Watercraft Propulsion System Lean-Burn Control with Supercharging
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Solution Overview
Problem
Current watercraft propulsion systems do not integrate a supercharging device with lean-burn engine control for improved fuel efficiency and higher output power, as described in existing patents.
Innovation Solution
A watercraft propulsion system incorporating a supercharging device and an engine capable of lean-burn operation, where a controller computes and adjusts fuel injection based on engine rotation speed and air intake pressure to maintain an air/fuel ratio within a lean-burn range, enhancing fuel efficiency and output power without the need for exhaust gas cleaning catalysts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a supercharging device is added to increase output power, then the device complexity and cost increase
Solution Approach 1:
The patent combines the supercharging device with the exhaust system by routing exhaust gases through a turbine that drives the supercharger compressor. This integration allows the exhaust energy to be utilized for forcing fresh air into the combustion chamber, achieving higher output power while maintaining system compactness and reducing overall complexity.
2Use of energy by moving object
If lean-burn control is implemented to improve fuel efficiency, then the combustion stability may deteriorate
Solution Approach 1:
The patent implements lean-burn control by adjusting the air/fuel ratio parameter to exceed the stoichiometric ratio (λ>1), typically in the range of 1.05-1.3. This parameter change improves fuel efficiency by reducing fuel consumption per unit power. Combined with supercharging that maintains adequate cylinder filling, the system achieves stable combustion despite the lean mixture.
Solution Approach 2:
The patent employs feedback control through oxygen sensors (lambda sensors) in the exhaust system that monitor the air/fuel ratio and provide signals to the ECU. The ECU adjusts fuel injection quantities based on this feedback to maintain the target lean air/fuel ratio, ensuring both fuel efficiency and combustion stability through continuous closed-loop control.
3Object-generated harmful factors
If exhaust gas cleaning catalysts are added to reduce pollutant emissions, then the device complexity and cost increase
Solution Approach 1:
The patent converts the harmful exhaust gases into a beneficial resource by routing them through a turbine that drives the supercharger. The exhaust energy, which would otherwise be wasted heat, is transformed into mechanical work to compress intake air, eliminating the need for separate exhaust treatment systems and reducing overall device complexity.
Solution Approach 2:
The system achieves self-service by using its own exhaust gases to power the supercharger turbine, which in turn forces more air into the combustion chamber. This internal recycling of exhaust energy improves fuel efficiency and reduces emissions without requiring external catalysts or additional complex emission control systems.
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 system achieves improved fuel efficiency and higher output power by maintaining an air/fuel ratio between 15 and 25, reducing pollutant concentrations in exhaust gases, and eliminating the need for catalysts, while maintaining stable combustion.
Implementation Method 1
a supercharging device provided in the air intake channel
Implementation Method 2
a fuel injector... to drive the fuel injector based on the computed command fuel injection amount
Implementation Method 3
the controller is configured or programmed to compute a command fuel injection amount so that the engine performs a combustion operation at an air/fuel ratio in a lean-burn range
Data Source
AI summary
A watercraft propulsion system includes a propulsion unit to be driven by an engine. The engine includes a cylinder block, an air intake channel, an exhaust channel, a supercharging device, and a fuel injector. The watercraft propulsion system includes the engine, the propulsion unit to be driven by the engine, a rotation speed sensor to detect a rotation speed of the engine, an air intake pressure sensor to detect an air intake pressure of the engine, and a controller. The controller is configured or programmed to compute a command fuel injection amount so that the engine performs a combustion operation at an air/fuel ratio in a lean-burn range (lean-combustion range) according to the rotation speed detected by the rotation speed sensor and the air intake pressure detected by the air intake pressure sensor, and to drive the fuel injector based on the computed command fuel injection amount.