Variable Displacement Engine Fuel Injection Transient Control
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Solution Overview
Problem
Variable displacement engines face challenges during transitions between VDE and non-VDE modes, including transient fuel control issues, emissions, and drivability problems due to incomplete combustion and trapped air charges with unburned fuel, which affect catalyst performance.
Innovation Solution
The method involves adjusting fuel injection ratios by decreasing port injector fuel and increasing direct injector fuel before deactivating cylinders, ensuring complete fuel puddle depletion, and reversing this ratio upon reactivation to establish stable combustion and minimize unburned fuel traces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If cylinders are deactivated in VDE mode to improve fuel economy, then fuel consumption is reduced, but transient fuel control issues and emissions problems occur during mode transitions
Solution Approach 1:
The patent applies preliminary action by depleting the fuel puddle in the intake port before cylinder deactivation. The controller adjusts fuel injection to consume the accumulated fuel in the intake port prior to deactivating the cylinder, ensuring that when the cylinder is reactivated, there is minimal unburned fuel to cause emissions problems. This preliminary fuel puddle depletion resolves the contradiction between fuel economy benefits of deactivation and emissions problems during transition.
2Device complexity
If port fuel injection is used to fuel deactivated cylinders, then fuel delivery is simplified, but fuel puddle accumulation causes combustion instability and emissions upon reactivation
Solution Approach 1:
The controller performs preliminary fuel puddle depletion by adjusting port injector fuel injection before deactivation. This ensures that when the cylinder is reactivated, the intake port fuel puddle is minimized, preventing combustion instability and ensuring reliable combustion upon reactivation while maintaining the simplicity of the port fuel injection system.
Solution Approach 2:
The patent changes the fuel injection parameters by adjusting the fuel injection amount and timing of the port injector before deactivation. The controller modifies these parameters to deplete the fuel puddle at the intake port, transforming the fuel delivery characteristics to prevent accumulation issues upon reactivation while maintaining system simplicity.
3Use of energy by moving object
If fuel puddle is trapped in deactivated cylinders, then fuel economy is improved, but unburned fuel in exhaust elevates catalyst temperature and degrades catalyst performance
Solution Approach 1:
The controller performs preliminary fuel puddle depletion before cylinder deactivation, ensuring that minimal unburned fuel is trapped in the cylinder. This prevents unburned fuel from entering the exhaust system and elevating catalyst temperature, thereby protecting catalyst performance while maintaining fuel economy benefits of cylinder deactivation.
Data Source
AI summary
Various systems and methods are described for controlling fuel injection in a variable displacement engine. One method for a deactivatable cylinder comprises, before deactivating the cylinder responsive to operating conditions, disabling a port injector and fueling the cylinder only via the direct injector. The method further comprises, when reactivating the cylinder from deactivation, enabling both the port injector and the direct injector, and injecting a higher amount of fuel via the direct injector while simultaneously injecting a lower amount of fuel via the port injector.