Crankcase Vacuum Control for Reducing Engine Particle Emissions
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Solution Overview
Problem
Internal combustion engines, particularly those using the Otto combustion process, face challenges in reducing particle number emissions due to reverse blow-by effects, where engine oil enters the combustion chamber, leading to high particle emissions during idling and overrun phases, as existing ventilation systems do not adequately manage pressure differences between the crankcase and combustion chamber.
Innovation Solution
A device comprising a crankcase, combustion chamber, and an oil separator connected via a line device with a pressure setting mechanism to reduce the pressure difference between the crankcase and combustion chamber, utilizing a control means like a shut-off valve to limit vacuum generation during idling and low-load conditions, thereby reducing oil entry into the combustion chamber and subsequent particle emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a throttle valve is closed except for a small gap during idling and overrun, then the engine can operate in low-load modes, but a negative pressure is created in the combustion chamber that causes reverse blow-by and oil accumulation
Solution Approach 1:
A pressure equalization line connects the combustion chamber to the crankcase, acting as an intermediary pathway that equalizes pressure between these two spaces. This prevents the negative pressure in the combustion chamber from sucking oil into the combustion chamber through the piston rings, thereby eliminating reverse blow-by while maintaining the closed throttle valve position during idling and overrun.
2Ease of operation
If the throttle valve remains closed during idling, then fuel metering is simplified, but oil accumulates in the combustion chamber leading to high particle emissions when load increases
Solution Approach 1:
The pressure equalization line serves as a mediator that allows the throttle valve to remain closed during idling without causing oil accumulation. By equalizing pressure between the combustion chamber and crankcase, it prevents oil from being drawn into the combustion chamber, thus avoiding the subsequent particle emission problem when load increases.
3Object-generated harmful factors
If crankcase ventilation is connected to the charge air supply line after the throttle valve, then a vacuum is generated in the crankcase to reduce particle emissions, but air may flow back into the crankcase under certain conditions
Solution Approach 1:
A check valve is introduced as an intermediary component in the ventilation line between the crankcase and the charge air supply line. This check valve allows air to flow from the combustion chamber side to the crankcase (creating vacuum for particle reduction) but prevents air from flowing back into the crankcase under reverse pressure conditions, thus ensuring reliable one-way ventilation.
4Object-generated harmful factors
If a pressure equalization line is added to prevent reverse blow-by, then oil entry into the combustion chamber is reduced, but the device complexity increases
Solution Approach 1:
The pressure equalization line is integrated into the existing crankcase ventilation system, allowing it to serve multiple functions: equalizing pressure between combustion chamber and crankcase, preventing reverse blow-by, and working in conjunction with the check valve to maintain proper ventilation. This multi-functionality reduces the need for separate dedicated components.
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 reduces reverse blow-by and subsequent particle emissions by generating a controlled vacuum in the crankcase, limiting oil entry into the combustion chamber, and optimizing particle number emissions during critical operating phases.
Implementation Method 1
at least one pressure setting device (17, 17.1, 17.2, 17.3) for setting a negative pressure in the crankcase (1) in order to reduce the pressure difference between the crankcase (1) and the combustion chamber (4)
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a device (V) for an internal combustion engine, in particular for generating a vacuum in a crankcase (1) and/or for venting a crankcase (1), comprising a crankcase (1), at least one combustion chamber (4), at least one oil separator (16.1) connected to the crankcase (1) and at least one pressure adjusting device (17.1), which is designed to adjust a vacuum in the crankcase (1) during operation, so that the pressure difference between the crankcase (1) and the combustion chamber (4) is advantageously reduced.