Engine Control Device Using Middle Injection to Cancel Pressure Waves
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Solution Overview
Problem
Existing engine control systems fail to fully reduce combustion noise despite attempting to offset pressure waves from pre-injection and main injection, as the different combustion modes of premix and diffuse combustion result in non-canceling frequency components of pressure waves.
Innovation Solution
A control device and method that includes a fuel injection valve performing a pre-injection, a main injection, and a middle injection, with the middle injection occurring between the pre-injection and main injection, reducing the injection amounts of the pre-injection and main injection, and optimizing injection timings to cancel pressure waves and maintain thermal efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If pre-injection and main injection are performed with half-cycle offset to cancel pressure waves, then combustion noise is reduced, but the different combustion modes (premix and diffuse) result in frequency components that cannot fully cancel
Solution Approach 1:
The patent segments the fuel injection into three distinct phases: pre-injection, middle injection, and main injection. The pre-injection and main injection are timed to produce pressure waves with half-cycle offset for cancellation, while the middle injection is inserted between them to provide additional fuel without disrupting the cancellation effect. This segmentation allows the system to maintain the pressure wave cancellation benefit while adding flexibility in fuel delivery timing and amount.
2Object-affected harmful factors
If fuel injection amount is reduced in pre-injection and main injection, then peak heat release rates are reduced and combustion noise is reduced, but total fuel injection amount must still be secured
Solution Approach 1:
The middle injection is performed as a preliminary action between the pre-injection and main injection. By delivering a portion of the required fuel amount during this intermediate phase, the system reduces the peak injection rates needed for pre-injection and main injection, thereby lowering peak heat release rates and combustion noise, while still ensuring the total fuel amount is sufficient for the combustion cycle.
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 combustion noise by canceling pressure wave peaks while maintaining engine torque and thermal efficiency, as the middle injection fills the heat release rate valleys and completes combustion before the main injection, ensuring the cancelation effect is not compromised.
Implementation Method 1
fuel injection timings and fuel injection periods of both injections are set so that pressure waves resulting from combustions by both the injections are offset by the half cycle
Implementation Method 2
combustion by the pre-injection (premix combustion) and the combustion by the main injection (diffuse combustion)
Implementation Method 3
the combustion by the middle injection serves to fill the valley between the peaks of the heat release rates by the combustions of the pre-injection and the main injection and contributes to the engine torque
Data Source
AI summary
An engine control device is provided. A fuel injection valve performs a pre-injection and a main injection on a retarding side of the pre-injection so that pressure waves resulting from combustions caused by the injections cancel each other out. The control device secures a fuel injection amount to be supplied to a combustion chamber in one cycle by at least the pre-injection, the main injection, and a middle injection. The control device causes the fuel injection valve to perform the pre-injection at a timing when a piston is located at an advancing side of compression top dead center for premix combustion, to start the main injection during a combustion period of the fuel injected by the pre-injection for diffuse combustion, and to perform the middle injection at a timing between the other two injections with a fuel injection amount less than the other injections.