Active Purge Pump Control for Turbocharged Engine Stability
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Solution Overview
Problem
The conventional purge system struggles to generate negative pressure at the intake valve of engines with turbochargers, making it difficult to apply the active purge system effectively, leading to issues with fuel-rich or lean combustion atmospheres and engine instability.
Innovation Solution
A method that calculates the purge concentration of fuel evaporation gas using the revolutions per minute (RPM) of the purge pump and pressure at its rear end, determines the target purge flow rate, and controls the purge valve to accurately adjust the fuel amount, employing a diffusion/delay model to estimate the flow rate and concentration of the purge gas as it reaches the intake manifold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the conventional purge system uses intake negative pressure to supply evaporation gas, then the system structure is simple, but it cannot generate sufficient negative pressure at the intake valve in turbocharged engines
Solution Approach 1:
The patent introduces an active purge system that segments the purge function from the conventional passive intake negative pressure system. A dedicated purge pump is added to actively supply purge gas, while the conventional system remains for non-turbocharged engines or supplementary operation. This segmentation allows turbocharged engines to overcome the negative pressure generation limitation while maintaining compatibility with conventional systems where applicable.
Solution Approach 2:
The patent introduces an active purge pump as an intermediary device between the canister and intake manifold. This mediator actively transports purge gas through the purge passage, overcoming the insufficient negative pressure at the intake valve in turbocharged engines. The pump serves as a bridge that enables effective purge operation in high-performance engine configurations.
2Reliability
If the purge gas flow rate is not accurately controlled, then the system operation is simple, but the combustion atmosphere becomes too lean or rich causing engine instability
Solution Approach 1:
The patent implements a feedback control mechanism where the controller continuously monitors engine operating conditions and adjusts the purge valve opening degree accordingly. The controller calculates the appropriate purge gas flow rate based on engine load, speed, and other parameters, then modulates the purge valve to achieve the target flow rate. This closed-loop feedback ensures stable combustion by preventing overly lean or rich conditions while maintaining relatively simple system architecture.
Solution Approach 2:
The patent employs dynamic control of the purge valve opening degree to adapt purge gas flow rates to varying engine operating conditions. Rather than using a fixed opening, the valve dynamically adjusts its position based on real-time engine parameters, enabling the system to maintain optimal combustion atmosphere across different operating regimes without requiring complex additional hardware.
3Measurement precision
If the purge concentration is not accurately calculated, then the calculation process is simple, but the fuel amount control becomes inaccurate leading to engine oscillation and idle instability
Solution Approach 1:
The patent replaces physical concentration sensors with a computational model that calculates purge concentration based on measurable parameters such as purge pump operating time, purge valve opening degree, and engine operating conditions. This substitution of mechanical sensing with computational estimation achieves accurate concentration measurement without adding complex sensor hardware, thereby improving measurement precision while controlling system complexity.
Solution Approach 2:
The patent introduces a diffusion/delay model as an intermediary computational layer between the purge system operation and the fuel control system. This model estimates the concentration and arrival time of purge gas at the intake manifold by considering diffusion effects and transport delays through the purge passage. The mediator model enables accurate fuel compensation without requiring direct concentration measurement, resolving the contradiction between precision and complexity.
4Loss of time
If the purge gas travels through a long passage to reach the intake manifold, then the system design is simple, but there is a time delay that makes real-time control difficult
Solution Approach 1:
The patent implements preliminary calculation of purge gas arrival time and concentration using the diffusion/delay model before the actual purge gas reaches the intake manifold. By estimating these parameters in advance based on purge pump operation duration, flow rates, and passage characteristics, the system can prepare appropriate fuel compensation actions ahead of time, effectively compensating for the transport delay without adding complex real-time sensing infrastructure.
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 method allows for precise control of the fuel amount, preventing engine oscillation faults, idle instability, and engine stalls by accurately calculating and reflecting the purge concentration in the fuel control, ensuring stable combustion.
Implementation Method 1
calculating, by a controller, a purge concentration of the purge gas by using the revolutions per minute (RPM) of the purge pump, and a pressure at the rear end of the purge pump
Implementation Method 2
determining, by the controller, the concentration of the purge gas flowing into an intake system by using a diffusion/delay model of the purge gas until being discharged by the purge pump and flowing into the intake system of an engine through a purge passage
Implementation Method 3
The fuel stored in a fuel tank of a vehicle is evaporated according to the flow and the internal temperature in the fuel tank to generate a fuel evaporation gas
Data Source
AI summary
A purge concentration calculation control method in an active purge system for purging a fuel evaporation gas by using a purge pump may include: calculating the purge concentration by using the RPM of the purge pump, and the pressure at a rear end of the purge pump; and controlling a purge valve in order to satisfy a target purge flow rate and the purge fuel amount by using the calculated purge concentration.