Internal Combustion Engine Exhaust Duct Pressure Wave Tuning
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Solution Overview
Problem
Previous internal combustion engine designs face challenges in ensuring complete filling of the cylinder with the air-fuel mixture during the induction stroke and complete scavenging of exhaust gases during the exhaust stroke, leading to reduced power output and fuel efficiency.
Innovation Solution
The exhaust duct is tuned to harness energy and pressure waves in the exhaust flow to aid cylinder filling and scavenging by creating negative or positive pressure waves, which are used to enhance the dynamics and flow of inlet fluid, and the combustion chamber is designed to allow the chamber valve to be significantly open at top dead centre, allowing for efficient fluid movement and combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional valve and duct designs are used, then the engine structure is simple, but the cylinder cannot be completely filled with air-fuel mixture and cannot be completely scavenged of exhaust gases
Solution Approach 1:
The exhaust duct is designed to create negative pressure waves before the induction stroke begins, preparing the cylinder for efficient filling. The duct geometry is predetermined to generate pressure waves at specific times in the cycle, advancing the filling action before the piston reaches top dead centre.
Solution Approach 2:
The exhaust duct is tuned to generate periodic pressure waves that synchronize with the engine cycle. These waves are created at regular intervals corresponding to each exhaust stroke, utilizing the periodic nature of engine operation to enhance filling and scavenging efficiency continuously.
2Productivity
If the chamber valve is kept closed to maintain compression, then compression ratio is maintained, but the cylinder cannot be efficiently filled and scavenged
Solution Approach 1:
The exhaust duct creates negative pressure waves before the induction stroke begins, preparing the cylinder for efficient filling. The duct geometry is predetermined to generate pressure waves at specific times in the cycle, advancing the filling action before the piston reaches top dead centre.
Solution Approach 2:
The exhaust duct is tuned to generate periodic pressure waves that synchronize with the engine cycle. These waves are created at regular intervals corresponding to each exhaust stroke, utilizing the periodic nature of engine operation to enhance filling and scavenging efficiency continuously.
3Productivity
If the exhaust duct is tuned to create negative pressure waves, then cylinder filling is improved, but the exhaust duct design becomes more complex
Solution Approach 1:
The exhaust duct is tuned by adjusting specific geometric parameters including length, diameter, and curvature to optimize pressure wave generation. By carefully selecting these parameters, the duct creates negative pressure waves that enhance cylinder filling without requiring complex additional components.
Solution Approach 2:
The exhaust duct features asymmetric geometry with varying cross-sectional areas and curved sections designed to generate specific pressure wave patterns. This asymmetric design allows the duct to create the desired negative pressure waves while maintaining a relatively simple single-duct structure.
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 design improves cylinder filling and scavenging efficiency, enabling better power output and fuel efficiency by utilizing the momentum and pressure waves to facilitate the flow of fluids, allowing for lean burn operation and high compression ratios.
Implementation Method 1
the exhaust duct is tuned to accelerate the inlet fluid when the piston is near the top of its stroke, and to create negative pressure in the cylinder to aid cylinder filling with inlet fluid, through at least part of the induction stroke, by harnessing energy in the flow of exhaust fluid
Implementation Method 2
harnessing energy in the flow of exhaust fluid
Implementation Method 3
the exhaust duct is tuned to harness energy and pressure waves in the exhaust flow to affect the dynamics and/or flow of inlet fluid to aid scavenging of the cylinder using reflected negative pressure waves from the exhaust flow
Implementation Method 4
the exhaust duct is tuned to harness energy and pressure waves in the exhaust flow to affect the dynamics and/or flow of inlet fluid to assist cylinder filling using reflected positive pressure waves
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An internal combustion engine (10) includes at least one cylinder (12) having a piston, and a cylinder head containing an inlet duct (3) incorporating an inlet valve 1 to allow flow in only one direction and an exhaust duct incorporating no mechanical flow restricting device and at least one chamber valve (2) through which both inlet and exhaust fluids pass from the ducts (3,4) into and out of the cylinder (12), and a combustion chamber (6) in the cylinder (12) that allows the chamber valve (2) to be significantly open when the piston (5) is at top dead centre enabling a transfer of fluid, fluid flow pressure and pressure waves between the cylinder, and the inlet (3) and exhaust ducts (4).