Outboard Engine Intake Path Switching for Water Drainage
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Solution Overview
Problem
Conventional outboard engines face issues with water ingress during low-load low-speed operations, leading to combustion failure, output reduction, and component damage or corrosion when covered with water.
Innovation Solution
An outboard engine design featuring an outside air introduction port, a throttle body, an intake air guide portion with a switching valve and actuator, and a control device that selects between a long drainage path and a short path in the intake air guide portion, preventing water entry by switching to the long path when the engine is stopped or expected to be covered with water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If an on-off valve is provided at an upstream side of the second intake port to control fuel vaporization, then combustion stability during low-load low-speed operation is improved, but water enters the engine through the open valve when the outboard engine is covered with water
Solution Approach 1:
The intake air guide portion is divided into multiple paths (first intake passage and second intake passage) with different characteristics. The first path provides water drainage effect while the second path provides direct air intake. This segmentation allows the system to select the appropriate path based on operating conditions, preventing water entry while maintaining combustion stability.
Solution Approach 2:
The switching valve dynamically changes the air intake path based on engine operating conditions. When the engine is stopped or operating in conditions where water coverage is expected, the valve switches to the first intake passage with drainage effect. During normal operation, it switches to the second intake passage for direct air intake, thus adaptively preventing water entry while maintaining combustion performance.
2Use of energy by moving object
If the on-off valve is switched in response to engine operation range, then fuel vaporization is controlled, but combustion failure and output reduction occur when water enters the engine
Solution Approach 1:
The system performs preliminary action by switching to the first intake passage with drainage effect before water can enter the engine. The control device detects conditions where water coverage is expected (such as when the engine is stopped or during low-speed operation) and proactively switches the intake path, preventing water entry before it can cause combustion failure or damage components.
Solution Approach 2:
The first intake passage acts as an intermediary path that provides both air intake and water drainage functionality. This intermediate path with drainage effect serves as a buffer between the external environment and the engine, allowing water to be drained away before it can reach the combustion chamber, thus protecting combustion reliability.
3Productivity
If the engine operates in a short path without drainage effect, then air intake efficiency is improved, but water enters the engine causing component damage and corrosion
Solution Approach 1:
The system dynamically switches between the short path (second intake passage) for high air intake efficiency during normal operation and the long path (first intake passage) with drainage effect when water coverage is expected. This dynamic adaptation allows the system to maximize air intake efficiency while preventing water damage through timely path switching.
Solution Approach 2:
The control device changes the operating parameter (intake air path) based on detected conditions. When the engine is stopped or operating in conditions where water coverage is expected, the parameter changes from the short path to the long path with drainage effect, thus preventing water entry while maintaining the ability to use the efficient short path during normal operation.
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
This design secures engine performance and prevents malfunction of components even when the engine is covered with water, ensuring durability and preventing damage or corrosion by effectively draining water from the intake system.
Implementation Method 1
a path of the intake air guide portion is made switchable to a long path including a drainage effect to water entering the intake air guide portion
Data Source
AI summary
In an outboard engine including a throttle body that feeds combustion air that is taken in from an outside air introduction port, into an engine body, an intake duct that guides the combustion air from the outside air introduction port, and an on-off valve disposed partway in the intake duct, a plurality of paths are provided in the intake duct, a path of the intake duct is made switchable to a long path including a drainage effect to water entering the intake duct and a short path that does not include the drainage effect by the on-off valve, and the long path is selected at a time of an engine being stopped or a time of an operation state where the outboard engine is expected to be covered with water.