Direct Fuel Injection for Cylinder Reactivation
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Solution Overview
Problem
Existing engine systems face delays in cylinder reactivation due to the need for end-of-injection fuel to precede intake valve closure, leading to delayed engine torque production and reduced vehicle drivability.
Innovation Solution
Direct fuel injection into a cylinder after deactivation allows for quicker reactivation by initiating combustion during the compression stroke, even with closed intake valves, and subsequent port injection for subsequent combustion events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If port fuel injection is used to reactivate cylinders, then fuel is injected before intake valve closing, but cylinder reactivation delay occurs and engine torque production is delayed
Solution Approach 1:
The system performs preliminary fuel injection into the cylinder before the intake valve closes during the reactivation process. By injecting fuel during the compression stroke before intake valve closure, the fuel is already present in the cylinder when combustion is initiated, eliminating the delay associated with waiting for intake valve closing. This preliminary action of fuel injection resolves the contradiction by ensuring fuel is in position before the timing constraint occurs.
Solution Approach 2:
The system inverts the conventional fuel injection sequence by injecting fuel after intake valve closure rather than before. This reversal allows the intake valve to close first, trapping the fuel already present in the cylinder, and then combustion is initiated. This inversion of the injection timing relative to valve closure eliminates the reactivation delay while maintaining proper air-fuel mixture formation.
2Speed
If direct fuel injection is used during compression stroke, then combustion can start with closed intake valves, but requires coordination of injection timing with valve events
Solution Approach 1:
The control system uses feedback from crankshaft position sensors and valve timing sensors to dynamically adjust the direct injection timing. By continuously monitoring the actual position of the crankshaft and the timing of valve events, the system can precisely coordinate fuel injection with the compression stroke even as operating conditions change. This feedback mechanism enables rapid reactivation while managing the complexity through adaptive control rather than fixed timing.
Solution Approach 2:
The fuel injection system is designed to perform multiple functions: it can inject fuel during the intake stroke for normal operation, during the compression stroke for rapid reactivation, and can adjust injection duration and quantity based on cylinder state. This multi-functionality allows the same injection system to handle both rapid reactivation and normal fuel delivery, reducing overall system complexity while achieving fast reactivation when needed.
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 reduces cylinder reactivation delay, improves engine air-fuel control, and enhances vehicle drivability by enabling quicker torque production after cylinder reactivation.
Implementation Method 1
directly injecting fuel to a cylinder for a first combustion event in the cylinder after the cylinder is deactivated
Implementation Method 2
port injecting fuel to the cylinder a first time after the cylinder is deactivated for a second combustion event
Implementation Method 3
combustion ceases in the deactivated cylinders as fuel flow ceases to the deactivated cylinders
Data Source
AI summary
Systems and methods for operating an engine with deactivating and non-deactivating valves are presented. In one example, fuel supplied to cylinders being reactivated is supplied by direct fuel injectors even though the engine is operating in a region (e.g., speed and torque) where under conditions where cylinders are not being reactivated the engine injects fuel solely via port fuel injectors.