Engine Cylinder Fuel Supply Timing for Cold Start HC Reduction
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Solution Overview
Problem
Existing methods for starting a multi-cylinder internal combustion engine at cold start-up result in high unburned hydrocarbon (HC) emissions due to excessive fuel supply, which is not adequately reduced by current cylinder-specific fuel control strategies.
Innovation Solution
A control apparatus that initially supplies fuel to only some cylinders and delays fuel supply to other cylinders, using representative temperature and engine speed calculations to optimize the timing of fuel supply to reduce unburned HC emissions, with optional features including alcohol concentration consideration and combustion count adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large amount of fuel is supplied to all cylinders at start-up to form an ignitable air-fuel mixture, then the engine can start reliably, but unburned hydrocarbon emissions increase significantly
Solution Approach 1:
The patent divides the cylinder group into two segments: cylinders that receive fuel supply from the start of operation, and cylinders that delay fuel supply until after a predetermined number of cycles. This segmentation allows the engine to start reliably using fuel from the first group while the second group remains idle, reducing total fuel consumption and unburned HC emissions during the cold start-up phase when the catalyst is not yet active.
2Object-generated harmful factors
If fuel supply is delayed to some cylinders, then unburned HC emissions are reduced, but engine vibrations are prolonged during start-up
Solution Approach 1:
The patent implements periodic fuel supply control where cylinders are cyclically activated. Specifically, fuel supply to the second group of cylinders is delayed by a predetermined number of cycles (e.g., 2-4 cycles) after engine start-up. This periodic approach allows the engine to operate initially on a subset of cylinders, reducing emissions, then gradually activates all cylinders as the engine warms up and catalyst becomes effective, thereby managing vibrations in a controlled temporal sequence.
3Object-generated harmful factors
If fuel supply pattern is based on water temperature, then cold start-up emissions are addressed, but the control system complexity increases
Solution Approach 1:
The patent utilizes water temperature as a key parameter to determine the fuel supply pattern. Based on the detected water temperature, the control system selects appropriate delayed cylinder patterns from pre-established patterns. This parameter-based approach allows the system to adapt to different thermal conditions (cold start-up vs. warm operation) without requiring complex real-time calculations, thereby managing emissions effectively while keeping the control logic relatively simple and implementable.
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
Effectively reduces unburned HC emissions during engine start-up by optimizing fuel supply timing based on engine conditions, while preventing prolonged engine vibrations and ensuring catalyst warm-up for efficient emissions control.
Implementation Method 1
a part of fuel that is injected into an intake port from a fuel injector vaporizes in the state it is in when it is injected
Implementation Method 2
the remainder adheres temporarily to a wall surface (including an intake valve) of the intake port
Implementation Method 3
The fuel that adheres to the intake port is evaporated by a negative pressure inside an intake pipe
Implementation Method 4
the action of heat from the intake port wall surface
Implementation Method 5
Although a catalyst for purifying exhaust gas is disposed in the exhaust passage, because the temperature of the catalyst is low at start-up, a certain period of time is required until the purification ability of the catalyst is activated
Data Source
AI summary
A control apparatus for an internal combustion engine that can suppress the emission of unburned HC accompanying start-up of an internal combustion engine. The control apparatus including a fuel supply control unit that initially supplies fuel to only some cylinders, and delays the start of fuel supply to delayed cylinders that are cylinders other than the aforementioned cylinders; an engine discharge gas HC amount predicting unit that calculates a relationship between a delayed cylinder starting engine speed that is a engine speed at a timing at which a cycle starts in which a delayed cylinder initially carries out combustion and a predicted value of an engine discharge gas HC amount; and a target engine speed calculating unit that calculates a target engine speed that is a target value of the delayed cylinder starting engine speed.