Butterfly Throttle Valve Through Hole Prevents Carbon Deposition
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Solution Overview
Problem
In outboard motors with internal combustion engines and carburetors, the deposition of solid matters in the gap between the throttle valve and the side wall of the intake passage leads to reduced engine speed stability and frequent maintenance needs, especially during idling and light-load operations.
Innovation Solution
The design incorporates a butterfly-type throttle valve with a second valve part featuring a through hole that allows exhaust gases containing foreign matters to flow through, preventing deposition by directing them away from the intake passage gap, while maintaining fuel discharge efficiency through bypass ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the throttle valve is designed to control air intake in a conventional manner, then air flow control is achieved, but solid matter deposition occurs in the gap between the throttle valve and side wall
Solution Approach 1:
The patent extracts the harmful exhaust gas flow path from the gap between the throttle valve and side wall by introducing a through-hole in the second valve part. This allows exhaust gas to be directed through the through-hole rather than depositing in the gap, thereby eliminating the harmful deposition effect while maintaining the throttle valve's air control function.
Solution Approach 2:
The through-hole acts as an intermediary structure that mediates between the exhaust gas flow and the throttle valve gap. It provides an alternative pathway for exhaust gas to pass through the valve assembly without contacting the gap surface, thus preventing deposition while allowing controlled air flow through the first valve part edge.
2Loss of energy
If the throttle valve is fully closed during idling, then fuel economy is improved, but exhaust gas spat back deposits solid matter in the intake passage gap
Solution Approach 1:
The through-hole in the second valve part extracts the exhaust gas flow path from the gap region. Even when the throttle valve is fully closed during idling, exhaust gas that spills back through the bypass ports is directed through the through-hole rather than depositing in the gap, allowing full closure to maintain fuel economy without the harmful deposition effect.
3Reliability
If maintenance is performed frequently to prevent unstable operation, then operation stability is maintained, but maintenance time and cost increase
Solution Approach 1:
By extracting the exhaust gas flow path through the through-hole, the patent eliminates the primary cause of solid matter deposition that leads to unstable operation. This prevents the accumulation of deposits that would require frequent maintenance, thereby extending maintenance intervals while maintaining operation stability.
Solution Approach 2:
The through-hole structure provides preliminary protection against solid matter deposition by directing exhaust gas away from the gap before deposition can occur. This preventive design eliminates the need for frequent maintenance interventions, extending the time between maintenance requirements.
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 solution effectively prevents solid matter deposition, stabilizes idling and light-load operations, and significantly extends the maintenance interval of the internal combustion engine.
Implementation Method 1
the second valve part is provided with a through hole that allows air to flow therethrough at a flow rate necessary for idling when the throttle valve is at the fully closed position
Implementation Method 2
negative pressure will not directly act through the through hole on the bypass ports and hence fuel discharge through the bypass ports is affected scarcely by the through hole
Data Source
AI summary
An outboard motor has an internal combustion engine with a carburetor. The carburetor is designed to extend maintenance interval greatly by preventing or suppressing the deposition of solid matters in the gap between the intake passage and a butterfly-type throttle valve therein. The throttle valve is divided, by a valve axis about which the throttle valve turns, into a first valve part that turns from the downstream side to the upstream side with respect to an air intake direction when the fully closed throttle valve is opened and a second valve part that turns from the upstream side to the downstream side with respect to the air intake direction when the fully closed throttle valve is opened. The first valve part has an edge that moves to the upstream side past bypass ports when the fully closed throttle valve is opened, and the second valve part is provided with a through hole that allows air to flow therethrough at a flow rate necessary for idling when the throttle valve is fully closed.