Hybrid Vehicle Fuel Pressure Stabilization During Intermittent Engine Restart
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Solution Overview
Problem
In hybrid vehicles with intermittent internal combustion engine operation, the frequent stopping and restarting lead to fluctuations in fuel pressure, causing delays in catalyst rapid warm-up and potential air-fuel ratio variations, which adversely affect exhaust gas purification performance.
Innovation Solution
A control apparatus that restarts the internal combustion engine using only port injection until the fuel pressure for in-cylinder injection reaches a preset reference set pressure, then initiates in-cylinder injection to maintain stable air-fuel ratio and ensure catalyst rapid warm-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the internal combustion engine is intermittently operated to reduce fuel consumption, then fuel efficiency is improved, but high-pressure side fuel pressure is reduced due to frequent stopping and restarting
Solution Approach 1:
The control device performs preliminary action by determining whether the engine is restarted after temporary stop and, if so, controlling the in-cylinder injection to be stopped until the fuel pressure reaches a predetermined value. This preliminary control prevents air-fuel ratio variations that would occur due to delayed fuel pressure buildup after intermittent stopping, thereby resolving the contradiction between fuel efficiency improvement and fuel pressure maintenance.
2Use of energy by moving object
If the in-cylinder injection is used to improve fuel efficiency and exhaust gas purification, then fuel efficiency is improved, but air-fuel ratio variation occurs when fuel pressure increases are delayed
Solution Approach 1:
The control device employs feedback by monitoring the fuel pressure level and the operational state of the engine (whether restarted after temporary stop). Based on this feedback, the control device adjusts the in-cylinder injection timing - specifically stopping the injection until fuel pressure reaches a predetermined value after restart. This feedback-based control ensures stable air-fuel ratio while maintaining the fuel efficiency benefits of in-cylinder injection.
3Object-generated harmful factors
If the catalyst rapid warm-up is performed by retarding ignition timing, then exhaust gas purification is improved, but the process is adversely affected by air-fuel ratio variations
Solution Approach 1:
The control device performs preliminary action by pre-determining the fuel pressure status before initiating catalyst rapid warm-up. When the engine is restarted after temporary stop, the control device stops in-cylinder injection until fuel pressure reaches the predetermined value, ensuring that the subsequent catalyst rapid warm-up process occurs with stable air-fuel ratio. This preliminary control prevents air-fuel ratio variations from adversely affecting the catalyst warm-up, thereby ensuring reliable exhaust gas purification.
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 prevents air-fuel ratio variations and ensures reliable catalyst rapid warm-up, securing the required exhaust gas purification performance by maintaining stable fuel pressure and injection control.
Implementation Method 1
the combustion in the cylinder is retarded to such a degree that the combustion is performed in the exhaust stroke by significantly retarding ignition timing. Thus, by retarding the combustion in the cylinder, an exhaust temperature is increased and a catalytic converter for exhaust gas purification is rapidly warmed up
Implementation Method 2
a low-pressure fuel pump in the fuel supply system is driven by the motor. By driving the low-pressure fuel pump, a fuel pressure level higher than the vapor pressure level of the fuel is secured and the occurrence of the fuel vapor is thereby reduced
Data Source
AI summary
An intermittent operation control is executed, wherein a hybrid vehicle is run with a running drive source while an internal combustion engine is intermittently operated in the intermittent operation control. When the internal combustion engine is restarted after a stop due to the intermittent operation control, a rapid warm-up control is executed in which a catalytic converter is rapidly warmed up by retarding the ignition timing of the internal combustion engine. In addition, when the internal combustion engine is restarted, the internal combustion engine is operated only by port injection until the pressure of fuel for in-cylinder injection reaches a reference set pressure. Subsequently, when the pressure of the fuel for in-cylinder injection reaches the reference set pressure, the in-cylinder injection is started.