Engine Controller Water Injection Timing for Intake Passage Humidity
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Solution Overview
Problem
Existing technologies for water injection in internal combustion engines face challenges due to water collecting on the wall surface of the intake passage, leading to increased temperature and reduced relative humidity, which can result in insufficient water supply to the cylinders.
Innovation Solution
A controller for an internal combustion engine that calculates a water collection amount based on intake air temperature and injects water during both the open and closed periods of the intake valve, with additional injections when the calculated water collection amount is less than a specified value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If water injection valves inject water into the intake passage, then the temperature in the cylinders is lowered through evaporation, but the water collects on the wall surface of the intake passage forming a film, which increases the temperature of the intake passage and reduces relative humidity, causing water to evaporate before reaching the cylinders
Solution Approach 1:
The controller performs a water collection amount calculation process before the injection process to predict how much water will collect on the intake passage wall surface. Based on this prediction and the detected intake air temperature, the controller determines the appropriate injection amount in advance, preventing water loss from evaporation before water is needed in the cylinders.
Solution Approach 2:
The controller uses the detected intake air temperature as feedback to adjust the water injection strategy. When the intake air temperature is high, the controller increases the water injection amount during the valve closed period to compensate for expected evaporation losses, ensuring sufficient water reaches the cylinders regardless of evaporation conditions in the intake passage.
2Productivity
If water is injected only when the intake valve is open, then the water can reach the cylinders efficiently, but in high temperature conditions the water evaporates in the intake passage before reaching the cylinders, resulting in insufficient water supply
Solution Approach 1:
The water injection process is segmented into two distinct phases: injection during the valve open period for efficient delivery, and additional injection during the valve closed period when water collection amount is insufficient. This segmentation allows the system to optimize for both delivery efficiency and sufficient water quantity reaching the cylinders under different operating conditions.
Solution Approach 2:
The controller changes the injection timing parameter based on the water collection amount calculation and intake air temperature detection. When the calculated water collection amount is less than the required amount, the controller activates additional injection during the valve closed period, changing the temporal parameter of water injection to ensure sufficient water reaches the cylinders despite evaporation in the intake passage.
3Loss of substance
If the water collection amount on the intake passage wall surface is small, then less water evaporates from the wall surface, but the temperature of the intake passage increases and relative humidity decreases, making the intake passage environment drier and promoting evaporation of injected water
Solution Approach 1:
The controller calculates the water collection amount before injection and, when it is insufficient, performs additional water injection during the valve closed period. This preliminary action ensures that enough water is present on the intake passage wall surface to maintain adequate humidity levels and prevent excessive evaporation of the water intended for cylinder delivery.
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 solution ensures a consistent and sufficient water supply to the cylinders, preventing water from evaporating in the intake passage and maintaining optimal humidity levels.
Implementation Method 1
the water collects on the wall surface of the intake passage in the form of a film
Implementation Method 2
the water evaporates from the wall surface... the heat of vaporization lowers the temperatures
Implementation Method 3
the heat of vaporization lowers the temperatures in the cylinders
Implementation Method 4
the water in the intake passage readily evaporates before reaching the inside of the cylinders
Data Source
Figure 1~2(d)
Figure 3
Figure 4
AI summary
A controller for an internal combustion engine is configured to calculate a water collection amount based on a temperature of intake air flowing through an intake passage, the water collection amount being an amount of water that collects on a wall surface of the intake passage, cause a water injection valve to inject water to the intake passage when an intake valve is open, and cause the water injection valve to inject water when the intake valve is closed in addition to when the intake valve is open in a case in which the water collection amount is less than a specified value that has been defined in advance.