Engine Speed Fluctuation Correction via Ignition Timing
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Solution Overview
Problem
During a cold start, internal combustion engines experience engine speed fluctuations and high hydrocarbon emissions due to the oxygen sensor's initial inability to provide accurate feedback and the catalytic converter's inefficiency at low temperatures, leading to inadequate control over fuel injection and ignition timing.
Innovation Solution
The ignition timing is dynamically adjusted based on the roughness of engine operation by comparing it to a threshold limit, allowing for discrete changes in ignition timing and fuel delivery for individual combustion events to maintain engine stability and reduce emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional fuel injection and ignition timing control are used during cold start, then the engine can operate without feedback control, but hydrocarbon emissions increase and engine speed fluctuates
Solution Approach 1:
The patent implements feedback control using engine speed measurements from a crankshaft position sensor. The ECU continuously monitors engine speed and compares it to a target value, then adjusts ignition timing based on the speed deviation to maintain stable operation and reduce emissions during cold start conditions
2Stability of the object's composition
If ignition timing is adjusted to reduce engine roughness, then engine speed stability improves, but control complexity increases
Solution Approach 1:
The system uses the engine's own speed fluctuations as the control signal. The ECU measures actual engine speed, compares it to the target speed, and automatically adjusts ignition timing without requiring external intervention or complex control algorithms, making the system self-regulating and relatively simple
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 effectively reduces hydrocarbon emissions during initial engine operation after a cold start by maintaining low engine roughness and improving engine performance without relying on immediate oxygen sensor feedback, allowing for transition to closed-loop control once the sensor warms up.
Implementation Method 1
a crankshaft position sensor that produces a signal having a frequency proportional to engine speed
Implementation Method 2
a spark plug ignites the fuel and air in the combustion chamber
Implementation Method 3
a fuel injector discharges fuel into air in an intake manifold or combustion chamber of the engine
Implementation Method 4
An oxygen sensor generally disposed upstream of an exhaust system and capable of sensing the oxygen level in the exhaust gas emitted from the engine
Data Source
AI summary
Ignition timing for a combustion engine may be controlled by determining the roughness of current engine operation, comparing the determined roughness with a control roughness to determine if the determined roughness is within a threshold limit of the control roughness, and changing the ignition timing in a subsequent fuel delivery event as a function of the difference between the determined roughness and the control roughness. Preferably, the ignition timing is changed at least when the determined roughness is not within the threshold limit, although other factors may be taken into account when changing the ignition timing.