EGR Device Helmholtz Resonance Engine Emissions
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Solution Overview
Problem
Existing exhaust gas re-circulation mechanisms in saddle-type vehicles with catalytic devices in the exhaust pipe face reduced pressure differences due to exhaust pulsation, making it difficult for exhaust gas to recirculate into the combustion chamber, which affects fuel efficiency and NOx reduction.
Innovation Solution
The exhaust gas re-circulation device includes a storage container and vent pipe that fluctuates internal pressure based on Helmholtz resonant frequency, allowing easy intake and discharge of exhaust gas during the intake stroke after the top dead center, increasing the EGR ratio and fuel efficiency even with a catalytic device present.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a catalytic device is provided in the exhaust pipe, then exhaust gas emissions are reduced, but the pressure difference in exhaust pulsation is reduced making EGR difficult
Solution Approach 1:
The exhaust system is segmented into two functional zones: the catalytic device for emission control and the gas storage chamber for EGR. The vent pipe creates a separate pressure fluctuation zone that connects the storage chamber to the combustion chamber, allowing EGR to operate independently from the catalytic device's pressure effects.
Solution Approach 2:
The gas storage chamber acts as an intermediary between the exhaust pipe and the combustion chamber. It stores exhaust gas and uses the vent pipe to create pressure-driven flow that overcomes the reduced pressure difference caused by the catalytic device, enabling reliable EGR.
2Object-generated harmful factors
If exhaust gas recirculation is increased, then NOx is reduced, but it becomes difficult to maintain high EGR ratio with catalytic device
Solution Approach 1:
Exhaust gas is stored in the gas storage chamber during the exhaust stroke while the exhaust valve is open, preparing the EGR medium in advance. The vent pipe then utilizes pressure fluctuations to discharge this pre-stored exhaust gas into the combustion chamber during the intake stroke, ensuring sufficient EGR ratio is achieved.
3Object-affected harmful factors
If catalytic device is installed, then emissions are cleaned, but fuel efficiency deteriorates due to reduced EGR
Solution Approach 1:
The system segments emission control and EGR functions into separate components (catalytic device and gas storage chamber with vent pipe), allowing both to operate simultaneously without interfering with each other, thus maintaining fuel efficiency while achieving emission cleanup.
Solution Approach 2:
The gas storage chamber and vent pipe system acts as an intermediary that restores the EGR function compromised by the catalytic device, enabling the system to maintain both emission control and fuel efficiency through adequate exhaust gas recirculation.
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 solution enhances fuel efficiency and reduces NOx emissions by ensuring more exhaust gas enters the combustion chamber, maintaining a higher EGR ratio and minimizing unburned components, even when a catalytic device is used in the exhaust pipe.
Implementation Method 1
the exhaust gas re-circulation device includes a storage container and a vent pipe arranged to communicate the storage container and the exhaust port. Internal pressure fluctuates based on a Helmholtz resonant frequency. Exhaust gas enters the storage container while an exhaust valve is open in an exhaust stroke, and is discharged into the combustion chamber from the storage container while the exhaust valve is open in an intake stroke
Data Source
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AI summary
A straddle-type vehicle (1) according to the present invention includes a single-cylinder four-cycle engine (10). The engine (10) includes an exhaust gas re-circulation device (101). The exhaust gas re-circulation device (101) is communicated with an exhaust port (31). The exhaust gas comes into the storage container (100) in the exhaust gas re-circulation device (101) when the exhaust valve (32) is open in an exhaust stroke. When the exhaust valve (32) is open in an intake stroke after the top dead center, the exhaust gas is discharged from the storage container (100) into the combustion chamber (40).