real-time engine parameters like knocking amplitude, load, speed, and temperature, to adjust the injection strategy and prevent knocking without permanent water usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ignition timing is retarded to control knocking, then knocking is reduced, but combustion efficiency decreases and exhaust gas temperature increases
Solution Approach 1:
A liquid additive medium is introduced as an intermediary substance between the fuel and combustion process. This additive is injected into the combustion chamber during the compression stroke, where it acts as a mediator to suppress knocking by modifying the combustion characteristics without requiring ignition timing retardation, thus preserving combustion efficiency.
Solution Approach 2:
The invention changes the chemical composition parameter of the combustion mixture by adding a liquid additive medium with specific properties (different from the fuel). This parameter change allows the combustion process to occur at the original ignition timing while suppressing knocking, thereby avoiding the energy losses associated with timing retardation.
2Reliability
If water injection is used continuously to prevent knocking, then knocking is suppressed, but water consumption increases significantly
Solution Approach 1:
Instead of continuous water injection, the invention employs periodic injection of the liquid additive medium only when knocking is detected. The control unit monitors knocking conditions and triggers injection events only during necessary periods, significantly reducing the total quantity of additive medium required while maintaining effective knocking suppression.
Solution Approach 2:
The system uses the engine's own operating parameters (knocking detection, temperature, load) to automatically control the injection timing and quantity of the additive medium. This self-regulating mechanism ensures that the additive is injected only when and where needed, optimizing the quantity used while maintaining knocking prevention.
3Reliability
If water injection is used to counteract knocking, then knock limit is shifted, but a significant portion of water enters the oil circuit posing risks
Solution Approach 1:
The invention uses a disposable liquid additive medium that is consumed in small quantities during combustion rather than reusing water that could contaminate the oil circuit. The additive medium is designed to be completely consumed or evaporated during the combustion process, eliminating the risk of entering the oil circuit and causing contamination.
Solution Approach 2:
The liquid additive medium serves as an intermediary substance that performs the knock-suppression function without the side effects of water injection. By using a specially formulated additive instead of water, the system achieves knock limit shifting while avoiding the harmful effect of water entering the oil circuit.
4Reliability
If large quantities of water are injected to shift the knock limit, then knocking is prevented, but transport requirements increase
Solution Approach 1:
The invention changes the physical and chemical parameters of the injected substance by using a liquid additive medium with higher energy density and different combustion properties compared to water. This parameter change allows achieving the same knock-prevention effect with much smaller injection quantities, thereby reducing the size and complexity of the transport and storage system required.
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 reduces water consumption, maintains engine efficiency, and lowers exhaust gas temperatures by precisely managing water injection, effectively shifting the knock limit without degrading combustion performance.
Implementation Method 1
Due to the cooling effect of the injected water evaporating
Implementation Method 2
the cooling effect of the injected water evaporating
Implementation Method 3
the knock-inhibiting effect of the resulting water vapor
Data Source
Figure 1
AI summary
The invention relates to a method for cylinder-specific knock control by injecting a liquid additive medium into at least one cylinder of a spark-ignition internal combustion engine, comprising the steps of: detecting knocking combustion in at least one cylinder of the internal combustion engine, determining the operating point of the internal combustion engine at a time (tK) in which knocking combustion is detected in the at least one cylinder of the internal combustion engine, activating the knock control, and delivering at least one injection event indirectly or directly into the combustion chamber of the at least one cylinder.According to the invention, a variable initial injection quantity (QE, QOffset) is determined depending on the detected operating point of the internal combustion engine at time (tK), which is injected in a first injection event (n = 1) in a first working cycle (in'; n = 1) of the at least one cylinder, and variable cycle parameters of a first control cycle are determined depending on the detected operating point of the internal combustion engine at the time in which knocking combustion is detected in the at least one cylinder of the internal combustion engine, after which the control cycle is carried out by terminating the first injection event and the at least one further injection event indirectly or directly into the combustion chamber of the at least one cylinder.