Intake Valve Timing Control for Spark Ignition Engine Efficiency
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Solution Overview
Problem
Spark ignited internal combustion engines with high geometric compression ratios face challenges in operating efficiently without causing abnormal combustion such as knocking and pre-ignition, as existing methods either compromise efficiency or require excessively broad intake valve closing timing adjustments that are not responsive enough to changing conditions.
Innovation Solution
A system and method that adjust the intake valve closing timing based on specific formulas to regulate air charge in the combustion chamber, retarding the closing timing to a most retarded crank angle that satisfies certain geometric compression ratio conditions, allowing for higher compression ratios while preventing abnormal combustion, and advancing the timing as needed to maximize air charge and power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the geometric compression ratio is increased to improve engine efficiency, then the expansion ratio is increased to convert heat more effectively, but the temperature in the cylinder around compression top dead center becomes excessively high causing knocking and pre-ignition
Solution Approach 1:
The patent applies variable valve timing to dynamically adjust the intake valve closing timing based on operating conditions. By retarding the intake valve closing timing under high-load low-speed conditions, the effective compression ratio is reduced to prevent abnormal combustion while maintaining the high geometric compression ratio for improved efficiency. This dynamic adjustment allows the engine to adapt between high efficiency mode and abnormal combustion prevention mode.
Solution Approach 2:
The patent changes the effective compression ratio parameter by adjusting the intake valve closing timing. While the geometric compression ratio remains high (improving efficiency), the effective compression ratio is reduced through late intake valve closing (preventing knocking and pre-ignition). This parameter transformation allows simultaneous achievement of both high efficiency and abnormal combustion prevention.
2Object-affected harmful factors
If the intake valve closing timing is retarded to reduce cylinder air charge and prevent abnormal combustion, then knocking and pre-ignition are avoided, but the air charge volume in the cylinder is reduced
Solution Approach 1:
The system dynamically adjusts the intake valve closing timing based on real-time operating conditions. Under high-load low-speed conditions where abnormal combustion risk is high, the timing is retarded to reduce air charge. Under other conditions, the timing is advanced to maximize air charge and power output. This dynamic control allows the system to optimize between abnormal combustion prevention and air charge volume based on current engine state.
3Adaptability or versatility
If the intake valve closing timing is broadly varied to secure sufficient power output while avoiding abnormal combustion, then both power and efficiency are maintained, but the control system complexity increases
Solution Approach 1:
The patent controls the intake valve closing timing parameter to achieve different effective compression ratios. By retarding the closing timing, the effective compression ratio is reduced to prevent abnormal combustion. By advancing the timing, the effective compression ratio is increased to maximize power output. This single parameter control provides broad adaptability across different operating conditions.
Solution Approach 2:
The system uses feedback from operating conditions (load, speed, temperature) to determine the optimal intake valve closing timing. The controller adjusts the timing based on detected conditions to maintain optimal effective compression ratio, preventing abnormal combustion while maximizing power output. This feedback mechanism enables adaptive control without requiring overly complex mechanical structures.
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
Enables higher geometric compression ratios with improved engine operating efficiency and prevention of abnormal combustion, specifically for fuels with octane numbers 88 RON, 91 RON, and 95 RON, by optimizing the intake valve closing timing to maintain effective compression ratios below thresholds that prevent knocking and pre-ignition.
Implementation Method 1
a spark plug which is arranged on the cylinder head and makes a spark in the combustion chamber
Implementation Method 2
a fuel injector which directly injects fuel into the combustion chamber
Implementation Method 3
the combustion of air fuel mixture has generated
Data Source
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AI summary
There is provided, in one aspect of the present description, an internal combustion engine system. In one example, the system comprises a controller configured to control an intake valve closing timing varying mechanism to vary a closing timing of the intake valve to regulate air charged in a combustion chamber in accordance with engine operating conditions and, in a first engine operating condition where a least volume of air is required to be charged into the combustion chamber, retard a closing timing of the intake valve to a most retarded crank angle which is after bottom dead center during a cylinder cycle and satisfies the following formulas: α >= - 0.2685 x ε02 + 10.723 x ε0 + 15.815 and ε0 >= 11.0, where α is the most retarded crank angle and ε0 is a geometric compression ratio of the engine.