Outboard Motor Engine Secondary Air System Compact Layout
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Solution Overview
Problem
Outboard motor engines face challenges in compactly arranging multiple functional devices like catalytic converters and air pumps within limited spaces, leading to size increases due to spatial constraints with neighboring components.
Innovation Solution
An engine design featuring a vertically oriented in-line multiple-cylinder engine with a secondary air supply system that includes an intake silencer, check valve, secondary air supply control valve, and passage, arranged in the side portion of the cylinder block between the crankcase and exhaust manifold, allowing for compact configuration by preventing water intrusion and optimizing space usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If accessories such as catalytic converter and air pump are arranged in addition to intake and exhaust systems within limited space of engine housing, then exhaust gas purification functionality is obtained, but device complexity and spatial arrangement difficulty increase
Solution Approach 1:
The air pump is positioned within the exhaust manifold structure, with the air pump inlet facing the exhaust manifold. This nesting arrangement allows the air pump to be integrated into the existing exhaust system space, eliminating the need for separate mounting space and reducing overall device complexity while maintaining exhaust gas purification functionality.
Solution Approach 2:
The exhaust manifold serves dual functions: it collects exhaust gases from cylinders and simultaneously houses the air pump inlet. This multi-functionality reduces the number of separate components needed, simplifying spatial arrangement while ensuring reliable exhaust gas purification through the catalytic converter.
2Object-affected harmful factors
If air pump inlet is positioned higher than engine inside cowling to prevent water mixing, then water intrusion is prevented, but device complexity and installation difficulty increase
Solution Approach 1:
The air pump inlet is positioned to face the exhaust manifold where exhaust gases naturally flow. By utilizing the existing exhaust gas flow path and pressure, the system prevents water intrusion without requiring complex elevated positioning or additional protective structures, simplifying installation while maintaining protection against water contamination.
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 enables effective compactification of the outboard motor by allowing for the efficient arrangement of secondary air supply components, preventing water interference, and enhancing exhaust gas purification without increasing the motor's size.
Implementation Method 1
a check valve configured to permit only a flow of the secondary air to the exhaust passage side
Implementation Method 2
an air pump configured to supply the secondary air to the exhaust passage is provided in order to supply oxygen necessary to oxidize and detoxify hydrocarbons and carbon monoxides contained in the exhaust gas
Implementation Method 3
The secondary air supply system has an intake silencer
Data Source
AI summary
In an exhaust passage, an exhaust manifold connected to exhaust ports of each cylinder of an engine body and formed to extend vertically is arranged in a side portion of a cylinder head. A secondary air supply system has an intake silencer, a check valve configured to permit only a flow to the exhaust passage side, a secondary air supply control valve configured to control a flow rate of the secondary air, and a secondary air supply passage configured to connect those components to each other and the exhaust passage. The secondary air supply system is arranged in a side portion of a cylinder block placed between a crankcase of the engine body and an assembly of the exhaust manifold and the cylinder head.