Variable Compression Ratio Engine Tumble Flow Control
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Solution Overview
Problem
Variable compression ratio internal combustion engines face challenges in maintaining proper combustion conditions, especially at low compression ratios, due to difficulties in generating sufficient tumble flow, which affects combustion speed and thermal efficiency, leading to potential knocking and reduced performance.
Innovation Solution
A variable compression ratio internal combustion engine with a tumble flow strength controller that adjusts the strength of tumble flow in the combustion chamber according to the compression ratio, using mechanisms such as a tumble control valve and variable valve timing to enhance tumble flow generation, even at low compression ratios, thereby maintaining optimal combustion conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the compression ratio is reduced by increasing the combustion chamber height, then fuel economy and output performance are improved, but combustion speed decreases and thermal efficiency is reduced
Solution Approach 1:
The patent applies dynamics by making the compression ratio variable rather than fixed. The compression ratio changing mechanism dynamically adjusts the compression ratio based on operating conditions, allowing the engine to optimize between fuel economy/output performance (lower compression ratio) and combustion speed/thermal efficiency (higher compression ratio) in real-time, resolving the contradiction between these opposing requirements.
Solution Approach 2:
The patent changes the compression ratio parameter dynamically based on engine operating conditions. By using a compression ratio changing mechanism that adjusts the compression ratio according to load and speed requirements, the system can switch between high compression ratio for efficiency and low compression ratio for power output, thereby resolving the contradiction between combustion speed and output performance.
2Loss of energy
If the compression ratio is reduced by increasing the combustion chamber height, then fuel economy is improved, but thermal efficiency decreases and knocking occurs
Solution Approach 1:
The system dynamically adjusts the compression ratio based on operating conditions to maintain optimal thermal efficiency while improving fuel economy. The compression ratio changing mechanism allows the engine to operate at high compression ratios when thermal efficiency is critical and switch to lower compression ratios when fuel economy is the priority, resolving the contradiction between these two energy-related parameters.
Solution Approach 2:
The patent employs feedback control where the compression ratio is adjusted based on sensor inputs regarding engine operating conditions. This feedback mechanism ensures that the compression ratio is optimized in real-time to maintain thermal efficiency while achieving fuel economy improvements, preventing knocking and ensuring reliable operation across different operating points.
3Adaptability or versatility
If the combustion chamber height is increased to reduce compression ratio, then a squish area becomes difficult to form, but this is necessary for low compression ratio operation
Solution Approach 1:
The patent resolves this shape contradiction by making the compression ratio dynamic rather than relying on a fixed combustion chamber geometry. The compression ratio changing mechanism allows the system to achieve low compression ratios through mechanical adjustment rather than through increased combustion chamber height, thereby maintaining the squish area geometry while providing adaptability across a wide compression ratio range.
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
The solution effectively maintains proper combustion conditions across varying compression ratios by strengthening tumble flow, improving combustion efficiency and stability, and preventing knocking, without significantly impacting engine operating performance.
Implementation Method 1
a control to change the strength of a tumble flow in the combustion chamber according to a compression ratio in the internal combustion engine
Data Source
AI summary
In a variable compression ratio internal combustion engine that controls the compression of an internal combustion engine by changing the volume of the combustion chamber of the internal combustion engine in an axial direction of the cylinder, when a target compression ratio (εt) based on an operating condition of the internal combustion engine is at a reference compression ratio (ε0) or greater (S102), the compression ratio is changed to the target compression ratio (S103). When the target compression ratio (εt) is lower than the reference compression ratio (ε0) (S102), a control is executed to change the compression ratio and also to strength the tumble flow in the combustion chamber (S104).