Engine Controller Crank Chamber Pressure Management
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Solution Overview
Problem
Existing internal combustion engine control systems do not effectively manage the pressure of gas in the crank chamber, which can become excessively high due to water collection and evaporation in the cylinders.
Innovation Solution
A controller is configured to execute a pressure calculation process to determine the crank chamber pressure based on the engine's running state, and to adjust the ratio of first and second water injection amounts depending on whether the pressure is greater than or equal to a specified value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If water is injected into the intake passage to cool the cylinders, then the temperature in the cylinders is lowered, but the pressure of gas in the crank chamber becomes excessively high
Solution Approach 1:
The controller calculates the crank chamber pressure in advance and determines the appropriate water injection amounts before injection occurs. By predicting the pressure buildup from water evaporation, the system pre-adjusts injection quantities to prevent excessive pressure while achieving desired cooling effects.
Solution Approach 2:
The system continuously monitors engine running state and calculates crank chamber pressure in real-time. Based on this feedback, the controller dynamically adjusts the water injection amounts to maintain pressure within acceptable limits while achieving cooling objectives.
2Temperature
If the amount of water injected is increased to improve cooling, then the temperature reduction effect is enhanced, but the pressure buildup in the crank chamber becomes more severe
Solution Approach 1:
The controller changes the injection parameter (amount) based on the calculated crank chamber pressure. When pressure is high, the injection amount is reduced; when pressure is low, injection can be increased to achieve better cooling. This dynamic parameter adjustment optimizes both cooling effectiveness and pressure control.
Solution Approach 2:
Instead of injecting a fixed excessive amount of water for cooling, the system applies partial injection amounts calibrated to the actual crank chamber pressure conditions. This prevents over-injection that would cause excessive pressure buildup while still achieving sufficient cooling through optimized partial doses.
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
The solution effectively prevents excessive pressure buildup in the crank chamber by adjusting water injection amounts based on real-time pressure calculations, thereby ensuring proper engine operation.
Implementation Method 1
The water injected by the water injection valves flows into the cylinders through the intake passage and evaporates in the cylinders. When the water evaporates, the heat of vaporization lowers the temperatures in the cylinders.
Implementation Method 2
When the water that has reached the inside of the cylinders may collect on the wall surfaces of the cylinders. When the piston reciprocates with the water collecting on the wall surface of each cylinder, the water may enter the crank chamber as the piston slides relative to the wall surface of the cylinder. When the water that has reached the inside of the crank chamber evaporates, the pressure of gas in the crank chamber increases.
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 3
AI summary
A controller for an internal combustion engine is configured to execute: a pressure calculation process that calculates pressure of gas in a crank chamber based on a running state of the internal combustion engine; a first injection process that causes a water injection valve to inject a first injection amount of water when an intake valve is open; and a second injection process that causes the water injection valve to inject a second injection amount of water when the intake valve is closed. The controller is further configured to set a ratio of the first injection amount to a sum of the first injection amount and the second injection amount to a smaller value when the pressure is greater than or equal to a specified value than when the pressure is less than the specified value.