Forward Air Intake Port for Outboard Engine
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Solution Overview
Problem
The existing air intake structures in outboard motors, with intake ports located rearward of the engine cover, face challenges such as intake resistance, reduced air intake efficiency, and decreased combustion efficiency due to air being drawn against the flow of external air, leading to poor engine power and fuel economy.
Innovation Solution
The air intake structure is redesigned with an air intake port that opens forward, featuring a louver and a bulging portion on the engine cover to convert dynamic pressure into static pressure, along with a separator for gas/liquid separation and a drain passage with a backflow prevention mechanism to prevent water intrusion, ensuring efficient air intake and charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the air intake port is provided rearward of the engine cover, then the structure is simple and compact, but air intake efficiency deteriorates due to negative pressure resistance from air flow direction
Solution Approach 1:
The air intake port is inverted from the conventional rearward opening to a forward opening configuration. This allows the air intake direction to align with the forward motion of the outboard motor, eliminating negative pressure resistance and improving air intake efficiency while maintaining structural simplicity
2Productivity
If the air intake port opens forward, then air intake efficiency improves by aligning with air flow, but water intrusion risk increases
Solution Approach 1:
A lid member is introduced as an intermediary component between the forward-opening air intake port and the internal space. This lid member selectively controls air intake while preventing water intrusion, allowing the system to maintain high air intake efficiency without the harmful effect of water entering the throttle body
Solution Approach 2:
The lid member is configured to be movable, enabling dynamic adjustment of the air intake port opening. This allows the system to optimize air intake during operation while closing or restricting the opening during conditions that could cause water intrusion, thus adapting to changing operational environments
3Device complexity
If air flows through space near the engine, then the structure is compact, but charging efficiency deteriorates due to air heating
Solution Approach 1:
The internal space is segmented into distinct regions: an air intake passage for cool air flow and an engine housing space. This segmentation allows the air intake path to be separated from the engine, preventing air heating while maintaining structural compactness through optimized spatial arrangement
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 configuration enhances air intake efficiency, improves combustion efficiency, and prevents water intrusion into the throttle body, resulting in better engine performance and fuel economy.
Implementation Method 1
an expansion chamber is provided inside the engine cover with an inner space formed by the bulging portion, and the expansion chamber configured to convert dynamic pressure of the air taken in through the air intake port into static pressure
Implementation Method 2
a separator for gas/liquid separation and a drain passage with a backflow prevention mechanism to prevent water intrusion
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
In an air intake structure for an outboard motor, in which air is taken in through an air intake port formed in an engine cover covering upper portion of the outboard motor and the air is delivered to a throttle body in order for the air to be drawn into the throttle body, the air intake structure is characterized in that the engine cover is provided with an air intake port opened forward in an advancing direction of an outboard motor and a lid member configured to open and close the air intake port, and a space configured to communicate the air intake port and the throttle body with each other is provided so as to be isolated from an engine room.