Engine Controller Backflow Rate Calculation for Gaseous Fuel Injection Valves
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Solution Overview
Problem
In internal combustion engines using gaseous fuels like CNG, abnormal combustion such as pre-ignition can lead to excessively high in-cylinder pressures, causing combustion gas to flow back into the direct injection valve, potentially damaging it due to temperature differences.
Innovation Solution
A controller is implemented to calculate a backflow rate of combustion gas into the direct injection valve based on in-cylinder pressure and supply fuel pressure, with the backflow rate increasing as in-cylinder pressure rises and supply fuel pressure decreases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If supply fuel pressure is reduced to prevent pre-ignition, then abnormal combustion is suppressed, but combustion gas backflow into the direct injection valve increases
Solution Approach 1:
The controller calculates the backflow rate based on detected in-cylinder pressure and supply fuel pressure, then uses this calculated value as feedback to control the fuel injection amount, creating a closed-loop control system that dynamically adjusts injection to compensate for backflow effects
Solution Approach 2:
The patent replaces direct mechanical pressure control with a calculation-based control system that uses pressure sensors and computational algorithms to determine optimal fuel injection amounts, substituting physical pressure regulation with intelligent control logic
2Object-affected harmful factors
If direct injection valve is kept closed to prevent backflow, then combustion gas flow back is reduced, but fuel injection capability is compromised
Solution Approach 1:
The control system dynamically adjusts the fuel injection amount based on real-time calculation of backflow rate, allowing the injection valve to operate optimally under varying conditions rather than remaining statically closed, thus maintaining both protection and functionality
3Productivity
If in-cylinder pressure is allowed to rise during compression, then combustion efficiency improves, but direct injection valve closure becomes difficult
Solution Approach 1:
The controller calculates the backflow rate in advance based on predicted in-cylinder pressure and supply fuel pressure conditions, and pre-adjusts the fuel injection amount to compensate for expected backflow, preventing valve instability before it occurs
Solution Approach 2:
The system changes the fuel injection amount parameter dynamically based on calculated backflow rate, adjusting this critical parameter to maintain valve closure stability while allowing in-cylinder pressure to reach optimal combustion levels
Data Source
AI summary
A controller is used for an internal combustion engine including a cylinder and a direct injection valve that injects gaseous fuel into the cylinder. A CPU of the controller executes acquisition of an in-cylinder pressure that is a pressure in the cylinder during one combustion cycle and a supply fuel pressure that is a pressure of the gaseous fuel supplied to the direct injection valve, and calculation of a backflow rate that is an amount of combustion gas flowing into the direct injection valve from the cylinder during one combustion cycle of the cylinder. In the calculation of the backflow rate, the CPU calculates the backflow rate such that the backflow rate becomes larger as the in-cylinder pressure increases and the backflow rate becomes larger as the supply fuel pressure decreases.