Marine Dual-Fuel Engine Intake Valve Timing for Knock-Free Power-Up
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Solution Overview
Problem
Existing fuel gas engines face issues with turbochargers failing to keep up with increased fuel gas feed rates, leading to knocking and prolonged power-up times, while also needing to meet stringent emission regulations.
Innovation Solution
Implementing a variable intake valve timing (VIVT) mechanism to adjust the intake valve closing timing, coupled with a turbocharger and air cooler, to lower the compression ratio and suppress knocking, thereby shortening power-up times and improving fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors are arranged in the exhaust passage to detect various components, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple detection functions into a single sensor unit. The ionization-type sensor integrates detection capabilities for multiple exhaust components (hydrocarbons, carbon monoxide, oxygen, and temperature) into one device, avoiding the need for separate sensors for each parameter while maintaining detection accuracy.
Solution Approach 2:
The ionization-type sensor serves multiple detection purposes simultaneously. It can detect hydrocarbon concentrations, carbon monoxide levels, oxygen content, and exhaust temperature using a single sensor element, making it a universal detection device for exhaust gas analysis.
2Loss of energy
If air is supplied to the exhaust passage to promote oxidation, then oxidation efficiency is improved, but energy loss increases
Solution Approach 1:
The patent introduces air in a controlled, partial manner rather than excessive amounts. The air supply is regulated to provide just enough oxygen for the desired oxidation reactions occurring in the exhaust passage, avoiding unnecessary energy consumption from overheating or excessive air injection while still achieving effective oxidation of harmful components.
Solution Approach 2:
The air supply mechanism operates continuously or in sustained intervals to maintain oxidation conditions throughout the exhaust passage. This continuous action ensures that oxidation of hydrocarbons and carbon monoxide occurs consistently without interruption, maximizing productivity while controlling energy input.
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 VIVT mechanism effectively suppresses knocking and reduces power-up times by optimizing intake valve timing, while meeting emission standards and maintaining fuel efficiency.
Implementation Method 1
an ionization-type sensor that detects a concentration of hydrocarbons in the exhaust based on a degree of ionization of the hydrocarbons
Implementation Method 2
a control device supplies air into an exhaust passage to promote oxidation of the hydrocarbons and the carbon monoxide
Data Source
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AI summary
A fuel-air mixture of a fuel gas and air is combusted in a combustion chamber in a gas mode of a marine dual fuel engine (1). When power of the engine (1) is increased, power is calculated by a control unit (22) from data on a rotational speed and a torque measured by a rotational speed sensor (20) and a torque sensor (21) of a crankshaft (2). Advance of an opening/closing timing of an intake valve (8) is set from a first map (24) and a second map (25) on the basis of the data on the rotational speed and the power. A second electric signal of the opening/closing timing is converted into a pressure by an electropneumatic converter (27) and adjusts a movement amount of a rod using an actuator (28). A variable intake valve timing mechanism (30) is operated on the basis of the movement amount of the rod to adjust the opening/closing timing of the intake valve (8) by advancing the opening/closing timing of the intake valve (8), and control of lowering a compression ratio of a fuel-air mixture is performed. A power-up speed can be increased while preventing knocking by setting advance amount of the opening/closing timing of the intake valve (8) using the first map and the second map in which the advance amount is previously determined.