Hybrid Engine Operating Point Control for Fuel Vapor Purge
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Solution Overview
Problem
Conventional power output apparatuses in hybrid vehicles face challenges in efficiently purging a large amount of fuel vapor from the fuel vapor trap without negatively impacting fuel economy, especially when the intake manifold negative pressure is low.
Innovation Solution
The apparatus includes a controller that sets a purge priority operating point to increase intake manifold negative pressure, allowing for faster purging of fuel vapor by adjusting the internal combustion engine's operating point to higher rotational speed with smaller torque when a high fuel vapor amount is detected, and switches back to optimum fuel efficiency when the vapor amount decreases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine operates at an optimum fuel efficiency operating point, then fuel economy is improved, but the purging speed of fuel vapor becomes slow
Solution Approach 1:
The engine operating point is made dynamic by switching between the optimum fuel efficiency operating point and the high negative pressure operating point based on the detected fuel vapor amount. When fuel vapor amount is large, the system switches to high negative pressure mode for rapid purging; when fuel vapor amount is small, it returns to optimum fuel efficiency mode, creating a dynamic adaptation to varying conditions.
Solution Approach 2:
The system changes the engine operating parameters (rotational speed and torque) based on the fuel vapor amount detected by the detector. By adjusting these parameters to create higher negative pressure in the intake manifold, the system increases the purging speed without permanently sacrificing fuel economy, as the parameter change is conditional and reversible.
2Productivity
If the engine operates at higher rotational speed with smaller torque to increase intake manifold negative pressure, then purging speed is improved, but fuel economy deteriorates
Solution Approach 1:
The system applies partial action by using the high rotational speed, small torque operating condition only partially - specifically when fuel vapor purging is required and the detected vapor amount is large. When purging is not needed or vapor amount is small, the system returns to the efficient operating point, thus applying the excessive action (higher speed, lower efficiency) only when necessary rather than continuously.
Solution Approach 2:
The engine operates periodically between two states: the optimum fuel efficiency operating point for normal operation, and the high negative pressure operating point when purging is required. This periodic switching based on detected fuel vapor amounts allows the system to maintain good fuel economy overall while periodically achieving rapid purging when needed.
3Productivity
If the purge control valve is fully opened to increase purge gas flow, then purging speed is improved, but fuel economy deteriorates when intake manifold negative pressure is low
Solution Approach 1:
The system takes preliminary action by first detecting the fuel vapor amount before initiating purging. Based on this detection, it proactively adjusts the engine operating point to create higher negative pressure in the intake manifold before opening the purge control valve, ensuring that when purging does occur, it happens efficiently without requiring excessive valve opening that would harm fuel economy.
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 approach enables the rapid purging of fuel vapor without significantly affecting the fuel economy of the internal combustion engine, ensuring efficient vapor removal when needed while maintaining optimal fuel efficiency.
Implementation Method 1
a canister that traps fuel vapor in the fuel tank and allows the trapped fuel vapor to be purged into the intake pipe of the engine
Implementation Method 2
executes purge control for purging the fuel vapor trapped by the fuel vapor trap into the intake pipe, utilizing a negative pressure of the intake pipe
Data Source
AI summary
In a power output apparatus, when the fuel vapor concentration is high and the target purge rate is high, an operating point on a purge priority operating line is selected as a target operating point of an engine. As a result, the intake manifold negative pressure greater than that when an operating point on an optimum fuel efficiency operating line is selected, so that the flow rate of purge gas released from a canister is increased. When the fuel vapor concentration does not fall within a high-concentration range, the necessity to immediately purge fuel vapor trapped in the canister into the intake pipe is low, and thus an operating point on the optimum fuel efficiency operating line is selected to keep the engine operating at high fuel efficiency.