Engine Compression-End Pressure Control via Variable Compression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In multi-cylinder engines, adjusting the valve-closing timing of the exhaust valve to decrease compression-end pressure can lead to a decrease in air filling amount in the combustion chamber, increasing the concentration of fuel gas and causing abnormal combustion.
Innovation Solution
A compression-end pressure control device that includes a variable compression device and an exhaust valve-adjusting device, which adjusts the supply amount of a pressurized working fluid and the valve-closing timing to maintain optimal compression ratios and prevent abnormal combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the valve-closing timing of the exhaust valve is delayed to decrease compression-end pressure, then the compression-end pressure decreases, but the air filling amount in the combustion chamber decreases and fuel gas concentration increases causing abnormal combustion
Solution Approach 1:
The patent separates the control of compression-end pressure from exhaust valve timing adjustment by introducing a variable compression ratio mechanism. This allows independent control of compression-end pressure through compression ratio adjustment while maintaining optimal exhaust valve timing for stable combustion.
Solution Approach 2:
The patent changes the compression ratio parameter to control compression-end pressure instead of changing the exhaust valve timing parameter. This parameter substitution allows pressure control without affecting air filling amount and fuel gas concentration.
2Productivity
If the compression ratio is increased to improve combustion efficiency, then the compression-end pressure increases, but the concentration of fuel gas relative to gas in the combustion chamber increases leading to abnormal combustion
Solution Approach 1:
The patent introduces a variable compression ratio mechanism that can dynamically adjust the compression ratio based on operating conditions. This allows the system to optimize combustion efficiency while preventing abnormal combustion by maintaining appropriate fuel gas concentration levels.
Solution Approach 2:
The patent employs a control system that monitors combustion conditions and adjusts the compression ratio accordingly. This feedback mechanism prevents abnormal combustion by regulating compression ratio to maintain safe fuel gas concentration levels while optimizing combustion efficiency.
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 device effectively decreases compression-end pressure without reducing air charge, preventing abnormal combustion by controlling the concentration of gaseous fuel in the combustion chamber.
Implementation Method 1
a variable compression device that increases a compression ratio of a combustion chamber by supplying a pressurized working fluid to a fluid chamber
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A compression-end pressure control device (300) is disclosed for controlling a supply amount of a pressurized working fluid for a variable compression device, the variable compression device that increases a compression ratio of a combustion chamber (R1) by supplying the working fluid to a fluid chamber (R3), the compression-end pressure control device (300) including: a compression ratio-setting device (305) that decreases a compression ratio of the combustion chamber (R1) by controlling the variable compression device in the case where a compression end pressure acquired in the combustion chamber (R1) is higher than a reference range determined in advance; and a variable compression device adjusting device (306) that controls a supply amount of the working fluid based on the compression ratio determined by the compression ratio-setting device (305).