Venturi Nozzle PCV Flow Regulation
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Solution Overview
Problem
Conventional PCV systems face challenges in maintaining a constant flow rate over a range of pressure differentials, with spring-loaded valves being costly and noisy, and simple orifices providing inadequate flow regulation, necessitating a cost-effective solution for consistent crankcase ventilation.
Innovation Solution
The implementation of a venturi nozzle to regulate flow in the PCV system, which is low in cost and simple in design, maintaining a constant flow rate by reaching sonic flow velocity over most engine operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring-loaded PCV valve is used to regulate flow, then a generally constant flow rate is achieved above a certain pressure differential, but the cost is relatively higher and noise is generated at certain points of instability
Solution Approach 1:
The patent extracts the essential flow regulation function from the complex spring-loaded valve mechanism and implements it through a simple venturi nozzle geometry. The venturi nozzle achieves flow regulation purely through its shaped passage without requiring springs, valves, or moving parts, thereby eliminating noise and reducing cost while maintaining flow constancy.
Solution Approach 2:
The venturi nozzle is a simple, inexpensive geometric feature that can be easily manufactured into the PCV system housing. It replaces expensive mechanical valves with a low-cost flow restriction geometry that achieves the same flow regulation function without the associated costs and complexities.
2Device complexity
If a simple orifice is used in place of a PCV valve, then the design is relatively less complex and less expensive, but it provides less than ideal flow regulation for some of the range of pressure differentials
Solution Approach 1:
The venturi nozzle employs a specifically shaped passage with varying cross-sectional area along its length, creating different flow conditions at different locations. The converging section accelerates flow, the throat creates a restriction point, and the diverging section decelerates flow, thereby achieving superior flow regulation compared to a simple orifice while maintaining design simplicity.
3Device complexity
If a venturi nozzle is used to regulate flow, then cost is reduced and design is simplified while maintaining generally constant flow rate, but the nozzle must be precisely sized to reach sonic flow velocity
Solution Approach 1:
The venturi nozzle achieves flow regulation by changing the geometric parameters of the passage, specifically the cross-sectional area along the flow direction. By carefully selecting the throat area and passage geometry, the nozzle is designed to reach sonic flow velocity at the throat under typical operating conditions, thereby maintaining constant flow rate across a range of pressure differentials.
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 venturi nozzle ensures a consistent flow rate over a wide range of pressure differentials, improving crankcase ventilation efficiency and reducing emissions, while being more cost-effective and quieter than traditional solutions.
Implementation Method 1
a venturi nozzle to regulate flow in place of a spring-loaded PCV valve or a simple orifice
Implementation Method 2
The venturi nozzle is sized to reach sonic flow velocity during most of the vacuum pressure range of engine operation, thereby controlling PCV vapor flow at a constant value over most of the engine operating range
Data Source
AI summary
A positive crankcase ventilation system for an internal combustion engine is disclosed. The system includes an engine having a cylinder air intake system connected to associated cylinders and a filtered air inlet to a crankcase for admitting air to mix with crankcase vapors. A throttle is disposed in the cylinder air intake system for controlling airflow to the associated cylinders. The system further includes a venturi nozzle having an inlet and an outlet. The venturi nozzle inlet is connected to the crankcase for receiving the mixture of filtered air and crankcase vapors. The venturi nozzle outlet is connected to the cylinder air intake system at a location subject to variable intake vacuum pressure between the throttle and the cylinders to allow the mixture of filtered air and crankcase vapors to be drawn into the inlet air passing to the cylinders downstream of the throttle.